Dentin disinfection and adhesive bond strength using modified photoactivated carbon nanoparticles.

AIMS: The present study aimed to investigate the bond integrity and disinfection efficacy of Methylene blue(MB) alone, MB-PDT (Photodynamic therapy), MB@ carbon nanoparticles (CP)-PDT, and Cr, Cr: YSGG (ECL) against lactobacilli in Caries-affected dentin (CAD) MATERIAL AND METHODS: Methods consisted of Shear bond strength (SBS), Scanning electron microscopy (SEM), energy dispersive X-ray (EDX), methods of disinfection, and failure analysis. CAD samples were prepared and biofilm formed on the specimens randomly allocated into five groups based on disinfection. Group 1: CHX; Group 2: MB; Group 3: MB-PDT: group 4: MB@CP-PDT and group 5: ECL. After disinfection Colony forming units were measured and specimens were restored and positioned under a universal testing machine (UTM). Failure analysis was performed using a stereomicroscope. The difference in survival rate was assessed using the Kruskal-Walis test. Mean and standard deviation for bond values after different methods of disinfection was evaluated using analysis of variance (ANOVA) and Post Hoc Tukey. The significance level was p<0.05 RESULTS: Morphological analysis revealed that CPs under SEM are flat discs with edged irregular shapes. EDX analyses show a spike indicating carbon particles by more than 95%. MB@CP-PDT displayed the highest reduction in lactobacillus levels in comparison to the other disinfection methods. The highest SBS was exhibited by the CAD sample disinfected with ECL. The lowest SBS values in CAD specimens after cavity cleansing with MB alone. The predominant failure type in CAD disinfected with MB alone, ECL CHX, MB-PDT, and MB@CP-PDT was adhesive. CONCLUSION: The use of MB@CP-PDT showed high antibacterial potency against lactobacillus but demonstrated bond values similar to CHX. Use of Er, Cr: YSGG showed considerable effectiveness against lactobacillus along with the highest bond values.

The Effect of Dentifrice on Micro-Hardness, Surface Gloss, and Micro-Roughness of Nano Filled Conventional and Bulk-Fill Polymer Composite-A Micro Indentation and Profilometric Study.

The aim of the present study was to evaluate the effect of brushing with two whitening dentifrices (Colgate Optic White (COW) and Colgate Optic White Charcoal (COC)) on surface gloss, micro-roughness, and micro-hardness of nanostructured hybrid conventional (Z350) and bulk-fill (Tetric N Ceram bulk-fill) polymer composite. In total, 96 disk samples using two nano-hybrid composite polymers (Z350 and Tetric N Ceram Bulk-fill) were prepared. All specimens were exposed to two different dentifrices (COW and COC), resulting in four main subgroups in the study. Specimens were assessed for surface gloss, micro-roughness (Ra), and micro-hardness using standardized methodology. Means and standard deviations of properties compared using paired t-test, one-way and two-way ANOVA, and post hoc test. The presence of dentifrices did not show any significant difference in micro-hardness values of Z350 (p > 0.05), whereas micro-hardness of bulk-fill composite significantly reduced on dentifrices exposure (p ≤ 0.05). Bulk-fill polymer composite showed significant reduction in gloss after dentifrice exposure (p < 0.05), however, Z350 showed no significant loss of gloss due to dentifrices (p > 0.05). A significant increase in Ra was observed for both resin materials after exposure to dentifrices (COC and COW). Conventional resin composite (Z350) showed comparable surface hardness and gloss before and after dentifrice exposure, however, micro-roughness increased significantly due to dentifrice exposure. Bulk-fill resin (Tetric N Ceram) showed significant loss of micro-hardness and gloss and increase in micro-roughness on dentifrice exposure. Conventional nano-hybrid composite polymer showed better durability in resisting loss of surface properties compared to bulk-fill resin polymer in the present experiment.

