Comparison of surface properties of universal shade and conventional resin-based composites after degradation and repolishing.

PURPOSE: To investigate the discoloration, line roughness and gloss of conventional and universal shade resin-based composites. METHODS: Clearfil AP-X (AP-X) and Estelite Sigma Quick (EQ) samples were prepared. Discoloration, roughness, and gloss were measured on mirror-polished, alkaline-degraded, and repolished surfaces. The superficial layer degraded by alkaline immersion (degraded layer) was ground off from the sample surface. After removing the degraded layer, the surface was polished with aluminum oxide powder (1.0 µm and 0.3 µm), to create a repolished specimen. Scanning electron microscopy observations were made of the specimens. RESULTS: The results were compared with those for Omnichroma (OC) from a previous study. All the materials showed different responses to degradation and repolishing, but repolishing of AP-X, for surface roughness and gloss, was more effective at restoring pre-degradation properties. Repolishing effectively removed discoloration in all materials. CLINICAL SIGNIFICANCE: The materials tested showed different responses to degradation and repolishing, but repolishing of AP-X, for surface roughness and gloss, was more effective at restoring pre-degradation properties. Repolishing effectively removed discoloration in all materials.

Effect of low power Er:YAG laser irradiation of CAD-CAM resin-based composites on resin bonding.

PURPOSE: To investigate the effect of painless low-power Er:YAG laser irradiation of conventional and polymer-infiltrated ceramic network (PICN) type CAD-CAM resin-based composites (RBCs) on resin bonding. METHODS: An Er:YAG laser system, phosphoric acid etchant, universal adhesive, RBC, and two types of CAD-CAM RBC block were used. Microtensile bond strength, fracture mode, scanning electron microscopy (SEM) observations of bonding interfaces and CAD-CAM surfaces, and surface roughness of ground and pretreated surfaces were investigated. As pretreatment methods, low-power Er:YAG laser irradiation and air-abrasion with alumina particles were used. RESULTS: The effect of low-power Er:YAG laser irradiation of CAD-CAM RBCs on bonding to repair resin varied depending on the type of CAD-CAM RBCs. CLINICAL SIGNIFICANCE: The low-power Er:YAG laser irradiation of the conventional CAD-CAM RBCs was shown to be effective as a surface pretreatment for resin bonding, while the laser irradiation of PICN-type CAD-CAM RBCs was not effective.

Fracture resistance of chairside CAD-CAM lithium disilicate occlusal veneer with various designs after mechanical aging.

PURPOSE: This study evaluated the fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate crown, onlay, and non-anatomical occlusal veneer (A-OV) with and without margin fabricated. MATERIALS AND METHODS: Sixty-four CAD-CAM lithium disilicate restorations were designed as (1) complete coverage crown (CCC); (2) A-OV with margin; (3) non-A-OV with margin (NA-OV-M); and (4) non-A-OV without margin (NA-OV-NM), 16 of each. Restorations were crystallized and adhesively luted to resin dies using resin cement. Specimens were then subjected to 400,000 cycles of chewing in a mastication simulator. A universal testing machine was used to apply a compressive load at a crosshead speed of 1 mm/min to the long axis of the tooth with a stainless-steel sphere until fracture occurred. One-way ANOVA followed by post hoc tests were used to assess the impact of preparation design on the fracture load of CAD-CAM lithium disilicate restorations. RESULTS: The highest fracture load was recorded for CAD-CAM lithium disilicate indirect restorations for non-A-OVs preparation with margin (2549 ± 428 N) and onlay (2549 ± 293 N) and the lowest fracture load was recorded for CCCs (2389 ± 428 N); however, there was no significant (p = 0.640) between groups. CONCLUSIONS: CAD-CAM lithium disilicate restorations fabricated for anatomical and non-A-OV preparation display a fracture resistance similar to CCCs. Conservative partial coverage restorations may be considered an acceptable approach for posterior teeth.

Minimally Invasive Laminate Veneer Therapy for Maxillary Central Incisors.

