Initial Stresses induced in Permanent Maxillary First Molar in Mixed Dentition under Normal Masticatory Forces: A Finite Element Study.

Objective: The cross-arch space maintainers are used to prevent mesio-distal movement of teeth under physiologic forces, contrary to adult orthodontics where these are used as anchorage against orthodontic forces. Stresses in periodontal ligaments (PDL) are supposed to be different in pediatric dentistry and need to be studied. This study aimed to create mathematical model and calculated the initial stresses generated in the PDL and the behavior of movement in developing permanent maxillary first molar under masticatory forces using 3D finite element analyses (FEA).

Study Design: Data acquisition, image processing, geometric modeling followed by FE analyses was done under vertical load of 70N. The generated stress and tooth displacement were observed with or without primary second molar, mesial to permanent maxillary first molar.

Results: Masticatory forces resulted in insignificant initial PDL stresses and mesial displacement of permanent maxillary first molar in the intact arch. In the case of missing primary second molar, maximum stresses were on the palatal root and the tooth showed greater mesial displacement with mesio-palatal rotation.

Conclusions: Any space maintainer preventing mesio-palatal rotation of permanent maxillary first molar, under physiologic masticatory loadings, may be inserted in case of multiple tooth loss.