Do functional orthodontic appliances stimulate mandibular growth in class II division 1 patients?
Background 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. Methods 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). Results 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 (ΔANB = − 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). Conclusions 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