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Biomedical subjects

H Tal

Publications and source records attributed to H Tal.

At least 55 records · Page 3Linked to original sources
PubMed1991

Healing of sites within the dog periodontal ligament after application of cold to the periodontal attachment apparatus.

The potential of periodontal ligament-derived tissues to regenerate periodontal attachment after cryosurgical trauma to the PDL in dogs was evaluated. The buccal alveolar plate of each canine tooth was exposed by a semi-lunar excision. A 3 mm thick cryoprobe, cooled to -81 degrees C, was placed on the bone 5 mm apical to the crest for 10 s. This induced cellular devitalization in the bone directly in contact with the probe and the PDL under it. The freezing-thawing cycle was repeated 3 times. Control sites were sham-operated at room temperature. Histologic sections from the center of the lesions were obtained from 1 h, 48 h and 30 d specimens. 1-h control and experimental histologic sections were similar. At 48 h post-surgery, the cellular component of the frozen PDL could not be identified and inflammatory response was minimal. The collagenous framework, however, appeared to form a continuum between the alveolar bone and cementum. Lacunae in the bone at the frozen segment were empty. The injured PDL was surrounded by normal PDL. Control specimens appeared normal. At 30 d, the PDL space in the frozen segments was populated by PDL-like tissue which did not differ significantly from the PDL coronal or apical to it. Collagen fibers appeared to be attached to the cementum on one side and to the alveolar bone on the other. Bone resorption or ankylosis was not observed in the experimental sites. It is suggested that the extracellular matrix in the devitalized area was preserved, supporting regeneration of the cryolesion.

Alveolar Process↗
PubMed1991

Spontaneous ameloblastic fibro-odontoma in a female mouse.

A spontaneous ameloblastic fibro-odontoma is described in a 73-wk-old female mouse. The tumor was located in the molar mandibular region. The diagnosis was made on the basis of the histologic presence of odontogenic epithelial tissue embedded in mesodermal tissue resembling dental papilla, and containing in addition dentin and enamel. The positive reaction for keratin and vimentin confirmed the presence of ectodermal and mesodermal elements respectively in the tumor.

Animals↗
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↗
PubMed1991

Salivary gland cysts of the oral cavity: clinical observation and surgical management.

Mucoceles are common cystic lesions of the oral mucosa. Extravasation mucoceles are mainly found in the lower lip of young patients, whereas retention mucoceles are usually located in the cheek or palate of older patients. The disparate site and age incidences of extravasation and retention mucoceles suggest that these two types are not related and have different pathogenesis. Treatment modalities for mucoceles are reviewed, with special attention to the cryosurgical technique for the treatment of oral ranulas.

Adolescent↗
PubMed1990

Estimation of dental plaque levels and gingival inflammation using a simple oral rinse technique.

A simple, non-invasive test (the Oratest) has recently been proposed, which provides an estimate of oral microbial levels based on the rate of oxygen depletion in expectorated milk samples. Following 30 seconds of vigorous rinsing with sterilized milk, 3 ml of the expectorate is added to a test tube containing the redox indicator, methylene blue, and the time required for a color change from blue (i.e., aerobic conditions) to white (anaerobic conditions) at the bottom of the test tube is recorded. In the present study, Oratest scores were compared to clinical parameters (Plaque Index [PI] and Gingival Index [GI]) in a group of 49 volunteers. Significant correlations were found between the logarithm of Oratest results and PI (r = -0.58; P = 0.001) as well as GI (r = -0.66; P = 0.001). The data indicate that the Oratest provides a reliable estimate of gingival inflammation, thus extending the previously reported strong correlations between Oratest scores and microbial counts. The data suggest that the Oratest may have potential as a clinical and research tool.

Adult↗
PubMed1989

Peripheral giant cell granuloma during orthodontic treatment.

Inflammatory and hyperplastic gingival responses during orthodontic treatment are common. These may complicate the actual treatment and may require periodontal therapy. The present report describes the development of an interproximal enlarged peripheral giant cell granuloma during orthodontic treatment, resulting in migration and separation of the neighboring teeth and resorption of the interproximal alveolar septum and molar root. The lesion was excised and the bone was curetted; this led to spontaneous migration of the involved teeth to their natural positions.

Child↗
PubMed1989

Periodontal response to long-term abuse of the gingival attachment by supracrestal amalgam restorations.

