Three-dimensional Finite Element Analysis of the Biomechanical Strength of the Mandible After Marginal Resection

Ueda, Nobuhiro

Three-dimensional Finite Element Analysis of the Biomechanical Strength of the Mandible After Marginal Resection

Nobuhiro Ueda DDS, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Yuichiro Imai DDS,PhD, Department of Oral and Maxillofacial Surgery, Nara Medical University, Kashihara, Japan

Tsutomu Sugiura DDS, PhD, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Kazuhiro Murakami DDS, PhD, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Nobuhiro Yamakawa DSS, DMSc, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Kumiko Aoki DDS, PhD, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Satoshi Horita DDS, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Kazuhiko Yamamoto DDS, PhD, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Tadaaki Kirita DDS, DMSc, Department of Oral and Maxillofacial Surgery, Nara Medical University, Nara-Kashihara, Japan

Background: Marginal resection of the mandible has been performed in cases of lower gingival carcinoma. However, pathologic fractures may occur as the result of the decrease in mandibular body height. The mandibular strength after marginal resection depends on the residual height of the mandible and the resection form.

Purpose: The purpose of the present study is to analyze the stress in the mandible after marginal resection in terms of the residual height and resection form using a finite element(FE) analysis.

Materials and methods: A three dimensional FE model of the human mandible was constructed by use of MECHANICAL FINDER^R from the CT data of a 41-year-old man. Models of marginal resection were created by resecting the upper part of the right mandibular body at the area between the first premolar and the second molar. A total of 30 models with 5 different residual heights of the mandibular body of 5, 7.5, 10, 12.5 and 15mm and with a curve given at the corners of the resected bottom with 6 different radius of 0(right angle),3,6,9,12 and 15mm was created. The bilateral condyles were completely constrained. The proportion of the magnitude of the forces of masseter, temporal and medial pterygoid muscles was defined as previously reported. The bite force of 478.1 N was applied at the left first molar as a point load perpendicular to the occlusal plane. Linear 3 dimensional FE analyses were performed. von Mises stress was calculated to evaluate mechanical stress in the mandible.

Result:von Mises stresses were concentrated at the posterior buccal resection corner of the mandible in all models. The maximum von Mises stress was 108 MPa in the model with the residual height of 5mm with the right angle corner (the curve with 0mm radius). The relative stress values compared with that of this model were 80%, 63%, 58% and 54% in the models of the residual height of 7.5, 10, 12.5 and 15mm, respectively, and were 90%, 81%, 74%, 67% and 61% in the models of the radius at the corner of 3, 6, 9, 12 and 15mm, respectively.

References:

1.　Murakami K, Sugiura T, Yamamoto K, Kawakami M, Kang YB, Tsutsumi S, Kirita T: Biomechanical analysis of the strength of the mandible after marginal resection. J Oral Maxillofac Surg 69:1798, 2011

2.　Ertem SY, Uckan S, Ozden UA: The comparison of angular and curvilinear marginal mandibulectomy on force distribution with three dimensional finite element analysis. J Craniomaxillofac Surg 41:e54, 2013