Medical Lasers; Engineering, Basic Research, and Clinical Application  
Near-infrared Laser Energy Transmission through Teeth with Crack Lines: An In-vitro Study
Ashita Sapra, Arun Darbar, Roy George
School of Medicine and Dentistry, Griffith University, Gold Coast, Australia
Correspondence to: Roy George
School of Medicine and Dentistry, Griffith University, Gold Coast, QLD 4215, Australia
Tel.: +61-7-5678-0751
Received: August 30, 2021; Accepted: October 27, 2021; Published online: November 25, 2021.
© Korean Society for Laser Medicine and Surgery. All rights reserved.

This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Background and Objectives
To evaluate the difference in near-infrared (810 nm) laser energy transmission through teeth with and without cracks.
Materials and Methods
Extracted teeth were sectioned and examined visually for the presence of cracks with the aid of photographs and a trans-illuminator. Fourteen sections, each with cracks (Group A) and no cracks (Group B) were identified and placed 15 mm from the tip of a 300 micron fiber, prior to activation with an 810 nm diode laser (0.1W, 50 ms interval,100 ms duration). A power meter positioned behind the tooth recorded the average energy that was transmitted through the samples. Unpaired t-test analysis was used to determine if the tooth sections with cracks allowed higher power passage compared to sound teeth.
The mean power recording for the cracked teeth (Group A) was significantly greater (p = 0.0005) than that for the non-cracked teeth (Group B).
Within the limitations of this study, it is evident that significantly higher laser energy passes through teeth with cracks in comparison to teeth without cracks. A recent clinical study has also shown that lasers could be used to assess symptomatic cracked teeth. Hence, further research is required to determine the relative increase in energy required to identify symptomatic cracked teeth.
Keywords: Cracked teeth; Near-infrared lasers; Endodontics; Diagnosis; Laser transmission

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