Comparison of fracture resistance of simulated immature teeth with an open apex using Biodentine and composite resin: An in vitro study.

AIM: To evaluate the fracture resistance in simulated immature teeth that had been backfilled using composite resin and Biodentine after using Biodentine as an apical plug material immediately and after 3 months of aging. MATERIALS AND METHODS: Sixty extracted human maxillary central incisors were simulated in an immature open apex. The roots of all the specimens were then standardized to a length of 10 mm and canals were instrumented to obtain the radicular dentin thickness around 1.5 mm. All the specimens were then randomly divided into three groups of twenty teeth each. Group I (control) - 4 mm apical plug of Biodentine backfilled with thermoplasticized gutta-percha. Group II - 4 mm apical plug of Biodentine and then backfilled with ParaCore. Group III - completely filled with Biodentine. Ten samples from each group were randomly divided into two subgroups. In subgroup A: Specimens were stored for 1 week. In subgroup B: Specimens were stored in phosphate-buffered saline solution for 3 months and were subjected to universal testing machine. Statistical analysis was done using one-way analysis. RESULTS: No significant difference in fracture resistance between the groups was observed when tested immediately. After 3 months of aging, only Biodentine group showed a significant reduction in fracture resistance without significant reduction with other two groups. CONCLUSION: Biodentine group has shown a drastic reduction in fracture resistance after 3 months of aging, and hence cannot be recommended as a reinforcement material in immature teeth with thin dentin walls.

Comparison of third generation versus fourth generation electronic apex locators in detecting apical constriction: An in vivo study.

AIM: The aim of this in vivo study was to compare the accuracy of Root ZX and Raypex 5 in detecting minor diameter in human permanent single-rooted teeth. MATERIALS AND METHODS: Thirty-one patients with completely formed single-rooted permanent teeth indicated for extraction were selected for the study. Crown was flattened for stable reference point and access cavity prepared. Working length was determined with both apex locators. A 15 K file adjusted to that reading was placed in the root canal and stabilized with cement. The tooth was then extracted atraumatically. Following extraction apical 4 mm of root was shaved. The position of the minor diameter in relation to the anatomic apex was recorded for each tooth under stereomicroscope at ×10. The efficiency of two electronic apex locators to determine the minor diameter was statistically analyzed using paired sample t-test. RESULTS: The minor diameter was located within the limits of ±0.5 mm in 96.6% of the samples with the Root ZX and 93.2% of the samples with Raypex 5. The paired sample t-test showed no significant difference. CONCLUSION: On analyzing the results of our study it can be concluded that Raypex 5 was as effective as Root ZX in determining the minor diameter.

Differentiation of isolated and characterized human dental pulp stem cells and stem cells from human exfoliated deciduous teeth: An in vitro study.

AIMS AND OBJECTIVES: Isolation, characterization and differentiation of dental pulp stem cells (DPSCs) and stem cells from exfoliated human deciduous teeth (SHED). METHODS: The pulp tissue was digested in collagenase and cultured in DMEM Dulbecco's Modified Eagle's Media). The stem cells were identified and isolated. Surface characterization of cells was done with flow cytometer using surface markers. An immuno cytochemistry analysis was done. Differentiation potential was analyzed using various differentiation markers. RESULTS: Flow cytometry analyses for various CD markers showed similar results for both DPSCs and SHED. The cells showed positive expression for pluripotent, ectodermal and mesodermal markers. Cells differentiated into osteoblasts and adipocytes. CONCLUSION: The study demonstrated that stem cells existed in deciduous and permanent pulp tissue. The stem cells present in pulp tissue can be isolated, cultivated and expanded in vitro. Both DPSCs and SHED show almost a similar expression pattern profile for variety of antigens tested.

Chemical analysis of dentin surfaces after Carisolv treatment.

AIMS AND OBJECTIVES: This study was done to characterize the surface chemistry after caries excavation with burs and Carisolv 2, by analyzing the relative amounts of organic and inorganic content, and also to analyze the penetration of the adhesive after etching and bonding using Micro Raman spectroscopy. MATERIALS AND METHODS: Twenty extracted molars with caries were distributed into the following groups and treated accordingly. Group 1-excavation with bur (10 teeth), and Group 2-excavation using Carisolv 2 (10 teeth). RESULTS AND CONCLUSION: Spectroscopic analysis showed that there was no significant difference in the chemical composition of the tooth between the groups after excavation (P > 0.05) either with bur or with Carisolv. The penetration of the dentin bonding resin in all samples of the Carisolv group was up to 15mum, whereas, in the bur group it was upto 10mum in few samples. Scanning Electron Microscopic analysis showed the surfaces of the Carisolv-treated dentin to be free of the smear layer, with open tubules, whereas, the dentin surfaces of the bur group showed surfaces covered with a smear layer. In the Carislov group the resin tags were found comparatively deeper than in the bur excavation group. In both the groups the integrity of the remaining dentin surfaces were maintained chemically and morphologically.