Acrylic Denture Research Articles

Analysis of reasons for visit in completely edentulous patients requiring repeat prosthetic rehabilitation

Background: Complete laminar dentures are currently the most common prosthetic rehabilitation approach in completely edentulous patients. However, acrylic resin, the primary structural material used in these dentures, has certain well-known disadvantages. Identifying the primary reasons for visit in patients requiring replacement of acrylic complete laminar dentures will help determine the best course of action for improving this type of prosthetic rehabilitation. Aim: To assess the reasons for visit in patients requiring replacement of complete laminar dentures. Materials and methods: Between 2021 and 2022, a comprehensive dental examination was performed in completely edentulous patients who had previously used complete laminar dentures and needed to replace them. The primary factors determining the need for replacement dentures of this type were identified, and their frequency during specific time periods was assessed. The risk of functional defects, mechanical failures, and poor esthetic condition was calculated. Nonparametric analysis (chi-squared test) was used to assess statistical differences between the parameters. The frequency of a specific reason for visit was assessed using relative risk (RR) with a 95% confidence interval (CI). Results: Mechanical failure was the main reason for visit (63.3%) in completely edentulous patients requiring replacement of complete laminar dentures within three years after the dentures were manufactured. After three years of wearing these dentures, the risk of mechanical failure and functional defects significantly increases by 1.8 times (RR=1.4; 95% CI: 0.9–1.9) and 1.6 times (RR=1.6; 95% CI: 1.1–2.6), respectively (p 0.05), with approximately equal frequency (47.8% and 43.7%, respectively). When wearing these dentures for more than six years, visits due to functional defects become the most common (58.3%). Conclusion: The service life of complete laminar dentures is directly associated with the reasons for visit for their replacement. The increased risk of functional defects, such as impaired fixation and stabilization, necessitates developing a set of measures for the prevention of maxillary ridge and mandibular alveolar bone atrophy, as well as dystrophic changes of the mucosa in the denture-supporting area.

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).

Effect of Denture Cleansers on Surface Roughness and Flexural Strength of High Impact Strength Acrylic Denture Base Materials: An In VitroStudy

Effect of Denture Cleansers on Surface Roughness and Flexural Strength of High Impact Strength Acrylic Denture Base Materials: An In VitroStudy

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.

Prosthetic stomatitis: treatment and prevention

Relevance. Traumatic prosthodontic stomatitis is the most frequent in clinical prosthetic dentistry, increasing the effectiveness of prevention and treatment of which is considered an urgent problem of practical dentistry. Objective. To study the effectiveness of using various domestic means for oral care in patients suffering from traumatic prosthetic stomatitis. Materials and methods. The study involved 42 elderly patients suffering from denture stomatitis due to the use of removable acrylic dentures. The patients were divided into 2 groups. In the control group after dentures correction they were recommended to use rinses and irrigations of the oral cavity with antiseptic solutions for a week, and later with infusions of medicinal herbs. Patients of the main group during their follow-up used local anti-inflammatory and wound-healing agents produced by thedomestic industry, as well as those improving the fixation of removable dentures. The effectiveness of denture stomatitis treatment and prevention of recurrence was evaluated on the basis of the patient’s complaints and clinical condition of the oral mucosa. Results. . It was established that for effective therapy of denture stomatitis it is necessary to use specially produced anti-inflammatory agents for the oral cavity during the period of acute inflammatory changes in the mucous membrane of the denture bed, and when using removable acrylic dentures it is necessary to recommend ASEPTA denture fixation cream, which has proved itself not only in the aspect of optimization of microbiota and mucosal immunity of the mouth, but also for optimization of psychophysiological state of patients. Their use makes it possible to achieve 81.47% efficacy of prosthetic stomatitis treatment on the 5th day and 100% efficacy of therapy on the 7th day from the beginning of their use by the patient, as well as in the nearest period to provide prevention of this disease recurrence. Conclusion. For secondary prophylaxis of traumatic prosthetic stomatitis, which occurs most often among the complications when patients use removable acrylic dentures, it is advisable to use specially produced by the domestic industry means possessing anti-inflammatory and wound-healing properties, as well as favorably acting on the mucous membrane of the prosthetic bed.

Benzyldimethyldodecyl Ammonium Chloride-Doped Denture-Based Resin: Impact on Strength, Surface Properties, Antifungal Activities, and In Silico Molecular Docking Analysis.

