A Review of Biodegradable Plastics: Chemistry, Applications, Properties, and Future Research Needs.

Environmental concerns over waste plastics' effect on the environment are leading to the creation of biodegradable plastics. Biodegradable plastics may serve as a promising approach to manage the issue of environmental accumulation of plastic waste in the ocean and soil. Biodegradable plastics are the type of polymers that can be degraded by microorganisms into small molecules (e.g., H2O, CO2, and CH4). However, there are misconceptions surrounding biodegradable plastics. For example, the term "biodegradable" on product labeling can be misconstrued by the public to imply that the product will degrade under any environmental conditions. Such misleading information leads to consumer encouragement of excessive consumption of certain goods and increased littering of products labeled as "biodegradable". This review not only provides a comprehensive overview of the state-of-the-art biodegradable plastics but also clarifies the definitions and various terms associated with biodegradable plastics, including oxo-degradable plastics, enzyme-mediated plastics, and biodegradation agents. Analytical techniques and standard test methods to evaluate the biodegradability of polymeric materials in alignment with international standards are summarized. The review summarizes the properties and industrial applications of previously developed biodegradable plastics and then discusses how biomass-derived monomers can create new types of biodegradable polymers by utilizing their unique chemical properties from oxygen-containing functional groups. The terminology and methodologies covered in the paper provide a perspective on directions for the design of new biodegradable polymers that possess not only advanced performance for practical applications but also environmental benefits.

Development of Houttuynia cordata Extract-Loaded Solid Lipid Nanoparticles for Oral Delivery: High Drug Loading Efficiency and Controlled Release.

Houttuynia cordata (H. cordata) has been used for diuresis and detoxification in folk medicine as well as a herbal medicine with antiviral and antibacterial activities. H. cordata extract-loaded solid lipid nanoparticles (H-SLNs) were prepared with various concentration of poloxamer 188 or poloxamer 407 by a hot homogenization and ultrasonication method. H-SLNs dispersion was freeze-dried with or without trehalose as a cryoprotectant. The physicochemical characteristics of H-SLNs were evaluated by dynamic laser scattering (DLS), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). Additionally, the in vitro release and in vitro cytotoxicity of H-SLNs were measured. Encapsulation efficiencies of H-SLNs (as quercitrin) were 92.9-95.9%. The SEM images of H-SLNs showed that H-SLNs have a spherical morphology. DSC and FT-IR showed that there were no interactions between ingredients. The increased extent of particle size of freeze-dried H-SLNs with trehalose was significantly lower than that of H-SLNs without trehalose. H-SLNs provided sustained release of quercitrin from H. cordata extracts. Cell viability of Caco-2 cells was over 70% according to the concentration of various formulation. Therefore, it was suggested that SLNs could be good carrier for administering H. cordata extracts.

Preparation of High-Payload, Prolonged-Release Biodegradable Poly(lactic-co-glycolic acid)-Based Tacrolimus Microspheres Using the Single-Jet Electrospray Method.

Tacrolimus-loaded poly(lactic-co-glycolic acid) microspheres (TAC-PLGA-M) can be administered for the long-term survival of transplanted organs due to their immunosuppressive activity. The purpose of our study was to optimize the parameters of the electrospray method, and to prepare TAC-PLGA-M with a high payload and desirable release properties. TAC-PLGA-M were prepared using the electrospray method. In vitro characterization and evaluation were performed using scanning electron microscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier-transform infrared spectroscopy. Drug-loading efficiency was greater than 80% in all formulations with a maximum loading capacity of 16.81±0.37%. XRD and DSC studies suggested that the drug was incorporated in an amorphous state or was molecularly dispersed in the microspheres. The in vitro release study showed prolonged release patterns. TAC-PLGA-M with enhanced drug loading and prolonged-release patterns were successfully prepared using the electrospray method.

Pre-clinical evaluation of the osteogenic potential of bone morphogenetic protein-2 loaded onto a particulate porcine bone biomaterial.

