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PubMed1997

Reliability of different electronic apex locators to detect root perforations in vitro.

The aim of this study was to evaluate the accuracy of the electronic apex locator Root ZX compared to the Sono Explorer Mark II Junior and Apit III in detecting root perforations. Extracted human teeth (n = 30) were perforated artificially in the middle third of the root and embedded in a box containing alginate. Detection of all perforations were carried out with K-files attached to the apex locators tested. The teeth were radiographed after each electronic measurement. The actual location of the tip of the file in relation to the external root surface and the radiographic determination of the perforations were carried out using a stereomicroscope. The mean distance of the tip of the file from the external outline of the root surface was short for all instruments and clinically acceptable (0.06-0.25 mm). There was no clinically significant difference between the morphometric measurements and the radiographic measurements. No statistical significance was found between large perforations (0.55-0.60 mm) and small perforations (0.25-0.40 mm). Under the conditions of this study, all electronic apex locators tested were acceptable clinical tools in the detection of root perforations.

Analysis of Variance↗
PubMed1999

Comparison of measurements obtained with hand files or the Canal Leader attached to electronic apex locators: an in vitro study.

AIM: The aim of the present in-vitro study was to combine directly the Canal Leader handpiece (SET, Olching, Germany) with the electronic apex locators ROOT ZX (Morita, Kyoto, Japan) and JUSTY (Yoshida, Tokyo, Japan) to find out whether the working length values thus obtained were identical to those resulting from the combination of the same electronic devices with hand files. METHODOLOGY: A total of 50 natural extracted teeth with single canals and mature apices were used. A radiograph was used as a control and the distance from the radiographic apex to the tip of the file was measured and compared with the results of the electronic length determination. RESULTS: For both electronic devices the differences amongst the distribution of the measurements were not statistically significant under the specified conditions (P > 0.05), indicating that the measurements with hand files and with the Canal Leader were identical for the majority of the cases. CONCLUSIONS: Under the conditions of this study the working length of canals obtained with electronically assisted hand files were similar to those obtained with the electronically assisted mechanical handpiece Canal Leader.

Dental Equipment↗
PubMed1999

In vitro evaluation of the reliability of the Root ZX electronic apex locator.

AIM: An experimental comparison of the Root ZX apex locator with the real measurement of the root canal length was carried out using a saline gel to simulate the periodontium. METHODOLOGY: Lengths were taken when the needle reached the 0.5 mark and the Apex mark on the meter. These measurements were then compared with a calculated reference length representing the real length of the root canal. Reliability was assessed using Student's t-test. Precision was assessed using the mean and standard deviation of differences. RESULTS: The Root ZX gave measurements within a range of 0.5 mm in 84.72% of the cases. The intra-operator and inter-operator variabilities were not statistically significant (P > 0.05). CONCLUSIONS: The Root ZX is not capable of detecting the '0.5 mm from the foramen' position and thus, should only be used to detect the foramen (major diameter).

Dental Instruments↗
PubMed1999

Root canal anatomy of anterior and premolar teeth in Down's syndrome.

AIM: The aim of this study was to examine tooth length and root canal anatomy of 281 anterior and premolar teeth from 66 DS individuals using a standard protocol. RESULTS: The results indicated that root canals in DS are relatively simple and that there is a significant reduction in root and crown length. CONCLUSIONS: We propose that these observations are commensurate with the suggestion that trisomy 21 exerts its effect by slowing the mitotic cycle and rate of cell proliferation, resulting in generalized retardation of growth.

Adolescent↗
PubMed2000

Shaping ability of Hero 642 rotary nickel-titanium instruments in simulated root canals: Part 2.

