Dental students' perception of their approaches to learning in a PBL programme.

AIM: To compare dental students' perceptions of their learning approaches between different years of a problem-based learning (PBL) programme. The hypothesis was that in a comparison between senior and junior students, the senior students would perceive themselves as having a higher level of deep learning approach and a lower level of surface learning approach than junior students would. This hypothesis was based on the fact that senior students have longer experience of a student-centred educational context, which is supposed to underpin student learning. PARTICIPANTS AND METHODS: Students of three cohorts (first year, third year and fifth year) of a PBL-based dental programme were asked to respond to a questionnaire (R-SPQ-2F) developed to analyse students' learning approaches, that is deep approach and surface approach, using four subscales including deep strategy, surface strategy, deep motive and surface motive. The results of the three cohorts were compared using a one-way analysis of variance (ANOVA). A P-value was set at <0.05 for statistical significance. RESULTS: The fifth-year students demonstrated a lower surface approach than the first-year students (P = 0.020). There was a significant decrease in surface strategy from the first to the fifth year (P = 0.003). No differences were found concerning deep approach or its subscales (deep strategy and deep motive) between the mean scores of the three cohorts. CONCLUSIONS: The results did not show the expected increased depth in learning approaches over the programme years.

A predictive model for alternative admission to dental education.

AIM: To compare academic progress and performance of students admitted through two admission systems and to analyse the predictive power of different components in an alternative admission. SAMPLE AND METHODS: The subjects were students admitted to the dental programme at Malmö University, Sweden. The grade admission group was admitted on grades from secondary school (n = 126) and the alternative admission group via an alternative admission procedure (n = 157). The alternative admission procedure consisted of the following components: problem-solving matrices, spatial capacity tested with folding and tin models, manual dexterity, capacity for empathy and interview. Comparisons were made for academic progress (dropouts from the programme and study rate) and academic performance (examinations failed and outcomes of a comprehensive clinical examination). Spearman correlation was calculated for each component of the alternative admission procedure and academic progress as well as academic performance. Multivariate analyses were also carried out. RESULTS: Compared to the grade admission group, the alternative admission group presented lower rate of dropouts (3% vs. 20%, P < 0.001) and a larger proportion graduated within the expected time (88% vs. 60%, P < 0.01). There was no difference between the groups concerning academic performance. Capacity of empathy was correlated with study rate and outcomes of the clinical examination. The matrices predicted low proportion failed examinations and high students' self-assessments in the clinical examination. Predictive power of folding was limited and so was that of the interview. Manual dexterity was not correlated with academic progress or performance. CONCLUSIONS: Results support further development of admission selection criteria, particularly emphatic capacity that predicts important student academic achievements.

Dentists reflect on their problem-based education and professional satisfaction.

AIM: To determine the way in which Malmö University dental graduates perceive their problem-based dental education and evaluate their professional satisfaction. METHOD: The first five cohorts (graduating in years 1995-1999) of the problem-based curriculum were invited to participate. Of 166 graduates, 77% responded to a questionnaire comprising 20 questions on aspects of their dental education, professional situations and interest in postgraduate education. They were asked to rank their perception of their dental education and satisfaction with their professional situation on a visual analogue scale (VAS) with endpoints ranging from 'Not at all' (1) to 'Very well' (10). For other statements, the markings were made on a Likert scale from 1 (not important/not satisfied) to 5 (very important/very satisfied). There were also open-ended questions. RESULTS: Most respondents perceived their education to prepare them well for a career in dentistry (median score VAS 8), and 90% rated above six on a VAS for their professional satisfaction as dentists. Importance and satisfaction were highly correlated with principles of the curriculum: holistic view, oral health, lifelong learning, integration between theory and clinic, and clinical competence. Forty-five per cent of the graduates noted the problem-based learning approach as the most valuable asset of their education, and 19% cited training in oral surgery as a deficit. Of the respondents, 77% expressed interest in specialist training and 55% in research education. CONCLUSION: Problem-based education was perceived to prepare graduates well for their profession, and their professional satisfaction was high.

