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225 records · Page 13Linked to original sources

PubMed1976

The investigation of microleakage in root canal therapy. An electrochemical technique.

An electrochemical technique employing zero-resistance ammetry is described for evaluating the quantity, rate, and areas permeated in the canal system of a root-filled tooth by 1 per cent potassium chloride. Single-rooted extracted teeth were root-filled by a vertical condensation gutta-percha technique. The teeth were coated from the cementoenamel junction to 3 mm. from the apex with a stopping-off medium, so that the apical foramen and the accessory canals in the area would play a role, but not the lateral canals in the gingival area. The teeth were placed in a potassium chloride solution. When the potassium chloride permeated the apical seal and reached a mild steel rod placed through the occlusal access opening extending 2 mm. into the coronal end aspect of the canal, corrosion of the steel was established and was measured for quantity and rate. This technique suggests the possibility of another pathway for tissue fluid to effect coronal dentinal discoloration. The technique also suggests a quantitative means of measuring apical sealing procedures.

Corrosion↗

PubMed2003

The comparative sealing ability of hydroxyapatite cement, mineral trioxide aggregate, and super ethoxybenzoic acid as root-end filling materials.

A comparison was made of the ability of hydroxyapatite cement, mineral trioxide aggregate, and super ethoxybenzoic acid to prevent the leakage of bacteria from root canals, when used as root-end filling materials. The materials were tested in a double-chamber device in which a root segment connects the upper (delivery) chamber and the lower (receiving) chamber. The root segment was prepared by having the root canal instrumented to a #45 file, and a 3-mm-deep, root-end preparation placed at the apical foramen. The canal of each root segment was filled with gutta-percha, and the root-end preparation was filled with one of three test materials, mixed according to the manufacturer's directions. Negative controls were constructed with sticky wax sealing the apical foramen. A titered suspension of radioactively (3H-thymidine)-labeled bacteria (Enterococcus fecalis) was placed into the delivery chamber, and sterile saline was placed into the receiving chamber such that the apical third of each root section was immersed. At various time points, samples were taken from the receiving chamber, and measured for 3H activity. The results indicated that (a) all the test materials leaked significantly compared with the negative controls; and (b) there was no significant difference found between the leakage rates of the three materials tested.

Aluminum Compounds↗

PubMed1989

In vivo sealing ability of calcium hydroxide-containing root canal sealers.

It was the purpose of this study to determine the sealing ability of 2 commercially available calcium hydroxide-containing root canal sealers, CRCS and Sealapex. One hundred sixty single-rooted human teeth were used. The clinical crowns were removed and the roots were cleaned mechanically and by immersion for 24 h in 5% sodium hypochlorite. The root canals were then instrumented to size 80 at the apical foramen and the roots were sterilized by gamma-radiation. Under aseptic conditions the root canals were filled with a gutta-percha master cone size 70 and Sealapex (48 roots), CRCS (48 roots), and a zinc oxide-eugenol type sealer, Roth 801 (50 roots). The coronal aspects of the root canals were then sealed with zinc oxide-eugenol cement. In order to bring the roots and root filling materials in contact with tissue and tissue fluids, the roots were implanted subcutaneously in rabbits for 90 days and 1 year. Leakage as demonstrated by penetration of India ink was evaluated using a stereomicroscope. The best results were obtained with CRCS. Significantly less leakage occurred with both calcium hydroxide-containing sealers than with the traditional zinc oxide-eugenol sealer.

Calcium Hydroxide↗

PubMed1999

Human teeth with periapical pathosis after overinstrumentation and overfilling of the root canals: a scanning electron microscopic study.

