DOI: 10.1111/ipd.12157
Risk factors for secondary caries in direct composite restorations in primary teeth ISABEL METZ1, KATRIN ROTHMAIER1, VINAY PITCHIKA1, ALEXANDER CRISPIN2, 1 1 € € REINHARD HICKEL1, FRANKLIN GARCIA-GODOY3, KATHARINA BUCHER & JAN KUHNISCH 1
Department of Conservative Dentistry, Ludwig-Maximilians University Munich, Munich, Germany, 2Institute for Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians University Munich, Munich, Germany, and 3Department of Bioscience Research, University of Tennessee Health Science Center, Memphis, TN, USA
International Journal of Paediatric Dentistry 2015 Background. Secondary caries or caries adjacent
to restorations is the most frequent reason for replacement of dental restorations. Though, limited data is available on variables influencing the development of secondary caries in primary teeth. Aim. To investigate risk factors for the development of secondary caries adjacent to direct composite restorations in primary teeth. Design. For this retrospective study, data of 2417 composite restorations, which were placed due to primary carious lesions, were considered. A total of 212 restorations failed due to secondary caries within a maximum observation period of 8 years. A control group was randomly selected. Mann–Whitney U-test, binomial logistic regression with backward
Introduction
Caries adjacent to restorations or secondary caries is defined as a carious lesion occurring at the cavity margins of dental restorations1 and is one of the most frequent reasons for filling replacement in primary2 and permanent2–4 teeth. Some controversy exists about the choice of restorative materials having an influence on the progression or inhibition of caries. Some studies have shown that, in the permanent dentition composite fillings are more frequently associated with the development of secondary caries than restorations performed with amalgam2,4,5, compomer, and glass ionomer cement6. In contrast, some studies did Correspondence to: Jan K€ uhnisch, Ludwig-Maximilians Universit€ at M€ unchen, Poliklinik f€ ur Zahnerhaltung und Parodontologie, Goethestraße 70, 80336 M€ unchen, Germany. E-mail: [email protected]
elimination and Cox regression with frailty model were performed (P < 0.05). Results. The overall caries experience amounted to 6.3 dmft and 13.3 dmfs. 72.5% of restorations failed within the first 2 years. Older children and children from families with a higher socio-economic status showed a lower risk for secondary caries. Further, the dentist and the adhesive had a significant influence on the longevity. Posterior restorations had a higher risk to fail in comparison with anterior restorations. Conclusions. Within the limitation of this study, it is concluded that the development of secondary caries is influenced by several factors. Nevertheless, the secondary caries rate was found to be relatively low in this high-risk population.
not find any significant influence of the material used or even showed an adverse effect7. For the primary dentition, similar outcomes can be found in the literature. Different working groups documented a higher8, lower9, or equal risk10 for secondary caries for composite and compomer materials. For the permanent dentition, the influential factors on the longevity of composite restorations have been investigated thoroughly. The most significant reason for the occurrence of secondary caries appeared to be the patientrelated caries risk5 also elevating the number of pre-existing restorations2–4. In addition, patients’ age3, tooth type4, cavity size2,4, preparation, and depth3 as well as the location of the restoration in the maxilla or mandible4 may have an influence on the development of secondary caries. Although these factors were significant for the permanent dentition, only few studies elucidated the reasons for secondary caries in the primary dentition. Until now, sparse data show
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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that the number of filled surfaces in composite fillings had an influence on caries progression adjacent to restoration margins10. This further implies that investigations regarding the factors which are related to secondary caries in the primary dentition are needed. Therefore, the aim of this retrospective study was to identify potential risk factors for the development of secondary caries of composite fillings. The null hypothesis was that these variables will not have a significant influence on caries formation adjacent to restoration margins (null hypothesis). Materials and methods
This retrospective investigation was conducted in accordance with the Declaration of Helsinki and the ISPOR Task Force on Retrospective Databases11. Approval by the Ethics Committee of the Medical Faculty of the Ludwig-Maximilians University of Munich had been retrieved prior to the investigation (Project number: 030-13). Study population, inclusion, and exclusion criteria For this retrospective survey data of children aged 1–13 years (mean 6.6) who had been treated at the Department of Paediatric Dentistry between January 2004 and December 2012 were considered. Out of this patient group, all direct composite fillings on primary teeth that were placed due to primary caries and without sedation or general anaesthesia were included into the data set. Data were not admitted if the dental treatment was associated with other reasons than caries, for example, fillings due to trauma, hypomineralization, or hypoplasia of tooth structure. Also, composite restorations prior to stainless steel crowns were excluded. The data were recorded blinded according to a standardized procedure. With respect to these criteria, 2417 composite restorations were identified. For each case, relevant patient-related data (age, gender, health insurance status, and dmft index at the first appointment12) were recorded. Regarding health insurance status, it has to be noted that in Germany, a private health
insurance is linked to a higher socio-economic status of the insured parent represented by an above-average income and mostly university education. Furthermore, restoration- (Black’s classification, number of filled surfaces) and treatment-related factors (use of dental dam, adhesive and composite material, and operating dentist) were included. In addition, information from the recall appointments, for example, dichotomized assessment (sufficient, insufficient) of the filling quality according to the FDI criteria1,13, reasons of insufficiency (secondary caries, loss of retention, gap at the margin, fracture, total loss, tooth fracture, allergic reaction, and others), performed extraction, and the restoration survival time were collected. Treatment protocol Each patient was treated according to the same treatment protocol, which was individualized and adapted to every patients0 needs. Behaviour management techniques, for example, tell-show-do, systematic desensitization, and positive reinforcement were used appropriately to enhance the child’s cooperation. Following the protocol, after retrieving detailed medical history, dental cleaning was performed prior to a thorough clinical examination. Standardized visual caries examination14 was used for caries diagnostics, and bitewing radiographs were performed according to the prescription guidelines for dental radiographs, if indicated15,16. All diagnoses were registered in detail, and caries-related findings were used to calculate the dmft index12. Dentine caries was excavated and restored with a composite restoration. The operating procedure consisted of the following steps. Before beginning with the dental treatment, local anaesthesia was recommended if necessary to provide appropriate analgesia. To ensure an adequate isolation, either dental dam in split dam technique or cotton roll was used. In the first step of caries excavation, the access cavity was prepared minimally invasive using high-speed diamond-coated burs (Gebr. Brassler GmbH & Co. KG, Lemgo, Germany) with water
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Risk factors for secondary caries
