Effect of 2.94 μm Er: YAG laser on the chemical composition of hard tissues

AbstractThe aim was to investigate the effect of the Er-YAG laser radiation on morphology and chemicalcomposition of enamel, dentin, and bone. The specimens of the three groups were irradiated with a very long pulse mode (VLP) of 2.94 mm Er-YAG laser with 100 mJ pulse energy and energy density of 8.42 J/cm2 for 30 s, at a repetition rate of 15 Hz. The organic and inorganic content of the samples were investigated by Fourier Transforms Infrared spectroscopy (FTIR). The morphological characteristics were investigated with scanning electron microscopy (SEM) and elemental analysis (calcium and phosphorus) with energy-dispersive X-ray spectroscopy (EDX). FTIR data were analysed with a One-Way ANCOVA test and EDX data with the independent sample t-test. Following the laser radiation, FTIR showed a significant decrease in the organic content of all tissues. The weight percentage (wt %) calcium content of dentin and bone increased significantly following irradiation with a p-value of .002 for both tissues, but the wt % of phosphorus content was not influenced significantly. The morphological alterations expressed signs of fusion in all the samples

The Effectiveness of Three Different Methods for Sterilization of the Endodontic Files (An in Vitro Study)

Background: Sterilization is the procedure by which all the vegetative or sport state microorganisms’ threats are countered. The main aim of sterilization in the health care field is to eradicate the spread of existing infectious diseases and preventing any new infections.  In dentistry, it primarily relates to reuse of instruments to prevent cross-infection and ensure optimal dental care. The complex miniature architecture of endodontic files makes cleaning and sterilization difficult, and some professionals have suggested single use for these instruments.Aim: The purpose of this study was to compare the effectiveness of different methods of sterilization for endodontic instruments: Autoclaving without a  plastic bag, Autoclaving with a plastic bag, CO2 laser, Diode laser, and Glass- bead sterilization. Material and Methods: The study was performed on 60 endodontic K-files, 21 mm long and size 5o, divided into 6 groups, 10 for each, the first group were considered as control. The files contaminated with a homogenous spore suspension of Bacillus thuringiensis. Then, the contaminated files of the 6 groups sterilized by different sterilization methods: Autoclave, Autoclave with a plastic bag, glass-bead, Diode laser, and CO2 laser. The sterilized files washed in 5ml of normal saline and then 0.1ml suspended solution powered in 8cm Petridis of nutrient agar and number of well isolated colonies were counted after 24 hours of incubation at 37 ºC. Results: The study showed that the files sterilized by autoclave were 99.66 % sterile, while with a plastic bag give a 99.32 %sterile. Those sterilized by glass-bead were96.74 % sterile and those with CO2 laser were 93.85 %, and diode lasers were 84.24 % sterile. Statistical analysis of all sterilized groups showed a statistical significant difference between groups regarding their sterilization efficiency. Comparison of the sterilized groups with the control group about their efficacies in sterilization showed that the difference was statistically significant. Conclusion: Autoclave, with or without bag, is considered the best sterilizing technique. To achieve one hundred percent of sterilization the time of autoclave must be suitable to allow the killing of all microorganisms. For faster sterilization other methods could be used but with less effectiveness. Aim: The aim of this study was to investigate the efficacy of three methods for sterilization of endodontic instruments: Autoclaving (with plastic bags and without), laser sterilization (CO2and diode laser) and glass-bead sterilization

Antimicrobial effect of Red Roselle (Hibiscus Sabdariffa) against different types of oral bacteria

This study aimed to compare the antimicrobial effect of an aqueous extract Red Roselle calyx (RE), Chlorhexidine (CH), Amoxicillin-clavulanic acid (ACA), Tetracycline (Tet), and Metronidazole (Met)on Streptococcus mutans (S. mutans), Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) bacteria. The bacterial inhibition zones (BIZ)of the RE (25, 50, 75, 100) mg/ml and CH solutions (0.2%, 2%) were determined using the agar well diffusion method. Additionally, the susceptibility of the tested bacteria against (30 µg) of standard antibiotics of ACA, Tet, and Met was examined. The bacterial minimum inhibitory concentration (MIC) was measured using the Broth Micro dilution method (BMDM). All tests were carried out in triplicates, and water was considered the negative control. For S. mutans, the RE at 50 mg/ml or above concentrations displayed higher BIZ than 0.2% CH. 100 mg/ml of RE recorded a greater BIZ than the 2% CH. The greater BIZ against S. mutans was recorded by Tet. A comparable effect was found with 0.2% CH (75, 100) mg/ml of the RE against S. aureus. Greater BIZ for S. aureus and E. faecalis were reported for 100 mg/ml RE compared to the Tet and Met RE at 100 mg/ml inhibited the E. faecalis growth in a zone size comparable to the CH (0.2%, 2%).The RE with 50,100 mg/ml concentrations showed comparable antimicrobial effect to 0.2%, 2% concentrations of CH, respectively. As an herbal substitute for commercial disinfectants, the RE can be considered an effective final endodontic irrigant and dental mouthwash

Effect of the Er: YAG laser on the shear bond strength of conventional glass ionomer and Biodentine™ to dentine

