ABSTRACT
Objective@#To study the blocking effect and abrasion resistance of hydroxyapatite (HA) with different particle sizes and morphologyies on dentinal tubules from the qualitative and quantitative aspects. @*Methods @# Dentin discs were etched and divided into 4 groups randomly: 20 nm HA group; 30 nm HA group; 12 μm HA group; control group (without any experimental treatment). Each group was brushed with correspondent materials for 7 days. Then, the dentin disk was divided into two parts, the one was detected by the scanning electron microscopy (SEM); the other was observed by SEM after toothbrush abrasion test. The Image-Pro Plus 6.0 image analysis software was used to calculate the plugging rate of dentinal tubules. @*Results @#SEM showed that the blockage is granular, the plugging rate of the dentinal tubules were about 82% to 96%. 30 nm HA group (short rod) range the first in the average plugging rate, followed by the 20 nm HA group (needles) and 12 μm HA group (spherical). After mechanical brushing for 7 days, SEM images showed that deposited layer in each group was smooth and compact, and more than 63% of the tubules still had been blocked. @* Conclusion @#HA with different particle sizes and morphologies had good plugging effect and abrasion resistance on dentine tubules. The blocking effect of HA was affected not only by particle size but also by the morphology.
ABSTRACT
Objective @#To establish an animal model that clinically conforms to the characteristics of severe alveolar ridge atrophy. @*Methods @#Beagle dogs were used as experimental subjects. Bilateral fourth premolars and first molars in mandible were extracted. A horizontal groove was made on alveolar ridge which was 8 mm from the cemento-enamal junction of mandible third premolar and second molar. Rongeur was used to remove the alveolar bone above this groove and bone chisel was used to level the bone-free area. A box-shaped defect cavity of the size 25 mm × 8 mm was formed with sterile silicone prosthesis implanted. After careful suture we waited for the subjects to heal naturally. Eight weeks after operation, CBCT examination was performed.@*Results @#Eight weeks after bone remodeling the top of alveolar ridge of operation area appeared to be a circular arc. The average distance from the bottom of the ridge to inferior alveolar nerve canal was 2.5 mm. @*Conclusion @#This study successfully established the Beagle dog animal model for severe alveolar ridge atrophy and laid the foundation for experiments on vertical bone augmentation.