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Biomedical subjects

Micha Peled

Publications and source records attributed to Micha Peled.

31 records · Page 2Linked to original sources
PubMed2003

Association of metalloproteinases, tissue inhibitors of matrix metalloproteinases, and proteoglycans with development, aging, and osteoarthritis processes in mouse temporomandibular joint.

The temporomandibular joint (TMJ) is an important growth and articulation center in the craniofacial complex. In aging it develops spontaneous degenerative osteoarthritic (OA) lesions. Metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPS) play key roles in extracellular matrix remodeling and degradation. Gelatinase activities and immunohistochemical localization of MMP-2, -3, -8, -9, and -13 and TIMP-1 and -2 were examined in mandibular condyle cartilage of neonatal mice up to 18 months old. The most intense immunostaining for all enzymes and TIMPs and the peak of gelatinase activities were found in animals in the stages of early growth (1 week to 3 months) followed by a decrease during maturation and aging. However, clusters of positively immunoreactive chondrocytes were detected in cartilages of old animals displaying OA lesions. Positive safranin-O staining, indicative of sulfated proteoglycans (PGs), was prominent in the TMJ of newborn mice up to 3 months old followed by reduction during maturation and aging, except in regions displaying OA lesions. Temporal codistribution of PGs, MMPs, and TIMPs during skeletal maturation reflected an active growth phase, whereas their reduction coincided with the more quiescent articulating and maintenance phase in the joint cartilage. Osteoarthritic lesions were associated with both increased PG synthesis and MMP immunoreactivity, indicating limited repair activity during initial stages of osteoarthritis.

Aging↗
PubMed2003

Reduction of viable bacteria in dentinal tubules treated with clindamycin or tetracycline.

AIM: We sought to evaluate and compare the antibacterial effect of clindamycin and tetracycline in bovine dentinal tubules. METHODS: Dentinal tubules of 32 cylindrical bovine root specimens were infected with Streptococcus sanguis N1. Clindamycin 2% or tetracycline 2% (Ledermix) was placed in the root canal for 1 week. Powder dentin samples obtained from within the canal lumina by using International Standards Organization No. 25 to No. 31 burs were examined for the presence of vital bacteria after the brain-heart infusion plates were inoculated and the colony-forming units were counted. The potent effect of the medicaments was also evaluated through the use of the agar diffusion test. RESULTS: Heavy bacterial infection was observed in the control bovine root specimens at the layer close to the lumen. This decreased rapidly from layer to layer up to the deepest layer tested (300-400 microm), which contained several hundred colony-forming units. Clindamycin significantly reduced the amount of viable bacteria in each dentin layer compared with the positive control and tetracycline (P <.01). The agar diffusion test, wherein dilutions in increments of 1/3 and 1/9 were used, revealed that both medicaments had antibacterial activity, but clindamycin was significantly better. In the 1/27 dilution, clindamycin had a minor effect and tetracycline had no effect at all. CONCLUSION: Under the experimental conditions used in this study, the commercial preparations of clindamycin were more effective than those of tetracycline (Ledermix) in the agar diffusion test and clindamycin penetrated into dentinal tubules up to 400 microm. Thus, it has the potential to serve as an effective intracanal medicament in persistent infections when other medicaments fail.

Analysis of Variance↗
PubMed2003

Dental implants in patients with type 2 diabetes mellitus: a clinical study.

PURPOSE: Systemic factors, such as diabetes mellitus, can influence the success rate of dental implants. The authors describe their experience using the MIS implant system (Medical Implant System, Shlomi, Israel) for retention of overdentures in patients with type 2 diabetes mellitus and provide data regarding the level of satisfaction of the patients, the improvement of function, mucosal and periimplant health, and bone level around implants in this group. METHODS: The study group consisted of 41 patients with type 2 diabetes mellitus who received 141 implants for retention of overdentures. RESULTS: The success rate was 97.3% and 94.4% 1 and 5 years following implantation, respectively. The majority of patients reported improvement of function following the new treatment. A high correlation was observed between mucosal health and improvement of function. No correlation was found between failed implants and glucose level. CONCLUSION: The clinical outcome of dental implants in a selected group of patients with well-controlled type 2 diabetes mellitus is satisfying and encouraging. Further investigations and clinical trials over a longer period of time are needed to determine the long-term survival of implants in diverse groups of patients with diabetes mellitus.

Aged↗
PubMed2003

Common oral manifestations during pregnancy: a review.

