September 1, 2010
by Jae Hyun Park, DMD, MSD, MS, PhD and Tae Weon Kim, DDS, MSD, PhD
A malocclusion characterized by an open bite is one of the most difficult conditions to treat because it results from the interaction of multiple etiologic factors.1-3 Many case reports and techniques have been reported for the orthodontic treatment of anterior open bites. Appling intrusive forces to posterior teeth is a treatment option to close anterior open bites.4,5 Nevertheless, extrusion or eruption of anterior teeth is a common method of bite closure if it is not contraindicated in the patient. Reitan6 reported that extruded teeth are less stable than intruded teeth. There might be a relapse if the extrusion of maxillary anterior teeth does not produce stability. Clear Aligners with elastics represent an easy way to treat open bite patients when a relapse occurs during the retention phase or when a minor extrusive tooth movement is necessary (extrusion of less than 2 to 3 mm) during aligner treatment.
In order to fabricate Clear Aligners to correct an open bite, impression are taken to create a working cast which is used with a plastic sheet of .030″ in thickness (Duran, Scheu-dental, Germany) and a pressure molding machine (Biostar, Scheu-dental, Germany) or a vacuum machine (Dentsply Raintree Essix, Metairie, LA).7-9 Clear Aligners made from the set-up model with ideal occlusion are connected to the opposite arch with elastics using buttons attached to the Clear Aligner (Fig. 1). Cow-Catch Clear Aligners could be used for finishing and detailing during aligner treatment or for relapse treatment cases. When the target tooth achieves its expected extrusion, it touches the surface of the Clear Aligner and no additional extrusion occurs. It has the advantage of being a fail-safe appliance. The main benefit of Cow-Catch Clear Aligners over a tooth positioner is the ability to extrude the teeth more rapidly with elastics (Figs. 2-4).
If the patient cannot open their mouth fully while wearing Cow-Catch Clear Aligners, this can be easily corrected using lingual buttons on the target teeth (Figs. 5 and 6). A modified Cow-Catch Clear Aligner can be used just as the Cow-Catch Clear Aligner. It is also more convenient and comfortable for the patient because it allows for normal function to continue (Fig. 7)
Anterior open bite is considered to be one of the most difficult treatments. Proper diagnosis and treatment planning, successful treatment, and retention have been stressed for the long-term stability of open bite treatment. There are several factors that could be related to the development of open bite. Among these are an unfavorable mandibular growth pattern, heredity, imbalances between jaw postures, digit-sucking habits, nasopharyngeal airway obstruction, tongue posture and activity and head position.3
Various treatment modalities have been proposed for the correction of anterior open bites. Nonsurgical therapies that have been used for treatment and/or retention of anterior open bite cases include multiloop edgewise archwires,10 tongue crib therapy,11 posterior bite blocks with12 and without magnets,13 and functional appliances.14 In general, stability is the most important criteria in choosing an acceptable method of treatment for patients with open bite malocclusion. Many previous studies15,16 have indicated that if open bite correction is not stable, it is because the tongue continues to be postured anteriorly which causes the bite to reopen.
When a minor extrusive tooth movement is necessary during aligner treatment or when relapse occurs during the retention phase of an open bite patient, a clear removable appliance with elastics was shown to be an effective and efficient method to treat open bite malocclusion.
After the anterior open bite treatment is finished, a 0.0175 inch twistflex wire can bonded lingually canine-to-canine as a fixed retainer on the target arch. In addition, the patient should be educated to swallow normally in order to control the tongue thrust habit. Furthermore, the new Clear Aligners were delivered as a removable appliance. In order to prevent the intrusive movement of the anterior teeth due to relapse, small projections could be added into the interproximal areas of the target teeth using the Clear Aligner Plier (IV-Tech, South Korea). However, a removable appliance with a tongue crib is recommended if the tongue thrust habit persists after treatment.
A potential disadvantage of this type of appliance is that it is highly dependent on patient compliance.17 The aligner should be worn with elastics at least 17 hours per day including sleeping time,7-9 yet, current data suggests that this rarely is an issue.17,18 During aligner treatment when detailing is necessary along with extrusion, the Cow-Catch Clear Aligner is an excellent choice. Decent interdigitation is achieved within 6 to 8 weeks of treatment. If a patient is concerned about opening their mouth or speaking while wearing Cow-Catch Clear Aligners, modified Cow-Catch Clear Aligners could be used as an alternative (Fig. 8).
If a patient wears the clear removable appliance with elastics for a recommended period of time, the tooth movement is efficient. The aesthetics is excellent with the aligner since it is hardly visible. This can be a definite psychological advantage to teen-agers and adults alike. The Clear Aligner with elastics can be used as an effective alternative in certain open bite cases for those who refuse to wear conventional fixed appliances. OH
Jae Hyun Park, DMD, MSD, MS, PhD, Associate Professor and Chair, Postgraduate Orthodontic Program, Arizona School of Dentistry & Oral Health, A. T. Still University, Mesa, AZ and International Scholar, the Graduate School of Dentistry, Kyung Hee University, Seoul, Korea.
Tae Weon Kim, DDS, MSD, PhD, President of Korean Society of Lingual Orthodontics.
Oral Health welcomes this original article.
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