cooling. Subsequently, deep caries lesions were excavated with low-speed tungsten carbide burs (Gebr. Brassler GmbH & Co. KG), hand excavators (Hu Friedy, Rotterdam, Netherlands) and/or the self-limiting burs SmartPrep (SS White, Lakewood, NJ, USA), SmartPrepII (SS White), or PolyBur P1 (Komet Dental Gebr. Brasseler GmbH & Co. KG). The excavation was considered completed when the remaining dentine was hard/solid. In case of an active and deep caries lesion, a calcium hydroxide liner (Kerr Life, Kerr Corporation, Orange, CA, USA) was applied. If the carious process involved the pulp, a vital pulpotomy was performed17. Cavity margins were cleaned conventionally until sound hard tissue remained to achieve optimal prerequisites for the marginal seal. For proximal cavities, a retainerless matrix system (AutoMatrix, Dentsply De Trey, York, PA, USA) and wedge were placed. Then the cavity was conditioned either using total etch with 37.5% phosphoric acid (Total Etch, Ivoclar Vivadent, Schaan, Liechtenstein) for ~10 seconds and total bond (Syntac Classic, Ivoclar Vivadent, Schaan, Liechtenstein) or a self-etching adhesive (Clearfil SE Bond, Kurarary Europe, Frankfurt, Germany). Following to this, the cavity was filled with a flowable composite (Tetric (Evo) Flow, Ivoclar Vivadent, Schaan, Liechtenstein) and/or a (nano-) hybrid composite material (Tetric (Evo) Ceram, Ivoclar Vivadent, Schaan, Liechtenstein). Every increment did not exceed more than 2 mm of thickness. The minimum cumulative polymerization time for each restoration amounted to 20 s. For polishing and finishing, appropriate rotating rubber polishers, for example, Enhance (Dentsply Caulk, Milford, DE, USA), were used. All patients were recommended to be included into an intensified preventive programme with intervals dependant on their caries risk, usually from 3 to 4 months. These appointments included dental cleaning and application of fluoride varnish as well as an individualized oral hygiene motivation and instruction as well as nutritional advice for patients and caretakers. In general, all fillings were assessed retrospectively according the FDI criteria for evaluation of direct restorations1,13. In case of any insufficiency, for example, caries with cavitation and undermining caries, deep caries, or
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exposed dentine (that was not accessible for repair of restoration)1, fillings were repaired or replaced immediately or at the next appointment. The evaluators were the same clinicians, who placed the restorations, and, additionally, they had no knowledge about participating in a scientific study. All operating dentists followed a conservative and critical diagnostic model. A cavity at the margin of a restoration was considered to be secondary caries, but a discoloured margin was not. The clinical diagnosis of a secondary caries is a ‘soft criteria’ and may vary between dentists1,13. Eight fully graduated dentists performed all treatments. Operator 1, 2, and 5 are specialists for paediatric dentistry and had more than 5 years of clinical experience at the beginning of the observation time. In contrast, the operators 3, 4, 6, 7, and 8 had little clinical experience at the beginning and increased their skills over the time. The operators 1–8 also evaluated all of the restorations. Statistical analysis The study-related data were entered in a spreadsheet programme (Microsoft Office Excel 2007, Unterschleissheim, Germany) and analysed using SPSS software, version 21.0 (SPSS Inc., an IBM Company, Chicago, IL, USA) and R software (version 3.0.2, R Development Core Team, Vienna, Austria). To calculate the correct survival time for each composite restoration, the observation period was determined as the difference between the date on which the filling was placed and the latest appointment on which the filling was assessed as sufficient. If the filling was sufficient but the tooth was extracted or exfoliated, the survival of the restoration ended at the date of extraction or at the last date when the tooth was evaluated. Each restoration was observed until the respective date. Five hundred and seven of 2417 restorations had no follow-up and therefore a survival time of 0 days. The remaining 1910 restorations had a survival time of >1 day. Years were expressed by days, with 365 days counting as a full year, 730 days as 2 years
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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and so on. In cases of a new independent restoration on a tooth at a different surface, the monitored restoration was not considered as a failure. The maximum and mean observation time was calculated. For calculation, two groups were defined. According to the dental records, a total of 212 restorations failed due to secondary caries and were used as one group. For the control group, 212 intact fillings without failures were selected randomly from the remaining data set to have a 1:1 comparison. Mann–Whitney Utest was performed to calculate the significant differences between the secondary caries group and the control group. Hazard ratios for the failure of the composite restorations were calculated using binomial logistic regression with backward elimination model. The eliminated factors from this model were also presented in the results table to provide information on those variables. Additionally, Cox regression was performed using frailty model to adjust for
the clustering of the data due to the presence of multiple fillings in some patients. To avoid bias from random sampling of control population, we further repeated binomial logistic regression and Cox regression by entering all the controls into the models. The two-tailed significance level for all analyses was set at P < 0.05. Results
A total of 2417 composite restorations matched the inclusion criteria. Whereas in 8.8% (212/ 2417) of cases, fillings became insufficient due to secondary caries; another 8.2% (199/2417) were lost due to other reasons over the observation (Figs 1 and 2). The maximum observation period was 8 years, while the mean observation time was 1.9 years (SD 1, 1 years) for the 1:1 control sampling and 1.1 years (SD 1.3 years) for the 1:all control sampling. 72.6% (154/212) of the secondary caries lesions were
Fig. 1. Number of healthy composite restoration and those with secondary caries in relation to the time point of diagnosis. Overall restorations with secondary caries (n = 212).
Fig. 2. Reasons for composite restoration failure during the observation period. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Risk factors for secondary caries
diagnosed during the first 2 years after application of the composite restorations (Fig. 1). The paediatric patients in both groups had a similar caries experience (Table 1). In Table 2, patient- and restoration-related information is given. In logistic regression models, the patient’s age, health insurance status, and the location of the restorations according to Black0 s classification were tested to have a significant influence on the development of secondary caries. The risk for a composite restoration to become insufficient due to secondary caries decreased continuously with increasing age, beginning from age 3. A private health insurance status reduced further the risk for establishing a secondary caries. Most frequently, secondary caries was diagnosed in primary molars (Class I–II). In Table 3, treatment-related data are listed, and two variables were significant in logistic regression models. The use of phosphoric acid in combination with a total bond adhesive showed higher risk for failure compared to a self-etching adhesive. The analysis of the operating dentists showed heterogeneous results. Whereas some operators treated their patients with a reduced risk of getting secondary caries, for others, the opposite results were registered. Discussion
The present retrospective study was conducted to evaluate variables with potential influence on the development of secondary caries adjacent to composite restorations in
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primary teeth. Basic characteristics of the study population showed a high caries risk represented by a high mean caries experience of 6.3 caries affect teeth, which is approximately three times higher compared to the mean caries experience of this age group in Bavaria18 and is representing the typical situation of children with early childhood caries. A major influencing factor in this investigation was secondary caries, which exposed to be the most frequent reason for an insufficient filling in primary teeth. This finding was in line with several other studies2–4,19. In comparison to other clinical trials, the frequency of secondary caries development appeared to be rather low in this investigation, because failures of fillings due to secondary caries were lower than 10% over the maximum observation period of 8 years. A major reason for this finding could be the intensified preventive care during a clinical trial that was performed; this may have influenced the oral health positively and reduced the risk for secondary caries in this caries risk cohort. Re-evaluation and demonstration of proper oral hygiene techniques within the dental visits increase the probability of better oral health20; therefore, it has to be safeguarded by the parents. By practicing and rebrushing their children’s teeth, parents are able to ensure a good quality of oral hygiene and extend the longevity of their children’s restorations. Also, it is in the families’ responsibility to control drinking and eating habits to ensure a tooth-friendly nutrition. Therefore, our intensified preventive intervention
Table 1. Caries experience of the patients at the first appointment.
