Avaliação de dois métodos de registro da relação central em desdentados totais

Objective: to compare, in the horizontal plane, the mandibular positions determined by two methods for registering the centric relation(CR): inclination of the head backward (IHB) and unstrained hinging movement (UHM), in edentulous patients. The mull hypothesis was that there is not difference between the two methods. Material and Methods: Twenty edentulous subjects were selecred for this study (n = 20). All patients were manipulated to CR position using the methods IHB and UHM. The CR measure of each method was registered in one extraoral devide, which was fixed as the maxillary and mandibular record bases. For each patient, the two CR positions were registered in the same extraoral devide. To measure the anteroposterior and lateral linear variations between the points registered for each technique, it was used a profile projector (Model 6C, Nikon/USA). The data (um) were statiscally analyzed using the Tukey test (p,0.05) and Pearson correlation test. Results: The difference between CR position obtained by the methods in anteroposterior position differed statically from zero (p = 0.001) and that there was no significant difference (p = 0.479) when compared the Cr positions with the medium line: UHM (0,56+_0,35um) and IHB (0,65+0.52um). It wasn´t observed Pearson linear correlation between the anteroposterior and lateral linear measures of the methods (r = 0.26; p = 0.268.0.05). Conclusion: It can be conclude that the method UHM presented a higher mandibular retrusion that the method IHBObjetivo: Comparar, no plano horizontal, as posições mandibulares determinadas por dois métodos de registro para determinação da posição de relação central (RC): inclinação da cabeça para trás (IC) os métodos guiado não forçado (GNF), em pacientes edêntulos. A hipótese nula é de que não haverá diferença entre os dois métodos. Material e Método: 20 pacientes desdentados totais foram selecionados para este estudo (n=20). Todos pacientes foram manipulados para posição de RC utilizando os métodos IC e GNF. A mensuração da posição de RC determinada por cada método foi registrada em um dispositivo extra-oral, cujas componentes foram fixados nos planos de orientação maxilar e mandibular. Para cada paciente, as duas posições de RC foram registradas no mesmo dispositivo extra-oral. Para mensurar as variações ântero-posteriores e laterais entre os pontos registrados por cada técnica, foi utilizado um projetor de perfil (Modelo 6C, Nikon/USA). Os dados (mm) foram analisados estatisticamente utilizando o teste T (pResultados: A diferença entre a posição de RC obtida pelos métodos na posição ântero-posterior diferiu estatisticamente de zero (p=0.001) e que não houve diferença significante (p=0,479) quando comparada as posições de RC em relação à linha média: UHM (0,56±0,35mm) e IHB (0,65±0,52mm). Não foi observada correlação linear de Pearson entre as medidas lineares antero-posteriores e laterais dos métodos estudados (r=0,26; p=0,2680,05). Conclusão: Pode-se concluir que método GNF gerou uma retrusão mandibular maior que o método IC

Effect of different surface treatments and multimode adhesive application on the Weibull characteristics, wettability, surface topography and adhesion to CAD/CAM lithium disilicate ceramic

This paper aims to evaluate the effect of different surface treatments on surface topography, wettability, and shear bond strength of resin cement to glass ceramic. Methodology: For SBS test, 32 blocks (7x7x2 mm) of lithium disilicate were obtained and randomly divided into eight groups (four blocks per group) according to each surface treatment (HF 20 s, 60 s, 120 s + silanization/S or Scotch Bond Universal/ SBU) and the Monobond Etch & Prime - MEP application followed or not by SBU. On each treated surface ceramic block, up to four dual-curing resin cement cylinders were prepared and light-cured for 40s (N=120/n=15). The specimens were thermocycled (10,000 cycles, 5-55°C, 30 s) and the SBS test (50KgF, 0.5 mm/min) was performed. Furthermore, failure analysis, wettability, AFM, and SEM were carried out. SBS data (MPa) were analyzed using Student's t-test, two-way ANOVA, Tukey's test (5%) and Weibull's analysis. Results: For HF experimental groups, two-way ANOVA presented the factors “etching time” and “bonding agent” as significant (p<0.05). After silane application, the HF groups presented similar bond strength. SBU application compromised the SBS, except for 120s etching time (HF120sS: 23.39ᵃ±6.48 MPa; HF120sSBU: 18.76ᵃ±8.81MPa). For MEP groups, SBU application did not significantly affect the results (p=0.41). The MEP group presented the highest Weibull modulus (4.08A) and they were statistically different exclusively from the HF20sSBU (0.58B). Conclusion: The HF 20s, 60s, 120 s followed by silane, promoted similar resin-bond strength to ceramic and the SBU application after HF or MEP did not increase the SBS

