Maxillofacial Silicone Research Articles

The Effect of Zirconium Oxide Nanoparticle on the Tear Strength of Maxillofacial Silicone

Aims: The study aimed to investigate the outcome of different concentrations (0.5%, 1%, 1.5%, 2% by weight ) of zirconium oxide (ZrO2) nanoparticle on tear strength of room temperature vulcanized maxillofacial silicone material. Materials and methods: A total of (50) samples were prepared following the manufacture instruction and divided into five groups (n=10). The group A (control group) without nanoparticle, group B (0.5% ZrO2), group C (1% ZrO2), group D (1.5% ZrO2), group E (2% ZrO2). The tear strength samples were measured by a universal testing machine. Result: there was a highly significant difference between the groups' mean values. The control group (21.91 N/mm) showed non-significant difference with both 0.5% ZrO2 group (22.46 N/mm) and 2% ZrO2 (23.22 N/mm), but a highly significant difference with groups 1% ZrO2 (25.37 N/mm) and 1.5% ZrO2 (27.44 N/mm). Whereas the 0.5% ZrO2 group showed a highly significant difference with both groups (1% and 1.5% ZrO2),but no significant difference with 2% ZrO2 group. 1% ZrO2 group showed a significant difference with 1.5% ZrO2 group and a highly significant difference with 2% ZrO2 group. But group 1.5 % ZrO2 has a highly significant difference with group 2% ZrO2. Conclusion: Incorporation of ZrO2 nanoparticle at 1% and 1.5% by weight enhanced the tear strength of the VST 50F RTV maxillofacial silicone material.

Effect of Adding Different Concentrations of CaCO3-SiO2 Nanoparticles on Tear Strength and Hardness of Maxillofacial Silicone Elastomers

Effect of Adding Different Concentrations of CaCO3-SiO2 Nanoparticles on Tear Strength and Hardness of Maxillofacial Silicone Elastomers

Effect of ultraviolet protective agents on maxillofacial silicone elastomer, part 2: Mechanical properties after artificial aging

Statement of problemThe addition of ultraviolet (UV) protectives may affect the materials’ mechanical properties, which can limit the service life of facial prostheses. PurposeThe purpose of this in vitro study was to investigate the effect of UV protectives on the mechanical properties of maxillofacial silicones after artificial aging. Material and methodsSix color groups (unpigmented, white, yellow, red, blue, and mixed) of addition-type maxillofacial silicone were prepared. Four UV protectives, benzophenone-3 (UV-BP), ethylhexyl methoxycinnamate (UV-EM), titanium dioxide (UV-TD), and ethylhexyl salicylate (UV-ES), at 0.5% and 1% concentrations by weight were incorporated into the silicone before polymerization. The specimens were subjected to accelerated aging in a weathering chamber for 300 and 600 hours and to thermocycling. The tensile strength and percentage elongation, tear strength, and hardness of maxillofacial silicones were evaluated. Data were analyzed by using 4-way ANOVA. The differences were compared by the Tukey honestly significant difference test (α=.05). ResultsTensile strength decreased after 300 and 600 hours of UV aging in 0.5% and 1% UV-BP protective–added groups and increased in thermocycled groups (P<.05). Aging conditions generally showed no effect on the tensile strength of UV-EM, UV-TD, and UV-ES added groups (P>.05). Aging generated a decrease in percentage elongation values compared with nonaged specimens of groups (P<.05). The addition of UV protectives generally did not significantly affect the tear strength of specimens compared with control in the aged groups (P>.05). The hardness of UV protective–added groups increased when compared with that of nonaged groups after 300 and 600 hours of UV aging (P<.05). Also, thermally aged groups showed increased hardness than nonaged groups (P<.05). ConclusionsThe protective UV-BP addition caused decreased tensile strength, percentage elongation, and tear strength in both concentrations. The UV-EM and UV-ES provided increases in tensile strength and percentage elongation of the silicone in the 0.5% concentration. The addition of UV-BP, UV-EM, and UV-ES did not make significant differences; however, UV-TD significantly decreased the hardness values of the silicone.

