Efficacy of lead foil for reducing doses in the head and neck: a simulation study using digital intraoral systems.

OBJECTIVES: To assess the efficacy of lead foils in reducing the radiation dose received by different anatomical sites of the head and neck during periapical intraoral examinations performed with digital systems. METHODS: Images were acquired through four different manners: phosphor plate (PSP; VistaScan(®) system; Dürr Dental GmbH, Bissingen, Germany) alone, PSP plus lead foil, complementary metal oxide semiconductor (CMOS; DIGORA(®) Toto, Soredex(®), Tuusula, Finland) alone and CMOS plus lead foil. Radiation dose was measured after a full-mouth periapical series (14 radiographs) using the long-cone paralleling technique. Lithium fluoride (LiF 100) thermoluminescent dosemeters were placed in an anthropomorphic phantom at points corresponding to the tongue, thyroid, crystalline lenses, parotid glands and maxillary sinuses. RESULTS: Dosemeter readings demonstrated the efficacy of the addition of lead foil in the intraoral digital X-ray systems provided in reducing organ doses in the selected structures, approximately 32% in the PSP system and 59% in the CMOS system. CONCLUSIONS: The use of lead foils associated with digital X-ray sensors is an effective alternative for the protection of different anatomical sites of the head and neck during full-mouth periapical series acquisition.

Influence of the intergonial distance on image distortion in panoramic radiographs.

OBJECTIVES: The aim of this study was to evaluate the influence of the intergonial distance during the formation of panoramic radiographic images by means of horizontal and vertical measurements. METHODS: 30 macerated mandibles were categorized into 3 different groups (n = 10) according to their intergonial distances as follows: G1, mean distance 8.2 cm, G2, mean distance 9.0 cm and G3, mean distance 9.6 cm. Three metal spheres 0.198 cm in diameter and placed at an incline using an isosceles triangle were separately placed over the internal and external surfaces of the mandibles before radiographic exposure for the purpose of taking the horizontal and vertical measurements. The occlusal planes of the mandibles were horizontally placed on the chin rest of the panoramic machine Orthopantomograph® OP 100 (Instrumentarium Imaging, Tuusula, Finland) and were then radiographed. In the panoramic radiographs, an expert radiologist measured the distances between the metal spheres in the horizontal and vertical directions using a digital caliper. The data were tabled and statistically analysed by Student's t-test and analysis of variance with Tukey post-test (α = 0.05). RESULTS: In all three groups magnification of the distances between spheres was observed when compared with the real distance in both horizontal and vertical measurements (p < 0.05). Differences in both horizontal and vertical measurements were observed between the different regions (p < 0.05), however there were no differences between groups in the same region (p > 0.05). Differences between horizontal and vertical measurements were observed in different regions in all evaluated groups (p < 0.05). CONCLUSION: The intergonial distance is a factor that had no influence on image formation in the panoramic radiograph.

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.

Alternative X-ray filters for an intra-oral digital radiographic system.

OBJECTIVE: The aim of this study was to evaluate the effect of the modulation of the radiation spectrum with the use of alternative X-ray filters in the quality of intra-oral digital images from storage phosphor plates. METHODS: The radiographic exposures were performed in a GE 1000 X-ray machine (General Electric Co., Milwaukee, WI), operating at 65 kVp, 10 mA, 40 cm focus receptor distance using three different exposure times: 0.05 s, 0.16 s and 0.35 s. The control filter (GC) was 100% aluminium (Al) with a thickness of 1.5 mm. The tested filters were: G1, 97% Al and 3% copper (Cu) with 1.47 mm thickness; G2, 96% Al and 4% Cu with 1.53 mm thickness; G3, 95% Al and 5% zinc (Zn) with 1.56 mm thickness; G4, 98% Al and 2% Zn with 1.5 mm thickness; and G5, 95% Cu and 5% Zn with 1.6 mm thickness. For formation of the image, a 12-step Al wedge (each step with increments of 1 mm in thickness) was radiographed 10 times. Pixel values measured in digital images were converted into optical density (OD). RESULTS: All replicates showed OD with high reproducibility (r > 0.95) for all exposure times and tested filters. In comparison between filters, statistically significant differences in density (p < 0.05) were observed. The OD curve of the G5 filter in all exposure times and G3 filter in an exposure time of 0.05 s showed changes in shape (p < 0.05). CONCLUSIONS: Excluding the G5 filter, all others tested filters can be used as a substitute for GC without losses in image quality.

