Digital workflow feasibility for the fabrication of intraoral maxillofacial prosthetics after surgical resection: a systematic literature review.

OBJECTIVES: To evaluate the current evidence of digital workflow feasibility based on the data acquisition methods and the software tools used to fabricate intraoral prostheses for patients with partial or total maxillary and mandibular defects. MATERIALS AND METHODS: An electronic search was performed in PubMed, SCOPUS, and Web of Science using a combination of relevant keywords: digital workflow, digital designing, computer-assisted design-computer aided manufacturing, 3D printing, maxillectomy, and mandibulectomy. The Joanna Briggs Institute Critical Appraisal Tool was used to assess the quality of evidence in the studies reviewed. RESULTS: From a total of 542 references, 33 articles were selected, including 25 on maxillary prostheses and 8 on mandibular prostheses. The use of digital workflows was limited to one or two steps of the fabrication of the prostheses, and only four studies described a complete digital workflow. The most preferred method for data acquisition was intraoral scanning with or without a cone beam computed tomography combination. CONCLUSION: Currently, the fabrication process of maxillofacial prostheses requires combining digital and conventional methods. Simplifying the data acquisition methods and providing user-friendly and affordable software may encourage clinicians to use the digital workflow more frequently for patients requiring maxillofacial prostheses.

Perception of color mismatch or conspicuous marginal adaptation in extraoral prostheses with eye-tracking.

STATEMENT OF PROBLEM: Color matching and marginal integrity are major challenges when providing extraoral maxillofacial prostheses. Which of the color and marginal harmony features are more important for the extraoral prostheses to be inconspicuous is unclear. Studies on the perception of these prostheses with objective evaluation criteria are lacking. PURPOSE: The purpose of this observational study was to investigate the significance of color mismatch and conspicuous marginal adaptation in the perception of extraoral maxillofacial prostheses using eye-tracking technology. The secondary aim was to evaluate the perception of extraoral maxillofacial prostheses with regard to the observers' sex. MATERIAL AND METHODS: Twenty-seven face images, in 3 groups, representing well-fitting orbital prostheses with a color mismatch (IC), prostheses with a good color match but distinct marginal adaptation (IM), and symmetrical face images, were viewed for 5 seconds by 52 laypeople. Time to first fixation (TFF), fixation duration (FD), and fixation count (FC) at defined areas of interest were recorded and analyzed by an eye-tracking device. Because of the nested structure of data, a sex- and age-adjusted random intercept linear mixed effects model was used to assess the difference between IC, IM, and SI. Bonferroni corrected P values were used for pairwise comparisons. The difference between observers' sex was evaluated with random intercept mixed model by adjusting for age for each image. For repeated measurement analysis, the lm4, lmerTest, and emmeans libraries in R version 4.3.1 (R Foundation for Statistical Computing) were used (α=.05 for all tests). RESULTS: Significant differences were found between the symmetrical image group and other study groups at the facial prosthesis region in all parameters (each P<.001). Observers first focused on the facial prostheses in IC (0.72 seconds) and in IM (0.789 seconds). Longer fixation durations, 1.909, 1.989 seconds for IC and IM (PIC<.001, PIM<.001), respectively, and a higher fixation count for IC (5.28) (P<.001) and for IM (5.45) (P<.001) were recorded on facial prostheses compared with other areas of interest. Women were more focused on the prosthesis than men in the IC and IM groups considering FD (PIC=.003, PIM<.001) and FC values (PIC=.016, PIM<.001, PSI<.001). Fixation duration for women and men was 2.097 seconds and 1.739 seconds in the IC group, 2.219 seconds and 1.78 seconds in the IM group, and 1.364 seconds and 1.222 seconds in the SI group, respectively. CONCLUSIONS: Since the color mismatch and distinct marginal adaptation of maxillofacial prostheses were recognized using eye-tracking technology, both features appeared to be equally significant to be considered in fabrication procedures.

Microwave disinfection of facial silicone prostheses, part 2: Mechanical properties.

