The Effect of Er.Cr.YSGG Laser with and without the Addition of CNTs Paste on the Occlusion of Dentinal Tubules to Reduce Hypersensitivity: in Vitro Study

This study evaluated the influence of the dental substrates obtained after the use of different caries removal techniques on bonding of a self-etching system. Forty, extracted, carious, human molars were ground to expose flat surfaces containing caries-infected dentine surrounded by sound dentine. The caries lesions of the specimens were removed or not (control--G1) either by round steel burs and water-cooled, low speed, handpiece (G2), or by irradiation with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser (2W, 20 Hz, 35.38 J/cm(2), fiber G4 handpiece with 0.2826 mm(2), non-contact mode at a 2 mm distance, 70% air/20% water--G3) or using a chemo-mechanical method (Carisolv--G4). Caries-infected, caries-affected and sound dentines were submitted to a bonding system followed by construction of a resin-based composite crown. Hour-glass shaped samples were obtained and submitted to a micro-tensile bond test. The bond strength data were compared by analysis of variance (ANOVA), complemented by Tukey's test (P <or= 0.05). The samples of sound dentine presented higher bond strengths than did samples of caries-affected dentine, except for the groups treated with the Er,Cr:YSGG laser. The highest bond strengths were observed with the sound dentine treated with burs and Carisolv. The bond strengths to caries-affected dentine were similar in all groups. Additionally, bonding to caries-affected dentine of the Er,Cr:YSGG laser and Carisolv groups was similar to bonding to caries-infected dentine. Thus, caries-affected dentine is not an adequate substrate for adhesion. Moreover, amongst the caries removal methods tested, the Er,Cr:YSGG laser irradiation was the poorest in providing a substrate for bonding with the tested self-etching system.

Laser etching has an effect on the mineral content of dentin. The aim of this study was to evaluate the mineral content of dentin prepared at three different power settings with an erbium, chromium:yttrium scandium gallium garnet (Er,Cr:YSGG) laser. The enamel of five, lower, wisdom, molar teeth was removed to expose the dentin surface. Four dentin slabs were obtained, then each tooth was randomly divided into four portions (groups 1 W, 2 W, 3 W and control) so that we could evaluate the effect of laser treatment. The Er,Cr:YSGG laser used for the study had a pulse duration of 140 micros, a pulse repetition rate of 20 Hz and a power output range of 0 W to 6 W. Laser energy was delivered through a fiberoptic system to a sapphire tip terminal 6 mm long and 600 microm in diameter, using a non-contact mode. The levels of five elements: magnesium (Mg), phosphorus (P), calcium (Ca), potassium (K), and sodium (Na), in each slab were measured by inductively coupled plasma-atomic emission spectrometry (ICP-AES). There were significant differences between the groups (1 W, 2 W, 3 W and control) for Ca, Mg, Na, P and Ca/P ratio (P<0.05); however, there were no significant differences for K (P=0.43). Laser treatment at 1 W significantly affected the mean percentage weight of all element groups except K. Scanning electron microscopy (SEM) photographs indicated that the surface irregularities increased with increasing power setting.

Background: Severe discomfort due to exposed dentin that is brought on by thermal, tactile, evaporative, electrical, osmotic, or chemical stimulation is known as dentinal hypersensitivity. It typically includes the teeth’s facial surfaces close to the cervical boundary and, typically, in premolars and canines. It might be caused by either cemental or enamel loss. Objective: To assess how well the Er.Cr.YSGG laser seals dentinal tubules when it’s used on exposed dentine. Material and Methods: Twenty-nine natural posterior teeth were prepared, sectioned, cleaned, and made ready for treatment. Samples were split into groups: Group A, the group under negative control (N = 10), and Group B: Er.Cr.YSGG (Waterlase, I plus, Biolase Technology, Irvine, CA) was administered (N = 10) along with a pilot research group (N = 9). Wavelength of 2780 nm, irradiation mode is free-running pulse, power of 0.25 W, frequency of 20 Hz, pulse width of 60 micro s, time of 2 seconds, Fiber tip size: 600 micro m, non-contact mode, power density of 83.33 W/cm2 with 0% water and 0% air, fiber tip fixed on a distance of 1 mm perpendicular to the dentin surface with a clamp holder. Scanning electron microscopy (SEM) was used to analyze dentin-obstructed surfaces. A qualitative evaluation of the micrographs was conducted to analyze the shift in surface features. Data analysis was performed using (spss) software (version 26, IBM,USA) to investigate the data’s normal distribution. The Kolmogorov-Smirnov and Shapiro-Wilk tests revealed that the data had an abnormal distribution. Mann-Whitney U test was carried out to show a comparison between groups (control, laser group). Results: The data obtained from the laser group showed a large reduction in tubular diameter (0.737 micro m) as compared to the control group (3.095 micro m). The selected parameters (0.25W/2s, 83.33 W/cm2) were best to reduce and plug any exposed dentinal tubules without any indication of fissures or cracks. Conclusion: The study conclusively demonstrates that Er:Cr:YSGG laser irradiation offers a viable solution for dentin hypersensitivity by partially or completely occluding dentin tubules. Future clinical trials are warranted to further explore its efficacy. KEYWORDS Dentinal tubules; Er.Cr.YSGG; Hypersensitivity; Laser; Teeth sensitivity.

