Abstract
This report describes a combined orthodontic surgical technique involving vertical alveolar distraction using temporary anchorage devices (TADs) in cases of massive alveolar ridge bone and teeth loss. A combined surgical orthodontic protocol included presurgical orthodontic preparation and a preimplantation surgical augmentation stage for insertion of a vertical distractor. During the active vertical alveolar distraction process TADs were inserted. Intraoral orthodontic elastics were attached to the main orthodontic archwire exerting multidirectional forces to control the vertical distraction vector. After 3 months of vector controlling and active bone moulding, the TADs were removed. Anterior alveolar ridge augmentation using distraction osteogenesis was achieved. The application of TADs for better anterior segment curvature enabled dental implant insertion, better positioning and restoration. A combined surgical orthodontic management protocol involving vertical alveolar distraction osteogenesis for augmentation purposes is an efficient treatment method to improve alveolar ridge volume for the preimplantation stage.
During the alveolar distraction process, three dimensional (3D) vector control is a crucial factor in determining the planned movement and in maintaining precise evaluation of the desired distraction direction . Owing to the curved architecture of the maxillary and mandibular alveolar ridge, especially along the intercanine arch span, the distractor is originally angulated appropriately, but the accurate guidance of the vector’s direction is limited. Consequently alveolar ridge augmentation during distraction most often results in a straight and flat alveolar ridge structure rather than a curved one. The delicate distracted bone is also exposed to the moulding forces exerted by the surrounding soft tissue matrix. In this way the transported bone segment is forcefully pushed inward (in a palatal or lingual direction) during regular and normal function of the buccinator mechanism. It is important to identify the direction of the newly regenerated bone early enough to avoid compromising the alveolar ridge augmentation results.
Temporary anchorage devices (TADs) are fixed temporarily to the bone to enhance orthodontic anchorage and are removed after use. Their advantages, in addition to their size, include minimal anatomic limitations, minor surgery insertion, increased patient comfort, immediate loading, and low cost . As an anchorage device, this type of appliance may be inserted into a regenerated segment enabling the application of orthodontic forces to control the distraction vector, thus moulding its required form for future dental restoration.
In this article, the authors present a new technique for 3D vector control during vertical alveolar ridge augmentation using distraction osteogenesis and TADs, for better anterior ridge curvature form.
Materials and methods
Initially, preliminary orthodontic treatment is carried out to level and align the maxillary and mandibular dental arches until both arches are coordinated ( Fig. 1 ). The preimplantation surgical alveolar bone augmentation stage includes vertical distraction of the residual basal bone using an intraoral distractor (KLS Martin distractor, Tuttlington, Germany). The anterior maxillary or mandibular area is anaesthetized with 2% lidocaine and 1:100,000 epinephrine. A vestibular incision is made in the area of distraction. The incision plane maintains the vascularization of the soft tissues and consequently the bone segment to be distracted. A trapezoid osteotomy is performed using an oscillating microsaw and the distractors are attached by means of 1.5 mm micro screws. The surgical incision is sutured to cover the distractor and the exposed alveolar bone completely. Postoperatively, 500 mg of amoxicillin is prescribed 3 times a day for 7 days.
After a latency period of 5 days, a vertical distraction of the transported segment begins at a rate of 0.5 mm per day by turning the device twice a day until the desired bone height is achieved ( Fig. 2 ). During the active vertical alveolar distraction process, orthodontic implants (TADs) are inserted into the transported segment according to the desired vector orientation ( Fig. 3 A) . Intraoral orthodontic elastics are then attached from the TADs to bent loops or prefabricated crimpable hooks on the main orthodontic archwire. These are banded/attached according to the preplanned desired vector for the 3D distraction process controls. The patient continues to wear the elastics after the active distraction period for an 8-week consolidation period. Later, the vertical distraction devices are removed under local anaesthesia. Vector controlling and active bone moulding using the TADs and intraoral elastics continues for 8–10 weeks until the desired curvature of the transported alveolar segment is achieved for ideal implant positioning ( Fig. 3 B). Finally the TADs are removed and dental implants can be inserted. Good aesthetics, functioning and occlusal relationships can be achieved ( Fig. 4 ).
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