ARTICLE IN PRESS
DENTAL-2459; No. of Pages 8
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/dema
Retrospective evaluation of posterior direct composite restorations: 10-Year findings Edina Lempel a,∗ , Ákos Tóth b , Tamás Fábián a , Károly Krajczár a , József Szalma c a b c
Department of Restorative Dentistry and Periodontology, University of Pécs, Pécs, Hungary Faculty of Sciences, University of Pécs, Pécs, Hungary Department of Oral and Maxillofacial Surgery, University of Pécs, Pécs, Hungary
a r t i c l e
i n f o
a b s t r a c t
Article history:
Objectives. This 10-year retrospective study investigated the differences in the changes and
Received 2 February 2014
the longevity of Class II restorations using 4 similar microhybrid resin composites (Filtek
Received in revised form
Z250, Herculite XR, Gradia Direct Posterior, Renew).
16 April 2014
Methods. Data were collected from patient records. Those patients who received posterior
Accepted 3 November 2014
restoration between 2001 and 2003, and who still visited the clinical practice for regular
Available online xxx
check-up visits were selected. A total of 225 adult patients (86 males, 139 females) with 701 restorations were evaluated by 2 operators using the USPHS criteria. Data were analyzed
Keywords:
with Fisher’s Exact Test, Pearson’s Chi-Square Test and Kaplan–Meier analysis (p < 0.05).
Microhybrid resin composite
Results. A failure rate of 2.1% was detected. The reasons of failures included restoration
Class II restoration
fracture, secondary caries and endodontic treatment. Similar survival rates for Gradia Direct
USPHS evaluation
Posterior (91.25%) and Renew (92.19%) were observed; better performance was observed with
Longevity
the Filtek Z250 (99.1%) and Herculite XR (98.64%). There was a higher probability of failure in 3 surface (n = 10) than in 2 surface (n = 5) restorations (p < 0.001), and this rate was similar when molars (n = 8) and premolars (n = 7) were compared. The most frequent but clinically acceptable deficiency was the marginal discoloration. Significance. All four microhybrid resin composites showed acceptable clinical durability in Class II restorations during the 10-year follow-up period, with an overall survival rate of >97.8%. Higher rates of failures and deficiencies were observed with the Renew (fracture) and Gradia Direct Posterior (color match), respectively. © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
1.
Introduction
In recent years, resin composite (RC) has been considered a suitable, direct posterior filling material, and it has exhibited
acceptable survival rates in clinical studies [1–3]. Hybrid RCs can be considered the best materials for posterior restorations because these materials performed the most adequately in clinical studies [4]. The latest generation of microhybrid RCs contains 0.5–1.0-m filler particles of glass or zirconium and
∗ Corresponding author at: Department of Restorative Dentistry and Periodontology, University of Pécs, 5 Dischka Gy Street, Pécs H-7621, Hungary. Tel.: +36 72 535926; fax: +36 72 535905. E-mail address: [email protected] (E. Lempel).
http://dx.doi.org/10.1016/j.dental.2014.11.001 0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
2
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
smaller amounts of colloidal silica particles (40 nm in size), resulting in lower shrinkage and improved polish retention and better esthetics. Factors related to the material’s characteristics, to the patient, operator, to the tooth and cavity size have been reported in the literature as potentially relevant for restoration failures [1,2,5–7], although evidence of high failure rates in the short- to long-term are seldom found in clinical studies investigating hybrid RCs [8–11]. Meanwhile, considerable differences exist in the properties of the commercial RCs. These differences mainly include the filler loading level, particle material, morphology, size and matrix characteristics [12–14]. The elastic modulus, wear resistance, hardness and other properties of these different types of RCs have been shown to be fairly variable in in vitro studies, affecting the durability of specific RC materials [13,15,16]; however, large differences in clinical behavior have not yet been demonstrated [7,17]. There are many clinical trials which investigate the differences in the longevity of RC materials with different characteristics [8,11,18], however there are only a few studies which compare the long term durability of RCs from the same class, i.e. microhybrids [19]. The dentist’s choice from the wide range of RCs on the market depends on many factors. The indication area, handling, polishing ability and the price are only a few potential factors. The longevity of a RC is an important factor in material selection. To estimate how long the posterior RC restorations last, long-term studies are needed to identify the modes of failure and the possible reasons for these failures. The most commonly published evaluations are prospective studies, and according to their results, the routine application of RCs in the molar region is relevant [3,8,10,11,20,21]. Restoration longevity may be assessed by randomized controlled clinical trials, prospective and retrospective studies, cross-sectional analysis and cohort studies. Long term studies are a real challenge to perform, as study populations wear out and recall rates tend to drop to low levels. Retrospective longitudinal studies have shown to be able to result in observation times of more than 10 years [1,2,7,19,23]. However, some problems are known in relation with the retrospective design. It results in an obvious lack of standardization of indication and treatment protocols, although if conditions are well described and performed by one or just a few operator, the potential of the restorative material may be reflected [1,2,19]. According to short- and long-term prospective and retrospective studies, the most frequent defects and failures are fractures, secondary caries and marginal leakage formation [9,22,24–28]. The purpose of this retrospective study was to investigate the longevity of Class II posterior restorations, according to the USPHS criteria, in clinical practice using 4 microhybrid RCs with slightly different filler types and resin matrix characteristics. Further aims were to evaluate the most frequent defects and determine their correlation with the size and material of the restoration and to compare the frequency of the defects in the molar and the premolar regions. The null hypothesis stated that, when placed in Class II preparations in adults, the durability of the direct placement of RC restorations from
4 microhybrid RC materials in molars and premolars with different cavity types would not be significantly different after 10 years.
2.
Materials and methods
2.1.
Patients’ selection
For this retrospective study, 225 adult patients were selected according to pre-determined inclusion criteria from the registers of a Hungarian clinical practice (University of Pécs), from January 2001 to December 2003. The drop-out rate is presented in Fig. 1.The inclusion criteria were the following: good oral hygiene, absence of any pulpal and periodontal disease from the tooth to be restored, absence of known allergic symptoms for dental resins, being able to control the moisture during the restorative procedure. Furthermore, patients who were selected for the study had full dentition and normal occlusion, as verified by the clinical and radiographic records, and these patients had remained in continuous clinical followup for the last 9–11 years, including at least 1 annual recall without attending other dentists. Reasons for placement of RC were primary caries and the choice of using RC and not amalgam was requested by the patients because of esthetic or non-metallic reasons. Further requirements had to be fulfilled in order for the placement of RC: the oro-vestibular size of the cavity should not be bigger than the 1/3–2/3 of the oro-vestibular cusp-cusp distance; the margins are placed on enamel; there were no missing cusps. The restorations were placed using one of the 4 microhybrid RCs composed of slightly different material properties. Some important material data are shown in Table 1. The patients gave their written, informed consent prior to the start of the clinical evaluation, and 2 authors (EL and TF) carried out the clinical examinations. The study protocol was approved by the Regional Research Ethics Committee of University of Pécs (3410.1/2009). The patients had 701 Class II RC restorations in their permanent molars and premolars. The patient group consisted of 86 male and 139 female patients, with ages ranging from 21 to 55 years old. The type and number of restorations of the teeth included in the study are shown in Table 2.
Fig. 1 – Drop-out figure.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
ARTICLE IN PRESS
DENTAL-2459; No. of Pages 8
Renew
Kerr, Orange, CA, USA GC America, Inc., Alsip, IL, USA Bisco Inc., Schaumburg, IL, USA Herculite XR Gradia Direct Posterior
Abbreviations: Bis-GMA: bisphenol A diglycidil ether dimethacrylate; UDMA: urethane-dimethacrylate; Bis-EMA: ethoxylatedbisphenol-A dimethacrylate; TEGDMA: triethylene glycol dimethacrylate; BPDMA: bisphenol-A-dimethacrylate.
61 (8.8%) 57 0.7
296 (42.6%) 33 (4.7%) 59 65 0.6 0.85
Bariumglass, silica dioxide Fluoro-alumino-silicate glass, prepolymerized Silica dioxide Silica dioxide, aluminum oxide, barium oxide
305 (43.9%) 60 0.6 Zirconia-silica
Bis-GMA, UDMA, Bis-EMA, TEGDMA Bis-GMA, TEGDMA UDMA, dimethacrylate co-monomers Bis-GMA, TEGDMA, BPDMA 3M ESPE, St. Paul, MN, USA Filtek Z250
Resin matrix Manufacturer Name
Table 1 – Restorative composite materials used in this study.
Fillers
Average size (m)
Volume %
n (%)
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
2.2.
