SmartPrep™ Conserves Healthy Tooth Structure and Reduces Need for Anesthesia By: Marshall White, DMD

In treating a tooth affected by the disease of caries, dentists have long understood that the removal of the affected part of that tooth can either forestall or arrest the progression of the caries process. For nearly as long we’ve known that inadequate removal of the carious tooth structure will not cause the progress of decay to cease, and that (often despite even proper restoration…) tooth decay will progress unchecked into the affected tooth. In his 1778 treatise entitled The Natural History of the Human Teeth, one early expert who held the title “Physician Extraordinary to the KING”, Englishman Dr. John Hunter wrote about tooth decay, “The first thing to be considered, is, the cure of the decaying state of the Tooth, or rather the means of preventing the further progress of the decay; and more especially before it hath reached the cavity [pulp chamber], whereby the tooth may be in some degree preserved…I have known cases, where the black spot having been filed off, and scooped entirely out, the decay has stopped for many years. This practice is supposed to prevent at least any effect, that the parts already rotten may have upon the sounder parts…”

Traditionally, trained modern dentists’ clinical discernment of carious tooth structure has been based upon the appearance of that tooth structure and the degree to which it can be pierced by a sharply pointed explorer. In the last two decades we have also enjoyed the more widespread use of the aid afforded by caries disclosing dyes. Particularly as the science of cariology has progressed, the objective precision of these former methods has been examined and, in the eyes of some, found wanting with regard to their ability to permit removal of only carious dentin. Especially in today’s era of Minimally Invasive Dentistry, many dentists are often interested in preserving as much healthy tooth structure as possible when excavating a carious lesion, myself included. But how do we determine exactly how far to go with our instrumentation and not remove healthy dentin unnecessarily?

Enter SmartPrep™ instruments from SS White®
Some very knowledgeable dentists and the developers at SS White asked themselves this very question. They embraced the reality that carious dentin is softer than sound dentin, and set about the task of developing a rotary instrument that would facilitate excavation of carious dentin without removing sound dentin adjacent to the carious lesion. The end result of that journey has been the recent introduction of the SmartPrep instrument, a polymer rotary instrument designed to cease cutting when it has removed carious dentin and reaches healthy tooth structure. I was asked to participate in beta-testing and have had the opportunity to use this instrument for several months. Here is my personal evaluation of this new product.

While there is a learning curve involved, it is not steep. Once mastered, I found the instrument to be very doctor- and patient-friendly. One needs to envision the outline form of the final preparation and remove the necessary enamel, old restoratives and dentin to expose the dentinal lesion using conventional methods. Used without water at 500-800 rpm in a conventional latch-type slow-speed handpiece, the SmartPrep instrument is first used in the softest, most demineralized area of the lesion. Working outward from there, the rest of the lesion is excavated concentrically until the instrument essentially wears out. The flutes of the instrument will become blunted as they encounter sound dentin. I quickly learned to discern this so as not to unnecessarily subject the tooth to frictional heat once it stops decay removal.

An interesting side-benefit to this instrument, and one that will appeal to dentists who benefit from internal marketing, is the fact that the majority of properly chosen cases can be completed without anesthesia. It has been hypothesized that much of the stimulatory effect of dental instrumentation is due to disturbing or cutting vital odontoblastic processes within dentinal tubuli. The tubuli of carious dentin is absent vital odontoblastic processes because of the pulp’s natural response to advancing decay. Because the SmartPrep instrument does not cut beyond the zone of carious dentin and, (used properly at slow revolutions per minute) doesn’t generate heat, it has little or no stimulatory effect upon the pulp. While I quickly discovered such slow rpm instrumentation with this rotary instrument caused both me and my patients to experience some slight vibration, most patients don’t find this alarming. As a clinician I have found that I’ve developed a “feel” for its use: that changes in this vibratory sensation aids me as a form of positive feedback to allow me to know how it is working and when I am done.

