Effect of composite surface treatment and aging on the bond strength between a core build-up composite and a luting agent

Objective: The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Material and Methods: Eighty blocks (8x8x4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5 degrees C and 55 degrees C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mu m Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (mu TBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5 degrees C and 55 degrees C, with a dwell time of 30 s in each bath) and mu TBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (alpha=0.05). Results: The mu TBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Conclusion: Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement.

Effect of ceramic etching protocols on resin bond strength to a feldspar ceramic

This study sought to evaluate the resin micro-tensile bond strength (MTBS) stability of a leucite-reinforced ceramic after different ceramic etching protocols. The microtensile test had 40 ceramic blocks (5x5x6 mm) assigned to five groups (n=8), in accordance with the following surface etching protocols: NE nonetched (control); 9HF: hydrofluoric (HF) acid etching (9% HF)+wash/dry; 4HF: 4%HF+wash/dry; 5HF: 5%HF+wash/dry; and 5HF+N: 5%HF+neutralizer+wash/dry+ultrasonic-cleaning. Etched ceramic surfaces were treated with a silane agent. Next, resin cement blocks were built on the prepared ceramic surface and stored for 24 hours in distilled water at 37 degrees C. The specimens were then sectioned to obtain microtensile beams (32/block), which were randomly assigned to the following conditions, nonaged (immediate test) and aged (water storage for 150 days plus 12,000 thermal cycles), before the microtensile test. Bond strength data were submitted to one-way analysis of variance and Tukey test (alpha=0.05). Additional ceramic samples were subjected to the different ceramic etching protocols and evaluated using a scanning electron microscope (n=2) and atomic force microscopy (n=2). Aging led to a statistically significant decrease in the MTBS for all groups, except the untreated one (NE). Among the groups submitted to the same aging conditions, the untreated (NE) revealed inferior MTBS values compared to the 9HF and 4HF groups. The 5HF and 5HF+N groups had intermediate mean values, being statistically similar to the higher values presented by the 9HF and 4HF groups and to the lower value associated with the NE group. The neutralization procedure did not enhance the ceramic/resin cement bond strength. HF acid etching is a crucial step in resin/ceramic bonding.

Comparison of Different Dentin Pretreatment Protocols on the Bond Strength of Glass Fiber Post Using Self-etching Adhesive

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

In vitro effect of calcium-containing prescription-strength fluoride toothpastes on bovine enamel erosion under hyposalivation-simulating conditions

Purpose: To evaluate the ability of calcium-containing prescription-strength fluoride (F) toothpastes in preventing enamel erosion under low salivary flow simulating conditions. Methods: Enamel and dentin bovine specimens were assigned to the following groups: A - placebo; B - 1,100 ppm F/NaF (Aquafresh Advanced); C - 5,000 ppm F/NaF (Prevident 5000 Booster); D - 5000 ppm F/NaF+calcium sodium phosphosilicate (Topex Renew); and E - 5,000 ppm F/NaF+tri-calcium phosphate (Clinpro 5000). Specimens were positioned in custom-made devices, creating a sealed chamber on the surface, connected to peristaltic pumps. Citric acid was injected into the chamber for 2 minutes, followed by artificial saliva (0.05 ml/minute), for 60 minutes, 4x/day, for 3 days. Aquafresh was also tested under normal salivary flow (0.5 ml/minute), as reference (Group F). Specimens were exposed to the toothpastes for 2 minutes, 2x/day. After cycling, surface loss (SL) and concentration of loosely- and firmly-bound F were determined. Data were analyzed by ANOVA. Results: Group A (placebo) presented highest surface loss (SL), while Group F had the lowest, for both substrates. For enamel, none of the dentifrices differed from Group B or among each other. For dentin, none of the dentifrices differed from Group B, but Group E showed greater protection than Group C. Group E presented the highest F concentrations for both substrates, only matched by Group D for firmly-bound fluoride on enamel. All fluoridated dentifrices tested reduced SL, with no additional benefit from higher F concentrations. Some formulations, especially Clinpro 5000, increased F availability on the dental substrates, but no further erosion protection was observed.

Linear and undulating periodized strength plus aerobic training promote similar benefits and lead to improvement of insulin resistance on obese adolescents

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of Insertion Techniques for Resin Cement and Mechanical Cycling on the Bond Strength Between Fiber Posts and Root Dentin

Purpose: To evaluate the effect of the insertion technique for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin.Materials and Methods: Sixty-four single-rooted bovine teeth were endodontically prepared to receive glass-fiber posts. The insertion of cement into the root canal was performed using one of the following techniques: POS, insertion with the post; LEN, the use of a lentulo-type drill; EXP, insertion with a straight-tip explorer; or CEN, the use of a Centrix syringe. Half of the specimens were mechanically cycled. All specimens were sectioned into slices of 1.8 mm for the push-out test and 0.5 mm for analysis of the cement layer quality.Results: The insertion technique affected the interaction between factors (bond strength and mechanical cycling; p < 0.0001). Insertion of the Centrix syringe after mechanical cycling showed the highest bond values (13.6 +/- 3.2 MPa). Group-to-group comparisons for baseline and cycled conditions indicated that mechanical cycling significantly influenced the bond strength (p < 0.0001) of the POS and CEN groups. The quality of the cement layer did not differ between the techniques when evaluated in the middle (p = 0.0612) and cervical (p = 0.1119) regions, but did differ in the apical region (p = 0.0097), where the CEN group had better layer quality for the two conditions tested (baseline and cycled).Conclusion: The use of the Centrix syringe improved the homogeneity of the cement layer, reducing the defects in the layer and increasing adhesive strength values to dentin, even after mechanical cycling.

