No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Accuracy of capturing oncology nasal, orbital, and auricular defects with extra- and intraoral optical scanners and smartphone: An in vitro study
Abstract
Objectives: This in vitro study compares the scanning accuracy of various stationary and portable as well as extra- and intraoral devices for capturing oncology defects.
Methods: a one 3D-printed model of nasal, orbital, and auricular defects, as well as of 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 heat 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 type 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 an 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 a universal tool for the digitization of oncology 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.
... It utilizes a so-called structure-from-motion algorithm to reconstruct the three-dimensional camera position of each photograph [9]. Intraoral scanners have also been described in the context of digitizing parts of the face [10]. Optical scanners using visible light to capture surfaces can be influenced by ambient light, as it disturbs the pattern projected by the scanners. ...
... Furthermore, the predictability of a treatment outcome can be supported by integrating facial information into simulations [8]. The data can also be used in the process of creating facial prostheses [10]. However, to accomplish all these tasks, they need to provide a certain accuracy. ...
... To examine the accuracy of face scanners, some studies have compared them with previously established face scanners, like the 3dMDface or the Vectra H1 [8,13,14]. Others have employed extraoral scanners, like the D2000, the Faro Design Sca-nArm 2.0, or the Classic iCAT, to create reference scans [10,15,16]. Some studies have also employed original model files as a reference, used to 3D-print a head model for testing [6,7]. ...
Background
Face scanners provide a viable method for capturing a patient’s face geometry. To optimize their accuracy, influencing factors, like the ambient light, need to be examined.
Methods
A human head model with eight pins attached to its surface was used to investigate the accuracy of four face scanning methods (Face Hunter, iPad, Medit i700, single camera photogrammetry) under three illumination levels (500 lx, 5000 lx, 20 000 lx). An industrial CT scan was used as reference. Two alignment-areas – full face (AL-FF) and spheres (AL-KG) and two investigation areas – center face (UB-CF) and full face (UB-FF), were used during the examination. The root-mean-square-error (RMSE) was employed as a measure. Separated by trueness and precision, a one-way ANOVA was performed with post hoc Games-Howell tests for each scanning method.
Results
All scanners showed significant differences between the illumination levels. For most test groups, the Face Hunter acquired its lowest RMSE values under 500 lx. The same can be said for the Medit i700, even though for trueness, differences to 5000 lx were random. Single camera photogrammetry performed better at higher illumination levels, but only random differences between 5000 lx and 20 000 lx were seen. For the iPad, different results for optimal illumination were found regarding trueness and precision, as well as the investigation areas. All accuracy results were labelled as highly reliable, except for the iPad´s trueness results.
Conclusion
Scanner-dependent influence of ambient light was shown in this in-vitro study. Face Hunter and Medit i700 performed better under a darker illumination of 500 lx, whereas single camera photogrammetry needed brighter lighting. For the iPad no tested lighting situation showed clear advantages.
... The study tested precision, and not trueness, because the true form of the specimens would be difficult to obtain in such high detail. However, the fact that precision was high in all different tested scenarios (various anatomical form configurations in different surface conditions), along with the established trueness of the scanner in various other models [16,[18][19][20][21], strongly indicates that high accuracy would also be evident in the skeletal surfaces tested here. The high accuracy of this scanner has already been exhibited in previous studies testing different surfaces such as teeth [16], ...
... The study tested precision, and not trueness, because the true form of the specimens would be difficult to obtain in such high detail. However, the fact that precision was high in all different tested scenarios (various anatomical form configurations in different surface conditions), along with the established trueness of the scanner in various other models [16,[18][19][20][21], strongly indicates that high accuracy would also be evident in the skeletal surfaces tested here. The high accuracy of this scanner has already been exhibited in previous studies testing different surfaces such as teeth [16], human skin [18,19], human fingerprints depicted in plastic materials [20], or even in difficult-to-scan objects [21]. ...
... However, the fact that precision was high in all different tested scenarios (various anatomical form configurations in different surface conditions), along with the established trueness of the scanner in various other models [16,[18][19][20][21], strongly indicates that high accuracy would also be evident in the skeletal surfaces tested here. The high accuracy of this scanner has already been exhibited in previous studies testing different surfaces such as teeth [16], human skin [18,19], human fingerprints depicted in plastic materials [20], or even in difficult-to-scan objects [21]. So far, the scanner has mostly been used to scan smaller objects or limited surfaces. ...
Three-dimensional surface scans of skeletal structures have various clinical and research applications in medicine, anthropology, and other relevant fields. The aim of this study was to test the precision of a widely used hand-held surface scanner and the associated software’s 3D model generation-error in both dry and wet skeletal surfaces. Ten human dry skulls and ten mandibles (dry and wet conditions) were scanned twice with an industrial scanner (Artec Space Spider) by one operator. Following a best-fit superimposition of corresponding surface model pairs, the mean absolute distance (MAD) between them was calculated on ten anatomical regions on the skulls and six on the mandibles. The software’s 3D model generation process was repeated for the same scan of four dry skulls and four mandibles (wet and dry conditions), and the results were compared in a similar manner. The median scanner precision was 31 μm for the skulls and 25 μm for the mandibles in dry conditions, whereas in wet conditions it was slightly lower at 40 μm for the mandibles. The 3D model generation-error was negligible (range: 5–10 μm). The Artec Space Spider scanner exhibits very high precision in the scanning of dry and wet skeletal surfaces.
... Besides care for patients with cleft lip and palate, laboratory studies have illustrated that IOSs can digitize facial defects to clinically acceptable levels, potentially rivaling the scanning accuracy of extraoral optical systems (Dohiem et al. 2022;Unkovskiy et al. 2022). Considering that IOSs are more accessible and less expensive that extraoral facial scanners, employing IOSs emerges as a promising avenue for innovative digital solutions and cost reductions in maxillofacial prosthetics. ...
... Considering that IOSs are more accessible and less expensive that extraoral facial scanners, employing IOSs emerges as a promising avenue for innovative digital solutions and cost reductions in maxillofacial prosthetics. However, it is crucial to note that the capabilities of IOSs have inherent limitations: certain defects, such as orbital defects, surpass their scope of applicability (Unkovskiy et al. 2022). ...
Intraoral scanners (IOSs) have emerged as a cornerstone technology in digital dentistry. This article examines the recent advancements and multifaceted applications of IOSs, highlighting their benefits in patient care and addressing their current limitations. The IOS market has seen a competitive surge. Modern IOSs, featuring continuous image capture and advanced software for seamless image stitching, have made the scanning process more efficient. Patient comfort with IOS procedures is favorable, mitigating the discomfort associated with conventional impression taking. There has been a shift toward open data interfaces, notably enhancing interoperability. However, the integration of IOSs into large dental institutions is slow, facing challenges such as compatibility with existing health record systems and extensive data storage management. IOSs now extend beyond their use in computer-aided design and manufacturing, with software solutions transforming them into platforms for diagnostics, patient communication, and treatment planning. Several IOSs are equipped with tools for caries detection, employing fluorescence technologies or near-infrared imaging to identify carious lesions. IOSs facilitate quantitative monitoring of tooth wear and soft tissue dimensions. For precise tooth segmentation in intraoral scans, essential for orthodontic applications, developers are leveraging innovative deep neural network-based approaches. The clinical performance of restorations fabricated based on intraoral scans has proven to be comparable to those obtained using conventional impressions, substantiating the reliability of IOSs in restorative dentistry. In oral and maxillofacial surgery, IOSs enhance airway safety during impression taking and aid in treating conditions such as cleft lip and palate, among other congenital craniofacial disorders, across diverse age groups. While IOSs have improved various aspects of dental care, ongoing enhancements in usability, diagnostic accuracy, and image segmentation are crucial to exploit the potential of this technology in optimizing patient care.
... [19][20][21][22][23][24][25][26] Intraoral scanners have been suggested as a suitable method for acquiring digital data for maxillofacial prostheses, generating a 3D replica with a detailed information of the facial anatomy. [27][28][29][30] Jablonski et al 31,32 evaluated laser scanning accuracy and the use of structured light scanning in conjunction with stereophotogrammetry, and Aswehlee et al 33 compared 3 different stereophotogrammetry systems with laser scanning. However, only fixed scanning equipment was used in these investigations. ...
... The use of intraoral scanners for direct facial scanning and its impact on the construction process of facial prostheses are of developing interest. 27,29,30 However, the clinical accuracy of the maxillofacial imaging technique using intraoral scanners has not been evaluated sufficiently. The current observational study evaluated the use of different intraoral scanners for the extraoral maxillofacial digitization of an intact ear and visually assessed the clinical outcome of the 3D generated ear casts. ...
... However, the authors attributed the error to the automatic reconstruction function of the software, a function we did not use. The Artec Space Spider gave one of the best validity measures compared to the Primescan, Trios, Pritiface and iPhone systems when used to scan nasal, orbital and auricular models that were manufactured using stereolithography 12 . The Artec Space Spider's results were found to be most valid compared to Artec Eva, Vectra H1, Bellus and SNAP after scanning plaster statues with balls attached; the linear measurements were used for comparison purposes 13 . ...
