Influence of access cavity design on root canal instrumentation efficacy in molars - An in vitro study.

Background: Several designs of access cavity have been evolved in the recent past with the concept of minimal tooth tissue removal which would improve the root canal treated teeth fracture resistance. Aim: To investigate the effect of conservative design access cavity during the instrumentation of maxillary molar root canals. Materials and Methods: Eighty noncarious maxillary molars were assigned to the traditional and conservative access groups (n = 40 each). After designated access preparations, the teeth were immersed in Lugols's solution for staining the pulp tissue. Root canal instrumentation was performed with TruNatomy file system. Pre- and postinstrumentation nano-computed tomography (CT) images were taken and reconstructed using CT-An software. Root canals volumetric analysis was done with CT-Vol software. The analysis of the data was dealt with Shapiro-Wilk test and independent t-test. Results: The volume of pulp canal space before and after instrumentation changed significantly between the traditional and conservative access design groups, according to an independent t-test. In comparison, the mean volume of dentin removed was much larger in the TAC group (P = 0.0016). The independent t-test manifests difference significantly between traditional endodontic access cavity (TAC) and conservative access cavity (CAC) with percentage of unprepared canal walls. The mean percentage of unprepared area was significantly lesser in TAC group as compared to CAC group (P = 0.0022). Conclusion: The volume of dentin removed was greater in TAC than with the CAC design. The amount of untouched canal wall area was significantly higher in conservative access design than with the traditional access design group.

Micro-push-out bond strength of mineral­based root canal sealer in canals with different tapers / Fuerza de unión por micro-expulsión del sellador de conductos radiculares a base de minerales en conductos con diferentes ahusamientos

Objective: The aim of this study was to assess the micro-push-out bond strength of a mineral-based root canal sealer, BioRoot RCS in canals prepared by K3XF rotary systems of two different tapers. Material and Methods: Eighty caries free maxillary central incisors were used in this study. The samples were allocated into 4 groups (n=20) according to the root canal sealer and taper of the rotary instruments. The samples were obturated using single cone obturation technique. From each root 1mm thick slices at coronal, middle and apical thirds were collected using hard tissue microtome under continuous water coolant. Push-out tests were done for these sections using a Universal testing machine (INSTRON 8801) at a crosshead speed of 1mm/min. One-way analysis of variance (ANOVA) was used to compare the bond strengths within groups and Tukey's multiple post hoc analysis was used for pair-wise comparison of bond strengths. Results: AH Plus exhibited higher micro-push-out bond strength than BioRootRCS though they did not differ significantly (p>0.05). Preparation of root canals with 6% taper rotary instruments showed higher bond strength than 4% though they did not differ significantly (p>0.05). Conclusion: There was no significant difference between micro-push-out bond strength values of BioRoot RCS and AH Plus. The bond strength values were high in 6% taper canals than 4% canals though the difference was not significant statistically.

Objetivo: El objetivo de este estudio fue evaluar la fuerza de unión por micro-expulsión de un sellador de conductos radiculares de base mineral, BioRoot RCS, en conductos preparados por sistemas rotativos K3XF con dos conos diferentes. Material y Métodos: En este estudio se utilizaron 80 incisivos centrales superiores libres de caries. Las muestras se distribuyeron en cuatro grupos (n = 20) de acuerdo al sellador del conducto radicular y al cono de los instrumentos rotativos. Las muestras se obturaron mediante la técnica de obturación de un solo cono. De cada raíz se recogieron rodajas de 1 mm de grosor en los tercios coronal, medio y apical utilizando un micrótomo de tejido duro con refrigeración continua por agua. Posteriormente, se realizó una prueba de expulsión para estas secciones utilizando una máquina de prueba universal (INSTRON 8801) a una velocidad del cabezal transversal de 1mm/min. Se utilizó el análisis de varianza unidireccional (ANOVA) para comparar las resistencias de la unión dentro de los grupos y el análisis post hoc multiple de Tukey se utilizó para la comparación por pares de las resistencias de la unión. Resultados: AH Plus exhibió una fuerza de unión de micro-expulsión más alta que BioRootRCS, aunque no difirieron significativamente (p>0,05). La preparación de los conductos radiculares con instrumentos rotativos ahusados al 6% mostró una fuerza de unión superior al 4%, aunque no difirieron significativamente (p>0,05). Conclusión: No hubo diferencias significativas entre los valores de fuerza de unión de micro-expulsión de BioRoot RCS y AH Plus. Los valores de la fuerza de unión fueron más altos en canales cónicos al 6% que en canales al 4%, aunque la diferencia no fue significativa estadísticamente.

