Mechanic and photoelastic evatuation of 2.0mm locking plate system for bridging segmental mandibular defects

Author(s)

Patrício José de Oliveira Neto

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2012-07-12

Examining board members

Luciana Asprino; Cassio Edvard Sverzut; Anibal Henrique Barbosa Luna; Henrique Clasen Scarparo; Saulo Ellery Santos

• Advisor: Luciana Asprino

Abstract

Currently mandibular continuity defects are conventionally treated with 2.4mm titanium reconstruction plates. However, the reconstruction systems have become progressively slimmer and more malleable and the 2.0mm locking reconstruction plate system has been introduced as the next generation system to improve on current reconstruction plate designs. The purpose of the present investigation was comparatively evaluate the mechanical behaviour and the stress distribution promoted by 2.4mm reconstruction plate system and 2.0mm locking reconstruction plate system in mandibular continuity defects, with or without block grafts. Twenty polyurethane mandibles (Synbone®) were underwent to a 5-cm mandibular body ressection and equally divided among 4 groups. In groups 1 and 3, the mandibles were bridged with a 2.0mm locking reconstruction plate system and with a 2.4mm reconstruction plate system respectively. In groups 2 and 4 the mandibles were fixated with a 2.0mm locking and 2.4mm reconstruction plates, being associated with block grafts. The mandibles from each group were subjected to contralateral molar load until 5-mm displacement, and the values were recorded. Mandibular photoelastic models simulating the type of mandibular defect and plate fixation with or without block grafts were subjected to the same contralateral molar load. Statistical analysis showed that the 2.4 mm plate showed statistically superior mechanical strength to the locking plate 2.0 mm, regardless of the presence or absence of graft, probably due to the greater plate thickness and diameter of the screws. In relationship to the graft, it was observed for both types of fixation systems that its presence did not increase the mechanical strength of the plate - graft - mandible set when compared to the without graft situation. However, the photoelastic analysis found that the combination of graft resulted in a lower stress concentration around screw and plate, with a more balanced distribution of tension, which may favor the use of locking plates 2.0 mm when associated with immediate bone reconstruction. It can be concluded that: the 2.0mm locking reconstruction plate system had an unsatisfactory mechanical strength for reconstruction of mandibular continuity defects; the association of bone graft provided a better stress distribution, but did not increase the mechanical strength of the systems evaluated in the reconstruction of mandibular continuity defects (AU)

• FAPESP's process: 10/19344-3 - MECHANICAL AND PHOTOELASTIC EVALUATION OF 2.0-mm LOCKING RECONSTRUCTION PLATE FOR SEGMENTAL RESECTION OF THE MANDIBLE
• Grantee: Patrício José de Oliveira Neto
• Support Opportunities: Scholarships in Brazil - Doctorate