Simulation of tissue-prosthesis margin interface by using surface scanning and digital design for auricular prostheses

Statement of problemOne of the most challenging aspects of auricular prosthesis design and fabrication is ensuring that the prosthesis fits the patient through a range of head and facial movements. Techniques used in conventional prosthetic treatment pathways account for issues of prosthesis fit, but this challenge has not been fully addressed in emerging treatment pathways that use digital technology.PurposeThe purpose of this clinical study was to develop and evaluate a digital workflow by using surface scan data and incorporating the simulation of tissue movement into the design of auricular prostheses that fit the participant through a range of facial movements. An iterative design process was used to develop a design workflow through a sequential case series of participants with auricular prostheses.Material and methodsScan data were acquired from a case series of 5 participants with existing implant-retained auricular prostheses. An iterative design process was used to digitally design auricular prostheses that fit the participants through a range of jaw and facial movements. The fit, shape, and retention of the digitally designed and conventionally made prostheses were assessed and compared. Design considerations were identified and documented through the iterative design process.ResultsA final design workflow was iteratively developed based on the 5 participants. The shapes of the digitally designed prostheses were well matched to nontreatment anatomy overall. Prosthesis fit was variable: Some digitally designed prostheses fit the participant intimately through a range of movements, and others experienced significant gaps between the margins and the tissues.ConclusionsAn iterative design process provided a method of working toward quality improvement. Although the final design workflow provides a generally successful method of manipulating scan data in the design of auricular prostheses, the prosthesis fit at the anterior margin during facial movements remains variable and requires further development to achieve a consistently acceptable solution.     

颜面赝复体阴模三维打印成形的初步研究

目的 探讨三维打印在颜面赝复体阴模自动化加工中的可行性.方法 选取鼻数据库中鼻数字化模型1个,利用Magics RP软件生成立体成型格式的鼻阴模.通过三维打印加工鼻石膏模型和鼻阴模石膏模型.将硅橡胶充填于鼻阴模石膏模型中,获得鼻硅橡胶模型.采用结构光三维测量系统扫描鼻石膏模型和硅橡胶模型,进行偏差分析.结果 鼻石膏模型和硅橡胶模型的最大正偏差为0. 98 m,位于鼻尖;最大负偏差为-0. 64 mm,位于鼻小柱;均值为0.17 mm.结论 颜面赝复体阴模直接快速成形具有可行性.     

Direct 3D Printing of Flexible Nasal Prosthesis: Optimized Digital Workflow from Scan to Fit

A maxillofacial prosthesis is a successful treatment modality to restore missing facial parts. Digital technologies and 3D printing are employed in constructing facial prostheses such as ears; however, their application is still partial, and final prostheses are usually manufactured conventionally using stone molds. This report aims to introduce a complete digital workflow to construct a nasal prosthesis and compare it to the conventional workflow of a patient requiring a nasal prosthesis. A computer tomography scan showing the defect was exported to specialized software to create 3D reconstructions of the patient's face and underlying bone. The nose was digitally designed restoring facial esthetics, anatomy, shape, and skin color. Different skin tones were digitally matched to skin tissues adjacent to the defect area using the Spectromatch system. The design was 3D printed in flexible and colorful material at 16 μm resolution using a 3D printer. External color pigmentations were applied to the nose for optimum esthetics, and the prosthetic nose was sealed in silicone and left to heat polymerize for 15 minutes. The prosthetic nose was retained in place using biomedical adhesive, and the patient was pleased with it. This report proposes a complete digital workflow to directly design and fabricate a prosthetic nose of acceptable esthetics. Such a workflow can lead to enhanced prosthesis reproducibility and acceptability and may become an effective treatment option for treatment of patients with facial defects.     

