ABSTRACT
OBJECTIVE: Endodontic sealer should adhere to both dentin and the core filling material but the moisture conditions of the canals affect the adhesive properties of the sealer. An ideal sealer with perfect moisture conditions will lead to greater strength of the restored tooth, which may provide greater resistance to tooth fracture and clinical longevity of an endodontically treated tooth. The aim of this study was to evaluate the effect of moisture conditions on the push-out bond strength of three root canal sealers: AH Plus® (Dentsply-Tulsa Dental, Tulsa, OK), Epiphany (Pentron Clinical Technologies, Wallingford, CT), and GuttaFlow (Coltene/Whaledent, Altstatten, Switzerland). MATERIALS AND METHODS: A total of 120 single-rooted, non-carious teeth were collected for the study and were stored in normal saline. The root canals were prepared using step-back technique. Teeth were divided into four groups based on type of drying procedure used and further subdivided into three subgroups based on the type of sealer used. The samples were cut horizontally to produce slices and then tested for push-out bond strength using Universal Testing Machine (Servo Series 50 kN; P S I Sales Private Limited, New Delhi, India). The specimens were examined for mode of fracture under magnification and the results were analyzed statistically. RESULTS: Distinctive moisture conditions for all sealers were observed and the highest strength of AH Plus® was evaluated under moist condition, Epiphany under dry condition, and GuttaFlow under normal condition, respectively. CONCLUSION: Distinctive moisture conditions affect the push-out bond strength of the sealers.
ABSTRACT
AIM: The aim of the study is to evaluate fracture resistance of nanocomposites with and without fiber reinforcement with different cavity designs used for obliquely fractured incisal edge restoration. MATERIALS AND METHODS: In the present study, 60 sound extracted maxillary central incisors were mounted on autopolymerizable acrylic resin up to the cementoenamel junction, out of which, 10 intact teeth were kept as control (group 1) and the remaining 50 samples were reduced incisally in an oblique manner up to 3 mm. All incisally reduced samples were divided into five groups (n = 10) based on the restoration techniques as follows: group 2 (conventional bevel), group 3 (single central palatal slot on the incisal edge), group 4 (single palatal slot with central 2 mm fiber), group 5 (two palatal slots on the incisal edge with a distance of 0.5 mm to 1 mm between them), and group 6 (two slots on the incisal edge with two 2 mm fibers). All samples were built incrementally with nanocomposites followed by finishing and polishing. All samples including control were then stored in distilled water before their fracture resistance was measured using a universal testing machine. Failure modes were visually examined and the results were subjected to statistical analysis. RESULTS: The mean fracture resistance among the experimental groups was observed, group 4 with single fiber in the central position had the highest (832.68 N) followed by group 3 (490.84 N), group 5 (446.175), and group 2 (270.1359), and the least in group 6 (223.443). The mean fracture resistance of group 4 is comparable to intact teeth, i.e., group 1 (1096.40). The mean of all samples was compared using the one-way Anova test, and it was found that there is statistically significant difference in fracture resistance among groups (p < 0.001**). CONCLUSION: Fibers certainly have the reinforcing effect and the position of fibers determines their reinforcing effects. A single central slot with fiber (Ribbond) showed maximum fracture resistance almost equivalent to natural teeth. Modifying conventional beveled cavity design with an additional slot in the center also increases the fractural strength of restoration. CLINICAL SIGNIFICANCE: Nanocomposites reinforced with single fiber in the central palatal slot used for restoring fractured incisors provide strength almost equivalent to natural teeth. In case when the fiber is not available for preparing a single palatal slot also, we can increase the fracture resistance.