No abstract

The aim of the present study is to compare different analytical methods for singlet oxygen and to discuss an appropriate way to evaluate the yield of singlet oxygen photogenerated from photosensitizers. Singlet oxygen photogenerated from rose bengal was evaluated by electron spin resonance analysis using sterically hindered amines, spectrophotometric analysis of 1,3-diphenylisobenzofuran oxidation, and analysis of fluorescent probe (Singlet Oxygen Sensor Green®). All of the analytical methods could evaluate the relative yield of singlet oxygen. The sensitivity of the analytical methods was 1,3-diphenylisobenzofuran < electron spin resonance < Singlet Oxygen Sensor Green®. However, Singlet Oxygen Sensor Green® could be used only when the concentration of rose bengal was very low (<1 µM). In addition, since the absorption spectra of 1,3-diphenylisobenzofuran is considerably changed by irradiation of 405 nm laser, photosensitizers which are excited by light with a wavelength of around 400 nm such as hematoporphyrin cannot be used in the 1,3-diphenylisobenzofuran oxidation method. On the other hand, electron spin resonance analysis using a sterically hindered amine, especially 2,2,6,6-tetramethyl-4-piperidinol and 2,2,5,5-tetramethyl-3-pyrroline-3-carboxamide, had proper sensitivity and wide detectable range for the yield of photogenerated singlet oxygen. Therefore, in photodynamic therapy, it is suggested that the relative yield of singlet oxygen generated by various photosensitizers can be evaluated properly by electron spin resonance analysis.

Human subjects commonly show large variations in bite force produced at the first molar teeth. To evaluate the role of muscle cross-sectional sizes and lever arms in bite-force production, we correlated these variables in 11 healthy adults. Axial and coronal images obtained by magnetic resonance were combined with conventional lateral cephalograms and dental cast data to reconstruct the craniomandibular morphology in each subject. The cross-sectional sizes of the right masseter and medial pterygoid muscles, their lever arms, and the bite-point lever arms were measured directly from these reconstructions. Physiological recordings of bite force were made in the region of the right first molar by means of a customized transducer aligned perpendicular to the functional occlusal plane. The average bite force for the sample as a whole was 189 +/- 78 N. The coefficients of variance were greater for bite forces, and for the cross-sectional sizes of the two muscles, than for their respective lever arms. Highly significant Pearson Product Moment correlation coefficients (p less than 0.005) were found between masseter and medial pterygoid cross-sectional size, and between the cross-sectional size of each muscle and bite force. No significant correlations (p greater than 0.1) were found between muscle or bite-point lever arms and bite force. Despite the fact that craniofacial spatial morphology may differ among subjects, jaw muscle size alone seems to explain most of the variation in bite force reported by ourselves and others.

The aim of this study was to investigate the correlation between the masticatory function and the maxillary defect configuration, size, and remaining teeth in post-maxillectomy patients restored with an obturator prosthesis. Fifty consecutive post-maxillectomy patients (mean age 67.0) participated in this study. The subjects consisted of 26 dentate and 24 edentulous patients. Data were collected from the patients' clinical records, diagnostic casts, and a questionnaire on masticatory function to evaluate the defect configuration, size, and the masticatory function scores associated with wearing obturator prostheses. The defect size was evaluated by the ratio of defect area to the horizontal impression area. The defect configuration was assessed according to Aramany's classification and separated into unilateral and bilateral defects. The multiple regression analysis and the Mann-Whitney U-test (P<0.05) were used to assess statistical significance. The Spearman's correlation coefficient by rank test was also used to detect correlation. The following conclusions were made: (i) The presence of teeth in the maxillary dentition and the different type of the defect configuration had significant correlation with the masticatory function score (r=0.616). (ii) The masticatory function scores of the subjects differed significantly with the presence of teeth in the maxillary dentition and the different types of defect configurations (P=0.005, P=0.002, respectively). (iii) There was significant correlation between the masticatory function score and the size of the defect area in the edentulous group (r=-0.648, P=0.001). The presence of teeth, the size and configuration of the defect influenced the masticatory function of post-maxillectomy patients with obturator prostheses.

The calcium phosphate-based TMD and GLU proved highly effective in reducing sensitivity.