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OBJECTIVE: Strength is one of the preferred parameters used in dentistry for determining clinical indication of dental restoratives. However, small dimensions of CAD/CAM blocks limit reliable measurements with standardized uniaxial bending tests. The objective of this study was to introduce the ball-on-three-ball (B3B) biaxial strength test for dental for small CAD/CAM block in the context of the size effect on strength predicted by the Weibull theory. METHODS: Eight representative chairside CAD/CAM materials ranging from polycrystalline zirconia (e.max ZirCAD, Ivoclar-Vivadent), reinforced glasses (Vitablocs Mark II, VITA; Empress CAD, Ivoclar-Vivadent) and glass-ceramics (e.max CAD, Ivoclar-Vivadent; Suprinity, VITA; Celtra Duo, Dentsply) to hybrid materials (Enamic, VITA; Lava Ultimate, 3M ESPE) have been selected. Specimens were prepared with highly polished surfaces in rectangular plate (12×12×1.2mm3) or round disc (Ø=12mm, thickness=1.2mm) geometries. Specimens were tested using the B3B assembly and the biaxial strength was determined using calculations derived from finite element analyses of the respective stress fields. Size effects on strength were determined based on results from 4-point-bending specimens. RESULTS: A good agreement was found between the biaxial strength results for the different geometries (plates vs. discs) using the B3B test. Strength values ranged from 110.9MPa (Vitablocs Mark II) to 1303.21MPa (e.max ZirCAD). The strength dependency on specimen size was demonstrated through the calculated effective volume/surface. SIGNIFICANCE: The B3B test has shown to be a reliable and simple method for determining the biaxial strength restorative materials supplied as small CAD/CAM blocks. A flexible solution was made available for the B3B test in the rectangular plate geometry.

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Introduction and objective: GuttaFlow2 is a further development of the silicone sealer GuttaFlow, exhibiting a stiffer consistency. This is intended to overcome possible problems regarding retention of the apical part of the root canal filling when preparing for a fiber post. GuttaFlow2 is delivered within a capsule, like GuttaFlow, or within an automix syringe. This study compared apical dye leakage of GuttaFlow2 in comparison to GuttaFlow and AH Plus. The null hypothesis tested was that different sealers exhibited similar microleakage. Material and methods: Seventy extracted human lower premolars with fully mature apices were root canal prepared to 45/.04 and divided into seven groups: group 1: AH Plus sealer, group 2: "normal" setting GuttaFlow, group 3: "fast" setting GuttaFlow, group 4: GuttaFlow2 within a capsule, group 5: GuttaFlow2 within an automix syringe, group 6: positive control, group 7: negative control (n = 10 each). Root canals were filled with sealer (except group 7) and a master gutta-percha cone size 40/.04 using the non-compaction technique. A dye penetration test was carried out by centrifugation for 3 min at 30 G within 5 % methylene blue dye. Linear dye penetration was recorded. Statistical evaluation was carried out with IBM SPSS 19.0 (α = 0.05). Results: The positive control was significantly different from all other groups (ANOVA, p < 0.001; Student-Newman-Keuls post-hoc test p < 0.05). When the control groups were disregarded, no significant differences were apparent. Groups 1 to 5 showed low leakage values when compared with results of earlier studies using a similar methodology. Conclusion: All sealers tested exhibited low dye leakage values.

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OBJECTIVES: To investigate the adhesive potential of novel zirconia primers and universal adhesives to surface-treated zirconia substrates. METHODS: Zirconia bars were manufactured (3.0mm×3.0mm×9.0mm) and treated as follows: no treatment (C); air abrasion with 35µm alumina particles (S); air abrasion with 30µm silica particles using one of two systems (Rocatec or SilJet) and; glazing (G). Groups C and S were subsequentially treated with one of the following primers or adhesives: ZP (Z-Prime Plus), AZ (AZ Primer); MP (Monobond Plus); SU (ScotchBond Universal) and; EA (an Experimental Adhesive). Groups Rocatec and SilJet were silanized prior to cementation. Samples form group G were further etched and silanized. Bars were cemented (Multilink) onto bars of a silicate-based ceramic (3.0mm×3.0mm×9.0mm) at 90° angle, thermocycled (2.500 cycles, 5-55°C, 30s dwell time), and tested in tensile strength test. Failure analysis was performed on fractured specimens to measure the bonding area and crack origin. RESULTS: Specimens from group C did not survive thermocycling, while CMP, CSU and CEA groups survived thermocycling but rendered low values of bond strength. All primers presented a better bond performance after air abrasion with Al2O3 particles. SilJet was similar to Rocatec, both presenting the best bond strength results, along with SMP, SSU and CEA. G promoted intermediate bond strength values. Failure mode was predominately adhesive on zirconia surface combined to cohesive of the luting agent. CONCLUSIONS: Universal adhesives (MP, SU, EA) may be a considerable alternative for bonding to zirconia, but air abrasion is still previously required. Air abrasion with silica particles followed by silane application also presented high bond strength values.