In this study, we evaluated the safety and efficacy of a novel 2,790-nm erbium-doped yttrium scandium gallium garnet (Er:YSGG) laser system for the treatment of facial photodamage and perioral wrinkles using a single-treatment, high-fluence, high-density protocol. Eleven female participants with Fitzpatrick skin types II to III and facial wrinkles underwent a single full-face fractional ablative treatment with a 2,790-nm Er:YSGG laser. Follow-up visits were completed at 1, 2, and 6 weeks 3 and 6 months. Quartile improvement scale (0-4) and Fitzpatrick wrinkle scores (1-9) were used for the assessments. Based on blinded photographic assessments, the mean difference in Fitzpatrick wrinkle scores for full face wrinkles was 1.5 ± 1.2 (a reduction from 6.6 to 5.1; paired t-test, p = .003). There was also a statistically significant mean reduction of 1.7 ± 1.3 in perioral wrinkle scores (from 6.7 to 5.0; p = .002). No serious adverse events were reported. A novel, fractionated, ablative 2,790-nm Er:YSGG laser can safely and effectively treat photodamage and perioral wrinkles in a single treatment using a high-fluence, high-density protocol. Cutera provided the equipment used in this study and funding to Dr. Goldberg.

Many surgical procedures in soft tissue are performed using diode lasers. Recently, a novel diode laser operating at 445 nm wavelength was introduced in dentistry. The aim of our study was to evaluate the time of surgery and an increase in temperature of titanium implants during its uncovering using 445 and 980 nm wavelengths. The research included 45 pig mandibles (n = 45). The specimens were randomly divided into 3 groups (n = 15) according to the laser irradiation mode and wavelength; G1 - 445 nm laser, power: 3 W, continuous wave (CW), distance: 2 mm, power density: 7460 W/cm2, fiber: 320 μm, noncontact mode; G2 - 445 nm laser (power: 2 W, CW, power density: 4970 W/cm2, fiber: 320 μm, contact mode; G3 (control) - 980 nm laser, power: 2.5 W, CW, power density: 15920 W/cm2, fiber: 200 μm, contact mode. The temperature was measured with a 2 K-type thermocouples (a P1 at collar and a P2 at mid height of the implant). The mean temperature rises measured by the P1 thermocouple were 16.9°C, 36.1°C and 21.6°C in the G1, G2 and G3 group, respectively. Significant differences in temperature rise were found between the G1 and G2 group (p = 0.0007) and the G2 and G3 group (p = 0.01). The mean temperature rises measured by the P2 thermocouple were 1.8°C, 1.4°C and 5.6°C in the G1, G2 and G3 group, respectively. Significant differences in temperature rise were found between the G1 and the G2 or G3 group (p = 0.0001). The significant differences among the study groups in average time necessary for uncovering the implants amounted to 69.7, 54.4 and 83.6 s, respectively (p < 0.05). The application of the 445 nm diode laser in non-contact mode reduced the temperature rise of the implants. The additional pulse intervals during laser irradiation with wavelength of 445 nm when operating in contact mode are needed.

