CAD/CAM ear model and virtual construction of the mold

Exploring the Practical Applications of Artificial Intelligence, Deep Learning, and Machine Learning in Maxillofacial Surgery: A Comprehensive Analysis of Published Works

Artificial intelligence (AI), deep learning (DL), and machine learning (ML) are computer, machine, and engineering systems that mimic human intelligence to devise procedures. These technologies also provide opportunities to advance diagnostics and planning in human medicine and dentistry. The purpose of this literature review was to ascertain the applicability and significance of AI and to highlight its uses in maxillofacial surgery. Our primary inclusion criterion was an original paper written in English focusing on the use of AI, DL, or ML in maxillofacial surgery. The sources were PubMed, Scopus, and Web of Science, and the queries were made on the 31 December 2023. The search strings used were "artificial intelligence maxillofacial surgery", "machine learning maxillofacial surgery", and "deep learning maxillofacial surgery". Following the removal of duplicates, the remaining search results were screened by three independent operators to minimize the risk of bias. A total of 324 publications from 1992 to 2023 were finally selected. These were calculated according to the year of publication with a continuous increase (excluding 2012 and 2013) and R2 = 0.9295. Generally, in orthognathic dentistry and maxillofacial surgery, AI and ML have gained popularity over the past few decades. When we included the keywords "planning in maxillofacial surgery" and "planning in orthognathic surgery", the number significantly increased to 7535 publications. The first publication appeared in 1965, with an increasing trend (excluding 2014-2018), with an R2 value of 0.8642. These technologies have been found to be useful in diagnosis and treatment planning in head and neck surgical oncology, cosmetic and aesthetic surgery, and oral pathology. In orthognathic surgery, they have been utilized for diagnosis, treatment planning, assessment of treatment needs, and cephalometric analyses, among other applications. This review confirms that the current use of AI and ML in maxillofacial surgery is focused mainly on evaluating digital diagnostic methods, especially radiology, treatment plans, and postoperative results. However, as these technologies become integrated into maxillofacial surgery and robotic surgery in the head and neck region, it is expected that they will be gradually utilized to plan and comprehensively evaluate the success of maxillofacial surgeries.

Fully digital workflow for ear defect rehabilitation with an immediate implant-retained auricular prosthesis

The fully digital workflow for an immediate implant-retained auricular prosthesis procedure included computer-aided treatment planning, flapless surgery, and the prefabricated auricular prosthesis rehabilitation. This technique also encompassed the presurgery fabrication of the substructure of the implants and the definitive auricular prosthesis to ensure the smooth insertion of the ear prosthesis.

Applications of CAD/CAM Technology for Craniofacial Implants Placement and Manufacturing of Auricular Prostheses-Systematic Review

This systematic review was aimed at gathering the clinical and technical applications of CAD/CAM technology for craniofacial implant placement and processing of auricular prostheses based on clinical cases. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, an electronic data search was performed. Human clinical studies utilizing digital planning, designing, and printing systems for craniofacial implant placement and processing of auricular prostheses for prosthetic rehabilitation of auricular defects were included. Following a data search, a total of 36 clinical human studies were included, which were digitally planned and executed through various virtual software to rehabilitate auricular defects. Preoperative data were collected mainly through computed tomography scans (CT scans) (55 cases); meanwhile, the most common laser scanners were the 3dMDface System (3dMD LLC, Atlanta, Georgia, USA) (6 cases) and the 3 Shape scanner (3 Shape, Copenhagen, Denmark) (6 cases). The most common digital design software are Mimics Software (Mimics Innovation Suite, Materialize, Leuven, Belgium) (18 cases), Freeform software (Freeform, NC, USA) (13 cases), and 3 Shape software (3 Shape, Copenhagen, Denmark) (12 cases). Surgical templates were designed and utilized in 35 cases to place 88 craniofacial implants in auricular defect areas. The most common craniofacial implants were Vistafix craniofacial implants (Entific Medical Systems, Goteborg, Sweden) in 22 cases. A surgical navigation system was used to place 20 craniofacial implants in the mastoid bone. Digital applications of CAD/CAM technology include, but are not limited to, study models, mirrored replicas of intact ears, molds, retentive attachments, customized implants, substructures, and silicone prostheses. The included studies demonstrated a predictable clinical outcome, reduced the patient's visits, and completed the prosthetic rehabilitation in reasonable time and at reasonable cost. However, equipment costs and trained technical staff were highlighted as possible limitations to the use of CAD/CAM systems.

An automated parametric ear model to improve frugal 3D scanning methods for the advanced manufacturing of high-quality prosthetic ears

Ear prostheses are commonly used for restoring aesthetics to those suffering missing or malformed external ears. Traditional fabrication of these prostheses is labour intensive and requires expert skill from a prosthetist. Advanced manufacturing including 3D scanning, modelling and 3D printing has the potential to improve this process, although more work is required before it is ready for routine clinical use. In this paper, we introduce a parametric modelling technique capable of producing high quality 3D models of the human ear from low-fidelity, frugal, patient scans; significantly reducing time, complexity and cost. Our ear model can be tuned to fit the frugal low-fidelity 3D scan through; (a) manual tuning, or (b) our automated particle filter approach. This potentially enables low-cost smartphone photogrammetry-based 3D scanning for high quality personalised 3D printed ear prosthesis. In comparison to standard photogrammetry, our parametric model improves completeness, from (81 ± 5)% to (87 ± 4)%, with only a modest reduction in accuracy, with root mean square error (RMSE) increasing from (1.0 ± 0.2) mm to (1.5 ± 0.2) mm (relative to metrology rated reference 3D scans, n = 14). Despite this reduction in the RMS accuracy, our parametric model improves the overall quality, realism, and smoothness. Our automated particle filter method differs only modestly compared to manual adjustments. Overall, our parametric ear model can significantly improve quality, smoothness and completeness of 3D models produced from 30-photograph photogrammetry. This enables frugal high-quality 3D ear models to be produced for use in the advanced manufacturing of ear prostheses.