Effect of ultraviolet protective agents on maxillofacial silicone elastomer, part 1: Color stability after artificial aging

Statement of problemSilicone elastomers have been widely used for rehabilitation of facial defects for more than 50 years. However, color change is the most common problem limiting the service life of facial prostheses. Whether the addition of ultraviolet protectives may enhance color stability of these materials is unclear. PurposeThe purpose of this in vitro study was to investigate the effect of ultraviolet protectives on the color stability of maxillofacial silicones after artificial aging. Material and methodsSix color groups (unpigmented, white, yellow, red, blue, and mixed) of addition-type maxillofacial silicone were prepared. Four ultraviolet protectives benzophenone-3, ethylhexyl methoxycinnamate, titanium dioxide, and ethylhexyl salicylate at 0.5% and 1% concentrations by weight were incorporated into the silicone before polymerization. The specimens were artificially aged in an accelerated weathering chamber for 300 and 600 hours and in a thermocycling device. The color change values (E) of the maxillofacial silicones were evaluated. Data were statistically analyzed by using 4-way ANOVA. The differences were compared by the Tukey honestly significant difference test (α=.05). ResultsBenzophenone-3 and ethylhexyl methoxycinnamate protectives did not reduce the ΔE values, and the 1% titanium dioxide groups exhibited lower ΔE values than the 0.5% titanium dioxide groups. Ethylhexyl salicylate protective generally reduced the ΔE values significantly in all color and aging groups when compared with the control groups (P<.05). In all control and ultraviolet protective groups, the highest ΔE values were seen with the red color in 300 and 600 hours of aging. Generally, no significant difference (P>.05) was seen in the ΔE values, which were clinically acceptable among the thermocycled color groups. After 600 hours of accelerated aging, the ΔE values were found to be higher than the values of 300-hour aging. ConclusionsEthylhexyl salicylate protective incorporated into maxillofacial silicones may improve color stability.

Disinfectant effects of Brazilian green propolis alcohol solutions on the Staphylococcus aureus biofilm of maxillofacial prosthesis polymers

Statement of problemBrazilian green propolis may be an alternative product that reduces the development of a microbial biofilm on the polymers used for maxillofacial prostheses. However, its effects as a disinfectant have not been fully established. PurposeThe purpose of this in vitro study was to investigate the effects of Brazilian green propolis alcohol solutions against the Staphylococcus aureus biofilm on polymers used in maxillofacial prostheses, the maxillofacial silicone elastomer (MDX4-4210), and specific acrylic resins for ocular prostheses. Material and methodsA total of 324 disk-shaped specimens (3×10 mm) of each material were fabricated. All specimens were contaminated with S. aureus (108 cells/mL) to assess the antibiofilm activity of immersion solutions and protocols. Thus, 162 specimens of each material were randomly distributed and equally divided into 5 groups of disinfectants and 1 control group: 3 separate groups of 2.5%, 5%, and 10% propolis alcohol solutions, 1 group of 5% propolis alcohol gel, a positive control group of 2% chlorhexidine gluconate, and a negative control group of distilled water. Specimens (n=9) were disinfected by immersion for 5, 10, and 15 minutes and immersed in culture medium for 24 hours. Any notable turgescence in the final medium was considered indicative of a biofilm. The effects of disinfectants were analyzed by a turbidity assay and by scanning electron microscopy. Data were analyzed descriptively. ResultsThe final medium with specimens disinfected with 10% propolis alcohol solution showed no turbidity, indicating constant efficacy against the S. aureus biofilm. Similarly, these findings were observed in the 2% chlorhexidine gluconate group. Scanning electron microscopy images demonstrated that the surface of the polymers treated with 10% propolis alcohol solution did not show bacterial colonies. ConclusionsDisinfection with 10% green propolis alcohol solution was effective in eliminating the S. aureus biofilm from specimens of maxillofacial elastomer and N1 acrylic resin specific to ocular prostheses by immersion for 5 minutes.

