A systematic review of the computerized tools and digital techniques applied to fabricate nasal, auricular, orbital and ocular prostheses for facial defect rehabilitation

Cost-effective 3D scanning and printing technologies for outer ear reconstruction: current status

Current 3D scanning and printing technologies offer not only state-of-the-art developments in the field of medical imaging and bio-engineering, but also cost and time effective solutions for surgical reconstruction procedures. Besides tissue engineering, where living cells are used, bio-compatible polymers or synthetic resin can be applied. The combination of 3D handheld scanning devices or volumetric imaging, (open-source) image processing packages, and 3D printers form a complete workflow chain that is capable of effective rapid prototyping of outer ear replicas. This paper reviews current possibilities and latest use cases for 3D-scanning, data processing and printing of outer ear replicas with a focus on low-cost solutions for rehabilitation engineering.

Photogrammetry technology in implant dentistry: A systematic review

STATEMENT OF PROBLEM

Photogrammetry technology may be useful in implant dentistry, but a systematic review is lacking and is indicated before routine use in clinical practice.

PURPOSE

The purpose of this systematic review was to assess the role of the photogrammetry technology used in implant dentistry and determine its validity as an accurate tool with clinical applications.

MATERIAL AND METHODS

Four major databases, PubMed MEDLINE, Google Scholar, Scopus, and Web of Science, were selected to retrieve articles published from January 2011 to February 2021 based on custom criteria. The search was augmented by a manual search. After screening of the collected articles, data, including study design and setting, type of application, digitizer used, reference body, method of evaluation, and overall outcomes, were extracted.

RESULTS

Twenty articles were included based on the selection criteria. Most of the articles confirmed that the use of photogrammetry was promising as an implant coordinate transfer system. However, few articles showed its use for 3-dimensional scanning, which might require more development.

CONCLUSIONS

The initial reports of using photogrammetry technology considered this method as a valid and reliable clinical tool in implant dentistry. More studies to develop the photogrammetry technology and to assess the results with evidence-based research are recommended to enhance its application in different clinical situations.

Trueness and precision of skin surface reproduction in digital workflows for facial prosthesis fabrication

STATEMENT OF PROBLEM

How much skin surface details of facial prostheses can be transferred throughout the digital production chain has not been quantified.

PURPOSE

The purpose of this in vitro study was to quantify the amount of skin surface details transferred from the prosthesis virtual design through the prototype printing with various additive manufacturing (AM) methods to the definitive silicone prosthesis with an indirect mold-making approach.

MATERIAL AND METHODS

Twelve test blocks with embossed wrinkles of 0.05 to 0.8 mm and 12 test blocks with applied earlobe skin structures were printed with stereolithography (SLA), direct light processing (DLP), and PolyJet methods (n=4). DLP and SLA prototype specimens were duplicated in wax. All specimens were then transferred into medical-grade silicone. Rz values of the wrinkle test blocks and the root mean square error (RMSE) of the earlobe test blocks were evaluated by laser topography to determine the trueness and precision of each stage.

RESULTS

For the earlobe test blocks, the PolyJet method had superior trueness and precision of the final skin surface reproduction. The SLA method showed the poorest trueness, and the DLP method, the lowest precision. For the wrinkle test blocks, the PolyJet method had the best wrinkle profile reproduction level, followed by DLP and SLA.

CONCLUSIONS

The indirect mold-making approach of facial prostheses manufacturing may be associated with 7% of skin surface profile loss with SLA, up to 20% with DLP, and no detail loss with PolyJet.

IMproving facial PRosthesis construction with contactlESs Scanning and Digital workflow (IMPRESSeD): study protocol for a feasibility crossover randomised controlled trial of digital versus conventional manufacture of facial prostheses in patients with orbital or nasal facial defects

BACKGROUND

Facial prostheses can have a profound impact on patients' appearance, function and quality of life. There has been increasing interest in the digital manufacturing of facial prostheses which may offer many benefits to patients and healthcare services compared with conventional manufacturing processes. Most facial prosthesis research has adopted observational study designs with very few randomised controlled trials (RCTs) documented. There is a clear need for a well-designed RCT to compare the clinical and cost-effectiveness of digitally manufactured facial prostheses versus conventionally manufactured facial prostheses. This study protocol describes the planned conduct of a feasibility RCT which aims to address this knowledge gap and determine whether it is feasible to conduct a future definitive RCT.