Several new systems for three-dimensional (3D) surface imaging of the face have become available to assess changes following orthognathic or facial surgery. Before they can be implemented in practice, their reliability and validity must be established. Our aim, therefore, was to study the intra- and inter-system reliability and validity of 3dMD (stereophotogrammetry), Artec Eva and Artec Space Spider (both structured light scanners). Intra- and inter-system reliability, expressed in root mean square distance, was determined by scanning a mannequin’s head and the faces of healthy volunteers multiple times. Validity was determined by comparing the linear measurements of the scans with the known distances of a 3D printed model. Post-processing errors were also calculated. Intra-system reliability after scanning the mannequin’s head was best with the Artec Space Spider (0.04 mm Spider; 0.07 mm 3dMD; 0.08 mm Eva). The least difference in inter-system reliability after scanning the mannequin’s head was between the Artec Space Spider and Artec Eva. The best intra-system reliability after scanning human subjects was with the Artec Space Spider (0.15 mm Spider; 0.20 mm Eva; 0.23 mm 3dMD). The least difference in inter-system reliability after scanning human subjects was between the Artec Eva and Artec Space Spider. The most accurate linear measurement validity occurred with the Artec Space Spider. The post-processing error was 0.01 mm for all the systems. The Artec Space Spider is the most reliable and valid scanning system.
... The described technique uses the geometry of the nose as a reference to align intraoral scans to the facial scan. The nose was chosen as a reference because it represents common and stable landmarks, 14,16 reliably scanned by IOSs, 18 and provides detectable geometry to align both intraoral and facial scans. 14 For patient comfort, the intraoral scan was performed in two steps: a detailed scan of the full maxillary arch including the palate, and a scan of the entire nose including only the occlusion surfaces of the maxillary arch. ...
Advanced digital technologies have rabidly been integrated into prosthodontics to improve the digital workflow for prosthetic rehabilitation. The integration of 3D datasets acquired from various imaging sources such as intraoral scanners and facial optical scanners allows the creation of virtual patients to perform presurgical simulation and prosthetic rehabilitation. The presented technique introduced a straightforward protocol for aligning intraoral scans (Trios 4, 3Shape) to optical face scans (Face Hunter, Zirkonzahn GmbH) using a global bestfit algorithm of 3D evaluation software (GOM Inspect). Nasal geometry data was used as a matching reference to produce virtual dental patients. This integration protocol proved that the intraoral scanner (Trios 4, 3Shape) was used not only to scan dental arches but also used effectively to scan the nose. These scans along with professional facial scans can be successfully aligned to produce virtual dental patients. Because only one single fully-dentate patient case with an alignment deviation of 243.6 μm was used, further research to evaluate the accuracy of this protocol is needed.
... The described technique uses the geometry of the nose as a reference to align intraoral scans to the facial scan. The nose was chosen as a reference because it represents common and stable landmarks, 14,16 reliably scanned by IOSs, 18 and provides detectable geometry to align both intraoral and facial scans. 14 For patient comfort, the intraoral scan was performed in two steps: a detailed scan of the full maxillary arch including the palate, and a scan of the entire nose including only the occlusion surfaces of the maxillary arch. ...
Advanced digital technologies have rabidly been integrated into prosthodontics to improve the digital workflow for prosthetic rehabilitation. The integration of 3D datasets acquired from various imaging sources such as intraoral scanners and facial optical scanners allows the creation of virtual patients to perform presurgical simulation and prosthetic rehabilitation. The presented technique introduced a straightforward protocol for aligning intraoral scans (Trios 4, 3Shape) to optical face scans (Face Hunter, Zirkonzahn GmbH) using a global bestfit algorithm of 3D evaluation software (GOM Inspect). Nasal geometry data was used as a matching reference to produce virtual dental patients. This integration protocol proved that the intraoral scanner (Trios 4, 3Shape) was used not only to scan dental arches but also used effectively to scan the nose. These scans along with professional facial scans can be successfully aligned to produce virtual dental patients. Because only one single fully-dentate patient case with an alignment deviation of 243.6 μm was used, further research to evaluate the accuracy of this protocol is needed.
... These photographs are then mathematically processed to generate a 3D object by identifying similar and repeated points in the photographs and linking them through precise calculations to a defined 3D coordinate. 9,[13][14][15] The reliability of photogrammetry has been reported in diverse applications, including evaluating dental implant positions and creating precise impressions for complete arch immediate prostheses. 14,16 The aim of this study was to investigate the accuracy of photogrammetry using 3 different computer software programs and 1 smartphone Android application for rendering digital 3D casts. ...
... However, the authors attributed the error to the automatic reconstruction function of the software, a function we did not use. Artec Space Spider showed one of the best validity measures when compared to Primescan, Trios, Pritiface and iPhone when used to scan nasal, orbital and auricular models that were manufactured using stereolithography 11 . Artec Space Spider was found to be most valid compared to Artec Eva, Vectra H1, Bellus and SNAP when used to scan plaster statues with balls attached of which linear measurements were used for comparison 12 . ...
Introduction
Several new systems of three-dimensional (3D) surface imaging of the face have become available to assess changes following orthognathic or facial surgery. Before they can be implemented into practice their reliability and validity must be established. Our aim was therefore to study 3dMD (stereophotogrammetry), Artec Eva and Artec Space Spider (both structured light scanners) regarding intra- and inter-system reliability and validity.
Material and Methods
Intra- and inter-system reliability expressed in root mean square (RMS) distance was determined by scanning multiple times a mannequin’s head and faces of healthy volunteers. Validity was determined by comparing linear measurements of scans with known distances of a 3D printed model. Post-processing errors were calculated.
Results
Intra-system reliability of mannequin’s head was best for the Artec Space Spider (0.04 mm Spider; 0.07 mm 3dMD; 0.08 mm Eva;). Inter-system reliability of the mannequin’s head showed least differences between Artec Space Spider and Artec Eva. Intra-system reliability of human subjects was best for the Artec Space Spider (0.15 mm Spider; 0.20 mm Eva; 0.23 mm 3dMD). Inter-system reliability of human subjects showed least differences between Artec Eva and Artec Space Spider. Validity of linear measurements was most accurate in the Artec Space Spider. Post-processing error was 0.01mm for all systems.
Conclusion
The Artec Space Spider was the most reliable and valid scanning system.
... 3D facial scanning will be undertaken using a structured light scanner (Artec Space Spider; Artec 3D) which will capture the participant's facial defect and surrounding facial features. Whilst a broad range of facial scanning techniques are available [19,36], structured light scanning has been shown to have good accuracy and repeatability at digitising facial defects in an in vitro context [37][38][39]. CAD will involve the use of a 3D Morphable Face Model (Leeds Face Model; University of Leeds) to help design the facial prosthesis in a statistically meaningful way based upon the participant's other facial features [40][41][42]. There will be opportunity to further modify the design using landmark fitting techniques where participants share facial photographs from before their cancer treatment or wearing a previously successful prosthesis [43]. ...
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.
... This approach provides faster, cheaper, and more customized solutions and is widely documented in the literature [17][18][19]. The first step of the procedure is data acquisition: surface laser scanning, 3D photogrammetry, CT, and an MRI scan, which are standard methods mentioned in the scientific literature [6,[20][21][22][23]. For example, to manufacture an auricular prosthesis supported by craniofacial implants, the overlapping of CT and surface laser scan data ensures the best accuracy thanks to the combination of the skin surface and the bony skull data in a single STL file, which is useful to determine the position of the craniofacial implants in relation to the prosthesis [11]. ...
This case report aims to describe novel steps in the digital design/manufacturing of facial prostheses for cancer patients with wide inoperable residual defects, with a focus on a case of a mid-facial defect. A facial scanner was used to make an impression of the post-surgical residual defect and to digitalize it. The daughter’s face scan was used for reconstructing the missing anatomy. Using 3D printing technologies, try-in prototypes were produced in silicone material. The substructure was laser melted. The final prosthesis was relined directly onto the patient’s defect. The prosthesis resulted in a very low weight and a high elasticity of the external margins. The laser-melted substructure ensured the necessary rigidity with minimum thickness.
... The authors have previously validated a workflow to obtain 3D facial data by applying a mobile device and monoscopic photogrammetry, conducted experiments on healthy subjects, and reported its feasibility [7]. Similarly, several research groups have reported on the accuracy of digital impressions with mobile devices [10][11][12]. However, these are only evaluations on 3D data on a computer, and few accuracy evaluations on printed models fabricated using additive manufacturing have been performed. ...
Purpose: The purpose of this study was to perform an in vitro evaluation of digital impressions using a mobile device and monoscopic photogrammetry in cases of orbital defects with undercuts.
Methods: Three 10-mm-square cubes were attached to a diagnostic cast of a patient with a right orbital defect. Still images acquired with a mobile device were used to generate facial three-dimensional (3D) data. Two types of still images were used: one was a whole face image, and the other was a defect site-focused image. For comparison, an extraoral scanner was used to obtain facial 3D data. Five dental technicians fabricated 3D printed models using additive manufacturing and measured the distances between the measurement points using a digital caliper. The discrepancy between the distances measured on the diagnostic cast of the patient and the 3D printed model was calculated. Friedman test was used to analyze the discrepancy, and the Bonferroni test was used to verify the differences between the pairs.
Results: Statistical significance was found with respect to the type of 3D model fabrication method.
Conclusion: Within the limitations of this in vitro study, the results suggested that the workflow can be applied to digital impressions of the maxillofacial region.
... Smartphone technology has become part of our daily lives and requires no professionality or experience. It has been presented in orthodontic literature for different purposes, such as digital cephalometric analysis [10 , 11] , treatment monitoring systems [12] , and clinical 3D facial scanning [13][14][15] . Virtual facial models were Fig. 1. ...
Background:
The development of intraoral scanning technology has effectively enhanced the digital documentation of orthodontic dental casts. Albeit, the expense of this technology is the main limitation. The purpose of the present study was to assess the validity and reliability of virtual three-dimensional (3D) models of orthodontic dental casts, which were constructed using smartphone-based 3D photogrammetry.
