The assessment of impacted maxillary canine position with panoramic radiography and cone beam CT.

OBJECTIVE: The aim of this study was to correlate the position of impacted maxillary canines on panoramic radiography with cone beam CT (CBCT) and analyse the labiopalatal position of canines and root resorption of permanent incisors in CBCT according to the mesiodistal position of canines on panoramic radiographs. METHODS: This study was a retrospective radiographic review of 63 patients with 73 impacted maxillary canines. The mesiodistal position of the canine cusp tip was classified by sector location and analysed on 73 impacted canines from 63 panoramic radiographs. The labiopalatal position of the impacted canines and root resorption of permanent incisors were evaluated with CBCT. The sector location on panoramic radiographs was compared with the labiopalatal position of impacted maxillary canines on CBCT. The statistical correlation between panoramic and CBCT findings was examined using the χ(2) test and the Fisher's exact test. RESULTS: Labially impacted canines in CBCT were more frequent in Panoramic Sectors 1, 2 and 3, mid-alveolus impacted canines were more frequent in Sector 4 and palatally impacted canines were more frequent in Sector 5. There was a statistically significant association between the panoramic sectors of the impacted canines and the labiopalatal position of the canines (p < 0.001). Root resorption of permanent incisors showed a significant difference according to sector location (p < 0.001) and was observed in Sectors 3, 4 and 5. CONCLUSIONS: This study suggests that the labiopalatal position of impacted canines and resorption of permanent incisors might be predicted using sector location on panoramic radiography.

Is protective equipment useful in preventing concussion? A systematic review of the literature.

OBJECTIVE: To determine if there is evidence that equipment use reduces sport concussion risk and/or severity. DATA SOURCES: 12 electronic databases were searched using a combination of Medical Subject Headings and text words to identify relevant articles. REVIEW METHODS: Specific inclusion and exclusion criteria were used to select studies for review. Data extracted included design, study population, exposure/outcome measures and results. The quality of evidence was assessed based on epidemiologic criteria regarding internal and external validity (ie, strength of design, sample size/power calculation, selection bias, misclassification bias, control of potential confounding and effect modification). RESULTS: In total, 51 studies were selected for review. A comparison between studies was difficult due to the variability in research designs, definition of concussion, mouthguard/helmet/headgear/face shield types, measurements used to assess exposure and outcomes, and variety of sports assessed. The majority of studies were observational, with 23 analytical epidemiologic designs related to the subject area. Selection bias was a concern in the reviewed studies, as was the lack of measurement and control for potentially confounding variables. CONCLUSIONS: There is evidence that helmet use reduces head injury risk in skiing, snowboarding and bicycling, but the effect on concussion risk is inconclusive. No strong evidence exists for the use of mouthguards or face shields to reduce concussion risk. Evidence is provided to suggest that full facial protection in ice hockey may reduce concussion severity, as measured by time loss from competition.

Sport concussion assessment tool: baseline values for varsity collision sport athletes.

OBJECTIVE: To determine baseline symptom and neurocognitive norms for non-concussed and previously concussed varsity athletes using the sport concussion assessment tool (SCAT). STUDY DESIGN: Descriptive cohort study. SETTING: University of Calgary. SUBJECTS: 260 male and female university football, ice hockey and wrestling athletes over three seasons (2005-7). METHODS: A baseline SCAT was completed during preseason medical evaluation. Subjects were grouped as follows: all participants, men, women, never concussed (NC) and previously concussed (PC). MAIN RESULTS: The mean age of participants was 20.5 years (range 17-32). In total, 41.2% of all athletes had a total post-concussion symptom scale (PCSS) score of 0. The mean baseline PCSS scores were as follows: all participants 4.29; men 3.52; women 6.39; NC 3.75 and PC 5.25. The five most frequently reported symptoms for all athletes were fatigue/low energy (37% of subjects), drowsiness (23%), neck pain (20%), difficulty concentrating (18%) and difficulty remembering (18%). The median immediate recall score was 5/5 for all groups. Women scored a median of 5/5 on delayed recall, whereas all remaining groups scored a median of 4/5. Months in reverse order were successfully completed by 91.6% of subjects. All participants, women and PC scored a median of 6 on reverse digits, whereas men and NC scored a median of 5. CONCLUSIONS: The mean SCAT baseline PCSS score was approximately 5, although just under half of the athletes scored 0. Female athletes scored better on tests of neurocognitive function. PC athletes scored better than NC athletes on all neurocognitive tests except delayed five-word recall.

