Showing 7 results for Yag Laser
A. Kowsari , B. Seraj , N. Pasdar ,
Volume 15, Issue 1 (3-2002)
Abstract
Due to the differences in the composite and morphology of dentin in primary and permanent teeth, it is necessary to make improvements in bonding techniques to promote the strength of composite resins bonded to the dentinal surface, in primary teeth. The use of lower radiation, to make structural and chemical changes in dentinal surfaces has been investigated. This research was conducted to evaluate the shear strength of the composite bonded to primary teeth dentin after Nd: YAG laser radiation and acid etching for conditioning. Peripheral dentin of the buccal and lingua! surfaces of 60 extracted posterior primary teeth were exposed and polished with 600 grit with Sic paper. The teeth were divided randomly in 3 groups of 20 teeth. In group 1 etching gel, primer and adhesive of scotch bond multipurpose system (SMP), in group 2 laser at 1.6 w and 80 mj/pulse, and in group 3 laser at 2 s and 700 mj/pulse were used. Moreover, in groups 2 and 3, after laser radiation, acid etching, primer and adhesive of SMP system were applied. After necessary laboratory tests, the mean shear bond strength in MPa were 20.99±5.3 (group 1), 23.82±6.31 (group 2) and 26.58±5.59 (group 3). ANOVA, scheffe, tukey statistical tests showed that the bond strengths of group 3 were statistically higher than group 1. The frequency of dentin cohesive failures were significantly higher in groups 2 and 3, compared to group 1 that indicates a higher bond strength in these groups. Scanning electron mirographs of laser radiated surfaces, show a porous and rough surface morphology that enhances the mechanical bond of the composite.
Mansure Mirzaee, Esmaeel Yassini, Sima Shahabi, Nasim Chiniforoush, Naznin Zeinab Garshasbzade,
Volume 27, Issue 1 (4-2014)
Abstract
Background and Aims: 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 ErYAG laser compared with sandblasting. On the micro tensil bond strength of resin cement to indirect composites.
Materials and Methods: 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.
Results: 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).
Conclusion: 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.
Masumeh Hasani Tabatabaei, Sakineh Arami, Fatemeh Khajavi, Zohreh Moradi,
Volume 29, Issue 4 (1-2017)
Abstract
Background and Aims: Despite the reduction of incidence of dental caries in recent years, this disease is common and many efforts were conducted to decrease the prevalence of dental caries. On the other hand secondary caries lesions are the main reason for replacement of direct restorations. Therefore, the aim of the current study was to evaluate suitable methods of preparation and restorative materials to reduce caries recurrence.
Materials and Methods: In this experimental study, eighty human teeth were collected and stored in normal saline. The teeth were soft-tissue debrided and cleaned with water/pumice slurry and rubber cups in a low-speed handpiece. Speciments were randomly divided in two main groups. Cavities were prepared with diamond burs or Er:YAG laser (10 Hz, 300 mJ, 3W). Each group was divided into 4 sub-groups, and restored with a glass-ionomer cement (Fuji IX), resin modified glass-ionomer (Fuji II LC), total etch bonding + composite resin or self-etch bonding + composite resin. The specimens were submitted to pH cycling. Speciments were then sectioned, polished and Vickers microhardness measurements were performed on each specimen. Differences among the medians were analyzed using two way ANOVA test at a 95% confidence level and Tukey test.
Results: Statistical analysis showed significant difference in the type of substrate (enamel, dentin) in both main groups (P<0.0001) but no differences in the caries lesion development between the cavities restored with the same material and prepared with diamond burs or Er:YAG laser.
Conclusion: The Er:YAG laser used for cavity preparation and different types of restorative materials used did not show the ability to guarantee significantly more acid-resistance tooth structure against demineralization.
Alireza Daneshkazemi, Abdolrahim Davari, Motahareh Amiri, Fatemeh Mirhosseini,
Volume 33, Issue 1 (7-2020)
Abstract
Background and Aims: Erosion is the chemical dissolution of a tooth by acid without bacterial involvement. The purpose of the current study was to investigate the effect of resin infiltration (Icon), MI paste plus, and Nd:YAG laser on the enamel microhardness.
Materials and Methods: 40 enamel samples were obtained from the third molar tooth. Primary microhardness was measured in all specimens. Then, erosion was created using hydrochloride acid on the surfaces of enamel and the microhardness values were measured. The samples were randomly divided into four groups. G1: MI paste plus, G2: MI paste plus+ Nd:YA laser, G3: ICON without etching, G4: ICON with etching. Erosion was induced again by hydrochloric acid and then subjected to thermocycling. Finally, the microhardness of the samples was measured. Statistical analysis was performed using SPSS23 software, one-way ANOVA, multiple Tukey and T-test comparisons. P<0.05 was considered as a significant level.
Results: The microhardness increased in the third stage compared to the second stage in all groups, which was statistically significant (P<0.000). Also, the comparison of the increase of microhardness among groups, except second group with the fourth group, was statistically significant.
Conclusion: All the materials used in this study significantly increased the microhardness of the eroded enamel.
Abdolrahim Davari, Farnaz Farahat, Sanaz Abbasi,
Volume 34, Issue 0 (5-2021)
Abstract
Background and Aims: Restoration of non-carious cervical lesions (NCCLs) is challenging due to the difficulty of adhesion of dental tissues. The aim of this study was to investigate the effects of three methods of surface treatments using diamond bur, Er: YAG laser and sandblasting on the microtensile bond strength of resin composite to the noncarious dentin in cervical lesions.
