Modern-day occlusal analysis

by Paul Feurestein

At Tufts University School of Dental Medicine, Dr. Kerstein has conducted clinical research regarding the roles that occlusion and lengthy disclusion time play in the etiology of Chronic Myofascial Pain Dysfunction Syndrome. His work with the T-Scan II Occlusal Analyzer has led to his becoming a leading author and researcher in computerized occlusal analysis.

DE: Dr. Kerstein, thank you for allowing us to explore modern-day occlusal analysis with you. We at DE are very interested in how computers are influencing dentistry in general, but in your specific case, how they are improving the clinical science and treatment of occlusal problems. From what I understand, you have been a pioneer, of sorts, in computerized occlusal analysis.

Dr. Kerstein: Yes that's true. Around 1984, I began looking at occlusal contact information through the eyes of the original T-Scan I computer. It was developed by one of my prosthodontic residency faculty, Dr. William Maness, in 1983. It was the precursor to today's T-Scan II Occlusal Analysis System.

DE: Back then, were computers helpful in diagnosing occlusal problems?

Dr. Kerstein: Absolutely. The T-Scan I took a great deal of guesswork out of discerning forceful occlusal contacts and understanding contact time variances and aberrances. But its sensor was not sensitive enough to precisely grade occlusal forces in small differing force levels, and the entire system was not really well understood for predictable clinical use. No one had figured it out, so the user was on his own to try to determine what to do with the recorded data.

DE: So how did you learn to apply the information if there was minimal understanding of what it was showing you?

Dr. Kerstein: I observed the T-Scan I findings and tried to correlate them with the concepts of occlusion that were being advocated in the early 1980s. Also, I observed the articulator paper markings that represented the occlusal contact patterns. I adjusted the occlusion based upon where the T-Scan I data illustrated which paper marks were too forceful and time premature.

I realized soon after implementing computerized occlusal analysis to guide my occlusal adjustments, that to achieve ideal occlusal endpoints was not possible by attempting to interpret patient feel and paper markings. The T-Scan I described force and time abberations within an occlusal scheme even when the paper marks appeared uniform throughout the arch and the patient reported that his occlusion felt good. A great deal of occlusal contact detail regarding force and timing was clearly being missed between what the patient reported and what articulating paper illustrated.

All of that is still true today and more precisely described with the T-Scan II system and its high-definition recording sensors. Very often, the patient cannot accurately quantify his occlusal perceptions. In my experience, the most forceful contacts in the occlusion are not "felt" by the patient unless they are grossly forceful. Patient perception is imprecise, and when an operator uses it to guide occlusal adjustments, they are often spending valuable chair time just chasing paper marks around the arch.

What is unique about T-Scan technology, both then and now, is that the recorded occlusal contact information is actually a dynamic movie of changing forces that describe transitions of occlusal contacts that occur over the passage of time. These Force Movies quantify in precise detail which contacts are too forceful, too early, and on which teeth are they concentrated. This eliminates the need for the operator to use patient perception as a very poor guide to occlusal adjustment procedures. In comparison to articulating paper markings, which only reveal the endpoint stamp of the occlusal contact sequence, T-Scan Force Movies reveal the intricacies of the order of contacts in .01 second increments, so that the operator can see the occlusal changes that occur in fleeting moments that the eye misses and the paper markings cannot describe. These fleeting moments often can reveal time problematic contacts and contact force concentrations that create patient discomfort with a given occlusal scheme.

The dynamic nature of these recordings allowed me to discover occlusal parameters like Disclusion Time and Occlusion Time4 that were never reported upon in the literature or seen because we humans cannot visualize .01 seconds of transitory occlusal contact information.

DE: So, jump forward to today. How does computerized occlusal analysis help you in your daily practice?

Dr. Kerstein: Probably the single most beneficial use of T-Scan II technology is in case finishing dental prostheses so that they are measurably time simultaneous and force-balanced at the prosthetic delivery visit. T-Scan technology has virtually eliminated the unpleasant follow-up visits many dentists persevere through when a patient can't wear the occlusion given to him at delivery.

When properly employed — and I emphasize "properly" — case finishing with The T-Scan II ensures that despite what the patient describes about his prosthetic occlusion, and despite what articulating paper appears to show, the operator knows: a) the degree of occlusal force balance; b) the precision of the occlusal contact time simultaneity; and c) the length of time required to disclude the posterior teeth.

DE: How does that help the practicing dentist?

Dr. Kerstein: It will save them time after insertion by eliminating unwanted and costly post-insertion, patient adaptation occlusal-adjustment visits.

DE: So having a T-Scan II reduces the possibility of missing the occlusion at delivery?

Dr. Kerstein: In my practice — almost every week — I receive new patients sent to me from other dentists to correct their installed occlusion. Usually, the patient has gone back to his dentist four to five times post-insertion for a few months or so to get the occlusion comfortable. Finally, they both give up and I receive the case. With T-Scan II analysis, the problem contacts can be quickly isolated and then refined with adjustment. The final patient statement is very telling: "Why doesn't my dentist have one of these computers?"

DE: Where else do you find application for computerized occlusal analysis?

Dr. Kerstein: There are numerous clinical applications. Here are the most common uses:

• Understanding paper markings.
• Natural tooth occlusal adjustments for TMD.
• Splint balancing.
• Adhesive restorative case finishing.
• Dental implants.

The T-Scan II affords the operator quantifiable force data that cannot be obtained with articulating paper.

DE: So preservation of the implant and or bone interface and prosthesis integrity are optimized with T-Scan II-guided corrections?

Dr. Kerstein: The force data guides the corrective adjustments to measurable precision force and time balance, therefore eliminating patient subjectivity and articulating paper guesswork. The operator then ensures that his or her prosthesis has a much greater chance of long-term survival. No other tool can give the operator this kind of prosthesis force control.

DE: Any other applications that you haven't touched upon?

Dr. Kerstein: Another beneficial use of the T-Scan II is finding the problem contact that causes a tooth to be painful under occlusal loading.

Often, dentists chase paper marks while trying to isolate which tooth and which contact is the painful one. They waste a great deal of time and randomly grind paper marks. It's like throwing darts at the problem area. Often, many visits are required to find the problem contact, and a great deal of time is wasted trying to isolate the contact that stimulates the pain.

With computer analysis, the high-impact contact is quickly isolated, adjusted, and then the pain under loading goes down rapidly. With computer analysis, this procedure becomes predictable, rapid, and effective.