Volume 35 Number 1 pp. 5-17 2009

Tutorial

Did you know? A question and answer dialogue for the orofacial myologist

Robert M. Mason (Duke University Medical Center, [email protected])

Ellen B. Role ([email protected])

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Suggested Citation Mason, R. M., & Role, E. B. (2009). Did you know? A question and answer dialogue for the orofacial myologist. International Journal of Orofacial Myology, 35(1), 5-17. DOI: https://doi.org/10.52010/ijom.2009.35.1.1

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

The views expressed in this article are those of the authors and do not necessarily reflect the policies or positions of the International Association of Orofacial Myology (IAOM). Identification of specific oducts,pr programs, or equipment does not constitute or imply endorsement by the authors or the IAOM. International Journal of Orofacial Myology 2009, V35

DID YOU KNOW? A QUESTION AND ANSWER DIALOGUE FOR THE OROFACIAL MYOLOGIST

ROBERT M. MASON, D.M.D., PH.D., and ELLEN B. ROLE, M.A.

ABSTRACT This article addresses selected concepts and procedures related to orofacial myology in a question and answer format. Topics include tongue-tip placement for swallowing; a masseter- contraction swallow; temporary devices utilized in orthodontic treatment; relapse following orthodontic treatment; some advantages and disadvantages of fixed and removable orthodontic appliances; the extraction of teeth in orthodontic treatment; posterior and anterior considerations; and the importance of recasting the emphasis and focus of myofunctional therapy to orofacial rest posture therapy. In addition, this article promotes projects that orofacial myologists and orthodontists can mutually undertake to assist in advancing the data base regarding orofacial myofunctional disorders, thereby serving to enhance the reputation and value of orofacial myofunctional therapy within the dental profession.

KEY WORDS: orofacial myofunctional therapy; orofacial myology; tongue-tip elevation to rugae; masseter contractions; the spot, swallowing therapy; fixed and removable orthodontic appliances; extraction of teeth; dental and skeletal crossbites; interdisciplinary projects.

INTRODUCTION

The purpose of this article is to address and correct swallow pattern. Individuals learn oral answer questions related to selected concepts performance skills faster when there is tactile and procedures of interest to the orofacial feedback, as opposed to kinesthetic or myologist. It is hoped that the information proprioceptive feedback (Grossman and Hattis, presented will serve to enhance and support the 1967). clinical activities of orofacial myofunctional clinicians. The discussions provided in this article Did you know? Knowing that a tongue-tip down are the opinions of the authors and therefore may position usually matures into a tongue-tip-up not represent the views of all members of the against the “spot” position with age, the orofacial IAOM. myologist may be surprised to learn that not all normal individuals with normal dental arches naturally elevate the tongue-tip to the "spot" for QUESTION: Should every individual be taught the initiation of a swallow or for resting posture. to make a tongue-tip contact against ‘the For some normal individuals, the tongue-tip does spot’ during the initiation of a swallow? not elevate for a swallow, even as the mid-portion and back of the tongue elevates. A tongue-tip ANSWER: Teaching individuals to make a down rest and swallow pattern can be considered tongue-tip contact against the “spot” is a logical as an economical pattern for the tongue-tip. and time-honored therapy technique (Hanson Others may make a contact against the lower and Mason, 2003). The “spot” is the shorthand incisors in the initiation phase of a swallow word of the orofacial myologist to describe the (Mason, 2007). These differences should not be maxillary anterior alveolus at the area of the hard considered abnormal behaviors. A contact palatal rugae (also known as the palatal relationship of tongue-tip with lower incisors fingerprints). Touching the tongue-tip against the during a swallow will not result in flaring of the spot results in a tactile feedback sensation that lower incisors. The duration of contact of the can facilitate learning and habituate a

