Search

Introduction: To evaluate different factors affecting two different cohorts of dental students' perceptions with the flipped classroom (FC) model in a preclinical dental course over six years. Materials and Methods: In 2016 (cohort #1) and 2022 (cohort #2), second‐year dental students participated in FC model in a preclinical dental course consisting of pre‐class recorded videos and lectures along with classroom interactive exercises. Students then completed an anonymous pen‐and‐paper survey evaluating three factors influencing students' overall study experience with the FC model. Survey responses from cohort #1 and cohort #2 were compared to assess the effect of generation, student demographics and COVID‐19 pandemic on students' perceptions. Results: When asked to rate the FC experience out of 5, the mean ratings of cohort #1 and cohort #2 were 4.3 (±0.9) and 4.0 (±0.8), respectively. Cohort #2 preferred viewing slides and videos prior to class and had a higher agreement that pre‐class course materials were beneficial to class preparation. Conversely, cohort #1 had a higher agreement that in‐class discussion and exercises helped them to learn course content. From cohort #2, 88.6% of males and 71.6% of females preferred the FC approach over traditional lecture. Conclusion: Both cohorts reported positively with the FC model of teaching. Cohort #2 had higher positive reports with the pre‐class work and cohort #1 had a higher positive report with in‐class work. Course design should reflect the students' points of view and learning perspectives with careful consideration of the student population in the classroom. [ABSTRACT FROM AUTHOR]

Aim: The use of cannabis, which contains multiple antimicrobials, may be a risk factor for periodontitis. We hypothesized that multiple oral spirochetes would be phytocannabinoid‐resistant and that cannabidiol (CBD) would act as an environmental stressor to which Treponema denticola would respond transcriptionally, thereby providing first insights into spirochetal survival strategies. Materials and Methods: Oral spirochete growth was monitored spectrophotometrically in the presence and absence of physiologically relevant phytocannabinoid doses, the transcriptional response to phytocannabinoid exposure determined by RNAseq, specific gene activity fluxes verified using qRT‐PCR and orthologues among fully sequenced oral spirochetes identified. Results: Multiple strains of oral treponemes were resistant to CBD (0.1–10 μg/mL), while T. denticola ATCC 35405 was resistant to all phytocannabinoids tested (CBD, cannabinol [CBN], tetrahydrocannabinol [THC]). A total of 392 T. denticola ATCC 35405 genes were found to be CBD‐responsive by RNAseq. A selected subset of these genes was independently verified by qRT‐PCR. Genes found to be differentially activated by both methods included several involved in transcriptional regulation and toxin control. Suppressed genes included several involved in chemotaxis and proteolysis. Conclusions: Oral spirochetes, unlike some other periodontal bacteria, are resistant to physiological doses of phytocannabinoids. Investigation of CBD‐induced transcriptomic changes provided insight into the resistance mechanisms of this important periodontal pathogen. These findings should be considered in the context of the reported enhanced susceptibility to periodontitis in cannabis users. [ABSTRACT FROM AUTHOR]

Introduction: This study evaluated the effectiveness of a video presentation instruction compared to the prevailing traditional lecture provided in the preclinical classroom when introducing computer‐aided design/computer‐aided manufacturing (CAD/CAM) technology. Materials and Methods: This study was conducted as a controlled educational trial (single‐blind) on 120 first‐year dental students. Students were assigned to two learning groups: the control (n = 60, traditional lecture) and the intervention (n = 60, video presentation). Both groups completed a self‐efficacy scale (SES) survey before instruction. Then, the intervention group actively participated in a one‐session video presentation while the control group was given a traditional lecture. After the presentations, student knowledge was assessed with a hands‐on simulated exercise that was scored out of 60 points. At last, students completed a post‐instruction student perception and attitude (SPA) survey. Inferential hypothesis testing was conducted with two‐sample t‐tests, and significance was defined as p ≤.05. Results: There were no significant differences in the student pre‐instruction SES scores between the control and intervention groups. After the video learning, CAD/CAM knowledge application during the hands‐on simulated exercise showed significantly higher results in the intervention group as the assessment scores from the intervention group averaged 13.6 ± 2.0 points higher than the control group (p <.001). The results from the post‐instruction SPA survey showed no statistically significant difference between groups. Conclusion: With the video presentation technique, our first‐year dental students were able to greatly enhance their CAD/CAM application skills. The results from this study could be applied at other dental educational institutions with potential similar outcomes. [ABSTRACT FROM AUTHOR]

