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Biomedical subjects

D Buser

Publications and source records attributed to D Buser.

At least 73 records · Page 4Linked to original sources
PubMed1994

Advances in the use of guided tissue regeneration for localized ridge augmentation in combination with dental implants.

Osseointegrated dental implants placed into adequate bone enjoy a high success rate. However, placing implants into resorbed alveolar ridges can result in fixtures that are not optimally positioned or must be placed in insufficient bone, thus reducing their rate of success. Recently, techniques for bone regeneration developed for use around teeth have been applied to implant dentistry. Guided Tissue Regeneration (GTR), also called Guided Bone Regeneration (GBR), uses thin membranes which act as barriers to soft tissue ingrowth. This approach for regenerating bone around implants is described in detail in this paper. Initial approaches and modifications are covered as are specific details of current techniques.

Alveolar Bone Loss↗
PubMed1994

Tissue integration of one-stage implants: three-year results of a prospective longitudinal study with hollow cylinder and hollow screw implants.

Tissue integration of one-stage, nonsubmerged ITI implants over a 5-year period is documented. Fifty-four implants were placed in 38 partially edentulous patients. No implants had detectable mobility after a healing phase of at least 3 months, and there were no clinical signs of peri-implant infection. Radiographs revealed no peri-implant radiolucencies and all implants were in favorable positions for fixed prosthetic restorations. Following completion of the prosthetic treatment, all patients were placed in 3-month oral hygiene recall programs. Annual dental examinations included evaluation of each implant according to fixed criteria. Three years after implant placement, 51 of 53 implants (96.2%) were evaluated as successful (one patient was lost to the study). Acute peri-implant infections were associated with two implants; both were classified as late failures. The results demonstrated that one-stage transgingivally healing ITI implants integrate dependably in the tissue and that successful tissue integration can be maintained for at least 3 years.

Chi-Square Distribution↗
PubMed1993

Evaluation of guided bone generation around implants placed into fresh extraction sockets: an experimental study in dogs.

Immediate placement of implants into fresh extraction sockets would have the principal advantage of decreasing the recommended period of healing. It also would result in a guided placement of the implant, and it could reduce the resorption of the alveolar bone in the extraction area. However, when an implant is placed immediately into an extraction socket, it may not engage the walls of the socket near the crest of the alveolar ridge. With the presence of a bone defect around an implant, ingrowth of soft tissue could compromise the achievement of osseointegration in the crestal bone area. The objective of this study was to evaluate the crestal bone healing response adjacent to implants placed immediately into fresh extraction sockets with and without covering membranes. Eight adult mongrel dogs had the third and fourth mandibular premolars extracted bilaterally. Thirty-two submerged titanium hollow-screw implants were inserted immediately into the extraction sockets. On the right side, the implants were covered with an expanded polytetrafluorethylene membrane, whereas the left side served as a control. One dog was killed after 2 weeks, one after 4 weeks, and six after 12 weeks. Soft tissue dehiscence developed over 10 implants (12-week dogs) covered with membranes. Dehiscence was noted histologically over three contralateral control implants. When soft tissue dehiscence occurred and the membrane was left exposed without oral hygiene during healing, the degree of bone integration was significantly less than in the control sites without membranes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Localized ridge augmentation using guided bone regeneration. 1. Surgical procedure in the maxilla.

A new surgical technique for localized ridge augmentation prior to the placement of dental implants has been developed. The technique is based on the principle of guided bone regeneration utilizing barrier membranes. In the present article, the currently used surgical procedure is presented through two case reports. In addition, the different aspects of the surgical technique needed to achieve a predictable success are discussed.

Adolescent↗
PubMed1992

Radiographic evaluation of crestal bone levels adjacent to nonsubmerged titanium implants.

Several parameters have been described to determine success or failure in long-term evaluations of dental implants. One of these parameters is the observation of changes in peri-implant bone levels. Studies on submerged implants have analyzed the bone level changes in the pre- and post-loading phases. No such data exist for intentionally nonsubmerged implants. The purposes of this study were: (1) to test the applicability and reproducibility of a simple computer-assisted method in the evaluation of changes in peri-implant bone levels; (2) to establish a baseline for the longterm radiographic follow-up; and (3) to evaluate changes in crestal bone levels adjacent to nonsubmerged ITI implants between the 1-year and 2-year examination. Standardized periapical radiographs were obtained from 80 implants at the 1-year and 2-year follow-up examinations after their placement. The implants were located in different jaw areas of 55 patients and supported single crowns or short-span fixed partial dentures. For each implant, the distance from implant shoulder to first crestal bone contact (DIB) was measured at the proximal surfaces with a digitizer/computer assembly. Statistically significant greater mean DIB were found at the 1-year (baseline) evaluation for: (1) maxillary sites overall (4.10 x 1.02 mm (SD)) compared with mandibular sites overall (3.61 +/- 1.03 mm); (2) maxillary anterior sites (4.08 +/- 0.97 mm) compared with mandibular posterior sites (3.60 +/- 1.05 mm); and (3) maxillary posterior sites (4.13 +/- 1.12 mm) compared with mandibular posterior sites. No statistically significant changes in DIB occurred in any of the jaw locations between the 1-year and 2-year evaluations.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Bone Loss↗
PubMed1992

Light and transmission electron microscopy of the intact interfaces between non-submerged titanium-coated epoxy resin implants and bone or gingiva.

