[show abstract][hide abstract] ABSTRACT: It is widely recognized that Nd:YAG can increase enamel resistance to demineralization; however, the safe parameters and conditions
that enable the application of Nd:YAG laser irradiation in vivo are still unknown. The aim of this study was to determine
a dye as a photoabsorber for Nd:YAG laser and to verify in vitro a safe condition of Nd:YAG irradiation for caries prevention.
Fifty-eight human teeth were selected. In a first morphological study, four dyes (waterproof India ink., iron oxide, caries
indicator and coal paste) were tested before Nd:YAG laser irradiation, under two different irradiation conditions: 60 mJ/pulse
and 10 Hz (84.9 J/cm2); 80 mJ/pulse and 10 Hz (113.1 J/cm2). In a second study, the enamel surface and pulp chamber temperatures were evaluated during laser irradiations. All dyes
produced enamel surface melting, with the exception of the caries indicator, and coal paste was the only dye that could be
completely removed. All irradiation conditions produced temperature increases of up to 615.08°C on the enamel surface. Nd:YAG
laser irradiation at 60 mJ/pulse, 10 Hz and 84.9 J/cm2 promoted no harmful temperature increase in the pulp chamber (ANOVA, p < 0.05). Among all dyes tested, the coal paste was an efficient photoabsorber for Nd:YAG irradiation, considered feasible
for clinical practice. Nd:YAG laser at 84.9 J/cm2 can be indicated as a safe parameter for use in caries prevention.
[show abstract][hide abstract] ABSTRACT: This study investigated whether subablative-pulsed CO2 laser (10.6 μm) irradiation, using fluences lower than 1 J/cm2, was capable of reducing enamel acid solubility. Fifty-one samples of bovine dental enamel were divided into three groups:
control group, which was not irradiated (CG); group laser A (LA) irradiated with 0.3 J/cm2; and group laser B (LB) irradiated with 0.7 J/cm2. After irradiation, the samples were subjected to demineralization in an acetate buffer solution and were then analyzed by
SEM. A finite-element model was used to calculate the temperature increase. The calcium and phosphorous content in the demineralization
solution were measured with an ICP-OES. ANOVA and the t-test pairwise comparison (p < 0.016) revealed that LB showed significantly lower mean Ca and P content values in the demineralization solution than other
groups. A reduction in the enamel solubility can be obtained with pulsed CO2 laser irradiation (0.7 J/cm2, 135 mJ/pulse, 74 Hz, 100 μs) without any surface photomodification and a less than 2°C temperature increase at a 3-mm depth
from the surface.
[show abstract][hide abstract] ABSTRACT: The aim of the present study was to evaluate the effect of CO(2) laser irradiation (10.6μm) at 0.3J/cm(2) (0.5μs; 226Hz) on the resistance of softened enamel to toothbrushing abrasion, in vitro.
Sixty human enamel samples were obtained, polished with silicon carbide papers and randomly divided into five groups (n=12), receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C). After surface treatment they were submitted to a 25-day erosive-abrasive cycle in 100ml sprite light (90s) and brushed twice daily with an electric toothbrush. Between the demineralization periods samples were immersed in supersaturated mineral solution. At the end of the experiments enamel surface loss was determined using a contact profilometer and morphological analysis was performed using scanning electron microscopy (SEM). For SEM analysis of demineralization pattern, cross-sectional cuts of cycled samples were prepared. The data were statistically analysed by one-way ANOVA model with subsequent pairwise comparison of treatments.
Abrasive surface loss was significantly lower in all laser groups compared to both control and fluoride groups (p<0.0001 in all cases). Amongst the laser groups no significant difference was observed. Softened enamel layer underneath lesions was less pronounced in laser-irradiated samples.
Irradiation of dental enamel with a CO(2) laser at 0.3J/cm(2) (5μs, 226Hz) either alone or in combination with amine fluoride gel significantly decreases toothbrushing abrasion of softened-enamel, in vitro.
