One of the primary reasons I embraced CAD/CAM dentistry 20 years ago was the promise that the chairside digital workflow offered in exercising more control over every aspect of the restorative process. Even today, the idea of creating quality dental restorations in one visit for my patients is quite appealing.
I have found, however, that in order to cause the vision to crystalize into a beautiful IPS e.max CAD restoration for a patient, I need more than just the furnace required to crystalize the restoration. I need a clinical technique that is precise, repeatable and efficient.
While the CAD/CAM workflow is composed of many steps, each essential in their own respect, this “quick tip” will focus on establishing clear, clean and dry preparation margins in support of the digital impression and restoration bonding processes.
Preparation before preparation
Before we spin up the turbine on the handpiece, two steps will lay the foundation for success. The first is to evaluate the patient’s periodontal status and consider any treatment required to achieve periodontal stability, because we know that excessive bleeding during the procedure will place the outcome at risk. The second is to consider whether the preparation margins are to be subgingival and, if so, place a length of dry, knitted retraction cord (Knit-Pak, Premier Dental Products, Plymouth Meeting, Pa.).
As a guide for what size cord to use, determine the minimum probing depth in the region of the sulcus that will adjoin a subgingival margin and then subtract that number by “1” to arrive at the cord size. So, for instance, if the minimum probing depths for the facial and interproximals for the teeth to be veneered was 2 mm, then the #1 cord was placed. It is important to place the required cord prior to beginning the preps as they will provide some protection against soft-tissue trauma imparted by the bur during preparation.
Another hedge against insulting the gingiva during preparation is to use a finishing grit diamond bur (round-end taper 782.8F, Premier Dental Products) to finalize the position of subgingival margins. Even with these hemorrhage prevention measures, some bleeding may occur and/or the tissues may become edematous during the preparation process. If nothing is done to mitigate the bleeding or edema, the quality of the digital impression and, later in the procedure, the adhesive bond will both be compromised.
The next line of defense against these clinical complications is application of a hemostatic retraction paste for two minutes (Traxodent, Premier Dental Products). This is followed by copious rinsing and thorough drying. When drying the area, care should be taken to thoroughly dry each sulcus as the cord in place acts as a wick for moisture, and it will require more time to dry than the teeth themselves.
It is also helpful during the procedure to use a soft-tissue retraction device to gain better access and to prevent the retraction paste from being displaced during the two-minute material action period (Comfort-View, Premier Dental Products).
After rinsing and drying, one should inspect the margins carefully and expect to clearly see them from the occlusal and/or facial aspect.
At this point, the digital impression may proceed with ease. In the case pictured, the veneer preparation impression was captured using the Planmeca PlanScan scanner (Planmeca USA, Roselle, Ill.). During live scanning, the margins are clear and visible on the screen, just as they were in the mouth.
A quality digital impression will carry over to a higher degree of confidence in subsequent steps, such as marking the margins on the virtual model.
Preparation is critical to achieving the final result for a patient. While the design process is not shown here, you can see the precision of this patient’s restoration, milled with Planmeca PlanMill40.
Re-application of Traxodent (Premier Dental Products) prior to bonding, using the same technique previously described, will help to ensure that the marginal areas of the teeth are dry and exposed.
The combined use of a general soft-tissue retractor (Comfort View), dry cord (Knit-Pak) and hemostatic retraction paste (Traxodent), described herein, have the combined effect of supporting an ideal treatment outcome as illustrated in the post-treatment appearance of these veneers.
While this clinical workflow was presented in the context of chairside digital CAD/CAM dentistry using the Planmeca FIT system (Planmeca USA), one should appreciate its application for all types of digital or physical fixed restorative impressions as well as adhesive bonding procedures.
What is a social network? For as long as humans have walked the earth we have been social creatures. We pride ourselves on family and form groups in order ...
More than 30 years ago, Dr. Daniel S. Kim, then a young prosthodontist in training, was assigned a patient who had lost a crown. Kim found that the dentin ...
An accurate master impression is essential to a quality indirect dental restoration. We operate in an area where as little as 30 microns can mean the ...
KOBLACH, Austria: Simple restorations can be fabricated quickly and in high quality directly in the dental practice using the Ceramill DRS Production Kit+ ...
LONG BEACH, Calif., USA: Moving beyond the proven tech and best-selling success of the i700 intraoral scanner, today MEDIT is announcing the release of the ...
Since 1982, dentist Svend Carlsen has used various differing intra-oral scanners for taking impressions digitally. Carlsen spoke about developments in ...
NEW YORK, N.Y., USA: As announced at IDS 2015, CEREC Omnicam and the new CEREC Ortho Software can be used to submit digital impressions for Invisalign clear...
OXNARD, Calif., USA: Well-known dentists, hygienists and dental assistants in the U.S. have come together to form a new coalition called Support Clean ...
If you read my articles regularly, you might have noticed that I dedicate a fair amount of space to telling you how you should be addressing shortfalls in ...
KATIKATI, NEW ZEALAND: Some people think Stegosaurus — that archetypal dinosaur with the exaggerated spines. Others think Jaws — this ...
Live webinar
Thu. 18 July 2024
8:00 PM EST (New York)
Live webinar
Tue. 6 August 2024
6:00 PM EST (New York)
Live webinar
Tue. 13 August 2024
7:00 PM EST (New York)
Live webinar
Wed. 14 August 2024
12:30 PM EST (New York)
Live webinar
Wed. 21 August 2024
9:00 AM EST (New York)
Dr. Jim Lai DMD, MSc(Perio), EdD, FRCD(C)
Live webinar
Wed. 28 August 2024
8:00 PM EST (New York)
Live webinar
Mon. 2 September 2024
5:00 AM EST (New York)
To post a reply please login or register