Abstract : Intraoral cameras enable greater accuracy in medical examination, diagnosis, and treatment. The objective of this study was to examine the effects of illumination components of intraoral cameras (i.e., relationship between the optical axis and photographing axis) on generated images.

 An intraoral camera comprising two optical axes for illumination (Penviewer, Morita) was used for the test. A root canal model with the pulp chamber open (A12-500, Nissin) was photographed to obtain a picture of the pulp chamber, starting from the occlusal surface, in parallel with the tooth axis. Two different photography conditions were studied—coaxial mode, in which the optical axis coincides with the photographing axis, and white mode, in which not only one tooth but also the entire intraoral area can be photographed. The images taken were evaluated on a 5-point scale and statistical analysis (p<0.05) was performed for each condition.

 All of the images taken showed the root canal orifice. The images taken in coaxial mode were significantly better than those in white mode (p<0.05). These results show that coaxial mode is more suitable for intraoral observation than white mode.

Abstract : The purpose of this study was to examine the characterization of fractured surfaces of two types of nickel-titanium (NiTi) file, M-Wire [WaveOne (WO)] and NiTi alloy in the R-phase of crystalline structure [Twisted File (TF)], by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Twelve fractured and one unused files of WO and 11 fractured and one unused files of TF were used in this study. Six WO and four TF fractured files were examined by XRD and the remainder were observed by SEM. The results of WO by XRD revealed a sharp and high peak around 42 degrees and a mild peak around 78 degrees at the fractured surfaces. The results of TF by XRD showed a sharp but broad peak around 42 degrees and a small peak around 78 degrees at the fractured surfaces. The results by SEM showed a mixture of smooth and rough areas for WO and skewed dimples near the center of rotation for TF. The results of this study showed that the phases of WO and TF were changed after fracture and the morphological characteristics of WO after fracture were different from those of TF.

Abstract : Water-extract solutions of the surface reaction type pre-reacted glass-ionomer (S-PRG) filler forms precipitate when mixed with artificial saliva, suggesting their application as dentin desensitizers. This study investigated the dentinal tubule occlusion and elemental incorporation when ground human dentin was treated with S-PRG filler extract solutions followed by artificial saliva. Human ground dentin specimens were coated with SF0 (an S-PRG filler extract solution without filler particles) or SF50 (an S-PRG filler slurry containing 50% of filler particles) for 30 seconds and then immersed in artificial saliva for 7 and 28 days. The surface of the specimens was analyzed by scanning electron microscopy (SEM) and wavelength-dispersed electron probe microanalysis (EPMA). The SEM analysis revealed that both SF0 and SF50 induced the formation of insoluble deposits on the tubule openings and peritubular area. The deposits were most prominent after 28 days of immersion of the SF50-applied specimens. EPMA detected fluoride- and strontium-rich areas on the dentin surface. It was concluded that the two-step treatment (S-PRG filler extracts followed by artificial saliva) of ground human dentin induced dentinal tubule occlusion and uptake of fluoride and strontium, suggesting that the treatment may be effective in controlling dentin hypersensitivity.

Abstract : The odd-skipped related (Osr) gene is a zinc-finger transcription factor that is involved in embryonic development and bone formation. The aim of this study was to evaluate the role of Osr2 in odonto/osteoblastic differentiation of mouse dental papilla cells (MDPs). Osr2 mRNA expression in the dental pulp tissues of upper and lower incisors and gingival tissues was examined using C57BL/6 mice. MDPs were cultured in α-modified minimum essential medium containing 10% fetal bovine serum and antibiotics. The Osr2 expression vector was transfected into MDPs, and a stable cell line was selected. Relatively high expression of Osr2 was detected in the dental pulp tissues compared to gingival tissues. Enhanced expression of Osr2 in MDPs promoted the expression of odonto/osteoblastic genes and nodule formation. These results suggested the involvement of Osr2 in the odonto/osteoblastic differentiation of MDPs/dental pulp cells, which may occur in the mature dental pulp tissues.