Measurements of tooth length in panoramic radiographs. 2: Observer performance.

Observer performance in tooth-length measurements in panoramic radiography has been examined. Sixty-four teeth, evenly distributed between maxillary first molars, second premolars and mandibular first and second premolars, were fixed in plastic moulds. Each cast was radiographed with an Orthopantomograph, twice with steel balls indicating the cusps and apices of the teeth and once without them. One observer measured the radiographic tooth length twice in both radiographs with indicators in order to estimate the true radiographic tooth length and the repositioning error, and twice in the radiographs without indicators. Seven other observers measured the tooth length on the radiographs without indicators, twice applying their own criteria and twice using defined criteria. The accuracy of the tooth-length measurements was calculated by comparing the true radiographic tooth length with the measurements of the seven observers. The intra-observer variation was defined as the difference between two measurements on the same radiograph. The accuracy and the precision of the tooth-length measurements were highly influenced by the observer performance. The mean radiographic tooth length of the seven observers was closer to the true radiographic tooth length when the observers applied the defined criteria. The inter- and intra-observer variation was higher for the measurements of the maxillary teeth (0.3-1.9 mm) compared with the mandibular teeth (0.3-0.9 mm) for most observers. The highest intra-observer variation was found for the palatal root of the maxillary first molar. The intra-observer variation of four observers decreased somewhat when the defined criteria were used; for the other three observers, however, the variation increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

CBC T 测量上颌后牙根尖与上颌窦底距离的应用价值

目的：通过CBC T资料分析吉林地区正常人群上颌后牙根尖与上颌窦底的距离,为上颌磨牙区的牙种植术和疾病诊断以及治疗计划等临床口腔外科提供解剖学基础。方法从吉林大学口腔医院放射科留存的CBC T 资料中,选择上颌后牙健康,没有经过外科手术和正畸等处理的CBC T资料27例（其中男13例,女14例）,利用CBC T 配套软件进行三维重建,并用软件内置测量工具逐一测量上颌第二前磨牙、第一磨牙和第二磨牙根尖与上颌窦底的距离。结果上颌后牙各个牙根与上颌窦底距离在左右两侧和男女之间无差异（ P ＞0．05）。27名试验人员（54侧）CBC T 中,上颌第二前磨牙牙根、第一磨牙的近中根、腭根、远中根、第二磨牙的近中根、腭根、远中根的根尖与上颌窦底的距离分别为：（4.13±3．71）m m、（3．12±3．76）m m、（3．50±3．58）m m、（2．62±3．32）m m、（1．81±2．55）m m、（3．14±3．08）m m、（2．67±3．27）m m。结论上颌第二磨牙近中根根尖距离上颌窦底最近,上颌第二前磨牙根尖距离上颌窦底最远（ P＜0．05）。     

Prediction of premolar tooth lengths based on their panoramic radiographic lengths

OBJECTIVE: Establishing a linear regression model for the determination of first premolar lengths based on panoramic radiographs. MATERIALS AND METHODS: The real lengths of 112 first premolars extracted for orthodontic reasons were measured and compared with their panoramic lengths. The teeth were divided into four groups according to their intraoral quadrant locations (T14, T24, T34, T44) and regression analysis was conducted for each group. RESULTS: A linear regression model for the prediction of tooth length (mm) based on the panoramic length was established (P < 0.0001): For group T14 the predicted length = (panoramic length x 0.698) + 2.61. For group T24 the predicted length = (panoramic length x 0.5056) + 7.844. For group T34 the predicted length = (panoramic length x 0.5075) + 9.282. For group T44 the predicted length = (panoramic length x 0.436) + 11.298. CONCLUSION: Prediction of all first premolar lengths using their panoramic images is both feasible and reliable.     