AIM: To determine the shaping ability of Hero 642 nickel-titanium rotary instruments during the preparation of simulated canals. METHODOLOGY: A total of 40 simulated root canals made up of four different shapes, in terms of angle and position of curvature, were prepared by Hero 642 instruments using a crown-down preparation sequence. Pre- and postoperative images of the canals were taken using a video camera attached to a computer with image analysis software. The pre- and postoperative views were superimposed to highlight the amount and position of material removed during preparation. This report describes the efficacy of the instruments in terms of prevalence of canal aberrations, the amount and direction of canal transportation and overall postoperative shape. RESULTS: Four zips and four elbows were created during preparation, all in canals with 40 degrees, 12 mm curves. No perforations or danger zones were created. Highly significant differences (P < 0.001) were apparent between the canal shapes in total canal width at the apex and beginning of the curve, and in the amount of resin removed from the inner and outer aspects of the curve at the orifice. Canal transportation was most frequently directed toward the outer aspect of the curve at specific points along the canal, except at the orifice, where it was apparent that canals with 20 degrees curves transported toward the inner. Overall, mean absolute transportation was always less than 0.15 mm; however, significant differences occurred between canal shapes at the end-point (P < 0.01), apex of the curve (P < 0.01) and at the orifice (P < 0.01). CONCLUSIONS: Under the conditions of this study, Hero 642 rotary nickel-titanium instruments created canals with few aberrations and no perforations. The relatively high proportion of aberrations in canals with short, acute curves may indicate that instruments with increased taper should be used with caution at or near the full working distance. Further research in real teeth is necessary to elucidate the full potential of these new rotary instruments for use in root canal preparation.

Dental High-Speed Equipment↗
PubMed2001

Methodological considerations in the determination of working length.

AIM: The aim of this study was to evaluate the diagnostic efficacy of an electronic system for the determination of working length, in comparison with two radiological methods (conventional film and digital radiography). METHODOLOGY: The study sample consisted of 28 root canals belonging to 20 human mandibular teeth. A comparison was made between the working length measurements obtained by two radiological methods (conventional film and digital radiography) and an apex locator, using as gold standard the observation of the file position within the root following selective grinding of the root tissue. RESULTS: The electronic method was satisfactory in 67.8% of cases, versus 50.6% and 61.4% for the conventional and digital radiological methods. respectively. No statistically significant differences occurred between the techniques according to the chi-squared and Kruskal-Wallis nonparametric tests. CONCLUSIONS: None of the techniques was totally satisfactory in establishing the true working length. There were no differences between the techniques investigated.

Analysis of Variance↗
PubMed2002

Accuracy of a new apex locator: an in vitro study.

AIM: The purpose of this study was to test in an in vitro model the accuracy of a Bingo 1020 electronic apex locator, to compare the results to those of a well known apex locator, Root ZX, as well as to those of the radiographic method of tooth length determination. METHODOLOGY: A total of 120 extracted teeth, preserved in Thymol solution and kept refrigerated, was used for the study. The experiment was performed on single-rooted teeth and on one-root canal, chosen randomly, in multirooted teeth. The teeth were randomly divided into 12 groups of 10 teeth each. After access preparation, the actual length (AL) was measured. The teeth were embedded in an alginate model specially developed for testing apex locators. Electronic tooth length measurements (EL) were carried out prior to root canal preparation using the two electronic apex locators (EAL) - Root ZX and Bingo 1020; three measurements were taken and an average computed. After the third measurement, the file was left in the root canal and a periapical radiograph was taken. The radiographic length (RL) was recorded by measuring the file length from the coronal reference point to the tip of the file. Each root canal was then prepared to a no. 40 K-file diameter using a standardized technique; saline was used for irrigation. Upon completion of the root canal preparation, EL measurements were taken by each EAL in dry conditions and with different irrigation solutions. Each measurement was repeated three times. The RL was recorded according to the last EL measurement. Results were subjected to statistical analysis. RESULTS: In all parameters tested, a significant statistical difference was found between Bingo 1020 and the Root ZX. Measurements obtained using the Bingo 1020 were consistently closer to the AL (0.08 mm) than those obtained using the Root ZX. Both EALs measured the tooth length with great accuracy and a positive correlation of 0.76 (P = 0.00) existed between the two devices. No significant difference was found between the two apex locators when measurements were taken with the different irrigants (P = 0.34) and the content of the root canal did not affect the accuracy of the measurements. Lengths obtained by calculations from the radiographs were longer than the AL as well as the length obtained by both EALs (P = 0.00). CONCLUSIONS: The Bingo 1020 proved to be as reliable as Root ZX and was user friendly. Under the experimental conditions, electronic measurements were more reliable than radiographs in the process of root length determination.

