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Digitising your implant practice

CBCT volume to aid in planning for mandibular implant placement. (Image: Dr Ross Cutts)

Thu. 3. May 2018

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Undoubtedly, digital dentistry is the current topic. Over the last five years, the entire digital workflow has progressed in leaps and bounds. There are so many different digital applications that it is sometimes difficult to keep up with all the advances. Many dentists are excited about the advantages of new technologies, but there are an equal number who doubt that the improved clinical workflow justifies the expense.

I have many times heard the argument that there is no need to try to fix something that is not broken. It is so true that impressions have their place and there are certainly limitations to the digital workflow that anyone using the technology should be aware of. For me, however, the benefits of digital far outweigh the disadvantages. In fact, the disadvantages are the same as with conventional techniques.

Chairside CAD/CAM single-visit restorations have been possible for over 20 years, but it was only recently that we became able to mill chairside implant crown restorations after the release of Variobase (Straumann) and similar abutments. I made my first CEREC crown (Dentsply Sirona) back in 2003 with a powdered scanner, and the difference from what I remember then to how we can make IPS e.max stained and glazed restorations (Ivoclar Vivadent) now is amazing.

An investment not an expense

The results of a survey regarding the use of CAD/ CAM technology were published online in the British Dental Journal on 18 November 2016. Over a thousand dentists were approached online to take part in the survey and the 385 who replied gave very interesting responses. The majority did not use CAD/CAM technology, and the main barriers were initial cost and a lack of perceived advantage over conventional methods.

Thirty per cent of the respondents reported being concerned about the quality of the chairside CAD/CAM restorations. This is a valid point. We must not let ourselves lose focus that our aim should always be to provide the best level of dentistry possible. For me, digital dentistry is not about a quick fix; it is about raising our performance and improving predictability levels by reducing human error.

In the survey, 89 per cent also said they believed CAD/CAM technology had a major role to play in the future of dentistry. I really cannot imagine that once a dentist has begun using digital processes that he or she would revert to conventional techniques.

What is digital implant dentistry?

Many implant clinicians have probably been using CAD/CAM workflows without even realising it, as many laboratories were early adopters, substituting the lost-wax technique and the expense of gold for fully customised cobalt–chromium milled abutments (Fig. 1).

One of my most important goals in seeking to be a successful implantologist is to provide a dental implant solution that is durable. We have seen a massive rise in the incident of peri-implantitis and have found that a large proportion of these cases can be attributed to cement inclusion from poorly designed cement-retained restorations (Fig. 2). Even well designed fully customised abutments and crowns can have cement inclusion if the restoration is not carefully fitted (Fig. 3). This has led to a massive rise in retrievability of implant restorations, with screw-retained crowns and bridges now being the goal. However, making screw-retained prostheses places even greater emphasis on treatment planning and correct implant angulation.

With laboratories as early adopters, we have been milling titanium or zirconia customised abutments for over ten years (Fig. 4). What has changed recently in the digital revolution is the rise of the intraoral scanner. We now have a workflow in which we can take a preoperative intraoral scan and combine this with a CT scan using coDiagnostiX (Dental Wings) in order to plan an implant placement accurately and safely. We can also create a surgical guide to aid in accurate implant placement, have a temporary crown prefabricated for the planned implant position and then take a final scan of the precise implant position for the final prosthesis.

Accuracy of intraoral scanners

Figures 4 to13 show the workflow for preoperative scanning, which includes the implant design, guide fabrication and surgical placement of two fixtures. Intraoral scanners have improved over the last few years, and their accuracy and speed provide a viable alternative to conventional impression taking. The digital scan image comes up in real time and you can evaluate your preparation and quality of the scan on the screen immediately. Seeing the preparation blown up in size no doubt improves the technical quality of your tooth preparations. The scan can then be sent directly to the laboratory for processing.

While we do not think of intraoral scanners as being any more accurate than good-quality conventional impressions, there are many benefits of scanning, such as no more postage to be paid for impressions, vastly reduced cost of impression materials, almost zero re-impression rates and absolute predictability.

Of course, there are steep learning curves with the techniques, but once a clinician has learnt the workflow, there really is no looking back.

