Remineralizing pretreatment using Casein phosphopeptide-amorphous calcium phosphate fluoride, self-assembling peptide, and Nanohydroxyapatite gel activation via invisible infrared light on the dentin microhardness and micro shear bond strength to the composite restoration.

AIM: Different remineralizing pretreatments Casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF), tricalcium phosphate fluoride (TCP-F), self-assembling peptide (SAP) P11-4 and 10% Nanohydroxyapatite (nHA) gel activation via invisible infrared light on the dentin microhardness (MH) and micro shear bond strength (µSBS) of composite restoration. METHODS: Seventy-five human molar teeth were collected and the dentinal surface of all the samples was exposed to different demineralizing solutions. (n=15) Group 1 (demineralized dentin), Group 2 (CPP ACP), Group 3 (TCP-F), Group 4 (SAP P11-4), Group 5 (nHA gel activation via invisible infrared light). MH assessment was performed using Vickers hardness. Each group of 10 samples was subjected to composite restoration buildup and µSBS were tested. The debonded samples were then observed under a stereo-microscope for failure analysis. ANOVA was conducted, along with Tukey's post hoc analysis, to examine the µSBS of composite and MH of the remineralized surface. RESULTS: nHA gel activation via invisible infrared light pretreated specimens showed the maximum outcomes of surface hardness (331.2 ± 77.3) and bond strength (10.38 ± 2.77). However, Group 4 (SAP P11-4) (148.3 ± 29.2) remineralized dentin displayed minimum scores of MH and µSBS (5.88 ± 1.01). CONCLUSION: Remineralizing pretreatment nHA gel activation via invisible infrared light and casein phosphopeptide-amorphous calcium phosphate fluoride seem to improve the dentin MH and µSBS of the composite restoration.

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 Hydroxyapatite Nanospheres in Dentin Adhesive on the Dentin Bond Integrity and Degree of Conversion: A Scanning Electron Microscopy (SEM), Raman, Fourier Transform-Infrared (FTIR), and Microtensile Study.

An experimental adhesive incorporated with different nano-hydroxyapatite (n-HA) particle concentrations was synthesized and analyzed for dentin interaction, micro-tensile bond strength (µTBS), and degree of conversion (DC). n-HA powder (5 wt % and 10 wt %) were added in adhesive to yield three groups; gp-1: control experimental adhesive (CEA, 0 wt % HA), gp-2: 5 wt % n-HA (HAA-5%), and gp-3: 10 wt % n-HA (HAA-10%). The morphology of n-HA spheres was evaluated using Scanning Electron Microscopy (SEM). Their interaction in the adhesives was identified with SEM, Energy-Dispersive X-ray (EDX), and Micro-Raman spectroscopy. Teeth were sectioned, divided in study groups, and assessed for µTBS and failure mode. Employing Fourier Transform-Infrared (FTIR) spectroscopy, the DC of the adhesives was assessed. EDX mapping revealed the occurrence of oxygen, calcium, and phosphorus in the HAA-5% and HAA-10% groups. HAA-5% had the greatest µTBS values followed by HAA-10%. The presence of apatite was shown by FTIR spectra and Micro-Raman demonstrated phosphate and carbonate groups for n-HA spheres. The highest DC was observed for the CEA group followed by HAA-5%. n-HA spheres exhibited dentin interaction and formed a hybrid layer with resin tags. HAA-5% demonstrated superior µTBS compared with HAA-10% and control adhesive. The DC for HAA-5% was comparable to control adhesive.

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.

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.

Influence of electronic nicotine delivery systems (ENDS) in comparison to conventional cigarette on color stability of dental restorative materials.

OBJECTIVE: The use of Electronic Nicotine Delivery Systems (ENDS) is increasing rapidly. However, its discoloring effect on dental restorations is not known. This study aimed to evaluate the effect of ENDS aerosol when compared to conventional cigarette smoke (CS) on the color stability of dental ceramic (DC) and resin composite (RC). METHODS: This research project was conducted from November 2018 to May 2019. In this study 30 discs each for DC and RC materials were fabricated to be equally divided into groups of exposure to CS, ENDS aerosol and storage in distilled water (No smoke; NS) respectively (n=10). Specimens were exposed for a total of 7 days, with a rate of 10 cycles per day, each cycle represented 10 puffs. The color change was assessed using the CIELAB color space, by calculating ΔE. Data was analysed using ANOVA and multiple comparisons test. RESULTS: Ceramic specimens in CS (2.422 ± 0.771) and ENDS (2.396 ± 0.396) groups showed comparable ΔE (color change) (p=0.992). Similarly, composite specimens in CS (42.871 ± 2.442) and ENDS (46.866 ± 3.64) groups showed comparable ΔE (p>0.05). NS specimens in both composite and ceramic samples showed lower ΔE than CS and ENDS specimens respectively. CONCLUSIONS: Aerosol from Electronic nicotine delivery systems (ENDS) showed similar discoloration levels as cigarette smoking (CS). The level of discoloration for ceramic samples for both ENDS and CS was below clinically perceptible levels (Mean ΔE < 2.5). Discoloration of composite resin due to CS and ENDS was visually perceptible (Mean ΔE > 4.0).

