Loganathan Sarathkumar, Santhanakrishnan Soundarapandian, Bathe Ravi, Arunachalam Muthukumaraswamy
Indian Institute of Technology Madras, Manufacturing Engineering Section, Department of Mechanical Engineering, Adyar, Chennai, 600036, India.
Indian Institute of Technology Madras, Manufacturing Engineering Section, Department of Mechanical Engineering, Adyar, Chennai, 600036, India.
J Mech Behav Biomed Mater. 2021 Mar;115:104256. doi: 10.1016/j.jmbbm.2020.104256. Epub 2020 Dec 11.
For high precision laser surgery, noninvasive tool for prediction of laser ablation profile beforehand is imperative. The present study proposed a method to utilize nondestructive FTIR and Raman probes for predicting laser ablation profile overcoming the challenge of heterogeneity on individual target tissue. By ascribing the chemical heterogeneity of teeth drive their differential machining capability, the study establishes a correlation between the chemical composition and their ablation parameters (ω,D and F). The chemical composition of teeth was obtained by noninvasive tools (FTIR and Raman) in terms of absorption peak intensity. To further correlate with key laser ablation parameters, the laser irradiation study was carried out using 800 nm, 100 fs, Ti:Sapphire laser. The surface morphology of irradiated sample was measured by optical profiler. A strong correlation was observed between laser ablation parameters and peak intensity of phosphate group for both FTIR and Raman spectroscopy. The concentration of phosphate group shows a positive relationship to ablation threshold fluence, while the effective Gaussian beam radius and effective energy penetration depth show negative correlation. Both nondestructive probes show good linearity which enable us to extrapolate the key laser ablation parameters for predicting laser ablation profile on random dentin and enamel samples. The ablation profiles predicted based on both FTIR and Raman are well-matched in dentin, whereas it shows a slight deviation in enamel. The predicted profiles are consistent with experimental results at lower power whereas it shows a slight deviation at higher power due to screening effect. Thus, FTIR and Raman probes can be used to predict laser ablation profile nondestructively in real-time and obviate the need for trial runs. Furthermore, the present study has predicted the laser ablation rate and ablation efficiency for performing laser surgery in optimum laser processing conditions irrespective of teeth heterogeneity.
对于高精度激光手术而言，事先预测激光消融轮廓的非侵入性工具至关重要。本研究提出了一种利用无损傅里叶变换红外光谱（FTIR）和拉曼探针来预测激光消融轮廓的方法，克服了个体目标组织异质性的挑战。通过归因牙齿的化学异质性来驱动其不同的加工能力，该研究建立了化学成分与其消融参数（ω、D和F）之间的相关性。牙齿的化学成分通过无损工具（FTIR和拉曼）以吸收峰强度的形式获得。为了进一步与关键激光消融参数相关联，使用800纳米、100飞秒的钛宝石激光进行了激光辐照研究。用光学轮廓仪测量辐照样品的表面形貌。FTIR和拉曼光谱的激光消融参数与磷酸基团的峰强度之间均观察到强相关性。磷酸基团的浓度与消融阈值通量呈正相关，而有效高斯光束半径和有效能量穿透深度呈负相关。两种无损探针均显示出良好的线性，这使我们能够外推关键激光消融参数，以预测随机牙本质和牙釉质样品上的激光消融轮廓。基于FTIR和拉曼预测的消融轮廓在牙本质中匹配良好，而在牙釉质中则略有偏差。在较低功率下，预测轮廓与实验结果一致，而在较高功率下，由于屏蔽效应则略有偏差。因此，FTIR和拉曼探针可用于实时无损预测激光消融轮廓，无需进行试运行。此外，本研究预测了在最佳激光加工条件下进行激光手术的激光消融速率和消融效率，而不考虑牙齿的异质性。
