Showing 22 results for Laser
N. Takzaree , K. yarmohammadi , Ar. Takzaree , H. semiyari. , M. Akbari ,
Volume 14, Issue 4 (1-2002)
Abstract
Pain reduction and surgical wound healing enhancement have several advantages. Wound healing is a complex and organized phenomenon. During this phenomenon, definite and harmonized processes such as: reconstruction, immigration parenchyma and connective tissue cells proliferation and re-construction of gingival connective tissue take place. Studies show that lower power laser (He-Ne) can induce different biological changes in ceils through biochemical mechanisms. Considering the therapeutic effects of (He-Ne) low power laser radiation on healing processes, cell proliferation, connective tissue fibers and finally the acceleration of gingival wound healing were studied. This study was done on 50 mature and healthy rats with the average weight of 250 to 300 grams, and 3 to 4 months old. After anesthesia, maxillary wounds, with the same size, were made in all samples and they were randomly divided into control and test groups. After surgery, rats of test group received laser radiation with the value of 5 mJ/cm3 every day for a period of 5 days. And on the 5lh day, they were killed. Gingival biopsy was performed and histological study was done. The number of fibroblasts, collagens, endothelial ceils and blood vessels were counted. In test group, the granulation tissue was more active and the edema and inflammation were lesser than those of the control group. Data were analyzed by t-test method and PO.05 was significant. So, it is concluded that periodical radiation of (He-Ne) low power laser has an important role on surgical gingival wounds.
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.
M. Sahebjamei , A. azizi , F. Jamali , N. Marofi ,
Volume 15, Issue 1 (3-2002)
Abstract
Muscular pain is one of the most common causes for facial pain. Myofacial pain dysfunction syndrome (MPDS) is one of the most important disorders of facial area that affected patients suffer from pain, tenderness of one or more masticatory muscles and limitation of movements. Lack of specific and effective therapeutic method, makes it necessary to find a treatment to decrease pain. Considering the analgesic and anti- inflammatory effects of low-level laser, some investigators have recommended it for MPDS patient's treatment. In this study, the effects of low level laser (Ga-Al-As) on MPDS patients referred to dental faculty of Tehran University of Medical Sciences, were investigated. Twenty- two MPDS patents, with mean age 33.32 years, were treated for 4 weeks (12 visits). Clinical examinations were performed in 6 stages. The results of this study showed that variables such as pain severity, cheek pain, pain frequency and tenderness of masseter, temporal, internal and external pterygoid muscles, had a statistically significant improvement at the end of treatment with low level laser (GA-A1-AS) which lasted for three months, (follow- up period). Results of this study showed that, low-level laser therapy has a sedative effect on the pain and tenderness of masticatory muscles in MPDS. Patients and having an accurate and regular program to complete treatment period, has an important role in MPDS improvement.
T. Jafarzadeh , M. erfan , Dc. Watts , A. Cash ,
Volume 15, Issue 2 (5-2002)
Abstract
Dentine bonding systems are usually unfilled, and so their shrinkage may be significant. High shrinkage may cause internal stress at the interface between resin-composite restoration and the dentine substrate. Failure of the adhesive interface may be observed due to the interna! stress. The aims of this study were:A) To obtain a suitable method for measuring the kinetics of polymerisation shrinkage in unfilled resm at different thicknesses, particularly for thin films.B) Consideraing the effect of thickness on shrinkage.Scotchbond Multipurpose (3M) adhesive bond resin was used. To overcome the particular challenges presented by thin films, a filled-ring measurement procedure was used. Also, a non-contact laser analogue displacement sensor system was developed and applied to measure polymerisation shrinkage. Regression analysis was performed on a complete data set. Non-linear regression analysis established a logarithmic relationship between polymerisation shrinkage and layer thickness. The method applied in this study was found to be sensitive and accurate procedure for determining photo-polymerisation shrinkage of thin films. Polymerisation shrinkage increased with logarithmic of the adhesive thickness.
H. Razmi, N. Shokouhinejad, R. Fekrazad , P. Motahhary, M Alidoust,
Volume 22, Issue 4 (1-2010)
Abstract
Background and Aims: Considering advantages and disadvantages of mineral trioxide aggregate (MTA), Calcium Enriched Mixture (CEM) cement has been developed recently. The purpose of this study was to compare the apical microleakage of the root-end cavities prepared by ultrasonic or Er,Cr:YSGG laser and filled with MTA or CEM cement.
