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

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Figure 8 Left horizontal MI/CR discrepancy. Figure 9 Left vertical MI/CR discrepancy. Figure 10 Transverse MI/CR discrepancy. Discussion Results of the present study indicate a statistically significant improvement in MI-CR discrepancy in the right horizontal, right vertical, left vertical, and transverse planes with 2 months of gnathologic positioner wear. The condylar axis distraction differences in the left horizontal planes were not statistically significantly different. Before positioner wear, the mean right horizontal, right vertical, left vertical, and transverse measurements were 1.306 mm, 1.217 mm, 1.162 mm, and 1.031 mm respectively, and fell outside the ± 1.0 mm vertical and horizontal as well as the ± 0.5 mm transverse distraction envelope proposed by Crawford, Utt et al, and Slavicek. 12,13,14 Following 2 months of positioner wear, the amount of condylar distraction in these 4 measurements showed statistically significant improvement and came within the distraction envelope. Before positioner wear, 3 patients (11.5%) had MI-CR discrepancy that fell within the envelope of susceptibility in all 5 of the measurements examined, while 11 patients had all 5 measurements within the envelope after positioner wear (42.3%). Reducing MI- CR discrepancies is an important treatment goal in the gnathological philosophy, and the use of gnathologic positioner is essential to achieving this goal. Although these changes were nonsignificant when compared to change in the control group, the level of significance in the right horizontal, right vertical, and left vertical planes was very close to the significance level of 0.01 used for this study, and below the more common 0.05 level of significance. Figures 6, 7 and 9 show a similar pattern with reduction in MI-CR discrepancy over time with positioner wear, while the group with the Hawley retainers shows an increase in MI-CR discrepancy. This trend is observed in 3 of the 5 measurements studied (right horizontal, right vertical, and left vertical planes). The positioner and control groups tend to change differently over time in the vertical and horizontal planes, with the positioner group improving and the control group getting worse. This is consistent with Roth’s claim that general retention protocols with Hawley-type appliances following orthodontic therapy will tend to make MI-CR discrepancy worse, while gnathologic positioners will improve MI-CR discrepancy. Interestingly enough, all mean vertical and horizontal CPI measurements for the control group started within the distraction envelope of ± 1.0 mm and finished outside the envelope following 2 months of Hawley retainer wear. The small sample size of the control group is a limitation of this study. A larger sample size would eliminate type II error and might show a statistically significant difference in the change in MI-CR discrepancy over time between the control and the positioner group. However, the p-values are below 80 Chiang, Freeland, et al | Effect of Gnathologic Positioner Wear on Maximum Intercuspation CR Disharmony
the .05 level of significance in the right horizontal, right vertical, and left vertical planes. Furthermore, the MI-CR pattern is observed, suggesting that this is not a purely random phenomenon. Since the control group was small, there is the possibility of an underpowered study. In the transverse plane, there appears to be no difference between the 2 groups over time. A condylar axis distraction in the transverse plane is more sensitive to clinical problems than a condylar axis distraction in the horizontal and vertical planes. 17,18,19 It appears that gnathologic positioners improve the result of orthodontic treatment with respect to condylar axis distraction. Conclusion Results of the present study indicate a statistically significant improvement in MI-CR discrepancy in the right horizontal, right vertical, left vertical, and transverse planes with 2 months of gnathologic positioner wear. The amount of condylar distraction in these 4 measurements showed statistically significant improvement and came within the envelope of susceptibility. The positioner and control groups tend to change differently over time in the vertical and horizontal planes, with the positioner group improving and the control group getting worse. In the transverse plane, gnathologic positioners improve the result of orthodontic treatment with respect to condylar axis distraction. ■ References 1. Okeson JP. Management of Temporomandibular Disorders and Occlusion. 3rd ed. St Louis, MO: Mosby; 1998:109-125. 2. Schmitt ME, Kulbersh R, Freeland T, et al. Reproducibility of the Roth power centric in determining centric relation. Semin in Orthod. 2003;9(2):102-108. 3. Andrews LF. The six keys to normal occlusion. Am J Orthod. 1972;(62):196-309. 4. Stuart CE. Good occlusion for natural teeth. J Prosthet Dent. 1964;(14):716-724. 5. Roth RH. Temporomandibular pain dysfunction and occlusal relationships. Angle Orthod. 1973;(43):136-153. 6. Roth RH. Treatment mechanics for the straight wire appliance. In: Graber TM, Swain BH, eds. Orthodontics: Current Principles and Techniques. St Louis, MO: Mosby; 1985:665-716. 7. Roth RH. Occlusion and condylar position. Am J Orthod Dentofac Orthop. 1995;(107):315-318. 8. Pangrazio-Kulbersh V, Poggio V, Kulbersh R, et al. Condylar distraction effects of two-phase functional appliance/edgewise therapy versus one-phase Gnathologically based edgewise therapy. Semin in Orthod. 2003;9(2):128-139. 9. Roth, RH. The maintenance system and occlusal dynamics. Dent Clin North AM 1976;20:761-788 10. Arnett GW, Milam SB, Gottesman L. Progressive mandibular retrusion-idiopathic condylar resorption, part II. Am J Orthod. 1996;(110):117-127. 11. Roth RH. Functional occlusion for the orthodontist, part I. J Clin Orthod. 1981;(15):32-51. 12. Crawford SD. Condylar axis position, as determined by the occlusion and measured by the CPI instrument, and signs and symptoms of temporomandibular dysfunction. Angle Orthod. 1999;(69):103-116. 13. Utt TW, Meyers CE Jr, Wierzba TF, Hondrum SO. A three-dimensional comparison of condylar position changes between centric relation and centric occlusion using the mandibular position indicator. Am J Orthod Dentofac Orthop. 1995;(107):298-308. 14. Slavicek R. Interviews on clinical and instrumental functional analysis for diagnosis and treatment planning, part I. J Clin Orthod. 1988;(22):358-370. 15. Lavine D, Kulbersh R, Bonner P, Pink FE. Reproducibility of the condylar position indicator. Semin in Orthod. 2003;9(2):96-101. 16. Klar NA, Kulbersh R, Freeland T, et al. Maximum intercuspationcentric relation disharmony in 200 consecutively finished cases in a gnathologically oriented practice. Semin in Orthod. 2003;9(2):109- 116. 17. Kulbersh R, Dhutia M, Navarro M, et al. Condylar distraction effects of standard edgewise therapy versus gnathologically based edgewise therapy. Semin in Orthod. 2003;9(2):117-127. 18. Freeland T, Kulbersh R. Orthodontic therapy using the Roth gnathologic approach. Semin in Orthod. 2003;9(2):140-152. 19. Roth RH, Rolfs DA. Functional occlusion for the orthodontist, part II. J Clin Orthod. 1981;(15):100-123. RWISO Journal | September 2010 81
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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
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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
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Hinge Axis: The Need for Accuracy i
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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 and 70: Physiologic Treatment Goals in Orth
Page 71 and 72: REFERENCES 1. Dawson PE. The Concep
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: For these analyses, the desired sig
Page 83 and 84: RWISO Journal | September 2010 83
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