Patient-specific finite element analysis of viscoelastic masticatory mucosa

Abstract

The purpose of this study was to analyze the stress and strain inside of the oral mucosa in partially-edentulous patients. The patient-specific finite element models of the mucosa and the bone were constructed using the CT images and in-vivo surface measurement during a continuous load. The mean initial shear modulus of 8.3 × 10–5 (GPa) and the mean relaxation time of 503 (s) were determined as the viscoelastic properties of the mucosa. The increase of the highest maximum compressive strain during the continuous loading was observed in all the patients, however; the intensity of strain was not in accordance with the thickness of the mucosa. It is suggested that the variations of the morphology and the initial modulus of the mucosa should be considered in the mathematical approaches to detect the mechanical responses of the oral mucosa.

Determination of oral mucosal Poisson’s ratio and coefficient of friction fromin-vivocontact pressure measurements

“…While FEA provides a feasible approach to modelling load transfer, it is difficult to assign realistic mucosa properties (Inoue et al 1985). Although the previous studies (Sawada et al 2011;Wakabayashi and Suzuki 2013) attempted to derive the nonlinear moduli of mucosa via the same approach as hard tissues, data regarding its volumetric deformation have not been identified specifically. More importantly, the effect of the apparent Poisson's ratio has been largely disparaged due to lack of data (Inoue et al 1985).…”

“…In fact, apparent Poisson's ratio (n) of mucosa has not been considered as a critical factor in some literature (Inoue et al 1985). Previous FE studies have assumed a rather broad range of possible values, from 0.30 to 0.49 (Lacoste-Ferré et al 2011;Sawada et al 2011;Kanbara et al 2012;Ż mudzki et al 2012a, 2012bWakabayashi and Suzuki 2013). From a biomechanics perspective, the effect of apparent Poisson's ratio has not been adequately addressed thus far.…”

“…Significant interest has arisen and extensive studies have been undertaken regarding the biomechanical responses of mucosa under denture treatment. Both instant nonlinear elastic responses (Scapino 1967;Kishi 1972;Kydd et al 1974;Kanbara et al 2012) and time-dependent viscous responses (Inoue et al 1985;Lacoste-Ferré et al 2011;Sawada et al 2011;Wakabayashi and Suzuki 2013) of the mucosa have been examined via experimental and numerical approaches. This highly vascularized tissue consists of considerable amount of interstitial fluids, and the substantial fluidic exchange occurs with surrounding tissues under compression (Scapino 1967;Kydd and Daly 1982).…”

“…(a) Masks segmented for individual components from two individual CT scans, patient jaw and denture, presenting mucosa (transparent maroon), cortical bone (transparent yellow), cancellous bone (opaque orange), teeth (opaque grey), denture base (transparent cyan), frame (opaque blue), and artificial crowns (opaque red); (b) solidified model with NURBS representation after visual insertion of the removable partial denture; (c) finite element models meshed in ABAQUS 6.9.2 and (d) loading conditions (orange: native teeth; blue: artificial crowns) and boundary conditions (cyan triangles) assigned to the model.Computer Methods in Biomechanics and BiomedicalEngineering 3 range of n (from 0.30 to 0.49) has been assumed in the literature(Lacoste-Ferré et al 2011;Sawada et al 2011;Kanbara et al 2012;Ż mudzki et al 2012a, 2012bWakabayashi and Suzuki 2013). Soft tissue is often considered to be nearly incompressible by taking a very high Poisson's ratio of 0.499.…”

Relevance of Tongue Force on Mandibular Denture Stabilization during Mastication

“…The displacements were significantly higher than allowable tissue deformation; therefore, they are a result of denture movement . Nonlinear material characteristics of soft tissue may influence the displacement by up to 20% . For this reason, the linear elastic model provides a good approximation of realistic denture behavior.…”