AIM: The aim of this study was to determine whether overinstrumentation followed by immediate overfilling could be a potential risk in the treatment of infected root canals. METHODOLOGY: Thirty-five human teeth with infected root canals were overinstrumented and overfilled approximately 45 min after their extraction. The experimental teeth were enlarged up to size 40 and the overinstrumentation and overfilling were checked with the aid of a magnifying glass. The specimens were fixed in glutaraldehyde plus sodium cacodylate solution and prepared for scanning electron microscope examination. RESULTS: Bacteria were detected on the flute of the files and mostly at the root apices around the main foramen, remaining firmly attached to resorptive lacunae despite the fact that the apices had undergone great changes, including fracture or zipping. A control group consisting of 10 human teeth root canals containing vital pulps were also overinstrumented and overfilled. No bacteria were detected on the flutes of the files, at the apices or on the extruded master cone overfilling these samples. CONCLUSIONS: The high percentage of bacteria adhering to the resorptive lacunae or in the flutes of files used in overinstrumented human teeth with infected root canals carry a potential risk for postoperative pain, clinical discomfort and flare-ups. The hazards observed in these circumstances do not support the one-visit treatment of teeth having acute or chronic periapical abscesses.

Bacteria↗

PubMedDate not supplied

Comparative study to evaluate the efficacy of surgical and conservative techniques for apexification in young permanent teeth with open apices.

The Study was conducted to compare and evaluate the effectiveness of surgical and conservative approach for apexification. Twenty-four non-vital permanent maxillary anterior teeth were selected for this study. The teeth selected were having wide apical foramen and definite radiolucent periapical area. Twelve teeth were treated under conservative method and another 12 teeth with surgical method using 'Renew' (A radioopaque calcium Hydroxide paste). The patient were recalled after 1 1/2, 3, 4 and 6 Months. The results of the study indicated that Calcific bridge formation is rapid in teeth treated with conservative technique. However, periapical repair is accelerated in teeth treated by surgical technique, though the results are comparable at the end of 6 months, So the conservative approach is preferred as it saves surgical trauma. In conservative technique, 75% of the teeth showed calcific bridge formation and 100% showed decrease in periapical radiolucent area by 3.56 mm (mean) after 6 months. In surgical technique the radiographic evidence of calcific bridge formation was noticed in 54.51% of teeth after 6 months. However in 100% of teeth there was decrease in periapical radiolucent area by 3.53 mm (mean) after 6 months.

Calcium Hydroxide↗

PubMed2006

A laboratory analysis of gutta-percha-filled area obtained using Thermafil, System B and lateral condensation.

AIM: To determine the percentage of gutta-percha-filled area (PGFA) in the apical third of root canals when filled with either Thermafil, System B or lateral condensation. METHODOLOGY: Sixty extracted human maxillary central incisor teeth were root filled as following: G1: lateral condensation (n = 20), G2: System B (n = 20) and G3: Thermafil system (n = 20). A horizontal section was cut 2 and 4 mm from the apical foramen of each tooth. The samples were prepared for microscopic analysis and photomicrographs of each apical surface were taken at a magnification of 50x. Through digital image analysis, the cross-sectional area of the canal and the gutta-percha was measured. The PGFA was calculated. The PGFA data obtained in the three groups were analysed using a nonparametric Friedman and Wilcoxon signed-rank tests. RESULTS: Significant differences in PGFA were found between the Thermafil System (G3) and both System B (G2) and lateral condensation (G1) (P < 0.01). The greatest PGFA occurred in the Thermafil group. No significant statistical difference was found between System B and lateral condensation (P > 0.05). CONCLUSIONS: The coated carrier gutta-percha system Thermafil produced significantly higher PGFAs than lateral condensation and System B techniques.

Anatomy, Cross-Sectional↗

PubMed1993

[Evaluation of the apical seal of endodontically treated teeth by the ion-diffusion method].

