Sealing properties of three luting agents used for complete cast crowns: a bacterial leakage study.

OBJECTIVE: To assess the sealing properties of three different luting materials used for cementation of full cast crowns on extracted human premolars. METHODS: Thirty noncarious human premolars were prepared in a standardized fashion for full cast crown restorations. All margins were placed in dentin. After impressions of the preparations, stone dies were fabricated on which copings were waxed, which were cast in type III alloy using standardized laboratory methods. Teeth were randomly assigned to three groups of 10 samples each (n=10), for which the following cements were used: 1) a resin-modified glass ionomer cement, Rely X Luting Plus (3M ESPE, St Paul, MN, USA); 2) a self-adhesive resin cement, Maxcem Elite (Kerr Corporation, Orange, CA, USA); and 3) a glass ionomer cement, Ketac Cem (3M ESPE), the latter used as control. After cementation the samples were allowed to bench-set for 10 minutes, stored in water at 37°C, subjected to thermal cycling (2000×, between 5°C and 55°C, dwell time 35 seconds), and then stored in sterile phosphate buffer for seven days at 37°C. Subsequently, the occlusal surface was carefully reduced until the dentin was exposed. Finishing on wet sand paper removed the gold flash caused by grinding. After sterilization, the specimens were subjected to bacterial microleakage in a dual chamber apparatus for 60 days. Bacterial leakage was checked daily. Data were analyzed using the Kaplan-Meier survival test. Significant pairwise differences were analyzed using the log-rank test followed by Fisher exact test at a p<0.05 level of significance. RESULTS: Rely X Luting Plus showed the lowest microleakage scores, which statistically differed significantly from Maxcem Elite and Ketac Cem (p<0.05). CONCLUSIONS: Rely X Luting Plus cement displayed significantly lower microleakage scores than a self-adhesive resin-based and conventional glass ionomer cement.

Retreatment efficacy of hand versus automated instrumentation in oval-shaped root canals: an ex vivo study.

AIM: To compare the efficacy of hand versus automated instrumentation when retreating oval-shaped root canals. METHODOLOGY: Sixty human premolars with single oval canals were instrumented and filled with gutta-percha and sealer and divided into three groups (n = 20)--group 1: ProFile .04 taper rotary instruments; group 2: Anatomic Endodontic Technology (AET), and group 3: manual instrumentation with Hedström files. The teeth were split longitudinally and gutta-percha/sealer remnants in the coronal, middle and apical thirds were assessed with light microscopy. The mean percentage of gutta-percha/sealer remnants for each group was calculated and statistically analysed for significance using an ANOVA repeated measures (P < 0.001) and Tukey's multiple comparison test. The time required for retreatment was analysed using a one-way ANOVA and Tukey's test (P < 0.001). RESULTS: Overall, 10-18% of the canal walls were covered with gutta-percha/sealer remnants after preparation using any technique. Statistical analysis demonstrated that the mean values for remnants of filling material in the ProFile group were significantly higher than for the other groups (P < 0.001), except in the apical third where no significant difference occurred. In all groups, the mean values in the middle third were higher than the coronal and apical thirds. The retreatment time for ProFile and AET was significantly shorter compared to manual instrumentation with Hedström files (P < 0.001). CONCLUSIONS: Under the experimental conditions, AET instruments and manual instrumentation with Hedström files resulted in cleaner canals. However, completely clean root canal walls were not produced with any of the techniques investigated.

Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic study.

AIM: To compare in vitro the cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation. METHODOLOGY: Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at x200 and x400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 mum square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal-Wallis nonparametric anova and Dunn's tests. RESULTS: At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups. CONCLUSIONS: Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated.

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.

Five canals in a mandibular second premolar.

A case of conservative endodontic therapy for a mandibular second premolar with five root canals is described. A thorough knowledge of the root canal anatomy, careful interpretation of the radiographs, and access cavity modifications are essentials for enhancing intracanal procedures.

Endodontic management of a mandibular third molar fused with a fourth molar.

CASE REPORT: Developmental anomalies in permanent molars frequently require surgical intervention. A case of a mandibular third molar fused with a fourth molar which was successfully treated with conservative endodontic therapy is reported.

Clinical experience of root canal filling by ultrasonic condensation of gutta-percha.

Ninety human teeth with a total of 181 prepared root canals were filled with the use of ultrasonically energized spreaders as an aid for lateral condensation of gutta-percha cones. The results were evaluated on the basis of clinical and radiographic criteria. Adequate fillings were found in 93% of the canals and the overall success rate was 93%. All of the recalled patients were clinically comfortable.

Endodontic therapy in a fused mandibular molar.

This case report describes the endodontic management of fusion involving a mandibular third molar and a fourth molar (distomolar).

Delayed apical healing after apexification treatment of non-vital immature tooth: a case report.

We report the endodontic treatment of a non-vital permanent immature tooth in which unexpected complications such as exacerbation of apical periodontitis followed by external root resorption occurred after that the initial stages of the healing process were clinically and radiographically evident. After continued treatment stable repair was obtained.

Mental nerve paresthesia associated with an amalgam filling: a case report.

We present a case report in which a mental nerve paresthesia occurred in connection with an amalgam filling placed in direct contact with the pulp of a mandibular first molar. The main evidence for amalgam being the dominant etiological factor was the positive epicutaneous patch testing response to the components of the amalgam alloy, and the total remission of symptoms without further clinical complications after removal of the amalgam filling and subsequent endodontic therapy.

Detection and measurement of endodontic root perforations using a newly designed apex-locating handpiece.

