Lasers in operative dentisry and endodontics/ dental implant courses by Indian dental academy

33 DP-bioactive glass paste and enamel/dentin when they are subjected to CO 2 laser. They examined the changes of laser-exposed DP-bioactive glass paste by means of X-ray diffractometer (XRD), Fourier transforming infrared spectroscopy (FTIR), differential thermal analysis/thermo gravimetric analysis (DTA/TGA), and scanning electron microscopy (SEM). From the study, they found that the temperature increase due to laser irradiation was greater than 900 degrees C and that the DP-bioactive glass paste could be melted in a short period of time after irradiation. In the study, they successfully developed a DP-bioactive glass paste, which could form a melting glass within seconds after exposure to a medium energy density continuous-wave CO 2 laser.

The paste will be used in the near future to bridge the enamel or dentin surface crack by the continuous-wave CO2 laser.Lin, C.P., Lee, B.S. et al (2001)63 attempted to use lasers to fuse a low melting-point bioactive glass to fractured dentin. This report is focused on the phase, compositional, and morphological changes observed by means of X-ray diffractometer, Fourier transforming infrared spectroscopy, and scanning electron microscopy-energy depressive X-ray spectroscopy in human dentin after exposure to Nd: YAG laser. The irradiation energies were from 150 mJ/ pulse-10 pps-4 s to 150 mJ/pulse-30 pps-4 s. Based on the results the irradiation energy of Nd: YAG laser used to fuse a low melting-point bioactive glass to dentin is 150 mJ/ pulse-10 pps-4 s.

Prevention Of Microleakage Of Retrograde Root Canal Filling Micro leakage of retrograde root canal fillings is one cause of failure of apicoectomies. Although the improvement of canal sealers, root canal filling techniques, and application of calcium hydroxide paste as root canal medication are recommended to prevent microleakage, there is still no ideal method. The author and coworkers have been studying ways to solve these problems using lasers, and a decrease of microleakage at apicoectomy was confirmed in vitro. The closure of exposed dentinal tubules on the cut surface at the root end was observed by scanning electron microscopy. Pulsed Nd: YAG and CO 2 lasers are recommended at 1 to 2 W under air-cooling in combination with 38% silver ammonium solution. The root end cavity must be filled using cement or resin after thorough cleaning. The application of Nd: YAG laser to tooth surface can change its surface permeability. The purpose of a study by Stabholz, A., Khayat, A., et al (1992)102 was to investigate the effects of Nd: YAG laser on the permeability of dentin following apicoectomy and retrofill. The amount of dye penetration was significantly lower in lased roots than in non-lased ones (p < 0.05). Based on their results, it appears that application of Nd: YAG laser reduces the permeability of resected roots.An in- vitro study was done to compare the apical seals achieved using retrograde amalgam fillings or the Nd: YAG laser by Wong, W.S., Rosenberg, P.A., et al (1994) 120. They concluded that no statistically significant difference was found in bacterial leakage between the laser-treated group and the retrograde amalgam group. Sealing the root apex during apical surgery is important for a successful outcome. The effect of XeCl-308 nm excimer laser irradiation on the fusion and seal of hydroxyapatite to the root apex was tested in extracted human teeth by Mor, C., Stabholz, A., et al (1995) 76.Twenty-four roots of intact single-rooted premolars were instrumented to size 30 K-file at the apex leaving a patent apical foramen. The apex of each tooth was covered with a freshly prepared paste of hydroxyapatite powder mixed with saline. The samples were then divided into two groups. In 12 teeth, the apical area was irradiated with XeCl-308 nm excimer laser at a fluence of 0.7 J/cm2 for 5 s with pulse repetition rate of 25 Hz and a spot size of 0.13 cm2 immediately after the hydroxyapatite application. In the other 12 teeth, no laser treatment was performed after the hydroxyapatite application. The roots were mounted on a model for the detection of radicular leakage of hydrogen peroxide.