METHODS

The IMPRESSeD study is a multi-centre, 2-arm, crossover, feasibility RCT with early health technology assessment and qualitative research. Up to 30 participants with acquired orbital or nasal defects will be recruited from the Maxillofacial Prosthetic Departments of participating NHS hospitals. All trial participants will receive 2 new facial prostheses manufactured using digital and conventional manufacturing methods. The order of receiving the facial prostheses will be allocated centrally using minimisation. The 2 prostheses will be made in tandem and marked with a colour label to mask the manufacturing method to the participants. Participants will be reviewed 4 weeks following the delivery of the first prosthesis and 4 weeks following the delivery of the second prosthesis. Primary feasibility outcomes include eligibility, recruitment, conversion, and attrition rates. Data will also be collected on patient preference, quality of life and resource use from the healthcare perspective. A qualitative sub-study will evaluate patients' perception, lived experience and preference of the different manufacturing methods.

DISCUSSION

There is uncertainty regarding the best method of manufacturing facial prostheses in terms of clinical effectiveness, cost-effectiveness and patient acceptability. There is a need for a well-designed RCT to compare digital and conventional manufacturing of facial prostheses to better inform clinical practice. The feasibility study will evaluate key parameters needed to design a definitive trial and will incorporate early health technology assessment and a qualitative sub-study to identify the potential benefits of further research.

TRIAL REGISTRATION

ISRCTN ISRCTN10516986). Prospectively registered on 08 June 2021,  https://www.isrctn.com/ISRCTN10516986 .

Digital database for nasal prosthesis design with a 3D morphable face model approach

Designing nasal prostheses can be challenging because of the unpaired nature of the facial feature, especially in patients lacking preoperative information. Various nose model databases have been developed as a helpful starting point for the computer-aided design of nasal prostheses, but these do not appear to be readily accessible. Therefore, an open-access digital database of nose models has been generated based on a 3-dimensional (3D) morphable face model approach. This article describes the generation of the database, highlights steps for designing a nasal prosthesis, and points readers to the database for future clinical application and research.

Three-dimensionally printed facial prosthesis with a silicone veneer technique: A clinical report

Digital technology has revolutionized the acquisition of patient data and the fabrication of prosthetic replacements for extraoral defects. This clinical report illustrates the use of a new technique which allows the digital creation of an acrylic resin framework which is then veneered with silicone to create an esthetic prosthesis in less time and with less patient discomfort.

A comparison of digital and conventional fabrication techniques for an esthetic maxillofacial prosthesis for the cheek and lip

Maxillofacial prostheses have traditionally been manufactured by pouring silicone into molds. However, the development of computer-aided design and computer-aided manufacturing (CAD-CAM) systems allows the virtual planning, design, and manufacture of maxillofacial prostheses through the direct 3-dimensional printing of silicone. This clinical report describes the digital workflow as an alternative to the conventional method of restoring a large midfacial defect in the right cheek and lip. In addition, the approaches were nonblinded evaluated in relation to outcomes and time efficiency, while marginal adaptation and esthetics, including patient satisfaction, were assessed for both prostheses fabricated. The digital prosthesis had acceptable esthetics and fit with improved patient satisfaction, especially in terms of efficiency, comfort, and speed of the digital workflow.

Use of 3-dimensional imaging and manufacturing for bilateral auricular prostheses: A case series of six patients with congenital auricular defects

The prosthetic reconstruction of unilateral ear deformity is a straightforward procedure which relies on copying the details, position, and symmetry of the existing contralateral ear. However, reconstructing bilaterally missing ears is challenging. The use of 3-dimensional (3D) technology in the prosthetic reconstruction of the bilaterally missing ears of 6 patients is described. The deformity site was created directly by segmenting the patient's digital scan or indirectly via a desktop scanner. Adequate bone quantity and quality for implant retention and optimal implant locations were also identified virtually. The use of 3D technologies has made it more straightforward to accomplish ear symmetry, as well as to validate the orientation and location of the ears reliably with the minimum subjectivity. The printed ears were matched in shape, surface texture, and anatomy. The skin color was straightforward to record and store so that it could be reproduced at a future time. Overall, the digital manufacture of the ears was controlled, consistent, and reproducible.