The combined length of the supracrestal connective tissue attachment and the junctional epithelium is referred to as the "biologic width". The long-term (1-year) effect of complete violation of the supracrestal connective tissue attachment was examined in beagle dogs. Full thickness periodontal flaps were elevated, exposing the buccal bony crests of the maxillary and mandibular canines of 3 beagle dogs. The roots of the experimental teeth were planed and class V cavities were prepared. The apical border of each cavity was located at the alveolar bone crest. The cavities were restored with amalgam and the flaps were repositioned and sutured. In the control sites, a notch was prepared at the CEJ and the distance between the notch and the bony crest was measured. The dogs were sacrificed 57 weeks after the operation and the experimental and control sites prepared for histologic analysis. Every 5th section was examined and measurements were taken of the amount of gingival and bone recession, the length of the connective tissue and the epithelial attachment. Control sites healed uneventfully. Gingival recession averaged only 0.5 mm; bone loss was minimal and averaged 0.15 mm. The combined length of the supracrestal connective tissue and epithelial attachment measured 4.47 mm. In experimental sites, the gingiva receded 3.16 mm on average. Moderate bone loss (mean = 1.17 mm) was noted, but no signs of bone resorption were seen at the time of sacrifice. After bone loss, root surfaces which were previously attached to alveolar bone by periodontal ligament were mainly (0.90 mm) attached to connective tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolar Process↗
PubMed1989

Reduction of dental plaque formation by chlorhexidine dihydrochloride lozenges.

The effect of chlorhexidine dihydrochloride (chlorhex HCl) in lozenges on plaque growth was assessed on 21 subjects with fresh plaque of 7 days duration. The lozenges, which contained 5 mg chlorhex HCl, were sucked three times daily after meals, for 2 weeks. The study was a single-blind crossover. Placebo lozenges had all the ingredients except chlorhex HCl. These were used as a control. Results indicated that lozenges containing chlorhex HCl were a potent plaque inhibitor. The mean plaque score was reduced by 62.8% from an initial mean plaque score (DO) of 2.38 +/- 0.48 to (D7) 0.89 +/- 0.26 (p less than 0.0001), after 1 wk of usage. A further reduction to plaque score (D14) of 0.56 +/- 0.27 (p less than 0.0001) was recorded by the end of the 2nd wk. Usage of the placebo during the same time period did not show significant differences in the plaque score (DO = 2.38; D7 = 2.33; D14 = 2.42). Inhibition of plaque formation to the 1104 test surfaces revealed a total elimination of the higher levels of plaque (scores 4 and 5), a considerable reduction of the middle levels (scores 2 and 3) and a significant increase (44.7%) of low level plaque (score 1). Total elimination of plaque (score 0) was observed in 50.3% of the test group surfaces. Lozenges containing 5 mg chlorhexidine dihydrochloride, taken three times daily, were an efficient, comfortable and potent agent for reducing and inhibiting plaque formation. These lozenges are a more convenient alternative to chlorhexidine mouthrinses and may prove to be superior to these.

Adolescent↗
PubMed1989

Collagen membranes prevent apical migration of epithelium and support new connective tissue attachment during periodontal wound healing in dogs.

The capacity of collagen membranes to prevent the apical migration of epithelium and to support new connective tissue attachment was assessed in experimental periodontal defects in dogs. Experimental periodontal defects were produced in 8 mongrel dogs by removing the alveolar bone and the periodontal ligament over the most coronal 5 mm of the labial aspect of the maxillary canines. Experimental defects associated with the right canine and its surrounding bone were covered by collagen membranes prepared by air drying gels of rat type I fibrillar collagen. Flaps were repositioned and sutured. The contralateral control defects were sham-operated without using collagen membranes. Animals were killed, 10 and 30 days after surgery, 4 at each time point. The experimental and control sites were processed for histologic and histomorphometric evaluation. At 10 d, the average distance between the apical margin of the epithelium and the apical level of the defect (EA) sites was 3.20 +/- 0.55 mm for the experimental sites and 0.73 +/- 0.18 mm for the controls. The experimental root surfaces apical to the epithelium and the collagen membranes were covered by connective tissue cells. At 30 d, the EA for experimental and control sites were 2.55 +/- 0.36 mm and 0.47 +/- 0.30 mm, respectively. In the experimental sites healing by long junctional epithelium was observed in the coronal 40% of apico-occlusal dimension of the defect and new connective tissue attachment with inserting fibers in the apical 55% of the defect length. No new bone formation was observed. In the control sites, pocket formation was found in the most coronal one-third of the defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Scanning electron microscope evaluation of wear of stainless steel and high carbon steel curettes.

