Laser Photocoagulation : Literature Review

The increasing role in the use of lasers for medicinal purposes has had an impact on advances in medicine. Laser photocoagulation is a therapy that is widely used for retinal diseases. The invention of lasers revolutionized retinal therapy by facilitating more precise, reliable applications and minimal pain. Based on single wavelength selection, the laser also reduces the amount of damage to adjacent tissue. In the field of medicine other than as curative therapy, laser photocoagulation is also carried out as a preventive measure, preventing the occurrence of more serious complications in these patients. At present, laser photocoagulation as a preventive therapy uses argon laser as its main ingredient. Argon lasers are lasers with green light. The purpose of this burning is to repair diseased or damaged eye tissue so that it can prevent complications that will be caused by persistent diseased or damaged tissue.

The effect of a light source with reduced irradiance on the marginal seal in class V cavities

Introduction: During composite polymerisation, material contraction occurs and leads to microgap formation. Various light sources are used in everyday dental practice for the polymerisation of composite restorations: conventional halogen, xenon, LED light curing units (LCUs) and argon lasers. Aim: The aim of this study was to analyze the effect of an LED LCU with reduced irradiance on the marginal seal of different composite restorations. Material and Method: The study was conducted on 40 extracted human teeth (intact and carious). Class V cavities were prepared on all teeth. Cavities were filled with either Filtek Supreme -3M (20 teeth) or Luksogal - Galenika (20 teeth) and polymerisation was done using an LED source with reduced irradiance (90 mW/cm2). Microleakage was tested using the dye penetration method with silver nitrate. Dye penetration was assessed using a stereo loupe with a microscale and x6 magnification. Results: The obtained results suggested that greater dye penetration occurred in samples restored with Luksogal. There was a statistically significant difference between occlusal (27.00) and gingival (36.90) margins (p<0.05). Dye penetration was observed in all intact and carious teeth restored with Filtek Supreme on both gingival and occlusal margins. A statistically significant difference was observed between gingival (22.90) and occlusal (15.50) margins (p<0.01). Conclusion: Microgaps were observed in all teeth irrespective of the type of composite material used for restoration.

Investigation of Laser-Induced Etching of Ti in Phosphoric Acid

ABSTRACTLaser-induced chemical etching of Ti in phosphoric acid has been investigated using cw Nd:YAG (1.064 μιm) and Argon lasers (514 nm) operating in the fundamental Gaussian mode. Two different regions of etching were observed, which are separated by a characteristic threshold value of the laser power and ascribed to melting of the metal. Below the threshold an exponential dependence of etch rates on laser power suggest a thermally activated etching mechanism. Time-resolved measurements indicate in this region the dissolution of the passivation layer followed by surface etching of the metal grains. After laser illumination an immediate repassivation of the re-cooled surface stops the etch reaction.