A statistical shape model for estimating missing soft tissues of the face in a black South African population.

PURPOSE: Facial disfigurement may affect the quality of life of many patients. Facial prostheses are often used as an adjuvant to surgical intervention and may sometimes be the only viable treatment option. Traditional methods for designing soft-tissue facial prostheses are time-consuming and subjective, while existing digital techniques are based on mirroring of contralateral features of the patient, or the use of existing feature templates/models that may not be readily available. We aim to support the objective and semi-automated design of facial prostheses with primary application to midline or bilateral defect restoration where no contralateral features are present. Specifically, we developed and validated a statistical shape model (SSM) for estimating the shape of missing facial soft tissue segments, from any intact parts of the face. MATERIALS AND METHODS: An SSM of 3D facial variations was built from meshes extracted from computed tomography and cone beam computed tomography images of a black South African sample (n = 235) without facial disfigurement. Various types of facial defects were simulated, and the missing parts were estimated automatically by a weighted fit of each mesh to the SSM. The estimated regions were compared to the original regions using color maps and root-mean-square (RMS) distances. RESULTS: Root mean square errors (RMSE) for defect estimations of one orbit, partial nose, cheek, and lip were all below 1.71 mm. Errors for the full nose, bi-orbital defects, as well as small and large composite defects were between 2.10 and 2.58 mm. Statistically significant associations of age and type of defect with RMSE were observed, but not with sex or imaging modality. CONCLUSION: This method can support the objective and semi-automated design of facial prostheses, specifically for defects in the midline, crossing the midline or bilateral defects, by facilitating time-consuming and skill-dependent aspects of prosthesis design.

Accuracy of capturing nasal, orbital, and auricular defects with extra- and intraoral optical scanners and smartphone: An in vitro study.

OBJECTIVES: This in vitro study compares the scanning accuracy of various stationary and portable as well as extra- and intraoral devices for capturing oncological defects. METHODS: A 3D-printed model of a nasal, orbital, and auricular defect, as well as one of an intact auricle, were digitalized (n = 7 per device) with a stationary optical scanner (Pritiface), a portable extraoral optical scanner (Artec Space Spider), two intraoral scanners (Trios 4 and Primescan), and a smartphone (iPhone 11 Pro). For the reference data, the defect models were digitalized using a laboratory scanner (D2000). For quantitative analysis, the root mean square error value for trueness and precision and mean deviations in millimeters were obtained for each defect type. The data were statistically analyzed using two-way ANOVA and Tukey multiple comparison test. For qualitative analysis, a colorimetric map was generated to display the deviation within the defect area and adjacent tissue. RESULTS: Statistically significant interactions were found in the trueness and precision for defect and scanner type. CONCLUSION: The Primescan and Artec Space Spider scanners showed the highest accuracy for most defect types. Primescan and Trios 4 failed to capture the orbital defect. The iPhone 11 Pro showed clinically acceptable trueness but inferior precision. CLINICAL SIGNIFICANCE: The scanning devices may demonstrate varying accuracy, depending on the defect type. A portable extraoral optical scanner is an universal tool for the digitization of oncological defects. Alternatively, an intraoral scanner may be employed in maxillofacial prosthetics with some restrictions. Utilizing a smartphone in maxillofacial rehabilitation should be considered with caution, because it provides inconsistent accuracy.

Bonding strength of 3D printed silicone and titanium retention magnets for maxillofacial prosthetics application.

PURPOSE: To assess the bonding between conventional and additively manufactured silicone elastomers and cylindrical retention titanium magnets for anchorage of facial prostheses. METHODS: The customized titanium retention magnets were embedded in conventional and additively produced silicone blocks without primer application (n = 20) and with two commercially available primers G611 (n = 20) and A304 (n = 20) applied onto the magnet surface. The pull out test was performed in the universal testing machine using 45° and 90° angulation and the pull out strength was measured for each group. Additionally the SEM images of the pulled out magnets' surface were obtained and the amount of residual silicone onto the magnet surface was quantified. RESULTS: Significantly higher pull out strength values (p < 0.05) were revealed for 90° specimens (0.11 - 0.17 ± 0.01 N/mm2) compared to the 45° group (0.03 ± 0.02 N/mm2). The pull out test with primer revealed no significant differences between the G 611 and A 304 primers in the additive group. However, significantly (p < 0,05) higher values were observed for conventional specimens in the A304 group (1.10 ± 0.21 N/mm2) compared to the G611 group (0.59 ± 0.27 N/mm2). CONCLUSION: The application of both used primers may be an acceptable technical option for the anchorage of retention titanium magnets in silicone facial prostheses, produced additively in a fully digital workflow.