Analysis of Variance↗
PubMed2002

Does the first file to bind correspond to the diameter of the canal in the apical region?

AIM: The aim of this study was to determine whether the first file that binds at the working length corresponds to the canal diameter. METHODOLOGY: Two similar groups (n = 10) of mandibular premolars with curved canals were selected on the basis of their morphology. Following access and pulp tissue removal, the first instrument that bound in each canal at the working length was determined. In one group the instrument used was a K-file, in the other group a Lightspeed instrument was used. After fixing the instruments in place, the apices were ground to the level of the working length and the diameters of both the instrument and the apical canal were recorded. RESULTS: In 75% of the canals, the instruments bound at one side of the wall only; in the other 25%, the instrument did not contact the wall. In 90% of the canals, the diameter of the instrument was smaller than the short diameter of the canal; this discrepancy was up to 0.19 mm. No significant difference in discrepancy was found between instruments (P > 0.05). CONCLUSIONS: Neither the first K-file nor the first Lightspeed instrument that bound at the working length accurately reflected the diameter of the apical canal in curved mandibular premolars. It is uncertain whether dentine can be removed from the entire circumference of the canal wall by filing the root canal to three sizes larger than the file that binds first.

Bicuspid↗
PubMed2002

Electronic determination of root canal length in primary teeth with and without root resorption.

AIM: To test an electrical device for determining root canal length in primary teeth in vitro, and to compare it with the radiographic length measurement. METHODOLOGY: Two examiners determined the root canal length of 24 extracted maxillary primary incisors (12 with visible root resorption and 12 without) using an electrical root canal meter (Tri Auto ZX, Morita, Dietzenbach, Germany). The instrument was left in the root canal after the second examination and a radiograph was taken. The whole tooth was cleared by immersion in methylsalicylate and subsequently photographed. Both radiographs and photographs of cleared teeth were measured and compared with the electronic measurements. RESULTS: The evaluation of the radiographs showed a mean distance between the instrument tips and apices of 0.60 (+/- 0.41) mm; evaluation of the cleared teeth showed an equivalent distance of 0.62 (+/- 0.40) mm. The mean distance between instrument tip and acceptable working length (determined with the clearing method) was 0.26 (+/- 0.24) mm in teeth without resorption and 0.29 (+/- 0.30) mm in teeth with resorption. CONCLUSION: The presence of resorption in primary teeth did not affect the accuracy of electrical measurement of root canal length in vitro. The application of this method in primary teeth should be evaluated further.

Confidence Intervals↗
PubMed2002

In vivo determination of root canal length: a preliminary report using the Tri Auto ZX apex-locating handpiece.

