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Biomedical subjects

O Moses

Publications and source records attributed to O Moses.

At least 19 recordsLinked to original sources
PubMed2004

In vitro effects of enamel matrix proteins on rat bone marrow cells and gingival fibroblasts.

Emdogain (EMD), a formulation of Enamel Matrix Proteins (EMP), is used clinically for periodontal regeneration, where it stimulates cementum formation and promotes gingival healing. In this study, we investigated the in vitro effects of EMD on rat bone marrow stromal cells (BMSC) and gingival fibroblasts (GF). EMD (at 25 micro g/mL) increased the osteogenic capacity of bone marrow, as evidenced by approximately three-fold increase in BMSC cell number and approximately two-fold increase in alkaline phosphatase (ALP) activity and mineralized nodule formation. The presence of EMD in the initial stages (first 48 hrs) of the culture was crucial for this effect. In contrast, EMD did not induce osteoblastic differentiation of GF (evidenced by lack of mineralization or ALP activity) but increased up to two-fold both their number and the amount of matrix produced. These in vitro data on BMSC and GF could explain the promotive effect of EMD on bone formation and connective tissue regeneration, respectively.

Alkaline Phosphatase↗
PubMed2001

Tetracycline modulates collagen membrane degradation in vitro.

BACKGROUND: Structural integrity of implanted bioabsorbable barrier membranes should be preserved for a sufficient time to ensure expected results. Collagen membranes are degraded by metalloproteinases (MMP). Their degradation rate can be altered either by enhancing structural integrity or by delaying the degradation process using MMP inhibitors. Tetracyclines (TTC) present inhibitory effects on matrix MMP. Immersing membranes in TTC solution before implantation can delay their degradation. The purpose of the present study was to evaluate the effect of collagen membranes immersed in varying TTC concentration solutions on the rate of their degradation in vitro. METHODS: Collagen bioabsorbable membranes were prepared as 5 mm diameter membrane discs. Membranes were then incubated at 4 degrees C for 24 hours, in either phosphate buffered saline (PBS, Ca2+ and Mg2+ free) or with TTC-HCl dissolved in PBS concentrations of 5 mg/ml, 50 mg/ml or 100 mg/ml. After rinsing, membranes were incubated with either bacterial collagenase or cultures of human bone lineage cells. Membrane degradation was studied on days 2, 4, 7, and 14. Two- and 3-way analysis of variance was used to analyze results. RESULTS: Samples supplemented with bacterial collagenase exhibited a statistically significant interaction between changes of free protein in the medium, antibiotic concentration used for the immersion, presence of collagenase in the medium, and incubation time (P<0.0001). Membranes incubated with bone cells exhibited similar degradation trends. CONCLUSIONS: Collagen membranes immersed in 50 mg/ml TTC solution exhibited the longest degradation time, both in the clostridial collagenase and the human bone cell lineage assays. Immersion in a 50 mg/ml TTC solution before implantation will delay their degradation.

Absorbable Implants↗
PubMed2001

Preprosthetic clinical crown lengthening procedures in the anterior maxilla.

Clinical crown lengthening procedures (CCLP) are used to enhance aesthetics and/or provide adequate tooth structure for placement and retention of a restoration while respecting the attachment apparatus. When restoration margins extend beyond the biologic width, inflammation and anatomic changes can develop. Anterior CCLP are indicated to increase the labial exposure of the clinical crown and/or the sound tooth structure coronal to the bone crest. Preservation of the interproximal papillae is mandatory to obtain desirable final results in the aesthetic region. This article illustrates various methods of CCLP used to achieve successful oral rehabilitation in the anterior maxilla.

Crown Lengthening↗
PubMed2000

Rotated palatal flap in immediate implant procedures. Clinical evaluation of 26 consecutive cases.

Immediate implant placement after tooth extraction is a successful treatment modality. Primary flap closure is important for satisfactory final results in these procedures. The purpose of this article was to evaluate a surgical approach that would enable predictable primary soft tissue closure over implants placed into fresh extraction sockets. In 24 patients, 26 consecutive implants were placed immediately following extraction of one anterior or premolar maxillary tooth. Primary closure was achieved by a surgical technique based on a rotated palatal flap (RPF), covering the implant. Deproteinized bovine bone was used as grafting material. The apicocoronal distance between the buccal alveolar crestal bone and the coronal aspect of the implant body was measured at time of implant placement (mean 2.6 mm, SD 1.72) and at second stage surgery (mean 0.6 mm, SD 0.70). The difference between both records was calculated. The mean gain in crestal bone was 2.0 mm (SD 1.69, P < 0.001). In 1 patient, where the implant cover screw became exposed early, crestal bone loss was noted. This technique offers a predictable valuable treatment approach to achieve and maintain primary soft tissue coverage and crestal bone regeneration over implants immediately placed within a bony envelope, after extracting maxillary teeth, without the use of barrier membranes.

