Effect Of CO2 Laser Irradiation Research Articles

Rehardening of Eroded Enamel with CPP-ACFP Paste and CO2 Laser Treatment.

Background Diet and lifestyle can destroy tooth structure due to the dissolution of enamel by acidic beverages. The present study evaluated the effect of CO2 laser irradiation and CPP-ACFP (casein phosphopeptide and amorphous calcium phosphate with fluoride) paste on the remineralization of enamel eroded by carbonated soft drinks. Methods In the present in vitro study, 46 human sound premolar teeth were sectioned mesiodistally to achieve 84 samples. Fourteen samples were assigned to the positive control group (G1), and the remaining samples were immersed in 500 mL of cola drink for 2 minutes, followed by rinsing with distilled water for 10 seconds. This procedure was carried out three times to create erosive lesions. Then, the 60 eroded samples were randomly assigned to five groups of G2 to G6 in terms of the treatment as follows: negative control (G2), CO2 laser irradiation (G3), CPP-ACFP paste (G4), CO2 laser irradiation followed by CPP-ACFP paste application (G5), and CPP-ACFP paste application followed by CO2 laser irradiation (G6). The mean surface microhardness of the enamel surface was evaluated and determined at three points for each sample. Data were analyzed with one-way ANOVA and Tukey HSD tests (α = 0.05). Results The highest and the lowest hardness values were recorded in the G1 (314 ± 12 kg/mm2) and G2 (213.7 ± 12 kg/mm2) groups, respectively. ANOVA revealed significant differences between the study groups (P < 0.001). Two-by-two comparisons showed significant differences between the G2 group and the other groups, indicating the efficacy of all the treatment modalities in tooth remineralization and rehardening procedures (P < 0.05). Only in group G6, the enamel microhardness was not significantly different from the G1 positive control group (P > 0.05). Conclusion Considering the parameters used in the present study, CO2 laser irradiation or CPP-ACFP paste application alone increased eroded enamel's surface hardness; however, their sequential application was more effective in rehardening the eroded enamel's surface to near-normal levels.

Dependence of morphology evolution of fused silica on irradiation parameters of CO2 laser

The influence of CO2 laser parameters on the irradiation effect of the fused silica was studied. The morphological characteristics of fused silica treated by a CO2 laser with varying power and frequency were studied experimentally. The properties of the irradiated area were studied by acid etching and hydrophilicity methods in order to verify the effect of CO2 laser irradiation on the SiO2 network. The temperature characteristics of the irradiated region were also calculated using numerical simulations based on experimental parameters. It indicated that the frequency of the CO2 laser plays a key role in the morphology of the irradiated region, and more attention should be focused on the size of the affected zone after laser irradiation in order to fully understand the irradiation process. The good agreement found between numerical simulations and experimental results provides a reference for further research on the application of CO2 laser heating of fused silica.

Effect of CO2 laser irradiation on Eudragit® L100-55, L100, and S100 coatings to modify drug release

Effect of CO2 laser irradiation on Eudragit® L100-55, L100, and S100 coatings to modify drug release

Laser Texturing as a Way of Influencing the Micromechanical and Biological Properties of the Poly(L-Lactide) Surface.

Laser-based technologies are extensively used for polymer surface patterning and/or texturing. Different micro- and nanostructures can be obtained thanks to a wide range of laser types and beam parameters. Cell behavior on various types of materials is an extensively investigated phenomenon in biomedical applications. Polymer topography such as height, diameter, and spacing of the patterning will cause different cell responses, which can also vary depending on the utilized cell types. Structurization can highly improve the biological performance of the material without any need for chemical modification. The aim of the study was to evaluate the effect of CO2 laser irradiation of poly(L-lactide) (PLLA) thin films on the surface microhardness, roughness, wettability, and cytocompatibility. The conducted testing showed that CO2 laser texturing of PLLA provides the ability to adjust the structural and physical properties of the PLLA surface to the requirements of the cells despite significant changes in the mechanical properties of the laser-treated surface polymer.

The Effect of CO2 Laser Irradiation Combined with TiF4 and NaF Varnishes on Enamel Hardness: An In Vitro Study.