Computerized tomography-based imaging and surgical guidance in oral implantology.

Computerized tomography (CT)-based imaging and surgical guidance carry both radiographic information such as height, density, and width of bone and clinical information such as axis of orientation for a successful prosthodontic result, thus determining the trajectory, depth, and distribution of the implants. The objective of this report is to review the associated literature and recent developments in CT-image-based information and surgical guidance systems. This report attempts to provide an argument for the development of evidence-based research on the utility of such systems and their effect on outcome in oral implantology.

Lingual vascular canals of the interforaminal region of the mandible: evaluation with conventional tomography.

The presence of lingual vascular foramina and canals in the interforaminal region may increase the risk of surgical complications during implant placement, bone grafting procedures and osteodistraction. Oral and maxillofacial radiologists should recognize this anatomical variant and include a description in their interpretative report to inform the referring clinician of the potential for surgical complications.

Calcification of the interclinoid and petroclinoid ligaments of sella turcica: a radiographic study of the prevalence.

OBJECTIVES: The purpose of this study was to evaluate the prevalence of calcifications of the sella turcica, in particular, calcification of the interclinoid and petroclinoid ligaments (PCL). DESIGN: Radiographic analysis of preoperative cephalometric film images. SETTING AND SAMPLE POPULATION: Lateral cephlometric radiographs of 255 subjects presenting for orthodontic evaluation were reviewed. The number of subjects selected for this study was determined by power analysis. EXPERIMENTAL VARIABLE: Two calibrated raters reviewed cephalometric projections and scored the films using a standardized rating scale. OUTCOME MEASURE: The rating scale classified interclinoid ligaments (ICL) into one of four categories depending on the degree of calcification and PCLs as either, no calcification, partial or complete calcification. RESULTS: Of all subjects, calcification of the ICL ranged from 39% rated as more than half calcified to 8% completely calcified. Petroclinoid analysis revealed 67% with no calcification, 23% with partial calcification and 9% completely calcified. Spearman's correlations were computed between age and the degree of calcification and between the degree of calcification for these two ligaments with a significant association between age and degree of calcification in the PCL, r = 0.185 (p = 0.003) and a significant association between the degree of calcification in the petroclinoid and ICLs, r = 0.186 (p = 0.003). In addition, chi-squared tests demonstrated statistically significant associations between the presence of calcification in the PCL to the distribution of age (p = 0.041) and between the presence of calcification in the ICL to the distribution of age (p = 0.045). CONCLUSION: As calcification of these ligaments has suggestive associations with disease entities, their recognition as a variant of normal anatomy should be evaluated when assessing cephalometric radiographs.

The impact of face shield use on concussions in ice hockey: a multivariate analysis.

OBJECTIVE: To identify specific risk factors for concussion severity among ice hockey players wearing full face shields compared with half face shields (visors). METHODS: A prospective cohort study was conducted during one varsity hockey season (1997-1998) with 642 male ice hockey players (median age 22 years) from 22 teams participating in the Canadian Inter-University Athletics Union. Half of the teams wore full face shields, and half wore half shields (visors) for every practice and game throughout the season. Team therapists and doctors recorded on structured forms daily injury, participation, and information on face shield use for each athlete. The main outcome measure was any traumatic brain injury requiring assessment or treatment by a team therapist or doctor, categorised by time lost from subsequent participation and compared by type of face shield worn. RESULTS: Players who wore half face shields missed significantly more practices and games per concussion (2.4 times) than players who wore full face shields (4.07 sessions (95% confidence interval (CI) 3.48 to 4.74) v 1.71 sessions (95% CI 1.32 to 2.18) respectively). Significantly more playing time was lost by players wearing half shields during practices and games, and did not depend on whether the athletes were forwards or defence, rookies or veterans, or whether the concussions were new or recurrent. In addition, players who wore half face shields and no mouthguards at the time of concussion missed significantly more playing time (5.57 sessions per concussion; 95% CI 4.40 to 6.95) than players who wore half shields and mouthguards (2.76 sessions per concussion; 95% CI 2.14 to 3.55). Players who wore full face shields and mouthguards at the time of concussion lost no playing time compared with 1.80 sessions lost per concussion (95% CI 1.38 to 2.34) for players wearing full face shields and no mouthguards. CONCLUSIONS: The use of a full face shield compared with half face shield by intercollegiate ice hockey players significantly reduced the playing time lost because of concussion, suggesting that concussion severity may be reduced by the use of a full face shield.

Teleradiology.

