Effect of Different Surface Treatments on Bond Strength of Resin Cement to a CAD/CAM Restorative Material.

PURPOSE: To investigate the effects of various surface treatment methods on the shear bond strength of self-adhesive resin cement to a novel CAD/CAM hybrid ceramic material. MATERIALS AND METHODS: A novel hybrid ceramic restorative material (Vita Enamic) was used in this study. Sixty resin block specimens were prepared and separated into six groups for each surface treatment method (n = 10); group 1: control group, no treatment applied; group 2: sandblasted by 30 µm silicate-coated alumina particles (CoJet Sandblasting); group 3: 50 µm Al2 O3 sandblasting; group 4: 10% hydrofluoric acid; group 5: no surface treatment + universal adhesive (3M Single Bond Universal); group 6: 200 mJ, 10 Hz 2W Er,Cr:YSGG laser treatment. For each specimen, surface roughness measurements in noncontact mode were taken after the surface treatments using a portable surface texture-measuring machine. A self-adhesive resin cement (3M U200) was applied on every surface treated with the help of a cylindrical mold (2 × 4 mm) and was filled gradually. Shear bond strength was measured using a universal test machine, and one-way ANOVA and a Duncan test (p = 0.05) were used to analyze the data. RESULTS: Mean values of the shear bond strength varied between 7.75 and 10.73 MPa. Bond strength values were enhanced by all surface treatment methods compared to the control group. The difference between group 5 and the control group (p < 0.05) was statistically significant, whereas there were no considerable differences between other treatment methods. CONCLUSION: Surface treatments of hybrid ceramic resin blocks could enhance the bond strength to resin cement; however, using Single Bond Universal without surface treatment showed a higher bond strength value.

Enhancing Dental Student Learning and Skill with Dental Bonding Utilizing a Shear Bond Strength Test.

Teaching dental students the proper protocol and application of bonding agents for improved composite restorations in the preclinical setting can be challenging due to difficulty in translating their bonding technique to clinical outcomes. The aim of this study was to examine the effectiveness of utilizing a shear bond strength test and to evaluate if it improved student performance and confidence in adhesive dentistry. All 106 third-year and 106 fourth-year dental students (total N=212) at the University of California, Los Angeles, School of Dentistry were invited to participate in a shear bond strength workshop in 2016. The hands-on workshop used a bond strength testing instrument to demonstrate the various principles and techniques of adhesive dentistry. A total of 54 third-year and 34 fourth-year students (total N=88) participated, for response rates of 51% and 32%, respectively. For the total students, there was a significant difference in the mean bond strength between the first and second attempts (p<0.001). For the third-year students, an increase in the mean shear bond strength was seen but was not significant (p=0.097). For the fourth-year students, there was a significant difference between the first and second attempts (p<0.001). A significant difference was also found in the aggregate self-ratings before and after the exercise (p<0.001). The students rated the exercise as an enjoyable way to learn about adhesive dentistry and agreed that it increased their confidence in performing bonding procedures. This exercise served as an innovative method of emphasizing proper technique with adhesive dentistry, while helping to build student confidence in the preclinical laboratory.

Shear bond strength and microleakage of a new self-etch adhesive pit and fissure sealant.

This study aimed to evaluate the shear bond strength (SBS) and microleakage of a new self-etch adhesive-based fissure sealant (EG) on aprismatic enamel in comparison to conventional fissure sealing with 30 s acid etching (CG). The fissures were sealed according to the manufacturer's instructions. Each group was divided into 3 subgroups: 1-day water storage, 3-month water storage, and 5,000× thermocycling. After measuring SBS using the Ultradent method, failure mode was analyzed. In additional 16 teeth, microleakage was tested using dye penetration method. Pairwise comparisons were analyzed using Mann-Whitney U-Test. Multiple linear regression was performed to assess the factors influencing on SBS. EG had significantly lower mean SBS (4.1 MPa±2.1) than the CG (17.6 MPa±6.4). CG (1.1%) performed significantly better than the EG (12.8%) in microleakage analysis. The tested EG yielded significantly inferior results and its clinical use should be decided after weighing its pros and cons.

Effect of Jig Design and Assessment of Stress Distribution in Testing Metal-Ceramic Adhesion.

PURPOSE: In testing adhesion using shear bond test, a combination of shear and tensile forces occur at the interface, resulting in complex stresses. The jig designs used for this kind of test show variations in published studies, complicating direct comparison between studies. This study evaluated the effect of different jig designs on metal-ceramic bond strength and assessed the stress distribution at the interface using finite element analysis (FEA). MATERIALS AND METHODS: Metal-ceramic (Metal: Ni-Cr, Wiron 99, Bego; Ceramic: Vita Omega 900, Vita) specimens (N = 36) (diameter: 4 mm, veneer thickness: 4 mm; base diameter: 5 mm, thickness: 1 mm) were fabricated and randomly divided into three groups (n = 12 per group) to be tested using one of the following jig designs: (a) chisel (CH) (ISO 11405), (b) steel strip (SS), (c) piston (PI). Metal-ceramic interfaces were loaded under shear until debonding in a universal testing machine (0.5 mm/min). Failure types were evaluated using scanning electron microscopy (SEM). FEA was used to study the stress distribution using different jigs. Metal-ceramic bond strength data (MPa) were analyzed using ANOVA and Tukey's tests (α = 0.05). RESULTS: The jig type significantly affected the bond results (p = 0.0001). PI type of jig presented the highest results (MPa) (p < 0.05) (58.2 ± 14.8), followed by CH (38.7 ± 7.6) and SS jig type (23.3 ± 4.2) (p < 0.05). Failure types were exclusively a combination of cohesive failure in the opaque ceramic and adhesive interface failure. FEA analysis indicated that the SS jig presented slightly more stress formation than with the CH jig. The PI jig presented small stress concentration with more homogeneous force distribution compared to the CH jig where the stress concentrated in the area where the force was applied. CONCLUSION: Metal-ceramic bond strength was affected by the jig design. Accordingly, the results of in vitro studies on metal-ceramic adhesion should be evaluated with caution. CLINICAL SIGNIFICANCE: When adhesion of ceramic materials to metals is evaluated in in vitro studies, it should be noted that the loading jig type affects the results. Clinical observations should report on the location and type of ceramic fractures in metal-ceramic reconstructions so that the most relevant test method can be identified.

