CLINICAL STUDY

Does the Time of Osseointegration in the Maxilla and Mandible Differ? Sergio Alexandre Gehrke, DDS, PhD,*† and Ulisses Tavares da Silva Neto, DDS, PhD‡ Objectives: The objectives of the present study were to measure the implant stability quotient (ISQ) values at 3 different time points after the surgical insertion and to determine whether the time of osseointegration differs in the maxilla and mandible. Materials and Methods: To measure implant stability, resonance frequency analysis (RFA) was performed in 44 patients (40 women, 4 men) with a total of 100 Implacil De Bortoli implants; the patients were divided into 2 groups: group 1, implants in the maxilla (22 in the anterior maxilla and 37 in the posterior maxilla); and group 2, implants in the mandible (41 posterior mandibles). Using RFA, implant stability was measured immediately after implant placement to assess the immediate stability (time 1) and at 90 (time 2) and 150 (time 3) days. Results: Overall, the mean (SD) ISQ was 63.3 (6.63) (95% confidence interval [CI], 39–79) for time 1, 70.5 (6.32) (95% CI, 46– 88) for time 2, and 73.5 (6.03) (95% CI, 58–88) for time 3. In group 1, the mean (SD) ISQ was 61.8 (6.56) (95% CI, 39–79) for time 1, 68.8 (5.19) (95% CI, 57–83) for time 2, and 72.3 (5.91) (95% CI, 58–85) for time 3. In group 2, the mean (SD) ISQ was 65.5 (6.13) (95% CI, 44–75) for time 1, 72.9 (7.02) (95% CI, 46–88) for time 2, and 75.3 (5.80) (95% CI, 60–88) for time 3. Conclusions: The stability of the implants placed in the maxilla and mandible showed a similar evolution in the ISQ values and, consequently, on osseointegration; however, the implants in the mandible presented superior values at all time points. Key Words: Resonance frequency analysis, dental implant, osseointegration in maxilla, osseointegration in mandible (J Craniofac Surg 2014;25: 2117–2120)

D

ental implants require sufficient alveolar bone, both in width and in length, to acquire adequate primary stability and to eventually exert its support function. In some cases, such as severely atrophic edentulous mandibles and very pneumatized maxillary sinus, which lack bone augmentation, implant treatment is not an option for patients with severe alveolar bone absorption. In addition, bone loss also results in some problems in the anterior maxilla From the *Biotecnos Research Center, Santa Maria, Brazil, and †Catholic University of Uruguay, Montevideo, Uruguay; and ‡Postgraduate Program in Implantology of Associação Paulista de Cirurgiões Dentistas, Jundiaí and Osasco, Brazil. Received February 7, 2014. Accepted for publication April 24, 2014. Address correspondence and reprint requests to Sergio Alexandre Gehrke, DDS, PhD, Biotecnos Research Center, Rua Dr Bozano 571, CP 97015-001, Santa Maria, RS, Brazil; E-mail: [email protected] The authors report no conflicts of interest. Copyright © 2014 by Mutaz B. Habal, MD ISSN: 1049-2275 DOI: 10.1097/SCS.0000000000001067

for aesthetic reasons.1 However, patients with implant placement should expect 3 to 6 months for successful osseointegration and final permanent restoration. Therefore, augmenting alveolar bone and shortening the wait time are two major clinical challenges for dental implantology.2 Implant stability is a prerequisite for the long-term clinical success of implants and depends on the quantity and quality of local bone, the implant design, and the surgical technique used (subinstrumentation or overinstrumentation).3 The changes that occur during tissue healing, such as bone resorption and integration of the bone-implant interface, can determine the degree of secondary stability of the implant. Obviously, the healing process will be affected by bone morphology, including the trabecular pattern and the density and degree of maturation.4 There are different methods of measuring implant stability, such as the PeriotestR (Gulden, Bensheim, Germany) or the Dental Fine TesterR (Kyocera, Kyoto, Japan); however, these methods have been criticized for their lack of resolution, poor sensitivity, and susceptibility to being operator influenced.5 Resonance frequency analysis (RFA) offers a clinical, noninvasive measure of stability and presumed osseointegration of implants6,7 and is a useful tool to establish implant loading time.8 The RFA values are represented by a quantitative unit called the implant stability quotient (ISQ) on a scale from 1 to 100 and are measured with the Osstell R (Integration Diagnostics AB, Gothenburg, Sweden); an increased ISQ value indicates increased stability.6 Clinically, RFA values have been correlated with changes in implant stability during osseous healing, failure of implants to integrate, and the supracrestal dimensions of the implant.3,5 The objectives of the present study were to measure the ISQ values at 3 different time points after the surgical insertion (immediately and after 12 and 20 weeks) to evaluate the influence of the implant diameter and design and to determine whether there is a difference between the time of osseointegration in the maxilla and mandible.

