Effect of various surface treatments on relining bond strength of CAD-CAM denture base materials.

PURPOSE: The aim of this study was to analyze the impact of various surface treatments and production methods on the shear bond strength (SBS) between reline material and denture base resins. MATERIALS AND METHODS: One-hundred-twenty specimens were produced using conventional heat-polymerization, subtractive, and additive techniques. Each group consisted of 40 specimens. The specimens were divided into four subgroups, each with 10 samples, for surface treatments. These subgroups were: (1) Control-only monomer application, (2) 50 µm airborne-particle abrasion, (3) 110 µm airborne-particle abrasion, and (4) Roughening with tungsten carbide bur. Representative specimens from each subgroup were examined under SEM. Then, auto-polymerized resin was condensed in the center of the specimens. Specimens were subjected to thermal aging (5000 cycles at 5-55°C). The SBS test was conducted and failure loads were recorded. The data were evaluated by two-way ANOVA and Tukey pairwise multiple comparisons method (p < 0.05). RESULTS: The additively produced group showed significantly lower SBS than conventional and subtractive groups (p < 0.001), with no significant differences between the subtractive and conventional groups. Specimens that underwent monomer application only showed the lowest SBS among surface treatments, while 50 µm airborne-particle abrasion showed the highest SBS. Based on the partial eta-squared analysis results, the surface treatment mainly impacted SBS. CONCLUSIONS: Among the surface treatment methods, treating denture bases with 50 µm airborne-particle abrasion is more effective for maintaining adhesion, especially in the additive technique.

Effect of surface treatment and luting agent type on shear bond strength of titanium to ceramic materials.

PURPOSE: This study aimed to compare the effect of different surface treatments and luting agent types on the shear bond strength of two ceramics to commercially pure titanium (Cp Ti). MATERIALS AND METHODS: A total of 160 Cp Ti specimens were divided into 4 subgroups (n = 40) according to surface treatments received (control, 50 µm airborne-particle abrasion, 110 µm airborne-particle abrasion, and tribochemical coating). The cementation surfaces of titanium and all-ceramic specimens were treated with a universal primer. Two cubic all-ceramic discs (lithium disilicate ceramic (LDC) and zirconia-reinforced lithium silicate ceramic (ZLC)) were cemented to titanium using two types of resin-based luting agents: self-cure and dual-cure (n = 10). After cementation, all specimens were subjected to 5000 cycles of thermal aging. A shear bond strength (SBS) test was conducted, and the failure mode was determined using a scanning electron microscope. Data were analyzed using three-way ANOVA, and the Tukey-HSD test was used for post hoc comparisons (P < .05). RESULTS: Significant differences were found among the groups based on surface treatment, resin-based luting agent, and ceramic type (P < .05). Among the surface treatments, 50 µm air-abrasion showed the highest SBS, while the control group showed the lowest. SBS was higher for dual-cure resin-based luting agent than self-cure luting agent. ZLC showed better SBS values than LDC. CONCLUSION: The cementation of ZLC with dual-cure resin-based luting agent showed better bonding effectiveness to commercially pure titanium treated with 50 µm airborne-particle abrasion.

Effectiveness of different orthodontic adhesives and a universal bonding resin on the bond strength of brackets to different ceramics / Eficácia de diferentes adesivos ortodônticos e uma resina de ligação universal na resistência adesiva de bráquetes à diferentes cerâmicas

Objective: The aim of this study was to evaluate the effectiveness of different adhesives on the shear bond strength (SBS) of brackets bonded to different ceramic materials. Material and Methods: Fifty disk-shaped specimens were produced from lithium disilicate (IPS e.max CAD) and monolithic zirconia (Cercon) materials. Each specimen was polished with a three-step diamond polishing system. The polished ceramic surfaces were conditioned with universal bonding resin (Assure Plus) without pre-treatment, except for two specimens. Central brackets were bonded onto different ceramic specimens with different adhesives as follows: group 1: conventional adhesive onto the lithium disilicate; group 2: one-step adhesive onto the lithium disilicate; group 3: conventional adhesive onto the monolithic zirconia; group 4: one-step adhesive onto the monolithic zirconia. After thermal cycling, the specimens were subjected to the SBS test. The adhesive remnant index (ARI) scores were also recorded to evaluate bond failure type. Kruskal­Wallis and Mann-Whitney U tests were used for statistical analysis. Results: There were statistically significant differences among the SBS values (p˂0.05). The monolithic zirconia group with universal bonding resin and conventional orthodontic adhesive demonstrated the highest SBS value (6.34 MPa) and ARI scores. The lithium disilicate group showed the lowest SBS value (2.17 MPa) with the same protocol. No adhesive remained on the lithium disilicate specimens. Conclusion: One-step adhesive and universal bonding resin combination should not be considered as an alternative for lithium disilicate and monolithic zirconia restorations. Conventional adhesive and universal bonding resin application can be effective on non-pretreated ceramic surfaces during orthodontic bonding (AU)

