Effect of phytochemical-filled microcapsules with antifungal activity on material properties and dimensional accuracy of denture base resin for three-dimensional printing

A Novel Approach of Administering Cranberry Extract Into 3D-Printed Denture Bases for the Prevention of Denture-Induced Stomatitis: An Observational Study

BACKGROUND

Complete dentures play an important role in restoring oral function and aesthetics, yet they may contribute to denture stomatitis, necessitating improved materials and hygiene practices. Cranberry extract, known for its antifungal properties, presents a promising avenue for preventing stomatitis when incorporated into novel denture materials.

AIMS AND OBJECTIVES

This research aimed to assess the efficiency of cranberry extract-infused stereolithography (SLA) 3D-printable resins in preventing denture-induced stomatitis and compare their mechanical properties with conventional heat-cured denture base polymers.

MATERIALS AND METHODS

Fifteen patients aged 45 to 60 with completely edentulous maxillary and mandibular arches received two sets of dentures: control dentures made from heat-activated polymethyl methacrylate (PMMA) and treatment dentures made from cranberry-infused 3D-printed resin. Candidal colony-forming units (CFUs) and confocal microscopy were used to assess biofilm formation on 30 samples. For the evaluation of mechanical properties, 30 samples were made in each group, and the flexural strength and fracture toughness were examined for both the control and test groups.

RESULTS

Significantly fewer CFUs were observed in 3D-printed dentures compared to PMMA dentures at 104 concentrations (p=0.03). Biofilm thickness was significantly lower in 3D-printed dentures (p=0.039), but volume fraction biofilm exhibited no discernible change (p>0.05). Surface coverage was significantly reduced in 3D-printed dentures (p=0.028). Flexural strength was higher in 3D-printed samples (124.25±2.67 MPa) compared to PMMA (109.76±9.35 MPa), with a statistically significant difference. Fracture toughness was also significantly higher in 3D-printed dentures (1.60±0.12) compared to PMMA (1.38±0.95) (p=0.028).

CONCLUSION

Cranberry-infused 3D-printable resins demonstrate promise in dropping Candida adhesion and biofilm formation, potentially lowering the risk of denture stomatitis. Moreover, these resins exhibit superior mechanical properties compared to conventional denture base polymers, suggesting a potential alternative for prosthodontic applications.

Assessing the Current Landscape and Future Directions of Digital Denture Technology

Digital dentures are removable dental prostheses fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) technology. This study aimed to explore the trends in digital dentures. A comprehensive four-phase search and selection strategy was framed.

Dimensions and Lens.org databases were used. Boolean operators were used to combine keywords.

The most significant growth occurred by 2021, with 71 publications and 984 citations. Egypt had the highest publication rankings, with 46 total publications (TP) and 45 total citations (TC). The University of Geneva played a significant role in contributing to 16 TP and 491 TC. Egyptian Dental Journal ranked at the top. The group with four authors had an even higher number of authorships, with a total of 60. The top four keywords were CAD/CAM, 3D printing, CAD-CAM, complete denture, and digital dentistry. The Glossary of Prosthodontic Terms, Ninth Edition, was referenced 614 times and had the highest average number of citations (75.2). The top three writers had strong relationships with the three sources and preferred to publish using four keywords. The 11-author group, cluster 6, had the highest level of network cooperation.

In conclusion, research on digital dentures has grown in terms of number of articles and citations.

Silver vanadate nanomaterial incorporated into heat-cured resin and coating in printed resin - Antimicrobial activity in two multi-species biofilms and wettability

OBJECTIVES

To incorporate the nanostructured silver vanadate decorated with silver nanoparticles (AgVO3) into denture base materials: heat-cured (HC) and 3D printed (3DP) resins, at concentrations of 2.5 %, 5 %, and 10 %; and to evaluate the antimicrobial activity in two multi-species biofilm: (1) Candida albicans, Candida glabrata, and Streptococcus mutans, (2) Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus, and the wettability.

METHODS

The AgVO3 was added to the HC powder, and printed samples were coated with 3DP with AgVO3 incorporated. After biofilm formation, the antimicrobial activity was evaluated by colony forming units per milliliter (CFU/mL), metabolic activity, and epifluorescence microscopy. Wettability was assessed by the contact angles with water and artificial saliva.

RESULTS

In biofilm (1), HC-5 % and HC-10 % showed activity against S. mutans, HC-10 % against C. glabrata, and HC-10 % and 3DP-10 % had higher CFU/mL of C. albicans. 3DP-5 % had lower metabolic activity than the 3DP control. In biofilm (2), HC-10 % reduced S. aureus and P. aeruginosa, and HC-5 %, 3DP-2.5 %, and 3DP-5 % reduced S. aureus. 3DP incorporated with AgVO3, HC-5 %, and HC-10 % reduced biofilm (2) metabolic activity. 3DP-5 % and 3DP-10 % increased wettability with water and saliva.

