ORIGINAL RESEARCH Laser-assisted diagnosis of symptomatic cracks in teeth with cracked tooth: A 4-year in-vivo follow-up study Ashita Sapra, BOH DS, GradDip 1 ; Arun Darbar, BDS 2 ; and Roy George, BDS, MDS, PhD, MRACDS, GCHE, FRCS(Edin) 1 1 School of Dentistry and Oral Health, Griffith University, Gold Coast, Queensland, Australia 2 Private Practice, Smile Creations Dental Innovations, Leighton Buzzard, UK Keywords cracked tooth, diode laser, endodontics, laser diagnosis, vitality test. Correspondence Associate Professor Roy George, Discipline Lead Endodontics, Griffith University, Gold Coast, QLD 4215, Australia. Email: drroygeorge@gmail.com doi: 10.1111/aej.12391 (Accepted for publication 6 November 2019.) Abstract The purpose of this study was to determine whether a near-infrared diode laser could be used as an adjunct to help identify and localise symptomatic cracks in patients with cracked tooth. An 810-nm diode laser at 1 W continuous wave energy with a 200 micro-fibre tip was used to scan the offending tooth. Crack identified during the laser scan was removed, restored and reviewed after four weeks and after 4 years. The laser was able to significantly (P = 0.0001) iden- tify suspected cracked teeth from non-cracked control teeth. Of the twelve patients examined, ten participants experienced discomfort as the laser passed over a crack line. At 4-week and 4-year recall, a majority of the ten treated patients responded positively to the management of crack. This study showed that diode laser could be an adjunctive tool for early detection and manage- ment of symptomatic cracks with the possibility of improving long-term survival. Introduction Cracked tooth can be a difficult disorder to diagnose and manage (1,2). In an ageing population where people are retaining teeth for many decades, the prevalence of cracked tooth is likely to increase (3). Failure to diagnose the condition early could result in eventual crack progression, pulpal necrosis and potential tooth loss (4). Tooth splits or fractures are the third most common reason for tooth loss in developed countries (5). With time, the prognosis of the tooth worsens and the cost of treatment increases (6). Early diagnosis may result in treatment with a simple restoration. However, if it pro- gresses to communicate with the pulp, root canal treat- ment and cuspal coverage restoration are often necessary (7,8). Currently, diagnosis of cracked tooth is largely depen- dent on the patients’ signs and symptoms (e.g. thermal sensitivity and pain on bite and release) (7,9). However, these symptoms can mimic an array of other pathologies. The ‘bite test’, an important diagnostic tool for assess- ment of teeth with cracked tooth, can potentially propa- gate the crack further (10,11). Trans-illumination, an adjunct diagnostic technique used in diagnosis of cracked tooth, is reliant on the correct interpretation of visible crack lines (1). Fracture lines diffract the light in such a way that the fractured segments are illuminated differen- tially; however, subtle changes in contrast of the trans-il- luminated crack line can make interpretation difficult; craze lines can be incorrectly visualised as structural cracks (1). Furthermore, it may be very difficult to deter- mine the location and direction of the crack/s responsible for patient symptoms (1,9). The purpose of this study was to determine whether a near-infrared 810-nm diode laser could be used as novel and adjunct method to help identify and localise symp- tomatic cracks in patients with cracked tooth. Materials and method The Griffith University Expedited Ethical Review com- mittee approved this study (Protocol Number DOH/03/ 13/HREC). Patients who attended Griffith University Undergraduate Dental Clinic, identified with symptoms of cracked tooth, were invited to participate in the study. All patient referrals had to meet the inclusion and exclu- sion criteria. As the risk of laser is uncertain in pregnant and breastfeeding patients, this group of patients was excluded. Also, patients with dental caries, defective restorations, endodontic treatment on tooth in question, © 2019 Australian Society of Endodontology Inc 1 Aust Endod J 2019