MATERIALS AND METHODS A total of 44 patients were included in this study; there were 40 women and 4 men, and the patients’ ages ranged between 39 and 68 years. The study was approved by the ethics and research committee of São Leopoldo Mandic University (Campinas, Brazil). All patients were informed regarding the nature of the study and their participation, and written consent was granted by every patient according to the Helsinki Declaration of 1994. The inclusion criteria were based on the patients’ current stable medical condition, their ability to withstand the stress of a dental implant surgery, and the request for implants in the maxilla or mandible; all included patients agreed to participate in the implant stability study based on RFA for a period of 20 weeks. In addition, cases that the immediate load was not indicated were included. Patients were not included if they had unstable systemic conditions such as diabetes, hypertension, or osteoporosis; oral pathology in their soft or hard tissues; or harmful oral habits such as bruxism

The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

2117

Gehrke and da Silva Neto

The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014

and smoking. Exclusion criteria based on the local implant site included the presence of uncontrolled or untreated periodontal disease, insufficient bone volume for implant insertion without augmentation procedures, and active infection in the area or an apical cyst. Patients were classified based on the local condition of the implant insertion site: condition 1 (C1), implants in normal areas (conventional technique); condition 2 (C2), immediate implants after extraction in alveolus; condition 3 (C3), implants installed with bone expansion; and condition 4 (C4), implants placed in previously grafted areas (inlay or onlay). The following clinical information was collected: patient age and sex, implant location, implant model, implant length and diameter, and condition of the implantation site.

Surgical Procedure Standard routine surgical procedures were applied. Patients were premedicated with amoxicillin (875 mg orally, twice per day) for 5 days, and an initial dose (2 g) was administered 2 hours before surgery. All surgical procedures were performed under local anesthesia with 2% of Articaína (Dfl Ltda, Rio de Janeiro, Brazil) in an outpatient setting by the same surgeon who was familiar with the implant brand. For the procedure, a full-thickness mucoperiosteal flap was elevated, and when necessary, tooth extraction was placed, and the osteotomy was realized. The osteotomies were produced using the conventional drilling method (according to the manufacturer’s instructions). A total of 100 conical implants were inserted: 59 in the maxilla (group 1) and 41 in the mandible (group 2); the implants had a sandblasted titanium oxide and acid-treated surface, internal hexagon (IH) (n = 58), and Morse taper (MT) (n = 42) connection (Implacil De Bortoli, São Paulo, Brazil), with 2 diameters of 3.5 (n = 30) and 4 (n = 70) mm and lengths ranging from 8 to 13 mm. The implants were selected based on the previous evaluation of each patient as required. The reference to the connection type was due to differences in the characteristics of the cervical area of these 2 models, as shown in Figure 1. For drilling, a Kavo Concept motor (KaVo Dental GmbH, Biberach, Germany) and a counter-angle Kavo with a 27:1 reduction was used as well as external irrigation with 0.9% of saline solution. All implants were installed with the use of surgical guides, and the wounds were sutured. Cetoprofeno (200 mg/d) and Paracetamol (750 mg, 3 times per day) were administered for pain relief for 3 days after surgery. All implants were submerged for 12 weeks with a healing abutment until the initiation of rehabilitation after 20 weeks. Between 12 and 20 weeks, restorative procedures were performed (impressions as well as metal and ceramic proofs). After implant insertion, the resonance frequency evaluation was performed using the Ostell Mentor (Integration Diagnostics AB, Göteborg, Sweden) for the magnetic RFA measurements. A Smartpeg (Integration Diagnostics AB, Göteborg, Sweden) was screwed into each implant and tightened to approximately 5 Ncm. The transducer probe was aimed at the small magnet at the top of the Smartpeg at a distance of 2 or 3 mm and held stable during the pulsing until the instrument beeped and displayed the ISQ value. The ISQ values were measured during the surgical procedure (time 1),

