Skeletal Class III Malocclusion in an Adult Patient – Orthodontics versus Orthognathic Surgery: Is there Another Alternative?

Introduction

According to the classification of Dr. Angle, Class III is the malocclusion in which the vestibular groove of the lower first molar is located mesial to the mesiobuccal cusp of the upper first molar.^[1]

It is necessary to distinguish a dental Class III malocclusion from skeletal one because in the second, the malocclusion is due to a disproportion in the bony bases, which may be due to a retrognathism of the upper jaw, a mandibular prognathism, or a combination of both.^[2,3]

The highest prevalence of Class III malocclusions is found in Asia (12%) and Europe, values ranging between 1.5% and 5.3% and in Caucasians in North America between 1% and 4%.^[4,5]

The skeletal deformities are the result of the presence of anomalies in the position of the maxilla and mandible. In malocclusions in which a single bone is involved, maxillary retrusion is more common (19.5%) than a mandibular protrusion (19.2%), although the presence of these two features in a combined form is more common (30.2%).^[6,7]

In the treatment of skeletal Class III malocclusion in adults, there are basically two treatment alternatives: orthodontic treatment and surgical treatment combined with orthodontics. The choice of one or the other will depend on several factors; one of the main ones will be the degree of bone discrepancy, since orthodontic camouflage can only be done when Class III malocclusion is mild. On the other hand, not all patients are willing to undergo surgical treatment, due to its cost, invasive nature, or health conditions, despite being the ideal option from the orthodontic point of view.^[8-10]

In cases in which, in addition to the sagittal problem, there is a transversal problem due to maxillary compression, it is possible to perform a segmented Le Fort (combining Le Fort I with osteotomies that allow disjunction). Another option is the previous execution of a surgically assisted rapid palatal expansion (SARPE).^[11-13]

Federico Hernández Alfaro describes the SARPE performed on 257 patients, under local anesthesia and sedation, making a complete Le Fort I without mobilization, which achieves a total release and bipartition of the maxilla that guarantees skeletal distraction and prevents a damaging load at the dental level.^[14]

Due to the number of patients with Class III malocclusion with maxillary compression who refuse treatment with orthognathic surgery, we have proposed a less invasive solution for the patient, more economically affordable, and that obtains very good results, both esthetically and functionally. This alternative consists in the performance of a SARPE under local anesthesia and sedation, and the placement of miniplates, two superiors at the level of the pterygoid and two inferiors in the symphysis, between the lateral incisors and the canines.

The case presented is a Class III malocclusion with maxillary compression, mandibular asymmetry, and deviation of the lower line to the right.

Although the ideal option to correct all the problems was orthognathic surgery, the patient decided to undergo treatment of SARPE + temporary anchorage devices (TADs), assuming that the mandibular asymmetry would not be corrected.

Diagnosis and etiology

The patient is an adult of 28 years old presenting with transversal and sagittal hypoplasia of the maxilla, skeletal asymmetry, deviation of the lower line to the right, and crowding.

Clinical frontal examination revealed an asymmetrical face. The profile assessment revealed concave profile, with anterior facial divergence, flat cheekbone contour, and pure esthetics of the smile in the frontal and lateral views [Figure 1]. When we analyzed the smile in detail, we observed crowding, poor coordination of the dental midlines, and the upper teeth are worn [Figure 1].

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Figure 1

Initial extraoral photographs

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Intraoral examination revealed Class III molar and canine relation on both sides. The mandibular midline was deviated 4.5 mm to the right. The patient had upper and lower crowding and compression in the maxilla [Figure 2].

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Figure 2

Initial intraoral photographs

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Temporomandibular joint (TMJ) examination revealed a little discrepancy between centric relation and centric occlusion, and the patient complained of pain in the joint.

Cephalometric examination revealed retrognathic maxilla (SNA 73º) and Class III malocclusion (Witts -10mm and ANB -4º) [Figure 3 and Table 1].

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Figure 3

Initial teleradiograph and orthopantomography

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Table 1 Cephalometric values

Value	Mean	Initial	Treatment pre-SARPE	Final
SNA (°)	82±3.5	73	73	76.5
SNPg (°)	80±3.5	77	77	77
SNB (°)	80±2	77.5	77.5	77.5
ANPg (°)	2±1.5	−4.5	−4.5	−1
ANB (°)	2±1	−4	−4	−0.5
SN/ANS-PNS (°)	8±3.0	14.5	14.5	14.5
SN/GoGn (°)	33±2.5	38	38	38
ANS-PNS/GoGn (°)	25±6.0	20	20	20
+1/ANS-PNS (°)	110±6.0	108	108	119.5
−1/GoGn (°)	94±7.0	83	91	82
Overjet (mm)	3.5±2.5	−0.3	−2	0.3
Overbite (mm)	2±2.5	1.7	1.5	2
Interincisal (°)	132±6.0	147	142	137
Witts	0±1	−10	−10	−4

SARPE: Surgically assisted rapid palatal expansion

Treatment progress

Due to the large number of adult patients who present Class III malocclusion but decide not to undergo orthognathic surgery, despite being the ideal option, for different reasons explained above, we decided to devise an intermediate option between camouflage and orthognathic surgery.

