Immersion In Saliva Research Articles

Physio-Mechanic and Microscopic Analyses of Bioactive Glass-Based Resin Infiltrants.

This study aimed to investigate the efficacy and durability of bioactive glass-based dental resin infiltrants. Resin infiltrants were formulated by combining photoinitiated dimethacrylate monomers with three variations of bioactive glass: 45S5 Bioglass (RIS), boron-substituted (RIB), fluoride-substituted (RIF), and pure resins (PR), whereby TOOTH group (TH) and ICON (CN) served as commercial control groups. Teeth samples were prepared, and experimental and control infiltrants were applied on demineralized human-extracted teeth. All the samples were subjected to immersion in artificial saliva and pH cycling for 30 days. The samples from another group underwent tooth brushing simulation for 9600 cycles. Following artificial saliva immersion, the samples' hardness values showed that RIB had the highest values (318.44 ± 3.83) while PR (212.52 ± 9.02) had the lowest values. After immersing into the pH cycling solution, the RIF showed the highest hardness (286.86 ± 5.11), while the lowest values for the CN (143.76 ± 3.50). After the tooth brushing simulation, the teeth samples with RIB showed maximum microhardness values (312.06 ± 16.30) and the weakest for the TH (189.60 ± 6.43). The commercial and experimental enamel resin infiltrants showed almost similar results overall, with RIB demonstrating better microhardness and comparable surface roughness. In contrast, RIF proved more resistant to pH cycling, exhibited higher microhardness, and performed better in surface roughness analysis. These findings suggest that resin infiltrant materials, especially RIF, have promising potential for effectively and esthetically managing white spot lesions.

Exploration of Metal Ion Release from Nickel-Chromium Denture Material: The Role of Saliva pH and Immersion Duration

Nickel chromium (NiCr) is a fixed denture material. Nickel has good physical, and mechanical properties, cheap, but it has low corrosion resistance. One way to increase corrosion resistance is to modify the metal surface by silver plating using the electroplating method. This study examines the effect of saliva pH and immersion time of NiCr metal with silver plating on the release of nickel, chromium, and silver ions. Laboratory experimental studies were 27 samples of NiCr with silver plating (Ø= 10 x 10 x 2 mm) immersed in saliva and divided into 9 groups (n=3): group I (pH 5 for 5 days), group II (pH 7 for 5 days), group III (pH 9 for 5 days), group IV (pH 5 for 10 days), group V (pH 7 for 10 days), group VI (pH 9 for 10 days), group VII (pH 5 for 15 days), group VIII (pH 7 for 15 days), group IX (pH 9 for 15 days). Nickel, chromium, and silver ions release was measured using atomic absorption spectrophotometry. The data obtained were analyzed using two-way ANOVA and post hoc LSD with a 95% confidence level (α =0.05). The results showed a significant difference between salivary pH and immersion time on the ion release (p<0.05). The release of nickel and silver ions increases at acidic pH, while the release of chromium ions increases at alkaline pH. Prolonged immersion (for 15 days) in saliva increases the release of nickel and chromium ions but decreases the release of silver ions.

Surface roughness of supra-nano spherical filled and nanohybrid composite resin after Coffea arabica immersion: an experimental study

ABSTRACTIntroduction: Supra-nano spherical filled composite resin (Omnichroma, Tokuyama, Japan) with sol-gel method has 0.26 μm filler size, while nanohybrid composite resin (ENA HRi, Micerium, Italy) has 0.2-1 μm filler size. Nanofillers enhance resistance from chlorogenic acid contained in Coffea arabica. This study analyzed the surface roughness difference between supra-nano spherical-filled and nanohybrid composite resins after Coffea arabica immersion for 7 and 14 days, with 15 minutes of immersion each day. Methods: This study was an in vitro laboratory experiment with a pretest-posttest control group design. Twenty composite resin samples were immersed in artificial saliva and divided into four groups; supra-nano coffee, nanohybrid coffee, supra-nano saliva (control), and nanohybrid saliva (control). After 24 hours, immersion in Coffea arabica was started for supra-nano coffee group and nanohybrid coffee group for 15 minutes daily until days 7 and 14. Control groups were immersed in saliva. Results: One-way ANOVA showed significant differences in the surface roughness between composite resin groups. Post-hoc Tukey showed a significant difference between supra-nano coffee (0.91± 0.29 μm) and nanohybrid saliva (1.43±0.42 μm). The GLM Repeated Measure test showed significant surface roughness changes in supra-nano after 14 days of immersion in Coffea arabica (1.47±0.13 μm), while nanohybrid experienced surface roughness changes in 7 days of immersion in Coffea arabica (1.94±0.55 μm) and increased in 14 days (2.25±0.47 μm). In saliva immersion (control group), nanohybrid experienced an increase in surface roughness after 14 days, while supra-nano did not experience a significant increase in surface roughness. Conclusion: Supra-nano spherical filled composite resin exhibits greater resistance to changes in surface roughness following immersion in Coffea arabica.KEYWORDSCoffea arabica, nanohybrid, composite resin, supra-nano spherical filled, surface roughness