FIGURE 2. The measurement of ISQ.

at 12 weeks (time 2) after surgery, and at 20 weeks (time 3) after surgery (Fig. 2). The measurements were taken twice in the buccolingual direction and twice in the mesiodistal direction.9 The mean of the 2 measurements in each direction was regarded as the representative ISQ for that direction. The higher buccolingual and mesiodistal ISQ values were used to generate a mean value, and all values were recorded. In addition, each implant was evaluated at all visits for mobility, pain, and signs of infection.

Statistical Analysis The outcomes were longitudinally analyzed within the same group using the 1-way analysis of variance test for repeated measures. The comparison between the 2 groups was performed using the z-test for unpaired samples (R Software version 2.6.2; R Foundation for Statistical Computing, Wien, Austria). The level of significance was set at α = 0.05.

RESULTS Of the 59 maxilla implants, 22 were installed in the anterior region between the canines, and 37 were installed in the posterior area; all of the mandible implants evaluated in this study were installed in the posterior area. All implants survived and were well osseointegrated. No patients dropped out of the study during the observation period. Twenty weeks after insertion, 100 of the implants were found to be osseointegrated. Overall, the mean (SD) ISQ was 63.3 (6.63) (95% confidence interval [CI], 39–79) for time 1, 70.5 (6.32) (95% CI, 46–88) for time 2, and 73.5 (6.03) (95% CI, 58– 88) for time 3. The distribution of the conditions of the implant site and the corresponding ISQ means per time point are shown in Table 1; conditions C1 and C2 presented higher values than conditions C3 and C4. Using a 1-way analysis of variance test comparing the 3 time points in each group, group 1 showed an F crit (3.047906) that was smaller than F calc (48.12823); in group 2, F crit (3.071779) was smaller than F calc (26.64838). The test result was highly significant, and it was thus concluded that there is an important effect among the groups, with significance set at P < 0.05. In group 1, the mean (SD) ISQ was 61.8 (6.56) (95% CI, 39– 79) for time 1, 68.8 (5.19) (95% CI, 57–83) for time 2, and 72.3 (5.91) (95% CI, 58–85) for time 3, as shown in the graph (Fig. 3). TABLE 1. The Distribution of the Conditions of the Implant Site and the Corresponding ISQ Means per Time Point

FIGURE 1. Design of the implants used in the study.

2118

Condition

n

C1

54 22 14 10

C2 C3 C4

ISQ Time 1 and SD ISQ Time 2 and SD ISQ Time 3 and SD 64.7 ± 5.78 63.4 ± 7.06 59.1 ± 7.75 61.6 ± 6.48