Evaluation of the accuracy of digital and conventional implant-level impression techniques for maxillofacial prosthesis

Objectives

This study aims to evaluate the accuracy of digital impression making based on trueness and precision measurements of dental implants placed in maxillofacial lesions to produce Maxillofacial prosthesis substructures.

Methods

Two intra-oral scanners (Trios 3 and CS 3700) and one Desktop scanner (open technology) were examined in this study. A Model of a patient with a lesion in the ear region was created as a reference. The reference model was scanned by each scanner 10 times. Standard Tessellation Language files were provided from each scanner and were examined in terms of Trueness and Precision aspects.

Results

In Distance 1, in the one-way analysis of variance test, there was a significant difference between the three scanners. The Trios group has less deviation than the Open Technology group (P = 0.015) compared with the CareStream (CS) group that showed more deviation (P < 0.000). There is a statistically significant difference in distance 2 among scanners. The Trios group showed more deviation as compared with the Open Technology group (P < 0.000). While this deviation is not statistically significant compared with the CS group (P = 0.0907). Open Technology Group compared with the CS group also has less deviation in distance 2, which has been statistically significant (P < 0.000). The preparation of a precise model of maxillofacial lesions is still difficult for some Intraoral scanners.

Conclusion

There were significant statistical differences in Trueness and Precision among scanners. Used scanners can be applied as an alternative to conventional impression methods.

Evaluation of accuracy of photogrammetry with 3D scanning and conventional impression method for craniomaxillofacial defects using a software analysis

BACKGROUND

Facial mutilation and deformities can be caused by cancer, tumours, injuries, infections, and inherited or acquired deformities and has the potential to degrade one's quality of life by interfering with fundamental tasks like communication, breathing, feeding, and aesthetics. Depending on the type of defect, producing maxillofacial prostheses for the rehabilitation of patients with various defects can be challenging and complex. The prosthesis is used to replace missing or damaged parts of the cranium and face, like the nose, auricle, orbit, and surrounding tissues, as well as missing areas of soft and hard tissue, with the primary goal of increasing the patient's quality of life by rehabilitating oral functions such as speech, swallowing, and mastication. Traditional maxillofacial prosthesis impression and fabrication processes include a number of complicated steps that are costly, time-consuming, and uncomfortable for the patient. These rely on the knowledge of the maxillofacial team, dental clinicians, and maxillofacial technician. The foundation of the impression is the keystone for creating a prosthesis. However, this is the most time-consuming and difficult chair-side operation in maxillofacial prosthesis manufacturing since it requires prolonged interaction with the patient. The field of prosthesis fabrication is being transformed by the digital revolution. Digital technology allows for more accurate impression data to be gathered in less time (3 to 5 min) than traditional methods, lowering patient anxiety. Digital impressions eliminate the need for messy impression materials and provide patients with a more pleasant experience. This method bypasses the procedure of traditional gypsum model fabrication. This eliminates the disparity caused by a dimensional distortion of the impression material and gypsum setting expansion. Traditional dental impression processes leave enough room for errors, such as voids or flaws, air bubbles, or deformities, while current technology for prosthesis planning has emerged as an alternative means to improve patient acceptability and pleasure, not only because the end result is a precisely fitted restoration but also because the chair-side adjustments required are reduced. The most frequent approaches for creating 3D virtual models are the following. To begin, 3D scanning is employed, in which the subjects are scanned in three dimensions, and the point cloud data is used to create a virtual digital model.

METHODS

It will be a hospital-based randomised control trial, carried out at the Department of Prosthodontics, Sharad Pawar Dental College, Sawangi (Meghe), Wardha, a part of Datta Meghe Institute of Medical Sciences (Deemed University). A total of 45 patients will be selected from the outpatient department (OPD) of the Department of Prosthodontics. All the patients will be provided written consent before their participation in the study.

