Dentin Surfaces Research Articles

Microbiota of complete removable dentures

Purpose: to study the quantitative and qualitative composition of microflora on the surface of complete removable dentures after 1 and 4 years of use. Materials and methods: 40 patients were diagnosed with complete edentulism (K08.1) using complete removable acrylic dentures for no more than 4 years were examined. The composition of the microflora was determined by mass spectrometry method. Statistical processing of the results of the study was carried out using the computer package Statistica13. To assess the differences between the groups, parametric t-criteria with Bonferroni correction were used for multiple comparisons, the critical level of statistical significance of p was 0.05. Results: it was found that in 4 years the number of yeast and fungi increased by 91%, n=20 (100%); the number of actinobacteria increased by 61%, n=20 (100%); the number of gram-negative bacteria increased by 500% n=20 (100%); the number of anaerobic microorganisms increased by 50% n=20 (100%); the number of cocci and bacilli increased by 190% n=20 (100%). Conclusion: after conducting the research, we found that after 4 years of using removable dentures n=20 (100%), the number of cocci and bacilli increased from 56±5 (105 cells/gram) (p=0.03) to 107±8 (105 cells/gram) (p=0.04). The number of anaerobes increased n=20 (100%) from 68±6 (105 cells/gram) (p=0.0002) to 102±9 (105 cells/gram) (p=0.0002). The number of actinobacteria n=20 (100%) increased from 30±3 (105 cells/gram) to 143±12 (105 cells/gram) (p=0.003). The number of gram-negative bacteria n=20 (100%) increased from 4±1 (105 cells/gram) (p=0.0005) to 24±2 (105 cells/gram) (p=0.0006). The number of fungi and yeast n=20 (100%) increased from 977±90 (105 cells/gram) (p=0.0003) to 1587±136 (105 cells/gram) (p=0.003).

Correlation of Parental and Child Dental Plaque Levels: A Clinical Study

Objective: This clinical study aimed to explore the correlation between dental plaque levels in parents and their children. Specifically, the study examined differences in plaque correlation between mother–child and father–child pairs and evaluated the role of parental education in influencing children’s oral hygiene practices. Materials and Methods: A total of 196 subjects were recruited, comprising 49 mother–child and 49 father–child pairs, with children aged 6 to 15 years. Dental plaque was assessed using the O’Leary Plaque Control Record, applying a liquid plaque discloser and explorer. The plaque index was calculated as the percentage of dental surfaces with visible plaque relative to the total surfaces examined. Results: The findings revealed a significant positive correlation between the parental plaque index (IP_PARENTS) and the children’s plaque index (IP_CHILD) (p < 0.001), indicating a strong relationship. While the father’s plaque index (ID_PARENTS(FATHER)) showed a marginally positive effect on IP_CHILD (p = 0.0589), the interaction between father identification and IP_PARENTS had a significant negative impact (p = 0.0344), suggesting that paternal influence on children’s plaque levels may vary. The model accounted for 28% of the variability in IP_CHILD (pseudo R2 = 0.2758). Conclusions: The analysis demonstrated a significant association between parental and child plaque levels, with minor differences observed between maternal and paternal influence. No significant effects were found for the age or gender of the children. Overall, increased plaque levels in parents were associated with higher plaque levels in their children, with slight variations depending on the parent’s role.

Effect of surface treatments and bonding type on elemental composition and bond strength of dentin

The objective of this study was to explore the effect of different surface treatments and bonding types on elemental composition and bond strength of dentin. Under water cooling, 1.5 mm of tooth structure containing just dentin was cut from 39 extracted human molars. Dentin surfaces were untreated (control) or treated by erbium: yttrium aluminum garnet or femtosecond laser (n = 13, each). One sample from each group underwent scanning electron microscopy. Then, dentin surfaces were bonded by Clearfil SE Bond or Clearfil SE Protect (n = 6, each). Energy dispersive X-ray spectroscopy was performed both after surface treatment and bonding application. The dual-polymerized resin cement was applied to dentin surfaces with a special teflon mold (diameter:3 mm × height:3 mm). After polymerization of the resin cement, shear force was applied at the resin cement-dentin interface. Elemental composition value (weight%) of dentin after surface treatment was analyzed by one-way analysis of variance (ANOVA), and the difference value in pre and post-bonding elemental composition by two-way ANOVA. Paired t-tests were executed to compare the weight% values of each element before and after each bonding application. Bond strength was analyzed by two-way ANOVA. The post-hoc test was Tukey’s honest significant difference test. Both laser treatments increased the mineral content of dentin, compared to the controls (P<0.05). Application of bonding agents decreased the mineral content of dentin compared to the surface treated dentin. Bond strength was unaffected by either surface treatment or bonding type (P>0.05). For resin cementation, either surface treatment is suitable. After laser treatment, Clearfil SE Bond is recommended over Clearfil SE Protect.

