Effect of posterior implant restorations on adjacent teeth and tissues: A case–control study

Introduction: Dental implants are an artificial substitute for extracted or missing teeth in the oral cavity and are valuable for improving dental health and quality of life. While many studies on implants can be found, few studies examine their effects on adjacent teeth and tissues. The study aimed to examine complications of teeth adjacent to dental implants in the posterior region. Methods: In this retrospective case–control study, clinical data of patients treated with implants in the posterior segment were extracted from the medical records in a single community dental clinic between January 9, 2010 and January 9, 2020. The patients were examined clinically and radiographically every 6 months. Data on the adjacent teeth to the dental implants were collected and divided into two groups, complications (“study group”) versus no-complications (“control group”). Multivariate logistic regression analysis was performed to find a possible correlation between the complications and the variables checked, followed by checking specific variables in the complication group. Results: A total of 1072 patients were included in the study. There were 179 patients (16.7%) with complications in adjacent teeth, while 893 patients had no documented complications. Predisposing factors for secondary caries were smoking (OR = 2.2, CI = 1.3–3.8) and a higher number of implants (OR = 1.6, CI = 1.1–2.5). Tooth crack and tooth fracture were analyzed together and found to be related to osteoporosis (OR = 8.9, CI = 2.9–27.6), whereas males were more prone to teeth fracture (OR = 2.8, CI = 1.1–7.4). Tooth mobility was related to a higher number of implants (OR = 16.5, CI = 3.7–73.8). Further analyzing the complication group solely, there was a statistical significance for age in primary caries and tooth mobility (p = 0.045). In addition, a higher number of implants was more prevalent with tooth mobility (p = 0.002), wider implant platform was more significant with primary caries (p = 0.012), and periodontal Stage III was more prone to tooth mobility (p < 0.001). The distance between the implant and adjacent tooth was also statistically significant—close proximity with tooth mobility and high distance with dental caries (p = 0.04). Conclusions: We found a relatively high rate of complications in teeth adjacent to dental implants. Secondary caries was the most common complication. Good understanding and proper position of the implants is essential to avoid adjacent teeth complications.