Shofu Block HC Research Articles

Bonding effectiveness of multi-step adhesive resin cements to CAD/CAM blocks: impact of thermal cycling and surface treatment methods

BackgroundTo investigate the effects of thermal cycling and surface treatment methods on the bonding effectiveness of multi-step resin cements to CAD/CAM blocks.MethodsA total of 198 slices, 66 each from CAD/CAM blocks (feldspathic ceramic: Vitablocs TriLuxe Forte, V; resin matrix ceramics (RMCs): Cerasmart, C; and Shofu Block HC, S), were obtained and randomly divided into two subgroups for etching with hydrofluoric acid (HFA) and sandblasting with Al2O3 (SB). After the surface treatments, one etched and one sandblasted sample of each CAD/CAM block was observed via SEM analysis at 500× magnification. The remaining 32 etched and 32 sandblasted samples of each CAD/CAM block were divided into two subgroups to be cemented with total-etch (TE) and self-etch (SE) resin cements. Then, half of the 16 samples in all the subgroups were subjected to aging (TC) for 5000 cycles (n = 8). The shear bond strength (SBS) of each sample was measured. Four-way analysis of variance (ANOVA) and Tukey tests were used to analyze the data (p < 0.05).ResultsWith or without TC, the highest SBS values for V were obtained with the HFA-TE and HFA-SE interactions, respectively. C presented the highest SBS values with HFA-SE and SB-TE interactions, whereas S presented the highest SBS values with SB-TE and HFA-TE interactions. Except the SB-SE interaction, C presented lower SBS values after TC than other materials. HFA created less porosity on the C and S surfaces than V. SB visibly roughened the surfaces of all the materials but caused fractures, cracks, and damage to the surfaces.ConclusionSimilar SBS values can be achieved between feldspathics, RMCs, and multi-step adhesive resins with both HFA and SB treatments. However, the SBS values obtained from the SB-SE interaction may be below the recommended threshold values for all materials after TC. SB can cause distinctive cavities, fissures, and damage, especially on the surfaces of RMCs.

Effect of laser irradiation during in-office tooth bleaching on surface properties of resin-based restorative materials.

This study evaluated the changes in surface properties of three resin-based restorative materials after two laser-assisted, in-office tooth bleaching protocols using erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG) or diode (980nm) lasers. A nanohybrid composite (Enamel Plus HRi), a Bis-GMA-free composite (Enamel Plus HRi Bio Function), and a resin-matrix CAD-CAM ceramic (Shofu Block HC) were tested. Forty specimens for each material were prepared and divided into four groups (n=10/group). The control specimens did not undergo any bleaching treatment, whereas group 2 received bleaching with 40% hydrogen peroxide (H2O2), while groups 3 and 4 underwent the same bleaching procedure with the use of diode (980nm) or Er,Cr:YSGG lasers, respectively. Surface microhardness and roughness measurements were conducted using a Vickers tester and an optical profilometer. Microhardness was lower in bleached specimens, with the nanohybrid composite exhibiting the largest difference from the no bleaching group. For the Bis-GMA-free composite the microhardness difference between no bleaching and laser-assisted bleaching were smaller than seen for the conventional bleaching technique. Surface roughness was higher in bleached specimens, with nanohybrid composite showing the largest differences from the control specimens. The examined laser-assisted tooth bleaching protocols were found not to impact surface microhardness and roughness of the tested resin-based specimens and they are deemed suitable for clinical use.

The Effect of Micromechanical Surface Preparation and Adhesive Surface Modification Strategies on Resin-Matrix Ceramic Repair Bond Strength Using Universal Adhesive Containing Silane Agent