Influence of Concentration Levels of ß-Tricalcium Phosphate on the Physical Properties of a Dental Adhesive.

Our study assessed the influence of integrating 5% and 10% tricalcium phosphate (ß-TCP-Ca3(PO4)2.) nanoparticles into a dental adhesive on the adhesive's bonding. To evaluate the filler nanoparticles, scanning electron microscopy (SEM), Energy Dispersive X-Ray (EDX) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and micro-Raman spectroscopy techniques were used. Shear Bond strength (SBS) testing, degree of conversion (DC) analysis, investigation of the adhesive-dentin interface, and biofilm experiments were conducted. The SEM micrographs revealed non-uniform agglomerates, while the EDX demonstrated the existence of oxygen 'O' (24.2%), phosphorus 'P' (17.4%) and calcium 'Ca' (60.1%) in the ß-TCP nanoparticles. The FTIR and micro-Raman spectra indicated characteristic bands for ß-TCP containing materials. The 10 wt.% ß-TCP adhesive presented the highest SBS values (NTC-10 wt.% ß-TCP: 33.55 ± 3.73 MPa, TC-10 wt.% ß-TCP: 30.50 ± 3.25 MPa), followed by the 5 wt.% ß-TCP adhesive (NTC-5 wt.% ß-TCP: 32.37 ± 3.10 MPa, TC-5 wt.% ß-TCP: 27.75 ± 3.15 MPa). Most of the detected failures after bond strength testing were adhesive in nature. The ß-TCP adhesives demonstrated suitable dentin interaction by forming a hybrid layer (with few or no gaps) and resin tags. The ß-TCP adhesives (10 wt.%) revealed lower DC values compared to control. The incorporation of 5 and 10 wt.% concentrations of ß-TCP particles resulted in an increase in SBS values. A linear decline in DC values was witnessed when the nanoparticle concentration was increased. Further research focusing on exploring the influence of higher filler concentrations on adhesive's properties is recommended.

Influence of Conventional Polymer, Hybrid Polymer and Zinc Phosphate Luting Agents on the Bond Strength of Customized Zirconia Post in Premolars-An In-Vitro Evaluation.

The aim was to identify the influence of conventional polymeric resin based cement (RC), hybrid polymer modified glass ionomer (RMGIC) and Zinc phosphate cement (ZPC) on the pull out strength of the customized zirconia post in premolars. Access cavity and root canals were performed in sixty premolar teeth with the standardized crown down technique (ProTaper Universal, Dentsply). Post space impressions were scanned, and the pre-sintered Zenostar Zr Translucent blanks (Weiland Dental, Pforzheim) were milled with the Opera-system to form the post. All prepared specimens were divided equally in three groups based on the cement type employed for luting as follows: group A: ZPC; group B (GC Fuji PLUS Capsule): RMGIC; group C (and RC (3M RelyX ARC). Ten specimens in each group were thermocycled (TC) at 5 and 55 °C in distilled water baths (40,000 cycles). Pull out bond strength was assessed using a universal testing machine at 0.5 mm/min. The means and standard deviations were compared using ANOVA and Tukey Kramer multiple comparisons tests. A significant difference among the cement groups as well as between TC and non-thermocycled (NTC) groups (p < 0.05) was observed. The highest tensile stress was demonstrated among group C (Resin, 69.89 ± 4.81 (NTC), 64.06 ± 4.36 (TC)) with the least in group A, (zinc phosphate, 43.66 ± 5.02 (NTC), 37.70 ± 5.10 (TC)) for both groups. Group A presented with 100% adhesive bond failures, followed by 80% in group C and 70% in group B, respectively. A similar outcome was observed in the TC group for the cement; however, unlike the NTC group, the TC group showed more cohesive failures compared to the NTC mixed failure. Dual cure polymer based cement demonstrated higher bond strength and efficient adhesive bonding of the customized Zr post with root dentine compared to zinc phosphate (non-polymeric) and RMGIC (hybrid polymer). Thermocycling compromised Zr post adhesive bonding to root dentin.

