Accuracy of a Method to Monitor Root Position Using a 3D Digital Crown/Root Model during Orthodontic Treatments.

This study aimed to assess the accuracy of a method of predicting post-movement root position during orthodontic treatment using a 3D digital crown/root model (3DCRM) created with pre-movement records of both cone-beam computed tomography (CBCT) and dental arch digital scans. Pre- and post-movement CBCT scans and dental arch digital scans of five patients who had completed orthodontic treatments were used in this study. The 3DCRM was superimposed onto the post-movement scanned dental arch to identify the post-movement root position (test method). Post-movement CBCT (referenced as the current method) served as the control to identify the actual post-movement root position. 3D-coordinate analysis revealed no significant differences between the test and current methods along the X and Y axes. However, the discrepancy on the Z axis (especially in cases of intrusion) was greater than that in all other directions for all three tooth types examined (p < 0.05). A strong positive correlation between the degree of discrepancy and the distance of tooth movement was observed on the Z axis (r = 0.71). The 3DCRM method showed promising potential to accurately predict root position during orthodontic treatments without the need for a second CBCT. However, root resorption, which affected the Z axis prediction, needs to be closely monitored using periapical radiographs to complement this method.

Indonesian Dental Students' Attitudes, Knowledge, Preparation, and Willingness to Treat HIV/AIDS Patients.

OBJECTIVE: To assess the Indonesian dental students' knowledge of HIV/AIDS in terms of transmission and oral manifestation, the attitudes toward people living with HIV/AIDS (PLWHA), the preparedness in infection control, and willingness to treat PLWHA, and assess the factors for willingness to treat PLWHA. MATERIALS AND METHODS: A modified version of a questionnaire used to assess dental students' knowledge, attitude, preparedness, and willingness to treat PLWHA in China was used. The questionnaire was cross-culturally adapted into Indonesian and had been pre-tested for face validity and test and retest reliability. The dental students from 32 dental schools in Indonesia were invited to participate in the study. RESULTS: A total of 1,280 dental students from 23 dental schools participated in the study. This study found that only 63% of students scored higher than 70% for knowledge of HIV/AIDS, and the mean score for knowledge was 15.02 (2.4). Higher than 80% of students had a positive professional attitude toward PWLHA; however, 80% of students worried about possible disease transmission in the dental office by PLWHA and 70% of students overestimated the occupational risk when treating PLWHA. The dental students had good preparedness for infection control with a mean score for preparedness of 3.19 (0.4). The mean score for willingness was 2.5 (0.9). Willingness to treat significantly differed by the type of universities, gender, age, and clinical experience. This study showed that knowledge about HIV/AIDS correlated with the willingness to treat PLWHA among dental students. CONCLUSION: Dental students who have good knowledge about HIV infection tend to have a good willingness to treat PLWHA. The knowledge would in turn affect their attitude, preparedness, and willingness to provide care for PLWHA with confidence and comfort. This study suggests that the improvement of dental training may play an important role in changing students' perception of willingness to treat PLWHA.

3D digital analysis of tooth movement with magnets and elastics in vitro.

OBJECTIVES: Magnets have many advantages in orthodontics, and our previous studies confirmed their therapeutic potential through 3D-data analysis. The aim of this study was to compare tooth movements, including rotation, obtained via magnetic and elastic forces in crowded cases in vitro. METHODS: Typodont models mimicking a crowded case were prepared. In the magnetic force-driven orthodontics (MG) group, Nd-Fe-B magnets were attached to the labial surfaces from UR4 to UL4 for attracting force, and to UR6 and UL6 for repulsing force. For the elastic force-driven orthodontic (EL) group, brackets were placed on labial surfaces from UR2 to UL2 with power-chain elastics. A NiTi archwire was used in both groups. The models were 3D scanned before and after tooth movement and exported as STL files. The pre- and post-movement STL files were superimposed. The 3D coordinates of the measurement points of the crown and root apex were obtained, and tooth displacement, 3D movements (X, Y, and Z-axis), and rotation (yaw, pitch, and roll) were calculated. Two-tailed Student's t-test was performed for comparison of the results between MG and EL groups (n = 3). RESULTS: Overall, both groups indicated similar movement and rotation to achieve the planned arch form. In the crown movement and rotation, no significant differences were observed between MG and EL groups. However, in the root movement, there was a significant difference between MG and EL groups in X and Z axis for the canines. CONCLUSIONS: Magnetic force-driven orthodontics demonstrated comparable results to elastics with less tipping movement, suggesting a potential future orthodontic modality. CLINICAL SIGNIFICANCE: This in vitro study showed the potential of magnetic force for orthodontic application. The magnetic force-driven orthodontics might provide less tipping tooth movement compared to conventional methods, such as power chains, and could be a future technique for comprehensive orthodontic treatment.

