Dr. Goldreich > Publications
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| Introduction Class III skeletal malocclusions often present difficult challenges for orthodontic diagnosis and treatment planning. The timing of treatment presents a unique challenge in these individuals since the mandible enlarges the most during adolescence (1). This leaves us with a dilemma. Do we treat with a dental camouflage, utilizing extractions and/or growth modification appliances to hide the skeletal problem, or do we wait until growth is complete and use a combined surgical-orthodontic approach (2, 3)? The case below presents some of the challenges of treating a moderate Class III malocclusion in a growing patient. Case Report Diagnosis This patient presented at the age of 13 years 9 months with a chief complaint of, "I want braces to straighten my teeth." She was post-pubertal and suffered from seasonal allergies; otherwise her medical history was non-contributory. There was no history of a Class III malocclusion in her family. Her dental hygiene was poor, however her periodontal health was good and her TMJs were asymptomatic. Her frontal examination revealed symmetrical development on both sides of the face, a mid-face deficiency, mild lip incompetence, a long lower face height, the maxillary dental midline to the right of her face and no gingival display upon smiling. From a profile perspective she was midface deficient with an obtuse naso-labial angle and a deficient chin (Figs. 1-3). Intraorally, her occlusion was Class III molars, end-on Class II canine on the right side and Class III canine on the left side with a constricted upper arch form and a bilateral posterior crossbite. Maxillary laterals were also in crossbite, there was a posterior left open bite, both maxillary and mandibular arches were crowded with –12 mm and –6 mm of crowding respectively, and the maxillary canines were blocked out. The lower arch exhibited an excessive curve of Wilson and a moderate curve of Spee. She had minimal overbite (0.5 mm) and minimal overjet (0.5 mm) (Figs. 4-8). Cephalometrically she had a Class III skeletal relationship due to a retrusive maxilla. She also had a steep mandibular plane angle with a counterclockwise rotation of the occlusal plane and retroclined mandibular incisors. There was very little hard tissue chin development (Fig. 9). The panoramic radiograph revealed normal development of the dentition with a retained mandibular left primary second molar and a maxillary right primary second molar, convergent roots of the mandibular incisors, blocked out maxillary canines and unerupted developing third molars (Fig. 10). |
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| Treatment options The dilemma in treating Class III patients at her age is the unpredictability of whether the Class III malocclusion will continue to progress until the age of 16 or 17 (1), which may require orthognathic surgery to correct. However, this patient felt very self-conscious about her appearance at this time and was entering into an important social stage of her life. Therefore, there were several different treatment options in this case. A non-extraction, surgical approach might be considered with expansion of the maxilla and a future maxillary advancement, and mandibular setback surgery with a possible advancement genioplasty. An extraction with surgery option would be to expand the maxillary arch, remove the upper first premolars and the lower second premolars, with a future orthognathic surgery to advance the maxilla (3). Or a non-surgical, extraction approach whereby the maxilla is expanded and a reverse pull headgear used to advance the maxilla and attempt to reduce mandibular growth and remove two mandibular first premolars to alleviate the crowding and camouflage the Class III skeletal discrepancy (2, 4). This would result in a Class I canine and a Class III molar relationship. All options were presented, however, the parents were not willing to consent to a surgical treatment option and the patient was anxious to begin treatment. Considering her age, her skeletal maturation and her desire for treatment, it was decided that the non-surgical treatment approach would be initiated. Parents and patient were counseled about the possibility of latent mandibular growth which could require orthognathic surgery to correct. Treatment Treatment was initiated with a palatal expander to widen the upper arch and a reverse pull headgear (facemask) was used as the maxilla was widened. The expander was turned two times a day for 3 weeks (10 mm) and it was requested that the facemask be worn for 12 hours per day. After expansion was complete, the patient was referred to have the lower first premolars removed. The upper arch brackets were placed and a compressed coil spring was used to open space for the upper right lateral. A lower lingual holding arch was utilized to maintain the molar position while the lower canines were retracted. A hook was soldered to the holding arch mesial to the molars, a button was bonded to the lingual of the canines and an elastic chain was used to retract the canines. The remaining brackets were placed after the lower canines were retracted. The expander was removed 11 months after the turning was complete. Class II and triangle elastics were worn to achieve a Class I canine relationship. The lingual cusps of the upper second premolars were equilibrated, the upper archwire was sectioned distal to the canines and posterior zig-zag squeeze elastics were worn for 3 weeks to achieve maximum intercuspation. The total treatment time was 38 months. Results Achieved Better compliance with the facemask may have resulted in some protraction of the maxilla, however, a favorable Class I canine mutually protected occlusion was achieved. This was accomplished by good elastic wear and minimal forward growth of the mandible. The slight retraction of the lower incisors and the slight increase in the bony chin projection facilitated a favorable change in the profile (Figs. 11-21). Permanent upper and lower canine to canine retainers are being used which are bonded to each tooth to prevent any relapse. A full coverage slip cover retainer is also being used on the upper arch to prevent any further eruption of the upper second molars until the lower third molars erupt. Unfortunately, there were some areas of decalcification due to poor oral hygiene. However, the results were very satisfying due to the great result achieved without orthognathic surgery. Final Evaluation There are many situations which ideally would be treated with a combined orthognathic surgery and orthodontic approach, but circumstances often prohibit using surgery to correct the skeletal problem. When surgery is not an option, it is important to carefully control the mechanics, understand the potential for aberrant growth and clearly explain to the patient the necessity for cooperation and all the risks and benefits of the chosen treatment. References
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