Materials and Methods: Eighty single-rooted, extracted human teeth were instrumented and obturated. Root-end resection was made by removing 3 mm of the apex. The teeth were randomly divided into two experimental (n=30) and two positive and negative control (n=10) groups. After that, the retrograde cavities were prepared using ultrasonic or Er,Cr: YSGG Laser. According to the root-end filling materials (MTA or CEM cement), each group was then divided into two subgroups. Finally, specimens were cleared for assessing the amount of apical dye (Indian ink) penetration. The data were analyzed using Kruskall-Wallis and Dunn tests.
Results: Laser/CEM cement group showed significantly the lowest mean apical dye penetration. There were no statistically significant differences between Laser/MTA, ultrasonic/MTA and ultrasonic/CEM cement groups.
Conclusion: Based on the findings of this study, CEM cement demonstrated lower rate of apical leakage compared with MTA, when the root-end cavities prepared with Er,Cr:YSGG Laser. The sealing ability of MTA was not different following root-end preparation by ultrasonic or Er,Cr:YSGG Laser.
Mh. Hosseini, A. Kamali, M Mahmoodzadeh Darbandi,
Volume 23, Issue 1 (6-2010)
Abstract
Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movements and to inhibit the pain during tooth movements. Considering the contradictory finding in this respect, the effect of low level laser therapy (LLLT) was evaluated on the pain during orthodontic tooth movement.
Materials and Methods: In this randomized clinical trial study, 12 patients were included with extracted upper first premolars and required canine retraction into extraction site. While in both sides canines were retracted by Niti coil spring, one side was exposed to GaAlAs laser (890nm). LLLT was done on the buccal and palatal mucosa by slow movement of probe. The patients were asked about their pain on both sides 2 days after beginning of retraction. Pain measurement was evaluated with VAS.
Results: Pain perception in LLLT side significantly decreased (P=0.007).
Conclusion: Based on the results, single irradiation of GaAlAs laser (12J energy per tooth) can decrease pain perception.
Mh. Hosseini, M. Mahmoodzadeh Darbandi, A. Kamali,
Volume 24, Issue 3 (6-2011)
Abstract
Background and Aims: Lasers with different characteristics have been used to stimulate orthodontic tooth movement. Considering the contradictory findings in this regard, this study was designed to assess the effect of low level laser therapy (LLLT) on the rate of orthodontic tooth movement.
Materials and Methods: In this randomized clinical trial study, 12 patients (4 boys and 8 girls average age:16.9 ± 3.4) with extracted upper first premolars and required canine retraction into extraction site were included. While in both sides canines were retracted by NiTi coil spring, one side was exposed to GaAlAs laser (890 nm). LLLT was done (on the buccal and palatal mucosa by slow movement of probe) at the beginning of the first month. Impression and cast fabrication performed at the beginning of retraction, one and two months later. The amount of retraction on the cast was measured with the aid of a reference plaque fabricated on the rogae using a digital caliper. Data were analyzed using paired sample T-test and one-sample Kolmogorov-Simirnov test.
Results: There was no significant difference in the amounts of canine movement between laser exposed and control sides (P>0.05).
Conclusion: The energy dose of laser used in this study (72 J per each tooth) was not appropriate for increasing dental movement.
Sakine Nikzad, Abbase Azari, Mohamad Ehsan Khalil, Poya Aslani, Sima Shahabi,
Volume 24, Issue 4 (1-2012)
Abstract
Background and Aims: 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.
Materials and Methods: In this experimental in vitro study, 40 Cercon zirconia ceramic blocks were fabricated. The surface treatment was performed using sandblasting with 50-micrometer Al2O3, CO2 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.
Results: 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 CO2 irradiated, Nd:YAG irradiated, and sandblasted specimens, respectively. Significant differences were noted between CO2 (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 (CO2 irradiated specimens: 75%, Nd:YAG irradiated: 66.7%, and sandblasting: 41.7%).
Conclusion: Under the limitations of the present study, surface treatment of zirconia ceramics using CO2 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.
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.
Neda Moslemi, Mohadeseh Heidari, Reza Fekrazad, Hanieh Nokhbatolfoghahaie, Siamak Yaghobee, Ahmadreza Shamshiri, Mozhgan Paknejad,
Volume 27, Issue 1 (4-2014)
Abstract
Background and Aims : Free gingival graft is one of the most predictable procedures for gingival augmentation, but patient’s discomfort and pain during healing period of palatal donor site is a significant concern. The aim of this study was to evaluate the effect of 660nm low power laser on pain and healing in palatal donor sites.
Materials and Methods: The present split mouth randomized controlled clinical trial was performed in 12 patients at the department of periodontics of Tehran University of Medical Sciences. Patients’ allocation was done by balanced block randomization (laser group and placebo group). In laser test group (wave length: 660 nm, power: 200mW, time of irradiation: 32s) was applied immediately post-surgery and in day 1, 2, 4 and 7 after that. In the control group, laser application was done with off power mode. Evaluation of epithelialization and healing was done with H2O2 and photograph. The number of palliative pills and bleeding was recorded. Wilcoxon test was used to analyze healing during the study. Patient’s pain during study was analyzed using repeated measure ANOVA. Mc Nemar test was used to analyze bleeding. Level of statistical significance was set at 0.05.