Objetivo: o objetivo deste estudo foi avaliar a eficácia de diferentes adesivos na resistência ao cisalhamento (SBS) de bráquetes colados a diferentes materiais cerâmicos. Material e métodos: Cinquenta espécimes em forma de disco foram produzidos a partir de materiais de dissilicato de lítio (IPS e.max CAD) e zircônia monolítica (Cercon). Cada amostra foi polida com um sistema de polimento de diamante de três passos. As superfícies cerâmicas polidas foram condicionadas com resina de ligação universal (Assure Plus) sem pré-tratamento, exceto para dois corpos-de-prova. Bráquetes centrais foram colados em diferentes corpos de prova cerâmicos com diferentes adesivos da seguinte forma: grupo 1: adesivo convencional sobre dissilicato de lítio; grupo 2: adesivo de uma etapa sobre o dissilicato de lítio; grupo 3: adesivo convencional sobre zircônia monolítica; grupo 4: adesivo de uma etapa sobre a zircônia monolítica. Após a ciclagem térmica, os corpos-de-prova foram submetidos ao teste SBS. Os escores do índice de remanescente adesivo (ARI) também foram registrados para avaliar o tipo de falha de adesão. Os testes U de Kruskal-Wallis e Mann-Whitney foram usados para análise estatística. Resultados: Houve diferenças estatisticamente significativas entre os valores de SBS (p˂0,05). O grupo de zircônia monolítica com resina de colagem universal e adesivo ortodôntico convencional demonstrou o maior valor de SBS (6,34 MPa) e escores de ARI. O grupo de dissilicato de lítio apresentou o menor valor de SBS (2,17 MPa) com o mesmo protocolo. Nenhum adesivo permaneceu nas amostras de dissilicato de lítio. Conclusão: A combinação de adesivo de uma etapa e resina de ligação universal não deve ser considerada como uma alternativa para restaurações de dissilicato de lítio e zircônia monolítica. A aplicação de adesivo convencional e resina de colagem universal podem ser eficazes em superfícies de cerâmica não pré-tratadas durante a colagem ortodôntica (AU)

Shear bond strength of a self-adhesive resin cement to dentin surface treated with Nd:YAG and femtosecond lasers.

This study aims to evaluate the effect of Nd:YAG and femtosecond lasers irradiation on the shear bond strength (SBS) of a self-adhesive resin cement to the human dentin surface. One hundred extracted third molar teeth were randomly divided into 10 experimental groups according to dentin surface treatments; with and without the bonding agent, Nd:YAG 302 J/cm2 and 440 J/cm2, femtosecond 4 J/cm2 and 7 J/cm2, and control groups were prepared. After surface treatments, a self-adhesive resin cement was luted by using a bonding jig (Ultradent Products Inc.). The specimens were then subjected to shear test at a crosshead speed of 0.5 mm/min, and failure loads were recorded as megapascal (MPa). Two-way analysis of variance and Tukey HSD tests were performed (p Ë‚ 0.05). Representative specimens from each experimental subgroup were examined by means of SEM. The highest SBS values were obtained in Group 302 J/cm2 Nd:YAG with bonding agent, and there is no statistical difference between Group 440 J/cm2 Nd:YAG with bonding and Group 7 J/cm2 femtosecond with bonding (p > 0.05). The lowest SBS values were observed in Group control without bonding agent. Nd:YAG and femtosecond laser treatments improved the adhesion between the dentin surface and the self-adhesive resin cement.

Effect of a Home Bleaching Agent on the Ion Elution of Different Esthetic Materials.

