Class III Malocclusion Treated with an Orthopedic Protraction Face Mask During Mixed Dentition, Followed by Invisalign Aligners to Correct Anterior Crossbite Occurring after Relapse During Adolescence

An eight-year-old male patient presented with a class III malocclusion on a skeletal class III pattern with an average lower face height, an anterior crossbite, slightly anterior lower crowding, and good oral hygiene; the parents were concerned about his crossbite. The aim of treatment was to correct the anteroposterior discrepancy by using a face mask during the 12-month mixed dentition period, during which the patient achieved a good result. However, after seven years of retention, the patient presented an anterior crossbite with a skeletal class I pattern and an average lower face height. He decided to wear clear aligners for treatment; 28 sets of clear aligners, which were changed every two weeks for twelve months, were necessary to achieve anterior crossbite correction.

Introduction

Class III malocclusions occur when the lower central incisal edges lie anterior to the cingulum plateau of the palatal surface of the upper central incisors [1]. Malocclusions are considered a public health problem [2]. The prevalence of grade III malocclusions, which depends on the geographic region, can vary from 3% to 28% [3]. As all malocclusions are caused by a deviation from the normality of average growth, their etiology is related mainly to genetic heredity due to the skeletal class III pattern and, to some extent, to environmental factors [4]; malocclusions are also associated with genes such as Indian hedgehog homolog (IHH), insulin-like growth factor-1 (IGF-1), vascular endothelial growth factor (VEGF), and parathyroid hormone-like hormone (PTHLH) [5]. The skeletal features include a reduced cranial base angle that contributes to the forward position of the mandible [6], along with maxillary retrusion that influences 60% of the cases; some cases involve a short cranial base, with a short maxillary portion that is small and narrow relative to the mandible, which tends to be broad, and the lower position of the tongue contributes to a posterior crossbite [7]. An obtuse gonial angle of the cranial base is related to an average or reduced lower face height, which also exhibits a transverse skeletal discrepancy [8]. Soft tissues are not involved in the etiology of malocclusions but facilitate dentoalveolar compensation for the skeletal base, pro-inclined upper incisors and retro-inclined lower incisors [9]. Facial growth tends to be unfavorable and unpredictable during adolescence.

Different treatment options, including functional appliances such as the Frankel type [10], protracted face mask [11], chin cap [12] and bone-anchored maxillary protraction [13], have been proposed for class III malocclusions that occur during the mixed dentition period. Early orthopedic treatment with a face mask is skeletally and dentally effective in the short term [14]; in the long term, some patients relapse to a negative overjet [15], and the skeletal change is not maintained after six years; 36% of patients need orthognathic surgery [16]. For those patients who relapse with anterior crossbite after short-term protraction face mask treatment [17], the first premolars and second molars in the upper arch could be extracted if the skeletal pattern allows camouflage of the malocclusion [18]; alternatively, it is possible to treat the anterior crossbite without extraction. Here, a case involving orthopedic face mask treatment during mixed dentition is presented; good results were obtained in the short term. However, the patient relapsed after seven years, producing an anterior crossbite in a skeletal I pattern; consequently, he was treated with clear aligners without extractions to correct the anterior crossbite through a comfortable and easy treatment.

Case Presentation

An eight-year-old male patient presented with a class III malocclusion in a skeletal class III pattern with an average lower face height, an anterior crossbite, slightly anterior lower crowding, and good oral hygiene.

Medical History

No abnormalities were determined according to the relevant medical history. The parents attended because they were concerned about their child’s anterior crossbite, and the patient’s attitude was keen.

Clinical Examination

Soft Tissue Pattern: During the evaluation of the patient’s soft tissue pattern, the lips were competent, the tongue functioned with an upper incisor/palate swallowing pattern. Moreover, there was no relevant history of past habits, and the temporomandibular joint showed no evidence of TMJ dysfunction. The patient was in mixed dentition and had no apparent facial asymmetry (Fig. 1).

Fig. 1. Pretreatment extraoral photographs.