Third molar treatment outcome: a comparison of patients' preferences in Sweden and Wales.

AIM: To elucidate and compare patients' outcome preferences for removal and retention of mandibular third molars in Sweden and Wales. SUBJECTS AND METHOD: The subjects comprised patients referred and scheduled for removal of one or both mandibular third molars in Sweden and Wales. The multi-attribute utility (MAU) methodology was applied to study patients' preferences for outcomes of removal and retention of the mandibular third molar. RESULTS: Relative weighting of domains was similar in the two countries. "Home and social life" received the highest relative weighting in Sweden and "general health and wellbeing" in Wales. "Your appearance" received the lowest relative weighting in both countries. In both Sweden and Wales operative jaw fracture was considered to be the outcome with most impact, and dentigerous cyst and imbricated incisors the least impact. Outcome ranking was similar in both countries and operative outcomes were considered by patients to be more detrimental to health than retention outcomes. CONCLUSIONS: This comparison showed that patients' preferences in Sweden and Wales were similar and that the outcomes of surgery were considered worse after third molar removal than retention. Patient-orientated treatment decisions were less subject to variation than clinician-orientated decisions.

Effective dose of cone beam CT (CBCT) of the facial skeleton: a systematic review.

OBJECTIVE: To estimate effective dose of cone beam CT (CBCT) of the facial skeleton with focus on measurement methods and scanning protocols. METHODS: A systematic review, which adhered to the preferred reporting items for systematic reviews (PRISMA) Statement, of the literature up to April 2014 was conducted. Data sources included MEDLINE®, The Cochrane Library and Web of Science. A model was developed to underpin data extraction from 38 included studies. RESULTS: Technical specifications of the CBCT units were insufficiently described. Heterogeneity in measurement methods and scanning protocols between studies made comparisons of effective doses of different CBCT units and scanning protocols difficult. Few studies related doses to image quality. Reported effective dose varied across studies, ranging between 9.7 and 197.0 µSv for field of views (FOVs) with height ≤5 cm, between 3.9 and 674.0 µSv for FOVs of heights 5.1-10.0 cm and between 8.8 and 1073.0 µSv for FOVs >10 cm. There was an inconsistency regarding reported effective dose of studies of the same CBCT unit with the same FOV dimensions. CONCLUSION: The review reveals a need for studies on radiation dosages related to image quality. Reporting quality of future studies has to be improved to facilitate comparison of effective doses obtained from examinations with different CBCT units and scanning protocols. A model with minimum data set on important parameters based on this observation is proposed. ADVANCES IN KNOWLEDGE: Data important when estimating effective dose were insufficiently reported in most studies. A model with minimum data based on this observation is proposed. Few studies related effective dose to image quality.

Demonstration of 99mTc-labelled plasmin on the surface of ex vivo thrombi.

In an vitro system using the Chandler model for the preparation of in vitro thrombi trace amounts of porcine or human 99mTc-labelled plasmin was found to adsorb to the surface of a preformed thrombus. A radioactive lining of the thrombus could be demonstrated using autoradiography after addition of 99mTc-labelled plasmin in concentrations of 0.04 - 0.07 or 0.4 - 0.7 CTA u/thrombus made from 2 ml whole blood (0.035 - 0.35 microM). The same pattern was found for porcine as for human plasmin. The presence of tranexamic acid in concentrations of 3 to 12 mM did not affect the binding of plasmin indicating that the plasmin binding to fibrin was independent of the lysine binding sites. Furthermore alpha 2-antiplasmin was demonstrated on/in the thrombus also when no plasmin was present indicating a binding of alpha 2-antiplasmin to the thrombus. The plasmin bound to the thrombus was proteolytically inactive. In order to obtain thrombolysis most of the alpha 2-antiplasmin in the surrounding medium had to be neutralized.

Dentists' judgment strategies on prophylactic removal of mandibular third molars.

