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Biomedical subjects

S Friedman

Publications and source records attributed to S Friedman.

At least 235 records · Page 13Linked to original sources
PubMed1991

Leakage after lateral condensation with finger spreaders and D-11-T spreaders.

The purpose of the study was to determine the leakage after lateral condensation with the use of finger spreaders and D-11-T spreaders. Fifty root canals were instrumented, and laterally condensed with gutta-percha and Grossman's cement. In 20 canals finger spreaders were used for the condensation and in a further 20 canals D-11-T spreaders were used. After 24 h in 100% humidity, the roots were painted with nail polish except for their apical 2 mm, which remained exposed. Five canals were not obturated (negative control) and five canals were obturated and the apices sealed with sticky wax (positive control). The expressed root tips were suspended in 2% methylene blue dye for 48 h. The teeth were then split longitudinally and the apical leakage measured and compared for each group. The results obtained by the positive and negative control teeth confirmed the effectiveness of the methodology used. Average dye penetration for the finger spreaders was statistically significantly less than for the D-11-T spreaders. Dye penetration of more than 0.5 mm occurred in 6 roots for the finger spreaders and in 12 roots for the D-11-T spreaders.

Dental Leakage↗
PubMed1991

Relation of pre- and intraoperative factors to prognosis of posterior apical surgery.

The relation of preoperative and intraoperative factors to the prognosis of apical surgery was studied in 136 premolar and molar roots. The evaluated factors were: clinical signs and symptoms, size of the periapical lesion, root canal obturation, tooth restoration, apical retrofilling, and the operating surgeon. A significantly higher success rate was found in roots obturated 2 mm or shorter of the apex, in roots without post restoration, and after retrofilling of roots with apparently well-condensed obturation. The prognosis differed significantly following treatment by various operators but was unrelated to their experience.

Apicoectomy↗
PubMed1991

pH variation among materials used for intracoronal bleaching.

Intracoronal bleaching of pulpless teeth with 30% hydrogen peroxide may result in external cervical root resorption. One of several suggested etiological factors associated with this complication is the pH of the bleaching materials. Because the available data on the pH values of bleaching materials were conflicting, it was the purpose of this study to measure the pH of the materials commonly used for bleaching pulpless teeth. The pH of different concentrations of sodium perborate and 30% hydrogen peroxide, alone or in combination, were measured for a period of 14 days. Sodium perborate was confirmed to be alkaline, whereas 30% hydrogen peroxide was acidic. The pH of the materials when mixed together gradually changed from acidic to alkaline as the concentration of sodium perborate was increased. A thick clinical consistency mixture of both materials was alkaline, and its alkalinity increased with time. These results do not support the theory relating bleaching-induced root resorption to an acidic pH of the bleaching pastes.

Borates↗
PubMed1991

Dye leakage in retrofilled dog teeth and its correlation with radiographic healing.

In a previous study in beagle dogs, statistically significant differences in healing were observed radiographically 6 months after apicoectomy and retrofilling with amalgam and varnish, glass ionomer cement, or a composite resin. The purpose of this study was to compare the leakage of these retrofilling materials and to correlate leakage data with healing. After the dogs were sacrificed, 48 roots were extracted. Half of the roots had been irradiated with a CO2 laser on the bevelled root surface after retrofilling. The roots were coated with nail polish, except for their bevelled surface, and were suspended together with positive and negative controls in 2% methylene blue for 8 h. After the specimens were longitudinally split, they were ranked according to the severity of dye penetration, as observed with a dissecting microscope. The differences in dye leakage among the three retrofilling materials were not statistically significant. Consequently, dye leakage did not correlate with the previously assessed healing. Dye penetrated into the root through the bevelled root surface, regardless of CO2 laser exposure of that surface.

Animals↗
PubMed1991

Histological characterization of bleaching-induced external root resorption in dogs.

