A microanalysis of expert-student dialogue videos: Supporting preparation and learning for clinical competence assessment.

INTRODUCTION: The aim of this qualitative study was to analyse students' perceptions and impact of using a novel video genre designed to support their learning and preparation for a clinical competence assessment. The videos demonstrate expert-student dialogue (ESD) of authentic, one-on-one discourse between the teacher and student, relating to the case presentation and self-evaluation of the assessment. METHODS: Students who were about to perform a competence assessment were invited to participate in the study. Students were asked to watch a relevant ESD video they had not previously had access to, which showed the examiner-examinee dialogue relating to a peer's tooth preparation for the competence assessment. Immediately after watching the video, a video simulated recall approach was performed to analyse students' perceptions. Thematic analysis was performed to induce relevant themes. RESULTS: Five themes were identified: analysis and judgement, observational learning from expert dialogue, observational learning from student dialogue, self-efficacy and empathy. Positive responses from interviews suggested high cognitive engagement with this video genre with an affective component that was also valued as an informative learning resource. Students reported the video could stimulate them to think, make it easier to remember knowledge, avoid errors observed, and gain insights into assessment process and examiner's expectations. Empathy was also reported towards the examinee in the video. CONCLUSIONS: The ESD videos facilitated students' active and analytical thinking as well as improved their assessment preparedness. This video genre has shown how observing ESD can support students' learning and preparation for a clinical competence assessment.

The relation of online learning analytics, approaches to learning and academic achievement in a clinical skills course.

INTRODUCTION: This study examined relationships of students' access of e-learning (learning analytics) for a healthcare psychomotor skills course, approaches to learning (R-SPQ-2F psychometric) and academic achievement (summative examination results). An understanding of the relationships may help in supporting students learning. METHODS: Two consecutive cohorts of 5th year dental students were asked to complete the R-SPQ-2F questionnaire and permission to access data of online videos and associated quizzes and two summative written examination results were examined. The summative assessments were an OSCA and a written-paper question both in prosthodontics. Multiple linear regression and correlation analysis were performed. RESULTS: Students (n=98) performed a total of 10470 video access events and 7714 attempts in online quizzes. Deep learning approach was the strongest predictor variable (ß=0.270; P=.004) on written-paper question result. While video and quiz access were moderately correlated (r=0.600; P<.001) to each other, video access was not a significant predictor to either of the examination results. Quiz access was negatively associated with academic achievement for the written-paper question results (ß=-0.349; P<.001). CONCLUSIONS: Only deep approach to learning appeared to be relevant for the written-paper question examination grades. Conversely, the number of video and quiz access did not relate to either examination results. This suggests e-learning access and examinations do not appear to relate under the conditions explored. Other attributes of learning management access may need to be explored to determine if access to learning management systems may be useful in offering remedial support to students.

An exploration of student access to a learning management system-challenges and recommendations for educators and researchers.

INTRODUCTION: This study examined student access to online resources of a faculty's learning management system (LMS). Issues relating to current e-learning resources usage were identified and formed the basis for recommendations to help assist stakeholders in teaching, learning and research. METHODS: Learning analytics from four cohorts of undergraduate dental students were extracted from the database of a LMS spanning between 2012 and 2016. Individual datasets were combined into one master file, re-categorised, filtered and analysed based on cohort, year of study, course and nature of online resource. RESULTS: A total of 157,293 access events were documented. The proportion of administrative to learning data varied across cohorts, with oldest cohort having the highest ratio (82:18) in their final year and most recent cohort having a ratio of 33:67 in their 4th year demonstrating a higher proportion to learning. Seven Learning domains were identified in the access data: access to problem-based learning resources was the highest and next was fixed prosthodontics videos. The prosthodontics discipline had the highest access across the curriculum while some others had very limited or even no learning access events. CONCLUSION: A number of limitations have been identified with the analytics and learning resources in this LMS and engagement with learning resource provision. More detailed data capture of access use and unique identifiers to resources as well as keyword tagging of the resources are required to allow accurate mapping and support of students learning. Moreover, motivation or nudging of students behaviour to more actively engage with learning content needs exploration.

A Systematic Review of Amalgam Bonded Restorations: In vitro and Clinical Findings.

