The Effects of Er,Cr:YSGG laser on shear bond strength of orthodontic lingual brackets to CAD/CAM ceramic systems.

Purpose: The aim of this study is to compare the bond strength of lingual brackets bonded to resin-matrix and lithium disilicate based-ceramic crowns following various surface treatments. Materials and methods: Sixty ceramic crowns (IPS Emax and Cerasmart) were fabricated by CAD/CAM. Er,Cr:YSGG laser, sandblasting with aluminium oxide and hydrofluoric acid treatment effects on ceramics was tested (n=10/group). A light-cure orthodontic adhesive was used to bond lingual brackets to the ceramic surfaces. Bond strengths of the brackets to ceramics were assessed by shear bond test. The remnant adhesive on bracket and ceramic surfaces was inspected with a light microscope and adhesive remnant index scores were recorded. The data were analyzed statistically using the Kruskal-Wallis test followed by the Mann-Whitney U-test. Results: Cerasmart ceramic specimens showed lower shear bond strength values than IPS Emax ceramic specimens (p<0.05). The statistical analysis of the surface treatment groups regarding bond strength were ranked as follows: Laser ≤ Hydrofluoric acid ≤ Sandblasting (p=0.058). While laser-treated Cerasmart ceramic group displayed the lowest SBS (9.39 MPa), hydrofluoric acid-treated IPS Emax group had the highest (16.8 MPa) bond strength value. Conclusion: The use of Er,Cr:YSGG lasers for etching of CAD-CAM ceramics could be a promising alternative to "conventional techniques", to improve bond strength of lingual brackets to IPS Emax and Cerasmart ceramics.

Effects of the substructure thickness, the resin cement color and the finishing procedure on the color and translucency of zirconia-based ceramic restorations.

BACKGROUND: The ability to simulate the natural appearance of teeth in dental restorations is one of the most important factors that make treatment successful. OBJECTIVES: The present study evaluated the effects of the substructure thickness, the resin cement color and the finishing procedure on the color and translucency of bilayer zirconia-based ceramic restorations. MATERIAL AND METHODS: Yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) CAD/CAM blocks (dimensions of 6.0 × 5.5 × 0.4 mm, 6.0 × 5.5 × 0.8 mm, and 6.0 × 5.5 × 1.6 mm) veneered with the fluorapatite-containing ceramics were used. For polishing, the surfaces of half of the test specimens were adjusted with a blue-belted diamond porcelain bur and a white polishing rubber, and the other half were glazed. The test specimens were then cemented with 2 different colors of the same self-adhesive resin cement to the resin composite. A spectrophotometer was used to measure the L*, a*, and b* color attributes of the specimens. Additionally, the ΔE values were calculated to determine color differences between each group and the control. Data was analyzed using the multifactorial repeated-measures analysis of variance (ANOVA) and subgroup analysis (p < 0.005). RESULTS: It was found that the highest substructure thickness resulted in the lowest color change (ΔE = 1.24) (p < 0.005). However, a substructure thickness of 0.8 mm showed less color change (ΔE = 1.39) than the 0.4-mm thickness (ΔE = 3.85) in the translucent resin cement/polished subgroup, as measured against a gray background (p = 0.001). CONCLUSIONS: The most significant factor in masking the abutment color in zirconia-based restorations is the thickness of the substructure. The surface finishing procedure or the resin cement color do not have a primary effect on the color change or translucency.

Bond strength of various post-core restorations with different lengths and diameters following cycle loading.

