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Maxillofacial Prosthetic and Reconstructive Materials

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: 10 August 2024 | Viewed by 10648

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Special Issue Editor

Prof. Dr. Mark W. Beatty

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Guest Editor

1. Department of Veterans Affairs, VA Medical Center, Omaha, NE, USA
2. Department of Adult Restorative Dentistry, University of Nebraska Medical Center, Lincoln, NE, USA
Interests: development of maxillofacial prosthetic material; property characterization of dental restorative materials, hard and soft tissues

Special Issue Information

Dear Colleagues,

Facial disfigurement is the most visible and disabling condition present in the orofacial complex. It diminishes self-image and self-esteem, and produces psychological anguish that leads to depression, isolation and a poor quality of life. Facial disfigurement arises from trauma, burns and surgical removal of tumors. Treatment modalities include reconstructive surgery, implantation of alloplastic or resorbable materials and construction of maxillofacial prostheses. Reconstructive surgical techniques have limitations due to their reliance on autogenous and allogeneic materials. They are in short supply, may not conform to the intricate geometry required to replicate missing tissue and, if used as grafts, contribute to donor site morbidity. Consequently, the need for alternative treatment approaches has spawned research to develop new biomaterials, derived from both synthetic and biological origins.

Facial prosthetic materials are essential to restoring missing structures when surgical and reconstructive strategies are unsuccessful or not possible. Traditional facial prosthetic materials are constructed primarily from copolymers and elastomers that are flexible, stretchable and provide adequate translucency to permit reasonable color matching with surrounding facial skin. Still, the needed improvements are many, including better resistance to tearing, fungal growth inhibition, improved comfort and “skin-like” feel, longer color stability and physical durability, to name a few.

Facial reconstructive biomaterials are intended to replace the form and function of missing tissues. Ideally, these materials exhibit biomimetic qualities, either as stand-alone materials or in combination with cell-based strategies. Although successes have been realized, challenges remain for reliably producing facial tissue replacements that are structurally, functionally and aesthetically competent, offer uncomplicated surgical placement and fully integrate with surrounding biological structures.

Recent advances in science and technology offer new avenues for materials development through incorporation of nanoscience, advanced imaging, additive manufacturing and novel chemistries, to name a few. This presents a new realm of exciting strategies for producing advanced prosthetic and reconstructive materials that are essential to delivering state-of-the-art care.

Compared to other biomaterials, facial materials research receives little attention and is granted little research funding. Consequently, the field is largely under-researched and advancements to date are attributed to a finite number of dedicated scientists and clinicians. This Special Issue of Materials affords the opportunity to document current developments in the field and inspire thought for innovative approaches towards future research that embraces a wide range of scientific expertise.

I am honored to serve as editor of this Special Issue, and I invite you to submit a research article, communication or review paper that addresses this important topic.

Prof. Dr. Mark W. Beatty
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

facial prosthetic materials
maxillofacial prosthetic materials

Published Papers (8 papers)

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Research

Jump to: Review

14 pages, 5567 KiB

Open AccessArticle

Effect of Thixotropic Agent on the Color Stability of Platinum-Based Silicone Maxillofacial Elastomers after Artificial Aging

by Sudarat Kiat-amnuay, Pinar Cevik and Cem Kurtoglu

Materials 2023, 16(17), 5867; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16175867 - 27 Aug 2023

