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Biomedical subjects

K Gulabivala

Publications and source records attributed to K Gulabivala.

At least 55 records · Page 3Linked to original sources
PubMed2000

An in vitro comparison of canal preparation using two automated rotary nickel-titanium instrumentation techniques.

AIM: The aim of this study was to compare the efficacy of root canal preparation using two automated rotary nickel-titanium instrumentation techniques with a double flared balanced forces hand preparation technique, using stainless steel files in extracted human teeth. METHODOLOGY: Sixty root canals in extracted human teeth were matched for curvature, length and diameter and divided evenly between three groups (group 1 = double flare using Flexofiles, group 2 = rotary nickel-titanium using McXIM instruments and group 3 = rotary nickel-titanium using Profile .04 Taper Series 29 instruments). The instruments were used according to the manufacturer's instructions in a torque controlled motor and handpiece (groups 2 and 3) and according to a predetermined procedure in group 1. A standardized radiographic technique using mercury as a contrast medium was used to evaluate the canal shape before and after preparation in the plane of maximum curvature. The pre- and postoperative radiographic images were compared against each other and with a predicted 'ideal preparation' calculated from a projection of the final instrument dimensions. The outcome measures were changes in canal dimensions as quantified by measuring the changes in the position of the inner and outer wall at 1 mm intervals. Alteration in canal curvature could be inferred by comparison with the ideal preparation. RESULTS: The degree of canal curvature did not influence the effectiveness of any of the techniques. The results showed no statistically significant differences in the outcome measures between the groups (two-way ANOVA). There were no significant differences in canal wall position changes at any level except the apical three, where significantly less change occurred in all groups (P = 1%). Instruments fractured in three canals, with acute curves in groups 2 and 3. CONCLUSIONS: Canal curvatures were equally and well maintained following preparation in all the groups, as long as the instrument did not fracture.

Analysis of Variance↗
PubMed2000

Advances in endodontics.

Progress in diagnosis, prevention of diseases, treatment of exposed pulp, root canal treatment, retreatment and surgery is reported. Contemporary biological research techniques could set the foundation for a more rational approach to treatment. Pulp inflammation may be prevented by inhibiting bacteria from colonising dentine surfaces. Specific factors could be synthesised to stimulate normal dentine deposition over pulp exposures. Significant improvements have been made in instruments and techniques available for root canal treatment and surgery but there is no clinical evidence that they improve periapical healing.

Dental Leakage↗
PubMed1998

Quantitative analysis of lymphocytes and their subsets in periapical lesions.

The relative proportions of lymphocytes and their subsets in periapical lesions associated with untreated teeth and endodontically treated teeth were compared. Nine periapical lesions associated with previously untreated teeth and six persistent lesions associated with previously root treated teeth which had good quality root canal fillings and coronal seals were selected from a total of 41 samples. Clinical and radiographic features of each lesion were recorded. Serial frozen sections were stained using immunohistochemical methods and monoclonal antibodies against CD20, CD3, CD4 and CD8 to identify B, T, T helper (Th) and T suppressor (Ts) lymphocytes, respectively. Ten microscopic fields, representing the most dense cellular inflammatory infiltrate were selected per specimen and cell numbers were estimated, as a proportion of lesion area, using a point counting method. The periapical lesions associated with untreated teeth had a denser inflammatory cell infiltrate. The proportion of total lymphocytes was significantly higher in the untreated group of lesions (P < 0.01). The proportions of B (P < 0.01), T (P < 0.001) and Th cells (P < 0.01) were significantly higher in untreated teeth. The ratios of Th/Ts cells (P < 0.05) and T/total lymphocytes (P < 0.01) were also significantly different between the two types of lesion. The results show a difference in the inflammatory cell infiltrate and relative proportions of T, B and T helper cells in the two groups of lesions. This indicates that future studies of periapical lesions should take into account the clinical history of the associated teeth.

Adult↗
PubMed1998

An in vitro comparison of thermoplasticised gutta-percha obturation techniques with cold lateral condensation.

