Prediction of biomechanical complications in patients with implant supported fixed dental prostheses in different terms of functional loading

Abstract

Objective – to study features of biomechanical complications (structural fractures, loss of retention, screw loosening/fracture) of implant restorations in different terms of functional loading and work out preventive measures. Materials and methods. The results of prosthetic treatment with implant supported fixed dental prostheses were analyzed among 65 patients, who were treated between 2011 and 2016. There were 28 (47.1 %) men, 37 women (56.9 %), the average age of patients was 35.6 ± 12.7 years. All patients had small defects of dentition in posterior region without severe periodontal or general pathology. Prosthetic treatment was performed on two-staged osteointegrated “root form” implants with a screw design. According to the objective of the study all patients were divided into three groups depending on the period within implant placement and tooth extraction (6–8 month or more than 2 years), the terms of functional loading and usage of protective occlusal splits. The incidence of biomechanical complications and functional activity of masticatory muscles were detected. Results. The incidence of mechanical complications during 5-year period was 3.85 times higher in patients with long-term existing defects of dentition after tooth extraction and conventional prosthetic treatment with deferred occlusal loading (3 cases (15 %) of loss of retention, 5 cases (25 %) of veneering material fracture, 1 case (5 %) of abutment screw loosening and 1 case (5 %) of abutment screw fracture) in comparison to patients with early functional loading and shorter period after tooth extraction (1 case (4.3 %) of loss of retention and 2 cases (8.7 %) of veneering material fracture). Protective occlusal splints’ application and early functional loading in prosthetic treatment of patients with long-term existing defects of dentition after tooth extraction allowed to decrease the incidence of mechanical complications in 1.57 times in comparison to conventional treatment with deferred loading. Conclusions. The incidence of biomechanical complications of implant restorations is higher in patients with long-term existing defects of dentition after tooth extraction and deferred occlusal loading in comparison to cases of well-timed prosthetics and early functional loading. Protective occlusal splints are proved as effective preventive measures to decrease the incidence of mechanical complications of implant supported fixed dental prostheses and to induce faster normalization of masticatory activity.