Utilization of 3D evaluation for assessing selective caries removal practice in pre-clinical dental students: a pilot study.

BACKGROUND: Practicing and assessment of selective caries removal techniques in dental students remain challenges in many dental schools. The aim of this study was to utilize a 3D assessment technique, within a designated acceptable range of deviation, to evaluate the tendency of dental students in performing selective caries removal (SCR). The correlation between 3D assessment results and the conventional rubric rated by an instructor was also determined. METHODS: Fifth-year dental students (n = 61) performed the SCR task on 3D-printed teeth containing simulated deep caries lesions in occlusal and proximal surfaces. One instructor assessed the results using a conventional analytic rubric. The excavated teeth were additionally evaluated using 3D analysis software with the designated acceptable range of deviations (± 0.5 mm) from the standard cavities. The average root mean square (RMS) value, representing the deviation between student-prepared cavities and the predefined standard cavities, was recorded. A tendency towards over-excavation was defined for RMS values > 0.5 mm, and towards under-excavation for RMS values < 0.5 mm. RESULTS: The mean (min-max) of RMS was 0.27 (0.18-0.40) for occlusal and 0.29 (0.20-0.57)for proximal cavities. A tendency of dental students toward over-excavation was observed in both occlusal (74%) and proximal cavities (87%). There was a moderate negative correlation between the RMS values and the traditional rubric scores for both occlusal (R2 = 0.148, P = 0.002) and proximal cavities (R2 = 0.107, P = 0.010). CONCLUSIONS: The 3D evaluation technique effectively revealed specific tendencies in dental students' caries removal skills. The integration of computerized assessments with traditional methods could potentially assist the instructors in delivering more objective and specific feedback to students. Further research is encouraged to investigate the impact of this assessment technique on improving student performance in selective caries removal skills.

Survival of Four Conical Implant Abutment Connections After Removal of the Abutment Screw and Simulated Cyclic Loading: An In Vitro Comparative Study.

This in vitro study evaluated the mechanical behavior of different conical connection implant systems after abutment screw withdrawal. Four conical connection systems were selected based on different conical half-angles: Ankylos (5.7°), Cowell (7.0°), Straumann (7.5°), and Astra (11.0°). In each system, 5 implants and abutments were used (n = 5). According to the recommended value, each abutment screw was torqued to settle the abutment and then withdrawn through a predesigned hole of the cemented crown. The retentiveness of the abutment was evaluated by the following mechanical testing. All specimens were subjected to cyclic loading of 20-200 N, 30°, and 4-mm off-axis to the implant axis, for 106 cycles. The pullout forces and axial displacements of the abutments were measured. The data of the Cowell system was obtained from our previous work. All groups other than Astra group, in which abutment loosened after abutment screw withdrawal, passed the cyclic loading test. Straumann group demonstrated a significantly lower pullout force (27.4 ± 21.1 N) than Ankylos (160.1 ± 41.4 N) and Cowell (183.7 ± 30.5 N) groups. All groups showed abutment rebound after screw withdrawal except Straumann group. In addition, Ankylos, Cowell, and Straumann groups demonstrated axial displacement after cyclic loading. In terms of the retentiveness of the abutment after abutment screw withdrawal examined in this study, Ankylos and Cowell groups had much higher retentiveness than Straumann group, while Astra group had none. Conical angle could be a key design parameter to make abutment screw withdrawal after conical abutment settlement feasible, but more studies must be conducted for clinical application.

Effects of core buildup composite resin translucency on intraoral scanner accuracy: an in vitro study.