STATEMENT OF PROBLEM: Part 1 of this 2-part study determined that microwave disinfection did not degrade the color stability of facial silicone prostheses. However, investigations on the effects of microwave disinfection on the mechanical properties of different silicone elastomers are lacking. PURPOSE: The purpose of this in vitro study was to examine the mechanical properties of commonly used colored facial silicone elastomers before and after microwave disinfection over a simulated 1.5-year period. MATERIAL AND METHODS: Six commonly used facial silicone elastomers: MDX4-4210, MDX4-4210/Type A, M511, A-2186, VST-50, and A-2000 were combined with functional intrinsic silicone pigments and opacifier (red, yellow, blue, and white). A total of 288 specimens were fabricated (n=12). Half of the specimens were tested for mechanical properties as the baseline, while the other specimens were tested after microwave disinfection. Microwave disinfection was performed with 660 W, 6 minutes of exposure time, and microwaved for 18 cycles to simulate 1.5 years of usage (one 6-minute exposure monthly). For mechanical property testing, all specimens were tested for tensile strength and percentage elongation (ASTM D412), tear strength (ASTM D624), and hardness (ASTM D2240). For each property, a 2-way ANOVA (silicone type and microwave disinfection factors) and Tukey multiple comparison test were performed using the R statistical software program (α=.05). RESULTS: Following microwave disinfection, tensile strength and percentage elongation of A-2000 increased significantly (P<.05). MDX4-4210, MDX4-4210/Type A, and A-2000 showed significant increases in their hardness (P<.001). Tear strength also increased significantly for MDX4-4210 and VST-50 (P<.05). Among the materials tested (ranked from highest to lowest value,=not statistically significant different), for tensile strength, VST-50>A-2186=A-2000>MDX4-4210/Type A=M511=MDX4-4210 (P<.05). For percentage elongation, VST-50>MDX4-4210/Type A>A-2186>M511=A-2000=MDX4-4210=M511 (P<.05). For hardness, A-2000=A-2186>M511=VST-50>MDX4-4210>MDX4-4210/Type A (P<.05). For tear strength, VST-50>A-2186>A-2000>M511>MDX4-4210/Type A=MDX4-4210 (P<.05). CONCLUSIONS: Overall, the mechanical properties of all the silicones tested were not adversely affected by microwave disinfection. VST-50 showed the best mechanical properties among the materials tested both before and after microwave disinfection. Microwave energy is a safe method of disinfecting the silicone elastomers tested in this study.

The future of maxillofacial prosthodontics in North America: The role of advanced digital technology and artificial intelligence - A discussion document.

STATEMENT OF PROBLEM: Maxillofacial prosthodontists were advanced digital technology (ADT) adopters early in the new Millennium. The past two decades saw a range of digital enablers emerge including digital imaging (internal and surface), digital surgical planning, digital functional assessment, subtractive and additive manufacturing, navigation, and robotics among others. Artificial Intelligence (AI) is the latest ADT arrival that will be a challenging disruptive technology. ADT has served as a profound change agent in maxillofacial prosthodontics. The intent was to explore the process and level of ADT engagement in maxillofacial prosthodontics. PURPOSE: The purpose was twofold. Firstly, to explore maxillofacial prosthodontic engagement of ADT. Secondly, to develop a discussion document to assist the American Academy of Maxillofacial Prosthetics (AAMP) with establishing a collective awareness and considered opinion on the future of maxillofacial prosthodontics in the digital era. MATERIAL AND METHODS: AAMP member interest in ADT was assessed through analysis of AAMP annual congress programs and publications in the Journal of Prosthetic Dentistry (JPD). The history of the maxillofacial prosthodontic journey to the digital era was undertaken with a selective literature review. The perceptions maxillofacial prosthodontists hold on ADT engagement was assessed through a survey of AAMP members. Developing an understanding of the influence AI was conducted with a review of pertinent literature. RESULTS: From 2011-2020, an annual mean of 38% of papers published in the JPD involved clinical use of ADT. From 2017-2019, 44% of invited presentations at AAMP annual congresses included clinical use of ADT. The journey to the digital era distinguished three periods with formative and consolidation periods influencing the innovation digital era. The AAMP member survey had a 59% response rate and studied 10 domains through 31 questions. Of the respondents, 89% thought ADT important to the future of maxillofacial prosthodontics. CONCLUSIONS: The discussion document will assist the AAMP in developing a collective consciousness and considered opinion on ADT in the future of maxillofacial prosthodontics. Members of the AAMP have a developed interest in clinical applications of ADT. A great challenge is that no formal education, training, or clinical competency requirements for ADT could be identified. Clinical competency requirements are important to prepare maxillofacial prosthodontics for the inevitability of a digital era future. The discussion document poses the fundamental question of whether maxillofacial prosthodontists will remain as passive end users of ADT and AI or will they become engaged knowledge workers that have determined clinical competency in ADT and AI in patient care. Without this knowledge worker role, maxillofacial prosthodontists may experience difficulty being part of the inevitable ADT-AI driven future.

