Background/purpose Glass ionomers undergo degradation when exposed to fluoride, which changes the physico-chemical characteristics of the materials. The purpose of this study was to evaluate the surface changes of resin-modified glass ionomer (RMGI) when immersed in a sodium fluoride (NaF) solution according to pH and time. Materials and methods 120 RMGI specimens were prepared, and 30 specimens were placed in four types of storage solutions for four weeks; pH 7 artificial saliva with or without 0.2% NaF (As7 and NaF7), pH 5 artificial saliva with or without 0.2% NaF (As5 and NaF5). Interferometry and microscopy were performed to evaluate the surface roughness and topography, while spectroscopy was used to analyze the chemical composition changes. Results Rougher topography and increased roughness was exhibited in NaF groups, owing to the disintegration of the polysalt matrix. Reduced Sr and F was exhibited in all groups, whereas NaF group showed a decrease in Al and inorganic components. Conclusion This study suggest that excessive use of fluoride therapy could lead to severe degradation of RMGI.

The purpose of this study is to evaluate the validity of primary anterior zirconia crown made with Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) technology by analyzing fracture strength and translucency parameter.<br/>Zirconia crown was designed with CAD software, using 3D scanned data of #61 tooth model. Crown fabrication was performed with CAM machine using zirconia block. Zirconia crowns were divided into 3 groups according to thickness(0.3, 0.5, and 0.7 mm), and fracture strength was compared with 1.0 mm thickness of resin strip crown. The compressive force was applied with universal testing machine at 30° along the incisal edge at increments of 1 mm/min. For translucency evaluation, 0.3, 0.5, and 0.7 mm thickness of zirconia specimens were fabricated and translucency was measured with spectrophotometer.<br/>Among zirconia groups, there was a significant increase in fracture strength as thickness increased (<i>p</i> < 0.05). The fracture strength of zirconia crown was significantly higher than resin strip crown in all groups (<i>p</i> < 0.05). Translucency parameter was highest in 0.3 mm group, and significantly decreased as thickness increased to 0.5 and 0.7 mm (<i>p</i> < 0.05).<br/>Thin primary anterior zirconia crown can be designed and fabricated according to individual needs by using CAD/CAM. Restoration with thin crown would reduce the amount of tooth reduction, risk of pulp exposure, and make more esthetic restoration possible.

The aim of this study is to compare cariogenic characteristics of fluoride-sensitive <i>Streptococcus mutans</i> [fluoride-sensitive (FS) <i>S. mutans</i> ] and fluoride-resistant <i>Streptococcus mutans</i> [fluoride-resistant (FR) <i>S. mutans</i>] in the presence of sucrose, and to evaluate its effect on cariogenic biofilm formation. <i>S. mutans</i> ATCC 25175 was continuously cultured in trypticase soy broth (TSB) containing NaF (70 ppm) for 40 days to generate FR <i>S. mutans</i> . FS and FR <i>S. mutans</i> were inoculated in TSB with or without 2% sucrose, and optical density and pH were measured every hour. An oral biofilm was formed using saliva bacteria and analyzed through confocal laser scanning microscopy and CFU count. Finally, the expression of glucosyltransferases genes of both <i>S. mutans</i> was investigated through RT-PCR. FR <i>S. mutans</i> exhibited slower growth and lower acidogenicity in the presence of sucrose compared to FS <i>S. mutans</i> . Both cariogenic and single species biofilm formation was lower in the presence of FR <i>S. mutans</i> , along with reduced number of bacteria. FR <i>S. mutans</i> showed significantly low levels of gtfB, gtfC, and gtfD expression compared to FS <i>S. mutans</i> . On the basis of results, FR <i>S. mutans</i> may be less virulent in the induction of dental caries.

Patient management is considered an important factor in dental field. The aim of this review is to analyze the efficacy of hypnosis to treat fear, anxiety, pain, stress of dental patients, and see how it can be adopted in dentistry for improving patient satisfaction. Medline research was carried out to find the use of hypnosis in dentistry and other aspects of hypnosis in medical area. It can help patient more comfortable, relax, and accordingly reduce patient's negative feelings such as fear, anxiety, pain, stress during dental treatment. Also, it affects patient recovery after surgery by accelerating healing speed and reinforce immune system. When hypnosis is used with other anesthetic method, it can reduce the use of main medication, leading to reduce possibility of side effect. Therefore, using Hypnosis can give patients more comfortable dental experience, both mentally and physically, ultimately making patients more satisfied with the dental treatment.