Occlusion

There was a class III incisor relationship, and the centerline was well aligned, with an overjet of 3 mm and an overbite of 4 mm. The buccal occlusion on both sides exhibited a class III relationship, there was no crowding in the upper and lower labial segments, and the upper and lower labial segments were well aligned. However, the patient exhibited an anterior crossbite, albeit with no mandibular anterior displacement (Fig. 2).

Fig. 2. Intraoral pretreatment photographs (A–F).

Etiology

The patient was determined to have a skeletal class III anterior crossbite.

Cephalometric

The McLaughlin cephalometric analysis confirmed the Class III skeletal pattern (ANB-1°) with a retrognathic maxillary (SNA 75.1°) and slightly retrognathic mandibula (SNB 76.1°), the upper incisors retroclined (UI/MX 99.8°), the lower incisors proclined (IMPA 103.5°), and the lower face height slightly decreased (FMA–MP-FH 25.4°) (Fig. 3; Table I). The panoramic X-ray revealed a mixed dentition patient without any pathological features. All teeth were present during this period of normal dentition development, and third molars were not visible (Fig. 4).

Fig. 3. McLaughlin cephalometric tracing confirmed the skeletal class III pattern with a slight reduction in the height of the lower face and reclining upper incisors and proclaiming lower incisors.

Table I. Pre-Treatment Cephalometric Analysis

Measurements	Value	Norm
Horizontal Skeletal
SNA o	75.2	82.0
SNB o	76.1	80.0
ANB o	−0.9	2.0
Vertical Skeletal
FMA (MP-PH) o	25.4	26
MP-SN o	32.0	33.0
Palatal-Mand Angle o	26.8	28.0
Palatal-Occ Plane o	13.0	10.0
Mand Plane to Occ Plane o	13.8	14.2
Mx occlusal plane (Mx OP-Na-Perp o	101.6	95.6
Anterior Dental
U-Incisor protrusion (Ui-Apo) mm	4.0	6.0
L1 Protrusion (L1-Apo) mm	7.6	2.0
U1-Palatal Plane o	99.8	110.0
U1 Occ Plane o	67.2	54.0
L1 Occ Plane o	62.7	72.0
IMPA o	103.5	95.0

Fig. 4. Normal development during the mixed dentition, with no pathological features; the third molars are not visible.

Aims of Treatment

The therapeutic goals were to correct the anterior crossbite, establish a class I molar and canine relationship, and improve the anteroposterior discrepancy.

Treatment Plan

The first stage consists of the following:

1. Placement of a reverse headgear face mask (Fig. 5).

Fig. 5. The aim of the treatment was to correct the anteroposterior discrepancy via a protracted face mask during the mixed dentition period of 12 months.

2. Review.

Treatment Progress

The patient was instructed to wear the face mask as much as possible. However, the pads produced tissue irritation; therefore, the patient had to place small pieces of cloth below the pads. At three months of treatment, the patient had an edge-to-edge incisor relationship. At six months of treatment, he exhibited a positive overjet; at this point, he had to wear the face mask only at night over a period of five months for retention. The patient was scheduled for removal of the face mask, after which he moved to the countryside for some time (Figs. 5 and 6).

Fig. 6. During orthopaedic treatment (A, B, and C), The patient achieved good results after 7 months of treatment and 5 months of retention while wearing the face mask only at night (D, E, and F).

After seven years of retention, the patient came in for a reassessment of their occlusion. He presented a class III incisor relationship involving the upper incisors (Figs. 7 and 8).

Fig. 7. After seven years out of retention, the patient presented an anterior crossbite in a skeletal class I pattern, with an average lower face height. Extraoral photographs (A, B and C), Intraoral photographs (D, F, F, G, H and I).

Fig. 8. McLaughlin cephalometric tracing confirmed the skeletal class I pattern with average in the height of the lower face and retroclining upper incisors and proclining lower incisors.

