3D Printing-Encompassing the Facets of Dentistry

Three-Dimensional Tooth Models with Pulp Cavity Enhance Dental Anatomy Education

Dental anatomy is an integrated, core fundamental dental course, which prepares students for all future clinical dental courses. This study aimed to build up an online dental learning platform of micro-computed tomography-based three-dimensional (3D) tooth models with pulp cavity, and to further evaluate its effectiveness for dental anatomy education using a cohort study. First, ninety-six extracted permanent teeth were scanned by micro-computed tomography and the enamel, dentine, and pulp cavity of each was distinguished by different grey-scale intensities using Mimics software. Three-dimensional images allowed further discrimination and insights into permanent three-rooted premolars, central tip, and dental diseases including deep caries and wedge-shaped defects. Furthermore, a second mesiobuccal canal (MB2) in maxillary permanent molar teeth and Vertucci type III root canal configuration in mandibular anterior teeth could be detected using the 3D analytical tool. A digitized 3D tooth model learning platform was implemented. Last, two groups of dental students were assessed to evaluate the effect of 3D models on dental anatomy education. Participants in the Digital group were allowed to use the online dental learning platform freely after class, while the participants in the Traditional group were not. Assessment quizzes showed that participants' scores improved in the Digital group with the use of the learning platform compared with scores in the Traditional group. A questionnaire survey indicated that the participants had a positive attitude toward the 3D models. Thus, adding digital 3D resources to a traditional curriculum may have a positive effect on academic achievements.

3D Printing Improve the Effectiveness of Fracture Teaching and Medical Learning: A Comprehensive Scientometric Assessment and Future Perspectives

Fractures of complex body parts are often serious and difficult to handle, and they have high technical and training requirements. However, the realistic situation is that there are few opportunities for the junior residents, trainee doctors, and especially medical students to contact enough clinical practice and see such fracture patients. Fortunately, with the rapid development and continuous progress of 3D printing and related technologies, this situation has gradually gotten better and better. In this research, we confirmed that 3D printing technology could improve the effectiveness of fracture teaching and medical learning from multiple dimensions. We comprehensively screened and assessed 223 papers from the Web of Science (WoS) Core Collection on October 3, 2021, with “((3D) AND ((printing) OR (printed)) AND (fracture)) AND ((education) OR (training) OR (teaching))” as the retrieval strategy. Additionally, we used the VOSviewer software to analyze the keywords and countries and the organizations of the publications, then a series of scientometric and visualized analyses were made based on the retrieval results. Afterward, multiple databases were retrieved according to our selection criteria, we selected eight studies for the extensive literature analysis. The extracted data contained information of authors, problems solved, participants, methods, assessments, results, and benefits/limitations. These intuitive and in-depth analyses further confirmed and appraised the advantages of 3D printing in complex fracture models more objectively. In conclusion, 3D printing could improve the effectiveness and extension of fracture teaching, as well as medical learning, by providing the powerful interaction with 3D effect, wakening students learning interest, and allowing the junior residents, trainee doctors to have as realistic a virtual practice experience as possible. Through this research, it is expected that more researchers could be attracted to conduct more comprehensive and thorough studies on the application of 3D printing for training and educational propose, to promote the development of 3D technology-based medical education practice and further deepen the reform of medical education and improve the quality of fracture education and learning.

Implementation Challenges of 3D Printing in Prosthodontics: A Ranking-Type Delphi

The reduction in cost and increasing benefits of 3D printing technologies suggest the potential for printing dental prosthetics. However, although 3D printing technologies seem to be promising, their implementation in practice is complicated. To identify and rank the greatest implementation challenges of 3D printing in dental practices, the present study surveys dentists, dental technicians, and 3D printing companies using a ranking-type Delphi study. Our findings imply that a lack of knowledge is the most crucial obstacle to the implementation of 3D printing technologies. The high training effort of staff and the favoring of conventional methods, such as milling, are ranked as the second and third most relevant factors. Investment costs ranked in seventh place, whereas the lack of manufacturing facilities and the obstacle of print duration ranked below average. An inclusive implementation of additive manufacturing could be achieved primarily through the education of dentists and other staff in dental practices. In this manner, production may be managed internally, and the implementation speed may be increased.

Virtual Planning and Rapid 3D Prototyping Surgical Guide for Anterior Crown Lengthening Surgery: A Clinical Case Report

Progress with additive 3D printing is revolutionizing biomaterial manufacturing, including clinical dentistry and prosthodontics. Among the several 3D additive printing technologies, stereolithography is very popular as it utilizes light-activated resin for precise resolution. A simplified digital technique was used to fabricate two designs of a surgical guide for crown lengthening. Two cases are presented that utilized digital DICOM files obtained with computed tomography (CT) imaging and processed using four CAD software (Blue Sky Plan, Exocad, Meshmixer and 3D Slicer). The final models were converted to standard tesselation (STL) files and the guides were 3D printed with an additive sterelithography (SLA) printer. The first case was fabricated with a bone model from CBCT data, and the second case was generated with intraoral and wax-up scans alone. Both methods appear to be equally effective compared to using a conventional method of guide frabication. However, proximal bone reduction was a concern with both designs. Digitally fabricated 3D printed surgical guide for crown lengthening has merit and a practical design is needed for future clinical validation. This article is protected by copyright. All rights reserved.