External root resorption occasionally develops after intracoronal bleaching with hydrogen peroxide. In this study, an experimental model was established to study thermocatalytic bleaching-induced root resorption in dogs. Histological examination after 6 months revealed that 18% of the teeth had root resorption lesions. The lesions could be divided into three types. In type I, root excavations were associated with a dense inflammatory cell infiltrate. Type II lesions were characterized by granulation tissue formation. In type III, the lesions were filled with reparative cementum. The three types probably represent different phases of one process. Calcium hydroxide had no effect on the occurrence or type of resorption. The instability of hydrogen peroxide and the presence of inflammatory resorption lesions 6 months postoperatively suggest hydrogen peroxide-induced toxic radicals or denaturants as potential irritants.

Animals↗
PubMed1991

Treatment results of apical surgery in premolar and molar teeth.

The purpose of this investigation was to study long-term treatment results following apical surgery in premolars and molars. These results were assessed by reexamination of 136 roots on which apical surgery was performed. The observation period varied from 6 months to 8 yr. According to radiographic and clinical criteria, the treatment results were considered successful in 44.1% of the roots, doubtful in 22.8%, and unsuccessful in 33.1%. Clinical signs and symptoms were associated with 33.1% of the roots, occurring significantly more in roots demonstrating radiographically unsatisfactory healing. The results are discussed with reference to other studies on apical surgery in posterior and anterior teeth. However, methodological differences do not permit the drawing of direct comparisons to those studies.

Adolescent↗
PubMed1991

Nutritional dwarfing: a growth abnormality associated with reduced erythrocyte Na+,K(+)-ATPase activity.

To assess whether nonorganic nutritional dwarfing (ND) is accompanied by a biochemical adaptation to reduced nutrient intake, Na+,K(+)-ATPase activity of erythrocytes was examined. The study included 27 children with ND who demonstrated deteriorating linear growth and poor weight gain (caused by self-imposed dietary restrictions), 20 patients who initially exhibited ND growth patterns and subsequently experienced catch-up weight gain and growth after nutritional rehabilitation (NDR), and 32 normally growing children who had familial short stature and/or constitutional growth delay (F/CSS). Na+,K(+)-ATPase activity in erythrocytes was significantly lower in ND patients than in the NDR and F/CSS groups. Furthermore, Na+,K(+)-ATPase activity was positively correlated with incremental body weight gain. Na+,K(+)-ATPase concentrations did not differ significantly with regard to sex, chronological age, bone age, or pubertal status. These data suggest that the growth retardation of ND patients is associated with decreased erythrocyte Na+,K(+)-ATPase activity without other biochemical evidence of malnutrition.

Adolescent↗
PubMed1991

In vivo efficacy of various retrofills and of CO2 laser in apical surgery.

The purpose of the present study was to radiographically assess the efficacy of various retrofilling materials and of the use of CO2 laser in apical surgery. The mandibular premolars of six beagle dogs were infected, resulting in periapical lesions. Apical surgery was performed without root canal treatment. Amalgam with cavity varnish, glass ionomer cement and a lightcured composite resin were the retrofilling materials used. In half of the material CO2 laser was used on the root surface and the bone, for occlusion of the dentinal tubuli and sterilization. The healing following surgery was observed radiographically for six months. The highest success rate (89%) was found in the roots retrofilled with amalgam and varnish, and the lowest (60%) in those retrofilled with the composite resin. The difference between these groups was statistically significant. The success rate following retrofilling with glass ionomer cement was 69%, and was not significantly different from both the other groups. Under the conditions of this study, the use of CO2 laser during surgery did not affect the treatment results.

Animals↗
PubMed1991

Retrograde approaches in endodontic therapy.