Abstract Objectives This research assesses the effect of the different micromechanical surface preparations and chemically adhesive surface modification strategies applied to resin-matrix ceramics (Shofu Block HC) repaired using resin composites. Materials and Methods Eighty resin-matrix ceramics were conducted and designed into eight groups of 10 specimens and surface treated with (1) micromechanical preparation with sandblast (SB) or hydrofluoric acid (HF), and (2) chemically adhesive techniques with HC primer (HC) and/or silane (Si) and/or conventional adhesive (AD) or universal adhesive (UA) designing are as follows: group 1, SB + HC; group 2, SB + HC + AD; group 3, SB + HC + Si + AD; group 4, SB + HC + UA; group 5, HF + HC; group 6, HF + HC + AD; group 7, HF + HC + Si + AD; and group 8, HF + HC + UA. An ultradent model was put on the specimen center, then filled resin composite. Mechanical testing instrument was used to determine the samples' microshear bond strength (MSBS). To inspect failure modes, a stereomicroscope was used for observing the debonded surfaces. Statistical Analysis To assess the data, a one-way analysis of variance was employed, and the significant level (p &lt; 0.05) was established with Tukey's test. Results Group 3 (29.29 ± 2.58 MPa) and group 4 (28.34 ± 1.26 MPa) demonstrated the two maximum MSBS values. The minimum MSBS (10.02 ± 3.31 MPa) was discovered by group 5. Nevertheless, group 2's MSBS values (22.78 ± 2.44 MPa) differed significantly from the values for groups 3 and 4. All the fractured samples in groups 1, 5, 6, 7, and 8 had an adhesive failure pattern. Furthermore, group 3 presented the greatest mixed failures (40%). Conclusion The SB is the most effective protocol for producing micromechanical retention. The application of HC primer and Si agent prior to the adhesive agent is the best chemical adhesive strategy for sandblasted resin-matrix ceramic surfaces. Additionally, the application of HC primer before the use of UA containing acid-resistant Si is the best alternative chemical adhesive strategy for improving the MSBS.

Different surface treatments on recently introduced CAD-CAM resin-modified ceramics: Implications on bond strength

Statement of problemThe diverse chemical composition of recently introduced resin-modified ceramics complicates the establishment of a universally accepted clinical bonding protocol. PurposeThe purpose of this in vitro study was to evaluate the influence of different surface treatments of resin-modified ceramics on the bond strength to a resin cement. Material and methodsSixteen 10×12×3-mm resin-modified ceramic slices were obtained from each material (Cerasmart; GC, Shofu Block HC; Shofu, Vita Enamic; Vita, Evolux hybrid; BlueDent, Alium; Alium). Slices were assigned to 4 groups based on surface treatments: Control (no treatment), airborne-particle abrasion with Al2O3 (Al2O3), conditioning with 9% HF (HF), and Al2O3+HF. After treatments and silane coupling agent (Monobond N; Ivoclar) application, 7 resin cement cylinders (Choice 2 veneer; Bisco) were built on each slice and light polymerized for 20 seconds. Half of the specimens (n=14 cylinders) were stored for 24 hours, and the other half were thermocycled (20 000 cycles, 5 °C to 55 °C, 30-second dwell time). Microshear bond strength was tested and analyzed with 3-way ANOVA and the Tukey HSD test (α=.05), and failure patterns were classified. Surface morphology after treatments was observed with scanning electron microscopy and Raman spectroscopy. ResultsAfter 24 hours, all treatments induced higher bond strength (P<.05) than in the control in Evolux. Al2O3+HF caused higher bond strength (P<.05) than in the control in Cerasmart and Shofu, and higher bond strength than Al2O3 in Cerasmart. However, it resulted in lower bond strength (P<.05) than Al2O3 in Alium. After thermocycling, irrespective of the resin-modified ceramic, all treatments induced higher bond strength (P<.05) than in the control. HF induced lower bond strength (P<.05) than Al2O3 in Alium. Al2O3+HF caused the highest bond strength (P<.05) in Evolux and higher bond strength (P<.05) than HF in Vita Enamic. Adhesive failures were prevalent under control conditions, and mixed failures were common after treatments. Al2O3 induced surface alterations in all resin-modified ceramics. HF notably altered Vita Enamic, while it had no noticeable impact on the other resin-modified ceramics. Al2O3+HF caused a considerable alteration in Vita Enamic and modified the other resin-modified ceramics. Vita Enamic had the characteristic vibrational bands of inorganic compounds, while the other resin-modified ceramics exhibited distinct bands associated with organic compounds. ConclusionsAirborne-particle abrasion with Al2O3 followed by HF yielded the highest bond strength, regardless of the resin-modified ceramic, except for Alium, which demonstrated better bond strength after airborne-particle abrasion with Al2O3. 9% HF for 30 seconds caused notable surface alterations in Vita Enamic, negatively impacting its bond strength. Vita Enamic was the only resin-modified ceramic displaying both organic and inorganic composition, while the other resin-modified ceramics showed predominantly organic composition.

The Effect of Different Chemical Surface Treatments on the Bond Strength of Resin-Matrix Ceramic Repaired with Resin Composite.

