Orthodontic space opening in patients with congenitally missing lateral incisors - Timing of orthodontic treatment and implant insertion

Objective: To determine the best time to begin orthodontic treatment for patients scheduled for implants to replace congenitally missing upper lateral incisors. The aim of timing is to maximize the amount of bone available for implant insertion and to improve incisors inclination. Materials and Methods: Seventy-three plaster casts of 14 patients with 26 missing lateral incisors were cross sectioned in the center of the planned insertion of the implant, and the implant profile was projected into the area at three different times: T1-beginning of orthodontic treatment, T2-end of orthodontic treatment, and T3-implant insertion. Deficiency of alveolar ridge volume needed for implantation was determined by Leica Quin analySIS software. Results: An increase of ridge-volume deficiency from 0.26 mm(2) at T1 to 3.77 mm(2) at T3 was found. During orthodontic treatment the incisors protruded about 9.4 degrees (differing from the O1-NA standard of 7.5 degrees). To ensure optimal esthetic and functional implantation results, time management concerning orthodontic treatment has to be done carefully. Conclusions: To avoid a high degree of alveolar bone atrophy and the risk of relapse and retreatment, orthodontic treatment involving tooth movement should not be initiated before the age of 13 years. Furthermore, it is important to maintain anchorage of the upper incisors because high incisor proclination causes extra-axial stress on the implant. An interdisciplinary approach is essential to provide the best treatment outcome.