Minimally invasive dentistry is a considered process that requires the clinician to be prepared with the ideal sequence and the tools needed. This report describes a well-planned ultraconservative approach using only two ceramic laminate veneers for the maxillary central incisors to significantly improve the patient's overall smile. A 30-year-old female presented with the chief complaints of having diastemas between the central and lateral incisors as well as incisal wear. Diagnostic wax-up and mock-up were performed, and the patient approved the minimally invasive treatment with veneers only for central incisors. A reduction guide aided the conservative tooth preparations, and hand-crafted feldspathic veneers were bonded under total isolation with a rubber dam. The two final conservative veneers significantly improved the smile and fulfilled the patient's expectations. Following proper planning and sequencing, predictable outcomes were obtained and fulfilled the patient's esthetic demands. Minimally invasive restorative dentistry with only two single veneers can impact the entire smile frame. Overtreatment in the esthetic zone is unnecessary to meet a patient's esthetic expectations.

Ceramic versus Composite Resin Polishing Systems on the Surface Roughness of Milled Leucite-Reinforced Ceramics.

Background and Objective: This study aimed to compare the surface finish of milled leucite-reinforced ceramics polished with ceramic and composite polishing systems based on the manufacturers' recommendations. Materials and Methods: Sixty subtractive computer-aided manufactured (s-CAM) leucite-reinforced glass-ceramic specimens (IPS-Empress-CAD) were assigned into six groups: no polishing, a ceramic polishing kit, and four composite kit groups. The roughness average (Ra) was evaluated in microns using a profilometer, and scanning electron micrographs were obtained for qualitative analysis. A Tukey HSD posthoc test (α = 0.05) was used to determine significant intergroup differences. Results: After surface evaluation of the ceramics, the Ra values of the polishing systems ranked OptraFine (0.41 ± 0.26) < Enhance (1.60 ± 0.54) < Shofu (2.14 ± 0.44) < Astropol (4.05 ± 0.72) < DiaComp (5.66 ± 0.62) < No Polishing (5.66 ± 0.74). Discussion: Composite polishing systems did not provide as smooth surfaces as the ceramic polishing kit for CAD-CAM leucite-reinforced ceramics. Thus, using ceramic polishing systems, polishing leucite ceramics is recommended, whereas composite polishing systems should not be considered as an alternative for use in minimally invasive dentistry.

Effect of mold enclosure and chisel design on fatigue bond strength of dental adhesive systems.

To examine the effect of mold enclosure and chisel design on macro shear fatigue bond strengths of dental adhesive systems. The fatigue bond strength testing was conducted with two commercially available dental adhesive systems, (1) OptiBond eXTRa and (2) Scotchbond Universal, for bonding a resin composite (Filtek Supreme Ultra) to both enamel and dentin using a mold enclosure and a non-mold enclosure with a knife-edge and two sized notched-edge chisel assemblies for loading. As a loading reference for the fatigue testing, macro shear bond strengths of the adhesive systems to enamel and dentin were conducted using a mold enclosure and a knife-edge chisel assembly. The shear bond strengths with the mold enclosure using knife-edge chisel assembly did not exhibit a significant difference between the adhesive systems for either enamel or dentin. The fatigue bond strengths of bonded specimens demonstrated significant differences when comparing the mold enclosure and non-mold enclosure, but not between knife-edge and notched-edge chisel assemblies. The fatigue bond strengths of dental adhesive systems demonstrated significantly higher values when using mold-enclosed bonded specimens than a non-mold enclosure, regardless of type of chisel assembly.

Immediate bond performance of resin composite luting systems to saliva-contaminated enamel and dentin in different curing modes.

The purpose of this study was to evaluate the immediate shear bond strength of resin composite luting systems to tooth with or without saliva contamination in different curing modes. The Knoop hardness number of the resin composite luting agents was measured. Four combinations of resin composite luting systems were used. The shear bond strength to bovine teeth was measured with and without saliva contamination in different curing modes at different storage periods. The Knoop hardness number of the resin composite luting agents was also evaluated. Significantly lower enamel and dentin shear bond strengths and Knoop hardness number values were observed in all resin composite luting systems at 5 min versus 24 h, regardless of the curing mode or saliva contamination. The influence of the curing mode of the resin composite luting systems on shear bond strengths and Knoop hardness number was dependent on material. For the saliva contamination conditions, only G-CEM ONE EM did not show any significant difference in shear bond strength among the groups with and without saliva contamination, regardless of curing mode, storage period, or tooth substrate. All the resin composite luting systems showed lower shear bond strengths and Knoop hardness number values immediately after setting.