METHODOLOGY

1. Patient screening will be done, and the patient will be allocated to three techniques that are the conventional manual method, photogrammetry method, and 3D scanning in a randomised manner 2. The impression of the defect will be recorded by conventional manual method, photogrammetry method, and 3D scanning 3. The defect will be modelled in three ways: first is as per the manual dimension taken on the patient, second is the organisation of photographic image taken with lab standards and third is plotting of point cloud data to generate the virtual 3D model 4. For photogrammetric prosthesis design, finite photos/images will be taken at multiple angles to model the 3D virtual design. With the use of minimum photographs, the 3D modelling can be performed by using freeware, and a mould is obtained 5. The CAD software was used to design the prosthesis, and the final negative mould can be printed using additive manufacturing 6. The mould fabricated by all three methods will be analysed by a software using reverse engineering technology Study design: Randomised control trial Duration: 2 years Sample size: 45 patients DISCUSSION: Rodrigo Salazar-Gamarra1, Rosemary Seelaus, and Jorge Vicente Lopes da Silva et al., in the year 2016, discussed, as part of a method for manufacturing face prostheses utilising a mobile device, free software, and a photo capture protocol, that 2D captures of the anatomy of a patient with a facial defect were converted into a 3D model using monoscopic photogrammetry and a mobile device. The visual and technical integrity of the resulting digital models was assessed. The technological approach and models that resulted were thoroughly explained and evaluated for technical and clinical value. Marta Revilla-León, Wael Att, and Dr Med Dent et al. (2020) used a coordinate measuring equipment which was used to assess the accuracy of complete arch implant impression processes utilising conventional, photogrammetry, and intraoral scanning. Corina Marilena Cristache and Ioana Tudor Liliana Moraru et al. in the year 2021 provided an update on defect data acquisition, editing, and design using open-source and commercially available software in digital workflow in maxillofacial prosthodontics. This research looked at randomised clinical trials, case reports, case series, technical comments, letters to the editor, and reviews involving humans that were written in English and included detailed information on data acquisition, data processing software, and maxillofacial prosthetic part design.

TRIAL REGISTRATION

CTRI/2022/08/044524. Registered on September 16, 2022.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Ultrasound Imaging Offers Promising Alternative to Create 3-D Models for Personalised Auricular Implants

Three-dimensional imaging and advanced manufacturing are being applied in health care research to create novel diagnostic and surgical planning methods, as well as personalised treatments and implants. For ear reconstruction, where a cartilage-shaped implant is embedded underneath the skin to re-create shape and form, volumetric imaging and segmentation processing to capture patient anatomy are particularly challenging. Here, we introduce 3-D ultrasound (US) as an available option for imaging the external ear and underlying auricular cartilage structure, and compare it with computed tomography (CT) and magnetic resonance imaging (MRI) against micro-CT (µCT) as a high-resolution reference (gold standard). US images were segmented to create 3-D models of the auricular cartilage and compared against models generated from µCT to assess accuracy. We found that CT was significantly less accurate than the other methods (root mean square [RMS]: 1.30 ± 0.5 mm) and had the least contrast between tissues. There was no significant difference between MRI (RMS: 0.69 ± 0.2 mm) and US (0.55 ± 0.1 mm). US was also the least expensive imaging method at half the cost of MRI. These results unveil a novel use of ultrasound imaging that has not been presented before, as well as support its more widespread use in biofabrication as a low-cost imaging technique to create patient-specific 3D models and implants.

The cutting edge of customized surgery: 3D-printed models for patient-specific interventions in otology and auricular management-a systematic review

PURPOSE

3D-printing (three-dimensional printing) is an emerging technology with promising applications for patient-specific interventions. Nonetheless, knowledge on the clinical applicability of 3D-printing in otology and research on its use remains scattered. Understanding these new treatment options is a prerequisite for clinical implementation, which could improve patient outcomes. This review aims to explore current applications of 3D-printed patient-specific otologic interventions, including state of the evidence, strengths, limitations, and future possibilities.

METHODS

Following the PRISMA statement, relevant studies were identified through Pubmed, EMBASE, the Cochrane Library, and Web of Science. Data on the manufacturing process and interventions were extracted by two reviewers. Study quality was assessed using Joanna Briggs Institute's critical appraisal tools.

RESULTS

Screening yielded 590 studies; 63 were found eligible and included for analysis. 3D-printed models were used as guides, templates, implants, and devices. Outer ear interventions comprised 73% of the studies. Overall, optimistic sentiments on 3D-printed models were reported, including increased surgical precision/confidence, faster manufacturing/operation time, and reduced costs/complications. Nevertheless, study quality was low as most studies failed to use relevant objective outcomes, compare new interventions with conventional treatment, and sufficiently describe manufacturing.

CONCLUSION

Several clinical interventions using patient-specific 3D-printing in otology are considered promising. However, it remains unclear whether these interventions actually improve patient outcomes due to lack of comparison with conventional methods and low levels of evidence. Further, the reproducibility of the 3D-printed interventions is compromised by insufficient reporting. Future efforts should focus on objective, comparative outcomes evaluated in large-scale studies.

Fabricating nasal prostheses using four-dimensional facial expression models

Purpose Patients with facial prostheses face challenges such as maintenance of the prosthesis in place, especially around the margins, because of movement of surrounding facial skin. Conventional facial prostheses are fabricated on stationary models based on two points: neutral expression and smiling expression. We developed four-dimensional (4D) facial expression models which shape facial expressions that change over several points in time using a morphing technique. We fabricated facial prostheses using 4D models and evaluated their accuracy and fit compared with prostheses generated with the two-expression technique.Methods Seven patients with nasal defects or nasal deformities participated in this study. Facial expression morphing prostheses were fabricated based on the 4D scanned data of each patient, using five points between neutral expression (0%) and smiling (100%). Five nasal prostheses, one for each point, were evaluated in each patient objectively and subjectively for accuracy and fit.Results On subjective evaluation, the nasal prostheses fabricated using the 4D facial expression models had better marginal sealing over the range from the neutral expression to smiling, and showed better attachment during facial movement on objective evaluation.Conclusions Facial prostheses fabricated using 4D facial expression models provided better marginal sealing than those fabricated using conventional two-point modeling.