Retention systems used in maxillofacial prostheses: A review.

Defects in the face area caused by trauma, accident, tumor or congenital defects are treated with special facial prostheses. Besides esthetics, the most common problem with these prostheses is the retention of prostheses. In the present article review, the methods used for the retention of prostheses from past to present were researched, and the advantages of adhesives and implants, which are the most commonly used current methods, were evaluated. Current techniques, new materials, treatment options, and implementation procedures are described. The success of maxillofacial prostheses in meeting the expectations of patients and dentist doctors is increasing day by day with the development of adhesive material science, the emergence of technical knowledge, and the development of implant technology. Increasing the retention provides both ease of use and acceptance by the patient. Therefore, the chosen method for retention has great importance in the long-term prognosis of the prosthesis.

Effect of Aging and Weathering on the Physical Properties of Maxillofacial Silicone Elastomers: A Systematic Review and Meta-Analysis.

PURPOSE: This systematic review aims to identify and interpret results of studies that evaluated the changes in the physical properties of maxillofacial prosthetic materials (1) without aging, (2) after natural or artificial accelerated aging, and (3) after outdoor weathering. METHODS: Relevant articles written in English only, before January 15, 2017, were identified using an electronic search in the PubMed, Scopus, and Google Scholar databases. Furthermore, a manual search of the related major journals was also conducted to identify more 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 37 articles satisfied the criteria, from which data were extracted for qualitative synthesis. RESULTS: Among the 37 included articles, 14 were without aging, 15 were natural or artificial accelerated aging, 7 were outdoor weathering, and 1 contained both artificial aging and outdoor weathering. Only 4 studies out of the 14 without aging had significant observations; whereas 9 articles with natural or artificial aging published significant results, and 3 out of 7 outdoor weathering articles showed significant changes in the evaluated silicone elastomers. CONCLUSIONS: Despite the varying research, it seems that the single "ideal" maxillofacial prosthetic material that can provide sufficient resistance against different aging conditions is yet to be identified. Therefore, it is imperative for standardization organizations, the scientific community, and academia to develop modified prosthetic silicones possessing improved physical properties and color stability, limiting the clinical problems regarding degradation of maxillofacial prostheses.

Mechanical and Morphological Effect of Plant Based Antimicrobial Solutions on Maxillofacial Silicone Elastomer.

The objective of this study was to determine the effect of plant based antimicrobial solutions specifically tea tree and Manuka oil on facial silicone elastomers. The purpose of this in vitro study was to evaluate the effect of disinfection with plant extract solution on mechanical properties and morphology on the silicone elastomer. Test specimens were subjected to disinfection using tea tree oil, Manuka oil and the staphylococcus epidermidis bacteria. Furthermore, a procedure duration was used in the disinfection process to simulate up to one year of usage. Over 500 test specimens were fabricated for all tests performed namely hardness, elongation, tensile, tear strength tests, visual inspection and lastly surface characterization using SEM. A repeated measures ANOVA revealed that hardness and elongation at break varied significantly over the time period, whereas this was not observed in the tear and tensile strength parameters of the test samples.

Estudo de comparação por extensometria entre dois modelos de implante: extraoral e intraoral (estudo piloto) / Comparison study for extensometry between two implant models: extra-oral and intraoral (pilot study)

Objetivo: avaliar, por meio de extensometria, a infl uência da flange do implante de titânio na deformação superficial do osso. Material e métodos: um bloco de poliuretano simulando um osso tipo I mais corticalizado e menos medular (40 PCF) recebeu um implante de hexágono externo intraoral, sem flange 3,75 mm x 8,5 mm (G1) e um implante de hexágono externo extraoral, com flange 3,75 mm x 8 mm (G2). Em seguida, foram instalados componentes standard com 2 mm de altura de cinta metálica e cilindros metálicos para restauração provisória. Dois extensômetros lineares foram colados na superfície do bloco (mesial e distal de cada implante), e uma carga axial de 100 Ncm em uma máquina de ensaio universal foi aplicada, com cinco medições de microdeformação (µÎµ) para cada implante. Os dados foram submetidos ao teste Shapiro-Wilk para verifi car a homogenidade dos dados e em seguida ao teste t Student. Resultados: as médias e desvios-padrão obtidos foram: G1: 148,2 ± 5,84 e G2: 92,4 ± 11,24 µÆ, com diferença estatística significativa entre os grupos. Conclusão: os implantes extraorais tiveram melhor comportamento mecânico para as cargas axiais do que os implantes intraorais, sendo que a flange melhorou a distribuição da carga na superfície do bloco de poliuretano.

