Morphological Changes of Human Dentin after Erbium- Doped Yttrium Aluminum Garnet (Er:YAG) and Carbon Dioxide (CO2) Laser Irradiation and Acid-etch Technique: An Scanning Electron Microscopic (SEM) Evaluation

INTRODUCTION: 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)METHODS: 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 withwater 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.RESULTS: 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.CONCLUSION: 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.

Scanning Electron Microscope (SEM) Evaluation of Tooth Surface Irradiated by Different Parameters of Erbium: Yttrium Aluminium Garnet (Er:YAG) Laser

INTRODUCTION: The aim of this study was to investigate the Scanning Electron Microscope (SEM) analysis of tooth surface irradiated by different parameters of Er:YAG laser.METHODS: 15 caries-free extracted human third molars were used in this study. The teeth were put into 5 groups for laser irradiation as follows: Group 1 (power: 2.5 W, Energy: 250 mJ); Group 2(power: 3 W, Energy: 300 mJ); Group 3 (power: 3.5 W, Energy: 350 mJ); Group 4 (power: 4 W, Energy: 400 mJ); Group 5 (power: 4.5 W, Energy: 450 mJ). All samples were prepared by repetition rate of 10 Hz. Then,the samples were prepared for SEM examination.RESULTS: The SEM images showed cleaned ablated surface and exposed dentinal tubules, without production of smear layer.CONCLUSION: 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,like turbine and bur

Clinical Approach of High Technology Techniques for Control and Elimination of Endodontic Microbiota

The main goal in endodontic treatment is to eradicate or at least reduce intraradicular microbial population to levels that are more compatible with periapical lesions healing process. Since endodontic infections are polymicrobial in nature, intraradicular survival of endodontic microbiota and their pathogenic properties are influenced by a combination of their virulence factors. The purpose of this article is to review the endodontic microbiota and their respective virulence attributes, as well as perform a literature review of the effects of disinfection procedures in the treatment of endodontic infections to gain best practices. Conventional technique for root canal preparation includes mechanical debridement and application of antimicrobial irrigants. Recently, laser irradiation has been used to enhance the results of root canal treatment through its thermal effect. To reduce thermal side effects, laser activated irrigation (LAI) and photon induced photoacoustic streaming (PIPS) were introduced. Antimicrobial photodynamic therapy (aPDT) by photochemical reaction uses light at a specific wavelength to activate a nontoxic photosensitizer (PS) in the presence of oxygen to produce cytotoxic products. Different PSs are used in dentistry including methylene blue (MB), toluidine blue O (TBO), indocyanine green (ICG) and curcumin. Among different options, ICG could be the best choice due to its peak absorption at wavelength of 808 nm, which coincides with the commercial diode laser devices. Also, this wavelength has more penetration depth compared to other wavelengths used in aPDT

Comparison of Tooth Color Change After Bleaching With Conventional and Different Light-Activated Methods

Introduction: The demand for esthetic dental treatments is increasing in recent years mainly due to improved oral hygiene and better maintenance of oral health and teeth in older individuals. Bleaching of discolored anterior teeth is the most popular among esthetic dental treatments. Even individuals with sound teeth and adequate esthetics seek to have whiter teeth in the anterior region. The aim of this study was to evaluate tooth color changes following conventional in-office bleaching techniques compared to light-activated methods using different light sources.Methods: Seventy sound anterior teeth (devoided of caries and/or fracture), extracted for periodontal and orthodontic reasons were selected and allocated to 7 groups: (A) control, (B) conventional bleaching (C) LED-activated bleaching, (D) KTP laser-activated bleaching, (E) diode laser-activated bleaching, (F) Nd:YAG laser-activated bleaching and (G) CO2 laser-activated bleaching. Colorimetric evaluation was carried out before and after treatment using a spectrophotoradiometer. Data were analyzed by one- and two-way analysis of variance (ANOVA) as well as multiple comparison methods.Results: The results showed that all bleaching procedures were effective in reducing the yellowness index. However, the KTP laser-activated bleaching was significantly more effective than the other techniques in 95% confidence level. It was also seen that CO2 laser activated method has outperformed groups E, F and G and the conventional bleaching without light activation was not effective at all and represented similar results with the control group. Furthermore, the groups E and G had almost the same results in decreasing the yellowness index.Conclusion: The results showed that all bleaching techniques were effective however, the KTP laser-activated bleaching was significantly more efficient, closely followed by the CO2 laser-activated bleaching technique

Leukoplakia Removal by Carbon Dioxide Laser (CO2) Laser

INTRODUCTION: definitive treatment of oral leukoplakia is very important because of its recurrences and malignant transformation depending on the location, clinical feature,degree of dysplasia and etiological factors. there are different kinds of treatment for this lesion, but using high power laser has some advantages like less pain, swelling, prevention of metastasis, edema, less bleeding (dry surgery) and infection.CASE: a 53_year_old man with leukoplakia lesion with moderate dysplasia on the left side of the ventral surface of the tongue was selected for treatment with co2 laser.the average power is set on 6.2 w with frequency of 20 hz. the irradiation mode was non-contact. the entire lesion evaporated by the laser with a 2 mm safety margin.RESULT: in this case, 80% of lesion had disappeared after 5 weeks and the 20% residual was evaporated again with the same parameters than the first time. no significant clinical differences were seen between the normal and laser-treated tissue.CONCLUSION: using laser in the treatment of oral lesions has many advantages like selective removal of the affected tissues and minimal damage to surrounding tissue, leading to excellent wound healing with no or minimal scar and good functional results

Can Antimicrobial Photodynamic Therapy (aPDT) Enhance the Endodontic Treatment?

