Flexural strength and degree of conversion of universal single shade resin-based composites.

Background/purpose: Recently, a group of universal single-shade resin-based composites (RBCs) has been developed to simplify the process of shade selection. Excellent mechanical and physical properties are crucial for the ultimate success and clinical longevity of restorations. Therefore, evaluating the properties of the single-shaded RBCs is imperative. This study aimed to determine the flexural strength (FS) and degree of conversion (DC) of universal single-shade RBCs. Materials and methods: In this study, four commercial RBCs were used; three universal single-shade RBCs; Omnichroma (OC), Charisma® Diamond ONE (CD), and Vittra APS Unique (VU), and a conventional nanohybrid composite Filtek™ Z250 XT (FT) which was used as a control. Sixty composite beams and 40 composite discs were used for FS and DC, respectively. A universal test machine with a three-point bending test was used to measure the FS, whereas the DC was measured using a Fourier-transform infrared spectrometer (FTIR). Three fractured specimens from each resin composite group were qualitatively analyzed using scanning electron microscopy. Results: ANOVA was used to compare the mean values of FS and DC among the four RBCs (OC, CD, VU, and FT). Highly significant differences were observed in the mean FS and DC values (F = 673.043, p < 0.001 and F (=782.4, p < 0.0001), respectively. The highest FS was observed in the CD group, followed by FT and VU groups; the lowest value was observed in the OC group. In addition, a statistically significant difference was identified in DC values. The highest DC value was observed in VU, followed by OC and CD, and the lowest DC value was observed in FT. Conclusion: Universal single-shade RBCs demonstrated a good FS, except for OC, which exhibited a significantly low FS. The DC of the universal single-shade RBCs was higher than that of the conventional nanohybrid composite restorative material.

PEEK and glass fiber post pushout bond strength and vickers hardness of canal disinfected with curcumin photosensitizer activated by microbubble emulsion and sodium-hypochlorite with EDTA.

AIMS: Impact of different post-space disinfectants (Saline, Sodium hypochlorite (NaOCl) followed by ethylene-diamine-tetra-acetic acid (EDTA) and curcumin activated by microbubble emulsion (MBE) on the Vickers hardness (VH) of root canal dentin and extrusion bond strength (EBS) of Glass fiber post (GFP) and PEEK post. METHODS: Ninety maxillary central incisors having fully formed roots were included. After the specimen's disinfection, root canal treatment was completed. Post space was prepared by removing gutta-percha using gates glidden drills. Teeth were then arbitrarily allocated into three groups based on the methods of disinfection regime used. Group 1: Saline, Group 2: NaOCl+ EDTA and Group 3: Curcumin activated by MBE (n = 30). Analysis of VH of radicular dentin was performed using a micro-Vickers tester on ten samples from each group. After post-space disinfection, twenty specimens from each group were further divided into two subgroups (n = 10) In group-1A 2A, and 3A, GFP was used. Whereas, prefabricated PEEK posts were used in 1B, 2B, and 3B subgroups. The PBS and failure modes were performed using a universal testing machine and stereomicroscope respectively. Data was analyzed using ANOVA and Tukey post hoc test to identify significant variations among groups concerning the MH and EBS of the different posts used (p = 0.05). RESULTS: Group 2 (5.25 % NaOCl + 17 % EDTA) (0.15 ± 0.02 GPa) treated specimens presented lowest scores of VH. However, Group 1 (Saline) irrigated canals displayed the highest scores of surface hardness (0.25 ± 0.07 GPa). Additionally, a cervical third of 3A (CP activated by MBE + GFP) (11.22 ± 0.79 MPa) presented the highest scores of bond integrity. Whereas Group 1B (Saline + PEEK post) treated specimens presented the lowest scores of PBS (4.15 ± 0.15 MPa). CONCLUSION: Curcumin activated by microbubble emulsion for disinfection of canal dentin demonstrated favorable VH. Similarly, glass fiber post-cemented in radicular walls disinfected with curcumin activated with MBE showed promising post-bond integrity to the canal dentin.

Effect of canal medicaments triple antibiotic paste, Bio-C Temp, and Nano-silver gel activated by visible blue light on canal dentin microhardness and extrusion bond strength of AH plus sealer: A SEM and EDX analysis.