To assess the effects of experimental titanium tetrafluoride (TiF4) varnish and commercial sodium fluoride (NaF) varnish with CO2 laser on enamel hardness. Ninety human enamel samples were randomly assigned to one of the following groups: 1. control (no treatment) (CO); 2. NaF varnish (2.26%) (NF); 3. TiF4 varnish (2.45%) (TF); 4. CO2 laser (La); 5. NaF varnish (2.26%) with CO2 laser (NFL); 6. TiF4 varnish (2.45%) with CO2 laser (TFL). Enamel surface changes were determined by Vickers microhardness (VH) test with a load of 1000 g and a dwell time of 12 s. Each sample was indented three times. Data were analysed using one-way ANOVA and Tukey's test. The mean surface microhardness was 245.5 VH in the CO group, 280.3 VH in group NF, 338.7 VH group TF, 277.0 VH in group La, 345.3 VH in group NFL, and 368.0 VH in group TFL. Statistical analysis showed that groups TF, NFL, and TFL had statistically significantly higher surface hardness than the control group (p < 0.05). The microhardness of enamel treated with TiF4 varnish with or without laser irradiation was statistically significantly greater than that of the control group. Thus, using TiF4 to increase enamel surface microhardness can be recommended.

Effect of CO2 Laser Irradiation on the Topographic and Optical Properties of CdO Thin Films

In this study, cadmium oxide (CdO) was deposited on glass bases by thermal chemical spraying technique at three concentrations (0.05, 0.1, 0.15) M and then was irradiated by CO2 laser with 10.6 μm wave length and 1W power. The results of the atomic force microscope AFM test showed that the surfaces of these CdO thin films were homogenous and that the laser irradiated effect resulted in decreasing the roughness of the surface as well as the heights of the granular peaks, indicating a greater uniformity and homogeneity of the surfaces. The optical properties were studied to determine laser effect. The results of optical tests of these thin films showed that the photoluminescence spectra and absorption shifted towards longer wavelengths with increased concentration, and the transmittance was high at high wave lengths. There was a decrease of energy gap values at (0.05, 0.15)M concentrations which were (2.1, 2.25)eV receptively, and an increase in the energy gap value at 0.1 M concentration which was 2.55 eV, and other optical properties have been studied in this paper .In general, we observe that the values ​​of the optical constants of the concentrations (0.05, 0.15)M increase after laser irradiation and are lesser after irradiation at concentration 0.1 M.

Effect of CO2 laser (10.6μm) and Remin Pro on microhardness of enamel white spot lesions.

This study investigated the combined effect of CO2 laser irradiation and Remin Pro paste on microhardness of enamel white spot lesions (WSLs). Seventy-eight intact premolars were randomly assigned into six groups and then stored in a demineralizing solution to create WSLs. Afterwards, the teeth in group 6 (negative control) remained untreated, while groups 1 and 4 were exposed to CO2 laser irradiation (20Hz, 1W, 30s) and Remin Pro paste, respectively. In groups 2 and 3, the teeth were exposed to laser either before (group 2) or after (group 3) Remin Pro application. The teeth in groups 1 to 5 were then immersed in artificial saliva for 90days while subjected to fluoride mouthwash and weekly brushing. Finally, the teeth were sectioned, and Vickers microhardness was measured at the enamel surface and at 50, 100, and 150μm from the surface. One sample of each group was also examined with scanning electron microscope (SEM). Data were analyzed by two-way analysis of variance (ANOVA) and Tukey's test. The significance was set at 0.05. Laser irradiation followed by Remin Pro application (group 2) caused a significant increase in total WSLs' microhardness compared with laser alone (group 1) and control groups (P < 0.05). Microhardness at depths of 100 and 150μm was also significantly greater in group 2 compared with those of group 3 and control groups (P < 0.05). Combined application of CO2 laser with Remin Pro paste, when laser is irradiated before the paste, is suggested for re-hardening of WSLs in deep layers of enamel.

Effect of irradiation with CO2 laser on dog periodontal tissues.