Technical skill training and assessment in dental education

Highly competent clinical practice requires cognitive, psychomotor and affective skills. Therefore, the ultimate goal of dental education is for practitioners to be competent in all of these domains. While many methods have been introduced to assess knowledge and non-technical skills, it is still very difficult for educators to assess technical skill. Assessment methods for technical skills are still not well established because it is very difficult to assure objectivity, validity and fairness. Nonetheless, technical skill is especially important in dental treatments, along with knowledge and attitude. The aim of this review was to summarize the methods of technical skill training in dental education and how they are assessed. This is a literature review. We searched PubMed MEDLINE using terms related to technical skill training and those assessment as of June 2020 and reviewed them. There have been many reports introducing methods of technical skill training and assessment, including the use of digital technology. However, no single assessment method had demonstrated validity of it. Technical skill training is very important in dental education and there are various ways of learning. The validity of current assessment methods is limited; therefore, a combination of several methods may achieve the best results.

Tyrosol-Derived Biodegradable Inks with Tunable Properties for 3D Printing

Three-dimensional (3D) printing has emerged as a valuable tool in medicine over the past few decades. With a growing number of applications using this advanced processing technique, new polymer libraries with varied properties are required. Herein, we investigate tyrosol-based poly(ester-arylate)s as biodegradable inks in fused deposition modeling (FDM). Tyrosol-based polycarbonates and polyesters have proven to be useful biomaterials due to their excellent tunability, nonacidic degradation components, and the ability to be functionalized. Polymers are synthesized by polycondensation between a custom diphenol and commercially available diacids. Thermal properties, degradation rates, and mechanical properties are all tunable based on the diphenol and diacid chosen. Evaluation of material print as it relates to chemical structure, molecular weight, and thermal properties was explored. Higher-molecular-weight polymers greater than 50 kDa exhibit thermal degradation during printing and at some points are too viscous to print. It was determined that polymers with lower processing temperatures and molecular weights were printable regardless of the structure. An exception to this was pHTy6 that was printed at 65 kDa with minimal degradation. This is most likely due to its low melting temperature and, as a result, lower printing temperatures. Additionally, chemical improvements were made to incorporate thiol-alkene click chemistry as a means for postprint curing. Low-molecular-weight pHTy6 was end-capped with alkene functionality. This material was then formulated with either a dithiol for chain extension or tetrathiol for cross-linking. Scaffolds were cured after printing for 5, 15, 30 and 60 min intervals where longer cure times resulted in a tougher material. This design builds on the library of biologically active materials previously explored and aims to bring new biomaterials to the field of 3D-printed personal medicine.

Establishing a point-of-care additive manufacturing workflow for clinical use

Additive manufacturing, or 3-Dimensional (3-D) Printing, is built with technology that utilizes layering techniques to build 3-D structures. Today, its use in medicine includes tissue and organ engineering, creation of prosthetics, the manufacturing of anatomical models for preoperative planning, education with high-fidelity simulations, and the production of surgical guides. Traditionally, these 3-D prints have been manufactured by commercial vendors. However, there are various limitations in the adaptability of these vendors to program-specific needs. Therefore, the implementation of a point-of-care in-house 3-D modeling and printing workflow that allows for customization of 3-D model production is desired. In this manuscript, we detail the process of additive manufacturing within the scope of medicine, focusing on the individual components to create a centralized in-house point-of-care manufacturing workflow. Finally, we highlight a myriad of clinical examples to demonstrate the impact that additive manufacturing brings to the field of medicine.

Accuracy of desktop versus professional 3D printers for maxillofacial model production. A systematic review and meta-analysis

OBJECTIVES

The present review systematically analyzed the accuracy of three-dimensional (3D) maxillofacial skeletal models generated from desktop and professional 3D printers.

DATA/SOURCES

Electronic literature search was conducted in the following databases: PubMed, Embase, Web of Science and Cochrane Library up to September 2020. Two reviewers independently performed the study selection, data extraction and quality assessment of the included studies. Risk of bias was assessed using the Joanna Briggs Critical Appraisal Checklist for Diagnostic Test Accuracy.

STUDY SELECTION/RESULTS

The search strategy retrieved 5680 articles. Following removal of duplicates, title and abstract screening and full-text reading, 20 publications were eligible to be included in the review which focused towards the accuracy of skeletal models generated from either desktop or professional printer. Both types of printers were defined based on their cost, size and layer thickness, where desktop printers cost between $1500-$7000, have a build size of 10×10×10 inches or less and a minimum layer thickness of 100 µm. Whereas, the professional printers cost was between $20,000- $200,000 with a build size of 12×12×12 inches or more and a layer thickness of as less as 3 µm. The risk of bias was found to be low to moderate. Meta-analysis results indicated no significant absolute mean difference (AMD) (p = 0.9487) between desktop (0.12 mm, 95% CI: 0.00-0.27 mm) and professional printers (0.10 mm, 95% CI: 0.04-0.16 mm). Amongst the printing technology, material jetting (0.09 mm, 95% CI: 0.00-0.17 mm) and selective laser sintering (0.09 mm, 95% CI: 0.00-0.26 mm) offered the lowest AMD and the highest difference was observed with the fused deposition modeling (0.22 mm, 95% CI: 0.00-0.53 mm).

CONCLUSIONS

The maxillofacial skeletal models generated from desktop printers offered comparable accuracy to that acquired with professional printers.

