dentofacial assessment of orthognathic patient part 1

Dentofacial assessment of orthognathic patient

Part 1Prof Dr Maher Fouda

Faculty of Dentistry, Mansoura University . Mansoura, Egypt

Assessment of the orthognathic patient should be carried out systematically to ensure that a complete picture of the presenting dentofacial dysmorphology is assembled .

A pro-forma may be helpful in guiding the clinician through the assessment in planned sequence and documenting the findings in a structured manner.

General assessmentBecause orthognathic surgery is largely elective in nature, the patient’s concerns are the main reason for pursuing treatment and must be carefully elicited from the outset.

Whilst most patients will describe one or more clear problems, some will be more vague and will have to be probed more thoroughly to establish exactly what they are seeking to derive from treatment.

General assessment

General assessment

In general, patients’ concerns fall into the following categories: 1. Functional problems: a. Difficulty with biting and chewing.

General assessment

b. Discomfort due to the malocclusion: i. Palatal or gingival soft tissue trauma (e.g. deep overbite). ii. Dental trauma (e.g. limited tooth contact). c. Temporo-mandibular joint dysfunction. d. Speech difficulties

Functional problems:

General assessment

2. Aesthetic problems: a. Facial appearance. b. Dental appearance. c. Gingival display.

If the psychologist can be present on the clinic when the patient is being examined, this is valuable in helping the patient to express their concerns and the clinicians to understand them

General assessment

Medical, dental and social history

As with any surgical or dental patient, a full medical history should be taken prior to clinical examination

if the patient reports any significant illnesses at initial assessment it is prudent to contact the General Medical Practitioner or Consultant Specialist for clarification or further investigation .

Medical, dental and social history

It is important to establish the patient’s level of dental motivation and ensure that they will have the ongoing support of a General Dental Practitioner for the duration of their treatment.

If there is a history of dental anxiety it is important to make sure that the patient will be able to cope with the challenges of surgical orthodontic treatment

Medical, dental and social history

Medical, dental and social history

A patient’s social history should at least include questioning about home circumstances, smoking and alcohol consumption.

It is also important to know about any history of mental health problems, but specialist questioning in this area is most appropriately undertaken at the psychology interview.

History of dentofacial dysmorphologyA history should be taken from the patient regarding the development of their dentofacial problems. This should include the following: 1. Congenital anomalies (e.g. growth abnormalities, condylar hypoplasia or agenesis, hemi-facial microsomia).

2. Familial traits (i.e. other family members with facial dysmorphology, such as class III jaw relationship).

History of dentofacial dysmorphology

History of dentofacial dysmorphology

3. Acquired anomalies: a. Traumatic (e.g. TMJ trauma, before and after cessation of growth). b. Pathology (e.g. pituitary adenoma).

History of dentofacial dysmorphology

4. Racial characteristics: a. Anterior bi-maxillary protrusion (Black African, Chinese). b. Zygomatico-maxillary hypoplasia (Asian).

History of dentofacial dysmorphologyIt is important to recognise progressive facial dysmorphology, which most commonly manifests as follows: 1. Gradual increase in anterior open bite (e.g. idiopathic condylar resorption). 2. Progressive late mandibular growth (e.g. pituitary adenoma)

3. Progressive mandibular asymmetry: a. Unilateral condylar hyperplasia. b. Unilateral condylar resorption. c. Unilateral condylar tumour (e.g. osteochondroma). d. Hemi-mandibular elongation. e. Hemi-mandibular hypertrophy.

History of dentofacial dysmorphology

It is important to elicit the most accurate possible history regarding the progress of these conditions. Previous family or school photographs, if available, can be extremely helpful .

History of dentofacial dysmorphology

Stature and body form

The patient’s height and general body shape should be noted early on in the assessment, since orthognathic treatment should be aimed at delivering facial proportions that are in keeping with the patient’s build.

A tall, lean patient is unlikely to suit a disproportionately reduced lower anterior face height and a short, broad patient is unlikely to suit an increased lower anterior face height.

Stature and body form

Stature and body formSimilarly, a patient’s stature may influence the surgical plan in the anteroposterior plane. For example, in certain class III patients, standing height might play a part in deciding whether surgical correction would be by means of a maxillary advancement or a mandibular setback

Where a patient is clearly overweight this can be a contra-indication for elective orthognathic surgery. In such cases, the patient may be required to reduce their weight before they can be considered for treatment. The Body Mass Index (BMI) is helpful as a guide.

Stature and body form

• The BMI is computed by dividing the person’sweight in kilograms (kg) by their height in meterssquared (m2).

• In men, obesity is defined as a BMI of 27.8; forwomen, obesity is a BMI of 27.3.

