2019, Number 4
Treatment of skeletal class III patient, using maxillary plates. A case report
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ABSTRACT
Introduction: Skeletal class III is one of the most difficult malocclusions to treat in patients, because the growth pattern is unpredictable. Its association may be due to hypoplasia of the maxilla, mandibular hyperplasia, or a combination of both. It is present a clinic case of correction of class III relationship through the placement of skeletal anchor plates in the maxilla. C linical case: 12-year-old male patient, without the presence of pathological data, whoever was consulted refers to "my jaw is grown". A skeletal class III is diagnosed by maxillary hypoplasia with a hypodivergent growth type and a brachifacial biotype. He has a bilateral class III molar, class canine not established, lip incompetence. The treatment was carried out in two phases, the first orthopaedic phase, where the correction of the class III relationship is intended employing the placement of skeletal anchorage plates, with the use of class III elastics and progressive sequence. The second orthodontic phase where the stages of treatment, alignment, leveling, closing of spaces, consolidation, detailing and retention are found. The skeletal class I was successfully obtained, with good aesthetic, dental and functional results. Conclusion: Making a good diagnosis is a key to achieving the objectives set in orthodontic treatment. In early age class III patients, orthopaedic treatment with the use of intermaxillary plates combined with orthodontic treatment favors skeletal and dental correction.INTRODUCTION
Zere et al1 refers to the classification of Edward H. Angle, who in 1899 classified malocclusions into class I, class II and class III based on the relationship of the maxillary and mandibular first permanent molar. Gradually, Angle's classification was modified, concerning growth pattern and maxillomandibular relationship. Therefore, the class III relationship suggests that the mandible has acquired a more mesial position about the maxilla and/or the skull base. Class III malocclusion is one of the most difficult to treat due to the unpredictability of the growth pattern.2 It may be associated with deficient maxillary growth, excessive mandibular growth, or a combination of both, together with vertical and transverse malformations. The etiology of class III malocclusion is multifactorial, since it is the result of a distortion of normal development, the interaction between hereditary genetic factors, and environmental factors.1 Meyns et al3 mentions that Ellis and McNamara found that 65-67% of class III malocclusions are characterized by a deficiency of the maxilla. Therefore, most treatment modalities are based on protraction of the maxilla. Class III malocclusion is more prevalent in the American continent with 5%, with 9.1% in Latinos, and 8.3% in Mexican Americans.1
Other relevant aspects concerning the diagnosis that should be considered are family history, growth pattern and potential, as well as the patient's age.4 With the aim of growth redirection when the jaw is the primary aetiological factor, the types of treatment according to age consist of three fundamental stages: a preventive treatment from 4-7 years, an interceptive treatment from 7-10 years and a corrective treatment from 10-12 years.5 The options for the correction of class III in growing patients consist of two main categories: intraoral appliances such as myofunctional appliances such as the Frankel III, Bionator III, Eschler, and others, and extraoral appliances such as facial masks with or without expansion and with dental or skeletal anchorage, assisted corticotomy for protraction, among others.6 The treatment of young patients with a deficient maxilla is generally aimed at achieving positive protrusion through a combination of skeletal and dentoalveolar effects.7 Bone-anchored maxillary protraction is an effective treatment modality for the correction of this malocclusion.8
Esenlik et al9 the introduction of a new approach to the orthopaedic treatment of class III malocclusions employed by Clerck et al8 achieving maxillary protraction through the use of intermaxillary elastics in mini-plates that go on the zygomatic ridges of the maxilla and in the anterior region of the mandible. With this approach, maxillary traction can be applied 24 hours a day. This intraoral approach became very popular among orthopaedic treatment alternatives.
The objective of the present paper is to show a clinical case of a patient diagnosed with skeletal class III treated in two phases treatment: the first one using orthopedia with skeletal anchorage, and the second one the orthodontic phase.
CASE REPORT
12-year-old male patient with no pathological or odontological data, attending the Orthodontic Specialty Clinic of the University of Guadalajara. The reason for consultation was "my jaw is overgrown".
Extraoral analysisHe presents abnormal growth and development, with a brachyfacial biotype, prominent chin, lip incompetence, adenoid facies, depressed midfacial third, facial asymmetry on the right side, coincident smile lines, upper and lower dental midline deviated to the right, concave profile, hypodivergent growth, a long and oval face, thick and prominent lips (Figure 1A).