The effects of CO2 laser irradiation on the premolar and molar vestibular gingiva of twenty-one mongrel dogs were studied. The relationship between the irradiated energy, damage due to the radiation and the healing process were observed macroscopically and microscopically. Bleeding was not observed during radiation. The ray did not reach the bone, and damages to the soft tissue could heal easily at less than 10 J irradiation. When the irradiation energy was increased higher than 20 J the healing process was significantly delayed, and irreversible damage to the tooth, partial loss of the alveolar crest and sequestra formation were observed in some cases.

The Effects of CO2 Laser Irradiation on Color and Major Chemical Component Changes in Hardwoods

The influence of laser radiation was evaluated relative to the color and major chemical component changes of three hardwood species. The surfaces of maple (Acer pseudoplatanus L.), beech (Fagus sylvatica L.), and lime (i.e. linden, Tilia vulgaris) wood were exposed to radiation from a CO2 laser (wavelength = 10.6 µm, output power = 45 W). It was observed that increased doses of irradiation resulted in a decrease in the lightness (L*), increase in the total color difference, and a drop in the total polysaccharide content. Compared with the non-irradiated specimens, the ΔL* values at the highest irradiation doses were −56 (maple), −46.8 (beech), and −50.5 (lime). The trends observed in the FTIR spectra also showed there was a relationship between the breaking of C=O and C=C bonds in important functional groups in the lignin, hemicellulose, and carbohydrates. A highly linear correlation (R2 from 0.902 to 0.987) was observed between the increase in the ΔL* and decrease in the hemicellulose content, which degrades faster than other basic wood components. Such a phenomenon may have been related to the formation of new chromophore structures, which caused the color changes in the wood.

CO2 laser dentin surface treatment most effectively increased ceramic shear bond strength.

The purpose of this study is to determine the effect of CO2 laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS) of resin cement to CAD/CAM ceramics bonded to dentin. Forty-eight (CAD/CAM) ceramic discs were prepared and grouped by material, i.e. lithium disilicate (Emax CAD) and zirconia ceramic (Emax ZirCAD), distributed into four different groups: group A, lithium disilicate (Li) CO2/HF/Si; group B, Li: HF/Si; group C, zirconia (Zr) CO2/Sb/Si; group D, Zr: Sb/Si. It was shown significant difference between irradiated and non-irradiated groups in terms of shear bond strength for zirconia ceramics (p value = 0.039). CO2 laser irradiation increases shear bond strength for both CAD/CAM ceramics bonded to dentin.

Effects of CO2 laser irradiation on matrix-rich biofilm development formation-an in vitro study.

BackgroundA carbon dioxide (CO2) laser has been used to morphologically and chemically modify the dental enamel surface as well as to make it more resistant to demineralization. Despite a variety of experiments demonstrating the inhibitory effect of a CO2 laser in reduce enamel demineralization, little is known about the effect of surface irradiated on bacterial growth. Thus, this in vitro study was preformed to evaluate the biofilm formation on enamel previously irradiated with a CO2 laser (λ = 10.6 µM).MethodsFor this in vitro study, 96 specimens of bovine enamel were employed, which were divided into two groups (n = 48): 1) Control-non-irradiated surface and 2) Irradiated enamel surface. Biofilms were grown on the enamel specimens by one, three and five days under intermittent cariogenic condition in the irradiated and non-irradiated surface. In each assessment time, the biofilm were evaluated by dry weigh, counting the number of viable colonies and, in fifth day, were evaluated by polysaccharides analysis, quantitative real time Polymerase Chain Reaction (PCR) as well as by contact angle. In addition, the morphology of biofilms was characterized by fluorescence microscopy and field emission scanning electron microscopy (FESEM). Initially, the assumptions of equal variances and normal distribution of errors were conferred and the results are analyzed statistically by t-test and Mann Whitney test.ResultsThe mean of log CFU/mL obtained for the one-day biofilm evaluation showed that there is statistical difference between the experimental groups. When biofilms were exposed to the CO2 laser, CFU/mL and CFU/dry weight in three day was reduced significantly compared with control group. The difference in the genes expression (Glucosyltransferases (gtfB) and Glucan-binding protein (gbpB)) and polysaccharides was not statically significant. Contact angle was increased relative to control when the surface was irradiated with the CO2 laser. Similar morphology was also visible with both treatments; however, the irradiated group revealed evidence of melting and fusion in the specimens.ConclusionIn conclusion, CO2 laser irradiation modifies the energy surface and disrupts the initial biofilm formation.

