Four clinical centers, using the Brånemark System and with personnel trained in the use of Gore-Tex Augmentation Material (GTAM), participated in a prospective study of 45 patients 18 to 83 years of age. A total of 55 implants were placed with membranes because of local bony defects (fenestration or dehiscence). Dehiscence and fenestration defects were evaluated as one group. The mean initial defect height was 4.7 mm (SD = 3.0). After healing, the remaining defect height was reduced to 1.1 mm (SD = 2.3). The decrease in surface exposure was significant. Complications were primarily attributed to exposure of six membranes during the early healing period. The cumulative survival rate was 84.7% in maxillae and 95.0% in mandibles after 2 years of follow-up. The surgical application of GTAM to produce bone in localized bony defects around oral implants seems to be a predictable method that may reduce the need for extensive augmentation surgery in patients with insufficient jaw bone volume.

Adolescent↗

PubMedDate not supplied

Variations in bone regeneration adjacent to implants augmented with barrier membranes alone or with demineralized freeze-dried bone or autologous grafts: a study in dogs.

A study was performed in two large hound dogs to evaluate the bone-induction potential of demineralized freeze-dried bone (DFDBA) placed into defects adjacent to implants that were placed into extraction sockets. Two implants were untreated controls, two implants received only Gore-Tex Augmentation Membrane (GTAM), two implants received GTAM and autologous bone, and six sites received GTAM and DFDBA. DFDBA was prepared from the long bones of a dog of the same breed as the experimental dogs. P2, P3, and P4 were extracted bilaterally, and buccal defects were created and measured. Twelve commercially pure titanium Brånemark implants were placed. At 12 weeks, clinical measurements were taken and the dogs were sacrificed. The untreated control defects had a mean clinical bone fill of 1.75 mm (37%). Sites treated with autologous bone had a mean of 5.0 mm (95%) of clinical bone fill within the original defects. Sites treated with DFDBA and barriers had 3.8 mm (75%) of bone fill, while sites treated with membranes alone had a mean of 4.2 mm (80%) of bone fill. Histologic evaluation revealed that DFDBA sites had retained nonviable bone chips in 45.4% of the bone matrix, and only 8.3% was lamellar bone. Autologous graft sites had 26.2% retained bone chips within the bone matrix, and 61% percent of the matrix consisted of lamellar bone. For GTAM-only sites, 70.2% of the matrix was lamellar bone and 29.8% was woven bone. Retained DFDBA bone chips were nonviable, occasionally surrounded by woven bone, and appeared to break up and then remineralize without the presence of osteoclastic or osteoblastic activity. Retained autologous bone chips were surrounded and incorporated by the host bone. The autologous bone grafts and DFDBA implants were considered to be osteoconductive. For the three treatment groups, within the defects there were sparse bone-implant contacts. The results indicate that GTAM barriers alone or with autologous bone grafts produced the best clinical and histologic results. DFDBA did not appear to induce bone formation in any of the evaluated specimens.

Alveolar Process↗

PubMedDate not supplied

The use of e-PTFE barrier membranes for bone promotion around titanium implants placed into extraction sockets: a prospective multicenter study.

This multicenter study was conducted to determine the predictability for implants placed into immediate extraction sockets and augmented with e-PTFE barrier membranes. Forty-nine implants were placed in immediate extraction sockets. Initial and final defect measurements and the number of threads exposed were compared. Patients were followed up to 1 year after implant loading. Three implants were lost at the abutment connection surgery. The 1-year survival rate was 93.9%. Twenty barrier membranes became exposed and were removed prior to stage 2 surgery, while the remaining barriers were removed at abutment connection. The average defect bone formation for membrane-retained sites was 4.8 mm, while the average bone formation for sites in which the membranes were prematurely removed was 4.0 mm (P < .0001). At stage 2 surgery there was an average of 0.6 threads exposed (P < .001) for the membrane-retained sites and 2.6 threads for the early removal sites (NS). Forty-five pairs of nonstandardized radiographs were evaluated for bone loss after implant loading (average 7.5 months). The mesiodistal bone loss averaged 0.72 mm. Within the limits of this study, e-PTFE membranes will promote clinically and statistically significant amounts of bone around immediately placed implants. Retention of e-PTFE barriers until stage 2 surgery improves the amount of bone promoted around the implants.

Adult↗

PubMedDate not supplied

Flap designs for minimization of recession adjacent to maxillary anterior implant sites: a clinical study.