Effects of high and low volume of strength training on muscle strength, muscle volume and lipid profile in postmenopausal women

Changes in lipid profile are considered a risk factor for cardiovascular disease (CVD), especially in postmenopausal woman who have been associated with age-related loss of muscle mass. The beneficial role of aerobic exercise in the prevention of CVD has been well documented. However, the effect of strength training has not been established. The purpose of this study was to determine the changes of lipoprotein levels after 12 weeks of different volumes of strength training and its correlation with strength and muscle volume in postmenopausal women. The participants were randomized into three groups: low volume (LVST; n = 12, 1 set) and high volume of strength training (HVST; n = 11, 3 sets), or control group (n = 12). Training groups performed 12 weeks of supervised strength exercises, 15 maximum repetitions, five times a week, 20 minutes for LVST and 40 minutes for HVST for each training session. Measurements included body composition, strength and muscle volume, as well as blood analysis (glucose, total cholesterol, triglycerides, low-density lipoprotein, and high-density lipoprotein) pre- and post-training. The HVST and LVST improved the one-repetition maximum knee extension strength (p < 0.001), maximal dynamic strength (p < 0.001), and muscle volume (p = 0.048). Post-training triglyceride was lower in HVST when compared to LVST and the control group (p = 0.047). Even though they present the same neuromuscular and morphological adaptations in postmenopausal women, the HVST is more effective than LVST in improving the lipid profile of postmenopausal woman, and can be considered as an ideal program of intervention to reverse changes in lipid metabolism commonly found in this group. Copyright (C) 2014, The Society of Chinese Scholars on Exercise Physiology and Fitness. Published by Elsevier (Singapore) Pte Ltd. All rights reserved.

Influence of thicknesses of smear layer on the transdentinal cytotoxicity and bond strength of a resin-modified glass-ionomer cement

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of storage times on bond strength of resin cements to root canal

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Study of thermocycling effect on the bond strength between an aluminous ceramic and a resin cement

This study evaluated the effect of thermocycling on the bond strength between Procera AllCeram (Nobel-Biocare) and a resin cement (Panavia F, Kuraray CO). Nine ceramic blocks with dimensions of 5x6x6mm were conditioned at one face with Rocatec System (Espe). After, they were luted with Panavia F to composite resin blocks (Clearfil AP-X, Kuraray CO). The nine groups formed by ceramic, cement and composite resin were split up obtaining 75 samples with dimensions of 12x1x1mm and adhesive surface presenting 1mm2±0.1mm2 of area. The samples were divided into 3 groups (n=25): G1 - 14 days in distilled water at 37ºC; G2 – 6,000 cycles in water (5ºC - 55ºC – 30s); G3 – 12,000 cycles in water (5ºC - 55ºC – 30s). The samples were tested in a universal testing machine (EMIC) at a crosshead speed of 1mm/min. Data were analyzed by ANOVA and Tukey tests. The results indicated that mean values of rupture tension (MPa) of G1 (10.71 ± 3.54) did not differ statistically (p <5%) from G2 (9.01 ± 3.90), however there was statistical difference between G1 and G3 (7.28 ± 3.00). It was concluded that thermocycling significantly reduced the bond strength values when samples were submitted to 12,000 cycles.

Influence of Nd:YAG or Er:YAG laser surface treatment on microtensile bond strength of indirect resin composites to resin cement. Lasers surface treatment of indirect resin composites

This study evaluated the influence of the surface pretreatment of indirect resin composite (Signum, Admira Lab and Sinfony) on the microtensile bond strength of a resin cement. Sixty samples made of each brand were divided into 6 groups, according to surface treatment: (1) control; (2) controlled-air abrasion with Al2O3; (3) Er:YAG Laser 200 mJ, 10 Hz, for 10s; (4) Er: YAG Laser 300 mJ, 10 Hz, for 10 s; (5) Nd:YAG 80 mJ, S15Hz for 1 min; (6) Nd:YAG 120mJ, 15 Hz for 1 min. After treatments, all the groups received an application of 37% phosphoric acid and adhesive. The pair of blocks of the same brand were cemented to each other with dual resin cement. The blocks were sectioned to obtain resin-resin sticks (1 x1 mm) and analyzed by microtensile bond testing. The bond strength values were statistically different, irrespective of the surface treatment performed, with highest values for Sinfony (43.81 MPa) and lowest values for Signum (32.33 MPA). The groups treated with the Nd:YAG laser showed the lowest bond strength values and power did not interfere in the results, both for Nd:YAG laser and Er:YAG. Controlled-air abrasion with Al203 is an efficient surface treatment method and the use of the Nd:YAG and Er:YAG lasers reduced bond strength, irrespective of the intensity of energy used.

The effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root thirds

The purpose of this study was to evaluate the effect of self-adhesive and self-etching resin cements on the bond strength of nonmetallic posts in different root regions. Sixty single-rooted human teeth were decoronated, endodontically treated, post-space prepared, and divided into six groups. Glass-fiber (GF) posts (Exacto, Angelus) and fiber-reinforced composite (FRC) posts (EverStick, StickTeck) were cemented with self-adhesive resin cement (Breeze) (SA) (Pentral Clinical) and self-etching resin cement (Panavia-F) (SE) (Kuraray). Six 1-mm-thick rods were obtained from the cervical (C), middle (M), and apical (A) regions of the roots. The specimens were then subjected to microtensile testing in a special machine (BISCO; Schaumburg, IL, USA) at a crosshead speed of 0.5 mm/min. Microtensile bond strength data were analyzed with two-way ANOVA and Tukey's tests. Means (and SD) of the MPa were: GF/SA/C: 14.32 (2.84), GF/SA/M: 10.69 (2.72), GF/SA/A: 6.77 (2.17), GF/SE/C: 11.56 (4.13), GF/SE/M: 6.49 (2.54), GF/SE/A: 3.60 (1.29), FRC/SA/C: 16.89 (2.66), FRC/SA/M: 13.18 (2.19), FRC/SA/A: 8.45 (1.77), FRC/SE/C: 13.69 (3.26), FRC/SE/M: 9.58 (2.23), FRC/SE/A: 5.62 (2.12). The difference among the regions was statistically significant for all groups (p < 0.05). The self-adhesive resin cement showed better results than the self-etching resin cement when compared to each post (p < 0.05). No statistically significant differences in bond strengths of the resin cements when comparable to each post (p > 0.05). The bond strength values were significantly affected by the resin cement and the highest values were found for self-adhesive resin cement.

Combined training (aerobic plus strength) potentiates a reduction in body fat but demonstrates no difference on the lipid profile in postmenopausal women when compared to aerobic training with a similar training load

The aim of this study was to verify the effects of aerobic and combined training on the body composition and lipid profile of obese postmenopausal women and to analyze which of these models is more effective after equalizing the training load. Sixty five postmenopausal women (age=61.0±6.3 years) were divided into three groups: Aerobic Training (AT,n= 15), Combined Training (CT,[strength+aerobic],n=32) and control group (CG,n=18). Their body composition: upper body fat (TF), fat mass (FM), percentage of fat mass and fat free mass (FFM) were estimated by DXA. The lipid profile, total cholesterol, HDL-cholesterol and LDL-cholesterol were assessed. There was a statistically significant difference in the TF (AT= -4.4 %, CT= -4.4%, and CG= 1.0%, p= 0.001) and FFM (AT= 1.7%, CT= 2.6%, and CG= -1.4%, p= 0.0001) between the experimental and the control groups. Regarding the percentage of body fat, there was a statistically significant difference only between the CT and CG groups (AT= -2.8%, CT= -3.9% and CG= 0.31%, p= 0.004). When training loads were equalized, the aerobic and combined training decreased core fat and increased fat-free mass, but only the combined training potentiated a reduction in percentage of body fat in obese postmenopausal women after the training program. HDL-c levels increased in the combined group and the chol/HDL ratio (atherogenic index) decreased in the aerobic group, however, there were no significant differences between the intervention programs. Taken together, both the exercise training programs were effective for improving body composition and inducing an anti-atherogenic status.

Influence of Nd:YAG laser on intrapulpal temperature and bond strength of human dentin under simulated pulpal pressure

The aim of this study was to evaluate the effects of simulated pulpal pressure (SPP) on the variation of intrapulpal temperature (ΔT) and microtensile bond strength (μTBS) to dentin submitted to an adhesive technique using laser irradiation. One hundred sound human molars were randomly divided into two groups (n = 50), according to the presence or absence of SPP (15 cm H2O). Each group was divided into five subgroups (n = 10) according to Nd:YAG laser energy (60, 80, 100, 120, 140 mJ/pulse). The samples were sequentially treated with the following: 37 % phosphoric acid, adhesive (Scotchbond Universal), irradiation with Nd:YAG laser (60 s), and light curing (10 s). ΔT was evaluated during laser irradiation using a type K thermocouple. Next, a composite resin block was build up onto the irradiated area. After 48 h, samples were submitted to microtensile test (10 kgf load cell, 0.5 mm/min). Data were analyzed by two-way ANOVA and Tukey tests (p = 0.05). ANOVA revealed significant differences for ΔT and TBS in the presence of SPP. For ΔT, the highest mean (14.3 ± 3.23 °C)(A) was observed in 140 mJ and without SPP. For μTBS, the highest mean (33.4 ± 4.15 MPa)(A) was observed in 140 mJ and without SPP. SPP significantly reduced both ΔT and μTBS during adhesive procedures, lower laser energy parameters resulted in smaller ΔT, and the laser parameters did not influence the μTBS values.

Effect of peroxide bleaching on the biaxial flexural strength and modulus of bovine dentin

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)