Evaluation of different irrigation solutions and activation methods on removing calcium hydroxide.

BACKGROUND/PURPOSE: Dual Rinse HEDP is a soft chelator which can be used simultaneously with sodium hypochlorite (NaOCl). The aim of this study is to evaluate the efficacy of Dual Rinse HEDP with different irrigation systems on removing calcium hydroxide [Ca(OH)2]. MATERIALS AND METHODS: Eighty maxillary central incisor teeth were shaped and a standard groove on the apical third of the root canal surface was prepared. The root canals were filled with Ca(OH)2. Samples were divided into two groups according to the solution and these two groups were divided into three subgroups based on the activation technique. In group 1 (n = 10) Ca(OH)2 was removed using conventional irrigation with NaOCl whereas in group 2 (n = 10) conventional irrigation with NaOCl - Dual Rinse HEDP mixture was used. Group 3 (n = 15) and group 4 (n = 15) received sonic activation with the same irrigants as groups 1 and 2 respectively. In group 5 (n = 15) passive ultrasonic irrigation (PUI) was used with NaOCl while in group 6 (n = 15) the irrigant was the mixture. The amount of remaining Ca(OH)2 in the artificial grooves were evaluated under a light microscope. RESULTS: None of the procedures managed to completely remove the Ca(OH)2 from artificial grooves. There was no significant difference between the groups (p = 0.053). The scores were significantly lower in PUI group compared to the other techniques between NaOCl groups (p = 0.021). CONCLUSION: Dual Rinse HEDP does not make a difference on elimination of Ca(OH)2. PUI is more efficient than both methods when NaOCl solution is used.

Evaluation of complex mesiobuccal root anatomy in maxillary first molar teeth / Evaluación de la anatomía de la raíz mesiobucal compleja en los primeros dientes molares maxilares

The objective of this study was to investigate the complex anatomy of mesiobuccal roots, supporting and complementing commonly applied clearing technique, using access cavity modification and the pulpal groove deepening method. Three hundred and ninety eight extracted intact human maxillary first molars were included in this study. Firstly, modified rhomboidal shape access cavities were prepared then, the developmental groove between the mesiobuccal and the palatal canals was deepened 1 mm with a round slow speed bur. Indian ink was injected into both the canal orifices of mesiobuccal roots and into the groove between mesiobuccal and palatal canals, using a 22 gauge syringe. Then the clearing technique was applied. The incidence of one canal was 30.90 %, two canals was 62.07 %, three canals was 7.03 %. In twenty five (6.28 %) of the mesiobuccal roots, 8 root canal types, which are not included in Vertucci's classification, were seen. All these root canal types had three root canals. The establishment of adequate access and deepening of the pulp chamber floor increased the probability of locating the third canal in the mesiobuccal root of maxillary first molars.

El objetivo de este estudio fue investigar la compleja anatomía de las raíces mesiovestibulares, apoyando y complementando la técnica de limpieza aplicada comúnmente, usando la modificación de la cavidad de acceso y el método de profundización del surco pulpar. En este estudio se incluyeron 398 primeros molares maxilares, extraídos intactos. Se prepararon las cavidades de acceso con la forma romboidal modificada, el surco de desarrollo entre los conductos mesiovestibular y palatino se profundizó 1 mm con una fresa redonda de velocidad lenta. Se inyectó tinta china en los forámenes del canal de las raíces mesiovestibulares y en el surco entre los conductos mesiovestibular y palatino utilizando una jeringa de calibre 22. Luego se aplicó la técnica de limpieza. La incidencia de un canal fue del 30,90 %, dos canales del 62,07 % y tres canales del 7,03 %. En 25 casos (6,28 %) de las raíces mesiobucales, se observaron 8 tipos de conductos radiculares, que no están incluidos en la clasificación de Vertucci. Todos estos tipos de conductos tenían tres conductos radiculares. La determinación de un acceso adecuado y la profundización del piso de la cámara de pulpa aumentó la probabilidad de localizar el tercer canal en la raíz mesiovestibular de los primeros molares superiores.

Crack formation on resected root surfaces subjected to conventional, ultrasonic, and laser root-end cavity preparation.

