Construction of in vitro caries progressing system and effect of cavity size in dentin lesion on caries progression

2003 Fiscal Year Final Research Report Summary

• Project/Area Number: 13671992
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Conservative dentistry
• Research Institution: HOKKAIDO UNIVERSITY
• Principal Investigator: KOMATSU Hisanori Hokkaido Univ., Grad.School of Dent., Asso Prof., 歯学研究科, 助教授 (30002182)
• Co-Investigator(Kenkyū-buntansha): NODA Mamoru Hokkaido Univ., Grad.School of Dent., Inst., 大学院・歯学研究科, 助手 (10301889) ; KOBAYASHI Youichi Hokkaido Univ., Med., Dent., Hospital, Inst., 医学部・歯学部附属病院, 助手 (80231322)
• Project Period (FY): 2001 – 2003
• Keywords: Caries / pH cycling system / Demineralization / Remineralization

Research Abstract

Assessment of caries risk and enhancement of remineralization are important subjects in treatment of caries. Caries risk could be predicted by frequency of carbohydrate consumption. We manipulated the in vitro caries progressing system in order to evaluate the effect of carbohydrate consumption on caries progression. As a result, automatic pH-cycling system consisted of two solutions of different pH, two peristaltic pump, and a time controller was generated. By replicating the pH-cycle with carbohydrate consumption, one pH-cycle that was set in which the time took for retention under pH 5.5 was 37 mins and the time took for recovery to pH 7.0 was 60 mins. Comparing the caries progression of human enamel between 3 pH-cycle/day and 9 pH-cycle/day, the difference became significant after 4 weeks of the experiment. This system automatically provides successive de-and re-mineralization and sets up an environment with high caries risk, and also enables periodical observation of thin section of tooth for microradiography. In attempt to the effect of caries progression of cavity size in dentin lesion, caries progression in fissure of teeth after pH-cycling was observed. The possible explanation for not finding a significant difference could be due to the variety of the depth and width of fissure. Therefore, artificial tooth fissure in different width were prepared and applied pH-cycling. In caries progression in dentin surrounding the bottom of fissure, rapid progression of wider fissure was found relative to that of narrower fissure when comparing the fissure width.