ObjectiveThis study aimed to evaluate the effects of laser application with different agents on dentin surface roughness, tubule occlusion, and bacterial adhesion in vitro.Materials and methodsA total of 216 dentin blocks from bovine incisors were divided into nine groups. Treatments included 5% sodium fluoride (NaF) varnish, casein phosphopeptide–amorphous calcium phosphate (CPP-ACP), Er, Cr: YSGG laser, and diode laser in various combinations. Surface roughness (SR) was measured using a profilometer. S. mutans and S. mitis suspensions were incubated for 24 h, and bacterial adhesion was quantified (×10⁸ Cfu/ml) and visualized using confocal laser scanning microscopy. Tubule occlusion was assessed via SEM imaging and analyzed with ImageJ software. Statistical analysis was performed using one-way ANOVA and Tukey HSD (p = 0.05).ResultsExcept for the CPP-ACP groups treated with laser, all groups exhibited significantly higher surface roughness (p < 0.05); however, this did not influence bacterial adhesion (p > 0.05). All treatments significantly reduced the number and diameter of open dentinal tubules (p < 0.05). The combination of NaF with Er, Cr: YSGG and diode laser enhanced tubule occlusion, while CPP-ACP with laser had no additional effect.ConclusionsIncreased surface roughness, except in CPP-ACP with laser groups, did not affect bacterial adhesion. All desensitization methods effectively promoted tubule occlusion, with the diode laser demonstrating greater efficacy than the Er, Cr: YSGG laser.Clinical significanceLasers should be used with caution as they may increase the roughness of the dentin surface. The combined application of NaF with lasers may improve its clinical efficacy.

Electrically conductive nanocomposites based on ethylene acrylic elastomer (AEM) and multiwalled carbon nanotube (MWNT) have been successfully prepared. Before mixing the MWNT is dispersed in ethanol in presence of ionic liquids such as 1‐methyl‐3‐octylimidazolium chloride (MOIC) and 1‐allyl‐3‐methyl imidazolium chloride (AMIC). Uniform dispersion of MWNT in the nanocomposites is achieved in presence of ionic liquid, which is confirmed by the high‐resolution transmission electron microscopic (HRTEM) microphotographs. The tensile strength increases up to 6 phr of MWNT loading and above that it decreases. However, the tensile strength increases due to the incorporation of ionic liquid assisted dispersed MWNT. It is observed from the dynamic mechanical analysis (DMA) that the storage modulus (E′) and glass transition temperature (Tg) of AEM matrix increase by incorporation of MWNT. The E′ also increases and the tan δmax marginally decreases due to the incorporation of dispersed MWNT in presence of ionic liquids. The dielectric relaxation characteristic properties of AEM/MWNT nanocomposites such as dielectric permittivity (ε′), AC conductivity (σac), impedance (Z*) have been studied as a function of frequency (101−106 Hz) in presence of ionic liquids. The ε′ and σac increase with increasing the MWNT loading due to the easy orientation of dipoles and formation of interconnected conductive networks in the nanocomposites. The electromagnetic interference shielding effectiveness (EMISE) is studied in the X‐band frequency range of 8 to 12 GHz, which significantly improved with increase in MWNT loading. POLYM. COMPOS., 37:2568–2580, 2016. © 2015 Society of Plastics Engineers

Polymeric nanocomposites based on electroactive conductive polymers with nanoparticle fillers have won considerable attention in recent years due to its highly desirable multifunctional characteristics. In the present study, 4, 4’- diaminodiphenyl sulphone has been polymerized and composites were prepared by adding TiO2 and multiwalled carbon nanotube to the polymer by magnetic stirring. These nanocomposites have been characterized using analytical techniques such as UV-Vis, FT-IR, XRD, FE-SEM, EDS and TGA/ DTA analysis. The incorporation of multiwalled carbon nanotube and titanium dioxide in poly 4, 4’-diaminodiphenyl sulphone has been endorsed by FT-IR analysis. It showed that the peak at 453, 431 cm- 1 confirms the stretching vibration of the Ti-O bond of TiO2 and the absorption peaks at 2925 and 2283 cm-1 are imputed to symmetrical telescopic vibrations of the methylene group (-CH2-) of carbon nanotubes. This confirms the incorporation of TiO2 and multi-walled carbon nanotubes into the polymer matrix in the prepared nanocomposites. The XRD pattern showed formation in the nanoscale range (5.94 nm). SEM analysis showed that the variation in polymer morphology depended mainly on titanium dioxide and multi-walled carbon nanotubes.

