Category: Nevin Manimala

Gen Dent. 2026 Jul-Aug;74(4):70-76.

ABSTRACT

Light transmission during photopolymerization is reduced by the intrinsic optical properties of ceramics, which vary with material and thickness. The higher translucency of lithium disilicate contrasts with the chemical inertness and opacity of third-generation zirconia materials, which often require dual-cure resin cements to ensure adequate polymerization. This study evaluated the influence of the thickness of lithium disilicate and monolithic zirconia ceramics on the bond strength of a universal resin cement following 24 hours and 6 months of water storage. High-translucency lithium disilicate and zirconia discs were milled in 2 thicknesses: 0.5 mm and 1.5 mm (n = 10). Cylinders of light-curing resin cement, 0.7 mm in diameter, were bonded following application of a universal adhesive system. Microshear bond strength testing and failure mode analysis were performed after 24 hours and 6 months of water storage in a temperature-controlled, light-protected environment. Mixed generalized linear models showed that the 1.5-mm zirconia group presented a higher mean bond strength (P < 0.05). The 1.5-mm zirconia group showed significantly higher mean bond strengths than the 1.5-mm lithium disilicate group at both evaluation times (P < 0.05). Both 0.5- and 1.5-mm-thick zirconia discs exhibited a statistically significant reduction in bond strength after 6 months of storage (P < 0.05), whereas lithium disilicate discs in both thicknesses maintained stable bond strengths over time (P > 0.05). The chi-square test revealed a significant association between premature failure and the material group, with no premature failures occurring in the 0.5-mm lithium disilicate group after either storage time. Although the bond strength of zirconia decreased over time, 1.5-mm-thick zirconia still attained a higher value than 1.5-mm-thick lithium disilicate at the 6-month timepoint. Lithium disilicate showed stable values at both thicknesses.

PMID:42329617

Gen Dent. 2026 Jul-Aug;74(4):65-68.

ABSTRACT

The aim of this in vitro study was to evaluate the surface roughness of microhybrid and nanohybrid composite resins subjected to polishing procedures immediately after curing or after 24 hours of immersion in distilled water. Two groups, comprising a total of 60 disc-shaped (10 × 2-mm) specimens, were prepared using microhybrid and nanohybrid composite resins (n = 30 per material) and further categorized into subgroups based on the polishing protocol. Specimens were fabricated by packing the appropriate composite resin into a cylindrical mold, compressing the material between transparent polyester film strips at both ends, and curing each side of the specimen with an LED light for 40 seconds. All specimens were finished immediately after polymerization using a 12-fluted tungsten carbide bur in a high-speed handpiece for 15 seconds under water cooling. The specimens in each material group were then divided into 2 subgroups (n = 15 each). One subgroup was polished immediately after finishing; the other was stored in distilled water at 37°C in a dark environment for 24 hours prior to polishing. Polishing was performed using a planar motion with 10 strokes at a low speed of 12,000 rpm, applying light pressure for 30 seconds. Surface roughness (R_a) was analyzed with a profilometer. Independent t tests were performed to compare the R_a data of the groups, and values of P < 0.05 were considered statistically significant. The R_a values of nanohybrid specimens were significantly lower than those of microhybrid specimens, regardless of whether polishing was performed immediately or delayed. Delayed polishing significantly reduced the R_a values of both materials. Nanohybrid composite resins demonstrated superior polishability and surface smoothness, making them a preferred choice for both immediate and delayed polishing.

PMID:42329616

Gen Dent. 2026 Jul-Aug;74(4):40-48.