Computer-aided design of facial prostheses by means of 3D-data acquisition and following symmetry analysis

The aim of this study was to investigate whether a method of designing digital models of facial prostheses was suitable for patients with orbital defects. 32 patients were included in a retrospective study. 23 of them already had a facial prosthesis. 3D-data of the faces were acquired optically using fringe projection technique without and with (if available) the facial prosthesis in place. The healthy side of the surface models was mirrored to reconstruct the defect area. By generating a NURBS-model, the edges of the virtual prostheses were adapted to the defect region. The CAD models were stored in STL format as templates for facial prostheses. Using an automatically calculated asymmetry index (AI), four situations of the digitized facial surface were analysed for symmetry: 1. with defect area excluded, 2. with mirrored healthy surface, 3. with digital CAD template, and 4. with manually produced facial prosthesis inserted (if available). Mean AI values were 6.05 ± 3.26 (situation 1), 4.79 ± 2.51 (situation 2), 5.12 ± 2.61 (situation), and 6.74 ± 2.77 (situation 4). Additionally, the CAD templates were rated by three anaplastologists. Ratings did not differ significantly. They partially agreed with the three statements “The CAD prosthesis fits harmoniously within the face”, “The CAD prosthesis could be used for a wax pattern during conventional fabrication” and “The CAD prosthesis and the wax pattern reduce workload”. The results indicate that the presented technique has the potential to increase facial symmetry and facilitate the technical procedure. However, symmetry alone is not a sufficient criterion for design of a facial prosthesis.     

Early Prosthetic Management of Maxillectomy,Hemimandibulectomy Patient with a Lateral Mid Facial Defect: A Case Report

Maxillofacial prostheses for acquired defects have become more complex and sophisticated with advances in surgical, physical, and rehabilitative dentistry, but before planning, orofacial structures must be analyzed as to the specific cause and the consequent objectives of rehabilitation. Also retention of facial prostheses is very much challenging. Hence, we are presenting the fabrication of an interim prosthesis obturator and cheek prosthesis to restore the speech, help in deglutition and prevent drooling of saliva.     

颜面赝复数字化远程诊疗系统的初步建立与临床试用

目的:建立一套颜面赝复数字化远程诊疗系统,并进行临床应用评价.方法:系统采用服务器/浏览器(Server/Brower,B/S架构),基于网络(NET)开发.应用此套系统,通过异地端患者基本信息、照片、CT数据的上传,及本地端数据下载,赝复体CAD设计与快速成型加工,进行1例病例的远程诊疗.结果:建立的颜面赝复数字化远...     

Combined use of a facial scanner and an intraoral scanner to acquire a digital scan for the fabrication of an orbital prosthesis

For a patient with a unilateral orbital defect, an esthetic orbital prosthesis plays an essential role in enhancing quality of life. This technique describes the combined use of a facial scanner and an intraoral scanner to acquire the digital scan for the design and fabrication of an orbital prosthesis. The method results in an esthetic prosthesis with accurate skin texture reproduction.     

Fabrication of a Maxillofacial Prosthesis Using a Computer-Aided Design and Manufacturing System

PURPOSE: Maxillofacial prostheses are usually fabricated on the basis of impressions made with dental-impression material. The extent to which the prosthesis reproduces normal facial morphology depends on the clinical judgment of the individual fabricating the prosthesis. This paper describes a computer-aided design and manufacturing (CAD/CAM) system for the fabrication of maxillofacial prostheses. This system will provide a more consistently accurate reproduction of facial morphology. MATERIALS AND METHODS: Facial measurements were taken using a non-contact three-dimensional laser morphological measurement system. The measurements were sent to a computer numerical controlled (CNC) milling machine to generate a cast of the patient's face for the fabrication of prosthesis. RESULTS: Facial contours were measured using a laser. This method minimizes patient discomfort and avoids soft tissue distortion by impression material. Moreover, the digital data obtained is easy to store and transmit, and mirror-images can be readily generated by computer processing. CONCLUSION: This method offers an objective, quantified approach for fabricating maxillofacial prostheses.     

