Letters to the Editor based on the results of other studies, had the sample size been larger, a statistically significant correlation would have been detected. The size of the masseter muscle as well as the magnitude of the maximal molar bite force have both been inversely correlated with the gonial angle (7, 8). We therefore put forward the use of the gonial angle as an indicative cephalometric measure of the masticatory muscle functional capacity.
References 1. Antonarakis, G.S. and Kiliaridis, S. (2015) Predictive value of masseter muscle thickness and bite force on Class II functional appliance treatment: a prospective controlled study. European Journal of Orthodontics, 37, 570–577. 2. Kiliaridis, S., Mills, C.M. and Antonarakis, G.S. (2010) Masseter muscle thickness as a predictive variable in treatment outcome of the twin-block appliance and masseteric thickness changes during treatment. Orthodontics and Craniofacial Research, 13, 203–213.
337 3. Antonarakis, G.S., Kjellberg, H. and Kiliaridis, S. (2012) Predictive value of molar bite force on Class II functional appliance treatment outcomes. European Journal of Orthodontics, 34, 244–249. 4. Yoon, S.S. and Chung, C.H. (2015) Comparison of craniofacial growth of untreated Class I and Class II girls from ages 9 to 18 years: a longitudinal study. American Journal of Orthodontics and Dentofacial Orthopedics, 147, 190–196. 5. Raadsheer, M.C., Van Eijden, T.M., Van Spronsen, P.H., Van Ginkel, F.C., Kiliaridis, S. and Prahl-Andersen, B. (1994) A comparison of human masseter muscle thickness measured by ultrasonography and magnetic resonance imaging. Archives of Oral Biology, 39, 1079–1084. 6. Weijs, W.A. and Hillen, B. (1985) Physiological cross-section of the human jaw muscles. Acta Anatomica, 121, 31–35. 7. Benington, P.C., Gardener, J.E. and Hunt, N.P. (1999) Masseter muscle volume measured using ultrasonography and its relationship with facial morphology. European Journal of Orthodontics, 21, 659–670. 8. Ingervall, B. and Minder, C. (1997) Correlation between maximum bite force and facial morphology in children. The Angle Orthodontist, 67, 415–422.
European Journal of Orthodontics, 2016, 337 doi:10.1093/ejo/cjw025 Advance Access publication 6 April 2016
Ideal parameter to assess efficacy of fixed functional appliance: angular or linear? Anjana Devi M.S., Bhadrinath Srinivasan and Sridevi Padmanabhan Department of Orthodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India Correspondence to: Anjana Devi, Department of Orthodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai 600116, Tamil Nadu, India. E-mail: [email protected]
Dear Sir, We read the article by Zymperdikas et al. (1) published in May 2015, with great interest as the efficacy of fixed functional appliances is debatable. It was a meticulously performed and well-structured systematic review. The study summarized the current evidence on the clinical effectiveness of the fixed functional appliances in Class II malocclusions. The authors have mentioned that angular measurements were considered as primary treatment outcomes. Yet linear measurements in relation to the changes in mandible have always been a part of studies analysing the efficacy of the functional appliances (e.g. Co-Gn, Co-Pog). Though the linear measurements are prone to magnification bias, we wonder if the difference in the linear measurements between the post- and pretreatment lateral cephalograms would have elucidated the skeletal effects of the fixed functional appliances. Moreover, angular measurements such as SNB and ANB are influenced by the rotational effects of the jaws relative to the cranial reference
planes (2). Can the effectiveness of the fixed functional appliance be based on these parameters? Effects of both rigid and flexible fixed functional appliances had been assessed in the nine articles reviewed. According to the authors, would the rigidity of the appliance bring about a difference in the treatment outcome?
References 1. Zymperdikas, V.F., Koretsi, V., Papageorgiou, S.N. and Papadopoulos, M.A. (2015) Treatment effects of fixed functional appliances in patients with Class II malocclusion: a systematic review and meta-analysis. European Journal of Orthodontics, http://dx.doi.org/10.1093/ejo/ cjv034. 2. Jacobson, A. (1975) The “Wits” appraisal of jaw disharmony. American Journal of Orthodontics, 67, 125–138.
