The influence of composite resin restoration on the stress distribution of notch shaped noncarious cervical lesion; A three dimensional finite element analysis study / 대한치과보존학회지

The purpose of this study was to investigate the effects of composite resin restorations on the stress distribution of notch shaped noncarious cervical lesion using three-dimensional (3D) finite element analysis (FEA). Extracted maxillary second premolar was scanned serially with Micro-CT (SkyScan1072; SkyScan, Aartselaar, Belgium). The 3D images were processed by 3D-DOCTOR (Able Software Co., Lexington, MA, USA). ANSYS (Swanson Analysis Systems, Inc., Houston, USA) was used to mesh and analyze 3D FE model. Notch shaped cavity was filled with hybrid or flowable resin and each restoration was simulated with adhesive layer thickness (40 microM). A static load of 500 N was applied on a point load condition at buccal cusp (loading A) and palatal cusp (loading B). The principal stresses in the lesion apex (internal line angle of cavity) and middle vertical wall were analyzed using ANSYS. The results were as follows 1. Under loading A, compressive stress is created in the unrestored and restored cavity. Under loading B, tensile stress is created. And the peak stress concentration is seen at near mesial corner of the cavity under each load condition. 2. Compared to the unrestored cavity, the principal stresses at the cemeto-enamel junction (CEJ) and internal line angle of the cavity were more reduced in the restored cavity on both load conditions. 3. In teeth restored with hybrid composite, the principal stresses at the CEJ and internal line angle of the cavity were more reduced than flowable resin.

Effects of occlusal load on the cervical stress distribution: A three-dimensional finite element study / 대한치과보존학회지

The objective of this study was to investigate the effects of various occlusal loads on the stress distribution of the buccal cervical region of a normal maxillary second premolar, using a three dimensional finite element analysis (3D FEA). After 3D FE modeling of maxillary second premolar, a static load of 500N of three load cases was applied. Stress analysis was performed using ANSYS (Swanson Analysis Systems, Inc., Houston, USA). The maximum principal stresses and minimum principal stresses were sampled at thirteen nodal points in the buccal cervical enamel for each four horizontal planes, 1.0 mm above CEJ, 0.5 mm above CEJ, CEJ, 0.5 mm under CEJ. The results were as follows 1. The peak stress was seen at the cervical enamel surface of the mesiobuccal line angle area, asymmetrically. 2. The values of compressive stresses were within the range of the failure stress of enamel. But the values of tensile stresses exceeded the range of the failure stress of enamel. 3. The tensile stresses from the perpendicular load at the buccal incline of palatal cusp may be shown to be the primary etiological factors of the NCCLs.

Effects of occlusal load on the stress distribution of four cavity configurations of noncarious cervical lesions: a three-dimensional finite element analysis study / 대한치과보존학회지

The objective of this study was to investigate the effect of excessive occlusal loading on stress distribution on four type of cervical lesion, using a three dimensional finite element analysis (3D FEA). The extracted maxillary second premolar was scanned serially with Micro-CT. The 3D images were processed by 3D-DOCTOR. ANSYS was used to mesh and analyze 3D FE model. Four different lesion configurations representative of the various types observed clinically for teeth were studied. A static point load of 500N was applied to the buccal and lingual cusp (Load A and B). The principal stresses in lesion apex, and vertical sectioned margin of cervical wall were analyzed. The results were as follows 1. The patterns of stress distribution were similar but the magnitude was different in four types of lesion. 2. The peak stress was observed at mesial corner and also stresses concentrated at lesion apex. 3. The compressive stress under load A and the tensile stress under load B were dominant stress. 4. Under the load, lesion can be increased and harmful to tooth structure unless restored.