RADIOGRAPHICAL AND HISTOLOGICAL CHARACTERISTICS OF SUBMERGED AND NON-SUBMERGED TITANIUM IMPLANTS - AN EXPERIMENTAL-STUDY IN THE LABRADOR DOG

Using 5 Labrador dogs, certain characteristics of the peri-implant tis sues were analyzed after using a 1-step surgical procedure for install ation of Branemark(R) implants. Six titanium implants, 3 in each mandi bular quadrant, were installed in the regions of the right and left fi rst molars and the fourth and third premolars. In the right mandibular quadrant, a traditional 2-step procedure was employed, whilst in the left quadrant, a 1-step procedure was carried out. The animals were mo nitored during a 6-month period. Biopsies of the healed peri-implant m ucosa showed signs of superficial inflammation. The histological analy sis revealed that i) the connective tissue lateral to the junctional e pithelium showed limited accumulations of inflammatory cells (PICT), a nd ii) that at implant sites that had been exposed to the oral cavity for 6 months (1-step implants), an inflammatory cell infiltrate (abutm ent ICT) consistently was present in the tissues facing the abutment-f ixture junction (AFJ). This infiltrate was separated from the bone cre st by a 0.8-mm-wide zone of normal connective tissue. Irrespective of the surgical procedure applied, the radiographic and histometric measu rements disclosed that i) the crestal bone loss was about 2.4 mm, ii) the height of the peri-implant mucosa varied from 3.5 mm to 3.9 mm, ii i) the bone crest was located 1.1-1.5 mm apical of AFJ as well as of t he apical termination of the junctional epithelium (aJE), and iv) a ju nctional epithelium of 2.1-2.4 mm faced the implant surface. In conclu sion, this study demonstrates that, using a dog model, titanium dental implants ad modum Branemark installed according to a 1-step or to a 2 -step surgical procedure will obtain similar soft tissue adaptation an d proper bone anchorage (osseointegration). Further studies are, howev er, required to ascertain the long-term clinical feasibility of the 1- step approach.