Effects of the Mandibular Functional Units and Soft Tissue on Facial Asymmetry.

Mandibular asymmetry has a variety of patterns because they are affected the position and the shape of mandible in addition to the overlying soft tissue. This study aimed to assess the factor in mandibular asymmetry, focusing on each mandibular functional units and the soft tissue thickness in the mandibular angle area. Forty patients who were diagnosed with facial asymmetry and undergone the orthognathic surgery without genioplasty were enrolled in this study. The skeletal patterns of the patients were analyzed by using cone-beam computed tomography data and 3D virtual images divided into 2 categories; the mandibular functional unit length and the soft tissue depth. All difference in bilateral mandibular functional unit lengths had a statistically significant with chin top deviation ( P <0.05). The greatest correlation was the condylar unit length compared with other functional units. The soft tissue thickness in the mandibular angle area was not statistically related to chin top deviation ( P >0.05), and the soft tissue did not change remarkably after orthognathic surgery ( P >0.05). This study suggests that the considerations of a surgical plan for treatment based on the mandibular asymmetry.

Which Skeletal Factors Can Affect Lip Canting in Facial Asymmetry?: Statistical Analysis.

Lip canting, which is a noticeable factor in patients with facial asymmetry, can be influenced by the dentofacial skeleton. During orthognathic surgery, postoperative changes in facial soft tissue occur along the newly positioned hard tissue. Therefore, the evaluation of soft tissue before surgery is important. The purpose of this study was to investigate the skeletal factors that can affect lip canting by statistically comparing 2 facial horizontal planes using a three-dimensional reconstruction model. The findings of the present study showed a statistical correlation between lip canting and 3 skeletal factors: menton deviation, maxillary canting, and ramal length differences. Furthermore, a statistical correlation was identified between the Frankfort Horizontal plane and the intercanthal plane compared with the lip canting line. This result suggests that the intercanthal plane could be a standard horizontal plane in three-dimensional reconstruction model analysis.

Zygoma Augmentation With 3D Printed Bioactive Glass-Ceramic Implant.

ABSTRACT: Zygoma, which is located at the middle third of the face, has a significant impact on the facial impression with its volume and prominence. CaO-SiO 2 -P 2 O 5 -B 2 O 3 glass-ceramics (BGS-7) has been reported as a new alternative of nonresorbable bone grafting material, which has bioactivity of inducing human osteoblast between bone and implant, resulting integration to the bone. Furthermore, its chemical characteristics are similar to bone, resulting in radiopacity with no metallic artifact on the radiographic images. With the development of Computer aided design-Computer aided manufacturing technology, BGS-7 can be manufactured into a patient-specific design.During follow-up periods, 3D printed BGS-7 implant did not displace from the initial recipient site. By cone-beam computed tomography evaluation, a gap between bone and BGS-7 was filled with the radiopacity, which implied bony fusion. Consequently, this clinical case shows that the BGS-7 implant could be an effective and safe graft material for zygoma bone defects.

A clinical retrospective study of implant as a risk factor for medication-related osteonecrosis of the jaw: surgery vs loading?

BACKGROUND: Risk factors for developing medication-related osteonecrosis of the jaw (MRONJ) include the general condition of the patient, smoking habit, poor oral hygiene, and the type, duration, and administration route of the drug, dentoalveolar surgery, such as implant placement. This study aimed to discuss whether implants may induce osteonecrosis in older patients receiving long-term medication and to analyze the radiological pattern of the bone necrosis. METHODS: This study included 33 patients diagnosed with dental implant-associated medication-related osteonecrosis of the jaw. Data regarding the medical history, type of medication used, durations of administration, laboratory test results, onset of bone necrosis since implant placement, type of opposing teeth, and radiological pattern of the bone necrosis on cone-beam computed tomography were recorded in patients with and without implants. RESULTS: The most commonly used drug was bisphosphonate, with an average duration of use of 61.37 (± 53.72) months. The laboratory results showed average serum C-terminal cross-linking telopeptide (CTX) level of 0.23 ng/mL, vitamin D, 23.42 ng/mL, and osteocalcin, 4.92 ng/mL. Osteonecrosis occurred after an average of 51.03 (± 39.75) months following implant placement. Radiological evaluation revealed obvious sequestration in the implant-absent group, and the formation of a unit sequestration with an implant fixture (en bloc) was observed in the implant-present group. The patients underwent surgical treatment of sequestrectomy and explantation. CONCLUSION: Implant placement, especially loading, may be considered a potential risk factor for the development of osteonecrosis in patients undergoing antiresorptive treatment.

Posterior bending osteotomy: An effective measure to secure facial symmetry in orthognathic surgery.

This study aimed to compare the effectiveness of posterior bending osteotomy and grinding techniques for orthognathic surgery in patients with facial asymmetry. Patients who had undergone Le Fort I osteotomy and bilateral sagittal split ramus osteotomy, and who presented with a menton shift and setback difference exceeding 4 mm, were enrolled. Cone-beam computed tomography was performed before surgery (T0), immediately after surgery (T1), and 6 months after surgery (T2). Overall, 38 patients were included and divided into posterior bending osteotomy (n = 23) and grinding (n = 15) groups. Significant differences were observed between the posterior bending osteotomy and grinding groups on the treated side. In the grinding group, the gonion on the treated side was displaced slightly outward, resulting in a significant difference between both sides (non-treated side: 50.52 ± 4.20 [T0] and 48.67 ± 4.37 [T2]; treated side: 50.88 ± 4.55 [T0] and 51.00 ± 3.95 [T2]; p = 0.038). In the posterior bending osteotomy group, bilateral inward movements of the gonion were observed, and the distance from the midsagittal plane to the gonion did not differ significantly between the sides (non-treated side: 46.74 ± 4.41 [T0] and 45.54 ± 3.95 [T2]; treated side: 47.43 ± 4.93 [T0] and 45.18 ± 3.52 [T2]; p = 0.224). The yawing movement of the proximal segment was greater in the grinding group than in the posterior bending osteotomy group (non-treated side: p = 0.839; treated side: p = 0.025). Posterior bending osteotomy is recommended over the grinding method for patients with severe facial asymmetry, in order to ensure a symmetric and esthetic facial profile by allowing passive adaptation between the mandibular segments.