Upper Airway Flow Dynamics in Obstructive Sleep Apnea Patients with Various Apnea-Hypopnea Index.

BACKGROUND AND AIM: This study evaluates the upper airway flow characteristics, anatomical features and analyzes their correlations with AHI in patients with varied degrees of OSA severity seeking for discernments of the underlying pathophysiological profile. MATERIALS AND METHODS: Patient-specific computational fluid dynamics models were reconstructed from high-resolution cone-beam computed tomography images for 4 OSA patients classified as minimal, mild, moderate, and severe according to AHI. RESULTS: The parameters, minimal cross-sectional area (MCA), and the pharyngeal airway volume did not show clear correlations with the OSA severity defined according to AHI. No correlations were found between the classically defined resistance of the airway in terms of pressure drop and AHI. The flow analysis further showed that the fluid mechanisms likely to cause airway collapse are associated with the degree of narrowing in the pharyngeal airway rather than AHI. Results also suggested that some patients classified as severe OSA according to the AHI can show less susceptibility to airway collapse than patients with relatively lower AHI values and vice versa. CONCLUSIONS: The relative contribution of anatomical and non-anatomical causes to the OSA severity can significantly vary between patients. AHI alone is inadequate to be used as a marker of the pathophysiological profile of OSA. Combining airflow analysis with AHI in diagnosing OSA severity may provide additional details about the underlying pathophysiology, subsequently improving the individualized clinical outcomes.

Continuous Positive Airway Pressure-Mandibular Advancement Device Combination Therapy for Moderate-to-Severe Obstructive Sleep Apnea: A Preliminary Study.

OBJECTIVES: The purpose of this pilot study was to determine whether compliance to auto-adjusting positive airway pressure (APAP) improves with the addition of a mandibular advancement device (MAD). Secondary outcome measures included were APAP pressure, subjective daytime sleepiness, apnea-hypopnea index (AHI), and mask leaks. SETTING AND SAMPLE POPULATION: Participants included were diagnosed with moderate-to-severe obstructive sleep apnea (OSA) and became noncompliant to prescribed APAP. Thirteen participants with a mean age of 61.6 years were recruited for this study. MATERIALS AND METHODS: All participants were given a MAD to use with their APAP. Parameters measured included APAP pressure, AHI, mask leak reported via ResMed AirViewTM software, and self-reported daytime sleepiness (Epworth Sleepiness Scale [ESS]). A paired two-sample for mean t-test was performed to determine significance. RESULTS: The mean difference of pre- and postintervention APAP compliance was 23.1%, which was statistically significant (p = 0.015). The mean APAP air pressures were unchanged. The difference between pre- and postintervention mean ESS scores was 1.4 and was statistically significant (p = 0.027). The mean difference between pre- and postintervention AHI values and mask leak showed no significant difference. CONCLUSION: This study showed that combination of APAP-MAD therapy, for patients with moderate-to-severe OSA who were noncompliant to APAP use, significantly increased compliance with APAP therapy, and significantly decreased the daytime sleepiness of participants.

Ethnic variation of oral microbiota in children.

Despite widely used preventive measures such as sealant programs to control caries prevalence, disparities are seen among ethnic groups. Supragingival plaque harbors hundreds of bacterial species, playing a significant role in oral health and disease. It is unknown whether the ethnic variation influences the supragingival microbiota in children. In our study, variations in microbiota of the supragingival plaque was investigated from 96 children between 6 and 11 years old in four ethnic groups (African American, Burmese, Caucasian, and Hispanic) from the same geographic location by 16S rRNA gene sequencing. We found that the microbial alpha and beta diversity of supragingival microbiota significantly differed between ethnic groups. The supragingival plaque microbiota had the most complex microbial community in Burmese children. Within-group microbiota similarity in Burmese or Caucasian children was significantly higher than between-groups similarity. We identified seven ethnic group-specific bacterial taxa after adjusting for dental plaque index, decayed missing filled teeth (DMFT) and the frequency of brushing. Children with high plaque index and high DMFT values were more similar to each other in the overall microbial community, compared to low plaque index or low DMFT groups in which inter-subject variation is high. Several bacterial taxa associated with high plaque index or high DMFT were ethnic group-specific. These results demonstrated that supragingival microbiota differed among ethnicity groups in children.

Surface nano-modification by ion beam-assisted deposition alters the expression of osteogenic genes in osteoblasts.

Biomaterials with enhanced biocompatibility are favored in implant studies to improve the outcomes of total joint replacement surgeries. This study tested the hypothesis that nano-structured surfaces for orthopedic applications, produced by the ion beam-assisted deposition method, would enhance osteointegration by altering the expression of bone-associated genes in osteoblasts. The ion beam-assisted deposition technique was employed to deposit nano-films on glass or titanium substrates. The effects of the ion beam-assisted deposition produced surfaces on the human osteosarcoma cell line SAOS-2 at the molecular level were investigated by assays of adhesion, proliferation, differentiation, and apoptosis on coated surfaces versus uncoated cobalt-chrome, as the control. Ion beam-assisted deposition nano-coatings enhanced bone-associated gene expression at initial cell adhesion, proliferation, and differentiation compared to cobalt-chrome surfaces as assessed by polymerase chain reaction techniques. Increased cell proliferation was observed using a nuclear cell proliferation-associated antigen. Moreover, enhanced cell differentiation was determined by alkaline phosphatase activity, an indicator of bone formation. In addition, programmed cell death assessed by annexin V staining and flow cytometry was lower on nano-surfaces compared to cobalt-chrome surfaces. Overall, the results indicate that nano-coated surfaces produced by the ion beam-assisted deposition technique for use on implants were superior to orthopedic grade cobalt-chrome in supporting bone cell adhesion, proliferation, and differentiation and reducing apoptosis. Thus, surface properties altered by the ion beam-assisted deposition technique should enhance bone formation and increase the biocompatibility of bone cell-associated surfaces.