Intraoral analysisIntraoral photographs show a bilateral class III molar relationship, unestablished class canine, anterior crossbite, midline deviated 3 mm to the right both upper and lower (Figure 1B).
Model analysisBolton's analysis presents a mandibular excess of 6-6: 3.5 mm and a mandibular excess of 3-3: 3 mm. It presents an upper arch length discrepancy of -10.3 mm and a lower arch length discrepancy of -7 mm (Figure 2).
Radiographic analysisLateral radiography: in the Steiner cephalometry was digitally traced in Dolphin version 9.0 (Figure 3A), a skeletal class III is found due to maxillary hypoplasia, the mandibular angle is decreased, indicating upward and forward rotation. The dental criteria show proclination and protrusion of the maxillary and mandibular incisors. The soft tissue analysis shows a mentolabial sulcus and a decreased nasolabial angle, and the lower lip is slightly in front of the Steiner E line (Table 1).
Panoramic X-ray: there is a 1:2 crown-root ratio, normal eruption pattern, presence of lower and upper third molars in apico-formation, bone ridge levels with adequate height, symmetrical condyles, no signs of periodontal disease (Figure 3B).
Diagnosis: skeletal class III due to maxillary hypoplasia, with a brachycephalic biotype, class III molar, class canine not established, horizontal overbite: -1 mm, vertical overbite: 1.5 mm, DLA: upper: -10.3 mm, lower: -7 mm, lower midline 3 mm to the right, upper and lower teeth in protrusion and proclination.
Treatment objectives: improve profile, obtain class I canine and class I molar, correct dental midlines, obtain adequate anterior guidance, correct maxillary, and mandibular crowding, improve upper and lower arch form.
ALTERNATIVE TREATMENTS
- 1. The first treatment alternative was orthognathic surgery for skeletal class III, this process was evaluated due to the maturation stage of the patient, which could lead to post-surgical relapse.
- 2. Another alternative was treatment with myofunctional orthopaedic appliances to optimize maxillary redirection with the use of a facial mask for maxillary protraction or the use of a myofunctional appliance such as the Bionator or the Frankel; this option was considered late due to the patient's maturation process, which meant that treatment would have limited possible results.
- 3. A viable and conservative alternative was the proposal of treatment of dental compensation with fixed appliances and extractions, but with the limitations of not correcting skeletal class III, and being conditioned to obtain fewer treatment objectives.
- 4. The treatment accepted by the patient was the two-stage process: the orthopaedic phase with the placement of intermaxillary plates and the use of class III elastics for skeletal correction, and subsequently the orthodontic phase to achieve the dental objectives, obtaining the best possible result.
TREATMENT PROGRESS
During the orthopaedic phase, the 2.0 mm titanium skeletal anchorage plates were placed, each with two 2. 0 × 9 mm screws placed in the mandibular part between canines and laterals on both sides and in the maxillary part in the zygomatic arch at the root level of the second molar on both sides, which is a procedure performed under general anesthesia but ambulatory. One month after the surgical procedure, a Cone Beam tomography was taken to evaluate the osseointegration of the plates and subsequently the placement of class III elastics with 150 g (Figure 4A). In this phase of the treatment, turbo bites were placed on the upper first molars to achieve anterior disocclusion and to make the mechanics more effective, together with the class III elastics which were used for 10 months (Figure 4B), starting with light forces of 150 grams until reaching 450 grams per side. Then, the patient presented a better maxillomandibular relationship and the orthodontic phase continued to correct the occlusion (Figure 5).
In the orthodontic phase, the extractions of the upper and lower first premolars were planned due to the dental compensations and the present crowding. We continued with the cementation of Alexander brackets, bands on first molars, and tubes on upper and lower second molars with slot 0.018". In terms of alignment and leveling, as there is a positive overjet and the profile needs to be improved, extractions are carried out to release the crowding, with a sequence of 0.012" nickel-titanium archwires, 0.016" thermo activated nitinol, 0.016" × 0.022" thermo activated nitinol, and 0.016" × 0.022" upper and lower steel over a period of 10 months. In the work phase, a 0.016" × 0.022" steel was used, spaces were closed with a double delta loop in a period of seven months. In the detailing, a 0.016" steel arch with shortstops in the lower part, and in the finishing phase the use of elastics for settling in thermal arches for a period of eight months. For final retention, an upper and lower circumferential is indicated with the 24-hour indication for use.