Spectrophotometric Analysis of the Effect of aging on Color change of Maxillofacial Silicone

Purpose: The purpose of this study is to evaluate the change in color stability of maxillofacial silicon after exposing it to natural weathering and disinfection using neutral soap (shampoo). Material and Methods: 60 specimens were prepared from addition linking vinyl polydimethyl siloxane and divided into 3 groups (n=20). The specimens were then conditioned differently as follows, Group I: Dark room storage (control group); Group II: Neutral soap disinfection; Group III: Outdoor natural weathering for 2 months. The color changes of the specimens were measured using a Reflective spectrophotometer (X-Rite, model RM200QC, Neu-Isenburg, Germany) using the Commission Internationale de I’Eclairage (CIE).5 The measurements were taken after 1 month then after two months (follow up period). Results: There was insignificance increase in color change in neutral soap (shampoo) group. There was significance increase in color change in natural weathering group. Also there was significance difference between groups after 1 month and two months. Conclusions: Exposure to outdoor natural weathering and the disinfection with neutral soap (shampoo) causes color alteration of the maxillofacial silicone.

Efficacy of incorporating silver nanoparticles into maxillofacial silicone against Staphylococcus aureus, Candida albicans, and polymicrobial biofilms

Statement of problemThe presence of biofilms on maxillofacial silicone increases the risk of infections and reduces durability. Whether silver nanoparticles (AgNPs) with potent antimicrobial effects help reduce biofilm formation is unclear. PurposeThe purpose of this in vitro study was to assess the antimicrobial effect of sub 10-nm AgNPs in maxillofacial silicone against Staphylococcus aureus, Candida albicans, and mixed species biofilms containing both and to test the effectiveness of different AgNP concentrations against all 3 biofilms in vitro. Material and methodsSilicone disks (M511; Technovent Ltd) containing 0.0% (control), 0.1%, and 0.5% AgNPs were fabricated and treated with S. aureus, C. albicans, and mixed species strains of both in 24-well culture plates containing appropriate media. Each well received a 0.1-mL aliquot of the standardized suspension of microorganisms. The plates were incubated for 21 consecutive days, and colony-forming units per milliliter (CFU/mL) were measured on the first, third, fifth, seventh, fifteenth, and twenty-first day with the Miles and Misra method. Data were analyzed by 2-way ANOVA and the paired t test to evaluate the relationship between AgNP concentration, microbial strain, and time (α=.05). Mean CFU/mL differences for each time and for each biofilm category were assessed by repeated measure ANOVA. ResultsAgNPs decreased the mean CFU/mL in both concentrations compared with the control. The 0.1% concentration showed sustained efficacy throughout the test, while the 0.5% concentration had high efficacy initially with a gradual decrease. However, the results were inconsistent for the mixed biofilm. The paired sample t test at day 3 and 15 and day 3 and 21 showed statistically significantly different results (P<.001) in all but 1 group in the 0.5% concentration. The 2-way mixed ANOVA showed statistically significant (P<.001) interaction between AgNP concentration and time in all groups. The 1-way ANOVA of AgNP concentrations was statistically significantly different (P<.001) for all time points. A statistically significant (P<.001) effect of time on CFU/mL was found for all the AgNP concentration groups in all 3 biofilms. ConclusionsSilicone elastomers with sub 10-nm AgNPs displayed antimicrobial properties in vitro against S. aureus, C. albicans, and mixed species strains. AgNPs (0.1%) were effective against both microbial strains and can provide a baseline for further long-term studies regarding antimicrobial efficacy, silver ion leaching, and cellular internalization. Mixed species biofilm needs further exploration with standardized study parameters.

Color Stability and Mechanical Properties of Two Commonly Used Silicone Elastomers with e-Skin and Reality Coloring Systems.