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Objective: This study evaluated sealing properties of root canal fillings with an additional composite barrier. The null hypothesis tested was that different sealers and different methods of sealer removal did not influence microleakage. Material and methods: Eighty extracted human molars with fully mature apices had root canal prepared to size 60 taper .02 and divided into eight groups: three experimental groups for each sealer and negative/positive control (n = 10 each). Teeth of experimental groups were mounted into the molar region of a training puppet to simulate clinical conditions. Root canals were filled with AH Plus or GuttaFlow and gutta-percha. Excess sealer was removed with: ethanol-moistened foam pellet only, additional preparation with a water-cooled diamond bur or additional etch-and-rinse procedure (37% phosphoric acid gel). All procedures were carried out until clean as judged by the naked eye. In all groups except the positive control Syntac was applied to the access cavity. Tetric flow was applied in two increments of 1 mm each. A dye penetration test was carried out by centrifugation for 3 min at 30 G within 5% methylene blue dye. Statistical evaluation was carried out with PASW 18.0 (α = 0.05). Results: Although the two sealers had different chemical composition, sealer exhibited no influence on the results, whereas technique of sealer removal did (Two-way-ANOVA, p < 0.001). Groups with "foam pellet" or "bur preparation" showed significantly more leakage than groups with "etch-and rinse" (SNK, p < 0.05). Conclusion: Applying an etch-and-rinse procedure prior to Syntac may be beneficial for the adhesive seal over root canal fillings.

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OBJECTIVES: To evaluate the toothbrush wear resistance of infiltrated artificial white spot lesions following two infiltration strategies, and to assess their ultramorphology. METHODS: Flat enamel surfaces from freshly extracted bovine teeth were polished and immersed in a Buskes demineralising solution for 30 days to create incipient caries-like lesions (white spots). Two experimental regions on the surface of each tooth were infiltrated with an infiltrant and a commercial etch-and-rinse adhesive. Toothbrush abrasion was applied for 20,000 cycles. Vertical wear loss of the infiltrated areas was measured after 10,000 and 20,000 cycles against unabraded and abraded enamel using confocal laser scanning microscopy (CLSM; multiple t-tests, α=0.05). Each lesion's surface and cross-section were evaluated under CLSM and scanning electron microscopy after etching and infiltration to assess ultramorphology. RESULTS: After 20,000 abrasion cycles, a statistically non-significant difference in vertical wear loss was measured for the infiltrant versus the adhesive compared with the original enamel (42.6±20.7 µm vs. 40.4±18.5 µm, p>0.05). Irregular surface profiles were common for the adhesive-infiltrated group as a result of peeling and blistering of the resin-covering layer. Ultramorphology of the infiltrated lesions revealed different patterns of penetration regarding density and depth. CONCLUSIONS: Although both infiltration strategies had equivalent wear resistance to toothbrush abrasion, surface and morphological aspects pointed to improved surface stability and infiltration quality for the infiltrant material.