PURPOSE: This in vitro study aims to evaluate the bonding strengths of Polyether ether ketone (PEEK), Polyether ketone (PEKK), Fiber, and Zirconia (ZrO2) post-core restorations with posts in different diameter and length following chewing simulator. MATERIALS AND METHODS: Endodontic treatment was performed on 256 intact maxillary central teeth. The test specimens were prepared in four groups according to the types of materials: Glass fiber post-composite core (FB-n:64), Zirconia post-core (Zr-n:64), PEEK post-core (PE-n:64), and PEKK post-core (PK-n:64). The groups were divided into four subgroups according to diameter and length (n:16): Group 1: 10 mm length 1.75 mm diameter, Group 2: 10 mm length 1.5 mm diameter, Group 3: 7 mm length 1.75 mm diameter, Group 4: 7 mm length 1.5 mm diameter. Custom PEKK, PEEK, Zirconia post-cores, and Zirconia crowns were milled on the CAD/CAM. The post-cores and crowns were cemented to the teeth with dual-cure resin cement. After that, all subgroups were divided into control and cyclic loading groups. During the cycling, the control test group was kept in distilled water at 37±1oC before the push-out test. Half of the specimens were loaded with 250,000 cycles and 50 N with a chewing simulator. All test specimens had 1.5 mm sections taken from their roots. Then, the push-out test was applied to these sections for bond strength. Data were analyzed by Mann-Whitney U test, Shapiro-Wilk, Kruskal-Wallis's test, and Chi-Square. The statistical significance level was determined as 0.05. RESULTS: The bond strength of all test groups decreased after the cycling loading. The bond strength values of zirconia posts showed a statistically significant difference (p < 0.05). The 10 mm length 1.75 mm diameter posts made of Zirconium had the highest bond strength observed in all control and cyclic loading groups of test specimens (9.74 MPa-6.25 MPa). The PEEK test specimens with a 7 mm length and 1.75 mm diameter showed the weakest bond strength in all control and cyclic loading groups (5.44 MPa-3.37 MPa). The average of the cervical region's bond strength values was statistically significantly higher than the apical region (p < 0.05). CONCLUSION: Within the limitations of this study, one-piece custom-milled Zirconia post-cores appear promising, as they perform well under functional forces, especially in the anterior region. In addition, custom-milled PEKK post-cores might be considered a suitable alternative to prefabricated fiber-reinforced posts.

The effects of different surface treatments applied to milled PMMA denture base material on repair bond strength.

The high cost of CAD/CAM systems and materials is a severe economic burden. Therefore, repair of CAD/CAM PMMA, selecting appropriate repair materials, and surface modifications are clinically important. This study aims to evaluate the shear bond strength of PMMA repair materials after various surface treatments on CAD/CAM PMMA denture base material. For this purpose, a total of 480 CAD/CAM PMMA denture base test specimens were manufactured. Then all test specimens were divided into 6 groups, and different surface treatments were applied. Group A: sandblasting, Group B: 4% hydro fluoric acid, Group C: tungsten carbide bur, Group D: dichloromethane + methyl methacrylate mixture, Group E: dichloromethane and methyl methacrylate, Group F: no surface treatment. Each group is then divided into 4 different subcategories; repair processes were performed using; heat-cured acrylic resin (n:20), auto-polymerized acrylic resin (n:20), gingiva composite (n:20), and CAD/CAM PMMA tooth material (n:20). After repairs, thermal aging was applied to half of the test specimens in each subcategory. The shear bond strength value was measured with a universal test device. Sandblasting group showed the highest surface roughness value in all test specimens (p < 0.001). Heat-cured acrylic resin with sandblasting exhibited the highest bond strength, while the untreated gingiva composite resin exhibited the lowest value. Thermal aging decreased bond strength in all repair materials (p < 0.001). Among the surface treatment groups, sandblasting with Al2O3 particles exhibited the highest surface roughness value and repair bond strength. The application of organic solvents to the surface increased the surface roughness and repair bond strength. Applying dichloromethane and methyl methacrylate monomer separately is more effective than applying it as a mixture. The ideal bonding among repair materials was obtained with heat-cured acrylic resin.

Evaluation of the Bond Strength of Polyetherketoneketone to Dental Ceramic.

PURPOSE: To evaluate the efficacy of different surface treatments on the bond strength of polyetherketoneketone (PEKK) to ceramic materials. MATERIALS AND METHODS: PEKK test specimens were separated into four groups according to surface treatments (group S: sandblasting; group A: acid etching; group SA: sandblasting + acid etching; group C: control). Surface roughness values of PEKK specimens were measured before and after surface treatment. After the prepared PEKK specimens were bonded to lithium-disilicate glass-ceramic specimens with resin cement, they were kept in distilled water at 37°C for 24 h. Half of the specimens in each surface treatment group were thermocycled. All test specimens underwent shear bond strength testing. Failure modes were assessed using light microscopy and SEM. RESULTS: Statistical analysis demonstrated that surface treatments created significant roughness on the PEKK surfaces (p = 0.005). While group S showed the highest roughness values, group A showed the lowest. Of the thermocycled test groups, the sandblasting + acid etching group obtained the highest shear bond strengths. Among the non-thermocycled test groups, the sandblasting surface treatment group achieved the highest shear bond strengths. CONCLUSIONS: The application of surface treatments to enhance the bond strength of PEKK to ceramics has proven to be effective.

