SURGICAL AND ORTHODONTIC CORRECTION OF SKELETAL CLASS III MALOCCLUSION

INTRODUCTION

The condition of Class III Malocclusion is one which is rarely purely dentoalveolar in origin. Rather, it is more frequently inclusive of an aberration in the skeletal relationship of the patient’s craniofacial structures.1,2 

Skeletal class III malocclusion may either be associated with maxillary retrusions, mandibular protrusions or combination of the two.3 A careful diagnosis on the part of the Orthodontist is crucial in formulating the most suitable treatment plan for individual cases.

In growing patients, Skeletal Class III malocclusions can be dealt with by early intervention using chin cups, reverse headgears, functional appliances and fixed appliance therapy along with the use of heavy inter-arch elastics. However, if inadequate growth of the patient is remaining or if the growth has ceased altogether, Orthognathic Surgery remains the only option for obtaining a normal occlusion and an aesthetic profile.4

It has been observed that a large proportion of patients seeking Surgical- Orthodontic treatment are Class III patients.5 Proffit reported that 20% of patients at a surgical-orthodontic clinic had mandibular excesses, with 17% having maxillary deficiencies and 10% having both.6 The main objectives of surgical-orthodontic treatment are to normalize the facial profile, occlusion, and function. Correction of the main dentoskeletal parameters to within the normal range of values is usually regarded as a main aim of treatment.5

This article discusses the Surgical and Orthodontic treatment of Skeletal Class III Malocclusion in a 23-year old male patient.

EXTRAORAL FEATURES

A 23-year-old male patient presented with a concave profile, straight facial divergence, Class III relation of the apical bases, retrusive maxilla and a protrusive mandible with an average mandibular plane angle.

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Figure 1: Pre-Treatment Extraoral Photographs

INTRAORAL FEATURES

Intraoral examination revealed Angle’s Class III molar relationship and Class III Canine relationship bilaterally. Missing 15 and spacing present between 16-14, 14-13 was observed along with. Rotations with respect to 35, 33 and 43. A negative overjet of -3mm was also observed.

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Figure 2: Pre-Treatment Intraoral Photographs

CEPHALOMETRIC EXAMINATION

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Figure 2: Pre-Treatment Intraoral Photographs

The cephalometric values were suggestive of a Skeletal Class III relation of the apical bases with Retrognathic Maxilla (SNA- 77.5°), Prognathic Mandible (SNB- 81.5°) and an average growth pattern. The dentition’s cephalometric values indicated proclination in the upper incisors.
 The soft tissue values suggested a slightly increased nasolabial angle.

DIAGNOSIS

It was diagnosed to be a case of Skeletal Class III Malocclusion with a Retrognathic Maxilla and Prognathic Mandible with Anterior Crossbite and Missing 15

TREATMENT OBJECTIVES

  1. Correction of the Skeletal Maxillo-Mandibular relationship.
  2. Correction of Anterior Crossbite.
  3. Correction of Incisor proclination.
  4. Achievement of optimum aesthetics and a harmonious soft tissue profile. 

TREATMENT PLAN

A combination of Surgical and Orthodontic treatment was planned with Maxillary advancement by Le Fort I Osteotomy and Mandibular setback using Bilateral Sagittal Split Osteotomy (BSSO). Pre-surgical decompensation and a Post-surgical Orthodontic finishing and detailing with Angle’s Class I Molar Relationship on the left side and Angle’s Class II molar relationship on the right side.

TREATMENT PROGRESS

Orthodontic treatment was undertaken using MBT Prescription 0.022-inch brackets. Pre-surgical decompensation was carried out by uprighting of the mandibular and maxillary anteriors. 16 was protracted into the space of the missing 15 using mini-screw anchorage.

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Figure 3: Pre-Surgical Decompensation in progress

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Figure 4: A-Mock Le Fort I Surgery and Intermediate Cast Fabrication; B-Mock BSSO and Final Splints Fabrication

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Figure 5:Maxillary and Mandibular Final Splint

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Figure 6: A & B: Le Fort I Osteotomy with Rigid Fixation; B & C: Bilateral Sagittal Split Osteotomy (BSSO) with rigid fixation.

Post-surgery, orthodontic therapy was continued. The occlusion was settledwith the help of Class II elastics and settling elastics followed by final finishing and detailing. The case was finished with Angle’s Class II molar relationship on the right side and Angle’s Class I molar relationship on the left side and Class I Canine relationship bilaterally.

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Figure 7: Post-Treatment Settling

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Figure 8: Post-Treatment Extraoral Photographs

At the end of active treatment, retentive protocols were carried out using fixed lingual retainers from 13-23 and 33-43 and Essix Retainers for both arches.

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Figure 9: Post-Treatment Intraoral Photographs

DISCUSSION

A 23-year old male patient had presented with a chief complaint of a forwardly placed lower jaw. Clinical and Cephalometric evaluation had led to the diagnosis of a skeletal Class III relation with a retrusive maxilla and a protrusive mandible. A surgical treatment plan was chosen to correct the patient’s craniofacial disharmony.