3
Restorative procedures
All restorations were placed by one operator (EL) between 2001 and 2003. Operative procedures were performed under local anesthesia if it was necessary. Caries were removed under constant water cooling. After color selection, the operative field was carefully isolated using cotton rolls and the suction device. For all cavities a thin metallic matrix (Hawe Neos, Bioggio, Switzerland) was used and careful wedging was performed with wooden wedges (Hawe Neos, Bioggio, Switzerland). Calcium-hydroxide (Dycal, DeTrey Dentsply, Konstanz, Germany) was used for the protection of the dentinpulp complex in deep cavities with close relation to the pulp. Calcium-hydroxide was covered with a thin layer of conventional glass-ionomer cement (Ketac-Fil, 3M ESPE, St. Paul, MN, USA). After setting of the base cement, all cavities were conditioned with a 37% phosphoric acid (3M ESPE, St. Paul, MN, USA) total etch technique. The acid gel was first applied on the enamel for 10 s, followed by 10 s on both dentin and enamel. After 20 s rinsing and careful drying of the cavity with air was performed (wet bonding technique), one step etch-and-rinse enamel-dentin adhesive system (Adper Single Bond, 3M ESPE, St. Paul, MN, USA) was applied with a minimal application time of 10 s and it was carefully dried to evaporate the solvent. The adhesive was cured with a quartz-tungsten-halogen curing unit (light intensity: 470 mW/cm2 ) (Cromalux 75, MegaPhysik, Berlin, Germany) for 20 s. The RCs were placed using a wedge-shaped oblique incremental technique [29]; each increment (max. 2 mm) was photo activated for 40 s. After checking the occlusion/articulation, the final polishing was performed with fine-grit diamonds (60 and 40 m grit) finishing burs to remove gross excess, followed by polishing with rubber points (Shofu brownie points, Shofu Co, Japan) and with aluminum oxide strips (Sof-Lex Finishing strips, 3M ESPE, St. Paul, MN, USA) for the interproximal surfaces until all restorations were considered clinically acceptable.
2.3.
Evaluation and statistical analysis
The history of the restorations was initially investigated from the dental records. If a restoration had failed, resulting in either replacement or repair, it was considered a failure, and both the data and the reason for failure were recorded. Replacements or repairs due to caries in a non-filled surface of a tooth with an acceptable RC were not considered reasons for failure. The restorations were then clinically evaluated by two examiners between October 2012 and December 2012 using an explorer and a dental mirror. The dentists were trained and calibrated before the start of the evaluation. When disagreements arose during the evaluations, a consensus was obtained among the examiners. The evaluation was performed according to the USPHS guidelines [30,31]. The following characteristics of the restorations were assessed: secondary caries, fracture, color match, marginal discoloration, anatomic form, marginal integrity and surface texture. The characteristics were assessed according to the following criteria:
Alpha (A) – restoration without changes or clinical remarks.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
4
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
Table 2 – Distribution of evaluated restorations according to material, tooth type and number of surfaces. Filtek Z250
Herculite XR
Gradia Direct
Renew
Total
Two surfaces Three surfaces
118 76
88 18
10 5
16 11
232 110
Premolars
Two surfaces Three surfaces
76 35
141 50
14 6
27 10
258 101
305
297
35
64
701
Total
Bravo (B) – restoration with changes that are clinically acceptable and without need for replacement. Charlie (C) – restoration with major changes that require the replacement of the restoration, which were clinically unacceptable.
The surfaces were dried with an air stream before evaluation, except for color scoring. Approximal surface control was performed with the help of dental flosses and with a Gottlieb probe. Radiographs were only made in those cases when the clinical examination indicated (by the patient’s complaints, marginal gap formation especially gingivally, shadow under the sound enamel near the restoration, food retention interproximally, high level of plaque accumulation especially interproximally) that it was necessary for the completion of the examination, in order to avoid unnecessary radiation exposure [32]. The data collection and the statistical analysis were performed using SPSS for Windows 17.0 (SPSS, Chicago, IL, USA). Descriptive statistics were used to describe the frequency distributions of the evaluated criteria and the reasons for failure. Qualitative analysis based on the USPHS criteria was analyzed independently for each of the 7 evaluated clinical characteristics. Differences in the qualitative criteria between the 4 materials were analyzed using Fisher’s Exact Test. Furthermore, Pearson’s Chi-Square Test was applied to evaluate the influence of the material, tooth type and cavity size on the results. The hypothesis was rejected at the 5% level. The analysis of the survival of the restorations was performed with the Kaplan–Meier method.
3.
Results
In the present study, a total of 701 posterior RC restorations were evaluated (Fig. 1). The date of the placement and the date of the failure were obtained from the dental records. Of the 701 restorations, 15 (2.1%) were determined to be unacceptable. The reasons for the failure included secondary caries, fracture of the restoration and endodontic treatment. In Table 3 failures for each of the 4 evaluated RCs after 10 years of clinical service are shown. All restorations given a “Charlie” rating were regarded as failed. Endodontic treatment was recorded as a reason for the failure of the restoration, and then the restoration was excluded from the following evaluation, because the USPHS criteria does not contain this clinical characteristic. Pulp protection was performed in 29 cases (n = 12 for Filtek Z250, n = 10 for Herculite XR, n = 2 for Gradia Direct Posterior and n = 5 for Renew) from which in 3 cases endodontic
Cumulave survival (%)
Molars
100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85
Filtek Z250 Herculite XR Gradia Direct Renew
0
5
6
7
8
9
10
11
12
Follow up me (years)
Fig. 2 – Cumulative survival rate of the four microhybrid composite resins.
treatment was necessary (n = 1 for Herculite XR, n = 1 for Gradia Direct Posterior and n = 1 for Renew). Fig. 2 shows the Kaplan–Meier survival curve for the 4 materials over 11 years of service. The overall success during the registration period was 97.86%. The failure rates for Filtek Z250 and Herculite XR were constant, 0.9% and 1.36%, respectively, after 11 years; however, an increasing failure rate was observed for Renew (7.81%) and Gradia Direct Posterior (8.57%), and these increased failure rates were significantly higher (p < 0.05) than the rates for Filtek Z250 and Herculite XR. A comparison between the RCs according to the USPHS criteria is presented in Table 4. A total of 349 (50.2%) restorations were accepted without changes and clinical remarks (A score), and in 346 (49.8%) cases, at least 1 deficiency was found (B or C score). The incidence of deficiencies (B and C codes) was 60% when the restorations were made with Filtek Z250, 72% with Renew, 81% with Herculite XR and 82% with Gradia Direct Posterior. The differences in the numbers of B and C codes between Filtek Z250 and Herculite XR (p = 0.015) or Filtek Z250 and Gradia Direct Posterior (p = 0.013) were statistically significant over the total observation period. Pearson’s Chi-Square test revealed a significantly higher rate of B and C scores in the color matching of Gradia Direct Posterior (p = 0.02) and in the fracture of Renew (p = 0.005); however, it should be mentioned that fractures were found in only 2 cases of the 61 Renew fillings. Considering the number of surfaces, in Filtek Z250, significantly more B and C scores were found in cases of 3 surface (MOD) restorations than in 2 surface (MO, OD) fillings (p < 0.001). Similar tendencies were observed in the other materials; however, these differences were not significant. Additionally, significantly greater marginal discolorations (p = 0.001) and anatomic form deficiencies (p = 0.02) were found in 3 surface RC fillings, independent of the type of material. The most frequent deficiency was the marginal discoloration (p = 0.027) among the
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
ARTICLE IN PRESS
DENTAL-2459; No. of Pages 8
5
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
Table 3 – Failed restorations by material during the 12-year monitoring period. Cause of failure
Materials FiltekZ250
Restoration fracture Secondary caries Endodontic treatment Total
1 2 0 3
HerculiteXR 0 3 1 4
Time of failure (years) Gradia 0 1 2 3
evaluated variables. Considering the type of tooth, restorations in premolars had similar survival rates as restorations in molars, although towards molars a growing trend could be observed.
4.