AIM: This article aims to systematically review the evidence reporting on physical properties of bonded amalgam, its clinical performance, and implications. MATERIALS AND METHODS: An electronic search in "Medline" (search term: Amalgam and Dentin bonding) from 1987 to 2013 yielded 465 publications out of which 170 articles were selected for the analysis. Data were extracted relating to the bond strength of amalgam to dentin, microleakage, postoperative sensitivity, and longevity of bonded amalgam restorations. RESULTS: A total of 129 in vitro studies out of 170 articles showed high bond strengths with filled adhesive resins and light-cured adhesives, in particular Amalgambond plus and Optibond adhe-sives. Thickness of bonding agent, type of alloy, and thermo-cycling showed inconclusive outcomes between bonded and nonbonded amalgam restorations. Majority of studies reported reduced microleakage when dentin bonding agents and resin-modified glass ionomer cements (RM-GICs) were used with amalgam. However, water stored, thermocycled, and spherical amalgam alloys resulted in higher microleakage. While bonded amalgam facilitated the retention of large restorations, reduction in postoperative sensitivity was not consistently observed between bonded and nonbonded amalgam restorations. CONCLUSION: While bonded amalgam restorations reduce the need for mechanical retention conserving tooth structure and reducing the adverse effects of microleakage, there is lack of consistent evidence across all outcome domains to advocate the benefit of bonding of all amalgam restorations. Despite this, it can be considered the material of choice for large restorations and bonding enhances retention in vitro which can be considered beneficial clinically. CLINICAL SIGNIFICANCE: The use of adhesives to bond amalgam to the tooth structure offers potential advantages, as it helps in conservative cavity preparation without compromising the retention to tooth, making it a material of choice in large posterior restorations.

Bilateral Condylar Hyperplasia-Nonsurgical Management: A Clinical Report.

Background: Patients present with malocclusions in the form of bilateral open bite with functional and esthetic challenges. These are particularly so whereby these are acquired through growth anomalies that create a change in the occlusal status whereby a patient has to adapt to the challenge of the occlusal change. While surgical intervention is a considered option to correct such changes, not all patients are willing to endure the consequences of this intervention and as such this report presents a conservative minimally invasive approach. Aim: This clinical report demonstrates a nonsurgical approach in the management of a patient with bilateral metabolically active condylar hyperplasia. Case report: The patient presented with a bilateral open bite with occlusal contacts only present on her second molars. The severity of the open bite was reported to be recently progressing and getting worse. This condition had impaired her chewing function and quality of life over an 8-year period. Bone scintigraphy was performed and metabolically active bilateral condylar hyperplasia was diagnosed. The patient refused surgical intervention and instead a conservative overlay denture was prescribed, which successfully restored her function and esthetics. Conclusion: Removable overlay dentures can be a relatively simple and effective treatment option for patients presenting with newly acquired bilateral open bites to give a functional and esthetic outcome. Clinical significance: This clinical report shows the conservative management of bilateral condylar hyperplasia with a simple removable overlay appliance. The occlusion has stabilized and the patient functions well. Keywords: Bone scintigraphy, Condylar hyperplasia, Open bite, Overlay denture.

Antibacterial Effect of Silver Diammine Fluoride on Cariogenic Organisms

AIM: To screen the possible antimicrobial activity of a range of clinically used, silver-based compounds on cariogenic organisms: silver diammine fluoride (SDF), silver fluoride, and silver nitrate. MATERIALS AND METHODS: Preliminary screening disk-diffusion susceptibility tests were conducted on Mueller-Hinton agar plates inoculated with Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces naeslundii, organisms known to be cariogenic. In order to identify which component of the silver compounds was responsible for any antibacterial (AB) effect, and to provide controls, the following were also investigated at high and low concentrations: sodium fluoride, ammonium fluoride, ammonium chloride, sodium fluoride, sodium chloride, and sodium nitrate, as well as deionized water as control. A volume of 10 pL of a test solution was dispensed onto a paper disk resting on the inoculated agar surface, and the plate incubated anaerobically at 37°C for 48 hours. The zones of inhibition were then measured. RESULTS: Silver diammine fluoride, silver fluoride, silver nitrate, and ammonium fluoride had significant AB effect (p < 0.05) on all three test organisms, although ammonium fluoride had no effect at low concentration; the remaining other compounds had no effect. CONCLUSION: Silver ions appear to be the principal AB agent at both high and low concentration; fluoride ions only have an AB effect at high concentration, while ammonium, nitrate, chloride and sodium ions have none. The anticaries effect of topical silver solutions appears restricted to that of the silver ions. CLINICAL SIGNIFICANCE: Silver compounds, such as SDF, silver fluoride, and silver nitrate have AB effect against cariogenic organisms and these may have clinical impact in arresting or preventing dental decay. Sodium fluoride did not have AB effect under the conditions tested.