Comparison of digital systems and conventional dental film for the detection of approximal enamel caries.

OBJECTIVES: The aims of this study were (1) to compare the accuracy of the detection of approximal enamel caries lesions using three intraoral storage phosphor plate digital systems and one conventional film-based radiographic system; and (2) to determine whether there is a correlation between the histological and radiographic measurements of enamel caries. METHODS: 160 approximal surfaces were radiographed under standardized conditions using three storage phosphor stimulable systems (DenOptix and Digora FMX with white and blue plates), and one film system (Insight film). 17 observers scored the images for the presence and depth of caries using a 4-point scale. The presence of caries was validated histologically (gold standard). Two-way analysis of variance was used to test the differences in sensitivity, specificity and overall accuracy (TP + TN). The data from the radiographic and histological measurements were statistically analysed by Spearman's rank correlation coefficient. RESULTS: Two-way analysis of variance and the post hoc t-test demonstrated that Digora (white plate) had higher specificity and overall accuracy values than DenOptix (P = 0.021); there was no statistically significant difference among the other imaging modalities (P > 0.05). There was no significant correlation between the histological depth measurements and the radiographic measurements from Digora (blue plate) (P = 0.43), Digora (white plate) (P = 0.15), DenOptix (P = 0.17) and Insight film (P = 0.06). CONCLUSIONS: The results suggest that (1) the performance of the three storage phosphor image plate systems was similar to that of the Insight film for detection of approximal enamel caries, and (2) the increase in histological depth of enamel caries was not significantly correlated with radiographic measurements.

Determination of the length of zygomatic implants through computed tomography: establishing a protocol.

OBJECTIVES: The aim of this study was to establish and verify an examination protocol using CT to estimate the length of zygomatic implants, thus rendering the surgical process safer and more predictable, and exposing the patient to a minimal level of radiation. METHODS: Paracoronal CT scan was carried out on ten dry human crania (n = 20) and the zygomatic implant sites were measured (L(CT)) bilaterally. A standard surgical zygomatic implant placement procedure was carried out and the actual lengths (L(Real)) and clinical lengths (L(Clin)) determined. RESULTS: The averages of the L(CT), L(Clin) and L(Real) were 45.73 +/- 4.82 mm, 42.63 +/- 4.33 mm, and 44.73 +/- 4.53 mm, respectively. Student's t-test revealed no statistically significant differences between the L(Real) and L(CT) averages (P = 0.1532), whereas the L(Real) and L(Clin) averages were statistically different (P < 0.0001). CONCLUSIONS: The proposed protocol proved to be precise and efficacious in the determination of zygomatic implant length, with the advantage to the patient of a relatively low level of exposure to radiation due to the small quantity of tomographic slices used. Although there were no major repercussions, the clinical probe in the zygomatic implant kit commonly used in this surgical procedure proved to be a rather imprecise tool.

Comparison of transcranial radiograph and magnetic resonance imaging in the evaluation of mandibular condyle position.

OBJECTIVES: Several image modalities have been used to assess the condylar position in the glenoid fossa. However, despite the development of more advanced techniques for imaging the temporomandibular joint (TMJ), the transcranial projection remains widely used in dentistry. The purpose of this study was to compare the condylar position in transcranial radiography (TRANS) with MRI. METHODS: 70 matched pairs of TMJs (35 patients) who had undergone TRANS and MRI were evaluated. The TRANS scans were compared with the lateral, central and medial MRI scans, and the condylar position was assessed in the closed and open mouth position according to subjective and objective methods. The sensitivity, specificity and accuracy values were calculated for each group and Bowker's test was used to analyse the data. RESULTS: There was no statistical significance between TRANS and MRI (P > 0.05). However, even though there were similar mean values between them, the comparison with the lateral image showed higher values, which might be due to TRANS representing the lateral one-third of the condyle. CONCLUSIONS: It can be concluded that TRANS seems to be an acceptable method and its applicability as an adjunctive method in the condylar position should not be rejected.

Evaluation of temporomandibular joint in stress-free patients.

