Effects of the Herbst Appliance With Skeletal Anchorage or Dental Anchorage, and Twin-Block Appliance in Class II Malocclusion: A Randomized Clinical Trial

2a. Background

The prevalence of the Angle Class II malocclusion is high, comprising almost half of known orthodontic problems (Silva Filho et al., 1990; Proffit et al., 1998). The Class II malocclusion is frequently responsible for negative aesthetic of the facial profile. This can result in psychosocial problems, principally in the Angle Class II, division I malocclusion because of the pronounced projection of the anterior superior teeth. This projection has also been related to fracture and avulsion of the anterior superior teeth.

Different types of appliances had been developed for the treatment of the Angle Class II malocclusion. Among these, functional orthopedic appliances have been used because they can correct Class II malocclusion with better improvement in the growth of the mandible when compared to headgears, which also can correct the problem, but with better restriction of the growth of the maxilla (Tulloch et al., 1997).

The Herbst appliance is a fixed functional orthopedic appliance that is often used because of its non-compliance-nature and the positive results achieved. Emil Herbst created the Herbst appliance in the 1910s (Pancherz; Ruf, 2008), but it was forgotten for decades. Only in the 1970s, Pancherz began a study of the Herbst appliance, and reported the positive results obtained in treatment of the Class II, division I malocclusion (Pancherz, 1979). Several subsequent studies of the Herbst appliance provided new scientific evidence of its benefits.

Nowadays, the Herbst appliance is often used in the treatment of Class II malocclusions, because of its efficiency (Bremen, Pancherz, 2008) and also because of the positive effects in orthodontic and orthopedic correction (Franchi et al., 1999). However, some investigators have stated that the correction of a Class II malocclusion is a result of anchorage loss, and could be responsible for negative effects on the lower incisors such as protrusion and gingival recession (Pancherz, 1979; Pancherz; Hansen, 1986; Pancherz; Hansen, 1988; Schütz et al., 2002; Vigorito; Yared et al., 2006; Dominguez, 2007).