The International Journal of Oral & Maxillofacial Implants, 01/1994

In this study, standard and prototype reinforced e-PIFE membranes were used to evaluate the pattern of bone regeneration in membrane protected defects in the mandibles of four dogs. Following a healing period of 2 and 4 months, control sites without membranes exhibited incomplete osseous healing with a persisting defect. Test sites with membranes demonstrated significantly better bone healing, although bone regeneration was not yet completed at 4 months. The histologic evaluation showed that bone regeneration, once activated, progresses in a programmed sequence through a series of maturation steps, which closely resemble the pattern of bone development and growth. Keywords: bone defects, bone healing, guided bone regeneration, membranes

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. Keywords: bone promotion, e-PTFE barrier membranes, immediate implants

Osteoinductive implantable materials have been a subject of basic science research in clinical implantology. This study examined the osteoinductive effect of an implantable material produced by osteoblastic cells that were isolated in the laboratory from mouse calvaria. After 21 days in culture, osteoblastic cells formed a thin film that could be easily manipulated. This thin film was subjected to freezing and thawing and was implanted in mouse muscle tissue. Osteoblastic cells were strongly positive for alkaline phosphatase reactivity and Von Kossa stain in vitro. Collagen type I, osteocalcin (BGP), and alkaline phosphatase were identified at the immunohistochemical electron microscopic level. Histologic findings showed an osteoinductive effect of the implanted material. The results strongly suggest the possibility of producing an osteoinductive implantable material by culturing osteoblastic cells in vitro. Keywords: culture, osteoblastic cell, osteoinductive implantable materials

After 3 years, 82 of the original 92 patients remain in this prospective multicenter study of single-tooth restorations supported by Brånemark implants. Since the l-year follow-up, 6 more patients have been lost, but no additional implants have failed in those patients examined at the 3-year follow-up visit. After 1 year of function, 97.2% of the implants survived in 88 patients, and between the 1- and 3-year follow-up, 100% survived in 82 patients, giving a 3-year cumulative success rate of 97.2%. No changes were observed in the status of gingivitis, pocket depth, periodontal pocket bleeding index, and tooth and implant mobility from those reported after 1 year. Marginal bone resorption remained at a low level-less than 0.1 mm annually during the second and third years. Abutment screw loosening continued, but at a significantly reduced rate from that reported after 1 year. When used, gold rather than titanium abutment screws remained secure. Keywords: multicenter study, single-tooth implants

The dynamic relation of the anteroposterior and rotational growth of the mandible to the transverse arch width and dental height changes must be understood before placing endosseous implants in actively growing patients. Research models demonstrate that osseointegrated implants lack the compensatory growth mechanism of the natural dentition. Remodeling associated with skeletal growth in the region of the implant placement site could cause the implant to either become unsupported by bone or submerged within it. Implants placed after age 15 in girls and 18 in boys have the most predictable prognosis. When placed in the growing patient, dental implants should be closely monitored and carefully restored with implant prostheses designed to accommodate growth and development. Keywords: dental implants, growth and development, mandibular growth, osseointegration

The capacity of dentate subjects to discriminate the thickness of objects placed between the teeth seems to depend on receptors in the periodontal ligament and muscles. The compensatory mechanism of ankylotic implants for the function of missing periodontal ligaments is not yet known. To investigate this question in overdenture wearers, 26 patients with ITI implants and 20 patients with natural roots were selected. According to the experimental protocol, the discriminatory ability was recorded with 10 steel foils (thickness ranging from 10 to 100 µm) placed between the premolars. Each thickness was tested 10 times and the test subjects were required to distinguish whether foil was positioned between the teeth. A maximum of 100 correct or 100 incorrect answers was possible. The average number of incorrect answers was significantly higher in test subjects with implants. The 50% limit (i.e., the tested thickness recorded with at least 5 wrong answers) was established, but no statistically significant difference was found. In both groups, the critical tactile threshold of perceived thickness was 30 to 40 ¡µm, with 2 being the average number of incorrect assessments. When comparing the minimal thickness, which was recorded without incorrect assessment, a significantly lower threshold was observed on patients with natural roots. Thus, active tactile sensibility appears to depend onthe receptors in the periodontal ligament. However, wearing of removable prostheses is a modifying factor and may influence the oral tactile sensibility for both groups. Keywords: implants, overdentures, roots, tactile threshold

