4.1 History and orthodontic pretreatment

The patient presented to the orthodontist with the chief complaint that the maxillary canines were too far vestibular.

The physician made the following findings at the initial presentation:

Face (Fig 4-1)

• excessive gingival display

• clearly negative lip step

• deep labiomental fold

• enlarged chin prominence

• short submental region

• large mandibulocervical angle.

Intraoral findings (Fig 4-2)

• bite anomaly class II/2

• deep bite

• crowding of the maxillary anterior teeth

• vestibular position of maxillary canines

• transverse dental arch discrepancy with narrow maxillary base.

Radiographic findings (Fig 4-3)

• mandibular retrognathia

• transverse narrow maxilla.

Due to nocturnal bruxism, the patient was initially fitted with a bite splint.

The maxillary canines were aligned as part of the preoperative molding of the dental arches, and the patient was then referred to maxillofacial surgery for planning of the maxillomandibular realignment osteotomy.

4.1.1 Clinical diagnostics in preparation for oral surgery planning

Three appointments were made to plan the surgical correction of the malocclusion.

1st appointment

Clinical diagnostics and correction planning consisting of the following steps:

1. Radiographic diagnostics (panoramic radiography).

2. Clinical findings with standard facial and intraoral photography.

3. Clinical operation planning.

4. Further diagnostics with impression taking of maxilla and mandible for creation of dental casts, bite taking in arbitrarily centric condylar position, and determination of maxillary position by facebow application.

2nd appointment

5. Skull CT or DVT with relaxation splint in situ to check the temporomandibular joint position and as planning CT/DVT.

6. Lateral cephalometric radiograph with relaxation split in situ.

7. Cephalometric measurement of the lateral cephalometric radiograph with final operation planning.

3rd appointment

8. Check of the operative splints, if necessary with adjustment.

4.1.2 Maxillofacial planning of the surgical correction of the malocclusion

In order to plan the operation clinically, the initial findings were collected preoperatively. From these, the consequences for clinical operation planning were derived (above steps 1 to 3).

This was followed by further diagnostics with cephalometric analysis and synthesis of these with clinical operation planning (steps 4 to 7).

4.2 General information and medical history

The patient information and medical history was collected (Fig 4-4).

4.2.1 Diagnostics

A radiographic check (Fig 4-5) was performed for apical rarefaction and pathologies in the temporomandibular joints or in the maxillary sinuses to assess the risk of possible increased perioperative wound infections. This also serves as an overview of the position of the mandibular canal and the length of the tooth roots for positioning the subsequent osteotomies.

Findings

No pathologies or surgery-relevant features were seen here.

Consequence

None.

4.2.1 The patient’s reason for treatment

Findings

The vestibular position of the maxillary canines, which is favored by the narrow maxilla, had already been corrected orthodontically.

Consequence

The transversely narrow maxillary base will be surgically widened.

4.2.2 General anamnesis

Findings

The patient had no previous diseases or allergies relevant to surgery.

Consequence

None.

4.3 Clinical examination

The extraoral photographic documentation of the patient followed according to the described standard procedure (see Chapter 1).

4.3.1 Facial examination: frontal view

Figure 4-6 shows the preoperative setup documentation.

Habitual head posture

Findings

Habitually, the patient shows a slight right-sided and caudal tilt of the head (Fig 4-7a).

Consequence

Referral to orthopedist with question of functional cause.

Proportions and symmetries

Proportions/facial third

Measurement of the facial thirds (upper, middle, and lower face):

• Upper face = hairline to glabella

• Midface = glabella to anterior nasal spine

• Lower face = anterior nasal spine to underside of the chin/ menton.

In a harmonious face, the three proportions are ⅓ to ⅓ to ⅓.

Findings

In this case, the measurements were 60/63/58 cm (Fig 4-7b). The lower third of the face was thus somewhat too short (= short lf) compared to the other parts, most likely due to the deep bite.

Consequence

The upper face cannot be changed with a maxillomandibular realignment osteotomy. The vertical of the midface changes due to cranialization or caudalization of the maxilla and thus the anterior nasal spine; here, the amount of visible maxillary incisors has priority.

In this case, the lower face will be lengthened vertically by removing the deep bite. For harmonization, a chin correction with vertical lengthening can also be performed if required.

Symmetry

Findings

The right eye appears to be lower than the left (Fig 4-7). Since a perpendicular is dropped on the interpupillary line for reconstruction of the facial midline (as described below), it is essential for subsequent planning in the event of visible deviations to perform a review of the underlying structures (orbits, bulbi, etc) and determine whether this important line may be used as a reference for surgical planning.

Here, the first step was to exclude an orbital depression by means of the later preparatory computed tomography.

The CT findings were:

• Symmetrical bony orbits (Fig 4-8a)

• Minimal right midface hypoplasia. The facial skull appears slightly more hypoplastic on the right side than on the left (Fig 4-8b)

• Right lateral inclination of the head in comparison to the cervical spine (Fig 4-8c); the dens axis is laterally displaced to the left in the atlantoaxial joint (Fig 4-8d)

• In addition, there is a slight asymmetry of the skull in the region of the parietal bone and the occipital bone on the right side (Fig 4-8e)

• The apparent asymmetry of the orbits comes from a slight rightward tilt of the head (Figs 4-7c and 4-8c).

