Effect of mouthrinses on microhardness and wear of composite and compomer restoratives.

This study investigated the effect of commercially available mouthrinses on the microhardness and wear of composite (Esthet-X, Dentsply) and compomer (Dyract Posterior, Dentsply) restoratives. Fifty-four hardness and 36 wear specimens of each material were fabricated and stored in distilled water at 37 degrees C for two weeks. The specimens were then randomly divided into six equal groups and exposed to the following solutions for 24 hours at 37 degrees C: distilled water [WC] (control); Listerine Original [AP] (alcohol-containing essential oil/phenolic compound mouthrinse); Colgate Chloropharm [AC] (alcohol-containing chlorhexidine mouthrinse); Oral B Tooth & Gum Care [AF] (alcohol-containing fluoride mouthrinse); Oral B Tooth & Gum Care Alcohol Free [OF] (alcohol free fluoride mouthrinse) and Oral B Sensitive [PF] (phosphoric acid containing fluoride mouthrinse). After conditioning, the specimens were subjected to hardness testing using a digital microhardness tester (load = 500 gf; dwell time = 15 seconds) and wear testing with a reciprocal compression-sliding system (contact stress = 20 MPa). Wear depth was measured every 1,000 cycles up to 10,000 cycles using profilometry. Data was analyzed using ANOVA/Scheffe's test at significance level 0.05. Dyract was significantly softened by AP, while Esthet-X was significantly softened by AC and AP. The wear resistance of Dyract was significantly reduced after exposure to PF, while the wear resistance of Esthet-X was significantly reduced by AC. The effect of mouthrinses on hardness and wear was material dependent.

Salivary biomarkers associated with academic assessment stress among dental undergraduates.

This study aims to assess the difference in self-perceived stress before and after an academic assessment and its association with the marks scored and to study the association of salivary cortisol, Immunoglobulin A (IgA), and chromogranin A (CgA) with stress levels before and after the assessment. Thirty-one third-year dental undergraduates indicated how stressed they felt on a 5-point rating scale just prior to and immediately after a one-hour written test. Five-minute unstimulated whole saliva samples were also collected at those times to measure salivary cortisol, IgA, and CgA. Students rated significantly higher stress scores before (median [inter quartile range]: 3[1]), compared to after the test (2[2]) (p = 0.015). Higher cortisol levels (mean: 6.32 nmol/l) were observed before than after the exam (mean: 5.16 nmol/l) (p = 0.015). No significant differences were noted between the pre- and post-test saliva samples for salivary IgA and CgA levels. A negative correlation was seen between post-test stress scores and test marks (Spearman's r = -0.325, p = 0.07). Dental students perceived a higher level of stress prior to the test, which declined after that. Pre-test stress scores were associated with raised salivary cortisol, but not IgA or CgA. Students who perceived higher levels of stress after the test generally had poorer results.

Effects of professionally applied topical fluorides on surface hardness of composite-based restoratives.

This study investigated the effects of professionally applied topical fluorides on the surface hardness of a composite (Spectrum TPH), a compomer (DyractAP) and a giomer (Reactmer). Thirty specimens of each material were fabricated and stored in distilled water at 37 degrees C for one week. These specimens were then randomly divided into five groups of six and treated for 36 hours at 37 degrees C with one of the following: distilled water (control), 1.23% acidulated phosphate fluoride (APF) foam, 0.9% neutral foam, 1.23% APF gel and 0.4% stannous fluoride gel. The treated specimens were subsequently subjected to microhardness testing (load = 500 gf; dwell time = 15 seconds). Results were analyzed using ANOVA/Scheffe's test (p<0.05). The effects of topical fluoride application on surface hardness was material dependent. For all materials, treatment with APF gel and foam significantly reduced surface hardness when compared to the control. KHN values after exposure to APF gel were consistently the lowest and ranged from 4.53 to 15.97. Control KHN values were higher, ranging from 32.88 to 47.47. The surface hardness of the compomer was also significantly reduced after exposure to neutral foam. Therefore, the use of professionally applied topical fluorides, especially APF gel and foam, may be detrimental to the long-term durability of composite-based restoratives.