Anterior crossbite correction in early mixed dentition stage using functional jaw orthopedics principles: a case report with two-years follow-up

Abstract

A five-year-old and four-month-old male patient presented with Class I malocclusion, anterior crossbite (pseudo-class III) with an overbite, midline deviation to the left (5 mm), left unilateral chewing preference, and incisors in bi-retrusion with diastemas. Initial Bimler cephalometry showed negative anterior face angle (< A), negative bone overjet (A’B’), mesoprosope biotype, negative suborbital facial index, microrhinic dysplasia, and reduced T-TM distance. Pre-treatment gnathostatic models revealed vertical asymmetry and increased left occlusal plane. After the initial assessment, we initiated the treatment with resin-composite planas direct tracks in the deciduous upper molar surface to lift the bite. The patient was oriented to perform right-side mastication movements using hyperboloid exercises. After one month, a new resin-composite lift was carried out in the lower deciduous molar occlusion surface. Planas direct tracks were built directly on the occlusal of the maxillary molars 64 and 65 to start centering the patient’s midline, which was deviated to the left, raising the bite, and increasing the vertical dimension. In the same dental appointment, we completed the right side on the occlusal of the teeth 54 and 55, to adjust the occlusion using 200 microns articulated paper. After a month, the patient returned to the dental office and resins were placed in the occlusal surface of teeth 74, 75, 84, and 85, completing the direct planas tracks and leaving the occlusal plane the most parallel to the Camper’s Plan. Direct planas tracks’ adjustments were made throughout the patient's treatment returns, with 200 microns articulated paper and selective wear. Hyperboloid (silicone-made accessory to stimulate the stomatognathic system) was used to perform chewing exercises on the right side and instructed to be performed before the main meals, for five minutes, encouraging chewing on the right side. The subsequent masticatory evaluation showed protrusive movements. To reduce this movement, planas direct tracks from canine-to-canine were prepared, correcting the anterior bite, and reducing the midline deviation to the left. Posteriorly, functional orthopedic treatment began with the Simões Network 3 (SN3) device, with Bimler’s upper dental arch not touching the incisors and an upper expander. Concomitantly, in the lower dental arch, we initiated the treatment with a Hawley dental appliance against the cervical third of lower incisors and a W-shaped lingual retainer. The SN3 device was built in a laboratory specialized in maxillary functional orthopedics, after molding the patient with alginate and wax bite registration. After 12 months of treatment, the patient presented a centralized midline, had permanent lower incisors, erupting upper central incisors, and adequate bilateral chewing. After 24 months of treatment, the patient presented physiological limits with the contact of the upper central incisors in a determined area with 2 mm overjet, centralized midline, efficient bilateral chewing, and balanced maxillomandibular growth. Post-treatment Bimler cephalometry showed a negative anterior face angle (< A), positive bone overjet (A’B’), mesoprosope biotype, increased T-TM distance. In addition, Planas’ gnathostatic models evidenced a symmetric occlusal plane. In conclusion, functional jaw orthopedics approaches can significantly contribute to the inhibitory and excitatory stimulation of the mandible to the maxilla. Furthermore, functional orthopedics might establish an appropriate development of the stomatognathic system in patients with mixed dentition.