Year : 2006 | Volume
: 24 | Issue : 2 | Page : 80--83
Is tongue thrust that develops during orthodontic treatment an unrecognized potential road block?
HS Chawla1, Sanjay Suri2, A Utreja2,
1 Deptt. of Oral Health Sciences, Oral Health Sciences Center, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012, India
2 Oral Health Sciences Center, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012, India
Oral Health Sciences Center, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
The role of tongue thrust has often been suspected, long debated and largely dispelled as a primary etiological factor of malocclusion. However, tongue thrust may contribute to poor occlusal intercuspation both during and after treatment. A tongue thrust may also develop during orthodontic mechanotherapy as a result of the transient creation of intra and interarch spaces and this little recognized phenomenon was found to occur in many randomly followed cases. In many instances, this seemingly adaptive and secondary response of the tongue posture and function may persist and thereafter impede the resolution of intra and interarch problems.
|How to cite this article:|
Chawla H S, Suri S, Utreja A. Is tongue thrust that develops during orthodontic treatment an unrecognized potential road block?.J Indian Soc Pedod Prev Dent 2006;24:80-83
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Chawla H S, Suri S, Utreja A. Is tongue thrust that develops during orthodontic treatment an unrecognized potential road block?. J Indian Soc Pedod Prev Dent [serial online] 2006 [cited 2020 Jul 6 ];24:80-83
Available from: http://www.jisppd.com/text.asp?2006/24/2/80/26021
Comprehensive orthodontic treatment involves sequenced delivery of tooth moving forces and application of sound biomechanical principles, which when successful, culminate in transforming the malocclusion state to optimal occlusion and improved esthetics, function and stability. Refinements in present day appliances and techniques have significantly improved the standards of treatment with minimal complications and lead to achieving treatment goals in an expeditious manner. The preadjusted appliance as it is used today is an example of such progress. However, during treatment with fixed appliances and especially so with the preadjusted appliance, anchorage preservation is very important to avoid treatment compromises and even failures. In cases where anchorage preservation is critical, any additional factor that tends to tax the anchorage, howsoever small its individual influence, may cumulatively impact the treatment outcome and thus its role becomes important. Tongue thrust which develops during orthodontic treatment is one such a factor that often gets overlooked during orthodontic mechanotherapy. We observed that tongue thrust often develops during routine comprehensive orthodontic treatment subsequent to bite opening and after the creation of extraction spaces. This observation was seen in many cases that were followed prospectively in treatment.
Abnormal tongue function and posture have been long debated as a cause of malocclusion. Lefoulon, in 1839, appreciated that among the causes of irregularities of teeth were "sounds of speech in which the tongue strikes against the upper anterior teeth, pushing them forward." Desirabode's article published in 1843, is the first known reference to the fact that the lips on the outside and the tongue on the inside of the mouth constitute a balance of forces that retain the teeth in their position. In 1859, Bridgeman described irregularities of the teeth due to external muscle forces (of the lips and cheeks), internal muscle forces (of the tongue) and occlusal forces. At the turn of the nineteenth century, Angle had recognized the problems of the muscular environment of the dental arches and had noted: "We are just beginning to realize how common and varied are the vicious habits of the lips and tongue, how powerful and persistent they are to overcome." Rogers advocated myofunctional for harnessing muscle forces to treat malocclusions. Tweed acknowledged that abnormal muscle function was a major factor in relapse. Although he did not know how much muscle function could be altered through orthodontic procedures, nevertheless, he advocated that treatment should try to overcome the perverted muscle and tongue habits. To answer the specific question of how significant a role does tongue thrust that develops during orthodontic treatment have in taxing the anchorage, there are no data available in the literature.
A simple definition of tongue thrust might be stated as follows: 'The forward movement of the tongue tip between the teeth to meet the lower lip, in deglutition and in sounds of speech so that the tongue becomes interdental.' This does not include consideration of forward tongue posture, which has a more important role. Tulley proposed a working clinical classification of tongue thrust. According to him, the main types are: tongue thrusting as a habit; tongue thrusting which is possibly endogenous or innate; tongue thrust as an adaptive behavior; and pathologic and grossly abnormal tongue problems. Of these, tongue thrust habit and tongue thrust as an adaptive behavior are amenable to correction with orthodontic treatment or natural growth placing the labial segments in good relationship.
It is widely held that as patients who have a tongue thrust before treatment grow, their airway size increases and the tongue can assume a more posterior position. Also, as the dental environment that may have supported the habit is improved with orthodontic treatment, the tongue and lip musculature adapt to the improved environment and normal function begins to occur. As a result, about 80% of tongue-thrust habits usually correct themselves before the finishing stage of orthodontic treatment. However, patients with severe habits should be referred for myofunctional therapy early in treatment or even before treatment.
