The effect of immediate dentin sealing with chlorhexidine pretreatment on the shear bond strength of dual-cure adhesive cement.

The purpose of this in vitro study was to evaluate the effect of immediate dentin sealing (IDS) with and without chlorhexidine (CHX) pretreatment on the shear bond strength (SBS) of dual-cure adhesive resin cement. Mid-coronal dentin surfaces were obtained from 75 human molars. They were randomly allocated into five groups in accordance to type of IDS [etch&rinse/ER (Adper Single Bond2) and universal/U adhesive systems (Single Bond Universal)] and presence of CHX application (n = 15): Group ER; Group ER + CHX; Group U; Group U + CHX; and Group C (no IDS). Dual-cure adhesive resin cements were bonded with a cylinder-shaped Teflon mold. The SBS was measured using a universal test machine. Fracture type was evaluated with stereomicroscope. The resin/dentin interfaces were examined with an environmental scanning electron microscope. Data were statistically analyzed with two-way analysis of variance and Bonferroni tests (p < .05). Regarding the IDS treatment groups with/without CHX, there were no significant differences in SBS (p > .05). Group U + CHX showed significantly higher SBS than Group C (p < .05). Regarding the presence of CHX, no significant differences in SBS were found (p > .05). The prevalent failure mode was the mixed type for most of the groups. Group C exhibited an intact and regular hybrid layer with no resin tag, whereas longer and clear resin-tag formation was visible for Group U + CHX. CHX pretreatment improved the bond strength between adhesive resin cement and dentin when IDS treatment was performed with a universal adhesive system.

The accuracy of the prediction models for surface roughness and micro hardness of denture teeth.

The paper aimed to compare the performance of artificial neural network (ANN) model with the results of in vitro experiments. For these experiments, maxillary molars of four different denture teeth were subjected to tea, coffee, cola, cherry juice, distilled water. Vickers microhardness and surface roughness values were measured. Subsequently, ANN model for the prediction of microhardness and surface roughness of different denture teeth were examined. A back-propagation ANN has been used to develop a model relating to the amount of microhardness and surface roughness. The independent variables of the model are distilled water, tea, filtered coffee, cola, cherry juice, time and denture teeth. Microhardness and surface roughness were chosen as the dependent variables. According to the results, a neural network architecture having one input layer with ten neurons, two hidden layers with six neurons, one output layer with two neurons and an epoch size of 48 gives better prediction. Prediction models for dental materials could also be supportive for in vitro studies.

Efficacy of denture cleaners on the surface roughness and Candida albicans adherence of sealant agent coupled denture base materials.

This study investigated the effect of denture cleansers on the surface roughness and Candida albicans adherence of surface sealant agent coupled denture base resins. One hundred and twenty specimens were fabricated from 2 polymethyl methacrylate (PMMA) (Meliodent; Acron MC) and 1 polyamide (Deflex) denture base materials, coated with a sealant agent (Palaseal) and divided into 4 groups (n=10) according to overnight cleaning procedures: distilled water (control), 5% sodium hypochlorite (NaOCl) and two different sodium perborate (Corega; Rapident). The surface roughness values were measured with a profilometer before (Ra0) and after 90 days immersion in denture cleaners (Ra1). Specimens were incubated with Candida albicans suspension and Candida colony- forming units (CFU) (Cfu/mm) were counted. Significant differences were found, between the Ra0 and Ra1 values of 5% NaOCl applied Acron MC, Deflex and also Rapident applied Deflex groups (p<0.05). Denture cleaning procedures had no significant effects on the quantitiy of Candida albicans.

The effect of home bleaching agents on the surface roughness of five different composite resins: A SEM evaluation.