Infiltration of salivary proteins into dentin during erosive processes

ObjectiveUltrastructural analyses showed that during erosion under oral cavity conditions, dentin is infiltrated by a substrate morphologically similar to salivary proteins. This in-situ study aimed to investigate the presence of salivary proteins in demineralized dentin. MethodsBovine dentin specimens were attached to individual maxillary splints (n = 1 per subject and condition) and worn intraorally by four subjects for 1 min. During intraoral exposure, the subjects rinsed with 10 ml of either sterile water or 1% citric acid. Additional specimens were eroded in-vitro as controls (n = 2). The specimens were then fixed, embedded in acrylic resin, and ultrathin sections were prepared. The salivary protein lysozyme was labelled with immunogold staining and examined using transmission electron microscopy. ResultsLysozyme was absent in the in-vitro controls but was detected on the dentin surface after rinsing with water, indicating its role in the initial pellicle formation on dentin. After rinsing with citric acid, lysozyme infiltrated deeper layers of the dentin. ConclusionsThese findings support the initial morphological observations that lysozyme, representing other salivary proteins, is deposited in demineralized dentin during erosion with citric acid. Clinical significanceInfiltration of salivary proteins into dentin during erosive processes can be a factor to consider in remineralization approaches under oral cavity conditions.

Maintenance of dental bleaching: A systematic review

After bleaching procedure, color pigments can adhere to the rough dental surface and can trigger more discoloration. In this sense, no standard post-bleaching maintenance technique exists. The purpose of this study was to evaluate the maintenance of enamel color after bleaching procedure through a systematic review. The research question was defined as follows: Is the tooth whitening maintenance necessary after a bleaching treatment? Two reviewers conducted the literature search in PubMed (MEDLINE), Web of Science, Scopus, EMBASE, and SciELO. Both in vitro and clinical trials reporting the color change of bleached enamel after the use of a tooth whitening agent were included in the review. The risk of bias in the included manuscripts was evaluated using the RoBDEMAT tool. A total of 11 articles were included in the qualitative analysis. Due to the lack of groups for comparison, a meta-analysis could not be conducted. The whitening maintenance procedures identified were remineralizing agents, antioxidants, over-the-counter agents, toothpaste containing Blue Covarine, casein phosphopeptide-amorphous calcium phosphate fluoride paste, 0.05% sodium fluoride mouthwash, arginine, nano-hydroxyapatite, nano-carbonate apatite, and CO2 laser. In conclusion, tooth whitening maintenance could be achieved by using some agents. The association of these agents might be beneficial for maintaining the color of the enamel throughout 12 months following bleaching procedure.

Accuracy of repaired maxillary dentures from two different repairing techniques: In vitro study

