Survival Rates of Narrow Diameter Implants

Abstract

Endosseous implants are used for the support of prostheses ranging from single tooth to complex full mouth rehabilitations. Longitudinal, retrospective and case series reports have shown the cumulative success for endosseous implants supporting various forms of prostheses to be highly successful. Frequently, bone grafting for sinus and ridge augmentation is performed to improve the osseous dimensions to accommodate the placement of dental implants in the ideal prosthetic position. Implants of smaller dimensions have become increasingly popular since implant site development, requiring bone grafting can be circumvented for the atrophied or reduced edentulous site. Reduced implant diameter and length result in proportional decreases in implant surface area. This confers a decreased implant-to-bone contact area. Biomechanically, implants of smaller dimensions have higher crestal strain, lower pull out force and lower structural integrity. Theoretically, this can translate to lower clinical success rate for implants of lesser dimensions. The purpose of this paper was to perform a systematic review of the available literature on the efficacy of narrow diameter implants by comparing implant survival rates. Electronic and manual search were conducted using Ovid and the bibliographies of relevant articles. Summary statistics and meta-analysis were performed using commercially available software. A total of 23 articles fulfilled the inclusion and exclusion criteria and were used for final data analysis. The result of this systematic review showed the survival rates and rate of marginal bone loss for narrow diameter implants to be comparable to regular diameter implants both in short and long term studies. Meta analysis of the data showed a significant difference in the survival rate between short (< 10mm) and regular length (≥ 10mm) narrow diameter implants, favoring regular length narrow diameter implants. Thus, it can be concluded that dental implants of smaller dimensions should be used with caution. Although clinical successes have been reported for both short or narrow diameter implants, the clinical effect of both dimensional factors, when combined is still not known. The use of shorter implants with diameter of less than 3.75mm cannot be substantiated.