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.

正在验证的潜在假设是“存在一种特定的 一组激光的照射条件， 有效地与牙齿硬组织相互作用”。 治疗牙 用二氧化碳（CO2）激光照射牙釉质， 抑制随后酸诱导的脱矿作用。 有效地转化 当激光束与牙齿硬物相互作用时， 组织依赖于几个激光参数，包括波长， 脉冲宽度和能量密度。 具有良好的临床应用前景 特定波长的激光，用于防止随后的龋齿 用于治疗早期病变。 临床前 应用可以实现的科学依据的选择， 必须建立具体的条件，安全问题必须 处理。 这里提出的研究的目的是确定， 基础 这些目标将通过以下具体目标实现： (1)测定牙体硬组织的吸收系数， 选定波长（9.3.9.6. 10.3和10.6 μ m）的CO2激光辐射。 这将通过使用以下详细测量的组合来实现： 表面温度和广泛的热传导热模拟 和相变。 (2)为了研究搪瓷的热行为， 牙本质和合成磷灰石，使用选定的CO2激光条件 辐照 这一目标有几个组成部分。 (a)心脏研究 波的传播和数值模拟的比较。 (b)研究 单脉冲和多脉冲辐照效应，以便（i）了解 过去的多脉冲实验，（ii）评估其有效性， 引起在延长的反应时间内的重结晶和/或反应性改变。 深度，以及（iii）评估内部的热攻击 牙齿，特别是牙髓区域。 这一部分将导致未来 更广泛的安全性研究。 (30进行体外实验， 确定CO2激光波长和照射条件， 牙矿物质的溶解度，和（B）抑制牙矿物质的进展， 牙釉质和牙根中的龋齿样病变。 表面变化导致 将通过扫描电子显微镜评估CO2激光治疗的效果， X射线衍射，红外光谱，化学分析，并通过 使用双恒定组成方法的详细溶出研究。 一系列CO2激光照射治疗的抑制作用 人工龋样病变进展的条件（a）声音 牙釉质，（B）健全的牙根，和（c）初始龋样病变， (i)光滑表面釉质;（ii）釉质的咬合凹陷和裂缝;（iii） 牙根表面将通过体外pH循环进行评估 脱矿/矿化模型 (40确定激光 波长和条件，将形成未来临床的基础， 问题研究 预计目前的研究将提供一系列 随后可以检查特定的激光条件， 安全性和临床疗效。 如果成功，这将为 治疗窝沟龋、根龋和早期龋的改进方法 光滑面釉质龋。