ABSTRACT

This study examined the demographics, practice characteristics, service mix, and barriers faced by general and pediatric dentists in the provision of orthodontic care to the pediatric population, including children enrolled in Medicaid programs. A 31-item questionnaire was developed and distributed by email to 567 members of the Academy of Gp Orthodontics and the American Orthodontic Society. Analyses included descriptive and inferential statistical methods: chi-square, Kruskal-Wallis, and Student t tests; analysis of variance; and Spearman correlation. A value of (P < 0.05) was considered statistically significant. Thirty-four practitioners (6.0%), the majority male (58.8%), completed the survey. The mean (SD) age of respondents was 53.3 (11.8) years, and on average they had been practicing 23.3 (12.9) years. Respondents primarily practiced in suburban areas (47.1%), and most identified as general dentists (85.3%). Only 23.5% reported providing orthodontic services to children enrolled in Medicaid. The most common reasons for not participating in the program included low reimbursement rates, difficulty with billing, and patient noncompliance. Although time dedicated to orthodontic services varied, the majority (55.9%) allocated 10% to 25% of their practice time to such treatments. Most respondents (79.4%) referred cases to orthodontists, mainly Class III malocclusions (30.6%) and open bites (23.6%). General and pediatric dentists increase access to orthodontic services by evaluating patients, rendering care, and, when appropriate, referring patients to specialists. Respondents to this survey reported multiple barriers to providing orthodontic care, particularly for the Medicaid population. These findings underscore the need for reforms to address financial and administrative barriers to orthodontic care, particularly for underserved populations.

PMID:42329612

Gen Dent. 2026 Jul-Aug;74(4):34-38.

ABSTRACT

This in vitro study aimed to compare the effects of conventional and ultrasonic root canal preparation on the adhesion of glass fiber posts to root canal dentin. A total of 20 human maxillary central incisors were instrumented and then filled with gutta percha and sealant using the lateral condensation technique. The teeth were randomly divided into 2 equal groups (n = 10), gutta percha was removed, and canals were prepared using a different protocol for each group: in the conventional group, a Gates-Glidden drill, a Largo drill, and post bur kit were used; in the ultrasonic group, ultrasonic tips were operated in endo mode. Microcomputed tomography was used to confirm complete removal of the filling material, and fiber posts were cemented with self-adhesive resin cement. The apical ends of the roots were discarded, and the remaining portions were transversely sectioned into 3 segments, each 1.5 mm thick. The sections underwent push-out testing to determine bond strength, and the adhesion defects were examined with scanning electron microscopy and stereomicroscopy to determine the failure mode. Data normality was assessed using the Kolmogorov-Smirnov test, followed by analysis of variance with Tukey test for group comparisons and chi-square tests to evaluate any associations regarding failure mode. A 5% significance level was applied. Tukey tests revealed that the conventional group exhibited statistically significant lower push-out bond strengths than the ultrasonic preparation groups across all thirds; no statistically significant differences were noted among the cervical, middle, and apical thirds within the same group. There were no statistically significant differences in failure modes between the preparation groups, and adhesive failure was the most prevalent mode. The ultrasonic method effectively removed gutta percha from canals and enhanced the bond strength of fiber posts.

PMID:42329611

Gen Dent. 2026 Jul-Aug;74(4):21-26.

ABSTRACT

This study evaluated and compared the perceptions of general dentists, pediatric dentists, and orthodontists regarding the need for transverse maxillary expansion for Class I malocclusions with posterior crossbite. An electronic survey consisting of digitally manipulated intraoral images depicting 8 clinical scenarios was distributed to 10,000 general dentists, 8734 pediatric dentists, and 2400 orthodontists. A total of 566 practitioners responded (2.7% response rate): 85 general dentists, 339 pediatric dentists, and 142 orthodontists. For each case, participants assessed the need for expansion, type of expansion, and referral preferences. Statistical analyses included chi-square tests and multivariable logistic regression, which were adjusted for specialty, years of experience, and geographic region. Significant differences in perception were observed in 6 of the 8 cases (P < 0.05), primarily influenced by specialty training. Orthodontists demonstrated significantly higher odds of recommending expansion than general dentists, particularly in more complex presentations. Pediatric dentists more frequently opted for referral rather than treatment. Neither years of practice nor geographic region significantly influenced diagnostic decisions. Survey reliability demonstrated moderate to substantial agreement across repeated cases (κ = 0.424 to 0.677), and power analysis indicated sufficient sample size and effect sizes for most scenarios. These findings suggest that specialty training strongly influences the perceived need for transverse maxillary expansion, highlighting a potential need for enhanced orthodontic diagnostic education in dental and pediatric residency programs to promote consistency in the diagnosis and management of transverse discrepancies across dental specialties.

PMID:42329609

Ann Surg Oncol. 2026 Jun 22. doi: 10.1245/s10434-026-19996-1. Online ahead of print.

