Once in a while in the past, I received calls from the dental lab informing me that they were fabricating a crown for one of my patients, but had found that the occlusal clearance was not sufficient. I learned that this is not just my problem.
There are several options to correct this problem: 1) Reducing the opposing tooth at the lab,
2) reducing the abutment tooth at the lab, 3) providing metal occlusion, or 4) performing another preparation and taking a new impression in my office.
Under these circumstances, I preferred to take a new impression, but this meant that I had to call the patient to make an appointment for another impression. For me, this was not only embarrassing, but also a waste of the patient’s time, my chair time, and my materials. After each crown preparation, I usually checked the occlusal clearance using multiple layers of carbon papers or just “eyeballing” it. This was generally adequate for confirming the presence of enough clearance, but, every once in a while, I still did not gauge the clearance correctly. No matter how experienced and accurate my visual perception might be, I realized that there was a chance that it might not work every time without some kind of guide.
I needed an instrument to guide and confirm the occlusal clearance mechanically to create ideal abutments every time for every patient. This avoids all the guesswork and any further waste of costly chair time, which could compromise an otherwise excellent patient experience.
And with that, PrepSure was born.
PrepSure (Patent Pending) comes with 3 different sizes of tips for both mesial and distal to prepare crowns and onlays. The precisely-measured tips have unique shapes to glide along the cuspal waves of the occlusal surface and confirm the occlusal clearance. It also preserves the dental structure by preventing unnecessary reduction of the abutment tooth and helps provide crowns that are significantly less likely to fracture prematurely.
There are 3 sizes of PrepSure tip diameters for all modern crown/onlay materials:
1.0mm - Solid zirconia crown, other ‘monolithic’ materials
1.5mm - PFMs, other bilayered crowns
2.0mm - Porcelain (ceramic)
The 1.0mm mesial (M) tip of PrepSure, placed in the middle of the occlusal surface, checks the occlusal clearance of the mesial half of the abutment reduction for a solid zirconia crown.
With the teeth closed, the mesial (M) tip of
PrepSure is passed freely through the mesial half of the occlusal clearance of the prepared abutment along the cuspal wave surface. This confirms the presence of adequate clearance.
This process is repeated at the distal half with the distal (D) tip of PrepSure, completing the confirmation of the clearance of the distal half of the abutment. Now you are ready to take a traditional or
digital impression for the solid zirconia crown.