Differences between Computer-Based and Paper-Based Assessments of the Clinical Reasoning Competency of Dental Students.

Clinical reasoning competency is essential for an appropriate clinical dental treatment. Among the tools for the assessment of clinical reasoning competency, computer-based testing (CBT) is considered more useful than paper-based testing (PBT), because teachers can control the timing of information given to the examinees. Such timings could possibly affect the thinking process of examinees. However, few studies reported differences of reasoning between the two testing modes. In the present study, we developed an assessment of clinical reasoning and applied it using CBT and PBT to compare the examinees' performance. The participants comprised 60 students in the fifth-year class in 2012 of the School of Dentistry, Faculty of Dentistry, Tokyo Medical and Dental University. The tests comprised 25 problems, each with four questions, totaling 100 questions. The contents of the questions were the same in CBT and PBT. The students were assigned to CBT (Group C, n = 30) and PBT (Group P, n = 30) groups, with an almost equal gender ratio in the groups. The difference between scores was analyzed with a univariate analysis of variance. No significant intergroup differences were found regarding the test duration, total score, and average score of each question. The number of problems with perfect marks was higher in Group P than in Group C (P < 0.05), probably because Group P students could access the information of the previous question (s) within a problem. Thus, the differences of the examinees' performance between the two testing modes were small.

Item response theory model highlighting rating scale of a rubric and rater-rubric interaction in objective structured clinical examination.

Objective structured clinical examinations (OSCEs) are a widely used performance assessment for medical and dental students. A common limitation of OSCEs is that the evaluation results depend on the characteristics of raters and a scoring rubric. To overcome this limitation, item response theory (IRT) models such as the many-facet Rasch model have been proposed to estimate examinee abilities while taking into account the characteristics of raters and evaluation items in a rubric. However, conventional IRT models have two impractical assumptions: constant rater severity across all evaluation items in a rubric and an equal interval rating scale among evaluation items, which can decrease model fitting and ability measurement accuracy. To resolve this problem, we propose a new IRT model that introduces two parameters: (1) a rater-item interaction parameter representing the rater severity for each evaluation item and (2) an item-specific step-difficulty parameter representing the difference in rating scales among evaluation items. We demonstrate the effectiveness of the proposed model by applying it to actual data collected from a medical interview test conducted at Tokyo Medical and Dental University as part of a post-clinical clerkship OSCE. The experimental results showed that the proposed model was well-fitted to our OSCE data and measured ability accurately. Furthermore, it provided abundant information on rater and item characteristics that conventional models cannot, helping us to better understand rater and item properties.

Effect of the haptic 3D virtual reality dental training simulator on assessment of tooth preparation.

BACKGROUND/PURPOSE: The haptic 3D virtual reality dental training simulator has been drawn attention as a educational strategy in Covid-19 pandemic. The purpose of this study is to investigate the feature of the haptics simulator in comparison with a conventional mannequin simulator by analyzing the assessment of products prepared by dental students using these two kinds of simulator. MATERIALS AND METHODS: The subjects were 30 students in the sixth-year classes of the faculty of dentistry. Abutments for a full cast crown were prepared by each subject using two kinds of simulator; one is the haptics simulator and the other is a mannequin simulator. For the resulted products, occlusal surface form, margin design, surface smoothness, taper angle, total cut volume and overall impression were rated by 3 evaluators. Score differences between two simulators were statistically analyzed. RESULTS: The kinds of simulator affected subject performance for margin design and total cut volume. The differences in cutting feeling between the simulators as well as variation of stereoscopic ability in subjects were considerable reasons. Evaluators' rating was affected by difference in simulators for occlusal surface form, total cut volume, and overall impression. This may have been due to variation of stereoscopic ability in evaluators. CONCLUSION: The unique characteristics of virtual reality, such as the simulated cutting sensation and the simulated three-dimensional images created by stereo viewers, affect operators' performance and evaluators' rating. It was suggested that educational programs need to be constructed taking account of the characteristics of virtual reality to make the best use of the haptics simulator.

A survey of oral health status, subjective oral symptoms and oral health behaviors among first-year dental students at a Japanese university.