References 1. Antonarakis, G.S. and Kiliaridis, S. (2015) Predictive value of masseter muscle thickness and bite force on Class II functional appliance treatment: a prospective controlled study. European Journal of Orthodontics, 37, 570–577. 2. Kiliaridis, S., Mills, C.M. and Antonarakis, G.S. (2010) Masseter muscle thickness as a predictive variable in treatment outcome of the twin-block appliance and masseteric thickness changes during treatment. Orthodontics and Craniofacial Research, 13, 203–213.
337 3. Antonarakis, G.S., Kjellberg, H. and Kiliaridis, S. (2012) Predictive value of molar bite force on Class II functional appliance treatment outcomes. European Journal of Orthodontics, 34, 244–249. 4. Yoon, S.S. and Chung, C.H. (2015) Comparison of craniofacial growth of untreated Class I and Class II girls from ages 9 to 18 years: a longitudinal study. American Journal of Orthodontics and Dentofacial Orthopedics, 147, 190–196. 5. Raadsheer, M.C., Van Eijden, T.M., Van Spronsen, P.H., Van Ginkel, F.C., Kiliaridis, S. and Prahl-Andersen, B. (1994) A comparison of human masseter muscle thickness measured by ultrasonography and magnetic resonance imaging. Archives of Oral Biology, 39, 1079–1084. 6. Weijs, W.A. and Hillen, B. (1985) Physiological cross-section of the human jaw muscles. Acta Anatomica, 121, 31–35. 7. Benington, P.C., Gardener, J.E. and Hunt, N.P. (1999) Masseter muscle volume measured using ultrasonography and its relationship with facial morphology. European Journal of Orthodontics, 21, 659–670. 8. Ingervall, B. and Minder, C. (1997) Correlation between maximum bite force and facial morphology in children. The Angle Orthodontist, 67, 415–422.
European Journal of Orthodontics, 2016, 337 doi:10.1093/ejo/cjw025 Advance Access publication 6 April 2016
Ideal parameter to assess efficacy of fixed functional appliance: angular or linear? Anjana Devi M.S., Bhadrinath Srinivasan and Sridevi Padmanabhan Department of Orthodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai, Tamil Nadu, India Correspondence to: Anjana Devi, Department of Orthodontics, Faculty of Dental Sciences, Sri Ramachandra University, Porur, Chennai 600116, Tamil Nadu, India. E-mail: [email protected]
Dear Sir, We read the article by Zymperdikas et al. (1) published in May 2015, with great interest as the efficacy of fixed functional appliances is debatable. It was a meticulously performed and well-structured systematic review. The study summarized the current evidence on the clinical effectiveness of the fixed functional appliances in Class II malocclusions. The authors have mentioned that angular measurements were considered as primary treatment outcomes. Yet linear measurements in relation to the changes in mandible have always been a part of studies analysing the efficacy of the functional appliances (e.g. Co-Gn, Co-Pog). Though the linear measurements are prone to magnification bias, we wonder if the difference in the linear measurements between the post- and pretreatment lateral cephalograms would have elucidated the skeletal effects of the fixed functional appliances. Moreover, angular measurements such as SNB and ANB are influenced by the rotational effects of the jaws relative to the cranial reference
planes (2). Can the effectiveness of the fixed functional appliance be based on these parameters? Effects of both rigid and flexible fixed functional appliances had been assessed in the nine articles reviewed. According to the authors, would the rigidity of the appliance bring about a difference in the treatment outcome?
References 1. Zymperdikas, V.F., Koretsi, V., Papageorgiou, S.N. and Papadopoulos, M.A. (2015) Treatment effects of fixed functional appliances in patients with Class II malocclusion: a systematic review and meta-analysis. European Journal of Orthodontics, http://dx.doi.org/10.1093/ejo/ cjv034. 2. Jacobson, A. (1975) The “Wits” appraisal of jaw disharmony. American Journal of Orthodontics, 67, 125–138.