The aim of this study was to investigate the effect of hydrogen peroxide (HP) and carbamide peroxide (CP) on the surface roughness of five different composite resins using profilometer and scanning electron microscope (SEM). Thirty-six specimens (1 mm thick, 10 mm in diameter) of five composite resins were fabricated. Each composite group was equally divided into three subgroups as control, CP and HP. In control group, specimens were stored in daily refreshed distilled water during the 14-day testing period. In other groups, 10% HP (Opalescence Treswhite) and 10% CP (Opalescence PF) were applied and surface roughness values (Ra) of each specimen were measured with a profilometer at the end of 14 days. Additionally, SEM analysis was performed to evaluate the surface deformations of composite resins. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Ra values of composite groups exposed to bleaching agents were statistically higher than control group (p < 0.05). There was no significant difference between Ra values after HP and CP application within each composite group while SEM micrographs showed higher surface alterations at HP group compared to CP. Among the composite resins tested, Ceram-X Mono revealed the lowest Ra values after CP and HP applications as seen at SEM images. Home bleaching agents increased the surface roughness of all composites. Except CP applied Ceram-X mono specimens, Ra values of all composite resins evaluated in this study exceeded the critical limit of 0.2 µm. Ceram-X mono was the least affected composite material after bleaching application. SCANNING 38:277-283, 2016. © 2016 Wiley Periodicals, Inc.

Effect of atmospheric plasma versus conventional surface treatments on the adhesion capability between self-adhesive resin cement and titanium surface.

PURPOSE: The aim of this study was to evaluate the effects of atmospheric plasma (APL) versus conventional surface treatments on the adhesion of self-adhesive resin cement to Ti-6Al-4V alloy. MATERIALS AND METHODS: Sixty plates of machined titanium (Ti) discs were divided into five groups (n=12): 1) Untreated (CNT); 2) Sandblasted (SAB); 3) Tribochemically treated (ROC); 4) Tungsten CarbideBur (TCB); 5) APL treated (APL). SEM analysis and surface roughness (Ra) measurements were performed. Self-adhesive resin cement was bonded to the Ti surfaces and shear bond strength (SBS) tests, Ra and failure mode examinations were carried out. Data were analyzed by one-way analysis of variance and chi-squared test. RESULTS: The lowest SBS value was obtained with CNT and was significantly different from all other groups except for APL. The ROC showed the highest SBS and Ra values of all the groups. CONCLUSION: It was concluded that the effect of APL on SBS and Ra was not sufficient and it may not be a potential for promoting adhesion to titanium.

Evaluation of staining susceptibility of resin artificial teeth and stain removal efficacy of denture cleansers.

OBJECTIVE: To assess the staining susceptibility of four acrylic resin (Ivostar, SR Vivodent PE, Major Dent, Integral) and a nanocomposite resin (Veracia) artificial teeth and to evaluate the stain removal efficacy of denture cleansers. MATERIALS AND METHODS: Sixty maxillary incisors of each brand (total = 300) were divided into three groups according to staining solution as coffee, red wine and tea. Baseline color measurements were performed with a spectrophotometer. Specimens were immersed in staining solutions for 14 h (2 h × 7 days) and then second color measurements were performed. Each group was further divided into four sub-groups according to denture cleanser as Corega tabs, Fittydent, NaOCl (0.5%) and distilled water (control) (n = 5). Specimens were immersed in denture cleansers for 8 h and third color measurements were made. Thus, the weekly simulation period was completed. This cycle was repeated 12 times to simulate a 3-month time period and measurements were performed at the end of the 4th, 8th and 12th cycles. ΔE values were calculated and data were analyzed with 3-way repeated measures ANOVA and Bonferroni tests. RESULTS: Significant color differences were found among the teeth and staining solutions, but all of the color differences were in the clinically acceptable range (ΔE < 5.5). Integral showed the highest ΔE values for all solutions, while Ivostar and Vivodent demonstrated the lowest ΔE values for red wine and tea solutions. There was no significant difference among the denture cleansers in terms of stain removal efficacy. CONCLUSIONS: Cross-linked acrylic (Integral) and nanocomposite (Veracia) resin teeth were more susceptible to staining. Denture cleansers were efficient on stain removal from artificial teeth.