AIM: The aim of this study was to assess the clinical perfomance of a cordless handpiece with a built-in apex locator - the Tri Auto ZX - designed for root canal preparation with nickel-titanium rotary files. METHODOLOGY: Twenty-five human maxillary incisor and canine teeth scheduled for extraction with mature apices were selected for the study. Informed written consent was obtained from each patient before treatment. After administration of local anaesthesia, the teeth were isolated and the pulp cavities accessed. The Tri Auto ZX along with a size 15 K-file was used in its electronic apex locating function based on the manufacturer's recommendations. A periapical radiograph with the file at the electronically determined constriction was taken, the file removed and the measurement registered as the electronic length (EL). To test the auto reverse function, a size 20 ProFile.04 taper NiTi rotary instrument was mounted in the handpiece. The point for the auto apical reverse function was preset on the panel at the 0.5 mm level. After the file was introduced into the canal and reached the predetermined level, the file automatically stopped and rotated in the opposite direction. A reference point was marked and this measurement was registered as the auto reverse length (ARL). All measurements were made twice by two different investigators. Teeth were then extracted and immersed in a 20% formalin solution for 48 h. After fixation, a size 15 file was inserted into the canal to measure the actual root canal length from the same reference point obtained with the Tri Auto ZX to the apical foramen, as seen in the stereo microscope. When the file tip was visible at the anatomical end of the canal it was withdrawn 0.5 mm and this measurement was registered as the actual length (AL). All measurements were expressed in mm and the measuring accuracy was set to 0.5 mm. The significance of the mean differences between EL and ARL and between EL and AL measurements at the 5% confidence level was evaluated. RESULTS: EL measurements were coincident to ARL in all instances. EL and ARL were coincident to AL in 10 (40%) canals, in the remaining 15 canals (60%) the AL measurements were longer than EL and ARL (+0.5 mm) in 14 instances and shorter (-0.5 mm) in one case. Overall, the AL was longer than the EL or ARL, the mean difference being -0.23 mm +/- 0.32 (P < 0.05). CONCLUSIONS: It was concluded that the Tri Auto ZX was useful and reliable. The Tri Auto ZX measurements protected against overpreparation.

Adult↗
PubMed2002

C-shaped root canals in mandibular second molars in a Saudi Arabian population.

AIM: The aim of this study was to determine the frequency of C-shaped canals in mandibular second molars in a population in Saudi Arabia and to establish a classification for the most common configurations. METHODOLOGY: One hundred and fifty-one mandibular second molars scheduled for root-canal treatment were examined over a 1-year period. The C-shaped canals were detected by radiographic and clinical examination. Teeth with C-shaped canal systems were categorized by using a modification of the classification of Melton. RESULTS: Of the 151 molars, 16 (10.6%) exhibited C-shaped canals. Five molars were classified as category I, and three were considered category II. The remaining eight cases were classified as category III, with two in subdivision I, two in subdivision II, and the remaining four in subdivision IIL. CONCLUSIONS: The C-shaped canals in mandibular second molars vary considerably in their anatomical configuration with the result that debridement, obturation, and restoration may be difficult.

Arabs↗
PubMed2002

In vitro comparison of root-canal measurements with conventional and digital radiology.

AIM: The present study compared the efficacy of digital and conventional radiology for root-canal length measurement. METHODOLOGY: Seventy extracted teeth with pre-served roots were used. Root-canal length measurements were completed with K-Flexofiles (numbers 08, 10 and 15) with conventional and digital radiography using two systems (radiovisiography and photostimulate storage phosphor). All films and sensors were exposed at projections of 0 degrees and 20 degrees to the mesial. The images obtained were evaluated with and without magnification, and analysed using the Cohen's kappa test. The accuracy of the three systems to determine the root-canal length were evaluated by measuring the distance from the tip of the file to the apex. RESULTS: Most of the values corresponding with the apex occurred with conventional radiology. The digital systems yielded negative values that improved with a size 15 file. The agreement between the two digital systems was the best with size 15 file using 0 degrees projection (66.7%). CONCLUSIONS: Conventional radiology remains the technique of choice in determining the root-canal length; the digital techniques yielded good results for size 15 file.

Dental Pulp Cavity↗
PubMed2002

A study on the thickness of radicular dentine and cementum in anterior and premolar teeth.

AIM: This study aimed to measure the thickness of radicular dentine and cementum in incisors, canines and premolars, and to develop geometric average models. METHODOLOGY: The roots of 220 extracted human teeth were sectioned in three horizontal parallel planes and measured using an optical microscope. For each cut surface buccal, lingual, mesial, and distal thickness of the root wall was measured. Mean values of the thickness at each location of each cut surface were calculated. The observed differences in thickness by tooth type, location, and section were compared by ANOVA and Student's t-test. RESULTS: Maxillary central incisors and maxillary canines had the greatest widths. In all teeth with a single root, the wall thickness were greater on the lingual side than the buccal side. Although differences between mesial and distal thicknesses were not statistically significant. CONCLUSIONS: Wall thickness varied greatly. The lingual surfaces of roots were larger. All roots had thin walls in the apical third.