Impact of combined CO2 laser irradiation and fluoride on enamel and dentin biofilm-induced mineral loss.

The caries-protective effects of CO2 laser irradiation on dental enamel have been demonstrated using chemical demineralization models. We compared the effect of CO2 laser irradiation, sodium fluoride, or both on biofilm-induced mineral loss (∆Z) and Streptococcus mutans adhesion to enamel and dentin in vitro. Ground, polished bovine enamel, and dentin samples were allocated to four groups (n=12/group): no treatment (C); single 22,600-ppm fluoride (F) varnish (5% NaF) application; single CO2 laser treatment (L) with short pulses (5μs/λ=10.6μm); and laser and subsequent fluoride treatment (LF). Samples were sterilized and submitted to an automated mono-species S. mutans biofilm model. Brain heart infusion plus 5% sucrose medium was provided eight times daily, followed by rinses with artificial saliva. After 10days, bacterial numbers in biofilms were enumerated as colony-forming units/ml (CFU/ml) (n=7/group). ∆Z was assessed using transversal microradiography (n=12/group). Univariate ANOVA with post hoc Tukey honestly-significant-difference test was used for statistical analysis. Bacterial numbers were significantly higher on dentin than enamel (p<0.01/ANOVA). On dentin, LF yielded significantly lower CFUs than other groups (p=0.03/Tukey), while no differences between groups were found for enamel. The lowest ∆Z in enamel was observed for L (mean/SD 2036/1353vol%×μm), which was not only significantly lower than C (9642/2452vol%×μm) and F (7713/1489vol%×μm) (p<0.05) but also not significantly different from LF (3135/2628vol%×μm) (p>0.05). In dentin, only LF (163/227) significantly reduced ∆Z (p<0.05). CO2 laser irradiation did not increase adhesion of S. mutans in vitro. Laser treatment alone protected enamel against biofilm-induced demineralization, while a combined laser-fluoride application was required to protect dentin.

CO2 laser and/or fluoride enamel treatment against in situ/ex vivo erosive challenge

ABSTRACTObjective This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF) application, separately and in combination, on enamel resistance to erosion.Material and Methods During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2). APF gel (1.23%F, pH 3.5) was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukey's test (p<0.05).Results CO2 laser alone (2.00±0.39 µm) did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm). Fluoride treated enamel, associated (1.50±0.30 µm) or not (1.47±0.63 µm) with laser irradiation, significantly differed from the control.Conclusion The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear.

Effect of CO2 Laser Irradiation on the Optical Properties of Cadmium Oxide Thin Films Grown by Chemical Spray Pyrolysis (CSP) Method

This paper deals with the effect of CO2 laser irradiation on the optical properties of cadmium oxide (CdO) films prepared by chemical spray pyrolysis (CPS) technique. The films deposited on glass substrate using such as an ideal value concentration of (0.1) M Cd(NO3)2.4H2O at temperature (350°C) ,using 6 spray rate during (10) second for each spray .Transmittance ,absorption, absorption coefficient, optical constants, optical energy gap were recorded in order to estimate these films. The obtained films were exposed to CO2 continuous laser with energy (2) Watt at interval time (15) sec at (1) meter far from the source, extend of wavelength (300- 1100) nm .Results of the (CdO) films reported after irradiation showed on improvement of optical energy gap which is shifted from (2.25) eV to (2.09) eV.

The effect of CO2 laser irradiation plus fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to glass ionomer cement or composite resin restorations