AIM: Assessment of contemporary canal medicaments (Triple antibiotic paste (TAP), Bio-C Temp, and Nano silver gel activated by visible blue light on the dentin microhardness (MH) and push-out bond strength (PBS) of AH plus endodontic sealer. METHOD: Sixty extracted premolars were obtained and decontaminated. Canal cleaning and shaping were performed. The samples were randomly allocated into four groups based on the intracanal medicaments. Group 1= CH paste, Group 2= TAP, Group 3= Bio-C Temp, and Group 4= Nano-silver gel activated by visible blue light. MH assessment was performed using a Vickers Microhardness tester. Forty specimens, ten from each group underwent root canal obturation. PBS and failure mode evaluation were performed. ANOVA and Post Hoc Tukey test were utilized to conduct intra and inter-group comparisons. RESULTS: The maximum outcome of surface hardness was presented by Group-3 (Bio-C Temp®) specimens. However, minimum scores of MH were displayed by Group 1 (CH) treated teeth. The highest outcomes of EBS were exhibited by the cervical third of Group 3 (Bio-C Temp®) samples. The apical section of Group 4 Teeth with Nano Silver gel activated by visible blue light revealed the lowest scores of bond integrity. CONCLUSION: Bio-C Temp and TAP proved to be better intracanal medicament than other tested groups in terms of the push-out bond strength of the sealer. TAP displayed lower microhardness as compared to the Bio-C Temp.

Effect of different finishing and polishing systems on surface properties of universal single shade resin-based composites.

BACKGROUND: Recently, universal single-shade resin composites have become increasingly available in the dental market. The modification of their composition can have an inadvertent effect on their physical and surface properties, and subsequently determinantal effect on their clinical function and longevity. Therefore, this study aimed to evaluate the effect of different finishing and polishing (F/P) systems on surface roughness (Ra), surface gloss (GU), and Vickers microhardness (VMH) of universal single-shade RBCs. MATERIALS AND METHODS: Four commercial RBCs were used; the universal single-shade RBCs were Omnichroma, Charisma® Diamond ONE, and Vittra APS Unique, and a conventional nanocomposite Filtek™ Z250 XT was used as a control. The 3 F/P systems were Sof-Lex™ XT, Enhance®/PoGo®, and Diacomp® Plus Twist. A total of 160 discs were used for the 3 F/P system groups for all RBCs (n = 10). After F/P, the Ra, GU, and VMH were assessed. The data were analyzed using 2-way ANOVA at p-value < 0.05. RESULTS: Significant differences were found among the four RBCs and the 3 F/P systems (p < .000). Omnichroma showed the lowest Ra and acceptable GU, but the lowest VMH. Charisma showed the highest Ra, acceptable GU, and VMH. Vittra showed acceptable Ra, GU, and VMH and Filtek showed the highest GU, VMH, and acceptable Ra. CONCLUSION: Although conventional nanohybrid RBC (Filtek Z250 XT) showed better GU and VMH values, the universal single-shade RBCs demonstrated comparable surface properties. The highest GU & VMH and lowest Ra were achieved by Diacomp followed by Enhance and Soflex.

Bleached enamel reversal using grape seed extract, green tea, curcumin-activated photodynamic therapy, and Er: YAG on microleakage and bond integrity of composite material bonded to the enamel surface.

AIMS: Bleached enamel reversal using antioxidants sodium ascorbate (SA), Green tea extract (GTE), grape seed extract (GSE), Curcumin photosensitizer (CP) and Er: YAG laser on the adhesive strength and marginal leakage of composite material bonded to the bleached enamel surface. MATERIALS AND METHODS: Enamel surface of hundred and twenty sound human first premolar teeth was cleansed using pumice and bleached with 35 % hydrogen peroxide. The samples were randomly divided into 5 groups based on the antioxidants used. n = 20 Group 1 (Control): No antioxidant agent, Group 2: 10 % SA solution, Group 3: 6.5 % GSE, Group 4: 5 % GTE, Group 5: Er: YAG laser and Group 6: CP. Following reversal, the composite was built and cured for 40 s. All the specimens were stored in distilled water at room temperature for 1 day. Microleakage, SBS, and failure mode were analyzed. Kolmogorov-Smirnov test, one-way analysis of variance, and Tukey's multiple post hoc test were used to analyze the data statistically. RESULTS: Group 2 (SA) (20.11 ± 5.79 nm) exhibited minimum value of microleakage and highest SBS (10.22 ± 1.62 MPa). Whereas, Group 1 (No antioxidant agent) displayed maximum scores of marginal leakage (28.11±8.89 nm) and lowest SBS (7.02 ± 1.22 MPa). CONCLUSION: CP, GTE and GSE can be used as a potential alternative to the commonly used SA solution to reverse the negative impact of bleaching on the enamel surface. The use of reversal agents CP, GTE and GSE improves bond values with a decrease in microleakage scores However, future studies are still warranted to conclude the outcomes of the existing study.

Poly-Ether Ether-Ketone Post Conditioned with Sulfuric Acid, Rose Bengal Activated by Photodynamic Therapy and Sandblasting on Pushout Bond Strength to Radicular Dentin Luted with Methyl Methacrylate and Composite-Based Cement.