Impact of different fixed dental prostheses on radiation dose in helical tomotherapy as measured with metal oxide semiconductor field-effect transistor dosimetry.

OBJECTIVE: This ex vivo study evaluated the effects of different fixed dental prostheses and protective materials on scattered radiation during radiation therapy (RT). STUDY DESIGN: Natural teeth (group NT) and 4 types of prostheses (group BL: bilayer lithium disilicate glass-ceramic; group MZ: monolithic zirconia ceramic; group BZ: bilayer zirconia-based all ceramic; and group BM: bilayer metal-ceramic restorations) were examined in maxillary and mandibular arch phantoms. All groups were divided into 3 subgroups: (1) without protective material over the prostheses; (2) protected with a soft acrylic night guard; and (3) protected with polyvinylsiloxane putty. All groups were irradiated with helical RT at 2 Gy and 6 MV photon energy. Doses were measured internally and externally 3 times on each phantom. Results were significant at P < .05. RESULTS: No statistically significant differences in doses were found between groups NT and BL in either phantom, but these groups were different from the others. The differences between groups BZ and MZ were insignificant. Doses in group BM were significantly larger than all other groups. No significant differences existed between doses with and without protective material. CONCLUSIONS: Doses increased significantly due to scattered radiation from the prostheses with increasing material density. Protective materials had no significant effect on dose.

Prevalence and awareness levels of color blindness among students of faculty of dentistry and dental prosthesis technology program.

Purpose: The aim of this study was to evaluate the prevalence and awareness levels of color blindness among students in a faculty of dentistry and dental prosthesis technology program in two different universities. Materials and methods: A survey of awareness of color blindness among 710 students (males: n=271; females: n=439) in the faculty of dentistry and dental prosthesis technology program of Gazi University and Ankara Medipol University in 2019-2021 was conducted. The color vision status of 442 of the students (males; n=155; females: n=287) was assessed using an online Ishihara color blindness test. The data obtained were subjected to statistical analysis using SPSS. Results: There was no statistically significant difference in the color blindness scores in terms of sex (males: 0.75±0.84; females: 0.64±0.75) (p=0.226). The color blindness scores of the dental prosthesis technology students were statistically higher than those of the faculty of dentistry students (p=0.028). Education year was significantly associated with a compromised ability to identify colors properly (p=0.040). There was no statistically significant difference in terms of awareness levels of color blindness according to the number of years of education (p>0.005). Conclusion: In terms of the prevalence of color blindness, 2.2% of faculty of dentistry and dental prosthesis technology students had a moderate-to-high level of color blindness. Students' awareness of their own color vision status was very low. The educational content of faculty of dentistry and dental prosthesis technology programs on color blindness should be enriched.

The effects of adding fluorescent carbon nanoparticles on various mechanical properties of denture liners.

The aim of this in vitro study was to evaluate the effects of incorporating fluorescent carbon nanoparticles (FCNs) on the hardness, tear, and tensile bond strength of an acrylic-based tissue conditioner and a silicone-based soft denture liner. FCNs added to an acrylic-based tissue conditioner (Viscogel, Dentsply; Group V) and a silicone-based soft denture liner (Ufigel P, Voco; Group U) were divided into subgroups according to the concentrations (Group 0: no water, Group 1: with only water, Group 2: 0.5% FCNs, Group 3: 1% FCNs and Group 4: 10% FCNs) (n=10/per group). Shore A hardness, tear, and tensile bond strength tests were performed. Significant decreases occurred in Groups U2, U3, and U4 compared to the control groups (Groups U0 and U1) in the tear and tensile bond strength test parameters (p<0.025). However, in both types of the tested materials, there were no statistically significant differences among the shore A hardness test results (p>0.025).

Effect of Short-Term Aging on the Flexural Strength of a Novel Experimental CAD/CAM Fiber-Reinforced Composite Material: A Pilot Study.