A Comparative In Vitro Physicochemical Analysis of Resin Infiltrants Doped With Bioactive Glasses.

Objective This study aimed to investigate the longevity and effectiveness of bioactive glass (BAG)-based dental resin infiltrants. Materials and methods The three types of BAG - 45S5 bioglass (RIS), boron-substituted (RIB), and fluoride-substituted (RIF) - were incorporated with photoinitiated dimethacrylate monomers to create experimental resin infiltrants. ICON® (CN; DMG-America, Ridgefield Park, NJ) and pure resin (PR) were used as control groups in this study. Disc-shaped samples were prepared for the experimental and control groups. The samples were challenged with the pH cycle and immersed in the artificial saliva for 30 days. On Day 0 and Day 30, the pH cycle and artificial saliva immersion, Vicker's microhardness, surface roughness, and surface morphology were investigated. Results The RIF group's disc samples showed the highest Vicker's microhardness values (78.20 ±0.06) on Day 30 of artificial saliva immersion, whereas the CN group's values were the lowest (55.99 ±0.24). Following the pH cycling, the RIF displayed the highest hardness (64.15 ±1.89) whereas the CN group's values were the lowest (33.47 ±1.28). Regarding surface roughness, on Day 30, the RIB resin group exhibited the highest (1.14 ±0.001 µm). In contrast, the CN resin showed the lowest (1.07 ±0.06 µm) values, while immersed in the artificial saliva solution. In the same duration of time, in the pH cycling solution, PR showed the least (0.85 ±0.89 µm), while RIF showed the highest roughness value (0.94 ±0.54 µm). Morphological analysis revealed that following the artificial saliva immersion, the RIB, CN, and PR exhibited smoother surfaces compared to the RIS and RIF groups. However, when immersed in the pH cycling solution, RIB and RIF showed more resistance against acid attack. Conclusions Our results revealed that the experimental resin groups performed much better than the commercial resin infiltrants following artificial saliva and pH cycling challenges.

Surface Topography of Thermoplastic Appliance Materials Related to Sorption and Solubility in Artificial Saliva.

(1) Background: PETG (polyethylene terephthalate glycol) is a transparent, inexpensive, and versatile thermoplastic biomaterial, and it is increasingly being used for a variety of medical applications in dentistry, orthopedics, tissue engineering, and surgery. It is known to have remarkable properties such as tensile strength, high ductility, and resistance to chemical insults and heat, but it can be affected by various environmental conditions. The aim of the present study was to evaluate the topographical characteristics of four thermoplastic dental appliance materials in relation to water sorption in simulated oral environments (artificial saliva samples with different pH values). (2) Methods: The following four types of PETG clear thermoplastic materials were selected for the present study: Leone (L), Crystal (C), Erkodur (E), and Duran (D). In relation to the desiccation and water-uptake stages, their water sorption (Wsp) and solubility (Wsl) were calculated, and the surface topographies were analyzed on two length scales. The surface roughness was determined using a contact profilometer, and nanoroughness measurements were generated by three-dimensional profiles using an atomic force microscope (AFM). Statistical analyses (one-way ANOVA and unpaired and paired Student t-tests) were performed. (3) Results: After saliva immersion, the weights of all samples increased, and the highest sorption was recorded in a basic environment. Among the materials, the water uptake for the L samples was the highest, and for E, it was the lowest. In relation to water solubility, significant values were registered for both the L and C samples' materials. After immersion and desiccation, a decreasing trend in microroughness was observed. The AFM high-resolution images reflected more irregular surfaces related to saliva immersion. (4) Conclusions: The sorption rates recorded in water-based artificial saliva were higher for basic pH levels, with significant differences between the samples. There were also significant differences related to the behaviors of the materials included in the study. In relation to roughness, on a microscale, the surfaces tended to be smoother after the saliva immersions, and on a nanoscale, they became more irregular.