Comparison of racemization rates between vital and endodontically treated teeth for age estimation

Amino acid racemization of dentin (AAR) is among the most precise methods for age estimation in unidentified adult cadavers. Although vital teeth are generally used for this technique, cases often have endodontically treated (Endo) teeth only. Therefore, the aim of this preliminary pilot study was to determine the applicability of Endo teeth by comparing AAR rates between vital and Endo teeth. Thirty-six dentin samples from vital teeth and 18 dentin samples from Endo teeth were analyzed, including the maxillary first premolar, maxillary second molar, and mandibular second premolar. Standard calibration curves for the mandibular second premolar and maxillary second molar were compared among vital teeth, Endo teeth, and mixed vital/Endo teeth. Discrepancies between estimated and actual ages were assessed by analyzing the AAR rates for the maxillary first premolar between vital and Endo teeth. The AAR rates for Endo teeth were higher than those for vital teeth in both the mandibular second premolar and maxillary second molar, and the correlation of the standard calibration curve for vital teeth only was highest (r = 0.982836; r = 0.92011467), followed by mixed (r = 0.949579; r = 0.76158) and Endo teeth only (r = 0.896082; r = 0.744991). In the maxillary first premolar, discrepancies were more than 10 years for all 5 Endo teeth, based on the standard calibration curve of vital teeth. The present study suggests that the AAR rates for Endo teeth might be affected by variation in dentin structure between vital and Endo teeth.     

Accuracy of vertical height measurements on direct digital panoramic radiographs using posterior mandibular implants and metal balls as reference objects

Objectives:

Conventional panoramic radiography, a widely used radiographic examination tool in implant treatment planning, allows evaluation of the available bone height before inserting posterior mandibular implants. Image distortion and vertical magnification due to projection geometry is well described for rotational panoramic radiographs. To assess the accuracy of vertical height measurements on direct digital panoramic radiographs, implants and metal balls positioned in the posterior mandible were used as radio-opaque reference objects. The reproducibility of the measuring method was assessed by the inter- and intraobserver agreements.

Methods:

Direct digital panoramic radiographs, performed using a Kodak 8000C (Eastman Kodak Company, Rochester, NY), of 17 partially edentulous patients (10 females, 7 males, mean age 65 years) were selected from an X-ray database gathered during routine clinical evaluation of implant sites. Proprietary software and a mouse-driven calliper were used to measure the radiological length of 25 implants and 18 metal reference balls, positioned in mandibular posterior segments. The distortion ratio (DR) was calculated by dividing the radiological implant length by the implant''s real length and the radiological ball height by the ball''s real height.

Results:

Mean vertical DR was 0.99 for implants and 0.97 for balls, and was unrelated to mandibular sites, side, age, gender or observer. Inter- and intraobserver agreements were acceptable for both reference objects.

Conclusions:

Vertical measurements had acceptable accuracy and reproducibility when a software-based calibrated measurement tool was used, confirming that digital panoramic radiography can be reliably utilized to determine the pre-operative implant length in premolar and molar mandibular segments.     

Radiographic alveolar bone loss in untreated Taiwan Chinese subjects with adult periodontitis measured by the digital scanning radiographic image analysis method

OBJECTIVES: To determine differences in radiographic alveolar bone loss (RABL) by age group, gender and tooth type in subjects with adult periodontitis using the digital scanning radiographic image analysis (DSRIA) method. METHODS: A total of 4262 teeth were examined for RABL in 178 individuals (96 males and 82 females). Mesial and distal sites were determined by the DSRIA method following scanning of periapical radiographs and using the Microstation 95 image software. RESULTS: Linear assessment of RABL using DSRIA revealed the following results. Mean bone loss of maxillary and mandibular anterior teeth was significantly higher (P<0.001 and P<0.01, respectively) in males compared with females using a two-sample t-test. The highest values of mean RABL occurred most commonly in the maxillary first molars (53.8% and 51.4% for females and males, respectively) and the mandibular central incisors (50.4% and 41.5% for males and females, respectively). Mean RABL was greater in males than in females for both the mandibular and maxillary arches, with the exception of molar sites. CONCLUSIONS: Maxillary first molars and mandibular incisors are the highest risk sites. Moreover, greater loss occurs at the molar site in females compared with males for untreated periodontitis in Taiwan Chinese people.     

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.     

