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Biomedical subjects

S Montgomery

Publications and source records attributed to S Montgomery.

At least 19 recordsLinked to original sources
PubMed1992

Another look at root canal instrumentation.

Several aspects of root canal instrumentation need additional research. Various factors must be considered in an analysis of instrumentation of the root canal system: the dentin that is cut; the technique used to cut it; the design of the instruments; the material and manufacturing process used to make the instruments; the irrigant used during the procedure; and the anatomic configuration of the root canal system. An analysis of these factors clearly indicates that existing root canal instruments and techniques are less than ideal and, in fact, do not accomplish what is expected of them. Root canals must be properly, but, at the same time, destructive and unnecessary removal of dentin should be kept to a minimum. The Flex-R and Canal Master instruments were developed to address some of the shortcomings of existing instruments and techniques. More scientifically based research is needed to fully evaluate these new instruments and techniques and to develop future instruments.

Dental Cavity Preparation↗
PubMed1992

Evaluation of Thermafil obturation of curved canals prepared by the Canal Master-U system.

A dye penetration study was performed to compare the apical seals obtained with laterally condensed gutta-percha and Thermafil. The sample group contained 40 teeth with curved canals which had been prepared with the Canal Master-U System. Canal curvature was measured and the teeth were decalcified, cleared, and linear dye penetration was measured. Thermafil had statistically more linear leakage as verified by a Wilcoxon test (p < 0.001). Thermafil also had greater variability in the apical seal than did laterally condensed gutta-percha as verified by an F test (p < 0.001). A Spearman correlation analysis (p > 0.05) showed that there was no correlation between root curvature and linear dye penetration.

Analysis of Variance↗
PubMed1992

Cervical canal leakage after internal bleaching.

The effects that walking bleach procedures had on root canal filling leakage and the extent of dentinal penetration were studied. Forty teeth were divided into four groups: 1--GP, set sealer, no base; 2--GP, set sealer, 2-mm Cavit base; 3--GP, unset sealer, no base; and 4--GP, unset sealer, 2-mm Cavit base. All were bleached for 7 days, fresh bleach was added for another 7 days, then methylene blue dye was placed for 5 days. The extent of dye penetration apically along the root canal filling and through the dentinal tubules was evaluated. The results indicate that 2 mm of Cavit was sufficient to significantly reduce linear leakage and dentinal penetration. The Cavit should be placed to a level slightly coronal to the facial cementoenamel junction. Teeth with cemental defects demonstrated greater perpendicular dye penetration in the areas of the defects than those with intact cementum. The data from this study suggest the use of a base material over gutta-percha in clinical practice prior to internal walking bleach procedures.

Analysis of Variance↗
PubMed1992

A comparison of apical seal: chloroform versus halothane-dipped gutta-percha cones.

A dye penetration study was done to compare apical leakage among three groups of extracted teeth obturated with a lateral condensation technique. In one group the master gutta-percha cones were customized in the apical portion of the canals after being dipped in chloroform. A second group used halothane as the customizing agent. No dip was used in the third group, and all three were then laterally condensed. The teeth were cleared and dye penetration was measured. Statistical analysis using a Kruskal-Wallis one-way analysis of variance of the data showed no significant difference among the groups at the p < 0.05 level.

Analysis of Variance↗
PubMed1991

Effect of preflaring on canal transportation. Evaluation of ultrasonic, sonic, and conventional techniques.

This study evaluated the effect on canal transportation when acrylic canals were preflared with Peeso reamers before the use of ultrasonic, sonic, and hand instrumentation techniques. Twenty resin blocks with simulated curved root canals were shaped with each technique to a size 40 file 0.5 mm from the apical foramen. Ten of the canals were preflared in the cervical region with No. 1 and No. 2 Peeso reamers before instrumentation; 10 canals that were not preflared served as controls. Transportation was measured on the inside canal curvature 3 mm from the canal orifice and 8 mm cervical to the working length, and on the outside canal curvature 1 mm cervical to the working length. Statistical analysis with Student's t test did not show a significant reduction in canal transportation for the preflared groups. In some areas the amount of transportation was less for the preflared groups; in other areas it was greater.

Humans↗
PubMed1991

The effects of Canal Master, Flex-R, and K-Flex instrumentation on root canal configuration.

The purpose of this study was to compare the Canal Master instrument and instrumentation technique (CM/CMI) to Flex-R files used with a "balanced force" technique (FR/BF) and K-Flex files used with a step-back filing technique (KF/SB). Thirty-six root canals in extracted human mandibular molars were equally divided into three groups. The roots were sectioned, then photographed and evaluated before and after instrumentation. Evaluation included canal shape, direction and extent of transportation, amount of dentin removed, and centering ability. Canal Master instrumentation and Flex-R/balanced force techniques both produced more round preparations than the K-Flex/step-back. All three techniques resulted in canal transportation, although to varying degrees. Flex-R/balanced forces and Canal Master instrumentation transported very little up to a #30, and Canal Master instrumentation transported significantly less after the #45 instrument at mid-root. K-Flex/step-back removed the most dentin while Flex-R/balanced force removed the least in the apical sections and Canal Master instrumentation removed the least at mid-root. The ability of Canal Master instrumentation to keep instruments centered in the canals was significantly better than for K-Flex/step-back.

Evaluation Studies as Topic↗
PubMed1991

A comparison of weights of debris extruded apically by conventional filing and Canal Master techniques.

