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At least 433 records · Page 24Linked to original sources
PubMed2004

Perforation risks associated with the use of Masserann endodontic kit drills in mandibular molars.

PURPOSE: The use of Masserann kit is a frequently recommended technique for the removal of canal obstructions. Although this technique is usually successful, it may cause excessive removal of dentin tissue in root canals. The aim of this study is to evaluate the perforation risk and the remaining dentin thickness in mesial canals of mandibular molars following the use of Masserann kit. STUDY DESIGN: Fifty-three extracted human mandibular molars were selected for the study. The teeth were separated into 3 groups based on the degree of curvature of the root canals. By using Radio Visio Graphy and Coral Draw 8.0 software packages, the dentin/cement thickness of root canal was measured before and after the use of Masseran kit drills. RESULTS: In the severely and moderately curved mesial root of mandibular molars, the Masserann Kit increased the risk of creating thin or perforated walls. Additionally, after 7.5mm depth of drilling, the percentage of perforations increased in all groups. CONCLUSIONS: With respect to endangering the dentinal walls towards the apex of root canals, Masserann kit drills were found to increase the risk of perforations in curved canals and in deep preparations.

Chi-Square Distribution↗
PubMed2004

Evaluation of different methods for the root-end cavity preparation.

OBJECTIVE: The dentinal walls of root-end cavities were examined for the presence of cracks and debris in correlation with the area of the root surfaces that remained after the resection. STUDY DESIGN: One hundred extracted single-rooted teeth were endodontically treated, mounted in acrylic resin blocks, and the apical 2 mm of the root-apex was resected. According to the resected root surface area the teeth were divided into 2 groups having large (>2 mm(2)) or small (<2 mm(2)) surface area. For retrograde cavity preparation 4 devices were used: slow-speed handpiece, diamond coated stainless steel ultrasonic tip, smooth stainless steel ultrasonic tips, and sonic diamond-coated tips. Teeth were examined under a videomicroscope for the presence of fractures, dentin chips, and gutta-percha remnants on cavity walls. Preparation time was also recorded. RESULTS: Preparation with smooth stainless steel ultrasonic tips produced few intradentin cracks. Dentin debris was more frequently seen in rotary preparations whereas gutta-percha remnants were seen mainly at ultrasonically prepared teeth. CONCLUSIONS: Sonic and ultrasonic devices produced cleaner, well-centered, and more conservative root-end cavities than the rotary instrumentation. Cracks do not correlate directly with the surface area of the root-end surfaces but rather with the type of retrotip used to prepare the root-end cavity.

Apicoectomy↗
PubMed2005

Accuracy of ultrasound measurement of progressive change in occlusal enamel thickness.

OBJECTIVE: To evaluate the effectiveness of ultrasound on measuring the thickness of enamel in abrasion. STUDY DESIGN: Flat areas on occlusal surfaces of 20 premolar teeth were marked. Two initial ultrasonic measurements on marked areas were obtained by the first researcher. Then the tooth was measured in the axial direction with a compass. The cusp tips were abraded by an abrasive paper, then the second and third ultrasonic measurements were taken. The second researcher repeated the third ultrasonic measurement to evaluate the interobserver variation. All specimens were sectioned and the remaining enamel thickness was measured under polarized light microscope. RESULTS: Pearson's correlation analysis showed a high level of intraobserver agreement for the ultrasonic measurements of the first researcher (r = .891, P < .000 initial; r = .690, P < .001 first abrasion; r = .885, P < .000 second abrasion). Third ultrasonic measurements of the first and second researchers were positively and significantly correlated with histological readings (r = .966, P < .000; r = .466, P = .039). CONCLUSIONS: The ultrasonic system used in this study was reliable in measuring enamel thickness.

Bicuspid↗
PubMed2005

The risk of furcal perforation in mandibular molars using Gates-Glidden drills with anticurvature pressure.

