Objective To explore the possible influences of intraoral environment on stress relaxation of thermoplastic materials, and compare the stress relaxation rates within different materials.Methods Five kinds of thermoplastic materials were tested in the air under room temperature and in the simulated intraoral environment.The stress relaxation rates were compared.Results The stress relaxation rates of all materials in the simulated intraoral environment were significantly greater than those obtained in the air under room temperature (P＜0.01).Conclusions Stress relaxation of thermoplastic materials could be significantly accelerated in the simulated intraoral environment.

OBJECTIVE:To study the color reappearance effect of metal-ceram restoration and foundry-ceram restoration using Crystaleye spectrophotometer.METHODS:58 metal-ceram restorations and 58 foundry-ceram restorations according to the result of the Crystaleye spectrophotometer were made respectively. The deltaE between restorations and natural teeth as referenced were analyzed. And satisfaction of dentists and patients were evaluated.RESULTS:The deltaE between metal-ceram restorations and natural teeth was 7.13 +/- 0.74. The deltaE between foundry-ceram restorations and teeth was 1.47 +/- 0.84. There were statistical differences between the deltaE (P < 0.01). The satisnatural faction of dentists and patients to the foundry-ceram restorations were higher than to the metal-ceram restorations (P < 0.05).CONCLUSION:Crystaleye spectrophotometer can provide accurate reference for foundry-ceram restoration, but for metal-ceram restoration it is not accurate.

OBJECTIVE To explore the clinical effect of the multidisciplinary treatment combined orthodontics with implant prosthodontics for cases of dentition defect with malocclusion. METHODS Seventeen cases of dentition defect with malocclusion were observed. All the cases accepted the orthodontic treatment in order to establish normal occlusion and achieve adequate space for implants. After that, the missing teeth were replaced by implant-supported denture. The clinical effect was evaluated by clinical examination and radiographic examination. RESULTS Satisfactory esthetic and functional results were achieved for all the cases. The follow-up time ranged from 12 months to 48 months. 76 implants were inserted totally. Two of them were extracted due to peri-implantitis. However, the other 74 implants were stable with an average loading time of 32 months. The cumulative survival rate was 97.4%. CONCLUSION The multidisciplinary approach combined orthodontics with implant prosthodontics was an effective treatment option for cases of dentiton defect with malocclusion.