A HISTOLOGICAL AND HISTOMORPHOMETRICAL EVALUATION OF THE APPLICATION OF SCREW-DESIGNED CALCIUMPHOSPHATE (CA-P)-COATED IMPLANTS IN THE CANCELLOUS MAXILLARY BONE OF THE GOAT

Various studies already have shown that the occurrence of oral implant failure is higher in the maxilla than in the mandible. To learn wheth er Ca-P coatings can improve the success rate of oral implants in the maxilla, three different plasma-sprayed, Ca-P-coated, self-tapping Bra nemark(R) implants were inserted in the trabecular bone of the maxilla . Before the insertion of the implants, the two first upper premolars of 16 goats were bilaterally extracted. Four months later, each animal received four types of implants: three different Ca-P-coated types an d one uncoated. After an endosseous period of 6 months, the implants w ere provided with permucosal abutments. Four months later the animals were killed. At the end of the experiment, it appeared that 10 of the 16 installed noncoated implants had failed while of the 48 Ca-P-coated implants, only 6 had failed. All successful implants were retrieved a nd prepared for histomorphometrical evaluation of the bone and gingiva response. The Ca-P-coated implants showed a significantly greater per centage of bone in contact with the implant surface compared with the uncoated implants. The length of the epithelium was not significantly different for the coated compared to the uncoated implants, but the co nnective tissue was significantly thicker for the noncoated implants t han for the Ca-P-coated implants. Also, measurements revealed that all coatings showed reduction in thickness. On the basis of these finding s, we concluded that the application of Ca-P coatings (1) improves the bone-implant reaction, although all coatings reduced in thickness, an d (2) is of benefit during the healing period in less mineralized trab ecular bone. (C) 1997 John Wiley & Sons, Inc.