Microwave disinfection of facial silicone prostheses, Part 1: Color stability.

STATEMENT OF PROBLEM: The choice of cleaning method is an important consideration for lengthening the serviceable time of facial prostheses as microbial organisms and biofilms could degrade facial prostheses and cause skin irritation. Whether microwave disinfection is a suitable cleaning method without degradation of the properties of a prosthesis is unclear. PURPOSE: The purpose of this in vitro study was to measure the color stability of 6 commonly used facial silicone elastomers after microwave disinfection over a simulated 1.5-year period. MATERIAL AND METHODS: Six different facial silicone elastomers: MDX4-4210, MDX4-4210/Type A, M511, A-2186, VST-50, and A-2000 were mixed with intrinsic silicone white opacifier (except for the control group) and subsequently combined with 4 silicone intrinsic pigment color groups: red (R), yellow (Y), burnt sienna (B), and a mixture of R+Y+B (M). The control group was a silicone elastomer without opacifier or pigment. Each of the 30 experimental groups consisted of 5 specimens (N=150). Five specimens were placed in a 250-mL Erlenmeyer flask filled with 160 mL of tap water. Seven flasks were then placed in a 660-W microwave oven. An exposure of 6 minutes was used according to the antimicrobial efficacy of microwave disinfection protocol on facial silicone prostheses with a final water temperature of 60 °C for 18 times (simulating 1.5 years of microwave disinfection with one 6-minute exposure monthly). A spectrophotometer was used to measure reflectance color change values (∆E). Color differences were calculated following CIELab (∆E*ab) and CIEDE2000 (∆E00) formulae. ∆E*ab and ∆E00 were statistically analyzed by a linear mixed effects model with 3 factors (silicone type, color shade, and time) using the R Statistical software program (α=.05). RESULTS: Both ∆E*ab and ∆E00 of all silicone elastomers studied were less than the visual perceptibility thresholds (∆E*ab<1.1 and E00<0.7) and were considered clinically acceptable (∆E*ab<3.0 and E00<2.1) after the 1.5-year simulation of microwave disinfection. Yellow and blue pigments had more effect on MDX4-4210 and M511, while red pigment had more effect on MDX4-4210, MDX4-4210/Type A, and M511 (P<.05). Nevertheless, the values were still below the perceptibility threshold (∆E*ab≤1.0 and E00<0.6). CONCLUSIONS: All 6 facial silicone elastomers maintained clinically acceptable color after 18 months of exposure to microwave disinfection.

Age-related knowledge deficit and attitudes towards oral implants: Survey-based examination of the correlation between patient age and implant therapy awareness.

BACKGROUND: Implantology, as a recognized therapeutic approach, is gaining prominence. The decision-making process and success of implant therapy are closely linked to patient knowledge and expectations. This study aims to explore the association between age and knowledge regarding oral implants. METHODS: Participants were categorized into three age groups (ag): ag 1 (35-44 years), ag 2 (65-74 years), and ag 3 (75 years and older). A total of 400 participants per age group were randomly selected using data from the residents' registration office of Berlin, Germany. Structured telephone interviews were conducted between 2016 and 2017, employing a 67-item questionnaire covering awareness, information level, cost estimation, attitudes, and experiences with oral implants. RESULTS: Despite a low overall knowledge level across all age groups, there was no significant correlation between age and knowledge about oral implants. Awareness increased with age. Information sources varied, with friends, acquaintances, and dentists playing key roles. Participants expressed diverse opinions on implants, with durability and stability identified as crucial characteristics. Significant differences in knowledge were observed between age groups regarding awareness, information sources, and perceptions of dentists offering implants. CONCLUSIONS: The study suggests a need for targeted educational programs, emphasizing age-appropriate information sources to enhance health literacy in oral implantology, particularly among older individuals. Educating physicians on oral implant basics is also crucial. Implementing these measures could empower individuals to make informed decisions about oral implant treatment, thereby contributing to improved oral health outcomes.