Adult↗
PubMed2000

Interproximal papillae reconstruction in maxillary implants.

BACKGROUND: Gingival esthetics has become an important factor in the overall success of most maxillary implant-supported restorations. Periodontal plastic surgery procedures may be used to enhance esthetics in the maxillary anterior region. The purpose of the present study was to evaluate a new surgical approach, performed at implant exposure, to reconstruct interdental papillae around maxillary implant-supported restorations. METHODS: The surgical procedure was performed on 32 patients, in which 36 consecutive single tooth osseointegrated implants were exposed in the anterior and premolar maxillary region. Previous to implant exposure and 6 months postoperatively, once the implant-supported restoration was in place, mesial and distal papilla contour measurements were calculated, based on a modification of the papillary index score (PIS). Statistical analysis consisted of paired t test, Pearson's correlation, and ANOVA with repeated measures. RESULTS: Preoperative PIS ranged from 0 to 3 and from 1 to 3 at the 6 months follow-up control. A mean of mesial and distal papilla, within the same tooth, was used for paired t test statistical analysis. A mean increase of 1.07 (SD 0.43) in PIS was statistically significant (P<0.001). At the second measurement, in no site was PIS smaller (0%) while in 64 sites PIS was higher (89%). In 51 papilla (71%) there was an increase of 1 PIS unit and 13 (18%) of 2 PIS units between both measurements. CONCLUSIONS: The presented surgical technique performed at second stage implant surgery was useful for partial or total interproximal papilla reconstruction adjacent to maxillary single-implant restorations.

Analysis of Variance↗
PubMed1999

Rotated split palatal flap for soft tissue primary coverage over extraction sites with immediate implant placement. Description of the surgical procedure and clinical results.

Immediate implant placement after tooth extraction is becoming a common procedure in implant-supported oral rehabilitation. However, lack of primary full flap closure can jeopardize final results. A surgical approach that would enable predictable primary soft tissue closure over implants placed into fresh extraction sockets is described and evaluated. This technique is based on a rotated deep split thickness palatal flap (RSPF) containing periosteum and connective tissue, covering the implant and/or a barrier membrane. In 29 patients, 33 consecutive implants were placed immediately post extraction of 1 or 2 anterior or premolar maxillary teeth. Patients were divided in 2 groups: Group A (15 patients; n = 18 sites) where no barrier membrane was used and Group B (14 patients, n = 15 sites) where an occlusive resorbable collagen membrane was used. Distance between the alveolar crestal bone and the coronal aspect of the implant was measured at time of implant placement (Group A: mean 1.9 mm, SD 1.16; Group B: mean 4.6 mm, SD 1.18) and at second stage surgery (Group A: mean 0.3 mm, SD 0.46; Group B: mean 0. 7 mm, SD 0. 7). The difference between both records (crestal bone formation) was calculated (Group A: 1.7 mm, SD 1.03; Group B: 3.9 mm, SD 1.12) and found to be statistically significant (P <0.0001). Crestal bone formation, relative to the initial bone crest-implant distance at time of implant placement was approximately 85% in both groups. In 4 sites (2 in each group), where the cover screws were exposed before second stage surgery, complete crestal bone regeneration did not occur. Use of a barrier membrane may be obviated in appropriate cases while placing implants into fresh extraction sites. This procedure offers a predictable treatment approach in achieving complete soft tissue coverage, while allowing for healing of bony defects in immediate implantation procedures.

Adult↗
PubMed1999

Immediate loading of modular transitional implants: a histologic and histomorphometric study in dogs.

