November 9, 2017
by Mark Lin, BSc, DDS, MSc (Prosthodontics), FRCD(C); Michael Wang, Laboratory Associate; Julia Hang, Laboratory Associate
What Is Digital Solution and Why Should I Integrate It Into My Dental Practice?
The need to implement a digital solution in today’s age has become ever more apparent with our society’s desire to be on the cutting edge. You can incorporate cone beam machines into your practice to both plan the implant position, diameter, length and fabricate your own milled surgical guides. A milling unit can also be incorporated into the practice to fabricate same day restorations. For this article, the focus will be on intraoral scanners and potential options for your practice.
Intraoral scanners will allow dentists to be able to skip the conventional impression process entirely by generating intraoral scans that can save chair time and create a more comfortable experience for patients. Making a traditional impression can at times be a tedious process with the possibility of the patient gagging and inaccuracies occurring. If the laboratory needs additional information to be captured within the impression, the patient needs to be called back to redo the impression which can be painstaking. The use of an intraoral scanner can reduce the bulk of these issues creating a more accurate digital impression, improving the clinical experience for the patient and producing optimal final prosthetics.
There are two types of scanners available on the market; LED scanners which require a powdered spray to detect all the details intraorally and laser scanners. A digital model is created from the scan and the file is sent directly to the lab for processing. There are two types of modelling systems being used currently, one being the Stereolithography apparatus (SLA) and milling. SLA is a 3-D printing formed in layers using photo polymerization. Milled models are created from a pre-cured polymer puck inserted into a milling machine, where excess material is carved out until a precision model is complete.
Table 1: Common Issues with PVS Impressions Charts
The Digital Impression Workflow
Step 1: Intraoral Scanning
We recommend that you inform your patients of the new advances you have made in your practice. The intraoral digital scanning systems will decrease patients chair time and increase their comfort, and confidence in the precision of their final prosthesis.
Be sure to confirm the amount of intraoral data that is required when scanning, insufficient data will lead to inaccuracies in the scan. Some factors can distort a digital scan that you must be mindful of, such as blood or excess saliva. Retraction cords are preferred to give the most accurate scan of the prepared margin. There will be rare instances where a physical bite registration is needed for the laboratory to fabricate free end cases or difficult bites.
Step 2: Digital Fabrication
With the digital scan captured you can either send it to a lab to fabricate the restoration or have it designed in your office with a CAD/CAM designing software and milling unit. With an in-house lab, CAD/CAM designing software and a milling unit may be of interest to you, the benefit being the ability to design and produce same day restorations for your patients.
Step 3: Delivery
Upon delivery of the prosthesis, the marginal fit and occlusion will be precise with little to no interproximal or occlusal contact adjustments. The amount of cases that need to be redone are also minimized due to the increased accuracy of the digital impressions. See following page for a chart comparing three of the popular intraoral scanners available:
The Advantages to Digital Impressions
Speed and Accuracy
• No need to size trays or fabricate customs trays.
• Immediate alterations to scan compared to having to redo the impression.
• Instant chair side communication with lab while the patient is in the chair.
• Improved treatment and comfort.
• No risk of gagging or allergic reaction to impression material.
• Patient is engaged in the treatment process through chair side visuals.
• Reduced revisits for remakes of prothesis.
• Intraoral scanners are designed ergonomically and lightweight.
• Quick convenient scanning, elevating rebooking of patients for new scans.
• Precision digital measurements improve the quality of your dentistry.
• Improves communication with laboratories.
• Virtual measuring tools help guide you with tooth design.
• Easy access to digital records stored on file, reducing the physical space needed for storing and finding stone
• The case can be started immediately upon receiving the scan.
• Same day crowns can be fabricated with in-house milling.
• Digital scans remove the possibilities of voids and bubbles
• If a digital model is inaccurate, scans can immediately be redone chairside.
• Digital scans remove the possibilities of voids and bubbles which minimizes crown seating and adjustments.
• Cost of impression materials and trays are cut down.
Parameters to Consider with Digital Impressions
Until recently it was not possible to do full-arch impressions. digitally. Unfortunately, a full-arch digital impression still requires more time than a conventional impression technique. Fabricating restoratives can be limited, especially with implant impressions because not all digital systems support every implant platform available in the market.