Efficacy of bisphosphonates in detection of early enamel caries using NIR fluorescence imaging and inhibition of caries progression.

NIR fluorescence imaging using bisphosphonate-Indocyanine green has been indicated for early interproximal caries detection. This study assessed diagnostic accuracy of caries detection by NIR fluorescence imaging with OsteoSense 750® (OS750) in vitro and ex vivo, and to analyze the therapeutic efficacy of a bisphosphonate (Etidronate) in inhibiting enamel caries progression in vitro. Methods: Four experiments were conducted using extracted human teeth; 1) to calculate the infiltration rate of OS750 into interproximal white spot lesions using fluorescence microscope, 2) to assess diagnostic accuracy of interproximal natural white spot lesions using desktop NIR fluorescence imaging device in vitro setting, 3) to assess diagnostic accuracy of artificially created deeper enamel carious lesion (0.5 mm~1.0 mm) using NIR fluorescence image through the head-mount display in ex vivo setting, 4) to compare the progression on the enamel caries lesions treated by Etidronate, NaF and distilled-water. Diagnostic accuracy was analyzed using sensitivity, specificity and receiver operating curves (ROC). The caries progression was calculated with micro-CT and was statistically analyzed using a two-way ANOVA and the Tukey HDS post-hoc test. Results: 1) The infiltration rate of OS750 was 101.83% ± 8.66 (Min: 90.10%, Max: 133.94%). 2) The average of sensitivity and specificity in vitro setting experiments were 86.7% ± 4.4% and 70% ± 11%, respectively. The average of area under the ROC curves (AUC) was 0.883 ± 0.059 indicating excellent performance. 3) The mean sensitivity and specificity in ex vivo setting was 82.97% ± 15% and 76.78% ± 13.27% respectively. 4) The carious lesion volume treated by Etidronate was significantly smaller at post treatment-1 (p<0.05) and treatment-2 (p<0.01) than the control. There was no significant difference in lesion volume in the Etidronate and NaF group at the time point of post treatment-1. Conclusion: This study suggests that bisphosphonates contribute to both early diagnosis of enamel caries and inhibition of caries progression.

Association between cognitive health and masticatory conditions: a descriptive study of the national database of the universal healthcare system in Japan.

Cognitive health is subject to decline with increasing numbers of lost teeth which impacts mastication. This study is a descriptive data analysis of the association between masticatory and cognitive conditions using a large database. We obtained the dental and medical records from Japan's universal healthcare system (UHCS) from the national database in 2017. The data from 94% of the Japanese population aged 65 and over is included. It is inclusive of diagnostic codes for various types of cognitive impairment, as well as dental treatment records from 2012 to 2017. The cognitive impairment group was compared to those without a diagnosis of cognitive impairment. Crude odds ratio between loss of mastication with natural teeth (exposure) and cognitive impairments (outcome) were compared. Patients who have lost masticatory function are likely to have cognitive impairment with an odds ratio of 1.89 (p<0.0001) for early elderly (aged 65-75) and 1.33 (p<0.0001) for advanced elderly (over 75). Patients who are edentulous and function with complete dentures are likely to have cognitive impairment with an odds ratio of 2.38 (p<0.0001) and 1.38 (p<0.0001), respectively. The data shows a convincing and significant result of an association between cognitive health and oral health, related to masticatory conditions.

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.

Biological efficacy of perpendicular type-I collagen protruded from TiO2-nanotubes.