OBJECTIVE: The aim of this study was to determine whether using Gates-Glidden (GG) drills and anticurvature pressure in curved mesial root canals of mandibular molars could remove more dentin from the mesial canal wall and remove less dentin from the distal canal wall at a level 2 mm below the furcation. STUDY DESIGN: In 5 groups of mesial roots with an average curvature of 32-34 degrees, 103 canals were prepared using a size #2 or #3 GG drill in the coronal third (straight portion of the canal only) or coronal half (straight portion and part of the curved portion), with or without applying anticurvature pressure. Using a modification of the Bramante muffle mold the cross-section of the mesial root at 2 mm below bifurcation was photographed twice, before and after the use of GG; the photos were then scanned as tagged image files. The thickness of the mesial and distal canal walls wer measured using an image analysis program. The reduction of the wall thickness after the use of GG was calculated. RESULTS: Before enlargement, the average and minimal thickness of the distal wall was 0.92 and 0.43 mm respectively, thinner than that of the mesial wall (1.50 and 0.87 mm, correspondingly). After the use of GG, the reduction of the mesial wall was similar to the reduction of the distal wall (P > .05 for all groups). In 4 groups the maximal reduction of the distal wall was > or =0.72 mm. CONCLUSIONS: After using GG drills and anticurvature pressure, dentin was uniformly removed regardless of the size of the GG and the depth of placement of GG. Flaring with GG drills in mandibular molars may result in perforations; application of anticurvature pressure did not reduce the risk.

Dental Instruments↗
PubMed2005

Accuracy of film-based, digital, and enhanced digital images for endodontic length determination.

OBJECTIVE: This study compared the accuracy of D- and F-speed intraoral radiographs and digital and enhanced digital radiographic images for endodontic file length determination. STUDY DESIGN: Size 15 K-files were bonded in 51 canals of 34 human cadaver teeth. The distance from file tip to root apex was measured on D- and F-speed film and on unenhanced and enhanced digital images. The quality of the images was rated by the observers. Overlying cadaver bone and root structure were subsequently removed to expose the file tip for actual measurement to the apex. The distance measured on each image was compared with the actual measurement. ANOVA, Kruskal-Wallis, sign test, and Pearson correlation statistical analyses were applied. RESULTS: There were no significant differences in measurement accuracy among the 4 image types (P < or = .05). Subjective ratings showed a preference for the quality of enhanced digital images. Conclusion All 4 image types were similar in accuracy of file measurement. The image quality of enhanced digital images was subjectively superior to the others.

Analysis of Variance↗
PubMed2005

Radiographic proximity of the mandibular third molar to the inferior alveolar canal.

OBJECTIVE: To determine the panoramic radiographic distance from the mandibular third molar tooth to the inferior alveolar canal. STUDY DESIGN: Five hundred sixty mandibular third molars were evaluated by panoramic radiography. The teeth were grouped into erupted vs unerupted and further subdivided by tooth angulation. The distance from the most inferior aspect of the mandibular third molar tooth to the superior border of the inferior alveolar canal was measured with digital calipers. A t test was performed to compare erupted and unerupted teeth, and ANOVA was used to determine if a significant difference exists based upon tooth angulation. A record review was performed to assess the incidence of inferior alveolar nerve paresthesia based upon measured distances. RESULTS: The mean distance from erupted mandibular third molar teeth to the inferior alveolar canal is 0.88 mm. This distance was significantly different from unerupted teeth (P=.002). The mean values for unerupted teeth indicated that the most inferior portion of all teeth measured was below the superior border of the canal (negative values) as follows: mesioangular (-0.97 mm), vertical (-0.61 mm), distoangular (-0.31 mm), and horizontal (-0.24 mm). The position of mesioangular impactions were significantly different than all other impaction groups (P=.0125). The incidence of inferior alveolar nerve paresthesia was 3.33% (18/541), most commonly associated with mesioangular impactions (-0.66 mm) in female patients. CONCLUSIONS: Unerupted mandibular third molar teeth are closer to the inferior alveolar canal than are erupted teeth. Mesioangular mandibular third molar impactions are most closely positioned to the inferior alveolar canal, and this may represent an independent risk factor for postoperative paresthesia.

