The Incidence of Second Mesiobuccal Canals Located in Maxillary Molars with the Aid of Cone-beam Computed Tomography

INTRODUCTION

Many endodontic treatment failures in maxillary molars result from missed second mesiobuccal (MB2) canals. An MB2 canal orifice is present in as many as 95% of maxillary molars, but these canals are not always located during endodontic procedures. Additional tools, such as cone-beam computed tomographic (CBCT) imaging, may be needed to locate these canals in maxillary molars. Hence, the aims of this study were to investigate the frequency of use of CBCT imaging during the treatment of maxillary molars and to evaluate the influence of its use on the detection of MB2 canals.

METHODS

Endodontic treatment records, digital intraoral radiographs (when present), and CBCT images from all maxillary first and second molars treated at the University of Washington, Seattle, WA, between 2010 and 2014 (N = 886) were reviewed. Statistical analysis was performed to assess differences between the groups.

RESULTS

Overall, an MB2 canal was found in 55.8% of the maxillary molars studied, and CBCT imaging assisted in detecting 11.7% of these canals. CBCT imaging was used in 16.5% of the cases treated and was used significantly more for retreatment cases. CBCT imaging was used preoperatively in 5.6% of cases, and the data show that significantly more MB2 canals were located when a preoperative CBCT image was available. More MB2 canals were located in first molars without full-coverage crowns.

CONCLUSIONS

The data show that CBCT imaging is a valuable tool in locating MB2 canals. Based on the results of his study, the use of CBCT imaging could be warranted when treating maxillary molars.

Longitudinal Stability of Common TMJ Structural Disorders

The longitudinal course of temporomandibular joint (TMJ) disc displacement (DD) and degenerative joint disease (DJD) has never been conclusively described with magnetic resonance imaging and computed tomography, respectively. This 8-y observational study's objective was to assess the longitudinal stability of DD and DJD among 401 subjects. The Validation Project provided baseline measures; follow-up was performed in the TMJ Impact Project. With magnetic resonance imaging, 2 radiologists rendered a consensus diagnosis of normal/indeterminate, DD with reduction, or DD without reduction. Computed tomography consensus diagnoses included normal/indeterminate, grade 1 DJD, or grade 2 DJD. Radiologist reliability was assessed by kappa; a Hui-Walter model was used to estimate, after accounting for diagnostic disagreement, the frequency of diagnostic progression and reversal. Permutation tests were used to test the statistical influence of concurrent baseline diagnoses on diagnostic changes at follow-up. Of 789 baseline joint-specific soft tissue diagnoses of DD, 598 (76%) joints showed no change; 109 (14%) demonstrated progression; and 82 (10%) had reversal. Of 794 joints with baseline joint-specific hard tissue diagnoses of DJD, progression was observed in 122 (15%) joints, no change in 564 (71%), and reversal in 108 (14%). Radiologist reliability (kappa) was 0.73 (95% CI, 0.64 to 0.83) for DD and 0.76 (95% CI, 0.68 to 0.83) for DJD. After accounting for the influence of diagnostic disagreement, progression of hard tissue diagnoses in the right TMJ occurred in 15.2% of subjects (95% CI, 10.5% to 20.8%) and reversal in 8.3% (95% CI, 4.9% to 12.3%); results were similar for soft tissue diagnoses and the left TMJ. Concurrent baseline soft tissue diagnoses were associated with hard tissue diagnostic changes at follow-up ( P < 0.0001). Baseline hard tissue diagnoses showed no statistical association with soft tissue changes at follow-up ( P = 0.11). Longitudinally, 76% of baseline TMJ soft tissue diagnoses and 71% of the baseline hard tissue diagnoses remained stable. Diagnostic reversal and progression were confirmed for both soft and hard tissues.

Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: recommendations of the International RDC/TMD Consortium Network* and Orofacial Pain Special Interest Group†

AIMS

The original Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I diagnostic algorithms have been demonstrated to be reliable. However, the Validation Project determined that the RDC/TMD Axis I validity was below the target sensitivity of ≥ 0.70 and specificity of ≥ 0.95. Consequently, these empirical results supported the development of revised RDC/TMD Axis I diagnostic algorithms that were subsequently demonstrated to be valid for the most common pain-related TMD and for one temporomandibular joint (TMJ) intra-articular disorder. The original RDC/TMD Axis II instruments were shown to be both reliable and valid. Working from these findings and revisions, two international consensus workshops were convened, from which recommendations were obtained for the finalization of new Axis I diagnostic algorithms and new Axis II instruments.

METHODS

Through a series of workshops and symposia, a panel of clinical and basic science pain experts modified the revised RDC/TMD Axis I algorithms by using comprehensive searches of published TMD diagnostic literature followed by review and consensus via a formal structured process. The panel's recommendations for further revision of the Axis I diagnostic algorithms were assessed for validity by using the Validation Project's data set, and for reliability by using newly collected data from the ongoing TMJ Impact Project-the follow-up study to the Validation Project. New Axis II instruments were identified through a comprehensive search of the literature providing valid instruments that, relative to the RDC/TMD, are shorter in length, are available in the public domain, and currently are being used in medical settings.