It is generally accepted that improper preparation of the post space in endodontically treated teeth may damage sealing of the filling and cause treatment failure. Conventional method of detecting the sealing ability of endodontically treated teeth are quite complicated and inconvenient. To avoid the shortcomings of these traditional methods, the law of diffusion was adopted in this experimental design, and the results were compared with those of the traditional dye penetration method. Fifty sound molar teeth were treated by routine endodontic procedures, and were instrumented to 35# endodontic file. In 20 teeth in the control group, half were treated as a positive control by leaving the apical foramen open, and the remaining half were used as a negative control by sealing the foramen with two layers of nail polish. The other 30 experimental teeth were filled with gutta-percha points and sealer Canals by the lateral condensation method. Two weeks later, the filling material was removed to apical 3 mm, then 60 microL 2915 mM KCl solution was placed into the pulp cavity. The root was immersed into 1 mL 24.17 mM KCl solution. During the following 30 days, the concentration of the potassium ions in the outer solution was monitored by an ion-selective electrode. Finally, all 50 teeth were immersed in 1% methylene blue for 24 hours, sectioned with Isomet, and the extent of dye penetration was measured under a stereomicroscope with a digital caliper. The results of both methods were compared by means of regression analysis. There was a good correlation between the dye penetration method and the newly designed ion-diffusion method (r = 0.812).(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Leakage↗

PubMed1995

Efficacy of XeCl-308 excimer laser in fusing hydroxyapatite to seal the root apex.

Sealing the root apex during apical surgery is important for a successful outcome. The effect of XeCl-308 nm excimer laser irradiation on the fusion and seal of hydroxyapatite to the root apex was tested in extracted human teeth. Twenty-four roots of intact single-rooted premolars were instrumented to size 30 K-file at the apex leaving a patent apical foramen. The apex of each tooth was covered with a freshly prepared paste of hydroxyapatite powder mixed with saline. The samples were then divided into two groups. In 12 teeth, the apical area was irridiated with XeCl-308 nm excimer laser at a fluence of 0.7 J/cm2 for 5 s with pulse repetition rate of 25 Hz and a spot size of 0.13 cm2 immediately after the hydroxyapatite application. In the other 12 teeth, no laser treatment was performed after the hydroxyapatite application. The roots were mounted on a model for the detection of radicular leakage of hydrogen peroxide. The hydrogen peroxide leakage of each sample was measured and the difference between the test groups compared. The ability of the hydroxyapatite plug to prevent hydrogen peroxide leakage at the apex was also tested by applying compressed air from the triple syringe on the coronal access preparation for 2 min. Apical leakage was found in four teeth in the lased group and in eight teeth in the non-plased group. However, the difference between the groups was not statistically significant. Compressed air applied to the coronal access caused hydrogen peroxide leakage in all the teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Chi-Square Distribution↗

PubMed2002

A preliminary study of the percentage of gutta-percha-filled area in the apical canal filled with vertically compacted warm gutta-percha.

AIM: The aim of this study was to determine the influence of the width of apical root canals and the depth of heat application during warm vertical compaction on the percentage of gutta-percha-filled area (PGFA) in the apical root canal. METHODOLOGY: Two groups of extracted human canines (total 60) were instrumented and filled with vertically compacted warm gutta-percha up to the apical foramen (AF). Using the Touch 'n Heat device heat was applied 4 mm from the AP in one group and 2 mm in the other. The number of teeth with gutta-percha extrusion was recorded. A horizontal section was cut 1.5 mm from the AF of each tooth. The cross-sectional area of the canal and the gutta-percha was measured using an image-analysis programme. The PGFA was then calculated. Multiple linear regression was performed to investigate the association between the experimental variables and the PGFA, and the occurrence of gutta-percha extrusion. RESULTS: A significant association was seen between the depth of heat application and the PGFA (P= 0.000), and between the canal area and the PGFA (P= 0.038). The average PGFA reached 96.1% when heated to 2 mm, as compared with 87.0% when heated to 4 mm. PGFAs were lower in wide apical canals than in small canals. Gutta-percha extruded in seven teeth (12%) and was independent of experimental variables. CONCLUSIONS: After warm vertical compaction, the quality of adaptation of gutta-percha to the wall of the apical root canal varies; the influencing factors in this study were the depth of heat application and the width of the apical root canal.

Cuspid↗