Adult↗
PubMed2006

Panoramic radiographic predictors of mandibular third molar eruption.

OBJECTIVE: Third molar (M3) eruption can be problematic. According to some orthodontic surgeons, the teeth are capable of aggravating the average crowding level in the dental arch. The question is whether it might be possible to give a prognosis for ultimate M3 position in the arch and make an early decision to extract or retain them. The purpose of the study was to determine which measurements made on panoramic tomograms might facilitate prognosis for M3 position in the dental arch over the years. STUDY DESIGN: The investigation involved 64 patients who had been enrolled to the study group 10 years earlier, ie, in 1993, when an analysis had been carried out regarding M3 effect on dental arch crowding. At that time panoramic tomograms had been taken, and dental casts made. The procedures were repeated in 2003. The following measurements were taken at baseline (1993) and at the end of the study (2003): (1)/the retromolar space to lower third molar crown width, (2) third molar angulation to the base of the mandible, and (3) third molar to second molar inclination. RESULTS: At some defined values of the Ganss ratio, and M3 inclination to mandibular base and second molar, it is possible to predict potential lower third molar alignment in the dental arch using a panoramic radiograph.

Adolescent↗
PubMed2006

The Ekman-Westborg and Julin trait: report of a case.

Macrodontia associated with multituberculism, central cusps, and pulpal invaginations is reported in a 7-year-old Hungarian girl. Over 5 years' follow-up the problems of the diagnosis, the similarity with and relationship to the Ekman-Westborg and Julin trait, and the difficulties of the treatment are discussed.

Bicuspid↗
PubMed2006

Correlation between maxillary sinus floor topography and related root position of posterior teeth using panoramic and cross-sectional computed tomography imaging.

OBJECTIVE: This study correlated the topographic relationship of the maxillary sinus floor to the roots of posterior teeth imaged by panoramic radiography and cross-sectional computed tomography (CT). STUDY DESIGN: Paired panoramic radiographs and CT images of maxillae from 80 subjects were analyzed. A total of 422 maxillary roots were classified according to their topographic relationship to the maxillary sinus and measured according to their projection lengths on the sinus cavity for both imaging modalities. Correlations between the 2 radiographic techniques were examined statistically. RESULTS: Teeth roots that did not contact the sinus floor or contacted it but did not project on the sinus cavity (classifications 0 and 1) showed a high agreement of 86% to 96% when using the 2 imaging techniques. Only 39% of the teeth roots that projected on the sinus cavity in panoramic radiographs (classification 3) showed protrusion into the sinus with CT. The panoramic radiographs showed a statistically significant 2.1 times longer root projection on the sinus cavity in comparison to the root protrusion length into the sinus measured by using CT images (P < .001). CONCLUSION: For the majority of the roots projecting on the sinus cavity in panoramic radiographs, no vertical protrusion into the sinus was observed in CT images. Roots that did protrude into the sinus in the CT showed a protrusion length that was much shorter than the projection length appearance using panoramic radiography.

Bicuspid↗
PubMed2006

A clinical method to determine the optimal apical preparation size. Part I.

OBJECTIVE: To establish a new approach for determination of the optimal apical preparation size (APS). STUDY DESIGN: After preflaring 212 root canals from 80 extracted molars, electronic working length (WL) was measured to establish where the apical preparation size (APS) should be determined. Subsequently, nontapered, noncutting special instruments were used to reach WL. The diameter of the largest special instrument (SI) width that had to overcome some resistance to advance to WL was defined as d(SI). After sectioning the roots apically, the diameter of a potential rotary instrument was determined for each section, allowing a complete cutting of the root canal wall. The estimation of APS was related to d(SI). RESULTS: Theoretically, individual APS of d(SI) + 0.60 mm yielded circumferential apical preparations in 98% of the cases. When shaping palatal/distal root canals of molars to d(SI) + 0.40 mm, and mesiobuccal/mesiolingual/distobuccal root canals of molars to d(SI) + 0.30 mm, complete preparations of root canal walls resulted in 78% (95% CI, 69%-87%) and 72% (95% CI, 65%-80%) of canals, respectively. CONCLUSION: The described approach allowed evaluation of the APS for most root canals. Root canals should be shaped to larger sizes than normally recommended.