Although the cariostatic effects of CO2 laser on the root surface have been shown, there is scarce information regarding its effects on root secondary caries. The objective of this research was to investigate the effect of the association of CO2 laser and a fluoride dentifrice on the inhibition of secondary caries on root surfaces adjacent to composite-resin or glass-ionomer-cement restorations. Dental blocks of human roots were divided into two groups: composite resin (CR) or glass ionomer cement (GIC). Subsequently, the blocks were divided into four subgroups (n = 10): C, non-fluoride dentifrice; FD, fluoride dentifrice; L, CO2 laser with an energy density of 6.0 J cm−2 + non-fluoride dentifrice; and L + FD, CO2 laser + fluoride dentifrice. The blocks were subjected to pH cycling to simulate a high cariogenic challenge. Dental demineralization around the restorations was quantified by microhardness analysis. The results were subjected to analysis of variance (ANOVA) and the Tukey–Kramer test (p ⩽ 0.05). As for mineral loss, it can be observed that all the groups that were treated with a fluoride dentifrice and laser, used alone or not, were statistically similar and superior to the RC–C group. It was concluded that CO2 laser irradiation and a fluoride dentifrice used alone or combined with each other are efficient surface treatments for preventing secondary root caries, regardless of the restorative material used.

CO&lt;sub&gt;2&lt;/sub&gt;レーザー照射とグラスアイオノマーセメントによる象牙質の再石灰化

We investigated the effects of CO2 laser irradiation combined with immersion in a solution containing fluoride ions on the remineralization of etched dentin surface. Human premolars were divided randomly into four groups (1, control: NL; 2, immersion in fluoride-ion-containing solution: NLF; 3, laser irradiation: L; 4, laser irradiation plus immersion in fluoride-ion-containing solution: LF). Embedded human dentin blocks were etched with phosphoric acid, fixed on a specimen stage, and then a CO2 laser (10.6-µm wavelength) was applied (15 W/cm2), followed by immersion in fluoride-ion-containing solution. Nanoindentation testing was carried out before and after CO2 laser irradiation and during the immersion period, and then the dentin surfaces were observed by scanning electron microscopy. Phosphoric acid etching markedly decreased the mechanical properties (hardness and elastic modulus) of dentin surfaces. The mechanical properties of the etched dentin specimens subjected to laser irradiation plus immersion in fluoride-ion-containing solution recovered significantly during the immersion period compared to those of the other specimens. After immersion for 1 month in the fluoride-ion-containing solutions (NLF, LF), the wide-open dentinal tubules caused by acid etching were partly filled by a remineralized layer. In conclusion, CO2 laser irradiation with low output plus immersion in fluoride-ion-containing solution may enhance the remineralizing ability of etched dentin surface.

Effect of CO2-laser irradiation on properties and performance of thin-film composite polyamide reverse osmosis membrane

CO2-laser irradiation was used to modify the surface properties of thin-film composite (TFC) polyamide reverse osmosis (RO) membranes. These membranes were first synthesized via interfacial polymerization of m-phenylenediamine (MPD) monomers and trimesoyl chloride (TMC) over porous polysulfone ultrafiltration support, followed by a CO2-irradiation. AFM, ATR-FTIR, SEM and contact angle measurements were used to characterize the surface properties of these membranes. The ATR-FTIR results indicated that CO2-laser irradiation did not induce any functional groups on the membrane surface. However, it was found that the laser irradiation enhanced the NaCl salt rejection and slightly reduced the permeate flux. Moreover, the maintenance of the flux in modified membranes was much higher than untreated ones. Specially, after 180 min of filtration, the reduction in initial flux for the unmodified membranes was 22%. However, the reduction in initial flux for the modified membranes was less than 5%. Bovine serum albumin (BSA) filtration revealed an improvement in the antifouling properties of the modified membranes. The changes in the membrane surface morphology showed that the roughness of membrane surface is reduced significantly.

Assessment of the Effect of CO2 Laser Irradiation on the Reduction of Bacteria Seeded on Commercially Available Sandblasted Acid-Etched Titanium Dental Implants: An In Vitro Study.

