Fresh Human Saliva Research Articles

Can Sodium Ascorbate Increase the In Vitro Bond Strength of the Interface between a Composite and Bleached Enamel?

Recently, the use of antioxidants before the bonding of bleached enamel was considered effective for reversing the reduction in the bond strength. This article aimed to assess the influence of different sodium ascorbate (SA) presentations (liquid, gel, and semi-gel) on the composite resin–enamel bond strength after a bleaching protocol. Sound human anterior teeth were collected, cleaned, prepared for a bond strength test, and randomly allocated into groups according to the bonding procedure. Group 1 acted as a control, without bleaching treatment, and without applying an antioxidant agent. In groups 2–6, specimens were bleached using 10% carbamide peroxide. In groups 3, 4 and 5, 10% wt% SA was applied for 10 min as an antioxidant in the form of a liquid, gel, and semi-gel, respectively. In group 6, samples were bleached and immersed in fresh human saliva for 14 days. After the bleaching process, the materials were restored by means of an adhesive system and a resin composite material. The analysis revealed that the differences between the shear bond strength (SBS) between the different groups were statistically significant (p = 0.0469). The highest SBS was achieved for the group where the 10 wt% SA liquid was applied before the bonding procedures. The application of liquid 10 wt% SA might reverse the negative impact that bleaching has on the bond strength of a resin composite and enamel.

Optical imaging spectroscopy for rapid, primary screening of SARS-CoV-2: a proof of concept

Effective testing is essential to control the coronavirus disease 2019 (COVID-19) transmission. Here we report a-proof-of-concept study on hyperspectral image analysis in the visible and near-infrared range for primary screening at the point-of-care of SARS-CoV-2. We apply spectral feature descriptors, partial least square-discriminant analysis, and artificial intelligence to extract information from optical diffuse reflectance measurements from 5 µL fluid samples at pixel, droplet, and patient levels. We discern preparations of engineered lentiviral particles pseudotyped with the spike protein of the SARS-CoV-2 from those with the G protein of the vesicular stomatitis virus in saline solution and artificial saliva. We report a quantitative analysis of 72 samples of nasopharyngeal exudate in a range of SARS-CoV-2 viral loads, and a descriptive study of another 32 fresh human saliva samples. Sensitivity for classification of exudates was 100% with peak specificity of 87.5% for discernment from PCR-negative but symptomatic cases. Proposed technology is reagent-free, fast, and scalable, and could substantially reduce the number of molecular tests currently required for COVID-19 mass screening strategies even in resource-limited settings.

In-Mouth Volatile Production from Brassica Vegetables (Cauliflower) and Associations with Liking in an Adult/Child Cohort.

Interactions between Brassica vegetables and human saliva can affect in-mouth odor development, which in turn may be linked to individual perception and liking. S-Methyl-l-cysteine sulfoxide is a unique substrate present in Brassicas that produces odor-active sulfur volatiles due to the activity of enzymes present in plant tissue and due to bacteria, which may be present to varying extents in an individual's oral microbiome. Proton transfer reaction mass spectrometry was applied to measure individual differences in sulfur volatile production in real time when fresh human saliva was incubated ex vivo with raw cauliflower for a cohort of child-adult pairs. Large differences in the rate of sulfur volatile production were measured between individuals, but not between age groups. Significant positive relationships were found for volatile production between the adult-child pairs, suggesting a degree of commonality in saliva composition and oral microbiome activity. Furthermore, significant negative relationships were measured between the amount of in-mouth sulfur volatile production and liking for raw cauliflower in children.

Post-synthesis modification of covalent organic frameworks for ultrahigh enrichment of low-abundance glycopeptides from human saliva and serum

In this study, a novel type of covalent organic framework (COF) material rich in boronic acid sites was prepared through post-synthesis modification (TbBD@PEI@Au@4-MPBA). The surface of COF material had abundant carboxylic acid groups, which could bind a large amount of polyethyleneimine (PEI) through electrostatic interaction. At the same time, the amino groups on the PEI can be grafted with Au nanoparticles (Au NPs) in situ, and then 4-mercaptophenylboronic acid (4-MPBA) was modified by the reaction of Au and sulfhydryl groups. The massive grafting of boronic acid groups made the material's enrichment effect on glycopeptides expected. The results of experiments indicated that the composite material has high sensitivity (5 amol μL−1) and selectivity (1:1000). In addition, the material has outstanding stability and reusability, with a load capacity of about 100 mg g−1 and a recovery of 99.3 ± 2.2%. What's more, after enriched by TbBD@PEI@Au@4-MPBA, 56 endogenous glycopeptides from fresh human saliva were detected by MALDI-TOF MS, 56 unique glycopeptides corresponding to 31 glycoproteins from human saliva and 513 unique glycopeptides corresponding to 208 glycoproteins from serum of throat cancer patient were detected by nano-LC-MS/MS, respectively, which was expected to be applied to glycoproteomics research.