Efficacy of chlorhexidine, Er Cr YSGG laser and photodynamic therapy on the adhesive bond integrity of caries affected dentin. An in-vitro study.

AIM: To evaluate the adhesive bond integrity (shear bond strength-SBS) of composite resin bonded to carious dentin using chlorhexidine gluconate (CHX), Er,Cr:YSGG laser (ECYL) and photodynamic therapy (PDT). MATERIAL AND METHODS: Thirty carious and ten non-carious mandibular teeth were collected through non-traumatic extraction. All samples were embedded in polyvinyl cross-sections to the cemento-enamel junction. The preparation of caries-affected dentin was performed by grinding the specimens using silicon carbide discs. All specimens were randomly allocated in to four groups (n = 10). Group 1, non-affected dentin with no disinfection; Group 2, caries affected dentin treated with 2% CHX; Group 3, affected dentin disinfected with PDT [100 mg/L methylene blue solution (MBS) and Diode laser]; Group 4, affected dentin treated with ECYL. Self-etch adhesive was smeared on all specimens for 10 s and photopolymerized for 10 s. All specimens were placed in an incubator with humid environment for 24 h at 37 °C followed by positioning in universal testing machine for SBS testing. Failure mode examination of debonded samples was performed by a stereomicroscope. Analysis of variance (ANOVA) was used for inter group comparison through mean and standard deviation of each group. For multiple group comparison Tukey HSD was employed. Level of significance was established at p < 0.05. RESULTS: The highest SBS value was observed in group 1 (24.98 ± 1.59 MPa). Whereas, the lowest bond strength was displayed by group 3 (14.22 ± 1.40 MPa) specimens. Lased dentin in group 4 (15.89 ± 3.22 MPa) exhibited SBS values comparable to group 3 (14.22 ± 1.40 MPa). Group 2 (CHX-18.25 ± 1.29 MPa) exhibited statistically significant difference compared to all experimental groups (p < 0.05). CONCLUSIONS: Adhesive bond strength of disinfected carious dentin was higher with CHX treatment as compared to Photodynamic therapy and Er,Cr: YSGG laser treatment. Carious dentin showed lower bond strength to composite resin as compared to non-carious dentin.

Influence of different photosensitizers on push-out bond strength of fiber post to radicular dentin.

BACKGROUND: To evaluate the effect of different photosensitizer on extrusion bond strength of glass fiber post to radicular dentin. MATERIAL AND METHODS: Forty maxillary and mandibular central incisors were disinfected and decoronated. Mechanical instrumentation of canal was performed using protaper NiTi. Shaping and cleaning of canal comprised of S1, S2, SX with finishing files F1 and F2, followed by continuous irrigation. Canals were dried and obturated with gutta percha. Peso reamers were used to prepare post space. Based on the photosensitizers (PS) used, the samples were divided into three groups (n = 10). Group 1: treated with methylene blue photosensitizer (MBP) at 50 mg/l, Group 2: Curcumin photosensitizer (CP) at 500 mg/l, Group 3: canal space was filled with Toluidine blue photosensitizer (TB) at 100 mg/l. All photosensitizers were activated using different lasers. The samples in group 4 (control) were irrigated using 5.25% sodium hypochlorite (NaOCl) + 17% ethylenediamine tetra acetic acid (EDTA). Posts were cemented and teeth were sectioned into coronal, middle and apical sections. All sections were placed in universal testing machine to evaluate extrusion bond strength in megapascal (MPa). Fracture pattern analysis of samples were seen under stereomicroscope at 50x magnification and categorized into adhesive, cohesive and admixed. Assessment of extrusion bond strength was performed by one-way analysis of variance (ANOVA) and Tukey multiple comparison test (p = 0.05). RESULTS: The highest bond strength was achieved in group 2, including samples treated with curcumin photosensitizer (CP) at all three root levels; cervical (9.01 ±â€¯1.62 MPa), middle (7.95 ±â€¯0.75 MPa) and apical (5.81 ±â€¯0.15 MPa). Whereas, the lowest extrusion bond strength was observed in group 4 (canal irrigated with conventional 5.25% NaOCl +17% EDTA) at coronal (6.10 ±â€¯1.77 MPa), middle (5.11 ±â€¯0.75 MPa) and apical one-thirds (3.65 ±â€¯0.14 MPa). Intra group comparison revealed decrease in extrusion bond strength from coronal to apical direction. Moreover, both group 2 and group 3 showed statistically significant difference to samples in control group and group 1. (p < 0.05). CONCLUSION: TB and CP at concentration of 100 mg/l and 500 mg/l has the potential to be used as an alternate to conventional cleaning regime. TB and CP at this concentration when activated with PDT is likely to improve extrusion bond values.