ABSTRACT

BACKGROUND: Esophageal cancer is associated with substantial morbidity and mortality worldwide and is frequently diagnosed at advanced stages, leading patients and their relatives to seek health-related information beyond traditional clinical encounters. In recent years, YouTube has become a popular source of medical information. Nevertheless, questions persist regarding the accuracy, credibility, and overall reliability of the content available on the platform.

METHODS: This cross-sectional study evaluated publicly available YouTube videos related to esophageal cancer. Data were collected on December 3, 2025, using a browser without a user login to minimize algorithm-driven bias. Viewer engagement metrics (views, likes, and comments), source categories, and country of origin were recorded for each video. Content quality and reliability were assessed using the DISCERN instrument, Journal of the American Medical Association (JAMA) benchmark criteria, and Global Quality Score (GQS). Non-parametric statistical analyses were used to compare quality outcomes across source categories and evaluate the correlations between the engagement metrics and quality scores.

RESULTS: A total of 78 videos met the inclusion criteria, most of which originated in the USA (83.3%). Health-related channels constituted the largest source category (35.9%), followed by patient experience-based videos (23.1%), and private institutions (20.5%). Viewer engagement metrics (views, likes, and comments) did not differ significantly among source types (p > 0.05). In contrast, the content quality varied substantially. Videos produced by public institutions achieved the highest DISCERN, JAMA, and GQS values, whereas patient-experience-based videos demonstrated significantly lower quality and reliability (p < 0.001). Engagement metrics were strongly intercorrelated but showed no association with quality scores.

CONCLUSION: YouTube videos related to esophageal cancer frequently exhibit moderate informational quality, and popularity metrics do not reflect content reliability. Source credibility plays a critical role in determining video quality, underscoring the need for greater involvement of healthcare professionals and public institutions in digital health content production.

PMID:42329563 | DOI:10.1245/s10434-026-19996-1

Oral Radiol. 2026 Jun 22. doi: 10.1007/s11282-026-00942-6. Online ahead of print.

ABSTRACT

OBJECTIVE: Pleomorphic adenoma (PA) is the most common benign parotid tumour. Magnetic resonance imaging (MRI) and fine-needle aspiration cytology (FNAC) are routinely used during preoperative work up. However, there is insufficient evidence to support the use of MRI alone to diagnose a PA. This paper aims to evaluate the diagnostic performance of MRI and FNAC in the diagnosis of PA and develop an MRI assessment tool to potentially reduce an invasive biopsy.

METHODS: A retrospective cohort study was conducted in 155 patients with histopathologically confirmed parotid tumours with preoperative MRI and/or FNAC between 2015 and 2020. Two experienced head and neck radiologists, both with over 20 years’ experience, blinded to final histopathology, evaluated 100 MRIs. Diagnostic values for detecting PA with MRI and FNAC were evaluated. An MRI assessment tool was developed based on clinical criteria and MRI characteristics typical for a PA.

RESULTS: The sensitivity, specificity, positive predictive value (PPV), negative predictive value, (NPV) and diagnostic accuracy for predicting PA were 93%, 97%, 96%, 94% and 95% (Area under ROC curve (AUC) 0.95) for FNAC and 95%, 90%, 86%, 96% and 92% (AUC 0.93) for MRI respectively. There was no statistically significant difference between MRI and FNAC for diagnosing PA with regards to sensitivity (p = 0.628), specificity (p = 0.162) or overall accuracy (p = 0.361).

CONCLUSION: MRI is a noninvasive imaging technique that can predict PA with similar sensitivity, specificity and diagnostic accuracy compared with FNAC. The PA MRI assessment tool aims to assist in surgical management decisions, while potentially reducing the need for an invasive biopsy.

PMID:42329557 | DOI:10.1007/s11282-026-00942-6

Saudi Dent J. 2026 Jun 22;38(7):91. doi: 10.1007/s44445-026-00201-8.

