Ultra-structural changes at the apical stop irradiated with CO2 laser.

Area of Science:

• Endodontics
• Dental materials science
• Laser dentistry

Background:

• CO(2) laser applications in endodontics are often evaluated post-apical resection.
• Limited data exists on laser-induced ultra-structural changes during root canal preparation.

Purpose of the Study:

• To evaluate ultra-structural dentine changes at the apical stop following CO(2) laser irradiation during biomechanical preparation.
• To assess the impact of different laser potencies on dentine morphology.

Main Methods:

• Sixty human canine teeth underwent biomechanical preparation with Largo burs.
• Apical stops were created at 1 mm and 2 mm from the apex.
• Specimens were irradiated with CO(2) laser at 3W or 5W potency and analyzed via scanning electron microscopy.

Main Results:

• Increased laser potency from 3W to 5W resulted in more intense ultra-structural changes (p < 0.0001).
• Changes ranged from smear layer removal to significant dentine fusion.
• No significant difference in ultra-structural changes was observed between 1 mm and 2 mm apical stop distances for the same laser potency.

Conclusions:

• CO(2) laser irradiation at 5W potency induces extensive dentine fusion, effectively sealing the apical foramen.
• Laser potency is a critical factor influencing ultra-structural changes in dentine during endodontic preparation.