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Biomedical subjects

O Schwartz

Publications and source records attributed to O Schwartz.

At least 73 records · Page 4Linked to original sources
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

[Neutralising properties for HIV virus of hybrid protein MalE-CD4 expressed in E. coli and purified in 1 step].

Genetic fusions allowing the expression in E. coli of hybrid proteins between a bacterial periplasmic maltose binding protein (MalE) and the CD4 molecule (the receptor of the HIV virus) have been constructed. One of them has kept most of the properties of each constituent: it is exported, can be purified in one step on an affinity column, interacts with anti-MalE and anti-CD4 antibodies, binds HIV gp 120 protein and inactivates HIV virus in an in vitro test.

ATP-Binding Cassette Transporters↗
PubMed1988

Allotransplantation and autotransplantation of mature teeth in monkeys: the influence of endodontic treatment.

This study investigated the effect of endodontic treatment on root resorption of autotransplanted and allotransplanted mature teeth in unmatched monkeys. The material comprised 40 mature maxillary central incisors in 20 green Vervet monkeys (Cercopithecus aethiops). Teeth were either allotransplanted or autotransplanted in pairs of monkeys matched only for the size of the root. Endodontic treatment was performed at random peroperatively with gutta percha and Kerr sealer in 10 of each of the 20 autografts and 20 allografts. The extra-alveolar period was 18 minutes in all groups. Histometric analysis, which included registration of surface and inflammatory and replacement resorption (ankylosis), was done on serial sections of the grafts 8 weeks after transplantation. Endodontic treatment almost completely reduced inflammatory resorption in both allotransplanted and autotransplanted mature teeth (p less than 0.01). Peroperative endodontics elicited a small increase in ankylosis in autografts. In allografts, it unmasked a high amount of ankylosis, presumably primarily due to alloimmune reactions against the donor periodontal ligament, leaving only a small portion of normal ligament almost exclusively located along the cervical region of the root surface. Downgrowth of periodontal pocket epithelium was limited in all groups.

Animals↗
PubMed1988

A rapid and simple colorimetric test for the study of anti-HIV agents.

We report here the use of a simple, rapid, reproducible, and quantitative assay to detect the putative activity of anti-HIV agents. It can be employed with different T cell cultures, such as peripheral blood lymphocytes or CEM-C113 cells, a sensitive clone of CEM cells. It can be used alone as a rapid screening test in order to measure both cytotoxicity and the potential antiviral activity of large numbers of compounds. It can also be combined for thorough studies with other classic tests that detect virus production. Among these tests, a micro-method to measure reverse transcriptase activity is shown to be very useful. To illustrate the practicability of the assay, 3'-azido-2',3'-dideoxythymidine (AZT) and ribavirin are studied.

Antiviral Agents↗
PubMed1987

Allotransplantation of human teeth. A retrospective study of 73 transplantations over a period of 28 years.

An assessment was made of the postoperative fate of 73 allotransplanted human teeth carried out by 3 surgeons between 1956 and 1980 to determine the clinical and radiographical course of immunogenetically unmatched allotransplanted human teeth. The mean ages of recipients and donors were 34.1 and 15.2 years, respectively; 47 of the grafts had incomplete root-formation at time of transplantation. Mean observation period was 7.8 years with a maximum of 28 years. The study was terminated December 1985. The mean functional time of the grafts (function of graft without symptoms) was 6.8 years (max. 28.5 years). No signs of pulpal survival were found in any graft. Root resorption was found in 91.6% of grafts within a mean of 8.8 months after transplantation, causing a high frequency of graft loss within the first 2 years (34.1%). Recipients older than 45 years of age retained the grafts significantly longer than young patients. The major causes of graft loss were replacement (60.3%) and inflammatory resorption (24.4%). Graft loss due to marginal periodontitis was minor (2.7%). Inflammatory resorption, which was found more frequent in young recipients (P = 0.02), usually caused rapid rejection, whereas the survival time after ankylosis was significantly longer. In conclusion, no clinical or radiographical evidence of long-term survival of the pulpal or periodontal tissues of the unmatched allografts were found. However, despite a progressing replacement resorption frequently present, the allografts seem to function clinically sufficient, symptomless and often with clinically normal gingival condition for many years. Increasing age of the recipient at time of transplantation significantly increased the function time of the graft. Younger recipients showed more inflammatory resorption of the grafts.

Adolescent↗
PubMed1987

[Particles with retrovirus appearance and reverse transcriptase activity in cell cultures derived from lymph node biopsies in Hodgkin's disease].

