Costa Rica: Researchers Design 3D Printed Medical Device for Suturing Extremities

Our skin protects us from invading microorganisms and foreign substances, eliminates harmful toxins, helps to regulate our core body temperature, and is in charge of receiving both tactile and thermal stimulation. But, it’s fragile and easily damaged, which can lead to open wounds that get infected. Michelle Orozco-Brenes, José A. Jiménez-Chavarría, and Dagoberto Arias-Aguilar, researchers out of Costa Rica, published a paper, titled “Design of a medical device for superficial suturing upper and lower extremities,” about their work creating a medical suturing device.

“This work presents the design for a class 2 medical device that meets the basic requirements of the current and known suturing methods in Costa Rica,” the abstract states. “The design process was achieved in three main stages, (i)Research on similar technologies; e.g. The operation principles of a sewing machine, materials used; (ii) The study of types of skin traumas; (iii) General approach toward the suturing device, including device functionality, integration with the human body and manufacturing process. The device model was designed and fabricated using 3D printing technology, this allowed the team to analyze ergonomics, the assembly of the parts and the equipment’s motion. The printed prototype made it possible for potential users to provide feedback on the design and suggestions for improvement.”

Figure 1. SolidWorks design of the medical device to be printed.

Suturing means to connect blood vessels with a specific material, such as thread, when tissue is torn in a way that halts natural healing. You can find many suturing devices on the market around the world, but Costa Rican hospitals don’t typically use them, as they are complex and costly. So the team set out to design a class 2 FDA electronic medical device that could both reduce tissue damage and uniformly, and quickly, suture a wound so an “aesthetically acceptable” scar is left behind.

“The idea for a medical device to suture arose for three main reasons,” the researchers wrote. “First, physicians were noticing poorly sutured wounds that would result in large scars. These in some cases required further procedures like plastic surgery. Also, time consumption, making the search for a device that would make the method faster a necessity. Finally, sutures stitched by hand are sometimes left too loose or too tight, causing bleeding from the wound.”

Table 2. Schematic representation of the function of the suturing medical device.

Device specifications were functionality, cost, durability, modularity, and reliability. They used SOLIDWORKS software to create the design for their model, which required three specific functions:

  • Stabilize the skin
  • Rotate the needle on its axis to join tissue sections
  • Initiate and finish with the least possible amount of user interference

“The final design was oriented to have the area and volume of the shell as similar as possible for the needle to rotate 360° without any problem,” the researchers explained.

In order to test out several functionality features, they 3D printed a prototype first, using Polyjet technology to fabricate the piston and and an FDM printer for most of the other parts. Due to its high strength and toughness, corrosion and fatigue resistance, and low friction coefficient, they used the AISI 316L alloy for the prototype.

The suturing device has seven main components. The shell encases the device, while two guides allow the movement of the guide pin, which is used to tie a double knot. Rollers provide the rotational movement that allows for the suturing, while a piston gives the rollers their movement. The final parts are a ½ circle needle with tapered tip, and nylon thread, which has good elasticity for skin retention and closure.

Figure 2. Final design for the suturing medical device.

To use the device, the needle is first threaded in its initial position at the top of the shell, and then set in the rollers. The piston lowers the shell, and the needle is rotated 270° to pinch the tissue for suturing. The knot is initiated when the rollers, guided by the holder, turn 45° to the right, and the pin is set in place over the guide. The needle makes a 360° turn on its axis, and the guides turn over the shell and let go of the guide pin, “letting it fall due to gravity over the guides” beneath it to finish the first knot. The first few steps are repeated, and after the final full turn, the user tenses the thread through the top hole, until it’s kept that way through the guide pin. The lower guides will release, and the guide pin is removed, completing the double knot.

“After the prototype was assembled and design functions checked, the final step required a survey,” the team wrote. “The study contained questions about the medical device presented via prototype and they were asked to elaborate on their answers regarding their opinion as health professionals.”

Table 3. Survey on trained medical physicians.

The 3D printed prototype device was presented to Dr. Stephanie Gómez Najéra, Dr. Pamela Villareal Valverde, and Dr. Tatiana Piedra Chacón. The numbers listed in the survey results are the average between these three Costa Rican physicians, and the scale, based on the Likert scale, goes from 1-5, with 1 being strongly disagree and 5 being strongly agree.

“The comments reference that the usefulness depends on the context of where it would be applied, for example a jail or emergency room,” the researchers wrote of the doctors’ opinions on their device.

“One main drawback is that the device may not be suitable for all types of wounds. Other concerns raised by the physicians were related to the price and size of the device.”

Based on observations from the survey, the researchers modified the final prototype to “improve its ergonomic factor” by adding a holder at the top of the shell for more stability and easier manipulation.

Next steps include standardizing parts of the prototype so that some pieces can be purchased in the market, and optimizing the mechanisms, like the servomotor, sensors, and motors, that generate the device’s movements.

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Formlabs Tells Us How to Make Good Looking 3D Printed Dentures

More than 36 million Americans do not have any teeth, and 120 million people in the US are missing at least one tooth. With these numbers expected to grow in the next two decades, the market for 3D printed dentures is expected to grow significantly.