AIM: The accuracy of 3D images produced by an intraoral scanner (IOS) is affected by the optical characteristics of restorative materials such as metal, ceramic, and composite resin. The present in vitro study aimed to investigate the impact of core buildup composite resin translucency on IOS accuracy. MATERIALS AND METHODS: A core buildup procedure was performed on a proprietary 3D-printed model using injectable composite resins in four groups with different levels of translucency (highest to lowest: AE, A3, AO3, and EX). Ten experimental scans per group were performed using a Medit i700 IOS on a phantom head-mounted model. Reference scans were obtained using an industrial scanner (Solutionix C500). Values of accuracy (trueness and precision) for the respective groups were evaluated using mean deviation values following 3D superimposition. RESULTS: Composite resin translucency caused the scale reduction of the optical impressions. Values of trueness showed the highest scale reduction in AE, significantly, followed by A3, AO3, and EX. Considering 50 µm as the cut-off value of deviations for clinical acceptability, the analysis showed most deviations in AE and A3. Similar results were found with precision, where AE showed the highest deviation value statistically, followed by A3, AO3, and EX. CONCLUSIONS: Composite resin translucency affects the accuracy of optical impressions, causing a fitting error of CAD/CAM prostheses. The more translucent the composite resin, the less accurate the optical impression. This suggests the need for proper compensation during prosthesis designing for an optimal clinical result. In addition, practitioners should indicate in the digital workflow the proper restorative materials regarding not only the mechanical properties and esthetics, but also the optical characteristics.

Abutment screw withdrawal after conical abutment settlement: A pilot study.

OBJECTIVE: This study investigated the effects of abutment screw withdrawal after conical abutment settlement on the stability of the implant-abutment connection. MATERIALS AND METHODS: Twenty implants of a conical connection system were used. Two two-piece abutment designs were used: cone only (n = 10; NI) and cone plus octagonal index design (n = 10; I); for each design, five samples were used with (S) and without (NS) abutment screw withdrawal before a cyclic test. Finally, four groups, namely Gr S(NI), Gr S(I), Gr NS(NI), and Gr NS(I), were included. The cyclic test included cyclic loading of 20-200 N, 30°, and 4-mm off-axis to implant axis at 10 Hz for 106 cycles, simulating a clinical time interval of 40 months. The fatigue cycles were recorded. The axial displacement of the conical abutments during abutment settlement, screw withdrawal, and cyclic loading were measured. Abutment morphology was examined through scanning electron microscopy (SEM). RESULTS: Only Gr NS(NI) failed the test, indicating that without the index design and abutment screw withdrawal, and connection stability seriously deteriorated. Gr NS(I) exhibited significantly higher axial displacement into the implant after abutment settlement than did Gr NS(NI). It also exhibited continuous axial displacement into the implant after cyclic loading. SEM after cyclic testing in Gr NS(I) revealed marked burnishing on lateral edges of the index, indicating that the index design provides an antitorsional ability. CONCLUSION: Although this study has few limitations, abutment screw withdrawal is feasible in this conical implant-abutment connection system with index design.

Stress and its association with academic performance among dental undergraduate students in Fujian, China: a cross-sectional online questionnaire survey.

BACKGROUND: The aim of this study was to investigate the amount and sources of stress in dental undergraduate students in Fujian, China, and the factors associated with stress. METHODS: This cross-sectional study was conducted during the second semester of the 2017-2018 academic year at the School of Stomatology, Fujian Medical University, China. A total of 396 students were surveyed with the Dental Environment Stress Questionnaire (DES) and the Perceived Stress Scale (PSS) using an online survey system. The participants' demographic information, including sex, age, year of study, and grade point average (GPA) was also collected. One-way analysis of variance (ANOVA) was performed to compare the stress scores. Pearson correlation and multiple linear regression analyses were conducted to explore the associated factors of stress and academic performance. All statistical analyses were performed at a significance level of 5%. RESULTS: A total of 347 undergraduate students participated in the present study, for a response rate of 87.6%. There were no significant differences in the DES and PSS total scores among students of different grades and sexes. Significant differences were found in the DES "workload" and "self-efficacy beliefs" scores among students from different study years (all P < 0.05). The Multiple linear regression showed that DES and PSS scores were negatively correlated with GPA, while sex was positively correlated with GPA (all P < 0.05). Female students had significantly higher GPAs than male students. CONCLUSIONS: Dental undergraduates in Fujian, China experienced moderate levels of stress. While the amount of stress did not differ by year of study, the sources of stress did differ. Stress scores and sex were negatively correlated with academic performance.

Correlation of magnetic resonance imaging grades with cytokine levels of synovial fluid of patients with temporomandibular joint disorders: a cross-sectional study.