Algorithms↗
PubMed2006

Extended apical enlargement with hand files versus rotary NiTi files. Part II.

OBJECTIVE: The objective of this study was to compare 2 preparation techniques performed under simulated clinical conditions with extended apical enlargement following determination of the optimal apical preparation size (APS). STUDY DESIGN: After preflaring 240 root canals, APS was evaluated as outlined in Part I. The apical portion was shaped to APS either with rotary NiTi Lightspeed instruments (LS) or NiTi hand instruments (HA) using the balanced force technique in a phantom head. After sectioning the apical area at 3 levels, every cross section was analyzed microscopically for circumferential removal of canal wall dentine. Loss of working length, instrument separation, and perforation were additionally recorded. RESULTS: In 70% (LS) and 69% (HA) of the root canals, 2 of 3 levels demonstrated that the root canal dentin was cut circumferentially. Neither loss of working length nor perforation occurred in both groups. Four LS instruments separated. CONCLUSIONS: APS frequently results in a nearly complete apical preparation regardless of the preparation techniques. In a few cases apical enlargement to APS does not achieve complete cutting of the canal walls. There was a rather slight risk of serious procedural errors.

Algorithms↗
PubMed2006

The correlation between root canal patterns and interorificial distance in mandibular first molars.

OBJECTIVES: The aim of this study was to investigate the relationship of the distance between mesiobuccal (MB) and mesiolingual (ML) orifices (interorificial distances) in the pulp chamber floor and the degree of canal curvature in the mandibular first molars. STUDY DESIGN: In this in vitro study, 102 extracted teeth were radiographed in both buccolingual (CV) and mesiodistal (PV) directions and then grouped according to the Vertucci classification. The interorificial distance was measured by the stereomicroscope method. RESULTS: The interorificial distance was significantly higher in type IV compared to type II (P= .016). In the logistic regression analysis, the increase in the degree of primary canal curvature of the ML in CV was a predictive factor for increase in the primary curvature of ML in PV (P = .01). CONCLUSION: The interorificial distance in the pulp chamber floor and primary curvatures in CV were found to be key factors for evaluation of root canal patterns in PV.

Analysis of Variance↗
PubMed2006

Comparison in vivo of the first tapered and nontapered instruments that bind at the apical constriction.

OBJECTIVE: To compare sizes of the first instrument with or without taper that binds to the narrow apical diameter of the root canal after coronal flaring. STUDY DESIGN: For the study, 388 canals were examined in patients with intact apices. A standard endodontic access cavity was prepared and the coronal third flared using standardized K-files, Gates Glidden reamers, or Profile rotary instruments. Apical patency was established using K-file size 10 and working length determined using an apex locator and radiographs. Standardized K-file hand instruments were gently introduced to working length beginning with size 15. The first K-file to bind to the canal walls and reach the working length was recorded as FKFB. Nontapered instruments (Lightspeed) were then gently introduced by hand to each canal in ascending order beginning with size 20 to working length. The first instrument to bind to the canal walls and reach the working length was recorded as FLSB. Statistical analysis was carried out using univariate analysis of variance. RESULTS: The average size of FLSB was approximately 2 ISO sizes larger than FKFB (P < .001). Minimal differences were found in the maxillary central incisors (6.7 +/- 3.0) and maximal differences in canals from maxillary lateral incisors (15.4 +/- 3.5). CONCLUSIONS: The first nontapered instruments to bind at the apical constriction were larger and reflected the actual narrow apical diameter of the canal better than the tapered instruments.

Dental Instruments↗
PubMed2006

Accuracy of the apex locating function of TCM Endo V in simulated conditions: a comparison study.