Cited by 1 | Viewed by 719

Abstract

Maxillofacial prostheses are essential for restoring natural appearance and function in individuals with defects in the head and neck regions. Thixotropic agents, as liquid additives, are known to increase the viscosity of silicone elastomers. However, color deterioration remains a challenge in facial prostheses, leading to the need for refabrication. Despite this, there is limited research on the effect of thixotropic agents on the color stability of silicone maxillofacial elastomers. This study aims to investigate the impact of different thixotropic agent amounts on the color degradation of various maxillofacial silicone elastomers. Three elastomers (A-2000, A-2006, and A-2186) were combined with five pigments (no pigment as control, red, yellow, blue, and a mixture of red, yellow, and blue), and mixed with six thixotropic agent quantities (0, 1, 2, 3, 4, and 5 drops). A total of 450 specimens were fabricated (n = 5) and aged in an artificial aging chamber. L*, a*, b* readings were obtained before and after aging using a digital spectrophotometer. Color difference (ΔE*) means and standard deviations for 150 kj/m², 300 kj/m², and 450 kj/m² were calculated. Statistical analyses, including four-way ANOVA and Fisher’s PLSD test, were conducted to determine any significant differences (p < 0.05) among the groups. A comprehensive analysis revealed significant four-way interactions among the groups. In the mixed-pigmentation group, adding 4 drops of thixotropic agent resulted in ΔE* above 3 only in A-2186 silicone at 300 and 450 kj/m² energy levels. However, the color stability of mixed-pigmented A-2000 and A-2006 remained within the acceptable thresholds of 3 ΔE* at all irradiance levels in this study. At each energy level, A-2006 exhibited the highest color stability with an increasing thixotropic agent quantity among all the silicones. Conversely, A-2186 was more affected by the increased number of thixotropic agent drops in each pigmentation group, including the control group at 450 kj/m². The quantity of thixotropic agent plays a crucial role in determining the color stability of different silicone elastomers pigmented with various intrinsic pigments. The thixotropic agent amount has a more significant impact on color stability than the type of pigment used in the silicone elastomers. A key overarching insight from this investigation is the identification of a safety threshold for the thixotropic agent quantity of 3 drops for each silicone type, pigmentation, and energy level. These findings highlight the importance of considering the proper combination of thixotropic agents, pigments, and silicone materials to achieve optimal color stability in maxillofacial prosthetic applications. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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10 pages, 2766 KiB

Open AccessArticle

Coloring Effects of Disinfectants on Pure or Nano-TiO₂-Incorporated Maxillofacial Silicone Prostheses

by Pinar Cevik

Materials 2023, 16(16), 5580; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16165580 - 11 Aug 2023

Cited by 1 | Viewed by 683

Abstract

Silicone elastomers play a crucial role in the field of maxillofacial prosthodontics. To maintain optimal hygiene, various disinfectants have been reported to clean silicone prostheses. Nevertheless, when selecting a disinfectant, it is important to consider not only its antimicrobial efficacy, but also its compatibility with the materials, to minimize any potential impact on the physical properties of the material surfaces. The coloring effect of such disinfectants on different types of silicone is of interest. A total of 144 silicone specimens (72 pure silicones, 72 nano-TiO₂-incorporated silicones, from A-2000 and A-2006 silicones) were fabricated in this study. The spectrophotometric analysis was carried out, and the initial CIE L*a*b* color values were measured prior to disinfection. Specimens in each silicone group (with or without nano-TiO₂) were subjected to a 30-h disinfection period simulating 1 year of disinfection with the following disinfectants: Control (tap water), 0.2% chlorhexidine gluconate, 4% chlorhexidine gluconate, 1% NaOCl, neutral soap, and effervescent. After the second color values were recorded, the color change (∆E*) was calculated. Significant differences were observed among the disinfectants for both the A-2000 and A-2006 silicone groups. Nano-TiO₂ did not show a color protection effect in A-2000 silicone. In contrast, nano-TiO₂ incorporation provided color protection against CHG 0.2%, CHG 4%, and NaOCl in A-2006 silicone. Most of the disinfectants did not show acceptable color stability over time. In pure A-2000 silicone, except for 0.2% chlorhexidine, all disinfectant groups demonstrated a color change within the acceptability threshold of 50:50% (∆E* = 3.0). On the other hand, in nano-TiO₂-incorporated A-2006 silicone, only 0.2% and 4% chlorhexidine demonstrated an acceptable color change. Overall, chlorhexidine could be used as a suitable disinfectant in maxillofacial silicone prostheses. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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13 pages, 1611 KiB