Surface quality and color stability of posterior composites in acidic beverages.

CONTEXT: Consumption of acidic beverages has been reported to alter the physical and esthetic properties of resin composites, which in turn can affect clinical success. AIMS: This study aimed to evaluate the effect of acidic beverages on surface roughness and color stability of Filtek™ Bulk-Fill posterior restorative composite in comparison with Filtek P60 posterior restorative composite. SETTINGS AND DESIGN: Ninety composite discs were used for surface change analysis and another ninety were used for color change analysis. MATERIALS AND METHODS: Ninety Filtek P60 and Filtek Bulk-Fill composite discs were fabricated and divided into three subgroups according to the solutions - artificial saliva (control group), orange juice, and Coca-Cola® (test groups). The samples were immersed in each beverage for 10 min each day for 56 days. To measure the surface roughness, a profilometer was used, and the surface was qualitatively analyzed using a scanning electron microscope. A reflectance spectrophotometer was used for assessing the color change. STATISTICAL ANALYSIS USED: Two-way analysis of variance was used to compare the surface alteration and color change values between the two composite groups and their respective three subgroups. Tukey's multiple post hoc test was performed for pair-wise comparison. RESULTS: Filtek P60 had exhibited higher color change than Filtek Bulk-Fill in all immersion solutions. Coca-Cola resulted in highest staining in both the composites. CONCLUSIONS: The surface roughness and color change of both composites increased significantly in acidic beverages and more in Coca-Cola. Bulk-fill exhibited better surface quality and color stability than P60.

Endodontic management of contralateral mandibular first molars with six root canals.

The knowledge of variations in root canal morphology is essential for a successful endodontic outcome. Contralateral mandibular molar with six root canals is a rare entity. Root canal treatment of mandibular molars with aberrant canal configuration can be diagnostically and technically challenging. While dealing with variant mandibular molars, mishaps may happen. This case report describes variations in contralateral mandibular molars and also an endodontic mishap while managing them.

Validity of bond strength tests: A critical review-Part II.

BACKGROUND: Macro-bond strength tests resulted in cohesive failures and overestimation of bond strengths. To reduce the flaws, micro-bond strength tests were introduced. They are the most commonly used bond-strength tests. OBJECTIVE: Thus the objective of this review is to critically review the reliability of micro-bond strength tests used to evaluate resin-tooth interface. DATA COLLECTION: Relevant articles published between January 1994 and July 2013 were collected from Pubmed database, Google scholar and hand searched journals of Conservative Dentistry, Endodontics and Dental materials. DATA SYNTHESIS: Variables that influence the test outcome are categorized into substrate related factors, factors related to specimen properties, specimen preparation and test methodology. Impact of these variables on the test outcome is critically analyzed. CONCLUSION: Micro-bond tests are more reliable than macro-bond tests. However, no standard format exists for reporting the bond strength tests which could lead to misinterpretation of the data and bonding abilities of adhesives.

Validity of bond strength tests: A critical review: Part I.

Adhesive systems are selected based on their bond strengths achieved while testing in laboratories. These bond strengths can predict the longevity of a restoration to some extent. There were several discrepancies in the reported bond strengths. To critically review the reliability of macro-bond strength tests used to evaluate resin-tooth interface. Relevant literature published between January 1983 and May 2013 was collected from PubMed database, Google scholar, and hand-searched journals of Conservative Dentistry, Endodontics and Dental materials. Variables that influence the test outcome are categorized into substrate-related factors, factors related to specimen properties, preparation of specimens, and test methodology. Impact of these variables on the test outcome is critically analyzed. There is lack of a standard format for reporting the bond strength tests, which could lead to misinterpretation of the data and bonding abilities of adhesives.

Autotransplantation of mandibular third molar: a case report.

Autogenous transplantation is a feasible, fast, and economical option for the treatment of nonsalvageable teeth when a suitable donor tooth is available. This paper presents successful autotransplantation of a mature mandibular left third molar (38) without anatomical variances is used to replace a mandibular left second molar (37). The mandibular second molar was nonrestorable due to extensive root caries and resorption of distal root. After extraction of mandibular second and third molars, root canal therapy was done for the third molar extraorally, and the tooth was reimplanted into the extracted socket of second molar site. After one year, clinical and radiographic examination revealed satisfactory outcome with no signs or symptoms suggestive of pathology. In selected cases, autogenous tooth transplantation, even after complete root formation of the donor tooth, may be considered as a practical treatment alternative to conventional prosthetic rehabilitation or implant treatment.