Abstract: Objective: To investigate the restorative effect of coralline hydroxyapatite and beta-tricalcium phosphate on the defect healing around implants. Methods: All mandibular premolars and 1st molars were extracted bilaterally in six Beagle dogs. After a healing period of three-month, four experimental canals were prepared on each side of the mandible. The margin of the canal was further drilled to create the 1-1.25mm circumferential and 5mm deep bone defect around the coronal portion. Then, four implants were inserted in extraction sites on each side. The standardized bone defects were filled with blood clot, CHA or with β-TCP，respectively. All implants were non-submerged. Each two dogs were sacrificed at weeks 4, 12 and 16 following implant placement, and the specimens were prepared and stained with trinitrophenol fuchsin for histological and histomorphometric analyses to acquire the data about the distance between the most coronal level of bone-to-implant contact and the bottom of the surgically created bone defect(B-D), and the data about the bone-to-implant contact (BIC%) within the defect area. Values for newly formed bone area percentage (NFB%) and remaining bone substitutes percentage (RBS%) were additionally calculated for all biomaterial-grafted samples utilizing the Image-Pro Plus 6.0 software. Results: No implant was loosen or lost after installation, the peri-implant soft tissue was indicated no inflammation. At weeks 4 and 12, the differences in B-D and BIC% were not statistically significant between three treatment groups(P>0.05); the B-D, BIC% values for β-TCP –grafted group were significantly higher than for CHA-grafted group at week 16(P<0.05). There were statistically significant differences in RBS% within bone defect area between CHA-grafted and β-TCP –grafted groups at week 12、16，and the NFB% value of β-TCP –grafted group was shown significantly greater than that of CHA-grafted group(P<0.05).Conclusion: Bone regeneration within defects surrounding the implant could be accelerated with the use of β-TCP than CHA, it was suggested that the application of β-TCP was one more predictable treatment with respect to restoring bone defects around implants.

Key words: Coralline hydroxyapatite, Beta-tricalcium phosphate, Dental implant, Bone defect