This study investigates the effect of different chemical surface treatment protocols with different functional monomers of universal adhesives on the shear bond strength between resin-matrix ceramic and resin composite. Eighty resin-matrix ceramics (Shofu block HC) were built and designed into eight groups of ten specimens and surface treated with HC primer (HC) and/or three universal adhesives (single bond universal [SBU], Scotchbond universal plus [SBP], and Tetric N-bond universal [TNU]) assigning follows; group 1, nonsurface treated; group 2, HC; group 3, SBU; group 4, HC + SBU; group 5, SBP; group 6, HC + SBP; group 7, TNU; group 8, HC + TNU. A template was put on the specimen center, and then pushed packable resin composite. Mechanical testing machinery was used to examine the samples' shear bond strength (SBS) values. To examine failure patterns, the debonded specimen surfaces were examined by a stereomicroscope. The one-way analysis of variance method was used to evaluate the data, and the Tukey's test was used to determine the significant level (p < 0.05). The highest SBS was obtained in group 6 (39.25 ± 1.65 MPa). Group 1 (4.15 ± 0.54 MPa) had the lowest SBS. Group 6 exhibited the highest percentage of cohesive failure patterns (70%). High SBS values were frequently correlated with the surface treatment groups and the cohesive failure patterns. The application of HC primer prior to the universal adhesive is an alternative protocol for enhancing the repair bond strength between resin-matrix ceramic and resin composite interfaces. Moreover, the application of HC primer prior to the SBP is the best strategy for resin-matrix ceramic and resin composite repairs.

Bacterial adhesion and surface properties of computer-aided design-computer-aided manufacturing restorative materials.

This study aimed to evaluate the surface properties and bacterial adhesion of computer-aided design-computer-aided manufacturing (CAD-CAM) restorative materials. Four CAD-CAM resin-based blocks (Vita Enamic, Shofu block HC, Cerasmart [CS] and Lava Ultimate [LU]) and a leucite-reinforced glass ceramic block (IPS Empress CAD) were used in the present study. Specimens prepared with dimensions of 10 × 10 × 1 mm were polished. Surface characteristics were assessed with hydrophobicity and surface free energy (SFE) analysis. Surface roughness was measured using a profilometer, and elemental and topographic evaluations were performed with SEM-EDX analysis. After being kept in artificial saliva for 1 h, Streptococcus mutans (S. mutans) and Streptococcus mitis (S. mitis) were incubated separately in 5% CO2 atmosphere at 37°C for 24 h. The adhered bacteria were counted as ×108 CFU/mL. Surface roughness, contact angle and SFE measurement values were found to be in the range of 0.144-0.264 Ra, 28.362°-70.074° and 39.65-63.62 mN/m, respectively. The highest adhered amount of S. mutans was found in CS and the lowest in LU, while there was no significant difference between the amounts of adhered S. mitis. Despite differences in the surface properties of the materials used for the study, the materials exhibited identical properties with respect to bacterial adhesion.

Comparative Bonding Analysis of Computer-Aided Design/Computer-Aided Manufacturing Dental Resin Composites with Various Resin Cements

The use of dental resin composites adapted to computer-aided design/computer-aided manufacturing (CAD/CAM) processes for indirect tooth restoration has increased. A key factor for a successful tooth restoration is the bond between the CAD/CAM composite crown and abutment tooth, achieved using resin-based cement. However, the optimal pairing of the resin cement and CAD/CAM composites remains unclear. This study aimed to identify the optimal combination of a CAD/CAM composite and resin cement for bonding. A commercial methyl methacrylate (MMA)-based resin cement (Super-Bond (SB)) and four other composite-based resin cements (PANAVIA V5; PV, Multilink Automix (MA), ResiCem EX (RC), and RelyX Universal Resin Cement (RX)) were tested experimentally. For the CAD/CAM composites, a commercial polymer-infiltrated ceramic network (PICN)-based composite (VITA ENAMIC (VE)) and two dispersed filler (DF)-based composites (SHOFU BLOCK HC (SH) and CERASMART300 (CE)) were used. Each composite block underwent cutting, polishing, and alumina sandblasting. This was followed by characterization using scanning electron microscopy, inorganic content measurement, surface free energy (SFE) analysis, and shear bond strength (SBS) testing. The results demonstrated that the inorganic content and total SFE of the VE composite were the highest among the examined composites. Furthermore, it bonded highly effectively to all the resin cements. This indicated that PICN-based composites exhibit unique bonding features with resin cements. Additionally, the SBS test results indicated that MMA-based resin cement bonds effectively with both DF- and PICN-based composites. The combination of the PICN-based composite and MMA-based resin cement showed the best bonding performance.

Aging and Fracture Resistance of Implant-Supported Molar Crowns with a CAD/CAM Resin Composite Veneer Structure.