Modular Transitional Implants (MTI) are made from pure titanium and are used to support fixed provisional restorations during the osseointegration of definitive implants. This study histologically examined the jaw response to loaded MTIs in the dog mandible. Three implants were inserted transmucosally into each side of the mandible in 3 dogs. Stability was examined using a Periotest. Anterior and posterior implants were splinted using a cemented acrylic resin fixed partial denture to allow immediate loading. The middle implant remained unloaded and was used as a control. Dogs were sacrificed 11 to 12 weeks after implantation, and tissue blocks containing the implants were removed. Histologic examination showed that 10 of the 18 implants had good bone-to-implant contact, with the percentage of bone contacting the threaded portion of the implant varying from 30% to 65%. There was no statistical difference (p > 0.1) in percentage of bone-to-metal contact between loaded and unloaded implants. Six implants were entirely surrounded by connective tissue with or without inflammation; two implants were lost during the study. The success rate did not differ between loaded and unloaded implants. In the successful implants trabecular bone made good contact with the implant, forming supporting struts. There was bone remodeling in some bone-to-metal contact areas. It is believed that success was mainly influenced by the initial bone density at the implant site and by the uncontrolled load that the animals applied to the implants during the early healing stage.

Animals↗
PubMed1997

Bone regeneration around an osseointegrated implant. A simultaneous approach in a fenestrated defect: a case report.

The use of a barrier membrane, with or without osseous allograft, has been shown to establish regeneration of osseous tissue around dental implants. Following three episodes of persistent symptomatic failed apicoectomy and subsequent tooth extraction, an osseointegrated implant was placed in a wide fenestrated defect. Demineralized freeze-dried bone allograft was covered by an occlusive expanded polytetrafluorethylene membrane. The reentry procedure revealed complete bone fill that followed the texture of the augmentation material beyond the previous buccal bony envelope.

Adult↗
PubMed1997

Preimplant guided bone regeneration in the anterior maxilla.

Guided bone regeneration is a clinical procedure aimed at promoting bone formation at sites where there is severe bone loss. The purpose of this article was to demonstrate reconstruction of deformations of the alveolar process resulting from traumatic injuries to maxillary incisor teeth by guided bone regeneration procedures followed by insertion of dental implants. In both cases, submembranous space-making was stabilized by human demineralized freeze-dried bone. Implant insertion at the sites of bone augmentation resulted in successful restorations. Histologic examination of biopsy samples from the submembranous hard tissue revealed particles of demineralized freeze-dried bone allografts partially surrounded by uninflamed connective tissue and by vital bone adjacent and adhered to the demineralized freeze-dried bone allograft particles.

Adolescent↗
PubMed1996

Collagen gel and membrane in guided tissue regeneration in periodontal fenestration defects in dogs.

The effect of a collagen gel matrix as a submembranous space-maintaining material was evaluated in guided tissue regeneration procedures. In 4 dogs, contralateral surgical circular fenestration defects, 5 mm in diameter, were produced at the midbuccal aspect of the alveolar bone in 8 maxillary canines. Removal of bone, PDL and cementum was complete. Experimental sites were filled with collagen gel and covered with collagen membranes; control sites were covered with collagen membranes and the underlying space was spontaneously filled with blood. Mucogingival flaps were repositioned. Histological and histomorphometric observations, 6 weeks post-surgery, indicated that defects covered by collagen membranes presented the most impressive regeneration with almost complete coverage of the denuded root by new cementum (98.4%) and new bone (63.2%). In the experimental defects, 83.5% coverage of new cementum with only 21.9% new bone regeneration was observed. These results suggest that collagen gel, interfered with healing by PDL and bone-derived cells in the submembranous space.

Alveolar Bone Loss↗
PubMed1995

Juvenile periodontitis: microbiology and the therapy approach.

Juvenile periodontitis is an inflammatory disease of the periodontium, characterized by rapid destruction of the periodontal tissues around more than one tooth in the permanent dentition. These lesions progress rapidly after onset, but tend to slow with time. The age of onset is circumpubertal, usually manifesting in a localized form around the incisors and first molars, although some generalized cases have been reported. Clinically, there is often a small amount of supragingival plaque and calculus that is not commensurate with the amount of destruction present. In addition to a unique bacterial flora, a genetic influence and an altered host response have also been demonstrated as etiologic factors. This article discusses subgingival microflora, the host response, the host-parasite interaction in juvenile periodontitis and the outcome of the treatment plan.

Adolescent↗
PubMed1993

Mucosal considerations for osseointegrated implants.