Comparative study of bond strength to human and bovine dentine at three different depths / Estudo comparativo da resistência adesiva à dentina humana e bovina em três diferentes profundidades

The aim of this study was to compare the bond strength to three different depths of remaining human and bovine dentin, through shear bond strength test, and to establish a possible relationship among the depths of the substrates to contribute for the replacement of human dentin in bond strength tests. Forty-eight human teeth (H) and forty-eight bovine teeth (B), freshly extracted, stored in distilled water and frozen at -18 ° C for at most four weeks were used in this study. 240-, 400-, 600- and 800-grit sandpapers were used to expose the dentin and standardize the smear layer at 0.5, 1.0 and 2.0mm of dentin thickness. Scotchbond Multi-Purpose Plus adhesive system was used following the manufacturer’s instructions, on a standardized area of 4mm, followed by the incrementally application of Z100 resin composite (3M). The shear bond test was performed in the Instron Universal machine at cross-head speed of 0.5mm/min. Statistical analysis was performed by ANOVA (p <0.05). There were significant differences in bond strength between H and B teeth, with the highest values for H teeth. There was a significant difference in bond strength to the depths analyzed but there was similarity in behavior between H (0.5mm) and B (2mm) substrates. Bovine substrate can be used for laboratory studies of bond strength as indicative of the initial performance of new products, although the differences related to human substrate should be observed.

O objetivo do presente estudo foi comparar a resistência adesiva da dentina humana e bovina em três diferentes espessuras de remanescente, frente ao teste de cisalhamento, a fim de estabelecer uma possível relação de profundidade entre os substratos visando contribuir para a substituição da dentina humana em testes de adesão. Empregaram-se 48 dentes humanos (H) e 48 dentes bovinos (B), recém-extraídos, armazenados em água destilada e congelados a –18°C, por no máximo quatro semanas. Foram utilizadas lixas de granulação 240, 400, 600 e 800, para expor a dentina e padronizar a smear layer, com espessura de dentina de 0,5, 1,0 e 2,0mm. O sistema adesivo Scotchbond Multi-Uso Plus foi utilizado seguindo instruções do fabricante, em uma área padronizada de 4mm, seguido da aplicação incremental da resina Z100 (3M). O ensaio de cisalhamento foi realizado em máquina Instron Universal à velocidade de 0,5mm/min. Foi realizada análise estatística pelo teste ANOVA a dois critérios (p < 0,05). Houve diferença significativa entre a resistência adesiva em dentes H e B, sendo os maiores valores para H; houve diferença significativa de resistência para as profundidades analisadas; houve semelhança de comportamento entre os substratos H 0,5mm e B 2mm. O substrato B pode ser empregado em estudos laboratoriais de resistência adesiva como indicativos da performance inicial de novos produtos, observando-se as diferenças existentes entre eles.

The effect of cavity wall property on the shear bond strength test using iris method / 대한치과보존학회지

OBJECTIVES: In the unique metal iris method, the developing interfacial gap at the cavity floor resulting from the cavity wall property during polymerizing composite resin might affect the nominal shear bond strength values. The aim of this study is to evaluate that the iris method reduces the cohesive failure in the substrates and the cavity wall property effects on the shear bond strength tests using iris method. MATERIALS AND METHODS: The occlusal dentin of 64 extracted human molars were randomly divided into 4 groups to simulate two different levels of cavity wall property (metal and dentin iris) and two different materials (ONE-STEP(R) and ALL-BOND(R) 2) for each wall property. After positioning the iris on the dentin surface, composite resin was packed and light-cured. After 24 hours the shear bond strength was measured at a crosshead speed of 0.5 mm/min. Fracture analysis was performed using a microscope and SEM. The data was analyzed statistically by a two-way ANOVA and t-test. RESULTS: The shear bond strength with metal iris was significant higher than those with dentin iris (p = 0.034). Using ONE-STEP(R), the shear bond strength with metal iris was significant higher than those with dentin iris (p = 0.005), but not in ALL-BOND(R) 2 (p = 0.774). The incidence of cohesive failure was very lower than other shear bond strength tests that did not use iris method. CONCLUSIONS: The iris method may significantly reduce the cohesive failures in the substrates. According to the bonding agent systems, the shear bond strength was affected by the cavity wall property.