Discussion
In this retrospective clinical study, the long-term clinical performance of 4 microhybrid RC restoratives applied in Class II cavities was analyzed over an extended period of time. The main objective of the study was to observe whether microhybrid RCs with slightly different compositions of the resin matrix and different types, but similar sizes and volume fractions of filler particles showed distinct clinical performances. The number of long-term studies is low because they are time consuming and factors such as patient compliance, recall failure make these studies complicated. High drop-out rates and/or low number of participants have been a further weakness [4,33]. In the present study the recall rate was 83% after 10 years (9–11.5 years). It may be explained by the fact that these patients are mostly employees of the university. The main reason of drop-out was mostly the migration of involved students after their graduation. In contrast with a prospective, randomized clinical trial – for longevity analysis of different materials – a retrospective designed study may result in some deficiencies, such as the incomplete standardization of indications, treatment protocols or the missing baseline scoring. However, in the present study the involved practitioner was a university instructor, working according to high standards and mainly performing RC restorations for demonstrations for undergraduate and graduate education. Moreover, the selected patient group for this study acted as presentational cases (mostly dentists, general medicine colleagues, dental stuff, dental and general medicine students), therefore requiring an excellent implementation. In addition, this is a well-motivated patient group with high socioeconomic level, subjected to periodical examinations, oral hygiene and to instructions regarding dietary habits. The above mentioned facts may minimize the non material originating factors which influence the longevity of RC restorations, thus the study may have the possibility to focus on the failures raising from the differences of the 4 microhybrid RC materials. Considering the overall service time, this study reported a 97.86% survival rate of posterior Class II RC restorations. The average annual failure rate for the 4 RC materials was 0.52%, and it varied between 0.08 and 0.71%. Opdam et al. concluded
Renew 2 0 3 5
0-5
6
7
8
9
10
11
12
Total
1 0 3 4
1 1 0 2
1 2 1 4
0 1 0 1
0 0 0 0
0 1 1 2
0 1 0 1
0 0 1 1
3 6 6 15
that a randomized clinical trial has the advantage to standardize methods and calibrate the operators. Among others this can explain why the results of randomized clinical studies are often better than those of retrospective studies [27]. In our retrospective study one operator performed all the evaluated RC restorations with the maximal adherence to the indications and steps of the adhesive technique. It may explain the good results which are comparable with long-term controlled prospective studies. According to Frankenberg et al. [8] the overall success rate of RC restorations after 8 years is 98.5%, and 2.4% cumulative failure rate was reported by van Dijken et al. after 12 years [10]. However, our results show better survival rate than other retrospective studies (i.e. according to Opdam et al. the overall success rate is 82.2% after 10 years) [27] where difficulties arise in the standardization of the procedure and the calibration of the operators. Although, Baldissera et al. [19] reported 95% survival rate of 3 microhybrid RC restorations after 10 years in a retrospective study. They concluded, that good results may be explained by the single and skilled operator – thus the influence of the operator in the results is limited – and by the high socioeconomic status and good oral hygiene of patients, similarly as in our investigation. It is more likely that patient and operator factors, both favorable in this study, are the main factors influencing restoration longevity, while material properties may have a secondary role [25]. In a recent study, van de Sande et al. reported that the failure of restorations is significantly higher in patients at high caries risk [34]. In a 6-year prospective randomized study, van Dijken et al. showed that 63% of the recurrent caries lesions were found in high caries risk participants and the overall success rate was 88.1% [11]. Similar to the findings of other investigations, the main reasons for the failures in this study were secondary caries, fracture and endodontic treatment [1,2,5,9,26,27]; however, the occurrence of failures was low in the present study which may be explained by the above mentioned facts. Overall, the results showed that it is possible to place posterior RC restorations with considerable success and low failure rates, although a slightly increasing failure rate over the course of time was observed for 2 materials (8.37% for Gradia Direct Posterior and 7.81% for Renew). For example, when looking at the time interval, it was observed that Filtek Z250 (AFR 0.08%) and Herculite XR (AFR 0.1%) had a significantly better long-term survival. Baldissera et al. found similar good results with Herculite XR, presenting 0.3% AFR in their long-term retrospective study [19]. In contrast, Da Rosa Rodolpho et al. reported 1.5% AFR for Herculite XR after 10 years and a further increase (2.2%) was observed when the observation time was extended [1]. Unfortunately, there is a lack of long-term clinical studies with Renew or Filtek Z250, however our previous 5-year
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
6
ARTICLE IN PRESS
0.462 0.005 0.020 0.269 0.469 0.116 0.094 100/0 97.0/3.0# 80.3/19.7 77.0/33.0 90.2/9.8 85.2/14.8 100/0 0 2 0 0 0 0 0 0 12 14 6 9 0 61 59 49 47 55 52 61 “A” – Restorations with Alpha score – restoration without changes or clinical remarks. “B” – Restorations with Bravo score – restoration with changes that are clinically acceptable and without need for replacement. “C” – Restorations with Charlie score – restoration with major changes which require replacement of the restoration. ∗ Pearson’s Chi-Square and Fisher’s Exact test (p < 0.05). # Significantly differing variables.
97.0/3.0 100/0 79.0/21.0# 73.0/27.0 85.0/15.0 91.0/9.0 94.0/6.0 1 0 0 0 0 0 0 0 7 9 5 3 2 32 33 26 24 28 30 31 99.0/1.0 100/0 85.1/14.9 73.0/27.0 82.0/18.0 85.1/14.9 94.9/5.1 3 0 0 0 0 0 0 0 44 80 53 44 15 293 296 252 216 243 252 281 99.4/0.6 99.7/0.3 89.2/10.8 79.0/21.0 84.3/15.7 91.5/8.5 97.4/2.6 2 1 0 0 0 0 0 0 33 64 48 26 8 303 304 272 241 257 279 297 Secondary caries Fracture Color match Marginal discoloration Anatomic form Marginal integrity Surface roughness
A/(B + C) (%) A/(B + C) (%) C B A/(B + C) (%) C B A
B
C
A/(B + C) (%)
A
Herculite XR (n = 296) Filtek Z250 (n = 305)
Table 4 – Comparison between the composites according to the USPHS criteria.
A
Gradia Direct (n = 33)
A
B
C
Renew (n = 61)
p-value*
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
retrospective evaluation of Class II restorations reported 98.8% success rate with Filtek Z250 [35]. Additionally, Filtek Z250 was commonly used to compare different properties of new materials in in vitro studies [36–38]. Increase in the annual failure rates of Gradia Direct Posterior and Renew were observed during the first five years of the observation period. In a 6-year prospective study van Dijken et al. reported 8.5% failure rate for Gradia Direct Posterior which is similar to our findings (8.37%), however the observation time is longer in the present study [39]. While the annual failure rate of Renew remained constant, the failure rate of Gradia Direct Posterior further increased after 11 years. Despite the fact that significant differences were found in the failure rates after 10 years, these materials had a long service time with clinically acceptable changes. Our results suggest that the follow-up time should be extended, as differences in the materials mostly emerge after more than 10 years. As one of the main reasons for restoration failure, fractures may indicate that Renew has lower long-term fracture resistance, most likely due to its lower E-modulus, which, in turn, is related to the slightly lower filler volume, which therefore increases the clinical effects of fatigue, compared to the other investigated materials. In vitro studies have shown that higher filler volumes increase the fracture toughness of restoratives, even after simulated occlusal loading [40,41]. On the other hand, lower filler volume implies higher monomer content. Because monomers are responsible for polymerization shrinkage, contraction stress may result in the fracture of the tooth or restoration [42]. The clinical data also indicated that other minor differences in material composition and properties may affect the clinical behavior of RC restorations. Gradia Direct Posterior showed a significantly greater change in color match; this could be explained by its larger average particle size, which may lead to an increased rate of extrinsic discoloration [43,44]. Furthermore, the amount of unreacted matrix monomers, photo-initiators and co-initiators has a considerable influence on the discoloration of the RC [45]. One of the limitations of our study is the relative low case number from Renew and Gradia Direct Posterior compared to the other materials. Increasing these case numbers may result in more reliable data. In accordance with other studies [3,7,19,27,46], our results showed that the amount of restored surfaces has a considerable effect on the quality of the restoration. Significantly more B codes were found in the MOD restoration cases made using Filtek Z250 than in the 2 surface restoration cases or in cases using the other materials. Independent of the materials, the anatomic form deficiencies in the cases of 3 surface restorations were higher levels than in 2 surface restorations. This could be explained by the larger RC surface, which wears under abrasive attacks, leading to a loss of material. Similarly to Gordan et al., marginal discoloration was the most frequent defect observed in the restorations, independent of the RC used [47]. In general, marginal quality decreases over time due to physiological and chemical interactions with the oral environment, and the onset of degradation could imply problems associated with the adhesive or the RC. Concerning the use of the adhesive system there are controversies in the literature. Some authors combine the RC material with the adhesive of the respective manufacturer
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
[8,11,39], however, others use only one type of adhesive for different RCs [19,27]. Demarco et al. and Lynch et al. in their review articles focused on the type of adhesives they preferred to use, instead of focusing on the relevance of the combination of RC material with the adhesive of the respective manufacturer [25,48]. In the present study one universal total-etch adhesive system was used for all of the 4 materials. This may standardize the adhesive procedure and exclude the changes which may be originated from the different adhesive systems, therefore, a direct comparison between the differences of the microhybrid RCs may be made. There are inconsistent findings concerning the effect of tooth type. Some articles have reported that restorations placed in premolars exhibited significantly better survival rates than those placed in molars [1,3,7,8,46,28]. This is suspected to be due to the greater occlusal forces on molar restorations compared with those in premolars. Another possible explanation is the decreased access to the operating field when restoring molars. However, our results cannot confirm these findings. Similar to the findings of Aoyama et al. [24], our results showed no significant effect of tooth type on the longevity or quality of posterior RC restorations.
5.
Conclusions
Within the limitations of this retrospective study, the following conclusions can be drawn: • All 4 microhybrid resin composites showed acceptable clinical durability in Class II restorations during the 10-year follow-up period, with an overall survival rate of 97.9%. • When considering the differences according to the USPHS criteria, higher rates of B and C codes were observed in the Renew (fracture) and Gradia Direct Posterior (color match) (p < 0.05) restorations; therefore, the null hypothesis was rejected.
