Bodily labializing lateral incisors: 3D analysis using finite element method

Abstract

Aim. Among all tooth types and movements, bodily labializing the upper lateral incisors is a challenging one. The main goal of this study is to introduce and analyze a method to labialize palatally erupted lateral incisors. Materials and methods. Five three dimensional finite element models were designed in SolidWorks 2010 of a segment of maxilla containing the upper left anterior teeth (with the lateral incisor in palatal position), their brackets, their PDLs, the spongy and cortical bone. A segment of 0.016 wire passing through the central incisor and canine brackets (bypassing the lateral incisor bracket) and a designed hook in the lateral incisor bracket (which comprises an inventory approach/design to treat a palatally erupted tooth). The hook and vertical bypassed segment height were 8, 10, 11.5 (stage 1), 9.5 (stage 2) and 9.45 mm (stage 3). Two equal forces (0.15 N each) were applied. Tooth displacements were recorded. Results. A hook length of 8 mm resulted in a tipping movement (apical = −7.78 × 10⁻⁵ mm; incisal = 3.8 × 10⁴ mm). The other two caused root movement. Stage 2 (hook = 9.5 mm) resulted in root movement (−1.4 × 10⁻⁴ mm in incisal; 1.58 × 10⁴ mm in apical area). Hook length = 9.45 produced bodily movement (incisal = 7.1 × 10⁵ mm; apical = 6.9 × 10⁵ mm). Conclusion. A definite length of the hook was shown to produce bodily movement. This definite length of hook in combination with the same length of bypassed wire can be applied to produce bodily movement of the lateral incisor. An intrusive component can also be added.

Key Words::

• orthodontic tooth movement
• bodily movement
• lateral incisor
• finite element method
• tooth levelling and aligning

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.