OBJECTIVES: The aetiology of temporomandibular disorders (TMD) is presently considered to be multifactorial, and stress has been regarded as an important factor in their onset. Many studies have evaluated the importance of stress in TMD; however, only patients with TMD and stress have been assessed. This study aimed at evaluating signs and symptoms of TMD in stress-free patients. METHODS: The temporomandibular joints (TMJs) of 40 stress-free patients were evaluated during clinical examination and in MRI. RESULTS: The individuals lived in an area without electric power supply or telephone services. They worked in agriculture and fishery. 77.5% of the patients presented normal mandibular function; 70% presented normal mandibular trajectory; 61.25% did not present sounds in TMJ and 93.75% did not present joint pain during palpation. Image screening showed that 70% of TMJ presented normal disc position. Only one patient (1.25%) presented TMD. CONCLUSIONS: The absence of stress is a strong factor for the non-development of TMD.

Tonsillolith--report of an unusual case.

Tonsilloliths are rare concretions found in the tonsillar crypt. They are usually single and unilateral, but occasionally may be multiple or bilateral. This report describes a case of a 47-year-old woman whose radiography revealed one radiopaque image located in the right ramus of the mandible. The patient revealed a history of slight dysphagia, halitosis and swallowing pain with a foreign body sensation. Her medical history revealed a tonsillectomy when she was eight years old and the removal of the uvula because of sleep apnoea six years ago. Computer tomography showed a delimited and calcified oval image measuring 0.6 x 0.6 cm. The tonsillar concretion might have been formed because of a calcification of the lymphoid tissue. On the patient's request, surgical excision was not performed and she will be monitored due to the tendency of such lesions to grow.

Poland-Moebius syndrome: a case with oral anomalies.

The combination of Moebius and Poland anomalies is rarely described in the literature. While some authors believe this association is an independent syndrome, others think that Poland, Moebius and Poland-Moebius syndromes are variations of the same condition. We report a case of Poland-Moebius syndrome in a 6-year-old girl who presented with bilateral convergent strabismus, the inability to abduct her eyes beyond the midline and brachydactyly of her right hand. Oral manifestations included incompetent lips and an abnormal tongue. Other facial features included hypoplasia of her mandible and her left ear at a slightly lower level than her right ear. Panoramic and lateral skull radiographs confirmed the absence of certain teeth and the hypoplastic mandible. The diagnosis of Poland-Moebius syndrome was made on the basis of cranial nerve involvement and oro-facial manifestations.

Fraudulent use of radiographic images.

The aim of this study was to evaluate the ability of trained observers to identify altered radiographic images after modifications using an image-editing software. Based on implantology in 10 radiographs, eight panoramic and one linear tomograph were modified while one tomograph was untouched. Implants were placed or removed and bone levels were altered, and seventy dentists were invited to identify these alterations. The results showed that the percentage of the correct answers was 12.5% or 2 identifications per examiner. The rate of false positives in relation to correct answers was at a level of 6:1. We concluded that the professionals have difficulty in identifying altered radiographs after using an image-editing software and that the seriousness of this situation demands that dentists be warned of the dangers of the use and abuse of this technology.

[Activity of phosphodiesterases in granulation tissue treated with electron irradiation -- experimental study on rats]. / Atividade das fosfodiesterases em tecido de granulação submetido a irradiação de elétrons--estudo experimental em ratos.

The present study evaluated the effect of low doses of electron radiation on the activity of phosphodiesterases in granulation tissue. In order to induce growth of granulation tissue, a PVC sponge disk was introduced under the dorsal skin of 84 Wistar rats. The rats were divided in two groups, control and irradiated. The enzymatic activity was evaluated according to the evolution of the granulation tissue after 5, 7, 10, 14, 17, 20 and 24 days. Irradiation was carried out 3 days after the implantation of the sponge, by means of a linear accelerator, with energy of 6 MeV, and dose of 1.0 Gy. The results of this study showed that 5'-nucleotidase and ATPase had their activity directly affected by irradiation only in the beginning of the tissue repairing process. Alkaline phosphatase did not suffer any direct effect of irradiation. It is possible that the main factor has been the damage of the cellular components responsible for the growth of granulation tissue, which determine the production of enzymes according to the necessity.

[Assessment of 3 radiographic methods (conventional periapical, digital periapical, and panoramic) ni the diagnosis of artificially produced periapical lesions]. / Avaliação de três métodos radiográficos (periapical convencional, periapical digital e panorâmico) no diagnóstico de lesões apicais produzidas artificialmente.

