جستجوی مقالات مرتبط با کلیدواژه « er:yag lasers » در نشریات گروه « پزشکی »

Polyether ether ketone (PEEK) has low surface energy and high resistance to chemical surface treatments. Therefore, different surface treatments such as laser conditioning should be investigated. There is a gap of information regarding the efficacy of laser irradiation in the surface treatment of PEEK, and the efficacy of several laser types needs to be evaluated for this purpose. This study aimed to assess the effect of surface treatment with erbium-doped yttrium aluminum garnet (Er:YAG) and carbon dioxide (CO2) lasers on shear bond strength (SBS) of PEEK to composite resin veneers.

In this experimental study, 60 rectangular-shaped PEEK samples (7 x 7 x 2 mm) were used. The samples were mounted in auto-polymerizing acrylic resin in such a way that only one surface measuring 7x7 mm remained exposed. The samples were then randomly divided into 3 groups (n = 20) of control, Er:YAG laser surface treatment (Power = 1.5 W, energy density = 119.42 J/cm2, irradiation time = 20 s) and CO2 laser surface treatment (Power = 4 W, energy density = 159.22 J/cm2, irradiation time = 50 s). The bonding agent and PEEK opaque were applied on the surface of samples and they were veneered with a composite resin using a hollow plastic cylinder with an internal diameter of 4 mm. The SBS was then measured and the data were analyzed using one-way ANOVA, Tukey HSD test and Dunnett’s test at 0.05 level of significance.

The SBS of the 3 groups was significantly different (P < 0.001). The Tukey HSD test revealed that the Er:YAG laser had higher SBS than the CO2 laser group (P < 0.001). The Dunnett’s test showed that both Er:YAG and CO2 laser groups yielded higher SBS than the control group (P < 0.001).

The Er:YAG and CO2 laser treatments can increase the SBS of PEEK to composite resin veneers, although the Er:YAG laser seems to be more effective for this purpose.

This study was performed to determine the shear bond strength of rebonded mechanically retentive ceramic brackets after recycling with Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser or sandblasting.
Twenty-eight debonded ceramic brackets plus 14 intact new ceramic brackets were used in this study. Debonded brackets were randomly divided into 2 groups of 14. One group was treated by Er:YAG laser and the other with sandblasting. All the specimens were randomly bonded to 42 intact human upper premolars. The shear bond strength of all specimens was determined with a universal testing machine at a crosshead speed of 0.5 mm/min until bond failure occurred. The recycled bracket base surfaces were observed under a scanning electron microscope (SEM). Analysis of variance (ANOVA) and Tukey tests were used to compare the shear bond strength of the 3 groups. Fisher exact test was used to evaluate the differences in adhesive remnant index (ARI) scores.
The highest bond strength belonged to brackets recycled by Sandblasting (16.83 MPa). There was no significant difference between the shear bond strength of laser and control groups. SEM photographs showed differences in 2 recycling methods. The laser recycled bracket appeared to have as well-cleaned base as the new bracket. Although the sandblasted bracket photographs showed no remnant adhesives, remarkable micro-roughening of the base of the bracket was apparent.
According to the results of this study, both Er:YAG laser and sandblasting were efficient to mechanically recondition retentive ceramic brackets. Also, Er:YAG laser did not change the design of bracket base while removing the remnant adhesives which might encourage its application in clinical practice

Periodontitis is an inflammatory periodontal disease that leads to tooth loss. Recently laser has been introduced as an alternative treatment for periodontitis. The aim of the present study was to compare the effect of Erbium-doped Yttrium Aluminum Garnet (Er:YAG) laser with ultrasonic scaler in patients with moderate chronic periodontitis.
In this randomized single-blind clinical trial, 27 patients with moderate chronic periodontitis were selected. One quadrant of the patients was treated by Er:YAG laser and the other one by ultrasonic scaler. Clinical parameters, including periodontal pocket depth (PPD), papillary bleeding index (PBI) and clinical attachment level (CAL) were measured before, as well as 6 and 12 weeks after treatment. Data were analyzed by SPSS 20 software using Friedman test, paired t test, independent t test and Mann-Whitney test. The significance level was set at 0.05.
The means of clinical parameters in both groups were significantly improved in the first and second follow-ups (P 0.05).
Although both ultrasonic scaler and Er:YAG laser could effectively improve clinical periodontal parameters, the results did not reveal the superiority of Er:YAG laser over ultrasonic scaler or vice versa.