PURPOSE: To investigate the effect of a 16% carbamide peroxide home bleaching agent on the ion elution of different esthetic restorative materials and to determine if the released ions exceed the minimal risk levels. MATERIALS AND METHODS: Ceramic materials comprising a low-fusing porcelain (Vita VM7), lithium disilicate glass-ceramics (IPS e.max Press and IPS e.max CAD), zirconium substructure materials (IPS e.max ZirCAD and Vita In-Ceram YZ for InLab), and ceromers (Estenia and Tescera ATL) were chosen. Thirty disk-shaped specimens (2 mm thickness and 10 mm diameter) were fabricated from each material and then were divided into 3 experimental groups to receive one of the following solutions: acetic acid (positive control), a bleaching agent and distilled water (negative control) (n = 10/group). For the bleaching agent, the specimens were subjected to a 16% carbamide peroxide solution (VOCO Perfect Bleach) for 2 hours per day for 14 days. A 4% acetic acid solution was applied at 80°C for 16 hours according to the ISO 6872:2015 protocol and specimens of negative control group were immersed in distilled water for 16 hours. Ion elution measurements were conducted with inductively coupled plasma atomic emission spectroscopy (ICP-AES) after immersion in the solutions, and the weight loss of the materials was measured with a precision scale. Changes in the surface topography were investigated by a scanning electron microscopy (SEM).The results were evaluated using multivariate analysis of variance (MANOVA). RESULTS: Among the specimens tested, the most ion elution was observed in the Tescera ATL group, and the least ion elution was observed in the e.max ZirCAD group in all solutions. Ion elution was found to be greater in the bleaching agent than in the acetic acid and distilled water groups. Sodium was the most released ion, and zinc and lithium were the least released among the elements tested. CONCLUSIONS: It should be noted that the bleaching-related ion release may exceed toxic doses even if restorative materials meet ISO 6872 standards, and the materials should be protected before home bleaching to prevent ion elution.

Color Stability of CAD/CAM Fabricated Inlays after Accelerated Artificial Aging.

PURPOSE: To investigate the influence of accelerated artificial aging on the color stability of three different inlay restorations produced with a CAD/CAM system. MATERIALS AND METHODS: Thirty non-carious human mandibular molar teeth were used. The teeth were embedded in autopolymerizing acrylic resin blocks. Standard Class I inlay cavities were prepared, and the teeth were randomly divided into three groups (n = 10) to fabricate inlay restorations: (1) a feldspathic-ceramic group, (2) a resin nano-ceramic group, and (3) a leucite glass-ceramic group. Optical impressions were made with CEREC software, and the restorations were designed and then milled. The inlays were adhesively cemented with a dual-polymerizing resin cement and left in distilled water at room temperature for 1 week. Color measurements were performed with a spectrophotometer before and after accelerated aging in a weathering machine with a total energy of 150 kJ/m(2) . Changes in color (∆E, ∆L, ∆a, ∆b, ∆C) were determined using the CIE L*a*b* system. The results were assessed using a one-way ANOVA and Tukey's HSD test (p = 0.05). RESULTS: The color changes of the materials ranged from 2.1 to 9.29. The highest color change was seen in the resin nano-ceramic material. This change was not clinically acceptable (∆E > 5.5). No significant differences were found in the ∆L and ∆a values of the test groups. CONCLUSIONS: Color changes were observed in each evaluated material after accelerated aging. All CAD/CAM inlays became darker in appearance, more saturated, a little reddish, and more yellow.

In vitro study of fracture strength of provisional crown materials.

PURPOSE: The purpose of this report was to evaluate the effect of the fabrication method and material type on the fracture strength of provisional crowns. MATERIALS AND METHODS: A master model with one crown (maxillary left second premolar) was manufactured from Cr-Co alloy. The master model was scanned, and the data set was transferred to a CAD/CAM unit (Yenamak D50, Yenadent Ltd, Istanbul, Turkey) for the Cercon Base group. For the other groups, temporary crowns were produced by direct fabrication methods (Imident, Temdent, Structur Premium, Takilon, Systemp c&b II, and Acrytemp). The specimens were subjected to water storage at 37℃ for 24 hours, and then they were thermocycled (TC, 5000×, 5-55℃) (n=10). The maximum force at fracture (Fmax) was measured in a universal test machine at 1 mm/min. Data was analyzed by non-parametric statistics (α=.05). RESULTS: Fmax values varied between 711.09-1392.1 N. In the PMMA groups, Takilon showed the lowest values (711.09 N), and Cercon Base showed the highest values (959.59 N). In the composite groups, Structur Premium showed the highest values (1392.1 N), and Acrytemp showed the lowest values (910.05 N). The composite groups showed significantly higher values than the PMMA groups (P=.01). CONCLUSION: Composite-based materials showed significantly higher fracture strengths than PMMA-based materials. The CAD-CAM technique offers more advantages than the direct technique.