Scientific rationale for Clinical Practice Guidelines (part 2): what is the effectiveness of retention devices?

Introduction: Retention is the set of means, processes or devices that contribute to maintaining the teeth in the position and the arches in the shape given by the orthodontic treatment. The main objective is to propose Clinical Practice Guidelines (CPG) on orthodontic retention by answering four main questions. This article provides the first part of the answer to the second question: How effective are the retention devices?
Materials and Methods: A literature review was carried out after a bibliographic search using keywords in bibliographic databases and in international organizations websites.
Results: 652 articles were selected after the bibliographic search, and only 53 met the inclusion criteria. These were used to develop the CPG full-text and guidelines.
Discussion: Ten CPGs were issued from this review, divided into 12 items, 10 of which are grade C and 2 are expert agreements.
Conclusion: Forty CPGs about orthodontic retention were proposed from this literature review, 10 of which are presented in this second part. In the mandible, fixed retention provides better stability than removable retention and 6-tooth retention is more effective in maintaining incisal alignment. Fixed and removable retention are equivalent in maintaining extraction spaces and arch length. Removable retention allows for minimal tooth movement and establishment of occlusal contacts.