Evaluating dental student self-assessment across preclinical anatomy waxing and operative exercises

PURPOSE/OBJECTIVE

A career in healthcare is built on the foundations of continuous self-reflection and self-assessment. Previous studies have solely compared student self-assessment to faculty grades in a single discipline. The objective of this study was to investigate whether associations of a student's self-assessment skills exist across multiple disciplines in the predoctoral setting.

METHODS

Sixty-five students from two class years at the Harvard School of Dental Medicine completed preclinical competency exams in dental anatomy waxing and operative dentistry. The difference between the student's self-assessment score and average faculty grade for each exercise was calculated as the student‒faculty (S-F) gap, which served as a proxy to determine how students evaluate their work. Regression analysis was performed to assess associations between wax-up and preclinical operative S-F gaps.

RESULTS

Mean S-F gaps for waxing and preclinical operative procedures were positive (5.7 ± 6.1 and 7.6 ± 6.7, respectively). Additionally, students in the lower quartile tended to overestimate performance to a greater degree than their peers in the upper quartile. Furthermore, the waxing S-F gaps were positively associated with S-F gaps of each operative procedure, particularly with the combined operative exercise S-F gaps, where a statistically significant association was seen (coefficient = 0.28; p = 0.04).

CONCLUSION(S)

Previously, we identified a negative correlation between students' self-assessment skills (S-F gaps) and their preclinical performance. In this study, we further demonstrated an association of S-F gaps in two fundamental exercises: wax-up and operative dentistry. This underscores the roles of S-F gaps as possible indicators of students' preclinical and clinical performance, and it holds potential to become a widely standardized and applicable calculation that may help evaluate the effectiveness of the dental curricula and optimize student learning.

Association of student performance between dental anatomy waxing and preclinical operative dentistry

Spatial perception and psychomotor skills are critical components to clinical dentistry. However, measures within the dental school curricula have not been sufficiently studied and evaluated for their effectiveness in predicting preclinical performance. The objective of this study was to examine whether students' waxing skills are associated with preclinical operative performance. This study included 65 students from two class years at the Harvard School of Dental Medicine. Regression analysis was utilized to assess associations between waxing scores and operative exam scores. Waxing scores were found to be positively correlated with all operative practical exam scores and significantly associated with the class III resin composite restoration (coefficient, 0.42; P = 0.02) and the combined operative exam scores (coefficient, 0.33; P = 0.04). Wax-up assessments could serve as a predictor for preclinical performance and identify students who would benefit from additional assistance to help foster a more inclusive learning environment.

Dental Student Perceptions of Distance Education over Time: A Mixed-Methods Study

OBJECTIVES

Amid the COVID-19 pandemic, the transition to distance learning raised pertinent questions regarding advantages and challenges compared to traditional in-person learning. This study aimed to investigate dental students' perceptions of distance learning throughout the pandemic, examining its impact on their education.

METHODS

This study employed a convergent mixed-methods design. Three online surveys were conducted in 2020, 2021, and 2022 to collect quantitative data. Additionally, qualitative semi-structured interviews were carried out in 2022. Interviews were recorded and transcribed; then, thematic analysis was performed following an inductive approach.

RESULTS

As perceived by the participants, distance learning entails advantages and challenges. Initially, they felt uncertainty and negativity about the new environment with distance learning. However, their perceptions shifted positively as they adapted, even after returning to hybrid and in-person modules. Furthermore, most participants felt that distance learning is better suited for didactic content. It was suggested that didactic courses contain approximately 25-50% of online methods.

CONCLUSIONS

Distance learning has provided valuable opportunities to reinforce curricula and improve learning efficacy during the pandemic. Our findings suggest that a hybrid learning model that combines traditional and distance modules appears to be an effective approach for future dental education.

3D Digital technology as an alternative educational tool in preclinical dentistry

INTRODUCTION

The advancement of 3D digital scanners has allowed educators to uphold the quality of education whilst implementing novel methods of assessment.

OBJECTIVE

The purpose of this study was to compare two evaluation methods, conventional and digital scanned assessments, on student cavity preparations and students and faculty's perceptions of these assessment methods.

METHODS

Predoctoral students performed Class II amalgam and Class III resin composite preparations on simulated teeth for their preclinical competency examinations. Two calibrated faculty evaluated the students' preparations using dental instruments for conventional assessments and 3D scanned images for digital assessments. Faculty scores from both assessment methods were compared and statistically analysed (p < .05). Students also self-assessed their performance using the digital scanned images and filled out a perception survey.

RESULTS

There was no statistically significant difference between the conventional (Class II; 73.3 ± 12.2 and Class III; 82.5 ± 8.9) and the digital assessment with scanned images (Class II; 71.3 ± 11.0 and Class III; 82.2 ± 8.2). Faculty scores from both methods have shown a trend of comparability. Most students agreed that digital ideal preparation models were useful (84.2%) and almost all students agreed that digital technology helped them learn operative dentistry (91.1%). In contrast, most students agreed that conventional assessment should be the main self-evaluation system (82.2%) and disagreed that digital assessment is more effective than conventional self-assessment (68.3%).

CONCLUSION

Our study demonstrated that 3D digital technology could be an alternative and/or supplementary educational tool to aid in upholding the quality of dental education.

