Ultramorphological and histochemical changes after ER,CR:YSGG laser irradiation and two different irrigation regimes

Area of Science:

• Endodontics
• Dental Materials Science
• Laser Dentistry

Background:

• Smear layer removal is crucial for effective endodontic treatment.
• Conventional irrigation methods have limitations in completely removing the smear layer.
• Laser technologies offer potential for improved root canal preparation.

Purpose of the Study:

• To compare the ultramorphological and chemical effects of Er,Cr:YSGG laser irradiation versus two irrigation protocols on radicular dentin.
• To evaluate smear layer removal and potential thermal alterations in dentin treated with different methods.

Main Methods:

• Human premolars were divided into three groups: NaOCl irrigation, Rc-Prep + NaOCl irrigation, and NaOCl irrigation followed by Er,Cr:YSGG laser irradiation.
• Scanning Electron Microscopy (SEM) was used to assess smear layer removal and surface morphology.
• Energy Dispersive X-ray analysis (SEM-EDX) was performed to evaluate chemical composition (Ca/P ratio).

Main Results:

• NaOCl irrigation alone resulted in incomplete smear layer removal.
• Rc-Prep + NaOCl showed moderate to complete smear layer presence with exposed collagen.
• Er,Cr:YSGG laser irradiation achieved partial to total smear layer removal but caused minor thermal effects like carbonization and melting.
• No significant differences in Ca/P ratios were observed across groups.

Conclusions:

• Er,Cr:YSGG laser irradiation is effective in removing the smear layer from radicular dentin.
• While effective, laser treatment requires careful parameter control to minimize thermal damage.
• Neither laser nor chemical irrigation alone completely optimizes smear layer removal without potential drawbacks.