Long-term fracture load of all-ceramic crowns : effects of veneering ceramic thickness, application techniques, and cooling protocol

To evaluate, in vitro, the effects of the cooling protocol, application technique, and veneering ceramic thickness on the fracture resistance of ceramic crowns with Y-TZP frameworks. 80 frameworks were made from zirconia by the CAD/CAM technique and divided into 8 groups (n = 10) according to the factors: ?application technique? (stratified-L and pressed -P), ?thickness? (1 mm and 2 mm), and ?cooling protocol? (slow-S and fast-F) of the feldspathic veneering ceramic. After, all crowns were cemented over G10 preparations with resin cement (Panavia F, Kuraray), mechanically cycled (2x106 cycles, 200 N, 3Hz), and subjected to the axial compression resistance test (0.5 mm/min, 10 kN). The data (N) underwent descriptive statistical analysis by 3-way ANOVA and Tukey?s test (5%). Fracture analysis was performed to determine the possible origin of failure. The factors ?cooling protocol? (P=0.0058) and ?application? technique (P=0.0001) influenced the fracture resistance of the crowns. For pressed veneer technique, the P2S (4608.9±464.5). A presented significantly higher results than that P2F(3621.1±523.0)BCD (Tukey?s test). For the stratified technique, this difference was not observed (P>0.05). The thickness of the veneering ceramic was not significant regardless of the cooling protocol and technique (P>0.05). The predominant failure mode was chipping of the ceramic veneer originating in the subsurface. The pressed technique, used with a slow-cooling protocol, leads to the best outcome for the veneering of all-ceramic crowns

Effect of temporary cement removal methods from human dentin on zirconia-dentin adhesion

This study evaluated the effect of temporary cement residue removal methods from human coronary dentin on the bond strength of adhesively-luted zirconia on dentin. Forty non-carious human molars were embedded in acrylic resin and the dentin surfaces were exposed. Temporary acrylic crowns were provisionally cemented with zinc oxide cement without eugenol and stored in distilled water (37 °C/15 days). After crown removal, the excess temporary cement was removed from dentin according to one of the following cleaning methods: (n = 8 per group): (a) air-water rinse (AW), (b) pumice paste (PP), (c) air-abrasion with aluminum oxide particles (Al2O3) (AA), (d) sodium bicarbonate spray (SB) or (e) glycine powder (CP). Forty zirconia cylinders were made and each cylinder was adhesively luted onto each tooth after adhesive resin (Scotch Bond Universal, 3 M ESPE-SBU) application using resin cement (RelyX Ultimate, 3 M ESPE) and photo-polymerized from each surface for 20 s. The bonded specimens were stored in distilled water (37 °C) for 90 days. The bonded interface was loaded under shear (1 mm/min). Data (MPa) were analyzed using 1-way ANOVA and Tukey's test (α = 0.05). Mean bond strength was significantly affected by the cleaning method (p = 0.0289). Cleaning with AA method resulted in significantly higher bond strength than with SB (p  0.05). All cleaning methods were effective in removing temporary resin cement from dentin surfaces. Air-abrasion with aluminum oxide particles was more effective than with sodium bicarbonate spray promoting adhesion between zirconia and dentin

Effect of glazing application side and mechanical cycling on the biaxial flexural strength and Weibull characteristics of a Y-TZP ceramic

Glaze application on monolithic zirconia (Y-TZP) can be a practical approach to improve the mechanical properties of this material. Objective: Our study evaluated the effect of glazing side and mechanical cycling on the biaxial flexure strength (BFS) of a Y-TZP. Methodology: Eighty sintered Y-TZP discs (Ø:12 mm; thickness: 1.2 mm - ISO 6872) were produced and randomly assigned into eight groups (n=10), according to the factors “glazing side” (control – no glazing; GT – glaze on tensile side; GC – glaze on compression side; GTC – glaze on both sides) and “mechanical aging” (non-aged and aged, A – mechanical cycling: 1.2×106, 84 N, 3 Hz, under water at 37°C). Specimens were subjected to BFS test (1 mm/min; 1,000 Kgf load cell) and fractured surfaces were analyzed by stereomicroscopy and SEM. Hsueh’s rigorous solutions were used to estimate the stress at failure of glazed specimens. Two-way ANOVA, Tukey’s test (5%), and Weibull analysis were performed. Results: The “glazing side”, “mechanical aging” and the interaction of the factors were significant (p<0.05). Groups GC (1157.9±146.9 MPa), GT (1156.1±195.3 MPa), GTC (986.0±187.4 MPa) and GTC-A (1131.9±128.9 MPa) presented higher BFS than control groups (Tukey, 5%). Hsueh’s rigorous solutions showed that the maximum tensile stress was presented in the bottom of zirconia layer, at the zirconia/glaze interface. Weibull characteristic strength (σo) of the GC was higher than all groups (p<0.05), except to GT, GTC-A and GTC, which were similar among them. The fractography showed initiation of failures from zirconia the tensile side regardless of the side of glaze application and fatigue. Conclusion: Glazing zirconia applied on both tensile and compression sides improves the flexural strength of Y-TZP, regardless the mechanical aging