Objective: Assessment of post surface conditioners [sulfuric acid (SA), Rose Bengal (RB), and sandblasting (SB)] and different luting cements [methyl methacrylate (MMA)-based cement and composite-based cement] on pushout bond strength (PBS) of poly-ether ether-ketone (PEEK) post bonded to canal dentin. Materials and methods: Endodontic treatment was performed on 120 single-rooted human premolar teeth. The preparation of the post space was performed and 4 mm of gutta-percha was retained in the apical region of the root. One hundred and twenty PEEK posts were fabricated from a PEEK blank utilizing a Computer aided design-Computer aided manufacture (CAD-CAM) system. The PEEK posts were allocated randomly into four groups based on post surface conditioning (n = 30). Group A: SA, Group B: RB, Group C: SB, and Group D: No conditioning (NC). Each group was further divided into two subgroups based on the luting cement used for bonding (n = 15). Group A1, B1, C1, and D1 specimens were cemented using composite-based resin cement. However, Group A2, B2, C2, and D2 posts were luted with MMA-based resin cement. PBS assessment using a universal testing machine was performed. Failure modes were analyzed under a stereomicroscope. The data relating to the effects of surface treatment and luting types of cement were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc test (p = 0.05). Results: Coronal section of Group B2: RB+Super-Bond C&B [9.61 ± 0.75 megapascals (MPa)] displayed the highest bond scores of PEEK after root dentin. Whereas it was also discovered that Group D1: NC+Panavia®V5 (2.05 ± 0.72 MPa) presented the lowest PBS scores. Intergroup comparison analysis revealed that Group A2: SA+Super-Bond C&B and Group B2: RB+Super-Bond C&B displayed no significant difference in their bond scores. Conclusions: RB and SA possess the potential to be used as a PEEK post conditioner. MMA-based cement displayed better performance than composite-based cement.

Different Designs of Deep Marginal Elevation and Its Influence on Fracture Resistance of Teeth with Monolith Zirconia Full-Contour Crowns.

Background and objectives: Even with the demand for high esthetics, the strength of the material for esthetic applications continues to be important. In this study, monolith zirconia (MZi) crowns fabricated using CAD/CAM were tested for fracture resistance (FR) in teeth with class II cavity designs with varying proximal depths, restored through a deep marginal elevation technique (DME). Materials and Methods: Forty premolars were randomly divided into four groups of ten teeth. In Group A, tooth preparation was conducted and MZi crowns were fabricated. In Group B, mesio-occluso-distal (MOD) cavities were prepared and restored with microhybrid composites before tooth preparation and the fabrication of MZi crowns. In Groups C and D, MOD cavities were prepared, differentiated by the depth of the gingival seat, 2 mm and 4 mm below the cemento-enamel junction (CEJ). Microhybrid composite resin was used for DME on the CEJ and for the restoration of the MOD cavities; beforehand, tooth preparations were conducted and MZi crowns were and cemented using resin cement. The maximum load to fracture (in newtons (N)) and FR (in megapascals (MPa)) were measured using the universal testing machine. Results: The average scores indicate a gradual decrease in the load required to fracture the samples from Groups A to D, with mean values of 3415.61 N, 2494.11 N, 2108.25 N and 1891.95 N, respectively. ANOVA revealed highly significant differences between the groups. Multiple group comparisons using the Tukey HSD post hoc test revealed that Group D had greater DME depths and showed significant differences compared with Group B. Conclusions: FR in teeth decreased when more tooth structure was involved, even with MZi crowns. However, DME up to 2 mm below the CEJ did not negatively influence the FR. Strengthening the DME-treated teeth with MZi crowns could be a reasonable clinical option, as the force required to fracture the samples far exceeded the maximum recorded biting force for posterior teeth.

Effect of malachite green, ocimum sanctum, and Er, Cr: YSGG laser on antimicrobial activity against S.mutans and CAD disinfection bonded to resin restoration.

AIMS: Evaluation of survival of S.mutans and shear bond strength (SBS) of adhesive restorative material bonded to carious affected dentin (CAD) after using cavity disinfectant i.e., Er, Cr: YSGG (ECYL), (Nd: YAG) (NYL), Malachite green (MG), Ocimum sanctum (OS) in comparison to the conventional control chlorhexidine gluconate (CHX). MATERIALS AND METHODS: Seventy-five caries-affected mandibular third molars having ICDAS scores 4 and 5 were included. Carious infected dentin was eliminated and CAD surface was obtained. On twenty-five samples, an uncontaminated suspension of S. mutans strain ATCC 35,668 in Brain-Heart Infusion broth (BHI) was obtained after 12 h of incubation at 37 °C. Based on the disinfection regime used to sterilize the CAD surface, all the specimens were allocated into five different groups. (n = 15) Group 1: CAD disinfected with CHX, Group 2: CAD disinfected with ECYL, Group 3: CAD disinfected with NYL, Group 4: CAD disinfected with MG, and Group 5: CAD disinfected with OS. An assessment of the survival rate of S. mutans was performed. Fifty specimens were smeared with single-step adhesive bond followed by restoring the CAD surface using packable composite. SBS and failure mode were determined using a universal testing machine and stereomicroscope at 40x magnification. ANOVA and post-hoc Tukey-Kramer test was used for data analysis p = 0.05. RESULTS: Group 1: CHX-treated specimens displayed the lowest bacterial viability (0.11±0.03 CFU/mL). However, group 4: MG exhibited the highest bacterial survival (0.15 ± 0.09 CFU/mL). The highest and lowest SBS of resin adhesive bonded to disinfected CAD surface were exhibited by (group 5: OS) (21.48±1.39 MPa) and (group 3: NYL) (16.41±0.90 MPa) respectively (p>0.05). CONCLUSION: Ocimum sanctum seems to be promising in terms of its antibacterial efficacy against S.mutans and positive impact on SBS of resin adhesive to CAD surface.