The number of molars selected for prophylactic removal varies widely among general dental practitioners and oral surgeons. To understand the basis for such variations, we investigated two hypotheses: (1) Individual judgment strategies will differ concerning the use of cues (items of information), and (2) few dentists will integrate the cues according to evidence in the literature. To analyze 30 general dental practitioners' (GDPs) and 10 oral surgeons' use of cues in the judgment preceding the treatment decision, we used the Brunwik's lens as a conceptual model. The cues were the patient's age, and the angular position and the degree of impaction of the molar. The clinical situation was simulated by written case descriptions. The proportion of variation explained by the cues and their combinations (total model) varied between 61% and 100% and between 4% and 76% as main effects. Two GDPs and one oral surgeon integrated the cues additively, i.e., any of the cues is independent of the other cues in the judgment. In general, the dentists integrated the cues interactively, i.e., the impact of one cue depends on the levels of some other cues. Even though most variations in judgments were accounted for by the cues, the dentists did not integrate the cues according to evidence in the literature and lacked insight into their decision-making thought processes.

Radiation dosimetry in radiology of the temporomandibular joint.

The absorbed doses and energy imparted during conventional radiography and tomography of the temporomandibular joint were examined. Absorbed doses from the lateral-oblique transcranial projection and lateral tomography were low (0.02 to 7 mGy). From the axial projection the thyroid gland and salivary glands received a substantial dose (15 to 54 mGy) which was considerably decreased using an improved design of collimator. Radiation to the lens of the eye for the transmaxillary projection and for frontal tomography was 3 to 8 mGy. This can be reduced by a factor of 25 using lead-glass eye shields. The mean energy imparted from a bilateral examination of the temporomandibular joints using axial projection, four exposures for the transcranial lateral-oblique views, two exposures in the transmaxillary projection and lateral tomography views using a multi-film cassette was 34 mJ. The axial projection accounted for 50% of this figure.

Dentists' decisions on prophylactic removal of mandibular third molars: a 10-year follow-up study.

OBJECTIVES: In recent years, several critical outcome studies concerning the prophylactic removal of mandibular third molars have been published. These would appear to motivate a more restrictive approach today as compared with 10 years ago. The aim of the present study was to examine dentists' decisions on the prophylactic removal of impacted mandibular third molars over a 10-year period. METHODS: Thirty-six cases were selected so as to represent an equal distribution of males and females, ages, angular position and degree of impaction of the molar. Twenty-six general dental practitioners (GDPs) and 10 oral surgeons judged the same cases on two occasions 10 years apart. RESULTS: Calculated for each category of dentists, there was no significant difference in the mean number of molars designated for removal between the two occasions. Two GDPs and three oral surgeons presented a higher removal rate, whereas five GDPs presented a lower removal rate on the second occasion as compared to the first one. The dentists presented a considerable interindividual variation in removal rate, between 0 and 22 molars on the first occasion and between 0 and 25 molars on the second occasion. CONCLUSION: In the decisions on prophylactic removal of mandibular third molars, there has been no change over the last 10 years towards a more noninterventionist attitude. Thus, the dentists seem not to have been influenced by the evidence that this intervention is not cost-effective.

General dental practitioners' evaluation of the need for extraction of asymptomatic mandibular third molars.

Thirty general dental practitioners were asked to evaluate the need for extraction of asymptomatic mandibular third molars. Thirty-six mandibular third molars with equal distribution of angular positions, impaction status, males and females and age groups were selected. To estimate the consistency of the evaluation, the 36 cases were duplicated so that, in all, 72 teeth were evaluated. The number of molars proposed to be extracted by the observers varied from 0 to 26. There was no third molar which all observers agreed should be extracted. The two molars which most observers, 25 and 23 of altogether 30 observers, proposed to be extracted were partially covered by soft tissue. The decision not to extract two molars was unanimous. Both of these were completely covered by bone tissue and positioned vertically. The mean overall intra-observer agreement for the therapeutical decision was 92%, with a range of 69-100%. The length of professional experience of the observer did not influence the evaluation whether or not to extract. We conclude that there is a great variation among general dental practitioners regarding their evaluation on the need for removal of asymptomatic mandibular third molars.

Decision analysis in dentistry--the last 30 years.