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tongue-tip against the teeth during a swallow is contractions. The range of normal for swallowing fleeting, and swallow pressures do not add up or certainly includes a lack of masseter contraction compound over time. with teeth apart as a characteristic of normal swallows. This includes normal individuals Even though a low tongue-tip rest or functional performing swallows of a bolus of food or liquid. position for swallowing may be a normal variation, a tongue-tip down posture and behavior An important clinical perspective regarding the may be related to abnormalities such as decision to teach a masseter contraction/teeth- , large mandibular tori, syndromes together swallow should include the recognition with structural or functional features, a history of that many children have a small oral isthmus nasal airway problems, or other conditions that area. The oral isthmus is bounded superiorly by can affect the orofacial complex and hamper the the soft palate, inferiorly by the base of the ability of some individuals to elevate the tongue- tongue, and laterally by the faucial pillars, or tip. A thorough examination should reveal faucial tonsils when present. The oral isthmus whether or not patients are able to elevate the area can be reduced in size by a long soft palate, tongue-tip. large faucial tonsils, or a high-riding posterior tongue associated with a short ramus of the When all of the previous information is . With normal growth, the area of the considered, the time-honored method of teaching oral isthmus enlarges due to the vertical growth a correct swallow should begin with redirecting of the mandibular ramus, the lengthening of the the tongue-tip to a better location. With pharyngeal tube, the dropping down of the base appreciation for individual differences and of the tongue and hyoid bone, and involution of therapeutic needs, what better choice is there the faucial tonsils and adenoid mass. than to elevate the tongue-tip to the rugae area? A child with a size reduction of the oral isthmus is QUESTION: Is it necessary to teach masseter not usually a good candidate to utilize a closed- muscle contractions (closed-teeth contacts) teeth swallow because this serves to further in swallowing therapy? restrict the size of the isthmus. For some children, swallowing with a tongue forward ANSWER: Teaching individuals who exhibit gesture while a bolus of food passes through the difficulty with swallowing to achieve masseter oral isthmus may be the best way to swallow contractions during a swallow makes sense for a under the circumstances. Thrusting as a way of variety of reasons. There are various patterns of enlarging the oral isthmus has a purpose parallel swallowing: food-consumption swallowing, saliva to the thrusting seen in some patients with swallowing, sip swallowing, and sequential liquid (TMJ) problems who use drinking swallowing (“chug-a-lugging”). The a forward tongue thrust as a mechanism to reason that the teeth are brought together firmly protect the temporomandibular joints. during some swallowing is to bring momentary stability to the oral cavity so that the peristaltic A thorough oral examination can identify children motion of the tongue can easily move the bolus in whose treatment for tongue thrust swallows a posterior direction. A closed-teeth swallowing should be deferred, or who should not be taught pattern stabilizes the oral cavity, and this stability a teeth-together swallow in light of the reduced can be accomplished swiftly as it falls into the dimensions of the oral isthmus. Patients with rhythm of the masticatory process. This therapy temporomandibular dysfunction (TMD) symptoms activity of bringing the teeth together is not are also questionable candidates for masseter required, but can aid in the voluntary control of a exercises. In our view, teaching a masseter swallow during the teaching and habituation contraction swallow is contraindicated for TMD phases. Learning to take sips and not protrude patients. The fact that not all individuals contract or lateralize the mandible is also facilitated with a the masseters during swallowing should not teeth-together swallow. diminish the therapeutic value of continuing to teach this concept as a part of therapy. As used Did you know? As mentioned, not all individuals with patients with orofacial myofunctional swallow by closing the bite with masseter muscle problems, the masseter contraction (closed-teeth)

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technique remains a useful staple of the marketing tool to describe the value of your myofunctional clinician. services. Identifying the ‘causes’ of relapse, however, should be carefully stated, or in most cases, avoided by orofacial myologists. QUESTION: Many orthodontists are reporting the use of TAD’s in their clinical procedures. Did you know? There are many factors besides What does this mean? tongue posture or function that can account for orthodontic relapse. Let's appreciate these ANSWER: A temporary (bone-supported) factors by first explaining why retention is anchorage device (TAD) is now used by many necessary following . Retention is orthodontists. These devices are referred to as necessary for three primary reasons, the second miniscrews, micro-implants, anchor screws, of which is specific to the work of the orofacial miniplates, or by other terms introduced into the myologist: (1) the gingival and periodontal tissues scientific literature by various authors. The TAD are affected by orthodontic tooth movement and is inserted into the maxilla or mandible (mostly require time for reorganization after the the maxilla) as a means of achieving orthodontic orthodontic appliances are removed; (2) the teeth anchorage for bodily movement of selected teeth. may be in an inherently unstable position after They are removed after biomechanical therapy. treatment, so that habitual soft tissue pressures constantly produce a relapse tendency; and (3) Did you know? A miniscrew placed high in the changes produced by growth may alter the maxillary cortical bone above a molar can be orthodontic treatment result (Proffit and Fields, used to intrude a molar with a spring or elastic 2000). attached between the tooth and the screw, or can be used as an alternate to headgear to retract A significant patient sample linked to relapse anterior teeth. The various placement options for following orthodontics involves patients with the miniscrew provide many more treatment skeletal . Those who have advantages than available with typical elastic declined surgery and are being treated by wear or headgear. orthodontics alone rather than agreeing to orthodontics and surgical repositioning are QUESTION: What points are important for the more susceptible to relapse in retention. The orofacial myologist to consider when decision for surgery or not, after all, resides with discussing why teeth relapse following the patient. The orthodontist, under these orthodontic treatment? circumstances, will present two treatment plans: 1) an ideal plan involving a combination of ANSWER: It is not recommended that you tell an orthodontics and jaw surgery; and 2) a “practical” orthodontist why you think a specific patient is or “compromised” plan that can likely improve the exhibiting relapse following orthodontics. It is bite, but with a greater possibility of relapse if the appropriate, however, to report your findings of dentition is not ideally situated over the alveolar the factors you have identified, the correction of bone in which it resides. An example is a mild or which would create or recapture an oral moderate Class III skeletal with environment compatible with stability of the mandibular . To bring the bite dentition. The orofacial myologist evaluates together by orthodontics alone, Class III patients with a different protocol of examination would be used, but as well, the lower incisors than evaluation protocols used in . A would have some lingual crown tilt while upper major difference between dental treatment incisors would be flared forward to some degree (especially orthodontics), and an orofacial to maintain a contact relationship with lower myologist’s treatment is that those in dentistry incisors. These final positions of the incisors are evaluate and treat to teeth-together relationships, not likely to be stable. Some relapse will likely whereas the orofacial myologist is concerned with occur if the patient does not cooperate well with teeth-apart postures and behaviors that are not the longer period of retention that would be compatible with dental stability (Mason, 2005). required following active orthodontics. Also, This distinction between dentists/orthodontists additional post-pubertal mandibular growth, which and orofacial myologists should be a key can be seen well into the twenties in some

