Tooth-Size Discrepancies in Patients Requiring Mandibular Advancement Surgery.
OBJECTIVE
Numerous studies have shown that tooth size is an important key to ideal occlusion. Bolton (Angle Orthod 28:13, 1958; 48:504, 1962) described a constant ratio between the widths of the upper and lower teeth that must be present to achieve an optimal occlusion. The purpose of this study was to determine the incidence of Bolton discrepancies in patients with Class II malocclusion scheduled for mandibular advancement surgery.


METHODS
This study included 126 patients (40 male, 86 female) with Class II malocclusion who had at least a mandibular advancement as part of their surgical treatment. The mesiodistal widths of the 6 anterior maxillary and mandibular teeth were measured on preoperative models using a caliper. The measurements were used to compute the anterior Bolton ratio.


RESULTS
Seventy-three of 126 patients (57.9%) were found to have an anterior Bolton ratio greater than the Bolton norm, indicating too much lower tooth mass compared with the upper mass or too little upper tooth mass compared with the lower mass.


CONCLUSIONS
Tooth-size discrepancies are common in patients requiring mandibular advancement surgery. This can make it difficult to advance the mandible into a solid Class I relation at the time of surgery. Bolton discrepancies should be considered when planning treatment with presurgical orthodontics. In addition, if necessary, the width of the lower incisors should be decreased or a space distal to the maxillary lateral incisors should be created to allow the establishment of a solid Class I canine occlusion at the time of surgery.
Former Resident, Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center at San Antonio, San Antonio, TX.
Andrew
A
Hanna
Professor and Chair, Department of Oral and Maxillofacial Surgery, University of Texas Health Science Center at San Antonio, San Antonio, TX. Electronic address: EllisE3@uthscsa.edu.
Edward
E
Ellis
D000066491:Clinical Decision-Making; D005260:Female; D006801:Humans; D008297:Male; D008312:Malocclusion, Angle Class II / Q000601:surgery* / Q000628:therapy; D019186:Mandibular Advancement; D009971:Orthodontics, Corrective / Q000379:methods; D011300:Preoperative Care / Q000379:methods; D014070:Tooth / Q000033:anatomy & histology*