Comparison of Fracture Resistance for Chairside CAD/CAM Lithium Disilicate Crowns and Overlays with Different Designs.

PURPOSE: To determine the fracture resistance of chairside computer-aided design and computer-assisted manufacturing (CAD/CAM) lithium disilicate full coverage crowns and two different designs of overlay restorations for premolars. MATERIALS AND METHODS: CAD/CAM lithium disilicate (IPS e.max CAD for CEREC/HT A1 C14, Ivoclar Vivadent) restorations (15 specimens/group) with 1.5 mm occlusal thickness and 1.0 mm chamfer were designed and fabricated with a chairside CAD/CAM system (CEREC, Dentsply Sirona). The restorations were prepared in three different designs: (1) full coverage crowns, (2) overlays with the margin located 2 mm above the gingiva, and (3) overlays with the margin located 4 mm above the gingiva. Restorations were cemented using conventional resin luting cement (Multilink, Ivoclar Vivadent) with primer system (Monobond Plus, Ivoclar Vivadent) to resin printed dies, load cycled (2,000,000 load cycles at 1 Hz with 275 N force), and then finally loaded with a steel indenter until failure. Scanning electron microscopy observations of fractured surfaces were also conducted. Group results were analyzed with one-way analysis of variance, and the medians were evaluated independently with Kruskal-Wallis. RESULTS: The fracture force of CAD/CAM lithium disilicate restorations was significantly different (p < 0.001) depending on the design of the restoration. Full coverage crowns showed significantly higher force to fracture (1018.8 N) than both types of overlays (p = 0.002 for overlay 2.0 mm and p < 0.001 for overlay 4.0 mm above gingiva). Among the two overlays, the restoration with the margin located 2 mm above the gingiva showed significantly higher fracture force (813.8 N) than the overlay with margin at 4 mm above the gingiva (436.1 N; p < 0.001). The fracture appearance of the crowns was much more complex than that of the overlay restorations. CONCLUSIONS: Full coverage chairside CAD/CAM lithium disilicate premolar crown showed higher fracture resistance than overlay restorations. Overlays with the margin located 2 mm above the margin demonstrated higher resistance than those with the margin located 4 mm above the gingiva.

Diagnostic Mock-Up as a Surgical Reduction Guide for Crown Lengthening: Technique Description and Case Report.

Background and Objectives: The report describes a technique using a diagnostic mock-up as a crown-lengthening surgical guide to improve the gingival architecture. Materials and Methods: The patient's primary concern was improving her smile due to her "gummy smile" and short clinical crowns. After clinical evaluation, surgical crown lengthening accompanied by maxillary central full-coverage single-unit prostheses and lateral incisor veneers was recommended. The diagnostic mock-up was placed in the patient's maxillary anterior region and used as a soft tissue reduction guide for the gingivectomy. Once the planned gingival architecture was achieved, a flap was reflected to proceed with ostectomy in order to obtain an appropriate alveolar bone crest level using the overlay. After six months, all-ceramic crowns and porcelain veneers were provided as permanent restorations. Results: A diagnostic mock-up fabricated with a putty guide directly from the diagnostic wax-up can be an adequate surgical guide for crown-lengthening procedures. The diagnostic wax-up was used to fabricate the diagnostic mock-up. These results suggested that it can be used as a crown-lengthening surgical guide to modify the gingival architecture. Several advantages of the overlay used in the aesthetic complex case include: (1) providing a preview of potential restorative outcomes, (2) allowing for the appropriate positioning of gingival margins and the desired alveolar bone crest level for the crown-lengthening procedure, and (3) serving as a provisional restoration after surgery. Conclusions: The use of a diagnostic mock-up, which was based on a diagnostic wax-up, as the surgical guide resulted in successful crown lengthening and provisional restorations. Thus, a diagnostic overlay can be a viable option as a surgical guide for crown lengthening.

