In this investigation, 63 In-Ceram crowns were placed in 45 patients in both dental school and private practice settings. The restorations were observed for a period of 24 to 44 months, with a mean of 37.6 months. Both anterior and posterior teeth were treated and occlusal conditions were recorded. One crown fractured, yielding a 98.4% success rate. The single fracture was attributed to crown preparation geometry.

Adult↗

PubMedDate not supplied

The in vitro color stability of acrylic resins for provisional restorations.

This study made an in vitro comparative evaluation of the color variation of four types of acrylic resin for provisional fixed prostheses, as determined using computerized spectrophotometry, before and after a 20- and 30-day cycle of immersion in four staining solutions. The four acrylic resins used for provisional fixed restorations were: Cold Pac, Trim, Protemp, and Mixacryl II. Thirty-two specimens for each resin were divided into four subgroups of eight elements, immersed in the four staining solutions (synthetic saliva, synthetic saliva and tea, synthetic saliva and coffee, and synthetic saliva and chlorhexidine in 0.12% water solution), and then placed into four thermostatic baths at 37 degrees C +/- 1 degree C. All specimens were measured for each resin before immersion (baseline). After 20 and 30 days, the specimens were analyzed by computerized spectrophotometry and compared. All data were analyzed with analysis of variance for repeated measures (P < .05). Only the Cold Pac resin was color stable in all staining solutions, while the others showed color changes from the different staining solutions.

Acrylic Resins↗

PubMedDate not supplied

[Effect of ultrasonic scalers, burs and silicone points on the resins for denture bases].

BACKGROUND: Complete dentures in elderly patients often present a large build-up of dental calcolus. In order to avoid this leading to the onset of mycosis or other infections of the oral cavity, all the dental calcolus must be removed during check-ups. METHODS: In order to analyse the consequences of removing the dental calcolus by mechanical means on the resin of the dentures, a polymethylmetacrylate (PMMA) plate was treated with a ultrasonic scaler, with rotating silicone points and with tungsten carbide burrs mounted on a straight hand-grip. The specimens were observed under a light stereomicroscope and their surface was analysed using a surface roughness tester. Observation under the stereomicroscope showed that in all cases the smooth surface of the resin is damaged and modified. RESULTS: The analysis using the surface roughness tester revealed that only very limited quantities of resin are removed whatever the method. Using the lateral edge of the ultrasonic scaler tip and the rotating silicone points mounted on a hand-grip were the techniques that gave the best results, causing the least abrasions. CONCLUSIONS: The results obtained show that after removing the dental calcolus with the instruments tested, the dentures need to be polished in order to prevent the roughness and irregularities caused by the instruments from favouring plaque retention and the consequent reformation of dental calcolus.

Acrylic Resins↗