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individuals, can further contribute to negative source of the problem. Thus, caution is urged for changes in the bite. the orofacial myologist not to presume about the causes of relapse. Nonetheless, your thoughts Some other specific factors that can account for about how you may be able to stabilize the relapse following orthodontics are: (1) poor dentition for a given patient are valuable. It is resting relationship between the lower lip and strongly recommended that you find out all you upper incisors (the lower lip at rest should cover can from the treating dentist about the original 2-3 mm of upper incisor teeth, whether or not problem list, especially with regard to whether there is lip competence (Vig and Cohen, 1979; there was a skeletal malocclusion treated without Mason, 2008); (2) lower incisors moved too far surgery, or whether teeth were extracted or not. forward with Class II elastic treatment (Proffit and Fields, 2000); (3) intercanine width expansion If a patient's freeway space is habitually open during treatment; (4) late growth into open bite beyond the normal range, you have a strong (Proffit and Fields, 2000); (5) unresolved issues basis for discussing this posture with your dental involving the airway (Franklin, 2008); and (6) lack referral sources since an open freeway space of appliance compliance. Lack of patient beyond the normal 2-3 mm range posteriorly, or cooperation during the retention stage of 5-6 mm anteriorly, becomes a significant factor orthodontics can potentially compromise the that can lead to dental relapse (Mason, 2005). If orthodontic result. The orofacial myologist can the airway is clear, orofacial myologists can focus be instrumental in encouraging the patient to therapy to establish a normal vertical dimension adhere to the orthodontic retention guidelines as an important way to prevent further relapse or prescribed by the orthodontist. to recapture a normal oral environment at rest. This would logically also include therapy to Another source of potential relapse is closing eliminate a forward, interdental rest posture of the anterior open bites with vertical elastics while tongue. also extruding the lower incisors (Pepicelli, Woods, and Briggs, 2005). While these QUESTION: What are the advantages and orthodontic maneuvers are often necessary disadvantages of fixed and removable procedures in orthodontics, they are sometimes appliances in orthodontics? undertaken without full appreciation for the effects of the opposing forces of the strap ANSWER: Contemporary orthodontic treatment muscles of the neck that can serve to reopen the involves the use of fixed and removable bite in retention. The current use of TAD’s in the appliance systems. In traditional orthodontic maxilla to intrude posterior maxillary teeth may care, removable appliances play a supporting help to reduce the impact of the strap muscles of role in comprehensive treatment. They are useful the neck as a contributor to post treatment for the preliminary treatment with preadolescents relapse with open bite correction. or for adjunctive treatments for adults, and are employed routinely in retention (Proffit and Fields, Late growth vertically or (especially) horizontally 2000). A variety of functional appliances can also contribute significantly to relapse continues to be indicated for selective growth following orthodontics. To evaluate this and other modification efforts. possible contributing factors, orthodontists use cephalometric films and dental casts to identify, Over the past ten years, the advent of the through superimpositions, the nature and sources Invisalign® system of removable appliances has of relapse. Merely observing a patient in your provided an alternative to traditional braces for office does not provide a valid cause-and-effect many adults, and recently also for adolescent relationship about relapse, especially when a patients. The Invisalign® and other competing prominent tongue is noted which could be an systems employ a series of removable adaptation to the result of the relapse. The appliances called “aligners” which are tongue forward rest posture may be an example constructed from dental casts; each aligner is of tongue thrusting becoming an ‘opportunistic’ modified slightly to facilitate movement of a behavior; that is, filling the space created by particular tooth or teeth. There may be as few as other biological events rather than being the 3 aligners to as many as 20 sets involved,