OBJECTIVES: Magnetic resonance imaging (MRI) is a standardized method for assisting joint diagnosis. To validate the reliability of different imaging-based grading systems, this study examined (1) the associations between grading systems for osseous change, joint effusion, and the Wilkes classification of temporomandibular joint (TMJ) disorders and (2) the correlation between cytokines in synovial fluid and imaging-based joint scores. MATERIALS AND METHODS: Twenty-seven patients, who routinely received numeric rating scale (NRS) and MRI assessment before TMJ arthrocentesis, were enrolled. Each joint was evaluated through the grading criteria for severity of osseous change and joint effusion by blinded observers using MRI. ImageJ was employed for classifying joint effusion. Joint synovial fluid, collected through arthrocentesis, was examined for cytokine expression by using a Luminex multiplex assay. All data were analyzed using the Pearson correlation analysis. RESULTS: The Wilkes classification was strongly correlated with osseous change scores, but not with joint effusion scores. Joint effusion scores significantly correlated with NRS scores, but not with the Wilkes classification and osseous change scores. Compared with osseous change scores, joint effusion scores had a higher correlation with the levels of inflammatory cytokines (interleukin (IL)-8 and soluble IL-6 receptor (sIL-6R)) and with anti-inflammatory cytokines (soluble tumor necrosis factor receptors I and II (sTNF-RI/II)). CONCLUSIONS: In patients with TMJ disorders, MRI grades are strongly correlated with NRS scores and levels of cytokines (IL-8, sIL-6R, and sTNF-RI/II) in the synovial fluid. CLINICAL RELEVANCE: Joint effusion scoring can be a reliable and valid indicator for pathological assessment of TMJ disorders.

Correction to: Osteogenic prospective of deriving human dental stem cells in collagen matrix boost.

The original version of this article unfortunately contained a mistake. The country was incorrect in the authors affiliations. It should read as "ROC". The corrected affiliations are given below.

Osteogenic prospective of deriving human dental stem cells in collagen matrix boost.

Stem cells derived from oral tissue represent a highly attractive alternative source for clinical bone regeneration because they can be collected by non-invasive or minimally invasive procedures. Herein, we describe the human dental stem cells (DSCs) deriving from buccal fat pads (BFP), dental pulp (DP) of impacted teeth, and periodontal ligaments (PDL) to obtain BFPSCs, DPSCs, and PDLSCs, respectively. Cells were purified with selected medium and expanded through passages in stem cell culture medium. Purified cells were characterized for stemness by their growth rate, immunostaining, and multilineage differentiation ability. They showed plastic adherence, expression of stemness-specific markers, and multilineage differentiation potential. Immunocytochemistry analysis confirmed that DPSCs had more osteogenic potential than BFSCs and PDLSCs. Calcium-rich deposits, evaluated by von Kossa and Alizarin red staining, showed greater mineralization when DPSCs were cultured on collagen type I matrix than without collagen. Furthermore, DPSC-seeded collagen type I matrix maintained consistent osteogenesis and boosted mineral formation by 1-2 weeks over that in DPSCs cultured without collagen. Radiographic analysis of DPSC-seeded collagen type I matrix transplanted into rat cranial defects showed significant bone regeneration after 8 weeks. These results suggested that the redundant oral tissue can be used as a source of adult multipotent stem cells for clinical bone regeneration. Triple overlay images with biomarkers (red), nuclei (blue) and bright field morphology of DPSCs. The specifically osteo-differentiation shown by osteocalcin (left) expression and lack of sox9 (right) expressed in the images below which were cultured with collagen matrix, contrast with no collagen matrix group above.

Heat Generation on Implant Surface During Abutment Preparation at Different Elapsed Time Intervals.