Caries experience at the 1st appointment
Patients with restorations with secondary caries (SD)
Patients with control restorations (SD)
Overall patients Mean (SD)
dmft dt mt ft dmfs ds ms fs
6.5 4.8 0.3 1.5 13.9 8.5 1.3 4.1
6.1 4.6 0.4 1.2 12.7 8.1 1.4 3.2
6.3 4.7 0.3 1.3 13.3 8.3 1.4 3.7
(3.6) (3.5) (0.9) (2.2) (12.3) (9.5) (3.9) (7.0)
SD, standard deviation. Bold: P < 0.05, Mann–Whitney U-test. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
(3.8) (3.5) (1.2) (2.2) (11.0) (8.6) (4.5) (6.1)
(3.7) (3.5) (1.0) (2.2) (11.7) (9.1) (4.2) (6.6)
15.1 33.0 33.0 15.1 3.8 42.5 57.5 99.5 – 0.5 25.0 58.5 9.4 1.4 5.7 33.0 55.7 8.0 3.3
90 122 211 – 1 53 124 20 3 12 70 118 17 7
%
32 70 70 32 8
n
HR, hazard ratio. Bold: P < 0.05 using Cox regression model.
Patient’s age (in years) 0–3 4–5 6–7 8–9 10–14 Patient’s gender Female Male Patient’s health insurance status National health ins. Self-financing Private health ins. Black’s classification Class I Class II Class III Class IV Class V Number of restored tooth surfaces 1 2 3 >4
Patient- and restoration-related variable
Restorations with secondary caries
64 124 15 9
34 130 19 13 16
192 – 20
95 117
15 52 57 57 31
n
30.2 58.5 7.1 4.2
16.0 61.3 9.0 6.1 7.5
90.6 – 9.4
44.8 55.2
7.1 24.5 26.9 26.9 14.6
%
Control restorations
1.0 0.9 1.8 3.2
1.0 1.2 0.8 0.1 0.4
1.0 – 0.2
1.0 1.2
1.0 0.5 0.4 0.2 0.0
OR
1.0 0.9 0.9 0.9 0.7 1.0 1.1 1.0 – 0.1 1.0 1.2 1.4 0.5 0.8 1.0 0.8 1.0 1.4
– 0.8–1.9 – – 0.1–0.6 – 0.7–2.1 0.3–1.8 0.0–0.6 0.2–1.0 – 0.5–1.7 0.6–5.2 0.5–19.3
HR
– 0.5–1.3 0.5–2.1 0.5–4.1
– 0.7–2.1 0.7–2.9 0.1–2.1 0.4–1.6
– – 0.0–0.8
– 0.7–1.6
– 0.4–2.4 0.5–1.5 0.5–1.7 0.4–1.3
95% CI
Cox regression model/Frailty model
– 0.2–1.0 0.2–1.0 0.1–0.4 0.1–0.6
95% CI
Logistic regression analysis
1:1 control sampling
Table 2. Descriptive data and results from the regression models of patient- and restoration-related variables.
645 1111 142 57
346 1151 206 71 181
1734 82 139
909 1046
136 459 625 521 214
n
33.0 56.8 7.3 2.9
17.7 58.9 10.5 3.6 9.3
88.7 4.2 7.1
46.5 53.5
7.0 23.5 32.0 26.6 10.9
%
Control restorations
1.0 1.1 1.2 1.9
1.0 1.2 1.1 0.7 0.5
1.0 0.4 0.1
1.0 1.2
1.0 0.7 0.5 0.5 0.5
OR
– 0.7–1.8 0.6–2.2 0.7–4.9
– 0.9–1.7 0.7–1.9 0.2–2.1 0.2–0.9
– 0.1–1.2 0.0–0.6
– 0.9–1.5
– 0.4–1.0 0.3–0.8 0.3–0.8 0.2–1.0
95% CI
Logistic regression analysis
1: all control sampling
1.0 1.1 1.2 2.6
1.0 1.0 0.9 0.4 0.4
1.0 0.5 0.1
1.0 1.2
1.0 0.8 0.7 0.6 0.6
HR
– 0.7–1.8 0.6–2.5 0.9–7.7
– 0.6–1.6 0.5–1.8 0.1–1.5 0.2–0.8
– 0.1–1.9 0.0–0.6
– 0.8–1.9
– 0.5–1.5 0.4–1.2 0.3–12 0.2–1.5
95% CI
Cox regression model/Frailty model
6 I. Metz et al.
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
DOI: 10.1111/ipd.12157
Risk factors for secondary caries in direct composite restorations in primary teeth ISABEL METZ1, KATRIN ROTHMAIER1, VINAY PITCHIKA1, ALEXANDER CRISPIN2, 1 1 € € REINHARD HICKEL1, FRANKLIN GARCIA-GODOY3, KATHARINA BUCHER & JAN KUHNISCH 1
Department of Conservative Dentistry, Ludwig-Maximilians University Munich, Munich, Germany, 2Institute for Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians University Munich, Munich, Germany, and 3Department of Bioscience Research, University of Tennessee Health Science Center, Memphis, TN, USA
International Journal of Paediatric Dentistry 2015 Background. Secondary caries or caries adjacent
to restorations is the most frequent reason for replacement of dental restorations. Though, limited data is available on variables influencing the development of secondary caries in primary teeth. Aim. To investigate risk factors for the development of secondary caries adjacent to direct composite restorations in primary teeth. Design. For this retrospective study, data of 2417 composite restorations, which were placed due to primary carious lesions, were considered. A total of 212 restorations failed due to secondary caries within a maximum observation period of 8 years. A control group was randomly selected. Mann–Whitney U-test, binomial logistic regression with backward
Introduction
Caries adjacent to restorations or secondary caries is defined as a carious lesion occurring at the cavity margins of dental restorations1 and is one of the most frequent reasons for filling replacement in primary2 and permanent2–4 teeth. Some controversy exists about the choice of restorative materials having an influence on the progression or inhibition of caries. Some studies have shown that, in the permanent dentition composite fillings are more frequently associated with the development of secondary caries than restorations performed with amalgam2,4,5, compomer, and glass ionomer cement6. In contrast, some studies did Correspondence to: Jan K€ uhnisch, Ludwig-Maximilians Universit€ at M€ unchen, Poliklinik f€ ur Zahnerhaltung und Parodontologie, Goethestraße 70, 80336 M€ unchen, Germany. E-mail: [email protected]
elimination and Cox regression with frailty model were performed (P < 0.05). Results. The overall caries experience amounted to 6.3 dmft and 13.3 dmfs. 72.5% of restorations failed within the first 2 years. Older children and children from families with a higher socio-economic status showed a lower risk for secondary caries. Further, the dentist and the adhesive had a significant influence on the longevity. Posterior restorations had a higher risk to fail in comparison with anterior restorations. Conclusions. Within the limitation of this study, it is concluded that the development of secondary caries is influenced by several factors. Nevertheless, the secondary caries rate was found to be relatively low in this high-risk population.