Access openings and lateral root perforations were prepared in 40 single-rooted extracted teeth. The distance to the perforations was measured visually and then with the Tri Auto ZX. The electronic device was used first in its apex-locating function and then in conjunction with its automatic reverse mechanism. On average, the electronically measured length was slightly shorter than the visually measured length (P < 0.05). When the automatic reverse mechanism was used, the values registered were either consistent with or slightly different (+/- 0.5 mm) from the electronically measured length (P > 0.05). The results of this study revealed that the Tri Auto ZX detected and measured endodontic root perforations within a range of clinically acceptable variations.

Endodontic therapy in a maxillary second molar with three buccal roots.

In this study, we report a case of a four-rooted maxillary second molar in which three well-separated buccal roots were located. This case demonstrated that even though it is not common, an extra root containing an independent root canal may occur.

A case of severe vestibular root angulation.

In this article, we describe the appearance and management of an impacted permanent tooth with severe vestibular root angulation. In addition, the possible origin of this type of root malformation as well as some of their epidemiologic aspects are discussed.

Sealing properties of a new epoxy resin-based root-canal sealer.

In this study a new epoxy-resin-based endodontic sealer, AH Plus, was tested in vitro for apical leakage. The conventional sealer AH26, for which information is already available, was used as the control. The root canals of 72 single-rooted teeth were prepared biomechanically using a stepback technique before lateral condensation of gutta-percha with one of the two sealers. Teeth were immersed in 5% methylene blue dye for 2, 4 or 10 days. The roots were split longitudinally so that the extent of dye penetration could be measured with a stereomicroscope. The mean extent at 2 days was 0.4 mm for AH26 and 1.4 mm for AH Plus. Neither material produced a complete apical seal and leakage increased with the duration of immersion in dye. The differences between observation periods as well as between materials with respect to dye penetration were statistically significant ANOVA, (P < 0.005).

Compatibility between standardized endodontic finger spreaders and accessory gutta-percha cones.

Twenty samples of each size designation of finger spreaders and accessory gutta-percha cones were randomly selected from a proprietary standardized system currently used for lateral condensation procedures. Their diameters were measured with a calliper and their morphological variations at the areas of their apical thirds were analyzed with the scanning electron microscope. Results of the measurements indicated that there were high degrees of variation between all spreaders and their corresponding accessory gutta-percha cones (p < 0.001). SEM examination showed the presence of many morphologic irregularities and lack of uniformity between spreaders and cones of the same size. Our results emphasize the need for more precise criteria to fulfill the requirements of standardization by the manufacturer to provide an accurate method for root canal obturation.

Comparison of three instrumentation techniques in the preparation of simulated curved root canals.

Forty-five acrylic blocks with simulated curved canals were divided into three groups of 15 blocks each. In group 1 the canals were instrumented with ultrasonically energized K-files (UEF) using a piezoelectric ultrasonic device. In group 2 the canals were prepared with ProFile 0.04 Taper Series 29 Rotary Instruments (PRI) in conjunction with a low-speed high torque handpiece. In group 3 (control) the canals were hand instrumented (HI) with conventional K-type files using a standard push-pull circumferential technique. The efficiency of these techniques for preparing the simulated canals were compared by measuring the amount of transportation of the prepared canals at different levels from the working length using a double exposure photographic technique. A statistical analysis was used to indicate any significant difference among groups. The results showed that the use of PRI provided well-centred and more tapered preparations. Conversely, the use of UEF and HI resulted in frequent alteration of the original curvature, showing transportation at different levels from the working length.

Endodontic management of mandibular lateral incisor fused with supernumerary tooth.

In this article we report a case of a mandibular lateral incisor in which 3 separate root canals were located. Clinical and radiographic examinations suggested that fusion had occurred between the mandibular incisor and a supernumerary tooth. The endodontic management of the tooth is described, and repair of an apical periodontitis had occurred after 9 months.

Effectiveness of nickel-titanium files for preparing curved root canals.

In this study, the effect of 2 different endodontic files on the final shape of curved root canals of extracted single rooted teeth were examined in the scanning electron microscope. The instruments tested were a newly designed nickel-titanium endodontic file and a conventional K-type file. The files were used with in and out linear movements with a circumferential motion starting with a size 15 file. Final preparation of the apical thirds of the canals was performed with a size 35 file. Shaping effectiveness of the tested instruments was evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging. Our observations revealed that more centered and tapered preparations were obtained with the use of the nickel-titanium files than with the conventional K-type files.

Cleaning of endodontic instruments before use.

In this study, 120 new K-files and Hedström files from 3 different manufacturers were examined for surface debris with the scanning electron microscope. The instruments were examined immediately upon removal from their original packages. A second examination of the instruments was performed after they were cleansed in an ultrasonic bath. None of the studied instruments were free of metallic spurs or foreign particles as received from the manufacturers. The ultrasonic bath used together with a cleanser solution appeared to be an effective method to minimize the surface impurities from the manufacturing process prior to use in patients.

Effectiveness of two different methods for preparing curved root canals.

In this study, the effect of using two different methods for preparing curved root canals of extracted, single-rooted teeth were analyzed with the scanning electron microscope. The instrumentation systems tested were the Canal Master and a standard circumferential filing technique in which conventional K-files were used. Shaping effectiveness was qualitatively evaluated in terms of respect for conservation of the apical constriction and the presence or absence of ledging, specially in the apical third of the root canals. As a result of our observations, it appeared that the Canal Master instrumentation technique provided well-centered and tapered preparations. Conversely, the use of conventional K-files with a standard circumferential filing technique resulted in frequent alterations of the initial pattern of the root canals, showing transportation of the apical foramen and ledge formation.