PURPOSE: The purpose of this study was to evaluate heat generation at the implant surface caused by abutment preparation using a diamond bur in a high-speed dental turbine in vitro at 2 different water-coolant temperatures. MATERIALS AND METHODS: Thirty-two titanium-alloy abutments were connected to a titanium-alloy implant embedded in an acrylic resin placed within a water bath at a controlled temperature of 37°C. The specimens were equally distributed into 2 groups (16 each). Group 1: the temperature was maintained at 20 ± 1°C; and group 2: the temperature was maintained at 32 ± 1°C. Each abutment was prepared in the axial plane for 1 minute and in the occlusal plane for 1 minute. The temperature of the heat generated from abutment preparation was recorded and measured at 3 distinct time intervals. RESULTS: Water-coolant temperature (20°C vs 32°C) had a statistically significant effect on the implant's temperature change during preparation of the abutment (P < 0.0001). CONCLUSION: The use of water-coolant temperature of 20 ± 1°C during preparation of the implant abutment decreased the temperature recorded at the implant surface to 34.46°C, whereas the coolant temperature of 32 ± 1°C increased the implant surface temperature to 40.94°C.

Effectiveness of mobile augmented reality-integrated oral health education for community-dwelling older adults: A randomized controlled trial.

BACKGROUND & PURPOSE: Oral health education helps older adults optimize their oral health. However, traditional lecture-based oral health education has limitations, exacerbated by the COVID-19 pandemic. Mobile augmented reality (MAR) has emerged as an alternative educational method. This study compared the effectiveness of MAR-integrated oral health education with that of lecture-based education and no education. METHODS: This parallel, randomized controlled, open-label trial enrolled 75 older adults from six activity centers. The participants were randomly assigned, by a random number table technique, to the lecture-based, MAR, or control group. Data on oral healthcare-related knowledge, self-efficacy, and oral health status were collected through questionnaires and oral examinations at baseline, immediately after the intervention, and at a 2-week follow-up. The MAR system's usability was assessed. Statistical analyses, comprising descriptive statistics and inferential tests, were performed. RESULTS: Data from 61 participants were analyzed, 22 in the lecture-based group, 20 in the MAR group, and 19 in the control group. Both lectures and MAR education significantly improved oral health status. However, changes in knowledge and self-efficacy scores were significantly different only for the MAR versus control group (p = .002 and .001, respectively). The MAR group demonstrated better knowledge and self-efficacy retention than did the lecture-based group, without significant difference. Usability assessment revealed potential for improvement in the MAR system. CONCLUSIONS: MAR-integrated oral health education enhanced the knowledge, self-efficacy, and oral health status of community-dwelling older adults. However, addressing technology adoption and usability challenges is vital. Longer-term evaluations and broader geographical studies are recommended.

Temporal stability of tongue microbiota in older patients - A pilot study.

Background/purpose: Healthy states of human microbiota depend on a stable community of symbiotic microbes irrespective of external challenges from the environment. Thus, long-term stability of the oral microbiota is of importance, particularly for older patient populations. Materials and methods: We used next-generation sequencing (NGS) to examine the tongue microbiota of 18 individuals receiving long-term care over a 10-month period. Results: Beta diversity analysis demonstrated temporal stability of the tongue microbiota, as microbial compositions from all time points were indistinguishable from each other (P = 0.0887). However, significant individual variation in microbial composition (P = 0.0001) was observed, underscoring the presence of a unique microbial profile for each patient. Conclusion: The temporal dynamics of tongue microbiota exhibit long-term stability, providing diagnostic implications for oral diseases within older patient populations.

Effect of cutting flute design features on primary stability of immediate implant placement and restoration: a dynamic experimental analysis.

Self-tapping implants with self-cutting flutes may influence primary stability, especially for the immediate implant placement and restoration protocol in which implants are affixed to the bone in the apical portion. Screw geometry differs between brands, and the effect of apical design on its clinical outcomes remains unclear. This study is aimed at investigating the influence of cutting flute shape (spiral, straight, and without flute) on primary stability by using a dynamic experimental test. Six types of dental implants were designed using computer-aided design and computer-aided manufacturing technology, consisting of three types of cutting flute shapes along with two types of screw features. A dynamic mechanical test was performed using a cyclic loading scheme. The mechanical behaviors of resistance to lateral load (RLL), maximum force, and energy dissipation were compared between groups. In the dynamic test, implants without cutting flute also exhibited higher values in RLL, maximum force, and energy dissipation. The aggressive thread implant with straight flute displayed higher RLL and had a significantly higher values in RLL (p = 0.033) at the threshold point of bone-implant interface breakdown. The implants without cutting flutes exhibited higher primary stability. Straight flute design would improve RLL for aggressive thread implant.