In Tulley's cross sectional study of 1,500 12 year old schoolchildren selected as a true random sample, only twelve children had a complex problem of tongue behavior and children of this group had an adverse skeletal pattern with high maxillary-mandibular plane angles. Another twelve children were seen to have a tongue thrust in speech, but all had ideal occlusion. Forward tongue posture may be sufficient to prevent vertical eruption of the anterior teeth and thus result in an anterior open-bite malocclusion. Numerous investigators have studied the pressures exerted by the tongue.,,,,,,,,,,, The importance of tongue pressures during function and rest is significant especially with the knowledge that very low forces are sufficient to move teeth if applied over a sufficient period of time. Studies of tongue and lip pressure have suggested that the pressure created at rest may have an influence on dental arch form and tooth position.,, In a limited number of cases with poor facial pattern associated with forward tongue posture at rest, an anterior openbite may not be permanently reduced, whatever the method of treatment. This clinical type is very unfavorable for treatment, but fortunately occurs in only about 0.6% of the population.
There is central coordination of the timing of jaw, lip and tongue muscles during chewing., Electromyographic studies of tongue function have shown that genioglossus muscle activity ceases when teeth are in intercuspation, with a simultaneous peak in activity of the auricular temporalis muscle and gradually increases during jaw opening to peak immediately before maximum opening of jaw position., Thus, lack of proper intercuspation during the initial parts of mechanotherapy can lead to the development of tongue thrust.
Interceptive attempts to contain tongue thrust have conventionally involved suggestions to the patient, myofunctional exercises and a gamut of appliances such as cribs, rakes, overlay bite plates, interocclusal elastics, maxillary expanders and loose fitting training appliances. Myofunctional therapy is indicated in severe situations as soon as the child is able to understand the problem and cooperate with the therapist. Often the orthodontist can instruct the child in the proper way of swallowing and this knowledge, coupled with changes in the relationships of teeth during orthodontic treatment, can correct the problem. Increased patient awareness of occlusion also aids in controlling tongue thrust in swallowing and speaking.
Development of tongue thrust during orthodontic treatment
While the role of tongue thrust as a major cause of malocclusion per se has largely been dispelled, yet, the fact that tongue thrust and tongue posture may impede tooth eruption sufficiently to cause an anterior open bite and may have an influence on dental arch form and tooth position indicates that in the event of its development during treatment, tongue thrust may obstruct desirable tooth movements during orthodontic treatment and may contribute to loss of anchorage. The leveling and aligning phase of fixed mechanotherapy is commonly followed by bite opening as the next phase of tooth movement. Leveling can sometimes lead to a transient increase in overjet when the bite may be over closed pretreatment due to severely retroclined upper anterior teeth. In many situations, as a result of the bite-opening or transient increase in overjet during the early phases of treatment, tongue thrust develops as a secondary feature, though it was not present pretreatment [Figure 1]. It may also begin when treatment requires creation of temporary open spaces or leads to interferences with intercuspation [Figure 2]. Such thrusting may be transitory or permanent. It is noteworthy that tongue thrust developed in many of the patients. Randomly followed prospectively, who did not have a tongue thrust before treatment. This has led us to start prospectively examining patients to evaluate the development of tongue thrust during routine orthodontic treatment involving a larger number of patients of various facial types and malocclusions, its management and the effects thereof.
Thus, even though it may not be a cause of the original presenting malocclusion, a tongue thrust, which develops mid-treatment in this fashion may slow down the treatment and may start to tell on the anchorage. In the majority of cases, it may go unnoticed and anchor loss may continue unchecked. The problem is certainly an added difficulty in managing high mandibular plane angle cases. Additionally, tongue thrust and open bite problems are more common and more difficult to treat in high mandibular plane angle cases. An inadvertent increase in the vertical of a high mandibular plane angle case can cause the mandible to rotate open dramatically. This rotation and the tongue thrust may couple to form a vicious cycle, which is of great disadvantage to the high angle patient.
Pre-empting the situation may be the best way to prevent the problem. In high angle Class II patients, where bite opening and retraction may be goals of the treatment plan, treatment mechanics should be paced in such a way that tongue thrust is discouraged and in those cases where it is evident (to vigilant inspection), mechanics should be modified and myofunctional exercises instituted to prevent deleterious effects such as anchor loss. The methods applied may include any or all of the following: slow bite opening; avoiding stepwise retraction of the mandibular anterior teeth first while leaving the maxillary anteriors proclined and/or protruded to be corrected later (which will be conducive to developing an overjet); intervening with the institution of popping myotherapeutic tongue exercises and training in correct swallowing techniques in the early stages of treatment, if tongue thrust is seen to develop. We have found that a method of show (the presence of tongue thrust), tell (about the problem and potential benefits of the exercise) and do (demonstration of correct swallowing and making the patient practice the same, seated in the dental chair and under supervision) with a fortnightly scheduled reinforcement, is very helpful to curb the habit in most patients.
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