Purpose: Several hydrophilic and hydrophobic approaches have been developed to prevent food debris and plaque accumulation on the denture surface. In this study, we evaluated the possibility of developing a high-functioning self-cleaning denture.Materials and Methods: Denture base resin specimens were divided into the following groups based on the type of surface treatment: control (no treatment); hydrophilic (UV irradiation or tribochemical coating); and hydrophobic (plasma chemical vapor deposition, CVD). Surface analyses were conducted using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and atomic force microscopy. Physical strength was evaluated using the three point bending test. Data were analyzed using one-way analysis of variance followed by multiple comparisons.Results: The self-cleaning effects of the hydrophilic treatments were unsatisfactory; alternatively, the hydrophobicity, mechanical properties, and self-cleansing ability of the CVD specimens were significantly high (p < 0.05).Conclusion: Hydrophobic surface modifications effectively improved the water repelling properties of the resin without compromising its mechanical properties.

Purpose: This study aimed to examine root canal irrigant activation using a computer-controlled hot tip (thermo-optically powered [TOP] tip) heated with a 980 nm diode laser system (Alta Modular Laser System), with regard to vaporized bubble formation and soft tissue dissolution capacity.Materials and Methods: As a parameter of cleaning efficacy, the number and size of vaporized bubbles generated in root canal models during TOP tip-induced activation were analyzed with high-speed digital video imaging. To evaluate the soft tissue-dissolving efficacy of TOP tip-induced activation with a sodium hypochlorite irrigant, dissolution of porcine soft tissues filled in lateral canals set at two levels in root canal models were morphometrically analyzed. Irrigant temperature during TOP tip-induced activation was measured with thermocouples attached to the apical foramen and the lateral canals of root canal models.Results: High-speed video imaging revealed that TOP tip-induced activation of the water that filled the root canal models, required less time to achieve the first bubble formation and generated a larger number of bubbles than a normal clear tip-induced activation using the same laser. NaOCl solution activated with TOP tip dissolved more soft tissues filled in lateral canals of the canal models, than with passive ultrasonic irrigation and syringe irrigation. Irrigant temperature during TOP tip-induced activation showed a maximum increase of approximately 50˚C near the lateral canal, as measured with thermocouples.Conclusion: Under the present experimental conditions, TOP tip-induced irrigant activation exerted better cleaning efficacy-related properties than the other methods tested.

Purpose: The objective of this study was to investigate inhibitory effect of lactic acid bacteria and antibiotics on the growth of Streptococcus pneumoniae ATCC 33400.Materials and Methods: Antibiotic activities of five oral probiotic candidate bacteria including two strains of Lactobacillus crispatus, Lactobacillus fermentum, Lactobacillus gasseri and Streptococcus mitis and several antibiotics against S. pneumoniae were investigated using radial diffusion assay and competition assay. The biofilm formation of S. pneumoniae in the presence of 50% saturated ammonium sulfate precipitation fraction from L. gasseri and several concentrations of gentamicin were monitored by real time cell analyzer, xCELLigence. Results: The growth of S. pneumoniae was inhibited by two strains of Lactobacillus crispatus, Lactobacillus fermentum and Lactobacillus gasseri. The saturated ammonium sulfate precipitation fraction (0-30% and 30-50%) from L. gasseri effectively inhibited growth of S. pneumoniae. The biofilm formation of S. pneumoniae monitored by real time cell analyzer (xCELLigence) was suppressed by gentamicin in dose dependent manner. Antibacterial substance from L. gasseri against S. pneumoniae was suggested to be small molecular weight substance.Conclusion: L. gasseri inhibited the growth of S. pneumoniae suggesting that L. gasseri will be a candidate of probiotics.

Purpose: The purpose of this project is to compare the dental services by national hospital of three areas in Chin state, Myanmar.Materials and Methods: Demographic statistics were collected form Township health profile of every township stocked in municipal office. Number of patients who attended at the dental clinic within four national hospitals was summarized by month and year. The diagnosis and contents of treatment were summarized by year. In addition, fluoride concentration of tap water was measured. Results: Number of the patients who visited for the national hospital is fluctuated by month because of the school dental health checkups and landslide that prevent the people in local area to the national hospital. The most of the dental disease diagnosed were dental caries and pulpitis. More than seventy percent of the treatment was filling and extraction.Conclusion: The primary health care is not sufficient in Chin sate. In addition, health promotion is important especially health education. To promote these concepts, there still existed many obstacles in Chin state in Myanmar.

