In this study, we observed the long-term stabiliy of adhesion and the influence of 4-META/MMA-TBB resin on bone. The cranial bone surfaces of rats were surgically exposed and treated with 10% citric acid and 3% ferric chloride agueous solution, and then washed and dried. 4-META/MMA-TBB resin was applied, and the bone surface was observed under LM, SEM, and TEM after 1 day, and 6, 9, and 12 months. The resin was directly adhered to bone via a hybrid layer, and few inflammatory cells were found. The osteocytes showed atrophy and they were absent in the outer layer of the bone which was surgically exposed, pretreated, and dried. After 12 months, there was no invasion of connective tissue in the interface between resin and bone. Bone to which resin was applied was continuous with the surrounding bone and was replaced slowly with newly-formed bone. It is concluded that the adhesion between 4-META/MMA-TBB resin and bone and biocompatibility showed long-term stability.

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By employing instruments that measure setting expansions using a laser displacement sensor and trial programs made by Visual Basic, the effect of molds used in the measurement of setting expansions of the dental stone were investigated. Then, utilizing the vertically splittable mold, the setting behavior of three kinds of dental gypsum and two investments was investigated. At the setting time or the time which the dimensional change reached a minimum, greater shrinkage was observed in the vertically splittable mold and glass tube than that in the JIS mold. There was no significant difference in the values when minimum dimensional changes were subtracted from those after 120 minutes. From these results, the splittable mold was used to measure the dimensional changes of three kinds of dental gypsum and two investments. All materials shrank at the setting time or at the time of reaching the minimum value. High-level shrinkage was observed in the dental stone and cristobalite investment after 120 minutes, and marked expansion was noted only in the phosphate-bonded investment. The values of dimensional change after 120 minutes subtracted from the minimum value generated values similar to those observed in the JIS methods for all materials in this study. Therefore, by employing these values, the accurate analysis of the behavior of dimensional change became possible. From these results, the measurement method utilizing the lazer displacement meter and measurement program facilitated monitoring of the setting procedure, and measurement of the dimensional change with high-level accuracy.

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