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depending upon the system. The Invisalign® (Proffit and Fields, 2000). The Begg appliance aligners were originally intended for use only by fell out of use in orthodontics because of the orthodontists, although they are now marketed extended treatment time involved and the inability and used by many in general and pediatric to selectively derotate, extrude, or intrude teeth. dentistry. The treatment costs vary; they may parallel or even surpass the fees for conventional The most current palatal/lingual fixed appliance, fixed orthodontic treatment. the ALF (Advanced Lightwire Functional) appliance, was developed by general dentist Did you know? Removable appliances have Darick Nordstrom in the early 1980's. The ALF is three primary advantages: (1) they can be advertised by its advocates as being an removed easily by the patient (this advantage is orthopedic/orthodontic appliance that integrates especially attractive to patients in social cranial, structural, body, and nutritional concepts. situations, and also, oral hygiene measures This light wire appliance is purported to influence become easier with the appliances removed); (2) the skull bones and teeth and can correct the appliances can be constructed in the structural distortions of the skull and correct laboratory rather than in the mouth at chair side; alignment of upper and lower teeth. Advocates and (3) some types of growth guidance contend that the correction of malpositions of the treatments can be carried out with removable teeth with the ALF can also positively affect the appliances more easily than with fixed upper neck, shoulders, lower back, as well as appliances. other functions. While these claims for the ALF remain controversial, the ALF is an appliance There are also some obvious disadvantages to system used primarily by non-orthodontists that removable appliances: (1) the appliances can has utility for a variety of orthodontic conditions. only work when patients wear them, so patient compliance is a recurring issue (the orofacial myologist may assist in motivating and supporting Current orthodontic practices: Contemporary the patient to become more compliant); (2) the treatment in orthodontics involves fixed appliances present problems in applying the two- attachments for all teeth using an edgewise point contacts on teeth that are necessary to appliance characterized by bracket slots that are produce complex tooth movements, so the torqued, offset and angulated, which reduce the appliance itself may limit the possibilities for need for routine first, second, and third order treatment (Proffit and Fields, 2000). Because of bends in archwires. Fixed orthodontic treatment these limitations, current comprehensive provides a highly controlled system for moving orthodontic treatment is dominated by fixed, non- teeth forward, back, up, or down. Advances over removable appliances. time with the progression of improvements of the edgewise appliance include automatic rotational A brief review of removable appliance control, alterations in bracket slot dimensions, systems to correct malocclusions: One of the straight-wire prescriptions, self-ligating brackets, first removable appliances used in orthodontics lingual appliances, and clear or tooth-colored was developed by George Crozat in the early appliances (Proffit and Fields, 2000). With fixed 1900's. The appliance was fabricated out of appliances, the entire can also be precious metals. Clasps were constructed for the moved mesially (toward the midline) or distally molars and heavy gold wire was used for the (toward the back of the dental arch) with the use framework. Lighter gold wires were used as of elastics or other orthopedic means. The finger springs to move teeth. With the concept of “anchorage” takes on a variety of development of refinements with fixed meanings and opportunities with fixed appliances appliances, interest in the Crozat waned. In the in place, since quadrants of teeth can be used to 1960's, there was a wave of enthusiasm among anchor the front or back of the dentition when some for the Begg appliance system. This specific movements are needed. The corrections system utilized a variety of creative springs of rotations, vertical discrepancies and the attached to a removable acrylic appliance. opportunity to build in selected angulations for 's system was more efficient than individual tooth movements are also easily the edgewise fixed appliance system of that time controlled with fixed appliances.