Bacterial Leakage of Four Endodontic Sealers Using Fresh Human Saliva.

Bacterial leakage plays a considerable role in endodontic related failures. The aim of this study was to compare the bacterial leakage of bioceramic (including Well Root ST and MTA Fillapex) and resin-based root canal sealers (naming AH-Plus and AdSeal). Sixty-eight maxillary central incisors were included in this experimental study. These were randomly allocated into four experimental groups, which were obturated with gutta-percha and four different sealers (n=15), and the two control groups (positive, n=4 and negative, n=4). A dual-chamber technique was carried out using fresh human saliva and traced for 90 days. The Chi-square and Long Rank tests were performed for data analysis. Bacterial leakage was observed in 33.3% of the samples in Well Root ST, 40% in AH-Plus group, 53.3% in AdSeal group, and 66.6% in MTA Fillapex group. The difference between the Well Root ST and MTA Fillapex groups was significant (P=0.02). The mean leakage time between the Well Root ST (85.6 days) and MTA Fillapex groups (71.2 days) was also significant (P=0.037). The results of this in vitro study revealed bacterial leakage in all experimental groups. The Well Root ST and the MTA Fillapex groups showed the lowest and highest bacterial leakages, respectively. Then it seems that the Well Root ST is a good substitute for MTA Fillapex in clinical applications.

Oral Wine Texture Perception and Its Correlation with Instrumental Texture Features of Wine-Saliva Mixtures.

Unlike solid food, texture descriptors in liquid food are scarce, and they are frequently reduced to the term viscosity. However, in wines, apart from viscosity, terms, such as astringency, body, unctuosity and density, help describe their texture, relating the complexity and balance among their chemical components. Yet there is uncertainty about which wine components (and their combinations) cause each texture sensation and if their instrumental assessment is possible. Therefore, the aim of the present work was to study the effect of wine texture on its main components, when interacting with saliva. This was completed by using instrumental measurements of density and viscosity, and by using two types of panels (trained and expert). For that, six different model-wine formulations were prepared by adding one or multiple wine components: ethanol, mannoproteins, glycerol, and tannins to a de-alcoholised wine. All formulations were mixed with fresh human saliva (1:1), and their density and rheological properties were measured. Although there were no statistical differences, body perception was higher for samples with glycerol and/or mannoproteins, this was also correlated with density instrumental measurements (R = 0.971, p = 0.029). The viscosity of samples with tannins was the highest due to the formation of complexes between the model-wine and salivary proteins. This also provided astringency, therefore correlating viscosity and astringency feelings (R = 0.855, p = 0.030). No correlation was found between viscosity and body perception because of the overlapping of the phenolic components. Overall, the present results reveal saliva as a key factor when studying the wine texture through instrumental measurements (density and viscosity).

Influence of saliva on individual in-mouth aroma release from raw cabbage (Brassica oleracea var. capitata f. rubra L.) and links to perception

Raw or minimally processed vegetables are popular for health reasons and for their unique textural and flavor attributes. While many aroma volatiles are produced in situ when plant tissues are mechanically disrupted, enzymes expressed in bacteria in oral microbiota such as cysteine-β-lyase (EC 4.4.1.13) may also contribute to aroma formation in-mouth during consumption. Interactions between raw cabbage and fresh human saliva (n = 21) were measured ex vivo by real-time monitoring of sulfur volatile production by proton transfer reaction mass spectrometry (PTR-MS). Inter-individual differences in the concentration of sulfur volatiles from the breakdown of S-methyl-L-cysteine sulfoxide (SMCSO) in fresh cabbage by saliva were characterized and a 10-fold difference in the extent of sulfur volatile production was measured across individuals. The overall intensity and garlic odor of raw cabbage was positively correlated with the concentration of sulfur volatiles after incubation with fresh human saliva. A buildup of SMSCO-derived sulfur volatiles in vivo, over twenty repeated mouthfuls was demonstrated, indicating that these reactions can affect sensory perception within the timescale of eating. These findings show the perceived odor experienced when eating cabbage differs, thus resulting in a unique flavor experience between individuals.

