CONFINED DENTIN CRACK OBSERVATION BY OPTICAL COHERENCE TOMOGRAPHY & DIGITAL RADIOGRAPHY METHODS

Abstract

Tooth fractures are common clinical findings. An observational study conducted by Journal of the American Dental Association (JADA) indicated that almost 70% of patients in general dental practices had at least one cracked posterior tooth. The key factor to save cracked teeth is by early detection and precise information about cracks' depth. Several diagnostic aids have been used to detect and visualize cracks clinically. Some studies have pointed out the potential of optical coherence tomography (OCT) to detect and quantitatively evaluate cracks in teeth whereas the use of digital radiography is controversial. This in vitro study was performed to determine the ability of OCT and digital radiography in conjunction with Methylene Iodide (MI) as a contrast medium to detect cracks in dentin and determine their depth. Six de-identified human molar cracked teeth with 18 dentinal cracks observed on their occlusal surfaces were used in this study. Several scans were taken at different depths from the surface using a spectral domain OCT system with a wavelength of 840 nm to investigate to which depth the crack remained visible to the system. Digital Radiographs were obtained at 0 degree (buccolingual direction of tooth) before and after MI application and were obtained at angles of 10, 20, 30, 40, -10, -20, -30, -40 degrees. The crack depth was measured at the angulation which showed the crack most clearly in digital images. Accuracy was evaluated using micro computed tomography (Micro CT) scans. This work supported the use of digital radiography combined with Methylene Iodide (MI) as contrast material in crack detection even if not along the x-ray beam. On the other hand, neither digital radiography nor OCT was capable to measure the entire depths of dentinal cracks. Methylene Iodide was found to evaporate spontaneously. Clinical trials will be required for routine clinical use.