We have three different scanners in the practice: the iTero (Align Technology), the CEREC Omnicam (Dentsply Sirona) and the Straumann CARES Intraoral Scanner (Dental Wings; Fig. 14). The CEREC Omnicam is fantastic for simple chairside CAD/CAM restorations, such as IPS e.max all-ceramic restorations on Variobase abutments. For truly aesthetic results, we, of course, still have a very close working relationship with our laboratory, but, undoubtedly, patients love the option of restoration in a day. Being able to scan an implant abutment and then an hour later (to allow for staining and glazing) fitting the definitive restoration is a game changer. Patients also love watching the production process as they see their tooth being milled from an IPS e.max block.

Figures 15–19 show the production process, including the exposure of the implant, the abutment seating, the scan flag on top of the abutment, the healing abutment during fabrication and the delivery of the final prosthesis. However, for more than single units or aesthetic single-unit cases, we use the iTero and Straumann scanners. The latter we have only had at our disposal since February. While it is a powdered system at the moment, this is due to change this month. Particularly with implant restorations, the need to apply a scanning powder is a limitation, owing to a lack of moisture control contaminating the powder. The technology, however, is superb, as is the openness of the system, which provides the advantage of being able to export files into planning software. A colleague of mine even uses it for his orthodontic cases now instead of wet impressions.

We invested in the iTero scanner five years ago and have used it for everything, from simple conventional crowns and bridges to scanning for full-mouth rehabilitations. When fabricating definitive bridgework, we use Createch Medical frameworks for screw-retained CAD/CAM-milled titanium and cobalt–chromium frameworks. Even though intraoral scanning appears extremely reproducible and accurate, I still use verification jigs where needed to ensure our frameworks are as accurate as possible. There are many intricacies that we consider and tips and techniques that we employ to make the scans more accurate that we have developed over time. The closer the scanbodies are together, the more accurate the scan is. Also, the more anatomical detail, such as palatal rugae or mucosal folds, the better the scans can be stitched together.

Figure 20 shows a CBCT volume to aid in planning for mandibular implant placement (Fig. 21) and realising the implant placement. We exposed the fixtures and placed Straumann Mono Scanbodies (Fig. 22). Then, we took an iTero scan of the fixtures in situ (Fig. 23) and made a verification jig from this (Fig. 24) to ensure passive implant positioning. The iTero models were made (Fig. 25) and a Createch titanium framework was used to support porcelain in a screw-retained design (Fig. 26). The last two figures show the excellent outcome and accurate framework seating (Figs. 27 & 28).

Choosing your workflow

There are many different systems on the market now, each offering a one-stop shop. If you are considering investing in a digital scanner, then take some advice from colleagues. One of the most important things is to ensure the system you opt for is an open one that allows you to extract the digital impression data into different software. We extract our files into CT planning software, model production software, chairside milling for stents, temporaries and definitive restorations, and now orthodontic planning software. I am convinced there will be yet more advances with time. The size of the camera is critical—some can be very cumbersome—and it is worth asking the salesperson what developments are underway.

Some companies are more on the cutting edge than others. My favourite at the moment is the Straumann scanner. Its design is light and user-friendly and it synchronises perfectly with implant planning software coDiagnostiX. Furthermore, while it offers a chairside milling unit, it also synchronises perfectly with my laboratory for larger cases.

To conclude, digital implant dentistry is the future and so why not take advantage of it and help improve your clinical outcomes?

Editorial note: A list of references is available from the publisher. This article was published in CAD/CAM - international magazine of digital dentistry No. 03/2017.

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UltraGLOSS (Asiga) allows users to print clear parts directly with a glossy, pre-polished surface. (All images: Jeroen Klijnsma)

Wed. 27. March 2024

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As a certified dental technician, I have worked in, managed and owned several laboratories around the world. This has exposed me to many different analogue, digital and crossover techniques. Even though digital technology has been widely available in our industry for over two decades, the uptake and trust in this technology are still fairly low compared with analogue methods. Even if digital technology is available in a clinic or laboratory, the knowledge of it is often limited. Knowing the benefits and limitations and especially how to operate the technology as efficiently as possible are key.

Fig. 1: The new UltraGLOSS resin tray (Asiga).

Fig. 1: The new UltraGLOSS resin tray (Asiga).

