Delayed Soft Tissue Changes after Clockwise Rotation of the Maxillo-Mandibular Complex.

OBJECTIVE: The purpose of this study was to evaluate delayed soft tissue changes of the maxilla-mandibular complex MMC using three-dimensional (3D) cone-beam computed tomography after clockwise repositioning orthognathic surgery. METHODS: This study included 21 patients that underwent maxilla-mandibular complex clockwise rotational orthognathic surgery by 1 doctor from January 2015 to June 2019. Radiographic images (panorama, lateral cephalogram, posteroanterior view, and conebeam computed tomography) were taken and 3D analysis was performed using the Invivo 5 (Anatomage Inc, Santa Clara, CA) to acquire 3D images before surgery, immediately after surgery, at 6 months after surgery and 21 months after surgery. The 9 soft tissue landmarks were measured and compared in terms of postoperative changes in transverse, vertical, and anteroposterior directions. The points were at the outer commissure of the eye fissure (Exocathion; Exc_r, Exc_l), at the midline of both the nasal root and the nasofrontal suture, analogous to bony N (soft tissue nasion; N), the most prominent point on the nasal tip (Pronasale; Prn), the most lateral point in the curved baseline of each ala, indicating the facial insertion of the nasal wing base (Alare curvature; Ac_r, Ac_l), the most lateral point on the soft tissue contour of each mandibular angle (Soft tissue Gonion; Go_r, Go_l), and the most inferior midpoint on the soft tissue contour of the chin (soft tissue menton; Me). RESULTS: The most prominent point of the nasal tip (Prn) moved 1.36 mm upward and 1.55 mm forward in the vertical and anteroposterior planes immediately after surgery. However, there were no significant changes in Ac_r and Ac_l even immediately after surgery. Both soft tissue gonions shifted downward and forward between immediately after surgery and 6 months after surgery. However, no significant change was observed in the value of any of the 9 soft tissue points between 6 months and 21 months after surgery ( P value < 0.05). CONCLUSIONS: No significant changes were observed between 6 and 21 months after surgery, which suggests no delayed soft tissue changes occur in surgically treated patients after the resolution of surgically-related facial edema and swelling and postsurgical remodeling of hard tissue in overlying soft tissue.

Effects of photobiomodulation on bone remodeling in an osteoblast-osteoclast co-culture system.

The general bone anabolic effect of photobiomodulation (PBM) is largely accepted. As a result, PBM therapy is expected to be beneficial in the medical fields of dentistry and bone healing. However, most of the previous in vitro studies on PBM and bone metabolism were performed with single-cell cultures of osteoclast-lineage cells or osteoblast-lineage cells. In the present study, the bone-modulating effects of PBM were evaluated in an in vitro osteoblast/osteoclast co-culture system. Mouse bone marrow-derived macrophages (BMMs) and mouse calvarial pre-osteoblasts cells were purified and used as precursor cells for osteoclasts and osteoblasts, respectively. The PBM effects on single-cell culture of osteoclasts or osteoblasts as well as co-culture were examined by 1.2 J/cm2 low-level Ga-Al-As laser (λ = 808 ± 3 nm, 80 mW, and 80 mA; spot size, 1cm2; NDLux, Seoul, Korea) irradiation for 30 s at daily intervals throughout culture period. At the end of culture, the osteoclast differentiation and osteoblast differentiation were assessed by TRAP staining and ALP staining, respectively. The expressions of osteoclastogenic cytokines were evaluated by RT-PCR and Western blot analyses. Under the single-cell culture condition, PBM enhanced osteoblast differentiation but had minor effects on osteoclast differentiation. However, in the co-culture condition, its osteoblastogenic effect was maintained, and osteoclast differentiation was substantially reduced. Subsequent RT-PCR analyses and western blot results revealed marked reduction in receptor activator of NF-κB ligand (RANKL) expression and elevation in osteoprotegerin (OPG) expression by PBM in co-cultured cells. More importantly, these alterations in RANKL/OPG levels were not observed under the single-cell culture conditions. Our results highlight the different effects of PBM on bone cells based on culture conditions. Further, our findings suggest the indirect anti-osteoclastogenic effect of PBM, which is accompanied by a decrease in RANKL expression and an increase in OPG expression.

Automatic three-dimensional analysis of bone volume and quality change after maxillary sinus augmentation.

INTRODUCTION: Maxillary sinus augmentation is a widely used surgical procedure to increase the bone volume before implant placement. In order to predict the stability of the implant, analysis of the change in bone volume and quality after a sinus graft procedure is necessary. The purpose of this study was to analyze the change in volume and quality of bone graft material after maxillary sinus augmentation using cone beam computed tomography (CBCT). METHODS AND MATERIALS: Maxillary sinus lift procedures using bovine bone materials (Bio-Oss, Geistrich, Swiss) without immediate implantation were performed at the Pusan National University Dental Hospital in 22 patients, from 2014 to 2017. CBCT images were captured before surgery (T1), a day after surgery (T2), and after 4 to 7 months at follow-up (T3). The T2 and T3 images were registered to the T1 image using histogram matching and intensity-based registration. A total of 30 sinuses were analyzed three-dimensionally (3-D), using self-made software MATLAB 2018a (MathWorks, Natick, Massachusetts). The volume and structural indices of the bone graft material were measured and analyzed. RESULTS: The average volume of graft material showed a decrease, while the average gray value showed an increase during the follow-up period, but these changes were not statistically significant. The structural indices of the graft material after histogram matching showed a significant difference in homogeneity, connectivity, thickness, and roughness at the postoperative follow-up. CONCLUSIONS: The volume and gray value showed no statistically significant changes after the maxillary sinus lift procedures. The results of this study show that structural analysis using histogram matching can be used as a promising tool to analyze the quality of graft materials.