When considering buying a digital scanning system for your practice, you may need to consider all aspects of this technology. You will need to purchase materials, components, software subscription fees, and maintenance fees. Communicate with your local sales representatives for more details and potential options. Assessing your practice’s output of restorations will be a helpful factor in determining whether you will be able to offset the initial investment.
Lab support plays a vital role with digital impressions. Having a good lab leads to better dentistry which improves patient satisfaction. Find a laboratory that you can work with either offsite or in-house that accepts compatible digital file formats. Below are two Toronto based labs that we interviewed:
1. Shaw Laboratories offer services for a wide variety of intraoral scanners, making them a potential option for your digital solution. They have the software to support files from the following intraoral scanners. The Itero, Trios, 3M True Definition, CEREC In Lab, Nevo E4D and the Carestream. Shaw Laboratory accept digital scans for dentures, partial dentures, orthodontics, crown, bridges and implant restorations. They have recorded the measurement of accuracy tolerance of the definitive prosthesis up to 16 microns.
2. Durban Dental Laboratories have software to accept s STL files from Itero, Planscan, CEREC, 3 Shape Trios and Carestream systems. Durban also offers a scanning service to dentist who do not own a digital scanner. A qualified Digital Dental Assistant will bring their portable scanner to your office and scan a case. It is also an opportunity to determine if investing in an intraoral scanner is the right choice for the clinic. Other services include implant placement planning for cosmetically driven cases.
Please contact your local laboratories to inquire about their capabilities with digital scans.
How Do I Begin Implementing a Digital Solution?
If you want to begin implementing a digital solution, be prepared to invest. Another crucial factor in your decision making should be how the practice will incorporate the new technology and overcome the inevitable learning curve. Most companies that sell the digital impression systems offer in-office training to provide knowledge on how to use the equipment properly and effectively. It is critical that you do your research before purchasing an intraoral scanner to ensure you are making the most appropriate purchase for your practice. Here are some questions you should be asking;
• Do you truly understand the advantages of going digital and how this will benefit your practice?
• Do you have a support team in place to guide you through the learning curve?
• How experienced is your lab with the digital workflow?
With all the intraoral scanners available makes choosing a scanner difficult. Below are two popular examples of scanners currently in the market.
1. The Carestream CS 3600 intraoral scanner, with its dedicated implant-borne restorative workflow (PDIP), saves times and leads to more predictable clinical outcomes with industry leading accuracy. For example, the quality of complex cases with multiple scan bodies is significantly improved with an innovative scan body area selection tool that reduces the chance for image mismatch that can occur when using multiple scan bodies. The CS 3600 is part of an open system, meaning it’s STL files can be easily exported into third-party CAD programs for everything from custom abutments to the fabrication of surgical guides.
2. The Dental Wing intraoral scanner was specifically designed with the needs of the user and patient in mind. It provides unique advances in infection and cross-contamination control by enabling the user to control the scanner through the use of hand gestures and voice control. The powder-free hand-piece is one of the smallest available on the market and ergonomically designed to reduce hand fatigue. If space or portability is a concern, this scanner is also available in mobile format that has a smaller footprint and can easily be transported. OH
Oral Health welcomes this original article.
Dr. Mark H. E. Lin, BSc, DDS, MSc (Prostho), FRCD(C), graduated from the University of Detroit Mercy for his dental program. He then completed a one-year General Practice Residency program at the Miami Valley Hospital in Dayton, Ohio.
He practiced general dentistry for 13 years and then returned to complete his post-graduate training in the specialty of prosthodontics at the University of Toronto. He maintains a full-time specialty practice as a prosthodontist at Dr. Mark Lin Prosthodontic Centre.
Michael graduated in 2013 from George Brown College in the Dental Technology Program and has been working with Dr. Mark Lin Prosthodontic Centre since 2010. He is an energentic lab associate who specializes in teeth in a day dentures, same day teeth in a day conversion, complete dentures, partial dentures,orthodontic appliances and Cerec Bluecam CAD/CAM designing.
Julia is the supervisor of Lin Laboratory Ltd. She graduated in 2012 from George Brown College in the Dental Technology Program and has been working with Dr. Mark Lin Prosthodontic Centre since 2011. She is highly committed to the excellence of all prosthesis produced for the patients’ comfort, esthetics and function. Having experience in teeth in a day dentures, same day teeth in a day conversions, implant supported prosthesis and multiple CAD/CAM designing systems (ie. Cerec Blue-
cam, Nobel Procera and 3Shape).
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