Cephalometric

The McLaughlin cephalometric analysis confirmed the Class I skeletal pattern (ANB 2.5°) with a retrognathic maxillary (SNA 76.3°) and slightly retrognathic mandibula (SNB 73.8°), the upper incisors retroclined (UI/MX 94.8°), the lower incisors proclined (IMPA 103.6°), and average the lower face height (FMA–MP-FH 25.9°) (Table II).

Table II. Cephalometric Analysis After 7 Years of Treatment with Reverse Headgear Face Mask

Measurements	Value	Norm
Horizontal Skeletal
SNA o	76.3	82.0
SNB o	73.8	80.0
ANB o	2.5	2.0
Vertical Skeletal
FMA (MP-PH) o	25.9	26
MP-SN o	38.1	33.0
Palatal-Mand Angle o	29.6	28.0
Palatal-Occ Plane o	8.8	10.0
Mand Plane to Occ Plane o	20.8	14.2
Mx occlusal plane (Mx OP-Na-Perp o	95.1	95.6
Anterior Dental
U-Incisor protrusion (Ui-Apo) mm	9.4	6.0
L1 Protrusion (L1-Apo) mm	13.7	2.0
U1-Palatal Plane o	94.8	110.0
U1 Occ Plane o	76.4	54.0
L1 Occ Plane o	55.6	72.0
IMPA o	103.6	95.0

An orthodontic simulation with clear aligners was shown to the patient. The patient decided to wear clear aligners for treatment, and optimized attachments were placed according to data from the ClinCheck software (Fig. 9).

Fig. 9. (A) Simulation of orthodontic treatment (B). Point contacts.

Treatment Progress

The patient had to wear 28 sets of clear aligners, which were changed every two weeks for six months to achieve anterior crossbite correction very quickly.

Treatment Results

The posttreatment assessment revealed the following: The patient achieved facial balance (Fig. 10), a class I canine relationship with an overjet of 2 mm and an overbite of 3 mm, the center line was coincident with the buccal segment relationship showing a class I molar relationship on both sides (Fig. 11). The patient exhibited functional occlusion, there was a normal canine guide excursion, and there were no complications encountered during orthodontic treatment; McLaughlin analysis was used to evaluate the cephalometric confirmed Class I skeletal pattern (ANB 3.9°) with a retrognathic maxilla (SNA 79.2°), a slightly retrognathic mandibula (SNB 75.3°), upper incisors at 101.7° (UI/MX), lower incisors at 96° (IMPA), and an normal lower face height at 28° (palatal, mandibular plane) (Fig. 12; Table III). The overall superimposition before and after treatment revealed changes in the skeletal pattern from class III to class I and changes in the inclination of the upper and lower incisors from class III to class I. All permanent teeth are present (Fig. 13). Facial growth occurred, and the height of the lower face increased. (Fig. 14). A fixed lingual bonded retainer was placed in the lower arch from 33 to 43, and the upper aligner was used as a retainer. The patient’s prognosis was good.

Fig. 10. Posttreatment photographs: extraoral.

Fig. 11. Posttreatment photographs: intraoral.

Fig. 12. McLaughlin cephalometric tracing confirmed the skeletal class I pattern with increased the height of the lower face and upper incisors at 102° and lower incisors at 96°.

Table III. Cephalometric Tracing: (A) Before Treatment, (B) After 7 Years Out of Retention of the Reverse Headgear, (C) Posttreatment, (D) Norms

Measurements	Value			Norm
Horizontal skeletal	A	B	C	D
	Before treatment	After 7 years of reverse Face Mask	Post treatment with aligners
SNA o	75.2	76.3	79.2	82.0
SNB o	76.1	73.8	75.3	80.0
ANB o	−0.9	2.5	3.9	2.0
Vertical
FMA (MP-PH) o	25.4	25.9	31.3	26
MP-SN o	32.0	38.1	33.2	33.0
Palatal-Mand Angle o	26.8	29.6	28.9	28.0
Palatal-Occ Plane o	13.0	8.8	9.2	10.0
Mand Plane to Occ Plane o	13.8	20.8	19.2	14.2
Mx occlusal plane (Mx OP-Na-Perp o	101.6	95.1	101.6	95.6
Anterior Dental
U-Incisor protrusion (Ui-Apo) mm	4.0	9.4	13.6	6.0
L1 Protrusion (L1-Apo) mm	7.6	13.7	8.1	2.0
U1-Palatal Plane o	99.8	94.8	101.7	110.0
U1 Occ Plane o	67.2	76.4	69.1	54.0
L1 Occ Plane o	62.7	55.6	64.3	72.0
IMPA o	103.5	103.6	96	95.0