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Introduction: The purpose of this study was to test different sealerremoval protocols following root canal filling before adhesive seal ofaccess cavities. Material and methods: Forty single root teeth wereselected for the study, prepared to size 60 taper .02, and filled withAH plus and a single gutta-percha cone size 55 taper .02. Excesssealer was removed with: ethanol-moisturised foam pellet (group 1),pellet and additional etch-and-rinse procedure (group 2), pellet andadditional preparation with a water-cooled diamond bur (group 3) orby etch-and-rinse following temporary filling for one week (group 4).Syntac and Tetric flow were used as a secondary protective seal. Adye penetration test (centrifugation 3min / 30G; 5% methylene blue)was carried out. Results were analyzed statistically using PASW 18.0(Kolmogorov-Smirnov-test, Kruskal-Wallis-test, Mann-Whitney-test;p < 0.05). Results: Groups 2, 3 and 4 revealed less leakage than group 1(p < 0.05; Mann-Whitney-tests) and displayed no coloration exceedingthe adhesive seal. Teeth with immediate (group 2) or delayed (group4) adhesive seal showed similar results. Conclusion: Acid etching orbur preparation may be recommended before adhesively sealing theaccess cavity in single-rooted teeth. There is no need to wait until thesealer has set.

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OBJECTIVES: The aim of this study was to evaluate the fatigue limits of the dentin-composite interfaces established either with an etch-and-rinse or an one-step self-etch adhesive systems under tensile and bending configurations. METHODS: Flat specimens (1.2 mm×5 mm×35 mm) were prepared using a plexiglass mold where dentin sections from human third molars were bonded to a resin composite, exhibiting the interface centrally located. Syntac Classic and G-Bond were used as adhesives and applied according to the manufacturer's instructions. The fluorochrome Rhodamine B was added to the adhesives to allow for fractographic evaluation. Tensile strength was measured in an universal testing machine and the bending strength (n=15) in a Flex machine (Flex, University of Antwerp, Belgium), respectively. Tensile (TFL) and bending fatigue limits (BFL) (n=25) were determined under wet conditions for 10(4) cycles following a staircase approach. Interface morphology and fracture mechanisms were observed using light, confocal laser scanning and scanning electron microscopy. Statistical analysis was performed using three-way ANOVA (mod LSD test, p<0.05). RESULTS: Tensile and bending characteristic strengths at 63.2% failure probability for Syntac were 23.8 MPa and 71.5 MPa, and 24.7 MPa and 72.3 MPa for G-Bond, respectively. Regarding the applied methods, no significant differences were detected between adhesives. However, fatigue limits for G-Bond (TFL=5.9 MPa; BFL=36.2 MPa) were significantly reduced when compared to Syntac (TFL=12.6 MPa; BFL=49.7 MPa). Fracture modes of Syntac were generally of adhesive nature, between the adhesive resin and dentin, while G-Bond showed fracture planes involving the adhesive-dentin interface and the adhesive resin. SIGNIFICANCE: Cyclic loading under tensile and bending configurations led to a significant strength degradation, with a more pronounced fatigue limit decrease for G-Bond. The greater decrease in fracture strength was observed in the tensile configuration.

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OBJECTIVES: To evaluate the depth of wear gaps of new self-adhesive cements after toothbrush abrasion and ACTA wear test. METHODS: Luting spaces (325+/-25 microm width, 2mm depth) were produced in Empress 2 ceramic blocks with a diamond saw to obtain flat substrate segments for toothbrush abrasion (n=24) and ACTA wear (n=27). After etching and silanization, the slits were filled with 8 self-adhesive cements, 2 conventional resin cements and 1 flowable composite, stored for 2 weeks in distilled water at 37 degrees C and planished to the cement level. Toothbrush abrasion was carried out in a toothbrush simulator (Willytec, Germany) for 20,000 cycles (load 1N) using an abrasive slurry based on a commercial toothpaste (Elmex, Gaba, Germany, RDA=77). The ACTA wear experiment was performed following the ACTA protocol in millet seed slurry for 400,000 cycles (Willytec). The gap replicas were measured for vertical wear loss under a confocal laser scanning microscope (CLSM). The data were analyzed using one-way ANOVA and a mod-LSD test at p<0.05. RESULTS: Toothbrush wear values were lower than the ones obtained for the ACTA wear test for all cements. In the toothbrush test Bifix SE, Clearfil SA, SmartCem 2, G-Cem and Maxcem Elite obtained the highest values together with Grandio Flow. Grandio Flow and AllCem showed to be the most resistant to the ACTA wear test, while SpeedCem the least resistant. No correlation was found between the two wear test experiments. CONCLUSION: Self-adhesive cements have good wear resistance to toothbrush abrasion but most of them wear more rapidly under higher loads in the ACTA test than conventional resin cements and flowable composites.