Journal of dentistry 09/2011; 39(9):604-11. · 2.00 Impact Factor
[show abstract][hide abstract] ABSTRACT: The aims of the present study were to investigate whether irradiation with a CO(2) laser could prevent surface softening (i) in sound and (ii) in already softened enamel in vitro.
130 human enamel samples were obtained and polished with silicon carbide papers. They were divided into 10 groups (n = 13) receiving 5 different surface treatments: laser irradiation (L), fluoride (AmF/NaF gel) application (F), laser prior to fluoride (LF), fluoride prior to laser (FL), non-treated control (C); and submitted to 2 different procedures: half of the groups was acid-softened before surface treatment and the other half after. Immersion in 1% citric acid was the acid challenge. Surface microhardness (SMH) was measured at baseline, after softening and after treatment. Additionally, fluoride uptake in the enamel was quantified. The data were statistically analysed by two-way repeated measurements ANOVA and post hoc comparisons at 5% significance level.
When softening was performed either before or after laser treatment, the L group presented at the end of the experiments SMH means that were not significantly different from baseline (p = 0.8432, p = 0.4620). Treatment after softening resulted for all laser groups in statistically significant increase in SMH means as compared to values after softening (p < 0.0001). Enamel fluoride uptake was significantly higher for combined laser-fluoride treatment than in control (p<0.0001).
Irradiation of dental enamel with a CO(2) laser at 0.3J/cm(2) (5 μs, 226 Hz) not only significantly decreased erosive mineral loss (97%) but also rehardened previously softened enamel in vitro.
Journal of dentistry 03/2011; 39(6):414-21. · 2.00 Impact Factor
[show abstract][hide abstract] ABSTRACT: Objective
The purpose of the study was to investigate whether dentine irradiation with a pulsed CO2 laser (10.6μm) emitting pulses of 10ms is capable of reducing dentine calcium and phosphorus losses in an artificial caries model.
Archives of Oral Biology - ARCH ORAL BIOL. 01/2011; 56(6):533-539.
[show abstract][hide abstract] ABSTRACT: The purpose of the study was to investigate whether dentine irradiation with a pulsed CO(2) laser (10.6μm) emitting pulses of 10 ms is capable of reducing dentine calcium and phosphorus losses in an artificial caries model.
The 90 dentine slabs obtained from bovine teeth were randomly divided into six groups (n=15): negative control group (GC); positive control group, treated with fluoride 1.23% (GF); and laser groups irradiated with 8 J/cm(2) (L8); irradiated as in L8+fluoride 1.23% (L8F); irradiated with 11 J/cm(2) (L11); irradiated as in L11+fluoride 1.23% (L11F). After laser irradiation the samples were submitted to a pH-cycling model for 9 days. The calcium and phosphorous contents in the de- and remineralization solutions were measured by means of inductively coupled plasma optical emission spectrometer--ICP-OES. Additionally intrapulpal temperature measurements were performed. The obtained data were analysed by means of ANOVA and Tukey's test (α=0.05).
In the demineralization solutions the groups L11F and GF presented significantly lower means of calcium and phosphorous losses than the control group; and in L11F means were significantly lower than in the fluoride group. Both irradiation parameters tested caused intrapulpal temperature increase below 2°C.
It can be concluded that under the conditions of this study, CO(2) laser irradiation (10.6 μm) with 11 J/cm(2) (540 mJ and 10 Hz) of fluoride treated dentine surfaces decreases the loss of calcium and phosphorous in the demineralization process and does not cause excessive temperature increase inside the pulp chamber.
