LASER EFFECTS ON DENTAL HARD TISSUES

目前正在测试的基本假设是“有一种特定的 一组激光的照射条件，最有效和 有效地与牙齿硬组织相互作用。牙科治疗 二氧化碳(CO2)激光对牙釉质的影响明显 抑制后续酸诱导的脱矿。高效的转换 激光与牙齿硬质相互作用时产生的光能 组织取决于几个激光参数，包括波长， 脉冲宽度和通量。具有良好的临床应用潜力。 用于预防后续龋齿的特定波长激光 治疗早期皮损。在临床之前 可实现应用的科学依据，为选择 必须建立特定的条件，并必须解决安全问题 地址。这里提出的研究的目的是要确定 基础。这些目标将通过以下具体目标实现； (1)测定牙齿硬组织的吸收系数 选定波长(9.3.9.6.10.3微米和10.6微米)二氧化碳激光辐射。 这将通过使用以下详细测量的组合来实现 表面温度和广泛的导热系数热模拟 和相变。(2)研究牙釉质的热行为， 牙本质和合成磷灰石使用选定条件的二氧化碳激光 辐射。这一目标有几个组成部分。(A)心脏研究 波的传播及其与数值模拟的比较。(B)研究 单脉冲和多脉冲辐照效应(一)理解 过去的多脉冲实验，(Ii)评估它们对 导致再结晶和/或反应性修改 深度，和(Iii)评估内部的热攻击 牙齿，尤其是牙髓区域.这一细分市场将通向未来 更广泛的安全研究。(30)进行体外实验，以 确定二氧化碳激光波长和照射条件，以(A)减少 牙齿矿物质的溶解性，以及(B)抑制牙周炎的进展 牙釉质和牙根中的龋样病变。由此产生的曲面更改 将通过扫描电子显微镜对二氧化碳激光治疗进行评估， X射线衍射、红外光谱、化学分析和 使用双恒定组成方法学进行详细的溶出度研究。 一定范围的CO2激光照射对治疗的抑制作用 (A)声音中人工龋样病变进展的条件 牙釉质，(B)健全的牙根，(C)最初的龋样病变 (I)表面光滑的釉质；。(Ii)牙釉质的咬合窝和裂隙；。(Iii) 牙根表面将通过体外pH循环进行评估 脱矿/再矿化模型。(40)以确定激光 将构成未来临床基础的波长和条件 学习。预计目前的研究将提供一个范围 特定激光条件，随后可根据以下内容进行检查 安全性和临床疗效。如果成功，这将提供 窝沟龋病、根面龋病和早期龋病治疗方法的改进 表面光滑的釉质龋齿。

The underlying hypothesis that is being testes is "that there is a specific set of irradiation conditions for laser light that most efficiently and effectively interacts with dental hard tissues". Treatment of dental enamel by carbon dioxide (CO2) laser light has been shown to markedly inhibit subsequent acid-induced demineralization. The efficient conversion of light energy to heat when a laser beam interacts with dental hard tissues is dependent on several laser parameters, including wavelength, pulse width and fluence. The potential is excellent for the clinical use of specific wavelength lasers for protection against subsequent caries attack and for the treatment of early lesions. Before the clinical application can be realized the scientific basis for the choice of the specific conditions must be established and safety issues must be addressed. The purpose of the studies proposed here is to establish that basis. The objectives will be achieved by the following specific aims; (1) To determine the absorption coefficients for dental hard tissues at selected wavelengths (9.3.9.6. 10.3 and 10.6 mum) of CO2 laser radiation. This will be achieved by using a combination of detailed measurements of surface temperatures and extensive thermal simulations of heat conductance and phase transformations. (2) To study the thermal behavior of enamel, dentin, and synthetic apatite using selected conditions of CO2 laser irradiation. This aim has several components. (a) Study of the heart wave propagation and comparison with numerical simulations. (b) Study of single and multiple-pulse irradiation effects in order (i) to understand past multiple-pulse experiments, (ii) to evaluate their effectiveness to cause recrystallization and/or reactivity modification over an extended depth, and (iii) to evaluate the thermal assault of the interior of the tooth, particularly athe pulp region. This segment will lead to future more extensive safety studies. (30 To carry out in vitro experiments to determine CO2 laser wavelength and irradiation conditions that (a) reduce the solubility of dental mineral, and (b) inhibit the progression of caries-like lesions in enamel and tooth roots. Surface changes resulting from CO2 laser treatment will be assessed by scanning electron microscopy, x-ray diffraction, infrared spectroscopy, chemical analysis, and by detailed dissolution studies using dual constant composition methodology. The inhibitory effect of treatment by a range of CO2 laser irradiation conditions on progression of artificial caries-like lesions in (a) sound dental enamel, (b) sound tooth roots, an (c) initial caries-like lesions in (i) smooth surface enamel; (ii) occlusal pits and fissures of enamel; (iii) tooth root surfaces will be assessed by an in vitro pH cycling demineralization/remineralization model. (40 To determine laser wavelengths and conditions that will form the basis of future clinical studies. It is anticipated that the present studies will provide a range of specific laser conditions that can subsequently be examined with regard to safety and clinical efficacy. If successful, this would provide improved methods for treating pit and fissure caries, root caries nd early smooth surface enamel caries.