OBJECTIVES: To review publications in dentistry of decision analyses during the last 30 years. METHODS: A systematic review of the English literature from 1969 to 1998 was performed using specified indexing terms. The number of retrieved articles in dentistry was compared with the number of articles in medicine. The quality of articles in dentistry presenting a decision tree with utilities and a sensitivity analysis was judged using a published peer review process. We report weaknesses of the analyses together with selected applications. RESULTS: Sixty-seven articles were published on decision analysis in dentistry. Whilst the number of articles published in medicine has accelerated there has been a decline in the last four years in dental publications. Only 22 of the articles in dentistry presented a decision analysis with utilities and a sensitivity analysis. CONCLUSIONS: Current weaknesses of the decision analyses reported were: opaque basic assumptions in the description of the analysis, lack of data on patient preferences and of reliable data on the chances of the long-term effects and side effects of intervention together with an absence of sensitivity analyses. The decision analysis approach complements that of "evidence-based health care" by enabling the best empirical evidence to be used in clinical practice. Formal methods such as decision analysis will promote the rational use of existing knowledge. For it to do this the quality of research data will have to improve in dentistry. Furthermore decision analysis is important in education to demonstrate explicitly how decisions might be arrived at and improved.

Comparison between panoramic and posterior bitewing radiography in the diagnosis of periodontal bone loss.

A study is reported comparing the diagnostic yield of panoramic and posterior bitewing radiographs when used to image periodontal bone disease. It is concluded that there is a high concordance between the findings from the two types of radiographs but that the concordance varies with the degree of bone loss and tooth type. Consequently when panoramic radiography is used in clinical practice, the examination should be supplemented by intraoral radiographs in regions when image quality is poor in the panoramic image and where there are structures of special interest.

A study of indications used for removal of the mandibular third molar.

To study the indications used for removal of the mandibular third molar, questionnaires were sent to 35 Oral Surgery Clinics in Sweden, out of which 29 clinics participated. In each clinic, the questionnaires were to be recorded for 30 patients. The indications for removal were classified into 15 groups. There were also questions about symptoms as well as eruption status for the molar being removed. The results were based on data from 870 individuals with a mean age of 27 years. More than half of the removed third molars (54%) presented no subjective symptoms. Such symptoms were more frequent in association with fully or partially erupted molars than molars completely covered by soft or bone tissue. The indication for removal was classified as prophylactic in 27% and as orthodontic in 14%. Earlier episodes of pericoronitis consisted of 1/4 of the indications and caries or pulpitis of the third molar made up 13%. Pathologic entities like cysts, tumours and root resorption were registered in less than 3% each, and were more frequent among patients 40 years of age or older.

Macroscopic and microscopic appearance of radiologic findings in temporomandibular joints from elderly individuals. An autopsy study.

The macroscopic and microscopic appearance of radiologic findings in 40 temporomandibular joints (TMJ) taken at autopsy from 20 elderly individuals was investigated. The radiologic signs of erosion and sclerosis were strongly associated with macroscopic articular surface destruction only on the condyle while the soft tissue lining was most often intact in areas with a sclerosis of the temporal component. Radiologic concavity, osteophyte, and flattening presented none or mild macroscopic changes. The microscopic appearance of erosion and cyst formation was characterized by the presence of a cell-rich fibrous and well-vascularized connective tissue. In 4 joints with fibrous ankylosis, an articular soft tissue lining was completely lacking. In areas with radiologic sclerosis, thickening of the cortical and subcortical bone was observed. Both erosions and sclerosis were found in most joints with anterior disc position or disc perforation. It was concluded that radiologic signs of erosion and sclerosis in the condyle are more reliable signs of joint disease than such changes in the temporal component.

Clinical and radiological findings in temporomandibular joints with disc perforation.