Effect of saliva esterase activity on ester solutions and possible consequences for the in-mouth ester release during wine intake.

The aim of this study was to investigate the role of saliva esterase activity on carboxylic esters typically associated with pleasant and fruity aromas in wine. For this, ex vivo experiments using the same fresh and inactivated (without enzymatic activity) human saliva with a mixture of carboxylic esters with different aliphatic chain length (ethyl butanoate, ethyl pentanoate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, and isoamyl acetate) were prepared. Liquid-liquid extraction with dichloromethane and GC-MS analysis were applied to the saliva systems in order to determine the reduction in ester content and the formation of their corresponding metabolic products (carboxylic acids) in the saliva systems before and after incubation at 37C. In addition, to check if there was a relationship between the susceptibility of esters to saliva hydrolysis and the amount of in-mouth ester release during wine intake, the remaining oral amount of each ester was determined by comparing the intraoral amount immediately after spitting out the wine and 4 min later. Ex vivo experiments showed ester degradation by saliva esterase enzymes mainly acted on long chain esters (ethyl octanoate and ethyl decanoate), which gave rise to the formation of their corresponding carboxylic acids. Nonetheless, in spite of their higher susceptibility to saliva enzymes, in vivo experiments showed that long chain carboxylic esters remained in the oral cavity long after swallowing. This confirmed that ester hydrophobicity is closely related to the in-mouth temporal release of these odorants and, therefore, behind wine aroma persistence. In wines, esters represent a group of aromatic compounds of great interest since they are linked to pleasant fruity aroma nuances. Today wine consumers are demanding fresh and long persistent fruity aromatic wines. The present research contributes to better understanding the relationship between ester content in the wine and oral aroma release experienced during wine tasting, considering the changes in these compounds during oral processing. This is a necessary step when trying to unravel the factors involved in wine aroma perception and in consumer preferences, and it represents a necessary knowledge in promoting winemaking practices (e.g., the use of selected microorganisms) for improving the type and amount of these aroma compounds in the wine.

Effect of cleaning methods on retentive values of saliva-contaminated implant-supported zirconia copings.

The aim of this study was to evaluate the effect of different cleaning regimens on retentive strength of saliva-contaminated implant-supported zirconia copings. Seventy solid titanium abutments with 5.5mm height (Straumann) were attached to the regular neck implant analogs (Straumann). The abutment-analog complex was mounted vertically in an autopolymerized T-shaped acrylic resin block. Seventy zirconia copings with an occlusal loop were made. The copings were contaminated with fresh human saliva for 1min (except the control group). Afterward, the specimens were washed with water spray for 15s and dried for 15s. The copings were divided into seven groups according to cleaning methods (n=10). Group 1: no contamination (control group); Group 2: water spray rinsing; Group 3: airborne particle abrasion; Group 4: immersion in 96% isopropanol; Group 5: applying Ivoclean (Ivoclar Vivadent); Group 6: applying 1% sodium hypochlorite; and Group 7: applying Monobond Plus (Ivoclar Vivadent). The copings were luted with a resin luting agent (RelyX Unicem; 3M ESPE). After 5,000 thermal cycles, the retentive values of the restorations were tested using universal testing machine. The dislodging forces were analyzed using one-way analysis of variance and the Tukey's HSD tests (α=0.05). The copings, which were cleaned with Ivoclean and 96% isopropanol, showed the highest retentive values (204.79±44.49 and 232.65±71.36, respectively). There was a significant difference between the studied groups (F=2.735; p=.02). Tukey's HSD showed that there was no significant difference between the different cleaning procedures and control group except water rinsing group (p=.14). The lowest retentive value was related to the saliva-contaminated group, which were only cleaned with water rinsing method. The retentive values of zirconia-based restorations were adversely affected by saliva contaminations. These restorations can be cleaned by Ivoclean, 96% isopropanol, airborne particle abrasion, 1% sodium hypochlorite, or applying Monobond Plus before luting procedures.

