Use of Nd:YVO4 laser, photodynamic therapy, sulfuric acid and sand blasting on improving bond integrity of PEEK to resin cement with adhesive.

AIM: The present study aimed to inspect and compare several PEEK surface treatments modifications using Photodynamic therapy (PDT), Neodymium-doped yttrium orthovanadate (Nd:YVO4) laser, Sulphuric acid (H2SO4), and sandblasting (SB) when bonded to composite resin via an adhesive system MATERIAL AND METHODS: One hundred disk-shaped PEEK specimens were prepared by CAD-CAM milling and randomly distributed into five groups based on surface treatment methods: group1: Control (no treatment), group 2: PDT, group 3: Nd:YVO4 laser, group 4: H2SO4 and group 5 sandblasting. Later bonding was pursued using resin cement with an adhesive system. Measurements of surface roughness employing a surface profilometer, water contact angle by the static drop method, SBS by universal Testing machine, and failure modes of de-bonded PEEK specimens by Stereomicroscope were attained. Execution of statistical analysis was performed by two-way analysis of variance ANOVA and Tukey's post hoc test (p>0.05). The Shapiro-Wilk normality test and Bartlett's test for homoscedasticity were also performed. RESULTS: The highest SBS was exhibited by Nd:YVO4 laser (16.33 ± 0.71 MPa) and the lowest SBS was observed in the control group (9.4 ± 1.02). However, PEEK specimen luted with resin cement treated with PDT (16.21 ± 0.14 MPa) and H2SO4 (15.23 ± 0.63 MPa) displayed a comparable SBS to Nd:YVO4 laser (p>0.05). The results of Ra exhibited that PEEK material when exposed to Nd:YVO4 laser (15.252 ± 1.581 µm) unveiled the highest Ra. Nd:YVO4 laser (131.25 ± 2.9 µm) and PDT (130.24 ± 3.7 µm) showed comparable WCA values (p>0.05).Adhesive failure was dominant. CONCLUSION: PEEK surface treated with photodynamic therapy and Neodymium-doped yttrium orthovanadate laser and bonded to composite resin via an adhesive system significantly improved shear bond strength, surface roughness, and water contact angle.

Efficacy of chlorhexidine, photosensitizers, green tea extract, and propolis on bond integrity and microleakage of caries-affected dentin: An in-vitro study.

AIM: The current study aimed to evaluate the efficacy of chlorhexidine (CHX), phycocyanin photosensitizer (PC), green tea extract (GTE), and propolis (PP) on the adhesive bond integrity and microleakage of caries-affected dentin (CAD) using etch and rinse adhesive system. MATERIAL AND METHODS: A sum of 80 extracted human mandibular molars was collected and assessed using ICDAS criteria. Randomly CAD samples were treated with different disinfectants (n = 20) each CHX, PC, GTE, and PP. After ensuring disinfection, specimens were rehabilitated with bulk-fill composite resin employing etch and rinse adhesive system. SBS testing was performed by engaging (n=10) specimens in a universal testing machine. Microleakage analysis was performed by using the dye penetration technique.A stereomicroscope under 40× magnification was utilized for analyzing failure modes. Statistical analysis was accomplished by using the ANOVA and Tukey's post hoc tests (p<0.05). RESULTS: Highest bond strength was displayed by CAD disinfection with CHX and bonded to resin cement (15.33 ± 0.14 MPa). Whereas, the lowest SBS bond value was presented by Group 2 dentin surface disinfection with PC. CAD disinfected with GTE, PP and CHX demonstrated comparable SBS(p>0.05). The maximum microleakage score was exhibited when CAD bonded to resin cement disinfected with PP. While the minimum microleakage score was unveiled CAD bonded to resin cement sanitized with CHX CONCLUSION: Caries-affected dentin bonded to resin cement, chlorhexidine exhibited the highest adhesive shear bond strength with a minimal microleakage score using etch and rinse adhesive system.

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.

Dietary Factors Influencing the Caries Status of Adults in Karachi, Pakistan: Initial Findings.

Objective: The objective was to identify the relationship between the dietary factors related to increases in the number of dental caries among an adult population group. Methods: A cross-sectional study was conducted involving adult patients and their accompanying person, aged 18 years and above (n = 1730) visiting the dental outpatient department (OPD) of a public sector tertiary healthcare institute in Karachi, Pakistan. A 39-item Food Frequency Questionnaire (FFQ) was administered to the patients, followed by a dental caries assessment using Radke's WHO criteria. Caries assessment data were transformed into the DMFT Index (D = decayed, M = missing, F = filled teeth). Factor analysis (FA) was performed using Stata v. 11.0, followed by assessing the internal consistency of the FFQ. Multilogistic analysis was performed to explore the association between dental caries (cut-off = 5) and other independent variables, considering a p-value < 0.05 as significant. Results: The mean age of participants in the group was 32.65 ± 10.49 years. The number of female participants (934; 54%) was higher than male participants (796; 46%). Of the total, 951 (52%) participants were married. The internal consistency value for the FFQ, as measured by Cronbach's alpha, was 0.80. In addition to age and gender, out of four dietary patterns, only "cereals" were found to be significantly (p < 0.05) associated with increased DMFT. Conclusion: This study established that the high intake of cereals is a contributory factor to the high prevalence of dental caries among adults.

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.

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.

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.