Influence of adjacent implants with cemented abutments on osseointegration, bone crest remodeling and papillae formation: clinical, radiographic, histomorphometric and nanoindentation analysis in a minipig study

Abstract

Among the many factors that influence the bone resorption around implants and that, consequently, interfere with the formation of interproximal papillae, the kind of union between the implant and prosthetic abutment, interimplantar distance, the distance between the contact point and bone crest and the position of implant in relation to the bone crest level will be investigated in this study by not only the classical methods for the clinical, radiographic, and histomorphometric, but also using a new method of nanoindentation. Firstly the bilateral mandibular premolars of 6 minipigs will be extracted. After eight weeks, four implants will be installed in each hemi-mandible of each animal. Contiguous implants will be separated by 2 or 3 mm (distance interimplantar). Randomly, on one side (right or left) will be installed implants at the bone crest level and on the other, 1.5 mm subcrestally (installation position). Finally, the implants will be left to heal non-submergeously. Cemented- retained abutments will be connected and immediate metallic prostheses will be installed with a fixed distance of 3 mm between the contact point and the top of the bone crest. The variables described above, with emphasis on cementing the abutment, will be evaluated clinically, radiographically and histomorphometrically in terms of papilla formation and crestal bone resorption of the adjacent implants and free ends. Unprecedentedly, the nanoindentation method will be used to compare the hardness and elastic modulus of bone tissue under the influence of the different parameters. (AU)