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[en] To determine whether subtraction images utilizing contrast media can improve the diagnostic performance of proximal caries diagnosis compared to conventional periapical radiographic images. Thirty-six teeth with 57 proximal surfaces were radiographied using a size no.2 RVG-ui sensor (Trophy Radiology, Marne-la-Vallee, France). The teeth immersed in water-soluble contrast media and subtraction images were taken. Each tooth was then sectioned for histologic examination. The digital radiographic images and subtraction images were examined and interpreted by three dentists for proximal caries. The results of the proximal caries diagnosis were then verified with the results of the histologic examination. The proximal caries sensitivity using digital subtraction radiography was significantly higher than simply examining a single digital radiograph. The sensitivity of the proximal dentinal carious lesion when analyzed with the subtraction radiograph and the radiograph together was higher than with the subtraction radiograph or the radiograph alone. The use of subtraction radiography with contrast media may be useful for detecting proximal dentinal carious lesions.
[en] This study aimed to investigate the effect of changing the kilovoltage peak (kVp) on the radiographic assessment of dental caries. Seventy-five extracted posterior teeth with proximal caries or apparently sound proximal surfaces were radiographed with conventional E-speed films and a photostimulable phosphor system using 60 kVp and 70 kVp for the caries assessment. The images were evaluated by three oral radiologists and compared with the results of the stereomicroscope analysis. No statistically significant difference was found between 60 kVp and 70 kVp for the caries detection, determination of caries extension into dentin, and caries severity in either the conventional or the digital images. Good to very good inter-observer and intra-observer agreements were found for both kilovoltage values on the conventional and digital images. Changing the kilovoltage between 60 kVp and 70 kVp had no obvious effect on the detection of proximal caries or determination of its extension or severity.
[en] During the last three to four decades, extensive changes in opinion concerning the etiology, pathogenesis, and treatment of periodontal disease have taken place. During these decades, contributing factors are standardized and controlled trials, as well as epidemiological studies, were performed. Periodontics is no longer an art as it was at the end of the 19th century- it is a science based on research. Pyorrhea alveoiaris or periodontitis has been considered a multifactorial disease with bad prognosis which, together with caries, causes loss of teeth in the population. It was supposed to affect most of the population with age progress, trauma from occlusion, systemic diseases, and bad oral hygiene. The discovery that plaque was the cause of gingivitis, and that the subgingival microflora differed in composition between sites, teeth, and individuals created new suggestions and demands for the treatment of periodontal disease. The aim of this paper is to summarize some modern aspects on periodontal disease. (author)
[en] The purpose of this study was to evaluate the initial and postoperative radiographic features of the endodontic treated teeth. The author examined the radiographs which comprise 114 teeth with 155 canals of 64 persons. The following factors were considered; Age, sex, tooth location, number of root canal, postoperative periods, initial diagnosis, and radiographic findings, postoperative radiographic findings. The apical levels of the root fillings were 76.8% to apex, 19.0% underfilling, 3.9% overfilling. The following results were obtained. 1. Of the 93 teeth which revealed initial periapical rarefaction, 66 teeth(71.0%) had showed complete bone healing, 19 teeth (20.4%) decreased rarefaction, 6 teeth (6.5%) no change, 2 teeth (2.2%) increased rarefaction after 20.0 months mean healing time. 2. 21 teeth which had on initial periapical rarefaction showed no occurrence of new periapical rarefaction. 3. Of the 66 teeth completely healed, 53 teeth (80.3%) had showed reappearance of laminadura, 64 teeth (97.0%) reappearance of periodontal ligament space after 23.4 months mean healing time.
[en] The purpose of this study was to investigate how to detect proximal caries using line profile and validate linear measurements of proximal caries lesions by basic digital manipulation of radiographic images. The X-ray images of control group (15) and caries teeth (15) from patients were used. For each image, the line profile at the proximal caries-susceptible zone was calculated. To evaluate the contrast as a function of line profile to detect proximal caries, a difference coefficient (D) that indicates the relative difference between caries and sound dentin or intact enamel was measured. Mean values of D were 0.0354 ± 0.0155 in non-caries and 0.2632 ± 0.0982 in caries (p<0.001). The mean values of caries group were higher than non-caries group and there was correlation between proximal dental caries and D. It is demonstrated that the mean value of D from caries group was higher than that of control group. From the result, values of D possess great potentiality as a new detection parameter for proximal dental caries.