Oral Rehabilitation of Young Adult with Amelogenesis Imperfecta.

BACKGROUND: Amelogenesis imperfecta is a heterogeneous group of hereditary disorders that affect the enamel formation of the primary and permanent dentitions while the remaining tooth structure is normal. Appropriate patient care is necessary to prevent adverse effects on dental oral health, dental disfigurement, and psychological well-being. AIM: This clinical report presents a 27-year-old Chinese male with amelogenesis imperfecta (AI) and his restorative management. CASE REPORT: This clinical report presents a 27-year-old Chinese male with AI and his restorative management. Extraoral examination showed a skeletal class III profile and increased lower facial proportion. Intraorally, all the permanent dentition was hypoplastic with noticeable tooth surface loss and a yellow-brown appearance. This was complicated with a mild maloc-clusion and food packing on his posterior teeth. The patient wanted to improve his appearance and masticatory efficiency. Orthodontic treatment was performed to treat the mild malocclu-sion and create physiological interproximal spacing to minimize tooth preparation and facilitate oral hygiene. CONCLUSION: This report demonstrates how a multidisciplinary approach for the management of AI can achieve a predictable, functional, and esthetic outcome. Orthodontic treatment facilitated a conservative prosthodontic treatment outcome by selectively increasing interproximal space, minimizing tooth preparation, correcting posterior bilateral cross-bite, as well as an anterior reverse overjet and derotation of the canines. CLINICAL SIGNIFICANCE: This case report demonstrates the effective restoration of AI using a multidisciplinary approach to overcome crowding using a relatively conservative approach.

Zirconia Surface Treatments for Resin Bonding.

PURPOSE: To evaluate the bond strength of resin to zirconia treated with different surface conditioning methods. MATERIALS AND METHODS: Sintered zirconia was surface treated to create 7 groups. Ceramic liner (L) was fired onto three groups of zirconia and subsequently received the following treatments: hydrofluoric acid etching (L/ HFE), alumina particle abrasion (L/APA), and alumina particle abrasion with hydrofluoric acid etching (L/APAHFE). All three groups were silane treated immediately prior to bonding. Two other zirconia groups received alumina particle abrasion with and without silane coupling (AP-S and AP). Another group underwent selective infiltration etching, in which the specimens received porcelain powder firing, ultrasonic etching with HF for 15 min, then rinsing under running water for 15 min, followed by silane treatment (SIE). The control group was zirconia as-sintered (ZAS). Twenty composite resin cylinders were luted to each group with a resin cement. Each group was divided into two subgroups (n=10) and subjected to 2 storage conditions: 24 h water storage or 21 days with 6000 thermocycles between 5°C and 55°C. Shear bond strength testing (SBS) was performed, followed by statistical analysis of the results using one-way ANOVA (p < 0.05). RESULTS: After 21 days of thermocycling, AP and ZAS groups spontaneously debonded prior to testing. The remaining groups showed a decrease in mean shear bond strength between 11.7% and 58.5% after thermocycling, except the L/HFE group, which increased by 11.7%. L/HFE showed the highest bond strength at both test intervals, and at 21 days was significantly higher than that of the AP-S and L/APA-HFE groups, which in turn were higher than that of the L/APA group, which was higher than that of the SIE group (p < 0.05). CONCLUSION: The etched, fired ceramic liner with silane treatment provided the strongest and most durable bond under the conditions tested. Alumina particle abrasion degraded the durability of the ceramic liner. Alumina particle abrasion, as-sintered zirconia, and SIE did not provide durable bond strengths.