Chipping of implant-supported molar crowns (iSCs) is a frequently reported complication. This study aimed to investigate the in-vitro aging and fracture resistance of iSCs with a CAD/CAM resin composite veneer structure fabricated with the Rapid Layer Technology (RLT) approach. Eight iSCs per group were fabricated by using two different CAD/CAM resin composites (Shofu Block HC: SH; Grandio blocs: GB) for veneer structures, and zirconia (ZrO2), polyetheretherketone (PEEK), and cobalt-chromium (CoCr; control) as framework materials. The surfaces to be bonded were sandblasted, cleaned in an ultrasonic bath, and a coupling agent was applied. A self-adhesive resin luting composite was used to adhesively lute the veneer structures to the frameworks. The crowns were semi-permanently cemented to the abutments. After storage in deionized water, iSCs were loaded in a chewing simulator (TCML, 10,000 thermal cycles 5 °C to 55 °C for 20 s, 1.2 million, loading force 50 N). Four ZrO2 and one CoCr crown did not survive the TCML. The fracture force was determined after 24 h storage in deionized water and yielded values of ≥974 N. Lowest fracture forces were yielded in the PEEK-SH group in comparison to CoCr or ZrO2 groups (p ≤ 0.031). For identical framework materials, no significant influence of the veneering material was observed. All PEEK-GB frameworks fractured, and chipping occurred for ZrO2-SH and all CoCr frameworks. PEEK-SH and ZrO2-GB presented both chipping and framework fractures. Within the limitations of this in-vitro study, the RLT with a CAD/CAM resin composite veneer structure might be a promising approach to veneer iSCs. Yet, the choice of the CAD/CAM resin composite and of the framework material determine the fracture resistance.

Influence of surface treatments and adhesive protocols on repair bond strength of glass-matrix and resin-matrix CAD/CAM ceramics.

To specify the effects of self-etching ceramic primer, Monobond Etch and Prime (MEP), and universal adhesive (UA) on repair bond strength between CAD/CAM blocks and resin composite. Vita Mark II (VM), IPS e.max CAD (EMAX), Shofu Block HC (SHC), and Tetric CAD (TET) blocks were sliced and thermocycled. They were divided into four groups according to surface treatments (n = 24): control, sandblasting (AL), hydrofluoric acid etching (HF), and MEP application. SEM analysis assessed surface topography. Subdivided, specimens followed distinct adhesive protocols (n = 12): control (silane + adhesive [SA] or adhesive [A] only for MEP group) and UA. Microshear bond strength (μSBS) was measured following resin composite repair. Data were analyzed using two-way ANOVA and Tukey tests (p < 0.05). The μSBS of CAD/CAM blocks was significantly influenced by surface treatment type and adhesive protocol. The highest μSBS values for each block, considering surface treatment + adhesive protocol, were VM, HF + SA, or HF + UA; EMAX, MEP + A; and SHC and TET, AL + SA, or AL + UA. Except for EMAX, it was not the adhesive protocol that made the significant difference in bond strength for each CAD/CAM block, but the surface treatment. MEP + UA application on glass ceramics lowered μSBS values significantly, so it is not recommended in clinical conditions. Repair is an essential therapeutic option, particularly in esthetic restorations, to swiftly repair the impaired esthetics caused by fracture. Repair protocol is dependent on the restorative material, and to have a reliable repair bond strength, the following surface treatment and adhesive protocol combinations are recommended for each CAD/CAM block: VM, HF + SA, or HF + UA; EMAX, MEP + A; and SHC and TET, AL + SA, or AL + UA.

Performance of direct and indirect onlay restorations for structurally compromised teeth

Research is lacking on the restoration of structurally compromised posterior teeth using direct composite resin or indirect restorations. The purpose of this in vitro study was to measure the fracture resistance and microleakage of different onlay restorations fabricated by using conventional and digital computer-aided design and computer-aided manufacturing (CAD-CAM) to restore structurally compromised teeth. Mandibular molars (n=54) were prepared for onlay restorations. Teeth were allocated to 3 groups (n=18) according to the type of restoration materials, nanohybrid composite resin (Grandio blocs), resin hybrid ceramic (SHOFU Block HC), and fiber-reinforced composite resin (everX Posterior). Onlays were bonded using a dual-polymerized adhesive resin cement. All specimens were thermocycled, followed by cyclic loading. Based on the type of investigation conducted, fracture resistance, and microleakage test, each group was then divided into 2 equal subgroups (n=9). The collected data were statistically analyzed with the chi-square of the Fischer exact test (α=.05). Fracture resistance testing revealed a statistically significant difference between groups (P<.001). The fiber-reinforced composite resin demonstrated the highest fracture resistance, with statistically significantly less microleakage compared with the other groups (P=.013). Direct fiber-reinforced composite resin could be considered a suitable alternative to CAD-CAM composite resin for the restoration of structurally compromised teeth.

