An evaluation of the relative contribution of incisor inclination, overjet and soft tissue relationships on the decision to undertake orthodontic camouflage

Abstract

Objective: To evaluate the relative contribution of incisor inclination, overjet and soft tissue relationships on the decision to undertake orthodontic camouflage. Design: A cross-sectional questionnaire-based study. Setting: Queen Mary University of London, United Kingdom. Participants: Forty-three specialist orthodontists based in the United Kingdom. Method: Photographs (profile view, facial view and three-quarter view) of a male subject with a Class II skeletal pattern were taken. These photographs were digitally manipulated to form eight videos using a digital animation application (Procreate®) changing the antero-posterior position and inclination of the maxillary incisors to reflect changes in the overjet. The soft tissue effects associated with overjet reduction were also simulated. An online questionnaire containing the videos was developed using the JiscTM survey software tool. The questionnaire was sent via a global email through the British Orthodontic Society (BOS) to all specialist orthodontists within the United Kingdom. Participants were asked to answer questions relating to all eight videos. Results: This study has concluded that the degree of maxillary incisor inclination combined with the nasolabial angle and the slope of the upper lip provide a large contribution in an orthodontist’s decision to undertake orthodontic camouflage of a Class II case. The majority of respondents (46.3%) stated that the soft tissue profile is the most important aspect when undertaking orthodontic camouflage for cases with an increased overjet. The nasolabial angle was the most important feature for respondents when undertaking orthodontic camouflage (27.9%). This was followed by the slope of the upper lip (20.9%) and the inclination of the maxillary incisors (18.6%). In terms of skeletal and dental features, 11 out of 43 respondents, the majority (52%) ranked the degree of mandibular retrognathia assessed clinically as being the most important factor when undertaking orthodontic camouflage for Class II cases. Overall, the majority of respondents were in agreement that a subject with an overjet over 7mm has a less attractive facial profile. Due to the severity of the overjet, the incisor inclination had little influence on a treatment planning decision, as the majority of orthodontists felt that these cases required a combined orthodontic-surgical approach to achieve full correction of the malocclusion without detrimental soft tissue effects.