Archives of oral biology 12/2010; 56(6):533-9. · 1.65 Impact Factor
[show abstract][hide abstract] ABSTRACT: Although CO(2) laser irradiation can decrease enamel demineralisation, it has still not been clarified which laser wavelength and which irradiation conditions represent the optimum parameters for application as preventive treatment. The aim of the present explorative study was to find low-fluence CO(2) laser (lambda = 10.6 microm) parameters resulting in a maximum caries-preventive effect with the least thermal damage. Different laser parameters were systematically evaluated in 3 steps. In the first experiment, 5 fluences of 0.1, 0.3, 0.4, 0.5 and 0.6 J/cm(2), combined with high repetition rates and 10 micros pulse duration, were chosen for the experiments. In a second experiment, the influence of different pulse durations (5, 10, 20, 30 and 50 micros) on the demineralisation of dental enamel was assessed. Finally, 3 different irradiation times (2, 5 and 9 s) were tested in a third experiment. In total, 276 bovine enamel blocks were used for the experiments. An 8-day pH-cycling regime was performed after the laser treatment. Demineralisation was assessed by lesion depth measurements with a polarised light microscope, and morphological changes were assessed with a scanning electron microscope. Irradiation with 0.3 J/cm(2), 5 micros, 226 Hz for 9 s (2,036 overlapping pulses) increased caries resistance by up to 81% compared to the control and was even significantly better than fluoride application (25%, p < 0.0001). Scanning electron microscopy examination did not reveal any obvious damage caused by the laser irradiation.
Caries Research 05/2009; 43(4):261-8. · 2.51 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aim of the present study was to investigate the neuroprotective effect of dental pulp cells (DPCs) in in vitro models of Alzheimer and Parkinson disease. Primary cultures of hippocampal and ventral mesencephalic neurons were treated for 24 h with amyloid beta (Abeta(1-42)) peptide 1-42 and 6-OHDA, respectively. DPCs isolated from adult rat incisors were previously cultured in tissue culture inserts and added to the neuron cultures 2 days prior to neurotoxin treatment. Cell viability was assessed by the MTT assay. The co-culture with DPCs significantly attenuated 6-OHDA and Abeta(1-42)-induced toxicity in primary cultures of mesencephalic and hippocampal neurons, and lead to an increase in neuronal viability in untreated cultures, suggesting a neurotrophic effect in both models. Furthermore, human dental pulp cells expressed a neuronal phenotype and produced the neurotrophic factors NGF, GDNF, BDNF, and BMP2 shown by microarray screening and antibody staining for the representative proteins. DPCs protected primary neurons in in vitro models of Alzheimer's and Parkinson's disease and can be viewed as possible candidates for studies on cell-based therapy.
Journal of Neural Transmission 11/2008; 116(1):71-8. · 3.05 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study evaluated the dentinal and marginal permeability of the cut surface after apicoectomy, treatment and retrocavity preparation with Er:YAG and Nd:YAG lasers. Furthermore, scanning electron microscopy (SEM) analysed the morphological alteration of dentin caused by laser irradiation through an optical fiber.
Numerous studies have shown the beneficial effects of laser treatment upon sealing dental apex, avoiding the changes of organic fluids, microorganisms and their by-products between the root canal system and periapex.
Twenty-four extracted and endodontically treated teeth were divided into three groups: GI, apices were resected with Er:YAG laser (350 mJ; 4 Hz) treatment of cut dentinal surface and retrocavity were lased with this same laser (120 mJ; 4 Hz; bur 2051) using the optical fiber 50/10; GII, apicoectomy was performed similar to GI, however the cut dentinal surface was treated with Nd:YAG laser through optical fiber, as well as the retrocavity preparation (100 mJ; 15 Hz; 1.5 W); and GIII (control group), high speed burs were used.
Analysis of methylene blue dye penetration into dentin demonstrated that the specimens of the groups irradiated with laser showed to have lower infiltration indices than the control group. These results were compatible with structural and morphological injuries, evidenced by SEM.
Under the conditions of the present study, apicoectomy using Er:YAG laser, followed by dentinal surface irradiation and retrocavity preparation with Nd:YAG laser, showed to be an alternative clinical tool able to reduce the dentinal permeability.