  In order to achieve a long-lasting effect, one of the main goals in root canal treatment is to eliminate the endodontic bacteria. Conventional chemomechanical debridement is considered as the basic treatment in root canal therapy, but adjunctive techniques such as antimicrobial photodynamic therapy (aPDT) can also be helpful. The aim of this study was to evaluate reports in the scientific literature that used different photosensitizers (PSs) for bacterial reduction. The literature search was conducted using databases including PubMed, Scopus, and Google Scholar with the keywords “photodynamic therapy,” “antimicrobial photodynamic therapy,” or “photoactivated disinfection” and “endodontic,” “Enterococcus faecalis,” or “root canal treatment,” from 2000 to 2015. By evaluating different studies, it was concluded that aPDT should be applied in combination with conventional mechanical debridement and irrigants. However, it is also important to note that the success rate is critically dependent on the type of the PS, output power of the laser used, irradiation time, pre-irradiation time, and type of tips used.  

Effect of Laser Treatment on Surface Morphology of Indirect Composite Resin: Scanning Electron Microscope (SEM) Evaluation

Introduction: The aim of this study was to evaluate and compare the Scanning electron microscope (SEM) of indirect composite conditioned by Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser, Neodymium-Doped Yttrium Aluminium Garnet (Nd:YAG) laserand Carbon Dioxide (CO2) laser.Methods: 18 indirect composite blocks (GC Gradia DA2, Japan) with 15 × 10 × 10 mm dimensions were made. The bonding surface of these blocks were polished, then the samples were divided into six groups as follow: Er:YAG laser with output power of 0.5 W and frequency of 10 Hz, Nd:YAG laser with output power of 0.25, 0.5 W and frequency of 10 Hz, CO2 laser with output power of 0.5 W and frequency of 10 Hz and 5 Hz, and no treatment. Then, the surfaces were evaluated by SEM.Results: Irregularities were observed in Er:YAG laser samples compared to control group that produced suitable retention for adhesion of cements. Nd:YAG and CO2 lasers showed melting areas.Conclusion: Among different lasers, Er:YAG laser can be used as an alternative technique for surface treatment of indirect composites

The Effect of Different Powers of Er:YAGLaser Treatment on Surface Morphology of an Indirect Composite Resin: SEM Evaluation

Introduction: 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).Methods: 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.Results: 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.Conclusion: Er:YAG laser can be used as an alternative technique for surface treatment and roughening  of indirect resin composites

Evaluation of Tooth Surface Irradiated With Erbium: Yttrium Aluminum Garnet and Carbon Dioxide Lasers by Atomic Force Microscopy

Introduction: T Laser irradiation of dentin surface can affect its surface topography and roughness. Atomic force microscopy (AFM) is among the most efficient tools for determination of surface topography of natural biomolecules in nano-scales. Surface roughness affects plaque retention especially in the cervical region. This study aimed to assess and compare the obstruction of dentinal tubules and dentin surface roughness after irradiation of erbium: yttrium aluminum garnet (Er:YAG )and CO2 lasers for treatment of dentin hypersensitivity (DH) .Methods: Five disc-shaped samples measuring 3 mm in thickness were fabricated by horizontal sectioning of the cervical area of five extracted human molars using a low speed saw. Each disc was divided into 3 segments by a bur under water coolant. The three segments of each disc were placed on a glass slide. First segment: No intervention (control group). Second segment: Er:YAG laser irradiation (2940 nm, 50 mJ, 10 Hz and 0.5 W, 30 seconds) along with water coolant. Third segment: CO2 laser irradiation (10600 nm, 80 Hz, 0.3 W, 30 seconds) along with water coolant. After that, the surfaces underwent non-contact AFM. The diameters of dentinal tubules as well as surface roughness were then measured and statistically analyzed using repeated measures ANOVA.Results: The surface roughness parameters (Ra, Rq) showed increased roughness after laser irradiation and this increase in roughness after Er:YAG laser application was significant compared to the control group (P = 0.048). However, CO2 laser caused no significant change in surface roughness. Also, after Er:YAG laser application, fewer open dentinal tubules were observed and the remaining open tubules had a smaller diameter.Conclusion: Based on the results, Er:YAG laser irradiation obstructs the dentinal tubules and increases the dentin surface roughness. This increase in surface roughness can cause microbial plaque retention and increase the risk of caries and periodontal disease. Application of CO2 laser (compared to Er:YAG) lead to slight but clinically significant obstruction of dentinal tubules and surface roughnes

Scanning Electron Microscope (SEM) Evaluation of Composite Surface Irradiated by Different Powers of Er:YAG Laser

Introduction: The aim of this study was to evaluate the composite surface treated by different powers of Erbium-Doped Yttrium Aluminum Garnet (Er:YAG) laser in comparison with bur preparation via scanning electron microscope.Methods: Fourteen composite resin blocks with 15× 10 × 10 mm dimensions were used in this study. The samples were divided to seven groups as follow: Group 1 (power: 1 W, Energy: 50 mJ); Group 2 (power: 2 W, Energy: 100 mJ); Group 3 (power: 3W, Energy: 150 mJ); Group 4 (power: 4 W, Energy: 200 mJ); Group 5 (power: 5W, Energy: 250 mJ); Group 6 (power: 6 W, Energy: 300 mJ); Group 7: Diamond bur. Then, the samples were prepared for SEM examination.Results: The surface treated by Er:YAG laser showed irregular and micro porous surface.Conclusion: It seems that composite surface treatment by Er:YAG laser can be an alternative method for composite repair if suitable parameters are used.