Immediate transmucosal implant placement in molar extraction sites: a 12-month prospective multicenter cohort study.

AIM: To assess the clinical and radiographic outcomes of immediate transmucosal placement of implants into molar extraction sockets. STUDY DESIGN: Twelve-month multicenter prospective cohort study. MATERIAL AND METHODS: Following molar extraction, tapered implants with an endosseous diameter of 4.8 mm and a shoulder diameter of 6.5 mm were immediately placed into the sockets. Molars with evidence of acute periapical pathology were excluded. After implant placement and achievement of primary stability, flaps were repositioned and sutured allowing a non-submerged, transmucosal healing. Peri-implant marginal defects were treated according to the principles of guided bone regeneration (GBR) by means of deproteinized bovine bone mineral particles in conjunction with a bioresrobable collagen membrane. Standardized radiographs were obtained at baseline and 12 months thereafter. Changes in depth and width of the distance from the implant shoulder (IS) and from the alveolar crest (AC) to the bottom of the defect (BD) were assessed. RESULTS: Eighty-two patients (42 males and 40 females) were enrolled and followed for 12 months. They contributed with 82 tapered implants. Extraction sites displayed sufficient residual bone volume to allow primary stability of all implants. Sixty-four percent of the implants were placed in the areas of 36 and 46. GBR was used in conjunction with the placement of all implants. No post-surgical complications were observed. All implants healed uneventfully yielding a survival rate of 100% and healthy soft tissue conditions after 12 months. Radiographically, statistically significant changes (P<0.0001) in mesial and distal crestal bone levels were observed from baseline to the 12-month follow-up. CONCLUSIONS: The findings of this 12-month prospective cohort study showed that immediate transmucosal implant placement represented a predictable treatment option for the replacement of mandibular and maxillary molars lost due to reasons other than periodontitis including vertical root fractures, endodontic failures and caries.

Brånemark System Wide Platform implants for single molar replacement: clinical evaluation of prospective and retrospective materials.

BACKGROUND: The use of oral implants for single tooth replacement has become a predictable treatment modality. As single tooth loss is most common in posterior areas of the jaws, the use of the protocol is of specific interest in those regions. New implant designs aimed at this purpose have also been introduced. PURPOSE: The aim of the study was to present the outcomes for wide diameter implant treatment when being used in posterior areas of the jaws. MATERIALS AND METHODS: This paper presents the 3-year results of a prospective multicenter study (three clinics; n = 38 implants) and the 1-year results from a retrospective multicenter study (two clinics; n = 20 implants) on wide diameter implants for single molar replacement. Based on the hypothesis that dense bone in posterior mandibles would benefit from careful surgery and longer remodeling time, the influences of surgical technique and healing time on implant success and bone resorption were particularly addressed. RESULTS: The outcome demonstrated a good predictability for Brånemark System Wide Platform implants, at least short term, when used as single molar support (prospective group cumulative success rate [CSR] = 92% after 3 years; retrospective group CSR = 95% after 1 year). The increased mechanical strength of the wide platform implant/abutment complex also turned out to be important for mechanical stability. CONCLUSIONS: The study indicated that it was important to carefully perform surgery in posterior mandibles in order to preserve and optimally use the existing dense bone. It was suggested that from bone healing and remodeling aspects, posterior mandibles may be more demanding to handle than corresponding areas of maxillae.

Composition of plaque-associated lesions in the gingiva and the peri-implant mucosa in partially edentulous subjects.

The purpose of the present investigation was to study characteristics of the plaque associated lesions in the gingiva and the adjacent periimplant mucosa sampled from the same subjects. 20 partially edentulous patients (12 female and 8 male, 30-60 years of age) volunteered to participate in the study. They had all been treated for moderate to advanced periodontal disease. Edentulous regions had been restored with implants. The restorative therapy had been completed 6-24 months prior to soft tissue biopsy. Samples of gingival tissue (GM) and periimplant mucosa (PIM) from an "interproximal surface" of one tooth site and one implant site of the same jaw were harvested. One portion of the biopsy was embedded in EPON, stained in PAS and toluidine blue and used for histometric and morphometric analyses. The 2nd portion of the biopsy was snap frozen in liquid nitrogen. 15 sections, about 5 microns thick, were prepared in a cryostat and used for immune histochemical staining. The analysis of the sections included determination of the size of the lesions as well as assessments of various cells and cell markers. In all samples of both PIM and GM discrete infiltrates of inflammatory cells (ICT) were found in the connective tissue lateral to the junctional epithelium. The ICT of PIM occupied on the average 0.17 +/- 0.14 mm2 of the soft tissue, while the corresponding lesion in GM occupied an area that was 0.25 mm2 +/- 0.21 mm2 large. The density of CD19 positive cells was 7 times higher in GM than in PIM (3.7 versus 0.5) while the densities of CD3 positive cells were 7.5 (GM) and 4.7 (PM) respectively. The density of PMN elastase positive cells was about 3 times higher in GM than in PIM (3.7 versus 1.2). Care must be exercised when these differences are interpreted. It is possible that a prolonged exposure of the implant site to the oral environment may induce both qualitative and quantitative changes of the infiltrate in PIM.

Some characteristics of the ridge mucosa before and after implant installation. A prospective study in humans.

The aim of the present investigation was to study some tissue characteristics of the ridge mucosa before and after implant installation. 9 partially edentulous patients were included in the study. At the time of fixture installation, 1 recipient site in each patient was selected for soft tissue biopsy. Abutment connection and restorative therapy were performed after 3-6 months. When the implants had been in function for about 6 months, a soft tissue sample was obtained from the keratinized peri-implant mucosa at the 1 implant site from which the first biopsy was obtained. Each biopsy was divided into 1 mesial and 1 distal portion. The mesial tissue portion was fixed in a buffered fixative and embedded in EPON. Sections were produced, stained in PAS and toluidine blue and used for histometric and morphometric analyses. The distal portion of the biopsies were embedded, snap frozen in liquid nitrogen and stored in a freezer at -70 degrees C. From each tissue portion, 15 sections were prepared in a cryostat and exposed to immunohistochemical staining. A panel of monoclonal antibodies was used and the avidin-biotin method for staining was applied. The sections were examined morphometrically. Both tissues harbored a well keratinized oral epithelium and a connective tissue, the composition of which was close to identical in terms of collagen, cells and vascular structures. The peri-implant mucosa, however, also included a junctional epithelium which evidently allowed the penetration of products from the oral cavity. As a consequence, the periimplant mucosa in comparison to the masticatory mucosa was found to contain significantly enhanced numbers of different inflammatory cells.