Predoctoral Student Performance in a Restorative Dentistry Course During the COVID-19 Pandemic

PURPOSE

To compare predoctoral student performance in restorative dentistry related to curricular changes implemented in response to the COVID-19 pandemic and to evaluate the impact of remote education on performance in didactic and preclinical examinations and objective structured clinical examinations (OSCEs).

MATERIALS AND METHODS

The study population consisted of 172 students, all members of the DMD graduating classes from 2017 to 2021. Scores in the Final Restorative Treatment (FRTx) course, subdivided into didactic and preclinical lab work, and the OSCEs were assessed and compared between pre-pandemic students and during-pandemic students.

RESULTS

Performance in the preclinical lab exercises was statistically significantly higher in the during-pandemic cohort than in the pre-pandemic cohort after adjusting for students' gender and admission scores. Performance in restorative dentistry as measured by the OSCE was not statistically different among during-pandemic students compared to the pre-pandemic students. It was observed that students were more efficient and engaged during the more limited lab sessions with the increased student-to-faculty ratio that allowed for more feedback.

CONCLUSION

Although virtual education cannot replace in-person experiences, this model served students satisfactorily during the COVID-19 pandemic, with added support structures such as flexible scheduling, interactive sessions, and additional small-group discussions to maintain academic performance in predoctoral education.

Effect of an experimental chitosan/casein gel on demineralized enamel under a cariogenic challenge

BACKGROUND

Dental caries is considered one of the most common oral health diseases.

OBJECTIVES

The aim of the study was to evaluate the effects of an experimental chitosan/casein gel on enamel demineralization/remineralization in an environment with a high cariogenic challenge.

MATERIAL AND METHODS

Thirty-six specimens of bovine enamel (4 mm × 3 mm × 2 mm) were ground flat and polished. Then, the specimens were immersed in acetate buffer for 43 h with half of the surface protected (serving as control) and the other half exposed. All demineralized surfaces were randomly assigned into 3 groups (n = 12 per group) according to the type of treatment (G1 - control, G2 - 1.5% chitosan gel with 1.5% casein, and G3 - 1.5% chitosan gel without casein), and the corresponding treatment was applied once a week for 3 weeks. The specimens were also subjected to pH cycles of demineralization/ remineralization and the treatments were performed 3 times at 7-day intervals for a total of 21 days. Surface images were obtained for the analysis of initial roughness and, after the cariogenic challenge, new images were obtained to evaluate the final roughness, volume loss and wear profile using laser confocal microscopy. After the analyses, the specimens were cut and the depth of demineralization was measured. The data were analyzed using the Kruskal-Wallis analysis of variance (ANOVA) and the Tukey's test.

RESULTS

While the chitosan gel with casein showed a similar loss to the control group (p > 0.05), both gels resulted in similar volume loss (p > 0.05). There were no statistical differences regarding the wear profile, surface roughness and depth of demineralization between the groups (p > 0.05).

CONCLUSIONS

The chitosan gel reduced volume loss of the demineralized enamel without significantly impacting the surface smoothness.

Association of admissions factors with student performance in preclinical operative dentistry

PURPOSE/OBJECTIVE

Admission to dental school is based on various factors including academic achievements in undergraduate coursework and the Dental Admission Test (DAT) scores. Students' success in an operative course requires fundamental knowledge, hand skills, spatial awareness, and self-assessment ability. The goal of this study is to evaluate how admissions factors, such as Grade Point Average (GPA) and DAT, including the Perceptual Ability Test (PAT), relate to students' academic and preclinical performance and self-assessment skills in preclinical operative dentistry.

METHODS

A total of 239 students were included from seven class years (2016-2022). Third-year dental students participated in a preclinical operative dentistry course. At the end of the course, they took the final multiple-choice exam and performed four competency examination procedures: Class II amalgam preparation and restoration and Class III resin-composite preparation and restoration. Calibrated faculty graded students' work independently and students also self-assessed their performance using the same rubrics as faculty. Linear regressions were performed to estimate the association between the admission factors with the mean faculty scores (measuring preclinical performance), student-faculty (S-F) gap scores (evaluating self-assessment skills), and their final didactic exam scores.

RESULTS

Overall, students' self-assessment was higher compared to faculty score. Linear regression analysis demonstrated positive correlations between the PAT and students' preclinical performance as well as between the DAT and their didactic exam scores. In general, S-F gap score decreased as PAT score increased, and it was statistically significant lower for the Class III preparation, indicating a better self-assessment skill. No correlations were observed between student performance and GPA scores.

CONCLUSION

The findings from the association between student performance and admission factors may play an important role in the dental school admissions process and assist students who may benefit from early faculty intervention and support.

The impact of COVID-19 pandemic on student performance and self-evaluation in preclinical operative dentistry

INTRODUCTION

During the COVID-19 pandemic, dental schools were required to reformat their curricula to accommodate regulations mandated to protect the health of students and faculty. For students enrolled in the Operative Dentistry preclinical courses at the Harvard School of Dental Medicine (HSDM), this modified curriculum included frontloading the course with lectures delivered remotely, followed by in-person laboratory exercises of learned concepts. The aim of this article was to determine the impact that the modifications had on student performance and student self-evaluation capabilities.