Bond durability of universal adhesives to intact enamel surface in different etching modes.

This study aimed at determining the enamel bond durability of universal adhesives to intact enamel (IE) and ground enamel (GE) in different etching modes under thermal cycling (TC) and fatigue stresses. Two universal adhesives and a two-step self-etch adhesive were used. Enamel specimens were divided into four groups by treatment: (i) GE in etch-and-rinse, (ii) IE in etch-and-rinse, (iii) GE in self-etch, and (iv) IE in self-etch. Bonded specimens were subjected to TC, and then shear bond strengths (SBS) were conducted. SBS tests were also conducted after storage in 37°C water for 24 h (baseline). For shear fatigue strength (SFS) testing, bonded specimens were subjected to fatigue stress at a frequency of 10 Hz for 50,000 cycles. At baseline, all adhesives showed significantly higher SBS values with GE than IE in self-etch mode in contrast to in etch-and-rinse mode. After TC, the universal adhesives with IE showed lower SBS values than the baseline, regardless of the etching mode. Universal adhesives showed significantly lower SFS values with IE in etch-and-rinse, but not in self-etch mode. Phosphoric acid pre-etching or grinding of the aprismatic enamel may be helpful in establishing reliable initial and long-term bonds to enamel when using universal adhesives in self-etch mode.

Bonding and wear properties of self-adhesive flowable restorative materials.

The purpose of this study was to evaluate the bonding and wear properties of self-adhesive flowable restorative materials. Five self-adhesive flowable restorative materials were used. The study parameters were: (i) shear bond strengths; (ii) microleakage; (iii) occlusal wear; and (iv) qualitative evaluation of the bonding interface. The range of shear bond strengths of the materials was as follows: 7.4-12.2 MPa to ground enamel, 22.5-32.5 MPa to etched enamel, and 1.3-4.2 MPa to dentin. The microleakage scores of the materials did not show any statistically significant differences regardless of the presence or absence of etching. The wear facets on the materials showed 0.099-0.447 mm3 of volume loss and 148.6-365.3 µm maximum depth, with statistically significant differences between materials. Scanning electron microscopic images of the interfaces of the materials showed good adaptation regardless of substrate. The bonding and wear properties of self-adhesive flowable restorative materials were still limited and showed lower values than previously reported results for nanofilled composites with an adhesive system. Selective enamel etching can improve the bonding performance of these materials.

Effect of double-layer application on the early enamel bond strength of universal adhesives.

OBJECTIVES: The present study aimed to investigate the changes in the enamel bond strengths of universal adhesives in the early phase of specimen creation and evaluate the effect of double-layer application on enamel bond effectiveness using different etching modes. METHOD: Four universal adhesives, namely Clearfil Universal Bond Quick, G-Premio Bond, Scotchbond Universal, and Tokuyama Universal Bond, were used. Clearfil SE Bond two-step self-etch adhesive system was used as a comparison. Fifteen specimens per group were used for determining the shear bond strength (SBS) to bovine enamel in the etch-and-rinse or self-etch mode. The adhesive was applied to specimens in accordance with the manufacturers' instructions (single-layer application), or the adhesive was applied twice (double-layer application). The bonded specimens were stored in distilled water at 37 °C for 5 min or 1, 6, 12, or 24 h before SBS testing. The flexural properties of the resin composite Clearfil AP-X were measured for the same storage periods. RESULTS: All universal adhesives exhibited increased SBS values with prolonged storage periods regardless of the application technique or etching mode used. Double-layer application was associated with higher SBS values than single-layer application for most universal adhesives over the same storage period. CONCLUSION: Phosphoric acid pre-etching and double-layer application of universal adhesives resulted in increased enamel bond strength in the early phase of specimen bonding. CLINICAL RELEVANCE: Care should be taken when using universal adhesives in the self-etch mode for enamel bonding because the enamel adhesion is sensitive to the duration after filling.

