Impaired osseointegration of dental implants associated with orthognathic surgery: Possible regional acceleratory phenomenon

Background: Regional acceleratory phenomenon (RAP) is demonstrated to decrease regional bone mineral density and accelerate bone turnover. Hypothesizing that RAP can negatively affect the osseointegration of biomaterials, this study aimed to investigate the possible influence of the RAP on dental implant osseointegration. Materials and Methods: Orthognathic surgery, one of the major surgeries on oral and maxillofacial region was set as intervention for RAP. Considering that RAP exerts its physiologic effects until 4 months after noxious stimuli, patients were classified according to the time interval between orthognathic surgery and dental implant installation; group I was designated to patients who had implant installation within 4 months from orthognathic surgery. Group II were those with installation after 4-12 months and group III was longer than 12 months. Radiographic and clinical evaluations of dental implants including peri-implant marginal bone changes (MBR), implant stability, cumulative survival rates were analyzed. Results: A total of 54 patients with 106 implants (mean follow-up of 72.6 months) were included in the study. MBR was significantly higher in group I (2.62 ± 0.91 mm) and II (2.25 ± 0.95 mm) compared to that of group III (0.94 ± 0.90 mm) at last follow up (P < 0.05) and this group difference over time was also significant (P < 0.001). Compared to group III, groups I and II exhibited lower ISQ values and higher biological complications including peri-implantitis and peri-implant gingivitis (P < 0.05). Group I showed significantly low-cumulative survival rate (89.2%; implant-level) compared to groups II and III. Conclusions: In this study, impaired osseointegration of dental implants was demonstrated associated with orthognathic surgery. Micro-environmental changes of hard tissue induced by major surgery on the jaw showed deteriorating effects on integrity of biomaterial osseointegration. Special considerations should be addressed for ideal treatment results and prognosis.