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Biomedical subjects

M Groisman

Publications and source records attributed to M Groisman.

12 recordsLinked to original sources
PubMed1999

Histomorphometric analyses of hydroxyapatite-coated and uncoated titanium dental implants in rabbit cortical bone.

In this article, we report the results of analyses of bone healing around four types of dental implants. Five implants of each type were inserted into the proximal tibia metaphysis of adult New Zealand rabbits and were analyzed using computerized histomorphometry 12 weeks after implantation. Hydroxyapatite-coated implants showed more direct bone contact and more lamellar bone in the threads than the titanium implants. There was a significant correlation between an increase in the percentage of mineralized tissue in the threads of metallic implants and cellular density around the implant, indicating less lamellar bone in contact with metallic implants.

Alveolar Process↗
PubMed1990

Clinical and histological findings in ligature-induced experimental periodontitis in dogs. A pilot study.

Prior to experimental periodontal regenerative procedures in animals, the process of destruction due to periodontitis is often simulated by placing ligatures around the necks of teeth. 2 models, one using cotton floss ligatures and the other elastic rubber ligatures, have been widely used. The aim of this study was to compare these 2 methods using clinical and histometric criteria. Premolars on both sides of the mandibular jaw were used in 2 beagle dogs. Periodontal tissue breakdown was induced during a 48-day period using cotton floss ligatures on one side of the mandible and contra-laterally by elastic rubber ligatures. At weekly intervals, the ligatures were changed and pocket depth and loss of probing attachment were recorded. All the ligatures were removed after 7 weeks. The animals were fed a soft, plaque-promoting diet during the experimental period. 20 days after ligature removal, the teeth were hemisected and the 2 roots extracted. From each tooth, 1 root was prepared for scanning electron microscopy and one for light microscopy. At the time of extraction, no differences regarding pocket depth or probing attachment level were found between the 2 groups. Root resorption was observed in all elastic ligature teeth, whereas only minor alterations at the root surface were observed on cotton ligature teeth. This finding may be of particular interest to investigators designing studies evaluating the healing sequalae of regenerative surgery in animals. As was observed in this study, root resorption can already be present in the pre-experimental phase of periodontal tissue breakdown, particularly if elastic ligatures are used.

Animals↗
PubMed1990

Transmission electron microscopy of supra-alveolar periodontal healing of auto- and allotransplanted teeth in monkeys.

An ultrastructural study of the supra-alveolar periodontal healing of auto- and allotransplanted teeth was performed in 4 immunologically unmatched green Vervet monkeys. Eight mature incisors were either auto- or allotransplanted. Non-transplanted adjacent incisors served as controls. Prior to transplantation the teeth were endodontically treated extraorally. Eight weeks after transplantation, biopsies including part of the tooth and the adjacent supra-alveolar tissues were taken, fixed, decalcified and processed for electron microscopy. A thin electron dense layer covered the root surface of the autotransplanted teeth. Most collagen fibres inserted into this electron-dense border, as well as into the underlying cementum. A similar relationship between the fibres and root surface was found in controls. On the allotransplanted teeth a layer of electron-dense granular material covered the root surface in the supra-alveolar area. Collagen fibres inserting into the electron-dense border were frequently observed. Fibroblasts were the predominant cell type in the connective tissue adjacent to all transplanted teeth. In autotransplants 2 morphotypes of fibroblasts were observed: 1) cells with dilated endoplasmic reticulum and swollen mitochondria; and 2) cells with normal characteristics of protein synthesis and secretion. The fibroblasts of the allografts were predominantly cells with dilated endoplasmic reticulum and swollen mitochondria. The results indicated some similarities in the healing between the root surface and connective tissue in the supra-alveolar portion of the roots of auto- and allotransplanted teeth.

Animals↗
PubMed1989

Supra-alveolar periodontal healing of auto- and allotransplanted teeth in monkeys.

Although intra-alveolar healing of allotransplanted teeth often shows pathological changes due to rejection of the tooth graft, previous clinical findings seem to indicate that the supra-alveolar part of the allografts heals differently, which is of significant prognostic value. The aim of the present study was to determine the healing of the cervical part of the periodontium of auto- and allotransplanted mature teeth in monkeys. In 4 adult, immunologically unmatched, green vervet monkeys 16 mature permanent maxillary and mandibular incisors were extracted, endodontically treated and either auto- or allotransplanted; 8 untreated neighbouring incisors served as controls. Block biopsies including part of the tooth and the adjacent vestibular tissues were obtained after a healing period of 8 weeks. The biopsies were decalcified in EDTA and embedded in Epon. In semi-thin section (1.5 microns) the morphology of the supra-alveolar periodontal tissues was analysed in the light microscope. The orientation of the connective tissue fibres close to the root surface was found to be more parallel to the root surface of allotransplants compared with autografts, while in the control teeth the fibres were generally oriented perpendicular to the root surface. Resorption of the root was seldom found in the supra-alveolar portions of any of the transplanted teeth. The junctional epithelium had migrated slightly apically onto the root surfaces of allotransplanted teeth. The gingival connective tissue adjacent to allotransplanted teeth showed a significantly increased number of lymphocytes compared with autografts and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1989

Dental health knowledge in a group of Latin American refugees in Sweden.

Sixty-nine Latin American refugees with a mean age of 31 years participated in this study. The knowledge about dental health before and after reading a self-instructional manual in Spanish was tested by questionnaires. The test persons were also interviewed about their dietary habits. The results showed an improvement of 30% of right answers after reading the manual and that a frequent sugar consumption was common. This indicates that a self-instructional manual can be of value in oral health prevention in a similar group of non-resident immigrants.

Adult↗
PubMedDate not supplied

Clinical evaluation of hydroxyapatite-coated single-tooth implants: a 5-year retrospective study.

The use of implants to replace missing single teeth has become a valuable treatment option. This study presents a 5-year retrospective clinical analysis of single teeth replaced with hydroxyapatite-coated implants. Of the 271 cylinder and screw implants placed over this period, 12 were lost (survival rate = 95.57%). In addition to aesthetic compromise, the most frequent complication was loosening of the abutment screw. These results corroborate findings from the literature and suggest that the described procedure can be safely performed in daily restorative procedures.

Adolescent↗