Acknowledgements We would like to thank Professor Dr Ralf Schulze (Johannes Gutenberg-University of Mainz, Germany) for his valuable advices in this research work. This work was supported by PTE ÁOK-KA-2013/5 and a 2013/26 Research Grant.
references
[1] Da Rosa Rodolpho PA, Donassollo TA, Cenci MS, Loguércio AD, Moraes RR, Bronkhorst EM, et al. 22-year clinical evaluation of the performance of two posterior composites with different filler characteristics. Dent Mater 2011;27:955–63. [2] Opdam NJM, Bronkhorst EM, Loomans BA, Hujsmans MC. 12-year survival of composite vs. amalgam restorations. J Dent Res 2010;89:1063–7. [3] Pallesen U, van Dijken JWV, Halken J, Hallosten AL, Höigaard R. Longevity of posterior resin composite restorations in permanent teeth in Public Dental Health Service: a prospective 8 years follow up. J Dent 2013;41:297– 306.
7
[4] Manhart J, Chen H, Hamm G, Hickel R. Buonocore memorial lecture. Review of the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition. Oper Dent 2004;29:481–508. [5] Bernardo M, Luis H, Martin MD, Leroux BG, Rue T, Leitao J, et al. Survival and reason for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial. J Am Dent Assoc 2007;138: 775–83. [6] Burke FJ, Lucarotti PS. How long do direct restorations placed within the general dental services in England and Wales survive? Br Dent J 2009;206:E2. [7] Da Rosa Rodolpho PA, Cenci MS, Donassollo TA, Loguercio AD, Demarco FF. A clinical evaluation of posterior composite restorations: 17-year findings. J Dent 2006;34: 427–35. [8] Frankenberger R, Reinelt C, Krämer N. Nanohybrid vs. fine hybrid composite in extended class II cavities: 8-year results. Clin Oral Investig 2014;18:125–37. [9] Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior dental restorations and reasons for failure. Eur J Oral Sci 2012;120:539–48. [10] van Dijken JWV. Durability of resin composite restorations in high C-factor cavities: A 12-year follow-up. J Dent 2010;38:469–74. [11] van Dijken JWV, Pallesen U. A six-year prospective randomized study of a nano-hybrid and a conventional hybrid resin composite in Class II restorations. Dent Mater 2013;29:191–8. [12] Beun S, Glorieux T, Devaux J, Vreven J, Leloup G. Characterization of nanofilled compared to universal and microfilled composites. Dent Mater 2007;23:51–9. [13] Blackham JT, Vandewalle KS, Lien W. Properties of hybrid resin composite systems containing prepolymerized filler particles. Oper Dent 2009;34(6):697–702. [14] de Moraes RR, Goncalves LS, Lancellotti AC, Consani S, Correr-Sobrinho L, Sinhoreti MA. Nanohybrid resin composites: nanofiller loaded materials or traditional microhybrid resins? Oper Dent 2009;34:551–7. [15] Lohbauer U, Frankenberger R, Kramer N, Petschelt A. Strength and fatigue performance versus filler fraction of different types of direct dental restoratives. J Biomed Mater Res B Appl Biomater 2006;76:114–20. [16] Venturini D, Cenci MS, Demarco FF, Camacho GB, Powers JM. Effect of polishing techniques and time on surface roughness, hardness and microleakage of resin composite restorations. Oper Dent 2006;31:11–7. [17] Cenci MS, Lund RG, Pereira CL, de Carvalho RM, Demarco FF. In vivo and in vitro evaluation of Class II composite resin restorations with different matrix systems. J Adhes Dent 2006;8:127–32. [18] Palaniappan S, Bharadwaj D, Mattar DL, Peumans M, Van Meerbeek B, Lambrechts P. Nanofilled and microhybrid composite restorations: five-year clinical wear performances. Dent Mater 2011;27:692–700. [19] Baldissera RA, Corrêa MB, Schuch HS, Collares K, Nascimento GG, Jardim PS, et al. Are there universal restorative composites for anterior and posterior teeth? J Dent 2013;41:1027–35. [20] Kiremitci A, Alpaslan T, Gurgan S. Six-year clinical evaluation of packable composite restorations. Oper Dent 2009;34:11–7. [21] Kuper NK, Opdam NJM, Bronkhorst EM, Hujsmans MCDNJM. The influence of approximal restoration extension on the development of secondary caries. J Dent 2012;40: 241–7. [22] Padr R, Cenci MS, Donassollo TA, Loguercio AD, Demarco FF. A clinical evaluation of posterior composite restorations: 17-year findings. J Dent 2006;134:427–35.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
8
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
[23] van Nieuwenhuysen JP, D’Hoore W, Carvalho J, Qvist V. Long-term evaluation of extensive restorations in permanent teeth. J Dent 2003;31:395–405. [24] Aoyama T, Aida J, Takehara J, Morita M. Factors associated with the longevity of restorations in posterior teeth. J Dent Health 2008;58:16–24. [25] Demarco FF, Correa MB, Cenci MS, Moraes RR, Opdam NJM. Longevity of posterior composite restorations: not only a matter of materials. Dent Mater 2012;28:87–101. [26] Lindberg A, van Dijken JW, Lindberg M. Nine-year evaluation of a polyacid-modified resin composite/resin composite open sandwich technique in Class II cavities. J Dent 2007;35:124–9. [27] Opdam NJM, Bronkhorst EM, Rooters JM, Loomans BAC. A retrospective clinical study on longevity of posterior composite and amalgam restorations. Dent Mater, 2007;23:2–8. [28] Pallesen U, Qvist V. Composite resin fillings and inlays. An 11-year evaluation. Clin Oral Investig 2003;7:71–9. [29] Weaver WS, Blank LW, Pelleu Jr GB. A visible light activated resin cured through tooth structure. Gen Dent 1988;36:236–7. [30] Ryge G, Snyder M. Evaluating the clinical quality of restorations. J Am Dent Assoc 1973;87:369–77. [31] Ryge G. Clinical criteria. Int Dent J 1980;30:347–58. [32] European Commission. European guidelines on radiation protection in dental radiology. The safe use of radiographs in dental practice. Radiat Prot 2004;136. [33] Brunthaler A, Konig F, Lucas T, Sperr W, Schedle A. Longevity of direct resin composite restorations in posterior teeth. Clin Oral Investig 2003;7:63–70. [34] van de Sande FH, Opdam NJ, Rodolpho PA, Corrêa MB, Demarco FF, Cenci MS. Patient risk factors’ influence on survival of posterior composites. J Dent Res 2013;92:785–838. [35] Lempel E, Szalma J, Jeges S, Kende D, Krajczár K, Nagy ÁK, et al. Retrospective study of direct composite restorations according to the USPHS criteria. Fogorvosi Szle 2012;105:47–52. [36] Lempel E, Czibulya Zs, Kunsági-Máté S, Szalma J, Sümegi B, Böddi K. Quantification of conversion degree and monomer elution from dental composite using HPLC and micro-Raman Spectroscopy. Chromatographia 2014;77:1137–44.
[37] Garoushi S, Säilynoja E, Vallittu PK, Lassila L. Physical properties and depth of cure of a new short fiber reinforced composite. Dent Mater 2013;29:835–41. [38] Watanabe H, Khera SC, Vargas MA, Qian F. Fracture toughness comparison of six resin composites. Dent Mater 2008;24:418–25. [39] van Dijken JWV. A 6-year prospective evaluation of a one-step HEMA-free self etching adhesive in Class II restorations. Dent Mater 2013;29:1116–22. [40] Ferracane JL, Condon JR. In vitro evaluation of the marginal degradation of dental composites under simulated occlusal loading. Dent Mater 1999;15:262–7. [41] Ilie N, Hickel R. Investigations on mechanical behavior of dental composites. Clin Oral Investig 2009;13:427–38. [42] Meredith N, Setchell DJ. In vitro measurement of cuspal strain and displacement in composite restored teeth. J Dent 1997;25:331–7. [43] Nasim I, Neelakantan P, Sujeer R, Subbarao CV. Color stability of microfilled, microhybrid and nanocomposite resins—an in vitro study. J Dent 2010;38:137–42. [44] Yu B, Lim HN, Lee YK. Influence of nano- and micro-filler proportions on the optical property stability of experimental dental resin composites. Mater Des 2010;31: 4719–24. [45] Schneider LFJ, Pfeifer CSC, Consani S, Prahl SA, Ferracane JL. Influence of photoinitiator type on the rate of polymerization, degree of conversion, hardness and yellowing of dental resin composites. Dent Mater 2008;24:1169–77. [46] Opdam NJM, Bronkhorst EM, Roeters JM, Loomans BA. Longevity and reasons for failure of sandwich and total-etch posterior composite resin restorations. J Adhes Dent 2007;9:469–75. [47] Gordan VV, Garvan CW, Blaser PK, Mondragon E, Mjör IA. A long-term evaluation of alternative treatments to replacement of resin-based composite restorations: results of a seven-year study. J Am Dent Assoc 2009;140: 1476–84. [48] Lynch CD, Opdam NJ, Hickel R, Brunton PA, Gurgan S, Kakaboura A, et al. Guidance on posterior resin composites: Academy of Operative Dentistry – European Section. J Dent 2014;42:377–83.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
Available online at www.sciencedirect.com
ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/dema
Retrospective evaluation of posterior direct composite restorations: 10-Year findings Edina Lempel a,∗ , Ákos Tóth b , Tamás Fábián a , Károly Krajczár a , József Szalma c a b c
Department of Restorative Dentistry and Periodontology, University of Pécs, Pécs, Hungary Faculty of Sciences, University of Pécs, Pécs, Hungary Department of Oral and Maxillofacial Surgery, University of Pécs, Pécs, Hungary
a r t i c l e
i n f o
a b s t r a c t
Article history:
Objectives. This 10-year retrospective study investigated the differences in the changes and
Received 2 February 2014
the longevity of Class II restorations using 4 similar microhybrid resin composites (Filtek
Received in revised form
Z250, Herculite XR, Gradia Direct Posterior, Renew).
