Selective preparation of hard dental tissue - Classical and laser treatments comparison

For the purpose of micro-selective preparation which is a part of the modern dentistry, four various methods were examined: a removal of tissue by Er: YAG laser radiation (laser is working in free-running or Q-switching regime), preparation of tissues by ultrasonic round ball tip, and by the classical dental drilling machine using diamond round bur. In the case of laser application, 40 mJ of interaction energy in pulse 200 μs long yielding to the interaction intensity 62 kW/cm², and 20 mJ in 100 ns long pulse yielding to the interaction intensity 62 MW/cm² was used for the case of free running, and Q-switch regime, respectively. For comparisson with the classical methods the ultrasound preparation tip (Sonixflex cariex TC, D - Sonicsys micro) and dental driller together with usual preparation burrs and standard handpiece were used. For the interaction experiment the samples of extracted human teeth and ebony cut into longitudinal sections and polished were used. The thickness of the prepared samples ranged from 5 to 7 mm. The methods were compared from the point of prepared cavity shape (SEM), inner surface, and possibility of selective removal of carries. The composite filling material was used to reconstruct the cavities.