Effect of Fluorohydroxyapatite on Biological and Physical Properties of MTA Angelus.

Objectives: This study aimed to assess the effect of addition of fluorohydroxyapatite (FHI) on biological and physical properties of mineral trioxide aggregate (MTA) Angelus. Materials and Methods: In this in vitro, experimental study, nano-FHI powder was first synthesized, and the morphology and chemical structure of particles were evaluated by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Three groups were evaluated in this study: MTA Angelus, MTA modified with 10% FHA, and MTA modified with 15% FHA. After mixing, the materials were applied to ring molds (10 mm diameter, 1 mm height), and the setting time of the three groups was evaluated according to ISO6876 and ASTMC266-03 with a Gillmore needle. The pH was measured using a pH meter at 24 and 48 hours and 7 days after mixing. The cytotoxicity of the materials was assessed in freshly mixed form and after 1 and 7 days using the methyl thiazolyl tetrazolium (MTT) assay according to ISO10993-5. Data were analyzed by one-way and repeated measures ANOVA and Tukey's test (alpha = 0.05). Results: The addition of FHA to MTA significantly decreased the initial setting time (P < 0.05) and had no significant effect on cell viability (compared with pure MTA Angelus) at 1 and 7 days. However, modified MTA groups in freshly mixed form showed significantly lower cell viability (P < 0.05). The pH remained alkaline at all time points. Conclusion: Addition of 15% FHA to MTA Angelus decreased its setting time with no adverse effect on cell viability (except for fresh form) or pH.

Evaluation of physical/mechanical properties of an experimental dental composite modified with a zirconium-based metal-organic framework (MOF) as an innovative dental filler.

OBJECTIVES: This study aimed to modify an experimental dental composite using a synthesized nano-structured methacrylated zirconium-based MOF to enhance physical/mechanical properties. METHODS: The previously known Uio-66-NH2 MOF was first synthesized and post-modified with Glycidyl Methacrylate (GMA). Fourier Transform Infrared (FTIR) Spectroscopy and CHNS analysis confirmed the post-modification reaction. The prepared filler was investigated by XRD, BET, SEM-EDS, and TEM. The experimental composite was prepared by mixing 60% wt. of resin matrix with 40% wt. of fillers, including silanized silica (SS) or Uio-66-NH-Me (UM). The experimental composites' depth of cure (DPC) was investigated in five groups (G1 =40% SS, G2 =30%SS+10%UM, G3 =20%SS+20%UM, G4 =10%SS+30%UM, G5 =40%UM). Then flexural strength(FS), Elastic Modulus(EM), solubility(S), water sorption(WS), degree of conversion(DC), polymerization shrinkage(PS), and polymerization stress(PSR) of the groups with DPC of more than 1 mm were investigated. Finally, the cytotoxicity of composites was studied. RESULTS: The groups with more than 20% wt. UM, filler (G4, G5) had lesser than 1 mm DPC. Therefore, we investigated three groups' physical and mechanical properties with lower than 20% UM filler (G1-G3). Within these groups, G3 has a higher FS, EM (P < 0.05), and lower WS and S (P < 0.05). DC dropped in G2 and G3 compared to G1 (p < 0.05), but there was no significant difference between G2 and G3 (P = 0.594). SIGNIFICANCE: This new filler is an innovative coupling-agent free filler and can be part of dental filler technology itself. It can also introduce a new group of dental fillers based on MOFs, but it still needs a complete investigation to be widely used.

Repairability of aged dimethacrylate-free ORMOCER-based dental composite resins with different surface roughening methods and intermediate materials.