[en] The aim of this study was to radiographically assess the different types of post made by undergraduate dental students. Study sample were collected in 2007 from the existing dental records of 272 patients who received treatment with different types of post and crowns between September 2004 and May 2007. The treatment was performed according to the classical prosthodontic guidelines. All radiographs were scanned and measurements were made using special computer software (ImageToolR). Radiographs of 150 teeth with posts were evaluated: 119 teeth with cast post and core, and 31 teeth with prefabricated post. The remaining apical gutta percha (RAGP) was acceptable in 142 teeth (94.7%). Teeth with no gap between tip of the post and gutta-percha (GP) was 81 teeth (54%), 60 teeth (40%) with gap less than 2 mm and 9 teeth (6%) with a gap more than 2 mm. The long axis of the post coincided with the long axis of the root in 125 teeth (83.3%). Post length to crown length ratio was 1:1 or more in 107 teeth (71.3%) while in 43 teeth (28.7%), the ratio was less than one. Fifty-two teeth (34.7%) showed unacceptable width while 92 teeth (65.3%) showed acceptable width in the coronal third. In the middle third, 26 teeth (17.3%) showed unacceptable width and 124 teeth (82.7%) showed acceptable width. In the apical third, 12 teeth (8%) had unacceptable post width while 138 teeth had acceptable post width.: This study showed that the radiographic features of the cases made by the undergraduate dental students were mostly satisfactory. (author)
[en] Tooth length determination is a crucial step in endodontic treatment. Traditionally, radiographs are used to confirm working length of the root length. This study was performed to evaluate the radiographic distortion (magnification) and calculate correction coefficients for the object-film distance. Ninety-six radiographs were made of eight extracted teeth (two upper first premolars, two lower first premolars, two upper first molars, and two lower first molars) by using the 16 inch long cone paralleling techniques with 1 mm interval from 5 to 16 mm tooth-film distance. The following results obtained; 1. The least mean radiographic distortion from 5 to 16 mm tooth-film distance was 2.42 ±0.68% (the length of mesiobuccal cusp-mesial root of lower first molars), the greatest distortion was 4.74 ±1.36% (the length of mesiobuccal cusp-mesiobuccal root of upper first molars). 2. The greatest correction coefficient was 0.986 (the mesiobuccal cusp-mesial root of lower molars, the lowest one was 0.937 (the mesiobuccal cusp-mesiobuccal root of upper first molars).
[en] The clearance between two teeth is one of the most clinical manifestations of malocclusion. The open vertical loop is mostly used for the closing and opening of the clearance between two deformed teeth. The shape of the open vertical loop can greatly affect the orthodontic force. At present, the design of the open vertical loop depends entirely on the experience of the orthodontic doctors; this practice is ineffective and may easily hurt patients. To solve these problems, the orthodontic-force prediction model is established to help doctors calculate the orthodontic force generated by the open vertical loop using known parameters, such as the height and the clearance length. The structure of the open vertical loop is analysed, and the theory of the bending deformation of the equivalent beam is used for the analysis of the relationship between the orthodontic force and the effective parameters. The orthodontic-force measuring device of the open vertical loop with a one-dimensional force sensor was designed according to the characteristics of orthodontic force transmission. The orthodontic-force measuring experiments were conducted with open vertical loops of different parameters. Finally, the effective orthodontic-force prediction model of the open vertical loop was established by developing the correction factors in order to eliminate the errors. The average relative error rate of the theoretical value of the orthodontic-force prediction model ranged between 1.25 and 8.34%.
[en] The geometrically standardized intraoral radiographs using 5 occlusal registration material were taken serially from immediate, 1 day, 2, 4, 8, 12 and 16 weeks after making the bite blocks. The qualities of those subtracted images were evaluated to check the degree of reproducibility of each impression material. The results were as follows: 1. The standard deviations of the grey scales of the overall subtracted images were 4.9 for Exaflex, 7.2 for Pattern resin, 9.0 for Tooth Shade Acrylic, 12.2 for XCP only, 14.8 for Impregum. 2. The standard deviation of the grey scales of the overall subtracted images were grossly related to those of the localized horizontal line of interest. 3. Exaflex which showed the best subtracted image quality had 15 cases of straight, 14 cases of wave, 1 case of canyon shape. Impregum which showed the worst subtracted image quality had 4 cases of straight, 8 cases of wave, 18 cases of canyon shape respectively.
[en] The purpose of this study was to quantitatively evaluated experimental tooth root resorption for digital radiography. For this study, experimentally three root sites were used, and radiograms were taken with standardized apparatus. Digital imaging system were consisted of NEC PC-9801 (computer), TRINITRON (monitor), SONY XC-711 CCD camera. The display monitor had a resolution of 512 X 512 pixels. The following results were obtained: 1. In the difference of the four X-ray film of the contrast correction, the contrast difference was one gray scale variation at mean value. 2. Viewing of the view box of the periapical radiographs, experimental tooth root resorption of the periapical area of the first premolar, middle of mesial surface of the first molar mesial root, middle of lingual surface of the first molar distal root were recognized by increased diameter. 3. On the analysis by histogram, the periapical area of the first premolar, the middle surface of the first molar mesial root were each recognized tooth root resorption of the 5,6,7 pixel, 2,4,5 pixel by increased diameter. 4. On the analysis by histogram, the middle of lingual surface of the first molar distal root was each recognized tooth root resorption of the none, 3,6, pixel by increased diameter.