AIM: The objective of study was to determine the osteogenic potential of bone morphogenetic protein-2 (BMP-2) loaded onto a particulate porcine bone mineral (PBM) biomaterial using a sinus augmentation model. METHODS: Release kinetics of BMP-2/PBM was determined in vitro. Eight rabbits received BMP-2/PBM or PBM alone into contra-lateral sinus sites. The animals were killed following a 2-week healing interval for micro-CT and histometrical analysis. RESULTS: Approximately 40% of the BMP-2 was released from PBM over the first 3 days in vitro; release maintained at a reduced level through day 21. In vivo, total augmented implant volume did not differ significantly between treatments. However, local bone formation was enhanced in the BMP-2/PBM group compared with PBM control (10.5% versus 6.6%; p = 0.03), specifically in the central aspect of the PBM implant (14.2% versus 5.5%; p < 0.01) and adjoining the Schneiderian membrane (11.9% versus 5.0%; p < 0.05). There were no significant overall differences in residual biomaterial and fibrovascular tissue. CONCLUSION: Bone morphogenetic protein-2 enhanced local bone formation in the rabbit maxillary sinus model following implantation using a PBM carrier.

Prospective randomized, controlled trial of sinus grafting using Escherichia-coli-produced rhBMP-2 with a biphasic calcium phosphate carrier compared to deproteinized bovine bone.

AIM: This study compared the effects of Escherichia-coli-produced recombinant human bone morphogenetic protein 2 (ErhBMP-2) with a biphasic calcium phosphate (BCP) carrier to those of deproteinized bovine bone in human maxillary sinus floor augmentation. MATERIAL AND METHODS: Screening for this clinical trial selected 56 sites that provided informed consent to participate, of which 46 were ultimately enrolled and 41 were finally included in the study. The sites were divided into two groups using a random-number table, and the material was applied. A trephine biopsy was performed after 24 weeks, and implants wider than the biopsy site were inserted. Computed tomography and plain panoramic images were obtained immediately and then again at 24 weeks after the surgery. Radiographic images were reconstructed to allow measurement of the linear and volumetric changes. The biopsy samples were processed for histologic and histometric analyzes. RESULTS: All sites healed uneventfully with no complications. Radiographic analysis revealed a tendency for the volume to increase, but the difference was not statistically significant in either group. Comparison of volumetric changes between the two groups also revealed no significant difference. Moreover, none of the histometric parameters differed significantly between the groups, although different healing patterns were observed on histologic analysis. CONCLUSIONS AND CLINICAL IMPLICATIONS: It can be concluded that sinus augmentation with ErhBMP-2 carrying BCP carrier did not enhance bone regeneration compared to the conventional treatment using deproteinized bovine bone at 24 weeks after the surgery.

Comparison of collagen membrane and bone substitute as a carrier for rhBMP-2 in lateral onlay graft.

OBJECTIVES: To evaluate the bone regenerative effect of bioresorbable collagen membrane (CM) as a carrier for recombinant human bone morphogenetic protein-2 (rhBMP-2) when performing lateral onlay grafts using bovine hydroxyapatite incorporated with collagen matrix (BHC) in combination with CM in dogs. MATERIAL AND METHODS: A guided bone regeneration (GBR) was performed at the buccal aspect of edentulous maxillary alveolar ridges in dogs (n = 5): (1) BHC group, in which rhBMP-2-loaded BHC was covered by a CM, and (2) CM group, in which BHC was covered by an rhBMP-2-loaded CM. A histologic and histometric analysis was performed after 8 weeks of healing. RESULTS: Both the BHC and CM groups exhibited substantial newly formed bone (NB). More NB was found in the CM group than in the BHC group without statistical significance. Most of the NB was in direct contact with the residual bone substitute in the BHC group, whereas the projections and islands of NB were observed in the spaces between the residual bone substitute clusters in the CM group. The bone-to-residual bone substitute contact ratio was significantly lower in the CM group than in the BHC group (P = 0.043). CONCLUSIONS: Within the limitations of this study, it can be concluded that rhBMP-2-loaded CM performed lateral onlay grafts as effectively as rhBMP-2-loaded BHC while showing less bone-residual bone substitute contact ratio in dogs. The loading of CMs with rhBMP-2 might therefore be a recommendable treatment option for facilitating lateral onlay graft combined with rhBMP-2.

Preparation and in vivo evaluation of a dutasteride-loaded solid-supersaturatable self-microemulsifying drug delivery system.