Long term cultures of Reed-Sternberg like cells were obtained from lymph node biopsies of two patients suffering from Hodgkin's disease. As soon as the 15th day of culture, a weak magnesium-dependent reverse transcriptase activity was observed in the cell culture supernatants. Retroviral-like particles were observed in cell cultures as well as in their supernatants.

Adult↗
PubMed1987

Tooth transplantation to bone graft in cleft alveolus.

Autotransplantation of teeth has developed from a last resort operation into a well tested and relatively predictable clinical procedure. This article documents four cases where autologous teeth were successfully transplanted into bone from the iliac crest grafted to an alveolar cleft. The possibility of tooth transplantation should be considered when planning dental rehabilitation for patients with cleft.

Adolescent↗
PubMed1986

Autotransplantation of cryopreserved tooth in connection with orthodontic treatment.

In orthodontic treatment of certain cases of tooth loss, aplasia, or ectopia, autotransplantation is sometimes a valid treatment alternative and often provides an improved result, compared to conventional orthodontic treatment, if an appropriate donor tooth is available and the anatomic circumstances permit it. However, in some cases autotransplantation is not immediately possible as a one-step procedure. In such cases cryopreservation provides a clinically useful technique when an extraoral storage period of months or years is needed to orthodontically prepare the recipient region. In the present case a mature upper first left premolar was stored for 18 months. During this period sufficient space was achieved in the contralateral recipient region between the upper left first and second premolars. The thawed graft was autotransplanted to this position. Endodontic treatment was initiated 4 weeks after transplantation. Four years after transplantation, the periodontal healing of the grafted tooth appeared clinically and radiographically normal without any signs of root resorption. The presented case demonstrates the capacity of a cryopreserved tooth to regenerate what seems to be a normal periodontium after transplantation. If these findings are confirmed in further clinical trials, the technique could be a valuable tool in future orthodontic treatment planning.

Adult↗
PubMed1986

Cryopreservation as long-term storage of teeth for transplantation or replantation.

A method is presented which for the first time demonstrates the possibility of storing a human tooth over a period of 18 months in a frozen state with the periodontal membrane preserved viable, enabling the thawed tooth to heal with a normal periodontal ligament evaluated 2 years after autotransplantation. The cryopreservation technique included equilibration of the extracted tooth into 10% DMSO (dimethylsulphoxide) at room temperature in tissue culture medium including 10% human serum, freezing with a controlled rate of 1.2 degrees C/min to -40 degrees C and 6 degrees C/min to -100 degrees C, followed by transfer to and storage in liquid nitrogen at -196 degrees C. The tooth was thawed at a fast rate of approximately 100 degrees C/min, and DMSO was removed by slow equilibration at room temperature. A mature human bicuspid was autotransplanted after cryopreservation. Endodontic treatment was initiated 4 weeks after transplantation. 2 years after transplantation, the grafted tooth showed clinically and radiographically normal periodontal healing without signs of root resorption or marginal bone loss.

Adult↗
PubMed1986

Indications for surgical removal of supernumerary teeth in the premaxilla.

Usually supernumerary teeth in the maxilla are removed surgically, often due to retention of the permanent teeth in the region, but in certain cases the supernumerary teeth do not cause alterations in the eruption, position or integrity of the permanent dentition. This study was performed in order to review the indications for such surgical removal. The patient records of 208 patients with supernumerary teeth during the period of 1970-81 were reviewed retrospectively. Of these patients, 52 non-operated were furthermore examined clinically and radiographically in 1982; mean observation time 7.3 years (1-22 years). Results showed that none of the 52 non-operated patients had any symptoms or pathologic conditions related to the supernumerary teeth. In 37%, progressive resorption of the supernumerary teeth was seen, and in 24% the pericoronary space was markedly reduced compared to the first examination. The position and morphology was found to have influence on the prevalence of retention of the permanent incisors (p less than 0.0001). Widening of the pericoronary space during the observation period of the non-operated patients was not seen in any of the cases. Of the total of 262 teeth, 2 well-defined pericoronary cyst (pericoronary space greater than or equal to 5 mm) were found. From the present study, it is concluded that supernumerary teeth in the premaxilla may cause pathological conditions. However, each case must be considered individually concerning surgical treatment, and if no retention of permanent teeth or pathological conditions are present, observation with regularly radiographic controls is advisable. Enlarged pericoronary space (1-3 mm) does not alone seem to indicate surgical treatment.

