Alveolar Bone Grafting Outcome Between Patient With and Without Orthodontic Treatment

Overall goals of study:

The goals of this study are to determine whether pre-operative orthodontic treatment will affect secondary alveolar bone grafting outcome

Importance of alveolar bone grafting Alveolar bone cleft is present in the majority of patients with cleft lip and palate. This bone cleft destabilizes the maxillary arch and predisposes it to medial collapse. Teeth will not erupt in this region of alveolar bone defect. Permanent stabilization of the maxillary segments into a functional dental arch form is achieved by reconstruction of alveolar with bone grafts. The goals of alveolar bone grafting are to maintain normal occlusion and to provide a matrix for the continued eruption of permanent teeth in this region. Moreover, future maxillary expansion cannot be done unless repair of the alveolar cleft is coordinated with the desired orthodontic movement.

Timing of alveolar bone grafting Maxillary growth and dental age are the predominant considerations in determining the timing of alveolar reconstruction. Maxillary growth is completed near the age of eight years old, whereas the maxillary canine does not erupt before the age of ten.Therefore, to minimize growth disturbance to the maxilla, reconstruction should be performed after the growth is completed.It has been widely agreed that the timing of alveolar grafting should be around the stage of mixed dentition . The bone grafting should be completed at approximately nine years of age when the bulk of the alveolar bone growth is completed and the incisors are erupted, while the lateral incisors and canines are starting to erupt into alveolar cleft region

Diagnosis Radiographic studies, including panoramic radiographs, selected periapical films, Cephalographic films and recently CT scan are integral parts for diagnosis and evaluation. They provide important assessments of the pre-operative dentition in the vicinity of the cleft, the dimensions and structures of cleft itself as well as postoperative condition of the bone bridge after alveolar bone grafting.The CT scan offers more detailed pre-operative and post-operative bone structures with less distortion. Additionally, CT scan also provide: 1. Detailed information about the depth and volume of bone deposited in the cleft, 2. More consistent in showing bone trabeculation, 3. Detailed position of erupting teeth relative to the bone graft, 4. More detailed bone and teeth anatomy for clinical orthodontics decisions. In addition, the CT scan could offer 3D lineal measurements and volumetric analysis . Arai et al. developed a novel cone-bean CT (CBCT) or Ortho CT which has important characteristics such as lowered radiation dose and the ability to produce higher resolution compared to conventional spiral CT. Several reports have indicated that it is clinical useful for the 3D imaging diagnosis in the maxillofacial region.

Pre-operative orthodontic treatment The orthodontists form an integral part in the cleft care. Their recommendations regarding timing of treatment should be carefully considered before surgical treatment. The dental crowding and malposition of the teeth around the cleft can interfere with oral hygiene . The goal of the preoperative orthodontic treatment is to optimizing the position of dentoalveolar structure which enables the patients to have better oral hygiene prior to the operation. Some centers have recommended that the orthodontic treatment become part of the treatment protocol for their patients However, the presurgical orthodontics treatment is time consuming as the children are required to visit the clinic for monthly orthodontic adjustment. The average duration of the orthodontic treatments before operation is 6 months. These factors not only add discomfort to the children but also create significant financial burden to the parents. Even this primary orthodontic treatment is able to align the upper dental arch; secondary orthodontic treatment is always needed after complete permanent teeth eruption. Therefore, the actual need of presurgical orthodontics remained questionable. No studies have yet to actually address the outcome of alveolar bone grafting with or without presurgical orthodontics. The primary goal of this present prospective randomize study is to determine whether pre-operative orthodontics treatment will affect secondary alveolar bone grafting outcome.

Donor site selection:

The bones used most commonly include the iliac crest, calvarial or tibia. Regardless of the donor site, cancellous bone is preferable to cortical or osteochondral graft . The iliac crest as a donor site is preferred because it has sufficient cancellous bone to fill even a large alveolar bone defect.

Surgical procedures:

The surgical procedures of alveolar bone graft are similar to the procedures that were described by Hall and Posnick et al. except with some minor modifications. With adequate general anesthesia via orotracheal intubation, two teams worked at the same time with one team harvesting the bone graft and the other team preparing the recipient site at the oral cavity. Attention was turned to the right hip where an oblique incision was made lateral and parallel to the iliac crest. The incision was deepened to the periosteum of the lateral cortex. The iliac crest was reflected medially as a bone flap. Cancellous bone chips was harvested. At the same time, the other team was working on the oral cavity. The mouth was suctioned and a throat pack was placed. The gingiva and upper buccal sulcus were infiltrated with 1% Xylocaine in 1:200,000 epinephrine solutions for hemostasis and easier dissection. Incisions were made along each side of the alveolar cleft. A superiorly based gingival mucoperiosteal flap was designed and raised sharply from the gingival margin on the lesser segment. The flap was extended posteriorly to the first molar. The incision was then curved up obliquely towards the buccal sulcus. The flap on the medial segment was elevated in a similar fashion towards the midline. The palatal mucoperiosteal flaps were raised to a level beyond the deepest margin of the alveolar fistula. The fistula margins at the palatal side were freshened and sutured. The nasal floor tissue could be completely separated from the palatal mucoperiosteum after raising the palatal flaps and could then be stripped off the bony cleft. The nasal floor tissue was dissected upward reaching the pyriform aperture on the lateral segment and the cartilaginous septum on the medial segment. This allowed a tension-free closure of nasal floor tissue and adequate correction of the vertical discrepancy of the nostril sill. The nasal floor fistula was securely repaired with 4-0 Vicryl sutures. Cancellous bone chips which were already harvested from iliac bone by another team were packed firmly into the bony defect to the level of the alveolar process and the pyriform aperture on the cleft side. The periosteum of the lateral gingival flap was scored to reduce the tension especially at the lateral end of the incision. The lateral gingival flap was then advanced and sutured to the medial flap and palatal flap to provide a watertight and tension free closure.