Frugal 3D scanning using smartphones provides an accessible framework for capturing the external ear

Three-dimensional (3D) scanning technologies, such as medical imaging and surface scanning, have important applications for capturing patient anatomy to create personalised prosthetics. Digital approaches for capturing anatomical detail as opposed to traditional, invasive impression techniques significantly reduces turnaround times and lower production costs while still maintaining the high aesthetic quality of the end product. While previous case studies utilise expensive 3D scanning and modelling frameworks, their clinical translation is limited due to high equipment costs. In this study, we develop and validate a low-cost framework for clinical 3D scanning of the external ear using photogrammetry and a smartphone camera. We recruited five novice operators who watched an instructional video before scanning 20 healthy adult participant ears who did not have microtia. Our results show that the smartphone-based photogrammetry methodology produces 3D scans of the external ear that were accurate to (1.5 ± 0.4) mm and were (71 ± 14) % complete compared with those from a gold standard reference scanner, with no significant difference observed between operators. A moderate to strong interrater reliability was determined for all novice operators, suggesting that all novice operators were able to capture repeatable scans. The development of this smartphone photogrammetry approach has the potential to provide a non-invasive, inexpensive and accessible means to capture patient morphology for use in clinical assessment and personalised device manufacture, specifically for ear prostheses. We also demonstrate that inexperienced operators can rapidly learn and apply smartphone photogrammetry for accurate and reliable scans of the external ear with important applications for future clinical translation.

Biomaterials and 3D printing techniques used in the medical field

An implants' effectiveness depends upon the form of biomaterial used in its manufacture. A suitable material for implants should be biocompatible, sterile, mechanically stable and simple to shape. 3D printing technologies have been breaking new ground in the medical and medical industries in order to build patient-specific devices embedded in bioactive drugs, cells and proteins. Widespread use in medical 3D printing is a broad range of biomaterials including metals, ceramics, polymers and composites. Continuous work and developments in biomaterials used in 3D printing have contributed to significant growth of 3D printing applications in the production of personalised joints, prostheses, medication delivery system and 3D tissue engineering and regenerative medicine scaffolds. The present analysis focuses on the biomaterials used for therapeutic applications in different 3D printing technologies. Many specific forms of medical 3D printing technology are explored in depth, including fused deposition modelling, extrusion-based bioprinting, inkjet and poly-jet printing processes, their therapeutic uses, various types of biomaterial used today and the major shortcoming , are being studied in depth.

Digital Workflow in Maxillofacial Prosthodontics—An Update on Defect Data Acquisition, Editing and Design Using Open-Source and Commercial Available Software

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.

Accuracy Evaluation of a Three-Dimensional Model Generated from Patient-Specific Monocular Video Data for Maxillofacial Prosthetic Rehabilitation: A Pilot Study

PURPOSE

To evaluate if the combination of a monoscopic photogrammetry technique and smartphone-recorded monocular video data could be appropriately applied to maxillofacial prosthesis fabrication.

MATERIALS AND METHODS

Smartphone video and laser scanning data were recorded for five healthy volunteers (24.1 ± 0.7 years). Three-dimensional (3D) facial models were generated using photogrammetry software and a laser scanner. Smartphone-recorded video data were used to generate a photogrammetric 3D model. The videos were recorded at two resolutions: 1080 × 1920 (high resolution) and 720 × 1280 pixels (low resolution). The lengths of five nasal component parts (nose height, nasal dorsum length, nasal column length, nasal ala length, and nose breadth) were compared in the photogrammetric 3D models (as the test model) and the laser scanned 3D models (as the validation model) using reverse engineering software.

RESULTS

There was a significant difference in the nasal dorsum length between the test model and the validation model (high resolution; 95% confidence interval, 2.05-5.07, Low resolution; confidence interval, 2.19-5.69). In contrast to the nasal dorsum length, there were no significant differences in nose height, nose breadth, nasal ala length, and nasal column length.

CONCLUSION

Using smartphone-recorded video data and a photogrammetry technique may be a promising technique to apply in the maxillofacial prosthetic rehabilitation workflow.

An advanced prosthetic manufacturing framework for economic personalised ear prostheses

Craniofacial prostheses are commonly used to restore aesthetics for those suffering from malformed, damaged, or missing tissue. Traditional fabrication is costly, uncomfortable for the patient, and laborious; involving several hours of hand-crafting by a prosthetist, with the results highly dependent on their skill level. In this paper, we present an advanced manufacturing framework employing three-dimensional scanning, computer-aided design, and computer-aided manufacturing to efficiently fabricate patient-specific ear prostheses. Three-dimensional scans were taken of ears of six participants using a structured light scanner. These were processed using software to model the prostheses and 3-part negative moulds, which were fabricated on a low-cost desktop 3D printer, and cast with silicone to produce ear prostheses. The average cost was approximately $3 for consumables and $116 for 2 h of labour. An injection method with smoothed 3D printed ABS moulds was also developed at a cost of approximately $155 for consumables and labour. This contrasts with traditional hand-crafted prostheses which range from $2,000 to $7,000 and take around 14 to 15 h of labour. This advanced manufacturing framework provides potential for non-invasive, low cost, and high-accuracy alternative to current techniques, is easily translatable to other prostheses, and has potential for further cost reduction.

Implementation of 3D technologies in the workflow of auricular prosthetics: A method using optical scanning and stereolithography 3D printing

The fabrication of auricular prostheses is traditionally time consuming, and the definitive esthetic appearance is highly skill dependent. A method of creating the wax pattern for an auricular prosthesis by using optical scanning and 3D printing is described. A digital scan of the unaffected ear is used for computer-aided design and manufacturing of a mold for casting the wax pattern of the prosthesis. The process is efficient and increases the predictability of the esthetic outcome.

