[The relationships between different surgical approaches for maxillary sinus augmentation and implant failure and complications: a retrospective cohort study].

Purpose: To investigate the 5-year survival and complication rates of implants placed in grafted sinuses with different surgical approaches and analyze the causes for failure.

Methods: This study retrospectively observed the prognosis of patients who underwent maxillary sinus augmentation by means of lateral window technique(LWT) or transalveolar osteotomy technique (TOT) and simultaneously installed implants performed, in Hefei Stomatological Hospital. The primary predictor variables were surgical approaches, including LWT and TOT. The primary outcome measurement was the 5-year implant survival rate, complication rates and failure causes. Potential confounders included diabetes, age at surgery, gender, smoking habit, oral hygiene, tooth position, length and diameter of implants and type of prosthesis. Chi-square test and logistic regression analysis were performed with SPSS 21.0 software package.

Results: Fifty-nine patients (31 males and 28 females), installed with 93 implants, with a mean age of (61.3±10.1) years old, were enrolled. Over (5±1.2) years of follow-up, five implants failed, with a total survival rate of 94.6%. In detail, there were 3 failed implants in the LWT group and 2 failed implants in the TOT group, for a survival rate of 85.7% and 97.2%, respectively. Chi-square test showed that smoking habit (P=0.010), oral hygiene(P=0.037) as well as operative approach(P=0.040) were significantly associated with the final survival rates, multivariate logistic regression analysis displayed that smoking habit (OR=0.030, 95%CI: 0.002-0.493, P=0.014) was still associated with the finial survival rates. Surgical approach(P=0.025) was markedly related to causes for the failed implants. Of which, three (100%) failed implants in the LWT group was due to poor osseointegration and implant mobility 3 months after sinus augmentation, and 2(100%) in the TOT group was because of persistent peri-implantitis and loss of the graft or alveolar bone 4 years after sinus augmentation. Smoking habit was also significantly relevant to complication rates(P=0.014), and the occurrence incidence of controllable peri-implantitis in patient having a smoking habit was relatively higher, accounting for 6.8%(6/88), compared with patients without smoking habit. Significant relationship between surgical approaches and implant complications was not observed(P=0.051).

Conclusions: Different surgical approaches for maxillary sinus augmentation do not significantly correlate with implant survival rates and implant complications. However, surgical approach is markedly related to the causes of failed implants. Smoking will lead to a decreased implant survival rate and controllable peri-implantitis.