The purpose of this study is to present new flap designs for the prevention of postoperative gingival recession adjacent to maxillary anterior sites that received dental implants. Nine patients received 10 implants in the maxillary anterior region. Gingival morphotypes and smile lines were evaluated prior to implant placement. Gingival probing depths, clinical attachment levels, and recession were recorded at teeth adjacent to implant sites at the initial exam and 3 months after implant restoration. A minimum of 5 mm of crestal bone width was required for implant placement. The labial flaps for healed ridges and implants placed into sockets were extended to or within 1 to 3 mm beyond the alveolar crest. In two sites, transfer of the implant relationships was made to provide the patients with provisional restorations at the time of second-stage surgery. Four patients had implants placed at the time of tooth removal. In these patients, expanded polytetrafluoroethylene barrier membranes were modified, removing the outer rim of material. The inner portion of the material was placed over the implant and the flaps were sutured, leaving the center part of the material exposed. The purpose of using the barrier in this manner was to protect the clot and subsequent granulation tissue formation during the first 2 weeks of healing. The material was removed 2 weeks after surgery. Six implants were placed into edentulous sites. At second stage surgery, flaps were reflected to the alveolar crest, thereby minimizing the potential for gingival recession. Provisional restorations placed at the time of implant uncovering appeared to support the repositioned gingiva. Changes in probing depth, clinical attachment levels, and recession were not statistically or clinically significant. Results of this pilot project suggest that flap designs minimized recession at teeth next to implant sites.

Alveolar Process↗

PubMedDate not supplied

Soft tissue and marginal bone conditions at osseointegrated implants that have exposed threads: a 5-year retrospective study.

The purpose of this retrospective clinical investigation was to study possible soft tissue complications and marginal bone resorption related to exposed threads of osseointegrated Brånemark oral implants during a 5-year period. Group 1 comprised 27 patients with 38 test implants that had not become completely covered with bone at implant placement. Thirty control implants in 25 of the patients were each next to a test implant and had no exposed threads initially. Group 2 comprised 51 patients with 107 test implants that had developed marginal bone loss beyond the second thread, as judged radiographically at the first annual checkup. Forty-eight control implants showed no or minor marginal bone resorption up to the first thread. Initial marginal defects and fenestrations at Brånemark implants (group 1) did not lead to mucosal problems or progressive marginal bone resorption during the first 5 years of function. Moreover, bone resorption, seen after the first year of loading at initially completely bone-covered implants, did not lead to any specific soft tissue problems, nor did it result in any further progressive bone resorption during a subsequent 4-year period. Based on the observed low incidence of soft tissue pathology at implants with exposed threads, it is suggested that bone augmentation techniques in the situations studied be used with restriction.

Adolescent↗

PubMedDate not supplied

Vestibular-neck interaction and transformation of sensory coordinates.

The article considers findings and concepts on vestibular-proprioceptive interaction for self-motion perception and postural control under the form of simple describing models. It points out that vestibular-neck interaction is only a small fraction of an extended mechanism of co-ordinate transformations. This links together the different parts of our bodies, so that sensory information arising in one part of the body can be used for perceptual or motor tasks in other parts. Particular emphasis is put on the problems that arise from imperfect signal transduction in the vestibular semicircular canal systems at low stimulus frequencies/velocities. Also, a "down-and-up-channeling" principle is suggested, by which the body support is linked via coordinate transformations to the internal notion of physical space provided by the vestibular system. Furthermore, the following question is addressed: how does the brain use visual input to overcome the vestibular deficiencies, at the risk of visual self-motion illusions? Finally, a conceptual model of postural control is presented in which a proprioceptive feedback loop that links the body to its support surface is merged with a loop for postural stabilization in space.

Humans↗

PubMedDate not supplied

One-step surgical placement of Brånemark implants: a prospective multicenter clinical study.

This prospective longitudinal multicenter study evaluated the clinical outcomes after placement and restoration of one-step Brånemark implants into the maxillae and mandibles of completely and partially edentulous patients. Six surgical treatment centers participated in this study, in which 135 implants were placed into 63 adult patients. All implants were stable after placement. The majority of implants were placed into type B bone with minimal jaw resorption and type 2 bone quality. After implant placement, standard transmucosal healing abutments were firmly placed. The average amount of time between implant placement and prosthetic abutment connection was 170 days in the maxillae and 147 days in the mandibles. To evaluate crestal bone changes caused by implant placement, a periodontal probe was used to measure midbuccally from the top of the implant cylinder to the alveolar crest; in 29 patients, 54 midbuccal bone crest sites were remeasured following prosthetic abutment connection. Crestal bone changes in mandibles and maxillae were statistically and clinically insignificant. Six implants were lost prior to loading and one implant has not been restored. No implants or restorations were lost after loading. At 1 year, the implant success rate was 95.6%. Mesiodistal radiographic measurements from 34 patients were averaged, and changes from prosthetic abutment connection to, on average, 12 months follow-up were compared. The radiographs, which were digitalized, measured from the bottom of the implant cylinder to the most coronal bone in contact with implant thread. For mandibular implants, the mean radiographic bone level at prosthetic abutment connection was 1.07 mm; after loading, it was 1.35 mm. For maxillary implants, the mean radiographic bone height at prosthetic abutment connection was 1.16 mm; after loading, it was 1.36 mm. These changes were not statistically significant. The 1-year outcomes from this patient series indicate that one-step Brånemark implants provide excellent clinical results when placed in patients with good bone quality and quantity.

Adult↗