2010 RWISO Journal - Roth Williams International Society of ...

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tionship between the teeth, the joints, and the neuromusculature. This information provides a physiologic treatment goal for the orthodontist, a summary of which can be made by analyzing the system in loaded and unloaded conditions. When loaded, eg, during a swallow, the condyles are fully seated upward and forward in the fossae, the elevating muscles are active, and the dentition is in full intercuspation. 41,55,62,63,65,66 When unloaded, the condyles remain in firm and constant contact with the disc and eminence, elevating muscles are inactive and positioning muscles (eg, lateral pterygoids) are active, posterior teeth are out of contact, and the anterior teeth play a major role in guiding mandibular movements. 67-75 Given a reliable perspective of optimal static and dynamic relationships between the teeth, joints, and neuromusculature, we can consider some additional principles regarding gnathic function. There are at least three reasons why the intercuspal position is important. First, the positions and the shapes of the teeth determine mandibular movements at and near the intercuspal position. 7,50,61,76-100 Second, when the mandible is brought to full intercuspation in a functionally healthy system, the powerful elevating muscles are active and the system is heavily loaded; the bulk of the resultant force is absorbed by posterior teeth. 32,50-52,101-103 Third, condylar position is determined by the dentition at intercuspation. 61,83,104-106 An additional important factor well supported in the literature is the clinical observation that the neuromusculature is exquisitely programmed to guide the mandible to the intercuspal position80,85-100,107 ; the intercuspal position is dominant over condylar position. 61,83,103,105,106,108-110 Thus, asking a patient to “bite down” provides no dependable information as to where the condyle is positioned. Moreover, efforts to identify the seated condylar position through clinical maneuvers such as manipulating the mandible are not reliable. 28,111-116 To quote the master clinician Dr. Thomas Basta, “Don’t believe what you see in the mouth.” 2 Thus the value of using interocclusal devices such as cotton rolls, anterior jigs, and splints to deprogram the neuromusculature. If we are to apply these physiologic principles to the practice of orthodontics, we need additional information besides that which we have traditionally used; for example, techniques that record the optimal or “seated” position of the condyle. Currently there are numerous such techniques employed in restorative dentistry. Many clinicians use a hard stop at the incisor midline to separate the posterior teeth, along with a soft posterior material that can be hardened thermally or chemically. When the patient bites against the hard anterior stop and the neuromusculature seats the condyles superioranteriorly, the posterior material is hardened, and the musculoskeletally stable position of the mandible is recorded (Figure 1). 70 Girardot | Physiologic Treatment Goals in Orthodontics Figure 1 The anterior stop is hard and flat; it separates the posterior teeth to create appropriate space for a recording medium. The patient is instructed to close firmly, which seats the condyles to the musculoskeletally stable position of the mandible. The information then must be transferred from the patient to a device that will allow study and treatment planning of the gnathic system in three dimensions. Currently, the articulator appears to be the best tool for this purpose, although computer-generated three-dimensional technology may replace the articulator in the near future. Casts mounted on an articulator provide invaluable physiological information for diagnosis and treatment planning. For example, numerous studies show that there is nearly always vertical distraction of the condyle when the patient closes to intercuspation. 