STATEMENT OF PROBLEM: The repair of damaged composite resin restorations has been recommended as a conservative treatment option. However, a reliable protocol for repairing ORMOCER-based restorations is lacking. PURPOSE: The purpose of this in vitro study was to investigate the effect of different surface roughening methods, repair composite resins, and intermediate materials on the repair bond strength of a dimethacrylate-free ORMOCER-based composite resin. MATERIAL AND METHODS: Cylindrical composite resin specimens (Admira Fusion) were roughened by using hydrofluoric acid (HF) or a diamond rotary instrument. In both groups, 4 types of intermediate materials were used (Monobond-S, Clearfil SE bond [second bottle], Clearfil Universal bond, GC Composite Primer), and then half of the specimens were repaired with a similar composite resin, and the other half with dimethacrylate composite resin (Clearfil-APX). The specimens (n=20) were then subjected to repair bond strength and failure mode evaluation. The data were analyzed by using the Weibull test, 3-way and 1-way ANOVA, and the Tukey honestly significant difference (HSD) test (α=.05). RESULTS: All variables, including the surface roughening method, intermediate material, and repair composite resin, had a significant effect on repair bond strength (P<.001). The lowest repair bond strength values were obtained in the group roughened with HF, prepared with Monobond-S, and repaired with Admira Fusion, and the highest values were obtained in the group roughened with a rotary instrument, prepared with GC Composite Primer, and repaired with Clearfil APX (P<.05). All experimental groups had a lower bond strength than the cohesive and control groups (P<.05). In all experimental groups, the predominant failure modes were adhesive and mixed. CONCLUSIONS: The use of a diamond rotary instrument was a more reliable method of creating roughness, and different intermediate materials based on the clinical situation can be used to repair dimethacrylate-free ORMOCER-based composite resin with similar or different composite resins. However, in general, the highest repair bond strengths were achieved with Clearfil APX-repaired specimens.

A modified TEGDMA-based resin infiltrant using polyurethane acrylate oligomer and remineralising nano-fillers with improved physical properties and remineralisation potential.

OBJECTIVES: This study aimed to modify an experimental triethylene glycol dimethacrylate (TEGDMA) based resin infiltrant using PUA oligomer and two remineralising fillers, including fluorohydroxyapatite (FHA) and fluoride-doped bioactive glass (FD-BG), to improve the mechanical and physical properties and induce remineralising potential. MATERIALS AND METHODS: The polyurethane acrylate oligomer (PUA) was synthesised and characterised. Experimental resin infiltrant was prepared by mixing 10% of synthesised PUA with 88% TEGDMA. Water contact angle, penetration coefficient, and penetration depth were then measured. The FHA and FD-BG fillers were synthesised and characterised. To prepare nano-filled resin infiltrant, 5% of each powder was mixed with the prepared resin infiltrant. The prepared resin infiltrants were characterised to evaluate their degree of conversion, mechanical properties, water sorption, and solubility. The ion release of filled resin was also assessed. The non-infiltrated and infiltrated enamel specimens underwent fourteen days of pH-cycling, and a surface microhardness was done to assess the resistance to demineralisation. RESULTS: The results showed that the addition of PUA to TEGDMA increased the mechanical properties and decreased water sorption and solubility. The addition of synthesised FD-BG fillers to resin infiltrant significantly improved the resistance to demineralisation of enamel samples compared with other groups (p ≤ 0.001). The FHA fillers also improved the resistance to demineralisation; however, the produced changes were not statistically meaningful (p > 0.05). CONCLUSIONS: Based on the results, the PUA+TEGDMA+ FD-BG/FHA composite can be used as an alternative material for pure TEGDMA in enamel infiltration approaches owing to its better mechanical properties, lower water sorption and solubility, and also remineralisation potential. CLINICAL SIGNIFICANCE: A resin infiltrant with remineralisation potential, lower water sorption and solubility and higher mechanical properties may enhance the management of early caries lesions.

Effect of Cold Atmospheric Pressure Plasma Coupled with Resin-Containing and Xylitol-Containing Fluoride Varnishes on Enamel Erosion.

PURPOSE: Considering the suggested advantages of cold atmospheric plasma (CAP) in increasing the fluoride uptake by the enamel, this study aimed to assess enamel erosion following the application of helium CAP and two types of fluoride varnishes. METHODS: The microhardness of 70 bovine enamel specimens was measured using a Vickers hardness tester. The specimens were randomly divided into 7 groups (n = 10): control, CAP (P), resin-containing fluoride varnish (RF), CAP + resin-containing fluoride varnish (PRF), fluoride varnish (F), CAP + fluoride varnish (PF), and erosion (E). The specimens in the control and erosion groups did not receive CAP or fluoride varnish. All specimens underwent erosive challenge 4 times/day using hydrochloric acid and artificial saliva except for the control specimens that remained in distilled water during the course of the study. After 5 days of erosive challenge, microhardness was measured again, and the percentage of microhardness change was calculated. Surface roughness of two specimens in each group was assessed by atomic force microscopy (AFM). Data were analyzed using one-way ANOVA followed by Tamhane's post-hoc test. RESULTS: The percentage of microhardness change in all groups was significantly higher than that of the control group. All groups showed significantly lower percentage of microhardness change compared with the E group except for the P group; no significant difference was noted in microhardness change of P and E groups. Other experimental groups had no significant difference with each other. Surface roughness was the highest in PRF and the lowest in the F group. CONCLUSION: CAP application had no significant effect on increasing the enamel resistance to erosion. However, enamel resistance to erosion increased significantly after fluoride varnish application alone or fluoride varnish application combined with CAP. No significant difference was noted between the two types of varnishes in this regard. CAP increased the surface roughness while fluoride varnish application alone decreased the roughness.

