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Biomedical subjects

H Tal

Publications and source records attributed to H Tal.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1996

Clinical efficacy of a degradable film-forming product containing carbamide peroxide to reduce tooth discolouration.

The methods used to lighten tooth discolouration while conserving the tooth structure have attracted much attention in a society which places a high value on esthetics. The purpose of this article is to present a home bleaching agent that uses a film-forming preparation containing carbamide peroxide (CP) which, while degrading, serves as a slow release delivery system of the bleaching agent. The efficacy of the preparation containing 3% CP and 10% CP on reduction of tooth discolouration is evaluated by a Chromameter in a double-blind placebo-controlled study. The effect of the tested bleaching agent on the gingival status, plaque accumulation and pulp sensitivity is also assessed.

Adolescent↗
PubMed1994

Gingival hyperplasia induced by calcium channel blockers: mode of action.

Gingival hyperplasia is a known side effect in patients treated with diphenylhydantoin, cyclosporin and the calcium channel antagonists. The present study proposes a mechanism by which calcium channel antagonists may induce gingival hyperplasia. The calcium antagonist induces blockage of the aldosterone synthesis in zona glomerulosa of the adrenal cortex since this pathway is calcium-dependent, cyclic nucleotide-independent. This may produce a feedback stimulation of an increase in pituitary secretion of ACTH which affects zona glomerulosa hyperplasia. This hyperplasia is merely related by accumulation of steroid intermediate products (androgens) that are transformed to testosterone because of an increase in 17-alpha-hydroxylase enzyme activity. Elevated levels of testosterone may act on the gingival cells and matrix to produce gingival hyperplasia.

Adrenocorticotropic Hormone↗
PubMed1994

Inhibition of plaque formation by local application of a degradable controlled release system containing cetylpyridinium chloride.

The effect of a degradable controlled release system containing cetylpyridinium chloride (CPC) on plaque accumulation and gingivitis was evaluated when applied on the anterior teeth of volunteers (16-17 years) over 4 weeks. At baseline, plaque index (PI) and gingival index (GI) of the Ramfjord teeth were measured in the experimental and placebo groups, including 23 and 21 participants respectively. Following scaling and root planning, the participants were instructed to brush, using one brush stroke, the film-forming solution on the buccal surface of the maxillary and mandibular incisors, 1 x a day before bedtime. The applied active solution contained 9 mg of CPC (approximately 80 mg of 11% CPC solution), while the placebo solution was identical in formation, but without the active agent. After 4 weeks, in the CPC-applied group, the recorded PI scores were 0.52 (+/- 0.56) in the anterior area and 1.31 (+/- 0.80) in the posterior area, whereas the corresponding areas in the placebo group reached 1.25 (+/- 0.74) and 1.51 (+/- 1.00), respectively. The PI = 0 frequency in the buccal anterior surfaces after 4 weeks was 54.6% (+/- 38.7%) in the experimental group as compared with 21.9% (+/- 29.0%) in the placebo group (p = 0.005). In contrast to the anterior teeth, there was no significant difference between groups with respect to the PI scores in the non-applied posterior teeth. It may be postulated that the impressive 58% inhibition of plaque accumulation at the site of application is the result of an increase of the substantivity of the CPC due to its incorporation in the film-forming degradable controlled release system.

Administration, Topical↗
PubMed1994

Contiguous autogenous transplant--nineteen years' clinical and radiographic follow-up: a case report.

Contiguous autogenous transplant, also known as the bone-swaging procedure, is a technique aimed at regenerating lost periodontium. Clinical healing of bony defects after bone swaging has been satisfactory, but the relationship and mode of attachment between the bone graft and the root surface have not been fully investigated. A 19-year clinical and radiographic follow-up of a bony defect treated with the bone-swaging technique is presented. A significant coronal increase in bone height and a gain in clinical probing depth were achieved postsurgery and remained unchanged during the first 6 years. The long-term clinical and radiographic findings, however, indicated that the attachment developed at the root-bone interface may not have been a true attachment and may have been more vulnerable to pathogenic local agents. These observations may help the clinician to interpret the clinical and radiographic changes that occur in the area of a bony defect following the use of a bone graft.

Alveolar Bone Loss↗
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↗
PubMed1993

Histologic assessment of a contiguous autogenous transplant in a human intrabony defect. A case report.

Increased blood supply, vital bone marrow cells, and minimal mobility may play a significant role in the success of osseous grafts, and are characteristics of the bone swaging grafting technique. As in all autogenous grafts, the risk of disease transmission is minimal. Previous reports of clinical success raise questions as to the type of tissue response to this procedure. This case report examines 8 months radiographic and histologic results of a clinically successful bone swaging graft.

Adult↗
PubMed1993

The use of gingival autografts that contain submucosa in the repair of mucogingival defects in maxillary molars: case reports.

Many studies have shown that deep and wide gingival recessions can be predictably covered by free gingival autografts. Most of the autografts in these studies were performed on single-rooted teeth. This article presents a rationale for a new technique that repairs this type of defect in maxillary molar areas by means of thick masticatory mucosa autografts that intentionally include not only the lamina propria, but also portions of the submucosa. In addition, a new suturing approach that allows adequate adaptation of the donor tissue to the recipient site and permits relocation of the graft is proposed. This new approach has been shown to be a significant advantage in the anatomically problematic maxillary molar area.