The technology of digital imaging and image transmission is here. Notwithstanding all the advancements that have been made in teleradiology, this technology remains in its adolescence with respect to medicine--and infancy with respect to dentistry. As with any new technology, acceptance is a function of time. Individual practitioners' comfort levels with computerization, digital imaging, and long-distance communication will invariably affect the scenario. The advantages of savings in terms of cost and time, coupled with an increased demand for tertiary health care in underserved urban and rural areas, will facilitate the acceptance of teleradiology. Rapid advances of the last decades have created an electronic society only dreamed about in 1970. These changes can be expected to continue at an ever-increasing rate, and dentists must prepare themselves to be in step with these innovations.

Comparative radiopacity of tetracalcium phosphate and other root-end filling materials.

AIM: This study compared the radiopacity of tetracalcium phosphate (TTCP) and 11 root-end filling materials relative to human dentine. METHODOLOGY: Specimens of 2 mm thickness and a graduated aluminium stepwedge were placed on dental X-ray films and exposed to an X-ray beam. The optical densities of the specimens and aluminium steps were measured. The optical densities of the specimens were correlated to the equivalent thickness of aluminium with a regression analysis equation. The equation was used to calculate the equivalent aluminium thickness of each of the specimens. RESULTS: Nine of the materials were found to be of acceptable radiopacity (at least 2 mm Al more radiopaque than dentine). TCCP and two of the glass-ionomer compounds were found to have insufficient radiopacity to be radiographically distinguishable from human dentine. CONCLUSIONS: All the materials were found to be distinguishable radiographically from dentine, except for Vitrebond, TTCP and Ketac-Fil. Amalgam was the most radiopaque material and Ketac-Fil was the least radiopaque material tested.

Head and neck injuries among ice hockey players wearing full face shields vs half face shields.

CONTEXT: Speculation exists that use of a full face shield by ice hockey players may increase their risk of concussions and neck injuries, offsetting the benefits of protection from dental, facial, and ocular injuries, but, to our knowledge, no data exist regarding this possibility. OBJECTIVE: To determine the risk of sustaining a head or neck injury among intercollegiate ice hockey players wearing full face shields compared with those wearing half shields. DESIGN, SETTING, AND PARTICIPANTS: Prospective cohort study conducted during the 1997-1998 Canadian Inter-University Athletics Union hockey season of 642 male hockey players (mean age, 22 years) from 22 teams. Athletes from 11 teams wore full face shields and athletes from 11 teams wore half face shields during play. MAIN OUTCOME MEASURE: Reportable injury, defined as any event requiring assessment or treatment by a team therapist or physician or any mild traumatic brain injury or brachial plexus stretch, categorized by time lost from subsequent participation and compared by type of face shield. RESULTS: Of 319 athletes who wore full face shields, 195 (61.6%) had at least 1 injury during the study season, whereas of 323 who wore half face shields, 204 (63.2 %) were injured. The risk of sustaining a facial laceration and dental injury was 2.31 (95% confidence interval [CI], 1.53-3.48; P<.001) and 9.90 (95% CI, 1.88-52.1; P = .007) times greater, respectively, for players wearing half vs full face shields. No statistically significant risk differences were found for neck injuries, concussion, or other injuries, although time lost from participation because of concussion was significantly greater in the half shield group (P<.001), than in the group wearing full shields. CONCLUSIONS: These data provide evidence that the use of full face shields is associated with significantly reduced risk of sustaining facial and dental injuries without an increase in the risk of neck injuries, concussions, or other injuries.

Influence of the digital image display monitor on observer performance.

OBJECTIVE: To assess the influence of the display monitor on observer performance. MATERIAL AND METHODS: Artificial enamel lesions were created in 40 extracted teeth at random using 1/4 and 1/2 round burs. Teeth were mounted in dental stone blocks to simulate a hemidentition. Approximate exposures were recorded at 70 kVp using a Digota (Soredex, Orion Corp, Helsinki, Finland) digital imaging system, calibrated to achieve optimum density. Six dentists rated each image on a five-point scale for the presence or absence of a lesion. Radiographic images were viewed on the following monitors: (1) AlphaScan 711 (Sampo Corp.); (2) Multiscan 17 Se II (Sony Electronics Inc.); (3) DS 2000 (Clinton Electronics Corp.) and (4) Latitude CP Laptop (Dell Computer Corp.). Raters were allowed to magnify and to adjust density and contrast of each image at will. Receiver Operating Characteristic (ROC) analysis was performed and curves were plotted for each image. Data was subjected to repeated measures analysis of variance and ordinal logistic regression to test for significance between variables and to determine odds ratios. RESULTS: Mean ROC curve areas ranged from 0.8728 for the Sampo monitor to 0.8395 for the Sony. Repeated measures analysis of variance showed significant differences between observers (P < 0.0001), lesion size (P < 0.0001), examiner/monitor interaction (P < 0.033) and examiner/block interaction (P < 0.013). However, no significant difference was found between monitors. CONCLUSION: This study suggests that observer performance is independent of the visual characteristics of the display monitor.

