Accuracy of four types of rubber impression materials compared with time of pour and a repeat pour of models

The accuracy of four types of elastomeric impression materials was studied as a function of model location, time of pouring, and repetition of pouring. There was little change in dimension among abutment preparations for all materials, for all times of pour, and with a repeat pouring. It appears that measurements between posts are not sensitive to detecting differences between materials and that other dimensions should be examined to discern where differences might lie. The diameter of the stone post was larger than the standard for the AS and PS materials and was unchanged or smaller than the standard for the CS and the PE. The vertical dimensions of stone posts were, in general, shorter than the standard for all materials, with the AS demonstrating the smallest change. The AS and CS products demonstrated the best recovery from undercuts and the least change in dimensions between an initial and second pour of an impression. The AS and PE were the least affected with delays of 1, 4, and 24 hours in pouring the impression.     

Comparison of fresh autogenous and freeze-dried allogenic skin for mandibular vestibuloplasty

This study compared the ability of fresh autogenous and freeze-dried allogenic split-thickness skin grafts to maintain vestibular depth following vestibuloplasty. Both graft systems resulted in covering of the alveolar ridge by firmly attached tissue, which would be expected to enhance prosthetic stability. The appearance of the fresh autogenous grafts was consistent with that of mature skin grafts, whereas the freeze-dried grafts had the appearance of alveolar mucosa. Vestibular depth stabilized at six weeks with both graft systems, and at six months there was no significant difference (P less than 0.05) between the freeze-dried and fresh grafts with respect to their ability to maintain vestibular depth.     

The effect of chronic red cell mass depletion on the healing of bone grafts

The purpose of this study was to determine whether a marked decrease in red cell mass with a normal blood volume (normovolemic anemia) would compromise osseous repair in experimental mandibular bone grafts. In adult male dogs, osseous defects in the mandibular body were restored with combined allogeneic and autologous bone grafts. In the experimental group, the red cell mass was depleted by a mean 55% of the baseline value and the resulting anemia maintained for eight weeks by serial phlebotomies. In the control group phlebotomy was not performed. Osseous repair was evaluated by quantitative sequential radionuclide imaging, subjective and quantitative determinations of graft stability, and histologic examination. Results demonstrated no significant difference in bone graft repairs between the anemic and control animals by any of the evaluation methods over the eight-week period of study (P greater than 0.05).     

Effects of 3 months frequent consumption of hydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol and xylitol on human dental plaque.

Lozenges containing hydrogenated starch hydrolysate (Lycasin), maltitol, sorbitol or xylitol were consumed 4 times daily during 3 months by 4 groups of persons (in all 85 subjects). In the maltitol-, sorbitol- and xylitol-group the plque wet weights were of the same magnitude before and after the test period. In the Lycasin-group, a higher value was found after than before the 3-month period (p less than 0.01). The acid production in suspensions of dental plaque material from Lycasin, maltitol and sorbitol expressed as per cent of that from glucose was approximately the same before and after the test period. From xylitol no acid production could be demonstrated either before or after the 3-month period. There were no statistically significant differences between the plaque pH-changes induced by rinsing with 50% solutions of Lycasin, maltitol, sorbitol or xylitol before and after the test period. However, there was a tendency (p less than 0.05) towards lower pH-values induced by the maltitrol and sorbitol rinse after the 3-month period compared with before. No difference in the relative numbers of facultative anaerobic streptococci. Streptococcus mutans or facultative anaerobic lactobacilli before and after the test period was found.