RESULTS

The newly recommended Diagnostic Criteria for TMD (DC/TMD) Axis I protocol includes both a valid screener for detecting any pain-related TMD as well as valid diagnostic criteria for differentiating the most common pain-related TMD (sensitivity ≥ 0.86, specificity ≥ 0.98) and for one intra-articular disorder (sensitivity of 0.80 and specificity of 0.97). Diagnostic criteria for other common intra-articular disorders lack adequate validity for clinical diagnoses but can be used for screening purposes. Inter-examiner reliability for the clinical assessment associated with the validated DC/TMD criteria for pain-related TMD is excellent (kappa ≥ 0.85). Finally, a comprehensive classification system that includes both the common and less common TMD is also presented. The Axis II protocol retains selected original RDC/TMD screening instruments augmented with new instruments to assess jaw function as well as behavioral and additional psychosocial factors. The Axis II protocol is divided into screening and comprehensive self report instrument sets. The screening instruments' 41 questions assess pain intensity, pain-related disability, psychological distress, jaw functional limitations, and parafunctional behaviors, and a pain drawing is used to assess locations of pain. The comprehensive instruments, composed of 81 questions, assess in further detail jaw functional limitations and psychological distress as well as additional constructs of anxiety and presence of comorbid pain conditions.

CONCLUSION

The recommended evidence-based new DC/TMD protocol is appropriate for use in both clinical and research settings. More comprehensive instruments augment short and simple screening instruments for Axis I and Axis II. These validated instruments allow for identification of patients with a range of simple to complex TMD presentations.

Web-based calibration of observers using MRI of the temporomandibular joint

OBJECTIVES

Research diagnostic criteria for temporomandibular disorders (RDC/TMDs) were proposed in 1992 with the aim of standardizing and testing methods for diagnosing TMDs. RDC/TMDs have so far been lacking standardized methods for imaging and criteria for imaging diagnosis of disorders of the temporomandibular joint (TMJ). Criteria for disorders of the TMJ have recently been proposed for MRI. The aim of this study was to publish MR images of the TMJ on the web and to test the agreement of five observers using the criteria.

METHODS

20 cases of MRI of the TMJ were published on the web together with the criteria. The MR images were taken in closed and open mouth positions, and sagittal and coronal views. Five observers diagnosed disc position, disc shape, joint effusion and loose calcified bodies in the TMJ.

RESULTS

In all cases except one, three or more observers agreed upon the diagnosis. All agreed on whether a loose calcified body was present or not. The second best agreement was obtained for disc position in the sagittal view, where all observers agreed in 16 of the 20 cases. For disc position in the coronal view and the evaluation of the disc shape, observer agreement was lower.

CONCLUSION

Criteria were useful in order to standardize and simplify evaluation and thereby probably increase the diagnostic outcome among different observers for MRI of the TMJ. We recommend that the criteria be used internationally to facilitate comparisons between different studies.

A prospective randomized study on the immediate loading of mandibular overdentures supported by one or two implants: a 12-month follow-up report

PURPOSE

The purpose of the present study was to evaluate and compare treatment with mandibular overdentures supported by one or two implants placed and loaded immediately.

MATERIALS AND METHODS

Edentulous subjects with maxillary and mandibular complete dentures were recruited to participate in the study. All subjects received new maxillary and mandibular complete dentures, after which they were scheduled for implant surgery. Using a randomized sampling system, one or two implants were placed in the interforaminal area, and separate ball attachments were connected to the implants. The existing mandibular denture was relined, provided with retentive o-rings, and delivered the day of surgery. Subjects were seen for follow-up examinations after 3, 6, and 12 months, during which marginal bone levels and implant stability were measured. Survival rates were calculated and the data were analyzed statistically.

RESULTS

Thirty-six subjects (16 men and 20 women with a mean age of 53.2 years [range, 38 to 69 years]) received 55 implants. Seventeen subjects received one implant in the symphyseal area, and the other 19 received two implants in the canine positions. Ten implants in nine subjects failed during the observation period, and three subjects with two implants each withdrew from the study, resulting in a 12-month implant survival rate of 81.8%. Three subjects lost their only implant and one patient lost both implants. The remaining five subjects lost one of their two implants. Six of the failures occurred during the first month after placement.

CONCLUSION

Immediate loading of one or two separate implants by means of ball attachment-supported mandibular overdentures should be performed with caution, as a higher than expected implant failure rate was observed. No statistically significant differences in failure rates between the two groups were observed.

Research diagnostic criteria for temporomandibular disorders (RDC/TMD): development of image analysis criteria and examiner reliability for image analysis

OBJECTIVE

As part of the Multisite Research Diagnostic Criteria For Temporomandibular Disorders (RDC/TMD) Validation Project, comprehensive temporomandibular joint diagnostic criteria were developed for image analysis using panoramic radiography, magnetic resonance imaging (MRI), and computerized tomography (CT).

STUDY DESIGN

Interexaminer reliability was estimated using the kappa (kappa) statistic, and agreement between rater pairs was characterized by overall, positive, and negative percent agreement. Computerized tomography was the reference standard for assessing validity of other imaging modalities for detecting osteoarthritis (OA).

RESULTS

For the radiologic diagnosis of OA, reliability of the 3 examiners was poor for panoramic radiography (kappa = 0.16), fair for MRI (kappa = 0.46), and close to the threshold for excellent for CT (kappa = 0.71). Using MRI, reliability was excellent for diagnosing disc displacements (DD) with reduction (kappa = 0.78) and for DD without reduction (kappa = 0.94) and good for effusion (kappa = 0.64). Overall percent agreement for pairwise ratings was >or=82% for all conditions. Positive percent agreement for diagnosing OA was 19% for panoramic radiography, 59% for MRI, and 84% for CT. Using MRI, positive percent agreement for diagnoses of any DD was 95% and of effusion was 81%. Negative percent agreement was >or=88% for all conditions. Compared with CT, panoramic radiography and MRI had poor and marginal sensitivity, respectively, but excellent specificity in detecting OA.

CONCLUSION

Comprehensive image analysis criteria for the RDC/TMD Validation Project were developed, which can reliably be used for assessing OA using CT and for disc position and effusion using MRI.

Fractal dimension analysis of periapical reactive bone in response to root canal treatment

OBJECTIVE

Mathematical morphology and box counting were used to extract trabecular pattern and to evaluate changes of reactive bone following root canal treatment.

STUDY DESIGN

Periapical radiographs were digitized and processed with mathematical morphology operations known as skeletonization. The trabecular patterns resulting from this skeletonization process were further analyzed with fractal dimension (FD) analysis using the box-counting method. Two groups of regions of interest (ROI) were selected from 19 subjects for the analysis.

RESULTS

Seventeen patients in one group and 13 patients in the other showed decreased FD in the reactive bone region after clinically successful root canal treatment (RCT). Significant changes in FD were noted 6 months after RCT (P < .05). Kappa analysis indicated significant reproducibility between the 2 groups of ROIs.

CONCLUSIONS

Mathematical morphology combined with box counting showed decrease of FD in reactive bone regions after clinically successful endodontic treatment.

Head-and-neck organ doses from an episode of orthodontic care

INTRODUCTION

The high prevalence of orthodontic treatment in young people makes the associated radiation to the head and neck of potential public-health significance. In this study, we estimated secular changes (1963-2003) in age-specific organ doses associated with orthodontic care and collective organ doses in the United States in 1999.

METHODS

A survey of radiographic records at 1 university clinic was combined with published estimates to provide organ-specific radiation doses. Collective organ doses were estimated from the 1999 US Nationwide Evaluation of X-ray Trends and published orthodontic utilization surveys.

RESULTS

Before 1992, orthodontic care in a university setting was associated with mean doses of 7.0 milligrays (mGy) to the thyroid, 0.8 mGy to the red bone marrow, 2.7 mGy to the brain, 13.2 mGy to the salivary glands, and 5.1 mGy to the bone. After 1992, the doses decreased to 2.8 mGy to the thyroid, 0.3 mGy to the red bone marrow, 0.7 mGy to the brain, 6.2 mGy to the saliva glands, and 2.4 mGy to the bone. Around 1999, the collective doses associated with orthodontic care in the United States in patients less than 19 years of age were 400 Gy to the red bone marrow and 3800 Gy to the thyroid.

CONCLUSIONS

Orthodontic care, in part due to its high prevalence, potentially contributes significantly to the diagnostic radiation burden in those less than 19 years old in the United States.

Radiographs associated with one episode of orthodontic therapy

Obtaining lifetime diagnostic radiation histories in head and neck cancer studies is often challenging due to the almost universal lack of centralized registries on X-ray utilization in medicine and dentistry. Both the common nature of orthodontics and the young age at which orthodontics typically occurs make it important to quantify what diagnostic radiographs are typically taken during orthodontic therapy. The aim of this study was to assess the number and type of radiographic films associated with one episode of orthodontic therapy in an educational setting. Charts stored in an orthodontic clinic at one academic setting were randomly sampled, and the type and number of radiographic examinations were tallied for the 325 individuals who were in orthodontic therapy for at least one year. Being under orthodontic therapy for one or more years was associated with a median number of seven extra-oral radiographs and twenty-four intra-oral radiographic films. The extra-oral radiographs included three panoramic radiographs and three cephalometric radiographs. Less than 10 percent of the variability was explained by factors such as age, gender, calendar year, surgical orthodontic therapy, and duration of therapy. Head and neck cancer etiology studies should take into account the ionizing radiation during episodes of orthodontic care. The substantial variability in radiographic practices in orthodontics could be reduced by research into clinical utility and by establishing guidelines.

Thyroid shields and neck exposures in cephalometric radiography

BACKGROUND

The thyroid is among the more radiosensitive organs in the body. The goal of this study was twofold: (1) to evaluate age-related changes in what is exposed to ionizing radiation in the neck area, and (2) to assess thyroid shield presence in cephalometric radiographs

METHODS

Cephalometric radiographs at one academic setting were sampled and neck exposure was related to calendar year and patient's gender and age.

RESULTS

In the absence of shields, children have more vertebrae exposed than adults (p < 0.0001) and females have more neck tissue exposed inferior to the hyoid bone than males (p < 0.0001). The hyoid bone-porion distance increased with age (p <0.01). Thyroid shields were visible in 19% of the radiographs and depended strongly on the calendar year during which patient was seen (p-value <0.0001). Compared to adults, children were less likely to wear thyroid shields, particularly between 1973 and 1990 (1.8% versus 7.3% -p-value < 0.05) and between 2001 and 2003 (7.1% versus 42.9% -p-value < 0.05).

CONCLUSION

In the absence of a thyroid shield, children have more neck structure exposed to radiation than adults. In agreement with other reports, thyroid shield utilization in this study was low, particularly in children.

Digital imaging analysis with mathematical morphology and fractal dimension for evaluation of periapical lesions following endodontic treatment

OBJECTIVE

To see if a method for digitizing trabecular pattern of bone could be used to quantitatively evaluate changes in bone pattern following endodontic treatment of teeth with periapical osteolytic lesions.

STUDY DESIGN

Periapical radiographs were digitized and further processed with mathematical morphology operations known as skeletonization. The trabecular patterns resulting from this skeletonization process were further analyzed with fractal dimension analysis using box-counting.

RESULTS

The periapical area in digitized radiographic images showed fractal behavior. Twenty-five of 27 patients showed increase of the fractal dimension after root canal treatment. Significant changes of the box-counting could be noted 3 months after root canal treatment (P < .05).

CONCLUSIONS

Mathematical morphology operation and box-counting might be helpful in early detection of changes of periapical trabecular pattern after root canal treatment.

[The drug industry: a national issue]

Following up on a letter received from the Mrs. Nicole Fontaine, the Delegate Minister of Industry, requesting recommendations concerning the "serious threats" to the French drug industry, the Academy of Medicine auditioned the five leading French pharmaceutical firms and two foreign firms. Their complains led to proposals for six recommendations: recognize the strategic importance of the drug industry, conclude several years of contracts between the Economic committee on health products and the drug industry, facilitate clinical trails of drugs in France, favor relations between the national drug industry and university research centers, Inserm, Cnrs and the administration, encourage the development of biotechnology firms which represent one of the most promising areas of therapeutic research, propose the creation of an interministerial drug counsel presided by the Prime Minister to establish and implement a common national strategy.

Mucoepidermoid carcinoma in a young adult: recognition, diagnosis, and treatment and responsibility

Recognizing an abnormality is the first and most essential step when diagnosing a pathosis. All health care providers are responsible for evaluating suspicious symptoms and clinical and laboratory findings. Without a baseline evaluation, dentists cannot guarantee that patients are free of potentially serious disease. This article documents how the prognosis for and morbidity of cancer therapy may have been affected by the failure to recognize abnormal signs. Professional responsibility and liability for recognition of abnormality and subsequent diagnosis is emphasized.

Disk position and the bilaminar zone of the temporomandibular joint in asymptomatic young individuals by magnetic resonance imaging

OBJECTIVE

The purpose was to study the disk position of the temporomandibular joint (TMJ) in young individuals without any clinical signs or symptoms or history of internal derangement or degenerative joint disease and to study the features of the bilaminar zone of the TMJ in sagittal magnetic resonance (MR) images and the behavior of the bilaminar zone during jaw opening.

STUDY DESIGN

MR imaging examinations of 80 TMJs of 40 symptom-free healthy subjects (20 women and 20 men) with a mean age of 26.9 years formed the basis of this study.

RESULTS

In 33 of the 40 symptom-free subjects (82.5%), there was a normal relationship between disk and condyle at occlusion, whereas 5 individuals had unilateral disk displacement and 2 had bilateral disk displacement. The superior part of the bilaminar zone could be identified in all of the 40 symptom-free subjects. The inferior band of the bilaminar zone was identified bilaterally in 57.5% of individuals and unilaterally in 20%. In 9 subjects, the inferior band of the bilaminar zone could not be identified in any of the TMJs.

CONCLUSIONS

Disk displacement of the TMJ occurred in approximately 20% of the young individuals in this sample. The use of both sagittal and oblique coronal MR images is of importance for classification of the position of the disk in that the oblique coronal imaging plane rendered significant complementary information to that of the sagittal images. The identification of both the superior and the posterior band of the bilaminar zone must be considered new information. The superior band remained consistently in contact with the fossa at the open-mouth position.

["Cultural" barriers in the development of ambulatory surgery]

Several obstacles of different types seem to be a barrier to the promotion of "same day surgery": seizures of misinformed patients, local mentalities, reticence coming from different administrations, from control organizations also from general practitioners, as even a kind of reserve revealed by hospitals doctors. All these arguments are discussed and disproved.

The depiction of the bilaminar zone of the temporomandibular joint by magnetic resonance imaging

The existence of two distinct strata forming the bilaminar zone of the temporomandibular joint disc has recently been questioned. We report their successful demonstration using protondensity MR imaging. Our findings confirm earlier anatomical descriptions of the behaviour of the upper stratum during mouth opening.

A new coronal imaging plane for magnetic resonance imaging of the temporomandibular joint disc

We found that identification of an anterior displaced disc of the temporomandibular joint was difficult with traditional coronal oblique MR images. We describe the use of a new coronal oblique imaging plane which overcomes this problem.

Imaging of the temporomandibular joint: a position paper of the American Academy of Oral and Maxillofacial Radiology

Various imaging techniques for the temporomandibular joint are discussed with respect to uses, strengths, and limitations. An imaging protocol is outlined for evaluating patients with a wide variety of temporomandibular joint related signs and symptoms.

Detection of small differences in mass using a direct digital dental X-ray system

OBJECTIVES

To evaluate experimentally how in direct digital radiography heterogenous detector response may influence the depiction of small mass differences.

METHODS

A step wedge of a bone-simulating resin was imaged at 70 kVp using RadioVisioGraphy ZHR 32000. Exposure time and step wedge position on the detector varied. The pixel values of the stored images of the step wedge were converted to luminance values of the displayed images.

RESULTS

The relationship between pixel and luminance values was non-linear. The difference in luminance between adjacent steps varied with position of step wedge. Regardless of position, there was an increase in difference of luminance between steps with increasing exposure. A greater relative change in luminance was consequently seen in the thinner parts of the step wedge. The failure to perceive individual steps of the wedge in its thicker parts was related to insufficient relative change in luminance between steps.

CONCLUSIONS

The heterogeneous response of the detector resulted in a varying ability to depict small mass changes over the detector area.

Assessing the quality of radiographs accompanying biopsy specimens

According to a long-established protocol, biopsy specimens of bony lesions sent to the University of Washington Histopathology Service are accompanied by relevant radiographs. In this study, the authors evaluated the quality of 114 radiographs, both intraoral and panoramic, from 89 consecutive cases. The radiographs were judged on their clinical usefulness, rather than on criteria for technically ideal images, and on the severity, rather than the number, of errors. Only 33 percent of the panoramic radiographs were of acceptable quality, while the quality of the intraoral radiographs was markedly better. The most striking feature was the lack of three-dimensional radiographic coverage of the site of surgical exploration.

Digitizing of radiographs with a flatbed scanner

OBJECTIVES

Flatbed scanners with the transparency scanning option can be used to digitize radiographs. The physical performance of this type of scanner was studied with regard to the digitizing of radiographs, including the dynamic range, the reproducibility and the homogeneity.

METHODS

An Artix ArtiScan (Artix Technologies Inc., Milpitas, CA, USA) flatbed scanner with imaging editing software Aldus PhotoStyler (Aldus Corporation, Seattle, WA, USA) was used to digitize a stepped exposure image on Kodak T-MAT G films (Kodak, Rochester, NY, USA). The stepped exposure image was scanned at various locations and with different scanning settings. The pixel values of the resulting digital images were analysed. The stepped exposure image was also scanned by a laser densitometer to measure the optical densities of the steps on the film for comparison.

RESULTS

Using the default scanning settings, the digitized images had pixel values distributed in a narrower range than that of the optical density values of the films. The range of the pixel values was widened by increasing the scanning time. Even then, the resulting pixel value profile was not identical to the optical density profile measured on film. The characteristic curve of this digitizing system was steeper than that of the film. Different pixel value distributions were obtained when the stepped exposure image was scanned at different positions on the scanning field, and when scans were obtained at different times. Reproducible results could be acquired when the images were scanned in the same area of the scanning field without changing the scanning settings and after the power had been on for a few minutes.

CONCLUSIONS

In order to obtain digitized radiographs of any reliability from flatbed scanners, these should be carefully calibrated at the operating conditions.

Linear unsharp mask filtering of linear cross-sectional tomograms of the posterior mandible

Linear unsharp mask filtering is a digital image processing technique which can enhance diagnostic information by subtracting from the original image the linear blur which was formed in the direction of the linear tomographic movement. It was applied to linear cross-sectional tomograms of the posterior mandible aiming at retrieving cross-sectional outline information. This study demonstrated that the current Orthophos Program 16 with a 6.72 degrees tomographic angle does not provide accurate cross-sectional outline information of the posterior mandible. Linear unsharp mask filtering of these images also failed to provide more information. A larger tomographic angle of 10 degrees was employed with the Polytome to simulate the modified Program 16 with a wider beam. The resulting tomographic images showed better defined cross-sectional outlines, and after the linear unsharp mask filtering, the outlines were more readily retrieved. In order to get cross-sectional outline information of the posterior mandible, the tomographic angle of the Orthophos program 16 should be increased to more than 10 degrees which can be achieved by increasing the width of the x-ray beam.

Frequency domain analysis of cross-sectional images of the posterior mandible

The Siemens Orthophos (Siemens, München, Germany) is a panoramic machine that uses a microchip to control the movements of the radiation source and film. Several programs are available for different views of the facial skeleton and associated structures. Program 16 is dedicated to cross-sectional imaging of the posterior mandible. Three millimeter cross-sections were cut from 12 cadaver specimens of the mandible. These sections were imaged separately by contact radiography, 48 degrees hypocycloidal tomography of Philips Polytome (Philips-Massiot, Paris, France), and program 16 of the Orthophos panoramic machine. Program 16 of the Orthophos was also used to image the cross-sections after they were glued back together with the surrounding parts of the specimens. Four different images of the cross-sections were thus obtained. The contact radiographs were used as gold standards. Frequency domain analysis, which was used to compare the images resulting from each imaging modality, demonstrated that useful diagnostic information was in the range of 0.12 to 0.60 cycles/mm for the contact radiographs. In spite of differing tomographic angles for the Orthophos program 16 and the hypocycloidal tomography, the images of the 3 mm cross-sections showed similar frequency distribution. However, the Orthophos Program 16 did not produce diagnostically useful images when the cross-sections were imaged with the surrounding parts of the specimens probably because of the narrow tomographic angle used for this program. These images had strong low to medium frequency components compared with the gold standard images. These results suggest that diagnostically more useful images with the Orthophos might be obtained by increasing the tomographic angle.

Modulation transfer function of a digital dental x-ray system

An impulse train method to control aliasing was used to measure the modulation transfer function of a digital dental x-ray system (RVG 32000 ZHR, Trophy Radiologie, Vincennes, France). The detector of this system is composed of an intensifying screen, a fiber optics taper, and a charged couple device chip. The modulation transfer function could not be measured by impulse method such as the line spread function or edge response function because of aliasing from undersampling of the digital system. The system modulation transfer function was difficult to recover at the spatial frequencies smaller than the Nyquist frequency. The modulation transfer function beyond the Nyquist frequencies was impossible to recover in this study.

Detector response and exposure control of the RadioVisioGraphy system (RVG 32000 ZHR)

The RadioVisioGraphy system (RVG 32000 ZHR) was studied with respect to some physical properties including the precision and linearity of the exposure control and the detector response to x-rays. The x-ray unit was found to yield repetitive exposures that are precisely controlled by the CCX timer. A "preheat" and an "after exposure" period were noticed, and their resulting x-ray exposures were measured. Two RVG detectors were compared for their responses with x-rays. The differences between the detectors were insignificant. However, inhomogeneous detector responses were found in both of the detectors; with the same exposure, the central parts of the detectors yielded lower pixel values than the peripheral parts. A calibration equation was developed to correct for the inhomogeneity.

Comparison of panoramic and intraoral radiography for the diagnosis of caries and periapical pathology

Panoramic and intraoral radiographs from 400 consecutive patients were compared for their ability to demonstrate periapical pathology and caries. Two hundred panoramic radiographs were exposed with the rotational technique and 200 with the intraoral X-ray tube technique. Periapical osteolytic and sclerotic lesions as well as approximal caries were recorded independently by two observes. Agreement with intraoral radiographs for periapical osteolytic lesions was, on average, 63% for the rotational and 55% for the intraoral X-ray tube technique and for sclerotic lesions 40% and 36%, respectively. The agreement varied with tooth type and lesion size. When teeth without periapical lesions were also included in the comparisons, the values for agreement were over 96%. Interobserver agreement for periapical osteolytic lesions was 61% for the rotational and 56% for the intraoral X-ray tube technique. The corresponding values for sclerotic lesions were 29% and 23%. Intraobserver agreement for periapical osteolytic lesions was 71% for the rotational and 67% for the intraoral X-ray tube technique. The corresponding values for sclerotic lesions were 46% and 56%. Agreement with intraoral radiographs for enamel caries was, on average, 21% for the rotational and 27% for the intraoral X-ray tube technique and for dentinal lesions 44% and 53%, respectively. When caries-free approximal surfaces were also included in the comparisons, the values for agreement were over 95%. It is concluded that panoramic and intraoral radiography perform equally well as diagnostic tools for the detection of periapical lesions, although the results are not identical.(ABSTRACT TRUNCATED AT 250 WORDS)

Decision making in radiographic imaging

In 1987, the U.S. Department of Health and Human Services issued guidelines for prescription of dental radiographic examinations, and although these recommendations have been reprinted in several widely circulated publications, it seems that the adoption of these guidelines is far from common, even among U.S. dental schools. The recommended criteria are founded on the existing knowledge of prevalence and progression of the most common dental diseases and on the fact that occult diseases within the jaws are uncommon. There are, however, other factors that may influence the decision on the time and extent of a radiographic examination, which may lead to deviations from the suggested guidelines. These factors include: education, peer influence, patient's preference, legal considerations, the dentist's field of interest or specialty, the training of the staff, and practice routine. The diagnostic interpretation of radiographs is far from a completely objective process, even if it is a question as simple as the presence and/or extent of a carious lesion. Numerous studies have shown a large variation among observers, both with regard to the occurrence and extent of carious lesions, in bite-wing radiographs. Caries diagnosis is only one example of many situations where significant observer variation is found. The more complex the diagnostic task, the more variation can be expected. The effect of observer variation on treatment decisions regarding carious lesions is used as an example of the problems encountered daily in the dental practice.

Image resolution in the midsagittal plane of the Orthopantomograph-10 using Lanex regular and T-Mat G screen-film combination

Image resolution was measured in the midsagittal plane of the Orthopantomograph-10 with the use of Lanex regular and T-Mat G screen-film combination. A thin platinum edge phantom was used to obtain images for calculation of the edge response functions. Subsequently, line spread functions and modulation transfer functions of the system were calculated. Noise equivalent passband values, which were expressed in line pairs per millimeter, were derived to describe the image resolution. The noise equivalent passband values derived in this study were generally smaller than those reported in a previous study. The width of the image layer was found to be uniform at different vertical levels.

Agreement between panoramic and intra-oral radiography in the assessment of marginal bone height

Panoramic and intra-oral radiographs from 400 consecutive patients were evaluated for the assessment of the marginal bone height. Two hundred panoramic radiographs were exposed with the rotational technique and 200 with the intra-oral X-ray tube technique. Measurements of the approximal marginal bone level were independently performed by two observers. Complete agreement between panoramic and intra-oral radiographs was, on average, obtained in 55% and 49% of the sites, respectively. When the criterion for agreement was widened to include recordings with a difference of +/- 1 mm, the agreement was on average 87% irrespective of the techniques compared. The agreement varied with tooth type and severity of the marginal bone loss. Angular bony defects and furcation involvements were recorded separately. For angular bony defects there was a variation in agreement from 33% to 46% for the rotational technique and from 35% to 51% for the intra-oral X-ray tube technique depending on localization. Furcation involvements of the molars were equally recorded in 60% and 59%, respectively, but in only 12% and 28% for the upper premolars. Interobserver agreement was 58% for the intra-oral radiographs, 60% and 59% for the two panoramic techniques. Mean intra-observer agreement was 68%, 66% and 68%. It is concluded that panoramic radiography can often be used for the assessment of marginal bone loss alone, supplemented when necessary by intra-oral radiographs.

Comparison between panoramic and periapical radiography in the diagnosis of periapical bone lesions

The diagnostic accuracy of panoramic and periapical radiography was compared by five oral radiologists who assessed the periapical status of 117 teeth evenly distributed throughout the jaws with a 50% probability that either an osteolytic or sclerotic lesion was present. Receiver operating characteristic (ROC) analysis demonstrated no overall significant difference between panoramic and periapical radiography. However, for sclerotic lesions and for all lesions on maxillary premolars and mandibular molars periapical radiography was significantly superior (P less than 0.001); it was also superior for osteolytic lesions in the maxilla as well as for the lesions on mandibular premolars but with a smaller significant difference (P less than 0.05).

Smoking habits and tooth loss in Swedish women

A longitudinal population study of 1462 women, aged 38-60, was started in Gothenburg, Sweden, in 1968-69. In univariate analysis of the results from 1968-69, smokers were found to have a significantly lower number of remaining teeth than non-smokers had. The differences between smokers and non-smokers with respect to edentulousness and number of remaining teeth was further accentuated 12 yr later. The mean number of teeth lost during the 12-yr follow-up period was 3.5 among smokers and 2.1 among non-smokers, i.e. 67% higher among smokers than among non-smokers. The associations were independent of age, education, socio-economic group, marital status, frequency of toothbrushing, and frequency of visits to a dentist. It is concluded that smoking seems to play an important role as far as tooth loss is concerned.

Number of amalgam tooth fillings in relation to subjectively experienced symptoms in a study of Swedish women

There has been a lot of discussion concerning the possible influence of amalgam tooth fillings on different symptoms and complaints. Information on this topic could be obtained from 1024 dentulous women aged 38-72, participants in a population study of women in Gothenburg, Sweden, who answered a questionnaire with 30 specific questions concerning different symptoms and complaints. The answers were related to number of tooth surfaces restored with amalgam. Due to the sampling method and the high participation rate, the participants were representative of dentulous women of the same age in the general population. No positive correlations were found between number of amalgam fillings and number of symptoms, nor between number of amalgam fillings and prevalence of specified single symptoms or complaints. On the contrary there were a number of age-matched significant correlations in the opposite direction, which means that women with a high number of amalgam fillings reported a lower number of symptoms and complaints than women with a low number of amalgam fillings. These inverse relationships between number of amalgam fillings and different symptoms and complaints usually disappeared, when number of teeth was taken into consideration as a background variable. The inverse relationships with abdominal pain and poor appetite were, however, independent of both number of teeth and socioeconomic status as based on multivariate analysis. This study does not support the view of a correlation between amalgam fillings and symptoms and complaints, at least not on a population level.

[Gastroesophageal reflux in asthmatic and chronic bronchitis patients]

To determine the relationship between gastroesophageal (GE) reflux and pulmonary disease, we studied 21 asthmatics, 30 chronic bronchitics, 6 patients with GE reflux and no pulmonary symptoms, and 10 control subjects; GE reflux was diagnosed by pH monitoring and GE scintiscanning. Frequency of GE reflux in the asthmatics was 57%; in chronic bronchitis it was 56%. Pulmonary function tests did not show any differences between patients with or without reflux. The GE reflux episodes were more numerous but shorter in asthmatics than in chronic bronchitis. Patients with digestive symptoms alone were no different from chronic bronchitis with respect to reflux. The mechanism whereby reflux triggers pulmonary problems was investigated using the following 2 tests: scintiscan for pulmonary aspiration, and esophageal acid infusion (0.1N HCI). Six pulmonary aspirations were detected. Only asthmatics, with or without reflux, showed any significant variations in maximal expiratory flow at 50% and 25% of VC after HCI infusion. Thus, our results show that asthmatics differ from bronchitis patients by the characteristics of their reflux.

Relationship of mandibular condylar position to dental occlusion factors in an asymptomatic population

This article investigates the influence of occlusion on condylar position as seen on TMJ tomograms in a group of 44 young adults with no histories of orthodontic or occlusal therapy and no objective signs of masticatory dysfunction; the sample was screened from a population of 253 students. Nonconcentric condylar position at ICP was a feature of Class II malocclusion with significantly more anterior positions in Class II, Division 1 than in Class I. Condylar position was unrelated to the amount of sagittal RCP-ICP slide, although most slides were less than 0.5 mm. The frequency of lateral slides was low, but was mildly related to bilaterally asymmetric condylar positions. Position was unrelated to the degree of overbite, which ranged from 0 to 10 mm. Bilateral condylar position asymmetry was not related to the direction of dental midline discrepancy, which ranged from 0 to 2 mm. No open bites or mandibular overjets were seen in this asymptomatic normal sample.

Gastroesophageal reflux in patients with asthma and chronic bronchitis

To determine the relationship between gastroesophageal (GE) reflux and pulmonary disease, we studied 21 asthmatics, 30 chronic bronchitics, 6 patients with GE reflux and no pulmonary symptoms, and 10 control subjects; GE reflux was diagnosed by pH monitoring and GE scintiscanning. Frequency of GE reflux in the asthmatics was 57%; in the chronic bronchitics it was 56%. Pulmonary function tests did not show any differences between patients with or without reflux. The GE reflux episodes were more numerous but shorter in asthmatics than in chronic bronchitics. Patients with digestive symptoms alone were no different from chronic bronchitics with respect to reflux. The mechanism whereby reflux triggers pulmonary problems was investigated using the following 2 tests: scintiscan for pulmonary aspiration, and esophageal acid infusion (0.1N HCl). Six pulmonary aspirations were detected. Only asthmatics, with or without reflux, showed any significant variations in maximal expiratory flow at 50% and 25% of VC after HCl infusion. Thus, our results show that asthmatics differ from chronic bronchitics by the characteristics of their reflux.

Variation in condyle-fossa relationships according to different methods of evaluation in tomograms

Mandibular orthopedic diagnosis is frequently based on observation of radiographic nonconcentric condyle-fossa relationships, but the definition of normal and abnormal positions is, in part, obscured by the several different methods used to assess condyle position and the absence of intermethod comparisons. This study compared the measurement and expression of condyle position in tomograms according to subjective evaluations and linear and area measurement of the interarticular space by use of a microcomputer and graphics tablet. Area analysis showed the least concordance with the subjective evaluation. Linear measurement of the subjective closest anterior and posterior interarticular space presented the greatest concordance, had low interobserver variation, and was considered clinically relevant to the functional thickness of the center of the articular disk.

Jaw morphology in edentulous individuals: a radiographic cephalometric study

The jaw morphology in the mandible and maxilla was studied by cephalometric analysis in two groups of edentulous subjects and in two groups of individuals in possession of all teeth. The predominating facial type in these groups was the orthognathic type. The alveolar bone height differed significantly between men and women in the edentulous groups but not in the subjects in possession of all teeth. Thus, there seemed to be a sex difference in alveolar bone diminution after extraction of all teeth. The gonial angle was significantly greater in both men and women in the edentulous groups than in either sex in the groups in possession of all teeth. Thus, the basal bone morphology in the mandible seemed to be changed in the same manner in both sexes in the edentulous groups after extraction of all teeth, in contrast to the alveolar bone diminution. Indications were found that the gonial angle might be age related. The chin angle as such was found to be less than 60 degrees in the majority of edentulous individuals which makes this value seem to be of minor importance when selecting edentulous individuals for surgical deepening of the vestibular sulcus.

Assessment of mandibular condyle position: a comparison of transcranial radiographs and linear tomograms

Transcranial radiographs are frequently used to assess condyle-fossa relationships. However, their validity in representing condyle position has been questioned. Intermethod comparisons were performed between methods assessing condyle position by subjective evaluation and by linear and area measurement of the interarticular space. Linear measurement of the subjective closest anterior and posterior interarticular space and subjective evaluation were the mutually preferred methods in both transcranial radiographs and tomograms. Statistically significant correlations were shown (p less than 0.05) for condyle position between pairs of clinical transcranial radiographs and linear tomograms of the same temporomandibular joints. However there was a qualitative concordance in assessed posterior concentric and anterior positions in only 80% of the pairs, and a full concordance in the degree of condylar displacement was found in only 60% of the cases. Although still clinically helpful, the use of transcranial radiographs to monitor small changes in condylar position relative to the tomogram was questioned.

Comparison of xeroradiographs and film for detection of periapical lesions

Xeroradiographs and Kodak Ektaspeed film were compared with Kodak Ultraspeed film for their ability to reveal periapical lesions. Cadaver specimens containing teeth which were normal or demonstrated periapical inflammatory disease were used as the test objects. These specimens were first radiographed using xeroradiographic plates or film. Following radiography, histologic analysis revealed the true presence or absence of disease. Ten oral radiologists scored all xeroradiographic and film images of the specimens for the presence of periapical disease. In general, the observers detected about 70% of the cases with periapical disease, while simultaneously considering about 10 to 15% of the normal surfaces to be abnormal. Receiver-operating-characteristic (ROC) analysis of the radiographic decisions revealed little difference in the diagnostic performance of the observers using the various image receptors, although both types of film and low-contrast xeroradiographs viewed in transmitted light were all more useful than low-contrast xeroradiographs viewed in reflected light. In terms of patient dose, both xeroradiographic images and Ektaspeed film are preferred over Ultraspeed film.

The temporomandibular joint in ankylosing spondylitis. Correlations between subjective, clinical, and radiographic features in the stomatognathic system and effects of treatment

One hundred individuals with ankylosing spondylitis (AS) and a comparison group comprising 57 individuals without joint symptoms or disease were studied for correlations between subjective, clinical, and radiographic features in the stomatognathic system and the short-term effect of occlusal splint therapy. There was a correlation between radiographic findings in the temporomandibular joint (TMJ) and subjective and clinical symptoms from the stomatognathic system in individuals with AS but not in the comparison group. There were also more and stronger correlations between clinical signs of TMJ involvement and subjective and other clinical symptoms from the stomatognathic system in the individuals with AS than in the comparison group. There are thus strong indications that the subjective symptoms, the clinical signs, and the radiographic findings in the TMJ of the individuals with AS were caused mainly by this joint disease. The short-term effect of treatment with occlusal splints was investigated in seven of the individuals with AS, who had clinical dysfunction index II or more in accordance with Helkimo. No statistically significant improvement of the subjective or clinical symptoms from the stomatognathic system was found, although a reduction of clinical symptoms was noted in five of the seven individuals.

TMJ pain and dysfunction: relation between clinical and radiographic findings in the short and long-term

Clinical examination of the stomatognathic system and radiographic examination of the temporomandibular joints (TMJ), including the submentovertical, the oblique lateral transcranial and the transmaxillary projections, were performed in 104 patients with TMJ pain/dysfunction. Seven years later these patients had a new clinical examination and 54 of them were radiographed again. Another 20 patients not primarily radiographed were also recalled after 7 yr and examined clinically and radiographically. The radiographic findings were correlated with the reported symptoms and clinical findings. Only a few statistically significant correlations were found. The initial clinical dysfunction, estimated with the aid of the Helkimo dysfunction index, was positively correlated with the radiographic findings at the follow-up. The most important clinical variables in this respect were tenderness to palpation of the joint and decreased mobility. Crepitation was associated with changes in the structure and shape of the condyle. Clicking was correlated with a posterior displacement of the condyle. The number of occluding pairs of teeth was related to changes in the TMJ structure and shape also when age was considered as a confounding factor. Radiographic changes of the TMJ develop late and are often absent in the acute phase. An early radiographic examination is therefore of less diagnostic importance in this respect, but serves the purpose of excluding other pathologic conditions.