Investigation of Composite Removal by Er,Cr:YSGG Laser vs Rotary Instruments

Objectives: Complete removal of existing composite restoration without unnecessary removal of sound tooth tissue is challenging. This study compared the amount of tooth structure removed and composite remaining in Class III cavities after removal of restorations with an erbium laser or a rotary instrument.
Methods: Mesiolingual and distolingual cavities were prepared in 12 extracted anterior teeth (IRB#17-05324-NHSR), restored with shade-matched composite, finished and polished. One of the two restorations was removed using a rotary instrument (handpiece and carbide burs), while the other restoration was removed using the Er,Cr:YSGG laser. Dental stone models were made from polyvinyl siloxane impressions at all stages and scanned with a 3D optical scanner. Subsequent scans were precisely aligned using Cumulus software, and the amount of removed tooth structure and residual composite were calculated. Differences between the bur and laser removal were compared using t-test.
Results: Rotary instrumentation left significantly more composite than the laser in terms of average thickness, maximum thickness, volume, and area (p=0.006 to 0.04). The rotary instrument removed significantly more tooth structure than the laser in terms of average depth (p=0.0017), but not maximum depth (p=0.0762). The area of tooth loss was significantly larger (p=0.0004) in the laser group because in the bur group composites were not completely removed.
Conclusions: Er,Cr:YSGG laser was more effective in removing existing composite restorations than a rotary instrument. A rotary instrument has the potential to remove more tooth structure than the laser.