UNLABELLED: Pregnancy has far-reaching systemic effects extending beyond the reproductive system. Oral and masticatory changes during pregnancy have been documented for many years; however, their magnitude and frequency have not been stressed. This review highlights the major oral complications during pregnancy. Pregnancy gingivitis and pregnancy tumor are described and presented, and possible preventive strategies are suggested. TARGET AUDIENCE: Obstetricians & Gynecologists, Family Physicians. LEARNING OBJECTIVES: After completion of this article, the reader will be able to summarize the major oral complications during pregnancy, to outline the etiologic factors associated with each of these conditions, and to explain the role of dental treatment during pregnancy.

Dental Care↗
PubMed2003

Guided tissue regeneration in smokers: effect of aggressive anti-infective therapy in Class II furcation defects.

BACKGROUND: Guided tissue regeneration (GTR) using membrane barriers is still the reconstructive treatment of choice for a variety of periodontal defects. Smokers, however, present a reduced regenerative response to GTR. The purpose of the present study was to design and examine a new protocol with emphasis on anti-infective therapy for patients who are cigarette smokers and who require GTR procedures for the treatment of Class II furcation defects. METHODS: Chronic periodontitis patients who were smokers and who exhibited mandibular Class II furcations were initially pooled for further assessment. Patients were randomly assigned to either the experimental group (EG) or a control group (CG). Clinical measurements and indices were recorded at baseline and at 6, 9, and 12 months, and included: plaque assessment index; gingival assessment index; probing depth; and probing attachment level (vertical [PAL-V] and horizontal [PAL-H]) using a prefabricated acrylic stent as a reproducible reference point. All patients underwent hygienic phase periodontal therapy. Next, GTR was performed, and the furcation dimensions (height, width, and depth) were measured. A membrane was placed, and a 25% metronidazole gel was then applied over the outer surface of the membrane (EG only) and the flaps repositioned so that the membrane was completely submerged. Instructions included twice daily rinses with chlorhexidine gluconate 0.2% for 1 week (CG) or as long as the membrane was in place (EG), doxycycline 100 mg x 1/day for 1 week (CG) or 6 to 8 weeks (EG), and ibuprofen 3 x 400 mg/day for 7 days. Patients were initially seen for prophylaxis weekly (EG) or biweekly (CG). Metronidazole was applied to the free gingival margins and/or over the exposed membrane at every prophylactic visit (EG). Six to 8 weeks after surgery, the membrane was removed surgically, and the amount of new tissue growth (NTG) from the cemento-enamel junction (CEJ) to the most coronal extension of the new tissue was recorded. Following membrane retrieval, patients were seen for prophylaxis and oral hygiene reinforcement every month (EG) or quarterly (CG). At 12 months postoperatively, the area was surgically reentered and the surgical measurements repeated. RESULTS: Thirty-eight subjects, 21 females and 17 males, aged 35 to 61 were accepted in this study. Baseline clinical parameters were similar for both groups. One year postoperatively, there was no statistically significant difference in probing depth reduction or in horizontal PAL between EG and CG, but vertical PAL gain was significantly greater in EG. As for alveolar parameters 1 year postoperatively, the mid CEJ-crest distance and furcation width decreased in EG but increased in CG. A similar trend was observed for furcation height. Furcation depth reduction in both groups was similar. A comparison between new tissue growth at retrieval and eventual bone formation 1 year postoperatively demonstrated a smaller change in EG patients compared to CG patients, which was statistically significant for both the distal and the mid-tooth area, as well as for the tooth mean. CONCLUSIONS: While smoking prevented tissue maturation and mineralization, the anti-infective protocol enhanced these processes, resulting in a more favorable outcome. It is therefore suggested that when GTR is performed for Class II furcation defects in smokers, anti-infective therapy should be incorporated into the treatment protocol to enhance the regenerative outcome in these patients.

Adult↗
PubMed2003

[Application of Ilizarov method in maxillofacial treatment].

Distraction osteogenesis is becoming the treatment of choice for the surgical correction of hypoplasias of the maxillofacial skeleton. The mandible can be elongated by intraoral or extraoral devices. The intraoral devices are smaller, do not leave an external scar and do not cause social inconvenience to the patient. The main disadvantages are less control of vector and the need for a second operation for removal. The most important factors of mandibular distraction are planning of distraction, location of the osteotomy, control of vector of lengthening and type of distraction device. In the maxilla, our experience with three types of maxillary distraction is discussed: 1) the rigid extraoral distraction, 2) the surgically assisted protraction and 3) the intraoral method. In the last years, distraction osteogenesis was applied in the treatment of obstructive sleep apnea. The method has several advantages over other methods, mainly in treatment of young children in order to improve airway and to decannulate tracheostomy. Alveolar distraction osteogenesis poses a new challenge in reconstructing atrophic alveolar bone with no need to harvest bone graft or to use bone substitutes. The advantages and problematic issues of alveolar distraction such as vector control of distraction are described. The intraoral method should always be considered first. However, in severely hypoplastic patients, when three-dimensional correction is necessary, the extraoral device has an advantage over the intraoral device. In the future, the issues to consider will be improvement of osteotomies by endoscopy, development of smaller multidirectional devices, improvement of bone quality by cytokines and growth factors in order to shorten the time of device bearing by the patients.

