Since the 1930s many orthodontists, mainly in Germany, believed to control the growth of the jaws by orthodontic appliances. Especially regarding the retrusion of the lower jaw functional orthodontic appliances were used for treatment although the smart ones among the orthodontists doubted the influence on skeletal growth. Since 1970 fixed appliances have been used for treatment of mandibular retrusion, which are supposed to protrude the lower jaw. The prototype of these appliances is the Herbst® appliance. Many orthodontists believed that these appliances could control the mandibular growth efficiently because of their permanent impact on the jaws for many months.
But the question is, whether fixed braces like the Herbst® appliance do really have a significant impact on facial growth. The authors of a recent systematic review have therefore collected data from the whole orthodontic literature of the last decades. Nine studies of fixed functional appliances (FFAs) were included. 244 patients and 174 untreated controls with Class II malocclusions were included in these studies. Their mean age was 13,5 years. The authors found little cephalometric effects.
FFAs were found to induce a small reduction of SNA angle (MD = -0.83 degree/year) and a small increase of SNB angle (MD = 0.87 degree/year). Regarding the relation between upper and lower jaw a moderate decrease of ANB angle (MD = -1.74 degree/year) was shown. These annualised effects are a bit better than those of removable orthodontic appliances, but the latter are used for a considerably longer treatment duration. Finally fixed functional appliances are more efficient because of their shorter therapy duration, but in comparison to removable appliances they don’t show much effect on the growth of the facial skeleton either. The magnitude of their effects on facial growth is well below a level that would be noticeable – therefore clinically irrelevant. However, all studies proved that FFA treatment resulted in significant dentoalveolar changes. The authors pointed out that “long-term effectiveness of FFAs could not be assessed due to limited evidence“.
Long-term studies which have been published so far point out that skeletal changes induced by FFAs found immediately after therapy some years later regularly are undetectable. The authors conclude that FFAs are effective for treatment of mandibular retrusion, but their effects are mainly restricted to tooth movement. Like with removable functional appliances treatment effects are rather dentoalveolar than skeletal.
Reference: Zymperdikas VF, Koretsi V, Papageorgiou SN, Papadopoulos MA. Treatment effects of fixed functional appliances in patients with Class II malocclusion: a systematic review and meta-analysis. Eur J Orthod. 2016 Apr;38(2):113-26. doi: 10.1093/ejo/cjv034. Review. PubMed PMID: 25995359; PubMed Central PMCID: PMC4914762.
Comment: Such systematic reviews are of particularly high value because they clearly summarize the whole knowledge for answering special questions. By reading these systematic reviews physicians can save effort and time because they don’t have to search for the individual studies. The authors of systematic reviews have to prove accuracy, effort and honesty. According to conducting systematic reviews you can find well-known guidelines here: www.prisma-statement.org. It’s a tragedy the numerous systematic reviews published in English are hardly noticed by German orthodontists. No wonder that German orthodontists still recommend treatment with FFAs and RFAs in order to increase the length of jaws. However, well-informed young patients and their parents can know better by now.