Shear Bond Strength of Repaired CAD/CAM Resin-Based Composite Materials Submitted to Er:YAG Laser Treatments at Different Powers

This study aimed to investigate the effects of different powers of Er:YAG laser irradiation on the shear bond strength (SBS) of repaired CAD/CAM resin-based composite materials. A total of 180 CAD/CAM resin-based composite specimens (5 × 5 × 2 mm) were obtained (Shofu Block HC—SB; Grandio Blocs—GB). They were allocated into six groups according to surface pretreatment methods: no surface pretreatment (control), hydrofluoric acid (HF), diamond bur and 3 W, 5 W, and 7 W Er:YAG lasers (20 Hz) (n = 15). Silane and universal adhesive were applied. The repair procedure was completed with nano-ceramic composite resin (Ceram-X Sphere TEC-One). The samples were thermocycled for 10,000 cycles (5–55 °C). The SBS was evaluated with a universal test machine (1 mm/min). A 3D optic profilometer was used to assess the surface topography. Statistical analysis was performed with a two-way ANOVA and Bonferroni tests (p &lt; 0.05). For SB samples, HF and diamond bur caused significantly higher SBSs than 3 W and 7 W lasers, while for GB samples, they led to a significantly higher SBS than all laser treatments. For SB samples, the 5 W laser led to the highest SBS, while for GB samples, the 7 W laser caused the highest SBS (p &lt; 0.05). For both blocks, adhesive failure was more common for the 3 W laser, and a decrease in adhesive failures and an increase in mixed failures were observed with increasing laser irradiation. The 3D optic profilometer revealed that smoother surfaces were obtained with the 3 W laser than other laser irradiation at different powers. Pretreatment with increasing Er:YAG laser powers led to similar bond strengths to hydrofluoric-acid- and diamond-bur-treated CAD/CAM resin-based composite materials. A more powerful laser treatment is required to provide a higher bond strength for restorative materials containing a higher inorganic ceramic content.

In vitro evaluation of CAD/CAM composite materials

ObjectivesThe purpose of this in vitro study was to evaluate the microstructural, elemental and mechanical properties of contemporary computer-aided-design/computer-aided manufacturing (CAD/CAM) resin based composite (RBC) materials. MethodsSix CAD/CAM RBC materials [Brilliant CRIOS (Coltene Whaledent AG), Cerasmart (GC), Lava Ultimate (3M ESPE), Tetric CAD (Ivoclar Vivadent), Shofu Block HC (Shofu), Grandio Blocs (VOCO GmbH)] were tested. Ten rectangular blocks (14 Χ 12 Χ 18 mm) for each material, after metallographic grinding and polishing, were subjected to Instrumented Indentation Testing (ΙIT). Martens Hardness (HM), Indentation Elastic Modulus (EIT), Elastic (ηIT) and Creep indices (CIT) were determined according to formulas provided by ISO 14577. The diagonal length of each indentation was measured and HV was determined. The results of HM, EIT, ηΙΤ, HV, and CIT were statistically analyzed by one-way ANOVA and Tukey post hoc test employing the material as a discriminating variable (a = 0.05), while the possible correlations were determined by Spearman's correlation test. One specimen from each group was examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). ResultsBackscattered Electron images and EDX analysis demonstrated differences in size, shape and type of fillers along with elemental composition among materials tested. Statistical significant differences were identified for all mechanical properties tested. Grandio Blocs had the significantly higher HM (953±7 N/mm2), HV (136±1) and EIT (23±1 GPa) followed by Lava Ultimate (ΗM=674±25 N/mm2, HV=105±2, EIT=15±1 GPa). Elastic index ranged from 41% to 52%, with Shofu Block demonstrating the significantly highest ηIT (52 ± 1%) values. Cerasmart had significantly higher CIT value (8.4 ± 0.1%) than all other materials tested, while Grandio Blocs and Lava Ultimate had the lowest ones. Spearman's correlation revealed that all mechanical properties tested exhibited correlations with each other, apart from ηΙΤ. ConclusionsThe results showed that the CAD/CAM materials tested have differences in their microstructure, elemental composition and mechanical properties. Clinical significanceThe RBCs tested showed significant differences in mechanical properties and thus differences in clinical performance are anticipated. RBCs with increased filler loading had the most favorable combination of hardness, elastic modulus and creep index indicating that these materials may have better clinical performance under intraoral loading conditions.

Wear characteristics of esthetic resin matrix and zirconia reinforced lithium disilicate CAD/CAM materials: two-body wear and surface topography analysis.