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.

Effect of cut-out rescan procedures on the accuracy of an intraoral scanner used for digitizing an ear model: An in vitro study

PURPOSE

The purpose of this study was to evaluate the impact of the rescanning of mesh holes of different diameters on the accuracy of an intraoral scanner (IOS) used to digitize an ear model.

MATERIALS AND METHODS

An ear model was digitized using an intraoral scanner (Medit i500) to obtain a reference mesh. A baseline experimental scan was created by editing a duplicate of the reference mesh using the cut-out tool of the IOS software. Three equal groups were created based on the diameter of the cut-out areas: 2-mm (G1), 5mm (G2), and 8-mm (G3) (n = 15). The cut-out areas were rescanned and a total of 45 digital files were exported. The discrepancy between the reference and the experimental digital scans was measured using the root mean square calculation (RMS). The data were analyzed by a Kruskal-Wallis test followed by a post hoc Dunn's test with Bonferroni correction.

RESULTS

The trueness values ranged from 19.53 to 27.13 μm. There were significant differences in the RMS error values among the groups tested (p<.001) and post hoc multiple comparisons showed significant differences between the G1 and G2 groups (p = .04), G1 and G3 groups (p<.001), and G2 and G3 groups (p = .004). Overall, the precision values ranged from 4.93 to 7.73 μm and significant differences in the RMS values were only found between the G1 and G2 groups (p = .014).

CONCLUSIONS

Mesh hole rescanning affected the scanning accuracy (trueness and precision) of the IOS tested. The larger the diameter of the mesh holes, the less the trueness of the IOS tested. The precision values seemed to be less affected compared with the trueness by the cut-out and rescanning procedures. This article is protected by copyright. All rights reserved.

Digital workflow for auricular prosthesis fabrication with a negative mold

A prosthesis for a patient with a complete auricle defect can be fabricated with computer-aided design and computer-aided manufacturing, significantly reducing the number of patient visits and improving the efficiency of the production process. This technique provides a digital workflow for designing virtual patterns and negative molds for an auricular prosthesis.

Color translation from monoscopic photogrammetry +ID Methodology into a Polyjet final 3D printed facial prosthesis

Background: The artistic techniques necessary to fabricate facial prostheses mainly depend on individual skill and are not a resource easily reproduced. Digital technology has contributed to improved outcomes, often combining analog and new digital techniques in the same workflow. Methods: This article aims to present an innovative workflow to produce a final colored 3D printed and facial prosthesis by UV-map color translation into colored resin 3D printing. A modified +ID Methodology was used to obtain 3D models with the calibrated 3D printable patient's skin color. No hands-on physical molding, manual sculpture, or intrinsic silicone coloration was used. Results: The outcome resulted in acceptable aesthetics, adaptation, and an approximate color match after extrinsic coloration. The patient reported good comfort and acceptance. Conclusions: A direct resin 3D printed prosthesis may be a viable alternative, especially for rapid delivery as an immediate prosthesis or an option when there is no experienced anaplastogist to manufacture a conventional prosthesis.

Effectiveness of digital data acquisition technologies in the fabrication of maxillofacial prostheses - A systematic review

Objective

The systematic review was designed to review and analyze the outcomes of various digital data acquisition technologies used for treatment planning in the prosthetic rehabilitation of maxillofacial defects.

Methods

The review protocol was registered in PROSPERO data with registration number: CRD42020188415. The PICOS inclusion criteria was employed in the systematic review. An electronic search (PubMed, databases) yielded twenty-eight eligible case reports. The qualitative methodological assessment was done according to an article that provided criteria for special considerations in evaluating case reports. It consisted of four questions, each carrying grading of 0, 1, and 2. During the full-text screening, the reviewers shortlisted six outcomes (time, aesthetics, cost, dimensional accuracy, patient satisfaction, and fabrication process) and graded (0, 1, 3) according to the outcomes they met.

