Effect of different activations of silver nanoparticle irrigants on the elimination of Enterococcus faecalis

Clinical Oral Investigations - This study aimed to compare the efficacy of silver nanoparticles (AgNPs) irrigating solution alone and following activation with photon-induced photoacoustic...     

The effects of diode laser (660 nm) on the rate of tooth movements: an animal study

Lasers in Medical Science - Low-level laser has been indicated to have the capability to facilitate the differentiation of the osteoclastic and osteoblastic cells which are responsible for the bone...     

Effect of eugenol-containing and resin endodontic sealers on retention of prefabricated metal posts cemented with zinc phosphate and resin cements

PurposeThe aim of this study was to compare the effects of two endodontic sealers on the retention of posts cemented with zinc phosphate or resin cement.Materials and methodsCrowns of 72 mandibular premolars were removed at the cementoenamel junction. Root canals were prepared and specimens were randomly divided into two groups of 36. In each group, 12 specimens were obturated with gutta percha only; 12 specimens with gutta percha/ZOE sealer and 12 specimens with gutta percha/AH26. In the first group, 10 mm Post spaces were prepared with Peeso reamers size 4 and, size 5 stainless steel Paraposts were cemented in with zinc phosphate. In the second group, 10 mm Post spaces were prepared with Fiber Lux size 5.5 drills and size 5 Paraposts were cemented with Panavia F_2.0. After mounting in resin blocks, posts were pulled out by universal testing machine at 1 mm/min and results were analyzed by two-way ANOVA and Dunnett test.ResultsMean forces (in Newtons) required to remove posts cemented with zinc phosphate in canals obturated without sealer, with ZOE, and with AH26 sealers were 270 ± 83, 281 ± 128 and 266 ± 67, respectively; and for posts cemented with Panavia F_2.0 were 520 ± 290, 464 ± 212 and 229 ± 108, respectively. Statistical analysis showed that AH26 significantly reduced retention of posts cemented with Panavia F_2.0 (p < 0.05).ConclusionDifferent sealers had no significant effect on retention of posts cemented with zinc phosphate. However posts cemented with Panavia F_2.0 showed reduced retention in canals obturated with AH26.     

Effects of laser-assisted cosmetic smile lift gingivectomy on postoperative bleeding and pain in fixed orthodontic patients: a controlled clinical trial

Background and objective

Diode lasers are becoming popular in gingival treatment following orthodontic treatments. Despite their merit and clinical implications, postoperative pain and bleeding after surgery with diode lasers are not assessed except in few controversial studies.

Method

This controlled clinical trial was conducted on 30 healthy orthodontic patients aged 17–29 years, needing esthetic-only gingivectomy in the anterior maxilla. The patients were randomly divided into two groups of 15 each: experimental (laser-assisted surgery) and control (traditional surgery using scalpels). The bleeding rate following the surgery was assessed using the bleeding criteria established by the World Health Organization. The postsurgical pain level was recorded using visual analog scales immediately after the surgery and in patients who consumed analgesics, also 2 h after the analgesic consumption. The data were analyzed using the independent-samples t, Mann-Whitney U, and chi-square tests (α = 0.05).

Results

The average bleeding rates were 1.15 and 0.36 in the conventional and laser groups, respectively (Mann-Whitney U P < 0.05). Experimental patients had no postsurgical pain (VAS1 and VAS2 = 0). In the control group, the average VAS1 pain was 5.2 out of 10. The difference between VAS1 values in the control/experimental groups was significant (Mann-Whitney U P < 0.001).

Conclusion

940-nm diode laser seems promising in reducing postoperative bleeding and pain of patients needing cosmetic smile lift surgeries.     

Shear bond strength of metal brackets to feldspathic porcelain treated by Nd:YAG laser and hydrofluoric acid

Lasers in Medical Science - Adult orthodontic treatment requires bonding orthodontic attachment to dental restorations. Ceramics are commonly used as esthetic restorative materials for the crowns...     

Influence of different power outputs of intraoral Nd:YAG laser on shear bond strength of a resin cement to nickel–chromium dental alloy

Up to now, there is no any experience about the application of dental lasers to bond resin composites to metal surfaces in dentistry. The aim of this preliminary study was to evaluate if the laser irradiation of ceramic-covered alloy surface would improve the bond strength of resin to metal, and if different parameters of laser output may influence the strength of this bond. Fifty three cylinders (thickness of 5 mm and diameter of 10 mm) were made up of a commercially available nickel–chromium alloy by lost-wax technique. Forty prepared specimens were divided into four groups. Five specimens in each group were covered by slurry of dental opaque porcelain and irradiated by Nd:YAG laser using different output parameters for each group. Other five specimens in each group were treated using the same laser parameters without porcelain covering. Five sandblasted specimen served as control group. Panavia F2.0 was bonded on the metal surfaces using polyethylene tubes. In ceramic-coated specimens, silane was applied to achieve chemical bond between silica particles and resin cement. All specimens were thermocycled and subjected to shear bond strength (SBS) test (50 kgf at 0.5 mm/min). Two specimens of each ceramic-coated laser-treated groups were studied using scanning electron microscopy and wavelength dispersive X-ray spectroscopy which showed stabilization of silica particles on the metal surface. ANOVA procedure showed that although shear bond strength was significantly higher in porcelain-covered laser treated samples, but the effect of power output of laser irradiation was not significant (P?=?0.917). There were no statistically significant difference between SBS in control samples and laser treated specimens without porcelain covering. It can be concluded that Nd:YAG laser surface treatment may improve the silica coating of alloy surface to achieve better resin–metal bond.     

Comparative efficacy of Er,Cr:YSGG and Er:YAG lasers for etching of composite for orthodontic bracket bonding

Several techniques have been proposed to obtain a durable bond, and the efficacy of these techniques is assessed by measuring parameters such as bond strength. Laser has provided a bond strength as high as that of acid etching in vitro and has simpler use with shorter clinical time compared to acid etching. This study aimed to compare the efficacy of Er:YAG and Er,Cr:YSGG lasers for etching and bonding of composite to orthodontic brackets. No previous study has evaluated the effect of these particular types of laser. A total of 70 composite blocks were randomly divided into five groups (n?=?14): group 1, etching with phosphoric acid for 20 s; group 2, Er:YAG laser irradiation with 2 W power for 10 s; group 3, Er:YAG laser with 3 W power for 10 s; group 4, Er,Cr:YSGG laser with 2 W power for 10 s; group 5, Er,Cr:YSGG laser with 3 W power for 10 s. Metal brackets were then bonded to composites, and after 5000 thermal cycles, they were subjected to shear bond strength test in a universal testing machine after 24 h of water storage. One sample of each group was evaluated under a scanning electron microscope (SEM) to assess changes in composite surface after etching. The adhesive remnant index (ARI) was calculated under a stereomicroscope. Data were statistically analyzed. The mean and standard deviation of shear bond strength were 18.65?±?3.36, 19.68?±?5.34, 21.31?±?4.03, 17.38?±?6.94, and 16.45?±?4.26 MPa in groups 1–5, respectively. The ARI scores showed that the bond failure mode in all groups was mainly mixed. The groups were not significantly different in terms of shear bond strength. Er:YAG and Er,Cr:YSGG lasers with the mentioned parameters yield optimal shear bond strength and can be used as an alternative to acid etching for bracket bond to composite.