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May 2009 | Dental Products Report
Clinical 360°: minimally invasive

A happy half-decade

CAD/CAM technology and its results holding up after 5 years of delivering care.

by Dr. Kelly Blodgett

The set-up

"Dr. Kelly Blodgett has, from his graduation from dental school, been totally committed to Minimally Invasive Dentistry and acquiring the technology needed to implement it. He has previously written on the benefits of CEREC, and in this article he provides you with a long-term analysis of his experiences with one-appointment, long-term restorations.”
—Dr. Joe Whitehouse, Team Lead

In one word I am able to describe my feelings toward my CEREC after five years: Satisfied.

 For figures, see slideshow

Like most dentists, before I purchased my own system I was skeptical about this seemingly fancy “CAD/CAM” technology. When it arrived in my office I was even somewhat skeptical as to whether it would meet my expectations. Would it have technical problems? Would the restorations last? Would the esthetics exceed what I was able to achieve with direct resin or lab-fabricated restorations? Would I really save time while providing a better quality product for my patients? Would a minimally invasive approach be achievable as often as I hoped?

Questions answered
I’m here to tell you that after five years of using my CEREC system from Sirona Dental Systems not only have my expectations been met almost every day, they have been greatly exceeded. Because I realize the majority of dentists are still not using CAD/CAM technology, I would like to share my experiences and the benefits that using CEREC has created in my practice.

Expectation No. 1: Esthetics

At first I had a difficult time conceiving that a monochromatic block of ceramic material would be able to look as good as direct resin or a lab-fabricated restoration. Boy, was I wrong. There are a few reasons the esthetics are so great using CEREC ceramic and resin blocks, including Vita Mark II, EmpressCAD or Paradigm Z100. CEREC inlays and onlays can be characterized with the help of ceramic stains. However, because of the special qualities of the CEREC ceramics (chameleon-like shade adaptation; wide choice of lightness, translucency and color shades), staining is not necessary in most situations.

Additionally, the CEREC ceramics are easy to polish. In most cases the surface finish is similar to that of a glazed restoration. Various studies verify the good shade adaptation of CEREC ceramics. According to the criteria of the California Dental Association (CDA), 87% of the restorations were rated as excellent. According to the U.S. Public Health Service (USPHS), the surface characteristics and shade adaptation of all the tested restorations were judged to be excellent or clinically good. But the greatest reason, in my opinion, is that I no longer just grind down every tooth with a crack for a crown, but thoughtfully approach each tooth and try to conserve as much sound enamel as possible.

So often, I have been able to retain sound buccal cusps that keep the patient’s tooth looking like…his or her own tooth. It is difficult to beat the esthetics of the patient’s own tooth. See Figs. 1-2 for a pre-operative view and a look at the CEREC restoration 4.5 years post-op.

Expectation No. 2: Longevity
Before purchasing my CEREC system, I performed thorough research investigating all the information I could find. I particularly looked at the track record of the restorations. Sure, I could conserve tooth structure, but would the restorations last? The studies I read all stated that CEREC restorations performed at least as well as traditional restorative methods, if not better in many cases.

So what have I found in my practice? Since Feb. 10, 2004, I have cemented 1,276 CEREC restorations. How many have failed? Thirteen. The majority failed because of “operator error,” meaning I under-prepared the tooth for the restoration and the decreased thickness resulted in a fracture of a portion of the restoration. All but one of these CERECs were replaced with a new CEREC restoration of greater thickness and all of these restorations are doing well today. The one patient who didn’t opt for a new CEREC restoration asked for gold instead.

Overall, I would say a 1% failure rate is doing pretty well. Additionally, I have noticed over these five years, it is truly a rare occasion that any patient has post-operative sensitivity subsequent to having a CEREC restoration placed. I suspect there could be many reasons for this, but one of the most obvious is they aren’t wearing some “temporary” restoration for 2-3 weeks that leaks and allows bacteria to invade the dentinal tubules during that time. One of the biggest benefits to single-visit CAD/CAM dentistry is the patient walks out with a final restoration rather than having to wear a temporary until the case returns from the lab. In terms of sensitivity, I suspect it also is helpful that because we are saving so much tooth structure creating more conservative restorations, the nerve complex inside the tooth is less irritated than when all the enamel is ground away for a full-coverage crown. Don’t get me wrong, I still do full-coverage crowns, but it is more the exception than the rule. In this case, the patient presented with old amalgam restorations in need of repair (Figs. 4 and 6). The case was completed chairside with CEREC, and 3.5 years later the restorations are going strong (Figs. 3 and 5).

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