Sixteen temporomandibular joints from 15 patients, reported to have disc perforation at arthrography, were studied. Pain from the TMJ region was reported by 11 patients. Clicking was found in 6 joints and crepitation in 6 joints. Nine patients displayed a deviation of the mandible at maximum mouth opening towards the affected side. The muscles of the affected side were tender on palpation more frequently than those on the contralateral side. The disc perforation was located in the posterior attachment in most joints. An anterior disc displacement was found in all joints except one, which exhibited a normal disc position. In 4 joints with an anterior disc displacement with reduction, the configuration of the discs varied, whereas in all 11 joints with an anterior disc displacement without reduction the disc was biconvex. In most joints, the condyle was located in a central position in the fossa in the intercuspal position and 13 joints were tomographically diagnosed as being osteoarthrotic. It is concluded that most joints with disc perforations are osteoarthrotic and the most severe clinical and radiological findings are associated with an anterior disc displacement without reduction.

Computed tomography versus single-contrast arthrotomography in evaluation of the temporomandibular joint disc. A study of autopsy specimens.

The lateral, central and medial parts of 15 right temporomandibular joint autopsy specimens were studied to compare the ability of computed tomography (CT) and single-contrast arthrotomography in diagnosing the disc position and configuration. The radiologic findings were compared with macroscopic findings in a blinded fashion. In the CT examination, the diagnostic accuracy was 40% in determining the disc position and 26.7% in determining the disc configuration. However, in many areas of the joints the disc was not possible to evaluate by CT. With arthrotomography the diagnostic accuracy in determining the disc position was 75.6% and the disc configuration 60%. The sensitivity of CT was 0.45 and of arthrotomography 0.95 for the diagnosis of the disc position. The specificity was 0.87 for CT and 0.76 for arthrotomography. From these results, we conclude that arthrotomography is a reliable aid to diagnosis of TMJ disc changes and that CT cannot replace it.

Assessment of the trabecular pattern before endosseous implant treatment: diagnostic outcome of periapical radiography in the mandible.

OBJECTIVES: To study the diagnostic outcome of periapical radiography in the assessment of the bone trabecular pattern of the mandible. STUDY DESIGN: Mandibular autopsy specimens were radiographed. Seven observers assessed the radiographs with the aid of a proposed classification with and without reference images and the classification presented by Lekholm and Zarb. Accuracy was estimated on the basis of morphometric measurements of trabecular bone volume. Observer agreement was calculated as the estimated probability of agreement between and within observers and as kappa index. RESULTS: With the classification proposed by us, the overall accuracy was 58% with and 50% without reference images. The accuracy for assessing dense trabeculation was higher (78%) than that for sparse trabeculation (28%). The accuracy of the proposed classification by Lekholm and Zarb was not possible to evaluate. The interobserver agreement varied between 49% and 64% and the intraobserver agreement between 75% and 86%. CONCLUSION: A new classification with reference images is recommended to assess the trabecular pattern in periapical radiographs before implant treatment.

Diagnostic accuracy of direct digital dental radiography for the detection of periapical bone lesions: overall comparison between conventional and direct digital radiography.

OBJECTIVES: The diagnostic accuracy of direct digital radiography for the detection of small, experimentally made, periapical lesions was compared with that of E speed film. The high- and low-contrast resolutions of the imaging systems were also compared. STUDY DESIGN: The high-contrast resolution was evaluated with a line pair plate. The low-contrast resolution was determined with a contrast-detail plexiglass phantom. To evaluate the diagnostic accuracy, the periapical region of dry human mandibles was examined. Receiver operating characteristic based on the readings of seven observers were generated. RESULTS: The high-contrast resolution of the digital system was inferior, but the low-contrast resolution was comparable to that of E-speed film. For diagnostic accuracy no significant difference was seen between the areas under the receiver operating characteristic curves. CONCLUSIONS: The quality of the direct digital images is comparable to that of E-speed film for the detection of periapical bone lesions.

Global trends in oral and maxillofacial radiology education.

Although the content of the undergraduate dental curriculum has evolved alongside the changes in dental practice, the methods and structure of the course have remained remarkably constant. In this article the recent developments in higher education are reviewed in depth and some changes in the pattern and setting of oral health outlined. Global trends in education in oral and maxillofacial radiology, with particular reference to undergraduate, postgraduate, and continuing professional education, are described against this background.