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Objective: For dental students, textbooks and lectures provide basic knowledge, and simulated and actual clinical training provide learning in technical and communication skills. At our college, conservative dentistry is taught in the third and fourth years of a 6‐year undergraduate degree. Clinical training is undertaken subsequently in the fifth year and includes cavity preparation and composite resin filling tasks. However, despite the clinical importance of a full understanding surrounding these procedures, sixth‐year students occasionally provide incorrect answers regarding these procedures in assessments. Although they demonstrated a basic understanding of the procedures, they may have forgotten the acquired knowledge during their clinical training. Therefore, we developed an error‐detection examination to evaluate and improve fifth‐year students' knowledge. Methods: Written detailed treatment procedures for standardized, typical, cases were presented to students. Some critical steps were intentionally written incorrectly, and students had to identify and correct these. After correcting the steps, students gave a presentation to their peers on their corrections. This was followed by a summary of the correct answers and a short lecture by the teacher. Students then completed a questionnaire investigating their experience of the examination. Results: Students misunderstood some key treatment steps, such as pretreatment of composite resin filling, amalgam removal, and ceramic inlay fitting. The questionnaire revealed that this method of testing applied knowledge was new to students and helped them to identify knowledge gaps. The test also increased their motivation to study conservative dentistry. Students were open to taking similar tests in different areas. Conclusion: Although conservative dentistry is a basic field of dental treatment, mistakes in treatment can lead to early treatment failure or reduce the lifetime of a restored tooth. Therefore, students need to have a deep understanding of procedures. Error‐detection examinations may help students identify knowledge gaps and provide useful feedback to teachers to identify areas that they should stress in earlier years. [ABSTRACT FROM AUTHOR]

Biporous (macro- and microporous) calcium phosphate gains much attention as a bone substitute material because of its large surface area and that it improves cell penetration In the present study, we evaluated the feasibility of biporous, low-crystalline apatite hosed on dissolution of mannitol from self setting apatite cement (Biopex®). Mannitol known as a biocompatible, easily dissolved monosaccharide alcohol -- was recrystallized to obtain larger crystals. It was crushed with pestle and mortar, sieved to obtain crystals which passed through a 500-µm mesh but which remained against a 300-µm mesh, and then used as porogen. Although Biopex® containing 60 wt% mannitol was not able to be taken out of the mold, addition of mannitol caused no initial setting inhibition to Biopex® if the amount was 40 wt% or less. Similarly, transformation to apatitic product was confirmed when the apatite cement was immersed in 0.9% saline kept at 37°C for seven days The set mass became low crystalline, hiporous apatite with approximately 60% porosity. [ABSTRACT FROM AUTHOR]

The material concept of resin cements capable of disintegrating due to near-infrared (NIR) radiation was verified. The cements were prepared by adding silicon carbide (SiC), which heats upon absorbing NIR rays, and thermally expandable particles (TEPs) to 4-META/MMA-TBB resin cement. The microtensile bond strength (µTBS) and cytocompatibility of the cements were evaluated. The resin cements with 5 mass% SiC and 20-40 mass% TEPs had significantly lower µTBS after NIR radiation than before NIR radiation, and their cytocompatibility was not decreased by SiC and TEPs additions. Furthermore, in vitro thermal damage tests were performed using the resin cement with 5 mass% SiC and 20 mass% TEPs, a typical composition. The results demonstrated conditions that significantly reduced µTBS and minimized thermal damage by NIR radiation. Although these data are only proof of concept, the possibility that dental devices bonded with these cements could be detached by NIR radiation was demonstrated.

Carbonate apatite (CO3Ap), fabricated by dissolution-precipitation reaction based on an appropriate precursor, is expected to be replaced by bone according to bone remodeling cycle. One of the precursor candidates is gypsum because it shows self-setting ability, which then enables it to be shaped and molded. The aim of this study, therefore, was to fabricate CO3Ap blocks from set gypsum. Set gypsum was immersed in a mixed solution of 0.4 mol/L disodium hydrogen phosphate (Na2HPO4) and 0.4 mol/L sodium hydrogen carbonate (NaHCO3) at 80-200°C for 6-48 h. Powder X-ray diffraction patterns and Fourier transform infrared spectra showed that CO3Ap block was fabricated by dissolution-precipitation reaction in Na2HPO4-NaHCO3 solution using set gypsum in 48 h when the temperature was 100°C or higher. Conversion rate to CO3Ap increased with treatment temperature. CO3Ap block containing a larger amount of carbonate was obtained when treated at lower temperature.

Effects of sintering temperature on the physical and compositional properties of alpha-TCP foam fabricated using the polyurethane foam method were examined. When a polyurethane foam coated with alpha-TCP slurry was sintered at 1,400-1,550 degrees C, alpha-TCP foam having basically the same fully interconnected porous structure was produced although shrinkage occurred with increasing sintering temperature. On porosity of the alpha-TCP foam, a higher foam porosity of 95% was obtained when sintered at 1,400 degrees C as compared to the 90% porosity obtained at a higher sintering temperature of 1,550 degrees C. Further, at 1,500 degrees C or higher temperature, frame became dense with disappearance of micropores. On compressive strength, it increased from approximately 50 to 250 kPa when sintering temperature was increased from 1,400 to 1,550 degrees C. Nonetheless, no compositional changes were observed even when the alpha-TCP foam was cooled in the furnace without quenching process. In light of the results obtained, it was concluded that alpha-TCP foam fabricated using the polyurethane method was useful as a bone substitute and/or scaffolding material for tissue engineering. Besides, alpha-TCP foam could be useful as a precursor for the fabrication of other calcium phosphate foams.