Impact of complications of single tooth restorations on oral health-related quality of life.

OBJECTIVE: To compare oral health-related quality of life (OHRQoL) among subjects who received implant-supported crowns (ISC) and 2-unit cantilevered resin-bonded bridges (cRBB) in a bounded single tooth space (BSTS) after at least 5 years and to investigate factors associated with their OHRQoL. METHODS: A case-control study among 78 subjects who received ISC or cRBB rehabilitation at a teaching hospital (39 ISCs and 39 cRBBs). OHRQoL was measured using the Oral Health Impact Profile (OHIP-49) and compared between treatment modality. Variations in OHIP scores with respect to "minor complications" (repair of the original "survived" restorations) and "major complications" (replacement of "failed" restorations); and number of complications were determined in bivariate and multivariate analyses (negative binominal regression) controlling for socio-demographic and clinical factors. RESULTS: Oral Health Impact Profile scores were similar among those who received ISC and cRBB (P = 0.53). Among subjects with complicated restorations, those with major complications reported significantly higher OHIP scores (poorer OHRQoL) than those with minor complications (P = 0.02). Subjects who experienced multiple complications had significantly higher OHIP scores (poorer OHRQoL) than those with a single complication (P = 0.04). In regression analyses (which considered OHIP scores of those with complications), the nature of complications (P < 0.01), treatment modality (P = 0.04), and gender (P = 0.02) emerged as significant factors. CONCLUSION: In the rehabilitation of a BSTS patients, OHRQoL was similar irrespective of treatment modality (ISC or cRBB). Among those who experienced complications their OHRQoL was associated with the nature of complications, treatment modality and gender.

Effect of surface treatments of zirconia ceramics on the bond strength to resin cement.

PURPOSE: The purpose of this in vitro study was to evaluate the bond strength of a resin luting cement to zirconia surfaces that had received two novel surface pretreatment methods: etching of a pre-fired overglaze or paste liner on the zirconia substrate. MATERIALS AND METHODS: Fully sintered zirconia disks were assigned to 6 groups according to the surface pretreatment: firing of 2 layers of paste liner which was then etched with hydrofluoric acid and treated with silane (Liner group); firing of 2 layers of overglaze which were then etched with hydrofluoric acid and treated with silane (glaze group); Rocatec treatment and silane application (Rocatec group); Rocatec treatment followed by ultrasonic cleaning and silanization (ultrasonic-Rocatec group); sandblasted with alumina (alumina group); as-sintered with no pretreatment (control group). Twenty composite resin cylinders were bonded to each group with Panavia F 2.0. Each group was further divided into 2 subgroups (n = 10) for 2 different storage conditions: 24 h water storage or 3 weeks water storage plus 6000 thermocycles between 5°C and 55°C. The shear bond strength was then determined. Statistical analyses with two-way ANOVA were conducted; the level of significance was set at p < 0.05. RESULTS: At 24 h, the shear bond strength values of all groups except the control showed no statistically significant difference. After artificial aging, the mean bond strength of all groups dropped, but the decrease in the glaze group was not statistically significant. The glaze group showed the highest shear bond strength. However, that was not statistically different from the liner or the Rocatec group without ultrasonic cleaning (p < 0.05). All the control specimens debonded spontaneously after aging. Ultrasonic cleaning after Rocatec treatment caused a reduction in shear bond strength, but the difference was not statistically significant. CONCLUSION: Both the fired paste liner and overglazed ceramic treated zirconia surfaces provided a strong and durable bond to resin cement under the conditions tested.

Posterior two-unit cantilevered zirconia resin-bonded fixed partial dentures: A 3-year prospective single-arm clinical trial.