CLINICAL SIGNIFICANCE

The desktop 3D printers may be a viable option to print maxillofacial skeletal models for surgical planning, simulation, guide manufacturing and education purposes.

The "Painting by Numbers Method" for education of students in crown preparation

INTRODUCTION

No commercially available solution to improve the teaching of a crown preparation directly on typodont teeth exists at the moment. To fill this gap and support the supervisors of dental courses, a printable and inexpensive tooth was created for structured self-assessment. The aim of this study was to test this printable tooth under realistic pre-clinical situations.

MATERIALS AND METHODS

A two-coloured, double-layer practice tooth was developed. This tooth was consisting of a layer for a correct preparation and the crown. All printed teeth were produced with a stereolithographic printer. 35 voluntary second-year dental students in the second pre-clinical course in prosthodontics were randomly divided into two groups. All students had experience with typodont teeth and models. The first group was trained on four standard model teeth. The second group used model teeth for the first and fourth attempt and printed teeth for second and third attempt. The preparations of the students were scanned by an in-lab scanner and the surface deviations in contrast to a perfect preparation were measured. The differences between the first and fourth attempt were calculated. Benefits of the printed tooth were also evaluated by a questionnaire using German school grades completed by the students (1 = Excellent, 2 = Good, 3 = Satisfactory, 4 = Adequate, 5 = Poor, 6 = Unsatisfactory).

RESULTS

The workflow was feasible and cost-effective regarding the production of the printed teeth. The overall rating of the printed tooth in the questionnaire was good (Ø 2.1 ± 0.22). Students reported different advantages of this method in the free text. The comparison of the preparation between the first and fourth attempt showed that there was a significant better preparation with the printed teeth. The complete preparation had median values of 0.05 mm (Group1: standard model tooth) and -0.03 mm (Group2: printed tooth) (P = .005). Divided into single surfaces, the vestibular and occlusal regions were significantly better. The vestibular surface was 0.11 mm (Group1) and -0.04 mm (Group2) (P = .018). The occlusal surface was 0.13 mm (Group1) and -0.05 mm (Group2) (P = .009).

CONCLUSIONS

The aim of this study was fulfilled. The printed tooth was tested successfully in a pre-clinical course. The feasibility of this teaching concept was confirmed by the questionnaire and the analysis of the preparation form. A significant difference to a standard model tooth was measurable. The students had the possibility to learn a correct crown preparation on a standardised two-layered tooth with included preparation. This printed tooth enabled the students to control the crown preparation directly on their own.

COVID-19 and a Call to Adapt Dental Education

Introduction: COVID-19 has harmed the economic, academic, and clinical pursuits of dental educational institutions and dental students. As dental associations, health agencies, and regulatory bodies around the globe announced the need for social distancing and stricter safety measures, some dental schools worldwide have been adapting to accommodate for such changes.

Methods: This review attempts to provide a general picture of the early responses of some dental schools worldwide to the COVID-19 crisis and identify some of the regulations that influenced dental schools' initial decisions. An analytical approach was used to assess changes to dental school curriculums in didactic (academic/non-clinical) and clinical education, examinations, administration, and dental school research. The assessment was based on a web-based search of a variety of online global references including research articles, reviews, letters, press releases, and surveys regarding the early effect of covid-19 on dental education at some dental institutions in the U.S, Europe, and Asia from late February to early July of 2020. The review also offered further recommendations to dental school administrators regarding the future of dental education during the early stages of a pandemic.

Conclusions: Innovations in technology and blended educational methodologies will continue to influence how certain dental schools around the world adapt to the changes caused by COVID-19 and better prepare dental education institutions for potential future public health disruptions.

Clinical significance: Dental schools will need to adapt their education system to improve didactic, preclinical, clinical, administrative, and research components of dental education in response to the changes caused by COVID-19 and future pandemics.

Visual and haptic perceptibility of 3D printed skeletal models in orthognathic surgery

OBJECTIVE

To assess the anatomical and tactile quality of 3D printed models derived from medical printers for application in orthognathic surgery.

METHODS

A CBCT-scan of an 18 years old female patient was acquired with NewTom VGi evo (NewTom, Verona, Italy). Thereafter, mandibular bone was segmented and isolated from the scan using Mimics inPrint 2.0 software (Materialise NV, Leuven, Belgium). Six printers with different technologies were utilized for printing skeletal models, which included stereolithography (ProX800, 3D Systems, Rock Hill, SC, USA), digital light processing (Perfactory 4 mini XL, Envisiontec, Dearborn, MI, USA), fused deposition modeling (uPrint SE, Stratasys, Eden Prairie, MI, US), colorjet (ProJet CJP 660Pro, 3D Systems, Rock Hill, SC, USA), multijet (Objet Connex 350, Stratasys, Eden Prairie, MN, USA) and selective laser sintering (EOSINT P700, EOS GmbH, Munich, Germany). A questionnaire was designed, where 22 maxillofacial residents scored whether the printed models were able to mimic bone color, texture and anatomy. Five maxillofacial surgeons performed bone cutting with screw insertion/removal to assess the tactile perceptibility.

RESULTS

In relation to texture and cortical and medullary anatomy replication, Perfactory 4 mini XL printer showed the highest mean score, whereas, Objet Connex 350 scored highest for color replication. The haptic feedback for cutting and screw insertion/removal varied for each printer, however, overall it was found to be highest for ProX800, whereas, EOSINT P700 was found to be least favorable.