Maxillofacial prosthetic rehabilitation in the UK: a survey of maxillofacial prosthetists’ and technologists’ attitudes and opinions

Maxillofacial prostheses are constructed by maxillofacial prosthetists and technologists (MPTs), as an alternative treatment when maxillofacial defects cannot be surgically fulfilled. A questionnaire was conducted surveying 220 MPTs working in all UK maxillofacial units about their opinions, attitudes, and experience regarding several aspects related to maxillofacial silicone prostheses. Numbers and percentages of maxillofacial prostheses, their retention method, serviceability, reduced serviceability causes, and digital technologies (DT) used in constructing prostheses were analysed. Thousand hundred and ninety-three prostheses were constructed (42% ocular, 31% auricular, 13% orbital, 12% nasal, 1% composite, more than one facial prosthesis). Adhesives commonly retained orbital (48%) and nasal (45%) prostheses. Implant-retained bars commonly retained auricular prostheses (70%). Ocular prostheses were entirely retained by undercuts. Implant-retained prostheses remained serviceable for twice as long (19–24 months) as adhesive-retained prostheses (7–12 months). Causes for prosthesis replacement included colour changes (71%), poor maintenance (41%), and silicone tear (37%). Thirty-one percent of MPTs used DT computer software and programs for designing and constructing maxillofacial prostheses. In conclusion, adhesives, implant-retained bars and magnets are commonly used retentive methods. Prosthesis failure is caused mainly by colour change, poor maintenance, silicone tear and delamination. Different DTs are used by one-third of MPTs.     

Facially generated and cephalometric guided 3D digital design for complete mouth implant rehabilitation: A clinical report

Harmony among the teeth, lips, and facial components is the goal of prosthodontic treatment, whether performed by conventional or digital workflow methods. This clinical report describes a facial approach to planning computer-guided surgery and immediate computer-aided designed and computer-aided manufactured (CAD-CAM) interim complete-arch fixed dental prostheses on immediately placed dental implants with a digital workflow. A single clinical appointment for data collection included dentofacial documentation with photographs and videos. On these photographs, facial reference lines were drawn to create a smile frame. This digital smile design and sagittal cephalometric analysis were merged with 3-dimensional scanned casts and a cone beam computed tomographic file in virtual planning software, thus guiding virtual waxing and implant positioning. Computer-guided implant surgery and CAD-CAM interim dental prostheses allowed esthetic and functional rehabilitation in a predictable manner and integrated with the patient’s face.     

Extraoral prostheses using extraoral implants

The aim of this study was to evaluate extraoral prostheses and the use of extraoral implants in patients with facial defects. 10 cases were treated utilizing maxillofacial prostheses employing extraoral implants in five cases. 16 extraoral implants were installed. Seven implants were placed in irradiated sites in the orbital regions. Six implants were placed in mastoid regions and three in a zygoma region that was irradiated. Two implants failed before initial integration was achieved in irradiated areas. Using 14 extraoral implants as anchors, five extraoral prostheses were set. The other five cases were treated with extraoral prostheses without using extraoral implants due to cost and patient-related factors. The data included age, sex, primary disease, implant length, implant failure, prosthetic attachment, radiation therapy, and peri-implant skin reactions. The use of extraoral implants for the retention of extraoral prostheses has simplified the placement, removal, and cleaning of the prosthesis by the patient. The stability of the prostheses was improved by anchors. Clinical and technical problems are presented with the techniques used for their resolution. Using extraoral implants resulted in a high rate of success in retaining facial prostheses and gave good stability and aesthetic satisfaction.     

Modal analysis of two different types of fixed implant-supported prostheses embedded in edentulous maxillae

PurposeModal analysis has been used to monitor and quantify the vibration of each component of a prosthesis at its natural frequency. An understanding of the vibrational characteristics of a prosthesis can guide selection of the appropriate prosthesis configuration to prevent excessive stress. In this study, modal analysis of fixed implant-supported prostheses with 4 or 6 abutments in edentulous maxillae was performed.MethodsSixteen patients underwent maxillary dental implant treatment and received screw-fixed implant-supported prostheses (9 patients received 4-abutment prostheses and 7 patients received 6-abutment prostheses) in edentulous maxillae. An impact hammer was used for excitation of the prostheses, and vibration was detected on every crown of the prostheses. The modal parameters were determined in each subject. Furthermore, the modal shapes were compared at each natural frequency.ResultsThe median natural frequencies of subjects with 4- and 6-abutment prostheses were 697 and 781 Hz, respectively. The mean damping ratios did not differ significantly between 4- (8.2 ± 1.7%) and 6-abutment (6.6 ± 1.7%) prostheses (p = 0.125). The mean maximum displacements of fixed prostheses were significantly lower for 6-abutment (10.3 ± 3.3 μm) than for 4- (20.3 ± 9.1 μm) prostheses (p = 0.004). The median number of vectors in antiphase was significantly lower for 6- (4) than for 4-abutment prostheses (14) (p = 0.001).ConclusionsThe current study demonstrated less adverse vibration in the 6-abutment prostheses than in the 4-abutment prostheses, suggesting that modal analysis can contribute to novel future developments in the designs of dental implant prostheses.     

