|Year : 2021 | Volume
| Issue : 1 | Page : 64-69
Comprehensive management of severe skeletal Class III malocclusion through a combined surgical and orthodontic approach
C Thiagu, Ratna Parameshwaran, Selva A Arockiam, Devaki Vijayalakshmi
Department of Orthodontics and Dentofacial Orthopaedics, Meenakshi Ammal Dental College, Chennai, Tamil Nadu, India
|Date of Submission||30-Mar-2020|
|Date of Decision||24-Oct-2020|
|Date of Acceptance||26-Nov-2020|
|Date of Web Publication||09-Mar-2021|
Department of Orthodontics and Dentofacial Orthopaedics, Meenakshi Ammal Dental College, Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
Management of skeletal Class III malocclusion requires a comprehensive approach since several factors such as severity of reverse overjet and facial divergence govern the treatment plan. Management of the nongrowing skeletal Class III individual with moderate-to-severe skeletal discrepancy is either by surgical management or orthodontic camouflage. Although various reports emphasize that both the treatment options are equally successful, the degree of correction which can be achieved differs. This report describes the comprehensive management of a case of severe skeletal Class III malocclusion through a combined surgical-orthodontic approach.
Keywords: Bilateral sagittal split osteotomy, fixed orthodontics, Le Fort I, mandibular prognathism, skeletal Class III malocclusion
|How to cite this article:|
Thiagu C, Parameshwaran R, Arockiam SA, Vijayalakshmi D. Comprehensive management of severe skeletal Class III malocclusion through a combined surgical and orthodontic approach. J Dent Def Sect. 2021;15:64-9
|How to cite this URL:|
Thiagu C, Parameshwaran R, Arockiam SA, Vijayalakshmi D. Comprehensive management of severe skeletal Class III malocclusion through a combined surgical and orthodontic approach. J Dent Def Sect. [serial online] 2021 [cited 2021 Apr 18];15:64-9. Available from: http://www.journaldds.org/text.asp?2021/15/1/64/310959
| Introduction|| |
The severity of skeletal Class III malocclusion is the sole important factor which determines the treatment option. Orthodontic camouflage is restricted to skeletal Class III patients with moderate skeletal discrepancy. In patients with severe skeletal discrepancy orthognathic surgery remains the treatment of choice because of thin alveolar housing in the lower anterior region.
The case report was prepared in accordance with the CARE guidelines for reporting case reports.
| Case Report|| |
A 19-year-old female patient reported to the Department of Orthodontics with the chief complaint of forwardly placed lower jaw.
Extraoral examination revealed hypodivergent facial pattern, concave facial profile, flat malar eminence, decreased incisal exposure, and occlusal cant during smile [Figure 1]. Intraoral examination revealed ovoid maxillary and mandibular arch, bilateral posterior and anterior crossbite, and missing 36. The patient exhibited bilateral Class III molar and canine relation with overbite of 2 mm and reverse overjet of 10 mm [Figure 2]. The lower dental midline was shifted to the right by 4 mm and the upper dental midline was shifted to the left by 2 mm with respect to the facial midline.
Based on cephalometric evaluation, the patient was diagnosed as Angle's dentoalveolar Class III malocclusion on a Class III skeletal base attributing to retrognathic maxilla and prognathic mandible on an average mandibular plane angle with anterior and posterior crossbite, proclined upper incisors, upright lower incisors, and reverse overjet [Figure 3] and [Table 1].
Following assessment of degree of skeletal malrelationship, three treatment options were considered.
Due to severity of the skeletal malocclusion, orthognathic surgery was the treatment of choice. This involved extraction of the upper first premolars to correct the compensated incisors combined with Le Fort I advancement to address the maxillary deficiency and bilateral sagittal split osteotomy (BSSO) setback to correct the prognathic mandible and advancement genioplasty to enhance the profile along with yaw and roll correction.
The second option was orthodontic camouflage by extraction of lower first premolars to retract the lower anteriors and achieve a Class I canine relation.
The third option involved en-masse distalization of the lower dentition to a Class I molar relationship using miniplates.
The drawbacks of the latter two options were that neither the upper incisor proclination would be corrected nor the maxillary deficiency would be addressed.
The patient accepted the first option which was combined orthodontic-surgical management. Degree of planned movements required was determined by surgical treatment objective and mock surgery [Figure 4].