Immunohistochemical study of dental pulp cells with 3D collagen type I gel in demineralized dentin tubules in vivo.

Dental pulp cells (DPCs) represent good candidates for the regeneration of dental tissue. This study aimed to evaluate the growth and differentiation potential of DPCs cultured inside demineralized dentin tubules in vivo. Six green fluorescent protein-transgenic rats (body weight 100 g each) and thirty-two Sprague-Dawley (SD) male rats (body weight 250 g each) were used for DPC collection and dentin tubules preparation and transplantation, respectively. Third-passage DPCs with or without collagen gels were loaded into demineralized dentin tubules. Both types of grafts were transplanted into the rectus abdominis muscles of SD rats and were harvested after 21 days. The expression of alkaline phosphatase (ALP), bone sialoprotein (BSP), osteopontin (OPN), nestin, and dentin sialoprotein (DSP) was analyzed by immunohistochemistry. Histological analysis showed that DPCs in the collagen gel formed an osteodentin-like hard tissue matrix after 21 days. Increased positive immunoreactivity for ALP, BSP, OPN, nestin, and DSP was observed in experimental groups compared with control. Our results demonstrate that DPCs in collagen gel inside demineralized dentin tubules show increased growth and differentiation.

Clinical performance of one-piece zirconia dental implants: A systematic review.

The aim of the present review was to evaluate the clinical and radiographic performance of one-piece zirconia implants (O-PZI). This review followed the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines that addressed the following focused question: What is the overall clinical and radiographic performance of O-PZI? The MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases were searched. Six clinical studies were included. For studies evaluating O-PZI compared with one-piece titanium implants, zirconia implants showed higher crestal bone loss (CBL) in both the studies. However, one study demonstrated a high failure rate compared to titanium dental implants, while one study demonstrated comparable survival rates between zirconia and titanium dental implants. For studies evaluating O-PZI for the restoration of single crown and fixed dental prostheses, O-PZI showed comparable bone loss and survival rates for single crowns and fixed dental prostheses. Two studies were included that compared O-PZI with two-piece zirconia (T-PZI). One study showed a higher CBL and low survival rate for O-PZI compared to T-PZI, whereas the other study demonstrated comparable CBL and survival rates between O-PZI and T-PZI. It is still debatable whether O-PZI demonstrate better clinical performance when compared with titanium implants or two-piece design.

Impact of jaw location on clinical and radiological status of dental implants placed in cigarette-smokers and never-smokers: 5-year follow-up results.

PURPOSE: The aim of this 60 months follow-up investigation was to investigate the impact of jaw location on clinical and radiological status of dental-implant therapy in cigarette-smokers and never-smokers. MATERIALS AND METHODS: Twenty-nine self-reported cigarette-smokers and 27 nonsmokers were assessed. All implants were categorized into three regions with reference to their location in the maxilla or mandible: (a) Anterior zone: implants located in anterior teeth; (b) Middle zone: Implants located in the premolar region; and (c) posterior zone: implants located in the molar region. Peri-implant crestal bone loss (CBL), bleeding-on-probing (BOP) and probing-depth (PD) ≥ 4 mm and were assessed. Level of statistical significance was set at P < .05. RESULTS: Mean age of cigarette-smokers (n = 29) and never-smokers (n = 27) was 44.5 years (39-51 years) and 43.6 years (35-49 years), respectively. The average duration of cigarette-smoking was 20.3 years (17-26 years). The mean periimplant PD (P < .05) and CBL (P < .05) were significantly higher in cigarette-smokers in contrast to never-smokers in all zones. No statistically significant differences in CBL, PD, and BOP were observed in the three zones of implant location among cigarette-smokers and never-smokers. CONCLUSION: Smoking enhanced PD and CBL around dental implants and this relationship was independent of site of implant placement and jaw location.