Fig. 13. After orthodontic treatment with aligners, a Panoramic view of the X-rays showed permanent dentition with no pathological features; Three third molars are present except for the lower left third molar.

Fig. 14. Overall superimposition, registered on the sella-nasion line at the sella, black line: before treatment, red line: at the end of treatment.

Discussion

For many years, reverse headgear has been used as a treatment for children with mixed dentition who present with class III malocclusions [19]. The protraction of the face mask used in this patient achieved successful treatment of the class III malocclusion with maxillary retrusion in the short-term prognosis [20]. This success was obtained with one degree of maxillary protraction, two degrees of mandibular retrusion and three degrees between both maxillaries as an effect of treating the slight downward and backward mandibular rotation [21], which occurs as a result of the balance between growth and treatment outcome [22] and is related to the forward and upward direction of condylar growth [23] of this patient, who exhibited regular growth rotation of the mandible. Additionally, there was pro-inclination of the upper incisors and retro-inclination of the lower incisors, which contributed to the dental alveolar compensation of the class III malocclusion. Although in the short term, the patient experienced a correction of the class III malocclusion, after seven years out of retention, the patient had a relapse that produced an anterior crossbite on a skeletal class I pattern. Nevertheless, tracing the lateral skull after seven years during his recall appointment revealed a value of 2.5° of ANB. The degree of ANB improved the skeletal pattern from class III to class I. In patients wearing a protraction face mask, relapse in terms of long-term prognosis may be influenced by the difference in growth mechanisms between both maxillas when the maxillary protraction is eliminated and deciduous growth of the mandible continues, which causes relapse of the anteroposterior relationship [24]. Nevertheless, there was another opportunity to correct the anterior crossbite presented by the present patient by using fixed or removable appliances to avoid a surgical procedure. It is possible to treat crossbite patients who maintain a reasonable skeletal I pattern after reverse headgear treatment relapse, without extraction.

The patient asked for clear aligners for orthodontic treatment. Patients, especially those who are reluctant to wear fixed appliances, have been accepting clear aligners over the last two decades. The clear aligners are aesthetic, with less demineralization [25] and fewer periodontal problems [26]. The treatment of this patient with aligners to correct his anterior crossbite did not necessitate an upper expansion to allow buccal tipping of the upper incisors; the lower incisors were tipping lingually, as they were pro-inclined at 102° (IMPA). The cone beam tomography and scanning of the teeth were merged in the Invisalign platform, thereby allowing the calculation of the movement of the upper and lower incisors to be measured on the computer screen with a protractor to maximize the predictability of the movement and to reach the gold standard of the pre-adjusted fixed system of braces [27].

The patient was very keen to use the aligners, and he successfully wore 28 sets of aligners for at least 22 hours a day for six months, followed by six months of refinement aligners. A seven-day change protocol was adopted, which achieved good treatment results. Optimized attachments were placed according to the ClinCheck software, and interdental reduction was performed in the anterior labial segment to retro-cline the anterior lower teeth, achieving correction of the anterior crossbite [28].

Conclusions

Short treatment times and comfortable orthodontic treatment were provided by using clear aligners to correct a case of anterior crossbite that recurred after seven years out of retention post-treatment with a reverse headgear face mask.

Clear aligners can achieve functional and aesthetic results in correcting anterior crossbite if the patient cooperates well, which is the key to successful orthodontic treatment.