Shear bond characteristics and surface roughness of poly-ether-ether-ketone treated with contemporary surface treatment regimes bonded to composite resin.

AIM: To evaluate and compare the influence of contemporary surface treatments of air abrasions, sulfuric acid, and Photodynamic therapy (PDT) on the adhesive bonding and surface roughness of Poly-ether-ether-ketone (PEEK) bonded to resin composite. MATERIAL AND METHODS: One hundred and fifty PEEK (disk-shaped) specimens of 10 mm diameter and 2 mm thickness were prepared. Specimens were subjected to the following surface treatments, Control (no treatment), PDT, air abrasion using Alumina particles (110 µm) (AA-AP), Sulfuric acid (SA), and air abrasion using diamond particles (10-20 µm) AA-DP. Surface roughness (Ra) of treated samples were evaluated using surface profilometer. Universal testing machine was used to evaluate shear bond strength after composite resin build-up. Stereomicroscope was utilized for failure analysis of de-bonded samples of all five groups. Statistical analysis was performed utilizing one-way analysis of variance (ANOVA) to measure means and standard deviations of SBS among studied groups and the means of SBS were paralleled by Tukey multiple comparison tests (p > 0.05). RESULTS: The highest SBS was observed by 98% SA (19.25 ± 0.68 MPa). While specimen treated with PDT (11.69 ± 0.12 MPa) showed the lowest SBS. PEEK surface, treated with PDT and AA-DP demonstrated comparable SBS (p > 0.05). PEEK when pretreated with 98% SA (2.658 ± 0.658 µm) exhibited a significantly higher Ra value as compared to other surface-treated groups (p < 0.05). CONCLUSION: PEEK surface treated with SA showed the highest SBS and surface roughness compared to other groups. Surface roughness of PEEK treated with PDT, AA-AP, and AA-DP demonstrated no difference in Ra. PEEK surface treatment technique should be further investigated to develop reliable adhesive resin bonding.

Modified photoactivated methylene blue-incorporated quartz particles for dentin disinfection: A scanning electron microscope and spectroscopic analysis.

The aim of this study was to synthesize methylene blue-incorporated quartz particles (MB@QP) and to investigate its anti-bactericidal properties. Methylene blue was incorporated inside QP and characterized for morphology and chemical structure using scanning electron microscope (SEM) and Fourier transformed infrared spectroscopy (FTIR). Specimens were randomly divided into experimental and control groups (n = 9/groups). The dentin specimen infected with Enterococcus faecalis was treated using different treatment modalities: Control groups: treatment with 5.25% of sodium hypochlorite (NaOCl) for 60 s; MB: treatment with 1 ml MB solution and incubated for 60 s; MB-PDT (photodynamic therapy): treatment with 1 ml MB solution followed by irradiation using diode laser for 60 s; MB-QP-PDT: specimens treated with MB@QP and irradiated by the diode laser for 60s, and Er,Cr:YSGG laser alone. MB@PDT therapy showed the highest efficacy in reducing the survival rate of E. faecalis (0.49%) in comparison to control NaOCl (0.78%) and Er,Cr:YSGG laser treatment (2.17%). Encapsulating MB into QP followed by the PDT significantly improved the bactericidal capacity and significantly reduced the bacterial survival rate to 0.11% (p < .05) compared to other groups. The combination of MB incorporated into QP and PDT could be an alternative treatment modality to conventional disinfection method for eliminating bacteria from the tooth dentin. RESEARCH HIGHLIGHTS: Quartz particles are potent in delivering the photosensitizer. Photoactivated MB@QP has a higher efficacy in eliminating bacteria from tooth dentin.

Surface Properties of Polymer Resins Fabricated with Subtractive and Additive Manufacturing Techniques.