The aim of this study was to evaluate the biological efficacy of a unique perpendicular protrusion of type-I collagen (Col-I) from TiO2 nanotubes (NT-EPF surface). We hypothesized that the NT-EPF surface would play bifunctional roles in stimulating platelet-mediated fibroblast recruitment and anchoring fibroblast-derived Col-I to form a perpendicular collagen assembly, mimicking the connective tissue attachment around natural teeth for the long-term maintenance of dental implants. Ti surface modification was accomplished in two steps. First, TiO2 nanotubes (NT) array was fabricated via anodization. Diameters and depths of NTs were controlled by applied voltage and duration. Subsequently, an electrophoretic fusion (EPF) method was applied to fuse Col-I into nanotube arrays in a perpendicular fashion. Surface wettability was assessed by contact angle measurement. The bioactivity of modified TiO2 surfaces was evaluated in terms of NIH3T3 fibroblast attachment, platelet activation, and collagen extension. Early attachment, aggregation, and activation of platelets as well as release of platelet-related growth factors were demonstrated on NT-EPF surfaces. Platelet-mediated NIH3T3 cells migration toward NT-EPF was significantly increased and the attached cells showed a typical fibrous morphology with elongated spindle shape. A direct linkage between pseudopod-like processes of fibroblasts to NT-EPF surfaces was observed. Furthermore, the engineered EPF collagen protrusion linked with cell-derived collagen in a perpendicular fashion. Within the limitation of this in vitro study, the TiO2 nanotube with perpendicular Col-I surface (NT-EPF) promoted better cell attachment, induced a strong platelet activation which suggested the ability to create a more robust soft tissue seal.

Effect of Magnet Position on Tipping and Bodily Tooth Movement in Magnetic Force-Driven Orthodontics.

The goal of our study is to launch magnetic force-driven orthodontics. This continuous study investigated the influence of magnet position on tipping and bodily tooth movement, using 3D printing technology and digital analysis. Orthodontic typodont models (TMs) for space-closure were 3D printed to mimic maxillary central incisors. Nd-Fe-B magnets were placed in the middle third (Model-M), and the cervical third (Model-C), of the tooth. TMs, before and after movement, were digitally scanned and superimposed. The 3D digital coordinates (X, Y, and Z axes), and rotations (yaw, pitch, and roll) of the tooth crown and root, were calculated and compared between the two magnet position settings. Model-M showed higher rates of movement, but more rotation than Model-C (p < 0.01). The root apex of Model-M moved in the opposite direction of the crown (R = -0.29), indicating tipping movement. In contrast, the crown and root apex moved in the same direction (R = 0.56) in Model-C, indicating bodily movement. These patterns were confirmed in a typodont model of a moderate crowding case. The results validated that modifying the magnet position increased the amount of bodily tooth movement, and decreased rotation/tipping in an ex vivo setting.

Trans-trigeminal transport of masseter-derived neprilysin to hippocampus.

OBJECTIVE: To show the possible occurrence of exosomal transport of neprilysin from masseter muscle to hippocampus via trigeminal nerve in the living mouse. DESIGN: Mouse C2C12 myotube-derived exosomes were labeled with near-infrared (NIR) dye and injected into the masseter muscle to track their fluorescence from masseter muscle to hippocampus via trigeminal nerve. A plasmid vector encoding green fluorescent protein (GFP)-tagged neprilysin (GFP-neprilysin) was transfected into masseter muscle of C57BL/6 J mice. Expression of mRNA and encoded protein of the transgene was identified in masseter muscle, trigeminal nerve and hippocampus by RT-PCR and Western blot, respectively. RESULTS: Peak of exosomal NIR in masseter muscle at time 0 rapidly reduced at 3 h and 6 h along with the subsequent increases in trigeminal nerve and hippocampus. Expression of GFP-neprilysin mRNA was detected in masseter muscle, but not trigeminal nerve and hippocampus. On the other hand, the corresponding protein of GFP-neprilysin was identified in the three tissues on day 3 after transfection into masseter muscle as a single band on Western blots with anti-GFP and anti-neprilysin antibodies. CONCLUSION: The appearance of GFP-neprilysin protein in trigeminal nerve and hippocampus without a corresponding mRNA expression indicated the protein's origin from the masseter muscle. Concomitant migration of NIR-exosomes from masseter muscle to hippocampus via trigeminal nerve suggested the possible occurrence of exosomal transport of neprilysin.