Effect of ion-releasing filler-containing gel application on dentin remineralization using optical coherent tomography.

PURPOSE: To examine the effects of an ion-releasing filler-containing gel on the remineralization of dentin using optical coherence tomography (OCT). METHODS: Dentin slabs of bovine teeth were sliced and shaped into a rectangular form. Specimens were treated with undersaturated 0.1 M lactic acid buffer solution (pH 4.75) for 10 minutes and then placed in artificial saliva (pH 7.0). This procedure was repeated three times a day for 28 days. The dentin remineralization effects of a fluoride/S-PRG filler-containing gel (PRG) and a 38% SDF solution (SDF) on dentin slabs of bovine teeth were compared. After treatment, the dentin slabs were immersed in a 0.1 M lactic acid buffer solution and then placed in artificial saliva. This procedure was repeated three times a day for 28 days. OCT imaging was conducted on the selected location of the dentin surface. The peak intensity and width at 1/e² were recorded in each of the six areas on the sample and averaged. Each group had a sample size of 10. Knoop hardness number (KHN) measurements and scanning electron microscopy (SEM) observations were also conducted. The data for each group were subjected to a one-way repeated-measures ANOVA and Tukey tests (α= 0.05). The samples were also observed using SEM. RESULTS: The peak signal intensities of SDF and PRG decreased on day 7 and then slightly increased during the experimental period for the one-off application groups and then decreased for frequent-time application groups. Although the width at 1/e² in the untreated specimens decreased over the test period, SDF and PRG for the one-off application groups exhibited an increase in widths on day 7 followed by a slight decrease, whereas it increased for the frequent-time application groups. The average KHN of the dentin samples exhibited the same tendency as the width at 1/e². Closure of the dentin tubules and crystal precipitation were detected on the surface of both SDF and PRG groups. CLINICAL SIGNIFICANCE: S-PRG filler-containing gel might have the ability to prevent dentin demineralization and could be useful for the prevention of hard-to-access lesions. This material achieved remineralization of the demineralized root dentin and had the same remineralization ability as SDF in vitro.

Influence of light irradiation for in-office tooth whitening: A randomized clinical study.

PURPOSE: To evaluate the influence of light irradiation on the clinical efficiency of an in-office whitening agent. METHODS: The in-office whitening agent (Opalescence Boost 35%) was used in this study. Two whitening regimens were evaluated on maxillary anterior teeth: (1) with light irradiation; and (2) without light irradiation. The ΔE*, changes of L*, a*, b*, and the best shade match on the central incisor before, immediately after, and 6 months after whitening procedures were evaluated using a dental spectrophotometer. RESULTS: The ΔE and shade had no significant differences with or without light irradiation. In addition, the ΔE, changes of L*, a*, b*, and shade did not change over 6 months after bleaching at a level detectable to the naked eye. The results suggested that the in-office whitening agent using 35% hydrogen peroxide without photocatalysts can improve tooth color with or without light irradiation for 6 months after whitening. CLINICAL SIGNIFICANCE: In office whitening using 35% hydrogen peroxide without photocatalysts should be considered as a good treatment option for vital teeth whitening.

Ultrasonic measurement of dentin remineralization effects of dentifrices and silver diamine fluoride.

OBJECTIVE: This study investigated the dentin remineralization effect of the application of a functionalized tri-calcium phosphate (fTCP) dentifrice and a silver diamine fluoride (SDF) solution. MATERIAL AND METHODS: The materials used were: a fluoride-containing dentifrice with fTCP (fTCP＋), a fluoride-containing dentifrice without fTCP (fTCP-) and a 38% SDF solution. Following treatment, the dentin slabs were immersed in a 0.1-M lactic acid buffer solution and then placed in artificial saliva. This procedure was repeated three times daily for 28 days. The propagation time of longitudinal ultrasonic velocities (UV) and the Knoop hardness (KH) of the samples were measured. The samples were also observed using scanning electron microscopy. RESULTS: The SDF and fTCP＋ groups showed higher UV than the fTCP - group regardless of the application method. The F-SDF group at 28 days showed significantly higher UV (4121 ± 102 m/s) than the F-fTCP + group (3731 ± 65 m/s) (p < .05). The F-SDF group at 28 days showed significantly higher KH (47.4 ± 2.2) than the F-fTCP＋ group (43.3 ± 1.0) and the F-fTCP - group (42.9 ± 2.1) (p < .05). Closure of the dentinal tubules and crystal precipitation was detected on the surface of the fTCP＋ group to a greater extent than the fTCP - group. CONCLUSIONS: The fTCP-containing dentifrice and SDF solution effectively enhanced bovine dentin remineralization.

