Elena Linder

Bio-Oss® Collagen in the buccal gap at immediate implants: a 6-month study in the dog

BACKGROUND following tooth extraction and immediate implant installation, the edentulous site of the alveolar process undergoes substantial bone modeling and the ridge dimensions are reduced. objective: the objective of the present experiment was to determine whether the process of bone modeling following tooth extraction and immediate implant placement was influenced by the placement of a xenogenic graft in the void that occurred between the implant and the walls of the fresh extraction socket. MATERIAL AND METHODS five beagle dogs about 1 year old were used. The 4th premolar in both quadrants of the mandible ((4) P(4) ) were selected and used as experimental sites. The premolars were hemi-sected and the distal roots removed and, subsequently, implants were inserted in the distal sockets. In one side of the jaw, the marginal buccal-approximal void that consistently occurred between the implant and the socket walls was grafted with Bio-Oss Collagen while no grafting was performed in the contra-lateral sites. After 6 months of healing, biopsies from each experimental site were obtained and prepared for histological analyses. RESULTS the outline of the marginal hard tissue of the control sites was markedly different from that of the grafted sites. Thus, while the buccal bone crest in the grafted sites was comparatively thick and located at or close to the SLA border, the corresponding crest at the control sites was thinner and located a varying distance below SLA border. CONCLUSIONS it was demonstrated that the placement of Bio-Oss Collagen in the void between the implant and the buccal-approximal bone walls of fresh extraction sockets modified the process of hard tissue healing, provided additional amounts of hard tissue at the entrance of the previous socket and improved the level of marginal bone-to-implant contact.

Effect of a xenograft on early bone formation in extraction sockets: an experimental study in dog

AIM The aim of this study was to study the effect on early bone formation resulting from the placement of a xenograft in the fresh extraction socket in dogs. MATERIAL AND METHODS Five beagle dogs were used. The distal roots of the third and fourth mandibular premolars were removed. In one quadrant, a graft consisting of Bio-Oss Collagen was placed in the fresh extraction wound, while the corresponding premolar sites in the contra-lateral jaw quadrant were left non-grafted. After 2 weeks of healing, the dogs were perfused with a fixative, the mandibles removed, the experimental sites dissected, demineralized, sectioned in the mesio-distal plane and stained in hematoxyline-eosine. RESULTS The central portion of the non-grafted sockets was occupied by a provisional matrix comprised of densely packed connective tissue fibers and mesenchymal cells. Apical and lateral to the provisional matrix, newly formed woven bone was found to occupy most of the sockets. In the apical part of the grafted sockets, no particles of the xenograft could be observed but newly formed bone was present in this portion of the experimental site. In addition, limited numbers of woven bone trabeculae occurred along the lateral socket walls. The central and marginal segments of the grafted sockets, however, were occupied by a non-mineralized connective tissue that enclosed Bio-Oss particles that frequently were coated by multinucleated cells. CONCLUSIONS The placement of Bio-Oss Collagen in the fresh extraction wound obviously delayed socket healing. Thus, after 2 weeks of tissue repair, only minute amounts of newly formed bone occurred in the apical and lateral borders of the grafted sockets, while large amounts of woven bone had formed in most parts of the non-grafted sites.

Deposition of nanometer scaled calcium‐phosphate crystals to implants with a dual acid‐etched surface does not improve early tissue integration

OBJECTIVE To evaluate hard and soft tissue healing to implants with a dual acid-etched surface with and without deposition of calcium-phosphate crystals. MATERIALS AND METHODS Three months after extraction of mandibular premolars in six Labrador dogs, four osteotomy preparations, 8 mm deep and 3 mm wide, were performed. The prepared canals were widened in the marginal 4 mm zone to 3.74 mm. Implants with an 8 mm long and 3.75 mm wide intraosseous portion and a 5.0 mm high and 4.0 mm wide transmucosal part were placed in such a way that the base of the wider neck-portion of the implant coincided with the crestal bone. The implants were dual acid - etched (Osseotite(®); Biomet 3i). The surface of the test implants was, in addition, modified by a discrete deposition of calcium-phosphate crystals (Nanotite™; Biomet 3i). Every second implant placed was a test unit. After 2 weeks the implant installation procedure was repeated in the opposite side of the mandible. Two weeks later the animals were euthanized and biopsies were obtained and prepared for histological analysis. RESULTS The degree of bone-to implant contact (BIC%) was larger at implants without (Osseotite) than in those with (Nanotite) calcium-phosphate crystals. No differences were found regarding soft tissue dimensions and composition between the two types of implants. CONCLUSION It is suggested that deposition of nanometer-sized calcium-phosphate crystals to implants with a dual acid-etched surface does not improve early tissue integration.

Healing at implants placed in an alveolar ridge with a sloped configuration: an experimental study in dogs.

PURPOSE To study healing around implants placed in an alveolar ridge with a sloped lingual-buccal configuration. MATERIALS AND METHODS Six Labrador dogs were used. Buccal bone defects were prepared in the mandible after extraction of premolars. Three months later, two test implants with a sloped marginal design and two control implants were placed in the chronic defect area with a sloped lingual-buccal configuration of each premolar region. The test implants were placed in such a way that the buccal margin of the implant coincided with the buccal bone crest. The lingual margin of the control implants was placed to a similar depth as the lingual margin of the test implants. Abutments were connected to the implants in the right mandibular premolar region and flaps were sutured around the neck of the abutments. In the left side of the mandible, cover screws were placed and the flaps were sutured to cover the implants. Biopsies were obtained 4 months later and prepared for histological examination. RESULTS It was demonstrated that healing around implants placed in an alveolar ridge with a sloped lingual-buccal configuration resulted in the preservation of a vertical discrepancy between the lingual and buccal marginal bone levels around implants with either a regular cylindrical outline or a modified marginal portion that matched the slope of the alveolar ridge. CONCLUSION As the marginal buccal portion of the control implants with a regular design had no bone support, it is suggested that implants with a modified marginal portion may be considered in recipient sites with a sloped lingual-buccal configuration.