Use of Laser Systems in Orthodontics

Laser systems have been used in the practice of dentistry for >35 years. Laser systems have so many advantages, such as increase patient cooperation, reduce the duration of treatment time, and help the orthodontists to enhance the design of a patient's smile to improve treatment efficacy, and the success of orthodontic treatments can also be improved by diminishing the orthodontic pain and the discomfort of the patients. Laser systems also have some disadvantages, such as cost, large space requirements for some types, and high-risk potential for physician and patient if not used at the appropriate wavelength and power density, that is why before incorporating lasers into clinical practice, the physician must fully understand the basic science, safety protocol, and risks associated with them. Lasers have many applications in orthodontics, including accelerating tooth movement, bonding and debonding processes, pain reduction, bone regeneration, etching procedures, increase mini-implant stability, soft tissue procedures (gingivectomy, frenectomy, operculectomy, papilla flattening, uncovering temporary anchorage devices, ablation of aphthous ulcerations, and exposure of impacted teeth), fiberotomy, scanning systems, and welding procedures. In reviewing the literature on the use of laser in orthodontics, many studies have been conducted. The purpose of the present study was to give information about the use of laser in the field of orthodontics, the effects of laser during the postoperative period, and its advantages and disadvantages and to provide general information about the requirements to be considered during the use of laser.

Advancements in Soft-Tissue Prosthetics Part B: The Chemistry of Imitating Life

Each year, congenital defects, trauma or cancer often results in considerable physical disfigurement for many people worldwide. This adversely impacts their psychological, social and economic outlook, leading to poor life experiences and negative health outcomes. In many cases of soft tissue disfigurement, highly personalized prostheses are available to restore both aesthetics and function. As discussed in part A of this review, key to the success of any soft tissue prosthetic is the fundamental properties of the materials. This determines the maximum attainable level of aesthetics, attachment mechanisms, fabrication complexity, cost, and robustness. Since the early-mid 20th century, polymers have completely replaced natural materials in prosthetics, with advances in both material properties and fabrication techniques leading to significantly improved capabilities. In part A, we discussed the history of polymers in prosthetics, their ideal properties, and the application of polymers in prostheses for the ear, nose, eye, breast and finger. We also reviewed the latest developments in advanced manufacturing and 3D printing, including different fabrication technologies and new and upcoming materials. In this review, Part B, we detail the chemistry of the most commonly used synthetic polymers in soft tissue prosthetics; silicone, acrylic resin, vinyl polymer, and polyurethane elastomer. For each polymer, we briefly discuss their history before detailing their chemistry and fabrication processes. We also discuss degradation of the polymer in the context of their application in prosthetics, including time and weathering, the impact of skin secretions, microbial growth and cleaning and disinfecting. Although advanced manufacturing promises new fabrication capabilities using exotic synthetic polymers with programmable material properties, silicones and acrylics remain the most commonly used materials in prosthetics today. As research in this field progresses, development of new variations and fabrication techniques based on these synthetic polymers will lead to even better and more robust soft tissue prosthetics, with improved life-like aesthetics and lower cost manufacturing.

Advancements in Soft-Tissue Prosthetics Part A: The Art of Imitating Life

Physical disfigurement due to congenital defects, trauma, or cancer causes considerable distress and physical impairment for millions of people worldwide; impacting their economic, psychological and social wellbeing. Since 3000 B.C., prosthetic devices have been used to address these issues by restoring both aesthetics and utility to those with disfigurement. Internationally, academic and industry researchers are constantly developing new materials and manufacturing techniques to provide higher quality and lower cost prostheses to those people who need them. New advanced technologies including 3D imaging, modeling, and printing are revolutionizing the way prostheses are now made. These new approaches are disrupting the traditional and manual art form of prosthetic production which are laborious and costly and are being replaced by more precise and quantitative processes which enable the rapid, low cost production of patient-specific prostheses. In this two part review, we provide a comprehensive report of past, present and emerging soft-tissue prosthetic materials and manufacturing techniques. In this review, part A, we examine, historically, the ideal properts of a polymeric material when applied in soft-tissue prosthetics. We also detail new research approaches to target specific tissues which commonly require aesthetic restoration (e.g. ear, nose and eyes) and discuss both traditional and advanced fabrication methods, from hand-crafted impression based approaches to advanced manufactured prosthetics. We discuss the chemistry and related details of most significant synthetic polymers used in soft-tissue prosthetics in Part B. As advanced manufacturing transitions from research into practice, the five millennia history of prosthetics enters a new age of economic, personalized, advanced soft tissue prosthetics and with this comes significantly improved quality of life for the people affected by tissue loss.

The mussel-inspired assisted apatite mineralized on PolyJet material for artificial bone scaffold

With the development of three-dimensional (3D) printing, many commercial 3D printing materials have been applied in the fields of biomedicine and medical. MED610 is a clear, biocompatible PolyJet material that is medically certified for bodily contact. In this study, the polydopamine (PDA)/hydroxyapatite (HA) coating was added to the printed MED610 objects to evaluate its physical properties, cell proliferation, cell morphology, and alkaline phosphatase expression level. The results show that the PDA/HA coating helps printed objects to enhance the hardness, biocompatibility, and osteogenic differentiation potential. We expect that PDA/HA coatings contribute to the applicability of MED610 in biomedical and medical applications.