Effectiveness of final cavity disinfectant terminalia chebula, malachite, and indocyanine green, against E. Faecalis and on the bond interface of fiber post to radicular dentin.

AIMS: Evaluation of antimicrobial efficacy of contemporary disinfection Malachite green (MG), Terminalia chebula (T. chebula), and Indocyanine green (ICG)) against E. faecalis and their effect on push-out bond strength (PBS) of glass fiber post (GFP) bonded to root dentin in comparison to conventional irrigation used (Sodium hypochlorite (NaOCl) + Ethylene diamine tetraacetic acid (17% EDTA). MATERIALS AND METHODS: Root canal treatment was initiated on sixty human single-rooted premolars and working length was established. The canals were enlarged using ProTaper universal system till F3. The prepared canals were obturated with Gutta-percha (GP) and AH Plus sealer followed by post-space preparation. Twenty canals contained a standard strain of E. faecalis (n=5 in each group) cultured overnight at 37 °C in BHI broth. All the samples were randomly allocated into four groups based on post-space irrigation. (n = 10) Group 1: 5.25% NaOCl+17% EDTA (Control), Group 2: 5.25% NaOCl + ICG, Group 3: 5.25% NaOCl + MG and Group 4: 5.25% NaOCl + T. chebula. Survival rates of E. faecalis were evaluated on the twenty specimens. GFP was placed on the remaining samples using self-etch dual-cure pastes and sectioning was performed in 1 mm thick slices. PBS and failure mode were analyzed using a universal testing machine and stereomicroscope. One-way analysis of variance (ANOVA) and Tukey multiple comparison t-tests were used for data analysis. (p = 0.05). RESULTS: 5.25% NaOCl+17% EDTA demonstrated (0.11±0.01 CFU/mL) the lowest survival rate of E. faecalis. However, Group 2 (5.25% NaOCl + ICG) exhibited the highest survival rate (0.52 ± 0.10). Furthermore, the coronal third of group 4 (5.25% NaOCl + T. chebula) (8.71±0.25 MPa) specimens demonstrated the highest PBS of GFP. However, an apical section of group 2 samples (5.25% NaOCl + ICG) (1.21±0.71 MPa) displayed the lowest outcome of bond integrity. CONCLUSION: Terminalia chebula when used as a final canal disinfectant seems to be promising in improving canal sterility and the bond strength of GFP to the root dentin.

Influence of Acidic Environment on the Hardness, Surface Roughness and Wear Ability of CAD/CAM Resin-Matrix Ceramics.

This study aimed to measure the effect of storage environment on the hardness, surface roughness and wear ability of CAD/CAM resin-matrix ceramics. A total of 200 rectangular-shaped specimens were obtained by sectioning 5 CAD/CAM blocks; Crystal Ultra (CU), Vita Enamic (VE), Lava Ultimate (LU), Cerasmart (CS) and Vita blocks Mark II (MII). Microhardness and surface roughness were measured at baseline and after 7 days of immersion either in saliva or cola (n = 10). The wear ability of the CAD/CAM materials against steatite-ceramics antagonist was determined using a chewing simulator. The data were statistically analyzed using factorial ANOVA followed by post hoc Bonferroni multiple comparison tests (p < 0.05). The independent factors significantly influenced the microhardness and surface roughness (p < 0.05). The highest VHN was observed in MII at baseline (586.97 ± 13.95), while CU showed the lowest VHN after 7 days of immersion in cola (68.3 ± 1.89). On the contrary, the highest Ra was observed after 120,000 chewing cycles for the VE specimens (1.09 ± 0.43 µm) immersed in cola, while LU showed the lowest Ra at baseline (0.07 ± 0.01 µm). The highest % mass loss of the antagonist was observed with MII immersed in cola (1.801%), while CS demonstrated the lowest % mass loss of 0.004% and 0.007% in AS and cola, respectively. This study confirms that the surface properties of tested CAD/CAM materials are susceptible to degradation in an acidic environment except for hardness and wear of CS material.

Biaxial flexural strength of various CAD-CAM glass-ceramic materials.