Clinical studies have reported a positive correlation between the surface roughness of teeth or implants and the rate of supragingival and subgingival plaque maturation. This study compared the surface characteristics of abutments from different implant systems (Astra Tech, Bonefit, Brånemark, Core-Vent, IMZ, and Steri-Oss}. Foreach system, two abutments were examined for surface roughness and surface hardness. The latter served as an indicator for resistance against roughening during professional or habitual oral hygiene procedures. The Ra values (in µm) of the tested abutments were: Steri-Oss, 0.10; IMZ, 0.14; Brånemark, 0.21; Bonefit, 0.23; Astra Tech, 0.27; and Core-Vent, 0.30. The Vickers hardness scores (in VHN) were: Brånemark, 154; IMZ, 208; Astra Tech, 258; Bonefit, 292; Core-Vent, 304; and Steri-Oss, 340. In comparison to most metallographically polished composites, titanium abutments showed a higher initial surface roughness and a slightly higher surface hardness. This may explain, besides the known high surface free energy of titanium, rapid plaque growth on these abutments. Keywords: implants, microbiology, plaque formation, surface characteristics, surface roughness, surface hardness

A technique was developed for the fabrication of an anterior single-tooth restoration supported by a malaligned endosseous implant. Patient treatment included the application of this original technique, which can be used in both anterior and posterior sections of the arch. Keywords: malaligned implant, restoration, single-tooth implant

Complications were recorded in consecutive patients with osseointegrated implant-supported prostheses visiting prosthodontic specialist clinics during October and November 1991. Patients at regular follow-ups and emergency visits were included. Of the 600 prostheses examined, 28% needed some prosthodontic treatment. Complications varied widely-from simple adjustment to complete remaking of the prosthesis. The most common complications observed were related to the acrylic resin part of the prostheses. The frequency was higher in maxillary than in mandibular prostheses, and in full-arch removable and fixed prostheses than in single-tooth replacements and fixed partial dentures. Implant losses were rare (0.3% of all 2,709 implants placed) and occurred in 1% of the patients examined. Keywords: dental implants, dental materials, denture, partial, fixed, denture, partial, removable, practice management, dental

This study investigated the association of patient and provider characteristics on dental implant performance and survival probabilities. The outcomes of interest in this study were implant failures and peri-implant tissue health status. Univariate and bivariate statistics were used to describe the study population and to assess association of outcomes with patient and facility characteristics. Data were gathered from the period 1985 through January 1, 1990, from the Department of Veterans Affairs Dental Implant Registry. Logistic regression models were used to relate the outcomes with independent variables. Results showed that implant survival is associated with (1) the medical status of the patient, (2) the surface coating material of the implant, and (3) implant surgical and healing complications. Peri-implant soft tissue health was associated with (1) patient's use of tobacco, (2) surface coating of implants, and (3) implant provider's experience. Keywords: dental implants, epidemiology, longitudinal study, regression analysis

Sixty-one patients participated in a longitudinal study designed to compare the psychological effects of osseointegrated implants with those of conventional denture replacements. Thirty-two patients who requested either relining or reconstruction of their dentures were asked to complete questionnaires designed to measure their psychological well-being while they were on a waiting list and then again 6 months after treatment. Their responses were compared with those of 29 patients who had received an osseointegrated implant. While the implant patients had reported significant declines in psychological distress, there was no such change for the denture patients. Although both groups experienced fewer disabling symptoms, the decline was greater for the implant group. Finally, neither group showed evidence of any change in self-esteem. The results suggest that osseointegrated implants can have a more positive effect on well-being than denture replacements. Keywords: dentures, osseointegrated implants, psychological effects

Dilantin sodium is a commonly used anticonvulsive agent. A well-known side effect of this medication is hyperplasia of gingival tissues. This hyperplasia has also been reported in mucosa beneath complete dentures and has been related to poor oral hygiene. This case report describes hyperplasia of tissues around titanium implants in a patient taking Dilantin sodium to prevent epileptic seizures. The excess tissue was removed and hygiene reinforced. NO recurrence of the tissue enlargement is evident after 1 year. Keywords: Dilantin, hyperplasia, implant