Resistance to demineralisation of adjacent enamel and dentine, fluoride release and dentine bond strength of fluoride-containing self-etch adhesive systems.

BACKGROUND: The current study aimed to assess the amount of fluoride released from fluoride-containing dental adhesives and its effect on micro-tensile bond strength (µTBS) and on resistance to demineralisation of dentine and enamel. MATERIAL AND METHODS: Two fluoride-containing dental adhesives, and a fluoride-free adhesive were used as experimental adhesives. After thermal cycling the µ-TBS of adhesives to dentine and the failure mode were assessed. The fluoride release and cross-sectional microhardness (CSMH) of specimens were measured before and after one day, 7 and 28 days of pH-cycling. The data were analysed using one-way ANOVA, Weibull statistics and repeated measures ANOVA. RESULTS: The results indicated a significant difference between the group of FL and both the SE and LBF groups (p≤0.001). The CSMH values of both the dentine and enamel underneath the adhesives was reduced at 28 th day of the pH-cycling compared to the baseline (p≤0.001). From day 1 to day 28, the released fluoride declined in both the fluoride containing dental adhesives (p≤0.001). CONCLUSIONS: Based on the results, the released fluoride from dental adhesives may adversely influence the bond strength and durability of the resin/dentine interface. Moreover, the released fluoride didn't improve the resistance to demineralisation of adjacent enamel and dentine to bond interface. Key words:Fluoride release, micro-tensile bond strength, microhardness, fluoride-containing adhesives.

In-vitro bioactivity evaluation and physical properties of an epoxy-based dental sealer reinforced with synthesized fluorine-substituted hydroxyapatite, hydroxyapatite and bioactive glass nanofillers.

The purpose of this study was to evaluate the physical properties and bioactivity potential of epoxy-based dental sealers modified with synthesized bioactive glass (BAG), hydroxyapatite (HA) and fluorine substituted hydroxyapatite (FHA) nanoparticles. The synthesized powders were incorporated at 10% and 20% into the epoxy-based dental sealer. The setting time, flow and solubility and microhardness of the modified and unmodified samples were examined. The bioactivity was evaluated using FESEM-EDX and elemental mapping, ATR-FTIR and XRD. The flow value of all of the experimental groups except the FHA modified samples, was greater than 20 mm. Concerning solubility, no specimens exhibited more than 1% weight loss. The solubility value of the FHA groups was statistically significant lower than other groups (p ≤ 0.001). The mean hardness values of all of the modified samples were significantly higher than the unmodified group (p ≤ 0.001). Regarding bioactivity, in vitro study revealed that after 3 days immersion in SBF a compact and continuous calcium phosphate layer formed on the surface of epoxy sealers containing BAG and HA nanoparticles. Based on these results, the addition of BAG and HA nanoparticles did not adversely alter the physical properties of epoxy sealers. Additionally, they improved the in vitro bioactivity of the epoxy sealer.

Comparative assessment of the crystalline structures of powder and bulk human dental enamel by X-ray diffraction analysis.