The aim of this study was to evaluate the effect of various concentrations of NaOCl on shear bond strength of composite resin to dentin of primary teeth, prepared with laser and bur.
In this in vitro study, 48 primary molars were sectioned at mesiodistal direction and were randomly divided into 6 groups; G1: bur, G2: bur NaOCl 2.5%, G3: bur NaOCl 5.25%, G4: laser, G5: laser NaOCl 2.5%, G6: laser NaOCl 5.25%. One-Step Plus adhesive was applied after phosphoric acid gel and NaOCl over the dentin surfaces for all groups, and composite resin cylinders were bonded to the samples. After thermocycling, shear bond strengths of composite resin to dentin were measured and statistical analyses were done by means of t test and analysis of variance (ANOVA).
The mean shear bond strength showed no significant difference between the groups prepared with bur (13.82 ± 3.49) and laser (14.18 ± 3.65) (P > 0.05). The mean difference of shear bond strength between three groups G1, G2 and G3 and between G4, G5 and G6 were not statistically significant (P > 0.05). Scanning electron microscopy (SEM) figures showed an irregular surface in laser groups and fairly complete removal of smear layer from the orifices of the dentinal tubules, in the group in which NaOCl was used.
The application of different concentrations of NaOCl does not significantly improve the bond strength in dentin surfaces prepared with laser or bur.

Background. Repairing aged composite resin is a challenging process. Many surface treatment options have been proposed to this end. This study evaluated the effect of different surface treatments on the shear bond strength (SBS) of nanofilled composite resin repairs.
Methods. Seventy-five cylindrical specimens of a Filtek Z350XT composite resin were fabricated and stored in 37°C distilled water for 24 hours. After thermocycling, the specimens were divided into 5 groups according to the following surface treatments: no treatment (group 1); air abrasion with 50-µm aluminum oxide particles (group 2); irradiation with Er:YAG laser beams (group 3); roughening with coarse-grit diamond bur 35% phosphoric acid (group 4); and etching with 9% hydrofluoric acid for 120 s (group 5). Another group of Filtek Z350XT composite resin samples (4×6 mm) was fabricated for the measurement of cohesive strength (group 6). A silane coupling agent and an adhesive system were applied after each surface treatment. The specimens were restored with the same composite resin and thermocycled again. A shearing force was applied to the interface in a universal testing machine. Data were analyzed using one-way ANOVA and post hoc Tukey tests (P Results. One-way ANOVA indicated significant differences between the groups (P Conclusion. All the surface treatments used in this study improved the shear bond strength of nanofilled composite resin used.

The purpose of this study was to evaluate amalgam surfaces treated by different output powers of erbium-doped yttrium aluminum garnet (Er:YAG) laser by scanning electron microscope (SEM). Twenty-one amalgam blocks (8 mm × 8 mm, 3 mm thickness) were prepared by condensing silver amalgam (into putty impression material. After keeping them for 24 hours in distilled water, they were divided into 7 groups as follow: G1: Er:YAG laser (1 W, 50 mJ), G2: Er:YAG laser (2 W, 100 mJ), G3: Er:YAG laser (3 W, 150 mJ), G4: Sandblast, G5: Sandblast + Er:YAG laser (1 W, 50 mJ), G6: Sandblast +Er:YAG laser (2 W, 100 mJ) and G7: Sandblast +Er:YAG laser (3 W, 150 mJ). Then after preparation of all samples, they were examined by SEM. The SEM results of amalgam surfaces treated by different output powers of Er:YAG laser showed some pitting areas with non-homogenous irregularities It seems that the application of sandblasting accompanied by Er:YAG laser irradiation can provide proper surface for bonding of orthodontic brackets.