Results: Laser group showed better epithelialization (P=0.02) and healing (P=0.01) in day 14 after surgery and showed better epithelialization in day 21(P=0.05). No statistically differences were observed between laser group and control group in terms of bleeding and medication (P=0.51), (P=1).
Conclusion: According to the results of this study, the low power laser can promote palatal wound healing during the second and third week after free gingival graft procedures.
Sara Ghadimi, Mohammad Reza Khami, Samaneh Razeghi,
Volume 28, Issue 1 (5-2015)
Abstract
Background and Aims: Despite significant decline in dental caries in recent decades, the disease remains a
public health problem especially in developing countries. In recent years combined application of laser and
fluoride has been introduced as a new caries-preventive measure. The purpose of the present study was to review
the literature on the preventive effect of combined application of laser and fluoride on the dental caries.
Materials and Methods: PubMed, Google Scholar and EMBASE databases were searched for articles published
from 1990 to November 30, 2013. Various combinations of the following keywords were used: Dental caries,
Laser, Fluoride, Fluoride therapy, Prevention and Enamel. The inclusion criteria included all levels of available
evidence. Articles published only in english language were evaluated, and unpublished data were not sought.
Results: Several studies evaluating the effect of laser alone or combined with topical fluoride to prevent dental
enamel demineralization were found. Studies assessing the combined effect were more frequently done on
permanent teeth and just a few studies were done on primary teeth. In total, most of the studies confirmed that
combined application of laser and topical fluoride has a remarkable effect in prevention of enamel
demineralization compared to application of each of them alone.
Conclusion: Laser irradiation combined with topical fluoride application seems to provide the best prevention
effect on the dental caries initiation and progression in enamel of permanent teeth. However, more experimental
and clinical studies are necessary to be done on the primary teeth in this area.
Farshid Shams, Fahime Sadat Sanaei, Nasim Azizi, Ali Peymani, Zeinab Davoudmanesh,
Volume 28, Issue 3 (10-2015)
Abstract
Background and Aims: According to concerns of technical errors in intraoral radiographs and reports of positive effects of central ray laser pointer on the students, technical errors and shortcomings of earlier research, this study was conducted at Department of Oral and Maxillofacial Radiology of Tehran Azad University to determine the role and use of laser pointer in the technical error made by students.
Materials and Methods: This clinical trials study was carried out at the Department of Radiology, Dental School of Azad Tehran University. A total of eighty students were divided into two groups of forty. In the first group the periapical technique was taught without laser guided indicator, while in the second group laser guided indicator was applied in training the students. All students took X-rays from the phantoms. Laser guided indicator is made of one low power red laser diodes.Totally 560 X-rays were taken and the technical errors and the quality of X-rays were evaluated. Data were analyzed statistically using Mann-Whitney and Chi Square tests (&alpha=0.05).
Results: The X-rays taken by students showed significant differences in cone cutting (P<0.001), and overlapping (P<0.001) between the two study groups. In the subjective review of X-ray quality, the difference was also significant (P=0.03).
Conclusion: The use of laser guided indicator as a training aid seems to be practical for easier learning of central ray adjustment and reduction of technical errors in taking X-rays by dental students.
Abbas Majdabadi, Mona Ahadi, Reza Fekrazad,
Volume 29, Issue 1 (7-2016)
Abstract
Background and Aims: Nowadays lasers are used as alternatives to the tooth preparation because of reducing pain and bloodshed. The aim of this study was to observe the effect of ArF laser on the dental hard tissues.
Materials and Methods: For this research human molar teeth with no caries or dental restoration and enamel cracks were used. Irradiation laser energies were taken 95, 70 and 50 mJ for enamel and 80, 70 and 50 mJ for dentine. Then, for each of energy values pulse numbers (repetition rate) were adjusted at 200, 400, 600, 800, 1000 and 1500. Ablation was carried out without water spray on both enamel and dentine. Finally, the dimensions of ablated areas were measured by using a camera connected to the computer and results were applied in graphs.
Results: For each energy value, the ablation dimension increased by increasing pulse numbers. Ablation depth in dentine was more than that of for enamel. Trends of graphs for dentine and enamel were the same. SEM images of ablations by 95 mJ energy on enamel and 80 mJ energy on dentine showed sharp edges.
Conclusion: Ablation depths increased by increasing pulse numbers, for each energy level. However, this increase was not that as expected, because the lack of water spray while irradiating.