Root planing depends on quality instrument cutting edges. The sharpness and wear of stainless steel (SS) and high carbon steel (HCS) dental curettes were compared before and after standardized root planing procedures. Forty working edges of dental curettes, 20 of each alloy, were examined by scanning electron microscope (SEM) prior to any root planing (control), after 15 strokes, and after 45 strokes. Root planing was carried out on freshly extracted, single-rooted teeth, mounted in natural positions in mannikin jaws. Working areas measuring 3 x 5 mm were marked on root surfaces previously exposed by periodontitis. Each working edge was examined at points 1 mm and 2 mm from the tip under the same magnification (x 240). Microscopic observations showed that edge deformation increased from the control (factory sharpened) group, to the "15 stroke" group, and from the "15" to the "45 stroke" group, in both SS and HCS curettes. SS curettes, however, demonstrated significantly more wear than HCS curettes. After 45 strokes, only 5% of the SS curettes were sharp, compared to 20% of the HCS curettes. While 65% of the SS curettes showed severe edge deformation by the end of the study, only 20% of the HCS curettes were severely deformed (P less than 0.01). The results indicate that HCS curettes are more resistant to wear than SS curettes. Further study is indicated to evaluate the relationship between actual bevel dimensions and root planing effectiveness.

Alloys↗
PubMed1989

Access to the rat mandibular molars: a facial surgical approach.

A surgical technique enabling convenient access to the rat molars and their supporting tissues is described. The masseter, the body of the mandible and the alveolar process supporting the molars are exposed via a skin incision, parallel to and immediately in front of the anterior border of the masseter. Denudation of the alveolar process from attached soft tissues permits easy and accurate access to the periodontium of the molars; moreover, separation of the gingival attachment from the tooth cervix exposes the oral cavity and permits convenient and accurate access to the molars. Post-surgical healing is uneventful. The method is easy and convenient, and should prove useful for experimental studies.

Animals↗
PubMed1988

Correction of mucosal defects of periapical origin with periodontal surgical techniques.

Periapical lesions usually heal after successful root canal therapy. Persistent apical-oral communications may be due to anatomic and pathologic features that were originally linked to the endodontic cause of the lesion. One such factor is close proximity of the root apex to the oral mucosa. These defects necessitate corrective surgical intervention similar to techniques used in periodontal surgery. Four cases involving young female patients are described. These defects occurred in teeth that did not complete their maturation before necrosis of the pulp set in.

Adolescent↗
PubMed1988

Forced eruption combined with gingival fiberotomy. A technique for clinical crown lengthening.

A new approach to clinical crown lengthening has been developed and described. The technique combines controlled eruptive tooth movement and incision of the supracrestal gingival attachment. The procedure was performed in patients with severe destruction of a tooth crown and in whom clinical crown lengthening procedures were essential before the teeth could be properly restored. Controlled eruptive forces were activated by simple orthodontic appliances. During the active phase of forced eruption, repeated intrasulcular incisions through the junctional epithelium and the supracrestal connective tissue attachment were performed. The technique prevented coronal displacement of the gingiva and the attachment apparatus during the orthodontic extrusion, thus overcoming the need for corrective osseous surgery.

Adolescent↗
PubMed1988

Partial regeneration of periodontal tissues using collagen barriers. Initial observations in the canine.

The capacity of collagen membranes to support guided regeneration of periodontal tissues in the dog was assessed. The mesiolabial, labial and distolabial aspects of the mesial root of the second and third mandibular premolar were surgically exposed in three beagle dogs. Collagen membranes, 0.5 to 0.7 mm thick, prepared from a purified solution of rat-Type I collagen were interposed between the gingival flap and the exposed root surfaces of the right premolars. The left premolars were sham-operated without the use of collagen membranes. Animals were killed one month after surgery. Tissue blocks, including the surgical sites, were removed and prepared for histological and histometric examination. Long epithelial attachment was the modality of healing in the control sites. The apical level of the junctional epithelium was located either at, or close to, the apical level of the defect. The experimental sites exhibited a combination of three healing modalities: (1) partial regeneration of periodontal tissues (new bone, periodontal ligament and cementum) occurred in the apical half of the defect, (2) long epithelial attachment developed in the coronal quarter of the defect and (3) connective tissue adhesion developed between the two. Pocket depth was similar in both the control and experimental sites. Collagen membranes could not be identified at the time of examination. The results indicate that: (1) collagen membranes have the capacity to support regeneration of periodontal tissues and (2) collagen membranes are either incorporated within the healing tissues or degraded by these during the healing process. These findings suggest that collagen membranes may be of value in reconstructive periodontal therapy.

Alveolar Process↗
PubMed1988

Facial radicular groove in a maxillary central incisor. A case report.

A facial radicular groove may occur in central maxillary incisors and act as a funnel for accumulating plaque and calculus. Since it is inaccessible to routine oral hygiene efforts of the patient and to treatment manipulations of the dentist, this anomaly predisposes the tooth to localized periodontal disease. Conservative or surgical treatment of such teeth should restore periodontal health by creating an environment more favorable for plaque control.

Adult↗