not find any significant influence of the material used or even showed an adverse effect7. For the primary dentition, similar outcomes can be found in the literature. Different working groups documented a higher8, lower9, or equal risk10 for secondary caries for composite and compomer materials. For the permanent dentition, the influential factors on the longevity of composite restorations have been investigated thoroughly. The most significant reason for the occurrence of secondary caries appeared to be the patientrelated caries risk5 also elevating the number of pre-existing restorations2–4. In addition, patients’ age3, tooth type4, cavity size2,4, preparation, and depth3 as well as the location of the restoration in the maxilla or mandible4 may have an influence on the development of secondary caries. Although these factors were significant for the permanent dentition, only few studies elucidated the reasons for secondary caries in the primary dentition. Until now, sparse data show
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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includes oral hygiene instructions, motivations, and nutritional advice for the patients as well as for their parents. The analyses showed further that, especially the first 2 years after placing the filling turned out to be the most critical time for secondary caries development in primary teeth. This finding is inverse to a recently published meta-analyses from Opdam et al.21; the authors showed an increasing onset of secondary caries especially in the later years of observation in permanent teeth. These contrary findings can be explained by the high caries risk of children affected by early childhood caries22. In children whose families do not change their nutritional behaviour and oral hygiene procedures, a rapid initiation of new caries lesions, the progression of existing non-cavitated caries lesions, and/or the onset of secondary caries within a short period of time after restoration placement can be observed. The documented early onset of secondary caries in this study indicates that some patients obviously do not benefit from the intensified preventive care and, therefore, will be affected by a caries reversal shortly after primary rehabilitation. Contrary to this situation, adult persons may follow preventive advice with higher probability and, mostly, secondary caries will be diagnosed in later years. Another important aspect for the registered early onset of secondary caries in our study might be the challenging situation to treat young children without using the option of general anaesthesia. A limited ability of the child for cooperation and the requirement to perform dental procedure in a minimum of time while endeavouring to safeguard sensitive treatment protocols can reduce the quality of a restoration. Therefore, the early onset of secondary caries might indicate that the restorations had insufficiencies already present immediately after placement. This might be possible as all restorations of this study were performed in an outpatient dental setting and no sedation technique or general anaesthesia was used. This investigation aimed to identify potential risk factors for the development of secondary caries of composite fillings in primary teeth. An influential patient-related variable
seems to be the paediatric patient’s age. Older children (age > 3 years) have obviously a lower risk for secondary caries than younger patients. This is naturally linked to the difficulties treating young children due to a limited ability of the younger child to cooperate. Also, eventually, treatment of the more uncooperative child will lead to compromises in treatment and might further affect the restoration quality. If such errors occur, a rapid caries development could be observed, which result in a shorter survival time. This concerns all filling materials, but especially those which are sensitive to time, moisture, and a setting time over some few minutes. The analysis of the health insurance status illustrated that the hazard for secondary caries was significantly reduced when the patient’s parents had a private health status. This insurance status is linked to a higher socioeconomic status, above-average income, and, mostly, university education of the parents and has to be kept in mind while interpreting these results. The association of those factors and caries development in children was also confirmed in other studies23. A filling-related and significant variable was the type of cavity. Composites on the occlusal (Class I) and proximal surfaces (Class II) of primary molars showed a higher risk compared to all other types of cavitations. In detail, similar to the result from a previous study10,24, Class II restorations had a (slightly) higher risk compared to Class I restorations. In addition, a greater filling size (number of restored tooth surfaces) tended to have a higher risk for secondary caries. This variable was not as significant, but several authors had reported lower survival rates for multisurfaced restorations in primary teeth10,24 before. The overall high number of cases for Class I and II indicates that posterior teeth are more susceptible for (secondary) caries in primary dentition compared to anterior teeth. A possible reason could be the specific anatomy of primary molars with deep fissures and extensive proximal surfaces. An excellent plaque removal is challenging for these teeth, and it has been shown that significantly more dental plaque was found on molars in
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Risk factors for secondary caries
contrast to anterior teeth prior and immediately after tooth brushing25. Analysing the treatment-related variables, the operating dentist turned out to have a significant impact like Opdam et al.26 found for permanent dentition. In this study, all operators used similar materials and treatment protocols. Nevertheless, the outcome was heterogeneous. An explanation could be that the professional experiences and skills of the dentist varied and might have influenced the quality and longevity of the restoration. The use of a self-etching adhesive reduced the risk for failure in comparison with phosphoric acid in combination with a total bond adhesive. This is in line with Koshiro et al.27, who showed a higher resistant to degradation of the adhesive interface produced by the self-etch system compared to the adhesive interface produced by the etch-and-rinse adhesive. In addition, a reduced application time, which is relevant especially in paediatric patients, might affect the restorations quality and longevity. Dental dam had no significant influence in both regression analyses. But this result might be owed by the low number of cases and, therefore, the reduced statistical strength of this variable. Nevertheless, dental dam may have the potential to affect the quality of a restoration in a positive way and lead to a protective effect regarding the risk of secondary caries. Based on the results, the null hypothesis was rejected as several variables turned out to have significant effects. This study was a retrospective analysis of patient’s records. So far, only a limited number of studies analysing composite restorations in primary teeth is available10,19,24,28,29. The strength of this investigation lies in the high number of observed fillings, which had been performed under the same clinical conditions in daily clinical routine over a long period. All treatments were performed following a treatment protocol, without relevant changes in methods or materials over time. In this longitudinal retrospective study, some specific information was not included, for example, behaviour of the child during the treatment procedure, detailed caries extension, and treatment time needed for each restoration. Another, potential drawback might
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be the lack of standardized calibration training over the observation period as used in prospective studies. Although such variables are controlled in prospective randomized controlled trials, it is mostly impossible to exclude such potential bias in retrospective studies. Potential bias might be also result from the non-blinded evaluation by the operators and the remuneration system. While the first aspect can0 t be excluded, it should pointed out that the clinic is earning a fixed dental fee per patient and quarter. Safeguarding optimal dental preventive and operative dental care on the one side, there is, on the other hand, no economic stimulus available to provide any kind of overtreatment. In this study, we used strict control intervals as several patients did not kept their appointments in the dental clinic as recommended and, therefore, had long intervals between follow-up visits. In those cases, the calculation of the survival time using the date halfway between the last dental visit at which the restoration was considered acceptable, and the date of insufficiency would overrate the survival widely. Therefore, we decided to use this conservative approach. The corollary is a short mean observation time of
