3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

3D printing in dentistry.

Intraoral scanners (IOS) are devices for capturing direct optical impressions in dentistry. The purpose of this narrative review on the use of IOS was to: (1) identify the advantages/disadvantages of using optical impressions compared to conventional impressions; (2) investigate if optical impressions are as accurate as conventional impressions; (3) evaluate the differences between the IOS currently available commercially; (4) determine the current clinical applications/limitations in the use of IOS. Electronic database searches were performed using specific keywords and MeSH terms. The searches were confined to full-text articles written in English and published in peer-reviewed journals between January 2007 and June 2017. One hundred thirty-two studies were included in the present review; among them, 20 were previous literature reviews, 78 were in vivo clinical studies (6 randomized controlled/crossover trials, 31 controlled/comparative studies; 24 cohort studies/case series; 17 case reports) and 34 were in vitro comparative studies. Optical impressions reduce patient discomfort; IOS are time-efficient and simplify clinical procedures for the dentist, eliminating plaster models and allowing better communication with the dental technician and with patients; however, with IOS, it can be difficult to detect deep margin lines in prepared teeth and/or in case of bleeding, there is a learning curve, and there are purchasing and managing costs. The current IOS are sufficiently accurate for capturing impressions for fabricating a whole series of prosthetic restorations (inlays/onlays, copings and frameworks, single crowns and fixed partial dentures) on both natural teeth and implants; in addition, they can be used for smile design, and to fabricate posts and cores, removable partial prostheses and obturators. The literature to date does not support the use of IOS in long-span restorations with natural teeth or implants. Finally, IOS can be integrated in implant dentistry for guided surgery and in orthodontics for fabricating aligners and custom-made devices.

/pdf/intraoral-scanners-in-dentistry-a-review-of-the-current-26q4ueb6fl.pdf

Intraoral scanners in dentistry: a review of the current literature

https://www.journalofprosthodonticresearch.com/article/S1883-1958(16)00009-8/pdf

Advancements in CAD/CAM technology: Options for practical implementation

Classroom assessment techniques : a handbook for collegeteachers / Thomas A. Angelo, K. Patricia Cross

Purpose To conduct a systematic review to evaluate the evidence of possible benefits and accuracy of digital impression techniques vs. conventional impression techniques. Materials and methods Reports of digital impression techniques versus conventional impression techniques were systematically searched for in the following databases: Cochrane Central Register of Controlled Trials, PubMed, and Web of Science. A combination of controlled vocabulary, free-text words, and well-defined inclusion and exclusion criteria guided the search. Results Digital impression accuracy is at the same level as conventional impression methods in fabrication of crowns and short fixed dental prostheses (FDPs). For fabrication of implant-supported crowns and FDPs, digital impression accuracy is clinically acceptable. In full-arch impressions, conventional impression methods resulted in better accuracy compared to digital impressions. Conclusions Digital impression techniques are a clinically acceptable alternative to conventional impression methods in fabrication of crowns and short FDPs. For fabrication of implant-supported crowns and FDPs, digital impression systems also result in clinically acceptable fit. Digital impression techniques are faster and can shorten the operation time. Based on this study, the conventional impression technique is still recommended for full-arch impressions.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/jopr.12527

Digital Versus Conventional Impressions in Fixed Prosthodontics: A Review

Active learning is an instructional method in which students become engaged participants in the classroom through the use of in-class written exercises, games, problem sets, audience-response syste...

https://www.physiology.org/doi/pdf/10.1152/advan.00014.2014

A Comparison of Professional-Level Faculty and Student Perceptions of Active Learning: Its Current Use, Effectiveness, and Barriers.

In engaging lectures, also referred to as broken or interactive lectures, students are given short periods of lecture followed by “breaks” that can consist of 1-min papers, problem sets, brainstorm...

A comparison of traditional and engaging lecture methods in a large, professional-level course