Pre-operative radiographic evaluation of lower third molars with computed tomography

OBJECTIVES: To report radiographic findings of examinations with computed tomography (CT) of impacted lower third molars with an intimate relation to the mandibular canal and to investigate how findings of a dark band across the roots of the lower third molar on panoramic views correspond to the CT findings. METHODS: CT images of 90 lower third molars (64 patients, mean age 34.6 years) in which plain radiography was insufficient to allow determination of the precise anatomical relations were reviewed retrospectively. Panoramic views of 88 teeth existed; these images were interpreted independent of the CT examinations with respect to presence of a dark band across the roots. RESULTS: In 31% of the CT images, the course of the mandibular canal was buccal, in 33% lingual, in 26% inferior, and in 10% inter-radicular. The tooth was in contact with the mandibular canal in 94% and with the lingual cortex in 86%. In 23%, grooving of the root by the canal was judged to be present. In 63% of the cases where a dark band across the roots was observed on panoramic radiographs, CT revealed grooving of the root. CONCLUSIONS: Pre-operative CT of lower third molars is motivated in selected cases when plain radiography is inconclusive. The finding of a dark band across the roots on panoramic radiographs is an indicator of grooving of the tooth by the canal and justifies a pre-operative CT examination. The absence of dark bands on panoramic views does not exclude grooving of the roots.     

Radiographic examination of dentigerous cysts in the transitional dentition

OBJECTIVES: To examine radiographically the relationship between the deciduous tooth and dentigerous cyst of the permanent successor during the transitional dentition. METHODS: From a retrospective review of all patients who visited our institution from April 1988 to August 2001, 70 patients under 16 years of age who had histologically confirmed dentigerous cysts that had developed from the central incisor to the second premolar were identified. These 70 patients were investigated using panoramic and periapical radiographs. RESULTS: In most cases (54 cases; 77.1%) the cyst was in the premolar region. Of the 54 premolars with dentigerous cysts, the overlying deciduous tooth had already been lost in 7 cases. Of the 47 remaining premolars with associated deciduous tooth, 35 (74.5%) had bone resorption of the periapical or bifurcation region, or irregular resorption of the associated deciduous tooth. Of the remaining 12 deciduous teeth with no periapical lesions, 9 had been treated with root canal therapy. Thus, 44 of these 47 cases (93.6%) had the possibility of inflammation at the deciduous tooth associated with the dentigerous cyst. Evidence from one case in the present study suggesting the process by which cyst development occurs is also given. CONCLUSION: Inflammatory change at the apex of the deciduous tooth may bring on a dentigerous cyst of the permanent successor.     

Assessment of bone mineral density in the jaws and its relationship to radiomorphometric indices

Objectives

The aim of this study was to evaluate maxillary, mandibular and femoral neck bone mineral density using dual energy X-ray absorptiometry (DXA) and to determine any correlation between the bone mineral density of the jaws and panoramic radiomorphometric indices.

Methods

49 edentulous patients (18 males and 31 females) aged between 41 and 78 years (mean age 60.2 ± 11.04) were examined by panoramic radiography. Bone mineral density (BMD) of the jaws and femoral neck was measured with a DXA; bone mineral density was calculated at the anterior, premolar and molar regions of the maxilla and mandible.

Results

The mean maxillary molar BMD (0.45 g cm⁻²) was significantly greater than the maxillary anterior and premolar BMD (0.31 g cm⁻², P < 0.05). Furthermore, the mean mandibular anterior and premolar BMD (1.39 g cm⁻² and 1.28 g cm⁻², respectively) was significantly greater than the mean mandibular molar BMD (1.09 g cm⁻², P < 0.01). Although BMD in the maxillary anterior and premolar regions were correlated, BMD in all the mandibular regions were highly correlated. Maxillary and mandibular BMD were not correlated with femoral BMD. In addition, mandibular cortical index (MCI) classification, mental index (MI) or panoramic mandibular index (PMI) values were not significantly correlated with the maxillary and mandibular BMDs (P > 0.05).

Conclusions

The BMD in this study was highest in the mandibular anterior region and lowest in the maxillary anterior and premolar regions. The BMD of the jaws was not correlated with either femoral BMD or panoramic radiomorphometric indices.     