PURPOSE: To evaluate and compare the flexural strength of three CAD-CAM glass-ceramic materials and to investigate the effect of various surface treatments on their flexural strength. METHODS: 120 rectangular specimens were fabricated from three different types of CAD-CAM ceramic blocks and were divided into three groups: zirconia-reinforced lithium silicate (Celtra Duo, Group 1), leucite-reinforced glass-ceramic (IPS Empress CAD, Group 2), and lithium disilicate ceramic (IPS e.max CAD, Group 3). Dimensions of the specimens were standardized to 14.5x12.5 mm and 1.5 mm thickness. Specimens in each group were randomized into four subgroups. The first subgroup (NS) did not undergo any surface treatment; the second subgroup (P) underwent polishing only; the third subgroup (G) underwent glazing only; and the fourth subgroup (PG) underwent both polishing and glazing surface treatments. Biaxial flexural strength (FS) testing was performed until fracture occurred; FS was calculated in MPa. All analyses were performed using SPSS version 24. RESULTS: Group NS2 showed the lowest FS (89.34 ± 25.30 MPa). Group PG3 showed a significantly higher FS (365.38 ± 52.52 MPa) than Group P3 (268.15 ± 48.34). There was a statistically significant difference among the material groups for each surface treatment: IPS e.max CAD showed the highest FS, which was significantly greater than that of both Celtra Duo and IPS Empress CAD. The combination of polishing and glazing surface treatment resulted in significantly higher flexural strength than polishing alone for all three materials tested. For each material, no significant difference was found between the following surface treatments: control and polishing-only surface treatments; glazing-alone and the combination of polishing and glazing surface treatments. For each surface treatment, Celtra Duo showed significantly lower flexural strength than IPS e.max CAD. However, it displayed higher flexural strength than IPS Empress CAD, although the difference was only significant for glazing and the combination of polishing and glazing. CLINICAL SIGNIFICANCE: This study provides the clinician with an estimate of the flexural strength of glass-ceramic materials and shows how various surface treatments affect their strength.

Influence of contemporary CAD-CAM milling systems on the fit and adaptation of partially stabilized Zirconia fixed partial dentures.

OBJECTIVE: To evaluate marginal fit and internal adaptation of three-unit Zr frameworks fabricated from four Zr CAD/CAM milling systems. METHODS: Fixed partial denture models were replicated (40 stone models) using Polyvinyl Siloxane impression material (PVS) and type IV stone for Zr framework fabrication. FPDs were milled with four CAD/CAM systems, Group-II: LAVAL Zirconia milled by LAVA , Group-2: Vita In-Ceram YZ milled by Cerec®, Group-3: Zirconia milled by GM1000 and Group-4: Zirconia milled by DWX-50N. Twelve marginal gap measurements per framework were performed at pre-established points, with a metallurgical microscope (Zeiss, Germany) at 500X magnification. Eight measurements of cement space per section were performed for adaptation. Data was analyzed using ANOVA and Tukey post hoc test. RESULTS: Zirconia FPD frameworks exhibited gaps ranging from 16 to 50.1 µm for marginal fit and 26.8 to 102.5 µm for internal adaptation. Group-3 [20.8 (8.3) µm & 50.3 (11.4) µm] and Group-4 [16.0 (4.0) µm & 40.2 (8.8) µm] specimens showed significantly lower marginal fit and internal adaptation gaps compared to Group-I [50.1 (13.4) µm & 100.5 (16.7) µm] and Group-2 [38.9 (8.2) µm & 102.5 (13.4) µm] specimens respectively. CONCLUSIONS: Different CAD-CAM systems for fabrication of Zr FPD frameworks displayed a significant influence on marginal fit and internal adaptation of restorations.

Effects of Different Air Particle Abrasion Protocols on the Biaxial Flexural Strength and Fractography of High/Ultra-Translucent Zirconia.

In this study, the biaxial flexural strength (BFS) and fractography of high/ultra-translucent monolithic zirconia ceramics subjected to different mechanical surface pretreatments were evaluated. A total of 108 disc-shaped samples (12 mm diameter, 1.2 mm thickness) of three zirconia materials (5Y-ZP KATANA Zirconia UTML (ML), 3Y-TZP DD Bio ZX2 (DB), and 5Y-ZP DD cube X2 (DC)) were used. The BFS was investigated after subjecting the samples to surface treatment using air abrasion particles of two types (aluminum oxide or glass microbeads). The data were analyzed using two-way analysis of variance, followed by Scheffe's post hoc test for multiple comparisons. The mean ± standard deviation BFS for DB was highest after treatment with 50 µm Al2O3 (1626.05 ± 31.9 MPa), with lower values being observed following treatment with 50 µm glass microbeads (1399.53 ± 24.2 MPa) and in the control sample (1198.51 ± 21.1 MPa). The mean ± standard deviation (SD) BFSs for DC and ML were the highest in the control groups. Surface air abrasion with 50 µm Al2O3 particles and 2 bar pressure is recommended for 3Y-TZP translucent zirconia, while no abrasion of 5Y-ZP translucent zirconia ceramic.