16 April 2014
Methods. Data were collected from patient records. Those patients who received posterior
Accepted 3 November 2014
restoration between 2001 and 2003, and who still visited the clinical practice for regular
Available online xxx
check-up visits were selected. A total of 225 adult patients (86 males, 139 females) with 701 restorations were evaluated by 2 operators using the USPHS criteria. Data were analyzed
Keywords:
with Fisher’s Exact Test, Pearson’s Chi-Square Test and Kaplan–Meier analysis (p < 0.05).
Microhybrid resin composite
Results. A failure rate of 2.1% was detected. The reasons of failures included restoration
Class II restoration
fracture, secondary caries and endodontic treatment. Similar survival rates for Gradia Direct
USPHS evaluation
Posterior (91.25%) and Renew (92.19%) were observed; better performance was observed with
Longevity
the Filtek Z250 (99.1%) and Herculite XR (98.64%). There was a higher probability of failure in 3 surface (n = 10) than in 2 surface (n = 5) restorations (p < 0.001), and this rate was similar when molars (n = 8) and premolars (n = 7) were compared. The most frequent but clinically acceptable deficiency was the marginal discoloration. Significance. All four microhybrid resin composites showed acceptable clinical durability in Class II restorations during the 10-year follow-up period, with an overall survival rate of >97.8%. Higher rates of failures and deficiencies were observed with the Renew (fracture) and Gradia Direct Posterior (color match), respectively. © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
1.
Introduction
In recent years, resin composite (RC) has been considered a suitable, direct posterior filling material, and it has exhibited
acceptable survival rates in clinical studies [1–3]. Hybrid RCs can be considered the best materials for posterior restorations because these materials performed the most adequately in clinical studies [4]. The latest generation of microhybrid RCs contains 0.5–1.0-m filler particles of glass or zirconium and
∗ Corresponding author at: Department of Restorative Dentistry and Periodontology, University of Pécs, 5 Dischka Gy Street, Pécs H-7621, Hungary. Tel.: +36 72 535926; fax: +36 72 535905. E-mail address: [email protected] (E. Lempel).
http://dx.doi.org/10.1016/j.dental.2014.11.001 0109-5641/© 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
2
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
smaller amounts of colloidal silica particles (40 nm in size), resulting in lower shrinkage and improved polish retention and better esthetics. Factors related to the material’s characteristics, to the patient, operator, to the tooth and cavity size have been reported in the literature as potentially relevant for restoration failures [1,2,5–7], although evidence of high failure rates in the short- to long-term are seldom found in clinical studies investigating hybrid RCs [8–11]. Meanwhile, considerable differences exist in the properties of the commercial RCs. These differences mainly include the filler loading level, particle material, morphology, size and matrix characteristics [12–14]. The elastic modulus, wear resistance, hardness and other properties of these different types of RCs have been shown to be fairly variable in in vitro studies, affecting the durability of specific RC materials [13,15,16]; however, large differences in clinical behavior have not yet been demonstrated [7,17]. There are many clinical trials which investigate the differences in the longevity of RC materials with different characteristics [8,11,18], however there are only a few studies which compare the long term durability of RCs from the same class, i.e. microhybrids [19]. The dentist’s choice from the wide range of RCs on the market depends on many factors. The indication area, handling, polishing ability and the price are only a few potential factors. The longevity of a RC is an important factor in material selection. To estimate how long the posterior RC restorations last, long-term studies are needed to identify the modes of failure and the possible reasons for these failures. The most commonly published evaluations are prospective studies, and according to their results, the routine application of RCs in the molar region is relevant [3,8,10,11,20,21]. Restoration longevity may be assessed by randomized controlled clinical trials, prospective and retrospective studies, cross-sectional analysis and cohort studies. Long term studies are a real challenge to perform, as study populations wear out and recall rates tend to drop to low levels. Retrospective longitudinal studies have shown to be able to result in observation times of more than 10 years [1,2,7,19,23]. However, some problems are known in relation with the retrospective design. It results in an obvious lack of standardization of indication and treatment protocols, although if conditions are well described and performed by one or just a few operator, the potential of the restorative material may be reflected [1,2,19]. According to short- and long-term prospective and retrospective studies, the most frequent defects and failures are fractures, secondary caries and marginal leakage formation [9,22,24–28]. The purpose of this retrospective study was to investigate the longevity of Class II posterior restorations, according to the USPHS criteria, in clinical practice using 4 microhybrid RCs with slightly different filler types and resin matrix characteristics. Further aims were to evaluate the most frequent defects and determine their correlation with the size and material of the restoration and to compare the frequency of the defects in the molar and the premolar regions. The null hypothesis stated that, when placed in Class II preparations in adults, the durability of the direct placement of RC restorations from
4 microhybrid RC materials in molars and premolars with different cavity types would not be significantly different after 10 years.
2.
Materials and methods
2.1.
Patients’ selection
For this retrospective study, 225 adult patients were selected according to pre-determined inclusion criteria from the registers of a Hungarian clinical practice (University of Pécs), from January 2001 to December 2003. The drop-out rate is presented in Fig. 1.The inclusion criteria were the following: good oral hygiene, absence of any pulpal and periodontal disease from the tooth to be restored, absence of known allergic symptoms for dental resins, being able to control the moisture during the restorative procedure. Furthermore, patients who were selected for the study had full dentition and normal occlusion, as verified by the clinical and radiographic records, and these patients had remained in continuous clinical followup for the last 9–11 years, including at least 1 annual recall without attending other dentists. Reasons for placement of RC were primary caries and the choice of using RC and not amalgam was requested by the patients because of esthetic or non-metallic reasons. Further requirements had to be fulfilled in order for the placement of RC: the oro-vestibular size of the cavity should not be bigger than the 1/3–2/3 of the oro-vestibular cusp-cusp distance; the margins are placed on enamel; there were no missing cusps. The restorations were placed using one of the 4 microhybrid RCs composed of slightly different material properties. Some important material data are shown in Table 1. The patients gave their written, informed consent prior to the start of the clinical evaluation, and 2 authors (EL and TF) carried out the clinical examinations. The study protocol was approved by the Regional Research Ethics Committee of University of Pécs (3410.1/2009). The patients had 701 Class II RC restorations in their permanent molars and premolars. The patient group consisted of 86 male and 139 female patients, with ages ranging from 21 to 55 years old. The type and number of restorations of the teeth included in the study are shown in Table 2.
Fig. 1 – Drop-out figure.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
ARTICLE IN PRESS
DENTAL-2459; No. of Pages 8
Renew
Kerr, Orange, CA, USA GC America, Inc., Alsip, IL, USA Bisco Inc., Schaumburg, IL, USA Herculite XR Gradia Direct Posterior
Abbreviations: Bis-GMA: bisphenol A diglycidil ether dimethacrylate; UDMA: urethane-dimethacrylate; Bis-EMA: ethoxylatedbisphenol-A dimethacrylate; TEGDMA: triethylene glycol dimethacrylate; BPDMA: bisphenol-A-dimethacrylate.
61 (8.8%) 57 0.7
296 (42.6%) 33 (4.7%) 59 65 0.6 0.85
Bariumglass, silica dioxide Fluoro-alumino-silicate glass, prepolymerized Silica dioxide Silica dioxide, aluminum oxide, barium oxide
305 (43.9%) 60 0.6 Zirconia-silica
Bis-GMA, UDMA, Bis-EMA, TEGDMA Bis-GMA, TEGDMA UDMA, dimethacrylate co-monomers Bis-GMA, TEGDMA, BPDMA 3M ESPE, St. Paul, MN, USA Filtek Z250
Resin matrix Manufacturer Name
Table 1 – Restorative composite materials used in this study.
Fillers
Average size (m)
Volume %
n (%)
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
2.2.