Abbas Majdabadi, Mona Ahadi, Reza Fekr Azad,
Volume 29, Issue 2 (11-2016)
Abstract
Background and Aims: Nowadays lasers are used as alternatives to the tooth preparation because of reducing pain, bloodshed and stress. The aim of this study was to observe the effect of Er,Cr:YSGG laser on the dental hard tissues.
Materials and Methods: For this studty, molar teeth with no caries or dental restoration and enamel cracks were used. The laser power were taken from 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5 up to 6 Watts for enamel and 0.5, 1, 1.5, 2, 2.5, 3, 3.5 and 4 Watts for dentine simultaneously with water spray. The ablation effect was observed on both enamel and dentine. Finally, by use of a CCD camera connected to the computer, the dimensions of ablated areas were measured and results were applied in graphs.
Results: Volume of ablation was increased by increasing laser power. Also, by increasing energy value in each stage, the depth of ablation was increased for enamel and dentine. SEM images of ablations by 3.5 and 4 Watts on enamel and 1 and 1.5 Watts on dentine did not show any sharp edges.
Conclusion: The ablation volumes and depth increased by increasing the energy of laser pulses power. The reason for this trend was due to the water spray while irradiating and good absorption of water by laser beam.
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.
Mohammad Hosain Lotfi Kamran, Mahnaz Hatami, Abbas Fallah Tafti, Mohammad Malekzadeh,
Volume 30, Issue 3 (10-2017)
Abstract
Background and Aims: To create a good adhesion between porcelain veneers and zirconia restorations has been important issues is the prosthesis. The aim of this study was to identify an effective way to prepare the zirconia surface infrastructure to increase its shear bond strength to the porcelain veneer.
Materials and Methods: 75 samples of zirconia (Y-TZP) cylinders (diameter of 7 mm and a thickness of 3 mm) were fabricated. Based on the surface treatment, specimens were randomly divided into 3 groups: control, air abrasion and
Er-YAG laser. After surface treatment, the specimen surfaces were examined by SEM. Using a metal mold, the porcelain was veneered on the zirconia surface and then fired. After thermocycling, the shear bond strength of porcelain to zirconia was measured and then the failure mode of each specimen was analyzed using a stereo-microscope. Data were analyzed by one-way ANOVA and Tukey test.
Results: Significant differences were observed between the mean shear bond strength of different groups (P=0.001). The greatest amount of shear bond strength was observed in the group (S) and the lowest bond strength in the control group. Analysis of failure modes showed no statistically significant difference in the type of failure among study groups. The adhesive failure was predominating failure at the intersection of porcelain veneers.
Conclusion: The highest shear bond strength between zirconia and porcelain was achieved by sandblasting the zirconia surfaces compare with that of Er_YAG application.
Mandana Khatibi, Arash Azizi, Abbas Kamali, Soheila Mohammadian,
Volume 31, Issue 2 (9-2018)
Abstract
Background and Aims:The erosive and ulcerative forms of Oral lichen planus causes pain and irritation, affects the nutrition and biological quality of the patient. Considering the high prevalence of the disease, the complications of conventional treatments and the resistance to classical drug therapy, the aim of this study was to compare the effect of infrared low level laser and triamcinolone acetonide mouth rinse on treatment of oral lichen planus lesions.
Materials and Methods:In this double blind clinical trial, 24 patients were selected randomly according to the inclusion and exclusion criteria and divided into two groups of 12. Before and after the study, pain and burning sensation index (VAS), apparent shape and score of the lesion and size of the lesion were recorded in the patients. We treated the first group with low level infrared laser (810 nm) twice a week with 0.5-2 j/cm2 energy density and 300 mW/cm2 power density up to a maximum of 10 sessions. For the second group, we prescribed a mouth rinse of triamcinolone acetonide 0.2% four times a day with antifungal drugs for a month. Then, the study`s criteria were recorded after the completion of treatment. All data were statistically analyzed using the repeated measure ANOVA test to compare the quantitative changes over time, The Mann-Whitney U test was used to compare the rank variables between two groups at any time and Friedman test for each group between different times.
Results: There was no significant difference between the groups in terms of severity of pain (P=0.255), score and size (P=0.186), and appearance (P=0.178) of the lesions among two groups. Although the two groups showed a significant decrease in all three indicators.
Conclusion:Considering that in both groups, all three indices were improved and these improvements were similar, it seems that laser therapy can be effective. It could be used as a therapeutic alternative in treating patients with OLP (Oral Lichen Planus) especially in cases with contraindication in corticosteroid administration or lack of appropriate therapeutic response or when there is resistance to treatment.
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.
