The validity, reliability, and time requirement of study model analysis using cone-beam computed tomography-generated virtual study models.

OBJECTIVES: To investigate the validity, reliability, and time spent to perform a full orthodontic study model analysis (SMA) on cone-beam computed tomography (CBCT)-generated dental models (Anatomodels) compared with conventional plaster models and a subset of extracted premolars. SETTING AND SAMPLE POPULATION: A retrospective sample of 30 consecutive patient records with fully erupted permanent dentition, good-quality plaster study models, and CBCT scans. Twenty-two extracted premolars were available from eleven of these patients. MATERIALS AND METHODS: Five evaluators participated in the inter-rater reliability study and one evaluator for the intrarater reliability and validity studies. Agreement was assessed by ICC and cross-tabulations, while mean differences were investigated using paired-sample t-tests and repeated-measures anova. RESULTS: For all three modalities studied, intrarater reliability was excellent, inter-rater reliability was moderate to excellent, validity was poor to moderate, and performing SMA on Anatomodels took twice as long as on plaster. CONCLUSIONS: Study model analysis using CBCT-generated study models was reliable but not always valid and required more time to perform when compared with plaster models.

Effect of Employing Different Typodonts When Using E4D Compare for Dental Student Assessment.

The use of computers to aid in instruction and help decrease the subjective component of assessment is steadily increasing. One of the potential barriers to the effective utilization of CAD/CAM technology for assessment purposes is the efficient scanning of the teeth being used for comparison. The purpose of this pilot study was to determine if the use of different typodonts, of the same make and model, has any significant effect on the percent comparison results when using E4D Compare. Tooth #30 was prepared by a faculty member to represent what dental students at Georgia Regents University are taught as the ideal preparation for a full gold crown. Ten typodonts of the same make and model were selected for comparison. Three different examples of students' preparations were scanned and compared to the ideal preparation. Each of the three student preparations was subjected to ten trials (occasions), one for each typodont, at five tolerance levels: 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, and 0.5 mm. The intraclass correlation coefficient (ICC) was used to measure the intrarater agreement among the typodonts at the various tolerance levels. The agreement coefficients (0.971-0.984) indicated very little variability attributable to the use of a different typodont. The high agreement coefficients achieved using different typodonts of the same make and model provide evidence for the interchangeability of typodonts when assessing a student's performance in the preclinical simulation environment.

Avaliaçäo do reembasamento na moldagem com resina acrílica gelada / Evaluated of cold acrylic resin impression

Avaliou-se o reembasamento de moldes obtidos pela técnica de moldagem com resina acrílica gelada comparativamente à uma técnica convencional de moldagem com casquete preenchido com mercaptana. Foi utilizado um dispositivo metálico contendo um troquel para casquetes e um para moldagem. Os troquéis foram metalizados pela eletrodeposiçäo de íons prata no molde. A alteraçäo dimensional dos moldes foi mensurada em microscópio de profundidade, pela discrepância de alinhamento horizontal entre a borda oclusal de um anel de aço que simula uma coroa total e se adapta perfeitamente ao troquel padräo, e a face oclusal de cada troquel reproduzido. As médias das alteraçöes dimensionais e respectivos desvios-padräo, em micrômetros foram: A-) 678,8 (ñ59,2) para Duralay sem reembasamento, 379,9 (ñ72,9) para Duralay com reembasamento e 18,8 (ñ6,2) para o Permlastic. A resina acrílica sem reembasamento apresentou maior alteraçäo dimensional. Troquéis reproduzidos a partir dos moldes de mercaptana apresentaram-se dimensionalmente mais próximos do padräo. O reembasamento demonstrou proporcionar melhora significante na moldagem com a resina acrílica gelada