Assessment of Stress Distribution Around Dental Implants Based on the All-on-Four Treatment Concept using Finite Element Analysis.

The present study was conducted to assess stress distribution around dental implants based on the all-on-four treatment concept. The finite element analysis (FEA) models comprised cancellous bone covered with cortical bone. Four dental implants were placed in two different designs. In model 1, the four implants were placed parallel to each other, whereas, in model 2, the all-on-four concept was followed. The vertical and lateral loads of various values were applied, and stress was evaluated. In model 2, the least stress was observed in both lateral and vertical loading in the peri-implant region. The all-on-four concept proved to be beneficial in reducing the stress around dental implants, thereby reducing the treatment cost.

Micro Tensile bond strength and microleakage assessment of total-etch and self-etch adhesive bonded to carious affected dentin disinfected with Chlorhexidine, Curcumin, and Malachite green.

AIMS AND OBJECTIVES: Assessment of micro tensile bond strength (microTBS) and micro-leakage scores of total-etch adhesive (TAE) and self-etch adhesive (SAE) bonded to carious affected dentin (CAD) sterilized using different cavity disinfectant (curcumin photosensitizer (CP) and malachite green (MG) and Chlorhexidine (CHX) in comparison to no disinfection (ND) control group. MATERIALS AND METHODS: One hundred and twenty human molars having International Caries Detection and Assessment System (ICDAS) scores of 4 and 5 were included. Visual inspection, dental explorer hardness testing, and caries detector solution using 5% basic Fuchsin dye solution was applied to dentin to identify the CAD surface. All the specimens were divided into four groups (n = 30) according to the cavity disinfectants used. Group A: 2% CHX, Group B: CP, Group C: MG, and Group D: ND. Each group was further divided into two subgroups (n = 15) based on the adhesion protocol. Groups A1, B1, C1, and D1 were held using TEA, and groups A2, B2, C2, and D2 were adhered using SEA system. The composite material was then built in 2 mm increments and then cured with light. MicroTBS and failure mode assessment using a universal testing machine (UTM) and stereomicroscope at a 40X magnification was performed on 10 samples from each subgroup. The microleakage assessment was performed using a dye penetration test on five samples from each group. ANOVA and Tukey post-hoc tests were used to compare means and standard deviation (SD) of bond strength and microleakage (p < 0.05). RESULTS The maximum microTBS was displayed by A1= CHX and TEA (13.28± 1.01 MPa). The lowest bond scores were demonstrated by C2= MG and SEA (5.98±0.44 MPa). The highest micro-leakage was exhibited by C1= MG and TEA (58.32 ± 2.11 nm). Whereas, the lowest micro-leakage values were displayed by A2= CHX and SEA (24.34± 1.11 nm). CONCLUSION: Chlorohexidiene displayed better bond strength and the lowest microleakage scores with Total-etch adhesive and Self-etch adhesives when used as a cavity disinfectant. Total-etch adhesives performed better in terms of microTBS scores whereas self-etch adhesives displayed superior seal ability within the same disinfectant group.

Use of final irrigants MTAD, Salvedora Perscia, Malachite green, and Ti-sapphire laser on push-out bond strength of Zirconia post.