MATERIALS AND METHODS

Thirty-eight students were introduced to this restructured course. Their performance in a final multiple-choice (MC) examination, four preclinical laboratory competency assessments (class II amalgam preparation and restoration, class III composite preparation and restoration) and their self-assessment of these preclinical competency assessments were then compared with the pre-COVID pandemic (P-CP) classes from years 2014 to 2019 (n = 216 students). Linear regressions were performed to determine differences in mean faculty scores, self-assessment scores, student-faculty score gaps (S-F gaps) and absolute S-F gaps seen between the class impacted by the pandemic and the P-CP classes.

RESULTS

The results demonstrated that students during the COVID-19 pandemic (D-CP) had a higher average faculty score in all four preclinical laboratory competency assessments and in the final MC examination. In addition, the S-F gap was smaller in this cohort as compared with the P-CP classes.

CONCLUSION

Despite the challenges of restructuring the preclinical curricula, D-CP students performed better than their P-CP predecessors in multiple facets of this Operative Dentistry course including self-assessment accuracy.

Importance of bitewing radiographs for the early detection of interproximal carious lesions and the impact on healthcare expenditure in Japan

Background

Globally, the direct cost of dental caries is approximately $298B yearly, consuming 5–10% of national healthcare budgets. Bitewing radiographs (BWR) are the standard method of diagnosing interproximal dental caries. In Japan, bitewing radiographs are rarely used. This retrospective observational study was conducted to measure the potential economic impact of carious lesions left undiagnosed and untreated due to this omission of bitewing radiographs.

Methods

The total number of existing carious lesions, the number of undiagnosed lesions, and costs of treating these lesions were calculated from the national database of Ministry of Health, Labor and Wellness in Japan between June 2013 and 2017. The number of affected teeth was estimated using prevalence data and undiagnosed lesions were estimated. The expense associated with treating progressed lesions was calculated using the standard Japanese fee structure. BWR trends were assessed, and analyses were performed to understand the differences between states and populations over time.

Results

The average number of BWR taken monthly per office was 48.3±1.1 (average ± SD). It was calculated that an average of 6,429,155 lesions went undiagnosed per month, 93.5 teeth per practice, and 1.6 teeth per patient. The cost of treating lesions that went undiagnosed and then progressed into more invasive restorations was estimated to be between $57M–$218M more (difference between NaF varnish and class II restorations), and $150M–$443M more (difference between Class II restoration and crown or crown with RCT).

Conclusions

BWRs are crucial in diagnosing a significant number of carious lesions. There is considerable impact on health and cost to the national health system due to undiagnosed lesions. Practitioners need to be educated on reading and understanding BWR, and policy should be changed to cover BWR.

Comprehensive review of the incisive branch of the inferior alveolar nerve

The incisive branch of the inferior alveolar nerve is a vital anatomical structure within the anterior mandible that has not been thoroughly defined and outlined in reports in the literature until recent years. Advances in radiological imaging, particularly the widespread use of cone-beam computed tomography has allowed for accurate visualization of the mandibular incisive canal (MIC) and its associated incisive branch of the inferior alveolar nerve. Surgical damage to the MIC, which could result in hemorrhage and sensory disturbance, may occur in commonly practiced oral and maxillofacial procedures, such as chin bone harvesting, implant placement, fracture repair and removal of pathologic entities of the anterior mandible. Knowledge of both the presence, dimensions and location of the incisive branch is a vital component to pre and peri-operative planning of oral and maxillofacial surgeries performed within the mandible, particularly within the interforaminal zone. In this article, the terminology, anatomy, imaging, surgical consideration, and pathology of the incisive branch will be discussed.

Comparing dental student preclinical self-assessment in the United States and Japan

PURPOSE/OBJECTIVES

Self-assessment is an essential skill for dental professionals. Understanding global trends in self-assessment can highlight the learning needs of students across a diversity of cultural backgrounds. The aim of this study is to compare the self-assessment ability of dental students in the United States and Japan, where cultural backgrounds may differ.

METHODS

Students in the United States (n = 176) completed a typodont premolar and anterior Class II and Class III preparation and restoration. Students in Japan (n = 175) completed a typodont premolar crown preparation. Students and faculty then evaluated the student performance using rubrics for each respective procedure. The difference between the student's self-assessment score and the average faculty score (S-F gap) was calculated and the data were analyzed.

RESULTS

The mean S-F gap was 2.8% in Japan and 7.6% in the United States. This indicates that Japanese students tended to assess themselves closer to their faculty graders than students in the United States. On average, students in both countries scored themselves higher than their faculty graders. Students in the United States more frequently overestimated their performance and students in Japan more frequently underestimated their performance. For students in the lower quartile, the mean S-F gap was 5.1% in Japan and 14.6% in the United States, indicating a large cultural discrepancy in the lower quartile groups.

CONCLUSIONS

Although different preclinical procedures were compared, our findings demonstrated that Japanese students may score themselves more closely to their faculty assessors than students in the United States. Further investigation with more students completing the same preclinical activity will be needed.

Clinical anatomy of the inferior labial gland: a narrative review

Objective

In this article we review the literature on the inferior labial gland from a clinical and anatomical perspective.