The purpose of this study was to prepare a dutasteride-loaded solid-supersaturatable self-microemulsifying drug delivery system (SMEDDS) using hydrophilic additives with high oral bioavailability, and to determine if there was a correlation between the in vitro dissolution data and the in vivo pharmacokinetic parameters of this delivery system in rats. A dutasteride-loaded solid-supersaturatable SMEDDS was generated by adsorption of liquid SMEDDS onto Aerosil 200 colloidal silica using a spray drying process. The dissolution and oral absorption of dutasteride from solid SMEDDS significantly increased after the addition of hydroxypropylmethyl cellulose (HPMC) or Soluplus. Solid SMEDDS/Aerosil 200/Soluplus microparticles had higher oral bioavailability with 6.8- and 5.0-fold higher peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) values, respectively, than that of the equivalent physical mixture. A linear correlation between in vitro dissolution efficiency and in vivo pharmacokinetic parameters was demonstrated for both AUC and Cmax values. Therefore, the preparation of a solid-supersaturatable SMEDDS with HPMC or Soluplus could be a promising formulation strategy to develop novel solid dosage forms of dutasteride.

Enhanced supersaturation and oral absorption of sirolimus using an amorphous solid dispersion based on Eudragit® e.

The present study aimed to investigate the effect of Eudragit® E/HCl (E-SD) on the degradation of sirolimus in simulated gastric fluid (pH 1.2) and to develop a new oral formulation of sirolimus using E-SD solid dispersions to enhance oral bioavailability. Sirolimus-loaded solid dispersions were fabricated by a spray drying process. A kinetic solubility test demonstrated that the sirolimus/E-SD/TPGS (1/8/1) solid dispersion had a maximum solubility of 196.7 µg/mL within 0.5 h that gradually decreased to 173.4 µg/mL after 12 h. According to the dissolution study, the most suitable formulation was the sirolimus/E-SD/TPGS (1/8/1) solid dispersion in simulated gastric fluid (pH 1.2), owing to enhanced stability and degree of supersaturation of E-SD and TPGS. Furthermore, pharmacokinetic studies in rats indicated that compared to the physical mixture and sirolimus/HPMC/TPGS (1/8/1) solid dispersion, the sirolimus/E-SD/TPGS (1/8/1) solid dispersion significantly improved oral absorption of sirolimus. E-SD significantly inhibited the degradation of sirolimus in a dose-dependent manner. E-SD also significantly inhibited the precipitation of sirolimus compared to hydroxypropylmethyl cellulose (HPMC). Therefore, the results from the present study suggest that the sirolimus-loaded E-SD/TPGS solid dispersion has great potential in clinical applications.

Sinus augmentation using BMP-2 in a bovine hydroxyapatite/collagen carrier in dogs.

AIM: The objective of this study was to determine the efficacy of bone morphogenetic protein 2 (BMP-2) in a bovine hydroxyapatite/collagen (BHC) carrier to augment bone formation in a canine nasal sinus model. METHODS: Eight mongrel dogs, approximately 12 months old and 30 kg in weight were used. Following preparation of bilateral sinus access windows, BHC alone (control) or loaded with E. coli-derived BMP-2 at 0.1 mg/ml was implanted in four animals, and BHC loaded with E. coli-derived BMP-2 at 0.5 and 1.5 mg/ml was implanted in four animals. The animals were euthanized at 20 weeks when block sections were obtained for micro-computed tomography and histometric analyses. RESULTS: Total augmented volumes did not differ significantly between groups. Histometric analysis showed significantly enhanced bone formation for the BMP-2 groups compared with control. CONCLUSION: BMP-2 in a BHC carrier, even at the low 0.1-mg/ml concentration, induces osteogenic activity, enhancing local bone formation in a canine sinus model.

Reosseointegration of mechanically disintegrated implants in dogs: mechanical and histometric analyses.

OBJECTIVES: This study evaluated the reosseointegration of implants that had been reinserted following the mechanical disintegration of immature osseointegration in dogs. MATERIALS AND METHODS: Rotationally mobile implants were installed into an oversized drill space in five canine mandibles. After a healing period of 4 weeks, the immature osseointegration of the implant was intentionally disintegrated by the application of a mechanical countertorque and then reinserted at the same site (experimental group); in the control group, the mobile implant remained submerged without any surgical intervention. The animals were euthanized 4 weeks after the disruption of osseointegration. Changes in the implant stability quotient (ISQ) and Periotest value (PTV) were analyzed, and the bone-implant contact (%) was measured histometrically. RESULTS: All experimental and control sites showed successful mechanical stability at 8-week healing period. The mean ISQ was significantly higher in the experimental group than in the control group at 8 weeks (P < 0.01). In histology, immature woven-bone that bridged between the parent bone and the pre-existing residual bone on implant surface could be observed in experimental sites. The mean bone-implant contact was significantly higher in the experimental group than in the control group (P < 0.05). CONCLUSION: Within the limitation of the small sample used in this study, it is concluded that following the mechanical disruption of osseointegration, an implant can be successfully reosseointegrated with unloaded and submerged healing for a certain period.