Objectives: The purpose of this study was to determine if Er: YAG laser etching improves the shear bond strength (SBS) of Biodentin™ and GC Fuji IX ® to dentine. Materials and Methods: Forty human dentine specimens were standardized and embedded in stone. The specimens were randomized into four groups (n = 10). Twenty samples were treated with the Er: YAG laser radiation and 10 of these restored with GC Fuji IX ® and 10 with Biodentine™. The remaining 20 specimens acted as controls (no laser treatment); 10 were restored with GC Fuji IX ® and 10 with Biodentin™. All samples were then stored in an incubator at 37.5°C and 100% humidity for 7 days. The SBS was determined using a Zwick universal testing machine. A two-way analysis of variance test was used to evaluate the statistical difference in SBS between the groups. An independent sample t-test was used to determine the statistical significance of differences between control and lased groups within the same material. Results: A highly statistically significant difference in SBS was found with the laser treatment (P = 0.0001) and material (i.e., Biodentin™ or Fuji IX ® (P = 0.0001). The GC Fuji IX ® group recorded the highest mean SBS required to dislodge the material from the laser-treated dentine surface (1.77 ± 0.22 Mega-Pascal [MPa]). The mean SBS of Biodentin™ to dentine following the laser radiation (1.12 ± 0.16 MPa) was significantly greater compared to the nonlased dentine (0.53 ± 0.09). Pearson Chi-square test indicated a nonsignificant relation between shear strength and mode of failure (P = 0.467). Conclusion: Laser etching of the dentine surfaces yielded a significant increase in the bond strength for both GC Fuji IX ® and Biodentin™. The SBS of Biodentin™ to dentine is greater than with conventional glass ionomer (Fuji IX ®). </p

Micron-scale crack propagation in laser irradiated enamel and dentine studied with nano-CT

ObjectivesThe aim of this study was to see the effect of Er:YAG laser irradiation in dentine and compare this with its effect in enamel. The mechanism of crack propagation in dentine was emphasised and its clinical implications were discussed.Materials and methodsCoronal sections of sound enamel and dentine were machined to 50-μm thickness using a FEI-Helios Plasma (FIB). The specimen was irradiated for 30 s with 2.94-μm Er:YAG laser radiation in a moist environment, using a sapphire dental probe tip, with the tip positioned 2 mm away from the sample surface. One of the sections was analysed as a control and not irradiated. Samples were analysed using the Zeiss Xradia 810 Ultra, which allows high spatial resolution, nanoscale 3D imaging using X-ray computed tomography (CT).ResultsDentine: In the peritubular dentine, micro-cracks ran parallel to the tubules whereas in the inter-tubular region, the cracks ran orthogonal to the dentinal tubules. These cracks extended to a mean depth of approximately 10 μm below the surface. On the dentine surface, there was preferential ablation of the less mineralised intertubular dentine, and this resulted in an irregular topography associated with tubules.Enamel: The irradiated enamel surface showed a characteristic ‘rough’ morphology suggesting some preferential ablation along certain microstructure directions. There appears to be very little subsurface damage, with the prismatic structure remaining intact.ConclusionsA possible mechanism is that laser radiation is transmitted down the dentinal tubules causing micro-cracks to form in the dentinal tubule walls that tend to be limited to this region.Clinical relevanceCrack might be a source of fracture as it represents a weak point and subsequently might lead to a failure in restorative dentistry

Usage of Synthetic Nanoparticles in Masking of White Spot Dental Lesion

Aim: This research aimed to estimate the potential impact of CaO nanoparticles at different concentrations on theremineralization of enamel undergoing cariogenic attack.Materials and methods: Eighteen enamel samples were prepared from sound molars to measure its calcium (Ca) andphosphorus (P) contents by scanning electron microscope equipped with energy dispersive X-ray spectroscopy (SEM-EDS)before and after exposure to cariogenic attack and treatment with saturated gum of 100% CaO nanoparticles (Group 1),50% CaO nanoparticles (Group 2), and ƒ‹ϔ‹…‹ƒŽ saliva (Group 3). The research data were statistically analysed using theone-way ANOVA and Bonferroni tests.Results and discussion: Group 1 of treatment with 100% CaO nanoparticles demonstrated the largest content of Ca (77.8 wt% ± 9.6) followed by Group 2 and 3 (66.6 wt% ± 1.5, 64.4 wt% ± 1.9, respectively). Conversely, Group 1 had the lowestamount of P (18.9 wt% ± 3.9) followed by Group 3 and 2 (29.9 wt% ± 1.4, 31.0 wt% ± 1.1, respectively). Thedemineralization is a reversible process which starts with Ca loss before P loss, so it is logical to use a recalcifying agent (Cacontaining agent) to enhance the ‡…ƒŽ…‹ϔ‹…ƒ‹on and regrowth of hydroxyapatite (HA) crystals where the P could be drivenfrom the saliva. CaO is rich with bioavailable Ca contents, favouring the remineralization of caries lesions. Furthermore, asthe CaO applied in a nano-size particle, it has the ability to diffuse actively through the tiny spaces of the etched enamel.Conclusion: The use of saturated gum with CaO nanoparticles could overcome the cariogenic challenge. The Ca uptakeincreased with the increased concentration of applied CaO nanoparticles