A reliability comparison of submentovertex and zonographic methods of horizontal condylar angle estimation.

OBJECTIVE: The objectives of this retrospective clinical study were, first, to compare submentovertex radiography and zonographic temporomandibular joint orientation programs that use the Scanora imaging system with respect to the reproducibility with which the angulation of the horizontal condylar axis may be determined and, second, to assess the level of agreement between the 2 methods. STUDY DESIGN: Submentovertex radiographs and zonographic projections of 16 joints (8 patients) were evaluated. Two raters independently determined the horizontal angulation of each condyle 3 times using each method. Horizontal condylar angle measurements differing by no more than 5 degrees were considered to be in agreement. Statistical analyses were performed with a repeated-measures analysis of variance, sign tests, and Wilcoxon signed rank test. RESULTS: No significant difference was found in the 3 measurements between the 2 raters (P = .9122) or between the raters adjusted for method (P = .5093). A significant difference was found between methods (P = .0001). Intrarater agreement values were 81% and 88% for the submentovertex method and 75% for each rater for the zonographic method. Interrater agreement was 94% for each method. Intermethod agreement was 50% for one rater and 81% for the other. CONCLUSIONS: The submentovertex and zonographic methods of determining the horizontal condylar angulation demonstrated consistency and reliability both within and between the raters. However, the zonographic method did not agree with the submentovertex method. This findings does not imply that the zonographic is not a clinically acceptable technique for the determination of the horizontal condylar angulation when subsequent tomographic projections are made on the same unit with the same head-positioning device.

Endodontic working length assessment. Comparison of storage phosphor digital imaging and radiographic film.

OBJECTIVE: This study compared the difference in interpretation of the position of endodontic file tips between two imaging systems: photostimulable storage phosphor luminescence imaging versus radiographic film. STUDY DESIGN: Thirteen patients were selected at random. Preoperative and trial file length radiographs were made with a dual image receptor composed of a Digora Digital Imaging Plate and a piece of Ektaspeed Plus film. Exposure techniques for E-speed film were used. Root length and file length measurements were made from digital images with the Digora system's measuring tools. Measurements were also made on radiographic film with a 7 x measuring magnifier. Root length, file length, and their difference were compared for both film and digital images. RESULTS: Differences were found to be less in digital than in film images. Photostimulable storage phosphor luminescence imaging performed similarly to Ektaspeed Plus film for measuring root lengths, but file tip positions (especially of small file sizes) were difficult to visualize with E-speed film. CONCLUSIONS: The smaller difference between file tip and root apex found with digital imaging suggests that this technique is more accurate to assess trial file length. This imaging modality for assessing file positions during root canal treatment may be beneficial to the practitioner.

Effect of different background lighting conditions on diagnostic performance of digital and film images.

OBJECTIVE: To compare the performance of a photostimulable phosphor (PSP) imaging system with radiographic film for the detection of approximal lesions under two background lighting conditions. METHODS: Bitewing exposures were made of the extracted human teeth with artificial approximal lesions using D-speed and E-speed radiographic film and a PSP imaging plate. Eight dentists rated 12 approximal surfaces in each image on a 5-point scale. Images were viewed with overhead fluorescent room lighting on and off. ROC curves were generated for each image receptor and lighting condition. Repeated measures analysis of variance ANOVA tested differences between observers, lesion size, image receptor, lighting condition. RESULTS: Mean ROC curve areas for D-speed film viewed in full ambient light scored highest (0.8030) followed by E-speed film using dark conditions (0.7386). The lowest mean curve area was found when PSP (enhanced mode) images were viewed in a dark room (0.6726). Significant differences were found between observers, lesion size, image receptor and image receptor-lesion size interaction. No significant difference was found with background lighting. CONCLUSIONS: Background lighting does not appear to effect the ability to detect artificial approximal lesions.

Comparison of titanium and cobalt-chromium removable partial denture clasps.