Adipose Tissue↗
PubMed1993

Polarization microscopy of picrosirius red-stained collagen from oxodipine-induced hyperplastic gingiva of beagle dogs.

Using the model of oxodipine-induced gingival hyperplasia in beagle dogs, we investigated the collagen fibres of the hyperplastic gingiva by measuring the polarization colours from Picrosirius-red stained sections. The predominant polarization colours of the thick collagen fibres (1.6-2.4 microns diameter) of male oxodipine-treated dogs were greenish-yellow to yellow, while in controls and in female oxodipine-treated dogs, the same size fibres mostly appeared orange and red. These differences may be indicative of gender variation in the genesis of hyperplastic gingiva in calcium channel blocker treated dogs.

Animals↗
PubMed1992

The M20 IL-1 inhibitor prevents onset of adjuvant arthritis.

Cytokines, specifically IL-1 and TNF, have been implicated as important mediators of joint destruction in rheumatoid arthritis (RA). Elevated levels of IL-1 in the joint fluid of patients with RA have been reported, as well as the presence of IL-1 inhibitory activity. We have reported the characterization of an inhibitor derived from a myelomonocytic cell line cloned in our laboratory which is specific for IL-1. This IL-1 inhibitor is protein in nature which specifically inhibits activity in vitro and in vivo. Previous studies showed that the inhibitor reduced acute inflammatory reactions associated with IL-1 (fever, leukocytosis, local foot pad swelling, lymph node enlargement and acute phase reactants). Thus it was of interest to study whether the M20 IL-1 inhibitor could modify adjuvant-induced chronic inflammation in rats, which is often used as a model for human RA. Administration of complete Freund's adjuvant (CFA) into Lewis rats, resulted in a severe adjuvant arthritis (AA) which reached peak severity after 14 days. Daily administration of IL-1 inhibitor, beginning after injection of CFA, abolished the appearance of AA. The parameters investigated were: joint swelling (the increase in diameter of joints), peri-articular erythema, limping of the rats and histological examination. The effect of the M20 IL-1 inhibitor was shown to be dose dependent and the IL-1 inhibitor alone had no adverse effects. These results indicate that the M20 IL-1 inhibitor may have a role in the treatment of AA and may be used to reduce pathological processes in joint inflammation.

Animals↗
PubMed1992

Cryosurgical treatment of hemangiomas of the lip.

Removal of hemangiomas presents difficult management problems. This article describes the treatment of hemangiomas of the lip by cryosurgery and, in particular, evaluates the effectiveness of freezing in nitrous oxide cryosurgery on these lesions. Four women and two men, ages 40 to 76 years and manifesting angiomatous lesions on the vermillion of the lower or upper lips, were treated. Each site was directly exposed to two consecutive freeze-thaw cycles of 40 seconds freezing time at -30 degrees C to -40 degrees C. No anesthesia was required. Healing was uneventful. Superficial necrotic tissue covered the lesion at 1 week and necrotic slough was separated after 2 to 4 weeks, leaving a fully epithelialized surface. In all cases, there was no scarring and no recurrence was noted during the 2.5 year follow-up.

Adult↗
PubMed1992

Healing of experimental wounds in sialadenectomized rat.

The present study evaluates the healing of an experimental standardized full thickness excisional wound in the palate of a sialadenectomized rat model. Experimental rats underwent sialadenectomy of the submandibular and sublingual glands and ligation of the parotid ducts. A full thickness circular wound, 3 mm in diameter, was produced in the palate. Wound diameter was measured clinically and the area of inflammation and area of new connective tissue formation were determined histologically at 3, 7, 14, 21 and 28 days post-surgery. Wound diameter was similar in both the experimental and the control groups. The area of inflammation, however, was larger (p less than 0.05) in experimental rats at days 3, 7 and 14. New connective tissue formation was less (p less than 0.05) in sialadenectomized rats at days 14 and 21. The present results indicate that palatal wound healing is altered and delayed in sialadenectomized rats.

Animals↗
PubMed1992

Inhibition of plaque formation and gingivitis in beagle dogs by topical use of a degradable controlled-release system containing chlorhexidine.

The in vivo efficacy of a newly-developed dental application of a film-forming, chlorhexidine-containing system was examined in beagle dogs. A self-disintegrating film-forming solution was applied three times weekly to the dentitions of 7 out of 13 dogs, which were fed a soft-food diet. Plaque accumulation (Plaque Index) and gingival inflammation (Gingival Index) were recorded at one, two, four, six, and eight weeks. The local delivery of low-dose chlorhexidine to dogs significantly inhibited gingivitis and plaque formation. It is concluded that the dental application of a film-forming system may be a preferable method of periodontal disease prophylaxis, and may enhance supragingival plaque control in areas of isolated periodontal problems associated with obvious local predisposing factors.

Animals↗
PubMed1992

Formation of new periodontal attachment apparatus after experimental root isolation with collagen membranes in the dog.

This study evaluated the ability of collagen membranes to act as biodegradable barriers that interfere with colonization of the root surface by gingival cells and allow selective repopulation of the denuded root surface by periodontal ligament-derived tissue. Over a 3-year period, experimental and control surgical procedures were performed on canine teeth in six beagle dogs and on premolars in three beagle dogs. Results showed that the membranes partially prevented apical migration of epithelium during healing. Regeneration of new cementum, alveolar bone, and periodontal ligament-like tissue was found in the studied premolars but notably absent on the canines.

Animals↗