Clinical evaluation of Er,Cr:YSGG and GaAlAs laser therapy for treating dentine hypersensitivity: A randomized controlled clinical trial

DNA damage in blood cells exposed to low-level lasers

BACKGROUND AND OBJECTIVE

In regenerative medicine, there are increasing applications of low-level lasers in therapeutic protocols for treatment of diseases in soft and in bone tissues. However, there are doubts about effects on DNA, and an adequate dosimetry could improve the safety of clinical applications of these lasers. This work aimed to evaluate DNA damage in peripheral blood cells of Wistar rats induced by low-level red and infrared lasers at different fluences, powers, and emission modes according to therapeutic protocols.

MATERIAL AND METHODS

Peripheral blood samples were exposed to lasers and DNA damage was accessed by comet assay. In other experiments, DNA damage was accessed in blood cells by modified comet assay using formamidopyrimidine DNA glycosylase (Fpg) and endonuclease III enzymes.

RESULTS

Data show that exposure to low-level red and infrared lasers induce DNA damage depending on fluence, power and emission mode, which are targeted by Fpg and endonuclease III.

CONCLUSION

Oxidative DNA damage should be considered for therapeutic efficacy and patient safety in clinical applications based on low-level red and infrared lasers.

Effects of pulsed Nd:YAG laser on tensile bond strength and caries resistance of human enamel

This study aims to evaluate the effects of pulsed Nd:YAG laser on the tensile bond strength (TBS) of resin to human enamel and caries resistance of human enamel. A total of 201 human premolars were used in this in vitro study. A flat enamel surface greater than 4 × 4 mm in area was prepared on each specimen using a low-speed cutting machine under a water coolant. Twenty-one specimens were divided into seven groups for morphology observations with no treatment, 35% phosphoric acid etching (30 seconds), and laser irradiation (30 seconds) of pulsed Nd:YAG laser with five different laser-parameter combinations. Another 100 specimens were used for TBS testing. They were embedded in self-cured acrylic resin and randomly divided into 10 groups. After enamel surface pretreatments according to the group design, resin was applied. The TBS values were tested using a universal testing machine. The other 80 specimens were randomly divided into eight groups for acid resistance evaluation. Scanning electron microscope (SEM) results showed that the enamel surfaces treated with 1.5 W/20 Hz and 2.0 W/20 Hz showed more etching-like appearance than those with other laser-parameter combinations. The laser-parameter combinations of 1.5 W/15 Hz and 1.5 W/20 Hz were found to be efficient for the TBS test. The mean TBS value of 14.45 ± 1.67 MPa in the laser irradiated group was significantly higher than that in the untreated group (3.48 ± 0.35 MPa) but lower than that in the 35% phosphoric acid group (21.50 ± 3.02 MPa). The highest mean TBS value of 26.64 ± 5.22 MPa was identified in the combination group (laser irradiation and then acid etching). Acid resistance evaluation showed that the pulsed Nd:YAG laser was efficient in preventing enamel demineralization. The SEM results of the fractured enamel surfaces, resin/enamel interfaces, and demineralization depths were consistent with those of the TBS test and the acid resistance evaluation. Pulsed Nd:YAG laser as an enamel surface pretreatment method presents a potential clinical application, especially for the caries-susceptible population or individuals with recently bleached teeth.

Lasers for the Treatment of Dentin Hypersensitivity

This systematic review and meta-analysis assessed the efficacy of lasers in reducing dentin hypersensitivity (DH) as compared with placebo or no treatment. Seven electronic databases and a manual search resulted in 2,538 unique publications. After selection, 13 studies were included in the meta-analysis. A CONSORT-based quality assessment revealed that 3 and 10 studies were at low and high risk of bias, respectively. A random-effects model with the generic inverse variance standardized mean difference (SMD) was used because of expected heterogeneity. Meta-analyses of the baseline-end of follow-up changes in pain revealed no differences for Er,Cr:YSSG vs. placebo (SMD = 2.49; 95% CI, -0.25 to 5.22; p = .07) but did reveal differences in favor of lasers for Er:YAG vs. placebo (SMD, 2.65; 95% CI, 1.25 to 4.05; p = .0002), Nd:YAG vs. placebo (SMD, 3.59; 95% CI, 0.49 to 6.69; p = .02), and GaAlAs vs. placebo (SMD, 3.40; 95% CI, 1.93 to 4.87; p < .00001). High and significant heterogeneity was found for all comparisons. In conclusion, Er:YAG, Nd:YAG, and GaAlAs lasers appear to be efficacious in reducing DH. However, given the high heterogeneity of the included studies, future randomized controlled clinical trials are needed to confirm these results.

Seal that Heals

Introduction

Dentinal hypersensitivity can be treated by dentinal tubule occlusion which prevents any stimuli from causing dentinal fluid movement. This in vitro study aims to compare the dentinal tubule occluding capability of four chemical compounds, a bonding agent, a compound of fluoride and hydroxyapatite, potassium oxalate gel and sodium fluoride varnish.

Materials and methods

Forty dentin samples were divided into four groups of 10 samples each. Group A (treated with Clearfil SE Bond), Group B (treated with Remin Pro), Group C (treated with Potassium Oxalate, Vi-sense,) and Group D (treated with Pro Fluoride varnish). The samples were treated with ethylene diamine tetraacetic acid (EDTA) gel prior to application of desensitizing agents to remove the smear layer and open the dentinal tubule orifice. Following the desensitizing treatment the specimens were washed and dehydrated using graded series of ethanol treatments (25, 50, 75, 90 and 100%). After each treatment tubule occlusion was analyzed by scanning electron microscope.

Results

Qualitative and quantitative analysis demonstrated potassium oxalate gel to cause maximum tubule occlusion followed by Remin Pro > Sodium fluoride varnish > Clearfil SE Bond.

Conclusion

Life expectancy is increasing and patients are retaining their natural teeth for a longer time due to effective treatment strategies. The results showed the potential use of these products as an effective means of tubule occlusion.

How to cite this article

Benjamin S, Roshni, Pradhan S, Nainan MT. Seal that Heals. World J Dent 2012;3(3):243-246.