LASER EFFECTS ON DENTAL HARD TISSUES

本提案中要检验的基本假设是 对于激光，有一组特定的照射条件 最高效、最有效地与牙齿硬组织相互作用。这个 激光相互作用时光能到热能的有效转换 与牙齿硬组织有强烈的波长依赖性。潜力 是为临床使用特定激光提供极佳的 预防龋齿和治疗早期皮损。在此之前 为临床应用提供了科学依据。 对于具体条件的选择必须确定和安全问题 必须解决的问题。这里提出的研究的目的是 奠定这一基础。研究中使用的激光已被选为 检查从IR到UV的最有可能有用的波长，即 CO2(9.3-11.0微米)，NdYLf(1.05微米，与NdYAs相当)，以及 其在0.53微米和0.35微米处的谐波扩散传输 将使用牙釉质、牙本质在所有波长检查后向散射 和合成碳化磷灰石(CAP)。散射和吸收 系数将被确定。我们将定量地确定 热在不同厚度的牙釉质和牙本质中的传播 选定的激光照射条件(脉冲长度、能量、折射率、 脉冲数)。将检查激光相互作用(使用条件 由光学和热学研究确定)具有(1)表面 牙釉质、牙根和合成碳化磷灰石，以及(2) (A)牙釉质光滑和咬合面的龋样病变， (B)有或没有牙骨质的牙根表面，不论是否有牙骨质 氟化物治疗。在所有情况下，对类龋齿的实验 损伤之后将进行研究，以测量损伤的抑制程度 使用Ph循环模型的进展。结果将使用 偏振光显微镜的组合，定量 显微放射照相、x射线衍射、红外光谱、扫描 电子显微镜和化学分析。表明……的安全性 这些治疗方法将通过热研究和 测量牙髓腔内和外表面的温度。 所有数据都将进行统计分析和解释，以表明 特定的照射条件是否与特定的 牙科硬组织和矿物质的结果。据预计， 本研究将提供一系列激光照射条件， 将优化提高防龋性的有益效果 最终目标是开发一种激光系统(S)，用作 坑洞裂缝防治的改进方法 龋病、早期釉质龋病和根面龋病。

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.