Do functional orthodontic appliances stimulate mandibular growth in class II division 1 patients?

Abstract

The effectiveness of functional orthodontic treatment and the resulting skeletal response have always been discussed controversially. Therefore a systematic review of the literature was conducted on this subject with special attention to mandibular growth. Based on Cochrane Collaboration® recommendations a research of the literature was carried out. The meta-analysis examined 3 appliances for the period between 1996 and 2008: Herbst appliance (HA), activator (AC) and headgear-activator (HAC). The cephalometric parameters under review were SNA, SNB, ANB, OLp-A, OLp-Pg (distances between the occlusal line perpendicular and A/Pg), Co-Gn and the PPl angle (angle between ANS-PNS and N-S plane). A total of 11 studies were considered. Maxillary changes through SNA and OLp-A were most prominent for the HAC (- 1.93°mm and - 2.6 mm, respectively). Mandibulary changes through SNB and OLp-Pg were almost identical for all 3 appliances. The HAC showed the greatest intermaxillary effect (∆ANB = - 2.54°) although a decrease in SNA accounted for most of it. The biggest increase in the vertical parameter PPl angle and the mandibular length Co-Gn were recorded for the AC (+ 2.25°mm and + 4.01 mm, respectively). The HA, AC and HAC appliances significantly influenced the evaluated cephalometric parameters. The desired forward placement of the mandible is clinically inferior and always accompanied by a constraint of the maxilla. Therefore the decision to treat with functional appliances has to be carefully evaluated based on the benefits and possible side-effects for the individual patient.