Sam Wainwright, Dental Product Manager at Formlabs, suggested during the company’s latest webinar that he wouldn’t “be surprised to see 40% of dentures in America made with 3D printing,” claiming that it makes sense “at the technology level because there is no loss of material.” The expert delved into some of the techniques that have proven to work for aesthetically better 3D printed dentures. The webinar, titled Can 3D printed dentures look good?, offered dentists, technicians, and anyone interested in using 3D printing to improve dentures, tips on how to cut material costs by up to 80% (compared to traditional denture cards and acrylic); perform fewer steps to attain high-quality results, and overall prevent teeth from looking unnatural. 

“This is an ever expanding market with many options. 3D printed dentures are a very new thing, especially for removable prosthetics (something that has never been digitalized) so it is going to take some time for labs, dentists and patients to become used to it. The material is indicated for long term use but the most rapid adoption of this technology will be immediate conversion and provisional dentures, which have lower risk allowing dental professionals to walk not run into this new technology. We also expect the resins to get better, stronger and more aesthetic in time,” said Wainwright.

In fact, in the last year, Formlabs has already managed to upgrade the resins it sells for medical professionals to make oral prostheses, called Digital Dentures. These new FDA-approved resins not only resemble traditional dentures but they are also cheaper than other options. At $299 for the denture base resin and $399 for the teeth resin, the company estimates that the total resin cost for a maxillary denture is $7.20. Moreover, Formlabs also recently released the new Form 3 printer, which uses light touch supports: meaning post-processing just became much easier. Support removal is going to be quicker on the Form 3 than the Form 2, which translates to fewer materials costs and time.

“We are trying to prevent teeth from looking unnatural, and sometimes with these 3D printed dentures, the aesthetics are really suffering from it. We like to think that dentures should have life-like gingiva, natural cervical margins, individual looking-teeth, and be easy to assemble,” Wainright said.

The general basic workflow proposed by Wainright is to follow the traditional workflow until the final models are poured and articulated with wax rim, that set-up needs to be made digital with a desktop dental 3D scanner allowing for the digital design in any open CAD dental system, followed by 3D printing the base and teeth, and finally post-processing, assembling and finishing the piece. 

“After making so many parts, printing a ton of denture teeth and bases, and assembling them, we’ve come up with three techniques for an aesthetic 3D printed denture. What we want is to avoid some of the outcomes of today’s digital dentures, like products with an opaque base or gingiva, which is a bit of a mess in my opinion. Or you come about a semi transluscent base which leaves the roots exposed, and lastly when you use the splinted tooth workflow you can end up with a bulky interproximal connection. And since the papillae are a really thin printed parts, it’s really easy to see the teeth connecting, looking unnatural.”

The three aesthetic denture techniques suggested by Wainwright include:

  1. Natural gingival connection and cervical margin are based on the CAD output for optimal result
  2. Splinted arch ease of assembly without a bulky interproximal
  3. Life-like gingiva, inspired by “Brazilian Dentures”

Wainright suggests that for his first aesthetic dental technique, users can control the depth of penetration of the tooth as well as the angle it comes in or goes out, by using a new function in the 3Shape Dental System CAD software (version 2018+). The option is called coupling mechanism, and gives the user much more control than before, something which comes in very handy considering that “the more subgingival length the tooth has, the stronger the bond is with the base.” 

“The reason why 3D printed dentures are different than traditionally made dentures is that resins for the base and the teeth are like cousins. When the parts come out of the printer and you wash them, they are almost soft and even sticky, because they are only partially cured, between 25 and 35 percent. But during the final UV curing process, the tooth and the base become one solid part.”

In fact, the dentures specialist indicates that users should cure the combined base and teeth with a handheld UV cure light, moving towards the interior, just to really hold the parts together. Once the user has checked that all the cavities have been filled up and removes any residual base resin, the denture is complete and ready to be submerged for 30 minutes in glycerine at 80 degrees celsius, for a total hour of cure time. At that point, the piece can be finished up with a UV glaze or wheel for a high shine polish.

The second recommended aesthetic denture technique involves a splinted arch ease of assembly without a bulky interproximal.

Wainright explained that he sets up “these cases up in CAD so they are 100% splinted together because it is so much easier to have consistent placement of teeth, instead of doing it one by one which can be labor-intensive. I first export the arch splinted, but the question here is how to make the connection between the teeth interproximally look natural, especially when you have a very thin papilla. So before assembly, during our support removal part of the process, we’ll take a cutting disk and reduce the interproximal connection down from the cervical margin up towards the incisal. This really helps the aesthetics of the denture without worrying about any spaces.”

He also recommends that during the assembly process, users can easily brush in gingiva resin in the spaces to make sure there is no air, gaps or voids, maintaining the strength.

“Keep your eye out for bubbles,” repeated Wainright many times, explaining that “if you do minimal interaction to get the resin in the spaces, it really reduces the bubbles.”

He also added that the key is to “flow in more resin at first, instead of just wetting it, and when it’s squeezed together it will flow into that area. Finally, the overflow can be wiped away with a gloved finger.” 