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QUESTION: What is the basis of the may be instances where extractions have been controversy about extracting teeth in imprudently recommended by orthodontists and orthodontic treatment? non-orthodontists without due regard for the impact of extractions on the facial profile, ANSWER: It can be very confusing to orofacial orofacial myologists should resist reaching the myologists to hear claims by some in dentistry inappropriate conclusion that extractions for that extractions are never indicated. Over the orthodontic treatment are always contraindicated. past several years, many non-orthodontists have claimed that extracting teeth as part of One of the primary purposes of the tongue is to orthodontic treatment results in compromising a maintain the airway for breathing. The view that patient’s genetic potential for growth of the . maxillary extractions inhibit the tongue space and They further maintain that retraction of anterior push the tongue posteriorly ignores the adaptive teeth following extractions results in the skull capacity of the tongue to respond to changes in being “jammed” as the contents of the skull the size of the oral cavity from growth and become compressed, creating neurologic and development, extractions, or from surgical jaw structural problems (International Center for manipulations. An eloquent case in point is the Nutritional Research, 2009). There is also the individual with mandibular prognathism who also claim by some non-orthodontists that extracting has a clinically-large appearance of the tongue. maxillary teeth for orthodontic treatment purposes Following mandibular setback surgery, the serves to compromise the size of the oral cavity, tongue appears smaller as viewed by intraoral forcing the tongue to be displaced posteriorly and inspection. What has transpired is that the creating a risk of sleep apnea from airway tongue, mandible, hyoid, and cervical muscles interference. have adapted to their altered spatial and functional environment (Wickwire et al, 1972). The extraction of selected teeth for orthodontic treatment purposes has been practiced A patient with severe maxillary protrusion who successfully for 100 years without the negative has had maxillary bicuspids extracted undergoes effects claimed by some outside of the a similar process of muscular adaptation. As the orthodontic community. In fact, expansion of the maxillary anterior teeth are retracted, the tongue dental arches without extractions can produce a and surrounding musculature adapt to the new very unstable long-term orthodontic result (Proffit, environment in all planes of space. The airway Fields & Sarver, 2006). It is hoped that every remains protected. orofacial myologist knows that extracting teeth for orthodontic treatment purposes is appropriate Orofacial myologists must be wary of embracing under a variety of circumstances. Certainly, the views of those who recommend extractions in extractions should be determined on an individual all patients, or in no patients. Every patient basis. If a patient shows incisor protrusions to should be considered individually, and extraction the extent that the lips cannot be closed without of teeth will be appropriate for some and muscle strain, extractions will likely be indicated. contraindicated for others. In instances where there are missing teeth, supernumerary teeth, or ankylosed primary QUESTION: What should the orofacial molars with no permanent successors, extraction myologist know about posterior dental of such teeth with small roots may be indicated crossbites? and the resultant spaces are then closed by orthodontic means, dental implants, or by fixed or ANSWER: A crossbite occurs when a maxillary removable prosthetic appliances. tooth does not exhibit overjet and in relationship to an opposing lower tooth or teeth. Did you know? The consideration for The concepts of overbite and overjet are extractions should always be made with regard to applicable around the entire dental arches. The the impact on the profile. The anterior dentition maxillary tooth/teeth may be positioned toward influences the profile. The projection forward of the palate, or mandibular tooth/teeth may be anterior teeth provides support for the lips and positioned toward the cheeks or lips. A posterior determines lip posture and position. While there crossbite may appear as a dental deviation alone,

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or may be the result of a jaw discrepancy such as (Franklin, 2008). The chances for successful mandibular prognathism, or narrowing of the treatment of tongue and lip postures and maxillary arch. Such crossbites may be functions are destined to failure without first described as ‘skeletal crossbites;’ deviations in treating the underlying physical problems the position of a jaw or jaws associated with a (Franklin, 2008). The exception is elimination of skeletal deformity. a retained sucking habit in a young child. As is well known, the cessation of sucking can often A common crossbite situation seen with patients result in some spontaneous resolution of a who exhibit orofacial myofunctional disorders is a developing posterior crossbite or anterior open posterior crossbite associated with a high, narrow bite. As the freeway space is normalized, normal hard palate. In such instances, the crossbite can processes of dental growth and development are be linked to the disorder by restricting the space facilitated (Mason, 2009). for the tongue at rest and during swallowing. Although expansion of the maxillary arch can The clinical perspective offered about the result in correction of a posterior crossbite and an condition of crossbite is that where there is a increase in nasal cross sectional area, the posterior crossbite and an accompanying improved breathing effects are short-lived in orofacial myofunctional disorder: (1) the airway many patients as the mucous membranes adapt and allergy status of the patient should be to changes in architecture of the nasal cavity. evaluated and treated successfully; (2) the will also require a period of crossbite should be corrected by the dental retention, which has the potential of using up a specialist; and finally, (3) the myofunctional child's cooperation early on when additional disorder should be corrected. orthodontic treatment may be required later. Current orthodontic treatment perspectives The patient with a myofunctional disorder and a regarding posterior crossbite correction posterior crossbite extending over a quadrant (or Skeletal posterior crossbites related to a narrow more) of the dental arch presents a different set maxilla or excessively wide mandible in of standards and treatment decisions than the adolescents and late mixed and early permanent normal conditions to be discussed below. Where dentition are usually treated with heavy forces to there is a posterior crossbite in a child with a open the midpalatal suture and widen the maxilla. myofunctional disorder, whether dental or By contrast, dental crossbites in these same skeletal, the crossbite is indicated for groups are usually treated by moving teeth with correction, and treatment should be lighter forces. In the early mixed dentition, accomplished prior to the initiation of however, even modest forces will lead to both myofunctional therapy to modify tongue rest dental and skeletal changes (Ngan and Fields, and functional patterns. The reason for this is 1995). For this reason, heavy-force palatal that the ‘house’ that the tongue resides in should expansion with a jackscrew appliance is reserved be normalized prior to retraining the tongue to for adolescents; that is, heavy forces and rapid function and rest properly in the physical space palatal expansion are not indicated in the primary available to it (Franklin, 2008). or early mixed dentition (Proffit and Fields, 2000).

