Effect of the mesiodistal cantilever on implant-supported single crowns on biological and technical complications: A retrospective study.

PURPOSE: To retrospectively evaluate the influence of mesiodistal intra-coronal cantilever width of implant-supported single crowns on the implant and restoration complication-free survival rate and the peri-implant soft and hard tissues. MATERIALS AND METHODS: A total of 142 patients with 179 implants in the posterior region were evaluated. The implants were divided into three groups according to intra-coronal cantilever width (Group 1, </= 1 mm; Group 2, 1 mm intra-coronal cantilever width 2 mm; Group 3, >/= 2 mm). Marginal bone loss, complications and clinical parameters were used to evaluate the influence of intra-coronal cantilever width on implant-supported single crowns. RESULTS: Group 1 included 95 implants, Group 2 was composed of 27 implants and Group 3 comprised 57 implants. A univariate Cox proportional hazards model, assessing implant complication-free survival, indicated a higher complication rate for Group 3 compared to Group 1 (P = 0.009). Furthermore, the marginal bone loss on the cantilever side over the short-term and medium- to long-term follow-up period indicated that intra-coronal cantilever width >/= 2 mm may be considered a risk factor. From a clinical perspective, compared with Group 3, Groups 1 and 2 exhibited lower incidence rates of bleeding on probing during the medium- to long-term follow-up period (P = 0.003). CONCLUSIONS: Despite its limitations, the present study shows that posterior single implant crowns with mesiodistal intra-coronal cantilevers equal to or higher than 2 mm will present greater marginal bone loss, complications and tissue inflammation.