Objective: The current study was carried out to evaluate the effects of laser and Systemp.desensitizer therapy. Further, scanning electron microscopy (SEM) was used to determine the effects of individual or combined desensitizers on human dentinal tubules. Background: The most common clinical condition that makes people uncomfortable is dentin hypersensitivity (DH). Both lasers and drugs that reduce sensitivity have been used to treat DH. Materials and methods: A total of 100 dentinal samples were taken from newly extracted third molars (affected) and divided into 10 groups (A to J), that is, control (A); Systemp.desensitizer (B); diode laser (980 nm) (C); Nd:YAG laser (D); Er:YAG laser (E); Er,Cr:YSGG laser (F); Systemp.desensitizer + diode laser (G); Systemp.desensitizer + Nd:YAG laser (H); Systemp.desensitizer + Er:YAG laser (I); and Systemp.desensitizer + Er,Cr:YSGG laser (J). SEM was used to evaluate the dentinal specimens in each group (longitudinal and transverse portions), and then images of each sample were captured (20 images/sample). In addition, the number of open dentinal tubules was counted and then the occlusion depth in dentinal tubules was measured. Mann-Whitney and Kruskal-Wallis tests were employed to analyze the obtained data. Results: All treatment procedures and protocols were effective in blocking dentinal tubules (p < 0.05). Compared with the other groups, dentinal tubules in the laser and laser combination therapy groups were significantly obstructed (p < 0.05). Diode and Nd:YAG lasers with or without Systemp.desensitizer showed significantly more tubule occlusion and greater sealing depth than Er:YAG and Er,Cr:YSGG lasers with or without Systemp.desensitizer (p < 0.05). Conclusions: In summary, lasers alone or in combination can play a significant role in occluding the dentinal tubules. However, combining the diode or Nd:YAG laser with Systemp.desensitizers is a more effective treatment strategy and may have immediate and long-lasting effects.

Electrically conductive polymeric membranes were prepared by incorporation of multi-walled carbon nanotubes (MWNTs) onto microbial cellulose membranes cultured by Acetobacter xylinum. To minimize the damage to the inherent properties of the individual MWNTs induced by the chemical modification, we chose to use a surfactant for the purpose of dispersing MWNTs in water. Sodium dodecylbenzene sulfonate was selected for the process of dispersing MWNTs in water. Using scanning electron microscopy and transmission electron microscopy, the individual MWNTs were found to strongly adhere to the surface and the inside of the cellulose membrane. We also investigated electrical conductivity of the cellulose membranes containing well-dispersed MWNTs.

This study aimed to evaluate the effects of two desensitizers and the Er,Cr:YSGG laser on human dentin tubules, applied alone or in combination. Ninety-six dentin specimens were obtained from extracted third molars and divided into six groups: Group 1: no-treatment (Control); Group 2: nano-hydroxyapatite desensitizer (NhapD); Group 3: NhapD+Er,Cr:YSGG laser (L); Group 4: Er,Cr:YSGG laser (L); Group 5: glutaraldehyde desensitizer (GD); and Group 6: GD+L, respectively. All specimens were evaluated using scanning electron microscopy. The diameter and the number of open dentin tubules, the tubules' occluding ratio, and the mineral coverage area were measured via the Image J software at 2000× magnification. Atomic force microscopy was used to determine the blocking mechanism of desensitizing treatments and the surface morphology of dentin specimens. One-way ANOVA and Tukey tests were used for statistical analysis. The number of open tubules and the mean diameter of tubules for all treatment groups showed statistically significant differences from the control group The NhapD+L group had a significantly lower number of open tubules than the L and GD groups. The NhapD+L and L groups significantly had higher occluding ratios than the other groups. The present study showed that the Er,Cr:YSGG laser alone was effective in terms of tubule occlusion and also contributed to increasing the occluding ratio of nano-hydroxyapatite. It may be recommended to use the Er,Cr:YSGG laser with nano-hydroxyapatite desensitizers to achieve effective tubule occlusion.