Sixty extracted human teeth were divided into three groups of 20 each. Apically extruded debris and irrigant were collected, dried, and weighed by the following three instrumentation techniques: (a) group 1, filing 1 mm short of the foramen; (b) group 2, Canal Master instrumentation to the foramen; and (c) group 3, filing to the foramen (for a relative comparison). The results indicated that all three groups were significantly different from one another. Group 1 had the least amount of debris extruded. Of the two groups instrumented to the foramen, group 3 had twice as much debris extruded as group 2. An apical dentinal plug was frequently found in group 1 and was probably a major reason why this group had the least amount of extruded debris. The significance of this dentinal plug and possible indications for instrumentation to the foramen are discussed.

Analysis of Variance↗
PubMed1991

The solvent effects of calcium hydroxide irrigating solution on bovine pulp tissue.

The solvent effects of calcium hydroxide irrigating solution (used alone and in combination with sodium hypochlorite) on bovine pulp tissue were studied. Forty pieces of pulp tissue weighing 90 mg each were treated with calcium hydroxide solution alone, calcium hydroxide and sodium hypochlorite alternated, sodium hypochlorite alone, and saline alone. Each piece of tissue was treated for 32 min. Desiccated pretreatment and posttreatment weights were compared. There was no significant difference between the dissolution capability of calcium hydroxide solution used alone and of saline. No significant difference was noted between calcium hydroxide solution and sodium hypochlorite used alternately, and sodium hypochlorite used alone. However, both of these groups were significantly more effective at dissolving tissue than calcium hydroxide solution alone or saline. Calcium hydroxide solution was an ineffective solvent of pulpal tissue. If tissue dissolution is desired during root canal therapy, the use of calcium hydroxide solution as the sole irrigant is no more effective than saline.

Analysis of Variance↗
PubMed1991

5-HT reuptake inhibitors, tricyclic antidepressants and suicidal behaviour.

Antidepressant drugs undoubtedly reduce much of the morbidity and mortality associated with a variety of depressive disorders. Certain types of antidepressant drugs have been shown to exert a relative advantage in the reduction of suicidal thoughts, and it is interesting that recent reports have noted an association between the prescription of some antidepressants and the development of suicidal and aggressive thoughts and behaviour. An analysis of the data from double-blind controlled trials of fluvoxamine, fluoxetine and paroxetine indicates that 5-HT uptake inhibitors exercise some protective effects on the emergence of suicidal thoughts, whereas the data from the studies with maprotiline show an increase in suicidal thoughts compared with placebo.

Antidepressive Agents↗
PubMed1991

Antidepressant therapy in the chronic fatigue syndrome.

The chronic fatigue syndrome is a condition receiving increasing recognition. Symptoms of depression are not infrequent and may be persistent and severe enough to warrant treatment. The controversy over the use of antidepressant therapy in this condition may present a dilemma for the general practitioner considering possible treatments. This paper draws on the literature and on the authors' own observations of patients with the chronic fatigue syndrome to suggest guidelines for the use of antidepressant therapy.

Antidepressive Agents↗
PubMed1990

Effect of intracanal medicaments on the sealing ability of TERM.

An in vitro leakage study was performed to determine the effect of intracanal medicaments on the sealing ability of Temporary Endodontic Restorative Material (TERM). Fifty extracted mandibular molars with uniform access preparations were restored with TERM after placement of either a dry cotton pellet (control) or a pellet moistened with eugenol, formocresol, CMCP, or a paste of sodium perborate and superoxol. Multiple quantitative measurements were made on each intact specimen at five time intervals after restoration, and, in some cases, after thermocycling. Statistical analysis revealed no significant leakage in the control group, or in the groups which used eugenol, formocresol, or CMCP when they were compared with the control group. Analysis, however, did show significant leakage for the group containing the bleaching paste. The authors concluded that the sealing ability of TERM is not affected by eugenol, formocresol, or CMCP. However, it should not be used for the temporary restoration of teeth being treated by the walking bleach technique.

Borates↗
PubMed1990

Effectiveness of a brush in removing postinstrumentation canal debris.

The purpose of this study was to evaluate the effectiveness of a brush in removing debris in the root canal after endodontic instrumentation. Seventeen extracted human maxillary first molars with mesiobuccal canal curvatures of 25 to 35 degrees were divided into two groups. After endodontic access and determination of working length, one group was hand instrumented to a #45 file and the other group to a #35 file at the working length. After the teeth were sectioned at the working length and at 2, 4, and 6 mm from the working length, they were evaluated for debris remaining in the canal space. The specimens were reassembled, brushed with an Endobrush, and reevaluated. The scores for instrumentation alone (controls) and instrumentation plus brushing were compared with paired t tests. Instrumentation with brushing was significantly better than instrumentation alone in debriding the root canal.

Dental Pulp Cavity↗
PubMed1989

Effectiveness of ultrasonics and calcium hydroxide for the debridement of human mandibular molars.

This study evaluated the ability of ultrasonics and calcium hydroxide to remove pulp tissue debris from the mesial root canals of human mandibular molars. All teeth were instrumented using a standard filing technique and irrigated with an equal volume of 2.6% sodium hypochlorite before the application of the experimental debridement methods. Debridement comparisons were made of both instrumented and uninstrumented controls at the 3-mm and 1-mm levels of the canals and isthmuses. Statistical analysis showed no differences among the experimental groups or the instrumented controls in the canals at either level or isthmuses at the 3-mm level. In the isthmuses at the 1-mm level, no differences were found among the experimental groups, but they were all significantly cleaner than the instrumented controls. These results indicate that calcium hydroxide and ultrasonics are equally effective in debriding the root canal system, and that both are significantly better than standard instrumentation alone in the isthmuses at the 1-mm level.

Calcium Hydroxide↗