Facial Bones↗
PubMed2002

Characterization of midface maxillary membranous bone formation during distraction osteogenesis.

The purpose of the study was to follow the early events in bone formation and neovascularization during maxillary distraction and after the consolidation period and to define the characterization of the new bone in the distracted area. Maxillary osteotomy was performed in seven sheep. In five animals, an external distraction device was used for maxillary lengthening of 20 mm at a rate of 1 mm/day for 20 days. Another two animals served as controls without distraction. Sequential biopsies were performed. The methods used for analysis were histologic, immunohistochemical, and ultrastructural by transmission electron microscopy. During the 5 days of latency, a fibrin clot was formed that after 5 days of distraction was replaced by granulation tissue, proliferating mesenchyme-like cells, and capillaries. After 10 days of distraction, the regenerated tissue could be divided into three main zones and two transitional areas: a central zone occupied by many polygonal mesenchyme-like cells and spindle-shaped cells that proliferated intensively; two paracentral zones on both sides of the central zone in which many cells showed morphologic signs of apoptosis leading to a decreased number of fibroblast-like cells embedded in wavy collagen fibers; a transitional area from the central to the paracentral zone in which concentric cellular colonies were believed to represent a novel form of vasculogenesis; distal-proximal zones, located on both sides of the paracentral zones and in continuation with the old bone, showed delicate new woven bone trabeculae that grew continuously in the direction of lengthening and gradually became mineralized; and a transitional area from the paracentral to the distal-proximal zones in which there was recruitment of preosteoblasts from the distracted tissue to the trabecular tips. These further differentiated into osteoblasts that contributed to the trabecular growth. The histologic feature pattern was similar after 15 and 20 days of continuous distraction. At the end of lengthening, after 20 days, delicate longitudinally oriented trabeculae continued to grow by recruiting preosteogenic cells from the central distracted tissue, became mineralized, and were rimmed by osteoblasts. After 6 weeks of retention, the trabeculae thickened and consisted of a mixture of lamellar and woven bone. In conclusion, the distraction force creates a pool of undifferentiated mesenchyme-like cells with osteogenic potential and triggers capillary formation, a clear zonation can be observed during active lengthening, and new bone trabeculae begin to form between 5 and 10 days after distraction, soon become aligned with osteoblasts, and continue to grow as long as distraction force is applied. This characterization may help in any exogenous involvement with growth factors to improve bone quality.

Animals↗
PubMed2002

Frey syndrome--delayed clinical onset: a case report.

Frey syndrome is a disorder characterized by unilateral sweating and flushing of the facial skin in the area of the parotid gland occurring during meals. The syndrome is a sequela of parotidectomy and may follow other surgical, traumatic, and inflammatory injuries of the parotid and submandibular glands and the cervical and upper thoracic portions of the sympathetic trunk. Pathogenesis is based on regeneration of sectioned parasympathetic fibers with inappropriate innervation of cutaneous sweat glands. Various studies have reported the clinical incidence of Frey syndrome after parotidectomy to be as high as 53%. The reported incidence of Frey syndrome in patients not undergoing intraoperative preventive measures is 96% in patients evaluated by means of an iodine-starch test 12 months postoperatively. We present a case in which a patient developed symptoms of Frey syndrome 8(1/2) years after superficial parotidectomy. Although most patients with Frey syndrome have only mild-to-moderate symptoms (only 6% of patients experience severe symptoms), the potential for appearance of Frey syndrome years after the parotidectomy must be discussed with the patient before surgery in the parotid region.

Adenoma, Pleomorphic↗
PubMed2002

Fracture of dental implants: literature review and report of a case.