Good facial harmony and aesthetics were obtained (Figure 6A), class I molar and canine were consolidated, a correct horizontal and vertical overbite was obtained and the treatment was completed with an ovoid arch form in both arches (Figure 6B). In the lateral skull radiograph (Figure 7A) as well as in the Steiner cephalometry (Table 1) the skeletal class I, the norm-divergence, the adequate anterior guidance with which the patient ends, and the positive changes in the profile were achieved. The final panoramic radiograph showed good root parallelism, 24 teeth present, with teeth 18 and 28 in eruption process, 38 retained, 48 impacted. The patient was referred to the Oral Surgery Department for the extraction of the third molars. The lower left plate was observed between teeth 32 and 33, at the time of the surgical approach to remove it, it was found to be osseointegrated, and since its removal implied the removal of a considerable amount of bone tissue, it was decided to leave it (Figure 7B). The study models show a coincident dental midline, good posterior seating, and an adequate anteroposterior relationship (Figure 7C). In the superimposition of the cephalometric tracings, the maxillary and mandibular positioning are analyzed, determining an adequate skeletal correction achieved post-treatment in reference to the stable anatomical points in the maturation stage and an adequate dental position (Figure 8).
DISCUSSION
The main factor determining an optimal long-term outcome of maxillary protraction and mandibular redirection will depend on the amount of advancement, direction of growth, and stage of development. Lin et al10 mentions that maxillary protraction at an early stage may exhibit a more effective treatment response but may also have a greater tendency to relapse due to the potential for mandibular growth in this type of patient. In the case report, it was established as an important criterion to have a periodic assessment at the end of treatment to analyze the trend of mandibular growth and thus avoid relapse. Adequate occlusion is of utmost importance, as it determines good condylar position and therefore better post-treatment stability.
Meyns et al3 mentions that the use of skeletal anchorage has several advantages, including improved patient compliance with the use of intraoral elastics, better continuous traction response rather than heavy and interrupted forces during the day, in our patient we found good cooperation in the use of elastics without referring discomfort when using them. Heymann et al11 and Almuzian et al12 mention that the use of intermaxillary elastics by means of anchorage devices improves skeletal relationships in patients with a maxillary deficiency with minimal dentoalveolar change, as well as eliminating the use of extraoral appliances, corroborating this with cephalometric superimposition where the skeletal result obtained is verified and with minimal changes in dental inclinations, favoring the long-term stability of the treatment. We found an increase in the mandibular plane, a counterclockwise rotation of the palatal plane, as well as a mandibular posterior-rotation, which is attributed to the correction of the skeletal class III, a favourable change in ANB, as well as an adequate horizontal and vertical overbite. This result was similar to the study carried out by Fakharian et al,13 he mentions that after the orthopaedic and orthodontic phase there is an inclination of the mandibular incisors which is attributed to the tongue pressure after the elimination of the anterior crossbite and the increase of the distance between the upper and lower incisors. The clinical case reported differs from the aforementioned author as the cephalometric reports and the superimposition show an adequate relationship of the lower incisors in their bony bases, due to the fact that in the protraction both the maxilla and the mandible were manipulated for the correction of class III and the extractions were carried out to comply with dental stability.
CONCLUSION
Orthopaedic treatment using intermaxillary plates in conjunction with orthodontic treatment is a good alternative in skeletal class III patients who are in a stage of consolidated maturation but are still considered young for orthognathic surgery due to the high rate of postsurgical relapse. The method can achieve a skeletal class I along with a stable occlusion without having unfavorable changes in the dental compensations and at the same time obtain facial harmony. We successfully achieved skeletal class I, class canine and molar I, adequate anterior guidance, as well as good aesthetic and functional results.
REFERENCES
AFFILIATIONS
1 Especialidad de Ortodoncia, Departamento de Clínicas Odontológicas Integrales, Centro Universitario de Ciencias de la Salud. Universidad de Guadalajara. México.
2 Cirujano Maxilofacial. Clínica de Cirugía Maxilofacial. Centro Médico Puerta de Hierro. Zapopan, Jalisco.
CORRESPONDENCE
José de Jesús García López. E-mail: pepegalop@yahoo.com.mxReceived: Abril 2020. Accepted: Junio 2020.