CONCLUSION

HC-10 % was effective against C. glabrata, S. mutans, P. aeruginosa, and S. aureus, and HC-5 % reduced S. mutans and S. aureus. For 3DP, 2.5 % and 5 % reduced S. aureus. The incorporation of AgVO3 into both resins reduced the metabolic activity of biofilms but had no effect on C. albicans. The wettability of the 3DP with water and saliva increased with the addition of AgVO3.

CLINICAL SIGNIFICANCE

The incorporation of silver vanadate into the denture base materials provides antimicrobial efficacy and can prevent the aggravation of oral and systemic diseases. The incorporation of nanomaterials into printed resins is challenging and the coating is an alternative to obtain the inner denture base with antimicrobial effect.

Tendency of microbial adhesion to denture base resins: a systematic review

Objectives

Digital denture fabrication became an alternative method to conventional denture fabrication. However reviewing the antimicrobial performance of newly introduced digital fabrication methods in comparison to the conventional method is neglected. Aim of study: this review was to compare the antiadherence properties of various CAD-CAM subtractive (milled), additive (3D printed) conventional denture base resins. In order to answer the developed PICO question: "Does CAD-CAM milled and 3D printed denture base resins have microbiological antiadherence properties over the conventional ones?" We included comparative studies on digitally fabricated Denture base resins with conventionally fabricated one in term of microbial adhesion.

Methods

All in vitro studies investigated the microbial adherence to CAD-CAM milled and 3D printed denture base resins in comparison to conventional were searched in the PubMed, Web of Sciences, and Scopus databases up to December 2023.

Results

Fifteen studies have been investigated the microbial adhesion to milled and 3D printed denture base resins. CAD-CAM milled resins significantly decreased the microbial adhesion when compared with the conventional resins and 3D printed resins, while the later showed a high tendency for microbial adhesion. The addition of antifungal agents to 3D printed resins significantly reduced C. albicans adhesion. In terms of 3D printing parameters, printing orientation affected adherence while printing technology had no effect on microbial adhesion.

Conclusion

Denture base materials and fabrication methods significantly affect the microbial adhesion. CAD-CAM milled denture base resins demonstrated low microbial adhesion. 3D-printed resins showed high tendency for C. albicans adhesion. The antiadherent properties of 3D-printed resins can be improved by incorporating antifungal agents or changing the printing parameters, but further investigations are required to validate these modifications.

Effect of layer thickness, build angle, and viscosity on the mechanical properties and manufacturing trueness of denture base resin for digital light processing

OBJECTIVES

To investigate effects of layer thickness, build angle, and viscosity on the mechanical properties and trueness of denture base resins used for digital light processing (DLP).

METHODS

Two denture base resins for DLP in different viscosity (high and low) were tested by using two manufacturing parameters:1) layer thickness (LT) (50- or 100-μm) and 2) build angle (BA) (0-, 45-, and 90-degree). disk- and bar-shaped specimens were used to evaluate hardness and flexural strength, respectively. Denture base specimens were used to examine trueness, and the deviation was calculated as the root mean square. Three-way analysis of variance (ANOVA) was conducted to determine the interaction among the three factors (viscosity, LT, and BA). Statistical significance was set at P < .05.

RESULTS

Effects of LT and BA on hardness differed according to viscosity, with significant interactions among three factors (P=.027). Regardless of LT or BA, the low-viscosity group had higher hardness than the high-viscosity group (P<.001). In terms of flexural strength, no significant interaction was detected between the factors (P=.212), however, the effects of LT and BA were significant (P=.003 and P<.001, respectively). Regarding trueness, a significant interaction was observed between viscosity and BA (P=.001). Low-viscosity group had higher trueness than high-viscosity group when the 45- and 90-degree BA were applied (P<.001).

CONCLUSIONS

LT and BA significantly affected the mechanical properties and trueness of the 3DP denture base, depending on the viscosity. For hardness and trueness, using low-viscosity resin and manufacturing with 50-μm LT and 45-degree BA are recommended.

CLINICAL SIGNIFICANCE

Resin viscosity affects the influence of LT and BA on the hardness, flexural strength, and trueness of DLP-generated denture bases. A 50-μm LT and 45-degree BA can be used with a low-viscosity resin to fabricate denture bases with higher hardness and trueness.

Feasibility of microencapsulated phytochemical as disinfectant for inhibition of Candida albicans proliferation on denture base produced by digital light processing

BACKGROUNDS

A proper disinfection of denture is vital to prevent a fungal infection. A study on the feasibility of microencapsulated phytochemical as complementary disinfectant and its interaction with effervescent tablet immersion on denture base resin is lacking.

