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ePaper created 2017-09-06, 09:11:22 | version 1.38.0
technique open bite closure Fig. 6a Fig. 6b plied in conjunction with anterior box elastics (1/4”, 4.5 oz, see Fig. 6b) from the labial aspects of the upper lateral incisors to the lower canines to facilitate a rapid open bite closure (Figs. 4a & b). This completes a system composed of four- components for rapid open bite closure. Why apply TS2? Normal swallowing takes place approximately 600 times/day or more (including during chew- ing and speaking) the tongue is generally posi- tioned in the palate. However, in anterior open bites the tongue fills the open bite space through anterior tongue positioning (previously referred to as tongue thrusting). TS2s are applied for both Rapid Open Bite Closure and for Rapid Lateral Open Bite Closure (Figs. 4a & b). They are used in conjunction with active self-ligating appliances due to the low resistance shown in vitro to permit free and controlled movement of the upper and lower anteriors. Once the incisors begin to develop a positive overbite relationship the tongue gen- erally begins to retract posteriorly into a more natural tongue position assuming the aetiology of the open bite has been additionally controlled (for example, nasal obstruction). When should TS2 be placed? TS2s are recommended at all ages including for both early interceptive treatment in children (Figs. 5a–f) and in adults. The ideal recommended time of placement is at the time of placement of active self-ligating brackets (that are regularly positioned on the labial aspects). TS2s and active self-ligating brackets work ideally and syner- gistically with specialised iArch wires that have a higher vertical dimension than horizontal dimension (for example .018” × .014”) to be closer to the centre of resistance for earlier incisor mo- ments of torque and control required for open bite correction. The archwires incorporate curve of Spee for the lower arches and reverse com- pensating curve on the upper arches to further facilitate incisor re-intrusion. TS2 incisor re- extrusion is further facilitated by the alignment of the anterior teeth, where a labial box elastic can be placed that also restrains the tongue (please see Fig. 6b). No clinically significant root resorption was found with the use of this light force system that reduces the unnatural and multi-directional anterior, superior, inferior and lateral tongue forces. How does TS2 work? The basic mechanism of action is that the TS2 produces a negative conditioning reflex response for anterior tongue positioning.2 This is similar to a hot-stove efect (Fig. 6a). However, due to the rounded ends of the nine protrusions the tongue is not lacerated, nor is the operator’s glove or skin. The feeling against the finger is one of coarse sandpaper as simply a reminder for the tongue to stay retracted away from the open bite. This permits the TS2s to work efectively in conjunction with the anterior box elastics (5/16”, 4.5 oz) for rapid open bite closure (ROC) shown in Figure 6b. In lateral open bite patients where the TS2s are placed at the premolars and molars crossbite elastics are applied, that are generally heavy 1/4”, 4.5 oz, to further prevent lateral tongue positioning while maxillary ex- pansion is completed simultaneously. In addi- tion, it is important that the patient is instructed to exercise swallowing with the tongue in the roof of the mouth from the day of TS2 placement. Figs. 6a & b The retraction reflex mechanism shown with TS2s (a). Application of anterior box elastics and active SL (b). 14 ortho 2/2017