Biomedical subjects

Carlos E Nemcovsky

Publications and source records attributed to Carlos E Nemcovsky.

24 records · Page 2Linked to original sources

PubMed2002

Bovine-HA spongiosa blocks and immediate implant placement in sinus augmentation procedures. Histopathological and histomorphometric observations on different histological stainings in 10 consecutive patients.

Bovine mineral spongiosa block (B-SB) was used as a bone substitute in sinus augmentation procedures in 10 consecutive patients. Implants were placed during the same session. The purpose of this study was to histopathologically examine the healing of the grafted site around the implants at 12 months. Radiographic follow-up showed apparent bone apposition in the augmented area around the implants. Clinically, all 36 implants were stable and integrated with the surrounding tissue. Histopathologically, new bone formation was evident in all specimen hard tissue cores. Hydroxyapatite particles were present in direct contact with the remodeled osseous tissue. Mallory trichrome staining showed different stages of mineralization and maturation of the newly formed bone around the grafted mineral particles. Morphometric evaluation of Picrosirius red stained slides under polarized light microscopy was performed at the peripheral/external and deep section slides of all specimens. The average bone area fraction was 34.2%, with a 1 : 5.4 mean lamellar/woven bone ratio at the peripheral side and 53.0%, with 1 : 2.5 mean ratio at the deep side. The differences of both parameters between the two sites were statistically significant. B-SB proved to be a suitable grafting material with simultaneously placed implants in sinus floor augmentation procedures.

Adult↗

PubMed2002

Comparative study of buccal dehiscence defects in immediate, delayed, and late maxillary implant placement with collagen membranes: clinical healing between placement and second-stage surgery.

BACKGROUND: Implants can be placed at the time of tooth extraction (immediate), after several weeks (delayed), or after complete healing (late). The purpose of this study was to evaluate clinical bone healing of buccal dehiscence-type defects around maxillary implants placed together with bioabsorbable collagen barrier membranes and bone graft at the 3 time points. METHODS: Three implant placement protocols were compared: immediate procedures primarily closed by a rotated split palatal flap (19 patients, 23 implants; group 1); delayed sites closed by a rotated (full-thickness) palatal flap at the time of tooth extraction (25 patients, 39 implants; group 2); and late implantation (22 patients, 40 implants; group 3). One to 3 proximal implants were simultaneously placed. Defect height and width were measured at the time of implant placement and at second-stage surgery. Surface area was calculated as half ellipses. RESULTS: The best results were obtained with delayed implantation. The mean percentage of the reduced defect height for groups 1, 2, and 3 was 77.4%+/-16.92%, 88.8%+/-15.29%, and 75.2%+/-17.99%, respectively, and the mean percentage area of the reduced defect was 90.2%+/-9.15%, 95.6%+/-8.73%, and 87.6%+/-11.48%, respectively. Differences between groups were statistically significant. The mean percentage of the reduced defect height and area was significantly smaller when there was spontaneous implant cover screw exposure. Single rather than multiple implant placement led to significantly better results. CONCLUSIONS: Timing of placement, number of simultaneously placed implants, and spontaneous implant exposure significantly influence clinical bone healing around maxillary implants placed together with augmentation procedures.

Absorbable Implants↗

PubMed2002

Rotated palatal flap. A surgical approach to increase keratinized tissue width in maxillary implant uncovering: technique and clinical evaluation.

Although keratinized mucosa is not indispensible for the maintenance of periimplant tissue health if oral hygiene is adequate, its presence is generally advocated. The establishment of an adequate zone of gingiva that is firmly attached to the underlying periosteum and bone is important for the overall long-term success of implant-supported oral rehabilitation. The purpose of this study was to describe and evaluate a surgical approach for maxillary implant uncovering that augments the buccal periimplant keratinized tissue while avoiding a large zone of exposed implant-supporting bone by using a rotated palatal flap. The study comprised 40 implants that were uncovered in 13 patients using a combination of full-thickness buccally repositioned and rotated palatal flaps. Within each patient, the mean preoperative width of keratinized mucosa was 0.19 mm (SD 0.316), and the mean postoperative width was 3.45 mm (SD 0.489). The difference between post- and preoperative widths was 3.26 mm (SD 0.498), which was statistically significant according to a paired t test (P < .0001). The main advantages of this technique are simplicity and predictability, and it consistently provides a wider zone of keratinized gingiva in the buccal aspect of the future maxillary implant-supported restoration.

Dental Abutments↗

PubMedDate not supplied

Wide-diameter implant placement and internal sinus membrane elevation in the immediate postextraction phase: clinical and radiographic observations in 12 consecutive molar sites.

