OSTEOPLASTY OF THE MAXILLA IN PATIENTS WITH UNILATERAL CLEFT LIP AND PALATE BY A MANDIBULAR BONE GRAFT WITH THE USE OF 3D COMPUTER MODELING

Abstract

Rationale: Maxillary defects in patients with unilateral cleft lip and palate are very heterogeneous. The existing methods to assess the results of osteoplasty are suboptimal. The ways to measure the volume of a defect are not truly three-dimensional; instead, they are based on the sum of the sizes of maxillary defect measured in the sections done across the alveolar process. This is a more or less precise approximation and its calculation may be time-consuming. Aim: To evaluate efficacy of osteoplasty with a mandible bone autograft in children with cleft lip and palate and to determine the optimal pre-requisites for satisfactory treatment results. Materials and methods: We examined and treated 30 patients with unilateral cleft lip and palate and maxillary defects, aged from 7 to 17 (mean age 11.2 ± 3.5 years). The following types of abnormalities were found: incomplete cleft lip, alveolar process and palate; complete cleft lip, alveolar process and palate; complete cleft lip, alveolar process and palate with partial ossification of the posterior hard palate related to previous surgeries. In all patients, the surgical intervention consisted of maxillary osteoplasty with a combination graft consisting of the cortical plate from the mandible body, shaped to the existing defect, an autologous bone chips taken from the mandible ramus, and a Bio-Oss xenograft. The patients were divided into 4 groups, depending on their age, diagnosis, defect size, and postoperative complications. Three-dimensional modeling to determine the volume of the defect was performed as follows: a geometrical model of the mandible defect was obtained based on the mirror copy of the contralateral healthy part; the volume of the defect was computed as the difference between the baseline and the mirror model. The results of the osteoplasty were assessed by Bergland and Chelsea scales, as well as by our own scales. Results: The defect volumes were in the range of 0.46 to 2.9 cm3 (mean, 1.32 ± 0.54 cm3). According to Bergland and Chelsea scales, good results of osteoplasty were obtained in 83% (25 / 30) of the cases. The regenerated bone thickness was good in 94% (28 / 30) of the patients. The edge of the foramen piriformis was well shaped in 90% (27 / 30) of them. After surgery, the volumes of the defects in the patients with incomplete cleft lip, palate and alveolar process were significantly smaller than those in the patients with complete cleft and partial ossification of the posterior hard palate (on average, by 0.8 cm3, p = 0.0071). In all cases, where cortical mandible grafts were taken, it was possible to obtain cortical blocks of the needed size, starting from the age of 7, without any risk of damage to the immature permanent teeth. Graft formation from the mandible body was not associated with any local complications in any patient. Conclusion: Our method of 3D modeling to determine the volume of mandible defects is a truly 3D approach, which allows for a highly accurate quantitative assessment of the defects. The use of the combination grafts from the mandible body and the Bio-Oss xenografts for osteoplasty helps to replace the maxillary defect irrespective of the patient's age and the defect volume. Cortical grafts can be taken from the mandible starting from the age of 7 without any risk of damage to the immature permanent teeth. Irrespective of the clinical situation, the osteoplasty results are influenced predominantly by adherence to the surgical technique and to post-operative recommendations.