72.4 68.8 67.8 67.6

± 5.67 ± 7.32 ± 4.87 ± 6.36

74.9 ± 72.9 ± 71.6 ± 70.3 ±

5.82 5.74 6.39 6.02

© 2014 Mutaz B. Habal, MD

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014

In group 2, the mean (SD) ISQ was 65.5 (6.13) (95% CI, 44–75) for time 1, 72.9 (7.02) (95% CI, 46–88) for time 2, and 75.3 (5.80) (95% CI, 60–88) for time 3, as shown in the graph (Fig. 4). The z statistic was calculated to evaluate the differences among the groups at each time point. The null hypothesis for large samples (n > 30) was tested for α = 0.05. In all cases, the null hypothesis was rejected, that is, the z statistic was larger than the critical value (1.64). Comparing the evolution of the groups, both groups showed a similar pattern of an increase in the stability values (Fig. 5). A comparison of the implants in the maxilla based on the region where they were installed, anterior or posterior, showed a mean ISQ value that was higher at time 1 for the posterior maxilla; at the other time points, a very small difference (not significant) in the stability values for the 2 areas was observed (Fig. 6). A total of sixty-nine 4-mm diameter implants and thirty-one 3.5-mm diameter implants were installed; there were 58 IH implants and 42 MT implants. A statistically significant relationship was found between the RFA findings and the diameter (3.5 < 4 mm) and implant design (IH > MT), with significance set at P < 0.05.

Osseointegration in Maxilla and Mandible

FIGURE 4. Graph of the ISQ values and SD obtained in the mandible at the 3 time points.

Initial implant stability is a basic and fundamental requisite for accomplishing the osseointegration of implants. The quantity and location of cortical and trabecular bone surrounding the implants are important factors in the stability as they contribute to bone-implant contact.7 Clinical methods that are commonly used to assess implant stability and osseointegration include percussion, mobility tests, and clinical radiographs. All of these methods are limited by their lack of standardization, poor sensitivity, and susceptibility to operator variables.10,11 Recently, a modern and noninvasive diagnostic technique called RFA was used for the evaluation and measurement of the stability of implants within bone at different clinical stages.12 The reasons for the use of this technique were because it is rapid, straightforward, and easy to accomplish as part of a routine clinical procedure and there is no risk of patient discomfort. Most implants in the maxilla had an ISQ of 60.13 Other studies demonstrated that, after surgery, the mean (SD) ISQ values were higher in the mandible (59.8 [6.7]) than in the maxilla (55.0 [6.8]) using cylindrical implants.1,7 In this study, a value of 63.6 was obtained as a general average, 61.8 for group 1 and 65.5 for group 2; in all cases, the values were higher in the present study (conical implants) compared with those presented in the cited study (cylindrical implants), which may be related to the different types of implant used. However, it was observed that the mean value increased significantly after 12 and 20 weeks. Some authors found that there was a significant relationship between sex and Osstell value; a higher stability quotient was found in women than in men,14 whereas other authors reported that men showed higher implant stability than women.15 However, in a

long-term study, the authors established that the differences found between RFA, with respect to sex, were not clinically relevant as there were no differences in the failure rates between men and women.16 The present study included a small number of men, so this variable was not used in evaluating the present results. Bone density is a factor that influences the initial implant stability during insertion.1,17 The reported mean bone density of the implant site in some studies was 856.8 Hounsfield units for the mandible and 594.2 Hounsfield units for the maxilla.18 However, some authors reported that the mean bone mineral density of the mandible is 1.11 g/cm2, which is much larger than in the anterior maxilla (mean, 0.55 g/cm2) or the posterior maxilla (mean, 0.31 g/cm2).19 This result is consistent with the results of the present study, where the mandible presented the highest ISQ values at all time points compared with the maxilla, with a statistically significant difference. Despite this difference, when we examine the graph (Fig. 5) of the evolution of the ISQ values at the different time points, the behavior of the 2 groups (maxilla and mandible) is very similar, which suggests that the difference in stability values is due to the difference in bone density and not to any difference in the process and/or time of osseointegration. Some published studies comparing bone healing in the maxilla and mandible found no difference in time, quality, and quantity of regenerated bone tissue20; this occurs most likely because both bones have very similar characteristics that make the same embryonic origin, and therefore, the events in the repair process are identical. Then, these are the possible reasons for the similar evolution in the maxilla and mandible in the osseointegration process of the implants. The bone quality and implant stability is lower in the posterior area; for this reason, the posterior implant success rate is lower than that of the anterior. In the anterior area, the thick cortical bone and dense trabecular bone will increase primary stability.21 According to Seong et al22 (2009), there is no consensus in the literature about how the physical properties of bone vary between the maxillary and mandibular regions and which physical properties affect initial implant stability. A clinical study suggested that the use of thinner drills for implant placement in the maxillary posterior region where bone quality is poor may improve the primary implant stability, which helps physicians to obtain higher implant survival rates.23 However, in our study, based on the maxilla (anterior and

FIGURE 3. Graph of the ISQ values and SD obtained in the maxilla at the 3 time points.