Risk factors for secondary caries in direct composite restorations in primary teeth ISABEL METZ1, KATRIN ROTHMAIER1, VINAY PITCHIKA1, ALEXANDER CRISPIN2, 1 1 € € REINHARD HICKEL1, FRANKLIN GARCIA-GODOY3, KATHARINA BUCHER & JAN KUHNISCH 1
Department of Conservative Dentistry, Ludwig-Maximilians University Munich, Munich, Germany, 2Institute for Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians University Munich, Munich, Germany, and 3Department of Bioscience Research, University of Tennessee Health Science Center, Memphis, TN, USA
International Journal of Paediatric Dentistry 2015 Background. Secondary caries or caries adjacent
to restorations is the most frequent reason for replacement of dental restorations. Though, limited data is available on variables influencing the development of secondary caries in primary teeth. Aim. To investigate risk factors for the development of secondary caries adjacent to direct composite restorations in primary teeth. Design. For this retrospective study, data of 2417 composite restorations, which were placed due to primary carious lesions, were considered. A total of 212 restorations failed due to secondary caries within a maximum observation period of 8 years. A control group was randomly selected. Mann–Whitney U-test, binomial logistic regression with backward
Introduction
Caries adjacent to restorations or secondary caries is defined as a carious lesion occurring at the cavity margins of dental restorations1 and is one of the most frequent reasons for filling replacement in primary2 and permanent2–4 teeth. Some controversy exists about the choice of restorative materials having an influence on the progression or inhibition of caries. Some studies have shown that, in the permanent dentition composite fillings are more frequently associated with the development of secondary caries than restorations performed with amalgam2,4,5, compomer, and glass ionomer cement6. In contrast, some studies did Correspondence to: Jan K€ uhnisch, Ludwig-Maximilians Universit€ at M€ unchen, Poliklinik f€ ur Zahnerhaltung und Parodontologie, Goethestraße 70, 80336 M€ unchen, Germany. E-mail: [email protected]
elimination and Cox regression with frailty model were performed (P < 0.05). Results. The overall caries experience amounted to 6.3 dmft and 13.3 dmfs. 72.5% of restorations failed within the first 2 years. Older children and children from families with a higher socio-economic status showed a lower risk for secondary caries. Further, the dentist and the adhesive had a significant influence on the longevity. Posterior restorations had a higher risk to fail in comparison with anterior restorations. Conclusions. Within the limitation of this study, it is concluded that the development of secondary caries is influenced by several factors. Nevertheless, the secondary caries rate was found to be relatively low in this high-risk population.
not find any significant influence of the material used or even showed an adverse effect7. For the primary dentition, similar outcomes can be found in the literature. Different working groups documented a higher8, lower9, or equal risk10 for secondary caries for composite and compomer materials. For the permanent dentition, the influential factors on the longevity of composite restorations have been investigated thoroughly. The most significant reason for the occurrence of secondary caries appeared to be the patientrelated caries risk5 also elevating the number of pre-existing restorations2–4. In addition, patients’ age3, tooth type4, cavity size2,4, preparation, and depth3 as well as the location of the restoration in the maxilla or mandible4 may have an influence on the development of secondary caries. Although these factors were significant for the permanent dentition, only few studies elucidated the reasons for secondary caries in the primary dentition. Until now, sparse data show
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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I. Metz et al.
that the number of filled surfaces in composite fillings had an influence on caries progression adjacent to restoration margins10. This further implies that investigations regarding the factors which are related to secondary caries in the primary dentition are needed. Therefore, the aim of this retrospective study was to identify potential risk factors for the development of secondary caries of composite fillings. The null hypothesis was that these variables will not have a significant influence on caries formation adjacent to restoration margins (null hypothesis). Materials and methods
This retrospective investigation was conducted in accordance with the Declaration of Helsinki and the ISPOR Task Force on Retrospective Databases11. Approval by the Ethics Committee of the Medical Faculty of the Ludwig-Maximilians University of Munich had been retrieved prior to the investigation (Project number: 030-13). Study population, inclusion, and exclusion criteria For this retrospective survey data of children aged 1–13 years (mean 6.6) who had been treated at the Department of Paediatric Dentistry between January 2004 and December 2012 were considered. Out of this patient group, all direct composite fillings on primary teeth that were placed due to primary caries and without sedation or general anaesthesia were included into the data set. Data were not admitted if the dental treatment was associated with other reasons than caries, for example, fillings due to trauma, hypomineralization, or hypoplasia of tooth structure. Also, composite restorations prior to stainless steel crowns were excluded. The data were recorded blinded according to a standardized procedure. With respect to these criteria, 2417 composite restorations were identified. For each case, relevant patient-related data (age, gender, health insurance status, and dmft index at the first appointment12) were recorded. Regarding health insurance status, it has to be noted that in Germany, a private health
insurance is linked to a higher socio-economic status of the insured parent represented by an above-average income and mostly university education. Furthermore, restoration- (Black’s classification, number of filled surfaces) and treatment-related factors (use of dental dam, adhesive and composite material, and operating dentist) were included. In addition, information from the recall appointments, for example, dichotomized assessment (sufficient, insufficient) of the filling quality according to the FDI criteria1,13, reasons of insufficiency (secondary caries, loss of retention, gap at the margin, fracture, total loss, tooth fracture, allergic reaction, and others), performed extraction, and the restoration survival time were collected. Treatment protocol Each patient was treated according to the same treatment protocol, which was individualized and adapted to every patients0 needs. Behaviour management techniques, for example, tell-show-do, systematic desensitization, and positive reinforcement were used appropriately to enhance the child’s cooperation. Following the protocol, after retrieving detailed medical history, dental cleaning was performed prior to a thorough clinical examination. Standardized visual caries examination14 was used for caries diagnostics, and bitewing radiographs were performed according to the prescription guidelines for dental radiographs, if indicated15,16. All diagnoses were registered in detail, and caries-related findings were used to calculate the dmft index12. Dentine caries was excavated and restored with a composite restoration. The operating procedure consisted of the following steps. Before beginning with the dental treatment, local anaesthesia was recommended if necessary to provide appropriate analgesia. To ensure an adequate isolation, either dental dam in split dam technique or cotton roll was used. In the first step of caries excavation, the access cavity was prepared minimally invasive using high-speed diamond-coated burs (Gebr. Brassler GmbH & Co. KG, Lemgo, Germany) with water
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Risk factors for secondary caries