Analysis of Variance↗
PubMed2002

Shaping ability of GTTM Rotary Files in simulated resin root canals.

AIM: The aim of this study was to determine the shaping ability of GT Rotary Files in simulated root canals. METHODOLOGY: Forty canals with four different shapes in terms of angle (40 degrees and 60 degrees) and position of curvature (straight section before curve: 8 and 12 mm) were prepared using a crown-down/stepback technique. Pre-operative and post-operative pictures, recorded using an image analysis system, were super-imposed and aberrations recorded. Measurements were carried out at 5 different points: at the canal orifice (0): half-way to the orifice in the straight section (HO); the beginning of the curve (BC); the apex of the curve (AC): the endpoint (EP). RESULTS: Two instrument fractures occurred and 9 instruments were deformed. Overall, eight zips and one ledge were created. There were significant differences (P < 0.001) for the total width of the canals between the various canal shapes at AC, BC and HO. There were significant differences (P < 0.001) for the amount of resin removed from the outer aspect of the curve at AC, BC and HO; and for the amount of resin removed from the inner aspect of the curve at all five measuring points (0, AC and EP (P < 0.05) and HO and BC (P < 0.001)). Mean transportation was towards the inner aspect of the canal in canals with straight sections of 12 mm regardless the curve angle; towards the outer aspect in canals with straight sections of 8 mm and 40 degrees curves at all the five measuring points, and at AC, BC and HO when the curve was 60 degrees. CONCLUSIONS: Under the conditions of this study, GT Rotary Files produced acceptable canal shapes. In narrow and curved canals, the length of the straight section of the canal determines the direction of transportation more than the angle of the curve. In the 60 degrees curves, a high incidence of instrument deformation was found when using the 0.04 tapered instruments.

Dental Alloys↗
PubMed2002

A simple model to demonstrate the electronic apex locator.

AIM: To describe and evaluate a newly developed model for demonstrating and teaching the use of electronic apex locators. SUMMARY: A phantom model, master jaw model and extracted human teeth were used to construct the demonstration model with alginate impression material as the periapical conductive medium. The model was validated in a series of length determinations with apical foramina enlarged to 0.20, 0.30 and 0.45 mm diameter, and the stability of the model was evaluated up to 45 h after construction. All evaluations were conducted with the Root ZX apex locator with 2.65 and 5.25% NaOCl in the canals. Most length measurements were within 1 mm of actual root length (range: -2.2 to +0.21 mm) and did not change significantly over 45 h for teeth with foramina of 0.3 mm or less. Measurements for teeth with wide (0.45 mm) apices were stable up to 28 h. NaOCl concentration did not significantly affect the readings. KEY LEARNING POINTS: A simple, inexpensive model can be manufactured from plastic dental jaws, natural teeth and alginate impression material to demonstrate electronic working length measurement. The model is stable for many hours and provides consistent results with different concentrations of NaOCl in the canal and various apical diameters. The model is a useful teaching aid but needs further evaluation and refinement before use in research applications.

Alginates↗
PubMed2003

ProTaper rotary root canal preparation: effects of canal anatomy on final shape analysed by micro CT.