Application

I have always been a fan of SS White burs, and if I use Fissurotomy and GW-1 carbides on my high-speeds for careful entry to the tooth and removal of old restoratives, there is little sensation and no discomfort. Similarly, I frequently use diamonds when addressing enamel and with a soft touch have little problem with initial access using these. Then followed by use of the SmartPrep for removal of carious dentin, there still is no appreciable pain in most patients. I have even excavated a number of deep lesions in patients without anesthesia and without a mid-treatment request for local. Naturally, I do not attempt this with the dentophobic or even a patient who has a history of poor reaction to the dental experience. Instead I will choose cases for this from patients who are well acclimated and stoic to having dental work; or from those who voice a great aversion to being numb afterwards and respond positively to my offer to try something new. We always make sure the patient is aware that at any time they can request local anesthetic.

SS White reports that in a survey conducted with dentists using SmartPrep for 224 cavity preparations, 79.9% (179) of them were begun with no anesthesia.

As mentioned earlier, there is a learning curve. Initially, I was too aggressive and went through more than a single bur per tooth because I chose the wrong size or failed to apply the principle of starting in the softest area of dentin and working outward concentrically. Now more experienced, I rarely need to use more than a single SmartPrep instrument.

In my view, there are two scenarios where the SmartPrep especially shines. First, when treating the asymptomatic tooth with radiographically obvious deep decay approaching the pulp. This is the kind of tooth where I’d either advise the patient that s/he would need RCT, or upon which I’d attempt a modified prep for caries-arrestment much like an indirect pulp cap sealed with bonded composite. Generally I will numb them, and more for my own peace of mind than because I think it will hurt. (I have done a few really deep ones without anesthetic, and only one wanted LA before completion.) In these cases, I’ve had no pulp exposures, ended up bonded to sound tooth structure with a hard feel to a sharp 3ES explorer, and no post op pain. Granted, it’s only been a few months, but so far so good.

Secondly, I have come to love the SmartPrep instrument when I want to impress non-phobic patients with small to medium decay who are hoping to avoid anesthetic. I give them some brief discussion about what it is and how it works, and tell them they’ll need to be willing to put up with some water and air and vibration. I go on to explain that it may be a bit like drinking cold iced tea. Almost all of these patients enjoy the fact they’re getting in on a new advance. The vast majority of these patients complete the procedure without requesting anesthetic (33/34 to date). All said they’d do it again (interestingly, even the one who ended up wanting LA.) Personally, I’ve little doubt these patients will be great ambassadors for my practice.

Unfortunately, caries-affected dentin that is also sound often is discolored. When working in the cosmetic zone, this is a potential problem. I once made the attempt to leave such dentin under the remaining facial enamel of a central incisor where I was placing a DIFL Cl. IV composite and it showed through. I have learned that in such areas, and purely for cosmetic reasons, it is sometimes more prudent to remove this for optimal aesthetics. Fortunately, even in teeth that are being instrumented without anesthetic, discolored-but-sound dentin in such cosmetically obvious areas can be removed without pain and with little adverse consequence restoratively.

In summary, I’d say the SmartPrep instrument has numerous applications. Prime among them for dentists committed to minimally invasive dentistry, we can maximally conserve tooth structure when using bonded restorative techniques. If a dentist wants to embrace a methodology to please the significant number of patients who prefer to have restorative dentistry done without anesthetic, yet doesn’t want the expense and commitment implied by hard-tissue lasers or air-abrasion, this will prove a very attractive option.

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Marshall White, DMD, is a wet-gloved dentist. In 1995, after a decade of solo and associatship practice, he founded Optimal Dental Care, Ltd., focusing upon using the most conservative, long-lived and patient friendly techniques. An avid participant at DentalTown.com, Dr. White is a self-described ‘simple country dentist’ and a tireless advocate of scientifically-based clinical practice.

He resides on five acres of wooded bliss in rural Licking Country, OH, with his wife, Jennifer, and their three young sons. Dr. White welcomes any and all communication and may be reached at (740) 344-1200 or by email at drwhite@optimaldental.com.