Open AccessArticle

Colour Stability of Two Commercially Available Maxillofacial Prosthetic Elastomers after Outdoor Weathering in Al Jouf Province

by Mahmoud Gamal Salloum, Kiran Kumar Ganji, Ali Mohammed Aldajani and Shital Sonune

Materials 2023, 16(12), 4331; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16124331 - 12 Jun 2023

Cited by 2 | Viewed by 973

Abstract

Facial prostheses are created from special elastomers modified for their specific physical and mechanical properties; however, they also show two common major clinical problems: gradual discolouration of the prosthesis over time in service environment and deterioration of static, dynamic, and physical properties. As a result of external environmental factors, facial prostheses may become discoloured and discolour by changing colour from intrinsic and extrinsic colouring, and this is associated with the intrinsic colour stability of elastomers and colourants. Thus, in this in vitro study, a comparative evaluation of the effect of outdoor weathering on the colour stability of A-103 and A-2000 room-temperature vulcanised silicones used for maxillofacial prosthesis was conducted. To accomplish this study, a total of 80 samples were fabricated, 40 samples of each material were grouped as clear (20) and pigmented (20). These samples were mounted on wooden board and the assembly was placed on the roof of the dental school from October 2021 to March 2022. To maximise the amount of sunlight on the specimens, the exposure rack was set on five 68° angles from horizontal and also to prevent standing water. The specimens were left uncovered during exposure. The testing of samples was conducted with the help of a spectrophotometer. The colour values were recorded in the CIELAB colour system. It describes the three colour coordinates (colour values) x, y, and z in three new reference values of L, a, and b, aiding in numerically classifying colour differences. After 2, 4, and 6 months of weathering, testing was conducted using a spectrophotometer and the colour change (ΔE) was calculated. The A-103 RTV silicone group with pigmentation showed the maximum change in colour after six months of environmental conditioning. The data for colour difference within groups were analysed using a one-way ANOVA test. Tukey’s post hoc test assessed the pairwise mean comparison’s contribution to the overall significant difference. The nonpigmented A-2000 RTV silicone group showed the maximum change in colour after six months of environmental conditioning. After 2, 4, and 6 months of environmental conditioning, pigmented A-2000 RTV silicone showed better colour stability than A-103 RTV silicone. The patients requiring facial prosthesis do need to work on outdoor fields, and thus weathering will have deleterious effects on such prosthesis. Hence, the selection of appropriate silicone material with respect to the Al Jouf province region is crucial, which includes economic, durable, and colour stability. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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17 pages, 1723 KiB

Open AccessArticle

Viscoelastic Properties of Human Facial Skin and Comparisons with Facial Prosthetic Elastomers

by Mark W. Beatty, Alvin G. Wee, David B. Marx, Lauren Ridgway, Bobby Simetich, Thiago Carvalho De Sousa, Kevin Vakilzadian and Joel Schulte

Materials 2023, 16(5), 2023; https://0-doi-org.brum.beds.ac.uk/10.3390/ma16052023 - 28 Feb 2023

Cited by 2 | Viewed by 1633

Abstract

Prosthesis discomfort and a lack of skin-like quality is a source of patient dissatisfaction with facial prostheses. To engineer skin-like replacements, knowledge of the differences between facial skin properties and those for prosthetic materials is essential. This project measured six viscoelastic properties (percent laxity, stiffness, elastic deformation, creep, absorbed energy, and percent elasticity) at six facial locations with a suction device in a human adult population equally stratified for age, sex, and race. The same properties were measured for eight facial prosthetic elastomers currently available for clinical usage. The results showed that the prosthetic materials were 1.8 to 6.4 times higher in stiffness, 2 to 4 times lower in absorbed energy, and 2.75 to 9 times lower in viscous creep than facial skin (p < 0.001). Clustering analyses determined that facial skin properties fell into three groups—those associated with body of ear, cheek, and remaining locations. This provides baseline information for designing future replacements for missing facial tissues. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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12 pages, 2124 KiB