CONCLUSIONS

The digital light processing based Perfactory 4 mini XL printer offered the most acceptable anatomical model, whereas, deficiencies existed for the replication of haptic feedback to that of real bone with each printer.

CLINICAL SIGNIFICANCE

The study outcomes provide pearls and pitfalls of 3D printed models utilizing various printers and technologies. There is a need for research on multi-material printing as such to improve the haptic feedback of skeletal models and render the models more human bone-like to improve surgical planning and clinical training.

Three-Dimensional Printing of Hydroxyapatite Composites for Biomedical Application

Hydroxyapatite (HA) and HA-based nanocomposites have been recognized as ideal biomaterials in hard tissue engineering because of their compositional similarity to bioapatite. However, the traditional HA-based nanocomposites fabrication techniques still limit the utilization of HA in bone, cartilage, dental, applications, and other fields. In recent years, three-dimensional (3D) printing has been shown to provide a fast, precise, controllable, and scalable fabrication approach for the synthesis of HA-based scaffolds. This review therefore explores available 3D printing technologies for the preparation of porous HA-based nanocomposites. In the present review, different 3D printed HA-based scaffolds composited with natural polymers and/or synthetic polymers are discussed. Furthermore, the desired properties of HA-based composites via 3D printing such as porosity, mechanical properties, biodegradability, and antibacterial properties are extensively explored. Lastly, the applications and the next generation of HA-based nanocomposites for tissue engineering are discussed.

3D and 4D printing in dentistry and maxillofacial surgery: Printing techniques, materials, and applications

3D and 4D printing are cutting-edge technologies for precise and expedited manufacturing of objects ranging from plastic to metal. Recent advances in 3D and 4D printing technologies in dentistry and maxillofacial surgery enable dentists to custom design and print surgical drill guides, temporary and permanent crowns and bridges, orthodontic appliances and orthotics, implants, mouthguards for drug delivery. In the present review, different 3D printing technologies available for use in dentistry are highlighted together with a critique on the materials available for printing. Recent reports of the application of these printed platformed are highlighted to enable readers appreciate the progress in 3D/4D printing in dentistry.

Additive 3-dimensional printing as a novel tool for pre- and postsurgical evaluation and patient education: A clinical case series

BACKGROUND AND OVERVIEW

In contrast to subtractive 3-dimensional (3D) techniques synonymous with computer-aided design and computer-aided manufacturing, rapid progress in additive 3D printing, especially fused filament fabrication or fused deposition modeling, can change the practice of dentistry.

CASE DESCRIPTION

In this article, the authors outline the digital workflow for fused filament fabrication and fused deposition modeling 3D printing that involves converting a Digital Imaging and Communications in Medicine file (scan or radiograph) to a printable Standard Triangle Language file that can be modified (additions or manipulations) using a readily accessible software for 3D printing. The authors also present a clinical case series showing various applications for this technique, including clinician and patient education, treatment planning, and posttreatment evaluations.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The low cost and simple workflow of additive 3D printing has potential to improve precision and efficiency in clinical dentistry for both academic and private practices.

Impact of Layer Thickness and Storage Time on the Properties of 3D-Printed Dental Dies

The purpose of this study was to evaluate the effect of printing layer thickness on the repeatability and surface roughness of 3D-printed dies and detect the effect of layer thickness and storage time on the dimensional stability of 3D-printed dies. One stereolithography (STL) file of an upper molar prepared for a full ceramic crown was used to print three groups of dies: 25 µm, 50 µm, and 100 µm. Repeatability was evaluated by linear and area measurements with a digital caliper and a digital metrology microscope. Dimensional stability was analyzed at 3 weeks, 6 months, and 1 year of storage time. Surface roughness parameters were measured with a 3D confocal laser scanning microscope. Statistics were completed using one-way analysis of variance and Tukey’s post hoc tests, p < 0.05. Printing time decreased as layer thickness increased. All groups showed high repeatability and comparable surface roughness while showing differences in their linear dimensions and surface areas. At the 3 week storage interval, dimensional changes were observed in all groups. Within this experimental study’s constraints, it can be concluded that changing the 3D-printing layer thickness does not affect the repeatability or the surface roughness of the product; meanwhile, changes to the layer thickness and storage time influence the dimensional stability of 3D-printed dies.

A Review of 3D Printing in Dentistry: Technologies, Affecting Factors, and Applications

Three-dimensional (3D) printing technologies are advanced manufacturing technologies based on computer-aided design digital models to create personalized 3D objects automatically. They have been widely used in the industry, design, engineering, and manufacturing fields for nearly 30 years. Three-dimensional printing has many advantages in process engineering, with applications in dentistry ranging from the field of prosthodontics, oral and maxillofacial surgery, and oral implantology to orthodontics, endodontics, and periodontology. This review provides a practical and scientific overview of 3D printing technologies. First, it introduces current 3D printing technologies, including powder bed fusion, photopolymerization molding, and fused deposition modeling. Additionally, it introduces various factors affecting 3D printing metrics, such as mechanical properties and accuracy. The final section presents a summary of the clinical applications of 3D printing in dentistry, including manufacturing working models and main applications in the fields of prosthodontics, oral and maxillofacial surgery, and oral implantology. The 3D printing technologies have the advantages of high material utilization and the ability to manufacture a single complex geometry; nevertheless, they have the disadvantages of high cost and time-consuming postprocessing. The development of new materials and technologies will be the future trend of 3D printing in dentistry, and there is no denying that 3D printing will have a bright future.