This in vitro study assessed the wear behavior of different CAD-CAM blocks and the abrasion of the enamel antagonist against these materials. 64 disk-shaped specimens were prepared from 8 different CAD/CAM blocks as follow: one lithium disilicate glass ceramics block "IPS Emax CAD" as control group, two zirconia reinforced lithium silicate "Vita Suprinity & Celtra DUO," one interpenetrating network ceramic block "Vita Enamic," Three resin-based block composites "Lava Ultimate, Cerasmart & Brilliant-crios" as well as one hybrid nanoceramic "Shofu block HC". All specimens were mounted against canine and tested for two body wear analysis using a chewing simulating loading machine (100,000 cycles, 50 N, 5/55 °C). The amount of wear loss was measured for each specimen using a digital precise scale. Wear area before and after the chewing simulation were evaluated using an optical profilometer. Data analysed using one-way ANOVA test followed by Tukey's post hoc. The results showed a significantly higher wear loss in resin matrix ceramics in comparison to glass ceramics. However, for tooth wear glass ceramics had significantly higher value than hybrid ceramics. Resin based CAD/CAM Blocks gives a superior result when evaluating the wear behavior and its effect on the opposing tooth surface.

Improving retention of dental veneers fabricated from an experimental enamel-based biopolymer compared with CAD/CAM hybrid materials

ObjectivesCAD/CAM hybrid materials have become increasingly utilized in restorative dentistry. However, their low tensile bond strength (TBS) may lead to the detachment of minimally invasive restorations. When prepared, an experimental enamel-based biopolymer prosthesis provided a honeycomb-like interfacial layer with luting adhesives leading to a higher TBS than Ni–Cr–Be based alloy, lithium disilicate-based ceramic, and cured-resin-composite. This study aimed to compare TBSs of dental veneers fabricated from experimental biopolymer and commercial hybrid materials bonded to enamel using two different luting adhesives. MethodsLaminate veneers (4 × 4 mm) 1 mm thick were prepared from commercial CAD/CAM blocks: VITA ENAMIC, SHOFU Block HC, KATANA AVENCIA, and an experimental biopolymer. The flat bonding surface of the veneers was ground to 600-grit, followed by 50-μm alumina air-abrading for standardization. Each veneer was fixed on flat ground bovine enamel using either Super-Bond C&B or RelyX™ U200 resin (n = 10). The surface treatment and bonding procedures were treated as recommended by the manufacturers. All bonded specimens were stored in water at 37 °C for 24 h before tensile testing with a universal testing machine at a cross-headed speed of 1.0 mm/min. The fractured surface was examined with a stereomicroscope and scanning electron microscope. TBS data were statistically analyzed using two-way ANOVA and Tukey's HSD test (α = 0.05). ResultsExperimental biopolymer veneers demonstrated the highest mean TBS with cohesive failure in the luting agents. Adhesive failure at the veneer side interface was found in other groups. There was no significant difference between the two luting agents. ConclusionThe results indicate that the experimental biopolymer veneer bonded to enamel provided the best retention. The TBS at the enamel-resin interface is higher than at the veneer-resin interface for all commercial CAD/CAM hybrid materials. Clinical significanceAn experimental enamel-based biopolymer veneer can provide better retention than CAD/CAM hybrid materials in clinical treatment.

The influence of different storage media on Vickers hardness and surface roughness of CAD/CAM resin composites

IntroductionThis study examined Vickers hardness as well as surface characteristics of different computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites prior to and after storage in various media.Materials and methodsCAD/CAM resin composite blocks (Grandio Blocs (GB), Lava Ultimate (LU), Brilliant Crios (BC), Cerasmart (GC), Shofu Block HC (SB), Tetric CAD (TC), Luxacam Composite (LC); incl. different translucency variants) were prepared, polished and surface free energy was determined. The specimens were divided into four groups: dry conditions for 24 h (25 °C), demineralized water (37 °C), Pepsi Cola (37 °C) and 75% ethanol (37 °C). After seven and 28 days of storage, Vickers hardness was determined. Surface roughness was measured after the entire storage period.Results and discussionVickers hardness was in the range of about 150 HV for GB, around 115 HV for LU, and 80–100 HV for BC, GC, SB, TC and LC. Only minor differences (total: 50.2 (6.4)–56.2 (3.2) mN/m) in surface free energy could be detected. No relationship was observed between surface free energy and filler content. However, a correlation between filler content and Vickers hardness was evident. Artificial aging caused a decrease of Vickers hardness (up to −40 HV or 35%) depending on storage media, duration and material. The changes in surface texture after immersion in different media were below a value of ΔSa = 0.015 µm.ConclusionArtificial aging of CAD/CAM resin composites leads to a significant decrease of Vickers hardness for most materials, while only small changes in surface roughness were identified.Graphical

