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Biomedical subjects

P Pera

Publications and source records attributed to P Pera.

At least 55 records · Page 3Linked to original sources
PubMedDate not supplied

Evaluation of occlusal contacts in the dental laboratory: influence of strip thickness and operator experience.

PURPOSE: The purpose of this study was to evaluate the influence of recording strip thickness and of operator-dependent factors on the assessment of contact area on a cast mounted on an articulator. MATERIALS AND METHODS: Thirteen dental students and 13 experts (dentists and dental technicians) performed occlusal maneuvers on casts mounted on an articulator, using recording strips of 8- and 40-micron thickness. Contact area, force, and time of biting relative to each group of operators using each type of paper were compared. RESULTS: Both groups obtained significantly greater contact areas with the thicker strip. Students applied significantly stronger but shorter bitings than experts, but obtained smaller contact areas, particularly with the thinner strip. In operators, the extension of contact markings using the 8-micron strip was closely related to the biting time but not to the occlusion force, while neither time nor force of biting had a significant influence when using the 40-micron strip. CONCLUSION: The assessment of occlusal contact in the dental laboratory was significantly influenced by paper thickness, operator experience, biting force, and time. The 40-micron strip was less influenced by operator experience, strength, and duration of biting.

Analysis of Variance↗
PubMedDate not supplied

Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation.

PURPOSE: The influence of different types of posts and cores on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis and clinical evaluation. MATERIALS AND METHODS: Three extracted natural teeth were replicated in acrylic resin, with roots prepared to receive standardized posts and cores. Using a silicone impression material as a template, various prosthodontic reconstructions were obtained by combining four types of posts and cores (polished and matte-finished gold alloy, all-ceramic, and ceramized metal alloy) and three types of all-ceramic crowns (IPS-Empress 2 surface-colored, IPS-Empress 2 stratified, and In-Ceram). The spectrophotometric analysis was performed in the dark at 25 degrees C. The teeth were backlit with an incandescent lamp at the color temperature of A illuminant and shielded to avoid spurious light entering the spectrophotometer. The transmitted light was analyzed in terms of luminance at four points of the sample surface (cervical, middle, incisal, and proximal). Twelve measurements were performed for the natural teeth, and 144 were performed for the artificial teeth. RESULTS: Natural teeth had the highest luminance. Among all-ceramic crowns, surface-colored IPS-Empress 2 had the highest luminance, and stratified IPS-Empress 2 had the lowest. Regarding posts and cores, the luminance was highest with the all ceramic, lower with the ceramized and the polished gold alloy (which had very similar luminance), and lowest with the matte-finished gold alloy. No significant difference among prosthodontic combinations was detected under clinical observation. CONCLUSION: The surface-colored glass ceramic (IPS-Empress 2) was the most translucent crown. At the standard crown thickness used, there were small, significant spectrophotometric, but not clinical, differences among the combinations tested. These findings show no esthetic contraindications for the use of polished gold alloy posts and cores with all-ceramic crowns.

Acrylic Resins↗