Color stability of CAD-CAM hybrid ceramic materials following immersion in artificial saliva and wine.

To examine the color stability of 3D-printed and milled, interim, and definitive, restorative materials after immersion in artificial saliva and wine for 1, 3, and 6 months. The study used a 2 × 5 factorial design with 10 subgroups, including 2 immersion liquids (artificial saliva and wine) and 5 manufacturing technology and restorative material combinations (n = 10). Color measurements were taken using a contact-type digital spectrophotometer (CM-2600d Spectrophotometer; Konica Minolta Healthcare Americas Inc) before immersion and at 1 month (T1), 3 months (T3), and 6 months (T6) after immersion. The CIE2000 system was used to calculate quantitative measurements of color differences in ΔE00, and comparisons were made to the acceptability threshold (AT) and perceptibility threshold (PT). Repeated measures of ANOVA (α = 0.05) were used to compare differences in color changes between manufacturing technology/restorative material-immersion liquid combinations at T1, T3, and T6. To compare the effect of immersion liquid and time on the manufacturing technology/restorative material groups, the ΔE00 values were compared to the PT of 0.8 and the AT of 1.8. Wine caused significant color changes in ΔE00 values beyond the PT and AT values in all groups at all time intervals, except for the AT value of milled definitive crowns (hybrid nano-ceramic material). Wine immersion caused significant ΔE00 for all manufacturing technology/restorative material groups at all time intervals (1 month, 3 months, and 6 months) when compared to artificial saliva immersion (all p < 0.001). Upon exposure to artificial saliva, 80%-100% of samples from all groups remained within the acceptable and perceptible color change thresholds. The wine had significant chromogenic effects on all tested restorative materials, however, the milled definitive crowns (hybrid nano-ceramic material) showed the greatest color stability. For patients with heavy wine consumption, 3D-printed definitive crowns (hybrid ceramic-filled material) may show discoloration exceeding acceptable and perceptible color change limits.

Biocompatibility of dental implants coated with hydroxyapatite using pulsed Er:YAG laser deposition.

We aimed to improve the biocompatibility and osteoinductive potential of Ti implants using a simulated intraoral hydroxyapatite (HAp) coating. We devised a novel surface treatment for aggressive induction of osteoblast adhesion and bone regeneration on the implant surface. A thin α-tricalcium phosphate (α-TCP) film was deposited on the implant surface using a pulsed Er:YAG laser. The coating was converted to HAp through artificial saliva immersion, which was confirmed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). SEM showed needle-like HAp crystals on the Ti disks and sandblasted implant surfaces after immersion in artificial saliva for 96 h. Microcomputed tomography and histological evaluation 4 and 8 weeks after implantation into beagle dog mandibles showed that the HAp-coated implant was biocompatible and exhibited superior osteoinduction compared to that of sandblasted implants. Coating the implant surface with HAp using an Er:YAG laser has potential as a new method of the implant-surface debridement.

In vitro assessment of dental erosion caused by clear aligners

The primary objective of this in vitro study was to investigate the erosive potential of enamel under the use of clear aligners (CA), by simulating in vivo conditions experienced by patients who do not remove their CA during the consumption of acidic beverages. In addition, the difference in erosion protection conferred by artificial and human saliva was also evaluated. Sound-extracted human premolars (n = 20) had half of their surfaces protected with acid-resistant nail polish and were randomly distributed into two experimental groups (n = 10): teeth immersed in human saliva or artificial saliva. All teeth had half of their lingual surfaces enclosed by a CA device. The erosive challenges consisted of individual immersion of each sample in citrus acid three times a day, intermediated by immersion in human saliva or artificial saliva for 2 h, during ten days of the erosive protocol. The enamel mineral content was analyzed by high-resolution microtomography. The differential mineral concentration profiles were obtained by subtracting the profile of the mineral concentration of the exposed area and enamel under the CA area from the respective sound area (control). In addition, enamel wear and enamel volume loss were measured. Scanning electron microscopy (SEM) was also performed to analyze the enamel surface. Data were analyzed by two-way ANOVA, followed by the Student-Newman-Keuls test. The enamel wear was higher in teeth immersed in artificial saliva, when compared to human saliva (p < 0.001). The volume loss of the exposed enamel area was lower for tooth immersed in human saliva than in artificial saliva (p < 0.001), during the acid challenge protocol. The use of CA during acid challenges promoted wear and mineral loss of dental enamel, being these changes more pronounced on the enamel surface under the CA. These results open a new path for the development of further studies adopting clinical protocols that promote more accurate responses in the clinical practice during orthodontic treatment.