This study compared the apical sealing ability, obturation time and extrusion of gutta-percha and sealer when root canals were obturated using either cold lateral condensation or one of the three methods using thermoplasticised gutta-percha (Alpha Seal, Thermafil or JS Quick Fill) in vitro. One hundred and thirty-one root canals from 78 extracted human teeth were used; 116 canals were divided into five groups so that they were balanced with respect to prepared canal anatomy, and the remaining 15 canals were used as positive and negative controls. The canals in the first four groups were prepared with hand files using the step-down technique to a standard apical size and flare. The last group was prepared using engine-driven rotary nickel-titanium files (McSpadden) to a similar apical size and flare. One of the four obturating techniques was used to fill the canals in each of the first four groups. The fifth group was obturated using the Alpha Seal technique. The roots were immersed in india ink, demineralised and rendered transparent to assess the extent of maximum lincar dye penetration. The Alpha Seal groups had the highest number of specimens without any leakage. There was a significant difference in the proportions of specimens that did not leak when the Alpha Seal (P < 0.01) and cold lateral condensation groups (P < 0.05) were compared with JS Quick Fill. Cold lateral condensation had a higher proportion of specimens with leakage in canals with curvature greater than 20 degrees than in canals with curvatures less than 20 degrees (P < 0.05). The curvature of canals had no effect on the sealing ability of the other techniques. The method of canal preparation had no effect on the sealing ability of Alpha Seal. Alpha Seal, Thermafil and JS Quick Fill were significantly quicker to perform than cold lateral condensation.

Analysis of Variance↗
PubMed1997

The use of a 16s rDNA directed PCR for the detection of endodontopathogenic bacteria.

The study evaluates a 16S rDNA directed polymerase chain reaction (PCR) to detect and differentiate bacteria in necrotic root canal samples. The examination focused on species that are fastidious concerning culture or are difficult to differentiate after culturing by biochemical methods. In the described PCR assay, a universal 16S rDNA directed forward primer in combination with a highly specific reversed one was used to amplify taxon specific gene fragments of 230 to 950 bp length. A similar PCR reaction using a universal 16S rDNA reversed primer was also established to demonstrate bacteria in root canal specimens in general. A first application of this method revealed the presence of Actinomycetales-species, Fusobacterium nucleatum, "Streptococcus milleri," and, presumably for the first time described in infected root canals, Bacteroides forsythus. The identity of amplificons was confirmed by generating sequence information and comparison to gene databanks.

Adult↗
PubMed1997

Electrical impedance measurements of root canal length.

Electronic methods are now widely used during endodontic treatment for the assessment of root canal length. These commonly measure the electrical resistance or impedance between the root canal and the buccal mucosa. A number of studies have been undertaken to determine the accuracy of commercially available instruments. The aims of this investigation were to determine the electrical impedance characteristics of the root canal and periapical tissues in vivo, measure the changes relative to the distance of an endodontic instrument from the apical constriction and propose an equivalent circuit modelling the periapical tissues. The length of the root canals of 20 previously untreated teeth were determined using radiographic and electronic methods. Minimal canal preparation was carried out and measurements were made with a size 10 K-Flex file. A microprocessor-controlled LCR analyser was used to measure the electrical impedance characteristics of each root canal. The instrument measured the series and parallel resistive (RS, RP) and capacitance (CS, CP) component of the tissues at two test frequencies, 100 Hz and 1 kHz. Measurements were made for each root canal when the diagnostic file was placed at the apical constriction and repeated when the file was withdrawn to -0.5, -1.0, -1.5, -2.0 and -5.0 mm from the foramen. Readings were taken for each canal after the canal had been dried with paper points, and flooded first with deionised water and then with sodium hypochlorite. The root canals were then prepared, cleaned and obturated using standard endodontic procedures. The LCR analyser selected the series resistance component as the major measurement parameter. There was a clear increase in series resistance (RS) with increasing distance from the radiographic apex for dry canals and those containing deionised water and sodium hypochlorite. The mean resistance for dry canals was markedly higher than for those containing fluid, ranging from 22.19 k omega to 92.07 k omega in comparison with 9.32 k omega to 12.10 k omega for deionised water and from 7.46 k omega to 8.92 k omega for canals containing sodium hypochlorite. There was a marked change in the series and parallel resistive component with distance from the apex, suggesting a complex relationship between the impedance of the smear layer and bulk dentine. The impedance characteristics of a root canal were a complex electrical network comprising resistive and capacitive series and parallel elements.

Dental Pulp Cavity↗
PubMed1996

Evaluation of a pulse oximeter and customized probe for pulp vitality testing.

