GAP Australasian Dentist Sept Oct 2020

Category Australasian Dentist 35 growth differential between the mandible and maxilla of an individual patient plays an enormous part in the status of the final molar relationship when a child reaches the permanent dentition and even beyond with further growth. (Figure 6) molars or even lead to their impaction – however if treatment is initiated at the appropriate age of 9 years and for a limited time. In such cases the second molars need to be monitored if treatment is completed prior to their eruption. Despite these limitations, extraoral traction is perhaps one of the most effective ways to obtain distal movement of maxillary molars and a successful nonextraction treatment plan. (Figure 7) tooth and hence biomechanically provides mostly a tipping force. It is very important that whatever treatment one proposes, one must take into account the patient’s age, compliance and most importantly one does not over treat at this particular point in time, especially if we can still correct these issues at a later age more effectively ,predictably and reduce the amount of time in orthodontic treatment if other orthodontic issues are present and those issues need to be addressed and corrected – which is generally the case due to crowding, spacing, deep overbite, crossbite etc Hence in my practice, I would usually only treat a developing Class II at an early age i.e. prior to the age of 10 if it was affecting the developing malocclusion, such as a significant mesial drift of the upper posterior segment causing a lack of space for the eruption of future permanent teeth. Otherwise I would generally treat most of these Class II malocclusions in the late mixed dentition or permanent dentition in conjunction with other orthodontic treatment to resolve all their issues. Treatment of the Class 2 patient who presents in the late mixed dentition and in the permanent dentition (who are still growing) will be addressed in the second part of this series. u Dr Geoffrey Hall, Specialist Orthodontist B.D.Sc(Melb) Cert.Orth( Uni Of Penn) MRACDS (ORTH) Director OrthoED Institute geoff@orthoed.com.au Ph: 03 9108 0475 / 1300 073 427 clinical Figure 6 Change in terminal plane relationship based on growth and shift of teeth Based on a significant amount of research we now know the following: A. Only 24% of young children have a flush terminal plane, and with those children 56% proceed to a Class1 molar relationship whilst 44% end up with a class II molar relationship. B. The greater the mesial step in the primary and early mixed dentition the greater the chance of a class III buccal relationship occurring C. Approximately 10% of individuals have a distal step occlusion – and ALL these turn into a class II buccal relationship What are our options in dealing with the very young child who has a developing class II buccal relationship? A. Removable compliance appliances i. Headgear: During the early mixed dentition, Headgear can retard or even halt the forward growth of the maxilla (also allowing favourable differential growth of the mandible) and assist in moving maxillary teeth distally to correct developing Class II relationships. It has some demonstrable important advantages. These include maximum anchorage, ability to adjust the force levels, and control of bodily or tipping movement. It can assist in correcting transverse deficiencies by expanding the inner bow. The extrusive component of the cervical headgear will allow for bite opening in deep bite patients. If vertical control is a concern in a high- angle patient, a high-pull facebow headgear will control the extrusive force component. Prolonged use of headgear can delay the eruption of maxillary second Cervical High-pull Figure 7 Different types of Headgear Figure 8 Cetlin plate ii) Removeable plates Removeable plates such as the Cetlin plate can tip the molars distally – however they are only useful for tipping the crowns distally and to provide stability it is essential to then move the root distally. This is usually accomplished with Headgear and altering the position of the outer bow accordingly. (Figure 8 Cetlin plate) Figure 10 Distal Jet appliance Figure 9 Pendulum appliance B. Fixed distalising appliances These are generally used in potentially a non-compliant patient to distalise upper molars to correct a Class 2 relationship to Class 1. Pendulum and Distal Jet appliances are examples of those fixed noncompliance appliances. (Figure 9) (Figure 10) However even though it has been advocated that these appliances provide a bodily movement, the force generated is above the Centre Of Resistance (CR) of the