Background

Regardless of its importance in clinical practice, there are no medical literature that comprehensively reviewed the inferior labial gland.

Methods

A database search using PubMed and Google Scholar was conducted. The following keywords were used in the search: "lower labial salivary gland", "lower labial gland", "inferior labial salivary gland", AND "inferior labial gland".

Conclusions

The human labial glands are types of minor salivary gland that continuously secrete small amounts of mucous and serous substances to maintain oral health. The inferior labial glands are innervated by the inferior labial branch of the mental nerve, and the inferior labial branch of the facial artery is the main arterial supply to the lower lip. Although they only have an auxiliary role in saliva production compared to the major salivary glands, minor salivary glands provide a certain amount of lubrication in the oral cavity by the continuous outflow of saliva. The inferior labial gland not only promotes moisturization in the oral cavity but also secretes substances with antibacterial effects, which is important for the function of the oral cavity. A recent study showed that the rate of salivary secretion from the inferior labial glands does not change with age, and in some cases the inferior labial glands are used for diagnosing intractable diseases such as Sjogren's syndrome and cystic fibrosis. In addition, since the inferior labial glands themselves can be the site of cyst and/or neoplasia development, we should be careful to distinguish them from other diseases. Elucidation of the anatomy, physiology, and pathology of the inferior labial glands, is important for understanding human health and diseases.

The effect of gender on student self-assessment skills in operative preclinical dentistry

PURPOSE/OBJECTIVE

Self-assessment is a fundamental skill for dentists and other health care providers. It enables these professionals' ability to critically evaluate the quality of their clinical work and improve through self-directed learning. Researchers have investigated how gender affects self-assessment skills and have shown that male students tend to overestimate their performance while female students tend to underestimate theirs as compared to peer or faculty assessment. The goal of this study was to evaluate how the self-assessment skills of dental students differ by gender in operative preclinical dentistry.

METHODS

Third-year dental students (N = 208, Class of 2016-2021) self-assessed their work using the same rubrics as faculty on four operative dentistry competency examination procedures: Class II amalgam preparation and restoration and Class III resin-composite preparation and restoration. Two calibrated full-time faculty graded all procedures independently. The Student self-assessment-Faculty grade (S-F) gap scores were calculated and statistically analyzed.

RESULTS

Overall, both genders overestimated their self-assessment for all four procedures as compared to actual scores given by faculty. Males overestimated more significantly than females for Class II Amalgam preparation, but not for the other three procedures. However, when the S-F gap for all procedures was combined and analyzed together, male students significantly overestimated their self-assessments compared to female students. When female and male students grading scores were stratified into quartiles, there were significantly larger differences between males and females in the lower quartiles, which suggest that difference in self-assessment abilities was more prominent among the lower performing students.

CONCLUSION

The results of this study demonstrate that gender may affect the accuracy of self-assessment in operative preclinical dentistry.

Decision tree protocol for demineralized gingival margin extension in class II composite cavity preparations

This study proposed the development of a protocol for class-II preparations with demineralized gingival margins for the improvement of the longevity of restorations. Evidence sources such as location/color/surface hardness/width of demineralized gingival margin with enamel/demineralized enamel (DE)/dentin/cementum were reviewed based on methodological studies and systematic reviews. A decision tree protocol was developed with criteria (i) lesion location: demineralized gingival margins in enamel must be removed, but if close to cementoenamel-junction, color should be evaluated. (ii) Color: yellow/brown lesions must be removed, but if white/opaque, then the surface hardness should be evaluated. (iii) Surface hardness: soft/demineralized gingival margin must be removed, but if adequately hard, width should be evaluated. (iv) Width: lesions less than half-enamel thickness and impenetrable by an explorer, remineralization is possible and the lesion does not need to be removed. A decision tree protocol was set up with the current available literature. Further continued investigations will be needed for the appropriate protocol updates.

Can an interactive case-based activity help bridge the theory-practice gap in operative dentistry?

INTRODUCTION

A theory-practice gap in pre-doctoral dental education is a common source of stress for dental students. An interactive, small-group, case-based activity was designed to bridge the gap between pre-clinical and clinical experiences. The aim of our study was to assess the effectiveness of the case-based activity by evaluating students' comfort level in operative procedures.

MATERIALS AND METHODS

Over 5 years, a total of 172 second-year students from the classes of 2017 through 2021 participated in the case-based activity delivered after the completion of the core operative dentistry course. The exercise included a pre-activity online quiz, an in-class case-based session and a laboratory exercise. Students' self-reported comfort levels in performing operative procedures were collected by surveys at three different times. They included the post-course survey distributed after the completion of the core operative dentistry course, the post-activity survey distributed after the completion of the case-based activity, and the follow-up survey distributed after students completed their first operative procedures in clinic.

RESULTS

There was a 93% response rate. The average rating of all eight statements revealed statistically significant increase in students' comfort level after completing the case-based activity and after performing their first operative procedures in the teaching practice.

CONCLUSION

This observation suggests that the case-based activity was effective in raising students' comfort levels. The activity may serve as an important tool in bridging the theory-practice gap between pre-clinical and clinical operative experiences.

