Effect of dowel preparation on the apical seal of obturated root canals by three obturation techniques

Creating a space to receive the dowel is a very critical phase of the fixed prosthetic treatment because it necessitates the removal of a portion of the root canal filling material. The degree of the apical leakage was measured quantitatively after the preparation of dowel space at 3 and 4mm levels in roots which had been filled by three techniques for gutta-percha condensation. Best sealing results were obtained at the level of 5mm when vertical and automatic condensation techniques were used

effect of smear layer removal on the root canal sealability when using composite bonding agent and Grossman's sealer

Sixty teeth were used and divided into three equal groups. All root canals were prepared using the step-back technique and 5.25% NaOCl as an irrigation. For the first group, the roots received their final irrigation with 20 ml of EDTA followed by 10 ml of NaOCl then with 10 ml distilled water. The same technique was used for the final irrigation of the roots of the second group except that 50% citric acid was the chelating agent used. The third group was left as control. Each group was subdivided into two subgroups, roots of the first subgroups were filled with gutta percha using Grossman's root canal sealer, while those of the second subgroup were filled with gutta percha using composite bonding agent as a root canal sealer. The degree of leakage was assessed by the linear dye penetration method. From the results obtained, the sealing ability of the composite bonding agent was not relatively higher than that of Grossman's sealer, but the use of the smear layer removal agents improve significantly the sealing efficiency of the two sealing materials used in this study

Systematic tolerance to the conventional and high copper dental amalgam implants

Freshly mixed, unset amalgam of four different types have been implanted in rats tibias for the purpose of evaluation of the effect of their corrosive products on some vital organs; the liver the kidney and blood. The animals were sacrificed after taking the blood samples at 1, 2, 4 and 6 week intervals. Liver and kidney function tests were done. The amount of copper and Zinc in the serum were measured using an Atomic Absorption spectrophotometer-. No significant differences were observed between the control group and the other different between the control group and the other different groups; the corrosive products of the different types of amalgam alloys did not affect the liver and kidney functions, the normal concentration of Cupper and Zinc in blood was not altered

Histological and histochemical evaluation of the effect of povidone iodine versus sodium hypochlorite on the rat connective tissue

Betadine was used in different concentrations ranging from 1% to 10% to study its histological and histochemicol effect on the connective tissue of the adult rat skin. Also a comparison was performed between the effect of betadine and 5% sodium hypochlorite on the some tissue. The lower concentrations of betadine up to 4% gave no injurious action, while 6% betadine was of a relatively lesser tissues reaction than 5% sodium hypochlorite. However, the tissue reaction resulted from 8% betadine was approximately similar to that reported with 5% sodium hypochlorite, Severe tissue reaction was demonstrated with 8% and 10% betadine, which makes the use of this high concentration in root canal disinfection contraindicated

Comparative bacteriologic study of five root canal sealers

5 root canal sealers were tested bactariologically against four micro-organisms commonly found in the root canals these were Streptococcus veridans, Staphylococcus aureus, E. coli, and Candida albicans, The sealers tested were kerr Tubli seal, Diaket, No genol, Roth sealer and zinc oxide-eugenol. Diaket and sealers containing eugenol gave the best results where as no genol and tubli seal gave the narrowest zones of inhibition

Study of the antimicrobial efficiency of some root canal medicaments

Four types of intra-canal medicaments were used in this study to evaluate their antibacterial efficiency against streptococcus viridians, staphylococcus aurous, E. coli and Candida albicans, These medicaments were divided into: 1] Fixative; form cresol in three concentrations, full concentration of Buckley's formula, 1/5 and 1/10 concentrations of the formula; and glutaraldehyde in five concentrations 19% 3% 3% 2% and1% 2] Irrigating solutions; hydrogen peroxide in 10 and 3 volumes' and sodium hypochlorite solution in 5% concentration. These following conclusions could be abstained from this work: 1] Formocresol in Buckley's formula have the widest inhibition zone in all microorganisms used. 2] The second zone of inhibition was produced by sodium hypochlorite 5% solution. 3] Glutaraldehyde solution even in 19% concentration is not a powerful antimicrobial agent against the micro-organisms tested in this study. Chemical treatment of the pulp canal spaces has logn been practiced in dentistry. The original agents were sodium hypochlorite solution in 5% concentration, and formocresol in the concentration formulated by Buckley. During the past fifteen years a number of studies have indicated that the negative results of formocresol could be due to the excessively high concentration of the Buckley's formula. These studies have shown that a one - fifth dilution of Buckley's formula appears biologically as effective as the full strength formocresol preparation and allows for a faster recovery of the cells. The destructive chemical reactions of protein, nucleic acid, and carbohydrates with formaldehyde have been reported. They concluded that formocresol when contacting vital tissues might irreversibly damage biologically active proteins and enzymes, genetic materials, membranes and elements of the connective tissue. Because of these problems, recent studies have attempted to find alternative drugs which would be more biologically compatible than formocresol. One such drug that has been suggested and received most attention is glutaraldehyde."S-Gravenmade"75[15] reported that glutaraldehyde has better fixing and disinfecting properties, and as a larger molecule, has less tendency to diffuse out of the root canal into the periodical region in pulpotony procedures.Despite claims that glutaraldehyde might be a better agent than formocresol biologically, bateriologic evaluation of these drugs in different concentrations has not been studied. In this investigation attempts to study the antimicrobial ability of different concentrations of formocresol and glutaraldehyde, and two widely used irrigating solutions are reported

Bone response to zinc and non-zinc silver amalgam implants

Freshly mixed, unset zinc free and zinc containing amalgam were implanted in the right and left tibias of twelve Sparque-Dowley rats. Specimens were examined under light microscope. Animals were sacrifised after one, two, four and six weeks period. Acute inflammatory reaction was observed after one week in zinc containing implant while it was mild in non-zinc amalgam implants. This inflammatory reactions gradually reduced by time until disappeared after four weeks as the zinc cautions were released from one to thirty days

effect of calcium hydroxide upon the surface properties of dentin

The surface scratch of dentin was performed before and after application of calcium hydroxide paste. Scratching was done using a Vicker Hardness tester. Dentin surface was subjected to a load of 300 gm. under a speed of 1 mm/min. Width of scratch was measured using a sterio-micro scope. The effect of water storage of samples on the surface scratch was studied. Calcium hydroxide powder increased the resistance of dentin to scratch up to 10%, the storage time had no effect on increasing the dentin hardness when compared to 15 days storage results

comparative evaluation of the retention of two different posts and their effect on the strength property of the roots

A total of eighty freshly extracted human maxillary central incisors and canines were used for post hole preparation after been filled with gutta percha by the ordinary methods. Roots were divided into two groups. The first group was subjected to retention analysis, while the second to mechanical stress one. Each group of teeth was subdivided according to the post design into two subgroups; the first received threaded posts, ten of diameter 2 and ten of diameter 6. The second subgroup received casted posts, ten of diameter 2 and ten of diameter 6. The difference in post diameter had no significant effect on the retention of threaded posts while it played an important role in the casted ones. When both post designs subjected to a 450 angle load, fracture of the roots at their cervical one third occurred