Tissue Healing Around Dental Implants With Marginal Bone Defects With and Without Flap Elevation: An Experimental Study in Dogs
The technique of immediate implant placement after extraction has been conceived for preserving residual bone support and soft tissue morphology. Today, this procedure is still unpredictable and presents inconveniences for both the patient and the dentist. Therefore, the healing process around a dental implant placed into an extraction socket needs to be deeply investigated to increase the predictability of this surgical approach. The aim of the present investigation was to evaluate the healing of bone defects (fresh extraction sockets) after implant installation with flap elevation, and primary closure compared with implant installation without flap elevation. This study use histologic and histomorphometric analyses to evaluate tissue healing around dental implants with marginal bone defects with and without flap elevation 1 week, 4 weeks, and 12 weeks after implantation in the dogs. The main qualitative findings showed that after 1 week of implantation almost no bone repair was observed, and there was no significant difference between the 2 groups in terms of bone-healing performance, inflammatory infiltrates (slight to moderate grade), and bone resorption (moderate to marked grade) limited to the coronal portion of the implanted sites. The 2 groups with or without flap elevation behaved similarly at this point of implantation. Under the experimental conditions of this study, no biological differences were observed between the 2 groups with and without flap elevation in terms of crestal bone repair, inflammation, marginal bone loss, and soft tissue downgrowth. The qualitative differences observed might be imputable to fortuitous events. The histomorphometric measurements confirmed the qualitative trends observed. The limitations of this study, as with all animal studies, are its translational aspects. Investigation of the same topic in a human population by setting up a controlled, randomized, prospective trial including a sufficient amount of patients investigated according to the split-mouth method would be beneficial.
Histologic landmarks.
Figure 2. Adjusted effect of the flap approach compared with no-flap approach on bone-to-implant contact (BIC) percent measured at the 3 time points. The values given under the graph represent adjusted means for BIC; 95% confidence intervals are given in parentheses. Mixed regression models were adjusted for animal as a random effect and for other factors concerning the position of the implants in the mandible as fixed effects. Figure 3. Adjusted effect of the flap approach compared with the no-flap approach on bone area to total area ratio in the region of interest (BA/TA) percentage measured at the 3 time points. The values given under the graph represent adjusted means for BA/TA; 95% confidence intervals are given in parentheses. Mixed regression models were adjusted for animal as a random effect and for other factors concerning the position of the implants in the mandible as fixed effects. Figure 4. Adjusted effect of flap approach compared with no-flap approach on height of the connective tissue in contact with the implant surface (AJE-B) (in μm) measured at the 3 time points. The values given under the graph represent adjusted means for AJE-B; 95% confidence intervals are given in parentheses. Mixed regression models were adjusted for animal as a random effect and for other factors concerning the position of the implants in the mandible as fixed effects. Figure 5. Adjusted effect of flap compared to no flap approach on barrier epithelium (PM-AJE) (in μm) measured at the 3 time points. The values given under the graph represent adjusted means for this parameter; 95% confidence intervals are given in parentheses. Mixed regression models were adjusted for animal as a random effect and for other factors concerning the position of the implants in the mandible as fixed effects.
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