PURPOSE: The rapid deterioration of oral health in young adults is an alarming problem in Japan. The aim of the present study is to investigate the oral health status, subjective oral symptoms and oral health behaviors of dental students. METHODS: Participants were 108 first-year students attending dental school in 2018-2019. Oral examinations were performed to assess dental caries indices, oral hygiene status, gingival bleeding on probing (BOP) and pocket depth. A self-administered questionnaire was used to assess subjective oral symptoms and oral health behaviors. RESULTS: The prevalence of decayed teeth (DT) and gingivitis (BOP ≥ 10%) were 43.5% and 50.0%, respectively. Having DT and gingivitis were significantly associated with poorer oral hygiene. No association was observed between DT and subjective symptoms. Having gingivitis was significantly associated with xerostomia, mouth-breathing and less use of interdental cleaning tools. Multiple logistic regression analysis for gingivitis yielded an odds ratio of 1.41 (95% confidence interval: 1.19-1.67) for plaque score, and 2.75 (1.27-5.98) for xerostomia. CONCLUSION: Since a relatively high ratio of students had DT and gingivitis without clear subjective symptoms, they require regular dental visits for early treatment and oral hygiene maintenance from the start of their time at university.

Association between positional changes in laboratory values and severity in subjects with obstructive sleep apnea syndrome.

INTRODUCTION: The aim of the study was to investigate the association between the difference (defined as the remainder, Rm) in laboratory values determined in the upright and supine positions and the severity of obstructive sleep apnea syndrome (OSAS). MATERIALS AND METHODS: Thirty-three Japanese male subjects with OSAS [apnea/hypopnea index (AHI: the number of apneas and hypopneas per hour) > or =5] underwent cephalometric analysis and measurements of nasal resistance in the upright and supine positions. Several parameters in a dental model and physical features were also analyzed. RESULTS: Significant associations of the logarithmic AHI, with neck depth, Rm for the facial axis, and the minimum airway behind the tongue in the supine position were found in multiple linear regression analysis. CONCLUSION: Our results suggest that neck depth, Rm for the facial axis and the minimum airway behind the tongue in the supine position may be determinants of the severity of OSAS.

Does second-hand smoke associate with tooth loss among older Japanese? JAGES cross-sectional study.

OBJECTIVE: Second-hand smoke (SHS) is considered a risk factor for a number of oral diseases. However, its influence on tooth loss, which is the final consequence of periodontal disease and caries, remains unknown. We aimed to evaluate the association between SHS experience and the number of remaining teeth among non-smoking older Japanese individuals. METHODS: Cross-sectional data from the Japan Gerontological Evaluation Study (JAGES) 2013 were used. From the 27,561 people ≥65 years of age who responded to a self-reported questionnaire (response rate = 71.1%), data of 18,865 respondents who had never smoked were analysed. Multinomial logistic regression with multiple imputations was applied to estimate the odds ratio of the frequency of SHS exposures on the number of remaining teeth. RESULTS: The prevalence of participants with ≥20 teeth, 10-19 teeth, 5-9 teeth, 1-4 teeth, and no teeth were 53.2%, 20.4%, 9.9%, 6.6%, and 9.9%, respectively. The proportion of participants with SHS was 37.5%. After adjusting for sex, the SHS experience tended to be associated with a lower risk of having the fewer number of remaining teeth (P < 0.05). However, after being adjusted for age and sex, participants with SHS exposure at "a few times a week" and "almost every day" were significantly associated with the fewer number of teeth. After adding all other covariates, compared to the participants without any exposure to SHS, the odds ratio for having no teeth rather than having ≥20 teeth among the participants with daily exposure to SHS was 1.35 (P < 0.01). CONCLUSION: Daily second-hand smoke was significantly associated with fewer remaining teeth based on the self-reported survey among older Japanese people.

Rise of blood pressure value in young patients at first visit at a dental university hospital in Japan.

BACKGROUND/PURPOSE: Hypertension is a risk factor for stroke and heart disease. Psycho-social reasons are thought to influence blood pressure fluctuation in the dental clinic, but no previous studies have investigated these relationships. In this study, we analyzed a correlation between patients' blood pressure values and their backgrounds. MATERIALS AND METHODS: We measured blood pressure in 4990 outpatients at our hospital. After determining the age groups in which blood pressure deviated from national averages, patients were classified into the Hypertension group and Normal group. Differences between these groups with regard to the prevalence of systemic disease, dental history and reasons for dental consultation were analyzed. RESULTS: Average systolic blood pressure of males in their 20's, 30's, 40's and females in their 20's, 30's, 40's, 50's was significantly higher than national averages. In these age groups, disease prevalence was significantly higher in the Hypertension group than in the Normal group. Furthermore, the Hypertension group expressed psycho-social reasons for dental consultation more frequently than the Normal group. CONCLUSION: Relatively younger patients tended to show higher systolic blood pressure. It was suggested that psycho-social backgrounds as well as medical causes influenced the blood pressure increase.

