The changes in oral volume and hyoid bone position after maxillomandibular advancement and genioglossus advancement for patients with obstructive sleep apnea.

INTRODUCTION: Maxillomandibular advancement (MMA) and genioglossus advancement (GA) are surgeries for patients with obstructive sleep apnea (OSA). Postoperative evaluation is primarily based on the apnea-hypopnea index (AHI) measured by polysomnography. The purpose of this study was to identify the timing of hyoid bone relocation after MMA and GA surgery and to investigate whether or not hyoid bone relocation can be an indicator of postoperative evaluation of OSA. METHODS: Patients with OSA underwent MMA and GA surgery. Changes in hyoid bone position and tongue-to-oral volume ratio were analyzed on lateral radiographs before, immediately after, and 1 year after surgery. Then, a correlation was verified between these changes and postoperative AHI. RESULTS: In 18 patients studied, the position of the hyoid bone did not show a constant tendency immediately after surgery. One year after surgery, the bone had moved anteriorly and toward the oral cavity in all patients compared to its preoperative position. And AHI correlated with the movement of the hyoid bone to the oral side. DISCUSSION: One year after surgery, the tongue was adapted to the newly enlarged oral space, and as a result, the low position of the hyoid bone before the operation was improved. The findings suggest that the degree of lowering of the hyoid bone may be an indicator of the improvement of AHI.

Histone-deacetylase-inhibitory effects of periodontopathic-bacterial metabolites induce human gingival epithelial Ca9-22 cell death.

Dental plaque bacteria produce high concentrations of short-chain fatty acids (SCFAs), as bacterial metabolites. SCFA-treated gingival epithelial cells undergo cell death. Our previous reports demonstrated that butyrate-induced cell death depends on autophagy and reactive oxygen species (ROS). However, the precise mechanisms underlying SCFA-induced gingival epithelial cell death is poorly understood. Butyrate is a strong histone deacetylase (HDAC) inhibitor. Therefore, we determined the involvement of HDAC inhibitory activity in SCFA-induced gingival epithelial cells. Ca9-22 cells were used as an in vitro counterpart of gingival epithelial cells. Ca9-22 cells were treated with HDAC inhibitors in the presence or absence of C646, a P300 histone acetyltransferase (HAT) inhibitor, and compared the number of dead cells, which are measured using SYTOX Green dye. Acetylation levels of histone H3 were examined using western blotting. Changes in transcriptomes during the butyrate and C646 treatment were examined using RNA sequencing analysis. The butyrate or propionate-treatment of Ca9-22 cells induced acetylation of histone H3, while the C646 treatment strongly reduced the elevated acetylation levels. Accordingly, butyrate or propionate-induced cell death was inhibited by the C646 treatment. Similar results were obtained when other HDAC inhibitors were used. Whole transcriptome analysis revealed that the expression of numerous genes was altered by butyrate-induced histone acetylation. Moreover, some autophagy and ROS-related genes found in the altered genes might induce cell death. This study suggests the need for HDAC-inhibitory activity of bacterial metabolites to induce cell death, and the effects might enhance autophagy and ROS production.

Reactive oxygen species generation required for autophagy induction during butyrate- or propionate-induced release of damage-associated molecular patterns from dying gingival epithelial Ca9-22 cells.

PURPOSE: Bacterial cells in mature dental plaque produce a high concentration of short-chain fatty acids (SCFAs) such as butyrate and propionate. SCFA-treatment on human gingival epithelial Ca9-22 cells induced cell death. However, the exact mechanism underlying cell death remains unclear. In this study, the relationship between reactive oxygen species (ROS) and autophagy induction during SCFA-induced cell death was examined. METHODS: Human gingival epithelial Ca9-22 cells were treated with butyrate or propionate to induce cell death and the number of dead cells were measured using SYTOX-green dye. A siRNA for ATG5 and N-acetylcysteine (NAC) were used for autophagy reduction and ROS-scavenging, respectively. Release of damage-associated molecular patterns (DAMPs) such as Sin3A-associated protein 130 (SAP130) and high-mobility group box 1 (HMGB1) were detected using western blot. RESULTS: Reducing autophagy significantly suppressed SCFA-induced Ca9-22 cell death. ROS generation was observed upon SCFA treatment, and scavenging ROS with NAC decreased cell death. NAC also reduced the SCFA-induced increase in microtubule-associated protein 1 light chain 3B (LC3B)-I and LC3B-II, and mitigated the release of DAMPs. CONCLUSION: The findings suggest that ROS generation is necessary for autophagy, which is required for SCFA-induced cell death and accompanying DAMP release.

Butyrate-treatment induces gingival epithelial cell death in a three-dimensional gingival-connective tissue hybrid co-culture system.

Three-dimensional (3D) cell culture systems are reported to be more physiologically similar to the in vivo state than 2-dimensional (2D) models, which are extensively employed in periodontal research. Herein, we developed a 3D gingival tissue model with both epithelial and lamina propria layers using human gingival epithelial Ca9-22 cells and primary gingival fibroblasts. The epithelial layer of the developed 3D gingival tissue culture was treated with butyrate, a metabolite of oral bacteria, and the treatment induced the release of damage-associated molecular patterns, such as DNA and Sin3A associated protein 130 kDa (SAP130). Taken together, butyrate exposure to the epithelium of 3D gingival epithelial-connective tissue hybrid systems could induce epithelial cell death and the subsequent release of damage-associated molecular patterns.