Background: Evidence on the etiology behind bone loss around submerged, prosthetically nonloaded implants is still limited. The long‐term stability and success of implants with early crestal bone loss (ECBL), especially when placed as two‐stage implants, is uncertain. Hence, the aim of this retrospective study is to analyze the potential patient‐level, tooth‐ and implant‐related factors for ECBL around osseointegrated, submerged implants, before restoration as compared with healthy implants with no bone loss. Methods: Retrospective data were collected from patient electronic health records between 2015 and 2022. Control sites included healthy implants with no bone loss and test sites included implants with ECBL, both of which were submerged. Patient, tooth and implant level data were collected. ECBL was assessed using periapical radiographs obtained during implant placement and second‐stage surgeries. Generalized estimating equation logistic regression models were used to account for multiple implants within patients. Results: The total number of implants included in the study was 200 from 120 patients. Lack of supportive periodontal therapy (SPT) was shown to have nearly five‐times higher risk of developing ECBL and was statistically significant (p < 0.05). Guided bone regeneration (GBR) procedures before implant placement had a protective effect with an odds ratio of 0.29 (p < 0.05). Conclusions: Lack of SPT was significantly associated with ECBL, while sites that received GBR procedures prior to implant placement were less likely to exhibit ECBL. Our results underscore the importance of periodontal treatment and SPT for peri‐implant health, even when the implants are submerged and unrestored. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of cleaning solutions on surface properties of 3D-printed resins., Materials and Methods: Seven different resin materials for denture base and teeth were used in the form of 280 half-disks. Samples were randomly assigned to two cleaning groups (FD, FreshDent; PO, Polydent), with daily 2- or 3-min immersion followed by water storage, repeated for 30 days. Samples were then cleaned in an ultrasonic bath with water and analyzed for surface roughness (Keyence, VHX-7000N) and hardness (Shimadzu, HMV-2 series). The pH of cleaning solutions was analyzed over 5-min and the surface morphology of specimens was analyzed via scanning electron microscopy (SEM). Statistical analysis used two-way ANOVA (α = 0.05)., Results: Surface roughness of base materials was significantly affected (p < 0.001), whereas roughness of teeth materials was not. As for hardness, there was a significant interaction between materials and cleaning solution for both, base (p < 0.001) and teeth (p < 0.001). For teeth materials, PO significantly increased Denture's (Dentca) hardness and decreased that of Rodin's (Pac Dent), while PO significantly increased Rodin's Base (Pac Dent) hardness. The hardness of Flexcera Ultra (Envision Tec), Glidewell (Glidewell), Lucitone (Dentsply Sirona), and NextDent (NextDent) teeth and base materials were not affected by the cleaning solution. Overall, the pH of FD averaged 7.3 and PO averaged 6.6. All the SEM images indicated surface irregularities after immersion in either FD or PO., Conclusions: One-month of storage and cyclic cleaning of 3D- printed resins did not affect surface roughness but had a significant impact on hardness. The cleaning solutions' effect was not homogeneous among materials., (© 2024 by the American College of Prosthodontists.)

Objectives: To assess the effect of standard filtered back projection (FBP) and iterative reconstruction (IR) methods on CBCT image noise and processing time (PT), acquired with various acquisition parameters with and without metal artefact reduction (MAR)., Methods: CBCT scans using the Midmark EIOS unit of a human mandible embedded in soft tissue equivalent material with and without the presence of an implant at mandibular first molar region were acquired at various acquisition settings (milliamperages [4mA-14mA], FOV [5 × 5, 6 × 8, 9 × 10 cm], and resolutions [low, standard, high] and reconstructed using standard FBP and IR, and with and without MAR. The processing time was recorded for each reconstruction. ImageJ was used to analyze specific axial images. Radial transaxial fiducial lines were created relative to the implant site. Standard deviations of the gray density values (image noise) were calculated at fixed distances on the fiducial lines on the buccal and lingual aspects at specific axial levels, and mean values for FBP and IR were compared using paired t-tests. Significance was defined as p < 0.05., Results: The overall mean for image noise (± SD) for FBP was 198.65 ± 55.58 and 99.84 ± 16.28 for IR. IR significantly decreased image noise compared to FBP at all acquisition parameters ( p < 0.05). Noise reduction among different scanning protocols ranged between 29.7% (5 × 5 cm FOV) and 58.1% (5mA). IR increased processing time by an average of 35.1 s., Conclusions: IR significantly reduces CBCT image noise compared to standard FBP without substantially increasing processing time.

There exist numerous programs and packages that perform validation for a given clustering solution; however, clustering algorithms fare differently as judged by different validation measures. If more than one performance measure is used to evaluate multiple clustering partitions, an optimal result is often difficult to determine by visual inspection alone. This paper introduces optCluster, an R package that uses a single function to simultaneously compare numerous clustering partitions (created by different algorithms and/or numbers of clusters) and obtain a "best" option for a given dataset. The method of weighted rank aggregation is utilized by this package to objectively aggregate various performance measure scores, thereby taking away the guesswork that often follows a visual inspection of cluster results. The optCluster package contains biological validation measures as well as clustering algorithms developed specifically for RNA sequencing data, making it a useful tool for clustering genomic data., Availability: This package is available for free through the Comprehensive R Archive Network (CRAN) at http://cran.rproject.org/web/packages/optCluster/.