OBJECTIVES: To evaluate the longevity of cantilevered zirconia-based resin-bonded fixed partial dentures (RBFPDs) in replacing missing posterior teeth, as well as the quality of life and patient satisfaction experienced by those receiving zirconia RBFPDs. METHODS: A prospective single-arm uncontrolled clinical trial was conducted to replace one or more missing premolars or molars with a span of 5 to 8 mm using cantilevered zirconia RBFPDs. Thirty-six participants with 40 prostheses were recruited and underwent a 3-year clinical evaluation. The retainer designs included a minimum thickness of 0.8 mm, a minimum of 200° circumferential wraparound with an occlusal bar, and a connector dimension of 3 × 3 mm. Patient-reported outcomes, including patient satisfaction and Oral Health Impact Profile (OHIP), were assessed. RESULTS: The average age of participants was 45.8 years, and 72.5 % were women. The success rate of the posterior zirconia RBFPDs was 76.2 %, with an estimated mean success duration of 46.1 months. The survival rate was 88.1 %, with an estimated mean survival duration of 49.4 months. Participants were highly satisfied with the treatment, achieving an average satisfaction score of 80.8 ± 11.9. Participants' total OHIP scores decreased from 52.3 to 39.6 after 3 years, indicating a significant improvement in oral health-related quality of life (P = 0.009). CONCLUSIONS: After 3 years, a moderately high survival rate and favourable patient-reported outcomes of posterior cantilevered zirconia RBFPDs were achieved. Therefore, it can be recommended as a conservative treatment option to replace missing posterior teeth, provided that retainer design considerations are taken into account. CLINICAL SIGNIFICANCE: Cantilevered zirconia RBFPDs for posterior teeth can serve as a conservative treatment option that is both aesthetically pleasing and biocompatible. It offers a more cost-effective alternative compared to dental implants, which are often prohibitively expensive for the majority of patients. This approach has the potential to greatly improve patient-reported outcomes.

Longevity of implant crowns and 2-unit cantilevered resin-bonded bridges.

OBJECTIVE: To compare "survival" and "success" of implant-supported crowns (ISC) and tooth-supported 2-unit cantilevered resin-bonded bridges (cRBB) in the rehabilitation of a bounded single tooth space (BSTS), after an observation period of ≥5 years. METHODS: A case-control study among subjects who received ISC or cRBB rehabilitation at a teaching hospital. The (i) survival (retention in mouth) and (ii) success (absence of complications requiring intervention) for the ISCs and cRBBs were compared (overall, supporting structures and that of the prostheses). Rates of survival and success were compared using log-rank statistics. Prevalence of survival and success (categories) were compared by chi-square/Fisher's exact test. RESULTS: Seventy eight subjects participated in this study (39 ISC and 39 cRBB cases). Both had a mean observation time exceeding 100 months, P > 0.05. ISCs and cRBBs had similar survival rates: overall (P = 0.96), supporting structures (P = 0.14) and prostheses (P = 0.44) There was a significant difference in the rate of overall success between ISCs and cRBBs (P = 0.03), specifically with respect to the success rate of the supporting structures (P = 0.03). There was also a significant difference in the prevalence of supporting structures categorized as a "success": ISCs (69.2%) and cRBBs (89.7%), P = 0.03. Biological complications of supporting structures were more common among ISCs (25.6%) compared with cRBBs (7.7%), P = 0.03. CONCLUSION: Implant-supported crowns and cRBBs in the rehabilitation of a BSTS survive similarly after at least 5 years. However, cRBBs had a higher success rate and were more frequently categorized as successful than ISCs. Notably, there were fewer biological complications of cRBBs supporting structures than ISCs.

Comparison of the colour accuracy of a single-lens reflex camera and a smartphone camera in a clinical context.

OBJECTIVES: This study aimed to investigate the colour accuracy of digital photographs captured by a single-lens reflex (SLR) camera and a smartphone camera in a clinical setting. METHODS: Dentate subjects were recruited, and their maxillary anterior teeth were photographed along with a colour target and a dental shade guide. There were eight groups: Group 1: SLR camera with a 100 mm macro-lens and a ring-flash (SLRC); Group 2: SLRC with a polarizer; Group 3: SLRC with white-balance calibration; Group 4: SLRC with a polarizer and white-balance calibration. Groups 5 to 8 were similar to Groups 1 to 4, except a smartphone camera and an external light source (SC) were used. The CIE LAB coordinates of the colour target, shade guide, and centre of the maxillary right central incisor (tooth 11) in the digital photographs were retrieved. The colour difference ΔE=[(ΔL*)2+(Δa*)2+(Δb*)2]1/2 to the reference colour coordinates or the reading of the dental spectrophotometer was calculated. The results were analysed by the Kruskal-Wallis test at α=0.05 with Bonferroni correction. RESULTS: Thirty-nine subjects were photographed. SLRC with a polarizer showed the largest ΔE in this study (P<0.001). When capturing tooth 11, SLRC with calibrated white-balance resulted in the smallest ΔE in this study (P<0.001), and the use of a polarizer and/or calibrated white-balance did not result in a smaller ΔE than that of SC alone (P>0.001). CONCLUSION: Calibration for white-balance is recommended for the SLRC. The use of a polarizer does not show an improvement in colour accuracy. SC alone may be sufficient for intraoral photography. CLINICAL SIGNIFICANCE: When capturing intraoral photography using a single-lens reflex camera, it is recommended to calibrate the white-balance. The use of a polarizer does not significantly improve colour accuracy. However, a smartphone camera with an external light source can serve as a viable alternative.