Fracture of dental implants is a rare phenomenon with severe clinical results. In this article, the literature is reviewed and various causative factors that may lead to fracture are presented. Galvanic activity has not been mentioned before as a possible cause for implant fracture, yet, it can occur at the level of contact with the superstructure. This is illustrated by the case of a titanium implant restored with a non-precious porcelain-fused-to-metal cemented crown that fractured 4 years after loading. The radiographs show alveolar bone resorption around the fixture. Metallurgical analysis of the implant indicated that the fracture was caused by metal fatigue and that the crown metal, a nickel-chromium-molybdenum alloy, exhibited corrosion. These findings suggest a new explanation for implant fractures; cytotoxic nickel ions, leaching from the base metal alloy may cause bone resorption. This in turn leads to increased mobility, facilitating washout of the luting cement. Contact of the base metal with titanium in the presence of oral fluids produces galvanic currents that hasten corrosion and leaching out of nickel ions, thus leading to further bone resorption. Loss of bone support allows lateral bending moments that cause metal fatigue, eventually leading to fracture. Therefore, good treatment planning and appropriate case selection might have prevented this fracture. Furthermore, the use of nonprecious metal alloy for the crown's infrastructure had further contribution to the chain of events that led to the implant's fracture.

Aged↗
PubMed2002

Concomitant focal fibrocartilaginous dysplasia of the tibia and eosinophilic granuloma of the jaw in a child.

This 2-year-old child presented with concomitant eosinophilic granuloma of the lower jaw and focal fibrocartilaginous dysplasia of the right tibia. Her eosinophilic granuloma was diagnosed on the basis of the clinical picture, imaging studies and the characteristic histologic appearance. Focal fibrocartilaginous dysplasia was revealed incidentally during the eosinophilic granuloma staging process. After chemotherapy, all signs of eosinophilic granuloma subsided, but focal fibrocartilaginous dysplasia remained without signs of clinical or radiographic progression. The importance of differentiating these two conditions is stressed in order to avoid ineffective and inappropriate treatment of focal fibrocartilaginous dysplasia.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2002

Periodontal changes in liver cirrhosis and post-transplantation patients. II: radiographic findings:.

BACKGROUND: Liver disease and transplantation affect bone turnover. The role of cylosporin A (CsA) in aggravating bone loss is controversial. The aim of the present study was to examine the effect of liver cirrhosis, transplantation, and immunosuppressive therapy with either CsA or tacrolimus on alveolar bone height. METHODS: The experimental group consisted of 13 liver cirrhosis (LC) patients. A second experimental group included 24 post-liver transplantation patients (PT) receiving CsA or tacrolimus. Seventeen healthy subjects formed a control group. Panoramic x-rays were taken and digitized using a computer-based measurement software to assess alveolar bone height of all available teeth. RESULTS: Bone loss in the PT group (4.57+/-0.56 mm) was significantly higher than the control (C) (2.73+/-0.38 mm); however, it was significantly lower (P = 0.0005) than the LC (6.47+/-0.75 mm). Likewise, alveolar bone loss showed a trend for negative correlation (R = 0.404, P = 0.06) with the duration of immunosuppressive therapy post-liver transplantation. CONCLUSIONS: Liver cirrhosis patients demonstrated greater bone loss compared to healthy controls. Restoration of liver functions following transplantation seems to have the potential to reverse some of these radiographic changes. Further longitudinal studies will be necessary to substantiate these findings.

Alveolar Bone Loss↗
PubMedDate not supplied

Analysis of postoperative symptoms following surgical endodontic treatment.

OBJECTIVE: The purpose of this prospective study was to analyze postoperative pain and swelling of patients undergoing surgical endodontic treatment using a strict protocol incorporating measures to control postoperative symptoms. METHOD AND MATERIALS: The study consisted of 82 patients referred for surgical endodontic treatment. All surgical procedures were performed using a microsurgical technique employing strict protocol. All patients were premedicated with a single dose of oral dexamethasone (8 mg) preoperatively and two single doses (4 mg) 1 and 2 days postoperatively. Antibiotics were prescribed selectively only when severe symptoms were present due to infection. Patients were administered chlorhexidine mouthwash twice daily starting 3 days before the operation and an additional 7 days postoperatively starting the day after surgery. Cold compresses were applied on the skin at the site of surgery intermittently every 15 minutes during the operative day. Pain and swelling were recorded pre- and postoperatively, and the influence of different variables on postoperative sequelae were analyzed. RESULTS: One day postoperatively, 76.4% of the patients were completely pain free, less than 4% had moderate pain, and 64.7% did not report any swelling. The preoperative symptoms significantly influenced the pain experience post-surgery. CONCLUSION: There was a low incidence of postoperative pain and swelling following endodontic surgical treatment according to protocol with measures to control postoperative signs and symptoms. Patients with preoperative pain were more likely to have postoperative pain.

Administration, Oral↗