4D Printing: Materials, Technologies, and Future Applications in the Biomedical Field

4D printing can be defined as the fabrication of structures using smart materials that allow the final object to change its shape, properties, or function in response to an external stimulus such as light, heat, or moisture. The available technologies, materials, and applications have evolved significantly since their first development in 2013, with prospective applications within the aerospace, manufacturing, and soft robotic industries. This review focuses on the printing technologies and smart materials currently available for fabricating these structures. The applications of 4D printing within biomedicine are explored with a focus on tissue engineering, drug delivery, and artificial organs. Finally, some ideas for potential uses are proposed. 4D printing is making its mark with seemingly unlimited potential applications, however, its use in mainstream medical treatments relies on further developments and extensive research investments.

Use of 3D printing in the planning of a patient with unerupted maxillary central incisors

Impacted central incisors are a clinical dilemma faced by orthodontists, oral and maxillofacial surgeons, paediatric and restorative dentists. Successful management requires a robust diagnosis and treatment planning process. This case report highlights the use of 3D printing to aid the treatment planning of a patient with bilateral unerupted maxillary central incisors due to two supernumerary teeth acting as a physical obstruction. The preoperative cone beam computed tomography scan allowed for production of the printed model to the exact size and dimensions of the unerupted teeth and supernumeraries to facilitate the planning of the case and to aid in consenting the patient for treatment.

Rapid additive manufacturing of an obturator prosthesis with the use of an intraoral scanner: A dental technique

A protocol for a completely digital manufacturing process for an obturator prosthesis is described. An intraoral scanner was used to capture the mandible and maxilla together with the sinus defect. The obturator base and the artificial teeth were created with a computer-aided design software program and manufactured by 3-dimensional printing. Stainless steel clasps provided the retention for the prosthesis.

In Vitro Comparison of Surgical Implant Placement Accuracy Using Guides Fabricated by Three Different Additive Technologies

Various three-dimensional (3D) printing technologies are commercially available on the market, but the influence of different technologies on the accuracy of implant-guided surgery is unclear. Thus, three printing technologies: Stereolithographic (SLA), Digital light processing (DLP), and Polyjet were evaluated in this study. An entire 30 polyurethane models replicated the clinical situation. Ten surgical guides were printed by SLA, DLP, and PolyJet. Then, implant-guided surgery was performed, and their accuracy outcomes were measured concerning angular deviation, 3D deviation at the entry point, and apex. On top of that, the total processing time was also compared. For the angular deviation, the mean deviation was not statistically significant among all technologies. For the 3D deviation, PolyJet was statistically more accurate than DLP (p = 0.002) and SLA (p = 0.017) at the entry point. PolyJet was also statistically more accurate than DLP (p = 0.007) in regards to 3D deviation at the apex. Within the limitation of this study, the deviations from the experiment showed that PolyJet had the best outcome regarding the 3D deviations at the entry point and at the apex, meanwhile, the DLP printer had the shortest processing time.

Validation of a three-dimensional printed model for training of surgical extraction of supernumerary teeth

INTRODUCTION

This study aimed to validate a three-dimensional (3D) printed model to provide training for supernumerary teeth (SNTs) extraction.

MATERIALS AND METHODS

Each of the 30 participants, grouped as experienced and without experience, conducted two identically simulated surgeries on a 3D-printed replica of human mixed dentition with a SNT. The surgery time, area of bony window and volume of removed material were measured; subsequently, responses to a five-item questionnaire were recorded. The collected data were statistically analysed.

RESULTS

The surgery time was 228.37 ± 141.53 seconds and 125.47 ± 53.03 seconds in the first and second surgery, respectively. The training significantly decreased the surgery time in the participants without experience (P = .000). However, there were no significant differences in the area of window opening (P = .271) and volume of removed material between the two surgeries (P = .075). The participants who perceived educational benefits accounted for more than 60% of the respondents for every question. Participants without experience in SNT extraction showed a tendency to rate a higher score than did those with experience.

CONCLUSIONS

A 3D-printed model for surgical extraction of a SNT can improve surgical skill and, especially, shorten the learning curve in beginners.

Comparison of 3D-Printed Dental Implants with Threaded Implants for Osseointegration: An Experimental Pilot Study

This study aimed to compare bone healing and implant stability for three types of dental implants: a threaded implant, a three-dimensional (3D)-printed implant without spikes, and a 3D-printed implant with spikes. In four beagle dogs, left and right mandibular premolars (2nd, 3rd, and 4th) and 1st molars were removed. Twelve weeks later, three types of titanium implants (threaded implant, 3D-printed implant without spikes, and 3D-printed implant with spikes) were randomly inserted into the edentulous ridges of each dog. Implant stability measurements and radiographic recordings were taken every two weeks following implant placement. Twelve weeks after implant surgery, the dogs were sacrificed and bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) were compared between groups. At implant surgery, the primary stability was lower for the 3D-printed implant with spikes (74.05 ± 5.61) than for the threaded implant (83.71 ± 2.90) (p = 0.005). Afterwards, no significant difference in implants' stability was observed between groups up to post-surgery week 12. Histomorphometrical analysis did not reveal a significant difference between the three implants for BIC (p = 0.101) or BAFO (p = 0.288). Within the limits of this study, 3D-printed implants without spikes and threaded implants showed comparable implant stability measurements, BIC, and BAFO.