Open AccessArticle

Effect of Nano Ceramic Coating on Color Perceptibility and Acceptability of Polymethylmethacrylate: In Vitro and Clinical Study

by Laura Koo Min Chee, Arghya Kamal Bishal, Harshdeep Singh Bhatia, Alvin G. Wee, Christos Takoudis, Cortino Sukotjo and Judy Chia-Chun Yuan

Materials 2022, 15(24), 8748; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15248748 - 08 Dec 2022

Cited by 1 | Viewed by 1232

Abstract

The effect of a novel nano-ceramic coating (TiO₂) using an atomic layer deposition (ALD) technique on the surface of polymethyl methacrylate (PMMA) material was investigated. The patients’ and clinicians’ perception and acceptance of the PMMA color with TiO₂ coating were also examined. In vitro color measurement was performed on thirty specimens (light, original, and dark pink) before and after TiO₂ coating. Patients’ and clinicians’ perception and acceptance of color changes on PMMA were measured and compared. Descriptive and analytic statistics were analyzed (a = 0.05). TiO₂ films were successfully deposited on the PMMA specimen by the ALD technique. Color changes after TiO₂ coating were observed on all three PMMA shades, significantly higher than the established 50:50% perceptibility threshold, but below the established 50:50% acceptability threshold. The percentage of patients that perceived a color difference after TiO₂ coating were 83.3%, 63.9%, and 77.8% for light, original, and dark pink, respectively. The percentages of clinicians that were satisfied with the color difference were 96.4%, 80%, and 69.2% for light, original, and dark pink, respectively. Color changes after TiO₂ coating were observed, but below the acceptable threshold. The clinical survey demonstrated that a color difference was perceived but was clinically acceptable. In general, laypeople have lower perception and higher acceptance of changes in PMMA color than clinicians. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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24 pages, 8640 KiB

Open AccessArticle

Effect of Superhydrophobic Coating and Nanofiller Loading on Facial Elastomer Physical Properties

by Rahmi Khairani Aulia, Mark W. Beatty and Bobby Simetich

Materials 2022, 15(20), 7343; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15207343 - 20 Oct 2022

Cited by 1 | Viewed by 1152

Abstract

Facial prosthetics are currently constructed of materials that are far from optimal; superior materials with a “skin-like” feel are required. In this study, the property changes brought about by the consecutive additions of hydrophobic- and uncoated nano-SiO₂ to polydimethylsiloxane (PDMS) are assessed, and the alterations are compared with those observed for conventional submicron SiO₂-filled materials. In sequence, 0%, 0.5%, 5%, 10%, and 15% by weight of each filler type were successively added to vinyl-terminated PDMS. Tensile, tear, Durometer hardness, translucency, and viscoelastic properties were assessed, and hardness and translucency were further measured after 3000 h of outdoor weathering. The results showed that 15% coated nano- SiO₂-filled PDMS materials given the highest tensile strength, elastic modulus, storage modulus, loss modulus, tear strength, and durometer hardness (p < 0.05), whereas 15% submicron coated SiO₂-filled materials displayed the highest failure strain and translucency parameter (p < 0.05). Only 10%- and 15%-filled submicron SiO₂ PDMS materials were altered by outdoor weathering; nevertheless, the increases were assessed to be too small to be clinically perceptible. As increased filler levels provided protection against solar radiation, heat, and moisture, only unfilled and 0.5%-filled PDMS formulations discolored from weathering. 15%-filled superhydrophobic-coated nano- SiO₂-filled PDMS was found to produce the strongest, most tear-resistant, and least translucent materials, but it also produced materials with limited stretchability and high hardness, which were regarded to be downsides for creating a “skin-like” feel. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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12 pages, 31622 KiB

