한국인에서 치아를 상실하는 원인의 46.4%는 치아우식증이고, 38.1%는 치주병이며, 치아우식증은 주로 국민학교 학령기에 발생되고, 치주병은 대개 국민학교 졸업기를 전후하여 발생되기 시작한다. 따라서 우리나라 국민의 구강건강기틀은 국민학교 학령기에 잡힌다고 할 수 있다. 그리고 학생은 학교라는 특수 집단사회에서 일반국민과는 다른 생태를 가지고 있다. 그러므로 국민건강을 합리적으로 발전시키기 위해서는 학교구강보건으로부터 개발해 나아가야 한다. 이러한 관점에서 학교구강보건에 관하여 검토해보도록 한다.

An experimental study was performed to study the tissue reactions to tissue conditioners in rabbits. Thirty rabbits were divided into three groups, 10, Hydro-cast group, 10, Coe-comfort group, and 10, heat-cured resin group. Tissue conditioners and heat-cured resin were embedded in the oral mucosa of rabbits. The tissue specimens were removed on 3rd, 7th, 14h, 21st and 28th day after embedding and examined under microscope after staining them with H-E stain, Van Gieson's stain, Masson's trichrome stain and PAS reaction. The results were as follows : 1. Tissue reactions to tissue conditioners were somewhat different from each other in the early stage, but, with the increase of the embedding period, the fibrous capsule was thickened in both. These tissue reactions were similar to those to heat-cured resin. 2. Newly formd fibrous components were stained deep-red with Van Gieson's stain and dark-green with Masson's trichrome stain. But their stainability was decreased as collagenous fibers became matured. 3. Newly formed fibrous components showed intense PAS reactivity, but PAS reactivity was reduced as the connective tissue capsule became completed.

A series of combined impressions, alginate impressions and rubber base impression made of the lower left quadrant of one subject having a cast gold crown with six reference marks on lower let 1st molar. the combined impressions of hydrocolloid were removed from the mouth at 2.5min, after the insertion of the tray. The alginate impressions were removed from the mouth at 2min, after the insertion of the tray. The rubber base impressions were removed from the mouth at 10min. The effect on the accuracy of the combined impressions, alginate impressions and rubber base impressions was obtained following results by comparing the distances between the reference marks in indirect stone cast with the standard measurements of the cast gold crown prior to cementation. The findings through this study could be summarized as follows; 1. The accuracy of combined impression was superior to that of alginate impression, but it was inferior to that of rubber base impressions. 2. Combined impressions produced a little distortion of the mesio-distal length, alginate impressions produced the largest distortion, ut rubber base impressions produced the least distortion.