ABSTRACT

Endodontically treated teeth often have compromised tooth structure, which increases their susceptibility to fracture. This in vitro study compared the fracture resistance of endodontically treated mandibular premolars restored using the sandwich technique, Nayyar core composite, and semi-direct composite onlay. Seventy-six extracted mandibular premolars were randomly allocated into four groups (n = 19): intact teeth (control), conventional sandwich technique, Nayyar core composite, and semi-direct composite onlay. All groups except the control teeth group underwent standardized root canal treatment and obturation, followed by composite restoration according to the group allocation. Specimens were loaded axially in a universal testing machine until fracture. Fracture resistance was recorded in kilonewtons (kN). Data were analyzed using one-way ANOVA and Dunnett T3 post-hoc tests (p < 0.05). Mean fracture resistance was highest in the intact control group (8.70 ± 4.09 kN), followed by the sandwich technique (7.50 ± 1.55 kN), Nayyar core composite (6.10 ± 1.61 kN), and semi-direct composite onlay (4.94 ± 3.16 kN). The overall difference among the groups was statistically significant (p = 0.001). Post-hoc analysis showed significant differences between the control and semi-direct onlay groups (p = 0.019) and between the sandwich technique and semi-direct onlay groups (p = 0.022). Within the limitations of this in vitro study, the sandwich technique demonstrated the highest fracture resistance when compared with Nayyar core composite restoration and semi-direct composite onlay in endodontically treated mandibular premolars with conservative access preparation and intact marginal ridges.

PMID:42329556 | DOI:10.1007/s44445-026-00201-8

Esophagus. 2026 Jun 22. doi: 10.1007/s10388-026-01223-1. Online ahead of print.

ABSTRACT

BACKGROUND: Risk assessment is essential for planning esophagectomy in patients with esophageal or gastro-esophageal junction (GEJ) cancers. However, previous reports using only preoperative variables (preoperative risk models) have poorly predicted postoperative anastomotic leakage. This study aimed to develop a novel risk model for anastomotic leakage using a combination of preoperative, intraoperative, and postoperative variables (perioperative risk model).

METHODS: Clinical data of 20,113 patients with esophageal or GEJ cancer who underwent esophagectomy followed by reconstruction between 2016 and 2019 were retrieved from the National Clinical Database (NCD), a Japanese web-based nationwide registry. Preoperative and perioperative risk models for anastomotic leakage were developed using only preoperative variable and a combination of preoperative, intraoperative, and postoperative variables within 72 h, respectively. The performance of the perioperative risk model was validated using NCD data of 5,147 esophagectomies registered in 2020.

RESULTS: In the overall population, 11,360 (45.0%) patients were aged ≥ 75 years, and 81.3% were male. Preoperative variables were comparable between the development and external validation cohorts. Anastomotic leakage was observed in 13.7% and 14.4% of the development and validation cohorts, respectively, and in 13.9% of all patients. The optimism-corrected C-statistics was higher in the perioperative risk model (0.610; 95% CI, 0.599-0.621) than in the preoperative risk model (0.565; 95% CI, 0.554-0.577). In the validation analysis, the C-statistics was 0.602 (95% CI, 0.580-0.623) for predicting anastomotic leakage.

CONCLUSION: Postoperative risk assessment using perioperative variables, including operative factors and early postoperative events, may help surgeons predict anastomotic leakage and improve patient management after esophagectomy.

PMID:42329555 | DOI:10.1007/s10388-026-01223-1

J Cardiovasc Transl Res. 2026 Jun 22;19(1):75. doi: 10.1007/s12265-026-10804-5.

ABSTRACT

Left ventricular thrombus (LVT) in ischemic heart failure carries embolic risk; tools to anticipate persistence are limited. We studied 190 consecutive patients with imaging-confirmed LVT managed with guideline-concordant anticoagulation and serial echocardiography. The primary outcome was 6-month non-regression; 1-year MACE was secondary. We combined classical statistics with explainable machine learning. CatBoost yielded the best discrimination for non-regression (CV-AUC 0.76; test accuracy 0.79). SHAP highlighted left atrial diameter, pulmonary artery pressure, platelet count, and LV end-diastolic diameter as leading predictors. For 1-year outcomes, thrombus size and CHA2DS2-VA were independently associated with MACE (logistic AUC 0.71), whereas “regression vs persistence” alone was not. Baseline remodeling and coagulability markers, captured by an interpretable ML model, stratify early risk of LVT persistence and complement clinical decision-making for imaging follow-up and anticoagulation intensity.

PMID:42329547 | DOI:10.1007/s12265-026-10804-5