A mobile augmented reality-integrated oral health education for community dwelling older adults: A pilot study.

Background/purpose: Providing oral healthcare education can be an optimal strategy for imparting knowledge and developing self-care skills for older adults to enhance their oral health conditions. However, traditional passive lecture-based education programs have several limitations. Integrating mobile augmented reality (MAR) into oral health education can potentially enhance the effectiveness of the education by mitigating those limitations. The objectives of this study are to develop and evaluate the effectiveness of MAR-integrated oral health education. The objectives of this study were to develop and evaluate the effectiveness of MAR-integrated oral health education. Materials and methods: Twenty-four older adults from community dwellings participated in this study. The participants received MAR-integrated oral health education once at activity centers. Self-report questionnaires were utilized to assess oral healthcare-related knowledge and self-efficacy, and the usability score of the MAR system. The assessment was conducted before and after the educational program. Data were statistically analyzed using descriptive statistics and paired-t test. Results: The mean scores of oral healthcare-related knowledge and self-efficacy showed a significant increase after the educational program, with P-values of <0.001 and 0.002, respectively. A majority of the participants exhibited a lack of knowledge and self-efficacy regarding the proper selection of toothpaste and interdental brushes. However, there was an improvement after the intervention. The usability score of the system was lower than the average level. Conclusion: MAR-integrated oral health education effectively increases oral health-related knowledge and self-efficacy among community dwelling older adults. Still, the usability of the MAR system needs to be improved. Further investigation of long-term effects and clinical outcomes, and the inclusion of comparative groups are recommended for the future study.

Developing and assessing the efficiency of VOSER software in recording dental caries according to WHO's criteria 2013.

Background/purpose: World Health Organization (WHO) oral health survey manual is the main guideline for most oral health surveys worldwide. It has been updated several times since 1971; however, using papers and pens for data recording remains unchanged. This study aimed to develop the Vietnam Oral Survey Electronics Recorder (VOSER) to record dental caries data based on the WHO 2013 criteria and assess its reliability and efficiency. Materials and methods: VOSER was developed and tested for reliability and efficiency by performing clinical examinations on 365 school children in three key indicator age groups: 120 5-year-old students with primary dentition, 123 8-year-old students with mixed dentition, and 122 12-year-old students with permanent dentition. One gold standard examiner and two trained clerks examined these children using either WHO's paper survey form or VOSER's digital form for dental caries. Recording time, spreadsheet time, DMFT/S, and dmft/s were analyzed to compare the efficiency of VOSER to the paper form. Cohen's Kappa, intraclass correlation coefficient, and Wilcoxon signed-rank test were adopted in the data analyses. Results: Median time of using VOSER was significantly shorter than the standard time in all three dentitions (P < 0.001). Cohen's Kappa values between data collected by VOSER and paper form showed almost perfect agreements (0.927-0.958). DMFT/S and dmft/s values calculated from data collected by both methods had good to excellent reliabilities (0.791-0.997). Conclusion: VOSER is efficient and reliable for conducting dental caries surveys according to the WHO 2013 criteria and should be utilized in the era of digital technology.

Effects of food hardness on temporomandibular joint osteoarthritis: Qualitative and quantitative micro-CT analysis of rats in vivo.