Influência de diferentes protocolos de jateamento na resistência à flexão e na estabilidade estrutural de uma cerâmica policristalina de zircônia tetragonal parcialmente estabilizada com ítria

Este estudo avaliou o efeito de diferentes protocolos de jateamento na resistência à flexão biaxial e na estabilidade estrutural de uma cerâmica de Y-TZP. Para tanto, duzentos e dezesseis discos sinterizados de Y-TZP (Lava, 3M ESPE) (ISO 6872, diâmetro: 15 mm, espessura: 2 mm) foram confeccionados pelo fabricante. Para o ensaio de resistência à flexão, 180 discos (n=10) foram divididos entre 18 grupos de acordo com os fatores “tipo de partícula (Al2O3- 50 e 110μm; SiO2- 30 e 110 μm)”, “pressão (2,5 e 3,5 bar)” e “ciclagem mecânica (CM) (com e sem)”. O jateamento foi realizado a uma distância de 10 mm e com duração de 20 s: Gr1- Controle – (sem tratamento de superfície); Gr2- Al2O3 50 μm/2,5 bar; Gr3- Al2O3 50 μm/3,5 bar; Gr4- Al2O3 110 μm/2,5 bar; Gr5- Al2O3 110 μm/3,5 bar; Gr6- SiO2 30 μm/2,5 bar; Gr7- SiO2 30 μm/3,5 bar; Gr8- SiO2 110 μm/2,5 bar; Gr9- SiO2 110 μm /3,5 bar. Os grupos Gr10 a Gr18 são respectivamente os grupos anteriores submetidos à CM (100.000 ciclos, 50 N, 4 Hz, água 370C. Em seguida todas as amostras foram submetidas ao ensaio de resistência à flexão biaxial (ISO 6872) em máquina de ensaio universal (EMIC, 1 mm/min). Após ensaio de flexão, os dados obtidos (MPa) foram submetidos ao teste de Dunnett (5%) e à Análise de Variância (3 fatores). Para determinar a quantidade e profundidade de possíveis transformações de fase da zircônia (t→m) induzida pelo jateamento e/ou pela ciclagem mecânica, foi realizada a análise de difração de Raios-X em vinte amostras (n=2) dos grupos Gr1 ao Gr9 e Gr18, antes e após tratamento térmico (ciclo de queima da VM9/Vita). Os resultados demonstraram que todos os protocolos de jateamento promoveram um aumento significativo da resistência à flexão da cerâmica de Y-TZP em relação...This study evaluated the effect of different air-particle-abrasion protocols on the biaxial flexural strength and on the structural stability of Y-TZP ceramic. Disc shaped (ISO 6872, Ø: 15 mm, thick: 2 mm) sintered zirconia specimens (N=216) were obtained from the manufacturer (Lava, 3M ESPE). To the flexure test 180 discs (n=10) were divided among the groups according to the factors “particle (Al2O3 50 and 110μm; SiO2 30 and 110 μm)”, “pressure (2.5 and 3.5 bar)” and “mechanical cycling (MC)(with and without)”. The air-particle-abrasion protocols were performed with 10 mm of distance and duration of 20 s: Gr1- Control – (without air-particle-abrasion); Gr2- Al2O3 50 μm/2,5 bar; Gr3- Al2O3 50 μm/3,5 bar; Gr4- Al2O3 110 μm/2,5 bar; Gr5- Al2O3 110 μm/3,5 bar; Gr6- SiO2 30 μm/2,5 bar; Gr7- SiO2 30 μm/3,5 bar; Gr8- SiO2 110 μm/2,5 bar; Gr9- SiO2 110 μm /3,5 bar. The groups Gr10 to Gr18 are those groups before submitted to MC, respectively (100.000 cycles; 50 N, 4 Hz, water 370C). After, all specimens were tested for biaxial flexural strength (ISO 6872) in a universal testing machine (EMIC). After, all specimens were tested for biaxial flexural strength (ISO 6872) in a universal testing machine (EMIC). The data were submitted to statistical tests ANOVA and Dunnett (5%). To determine the percentage and deep of possible zirconia transformations (te mo) after the air-particle-abrasion protocols and/or MC, the X-Ray diffraction was performed on 20 samples (n=2) from the groups Gr1 to Gr9 and Gr18, before and after thermal treatment (VM9/Vita firing cycle). The results showed that all air-particle-abrasion protocols increased significantly the flexure strength of the Y-TZP ceramic compared to the negative Control... (Complete abstract click electronic access below)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Avaliação das discrepâncias marginal vertical e interna de coroas totais cerâmicas confeccionadas por um sistema CAD/CAM, variando o término cervical