Methods:
A smartphone was used to capture a set of two-dimensional images for 30 orthodontic dental casts. The captured images were processed to construct 3D virtual images using Agisoft and 3DF Zephyr software programs. To evaluate the accuracy of the virtual 3D models obtained by the two software programs, the virtual 3D models were compared with cone-beam computed tomography scans of the 30 dental casts. Colored maps were used to express the absolute distances between the points of each compared two surfaces; then, the means of the 100%, 95th, and 90th of the absolute distances were calculated. A Wilcoxon signed-rank test was applied to detect any significant differences.
Results:
The differences between the constructed 3D images and the cone-beam computed tomography scans were not statistically significant and were accepted clinically. The deviations were mostly in the interproximal areas and in the occlusal details (sharp cusps and deep pits and fissures).
Conclusions:
This study found that smartphone-based stereophotogrammetry is an accurate and reliable method for 3D modeling of orthodontic dental casts, with errors less than the accepted clinically detectable error of 0.5 mm. Smartphone photogrammetry succeeded in presenting occlusal details, but it was difficult to accurately reproduce interproximal areas.
Objective
To compare the reliability of different digitizing methods not only among themselves but also with direct measurements from facial plaster models of unoperated cleft babies.
Design
Single-center retrospective study.
Setting
The study consisted facial models of babies with unilateral (UCLP, n = 65) and bilateral (BCLP, n = 65) cleft lip and palate from the archives of the Department of Orthodontics, Marmara University, Istanbul, Turkey. Those models were digitized using Medit i600, iTero Element 2 (Align Technology), and E3 3Shape scanning devices. A digital caliper with a 0.03 precision (INSIZE Digital Caliper) was used for manual measurements on plaster models. 3Shape Ortho Analyzer software was used for digital measurements.
Results
All scanning methods were reliable and compatible with a rate of 90% or more compared to manual measurements. The E3 3Shape device showed the lowest deviations (UCLP, between 0.04 and 0.11 mm; BCLP, between 0.04 and 0.25 mm) from manual measurements. In the UCLP group, Medit i600 presented the highest deviation (0.15-0.58 mm) whereas Itero Element 2 showed the highest deviation in the BCLP group (0.16-0.46 mm). Although there were statistically significant differences in the deviations of digital measurements, the values were still within clinically acceptable limits.
Conclusion
Intraoral scanners were less reliable in topographic measurements, especially in cases with increased depth. Although the highest compatible results were found with E3 3Shape model scanner, iTero Element 2 and Medit i600 were promising and advisable for digitizing and archiving the plaster models of babies with cleft lip and palate.
Background: The use of digital tools and 3D molding has become very common in dentistry today. However, there are few studies on the possibility of using 3D imaging tools for molding maxillofacial defects. In this review study, we examine articles that have used digital molding tools instead of conventional methods for molding maxillofacial defects. Materials and Methods: In this study, all articles related to keywords of "3D imaging tools", "CT scans", "Maxillofacial Prosthesis" were collected and reviewed by searching PubMed and ISI Web of Science until 2024. Then, the materials were classified into the following topics: the use of intraoral scanners in molding for maxillofacial prostheses, the use of facial scanners in molding for maxillofacial prostheses, the use of CT scans in molding for maxillofacial prostheses, and the use of new digital methods in molding for ocular, nasal, ear prostheses, maxillary and mandibular obturators, soft palate defects, and nasoalveolar molding prostheses, and were examined in detail. Results: This study showed that depending on the type of defect, specific types of digital molding tools can be used to the greatest advantage. Intraoral scanners can be used in the construction of nasoalveolar moldings, obturators, cleft palate, and ear prostheses. Facial scanners have the highest accuracy for molding defects in the middle third of the face. Facial scanners are helpful in midface defects, and in the construction of ocular and nasal prostheses. The main use of CBCT molding is in molding the patient's palate for the design and construction of obturators. For mandibular molding, the use of intraoral scanners is much better than other methods. Moreover, even in cases where the patient has mild to moderate trismus after mandibulectomy, the use of intraoral scanners has acceptable accuracy.
This clinical report outlines the prosthetic restoration of a 92‐year‐old Caucasian patient who underwent a partial rhinectomy. Utilizing CAD‐CAM technology, scanning and design were accomplished digitally, and material jetting additive manufacturing was used to create a two‐piece mold for a partial nasal silicone prosthesis. An unprecedented challenge was observed involving cure inhibition when the silicone came into contact with the additively manufactured (AM) material, and multiple attempted strategies to remedy this situation were discussed. The report emphasizes the critical need for further research to optimize digital workflows in prosthetic facial rehabilitation.
Introduction
Facial scanning through smartphone scanning applications (SSA) is increasingly being used for medical applications as cost‐effective, chairside method. However, clinical validation is lacking. This review aims to address: (1) Which SSA could perform facial scanning? (2) Which SSA can be clinically used? (3) Which SSA have been reported and scientifically validated for medical applications?
Methods
Technical search for SSA designed for face or object scanning was conducted on Google, Apple App Store, and Google Play Store from August 2022 to December 2023. Literature search was performed on PubMed, Cochrane, EMBASE, MEDLINE, Scopus, IEEE Xplore, ACM Digital Library, Clinicaltrials.gov , ICTRP (WHO) and preprints up to 2023. Eligibility criteria included English‐written scientific articles incorporating at least one SSA for clinical purposes. SSA selection and data extraction were executed by one reviewer, validated by second, with third reviewer being consulted for discordances.
Results
Sixty‐three applications designed for three‐dimensional object scanning were retrieved, with 52 currently offering facial scanning capabilities. Fifty‐six scientific articles, comprising two case reports, 16 proof‐of‐concepts and 38 experimental studies were analysed. Thirteen applications (123D Catch, 3D Creator, Bellus 3D Dental Pro, Bellus 3D Face app, Bellus 3D Face Maker, Capture, Heges, Metascan, Polycam, Scandy Pro, Scaniverse, Tap tap tap and Trnio) were reported in literature for digital workflow integration, comparison or proof‐of‐concept studies.
Conclusion
Fifty‐two SSA can perform facial scanning currently and can be used clinically, offering cost‐effectiveness, portability and user‐friendliness. Although clinical validation is crucial, only 13 SSA were scientifically validated, underlying awareness of potential pitfalls and limitations.
Subject. Digital and conventional technologies for the making of ear epitheses. Objectives. To compare different methods of making ear epithesis according to the following criteria: timing, accuracy, ergonomics. Methodology. The study was carried out in Department of Propaedeutics and Prosthetics Technologies in Dentistry of DF, at the Moscow State University of Medial Dentistry named after A.I. Evdokimov. The students – volunteers' auricles were scanned with three different smartphone apps, two intraoral scanners and a facial scanner. Results. The 3D image obtained using a smartphone camera is comparable to models obtained using facial scanners, and the scanning process is simple and does not require special skills. Facial scanners are expensive equipment that require careful maintenance and certain skills for proper operation. Intraoral scanners are not initially designed for the production of facial epitheses; they partially capture the surface of interest, which requires operator intervention, which eliminates the accuracy of the manufactured structure. The conventional method is the least ergonomic, labor-intensive and requires professional competencies and skills in modeling the complex anatomy of epitheses. Conclusion. The most user friendly for making the ear epithesis was smartphone scanning, because in this case required minimal intervention by a operator for finishing the image of 3D copy healthy auricle of the patient.
This technique describes the use of a smartphone application for scanning an ear for 3-dimensional (3D) printing of an auricular prosthesis cast. The intact ear was scanned by using a smartphone and a 3D scan application (Polycam). The standard tessellation language (STL) file of the 3D data was used to produce a mirror image of the ear, which was sent to the 3D printing center where a resin cast was printed. This technique is harmless for the patient compared with radiological imaging methods, more comfortable, and cost-effective and is straightforward for the maxillofacial prosthodontist.
Statement of problem:
Making conventional facial impressions can be uncomfortable for the patient and complicated for the prosthodontist. Using facial scanners to digitize faces is an alternative approach. However, the initial costs of the equipment have prevented their widespread use in dental practice, and the accuracy of ear scanning is unclear.
Purpose:
The purpose of this in vitro study was to investigate the accuracy of a widely used intraoral scanner for digitizing an ear model.
Material and methods:
For reference, a silicone model of an ear was scanned with an industrial scanner. Then, the model was scanned 5 times with an intraoral scanner. Five conventional impressions of the model were made with a hydrocolloid impression material and poured with dental stone. The stone casts were then digitized with a desktop scanner. The data sets acquired with the 3 approaches were analyzed by using a 3-dimensional (3D) evaluation software program. Trueness and precision values were calculated for each approach. Linear mixed models with random intercepts were fitted to each sample to evaluate the effects of the impression method on mean deviations (α=.05).
Results:
Mean ±standard deviation trueness and precision values were 0.097 ±0.012 mm and 0.033 ±0.015 mm, respectively, for the digital scan, and 0.092 ±0.022 mm and 0.081 ±0.024 mm for the conventional impression, showing a significantly lower deviation in precision for the digital approach (P<.001).
Conclusions:
The feasibility of digitizing an ear efficiently by using the investigated intraoral scanner was demonstrated, and similar trueness and significantly better precision values were achieved than when using conventional impressions. These promising results suggest the need for clinical investigations.
Historically, facial prosthetics have successfully rehabilitated individuals with acquired or congenital anatomical deficiencies of the face. This history includes extensive efforts in research and development to explore best practices in materials, methods, and artisanal techniques. Presently, extraoral maxillofacial rehabilitation is managed by a multiprofessional team that has evolved with a broadened scope of knowledge, skills, and responsibility. This includes the mandatory integration of different professional specialists to cover the bio-psycho-social needs of the patient, systemic health and pathology surveillance, and advanced restorative techniques, which may include 3D technologies. In addition, recent digital workflows allow us to optimize this multidisciplinary integration and reduce the active time of both patients and clinicians, as well as improve the cost-efficiency of the care system, promoting its access to both patients and health systems. This paper discusses factors that affect extraoral maxillofacial rehabilitation's present and future opportunities from teamwork consolidation, techniques utilizing technology, and health systems opportunities.