PURPOSE: To investigate the three-point flexural strength of a novel CAD/CAM fiber-reinforced composite (FRC) material following different aging conditions. MATERIALS AND METHODS: The specimens were randomly assigned to one of five groups based on aging condition: (1) control (no treatment); (2) short-term water storage; (3) thermal degradation with autoclaving; (4) chemical degradation with hydrochloric acid; and (5) chemical degradation with citric acid (n = 10 per group). The specimens in the control group received no treatment. Following each treatment protocol, the three-point bending test was used to calculate the flexural strength. Data were statistically analyzed (α = .05), and scanning electron microscopy (SEM) analysis of the specimens was conducted. RESULTS: No significant differences in flexural strength were observed among the groups (P = .199). In addition, no distinct morphologic differences were detected in the SEM images of the specimens. CONCLUSION: The flexural strength of this novel CAD/CAM FRC material was unaffected by different aging methods.

Surface treatment effects on bond strength of CAD/CAM fabricated posts to root canal dentin.

PURPOSE: To compare the effect of different surface treatments on the bond strength of CAD/CAM fabricated resin-based and prefabricated fiber posts to root canal dentin. METHODS: 160 single-rooted human teeth were selected and received endodontic treatment. The teeth were divided into four groups according to the post material used: (1) Prefabricated fiber-reinforced composite post (Snowpost), (2) CAD/CAM nanoceramic (Cerasmart), (3) CAD/CAM polymer infiltrated ceramic (Vita Enamic) and (4) CAD/CAM resin nanoceramic (Lava Ultimate). Then the posts were randomly assigned into four sub-groups according to the surface treatment method used: (1) Control (no treatment), (2) Laser (Er,Cr:YSGG laser device, Waterlase), (3) Hydrofluoric acid treatment [ 9.6% HF (Pulpdent) for 2 minutes], and (4) Sandblasting (50 µm Al2O3). Following post space preparation, posts were cemented with dual-cure resin cement (Panavia SA cement plus). From each root, five 1 mm-thick slices were obtained. The micropush-out bond strength test was performed for each slice. Data were analyzed by using two-way ANOVA and Tukey HSD tests. The fracture modes were evaluated under a stereomicroscope. Representative specimens were analyzed with SEM following surface treatments. RESULTS: Micropush-out bond strength of posts to dentin was significantly affected by the type of post material (P< 0.05), but not by the surface treatment (P= 0.397). CLINICAL SIGNIFICANCE: Posts manufactured by CAD/CAM could be suitable options for restoration of severely affected endodontically-treated teeth.

Physical characteristics of ceramic/glass-polymer based CAD/CAM materials: Effect of finishing and polishing techniques.

PURPOSE: The aim of this study was to compare the effect of different finishing and polishing techniques on water absorption, water solubility, and microhardness of ceramic or glass-polymer based computer-aided design and computer-aided manufacturing (CAD/CAM) materials following thermocycling. MATERIALS AND METHODS: 150 disc-shaped specimens were prepared from three different hybrid materials and divided into five subgroups according to the applied surface polishing techniques. All specimens were subjected up to #4000 grit SiC paper grinding. No additional polishing has been done to the control group (Group I). Other polishing procedures were as follows: Group II: two-stage diamond impregnated polishing discs; Group III: yellow colored rubber based silicone discs; Group IV: diamond polishing paste; and Group V: Aluminum oxide polishing discs. Subsequently, 5000-cycles of thermocycling were applied. The analyses were conducted after 24 hours, 7 days, and 30 days of water immersion. Water absorption and water solubility results were analyzed by two-way ANOVA and Tukey post-hoc tests. Besides, microhardness data were compared by Kruskal-Wallis and Mann-Whitney U tests (P<.05). RESULTS: Surface polishing procedures had significant effects on water absorption and solubility and surface microhardness of resin ceramics (P<.05). Group IV exhibited the lowest water absorption and the highest microhardness values (P<.05). Immersion periods had no effect on the microhardness of hybrid ceramic materials (P>.05). CONCLUSION: Surface finishing and polishing procedures might negatively affect physical properties of hybrid ceramic materials. Nevertheless, immersion periods do not affect the microhardness of the materials. Final polishing by using diamond polishing paste can be recommended for all CAD/CAM materials.

An Interdisciplinary Approach for Hypoplastic Amelogenesis Imperfecta: A Case Report.