The Effect of Se ect of Several Electric Cigar al Electric Cigarette Puffs on Nanohybrid ette Puffs on Nanohybrid Composite Resin Surface Roughness

Nanohybrid composite resin is a dental restorative material comprising micro and nano-sized fillers. When accompanied by smoking habits, it can alter the surface roughness of composite resin. Objective: This study aimed to determine the effect of several electric cigarette (e-cigarette) puffs on the surface roughness of nanohybrid composite resin. Methods: This study was conducted in the experimental laboratory with a pretest-posttest control group design using 48 nanohybrid composite resin specimens divided into six groups. Subsequently, the experimental groups were exposed to 75, 150, 225, 300, and 450 puffs of e-cigarette, and the control group was given artificial saliva immersion without exposure for 21 days. The surface roughness of specimens was measured with a surface roughness tester and evaluated through statistical analysis, including One-Way ANOVA and Post-Hoc LSD. Results: The average pre-test and post-test differences between groups I, II, III, IV, V, and VI were 0.013, 0.022, 0.033, 0.044, 0.065, and 0.005 μm. These results showed a significant difference in the surface roughness of nanohybrid composite resin (p &lt; 0.05), with variations between all groups. Conclusion: This study showed that the number of e-cigarette puffs had a significant effect on the surface roughness of nanohybrid composite resin. Specifically, an increase in the number of e-cigarette puffs led to a rise in the surface roughness value of nanohybrid composite resin.

Comparison of surface roughness and hardness of three different brands of esthetic coated NiTi archwires: invitro study

BackgroundThe purpose of the current in vitro study was to evaluate the surface roughness and hardness of three brands of as-received esthetic coated NiTi archwires and compare them with the same parameters after immersion in artificial saliva.MethodsThree groups of 0.016 × 0.022 inch epoxy-coated NiTi orthodontic wires [Tooth tone coated NiTi (Ortho Technology, West Columbia, USA), EverWhite NiTi (American Orthodontics, Wisconsin, USA) and Nitanium Super Elastic Tooth Tone Plastic coated (Ortho Organizers, San Marcos, CA, USA)] were compared. Each group was subdivided into five as-received archwire specimens and five archwire specimens retrieved following immersion in artificial saliva for 28 days. Atomic force microscopy was used for analysis of average surface roughness (Sa). Hardness testing was performed using Digital Vickers hardness tester. ANOVA and Kruskal-Wallis tests were used for comparing the wire groups.ResultsThe ranking of (Sa) values was as follows: Nitanium Ortho Organizers > Everwhite American Orthodontics > Tooth tone Ortho Technology (P > 0.05). Nitanium Ortho Organizers archwires showed significantly greater (Sa) than both other groups following immersion in saliva (P < 0.001). The coating hardness of as-received and post-immersion archwires from Tooth tone Ortho Technology was significantly lower than the other groups (P < 0.001). For all the three types of archwires, the mean hardness of immersed wires was significantly lower than that of the as-received archwires (P < 0.001).ConclusionsEsthetic coated archwires have shown unpleasant surface changes following exposure to artificial saliva. These surface changes are affected by physical characteristics such as surface roughness and hardness of the coating.

Physico-mechanical and antimicrobial properties of an elastomeric ligature coated with reduced nanographene oxide-nano curcumin subjected to dual-modal photodynamic and photothermal inactivation against Streptococcus mutans biofilms