BackgroundDenture fracture is a common problem with acrylic dentures. The fractured denture can be repaired using various techniques such as self-cure acrylic resin acrylic resin and fiber-reinforced acrylic resin. PurposeThe purpose of this study was to compare the accuracy of dentures repaired with self-cure acrylic resin and fiber-reinforced acrylic resin processed using two different techniques (long-cure and microwave processing). Materials and methodsA total of 20 maxillary complete dentures were processed with two techniques; heat (long cycle) processing (10 dentures) and microwave processing (10 dentures). The maxillary cast and denture surface were scanned with Medit intraoral (Medit i700, Medit, South Korea) and STL files were created. Then, the dentures were sectioned at the midline and repaired using self-cure acrylic resin and fiber-reinforced acrylic resin and scanned with Medit intraoral. Finally, adaptation deviations were analyzed from computer software (Geomagic Control X, 3D Systems Inc., USA). The adaptation deviations in each group (long cure and microwave) were compared using an Independent T-test. Two-way ANOVA was done to see whether curing techniques and repairing methods affect the accuracy of repair. A P-value of 0.05 was considered significant. ResultsThe adaptation deviation was slightly higher in the fiber-reinforced acrylic resin group (0.565 ± 0.093) than in the self-cure acrylic resin group (0.536 ± 0.066). However, there was no statistical difference in the adaptation deviations of repaired dentures with self-cure acrylic resin and fiber-reinforced acrylic resin in the long-curing (P-value 0.245) and the microwave (P-value 0.638). Similarly, the adaptation deviation was slightly higher in the long-curing group (0.577 ± 0.075) than in the microwave group (0.524 ± 0.079). However, there was a statistically significant difference in the adaptation deviation of repaired dentures between long-curing and microwave techniques with self-cure acrylic resin (P-value 0.016) but no difference in fiber-reinforced acrylic resin (P-value 0.127). The result of Two-way ANOVA shows that there is no statistically significant interaction between curing techniques (long curing and microwave) and repairing methods (self-cure acrylic resin and fiber-reinforced acrylic resin) for adaptation deviations (P-value 0.646). However, the curing techniques show statistically significant differences (P-value 0.039). ConclusionAcrylic dentures can be repaired with self-cure resin or fiber-reinforced self-cure resin using various processing methods. The accuracy of the denture after repair is unaffected by the repairing method (self-cure acrylic resin and fiber-reinforced acrylic resin) but the accuracy of the denture after repair is affected by the curing techniques (long-curing and microwave). In self-cure resin, the microwave processing showed higher adaptation deviation and less accuracy, whereas the long-curing processing showed lower adaptation deviation and high accuracy.

In vitro study of the treatment of dentin hypersensitivity with gallic acid combined with sodium fluoride

BackgroundDentin hypersensitivity (DH) is a common oral condition that is associated with severe dental pain. Pain relief is a key focus of the treatment of DH. The purpose of this study was to evaluate the blocking and antacid effects of gallic acid (GA) combined with sodium fluoride (NaF) on dentinal tubules in vitro.MethodsNinety dentin discs from human third molars were treated with 6% citric acid for 2 min. Then, the surface morphologies of ten dentin discs were observed by scanning electron microscopy (SEM). The remaining samples were randomly divided into four groups: the NaF group, which was treated with 1000 ppm NaF; the GA group, which was treated with 4000 ppm GA; the GA + NaF group, which was treated with 1000 ppm NaF + 4000 ppm GA; and the blank group, which was treated with deionized water. The dentin permeability of each sample was measured with a water-filled system before processing and after 7 days of treatment. Dentin morphology and surface deposits were observed by SEM. Then, samples from the NaF, GA + NaF and blank groups were subjected to an acid challenge by incubation with 0.02% citric acid for 2 min. SEM and a water-filled system were used to evaluate the blocking and antacid effects of NaF and GA + NaF.Results1. NaF and GA + NaF significantly decreased dentin permeability. The effect of the GA + NaF treatment was more significant. After acid challenge, both groups still exhibited decreased dentin permeability compared with the initial assessment. 2. Compared with the NaF group, the GA + NaF group had more mineral deposits on the dentin surface and dentin tubules. After acid challenge, the deposits in the GA + NaF group were still clearly visible.ConclusionThe combined effect of GA and NaF on reducing dentin permeability by blocking open dentin tubules is better than that of NaF alone. After acid challenge, the GA + NaF treatment still had a better effect.

Research on in-vivo electron paramagnetic resonance spectrum classification and radiation dose prediction based on machine learning

The in-vivo electron paramagnetic resonance (EPR) method can be used for on-site, rapid, and non-invasive detection of radiation dose to casualties after nuclear and radiation emergencies. For in-vivo EPR spectrum analysis, manual labeling of peaks and calculation of signal intensity are often used, which have problems such as large workload and interference by subjective factors. In this study, a method for automatic classification and identification of in-vivo EPR spectra was established using support vector machine (SVM) technology, which can in-batch and automatically identify and screen out invalid spectra due to vibration and dental surface water interference during in-vivo EPR measurements. In this study, a spectrum analysis method based on genetic algorithm optimization neural network (GA-BPNN) was established, which can automatically identify the radiation-induced signals in in-vivo EPR spectra and predict the radiation doses received by the injured. The experimental results showed that the SVM and GA-BPNN spectrum processing methods established in this study could effectively accomplish the automatic spectra classification and radiation dose prediction, and could meet the needs of dose assessment in nuclear emergency. This study explored the application of machine learning methods in EPR spectrum processing, improved the intelligence level of EPR spectrum processing, and would help to enhance the efficiency of mass EPR spectra processing.