Currently, there are several methods that can be used for modeling and measurihg of human face such as digital stereo photogrammetry, phase measuring profilometry and others. These methods were employed in medical applications for the modeling of human face soft tissue and measurement of anthropometric landmarks. Both data are required for the development of a craniofacial database in craniofacial reconstructive surgery. In this paper two laser scanners (i.e. three dimensional non-contact digitizers) were used to produce a three-dimensional model of human faces and measure anthropometric landmarks. The process comprises of four steps: scanning of human face, three-dimensional image registration, three-dimensional modeling of human face and measurement of anthropometric landmarks. The obtained anthropometric landmarks measurement then compared with the conventional measurement method using calipers. This study shows that the used of laser scanning system in modeling human face was found to be excellent and efficient
Statement of problem
The anatomic complexity of the ear challenges conventional maxillofacial prosthetic rehabilitation. The introduction of specialized scanning hardware integrated into computer-aided design and computer-aided manufacturing (CAD-CAM) workflows has mitigated these challenges. Currently, the scanning hardware required for digital data acquisition is expensive and not readily available for prosthodontists in developing regions.
Purpose
The purpose of this virtual analysis study was to compare the accuracy and precision of 3-dimensional (3D) ear models generated by scanning gypsum casts with a smartphone camera and a desktop laser scanner.
Material and methods
Six ear casts were fabricated from green dental gypsum and scanned with a laser scanner. The resultant 3D models were exported as standard tessellation language (STL) files. A stereophotogrammetry system was fabricated by using a motorized turntable and an automated microcontroller photograph capturing interface. A total of 48 images were captured from 2 angles on the arc (20 degrees and 40 degrees from the base of the turntable) with an image overlap of 15 degrees, controlled by a stepper motor. Ear 1 was placed on the turntable and captured 5 times with smartphone 1 and tested for precision. Then, ears 1 to 6 were scanned once with a laser scanner and with smartphones 1 and 2. The images were converted into 3D casts and compared for accuracy against their laser scanned counterparts for surface area, volume, interpoint mismatches, and spatial overlap. Acceptability thresholds were set at <0.5 mm for interpoint mismatches and >0.70 for spatial overlap.
Results
The test for smartphone precision in comparison with that of the laser scanner showed a difference in surface area of 774.22 ±295.27 mm² (6.9% less area) and in volume of 4228.60 ±2276.89 mm³ (13.4% more volume). Both acceptability thresholds were also met. The test for accuracy among smartphones 1, 2, and the laser scanner showed no statistically significant differences (P>.05) in all 4 parameters among the groups while also meeting both acceptability thresholds.
Conclusions
Smartphone cameras used to capture 48 overlapping gypsum cast ear images in a controlled environment generated 3D models parametrically similar to those produced by standard laser scanners.
Background: A maxillofacial prosthesis, an alternative to surgery for the rehabilitation of patients with facial disabilities (congenital or acquired due to malignant disease or trauma), are meant to replace parts of the face or missing areas of bone and soft tissue and restore oral functions such as swallowing, speech and chewing, with the main goal being to improve the quality of life of the patients. The conventional procedures for maxillofacial prosthesis manufacturing involve several complex steps, are very traumatic for the patient and rely on the skills of the maxillofacial team. Computer-aided design and computer-aided manufacturing have opened a new approach to the fabrication of maxillofacial prostheses. Our review aimed to perform an update on the digital design of a maxillofacial prosthesis, emphasizing the available methods of data acquisition for the extraoral, intraoral and complex defects in the maxillofacial region and assessing the software used for data processing and part design. Methods: A search in the PubMed and Scopus databases was done using the predefined MeSH terms. Results: Partially and complete digital workflows were successfully applied for extraoral and intraoral prosthesis manufacturing. Conclusions: To date, the software and interface used to process and design maxillofacial prostheses are expensive, not typical for this purpose and accessible only to very skilled dental professionals or to computer-aided design (CAD) engineers. As the demand for a digital approach to maxillofacial rehabilitation increases, more support from the software designer or manufacturer will be necessary to create user-friendly and accessible modules similar to those used in dental laboratories.
Background:
The literature has not yet validated the use of intraoral scanners (IOSs) for full-arch (FA) implant impression. Hence, the aim of this in vitro study was to assess and compare the trueness of 12 different IOSs in FA implant impression.
Methods:
A stone-cast model of a totally edentulous maxilla with 6 implant analogues and scanbodies (SBs) was scanned with a desktop scanner (Freedom UHD®) to capture a reference model (RM), and with 12 IOSs (ITERO ELEMENTS 5D®; PRIMESCAN® and OMNICAM®; CS 3700® and CS 3600®; TRIOS3®; i-500®; EMERALD S® and EMERALD®; VIRTUO VIVO® and DWIO®; RUNEYES QUICKSCAN®). Ten scans were taken using each IOS, and each was compared to the RM, to evaluate trueness. A mesh/mesh method and a nurbs/nurbs method were used to evaluate the overall trueness of the scans; linear and cross distances between the SBs were used to evaluate the local trueness of the scans. The analysis was performed using reverse engineering software (Studio®, Geomagics; Magics®, Materialise). A statistical evaluation was performed.
Results:
With the mesh/mesh method, the best results were obtained by CS 3700® (mean error 30.4 μm) followed by ITERO ELEMENTS 5D® (31.4 μm), i-500® (32.2 μm), TRIOS 3® (36.4 μm), CS 3600® (36.5 μm), PRIMESCAN® (38.4 μm), VIRTUO VIVO® (43.8 μm), RUNEYES® (44.4 μm), EMERALD S® (52.9 μm), EMERALD® (76.1 μm), OMNICAM® (79.6 μm) and DWIO® (98.4 μm). With the nurbs/nurbs method, the best results were obtained by ITERO ELEMENTS 5D® (mean error 16.1 μm), followed by PRIMESCAN® (19.3 μm), TRIOS 3® (20.2 μm), i-500® (20.8 μm), CS 3700® (21.9 μm), CS 3600® (24.4 μm), VIRTUO VIVO® (32.0 μm), RUNEYES® (33.9 μm), EMERALD S® (36.8 μm), OMNICAM® (47.0 μm), EMERALD® (51.9 μm) and DWIO® (69.9 μm). Statistically significant differences were found between the IOSs. Linear and cross distances between the SBs (local trueness analysis) confirmed the data that emerged from the overall trueness evaluation.
Conclusions:
Different levels of trueness were found among the IOSs evaluated in this study. Further studies are needed to confirm these results.
A systematic review was conducted in early 2019 to evaluate the articles published that dealt with digital workflow, CAD, rapid prototyping and digital image processing in the rehabilitation by maxillofacial prosthetics. The objective of the review was to primarily identify the recorded cases of orofacial rehabilitation made by maxillofacial prosthetics using computer assisted 3D printing. Secondary objectives were to analyze the methods of data acquisition recorded with challenges and limitations documented with various software in the workflow. Articles were searched from Scopus, PubMed and Google Scholar based on the predetermined eligibility criteria. 39 selected papers from 1992 to 2019 were then read and categorized according to type of prosthesis described in the papers. For nasal prostheses, Common Methods of data acquisition mentioned were computed tomography, photogrammetry and laser scanners. After image processing, computer aided design (CAD) was used to design and merge the prosthesis to the peripheral healthy tissue. Designing and printing the mold was more preferred. Moisture and muscle movement affected the overall fit especially for prostheses directly designed and printed For auricular prostheses, laser scanning was most preferred. For unilateral defects, CAD was used to mirror the healthy tissue over to the defect side. Authors emphasized on the need of digital library for prostheses selection, especially for bilateral defects. Printing the mold and conventionally creating the prosthesis was most preferred due to issues of proper fit and color matching. Orbital prostheses follow a similar workflow as auricular prosthesis. 3D photogrammetry and laser scans were more preferred and directly printing the prosthesis was favored in various instance. However, ocular prostheses fabrication was recorded to be a challenge due to difficulties in appropriate volume reconstruction and inability to mirror healthy globe. Only successful cases of digitally designed and printed iris were noted.
Aims: This study intended to evaluate the accuracy of low-cost approach such as a smartphone application in digitizing a facial defect for 3D modeling.
Methods: A stone model of a facial defect was scanned using industrial computed tomography as a reference scan. It was also scanned five times using a commercial laser scanner. 24 sequenced digital photographs were taken five times by smartphone at two elevations. These images were uploaded and processed by a cloud-based server to create virtual 3D models. The 3D datasets were geometrically evaluated and compared to the reference data using 3D evaluation software.
Results: There was a significant difference in the accuracy between the commercial laser scanner and smartphone application (P = 0.009).
Conclusion: The results showed that within the limits of this study, data acquisition with a smartphone for 3D modeling is not as accurate as commercially available laser scanning in reference to standard CT imaging.
Background
The utilization of intraoral scanning for manufacturing of complete dentures (CD) has been reported recently. However, functional border molding still cannot be supported digitally. A proof-of-concept trial shows two possible pathways to overcome this limitation by integrating a relining procedure into the digital workflow for CD manufacturing.
Case presentation
Intraoral scans and additional facial scans were performed with two various scanning systems for the rehabilitation of an edentulous male patient. The obtained raw data was aligned and used for the computer aided design (CAD) of the CD. The virtually constructed dentures were materialized in two various ways, considering rapid manufacturing and digital relining approaches in order to apply functionally molded borders.
Conclusion
The use of intraoral edentulous jaws scans in combination with the digital relining procedure may allow for fabrication of CD with functional borders within a fully digital workflow.
