12 Industry Clinical ORTHO TRIBUNE | NOv./DEC. 2009 Fig. 6: Patient, age 8. She had an open bite, which closed after 20 months treatment with a TRAINER Appliance (T4K). Lingual thrust present at the beginning of treatment was corrected, and her occlusion is stable after two years of treatment without using any retention. increasing the activity at the mentalis muscles, which pushes the lower lip up to reach the upper lip, which is generally short because of a lack in development of the upper orbicularis muscle. The TRAINER System Appliances have some elements on the anteroinferior area of the buccal shield that touch the internal mucosa of the lower lip when the lip is being raised by the mentalis muscles (Fig. 8). When the mucosa of the lower lip is stimulated by any element, the activity in the mentalis muscles is inhibited (Stavridi et al. 1992). Reducing the activity of the mentalis muscles increases the activity of the orbicularis due to the antagonism explained previously (Tosello et al. 1999). This way, development of the lip muscles is stimulated to produce a better and permanent lip seal through the activity of the lip muscles rather than the activity of the mentalis muscles (Fig. 4). f OT page 11 curved in deep-bite patients, tends to flatten, improving the vertical dimension (Fig. 5). Open bite On the other hand, open bite closes when treatment is performed with the appliances of the TRAINER System (Ramirez-Yañez et al. 2007). To understand how these appliances can produce a positive effect when treating open bites, it is necessary to understand the physiology of tongue posture. First, it is important to remember the tongue, the mandible and the hyoid bone are linked through a muscular system and work as a team. When the tongue is relaxed, its tip positions on the incisal papilla at the anterior part of the palate, which is its natural position when relaxed. With the tip of the tongue in this position, the dorsum of the tongue runs at the cervical third of the crowns and roots of the upper premolars. The base of the tongue goes downward at the molars, leading to insert at the hyoid bone. When the tongue is relaxed, the hyoid bone, where the anterior digatric muscle inserts, is positioned approximately between the third and fourth cervical vertebras, and antero-posteriorly, about the middle of the body of the mandible (Rocabado 1983; Tallgren and Solow 1987). The anterior digastric muscle, which is located between the mandibular symphysis and the hyoid bone, plays an important role in the growth and orientation of the mandible (Spyropoulos et al. 2002), as it loads the anterior area of the mandible. In patients with tongue thrust, the tongue is protruded. Therefore, the tip of the tongue is positioned forward and downward (the dorsum of the tongue comes downward and the base of the tongue moves forward). This causes the hyoid bone to move backward and upward (Ono et al. 1996; Haralabakis 1993), which stretches and increases the muscular activity of the anterior digastric muscle. Increasing the muscular activity of the anterior digastrics increases the pulling produced by that muscle on the anterior area of the mandible, pulling the mandibular symphysis backward and downward, stimulating a clockwise rotation of the mandible aggravating the open bite. AD Fig. 7: The lingual tab on the T4K is a key feature of each appliance as it stimulates the tip of the tongue and repositions the tongue in its physiological position. Fig. 8: T4K in place, assisting tongue positioning and lip seal and reducing mentalis activity. Thus, the effect observed when open bites are treated with the TRAINER System Appliances is produced in part by stimulating reeducation of the tongue posture, which is encouraged by the lingual tab located in the upper lingual area of these appliances. When the appliance is in the mouth, the lingual tab stimulates the tip of the tongue (Fig. 7). It does not position between the incisors or even downward, but at the area of the incisal papilla. As previously explained, when the tip of the tongue is at its physiological position, its dorsum and base tend to reposition at their physiological positions as well, with the base descending at the molar area. In this context, the hyoid bone locates in a better position, decreasing the activity in the anterior digastric muscle. Reducing the pulling at the anterior area of the mandible by the anterior digastric muscle, the mandible is not stimulated to rotate backward and downward anymore, and the muscles elevating the mandible may stimulate a counter-clockwise rotation, which help to close the open bite (Fig. 6). These significant results when treating open bite patients with the TRAINER System Appliances were explained by Usumez and colleagues (Usumez et al. 2004). They found a significant reduction in the angles FH-MP (frankfort/mandibular plane) and SN-GoGn (sella-nasion/gonion-gnathion), which means the Trainers produce in some way a counter-clockwise rotation of the mandible. Another effect contributing to the closure of open bites with the Trainers is that the appliance does not allow the tongue to position between the incisors teeth. This allows the teeth that are under-erupted to reerupt (secondary eruption process) with development of their dentoalveolar units at the anterior area of the mouth. Thus, the appliance of the TRAINER System helps to treat an open bite by re-educating the tongue to position in a more physiological pattern, therefore permitting a counter-clockwise rotation of the mandible as well as stimulating or permitting development at the dento-alveolar units at the incisors. Conclusions The various appliances of the TRAINER System work similarly, improving the muscular activity of the masticatory and facial muscles as well as re-educating the tongue to sit in a more physiological position when relaxed. By maintaining the mandible in a forward position during a period of approximately 10 hours per day, there is a change of the mandibular posture, which improves the sagittal aspect in those patients with a disto-occlusion. Through their action on the muscles of the cheeks and lips, the TRAINER System Appliances produce transverse development of the dental arches. Finally, through their action on the muscles closing the mouth and their action on the posture of the tongue, these appliances can improve the vertical aspect in those patients with either deep or open bite. Thus, it can be concluded that the appliances of the TRAINER System (including the MYOBRACE) are a valid alternative to treat malocclusions, as they improve the sagittal and transverse development of the maxilla and mandible as demonstrated by scientific research. These appliances also improve the muscular activity of the masticatory and facial muscles, as well as the posture of the tongue, as it has been shown in successful cases treated with the Trainers as well as published in the literature. There is ongoing research with the appliances of the TRAINER System to evaluate their action on the muscular activity of the muscles in the CMS, an action that has been already demonstrated with other functional maxillary orthopedics (FMO) appliances (Stavridi et al. 1992; Sessle et al. 1990). All changes produced in the mouth and the CMS by the Trainers permit the teeth to have more space and position better in the dental arches — in other words, to have better tooth alignment. The MYOg OT page 14 Lip seal One of the problems associated with mouth breathing and teeth crowding is unsealed lips. This is caused by a low muscular activity in the lip muscles (orbicularis). There is an antagonism between the orbicularis and the mentalis muscles; when the lip muscles reduce their activity, the mentalis muscles increase their activity and vice versa (Tosello et al. 1999; Lowe and Takada 1984). In patients who do not maintain a correct lip seal, the mentalis muscles maintain higher activity. So, the muscular activity at the orbicularis is very low or even non-existent. Lip seal is reached through