Properties of human dentin surface after ArF excimer laser irradiation.

Recently, improvement of the properties of dentin surface using dental lasers to increase bonding strength has been anticipated in the field of adhesive dentistry. The objective of this study was to investigate changes in the surface properties of human dentin after ArF excimer laser irradiation at different irradiation times, pulse repetition rates and energy densities. The SEM images of the irradiated surfaces were observed, and the contact angle and the roughness of the irradiated surface were measured. As a result, SEM demonstrated that the dentin surface became irregular following ArF excimer laser irradiation. When the energy density increased, the irregularity became more minute and dentinal tubules were more easily identified. By contrast, such changes were not observed when the irradiation time and pulse repetition rate were changed. Moreover, as energy densities increased, the contact angle tended to decrease and the surface roughness tended to increase. These results suggested that the area of the irradiated surface and wettability increased after irradiation with the ArF excimer laser. Consequently, irradiation with ArF excimer lasers could improve the surface properties and be potentially useful for adhesive dentistry.

Tensile strength of dentin after bleaching treatment.

The mechanical properties of dentin are changed after bleaching, although the effects of the bleaching conditions on the tensile strength of dentin have not been determined. In the current study, a tensile test of bovine dentin was conducted after bleaching and the effects of the bleaching conditions were investigated, including the number of bleaching times, the location where the bleaching agent was applied, and the kind of illumination. The weight of organic content in dentin before and after application of the agent was also measured. The results showed that the tensile strengths did not change after three times office bleaching procedure, and the location where the bleaching agent was applied, the kind of bleaching agent and the kind of illumination did not have influence on the tensile strength. On the other hand, organic component in dentin significantly decreased after application of the agent (p<0.05). Since the bleaching agent would potentially affect tensile strength with deterioration of collagen matrix, the frequency of bleaching treatment should be minimized in clinical use.

Effects of a small electric current on sterilization of a dental unit water line.

In the present study, water was circulated in a simulated dental unit water line with electrifying a small current. The morphology of the biofilm developed on inner surface of the water line and the number of heterotrophic bacteria were investigated to elucidate the effect of a low level electric current on the biofilms formation associated with bacteria reproduction. Destruction and malconformation of biofilms by electrification was observed using SEM, in addition to deformation and hypertrophy of the bacteria. By naked eye observation, small pieces, which were possibly exfoliated biofilms, were detected in electrified water. While an adherent, yellow gel was demonstrated on the inner surface of the water line without electrification. With electrification, the number of bacteria decreased during the first week, however the bacteria increased gradually after that. The number of bacteria without electrification was consistently greater than that with electrification and the difference was statistically significant (P<0.05). The predominant bacteria were identified as Sphingomonas paucimobilis. The excess chlorine levels decreased to a minimum value within one week. The small current appeared to have effects on biofilm formation of heterotrophic bacteria that resulted in enhanced chlorine sterilization of dental unit water. Thus, electrification has considerable potential for the extermination of bacterial biofilms in dental unit water lines.

Effects of exposure to 4-META/MMA-TBB resin on pulp cell viability.

Adhesive restorative systems have expanded the range of possibilities for direct pulp-capping technique, with evidences of clinical success in vital pulp therapy. However, quite few studies have described the direct responses of pulp cells following the application of resinous materials to pulp exposure. To address this issue, effects of exposure to an adhesive resin, 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane (4-META/MMA-TBB) resin on cellular activity were investigated in an established rat dental pulp cell line (RPC-C2A). RPC-C2A cells were cultured on normal plastic plates or the disks prepared from 4-META/MMA-TBB resin (Super Bond C&B) in a-MEM containing 10% FBS. After 3, 7 and 14 days, DNA content and alkaline phosphatase (ALP) activity were measured. Total RNA in each group was extracted and RT-PCR analysis was performed. Moreover, the live cell ratio was also evaluated by cytotoxicity assay after treatment with various concentrations of 4-META/MMA-TBB. At day 3, 7 and 14, amount of DNA and ALP activity of the cells on normal plastic plates and the one on the 4-META/MMA-TBB were comparable. Cells of both groups expressed mRNA of type I collagen (Coll), ALP, osteopontin (OPN), osteocalcin (OC), and bone morphogenetic protein (BMP-2). Furthermore, 4-META/MMA-TBB (10(-1)% or less) did not influence dead cell ratio in the confluent state. According to the results of these in vitro studies, exposure to this resinous material would not induce cytotoxic response in the pulp cells.