Pyogenic granuloma (PG) is a common tumor-like growth of the oral cavity, considered to be of non-neoplastic nature, often caused by constant low-grade trauma as well as poor oral hygiene and maybe due to hormonal disturbances. Surgical excision, and removal of underlying cause in some cases, is the preferred method of treatment as it is only a benign lesion.In order to remove this lesion, scalpel, cryosurgery and laser are used. Currently different lasers, with adequate parameters, are used for the surgery of PG, which include CO2 (Carbon Dioxide Laser), Nd:YAG (Neodymium-Doped Yttrium Aluminium Garnet), Diode and Er Family amongst others. In this present case, due to the proximity of the lesion with dental hard tissue, Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) laser appears to be the more appropriate laser.The application of Laser is also a newly recommended technique. The aim of this study is to assess the stages of treatment, recovery and recurrence of PG when the Er:YAG laser is used. Furthermore this study aims to also evaluate the friendliness of this method with regards to the surgeon (therapist).Case report: A 24-year-old female was referred to the Laser Research Center of Dentistry of Tehran University of Medical Sciences with a complaint of gingival overgrowth and bleeding. This lesion was in the buccal and palatal side of the 5 and 6 maxillary teeth.Treatment plan included an excisional biopsy of the lesion using Er:YAG laser (3W, 300mJ, 10Hz, Short pulse, with contact headpiece).The bones were then cleaned of soft tissue before being smoothed using a curette.The excised specimen was preserved and sent for histopathological examination. The patient reported no pain after surgery and did not use any systemic antibiotics.The patient was satisfied after the surgery. Chlorhexidine mouthwash was given to the patient. Pathology results confirmed Pyogenic granuloma.After 2 weeks, complete healing was observed. The 9-month follow-up was also carried out in order to check the process of healing as well as the recurrence. Excisional surgery is the preferred treatment method for PG. The application of laser can be considered as an effective and safe technique for excision of this lesion with minimal invasion and many clinical advantages such as less intra-operative bleeding, hemostasis and reduced pain and times of healing.

In recent years, significant developments have been taking place in caries removal and cavity preparation using laser in dentistry. As laser use is considered for cavity preparation, it is necessary to determine the quality of restoration margins. Glass ionomer cements have great applications for conservative restoration in the pediatric field.The purpose of this in vitro study was to compare resin-modified glass ionomer restorations micro-leakage in cavities prepared by Er:YAG (Erbium-Doped Yttrium Aluminum Garnet) laser irradiation and conventional method in primary teeth. This was an in vitro experimental study. Forty primary canine teeth were divided into 2 groups: group 1 represented cavities prepared by the no. 008 diamond bur, group 2 represented cavities prepared by Er:YAG laser. After cavity preparation, samples were restored by resin-modified glass ionomer. The teeth were thermocycled for 700 cycles, placed in 2% methylene blue for 24h and sectioned in the buccolingual direction. The degree of dye penetration was scored by 3 examiners. Data was analyzed using Mann-Whitney Test. There was no statistical difference in micro-leakage between the two modes of cavity preparation (P=0.862) Since preparing conservative cavities is very important in pediatric dentistry, it is possible to use Er:YAG laser because of its novel and portable technology. However, further investigations of other restorative materials and other laser powers are required.

The aim of this study was to evaluate and compare the in vitro effect of the Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser with different radiation distances and high-speed rotary treatment on the shear bond strength of flowable composite to enamel of human permanent posterior teeth. freshly extracted human molar teeth with no caries or other surface defects were used in this study (n=45). The teeth were randomly divided into 3 groups. Group 1: treated with non-contact Er:YAG Laser and etched with Er:YAG laser, Group 2: treated with contact Er:YAG Laser and etched with Er:YAG laser, Group 3 (control): treated with diamond fissure bur and etched with acid phosphoric 37 %. Then the adhesive was applied on the surafces of the teeth and polymerized using a curing light appliance. Resin cylinders were fabricated from flowable composite. Shear bond strength was tested at a crosshead speed of 0.5 mm/min. The amount of Shear Bond Strength (SBS) in the 3 treatment groups was not the same (P<0.05).The group in which enamel surfaces were treated with diamond fissure bur and etched with acid (conrtol group) had the highest mean shear bond strength (19.92±4.76) and the group in which the enamel surfaces were treated with contact Er:YAG laser and etched with Er:YAG laser had the lowest mean shear bond strength (10.89±2.89). Mann-whitney test with adjusted P-value detected significant difference in shear bond strength between the control group and the other 2 groups (P < 0.05). It was concluded that both contact and non-contact Er:YAG laser treatment reduced shear bond strength of flowable resin composite to enamel in comparison with conventional treatment with high speed rotary. Different Er:YAG laser distance irradiations did not influence the shear bond strength of flowable composite to enamel.