cooling. Subsequently, deep caries lesions were excavated with low-speed tungsten carbide burs (Gebr. Brassler GmbH & Co. KG), hand excavators (Hu Friedy, Rotterdam, Netherlands) and/or the self-limiting burs SmartPrep (SS White, Lakewood, NJ, USA), SmartPrepII (SS White), or PolyBur P1 (Komet Dental Gebr. Brasseler GmbH & Co. KG). The excavation was considered completed when the remaining dentine was hard/solid. In case of an active and deep caries lesion, a calcium hydroxide liner (Kerr Life, Kerr Corporation, Orange, CA, USA) was applied. If the carious process involved the pulp, a vital pulpotomy was performed17. Cavity margins were cleaned conventionally until sound hard tissue remained to achieve optimal prerequisites for the marginal seal. For proximal cavities, a retainerless matrix system (AutoMatrix, Dentsply De Trey, York, PA, USA) and wedge were placed. Then the cavity was conditioned either using total etch with 37.5% phosphoric acid (Total Etch, Ivoclar Vivadent, Schaan, Liechtenstein) for ~10 seconds and total bond (Syntac Classic, Ivoclar Vivadent, Schaan, Liechtenstein) or a self-etching adhesive (Clearfil SE Bond, Kurarary Europe, Frankfurt, Germany). Following to this, the cavity was filled with a flowable composite (Tetric (Evo) Flow, Ivoclar Vivadent, Schaan, Liechtenstein) and/or a (nano-) hybrid composite material (Tetric (Evo) Ceram, Ivoclar Vivadent, Schaan, Liechtenstein). Every increment did not exceed more than 2 mm of thickness. The minimum cumulative polymerization time for each restoration amounted to 20 s. For polishing and finishing, appropriate rotating rubber polishers, for example, Enhance (Dentsply Caulk, Milford, DE, USA), were used. All patients were recommended to be included into an intensified preventive programme with intervals dependant on their caries risk, usually from 3 to 4 months. These appointments included dental cleaning and application of fluoride varnish as well as an individualized oral hygiene motivation and instruction as well as nutritional advice for patients and caretakers. In general, all fillings were assessed retrospectively according the FDI criteria for evaluation of direct restorations1,13. In case of any insufficiency, for example, caries with cavitation and undermining caries, deep caries, or
3
exposed dentine (that was not accessible for repair of restoration)1, fillings were repaired or replaced immediately or at the next appointment. The evaluators were the same clinicians, who placed the restorations, and, additionally, they had no knowledge about participating in a scientific study. All operating dentists followed a conservative and critical diagnostic model. A cavity at the margin of a restoration was considered to be secondary caries, but a discoloured margin was not. The clinical diagnosis of a secondary caries is a ‘soft criteria’ and may vary between dentists1,13. Eight fully graduated dentists performed all treatments. Operator 1, 2, and 5 are specialists for paediatric dentistry and had more than 5 years of clinical experience at the beginning of the observation time. In contrast, the operators 3, 4, 6, 7, and 8 had little clinical experience at the beginning and increased their skills over the time. The operators 1–8 also evaluated all of the restorations. Statistical analysis The study-related data were entered in a spreadsheet programme (Microsoft Office Excel 2007, Unterschleissheim, Germany) and analysed using SPSS software, version 21.0 (SPSS Inc., an IBM Company, Chicago, IL, USA) and R software (version 3.0.2, R Development Core Team, Vienna, Austria). To calculate the correct survival time for each composite restoration, the observation period was determined as the difference between the date on which the filling was placed and the latest appointment on which the filling was assessed as sufficient. If the filling was sufficient but the tooth was extracted or exfoliated, the survival of the restoration ended at the date of extraction or at the last date when the tooth was evaluated. Each restoration was observed until the respective date. Five hundred and seven of 2417 restorations had no follow-up and therefore a survival time of 0 days. The remaining 1910 restorations had a survival time of >1 day. Years were expressed by days, with 365 days counting as a full year, 730 days as 2 years
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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and so on. In cases of a new independent restoration on a tooth at a different surface, the monitored restoration was not considered as a failure. The maximum and mean observation time was calculated. For calculation, two groups were defined. According to the dental records, a total of 212 restorations failed due to secondary caries and were used as one group. For the control group, 212 intact fillings without failures were selected randomly from the remaining data set to have a 1:1 comparison. Mann–Whitney Utest was performed to calculate the significant differences between the secondary caries group and the control group. Hazard ratios for the failure of the composite restorations were calculated using binomial logistic regression with backward elimination model. The eliminated factors from this model were also presented in the results table to provide information on those variables. Additionally, Cox regression was performed using frailty model to adjust for
the clustering of the data due to the presence of multiple fillings in some patients. To avoid bias from random sampling of control population, we further repeated binomial logistic regression and Cox regression by entering all the controls into the models. The two-tailed significance level for all analyses was set at P < 0.05. Results
A total of 2417 composite restorations matched the inclusion criteria. Whereas in 8.8% (212/ 2417) of cases, fillings became insufficient due to secondary caries; another 8.2% (199/2417) were lost due to other reasons over the observation (Figs 1 and 2). The maximum observation period was 8 years, while the mean observation time was 1.9 years (SD 1, 1 years) for the 1:1 control sampling and 1.1 years (SD 1.3 years) for the 1:all control sampling. 72.6% (154/212) of the secondary caries lesions were
Fig. 1. Number of healthy composite restoration and those with secondary caries in relation to the time point of diagnosis. Overall restorations with secondary caries (n = 212).
Fig. 2. Reasons for composite restoration failure during the observation period. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Risk factors for secondary caries
diagnosed during the first 2 years after application of the composite restorations (Fig. 1). The paediatric patients in both groups had a similar caries experience (Table 1). In Table 2, patient- and restoration-related information is given. In logistic regression models, the patient’s age, health insurance status, and the location of the restorations according to Black0 s classification were tested to have a significant influence on the development of secondary caries. The risk for a composite restoration to become insufficient due to secondary caries decreased continuously with increasing age, beginning from age 3. A private health insurance status reduced further the risk for establishing a secondary caries. Most frequently, secondary caries was diagnosed in primary molars (Class I–II). In Table 3, treatment-related data are listed, and two variables were significant in logistic regression models. The use of phosphoric acid in combination with a total bond adhesive showed higher risk for failure compared to a self-etching adhesive. The analysis of the operating dentists showed heterogeneous results. Whereas some operators treated their patients with a reduced risk of getting secondary caries, for others, the opposite results were registered. Discussion
The present retrospective study was conducted to evaluate variables with potential influence on the development of secondary caries adjacent to composite restorations in
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primary teeth. Basic characteristics of the study population showed a high caries risk represented by a high mean caries experience of 6.3 caries affect teeth, which is approximately three times higher compared to the mean caries experience of this age group in Bavaria18 and is representing the typical situation of children with early childhood caries. A major influencing factor in this investigation was secondary caries, which exposed to be the most frequent reason for an insufficient filling in primary teeth. This finding was in line with several other studies2–4,19. In comparison to other clinical trials, the frequency of secondary caries development appeared to be rather low in this investigation, because failures of fillings due to secondary caries were lower than 10% over the maximum observation period of 8 years. A major reason for this finding could be the intensified preventive care during a clinical trial that was performed; this may have influenced the oral health positively and reduced the risk for secondary caries in this caries risk cohort. Re-evaluation and demonstration of proper oral hygiene techniques within the dental visits increase the probability of better oral health20; therefore, it has to be safeguarded by the parents. By practicing and rebrushing their children’s teeth, parents are able to ensure a good quality of oral hygiene and extend the longevity of their children’s restorations. Also, it is in the families’ responsibility to control drinking and eating habits to ensure a tooth-friendly nutrition. Therefore, our intensified preventive intervention
Table 1. Caries experience of the patients at the first appointment.