PURPOSE: To evaluate whether the combination of 5 surgical techniques in implant dentistry could be performed simultaneously in a predictable manner as effectively as each technique separately. MATERIALS AND METHODS: Immediately postextraction, 12 wide-diameter (WD) implants were placed in maxillary first or second molar sites. The residual vertical bone height ranged between 6 and 9 mm (average 7.8 mm). An internal sinus elevation, via the osteotomy site, was carried out in 10 sites using an osteotome tool implants were then self-tapped into the osteotomy site followed by Insertion of a customized healing screw. Consequently, horizontal gaps between the bony walls and the implant neck were filled by either bovine bone mineral or tricalcium phosphate particles. Full soft tissue closure around the healing cap screw was achieved by coronal positioning of the buccal flap. RESULTS: Soft tissue healing around the 12 implants was immaculate. In 10 sites, Internal osteotome sinus membrane elevation resulted in a height gain of between 2.5 and 6 mm (average 4.3 mm). Radiographically, bone-to-implant contact was evident. All implants were integrated and the prosthetic phase was completed after 6 months. DISCUSSION AND CONCLUSIONS: The combination of 1-stage technique and immediate placement of WD implants, along with internal sinus floor elevation and no soft tissue reflection at the time of implantation, is an achievable task and can be performed predictably. Time, cost, and morbidity are reduced, and the prosthetic solution is also eased for the benefit of the patient.

Adult↗

PubMedDate not supplied

Vertical ridge augmentation using xenogenic material supported by a configured titanium mesh: clinicohistopathologic and histochemical study.

PURPOSE: The aim of this study was to evaluate the capability of a configured titanium mesh (CTM) to serve as a mechanical and biologic device for restoring a vertically defected/resorbed alveolar ridge. MATERIALS AND METHODS: The study comprised 10 severely resorbed sites in 10 patients. Pre- and post-operative ridge measurements were taken with reference to the neighboring teeth and supporting screw head base of the CTM. Bovine bone mineral served as the augmentation filler material. The metal mesh was removed after 9 months. Subsequently, root-form, screw-type implants were placed. During the implant placement phase, cylindric bone samples were retrieved from the augmented area for histopathologic and histochemical examination. RESULTS: Upon soft tissue reflection and before augmentation, defect height, as recorded by a periodontal probe along the main threads exposed on the support screw, was between 5 and 8 mm (average 6.4 mm; SD +/- 1.17). At 9 months after augmentation, during the implant placement phase, the defect height was between 0 and 2 mm (average 1.2 mm; SD +/- 0.63). Differences were statistically significant (P < .001). Bone height gain was between 4 and 6 mm (average 5.2 mm, SD +/- 0.79), which gave an average bone fill of 81.2% (SD +/- 7.98). Polarizing microscopic examination of sections stained with Picrosirius red showed a gradual increase in new lamellar bone from coronal to apical cuts, reaching the highest area percentage in the deep apical zone. DISCUSSION: At 9 months postaugmentation using the CTM surgical technique, the quality and quantity of the newly established hard tissue appeared to be different in the coronal versus apical areas of the restored alveolar ridge. CONCLUSION: Although at 9 months postoperatively, the augmented alveolar ridge had different bone content, clinicohistochemical results demonstrated that this surgical technique could be a successful and predictable procedure for rebuilding a resorbed/defected ridge to accommodate endosseous implants.

Adult↗

PubMedDate not supplied

Biomaterial resorption rate and healing site morphology of inorganic bovine bone and beta-tricalcium phosphate in the canine: a 24-month longitudinal histologic study and morphometric analysis.

PURPOSE: An inorganic xenograft (inorganic bovine bone [IBB]) and a porous alloplast (beta-tricalcium phosphate [beta-TCP]) material were compared at different healing periods in experimental bone defects in dogs. MATERIALS AND METHODS: Six round defects, 5 x 4 mm, were made on the lateral bony mandibular angle in 8 dogs at different times. Two defects were randomly filled with IBB, 2 with beta-TCP, and 2 were left to blood clot. A bi-layer collagen membrane covered 1 defect of each type. Four specimens per treatment group were obtained for each treatment group at 3, 6, 12, and 24 months postoperatively. Morphometric analysis of decalcified (Donath technique) histologic slides was conducted using the measured areas of regenerated bone, grafted particles, and remaining concavity. RESULTS: In IBB sites, complete bone healing was evident at 12 and 24 months, but grafted particles dominated the sites. In beta-TCP sites, only particle remnants remained at 12 months. At 24 months, particles had completely resorbed in both membrane-protected (MP) and uncovered (UC) defects. Data were combined for final analysis since there were no statistically significant differences within each graft material group (MP or UC). Mean bone area fraction increased from 3 to 24 months at all sites. In bone area fraction a statistically significant difference was found between 3 and 6 months in the IBB and beta-TCP groups. IBB sites also showed such significance between 6 and 12 months. A statistically significant difference was found between MP ungrafted sites (42.9%) vs IBB (24.7%) and vs the control (24.8%) at 3 months. At 6 months, beta-TCP bone area fraction (68.8%) was significantly greater than IBB (47.9%) and control (37.5%) sites. At 12 months, beta-TCP bone area fraction (79.0%) was significantly greater than the control (42.5%). At 24 months, beta-TCP bone area fraction (86.5%) was significantly greater than IBB (55.6%) sites. Mean particle area fraction of beta-TCP sites decreased gradually until complete resorption at 24 months. IBB sites showed a significant decrease only between 3 (38.7%) and 6 (29.4%) months. DISCUSSION AND CONCLUSION: Complete bone healing was established in all grafted defects. IBB and beta-TCP are both excellent biocompatible materials. However, at 24 months beta-TCP particles were completely resorbed, whereas IBB particles still occupied a remarkable area fraction without significant resorption beyond 6 months. (More than 50 references.)

Alveolar Bone Loss↗