Used in conjunction with or as a replacement for traditional methods, it is expected that specific laser technologies will become an essential component of contemporary dental practice over the next decade. The current review is designed to focus on the acid resistance of laser application and tries to introduce laser settings capable to achieve this feature for clinical application. Application of laser for its acid resistance might be a valuable adjunct to conventional acid etching for susceptible sites in high caries risk patients such as patients with rampant caries, who cannot follow oral hygiene instructions due to their systematic disabilities, or those under orthodontic treatment with plaque retentive attachment on their teeth. The key words “enamel acid resistance” and “laser” were searched in PubMed. In brief, the current paper involves the results on 5 items: A summary on laser application; Suggested mechanisms of acid resistance; Different types of laser beams used in acid resistance; Comparison of application of different laser types; and Conclusion.

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:YAGlaser 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.

The purpose of this study was to evaluate the effect of Er:YAG laser on the shear bond strength of resin modified glass ionomer (RMGI) to enamel. Twenty extracted caries-free human premolars were selected. The teeth were embedded in acrylic resin. The buccal surfaces of each sample were ground to plane enamel with carbonated disc. The teeth were randomly divided in two groups. In the first group, the surfaces were treated by Er:YAG laser (350mJ/10Hz). The second group was prepared by carbide bur. Fuji IX RMGI was adhered to surfaces of the samples in both groups in rod shape. The shear bond strength of samples was measured by a universal testing machine. The results of the two groups were analyzed by T- test. The means and standard deviations of shear bond strength of the laser-treated group and the bur-treated group were 6.75 ± 1.99 and 4.41 ± 1.62 Mpa, respectively. There is significant difference in the shear bond strength of RMGI between the two groups (P-value=0.01). The laser group showed better results. Er:YAG laser can be an alternative technology in restorative dentistry.

The aim of this study was to investigate the morphological changes of human dentin after Erbium-Doped Yttrium Aluminum Garnet (Er:YAG), Carbon Dioxide (CO2) 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, CO2 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 CO2 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 CO2 laser has some thermal side effects which make this device unsuitable for this purpose

The main purpose of the present study was to describe the ultra structural changes which happened after treatment of the root surfaces with ultrasonic and hand devices followed by Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser irradiation. Sixty single-rooted maxillary and mandibular teeth which had been extracted due to periodontal problems were collected. Crown and apical parts of the root were cut off using a diamond bur. The specimens were mounted on an acrylic resin in order to make a plain surface of the root accessible. The samples were assigned as following: group1: samples were root planed using conventional hand curette, group2: were prepared by ultrasonic device, group3: roots after scaling by hand instrumentation were treated by Er:YAG laser with 50 mJ/pulse and frequency of 10 Hz, group4: roots were prepared by ultrasonic scaler and consequently were treated by laser. Furthermore, the teeth were dried, sputter-coated with gold, and monitored with scanning electron microscope (SEM). Photomicrographs from ten samples of root surfaces which were taken at magnifications up to 500X revealed that there were not any severe morphologic changes, such as melting and charring, in any group. However, the samples treated by laser irradiation showed more irregularities and distortions. Er:YAG laser setting at 50mj/pulse, as an adjunctive to traditional scaling and root planning, did not induce severe damages to root surfaces, although root surface irregularities were more pronounced in laser treated groups compare to hand instruments.