Effect of saliva contamination and artificial aging on different primer/cement systems bonded to zirconia

Statement of problemSaliva contamination has been shown to decrease bonding to zirconia. Adopting a less contamination-sensitive cement system may be an alternative to decontamination. PurposeThe purpose of this in vitro study was to assess the ability of different primer/cement systems to promote a durable bond to zirconia after saliva contamination. Material and methodsZirconia blocks (Lava Plus) (N=320) were airborne-particle abraded (50 μm Al2O3) and divided into 32 experimental groups (n=10) according to the variables in the study: saliva contamination; primer/cement system (Panavia SA [PSA]; RelyX Unicem 2 [RU2]; Bifix SE [BSE]; Panavia F2.0 [PF2]; Scotchbond Universal + RelyX Ultimate [SBU+RXU]; Futurabond M+ + Bifix QM [FBM+BQM]; All-Bond Universal + Duo-link [ABU+DL]; Z-Prime Plus + Duo-link [ZPP+DL]; and aging period (72 hours; 30 days with 10 000 thermocycles at 5°C to 55°C). After half of the blocks had been contaminated with fresh human saliva for 10 minutes, rinsed with water, and air-dried, each primer/cement was applied. Polymerized composite resin disks were then placed over the cement, and the resin cement was light-polymerized for 20 seconds each at 2 opposite margins. After the aging time, the specimens were tested in shear (1 mm/min). The failure mode was classified as adhesive, cohesive, or mixed. Statistical analysis of the shear bond strength (SBS) data was performed with ANOVA followed by Tukey honest significant difference post hoc tests. Chi-square tests were used to analyze the failure mode data (α=.05). ResultsThe mean SBS ranged between 4.2 and 34.5 MPa. Shear bond strength was influenced (P<.001) by all the factors studied (cement system, saliva contamination, aging time). SBU+RXU and FBM+BQM showed a higher mean SBS than those of the other experimental groups (P<.05) and were the only groups not affected by saliva contamination (P>.05). Failure was predominantly classified as adhesive. ConclusionsIn general, saliva contamination and aging decreased bonding efficacy. Two systems, combining an application of a universal adhesive and a resin cement (SBU+RXU and FBM+BQM) were not affected by saliva contamination.

The Effect of Chlorhexidine Mixed with Mineral Trioxide Aggregate on Bacterial Leakage of Apical Plug in Simulated Immature Teeth Using Human Fresh Saliva.

Objectives:Apexification is a challenging treatment in necrotic open apices teeth and bacterial leakage is the main reason for the treatment failure. The aim of this study is to compare the effect of mixing mineral trioxide aggregate (MTA) with chlorhexidine (CHX) on microbial leakage in apexification treatment of simulated immature teeth.Materials and Methods:In this experimental study, 44 intact central incisors were selected based on inclusion criteria. The coronal and 2 mm of apical part of the specimens were removed till all root segments were 12 mm long. The apical parts of the teeth were prepared using Profile #40/0.06 (Dentsply Maillefer, Ballaigues, Switzerland) in the apical to coronal direction to simulate open apices. The specimens were separated into experimental groups (n = 40) and control groups (n = 4). Group 1 delivered a 5 mm apical plug by MTA/H2O and group 2 delivered an apical plug by MTA/CHX 0.12%. The positive control group had no apical barrier; on the other hand, the negative control group had an apical barrier and two layers of nail varnish on entire root surface. The microbial leakage assessment was done by a dual-chamber apparatus using fresh human saliva after 10-week follow-up. The turbidity of the lower chamber containing the Brain Heart Infusion (BHI) solution was analyzed based on the McFarland (0.5) standard which utilizes spectrophotometry results. Data analyses were done using Chi-square, Kaplan–Meier, and log-rank tests.Results:MTA/CHX group had lower microbial leakage percentage (P = 0.001) and longer time of leakage (P = 0.002) in compared with MTA/H2O group and the difference was statistically meaningful.Conclusion:Based on the results of this study, MTA/CHX mixture can reduce the amount of bacterial leakage.