Purpose: The objective of this study was to evaluate the effect of low output power irradiation of erbium-doped yttrium aluminum garnet (Er:YAG) laser on surface morphology, roughness, and microhardness of the root dentin.Materials and Methods: Flat root dentin surfaces were prepared from extracted human molars. The surfaces were irradiated by an Er:YAG laser at 10 pps, 30 mJ, sweeping at approximately 2 mm/s by hand. Irradiated power was changed by means of the distance between laser tip and surface kept at 0, 5, 10, 15, 20, 25, 30, 35, and 40 mm. No irradiated surface was employed as control. Those surfaces and crosscut surfaces were observed by a scanning electron microscope (SEM). Specimens of irradiation distance at 0, 5, 10, 20, 30, and 40 mm and control (no irradiation) were further prepared and then, surface roughness (Ra) and microhardness (Vickers hardness) were measured.Results: Ablation of dentin was observed at distance between 0-15 mm. At 20-30 mm, degenerated layer was observed without ablation. At 35 and 40 mm, ablation and degenerated layer were not found. Ra values of all experimental groups (0-40 mm) showed statistically higher than that of control group (p < 0.05). Among the experimental groups, 0 mm group showed statistically higher Ra values than the other groups (p < 0.05). For Vickers hardness, no significant difference was found all groups except 0 mm group (p > 0.05).Conclusion: It was concluded that specific low output power Er:YAG laser irradiation produced thin degenerated layer on the root dentin without ablation. This irradiated surfaces showed slight increase of roughness without decrease of microhardness.

Purpose: This study aimed to evaluate the effects of 60 Gy γ-ray irradiation on the adaptation of resin composite restorations using two-step and one-step self-etching systems.Materials and Methods: One-half of bovine incisors were irradiated with 60 Gy γ-ray. Flat dentin surfaces were prepared on labial side. Cylindrical cavities were prepared on flat dentin surfaces. Cavities were restored with a two-step self-etching system Clearfil SE Bond or a one-step self-etching system Clearfil tri-S Bond adhesive, followed by Clearfil AP-X composite. The composites were light-cured with 600 mW/cm2 for 40 s. One-half of the specimens were thermocycled for 5,000 cycles. Dye penetration tests around the restorations were performed.Results: Irradiation with 60 Gy γ-ray significantly decreased resin composite adaptation for the non- thermocycled Clearfil SE Bond (p < 0.05). Clearfil tri-S Bond showed significantly decreased cavity wall adaptation compared with Clearfil SE Bond, regardless of the number of thermal cycling and γ-ray irradiation (p < 0.05). Irradiation with 60 Gy γ-ray significantly decreased nanohardness and elastic modulus of the dentin (p < 0.05).Conclusion: Irradiation with 60 Gy γ-ray significantly decreased resin composite adaptation for the non-thermocycled Clearfil SE bond. Further, nanohardness and elastic modulus of the dentin significantly decreased after the irradiation.

Purpose: Dental treatment is a stressful event. The aim of this study was to evaluate the feasibility of electroencephalography (EEG) for the measurement of stress the stress of the patient’s ongoing dental treatment.Materials and Methods: Real-time brain activity was measured for five healthy subjects (three males and two females) under contentious opening mouth conditions and compared with the relaxed conditions for 18 minutes. Brain activities were measured under the conditions that subjects were sited on the dental chair in horizontal situation. Electroencephalograph (EEG) were used to measure the five type of brain waves: θ, α1, α2, α3, and β. Results: In θ wave, α3 wave and β wave, widening gap between opening mouth condition and closing mouth conditions were observed with over the time course. This tendency was confirmed by autoregressive moving average (ARMA) model and mixed effect modeling. All of the coefficients of opening mouths were statistically significant, when closing mouth used as reference. EEG may be useful tool to measure the stress during dental treatment. Stress by sitting on dental chair in horizontal situation was depended on personality traits.Conclusion: Contentious opening mouth may be stressful; however, the amount of stress may be small. The changes can be seen within 18 min. Prolonged chair time for the dental treatment may not be recommended.