FIGURE 5. Line graph comparing the evolution of the groups; both have a similar pattern of an increase in the ISQ values.

DISCUSSION

© 2014 Mutaz B. Habal, MD

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

2119

Gehrke and da Silva Neto

The Journal of Craniofacial Surgery • Volume 25, Number 6, November 2014

FIGURE 6. Line graph demonstrating the similar evolution and values between the anterior maxilla (AM) and posterior maxilla (PM).

posterior) data, there was a difference at baseline (time 1) with greater stability in the posterior maxilla, whereas at the other times, there was almost no difference. This variation in results may be related to that most of the anterior implants were installed in condition C3 (implants installed with bone expansion), which was the situation in which there were lower ISQ values. Some authors suggest that using longer and wider implants increases primary stability due to the increased bone-implant contact surface area.18,24,25 In the present study, only the diameter (3.5 and 4.0 mm) and the implant design, and not the length of the implant, were used as evaluation factors, and the results showed larger ISQ values with greater implant diameter, with statistical significance (P < 0.05). These results were not consistent with those found in other studies that reported no statistically significant differences with regard to length or diameter in relation to the ISQ.16,26 Regarding the design of the implant, IH implants with cervical microthreads showed higher stability in the 3 periods, with statistically significant values (P < 0.05). This result is consistent with the mean ISQ value of 62.1, which corresponds to all of the measurements on the day of surgery, in another study using cylindrical implants but with cervical microthreads.

CONCLUSIONS The stability of implants placed in the maxilla and mandible showed a similar evolution in the ISQ values; however, the implants in the mandible presented superior values at all times. Within the limitations of this study, comparing the data obtained, the osseointegration in the mandible and maxilla evolves similarly during the same period.

REFERENCES 1. Bischof M, Nedir R, Szmukler-Moncler S, et al. Implant stability measurement of delayed and immediately loaded implants during healing. Clin Oral Implants Res 2004;15:529–539 2. Buser D, Martin W, Belser UC. Optimizing esthetics for implant restorations in the anterior maxilla: anatomic and surgical considerations. Int J Oral Maxillofac Implants 2004;19:43–61 3. Friberg B, Sennerby L, Linden B, et al. Stability measurements of one-stage Branemark implants during healing in mandibles. A clinical resonance frequency analysis study. Int J Oral Maxillofac Surg 1999;28:266–272 4. Zix J, Hug S, Kessler-Liechti G, et al. Measurement of dental implant stability by resonance frequency analysis and damping capacity assessment: comparison of both techniques in a clinical trial. Int J Oral Maxillofac Implants 2008;23:525–530 5. Meredith N. Assessment of implant stability as a prognostic determinant. Int J Prosthodont 1998;11:491–501 6. Meredith N, Book K, Friberg B, et al. Resonance frequency measurements of implant stability in vivo. A cross-sectional and longitudinal study of resonance frequency measurements on implants in the edentulous and partially dentate maxilla. Clin Oral Implants Res 1997;8:226–233