Effect of contamination and decontamination on adhesion of a resin-modified glass-ionomer cement to bovine dentin.

PURPOSE: To determine the adhesion of resin-modified glass-ionomer cement to bovine dentin under contaminated and decontaminated conditions. MATERIALS AND METHODS: Forty-five bovine mandibular incisors were used. The surfaces of bovine dentin specimens were subjected to Temp-bond, dental handpiece lubricant (contamination), Hibiscrub, chlorhexidine or pumice (decontamination), as well as contamination followed by decontamination. From these, 14 test groups were created to investigate the effects of these variables on the microtensile bond strength of a resin-modified glassionomer cement to dentin. In addition, scanning electron microscopy was performed to examine the effects of contamination and decontamination procedures on the dentin surfaces. The data were analyzed by one-way ANOVA, Kruskal-Wallis, and Mann-Whitney tests. RESULTS: SEM examination showed visible differences between the control group and dentin contaminated with Temp-bond or handpiece lubricant. All the contamination and decontamination test agents when used alone - except Hibiscrub - showed significant reductions in bond strength when compared to the control (p < 0.001). All the test groups subjected to contamination followed by decontamination showed a significantly reduced bond strength (p < 0.001) when compared to the control, with the exception of the handpiece lubricant/Hibiscrub combination. CONCLUSION: Under the conditions tested, Temp-bond, handpiece lubricant, chlorhexidine, and pumice may have an adverse effect on the bonding of resin-modified glass ionomer to dentin. Hibiscrub was effective in decontaminating handpiece lubricant but not Temp-bond.

[Restore two posterior teeth with modified resin-bonded-bridge].

OBJECTIVE: To restore two posterior teeth with resin-bond-bridge with attachments. METHODS: Twenty patients were selected with two adjacent posterior teeth missing and the opposite teeth were natural teeth. The mean age was 45.6 years old, 9 male and 11 female. The maxillary cases were 12 and mandibules case were 8. The female part of attachment was attached with the retainer on the bicuspid teeth; the male part was attached with the pontic. After try-in, the two parts were adhered to the abutments separately and joined by the attachment. RESULTS: The mean survival time of the 20 cases was 28.8 months, and the max was 42 months. In only one case the posterior part debonded, and it resumed being used after rebonding. CONCLUSION: In recent years the successful rate of resin-bond-bridge has got close to that of the traditional bridge. Most RBB were used to restore the single missing tooth. Now RBB with non-rigid connector can restore two missing teeth. When the teeth get stress, the directions of stress are different. The longer span of RBB with rigid connector, the bigger interbutment stress on the adhere layer. With the non-rigid connector the stress between the retainer and the adhesive layer can be reduced. Our clinic treatment showed that this kind of method got good results and even the service time was not very long.

The adverse effects of tungsten carbide grinding on the strength of dental zirconia.