Candida albicans (C. albicans) adhering to denture-based resins (DBRs) is a known cause of denture stomatitis. A new approach to prevent denture stomatitis is to include antimicrobial substances within DBRs. Here, we examined the mechanical performance and antifungal properties of DBRs containing benzyldimethyldodecyl ammonium chloride (C12BDMA-Cl) as an antimicrobial compound. C12BDMA-Cl is a quaternary ammonium compound, and its antifungal properties have never been investigated when combined with dental acrylic resin. Therefore, we modified a commercially available heat-polymerized acrylic DBR to contain 3 and 5 wt.% of C12BDMA-Cl. Unmodified DBR was used as a control group. Specimens were prepared using the conventional heat processing method. The specimen's flexural strength, elastic modulus, microhardness, and surface roughness were evaluated. C. albicans biofilm was grown on the specimens and assessed via colony-forming units (CFUs) and scanning electron microscopy (SEM). In silico molecular docking was applied to predict the potential C12BDMA-Cl inhibition activity as an antifungal drug. The 3% C12BDMA-Cl DBR demonstrated antifungal activities without a deterioration effect on the mechanical performance. SEM images indicated fewer colonies in DBR containing C12BDMA-Cl, which can be a potential approach to managing denture stomatitis. In conclusion, C12BDMA-Cl is a promising antifungal agent for preventing and treating denture stomatitis.

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.

Denture microbiome shift and changes of salivary inflammatory markers following insertion of 3D printed removable partial PMMA denture: a pilot study

BackgroundThe aim of this study was to investigate the microbiome shift of denture biofilm formation, the incidence of Candida and changes of salivary inflammatory markers following insertion of 3-dimensional printed PMMA denture.MethodsThis was a pilot study of 6 patients provided with 3D printed (test group) or conventionally heat-cured (control group) removable partial acrylic dentures followed up for 6 weeks. 3 denture swabs were collected at week 1, 3 and 6; and saliva samples were collected at baseline, week 1, 3 and 6 following denture insertion. Microbial DNA was isolated, and the 16S rRNA gene was amplified and sequenced to assess the denture microbiota. The presence of Candida was determined using PCR assay. The levels of salivary biomarkers lactoferrin (LTF) and histatin (HTN) were determined using ELISA.ResultsDenture microbiome of both groups exhibited similar microbial compositions at weeks 1, 3 and 6. However, the percentage of Streptococcus in the test group was significantly lower at week 1 (p < 0.05). Greater bacterial diversity was detected in the test group (p < 0.05; pairwise Wilcoxon) after 6 weeks. The presence of Candida was only detected in one sample of the 3D printed denture (test group) after 6 weeks. The level of LTF biomarkers increased in both groups after 6 weeks, however, the level of HTN increased only in the control group.ConclusionsDenture microbiome of both groups demonstrated similar microbial compositions. After 6 weeks, 3D printed denture demonstrated higher diversity with delayed microbiome shift compared to conventional heat cure dentures. 3D printed denture may be a viable alternative to conventional denture and it has a potential to delay microbial dysbiosis.Clinical RelevanceAmong wearers, 3D printed denture can potentially reduce the risk of denture stomatitis. A greater diversity may delay or slow the transition of denture microbiome to dysbiosis.

Options for replacing a single lost anterior tooth in a dentition with reduced periodontal health

To restore comfort, function, and esthetics while maintaining occlusal stability, restoring a single missing anterior tooth in a periodontally impaired dentition is a significant task. An implant-supported crown, traditional three-unit fixed partial denture (FPD), cantilever FPD, resin-bonded FPD, or removable partial denture can be considered in a normal, healthy dentition; however, problems with mobility and poor periodontal support of the remaining dentition may make these procedures unfeasible options as it might be difficult to avoid overloading of the implant in periodontal compromised adjacent teeth, difficult to achieve proper esthetics with conventional FPD, to maintain the stability of dental arch with acrylic resin removable partial dentures is not possible and incidences of frequent debonding of resin bonded FPD are high when abutments are mobiles. Fiber-reinforced composite resin FPD is often effective in these clinical situations to provide a conservative therapy option to restore the patient’s ease and esthetics by limiting mobility.