Results

The majority of the included case reports used LASER scanners. Auricular and orbital defects were the highest reported cases. In nasal and orbital defects, the mean outcome of the shorter time required for the fabrication was the highest. In auricular prostheses, the mean outcome of dimensional accuracy was highest. In facial prostheses, aesthetics, dimensional accuracy, and patient satisfaction had the highest mean outcome whereas, in obturators, the shorter time required, dimensional accuracy, and patient satisfaction had the highest mean outcome. A total of 18 studies were graded as highly significant studies according to the methodological qualitative assessment.

Conclusion

LASER scanning systems in nasal prostheses, LASER scanners and combination of CT scan and digital photography in auricular prostheses, digital photography and stereophotogrammetry in case of large facial defects and combination of MRI and CT scan for obturators appeared to be a superior method of digital data acquisition.

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.

Outcome measures in facial prosthesis research: A systematic review

STATEMENT OF PROBLEM

Facial prosthesis research uses a wide variety of outcome measures, which results in challenges when comparing the effectiveness of interventions among studies. Consensus is lacking regarding the most appropriate and meaningful outcome measures to use in facial prosthesis research to capture important perspectives.

PURPOSE

The purpose of the systematic review was to identify and synthesize outcome measures used in facial prosthesis research.

MATERIAL AND METHODS

Electronic searches were performed in 11 databases (including nonpeer-reviewed literature). The citations were searched, and expert societies were contacted to identify additional studies. Inclusion criteria comprised studies of participants with facial defects who required or had received prosthetic rehabilitation with an external facial prosthesis. Exclusion criteria comprised participants with ocular prostheses, case reports, case series with fewer than 5 participants, laboratory-based studies, and studies published before 1980. Study selection was performed independently by 2 reviewers. Discrepancies were resolved through discussion or by a third reviewer. Outcome measures were synthesized with a categorization approach based on the perspective, theme, and subtheme of the outcome measures. Quality assessment was performed with an appraisal tool that enabled evaluation of studies with diverse designs.

RESULTS

Database searching identified 13 058 records, and 7406 remained after duplications were removed. After initial screening, 189 potentially relevant records remained, and 186 full texts were located (98% retrieval rate). After full-text screening, 124 records were excluded. Citation searches and contact with expert societies identified 4 further records. In total, 69 articles (grouped into 65 studies) were included. Studies were categorized as per the perspective of their outcome measures, with the following findings: patient-reported (74% of studies), clinical indicators (34%), clinician-reported (8%), multiple viewpoints (6%), and independent observer-reported (3%). Patient-reported outcome measures included tools to assess satisfaction, quality of life, and psychologic health. Variability in the choice of outcome measures was evident among the studies, with many self-designed, unvalidated, condition-specific questionnaires reported. A greater number of outcome measure themes emerged over time; themes such as service delivery and health state utility have recently been evaluated.

CONCLUSIONS

Over the past 40 years, facial prosthesis research has focused on patient-reported outcome measures. Outcome measures relating to other perspectives have been used less frequently, although new themes appear to be emerging in the literature. Future research should use outcome measures with appropriate measurement properties for use with facial prosthetics.

Digital workflow and virtual validation of a 3D-printed definitive hollow obturator for a large palatal defect

This clinical report describes how a hollow obturator prosthesis was designed and fabricated for an 82-year-old partially edentulous patient with a large palatal defect. Computer-aided design (CAD) was used to design, articulate, and align the mandibular denture with the obturator prosthesis. The prosthesis was printed, adjusted chairside, rescanned, and made hollow by using a CAD software program. The prosthesis was printed in resin with a dental 3D printer. Quantitative evaluations of clinical (prosthesis dimensions, rest, and occlusal vertical dimensions) and virtual (surface area, volume, weight, interpoint mismatches, spatial overlap) parameters found that the 3D-printed prosthesis required an additional 5% chairside modification. The greatest differences in volume (24.7% less) and weight (22.2% less) were observed when the modified obturator bulb was made hollow via CAD. Hollowing the bulb, therefore, reduced the spatial overlap in volume by 16.8%.

