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Article in Korean | WPRIM | ID: wpr-719557


PURPOSE: The laser processability of dental prosthesis is investigated using two ceramic composites, including 3M, Lava Ultimate and Ivoclar vivadent, IPS e.max. MATERIALS AND METHODS: The CO₂ laser, picosecond laser and femtosecond laser are used to assess the processing power of dental prosthetic materials Lava Ultimate and IPS e.max and the line processing shape was measured using a confocal microscope. RESULTS: The brittleness, carbonization and micro crack of the ceramic composite were influenced by heat accumulation of the material and could be controlled by the laser power and pulse time. CONCLUSION: In the case of CO₂ lasers, micro crack and carbonation occurred immediately, and in the picosecond laser processing, the micro cracks are partially improved, but the carbonization occurs continuously. Finally, we confirmed the high efficiency of laser processing with femtosecond laser. In particular, Lava Ultimate, a ceramic resin composite material, showed the best processability when processed using a femtosecond laser.

Carbon , Ceramics , Dental Prosthesis , Hot Temperature , Lasers, Gas
Article in Chinese | WPRIM | ID: wpr-806668


Objective@#To observe the efficacy of 755 nm picosecond laser and intense pulsed light in the treatment of facial freckles.@*Methods@#Sixty-six outpatients with freckles were randomly divided into two groups. They were treated with 755 nm picosecond laser (P755 nm) and intense pulsed light (IPL), respectively. Frequent freckles were analyzed before treatment and at 4 week after treatment.@*Results@#Both treatments had good curative effect, but the P755 nm group had better efficacy than the IPL group with significant difference.@*Conclusions@#755 nm picosecond laser and IPL can treat freckles very well, and P755 nm group is superior to IPL.

Annals of Dermatology ; : 779-781, 2017.
Article in English | WPRIM | ID: wpr-225291


The picosecond lasers have shown to effectively treat tattoo pigments that are intractable to previous multiple Q-switched (QS) laser treatments. Therefore we hypothesized that a picosecond laser would show better efficacy with minimal adverse events in the treatment of melasma and post-inflammatory hyperpigmentation (PIH) that are difficult to treat with conventional QS lasers. Two patients with melasma and one patient with PIH were treated with a Picosecond 755-nm Alexandrite Laser (Cyanosure, USA). All patients were Korean with skin type IV and no longer responding to QS laser treatments. Laser treatment was well tolerated in all the patients. Adverse events such as PIH were not reported during 8 weeks of follow up period. After the multiple treatment sessions, one patient reported fair improvement and two patients reported good improvement. Consistent with the clinical results, ex vivo skin model irradiated with a Picosecond 755-nm Alexandrite Laser also showed decreased epidermal keratinocyte necrosis compared with the 532-nm QS Neodymium-Doped Yttrium Aluminium Garnet Laser (Lutronic, Korea) yet decreased melanin content. In conclusion, the Picosecond 755-nm Alexandrite Laser may be useful for effective treatment of intractable melasma and PIH with fewer adverse events in dark Asian skin.

Asians , Follow-Up Studies , Humans , Hyperpigmentation , Keratinocytes , Lasers, Solid-State , Melanins , Melanosis , Necrosis , Skin , Yttrium
Article in Chinese | WPRIM | ID: wpr-489565


Objective To preliminarily select safe parameters for different forms of teeth by irradiating 532 nm picosecond Nd∶YAG laser on human isolated teeth with different irradiation time length and power.Methods Isolated human teeth including anterior teeth,premolars,molars were irradiated with 532 nm picosecond laser.Repeated measurements were made for each tooth by thermometer to measure the temperature of pulp chamber on different time point and power,and the temperature change (△T) was calculated.Results △T of the anterior irradiation group at 0.6 W,30 s;0.8 W,20 s and 30 s;1.0 W,10 s,20s and 30s were more than 5.6 ℃,which was the same with that of premolar group at 1.0 W,30s.△T of the molar group at 1.0 W,30 s was less than 5.6 ℃.Under certain power,the temperature of pulp chamber increased with the prolonging of irradiation time (P<0.05).At a certain time,temperature increased with the power (P<0.05).Conclusions It is safe to carry out operation on the parameters setting of 0.8 W,10 s and 0.6 W,20 s irradiation for anteriors teeth;0.4 W,30 s,0.8W,30 s and 1.0 W,20 s for premolar teeth,and 1 W,30 s for molar teeth.In the application of 532 nm picosecond laser,attention is required to be paid on parameter setting to control input power and irradiation time.