Antibiotic prescribing practices in periodontal surgeries with and without bone grafting.

BACKGROUND: The prevention of postoperative infection is often the basis for antibiotic prescription; however, the risks of unwarranted antibiotics and lack of guidelines for procedures involving bone grafts creates additional difficulty in decision making for practitioners. This study aims to evaluate practices in antibiotics prescribed for periodontal surgeries with and without bone grafting and acceptability of guidelines. METHODS: An anonymous survey was distributed to periodontists via the California Society of Periodontists e-mail listserv. The survey questioned prescribing practices for periodontal procedures, prescribing rationale, demographic and dental practice information, and acceptability of guidelines. Results were analyzed using McNemar tests and logistic regression. RESULTS: Practitioners were significantly less likely to prescribe antibiotics for traditional periodontal surgeries without bone grafting compared with socket preservation, guided tissue regeneration, guided bone regeneration, and sinus augmentation (P < 0.0001). Practitioners were significantly more likely to prescribe antibiotics with more complex bone grafting such as guided bone regeneration and sinus augmentation compared with socket preservation (P < 0.0001). The most common rationale for prescribing antibiotics with bone grafting was to decrease the chances of developing an infection. Seventy-five percent of practitioners reported they would follow guidelines for antibiotic prescription if they were developed by the American Academy of Periodontology. CONCLUSIONS: Practitioners are more likely to prescribe antibiotics with bone grafting and as complexity of the bone grafting procedure increases. Based on these results, the low incidence of infection in periodontal surgery cited in the literature, and willingness of practitioners to adopt guidelines, the establishment of evidence-based guidelines would be of benefit to the periodontal practicing community.

3D digital analysis of magnetic force-driven orthodontic tooth movement.

With the introduction of rare earth magnets like neodymium-iron-boron (NdFeB), it has become possible to produce small magnets with high forces, necessary for its usage in the field of dentistry, such as for orthodontic tooth movement. The ultimate goal of this project is to establish magnetic force-driven orthodontic treatment as a future treatment modality for comprehensive orthodontic treatment. In order to utilize magnets for orthodontic treatment, we must first understand the characteristics of tooth movement created by magnetic forces. In this study, we aimed to digitally assess the efficacy of magnetic attraction and repulsion forces by means of a 3D digital analysis of movement (distance, direction, angulation and duration) and rotation (yaw, pitch and roll) of the crown and root of teeth in an ex vivo typodont model. We performed space closure and space gain treatment of maxillary central incisors (n = 30) and analyzed the movement and rotation of the teeth and root apex with 3D digital analysis. The results of the typodont model indicated significant differences on amount, speed and rotation of tooth and root movement created by magnetic attraction and repulsion forces. We also mimicked a moderate crowding typodont case and successfully treated it with a combination of attraction and repulsion magnetic forces. The moderate crowding case utilized magnets and a titanium archwire to guide the planned tooth movements and prevent undesired or unexpected movement. Further ex vivo experiments and considerations for biosafety will be necessary to investigate magnet force-driven orthodontics as a future modality of orthodontic treatment.

Establishment of perpendicular protrusion of type I collagen on TiO2 nanotube surface as a priming site of peri-implant connective fibers.