Evaluation of structural coloration of experimental flowable resin composites.

OBJECTIVE: To examine the effect of filler contentTo examine the effect of filler content on structural coloration of experimental flowable resin composites. OVERVIEW: Experimental composites containing spherical fillers and different filler contents (30, 40, 50, 60 and 70 wt%), a structural colored resin composite (Omnichroma), and a nanohybrid flowable resin composite (Gracefil LoFlo) were used. The optical characteristics of the specimens were measured on standard black and white backgrounds using a spectrophotometer under CIE D65 illuminant and the L*a*b* values were determined. The color matching abilities to artificial teeth were evaluated using the ΔE*ab and ΔE00 color difference formulas. One-way analysis of variance and Tukey's post hoc test were used. The spectral reflectance of experimental composites showed different trends in different backgrounds, plate thickness, and filler contents. In particular, higher spectral reflectance was observed on the white background at wavelengths ranging from 450 to 700 nm in both 1.5 and 3.0 mm plates when compared to the black background. The percent reflectivity tended to decrease with a decrease of the filler contents. The color matching abilities of the experimental composites improved with the increase in the filler contents. CONCLUSIONS: Structural coloration of the flowable resin composites were affected by the filler contents. CLINICAL SIGNIFICANCE: Clinical Significance: Higher filler contents might be needed to achieve the optimal color properties of structural colored flowable resin composites, thereby improving the restoration esthetics.

Clinical decision-making regarding endodontic therapy vs extraction and implant-assisted replacement: a systematic review and meta-analysis.

Clinical decision-making regarding retention and treatment vs extraction and replacement of teeth can be a significant challenge. This systematic review and meta-analysis aimed to assess decision-making in clinical practice related to the retention and endodontic treatment of natural dentition vs extraction and replacement with implant-assisted restorations. The PubMed/MEDLINE, Scopus, Web of Science, and Education Resources Information Center (ERIC) databases were comprehensively searched for studies published through May 31, 2019. All randomized controlled trials and cohort studies that assessed the effect of endodontic treatment/retreatment and implant treatment were included. Primary outcomes included success, survival, and failure rates. Meta-analysis software was used for data analysis. Of 1550 identified articles, 5 were eligible for qualitative and quantitative analyses. All 5 of the included studies reported that both therapies are viable and predictable treatment options. The meta-analysis showed no significant difference between therapies when survival rates were considered to be successes, while a significant difference was found in favor of endodontic therapy when survival rates were considered to be failures. The available evidence suggests that both therapies have approximately similar outcomes, but endodontic therapy provides moderately better outcomes. Endodontic therapy should be considered the first option when possible.

Intraoral Scanning with Rubber Dam Isolation in Place for Fabrication of a Chairside Computer-assisted Design and Computer-assisted Manufacture Ceramic Restoration.

AIM: The clinical report describes how chairside intraoral scanning can be performed while a rubber dam is in place prior to fabrication of a computer-assisted design and computer-assisted manufacture (CAD/CAM) ceramic restoration. BACKGROUND: Recently, combining a chairside CAD/CAM system with rubber dam isolation in place could be used in order to both speed up the restorative process and avoid any contamination to abutment surface, which are the positive effects to patients and clinicians. Unfortunately, manufacturers do not provide guidance on how to make use of chairside CAD/CAM restorations while rubber dam isolation is in place. CASE DESCRIPTION: The chief complaint of necessitating a crown after endodontic therapy and the patient was digital restorative procedure in single visit. Intraoral scanning with rubber dam isolation in place was planned and successfully completed in order to fabricate a chairside CAD/CAM ceramic crown. The software was able to interpose the scan of the prepped tooth with rubber dam isolation into a scan made without the rubber dam from which the tooth had been erased. CONCLUSION: Chairside CAD/CAM system can be used to scan, design, and fabricate crowns while rubber dam is kept intraorally. Initial scan without rubber dam is needed in order to interpose the second scan with rubber dam in place. CLINICAL SIGNIFICANCE: Combining the advantages of intraoral scanning and rubber dam isolation in place for the fabrication of a chairside CAD/CAM ceramic crown in a single visit is feasible.