BackgroundWhite spot lesions (WSLs) are a common side effect of fixed orthodontic treatment. Streptococcus mutans is the primary causative agent of WSLs and dental caries on the teeth during treatment. According to the unique features of reduced graphene oxide-nano curcumin (rGO-nCur), this study aimed to investigate the mechanical properties and antimicrobial potency of rGO-nCur coated orthodontic elastomeric ligatures as a novel coating composite following dual-modal photodynamic inactivation (PDI) and photothermal inactivation (PTI) against S. mutans biofilms. MethodsAfter confirmation of rGO-nCur synthesis and coating elastomeric ligatures with different concentration levels of 1.25, 2.5, 5, 7.5, and 10 % of rGO-nCur, tensile strength, force decay, extension to tensile strength, and contact angle of the coated elastomeric ligatures were measured using universal testing machine and sessile drop method, respectively. To investigate the mechanism through which irradiated rGO-nCur can inhibit the formation of S. mutans biofilms, intracellular reactive oxygen species (ROS) generation, and increase in temperature of rGO-nCur solutions under the 450 and 980 nm laser irradiation, respectively, were measured. The anti-biofilm activity and inhibition of water-insoluble extracellular polysaccharide (EPS) production ability of irradiated rGO-nCur coated elastomeric ligatures using a 450 nm diode laser (195 J/cm2), a 980 nm diode laser (195 J/cm2), and a combination of both (78 J/cm2 of irradiation from each one) (i.e., PDI, PTI, and dual-modal PDI/PTI, respectively) were determined. Also, the expression of virulence genes involved in biofilm formation (comDE, gtfD, and smuT) was assessed by quantitative real-time polymerase chain reaction (RT-qPCR) following the mentioned treatment. One-way ANOVA test and Tukey post-hoc test at a p-value equal to/or less than 0.05 were used to analyze the obtained data. ResultsThe synthesis of GO nano-sheets in a layered structure with a thickness of 0.76 nm was confirmed by AFM analysis. FESEM showed that the exfoliated sheet of synthesized GO had several micrometers in lateral size. DLS revealed that the mean particle size and density index of synthesized nCur were 57.47 ± 2.14 nm and 10 % respectively. In DLS analysis, rGO-nCur showed more positive surface charge (24 mV) than the nano-sheets of GO. FESEM confirmed the coating of rGO-nCur on elastomeric ligatures. ANOVA revealed that tensile strength of 1.25, 2.5, and 5 % rGO-nCur coated elastomeric ligatures were not decreased statistically significantly (P > 0.05). Mean tensile strength and recorded force of 7.5 and 10 % rGO-nCur coated elastomeric ligatures decreased significantly after 14 days’ immersion in the artificial saliva (P < 0.05). On the 28th day of the study, the mean of the tensile strength of elastomeric ligatures coated with 10 % rGO-nCur (13.03 ± 0.10 N) was recorded as 55.90 % of the initial tensile strength (23.31 ± 0.41 N in uncoated elastomeric ligatures), while the mean tensile strength of elastomeric ligatures coated with 7.5 % rGO-nCur (16.01 ± 0.10 N) was measured as 68.94 % of the initial tensile strength (23.22 ± 0.09 N in uncoated elastomeric ligatures). When comparing the coated elastomeric ligatures at 7.5 % and 10 % to the original uncoated elastomeric ligatures at similar time intervals, statistically significant decreases in extension to tensile strength (0.42 to 0.71 mm or 3.02 to 5.05 %; all P < 0.05) were observed. The largest contact angle was measured in elastomeric ligatures coated by 10 % rGO-nCur followed by 7.5 and 5 % rGO-nCur (128 ± 2.19°, 117 ± 2.23°, and 99 ± 1.83°; respectively). The results revealed a rise of 6.4-fold in intracellular ROS and an 11.2 °C increase in the temperature of rGO-nCur solutions following the 450 nm and 980 nm laser irradiation, respectively. The 5 % rGO-nCur coated elastomeric ligature mediated dual-modal PDI/PTI showed the most inhibition of the biofilm formation of S. mutans by 83.62 % (P = 0.00). Significant reductions in water-insoluble EPS were detected in biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 nm and 980 nm diode lasers (i.e., dual-modal PDI/PTI; 96.17 %; P = 0.00). The expression levels of comDE, gtfD, and smuT virulence genes were significantly downregulated (7.52-, 13.92-, and 8.23-fold, respectively) in the biofilm cultures of S. mutans on 1.25 % rGO-nCur coated elastomeric ligatures following dual-modal PDI/PTI in comparison with biofilm cultures on non-coated elastomeric ligatures. Conclusion5 % rGO-nCur coated elastomeric ligatures following irradiation with dual waves of the 450 and 980 nm diode lasers (dual-modal PDI/PTI), without adverse effects on the physico-mechanical properties of elastomeric ligatures, can be used to inhibit the formation of S. mutans biofilms on the coated elastomeric ligatures around orthodontic brackets.

