This case report illustrates the successful nonsurgical treatment of an adult with a skeletal Class III malocclusion exacerbated by a functional anterior shift that resulted in a severe overclosure of the mandible and a reverse smile line. To maximize the soft tissue and smile esthetics while idealizing the occlusion, active clockwise rotation of the mandible was induced along with mandibular molar uprighting and sequential leveling. In the maxilla, full arch distalization was achieved after second molar extraction. The treatment provided a satisfying esthetic and functional outcome and has remained stable.
Highlights
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An adult with Class III malocclusion, functional shift, and reverse smile was treated.
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Nonsurgical nonpremolar extraction camouflage treatment is illustrated.
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Clockwise mandibular rotation through molar uprighting improved facial balance and occlusion.
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Sequential and segmental alignment improved the smile esthetics.
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Strategic second molar extraction reduced maxillary incisor proclination.
Skeletal Class III malocclusion is defined by the sagittal relationship of the maxilla-mandibular complex, and often, it is associated with complex problems, including functional shifts due to incisal interferences. Clinically, when interference is present during intercuspation, the mandible may slide forward to avoid the premature contact, resulting in a greater negative overjet of the incisors and a decrease in apparent anterior face height. An anterior functional shift in younger growing patients has been identified as a major indication for orthodontic care, including early treatment of the skeletal deformity. Less emphasis has been placed on the esthetic consequences of overclosure of the mandible in Class III nongrowing patients. Overclosure of the mandible exacerbates the Class III malocclusion and negatively affects the facial profile. In addition, the increased overbite and reverse overjet create an unaesthetic reverse smile arc of the prominently displayed mandibular incisors.
For nongrowing adults, orthodontic camouflage treatment often includes proclination of the maxillary incisors and retroclination of the mandibular incisors. These dental changes can improve the overall occlusion yet worsen the profile by increasing apparent chin projection and negatively affecting smile esthetics.
Successful dental camouflage in adult Class III hypodivergent patients often requires active clockwise rotation of the mandible in order to improve the facial convexity and chin prominence as well as occlusal relationship. , Here, we illustrate the successful nonsurgical camouflage treatment of an adult patient with skeletal Class III malocclusion, with mandibular overclosure combined with anterior functional shift and reverse smile. Clockwise rotation of the mandible, along with the use of palatal miniscrews and intermaxillary elastic traction, helped produce a profile, smile, and occlusal improvements.
Diagnosis and etiology
A 17-year-old woman came to the Department of Orthodontics at Gangnam Severance Hospital, Yonsei University, with chief concerns of crossbite and crowding.
The initial extraoral evaluation indicated euryprosopic (brachyfacial) facial features (facial index 74) with chin prominence, concave profile, and mandibular incisal display at full smile (reverse smile). The intraoral exam indicated anterior crossbite with negative overjet (–1.5 mm) and overbite (–4.5 mm), Class III molar and canine relationships, with moderate mandibular crowding. The maxillary second molars were tipped buccally and distally, and the maxillary dental midline deviated to the left ( Figs 1 and 2 ).
The cephalometric analysis showed a skeletal Class III malocclusion (ANB, –3.4°; Wits appraisal –11.2) with a protrusive mandible (mandibular body length, 78.3 mm). Dental compensation was observed with labioversion of the maxillary incisors (U1 to SN, 115.9°) and retroclination of the mandibular (IMPA, 72.4°), along with a deep curve of Spee ( Table ). Her cervical vertebral maturity index was 6. All 4 third molars were fully developed but impacted ( Fig 3 ).
| Measurement | Norm | Initial | Progress | Final |
|---|---|---|---|---|
| Skeletal | ||||
| SNA (°) | 81.6 | 86.3 | 86.3 | 86.4 |
| SNB (°) | 79.1 | 89.7 | 86.4 | 87.7 |
| ANB (°) | 2.4 | –3.4 | –1.1 | –1.3 |
| Ramal height (mm) | 51.6 | 51.6 | 51.5 | 51.6 |
| Mandibular body length (mm) | 76.0 | 78.3 | 78.3 | 78.2 |
| SN to MP (°) | 33.0 | 34.4 | 37.13 | 35.8 |
| Gonial angle (°) | 118.6 | 131.1 | 131.1 | 133.6 |
| Facial height ratio | 60.0 | 65.0 | 63.7 | 64.3 |
| Dental | ||||
| U1 to SN (°) | 106.0 | 115.9 | 115.9 | 118.5 |
| IMPA (°) | 95.9 | 72.4 | 72.4 | 75.9 |
| Wits appraisal (mm) | –2.7 | –11.2 | –7.7 | –7.8 |
| Soft tissue | ||||
| Upper lip to E-line (mm) | –0.8 | –3.7 | –4.0 | –0.8 |
| Lower lip to E-line (mm) | 0.5 | 2.4 | 1.6 | 1.2 |
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