Implant Abutment Screw Loosening: A Review of Effective Factors

One of the prevalent complications of dental implants is screw loosening. It has been revealed that screw loosening is a matter of concern for both manufacturers and dental professionals, and this complication imposes more time and money to clinician and patient. The clinical long-term success of implant restorations depends, in part, on the actions to minimise the parameters causing screw loosening. This review article aims to throw light on explaining these effective factors and parameters that determine screw stability. Literature based-search was performed to find related articles till December 2018 using EMBASE, Google Scholar and MEDLINE. Search terms used were Implant-abutment (I/A) connection/interface, screw-joint stability, lubricants (such as chlorhexidine (CHX), blood and saliva), mechanical and biological factors (such as contamination, micro-gap formation, settling effect, metal fatigue and abutment screw coating and loosening) in implant functional failure. Results were limited to papers available in English. The references of all related literature were also searched for further citations. A large number of factors including lubricants and mechanical factors have been proposed to have the potential of increasing screw loosening. In-vitro and in-vivo studies concerning the detailed role of biomechanical agents in incidence of screw loosening may be interesting area to improve the existing knowledge in this field. This paper presents the comprehensive insight into effective factors in incidence of screw loosening.