The effect of preoperative clindamycin in reducing early oral implant failure: a randomised placebo-controlled clinical trial.

OBJECTIVES: To assess the effect of preoperative oral clindamycin in reducing early implant failure in healthy adults undergoing conventional implant placement. MATERIALS AND METHODS: We conducted a prospective, randomised, double-blind, placebo-controlled clinical trial in accordance with the ethical principles and Consolidated Standards of Reporting Trials statement. We included healthy adults who underwent a single oral implant without previous infection of the surgical bed or the need for bone grafting. They were randomly treated with a single dose of oral clindamycin (600 mg) 1 h before surgery or a placebo. All surgical procedures were performed by one surgeon. A single trained observer evaluated all patients on postoperative days 1, 7, 14, 28, and 56. Early dental implant failure was defined as the loss or removal of an implant for any reason. We recorded the clinical, radiological, and surgical variables, adverse events, and postoperative complications. The study outcomes were statistically analysed to evaluate differences between the groups. Furthermore, we calculated the number required to treat or harm (NNT/NNH). RESULTS: Both the control group and clindamycin group had 31 patients each. Two implant failures occurred in the clindamycin group (NNH = 15, p = 0.246). Three patients had postoperative infections, namely two placebo-treated and one clindamycin-treated, which failed (relative risk: 0.5, CI: 0.05-5.23, absolute risk reduction = 0.03, confidence interval: - 0.07-0.13, NNT = 31, CI: 7.2-∞, and p = 0.5). One clindamycin-treated patient experienced gastrointestinal disturbances and diarrhoea. CONCLUSIONS: Preoperative clindamycin administration during oral implant surgery in healthy adults may not reduce implant failure or post-surgical-complications. CLINICAL RELEVANCE: Oral clindamycin is not efficacy. TRIAL REGISTRATION: The present trial was registered (EudraCT number: 2017-002,168-42). It was approved by the Committee for the Ethics of Research with Medicines of Euskadi (CEIm-E) on 31 October 2018 (internal code number: 201862) and the Spanish Agency of Medicines and Medical Devices (AEMPS) on 18 December 2018.

Opacifiers on color stability of maxillofacial silicone under aging and Indian weathering conditions: An in vitro study.

STATEMENT OF PROBLEM: Resistance to long-term color change is a desirable property for facial prosthetic elastomers. Evidence for the color stability of maxillofacial silicones under aging and hot and humid Indian weathering conditions is lacking. PURPOSE: The purpose of this in vitro study was to evaluate the effect of adding opacifiers on the color stability of maxillofacial silicone under human aging and Indian weather conditions. MATERIAL AND METHODS: A total of 93 specimen disks were obtained from the A-2186, platinum-based, room-temperature vulcanized, maxillofacial silicone elastomer by using a Ø30×6-mm stainless-steel die. The specimens were divided into 3 main groups (n=30), C (control), T (titanium dioxide), and B (barium sulfate), and 1 additional specimen (n=1) from each group was stored in a closed box and further subgrouped as outdoor weathering (COut, TOut, BOut), acidic perspiration (CAcid, TAcid, BAcid), sebum (CSebum, TSebum, BSebum) (n=10), and visual comparison (CVis, TVis, BVis) (n=1). Baseline L∗, a∗, b∗ values were recorded by using a spectrophotometer and visual perception. The specimens were subjected to human and extraoral aging conditions, and the values were recorded again after 6 months. Data were analyzed statistically by using analysis of variance (ANOVA) and post hoc analysis with the Tukey post hoc test. RESULTS: In group C, the mean color change for COut was 3.69 ±0.49; CAcid, 3.58 ±0.68; and CSebum, 7.53 ±0.22 (P<.001). In group T, the mean color change for TOut was 2.60 ±0.24; TAcid, 2.35 ±0.13; and TSebum, 4.91 ±0.44 (P<.001). In group B, BOut was 1.59 ±0.28, BAcid was 1.46 ±0.28, and BSebum was 4.03 ±0.71 (P<.001). The specimens containing barium sulfate showed the maximum color stability. The least color stability was observed in all specimens exposed to sebum solution and was significantly different (P<.001) from the outdoor weather and acidic perspiration specimens. Visually perceivable color changes were observed in specimens exposed to the sebum solution. CONCLUSIONS: The addition of titanium dioxide and barium sulfate as opacifiers resulted in clinically acceptable color change when exposed to outdoor weathering and acidic perspiration but not in sebum solution.