Synthesis of films based on chitosan and protic ionic liquids to be used as wound dressing on the oral mucosa

Oral mucosal ulcerations expose connective tissue to different pathogens and this can progress to systemic infection. This study aimed to synthesize environmentally-friendly films with chitosan and protic ionic liquids, possessing mucoadhesive properties, activity against opportunistic microorganisms, enhanced malleability and mechanical resistance to be used as a wound dressing on the oral mucosa. Therefore, films with chitosan and 10, 35, and 50 % (wt/wt) of 2-hydroxy diethylammonium lactate, salicylate, and maleate protic ionic liquids were synthesized. Thickness measurements and mechanical properties analysis were performed. In addition, oral mucoadhesion, antimicrobial activity, and cytotoxicity properties were investigated. Results showed that the addition of 35wt% and 50wt% of all kinds of protic ionic liquids tested presented significant improvements in film thickness and mechanical properties. Films based on chitosan and the protic ionic liquid 2-hydroxy diethylammonium salicylate at percentages of 35 and 50wt% exhibited superior mucoadhesive properties, antimicrobial activity on opportunistic microorganisms and an improvement in their flexibility after immersion in synthetic saliva. Cytotoxicity results suggest that all kinds of chitosan/protic ionic liquids films tested are safe for intra-oral use. Therefore, the results of this study indicate that these materials could be good candidates for efficient and environmentally-friendly wound dressing films on the oral mucosa.

Effect of acidic saliva on monomer leaching and surface roughness of 3D-printed and milled denture-base materials

The study evaluated the effect of different acidic salivary pH values on monomer leaching and surface roughness of conventional and CAD/CAM processed (milled and 3D-printed) denture base materials. High-performance liquid chromatography was used to determine the quantity of residual methyl methacrylate monomer leaching after 30 days of immersion in acidic saliva. The surface roughness (Ra) before and after incubation was recorded using a non-contact optical profilometer. The monomer leaching and the surface roughness of the tested materials depended on the pH value of the saliva. The conventional denture framework material exhibited the highest and lowest leaching rates at pH=4.5 and pH=3.5, respectively, regardless of the treatment method. Among the CAD/CAM processed materials, the 3D-printed material showed the highest and lowest leaching at pH=5.5 and pH=3.5, respectively. Regardless of the pH, roughness after incubation was the lowest for conventional materials, and the highest for 3D printing.

Influence of violet LED and fluoride-containing carbamide peroxide bleaching gels on early-stage eroded/abraded teeth

PurposeThis study evaluated enamel with early-stage erosion/abrasion following bleaching with 20% and 45% carbamide peroxide (CP) gels containing fluoride (F) and irradiated with violet LED (LED). MethodsEnamel blocks were immersed in 1% citric acid (5 min) and artificial saliva (120 min) three times to produce early-stage enamel erosion. Simulated toothbrushing was performed only after the first saliva immersion, to provoke enamel abrasion. The erosive/abraded enamel samples were submitted to (n=10): LED/CP20, CP20, LED/CP20_F, CP20_F, LED/CP45, CP45, LED/CP45_F, CP45_F, LED, and control (without treatment). The pH of the gels was assessed, and color (ΔE00) and whiteness index (ΔWID) changes were calculated after cycling (T1), and 7 days from bleaching (T2). Enamel surface roughness average (Ra) and Knoop microhardness (kg/mm2, %SHR) were evaluated at baseline (T0) at T1 and T2. Scanning electron microscopy evaluated the enamel surface morphology at T2. ResultsThe gels’ pH was neutral and CP20 and CP45 exhibited no differences in ΔE00 and ΔWID (p>0.05) but LED increased these parameters for CP20_F and CP45. Erosion/abrasion significantly decreased mean kg/mm2, and the LED group was the only one not increasing microhardness after bleaching (p>0.05). None of the groups fully recovered the initial microhardness. All groups exhibited %SHR similar to the control (p>0.05) and the increase in Ra was detected only after erosion/abrasion. CP20_F groups exhibited a more preserved enamel morphology. ConclusionLight irradiation combined with low-concentrated CP gel promoted a bleaching effect comparable to the high-concentrated CP. The bleaching protocols did not adversely impact the surface of early-stage eroded/abraded enamel.

