15 Bilateral crossbite
Jean has just turned 12. She presents with bilateral buccal crossbites (Fig. 15.1). What are the possible causes and how could it be managed?
Her mother says that Jean’s ‘baby’ teeth had the same appearance and she also has a similar appearance of her upper teeth to her daughter. Jean’s teeth erupted in the position they are in at present. There is no history of trauma to her upper jaw and birth was normal.
Jean is asthmatic and uses a salbutamol (Ventolin) inhaler. She is prone to upper respiratory tract infections and is unable to breathe through her nose. Her mother reports that she snores and is prone to day-time drowsiness, which her teachers have noticed. Otherwise she is well. Her mother wonders if the narrow appearance of Jean’s upper teeth is related in any way to her mouth breathing and snoring. She is keen to know if Jean’s mouth breathing and snoring could be improved by any brace treatment.
Compulsive mouth breathing, due to inability to breathe through the nose, may contribute to an altered head posture and low tongue position; this may lead to unopposed action of buccinator musculature and bilateral narrowing of the upper arch creating bilateral buccal crossbites.
Inability to breathe through the nose is also linked with snoring, which is associated with sleep apnoea, a major cause of day-time drowsiness. Prolonged inflammation of the nasal mucosa associated with allergies (in Jean’s case there is a history of asthma) or chronic infection (she is prone to upper respiratory tract infections) could produce some degree of nasal obstruction and lead to mouth breathing. The normally large pharyngeal tonsils or adenoids in children may also contribute.
The appearance of the teeth on presentation is shown in Figures 15.1 and 15.2. Describe what you see
|Bilateral buccal crossbite||Possible causes|
|Skeletal||Mismatch in relative widths of arches or anteroposterior discrepancy (commonly associated with Class III malocclusion)|
|Soft tissues||Possible role of adenoids/tonsils (see text)|
|Low tongue position possibly due to altered head posture associated with mouth breathing|
|Scar tissue of cleft repair restraining growth in upper arch width|
It would be important to ascertain if there is an associated mandibular displacement, although this is rare with bilateral crossbites. It is more usual to have a mandibular displacement associated with a unilateral buccal crossbite.
A dental panoramic tomogram would be useful to determine the presence, position and form of unerupted third molars. A lateral cephalometric radiograph will also be required (to ascertain the angulation of the upper and lower incisors to their respective dental bases).
Relative to mean values for Caucasians, SNA is normal; SNB is slightly increased; ANB (SNA − SNB) = 2°, indicating a Class I skeletal pattern; MMPA is slightly increased, 1 to maxillary plane is increased, so upper incisors are slightly proclined; to mandibular plane is normal; interincisal angle is slightly increased; facial % is slightly increased.
Class I malocclusion on a Class I skeletal pattern with slightly increased FMPA and no facial symmetry. Generalized marginal gingivitis. Moderate lower labial segment crowding: mild upper labial segment crowding with 2’s in crossbite; upper and lower centreline shifts. Molar relationship Class I on right; Class III on left with bilateral buccal crossbite affecting .
Oral hygiene instruction by hygienist. Provided the marginal gingivitis is corrected then proceed to correction of the bilateral buccal crossbite (the need for extractions for relief of crowding and centreline correction should be reviewed following crossbite correction).
The options are given in Table 15.2. In view of the severity of the crossbite and the desire to simultaneously, if possible, improve nasal breathing, rapid maxillary expansion (RME) would be the preferred choice of treatment.
|Accept and monitor||Patient not keen for correction.||Not an option here as Jean is keen for correction|
|Part of underlying skeletal III problem which is likely to worsen with mandibular growth, especially in males|
|Removable appliance with midline screw or heavy midline spring||Primary/early mixed dentition||Rate of expansion must be quite slow and force employed low: otherwise retention of appliance compromised by higher expansion forces|
|Compliance with wear and activation may be problematic|
|Not cost-effective as often lengthy time required to produce desired expansion|
|Quadhelix||Preferred approach in early mixed dentition||Made of 1 mm stainless steel wire attached to bands cemented to molar tooth on each side|
|3–5 mm maxillary expansion required (mainly dental but some skeletal expansion)||Delivers few hundred grams of force|
|Teeth preferably tipped palatally but molar inclination may be adjusted with fixed appliances later||Produces efficient slow expansion|
|May derotate />|