AIM: Evaluation of the push-out bond strength (PBS) of zirconia post-bonded to radicular dentin after using different final irrigants (MTAD, Malachite green (MG), Ti-sapphire laser and Salvadora persica (S.persica). MATERIAL AND METHOD: Forty human permanent single-rooted were decoronated above the cement-enamel junction. An experienced endodontist performed all the root canal instrumentation using ProTaper universal rotary files. Canals were irrigated using 5.25% NaOCl solution followed by EDTA as a final sterilant. Obturation with gutta-percha using AH Plus sealer was performed. Post-space preparation was completed using Gates Glidden and specimens were randomly assigned to four groups based on the final disinfectant received (n=10). Group 1: 5.25% NaOCl + MTAD, group 2: 5.25% NaOCl + MG, group 3: 5.25% NaOCl +Ti-sapphire laser, and group 4: 5.25% NaOCl + S. persica. The chemically polymerized resin was used to lute zirconia posts. PBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40X magnification. Data were compared between the two groups with 95% CI using one-way analysis of variance (ANOVA) with the Tukey post hoc test. p=0.05. RESULTS: Group4(5.25% NaOCl+ S.persica) specimens demonstrated the maximum (8.94±0.14 MPa) bond strength. Conversely, the apical third of Group 2 (5.25% NaOCl+ MG) (2.87±0.15 MPa) samples revealed the minimum bond strength scores. Intergroup comparison exposed that Group 1 (1.3% NaOCl+ MTAD), Group 3 (5.25% NaOCl+Ti-sapphire laser), and Group 4 (5.25% NaOCl+ S. persica) at all three-thirds unveiled no significant difference in PBS (p<0.05). CONCLUSION: Ti-sapphire laser and Salvedora Persica possess the potential to be used as a final root canal irrigant to improve the push-out bond strength of zirconia post-to-root dentin.

Impact of lockdown and COVID-19 on the learning status of postgraduate students during the pandemic in India: A questionnaire-based study.

Observations have suggested that during the coronavirus disease 2019 pandemic, because of lockdown students who are in process of doing their thesis related work exhibit responses related to stress due to the fear of spread contagion and because of various limitations in performing thesis work, especially patient-oriented collection of data and clinical work. The present study aimed to determine various problems faced by the students in postgraduate courses for completing their thesis during pandemic. This was a prospective and cross-sectional study based on a questionnaire. This study was comprised of a total sample size of 300 postgraduate students of different disciplines in the health stream. The study was conducted between June 2021 and December 2021. The prepared study questionnaire was sent to postgraduates by use of electronic mail. Of the total selected students, 280 had responded with complete answers to the questionnaire. Collected data were entered into a Microsoft Excel sheet and analyzed for percentage distribution. 50.7% of postgraduates were found in the age range of 26-30 years, 73.1% were female and 35.6% were in their final year of postgraduation. It was seen that 6.5% were unable to procure ethical approval due to the pandemic, and 43.1% were not able to get permission from the board due to the sudden pandemic. 64.9% were unable to collect data for their thesis, and 18% were unable to report to supervisors. 86.9% of postgraduates suffered from anxiety due to the inability to perform thesis work. 78.9% of postgraduate students had a decrease in motivation for a thesis and 89.1% suffered from anxiety. Due to the ongoing pandemic, postgraduate students are facing many problems in completing their thesis work. This resulted in anxiety and stress themselves.

Glass fiber post resistance to dislodgement from radicular dentin after using contemporary and conventional methods of disinfection.

AIM: The present study aimed to assess the bond integrity of curcumin photosensitizer (CPS) Photodynamic therapy (PDT) on fiber post disinfection bonded to radicular dentin in comparison to the conventional fiber post sterilant used. MATERIALS AND METHODS: Fifty human permanent single-rooted premolars were utilized with the crown part sectioned using up to the cementoenamel junction. Root canal preparation was performed followed by canal obturation with gutta-percha (GP) and resin-based sealer. The post space was prepared using peso reamers leaving 4 mm at the apical part of the post space. Fifty glass fiber posts (GFP) were divided into five groups based on the surface disinfectant (n = 10). group 1: Autoclave sterilization (AS) group 2: chlorhexidine digluconate (CHX dig), group 3: CPS solution, group 4: 35% phosphoric acid (PA) gel, and group 5: No disinfection. Cementation was performed using dual-cure self-etch resin cement. Each tooth was sectioned and placed on the universal testing machine. Failure mode was analyzed using a stereomicroscope at 40x magnification. Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey multiple comparison tests. (p = 0.05). RESULTS: Intragroup comparison analysis demonstrated that group 2 in which 2% CHX dig was used as a post-surface disinfectant revealed the highest bond integrity at all three levels. Group 5 where no disinfectant was used to decontaminate the post surface exhibited the lowest bond values. In all the investigated groups, PBS values showed a downward trend from coronal to the apical third of the post space. Group 1 in which AS was used to sterilize the fiber post and group 3 in which CPS was smeared to decontaminate the GFPs surface-displayed comparable outcomes of PBS to group 5 specimens at all three levels. (p > 0.05). CONCLUSION: CHX dig and PA post-surface disinfection displayed a positive impact on bond strength with the radicular dentin. However, CPS and AS do not reveal any effect on the PBS when used for post-decontamination.