BACKGROUND: Temporomandibular joint osteoarthritis (TMJ-OA) is a degenerative joint disease in which quantitative analysis based on magnetic resonance image (MRI) or cone-beam computed tomography (CBCT) remains limited. Moreover, the long-term effects of soft food on the adaptive condylar remodeling process in TMJ-OA remain unclear. This study aimed to assess the effects of food hardness on adaptive condylar remodeling in a healthy TMJ, TMJ-OA, and controlled TMJ-OA. METHODS: Complete Freund's adjuvant (CFA) was used for TMJ-OA induction and Link-N (LN) for TMJ repair. Eighteen mature rats were randomly divided into six groups: (1) control/normal diet (Ctrl-N); (2) control/soft diet (Ctrl-S); (3) TMJ-OA/normal diet (CFA-N); (4) TMJ-OA/soft diet (CFA-S); (5) Link-N-controlled TMJ-OA/normal diet (LN-N); and (6) Link-N-controlled TMJ-OA/soft diet (LN-S). Micro-CT was performed 14, 21, and 28 days after CFA injection to analyze the bone volume, bone volume fraction (BVF), bone mineral density (BMD), and trabecular bone number and thickness (Tb.N, Tb.Th). MRI and histological imaging were performed to support the analysis. RESULTS: Under CFA treatment, the BVF and BMD decreased significantly (p < 0.01) and later recovered to normal. However, more significant improvements occurred in normal-diet groups than soft-diet groups. Additionally, bone volume changes were more predictable in the normal-diet groups than in the soft-diet groups. The normal-diet groups presented a significant decrease and increase in the Tb.N and Tb.Th, respectively (p < 0.05), while the Tb.N and Tb.Th in the soft-diet groups remained largely unchanged. Furthermore, a significantly higher frequency of irregularities on the condylar articular surface was found in the soft-diet groups. CONCLUSIONS: Compared with a soft diet, a normal diet may be beneficial for preserving condyle articular surface and directing bone remodeling in TMJ-OA rats.

Profiles of oral microbiome associated with nasogastric tube feeding.

Background: Dysbiosis of oral microbiome causes chronic diseases including dental caries and periodontitis, which frequently affect older patient populations. Severely disabled individuals with impaired swallowing functions may require nutritional supply via nasogastric (NG) tubes, further impacting their oral condition and possibly microbial composition. However, little is known about the effect of NG tube on oral microbes and its potential ramification. Methods: By using 16S rRNA amplicon sequencing, we characterized the tongue microbiome of 27 patients fed with NG tubes and 26 others fed orally. Results: The microbial compositions of NG-tube and oral-feeding patients were substantially different, with more Gram-negative aerobes enriched in the presence of NG tube. Specifically, NG-tube patients presented more opportunistic pathogens like Pseudomonas and Corynebacterium associated with pneumonia and lower levels of commensal Streptococcus and Veillonella. Co-occurrence analysis further showed an inverse relationship between commensal and pathogenic species. Conclusion: We present a systematic, high-throughput profiling of oral microbiome with regard to long-term NG tube feeding among the older patient population.

The effect of clockwise and counterclockwise twisting moments on abutment screw loosening.

OBJECTIVES: Abutment screw loosening is one of the most common complications of dental implants. When occlusal loading is applied, bending and twisting moments are counteracted by the implant-abutment connection held with the abutment screw. Restorations in different quarters of the oral cavity might bear clockwise or counterclockwise twisting moments that result from a regular chewing pattern. The aim of this study was to investigate the effect of different directional twisting moments on abutment screws. METHODS: Twenty 3i implants were divided into four groups of C, R, L, and O. Each assembly consisted of an implant, abutment, and superstructure. For group C, a cyclic load of 10-100 N for 10(6) cycles was applied centrally and perpendicular to the long axis of the implant, whereas for groups R and L, the same load conditions were applied eccentrically in clockwise and counterclockwise directions, respectively. Group O was left unloaded. The difference between the initial torque and post-load reverse torque was defined as the total torque loss. The data were analyzed by Kruskal-Wallis test. The surface of the abutment hexagon corners were examined with SEM after loading. RESULTS: No abutment screw loosening was found after loading. Total torque loss of groups C, R, L, and O were 10.50 ± 0.58, 9.56 ± 1.01, 9.98 ± 1.81, and 9.58 ± 0.94 Ncm, respectively. There were no statistical differences among the four groups. SEM observations showed marked burnishing at the hexagonal corners on the compression sides of the R and L groups. CONCLUSIONS: Within the limitations of this study, there was little effect of twisting moment direction on the total torque loss of an internal hexagon connection implant system. This could be attributed to the anti-twisting mechanism of the internal hexagon connection.

The effect of hyperbaric oxygen and air on cartilage tissue engineering.