To evaluate the capability of carbon dioxide (CO₂) laser in reducing Escherichia coli on sandblasted acid-etched (SAE) titanium dental implants. SAE dental implants were contaminated with E coli, incubated in a sterile bacterial culture medium for 24 hours, and then exposed to CO₂ laser (10,600-nm wavelength) in superpulsed waves (SPW) at 1.5, 1.7, and 2 W at 100-Hz frequency and continuous wave (CW) at 1.5, 2, and 2.5 W. The presence of bacteria trapped in the implant surfaces after contamination and decontamination was verified using spectrophotometry. Scanning electron microscopy (SEM) was used to evaluate the topography of laser irradiation. After implant surface contamination was verified, implants were exposed to CO₂ laser irradiation, and bacterial growth was measured with spectrophotometry. The control implants showed the highest bacterial growth (100% growth). Implants exposed to laser showed progressive increase in the percentage of decontamination (DC%) corresponding to the higher wattage in the SPW and CW groups. The DC% were 20.4%, 49.6%, and 51.7% in the SPW group at 100 Hz, at 1.5, 1.7, and 2 W of power, respectively. In the CW group, the DC% were 34.3%, 69.9%, and 85.5% at 1.7, 2, and 2.5 W, respectively. Kruskal-Wallis statistical analysis showed a significant difference between the groups (P < .05). In the pulsed mode (100-Hz) group, statistical analysis showed that the DC% of 1.5 W was significantly lower than the 2 W power. In the CW group, statistical analysis showed that the DC% at 1.7 W was significantly lower (P < .05) than with the other treatments. SEM assessment showed craterlike wear damages and accretions to the implant surfaces that increased progressively as the laser wattage increased. CO₂ laser irradiation failed to completely decontaminate the implant surfaces. SEM analysis demonstrated damage to the top of the dental implant threads at all settings studied. Thus, CO₂ laser irradiation may not be the optimal method to decontaminate implants.

The synergistic effects of CO2 laser treatment with calcium silicate cement of antibacterial, osteogenesis and cementogenesis efficacy

Calcium silicate-based material (CS) has been successfully used in dental clinical applications. Some researches show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm, due to a photo-thermal mechanism. The purpose of this study was to confirm the effects of CO2 laser irradiation on CS, with regard to both material characterization and human periodontal ligament cell (hPDLs) viability. CS was irradiated with a dental CO2 laser using directly mounted fiber optics in wound healing mode with a spot area of 0.25 cm2, and then stored in an incubator at 100% relative humidity and 37 °C for 1 d to set. The hPDLs cultured on CS were analyzed, along with their proliferation and odontogenic differentiation behaviors. The results indicate that the CO2 laser irradiation increased the amount of Ca and Si ions released from the CS, and regulated cell behavior. CO2 laser-irradiated CS promoted cementogenic differentiation of hPDLs, with the increased formation of mineralized nodules on the substrate’s surface. It also up-regulated the protein expression of multiple markers of cementogenic and the expression of cementum attachment protein. The current study provides new and important data about the effects of CO2 laser irradiation on CS. Taking cell functions into account, the Si concentration released from CS with laser irradiated may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.

Antibacterial and Odontogenesis Efficacy of Mineral Trioxide Aggregate Combined with CO2 Laser Treatment

IntroductionMineral trioxide aggregate (MTA) has been successfully used in clinical applications in endodontics. Studies show that the antibacterial effects of CO2 laser irradiation are highly efficient when bacteria are embedded in biofilm because of a photothermal mechanism. The aim of this study was to confirm the effects of CO2 laser irradiation on MTA with regard to both material characterization and cell viability. MethodsMTA was irradiated with a dental CO2 laser using directly mounted fiber optics in the wound healing mode with a spot area of 0.25 cm2 and then stored in an incubator at 100% relative humidity and 37°C for 1 day to set. The human dental pulp cells cultured on MTA were analyzed along with their proliferation and odontogenic differentiation behaviors. ResultsThe results indicate that the setting time of MTA after irradiation by the CO2 laser was significantly reduced to 118 minutes rather than the usual 143 minutes. The maximum diametral tensile strength and x-ray diffraction patterns were similar to those obtained without CO2 laser irradiation. However, the CO2 laser irradiation increased the amount of Ca and Si ions released from the MTA and regulated cell behavior. CO2 laser–irradiated MTA promoted odontogenic differentiation of hDPCs, with the increased formation of mineralized nodules on the substrate's surface. It also up-regulated the protein expression of multiple markers of odontogenic and the expression of dentin sialophosphoprotein protein. ConclusionsThe current study provides new and important data about the effects of CO2 laser irradiation on MTA with regard to the decreased setting time and increased ion release. Taking cell functions into account, the Si concentration released from MTA with laser irradiation may be lower than a critical value, and this information could lead to the development of new regenerative therapies for dentin and periodontal tissue.