Current routine methods for assessment of pulp vitality rely on stimulation of A-delta nerve fibers and give no direct indication of blood flow within the pulp. Recent papers have suggested that pulse oximeters may be used to diagnose pulp vitality by detection of blood flow. In this study, an optimized pulse oximeter probe for teeth was designed, built and tested using the Biox 3740 Oximeter (Ohmeda, Louisville, CO). Following preliminary in vitro tests, the probe was tested clinically. Pulse waveforms from maxillary and mandibular anterior teeth were noted. Simultaneous readings from the subjects' finger were used as controls. Pulse wave readings from the teeth were found to be synchronous with the finger probe, but not consistently. It was easier to maintain continuous readings from mandibular incisors than from maxillary incisors. The average percentage synchronization with the pulse was 28.95% for maxillary incisors and 50.28% for mandibular incisors. This difference was significant (p = 0.05). The overall accuracy of the commercial instrument was disappointing, and in its present form it was not considered to have clinical value.

Artifacts↗
PubMed1996

Odontogenic keratocyst as periradicular radiolucency in the anterior mandible: two case reports.

The differential diagnosis of periradicular radiolucencies is broad. Unusual clinical or radiographic features or failure to resolve after quality root canal treatment should be viewed with suspicion and a biopsy specimen should be submitted for histologic examination. Two cases are reported in which the presence of radiolucent lesions could have been mistaken for those of pulpal origin but were subsequently found to be odontogenic keratocysts.

Adult↗
PubMed1996

Influence of storage conditions of extracted teeth on dentine removal by a standardised method of filing.

Extracted teeth are often stored in a variety of solutions for different lengths of time prior to use in studies on the efficacy of root canal preparation. The aim of this study was to evaluate the effect of duration (12 h, 1, 4 and 15 weeks) and type of storage medium (Saline, Formal-saline, Sodium Hypochlorite and Dry conditions) on dentine removal by standardised filing. Apparatus was constructed to standardise variables inherent in filing. These included the file, the rate, duration and amplitude of its push-pull motion, its alignment with a flat dentine surface, the interfacial force (80 gms) and rate of irrigation. Freshly extracted teeth were immediately stored in one of the 13 combinations of storage media and duration. The teeth were prepared into test specimens by splitting the roots and flattening the root canal surface. Twenty specimens were designated to each combination. Dentine removal was quantified by profilometry using maximum depth at 8 selected points. Statistical analysis of the mean values showed highly significant differences (p<0.001) between the media at 1, 4 and 15 weeks.When comparisons of mean values were made within the storage groups, there were highly significant differences (p<0.001) in dentine removal between 0, 1, 4 and 15 weeks of storage in sodium hypochlorite and saline. There were no significant differences found for storage in formal-saline. In dry conditions, the differences were significant (p<0.01) between 0, 1, 4 and 15 weeks of storage, but were not significant when the 4 weeks values were excluded.

Analysis of Variance↗
PubMed1995

An in vivo evaluation of the ENDEX and RCM Mark II electronic apex locators in root canals with different contents.

The accuracy of many apex locators is affected by electrolytes including sodium hypochlorite. According to the manufacturer a new device, the ENDEX, overcomes this problem. The purpose of this study was to assess the accuracy of the ENDEX in comparison with a traditional device, the RCM Mark II. The lengths of 61 canals with various contents (vital pulp, necrotic pulp, pus/exudate, sodium hypochlorite, and water) were determined in vivo. Files were cemented within the canals at lengths determined by the ENDEX. The teeth were then radiographed and extracted, and the distance between the file tip and apical foramen was recorded. Derived readings for the RCM Mark II were compared with the actual ENDEX reading and corresponding radiograph. The results indicated that most of the file tips that were at the radiographic apex actually extended through the apical foramen, and canal content had a varying effect on each device. The overall accuracy of the ENDEX (71.7%) was higher than that of the RCM Mark II (43.5%) within 0.5 mm of the apical foramen. The ENDEX, unlike the RCM Mark II, proved accurate in the presence of sodium hypochlorite.

Chi-Square Distribution↗
PubMed1995

The effect of retrograde cavity design on microleakage of amalgam fillings.

