The treatment objectives were to widen maxillary arch width, align dentitions, correct open bite and crossbite, adjust the relationship between the upper and lower arch ,and establish an adequate occlusion as well as facial harmony and esthetics.
Treatment alternatives
This case has both intra-arch problems, intermaxillary occlusion problems, and horizontal, vertical, and sagittal skeletal problems. Intra-arch problems like crowding could be solved by routine orthodontic treatment. Kinds of maxillary expanders are commonly used for the deficiency in maxillary transverse width.[23] As to the anterior open bite and high-angle skeletal pattern, the optimal choice is combined approach of orthodontics and orthognathic surgery.[24] However, consider of the risks and costs, the patient refused to take an orthognathic surgery. Intrusion of the posterior teeth is also effective for the close of open bite and improve high-angle skeletal pattern by the clockwise rotation of the mandible. [25]
We planned to solve the crowding problem in the dental arch by extraction firstly. Apart from three wisdom teeth, four premolars should be extracted to solve crowding. Regarding the selection of extracted teeth, since the maxillary right and mandibular left first premolars were residual crowns with large defects and the maxillary left second premolar had received root canal treatment, these teeth were firstly considered for extraction. Besides, the mandibular right second premolar was selected to extract because of the low impaction.
After the upper arch were aligned, we would deal with the horizontal problem of occlusal relationship and the width of the maxilla. Microimplant-assisted rapid palatal expansion (MARPE) would be used to enlarge the maxillary arch width since it has been considered as an effective method in adults [26]. The right posterior crossbite would be relieved at the same time with the help of intermaxillary traction and miniscrews. The vertical problem of anterior open bite would be relieved by intrude the molars by the use of miniscrews. Finally, we planned to adjust the occlusion contact by retraction of the upper anterior teeth, allocation of the remaining extraction space, and intermaxillary traction.
Treatment progress
Before the orthodontic treatment, we recommended the patient to receive the dental caries repaired and periodontal treatment including scaling, root planning, and instructions in oral hygiene to resolve gingival bleeding and inflammation. In addition, bad habit of low tongue posture needed to be corrected to avoid adverse incisors movement or recurrence.
Then nickel-titanium archwires from thin to thick (0.012, 0.014, 0.016-inch) were placed in straight-wire appliance to align the maxillary and mandibular arches. Since the impaction of maxillary right first premolar obstructed the aligning procedure, we extracted it at the beginning, and corrected the rotated second premolar by bonding buttons on both buccal and palatal sides and pulling by elastic chain. A miniscrew was struck on the palatal alveolar bone of upper right posterior tooth to correct the buccal tilt of maxillary right second molar. Springs were put between mandibular first premolar and first molar to set preliminary upright of the molars. Resin maxillary molar pads were used to level the Spee curve (Fig. 5).
After initial alignment, we used MARPE to expand the maxillary arch, and the other three premolar (maxillary left second, mandibular left first and mandibular right second) were removed to achieve an ideal Bolton ratio (Fig. 6). Three months were needed to stabilize the completed expansion, and then intramaxillary forces were used for extraction gap closing and incisor retraction.
Maxillo-mandibular elastics combined with an anteriorly placed crisscross elastic, a Class II intermaxillary elastic [27] in the left and a Class III intermaxillary elastic in the right were put to correct the midline shift. The left maxillary anchorage screw was for closing the gap as well as adjusting the midline.
Considering the poor periodontal condition of the patient and the partially exposed root of the second left premolars, an individual bends made by 0.019*0.025-in stainless steel wire was used to make the force direction closer to center of resistance during mandibular molars uprighting procedure. We also chose segmental arch technology to protect the posterior anchorage and decrease reciprocating movement (Fig. 7).
In the final stage, we bound buckles and pulled by elastic chain to correct the abnormal tip or torque of some teeth. Such devices like gate spring were also put in use. The molar relationship was further improved.
The patient’s oral hygiene was not adequately maintained, which complicated the progression of orthodontic treatment. To reduce plaque and gingival inflammation, the patient followed oral hygiene program at every visit.
The entire treatment lasted for 23 months. After removing the appliances, fixed lingual retention was placed from lateral to lateral in the maxillary arch and canine to canine in the mandibular arch. In addition, the patient was instructed to wear thermoplastic retainers all the day and came back to the hospital for a check after half a year.