Evaluating the Effect of Nano-Cellulose Fibers Addition on Impact Strength, Transverse Strength and Surface Hardness of Heat-Cured Acrylic Resin Denture Base Material

Evaluating the Effect of Nano-Cellulose Fibers Addition on Impact Strength, Transverse Strength and Surface Hardness of Heat-Cured Acrylic Resin Denture Base Material

Evaluation of wear resistance and bond strength between different teeth materials and Acrylic Denture base materials (Comparative in vitro study )

Evaluation of wear resistance and bond strength between different teeth materials and Acrylic Denture base materials (Comparative in vitro study )

Effect of different laser modes on acrylic denture repair

Effect of different laser modes on acrylic denture repair

POLYAMIDE FLEXIBLE DENTURES – A BETTER OR WORSE STRATEGY

Background: Polyamide dentures have added advantages over the acrylic dentures in terms of esthetics, comfort and versatility to adapt to the undercut areas. However, the effect of flexibility of these dentures from the view of residual ridge resorption has always been obscure. The aim of this study is to compare the type of denture base with the distribution of masticatory forces by examining the changes on the alveolar mucosa in the histological picture before and after insertion of two widely used dentures. Materials and methods: A total of 20 participants were included in the study, among which 10 patients were allocated for acrylic removable partial dentures and 10 patients were allocated for polyamide flexible removable partial dentures. The patients were asked to rinse their mouth and cement spatula was used to collect the epithelial mucous cells noninvasively by scraping the crest of the residual alveolar ridge with light pressure in premolar-molar area both before insertion and 2 weeks after insertion of the removable partial dentures. The said swab was then smeared on a clean glass slide and fixed in 95% ethyl alcohol and was stained by Papanicolaou (PAP) stain. The PAP-stained smear was analyzed for the presence of keratinized cells and the number of keratinocytes was counted for both acrylic and polyamide denture groups. Results: The results show that both types of denture bases altered the alveolar mucosal keratinization but there was a significant difference in number of keratinized cells between all the three groups. Polyamide flexible partial dentures showed more ortho-keratinized epithelium, which favours better occlusal load distribution. Conclusion: The results concluded that there was decreased masticatory load on the residual alveolar ridge under polyamide denture group due to the flexibility of the denture base material compared to that of the acrylic denture group.

Antimicrobial, Optical, and Mechanical Properties of Saliva-Contaminated Silver–Zeolite Nanoparticle-Incorporated Dental Acrylic Resins

Background and Purpose: This study aimed to evaluate the flexural strength, color change and antimicrobial effect of silver–zeolite nanoparticles (NPs) in acrylic resin materials. Methods: Fifty-six disc-shaped acrylic resin samples were divided into four groups (n = 7) according to concentrations of silver–zeolite NPs (0%, 2%, 4%, 5%). Discs were contaminated with C. albicans and S. mutans. The antimicrobial effect was tested by inoculating contaminated discs on Tryptic soy agar (TSA), Sabouraud Dextrose Agar (SDA), Tryptic soy broth (TSB), and Sabouraud dextrose broth (SDB). Forty rectangular 65 × 10 × 2.5 mm acrylic resin specimens were also classified into four groups (n = 10) according to concentrations of silver–zeolite NPs. For the color change, L, a, and b values of rectangular specimens were examined with a spectrophotometer. A three-point bending test was also performed using a Devotrans device to determine the flexural bond strength of rectangular specimens. Scanning electron microscope analysis (SEM/EDX analysis) was also performed. Results: In this study, the antimicrobial effect increased with the concentration of silver–zeolite NPs added to acrylic resin discs. In our study, adding 2% silver–zeolite NPs was more effective against C. albicans. The antimicrobial effect against S. mutans increased with concentration of silver–zeolite NPs (&lt;0.001). The colonization of C. albicans was significantly reduced by silver–zeolite NPs. A significant increase was observed in the color change as the nanoparticle percentage ratio increased (p &lt; 0.001). The flexural strength values of the groups containing 2% and 4% nanoparticles were found to be clinically acceptable. Conclusions: The study showed that bacterial and fungal colonization is significantly reduced by adding silver–zeolite nanoparticles to acrylic resin discs. Based on its antimicrobial, physical, and mechanical properties, we recommend adding 2% silver–zeolite nanoparticles to the acrylic resin material for optimal results.

Reduction of Multispecies Biofilms on an Acrylic Denture Base Model by Antimicrobial Photodynamic Therapy Mediated by Natural Photosensitizers.