Photomedicine and Laser Surgery 01/2005; 22(6):533-6. · 1.63 Impact Factor
[show abstract][hide abstract] ABSTRACT: The purpose of this research was to evaluate Nd:YAG laser influence on microleakage of class V composite restorations.
There are few studies concerning laser with restorative materials, considering microleakage. One more sent.
Thirty six cavities were prepared and divided into three groups (n = 12): group 1, control; group 2, Nd:YAG laser irradiation before adhesive technique; group 3, Nd:YAG laser irradiation after adhesive technique was used as the single bottle. Adhesive system Nd:YAG laser parameters were 320 microm of fiberoptic; energy/pulse of 40 mJ of energy/pulse; repetition rate of 15 Hz; power of 0.6 W; pulsed and non-contact, 1 mm from the surface; 30 seconds in scanning mode; energy density was 49.76 J/cm(2). Cavities were restored with microhybrid composite. After having used a polishing technique, thermocycling and impermeabilization procedures were performed and specimens were submitted to a microleakage test consisting of immersion in aqueous solution of 50% silver nitrate for 8 h, in the total absence of light. After washing and drying procedures, teeth were embedded to facilitate buccal-lingual vertical sectioning. Microleakage was revealed by light.
We accomplished Kruskal-Wallis test at 5% level of confidence and observed no statistically significant difference between the tested groups.
Based on the obtained results, it was possible to conclude that Nd:YAG laser in the parameters used, has no influence on marginal microleakage in composite restorations, independent of the moment the laser was used.
Photomedicine and Laser Surgery 09/2004; 22(4):303-5. · 1.63 Impact Factor
[show abstract][hide abstract] ABSTRACT: Failure of apicectomies is generally attributed to dentine surface permeability as well as to the lack of an adequate marginal sealing of the retrofilling material, which allows the percolation of microorganisms and their products from the root canal system to the periodontal region, thus compromising periapical healing. The purpose of this study was to evaluate dentine and the marginal permeability after apicectomy and surface treatment with 9.6 micro m TEA CO(2) or Er:YAG 2.94 micro m laser irradiation. Sixty-five single rooted human endodontically treated teeth were divided into five experimental groups: group I (control), apicectomy with high speed bur; group II, similar procedure to that of group I, followed by dentinal surface treatment with 9.6 micro m CO(2) laser; group III, similar procedure to group I followed by dentinal surface treatment with Er:YAG laser 2.94 micro m; group IV, apicectomy and surface treatment with CO(2) 9.6 micro m laser; and group V, apicectomy and surface treatment with Er:YAG laser 2.94 micro m. The analysis of methylene blue dye infiltration through the dentinal surface and the retrofilling material demonstrated that the samples from the groups that were irradiated with the lasers showed significantly lower infiltration indexes than the ones from the control group. These results were compatible with the structural morphological changes evidenced through SEM analysis. Samples from groups II and IV (9.6 micro m CO(2)) showed clean smooth surfaces, fusion, and recrystallized dentine distributed homogeneously throughout the irradiated area sealing the dentinal tubules. Samples from groups III and V (Er:YAG 2.94 micro m) also presented clean surfaces, without smear layer, but roughly compatible to the ablationed dentine and without evidence of dentinal tubules. Through the conditions of this study, the Er:YAG 2.94 micro m and the 9.6 micro m CO(2) laser used for root canal resection and dentine surface treatment showed a reduction of permeability to methylene blue dye.
Journal of Clinical Laser Medicine & Surgery 05/2004; 22(2):129-39.
[show abstract][hide abstract] ABSTRACT: In an attempt to increase the successful rate of endodontic surgical procedures this study proposes the use of an association of three lasers in apicectomy: Er:YAG laser, (wavelength 2.94 microm pulse mode), Nd:YAG laser (wavelength 1.064 microm, pulse mode), and Ga-Al-As laser, (wavelength of 790 nm, continuous wave).