Natural teeth are supported by connective tissue collagen fibers that insert perpendicularly in the tooth cementum. Perpendicular insertion plays an important role in the maintenance of the junction between the oral epithelium and the periodontal connective tissue. Most titanium dental implant surfaces have no micro or macro structure to support perpendicularly oriented collagen attachment. Without this tight biologic seal to resist bacterial invasion and epithelial downgrowth, progressive bone loss in peri-implantitis is seen around dental implants. The purpose of this study was to establish the perpendicularly oriented collagen attachment to titanium oxide nanotube (TNT), and to assess its binding stability. TNT was prepared on the titanium-surface by anodization. Scanning electron microscopy (SEM) showed a regularly aligned TNT with an average 67 nm-diameter when anodized at 30 V for 3 h. Subsequently, collagen type I (CoI) was electrophoretically fused to anodic TNT in native polyacrylamide gel system where negatively charged CoI-C term was perpendicularly navigated to TNT. SEM and atomic force microscopy (AFM) were used to analyze CoI on the TiO2 and TNT surface. Several tens of nanometers of CoI protrusion were recorded by AFM. These protrusions may be long enough to be priming sites for cell-secreted CoI. CoI laid parallel to the titanium surface when fused by a chemical linker. Binding resistance of CoI against drastic ultrasonication was measured by Fourier-transform infrared spectroscopy attenuated total reflection (FTIR-ATR). The electrophoretically fused CoI in the titanium nanotube (TNT-CoIEPF) showed the significantly greatest binding resistance than the other groups (P < 0.01, a 1-way ANOVA and Tukey HSD post hoc test). Furthermore, TNT-CoIEPF surface rejected epithelial cell stretching and epithelial sheet formation. Chemically linked horizontal CoI on titanium oxide (TiO2) facilitated epithelial cell stretching and sheet formation.

Knowledge and Practice of Oral Cancer Screening in Teaching Faculty-Comparison of Specialty and Year of Clinical Experience.

The purpose of this study was to assess the knowledge, practice, confidence, and perceived barriers to oral cancer screening among teaching faculty in Japan. Results were compared by specialist as well as years of clinical experience. A 25-question survey was used to assess the oral cancer screening practices of faculty dentists at Iwate Medical University, School of Dental Medicine, the only dental school located in the northeast (Tohoku) region of Japan. The study was approved by the Institutional Review Board of Iwate Medical University. The response rate was 83% (n = 110, 71.8% were male). This survey revealed that only 43.6% of the dentists performed oral cancer screening frequently (always or usually) at the initial appointment, and there was no significant differences between specialists and clinical experience. Visual inspection of the oral cavity was the primary screening method, but the frequency and content of the examination (TMJ and tonsil) was significantly different between specialties. A history of cancer and tobacco use motivated providers to perform an examination and was significantly different between various specialists and clinically experienced providers. In contrast, HPV and alcohol consumption were a weak motivator. The confidence level of providers on their examination knowledge/skills was poor, especially among junior faculty. More than 80% of junior faculty indicated a lack of knowledge/skills as a major barrier.

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.

Epithelial cell adhesion efficacy of a novel peptide identified by panning on a smooth titanium surface.

Epithelial attachment via the basal lamina on the tooth surface provides an important structural defence mechanism against bacterial invasion in combating periodontal disease. However, when considering dental implants, strong epithelial attachment does not exist throughout the titanium-soft tissue interface, making soft tissues more susceptible to peri-implant disease. This study introduced a novel synthetic peptide (A10) to enhance epithelial attachment. A10 was identified from a bacterial peptide display library and synthesized. A10 and protease-activated receptor 4-activating peptide (PAR4-AP, positive control) were immobilized on commercially pure titanium. The peptide-treated titanium showed high epithelial cell migration ability during incubation in platelet-rich plasma. We confirmed the development of dense and expanded BL (stained by Ln5) with pericellular junctions (stained by ZO1) on the peptide-treated titanium surface. In an adhesion assay of epithelial cells on A10-treated titanium, PAR4-AP-treated titanium, bovine root and non-treated titanium, A10-treated titanium and PAR4-AP-treated titanium showed significantly stronger adhesion than non-treated titanium. PAR4-AP-treated titanium showed significantly higher inflammatory cytokine release than non-treated titanium. There was no significant difference in inflammatory cytokine release between A10-treated and non-treated titanium. These results indicated that A10 could induce the adhesion and migration of epithelial cells with low inflammatory cytokine release. This novel peptide has a potentially useful application that could improve clinical outcomes with titanium implants and abutments by reducing or preventing peri-implant disease.

Effectiveness of a Flipped Classroom in Learning Periodontal Diagnosis and Treatment Planning.