To evaluate the color stability and mechanical properties of two commonly used maxillofacial silicone elastomers after addition of pigments and opacifiers and before and after artificial aging. This study evaluated two maxillofacial silicone elastomers: A-2000 and M511. Two different pigment and opacifier systems (e-Skin and Reality Series) were used with the elastomers. Control groups (no pigment or opacifier) and experimental groups (each with subgroups containing additional pigments and/ or opacifiers) were fabricated for each of the silicone elastomers. A total of 51 specimens were evaluated for color stability, and 100 for mechanical properties. A spectrophotometer was used to assess CIE L*a*b* values before and after aging. CIELAB 50:50% perceptibility threshold (ΔE* = 1.1) and acceptability threshold (ΔE* = 3.0) were used to interpret color changes. A durometer and universal testing machine were used to evaluate the mechanical properties. ANOVA and Fisher least significant difference (LSD) test were performed to determine the statistical significance of the results (P < .05). Significant differences in color measurements (ΔE*) were found for all silicone groups following artificial aging (P < .05). ΔE* values for the mixed pigment/opacifier subgroups of both elastomers were below the perceptibility threshold. Additionally, after aging, the hardness, tear strength, and tensile strength significantly increased for all silicone groups (P < .05), while percent elongation significantly decreased (P < .05). Artificial aging affected the color stability and mechanical properties of the pigmented silicone elastomers with added opacifier. Overall, A-2000 with e-Skin group displayed the most color stability, with its mechanical properties being the least affected by artificial aging.

An evaluation of a technique to improve the mechanical properties of maxillofacial silicone elastomers with zinc oxide nanoparticles

Statement of problemSilicone elastomer is the most used material for fabricating maxillofacial prostheses, but the material has low tensile and tear strength and insufficient elasticity. Whether the addition of zinc oxide nanoparticles will improve these properties is unclear. PurposeThe purpose of this in vitro study was to evaluate the effect of adding different concentrations of zinc oxide (ZnO) nanoparticles on the clinically critical mechanical properties of a maxillofacial silicone. Material and methodsNano-ZnO was added in concentrations of 1%, 2%, 3%, and 5% by weight to Cosmesil M511 High Temperature Vulcanization (HTV) silicone elastomer. Silicone without nano-ZnO or ethanol served as a conventional group, while silicone without nano-ZnO and with ethanol served as the control group. Tensile strength and elongation tests were done according to International Organization for Standardization (ISO) 37. A tear strength test was done according to ISO 34-1. A Shore A hardness test was done according to ISO 7619. In total 144 specimens were fabricated, with 48 specimens for each test. Field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) tests were used to assess the efficiency of the dispersion method, monitoring the particle size of nano-ZnO. Statistical analysis used 1-way ANOVA and the Tukey post hoc test (α=.05). ResultsFESEM showed a homogenous dispersion of ZnO nanoparticles within the silicone matrix. XRD and FESEM showed a reduction in cluster size of nano-ZnO after sonication. The FTIR-ATR test revealed no significant difference between the conventional and the control group (P>.05). The 3%ZnO demonstrated significantly higher tensile strength, elongation percentage, and tear strength than the control group (P<.05). Shore A hardness showed a significant decrease between the conventional and control group. Hardness increased directly and proportionally to an increase in the concentration of nanofiller. ConclusionsSonication of nano-ZnO in ethanol represented an effective and straightforward way to disperse nano-ZnO in a silicone elastomer matrix. This improved the quality of the nanocomposite without affecting the base material and without the need for a coupling agent or addition of a third material. The overall mechanical properties of the M511 maxillofacial silicone elastomer improved most with a 3%ZnO concentration.

Effect of tropical outdoor weathering on the surface roughness and mechanical properties of maxillofacial silicones

