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Tooth and Implant-supported Crown Removal with Er:Yag-laser: A Pilot Study
Purpose: Since removal of a resin-luted all-ceramic restoration is a challenge, the use of lasers becomes very popular, nowadays. Thus, for removal of orthodontic bracelets and laminate veneers, Er:Yag lasers are commonly used. However, removal of resin-luted all-ceramic crowns -whether tooth or implant supported- with lasers is still confusing due to its effectiveness and effects on abutment underneath. This pilot study was aimed to examine laser heat transmission to the vital tissues during Er:Yag laser application in appropriate removal time of implant and tooth supported crowns.
Materials and methods: Three samples, prepared for testing were respectively; tooth-supported lithium-disilicate (E.maxCAD; Ivoclar-Vivadent, Liechtenstein), implant-supported zirconia on titanium, implant-supported lithium-disilicate on zirconia abutment. Samples were designed as maxillary first premolar and tooth reduction was made in similar sizes of implant-supported titanium and zirconia abutments, with chamfer finish-line. Crown thicknesses were standardized as; margin:1 mm, axial/proximal:1.5 mm and occlusal:2 mm. Lithium-disilicate crowns were luted with resin (Variolink EstheticDC; Ivoclar-Vivadent, Liechtenstein), zirconia crown was luted with zinc-polycarboxylate cement (Pentron; SpofaDental, Czech Republic). Er:YAG laser (Fotona; Stegne7, Ljublja, Slovenia) was used for removing crowns. Laser were applied to implant supported crown with parameters; 4.5W, 15 Hz, 300 mJ,10mm in distance, air/water spray at 2/2 with noncontact mode, until removal. Laser parameters changed to 5 W,10 Hz, 500 mJ for tooth supported crown. Heat transmission values on tooth and implant abutments, and, removal time were measured for each sample.
Results: Lithium-disilicate crown on tooth was removed in 2:40 (min:sec) and temperature change was observed as 4.2 degrees. Lithium-disilicate crown on zirconia abutment removed in 4:40 and temperature change was observed as 2.8 degrees. Zirconium crown which is cemented with zinc-polycarboxylate cement on titanium abutment can not be removed.
Conclusion: In this pilot study, it was observed that using laser for removing crowns is safe.
Keywords: All-ceramic, Er:Yag laser, heat transmission, implant, removal time.