Secondary stability of microthickness hydroxyapatite-coated dental implants installed without primary stability in dogs.

OBJECTIVES: The objective of this study was to evaluate the secondary stability of microthickness hydroxyapatite (HA)-coated implants placed without primary stability in dogs. MATERIALS AND METHODS: A total of 48 implants were placed in six dogs. The groups were divided according to the absence or presence of primary stability and healing periods (4 and 8 weeks). Two implants for histological analysis and removal torque test in experimental group were placed without primary stability, showing rotational movement. The other two implants in control group were placed with primary stability. Mechanical test values and histometric measurements were analyzed. RESULTS: The experimental group showed significant increase in a time-dependent manner, while the mean values of the control group were constant in the mechanical tests. The HA layer remained intact, and substantial bone fragments were attached on the surface of the retrieved implant. All implants appeared to be in intimate contact with the host bone and without any inflammation after both 4 and 8 weeks of healing in histology. CONCLUSION: The HA-coated implants exhibited mechanically and histometrically comparable osseointegration after 4 weeks of healing, regardless of primary stability, and the HA-coating layer demonstrated high resistance to exfoliation.

Preparation and evaluation of solid dispersion of atorvastatin calcium with Soluplus® by spray drying technique.

The aim of the present study was to investigate the effect of Soluplus® on the solubility of atorvastatin calcium and to develop a solid dispersion formulation that can improve the oral bioavailability of atorvastatin calcium. We demonstrated that Soluplus® increases the aqueous solubility of atorvastatin calcium. Several solid dispersion formulations of atorvastatin calcium with Soluplus® were prepared at various drug : carrier ratios by spray drying. Physicochemical analysis demonstrated that atorvastatin calcium is amorphous in each solid dispersion, and the 2 : 8 drug : carrier ratio provided the highest degree of sustained atorvastatin supersaturation. Pharmacokinetic analysis in rats revealed that the 2 : 8 dispersion significantly improved the oral bioavailability of atorvastatin. This study demonstrates that spray-dried Soluplus® solid dispersions can be an effective method for achieving higher atorvastatin plasma levels.

Anatomical topography of the mandibular symphysis in the Korean population: a computed tomography analysis.

The objective of this study was to reveal the topography of the mandibular symphysis according to gender and age in the Korean population using computed tomography (CT) to provide a mean anatomical database for the safety zone during block bone harvesting. The following parameters were measured in CT images taken from Korean subjects: interforaminal distance (ID), vertical distance between the inferior mandibular border and the apices of the anterior teeth (VD), and horizontal distance between the labial cortical bone and the apices of the anterior teeth (HD). Differences between genders and among age groups, and the correlations among measurements were analyzed. A total of 973 images (411 males and 562 females; mean age = 41.2 years) were selected. The overall mean ID, VD, and HD were 55.38 ± 5.13, 22.16 ± 3.84 and 5.21 ± 1.70 mm, respectively. The ID and VD were significantly larger in males than in females (P < 0.001), and ID was significantly smaller in the youngest age group than in other age groups (P < 0.001), while HD differed significantly only between the youngest and oldest groups (P < 0.05). There was a weak positive correlation between ID and HD (γ > 0.10). This study provides information on the topography of the mandibular symphysis in the Korean population based on a large number of CT images. In general, gender seemed to influence the symphyseal dimensions strongly, whereas the influence of age was limited.

Formulation, characterization, and in vivo evaluation of celecoxib-PVP solid dispersion nanoparticles using supercritical antisolvent process.