Accuracy of capturing oncology facial defects with multimodal image fusion versus laser scanning

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.

Digital Workflow of Auricular Rehabilitation: A Technical Report Using an Intraoral Scanner

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.

Ear Reconstruction Simulation: From Handcrafting to 3D Printing

Microtia is a congenital malformation affecting one in 5000 individuals and is characterized by physical deformity or absence of the outer ear. Nowadays, surgical reconstruction with autologous tissue is the most common clinical practice. The procedure requires a high level of manual and artistic techniques of a surgeon in carving and sculpting of harvested costal cartilage of the patient to recreate an auricular framework to insert within a skin pocket obtained at the malformed ear region. The aesthetic outcomes of the surgery are highly dependent on the experience of the surgeon performing the surgery. For this reason, surgeons need simulators to acquire adequate technical skills out of the surgery room without compromising the aesthetic appearance of the patient. The current paper aims to describe and analyze the different materials and methods adopted during the history of autologous ear reconstruction (AER) simulation to train surgeons by practice on geometrically and mechanically accurate physical replicas. Recent advances in 3D modelling software and manufacturing technologies to increase the effectiveness of AER simulators are particularly described to provide more recent outcomes.

Personalized 3D kidney model produced by rapid prototyping method and its usefulness in clinical applications

BACKGROUND

Three-dimensional (3D) printing has been introduced as a novel technique to produce 3D objects. We tried to evaluate the clinical usefulness of 3D-printed renal model in performing partial nephrectomy (PN) and also in the education of medical students.

MATERIALS AND METHODS

We prospectively produced personalized renal models using 3D-printing methods from preoperative computed tomography (CT) images in a total of 10 patients. Two different groups (urologist and student group) appraised the clinical usefulness of 3D-renal models by answering questionnaires.

RESULTS

After application of 3D renal models, the urologist group gave highly positive responses in asking clinical usefulness of 3D-model among PN (understanding personal anatomy: 8.9 / 10, preoperative surgical planning: 8.2 / 10, intraoperative tumor localization: 8.4 / 10, plan for further utilization in future: 8.3 / 10, clinical usefulness in complete endophytic mass: 9.5 / 10). The student group located each renal tumor correctly in 47.3% when they solely interpreted the CT images. After the introduction of 3D-models, the rate of correct answers was significantly elevated to 70.0% (p < 0.001). The subjective difficulty level in localizing renal tumor was also significantly low (52% versus 27%, p < 0.001) when they utilized 3D-models.

CONCLUSION

The personalized 3D renal model was revealed to significantly enhance the understanding of correct renal anatomy in patients with renal tumors in both urologist and student groups. These models can be useful for establishing the perioperative planning and also education program for medical students.

Development of three-dimensional facial expression models using morphing methods for fabricating facial prostheses

PURPOSE

It is essential to fabricate a best-fit three-dimensional (3D) facial prosthesis model capable of facial expressions. In order for the facial prosthesis to remain in position, especially around marginal areas subject to movement, a new method of making 3D facial expression models using time-series data allowing changes in facial expression by morphing technique was developed.

METHODS

Seven normal subjects and seven patients with nasal defects or nasal deformities participated in this study. Three distinct facial expressions (i.e., a neutral expression, smiled, and open mouthed) were digitally acquired with a facial scanner. Prepared template models were transformed to homologous models, which can represent the form as shape data with the same number of point cloud data of the same topology referring to the scanning data. Finally, 3D facial expression models were completed by generating a morphing image based on two sets of homologous models, and the accuracy of the homologous models of all subjects was evaluated.

RESULTS

3D facial expression models of both normal subjects and patients with nasal defects were successfully generated. No significant differences in shape between the scanned models and homologous models were shown.

CONCLUSIONS

The high accuracy of this 3D facial expression model in both normal subjects and patients suggests its use for fabricating facial prostheses.

Maxillofacial prostheses challenges in resource constrained regions

BACKGROUND

This study reviewed the current state of maxillofacial rehabilitation in resource-limited nations.

METHOD

A rigorous literature review was undertaken using several technical and clinical databases using a variety of key words pertinent to maxillofacial prosthetic rehabilitation and resource-limited areas. In addition, interviews were conducted with researchers, clinicians and prosthetists that had direct experience of volunteering or working in resource-limited countries.

RESULTS

Results from the review and interviews suggest rehabilitating patients in resource-limited countries remains challenging and efforts to improve the situation requires a multifactorial approach.

CONCLUSIONS

In conclusion, public health awareness programmes to reduce the causation of injuries and bespoke maxillofacial prosthetics training programmes to suit these countries, as opposed to attempting to replicate Western training programmes. It is also possible that usage of locally sourced and cheaper materials and the use of low-cost technologies could greatly improve maxillofacial rehabilitation efforts in these localities. Implications for Rehabilitation More information and support needs to be provided to maxillofacial defect/injuries patients and to their families or guardians in a culturally sensitive manner by governments. The health needs, economic and psychological needs of the patients need to be taken into account during the rehabilitation process by clinicians and healthcare organizations. The possibility of developing training programs to suit these resource limited countries and not necessarily follow conventional fabrication methods must be looked into further by educational entities.