Accuracy of 3-Dimensionally Printed Full-Arch Dental Models: A Systematic Review

The use of additive manufacturing in dentistry has exponentially increased with dental model construction being the most common use of the technology. Henceforth, identifying the accuracy of additively manufactured dental models is critical. The objective of this study was to systematically review the literature and evaluate the accuracy of full-arch dental models manufactured using different 3D printing technologies. Seven databases were searched, and 2209 articles initially identified of which twenty-eight studies fulfilling the inclusion criteria were analysed. A meta-analysis was not possible due to unclear reporting and heterogeneity of studies. Stereolithography (SLA) was the most investigated technology, followed by digital light processing (DLP). Accuracy of 3D printed models varied widely between <100 to >500 μm with the majority of models deemed of clinically acceptable accuracy. The smallest (3.3 μm) and largest (579 μm) mean errors were produced by SLA printers. For DLP, majority of investigated printers (n = 6/8) produced models with <100 μm accuracy. Manufacturing parameters, including layer thickness, base design, postprocessing and storage, significantly influenced the model’s accuracy. Majority of studies supported the use of 3D printed dental models. Nonetheless, models deemed clinically acceptable for orthodontic purposes may not necessarily be acceptable for the prosthodontic workflow or applications requiring high accuracy.

Tribological performance of the pair human teeth vs 3D printed zirconia: An in vitro chewing simulation study

This study aims to evaluate the tribological performance of the pair human teeth/robocasted zirconia, with a special focus on the enamel wear mechanisms. Zirconia pieces produced by robocasting (RC) and unidirectional compression (UC) were compared in terms of crystalline structure, density, porosity, hardness and toughness. Chewing simulation tests were performed against human dental cusps. The cusps wear was quantified and the wear mechanisms identified. Although most of the properties of UC and RC samples are similar, differences were observed for surface roughness and porosity. Although the samples did not suffer wear, the antagonist cusps worn in a similar way. In conclusion, robocasting seems a promising technique to produce customized zirconia dental pieces, namely in what concerns the overall tribological behaviour.

3D printing in pharmaceuticals: An emerging technology full of challenges

Although in its infancy, when compared with the other sectors, year 2005 marked the rapid evolution of 3 Dimensional printing (3DP) technologies in pharma sector with a huge potential in the dosage form designing and personalisation of the medication. 3DP is an innovative and highly promising way for the instant manufacturing in contrast with the tailored made conventional manufacturing. Various 3DP technologies are categorized into the various areas on the basis of the type of material used, deposition techniques and the solidification/fusion techniques. 3DP technologies have multiple pharmaceutical applications including formulation of the precise and unique dosage forms, medical research, personalization of medicine, tissues engineering and surgical application. In the present article, we have accentuated the comparative merits and demerits of various 3DP technologies used in the pharmaceutical sector. An insight in to the challenges, apropos availability and the choice of the excipients, as well as the printer, regulatory and safety concern of the product is provided.

3D Printing Technologies: Recent Development and Emerging Applications in Various Drug Delivery Systems

The 3D printing is considered as an emerging digitized technology that could act as a key driving factor for the future advancement and precise manufacturing of personalized dosage forms, regenerative medicine, prosthesis and implantable medical devices. Tailoring the size, shape and drug release profile from various drug delivery systems can be beneficial for special populations such as paediatrics, pregnant women and geriatrics with unique or changing medical needs. This review summarizes various types of 3D printing technologies with advantages and limitations particularly in the area of pharmaceutical research. The applications of 3D printing in tablets, films, liquids, gastroretentive, colon, transdermal and intrauterine drug delivery systems as well as medical devices have been briefed. Due to the novelty and distinct features, 3D printing has the inherent capacity to solve many formulation and drug delivery challenges, which are frequently associated with poorly aqueous soluble drugs. Recent approval of Spritam® and publication of USFDA technical guidance on additive manufacturing related to medical devices has led to an extensive research in various field of drug delivery systems and bioengineering. The 3D printing technology could be successfully implemented from pre-clinical phase to first-in-human trials as well as on-site production of customized formulation at the point of care having excellent dose flexibility. Advent of innovative 3D printing machineries with built-in flexibility and quality with the introduction of new regulatory guidelines would rapidly integrate and revolutionize conventional pharmaceutical manufacturing sector.

A novel method for fabricating nasoalveolar molding appliances for infants with cleft lip and palate using 3-dimensional workflow and clear aligners

INTRODUCTION

Nasoalveolar molding (NAM) was introduced over 20 years ago as adjunctive therapy for the correction of cleft lip and palate. In the current study, we propose a new approach using a digital workflow and 3-dimensional printing to fabricate clear aligner NAM devices.

METHODS

A polyvinyl siloxane (PVS) impression of an infant with a unilateral complete cleft lip and palate (UCLP) is acquired and poured, and the stone model is scanned with an intraoral scanner. The stereolithography file is digitized, and the alveolar segments are digitally segmented and moved to the desired final position. The total distance moved is divided into a sequence of 1-1.5 mm increments, creating a series of digital models. The models are 3-dimensionally printed along with button templates to allow free form positioning of the button on each model. A Vacuform machine (Taglus, Mumbai, India) was used to fabricate a 0.040-in aligner for each stage.