This study aimed to compare the surface roughness, hardness, and flexure strength of interim indirect resin restorations fabricated with CAD-CAM (CC), 3D printing (3D), and conventional techniques (CV). Twenty disk (3 mm × Ø10 mm) and ten bar specimens (25 × 2 × 2 mm) were fabricated for the CC, 3D, and CV groups, to be used for surface roughness, micro-hardness, and flexural strength testing using standardized protocol. Three indentations for Vickers micro-hardness (VHN) were performed on each disk and an average was identified for each specimen. Surface micro-roughness (Ra) was calculated in micrometers (µm) using a 3D optical non-contact surface microscope. A three-point bending test with a universal testing machine was utilized for assessing flexural strength. The load was applied at a crosshead speed of 3 mm/min over a distance of 25 mm until fracture. Means and standard deviations were compared using ANOVA and post hoc Tukey-Kramer tests, and a p-value of ≤0.05 was considered statistically significant. Ra was significantly different among the study groups (p < 0.05). Surface roughness among the CC and CV groups was statistically comparable (p > 0.05). However, 3D showed significantly higher Ra compared to CC and CV samples (p < 0.05). Micro-hardness was significantly higher in 3D samples (p < 0.05) compared to CC and CV specimens. In addition, CC and CV showed comparable micro-hardness (p > 0.05). A significant difference in flexural strength was observed among the study groups (p < 0.05). CC and 3D showed comparable strength outcomes (p > 0.05), although CV specimens showed significantly lower (p < 0.05) strength compared to CC and 3D samples. The 3D-printed provisional restorative resins showed flexural strength and micro-hardness comparable to CAD-CAM fabricated specimens, and surface micro-roughness for printed specimens was considerably higher compared to CAD-CAM and conventional fabrication techniques.

Polymer-Based Bioactive Luting Agents for Cementation of All-Ceramic Crowns: An SEM, EDX, Microleakage, Fracture Strength, and Color Stability Study.

The aim of the study was to compare microleakage and fracture loads of all ceramic crowns luted with conventional polymer resins and polymeric bioactive cements and to assess the color stability of polymeric bioactive cements. Seventy-five extracted premolar teeth were tested for fracture loads and microleakage in all-ceramic crowns cemented with two types of polymeric bioactive cements and resin cements. In addition, the degree of color change for each cement with coffee was assessed. Thirty maxillary premolar teeth for fracture loads and thirty mandibular premolar teeth for microleakage were prepared; standardized teeth preparations were performed by a single experienced operator. All prepared specimens were randomly distributed to three groups (n = 20) based on the type of cement, Group 1: resin cement (Multilink N); Group 2: polymeric bioactive cement (ACTIVA); Group 3: polymeric bioactive cement (Ceramir). The cementation procedures for all cements (Multilink, ACTIVA, and Ceramir) were performed according to the manufacturers' instructions. All specimens were aged using thermocycling for 30,000 cycles (5-55 °C, dwell time 30 s). These specimens were tested using the universal testing machine for fracture strength and with a micro-CT for microleakage. For the color stability evaluation, the cement specimens were immersed in coffee and evaluated with a spectrometer. Results: The highest and lowest means for fracture loads were observed in resin cements (49.5 ± 8.85) and Ceramir (39.8 ± 9.16), respectively. Ceramir (2.563 ± 0.71) showed the highest microleakage compared to resin (0.70 ± 0.75) and ACTIVA (0.61 ± 0.56). ACTIVA cements showed comparable fracture loads, microleakage, and stain resistance compared to resin cements.

Enamel Remineralization Competence of a Novel Fluoride-Incorporated Bioactive Glass Toothpaste-A Surface Micro-Hardness, Profilometric, and Micro-Computed Tomographic Analysis.