INTRODUCTION: Generally, the appropriate rehabilitation concepts of patients with Amelogenesis Imperfecta (AI) should include a multidisciplinary treatment approach. CASE REPORT: This case report describes full mouth rehabilitation of a patient with AI. A 20 years old woman was referred to our clinic with a chief complaint of tooth discoloration, diastema, unsatisfactory esthetics and slight tooth sensitivity. Clinical, histological and radiographic examination revealed hypoplastic AI. Short crowns, diastema, occlusal wear with exposed dentin in the posterior areas, the lack of contact points, dental caries and discoloration were the other clinical findings. RESULTS: As a result of the periodontal and prosthetic evaluation, gingivectomy and ostectomy were planned, and they followed a full mouth fixed prosthetic restoration. CONCLUSION: There was no complication or complaint in a 3-year follow-up. At the end of this follow-up period, the patient was satisfied with esthetics, function and phonation properties of her prostheses.

Effects of surface treatments on repair bond strength of a new CAD/CAM ZLS glass ceramic and two different types of CAD/CAM ceramics.

We evaluated the effects of three different surface treatments and two different bonding procedures on shear bond strength of resin composites to different computer-aided design/manufacturing (CAD/CAM) ceramics with or without thermocycling. The test specimens were prepared from three different CAD/CAM ceramics (Group A, IPS e.max CAD; Group B, IPS e.max ZirCAD; Group C, Vita Suprinity). They were divided into eight subgroups according to the surface treatment and bonding procedures. After resin composite was applied to the surfaces of all test specimens, they were stored in distilled water for 24 h at 37°C. Next, half of the test specimens were subjected to a thermocycling procedure, and the other half were stored in distilled water at 37°C throughout thermocycling. The shear bond strength was performed using a universal testing machine. Statistical analysis revealed that the ceramic types (P > 0.0031) and thermocycling (P > 0.0021) did not, but the surface treatment technique did significantly affect the shear bond strength values (P < 0.05; except group C). Higher bond strength values were observed with HF etching in Groups A and C compared with the other tested surface treatments.

The effects of adding various ratios of zirconium oxide nanoparticles to poly(methyl methacrylate) on physical and mechanical properties.

The aim of the present study is to evaluate the transverse strength, modulus of elasticity, surface roughness, hardness, and water sorption/solubility of nanoparticle zirconium oxide (nano-ZrO2) added to heat-cured poly(methyl methacrylate) (PMMA) after thermocycling. The specimens were divided into four groups according to the ratio of nano-ZrO2 addition to heat-cured PMMA; group 1: 5% nano-ZrO2; group 2: 10% nano-ZrO2; group 3: 20% nano-ZrO2, and group 4 (control): PMMA without nano-ZrO2. A statistically significant decrease in transverse strength was observed by all additional rates of nano-ZrO2 compared with group 4 (control; P < 0.025). When hardness results were evaluated, groups 1 and 2 showed statistically higher values compared with groups 3 and 4 (P < 0.025). The surface roughness of group 3 was statistically higher than the other groups (P < 0.025), but it was within the clinically acceptable limits. As the nano-ZrO2 addition rate increased, water sorption/solubility values of the specimens also increased. Although nano-ZrO2 addition had an adverse effect on some mechanical and physical properties of heat-cured PMMA, it increased hardness values, implying that the addition of nano-ZrO2 would contribute positively to some mechanical properties of PMMA denture base material when nano-ZrO2 was homogeneously distributed in PMMA.

Repair bond strength of resin composite to bilayer dental ceramics.

PURPOSE: The purpose of this study was to investigate the effect of various surface treatments (ST) on the shear bond strength of resin composite to three bilayer dental ceramics made by CAD/CAM and two veneering ceramics. MATERIALS AND METHODS: Three different bilayer dental ceramics and two different veneering ceramics were used (Group A: IPS e.max CAD+IPS e.max Ceram; Group B: IPS e.max ZirCAD+IPS e.max Ceram, Group C: Vita Suprinity+Vita VM11; Group D: IPS e.max Ceram; Group E: Vita VM11). All groups were divided into eight subgroups according to the ST. Then, all test specimens were repaired with a nano hybrid resin composite. Half of the test specimens were subjected to thermocycling procedure and the other half was stored in distilled water at 37℃. Shear bond strength tests for all test specimens were carried out with a universal testing machine. RESULTS: There were statistically significant differences among the tested surface treatments within the all tested fracture types (P<.005). HF etching showed higher bond strength values in Groups A, C, D, and E than the other tested ST. However, bonding durability of all the surface-treated groups were similar after thermocycling (P>.00125). CONCLUSION: This study revealed that HF etching for glass ceramics and sandblasting for zirconia ceramics were adequate for repair of all ceramic restorations. The effect of ceramic type exposed on the fracture area was not significant on the repair bond strength of resin composites to different ceramic types.