The posterior crossbites associated with A posterior crossbite in children may appear to be myofunctional disorders have a common link to a unilateral, but closer evaluation may reveal that retained sucking habit or airway issue such as that there is a bilateral constriction of the enlarged tonsils and/or adenoids, allergic rhinitis, maxillary arch with a shift of the mandible to one nasal deformities, or other physical causes. In all side on closure (Proffit and Fields, 2000). A cases of posterior crossbite with an lateral functional shift is associated with a accompanying orofacial myofunctional canine crossbite, or some other canine disorder, patients should be evaluated and interference where a lower canine is a bit too treated (if indicated) by an ENT specialist and facial, or an upper canine a little palatal but not an allergy specialist prior to initiating therapy. quite in crossbite; perhaps end-to-end. The term Whenever possible, the crossbite should be functional shift (also called a mandibular shift) corrected prior to myofunctional therapy simply denotes, almost without exception where

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there is a shift laterally on bite closure, that it is just because the crossbite is there. There is no the canines that are causing the shift to one side valid evidence that the lack of early crossbite since they have elevated cusps. correction leads to TMJ problems later on, as previously claimed by some. Children retain a flat posterior occlusal plane up to around age 13 years. By age 16, the Curve of Crossbites caused by a functional shift of the Spee is well formed, becoming a characteristic mandible to one side during closure, however, feature of the adult dentition. During the time that should be treated as soon as they are discovered the occlusal plane in children remains flat rather and are among the few conditions recommended than curved downward toward the bicuspids as in for treatment in the primary dentition (Proffit and the adult, there is no real opportunity for children Fields, 2000). An uncorrected mandibular shift to develop biting interferences except at the can produce undesirable soft tissue growth, incisors, canines, or adult first molars. dental compensations, and teeth abrasion of primary and permanent teeth. A posterior crossbite in children with no myofunctional disorder and no functional shift is Problems of canine interferences during biting usually well tolerated and should not pose a that cause the mandible to shift laterally can be functional problem. The opportunity for a corrected easily by dental grinding/flattening problem to develop from a posterior crossbite (often referred to in dentistry as equilibration) of increases as adult posterior teeth complete their the cusps of the primary canines. Later on, when eruption back to and including the second molars. full orthodontics is indicated around age 12, a All posterior teeth have cusps that can create posterior crossbite can be corrected along with interferences. the other components of the malocclusion. Even so, orthodontic opinions remain divided about the The treatment options for moderate posterior timing of crossbite corrections. Many crossbites in children include: (1) removing the orthodontists continue to advocate for early interferences on the primary canine cusps to treatment, although there is no compelling eliminate a mandibular shift; (2) expansion of a evidence to show that arch expansion in the constricted maxillary arch; and (3) repositioning primary dentition will produce a more stable result of individual teeth to deal with intra-arch than can be achieved at a later date (Kluemper, asymmetries (Proffit and Fields, 2000). Of the Beeman & Hicks, 2000). many treatment options for posterior crossbites, the preferred appliance in a preadolescent child The orofacial myofunctional clinician will routinely is a fixed, adjustable lingual arch that requires be exposed to posterior crossbites that are little patient cooperation, such as the Quad- associated with a myofunctional disorder. What Helix®, or, alternately, the W-arch (also called a is seen in referred patients does not mirror the Porter appliance®). These appliances deliver range of crossbites seen where no myofunctional proper force levels when opened 3 to 4 mm wider disorder exists. While many dentists may than their passive width and should be adjusted express concern when there is a crossbite to this dimension prior to placement. Expansion identified at any age, early treatment is no longer should continue at a rate of 2 mm per month (1 deemed a necessity for all. Many crossbites in mm on each side) until the crossbite is slightly children, and even adults, represent conditions overcorrected. Most posterior crossbites require rather than problems. 2 to 3 months of active treatment followed by 3 months of retention (with appliance left passively In summary, the indications for treating posterior in place) for stability (Proffit and Fields, 2000). crossbites differ significantly between patients with myofunctional disorders and those without. Did you know? A posterior crossbite in children Children with myofunctional disorders are with no myofunctional disorder and without any indicated for early treatment of a posterior functional problem does not need to be treated crossbite.