In this study, the practical accuracy (PA) of optical facial scanners for facial deformity patients in oral clinic was evaluated. Ten patients with a variety of facial deformities from oral clinical were included in the study. For each patient, a three-dimensional (3D) face model was acquired, via a high-accuracy industrial “line-laser” scanner (Faro), as the reference model and two test models were obtained, via a “stereophotography” (3dMD) and a “structured light” facial scanner (FaceScan) separately. Registration based on the iterative closest point (ICP) algorithm was executed to overlap the test models to reference models, and “3D error” as a new measurement indicator calculated by reverse engineering software (Geomagic Studio) was used to evaluate the 3D global and partial (upper, middle, and lower parts of face) PA of each facial scanner. The respective 3D accuracy of stereophotography and structured light facial scanners obtained for facial deformities was 0.58±0.11 mm and 0.57±0.07 mm. The 3D accuracy of different facial partitions was inconsistent; the middle face had the best performance. Although the PA of two facial scanners was lower than their nominal accuracy (NA), they all met the requirement for oral clinic use.
Objective:
The primary objective of this study was to compare the accuracy and time efficiency of an indirect and direct digitalization workflow with that of a three-dimensional (3D) printer in order to identify the most suitable method for orthodontic use.
Method and materials:
A master model was measured with a coordinate measuring instrument. The distances measured were the intercanine width, the intermolar width, and the dental arch length. Sixty-four scans were taken with each of the desktop scanners R900 and R700 (3Shape), the intraoral scanner TRIOS Color Pod (3Shape), and the Promax 3D Mid cone beam computed tomography (CBCT) unit (Planmeca). All scans were measured with measuring software. One scan was selected and printed 37 times on the D35 stereolithographic 3D printer (Innovation MediTech). The printed models were measured again using the coordinate measuring instrument.
Results:
The most accurate results were obtained by the R900. The R700 and the TRIOS intraoral scanner showed comparable results. CBCT-3D-rendering with the Promax 3D Mid CBCT unit revealed significantly higher accuracy with regard to dental casts than dental impressions. 3D printing offered a significantly higher level of deviation than digitalization with desktop scanners or an intraoral scanner. The chairside time required for digital impressions was 27% longer than for conventional impressions.
Conclusion:
Conventional impressions, model casting, and optional digitization with desktop scanners remains the recommended workflow process. For orthodontic demands, intraoral scanners are a useful alternative for full-arch scans. For prosthodontic use, the scanning scope should be less than one quadrant and three additional teeth.
PurposeThe aim of this study is to present the development of a new technique to obtain 3D models using photogrammetry by a mobile device and free software, as a method for making digital facial impressions of patients with maxillofacial defects for the final purpose of 3D printing of facial prostheses. Methods
With the use of a mobile device, free software and a photo capture protocol, 2D captures of the anatomy of a patient with a facial defect were transformed into a 3D model. The resultant digital models were evaluated for visual and technical integrity. The technical process and resultant models were described and analyzed for technical and clinical usability. ResultsGenerating 3D models to make digital face impressions was possible by the use of photogrammetry with photos taken by a mobile device. The facial anatomy of the patient was reproduced by a *.3dp and a *.stl file with no major irregularities. 3D printing was possible. Conclusions
An alternative method for capturing facial anatomy is possible using a mobile device for the purpose of obtaining and designing 3D models for facial rehabilitation. Further studies must be realized to compare 3D modeling among different techniques and systems. Clinical implicationFree software and low cost equipment could be a feasible solution to obtain 3D models for making digital face impressions for maxillofacial prostheses, improving access for clinical centers that do not have high cost technology considered as a prior acquisition.
Objectives:
Little information is available on the impact of different scan strategies on the accuracy of full-arch scans with intraoral scanners. The aim of this in-vitro study was to investigate the trueness and precision of full-arch maxillary digital impressions comparing three scan strategies.
Method and materials:
Three scan strategies (A, B, and C) were applied each five times on one single model (A, first buccal surfaces, return from occlusal-palatal; B, first occlusal-palatal, return buccal; C, S-type one-way). The TRIOS Pod scanner (3shape, Copenhagen, Denmark) with a color detector was used for these digital impressions. A cast of a maxillary dentate jaw was fabricated and scanned with an industrial reference scanner. This full-arch data record was digitally superimposed with the test scans (trueness) and within-group comparison was performed for each group (precision). The values within the 90/10 percentiles from the digital superimposition were used for calculation and group comparisons with nonparametric tests (ANOVA, post-hoc Bonferroni).
Results:
The trueness (mean ± standard deviation) was 17.9 ± 16.4 μm for scan strategy A, 17.1 ± 13.7 μm for B, and 26.8 ± 14.7 μm for C without statistically significant difference. The precision was lowest for scan strategy A (35.0 ± 51.1 μm) and significantly different to B (7.9 ± 5.6 μm) and C (8.5 ± 6.3 μm).
Conclusions:
Scan strategy B may be recommended as it provides the highest trueness and precision in full-arch scans and therefore minimizes inaccuracies in the final reconstruction.
Direct silicone printing has been reported for the manufacture of interim facial prostheses. The recent advancements in printing hardware have allowed for multimaterial simultaneous silicone printing with 4 nozzles. With this technology, an auricular prosthesis was printed with various grades of Shore hardness. A few analog steps, including polishing, sealing, coloring, and relining, resulted in an individualized prosthesis with a thin frontal margin and smooth transition into the adjacent tissue. It was considered a definitive treatment option.
Statement of problem
Intraoral scanners (IOSs) are based on light-optical imaging methods. However, little is known about whether the ambient light in dental practices influences the accuracy and scanning time of the IOS.
Purpose
The purpose of this in vitro study was to investigate the influence of different illuminations on the accuracy of 4-unit and complete-arch scans of 6 IOSs. In addition, the required scanning time was evaluated.
Material and methods
A reference structure was attached to the first premolars (P) and second molars (M) in both quadrants (L/R) of a maxillary model. The resulting measured distances were M1-P1, M2-P2, P1-P2, and M1-M2. The investigation included 6 IOSs: TRIOS 3 (TRI), Cerec Omnicam (OC), iTero Element (ITE), CS 3600 (CS), Planmeca Emerald (EME), and GC Aadva (AAD). With each IOS, 17 scans at different illuminances (100, 500, 1000, and 5000 lux) were performed (N = 408). The precision and trueness for all distances were determined, and the scanning time was recorded. For statistical analyses, the Levene tests (precision) and 1-way analysis of variance with the post hoc Tukey honestly significant difference and Games-Howell tests (trueness) were calculated.
Results
Illuminance significantly influenced the trueness of 4-unit scans for OC, EME, and AAD. TRI, OC, ITE, and CS demonstrated comparable results. AAD (>96 ±22 μm; 1000 lux) and EME (>248 ±88 μm; 500 lux) revealed greater deviations. For complete-arch scans, illuminance did not influence TRI and AAD, but significant variations were detected for ITE, CS, EME, and AAD. The least deviations were achieved with TRI and OC. The scanning time was extended for all IOSs except ITE at more than 500 lux. The shortest scanning times with OC and EME were recorded at 100 lux; with TRI, CS, and AAD at 500 lux; and with ITE at both 100 and 5000 lux. At all illuminances, the fastest scans were obtained with TRI.
Conclusions
Ambient light was found to influence the accuracy and scanning time of IOSs. This influence varies depending on the device. For 4-unit scans, the effect was not clinically relevant, but for complete-arch scans, accuracy and scanning time can be improved with appropriate lighting.
STATEMENT OF PROBLEM:
Digital waxing procedures should be guided by facial references to improve the esthetic outcome of a restoration. The development of facial scanners has allowed the digitalization of the extraoral soft tissues of the patient's face. However, the reliability of facial digitizers is questionable.
PURPOSE:
The purpose of this study was to evaluate the accuracy (trueness and precision) of extraoral 3D facial reconstructions performed by using a dual-structured light facial scanner and to measure the interexaminer variability.
MATERIAL AND METHODS:
Ten participants were included. Six soft-tissue landmarks were determined on each participant, specifically reference (Ref), glabella (Gb), subnasal (Sn), menton (Me), chelion right (ChR), and chelion left (ChL). Interlandmark distances Ref-Sn, Sn-Gb, Ref-Gb, Sn-Me, and ChR-ChL (intercommissural) were measured by 2 different operators by using 2 different methods: directly on the participant' face (manual group) and digitally (digital group) on the 3D facial reconstruction of the participant (n=20). For the manual group, interlandmark measurements were made by using digital calipers. For the digital group, 10 three-dimensional facial reconstructions were acquired for each participant by using a dual-structured light facial scanner (Face Camera Pro Bellus; Bellus3D). Interlandmark measurements were made by using an open-source software program (Meshlab; Meshlab). Both operators were used to note 10 measurements for each manual and digital interlandmark distance per participant. The intraclass correlation coefficient between the 2 operators was calculated. The Shapiro-Wilk test revealed that the data were not normally distributed. The data were analyzed by using the Mann-Whitney U test.
RESULTS:
Significant differences were found between manual and digital interlandmark measurements in all participants. The mean value of the manual and digital group discrepancy was 0.91 ±0.32 mm. The dual-structured light facial scanner tested obtained a trueness mean value of 0.91 mm and a precision mean value of 0.32 mm. Trueness values were always higher than precision mean values, indicating that precision was relatively high. The intraclass correlation coefficient between the 2 operators was 0.99.
CONCLUSIONS:
The facial digitizing procedure evaluated produced clinically acceptable outcomes for virtual treatment planning. The interexaminer reliability between the 2 operators was rated as excellent, suggesting that the type of facial landmark used in this study provides reproducible results among different examiners.
PURPOSE:
To evaluate the feasibility and accuracy of noncontact three-dimensional (3D) digitization systems for capturing facial defects.
