Feasibility study on microcrack detection using laser lock-in thermography using visible laser on tooth

• Main Author: Low, Kenneth Yan Wei
• Other Authors: Wong, Brian Stephen
• Format: Final Year Project
• Language: English
• Published: 2019
• Subjects: DRNTU::Engineering::Materials::Biomaterials
• Online Access: http://hdl.handle.net/10356/78716
• Institution: Nanyang Technological University

The timely and proper diagnosis and treatment of microcracks in teeth is of paramount importance to improve the tooth prognosis. Early diagnosis of a crack in a tooth and its early treatment is vital to prevent further splitting. For instance, Bicuspids and molars frequently develop microcracks. When left untreated, they fracture and split mesiodistally into buccal and lingual fragments. Treatment is only by extraction [1]. The pain and oral disfunction caused by cracks on the tooth burdens patients economically, physically and mentally. Even though various treatment options for tooth fracture had been developed over the past decade [2-4], dental practitioners still experience difficulty in performing a diagnostic evaluation of microcracks. This is mainly due to limitations in the available and commonly used examination methods. Needle inspection, fracture staining, dental light microscopy and radiography are the most commonly used diagnostic techniques. These techniques possess inherent limitations such as exposure to radiation, resolution limits and visual limits – these limitations will be discussed in further detail later in this report. Therefore, an alternative method for dental inspection that can overcome these limitation for clinical application is sought. The prevalence of NDT has taken centre stage in industry and research institutions as an effective tool for quality control of materials and as an evaluation technique. Its main advantage as an evaluation technique is that it allows analysis to take place without altering or destroying the sample material [5]. It is for this very reason that it has high potential for usage in medical viii diagnosis, and dentistry in particular. Common modern NDT method includes ultrasound, X- ray imaging, echography, nuclear magnetic resonance and eddy currents. There is a plethora of NDT techniques such as Infrared Thermography, Speckle Shear Interferometry, and Electronic Speckle Pattern Interferometry (ESPI) that are commonly used to inspect new materials with variable success. This is especially so in the aerospace industry where inspection must be done with high precision and accuracy – without altering the physical property of the sample material. These non-contact techniques are able to obtain images in relatively short periods of time and they examine over a large surface area. However, exploration of NDT usage for dental application is lacking. The aim of this project is to explore the feasibility of using laser lock-in thermography technique to detect microcracks on teeth. Lock-in thermography has shown the most potential as an dental inspection method due to its proven ability to provide higher resolution phase images for microcrack detection in aerospace materials and structures. It also eliminates the inherent risk of exposure to radiation from radiography which will benefit at risk individuals seeking dental care such as pregnant women or children.This report comprises of review of research studies on laser lock-in thermography for dental application, its viability, safety and accuracy for microcrack detection on tooth