“It seems quite simple but this are the things we learn over time. I repeated many of these processes a handful of times and got better, today it may take me up to 10 minutes at the most to finish up one denture. Moreover, if you think about the soft touch supports in the Form 3, post processing will be even easier, as anyone will be able to rip them off and add very little finishing to the product.”

For the last aesthetic denture technique, Wainwright suggested following up the “Brazilian dentures” example, which offers an inspiring way to create life-like gingiva. He says he noticed Brazilians have become experts in creating dentures, adding translucent resins in the base that allow for the patient’s own gingiva color to show through. He proposed the LP resin Formlabs resin is also quite translucent, but when tested on a model or patient’s mouth, “it adds a nice depth to the gingiva itself giving a reflection of light useful in aesthetics.”

“When the denture is seated intraorally, the patient’s natural gingiva shows through making the prosthetic come to life.”

Formlabs is known for creating reliable, accessible 3D printing systems for professionals. According to the company, in the last decade, the dental market has become a huge part of the company’s business and that Formlabs is trusted by dental industry leaders across the globe, “offering over 75 support and service staff and more than 150 engineers.” 

It has shipped over 50,000 printers around the world, with tens of thousands of dental professionals using Form 2 to improve the lives of hundreds of thousands of patients. Additionally, using their materials and printers in more than 175,000 surgeries, 35,000 splints and 1,750,000 3D printed dental parts. One of the aims at Formlabs is to expand the access to digital fabrication, so anyone can make anything, this is one of the reasons why the company is making webinars, to help everyone get there.

Wainright also revealed that Formlabs will be releasing two new denture bases, RP (reddish pink) and DP (dark pink), as well as two new denture teeth shapes, A3 and B2, that will complement the already existing A1, A2, A3.5, and B1. 

If you are a big fan of webinars, make sure to check out more at 3DPrint.com’s webinars under the Training section.

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[Images: Formlabs]

The post Formlabs Tells Us How to Make Good Looking 3D Printed Dentures appeared first on 3DPrint.com | The Voice of 3D Printing / Additive Manufacturing.

3D Printing News Sliced, $11M project call, SLM Solutions, Aconity3D, Onshape

This edition of our 3D printing news digest Sliced features an $11 million funding pool  for flexible electronics; metal 3D printing’s expansion in the U.S.; life-changing fundraising for 3D bioprinters; mind-boggling 3D printed ceramics and more. Read on for the latest news from NextFlex, SLM Solutions, Aconity3D, Onshape, Bristol Children’s Hospital and Cunicode. NextFlex offers $11 […]

Siemens Releases Solid Edge 2019, Packed with New Tools and Updated Features

Siemens has been delivering its Solid Edge software for several years now, enabling engineers and designers to create in CAD/CAE easily yet professionally. The company has now introduced the latest iteration of the software, Solid Edge 2019, and it reliably includes plenty of new features as well as upgrades to existing ones, in categories including mechanical design, electrical design, manufacturing, simulation, technical publications, and data management.

Users can now reverse engineer imported objects and take advantage of new features such as convergent modeling, generative design, and advanced flow simulation. An impressive array of PCB design tools are also included.

“The global market requirement to develop and deliver increasingly complex products in shrinking timeframes has created many new challenges for our customers, as well as new opportunities to differentiate,” said John Miller, Senior Vice President, Mainstream Engineering, Siemens PLM Software. “I’m confident that the integration of leading technologies and the next-generation design capabilities delivered in the Solid Edge 2019 portfolio will empower our customers to innovate in the new era of digitalization.”

New tools are available for convergent modeling, allowing engineers to incorporate mesh models directly into their workflows. The tools also support milling, casting and molding of generative designs, so that users can model and simulate the entire process, not just the final product. On the electrical engineering side of things, Solid Edge Wiring Design offers design tools that can be used to rapidly create and verify the flow of wiring through electrical systems.

Solid Edge Harness Design adds harness and formboard design using automated part selection, verification and report generation. In addition, Solid Edge PCB design enables the intuitive creation and schematic capture of printed circuit board layouts, including sketch routing, hierarchical 2D/3D planning, and ECAD-MCAD collaboration.

Solid Edge CAM Pro is a new system that allows users to program CNC machine tools, and supports both simple NC programming and high-speed, multi-axis machining. On the additive manufacturing side of things, automated print and color preparation allow designs to be sent directly to the 3D printer. Multi-color and multi-material 3D printing are both supported.

P&ID Design and Solid Edge Piping Design tools offer improved modeling, simulation, and automated placement of piping systems. These systems allow for automated 3D piping design and fully automated isometric drawing output for plant design. There is also a 3D parts library included. These tools, according to Siemens, can help reduce design errors and ensure efficient piping design in the oil and gas industries.

General improvements include better control over shapes, weight and strength. Free cloud-based collaboration tools are included as well, allowing users to work in real time from anywhere with browser-based access to CAD files.

You can learn more about the new features here, as well as check out buying options. Several discount bundles are available at the moment, for a limited time.

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[Source: Graphic Speak/Images: Siemens]