Effect of occlusal restoration on stresses around class V restoration interface: A finite-element study.

Background: Causes of failures in class V restorations have always been controversial until now, since the biomechanical aspects of these restorations have been understood. Aims and Objective: This study was aimed to verify the hypothesis that eccentric forces are the cause of cuspal flexure, which lead to excessive stresses at the periphery of a class V restoration, further it identifies the amount of the stress and the flexure increase in the presence of an occlusal restoration using different restorative materials to restore (both cervical and occlusal) along with their comparison with respect to amount of stresses around the cervical restorations. Materials and Methods : The study was done by modeling a mandibular first premolar which was sectioned bucco-lingually, in the NISA, EMRC II finite element software. A 100N eccentric load was applied on the tooth structure and stresses were observed at the peripheries of the class V restoration when it was restored with composite and with glass ionomer cement. The stresses were further analyzed in the presence of occlusal restorations with different materials and configurations. Results: It was seen that the stresses at the gingival wall interface in case of class V glass ionomer cement was more than that for composite. In the presence of an occlusal amalgam restoration, the cuspal flexure was more than that of occlusal composite and the stresses at the class V peripheries were also statistically significant. Conclusion: It was suggested that lower modulus composites can flex with the tooth structure decreasing the bond failure and that the stresses are much lesser when there is absence of an occlusal restoration. Occlusal composite restorations reinforce the tooth structure and reduce the cuspal flexure as compared to silver amalgam.

Mouthguard for relief of repeated clenching stress to cervical restorations during exercises / 대한치과보존학회지

Mouthguards were used to protect boxers from lip lacerations and other soft tissue injuries in the late 19th century. Now they are used various parts of dental treatment, which are sports protective aid, bleaching tray, orthodontic retainer, implant insertion guide tray, splint and so on. Repeated dislodgement of Class V restoration due to habitual clenching stress should be restored with stress control. Mouthguard can be used as stress relief device. This case describes methods that can relieve occlusal force to teeth by using mouthguard. Satisfactory results can be obtained by using mouthguard for retention of repeated dislodgement Class V restorations. If patients suffered from repeated restorations of Class V due to clenching, mouthguard can be used additional device to relieve the occlusal stress in conservative dentistry.

Effects of non-carious cervical lesions and class V restorations on periodontal conditions / 대한치주과학회지

PURPOSE: The non-carious cervical lesion(NCCL) is a loss of tooth structure at the neck of affected teeth that is unrelated to tooth caries. The reported prevalence of NCCL varies from 5% to 85%. Prevalence and severity of lesions have been found to increase with age. They are becoming more significant as people live longer and become more aware of the importance of oral health. The purposes of this study were first, to examine the periodontal conditions associated with NCCL, and second, to investigate the clinical effects of class V restorations of NCCL on periodontal tissues. MATERIALS AND METHODS: The sample size was 982 teeth of 50 subjects(25 male, mean age 52+/-7) who were seen at the Department of Periodontology, Pusan National University Hospital. At the baseline examination, clinical periodontal parameters were measured. After the initial examination, 24 patients who were absent from hypersensitivity were selected. The teeth with NCCL were randomly divided into the test and control groups. The teeth in the test group were restored with flowable resin; the control teeth were not restored. Six months later, the clinical examinations were repeated. The data were analyzed using the SPSS program. RESULTS: The results were as follows: 1) NCCL occurred on 45.8% of examined teeth. The percentage of affected teeth was higher in maxillary and premolar teeth. 2) The shallow saucer type was the most common. 3) Teeth with NCCL had more gingival recession, lower attachment level, and higher incidences of bleeding on probing(BOP) and plaque than NCCL-free teeth. 4) Six months later, gingival recession, attachment level, the percentages of BOP and plaque in the test group were lower than in the control group(p<0.05). CONCLUSION: NCCLs were more found in maxillary teeth, especially in premolar teeth. The results suggest that the restoration of NCCL could affect some periodontal parameters favorably