STATEMENT OF PROBLEM: The use of titanium alloys for removable partial dentures is an increasingly popular application. While the flexibility of titanium would allow for cast clasps to be placed in deeper undercuts than advisable with cobalt-chromium, it is possible that the retentive forces of the titanium clasp might not maintain sufficient retention after repeated flexing of the clasp arm during insertion and removal of the partial denture. PURPOSE: This study assessed the characteristics of cast clasps made of titanium and titanium alloys to determine whether these materials are suitable alternatives for removable partial denture applications. MATERIAL AND METHODS: Removable partial denture clasps at two undercut depths were fabricated from commercially pure titanium, titanium alloy (Ti-6A1-4V), and cobalt-chromium. Loss of retention force was measured as the clasps underwent 3 years of simulated clinical use. The data were subjected to ANOVA and Scheffé's tests to determine differences. Evidence of casting defects and porosity was evaluated by radiographic examination and nonparametric statistics. SEM microscopy was used to observe surface characteristics that were described qualitatively. RESULTS: For the 0.75 mm undercut specimens, there was less loss of retention for clasps made from pure titanium and titanium alloy than for cobalt-chromium clasps. Porosity was more apparent in the pure titanium and titanium alloy clasps than in those made from cobalt-chromium, but the amount of porosity did not correspond to evidence of fractures or permanent deformation. CONCLUSIONS: The long-term retentive resiliency of the pure titanium and titanium alloy clasps suggests that these materials are suitable for removable partial dentures.

Effect of the geometry of the intraoral position-indicating device on effective dose.

OBJECTIVE: The objective of this study was to calculate and compare the effective dose and to estimate risk from the use of intraoral position-indicating devices of differing geometries. STUDY DESIGN: Thermoluminescent dosimeters were placed at selected sites in the upper portion of a tissue-equivalent human phantom to record the equivalent dose to weighted tissues and organs. The phantom was exposed to simulated complete mouth surveys with either a long (29.8 cm) or short (19.6 cm) round open-end position-indicating device, a long (35.3 cm) or short (23.3 cm) rectangular open-end position-indicating device, or a pointed (29.6 cm) closed-end position-indicating device. RESULTS: The effective dose was calculated as the sum of the equivalent doses to each organ or tissue multiplied by that organ or tissue's weighting factor. The salivary glands were included as part of the remainder. The effective dose ranged from 362 micro Sv for the pointed position-indicating device, to 63 micro Sv for both the long and the short rectangular position-indicating devices. CONCLUSIONS: These effective doses were calculated to represent a probability for stochastic effects that range in magnitude from 26 x 10(-6) to 4.6 x 10(-6).

Effective dose and risk assessment from detailed narrow beam radiography.

Studies of the effectiveness of commonly used imaging techniques have shown that they are less than optimal in revealing oral disease. The diagnostic accuracy of detailed narrow beam radiography (scanography) has been reported to be significantly better than intraoral periapical radiography for the observation of periodontal pathoses and at least as good as periapical radiography for detecting periapical lesions. The purpose of this study was to calculate and compare the effective doses and risk estimates from the use of detailed narrow beam radiography and intraoral radiography. With the use of a tissue equivalent human phantom and thermoluminescent dosimetry, the effective dose from detailed narrow beam radiography was found to vary from 5 to 35 microSv depending on the anatomic location of the image layer and intraoral radiography from 9 to 150 microSv depending on the type of survey. Effective doses of these magnitudes represent 0.6 to 18.8 days of equivalent natural radiation exposure and a probability for stochastic effects on the order of 0.37 to 10.95 x 10(-6).

A sensitometric comparison of Fuji Super HR-G and Kodak T-mat G panoramic films.

Film contrast, relative speed, and resolution of Fuji Super HR-G panoramic film were determined according to specifications of the American National Standards Institute and compared with those of Kodak T-mat G panoramic film. The films were simultaneously exposed by Kodak Lanex regular intensifying screens with time-scale sensitometry. Optical density was read with a digital densitometer, and characteristic curves were plotted and analyzed by polynomial and linear regression. The average gradients of the linear regression curves between 0.25 and 2.00 optical density units above base plus fog were taken as contrast (HR-G: 1.831, T-mat G: 1.712). Relative speed, when exposed with Lanex regular intensifying screens and calculated at 1.00 optical density unit above base plus fog, was 412 for HR-G. A speed of 400 was chosen for T-mat G to match Kodak consumer information. Resolution for both films was similar. These findings suggest that Fuji Super HR-G panoramic film develops similar contrast, speed, and resolution to Kodak T-mat G panoramic film.