AIM: To evaluate the relative performance of ProTaper nickel-titanium (Ni-Ti) instruments shaping root canals of varying preoperative canal geometry. METHODOLOGY: Extracted human maxillary molars were scanned, before and after shaping with ProTaper, employing micro computed tomography (muCT) at a resolution of 36 mum. Canals were three-dimensionally reconstructed and evaluated for volume, surface area, 'thickness' (diameter), canal transportation and prepared surface. Based on median canal volume, canals were divided into 'wide' and 'constricted' groups. Comparisons were made between mesiobuccal (mb), distobuccal (db) and palatal (p), as well as 'wide' and 'constricted' canals, using repeated-measures anova and Scheffé posthoc tests. RESULTS: Volume and surface area increased significantly and similarly in mb, db and p canals, and gross preparation errors were found infrequently. Root canal diameters, 5-mm coronal to the apex, increased from 0.38 to 0.65 mm, 0.42 to 0.66 mm and 0.57 to 0.79 mm for mb, db and p canals, respectively. Apical canal transportation ranged from 0.02 to 0.40 mm and was independent of canal type; 'wide' canals had a significantly higher (P < 0.05) proportion of unprepared surfaces than 'constricted' canals. CONCLUSIONS: Canals in maxillary molars were prepared in vitro using ProTaper instruments without major procedural errors. These instruments may be more effective in shaping narrow canals than wider, immature ones.

Analysis of Variance↗
PubMed2003

Factors influencing the fracture of nickel-titanium rotary instruments.

AIM: To evaluate the effect of rotational speed and the angle and radius of curvature of root canals on the fracture of two types of nickel-titanium rotary instruments: K3 and ProTaper. METHODOLOGY: A total of 240 root canals of extracted human maxillary and mandibular molars were divided into two groups of 120, according to the angle of the canal curvature (group A: <30 degrees, group B: >30 degrees). Each group was then divided into two subgroups of 60 canals in order to perform instrumentation using K3 and ProTaper rotary instruments at three different rotational speeds: 150, 250 and 350 r.p.m. (20 canals at each rotational speed). Each instrument was used a maximum of 20 times and at one rotational speed only. The angle and radius of canal curvature were measured in the only group in which fractures actually took place (group B). RESULTS: There were a total of 22 instrument fractures; all of these occurred in canals with curves >30 degree. In a multivariate analysis, it was demonstrated that the files used at a rotational speed of 350 r.p.m. were more likely to fracture than those used at 250 r.p.m. (OR: 1113.88; 95% CI: 2.36-526420.05) and than those used at 150 r.p.m. (OR: 13531.33; 95% CI: 5.37-34120254.00). A decrease in the angle of curvature of the canal also significantly reduced the likelihood of fracture (OR: 0.2083; 95% CI: 0.068-0.6502). These relationships remained significant after being adjusted for the potential interactions between the remaining variables. No significant differences were found between the files or the radii of the canals. CONCLUSIONS: Instrument fracture was associated with rotational speed and the angle of curvature of the canal.

Dental Alloys↗
PubMed2003

Coronal pulp size in molars: a study of bitewing radiographs.

AIM: To: (i) study coronal pulp dimensions in human first molar teeth; (ii) investigate the effects of restorations on pulp size; (iii) determine differences in dimensions between teeth of Mongoloid patients and teeth of other ethnic groups; and (iv) record the presence of pulp stones. METHODOLOGY: Bitewing radiographs of 121 subjects (mean age, 20.9 years) were taken under standardized conditions. The films were digitally scanned and nine measurements were made from the image of each first molar. The data were analysed in terms of presence or absence of restorations and in terms of racial group. Differences were examined using Student's t-test, Pearson correlations and Levene's test. RESULTS: A total of 445 teeth were analysed. Large crowns were correlated to large pulps. Teeth restored with occlusal and proximal restorations had significantly smaller pulps (P = 0.044 and 0.004, respectively), but no difference was found in pulp area in the clinical crown between the restoration types. Mongoloid crowns were shorter and more bulbous. Pulp areas of maxillary molars and pulp widths at the cervix of mandibular molars were significantly larger in Mongoloids. The pulp area in the clinical crown correlated to pulp horn height for Mongoloids and others and for maxillary and mandibular teeth. No differences were found between the heights of pulp horns in the Mongoloid and other teeth. Four of the pulp measurements demonstrated sexual dimorphism. Stones were present in almost 10% of the subjects, representing 4% of the tooth pulps examined. CONCLUSION: Even teeth with shallow occlusal restorations had reduced pulp spaces. There were significant differences in pulp and crown dimensions between the teeth of Mongoloid patients and those of other patients.

Adolescent↗