Statement of problem Conventional impression materials and techniques have been used successfully to fabricate fixed restorations. Recently, digital pathways have been developed, but insufficient data are available regarding their marginal accuracy. Purpose The purpose of this in vitro study was to compare the marginal gap discrepancy of lithium disilicate single crowns fabricated with computer-aided design and computer-aided manufacturing (CAD/CAM) technology by using both conventional and 2 digital impression techniques. Material and methods One typodont maxillary right central incisor was prepared for a ceramic crown. Ten impressions were made by using each method: conventional with polyvinyl siloxane impression material, Lava COS (3M ESPE), and iTero (Cadent) intraoral scanning devices. Lithium disilicate (e.max CAD) crowns were fabricated with CAD/CAM technology, and the marginal gap was measured for each specimen at 4 points under magnification with a stereomicroscope. The mean measurement for each location and overall mean gap size by group were calculated. Statistically significant differences among the impression techniques were tested with F and t tests (α=.05). Results The average (±SD) gap for the conventional impression group was 112.3 (±35.3) μm. The digital impression groups had similar average gap sizes; the Lava group was 89.8 (±25.4) μm, and the iTero group was 89.6 (±30.1) μm. No statistically significant difference was found in the effects among impression techniques ( P =.185) Conclusions Within the limitations of this study, digital and conventional impressions were found to produce crowns with similar marginal accuracy.

/pdf/comparison-of-the-marginal-fit-of-lithium-disilicate-crowns-4lq836thez.pdf

Comparison of the marginal fit of lithium disilicate crowns fabricated with CAD/CAM technology by using conventional impressions and two intraoral digital scanners.

Introduction

With increasing use of digital scanning with restorative procedures in the dental office, it becomes necessary that educational institutions adopt instructional methodology for introducing this technology together with conventional impression techniques.



Objective

To compare the time differences between instructing dental students on digital scanning (DS) (LAVA C.O.S. digital impression system) and a conventional impression technique (CI) (polyvinyl siloxane), and to compare students’ attitudes and beliefs towards both techniques.



Materials and methods

Volunteer sophomore dental students (n = 25) with no prior experience in clinical impressions were recruited and IRB consent obtained. Participants responded to a pre-and post-exposure questionnaire. Participants were instructed on the use of both DS and CI for a single tooth full coverage crown restoration using a consecutive sequence of video lecture, investigator-led demonstration and independent impression exercise. The time necessary for each step (minutes) was recorded. Statistical significance was calculated using dependent t-tests (time measurements) and 2-sample Mann–Whitney (questionnaire responses).



Results

The time spent teaching students was greater for DS than CI for video lecture (15.95 and 10.07 min, P = 0.0000), demonstration time (9.06 and 4.70 min, P = 0.0000) and impression time (18.17 and 8.59 min, P = 0.0000). Prior to the instruction and practice, students considered themselves more familiar with CI (3.96) than DS (1.96) (P = 0.0000). After the instruction and practice, participants reported CI technique proved significantly easier than expected (pre-instruction: 3.52 and post-instruction: 4.08, P = 0.002). However, overall participants’ perception of ease of use for DS was not influenced by this instruction and practice experience (pre-instruction: 3.84 and post-instruction: 3.56, P = 0.106). Despite the results, 96% of participants expressed an expectation that DS will become their predominant impression technique during their careers.



Conclusions

Dental students with no clinical experience have high expectations for digital scanning, and despite their initial difficulty, expect it to become their primary impression technique during their professional futures. The instructional time necessary for introducing DS into the curriculum is significantly greater than CI in both classroom (lecture) and clinical simulation settings (investigator-led demonstration).

/pdf/comparison-of-digital-scanning-and-polyvinyl-siloxane-4s9qyb5583.pdf

Comparison of digital scanning and polyvinyl siloxane impression techniques by dental students: instructional efficiency and attitudes towards technology.

The purpose of this case report was to present the use of a contemporary digital photograph-assisted virtual smile design principle, an intraoral digital impression, and computer-aided design/computer-aided manufacture-fabricated lithium disilicate ceramic veneers to treat a patient with esthetic needs in the maxillary anterior region. By using the proposed digital restorative work flow, this case report demonstrated an effective communication pathway between the patient, clinician, and dental laboratory technician. Effective communication can help to achieve a more predictable and satisfactory esthetic outcome.

Predictable Restorative Work Flow for Computer-Aided Design/Computer-Aided Manufacture-Fabricated Ceramic Veneers Utilizing a Virtual Smile Design Principle

Michael J. Metz

Papers

A Comparison of Professional-Level Faculty and Student Perceptions of Active Learning: Its Current Use, Effectiveness, and Barriers.

A comparison of traditional and engaging lecture methods in a large, professional-level course

Comparison of the marginal fit of lithium disilicate crowns fabricated with CAD/CAM technology by using conventional impressions and two intraoral digital scanners.

Comparison of digital scanning and polyvinyl siloxane impression techniques by dental students: instructional efficiency and attitudes towards technology.

Predictable Restorative Work Flow for Computer-Aided Design/Computer-Aided Manufacture-Fabricated Ceramic Veneers Utilizing a Virtual Smile Design Principle