The aim of this study was to assess whether a flipped classroom was an effective model for dental students to learn periodontal diagnosis and treatment planning (DTP). Participants were all third-year students in three academic years (2015-17) at Harvard School of Dental Medicine: two groups that experienced the flipped classroom (Classes of 2017 and 2018), and a control group (Class of 2019) that received the same content in traditional lecture format. All three groups completed a DTP knowledge quiz before and after the educational experience; the flipped classroom groups also completed pre and post surveys of their opinions about flipped classrooms. The flipped classroom group received a 23-minute video and corresponding PowerPoint presentation to view on their own time. In class, these students were divided into groups to diagnosis and treatment plan cases and discuss them with the instructor. Of 71 students in the two flipped classroom groups, 69 pre and post quizzes were returned (response rate 97%), and 61 pre and post surveys were returned (response rate 86%). Of 35 students in the lecture group, 34 completed pre and post quizzes (response rate 97%). The mean pre scores on the knowledge quiz in the flipped classroom groups and the conventional lecture group were 64% and 54%, respectively. After the DTP education, students' quiz scores improved in all three groups, but only the difference in the flipped classroom groups was statistically significant (p<0.01). After the flipped classroom session, 84% of the students agreed or strongly agreed that this methodology was effective for learning periodontal DTP, and 90% agreed or strongly agreed they understood the fundamentals of periodontal DTP-both increases over their pre survey scores. Overall, this flipped classroom model was effective in educating students on periodontal DTP and was well received by the students.

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 Effect of a Toothbrush Handle Design in Combating Microbial Contamination.

OBJECTIVES: This study aims to assess the difference in microbial contamination of a toothbrush with a smooth handle versus a toothbrush with a grooved handle design. METHODS: Twenty-six volunteers were randomized into two groups. The first group used a smooth handle toothbrush for two months, followed by a grooved handle toothbrush for two months. The second group had the order reversed. Following the two-month use, the toothbrushes were submitted for microbial analysis. Effect size, as well as Wilcoxon signed-rank test were used to calculate the differences between total colony count, bacterial DNA, and endotoxin levels from the two toothbrush handle types. RESULTS: There was no significant difference in colony count between the smooth (mean 580 CFU/mL, SD 1,684 CFU/mL) and grooved (mean 19,059 CFU/mL, SD 80,972 CFU/mL) handles (p = 0.12). Total DNA count was significantly less (p = 0.01) on the smooth handle (mean 68,038 RFU/mL, SD 81,659) compared to the grooved handle (mean 209,312 RFU/mL, SD 257,169 RFU/mL). Endotoxin levels were significantly less (p = 0.01) on the smooth handle (mean 0.16 EU/mL, SD 0.30 EU/mL) compared to the grooved handle (mean 0.43 EU/mL, SD 0.49 EU/mL). CONCLUSIONS: The smooth handle toothbrush had significantly less bacterial contamination compared to the grooved handle toothbrush, as measured by total DNA count and endotoxin levels.

Dental Students' Perceptions of Digital Assessment Software for Preclinical Tooth Preparation Exercises.

Objective self-assessment is essential to learning and continued competence in dentistry. A computer-assisted design/computer-assisted manufacturing (CAD/CAM) learning software (prepCheck, Sirona) allows students to objectively assess their performance in preclinical prosthodontics. The aim of this study was to evaluate students' perceptions of CAD/CAM learning software for preclinical prosthodontics exercises. In 2014, all third-year dental students at Harvard School of Dental Medicine (n=36) were individually instructed by a trained faculty member in using prepCheck. Each student completed a preclinical formative exercise (#18) and summative examination (#30) for ceramometal crown preparation and evaluated the preparation using five assessment tools (reduction, margin width, surface finish, taper, and undercut) in prepCheck. The students then rated each of the five tools for usefulness, user-friendliness, and frequency of use on a scale from 1=lowest to 5=highest. Faculty members graded the tooth preparations as pass (P), marginal-pass (MP), or fail (F). The survey response rate was 100%. The tools for undercut and taper had the highest scores for usefulness, user-friendliness, and frequency of use. The reduction tool score was significantly lower in all categories (p<0.01). There were significant differences in usefulness (p<0.05) and user-friendliness (p<0.05) scores among the P, MP, and F groups. These results suggest that the prepCheck taper and undercut tools were useful for the students' learning process in a preclinical exercise. The students' perceptions of prepCheck and their preclinical performance were related, and those students who performed poorest rated the software as significantly more useful.

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.