Stable region for maxillary dental cast superimposition in adults, studied with the aid of stable miniscrews

Structured Abstract Authors - Chen G, Chen S, Zhang XY, Jiang RP, Liu Y, Shi FH, Xu TM Objectives - To identify a stable and reproducible reference region to superimpose serial maxillary dental models in adult extraction cases. Setting and Sample Population - Fifteen adult volunteers were enrolled. Methods - To reduce protrusion, bilateral maxillary first premolars were extracted in all volunteers. Each volunteer received six miniscrews, including two loaded miniscrews used to retract anterior teeth and four unloaded miniscrews. Impressions for maxillary models were taken at T1 (1 week after miniscrew placement) and T2 (17 months later). Dental models were created and then scanned using a laser scanner. Stability of the miniscrews was evaluated, and dental models were registered using stationary miniscrews. The palatal region, where deviation was within 0.5 mm in all subjects, was determined to be the stable region. Reproducibility of the new palatal region for 3D digital model superimposition was evaluated. Results - Deviation of the medial 2/3 of the palatal region between the third rugae and the line in contact with the distal surface of the bilateral maxillary first molars was within 0.5 mm. Tooth movement of 15 subjects was measured to evaluate the validity of the new 3D superimposition method. Displacements were 8.18 +/- 2.94 mm (central incisor) and 2.25 +/- 0.73 mm (first molar) measured by miniscrew superimposition, while values of 7.81 +/- 2.53 mm (central incisor) and 2.29 +/- 1.03 mm (first molar) were measured using the 3D palatal vault regional superimposition method; no significant difference was observed. Conclusion - The medial 2/3 of the third rugae and the regional palatal vault dorsal to it is a stable region to register 3D digital models for evaluation of orthodontic tooth movement in adult patients.Dentistry, Oral Surgery & MedicineSCI(E)PubMed5ARTICLE270-791