OBJECTIVES: This study investigated the effects of tungsten-carbide grinding on the surface characteristics and mechanical strength of dental 3 mol% yttria-stabilized zirconia (3Y-TZP). METHODS: Two types of tungsten-carbide burs (TC), 6-blade (TC1) and 8-blade (TC2) were used to grind 3Y-TZP, in a dental air-turbine handpiece with water-cooling and were also subjected to air-particle abrasion (APA): TC1 + APA and TC2 + APA; and rubber polishing (RP): TC1 + RP and TC2 + RP; one group received only rubber-polishing RP. The control group received no treatment. Surface characterization was examined by surface roughness (Ra) and atomic force microscopy. Specimens were also observed with scanning electron microscopy (SEM) and X-ray-diffraction (XRD) for microstructure and crystalline phases. A piston-on-three-balls biaxial-flexural strength (BFS) test was performed with 15 samples-per-group and the broken specimen were observed under SEM to investigate the fracture origin pattern. One-way ANOVA, Kruskal-Wallis test and Weibull analysis were performed at α = 0.05. RESULTS: Groups TC1 and TC2 had the lowest mean BFS (p < 0.05) with up to 74 % reduction in strength. APA and RP both significantly increased the mean BFS after tungsten-carbide grinding but was still less than the control (p < 0.05). Compared to the control, the mean BFS was significantly reduced for all groups except for the RP group (p < 0.05). APA and rubber-polishing following TC2 grinding had significant higher mean BFS than those following TC1 grinding respectively (p < 0.05). SEM revealed distinct micro-cracks after tungsten-carbide grinding. SIGNIFICANCE: Tungsten-carbide burs (6- and 8-blade) are not recommended for zirconia grinding due to the significant reduction of biaxial-flexural strength and observed micro-structural surface and subsurface damage.

A comparison of visual identification of dental radiographic and nonradiographic images using eye tracking technology.

OBJECTIVES: Eye tracking has been used in medical radiology to understand observers' gaze patterns during radiological diagnosis. This study examines the visual identification ability of junior hospital dental officers (JHDOs) and dental surgery assistants (DSAs) in radiographic and nonradiographic images using eye tracking technology and examines if there is a correlation. MATERIAL AND METHODS: Nine JHDOs and nine DSAs examined six radiographic images and 16 nonradiographic images using eye tracking. The areas of interest (AOIs) of the radiographic images were rated as easy, medium, and hard, and the nonradiographic images were categorized as pattern recognition, face recognition, and image comparison. The participants were required to identify and locate the AOIs. Data analysis of the two domains, entire slide and AOI, was conducted by evaluating the eye tracking metrics (ETM) and the performance outcomes. ETM consisted of six parameters, and performance outcomes consisted of four parameters. RESULTS: No significant differences were observed for ETMs for JHDOs and DSAs for both radiographic and nonradiographic images. The JHDOs showed significantly higher percentage in identifying AOIs than DSAs for all the radiographic images (72.7% vs. 36.4%, p = .004) and for the easy categorization of radiographic AOIs (85.7% vs. 42.9%, p = .012). JHDOs with higher correct identification percentage in face recognition had a shorter dwell time in AOIs. CONCLUSIONS: Although no significant relation was observed between radiographic and nonradiographic images, there were some evidence that visual recognition skills may impact certain attributes of the visual search pattern in radiographic images.

A randomised controlled trial of two-unit cantilevered or three-unit fixed-movable resin-bonded fixed partial dentures replacing missing molars.

OBJECTIVE: To examine the short-term clinical performance and patient-reported outcomes of two-unit cantilevered (CL2) and three-unit fixed-movable (FM3) RBFPDs for replacement of single molar-sized spans. MATERIALS AND METHODS: Subjects with an 8-10 mm molar-sized edentulous span(s) and 12 pairs of occluding units were randomly assigned to receive either CL2 or FM3 RBFPD (ratio 1:1). The survival (retention of original prosthesis) and success (survival, complication-free) of RBFPDs at one-year were analysed. Patient-reported outcomes were assessed by prosthesis satisfactory questionnaire and Oral Health Impact Profile (OHIP-49). Data in mean, proportion and longevity were analysed by t-test/Mann-Whitney U test/Wilcoxon signed-rank test, chi-square and log-rank tests respectively at significance level α = 0.05. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT02239718. RESULTS: Ninety-eight RBFPDs (42 CL2 and 56 FM3) were delivered in eighty-three patients. Majority (n = 89) of the prostheses were provided by operators who have less than 2 years of clinical experience. Sixty-six patients with seventy-eight RBFPDs (35 CL2 and 43 FM3) were reviewed at one-year. One CL2 and one FM3 RBFPDs debonded, resulting in a success rate at 97.1 % and 97.7 % respectively (P > 0.05). Both RBFPDs were rebonded and the survival rate were 100 % for both designs. No significant difference in satisfactions and summary OHIP-49 scores were observed (P > 0.05). CONCLUSION: CL2 RBFPDs can be used for replacing molar-sized edentulous spans with minimal observable complications up to one-year. Longer-term data is being collected. CLINICAL SIGNIFICANCE: This clinical trial demonstrates CL2 RBFPDs have comparable clinical and patient-reported outcomes as the FM3 design. This challenges the current dogma in prosthodontics and expands the clinical use of CL2 design which is more conservative, simpler and easier for patients to maintain.