3
Restorative procedures
All restorations were placed by one operator (EL) between 2001 and 2003. Operative procedures were performed under local anesthesia if it was necessary. Caries were removed under constant water cooling. After color selection, the operative field was carefully isolated using cotton rolls and the suction device. For all cavities a thin metallic matrix (Hawe Neos, Bioggio, Switzerland) was used and careful wedging was performed with wooden wedges (Hawe Neos, Bioggio, Switzerland). Calcium-hydroxide (Dycal, DeTrey Dentsply, Konstanz, Germany) was used for the protection of the dentinpulp complex in deep cavities with close relation to the pulp. Calcium-hydroxide was covered with a thin layer of conventional glass-ionomer cement (Ketac-Fil, 3M ESPE, St. Paul, MN, USA). After setting of the base cement, all cavities were conditioned with a 37% phosphoric acid (3M ESPE, St. Paul, MN, USA) total etch technique. The acid gel was first applied on the enamel for 10 s, followed by 10 s on both dentin and enamel. After 20 s rinsing and careful drying of the cavity with air was performed (wet bonding technique), one step etch-and-rinse enamel-dentin adhesive system (Adper Single Bond, 3M ESPE, St. Paul, MN, USA) was applied with a minimal application time of 10 s and it was carefully dried to evaporate the solvent. The adhesive was cured with a quartz-tungsten-halogen curing unit (light intensity: 470 mW/cm2 ) (Cromalux 75, MegaPhysik, Berlin, Germany) for 20 s. The RCs were placed using a wedge-shaped oblique incremental technique [29]; each increment (max. 2 mm) was photo activated for 40 s. After checking the occlusion/articulation, the final polishing was performed with fine-grit diamonds (60 and 40 m grit) finishing burs to remove gross excess, followed by polishing with rubber points (Shofu brownie points, Shofu Co, Japan) and with aluminum oxide strips (Sof-Lex Finishing strips, 3M ESPE, St. Paul, MN, USA) for the interproximal surfaces until all restorations were considered clinically acceptable.
2.3.
Evaluation and statistical analysis
The history of the restorations was initially investigated from the dental records. If a restoration had failed, resulting in either replacement or repair, it was considered a failure, and both the data and the reason for failure were recorded. Replacements or repairs due to caries in a non-filled surface of a tooth with an acceptable RC were not considered reasons for failure. The restorations were then clinically evaluated by two examiners between October 2012 and December 2012 using an explorer and a dental mirror. The dentists were trained and calibrated before the start of the evaluation. When disagreements arose during the evaluations, a consensus was obtained among the examiners. The evaluation was performed according to the USPHS guidelines [30,31]. The following characteristics of the restorations were assessed: secondary caries, fracture, color match, marginal discoloration, anatomic form, marginal integrity and surface texture. The characteristics were assessed according to the following criteria:
Alpha (A) – restoration without changes or clinical remarks.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
4
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
Table 2 – Distribution of evaluated restorations according to material, tooth type and number of surfaces. Filtek Z250
Herculite XR
Gradia Direct
Renew
Total
Two surfaces Three surfaces
118 76
88 18
10 5
16 11
232 110
Premolars
Two surfaces Three surfaces
76 35
141 50
14 6
27 10
258 101
305
297
35
64
701
Total
Bravo (B) – restoration with changes that are clinically acceptable and without need for replacement. Charlie (C) – restoration with major changes that require the replacement of the restoration, which were clinically unacceptable.
The surfaces were dried with an air stream before evaluation, except for color scoring. Approximal surface control was performed with the help of dental flosses and with a Gottlieb probe. Radiographs were only made in those cases when the clinical examination indicated (by the patient’s complaints, marginal gap formation especially gingivally, shadow under the sound enamel near the restoration, food retention interproximally, high level of plaque accumulation especially interproximally) that it was necessary for the completion of the examination, in order to avoid unnecessary radiation exposure [32]. The data collection and the statistical analysis were performed using SPSS for Windows 17.0 (SPSS, Chicago, IL, USA). Descriptive statistics were used to describe the frequency distributions of the evaluated criteria and the reasons for failure. Qualitative analysis based on the USPHS criteria was analyzed independently for each of the 7 evaluated clinical characteristics. Differences in the qualitative criteria between the 4 materials were analyzed using Fisher’s Exact Test. Furthermore, Pearson’s Chi-Square Test was applied to evaluate the influence of the material, tooth type and cavity size on the results. The hypothesis was rejected at the 5% level. The analysis of the survival of the restorations was performed with the Kaplan–Meier method.
3.
Results
In the present study, a total of 701 posterior RC restorations were evaluated (Fig. 1). The date of the placement and the date of the failure were obtained from the dental records. Of the 701 restorations, 15 (2.1%) were determined to be unacceptable. The reasons for the failure included secondary caries, fracture of the restoration and endodontic treatment. In Table 3 failures for each of the 4 evaluated RCs after 10 years of clinical service are shown. All restorations given a “Charlie” rating were regarded as failed. Endodontic treatment was recorded as a reason for the failure of the restoration, and then the restoration was excluded from the following evaluation, because the USPHS criteria does not contain this clinical characteristic. Pulp protection was performed in 29 cases (n = 12 for Filtek Z250, n = 10 for Herculite XR, n = 2 for Gradia Direct Posterior and n = 5 for Renew) from which in 3 cases endodontic
Cumulave survival (%)
Molars
100 99 98 97 96 95 94 93 92 91 90 89 88 87 86 85
Filtek Z250 Herculite XR Gradia Direct Renew
0
5
6
7
8
9
10
11
12
Follow up me (years)
Fig. 2 – Cumulative survival rate of the four microhybrid composite resins.
treatment was necessary (n = 1 for Herculite XR, n = 1 for Gradia Direct Posterior and n = 1 for Renew). Fig. 2 shows the Kaplan–Meier survival curve for the 4 materials over 11 years of service. The overall success during the registration period was 97.86%. The failure rates for Filtek Z250 and Herculite XR were constant, 0.9% and 1.36%, respectively, after 11 years; however, an increasing failure rate was observed for Renew (7.81%) and Gradia Direct Posterior (8.57%), and these increased failure rates were significantly higher (p < 0.05) than the rates for Filtek Z250 and Herculite XR. A comparison between the RCs according to the USPHS criteria is presented in Table 4. A total of 349 (50.2%) restorations were accepted without changes and clinical remarks (A score), and in 346 (49.8%) cases, at least 1 deficiency was found (B or C score). The incidence of deficiencies (B and C codes) was 60% when the restorations were made with Filtek Z250, 72% with Renew, 81% with Herculite XR and 82% with Gradia Direct Posterior. The differences in the numbers of B and C codes between Filtek Z250 and Herculite XR (p = 0.015) or Filtek Z250 and Gradia Direct Posterior (p = 0.013) were statistically significant over the total observation period. Pearson’s Chi-Square test revealed a significantly higher rate of B and C scores in the color matching of Gradia Direct Posterior (p = 0.02) and in the fracture of Renew (p = 0.005); however, it should be mentioned that fractures were found in only 2 cases of the 61 Renew fillings. Considering the number of surfaces, in Filtek Z250, significantly more B and C scores were found in cases of 3 surface (MOD) restorations than in 2 surface (MO, OD) fillings (p < 0.001). Similar tendencies were observed in the other materials; however, these differences were not significant. Additionally, significantly greater marginal discolorations (p = 0.001) and anatomic form deficiencies (p = 0.02) were found in 3 surface RC fillings, independent of the type of material. The most frequent deficiency was the marginal discoloration (p = 0.027) among the
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
ARTICLE IN PRESS
DENTAL-2459; No. of Pages 8
5
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
Table 3 – Failed restorations by material during the 12-year monitoring period. Cause of failure
Materials FiltekZ250
Restoration fracture Secondary caries Endodontic treatment Total
1 2 0 3
HerculiteXR 0 3 1 4
Time of failure (years) Gradia 0 1 2 3
evaluated variables. Considering the type of tooth, restorations in premolars had similar survival rates as restorations in molars, although towards molars a growing trend could be observed.
4.