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Introdução e objetivo:: Os sistemas adesivos autocondicionantes têm sido largamente utilizados por dentistas e pesquisadores nos procedimentos adesivos de restaurações dentárias. O objetivo deste estudo foi avaliar a resistência de união ao microcisalhamento de sistemas adesivos autocondicionantes em dentina profunda. Material e métodos: Prepararam-se 50 terceiros molares humanos até obtenção de superfícies planas de dentina profunda (2 mm abaixo do limite amelodentinário do sulco central), abrasionadas com lixa de carbeto de silício n.º 600. As amostras foram aleatoriamente divididas em cinco grupos (n = 10), de acordo com os grupos experimentais: 1) adesivo convencional Syntac (controle), 2) adesivo autocondicionante One-Up Bond F Plus (um passo), 3) Hybrid Bond (um passo), 4) AdheSE (dois passos) – unidos ao compósito Tetric Ceram – e 5) Silorane System Adhesive (dois passos), unido ao compósito de baixa contração FiltekSilorane. Os materiais foram aplicados segundo orientações dos fabricantes e com uma matriz Tygon. Os corpos-de-prova foram armazenados em água destilada a 37±2ºC por uma semana. Determinou-se a resistência de união por meio da máquina universal de ensaios Zwick, a uma velocidade de 0,5 mm/minuto. Resultados: Os resultados obtidos em MPa (DP) foram analisados estatisticamente (Anova e teste de Tukey – p < 0,05) e apresentaram os seguintes dados: 2) 25,5 (4,4); 1) 24,9 (5,3); 3) 22,4 (8,1); 4) 21,5 (4,4) e 5) 18,1 (7,2). O teste de Tukey mostrou variações significativas entre os grupos 2 e 5, que não evidenciaram diferenças com os demais grupos testados. Conclusão: O adesivo Silorane e o compósito Filtek Silorane tiveram resistência de união similar à dos demais materiais, porém menor que o One-Up Bond F Plus, quando este foi utilizado com o Tetric Ceram. Os resultados sugerem que, em termos de resistência de união, os adesivos autocondicionantes podem ser uma boa alternativa nos procedimentos restauradores adesivos em dentina profunda.

Introduction and objecttiivee:: The self-etching adhesive systems have been widely used by dentists and researchers in the procedures of adhesive dental restorations. The purpose of this study was to evaluate the microshear bond strength of self-etching adhesive systems to deep dentin.Material and methods: Fifty freshly extracted human third molars were prepared using a diamond saw until obtaining flat surfaces of deep dentin (2 mm below the DEJ of central sulcus), wet-abraded with 600-grit SiC paper. The samples were randomly divided into five groups (n = 10) according to the experimental groups: 1) conventional adhesive Syntac (control), 2) one-step self-etching adhesive One-Up Bond F Plus, 3) onestep self-etching adhesive Hybrid Bond, 4) two-step self-etching adhesive AdheSE – bonded to Tetric Ceram resin composite; and the 5) two-step self-etching adhesive Silorane System Adhesive bonded to low shrinkage resin composite Filtek Silorane. The adhesives and the resin composite were applied according to the manufacturers’ instructions, and using a Tygon tubing mold. The samples were stored in distilled water at 37±2ºC for one week. Microshear bond strengths were determined using a Zwick universal testing machine at a crosshead speed of 0.5 mm/minute. Results: The results obtained in MPa (SD) were statistically analyzed (Anova and Tukey test, p < 0.05), and showed the following results: 2) 25,5 (4,4); 1) 24,9 (5,3); 3) 22,4 (8,1); 4) 21,5 (4,4) and 5) 18,1 (7,2). There was statistically significant variation between groups 2 and 5; which did not show difference to the other groups tested. Conclusion: The Silorane System Adhesive and the low shrinkage resin composite Filtek Silorane showed similar bond strength to Syntac, Hybrid Bond and AdheSE – bonded to Tetric Ceram resin composite; however, being lower than One-Up Bond F Plus bonded to Tetric Ceram. Regarding the bond strength, the results suggest that self-etching adhesive systems can...