The aim of this study was to develop celecoxib-polyvinylpyrrolidone (PVP) solid dispersion nanoparticles with and without surfactant using the supercritical antisolvent (SAS) process. The effect of different surfactants such as gelucire 44/14, poloxamer 188, poloxamer 407, Ryoto sugar ester L1695, and d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) on nanoparticle formation and dissolution as well as oral absorption of celecoxib-PVP K30 solid dispersion nanoparticles was investigated. Spherical celecoxib solid dispersion nanoparticles less than 300 nm in size were successfully developed using the SAS process. Analysis by differential scanning calorimetry and powder X-ray diffraction showed that celecoxib existed in the amorphous form within the solid dispersion nanoparticles fabricated using the SAS process. The celecoxib-PVP-TPGS solid dispersion nanoparticles significantly enhanced in vitro dissolution and oral absorption of celecoxib relative to that of the unprocessed form. The area under the concentration-time curve (AUC0→24 h) and peak plasma concentration (Cmax) increased 4.6 and 5.7 times, respectively, with the celecoxib-PVP-TPGS formulation. In addition, in vitro dissolution efficiency was well correlated with in vivo pharmacokinetic parameters. The present study demonstrated that formulation of celecoxib-PVP-TPGS solid dispersion nanoparticles using the SAS process is a highly effective strategy for enhancing the bioavailability of poorly water-soluble celecoxib.

Kinetic Modeling for BT200 to Predict the Level of Plasma-Derived Coagulation Factor VIII in Humans.

Lack of Factor VIII (FVIII) concentrates is one of limiting factors for Hemophilia A prophylaxis in resource-limited countries. Rondaptivon pegol (BT200) is a pegylated aptamer and has been shown to elevate the level of von Willebrand Factor (VWF) and FVIII in previous studies. A population pharmacokinetic model for BT200 was built and linked to the kinetic models of VWF and FVIII based on reasonable assumptions. The developed PK/PD model for BT200 described the observed kinetic of BT200, VWF, and FVIII in healthy volunteers and patients with mild-to-moderate hemophilia A from two clinical trials. The developed model was evaluated using an external dataset in patients with severe hemophilia A taking recombinant FVIII products. The developed and evaluated PK/PD model was able to describe and predict concentration-time profiles of BT200, VWF, and FVIII in healthy volunteers and patients with hemophilia A. Concentration-time profiles of FVIII were then predicted following coadministration of plasma-derived FVIII concentrate and BT200 under various dosing scenarios in virtual patients with severe hemophilia A. Plasma-derived products, that contain VWF, are more accessible in low-resource countries as compared to their recombinant counterparts. The predicted time above 1 and 3 IU/dL FVIII in one week was compared between scenarios in the absence and presence of BT200. A combination dose of 6 mg BT200 once weekly plus 10 IU/kg plasma-derived FVIII twice weekly maintained similar coverage to a 30 IU/kg FVIII thrice weekly dose in absence of BT200, representing only 22% of the FVIII dose per week.

Green synthesis of silver nanoparticles-capped aminated lignin as a robust active catalyst for dye discoloration.

Considering the severity of global environmental issues, biomass-derived products have received significant attention as alternatives to foster sustainability and eco-friendliness. The use of metal nanoparticle catalysts for dye decomposition is emerging as a promising approach for environmentally friendly dye removal. In this study, an aminosilane-modified lignin (AML)/silver nanoparticle (AgNP) composite was fabricated and used as a hydrogenation catalyst. The AgNPs were well dispersed on the AML surface and formed strong bonds within the AML/AgNP complex. AML also served as an effective reducing and capping agent for Ag(I) ions. The AML/AgNPs were found to be an efficient catalyst with excellent dye degradation ability and easy reusability. Biomass-derived lignin can be used as a reducing and capping agent for metals and this complex can be used as a high-value bio-catalyst for wastewater remediation.

Facile synthesis of iminated lignin for enhanced free radical and lead ion scavenging capabilities.

Kraft lignin (KL) holds significant potential as a renewable resource for the development of innovative materials that are currently not fully utilized. In this study, a novel iminated lignin (IL) was synthesized by grafting primary amine lignin (N-KL) onto salicylaldehyde. The effects of the dosage and reaction temperature on the nitrogen content of N-KL were evaluated. The maximum nitrogen content in N-KL reached to 3.32 %. Characterization by spectroscopy techniques (FT-IR, XPS, and NMR), elemental analysis, and gel permeation chromatography confirmed the imination of lignin. Additionally, the antioxidant activity of the lignin samples was investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability. Moreover, the DPPH radical scavenging capacity of IL-6 (IC50 = 38.6 ± 3.9 µg/mL) was close to that of commercial antioxidant butylated hydroxytoluene (BHT) (IC50 = 37.7 ± 4.5 µg/mL). Furthermore, the adsorption equilibrium results indicated that IL-6 had a maximum uptake of 115.6 mg/g Pb2+, which was 3.2-fold higher than that of KL. Kinetic adsorption experiments suggested that IL-6 adsorption follows a pseudo-second-order model. Therefore, the synthesized iminated lignin is a promising candidate for the development of environmentally friendly materials with applications as an antioxidant and lead-ion adsorbent.