MATERIALS AND METHODS:
A stone model of a facial defect was digitized using high-accuracy industrial computed tomography as a reference scan. The model was also scanned using four different types of noncontact 3D digitizers: a laser beam light-sectioning technology with camera system and three different stereophotogrammetry systems. All 3D images were reconstructed with corresponding software and saved as standard triangulated language (STL) files. The 3D datasets were geometrically evaluated and compared to the reference data using 3D evaluation software. Kruskal-Wallis H tests were performed to assess differences in absolute 3D deviations between scans, with statistical significance defined as P < .05.
RESULTS:
The four noncontact 3D digitization systems were feasible for digitizing the facial defect model, although the median 3D deviation of the four digitizers varied. There was a significant difference in accuracy among the digitizers (P < .001).
CONCLUSION:
Digitization of facial defect models using various noncontact 3D digitizers appears to be feasible and is most accurate with laser beam light-sectioning technology. Further investigations assessing digitization of facial defects among patients are required to clinically verify the results of this study.
PURPOSE:
To identify trends in the application of various types of digital technologies in maxillofacial prosthetics by identifying these digital technologies and their characteristics and reviewing the prevalence of applied digital technologies and their recent trends in the maxillofacial prosthetics literature.
MATERIALS AND METHODS:
Five leading peer-reviewed prosthodontics journals were manually searched for maxillofacial prosthetics articles on the use of digital technologies published from January 2008 to December 2017. Descriptive statistics were used to analyze data collected on productivity, type of digital technology used, type of article, type of defect, number of authors, and geographic distribution.
RESULTS:
Of the 336 maxillofacial prosthetics articles screened, 87 (26%) were selected for analysis. A remarkable increase was found in article productivity in the last 5 years (63%) compared to the first 5 years (37%). There was also a notable increase over the last 10 years in all digital technologies used except for evaluation technologies, which remained almost constant. Case reports most frequently mentioned use of digitization technologies (61%), design technologies (66%), and rapid prototyping technologies (66%). Original research articles most frequently mentioned use of evaluation technologies (89%); 39% of these technologies were used for intraoral defects and 27% for extraoral defects. Most often, articles had four to five authors (54%). Most published articles were from the Asia-Pacific region (44%), followed by North America (22%) and Europe (20%).
CONCLUSION:
Although the application of digital technologies reported in the maxillofacial prosthetics literature has increased notably in leading prosthodontics journals over the last 10 years, total article productivity has remained relatively small.
Statement of problem:
Fabrication of conventional facial prostheses is a labor-intensive process which traditionally requires an impression of the facial defect and surrounding tissues. Inaccuracies occur during the facial moulage because of soft-tissue compression, the patient's reflex movements, or the lack of support for the impression material. A variety of 3D imaging techniques have been introduced during the production of facial prostheses. However, the accuracy of the different imaging techniques has not been evaluated sufficiently in this clinical context.
Purpose:
The purpose of this in vitro study was to compare the difference in accuracy of capturing oncology facial defects with multimodal image fusion and laser scanning against a cone beam computed tomography (CBCT) reference scan.
Material and methods:
Ten gypsum casts of oncology facial defects were acquired. To produce reference models, a 3D volumetric scan was obtained using a CBCT scanner and converted into surface data using open-source medical segmentation software. This model was cropped to produce a CBCT mask using an open-source system for editing meshes. The multimodal image fusion model was created using stereophotogrammetry to capture the external facial features and a custom optical structured light scanner to record the defect. The gypsum casts were also scanned using a commercial 3D laser scanner to create the laser-scanned model. Analysis of the best fit of each experimental model to the CBCT mask was performed in MeshLab. The unsigned mean distance was used to measure the absolute deviation of each model from the CBCT mask. A paired-samples t test was conducted to compare the mean global deviation of the 2 imaging modalities from the CBCT masks (α=.05).
Results:
A statistically significant difference was found in the mean global deviation between the multimodal imaging model (220 ±50 μm) and the laser-scanned model (170 ±70 μm); (t(9)=2.56, P=.031). The color error maps illustrated that the greatest error was located at sites distant to the prosthesis margins.
Conclusions:
The laser-scanned models were more accurate; however, the mean difference of 50 μm is unlikely to be clinically significant. The laser scanner had limited viewing angles and a longer scan time which may limit its transferability to maxillofacial practice.
Prosthodontic rehabilitation of a congenital or acquired defect of the ear is considered a challenging and skill‐dependent procedure. This technical report describes a novel approach for direct digital scanning of the unaffected contralateral ear using an intraoral scanner and external markers. The obtained digital data of the ear was exported, digitally mirrored, and successfully positioned to a virtual model of a human head with a missing ear. This technique demonstrates the potential application of CAD/CAM in the design and fabrication of an auricular prosthesis for patients with a unilateral ear defect.
This article is protected by copyright. All rights reserved
Purpose:
To set up the digital database (DDB) of various anatomical parts, skin details and retention elements in order to simplify the digital workflow of facial prostheses manufacturing; and to quantify the reproduction of skin wrinkles on the prostheses prototypes with stereolithography (SLA) and direct light processing (DLP) methods.
Methods:
Two structured light scanners were used to obtain the nasal and auricle forms of 50 probands. Furthermore, the ala nasi and scapha areas were captured with the digital single lens reflex camera and saved in jpeg format. The four magnetic retention elements were remodeled in computer aided design (CAD) software. The 14 test blocks with embossed wrinkles of 0.05-0.8mm were printed with SLA and DLP methods and afterwards analyzed by means of profilometry and confocal microscopy.
Results:
The introduced DDB allows for production of customized facial prosthesis and makes it possible to consider the integration of concrete retention elements on the CAD stage, which makes the prosthesis modelling more predictable and efficient. The obtained skin structures can be applied onto the prosthesis surface for customization. The reproduction of wrinkles from 0.1 to 0.8mm in depth may be associated with the loss of 4.5%-11% of its profile with SLA or DLP respectively. Besides, the reproduction of 0.05mm wrinkles may be met with up to 40% profile increasement.
Conclusions:
The utilization of DDB may simplify the digital workflow of facial prostheses manufacturing. The transfer of digitally applied skin wrinkles till the prostheses' prototypes may be associated with deviations from 11 to 40%.
Aims: This study sought to identify trends in the application of various types of digital technologies in maxillofacial prosthetics by (1) identifying these digital technologies and their characteristics, and (2) reviewing the prevalence of applied digital technologies and the recent trends in the maxillofacial prosthetic literature.
Methods: We manually searched and reviewed 5 leading peer-reviewed prosthodontic journals for maxillofacial prosthetic articles on the use of digital technologies that were published from January 2008 to December 2017. Descriptive statistics were used to analyze data collected on productivity, type of digital technology used, type of published article, type of defect, number of authors, and geographic distribution.
Results: Among 336 maxillofacial prosthetic articles screened, 87 (26%) were selected for analysis. We found a remarkable increase in article productivity in the last 5 years (63%) compared with the first 5 years (37%). There was a notable increase over the last 10 years in all digital technologies used except for evaluation technologies, which remained almost constant. Case reports most frequently mentioned use of digitization technologies (61%), design technologies (66%), and rapid prototyping technologies (66%). Original research articles most frequently mentioned use of evaluation technologies (89%); 39% of these technologies were used for intraoral defects and 27 % for extraoral defects. Most often, articles had 4-5 authors (54%). Most published articles were from the Asia-Pacific region (44%), followed by North America (22%) and Europe (20%).
Conclusion: Although the application of digital technologies reported in the maxillofacial prosthetic literature has increased notably in leading prosthodontic journals over the last 10 years, total article productivity remained relatively small.
Aim:
Assess the feasibility, validity and precision of multimodal image fusion to capture oncology facial defects based on plaster casts.
Methods:
Ten casts of oncology facial defects were acquired. To create gold standard models, a 3D volumetric scan of each cast was obtained with a cone beam computed tomography (CBCT) scanner (NewTomVG). This was converted into surface data using open-source medical segmentation software and cropped to produce a CBCT mask using an open-source system for editing meshes. For the experimental model, the external facial features were captured using stereophotogrammetry (DI4D) and the defect was recorded with a custom optical structured light scanner. The two meshes were aligned, merged and resurfaced using MeshLab to produce a fused model. Analysis was performed in MeshLab on the best fit of the fused model to the CBCT mask. The unsigned mean distance was used to measure the absolute deviation of each model from the CBCT mask. To assess the precision of the technique, the process of producing the fused model was repeated to create five models each for the casts representing the best, middle and worst results.
Results:
Global mean deviation was 0.22 mm (standard deviation 0.05 mm). The precision of the method appeared to be acceptable although there was variability in the location of the error for the worst cast.
Conclusion:
This method for merging two independent scans to produce a fused model shows strong potential as an accurate and repeatable method of capturing facial defects. Further research is required to explore its clinical use.
Purpose: The utilization of CAD/CAM and Additive Manufacturing in maxillofacial prosthetics has been widely acknowledged. Rapid prototyping (RP) can be considered for manufacturing of auricular prostheses. Therefore so-called prostheses replicas can be fabricated by digital means. The objective of this study was to identify a superior additive manufacturing method to fabricate auricular prosthesis replicas (APRs) within a digital workflow.
Material and methods: Auricles of 23 healthy subjects (mean age of 37.8 years) were measured in-vivo with respect to an anthropometrical protocol. Landmarks were volumized with fiducial balls for 3D-scanning utilizing a handheld structured light scanner. The 3D CAD-dataset was post-processed and the same anthropometrical measurements were carried out in the CAD software with the digital lineal. Each CAD-dataset was materialized using fused deposition modelling (FDM), selective laser sintering (SLS), and stereolithography (SL), constituting 53 APR-samples. All distances between the landmarks were measured on the APRs. After the determination of the measurement error within the five data groups (In-vivo, CAD, FDM, SLS, SL), the mean values were compared using matched pairs method. To this, the in-vivo and CAD dataset were set as references. Conclusively, the surface structure of the APRs was qualitatively evaluated with stereomicroscopy and profilometry to ascertain the level of skin detail reproduction.
