The initial adhesion of microorganisms to clinically used dental biomaterials is influ­ enced by physicochemical parameters, such as pre­adsorption of salivary proteins. The forma­ tion of biofilms begins with the adhesion of microorganisms. The presence of biofilms is thought to affect the ability of microorganisms to adsorb and accumulate on the surfaces of denture ma­ terials, facilitating bacterial adhesion and resulting in a greater risk of bacterial infiltration of the denture materials. Many common materials, such as polymers and metal alloys, are currently used in the manufacture of dentures. It is important to quantitatively investigate the adsorption of salivary proteins to denture materials. We fabricated highly stable denture materials as quartz crystal microbalance (QCM) sensors and evaluated the difference in the adsorption behavior to them of different types of bovine salivary proteins. PMMA and Ti QCM sensors were fabricated by spin­coating and sputtering onto bare QCM sensors. The amount of salivary­related protein on the PMMA QCM sensors was greater than those on the Ti and Au QCM sensors. We found that the PMMA and Ti QCM sensors are useful tools to study the adsorption and desorption of albumin and mutin on denture surfaces. Shika Igaku (J Osaka Odontol Soc) 2017 ;Septem­ ber ;80(2) : 55­-66.

Recently dental students have experienced considerable stress because of the in­ creasing difficulty of the Japanese National Dental Examination. We investigated how students handled this stress. The students in the sixth year at Osaka Dental University were given a questionnaire in 2015 with 36 items, including how they handled stress during their graduation examination. In this study with the results of the examination being a dependent variable, a sig­ nificant difference test was conducted between the pass group and the fail group for the 36 items. Of the 140 sixth year students, 73 passed. Significant differences were found between the two groups in 10 of the 36 questions. Discriminant analysis indicated that the factors of com­ prehension, coping and the avoidance strongly correlated with whether the student passed or failed. The correct answer rate by the linear discriminant function was 66.7% in the pass group. Shika Igaku (J Osaka Odontol Soc) 2017 ;September ;80(2) : 67­-73.

Antimicrobial protein secretion in the rat submandibular gland induced by aroma inhalation

Takayuki Izutani, Kenji Uchihashi and Yasuo Nishikawa (Dept. Physiology, Osaka Dental Univ.)

Application of aroma is likely to enhance antimicrobial action. We attempted to clarify whether aroma promotes anti­ bacterial protein secretion in saliva. We found no spontaneous secretion from the submandibular gland in the control rats. Altrhough aroma inhalation elicited successively increased secretory responses, it did not attain that achieved by isoprenaline stimulation. The salivary amylase activity induced by aroma inhalation was approximately 10％that of isoprenaline stimulation. Combined use of isoprenaline stimulation and aroma inhalation enhanced both SIgA and lac­ toferrin concentration compared with stimulation by isoprenaline alone. These results suggest that the use of aroma enhances salivary antibacterial activity, and that this activity may be induced by the sympathetic nervous system. We hypothesized that aromas might positively influence the intraoral environment.