Abstract
The objective of this article was to investigate the perception of esthetic changes in the facial profile of bilateral Class II patients treated with the Modified Thurow Appliance for extraoral treatment. Silhouettes were traced of profiles of patients who initially presented a bilateral Class II molar relationship and who, post-treatment, presented molars in a Class I relationship. Three groups were formed: the first composed of patients with maxillary protrusion (SNA >84°), the second with maxillary retrusion (SNA <80°), and the third with a well-positioned maxilla (SNA 80-84°). A panel of 200 lay evaluators judged the profile esthetics by a randomized drawing of the silhouettes. The multiple analysis results showed that the profile esthetic scores for the three positions of the maxilla were greatly influenced by significant interactions with the characteristics (like sex and age) of the evaluators: retrusive maxilla (Score *Age Group, p < 0.001), normal maxilla (Score *Sex, p = 0.024; Score *Age Group, p = 0.050) and protrusive maxilla (Score *Age Group, p < 0.001). It was observed that the profile of Class II patients with protrusion, normal relationship and retrusion of the maxilla, improved in their esthetic post-treatment result; however, the evaluators showed greater satisfaction with the groups of protrusion and normal position of the maxilla. The Modified Thurow Appliance provided significant improvements in the esthetics of the profile of patients who presented protrusion and normal position of the maxilla. However, its use was not the best treatment option for patients with maxillary retrusion.
Highlights
Angle’s Class II malocclusion is characterized by a dental discrepancy in which the mesial groove of the lower first permanent molar articulates posterior to the mesiobuccal cusp of the first permanent maxillary molar
In the case of the well-positioned and the protrusive maxilla, the esthetic profile evaluation scores were higher for the post-treatment silhouettes, indicating that the evaluators considered the final result of the treatment as attractive (Table 3)
Multiple analysis showed that the esthetic profile scores for the three maxilla positions were influenced by significant interactions with the evaluators’ characteristics: retrusive maxilla (Score *Age Group, p < 0.001), normal maxilla (Score *Sex, p = 0.024; Score *Age Group, p = 0.05) and protrusive maxilla (Score *Age Group, p < 0.001)
Summary
Angle’s Class II malocclusion is characterized by a dental discrepancy in which the mesial groove of the lower first permanent molar articulates posterior to the mesiobuccal cusp of the first permanent maxillary molar. It can be characterized by a maxillomandibular skeletal discrepancy in the anteroposterior direction, by maxillary protrusion, by mandibular retrusion or by a combination of these factors. The incidence of this malocclusion ranges from 35% to 42%, and may attain up to 50% of the clinical cases treated by orthodontists.[1,2]. In regard to extraoral orthopedic appliances, there are those made with an outer facial arch attached to rings cemented to the molars, and there is the Thurow Appliance, where the outer facial arch is attached to acrylic resin adapted to the occlusal surfaces of the teeth.[10]
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