The aim of this study is to investigate the antimicrobial efficacy of antimicrobial photodynamic therapy (PDT) using natural photosensitizers (curcumin, riboflavin, and phycocyanin) and light-emitting diode (LED) irradiation against multispecies biofilms in an acrylic denture base model. Forty-five acrylic specimens were fabricated using heat-curing acrylic resin. The specimens were then infected with a mixed culture of bacterial and fungal species (including Streptococcus mutans, Streptococcus sanguinis, Candida albicans, and Candida glabrata) for 4 days. The acrylic discs were divided into nine groups, with each group containing five discs: control, 0.2% chlorhexidine, 5.25% sodium hypochlorite, curcumin, riboflavin, phycocyanin alone or along with LED. After treatment, the number of colony-forming units (CFUs) per milliliter was counted. In addition, the extent of biofilm degradation was assessed using the crystal violet staining method and scanning electron microscopy. All experimental groups exhibited a significant reduction in colony numbers for both bacterial and fungal species compared to the control (p < 0.001). The PDT groups exhibited a statistically significant reduction in colony counts for both bacteria and fungi compared to the photosensitizer-only groups. The results of this in vitro study show that PDT with natural photosensitizers and LED devices can effectively reduce the viability and eradicate the biofilm of microorganisms responsible for causing denture infections.

Evaluating the physical properties of microwave-cured and heat-cured acrylic denture base materials after the addition of ZrO2 nanoparticles.

Background: The structural, physical, and mechanical properties of denture-based acrylic resin are still compromised by water sorption, water solubility, and porosity. These issues have long called for improved techniques, and the use of nanoparticles is one of them. The main objective of the current investigation was to evaluate and contrast some physical parameters (water sorption, water solubility, and porosity) after the incorporation of ZrO2 nanoparticles (0%, 3% and 5%) into heat-cured acrylic denture base materials (Ivoclare, Major) and microwave-cured acrylic (Acron MC). Materials and methods: A total of 60 resin specimens were manufactured, including 5 specimens for each concentration of ZrO2 NP (30 for porosity and 30 for water sorption and solubility). Followed the manufacturer's directions for preparing the sample of each material. Results: The results were analysed with descriptive statistics, Analysis of Variance(ANOVA) test, Duncan multiple range test, and independent T test demonstrated that the addition of nanoparticles (3% and 5%) decreased water sorption, water solubility, and porosity of PMMA(polymethyl methacrylate) for both types(microwave-cured and heat-cured acrylic denture base materials). Where, at 3%, the ZrO2 nanoparticles showed the best values for all tests compared to the control group. Conclusions: ZrO2 (3% and 5%) nanoparticle reinforcement of acrylic resin can be a useful tactic for lowering water sorption, solubility and porosity, thereby enhancing the performance of the material in various applications for microwave-cured and heat-cured acrylic denture base materials.

Evaluation of the Bond Strength between the Acrylic Teeth and Reinforced or Non-reinforced Complete Denture Base.

The aim of this study was to examine whether the method of surface treatment of the acrylic teeth and reinforcement of the denture base (carbon fibers) affect the reduction of stress concentration for gap initiation at the interface of acrylic teeth and denture base as a measure of bond strength. Samples of cross-sections of acrylic teeth and denture base were isolated from four pairs of complete acrylic dentures (with and without reinforcement of the denture base) and were subsequently subjected to compressive loading in a universal testing machine simulating two different occlusions. Selected groups of acrylic teeth (central incisors, first premolars, and first molars) from complete dentures were treated in various ways (untreated, mechanical, chemical, and mechanical-chemical). The gap size at the interface of acrylic tooth and denture base was measured using a light inverted microscope on selected acrylic teeth of individual quadrants. The one-way analysis of variance was used to investigate the influence of denture base reinforcement and different methods of surface treatment of the acrylic tooth on bond strength at the level of statistical significance of p ≤ 0.001. Microscopic analysis of gap size measured at five selected points at the interface between the acrylic teeth and the base of the complete denture ranged from 40 to 144 micrometers. The one-way analysis of variance showed a statistically significant difference between the arithmetic means of the measured gap sizes concerning different methods of surface treatment of the acrylic teeth. The fracture strength, or load-bearing capacity, of complete dentures reinforced with carbon fibers was increased compared to complete dentures with non-reinforced bases. Reduction in gap size at the interface between the acrylic teeth and the base of complete dentures was influenced by the mechanical-chemical treatment of the lower surface of acrylic teeth, while reinforcement of the complete denture base with carbon fibers had no effect on the bond strength.