Discussion
In this retrospective clinical study, the long-term clinical performance of 4 microhybrid RC restoratives applied in Class II cavities was analyzed over an extended period of time. The main objective of the study was to observe whether microhybrid RCs with slightly different compositions of the resin matrix and different types, but similar sizes and volume fractions of filler particles showed distinct clinical performances. The number of long-term studies is low because they are time consuming and factors such as patient compliance, recall failure make these studies complicated. High drop-out rates and/or low number of participants have been a further weakness [4,33]. In the present study the recall rate was 83% after 10 years (9–11.5 years). It may be explained by the fact that these patients are mostly employees of the university. The main reason of drop-out was mostly the migration of involved students after their graduation. In contrast with a prospective, randomized clinical trial – for longevity analysis of different materials – a retrospective designed study may result in some deficiencies, such as the incomplete standardization of indications, treatment protocols or the missing baseline scoring. However, in the present study the involved practitioner was a university instructor, working according to high standards and mainly performing RC restorations for demonstrations for undergraduate and graduate education. Moreover, the selected patient group for this study acted as presentational cases (mostly dentists, general medicine colleagues, dental stuff, dental and general medicine students), therefore requiring an excellent implementation. In addition, this is a well-motivated patient group with high socioeconomic level, subjected to periodical examinations, oral hygiene and to instructions regarding dietary habits. The above mentioned facts may minimize the non material originating factors which influence the longevity of RC restorations, thus the study may have the possibility to focus on the failures raising from the differences of the 4 microhybrid RC materials. Considering the overall service time, this study reported a 97.86% survival rate of posterior Class II RC restorations. The average annual failure rate for the 4 RC materials was 0.52%, and it varied between 0.08 and 0.71%. Opdam et al. concluded
Renew 2 0 3 5
0-5
6
7
8
9
10
11
12
Total
1 0 3 4
1 1 0 2
1 2 1 4
0 1 0 1
0 0 0 0
0 1 1 2
0 1 0 1
0 0 1 1
3 6 6 15
that a randomized clinical trial has the advantage to standardize methods and calibrate the operators. Among others this can explain why the results of randomized clinical studies are often better than those of retrospective studies [27]. In our retrospective study one operator performed all the evaluated RC restorations with the maximal adherence to the indications and steps of the adhesive technique. It may explain the good results which are comparable with long-term controlled prospective studies. According to Frankenberg et al. [8] the overall success rate of RC restorations after 8 years is 98.5%, and 2.4% cumulative failure rate was reported by van Dijken et al. after 12 years [10]. However, our results show better survival rate than other retrospective studies (i.e. according to Opdam et al. the overall success rate is 82.2% after 10 years) [27] where difficulties arise in the standardization of the procedure and the calibration of the operators. Although, Baldissera et al. [19] reported 95% survival rate of 3 microhybrid RC restorations after 10 years in a retrospective study. They concluded, that good results may be explained by the single and skilled operator – thus the influence of the operator in the results is limited – and by the high socioeconomic status and good oral hygiene of patients, similarly as in our investigation. It is more likely that patient and operator factors, both favorable in this study, are the main factors influencing restoration longevity, while material properties may have a secondary role [25]. In a recent study, van de Sande et al. reported that the failure of restorations is significantly higher in patients at high caries risk [34]. In a 6-year prospective randomized study, van Dijken et al. showed that 63% of the recurrent caries lesions were found in high caries risk participants and the overall success rate was 88.1% [11]. Similar to the findings of other investigations, the main reasons for the failures in this study were secondary caries, fracture and endodontic treatment [1,2,5,9,26,27]; however, the occurrence of failures was low in the present study which may be explained by the above mentioned facts. Overall, the results showed that it is possible to place posterior RC restorations with considerable success and low failure rates, although a slightly increasing failure rate over the course of time was observed for 2 materials (8.37% for Gradia Direct Posterior and 7.81% for Renew). For example, when looking at the time interval, it was observed that Filtek Z250 (AFR 0.08%) and Herculite XR (AFR 0.1%) had a significantly better long-term survival. Baldissera et al. found similar good results with Herculite XR, presenting 0.3% AFR in their long-term retrospective study [19]. In contrast, Da Rosa Rodolpho et al. reported 1.5% AFR for Herculite XR after 10 years and a further increase (2.2%) was observed when the observation time was extended [1]. Unfortunately, there is a lack of long-term clinical studies with Renew or Filtek Z250, however our previous 5-year
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
6
ARTICLE IN PRESS
0.462 0.005 0.020 0.269 0.469 0.116 0.094 100/0 97.0/3.0# 80.3/19.7 77.0/33.0 90.2/9.8 85.2/14.8 100/0 0 2 0 0 0 0 0 0 12 14 6 9 0 61 59 49 47 55 52 61 “A” – Restorations with Alpha score – restoration without changes or clinical remarks. “B” – Restorations with Bravo score – restoration with changes that are clinically acceptable and without need for replacement. “C” – Restorations with Charlie score – restoration with major changes which require replacement of the restoration. ∗ Pearson’s Chi-Square and Fisher’s Exact test (p < 0.05). # Significantly differing variables.
97.0/3.0 100/0 79.0/21.0# 73.0/27.0 85.0/15.0 91.0/9.0 94.0/6.0 1 0 0 0 0 0 0 0 7 9 5 3 2 32 33 26 24 28 30 31 99.0/1.0 100/0 85.1/14.9 73.0/27.0 82.0/18.0 85.1/14.9 94.9/5.1 3 0 0 0 0 0 0 0 44 80 53 44 15 293 296 252 216 243 252 281 99.4/0.6 99.7/0.3 89.2/10.8 79.0/21.0 84.3/15.7 91.5/8.5 97.4/2.6 2 1 0 0 0 0 0 0 33 64 48 26 8 303 304 272 241 257 279 297 Secondary caries Fracture Color match Marginal discoloration Anatomic form Marginal integrity Surface roughness
A/(B + C) (%) A/(B + C) (%) C B A/(B + C) (%) C B A
B
C
A/(B + C) (%)
A
Herculite XR (n = 296) Filtek Z250 (n = 305)
Table 4 – Comparison between the composites according to the USPHS criteria.
A
Gradia Direct (n = 33)
A
B
C
Renew (n = 61)
p-value*
d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
retrospective evaluation of Class II restorations reported 98.8% success rate with Filtek Z250 [35]. Additionally, Filtek Z250 was commonly used to compare different properties of new materials in in vitro studies [36–38]. Increase in the annual failure rates of Gradia Direct Posterior and Renew were observed during the first five years of the observation period. In a 6-year prospective study van Dijken et al. reported 8.5% failure rate for Gradia Direct Posterior which is similar to our findings (8.37%), however the observation time is longer in the present study [39]. While the annual failure rate of Renew remained constant, the failure rate of Gradia Direct Posterior further increased after 11 years. Despite the fact that significant differences were found in the failure rates after 10 years, these materials had a long service time with clinically acceptable changes. Our results suggest that the follow-up time should be extended, as differences in the materials mostly emerge after more than 10 years. As one of the main reasons for restoration failure, fractures may indicate that Renew has lower long-term fracture resistance, most likely due to its lower E-modulus, which, in turn, is related to the slightly lower filler volume, which therefore increases the clinical effects of fatigue, compared to the other investigated materials. In vitro studies have shown that higher filler volumes increase the fracture toughness of restoratives, even after simulated occlusal loading [40,41]. On the other hand, lower filler volume implies higher monomer content. Because monomers are responsible for polymerization shrinkage, contraction stress may result in the fracture of the tooth or restoration [42]. The clinical data also indicated that other minor differences in material composition and properties may affect the clinical behavior of RC restorations. Gradia Direct Posterior showed a significantly greater change in color match; this could be explained by its larger average particle size, which may lead to an increased rate of extrinsic discoloration [43,44]. Furthermore, the amount of unreacted matrix monomers, photo-initiators and co-initiators has a considerable influence on the discoloration of the RC [45]. One of the limitations of our study is the relative low case number from Renew and Gradia Direct Posterior compared to the other materials. Increasing these case numbers may result in more reliable data. In accordance with other studies [3,7,19,27,46], our results showed that the amount of restored surfaces has a considerable effect on the quality of the restoration. Significantly more B codes were found in the MOD restoration cases made using Filtek Z250 than in the 2 surface restoration cases or in cases using the other materials. Independent of the materials, the anatomic form deficiencies in the cases of 3 surface restorations were higher levels than in 2 surface restorations. This could be explained by the larger RC surface, which wears under abrasive attacks, leading to a loss of material. Similarly to Gordan et al., marginal discoloration was the most frequent defect observed in the restorations, independent of the RC used [47]. In general, marginal quality decreases over time due to physiological and chemical interactions with the oral environment, and the onset of degradation could imply problems associated with the adhesive or the RC. Concerning the use of the adhesive system there are controversies in the literature. Some authors combine the RC material with the adhesive of the respective manufacturer
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
[8,11,39], however, others use only one type of adhesive for different RCs [19,27]. Demarco et al. and Lynch et al. in their review articles focused on the type of adhesives they preferred to use, instead of focusing on the relevance of the combination of RC material with the adhesive of the respective manufacturer [25,48]. In the present study one universal total-etch adhesive system was used for all of the 4 materials. This may standardize the adhesive procedure and exclude the changes which may be originated from the different adhesive systems, therefore, a direct comparison between the differences of the microhybrid RCs may be made. There are inconsistent findings concerning the effect of tooth type. Some articles have reported that restorations placed in premolars exhibited significantly better survival rates than those placed in molars [1,3,7,8,46,28]. This is suspected to be due to the greater occlusal forces on molar restorations compared with those in premolars. Another possible explanation is the decreased access to the operating field when restoring molars. However, our results cannot confirm these findings. Similar to the findings of Aoyama et al. [24], our results showed no significant effect of tooth type on the longevity or quality of posterior RC restorations.
5.
Conclusions
Within the limitations of this retrospective study, the following conclusions can be drawn: • All 4 microhybrid resin composites showed acceptable clinical durability in Class II restorations during the 10-year follow-up period, with an overall survival rate of 97.9%. • When considering the differences according to the USPHS criteria, higher rates of B and C codes were observed in the Renew (fracture) and Gradia Direct Posterior (color match) (p < 0.05) restorations; therefore, the null hypothesis was rejected.
Acknowledgements We would like to thank Professor Dr Ralf Schulze (Johannes Gutenberg-University of Mainz, Germany) for his valuable advices in this research work. This work was supported by PTE ÁOK-KA-2013/5 and a 2013/26 Research Grant.
references
[1] Da Rosa Rodolpho PA, Donassollo TA, Cenci MS, Loguércio AD, Moraes RR, Bronkhorst EM, et al. 22-year clinical evaluation of the performance of two posterior composites with different filler characteristics. Dent Mater 2011;27:955–63. [2] Opdam NJM, Bronkhorst EM, Loomans BA, Hujsmans MC. 12-year survival of composite vs. amalgam restorations. J Dent Res 2010;89:1063–7. [3] Pallesen U, van Dijken JWV, Halken J, Hallosten AL, Höigaard R. Longevity of posterior resin composite restorations in permanent teeth in Public Dental Health Service: a prospective 8 years follow up. J Dent 2013;41:297– 306.
