Marcelo Lupion Poleti

Visibility of the mandibular canal on CBCT crosssectional images

The identification of the mandibular canal (MC) is an important prerequisite for surgical procedures involving the posterior mandible. Cone beam computed tomography (CBCT) represents an advance in imaging technology, but distinguishing the MC from surrounding structures may remain a delicate task. Objectives The aim of this study was to assess the visibility of the MC in different regions on CBCT cross-sectional images. Material and methods CBCT cross-sectional images of 58 patients (116 hemi-mandibles) were analyzed, and the visibility of the MC in different regions was assessed. Results The MC was clearly visible in 53% of the hemi-mandibles. Difficult and very difficult visualizations were registered in 25% and 22% of the hemi-mandibles, respectively. The visibility of the MC on distal regions was superior when compared to regions closer to the mental foramen. No differences were found between edentulous and tooth-bearing areas. Conclusions The MC presents an overall satisfactory visibility on CBCT cross-sectional images in most cases. However, the discrimination of the canal from its surrounds becomes less obvious towards the mental foramen region when cross-sectional images are individually analyzed.

Comparison between 3D volumetric rendering and multiplanar slices on the reliability of linear measurements on CBCT images: an in vitro study.

Objective The purpose of this study was to determine the accuracy and reliability of two methods of measurements of linear distances (multiplanar 2D and tridimensional reconstruction 3D) obtained from cone-beam computed tomography (CBCT) with different voxel sizes. Material and Methods Ten dry human mandibles were scanned at voxel sizes of 0.2 and 0.4 mm. Craniometric anatomical landmarks were identified twice by two independent operators on the multiplanar reconstructed and on volume rendering images that were generated by the software Dolphin®. Subsequently, physical measurements were performed using a digital caliper. Analysis of variance (ANOVA), intraclass correlation coefficient (ICC) and Bland-Altman were used for evaluating accuracy and reliability (p<0.05). Results Excellent intraobserver reliability and good to high precision interobserver reliability values were found for linear measurements from CBCT 3D and multiplanar images. Measurements performed on multiplanar reconstructed images were more accurate than measurements in volume rendering compared with the gold standard. No statistically significant difference was found between voxel protocols, independently of the measurement method. Conclusions Linear measurements on multiplanar images of 0.2 and 0.4 voxel are reliable and accurate when compared with direct caliper measurements. Caution should be taken in the volume rendering measurements, because the measurements were reliable, but not accurate for all variables. An increased voxel resolution did not result in greater accuracy of mandible measurements and would potentially provide increased patient radiation exposure.

Anatomical variation of the maxillary sinus in cone beam computed tomography.

Purpose. The aim of this paper is to report a case in which the cone beam computed tomography (CBCT) was important for the confirmation of the presence of maxillary sinus septum and, therefore, the absence of a suspected pathologic process. Case Description. A 27-year-old male patient was referred for the assessment of a panoramic radiograph displaying a radiolucent area with radiopaque border located in the apical region of the left upper premolars. The provisional diagnosis was either anatomical variation of the maxillary sinuses or a bony lesion. Conclusion. The CBCT was important for an accurate assessment and further confirmation of the presence of maxillary septum, avoiding unnecessary surgical explorations.

Dimensional changes of dental arches produced by fixed and removable palatal cribs: A prospective, randomized, controlled study

OBJECTIVE To evaluate the dimensional changes of dental arches on digital models of open bite treatment with fixed and removable palatal cribs. MATERIALS AND METHODS The sample comprised 41 patients of both sexes who were white, aged 7-10 years, and who had mixed dentition, Angle Class I molar relationship, and a negative overbite of at least 1 mm. The sample was randomly divided into two groups: G1, fixed palatal crib; and G2, removable palatal crib. Cast models, obtained initially (T1) and after 1 year of treatment (T2), were scanned by a three-dimensional (3D) scanner, 3Shape R700, producing a 3D image. Measurements were performed by a calibrated examiner using OrthoAnalyzer™ 3D software. RESULTS At T2-T1, differences were observed between the groups regarding vertical dentoalveolar development and overjet. There was more mandibular incisor extrusion for G1 (-1.66 mm) than for G2 (-0.54 mm). An overjet increase was observed in G1 (0.56 mm), in contrast to a reduction in G2 (-0.40 mm). There was a similar overbite increase for both groups (3.51 mm for fixed palatal crib and 3.88 mm for removable palatal crib). CONCLUSIONS Both the treatment protocols are similarly effective for anterior open bite correction, providing an overbite increase with dentoalveolar arch changes, especially in the anterior region.

Can Bone Thickness and Inter-Radicular Space Affect Miniscrew Placement in Posterior Mandibular Sites?

