This case report evaluates three-dimensional bone development in a male and Caucasian growing patient, with Angle class III malocclusion and mandibular deviation to the right. The orthopedic - orthodontic management had a duration of 3.8 years divided into two phases: the first phase with the RPE and the second phase with the FR-3. The patient was 8 y.o. at the beginning of therapy, and he was 12 y.o. at the end. The initial CBCT was acquired at the beginning and the final one at the end of the treatment.
A therapeutic program can be planned for the mandibular asymmetry management after a clinical and radiological diagnosis.
The clinical diagnosis is the first step in orthodontic practice. No systemic pathologies or maxillofacial disorders were found in the medical history; the clinical examination reveals an Angle class III malocclusion, an anterior crossbite and a mandibular midline deviated to the right. The deviation of the lower midline was measured using a ruler and the value was 4 mm.
The radiological diagnosis is the second step: all measurements were performed on the CBCT. The analysis reveals a class I skeletal profile [8] (ANB: +0.9°), mesocephalic [9] (SN - GoGn: 30.1 °), hypodivergent growth pattern [10] (FH - GoGn: 13.6 °), moderate right-shift of the menton (4.2 mm) [11].
All CBCT images were obtained with the Planmeca Promax® 3D MID unit (Planmeca Oy, Helsinki, Finland) according to the low-dose protocol with large FOV, normal resolution quality images, 80 kVp, 5 mA and acquisition time of 15 s resulted in a value of effective dose of 35 microSievert (µSv) [12].
The three-dimensional graphic rendering software used for the cephalometric measurements was Dolphin Imaging 11.95 Premium (Patterson Technology, Chatsworth, CA). The software processes the 3D-CT scan images in 2D-DICOM files (Digital Imaging and Communications in Medicine).
Patient’s CBCT was performed with the head oriented according to the NHP; the patient was in a sitting position with the back perpendicular to the floor, as much as possible. The head was stabilized with ear rods in the external auditory meatus. The patient was instructed to look into their own eyes in a mirror, 1.5 m in front of them to obtain NHP. The NHP is a physiological and reproducible posture defined for morphological analysis as described in the orthodontic and anthropological literature. [13]
The 3D image of the cranium was oriented in the Dolphin software according to NHP posture, before taking cephalometric measurements.
The NHP orientation was carried out by the widgets present in Dolphin; hard and soft tissue views were checked for orientation in the software by visualizing head from front, right, and left sides. In the NHP there are 3 reference planes (Fig. 1), perpendicular to each other, which are identified on the software for the patient's cephalometric measurements.
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The transverse plane coincides with the Frankfurt plane (FH), a plane passing through two points: Orbital (Or) and Porion (Po);
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The sagittal plane coincides with the mid-sagittal plane (MSP), a plane perpendicular to the plane FH and passing through two points: Crista galli (Cg) and Basion (Ba);
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The coronal plane coincides with the anteroposterior (PO) plane, perpendicular to the FH and MSP, passing through the right and left porion.
The reference landmarks used for cephalometric measurements are described in Table 1
Table 1
Reference cephalometric landmarks
Landmark
|
Abbreviation
|
Description
|
Crista galli
|
Cg
|
The most superior point of the crista galli of the ethmoid bone
|
Basion
|
Ba
|
The median point on the anterior margin of the foramen magnum
|
Porion
|
Po
|
The highest point on the roof of the external auditory meatus
|
Orbitale
|
Or
|
The deepest point on the infraorbital margin
|
Condylion superius
|
Cdsup
|
The most superior point of the condyle head
|
Condylion medialis
|
Cdmed
|
The most medial point of the condyle head
|
Condylion lateralis
|
Cdlat
|
The most lateral point of the condyle head
|
Condylion posterius
|
Cdpost
|
The most posterior point of the condyle head
|
Sigmoid notch
|
S
|
The most inferior point of sigmoid notch
|
Gonion lateralis
|
Golat
|
The most lateral point of the gonion area
|
Gonion posterius
|
Gopost
|
The most posterior point of the gonion area
|
Gonion inferius
|
Goinf
|
The most inferior point of the gonion area
|
Menton
|
Me
|
The most inferior point on mandibular symphysis
|
First maxillary molar
|
6
|
Occlusal fossa of the maxillary first molar
|
Mandibular canine
|
3
|
Cuspal tip of the mandibular canine
|
The CBCT measurements (Table 2) were performed in frontal, laterolateral right, laterolateral left, posteroanterior and submentovertex views. Each measurement was performed on the initial and final CBCT. Also, the size of the right and left masseter muscles was evaluated with widget present in Dolphin. In frontal view, the size of each muscle was measured by adjusting the translucency instrument, to discriminate soft from hard tissues.