Laser Doppler imaging of skin microcirculation under fiber-reinforced composite framework of facial prosthesis

Objective. Glass-fiber reinforced composite has been suggested to be used as framework material in silicone elastomer facial prostheses. The glass-fiber reinforced framework makes it possible to make the margin of the prosthesis very tight, so that it will lean tightly against the skin even during facial expressions and jaw movements. The purpose of this study was to study how the compression of the glass-fiber reinforced framework would affect the microcirculation of the facial skin. Materials and methods. A face mask, with a compression pad corresponding to the outer margin of a glass fiber-reinforced composite framework beam of a facial prosthesis, was used to apply pressure on the facial skin of healthy volunteers. The skin blood flow during touch, light and moderate compression of the skin was measured by laser Doppler imaging technique. Results. None of the compressions had any marked effects on local skin blood flow. No significant differences between the blood flow of the compressed skin, compared to the baseline values, were found. Conclusions. The pressure applied to the skin by the tight margins of a facial prosthesis, fabricated with a framework of glass-fiber reinforced composite, does not remarkably alter the skin blood flow.     

Hierarchy of restorative space required for different types of dental implant prostheses

BackgroundManagement of the full and partially edentulous arch requires an understanding regarding the amount of vertical and horizontal restorative space that is needed for different types of dental implant prostheses. Failure to design a prosthetic construct without considering space issues can result in a rehabilitation with diminished stability, poor esthetics, and inadequate contours. Therefore, available restorative volume must be computed before initiating therapy to ensure proper prosthesis design.Types of Studies ReviewedThe authors searched the dental literature for articles that addressed space requirements for different types of dental implant prostheses and found a few on this subject.ResultsThe dental literature indicates there is a 3-dimensional hierarchy of restorative space necessary for different types of implant constructs. The minimum amount of vertical space required for implant prostheses is as follows: fixed screw-retained (implant level): 4 through 5 millimeters; fixed screw-retained (abutment level): 7.5 mm; fixed cement-retained: 7 through 8 mm; unsplinted overdenture: 7mm; bar overdenture: 11 mm; and fixed screw-retained hybrid: 15mm. These dimensions represent the minimal amount of vertical rehabilitative space that can accommodate the above implant prostheses. With respect to horizontal space, computations are needed to account for the discrepancy between an implant and tooth position.Conclusions and Practical ImplicationsRestorative spaces for each type of prostheses are restoration specific and should be considered during treatment planning to facilitate proper case selection and enhance patient satisfaction.     

Implant-Supported Facial Prostheses Provided by a Maxillofacial Unit in a U.K. Regional Hospital: Longevity and Patient Opinions

PURPOSE: The aim of this study was to acquire information on the types and longevity of implant-retained facial prostheses and the opinions of patients on several factors related to their prostheses. MATERIALS AND METHODS: A survey of 75 maxillofacial prosthetic patients currently under treatment and review at the Maxillofacial Unit, Morriston Regional Hospital was conducted through a 23-question postal questionnaire. These patients were selected as representative of a group of individuals receiving treatment or under review for the fabrication of maxillofacial prostheses. RESULTS: Of the prosthetic replacements, 83% were ear prostheses, 8% nose, 6% eye, and 2% combination prostheses. Of the 47 respondents, 8 (17%) reported that they were currently wearing their original prostheses. The remaining 39 (83%) respondents had all been provided with at least 1 replacement prosthesis. The mean lifetime of the prostheses was found to be 14 months (range: 4-36 months). The majority of replacement prostheses in this study were provided as a result of color fade or wear of the silicone material of the previous prosthesis. Individuals with no previous experience wearing a prosthesis had an unrealistic expectation of their prosthesis longevity, with a mean value of 17.8 months. In comparison, individuals with previous experience had reduced expectations, with a mean of 14.4 months. In terms of the patients' opinions of the overall quality of their prostheses, the results demonstrated that a large number of patients were satisfied. Thirty-five patients rated their prostheses as excellent and 9 as good. At 7-12 months, 4 patients rated their prostheses as excellent and 8 as good. At 13 months, 4 patients rated their prostheses as excellent and 5 as good. CONCLUSIONS: It is important that advice be given to patients on the expected average longevity of their prostheses, together with information on factors affecting the longevity (i.e., environmental staining, cosmetics, and cleaning regimes). In this study, 26% of the replacement prostheses were provided due to color fading of the original prosthesis. This highlights the need for continuing research in the development of materials used for the construction of facial prostheses with improved properties, and in particular, improved color stability.     