Results: The anthropometrical approach showed drawbacks in measuring the protrusion of the ear’s helix. The measurement error within all groups of measurements was calculated between 0.20 mm and 0.29 mm, implying a high reproducibility. The lowest mean differences of 53 produced APRs were found in FDM (0.43%) followed by SLS (0.54%) and SL (0.59%) – compared to In-vivo, and again in FDM (0.20%) followed by SL (0.36%) and SLS (0.39%) – compared to CAD. None of these values exceed the threshold of clinical relevance (1.5%). However, the qualitative evaluation revealed slight shortcomings in skin reproduction for all methods: reproduction of skin details exceeding 0.192 mm in depth was feasible.
Conclusion: FDM showed the superior dimensional accuracy and best skin surface reproduction. Moreover, digital acquisition and CAD post-processing seems to play a more important role for the outcome than the utilized AM method.
The utilization of additive manufacturing (AM) technology for the production of auricular
prostheses has been widely acknowledged. However, few studies and case history reports
have evaluated the esthetic outcomes of AM prostheses compared to those of conventionally
manufactured prostheses. In this case history report, three manufacturing approaches—
conventional, indirect, and direct mold preparation—were assessed for their esthetic
outcomes in the same patient.
Statement of problem:
Whether cone beam computed tomography (CBCT) images can be used for the fabrication of computer-aided design/computer-aided manufacturing (CAD/CAM) restorations is unknown.
Purpose:
The purpose of this in vitro study was to evaluate the marginal fit of CAD/CAM restorations fabricated by using data from CBCT scans with 3 different voxels and laser scanner images.
Material and methods:
A crown preparation was made on an extracted premolar tooth according to ceramic crown preparation guidelines. The prepared tooth was scanned with a 3-dimensional (3D) extraoral laser scanner (D900; 3Shape), and CBCT scans were also made with an i-CAT cone beam 3D imaging system at 3 different voxel resolution settings: 0.125 mm, 0.20 mm, and 0.30 mm. The 3D images obtained from the laser scanner and CBCT scans were sent to CAD software, and a crown design was completed. Information was sent to CAM software to mill the crowns from poly(methyl methacrylate) (PMMA) blocks (n=9 from the laser scanner and 27 from 3 different CBCT scans). A total of 144 images (4 groups, 9 crowns per group, 4 sites per crown) were measured for vertical marginal discrepancy under a stereoscopic zoom microscope. One-way analysis of variance (ANOVA) was used to analyze the data. According to the assumption of homogeneity of variance, the post hoc Tukey multiple comparison test was performed (α=.05).
Results:
The marginal gap values of crowns fabricated with an extraoral laser scanner were significantly lower than those of crowns fabricated with 0.3-, 0.2-, and 0.125-voxel CBCT images (P<.001). The marginal gap was greater when 0.3- and 0.2-voxel CBCT images were used than when 0.125-voxel CBCT images were used (P<.001).
Conclusions:
Crowns fabricated with the laser scanner images had lower and clinically acceptable marginal discrepancies than crowns fabricated with CBCT images in 3 different voxels. Of all the CBCT scans, only images with 0.125 voxel produced crowns with clinically acceptable marginal discrepancy.
Implant-retained auricular prostheses are a successful prosthetic treatment option for patients who are missing their ear(s) due to trauma, oncology, or birth defects. The prosthetic ear is aesthetically pleasing, composed of natural looking anatomical contours, shape, and texture along with good color that blends with surrounding existing skin. These outcomes can be optimized by the integration of digital technologies in the construction process. This report describes a sequential process of reconstructing a missing left ear by digital technologies. Two implants were planned for placement in the left mastoid region utilizing specialist biomedical software (Materialise, Belgium). The implant positions were determined underneath the thickest portion (of anti-helix area) left ear that is virtually simulated by means of mirror imaging of the right ear. A surgical stent recording the implant positions was constructed and used in implant fixtures placement. Implants were left for eight weeks, after which they were loaded with abutments and an irreversible silicone impression was taken to record their positions. The right existing ear was virtually segmented using the patient CT scan and then mirror imaged to produce a left ear, which was then printed using 3D printer (Z Corp, USA). The left ear was then duplicated in wax which was fitted over the defect side. Then, it was conventionally flasked. Skin color was digitalized using spectromatch skin color system (London, UK). The resultant silicone color was mixed as prescribed and then packed into the mold. The silicone was cured conventionally. Ear was trimmed and fitted and there was no need for any extrinsic coloring. The prosthetic ear was an exact match to the existing right ear in shape, skin color, and orientation due to the great advantages of technologies employed. Additionally, these technologies saved time and provided a base for reproducible results regardless of operator.
Even though modern surgical techniques are dominating reconstructive facial procedures, the capability to use facial epitheses for reconstruction is still an important skill for the maxillofacial surgeon. We present an international multicenter analysis to clarify which techniques are used to fixate facial prostheses. We contacted all maxillofacial departments in Germany, Austria, Switzerland and Norway which were registered with the German society for oral and maxillofacial surgery (DGMKG). These centers were asked via electronical mail to provide information on the type of epithesis fixation systems currently in use. The return rate from 58 departments was 43.1% (n = 25). Overall, implant fixation was the preferred fixation system (92%). Plates were the second most common fixation technique (32%). No centers reported the standard use of non-invasive fixation techniques for permanent epithesis fixation. The main retention systems in use were magnets (24/25), other retention systems are used much less often. The current preferred fixation technique for facial epitheses consists of implant-based, magnet-fixated epitheses. For nasal prostheses, a plate-based, magnet-fixated system is often used.
Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
In order to restore an extraoral maxillofacial defect, a moulage impression is commonly made with traditional impression materials. This technique has some disadvantages, including distortion of the site due to the weight of the impression material, changes in tissue location with modifications of the patient position, and the length of time and discomfort for the patient due to the impression procedure and materials used. The use of the commercially available 3dMDface™ System creates 3D images of soft tissues to form an anatomically accurate 3D surface image. Rapid prototyping converts the virtual designs from the 3dMDface™ System into a physical model by converting the data to a ZPrint (ZPR) CAD format file and a stereolithography (STL) file. The data, in conjunction with a Zprinter® 450 or a Stereolithography Apparatus (SLA), can be used to fabricate a model for prosthesis fabrication, without the disadvantages of the standard moulage technique. This article reviews this technique and how it can be applied to maxillofacial prosthetics.
The aim of this study was to compare the clinical facial soft tissue measurements with the measurements of facial plaster cast, three-dimensional scanned facial plaster cast, 3-dimensional digital photogrammetrical images, and three-dimensional laser scanner images.
Three-dimensional facial images of 15 adults were obtained with stereophotogrammetry and a three-dimensional laser scanner. Facial models of subjects were obtained using silicone impression and were scanned. Landmarks were marked on the subjects and plaster casts, digitized on three-dimensional models, and measured in Mimics 12.0 software (Materialise's Interactive Medical Image Control System, Leuven, Belgium).
No statistically significant differences were found between all three-dimensional measurement methods in mouth width, philtrum median height, and nasal width. Comparison of clinical measurements with facial plaster cast measurements revealed that philtral width, nasal tip protrusion, and right lip and nostril heights were wider and longer in clinical measurements than in facial plaster cast measurements. Comparison of clinical measurements to the laser scanned and stereophotogrammetric model measurements revealed that philtrum lateral and lip heights and philtral width were significantly different between methods. When laser scanned and stereophotogrammetric measurements were compared, significant differences were observed in lip and nostril heights.
Facial impression may be problematic owing to the depression caused by the impression material especially on the tip of the nose. Laser scanning is not sensitive enough to visualize the deeper indentations such as nostrils. Stereophotogrammetry is promising for three-dimensional facial measurements and even will be better when color identification between mucocutaneous junctions of the lip region is achieved.
Technology has the potential to transform the fabrication process of facial prosthetics. The purpose of this review is to highlight the pertinent technological advances in computerized shade selection, three-dimensional digital photography, virtual surgical planning, surface scanning, and three-dimensional imaging to obtain the wax pattern.
There have been a few reported studies documenting the effect of computerized color formulations for facial prosthesis. The technology is still in its infancy and may serve as a tool to manage metamerism and to complement the subjective clinical assessment of the clinician. Three-dimensional photography, surface scanning, and three-dimensional imaging have been used successfully in the fabrication of facial prostheses. Software programs which allow the clinician to plan virtually implant placement allows the treatment planning process to be much more prosthetically driven. Even with the technological advances, it is perhaps most important to remember the basics of proper preparation of the defect to accept the prosthesis.
The incorporation of technology into the fabrication process of facial prostheses can potentially transform the treatment process from a time-consuming artistically driven process to being a reconstructive biotechnology process.
In modern anthropometry of such complex structures as the face, three-dimensional scanning techniques have become more and more common. Before establishing them as a criterion standard, however, meticulous evaluation of their precision and accuracy under both ideal and clinical circumstances is essential. Potential sources of error need to be identified and addressed.
Under ideal circumstances, a phantom is used to examine the precision and accuracy of the 3dMD system. A clinical setting is simulated by varying different parameters such as angle, distance, and system reregistration, as well as data evaluation under different levels of magnification.
The handling of the system was unproblematic in matters of data acquisition and data analysis. It was very reliable, with a mean global error of 0.2 mm (range, 0.1-0.5 mm) for mannequin head measurements. Neither the position of the head nor that of the camera influenced these parameters. New referencing of the system did not influence precision and accuracy.