Presurgical orthodontic decompensation involved extraction of 14 and 24, following which alignment and leveling was performed sequentially with 0.016” NiTi, 0.016” × 0.022” NiTi, 0.017” × 0.025” NiTi, and 0.019” × 0.025” NiTi archwires using 0.022” × 0.028” MBT bracket prescription. Retraction in the upper arch was performed by friction mechanics using 0.019” × 0.025” SS posted archwire which accentuated the negative overjet [Figure 5]. The maxillomandibular relationship of the patient was registered using a face bow and transferred to the SAM III articulator, and intermediate and final surgical splints were fabricated.
The surgical phase comprised Le Fort I maxillary advancement of 6 mm and BSSO setback of 7 mm with roll and yaw correction associated with advancement genioplasty of 5 mm [Figure 6]. 0.021” × 0.025” SS was used to stabilize both upper and lower arches postsurgically. After surgery, the patient had an increased incisal exposure during smile [Figure 7], which was treated using a Burstone's intrusion arch. Settling of the occlusion was done on 0.018” SS archwire with the help of settling elastics. In the retention phase, an upper Begg's wrap-around retainer was delivered and a lower lingual retainer was bonded. The treatment was completed in 20 months.
| Results|| |
At the end of treatment, the patient's smile esthetics improved and stable Class II molar occlusion on a Class I skeletal base with Class I canine relationship and normal overbite and overjet was achieved [Figure 8]. Extraorally, there was an immense improvement in the facial profile [Figure 9],[Figure 10],[Figure 11]. She had a missing 36 which would be treated using a prosthetic implant. The pre-treatment, post surgery and post treatment cephalometric values are presented in Table 1.
| Discussion|| |
The decision-making on borderline cases has been discussed by Stellzig and Kerr;, ANB angle up to a negative threshold of −4° and maxillomandibular ratio up to 0.84, Wits appraisal value of −4.76 mm, and Holdaway angle of 3.5° have been used as cephalometric parameters in deciding which cases are amenable for treatment by camouflage. The patient had an anteroposterior discrepancy of ANB=−9°, which indicates that it cannot be treated by camouflage. Treatment by camouflage entails compromising the chin profile since there is worsening of an already flattened mentolabial sulcus. This inevitably warrants surgical repositioning of the chin.
The above options for Class III camouflage were considered suboptimal for the patient as it does not address maxillary deficiency and would have resulted in compromised facial esthetics.
The ideal approach to treat the patient was surgical correction since it was the only approach that dealt with the underlying skeletal defect. Based on the stability and predictability of orthognathic surgery, maxillary advancement in combination with mandibular setback is said to be acceptably stable. Maxillary advancement of 5 mm and mandibular setback of 7 mm were performed for the patient, which was within the threshold proposed by Mucedero et al. for long-term stability.
Often, in cases where mandibular setback is planned, there is an increase in lower anterior facial height, but it is acceptable in esthetic standpoint as it improves the profile of the patient.
Extraction of upper 4s and lower 5s is required in skeletal Class III cases treated by surgery to achieve Class I molar relationship. As any cusp-fossa relationship was acceptable for long-term stability of the buccal occlusion and there was a need from the patient's perspective to reduce the number of tooth material being removed, extraction of upper 4s was considered to finish in stable Class II molar relationship.
Mild proximal stripping was required to achieve ideal incisor mandibular plane angle and lower incisor inclination as there was a mandibular tooth material excess after extraction of upper 4s. The oral hygiene maintenance by the patient was poor, and proximal stripping was not planned. Instead, the lower incisors were mildly proclined and indefinite lower incisor retention was planned.
The awareness, need, and motivation for orthodontic treatment have been proven to be higher among Class III individuals when compared with Class II individuals. This is presumed to be due to difficulties stemming from both esthetics and masticatory function. It is imperative to explain to the patient the steps involved as this aids in establishing faith and satisfying patient expectations.
| Conclusion|| |
Etiology of skeletal Class III malocclusion is multifactorial and is challenging to treat by camouflage alone. Treatment of impaired facial esthetics in adults requires careful assessment of the underlying skeletal problem and may necessitate combined orthodontic-surgical management. The proposed treatment modality must be directed toward the patient's chief complaint and also address the functional imbalance. Careful diagnosis and the skill of the surgical team involved are paramount for attaining harmonious facial esthetics and should be the primary goal of treatment.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11]