João César Guimarães Henriques

Optimization of dental CBCT exposures through mAs reduction

OBJECTIVESnTo investigate the effect of tube current-exposure time (mAs) reduction on clinical and technical image quality for different CBCT scanners, and to determine preliminary minimally acceptable values for the mAs and contrast-to-noise ratio (CNR) in CBCT.nnnMETHODSnA polymethyl methacrylate (PMMA) phantom and an anthropomorphic skull phantom, containing a human skeleton embedded in polyurethane, were scanned using four CBCT devices, including seven exposure protocols. For all protocols, the mAs was varied within the selectable range. Using the PMMA phantom, the CNRAIR was measured and corrected for voxel size. Eight axial slices and one coronal slice showing various anatomical landmarks were selected for each CBCT scan of the skull phantom. The slices were presented to six dentomaxillofacial radiologists, providing scores for various anatomical and diagnostic parameters.nnnRESULTSnA hyperbolic relationship was seen between CNRAIR and mAs. Similarly, a gradual reduction in clinical image quality was seen at lower mAs values; however, for several protocols, image quality remained acceptable for a moderate or large mAs reduction compared with the standard exposure setting, depending on the clinical application. The relationship between mAs, CNRAIR and observer scores was different for each CBCT device. Minimally acceptable values for mAs were between 9 and 70, depending on the criterion and clinical application.nnnCONCLUSIONSnAlthough noise increased at a lower mAs, clinical image quality often remained acceptable at exposure levels below the manufacturers recommended setting, for certain patient groups. Currently, it is not possible to determine minimally acceptable values for image quality that are applicable to multiple CBCT models.

Non-syndromic keratocystic odontogenic tumor involving the maxillary sinus: case report

INTRODUCTION: The odontogenic keratocyst tumor is rarely found in maxilla. CASE REPORT: This article describes a report of a case of a 60-year-old Caucasian female with an asymptomatic growth in the region of the posterior maxilla tumor diagnosed as odontogenic keratocyst. We discuss the diagnosis and workup for this type of injury.

Evaluation of renal osteodystrophy in the dental clinic by assessment of mandibular and phalangeal cortical indices

ObjectivesSecondary hyperparathyroidism (SHPT) is a disease that affects patients with chronic kidney disease, and is characterized by mineral disturbance and bone loss, known as renal osteodystrophy. The aim of this study was to assess the validity of using intraoral phosphor storage plates to take radiographs of the middle phalanges to evaluate bone loss resulting from SHPT during follow-up of these patients.MethodsThe sample consisted of 24 patients with chronic kidney disease, 12 with parathyroid hormone (PTH) levels ≥500xa0pg/ml, and 12 with PTH levels <500xa0pg/ml, who underwent hemodialysis weekly. For each patient, a panoramic radiograph and digital radiographs of the ring, index, and middle fingers of both hands were taken. The Mandibular Cortical Index (MCI) and the Trabecular Bone Pattern Index (TBP) were applied to the panoramic radiographs, while the Phalangeal Cortical Index (PCI) was applied to the digital radiographs of the phalanges. Three evaluators performed all analyses.ResultsSignificant correlations were found between the PTH levels and the MCI (pxa0=xa00.023), the PCI (pxa0=xa00.039) and the TBP index (pxa0=xa00.032). These parameters were also significantly interrelated (MCIxa0×xa0PCIxa0=xa00.001; MCIxa0×xa0TBPxa0=xa00.004 and PCIxa0×xa0TBPxa0=xa00.009). The PCI was shown to have the highest correlation with PTH levels.ConclusionIn patients with chronic renal disease, it is clinically relevant to use panoramic and digital radiographs using intraoral storage plates to assess a number of quantitative parameters that can be linked to PTH levels.

A abordagem e o tratamento de um ameloblastoma unicístico na mandíbula - doi:10.5020/18061230.2006.p247

Among the complex group of odontogenic tumors, the ameloblastoma points out as the most important and common odontogenic tumor of epithelial origin. It consists mainly of a benign tumor, slow in progress and locally invasive, although it can present high rates of reincidence. The unicystic ameloblastoma is one of the tumor variants and deserves singular consideration for its peculiar characteristics. This study aimed at showing the peculiarities of this ameloblastoma variant through a case report on the care assistance of a young man committed by a jaw tumor, approaching the diagnostic methods used and the applied treatment. Based on present, we conclud that the prognostic for patients with unicystic ameloblastoma is very favorable, since the propaedeutic proceedings are well conducted by the professionals involved.