I am personally a huge fan of additive manufacturing (3D printing) and the possibilities this technology offers. The high accuracy, low entry costs and minimal amount of geometric limitations in our manufacturing processes make 3D printers our best equipment in this modern world. In our fully digital dental laboratory, we have eliminated traditional plasterwork, negating the need for investment in a plaster room. 3D printing has taken over and allowed us to create the highest quality dental models and dental appliances every single time.

If we look at the hardware of affordable 3D-printing systems, there have been few jaw-dropping innovations. Recent years have been dominated by innovations in 3D-printing resins. Consider biocompatible resins and especially hybrid resins for denture bases. Hybrid resins, which are biocompatible US Food and Drug Administration Class II medical devices, now allow us to print long-term (permanent) approved restorations. In recent years, how we manufacture night guards and splints has evolved dramatically. However, the tedious labour of manual adjustments or manual polishing is still required.

When Asiga asked me to try a new type of resin tray that would eliminate or minimise manual post-processing, I was initially sceptical. How could just a different tray make such a difference? After printing my first splint with this new tray, I knew it was a game-changer and one of the best new products on the market. Let me introduce you to the new UltraGLOSS resin tray (Fig. 1). The outcome of printing with this tray is a smoother finish of the printed object. A trick is to increase the number of layers, making the individual layer height smaller and thus resulting in fewer visible layers. The magic of the tray does the rest. We print using our MAX UV printer (Asiga), but UltraGLOSS trays are also available for its big brother, the PRO 4K series. In the following paragraphs, I will explain our processes of manufacturing splints.

Data recording

In order to digitally design a night guard or splint, we need to have a digital recording of the oral cavity, specifically of both arches and a bite registration. This can be done in one of three ways:

  • taking a traditional impression, including pouring a plaster model and then scanning the model with a desktop scanner;
  • taking a traditional impression and directly scanning that impression with a desktop scanner; or
  • taking a digital impression using an intra-oral scanner.

In this case, an as-yet-unreleased intra-oral scanner was used (Fig. 2). A spacer or leaf gauge is used to record an open bite in centric relation independent of tooth contact. In this position, the mandible is restricted purely to rotary movement. From this unstrained, physiological position, the patient can make vertical, lateral or protrusive movements. We only accept scans with an open occlusion, as virtual opening (static or dynamic) of the bite might result in incorrect interpretation of patient’s condylar or occlusal guidance and bite.

Fig. 2: Intra-oral scan on the screen.

Fig. 2: Intra-oral scan on the screen.

Fig. 3: Design of the splint using the Splint Studio CAD program (3Shape).

Fig. 3: Design of the splint using the Splint Studio CAD program (3Shape).

Fig. 4: During the design of the splint, if we add material to the palatal gingival margins, we avoid any local pressure and increase the comfort when the splint is worn.

Fig. 4: During the design of the splint, if we add material to the palatal gingival margins, we avoid any local pressure and increase the comfort when the splint is worn.

Fig. 5: All splints designed in our laboratory have canine extensions for additional retention and to help avoid tipping during articulation.

Fig. 5: All splints designed in our laboratory have canine extensions for additional retention and to help avoid tipping during articulation.

Order form set-up

After receiving the scans, we start designing the splint using the Splint Studio CAD program (3Shape). In our order form (Fig. 3), we select it as a digital impression and select the upper jaw. Next, we select the option to design a splint and the material we would like to use. We print our splints with KeySplint Soft (Keystone Industries). After we have set up the order form, we import the intra-oral scans and open Splint Studio.

CAD

Once Splint Studio is open, we confirm the given bite and select the path of insertion. Here, we can also add or remove space in the block-out stage to determine whether the splint needs to engage more or less. By adding material to the palatal gingival margins, we avoid any local pressure and increase the comfort when the splint is worn (Fig. 4).

The most common designs in our laboratory are Michigan or flat-plane splints. However, all of them have canine extensions for additional retention and to help avoid tipping during articulation (Fig. 5).

Fig. 6: View and position of the splint to be printed (Asiga Composer).

Fig. 6: View and position of the splint to be printed (Asiga Composer).

Fig. 7: Close-up view and position of the splint to be printed (Asiga Composer).

Fig. 7: Close-up view and position of the splint to be printed (Asiga Composer).

