Pulpal and periodontal reactions to orthodontic alignment of palatally impacted canines

The purpose of this study was to evaluate differences in periodontal and pulpal status, root length, and tooth alignment between contralateral maxillary lateral incisors, canines, and premolars in patients treated for unilateral impaction of maxillary canines. Clinical examinations were performed on 32 patients, average age 22 years 11 months and average posttreatment observation period 3 years 7 months. Probing attachment level was lower at the mesial and distal aspect of the previously impacted canine and at the distal aspect of the adjacent lateral incisor. Crestal bone height was lower at the mesial aspect of the previously impacted canine and at the distal aspect of the adjacent lateral incisor. The roots of the lateral incisors and premolars adjacent to the previously impacted canines were shorter. Pulpal obliteration was observed in six previously impacted canines (21%), and pulp necrosis in one previously impacted canine. The pulps of the remaining teeth appeared normal radiographically. A negative response to electric pulp testing was observed in eight previously impacted canines. Approximately 40% of the previously impacted canines exhibited noticeable relapse and were judged to be intruded, lingually displaced, mesially rotated, as well as discolored. Of the contralateral canines, 91% were normal in appearance. The previously impacted canine could be identified on posttreatment color slides in approximately 75% of the cases.

Rate of mesial translation of mandibular molars using implant-anchored mechanics

Retromolar dental implants served as anchorage to close first molar extraction sites in five adult patients. Rates of unidirectional space closure for mandibular second molars were assessed with periapical radiographs superimposed on anatomical landmarks and retromolar anchorage implants. Regression analysis revealed that mesial displacement of the midroot area of the leading root was less variable (r = 0.97) than for other landmarks on the same teeth: crown (r = 0.83), alveolar crest (r = 0.82) or apex (r = 0.90). When mesial root movement (uprighting) was the principal feature of the initial mechanics (4 of the 5 patients), mesial movement of the apex was about 0.60 mm/mo for the first 8 months and then decreased to about 0.34 mm/mo as the trailing (distal) root of the second molar engaged the relatively dense bone formed by the leading (mesial) root. During the last year of space closure, radiolucent foci were noted 1-2 mm ahead of the distal root. These data suggest: (1) sustained orthodontic translation is a physiological manifestation of bone modeling and remodeling throughout the adjacent alveolar process, and (2) rate of mandibular molar translation is inversely related to the apparent radiographic density of the resisting alveolar bone.