ABSTRACT
Introduction: The aim of this study was to evaluate the composite surface treated by different powers of Erbium-Doped Yttrium Aluminum Garnet [Er:YAG] laser in comparison with bur preparation via scanning electron microscope. Methods: Fourteen composite resin blocks with 15× 10 × 10 mm dimensions were used in this study. The samples were divided to seven groups as follow: Group 1 [power: 1 W, Energy: 50 m/l]; Group 2 [power: 2 W, Energy: 100 m/l]; Group 3 [power: 3W, Energy: 150 m/l]; Group 4 [power: 4 W, Energy: 200 m/l]; Group 5 [power: 5W, Energy: 250 m/l]; Group 6 [power: 6 W, Energy: 300 m/l]; Group 7: Diamond bur. Then, the samples were prepared for SEM examination. Results: The surface treated by Er:YAG laser showed irregular and micro porous surface. Conclusion: It seems that composite surface treatment by Er:YAG laser can be an alternative method for composite repair if suitable parameters are used
ABSTRACT
Indirect composites are designed to overcome the shortcomings of direct composites such as polymerization shrinkage and low degree of conversion. But, good adhesion of resin cements to indirect composites is still difficult. This research was designed to assess the effect of different powers of Er;YAG laser compared with sandblasting. On the micro tensil bond strength of resin cement to indirect composites. Specimens were prepred using dental resin composite [Gradia GC] and metallic mold [15×5×5 mm] and were cured according to the manufacturer's instructions. 24 blocks were prepared and randomly divided into 12 groups. G1:no treatment [as control], G 2-6: Er; YAG laser irradiation [2, 3, 4, 5, 6 Watt], G7: sandblast. Two composite blocks were bonded to each other with Panavia F.2. resin cement. The cylindrical sections with dimensions of 1 mm were tested in a microtensile bond strength tester device using 0.5 mm/min speed until fracture points. Data were analyzed using 2-way ANOVA and T-test. Interaction between lasers irradiation and sandblast treatments were significant [P<0.05]. Thus, T-test was used for comparing laser groups. T-test showed that when using laser with energies less than 150 mJ, there was no significant difference [P>0.05] whether samples were sandblasted or not. Samples which received 300 mJ of laser showed lower bond strength compared with no laser treatment. Other groups showed no significant difference [P>0.05]. It seems that application of sandblast with proper variables, is a good way to improve bond strength. Laser application had no influence in improving the bond strength between the indirect composite and resin cement
ABSTRACT
Indirect composites are developed to overcome the shortcomings of direct composites but, the adhesion of resin cements to indirect composites is still difficult. The purpose of this study was to evaluate the surface morphology of indirect resin composite treated by different powers of Er:YAG laser using Scanning Electron Microscopy [SEM]. Indirect resin composite blocks [GC Gradia DA2, Japan] with 15× 10 × 10 mm dimensions were made according to manufacturer's instructions [n=7]. The bonding surface of these blocks were polished, then the samples were divided to seven groups as follow: Erbium-Doped Yttrium Aluminum Garnet [Er:YAG]laser with output power of 2, 3, 4, 5, 6,7 W [frequency of 20 Hz, very short pulse] and no treatment. Then, the surfaces were evaluated by scanning electron microscope. The surface treated by Er:YAG laser showed a porous surface. But the amount and pattern of these irregularities differ in each group which may produce micromechanical retention compared to control group with no treatment. Er:YAG laser can be used as an alternative technique for surface treatment and roughening of indirect resin composites
ABSTRACT
The aim of this study was to investigate the morphological changes of human dentin after Erbium-Doped Yttrium Aluminum Garnet [Er:YAG], Carbon Dioxide [CO[2]] laser-irradiation and acid-etching by means of scanning electron microscopic [SEM]. 9 extracted human third molars were used in this study. The teeth were divided in three groups: first group, CO[2] laser with power of 1.5 w and frequency of 80 Hz; second group, Er:YAG laser with output power of 1.5 W frequency of 10 Hz, very short pulse with water and air spray was applied; and third group, samples were prepared by acid-etching 37% for 15 sec and rinsed with air-water spray for 20 sec. Then, the samples were prepared for SEM examination. Melting and cracks can be observed in CO[2] laser but in Er:YAG laser cleaned ablated surfaces and exposed dentinal tubules, without smear layer was seen.. It can be concluded that Er:YAG laser can be an alternative technique for surface treatment and can be considered as safe as the conventional methods. But CO[2] laser has some thermal side effects which make this device unsuitable for this purpose
ABSTRACT
The aim of this study was to evaluate and compare the Scanning electron microscope [SEM] of indirect composite conditioned by Erbium-Doped Yttrium Aluminum Garnet [Er:YAG] laser, Neodymium-Doped Yttrium Aluminium Garnet [Nd:YAG] laser and Carbon Dioxide [CO[2]] laser. 18 indirect composite blocks [GC Gradia DA2, Japan] with 15 x 10 x 10 mm dimensions were made. The bonding surface of these blocks were polished, then the samples were divided into six groups as follow: Er:YAG laser with output power of 0.5 W and frequency of 10 Hz, Nd:YAG laser with output power of 0.25, 0.5 W and frequency of 10 Hz, CO[2] laser with output power of 0.5 W and frequency of 10 Hz and 5 Hz, and no treatment. Then, the surfaces were evaluated by SEM. Irregularities were observed in Er:YAG laser samples compared to control group that produced suitable retention for adhesion of cements. Nd:YAG and CO[2] lasers showed melting areas. Among different lasers, Er:YAG laser can be used as an alternative technique for surface treatment of indirect composites
