This case report describes the orthodontic retreatment a patient with a skeletal Class III malocclusion. The clinical examination showed a concave profile caused by a retruded maxilla and a prognathic mandible, an occlusal cant, and absence of all first premolars. A surgery-first approach was combined with skeletal anchorage implants in the maxillary arch and tandem mechanics. The esthetic facial profile, pleasant smile, appropriate occlusion, and overall good treatment outcomes remained stable 5 years after active orthodontic treatment.
Highlights
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A skeletal Class III malocclusion was treated with surgery, skeletal anchorage, tandem mechanics.
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Surgery-first approach produces rapid profile improvement.
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Tandem mechanics supported by skeletal anchorage reduce total treatment time.
Recently, surgery-first orthognathic treatment followed by orthodontics to align, level, and stabilize the occlusion has raised noticeable interest because this approach corrects the skeletal problem from the beginning, promotes rapid improvement in facial esthetics, produces psychosocial benefits, and greatly reduces the treatment time.
The following primary indications have been proposed for the surgery-first approach: (1) moderate or minimal crowding and adequate inclination of mandibular anterior teeth, (2) at least 3 stable occlusal stops between the maxillary and mandibular arches, (3) little or no transverse discrepancy, and (4) an adequate curve of Spee.
In addition, with the aid of a skeletal anchorage, the arch length can be increased by postsurgical distalization of the posterior teeth to accommodate crowded teeth and still achieve proper axial incisor inclinations. This temporary device enables predictable 3-dimensional movement of the entire dentition in nongrowing patients, thereby widening the primary indications for the surgery-first approach. In compliance with these principles, we adapted tandem mechanics to be supported by a skeletal anchorage.
The tandem approach for intraoral distalization, originally described by Haas, is traditionally a mechanics system anchored by cervical headgear. This biomechanical strategy involves selective deployment and use of mechanical forces to simultaneously initiate various groups of tooth movements in both dental arches.
This article describes the surgery-first approach combined with the skeletal anchorage mechanics to treat a patient with a skeletal Class III malocclusion. The treatment included tandem mechanics for mandibular molar distalization, and it resulted in improved esthetics and occlusal stability in a 5-year follow-up. See Supplemental Materials for a short video presentation about this study.
Diagnosis and etiology
A male patient, aged 17 years, came for orthodontic treatment with the chief complaint of the appearance of his teeth; he wanted to improve his face. He reported that he had undergone a 3-year orthodontic treatment 3 years earlier. The facial photographs showed proportional facial thirds, a concave profile, a deficient smile, and an occlusal cant. The upper lip was retruded 4 mm and the lower lip 2 mm in relation to the S line. The intraoral photographs and dental casts showed complete Class III molar and canine relationships, −2-mm overjet, edge-to-edge overbite, and 2-mm deviation of the maxillary midline to the left side. Compensations in the mandibular arch were accompanied by crowding and a tooth-size discrepancy of −5 mm ( Figs 1 and 2 ).
The cephalometric analysis showed a Class III jaw-base relationship (ANB angle, −4°; Wits appraisal, −10 mm). The maxillary incisors were buccally tipped and protruded; the mandibular incisors were retruded (1:NA, 8 mm and 35°; 1:NB, 4 mm and 15°; IMPA, 77°). Considering the values of the occlusal plane angle (Occl:SN, 11°), mandibular plane (GoGn:SN, 33°), and y-axis (y-axis to FH, 56°), a predominantly horizontal growth pattern was inferred. The McNamara analysis showed maxillary retrusion in relation to the cranial base (Co-A, 88 mm; A-NPerp, −4 mm), mandibular protrusion in relation to the cranial base (Co-Gn, 135 mm; Pog-Nperp, 10 mm), as well as a remarkable maxillomandibular discrepancy: Co-A–Co-Gn, 47 mm, when the normal range is 30 to 33 mm. The panoramic radiograph showed all teeth, except that the 4 first premolars were absent ( Fig 3 ; Table ).
| Measurement | Norm | Pretreatment | Posttreatment |
|---|---|---|---|
| SNA (°) | 82 | 79 | 82 |
| SNB (°) | 80 | 83 | 82 |
| ANB (°) | 2 | −4 | 0 |
| 1-NA (mm) | 4 | 8 | 7 |
| 1:NA (°) | 22 | 35 | 25 |
| 1-NB (mm) | 4 | 4 | 4.5 |
| 1:NB (°) | 25 | 15 | 20 |
| 1:1 (°) | 131 | 130 | 131 |
| Occl:SN (°) | 14 | 11 | 12 |
| GoGn.SN (°) | 32 | 33 | 37 |
| S-LS (mm) | 0 | −4 | 0 |
| S-LI (mm) | 0 | −2 | −1 |
| Y-axis to FH (°) | 59.4 | 56 | 54 |
| NPog.FH (°) | 87.8 | 93 | 95 |
| Angle of convexity (°) | 0 | −14 | −7 |
| Wits (mm) | −1.17 | −10 | −1.5 |
| FMA (°) | 25 | 27 | 28 |
| FMIA (°) | 65 | 76 | 74 |
| IMPA (°) | 90 | 77 | 78 |
| Nasolabial angle (°) | 102 | 100 | 95 |
| A-NPerp (mm) | −1 | −4 | 3 |
| Co-A (mm) | 88 | 94 | |
| Co-Gn (mm) | 135 | 135 | |
| AIFH (mm) | 76 | 78 | |
| Pog-NPerp (mm) | −2 a 2 | 10 | 13 |
Treatment objectives
The treatment objectives were to (1) correct the maxillomandibular discrepancy to obtain a normal occlusion, (2) resolve crowding in the mandibular arch, (3) achieve ideal overjet and overbite, (4) correct the maxillary midline deviation, (5) improve function, and (6) improve facial esthetics.
Treatment objectives
The treatment objectives were to (1) correct the maxillomandibular discrepancy to obtain a normal occlusion, (2) resolve crowding in the mandibular arch, (3) achieve ideal overjet and overbite, (4) correct the maxillary midline deviation, (5) improve function, and (6) improve facial esthetics.
Treatment alternatives
Analysis of the occlusion, cephalometric findings, facial analysis, and dental casts were determinants for surgical correction to achieve optimal esthetic and functional results. The following alternatives were presented to the patient.
- 1.
Conventional surgery approach. Since the premolars had been previously extracted, extractions to solve crowding in the mandibular arch followed by orthognathic surgery to obtain normal occlusion were contraindicated. Notwithstanding, the teeth could still be moved with skeletal anchorage into ideal positions in relation to their respective bones before surgery. However, this is a time-consuming process, requires additional surgery for placement of plates before orthognathic surgery, and worsens the deformity in the presurgical period, all of which were unacceptable to the patient.
- 2.
Surgery-first approach combined with skeletal anchorage orthodontic treatment. Cephalometric analysis, dental cast predictions, and simulation on profile images of the patient surgically treated on software (Dolphin Imaging and Mangement Solutions, Chatsworth, Calif) were used for treatment planning. The cephalometric analysis and the Wits appraisal indicated the need for a segmented LeFort I maxillary osteotomy with 7 mm of advancement and bilateral sagittal split osteotomies for correction of the occlusal plane. Since the patient already had received orthodontic treatment, he was concerned about undergoing it again, and he chose the surgery-first approach as a treatment option because it addressed his chief complaints while minimizing the time with fixed orthodontic appliances.
All third molars were extracted to facilitate distal movement of the posterior teeth, allowing decompensation of the mandibular incisors followed by retroclination of the maxillary incisors. A transpalatal bar was manufactured to control the maxillary arch transverse dimension.
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