Evaluation of Microcracks formed During Root Canal Preparation by Different File Systems Using Micro-computed Tomography: An In Vitro Study.

AIM: The purpose of this study was to evaluate and compare the incidence of dentinal microcracks after instrumentation with various types of nickel-titanium (NiTi) files in rotary and reciprocating motion. MATERIALS AND METHODS: Fifty human extracted mandibular molars were taken and divided into five groups (n = ten teeth per group). Group I included ProTaper Gold, group II included OneShape, group III included WaveOne Gold, group IV included Reciproc, and group V included hand K files. The teeth were desectioned at the cemento-enamel junction (CEJ) and dentinal microcracks were observed under Micro-computed tomography. Postoperative Micro-computed tomography analysis of the samples was conducted to inspect cracks in the images obtained before and after preparation. RESULT: Results confirmed that there was a statistically significant difference between the study groups (p <0.05). The highest percentage of microcracks was seen in ProTaper Gold followed by OneShape. WaveOne Gold and Reciproc showed closely similar percentage of microcracks followed by hand K files that showed the least. CONCLUSION: Both rotary file systems showed higher number of microcracks than reciprocating file systems. Hand K files showed least microcracks formation among all studied groups. CLINICAL SIGNIFICANCE: Among all the tested methods and systems, hand K files demonstrated least incidence of dentinal microcracks. However, these hand K files systems are not advanced and have certain practical limitations. Reciprocating systems usually exhibits clinically acceptable microcracks therefore they may be judiciously utilized. Rotary file systems showed excellent biomechanical outcomes with redundant microcrack formation. Hence, precise selection of a particular system must be solely dependent upon the clinical decision making and circumstantial requirements.

Anticancer Effects of Extracts from Three Different Chokeberry Species.

Colon cancer risk appears to be lowered by consumption of a diet rich in fruits and vegetables. Chokeberries are rich in phytochemicals that may act as potent anticancer agents. Phytochemicals that are particularly abundant in chokeberries include anthocyanins and phenolic acids. In this study, we compared the growth inhibitory activity of three chokeberry extracts in HT-29 human colon cancer cells. The three extracts tested were derived from Aronia arbutifolia (red), Aronia prunifolia (purple), and Aronia melanocarpa (black). Cells were incubated with either red, purple, or black chokeberry extracts and cell viability was quantified using the thiazolyl blue tetrazolium bromide (MTT) assay. The black chokeberry extract had the greatest effect in reducing cell proliferation. The extracts were also characterized for total phenols (Folin-Ciocalteu assay), total antioxidant activity (oxygen radical absorbance capacity assay), and levels of bioactive phenolic acids (high-performance liquid chromatography). The growth inhibitory activities of the extracts correlated well with total phenolic content, antioxidant activity, and levels of caffeic and chlorogenic acids. The black chokeberry extract had the greatest level of total phenols, antioxidant activity, and individual phenolic acids. This research suggests that the phenolic profile of foods such as chokeberries can help determine their cancer cell growth inhibitory activity.