OBJECTIVES

The aim of this study was to examine the feasibility of phytochemical-filled microcapsules as disinfectant for the inhibition of Candida albicans (C. albicans) attachment on the denture base produced by digital light processing (DLP).

METHODS

54 denture base specimens uniformly mixed with or without 5wt% phytochemical-filled microcapsules were prepared using DLP. Fungal cells were inoculated onto the surfaces of the specimens, which were divided into three different disinfection treatment groups (n = 9): 1) none, 2) sterile tap water immersion for 15 min, and 3) effervescent tablet immersion for 15 min. After each treatment, the biofilm on denture surface was stained with a crystal violet solution to measure the absorbance. The number of fungal colonies was counted as colony-forming units (CFU) per mL. Morphological changes were examined by microscopy. An aligned rank transform analysis of variance was performed to analyze the interaction of presence of microcapsule and disinfection condition, with statistical significance set at P < 0.05.

RESULTS

Both for the absorbance and CFU, there was no significant interaction between the presence of microcapsules and disinfection conditions (P = 0.543 and P = 0.077, respectively). The presence of microcapsules was statistically significant (both P < 0.001), while the effect of disinfection condition was not significant (P = 0.165 and P = 0.189, respectively). Morphological changes in fungi were detected in the groups containing microcapsules, whereas undamaged hyphal structures were found in those without microcapsules, irrespective of disinfection treatments.

CONCLUSIONS

The presence of phytochemical-filled microcapsules significantly reduced the adhesion of C. albicans and inhibited its proliferation on denture surfaces, regardless of disinfection conditions.

Prospects on Tuning Bioactive and Antimicrobial Denture Base Resin Materials: A Narrative Review

Denture base resin (DBR) materials are used in dentistry in constructing removable dentures and implant-supported prostheses. A plethora of evidence has demonstrated that DBR materials are associated with a high risk of denture stomatitis, a clinical complication where the soft oral tissues underneath the resin-based material are inflamed. The prevalence of denture stomatitis among denture wearers is high worldwide. Plaque accumulation and the infiltration of oral microbes into DBRs are among the main risk factors for denture stomatitis. The attachment of fungal species, mainly Candida albicans, to DBRs can irritate the underneath soft tissues, leading to the onset of the disease. As a result, several attempts were achieved to functionalize antimicrobial compounds and particles into DBRs to prevent microbial attachment. This review article explored the advanced approaches in designing bioactive and antimicrobial DBR materials. It was reported that using monomer mixtures, quaternary ammonium compounds (QACs), and organic and inorganic particles can suppress the growth of denture stomatitis-related pathogens. This paper also highlighted the importance of characterizing bioactive DBRs to be mechanically and physically sustainable. Future directions may implement a clinical translational model to attempt these materials inside the oral cavity.

Antifungal activity, mechanical properties, and accuracy of three-dimensionally printed denture base with microencapsulated phytochemicals on varying post-polymerization time

BACKGROUND

Studies on the antifungal activity, flexural strength, Vickers hardness, and intaglio surface trueness of three-dimensionally printed (3DP) denture bases with microencapsulated phytochemicals with respect to changes in post-polymerization time (PPT) are lacking.

METHODS

Specimens of various shapes and dimensions were fabricated with a 3DP denture base resin mixed with 5 wt% phytoncide-filled microcapsules. Each specimen was subjected to different PPT protocols of 5, 10, 20, and 30 min. Specimens without microcapsules with 5-min PPT were used as the negative control group. Cell colonies were counted to evaluate antifungal activity. Three-point bending and Vickers hardness tests were performed to measure the flexural strengths and hardness of the specimens. Fourier-transform infrared spectrometry was used to inspect the degree of conversion (DC). The intaglio surface trueness was measured using root-mean-square estimates calculated by superimposition analysis. A non-parametric Kruskal-Wallis test or one-way analysis of variance was performed (α = 0.05).

RESULTS

The specimens with microcapsules and 10-min PPT showed the highest antifungal activity among the tested groups. Compared with the positive control group (5-min PPT), the specimens with PPTs of 10 min or longer showed significantly higher mean flexural strength, higher DC, greater hardness, and better trueness (all, P < 0.05). Except for the difference in antifungal activity, no statistically significant differences were detected between the specimens subjected to 10-, 20-, and 30-min PPT.

CONCLUSION

The 3DP denture base filled with microencapsulated phytoncide showed different antifungal activity and physical properties on changing PPT. The 3DP denture base containing phytoncide-filled microcapsules at 5 wt% concentration and subjected to 10-min PPT exhibited sufficient antifungal activity as well as mechanical properties and accuracy within clinical acceptance.