Frab Norberto Bóscolo

THE RELATIONSHIP BETWEEN TEMPOROMANDIBULAR DYSFUNCTION AND HEAD AND CERVICAL POSTURE

Objective: This study aimed to evaluate the possibility of any correlation between disc displacement and parameters used for evaluation of skull positioning in relation to the cervical spine: craniocervical angle, suboccipital space between C0-C1, cervical curvature and position of the hyoid bone in individuals with and without symptoms of temporomandibular dysfunction. Material and Methods: The patients were evaluated following the guidelines set forth by RDC/TMD. Evaluation was performed by magnetic resonance imaging for establishment of disc positioning in the temporomandibular joints (TMJs) of 30 volunteer patients without temporomandibular dysfunction symptoms and 30 patients with symptoms. Evaluation of skull positioning in relation to the cervical spine was performed on lateral cephalograms achieved with the individual in natural head position. Data were submitted to statistical analysis by Fishers exact test at 5% significance level. To measure the degree of reproducibility/agreements between surveys, the kappa (K) statistics was used. Results: Significant differences were observed between C0-C1 measurement for both symptomatic (p=0.04) and asymptomatic (p=0.02). No statistical differences were observed regarding craniocervical angle, C1-C2 and hyoid bone position in relation to the TMJs with and without disc displacement. Although statistically significant difference was found in the C0-C1 space, no association between these and internal temporomandibular joint disorder can be considered. Conclusion: Based on the results observed in this study, no direct relationship could be determined between the presence of disc displacement and the variables assessed.

Bone density: comparative evaluation of Hounsfield units in multislice and cone-beam computed tomography

The aim of this study was to evaluate the validity of the bone density value of potential implant sites in HU obtained by a specific cone-beam computed tomography (CBCT) device. In this study, the HU values obtained using a MSCT scanner were used as the gold standard. Twenty mandibles (40 potential implant sites) were scanned using an MSCT scanner (Somatom Sensation 40) and a CBCT scanner (i-CAT). The MSCT images were evaluated using the Syngo CT Workplace software and the CBCT images, using the XoranCat software. The images were evaluated twice by three oral radiologists, at 60 day intervals. The trabecular bone density of the same area was evaluated on both images. Intraclass coefficients (ICC) were calculated to examine the agreement between the examiners and between the two periods of evaluation. The bone density and area of the ROI were compared by the Student t test and Bland-Altman analysis. ICCs were excellent. The mean HU value obtained using CBCT (418.06) was higher than that obtained using MSCT (313.13), with a statistically significant difference (p < 0.0001). In addition, Bland-Altman analysis showed that the HU measures were not equivalent. In conclusion, the bone density in HU with CBCT images obtained using the device studied proved unreliable, since it was higher than that obtained using MSCT.

Assessment of enamel demineralization using conventional, digital, and digitized radiography

This experimental research aimed at evaluating the accuracy of enamel demineralization detection using conventional, digital, and digitized radiographs, as well as to compare radiographs and logarithmically contrast-enhanced subtraction images. Enamel subsurface demineralization was induced on one of the approximal surfaces of 49 sound third molars. Standardized radiographs of the teeth were taken prior to and after the demineralization phase with three digital systems--CygnusRay MPS, DenOptix and DIGORA--and InSight film. Three radiologists interpreted the pairs of conventional, digital, and digitized radiographs in two different occasions. Logarithmically contrast-enhanced subtraction images were examined by a fourth radiologist only once. Radiographic diagnosis was validated by cross-sectional microhardness profiling in the test areas of the approximal surfaces. Accuracy was estimated by Receiver Operating Characteristic (ROC) analysis. Chi-square test, at a significance level of 5%, was used to compare the areas under the ROC curves (A(z)) calculated for the different imaging modalities. Concerning the radiographs, the DenOptix system (A(z) = 0.91) and conventional radiographs (A(z) = 0.90) presented the highest accuracy values compared with the other three radiographic modalities. However, logarithmically contrast-enhanced subtraction images (A(z) = 0.98) were significantly more accurate than conventional, digital, and digitized radiographs (p = 0.0000). It can be concluded that the DenOptix system and conventional radiographs provide better performance for diagnosing enamel subsurface demineralization. Logarithmic subtraction significantly improves radiographic detection.