Evaluation of bacterial anti-adhesion and sustained antimicrobial abilities of chlorhexidine gluconate-loaded phase-transited lysozyme nanoparticle suspension on dentine: An exvivo study.

To evaluate the effect of chlorhexidine gluconate-loaded phase-transited lysozyme (CHG@PTL) coating on inhibiting bacterial adhesion and biofilm formation in an exvivo root canal dentine model. The physicochemical and structural characteristics of CHG@PTL nanoparticle suspension and its coating formed on the dentine surface were analysed by thioflavin T fluorescence assay, transmission electron microscopy and confocal laser scanning microscopy (CLSM). The sustained chlorhexidine release profile of the CHG@PTL coating on the dentine surface was compared with that of the 2% CHG solution. By comparing with phosphate-buffered saline, 1% sodium hypochlorite and 2% CHG solutions, the sustained antibacterial ability of the CHG@PTL coating and its effects on adhesion and biofilm formation of three types of bacteria (E. faecalis, S. mutans, and A. viscous) were analysed in exvivo root canal dentine models using the serial plate transfer test (SPTT) and CLSM with live/dead bacterial staining, respectively. CHG promoted the lysozyme protein to form a higher proportion of β-sheet structure during phase transition. In the CHG@PTL nanoparticle suspension, characteristic drug-loaded nanospheres with a high concentration of CHG molecules inside and an outer PTL nanofilm were observed, and they formed a thinner and tighter coating on the dentine surface. The CHG@PTL coating on the dentine surface showed a significantly higher cumulative release amount of chlorhexidine than that of 2% CHG (p < .05). The results of SPTT showed that the CHG@PTL coating had a longer antibacterial duration than the control groups. After 12 h of incubation, a higher number of bacteria were agglutinated on the CHG@PTL coating surface compared to the control groups (p < .05). After 7 days of incubation, the number of agglutinated bacteria significantly decreased. At two time points, the percentage of dead bacteria on the CHG@PTL coating surface was the highest among all experimental groups based on CLSM observation (over 99.9% for all three bacteria, p < .001). CHG@PTL nanoparticle suspension could form an antimicrobial coating on the surface of dentine with a novel 'agglutinating bacteria and sterilizing' mode.

The effect of attachment systems and denture cleaning methods on microbial biomass and composition in implant-supported overdentures: an experimental study

ObjectiveThis research endeavors to scrutinize the influence of attachment systems and denture cleaning methodologies on microbial biomass and composition within the realm of implant-supported overdentures, a crucial consideration for patients with dentition defects necessitating such prosthetic solutions.Subjects and methodsEmploying five polymethyl methacrylate specimens designed to emulate the fitting surfaces of traditional dentures and implant-supported overdentures. Following the polishing of each specimen and the quantification of its roughness, co-cultivation with three distinct microbial strains ensued, culminating in ultrasonic cleaning in water. The bar-clip group, differentiated by the depth of attachment, underwent cleaning employing four diverse methods. Biomass quantities were meticulously recorded both pre and post cleaning interventions, with subsequent data analysis via t-testing and one-way ANOVA, maintaining a significance level of α = 0.05.ResultsThe bar-clip groups demonstrated an elevated degree of microbial adhesion, with the deeper locator group exhibiting heightened biomass residue post-cleaning, indicative of increased cleaning complexity. Ultrasonic cleaning predominantly targeted biofilm and deceased bacteria, whereas chemical cleaners primarily reduced the quantity of viable bacteria. The synergistic application of ultrasonics and chemical cleaning treatments yielded the minimal biomass residue.ConclusionIn contemplating the utilization of dentures milled by dental computer-aided design/manufacturing systems, meticulous pre-use surface polishing is imperative. The extent of biofilm adhesion correlates with the chosen attachment system. This study advocates for the incorporation of ultrasonic cleaning in conjunction with chemical cleaning solutions to optimize the removal of biofilm and live cellular entities in the context of implant-supported overdentures.

Influence of nanohydroxyapatite mouthwash on the growth of Candida albicans biofilm on milled denture surfaces: An in vitro study.