RESULTS

We present 1 case that was treated successfully with this approach. Appointments for the NAM adjustments were primarily to monitor progress and counseling with less time spent adjusting the appliance. The appointment length was reduced by over 30 minutes. Benefits of the aligner are improved fit, more precise increments of activation, reduced chairside time, and potentially minimized number of visits.

CONCLUSIONS

NAM custom aligners may provide similar benefits to the traditional approach while reducing the burden of care by reducing the number of visits and appointment duration. Further studies with a sample and longitudinal observations are needed to investigate the benefits of the proposed digital approach.

Comparison of the accuracy of implants placed with CAD-CAM surgical templates manufactured with various 3D printers: An in vitro study

STATEMENT OF PROBLEM

The fit of a 3D printed surgical template will directly influence the accuracy of guided implant surgery. Various 3D printing technologies are currently available with different levels of resolution and printing accuracy; however, how the different systems affect accuracy is unclear.

PURPOSE

The purpose of this in vitro study was to assess the effect of using various 3D printers for the fabrication of implant surgical templates and its effect on the definitive implant position compared with the planned implant position.

MATERIAL AND METHODS

A cone beam computed tomography scan from a partially edentulous patient and an extraoral digital scan of a dental cast obtained from the same patient were used. The digital imaging and communications in medicine and standard tessellation language (STL) files were imported to an implant planning software program and merged, and an implant was digitally positioned in the mandibular right first molar region. A surgical template was designed and exported as an STL file. Ten surgical templates were printed for each of the following groups: stereolithography (SLA) printing, PolyJet, and MultiJet. The region where the implant was planned was cut away from the cast onto which the surgical templates were seated, allowing a passive positioning of the implant through the template, which was held in place with polyvinyl siloxane material. A scan body was inserted in the implant, and the cast was scanned with a laboratory scanner. The STL files obtained from the definitive implant position were imported into an implant planning software program and registered with the planned implant position, allowing for a comparison between the planned and actual implant position. Mean deviations were measured for angle deviation, entry point offset, and apex offset. Data normality was tested by using the Shapiro-Wilk test. The Kruskal-Wallis test was used to determine whether the outcomes of angle deviation, apex offset, and entry offset were statistically different between groups (α=.05).

RESULTS

The median and interquartile range for the angle deviation (degrees) were 1.30 (0.62) for SLA; 1.15 (1.23) for Polyjet; and 1.10 (0.65) for Multijet. No statistically significant differences were found in the angular deviation among groups (χ2(2)=3.08, P=.21). The median and interquartile range for the entry offset and apex offset (mm) were 0.19 (0.16) and 0.36 (0.16) for SLA, respectively; 0.20 (0.13) and 0.34 (0.26) for Polyjet, respectively; and 0.23 (0.10) and 0.32 (0.08) for Multijet, respectively. Similarly, nonsignificant differences were found for entry point offset (χ2(2)=0.13, P=.94) and apex offset (χ2(2)=1.08, P=.58).

CONCLUSIONS

The different types of 3D printing technology used in this study did not appear to have a significant effect on the accuracy of guided implant surgery.

3D-printed Surgical Training Model Based on Real Patient Situations for Dental Education

Background: Most simulation models used at university dental clinics are typodonts. Usually, models show idealized eugnathic situations, which are rarely encountered in everyday practice. The aim of this study was to use 3D printing technology to manufacture individualized surgical training models for root tip resection (apicoectomy) on the basis of real patient data and to compare their suitability for dental education against a commercial typodont model. Methods: The training model was designed using CAD/CAM (computer-aided design/computer-aided manufacturing) technology. The printer used to manufacture the models employed the PolyJet technique. Dental students, about one year before their final examinations, acted as test persons and evaluated the simulation models on a visual analogue scale (VAS) with four questions (Q1-Q4). Results: A training model for root tip resection was constructed and printed employing two different materials (hard and soft) to differentiate anatomical structures within the model. The exercise was rated by 35 participants for the typodont model and 33 students for the 3D-printed model. Wilcoxon rank sum tests were carried out to identify differences in the assessments of the two model types. The alternative hypothesis for each test was: "The rating for the typodont model is higher than that for the 3D-printed model". As the p-values reveal, the alternative hypothesis has to be rejected in all cases. For both models, the gingiva mask was criticized. Conclusions: Individual 3D-printed surgical training models based on real patient data offer a realistic alternative to industrially manufactured typodont models. However, there is still room for improvement with respect to the gingiva mask for learning surgical incision and flap formation.

Artificial intelligence in fixed implant prosthodontics: a retrospective study of 106 implant-supported monolithic zirconia crowns inserted in the posterior jaws of 90 patients

Background

Artificial intelligence (AI) is a branch of computer science concerned with building smart software or machines capable of performing tasks that typically require human intelligence. We present a protocol for the use of AI to fabricate implant-supported monolithic zirconia crowns (MZCs) cemented on customized hybrid abutments.

