Evaluation of the maxillary premolar roots dissociation using radiographic holders with conventional and digital radiography

This in vivo study evaluated the dissociation quality of maxillary premolar roots combining variations of vertical and horizontal angulations by using X-ray holders (Rinn -XCP), and made a comparison between two types of intraoral radiography systems - conventional film (Kodak Insight, Rochester, USA) and digital radiography (Kodak RVG 6100, Kodak, Rochester, USA). The study sample was comprised of 20 patients with a total of 20 maxillary premolars that were radiographed, using the paralleling angle technique (GP), with a 20º variation of the horizontal angle (GM) and 25º variation of the horizontal angle combined with 15º vertical angle (GMV). Each image was independently analyzed by two experienced examiners. These examiners assigned a score to the diagnostic capability of root dissociation and the measurement of the distance between the apexes. Statistical data was derived using the Wilcoxon Signed Rank test, Friedman and T test. The means of the measured distances between buccal and lingual root apexes were greater for the GMV, which ranged from 2.3 mm to 3.3 mm. A statistically significant difference was found between GM and GMV when compared to GP with p < 0.01. An established best diagnostic dissociation roots image was found in the GMV. These results support the use of the anterior X-ray holders which offer a better combined deviation (GMV) to dissociate maxillary premolar roots in both radiography systems

Ex vivo analysis of apical human tooth in 3D sections using computed micro-CT

O objetivo deste estudo in vivo foi investigar as imagens obtidas por microtomografia computadorizada (micro-TC) no estudo da anatomia apical de dentes humanos portadores de polpa viva e mortificada. Trinta e cinco dentes humanos unirradiculares ou multirradiculares que tiveram suas raízes separadas totalizando quarenta e uma raízes foram rigorosamente pré-selecionadas e divididas em dois grupos: com polpa viva (PV) n = 21 e com polpa mortificada (PM) n = 20. Os dentes de ambos os grupos foram escaneados pelo sistema de microtomografia computadorizada (SkyScan 1172) com resolução de 6,7m e suas imagens reconstruídas para a análise da região apical nos cortes sagital e coronal. O diâmetro do forame apical (FA) e da junção cemento-dentina (JCD) foram medidos bem como suas distâncias (extensão do cemento) em ambos os lados da raiz. Posteriormente a coroa dos dentes foi cortada no seu colo anatômico e suas raízes foram medidas com paquímetro eletrônico e a odontometria realizada com localizador eletrônico apical (RomiApex A15). A subtração desses dois dados foi correlacionada com as medidas obtidas pela micro-TC na avaliação da posição da JCD. As raízes foram preparadas para avaliação histológica em cortes longitudinais de 6m de espessura e corados com HE. Os cortes que apresentaram a emergência do FA foram fotografados digitalmente e as imagens correspondentes de micro-TC foram sobrepostas com o intuito de ilustrar a metodologia utilizada. As medidas da micro-TC foram realizadas por dois examinadores devidamente instruídos. A concordância inter-examinadores foi confirmada pelo coeficiente de correlação intraclasse (ICC) e as medidas foram comparadas pelo teste de Mann-Whitney (teste de Wilcoxon rank sum - p0,05). Os resultados indicaram que não houve diferença estatisticamente significante quanto à extensão do cemento intrarradicular nos grupos quer de polpa viva como mortificada com distâncias de 0,32±0,1mm e 0,36±0,16mm respectivamente. As medidas realizadas pelo localizador apical, a 1,0mm aquém, garantiu o estabelecimento do limite dentro do canal dentinário. Os resultados encontrados para o diâmetro do forame apical foi 619,32±32 m para o grupo PV e 630,542±140,99m para o grupo PM sem diferença estatisticamente significante. O diâmetro do canal radicular na junção cemento-dentina não apresentou diferença estatisticamente significante entre PV com 330,37±126,62m e PM com 357,62±996,14m. O posicionamento da JCD em relação ao FM não foi influenciado pelo estado de vitalidade pulpar.This ex vivo study aimed to investigate the apical anatomy of vital and necrotic human roots by microcomputed tomography (micro-CT). Thirty-five single or multirooted human teeth that had their roots separated totaling forty-one roots were carefully pre-selected and divided into two groups: vital pulp (VP) n = 21 and necrotic pulp (NP) n = 20. Both groups were scanned by microcomputed tomography system (SkyScan 1172) with 6.7m resolution and the apical region was analyzed by reconstructed images in sagittal and coronal sections. The diameters of the apical foramen (AF) and root canal at the cemento-dentino canal junction (CDJ) were measured. The cementum extension into the root canal was measured on both sides of the root canal. Thereafter the teeth crown was cut at the cemento-enamel junction, the length of roots was measured with a caliper and the working length was performed by an electronic apex locator (RomiApex A15). The result of the subtraction of these two data was correlated with measures obtained by micro-CT in the evaluation of CDJ position. The roots were sectioned in longitudinal histological sections of 6m thickness and stained with HE. The sections that showed the emergence of the FA were digitally photographed and the corresponding micro-CT sections were correlated by superimposition in order to illustrate the methodology. Measures of micro-CT scans were performed by two calibrated examiners. The interexaminers agreement was confirmed by intraclass correlation coefficient (ICC) and measurements were compared by Mann-Whitney test (Wilcoxon rank sum test - p0.05). The results indicated that there was no statistically significant difference in relation to the extension of cementum into the root canal in both goups VP or NP with average distances of 0.32±0.1mm and 0.36±0.16mm respectively. The measurements taken by the apex locator 1 mm from the apex were within the limits of dentinal canal. The diameter of the apical foramen corresponded to the NP group was 619.32±201.61m and 619.32±140.99m on average, not statistically significant. The average diameter of the root at the CDJ was 330.37±126.62m for VP and 357.62 ±96.14m for NP groups presenting no statistically significant difference. The distance of the CDJ in relation to AF was not influenced by the pulp vitality

Micro-CT assessment of two different endodontic preparation systems

The aim of this study was to compare two endodontic preparation systems using micro-CT analysis. Twenty-four one-rooted mandibular premolars were selected and randomly assigned to two groups. The samples (n = 12) of Group 1 were prepared using the ProTaper Universal rotary system, while Group 2 (n = 12) was prepared using the EndoEZE AET system complemented by manual apical preparation with K-type hand files up to #30. A 2.5% sodium hypochlorite solution was used in both groups for irrigating. Both groups were scanned by highresolution microcomputed tomography before and after preparation (SkyScan 1172, SkyScan, Kontich, Belgium). The root canal volume and surface area was measured before and after preparation, and the differences were calculated and analyzed for statistically significant differences using ANOVA complemented by the Tukey test (p < 0.05). The results showed no statistically significant differences between the mean volumes of dentin removal by the two systems. However, the EndoEZE AET system presented a significantly greater mean surface area compared to the ProTaper system (p < 0.05). The EndoEZE AET system enabled preparation of a greater root canal surface area when compared to the ProTaper Universal system. There seemed to be no difference in dentin volume loss between the two systems used