CRANIOMAXILLOFACIAL DEFORMITIES/COSMETIC SURGERY A Classification System for Conditions Causing Condylar Hyperplasia Larry M. Wolford, DMD, * Reza Movahed, DMD,y and Daniel E. Perez, DDSz A classification system was developed to place patients with condylar hyperplasia (CH) into categories based on histology, clinical and imaging characteristics, effects on the jaws and facial structures, and rate of occurrence. Four major categories were defined. CH type 1 is an accelerated and prolonged growth aberration of the ‘‘normal’’ mandibularcondylar growth mechanism, causing a predominantly horizontal growth vector, resulting in prognathism that can occur bilaterally (CH type 1A) or unilaterally (CH type 1B). CH type 2 refers to enlargement of the mandibular condyle caused by an osteochondroma, resulting in predominantly unilateral vertical overgrowth and elongation of the mandible and face. One of the forms has predominantly a vertical growth vector and condylar enlargement, but without exophytic tumor ex- tensions (type 2A), whereas the other primary form grows vertically but develops horizontal exophytic tumor growth off of the condyle (CH type 2B). CH type 3 includes other rare, benign tumors and CH type 4 includes malignant conditions that originate in the mandibular condyle causing enlargement. The order of classification is based on occurrence rates and type of pathology, where CH type 1A is the most commonly occurring form and CH type 4 is the rarest. This classification system for CH pathology should help the clinician understand the nature of the pathology, progression if untreated, recommended ages for surgical intervention to minimize adverse effects on subsequent facial growth and development in younger patients, and the surgical protocols to comprehensively and predictably treat these conditions. Ó 2014 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 72:567-595, 2014 Hyperplasia indicates the increased production and growth of normal cells in a tissue or organ without an increase in the size of the cells, but the affected part becomes larger yet retains its basic form. Condy- lar hyperplasia (CH) is a generic term describing con- ditions that cause excessive growth and enlargement of the mandibular condyle. There are many suggested etiologies of CH, including neoplasia, trauma, infec- tion, abnormal condylar loading, 1 and aberrant growth factors. These condylar pathologies can adversely af- fect the size and morphology of the mandible, alter the occlusion, and indirectly affect the maxilla, with the resultant development or worsening of dentofacial deformities, such as mandibular prognathism; unilat- eral enlargement of the condyle, neck, ramus, and body; facial asymmetry; malocclusion; and pain. Some CH pathologies occur more commonly within particular age ranges and genders. Identifying the spe- cific CH pathology will provide insight to its progres- sion if untreated; the clinical, imaging, and histologic characteristics; and treatment protocols proved to eliminate the pathologic processes and provide opti- mal functional and esthetic outcomes. Adams 2 in 1836 and Humphry 3 in 1856 were 2 of the first to de- scribe and treat CH with a condylectomy. This report presents a simple but encompassing classification for CH. The acronym CH for this classifi- cation includes conditions that create excessive growth and enlargement of the condyle that can cause alterations in the bony architecture of the mandible, malocclusion, and dentofacial deformity. This classifi- cation excludes congenital deformities (eg, hemifacial hypertrophy, Sturge-Webber syndrome, fibrous dyspla- sia) and endocrinal conditions (eg, acromegalia) that Received from the Texas A&M University Health Science Center, Baylor College of Dentistry, Baylor University Medical Center, Dallas, TX. *Clinical Professor, Department of Oral and Maxillofacial Surgery. yFormer Fellow, Private Practice, Saint Louis, MO. Assistant Professor, Saint Louis University, Department of Orthodontics, MO. zFormer Fellow, Assistant Professor at Department of Oral and Maxillofacial Surgery, UT Dental School, San Antonio, TX. Conflict of Interest Disclosures: None of the authors reported any disclosures. Address correspondence and reprint requests to Dr Wolford: 3409 Worth Street, Suite 400, Dallas, TX 75246; e-mail: lwolford@ drlarrywolford.com Received May 13 2013 Accepted September 2 2013 Ó 2014 American Association of Oral and Maxillofacial Surgeons 0278-2391/13/01141-5$36.00/0 http://dx.doi.org/10.1016/j.joms.2013.09.002 567