Filling ability and flow of root canal sealers: a micro-computed tomographic study

Abstract This study evaluated by micro-computed tomography (μCT) the filling ability in curved root canals, besides the flow of AH Plus (AHP) and Neo MTA Plus (NMTAP) sealers using different methodologies. Mandibular molars mesial roots with two root canals and degree of curvature between 20° and 40° were selected. The specimens were prepared with the ProDesign R system up to size 35.05 and were filled with the sealers by a continuous wave of condensation technique, Thermo Pack II (n=12). The teeth were scanned using μCT after root canal preparation and obturation. The volumetric percentage of filling material and voids were calculated. Flow was evaluated based on ISO 6876/2012 (n=10). Flow and filling were also evaluated in μCT using a glass plate with a central cavity and four grooves from the central cavity (n=6). Flow was linearly calculated into the grooves. The central cavity filling (CCF) and lateral cavity filling (LCF) were calculated in mm³. Data were submitted to non-paired t test with a significance threshold at 5%. The percentage of filling and voids between the root canals filled with AHP or NMTAP was similar (p>0.05). NMTAP presented the lowest flow in conventional test (p<0.05). Using μCT, sealers had similar CCF, LCF and linear flow (p>0.05). In conclusion, NMTAP and AHP had similar filling ability in curved mesial root canals of mandibular molars without presence of isthmus. Although AHP presented better flow than NMTAP using ISO methodology, there was no difference between these materials regarding volumetric filling when evaluated by μCT.

Resumo Este estudo avaliou por microtomografia computadorizada (μCT) a capacidade de preenchimento de canais radiculares curvos, além do escoamento dos cimentos AH Plus (AHP) e Neo MTA Plus (NMTAP) utilizando diferentes metodologias. Foram selecionadas raízes mesiais de molares inferiores com dois canais radiculares e grau de curvatura entre 20° e 40°. As amostras foram preparadas com o sistema ProDesign R até o tamanho 35.05 e foram obturadas com os cimentos por uma técnica de onda contínua de condensação, Thermo Pack II (n=12). Os dentes foram escaneados usando μCT após o preparo e obturação do canal radicular. A porcentagem volumétrica de material de preenchimento e vazios foram calculados. O escoamento foi avaliado com base na norma ISO 6876/2012 (n=10). O escoamento e o preenchimento também foram avaliados em μCT usando uma placa de vidro com uma cavidade central e quatro canaletas a partir da cavidade central (n=6). O escoamento foi calculado linearmente nas canaletas. O preenchimento da cavidade central (PCC) e o preenchimento da cavidade lateral (PCL) foram calculados em mm³. Os dados foram submetidos ao teste t não pareado com nível de significância de 5%. A porcentagem de preenchimento e vazios entre os canais radiculares preenchidos com AHP ou NMTAP foi semelhante (p>0,05). NMTAP apresentou o menor escoamento no teste convencional (p<0,05). Utilizando μCT, os cimentos apresentaram PCC, PCL e escoamento linear semelhantes (p>0,05). Em conclusão, NMTAP e AHP apresentaram capacidade de preenchimento semelhante em canais mesiais curvos de molares inferiores sem presença de istmo. Embora o AHP tenha apresentado melhor escoamento que o NMTAP usando a metodologia ISO, não houve diferença entre esses materiais em relação ao preenchimento volumétrico quando avaliados por μCT.

Regulation of ghrelin receptor by microbial and inflammatory signals in human osteoblasts

Abstract: Recently, it has been suggested that the anti-inflammatory hormone ghrelin (GHRL) and its receptor GHS-R may play a pivotal role in periodontal health and diseases. However, their exact regulation and effects in periodontitis are not known. The aim of this in-vitro study was to investigate the effect of microbial and inflammatory insults on the GHS-R1a expression in human osteoblast-like cells. MG-63 cells were exposed to interleukin (IL)-1β and Fusobacterium nucleatum in the presence and absence of GHRL for up to 2 d. Subsequently, gene expressions of GHS-R1a, inflammatory mediators and matrix metalloproteinase were analyzed by real-time PCR. GHS-R protein synthesis and NF-κB p65 nuclear translocation were assessed by immunocytochemistry and immunofluorescence microscopy, respectively. IL-1β and F. nucleatum caused a significant upregulation of GHS-R1a expression and an increase in GHS-R1a protein. Pre-incubation with a MEK1/2 inhibitor diminished the IL-1β-induced GHS-R1a upregulation. IL-1β and F. nucleatum also enhanced the expressions of cyclooxygenase 2, CC-chemokine ligand 2, IL-6, IL-8, and matrix metalloproteinase 1, but these stimulatory effects were counteracted by GHRL. By contrast, the stimulatory actions of IL-1β and F. nucleatum on the GHS-R1a expression were further enhanced by GHRL. Our study provides original evidence that IL-1β and F. nucleatum regulate the GHS-R/GHRL system in osteoblast-like cells. Furthermore, we demonstrate for the first time that the proinflammatory and proteolytic actions of IL-1β and F. nucleatum on osteoblast-like cells are inhibited by GHRL. Our study suggests that microbial and inflammatory insults upregulate GHS-R1a, which may represent a protective negative feedback mechanism in human bone.