THE MUCOSAL ATTACHMENT AT DIFFERENT ABUTMENTS - AN EXPERIMENTAL-STUDYIN DOGS

The present experiment was performed to examine if the material used i n the abutment part of an implant system influenced the quality of the mucosal barrier that formed following implant installation. 5 beagle dogs were included in the study. The mandibular premolars and the Ist, 2nd and 3rd maxillary premolars were extracted. Three fixtures of the Branemark System(R) were installed in each mandibular quadrant (a tot al of 6 fixtures per animal). Abutment connection was performed after 3 months of healing. In each dog the following types of abutments were used: 2 ''control abutments'' (c.p. titanium), 2 ''ceramic abutments' ' (highly sintered Al2O3), 1 ''gold abutment'', and 1 ''short titanium abutment''. This ''short titanium abutment'' was provided with an out er structure made of dental porcelain fused to gold. Following abutmen t connection a plaque control program was initiated and maintained for 6 months. The animals were sacrificed and perfused with a fixative. T he mandibles were removed and each implant region was dissected, demin eralized in EDTA and embedded in EPON(R). Semithin sections representi ng the mesial, distal, buccal and lingual aspects of the peri-implant tissues were produced and subjected to histological examination. The f indings from the analysis demonstrated that the material used in the a butment portion of the implant influenced the location and the quality of the attachment that occurred between the periimplant mucosa and th e implant. Abutments made of c.p. titanium or ceramic allowed the form ation of a mucosal attachment which included one epithelial and one co nnective tissue portion that were about 2 mm and 1 - 1.5 mm high, resp ectively. At sites where abutments made of gold alloy or dental porcel ain were used, no proper attachment formed at the abutment level, but the soft tissue margin receded and bone resorption occurred. The abutm ent fixture junction was hereby occasionally exposed and the mucosal b arrier became established to the fixture portion of the implant. It wa s suggested that the observed differences were the result of varying a dhesive properties of the materials studied or by variations in their resistance to corrosion.