Noncarious cervical lesion pretreated using antimicrobial photodynamic therapy and diode laser in reducing dentin hypersensitivity bonded to different restorative material: Valuation of bond values and invitro dye leakage.

AIM: The present study aimed to appraise the effect of Diode laser (DL), riboflavin, and curcumin on the bond strength of adhesive restorative material and the effects of pretreatment on microleakage scores. MATERIAL AND METHODS: Ninety caries-free human permanent premolars were obtained and disinfected. All specimens were mounted till CEJ. To provide standardization, a 2 × 2 mm flat non-carious cervical lesion (NCCL) dentin surface was exposed. This was followed by dentin surface roughening/cervical groove preparation with a round bur. After tooth surface preparation, ninety specimens were divided arbitrarily into three groups. Group 1: NCCL exposed to DL; group 2: NCCL pretreated with riboflavin photosensitizer (RFP) and group 3 pretreated with curcumin photosensitizer (CP). All the three groups were further divided into two subgroups A1, A2, B1, B2, C1, and C2 based on the restorative material used (n = 15). Subgroup A1, B1, and C1 were restored with composite resin (CR). Subgroup A2, B2, and C2 were restored with RMGIC. Ten samples from each subgroup were evaluated for shear bond strength (SBS) testing under a universal testing machine (UTM). Five from each subgroup were evaluated for microleakage assessment. Bond strength and microleakage analysis were performed using analysis of variance (ANOVA) with a Post-hoc test (Tukey's post hoc test) at a significance level (p = 0.05). RESULTS: The group A1, DL-CR shows the highest SBS (16.41± 0.4 MPa). However, CP-RMGIC groups demonstrated the lowest bond integrity. RFP-CR and the DL-CR group displayed comparable outcomes of SBS (p>0.05). The highest microleakage was observed with CP-RMGIC. The least microleakage was displayed by DL-CR. CONCLUSION: Noncarious cervical lesions pretreated with diode laser and riboflavin photosensitizer showed better shear bond strength and reduced microleakage when bonded to composite resin than non-carious cervical lesions pretreated with curcumin.

Comparison of the Solubility of Conventional Luting Cements with that of the Polyacid Modified Composite Luting Cement and Resin-modified Glass lonomer Cement.

INTRODUCTION: This study was planned to find the solubility of the conventional luting cements in comparison with that of the polyacid-modified composite luting cement and recently introduced resin-modified glass ionomer cement (RMGIC) with exposure to water at early stages of mixing. MATERIALS AND METHODS: An in vitro study of the solubility of the following five commercially available luting cements, viz., glass ionomer cement (GIC) (Fuji I, GC), zinc phosphate (Elite 100, GC), polyacid-modified resin cement (PMCR) (Principle, Dentsply), polycarboxylate cement (PC) (Poly - F, Dentsply), RMGIC (Vitremer, 3M), was conducted. For each of these groups of cements, three resin holders were prepared containing two circular cavities of 5 mm diameter and 2 mm depth. All the cements to be studied were mixed in 30 seconds and then placed in the prepared cavities in the resin cement holder for 30 seconds. RESULTS: From all of the observed luting cements, PMCR cement had shown the lowest mean loss of substance at all immersion times and RMGIC showed the highest mean loss of substanceat all immersion times in water from 2 to 8 minutes. The solubility of cements decreased by 38% for GIC, 33% for ZnPO4, 50% for PMCR, 29% for PC, and 17% for RMGIC. CONCLUSION: The PMCR cement (Principle-Dentsply) had shown lowest solubility to water at the given time intervals of immersion. This was followed by PC, zinc phosphate, and GIC to various time intervals of immersion.