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The reactions of 2,3‐dimethyl‐ (4), 2,3‐diphenyl‐ (6), and 2‐methyl‐3‐phenyl‐pyrazine monoxides (8 and 9) with phosphoryl chloride and acetic anhydride resulted in giving monochloro‐ and monacetoxy‐pyrazines in almost all cases. However, the reaction of 6 with acetic anhydride afforded exceptionally a diacetoxydihydro‐pyrazine. These products were converted further to hydroxy or dichloro derivatives.

The purpose of this study was to investigate the fluctuation of gingival crevicular pH during experimentally evoked gingivitis and occlusal trauma, and to examine the relationship between the pH and periodontal health status using a newly developed pH sensor. Maxillary first premolars with clinically healthy gingiva were selected as test teeth in 10 volunteers. In the first study phase, experimental gingivitis was evoked, and gingival index, plaque index, and crevicular pH were recorded during the study period. In the second study phase, experimental occlusal trauma was created with metal onlays having occlusal interferences in lateral movements, and tooth mobility and pH were recorded during the study period. In the gingivitis phase, Gl, P1I, and pH values fluctuated significantly during the study period (P < 0.01) and positive correlations were observed between both GI and pH values (P < 0.05), and P1I and pH values (P < 0.01). In the occlusal trauma phase, significant fluctuation was found among tooth mobilities (P < 0.05) during the study phase, but not in pH values. Statistically significant correlations were not observed between tooth mobilities and pH values. These data suggest that the crevicular pH level may not be influenced by experimental occlusal trauma, but shifts toward alkaline with experimental gingivitis. J Periodontol 1998;69:1036–1043.

: An occlusal diagnostic system was evaluated for clinical applications.This system consists of pressure sensitive sheets (DENTAL PRESCALE (R), Fuji Photo Film Co.) and the analyzing computer (OCCLUZER FPD 703 (R), Fuji Photo Film Co.). Effects of velocity and duration of pressure and temperature upon color forming of pressure sensitive sheets were examined. While simulating intraoral applications, the accuracy of this system was examined using maxillary and mandibular casts.The results were as follows:1. There was no effect velocity of pressure and temperature upon color forming.2. There was no statistical difference in color forming between the sheets pressed of one second and five seconds. But the sheets pressed for ten seconds showed higher color forming than the sheets pressed for one second.3. When the forces measured by this system were subtracted from the load on the maxillary and mandibular casts, the mean values of the remainders were -0.68 kgf (Type-R, 30H) and -0 .65 kgf (Type-R, 50H). The standard deviations were 1.57 kgf (30H) and 1.09 kgf (50H).