Titanium versus zirconia complete arch implant-supported fixed prostheses: A comparison of plaque accumulation.

STATEMENT OF PROBLEM: Complete arch implant-supported zirconia prostheses appear to have less plaque accumulation than titanium prostheses, but a comparison of the materials and the possible influence on the adjacent soft tissue is lacking. PURPOSE: The purpose of this clinical study was to compare the plaque accumulation and soft-tissue inflammation of complete arch implant-supported fixed maxillary prostheses fabricated with either a titanium framework or monolithic zirconia. MATERIAL AND METHODS: Twenty participants with a complete arch implant-supported fixed maxillary prosthesis were enrolled in the study. The participants were divided into 2 groups according to the prosthesis material, titanium (Ti) or zirconia (Zir). The prosthesis had to have been in function for at least 6 months, and participants were examined during at least 3 maintenance appointments at 3-month intervals. Clinical information collected in each appointment included standardized photographs to record the Plaque Area Index (PAI) of the intaglio surface of the prosthesis; clinical parameters including modified Plaque Index (mPI), modified Bleeding Index (mBI), implant mobility (MOB), probing depths ≥5 mm (PD), suppuration (SUP), keratinized tissue band ≥2 mm (KT), and an intraoral photograph of the maxillary arch without the prosthesis to evaluate the redness of the soft tissues. RESULTS: MOB was not present at any implant at any time point. SUP could not be analyzed because it was an infrequent finding. Both groups exhibited significant increases in mBI over time. No significant differences were observed for PD between the groups at any time point. Implants in the Ti group had significantly higher KT values than those in the Zir group; levels remained constant over time for both groups. Zirconia prostheses had slightly lower PAI levels than Ti prostheses. The PAI in the Zir group significantly decreased over time (P=.035); in the Ti group, they remained constant (P=.45). Higher PAI levels were correlated with increased levels of erythema; both groups had a significant decrease in erythema values over time (P=.04). CONCLUSIONS: Zirconia complete arch implant-supported fixed maxillary prostheses displayed a significant decrease in plaque accumulation in individuals who had received periodic maintenance and oral hygiene instructions. Ti prostheses had significantly higher plaque levels than zirconia prostheses at all time points, which was not reduced by maintenance and oral hygiene measures. The present study suggests that patients receiving zirconia prostheses respond well to plaque control measures, while plaque control for those with titanium prostheses may be more challenging.

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

STATEMENT OF PROBLEM: Silicone 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. PURPOSE: The 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 METHODS: Six 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). RESULTS: Benzophenone-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. CONCLUSIONS: Ethylhexyl salicylate protective incorporated into maxillofacial silicones may improve color stability.

Digital fabrication of a maxillary obturator prosthesis by using a 3-dimensionally-printed polyetheretherketone framework.

The digital fabrication of a maxillary obturator with a 3D-printed polyetheretherketone (PEEK) framework is described. Digital oral data were scanned for the computer-aided design (CAD) of the framework and the 3D printing of a preliminary resin cast. The framework was accurately printed from a PEEK filament material. A secondary impression was made to fabricate the definitive cast. The PEEK framework exhibited precise fit, excellent retention, and reduced weight compared with a typical metal framework.

Improvement of speech by facial prosthesis in a midfacial defect with a gunshot injury: A case report.

Gunshot wounds in the maxillofacial region may cause serious defects that result in functional and esthetic disabilities. A 14-year-old male patient was referred to the prosthodontics clinic for provisional prosthetic restoration 5 months after an injury involving the midline midfacial region. An interim extraoral silicone maxillofacial prosthesis (MFP), also known as an epithesis, replacing the nose and upper lip, was fabricated to enhance appearance and speech intelligibility. The effect of the prosthesis insertion on speech outcome was assessed over 6 months. Blood pulse oxygen saturation levels and heart rate were monitored to assess ventilation following the prosthesis insertion. Results of the Assessment of Articulation Subtest revealed the patient produced the target speech sounds of 31 more words correctly at 6 months follow-up. Bilabial, labiodental, and postalveolar speech sounds in the phonetic inventory improved. Fabrication of an extraoral silicone MFP, modifying substructure design, and prosthesis usage over time contributed to the significant enhancement of speech intelligibility and did not significantly change the blood pulse oxygen saturation levels and heart rate. It led to an improvement in overall aesthetic outcomes and was a useful tool for the patient's social integration.

Maxillary Obturator Prosthesis Made with Polyetherketoneketone Using Optical Impression and CAD/CAM System.

This report describes the case of a 68-year-old man who visited our department complaining of poor denture retention and difficulty masticating due to damage to the retainer of a maxillary obturator. The patient had never been satisfied with the fit of this prosthesis, which had been placed two years earlier. The obturator and the mucosal surface of the denture base were incompatible, which had caused the retainer to detach. The maxillary defect was categorized as H3S0D0T0 according to the HS classification. The diagnosis was a masticatory disorder due to a damaged retainer and an incompatible denture base. Optical impressions and occlusal records were taken and a maxillary obturator fabricated using a CAD/CAM system. Dental CAD software was used to design and complete the tooth arrangement. The CAM system was used to mill a polyetherketoneketone disc based on the obtained data and composite resin used to face the teeth and gingiva. The maxillary obturator was placed after only three visits, spanning from impression taking to denture completion. The use of digital data allowed the time to denture completion to be shortened in addition to the number of hospital visits to be reduced. Compared to conventional impression taking, optical impressions also prevent discomfort, decreasing stress for the patient.

[Modern methods of adhesive fixation of facial epitheses]. / Sovremennye metody adgezivnoi fiksatsii epitezov litsa.

This review presents an analysis of domestic and foreign literature on the issues of fixation of facial epitheses and combined maxillofacial prostheses, such as the use of craniofacial implants installed in the zygomatic bone, brow arches, orbital walls, mastoid process of the temporal bone with beam or magnetic beam fixation systems. The advantages and disadvantages of such fastening systems are described. The analysis and systematization of available data on medical adhesive compositions that can be used in maxillofacial prosthetics to hold facial epitheses has been carried out. Much attention is paid to the chemical composition of pressure-sensitive adhesives, water-based and silicone-based. Examples of such compositions are given. The physicochemical properties of medical adhesive systems that cause adhesive-cohesive interaction are described. This review presents the results of comparative studies to assess the fixing properties of various adhesives, as well as to study the formation of biofilm on the surfaces of prostheses and skin when using different adhesives.

Facial Scanning and Additive Manufacturing Used in Production Nasal Prosthesis.

Maxillofacial prosthesis is an effective treatment for patients with facial sequelae, but it remains challenging for professionals due to its high esthetic complexity. This study describes a clinical case of successful nasal prosthetic rehabilitation using digital technology and additive manufacturing. Initially, the 76-year-old patient, with a facial defect in the nasal region, had her face scanned with 3-dimensional scanner for laboratory planning of the prototype of a nasal prosthesis. After approving the prototype image, working models in muffle shape were obtained in additive manufacture for the inclusion of the prosthesis. In the final session, the prosthesis was colored extrinsically and installed. The procedures digital in the manufacture of the facial prosthesis was applicable and agile, allowing the professional greater predictability regarding the shape of the rehabilitated organ, esthetic improvement in the mutilated area and patient satisfaction in relation to the speed, of the procedure and the quality of the prosthesis.

Percentage of mesh reduction appropriate for designing digital obturator prostheses on personal computers.

