LASER EFFECTS ON DENTAL HARD TISSUES

激光对牙齿硬组织的影响

• 批准号: 2443676
• 负责人: JOHN D FEATHERSTONE
• 金额: $ 26.6万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-07-01 至 1998-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2443676
• 关键词: X ray crystallography; apatites; cementum; computer simulation; crystallization; dental caries; dental pulp; dentin; heat; infrared spectrometry; laser therapy; lasers; phase change; preventive dentistry; radiation therapy dosage; radiochemistry; scanning electron microscopy; solubility; tooth enamel; tooth root

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.

正在验证的基本假设是“有一个特定的 最有效的激光光的辐照条件集 有效与牙科硬组织相互作用”。 通过二氧化碳（CO2）激光灯光已明显显示出搪瓷（CO2） 抑制随后的酸诱导的脱源性。 有效的转换 当激光束与牙齿硬性相互作用时，轻能量会加热 组织取决于几个激光参数，包括波长， 脉冲宽度和通量。 潜力非常适合临床使用 特定波长激光器，以防止随后的龋齿 攻击和治疗早期病变。 在临床之前 可以实现应用的科学基础 必须建立特定条件，安全问题必须是 解决。 这里提出的研究的目的是确定 基础。 这些目标将通过以下特定目标来实现； （1）确定牙齿硬组织的吸收系数 二氧化碳激光辐射的选定波长（9.3.9.6。10.3和10.6 MUM）。 这将通过使用详细测量的组合来实现 表面温度和热电导的广泛热模拟 和相变。 （2）研究搪瓷的热行为， 使用二氧化碳激光的选定条件的牙本质和合成磷灰石 辐照。 这个目标有几个组成部分。 （a）对心脏的研究 波传播和与数值模拟的比较。 （b）研究 单一和多脉冲辐照效应（i）以了解 过去的多个脉冲实验，（ii）评估其有效性 在扩展时导致重结晶和/或反应性修改 深度和（iii）评估内部内部的热攻击 牙齿，特别是果肉区域。 这个细分市场将导致未来 更广泛的安全研究。 （30进行体外实验 确定二氧化碳激光波长和辐照条件（a）降低 牙齿矿物质的溶解度，（b）抑制 搪瓷和牙根中的龋齿状病变。 表面变化导致 通过扫描电子显微镜评估二氧化碳的治疗， X射线衍射，红外光谱，化学分析以及通过 使用双重恒定组成方法的详细溶解研究。 一系列CO2激光照射对治疗的抑制作用 （a）声音中人造龋齿病变进展的条件 牙釉质，（b）声根，A（c）初始龋齿状病变 （i）光滑的表面搪瓷； （ii）牙釉质的咬合坑和裂缝； （iii） 牙根表面将通过体外pH循环评估 去矿化/回忆模型。 （40确定激光器 波长和条件将构成未来临床的基础 研究。 预计目前的研究将提供范围 特定的激光条件，随后可以对此进行检查 安全和临床功效。 如果成功，这将提供 改进的治疗坑和裂缝龋齿的方法，早期龋齿ND 光滑的表面搪瓷龋。