Sangsom Prapayasatok

Assessment of vertical root fractures using three imaging modalities: cone beam CT, intraoral digital radiography and film

OBJECTIVES The aim of this study was to assess the accuracy of cone beam CT (CBCT) in detecting vertical root fractures and to compare the accuracy with images from an intraoral sensor and from conventional intraoral film. METHODS 60 extracted, single-rooted human teeth were divided equally into two groups: a control group of 30 teeth and an induced fracture group of 30 teeth. All teeth were randomly placed into sockets in six dry mandibles. Each tooth was imaged by three modalities: CBCT, intraoral digital radiography and intraoral F-speed film. Three beam angulations (an orthogonal projection and additional projections with ± 20° horizontal shifts of the central ray) were used when radiographs were made using film and a digital sensor. Three oral and maxillofacial radiologists evaluated the presence of root fractures twice in each image modality using a five-point confidence rating scale. Areas under receiver operating characteristic curves (A(z)) were computed for each observer and modality and were tested for statistical differences using the Kruskal-Wallis test. RESULTS There was no statistical difference in the performance of the three modalities (mean of A(z) values: CBCT = 0.811, film = 0.797 and sensor = 0.775; p = 0.771). CONCLUSIONS There was no significant difference between intraoral film, a high-resolution complementary metal oxide semiconductor digital imaging system and CBCT in detecting vertical root fractures in mandibular single-rooted teeth.

Diagnostic performance of cone-beam computed tomography on detection of mechanically-created artificial secondary caries

Purpose The aim of this study was to compare the diagnostic accuracy of cone-beam computed tomography (CBCT) images and bitewing images in detection of secondary caries. Materials and Methods One hundred and twenty proximal slots of Class II cavities were randomly prepared on human premolar and molar teeth, and restored with amalgam (n=60) and composite resin (n=60). Then, artificial secondary caries lesions were randomly created using round steel No. 4 bur. The teeth were radiographed with a conventional bitewing technique and two CBCT systems; Pax-500ECT and Promax 3D. All images were evaluated by five observers. The area under the receiver operating characteristic (ROC) curve (Az) was used to evaluate the diagnostic accuracy. Significant difference was tested using the Friedman test (p value<0.05). Results The mean Az values for bitewing, Pax-500ECT, and Promax 3D imaging systems were 0.882, 0.995, and 0.978, respectively. Significant differences were found between the two CBCT systems and film (p=0.007). For CBCT systems, the axial plane showed the greatest Az value. Conclusion Based on the design of this study, CBCT images were better than bitewing radiographs in detection of secondary caries.

Accuracy of an equation for estimating age from mandibular third molar development in a Thai population

Purpose This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. Materials and Methods The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subjects age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Results Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, P≤0.01). 50% of age estimates in the second part of the study fell within a range of error of ±1 year, while 75% fell within a range of error of ±2 years. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. Conclusion The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

Infection control and patient discomfort with an alternative plastic barrier in intraoral digital radiography

OBJECTIVES (1) To compare the efficacy of a commercially available hygienic sheath and an alternative plastic bag in preventing contamination of the imaging plate during intraoral radiography and (2) to compare patient discomfort when using the hygienic sheath and the plastic bag. METHODS 60 sterilized Size 2 imaging plates covered with either the hygienic sheath (n = 30) or the plastic bag (n = 30) were used to simulate digital periapical radiographic examination in 30 volunteer patients. After disinfection, each plate was swabbed. The swabbed medium was then plated on trypticase soy agar and incubated. Bacterial colonies were counted. Patient discomfort was assessed using a visual analogue scale (VAS) score. The comparison of the number of bacterial colonies and VAS scores between the two groups was tested by paired t-test at p < 0.05. RESULTS There was no significant difference in the number of bacterial colonies between the two groups (p = 0.745). Of all the plates, 10% plates yielded bacterial colonies. The mean count of bacterial colonies for both groups was 10-20 CFU ml-1. However, there was a significant difference between VAS scores for the two systems (p = 0.000). The mean VAS scores (range 0-10) for patient discomfort for the hygienic sheath group and the plastic bag group were 3.03 and 5.33, respectively. CONCLUSIONS Based on the design of this study, the alternative barrier provided similar results to those commercially available. Regarding the type of barrier envelope, the hygienic sheath induced less discomfort than the plastic bag.