OBJECTIVE: The aim of this study was to evaluate cracks on root ends following resection and cavity preparation with a laser and two established techniques. BACKGROUND DATA: If root canal treatment of a tooth fails, an apicoectomy operation may be indicated. Three millimeters of the root tip is resected and a cavity of similar depth with parallel walls is cut to receive a root-end filling. MATERIALS AND METHODS: Sixty extracted human maxillary anterior teeth were used. Their root canals were prepared with rotary instruments, and they were filled with gutta-percha. Twenty teeth were resected with tungsten carbide fissure burs, and their root-end cavities cut with tungsten carbide round burs at a slow speed (Group 1). The other 40 teeth were resected with an Er:YAG laser, and root-end cavities were made with the same laser (Group 2), or with an ultrasonically-powered zirconium nitride coated retrotip (Group 3). The number and types of cracks on the resected surfaces were assessed using a stereomicroscope before and after cavity preparation. RESULTS: Cracking was not significantly different between the more conventional group and the laser groups after resections (p>0.05) or following cavity preparation (p>0.05). CONCLUSIONS: In this in vitro study, the laser resection and root-end preparation technique did not influence the number or type of cracks formed on the root surfaces.

Accuracy of the Dentaport ZX apex locator for working length determination when retreating molar root canals.

The aim of this study was to evaluate the accuracy of the Dentaport ZX apex locator for working length determination during root canal retreatment of mandibular molars. Fifteen extracted mandibular first molars with separate mesial canals and apical foraminae and one distal canal were selected. The mesiobuccal and distal canals were investigated; the length with the file tip at the major diameter was defined as the tooth length (TL). The canals were prepared with ProTaper files to 1 mm short of this and filled with gutta-percha and AH Plus sealer. One week later, the root fillings were removed using ProTaper retreatment files. Tooth length was remeasured and recorded as the retreatment tooth length (RTL). Then electronic measurements were taken at the major (electronic apex locator (EAL) major) and minor (EAL minor) foraminae as suggested by the instrument display. These lengths were compared with RTL and measurements 0.5 and 1 mm short of this distance. For both canals, no significant difference was found between RTL and EAL major, and 0.5 mm short of RTL and EAL minor (P > 0.05). There were significant differences found between all other readings. The Dentaport ZX could not detect the minor foramen accurately but was able to indicate the major foramen in molars undergoing a root canal retreatment procedure.

Evaluation of two different root-end cavity preparation techniques: A scanning electron microscope study.

OBJECTIVE: In this study, we aimed to evaluate and compare the dentinal walls of root-end cavities for the presence of cracks after cavity preparation using US retrotips and Er: YAG laser. MATERIALS AND METHODS: Fifty single-rooted teeth were prepared by Protaper NiTi rotary system and obturated by lateral condensation. Three milimeters of root-end was resected. Twenty teeth were prepared with US retrotip (Group 1), 20 teeth with Er: YAG laser (Group 2), and 10 teeth without retropreparation (control group). The root-end surfaces were examined under a scanning electron microscope (SEM). Then the cracks of the resected root surfaces were evaluated on microphotographs. RESULTS: No statistically significant difference was detected between US Group and Laser Group for complete, incomplete, intradentinal, and total number of cracks (P = 0.47, P = 0.80, P = 0.69, P = 0.869, respectively). CONCLUSION: Statistical analysis revealed no significant effect of retropreparation technique on the development of apical cracks (P > 0.05).

Sealing efficiency of BeeFill 2in1 and System B/Obtura II versus single-cone and cold lateral compaction techniques.

OBJECTIVE: The objective of this study was to investigate the sealing properties of 2 warm vertical compaction techniques (BeeFill 2in1, System B/Obtura II) in comparison with single-cone and cold laterally compacted gutta-percha. STUDY DESIGN: The root canals of single-rooted human teeth were prepared by using Mtwo rotary files and divided into 4 groups (n = 10/group) with respect to the filling technique tested: Group 1, cold laterally compacted gutta-percha + AH-26; Group 2, single-cone tapered Mtwo gutta-percha + AH-26; Group 3, System B/ObturaII + AH-26; Group 4, BeeFill 2in1 + 2seal. The leakage of specimens was measured using a fluid-filtration method after 1 and 2 weeks. The data were analyzed statistically with 2-way repeated measures ANOVA (P = .05). RESULTS: After 1 week, the System B/Obtura II group showed the greatest amount of leakage(P < .05) compared with the other test groups that had similar levels of fluid conductance(P < .05). By the end of the second week, the BeeFill group yielded the greatest amount of leakage (P < .05). Compared with their 1-week values, the fluid conductance of all test groups decreased significantly (P < .05). CONCLUSION: The apical sealing efficiency of System B/Obtura II and BeeFill were inferior to the other obturation techniques after 2-week fluid conductance testing in vitro.

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.

Endodontic treatment of unusual central incisors.

This report presents an endodontic therapy in an unusual case of a patient who had wide crowns of both permanent maxillary central incisors. The right maxillary central incisor had two separate canals on a fused root and the left had a large root canal within one root.