Effect of Anti-COVID-19 Mouthwashes on Shear Bond Strength of Resin-Matrix Ceramics Repaired with Resin Composite Using Universal Adhesive: An In Vitro Study

Using anti-COVID-19 mouthwashes has become necessary to reduce acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmissions. Resin-matrix ceramic (RMCs) materials that are exposed to mouthwashes may affect the bonding of repaired materials. This research was performed to assess the effects of anti-COVID-19 mouthwashes on the shear bond strengths (SBS) of RMCs repaired with resin composites. A total of 189 rectangular specimens of two different RMCs (Vita Enamic (VE) and Shofu Block HC (ShB)) were thermocycled and randomly divided into nine subgroups according to different mouthwashes (distilled water (DW), 0.2% povidone-iodine (PVP-I), and 1.5% hydrogen peroxide (HP)) and surface treatment protocols (no surface treatment, hydrofluoric acid etching (HF), and sandblasting (SB)). A repair protocol for RMCs was performed (using universal adhesives and resin composites), and the specimens were assessed using an SBS test. The failure mode was examined using a stereomicroscope. The SBS data were evaluated using a three-way ANOVA and a Tukey post hoc test. The SBS were significantly affected by the RMCs, mouthwashes, and surface treatment protocols. Both surface treatment protocols (HF and SB) for both RMCs, whether immersed in anti-COVID-19 mouthwash or not, improved the SBS. For the VE immersed in HP and PVP-I, the HF surface treatment had the highest SBS. For the ShB immersed in HP and PVP-I, the SB surface treatment had the highest SBS.

Translucency of CAD/CAM and 3D Printable Composite Materials for Permanent Dental Restorations

The aim of the study was to compare the translucency of CAD/CAM and printable composite materials for fixed dental prostheses (FDP). Eight A3 composite materials (7 CAD/CAM and 1 printable) for FPD were used to prepare a total of 150 specimens. CAD/CAM materials, all characterized by two different opacity levels, were: Tetric CAD (TEC) HT/MT; Shofu Block HC (SB) HT/LT; Cerasmart (CS) HT/LT; Brilliant Crios (BC) HT/LT; Grandio Bloc (GB) HT/LT; Lava Ultimate (LU) HT/LT, Katana Avencia (KAT) LT/OP. The printable system was Permanent Crown Resin. 1.0 mm-thick specimens were cut from commercial CAD/CAM blocks using a water-cooled diamond saw, or 3D printed. Measurements were performed using a benchtop spectrophotometer with an integrating sphere. Contrast Ratio (CR), Translucency Parameter (TP), and Translucency Parameter 00 (TP00) were calculated. One Way ANOVA followed by Tukey test for post hoc were performed for each of the translucency system. The tested materials exhibited a wide range of translucency values. CR ranged from 59 to 84, TP from 15.75 to 8.96, TP00 from 12.47 to 6.31. KAT(OP) and CS(HT) showed, respectively, the lowest and highest translucency for CR, TP and TP00. Due to the significant range of reported translucency values, clinicians should exercise caution when choosing the most appropriate material, especially considering factors such as substrate masking, and the necessary clinical thickness.

Effect of aging on color, gloss and surface roughness of CAD/CAM composite materials

ObjectivesTo assess the effect of aging procedures on color, gloss and surface roughness of CAD/CAM composite materials. Methods6 CAD/CAM composite materials (Brilliant CRIOS, Cerasmart, Lava Ultimate, Tetric CAD, Shofu Block HC, Grandio Blocs) were tested. 10 CAD/CAM fabricated specimens of each material polished according to manufacturers’ recommendations, were subjected to one of the following aging procedures; immersion in coffee (30 days, 37οC), water thermocycling (5000 cycles, 5–55 °C) and photoaging (150,000 kJ/m2). Color, gloss and surface roughness measurements were performed before and after aging and the respective changes were calculated. Kruskal-Wallis tests, paired t-tests, one-way ANOVA and Bonferroni post-hoc tests were used for statistical analysis (a = 0.05). ResultsColor changes ranged from 3.03 to 4.13 after coffee immersion, from 1.33 to 2.55 after thermocycling and from 1.02 to 2.75 after photoaging. No statistically significant differences for ΔE*ab were found among materials after coffee immersion and thermocycling (p>0.05). Gloss changes ranged from -5.7 to -1.6 GU after coffee immersion, from -2.3 to 0.1 GU after thermocycling and from -4.4 to 0.5 GU after photoaging. No significant differences in gloss changes were found among materials after aging (p>0.05). Tetric CAD demonstrated the significantly lower gloss and the higher surface roughness after polishing. Except for gloss after thermocycling, aging procedures caused significant alteration of gloss and surface roughness parameters from baseline levels. ConclusionsAging procedures caused perceptible but acceptable color changes and small but visible gloss changes, while surface roughness parameters of the tested CAD/CAM composite materials were significantly affected by aging. Clinical significanceAging procedures affected CAD/CAM composite materials indicating that these materials may be prone to color and surface alterations in the oral environment that could compromise the esthetics and the performance of the restorations. Clinical studies are needed to investigate the long-term behavior of the newly introduced CAD/CAM materials.