Self-perceived competency of the medical faculty for E-Teaching during the COVID-19 pandemic.

BACKGROUND: The aim of this study was to evaluate the self-perceived competency (FSPC) of medical faculty in E-Teaching and support received during the COVID-19 pandemic. METHODS: An online well-structured and validated faculty self-perceived competency questionnaire was used to collect responses from medical faculty. The questionnaire consisted of four purposely build sections on competence in student engagement, instructional strategy, technical communication and time management. The responses were recorded using a Likert ordinal scale (1-9). The Questionnaire was uploaded at www.surveys.google.com and the link was distributed through social media outlets and e-mails. Descriptive statistics and Independent paired t-test were used for analysis and comparison of quantitative and qualitative variables. A p-value of ≤0.05 was considered statistically significant. RESULTS: A total of 738 responses were assessed. Nearly 54% (397) participants had less than 5 years of teaching experience, 24.7% (182) had 6-10 years and 11.7% (86) had 11-15 years teaching expertise. 75.6% (558) respondents have delivered online lectures during the pandemic. Asynchronous methods were used by 61% (450) and synchronous by 39% (288) of participants. Moreover, 22.4% (165) participants revealed that their online lectures were evaluated by a structured feedback from experts, while 38.3% participants chose that their lectures were not evaluated. A significant difference (p < 0.01) was found between FSPC scores and online teaching evaluation by experts. The mean score of FSPC scale was 5.62±1.15. The mean score for student's engagement, instructional strategies, technical communication and time management were of 5.18±1.60, 5.67±1.61, 5.49±1.71 and 6.12±1.67 respectively. CONCLUSIONS: Medical faculty members were found somewhat competent in E-teaching for student engagement, instructional strategy, technical communication and time management skills. Faculty receiving feedback was more competent in comparison to peers teaching without feedback.

Influence of curing duration and mixing techniques of bulk fill resin composites on bi-axial flexural strength and degree of conversion.

OBJECTIVES: The aim was to assess the influence of polymerization duration, method and resin manipulation techniques on the biaxial flexural strength (BFS) and degree of conversion (DC) of bulk fill resin composites (BFRC). METHODS: One hundred and eighty disc specimens were fabricated using MultiCore (MC) and Core-It (CI) bulk fill resin composite. Each material group, specimens were divided into nine subgroups based on curing methods (Light cure for 10 and 20 s; and auto-cure) and mixing techniques (first auto-mix, second automix, and hand mix). BFS was tested with a ball indenter at a crosshead speed of 0.50 mm/min. DC was assessed for MC and CI materials for 10 s and 20 s light cure; and auto cure specimens using Fourier Transform-Infrared Spectroscopy (FTIR). Statistical data comparisons were performed using ANOVA, Bonferroni and Tukey-Kramer tests. RESULTS: For MC and CI, BFS was highest in 10 s light cure specimens, however comparable to specimens cured for 20 s (p > 0.05). Auto cure specimens showed lower BFS than light cured samples for both materials (p < 0.05). Hand mixed specimens showed significantly compromised BFS compared to automix technique for MC and CI. DC % was comparable for 10 s and 20 s light cure methods for both materials (p > 0.05), which was higher than DC % of auto cure bulk fill resins (p < 0.05). CI showed higher DC % and BFS compared to MC bulk fill resin composite. CONCLUSION: Photo-polymerization duration of 10 and 20 s showed similar outcomes for BFS and DC %; and BFS for auto-mixed resins (MC and CI) was significantly higher than hand mixed resin. BFS and DC was higher in photopolymerized groups as compared to auto-cured resin regardless of the manipulation technique for both materials (MultiCore and Core it).

Influence of milling systems and marginal configurations on the fit of yttrium stabilized tetragonal zirconia polycrystals (Y-TZP)' copings.