There is an urgent need to develop tissue-engineered cartilage for patients experiencing joint malfunction due to insufficient self-repairing capacity of articular cartilage. The aim of this research was to explore the effect of hyperbaric oxygen and air on tissue-engineered cartilage formation from human adipose-derived stem cells seeding on the gelatin/polycaprolactone biocomposites. The results of histological analyses indicate that under hyperbaric oxygen and air stimulation, the cell number of chondrocytes in cartilage matrix was not significantly increased, but the 1,9-dimethylmethylene blue assay showed that the glycosaminoglycans syntheses markedly increased compared to the control group. In quantification real-time polymerase chain reaction results, the chondrogenic-specific gene expression of SOX9, aggrecan, and COL2A1 were compared respectively. Within the limitation of this study, it was concluded that 2.5 atmosphere absolute oxygen and air may provide a stress environment to help cartilage tissue engineering development.

Arecoline induced cell cycle arrest, apoptosis, and cytotoxicity to human endothelial cells.

Betel quid (BQ) chewing is a common oral habit in South Asia and Taiwan. BQ consumption may increase the risk of oral squamous cell carcinoma (OSCC), oral submucous fibrosis (OSF), and periodontitis as well as systemic diseases (atherosclerosis, hypertension, etc.). However, little is known about the toxic effect of BQ components on endothelial cells that play important roles for angiogenesis, carcinogenesis, tissue fibrosis, and cardiovascular diseases. EAhy 926 (EAHY) endothelial cells were exposed to arecoline, a major BQ alkaloid, for various time periods. Cytotoxicity was estimated by 3-(4, 5- dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay. The cell cycle distribution of EAHY cells residing in sub-G0/G1, G0/G1, S-, and G2/M phases was analyzed by propidium iodide staining of cellular DNA content and flow cytometry. Some EAHY cells retracted, became round-shaped in appearance, and even detached from the culture plate after exposure to higher concentrations of arecoline (> 0.4 mM). At concentrations of 0.4 and 0.8 mM, arecoline induced significant cytotoxicity to EAHY cells. At similar concentrations, arecoline induced G2/M cell cycle arrest and increased sub-G0/G1 population, a hallmark of apoptosis. Interestingly, prolonged exposure to arecoline (0.1 mM) for 12 and 21 days significantly suppressed the proliferation of EAHY cells, whereas EAHY cells showed adaptation and survived when exposed to 0.05 mM arecoline. These results suggest that BQ components may contribute to the pathogenesis of OSF and BQ chewing-related cardiovascular diseases via toxicity to oral or systemic endothelial cells, leading to impairment of vascular function. During BQ chewing, endothelial damage may be induced by areca nut components and associate with the pathogenesis of OSF, periodontitis, and cardiovascular diseases.

Evaluation of the potential denture covering area in buccal shelf with intraoral scanner.

Background/purpose: The characteristic of soft tissue changes in buccal shelf area during function is unclear. This study aimed for evaluating the potential denture covering area in buccal shelf area in different ranges of mouth opening by a digital approach. Materials and methods: Nineteen qualified dentate participants were enrolled. An intraoral scanner was used to record soft tissue in buccal shelf area in different ranges of mandibular opening, which were maximum intercuspation, 10 mm, 20 mm, and 30 mm of interincisal distance. The experiment was performed by two examiners. The common area of each range was generated within the clinically acceptable denture adaptation range, which was represented as the potential denture covering area. Data were statistically analyzed using descriptive statistic, one-way repeated measure ANOVA, intraclass correlation coefficient (ICC), and the Pearson correlation test. Results: Trends of the mean distance of the potential denture covering area increased from the frenum area to the second premolar and the first molar area then decreased in the second molar area, along with the ranges of mouth opening increased. The distance in the second molar area had drastic percentage changes during the mouth opening. The mean distances changed significantly when the mouth opening increased (P < 0.001). All ICC values of intra-, inter-rater reliability indicated good to excellent reliability. The correlation between the results from two examiners was strong (P < 0.001). Conclusion: The characteristic of the denture covering area posteriorly to the first molar area is inversely proportional in length to ranges of mouth opening.