Statement of problemThe climate of tropical Southeast Asia includes high humidity and ultraviolet radiation that reduce the lifespan of silicone prostheses by inducing changes in their mechanical properties and color stability. Studies on the surface roughness (SR) and mechanical properties of different silicone elastomers (SEs) subjected to the natural tropical weather of Southeast Asia are lacking. PurposeThe purpose of this in vitro study was to evaluate the SR, tensile strength (TS), and percentage elongation (% E) of different SEs subjected to outdoor weathering in the Malaysian climate. Material and methodsType-II dumbbell-shaped specimens (N-120) (nonweathered=15, weathered=15) were made from 3 room-temperature vulcanized (A-2000, A-2006, and A-103) and 1 heat-temperature vulcanized (M-511) silicone (Factor II). For 6 months, weathered specimens were subjected to outdoor weathering inside a custom exposure rack. Simultaneously, the nonweathered specimens were kept in a dehumidifier. Subsequently, the SR was measured with a profilometer; TS and % E were measured by using a universal testing machine. Two-way ANOVA was used to compare the means of the tested properties of the nonweathered and weathered specimens, and pairwise comparison was carried out between the silicones (α=.05). ResultsAfter outdoor weathering, the SR, TS, and % E were adversely affected by weathering in the Malaysian environment. Among the silicone materials, A-2000 showed the least TS changes (2.51 MPa), while A-2006 demonstrated significant changes in percentage elongation after outdoor weathering (266.5%). M-511 exhibited the highest mean value (2.50 μm) for SR changes. In addition, A-103 SE showed statistically significant differences in most pairwise comparisons for all 3 dependent variables. ConclusionsBased on the evaluation of mechanical properties, A-103 can be suggested as a suitable silicone for maxillofacial prostheses fabricated for tropical climates. However, A-2000 can be a suitable alternative, although significant changes to surface roughness were detected after outdoor weathering.

An in vitro study to compare the influence of two different primers on the peel bond strength between a maxillofacial silicone material and an acrylic resin material versus a composite resin material.

Aim:The aim of this study was to evaluate and compare the peel bond strength of an autopolymerizing acrylic resin and a fiberreinforced composite (FRC) resin to a heat temperature vulcanizing maxillofacial silicone (M511) using two different primers.Settings and Design:In vitro - comparative study.Materials and Methods:Autopolymerizing acrylic resin and FRC resin specimens with a dimension of 75 mm (length) ×10 mm (width) × 3 mm (height) were fabricated. A total of 60 samples were split into six categories based on the substructure material and primers (A330G primer and Sofreliner tough primer) used to bond the maxillofacial silicone to the FRC and acrylic resin specimens. In a universal testing machine, the peel bond strength was conducted at a 10 mm/min crosshead speed until bonding failure occurred.Statistical Analysis Used:The t-test, one-way analysis of variance, and the Tukey's honest significant difference (post hoc test) tests were used to statistically assess the values.Results:The Sofreliner tough primer produced the greatest peel bond strength in both the acrylic resin (0.89690 N/mm) and the FRC resin groups (3.19860 N/mm). Adhesive failures predominated in the acrylic resin group regardless of the primer used. The FRC group showed predominantly cohesive failures with both the A330G primer and Sofreliner tough primer.Conclusion:This study suggests that FRC resin combined with Sofreliner tough primer can significantly enhance the peel bond strength.

Fungicidal Effect of Lemongrass Essential Oil on Candida albicans Biofilm Pre-established on Maxillofacial Silicone Specimens.

ABSTRACTAims:This in-vitro study aimed to evaluate the efficacy of lemongrass (Cymbopogon citratus) essential oil in eradicating Candida albicans biofilm pre-established on the maxillofacial silicone specimens.Materials and Methods:Two maxillofacial silicones, namely, MDX4-4210 and Multisil Epithetik, were used for the fabrication of 6 mm diameter disks (n = 21 for each brand of silicone). A 48-h mature C. albicans ATCC 10231 biofilm was pre-established on sterile silicone specimen. These disks were then exposed to various concentrations of lemongrass essential oil ranging from 0.31% to 5% (v/v), 20% (v/v) nystatin, and RPMI-1640 medium for 18–20 h. After exposure, the remaining viable fungal biofilm was examined by the XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide]-reduction assay. All data were analyzed by using a regression coefficient and a post hoc Tukey HSD multiple comparisons test (α = 0.05).Results:Different brands of silicone used for fabrication did not significantly affect the formation of mature C. albicans biofilm (P =0.302). A 5% (v/v) lemongrass essential oil significantly eliminated fungal biofilm by approximately 95% (P =0.031). However, less than 50% of the fungal biofilm was eliminated by the tested oil at a concentration as low as 0.31% (v/v). Furthermore, the fungicidal efficacy against C. albicans biofilm of lemongrass essential oil at 2.5% (v/v) was as potent as that of 20% (v/v) nystatin suspension (P = 0.99).Conclusion:Lemongrass essential oil expressed fungicidal effect on C. albicans biofilm pre-established on the disks fabricated from different brands of silicone. Additionally, the fungicidal effectiveness of the oil against the mature fungal biofilm was dose-dependent.