OBJECTIVES: The aim of this study was to assess and compare the crystalline structures of both powder and bulk human dental enamel by X-ray diffraction analysis (XRD). METHODS: The buccal surfaces of 60 selected noncarious third molars were divided into two groups of powdered and bulk enamel specimens. To prepare enamel powders, the enamel tissues were ground and powdered manually using a mortar and pestle. For bulk samples, the enamel slabs were sectioned using a low-speed diamond saw. The crystalline structures of samples were analyzed by XRD, and the obtained data were analyzed. The values of the lattice parameters were obtained using the equation of hexagonal crystalline structures. The crystal sizes and microstrains of crystallites were calculated using both the Scherrer and Williamson-Hall (W-H) methods. The total area under the peaks was considered as the criterion for assessing crystallinity. The data were analyzed by a parametric independent t-test and nonparametric Mann-Whitney test using SPSS for Windows at a significance level of 0.05. RESULTS: The results of the current study revealed significant differences between the crystallinity values and crystal sizes of the two study groups (p ≤ 0.001). The powdered samples showed higher crystallinity and smaller crystal sizes than those of the bulk samples. The obtained strain values of the powder samples were nearly twice those of the bulk samples. This difference was not statistically significant (p = 0.76). CONCLUSIONS: The results of this study revealed that the sample preparation method for human tooth enamel can affect the crystalline data obtained from XRD analysis.

Prevention of white spot lesions using three remineralizing agents: An in vitro comparative study.

Background . Enamel demineralization around orthodontic brackets is an important clinical problem. This study sought to compare the efficacy of sodium fluoride (NaF), casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACP-F; MI Paste Plus) and a water-based cream (Remin Pro), which contains hydroxyapatite and fluoride for prevention of enamel demineralization. Methods . Fifty-six sound human premolars extracted for orthodontic purposes were collected. After cleaning, the crowns were mounted in acrylic resin and all the surfaces were coated with nail varnish except for a 3×4-mm window on the buccal surface. The samples were randomly divided into four groups of 14 and subjected to pH cycling for 14 days, during which the teeth were immersed in artificial saliva for 21 hours and in demineralizing agent for three hours daily. Before transferring the samples from the saliva to the demineralizing solution, the remineralizing agent (0.05% NaF, MI Paste Plus or Remin Pro Paste, depending on the group) was applied on the samples once a day for five minutes. No remineralizing agent was used in the control group. Surface microhardness of samples was measured by Vickers microhardness tester at baseline and after the intervention. The data were analyzed using one-way ANOVA, ANCOVA, Bonferroni test and Tukey test. Statistical significance was set at P<0.05. Results . The mean microhardness was significantly different between the test and control groups (P<0.0001). Other differences were not significantly different (P>0.05). Conclusion . The results showed that 0.05% NaF was more efficient than Remin Pro and MI Paste Plus for prevention of white spot lesions (WSLs). Remin Pro and MI Paste Plus were not significantly difference from the control group in this regard.

Interfacial fracture toughness of self-adhesive and conventional flowable composites to dentin using different dentin pretreatments.

AIM: The aim of the present study was to investigate the effect of different dentin pretreatments on the interfacial fracture toughness of a self-adhesive flowable composite to dentin compared with that of a conventional flowable composite. METHODS: Caries-free human molars were sectioned to expose the underlying dentin and were randomly divided into seven groups (N = 12) of dentin pretreatments bonded to a self-adhesive flowable composite (Vetise Flow, VF) or a conventional flowable composite (Clearfil Magesty Flow, CM). For VF; Control group (group C-VF), there was no pretreatment, self-etching primer (SP), oxalate dentin desensitizer (OX), and chlorhexidine gluconate (CH) were used. For CM; SP (group SP-CM), OX followed by SP (OX-CM), and CH followed by SP (CH-CM) were used. The interfacial fracture toughness was measured using a universal testing machine. Data were analyzed by Kruskal-Wallis test and analysis of variance. RESULTS: For VF, the fracture toughness of SP-VF was significantly higher than that of other groups. For CM, a significantly higher fracture toughness for SP-CM than that of OX-CM was found. For all dentin pretreatments, the fracture toughness values were significantly higher for CM compared with the VF. CONCLUSIONS: The self-adhesive flowable composite had reduced bonding efficacy to dentin compared with that of the conventional flowable composite, regardless of the type of dentin pretreatment.

The effect of thermocycling on the degree of conversion and mechanical properties of a microhybrid dental resin composite.