Facial assessment

Lateral view The patient should be seated comfortably with their back in an upright position and asked to adopt their natural head posture (NHP), in which they are generally viewed in everyday life. This can be made easier by asking them to look in a mirror mounted straight ahead of them.

The patient’s head posture can affect theclinical impression of theirantero-posterior jaw relationship

Lateral view

The patient’s head posture canaffect the clinicalimpression oftheir antero-posterior jawrelationship

The alternative method of positioning the Frankfort Plane (FP) parallel to the floor may place them in an artificial position, since this not a reliable horizontal reference plane in patients with significant facial skeletal discrepancies. It has been shown that NHP is more reliable than FP for orientation of the head. Inappropriate head positioning can result in a false perception of the antero-posterior jaw relationship

Habitual tilting of the head to the left or right side should be avoided. However, for patients that have a condition that produces involuntary tilting, such as tortocollis (due to shortening of one of the sternomastoid muscles), this should be accepted as their normal posture, as it is unlikely to improve as a result of surgery.

It is important for the peri-oral soft tissues to be relaxed, particularly in patients with increased vertical proportions, who may have incompetent lips and will tend to habitually posture them together through mentalis muscle hyper-activity.

Viewing the face from the lateral aspect allows the assessment of: • Jaw relationship and facial convexity. • Forehead. • Infra-orbital rims. • Nose. • Para-nasal region. • Upper lip. • Lower lip and chin. • Lower lip to sub-mental plane angle. • Mandibular plane angle

Jaw relationship and facial convexity: The left and right sides of the head should be examined separately, since characteristic differences will be detected in asymmetric faces

Or Soft tissue subspinale is the point of greatest concavity in the midline of the upper lip between subnasale (Sn) and labrale superius (Ls) .

changes of facial convexity (FC) in Class III patients (c = presurgery, d = postsurgery) revealed high significance.

The relative antero-posterior positions of the maxilla and mandible, as well as the convexity of the profile, can be assessed subjectively by looking at the patient’s profile in natural head position. The facial convexity can also be measured objectively on a profile photograph, including or excluding the nose, as illustrated in Figure 2.2a.

A class II jaw discrepancy will generally manifest as a convex profile (Figure 2.2b), while a class III profile will be concave (Figure 2.2c)

In some class III cases, the drape of the upper lip can mask the underlying maxillary deficiency to large extent and present a deceptively normal soft tissue profile .

This is most likely in high angle cases where there is a degree of bi-maxillary retrusion owing to the downward and backward position of the chin

In class II cases, maxillary protrusion is uncommon, relative to the patient’s racial norm, but it is not uncommon to see bi-maxillary retrusion, particularly in patients with long facial types.

In class III cases, maxillary deficiency is common but again, in high angle cases, bimaxillary retrusion with retrogeniacan be present

In such cases, the telltale signs of maxillary deficiency will be present, such as para-nasal hollowing (Figure 2.3)

ForeheadIt is important to note the position and shape of the forehead, since it is one of the parts of the face that will remain completely unchanged by orthognathic surgery. If frontal bossing is present or the forehead is flat, this should be taken into account when assessing the jaw positions and the effects of surgery, such that harmonious facial balance will be achieved.

The shape of the nasal dorsum and the angle of the nasal tip may be affected by maxillary osteotomy and it should be carefully noted whether or not such changes are likely to be favourable. For example, a patient with maxillary deficiency who already has an up-turned nasal tip is likely to experience a worsening of this feature with a Le Fort 1 advancement osteotomy.

Nose

On the other hand, a patient with a long facial type and a down-turned nasal tip may well

experience an improvement in their nasal profile as a result of Le Fort 1 impaction osteotomy. In addition, an assessment of the prominence of the nose in relation to the forehead and chin is essential, in diagnosing the jaw discrepancy and planning the required surgical correction (Figure 2.2).

The contour of the skin overlying the area just lateral to the alar base can be seen from the side view. A lack of bony support for the soft tissues in this region will produce a depression described as para-nasal hollowing, which is indicative of low level antero-posterior maxillary deficiency (Figure 2.3). Although most commonly associated with class III jaw discrepancies, it can also be present in class II cases with bi-maxillary retrusion.

Para-nasal region

Upper lip

It is important to assess the form and angle of the upper lip. The naso-labial angle is often taken as an indication of the position of the underlying maxilla and incisors. However, it is prone to variation according to the slope of the columella and the curvature of the upper lip and the angle can be measured in a number of different ways

Upper lip. A patient with maxillary deficiency will tend to show an increased naso-labial angle .

Upper lipHowever, an unusually short upper lip may be more furled than average, or the columella may be down turned, giving rise to an acute angular measurement, even in the presence of maxillary deficiency .

Conversly some patients present with a deficient maxilla but the proclined upper anterior teeth support the upper lip.