Objectives: to evaluate, by means of extensometry, the influence of the titanium implant flange on the superficial deformation of the bone. Material and methods: a polyurethane block simulating a more corticalized and less spinal type I bone (40 PCF) received an external intraoral hexagon implant with a 3.75 mm x 8.5 mm fl ange (G1) and an extraoral external hexagon implant, with flange 3.75 mm x 8 mm (G2). Subsequently, standard components with 2 mm high of metal strap and metal cylinders were installed for temporary restoration. Two linear strain gauges were glued to the surface of the block (mesial and distal of each implant), and an axial load of 100N in a universal test machine was applied with five microdemorphometric measurements (µÎµ) for each implant. The data were submitted to the Shapiro-Wilks test to verify the homogeneity of the data and then to the t-student test. Results: the means and standard deviations obtained were: G1: 148.2 ± 5.84 and G2: 92.4 ± 11.24 µÎµ, with signifi cant statistical difference between the groups. Conclusion: extraoral implants had better mechanical behavior for axial loads than intraoral implants, and the flange improved the load distribution on the surface of the polyurethane block.

Immediate Implant Placement and Provisionalization Following Tumor-Resective Surgery in the Midfacial Region: A Case Series.

Surgical and prosthodontic restoration of the midfacial region following tumor resection has always posed a considerable challenge, as this area serves crucial functional and esthetic roles. Being diagnosed and subsequently treated for facial tumors can have an immense psychosocial impact on a patient, as the resulting defects are often disfiguring, and lead to an inability to masticate, swallow, and speak clearly. Provision of an immediate facial and dental prosthesis at the time of surgery can limit these side effects and help reduce mental duress on these patients and their families, as well as aid in the process of rehabilitation. Rapid prototyping (RP) and 3D printing, as this paper shows, assists presurgical planning of the tumor resection, as well as the manufacture of maxillofacial and dental prostheses. Often these defects are extensive, so prosthesis retention is aided by zygomatic implants placed at the time of surgical resection. When placed at this time, and prior to radiation therapy, these craniofacial implants have improved survival rates. Thus, this treatment modality can improve postoperative recovery considerably, while at the same time allowing for cleaning and monitoring of the resected site for tumor recurrence.

Efficacy of cleansing agents in killing microorganisms in mixed species biofilms present on silicone facial prostheses--an in vitro study.

OBJECTIVES: The purpose of this study was to assess the efficacy of different cleansing agents in killing mixed species biofilms on silicone facial prostheses. MATERIALS AND METHODS: Two bacterial and three yeast strains, isolated from silicone facial prostheses, were selected for the mixed species biofilms. A variety of agents used to clean facial prostheses were employed, viz., antibacterial soap, essential-oil-containing mouth rinse, ethanol 27 %, chlorhexidine mouth rinse, and buttermilk. Colony forming units (CFUs) and live/dead staining were analyzed to assess the efficacy of these cleansing agents against 24-h and 2-week biofilms and regrown biofilms on silicone samples. RESULTS: Chlorhexidine was the most effective cleansing agent. Chlorhexidine killed 8 log unit CFUs (>99.99 % killing) in a 24-h biofilm and 5 log unit CFUs (>99.99 % killing) in 2-week biofilms. Also, after regrowth and repeated treatment of the biofilm, chlorhexidine was the most effective cleansing agent showing no detectable CFUs. The essential-oil-containing mouth rinse (containing 26.9 % ethanol) showed a similar efficacy as ethanol (27 %) alone. Antibacterial soap and buttermilk were the least effective agents tested. CONCLUSIONS: Chlorhexidine showed the highest reduction in CFUs in 24-h, 2-week, and regrown mixed species biofilm of microorganisms isolated from silicone facial prostheses. CLINICAL RELEVANCE: Chlorhexidine mouth rinse (easy obtainable and relatively cheap) is very effective in killing bacteria and yeast present in biofilms on silicone facial prostheses. When applied on a regular basis, cleansing a facial prosthesis with chlorhexidine will presumably increase its lifetime and reduce skin irritations.