Image quality in digital radiographic systems

The aim of the present study was to evaluate the image quality of four direct digital radiographic systems. Radiographs were made of the maxillary central incisor and mandibular left molar regions of a dry skull, and an aluminum step-wedge. The X-ray generator operated at 10 mA. 60 and 70 kVp, and images were acquired with 3, 5, 8, 12, 24 and 48 exposure pulses. Six well-trained observers classified the images by means of scores from 1 to 3. Collected data were submitted to nonparametric statistical analysis using Fishers exact test. Statistical analysis showed significant differences (p < 0.01) in image quality with the four systems. Based on the results, it was possible to conclude that: 1) all of the digital systems presented good performance in producing acceptable images for diagnosis, if the exposures of the step-wedge and the maxillary central incisor region were made at 5 pulses, as well as at 8 pulses for the mandibular left molar region, selecting 60 or 70kVp; 2) higher percentages of acceptable images were obtained with the administration of lower radiation doses in CCD-sensors (charge-coupled device); 3) the Storage Phosphor systems produced acceptable images at a large range of exposure settings, that included low, intermediate and high radiation doses.

Artefact expression associated with several cone‐beam computed tomographic machines when imaging root filled teeth

AIM To evaluate the characteristic artefact patterns associated with teeth root filled with Gutta-percha when scanned with four cone-beam CT devices. METHODOLOGY Whilst using soft tissue simulation, ten root filled human premolars were placed in empty sockets in a dry human skull. Subsequently, the skull was scanned using 3D Accuitomo 170(®) , WhiteFox(®) , Cranex 3D(®) and Scanora 3D(®) following clinical protocols with the highest resolution and artefact reduction. After proper image registration in OnDemand3D(®) software (Cybermed, Seoul, Korea), each image slice was evaluated by three trained and calibrated dentomaxillofacial radiologists, which scored absence (0) and presence (1) of cupping artefact, hypodense halos and streak artefacts. Kappa test was performed for intra- and interobserver agreement. RESULTS A moderate to perfect agreement for each observer (intra-observer κ = 0.5-1.0) was found. Agreement between the different observers was moderate to almost perfect for the different artefact patterns (interobserver κ = 0.55-0.9). Cupping artefact was the most prevalent (70%), followed by a hypodense halo (35%) and streak artefacts (16%). The Chi-squared test revealed significantly more streaks in axial slices (P < 0.0001), with some CBCT systems yielding significantly inferior results to others (P < 0.05). The dedicated EndoMode and artefact reduction did not improve the result significantly. CONCLUSIONS The variation of artefact expression was significantly different amongst CBCT machines for root filled teeth. Continuous efforts are needed to improve CBCT reconstruction algorithms, with a specific focus on reducing artefacts induced by dense dental materials, whilst striving for enhanced image quality at low-radiation doses.

Comparison of TW2 and TW3 skeletal age differences in a Brazilian population

Objective: The aim of this study was to determine the differences between the skeletal ages estimated by TW2 and TW3 methods through their RUS and Carpal systems. Material and Methods: A sample of two hundred and forty hand and wrist radiographs of male and female Brazilian children aged 84-199 months was evaluated by five observers. The Dunnet test was performed for statistical analysis. Results: Results showed higher skeletal ages estimated by TW2RUS than TW3RUS and Carpal for both genders. For girls a statistically significant difference (p<0.05) was observed between TW2RUS and TW3RUS over the entire age range. For boys this difference was observed from 108 months onwards. In general RUS skeletal ages were higher than the chronological age and Carpal skeletal ages for both genders. The overestimation of chronological age was smaller for TW3RUS than for TW2RUS, and this last system showed a statistically significant difference regarding chronological age over the entire age range for girls, whereas for boys this difference was seen from 132 months onwards. For girls TW3 RUS and Carpal showed a significant difference regarding chronological age in the oldest age groups; in boys TW3RUS did not show a significant difference regarding chronological age. For Carpal, these results were more variable. Conclusion: It seems reasonable to recommend the use of the TW3 system for the studied Brazilian population.