Table 2
Cephalometric measurements
|
Landmarks
|
Pre-treatment
|
Post-treatment
|
Results
|
FRONTAL VIEW (F)
|
Menton deviation
|
Distance from Me to MSP
|
4.2 mm (moderate deviation)
|
1.3 mm (slight deviation)
|
Δ: − 2.9 mm
|
Right masseter muscle
|
Maximum length and width
|
Lenght: 55.4 mm
Width: 15.7 mm
|
Lenght 61.5 mm
Width: 19.4 mm
|
Δ: + 6.1 mm
Δ: + 3.7 mm
|
Left masseter muscle
|
Maximum length and width
|
Lenght: 51.0 mm
Width: 11.3 mm
|
Lenght 54.3 mm
Width: 14.9 mm
|
Δ: + 3.3 mm
Δ: + 3.6 mm
|
LATEROLATERAL VIEW (LL)
|
Vertical facial growth pattern
|
Angle from SN to GoGn
|
30.1° (mesofacial)
|
32.5° (mesofacial)
|
Δ: + 2.4 °
|
Frankfort-mandibular plane angle (FMA)
|
Angle from FH to GoGn
|
13.6° (hypodivergent)
|
16.8° (hypodivergent)
|
Δ:+ 3.2 °
|
Sagittal facial growth pattern (ANB)
|
Angle from A to N to B
|
0.9° (class I)
|
2.5° (class I)
|
Δ: + 1.6°
|
Right-left difference in lateral ramal inclination;
|
Angle from Cd post - Go post to FH
|
Right: 74.7°
Left: 73.4 mm sx
|
Right: 77.1°
Left: 71.8°
|
Δ: +2.4°
Δ: − 1.6°
|
Right left difference in ramus length (without condyle and gonial angle)
|
Distance from Copost gopost
|
Right: 37.7 mm
Left: 33.8 mm
|
Right: 38.9 mm
Left: 41.6 mm
|
Δ: + 1.2 mm
Δ: + 7.8 mm
|
Right-left difference in ramus length (with condyle and gonial angle)
|
Distance from Cdsup to Go inf
|
Right: 50.9 mm
Left: 48.9 mm
|
Right: 55.8 mm
Left: 54.6 mm
|
Δ: + 4.9 mm
Δ: + 5.7 mm
|
Right-left difference in condylar height
|
Distance from Cdsup to S
|
Right: 18.3 mm
Left: 18.1 mm
|
Right: 17.3 mm
Left: 20.2 mm
|
Δ: -1.0 mm
Δ: + 2.1 mm
|
POSTERO-ANTERIOR VIEW (PA)
|
Right-left difference in maxillary height
|
6 to FH
|
Right: 29.0 mm
Left: 27.2 mm
|
Right: 35.8 mm
Left: 37.0 mm
|
Δ: + 6.8 mm
Δ: + 9.8 mm
|
Right-left difference in frontal ramal inclination
|
Angle from Cdlat-Golat to MSP
|
Right: 20.4°
Left: 16.5°
|
Right: 14.9°
Left: 16.9 °
|
Δ: -5.5°
Δ: + 0.5°
|
Right-left difference in mandibular body height
|
Distance from 3 to GoGn
|
Permanent canines not erupted
|
Right: 53.1 mm
Left: 33.3 mm
|
Not evaluable
|
Intercondilar distance
|
Distance from right Cdmed to left Cdmed
|
74.0 mm
|
83.3 mm
|
Δ: +9.3 mm
|
Extracondilar distance
|
Distance from right Cdlat to left Cdlat
|
102.7 mm
|
107.9 mm
|
Δ: +5.2 mm
|
Maximum width of the left condyle
|
Distance from Cdlat to Cdmed
|
15.0 mm
|
16.1 mm
|
Δ: + 1.1 mm
|
Maximum width of the right condyle
|
Distance from Cdlat to Cdmed
|
15.1 mm
|
16.5 mm
|
Δ: +1.4 mm
|
Right-left difference in condyle – MSP distance
|
Distance from Cdlat to MSP
|
Right: 50.3 mm
Left: 52.3 mm
|
Right: 51.7 mm
Left: 53.8 mm
|
Δ: + 1,4 mm
Δ: + 1,5 mm
|
SUB-MENTOVERTEX VIEW (SMV)
|
Right-left difference in mandibular body length;
|
Me-Gopost,
|
Right: 76.4 mm
Left: 74.9 mm
|
Right: 77.4 mm
Left: 82.4 mm
|
Δ: + 1 mm
Δ: + 7.5 mm
|
Legend: Δ Difference (posttreatment data – pretreatment data), FH Frankfort Horizontal plane, PO anteroposterior reference plane, MSP midsagittal reference plane, GoGn mandibular plane |