2120

7. Barewal RM, Oates TW, Meredith N, et al. Resonance frequency measurement of implant stability in vivo on implants with a sandblasted and acid-etched surface. Int J Oral Maxillofac Implants 2003;18:641–651 8. Uribe R, Penarrocha M, Balaguer J, et al. Immediate loading in oral implants. Present situation. Med Oral Patol Oral Cir Bucal 2005; 1(Suppl 2):E143–E153 9. Sim CP, Lang NP. Factors influencing resonance frequency analysis assessed by Osstell mentor during implant tissue integration: I. Instrument positioning, bone structure, implant length. Clin Oral Implants Res 2010;21:598–604 10. Fischer K, Bäckström M, Sennerby L. Immediate and early loading of oxidized tapered implants in the partially edentulous maxilla: a 1-year prospective clinical, radiographic, and resonance frequency analysis study. Clin Implant Dent Relat Res 2009;11:69–80 11. Meredith N, Shagaldi F, Alleyne D, et al. The application of resonance frequency measurements to study the stability of titanium implants during healing in the rabbit tibia. Clin Oral Implants Res 1997;8:234–243 12. da Silva Neto UT, Joly JC, Gehrke SA. Clinical analysis of the stability of dental implants after preparation of the site by conventional drilling or piezosurgery. Br J Oral Maxillofac Surg 2013;19 13. Nedir R, Bischof M, Szmukler-Moncler S, et al. Predicting osseointegration by means of implant primary stability. Clin Oral Implants Res 2004;15:520–528 14. Brochu JF, Anderson JD, Zarb GA. The influence of early loading on bony crest height and stability: a pilot study. Int J Prosthodont 2005;18:506–512 15. Zix J, Kessler-Liechti G, Mericske-Stern R. Stability measurements of 1-stage implants in the maxilla by means of resonance frequency analysis: a pilot study. Int J Oral Maxillofac Implants 2005;20:747–752 16. Ostman PO, Hellman M, Wendelhag I, et al. Resonance frequency analysis measurements of implants at placement surgery. Int J Prosthodont 2006;19:77–83 17. Turkyilmaz I, Sennerby L, McGlumphy EA, et al. Biomechanical aspects of primary implant stability: a human cadaver study. Clin Implant Dent Relat Res 2009;11:113–119 18. Turkyilmaz I, Tözum TF, Tumer C. Bone density assessments of oral implant sites using computerized tomography. J Oral Rehabil 2007;34:267–272 19. Devlin H, Horner K, Ledgerton D. A comparison of maxillary and mandibular bone mineral densities. J Prosthet 1998;79:323–327 20. Dahlin C, Gottlow J, Linde A, et al. Healing of maxillary and mandibular bone defects using a membrane technique. An experimental study in monkeys. Scand J Plast Reconstr Surg Hand Surg 1990;24:13–19 21. Lazzara R, Siddiqui AA, Binon P, et al. Retrospective multicenter analysis of 3i endosseous dental implants placed over a five-year period. Clin Oral Implants Res 1996;7:73–83 22. Seong WJ, Kim UK, Swift JQ, et al. Correlations between physical properties of jawbone and dental implant initial stability. J Prosthet Dent 2009;101:306–318 23. Turkyilmaz I, Aksoy U, McGlumphy EA. Two alternative surgical techniques for enhancing primary implant stability in the posterior maxilla: a clinical study including bone density, insertion torque, and resonance frequency analysis data. Clin Implant Dent Relat Res 2008;10:231–237 24. Polizzi G, Rangert B, Lekholm U, et al. Branemark system wide platform implants for single molar replacement: clinical evaluation of prospective and retrospective materials. Clin Implant Dent Relat Res 2000;2:61–69 25. Calandriello R, Tomatis M, Vallone R, et al. Immediate occlusal loading of single lower molars using Branemark System Wide-Platform TiUnite implants: an interim report of a prospective open-ended clinical multicenter study. Clin Implant Dent Relat Res 2003;5(Suppl 1):74–80 26. Balleri P, Cozzolino A, Ghelli L, et al. Stability measurements of osseointegrated implants using Osstell in partially edentulous jaws after 1 year of loading: a pilot study. Clin Implant Dent Relat Res 2002;4:128–132

© 2014 Mutaz B. Habal, MD

Copyright © 2014 Mutaz B. Habal, MD. Unauthorized reproduction of this article is prohibited.

Does the time of osseointegration in the maxilla and mandible differ?

The objectives of the present study were to measure the implant stability quotient (ISQ) values at 3 different time points after the surgical insertio...
1MB Sizes 1 Downloads 5 Views