There is a need for effective solutions for the persistent prevalence of denture stomatitis (DS) in denture-wearing populations. This study assessed the impact of nanohydroxyapatite (nanoHAP) nanoparticles on Candida albicans biofilm formation on milled polymethylmethacrylate (PMMA) denture bases. Acquired salivary pellicle was formed on disks milled from a prepolymerized PMMA puck. The disks were assigned to two groups, A (n=18) and B (n=18), and each group was further subdivided into three subgroups (6/subgroup), each treated with either Polident solution (antibacterial denture cleanser), nanoHAP mouthwash, or distilled water. Disks in group A subgroups were soaked in their respective treatment solutions for 8h, followed by biofilm formation on thedisk for 24h. Disks in group B subgroups had C. albicans biofilm formed on them for 24h, followed by soaking in their respective treatment solutions for 8h. Biofilm thickness, biomass, and live/dead cell ratio were determined using aconfocal laser scanning microscope. Biofilm morphology was examined with ascanning electron microscope (SEM). Data were analyzed by ANOVA and Tukey-Kramer multiple comparisons (α=0.05). In group A, nanoHAP mouthwash displayed significant anti-adhesive properties. In group B, biofilm biomass and thickness significantly decreased (p<0.05), with the nanoHAP showing the most substantial reduction in existing biofilm compared to other solutions, but it did not significantly affect cell viability. This study demonstrated the efficacy of nanoHAP mouthwash in inhibiting C. albicans biofilm formation when used as a storage medium for acrylic dentures. It suggests its potential clinical application for preventing denture stomatitis in patients.

Evaluation of Shear Bond Strength of Universal Adhesives to Dentin: in Vitro Study

Aim: Universal adhesives are widely used in restorative dentistry. The aim of this study was to evaluate the shear bond strength (SBS) of universal adhesives to dentin in different application modes. Materials and Methods: The study utilized seven universal adhesives and one total-etch adhesive. The sixty-four extracted intact human molars used in the study were embedded in acrylic blocks to the enamel-cement junction. The occlusal surface was removed to expose the dentin surface. After applying self-etch and total-etch adhesives to the dentin, flowable composite (Clearfil Majesty Flow, Kuraray) was placed in a transparent mold (2.38 mm diameter and 2 mm height) and polymerized. After thermal aging (1000 cycles), a SBS test has been carried out on a universal testing machine. The fracture types formed on the surface of the teeth were examined under a microscope. Data were analyzed by two-way analysis of variance (ANOVA) test (p&lt;0.05). Results: SBS values of universal adhesives on dentin showed statistically significant differences according to adhesive and application mode (p&lt;0.05). Total-etch application produced statistically higher SBS than self-etch application (p&lt;0.05). The two-step universal adhesive (G2 Bond Universal) had the highest SBS in both the self-etch and total-etch application modes (p&lt;0.05). When the bond surfaces of the universal adhesives were examined, fractures occurred most frequently in the adhesive type. Conclusion: The use of universal adhesives in the total-etch mode results in greater bond strength to dentin tissue. Universal adhesive type influences bond strength.

The impact of a-tomatine on shear bonding strength in different dentin types and on cariogenic microorganisms: an in vitro and in silico study

IntroductionThe objective of this study is to investigate the shear bonding strength of a glycoalkaloid, also a novel matrix metalloproteinase enzyme known as α-tomatine, on two different surfaces of dentin (sound & caries-affected) and its efficacy against cariogenic microorganisms using in vitro and in silico methods.MethodsThe effect of a-tomatine at different concentrations (0.75 / 1 / 1.5 µM) on shear bonding strength in caries-affected and sound dentin was also investigated (n = 10; each per subgroup). The analysis of shear bonding and failure tests was conducted after a 24-hour storage period. Fracture surfaces were examined under a scanning electron microscope. A stock solution 3 mM of a-tomatine was prepared for antimicrobial evaluation. Antimicrobial activities of the agents against Streptococcus mutans ATCC 25175, Lactobacillus casei ATCC 4646, and Candida albicans ATCC 10231 standard strains were investigated by microdilution method. In addition, through the method of molecular docking and dynamic analysis, the affinity of a-tomatine for certain enzymes of these microorganisms was examined.ResultsThe pretreatment agent and dentin type significantly influenced shear bonding strength values (p < 0.05). As the molarity of a-tomatine increased, the bonding value decreased in sound dentin, while the opposite was true in caries-affected dentin. According to molecular docking and dynamic analysis, the highest affinity was observed in L. casei’s signaling protein. Microdilution assays revealed a-tomatine to exhibit fungicidal activity against C. albicans and bacteriostatic effects against S. mutans. No antimicrobial effect was observed on L. casei.Conclusiona-tomatine demonstrates a positive impact by serving as both a pretreatment agent for bonding strength and an inhibitor against certain cariogenic microorganisms.

