Korean J Orthod.  2017 May;47(3):158-166. 10.4041/kjod.2017.47.3.158.

Effects of bracket slot size during en-masse retraction of the six maxillary anterior teeth using an induction-heating typodont simulation system

Affiliations
  • 1Department of Orthodontics, School of Dentistry, Kyungpook National University, Daegu, Korea. hmkyung@knu.ac.kr
  • 2Department of Orthodontics, Faculty of Dental Science, Sri Ramachandra University, Chennai, India.

Abstract


OBJECTIVE
To investigate how bracket slot size affects the direction of maxillary anterior tooth movement when en-masse retraction is performed in sliding mechanics using an induction-heating typodont simulation system.
METHODS
An induction-heating typodont simulation system was designed based on the Calorific Machine system. The typodont included metal anterior and resin posterior teeth embedded in a sticky wax arch. Three bracket slot groups (0.018, 0.020, and 0.022 inch [in]) were tested. A retraction force of 250 g was applied in the posterior-superior direction.
RESULTS
In the anteroposterior direction, the cusp tip of the canine in the 0.020-in slot group moved more distally than in the 0.018-in slot group. In the vertical direction, all six anterior teeth were intruded in the 0.018-in slot group and extruded in the 0.020- and 0.022-in slot groups. The lateral incisor was significantly extruded in the 0.020- and 0.022-in slot groups. Significant differences in the crown linguoversion were found between the 0.018- and 0.020-in slot groups and 0.018- and 0.022-in slot groups for the central incisor and between the 0.018- and 0.022-in slot groups and 0.020- and 0.022-in slot groups for the canine. In the 0.018-in slot group, all anterior teeth showed crown mesial angulation. Significant differences were found between the 0.018- and 0.022-in slot groups for the lateral incisor and between the 0.018- and 0.020-in slot groups and 0.018- and 0.022-in slot groups for the canine.
CONCLUSIONS
Use of 0.018-in slot brackets was effective for preventing extrusion and crown linguoversion of anterior teeth in sliding mechanics.

Keyword

Tooth movement; Appliances; Heat induction typodont; Bracket slot size
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