레이저 조사의 치아우식 억제효과에 관한 실험적 연구

Abstract

[한글]

초기 우식 병소에서 레이저 조사에 의한 우식진행 억제효과를 규명하기 위해 자연치를 대상으로 STPP 인공우식 용액 (0.1M 젖산에 0.24mM Sodiumtripolyphosphate를 첨가하고 sodium hydroxide로 pH 4.2가 되도록 조정)을 사용하여 우식병소를 형성하고 탄산가스 레

이저를 10J/㎠, 20J/㎠, 30J/㎠, 40J/㎠, 5J/㎠의 세기로 조사한 후 원자흡수 및 자외선 분광측광계로 칼슘과 인의 용출량을 측정하여 내산성 증가에 가장 효과적인 조사세기를 결정한 다음, 표본을 다시 대조군(비처리군), Ⅰ군(레이저 조사군, 40J/㎠), Ⅱ군(불소 도포군, 1.23% APF) 그리고 피군(불소 도포와 레이저 조사 병용군)으로 나누어 각각 처리하고 계속적으로 인공우식을 야기시킨 후 우식법랑질 표면의 미세경도를 측정하고 표면변화를 주사전자현미경으로 관찰하여 초기 우식병소의 진행억제 효과를 평가한 바 다음과 같은 결론을 얻었다.

1. 초기 인공우식법랑질의 레이저 조사에 의한 내산성 증가는 30J/㎠ 이상에서 유의성 있게 증가하였으며 효과적인 조사 세기는 40J/㎠와 50J/㎠ 였다.

2. 레이저 조사에 의해 초기 인공우식법랑질 표층부 (20μm, 50μm)에서의 우식진행이 억제되었다.

3. 레이저 조사군(40J/㎠)의 우식진행 억제 효과는 표층(20μm)에서 불소(1.23% APF) 도포군 및 레이저 조사와 불소도포 병용군에 비해 떨어졌으나, 50μm 깊이에서는 3개군 모두 같았다.

4. 레이저 조사군(40J/㎠), 불소(1.23% APF)도포군 그리고 레이저 조사와 불소 도포 병용군 모두 100μm 깊이 이상에서는 우식진행 억제 효과를 관찰할 수 없었다.

[영문]

The purpose of this study was to evaluate the inhibitory effect on demineralization of enamel of initial carious lesion by irradiation of laser.

For this study, crowns of extracted human premolar teeth were sectioned sagitally (Mesio-distal and bunco-lingual) and sound buccal or lingual enamel 2 surfaces were selected for experimental specimens, and initial carious lesions were produced

artificially using demineralizing solution (STPP, 0.1M Latic acid containing 0.2mM Sodium tripolyphosphate, brought pH to 4.2 with adding sodium hydroxide).

For determining the most effective irradiation energy of laser to increase acid-resistance of enamel,120 specimens were irradiated with CO^^2 laser under condition of energy density with 10J/㎠, 20J/㎠, 30J/㎠, 40J/㎠ and 50J/㎠. All of those specimens were exposed to 0.5N HCIO^^4 solution containing 0.5% LaCI^^3 for 60 seconds for demineralization. Dissolved calcium and phosphate concentration in this solution were determined by the atomic absorption and the U-V spectrophotometer.

For evaluation of the inhibitory effect of laser irradiation on enamel demineralization, 150 specimens were divided into 2 groups to test microhardness (100 specimens) and observe ultra-structural surface changes (50 specimens) of enamels. It each group, they were divided again into 5 sub-groups as ACL (Artificial carious lesion), Control (No treatment), Group Ⅰ (Laser irradiation only, 40J/㎠), Group Ⅱ (Fluo-ride application only, 1.23% APF) and Group Ⅲ (Fluoride appliaction+Laser irradiation). ALL treated specimens were exposed to STPP solution again for 5 days to produce carious lesion progressively, and then tested microhardness of exposed surface of enamels with microhardness tester and observed ultra-structural surface changes with SEM.

The results were as follows.

1. The acid-resistance of initial carious lesions increased significantly when irradiated 30J/㎠ energy and tint effective energy of irradiation for increasing acid-resistance were 40J/㎠ and 50J/㎠.

2. Laser irradiation on initial carious lesion was effective for inhibiting caries profession at 20μm and 50μm in depth.

3. Group Ⅰ (Laser irradiation only, 40J/㎠) showed inhibition of caries progression less effective than that of group Ⅱ (Fluoride application only, 1.23% APF) and group Ⅲ (Fluoride application+Laser irradiation) in 20μm depth but 50μm in depth all three groups showed same effect.

4. All groups did not show any inhibitory effect on caries progression under 100μm in depth.