This study illustrates a simple effective method (2x4) appliance for early treatment of pseudo Class III malocclusion in mixed dentition.
It also emphasises treatment planning and treatment sequence.
It highlights the advantage of early treatment of pseudo Class III malocclusion by following up the cases for a period of 4 years.
To illustrate a simple effective method for early treatment of pseudo Class III in the mixed dentition and to highlight the advantages of early treatment by showing a 4-year follow-up of the treatment effects.
Twenty-one consecutive southern Chinese patients with a mean age of 9.6 years were included in the early treated group with pseudo Class III malocclusion.
Lateral cephalometric films taken at the beginning and at the end of treatment were analysed. The arithmetic mean and standard deviation (SD) were calculated for each cephalometric variable and paired t-tests were performed to assess the statistical significance of the treatment effects.
Anterior crossbites and mandibular displacements were eliminated after the treatment. The angulation of the upper incisors to the maxillary plane showed an increase by a mean of 9.5° (P < 0.001), while the angulation of the lower incisors to the mandibular plane showed a decrease by a mean of 4.9° (P < 0.001).
In pseudo Class III malocclusion, proclination of upper incisors and/or retroclination of lower incisors with simple fixed appliances contribute to the correction of anterior crossbite and the elimination of mandibular displacement. Proclination of upper incisors, use of Leeway space and arch width increase provide space required for the eruption of the premolars and canines.
Management of pseudo Class III malocclusion in southern Chinese children Rabie A B M and Gu Y Br Dent J 1999; 186: 183–187
Early correction of upper incisors in lingual occlusion is desirable to minimise attrition of the labial surfaces of the upper incisors, periodontal problems and to allow the later erupting teeth to come into occlusion on an undisplaced jaw relationship.
This correction may be achieved using removable, functional or fixed appliances or with extra-oral devices such as a face mask or chincap. The method described has the advantage of being simple and does not involve any extra-oral mechanism. It also neatly answers the problem of retention which bedevils removable appliances when deciduous molars have been extracted.
British readers will be intrigued by the unaccustomed cephalometric values. There seems little doubt, however, that the appliance is effective in proclining upper incisors. What is surprising is the significant retroclination of lower incisors in view of the fact that only two patients had appliance therapy in the lower arch. It would appear that the development of a substantial overbite has maintained the corrected incisor relationship and this has resulted in the lower incisors being tipped lingually. This sort of effect is well-known and I remember being taught this as an undergraduate student all those years ago.
Other eye-catching cephalometric values are the very small changes in SNB and ANB which raises the question of whether the patients had an initial displacement.
The authors claim that the use of an upper fixed appliance with rectangular wire permits palatal root torquing of upper incisors. It is not immediately obvious why they should want to do this in Class III cases and the amount of torquing cannot be substantial over a period of 2–3 months. In an appliance of this kind, palatal root torque is the same as labial crown torque if the archwire is not restrained and labial crown torque is the tooth movement which occurs most readily.
There is nothing new in the 2×4 fixed appliances but it is interesting to see how effective it can be in Chinese children, and I would heartily endorse the concept of treating postural Class III malocclusion at the earliest possible stage.
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Richardson, A. Early Treatment of pseudo Class III malocclusion in mixed dentition. Br Dent J 186, 177 (1999) doi:10.1038/sj.bdj.4800056a2
American Journal of Orthodontics and Dentofacial Orthopedics (2015)