14: Posterior crossbite

14 Posterior crossbite

Summary

Kirsten is 7. She presents with a crossbite of the right buccal segments (Fig. 14.1). What will be your assessment and management options for this problem?

image

Fig. 14.1 Anterior occlusion at presentation.

History

Complaint

Kirsten’s mother is concerned about the way her daughter’s teeth bite together. She has noticed that Kirsten’s jaw moves to one side as she closes her mouth. This makes her face appear crooked, a further cause of anxiety for her mother.

History of complaint

Kirsten used to suck her thumb until 5 months ago when image started to erupt. Her mother has become more aware of her daughter’s ‘deviated bite’ in the past year and wondered if the thumb-sucking habit could have contributed to the problem.

Medical history

Kirsten is fit and well.

Family history

There is no family history of facial asymmetry.

Examination

Extraoral

Kirsten has a mild Class III skeletal pattern with slightly increased FMPA; the chin point is displaced slightly to the right. The lips are incompetent but habitually held together. There is a tongue to lower lip swallowing pattern. There is no masticatory muscle tenderness, temporomandibular joint tenderness or crepitus, and mouth opening is not restricted.

image What other feature would you check for, bearing in mind the history? Explain why

It is important to check if there is mandibular displacement on closure as this would indicate that the facial asymmetry is more an apparent than a true skeletal asymmetry. For the former, orthodontic correction of an associated crossbite should be straightforward but for the latter further investigations would be required to determine if the asymmetry is progressive and more complex treatment would be required to address the facial and occlusal problems.

Early correction of a crossbite with a mandibular displacement is indicated to allow the occlusion to develop in an undisplaced position. It is likely also to reduce the possibility of development of temporomandibular joint dysfunction syndrome, which may occur in susceptible individuals in whom this occlusal discrepancy exists.

An anterolateral mandibular displacement on closurewas detected on image with an associated 3 mm shift between retruded contact position (RCP) and intercuspal position (ICP).

Key point

Early correction of a posterior crossbite with associated mandibular displacement is advisable.

Intraoral

image What features are evident on the intraoral views (Figs 14.1 and 14.2)?

Mild marginal gingival erythema related to the erupting permanent incisors but otherwise the soft tissues appear healthy. There is no caries visible.
6edcb1 are present in both upper quadrants and in the lower right quadrant; 12cde6 are present in the lower left quadrant.
Spacing of the upper and lower incisors with distopalatal rotation of image.
Class III incisor relationship.
Anterior open bite.
Lower centreline shift to the right.
Half-unit Class II right molar relationship with buccal crossbite of the right buccal segments (note palatal inclination of the teeth).
Class III left molar relationship.
image

Fig. 14.2 (A) Right buccal occlusion.

image

Fig. 14.2 (B) Left buccal occlusion.

image How would you assess the centrelines?

The upper and lower centrelines should be coincident with each other and with the midline of the face. Both of these aspects should be assessed, the latter by first looking at the patient anteriorly and then down on the face from above. With study models alone, it is not possible to determine the relation of the dental midlines to the facial midline.

In this case, the lower centreline is displaced to the right by about half the width of a lower incisor.

image What are the possible causes of a lower centreline shift?

The/>

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Jan 2, 2015 | Posted by in Orthodontics | Comments Off on 14: Posterior crossbite

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