Effectiveness of hemocoagulase, tranexamic acid, and their combination for reducing blood loss in bimaxillary orthognathic surgery: a retrospective study.

Objectives: Orthognathic surgery is a corrective intervention for maxillofacial deformities. Bleeding is a major concern for oral and maxillofacial surgeons. Various agents, such as hemocoagulase, tranexamic acid, and aprotinin have been developed to reduce intraoperative bleeding and transfusion requirements. Therefore, in this study we aimed to investigate the effects of hemocoagulase and tranexamic acid, as well as their simultaneous use, to reduce bleeding during orthognathic surgery. Patients and. Methods: This retrospective study included patients who had undergone simultaneous orthognathic surgery of the maxilla and mandible between January 2013 and September 2022 and were classified into three groups based on drugs administered: hemocoagulase (Botropase), tranexamic acid, and a combination of both drugs. We recorded patient age, sex, weight, blood loss, and duration of surgery. Red blood cell (RBC), hemoglobin, hematocrit, and platelet levels were measured before, immediately after, and one day after surgery. Results: No statistically significant differences were found in blood loss, RBC, hemoglobin, hematocrit, or platelet levels between any of the groups. There were no differences in the drug effects between Le Fort I and bilateral mandibular sagittal split osteotomies, with or without double genioplasty. However, there were significant reductions in RBC, hemoglobin, hematocrit, and platelet levels during genioplasty. Conclusion: Tranexamic acid, hemocoagulase, and their combination had similar efficacy in patients who underwent Le Fort Ⅰ and bilateral mandibular sagittal split osteotomies with and without genioplasty.

Preparation and characterization of zwitterion-substituted lignin/Nafion composite membranes.

In this study, a novel zwitterion-substituted lignin (ZL) containing amino and sulfonic acid groups was synthesized, and ZL/Nafion composite membranes were fabricated as proton exchange membranes. Kraft lignin was modified using an aminosilane and 1,3-propanesultone via a continuous grafting reaction to provide zwitterionic moieties. Chemical structural analyses confirmed the successful introduction of the zwitterion moiety into lignin. In particular, the surface charge of ZL is positive in an acidic medium and negative in a basic medium, suggesting that ZL is a zwitterionic material. ZL was incorporated into a Nafion membrane to enhance its ion exchange capacity, thermal stability, and hydrophilicity. The proton conductivity of ZL/Nafion 0.5 %, 151.0 mS/cm, was 55.3 % higher than that of unmodified ML (methanol-soluble lignin)/Nafion 0.5 % (97.2 mS/cm), indicating that the zwitterion moiety of ZL enhances the proton transport ability. In addition, oxidative stability evaluation confirmed that ZL/Nafion 2 % was chemically more durable than pure Nafion. This confirmed that using lignin as a membrane additive yielded positive results in terms of chemical durability and oxidation stability in Nafion. Therefore, ZL is expected to be utilized as a multifunctional additive and exhibits the potential for fuel cell applications.

Three-dimensional evaluation of the association between tongue position and upper airway morphology in adults: A cross-sectional study.

Objective: This study aimed to evaluate the association between low tongue position (LTP) and the volume and dimensions of the nasopharyngeal, retropalatal, retroglossal, and hypopharyngeal segments of the upper airway. Methods: A total of 194 subjects, including 91 males and 103 females were divided into a resting tongue position (RTP) group and a LTP group according to their tongue position. Subjects in the LTP group were divided into four subgroups (Q1, Q2, Q3, and Q4) according to the intraoral space volume. The 3D slicer software was used to measure the volume and minimum and average cross-sectional areas of each group. Airway differences between the RTP and LTP groups were analyzed to explore the association between tongue position and the upper airway. Results: No significant differences were found in the airway dimensions between the RTP and LTP groups. For both retropalatal and retroglossal segments, the volume and average cross-sectional area were significantly greater in the patients with extremely low tongue position. Regression analysis showed that the retroglossal airway dimensions were positively correlated with the intraoral space volume and negatively correlated with A point-nasion-B point and palatal plane to mandibular plane. Males generally had larger retroglossal and hypopharyngeal airways than females. Conclusions: Tongue position did not significantly influence upper airway volume or dimensions, except in the extremely LTP subgroup.