A phantom head model was modified to simulate as closely as possible the limited access encountered during periapical surgery on maxillary anterior teeth. Extracted human maxillary anterior and mandibular canine teeth were placed in this model in a standardized position for root resection, retrograde cavity preparation and filling with amalgam. Three different designs of retrograde cavities were evaluated: the conventional class 1 cavity, the slot cavity and a previously unreported approach, the funnel cavity. Upon completion of the retrograde filling, the teeth were removed from the model and subjected to microleakage tests by placing radiolabelled lipopolysaccharide in a reservoir created coronal to the retrograde fillings. Leakage was quantified by measurement of radioactivity in scintillation counter. It was found that the retrograde fillings in the funnel cavity leaked significantly less than those in the other two cavity designs. There was no statistically significant difference in leakage between the conventional class 1 and the slot cavities up to the thirtieth day 30.

Aggregatibacter actinomycetemcomitans↗
PubMed1995

Clinical diagnosis of internal resorption: an exception to the rule.

This paper describes a case in which the radiographic appearance of a resorptive lesion in a mandibular incisor tooth posed difficulty in the diagnosis of its origin. The lesion did not conform to the normally accepted criteria for diagnosis of internal resorption. Clinical examination did not support the diagnosis of external cervical resorption. Serial histological section of the extracted tooth subsequently confirmed the diagnosis of internal resorption. The criteria for differential diagnosis of resorptive lesions with smooth outlines in the cervical regions of teeth are discussed together with the rationale for their management.

Adult↗
PubMed1995

Intentional replantation: a case study.

Intentional replantation (IR) involves the extraction, extra-oral endodontic treatment and replantation of a tooth. Its use dates back over 1000 years, but it is rarely considered by the modern dental practitioner. This paper describes the treatment of a patient using this technique, and discusses its relative advantages and disadvantages.

Adult↗
PubMed1994

An in-vitro evaluation of the influence of temperature of plasticization on the sealing ability of Thermafil.

The effect of temperature of plasticization on the sealing ability of Thermafil obturators was evaluated. Forty-eight canals in roots of extracted human mandibular molar teeth were divided into four groups of 12. The root canals had curvatures of less than 25 degrees, as determined using the Schneider technique. Four canals were used as positive and negative controls. All canals were prepared using a step-back technique to size 30 at the working length. Roth's sealer was used in all canals. In one group the Thermafil obturators were thermoplasticized in an open flame, as recommended by the manufacturer. In the remaining three groups the obturators were thermoplasticized by immersion in water-baths maintained at constant temperatures of 60, 75 and 90 degrees C respectively. After immersion in Indian ink, the teeth were cleared and the depth of penetration of dye through the apical foramen was measured. In all specimens there was extrusion of sealer and sometimes gutta-percha beyond the apical stop. Sometimes, there was leakage up to the apical stop but not beyond. In view of this the measurements were divided into leakage from the apical foramen to the apical stop and from the apical stop coronally. It was found that in the zone between the apical foramen and the apical stop the Thermafil obturators plasticized at 60 degrees C produced a significantly better seal than those obturators plasticized in an open flame (P < 0.05). In the zone coronal to the apical stop there were no significant differences in leakage between the groups.

Dental Leakage↗
PubMed1994

An in-vitro evaluation of the influence of canal curvature on the sealing ability of Thermafil.

The sealing ability of lateral condensation and Thermafil were compared in root canals with curvatures either greater or less than 25 degrees. Forty-eight canals in roots of extracted human mandibular molar teeth were divided into four groups of 12. The root canals in two groups had curvatures of less than 25 degrees and the remaining two groups had canals with curvatures greater than 25 degrees. Four canals acted as positive and negative controls. All canals were enlarged to accept a size 30 file to the working length and flared using the step-back technique. Roth's sealer was used in all canals. Lateral condensation and Thermafil obturators thermoplasticized in an open flame were used to obturate two groups each of canals, one group with curvatures greater than 25 degrees and the other less than 25 degrees. After immersion in India ink, the teeth were rendered transparent and the linear penetration of dye measured. It was found that Thermafil sealed significantly better than lateral condensation in canals with curvatures greater than 25 degrees (P < 0.05). However, there were no significant differences between the techniques in the groups with canal curvature less than 25 degrees. There was no significant difference in the performance of each of the techniques when analysed with respect to canal curvature.

Dental Leakage↗
PubMed1994

Review of a new root canal obturation technique.

The relatively new technique of obturation using Thermafil endodontic obturators is claimed by the manufacturers to use gutta percha of a more linear structure than conventional gutta percha, and so provide a seal at least equal to laterally condensed material. In this article the authors describe the practical use of this widely marketed technique. Studies which have so far evaluated this technique are reviewed and its advantages and shortcomings discussed.

Gutta-Percha↗