The Influence of Implant Diameter on Its Survival: A Meta-Analysis Based on Prospective Clinical Trials

• Localización: Journal of periodontology, ISSN 0022-3492, Nº. 4, 2014, págs. 569-580
• Idioma: inglés
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• Resumen

  • Background: The use of narrow-diameter implants has been proposed to restore small edentulous spans, thus avoiding extensive bone augmentation procedures and reducing the surgical complexity of implant rehabilitations. Although success rates of narrow-diameter implants have already been analyzed in the literature, to the best of the authors� knowledge, no meta-analysis based on prospective and randomized controlled trials has been performed. The aim of this study is to analyze the survival rates of narrow-diameter implants compared with standard or wide-diameter implants.

    Methods: An electronic search from three databases and a hand search in implant-related journals of studies published in English before September 1, 2012 were performed. Prospective human clinical studies with at least 10 implants and a follow-up period of 1 year were included in the meta-analysis. Implants were divided into two groups based on their diameters.

    Results: The initial search yielded 484 articles, of which 49 were evaluated in full text for eligibility. Finally, 16 studies were chosen and separated into two groups: 1) implants of diameter <3.3 mm (group 1) and 2) implants of diameter =3.3 mm (group 2). A meta-analysis performed for groups 1 and 2 showed survival rates of 75% and 87%, respectively.

    Conclusions: This meta-analysis showed that narrower implants (<3.3 mm) had significantly lower survival rates compared with wider implants (=3.3 mm). Other variables, such as type of prosthesis, implant surface, and timing of prosthetic loading, were found to have influenced the implant survival rates.

    Dental implants are excellent for replacing missing teeth. Not only do they demonstrate high success rates,1,2 they improve patients� quality of life by restoring lost function and esthetics. Compared with removable and fixed partial dentures, dental implants offer a fixed reconstruction of edentulous spans with no risk of biologic complications, such as caries, to natural teeth. As such, implant-supported or retained prostheses have indications ranging from replacing a single tooth to restoring full-arch edentulous spans.3 Despite the benefits of dental implants, their use is confined to areas with adequate bone volume. This serves as a limitation because bone remodeling after tooth loss frequently renders the edentulous site unsuitable for implant placement.4 Loss of horizontal ridge width occurs more frequently and to a greater extent compared with vertical bone loss after tooth extraction.5 Several options, such as advanced bone-grafting procedures6 before or simultaneously with implant placement and use of narrow7 implants, have been proposed to overcome this limitation.

    Multiple studies in the literature attempted to classify small implants by their diameter.8-10 Saadoun and Le Gall9 considered 3.8 mm as standard diameter and narrow implants as =3.7 mm. In contrast, Degidi et al.10 classified =3-mm-diameter implants as narrow-diameter implants, whereas Davarpanah et al.6 considered narrow implants as those with diameters from 3.0 to 3.4 mm.

    Similarly, Romeo et al.11 classified small-diameter implants as 3.3-mm implants, with 4.1 mm being the standard-diameter implants. Quek et al.8 attempted to classify implants into mini (<2.9 mm), small or narrow (3 to 3.4 mm), regular (3.75 to 4 mm), and wide (5 to 6 mm). Therefore, implant diameters ranging from 1.8 to 3.3 mm12-15 have been categorized as narrow implants. In addition, huge variability existed among the studies, making it even more difficult to establish the definition of small- and standard-diameter implants. This research showed that there is no universal classification of implant diameters.

    Multiple studies found that narrow implants shared similar success and survival rates as regular and wide implants.11,16 A recent review reported that small-diameter implants have survival rates of >90%.16 However, there is no meta-analysis evaluating the success and survival rates of narrow implants. Therefore, this meta-analysis aimed to explore the success and survival rates of narrow implants based only on prospective studies. To obtain statistically significant results, implant diameter is grouped as <3.3 and =3.3 mm for this analysis.