It has been argued by a vocal coterie of disaffected dentists that premolar extraction, incisor retraction, and "backward-pulling" mechanics conspire to "distalize" the condyles and, pari passu, to produce craniomandibular dysfunction. Given the gravity of this conjecture, it seemed appropriate to test the predictions it generates in a sample of patients of the type most often said to be at risk: 42 "edgewise" patients with Class II, Division 1 malocclusions, treated in conjunction with the extraction of two maxillary first premolars. Regional and anterior cranial-base cephalometric superimpositions were used to quantify the individual components of the molar and overjet corrections, to measure both at the chin and condyles the mandibular displacement seen during treatment, and to examine the extent to which this displacement is related to the correction of maxillary incisor protrusion. Although the present patients underwent marked upper incisor retraction (on average, about 5 mm), lip retraction was much less pronounced, and 70% of the sample showed a net forward displacement of mandibular basal bone. Significantly, changes in condylar position were not correlated with incisor retraction, as the "functional orthodontists" would have it, but rather with the changes in the buccal occlusion and the growth of the maxilla. Thus, 30% of the patients who showed evidence of distal displacement were generally nongrowing patients who underwent more than average anchorage loss in the mandible and less than average loss in the maxilla. Regardless of the direction of basal displacement, however, condylar remodeling apparently served to stabilize the spatial position of surface landmarks (e.g., condylion), an observation that underscores the futility of using any type of serial radiograph to assess changes in condylar position in the growing, unimplanted patient.
|Original language||English (US)|
|Number of pages||9|
|Journal||American Journal of Orthodontics and Dentofacial Orthopedics|
|State||Published - Jan 1992|
ASJC Scopus subject areas