Using 3D digital models to establish alveolar morphotype.

BACKGROUND AND AIMS: To propose a classification of alveolar morphotype, and assess a relationship between extraction/non-extraction orthodontic treatment and changes to the alveolar process.

METHODS: Seventy-five subjects (mean age = 23.2, SD = 5.1) were selected. Areas of the sections of the alveolar process (ASAP) at three different levels (0, 2, and 4 mm) were measured on pre- and post-treatment 3D digital models. Method reliability was analyzed using Dahlberg's formula, intraclass correlation coefficient (ICC), and paired t-tests.

RESULTS: The mean ASAP was smallest at level 0 and largest at level 4. Pre-treatment ASAP < 773 mm², < 863.9 mm², and <881.1 mm² at levels 0, 2, and 4 mm, respectively, should be described as a "thin" alveolar morphotype. Regression models showed that pre-treatment ASAP was a predictor of the change of the alveolus during treatment only at level 2.

CONCLUSIONS: Patients for whom pre-treatment ASAP is < 773 mm², < 863.9 mm², and < 881.1 mm² at levels 0, 2, and 4 mm, respectively, should be described as having a "thin" alveolar morphotype. In these patients, extraction treatment, associated with a decrease in the alveolus area, should be exercised with caution.