The patient also had a missing second premolar on the right side. Excluding the third molars, the second premolars are the most common congenitally missing teeth.7 The treatment options for a congenitally missing second premolar include space creation or maintenance in order to prosthetically replace the missing tooth, maintenance and reshaping of the deciduous second molar or orthodontic space closure.8 Since the patient’s primary molar had exfoliated, orthodontic space closure by protracting the 1st permanent molar into the second premolar space was chosen. This was also advantageous as it would eliminate the need for further prosthetic rehabilitation. Further, protracting the permanent molar into the 2nd premolar space would allow a proper interdigitation of the teeth with a cusp-embrasure relationship.

However, moving the maxillary first permanent molar into the space of the second premolar would mean that the molars would end in an Angle’s Class II relation. Previously, it was believed that finishing an occlusion in a Class II molar relation would lead to Temporomandibular Joint problems and a lack of stability. However recent studies have suggested that these fears are unfounded and adequate stability exists in a Class II Molar relationship finish.9,10,11 Hence, the current treatment’s finish which was also in a Class II molar relation on the right side, would provide no complications in terms of TMJ risk or compromised stability.

Le Fort I Osteotomy in combination with Bilateral Sagittal Split Osteotomy (BSSO) provides the most useful method for improving facial contours, eliminating asymmetries, and establishing good occlusion.12 This method has been shown to be a stable mode of correction of Skeletal Class III in the short and long-term.13, 14, 15

REFERENCES

  1. Ellis III E, McNamara Jr JA. Components of adult Class III malocclusion. Journal of Oral and Maxillofacial Surgery. 1984 May 1;42(5):295-305.
  2. Guyer EC, Ellis III EE, McNamara Jr JA, Behrents RG. Components of Class III malocclusion in juveniles and adolescents. The Angle Orthodontist. 1986 Jan;56(1):7-30.
  3. Sanborn RT. Differences between the facial skeletal patterns of Class III malocclusion and normal occlusion. The Angle Orthodontist. 1955 Oct;25(4):208-22.
  4. Lin J, Gu Y. Preliminary investigation of nonsurgical treatment of severe skeletal Class III malocclusion in the permanent dentition. The angle orthodontist. 2003 Aug;73(4):401-10.
  5. Johnston C, Burden D, Kennedy D, Harradine N, Stevenson M. Class III surgical-orthodontic treatment: a cephalometric study. American journal of orthodontics and dentofacial orthopedics. 2006 Sep 1;130(3):300-9.
  6. Proffit WR, Phillips C. Who seeks surgical-orthodontic treatment? The International journal of adult orthodontics and orthognathic surgery. 1990;5(3):153-60.
  7. Symons AL, Stritzel F, Stamation J. Anomalies associated with hypodontia of the permanent lateral incisor and second premolar. Journal of Clinical Pediatric Dentistry. 1993 Jan;1;17:109.
  8. Kokich VG, Kokich VO. Congenitally missing mandibular second premolars: clinical options. American Journal of Orthodontics and Dentofacial Orthopedics. 2006 Oct 1;130(4):437-44.
  9. Janson G, Camardella LT, Araki JD, de Freitas MR, Pinzan A. Treatment stability in patients with Class II malocclusion treated with 2 maxillary premolar extractions or without extractions. American Journal of Orthodontics and Dentofacial Orthopedics. 2010 Jul 1;138(1):16-22.
  10. Janson G, Leon-Salazar V, Leon-Salazar R, Janson M, de Freitas MR. Long-term stability of Class II malocclusion treated with 2-and 4-premolar extraction protocols. American Journal of Orthodontics and Dentofacial Orthopedics. 2009 Aug 1;136(2):154-e1.
  11. Janson G, Araki J, Camardella LT. Posttreatment stability in Class II nonextraction and maxillary premolar extraction protocols. Orthodontics: The Art & Practice of Dentofacial Enhancement. 2012 Mar 1;13(1).]
  12. Ueki K, Marukawa K, Shimada M, Nakagawa K, Alam S, Yamamoto E. Maxillary stability following Le Fort I osteotomy in combination with sagittal split ramus osteotomy and intraoral vertical ramus osteotomy: a comparative study between titanium miniplate and poly-L-lactic acid plate. Journal of oral and maxillofacial surgery. 2006 Jan 1;64(1):74-80.
  13. Skoczylas LJ, Ellis III E, Fonseca RJ, Gallo WJ. Stability of simultaneous maxillary intrusion and mandibular advancement: A comparison of rigid and nonrigid fixation techniques. Journal of Oral and Maxillofacial Surgery. 1988 Dec 1;46(12):1056-64.
  14. Bothur S, Blomqvist JE, Isaksson S. Stability of Le Fort I osteotomy with advancement: a comparison of single maxillary surgery and a two-jaw procedure. Journal of oral and maxillofacial surgery. 1998 Sep 1;56(9):1029-33.
  15. Proffit WR, Phillips C, Prewitt JW, Turvey TA. Stability after surgical-orthodontic correction of skeletal Class III malocclusion. 2. Maxillary advancement. The International journal of adult orthodontics and orthognathic surgery. 1991;6(2):71-80.

 

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