Impact of hypo-salivation on severe tooth wear: A ten-year cohort of patients received radiotherapy for nasopharyngeal carcinoma.

OBJECTIVES: This study was conducted to examine the tooth wear status of nasopharyngeal-carcinoma (NPC) patients who had received radiotherapy at least 5-year previously, and to investigate the salivary parameters that may be associated with the tooth wear. METHODS: Tooth wear status of NPC survivors were clinically assessed using the Exact Tooth Wear Index. A tooth was graded to have severe wear when more than one-third of its buccal/occlusal/lingual surface had dentine loss. At the subject-level, percentages of anterior/posterior/all teeth with severe wear were calculated. Age, number of teeth, flow-rate/buffering capacity/pH of stimulated whole (SWS) and parotid (SPS) saliva's were collected. Correlation and multiple-linear regression tests were performed at the significance level α = 0.05. RESULT: Sixty-eight participants (mean age of 60.0 ±â€¯8.9), 697 anterior and 686 posterior teeth were examined with a mean of 10-years post-radiotherapy. Severe tooth wear was found in 63 (92.6 percent) participants, 288 anterior and 83 posterior teeth. The mean percentage of anterior/posterior/all teeth with severe wear were 42.3 ±â€¯28.1, 14.5 ±â€¯19.9 and 30.0 ±â€¯21.7. Anterior teeth, particularly the incisal surface of central incisors were most affected. The mean flow-rate of SWS and SPS were 0.1 ±â€¯0.1 ml/min and 0.03 ±â€¯0.07 ml/min respectively. Thirty (44.1 percent) and 48 (70.6 percent) participants were found to have low/no buffering capacity of SWS and SPS respectively. Multiple-regression analyses revealed the SWS flow-rate was associated with the percentage of anterior teeth with severe wear (p=0.03). CONCLUSION: Anterior tooth wear is a significant dental problem among NPC survivors and was associated with hypo-salivation. CLINICAL SIGNIFICANCE: Patients with hypo-salivation should be being monitored for tooth wear particularly on the anterior teeth.

An systematic review of e-learning outcomes in undergraduate dental radiology curricula-levels of learning and implications for researchers and curriculum planners.

OBJECTIVES: To examine the outcomes of e-learning or blended learning interventions in undergraduate dental radiology curricula and analyze the nature of the knowledge levels addressed in learning interventions. METHODS: A systematic literature review was performed using a search strategy based on MeSH key words specific to the focus question and indexed in the MEDLINE database. The search again was supplemented by hand-searching of selected journals. Data were extracted relating to outcomes of knowledge and student perceptions. Analysis of the e-learning intervention was performed using a new framework to examine the level of knowledge undertaken: (1) remember/understand (2) analysis or evaluation or diagnosis and (3) performance ("knows how" or "shows how"). RESULTS: From the selected 17 papers, 11 were positive about student reported outcomes of the interventions, and 8 reported evidence that e-learning interventions enhanced learning. Out of the included studies, 8 used e-learning at the level of remember/understand, 4 at the level of analysis/evaluate/diagnosis, and 5 at the level of performance ("knows how," "shows how"). CONCLUSIONS: The learning objectives, e-learning intervention, outcome measures and reporting methods were diverse and not well reported. This makes comparison between studies and an understanding of how interventions contributed to learning impractical. Future studies need to define "knowledge" levels and performance tasks undertaken in the planning and execution of e-learning interventions and their assessment methods. Such a framework and approach will focus our understanding in what ways e-learning is effective and how it contributes to better evidence-based e-learning experiences.