Evaluation of Four Different Denture Cleansers on Tea Stain Removal from Heat Cure Clear Acrylic Resin Specimens—An In Vivo Study

The rough and pitted surfaces seen on acrylic dentures act as niduses for biofilm formation and colonization of microorganisms. Denture cleansers are the most preferred for chemical cleansing, which has been suggested for the disinfection of prostheses. The aim of the study was to evaluate four different denture cleansers on tea stain removal from heat cure clear acrylic resins (DPI heat cure) material. Forty clean acrylic specimens of dimensions 40 mm × 20 mm × 1 mm were fabricated. The samples were then placed in fresh human unstimulated saliva for 2 min to form an initial pellicle layer and facilitate the uptake of stain, and they were washed with water. The samples were divided into 4 batches of 10 each. One-way ANOVA, Tukey’ HSD, and Students’ paired t-test were employed to identify the significant groups at 5% level. The mean value in Batch C, i.e., using Clinsodent powder (0.62 ± 0.32), was significantly higher than the mean values in Batch A, i.e., using Corega Bio Tabs (0.34 ± 0.14), Batch B, i.e., using fitty dent tabs (0.19 ± 0.19), and Batch D, i.e., using Steradent powder (0.25 ± 0.11) (p < 0.05). This study revealed that all the four immersion denture cleansers were effective in removing the tea stains from heat cure acrylic resins. Among the four cleansers, Clinsodent powder removed the tea stains to the greatest extent.

Habituation of adult sea lamprey repeatedly exposed to damage-released alarm and predator cues

Predation is an unforgiving selective pressure affecting the life history, morphology and behaviour of prey organisms. Selection should favour organisms that have the ability to correctly assess the information content of alarm cues. This study investigated whether adult sea lamprey Petromyzon marinus habituate to conspecific damage-released alarm cues (fresh and decayed sea lamprey extract), a heterospecific damage-released alarm cue (white sucker Catostomus commersonii extract), predator cues (Northern water snake Nerodia sipedon washing, human saliva and 2-phenylethylamine hydrochloride (PEA HCl)) and a conspecific damage-released alarm cue and predator cue combination (fresh sea lamprey extract and human saliva) after they were pre-exposed 4 times or 8 times, respectively, to a given stimulus the previous night. Consistent with our prediction, adult sea lamprey maintained an avoidance response to conspecific damage-released alarm cues (fresh and decayed sea lamprey extract), a predator cue presented at high relative concentration (PEA HCl) and a conspecific damage-released alarm cue and predator cue combination (fresh sea lamprey extract plus human saliva), irrespective of previous exposure level. As expected, adult sea lamprey habituated to a sympatric heterospecific damage-released alarm cue (white sucker extract) and a predator cue presented at lower relative concentration (human saliva). Adult sea lamprey did not show any avoidance of the Northern water snake washing and the Amazon sailfin catfish extract (heterospecific control). This study suggests that conspecific damage-released alarm cues and PEA HCl present the best options as natural repellents in an integrated management program aimed at controlling the abundance of sea lamprey in the Laurentian Great Lakes.

Bond Strength of a Bisphenol-A-Free Fissure Sealant With and Without Adhesive Layer under Conditions of Saliva Contamination

Dental sealants are important for prevention of carious lesions, if they have good shear strength. The aim of this study was to evaluate the shear bond strength (SBS) of two sealants to saliva-contaminated and non-contaminated enamel with and without an intermediate adhesive layer underneath the sealant. Ninety flat enamel surfaces from human third molars were randomly assigned to 6 groups (n=15): F (control): Fluroshield(tm) sealant; EWB (control): Embrace(tm) WetBond(tm); SB/F: Single Bond adhesive system + F; SB/EWB, s-SB/F and s-SB/EWB. In the s-SB/F and s-SB/EWB groups, the acid-etched enamel was contaminated with 0.01 mL of fresh human saliva for 20 s. Sealant cylinders were bonded to enamel surface with and without an intermediate adhesive system layer. The shear tests were performed using a universal testing machine (0.5 mm/min). Data were analyzed statistically by Kruskal-Wallis and Mann-Whitney tests (α=0.05). F presented higher mean SBS than EWB in all experimental conditions. The lowest SBS mean was obtained for EWB on contaminated enamel (p<0.05). In conclusion, an adhesive system layer should be used prior to sealant placement, in both dry and saliva-contaminated enamel. F had the best performance in all experimental conditions. EWB sealant showed very low results, but an adhesive layer underneath the sealant increased its SBS even after salivary contamination.