OBJECTIVE: The purpose of this study was to investigate the degree of conversion (DC) and mechanical properties of a microhybrid Filtek Z250 (3M ESPE) resin composite after aging. METHOD: The specimens were fabricated using circular molds to investigate Vickers microhardness (Vickers hardness number [VHN]) and DC, and were prepared according to ISO 4049 for flexural strength testing. The initial DC (%) of discs was recorded using attenuated total reflectance-Fourier transforming infrared spectroscopy. The initial VHN of the specimens was measured using a microhardness tester under a load of 300 g for 15 seconds and the flexural strength test was carried out with a universal testing machine (crosshead speed, 0.5 mm/min). The specimens were then subjected to thermocycling in 5°C and 55°C water baths. Properties were assessed after 1,000-10,000 cycles of thermocycling. The surfaces were evaluated using scanning electron microscopy (SEM). Data were analyzed using 1-way analysis of variance followed by the Tukey honest significant difference post hoc test. RESULTS: Statistical analysis showed that DC tended to increase up to 4,000 cycles, with no significant changes. VHN and flexural strength values significantly decreased upon thermal cycling when compared to baseline (p < 0.05). However, there was no significant difference between initial and post-thermocycling VHN results at 1,000 cycles. SEM images after aging showed deteriorative changes in the resin composite surfaces. CONCLUSIONS: The Z250 microhybrid resin composite showed reduced surface microhardness and flexural strength and increased DC after thermocycling.

Effects of incorporation of 2.5 and 5 wt% TiO2 nanotubes on fracture toughness, flexural strength, and microhardness of denture base poly methyl methacrylate (PMMA).

PURPOSE: The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO2) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS: TiO2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO2:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS: SEM images of n-TiO2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO2 represented the anatase crystal phase of TiO2. Moderate to very strong significant positive correlations were observed between the concentration of n-TiO2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO2 were significantly higher than those of control (P≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO2 (but not those of 2.5% n-TiO2) was higher than control (P=.002). CONCLUSION: Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

Bond strength of self-adhesive resin cement to base metal alloys having different surface treatments.

BACKGROUND: This study aimed to assess and compare the shear bond strength of self-etch and self-adhesive resin cement to nickel-chromium-cobalt alloy with different surface treatments. MATERIALS AND METHODS: In this in vitro study, a total of 120 disks were fabricated of VeraBond II base metal alloy. Specimens were divided into 15 groups of 8 based on the type of cement and surface treatment. The five surface treatments studied included sandblasting alone, application of Alloy Primer with and without sandblasting, and application of Metal Primer II with and without sandblasting. The three cement tested included Panavia F2.0, RelyX Unicem (RU), and G-Cem (GC). After receiving the respective surface treatments, the specimens were thermocycled for 1500 cycles and underwent shear bond strength testing. Data were analyzed using SPSS 20.0 and three-way analysis of variance. P values of the significant level of 0.05 were reported. RESULTS: The results exhibited that the mean bond strengths in sandblasted groups were higher than nonsandblasted one. These differences were significantly higher in the sandblasted groups of Panavia F2.0 and RU cement (P < 0.05). The mean bond strength values between GC and Panavia F2.0 were not statistically significant (P > 0.05). The highest bond strength was recorded for Panavia F2.0 with the surface treatment of both sandblasting and Metal Primer II. CONCLUSION: Based on the results, sandblasting improves the shear bond strength of self-etch and self-adhesive resin cement to base metal alloys. The best results can be achieved with a combination of sandblasting and metal primers. The performance of resin cement depends on to their chemical composition, not to the type of system.

Evaluation of Antimicrobial Properties of Conventional Poly(Methyl Methacrylate) Denture Base Resin Materials Containing Hydrothermally Synthesised Anatase TiO2 Nanotubes against Cariogenic Bacteria and Candida albicans.

