Choong-Kook Yi

The efficacy of postoperative prophylactic antibiotics in orthognathic surgery: a prospective study in Le Fort I osteotomy and bilateral intraoral vertical ramus osteotomy.

Purpose This study examined the efficacy of the postoperative prophylactic antibiotics used in orthognathic surgery. The prevalence of surgical site infections (SSIs) was determined according to the use of postoperative prophylactic antibiotics. Patients and Methods Fifty-six patients were divided into 2 groups. Each patient intravenously received 1.0 g of a third-generation cephalosporin (Cefpiramide) 30 minutes before surgery. Among them, 28 patients in the control group received 1.0 g Cefpiramide twice daily until the third day after surgery. The postoperative wounds were examined regularly for the presence of infectious signs. Results There was no significant difference in the incidence of postoperative wound infections between patients who had received postoperative prophylactic antibiotic administration and those who had not (p = 0.639). Conclusion Prolonged prophylactic antibiotic use after orthognathic surgery may not be necessary, provided that there are no other significant factors for wound infections.

Architectural characteristics of the normal and deformity mandible revealed by three-dimensional functional unit analysis.

The 3D architecture of the mandible contributes to the functional and morphological characteristics of the lower one third of craniofacial region. The mandible has six distinct functional units, and its architecture is the sum of balanced growth of each functional unit and surrounding matrix. A dentofacial deformity (DFD) with malocclusion can be interpreted as their unbalanced growth. In order to characterize the mandibular 3D architecture, we analyzed the 3D reconstructed computed tomography (CT) images in terms of functional units. We evaluated both sides of 30 datasets of 3D CT scans of normal controls (N = 6) and patients with prognathic (N = 17) or retrognathic (N = 7) mandibles. We first identified and evaluated reference points to define mandibular functional units and compared their linear and angular measurements of DFD with normal group. The condylar and body length, the ratio of condyle/coronoid length, and the condylar head axis angle showed the statistically significant differences between groups. From these results, we could define the 3D reference points for functional units and identify the 3D architectural characteristics of DFD mandibles. These models may help us improve diagnosis and treatment planning to let them return to the normal and balanced architecture for DFD.

Modulation of cell proliferation during palatogenesis by the interplay between Tbx3 and Bmp4

During secondary palate development, two shelves are elevated to a horizontal position above the tongue through a process involving many cellular mechanisms, including proliferation. In particular, the expression patterns of Tbx3 and Bmp4, which are colocalized at embryonic day 13.5 (E13.5) and have unique expression patterns in specific regions at E14.5, have been investigated in early mouse palatogenesis. Tbx3 expression is reported to be associated with Bmp4 signaling during the process of organogenesis in other areas, such as limb development. However, the function of Tbx3 and the relationship between Tbx3 and Bmp4 in palate development have not been determined. We have examined the gene expression pattern and cell proliferation in order to understand the mutual interactions and function of Tbx3 and Bmp4. An electroporation method was used to investigate the altered pattern of these genes after their over-expression in organ cultures. NOGGIN protein-soaked beads were also implanted into the cultured palate to determine the function of Bmp4 in palatogenesis. After electroporation and NOGGIN bead implantation, the number of PCNA-positive cells was counted. The results showed that Tbx3 and Bmp4 strongly up- and down-regulated each other in order to control the proliferation of the palatal shelf. Thus, Tbx3 expression is induced by Bmp4 in the mesenchyme of the anterior palatal shelves, whereas mesenchymal expression of Tbx3 down-regulates Bmp4 expression in the mesenchyme of the palate. The harmonization between Tbx3 and Bmp4 therefore controls cell proliferation to regulate secondary palate development.

Reconstruction of the premaxilla by segmental distraction osteogenesis for maxillary retrusion in cleft lip and palate.

We present a strategy to target one of the main areas causing retruded maxilla, the premaxillary region for patients with cleft lip and palate (CLP). Advancement of the premaxilla by distraction osteogenesis is attempted, and the retruded anterior maxilla, the collapsed dental space, and the arch shape are sufficiently improved. This strategy also prevents deterioration of the velopharyngeal incompetency function. The procedure seems to be a good option for the treatment of maxillary retrusion and malocclusion for CLP.