Effects of healthcare policy and education on reading accuracy of bitewing radiographs for interproximal caries

Objectives

The aim of this study is to assess the accuracy of bitewing radiograph interpretation of predoctoral students, residents and general dentists who work under different core curriculum of dental education and healthcare policy.

Methods

A total of 118 examiners including predoctoral dental students, residents and general dentists from USA and Japan were tasked with evaluating a series of bitewing radiographs and diagnosing interproximal carious lesions. This study was approved by the Harvard Medical School Institutional Review Board (IRB). Participants graded interproximal aspects of those images and categorized the following criteria; “intact”, “enamel caries <1/2 width”, “enamel caries >1/2 width” or “caries into dentin”. The gold-standard was determined by the consensus of two HSDM full-time faculty.

Results

There was significant difference in the sensitivity for all three caries levels between the two groups but there was no significant difference on specificity. The positive-predictive and negative-predictive values of the USA group for the enamel caries (<1/2 of enamel) were significantly higher than the Japanese group. The average of AUC (ROC) was significantly higher in the USA group (0.885 ± 0.04) than the Japanese group (0.785 ± 0.08, p<0.01).

Conclusion

Teaching and adopting BW radiographs for diagnosis of interproximal caries is integral for dental providers to accurately and efficiently use them in their practices. It is critical that all dental educators approach policymakers to explain the importance of BW radiographs and promote their efficacy for prevention and early diagnosis of interproximal caries.

Dual innervation of the mylohyoid muscle by the trigeminal and hypoglossal nerves: A case report

During the routine dissection of a cadaveric specimen, the left mylohyoid muscle was found to be innervated by both the trigeminal and hypoglossal nerves. This variation was found unilaterally. To our knowledge this dual innervation of the mylohyoid muscle is an extremely rare variation. The possibility of these variants may lead to clinical consequences such as anesthesia failure and iatrogenic injury during surgical procedures in this region. We discuss this anatomical variation and possible developmental etiologies.

A rare case of trifid mandibular canal with bilateral retromolar foramina

There are many reported anatomical variations of the mandibular canal. Consequently, there is great variation in the retromolar area, such as the quantity, size, and location of the retromolar foramen (RMF), the bony entrance of the retromolar canal (RMC). These variations allow for different accessory innervations to the mandibular molars and their adjacent buccal tissue because the RMC contains neurovascular bundles. Consideration of these anatomical variations is crucial for avoiding complications in anesthesia, implant placement, and surgery. However, the rarer canal types are often only imaged by computed tomography (CT) or cone beam computed tomography (CBCT). We present a rare case with bilateral RMF and a unilateral trifid mandibular canal in a cadaver.

Toward High Precision XCO2 Retrievals From TanSat Observations: Retrieval Improvement and Validation Against TCCON Measurements

TanSat is the 1st Chinese carbon dioxide (CO2) measurement satellite, launched in 2016. In this study, the University of Leicester Full Physics (UoL-FP) algorithm is implemented for TanSat nadir mode XCO2 retrievals. We develop a spectrum correction method to reduce the retrieval errors by the online fitting of an 8th order Fourier series. The spectrum-correction model and its a priori parameters are developed by analyzing the solar calibration measurement. This correction provides a significant improvement to the O2 A band retrieval. Accordingly, we extend the previous TanSat single CO2 weak band retrieval to a combined O2 A and CO2 weak band retrieval. A Genetic Algorithm (GA) has been applied to determine the threshold values of post-screening filters. In total, 18.3% of the retrieved data is identified as high quality compared to the original measurements. The same quality control parameters have been used in a footprint independent multiple linear regression bias correction due to the strong correlation with the XCO2 retrieval error. Twenty sites of the Total Column Carbon Observing Network (TCCON) have been selected to validate our new approach for the TanSat XCO2 retrieval. We show that our new approach produces a significant improvement on the XCO2 retrieval accuracy and precision when compared to TCCON with an average bias and RMSE of -0.08 ppm and 1.47 ppm, respectively. The methods used in this study can help to improve the XCO2 retrieval from TanSat and subsequently the Level-2 data production, and hence will be applied in the TanSat operational XCO2 processing.

A comparison of diagnosis of early stage interproximal caries with bitewing radiographs and periapical images using consensus reference

OBJECTIVES:

The purpose of this study was to assess the diagnostic property of intraoral bitewing radiographs (BTW) for early stage interproximal caries, and to compare them with periapical radiographs (PA) at different levels of caries progression.

METHODS:

A total of 241 interproximal surfaces of BTW and corresponding PAs were used. Seven teaching faculty consisting of three oral and maxillofacial radiologists, two operative faculty, and two prosthodontists evaluated the images. The observers graded images as either "intact", "enamel caries <1/2 width", "enamel caries >1/2 width", or "caries into dentin". The gold-standard was established by consensus of two experienced faculty with 35 years and 27 years of experience. Specificity, sensitivity, positive-predictive value, and negative-predictive value were calculated for the different level of caries progression. Furthermore, receiver operating curves) of BTW and PAs of each evaluator were made and the area under the curve of BTW and PAs were compared.

RESULTS:

There was no significant difference in the specificity of BTW and PAs. BTW showed significantly higher sensitivity than PAs in all levels of caries progression (p<0.01). Positive-predictive value and negative-predictive value of BTWs were also significantly higher than PAs. One-way ANOVA and Tukey HSD test showed a significant difference in sensitivity with different levels of caries progression. The average area under the curve was significantly higher for BTWs than PAs (p<0.01).

