LASER EFFECTS ON DENTAL HARD TISSUES

本提案中有待检验的基本假设是， 存在一组特定的激光照射条件， 最有效地与牙齿硬组织相互作用。的 当激光束相互作用时，光能有效地转化为热 与牙齿硬组织的接触具有强烈的波长依赖性。的潜在 对于特定激光器的临床使用是极好的， 预防龋齿和治疗早期病变。之前 为临床应用提供了科学依据， 选择的具体条件必须建立和安全问题 必须加以解决。本研究建议的目的是 建立这个基础。研究中使用的激光器被选择用于 从IR到UV检查最可能有用的波长，即 CO2（9.3-11.0 μ m），Nd：YLF（1.o5 μ m，与Nd：YAG相当），以及 其谐波为0.53和0.35微米。漫透射广告 将使用牙釉质、牙本质 和合成碳酸磷灰石（CAP）。散射和吸收 将确定系数。我们将定量地确定 热传播到不同厚度的牙釉质和牙本质中， 选择的激光照射条件（脉冲长度，能量，重复频率， 脉冲数）。将检查激光相互作用（使用条件 由光学和热研究确定），其中（1） 牙釉质、牙根和合成碳酸磷灰石，和（2） 在（a）牙釉质光滑和咬合面中的龋样损伤， (b)根面有或无牙骨质，全部有或无 氟化物处理在所有情况下， 病变后将进行研究，以测量病变的抑制作用 使用Ph周期模型进行进展。结果将使用 偏振光显微镜定量组合 显微射线照相，x射线衍射，红外光谱，扫描 电子显微镜和化学分析。安全性指标 将通过热研究和以下方法评估治疗 牙髓腔和外表面的温度测量。 所有数据将进行统计分析并解释以表明 特定的辐照条件是否与特定的 牙科硬组织和矿物质的结果。预计， 本研究将提供一系列激光照射条件， 将优化增加抗龋性的有益效果 最终目的是开发一种激光系统， 一种改进的窝沟病防治方法 龋、早期釉质龋和根龋。

The underlying hypothesis to be tested in the present proposal is that there is a specific set of irradiation conditions for laser light that most efficiently and effectively interacts with dental hard tissues. The efficient conversion of light energy to heat when a laser beam interacts with dental hard tissues is strongly wavelength dependent. The potential is excellent for the clinical use of specific lasers to provide protection against caries and for the treatment of early lesions. Before the clinical application can be realized the scientific basis for the choice for the specific conditions must be established and safety issues must be addressed. The purpose of the studies proposed here is to establish that basis. Lasers used in the studies have been selected to examine the most likely useful wavelength from IR though UV, namely CO2(9.3-11.0 micro m), Nd:YLF (1.o5 micro m, comparable to Nd:YAG), and its harmonics at 0.53 and 0.35 micro m. Diffuse transmission ad backscattering will be examined at all wavelengths using enamel, dentin and synthetic carbonated apatite (CAP). Scattering and absorption coefficients will be determined. We will determine quantitatively the heat propagation into enamel and dentin of various thicknesses using selected laser irradiation conditions (pulse length, energy, rep-rate, number of pulses). Laser interactions will be examined (using conditions determined from the optical and thermal studies) with (1) surfaces of tooth enamel, tooth roots and synthetic carbonated apatite, and (2) caries-like lesions in (a) dental enamel smooth and occlusal surfaces, (b) root surfaces with and without cementum, all with or without fluoride treatment. In all cases the experiments with caries-like lesions will be followed by studies to measure the inhibition of lesion progression using a Ph cycle model. Results will be assessed using a combination of polarized light microscopy, quantitative microradiography, x-ray diffraction, infrared spectroscopy, scanning electron microscopy, and chemical analysis. An indication of safety of the treatments will be assessed from the thermal studies and by temperature measurements in the pulp chamber and at the outer surfaces. All data will be analyzed statistically and interpreted to indicate whether specific irradiation conditions are associated with specific outcomes in dental hard tissues and mineral. It is anticipated that the present study will provide a range of laser irradiation conditions that will optimize the beneficial effects of increasing caries resistance with the ultimate aim of developing a laser system(s) for use as an improved method for the prevention and treatment of pit and fissure caries, early enamel caries, and root caries.