Previous studies have shown the low success rate of apicectomy by conventional methods due to the presence of remaining bacteria in the surgical site.
The Er:YAG laser was used to perform osteotomy and root resection without vibration, discomfort, less contamination of the surgical site, and no smear-layer on the dentine surface. The Nd:YAG laser irradiation through a fiber performed sealing of the dentinal tubules and bacterial reduction of the cavity bone. In addition, the improvement of healing and better post-operative achieved with the Ga-Al-As laser encourages the use of those lasers in periapical surgeries.
Three years follow-up examination of the clinical case showed radiographically significant decrease of the radiolucent periapical area and no clinical signs and symptoms.
The outcome of this clinical case indicates that the use of those lasers could be considered an alternative, suitable, and useful method to perform an apicectomy.
Journal of Clinical Laser Medicine & Surgery 09/2001; 19(4):193-8.
[show abstract][hide abstract] ABSTRACT: To evaluate dye penetration of proximal vertical slot resin-based composite (RBC) restorations as a function of cavity size and restorative material employed (RBC, ceramic inserts with low-viscosity resin, and RBC with low-viscosity resin liner). Microleakage was measured using rank scoring and linear measurement of dye penetration and ANOVA and non-parametric tests were used to evaluate the statistical significance of the results.
Ninety erupted crack- and caries-free mandibular third molars, extracted for orthodontic reasons, were used. Proximal vertical slots were prepared on the mesial surfaces of the teeth using diamond instruments at high speed under distilled water coolant. Teeth were placed randomly into nine groups. Three sizes of diamond burs of an ultrasonic cavity preparation system were used under low energy in order to standardize cavity size and shape, each tip size being used in 30 different teeth. The gingival margins were prepared 1 mm above the cemento-enamel junction. Specimens were etched, prepared with bonding agent, restored using three different materials, and immersed in a 50% AgNO3 solution for 8 hrs and sectioned to evaluate the dye penetration.
Statistical analysis revealed no statistically significant differences among the nine groups.
American journal of dentistry 01/2001; 13(6):311-4. · 1.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study evaluated microleakage of composite restorations submitted to marginal treatment with Nd:YAG laser and surface sealant.
Previous studies have demonstrated that Nd:YAG-lased enamel melted and became recrystallized with a morphologic appearance similar to lava, and has been used clinically in the sealing of enamel pits and fissures.
Class V cavities in enamel of human premolars were restored with composite resin (Z100, 3M) and randomly divided in six groups: G1, control; G2, surface sealant marginal treatment; G3 to G6, were treated with pulsed Nd:YAG laser (1.064 microm) marginal treatment, contact fiberoptic (300 microm), air cooling, for 30 seconds, powers of 1.2-2 W, repetition rates of 20-30 Hz, energies of 40-100 mJ. Teeth were impermeabilized, immersed in a rhodamine dye, sectioned, and evaluated under stereomicroscope microscopy with scores.
There were significant differences between marginal treatments; there were no differences between groups 1, 2, and 4, and 3,5, and 6; lower values of microleakage were at groups 3, 5, and 6 (Kruskal-Wallis,p = 0.05).
Nd:YAG laser showed improved marginal sealing and decreased microleakage of composite resins restorations.
Journal of Clinical Laser Medicine & Surgery 05/2000; 18(2):75-9.
[show abstract][hide abstract] ABSTRACT: This in vitro study investigates the bactericidal effect of pulsed Ho:YAG laser irradiation in the depth of contaminated dentin specimens.
Previous studies have shown the effectiveness of laser irradiation in bacterial reduction of infected root canal.