When a SARPE is performed to solve maxillary compression, the palatine and pterygoid sutures are released. If we also add some miniplates at the level of the pterygoids each side by vestibular and others between the lower lateral incisors and the lower canines by vestibular, we can pull forward the maxilla, benefiting from the release of the pterygoid sutures made in the SARPE. We have defined this technique as SARPE + TADs.

Orthodontic treatment combined with SARPE + TADs consists of three phases: presurgical orthodontic treatment, surgical treatment, and postsurgical orthodontic treatment.

In patients with skeletal problems and TMJ pain, we propose to use a split in upper arch, and we decompensate the lower arch to make sure which is the real transversal and sagittal problem for 4 months.

After this first phase, we did a teleradiograph [Figure 4 and Table 1] and a cone-beam computed tomography (CBCT) to measure the transversal problem [Figures 4 and 5]. The patient first needed a surgery to expand the maxillary by SARPE technique before the placement of brackets in the upper arch. In our protocol, this surgery is considered ambulatory because it is performed under local anesthesia and sedation on an outpatient basis in 30 min [Figures 6-9].

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Figure 4

Cone beam computed tomography before surgically assisted rapid palatal expansion

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Figure 5

Teleradiograph before surgically assisted rapid palatal expansion

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Figure 6

Extraoral photographs before surgically assisted rapid palatal expansion

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Figure 7

Intraoral photographs before surgically assisted rapid palatal expansion

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Figure 8

Extraoral photographs after surgically assisted rapid palatal expansion

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Figure 9

Intraoral photographs after surgically assisted rapid palatal expansion

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Next, the patient underwent the operation of SARPE + TADs. The activation was 3 turns per day, and an intermaxillary elastic was placed from the right upper miniplate to the lower right one and another from the upper left miniplate to the lower left one, with forces of 200–400 g per side for approximately 24 h a day (the patient can only remove them to eat and brush her teeth) [Figure 8].

Once the desired expansion was obtained, we made a CBCT to confirm that the expansion was completely corrected and to measure the sagital advance of the maxilla [Figure 10].

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Figure 10

Cone-beam computed tomography after maxillary expansion

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One month later of the last turn of the screw, we bonded the brackets in the upper arch and we closed the diastema and coordinated the dental arches to achieve an adequate occlusion and esthetics of the smile (to center the midlines, obtain molar and canine in Class I, achieve overbite with intermaxillary elastics, and get a correct smile arch) [Figure 11]. The elastics of the miniplates continued to be placed until the patient’s sagittal problem was resolved.

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Figure 11

Intraoral photographs during the treatment

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During the treatment, we used the following arches:

• Alignment: 0.014 NiTi and 0.016 NiTi

• Leveling: 0.017 × 0.025 NiTi.

• Torque and space closure: 0.019 × 0.025 steel wire

• Finishing: 0.018 steel wire with bindings.

Treatment results

After the treatment, the brackets and TADs were removed and final radiographs were taken.

The result after the treatment is acceptable. We obtained a significant improvement in alignment, occlusion function, coordination of the midlines, and esthetics of the smile in frontal and lateral views and facial esthetics. The mandibular asymmetry was not corrected since orthognathic surgery would have been necessary for this purpose [Figures 12 and 13].

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Figure 12

Final extraoral photographs

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Figure 13

Final intraoral photographs

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The lingual occlusion is acceptable, and we can see it with the dental scan [Figure 14].

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Figure 14

Final intraoral scan

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In the CBCT, we can observe that the roots are in the middle of the alveolar bone, and there is no root resorption [Figure 15].

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Figure 15

Final cone-beam computed tomography

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Cephalometric examination showed an advance of the maxilla (SNA 76.5º), a Class I malocclusion (Witts -4 and ANB -0.5º) and a correct interincisal angle (137º) [Figure 16 and Table 1].

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Figure 16

Final teleradiograph

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The main changes obtained in the treatment of SARPE + TADs in the patient are as follows [Table 1]:

• There have been no rotations of the maxillary or mandibular plane

• The Class III malocclusion has been completely corrected (ANB from −4º to −0.5º, Witts from −10 to −4 mm)

• Proper advancement of maxilla has been achieved (SNA from 73º to 76.5º)

• The inclination of the upper incisor (119.5º) and the lower (92º) is corrected

• The interincisal angle is corrected (137º)

• The overjet decreased from -2 to 0mm.

In order to visualize the changes produced after the treatment of the patient with SARPE + TADs, the superposition of the tracings after SARPE and final, on the anterior cranial base, was made, showing all the changes previously exposed [Figure 17], and a comparison between intraoral and extraoral photographs was made [Figures 18 and 19].

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Figure 17

Superposition of the tracings before surgically assisted rapid palatal expansion (blue) and final (red) on the anterior cranial base

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Figure 18

Comparison between initial and final extraoral photographs

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Figure 19

Comparison between initial and final intraoral photographs

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Two years later, the occlusion function is stable. The esthetic of the smile is acceptable. The patient does not have TMJ problems [Figures 20 and 21].

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Figure 20

Retention extraoral photographs

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Figure 21

Retention intraoral photographs

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Conclusion

In cases where there are a maxillary compression and a mild or moderate Class III malocclusion, and/or when the patient rejects the option of orthognathic surgery due to its economic cost, health conditions, or invasive nature, the treatment of SARPE + TADs is an option that obtains very acceptable results, both functionally and esthetically, and allows patients to solve skeletal problems that until now could only be corrected with orthognathic surgery.