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Tolerance – the key to a good dental implant prosthetic

Attention to tolerance is the vital first step in an implant procedure.

Kostas Zarras, Elos Medtech’s Global Product Manager, shares his experience in the area of tolerance and how it can affect the success of dental implants.  Kostas is a former dental lab technician who recognizes how important tolerance calibration and best practices are for accuracy in an implant procedure.  

Why is tolerance such an important factor?

Kostas Zarras:  Precision is an absolute necessity. An accurate fit of the restoration is obviously important for the implant to be able to withstand the high bite force from normal chewing of food. The interplay of the screw force within the restoration and the bite force must be precise to ensure patient comfort and the longevity of the implant. In a sense, it’s basic mechanics, which we have outlined in Elos Medtech’s Forces eBook.

What about tolerance in manufacturing titanium implant components?

KZ:  The manufacturing process involves the latest digital technology and equipment to deliver the precise dimensions of an implant base or analog. You must have this tight tolerance — measured in micrometers (μ)— or things could go wrong for the patient. Depending upon the type of base or analog used and the particular phase of the implant process, the tolerance level may be just a fraction of that of a human hair.

Our attention to tolerance calibration when manufacturing is a determining factor in the success and longevity of an implant procedure. Precision is a key word here and the manufacturer of titanium implant bases and analogs bears around 90% of the responsibility for delivering the needed precision of an implant procedure as a whole.

Our expertise and experience, based on committed R & D efforts, have resulted in the manufacture of titanium — which is an excellent biocompatible material — implant bases and analogs that enable a perfect fit.

Are there follow-up activities at Elos Medtech?

Yes, we are able to evaluate the results of an extended number of patients each year and share our findings with dental labs and clinics, and our R&D department so they can make any improvements needed.

Where should you point a finger if the crown should de-bond from the titanium base?

KZ:  It could be a misstep at the clinic, or it might be the lab, or it could be both; however, it’s not simply the bonding that can be done incorrectly, but also other steps in the implant process.  

Printer s can be the source of the biggest potential for problems. For instance, the liquid used in 3D printers can contract when cold. Printers also tend to be difficult to clean so maintenance is very important for efficiency. I believe 3D printers will be seeing continuous improvements in the future. Dental labs also use a variety of equipment such as milling machines, sintering furnaces and more, all of which can affect accuracy.

(Image 1) from plaster model to final restoration

(Image 2) the results of 2 different restorations with inaccuracies.

When it comes to the final step, bonding, the tolerance is zero μ. See Elos Medtech eBook on bonding guidelines.

Ultimately, tolerance calibration and adherence to best practices all along the chain are a must in a process that improves a patient’s quality of life.

What are the factors that influence tolerance?

KZ:  There are several factors: tool wear in the machining phase along with the accuracy of manufacturing and the repeated use of machines, and, measuring resolution and any uncertainties in measuring as well as the frequency of measuring. Temperature can also play a role in machining and measuring, and there can be variation in raw materials. Different operators may have different approaches to their tasks. And, of course, all components must be accurately assembled.

What can be done to help ensure success at the lab or clinic levels?

KZ:  You need to have equipment that is up to date.

Once again, around 90% of the precision factors depend on accurate tolerance levels achieved at the manufacturing phase. From there, you have scans and models made at the clinic or the lab. That’s why equipment must be up-to-date, well calibrated and reliable, to ensure tolerance margins are low.

And there are peripheral factors such as temperature, which can contract or expand a crown. It’s not a big problem, but you still must pay attention to it, because you need to minimize a gap to minimize problem potential.

Equipment and materials at clinics or labs should be calibrated according to manufacturers’ recommendations. Scanning and other equipment producers will generally advise them to do so.

Here at the end of the interview, do you have any final good tips for the labs and clinics?

KZ:  Maintain, calibrate, and only use high-quality materials.

Link to video: https://vimeo.com/845229561