To evaluate the sealing potential of self-designed root canal filling material made of calcium phosphate cement (alpha-TCP/TTCP, CPC), the apices of root canals of six adult dogs were purposely perforated and enlarged up to the No 40 instrument. Then CPC was used to fill the root canal. Mean while either calcium hydroxide (Ca(OH)2) paste or hydroxyapatite (HA) paste was used as control. The animals were killed at 4, 12, 20 weeks postoperatively. The different materials about ways of apical closure, restoration periapocal tissues and adaptability to the dentinal surface were observed by histomorphology and scanning electron microscopic. This study revealed that CPC had excellent biocompatibility and adaptability to the dentinal wall. Its osteoconduction can promote the formation of calcific barriers and healing of periapical tissue. The apex can be closed completely. Compared with the control pastes it has advantages of ease of manipulation and better sealing capability. The results showed that CPC could be used as a root canal filling material for pupless teeth with open apex and destructive periapical tissue.
Animals ; Calcium Phosphates ; pharmacology ; Dogs ; Root Canal Filling Materials ; pharmacology ; Root Canal Therapy

To establish an experimental model of osteoblasts to easily cause calcification of bone matrix in vitro, we took cranium of a newborn rabbit out under an aseptic condition, removed the connective tissue of the bony suture, and cut the cranium freely into the fragments of not more than 1 mm2. The we isolated and cultured the osteoblasts using tissue explant method. We observed growth status of primary osteoblasts and subcultured osteoblasts using inverted microscope. Then we conducted enzyme staining and alizarin red staining for the third generation of osteoblasts to detect the alkaline phosphatase (ALP) expression and calcified nodules. The result showed that there were calcified nodules or calcification formed after the primary osteoblasts climbing out from the bone for 1 week, and each generation of osteoblasts had the similar calcification with the primary osteoblasts, and there was an increase in calcified nodules after the continuous culture. There was a strong expression of ALP in the plasma membrane of osteoblasts. The calcified nodules were red with alizarin red staining. It is well concluded that osteoblasts isolated with this method easily cause calcification, and can be used as a new experimental model.
Alkaline Phosphatase ; metabolism ; Animals ; Animals, Newborn ; Cell Separation ; methods ; Osteoblasts ; cytology ; Primary Cell Culture ; methods ; Rabbits ; Skull ; cytology