In Vitro Degradation of Mg-Doped ZrO2 Bioceramics at the Interface with Xerostom® Saliva Substitute Gel

Zirconia-based bioceramics, one of the most important materials used for dental applications, have been intensively studied in recent years due to their excellent mechanical resistance and chemical inertness in the mouth. In this work, the structural, morphological and dissolution properties of the Zr1-xMgxO2 (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) system, prepared by the conventional ceramic method, were evaluated before and after immersion in saliva substitute gel (Xerostom®, Biocosmetics Laboratories, Madrid, Spain), one of the most common topical dry mouth products used in dentistry. The X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) techniques were employed to investigate the phase transformations and morphology of the ceramics during the degradation process in Xerostom®. In vitro analyses showed overall good stability in the Xerostom® environment, except for the x = 0.05 composition, where significant t- to m-ZrO2 transformation occurred. In addition, the strong interconnection of the grains was maintained after immersion, which could allow a high mechanical strength of the ceramics to be obtained.

THE RELEASE OF FLUORIDE IONS OF BIOACTIVE RESIN IN THE SOLUTION OF LACTIC ACID AND ARTIFICIAL SALIVA

Background: Bioactive resin can release fluoride ions when contact with oral environment. In the oral cavity, saliva and metabolic results of Streptococcus mutans namely lactic acid may affect the release of ions due to pH changes. Purpose: to analyse the release of fluoride ions of bioactive resin in the solution of lactic acid and artificial saliva. Methods: Forty-two specimens (diameter 15 mm x thickness 1 mm; n= 7/group fabricated with Activa™ Bioactive Restorative (Pulpdent). The specimen swere randomized into six 6 groups which immersed in lactic acid, artifial saliva and distilled water for 1 and 7 days in the incubator at 37oC. The number of fluoride ion release was measured using pH Meter (Lutron-208). Results: Two Way Anova test and Post Hoc Bonferonni test show there are significant differences among all group for lactic acid 1 day (6.37 ± 0.74), artificial saliva 1 day (1.30 ± 0.48), distilled water 1 day (3.78 ± 0.97), lactic acid 7 days (22.9 ± 0.81), artificial saliva 7 days (19.00 ± 0.81), distilled water 7 days (21.60± 1.01) ppm. Conclusion: The fluoride ion release of bioactive resin which immersed in lactic acid solution was higher than in artificial saliva immersion. Keywords: Artificial saliva, Bioactive resin, Fluoride ion release, Lactic acid

Nickel ion release of niti archwire in variations of immersion time and toothpaste

Nickel-titanium archwires in orthodontic wires have nickel ion releases. The use toothpaste and saliva immersion time may cause its releases. This study aims to prove the difference and interaction between immersion time and toothpaste variations towards the amount of nickel ion releases at nickel-titanium archwires. The study was an experimental research with a post-test only control group design. Twenty seven nickel-titanium archwires were divided into three groups, i.e., K group, which were immersed in artificial saliva. P1 was immersed in artificial saliva and 1.5 gram of toothpaste A, and P2 was immersed in artificial saliva, and 1.5 gram of toothpaste B. The samples were incubated (37 °C) for 1 and 1.5 months. Nickel ion released was analyzed using SSA. Two Way ANOVA and Post Hoc LSD test were the statistic test used. The results of this study were the K group which released 0.112 mg/l and 0.685 mg/l, P1 which released 0.093 mg/l and 0.670 mg/l, and P2 which released 0.099 mg/l and 0.657 mg/l. There were differences in toothpaste variations (p = 0.029), differences in immersion time (p = 0.000) and there was no interaction between immersion time and toothpaste variations (p = 0.505) on the amount of nickel ion release. There was a significant difference in K-P1 (p = 0.038), K-P2 (p = 0.013), P1-P2 (p = 0.049). There was a difference in immersion time and toothpaste variation, but there was no interaction between immersion time and toothpaste variation towards the amount of nickel ion releases.

Influence of Acidic Environment on the Hardness, Surface Roughness and Wear Ability of CAD/CAM Resin-Matrix Ceramics.