Radiographic study of the mental foramen in a selected Saudi population

OBJECTIVES: To determine the most common position of the mental foramen in a selected Saudi population and to compare the results with those reported for other populations. METHODS: Four hundred and fourteen panoramic radiographs of a Saudi population from four different dental centres were studied. RESULTS: The commonest position of the mental foramen was in line with the longitudinal axis of the second premolar (45.3%) followed closely by location between the first and second premolars (42.7%). The mental foramen was symmetrical in 80% of patients. CONCLUSION: Clinicians should expect to find the position of the mental foramen to be symmetrical and in line with the second premolar teeth.     

Human dental age estimation combining third molar(s) development and tooth morphological age predictors

In the subadult age group, third molar development, as well as age-related morphological tooth information can be observed on panoramic radiographs. The aim of present study was to combine, in subadults, panoramic radiographic data based on developmental stages of third molar(s) and morphological measurements from permanent teeth, in order to evaluate its added age-predicting performances. In the age range between 15 and 23?years, 25 gender-specific radiographs were collected within each age category of 1?year. Third molar development was classified and registered according the 10-point staging and scoring technique proposed by Gleiser and Hunt (1955), modified by K?hler (1994). The Kvaal (1995) measuring technique was applied on the indicated teeth from the individuals’ left side. Linear regression models with age as response and third molar-scored stages as explanatory variables were developed, and morphological measurements from permanent teeth were added. From the models, determination coefficients (R ²) and root-mean-square errors (RMSE) were calculated. Maximal-added age information was reported as a 6?% R2 increase and a 0.10-year decrease of RMSE. Forensic dental age estimations on panoramic radiographic data in the subadult group (15–23?year) should only be based on third molar development.     

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.     

Accuracy of measurements of mandibular anatomy and prediction of asymmetry in panoramic radiographic images

OBJECTIVES: Measurements of ideally positioned and systematically mis-positioned skulls were used to evaluate errors in linear measurements and symmetry ratios made with panoramic X-ray images. METHODS: Digital panoramic images of 30 skulls placed in ideal, shifted and rotated positions, were assessed by measuring distances between anatomic points and fiducial references. Differences between photographic measurements (control) and radiographic measurements were compared. Horizontal measurements included a 20 mm wire and the distance from gonion to mental foramen (G-MF). Vertical distances measured included a 40 mm wire, condyle to sigmoid notch length, and condyle to gonion (posterior mandibular height or PMH). A relative symmetry ratio comparing the difference between right and left PMH was also calculated. Distances measured in panoramic images were corrected using the left vertical wire distance or the panoramic unit's stated magnification factor (1.25x). RESULTS: Greatest differences were noted for horizontal measurements and shifted skull positions. Use of an arbitrary magnification correction was consistently less accurate than use of an internal calibration and resulted in general underestimation of actual dimensions. Measures of PMH varied significantly from expected values for each of the three skull positions (P<0.005). Panoramic accuracy for detecting asymmetry was 67% for ideal, 70% for rotated, and 47% for shifted skull positions when an internal reference was used. CONCLUSIONS: Panoramic radiographs should be used with caution in making absolute measurements or relative comparisons. Even when internal fiducial calibration for image distortion of anatomy is used, measurements such as those assessing posterior mandibular facial symmetry may be unreliable.     

Benign cementoblastoma in a primary lower molar, a rarity

An asymptomatic radiopacity surrounded by a radiolucent line was observed from a panoramic radiograph of an 11-year-old girl. The lesion was associated with the mesial root of the lower right second primary molar. The radiographic appearance of the lesion suggested a benign cementoblastoma. Histological diagnosis after surgical excision of the tumour and extraction of the tooth confirmed the radiographic diagnosis. Benign cementoblastomas associated with primary teeth are extremely rare lesions. To our knowledge, only eight cases have been reported in the literature.     

Magnification rate of digital panoramic radiographs and its effectiveness for pre-operative assessment of dental implants

Objectives

The purpose of this study was to determine the accuracy and effectiveness of digital panoramic radiographs for pre-operative assessment of dental implants.