33,113,117-122 It is all but impossible to record, analyze, and treatment plan this vertical discrepancy without the use of a device such as an articulator. Joint images are another tool that can serve orthodontists with regard to physiologic treatment. Tomograms, as first advocated by Ricketts, have provided an effective way to study the health of the temporomandibular joint and the position of the condyle in the fossa. 123-125 At present, cone beam CT is a more effective way to study the temporomandibular joint, as it provides a more-lucid, three-dimensional view of joint structures. 36 There are sound data to support the concept that optimal gnathic function can be defined and used as an evidence-based treatment goal. There is little doubt that this would also aid communication between orthodontists and other dental professionals. In addition, knowledge of gnathic physiology is of substantial value to orthodontists in that it helps them to recognize and avoid myriad problems that occur in everyday practice. ■
REFERENCES 1. Dawson PE. The Concept of Complete Dentistry. St. Petersburg, FL: Center for Advanced Dental Study; 1994. 2. Basta T. Lecture and Clinical Procedures. Burlingame, CA: Foundation for Advanced Education; 1975-2000. 3. Guichet NF. Occlusion – A Teaching Manual. 2nd ed. Anaheim, CA: Denar Corportion; 1977. 4. Lee RL. Esthetics and its relationship to function. In: Claude Rufenacht, ed. Fundamentals of Esthetics. Chicago, IL: Quintessence; 1990:145-148. 5. McHorris WH. Occlusion with particular emphasis on the functional and parafunctional role of anterior teeth. J Clin Orthod. 1979;(13):606-608. 6. McNeill C. Fundamental treatment goals. In: McNeill C, ed. Science and Practice of Occlusion. Chicago, IL: Quintessence;1997:306-322. 7. Okeson JP. Management of Temporomandibular Disorders and Occlusion.3rd ed. St. Louis, MO: Mosby;1993:103, 111-115. 8. Roth RN. The maintenance system and occlusal dynamics. Dent Clinics N Am. 1976;(20):761. 9. McCollum, Stuart CE. A Research Report. Ventura, CA: Chas. E. Stuart; 1955. 10. Spear FM. Fundamental occlusal therapy considerations. In: McNeil C, ed. Science and Practice of Occlusion. Chicago,IL: Quintessence;1997:421-434. 11. Lucia VO. A technique for recording centric relation. J Prosthet Dent. 1964;(14):492. 12. Williamson EH: Occlusal concepts in orthodontic diagnosis and treatment, part I: the seated condylar position.In Johnson LE, ed. New Vistas in Orthodontic. Philadelphia, PA: Lea and Bebiger; 1985: 11. 13. Shore NA. Temporomandibular Joint Dysfunction and Occlusal Equilibration. 2nd ed. Philadelphia, PA: JB Lippincott;1976:238-241. 14. Dyer EH. Dental articulation and occlusion. J Prosthet Dent. 1967;(17):238. 15. Celenza FV, Nasedkin JN. Occlusion: The State of the Art. Chicago, IL: Quintessence; 1987. 16. Hylander WL, Bays RA. Bone strain in the subcondylar region of the mandible in Macaca fascicularis and Macaca mulatta. Am J Phys Anthrop. 1978;(48):408. 17. Hylander WL, Bays RA. An in vivo strain-gauge analysis of the squamosal-dentary joint reaction force during mastication and incision in Macaca mulatta and Macaca fasicularis. Arch Oral Biol. 1979;(24):689. 18. Hylander WL. An experimental analysis of temporomandibular joint reaction force in macaques. Am J Phys Anthrop. 1979;(51):433. 19. Hylander WL. Functional anatomy. In: Sarnat BG, Laskin DM, eds. The Temporomandibular Joint. 3rd ed. Springfield, IL: Charles C Thomas; 1979:85-89. 20. Boyd RL, Gibbs CH, Mahan PE, Richmond AF, Laskin JL. Temporomandibular joint forces measured at the condyle of Macaca arctoides. Am J Orthod Dentofac Orthop. 1990;(97):472. 21. Hansson T, Oberg T, Carlsson GE, Kopp S. Thickness of the soft tissue layers and the articular disk in the temporomandibular joint. Acta Odont Scan. 1977;(5):77. 22. Moffett BC, Johnson L, McCabe J, Askew H. Articular remodeling in the adult human temporomandibular joint. Am J Anat. 1964;(115):119-142. 23. Okeson JP. Bell’s Orofacial Pains. 