Nasolabial cyst: presentation of a clinical case with CT and MR images

The nasolabial cyst is an uncommon non-odontogenic cyst that develops in the lower region of the nasal ala; its pathogenesis is uncertain. This lesion grows slowly and measures between 1.5 and 3 cm; it is characterized clinically by a floating tumefaction in the nasolabial sulcus, which elevates the upper lip. The diagnosis is based on the clinical findings and, if necessary, image exams. This paper reports a case of a white 48-year-old Brazilian female patient that presented a firm tumor in the left ala of the nose; the clinical features suggested a nasolabial cyst. CT scans revealed an expanding tumor with soft tissue density located in the left ala of the nose. It measured 1.2 cm in diameter and had a clear and well-defined outline; its homogeneous density was about 50 HU. MR images revealed a circular lesion located in soft tissue; T1 and T2 weighted signals were hyperintense, as were images after fat suppression. The diagnosis was a nasolabial cyst, which was confirmed by histopathology after surgery.

In vitro induction of enamel subsurface demineralization for evaluation of diagnostic imaging methods

The aim of this study was to investigate a model of inducing enamel subsurface demineralization for evaluating diagnostic imaging methods. Fifty sound teeth had their crowns coated with acid-resistant varnish, leaving a 7 mm2 circular window of exposed enamel in one of the proximal surfaces. The specimens were assigned to 5 groups (4 experimental and the control) and were kept immersed in a buffer solution at pH 4.8, 50% saturated in relation to enamel, for 60, 75, 90 and 120 days, or were not exposed to the solution. Digital radiographs were taken, prior to and after each immersion period, and interpreted by a radiologist. For validation, the enamel was submitted to microhardness profiling. In addition, the solutions were analyzed for phosphorus (Pi) and calcium (Ca) concentrations. Microhardness data were evaluated using two-way ANOVA (p<0.05) and Tukeys test. Pi and Ca concentrations were compared using one-way ANOVA (α = 0.05). The performance of radiography was assessed by ROC analysis. The microhardness values for the control group ranged from 405 to 432 KHN. Of the 4 experimental groups, the 60-day group demonstrated the highest values (179-379 KHN) and the 120-day group, the lowest values (103-277 KHN). The lowest total concentrations of Pi and Ca (1.74 mM and 2.63 mM, respectively) were found in the solutions of the 60- day group, indicating the lowest rate of mineral loss, however, there was no significant difference among the other experimental groups. The performance for detecting images consistent with caries lesions was high (Az = 0.89). Therefore, this in vitro model of inducing demineralization may be considered suitable for research intended to evaluate imaging methods for the diagnosis of proximal caries lesions.

Diagnosis of invasive cervical resorption by using cone beam computed tomography: report of two cases

A radiographic interpretation is essential to the diagnosis of invasive cervical resorption (ICR) and the difficulty in distinguishing this lesion from internal root resorption has been highlighted in the literature. This paper reports the use of cone beam computed tomography (CBCT) in the diagnosis of ICR. The cases reports describe how CBCT can be used to make a differential diagnosis and also show that the use of this technology can provide relevant information on the location and nature of root resorption, which conventional radiographs cannot. As a result, the root canal treatment was not initially considered. The patients will be monitored and will undergo a scan after a short period of time to detect any small changes. It was observed that both cases benefited from CBCT in the diagnosis of ICR, because this imaging modality determined the real extent of resorption and possible points of communication with the periodontal space.

Effect of sodium selenite on bone repair in tibiae of irradiated rats

This study evaluated the radioprotective effect of sodium selenite on the bone repair process in tibiae of female rats. For such purpose, 100 female Wistar rats (Rattus norvegicus, albinus) were randomly assigned to 4 groups (n=25), according to the treatment received: administration of distilled water (control); administration of sodium selenite; gamma radiation; and administration of sodium selenite plus gamma radiation. A bone defect was prepared on both tibiae of all animals. Three days after surgery, the gamma radiation and selenium/gamma radiation groups received 8 Gy gamma rays on the lower limbs. Five animals per group were sacrificed 7, 14, 21, 28 days after surgery for evaluation of the repair process by bone volumetric density analysis. The 5 animals remaining in each group were sacrificed 45 days postoperatively for examination of the mature bone by scanning electron microscopy. Based on all analyzed parameters, the results of the present study suggest that sodium selenite exerted a radioprotective effect in the bone repair of tibia of irradiated rats.