Methods

We selected 86 patients (221 implants) and calculated the length of the planned implant based on the distance between a selection of critical anatomical structures and the alveolar crest using the scaling tools provided in the digital panoramic system. We analysed the magnification rate and the difference between the actual inserted implant length and planned implant length according to the location of the implant placement and the clarity of anatomical structures seen in the panoramic radiographs.

Results

There was no significant difference between the planned implant length and actual inserted implant length (P > 0.05). The magnification rate of the width and length of the inserted implants, seen in the digital panoramic radiographs, was 127.28 ± 13.47% and 128.22 ± 4.17%, respectively. The magnification rate of the implant width was largest in the mandibular anterior part and there was a significant difference in the magnification rate of the length of implants between the maxilla and the mandible (P < 0.05). When the clarity of anatomical structures seen in the panoramic radiographs is low, the magnification rate of the width of the inserted implants is significantly higher (P < 0.05), but there is no significant difference between the planned implant length and actual inserted implant length according to the clarity of anatomical structures (P < 0.05).

Conclusions

Digital panoramic radiography can be considered a simple, readily available and considerably accurate pre-operative assessment tool in the vertical dimension for dental implant therapy.     

Usefulness of cone beam computed tomography for odontogenic myxoma

A case of odontogenic myxoma is reported as showing a cyst-like pattern with a partially thick but vague and unclear radiopaque border between the left mandibular second premolar and first molar on rotational panoramic radiography. Internal structure of the lesion displayed radiolucency with a sparse and coarse trabecular pattern. No expansion of bucco-lingual cortical bone was apparent. The radiographic pattern of odontogenic myxoma did not resemble a tennis racket-like or straight, curved and coarse septal appearance on panoramic radiography, but characteristic findings were noted on cone beam CT. Cone beam CT may prove extremely useful in clarifying detailed internal structure and the state of margins.     

Correlation of panoramic radiography and cone beam CT findings in the assessment of the relationship between impacted mandibular third molars and the mandibular canal

Objectives

The aim of this study was to assess the reliability of four panoramic radiographic findings, both individually and in association, in predicting the absence of corticalization between the mandibular canal and the third molar on cone beam CT (CBCT) images.

Methods

The sample consisted of 72 individuals (142 mandibular third molars) who underwent pre-operative radiographic evaluation before extraction of impacted mandibular third molars. On panoramic radiographs, the most common signs of corticalization (darkening of roots, diversion of mandibular canal, narrowing of mandibular canal and interruption of white line) and the presence or absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were evaluated.

Results

Darkening of roots and interruption of white line associated with the absence of corticalization between the mandibular third molar and the mandibular canal on CBCT images were statistically significant, both as isolated findings (p = 0.0001 and p = 0.0006, respectively) and in association (p = 0.002). No statistically significant association was observed for the other panoramic radiographic findings, either individually or in association (p > 0.05).

Conclusion

Darkening of roots and interruption of white line observed on panoramic radiographs, both as isolated findings and in association, were effective in determining the risk relationship between the tooth roots and the mandibular canal, requiring three-dimensional evaluation of the case.     

An assessment of the aggressive potential of radiolucencies related to the mandibular molar teeth

AIM: The purpose of this study was to outline the radiographic appearance of radiolucent lesions related to the molar teeth and to determine which features indicate aggressive lesions. PATIENTS AND METHODS: Panoramic radiographs were reviewed in 66 patients with radiolucencies related to the molar teeth. The radiographic appearances of the lesions were assessed with regard to location and size, and the relationship to the molar teeth. Radiographic evidence of aggression was assessed and pathology reviewed. RESULTS: Nineteen patients had aggressive and 47 had non-aggressive radiolucent lesions. The aggressive lesions included keratocysts, unicystic ameloblastoma, adenoid cystic carcinoma, giant cell granuloma, myxofibroma, chondroblastic osteosarcoma, mestastases and squamous cell carcinoma of the tongue invading the mandible. CONCLUSION: The differential diagnosis of radiolucent lesions in the mandible can be difficult using panoramic radiographs alone. Helpful features in determining aggression were older patients, larger lesions, Lodwick type IC tumour border, condition of the mandibular cortex, movement of adjacent teeth and the relationship of the inferior alveolar canal.