Nonlinear visco-elastic finite element analysis of porcelain veneers: a submodelling approach to strain and stress distributions in adhesive and resin cement.
OBJECTIVE
To assess under load the biomechanical behavior of the cementing system of feldspathic vs alumina porcelain veneers.


METHODS
A 3D model of a maxillary central incisor, the periodontal ligament (PDL) and the alveolar bone was generated. Incisors restored with alumina and feldspathic porcelain veneers were compared to a natural sound tooth. Enamel, cementum, cancellous and cortical bone were considered isotropic elastic materials; conversely, dentin was designated as orthotropic. The nonlinear visco-elatic behavior of the PDL was considered. The adhesive layers were modelled using spring elements. A 50-N load at a 60-degree angle to the tooth's longitudinal axis was applied and validated. Stress concentration in the interfacial volumes of the main models was identified and submodelled in a new environment.


RESULTS
Regarding tooth structure, strain concentrations were observed in the root dentin below the CEJ. As to the cement layer, tensile stresses concentrated in the palatal margin of the adhesive complex.


CONCLUSIONS
Despite the effects on tooth deformation, the rigidity of the veneer did not affect the stress distributions in the cement layer or in the adhesive layers. In both cases, the palatal and cervical margins seemed to be the most stressed areas.
Department of Oral Sciences, Second University of Naples, Naples, Italy.
Letizia
L
Perillo
Roberto
R
Sorrentino
Davide
D
Apicella
Alessandro
A
Quaranta
Enrico
E
Gherlone
Fernando
F
Zarone
Marco
M
Ferrari
Raffaella
R
Aversa
Antonio
A
Apicella
D000537:Aluminum Oxide / Q000737:chemistry; D000538:Aluminum Silicates / Q000737:chemistry; D000539:Alveolar Process / Q000033:anatomy & histology; D001696:Biomechanical Phenomena; D001732:Bite Force; D003188:Composite Resins / Q000737:chemistry; D003198:Computer Simulation; D003739:Dental Cementum / Q000033:anatomy & histology; D003743:Dental Enamel / Q000033:anatomy & histology; D003776:Dental Porcelain / Q000737:chemistry*; D017267:Dental Prosthesis Design; D003801:Dental Veneers; D003804:Dentin / Q000033:anatomy & histology; D055119:Elastic Modulus; D004548:Elasticity; D020342:Finite Element Analysis; D005899:Glass Ionomer Cements / Q000737:chemistry; D006801:Humans; D021621:Imaging, Three-Dimensional; D007180:Incisor / Q000033:anatomy & histology; D008422:Materials Testing; D008954:Models, Biological; D017711:Nonlinear Dynamics; D010513:Periodontal Ligament / Q000033:anatomy & histology; D017680:Potassium Compounds / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013314:Stress, Mechanical; D013499:Surface Properties; D019237:Tooth Cervix / Q000033:anatomy & histology; D014092:Tooth Root / Q000033:anatomy & histology; D014783:Viscosity
D000538:Aluminum Silicates; D003188:Composite Resins; D005899:Glass Ionomer Cements; D017680:Potassium Compounds; D019279:Resin Cements; C084550:Vitremer; D003776:Dental Porcelain; C016447:feldspar; D000537:Aluminum Oxide