Comparative study on radio-opacity of dental composite resin materials'determination using film imaging and digital imaging / 北京大学学报(医学版)

OBJECTIVE@#To compare the effects of different imaging methods on radio-opacity. Digital imaging and traditional film imaging were used to determine the radio-opacity of dental composite resin materials.@*METHODS@#Fourteen dental composite resins commonly used in clinic were prepared for disc samples with thickness of 1 mm and diameter of 15 mm respectively. The aluminum step wedge was used as the reference and the disc samples were irradiated with X-rays by the traditional film imaging, phosphor imaging plate and charge-coupled device(CCD) intra-oral X-ray sensor respectively. Exposure was set at 65 kV and 7 mA, with 300 mm focus to film distance and the exposure time was 0.25 s. After developing and fixing the film, the optical density of the image of the sample and that of each step of the aluminum step wedge were measured using the densitometer. The digital image file was exported to grey scale analysis software of Adobe Photoshop® to measure the average grey value in the sample image and aluminum step wedge image. The curves were drawn corresponding to the optical density/gray value of each step of the aluminum step wedge and its thickness, and the equivalent thickness of the aluminum plate was calculated according to the optical density/gray value of the actual measured thickness of the sample, so as to evaluate the radio-opacity of dental composite resin material.@*RESULTS@#For the same sample, the aluminum equivalent measured by traditional film imaging and two other digital imagings had significant differences among the 14 composite resins (P < 0.05), and the aluminum equivalent measured by the two digital imagings were greater than that of the traditional film. Moreover the aluminum equivalent measured by the two digital imagings was also different, and the aluminum equivalent measured by the CCD intra-oral X-ray sensor in most composite resins was larger than that measured by phosphor imaging plate. The same sample was photographed with the same imaging method, and the aluminum equivalent was different after three exposures. The standard deviation of aluminum equivalent measured by phosphor imaging plate was the largest, while that measured by CCD intra-oral X-ray sensor was the smallest. Among the 14 dental composite resin materials, the aluminum equivalent of Tetric N-Ceram and Te-Econom Plus measured by traditional film imaging and phosphor imaging plate was significantly higher than other composite resins.@*CONCLUSION@#Based on clinical significance, three kinds of sensors designed to measure the radio-opacity of dental composite resin, the value of aluminum equivalent will change according to different types of sensors. The aluminum equivalent measured by CCD intra-oral X-ray sensor was higher than that measured by phosphor imaging plate, and the aluminum equivalent measured by phosphor imaging plate was higher than that measured by traditional film imaging. Moreover, even though the same sensor was used, the aluminum equivalent measured by multiple exposures was different. The standard deviation of the aluminum equivalent measured by phosphor imaging plate was greater than that measured by traditional film imaging and CCD intra-oral X-ray sensor. The three sensors in this study could be used for evaluating the radio-opacity of dental composite resin materials. But no matter what kind of sensor was used to measure the radio-opacity of dental composite resin, it complied to ISO 4049: 2019 standard, the materials were suitable for clinical use.

Spectrum of imaging findings in trans-gastric migration of accidently ingested metallic foreign bodies

Background: An accidently ingested foreign body may get lodged within the lumen of gastrointestinal tract, pass uneventfully with feces or may migrate extraluminally into the surrounding tissues in which case it may lead to suppurative or vascular complications. The aim of the endeavor was to study the spectrum of imaging findings in patients with accidental ingestion of foreign bodies with trans-gastric migration of metallic foreign bodies.Methods: Total 33 patients with history of accidental ingestion of foreign bodies were subjected to preliminary radiograph of neck, chest and abdomen followed by upper gastrointestinal endoscopy. Failure to retrieve/ localize foreign body endoscopically from upper gastrointestinal tract with check radiograph reiterating the presence of foreign body in upper abdomen were subjected to computed tomography of abdomen.Results: A total of 33 patients comprising of 27 females and 6 males with mean age of 23.76 years with history of foreign body ingestion were studied. Ingested foreign bodies were lodged in pharynx (n=7), esophagus (n=3), stomach (n=13) or duodenum (n=3). In 7 patients in whom endoscopy failed to locate and/or retrieve foreign body, computed tomography confirmed the presence of trans-gastrically migrated foreign body in the surrounding structures. The location of migrated foreign bodies was in lesser sac (n = 2), greater omentum (n = 3), lesser omentum (n = 1) and transmural (n = 1). Two patients had evidence of collection formation around the migrated foreign bodies.Conclusions: Sharp or pointed metallic foreign bodies may migrate trans-luminally with various implications. Though radiography is the preliminary workhorse for the confirmation of ingested foreign bodies, computed tomography owing to its volumetric data acquisition helps in exact localization of migrated foreign bodies and should precede any therapeutic intervention for retrieval of migrated foreign bodies.

Physical properties of novel composite using Portland cement for retro-filling material / 대한치과보존학회지

OBJECTIVES: The aim of this study was to compare apical sealing ability and physical properties of MTA, MTA - AH-plus mixture (AMTA) and experimental Portland cement - Epoxy resin mixture (EPPC) for a development of a novel retro-filling material. MATERIALS AND METHODS: Forty-nine extracted roots were instrumented and filled with gutta-percha. Apical root was resected at 3 mm and the retro-filling cavity was prepared for 3 mm depth. Roots were randomly divided into 3 groups of 15 roots each. The retro-filling was done using MTA, AMTA, and EPPC as the groups divided. Four roots were used as control groups. After setting in humid condition for 24 hours, the roots were immersed in 1% methylene blue dye solution for 72 hours to test the apical leakage. After immersion, the roots were vertically sectioned and photos were taken to evaluate microleakage. Setting times were measured with Vicat apparatus and digital radiographs were taken to evaluate aluminum equivalent thickness using aluminum step wedge. The results of microleakage and setting time were compared between groups using one-way ANOVA and Scheffe's post-hoc comparison at the significance level of 95%. RESULTS: AMTA and EPPC showed less microleakage than MTA group (p < 0.05). AMTA showed the highest radio-opacity than other groups and the novel EPPC showed 5 mm aluminum thickness radio-opacity. EPPC showed the shortest initial and final setting times than other groups while the MTA showed the longest (p < 0.05). CONCLUSIONS: Under the condition of this study, the novel composite using Portland cement-Epoxy resin mixture may useful for retro-filling with the properties of favorable leakage resistance, radio-opacity and short setting time.

Gas diffusion effect on Nifedipine in coal workers pneumoconiosis by radio-opacity size / 예방의학회지

Carbon monoxide diffusing capacity(DLco) was evaluated before and after nifedipine administration in coal workers' pneumoconiosis by the size of radioopacity. Nifedipine was administered to 18 men and 17 men of small round opacity group and large opacity group respectively. Placebo was administered to 19 men and 15 men of small and large opacity group respectively. In large opacity group DLco was increased after nifedipine administration. But, it was not significant statistically(0.05 < p < 0.01). In other groups, there were no significance difference between and after medication.