Using an Existing Orbital Prosthesis in the Construction of a New One

A procedure for fabrication of a new orbital prosthesis using an existing one and keeping its acceptable characteristics is described. The procedure saves time without depriving the patient of the existing prosthesis for a long period and can be applied in the remaking of other types of facial prostheses.     

A digital approach integrating facial scanning in a CAD-CAM workflow for complete-mouth implant-supported rehabilitation of patients with edentulism: A pilot clinical study

Statement of problem

Complete-mouth implant-supported rehabilitations are challenging because of the multiple surgical and prosthetic steps involved in clinical evaluations to assure passive prosthesis fit and optimal esthetic and functional outcomes. As a result, these rehabilitations are usually associated with substantial clinical time, patient discomfort, and high treatment cost.

Digital workflow for a dental prosthesis that considers lateral mandibular relation

Most digital prosthesis designs consider only the maximal intercuspal position (MIP) and not the lateral movement. During the computer-aided design and computer-aided manufacture (CAD-CAM) prosthesis delivery process, the clinician has to adjust the prosthesis to avoid occlusal interference during lateral excursion. The novel digital workflow described in this report can be divided into 2 steps. After obtaining interocclusal records for the MIP and the lateral excursion position, the crown CAD data were designed using a general digital workflow considering only the MIP. The previous crown CAD data were then adjusted in the lateral excursion state before manufacturing the prosthesis. This process using information for 2 occlusal positions means that the definitive prosthesis design reflects not only static occlusion but also lateral mandibular relation.     

Magnet-retained facial prosthesis combined with an implant-supported edentulous maxillary obturator: a case report

The prosthetic rehabilitation of maxillofacial defects is especially challenging when the patient is edentulous. Although dental implants are used to enhance the retention and stability of both facial and maxillary prostheses, combining facial and maxillary prostheses is extremely difficult. This article describes the prosthetic treatment of an edentulous patient with a large maxillary and facial defect. After placing dental implants in the remaining maxilla, a maxillary obturator prosthesis supported by a milled bar attachment was fabricated. The facial prosthesis was retained by a magnetic attachment to the maxillary obturator prosthesis. As the obturator prosthesis was supported securely by this sturdy attachment, the facial prosthesis was stable during mastication and facial movement. The patient reported improvement in prosthesis retention and stability. Both the masticatory and the speech functions of the patient improved.     

Simplified Technique for Orbital Prosthesis Fabrication: A Clinical Report

Loss of orbital content can cause functional impairment, disfigurement of the face, and psychological distress. Rehabilitation of an orbital defect is a complex task, and if reconstruction by plastic surgery is not possible or not desired by the patient, the defect can be rehabilitated by an orbital prosthesis. The prosthetic rehabilitation in such cases depends on the precisely retained, user‐friendly removable maxillofacial prosthesis. Many times, making an impression of the orbital area with an accurate record of surface details can be a difficult procedure. The critical areas are making a facial moulage, mold preparation, and attaching the retention device, particularly when eyeglass frames are used. This case focuses on these hindrance factors. A simple basket was used for the impression tray to obtain the facial moulage. A putty mold was used, and attachment of the prosthesis to a retention device was accomplished with positional distance. This method proves to be an economical and simple way of making an orbital prosthesis.