Adolescent↗
PubMed1985

Cryopreservation before replantation of mature teeth in monkeys. (II). Effect of preincubation, different freezing and equilibration rates and endodontic treatment upon periodontal healing.

The effect of cryopreservation in liquid nitrogen at -196 degrees C for 1 week was studied by histometric analysis of 60 mature teeth replanted in 10 green Vervet monkeys. The effect of preincubation in enriched tissue culture medium was also investigated. 2 different freezing rates were compared, and the effect of stepwise equilibration of DMSO was studied as well as the effect of root canal treatment. The histometric analysis carried out 8 weeks after replantation revealed that if the cryoprotectant was equilibrated stepwise at room temperature, 10% DMSO had an even better cryoprotecting effect than previously shown by 5% DMSO equilibrated at 0 degree C. When this procedure was combined with a slow freezing rate of 0.3 degree C/min from -4 degrees C to -35 degrees C followed by plunging in liquid nitrogen, and supplemented by endodontic treatment before replantation, the amount of normal periodontal healing was almost similar to unfrozen and immediately replanted control teeth. Furthermore, this cryoprofile induced replacement resorption equal to the replanted control teeth. Preincubation in enriched medium for 24 h did not reduce resorption activity of the periodontal ligament. Endodontic treatment reduced the inflammatory resorption, demasking, however, hereby limited amount of ankylosis, that could be reduced by the above-mentioned cryoprofile. An optimal cryoprofile for mature teeth seemed to be slow equilibration at room temperature to a final concentration of 10% DMSO, slow freezing rates (0.3 degree C/min) and plunging in liquid nitrogen at -35 degrees C combined with fast thawing after storage at -196 degrees C, and followed by endodontic treatment after thawing.

Animals↗
PubMed1985

Autotransplantation of human teeth. A life-table analysis of prognostic factors.

In a retrospective study of a sample of 291 autotransplantations of human teeth carried out by 27 oral surgeons over a period of 25 years, the clinically and radiologically available factors at the time of surgery were analysed with reference to their prognostic relevance. Prognostically relevant factors related to loss of the transplanted teeth were determined by both univariate life-table analysis and multivariate Cox regression analysis. Of the 11 factors analysed in the Cox regression analysis, the following seemed to be prognostically relevant to loss or retention of the graft: developmental stage of the graft, age of the patient, donor tooth type, ectopia of the donor tooth, extraoral storage of the graft, and oral surgeon. In the present material, the prognosis of the grafts did not seem to be significantly influenced by such factors as prophylactic administration of antibiotics and fixation time. Using relevant parameters, it is possible to create a prognosis forecast for the individual patient. A case with a favourable set of parameters is shown.

Adolescent↗
PubMed1985

The effect of apicoectomy before replantation on periodontal and pulpal healing in teeth in monkeys.

The effect of resection of the apical part of the root before replantation upon periodontal and pulpal healing was studied in 7 green Vervet monkeys (Cercopithecus aethiops) using teeth with incomplete and complete root formation. Maxillary central incisors, mandibular lateral incisors and first and second mandibular molars were used in this experiment. On one side, the tooth was extracted and replanted with an intact root while the contralateral tooth had 2 mm of the apex resected for the purpose of facilitating pulpal repair and eliminating resorption in the resorption-prone region of the root. The replanted teeth were examined histologically 8 weeks after replantation. The histometric analysis revealed no significant difference in periodontal healing between teeth with or without apical resection. With regard to pulpal healing, apical resection was found to lead to significantly less vital pulp tissue in teeth with immature root formation. A similar, but not significant difference was found for mature teeth. Based on these findings, it could not be recommended that apices be resected prior to replantation in order to improve pulpal repair.

Animals↗
PubMed1985

Langerhans cells in candidal leukoplakia.

Using histochemical and immunohistochemical methods, we examined specimens of candidal leukoplakia from the oral mucosa of 5 smokers to determine the morphological relationships between Candida and Langerhans cells (LC) in tissue sections. LC were fairly evenly distributed in control sections, but had a patchy distribution in lesions. Fewer LC were found in lesions than in control tissue, but the difference was not statistically significant. Candidal antigens were not detected on LC by the methods used, but we found ATPase-positive LC among, or at least near, intraepithelial candidal hyphae. However, sections double-reacted with anti-Candida and T6 antibodies to label candidal antigens and LC, respectively, showed a clear zone of epithelium between the T6-positive LC and the candidal hyphae. The difference in distribution of ATPase-positive and T6-positive LC may indicate locations of 2 subtypes of LC, or a change in T6 antigen expression by the LC closest to the candidal hyphae.

Adult↗