_Applied_  
_sciences_  
_Article_  
**Utilization of Er:YAG Laser in Retrieving and Reusing of Lithium Disilicate and Zirconia Monolithic Crowns in Natural Teeth: An In Vitro Study**  
**[PERSON] 1,2\({}^{\text{\textregistered}}\),** **[PERSON] 3,4,5,*\({}^{\text{\textregistered}}\),** **[PERSON] 6, [PERSON] 7,**  
**[PERSON] 2\({}^{\text{\textregistered}}\) and [PERSON] 1**  
1 Department of Periodontology, School of Dentistry, Virginia Commonwealth University, Richmond, VA 23298, USA; [EMAIL_ADDRESS] (K.G.-L.); [EMAIL_ADDRESS] (J.G.D.)  
2 Department of Oral Surgery, Wroclaw Medical University, 50-367 Wroclaw, Poland; [EMAIL_ADDRESS]  
3 Department of General Practice, School of Dentistry, Virginia Commonwealth University, Richmond, VA 23298, USA  
4 Department of Oral and Maxillofacial Surgery, School of Dentistry, Virginia Commonwealth University, Richmond, VA 23298, USA  
5 Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University, Richmond, VA 23298, USA  
6 Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia; [EMAIL_ADDRESS]  
7 Department of Periodontology. Faculty of Medicine, University of Ljubljana, 1000 Ljubljana, Slovenia; [EMAIL_ADDRESS]  
8 Correspondence: [EMAIL_ADDRESS]  
Received: 8 June 2020; Accepted: 22 June 2020; Published: 25 June 2020  
**Featured Application: This work demonstrates that an erbium-doped yttrium aluminum garnet laser (Er:YAG). laser can be used as a non-invasive crown retrieval tool for common all-ceramic crowns. The type of all-ceramic material has a significant impact on crown removal time. However, the cement thickness has less influence on retrieval time or temperature. The temperature increase during laser irradiation does not appear to be harmful or clinically significant.**  
The study examined the effect of noninvasive crown retrieval/reuse process using an erbium-doped yttrium aluminum garnet laser (Er:YAG). Twenty-six extracted human teeth were prepared for a crown. The crown was milled using lithium disilicate (LD) and zirconia (\(Z\)) materials, \(n=13\) per group, with three for scanning electron microscopy (SEM). The crown was luted using composite resin cement and subjected to a laser retrieval process. After the retrieval process, the crown was cleaned, re-cemented and laser-retrieved two more times, without and with additional tooth reduction mimicking clinical refreshment of dentin. Retrieval time and temperature were analyzed using analysis of variance (ANOVA). Surface changes were observed through SEM. The retrieval times were \(267.1\pm 130.43,220\pm 79.09,277.1\pm 126.44,368.4\pm 136.14,355\pm 159.39\), and \(419.2\pm 121.36\) s for first, second, third LD and \(Z\) groups, respectively (\(p=0.009\)). The maximal temperatures were \(23.95.1\pm 1.89\)\({}^{\circ}\)C, \(24.86\pm 2.01\)\({}^{\circ}\)C, \(24.17\pm 1.53\)\({}^{\circ}\)C, \(22.88\pm 1.51\)\({}^{\circ}\)C, \(24.03\pm 1.74\)\({}^{\circ}\)C, and \(21.99\pm 1.32\)\({}^{\circ}\)C for first, second, third LD and \(Z\) groups, respectively (\(p=0.006\)). Er:YAG laser crown removal is an effective retrieval tool for all-ceramic crowns. Minimal changes to teeth and crowns were observed following laser irradiation.  
**Keywords:** Crown removal; Debond; Er:YAG; Laser; Lithium disilicate; Zirconia