Effects of incisor repositioning on monkey periodontium after expansion through the cortical plate

The anterior teeth of five adult pigtail monkeys were moved lingually to correct a previously induced extreme labial displacement. (Roots had been moved through the labial bone to create bone dehiscence, loss of attachment, and gingival recession.) Eight months later, repositioning was performed with fixed appliances (Fig. 3). The teeth were retained in their more normal arch position for 5 months, after which clinical and histologic measurements were made of several periodontal parameters. The canines were not moved and served as reference teeth. Measurements were made to record changes in the levels of the gingival margin, the mucogingival junction, and the marginal bone relative to a fixed point on the tooth crowns, and the width of keratinized gingiva. Oxytetracycline was administered three times to label areas of osteogenesis in the periodontium. The incisors were retracted lingually a mean of 1.8 mm. The marginal bone level increased (moved coronally) a mean of 2.5 mm. and 3.1 mm. for maxillary and mandibular incisors, respectively (Table II). The tetracycline labels showed that osteogenesis occurred in the periodontium to a significant degree. The anchor canines had a loss of 1.1 mm. marginal bone (moved apically). Effects on gingival clefts and keratinized gingiva were slight. These observations demonstrate that in monkeys reapposition of labial bone can occur in a coronal direction, once teeth in extreme labial position with bone dehiscence and gingival recession are moved to a more normal environment. The effects on the periodontal soft tissues (width of keratinized gingiva, recession, attachment level) were, on the other hand, negligible in this study.