Evaluation of mechanical properties and cytotoxicity of maxillofacial silicone material after incorporation of zirconia nanopowder

Abstract Resilient polymeric materials such as silicone elastomers are currently used for maxillofacial prostheses construction but the strength of these materials and their clinical performance need to be optimized with the addition of reinforcing fillers. This study investigates the effect of zirconia nanopowder addition on tear strength, tensile strength, elongation at break, Shore A hardness, surface roughness and cytotoxicity of VST-50 maxillofacial silicone. Silicone base was mixed with different amounts (1%, 2% and 3%) of zirconia nanopowder using a vacuum mixer. Silicone without filler was used as control for comparison. Scanning Electron Microscopy and Atomic Force Microscopy were utilized to assess the efficiency of high-shear vacuum mixing as filler dispersion method and the surface topography, respectively. Both SEM and AFM images showed that the zirconia nanopowder were distributed fairly well within the polymer. Statistically, highly significant increase in tear strength, tensile strength and hardness with non-significant decrease in elongation at break and non-significant increase in surface roughness were seen with 1% and 2% groups. Whereas with 3% group, there was significant improvement in tear strength, tensile strength and hardness but there was significant undesirable decrease in elongation and increase in roughness. Cytotoxicity test revealed that the addition of zirconia nanopowder was nontoxic to Rat Embryonic Fibroblast (REF) cells and there was non-significant change in the cell viability of all study groups after 24- and 72-hours incubation periods. In conclusion, the addition of 2% by weight nano zirconia to VST-50 maxillofacial silicone could be beneficial in enhancing its performance.

Colour Stability Of Maxillofacial Silicone Materials After Disinfection And Aging Procedures A Systematic Review

Maxillofacial prosthesis should restore the appearance to near normal so that the affected person should have a normal mental status as well as quality of life. The longevity of any kind of maxillofacial silicone prosthesis is determined by its color and mechanical properties. To systematically assess the current published literature on the stability of&nbsp; color of maxillofacial silicone materials after 10 minutes of disinfection and aging, a literature search on PubMed and Google Scholar was

The color stability of maxillofacial silicones: A systematic review and meta analysis.

Aim:This systematic review aims to identify and interpret results of studies that evaluated the changes in the color stability of maxillofacial prosthetic materials due to chemical instability of silicones and pigments and the effect of exposure to environmental conditions and aging factors on the same.Settings and Design:This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines (PRISMA).Materials and Methods:Relevant articles written in English only, before November 15, 2019, were identified using an electronic search in the PubMed/Medline conducted to identify pertinent articles. The relevancy of the articles was verified by screening the title, abstract, and full text, if they met the inclusion criteria. A total of 42 articles satisfied the criteria, from which data were extracted for qualitative synthesis. This review protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO registration number CRD42019124562).Statistical Analysis Used:Since considerable data heterogenicity was present in all studies except the ones on incorporation of TiO2 for which meta-analysis using random effects model was performed.Results:The database search resulted in 234 studies, of which 202 articles were excluded due to lack of relevance, duplication, and unavailability of data. The remaining 32 fulltext articles were assessed for eligibility, out of which 2 articles were excluded. Twelve articles were yielded by manual search. A total of 42 studies were included in the present systematic review. Due to heterogeneous data, meta-analysis could be only carried out with the effect of TiO2 nano particle on color stability.Conclusions:Although there has been extensive amount of research in this field, an ideal maxillofacial silicone exhibiting good color stability in various human and environmental aging conditions is yet to be identified. Human and environmental aging conditions have an adverse effect on the color stability and addition of TiO2 nano particle seems to improve the same.

Effect of Particle Size of Nano-Oxides on Color Stability and Mechanical Properties of Maxillofacial Silicone Elastomers: An In Vitro Study.