This experiment was aimed at studying the intact tissue/implant interface of non-submerged dental implants with a titanium surface. Epoxy-resin replicas were fabricated from 3.05 x 8 mm cylindrical titanium implants with a plasma-sprayed apical portion and a smooth coronal collar. The replicas were coated with a 90-120-nm-thick layer of pure titanium and autoclaved. The coated replicas were inserted as non-submerged endosseous implants in the edentulous premolar region of dog mandibles and allowed to heal for three months. Jaw sections containing the implants were processed for light and electron microscopic study of the intact tissue/implant interface with and without prior demineralization. Gingival connective tissue fibers were closely adapted to the titanium layer, in an orientation more or less parallel to the implant surface. There was no evidence of any fiber insertions into the surface irregularities of the smooth or rough titanium surface. Undemineralized bone was intimately adapted to the titanium surface without any intervening space. In demineralized sections, the collagen fibers of the bone matrix tended to be somewhat thinner and occasionally less densely packed in the vicinity of the implant surface. However, they extended all the way to the titanium surface, without any intervening fibril-free layer.

Alveolar Process↗
PubMed1992

Soft tissue reactions to non-submerged unloaded titanium implants in beagle dogs.

The soft tissue reactions to non-submerged unloaded titanium implants were examined. A total of 24 implants were placed in 6 beagle dogs. The implants differed in their crestal area by having either a rough sandblasted, a fine sandblasted, or a polished surface. After 3 months, all implants were firmly anchored in the bone and had no clinical signs of peri-implant inflammation. Undecalcified histologic sections demonstrated that all implants achieved osseointegration with direct bone contact. The epithelial structures showed a peri-implant sulcus with a non-keratinized sulcular epithelium and a junctional epithelium. None of the sections exhibited epithelial downgrowth to the alveolar crest. In the supracrestal area, a direct connective tissue contact to the implant post was observed. An approximately 50 to 100 microns wide zone of dense circular fibers was found close to the implant surface. It was free of blood vessels and resembled closely an inflammation-free scar tissue formation. This zone was surrounded by a looser connective tissue with a 3-dimensional network of collagen fibers running in different directions. No significant differences concerning soft tissue reactions were found between the 3 implant surfaces. In particular, the length of direct connective tissue contact was similar. Concerning bone reactions, a significantly shorter distance from the top of the implant to the most coronal bone-implant contact was observed for rough surfaces. It is concluded that non-submerged unloaded titanium implants achieved a complication-free tissue integration with a dense connective tissue in direct contact to the implant surface in the supracrestal area, and epithelial structures similar to those around natural teeth. The different surface textures did not influence the healing pattern of the soft tissues, but had an influence on the location of the most coronal bone-implant contact.

Alveolar Process↗
PubMed1991

Influence of surface characteristics on bone integration of titanium implants. A histomorphometric study in miniature pigs.

The purpose of the present study was to evaluate the influence of different surface characteristics on bone integration of titanium implants. Hollow-cylinder implants with six different surfaces were placed in the metaphyses of the tibia and femur in six miniature pigs. After 3 and 6 weeks, the implants with surrounding bone were removed and analyzed in undecalcified transverse sections. The histologic examination revealed direct bone-implant contact for all implants. However, the morphometric analyses demonstrated significant differences in the percentage of bone-implant contact, when measured in cancellous bone. Electropolished as well as the sandblasted and acid pickled (medium grit; HF/HNO3) implant surfaces had the lowest percentage of bone contact with mean values ranging between 20 and 25%. Sandblasted implants with a large grit and titanium plasma-sprayed implants demonstrated 30-40% mean bone contact. The highest extent of bone-implant interface was observed in sandblasted and acid attacked surfaces (large grit; HCl/H2SO4) with mean values of 50-60%, and hydroxylapatite (HA)-coated implants with 60-70%. However, the HA coating consistently revealed signs of resorption. It can be concluded that the extent of bone-implant interface is positively correlated with an increasing roughness of the implant surface.

Animals↗
PubMed1991

Effects of the platelet-derived growth factor/insulin-like growth factor-I combination on bone regeneration around titanium dental implants. Results of a pilot study in beagle dogs.

