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Title: 0961 - Precise Control of Cortical-Bone Ablation Depth Using Picosecond Laser

Authors:

Fusong Yuan (Presenter)
Peking University School and Hospital of Stomatology

Peijun Lyu, Peking University School and Hospital of Stomatology
Jianjiang Zhao, Peking University School and Hospital of Stomatology

Abstract:

Objectives: To study the quantitative relationships among the number of focal plane additive pulse layers in two-dimensional ablations, Z-axis feed rate and ablation depth during the ablation of cortical bone by a numerically controlled 3-axis picosecond laser, and to establish appropriate methods for precise control of ablation depth.

Methods: Two-dimensional ablation was carried out on the rib blocks repeatedly in the focal plane according to a preset circular path using a picosecond laser device and an 3-axis numerically controlled micro laser galvanometer scanner, with the respective number of additive pulse layers (n)=5, 10…65 and 80, to obtain the maximum depth of two-dimensional ablation and the quantitative relationship between the number of pulse layers and ablation depth within the maximum ablation depth (n/d). Control software developed in-house was used to set the ablation size and shape as a circular cavity with a diameter of 3 mm, and the Z-axis feed rate was set at a single-step size of d µm after ablation of n layers according to the quantitative relationship between the number of pulse layers and ablation depth within the maximum ablation depth. The measured and theoretical values of the ablated cavities were compared to obtain n and d values corresponding to the minimum difference and to evaluate the ablation depth error; based on the n value corresponding to the minimum ablation depth error, a more accurate d value was obtained, so as to set the Z-axis feed rate for ablation to produce cylindrical cavities with diameter and depth of 3 mm each, and to evaluate the precision of ablation.

Results: The functional expression of the n/d quantitative relationship derived through linear fitting is d=9.2784n + 26.763, R2 = 0.9889, and d can be controlled with 15.42 ± 5.44 µm precision. Thus, high-quality cortical-bone ablation can be achieved using a picosecond laser with the parameters employed in this study.

Conclusions: Experimental results showed that high-quality cortical bone ablation can be achieved by picosecond laser with the parameters used in this study. Precise control of the depth of cortical bone laser ablation can be attained by optimising the parameters of single-step ablation during the use of a numerically controlled picosecond laser.

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Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE

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