The T Scan II Occlusal Analysis System (Tekscan, inc. Boston, MA) is a clinical adjunct that precisely measures occlusal contact timing sequences in real time, as well as, the occlusal forces contained within the sequenced occlusal contacts. It is a Microsoft Windows (Microsoft Corp. Tukwila, WA) compliant diagnostic computer workstation that requires an IBM compatible PC with a Pentium processor, and 4-8 megabytes of RAM, to properly operate the system. The graphical interface uses WindowsR toolbar icons to display the software features that are utilized to analyze occlusal contact information1,2 (Fig. 1).
The T-Scan II records and measures tooth contact force and timing data in real-time by embedding 1370 .05 in2 pressure measurers (known as “sensels”) into a dental arch-shaped recording sensor (Figs. 2 & 3). Each sensel is scanned for occlusal contacts 100 times per second. The recorded data is imported into the T-Scan II software and hardware by a handle that holds the sensor in place intraorally. The software and hardware combine to measure the order, duration, and force content, of the recorded occlusal contacts. The occlusal data is then displayed graphically for analysis in 2 or 3 dimensions as a dynamic movie that can be played forwards or backwards incrementally3 (Fig. 4).
.01 second real-time recording of an occlusal contact event (Closing into MIP or CR, mandibular excursions, multiple clenches, any combination of these) is accomplished with the highly repeatable, High Definition Sensor.3 The .01 second incremental playback of the recorded contact sequence, illustrates the exact order of tooth contacts, as well as their force content. The combination of contact order, contact duration, contact location, and contact force content, all determine the degree of contact simultaneity, and the force balance that is present or absent in a particular occlusal scheme.4
Clinical applications of the T Scan II system are numerous.1,2,4-10 Occlusal adjustment procedures performed upon on differing dental prostheses, implants, or natural teeth, can be guided by computer analysis where the operator can predictably accomplish precision ideal measurable occlusal endpoints.1,2,4-10
How does the T-Scan II help the Dentist reach these ideal endpoints? The reason is: the T-Scan II measures the forces and timing in the Articulating Paper marks (whereas Articulating Paper can not) so the operator has knowledge of what the paper marks mean.
Contact Labeling with articulating paper/ribbon marks is believed to illustrate the nature of the timing and occlusal force that is contained within the labeling. The depth of color, and the surface area of the occlusal marking, is perceived by the operator to describe the contact force.
However, articulating paper marking materials have many use limitations. Studies by Schelb et al,11 Halperin et al,12 and Mori et al13 describe paper thickness, marking ability and material types. But there are no studies in the dental literature that suggest articulating paper can measure occlusal contact time or force data. In short “Paper is just Paper” and paper is not capable of measuring force and time.
As evidence for the lack of correlation between paper mark appearance and true force content, In a recent masters’ thesis at the University of Iowa department of prosthodontics, it was found that an experienced operator adjusting 40 maxillary casts with a known right to left force imbalance, worsened 12 out of the 40 casts (30% of the casts) with a range of 1-8% worse by using paper and shim stock only. When the same operator used the T Scan II system on the 40 casts, only one cast (2.5% of the casts) was worsened by .5%.14
By viewing the force and time data, and correlating it to the locations (only) of articulating paper marks, the sequence of contacts and the forces contained within each labeling can be visualized, and interpreted. Then, corrective occlusal adjustments made to natural teeth, dental prostheses and implant prostheses, can be made with knowledge of the order and force content within a specific (or a series) of marks. Occlusal force control on dental materials, dental implants, and/or natural teeth can then be measurably designed to insure material, implant, or occlusal surface survival.
Bilateral contact simultaneity4 can be clinically established through measurement of the occlusal contact sequence. This insures no one region of the dental arch contacts too early (forced to absorb excess early stress) or too late (unable to assist the other regions in force dissipation). Both precision force and time control is afforded the operator through measurement with the recording sensor which replaces the “hit or miss” operator subjective interpretation of colored ink marks on teeth. Figure 5 shows the “before” and “after” T Scan II recordings of the same maxillary 14 unit PFM prosthesis. The left plot shows the excessive force and early right sided nature of the paper only result, which is very non simultaneous. By refining that force pattern with the T Scan II, the end result on the right side illustrates near perfect force balance. The after plot shows a bilaterally simultaneous occlusal design.
This same principle can be applied to any clinical situation from occlusal diagnosis to delivering a dental prostheses. It is possible to make measured assessments followed by measured occlusal force and timing adjustments to any prosthesis or natural teeth to improve patient prosthesis acceptance, and reduce MPDS symptoms9,10 and occlusal discomfort. Precision occlusal endpoints, where all teeth meet in .2 seconds or less,4 all posterior teeth disclude in .4 seconds or less from excursive commencement,5 and 50% right side -50% left side force balance,4 is readily attainable when corrections are guided by the T-Scan II system.
In summary, the dentist can benefit during dental procedures by employing T-Scan II analyses followed by measured corrective occlusal adjustments in differing occlusal scenarios:
1. Finding occlusally activated painful teeth;
2. Controlling occlusal forces on glass ceramic or all-porcelain restorations;
3. Stabilizing complete dentures by centering the occlusal force summation into the exact middle of the maxillary denture;
4. Fixed prosthesis insertion force control;
5. Removable prosthesis force control;
6. Minimizing forces that result in abfractions;
7. Controlling damaging protrusive forces on porcelain veneers;
8. Establish true and measurable 50% right side to 50% left side balance on TMD splints to insure that both TM Joints are being loaded equally;
9. When implants and teeth reside in the same arch, delaying implant occlusal contacts, so they receive minimal occlusal force (but are in contact) until after the nearby natural teeth occlude and move within the PDL fibers;
10. With complete arch implant prostheses, centering occlusal forces within the central distribution of implants to insure axial loading reducing “shear stress” to implants;
11. Developing measurable immediate posterior disclusion with complete anterior guidance control on natural teeth, or dental prostheses, so that less muscle fibers are recruited during excursive function. This ‘unloads” the occlusion from excess muscle activity during function;
12. Improving natural tooth occlusal adjustment procedures like Disclusion Time Reduction5,6,9,10 and Occlusal Equilibration.15
13. Diagnosing Occlusal problems without mounted diagnostic casts– the rapid data acquisition and playback of a given recording affords the operator instantaneous recall of a patients’ force and time aberrations that can not be detected by mounting diagnostic casts.
A significant advantage of using the T Scan II system is that it provides measurable force and time information that insures the operator can properly complete any occlusal adjustment procedure by reaching known numerical occlusal endpoints. These endpoints require computer assessment and cannot be visually, a
udibly, paper labeling, or patient confirmed. When performing occlusal adjustments with paper only, in the absence of measurement, the operator cannot be cognizant of whether ideal occlusal endpoints have actually been obtained. Therefore, he/she can not be sure that the occlusion is accurately adjusted and whether or not they have completed the procedure. The clinical reality that unmeasured occlusal adjustments may not result in ideal endpoints may be partially responsible for the lack of survival of some dental prostheses, as well as clinical scenarios where the patient cannot accept the delivered occlusal design.
Dr. Kerstein is a clinical consultant for Tekscan, Inc. However, he will receive no compensation from the sales of any Tekscan product.
Dr. Kerstein graduated from Tufts University School of Dental Medicine DMD, 1983, Certificate in Prosthodontics 1985, Assistant Clinical Professor.
Oral Health welcomes this original article.
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