The purpose of this study was to evaluate the early wound healing events of bone around press-fit titanium implants inserted with and without the concurrent application of a combination of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-I). Nine months prior to implant placement all mandibular premolar teeth were extracted in 8 beagle dogs. Subsequently, 40 specially manufactured titanium implants with 2 transverse holes in the apical section were press fit into precise recipient sites in the dogs' mandibles. The dogs were sacrificed at 7 and 21 days following implant placement yielding 12 PDGF-B/IGF-I treated and 8 control (placebo gel or non-treated) implants for each observation period. Coded undecalcified sections were analyzed for: 1) percentage of implant surface in contact with new bone; 2) percentage of peri-implant space filled with new bone; and 3) percentage of implant hole filled with new bone. An analysis of variance was used to determine significant differences among the treatment groups. At 7 days, the percentage of bone fill in the peri-implant spaces and the percentage of implant surface in contact with new bone were both significantly increased in PDGF-B/IGF-I treated sites (P less than 0.01 for both groups). There was less than 1.5% fill of the implant holes in both treated and control sites (no significant differences). At 21 days the percentage of bone fill in the peri-implant spaces was significantly increased in the PDGF-B/IGF-I treated sites (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Digital subtraction radiography for the assessment of changes in peri-implant bone density.

Digital subtraction radiography is proposed as a potential diagnostic tool for implant research and patient monitoring. Examples of the application of this technique are given observing peri-implant density changes during the early healing phase and during ligature-induced peri-implantitis in an animal model. Additional cases document the loss of peri-implant bone density associated with an infection and increase in density caused by remodeling after functional loading of an implant with a single crown. Digital subtraction radiography might be one of the most sensitive noninvasive methods for assessing subtle density changes in peri-implant tissues, providing additional diagnostic information on implant tissue integration and maintenance.

Alveolar Bone Loss↗
PubMed1991

Tissue integration of one-stage ITI implants: 3-year results of a longitudinal study with Hollow-Cylinder and Hollow-Screw implants.

This study examined the tissue integration of one-stage, nonsubmerged ITI implants over a period of 3 years. Fifty-four implants were placed in 38 partially edentulous patients. Following healing (at least 3 months), all 54 implants were free of peri-implant infections and revealed no detectable mobility. Radiographs showed no signs of peri-implant radiolucencies, and the implants were in favorable positions for prosthetic restoration. Following incorporation of fixed partial dentures, patients were enrolled in a hygiene recall program with 3-month intervals and were examined once a year. Based on predefined criteria, each implant was classified as successful or failing. After the 3-year observation period, 51 of 53 implants (96.2%) were considered successfully integrated. (One patient with one implant dropped out of the study.) Two implants exhibited recurrent peri-implant infections and were classified as late failures. These results indicate that one-stage ITI implants can achieve successful tissue integration on a predictable basis and that it can be maintained over a period of at least 3 years.

Dental Implants↗
PubMed1990

Regeneration and enlargement of jaw bone using guided tissue regeneration.

The purpose of this study was to present the surgical procedures and the clinical results of guided tissue regeneration (GTR) treatment aimed at regenerating local jaw bone in situations where the anatomy of the ridge did not allow the placement of dental implants. 12 patients were selected for ridge enlargement or bony defect regeneration. A combined split- and full-thickness flap was raised in areas designated for subsequent implant placement. Following perforation of the cortical bone to create a bleeding bone surface, a PTFE membrane was adjusted to the surgical site in such a way that a secluded space was created between the membrane and the subjacent bone surface in order to increase the width of the ridge or to regenerate bony defects present. Complete tension-free closure of the soft tissue flap was emphasized. Following a healing period of 6 to 10 months, reopening procedures were performed and the gain of bone dimension was assessed. In 9 patients with 12 potential implant sites, a sufficient bone volume was obtained to allow subsequent implant placement. The gain of new bone formation varied between 1.5 and 5.5 mm. In 3 patients, acute infections developed which necessitated early removal of the membranes and no bone regeneration could be achieved. The results of the study indicate that the biological principle of GTR is highly predictable for ridge enlargement or defect regeneration under the prerequisite of a complication-free healing.

Adolescent↗
PubMed1990

Tissue integration of non-submerged implants. 1-year results of a prospective study with 100 ITI hollow-cylinder and hollow-screw implants.

It has been postulated that the wound healing in a closed submerged location is one of the prerequisites for osseointegration of dental implants. The purpose of the present study was to evaluate the tissue integration of intentionally non-submerged titanium implants inserted by a one-stage surgical procedure. 100 ITI implants were consecutively placed in 70 partially edentulous patients. After a healing period free of masticatory loading for at least 3 months, the implants were examined. The clinical status showed for all implants neither detectable mobility nor signs of a peri-implant infection. Therefore, prosthetic abutments were inserted, and the patients were restored with fixed partial dentures. All patients were regularly recalled at 3-month intervals, and no patient dropped out of the study. Thus, all 100 implants were re-evaluated 12 months following implantation. Plaque- and sulcus bleeding indices, probing depth, clinical attachment level, width of keratinized mucosa, and periotest scores were assessed. In addition, standardized radiographs were analyzed for the presence of peri-implant radiolucencies and for the location of alveolar bone levels around the implants. Based on predefined criteria, the implants were classified as successful or failing. 98 implants were considered successful, and 1 implant failing. The remaining implant exhibited a peri-implant infection requiring local and systemic antimicrobial treatment. The results of this short-term study indicate that intentionally non-submerged ITI implants yield a high predictability for successful tissue integration.

Dental Implants↗