Comparison of Microleakage and Penetration Depth between Hydrophilic and Hydrophobic Sealants in Primary Second Molar

IntroductionOptimal pit and fissure sealing is determined by surface preparation techniques and choice of materials. The performance of pit and fissure sealant materials has been intensively investigated, yet no single product is reported as an ideal sealant. In children, moisture control during cavity preparation is always a big challenge, and hence, hydrophilic sealants have been developed.AimTo compare the microleakage and penetration depth of hydrophilic and hydrophobic sealants using acid-etching on dry and moist surfaces.Materials and methodsRecently, extracted 28 2nd primary molars are assigned to two groups (hydrophobic group I; hydrophilic group II) depending on the surface condition (dry group: A1 and B1; moist group: A2 and B2) of 7 teeth in each group. Samples from group A1 and B1 are cleaned and dried with a 3-way syringe and etched with etching gel, and sealant is applied to the fissures and cured with visible light. Sample from A2 and B2 are immersed in 0.1 mL of fresh whole human saliva for 20 seconds and dried using a pellet cotton, and the same procedure is carried out. All samples are subjected to 1000 thermal cycles and sectioned to compare the depth of penetration and microleakage. Sections will be examined under light microscope and analyzed using an image analysis software (SigmaScan).ResultsThe least microleakage was seen with hydrophilic sealant under moist surface condition, and the depth of penetration of hydrophobic sealant was found to be better than that of hydrophilic sealant in both dry and moist surface conditions.ConclusionHydrophilic pit and fissure sealants showed higher tolerance to saliva contamination with less microleakage, but in terms of penetration ability hydrophobic sealants were found to be superior.How to cite this articleGawali PN, Chaugule VB, Panse AM. Comparison of Microleakage and Penetration Depth between Hydrophilic and Hydrophobic Sealants in Primary Second Molar. Int J Clin Pediatr Dent 2016;9(4):291-295.

Effect of fluid contamination on reverse torque values in bone-level implants.

Screw loosening is one of the most common mechanical complications within the prosthetic components of dental implants. Clinicians must know if reverse torque values (RTVs) are affected by contamination of the implant abutment screw hole with either blood, saliva or chlorhexidine. Forty implants were divided into 4 groups (n = 10). Implants were embedded in epoxy resin and placed in a digital torque meter. Screw holes of 30 implants were contaminated with either chlorhexidine (CG), fresh human saliva (SG), or blood (BG), and the remaining noncontaminated screws served as a control group (NC). Abutment screws were tightened using a hand-held torque meter (25 N·cm). Thermocycling (1500 cycles) was performed, and abutment detorque values were calculated using the digital torque meter. RTVs were lower than insertion torque values for all groups. According to Tukey HSD Test, blood contamination of abutment screws resulted in significantly lower RTVs (18.950 ± 2.641 N·cm) when compared with controls. Blood contamination of abutment screw holes was shown to significantly decrease RTVs. Blood contamination may result in greater loosening of implant screws in clinical practice.

An analysis of the biofilms adhered to framework alloys using in vitro denture plaque models.

The purpose of this study was to perform a quantitative and qualitative evaluation of the biofilms formed on framework alloys in vitro. The biofilms formed by unfiltered fresh human saliva or Streptococcus mutans and/or Candida albicans on commercially pure titanium and gold-copper-platinum demonstrated higher amounts than other alloy and resin samples. In contrast, the silverpalladium-copper-gold showed a significantly decreased level of biofilm formation. Although the adhesion level of Streptococcus mutans on cobalt-chromium was high, that of Candida albicans was less extensive. A T-RFLP analysis and qualitative PCR of the microbes in the biofilms were performed. In a cluster analysis of all T-RFLP profiles, the cobalt-chromium pattern was integrated into one cluster. On qualitative PCR, the existence of microorganisms related to caries, preriodontitis and aspiration pneumonia was observed. Our results showed that the biofilm formation on each framework alloy was different in terms of both the quantity and quality.

