DISCUSSION
Cleft lip and palate is considered the most prevalent congenital craniofacial birth defect and is the second most common congenital malformation of the human body, second only to clubfoot.15 Fusion of several structures and processes of the neonatal face result in development of both the lip and palate between the 4th to 12th week of gestation. A failure of fusion due to genetic or environmental causes may lead to the development of cleft lip and palate.16
ABG forms a fundamental component of the treatment protocol of alveolar clefts in patients with cleft lip and palate. The main objectives of ABG are to: establish continuity of the dental arch, facilitate closure of oro-nasal fistulae, correction of the nasal alar bases and to provide solid bone for tooth migration and dental implant placement. Although its use has increased, certain aspects of the surgical technique are shrouded in controversy.5 The timing at which ABG is performed is one such dilemma with two possible approaches having been proposed: primary bone grafting during infancy or secondary bone grafting during the mixed dentition period.17Recently, some consensus seems to have been reached with most surgeons opting for secondary ABG between 8 to 10 years of age due to lower incidences of complications such as maxillary growth restriction which have been reported frequently after primary ABG.9,18However, the current debate revolves around the choice of ideal source of bone graft material which may be even more controversial than the timing issue of ABG.
The ideal bone graft sites can be grouped into either extra-oral sites such as the iliac crest, proximal tibia and ribs or intra-oral sites such as the mandibular symphysis and mandibular ramus.5 The selection of a particular donor site is dependent upon the size of the defect being repaired, ease of harvest, donor site morbidity and the experience and preference of the surgeon.11 The various donor sites also provide the surgeon with a choice of either endochondral cancellous bone (extra-oral sites) or intramembranous cortico-cancellous bone (intra-oral sites).9 For many years it has been believed that endochondral bone is far more superior to intramembranous bone.9,11 However, due to the increased cortical bone content in intramembranous bone harvested from intra-oral sites, it undergoes delayed resorption and therefore maintains its volume for a prolonged period of time compared to endochondral bone.14 Additionally, intramembranous grafts have shown to develop up to 166% more new bone around the graft site, which is significantly higher than endochondral grafts.12
The maxillary tuberosity contains an appreciable amount of intramembranous bone which can be used to reconstruct small to medium alveolar clefts. After careful patient assessment, the amount of bone obtained can be enhanced further by also harvesting bone from odontectomy sites of the wisdom molars. If all these sites are utilized, there is a potential of harvesting up to 30 cc of bone, which can satisfy extensive grafting requirements.19 Other salient advantages of using these sites as a source of bone graft lies in their convenient anatomical location, a single surgical site in the same region of the body as opposed to two sites away from one another, minimal post-operative complications, hidden scars and a much shorter hospital stay.5
We therefore strongly recommend that clinical examination of these regions be a part of the routine evaluation of patients when selecting a donor site for ABG.13 During pre-operative assessment, Cone Beam Computed Tomography (CBCT) can be implemented to make an accurate 3-dimensional analysis of the maxilla and mandible for the best sites of bone graft material. Additionally, the timing of removal of the wisdom teeth should ideally coincide with repair of the clefts. It seems that the use of these sites can be a simple and valuable alternative technique for alveolar cleft reconstruction with fewer intraoperative difficulties and post-operative complications. In the event that the maxillary antrum is exposed during bone harvesting, primary immediate repair can be done.19 Since some of these patients present after having undergone unsuccessful repair of oro-nasal fistulae, advancement of local flaps to close the defects will not be successful. A well designed pedicled tongue flap is the best alternative for soft tissue repair of such defects.
In the present case, ABG was successful based on the clinical and radiographic findings (figure 6). There was establishment of good maxillary arch form with stabilization of the premaxillary segment. There was also complete closure of oro-nasal fistulae, significant improvement in the patient’s occlusion and facial profile. Overall, a satisfactory aesthetic outcome was achieved.