The routine use of retrograde fillings during apical surgery, as well as the material of choice for that purpose, have been debated. A retrograde filling is placed so as to seal an infected root canal causing periapical pathosis. Therefore, retrograde root canal fillings should be performed routinely during apical surgery regardless of the apparent technical quality of the root canal obturation, unless orthograde endodontic treatment is performed in conjunction with surgery. When orthograde treatment is not performed, retrograde root canal filling enhances the prognosis of apical surgery. An array of potential retrograde filling materials have been extensively investigated in vitro and in vivo. Once that the biocompatibility of the materials is confirmed a clinical comparison, rather than in vitro sealability studies, is the most valid evaluation method. Some of the difficulties encountered in long term clinical studies in patients may be avoided in animal studies. The review of the relevant literature of the past decade suggests that amalgam used in conjunction with cavity varnish is the retrograde filling material of choice. It must be stressed, however, that retrograde filling is not comparable to debridement and obturation of the entire root canal. Therefore, when the only way to approach the root canal is from the apical direction, rather than placing an apical retrograde filling, a retrograde endodontic treatment of the entire canal should be preferred, if it is feasible.

Apicoectomy↗
PubMed1991

In vitro efficacy of sodium perborate preparations used for intracoronal bleaching of discolored non-vital teeth.

Bleaching materials containing 30% hydrogen peroxide have been used successfully for the treatment of discolored non-vital teeth. Intracoronal application of these materials was occasionally associated with the development of external root resorption. Extracted human teeth with intact crowns were discolored in vitro and bleached with three preparations of sodium perborate. These preparations included: sodium perborate with 30% hydrogen peroxide, sodium perborate with 3% hydrogen peroxide and sodium perborate with water. The bleaching materials were placed in the pulp chamber of the discolored teeth and sealed with IRM for 14 days. They were replaced with fresh preparations after 3 and 7 days. The coronal tooth shades were evaluated after 3, 7 and 14 days and a comparison of the bleaching success of the groups was made at each interval. It was found that after 14 days and three bleachings there was no significant difference in success between the groups. It is therefore recommended that sodium perborate be used in combination with water rather than with hydrogen peroxide to reduce the risk of post-bleaching external root resorption.

Borates↗
PubMed1991

Ofloxacin during the second trimester of pregnancy.

Ofloxacin can cause retarded ossification and arthropathy in young animals, but there is no published information about its teratogenicity in humans. A 36-year-old woman was treated with ofloxacin 200 mg bid for 6 days during the 19th week of gestation. Ultrasound follow-up of the measurements and structure of the fetal long bones revealed no abnormalities. The neonate's physical examination and X-rays of the chest and long bones were normal. Although no teratogenic or toxic effects were observed in this patient, the use of ofloxacin in human pregnancy should only be a clinical consideration until sufficient evidence regarding its safety in the human fetus has been published.

Adult↗
PubMed1991

Gestational diabetes mellitus. A survey of perinatal complications in the 1980s.

Neonatal morbidity was assessed in the offspring of 878 mothers with gestational diabetes mellitus (GDM), 132 mothers with pre-GDM, and 380 control subjects. Compared with the control group, the GDM group had a higher incidence of complications, including macrosomia, hypoglycemia, hyperbilirubinemia, hypocalcemia, polycythemia, and major congenital anomalies (P less than 0.05). Although our GDM patients were stringently managed with diet or diet plus insulin, as indicated, and maintained almost euglycemic values, these neonatal complications could not be eliminated. Our data may be consistent with observations published during the last decade that even subtle degrees of maternal hyperglycemia can have a detrimental effect on perinatal outcome. Most neonatal complications readily respond to therapy if diagnosed and treated early and promptly. Macrosomia can have a detrimental effect on delivery (trauma) and later long-term implications during childhood. Tight metabolic control with diet and, when indicated, insulin treatment may be advantageous in reducing fetal birth weight. Criteria of how tight the metabolic control should be remain to be accurately defined.

Diabetes, Gestational↗
PubMed1991

Bullosis diabeticorum. A report of two cases with a review of the literature.