To evaluate the physical and mechanical properties of maxillofacial silicone elastomers following the incorporation of a specific particle size and concentration of nano-titanium dioxide (TiO2) and nano-zinc oxide (ZnO). Nano-TiO2 and nano-ZnO of 20-nm and 40-nm particle sizes and in 1% and 2% concentrations were chosen. Silicone elastomer samples were prepared according to the manufacturer's recommendations. The nano-oxides were incorporated via hand spatulation. The samples were subsequently tested for hardness and color stability and were then subjected to aging in an aging chamber for 1,008 hours, following which they were again evaluated for hardness, color stability, and surface roughness. A significant change was noted in the physical and mechanical properties post-aging in all the groups. The samples with nano-TiO2 of 40-nm particle size/2% concentration had the highest hardness, while color stability and surface roughness were higher in samples with nano-TiO2 of 20-nm particle size/1% and 2% concentrations, respectively. It can be concluded that 20-nm nano-TiO2 particles best maintain the ideal properties of maxillofacial silicone elastomers and can potentially be used as alternative opacifiers when mixed with A-2186 maxillofacial silicone elastomers.

Effect of nano-oxides on the color stability of maxillofacial silicone elastomers

Statement of problemA significant challenge of craniofacial prostheses is their limited service life because of degradation and color instability. In spite of improvements in the materials and techniques used for the fabrication of silicone maxillofacial prostheses, undesirable color change over time remains a challenge. Zn and Ti nano-oxides (nano-TiO2) have been reported to impart an ultraviolet- (UV) shielding property to silicone elastomers. However, studies examining the effects of nanopigments on the color stability of craniofacial prostheses are sparse. PurposeThe purpose of this in vitro study was to evaluate the color stability of a room-temperature vulcanizing (RTV) silicone elastomer with the addition of iron oxide and titanium dioxide nanopigments under accelerated artificial aging. Material and methodsSixty disks (Ø15×2 mm) were fabricated from RTV silicone 4408 Q. The specimens were divided into 5 groups containing iron oxide nanopigment, iron oxide nanopigment and rutile nano-TiO2 (as an opacifier), burnt sienna pigment, burnt sienna and nano-TiO2, and silicone without pigment or opacifier. The specimens were subjected to accelerated aging in a Xenotest chamber for 1000 hours. CIELab color coordinates and the total color difference (ΔE∗) values were determined before and after aging. ΔE∗ values were compared between the groups by using 1-way ANOVA and Tamhane multiple comparisons (α=.05), and a standard deviation of 1.09 was considered. ResultsANOVA showed that the values of ΔE∗ differed among all groups (P<.05). The minimum amount of a color change perceived (ΔE∗ approximately =1.1) by the visual system as the threshold was observed in the specimens treated with burnt sienna and nano TiO2. The greatest color change occurred in the specimens treated with iron oxide nanopigment. As per the acceptable clinical threshold, the color change was satisfactory in all groups. ConclusionsNano-TiO2 with burnt sienna groups had a lower color change than the other groups. The color change in all groups was within a clinically acceptable range.

The Influence of Filler Particles on the Mechanical Properties of Maxillofacial Prosthetic Silicone Elastomers: A Systematic Review and Meta-Analysis.

Although numerous studies have demonstrated the benefits of incorporating filler particles into maxillofacial silicone elastomer (MFPSE), a review of the types, concentrations and effectiveness of the particles themselves was lacking. The purpose of this systematic review and meta-analysis was to review the effect of different types of filler particles on the mechanical properties of MFPSE. The properties in question were (1) tensile strength, (2) tear strength, (3) hardness, and (4) elongation at break. The findings of this study can assist operators, technicians and clinicians in making relevant decisions regarding which type of fillers to incorporate based on their needs. The systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A total of 26 original articles from 1970 to 2019 were selected from the databases, based on predefined eligibility criteria by two reviewers. The meta-analyses of nine papers were carried out by extracting data from the systematic review based on scoring criteria and processed using Cochrane Review Manager 5.3. Overall, there were significant differences favoring filler particles when incorporated into MFPSE. Nano fillers (69.23% of all studies) demonstrated superior comparative outcomes for tensile strength (P < 0.0001), tear strength (P < 0.00001), hardness (P < 0.00001) and elongation at break (P < 0.00001) when compared to micro fillers (30.76% of all studies). Micro fillers demonstrated inconsistent outcomes in mechanical properties, and meta-analysis of elongation at break argued against (P < 0.01) their use. Current findings suggest that 1.5% ZrSiO4, 3% SiO2, 1.5% Y2O3, 2–6% TiO2, 2–2.5% ZnO, 2–2.5% CeO2, 0.5% TiSiO4 and 1% Ag-Zn Zeolite can be used to reinforce MFPSE, and help the materials better withstand mechanical degradation.

