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Dental Tribune U.S. Edition

Dental Tribune U.S. Edition | October 2014A16 By Dr. Daniel Hanson, BDS Shefield, UK The majority of children today exhibit some degree of malocclusion,1,2 and it has been well documented that this is related tosoft-tissuedysfunction.3,4 Infact,itisnow so well accepted that the muscles of the tongue, lips and cheeks play a major role in tooth position and jaw development5,6 that there are contemporary pre-orthodontic clinics around the world using myofunc- tional philosophy to treat children be- tween the ages of 5 and 15 (Myobrace® Pre- Orthodontic Center). However, despite these evolutionary myofunctional treatment systems achiev- ing outstanding results, a small percent- age of cases that prove difficult to treat remains. This raises questions regarding what is causing these stubborn cases as well as how best to treat them when all ob- vious poor myofunctional habits, such as digit sucking, tongue postural issues and dysfunctional swallowing patterns, have all been addressed in the myofunctional sense. It appears that answers may be un- covered by examining the child’s airways and breathing patterns. Relevant literature explains how mouth breathing is a significant factor in the ae- tiology of malocclusion.7–12 In short, when mouthbreathingoccurs,thetonguemoves down in the mouth to allow the passage of air above it. Furthermore, an open- mouthed posture can affect the direction of growth as the muscles pulling on the jaws are affected. However, the real details of why children habitually mouth breath are not so well documented. Breathing dysfunction factors Factor 1: Tongue and head posture. Breath- ing through the mouth causes the tongue to lower and also alters the head posture. This low tongue posture then leads to re- duced maxillary growth13,14 and increases in vertical growth (Figs. 1a, b). Factor 2: The Bohr effect and cellular hy- poxia. It is important to be mindful that breathing dysfunction includes more than just mouth breathing. It also includes ha- bitual hyperventilation, which means the patient will constantly be breathing an excess of air. This will then cause the bond between haemoglobin and oxygen to be strengthened (Bohr effect), and while blood oxygen saturation can be normal, oxygen- ation at a cellular level may be reduced due to poor oxygen release from hemoglobin. As a result, cells become stressed, and this cellular hypoxia can lead to dysfunction on a cellular level (Fig. 2). My observations as a breathing educa- tor and dentist practicing myofunctional orthodontics is that in addition to malo- clussions, patients with poor breathing patternsalsotendtohavesinuscongestion, asthma, hayfever, enlarged adenoids or tonsils as well as ADD, Asperger’s and other syndromes on the autism spectrum. Factor 3: Becoming locked into a cycle of habitual hyperventilation. Patients who habitually hyperventilate become accus- tomed to breathing greater than the physi- Fig. 2: The central proposition of the Bohr effect states oxygen affinity to hemoglobin depends on absolute CO2 concentrations, and reduced CO2 values decrease oxygen delivery to body cells. Habitual hyperventilation leads to reduced arterial CO2 and, therefore, less oxygen released to cells. Hard to achieve orthodontic stability? Answer may be blowing in the wind ological norm (> 4-5L/ min at rest). It is hypoth- esised that habitual hy- perventilation causes the triggerpointatwhichthe brain detects a level of CO2 sufficient to prompt the breathing reflex to become too low, and pa- tients become sensitive to healthy CO2 levels, causing them to breathe an excess of air. Because such patients can get locked into this cycle of habitual hyperventila- tion, they may need extra help breaking the mouth-breathing habit. What can help these patients? Anincreasingnumberofdentalprofession- als are focusing on innovative techniques to help patients break their cycle of ha- bitual hyperventilation. These techniques involve a combination of breathing and airway awareness exercises intended to as- sist the patient to become accustomed to breathing smaller, healthier volumes of air. As a result, these patients learn to breathe less (retain more CO2), and more O2 is re- leased to their cells and tissues. Addition- ally, airways remain clearer, patients often become healthier, and tongue posture im- proves when mouths remain closed. These techniques are used by Myobrace Pre-Orthodontic Centers to treat the dif- ficult 5 percent of cases where the patient does not adapt to a better breathing habit using Myobrace appliances along with myofunctional and breathing activities alone. To predict which patients may require help correcting their airway dysfunction, they can be divided into three groups dur- ing treatment planning. It is important to note that the groups remain flexible. Group 1 — Unlikely to require assistance (5 percent of patients): no asthma; no Hx of ENT; no medications; no regular illness. Group2—Maypossiblyrequireassistance (90 percent of patients): previous asthma; previous ENT; medications; regular illness. Group 3 ­— Likely to require assistance (5 percent of patients): current asthma; cur- rent ENT; multiple/several medications; constant illness. Patients classified into Groups 1 and 2 are likely to change their airway dysfunction after treatment with the Myobrace Sys- tem™, which encourages correct breathing. However, patients classified into Group 3, and in some instances those in Groups 1 and 2, are likely to require additional assis- tance. Identifying habitual hyperventilators Generally, habitual hyperventilators show: • Mouth breathing, lips apart at rest. • Shoulder/upper chest breathing at rest. • Audible breathing at rest. •Medicalhistory of enlarged tonsilsand/ or adenoids, asthma, hay-fever, recurrent respiratoryinfections,snoring,teethgrind- ing or sleep apnea. • Narrow upper arch form. • Forward head/shoulder posture. Figs. 1a, b: Mouth breathing and low tongue posture cause crowding and a narrow upper arch. Images/Provided by Myofunctional Research • Venous pooling. Typically, mouth breathers will exhibit venous pooling, which occurs as a result of the inferior or- bital becoming constricted due to low lev- els of CO2, which usually has a vasodilatory effect. Additionally, this causes a reduction in N2O (found in the paranasal sinuses),15 which is also vasodilatory and mixes with air when nasal breathing is predominate. Patients with narrow maxillae can be ex- pected to have a smaller than average pter- ygomaxillary fissure. As a result of these two factors, there is less venous drainage from the inferior orbital vein, which has to pass through the narrowed pterygomaxil- lary fissure. Deoxygenated or venous blood thenpoolsbeneaththeeyes.Whenpatients habitually breathe through their mouth and have a narrow maxilla, they will show symptoms of venous pooling. Summary of factors associated with ve- nous pooling: low blood CO2 caused by habitual hyperventilation; low N2O caused by a lack of nasal breathing; reduced vaso- dilation caused by low CO2 and N2O; small pterygomaxillary fissure as a result of con- stricted maxilla; and low tongue posture. Conclusions It is clear a correctly functioning tongue acts as a natural retainer, but when a pa- tient habitually breathes through his or her mouth, the tongue is prevented from functioning in this correct way. In contrast, when the mouth remains closed and the tonguesitscorrectly,increasedorthodontic stability can be expected. Furthermore, when a patient maintains a closed-mouth posture and high-tongue posture, treatment time can be expected to lessen as forces exerted on the teeth and jaws will work favorably. Finally, it has been well-documented mouth breathing is not in the best interests of health, growth and correct development.16,17 Therefore, it is reasonable to assume encouraging correct functional breathing patterns will have a much more far-reaching effect than just correcting crooked teeth and jaws. Sim- ply fixing the teeth and jaws is potentially missingahugepieceofthepuzzleattheex- pense of possible health gains and future orthodontic stability. References available from the publisher. ORTHO INDUSTRY Clinical

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