Bullosis diabeticorum is a rare complication of long-standing diabetes mellitus. Bullous lesions, which appear like burn-induced blisters, occur suddenly without trauma in the feet. These bullae heal spontaneously without scarring; however, recurrence is common. The etiology of bullosis diabeticorum remains unknown. Several theories exist as to causal and contributory factors related to this cutaneous manifestation of diabetes mellitus.

Aged↗
PubMed1991

Micromanipulation in a center for reproductive medicine.

Several variations of micromanipulation of the female gamete (zona drilling, zona cracking, ooplasmic sperm injection, partial zona dissection) have been applied recently to human IVF to overcome severe male factor. Of the first 16 cycles attempted using partial zona dissection, one pregnancy resulted leading to a normal term delivery. Careful removal of the coronal cells, as well as stepwise removal of sucrose postpartial zona dissection, will facilitate this procedure and greatly reduce potential damage to the oocyte by pH, mechanical, or thermal injury. Micromanipulation has become a routine service offered in our program in cases where the likelihood of a poor IVF outcome is either known or suspected, and also serves as a replacement for simple reinsemination in cases of failed fertilization.

Adult↗
PubMed1990

Direct photolabeling of the EcoRII methyltransferase with S-adenosyl-L-methionine.

Ultraviolet irradiation of EcoRII methyltransferase in the presence of its substrate, S-adenosyl-L-methionine (AdoMet), results in the formation of a stable enzyme-substrate adduct. This adduct can be demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after irradiation of the enzyme in the presence of either [methyl-3H]AdoMet or [35S]AdoMet. The extent of photolabeling is low. Under optimal conditions, 4.5 pmol of [3H]AdoMet is incorporated into 100 pmol of enzyme. Use of the 8-azido derivative of AdoMet as the photolabeling substrate increases the incorporation by approximately 2-fold. However, this adduct, unlike the one formed with AdoMet, is not stable when treated with thiol reagents or precipitated with trichloroacetic acid. A catalytically active conformation of the enzyme is needed for AdoMet photolabeling. Heat-inactivated enzyme or proteins for which AdoMet is not a substrate or cofactor do not undergo adduct formation. Two other methyltransferases, MspI and dam methylases are also shown to form adducts with AdoMet upon UV irradiation. The binding constant of the EcoRII methyltransferase for AdoMet determined with the photolabeling reaction is 11 microM, which is similar to the binding constant of 9 microM previously reported (Friedman, S. (1986) Nucleic Acids Res. 14, 4543-4556). The AdoMet analogs S-adenosyl-L-homocysteine (Ki = 0.83 microM) and sinefungin (Ki = 4.3 microM) are effective inhibitors of photolabeling, whereas S-adenosyl-D-homocysteine (Ki = 46 microM) is a poor inhibitor. These experiments indicate that AdoMet becomes covalently bound at the AdoMet-binding site on the enzyme molecule. The EcoRII methyltransferase-AdoMet adduct is very stable and could be used to identify the AdoMet-binding site on DNA methyltransferases.

Adenosine↗
PubMed1990

Surgical results of intrathoracic gastric volvulus complicating hiatal hernia.

From 1981 to 1988, 138 patients with hiatal hernia were treated surgically at our centre. Twenty-one (mean age 76.6 years, 17 women, four men) had an associated intrathoracic gastric volvulus. Eleven patients (mean age 73.2 years), of whom eight were asymptomatic, had an elective procedure. Ten patients (mean age 80.3 years) had emergency surgery, six for acute complications of the volvulus (five cases of strangulation and one of perforated ulcer) and four because of other, unrelated causes of acute abdomen. There were four deaths after operation, all in the emergency surgery group. Four other patients had significant morbidity, all in the emergency group. In the elective cases, all hernias were easily reduced. In one emergency case a gastrotomy was necessary for decompression, and in another gastrectomy was necessary because of gastric gangrene. Our results indicate the need for elective intervention when intrathoracic gastric volvulus is first diagnosed.

Aged↗