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QUESTION: What should the orofacial purview of the orofacial myofunctional myologist know about anterior dental clinician and should not be included in the crossbites? evaluation process for orofacial myofunctional disorders. ANSWER: The anterior teeth in the primary dentition normally erupt vertically. If there is Dental correction is indicated for upright maxillary spacing between the primary incisors, this is incisors where there is an anterior shift of the considered a positive indication that the adult mandible, an anterior crossbite, or wear noted on teeth may have enough room to erupt into a the upper incisors. If the problem is related to normal position. Since the six anterior adult teeth upright maxillary incisors, flattening of the primary in each arch are wider than their primary canine cusps may resolve the shift, or a mild counterparts, normal eruption of adult anterior equilibration of other anterior teeth may also teeth includes not only a vertical, but a forward resolve the developing problem. For anterior path of eruption. The normal labial tilt of the crossbites, a removable maxillary appliance with incisal edges of anterior adult teeth increases the springs to tip the occlusal edges of the incisors circumference of the dental arches. In addition, forward may be indicated to correct the crossbite the increased prominence of anterior teeth in the and eliminate an anterior shift during biting. adult dentition serves to fill out the soft tissue Incorporating a biteplate in the appliance profile of the face to varying degrees as the construction insures that no damage will occur to anterior teeth provide more support for the lips. opposing teeth as the upper teeth edges are Dental crossbites can occur at any single tooth in tipped forward and past their mandibular the adult anterior dentition, or may involve counterparts. The biteplate addition to the multiple teeth. As an example, if a patient's appliance can be achieved by adding acrylic over upper incisors erupt vertically, creating an the occlusal surfaces of the primary molars; thus anterior crossbite and biting interferences, one of opening the bite during bite closure. In most two events usually follow: 1) the patient may cases, the flaring of upper anterior teeth with experience a loss of enamel from wear on the springs on a removable should involve facial surfaces of upper incisors by contacts with only a few months of treatment. the lingual surfaces of lower incisors; or 2) the patient may adapt by protruding the mandible Children with upright maxillary incisors and an slightly during biting to avoid incisor or canine anterior functional shift, an anterior crossbite, or a interferences. An anterior shift of the mandible pseudo-Class III relationship are likely to also into an even greater anterior crossbite to avoid exhibit a myofunctional disorder. As the biting interferences is often referred to as a mandible is repostured forward to avoid biting pseudo-Class III. It is not a true Class III jaw interferences, many children also are seen to relationship, but an anterior functional adaptation protrude the tongue along with the mandible. to interferences. Resting tongue posture is often interdental, which may serve as an important protective mechanism Did you know? A dentist sorts out a pseudo- for the dentition. Lip posturing problems, lip Class III from a true Class III jaw relationship with incompetence, and distorted sibilant sound cephalometric data to evaluate the relative sizes productions in speech may accompany the of maxilla and mandible. A slightly retruded posture involved. maxilla with a normal mandible can give the clinical appearance of a large mandible, leading For whatever reasons that a myofunctional to the clinical description of pseudo-prognathism. disorder may accompany an anterior crossbite, In addition, the dentist may evaluate for a an anterior shift of the mandible, or a pseudo- pseudo-Class III dental situation by manipulating Class III dental relationship, treatment is the mandible back into its full postero-superior indicated. The same rules and timing established position in the temporal fossae to determine for posterior crossbite corrections would apply for whether the most retruded position of the anterior crossbites and functional shifts. The mandible differs from that during biting. dentition and any airway issues should be Manipulating the mandible in the examination evaluated and corrected prior to the initiation process for any reason is not within the of myofunctional therapy.