Materials and Methods: In this in vitro study, 48 canine and premolar extracted human teeth with NCCLs at the buccal surface were selected and randomly divided into 4 groups of twelve each: control group without any treatment, Er: YAG laser group, diamond bur group and sandblasting group. For all groups, the bonding agent used was Clearfil SE Bond and then the cavities were filled with
the Filtek Z250 resin-composite. After this step, the teeth were cut and then subjected to the microtensile bond strength test. Data were analyzed by the Kruskal Wallis test.
Results: According to the obtained results, the microtensile bond strength, from the highest to the lowest values were in the sandblast group (24.57±10.24 MPa), the diamond bur group (19.19±10.8 MPa), laser group (18.59±9.05 MPa) and the control group (18.56±9.27 MPa), respectively. Although, no statistically significant difference was found between any of the groups (P=0.266).
Conclusion: It seems that in teeth with NCCLs, the sandblasting method had a much better effect on the bond strength, although no statistically difference between surface treatment methods was found.
Abdolrahim Davari, Farnaz Farahat, Mahnaz Mehranfar,
Volume 35, Issue 0 (5-2022)
Abstract
Background and Aims: Recently, the addition of nanoparticles into the restorative materials and tooth preparation by laser for improving the bond strength have been concidered by researchers. The aim of this study was to investigate the shear bond strength of the bioactive glass ionomer containing titanium particles and a conventional glass ionomer with two surface treatments by Er-YAG laser and conventional methods.
Materials and Methods: In this in-vitro study, 64 sound extracted premolars were collected. For conventional method, the specimens were prepared in such a way that dentin surfaces with a depth of 0.5 millimeter created at distance of 2 mm from the joint of CEJ at the root or crown. In the laser group, after preparing the teeth, the surface area was prepared by Er-YAG laser. Then, in the middle part of the buccal surface, a cylindrical mold with dimensions of 3.5 mm in diameter and 4 mm in height was placed and for each group was filled with its own glass ionomers. The specimens were divided into 8 groups by simple random sampling (n=8): A (laser, conventional glass ionomer, coronal dentin)/ B (laser, glass ionomer containing titanium nanoparticle, coronal dentin)/C (conventional, conventional glass ionomer, coronal dentin)/ D (conventional, glass ionomer containing titanium nanoparticle, coronal dentin)/ E (laser, conventional glass ionomer, root dentin)/ F (laser, glass ionomer containing titanium nanoparticle, root dentin)/ G (conventional, conventional glass ionomer, root dentin)/ H (conventional, glass ionomer containing titanium nanoparticle, coronal dentin). Finally, the shear bong strength by a universal testing machine was measured at a cross-head speed of 1 mm/min. For data analysis, Two-way ANOVA test was used to evaluate the effect of each variable and their interaction on the shear bond strength and Tukey test was used to compare the two groups.
Results: There was significant difference only between groups B with C (P=0.002), E (P=0.007), G (P=0.001) and H (P=0.01). The highest bond strength was found for group B (laser, glass ionomer containing titanium nanoparticle, coronal dentin) and the lowest bond strength for group G (conventional, conventional glass ionomer, root dentin).
Conclusion: All three factors of Er-YAG laser, glass ionomer containing titanium nanoparticle and coronal dentin had a positive effect on the improvement of the bond strength.
Elahe Soltanmohamadi Borujeni, Ali Bavi, Mohammad Aghaali, Ali Saleh, Aida Mehdipour,
Volume 37, Issue 0 (3-2024)
Abstract
Background and Aims: Strong bond between the ceramic brackets and ceramic veneers has an important role in cosmetic treatment. The purpose of this study was to investigate the effect of aging on the shear bond strength (SBS) of ceramic brackets bonded to zirconia after surface preparation by Neodymium-doped Yttrium Aluminum Garnet (Nd: YAG) laser or sandblasting with alumina.
Materials and Methods: This experimental study was conducted on 24 zirconia blocks and these blocks were randomly divided into two groups for surface preparation and each was sub-divided into three time intervals. Surface preparation was done by sandblasting with alumina: in SG1 (Immediately after sandblasting), SG2 (2 weeks after sandblasting), and SG3 (3 months after sandblasting) groups. For the Nd: YAG laser (1/5W, 20Hz, 10s) with non-contact mode: in LG4 (Immediately after laser), LG5 (2 weeks after laser), and LG6 (3 months after laser) groups. The ceramic brackets were bonded to the zirconia blocks. The SBS and adhesive remnant index (ARI) were evaluated and compared among test groups. Dara were analyzed using Mann Whitney test.
Results: There was no significant difference between the SBS of SG1 and LG4 (P=0.430), SG2 and LG5 (P=0.382) and SG3 and LG6 (P=0.326) groups. LG4 group showed the highest shear bond strength. After aging (2 weeks and 3 months), the laser groups showed higher SBS. There was no significant difference in the ARI between SG1 and LG4 (P=0.220), SG2 and LG5 (P=0.154), SG3 and LG6 (P=0.527) groups.
Conclusion: No significant difference was observed between the Nd: YAG laser and sandblasted groups in terms of SBS and ARI over time. Therefore, Nd: YAG laser could be used as a surface treamnet method in Zirconia crowns for bonding to ceramic brackets.