The investigation of endodontic irrigants and polyhexanide-based solution action on smear layer

AIM. The effect of irrigants on the smear layer on the intracanalicular dentin surface is one of the important issues in endodontics. The objective of this article is to determine the effect of different concentrations of polyhexanide-based solutions and standard irrigants on the smear layer using scanning electron microscopy (SEM).MATERIALS AND METHODS. The present study was conducted on 42 extracted teeth (third molars, first and second premolars) with formed apices that had been extracted for orthodontic indications. The teeth were decoronated and samples were prepared. In order to create a smear layer, the lumen of the canals was instrumented with H-file #40 throughout. A simulation of root canal irrigation was conducted by immersing the specimens in a 5-ml container filled with the proper solution for 1 hour: group 1 – no treatment (n = 6); group 2 – saline (n = 6); group 3 – 2% chlorhexidine (n = 6); group 4 – 3% sodium hypochlorite (n = 6); group 5 – 17% EDTA; group 6 – polyhexanide 0.1% (n = 6); group 7 – polyhexanide 0.2% (n = 6). A ~30 nm thick platinum film was sputtered onto the surface of each sample using a magnetron deposition technique. SEM microphotos were acquired on a Vega3 TESCAN scanning electron microscope (SEM) with an SE secondary electron detector, which enables imaging with high topographic contrast. The initial detector (incamera) was employed for image acquisition, with an electron energy of 30 keV. Images were acquired at magnifications of x20 (overview image), x150, x250, x500, x1000, x2500, x7500 for each sample.RESULTS. The samples from groups 1 and 5 demonstrated the absence of a smear layer on the dentin surface and the absence of smear plugs in the dentinal tubules. Groups 2 and 3 are distinguished by the deposition of a pronounced amorphous smear layer and the obturation of all dentinal tubules. Groups 4, 6, and 7 are distinguished by the deposition of a smaller volume of smear layer on the dentin surface, as well as the presence of semi-open or completely open entrances to the dentinal tubules.CONCLUSION. The data obtained indicates that antiseptic compositions based on polyhexanide in concentrations of 0.1 and 0.2% do not have a pronounced effect on the smear layer. However, in visual evaluation of SEM micrographs, their effect is comparable to that of 3% sodium hypochlorite. In instances where enhanced dissolution of the smear layer and smear plugs from the tubules is necessary to facilitate decontamination of the wall dentin, the combination of antiseptics with chelate compounds, such as 17% EDTA, may be employed.

Intaglio surface of CNC milled versus 3D printed maxillary complete denture bases – An in vitro investigation of the accuracy of seven systems

ObjectivesThe accuracy of the intaglio surface of maxillary complete dentures produced with a variety of digital manufacturing systems have been comprehensively investigated, however, not for multiple systems in the same study. This in vitro study endeavors to measure and compare the accuracy of the intaglio surface of maxillary complete denture bases constructed with different photopolymerization-based 3D printing and CNC milling systems. Materials and MethodsTwo subtractive manufacturing machines and five additive manufacturing machines were used to manufacture a maxillary denture bases (n = 10) for analysis. The samples were stored in artificial saliva at 37 °C for 7 days to mimic intraoral use before they were air dried for 5 min, and then scanned with an E3 dental laboratory scanner to generate STL files. A 3D metrology software program was used to analyze the data against the original CAD design. Statistical differences were determined with 1-way analysis of variance (ANOVA) and the Kruskal Wallis test (α=0.05). Color deviation heat maps were used to interpret areas of clinical significance. ResultsThe results indicated that the subtractive manufacturing method delivers the truest and most precise intaglio surface of maxillary complete denture bases. The additive manufacturing technique delivers less true and less precise results with inconsistency observed between the different systems as opposed to the subtractive manufacturing groups which showed no significant differences. ConclusionsWhen manufacturing a complete maxillary denture base subtractive manufacturing will deliver the most consistent and true results.

Effect of propolis added to single-bottle adhesives on water permeation through the hybrid layer.