[Bone anchored auricular prosthesis for patients with grade III microtia]

The aim of the study was to assess the effectivity of auricular prosthesis on intraosseous implants in patient with grade III microtia. The study included 7 patients (5 males and 2 females) aged 18 to 45 years with hemifacial microsomia and grade III microtia operated in Central Research Institute of Dentistry and Maxillofacial Surgery in 2013-2016. Number and position of intraosseous implants was determined by reverse planning based on CT representing hard and soft facial structures. Patients were followed-up for 6-36 months. Good esthetic results were obtained by minimally invasive surgical procedure and short post-op rehabilitation. However these results required meticulous virtual planning and manufacturing of surgical template. The described method promotes very fast medical and social rehabilitation of patients with severe microtia.

An innovative method of ocular prosthesis fabrication by bio-CAD and rapid 3-D printing technology: A pilot study

Ocular prosthesis is either a readymade stock shell or custom made prosthesis (CMP). Presently, there is no other technology available, which is either superior or even comparable to the conventional CMP. The present study was designed to fabricate ocular prosthesis using computer aided design (CAD) and rapid manufacturing (RM) technology and to compare it with custom made prosthesis (CMP). The ocular prosthesis prepared by CAD was compared with conventional CMP in terms of time taken for fabrication, weight, cosmesis, comfort, and motility. Two eyes of two patients were included. Computerized tomography scan of wax model of socket was converted into three dimensional format using Materialize Interactive Medical Image Control System (MIMICS)software and further refined. This was given as an input to rapid manufacturing machine (Polyjet 3-D printer). The final painting on prototype was done by an ocularist. The average effective time required for fabrication of CAD prosthesis was 2.5 hours; and weight 2.9 grams. The same for CMP were 10 hours; and 4.4 grams. CAD prosthesis was more comfortable for both the patients. The study demonstrates the first ever attempt of fabricating a complete ocular prosthesis using CAD and rapid manufacturing and comparing it with conventional CMP. This prosthesis takes lesser time for fabrication, and is more comfortable. Studies with larger sample size will be required to further validate this technique.

CAD/CAM-Assisted Auricular Prosthesis Fabrication for a Quick, Precise, and More Retentive Outcome: A Clinical Report

Auricular defects comprise a large proportion of maxillofacial deformities. Most patients with acquired deformities have psychosocial ineptness and seek cosmetic rehabilitation. Although minor defects can be corrected surgically, extensive deformities are difficult to reconstruct with plastic surgery. Contrary to that, prosthetic restoration can provide excellent esthetic results. The conventional methods of maxillofacial prosthesis fabrication are time consuming and the outcome depends on the technician's skill. The advent of CAD/CAM technology in the field of dentistry has brought enormous improvement in the quality of health care provided. In the past decade, several methods have been described employing CAD/CAM techniques for the cosmetic rehabilitation of auricular defects. This clinical report details the integration of multiple digital technologies of CT scanning, computer aided design, and rapid prototyping to construct an ear prosthesis with limited number of appointments.

A Simple Technique for Placing Extraoral Implants at an Optimal Position in Orbital Defects

Translucent acrylic templates have been used to indicate implant positions for implant-retained extraoral prostheses; however, this procedure can be challenging, as the acrylic templates have to be positioned onto reflected skin flaps. The fabrication of an acrylic-based colorless template or duplicating an existing prosthesis can facilitate the location of extraoral implants. Spots can be created on templates to indicate the optimal position of the implants. Afterward, punching the skin to the bone with a very thick sharp needle or a small sharp bur will mark the desired implant position on the bone before reflecting the skin.

Developing an Ear Prosthesis Fabricated in Polyvinylidene Fluoride by a 3D Printer with Sensory Intrinsic Properties of Pressure and Temperature

An ear prosthesis was designed in 3D computer graphics software and fabricated using a 3D printing process of polyvinylidene fluoride (PVDF) for use as a hearing aid. In addition, the prosthesis response to pressure and temperature was observed. Pyroelectric and piezoelectric properties of this ear prosthesis were investigated using an astable multivibrator circuit, as changes in PVDF permittivity were observed according to variations of pressure and temperature. The results show that this prosthesis is reliable for use under different conditions of pressure (0 Pa to 16,350 Pa) and temperature (2 °C to 90 °C). The experimental results show an almost linear and inversely proportional behavior between the stimuli of pressure and temperature with the frequency response. This 3D-printed ear prosthesis is a promising tool and has a great potentiality in the biomedical engineering field because of its ability to generate an electrical potential proportional to pressure and temperature, and it is the first time that such a device has been processed by the additive manufacturing process (3D printing). More work needs to be carried out to improve the performance, such as electrical stimulation of the nervous system, thereby extending the purpose of a prosthesis to the area of sensory perception.

Innovative Approach for Interim Facial Prosthesis Using Digital Technology

Despite the important role of facial prosthetic treatment in the rehabilitation of head and neck cancer patients, delay in its implementation can be unavoidable, preventing patients from receiving a prompt facial prosthesis and resuming a normal social life. Here, we introduce an innovative method for the fabrication of an interim facial prosthesis. Using a 3D modeling system, we simplified the fabrication method and used a titanium reconstruction plate for facial prosthesis retention. The patient received the facial prosthesis immediately after surgery and resumed a normal social life earlier than is typically observed with conventional facial prosthetic treatment.

