The management of post-traumatic malocclusions is difficult, and often requires a coordinated effort on the part of several dental specialists, and occasionally, novel treatment approaches. The increasing popularity and availability of temporary anchorage devices has enabled the resolution of complex clinical situations that would otherwise have involved a compromised approach and a less than ideal treatment outcome.
History
A 16-year-old female patient presented to the Dental Clinic, Sick Kids Hospital, Toronto, on consultation regarding the protrusion of her upper front teeth and her facial asymmetry. The patient had previously undergone a 2.5-year long course of fixed appliance orthodontic treatment with the extraction of the maxillary and mandibular first premolars and third molars.
As part of the clinical history, the patient recounted that the lower jaw asymmetry was a relatively new aspect to her occlusal problems. While overseas on holiday, and while wearing orthodontic appliances, she suffered a fainting episode and struck her lower jaw on a cement pathway. According to the patient she had been assessed at a local hospital, but had been advised that no significant jaw injury had been sustained and that no treatment was required.
Clinical examination revealed a Class II, division 1 malocclusion characterized by a retrognathic mandible with deviation of the chin point to the right, overjet of 8mm, overbite of 20%, a 2.5mm shift anteriorly and to the left from centric relation to habitual occlusion, a mild maxillary occlusal plane cant (up on the right side), and severely proclined maxillary incisors (Fig. 1).
The radiographic survey revealed that the aforementioned fall had likely resulted in a right mandibular condylar neck fracture (Fig. 2). The condylar head had become displaced antero-medially, typical and consistent with the pull of the lateral pterygoid muscle, resulting in foreshortening of the right mandibular ramus, and in the clinically evident mandibular asymmetry. Since no earlier diagnostic records were available, the maxillary occlusal plane cant was assumed to represent a gradual compensatory response to the mandibular asymmetry.
Treatment Progress
The treatment recommendations included a period of pre-surgical orthodontic therapy to level and align the teeth and upright them over the supporting skeletal bone.
In order to correct the extreme proclination of the maxillary incisors, anchorage provided by a palatal implant (Straumann Orthosystem, Burlington, ON) placed midsagittally, was utilized to initially distalize the four maxillary molars and eventually to retract the premolars and incisors en masse into the space created through the molar distalization (Figs. 3-4).
At the conclusion of pre-surgical orthodontic treatment (Fig. 5) the patient underwent a maxillary Le Fort I osteotomy for correction of the occlusal plane cant and a mandibular bilateral sagittal split osteotomy to advance the mandible asymmetrically and achieve coincident dental and skeletal midlines, while correcting the significant mandibular shift (Fig. 6). The orthodontic appliances were removed five months later.
The patient was given a maxillary Hawley retainer and a mandibular bonded lingual retainer. Following 3-4 months of posterior settling, a maxillary Essix retainer was constructed for daytime wear, while the patient was requested to continue to wear the maxillary Hawley during the night.
Conclusion
The complicating features of this case not only included the unman-aged condylar neck fracture and resultant mandibular asymmetry, but that the patient presented with severe residual proclination of the maxillary incisors despite first premolar extractions and prior orthodontic treatment. In addition the maxillary incisors exhibited moderate external apical root resorption.
Without the availability of implant-derived orthodontic anchorage the only remaining options would have included either additional extractions or a segmental maxillary osteotomy, both of which would be less desirable. The anchorage device allowed for en masse distalization of the maxillary molars followed by en masse retraction of the remaining maxillary dentition. This, in turn, permitted ideal de-compensation and uprighting of the maxillary incisors in preparation for the orthognathic surgical correction. The implant was removed at the time of the definitive orthognathic surgery, and therefore did not require an additional surgical procedure. Finally, no radiographic evidence of additional root resorption was seen at the completion of treatment.
oh
Iain A. Nish Is Staff Oral/ Maxillofacial Surgeon, SickKids Department of Dentistry and is in private practice, Whitby, ON.
John Daskalogiannakis is Staff Orthodontist, Sick Kids Department of Dentistry; Assistant Professor, University of Toronto. He maintains a private practice in Scarborough, ON.
Oral Health welcomes this original article.
———
The patient recounted that the lower jaw asymmetry was a relatively new aspect to her occlusal problems
———
Without the availability of implant-derived orthodontic anchorage the only remaining options would have included either additional extractions or a segmental maxillary osteotomy