5th ed. Carol Stream, IL: Quintessence;. 1995:297. 24. Hatcher DC, McEvoy SP, Mah RT, Faulkner MG. Distribution of local and general stresses in the stomatognathic system, In: McNeill C, ed. Science and Practice of Occlusion. Chicago, IL: Quintessence;1997:259-270. 25. Lundeen HC. Centric relation records: the effect of muscle action. J Prosthet Dent. 1974; (31):244. 26. Ito T, Gibbs CH, Marguelles-Bonnet R, et al. Loading on the temporomandibular joints with five occlusal conditions. J Craino Funct Dysf. 1986;(56):478. 27. Williamson EH, Steinke RM, Morse PK, Swift TR. Centric relation: a comparison of muscle determined position and operator guidance. Angle Orthod. 1980;(77):133. 28. Williamson EH, Evans DL, Barton WA, Williams BH. The effect of bite plane use on terminal hinge axis location. Angle Orthod. 1977;(47):25-33. 29. Strohaver RA. A comparison of articulator mountings made with centric relation and myocentric position records. J Prosthet Dent. 1972;(28):379. 30. Yustin D. Treatment position of the condyle. Research findings presented at: 44th Annual Meeting of the American Equilibration Society; February 1, 1999; Chicago, IL. 31. Teo CS, Wise MD. Comparison of retruded axis articular mounting with and without applied muscular force. J Oral Rehab. 1986;(8):363. 32. Lundeen HC, Gibbs CH. Advances in Occlusion. Boston, MA: J Wright-PSG;1982:7-11. 33. Girardot RA. The nature of condylar displacement in patients with temporomandibular pain-dysfunction. Orthod Rev. 1987;(1):16. 34. Wood DP, Floreani KJ, Galil KA, Teteruck WR. The effect of incisal bite force on condylar seating. Angle Orthod. 1994;(64):53. 35. Radu M, Marandici M, Hottel T. The effect of clenching on condylar position: a vector analysis. J Prosthet Dent. 2004;(91):171-179. RWISO Journal | September 2010 71
Page 1 and 2:
Contents Volume 2, No. 1, September
Page 3 and 4:
Letter from the President Samuel B.
Page 5 and 6:
News from the Roth Williams Teachin
Page 7 and 8:
In addition, three 8-hour courses w
Page 9 and 10:
Drs. Edson Illipronti and Solange F
Page 11 and 12:
The Transverse Dimension: Diagnosis
Page 13 and 14:
Figure 4 Patient with gingival rece
Page 15 and 16:
idge determines the width of the ma
Page 17 and 18:
Figure 16 MPV of a cone-beam CT sca
Page 19 and 20: 8. Vanarsdall RL. Transverse dimens
Page 21 and 22: Hinge Axis: The Need for Accuracy i
Page 23 and 24: to the flag table (Figure 25). The
Page 25 and 26: The Axi-Path is designed so that th
Page 27 and 28: Figure 43 Nasion relator moves tran
Page 29 and 30: The distance between the preauricul
Page 31 and 32: Figure 63 Flag table. Figure 64 Fla
Page 33 and 34: Figure 72 Figure 73 Supposition: Th
Page 35 and 36: Figure 83 The distance between the
Page 37 and 38: Condylar Resorption, Matrix Metallo
Page 39 and 40: Figure 4-c The extracellular activi
Page 41 and 42: shows promise in curbing the bone l
Page 43 and 44: 29. Zardeneta G, Milam SB, Lee T, S
Page 45 and 46: Comparison of Maxillary Cast Positi
Page 47 and 48: points. They found that the mean di
Page 49 and 50: Figure 2-a, b True-hinge facebow. F
Page 51 and 52: to adjust for experimentwide error
Page 53 and 54: pending upon the direction in which
Page 55 and 56: 28. Goska JR, Christensen LV. Compa
Page 57 and 58: The Effect of Tooth Wear on Postort
Page 59 and 60: Figure 4 Slight attrition occurred
Page 61 and 62: improved, with retraction of the up
Page 63 and 64: Figure 9-e Left lateral intraoral p
Page 65 and 66: All available intraoral photographs
Page 67 and 68: Figure 21 Mandibular movement after
Page 69: Physiologic Treatment Goals in Orth
Page 73 and 74: 70. McNamara JA Jr. The independent
Page 75 and 76: Effect of Gnathologic Positioner We
Page 77 and 78: sure was first checked in the mount
Page 79 and 80: For these analyses, the desired sig
Page 81 and 82: the .05 level of significance in th
Page 83 and 84: RWISO Journal | September 2010 83
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