OBJECTIVE: The aim of this study was to evaluate the accuracy of the apex-locating function of the TCM Endo V and to compare the results to these of the Root ZX. STUDY DESIGN: Forty-seven extracted maxillary incisor teeth with mature apices and patent single root canals were used for the study. After the root surfaces were cleaned and access cavities were prepared, the true working lengths (TL) were determined with a #10 stainless steel file. All samples were mounted in an alginate model especially developed to test the apex locators. Both electronic apex locators were used according to the manufacturer's recommendations and adjusted to 0.5-mm accuracy to the apical foramen. EL(1) was designates as the working length measured with Root ZX and EL(2) was designated as the working length measured with TCM Endo V. A paired t test was used to statistically analyze the significance of the mean differences at the 95% confidence interval of the differences (P = .001) among TL, EL(1), and EL(2). RESULTS: There were no statistically significant differences between TL and EL(1), TL and EL(2), and EL(1) and EL(2) (P = .001). Both Root ZX and TCM Endo V gave similar results. CONCLUSIONS: TCM Endo V proved to be as reliable as Root ZX but the use of the device to determine the working length was not easy as Root ZX. Further studies are needed to compare TCM Endo V in clinical conditions with similar electric motor and apex locator combined devices.

Dental Instruments↗
PubMed2007

Detection of a second mesiobuccal canal in the mesiobuccal roots of maxillary first molar teeth.

OBJECTIVE: The aim of the present study was to determine whether the MB2 canal in the mesiobuccal root (MBR) of maxillary first molars could be identified through a clinical access cavity preparation, with and without magnification. STUDY DESIGN: One hundred extracted maxillary first molar teeth were collected. After a clinical access cavity preparation with careful use of bur to locate any additional canal (dentine troughing), the MB2 canals were located in 2 stages. Stage I was located with unaided vision and stage II was located under moderate magnification with x3.5 magnifying dental loupes. All specimens were stained, rendered transparent, and then classified. The number of canals detected by stage was analyzed statistically by a chi-square test. Statistical significance was considered to be P < or = .05. RESULTS: Under magnification, the number of detected MB2 canals was increased from 55 (56.7%) to 61 (62.9%) teeth. Cleared teeth showed 77.32% of MB2 canals. The effectiveness of MB2 location was 73.3% and 82.7% in stage I and stage II, respectively. There was no statistically significant difference between the 2 methods of detecting the MB2 canal (P = .3). CONCLUSIONS: The use of magnification enhanced the ability to detect the MB2 canals, although the difference was not statistically significant. The MB2 canals could not be detected in 16.5% of the teeth, mainly because of pulpal calcification.

Dental Instruments↗
PubMed2004

Directing ultrasound at the cemento-enamel junction (CEJ) of human teeth: I. Asymmetry of ultrasonic path lengths.

The diagnosis of degenerative changes in human teeth is of general interest because early detections can avoid greater health problems and further weakening effects. Since the wear of teeth determines their stability and lifetime in relation to the physiological load, an ultrasonic survey of any dimensional changes of the enamel layer and especially of the dentin wall thickness may be very helpful. However, an ultrasonographic diagnosis requires first to determine the anisotropic human tooth properties at clinically relevant locations and to simulate wave propagation phenomena in inhomogeneous tooth models with proper dimensions. The first article of a series that provides modular data of mineralized tissues in human teeth at the cemento-enamel junction (CEJ) deals with an ultrasonic method for measuring the asymmetry of dimensional characteristics of extracted human teeth and their ultrasonic path lengths (UPL). Heavily attenuating tooth halves were investigated with respect to the symmetry of normal and inclined oppositely directed radial ultrasonic paths. The measured UPLs ranged from 1.2 mm to 4.4 mm. The relative difference in inclined UPLs between the left and the right tooth halves reaches almost 30%. This reveals a large asymmetry. The mean difference of angles that represent fastest path lengths was 2.2+/-8.1 degrees, which indicates large asymmetry and anisotropy. Several aspects, which are required for a proper integration of asymmetric data into models designed for medical element engineering and simulation (MEES), are discussed.

Algorithms↗