An orthopedic consultation was performed for further clarification of the head slope:

• History of occasional muscle tension in the neck

• Joint blockage upper cervical joint C0/C1 left with atlas irritation and paracervical muscle hard tension with restriction of end rotation and lateral inclination

• Shoulder advancement with hyperextension of the cervical and lumbar spine, head forward tilt relative to the body plumb line

• Summary: Cause of head side tilt most likely functional and due to vertebral joint blockages.

Consequence

The bony orbits were symmetrical. The presumed bulbous depression was mainly due to soft tissue and will be clarified in the next step.

The head misalignment was functional and could be treated physiotherapeutically. It was therefore not necessary to consider it in the correction planning of the malocclusion.

Center lines

A frontal photo showing the anterior teeth of the maxilla and mandible was used to measure the center lines accurately (see Fig 4-9a).

To check whether the photo can be used for reconstruction of the facial midline, the following points must be ensured:

• Was the photo taken correctly from the front? This can be checked, for example, by making sure that both ears/tragi are visible in equal parts (unless the patient has differing protrusion of the ears). In addition, the head must not be turned to the side, or otherwise the reconstructed facial midline will be shifted to the opposite side. A mere slight sideways tilt of the head does not lead to an error in the midline determination. The check here is whether the determined facial midline passes through the center of the glabella/nasal root.

• Is the patient looking straight at the camera? If the patient is looking to the side, the photo cannot be used. If there is a side-differentiated squint, the reconstructed facial midline must be adjusted and matched with the patient’s wishes preoperatively.

• Is one eye lower than the other? For example, in case of hemifacial microsomia or after fractures (see above). In this case, the adjustment of the center of the maxilla may also have to be adjusted in consultation with the patient.

After drawing in the interpupillary line (= horizontal red line, eg due to the light reflections from the flash), the distance between the pupils (= yellow) is measured and the perpendicular is dropped in the middle onto the interpupillary line. This is the facial midline. Alternatively, in the case of a side-differentiated strabismus, the center of the distance between the two median canthi (= white) can be used as the center of the face.

Now the deviations of the tip of the nose, the anterior nasal spine, the maxilla (= approximal contact of maxillary central incisors), mandible (= approximal contact of mandibular central incisors), and chin are measured.

Findings

In the present patient (Figs 4-9a and 4-9b), compared to the facial midline:

• Nasal tip and anterior nasal spine were 1 mm to the right

• Maxillary midline was shifted 2 mm to the right

• Mandibular midline was shifted 3 mm to the right

• Chin tip was 4 mm to the right.

Consequence

Unless the patient requests a secondary rhinoplasty, the maxilla, mandible, and chin are not placed in the center of the face, but centered to the tip of the nose and anterior nasal spine. A discrepancy of up to 2 mm to the facial midline is usually tolerated by patients, as this is not noticed in everyday life. A discrepancy of the maxillary midline to the nasal tip is more noticeable.

The mandibular midline is adjusted by the bilateral sagittal split with achievement of a Class I dentition. In order to be able to center the chin tip, an additional chin correction must be performed after adjusting the center of the mandible. This must be discussed with the patient before planning surgery.

Midface

Findings

A right-sided scleral show was noticeable (Fig 4-10), which can either be due to midface hypoplasia, but then usually occurs bilaterally, or due to a retracted lower eyelid on the right side.

CT showed centrally located bulbi oculi in symmetrical bony orbits (see Fig 4-8a). There was only a minimal bony midface hypoplasia on the right side compared to the left side (Fig 4-11, and see Fig 4-8b). In the clinical photographs of the patient from below, a minimal difference in the right and left cheek contour can be seen (Fig 4-12).

The palpebral fissures were the same size on both sides, but the right palpebral fissure exposes a more caudal part of the eye than the left one because the patient has a slight ptosis of the right upper eyelid (Fig 4-13).

The ophthalmology consultation revealed the following:

• Anamnestic: myopia, no complaints, on photos before 2009 there was already slight retraction of the lower eyelid on the right side

• Slight lower eyelid retraction right

• No Horner syndrome

• No measurable exophthalmos by Hertel test

• Clinical eyelid fissure 12 mm on the right and 11 mm on the left when looking straight ahead, same fissure width when looking up and down.

The scleral show on the right is most likely a result of lower eyelid retraction.

The nostrils are slightly asymmetrical.

Consequence

No operational consequence for maxillomandibular osteotomy.

Lower face

Findings

The preoperative documentation of the lower face is shownin Fig 4-14a. Analysis of the lower face revealed the following:

• Lip closure insufficiency of 6 mm with relaxed lips (Fig 4-14b)

• Visible maxillary incisor length: 5 mm (Fig 4-14b)

• Visible mandibular anterior teeth: 2 mm (Fig 4-14c).

Consequence:

To set the desired maxillary anterior view of 4 mm, the maxilla was cranialized 1 mm. The correction of the calculated remaining lip closure insufficiency of 4 mm had to be made from the mandible.

Stay updated, free dental videos. Join our Telegram channel

Join