Coronal microleakage of endodontically treated teeth with intracanal post exposed to fresh human saliva

ObjectiveThe aim of this study was to investigate the coronal microleakage of endodontically treated teeth prepared to receive an intracanal post and teeth with an intracanal post but without a prosthetic crown and exposed to contamination by fresh human saliva.Material and MethodsA mechanical-chemical preparation following the step-back technique was carried out in 35 extracted single-rooted human teeth. The teeth were randomly divided into five groups: G1=root canals instrumented, obturated, and prepared to receive an intracanal post (N=10); G2=root canals with cemented posts but without coronal sealing (N=10); PC1=positive control root canals instrumented and open (N=5); PC2=positive control 2 root canals without instrumentation and open (N=5); and NC=negative control healthy teeth (N=5). The crowns were removed except for the control group of intact teeth. The root canals were obturated and sterilized with cobalt 60 gamma irradiation and were then adapted in an apparatus using a Brain Heart Infusion (BHI) medium and fresh human saliva for contamination. Microbial growth was indicated by the presence of turbidity in the BHI liquid medium.ResultsData were submitted to the Kaplan-Meier Survival Analysis and the Holm-Sidak statistic method, which observed an index of 90% of microleakage in root canals after 24 hours for G1 and 70% of microleakage in samples at the end of 40 days for G2.ConclusionThe results show that root canals with an intracanal post but without a prosthetic crown can be recontaminated when exposed to fresh human saliva in a short period.

Microleakage and penetration of a hydrophilic sealant and a conventional resin‐based sealant as a function of preparation techniques: a laboratory study

Optimal pit and fissure sealing is determined by surface preparation techniques and choice of materials. This study aimed (i) to compare the microleakage and penetration depth of a hydrophilic sealant and a conventional resin-based sealant using one of the following preparation techniques: acid etching (AE) only, a diamond bur + AE, and Er:YAG laser combined with AE, and (ii) to evaluate the microleakage and penetration depth of the hydrophilic pit and fissure sealant on different surface conditions. Eighty recently extracted 3rd molars were randomly assigned to eight groups of ten teeth according to the material, preparation technique, and surface condition. For saliva contamination, 0.1 mL of fresh whole human saliva was used. All samples were submitted to 1000 thermal cycles and immersed in 2% methylene blue dye for 4 h. Sections were examined by a light microscope and analysed using image analysis software (Sigmascan(®)). The combination of Er:YAG + AE + conventional sealant showed the least microleakage. The sealing ability of the hydrophilic sealant was influenced by the surface condition. Er:YAG ablation significantly decreased the microleakage at the tooth-sealant interface compared to the non-invasive technique. The hydrophilic sealant applied on different surface conditions showed comparable result to the conventional resin-based sealant.

Bond strength of a pit-and-fissure sealant associated to etch-and-rinse and self-etching adhesive systems to saliva-contaminated enamel: individual vs. simultaneous light curing

This study evaluated in vitro the shear bond strength (SBS) of a resin-based pit-and-fissure sealant [Fluroshield (F), Dentsply/Caulk] associated with either an etch-and-rinse [Adper Single Bond 2 (SB), 3M/ESPE] or a self-etching adhesive system [Clearfil S3 Bond (S3), Kuraray Co., Ltd.] to saliva-contaminated enamel, comparing two curing protocols: individual light curing of the adhesive system and the sealant or simultaneous curing of both materials. Mesial and distal enamel surfaces from 45 sound third molars were randomly assigned to 6 groups (n=15), according to the bonding technique: I - F was applied to 37% phosphoric acid etched enamel. The other groups were contaminated with fresh human saliva (0.01 mL; 10 s) after acid etching: II - SB and F were light cured separately; III - SB and F were light cured together; IV - S3 and F were light cured separately; V - S3 and F were light cured simultaneously; VI - F was applied to saliva-contaminated, acid-etched enamel without an intermediate bonding agent layer. SBS was tested to failure in a universal testing machine at 0.5 mm/min. Data were analyzed by one-way ANOVA and Fisher's test (alpha=0.05).The debonded specimens were examined with a stereomicroscope to assess the failure modes. Three representative specimens from each group were observed under scanning electron microscopy for a qualitative analysis. Mean SBS in MPa were: I-12.28 (+/-4.29); II-8.57 (+/-3.19); III-7.97 (+/-2.16); IV-12.56 (+/-3.11); V-11.45 (+/-3.77); and VI-7.47 (+/-1.99). In conclusion, individual or simultaneous curing of the intermediate bonding agent layer and the resin sealant did not seem to affect bond strength to saliva-contaminated enamel. S3/F presented significantly higher SBS than the that of the groups treated with SB etch-and-rinse adhesive system and similar SBS to that of the control group, in which the sealant was applied under ideal dry, noncontaminated conditions.