Development of an open project rectangular collimator for use with intraoral dental X-ray unit.

In this work, an open beam-limiting device, consisting of a rectangular collimator to be coupled to an intraoral dental X-ray device, was made using recycled lead sheets as a radiation-absorbing element. The collimator was designed for 3D printing, and using Spektr 3.0 software, the number of lead sheets needed to absorb excess radiation was calculated. The rectangular collimator reduced the radiation dose to patients by 65% when using four layers of recycled lead sheets (saturating with a 70% reduction in radiation dose at the limit of eight or more sheets of lead). The rectangular collimator does not negatively impact the quality of the radiological image, is available as an open design for 3D printing, and can be built with materials that are easily accessible to the dentist, facilitating its use in clinical practice and reducing the patient's exposure to ionizing radiation.

Comparison of panoramic radiography and CBCT to identify maxillary posterior roots invading the maxillary sinus.

OBJECTIVES: Given the limitations of panoramic radiography for assessing topographic relationship of maxillary teeth with sinus floor, the purpose of this study was to assess signs on panoramic radiography that could predict root protrusion into the sinus. METHODS: A total of 46 individuals (330 maxillary posterior teeth) who underwent panoramic radiography and CBCT were enrolled. The relationship between the posterior teeth and the maxillary sinus and panoramic radiography signs (projection of the root apices, interruption of the maxillary sinus floor, lamina dura, darkening in the root apices, and superiorly curving sinus floor enveloping the associated tooth root) associated with protrusion of root apices into the sinus were evaluated. RESULTS: There were differences between the imaging modalities about the positioning of the root apices regarding the sinus (p < 0.05). Only the projecting of the root apices and the interruption of the sinus floor on panoramic radiography were predictors for the root protrusion (p < 0.05). No significant association was observed for the other panoramic radiography signs (p > 0.05). CONCLUSIONS: The root projection into the sinus and the interruption of the sinus floor are indicative signs of root protrusion into the sinus on CBCT.

Influence of cone-beam computed tomography image artifacts on the determination of dental arch measurements.

OBJECTIVE: To compare dental plaster model (DPM) and cone-beam computed tomography (CBCT) in the measurement of the dental arches, and investigate whether CBCT image artifacts compromise the reliability of such measurements. MATERIALS AND METHODS: Twenty patients were divided into two groups based on the presence or absence of metallic restorations in the posterior teeth. Both dental arches of the patients were scanned with the CBCT unit i-CAT, and DPMs were obtained. Two examiners obtained eight arch measurements on the CBCT images and DPMs and repeated this procedure 15 days later. The arch measurements of each patient group were compared separately by the Wilcoxon rank sum (Mann-Whitney U) test, with a significance level of 5% (α  =  .05). Intraclass correlation measured the level of intraobserver agreement. RESULTS: Patients with healthy teeth showed no significant difference between all DPM and CBCT arch measurements (P > .05). Patients with metallic restoration showed significant difference between DPM and CBCT for the majority of the arch measurements (P > .05). The two examiners showed excellent intraobserver agreement for both measuring methods with intraclass correlation coefficient higher than 0.95. CONCLUSION: CBCT provided the same accuracy as DPM in the measurement of the dental arches, and was negatively influenced by the presence of image artifacts.