Study of finite element modeling from CT images.

The use of finite element analysis is becoming more widespread with rapid advancements in computer technology. However, the field of dentistry is not enjoying the spillover benefits of the expanded use of this design simulation and analysis tool. Finite element modeling requires measurement of the object. However, as the living body is morphologically very complex, this requires a great deal of both time and skill using CAD applications, thus preventing its widespread adoption in the dental field. Although there have been reports of finite element modeling from CT images, these methods require skilled programmers for software development--which is another factor that prevents its widespread adoption in dentistry. Therefore, establishing a finite element modeling method that is both accurate and practical will be of great benefit in clinical dentistry. In the present study, a method using computer tomography and existing software was examined for finite element model construction based on computer tomography images. The results suggested that the method developed here is feasible and practical for clinical use.

[Educative effect of feedback after medical interview in objective structured clinical examination].

OBJECTIVE: Objective Structured Clinical Examination (OSCE) is widely used to assess the core competency of dental residents. However, the educative effect of feedback in OSCE has not been fully examined. Therefore, we investigated the educative effect of formative feedback in a medical interview station. METHODS: The subjects were 51 residents in the clinical training course of our dental hospital. After completing the medical interview station, residents were individually given formative feedback by evaluators and standardized patients. Two months later, residents were asked to fill in a questionnaire about the contents of feedback and self-rating mental strain level during OSCE. Videotaped performance and feedback were reviewed by investigators to check the answers to the questionnaire. RESULTS: Evaluators provided an average of 3.1 feedback items, and standardized patients provided an average of 1.6 feedback items for each resident. However, each resident remembered an average of 1.3 feedback items from evaluators and 0.9 from standardized patients. The lower the score of residents in the medical interview station, the more feedback items were given to residents. A significant negative correlation was found between the score of evaluators and self-rating mental strain level (Spearman rho = -0.326, p = 0.019). CONCLUSION: For effective feedback, evaluators or standardized patients should focus on 2 to 3 items of essential points in OSCE. Repetition of feedback using videotaped performance may be useful to improve communication skills for medical interview.

Resin-dentin bonding interface after photochemical surface treatment.

OBJECTIVE: The aim of this study is to elucidate the structure of the resin-dentin interface formed by photochemical dentin treatment using an argon fluoride (ArF) excimer laser. BACKGROUND DATA: The ArF excimer laser processes material by photochemical reaction without generating heat, while also providing surface conditioning that enhances material adhesion. In the case of bonding between resin and dentin, we demonstrated in a previous study that laser etching using an ArF excimer laser produced bonding strength comparable to that of the traditional bonding process; however, conditions of the bonding interface have not been fully investigated. METHODS: A dentin surface was irradiated in air with an ArF excimer laser followed by bonding treatment. Cross sections were observed under light microscope, transmission electron microscope (TEM), and scanning electron microscope, then analyzed using an energy dispersive X-ray spectroscope (EDS): EDS line profiles of the elements C, O, Si, Cl, P, and Ca at the resin-dentin interface were obtained. RESULTS: The density of C in resin decreased as it approached the interface, reaching its lowest level within the dentin at a depth of 2 µm from the resin-dentin interface on EDS. There was no hybrid layer observed at the interface on TEM. Therefore, it was suggested that the resin monomer infiltrated into the microspaces produced on the dentin surface by laser abrasion. CONCLUSIONS: The monomer infiltration without hybrid layer is thought to be the adhesion mechanism after laser etching. Therefore, the photochemical processes at the bonding interface achieved using the ArF excimer laser has great potential to be developed into a new bonding system in dentistry.

Effects of chloramines and sodium hypochlorite on carious dentin.