This research was carried out in order to evaluate three radiographic methods--conventional periapical, digital periapical and panoramic--in the diagnosis of artificially produced periapical lesions. For this purpose, 5 mandibles, with lesions produced by means of spherical drills of different sizes, were used. The research was divided into five distinct phases, as follows: phase Z (initial)--characterized by the absence of lesion; phase R--lesion produced with a number 6 drill; phase J--lesion produced with a number 8 drill; phase D--lesion produced with a number 10 drill; and phase H--lesion reaching the vestibular cortex. The lesions were produced in quadrants. Radiographs were made after each phase and analyzed by 4 experts in radiology. For the digital system there was statistically significant difference in phase R (in the region of incisors) and in phase H (in the region of premolars). In the region of molars there was statistically significant difference in phase D for panoramic radiography. It must be pointed out that panoramic radiography produced the less effective results in phase H.

Clinical study of the sensitivity and dynamic range of three digital systems, E-speed film and digitized film.

The objective of the present study was to clinically evaluate the sensitivity and dynamic range of three digital systems (Sens-A-Ray, CDR, Digora), digitized film and E-speed film. Five objects were submitted to three different kilovoltages and seven exposure times. In order to evaluate the relationship between exposure time and dosage, measurements were made in a dental x-ray unit with an ion chamber, X-ray timer and kVp meter. For each system, 105 radiographs were taken, totalling 525 images, that were evaluated by six trained observers by means of scoring from 0 to 4. The scores attributed to the images for each of the systems were submitted to analysis of variance and Turkey's test. The results showed statistically significant differences (p < 0.01) with the storage phosphor system producing the wider dynamic range, followed by the digitized film. The CDR system showed the greater sensitivity, followed by the Digora system.

[Clinical and comparative study of the image quality of 3 digital radiographic systems, E-speed film and digitalized film]]. / Estudo clínico comparativo da qualidade de imagem de três sistemas radiográficos digitais, filme E-speed e filme digitalizado.

The aim of this study was to evaluate, subjectively, the image quality of two CCD digital systems, a digital storage phosphor system, a digitized film and an E-speed film. Five objects were radiographed with 50, 60 and 70 kVp, with exposure times of 0.08, 0.13, 0.2, 0.4 and 0.8 s. In order to maximize the fidelity of the results, the dental X-ray unit employed was submitted to an evaluation so that the relation between exposure time and dose could be established. A good reproducibility was obtained. Six evaluators analyzed 375 images, using a scoring scale which ranged from 0 to 4. The results revealed different responses, indicating that the storage phosphor system had the best performance, in the various exposures employed. However, it was possible to conclude that all systems studied, except for the Sens-A-Ray, can offer images in ideal conditions for the diagnosis, as long as their latitudes are respected.

Comparative study of two digital radiographic storage phosphor systems.

The objective of this study was to evaluate the image quality and dynamic range of two digital radiographic storage phosphor systems: Digora (Soredex, Finland) and DenOptix (Gendex, USA). Four objects were analyzed and eight exposure times employed, totaling 64 images that were analyzed by 5 examiners using a scale from 1 to 4 to classify the images. The scores were submitted to analysis of variance and the results showed statistical differences among the averages attributed to the systems, to the exposition times and to the objects (p 0.01 Pound). Digora presented a larger dynamic range and, in general, a better image quality. Although these 2 systems present the same photon detector, they present different results in relation to the evaluated items.

[Variation in enzymes in radiated ocular globes of dogs. Use of low doses and thermoluminescent dosimetry]. / Estudo da variação de enzimas, provocadas pelo emprego da radiação no globo ocular de cães. Utilização de baixas doses e dosimetria termoluminescente.

The authors are worried about the effect of X radiation the abtainment of intra oral radiographies and in the own the equipment for thermoluminescent dosimetry they proposed to realise the study when they irradiated the dog's eye ball to check the possible alterations in the enzymesystems after irradiation time, they could relate the effects of the low doses radiation that reach in the patient's eye during the routine radiographic exam. The determination of the dose radiation was realized with thermoluminescent dosimeter which has high sensibility and this are the enzymes that were studied: Glutathione Reductase, Glucose-6-Phosphatase Dehydrogenase, N-Acetyl Hexosaminidase e Acid Phosphatase.