This study aimed to measure the effect of storage environment on the hardness, surface roughness and wear ability of CAD/CAM resin-matrix ceramics. A total of 200 rectangular-shaped specimens were obtained by sectioning 5 CAD/CAM blocks; Crystal Ultra (CU), Vita Enamic (VE), Lava Ultimate (LU), Cerasmart (CS) and Vita blocks Mark II (MII). Microhardness and surface roughness were measured at baseline and after 7 days of immersion either in saliva or cola (n = 10). The wear ability of the CAD/CAM materials against steatite-ceramics antagonist was determined using a chewing simulator. The data were statistically analyzed using factorial ANOVA followed by post hoc Bonferroni multiple comparison tests (p < 0.05). The independent factors significantly influenced the microhardness and surface roughness (p < 0.05). The highest VHN was observed in MII at baseline (586.97 ± 13.95), while CU showed the lowest VHN after 7 days of immersion in cola (68.3 ± 1.89). On the contrary, the highest Ra was observed after 120,000 chewing cycles for the VE specimens (1.09 ± 0.43 µm) immersed in cola, while LU showed the lowest Ra at baseline (0.07 ± 0.01 µm). The highest % mass loss of the antagonist was observed with MII immersed in cola (1.801%), while CS demonstrated the lowest % mass loss of 0.004% and 0.007% in AS and cola, respectively. This study confirms that the surface properties of tested CAD/CAM materials are susceptible to degradation in an acidic environment except for hardness and wear of CS material.

Surface Functionalisation of Dental Implants with a Composite Coating of Alendronate and Hydrolysed Collagen: DFT and EIS Studies.

The success of the osseointegration process depends on the surface characteristics and chemical composition of dental implants. Therefore, the titanium dental implant was functionalised with a composite coating of alendronate and hydrolysed collagen, which are molecules with a positive influence on the bone formation. The results of the quantum chemical calculations at the density functional theory level confirm a spontaneous formation of the composite coating on the titanium implant, ∆G*INT = −8.25 kcal mol−1. The combination of the results of X-ray photoelectron spectroscopy and quantum chemical calculations reveals the structure of the coating. The alendronate molecules dominate in the outer part, while collagen tripeptides prevail in the inner part of the coating. The electrochemical stability and resistivity of the implant modified with the composite coating in a contact with the saliva depend on the chemical nature of alendronate and collagen molecules, as well as their inter- and intramolecular interactions. The formed composite coating provides a 98% protection to the implant after the 7-day immersion in the artificial saliva. From an application point of view, the composite coating could effectively promote osseointegration and improve the implant’s resistivity in contact with an aggressive environment such as saliva.

The effect of phytosphingosine associated with tooth brushing on color change, surface roughness, and microhardness of dental enamel - an in vitro and in situ study.

This study evaluated the in vitro and in situ effects of phytosphingosine (PHS) associated with tooth brushing on color stability, surface roughness, and microhardness of dental enamel. Sixty-four specimens of bovine teeth (6 × 6 × 2mm) were separated into 8 groups (n = 8): S + TB: PHS (spray) + tooth brushing; TB + S: tooth brushing + PHS (spray); I + TB: PHS (immersion) + tooth brushing; TB + I: tooth brushing + PHS (immersion); TB: tooth brushing; S: PHS spray; I: immersion in PHS solution, and Saliva: immersion in saliva. Tooth brushing simulation (Mavtec, Brazil) was performed (356rpm on 3.8cm area by the toothbrush - Soft Tek) for 1, 7, 15, and 30days. PHS remained in contact with specimens for 15min. The specimens were evaluated before and after tooth brushing for color alteration (Easy Shade, VITA), and surface roughness (Model SJ-201P Mitutoyo), and Knoop microhardness (HMV-2, Shimadzu Corporation). For the in situ analyses, 8 participants were recruited and received an intraoral device with 6 fragments of bovine enamel (6 × 6 × 2mm). The properties evaluated were the same as those of the in vitro study. Participants were randomized following best results of in vitro tested protocols, for 15days: TB, TB + S, I + TB. Data obtained by in vitro (two-way ANOVA, Tukey, p < .05) and in situ (one-way ANOVA, Tukey, p < .05) studies were analyzed. The in vitro study showed that greater color change was found after 30days. The greatest differences in surface roughness occurred between the initial value and after 1day. Regarding microhardness, the highest values occurred after 15 and 30days, which showed similar results. The in situ study showed greater color changes for the TB and I + TB, and greater surface roughness changes for TB as well as a similar increase in microhardness for the PHS protocols, which were higher than TB. Phytosphingosine leads to an increase in performance regarding color stability, surface roughness, and microhardness when applied. In general, the application of PHS after brushing showed a positive impact on its performance. Phytosphingosine proved to be interesting for compound prevention formulations in the dentistry field.