A Polysaccharide-Based Antibacterial Coating with Improved Durability for Clear Overlay Appliances.

Clear overlay appliances (COAs) are widely used in orthodontic fields because they offer many advantages, such as cost-effectiveness, good formability, and good optical characteristics. However, it is necessary to frequently replace COAs because the thermoplastic polymers that are used to fabricate COAs have poor abrasion resistance and have a tendency to induce bacterial accumulation. Here, we have developed polysaccharide-based antibacterial multilayer films with enhanced durability, intended for COA applications. First, multilayer films composed of carboxymethylcellulose (CMC) and chitosan (CHI) were fabricated on polyethylene terephthalate glycol-modified (PETG), which was preferred material for COA fabrication, via a layer-by-layer (LbL) technique. Next, chemical cross-linking was introduced within the LbL-assembled multilayer films. The LbL-assembled CMC/CHI film, which was made porous and rough by the cross-linking, formed a superhydrophilic surface to prevent the adhesion of bacteria and exhibited a bacterial reduction ratio of ∼75%. Furthermore, the cross-linking of the multilayer film coated on the PETG also improved the chemical resistance and mechanical stability of the PETG under simulated intraoral conditions with artificial saliva, by increasing the bond strength between the polysaccharide chains. We attempted to accumulate datasets using our experimental design and to develop sophisticated methods to assess nanoscale changes through large-scale measurements.

Sequential changes of postoperative condylar position in patients with facial asymmetry.

OBJECTIVE: To evaluate sequential images of the condylar position in relation to the glenoid fossa after orthognathic surgery in patients with facial asymmetry using cone beam computed tomography. MATERIALS AND METHODS: A total of 20 adult patients (11 men and 9 women; mean age, 22.1 ± 4.02 years) with facial asymmetry who underwent sagittal split ramus osteotomy with rigid fixation were involved. Cone beam computed tomography scans were obtained before treatment (T0), 1 month before the surgery (T1), and 1 day (T2), 3 months (T3), 6 months (T4), and 12 months (T5) after the surgery. The condyle position was evaluated. RESULTS: At 1 day after surgery (T2), the condylar position on both sides significantly changed posteriorly, inferiorly, and laterally, but no significant difference was observed between the nonaffected and affected sides. The condyle on the nonaffected side had a tendency to recover its preoperative position at 3 months after surgery (T3) and inclined slightly laterally up to 1 year after the surgery (T5). The condyle on the affected side returned more closely to the glenoid fossa than to its pretreatment position at 3 months after surgery (T3). Thereafter, it showed a more backward and downward position (T5). CONCLUSIONS: The overall condylar position after an orthognathic surgery in patients with facial asymmetry was relatively stable at 1 year after surgery. However, the condyle on the affected side during the first 3 months after surgery should be carefully monitored for surgical stability.

Anterior Decompensation Using Segmental Osteotomy for Patients With Mandibular Asymmetry.

To obtain sufficient correction of facial asymmetry by orthognathic surgery, precise and sufficient dental decompensation during preoperative orthodontic treatment is needed. Facial asymmetry often includes complicated 3-dimensional dental compensation in the anterior alveolar region, which can limit the treatment options and lengthen the treatment time. As an alternative, anterior decompensation using segmental osteotomy (ADSO) with the patient under local anesthesia could be a reasonable approach, as it represents an effective, selective, and relatively safe method for correcting lower anterior disharmony during preoperative treatment. Furthermore, ADSO can quickly eliminate anterior compensation and move the teeth to their proper positions such that the basal bone supports them beyond the anatomic limits. Precise evaluation and diagnosis using data obtained from 3-dimensional computed tomography should be performed for accurate ADSO. The present report describes the versatile use of ADSO for 2 patients with different types of severe facial asymmetry. In the first case, ADSO was performed to correct the anterior dentoalveolar yaw and in the second, to change the vertical positioning and inclination of the anterior teeth. In both cases, sufficient elimination of anterior compensation using ADSO guaranteed successful improvement of the facial asymmetry and stabilization of occlusion after orthognathic surgery. The use of ADSO during preoperative treatment can quickly and effectively correct lower anterior disharmony and facilitate surgical correction of facial asymmetry.