Mini-implants in orthodontics: A systematic review of the literature
Reint Reynders,a Laura Ronchi,a and Shandra Bipatb Milan, Italy, and Amsterdam, The Netherlands Introduction: In this article, we systematically reviewed the literature to quantify success and complications encountered with the use of mini-implants for orthodontic anchorage, and to analyze factors associated withsuccess or failure. Methods: Computerized and manual searches were conducted up to March 31, 2008, for clinical studies that addressed these objectives. The selection criteria required that these studies (1) reported the success rates of mini-implants on samples sizes of 10 implants or more, (2) gave a deﬁnition of success, (3) used implants with a diameter smaller than 2.5 mm, and (4) appliedforces for a minimum duration of 3 months. Factors associated with implant success were accepted only if potentially inﬂuencing variables were controlled. The Cochrane Handbook for Systematic Reviews of Interventions was used as the guideline for this article. Results: Nineteen reports met the inclusion criteria, but deﬁnitions of success, duration of force application, and quality of themethodology of these studies varied widely. Rates of primary outcomes ranged from 0% to 100%, but most articles reported success rates greater than 80% if mobile and displaced implants were included as successful. Adverse effects of miniscrews included biologic damage, inﬂammation, and pain and discomfort. Only a few articles reported negative outcomes. All proposed correlations between clinical success andspeciﬁc variables such as implant, patient, location, surgery, orthodontic, and implant-maintenance factors were rejected because they did not meet the selection criteria for controlling those variables. Conclusions: Mini-implants can be used as temporary anchorage devices, but research in this ﬁeld is still in its infancy. Interpretation of ﬁndings was conditioned by lack of clarity and poormethodology of most studies. Questions concerning patient acceptability, rate and severity of adverse effects of miniscrews, and variables that inﬂuenced success remain unanswered. This article includes a guideline for future studies of these issues, based on speciﬁc deﬁnitions of primary and secondary outcomes correlated with speciﬁc operational variables. (Am J Orthod Dentofacial Orthop2009;135:564.e1-564.e19)
sseointegrated implants are considered reliable sources of anchorage for orthodontists.1-6 However, the large size of these implants limits their usage. To overcome this problem, mini-implants were developed.7-13 Their advantages, in addition to size, include minimal anatomic limitations, minor surgery, increased patient comfort, immediate loading, and lower costs.11-15Because these devices are used for speciﬁc time periods, mostly rely on mechanical retention, and do not always osseointegrate, other terms such as miniscrews, miniscrew implants, microscrews, and temporary anchorage devices have been used.16,17 There is no general
Private practice, Milan, Italy. Research associate, Departments of Radiology, Epidemiology and Biostatistics, Academic MedicalCenter, University of Amsterdam, Amsterdam, The Netherlands. The authors report no commercial, proprietary, or ﬁnancial interest in the products or companies described in this article. Reprint requests to: Reint Reynders, Via Matteo Bandello 15, 20123, Milan, Italy; e-mail, email@example.com. Submitted, April 2008; revised and accepted, September 2008. 0889-5406/$36.00 Copyright Ó 2009 bythe American Association of Orthodontists. doi:10.1016/j.ajodo.2008.09.026
agreement on the nomenclature.18,19 We used the term ‘‘mini-implant’’ in the title, because it is currently the most frequently used in the orthodontic literature. Many mini-implants are now available, and orthodontists are trying to incorporate them in various clinical situations. However, with the introduction of new...