Este estudo avaliou a discrepância marginal (DM) e interna (DI) de coroas totais cerâmicas fabricadas pelo sistema CAD/CAM Cerec inLab, frente a três diferentes términos cervicais. A hipótese nula foi que o tipo de término não influencia a DM e DI das coroas. A partir de três troquéis metálicos com distintos términos cervicais, foram fresadas trinta coroas cerâmicas (ProCad/Ivoclar Vivadent) (n=10): CI) chanfro inclinado; CL) chanfro largo e O) ombro arredondado. Para análise da DM, mensurou-se, em 50 pontos, a distância entre a margem externa de cada coroa à margem do término cervical do respectivo troquel metálico. Utilizando a técnica da réplica, avaliou-se a DI de cada coroa em 12 pontos igualmente distribuídos por regiões: término (T), axial (A) e oclusal (Ocl). As mensurações foram realizadas em microscópio óptico (250x). Os dados obtidos ('mü'm) foram submetidos aos testes estatísticos ANOVA e de Tukey (5%). Os resultados demonstraram que grupo O (28,24'mais ou menos'11,42'mü'm) gerou valores de DM significativamente inferiores (p=0,001) aos dos grupos CI (99,92'mais ou menos'18,32'mü'm) e CL (64,71'mais ou menos'25,64'mü'm), os quais diferiram estatisticamente entre si. A análise da DI demonstrou que o grupo CL (183,01'mais ou menos'62,82'müm) apresentou valores inferiores (p=0,0014) aos demais grupos: CI (216,26'mais ou menos'83,23 'mü'm) e O (219,12'mais ou menos'87,24'mü'm), os quais foram semelhantes entre si. Observou-se também que a DI variou entre as regiões mensuradas (p=0,0001). A hipótese nula foi rejeitada. Baseado nos resultados pôde-se concluir que, apesar das diferenças estatísticas observadas entre os grupos, os três términos cervicais geraram coroas com valores de DM e DI aceitáveis clinicamente.This study evaluated the marginal discrepancy (MD) and internal (ID) of ceramic crowns manufactured by the CAD/CAM system Cerec inLab, varying the finish line. The null hypothesis was that the preparations won't influence the MD and ID of the crowns. From three metallic dies with different finish lines, thirty ceramic crowns (ProCad/Ivoclar Vivadent) were machined (n=10): TC) tilted chamfer; LC) large chamfer and RS) rounded shoulder. For MD analysis, were measured, in 50 points, the distance between each crown extern edge to the edge of the cervical preparation on the respective metallic die. Using the replica technique, it was evaluated the ID of each crown at 12 points equally distributed between the regions: end (E), axial (A) and oclusal (Ocl). The mensurations were done in optical microscope (250x). The data obtained ('mü'm) were submitted to the statistical tests ANOVA and Tukey (5 %). The results demonstrated that the group RS (28,24 'mais ou menos'11,42'mü'm) produced MD values smaller (p=0,001) than the groups TC (99,92'mais ou menos'18,32'mü'm) and LC (64,71'mais ou menos'25,64 'mu'm), which, between them, differed statistically. The analysis of ID demonstrated that the group LC (183,01'mais ou menos'62,82 'mü'm) presented values lower (p=0,0014) than TC (216,26'mais ou menos'83,23'mü'm) and RS (219,12'mais ou menos'87,24 'mü'm), which were similar between them. It was also noticed that ID varied between the measured regions (p=0.0001). The null hypothesis was rejected. It was concluded that, in spite of the statistical differences observed between the groups, the three cervical finish lines produced crowns with MD and ID values clinically acceptance.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES