Fractal dimension on dental radiographs

OBJECTIVES: (1) To compare fractal dimension (FD) from periapical radiographs with FD from panoramic radiographs; (2) to correlate FD with cortical thickness and morphology; and (3) to correlate FD with a reported history of osteoporotic fractures. METHODS: Information on fracture and smoking history was obtained by a telephone interview with 281 elderly (>60 years of age) patients who had periapical and panoramic radiographs exposed on the same date. FD was measured in several locations on both types of radiograph. Mandibular cortical thickness and morphology were obtained from the panoramic radiograph. RESULTS: FD measured in the mandible was lower than FD in the maxilla. Same-jaw measurements had a higher correlation than same-side measurements. FD measured on panoramic radiographs was lower than FD from periapical radiographs. There was a negative correlation between cortical thickness and FD. FD was higher in subjects with more mandibular cortical porosities and resorption. The mean panoramic FD from subjects with a history of osteoporotic fractures was significantly higher, after adjusting for smoking, gender, age, height and weight. CONCLUSIONS: FD measured on panoramic radiographs is lower than FD measured on periapical radiographs. FD is higher in both types of radiograph in subjects with a thinner, severely eroded mandibular cortex and a history of osteoporotic fractures. This study confirms other reports that FD increases when bone mass decreases. In addition, it suggests that panoramic radiographs can be used as a possible alternative for the measurement of FD to periapical radiographs.     

Individualized periapical radiography determined by clinical and panoramic examination.

The efficiency of panoramic radiography compared with full-mouth periapical examination is an unresolved problem. The diagnostic yield of periapical lesions when the clinical signs and symptoms and the findings from a panoramic radiograph served as the basis for an individualized periapical radiographic examination was studied. Two hundred patients were examined clinically and radiographically. The periapical status was assessed step by step with access to increasing numbers of radiographs. For the clinical examination, the sensitivity was 0.24, the positive predictive value 0.62, the specificity 0.98, the negative predictive value 0.90 and the likelihood ratio for the positive test result 12. For radiographs indicated by the clinical examination plus the panoramic radiograph and selected periapical radiographs, both the sensitivity and the positive predictive value were 0.91, the specificity and the negative predictive value 0.99 each and the likelihood ratio was 91. False findings were twice as frequent in the upper as in the lower arch and particularly found in the incisor and premolar regions. In 30% of the patients no periapical radiograph was needed to supplement the panoramic radiograph. In the other patients, two supplementary periapical radiographs were needed on average. We conclude that the information obtained from the clinical and panoramic examinations supplemented with no more than two periapical radiographs will result in a high diagnostic yield on the periapical status.     

Marginal bone in periodontal disease: an evaluation of image quality in panoramic and intra-oral radiography

Five observers assessed the panoramic and full-mouth (14 periapical and four posterior bitewing) radiographs of 20 patients each for the ability to interpret and measure the marginal bone level. The image quality of each site was classified as excellent, acceptable or unacceptable. Depiction errors affecting interpretability and measurability were also noted. In the upper arch, the frequency of uninterpretable and non-measurable sites was almost equal for panoramic and periapical radiography. Image quality was better with periapical radiography in the lower arch. In the posterior regions of both arches, more sites could not be measured from panoramic compared with bitewing radiographs. Due to overlapping the distal surface of the maxillary canine and the mesial surface of the first maxillary premolar could often not be interpreted in either panoramic or periapical radiographs, but infrequently in the bitewings. In the lower arch, the most frequent depiction error was inadequate density in the incisor region of panoramic radiographs. On the basis of these results, we proposed that in clinical practice the panoramic radiograph can be supplemented with individually selected periapicals. In epidemiological studies, the panoramic radiograph should be combined with a premolar bitewing radiograph.     

Survey of radiographic practices for periodontal disease in UK and Irish dental teaching hospitals

OBJECTIVES: To assess current radiographic practices in dental teaching hospitals for the management of patients with periodontal diseases. METHODS: All 17 dental teaching hospitals in UK and Ireland were sent a questionnaire on radiographic equipment and radiograph selection currently used for assessment of patients with destructive periodontal diseases. Opinions were recorded for advantages and disadvantages of the most frequently used radiographic views. RESULTS: A 100% response rate was achieved. All hospitals used panoramic and specific periapical radiographs as one of their radiographic regimes for patients with periodontal disease. Fifty-three per cent of respondents most frequently took panoramic and selected periapical radiographs. Twenty-four per cent took full mouth periapical radiographs (FMPAs) most frequently and 18% took a panoramic radiograph alone. Twenty-four per cent of hospitals operated a protocol for selection of radiographs for periodontal patients. CONCLUSIONS: The most commonly used views taken to assess periodontal status are panoramic radiographs with selected periapicals. Few hospitals operate a protocol for prescribing radiographs.     

Observer performance in the assessment of periapical pathology: a comparison of panoramic with periapical radiography.

Observer performance in the assessment of the periapical pathology from panoramic and periapical radiography was examined. Five endodontists, five general practitioners and five oral radiologists were asked to assess the periapical status of 117 teeth. The observers assessed the panoramic and periapical radiographs of the teeth, which were evenly distributed throughout the jaws with a 50% probability that either an osteolytic or sclerotic lesion was present. The results of the comparison between panoramic and periapical radiography were influenced by the selection of observers. When the oral radiologists acted as observers, the mean P(A) value for periapical radiography was higher than for panoramic radiography (P less than 0.001), resulting in periapical radiography presenting a higher overall diagnostic accuracy than panoramic radiography for all 15 observers (P less than 0.01). There was, however, no difference between panoramic and periapical radiography when the two groups of endodontists and general practitioners acted as observers. The comparison of the three groups of observers showed no difference between their diagnostic accuracy when assessing panoramic radiographs. With periapical radiography, the oral radiologists demonstrated a higher diagnostic accuracy than the endodontists (P less than 0.05). The observers in each group with the highest diagnostic accuracy also had the highest intra-observer agreement. The mean intra-observer agreement of the five general practitioners was higher than those of the other two groups of observers for panoramic radiography. For periapical radiography, the mean agreement rates of the groups were comparable.     

Osteochondromas of the mandibular condyle: variance in radiographic appearance on panoramic radiographs

OBJECTIVES: Osteochondromas are frequently found in the general skeleton, but are rare in the mandibular condyle. Radiographically, most reports describe osteochondromas as a mushroom-shaped bony enlargement capped with cartilage on the condylar surface. However, the radiographic appearance of this lesion on the panoramic radiograph has rarely been studied. The purpose of this article is to increase the radiographic knowledge of mandibular condylar osteochondroma and facilitate making an exact diagnosis through observing the lesional appearance on panoramic radiograph. METHODS: The panoramic radiographs of 12 cases of mandibular condylar osteochondromas were reviewed. All cases were obtained from the Department of Oral Radiology, West China College of Stomatology, Sichuan University, between 1988 and 2006. The final diagnoses of all cases were based on pathology. RESULTS: Osteochondromas may arise on different areas around the mandibular condyle and present diverse appearances on panoramic radiograph. CONCLUSIONS: The mandibular condylar osteochondromas may show different growth positions encircling the condyle and exhibit varying shapes on panoramic radiograph. These features will help us to increase cognition of the lesion and make an exact diagnosis.     

Clinical evaluation of the effects of radiographic distortion on the position and classification of mandibular third molars

OBJECTIVE: Panoramic radiographs are routinely employed for surgical planning of unerupted third molars. The objective of this study was to evaluate distortions in the position of mandibular third molars on panoramic radiographs. MATERIALS AND METHODS: Panoramic radiographs of 14 patients with indication for extraction of the mandibular third molars were used. Transurgical impressions of the crowns of the teeth to be extracted and adjacent second molars (n=19) were achieved with addition silicone and poured with type IV plaster for comparison of the inclinations of the third molars on the radiographs and study casts. RESULTS: There was a mean difference of -5.37 degrees between the position of the third molar on the panoramic radiograph and on the study cast (standard deviation 1.46, P<0.05, Student's t-test). CONCLUSION: There is distortion in the position of teeth on the panoramic radiograph, which may influence the surgical planning; however, this does not invalidate it as the main tool for diagnosis and surgical planning of mandibular third molars.     

Radiological findings in an unusual osteosarcoma in the maxilla

An unusual case of osteosarcoma of the maxilla, which was initially diagnosed as fibrous dysplasia on the basis of the clinical CT and histopathological findings, is presented. However, panoramic and periapical radiography suggested a malignant neoplasm. After surgery, the tumor was diagnosed histopathologically as a low-grade osteosarcoma. We conclude that panoramic and periapical radiographs are important adjuncts and should be included in any investigation of the jaws where CT scanning is unable to differentiate between osteosarcoma and fibrous dysplasia.     

Diagnostic accuracy of panoramic radiography in the detection of calcified carotid artery

OBJECTIVES: The purpose of this study was to assess the diagnostic accuracy of the panoramic radiograph in the detection of carotid artery calcification using CT as the gold standard. METHODS: 110 dental patients (average age 65.2 years, range 50-82 years) with both panoramic radiographs and CT scans available were selected for the evaluation of carotid artery calcification. Two oral and maxillofacial radiologists interpreted the panoramic radiographs for the presence of carotid artery calcification. CT scans were independently interpreted by a neuroradiologist. RESULTS: The accuracy of panoramic radiographs in the detection of carotid artery calcification was 62.3%. The sensitivity and the specificity were 22.2% and 90.0%, respectively. CONCLUSIONS: Panoramic radiography has a moderate diagnostic accuracy in the detection of carotid artery calcification, but the sensitivity is low.     

Validity of using a panoramic radiograph for initial dental classification of Army recruits

OBJECTIVE: The objective of this study was to examine the validity of classifying Initial Entry Training (IET) soldiers into dental fitness classification 2 or 3 based solely on examining panoramic radiographs. MATERIALS AND METHODS: The dental readiness classification, derived from a clinical screening examination versus a panoramic radiological examination, was compared for 1,050 Fort Sill Basic Training recruits during a 1-month period. The dentist who reviewed the panoramic radiograph and determined a dental classification was blinded to the earlier dental classification from the clinical examination. The Spearman's rank order correlation test was used to determine if a statistically significant correlation existed between classifications based on the clinical examination versus classification by review of the panoramic radiograph alone. RESULTS: The project identified that 18% (n = 186) and 23.7% (n = 249) of the sample population had at least one class 3 condition identified from the clinical screening examination and the panoramic radiograph review, respectively. Of the 186 dental fitness category 3 conditions identified from the routine dental screening, 81.7% (152) of them were also identified from the review of the panoramic radiograph. Spearman's rank order correlation test statistic was 0.633 for a p < 0.001, indicating a statistically significant correlation in the identification of IET soldiers with class 3 conditions using a screening examination with a review of the panoramic radiograph. CONCLUSIONS: The findings of this study suggest that panoramic radiograph review can identify IET soldiers with dental fitness category 3 conditions and implies that a policy change may be prudent to allow this type of initial classification.     

A method to maintain a constant magnification factor throughout the exposure of rotational panoramic radiographs

The magnification factor can be held constant throughout the exposure of a panoramic radiograph by maintaining the physical centre of rotation equidistant from the central plane of the image layer. This may be accomplished with computer-controlled movement patterns while the effective centre of rotation follows a path selected to provide an optimal projection of the jaws. Theoretical considerations for creation of a constant magnification factor are presented and the practical implementation of the technique in a commercially available device (OrthOralix SD, Philips, Monza, Italy) is described. This technique minimizes distortion in panoramic radiographs and makes horizontal measurements possible in certain selected cases.     

Comparing the accuracy of panoramic and intraoral radiography in the diagnosis of proximal caries

OBJECTIVES: The purpose of this study was to compare the diagnostic accuracy of panoramic and intraoral radiographic surveys in the diagnosis of proximal caries according to the different dental regions (maxillary and mandibular incisor, canine, premolar and molar). METHODS: In this study, full mouth series and panoramic radiographs of 79 patients were used. The radiographs were evaluated for proximal caries by three observers. The diagnostic accuracy of radiographic surveys for each dental region was assessed by means of receiver operating characteristic (ROC) curve analysis. RESULTS: Full mouth series was the most efficient method in the diagnosis of caries for incisor and canine teeth. However, full mouth series and combination of panoramic plus bitewings had similar diagnostic accuracy for premolar and molar teeth. CONCLUSIONS: Panoramic survey alone was not sufficient for the diagnosis of proximal caries for the entire dentition. The combination of panoramic plus bitewing plus anterior periapical survey exhibited a diagnostic accuracy for proximal caries that was comparable with full mouth series.     

Reliability of computational measurement of the condyles on digital panoramic radiographs

Objective

The aim of this study was to evaluate the reliability of a computational method for assessing three condylar measurements on digital panoramic radiographs: condylar height, area and perimeter.

Methods

A computer calculation of the area, the perimeter and the height of 34 condyles was determined on digital panoramic radiographs taken from 17 patients. The test–retest precision of measurements calculation was estimated using an intraclass correlation coefficient (ICC) and Dahlberg''s formula at 2 week intervals on the same radiograph to assess intraobserver precision and on two radiographs (RX1 and RX2) to assess the radiographic procedure precision. Changes between measurements on RX1 and RX2 were estimated using paired t-tests to detect systematic errors.

Results

Precision of all indices was very high when measurements were made on the same radiograph, thus confirming good reliability for the present computational measuring method. The precision was lower when two different radiographs were compared but was still within an acceptable range of tolerance. There were no statistically significant changes in condylar area, perimeter or height values between RX1 and RX2.

Conclusions

This study has demonstrated that (1) the height of the condyle can be rapidly and reliably assessed using a specific computer system directly on digital panoramic radiographs; (2) although less reliable, area and perimeter can also be acceptably evaluated; and (3) this method has the potential for being routinely used to monitor changes in clinical follow-up as well as for research purposes.     

Cemento-osseous dysplasia,a radiological mimic of periapical dental abscess

In the imaging evaluation of Emergency Department patients presenting with facial pain, there is a condition that can mimic the radiographic appearance of a periapical dental abscess. This condition, cemento-osseous dysplasia, may appear similar on dental X-rays, panoramic radiographs, and computed tomography examinations to and must be distinguished from the more common periapical abscess in order to avoid inappropriate intervention. This review highlights the easy confusion of these two entities based on radiographic appearance and the clinical implications of such a mistake and suggests some approaches to avoid this error.     

Comparison between panoramic and periapical radiography in the diagnosis of periodontal bone loss

Panoramic and periapical radiography was performed on 100 patients. Five observers each registered the scores for marginal bone level, presence of bone defects and furcation involvement in the radiographs of 20 patients and the results were compared. The overall concordance in scoring the marginal bone level was high when panoramic and periapical radiography was compared. In the upper arch, 66% of the sites showed concordant scores, 31% deviated by one and 3% by two score-points. In the lower arch, 74% of sites had concordant scores, 25% deviated by one and 1% by two score-points. The panoramic radiographs more often indicated a more severe bone loss than the periapical radiographs. The concordance was related to the degree of bone loss. In sites with no bone loss the concordance was high whereas it was lower in those with severe bone loss. The concordance of the two radiographic methods for the mandibular canine, premolars and first molar was equally as high as the intra-observer overall agreement, but lowest for the mandibular central incisors and the maxillary molars. Bone defects were more easily identified by periapical radiography.     

Narrowing of the inferior dental canal in relation to the lower third molars

OBJECTIVES: To assess narrowing of the inferior dental canal in the lower third molar regions using computed tomography (CT) and to determine the value of radiographic markers on rotational panoramic radiographs in assessing the true relationships of the inferior dental canal. METHODS: Patients referred for CT assessment of impacted lower third molars were used in this study. The lower third molars were assessed using CT to determine the position and morphology of the inferior dental canal relative to the roots and the cortical plates. The radiographic markers on rotational panoramic radiographs were correlated with the CT findings when rotational panoramic radiographs were available. RESULTS: The patients referred had 202 lower third molars. Inferior positioning of the inferior dental canal was the most common location on CT. Narrowing of the inferior dental canal was found in relation to the lower third molars in 66.8% of cases. The chance of narrowing of the inferior dental canal as shown using CT increased when at least one of the radiographic markers, superimposition, narrowing, deviation or reduction in density was present on the rotational panoramic radiograph. Deviation of the inferior dental canal on rotational panoramic radiographs was found to be the most significant predictor of narrowing of the inferior dental canal and a close relationship to the roots, as shown in CT. CONCLUSIONS: Narrowing of the inferior dental canal is a common finding when impacted lower third molars are assessed using CT. On rotational panoramic radiographs deviation of the inferior dental canal is the best predictor of narrowing of the inferior dental canal and a close relationship to the roots.     

Development of formulae for dental age estimation using digital radiographs in the Mongolian population

This study aimed to examine the applicability of the pulp/tooth ratio (PTR) method for age estimation in Mongolian populations using panoramic radiographs and derive new regression formulae. Moreover, we aimed to assess the accuracy of these formulae in other subjects from the Mongolian population and compare them with the other formulae derived from different Asian populations.The total sample size of the study was 381. The formulae were derived from the examination of panoramic radiographs of 271 individuals aged 15–62 years. Following Cameriere’s method, PTR was calculated for the upper and lower canine teeth. Linear regression analyses were performed between the actual age and that obtained from upper-lower canine PTR and established formulae for age estimation. To verify the formulae, two types of test samples were collected: 73 panoramic radiographs and 37 periapical radiographs. The estimated age was calculated using our new formulae and three other formulae derived from Asian populations.The correlation coefficient between the actual age and that obtained by PTR was significantly negative for both canines. According to our new regression formulae, the differences between the estimated age and actual age showed a bell-shaped curve distribution in both test groups. While using the other formulae derived from the Asian population, the distribution patterns obtained were significantly different in the Mongolian population.This study was the first to examine the relationship between actual age and PTR in Mongolian population, and these results advance the field of forensic science in Mongolia.     

Fractal analysis of the trabecular bone pattern in the presence/absence of metal artifact–producing objects: Comparison of cone-beam computed tomography with panoramic and periapical radiography

Objectives:The effect of metallic objects on the fractal dimension (FD), bone area fraction (BAF) and gray scale values (GSVs) of cone-beam CT (CBCT) images was assessed. Also, FD, BAF and GSV were compared among CBCT, digital periapical and panoramic radiographies.Methods:Digital periapical and panoramic radiographs were acquired from six blocks of bovine rib. Additionally, different arrangements of titanium implants and intracanal metallic posts were created in the bone blocks and CBCT scans were taken from the different implant-root arrangements. The three radiographical modalities were compared by analysis of variance. Pairwise comparisons between the modalities were performed by the Tukey test (significance level set at 0.05).Results:Different root-implant arrangements in the CBCT images revealed no significant differences in the FD (p = 0.920), BAF and GSV values (p = 0.623). FD differed significantly among the three modalities (p < 0.001). Significant differences were found between CBCT and each of the periapical and panoramic techniques (p < 0.001), while no remarkable differences were observed in the FD of the periapical and panoramic images (p = 0.294). BAF and GSV showed significantly different results among the three radiographical techniques (p < 0.001). The difference was remarkable between CBCT and periapical (p < 0.001), CBCT and panoramic (p < 0.001) and periapical and panoramic (p = 0.008).Conclusion:Presence of titanium implants and intracanal posts does not produce different results in the fractal analysis (FA) of the CBCT images. The trabecular bone pattern is best assessed by FA of the periapical radiographs followed by the panoramic and CBCT techniques, respectively.     

Pneumatization of the sphenoid sinus

This paper describes a case of pneumatization of the sphenoid sinus in the pterygoid process and greater wing of the sphenoid bone, observed on a panoramic radiograph. Conventional radiographs and computerized tomography in axial and coronal sections confirmed the presence of the pneumatization of these structures.     

A new method for the radiological investigation of residual ridge resorption in the maxilla

OBJECTIVES: To develop a new method for assessing residual ridge resorption in the edentulous maxilla. METHODS: Defined experimental and reference areas in the maxilla were drawn on transparent film laid over a panoramic radiograph and digitized. Bone areas were measured with an integrated planimetry program and expressed as a ratio R. The effect of positioning errors on reliability of the method was investigated on dry skulls. The correlation between the change in ratio and actual bone loss was examined by progressively reducing the height of an artificial residual ridge on one skull. RESULTS: The coefficient of variation for the absolute ratio in different head positions was < 0.05 and its correlation coefficient of the change in R and the degree of resorption was r2 > or = 98.3%, P = 0.0001. CONCLUSIONS: Comparison of the experimental area with the reference area on serial panoramic radiographs appears suitable for the assessment of residual resorption in the maxilla.