New method of Le Fort I osteotomy with increased stability.

Backsliding is a major problem when moving the maxilla significantly forward in orthognathic surgery. For example, in sleep surgery, maxillomandibular advancement is an application of orthognathic surgery, and it is well known that the anterior movement of the maxilla back and forth is an important factor that greatly widens the pharyngeal airway. However, postoperative backsliding is a major problem in this surgery. Therefore, a surgical method was devised to prevent the maxilla from retracting by adjusting the bone when moving the maxilla forward.

A preoperative predictive study of advantages of airway changes after maxillomandibular advancement surgery using computational fluid dynamics analysis.

The purpose of this study was to develop a simulation approach for predicting maxillomandibular advancement-induced airway changes using computational fluid dynamics. Eight patients with jaw deformities who underwent maxillomandibular advancement and genioglossus advancement surgery were included in this study. Computed tomography scans and rhinomanometric readings were performed both preoperatively and postoperatively. Computational fluid dynamics models were created, and airflow simulations were performed using computational fluid dynamics software; the preferable number of computational mesh points was at least 10 million cells. The results for the right and left nares, including simulation and postoperative measurements, were qualitatively consistent, and surgery reduced airflow pressure loss. Geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. Simulations were performed with either the right or left naris blocked, and the predicted values were similar to those found clinically. In addition, geometry prediction simulation results were qualitatively consistent with the postoperative stereolithography data and postoperative simulation results. These findings suggest that geometry prediction simulation facilitates the preoperative prediction of the postoperative structural outcome.

Cephalometric analysis of the pharyngeal airway space after maxillary advancement surgery.

This study evaluated the effect of maxillary advancement surgery on the size of the pharyngeal airway space (PAS). Lateral cephalometric radiographs were collected for 90 patients (29 men and 61 women; average age, 27.2 ± 8.1 years) before (T1) and 1 year after (T2) maxillary advancement surgery. Horizontal and vertical changes in the maxilla and PAS were measured and classified by distance. The maxilla was advanced horizontally by 2.9 ± 1.7 mm and vertically by 2.7 ± 1.4 mm. Upward maxillary movement of ≥4 mm significantly increased PAS (mean change in PAS, 2.6 mm), and upward maxillary movement significantly decreased the posterior nasal spine to the P-point. Only patients with vertical advancement ≥4 mm and horizontal advancement of 3 mm had significant increases in all three PAS parameters. Although forward maxillary movement is believed to have a large effect on PAS, it is suggest that upward vertical movement is more effective for improving PAS. Both the extent and direction of maxillar movement should be considered. Future studies should use cone-beam computed tomography to evaluate the effect of axial direction and differences in PAS.

Computational fluid dynamics analysis for the preoperative prediction of airway changes after maxillomandibular advancement surgery.

Maxillomandibular advancement surgery is useful for treatment of sleep apnea. However, preoperative analysis and evaluation to facilitate decision-making regarding the direction and distance of maxillomandibular movement has primarily consisted of morphological analysis; physiological function is not evaluated. To improve preoperative prediction, this study used fluid simulation to investigate the characteristics and effects of airway changes associated with maxillomandibular movement. A one-dimensional model with general applicability was thus developed. Actual measurements of flow in patients were used in this fluid simulation, thus achieving an analysis closer to clinical conditions. The simulation results were qualitatively consistent with the actual measurements, which confirmed the usefulness of the simulation. In addition, the results of the one-dimensional model were within the error ranges of the actual measurements. The present results establish a foundation for using accumulating preoperative measurement data for more-precise prediction of postoperative outcomes.

Rapid detection of Candida albicans in oral exfoliative cytology samples by loop-mediated isothermal amplification.

Loop-mediated isothermal amplification (LAMP) rapidly amplifies DNA under isothermal conditions. The aim of this study was to detect Candida albicans and compare the positivity rate in the LAMP reaction with that of conventional methods for oral exfoliative cytology (EC) samples. Sixty-eight EC samples from 53 patients were subjected to LAMP analysis. These patients had been clinically diagnosed with leukoplakia, squamous cell carcinoma, oral lichen planus (OLP), stomatitis, oral candidiasis, and other malignancies. LAMP reactions were defined as positive when the sample turbidity exceeded 0.1 (arbitrary unit). Periodic acid-Schiff (PAS) staining and microbial culture were also performed to detect Candida species in EC samples. The LAMP reaction detected C. albicans in 42.6% of EC samples. Candida species were detected in 32.4% of the same samples by culturing and in 29.4% of samples by PAS staining. C. albicans DNA was detected most frequently in samples from OLP patients. We conclude that, in comparison to conventional methods for detection of C. albicans, the LAMP method is highly sensitive and time-saving, and does not require expensive equipment or diagnostic technology. It may therefore be useful for on-site screening of C. albicans at dental clinics.