The precision and accuracy of the tested system are more than sufficient for clinical needs and greater than those of other methods, such as direct anthropometry and two-dimensional photography. The evaluated system can be recommended for evaluation and documentation of the facial surface and could offer new opportunities in reconstructive, orthognathic, and craniofacial surgery.
An auricular prosthesis is an artificial substitute for the auricle; the term epithesis is used synonymously. A myriad of materials have been used in the long history of anaplastology. However, the breakthrough came with the introduction of modern silicones and their colorings. While there are still indications for noninvasive methods of retention, such as medical adhesives, the best and most reliable method of fixation is bone anchorage. Long-lasting osseointegration with reaction-free skin penetration can be achieved with titanium implants. The first system used extraorally was the Brånemark flange fixture. Later, different solitary titanium implants were introduced, such as the ITI system. A different strategy used the titanium grids (Epitec) or plates (Epiplating) derived from osteosynthesis systems. These systems are fixed subperiostally with several bone screws, and are therefore also labeled as grouped implants. With these modern developments, secure retention can also be achieved in unfavorable anatomical situations. Advantages of implant-retained auricular prostheses include: optimal camouflage, predictable cosmetic results, fast rehabilitation, no donor site morbidity and early detection of tumor recurrence. Depending on the clinical setting, prosthetic rehabilitation can be a viable treatment option, and more than just an alternative to plastic reconstructive surgery.
A two-stage impression technique that uses polyvinyl siloxane and irreversible hydrocolloid in a custom impression tray is described. The technique records the tissues to be contacted by the facial prosthesis with minimal distortion with the patient in an upright position and facial musculature at rest. The procedure is simple, accurate, and it eliminates some of the shortcomings of other techniques.
The conventional impression technique for manufacturing facial prostheses has the disadvantage of deforming the soft tissues because of the tension caused by the impression material, as well as causing discomfort to the patient. The purpose of this study was to establish a system that allows contact-free reproduction of the facial surface combined with computer-assisted design and fabrication of facial prostheses.
Three-dimensional data of the facial surface were obtained using an optical acquisition system based on the method of phase-measuring profilometry. A sensor head with a fringe projector and two CCD cameras for photogrammetric triangulation were used in connection with a PC for measurement control and data evaluation. Software for computer-assisted design of the facial surface to be reconstructed was developed. A prototype facial prosthesis was fabricated using stereolithography. The system was tested using a modified puppet head. First clinical tests were performed with a patient who had undergone maxillofacial surgery including the resection of one eye.
Three-dimensional data acquisition and imaging allow visualization of a whole face without causing tension or neuromuscular reaction. As surface brightness is also part of the digital model, it is even more realistic than a plaster cast. The stereolithographic object showed good marginal fit and satisfactory shape.
The presented technique allows three-dimensional data reproduction of the facial surface, computer-assisted design of a facial prosthesis, and transfer to a rapid prototyping unit. The system has obvious advantages over conventional impression techniques. Further clinical trials are planned to evaluate the clinical success of the technique.
Achieving adaptation of an auricular prosthesis begins with an accurate impression. It is important to consider how the selection of the impression materials will affect the final outcome of the prosthesis. A procedure is presented to minimize the distortion of the soft tissues caused by the impression materials and procedure. The procedure consists of splinting the implant impression copings, then recording the soft tissue in silicone impression material, followed by the application of acrylic tray resin to provide rigidity.
Sampling experiments were performed to investigate mean square error and bias in estimates of mean shape produced by different geometric morphometric methods. The experiments use the isotropic error model, which assumes equal and independent variation at each landmark. The case of three landmarks in the plane (i.e., triangles) was emphasized because it could be investigated systematically and the results displayed on the printed page. The amount of error in the estimates was displayed as RMSE surfaces over the space of all possible configurations of three landmarks. Patterns of bias were shown as vector fields over this same space. Experiments were also performed using particular combinations of four or more landmarks in both two and three dimensions. It was found that the generalized Procrustes analysis method produced estimates with the least error and no pattern of bias. Averages of Bookstein shape coordinates performed well if the longest edge was used as the baseline. The method of moments (Stoyan, 1990, Model. Biomet. J. 32, 843) used in EDMA (Lele, 1993, Math. Geol. 25, 573) exhibits larger errors. When variation is not small, it also shows a pattern of bias for isosceles triangles with one side much shorter than the other two and for triangles whose vertices are approximately collinear causing them to resemble their own reflections. Similar problems were found for the log-distance method of Rao and Suryawanshi (1996, Proc. Nat. Acad. Sci. 95, 4121). These results and their implications for the application of different geometric morphometric methods are discussed.
Irreversible hydrocolloid is widely used as an impression material for fabrication of extraoral maxillofacial impressions. A disadvantage of irreversible hydrocolloid, however, is its limited working time.
This study tested the compression strength (elastic recovery) and working and setting times for an irreversible hydrocolloid impression material after a retarder was added.
The irreversible hydrocolloid (Jeltrate) was mixed with water in a standard water/powder mixture of 18 mL (1 unit) of water and 7 g (1 unit) of the impression material. Test specimens (n = 3) were prepared by adding 2, 4, 6, and 8 drops of monobasic sodium phosphate (the retarder) to each. Three other specimens, to which no retarder was added, served as the control. Specimens were prepared according to the American National Standards Institute/American Dental Association's specification no.18 guidelines for irreversible hydrocolloid impression material. Immediately after the specimens were prepared, the flat end of a polished rod of poly(methyl methacrylate) was placed in contact with its exposed surface and quickly withdrawn. The working-time experiment was a pass/fail test conducted 30 seconds before the initial setting time. The initial setting time was established as extending from the start of the mix to the time when the impression material no longer adhered to the end of the rod. To determine how the compressive strength of the modified irreversible hydrocolloid (with retarder added) compared with that of the control, the mean stress at maximum load (Mpa) was analyzed. The compressive strength (MPa) was calculated. Statistical analysis consisted of descriptive statistics and regression analyses.
The results of this experiment demonstrated that the elastic recovery of the irreversible hydrocolloid did not change with the addition of sodium phosphate (2 to 8 drops). The percent recovery with was 95.95% +/-.42%, 96.33% +/-.82%, and 96.28% +/-.53% for 0 (control), 2 and 8 drops, respectively. Average setting times for control specimens were 2 minutes 20 seconds +/- 0 seconds for the control specimen (0 drops) to 11 minutes 20 seconds +/- 1 minute 50 seconds for the test specimen with 8 drops. There was a direct relationship (R(2) = 0.85) between the number of drops added and the setting time. All control specimens and test specimens containing 2, 4, 6, and 8 drops of monobasic sodium phosphate produced acceptable levels of elastic recovery (> or =95%).
Within the limitations of this study, predictable longer working and setting times were demonstrated for the irreversible hydrocolloid specimens with 1 to 8 drops of the sodium phosphate solution tested. The specimens with 8 drops of retarder solution exhibited variable setting times and would not be suitable for clinical use. The compressive strength of the modified irreversible hydrocolloid material tested was compromised because of the addition of sodium phosphate solution; however, recovery from deformation remained satisfactory as retarder solution was added.
Cancer surgery, malformation or trauma may cause broad facial defects that cannot be covered by patients because of their exposed site. Such defects lead to functional deficits and enormous psychological strain and require rehabilitation at all ages. Prosthetic supply has been developed into a functional and aesthetic alternative to plastic and reconstructive surgery.
The condensed experience with prosthetic supply after persistent surgical defects of more than twenty patients during the recent years is described.
Efficient prosthetic supply in the exposed facial area requires a well scheduled and close cooperation between the surgeon and anaplastologist. Preoperative diagnostic evaluation and operative filling of the magnetic fixation in cooperation with the anaplastologist provide a satisfying functional and cosmetic prosthetic outcome for the patient. Advantages of this procedure combine early cosmetic rehabilitation with the option to directly investigate the tumor site after resection. Novel magnet systems provide a high degree of flexibility combined with confident fixation.
Prosthetic rehabilitation should be offered and discussed with patients ahead of cancer surgery in the head and neck area. This procedure should be considered in particular in patients that reject or are not feasible for multi-step reconstructive surgery.
This article describes an impression technique to transfer implant positions to the definitive cast using magnetic attachments splinted with acrylic resin for an implant-retained orbital prosthesis. The acrylic resin transfer device that incorporated the magnets was also used as the acrylic resin magnet substructure for the silicone orbital prosthesis.
Facial moulage: the effect of a retarder on compressive strength and working and setting times of irreversible hydrocolloid impression material
- Lemon
OpenEpi: open source epidemiologic statistics for public health
- S K Dean
- A G Soe
S.K. Dean AG, Soe M.M., OpenEpi: open source epidemiologic statistics for public
health. http://www.openepi.com/Menu/OE_Menu.html [Zugriff 10.03.21],
(2015).
- S Volkenstein
- S Dazert
- K Jahnke
- M Schneider
- A Neumann
S. Volkenstein, S. Dazert, K. Jahnke, M. Schneider, A. Neumann, [Prosthetic supply
of tissue defects in head and neck surgery], Laryngorhinootologie 86 (2007)
854-860.
Evaluation of marginal fit of CAD/CAM restorations fabricated through cone beam computerized tomography and laboratory scanner data
- E Eker
- T B Ozcelik
- N Rathi
- B Yilmaz
E. Ş eker, T.B. Ozcelik, N. Rathi, B. Yilmaz, Evaluation of marginal fit of CAD/CAM
restorations fabricated through cone beam computerized tomography and
laboratory scanner data, J. Prosthet. Dent. 115 (2016) 47-51.