CONCLUSIONS:

BTWs offer a significant advantage over PAs in the diagnoses of early stages of interproximal carious lesions.

The Role of Digital 3D Scanned Models in Dental Students' Self-Assessments in Preclinical Operative Dentistry

The aim of this study was to determine how dental student self-assessment and faculty assessment of operative preparations compared for conventional visual assessment versus assessment of scanned digital 3D models. In 2016, all third-year students in the Class of 2018 (N=35) at Harvard School of Dental Medicine performed preclinical exams of Class II amalgam preparations (C2AP) and Class III composite preparations (C3CP) and completed self-assessment forms; in 2017, all third-year students in the Class of 2019 (N=34) performed the same exams. Afterwards, the prepared typodont teeth were digitally scanned. Students self-assessed their preparations digitally, and four faculty members graded the preparations conventionally and digitally. The results showed that, overall, the students assessed their preparations higher than the faculty assessments. The mean student-faculty gaps for C2AP and C3CP in the conventional assessments were 11% and 5%, respectively. The mean digital student-faculty gap for C2AP and C3CP were 8% and 2%, respectively. In the conventional assessments, preclinical performance was negatively correlated with the student-faculty gap (r=-0.47, p<0.001). The correlations were not statistically significant with the digital assessments (p=0.39, p=0.26). Students in the bottom quartile significantly improved their self-assessment accuracy using digital self-assessments over conventional assessments (C2AP 10% vs. 17% and C3CP 3% vs. 10%, respectively). These results suggest that digital assessments offered a significant learning opportunity for students to critically self-assess themselves in operative preclinical dentistry. The lower performing students benefitted the most, improving their assessment ability to the level of the rest of the class.

The Relationship Between Dental Students' Assessment Ability and Preclinical and Academic Performance in Operative Dentistry

Self-assessment is a critical skill for health care professionals. Because these professionals must be lifelong, self-directed learners and self-regulating practitioners, the ability to self-assess is essential for them. The aims of this study were to measure how dental students self-assessed and peer-assessed their performance in preclinical operative procedures and to evaluate any relationship between their assessment ability and preclinical skills or academic performance. The study was conducted from 2015 to 2016. Third-year students at Harvard School of Dental Medicine self-assessed their work on four preclinical practical exams: Class II amalgam preparation, Class II amalgam restoration, Class III composite preparation, and Class III composite restoration. Three faculty members graded the same preparations and restorations. The difference between the students' self-assessment and the mean faculty assessment was calculated as the student-faculty (S-F) gap. An absolute S-F gap was also calculated with absolute values of differences. A total of 71 students completed these practical exams: 36 in the Class of 2016 and 35 in the Class of 2017. All 71 self-assessments for each of the four practical exams were collected for a response rate of 100%. The results showed that the mean S-F gap ranged from 2% to 8%, and the absolute S-F gap ranged from 7% to 12%. Preclinical performance was correlated with self-assessment accuracy. Low-performing students significantly overestimated their self-assessments compared to the rest of the class. High-performing students had more accurate self-assessments and tended to underestimate themselves. Overall, these results showed that the students had room for improving the accuracy of their self-assessments.

Human leukocyte histocompatibility antigen class II-induced cytokines from human gingival fibroblasts promote proliferation of human umbilical vein endothelial cells: potential association with enhanced angiogenesis in chronic periodontal inflammation

BACKGROUND AND OBJECTIVE

The role of human leukocyte histocompatibility antigen (HLA) class II molecules on non-antigen-presenting cells has been a matter of controversy. We previously reported that HLA-II molecules on human gingival fibroblasts (GF) do not present antigens, but transduce signals into the cells, resulting in the expression of several cytokines, such as interleukin-6 (IL-6), monocyte chemoattractant protein-1 (MCP-1), regulated upon activation, normal T-cell expressed and secreted (RANTES) and IL-8. However, the exact role of these cytokines, as well as other cytokines which are potentially secreted from GF, in the pathogenesis of chronic periodontal inflammation is not fully understood. The aim of this study was to observe the effects of HLA-II-induced cytokines on the proliferation of human umbilical vein endothelial cells (HUVEC).

MATERIAL AND METHODS

Antibody-based cytokine-microarray analyses were performed to detect potential cytokines associated with angiogenesis. Next, cytokine productivity was confirmed by quantitative methods. Then, cell proliferation assay was performed to see whether these cytokines promoted the proliferation of HUVEC.

RESULTS

Besides IL-6, MCP-1, RANTES and IL-8, growth-related gene product (GRO) was newly identified as an HLA-II-induced cytokine released from GF. This was confirmed by a quantitative method. Cell culture supernatant from HLA-II-stimulated GF cultures promoted the growth of HUVEC. Addition of anti-IL-8 neutralizing antibody, anti-CXC receptor (CXCR)1 antibody and anti-MCP-1 antibody inhibited the growth of HUVEC in a dose-dependent manner, while addition of anti-GROalpha antibody did not.

CONCLUSION

The HLA-II-induced IL-8, via CXCR1, as well as MCP-1 from GF, promotes endothelial cell proliferation, which is possibly associated with enhanced angiogenesis in chronic periodontal lesions.