The effect of adding ZrO2 nanoparticles on the transverse strength and hardness of microwave-cured acrylic and heat-cured acrylic denture base materials

Background: One drawback of acrylic denture base materials is their liability to fracture, requiring methods to increase fracture resistance. Adding nanoparticles (NPs) represented one of these methods. Purpose: The objectives of this study are to evaluate and compare transverse strength and hardness when adding zirconium oxide nanoparticles (ZrO2 NPs) at concentrations of 0%, 3%, and 5% to heat-cured acrylic denture base materials (Ivoclare, Major) and to microwave-cured acrylic (Acron MC). Methods: Transverse strength was tested with a Universal Testing Machine (GESTER, Fujian, China), while hardness tests were conducted by using a Shore-D hardness durometer (Show, China). The 90 samples were prepared and then divided into three groups for each material. Attenuated total reflectance–Fourier transform infrared (ATR-FTIR) spectroscopy was used to analyze the microstructure. The samples were prepared following the manufacturer’s instructions for each material. Results: The results revealed that the addition of ZrO2 NPs (3%, 5%) improves the transverse strength and hardness of polymethyl methacrylate acrylic resin for both types (microwave-cured and heat-cured acrylic resins). The addition of ZrO2 NPs at 3% concentration shows the highest values for both transverse strength and hardness. The ATR-FTIR confirms no structural chemical changes with the addition of ZrO2 NPs. Conclusion: The study concludes that the incorporation of ZrO2 NPs (3%, 5%) into microwave-cured and heat-cured acrylic resins improves transverse strength and hardness.

Biaxial flexural strength of nanoglass and multiwalled carbon nanotubes reinforced 3D-printed denture base resins and their shear bond strength to 3D-printed and acrylic denture teeth

ObjectiveEvaluation of biaxial flexural strength (BFS) of nanoglass (NG) and multiwalled carbon nanotubes (MWCNTs) reinforced 3D-printed denture base resins and their shear bond strength (SBS) to 3D-printed and acrylic denture teeth. MethodsSilanized NG and MWCNTs were added to 3D-printed denture base resin to obtain four groups: Control, 0.25 wt% NG, 0.25 wt% MWCNTs, and a combination group with 0.25 wt% of both fillers. All specimens were tested before and after 600 cycles of thermal aging. BFS (n = 88) was tested using disk-shaped specimens (12 ×2 mm) centralized on an O ring in a universal testing machine. Weibull analysis was conducted to assess predictability of failure. SBS (n = 176) was tested for acrylic and 3D-printed denture teeth attached to bar-shaped specimens in a universal testing machine followed by failure mode analysis using stereomicroscope. Two and three-way ANOVA tests followed by Tukey post hoc test were conducted for BFS and SBS. Kruskal-Wallis test compared percent change among groups with subsequent Dunn post hoc test with Bonferroni correction (α = 0.05). ResultsBFS was affected significantly by filler content (P < 0.001) and thermal cycling (P < 0.001), with thermal cycling displaying the uppermost effect (Ƞp2 =0.551). A significant interaction between filler content, thermal cycling, and teeth type was displayed by SBS results (P < 0.001, F=10.340, Ƞp2 =0.162). The highest BFS values belonged to 0.25 % MWCNTs while the highest SBS to printed teeth was displayed by the combination. SignificanceThe combination group displayed higher BFS and SBS to printed teeth compared to control which allows 3D-printed materials to have a long-term clinical success.

Oral Colonization by Different Candida Species: First Comparative Study between Denture and Nondenture Wearers in Tunisia.

This study aimed to compare different Candida species present in patients with and without removable dentures to identify alterations in biofilm composition following denture wear within a Tunisian population. A cross-sectional study was conducted, comprising a group of patients wearing removable dentures (test group) and a control group without dentures. In the test group, two mycological samples were obtained: one from the prosthetic intaglio and another from the osteomucosal area bearing the denture. For the control group, mycological samples were collected from the oral mucosa. The collected swabs were cultured on CHROMagar Candida medium, and yeast counts were quantified as colony forming units (CFUs). Candida species were identified through chromogenic analysis. The normality of quantitative variables was evaluated using the Kolmogorov-Smirnov's test. To compare means and ranks between the test and control groups, the independent samples t-test and the Mann-Whitney's U test were employed, respectively. Qualitative variables were compared using Fisher's exact test. Statistical significance was determined at a critical uncertainty value of p < 0.05. A total of 150 participants were involved in this study, with 75 patients in each group. Wearing an acrylic removable denture was found to increase the number of detected Candida species (p < 0.001) and significantly increases the overall growth of Candida spp. (p = 0.001). Specifically, the numbers of CFUs of Candida tropicalis and Candida glabrata were elevated in denture wearers (p < 0.001). Findings stemming from this study indicate that removable dentures promote the growth of Candida species. This can be a predisposing factor for Candida-associated denture stomatitis in cases of poor oral hygiene or compromised immunity. Therefore, it is imperative to emphasize the fabrication of high-quality dentures and the implementation of rigorous postdenture maintenance protocols to prevent or limit Candida infection.