The effect of occlusal reduction and different CAD-CAM materials on stress distribution in endocrown restorations: A three-dimensional finite element analysis

Aim: The aim of this study was to examine the effects of various preparation types and restorative materials on endocrown restorations applied to endodontically treated maxillary first molars and the stress distribution on the related tissues. Methodology: A three-dimensional (3D) image of a previously extracted intact tooth was obtained with CBCT. The resulting .dicom files were imported into Mimics. Enamel, dentine, and pulp were separated and extracted as an STL file. Four groups were determined and prepared in SolidWorks. The 3D images were imported into the relevant finite element analysis software (ABAQUS, 2020 Dassault Systems Simulation Corp., Johnston, RI, USA), and a load of 600 N was applied at the occlusal area of each model in the axial direction. Models were divided into three groups according to material type: Vita Suprinity (VS; VITA Zahnfabrik, Bad Sackingen, Germany), Cerasmart (CS; GC Corp., Tokyo, Japan), and Shofu Block HC (SB; Shofu, Kyoto, Japan). The type of cement used was RelyX ARC (3M ESPE, MN, USA). Results: Regardless of the results, stress on any tissue or restoration did not exceed the strength limits. In models with cusp preparation, the stress on the dental tissues was lower. Higher stress was generally observed in groups in which the lingual area was healthy. On the other hand, stress occurring in zirconia-reinforced glass ceramics (VS) is higher than in ceramic materials with a resin matrix (CS, SB). It has been determined that the stress transmitted to the supporting tissues is lower. Conclusion: Endocrown restorations can be used in the restoration of endodontically treated first molars. In addition, when endocrown restoration is applied to molars with only one healthy area and excessive loss of coronal structure, reducing the cusp is beneficial in terms of the distribution of stress on healthy tissues. How to cite this article: Tolu Gİ, Güntekin N, Mohammadi R, Demirel MG. The effect of occlusal reduction and different CAD-CAM materials on stress distribution in endocrown restorations: A three-dimensional finite element analysis. Int Dent Res 2022;12(Suppl.1):22-8. https://doi.org/10.5577/intdentres.461

Effect of Different Surface Treatments on Repair Bond Strength of CAD/CAM Resin-Matrix Ceramics.

The purpose of this study was to investigate the influence of different surface treatment methods on the micro-tensile bond strength (μTBS) of resin-matrix ceramic (RMC) blocks repaired with resin composite. Three different prefabricated RMC blocks including Lava Ultimate (LU), Grandio Blocs (GB), and Shofu Block HC (HC) were thermo-cycled and divided into five surface treatment groups: Control (C), bur grinding (G), airborne particle abrasion (APA), Er,Cr:YSGG laser irritation (LI), and APA combined with LI (APA+LI). After surface treatments, topographic alterations were examined by scanning electron microscopy. Then, Universal Adhesive (Single Bond Universal) was applied and repair was simulated with nanohybrid composite (Grandio SO). Bonded specimens were cut into 1 mm2 sized beams (n = 16) and a μTBS test was conducted by using a universal test machine. Fracture types were evaluated by using a stereomicroscope. The bond- strength data was evaluated by two-way ANOVA and Tukey post-hoc test (α = 0.05). The μTBS values were significantly affected by the surface treatment variable and the interaction terms of the variables (p ≤ 0.001). However, no significant effect of RMC type was detected (p > 0.05). Among all materials, GBAPA+LI indicated the highest µTBS value. Except for the GBC, all surface treatments showed clinically acceptable bond-strength values. However, the surface treatments applied to GB and LU before the repair processes increased the repair bond-strength values while causing a negative effect for HC. In addition, LI and APA+LI can be applied as an alternative route compared to other procedures recommended by the manufacturer for surface preparation in intraoral RMC repair.