The involvement of IL-23 and the Th17 pathway in periodontitis

Interleukin (IL)-23 is an essential cytokine involved in expansion of the Th17 lineage, which is associated with many immune-related destructive tissue diseases. We hypothesized that the IL-23-induced Th17 pathway plays a role in periodontal pathology and examined the expression of cytokines, and related molecules, in periodontal lesions and control sites. IL-23 and IL-12 were expressed at significantly higher levels in periodontal lesions than in control sites. However, the relative expression of the IL-23 receptor compared with the IL-12 receptor beta2 was significantly higher in periodontal lesions. Moreover, IL-17 expression was significantly higher in periodontal lesions, especially in the tissue adjacent to bone destruction, than in control sites. There was no significant difference in the expression levels of IFN-gamma, an important cytokine inhibiting differentiation toward the Th17 pathway, between periodontal lesions and control sites. Together, these results suggest that the IL-23-induced Th17 pathway is stimulated in inflammatory periodontal lesions.

Adaptive response in embryogenesis: vi. Comparative microarray analysis of gene expressions in mouse fetuses

PURPOSE

Exposure of sublethal doses of ionizing radiation can induce protective mechanisms against a subsequent higher dose irradiation. This phenomenon, called radiation-induced adaptive response (AR), has been described in a wide range of biological models. We previously demonstrated the existence of AR in mice during late organogenesis. In this study, we investigated molecular mechanisms underlying AR in this model.

MATERIALS AND METHODS

Using DNA microarrays, we performed a global analysis of transcriptome regulations in adapted and non-adapted cells collected from whole mouse fetuses, after in utero exposure to priming irradiation.

RESULTS

We identified AR-specific gene modulations. Our results suggested the involvement of signal transduction and Tumor protein (p53)-related pathways in the induction of AR.

CONCLUSIONS

Our results are in agreement with previous investigations showing that AR could be dependant on p53 activity. The observed gene modulations may also have possible consequences for subsequent developmental process of the fetus. This is the first report of AR-specific modulations at the molecular level in utero, which could serve as a basis for subsequent studies aimed at understanding AR in this model and possible long-term effects.

Focal adhesion kinase mediates human leukocyte histocompatibility antigen class II-induced signaling in gingival fibroblasts

BACKGROUND AND OBJECTIVE

The role of human leukocyte antigen class II molecules on nonantigen-presenting cells has been a matter of controversy. We previously reported that human leukocyte antigen class II molecules on human gingival fibroblasts do not present antigens, but transduce signals into the cells by making a complex with antigenic peptide T-cell receptor or by stimulating cell surface human leukocyte antigen-DR molecules with human leukocyte antigen-DR antibody (L243), which mimics the formation of the human leukocyte antigen class II-antigenic peptide T-cell receptor complex, resulting in the expression of several cytokines. The aim of this study was to detect human leukocyte antigen class II-associated molecules mediating human leukocyte antigen class II-induced signals into the cells.

MATERIAL AND METHODS

Antibody-based protein-microarray analysis was performed to detect activated signaling molecules in gingival fibroblasts stimulated via human leukocyte antigen class II molecules. Then, we examined if these molecules structurally associate with human leukocyte antigen class II and actually transduce signals into the cells.

RESULTS

Stimulation of human leukocyte antigen class II on gingival fibroblasts by L243 resulted in enhanced phosphorylation of focal adhesion kinase. Focal adhesion kinase was co-immunoprecipitated with human leukocyte antigen-DR by L243. Stimulation of gingival fibroblasts with L243 induced phosphorylation of focal adhesion kinase. Luteolin, a putative focal adhesion kinase inhibitor, suppressed phosphorylation of focal adhesion kinase and dose dependently inhibited human leukocyte antigen class II-induced cytokine production.

CONCLUSION

Focal adhesion kinase is structurally associated with human leukocyte antigen-DR and mediates human leukocyte antigen class II-induced signals in gingival fibroblasts.

Recreating an esthetic smile: a multidisciplinary approach

Today's dental patients are demanding a youthful, attractive smile. The esthetic rehabilitation of patients with functionally compromised dentitions frequently involves a multidisciplinary approach. The realization of esthetic objectives in multidisciplinary cases represents a considerable clinical challenge. To a great extent, proper case selection and careful multidisciplinary treatment planning can govern the predictability of procedures. A team approach that includes the clinicians, the laboratory technician, and the patient is essential to achieve the desired results. This clinical report demonstrates a successful multidisciplinary approach to recreating an esthetic smile of a patient whose anterior maxillary dentition had been functionally and esthetically compromised by prosthetic and periodontal problems.

Polymorphism of the 5' flanking region of the IL-12 receptor beta2 gene partially determines the clinical types of leprosy through impaired transcriptional activity

BACKGROUND

Individual differences in T cell responsiveness to interleukin 12 (IL-12), resulting from inherited factors, may be responsible for differences in the intensity of cell mediated immune (CMI) responses in patients with leprosy, a disease with a wide clinical spectrum.

AIM

Polymorphisms in the 5' flanking region of the IL12RB2 gene were analysed to determine potential immunogenetic factors affecting CMI responses, using leprosy as a model.