Tissue resistance is determined by the nature of cells and intercellular contacts irrespective of the presence or absence of keratinization, masticatory mucosa, or skin. However, these tissues are more easily maintained and less vulnerable to inflammation when in contact with dental implants. Lack of masticatory mucosa and the presence of alveolar mucosa embracing the implant are often associated with plaque, which can induce inflammation resulting in subsequent peri-implant destruction. To facilitate proper mechanical oral hygiene maintenance, transplantation of autogenous masticatory mucosal grafts at the implant sites was performed in patients without attached gingiva, unfavorable vestibulum with submucosal muscular activity, and uncontrolled peri-implant mucositis. The rationale for having attached mucosa around osseointegrated implants and illustration of possible methods of mucosal management in the different phases of implant rehabilitation are presented.

Dental Implantation, Endosseous↗
PubMed1992

The management of soft tissue defects using the "gingival shaving" technique.

A simple, effective technique is described for the correction of unfavourable gingival contour during post-surgical or pre-prosthetic procedures. Termed the "gingival shaving technique", it is conducted with high-speed course diamond burs. Results are relatively rapid and predictable, especially in cases where esthetics are most desirable. The technique can be performed by the periodontist or prosthodontist, and can be repeated until satisfactory gingival contour is achieved. Case selection, careful preparation, and post treatment management and care are essential for success.

Dental High-Speed Technique↗
PubMed1991

A comparison of panoramic radiography with computed tomography in the planning of implant surgery.

The accuracy of panoramic radiography and computed tomography (CT) in the evaluation of depth of the mandible at recipient implant sites was compared by measuring the distance between the edentulous bony crest and the superior border of the inferior alveolar canal in a group of ten patients. Distortion was calculated using the metal ball technique for the panoramic radiographs and the computer scale for the CT scans. The precise distance between the bony crest and inferior alveolar canal was determined from postoperative radiographs from the known length of the implants. It was found that although CT scans are more precise, panoramic radiography is sufficiently accurate for routine clinical purposes. CT scans have, however, an additional advantage in presurgical planning, since they reveal the horizontal dimension and shape of the mandible, and the topography and buccolingual location of the inferior alveolar canal.

Alveolar Process↗
PubMed1991

Heparan sulfate and fibronectin improve the capacity of collagen barriers to prevent apical migration of the junctional epithelium.

The objective of the present study was to assess the effect of bilayered/collagen barriers enriched with fibronectin and heparan sulfate on the prevention of apical migration of the epithelium during the initial stage of periodontal wound healing. Experimental osseous defects were produced on the labial aspect of maxillary canines in dogs. Experimental sites were treated with either bilayered enriched collagen barriers or with non-enriched bilayered collagen barriers, using the guided tissue regeneration technique. Control sites were treated with monolayered collagen barriers that were not enriched with fibronectin and heparan sulfate. Histologic and histomorphometric examinations performed on specimens obtained 20 days post-operative indicate the formation of a short junctional epithelium in the experimental sites treated with enriched collagen barriers. In this group, 95% of the occlusal-apical length of the defects was repopulated by connective tissue cells. In the other 2 groups, a long junctional epithelium developed with only 65% of the occlusal-apical length of the defects being repopulated by connective tissue cells. These findings suggest that the enrichment of collagen barriers with fibronectin and heparan sulfate may be important to enhance the repopulation of exposed root surfaces by connective tissue cells and prevent the apical migration of the epithelium during the initial stages of periodontal wound healing.

Alveolar Process↗
PubMedDate not supplied

Healing of dehiscence defects at delayed-immediate implant sites primarily closed by a rotated palatal flap following extraction.

In 21 patients, 28 maxillary teeth were extracted because of periapical or periodontal infection, root fracture, or untreatable caries. A rotated palatal flap procedure was used to achieve primary soft tissue closure over extraction sites. At 5 to 7 weeks postextraction, 28 implants were placed. Buccal dehiscence-type defects were treated with guided bone regeneration procedures using bovine bone mineral and resorbable collagen membranes. Mean defect area at the time of implant placement (23.7 mm2, SD 11.49) was significantly reduced at uncovering (0.7 mm2, SD 0.99). The mean percentage of defect reduction (clinical bone fill) was 97% (SD 4.26). Implants placed in compromised sites shortly postextraction according to the presented 2-stage protocol gave good short-term clinical results.

Adult↗