Water treeing and water droplets are observed within adhesive layers and on the hybridized surface after bonding sound dentin using single-bottle etch-and-rinse adhesives, indicating permeability of the hybrid layer to water. The aim of this study was to assess the efficacy of dentin sealing by adhesives containing propolis by quantifying the area of water transudation from dentinal tubules after dentin hybridization. Brazilian red propolis was added to experimental adhesive and Single Bond (3M/ESPE) adhesive; experimental adhesive and Single Bond without propolis were used as controls. Under simulated pulp pressure, two layers of adhesive were applied to etched human dentin discs. Three minutes after light-curing, the hybridized dentin surface was replicated, and epoxy resin replicas were created to obtain scanning electron microscope images. Data were evaluated using ANOVA and Tukey's test. Single Bond containing propolis significantly decreased water permeation through the hybrid layer compared with the control group. Three minutes after polymerization, the experimental adhesive without propolis had formed a permeable hybrid layer. The addition of Brazilian red propolis significantly reduced surface water on hybridized dentin in a concentration-dependent manner. Two-step etch-and-rinse adhesives containing propolis were effective in reducing water permeation through the hybridized dentin surface.

Effect of mechanical and chemical surface treatments on the repairing of milled and 3D-printed denture bases.

Ensuring a strong bond between chairside autopolymerized acrylic resin to denture base is essential for denture repair and reline procedures. However, there is no established protocol to enhance bond strength between autopolymerizing resin and computer-aided design and computer-aided manufacturing (CAD-CAM) denture base materials. The purpose of this study was to determine shear bond strength of CAD-CAM denture bases and autopolymerizing acrylic resin after mechanical and chemical surface treatments compared with heat-polymerized acrylic resin. Heat-polymerized, milled, and 3-dimensional (3D) printed denture bases were divided into 4 surface treatment protocols: none (control), airborne-particle abrasion (APA), tetrahydrofuran, and Vitacoll application. Autopolymerizing acrylic resin cylinders were bonded to denture surface. Shear bond strength and failure modes were determined after thermocycling. Denture base surfaces were assessed for surface roughness, surface morphology, and microhardness before and after surface treatment. Data was analyzed using two-way ANOVA and multiple comparison tests. The results showed that APA significantly increased shear bond strength and surface roughness of all denture base materials. Tetrahydrofuran and Vitacoll application improved shear bond strength of heat-polymerized acrylic resin, but did not reach the level achieved by APA. Conversely, tetrahydrofuran application improved bond strength of 3D-printed denture to the level of APA. Tetrahydrofuran and Vitacoll application significantly reduced denture base hardness, compared with control and APA. In conclusion, mechanical surface treatment using APA enhances the adhesion of autopolymerizing acrylic resin to heat-polymerized and CAD-CAM denture bases. Tetrahydrofuran and Vitacoll chemical surface treatment improved adhesion to heat-polymerized acrylic resin, with only tetrahydrofuran enhancing bond strength of 3D-printed denture to the level of APA. Without surface treatment, the highest bond strength was shown in 3D-printed denture base material.

Preventing dentin erosion with silver diamine fluoride and salivary pellicle: an in vitro study

ObjectivesTo investigate the preventive and discoloring effects of a single and two weekly applications of 38% silver diamine fluoride (SDF) against dentin erosion.Materials and methods180 dentin blocks were divided into four groups. Group 1 (SDF2) received two weekly applications of 38% SDF. Group 2 (SDF1) received a single application of 38% SDF. Group 3 (SNF) received a daily application of stannous chloride/amine fluoride/sodium fluoride (standard of care for dental erosion). Group 4 (DW) received a daily application of deionized water. The treated blocks were subjected to a 14-day erosive challenge. Crystal characteristics, elemental composition, surface morphology, percentage of surface microhardness loss (%SMHL), surface loss, and color change (ΔE) were investigated using X-ray diffraction (XRD), energy-dispersive spectrometry (EDS), scanning electron microscopy (SEM), hardness testing, profilometry, and digital spectrophotometry, respectively.ResultsXRD and EDS showed dentin surfaces had silver compounds in SDF2 and SDF1, and stannous chloride in SNF. SEM revealed less dentin demineralization with tubular occlusion in SDF2, SDF1, and SNF, but severe demineralization in DW. The %SMHL of SDF2, SDF1, SNF, and DW were 10.8 ± 2.1, 15.7 ± 2.1, 17.9 ± 2.1, and 28.7 ± 2.0 (SDF2 < SDF1 < SNF < DW, p < 0.05). Surface loss (µm) of SDF2, SDF1, SNF, and DW were 5.0 ± 0.6, 6.0 ± 0.6, 6.0 ± 0.7, and 9.0 ± 0.5 (SDF2 < SDF1 = SNF < DW, p < 0.001). ΔE of SDF2, SDF1, SNF, and DW were 26.0 ± 3.4, 12.1 ± 3.8, 6.9 ± 3.5, and 3.9 ± 3.6 (SDF2 > SDF1 > SNF = DW, p < 0.001).Conclusion38% SDF with two weekly applications provided better preventive effects against dentin erosion, but it might discolor dentin.Clinical relevanceThe increased 38% SDF application showed a better anti-erosive potential against dentin erosion. However, SDF caused black staining on the dentin.