Capturing patient anatomy for designing and manufacturing personalized prostheses

Prostheses play a critical role in healthcare provision for many patients and encompass aesthetic facial prostheses, prosthetic limbs and prosthetic joints, bones, and other implantable medical devices in musculoskeletal surgery. An increasingly important component in cutting-edge healthcare treatments is the ability to accurately capture patient anatomy in order to guide the manufacture of personalized prostheses. This article examines methods for capturing patient anatomy and discusses the degrees of personalization in medical manufacturing alongside a summary of current trends in scanning technology with a focus on identifying workflows for incorporating personalization into patient-specific products. Over the next decade, with increased harmonization of both personalization and automated prosthetic manufacturing will be the realization of improved patient compliance, satisfaction, and clinical outcomes.

Clinical Applications of Intraoral Scanning in Removable Prosthodontics: A Literature Review

PURPOSE

This review aimed to identify the reported intraoral scanning applications in fabricating different types of removable prostheses in the field of prosthodontics.

METHODS

A comprehensive electronic search was performed using the PubMed and MEDLINE databases. This review included in vitro studies and clinical reports published between January 2013 and March 2021. The main keywords were as follows: intraoral scanning, digital impression, computerized digital impression, removable prosthesis, chairside computer-aided design/computer-assisted manufacturing, digital complete denture, digital immediate complete denture, digital interim complete denture, digital removable partial denture, digital removable overdenture, digital obturator, digital occlusal splints, and digital maxillofacial prostheses.

RESULTS

In total, 33 papers (22 clinical reports, 8 papers focused on dental techniques, and 3 clinical studies) were included in the final analysis.

CONCLUSIONS

The efficiency of using intraoral scanning in the field of removable prosthodontics was documented. However, there is a need for more clinical studies to identify intraoral scanning-usage protocols and to yield reliable and valid data.

Development and virtual validation of a novel digital workflow to rehabilitate palatal defects by using smartphone-integrated stereophotogrammetry (SPINS)

Palatal defects are rehabilitated by fabricating maxillofacial prostheses called obturators. The treatment incorporates taking deviously unpredictable impressions to facsimile the palatal defects into plaster casts for obturator fabrication in the dental laboratory. The casts are then digitally stored using expensive hardware to prevent physical damage or data loss and, when required, future obturators are digitally designed, and 3D printed. Our objective was to construct and validate an economic in-house smartphone-integrated stereophotogrammetry (SPINS) 3D scanner and to evaluate its accuracy in designing prosthetics using open source/free (OS/F) digital pipeline. Palatal defect models were scanned using SPINS and its accuracy was compared against the standard laser scanner for virtual area and volumetric parameters. SPINS derived 3D models were then used to design obturators by using (OS/F) software. The resultant obturators were virtually compared against standard medical software designs. There were no significant differences in any of the virtual parameters when evaluating the accuracy of both SPINS, as well as OS/F derived obturators. However, limitations in the design process resulted in minimal dissimilarities. With further improvements, SPINS based prosthetic rehabilitation could create a viable, low cost method for rural and developing health services to embrace maxillofacial record keeping and digitised prosthetic rehabilitation.

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.

Optimization of Prosthodontic Computer-Aided Designed Models: A Virtual Evaluation of Mesh Quality Reduction Using Open Source Software

PURPOSE

Mesh optimization reduces the texture quality of 3D models in order to reduce storage file size and computational load on a personal computer. This study aims to explore mesh optimization using open source (free) software in the context of prosthodontic application.

MATERIALS AND METHODS

An auricular prosthesis, a complete denture, and anterior and posterior crowns were constructed using conventional methods and laser scanned to create computerized 3D meshes. The meshes were optimized independently by four computer-aided design software (Meshmixer, Meshlab, Blender, and SculptGL) to 100%, 90%, 75%, 50%, and 25% levels of original file size. Upon optimization, the following parameters were virtually evaluated and compared; mesh vertices, file size, mesh surface area (SA), mesh volume (V), interpoint discrepancies (geometric similarity based on virtual point overlapping), and spatial similarity (volumetric similarity based on shape overlapping). The influence of software and optimization on surface area and volume of each prosthesis was evaluated independently using multiple linear regression.