Light Transmission for a Novel Chairside CAD/CAM Lithium Disilicate Ceramic.

AIM: To evaluate light transmission in a novel chairside CAD/CAM lithium disilicate ceramic with different thicknesses and with and without polishing. MATERIALS AND METHODS: Sixty flat samples (10 specimens/group) were fabricated from novel chairside CAD/CAM lithium disilicate ceramic blocks (Amber Mill, Hass Bio) with different thicknesses and with and without polishing as follows: (1) 1.0 mm thickness without polishing (1.0NoP); (2) 1.0 mm thickness with polishing (1.0Po); (3) 1.5 mm thickness without polishing (1.5NoP); (4) 1.5 mm thickness with polishing (1.5Po); (5) 2.0 mm thickness without polishing (2.0NoP); and (6) 2.0 mm thickness with polishing (2.0Po). Specimens were polished with a polishing system for lithium disilicate restorations following the manufacturer's recommendations. Light transmission was evaluated with a curing radiometer. Obtained data were subjected to two-way ANOVA followed by Tukey's post hoc tests (α = 0.05). SEM observations were conducted to evaluate surface microstructure. RESULTS: The light intensity through the lithium disilicate blocks with and without polishing was 200.9 mW/cm2 (16.1%) and 194.4 mW/cm2 (15.6%) for 1.0 mm specimens, 119.3 mW/cm2 (9.5%) and 111.9 mW/cm2 (9.0%) for 1.5 mm specimens, and 102.3 mW/cm2 (8.2%) and 96.0 mW/cm2 (7.7%) for 2.0 mm specimens. SEM images showed a smoother surface with polishing compared to nonpolished specimens. CONCLUSION: The thickness and polishing of the restorations were both significant influential factors in light transmission. CLINICAL SIGNIFICANCE: The range of light transmission percentage through the novel chairside CAD/CAM lithium disilicate blocks was 7.7-16.1%, suggesting that light attenuation through the material may influence the polymerization reaction of resin luting cement in the bonding process.

Influence of 38% silver diamine fluoride application on bond stability to enamel and dentin using universal adhesives in self-etch mode.

In order to evaluate the influence of 38% silver diamine fluoride (SDF) application on enamel and dentin bond stability of universal adhesives in self-etch mode, a 38% SDF and three universal adhesives were used in this study. Initial shear bond strength (ISBS), fatigue bond strength (FBS), and shear bond strength of survivors (SBSS) to enamel and dentin of universal adhesives in self-etch mode, with and without SDF application, were determined. SDF was applied to the polished enamel or dentin surface for 1 min, water-rinsed and air-dried for comparison with controls. The universal adhesives were applied to the prepared samples and composite resin was bonded using a mold-enclosed method. Enamel bond stability of universal adhesives with SDF (ISBS: 14.7-20.4 MPa; FBS: 5.5-7.4 MPa and SBSS: 14.4-21.5 MPa) was significantly weaker than those without SDF (ISBS: 28.0-29.2 MPa; FBS: 12.1-15.6 MPa and SBSS: 28.4-34.4 MPa). Dentin bond stability with SDF (ISBS: 14.8-20.9 MPa; FBS: 7.1-8.2 MPa and SBSS: 17.3-21.8 MPa) was also significantly weaker than without SDF (ISBS: 19.3-36.1 MPa; FBS: 11.0-13.7 MPa and SBSS: 22.2-34.6 MPa). The results suggest that SDF application on enamel and dentin reduces the bond stability of universal adhesives in self-etch mode.