7
[4] Manhart J, Chen H, Hamm G, Hickel R. Buonocore memorial lecture. Review of the clinical survival of direct and indirect restorations in posterior teeth of the permanent dentition. Oper Dent 2004;29:481–508. [5] Bernardo M, Luis H, Martin MD, Leroux BG, Rue T, Leitao J, et al. Survival and reason for failure of amalgam versus composite posterior restorations placed in a randomized clinical trial. J Am Dent Assoc 2007;138: 775–83. [6] Burke FJ, Lucarotti PS. How long do direct restorations placed within the general dental services in England and Wales survive? Br Dent J 2009;206:E2. [7] Da Rosa Rodolpho PA, Cenci MS, Donassollo TA, Loguercio AD, Demarco FF. A clinical evaluation of posterior composite restorations: 17-year findings. J Dent 2006;34: 427–35. [8] Frankenberger R, Reinelt C, Krämer N. Nanohybrid vs. fine hybrid composite in extended class II cavities: 8-year results. Clin Oral Investig 2014;18:125–37. [9] Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior dental restorations and reasons for failure. Eur J Oral Sci 2012;120:539–48. [10] van Dijken JWV. Durability of resin composite restorations in high C-factor cavities: A 12-year follow-up. J Dent 2010;38:469–74. [11] van Dijken JWV, Pallesen U. A six-year prospective randomized study of a nano-hybrid and a conventional hybrid resin composite in Class II restorations. Dent Mater 2013;29:191–8. [12] Beun S, Glorieux T, Devaux J, Vreven J, Leloup G. Characterization of nanofilled compared to universal and microfilled composites. Dent Mater 2007;23:51–9. [13] Blackham JT, Vandewalle KS, Lien W. Properties of hybrid resin composite systems containing prepolymerized filler particles. Oper Dent 2009;34(6):697–702. [14] de Moraes RR, Goncalves LS, Lancellotti AC, Consani S, Correr-Sobrinho L, Sinhoreti MA. Nanohybrid resin composites: nanofiller loaded materials or traditional microhybrid resins? Oper Dent 2009;34:551–7. [15] Lohbauer U, Frankenberger R, Kramer N, Petschelt A. Strength and fatigue performance versus filler fraction of different types of direct dental restoratives. J Biomed Mater Res B Appl Biomater 2006;76:114–20. [16] Venturini D, Cenci MS, Demarco FF, Camacho GB, Powers JM. Effect of polishing techniques and time on surface roughness, hardness and microleakage of resin composite restorations. Oper Dent 2006;31:11–7. [17] Cenci MS, Lund RG, Pereira CL, de Carvalho RM, Demarco FF. In vivo and in vitro evaluation of Class II composite resin restorations with different matrix systems. J Adhes Dent 2006;8:127–32. [18] Palaniappan S, Bharadwaj D, Mattar DL, Peumans M, Van Meerbeek B, Lambrechts P. Nanofilled and microhybrid composite restorations: five-year clinical wear performances. Dent Mater 2011;27:692–700. [19] Baldissera RA, Corrêa MB, Schuch HS, Collares K, Nascimento GG, Jardim PS, et al. Are there universal restorative composites for anterior and posterior teeth? J Dent 2013;41:1027–35. [20] Kiremitci A, Alpaslan T, Gurgan S. Six-year clinical evaluation of packable composite restorations. Oper Dent 2009;34:11–7. [21] Kuper NK, Opdam NJM, Bronkhorst EM, Hujsmans MCDNJM. The influence of approximal restoration extension on the development of secondary caries. J Dent 2012;40: 241–7. [22] Padr R, Cenci MS, Donassollo TA, Loguercio AD, Demarco FF. A clinical evaluation of posterior composite restorations: 17-year findings. J Dent 2006;134:427–35.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
DENTAL-2459; No. of Pages 8
8
ARTICLE IN PRESS d e n t a l m a t e r i a l s x x x ( 2 0 1 4 ) xxx–xxx
[23] van Nieuwenhuysen JP, D’Hoore W, Carvalho J, Qvist V. Long-term evaluation of extensive restorations in permanent teeth. J Dent 2003;31:395–405. [24] Aoyama T, Aida J, Takehara J, Morita M. Factors associated with the longevity of restorations in posterior teeth. J Dent Health 2008;58:16–24. [25] Demarco FF, Correa MB, Cenci MS, Moraes RR, Opdam NJM. Longevity of posterior composite restorations: not only a matter of materials. Dent Mater 2012;28:87–101. [26] Lindberg A, van Dijken JW, Lindberg M. Nine-year evaluation of a polyacid-modified resin composite/resin composite open sandwich technique in Class II cavities. J Dent 2007;35:124–9. [27] Opdam NJM, Bronkhorst EM, Rooters JM, Loomans BAC. A retrospective clinical study on longevity of posterior composite and amalgam restorations. Dent Mater, 2007;23:2–8. [28] Pallesen U, Qvist V. Composite resin fillings and inlays. An 11-year evaluation. Clin Oral Investig 2003;7:71–9. [29] Weaver WS, Blank LW, Pelleu Jr GB. A visible light activated resin cured through tooth structure. Gen Dent 1988;36:236–7. [30] Ryge G, Snyder M. Evaluating the clinical quality of restorations. J Am Dent Assoc 1973;87:369–77. [31] Ryge G. Clinical criteria. Int Dent J 1980;30:347–58. [32] European Commission. European guidelines on radiation protection in dental radiology. The safe use of radiographs in dental practice. Radiat Prot 2004;136. [33] Brunthaler A, Konig F, Lucas T, Sperr W, Schedle A. Longevity of direct resin composite restorations in posterior teeth. Clin Oral Investig 2003;7:63–70. [34] van de Sande FH, Opdam NJ, Rodolpho PA, Corrêa MB, Demarco FF, Cenci MS. Patient risk factors’ influence on survival of posterior composites. J Dent Res 2013;92:785–838. [35] Lempel E, Szalma J, Jeges S, Kende D, Krajczár K, Nagy ÁK, et al. Retrospective study of direct composite restorations according to the USPHS criteria. Fogorvosi Szle 2012;105:47–52. [36] Lempel E, Czibulya Zs, Kunsági-Máté S, Szalma J, Sümegi B, Böddi K. Quantification of conversion degree and monomer elution from dental composite using HPLC and micro-Raman Spectroscopy. Chromatographia 2014;77:1137–44.
[37] Garoushi S, Säilynoja E, Vallittu PK, Lassila L. Physical properties and depth of cure of a new short fiber reinforced composite. Dent Mater 2013;29:835–41. [38] Watanabe H, Khera SC, Vargas MA, Qian F. Fracture toughness comparison of six resin composites. Dent Mater 2008;24:418–25. [39] van Dijken JWV. A 6-year prospective evaluation of a one-step HEMA-free self etching adhesive in Class II restorations. Dent Mater 2013;29:1116–22. [40] Ferracane JL, Condon JR. In vitro evaluation of the marginal degradation of dental composites under simulated occlusal loading. Dent Mater 1999;15:262–7. [41] Ilie N, Hickel R. Investigations on mechanical behavior of dental composites. Clin Oral Investig 2009;13:427–38. [42] Meredith N, Setchell DJ. In vitro measurement of cuspal strain and displacement in composite restored teeth. J Dent 1997;25:331–7. [43] Nasim I, Neelakantan P, Sujeer R, Subbarao CV. Color stability of microfilled, microhybrid and nanocomposite resins—an in vitro study. J Dent 2010;38:137–42. [44] Yu B, Lim HN, Lee YK. Influence of nano- and micro-filler proportions on the optical property stability of experimental dental resin composites. Mater Des 2010;31: 4719–24. [45] Schneider LFJ, Pfeifer CSC, Consani S, Prahl SA, Ferracane JL. Influence of photoinitiator type on the rate of polymerization, degree of conversion, hardness and yellowing of dental resin composites. Dent Mater 2008;24:1169–77. [46] Opdam NJM, Bronkhorst EM, Roeters JM, Loomans BA. Longevity and reasons for failure of sandwich and total-etch posterior composite resin restorations. J Adhes Dent 2007;9:469–75. [47] Gordan VV, Garvan CW, Blaser PK, Mondragon E, Mjör IA. A long-term evaluation of alternative treatments to replacement of resin-based composite restorations: results of a seven-year study. J Am Dent Assoc 2009;140: 1476–84. [48] Lynch CD, Opdam NJ, Hickel R, Brunton PA, Gurgan S, Kakaboura A, et al. Guidance on posterior resin composites: Academy of Operative Dentistry – European Section. J Dent 2014;42:377–83.
Please cite this article in press as: Lempel E, et al. Retrospective evaluation of posterior direct composite restorations: 10-Year findings. Dent Mater (2014), http://dx.doi.org/10.1016/j.dental.2014.11.001
