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Journal of Oral Science & Rehabilitation No. 4, 2017

P e r i i m p l a n t s o f t - t i s s u e a n d b o n e l e v e l s w i t h d i f f e r e n t i m p l a n t n e c k d e s i g n s significance level was set at P < 0.05. The sta- tistical methodology, with a confidence level of 95% and the median effect size to detect f = 0.25, reached a power of 0.81 for the con- trast of the interaction effect (homogeneity of bone loss in the groups). Results Fifty-five patients fulfilled the inclusion crite- ria. Patients who had undergone guided bone regeneration (n = 9), had immediate implants (n = 3), had missing information (n = 8) or failed to attend control visits (n = 6) were excluded. The final sample consisted of 27 partially eden- tulous patients, 12 women and 15 men (mean age: 63.5 ± 11.6), with a total of 51 dental implants: 13 patients with 28 implants (group A) and 14 patients with 23 implants (group B). In group A, 22% were smokers, and in group B, 44%. The implant sample was homoge- neous regarding the implant diameter, length and position, arch and antagonist dentition (Table 1). No significant differences were observed on evaluating clinical variables (Table 2). Higher PPD was measured in group B (5.3 ± 0.9 mm) compared with group A (4.8 ± 1.4 mm), with no statistically significant differences (P = 0.195). Group A showed lower BoP (47.1%) compared with group B (60%), although the odds ratio suggested an increased BoP risk with a TSA Advance implant (+27%), but there was insufficient statistical evidence to conclude a true effect (P = 0.524). Mucosi- tis was present in 14.3% in group B and 12.5% in group A, and the odds ratio suggested a higher risk of mucositis with a TSA Advance implant (14%), with no statistically significant differences between the groups (P = 0.916). The higher score on width of keratinized mucosa was found in group A (3.50 ± 2.44 mm) in comparison with group B (2.7 ± 2.4 mm); however, no statistically significant difference was found (P = 0.435). The mean radiographic marginal bone loss with the TSA implants was 0.57 ± 0.55 mm (range: 0.00–2.10 mm) and with the TSA Advance implants was 0.46 ± 0.49 mm (range: 0.00–1.61 mm), and the median was 0.47 mm for the TSA implants and 0.25 mm for the TSA Advance implants (Table 3). Despite the greater marginal bone loss around TSA implants, no statistically sig- nificant differences were observed (P = 0.217). Discussion This study evaluated and compared 2 implants with the same body and prosthetic connection, but with different neck designs after 3 years of follow-up to assess the influence of these vari- ables on periimplant tissue health and radio- graphic bone loss. The present study did not find statistical differences between the 2 implants on evaluating PPD, BoP, presence of mucositis, width of keratinized mucosa and marginal bone loss. It has been suggested that the initial mar- ginal bone level change occurs as an adaptation of the periimplant bone to the occlusal load. 23–26 In studies involving a follow-up of over year,1, 23–26 the greatest bone loss was observed during the first year and then bone loss gradually decreased. The addition of threads or microthreads up to the crestal module of an implant might provide a potentially positive contribution to bone– implant contact, as well as improve preservation of marginal bone.4, 20, 23, 27 Shin et al. observed that the most effective design for minimizing marginal bone loss during functional loading was a rough surface with microthreads at the implant neck.12 Abrahamsson and Berglundh drew a similar conclusion in an experimental study in dogs.28 They found that the degree of bone–implant contact within the marginal por- tion of the implants was significantly higher for the microthreaded implants compared with the implants with polished necks. Lee et al., in a well-controlled split-mouth study, also found that implants with microthreads showed signifi- cantly less bone loss compared with implants without them.2 However, although the studied implants were of the same brand and surface characteristics, they differed in their macrode- sign: one had a tapered neck and the other had a cylindrical design. In the present study, both implant models, although distinct in thread con- figuration, had a tapered design. Bratu et al. compared implants of the same brand and with the same dimensions, taper, titanium alloy and surface characteristics but different neck designs: one model with a polished neck and the other with a rough surface and microthreads up to its prosthetic platform.5 Unlike the present study, the implants with a rough surface and microthreads displayed statistically significantly less early marginal bone loss and greater bone level stability compared with the polished-neck implants. The results of Piao et al. demonstrated that the amount of marginal bone loss at 12 months of functional loading was significantly 20 Volume 3 | Issue 4/2017 Journal of Oral Science & Rehabilitation

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