Application of the Raman fluorescence method to study the effects of chemical, physical and radiation factors on the mineralization of hard dental tissues

Objective. To study the effect of physical, chemical and radiation factors on the degree of mineralization of the hard dental tissues surface using spectroscopy. Materials and methods. The degree of mineralization of hard dental tissues was studied by the Raman spectroscopy using hardware-software complex InSpectrum M on the teeth removed according to clinical indications (in vitro): in varying degrees of moisture (dry and wet); before and after exposure to acid and remineralizing drug; before and after exposure to radiation Results. The data obtained demonstrated the difference in the indicators in dry (1801 [1800; 1802]) relative units, and moistened (591.5 [591; 592]) teeth. The mineralization of teeth according to Raman Intensity before exposure to citric acid, was (602 [601; 602]) rel. units, and after the exposure it was (152 [152; 153]) rel. units, after application of the cm-2 plate it was (423 [422; 423]) rel. units. The identified differences are reliable (p 0.001). Thus, it is confirmed that organic acids (citric acid) contribute to the enamel demineralization by more than two times, and the use of calcium-containing plates contributes to remineralization almost to the initial state. At the same time, there were no significant differences in the level of mineralization (according to the Raman method of fluorescence spectroscopy) in teeth before and after direct radiation exposure, regardless of dose (2 Gy, 70 Gy, 110 Gy) in any of the functional groups (incisors, canines, premolars, molars). Conclusions. 1. Raman-fluorescence spectroscopy has a high sensitivity and is capable of detecting mineralization, de- and re-mineralization of hard dental tissues. 2. It is recommended to determine the hard tooth tissues mineralization by Raman-fluorescence spectroscopy in a moistened rather than a dry form. 3. Organic acids contribute to the demineralization of enamel, and the use of calcium-containing plates promotes its remineralization. 4. Direct radiation exposure does not have a direct effect on the mineralization of the surface of the hard dental tissues. regardless of the dose applied in all functional groups (incisors, canines, premolars, molars), in all areas of the teeth (equator, cutting edge, gum border).

Comparative evaluation of wettability of AH plus, Ceraseal and Guttaflow bioseal root canal sealers on root canal dentin: An in vitro study

Abstract Context: Effective root canal treatment relies on the ability of sealers to wet and penetrate the root canal system, ensuring a tight seal and preventing bacterial leakage. The current study investigates the wetting ability of newer root canal sealers by evaluating their contact angle. Aim: The objective of the present study was to evaluate and compare the wetting behavior of Guttaflow bioseal, Ceraseal, and AH plus root canal sealers. Materials and Methods: Decoronation and apical third resections of thirty extracted singlerooted human mandibular premolars were done. The roots were then split longitudinally into two halves buccolingually. The root dentin surfaces were treated using 10 mL 3% sodium hypochlorite for 5 min, 10 mL of 17% ethylenediaminetetraacetic acid for 5 min, and 2% chlorhexidine for 10 min. Then, these sixty dentin bars were randomly divided into three groups (n = 20): Group 1 – AH Plus, Group 2 – Ceraseal, and Group 3 – Guttaflow bioseal. The controlled volume of 0.1 mL sealer has been dispensed onto the dentin specimen using a micropipette. The contact angle of a drop of sealer was measured after 5 min using Ossila goniometer. Statistical Analysis Used: The data were analyzed using one-way analysis of variance and Tukey post hoc tests. The statistical significance was at P &lt; 0.05. Results: The mean contact angle values for AH Plus sealer were lower when compared to the other two sealer groups which is statistically highly significant. Conclusions: AH Plus showed lesser contact angle thereby better wettability than Ceraseal and Guttaflow bioseal on the root canal dentin surface.