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QUESTION: Why should tongue thrust modern orofacial myofunctional clinician. This therapy be recast as orofacial rest posture focus is compatible with prevailing views in dental therapy? science (Proffit, Fields and Sarver, 2006). Of course, there are other patient problems that may ANSWER: Until recently, orofacial myofunctional not fall neatly into the orofacial rest posture therapy focused on ‘tongue thrusting’ as a therapy perspective, such as the reduction or primary emphasis. It is now well known and elimination of , and post-frenectomy accepted that orofacial myofunctional disorders treatment. Nonetheless, recasting tongue thrust include thumb, lip, tongue, and finger sucking therapy as orofacial rest posture therapy more habits; a mouth-open, lips-apart posture; a clearly encompasses the work of the orofacial forward, interdental rest posture of the tongue; a myologist, especially as treatment services are forward rest position of the tongue against the marketed to the public and referral sources. maxillary incisors; a lateral, posterior interdental tongue resting posture; and thrusting of the tongue in speaking and swallowing (Mason, QUESTION: Are there mutual clinical projects 2008; 2009). These abnormal habit patterns, that orofacial myologists and orthodontists functional activities and postures can open the can undertake together that could advance dental bite beyond the normal rest position. This the field of orofacial myology? leads to a disruption of dental development in children and over-eruption of selected teeth in ANSWER: Since the specialty area of orofacial adults. myology has no university base, it rests with clinicians who provide services for orofacial Did you know? The common denominator of myofunctional disorders to engage in research orofacial myofunctional disorders is that they all that can expand the data base in orofacial result in a change in the vertical dimension, or myology and provide validation for procedures freeway space (Mason, 1988; 2005). The OMD, used and advocated by orofacial myofunctional whether digit habit or altered oral posture, causes clinicians. Many research projects can be the mandible to hinge open slightly, while also accomplished by mutual collaboration between increasing the inter-occlusal space between the orofacial myofunctional clinicians and interested jaws and teeth. Only a slight increase in resting dental referral sources. freeway space for hours per day is needed to initiate continued and unwanted vertical tooth Did you know? There are many basic questions eruption (Mason, 1988, 2009). regarding myofunctional disorders that remain unanswered. These include: Since thrusting of the tongue has been shown through research studies to represent an (1) How many individuals who tongue thrust adaptation to a developing malocclusion rather also have an anterior, interdental rest than a cause (Proffit, Fields and Sarver, 2006), posture of the tongue? This is an therapy should focus instead on the forward rest epidemiological study that has not been posture of the tongue that is linked to opening the accomplished to date. freeway space and triggering the dental changes that can result in malocclusion. Even so, a (2) Are there morphological differences tongue thrust should be corrected where there is between those with a tongue thrust and an associated cosmetic problem or an those thrusters who also have an anterior accompanying tongue-tip forward rest posture. rest posture of the tongue? This project would necessitate the availability of the Recasting therapy as orofacial rest posture lateral cephalometric films for therapy (Franklin, 2008) denotes an appropriate measurement and comparisons between understanding and appreciation of contributions groups. Such films are a routine part of from dental science that document a link between an orthodontic workup. Suggested malocclusions and oral habit patterns. measurements would include the length Establishing normal rest postures of the tongue of the mandibular ramus, comparisons of and lips should stand out as the focus of the the occlusal, palatal, and sella-nasion

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planes, and size of the adenoid mass (6) What about flaccid or hypotonic lips in (sparse, small, moderate or large). patients needing jaw surgery? Since many patients who undergo maxillary (3) Can the freeway space be closed to a osteotomy surgery had flaccid lips and lip normal level and the tongue retracted by incompetence prior to surgery, and often lip exercises only? Compare therapy consent to surgery because of this treatment protocols on two groups, one complaint, myofunctional therapy is often subjected only to lip exercises, and needed following surgery. Unfortunately, another subjected only to tongue posture surgeons are seldom aware of this retraining. Measurements of the dental problem or the benefit of myofunctional freeway space could be made before and therapy in resolving this situation. There after treatment. is an opportunity here for the orofacial myologist to offer to document lip (4) Is there a relationship between the competence or incompetence prior to vertical dimension and the length of time and following surgery and to provide required for treatment? Rank-order therapy with retained post-operative patients with tongue thrust and/or an problems of lip incompetence. anterior rest posture into groups according to the millimeters of the vertical rest position measured at the incisors, A commitment by each clinician to actively and compare treatment results according engage in clinical documentation can serve to to any vertical changes accomplished advance the data base and reputation of orofacial with your usual therapy. myofunctional therapy within the dental profession. The challenge is offered here for (5) Is there a difference in the neurological orofacial myofunctional therapists to collaborate developmental status between groups? in interdisciplinary projects that can result in Document oral diadochokinetic rates and increasing the impact and validity of this specialty movement patterns in two groups: tongue area. Are you ready to participate? thrust only versus thrust with an anterior, interdental rest posture. Clinical note: many children, especially below the age of 7 years, use a "mandibular assist" in Contact Authors: performing oral diadochokinetic tasks. In Robert M. Mason, DMD, PhD, CCC-SLP, ASHA such instances, the assessment reflects Fellow, is a speech-language pathologist and the ability of the mandible to perform practicing orthodontist in Durham, NC. He is rapid vertical movements rather than the Professor of Orthodontics in the Department of tongue. To eliminate this, instruct the Surgery at Duke University Medical Center. His patient to bite on a tongue blade inserted email address is [email protected]. between back teeth on one side of the mouth. This task provides an effective Ellen B. Role, CCC-SLP, is a speech-language way of eliminating movements of the pathologist who provides speech and orofacial mandible when evaluating the tongue. myology services in the Boston, MA area. Her email address is [email protected]

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Vig, P.S. & Cohen, B.D.S. (1979). Vertical growth of the lips: a serial cephalometric study. American Journal of Orthodontics, 75, 4, 405-415.

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