An in-vitro evaluation of mechanical and esthetic properties of orthodontic sealants.

OBJECTIVE: To evaluate mechanical and esthetic Properties of two commercially available orthodontic sealants: Opal(®)Seal (OS) and L.E.D. Pro Seal (PS). MATERIALS AND METHODS: Discs of each sealant were prepared to test the following properties: Micro hardness, wear resistance and color stability. Samples were randomly selected after the wear test for SEM imaging to analyze surface morphology. RESULTS: OS was significantly harder than PS (P < 0.001). PS was significantly more wear resistant than OS (P < 0.05). PS showed a greater ∆E*ab (increased staining) when placed in wine or coffee showing a significant difference (P < 0.05). SEM showed particle size, shape and distribution were different for PS and OS reflecting the pattern seen on wear surfaces. CONCLUSION: Both orthodontic sealants are beneficial for protecting enamel. However with better wear properties PS was superior in resisting mechanical stresses. OS was more color stable.

Oral epithelial cell reaction after exposure to Invisalign plastic material.

INTRODUCTION: Invisalign plastic aligners (Align Technology, Santa Clara, Calif) are used to correct malocclusions. The aligners wrap around the teeth and are in contact with gingival epithelium during treatment. The purpose of this study was to evaluate the cellular responses of oral epithelium exposed to Invisalign plastic in vitro. METHODS: Oral epithelial cells were exposed to eluate obtained by soaking Invisalign plastic in either saline solution or artificial saliva for 2, 4, and 8 weeks. Cells grown in media containing saline solution or saliva served as controls. Morphologic changes were assessed by light microscopy. The 3-[4, 5-dimethythiazol- 2-yl]-2, 5-diphenyl tetrazolium bromide assay and flow cytometry were used to determine cell viability and membrane integrity, respectively. Cellular adhesion and micromotion of epithelial cells were measured in real time by electrical cell-substrate impedance sensing. RESULTS: Cells exposed to saline-solution eluate appeared rounded, were lifted from the culture plates, and demonstrated significantly increased metabolic inactivity or cell death (P <0.05). Saliva eluates did not induce significant changes in cell viability compared with untreated cells. Flow cytometry and electric cell-substrate impedance sensing showed that cells treated with saline-solution eluate exhibited compromised membrane integrity, and reduced cell-to-cell contact and mobility when compared with saliva-eluate treatment. CONCLUSIONS: Exposure to Invisalign plastic caused changes in viability, membrane permeability, and adhesion of epithelial cells in a saline-solution environment. Microleakage and hapten formation secondary to compromised epithelial integrity might lead to isocyanate allergy, which could be systemic or localized to gingiva. However, these results suggest that saliva might offer protection.

Focal adhesion kinase mediates ß-catenin signaling in periodontal ligament cells.

Periodontal ligament (PDL) cells convert the orthodontic forces into biological responses by secreting signaling molecules to induce modeling of alveolar bone and tooth movement. Beta-catenin pathway is activated in response to mechanical loading in PDL cells. The upstream signaling pathways activated by mechanical loading resulting in the activation of ß-catenin pathway through Wnt-independent mechanism remains to be characterized. We hypothesized that mechanical loading induces activation of ß-catenin signaling by mechanisms that dependent on focal adhesion kinase (FAK) and nitric oxide (NO). We found that mechanical or pharmacological activation of ß-catenin signaling in PDL cells upregulated the expression of ß-catenin target genes. Pre-treatment of PDL cells with FAK inhibitor-14 prior to mechanical loading abolished the mechanical loading-induced phosphorylation of Akt and dephosphorylation of ß-catenin. PDL cells pre-treated with NO donor or NO inhibitor and subjected to mechanical loading. Western blot analysis showed that the mechanical loading or pre-treatment with NO donor increased the levels of dephosphorylated ß-catenin, pAkt, and pGSK-3ß. Pre-treatment with NO inhibitor blocked the mechanical loading-induced phosphorylation of Akt and dephosphorylation of ß-catenin. These data indicate that mechanical loading-induced ß-catenin stabilization in PDL cells involves phosphorylation of Akt by two parallel pathways requiring FAK and NO.

Mechanical loading activates ß-catenin signaling in periodontal ligament cells.

OBJECTIVE: To determine whether ß-catenin signaling is responsive to mechanical loading in periodontal ligament (PDL) cells. MATERIALS AND METHODS: To determine whether Wnt/ß-catenin signaling pathway components are present and functional, PDL cells were treated with lithium chloride or Wnt3a-conditioned media. To determine whether mechanical strain activates ß-catenin signaling, PDL cells were subjected to compressive loading. Activation of the ß-catenin signaling pathway was determined by immunofluorescence, Western immunoblotting, and TOPflash assay. RESULTS: Mimicking Wnt signaling stimulates ß-catenin nuclear translocation and T-cell factor/lymphoid enhancer binding factor-dependent transcriptional activation in PDL cells. Mechanical loading stimulates a transient accumulation of dephosphorylated ß-catenin in the cytoplasm and its translocation to the nucleus. This effect of strain acts through activation of protein kinase B and phosphorylation of glycogen synthase kinase-3 beta. These strain-related changes do not involve the low-density lipoprotein receptor-related protein 5/Wnt receptor. CONCLUSIONS: The Wnt/ß-catenin signaling pathway components are functional and activated by mechanical loading in PDL cells. ß-catenin serves as an effector of mechanical signals in PDL cells.