ABSTRACT
Failure of bonding between artificial teeth and denture base material is a considerable problem for patients who wear dentures. According to the different impact of artificial teeth and different information about resistance force of mastication and also with deficiency in researchs, this study was designed to compare the bond strength of composite and acrylic artificial teeth to auto-polymerized denture base resins with and without cyclic loading. In this experimental and in vitro study, an acrylic resin auto-polymerized [Rapid Repair, Dentsply] and four artificial teeth [Acrylic Marjan new, Composite Glamour teeth and Ivoclar acrylic and composite teeth] were used. Therefore, 8 groups of 10 specimens each were evaluated. All specimens were thermocycled for 5000 cycles, in water baths between 5 and 55[degree]C. Half the specimens in each group were treated with cyclic loading at 50N for 14, 400 cycles at 1.2 Hz. The shear bond strengths were measured using a Universal Testing Machine. Data were analyzed using Two-way ANOVA test. Statistical analysis demonstrated no significant effect of cyclic loading on the shear bond strength, but the type of artificial tooth affected the shear bond strength [P=0.006]. Also, the interaction between Cyclic loading and the type of artificial tooth showed no significant difference [P=0.98]. Tukey test showed that acrylic teeth [Ivoclar] had statistically higher bond strength values than that of other teeth [P[Glamour]=0.02], [P[Composite ivoclar]=0.01] and [P[Marjan new]=0.02]. Within the limitation of this study, the predominant type of fracture in all groups was cohesive, therefore the bond strength was adequate in all teeth and the type of artificial tooth may influence the bond strength of denture teeth to denture base resin. Cyclic loading had no significant effect on the bond strength of denture teeth to the auto-polymerized acrylic resin.
Subject(s)
Denture Bases , Acrylic Resins , Tooth, Artificial , Shear StrengthABSTRACT
The aim of this study was to investigate the Scanning Electron Microscope [SEM] analysis of tooth surface irradiated by different parameters of Er:YAG laser. 15 caries-free extracted human third molars were used in this study. The teeth were put into 5 groups for laser irradiation as follows: Group 1 [power: 2.5 W, Energy: 250 mJ]; Group 2[power: 3 W, Energy: 300 mJ]; Group 3 [power: 3.5 W, Energy: 350 mJ]; Group 4 [power: 4 W, Energy: 400 mJ]; Group 5 [power: 4.5 W, Energy: 450 mJ]. All samples were prepared by repetition rate of 10 Hz. Then, the samples were prepared for SEM examination. The SEM images showed cleaned ablated surface and exposed dentinal tubules, without production of smear layer. It can be concluded that Er:YAG laser can be an alternative technique for surface treatment and can be considered as safe as the conventional methods, like turbine and bur
ABSTRACT
Reliable bonding between tooth substrate and zirconia-based ceramic restorations is always of great importance. The laser might be useful for treatment of ceramic surfaces. The aim of the present study was to investigate the effect of laser irradiation on the shear bond strength of zirconia ceramic surface to dentin. In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer A12O3, CO[2] laser, or Nd:YAG laser in each test groups. After that, the specimens were cemented to human dentin with resin cement. The shear bond strength of ceramics to dentin was determined and failure mode of each specimen was analyzed by stereo-microscope and SEM investigations. The data were statistically analyzed by one-way analysis of variance and Tukey multiple comparisons. The surface morphology of one specimen from each group was investigated under SEM. The mean shear bond strength of zirconia ceramic to dentin was 7.79 +/- 3.03, 9.85 +/- 4.69, 14.92 +/- 4.48 MPa for CO[2] irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO[2] [P=0.001] and Nd:YAG laser [P=0.017] irradiated specimens with sandblasted specimens. No significant differences were observed between two laser methods [P=0.47]. The mode of bond failure was predominantly adhesive in test groups [CO[2] irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting:41.7%]. Under the limitations of the present study, surface treatment of zirconia ceramics using CO[2] and Nd:YAG lasers was not able to produce adequate bond strength with dentin surfaces in comparison to sandblasting technique. Therefore, the use of lasers with the mentioned parameters may not be recommended for the surface treatment of Cercon ceramics
Subject(s)
Humans , Shear Strength , Dental Bonding , Zirconium , Ceramics , Dentin , Lasers, Solid-State , Lasers, GasABSTRACT
Definitive treatment of oral leukoplakia is very important because of its recurrences and malignant transformation depending on the location, clinical feature, degree of dysplasia and etiological factors. There are different kinds of treatment for this lesion, but using high power laser has some advantages like less pain, swelling, prevention of metastasis, edema, less bleeding [dry surgery] and infection. A 53 year old man with leukoplakia lesion with moderate dysplasia on the left side of the ventral surface of the tongue was selected for treatment with CO[2] laser. The average power is set on 6.2 W with frequency of 20 Hz. The irradiation mode was non-contact. The entire lesion evaporated by the laser with a 2 mm safety margin. In this case, 80% of lesion had disappeared after 5 weeks and the 20% residual was evaporated again with the same parameters than the first time. No significant clinical differences were seen between the normal and laser-treated tissue. Using laser in the treatment of oral lesions has many advantages like selective removal of the affected tissues and minimal damage to surrounding tissue, leading to excellent wound healing with no or minimal scar and good functional results