RESULTS

There were clear observable differences in vertices, file size, surface area, and volume. The choice of software significantly influenced the overall virtual parameters of auricular prosthesis [SA: F(4,15) = 12.93, R² = 0.67, p < 0.001. V: F(4,15) = 9.33, R² = 0.64, p < 0.001] and complete denture [SA: F(4,15) = 10.81, R² = 0.67, p < 0.001. V: F(4,15) = 3.50, R² = 0.34, p = 0.030] across optimization levels. Interpoint discrepancies were however limited to <0.1mm and volumetric similarity was >97%.

CONCLUSION

Open-source mesh optimization of smaller dental prostheses in this study produced minimal loss of geometric and volumetric details. SculptGL models were most influenced by the amount of optimization performed.

Automated Noncontact Facial Topography Mapping, 3-Dimensional Printing, and Silicone Casting of Orbital Prosthesis

PURPOSE

A proof-of-concept workflow study for the fabrication of custom orbital exenteration prostheses via automated noncontact scanning, 3D printing, and silicone casting.

DESIGN

Noncomparative, interventional case series.

METHODS

Setting: Single-center institutional study. StudyPopulation: Three patients who have discontinued wearing of the ocularist-made exenteration prosthesis due to altered fit, discoloration, or material degradation. InterventionProcedure: A digital representation of the exenteration socket and contralateral periocular region was captured through noncontact facial topography mapping. Digital construction of the anterior prosthesis surface was based on the mirrored image of the contralateral side, and the posterior surface contour was based on orbital cavity geometry. The anterior and posterior surface details were digitally merged. A 2-piece mold was designed and produced in a 3D printer. Colorimetry was used to create a custom blend of pigments for incorporation into the Shore 40 silicone elastomer to generate a prosthesis that approximates the patient's skin tone. MainOutcomeMeasures: Prosthesis symmetry, skin tone match, comfort of wear, and appearance.

RESULTS

The first copy of every 3D-printed orbital prosthesis using this fabrication workflow produced good symmetry, color match, and prosthesis fit. In one case, the recontoured second copy with improved prosthesis edge-to-skin interface was made without the patient present.

CONCLUSION

A noncontact 3D scanning, computer-aided design, 3D printing, and silicone casting for fabrication of orbital prosthesis was developed and validated. This production workflow has the potential to provide an efficient, standardized, reproducible exenteration prosthesis and to overcome the principal barriers to an affordable custom prosthesis worldwide: access and cost.

Evaluation of the Differences Between Conventional and Digitally Developed Models Used for Prosthetic Rehabilitation in a Case of Untreated Palatal Cleft

OBJECTIVE

The virtual cone beam computed tomography-derived 3-dimensional model was compared with the scanned conventional model used in the fabrication of a palatal obturator for a patient with a large palatal defect.

DESIGN

A digitally derived 3-dimensional maxillary model incorporating the palatal defect was generated from the patient's existing cone beam computerized tomography data and compared with the scanned cast from the conventional impression for linear dimensions, area, and volume. The digitally derived cast was 3-dimensionally printed and the obturator fabricated using traditional techniques. Similarly, an obturator was fabricated from the conventional cast and the fit of both final obturator bulbs were compared in vivo.

RESULTS

The digitally derived model produced more accurate volumes and surface areas within the defect. The defect margins and peripheries were overestimated which was reflected clinically.

CONCLUSION

The digitally derived model provided advantages in the fabrication of the palatal obturator; however, further clinical research is required to refine consistency.

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

STATEMENT OF PROBLEM

One 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.

PURPOSE

The 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 METHODS

Scan 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.

RESULTS

A 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.

CONCLUSIONS

An 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.

Temperature Compensation Method for Mechanical Base of 3D-Structured Light Scanners

The effect of temperature on three-dimensional (3D) structured light scanners is a very complex issue that, under some conditions, can lead to significant deterioration of performed measurements. In this paper, we present the results of several studies concerning the effect of temperature on the mechanical base of 3D-structured light scanners. We also propose a software compensation method suitable for implementation in any existing scanner. The most significant advantage of the described method is the fact that it does not require any specialized artifact or any additional equipment, nor access to the thermal chamber. It uses a simulation of mechanical base thermal deformations and a virtual 3D measurement environment that allows for conducting virtual measurements. The results from the verification experiments show that the developed method can extend the range of temperatures in which 3D-structured light scanners can perform valid measurements by more than six-fold.