STATEMENT OF PROBLEM: Computer-aided design (CAD) of maxillofacial prostheses is a hardware-intensive process. The greater the mesh detail is, the more processing power is required from the computer. A reduction in mesh quality has been shown to reduce workload on computers, yet no reference value of reduction is present for intraoral prostheses that can be applied during the design. PURPOSE: The purpose of this simulation study was to establish a reference percentage value that can be used to effectively reduce the size and polygons of the 3D mesh without drastically affecting the dimensions of the prosthesis itself. MATERIAL AND METHODS: Fifteen different maxillary palatal defects were simulated on a dental cast and scanned to create 3D casts. Digital bulbs were fabricated from the casts. Conventional bulbs for the defects were fabricated, scanned, and compared with the digital bulb to serve as a control. The polygon parameters of digital bulbs were then reduced by different percentages (75%, 50%, 25%, 10%, 5%, and 1% of the original mesh) which created a total of 105 meshes across 7 mesh groups. The reduced mesh files were compared individually with the original design in an open-source point cloud comparison software program. The parameters of comparison used in this study were Hausdorff distance (HD), Dice similarity coefficient (DSC), and volume. RESULTS: The reduction in file size was directly proportional to the amount of mesh reduction. There were minute yet insignificant differences in volume (P>.05) across all mesh groups, with significant differences (P<.001) in HD. The differences were, however, only found with DB1. DSC showed a progressive dissimilarity until DB25 (0.17%), after which the increase was more prominent (0.46% to 4.02%). CONCLUSIONS: A reduction of up to 75% polygons (25% of the original mesh) was effectively carried out on simulated casts without substantially affecting the amount of similarity in volume and geometry.

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

STATEMENT OF PROBLEM: A 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. PURPOSE: The 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 METHODS: Sixty 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. RESULTS: ANOVA 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. CONCLUSIONS: Nano-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.

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

STATEMENT OF PROBLEM: Silicone 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. PURPOSE: The 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 METHODS: Nano-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). RESULTS: FESEM 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. CONCLUSIONS: Sonication 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.

Visual and instrumental color evaluation of computerized color matching system for color reproduction of maxillofacial prostheses.

STATEMENT OF PROBLEM: A commercially available computerized color matching system (e-Skin) has been introduced for maxillofacial prostheses. However, studies that have tested its ability to produce an acceptable color match for skin color are lacking. PURPOSE: The purpose of this clinical study was to determine the color match acceptability of light and dark skin silicone replicas fabricated with the use of the computerized color matching system. MATERIAL AND METHODS: Fifteen participants with light skin and 15 participants with dark skin were recruited through personal invitation. These 30 participants (aged around 20 years) voluntarily consented to forearm skin color measurements with a spectrophotometer and a spectrocolorimeter integrated in a computerized color matching system. Silicone skin replicas for each participant were produced from the color formulations provided by the online calculator tool of the system according to the manufacturers' recommendations. The color difference between initial skin color measurements with the spectrophotometer and skin replica color measurements with the spectrophotometer for all participants was calculated by using both the CIELab (ΔE∗ab) and CIEDE2000 (ΔE00) color difference formulas. To compare the instrumental and visual evaluation of color match, 3 observers (a maxillofacial prosthodontist, a prosthodontist, and a postgraduate student) visually evaluated and rated the color match of each silicone replica on a 5-point scale. Statistical analyses were performed by using the Student t, Mann Whitney U, and chi-square tests (α=.05). RESULTS: No significant differences were detected between the light and dark skin groups in terms of the ΔE∗ab and ΔE00 values obtained between the first skin color measurements and their silicone replica color measurements (P=.573, P=.338, respectively). However, a significant difference was found between light and dark skin groups for the ΔL and Δa values obtained from the same measurements (P=.031, P=.017, respectively). L∗, a∗, and b∗ values of light skin were significantly higher than those of their silicone replications (P=.008, P=.033, P=.046, respectively). Color match ratings of observers did not significantly differ when comparing the ratings of light skin replicas to ratings of dark skin replicas. CONCLUSIONS: The e-Skin system provided skin replicas that matched the skin color within clinically acceptable thresholds and with ratings of at least "good" by experienced dental clinicians.

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

STATEMENT OF PROBLEM: The 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. PURPOSE: The 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 METHODS: Type-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). RESULTS: After 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. CONCLUSIONS: Based 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.