The objective of this study was to evaluate the tensile (sigma(t)) and shear bond strength (sigma(s)) of a glass-infiltrated alumina-based zirconia-reinforced ceramic (IZ--Vita In-Ceram Zirconia) to a composite resin, testing the hypothesis that silica coating (SC--Cojet, 3M-Espe) produces higher bond strength values than other ceramic surface treatments. Specimens were fabricated and tested according to the manufacturers' instructions, and to ISO6872 and ISO11405 specifications. Sixty IZ disk specimens were polished through 1 microm and divided into 3 groups (n = 20) according to the following surface treatments: HF - 9.5% hydrofluoric acid (Ultradent) for 1 min; SB--sandblasting with 25-microm aluminum oxide particles for 10 s; SC--silica coating for 10 s. Silane (3M-Espe), adhesive (Single Bond, 3M-Espe) and a composite resin cylinder (Z100, 3M-Espe) were applied and polymerized to the treated bonding area (3.5 mm in diameter). Ten specimens from each group (n = 10) were tested for sigma(t) and ten specimens were tested for sigma(s), using a universal testing machine (EMIC DL 2000) at a crosshead speed of 1 mm/min. The data were statistically analyzed by ANOVA and Tukey tests (alpha = 0.05). The mean and standard deviation values (MPa) and statistical groupings for sigma(t) were: HF - 3.5 +/- 1.0a; SB - 7.6 +/-1.2b; and SC - 10.4+/-1.8c. For sigma(s), the values were: HF - 10.4 +/- 3.1A; SB - 13.9+/- 3.1B; and SC - 21.6 +/- 1.7C (p < 0.05). The groups presented the same statistical ranking of mean values for both test methods. The SC-treated IZ ceramic presented a significant increase in mean bond strength values for both test methods, confirming the study hypothesis.
This study evaluated the flexural strength (sf) and the diametral tensile strength (st) of light-cured composite resins, testing the hypothesis that there is a positive relation between these properties. Twenty specimens were fabricated for each material (Filtek Z250- 3M-Espe; AM- Amelogen, Ultradent; VE- Vit-l-escence, Ultradent; EX- Esthet-X, Dentsply/Caulk), following ISO 4049 and ANSI/ADA 27 specifications and the manufacturers instructions. For the st test, cylindrical shaped (4 mm x 6 mm) specimens (n = 10) were placed with their long axes perpendicular to the applied compressive load at a crosshead speed of 1.0 mm/min. The sf was measured using the 3-point bending test, in which bar shaped specimens (n = 10) were tested at a crosshead speed of 0.5 mm/min. Both tests were performed in a universal testing machine (EMIC 2000) recording the fracture load (N). Strength values (MPa) were calculated and statistically analyzed by ANOVA and Tukey (a = 0.05). The mean and standard deviation values (MPa) were Z250-45.06 +/- 5.7; AM-35.61 +/- 5.4; VE-34.45 +/- 7.8; and EX-42.87 +/- 6.6 for st; and Z250-126.52 +/- 3.3; AM-87.75 +/- 3.8; VE-104.66 +/- 4.4; and EX-119.48 +/- 2.1 for sf. EX and Z250 showed higher st and sf values than the other materials evaluated (p < 0.05), which followed a decreasing trend of mean values. The results confirmed the study hypothesis, showing a positive relation between the material properties examined.
The objective of this study was to evaluate the flexural strength (sigma f) and hardness (H) of direct and indirect composites, testing the hypotheses that direct resin composites produce higher sigma f and H values than indirect composites and that these properties are positively related. Ten bar-shaped specimens (25 mm x 2 mm x 2 mm) were fabricated for each direct [D250 - Filtek Z250 (3M-Espe) and D350 - Filtek Z350 (3M-Espe)] and indirect [ISin - Sinfony (3M-Espe) and IVM - VitaVM LC (Vita Zahnfabrik)] materials, according to the manufacturer's instructions and ISO4049 specifications. The sigma f was tested in three-point bending using a universal testing machine (EMIC DL 2000) at a crosshead speed of 0.5 mm/min (ISO4049). Knoop hardness (H) was measured on the specimens' fragments resultant from the sigma f test and calculated as H = 14.2P/l(2), where P is the applied load (0.1 kg; dwell time = 15 s) and l is the longest diagonal of the diamond shaped indent (ASTM E384). The data were statistically analyzed using Anova and Tukey tests (alpha = 0.05). The mean sigma f and standard deviation values (MPa) and statistical grouping were: D250 - 135.4 +/- 17.6a; D350 - 123.7 +/- 11.1b; ISin - 98.4 +/- 6.4c; IVM - 73.1 +/- 4.9 d. The mean H and standard deviation values (kg/mm(2)) and statistical grouping were: D250 - 98.12 +/- 1.8a; D350 - 86.5 +/- 1.9b; ISin - 28.3 +/- 0.9 c; IVM - 30.8 +/- 1.0 c. The direct composite systems examined produce higher mean sigma f and H values than the indirect composites, and the mean values of these properties were positively correlated (r = 0.91), confirming the study hypotheses.
UHOHDVHGGIURPPGLIIHUHQWWUHVWRUDWLYHHPDWHULDOVVVWRUHGGLQQDUWL¿FLDOOVDOLYDDDQGGGRXEOHGLVWLOOHG water. Material and Methods: Cylindrical specimens (10 x 1 mm) were prepared from 4 GLIIHUHQWWUHVWRUDWLYHHPDWHULDOVV.DYLWDQQ3OXV9LWUHPHU'\UDFWW([WUDDQGG6XUH¿O)RUUHDFKK PDWHULDOVSHFLPHQVVZHUHHSUHSDUHGRIIZKLFKKZHUHHVWRUHGGLQQP//DUWL¿FLDOOVDOLYDDDQGG RIIZKLFKKZHUHHVWRUHGGLQQP//RIIGRXEOHGLVWLOOHGGZDWHU&RQFHQWUDWLRQVVRIIÀXRULGHHDQGG aluminum in the solutions were measured using ion chromatography. Measurements were taken daily for one week and then weekly for two additional weeks. Data were analyzed using two-way ANOVA and Duncan's multiple range tests (p<0.05). Results: The highest DPRXQWVVRIIERWKKÀXRULGHHDQGGDOXPLQXPPZHUHHUHOHDVHGGE\\WKHHUHVLQPRGL¿HGGJODVVVLRQRPHUU FHPHQWW 9LWUHPHUU LQQ GRXEOHGLVWLOOHGG ZDWHUU S $OOO PDWHULDOVV UHOHDVHGG VLJQL¿FDQWO\\ PRUHHÀXRULGHHLQQGRXEOHGLVWLOOHGGZDWHUUWKDQQLQQDUWL¿FLDOOVDOLYDDS,QQDUWL¿FLDOOVDOLYD none of the materials were observed to release aluminum. Conclusion: It was concluded WKDWWVWRUDJHHPHGLDDDQGGPHWKRGGRIIDQDO\VLVVVKRXOGGEHHWDNHQQLQWRRDFFRXQWWZKHQQWKHHÀXRULGHH and aluminum release from dental materials is assessed.
This study showed that the symptom's questionnaire for gastroesophageal reflux disease has "face validity", excellent reproducibility, easy comprehension and was quickly answered by patients. The correlation with Johnson-DeMeester's score was null.
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