Root dentin of bovine teeth were sliced longitudinally in 180 samples of 100 microm, 300 microm, and 500 microm thickness, sterilized, dried, and inoculated on one side, with 1 microL of Enterococcus faecalis suspension. The opposite side's were irradiated four times for 5 seconds each with Ho:YAG laser irradiation, a wavelength of 2.10 microm, using four different energy settings: 1 W/5 Hz; 1 W/10 Hz; 1.5 W/5 Hz, and 2.0 W/5 Hz through a 320-microm quartz fiber at an angle of approximately 5 degrees. In addition, two control groups were investigated, the first was inoculated and not submitted to any treatment, the second was inoculated and treated with NaOCl and H2O2. The remaining bacteria from each dentin sample in a transport media were removed by vibration, serially diluted, and plated out on culture dishes selective for Enterococcus faecalis.
When compared with the untreated control group or even with the group treated with NaOCl plus H2O2, counting of colonies forming units (CFU) from the laser-treated samples revealed a high significant bacterial elimination with a maximum of 98.46% and a minimum of 83.65%.
Our findings demonstrate a significant decrease of the bacterial population in depth, suggesting that the Ho:YAG laser irradiation could be effective to eliminate the microorganisms harbored within dentin or contaminated canals.
Journal of Clinical Laser Medicine & Surgery 05/2000; 18(2):81-7.
[show abstract][hide abstract] ABSTRACT: In the present study, the authors evaluated tensile bond strength of composite resin to dentin treated with Nd:YAG laser before and after bonding procedures.
Lasers have been widely used in dentistry and have contributed to the development of new technologies. Adhesive systems have been indicated for most dental procedures and have produced good results. Studies concerned with the combined use of this adhesive system was the subject of this study.
Thirty noncarious human anterior teeth, freshly extracted, for periodontal reasons, were used. After grinding the buccal dentinal surface until its exposition, specimens were separated into three groups and received the following treatments: (group 1) control--acid etching plus primer plus bond; (group 2) laser plus acid etching plus primer plus bond; (group 3) acid etching plus primer plus bond plus laser. Specimens of composite resin (Z100, 3M, Saint Paul, MN) were constructed on an inverted truncated 3-mm diameter cone mold. Tensile bond strength was performed using Inströn Universal machine, at 0.5 mm/min speed.
Analysis of variance (ANOVA) (p < 0.05) determined that the type of dentinal treatments used had an influence on tensile bond strength. Tukey's test, however, showed that group 1 (15.46) and 3 (15.67) had similar results both of which were higher than group 2 (4.57).
Based on the results obtained, one can conclude that group 1 (without laser) and group 3 (laser after bonding) had similar results, both higher than those observed for group 2 (laser before bonding). These results indicate that more research is needed about how a hybrid layer is formed when laser radiation is used.
Journal of Clinical Laser Medicine & Surgery 02/1999; 17(4):165-9.
[show abstract][hide abstract] ABSTRACT: The Nd:YAG laser irradiation of dental enamel was evaluated in enamel demineralization experiments in a Streptococcus mutans culture media.
Previous studies had shown that a continuous wave Nd:YAG laser at an energy of approximately 67 mJ may induce an increased acid resistance in human dental enamel when exposed to severe demineralization conditions.
Enamel windows of 3 x 4 cm in the buccal surface were irradiated with a continuous wave Nd:YAG laser at a wavelength of 1,064 microns using energy densities of from 83.75 to 187.50 J/cm2. Enamel windows of 3 x 4 cm on the lingual surface served as control (without the laser irradiation). The enamel windows were then exposed to a Streptococcus mutans culture media at a temperature of 37 degrees C for 15 and 21 days. The laser effects and demineralization were examined both by optical microscopy and scanning electron microscopy (SEM).
A comparison between the lased and the unlased windows of enamel showed fusion and recrystalization of the enamel and increased acid-resistance in all groups irradiated with the Nd:YAG laser. On the other hand, the 3 x 4 delimited enamel surfaces from the control group (not irradiated with the Nd:YAG laser) showed 100% demineralization.
These findings are consistent with the finding that laser irradiation of dental results in significant reduction of the effective solubility of enamel mineral.
Journal of Clinical Laser Medicine & Surgery 02/1999; 17(4):171-7.