Effect of plant-extract disinfectant solutions on the specific properties of reinforced maxillofacial silicone elastomers with nanofiller and intrinsic pigment

Abstract Objective This study aimed to evaluate the effects of disinfectant solutions, namely, the alcoholic extract of Salvadora persica L. (A1 = 10% and A2 = 15%) and chlorhexidine digluconate (A3 = 2%), on the tear strength and hardness of room temperature vulcanizing (RTV) VST50F and heat temperature vulcanizing (HTV) Cosmesil M511 silicone elastomers before and after reinforcement with nanofillers (TiO2) and intrinsic pigment. Materials and Methods: A total of 320 specimens were prepared, with 160 specimens each for RTV and HTV silicone. Forty specimens were evaluated before disinfection and divided into two equal groups, namely, control (without additive) and experimental (with additive) groups, for tear strength and hardness tests. The 120 specimens were divided into three equal groups, with two equal subdivisions for tear strength and hardness tests, and were evaluated after disinfection. ANOVA and Tukey's honest significant difference tests were conducted for group comparisons (significance level set at P &lt; 0.05). Results: The tear strength of all groups decreased after disinfection, with the highest values in the experimental group. Most comparisons showed significant differences. A1 exhibited no significant effect on the tear strength and hardness of the HTV control and the hardness of the RTV experimental specimen. The hardness of the HTV control was not significantly affected by A3. A1 with A3 did not significantly affect the tear strength and hardness of the RTV control and the tear strength of the RTV experimental specimen. The results of comparisons between A1 and A2, and A1 and A3 in the HTV tear strength of the experimental group and the A2 and A3 of the control and experimental groups were not significant. Conclusions: S. persica L. can be used as a natural disinfectant agent. The reinforcement of maxillofacial silicone prosthesis can extend its survival duration.

Evaluation the Effect of Nano Yttrium Oxide Addition on the Mechanical Properties of Room Temperature-Vulcanized Maxillofacial Silicone Elastomers

Objective: This study aims to investigate the effects of yttrium oxide (Y2O3) nanopowder inclusion on the mechanical properties, including tear strength, tensile strength, elongation percentage, hardness, and surface roughness, of room temperature-vulcanized maxillofacial silicone elastomers. Materials and Method: Y2O3 nanoparticles (30–45 nm) were added to VST50F platinum silicone elastomers in two weight percentages (1 and 1.5 wt%) as tested by the pilot study that showed superior results. A total of 120 specimens were qualified and divided into the control group and experimental groups (1 and 1.5 wt% Y2O3). Each group was subdivided into four identical subgroups in accordance with intentionally performed tests (tear strength, tensile strength and elongation percentage, shore A hardness, and surface roughness). For each subgroup, 10 specimens were used for each test. Data were statistically analyzed with significance level considered at p &lt; 0.05. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were also conducted. Results and Discussion: SEM showed that NPs were distributed well within the silicon matrix. FTIR spectra proved no chemical reaction occurred between the Y2O3 NPs and VST50F silicone. Tear strength and hardness values significantly increased in the experimental groups compared with the control group. Tensile strength and surface roughness values increased non significantly. Elongation percentage values decreased non significantly. Conclusion: Incorporating Y2O3 NPs into VST50F maxillofacial silicone improved the tear strength with slight increase in tensile strength. Hardness and surface roughness increased but within accepted clinical levels. Elongation percentage slightly decreased.