Rapid prototyping-assisted maxillofacial reconstruction

Rapid prototyping (RP) technologies have found many uses in dentistry, and especially oral and maxillofacial surgery, due to its ability to promote product development while at the same time reducing cost and depositing a part of any degree of complexity theoretically. This paper provides an overview of RP technologies for maxillofacial reconstruction covering both fundamentals and applications of the technologies. Key fundamentals of RP technologies involving the history, characteristics, and principles are reviewed. A number of RP applications to the main fields of oral and maxillofacial surgery, including restoration of maxillofacial deformities and defects, reduction of functional bone tissues, correction of dento-maxillofacial deformities, and fabrication of maxillofacial prostheses, are discussed. The most remarkable challenges for development of RP-assisted maxillofacial surgery and promising solutions are also elaborated.

A new method for fabricating orbital prosthesis with a CAD/CAM negative mold

The challenge of fabricating an orbital prosthesis is how to position the iris and pupil properly. Computer simulation can be a more effective and simpler approach to measuring and evaluating these features than the conventional method. However, transferring the optimal position of the iris determined in the virtual design procedure to the real definitive prosthesis can be difficult. The purpose of this article is to demonstrate a method of fabricating an orbital prosthesis with a negative mold designed and produced by a computer-aided design and computer-aided manufacturing technique. With this method, the iris can be designed in the most favorable position, and this position can be transferred to the silicone prosthesis correctly.

Prosthetic Rehabilitation of Partial Ear Defect: 2 Case Reports

The loss or absence of an auricle may result from trauma, disease or congenital anomalies and causes a considerable aesthetic problem. If the deformity involves the external auditory canal, it can affect hearing. This case report describes the surgical and prosthetic treatment of two patients with partial defects of their right external ears from different causes. Implant-retained auricular prostheses fabricated from heat-temperature-vulcanised silicone were used in both the cases; they were designed to be harmonious with the remaining tissues. The patients experienced improved retention, aesthetics, hearing and quality of life with these prostheses. During the approximately 3 year follow-up, both the prostheses were re-fabricated once; however, problems related to implant stability and peri-implant tissue health were not encountered.

Planning implant positions for an auricular prosthesis with digital data

The esthetic result of an auricular prosthesis is influenced by the position of the prosthesis incorporating the implants. The entire surface of the patient's head is captured by means of a conventional computed tomography (CT). The digital data are used to mirror the contralateral unimpaired ear for restoration of the impaired side. The virtual ear is integrated into a template covering the auricular defect and indexed to the nasal area with computer-aided technology (CAD/CAM). This virtual template is converted into an acrylic resin template. With that the surgeon and the anaplastologist should determine the optimal implant position of the auricular prosthesis.

Prototyping for surgical and prosthetic treatment

Techniques of rapid prototyping were introduced in the 1980s in the field of engineering for the fabrication of a solid model based on a computed file. After its introduction in the biomedical field, several applications were raised for the fabrication of models to ease surgical planning and simulation in implantology, neurosurgery, and orthopedics, as well as for the fabrication of maxillofacial prostheses. Hence, the literature has described the evolution of rapid prototyping technique in health care, which allowed easier technique, improved surgical results, and fabrication of maxillofacial prostheses. Accordingly, a literature review on MEDLINE (PubMed) database was conducted using the keywords rapid prototyping, surgical planning, and maxillofacial prostheses and based on articles published from 1981 to 2010. After reading the titles and abstracts of the articles, 50 studies were selected owing to their correlations with the aim of the current study. Several studies show that the prototypes have been used in different dental-medical areas such as maxillofacial and craniofacial surgery; implantology; neurosurgery; orthopedics; scaffolds of ceramic, polymeric, and metallic materials; and fabrication of personalized maxillofacial prostheses. Therefore, prototyping has been an indispensable tool in several studies and helpful for surgical planning and fabrication of prostheses and implants.

Mirror imaging and preshaped titanium plates in the treatment of unilateral malar and zygomatic arch fractures

OBJECTIVE

The aim of this study is to discuss the application of mirror imaging and preshaped titanium plates in the treatment of unilateral malar and zygomatic arch fractures.

STUDY DESIGN

Four patients with unilateral malar and zygomatic arch fractures were included in this study. All patients underwent preoperative CT scan. CT data were processed with Surgicase. Two 3D skull models were reconstructed using a rapid prototyping device. The first model was the original model obtained from CT scanning; the other model was obtained by mirroring the unaffected side onto the fractured side. Simulation surgery was performed on the first model. For the second model, titanium plates were shaped in advance and a resinous guide plate was created to guide surgical reduction. When using the resinous guide plates, 4 patients' fractures were reduced and fixed with preshaped titanium plates. The pre- and postoperative displacement of zygomatic markers were analyzed in Surgicase.

RESULTS

According to the measurement of fracture displacements, the facial asymmetry of all 4 patients was greatly improved at the 1-month follow-up.

CONCLUSIONS

Mirror imaging and preshaped titanium plates are viable choices for the treatment of unilateral malar and zygomatic arch fractures. Combined use of these techniques can improve facial symmetry.

CAD/CAM bilateral ear prostheses construction for Treacher Collins syndrome patients using laser scanning and rapid prototyping

Ear defects in patients affected by Treacher Collins syndrome necessitate the replacement of the existing anatomic residuals of the ears with custom-made prostheses. This paper describes a multidisciplinary protocol involving both medicine and computer-aided design/computer-aided manufacturing for manufacturing ear prostheses. Using innovative prototyping technologies together with conventional silicone processing procedures, a step-by-step procedure is presented. The complete workflow includes laser scanning of the defective regions of a patient's face, the use of 3D anatomic models from an ear digital library and rapid prototyping of both substructures for bar anchoring and moulds for silicone processing.