In chemo-mechanical caries removal procedures, chloramines are typically used for chemical softening of carious dentin. However, the specific effect of chloramines to be compared to sodium hypochlorite has not been sufficiently clarified. In present study, the effect of chloramines used in the Carisolv-system on carious dentin mechanical properties and morphology were investigated, using Vickers hardness test and scanning electron microscopy (SEM). Sections of permanent teeth with dentin caries were treated with chloramines, prepared by mixing amino acids (glutamic acid, lysine, and leucine) with sodium hypochlorite or with sodium hypochlorite alone or with purified water. There was a tendency that the application of the sodium hypochlorite solution softened the sound dentin and/or inner layer of carious dentin more than the application of the chloramines solution did. In SEM observations, the application of chloramines resulted in opening dentinal tubules in the outer layer of carious dentin: Occluded dentinal tubules were seen after sodium hypochlorite application. There is a possibility that the amino acids in the Carisolv-system decrease the aggressive effect of sodium hypochlorite on sound dentin and/or inner layer of carious dentin and also would enhance the disrupting effect on degenerated collagen in carious dentin outer layer.

Evaluation of an articulated measuring apparatus for use in the oral cavity.

The aim of this study was to evaluate the trial Teaching Robot for the development of a contact-type measuring apparatus for using directly in the oral cavity. A standard model was used to mimic the dentition by placing an arrangement of three bearing balls. The diameters of the balls were measured. A practical dentition model was used. The coordinates were measured on the top of the buccal cusp of the right and left first premolars and the distal contact points of the right and left first molars and the mesial contact point of the right incisor. The arch width and length were calculated. The diameters of the bearing balls and the widths and lengths of the dental arches were not significantly different from the results of the XYZAX G-800D. Therefore, we suggest that the trial Teaching Robot has superior efficiency for measurements in oral cavity.

Effects of ArF excimer laser irradiation of dentin on the tensile bonding strength to composite resin.

OBJECTIVE: The purpose of the study was to evaluate the effects of argon fluoride (ArF) excimer laser irradiation on the tensile bonding strength (TBS) of dentin to composite resin. BACKGROUND DATA: Dental lasers use a photothermal process, which potentially entails risk of tissue damage caused by heat affecting the bond strength of resins. The ArF excimer laser functions by a photochemical process in which the energy of photons directly cuts covalent bonds in molecules without generating heat. METHODS: Twenty extracted human molars were sectioned perpendicularly to the tooth axis to expose a flat dentin surface. The surfaces were treated with various combinations of ArF excimer laser irradiation, primer treatment, and bonding treatment. After composite resin was built up on the treated dentin surface, specimens with a 1×1 mm bonding interface were prepared and subjected to TBS tests. Treated dentin surfaces were also observed using transmission electron microscopy (TEM). RESULTS: Specimens that underwent laser irradiation followed by bonding treatment had a TBS that did not differ significantly from that of specimens that received conventional treatment, with or without priming. TEM observations showed sectioned and dispersed collagen matrix in the hybrid layer after laser irradiation, priming, and bonding, but no hybrid layer after laser irradiation and bonding at the treated dentin surface. CONCLUSIONS: The TBS of conditioning with ArF excimer laser irradiation was identical to that with conventional treatment when bonding was used. The bonding mechanism with the ArF irradiation differed from that of conventional bonding depending upon dentin hybridization.

The possibility of digital imaging in the diagnosis of occlusal caries.

The aim of this study was to assess the possibility of digital image analysis of pit-and-fissure discoloration in order to diagnose caries. Digital images showing pit-and-fissure discoloration in 100 teeth of 19 patients were analyzed to obtain the fractal dimension (FD) and the proportion of the area of pit-and-fissure discoloration to the area of occlusal surface (PA). DIAGNOdent values were measured (DD), and dentists' diagnoses were also obtained. The sensitivity and specificity of FD, PA, DD, and the combination of FD and PA compared to the dentists' diagnoses were calculated. The sensitivities of FD, PA, DD, and the combination of FD and PA were 0.89, 0.47, 0.69, and 0.86, respectively, and the specificities were 0.84, 0.95, 0.91, and 0.86, respectively. Although further research is needed for the practical use, it is possible to use the analysis of digital images of pit-and-fissure molar discoloration as a diagnostic tool.