The Effect of Biodentine Maturation Time on Resin Bond Strength When Aged in Artificial Saliva

Biodentine is a calcium silicate cement (CSC) that has been broadly applied in vital pulp therapy. The quality of the Biodentine-composite bond has a significant effect on the longevity of the definitive restoration. The aim of this study is to investigate the shear bond strength (SBS) between Biodentine and composite restoration at different maturation times of Biodentine aged in artificial saliva. Fifteen Biodentine discs were allocated into three groups (n = 5) based on the timeframe of performance of composite restoration: immediate (after 12  min), after 14 days, and after 28 days of Biodentine maturation. Total etch and rinse adhesive system and bulk-fill regular resin composite were used. The shear bond strength and the failure pattern were assessed. One-way ANOVA with the Bonferroni post hoc test was applied for statistical analysis at p &lt; 0.05 . The highest (32.47 ± 8.18 MPa) and the lowest (4.08 ± 0.81 MPa) SBS values were recorded for 14 days and 12 min groups, respectively. Significant statistical differences were reported among the groups, and a high statistically significant difference was found between the immediate group and the other groups. Adhesive failure patterns were evident in all groups. More clinically acceptable bond strength between the Biodentine and overlaid composite restoration is at 14 days after Biodentine maturation. Delaying the coverage of Biodentine later than 14 days may significantly reduce the SBS. Using the artificial saliva as an aging medium may affect the SBS between Biodentine and composite material.</jats:p

The Effect of Biodentine Maturation Time on Resin Bond Strength When Aged in Artificial Saliva

Biodentine is a calcium silicate cement (CSC) that has been broadly applied in vital pulp therapy. The quality of the Biodentine-composite bond has a significant effect on the longevity of the definitive restoration. The aim of this study is to investigate the shear bond strength (SBS) between Biodentine and composite restoration at different maturation times of Biodentine aged in artificial saliva. Fifteen Biodentine discs were allocated into three groups (n = 5) based on the timeframe of performance of composite restoration: immediate (after 12  min), after 14 days, and after 28 days of Biodentine maturation. Total etch and rinse adhesive system and bulk-fill regular resin composite were used. The shear bond strength and the failure pattern were assessed. One-way ANOVA with the Bonferroni post hoc test was applied for statistical analysis at p<0.05. The highest (32.47 ± 8.18 MPa) and the lowest (4.08 ± 0.81 MPa) SBS values were recorded for 14 days and 12 min groups, respectively. Significant statistical differences were reported among the groups, and a high statistically significant difference was found between the immediate group and the other groups. Adhesive failure patterns were evident in all groups. More clinically acceptable bond strength between the Biodentine and overlaid composite restoration is at 14 days after Biodentine maturation. Delaying the coverage of Biodentine later than 14 days may significantly reduce the SBS. Using the artificial saliva as an aging medium may affect the SBS between Biodentine and composite material

The Effectiveness of Three Different Methods for Sterilization of the Endodontic Files (An in Vitro Study)

Background: Sterilization is the procedure by which all the vegetative or sport state microorganisms’ threats are countered. The main aim of sterilization in the health care field is to eradicate the spread of existing infectious diseases and preventing any new infections. In dentistry, it primarily relates to reuse of instruments to prevent cross-infection and ensure optimal dental care. The complex miniature architecture of endodontic files makes cleaning and sterilization difficult, and some professionals have suggested single use for these instruments.Aim: The purpose of this study was to compare the effectiveness of different methods of sterilization for endodontic instruments: Autoclaving without a plastic bag, Autoclaving with a plastic bag, CO2 laser, Diode laser, and Glass- bead sterilization. Material and Methods: The study was performed on 60 endodontic K-files, 21 mm long and size 5o, divided into 6 groups, 10 for each, the first group were considered as control. The files contaminated with a homogenous spore suspension of Bacillus thuringiensis. Then, the contaminated files of the 6 groups sterilized by different sterilization methods: Autoclave, Autoclave with a plastic bag, glass-bead, Diode laser, and CO2 laser. The sterilized files washed in 5ml of normal saline and then 0.1ml suspended solution powered in 8cm Petridis of nutrient agar and number of well isolated colonies were counted after 24 hours of incubation at 37 ºC. Results: The study showed that the files sterilized by autoclave were 99.66 % sterile, while with a plastic bag give a 99.32 %sterile. Those sterilized by glass-bead were96.74 % sterile and those with CO2 laser were 93.85 %, and diode lasers were 84.24 % sterile. Statistical analysis of all sterilized groups showed a statistical significant difference between groups regarding their sterilization efficiency. Comparison of the sterilized groups with the control group about their efficacies in sterilization showed that the difference was statistically significant. Conclusion: Autoclave, with or without bag, is considered the best sterilizing technique. To achieve one hundred percent of sterilization the time of autoclave must be suitable to allow the killing of all microorganisms. For faster sterilization other methods could be used but with less effectivenes