Caries experience at the 1st appointment
Patients with restorations with secondary caries (SD)
Patients with control restorations (SD)
Overall patients Mean (SD)
dmft dt mt ft dmfs ds ms fs
6.5 4.8 0.3 1.5 13.9 8.5 1.3 4.1
6.1 4.6 0.4 1.2 12.7 8.1 1.4 3.2
6.3 4.7 0.3 1.3 13.3 8.3 1.4 3.7
(3.6) (3.5) (0.9) (2.2) (12.3) (9.5) (3.9) (7.0)
SD, standard deviation. Bold: P < 0.05, Mann–Whitney U-test. © 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
(3.8) (3.5) (1.2) (2.2) (11.0) (8.6) (4.5) (6.1)
(3.7) (3.5) (1.0) (2.2) (11.7) (9.1) (4.2) (6.6)
15.1 33.0 33.0 15.1 3.8 42.5 57.5 99.5 – 0.5 25.0 58.5 9.4 1.4 5.7 33.0 55.7 8.0 3.3
90 122 211 – 1 53 124 20 3 12 70 118 17 7
%
32 70 70 32 8
n
HR, hazard ratio. Bold: P < 0.05 using Cox regression model.
Patient’s age (in years) 0–3 4–5 6–7 8–9 10–14 Patient’s gender Female Male Patient’s health insurance status National health ins. Self-financing Private health ins. Black’s classification Class I Class II Class III Class IV Class V Number of restored tooth surfaces 1 2 3 >4
Patient- and restoration-related variable
Restorations with secondary caries
64 124 15 9
34 130 19 13 16
192 – 20
95 117
15 52 57 57 31
n
30.2 58.5 7.1 4.2
16.0 61.3 9.0 6.1 7.5
90.6 – 9.4
44.8 55.2
7.1 24.5 26.9 26.9 14.6
%
Control restorations
1.0 0.9 1.8 3.2
1.0 1.2 0.8 0.1 0.4
1.0 – 0.2
1.0 1.2
1.0 0.5 0.4 0.2 0.0
OR
1.0 0.9 0.9 0.9 0.7 1.0 1.1 1.0 – 0.1 1.0 1.2 1.4 0.5 0.8 1.0 0.8 1.0 1.4
– 0.8–1.9 – – 0.1–0.6 – 0.7–2.1 0.3–1.8 0.0–0.6 0.2–1.0 – 0.5–1.7 0.6–5.2 0.5–19.3
HR
– 0.5–1.3 0.5–2.1 0.5–4.1
– 0.7–2.1 0.7–2.9 0.1–2.1 0.4–1.6
– – 0.0–0.8
– 0.7–1.6
– 0.4–2.4 0.5–1.5 0.5–1.7 0.4–1.3
95% CI
Cox regression model/Frailty model
– 0.2–1.0 0.2–1.0 0.1–0.4 0.1–0.6
95% CI
Logistic regression analysis
1:1 control sampling
Table 2. Descriptive data and results from the regression models of patient- and restoration-related variables.
645 1111 142 57
346 1151 206 71 181
1734 82 139
909 1046
136 459 625 521 214
n
33.0 56.8 7.3 2.9
17.7 58.9 10.5 3.6 9.3
88.7 4.2 7.1
46.5 53.5
7.0 23.5 32.0 26.6 10.9
%
Control restorations
1.0 1.1 1.2 1.9
1.0 1.2 1.1 0.7 0.5
1.0 0.4 0.1
1.0 1.2
1.0 0.7 0.5 0.5 0.5
OR
– 0.7–1.8 0.6–2.2 0.7–4.9
– 0.9–1.7 0.7–1.9 0.2–2.1 0.2–0.9
– 0.1–1.2 0.0–0.6
– 0.9–1.5
– 0.4–1.0 0.3–0.8 0.3–0.8 0.2–1.0
95% CI
Logistic regression analysis
1: all control sampling
1.0 1.1 1.2 2.6
1.0 1.0 0.9 0.4 0.4
1.0 0.5 0.1
1.0 1.2
1.0 0.8 0.7 0.6 0.6
HR
– 0.7–1.8 0.6–2.5 0.9–7.7
– 0.6–1.6 0.5–1.8 0.1–1.5 0.2–0.8
– 0.1–1.9 0.0–0.6
– 0.8–1.9
– 0.5–1.5 0.4–1.2 0.3–12 0.2–1.5
95% CI
Cox regression model/Frailty model
6 I. Metz et al.
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
DOI: 10.1111/ipd.12157
Risk factors for secondary caries in direct composite restorations in primary teeth ISABEL METZ1, KATRIN ROTHMAIER1, VINAY PITCHIKA1, ALEXANDER CRISPIN2, 1 1 € € REINHARD HICKEL1, FRANKLIN GARCIA-GODOY3, KATHARINA BUCHER & JAN KUHNISCH 1
Department of Conservative Dentistry, Ludwig-Maximilians University Munich, Munich, Germany, 2Institute for Medical Informatics, Biometry and Epidemiology, Ludwig-Maximilians University Munich, Munich, Germany, and 3Department of Bioscience Research, University of Tennessee Health Science Center, Memphis, TN, USA
International Journal of Paediatric Dentistry 2015 Background. Secondary caries or caries adjacent
to restorations is the most frequent reason for replacement of dental restorations. Though, limited data is available on variables influencing the development of secondary caries in primary teeth. Aim. To investigate risk factors for the development of secondary caries adjacent to direct composite restorations in primary teeth. Design. For this retrospective study, data of 2417 composite restorations, which were placed due to primary carious lesions, were considered. A total of 212 restorations failed due to secondary caries within a maximum observation period of 8 years. A control group was randomly selected. Mann–Whitney U-test, binomial logistic regression with backward
Introduction
Caries adjacent to restorations or secondary caries is defined as a carious lesion occurring at the cavity margins of dental restorations1 and is one of the most frequent reasons for filling replacement in primary2 and permanent2–4 teeth. Some controversy exists about the choice of restorative materials having an influence on the progression or inhibition of caries. Some studies have shown that, in the permanent dentition composite fillings are more frequently associated with the development of secondary caries than restorations performed with amalgam2,4,5, compomer, and glass ionomer cement6. In contrast, some studies did Correspondence to: Jan K€ uhnisch, Ludwig-Maximilians Universit€ at M€ unchen, Poliklinik f€ ur Zahnerhaltung und Parodontologie, Goethestraße 70, 80336 M€ unchen, Germany. E-mail: [email protected]
elimination and Cox regression with frailty model were performed (P < 0.05). Results. The overall caries experience amounted to 6.3 dmft and 13.3 dmfs. 72.5% of restorations failed within the first 2 years. Older children and children from families with a higher socio-economic status showed a lower risk for secondary caries. Further, the dentist and the adhesive had a significant influence on the longevity. Posterior restorations had a higher risk to fail in comparison with anterior restorations. Conclusions. Within the limitation of this study, it is concluded that the development of secondary caries is influenced by several factors. Nevertheless, the secondary caries rate was found to be relatively low in this high-risk population.
