Severe bimaxillary dento-alveolar proclination with hyperdivergent jaw bases treated with temporary anchorage devices: a case report

Diagnosis

A 19-year-old female attended the orthodontic clinic complaining of forwardly placed upper and lower front teeth, spacing in between the upper front two teeth and difficulty in lip closure. Her medical history was non-relevant and temporomandibular joint function was normal.

Extra-oral examination revealed a convex profile, incompetent lips with reduced philtrum length and increased lower anterior face height. On smiling, the patient exhibited a consonant smile arc (Figure 1). In Sarver's classification of smile lines, this means that the lower lip vermilion border follows the incisal edges of the upper teeth in a frontal smile.

Intra-oral examination showed a bilateral Angle's Class I molar and canine relationship with a midline diastema in the upper arch and moderate crowding in the lower arch with a 90° rotation of the lower left second premolar. The overjet and overbite measured 1.2 mm and 2 mm, respectively. The skeletal midline matched the dental midline (Figure 2).

The panoramic radiograph revealed a full complement of teeth except for the third molars (Figure 3).

Cephalometric analysis (Table 1) (Figure 4) showed a severe bimaxillary dento-alveolar proclination and severely protrusive incisors.

The patient was diagnosed as Angle's Class I malocclusion with severe bimaxillary dento-alveolar proclination and severely hyperdivergent jaw bases.

Treatment objectives

Treatment alternatives

Treatment progress

After the formal consent of the patient was obtained, all first premolars were extracted under local anaesthesia. The first molars were banded and the remaining teeth were bonded with a 0.022” Pre-Adjusted Edgewise Appliance (MBT prescription, 3M Unitek, Monrovia, California, USA). Initial levelling in both arches was accomplished with 0.016” NiTi (Orthoforce G4-Nickel Titanium G&H Wire Company, Hanover, Germany) archwires. The severely rotated lower left second premolar was addressed individually by placement of a couple force to correct the rotation. As soon as the rotation was corrected, 0.018” SS wires were placed in the upper and lower arches. No active retraction was undertaken during the levelling and aligning stage. Once levelling and aligning was achieved, however, 0.021” x.025” SS wires were placed in the upper and lower arches with cuspid hooks. TADs, 1.2 x 8 mm in dimension (SK Surgicals®, Pune, India), were placed in the inter-radicular area of second premolar and first molars in all the four quadrants under a topical anaesthetic (Figure 5). Implants were loaded immediately without a waiting period. Using power chains, approximately 200 gm of force was applied, running from the hooks on the continuous archwires to the head of the implant. After seven months of active en masse retraction, settling of the occlusion was completed using 0.016” SS archwires in the upper and lower arches, with settling elastics, for a period of three months. Some space was maintained mesial to the upper right canine as the upper right lateral incisor was smaller in size than the norm. After debonding the appliance, the lateral incisor was built up with hybrid Bis-GMA composite resin to match the contralateral lateral incisor.

Thirteen months after the initial bracket placement, the promulgated objectives seemed to be achieved. A good Class I molar relationship was maintained along with a Class I canine relationship with the correct overjet and overbite (Figure 6). Extra-oral photographs showed a pleasing profile (Figure 7). Cephalometric analysis and superimposition (Figure 8) revealed that the hyperdivergency of the jaw bases improved from SN-GoGn 40° to 36°; FH-GoMe, 38° to 32°, MM angle from 36° to 28°, Jarabak ratio from 58.65% to 62% (Figure 9). A post-treatment panoramic radiograph confirmed complete space closure in the premolar and canine areas (Figure 10).

The retention regime of the patient was implemented by instructing the patient to wear a maxillary and mandibular full wraparound Begg retainer for 24 hours a day for 2 years, followed by night-time only for another 6 months (Figure 11).

Discussion

The utilization of implant anchorage has proved to have many striking features and advantages:¹⁵

In the present case, high pull headgear with TPA was one of the alternate treatment options; the motive for using high pull headgear was to conserve anchorage and also to intrude the molars, however, the patient refused this option. The second alternative was to submit the patient to orthognathic surgery with the associated morbidity. The patient refused the second alternative treatment option as well. Therefore, TADs offered the best non-compliant, minimally invasive, cost-benefit effective treatment alternative and offered an effective therapy for the severe bimaxillary protrusion and hyperdivergence.

The patient's complaints, which included forwardly placed upper and lower front teeth and difficulty of lip closure, were addressed very well by this treatment modality. Since the bimaxillary proclination was corrected by complete retraction of the upper and lower anterior teeth, the upper lip assumed a more relaxed inferior position. Along with the abovementioned correction, TADs also brought about good vertical molar control.

Conclusion

In conclusion, an adult critical anchorage case of severe bimaxillary protrusion was successfully treated utilizing TADs for anchorage. TADs were used as an alternative treatment to headgear or orthognathic surgery, resulting in good occlusion with a Class I molar and canine relationship. The present case indicated that the skeletal anchorage is of great importance in achieving formulated objectives in the hitherto complex maximum anchorage scenario.