Comparative color and surface parameters of current esthetic restorative CAD/CAM materials.

PURPOSE: The purpose of this study was to derive and compare the inherent color (hue angle, chroma), translucency (TPSCI), surface gloss (ΔE*SCE-SCI), and surface roughness (Ra) amongst selected shades and brands of three hybrid CAD/CAM blocks [GC Cerasmart (CS); Lava Ultimate (LU); Vita Enamic (VE)]. MATERIALS AND METHODS: The specimens (N = 225) were prepared into square-shaped (12 × 12 mm2) with different thicknesses and shades. The measurements of color, translucency, and surface gloss were performed by a reflection spectrophotometer. The surface roughness and surface topography were assessed by white light interferometry. RESULTS: Results revealed that hue and chroma values were influenced by the material type, material shade, and material thickness (P < .001). The order of hue angle amongst the materials was LU > CS > VE, whereas the order of chroma was VE > CS > LU. TPSCI results demonstrated a significant difference in terms of material types and material thicknesses (P ≤ .001). TPSCI values of the tested materials were ordered as LU > CS > VE. ΔE*SCE-SCI and Ra results were significantly varied amongst the materials (P < .001) and amongst the shades (P < .05). The order of ΔE*SCE-SCI amongst the materials were as follows LU > VE ≥ CS, whereas the order of Ra was CS ≥ VE > LU. CONCLUSION: Nano-ceramic and polymer-infiltrated-feldspathic ceramic-network CAD/CAM materials exhibited different optical, inherent color and surface parameters.

Functional denture soft liner with antimicrobial and antibiofilm properties.

BACKGROUND/PURPOSE: Denture soft liners, especially used for elders who have poor disinfection habits, provide a favourable environment for accumulation and colonization of microorganisms. This in vitro study is aimed to investigate the effectiveness of natural carvacrol incorporation into soft lining material on the inhibition of oral pathogens. MATERIALS AND METHODS: Antimicrobial susceptibility of carvacrol was primarily determined by disc diffusion method. Soft lining material was prepared as recommended by the manufacturer and 10 µL carvacrol was added aseptically to the soft liner discs. Inhibition zones for the control discs without carvacrol (C) and carvacrol-incorporated discs (CL) were determined by disc diffusion method. The biofilm inhibition percentages of carvacrol on soft liner was determined by MTT assay and also observed by Scanning Electron Microscopy (SEM). RESULTS: Carvacrol displayed great antimicrobial activity for yeast, Gram-negative and Gram-positive strains. The highest inhibition zone of carvacrol (41.33 ± 1.53 mm) was measured for Bacillus subtilis strain which is followed by Candida albicans and Streptococcus sanguis (34.00 ± 1.73 mm and 32.33 ± 0.58 mm, respectively). The inhibition zones were also similar for soft liner discs with carvacrol, with the highest inhibition zones against B. subtilis, Streptococcus mutans and C. albicans (43.67 ± 0.58 mm, 40.33 ± 0.58 mm and 38.33 ± 1.15 mm, respectively). Incorporation of carvacrol into the soft liner decreased (98.03 ± 0.2%) of the biofilm formation for C. albicans. CONCLUSION: Carvacrol-incorporation obviously decreased the colonization and plaque formation of oral pathogens, especially C. albicans accumulation. Carvacrol may be useful as a promising agent for antibacterial and antifungal management for denture soft lining materials.

Load-bearing capacity of novel resin-based fixed dental prosthesis materials.

