by Ann-Marie C. DePalma, CDA, RDH, MEd, FAADH
As defined by Wilkins, orthodontics is the area of dentistry concerned with the diagnosis, supervision, guidance, and treatment of the growing and mature dentofacial structures – including conditions that require movement of the teeth – and the treatment of malrelationships and malformations of the craniofacial complex.
As dental hygienists, we are familiar with Dr. Edward Angle‘s classifications of occlusal relationships. Dr. Angle is considered the “father of modern orthodontics,” who designed a classification system in the late 1890s to early 1900s based on the first molar as the key to occlusion. As a review,normal occlusion is considered when the mesiobuccal cusp of the maxillary first molar occludes with the buccal groove of the mandibular first molar. Deviations from this norm are considered malocclusions.
Class I malocculsion has normal molar relationships present, but other teeth may be crowded, rotated, or have excess spacing. In Class II malocclusion, the maxillary first molar is forward of the normal molar relationship so that the mesiobuccal cusp of the maxillary first molar is mesial to the buccal groove of the mandibular first molar. Class II malocclusions are further divided into Division 1 and Division 2. With Division 1, the maxillary incisors are protruding, while in Division 2 the maxillary central incisors retrude and the lateral incisors protrude. Class III malocclusions present with the mesiobuccal cusp of the maxillary first molar distal to the buccal groove of the mandibular first molar. Additionally, occlusal discrepancies including anterior or posterior open bites, increased overbite and overjet, crossbites, and diastemas may be present.