Analyzing Muscle Function During Mastication

1. Analyzing Muscle Function During Mastication BioResearch Associates, Inc. John C. Radke

2. 3 Patterns of Mastication(These “Categories” are Parts of a Continuum) • Normal Movement Pattern + Normal Muscle Activity = Ideal Function • Normal Movement Pattern + Abnormal Muscle Activity = Effective Adaptation • Abnormal Movement Pattern + Abnormal Muscle Activity = Difficult/Poor Adaptation

3. Normal Masticatory Movements Bilateral ACP (29 normals*) • All Convex • Turning Point Working Side • Clockwise (frontal and horizontal) • All Within 2 SD (no fat lines) * Matches 500 normals from Maruyama in Japan

4. Normal Masticatory Movements Bilateral Horizontal ACP (29 normals*) • All Convex, Clockwise (frontal and horizontal) • Turning Point Working Side, All Within 2 SD • Affected most by “Yaw” in the mastication pattern * Matches 500 normals from Maruyama in Japan

5. Normal Masticatory Movements Left Vs Right Velocity ACP (29 normals) Closing a little faster and more variable

6. Normal Masticatory Movements Sagittal ACP (29 normals) Some separation between opening and closing • Angle of closure varies a lot • Least diagnostic view of mastication

7. Normal Masticatory Movements Right Side ACP • All Convex (Frontal & Hor.) • Turning Point Working Side • Clockwise (frontal and horizontal - R) • All Within 2 SD (no fat lines) • Closing Velocity > Opening • Straight Closing in Sagittal

8. Abnormal Masticatory Movements Right Side ACP • Not Convex • Turning Point on Midline • Counterclock-wise (frontal and horiz.) “Reversed Sequence” • All of closing is fat lines! > 2 SD • ClosingVel. < OpeningVel. • Sagittal closing deviation

9. Raw Frontal Mastication Frontal View • Consistency -Randomness • Asymmetrical Shape – all over the place • Clearly left sided or not Note: Even the RAW frontal movement pattern conveys a sense of much greater variability in the abnormal chewing pattern. Normal variation is more organized.

10. Raw Horizontal Mastication • Abnormal Chewing Gum • Inconsistency – Random • Angular lines w- corners • Normal Chewing Gum • Consistency w-Variability • Smooth lines w/o corners

11. Raw Masticatory Velocity Fast, SmoothCycles Closing > Opening Slow,EraticClosing (faster, but still relatively slow open) Note: Abnormal opening can be relatively smooth, but closing … not so much!

12. Comparing Normal Subjects to some with TMJ Internal Derangements

13. The Quality of Chewing is Continuous, not Dichotomous! • You can recognize Good Function, • When function is compromised, you can improve it • Well adapted patients don’t realize how bad their function is until you improve it • Poorly adapted patients can struggle with what would otherwise be only minor impediments to good function • Improving masticatory function can have global effects

14. What about Muscle Function? TEMPORALIS • 16 normals • Chewing Gum • Working Ta Vs non-working Ta • The amplitudes of the contractions are only significantly different above 25 – 50 % of the maximum level • Max difference = 40%

15. What about Muscle Function? MASSETER • 16 normals • Chewing Gum • Working Mm Vs non-working Mm • The amplitudes of the contractions are significantly different above 20 – 30 % of the maximum level • Max difference = 140%

16. What about Muscle Function? Note: Graph colors yellow and cyan, the muscle levels are significantly different

17. Mastication Sweep(Asymptomatic “Normal” Subject – right side) Initial Recording of Chewing Gum – Right Side Note: The even, consistently uniform pattern

18. Mastication Sweep - Zoom(Asymptomatic Subject – right side) Note the consistency again

19. Mastication Sweep & ACP(Asymptomatic Subject – right side – 15 cycles) See how closely the ACP matches normal

20. EMG RMS Sweep(Asymptomatic Subject – right side – same 15 cycles) Zoom View of Cycle 2

21. Mastication Sweep & ACC(Asymptomatic Subject – right side – same 15 cycles)

22. Average Chewing Cycle(Normal Pattern – Right Side – 15 cycles)

23. Average Chewing Cycle(Normal Pattern – Left Side – 15 cycles)

24. Average Chewing Cycle(Normal Patterns – Left & Right Sides – 15 cycles) Note: The pattern for left mastication is the inverse of right mastication pattern.

25. Non-normal Chewing Cycle(Abnormal Subject – Left Side – 11 cycles) Left Side Chewing F2 ACP = R-DDR Note: R-DDR = Right Displaced Disk with Reduction

26. Non-normal Chewing Cycle(Abnormal Subject – Left Side – same 11 cycles) Left Side Chewing F2 ACP R-DDR Weak Muscle Function Note: There is very weak muscle activity shown in the Zoomed View

27. Non-normal Chewing Cycle(Abnormal Subject – Left Side – same 11 cycles) Left Side Chewing F2 ACP R-DDR Weak Muscle Function Weak ACC Note: The Average Chewing Cycle (ACC) muscle pattern is temporalis dominant and weak overall. This is evidence of an accommodative dysfunction in centric.

28. Appliance - Chewing Cycle(More normal result – Left Side – 12 cycles) Left Side Chewing No F2 ACP Note: This is the same patient with a full coverage lower appliance. Occlusal morphology is lacking, but right TM Joint function is improved.

29. Appliance - Chewing Cycle(More normal result – Left Side – 12 cycles) Left Side Chewing No F2 ACP Strong Muscle Function Note: Minutes later, three times stronger function. Activity is less temporalis dominant, but working masseter function is not completely restored yet.

30. Appliance - Chewing Cycle(More normal result – Left Side – 12 cycles) Left Side No F2 ACP Strong Muscle Function Strong ACC Note: Nearly normal activity distribution on the appliance. Working (left) masseter and temporalis levels are approximately reversed. Non-working temporalis is low.

31. ACC Without Vs With Appliance (More normal result – Left Side – 12 cycles) Dramatic improvement in muscle function with the addition of an occlusal appliance Note: Intercuspal Chewing Left side Chewing on appliance (1 minute later)

32. ACP Without Vs With Appliance (More normal result – Left Side – 12 cycles) Dramatic improvement in the Consistency Note: Quantitative differences between chewing in ICP and on an Appliance

33. X-Y Without Vs With Appliance (More normal result – Left Side – 12 cycles) Note: Changes in the movement pattern are not as dramatic as changes in muscle function

34. ACC Without Vs With Appliance (More normal result – Left Side – 12 cycles) Dramatic improvement in the strength of the ACC pattern with an occlusal appliance Increase (100%) no difference decrease increase (300%) increase no change increase no change Working Mm and Ta closer Not perfect but better

35. ACC Without Vs With Appliance (More normal result – Left Side – 12 cycles) Dramatic improvement in the strength of the ACC pattern with an occlusal appliance

36. ACC Normal Vs With Appliance (More normal result – Left Side – 12 cycles) Normal ACC pattern Vs occlusal appliance (This could be a “sufficient” result, but room exists for improvement) Improved, but not perfect!