To evaluate the influence of different materials on the load-bearing-capacity of inlay-retained fixed-dental-prosthesis (FDP). Ten types of FDPs were evaluated (n=7/group): Group PEEK: CAD-CAM polyetheretherketone (PEEK-TechnoMed), Group RC, made of discontinuous-fiber-composite (EverX Posterior); Group FRC1, made of discontinuous-fiber-composite (EverX Posterior) with two-bundles of continuous-unidirectional fiber-reinforced-composite (FRC) (Everstick C&B); Group FRC2, made of discontinuous-fiber-composite (EverX Posterior) with two-bundles of continuous-unidirectional-FRC (Everstick C&B) covered by two-pieces of short-unidirectional-FRC (Everstick C&B) placed perpendicular to the main-framework; Group FB, CAD-CAM fiber-block (Fibra-Composite Bio-C); Group PMMA, CAD-CAM polymethyl methacrylate block (Temp basic); Group RP, resin-paste; Group FRP1, made of resin-paste (G-Fix) with two-bundles of continuous-unidirectional-FRC (Everstick C&B); Group FRP2, made of resin-paste (G-Fix) two-bundles of continuous-unidirectional-FRC covered by two-pieces of short unidirectional-FRC placed perpendicular to the main-framework and Group exp-FRC, experimental CAD-CAM FRC. The bridges were statically-loaded until fracture. Fracture modes were visually examined. ANOVA revealed that significant differences were observed between FDP-materials (p<0.05). In addition, fiber addition to the framework significantly affected load-bearing-capacity (p<0.05).

Does artificial aging affect mechanical properties of CAD/CAM composite materials.

PURPOSE: The purpose of this study was to determine the flexural strength and Weibull characteristics of different CAD/CAM materials after different in vitro aging conditions. METHODS: The specimens were randomly assigned to one of the six in vitro aging conditions: (1) water storage (37°C, 3 weeks), (2) boiling water (24h), (3) hydrochloric acid exposure (pH: 1.2, 24h), (4) autoclave treatment (134°C, 200kPa, 12h), (5) thermal cycling (5000 times, 5-55°C), (6) cyclic loading (100N, 50,000 cycles). No treatment was applied to the specimens in control group. Three-point bending test was used for the calculation of flexural strength. The reliability of the strength was assessed by Weibull distribution. Surface roughness and topography was examined by coherence scanning interferometry. Evaluated parameters were compared using the Kruskall-Wallis or Mann-Whitney U test. RESULTS: Water storage, autoclave treatment and thermal cycling significantly decreased the flexural strength of all materials (p<0.05), whereas HCl exposure or cyclic loading did not affect the properties (p>0.05). Weibull moduli of Cerasmart™ and Lava™ Ultimate were similar with control. Vita Enamic® exhibited similar Weibull moduli in all aging groups except the HCl treated group (p>0.05). Ra values of Cerasmart™ and Lava™ Ultimate were in the range of 0.053-0.088µm in the aged groups. However Ra results of Vita Enamic® were larger than 0.2µm. CONCLUSIONS: Flexural strength of newly developed restorative CAD/CAM materials was significantly decreased by artificial aging. Cyclic loading or HCl exposure does not affect to the flexural strength and structural reliability of Cerasmart™ and Lava™ Ultimate.

Light Transmission of Novel CAD/CAM Materials and Their Influence on the Degree of Conversion of a Dual-curing Resin Cement.

PURPOSE: To evaluate the light transmission characteristics of different types, shades, and thicknesses of novel CAD/CAM materials and their effect on the degree of conversion (DC) of a dual-curing resin cement. MATERIALS AND METHODS: Square specimens (12 × 12 mm2) of three CAD/CAM materials - GC Cerasmart, Lava Ultimate, Vita Enamic - of different thicknesses (1.00, 1.50, and 2.00 mm, n = 5 per thickness) were irradiated with an LED unit. The amount of transmitted light was quantified. Thereafter, the DC% of the dual-curing resin cement (RelyX Ultimate) was recorded after 15 min using Fourier transform infrared spectroscopy. Statistical analysis was performed using two-way ANOVA followed by the Tukey's HSD post-hoc test at a significance level of p < 0.05. Regression analysis was performed to investigate the correlation between the DC and radiant energy, and the DC and thickness. RESULTS: Although the type and shade of CAD/CAM material significantly affect transmitted light irradiation (p < 0.0001), degrees of conversion are similar when the CAD/CAM material or material shade were taken into consideration (p > 0.05). Conversely, material thickness significantly affected light transmission (p < 0.0001) and DC (p < 0.0001). Multiple effects of material, shade, and thickness did not significantly affect the evaluated parameters (p = 0.638 for light irradiation; p = 0.637 for DC). Linear regression analysis showed a correlation between delivered energy and DC% results of the Vita Enamic (R²â€¯= 0.4169, p < 0.0001). CONCLUSION: Reduced light transmission in 2-mm-thick specimens of all CAD/CAM materials indicates that proper curing of the cement beneath CAD/CAM materials should be ensured.