The purpose of this study was to investigate the antimicrobial properties of a conventional poly methyl methacrylate (PMMA) modified with hydrothermally synthesised titanium dioxide nanotubes (TNTs). Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimum fungicidal concentrations (MFC) for planktonic cells of the TiO2 nanotubes solution against Lactobacillus acidophilus, Streptococcus mutans and Candida albicans were determined. The powder of conventional acrylic resin was modified using 2.5% and 5% by weight synthesised titanium dioxide (TiO2) nanotubes, and rectangular-shaped specimens (10 mm × 10 mm × 3 mm) were fabricated. The antimicrobial properties of ultraviolet (UV) and non-UV irradiated modified, and non-modified acrylic resins were evaluated using the estimation of planktonic cell count and biofilm formation of the three microorganisms mentioned above. The data were analysed by one-way analysis of variance (ANOVA), followed by a post-hoc Tukey's test at a significance level of 5%. MIC, for Streptococcus. mutans, Lactobacillus. acidophilus, and Candida. albicans, MBC for S. mutans and L. acidophilus and MFC for Candida. albicans were obtained more than 2100 µg/mL. The results of this study indicated a significant reduction in both planktonic cell count and biofilm formation of modified UV-activated acrylic specimens compared with the control group (p = 0.00). According to the results of the current study, it can be concluded that PMMA/TiO2 nanotube composite can be considered as a promising new material for antimicrobial approaches.

Evaluation of Polymerization Efficacy in Composite Resins via FT-IR Spectroscopy and Vickers Microhardness Test.

Background and aims. Polymerization efficacy affects the properties and performance of composite resin restorations.The purpose of this study was to evaluate the effectiveness of polymerization of two micro-hybrid, two nano-hybrid and one nano-filled ormocer-based composite resins, cured by two different light-curing systems, using Fourier transformation infrared (FT-IR) spectroscopy and Vickers microhardness testing at two different depths (top surface, 2 mm). Materials and methods. For FT-IR spectrometry, five cylindrical specimens (5mm in diameter × 2 mm in length) were prepared from each composite resin using Teflon molds and polymerized for 20 seconds. Then, 70-µm wafers were sectioned at the top surface and at2mm from the top surface. The degree of conversion for each sample was calculated using FT-IR spectroscopy. For Vickers micro-hardness testing, three cylindrical specimens were prepared from each composite resin and polymerized for 20 seconds. The Vickers microhardness test (Shimadzu, Type M, Japan) was performed at the top and bottom (depth=2 mm) surfaces of each specimen. Three-way ANOVA with independent variables and Tukey tests were performed at 95% significance level. Results. No significant differences were detected in degree of conversion and microhardness between LED and QTH light-curing units except for the ormocer-based specimen, CeramX, which exhibited significantly higher DC by LED. All the composite resins showed a significantly higher degree of conversion at the surface. Microhardness was not significantly affected by depth, except for Herculite XRV Ultra and CeramX, which showed higher values at the surface. Conclusion. Composite resins containing nano-particles generally exhibited more variations in degree of conversion and microhardness.

Interfacial fracture toughness of different resin cements bonded to a lithium disilicate glass ceramic.

OBJECTIVES: To evaluate the effect of HF acid etching and silane treatment on the interfacial fracture toughness of a self-adhesive and two conventional resin-based cements bonded to a lithium disilicate glass ceramic. METHODS: Lithium disilicate glass ceramic discs were prepared with two different surface preparations consisting of gritblasted with aluminium oxide, and gritblasted and etched with hydrofluoric acid. Ceramic surfaces with a chevron shaped circular hole were treated by an optimized silane treatment followed by an unfilled resin and then three different resin cements (Variolink II, Panavia F2, and Multilink Sprint). Specimens were kept in distilled water at 37°C for 24h and then subjected to thermocycling. The interfacial fracture toughness was measured and mode of failures was also examined. Data were analysed using analysis of variance followed by T-test analysis. RESULTS: No statistically significant difference in the mean fracture toughness values between the gritblasted and gritblasted and etched surfaces for Variolink II resin cement was found (P>0.05). For the gritblasted ceramic surfaces, no significant difference in the mean fracture toughness values between Panavia F2 and Variolink II was observed (P>0.05). For the gritblasted and etched ceramic surfaces, a significantly higher fracture toughness for Panavia F2 than the other cements was found (P<0.05). CONCLUSIONS: The interfacial fracture toughness for the lithium disilicate glass ceramic system was affected by the surface treatment and the type of luting agent. Dual-cured resin cements demonstrated a better bonding efficacy to the lithium disilicate glass ceramic compared to the self-adhesive resin cement. CLINICAL SIGNIFICANCE: The lithium disilicate glass ceramic surfaces should be gritblasted and etched to get the best bond when used with Panavia F2 and Multilink Sprint resin cements, whereas for the Variolink II only gritblasting is required. The best bond overall is achieved with Panavia F2.