This study aimed to analyze the enamel remineralization efficacy of a novel fluoridated bioactive glass (F-BG) toothpaste compared to a standard fluoride toothpaste. Seventy-two enamel blocks (N = 72) were divided into groups of twenty-four blocks according to the toothpaste exposure-group 1: brushed with distilled water, group 2: brushed with fluoride toothpaste (ColgateTM), and group 3: brushed with F-BG toothpaste (BioMinFTM). Pre-brushing, enamel blocks were demineralized using 6 wt.% citric acid (pH = 2.4). Tooth brushing was performed using a mixture of respective toothpaste and artificial saliva (AS), and each enamel block received 5000 linear strokes. The samples were assessed for surface micro-hardness (to estimate Vickers hardness number, VHN), surface roughness (Ra), and volume loss/gain using micro-computed tomography (micro-CT). The highest increase in the VHN was noticed for group 3 (117.81) followed by group 2 (61.13), and all the intragroup comparisons were statistically significant (p < 0.05). Demineralization increased the Ra values, and a decrease was observed post-remineralization for all the groups. The maximum Ra decrease was observed for group 3 (-223.2 nm) followed by group 2 (-55.6 nm), and all the intragroup comparisons were again statistically significant (p < 0.05). Micro-CT investigation revealed that the enamel volume decreased after demineralization and increased after remineralization among all groups. The F-BG toothpaste showed greater enamel surface micro-hardness (increased VHN), smoother surface (low roughness), and better volume restoration (remineralization) in comparison to the fluoride toothpaste.

Influence of TiO2 and ZrO2 Nanoparticles on Adhesive Bond Strength and Viscosity of Dentin Polymer: A Physical and Chemical Evaluation.

The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO2) or zirconium oxide (ZrO2) to yield 5% TiO2 and 5% ZrO2 adhesives, respectively, and then analyze the impact of this reinforcement on various mechanical properties of the adhesives. The EA contained a blend of monomers such as bisphenol A glycol dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA), and ethyl 4-dimethylamino benzoate and camphorquinone. The EA included ethyl 4-dimethylamino benzoate and camphorquinone photo-initiators, and diphenyliodonium hexafluorophosphate (DPIHP) was also included to act as an electron initiator. The TiO2 and ZrO2 nanoparticles were incorporated into the EA post-synthesis. To characterize the filler nanoparticles, scanning electron microscopy (SEM) and line-energy dispersive X-ray (EDX) spectroscopy were performed. The adhesives were characterized by analyzing their rheological properties, shear-bond strength (SBS), and interfacial failure types. Further, the resin-dentin interface was also analyzed via SEM. The TiO2 nanoparticles were spherically shaped on the SEM micrographs, while the ZrO2 nanoparticles were seen as non-uniformly shaped agglomerates. The EDX mapping demonstrated the presence of Ti and oxygen for TiO2 and Zr and oxygen for the ZrO2 nanoparticles. Both 5% TiO2 and 5% ZrO2 adhesives revealed decreased viscosity as compared with the EA. The 5% TiO2 adhesive demonstrated higher SBS values for both non-thermocycled (NTC) and thermocycled samples (NTC: 25.35 ± 1.53, TC: 23.89 ± 1.95 MPa), followed by the 5% ZrO2 adhesive group (NTC: 23.10 ± 2.22, TC: 20.72 ± 1.32 MPa). The bulk of the failures (>70%) were of adhesive type in all groups. The SEM analysis of the resin-dentin interface revealed the development of a hybrid layer and resin tags (of variable depth) for the EA and 5% TiO2 groups. However, for the 5% ZrO2 group, the hybrid layer and resin tag establishment appeared compromised. Reinforcement of the EA with TiO2 or ZrO2 caused an increase in the adhesive's SBS (with the 5% TiO2 group demonstrating the highest values) in comparison with the EA (without nanoparticles). However, both nanoparticle-containing adhesives revealed decreased viscosity compared with the EA (without nanoparticles). Further studies investigating the impact of diverse filler concentrations on the properties of adhesives are suggested.