not find any significant influence of the material used or even showed an adverse effect7. For the primary dentition, similar outcomes can be found in the literature. Different working groups documented a higher8, lower9, or equal risk10 for secondary caries for composite and compomer materials. For the permanent dentition, the influential factors on the longevity of composite restorations have been investigated thoroughly. The most significant reason for the occurrence of secondary caries appeared to be the patientrelated caries risk5 also elevating the number of pre-existing restorations2–4. In addition, patients’ age3, tooth type4, cavity size2,4, preparation, and depth3 as well as the location of the restoration in the maxilla or mandible4 may have an influence on the development of secondary caries. Although these factors were significant for the permanent dentition, only few studies elucidated the reasons for secondary caries in the primary dentition. Until now, sparse data show
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
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includes oral hygiene instructions, motivations, and nutritional advice for the patients as well as for their parents. The analyses showed further that, especially the first 2 years after placing the filling turned out to be the most critical time for secondary caries development in primary teeth. This finding is inverse to a recently published meta-analyses from Opdam et al.21; the authors showed an increasing onset of secondary caries especially in the later years of observation in permanent teeth. These contrary findings can be explained by the high caries risk of children affected by early childhood caries22. In children whose families do not change their nutritional behaviour and oral hygiene procedures, a rapid initiation of new caries lesions, the progression of existing non-cavitated caries lesions, and/or the onset of secondary caries within a short period of time after restoration placement can be observed. The documented early onset of secondary caries in this study indicates that some patients obviously do not benefit from the intensified preventive care and, therefore, will be affected by a caries reversal shortly after primary rehabilitation. Contrary to this situation, adult persons may follow preventive advice with higher probability and, mostly, secondary caries will be diagnosed in later years. Another important aspect for the registered early onset of secondary caries in our study might be the challenging situation to treat young children without using the option of general anaesthesia. A limited ability of the child for cooperation and the requirement to perform dental procedure in a minimum of time while endeavouring to safeguard sensitive treatment protocols can reduce the quality of a restoration. Therefore, the early onset of secondary caries might indicate that the restorations had insufficiencies already present immediately after placement. This might be possible as all restorations of this study were performed in an outpatient dental setting and no sedation technique or general anaesthesia was used. This investigation aimed to identify potential risk factors for the development of secondary caries of composite fillings in primary teeth. An influential patient-related variable
seems to be the paediatric patient’s age. Older children (age > 3 years) have obviously a lower risk for secondary caries than younger patients. This is naturally linked to the difficulties treating young children due to a limited ability of the younger child to cooperate. Also, eventually, treatment of the more uncooperative child will lead to compromises in treatment and might further affect the restoration quality. If such errors occur, a rapid caries development could be observed, which result in a shorter survival time. This concerns all filling materials, but especially those which are sensitive to time, moisture, and a setting time over some few minutes. The analysis of the health insurance status illustrated that the hazard for secondary caries was significantly reduced when the patient’s parents had a private health status. This insurance status is linked to a higher socioeconomic status, above-average income, and, mostly, university education of the parents and has to be kept in mind while interpreting these results. The association of those factors and caries development in children was also confirmed in other studies23. A filling-related and significant variable was the type of cavity. Composites on the occlusal (Class I) and proximal surfaces (Class II) of primary molars showed a higher risk compared to all other types of cavitations. In detail, similar to the result from a previous study10,24, Class II restorations had a (slightly) higher risk compared to Class I restorations. In addition, a greater filling size (number of restored tooth surfaces) tended to have a higher risk for secondary caries. This variable was not as significant, but several authors had reported lower survival rates for multisurfaced restorations in primary teeth10,24 before. The overall high number of cases for Class I and II indicates that posterior teeth are more susceptible for (secondary) caries in primary dentition compared to anterior teeth. A possible reason could be the specific anatomy of primary molars with deep fissures and extensive proximal surfaces. An excellent plaque removal is challenging for these teeth, and it has been shown that significantly more dental plaque was found on molars in
© 2015 BSPD, IAPD and John Wiley & Sons A/S. Published by John Wiley & Sons Ltd
Risk factors for secondary caries
contrast to anterior teeth prior and immediately after tooth brushing25. Analysing the treatment-related variables, the operating dentist turned out to have a significant impact like Opdam et al.26 found for permanent dentition. In this study, all operators used similar materials and treatment protocols. Nevertheless, the outcome was heterogeneous. An explanation could be that the professional experiences and skills of the dentist varied and might have influenced the quality and longevity of the restoration. The use of a self-etching adhesive reduced the risk for failure in comparison with phosphoric acid in combination with a total bond adhesive. This is in line with Koshiro et al.27, who showed a higher resistant to degradation of the adhesive interface produced by the self-etch system compared to the adhesive interface produced by the etch-and-rinse adhesive. In addition, a reduced application time, which is relevant especially in paediatric patients, might affect the restorations quality and longevity. Dental dam had no significant influence in both regression analyses. But this result might be owed by the low number of cases and, therefore, the reduced statistical strength of this variable. Nevertheless, dental dam may have the potential to affect the quality of a restoration in a positive way and lead to a protective effect regarding the risk of secondary caries. Based on the results, the null hypothesis was rejected as several variables turned out to have significant effects. This study was a retrospective analysis of patient’s records. So far, only a limited number of studies analysing composite restorations in primary teeth is available10,19,24,28,29. The strength of this investigation lies in the high number of observed fillings, which had been performed under the same clinical conditions in daily clinical routine over a long period. All treatments were performed following a treatment protocol, without relevant changes in methods or materials over time. In this longitudinal retrospective study, some specific information was not included, for example, behaviour of the child during the treatment procedure, detailed caries extension, and treatment time needed for each restoration. Another, potential drawback might
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be the lack of standardized calibration training over the observation period as used in prospective studies. Although such variables are controlled in prospective randomized controlled trials, it is mostly impossible to exclude such potential bias in retrospective studies. Potential bias might be also result from the non-blinded evaluation by the operators and the remuneration system. While the first aspect can0 t be excluded, it should pointed out that the clinic is earning a fixed dental fee per patient and quarter. Safeguarding optimal dental preventive and operative dental care on the one side, there is, on the other hand, no economic stimulus available to provide any kind of overtreatment. In this study, we used strict control intervals as several patients did not kept their appointments in the dental clinic as recommended and, therefore, had long intervals between follow-up visits. In those cases, the calculation of the survival time using the date halfway between the last dental visit at which the restoration was considered acceptable, and the date of insufficiency would overrate the survival widely. Therefore, we decided to use this conservative approach. The corollary is a short mean observation time of