In order to investigate whether the incorporation of multi-walled carbon nanotubes (MWCNTs) and rectorite (REC) could improve and extend the properties of nanofibrous mats, poly(lactic acid)/MWCNTs/REC ternary composite nanofibrous mats were fabricated via an electrospinning technique. The composite mats still kept a typical electrospun fiber shape and possessed a three-dimensional structure. X-ray photoelectron spectroscopy verified that the addition of MWCNTs and REC was successful. The surface structure of the mats was also analyzed by Raman spectroscopy. Besides, the poly(lactic acid) (PLA) chains could enlarge the interlayer distance of REC, which was confirmed by small-angle X-ray diffraction. Wide-angle X-ray diffraction showed that a higher content of MWCNTs could improve the crystallization of PLA. Thermal analysis results demonstrated that MWCNTs and REC could increase the thermal stability of the composite mats. The cell experiment results indicated that the incorporation of both MWCNTs and REC had little influence on the cell compatibility of the resultant composite mats.

For the in situ incorporation of multiwalled carbon nanotubes (MWCNTs) into sol–gel silica matrix for electrochemical sensing, a water-soluble carboxymethylchitosan derivative having pendant pyrene moieties (CMCSPy) was prepared and used. It was found that such a modified polysaccharide could act both as the stabilizing agent for preparing colloidally stable dispersion of MWCNTs in an aqueous system and the accelerating agent for inducing rapidly the sol–gel transition of water-soluble siliceous precursor, tetrakis(2-hydroxyethyl)orthosilicates (THEOS). By dissolving directly THEOS in aqueous MWCNT dispersions stabilized by CMCSPy, the gel matrices incorporated with well-dispersed MWCNTs could be obtained in mild conditions. Moreover, the incorporation of MWCNTs could shorten the time interval for the gel formation and enhance the gel strength, as confirmed by rheological analyses. By electrochemical experiments, it was found that the as-prepared gel matrix with MWCNTs could be used to construct the amperometric hydrogen peroxide biosensor with an improved response due to the favorable electrochemical characteristics of the incorporated MWCNTs.

This study investigated the effect of conventional and acidified casein phosphopeptide-amorphous calcium phosphate-containing crèmes (CPP-ACP and ACPP-ACP) on dentin permeability (DP) before and after acid challenge, using a fluid-flow measuring device and scanning electron microscopic (SEM) examination. Fifty dentin discs were prepared from intact human third molars. Each tooth was sectioned 3 mm above and below the cementoenamel junction. The smear layer was removed to expose the dentin and dentinal tubules. For fluid-flow measurement, 20 specimens were used and divided into two groups: (a) CPP-ACP (pH=7) and (b) ACPP-ACP (pH=2). The dentin surfaces were treated with the crème for five minutes daily for two weeks, and then an acid challenge was performed using 6% citric acid. Under simulated pulpal pressure, DP was measured at baseline, five minutes, two weeks, and after acid challenge. The remaining specimens were prepared and examined using SEM to investigate dentinal tubule occlusion. DP was not significantly different between the two CPP-ACP-containing crèmes at any test period (p≥0.05). DP after two weeks or acid challenge was significantly lower than that at five minutes (p<0.05). The results were consistent with the SEM micrographs that presented patent dentinal tubules after a five-minute application and partial blockage of dentinal tubules after the two-week application. The dentinal tubules remained partially occluded after acid challenge. Using conventional and acid-modified CPP-ACP-containing crèmes for two weeks decreased DP and partially occluded the dentinal tubules, which resisted acid challenge.

Fused filament fabrication (FFF) and Fused deposition modeling (FDM) are among the most common methods of additive manufacturing technology for a variety of industries. However, the extrusion-based process of these technologies has qualified the usable materials to thermoplastics with inherently limited mechanical properties. Augmenting the properties of these materials by blending them with other polymers or their reinforcement with various additives are among the solutions to overcome this issue. This study examines the result of the introduction of Polybutylene Terephthalate (PBT) to acrylonitrile butadiene styrene (ABS), as one of the most common thermoplastics used in FDM/FFF processes, and explores the effects of the incorporation of Multi-Walled Carbon Nanotubes (MWCNT) to ABS/PBT blend with different filler fractions (0.1, 0.3, and 0.5 wt.%) on the mechanical properties of the printed specimens. In order to assess the mechanical behavior of the printed parts, standard melt flow index (MFI), tensile, three-point flexural, and notched impact tests have been performed on the produced parts. The morphological analyses through Scanning Electron Microscopy (SEM) micrographs have been conducted to inspect the distribution of impregnated MWCNTs and the fracture behavior of the specimens. The most satisfactory improvement has been observed in printed parts of the ABS/PBT/CNT nanocomposites containing 0.3 wt.% of MWCNTs.