Fig. 8: Printed splint.

Fig. 8: Printed splint.

Printing set-up

There are many ways we can set up splints, but the goal is to minimise or even eliminate polishing after post-processing. A splint-nesting position close to horizontal can result in inaccurate prints, depending on the printer, and requires more manual post-processing. We put in a huge effort to design the perfect splint and placing supporting pins on the occlusal surface would undo much of our work as well require more manual post-processing.

Orientating the splint near vertically has the benefits of the splint being self-supporting, of a smaller surface area and therefore less pulling force, and of a smaller chance of visible printed layers on the occlusal surface. For positioning the splint vertically, we have two options: placing either the anterior or the posterior area towards the build platform (Fig. 6). Each has their own benefits, and the choice depends upon what suits you best and whether you prefer to perform a final polish.

The advantage of printing with the posterior downwards is that we do not need supporting pins and therefore no manual finishing is required, except for the area touching the build platform. A disadvantage can be that we need two areas to print successfully, going from both posterior areas towards the anterior area (Fig. 7).

Most of our clients prefer a highly polished appliance, so we print mainly with the anterior area downwards to minimise the risk of a failed print. We see the main benefit in the massive time reduction in our polishing processes. Our team is now spending less than half the time polishing than they did before, as the splints come out much smoother and shinier.

Printing time

When printing in a vertical position, we can fit more splints on a build platform, but it increases the printing time. The printing time is also increased by printing with an UltraGLOSS tray at 50 μm to achieve the best smooth surface. However, based on our time management in our manufacturing processes, we recommend starting printing splints at the end of the day.

They will be finished during the night and ready to take out of the printer in the morning. Manufacture during the night and if anything goes wrong or there is an urgent case, you can print that during the day. This advice would be the same if you were performing subtractive manufacturing with a milling machine with a material loader or changer.

Washing

After printing (Fig. 8), we remove any excess material by washing it in isopropyl alcohol. We clean our splints in an ultrasonic cleaner and have a pre-wash and post-wash container filled with alcohol. These containers are widely available. We use individual cleaning solutions for each material, so we do not have any cross-contamination or lose our biocompatibility classification. Because we use an ultrasonic cleaner and not a stirring cleaner, the splints do not slam and rub against the cleaning containers and therefore the surfaces are not damaged and the splints retain their transparency. 

Fig. 9a: Post-processed splint.

Fig. 9a: Post-processed splint.

Fig. 9b: Splint on the model.

Fig. 9b: Splint on the model.

Fig. 9c: Occlusal view of the splint.

Fig. 9c: Occlusal view of the splint.

Light polymerisation

After carefully cleaning and drying the splint, we give it a final light polymerisation. We have different light polymerisation units that are all validated for use with KeySplint Soft. However, we have had better results with those with which we are able to remove the oxygen and thereby avoid an oxygen inhibition layer. We have achieved the best results with our Otoflash G171-6 (NK-Optik; with nitrogen connection) and our Straumann/Rapid Shape vacuum polymerisation unit (Fig. 9).

Polishing

To achieve a highly polished splint, we remove the supporting pins using a Scotch-Brite wheel (3M) and then use pumice on a lathe to smooth the splint where required. We finalise the splint by giving it a high-shine buff and a proper steam clean (Fig. 10). I do have to emphasise that, the more we work with the UltraGLOSS tray and learn how to optimise the post-processing, we foresee that manual polishing will soon be something of the past.

I have been asked whether UltraGLOSS will work with every material. Technically, the answer is yes. We can print everything with these wonderful trays. However, you have to ask yourself whether printing a model or custom tray at 50 μm would be of any real added value. In contrast, printing denture bases with such a level of detail would be of tremendous benefit, as there will be less manual finishing. Therefore, I am a firm believer that the UltraGLOSS printing technique is an absolute winner and we all benefit, regardless of how we would like our products to be finished.

Figs. 10a–c: Ready splint in patient’s mouth.

Figs. 10a–c: Ready splint in patient’s mouth.

Fig. 10b

Fig. 10b

Fig. 10c

Fig. 10c

Editorial note:

This article was published in 3D printing—international magazine of dental printing technology vol. 3, issue 2/2023.

3D printing 3Shape Asiga Digital dentistry Splint UltraGLOSS

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