METHODS

Polymorphisms in the 5' flanking region of IL12RB2 were examined using direct sequencing techniques, and allele frequencies between patients with lepromatous leprosy and patients with tuberculoid leprosy were compared. The effect of these single nucleotide polymorphisms (SNPs) on IL12RB2 expression was estimated using the dual luciferase reporter gene assay in Jurkat T cells.

RESULTS

Several SNPs, including -1035A>G, -1023A>G, -650delG, and -465A>G, were detected within the 5' flanking region of IL12RB2. The frequency of haplotype 1 (-1035A, -1023A, -650G, -464A) was high in the general Japanese population, but was significantly lower in lepromatous patients compared with tuberculoid patients and healthy controls. Reporter gene assays using Jurkat T cells revealed that all haplotypes carrying one or more SNP exhibited a lower transcriptional activity compared with haplotype 1.

CONCLUSION

SNPs within the 5' flanking region of IL12RB2 affect the degree of expression of this gene and may be implicated in individual differences in CMI responsiveness to mycobacterial antigens, leading to lepromatous or tuberculoid leprosy.

Mutation of Cys105 inhibits dimerization of p12CDK2-AP1 and its growth suppressor effect

p12(CDK2-AP1) (p12) is a CDK2-associated protein that negatively regulates its kinase activity. Growth arrest of normal diploid cells by contact inhibition resulted in an induction of p27(kip1) and reduction of CDK2 levels. Interestingly, we observed concomitantly in growth-arrested cells, there was a reduction of nuclear p12 and the appearance of a nuclear 25-kDa molecule (p25) recognized by anti-p12 polyclonal antibody. Biochemical analysis showed that bacterial His-tagged p12 could be converted into a dimeric p25 in a reducing agent-dependent manner, and mutating the only cysteine residue of p12 (Cys(105) --> Ala(105)) abolished the dimerization. Transient transfection of wild type p12 into U2OS cells showed a reducing agent-sensitive dimerization that was also abolished by the C105A mutation. Furthermore, reduction of p12 expression by a short interfering RNA resulted in a parallel reduction of p25. These data supports the possibility that p25 is a homodimeric form of p12 through the cysteine residue. More interestingly, transient transfection of p12 (C105A) into the normal diploid lung fibroblast CCD18LU cells resulted in a reduction of the growth-inhibitory effect of p12 and abolished the inhibitory effect of p12 on CDK2 kinase activity. In addition, we found that the C105A mutation did not alter nuclear localization of p12, but it prevented association with CDK2. Taken together, our data suggest that p12 forms a nuclear homodimers in contact inhibited normal diploid cells and dimerization of p12 is a necessary process for the growth inhibition effect by p12.

Role of helper T cells in the humoral immune responses against 53-kDa outer membrane protein from Porphyromonas gingivalis

Outer membrane protein with a 53-kDa molecular weight (Ag53) isolated from Porphyromonas gingivalis evokes strong humoral immune responses in many periodontitis patients. To examine the effects of cytokines produced by Ag53-specific Th cells on the IgG production against Ag53, we established Ag53-specific Th-cell lines from patients with early onset periodontitis and from healthy volunteers. We then developed a mixed lymphocyte culture system between Ag53-specific Th cells and auto- or allo-derived T-cell-depleted leukocytes produced from the subjects whose HLA class II haplotypes were completely matched. Interferon-gamma production was observed in all Th cell lines from patients and healthy subjects. As for Th2 type cytokines, interleukin (IL)-4, IL-5, IL-6 and IL-10 production varied greatly in Th cells regardless of the periodontal condition of the donor. Only Th cell lines with a high Th2/Th1 ratio induced Ag53-specific IgG production when cocultured with T-cell-depleted leukocytes. Thus, the difference in Th2/Th1 balance may regulate the Ag53-specific IgG production.

Interaction of the CDK2-associated protein-1, p12(DOC-1/CDK2AP1), with its homolog, p14(DOC-1R)

Human DOC-1/CDK2AP1 gene encodes a growth suppressor protein of 12kDa (p12(DOC-1/CDK2AP1)). Recently, p12(DOC-1/CDK2AP1) has been shown to associate with cell cycle proteins including CDK2 and DNA polymerase alpha/primase. It negatively regulates CDK2 activities and suppresses DNA replication. Therefore, identification of other p12(DOC-1/CDK2AP1) interacting proteins might clarify its role in the cell cycle regulation and carcinogenesis. The purpose of this study was to identify additional p12(DOC-1/CDK2AP1) interacting proteins using the yeast two-hybrid system. Using human p12(DOC-1/CDK2AP1) as a bait in a liver cDNA library screening, cDNA clones identical to human DOC-1R transcript were identified. The interaction between p12(DOC-1/CDK2AP1) and p14(DOC-1R) was verified in vitro and in cells. GST pull-down assay and immunoprecipitation experiments confirmed the interaction between the two proteins. The critical region for p12(DOC-1/CDK2AP1)'s interaction with p14(DOC-1R) was defined to amino acids 20-25 by using a series of deletion mutants as baits in the yeast two-hybrid system. Our data indicated that p12(DOC-1/CDK2AP1) could associate with its homologous protein, p14(DOC-1R).