OBJECTIVE: The aim of this study was to evaluate marginal fit of yttrium tetragonal zirconia polycrystals (Y-TZP)' copings with different finish line designs fabricated with various digital scanners and milling systems. METHODS: Three model plastic teeth were prepared with three finish line designs: Design-1, continuous chamfer; Design-2, chamfer with shallow depression; Design-3, chamfer with deep depression. The "master models" were replicated using elastomeric polyvinyl siloxane impression material and poured in type IV stone generating 90 dies, 30 dies for each design. Dies were scanned and copings were milled utilizing three digital scanners and computer-aided design/computer-aided manufacturing (CAD/CAM) systems: System-1, InEos Red Scan (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); System-2, Cerec® AC Connect with BlueCam (Sirona Dental Systems, Germany), Vitablocks® Mark II (VITA, Germany) copings milled by Cerec® inLab (Sirona Dental Systems, Germany); and System-3, NobleProcera™ Optical Scanner (NobleBiocare™), procera zirconia coping milled by a Noble Procera™ milling machine (NobleBiocare™). Copings were seated on their respective "master models" and secured with uniform force. Eight measurements per coping were performed at pre-established points, with a metallurgical microscope (Zeiss, Germany) connected to a high precision digital video-micrometer (Javelin JV6000, California, USA) at 200 × magnification. RESULTS: The tested systems demonstrated marginal gaps ranging from 12.4 to 26.6 µm. Results for marginal fit of milled copings fabricated using three systems with different finish line designs differed significantly (p < 0.05). Procera zirconia copings scanned and milled with NobleProcera™ exhibited significantly lower marginal gaps compared to other specimen groups. However, InEos Red Scan/Vitablocks® Mark II/Cerec® inLab showed maximum marginal gaps among the study specimens. CONCLUSIONS: CAD-CAM manufactured Y-TZP' copings exhibited marginal gaps ranging from 12.49 to 26.6 µm. The CAD-CAM fabrication system was a significant factor influencing the marginal misfit of Y-TZP' copings. Margin design exhibited system dependent influence on the marginal misfit. Marginal misfit observed for all systems were within clinically acceptable parameters.

Graphene oxide nano-filler based experimental dentine adhesive. A SEM / EDX, Micro-Raman and microtensile bond strength analysis.

AIM: The study aimed to assess graphene oxide (GO) adhesive and its dentin interaction using scanning electron microscopy (SEM), MicroRaman spectroscopy and Microtensile bond strength (µTBS). MATERIALS AND METHODS: Experimental GOA and control adhesives (CA) were fabricated. Presence of GO within the experimental adhesive resin was assessed using SEM and Micro-Raman spectroscopy. Ninety specimens were prepared, sixty teeth were utilized for µTBS, twenty for SEM analysis of interface for CA and GOA and ten were assessed using microRaman spectroscopy. Each specimen was sectioned and exposed dentine was conditioned (35% phosphoric acid) for 10 s. The surface was coated twice with adhesive (15 s) and photopolymerized (20 s). Composite build-up on specimen was photo-polymerized. Among the bonded specimens, thirty specimen were assessed using Micro-Raman spectrometer, SEM and energy dispersive X-ray spectroscopy (EDX), whereas remaining specimens were divided in to three sub-groups (n = 10) based on the storage of 24 h, 8 weeks and 16 weeks. µTBS testing was performed at a crosshead speed of 0.5 mm/min using a microtensile tester. The means of µ-tbs were analyzed using ANOVA and post hoc Tukey multiple comparisons test. RESULTS: No significant difference in µTBS of CA and GOA was observed. Storage time presented a significant interaction on the µTBS (p < 0.01). The highest and lowest µTBS was evident in CA (30.47 (3.55)) at 24 h and CA (22.88 (3.61)) at 18 weeks. Micro-Raman analysis identified peaks of 1200 cm-1 to 1800 cm1, D and G bands of GO nanoparticles in the resin. Uniform distribution of graphene oxide nanoparticles was present at the adhesive and hybrid layer. CONCLUSION: GO showed interaction within adhesive and tooth dentin similar to CA, along with formation of hybrid layer. In ideal conditions (absence of nanoleakage), graphene oxide modified adhesive shows comparable bond strength and durability of resin dentine bond.

Repair strength and surface topography of lithium disilicate and hybrid resin ceramics with LLLT and photodynamic therapy in comparison to hydrofluoric acid.

AIM: The aim was to compare the repair bond strength and surface topography of lithium disilicate ceramics (LDC) and hybrid resin ceramics (HRC) using different surface conditioning treatments [low level laser therapy (LLLT), photodynamic therapy (PDT), hydrofluoric acid (HF) with silane and air abrasion (AA) and silane]. MATERIAL AND METHOD: Sixty specimens each of LDC and HRC were used. Discs were prepared for each group (6 × 2 mm), conditioned using different regimes. Specimens in group 1 and 5 were laser irradiated using Er,Cr:YSGG (ECYL), group 2 and 6 were conditioned using methylene blue photosensitizer (PDT), group 3 and 7 surface was treated with hydrofluoric acid and silane (HFA-S), group 4 and 8 conditioned with Al2O3 air abrasion and silane (AA-S). A Porcelain Repair Kit was used according to manufacturer recommendation in all samples. Peak universal bond adhesive was rubbed on ceramic surface and then bonded with composite resin. For shear bond strength testing the specimens were placed in a universal testing machine. A stereomicroscope at 40x magnification was used to analyse failure pattern. Five specimens in each group after surface treatment were evaluated for surface changes and topography using scanning electron microscopy. The mean repair bond strength was calculated using ANOVA and Tukey's post hoc test at a significance level of (p < 0.05). RESULT: The highest repair bond strength was observed in group 3 (LDC) (20.57 ± 3.58 MPa) (HFA-S), whereas, the lowest score was displayed in Group 2 (LDC) using methylene blue photosensitizer (MBPS) (12.18 ± 1.08 MPa). Similarly, in HRC the highest repair SBS was presented in group 8 (AA-S) (20.52 ± 2.51 MPa) and the lowest SBS values were exhibited by PDT treated group 6 (13.22 ± 0.62 MPa). CONCLUSION: A combination of mechanical and chemical surface treatments should be used in order to achieve adequate repair bond strength between resin composites and ceramic interface of LDC and HRC.