PURPOSE The proper angle of miniscrew insertion is important for cortical anchorage, patient safety, and biomechanical control. The purposes of this study are to report the alveolar process thickness and inter-radicular space in the posterior region of the mandible, to assess the impact of different miniscrew insertion angle protocols, and to identify differences between the genders or types of malocclusion. MATERIALS AND METHODS In this retrospective study, 100 individuals were selected for orthodontic treatment at a radiology clinic. Cone-beam computed tomography data were imported into 3-dimensional software. The predictor variable was the location in the mandible and insertion angle. The demographic variables collected included age, gender, and malocclusion (Angle Classes I and II). The primary outcome variables were bone thickness and inter-radicular space. The inter-radicular spaces were evaluated 5 mm from the cement-enamel junction. The bone thicknesses were taken at 45°, 60°, and 90° in relation to the alveolar ridge, simulating a miniscrew insertion. These factors were evaluated for sexual dimorphism and malocclusion (Angle Classes I and II). Sexual dimorphism and malocclusion were evaluated with t tests. To compare the inter-radicular space and the thickness of bone between areas, an analysis of variance for repeated measures was used. RESULTS The sample was composed of 100 patients with a mean age of 17.4 ± 6.74 years. There were 61 female and 39 male patients and 60 Class I and 40 Class II molar relationships. The inter-radicular space ranged from 2.46 to 3.31 mm, and alveolar bone thickness ranged from 8.01 to 13.77 mm. The thickness tended to decrease with the increase in insertion angle from 45° to 90°. No significant differences between the genders or types of malocclusion were found. CONCLUSIONS The results of this study suggest that the safest areas for the placement of miniscrews are between the first and second premolars and between the first and second molars, regardless of the angle of insertion.

Associação entre Polimorfismos dos Genes AMELX e ENAMEN e Cárie Dentária em Crianças de Londrina-PR

Introdução: Para o desenvolvimento da doença cárie são necessários diversos fatores que atuam em conjunto para que ela se instale. Para sua prevenção deve-se tentar englobar o maior número possível de fatores envolvidos, sendo os principais: a higiene bucal, alimentação e o controle das principais bactérias cariogênicas. Atualmente, estudos tem provado que há a influência genética na suscetibilidade do hospedeiro, principalmente nos genes que codificam a enamelina e amelogenina. O objetivo do presente estudo foi examinar a relação entre a suscetibilidade da cárie dentária e o polimorfismo dos genes AMELX e ENAMEM. Métodos: Foi coletado o DNA de 63 crianças em tratamento ortodôntico entre 8 e 12 anos de idade a partir das células da mucosa bucal. A genotipagem dos indivíduos quanto aos genes AMELX (rs 17878486) e ENAMEN (rs7671281) foi realizada por meio da reação em cadeia da polimerase (PCR) em tempo real. Adicionalmente, a presença de lesões cariosas foi analisada através de fotografias da documentação ortodôntica e análise radiográfica. Resultados: Neste estudo os resultados mostram que não há associação entre suscetibilidade a cárie dentária e o polimorfismo do gene AMELX. Porém, foi observada uma associação entre a frequência genotípica do gene ENAMEN e a cárie dentária. 33% da crianças portadoras do genótipo CT apresentaram cárie, enquanto 93,9% daquelas que tinham o genótipo TT não apresentaram a doença. Há a hipótese de que o genótipo CT codifica a proteína enamelina alterada, alterando a formação do esmalte e aumentando a suscetibilidade do hospedeiro à cárie. Conclusões: O genótipo CT para o gene ENAMEN pode ser considerado como um fator de risco à cárie dentária. Agência de Fomento: FUNADESP

Analysis of the reproducibility of the gray values and noise of a direct digital radiography system

The aim of this study was to evaluate the reproducibility of the gray values and noise of a direct digital radiography system (Visualix eHD) for various exposure times and analyzed regions. To obtain radiographic images in a standardized manner, the digital sensor of the system and a stepwedge were positioned in a phantom at a focus-film distance of 30 cm in a dental device at 70 kV, 7 mA and 2.2 mm filtration. Ten consecutive repetitions of X-ray imaging were performed at each exposure time (0.05, 0.07, 0.09 and 0.13 s). Gray values were analyzed using ImageJ software in five regions of interest (ROIs): alveolar bone (AB), soft tissue (ST) and three steps of the stepwedge (S1, S2 and S3). The results showed that both the variability of the gray values and the noise were statistically greater (p < 0.05) in the most radiolucent region (ST). Only the noise was affected by the exposure time. In conclusion, the reproducibility of the gray values and the noise of the Visualix eHD system can vary in specific areas with different radiolucency.

Mandibular Atrophy and Genial Spines Enlargement on Cone Beam Computed Tomography

Purpose. The aim of this paper is to report a case in which the cone beam computed tomography (CBCT) was important for the confirmation of the presence of mandibular atrophy and genial spines enlargement. Case Description. A 76-year-old female patient was referred for the assessment due to the complaint of chronic trauma in the anterior region of the floor of the mouth, which had been present for 2 months. CBCT images showed severe resorption of alveolar ridge and genial spines enlargement (5.5 mm × 12 mm). Conclusion. Accurate imaging assessment with the aid of 3D reconstructions allows the elimination of image superimposition and, therefore, plays an important role in the depiction of anatomical and pathological conditions, such as genial spines enlargement.