Methods

The study protocol consisted of: (1) intraoral scan of the implant position; (2) design of the individual abutment and temporary crown using computer-aided design (CAD) software; (3) milling of the zirconia abutment and the temporary polymethyl-methacrylate (PMMA) crown, with extraoral cementation of the zirconia abutment on the relative titanium bonding base, to generate an individual hybrid abutment; (4) clinical application of the hybrid abutment and the temporary PMMA crown; (5) intraoral scan of the hybrid abutment; (6) CAD of the final crown with automated margin line design using AI; (7) milling, sintering and characterisation of the final MZC; and (8) clinical application of the MZC. The outcome variables were mathematical (quality of the fabrication of the individual zirconia abutment) and clinical, such as (1) quality of the marginal adaptation, (2) of interproximal contact points and (3) of occlusal contacts, (4) chromatic integration, (5) survival and (6) success of MZCs. A careful statistical analysis was performed.

Results

90 patients (35 males, 55 females; mean age 53.3 ± 13.7 years) restored with 106 implant-supported MZCs were included in the study. The follow-up varied from 6 months to 3 years. The quality of the fabrication of individual hybrid abutments revealed a mean deviation of 44 μm (± 6.3) between the original CAD design of the zirconia abutment, and the mesh of the zirconia abutment captured intraorally at the end of the provisionalization. At the delivery of the MZCs, the marginal adaptation, quality of interproximal and occlusal contacts, and aesthetic integration were excellent. The three-year cumulative survival and success of the MZCs were 99.0% and 91.3%, respectively.

Conclusions

AI seems to represent a reliable tool for the restoration of single implants with MZCs cemented on customised hybrid abutments via a full digital workflow. Further studies are needed to confirm these positive results.

Feasibility of a 3D Surgical Guide Technique for Impacted Supernumerary Tooth Extraction: A Pilot Study with 3D Printed Simulation Models

This study aimed to evaluate the feasibility of a 3-dimensional (3D) planned surgical guide technique designed for impacted supernumerary teeth (STs) extraction using 3D printed simulation models. In total, 17 participants from two university hospitals were recruited. Each participant performed surgery with both the conventional and surgical guide techniques. The following parameters were evaluated: (1) The time required for ST extraction, (2) the area of the window opening, and (3) the volume of the material removed. Time required for ST extraction was 213.65 ± 167.45 sec and 114.76 ± 42.87 sec in the conventional and surgical guide techniques, respectively, with significant differences (p = 0.028). The required area of the window opening was 48.10 ± 9.44 mm2 and 45.90 ± 8.17 mm2, respectively, in the conventional and surgical guide techniques, with no significant differences (p > 0.05). The required volume of the material removed was 121.65 ± 43.69 mm3 and 99.12 ± 17.88 mm3 in the conventional and surgical guide techniques, respectively, with significant differences (p = 0.031). The 3D planned surgical guide technique was effective for impacted ST extraction. Within the limits of this study, the surgical guide technique allows us to accomplish minimally invasive surgery within a shorter duration.

Shaping the future: recent advances of 3D printing in drug delivery and healthcare

Introduction: Three-dimensional (3D) printing is a relatively new, rapid manufacturing technology that has found promising applications in the drug delivery and medical sectors. Arguably, never before has the healthcare industry experienced such a transformative technology. This review aims to discuss the state of the art of 3D printing technology in healthcare and drug delivery. Areas covered: The current and future applications of printing technologies within drug delivery and medicine have been discussed. The latest innovations in 3D printing of customized medical devices, drug-eluting implants, and printlets (3D-printed tablets) with a tailored dose, shape, size, and release characteristics have been covered. The review also covers the state of the art of 3D printing in healthcare (covering topics such as dentistry, surgical and bioprinting of patient-specific organs), as well as the potential of recent innovations, such as 4D printing, to shape the future of drug delivery and to improve treatment pathways for patients. Expert opinion: A future perspective is provided on the potential for 3D printing in healthcare, covering strategies to overcome the major barriers to integration that are faced today.

The Applications of 3D Printing for Craniofacial Tissue Engineering

Three-dimensional (3D) printing is an emerging technology in the field of dentistry. It uses a layer-by-layer manufacturing technique to create scaffolds that can be used for dental tissue engineering applications. While several 3D printing methodologies exist, such as selective laser sintering or fused deposition modeling, this paper will review the applications of 3D printing for craniofacial tissue engineering; in particular for the periodontal complex, dental pulp, alveolar bone, and cartilage. For the periodontal complex, a 3D printed scaffold was attempted to treat a periodontal defect; for dental pulp, hydrogels were created that can support an odontoblastic cell line; for bone and cartilage, a polycaprolactone scaffold with microspheres induced the formation of multiphase fibrocartilaginous tissues. While the current research highlights the development and potential of 3D printing, more research is required to fully understand this technology and for its incorporation into the dental field.

Current Biomedical Applications of 3D Printing and Additive Manufacturing

Additive manufacturing (AM) has emerged over the past four decades as a cost-effective, on-demand modality for fabrication of geometrically complex objects. The ability to design and print virtually any object shape using a diverse array of materials, such as metals, polymers, ceramics and bioinks, has allowed for the adoption of this technology for biomedical applications in both research and clinical settings. Current advancements in tissue engineering and regeneration, therapeutic delivery, medical device fabrication and operative management planning ensure that AM will continue to play an increasingly important role in the future of healthcare. In this review, we outline current biomedical applications of common AM techniques and materials.