Antimicrobial efficacy of silver diamine fluoride in comparison to photodynamic therapy and chlorhexidine on canal disinfection and bond strength to radicular dentin.

AIM: To assess the antimicrobial efficacy of Silver diamine fluoride (SDF), Sodium hypochlorite (NaOCl), Chlorhexidine (CHX) and Photodynamic therapy (PDT) in radicular dentin and subsequent bond strength of Fiber reinforced composite post (FRCP) to radicular dentin. MATERIAL AND METHODS: Forty extracted premolars were disinfected and decoronated up-to cement-o-enamel junction (CEJ). Canals were instrumented using crown-down technique, dried and filled with gutta percha. Post space was prepared with the help of peso reamers and inoculated with E. faecalis. Samples were randomly allocated into four groups based on chemical irrigation (n = 10). Group 1, canal disinfected with (PDT, MB), group 2 (5.25 % NaOCl +17 % EDTA), group 3 (3.8 % SDF) and group 4 (CHX). Specimens were tested with confocal laser scanning microscopy analysis (CLSM) to confirm the presence of E. faecalis. Fibre post were luted in root canal and sectioned at three levels (apical, middle and coronal). Push-out test was performed and failure analysis of debonded surfaces was evaluated using stereomicroscope. Live and dead cells after exposure were calculated in percentage. One-way analysis of variance (ANOVA) assessed the means and standard deviations of extrusion bond strength (EBS). Tukey multiple comparison tests was used to compare means of bond strength (p = 0.05). RESULTS: The maximum antimicrobial efficacy against E. faecalis was observed in group 2 which included canal disinfected with 5.25 % NaOCl and 17 % EDTA (64.41 ±â€¯1.22). Similarly, CHX showed lowest effectiveness as canal irrigant against E.faecalis (58.29 ±â€¯2.41). Intragroup comparison revealed highest bond strength for group 2 at all three level. Similarly, the lowest EBS was found in CHX group. Inter-group comparison confirmed comparable EBS at all root levels (apical, middle and coronal) for group 2 and group 3 (p > 0.05). CONCLUSION: Radicular dentin treated with 5.25 % NaOCl and 17 % EDTA displayed highest antimicrobial and bond strength scores. SDF and PDT can potentially be used in canal irrigation.

Management of caries affected dentin (CAD) with resin modified glass ionomer cement (RMGIC) in the presence of different caries disinfectants and photosensitizers.

AIM: To evaluate Shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) on caries affected dentin after using different cavity disinfectants i.e., chlorhexidine gluconate (CHX), Er,Cr:YSGG laser (ECYL) and photodynamic therapy (PDT). MATERIAL AND METHODS: Total 50 freshly extracted mandibular molars were obtained through non-traumatic extraction. All the samples were rooted vertically within self-cure acrylic resin blocks up to cervical level so that only coronal portion remain visible. Silicon carbide grinding discs 1200 and 600 grits was used to prepare the teeth. However affected dentin remains untouched. All samples were randomly distributed in to five groups (n = 10). Group 1: 2 % CHX, Group 2: 2 % solution of methylene blue (MB) and Diode laser, Group 3: Indocyanine green (ICGP) solution and Diode laser, Group 4: curcumin (CP) and LED curing unit, Group 5: ECYL. The specimens were then stored at a temperature of 37 °C for 24 h and 100 % humidity before specimens were placed in to universal testing machine for the SBS measurements. Failure mode examination was performed by a stereomicroscope. ANOVA test analyze inter group comparison. Tukey HSD test was used to analyze multiple group comparison. The level of significance was set at p < 0.05 value. RESULTS: Among all the groups, group 1 (control, CHX treated) demonstrated highest SBS value (18.31 ±â€¯1.06 MPa). Whereas lowest SBS was displayed by group 2 (PDT, MB) (12.31 ±â€¯0.57 MPa). Dentin disinfected with group 4 (PDT, CP) (16.86 ±â€¯0.97 MPa) and group 5 (ECYL) (17.39 ±â€¯2.26) showed comparable result to that of CHX (p > 0.05). CONCLUSIONS: Bond strength of RMGIC bonded to CHX disinfected caries affected dentin was highest among study groups. Use of MB showed lowest shear bond strength outcomes. Moreover, application of ECYL and curcumin with LED showed bond strengths comparable to CHX control.