Open AccessArticle

Effect of Surface Tooling Techniques of Medical Titanium Implants on Bacterial Biofilm Formation In Vitro

by Sonia Sarfraz, Pilvi-helinä Mäntynen, Marisa Laurila, Juho Suojanen, Juha Saarnio, Sami Rossi, Jani Horelli, Mika Kaakinen, Junnu Leikola and Justus Reunanen

Materials 2022, 15(9), 3228; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15093228 - 29 Apr 2022

Cited by 4 | Viewed by 2077

Abstract

The aim of this study was to assess the biofilm formation of Streptococcus mutans, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli on titanium implants with CAD-CAM tooling techniques. Twenty specimens of titanium were studied: Titanium grade 2 tooled with a Planmeca CAD-CAM milling device (TiGrade 2), Ti₆Al₄V grade 5 as it comes from CAD-DMLS device (computer aided design-direct metal laser sintering device) (TiGrade 5), Ti₆Al₄V grade 23 as it comes from a CAD-CAM milling device (TiGrade 23), and CAD-DMLS TiGrade 5 polished with an abrasive disc (TiGrade 5 polished). Bacterial adhesion on the implants was completed with and without saliva treatment to mimic both extraoral and intraoral surgical methods of implant placement. Five specimens/implant types were used in the bacterial adhesion experiments. Autoclaved implant specimens were placed in petri plates and immersed in saliva solution for 30 min at room temperature and then washed 3× with 1× PBS. Bacterial suspensions of each strain were made and added to the specimens after saliva treatment. Biofilm was allowed to form for 24 h at 37 °C and the adhered bacteria was calculated. Tooling techniques had an insignificant effect on the bacterial adhesion by all the bacterial strains studied. However, there was a significant difference in biofilm formation between the saliva-treated and non-saliva-treated implants. Saliva contamination enhanced S. mutans, S. aureus, and E. faecalis adhesion in all material types studied. S. aureus was found to be the most adherent strain in the saliva-treated group, whereas E. coli was the most adherent strain in the non-saliva-treated group. In conclusion, CAD-CAM tooling techniques have little effect on bacterial adhesion. Saliva coating enhances the biofilm formation; therefore, saliva contamination of the implant must be minimized during implant placement. Further extensive studies are needed to evaluate the effects of surface treatments of the titanium implant on soft tissue response and to prevent the factors causing implant infection and failure. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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Review

Jump to: Research

11 pages, 688 KiB

Open AccessReview

Titanium Implants Coated with Hydroxyapatite Used in Orbital Wall Reconstruction—A Literature Review

by Victor A. Vasile, Ruxandra A. Pirvulescu, Raluca C. Iancu, Gerhard Garhöfer, Leopold Schmetterer, Aurelian M. Ghita, Diana Ionescu, Sinziana Istrate, Roxana M. Piticescu, Laura M. Cursaru and Alina Popa-Cherecheanu

Materials 2024, 17(7), 1676; https://0-doi-org.brum.beds.ac.uk/10.3390/ma17071676 - 05 Apr 2024

Viewed by 537

Abstract

With the increasing incidences of orbital wall injuries, effective reconstruction materials and techniques are imperative for optimal clinical outcomes. In this literature review, we delve into the efficacy and potential advantages of using titanium implants coated with nanostructured hydroxyapatite for the reconstruction of the orbital wall. Titanium implants, recognized for their durability and mechanical strength, when combined with the osteoconductive properties of hydroxyapatite, present a potentially synergistic solution. The purpose of this review was to critically analyze the recent literature and present the state of the art in orbital wall reconstruction using titanium implants coated with nanostructured hydroxyapatite. This review offers clinicians detailed insight into the benefits and potential drawbacks of using titanium implants coated with nanostructured hydroxyapatite for orbital wall reconstruction. The highlighted results advocate for its benefits in terms of osseointegration and provide a novel strategy for orbital reconstruction, though further studies are essential to establish long-term efficacy and address concerns. Full article

(This article belongs to the Special Issue Maxillofacial Prosthetic and Reconstructive Materials)

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