17: Prominent chin and TMJDS

17 Prominent chin and TMJDS

Summary

Jocelyn, aged 23, is referred by her general dental practitioner because of her prominent chin (Fig. 17.1) and pain in her left temporomandibular joint (TMJ). What are the causes and how would you manage these problems?

image

Fig. 17.1 Profile at presentation.

History

Complaint

Jocelyn’s main concern is that she does not like the prominent appearance of her chin and her upper teeth biting inside her lower teeth. She has pain in her left jaw joint and has some difficulty chewing. She is also aware that she has a lisp, which she dislikes.

History of complaint

Jocelyn has been more aware of her prominent chin and her bite since she was in her last year at school. After consultation with an orthodontist at age 12, she had two upper teeth removed to provide space for the upper eye teeth (she had both lower first permanent molars extracted at age 8 because of decay.) She did not wear any braces on her teeth. She was advised to wait until she was in her late teens to have the bite of her front teeth reassessed. In the past 6 months she has become quite self-conscious about her facial appearance, although she feels that her chin does not appear to have become more prominent in the past 4 years.

image What questions would you ask about the temporomandibular joint pain?

When and how the pain started.
Type and duration of pain.
Frequency.
Is it localized? Site of radiation.
Associated symptoms, e.g. muscle pain, click, jaw locking, trismus.
Aggravating factors, e.g. stress.
Any habits, e.g. nail-biting, bruxism, pen-chewing.
Relieving factors, e.g. heat, analgesics (type and amount).

The pain started suddenly when Jocelyn was preparing for examinations in her first year at university. She has had intermittent discomfort in her left jaw joint since then but it has been of a mild nature. The discomfort is an ache that is principally in the left jaw joint area but radiates to the jaw muscles on that side. It does not keep her awake at night but she feels it is worse in the morning. Typically it lasts for a few hours and then disappears. It tends to return when Jocelyn is stressed by work. She is aware of grinding her teeth when stressed. She does not engage in chewing pencils or pens or nail-biting. She feels that in the past year the pain has recurred more frequently and has become worse. Chewing hard food or opening her mouth too wide makes the pain worse; one or two paracetamol tablets usually relieves the ache. Jocelyn is also aware that she has a jaw click.

Medical history

Jocelyn is fit and well.

Dental history

Jocelyn is a regular attender at her general dental practitioner and brushes twice daily.

Family history

Jocelyn’s sister also has a prominent chin, but not as marked as hers, and her sister’s bite was corrected with fixed braces.

Examination

Extraoral examination

image What do you observe from Jocelyn’s profile view (Fig. 17.1)?

Class III skeletal pattern with average FMPA. Competent lips.

image Based on the history, what other aspects would you assess extraorally?

Temporomandibular joints. Opening and lateral mandibular movements should be assessed by first observing the patient from in front and second by palpation of the condylar heads while listening for the presence of crepitus or a joint click. As symptoms are present, the masticatory muscles should also be palpated. A left TMJ click and left masseteric tenderness were detected.
Mandibular path of closure. The path of closure from rest position to maximum interdigitation should be assessed, noting any anterior or lateral mandibular displacement produced by a premature contact.

In this case, there is an anterior mandibular displacement on closure on contact of image (centric relation to occlusion shift of ~3 mm).

Intraoral examination

The intraoral views are shown in Figure 17.2.

image

Fig. 17.2 (A) Right buccal occlusion.

image

Fig. 17.2 (B) Anterior occlusion.

image

Fig. 17.2 (C) Left buccal occlusion.

image What do you see?

Gingival tissues appear healthy; gingival recession related to image.
Oral hygiene appears overall good apart from slight plaque deposit on image
image are visible.
No obvious caries.
Very mild lower incisor crowding with spacing between the image and image.
Very mild upper arch crowding with slight mesiolabial rotations of image.
Class III incisor relationship with reverse overjet (measured 4 mm clinically), reduced overbite and coincident dental centrelines.
Class I canine relationship bilaterally.
Buccal crossbite affecting image.

image What is the most likely cause of the considerable spacing in the lower premolar areas with image drifted into contact with image?

Early removal of image in an uncrowded arch is the most likely explanation for the spacing. An uncrowded lower arch is common in Class III malocclusion.

image What occlusal features may predispose to temporomandibular joint dysfunction syndrome?

Crossbites, Class III malocclusion and anterior open bite have been shown to have a significant association with temporomandibular joint dysfunction syndrome (TMJDS) in some studies while others have found no link between signs and symptoms of TMJDS and mandibular displacement. The aetiology of TMJDS is multifactorial with the implicated involvement of psychological, traumatic and occlusal elements. The most salient factor is probably stress, which may transmit its effect by a parafunctional habit, stemming perhaps from a displacing occlusal contact in susceptible individuals. In this case, a displacement exists on image on closure. There are also anterior and posterior crossbites present.

image Why was Jocelyn advised to wait until her late teens for reassessment?

In a Class III malocclusion, the amount of reverse overjet tends to increase with forward mandibular growth during teenage years. Waiting until mandibular growth is essentially completed, which is generally about 17 years in girls and 19 years in boys, has three advantages. First, it allows treatment planning to be undertaken with reasonably stable facial and occlusal characteristics. Second, if treatment is undertaken, it safeguards against relapse due to further growth. Third, the magnitude of occlusal change due to mandibular growth influences whether treatment can be undertaken by orthodontic means alone or whether a combined surgical-orthodontic approach is necessary. Orthodontic treatment involves inducing dentoalveolar compensation for the underlying skeletal pattern, but if unsuccessful due to continued adverse mandibular growth the compensation would need to be undone as part of pre-surgical orthodontics. This may involve opening up lower premolar extraction spaces. Hence the decision to treat a Class III mal/>

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Jan 2, 2015 | Posted by in Orthodontics | Comments Off on 17: Prominent chin and TMJDS

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