Obesity and temporomandibular joint disorders: a systematic review and meta-analysis.

BACKGROUND: Temporomandibular joint disorders (TMD) is the most common non-dental pain complaint in the maxillofacial region, which presents a variety of symptoms and signs, including temporomandibular joints (TMJ) and masticatory muscle pain, joint noise, tinnitus, headaches, irregular or restricted mandibular function, masticatory difficulty, and restricted mouth opening. When comes to the relationship between obesity and TMD, it has remained controversial and inconsistent, therefore, we first conducted this meta-analysis to estimate the unclear relationship between obesity and TMD. METHODS: Searches were conducted in PubMed, Web of Science, Embase, and Cochrane Library. Subjects were divided into five groups according to BMI level in this study, including the normal weight group: 18.5 ≤ BMI < 25, overweight group: 25 ≤ BMI < 30, obesity group: BMI ≥ 30, control group: BMI < 25, and overweight and obesity group: BMI ≥ 25. Statistics analyses were conducted using Stata (15.0). The number of PROSPERO was CRD42022368315. RESULTS: Eight studies were included in this study, and six articles with a total of 74,056 participants were synthesized for meta-analysis. Compared to normal weight individuals, overweight and obesity together decreased the risk of TMD (OR = 0.66, 95% CI = 0.46-0.95), and it was significantly decreased by obesity alone (OR = 0.58). Moreover, it was lower in obesity compared with control subjects (OR = 0.83, 95% CI = 0.73-0.94). Furthermore, in overweight and obese individuals, it was much lower in obesity than in overweight (OR = 0.82, 95% CI = 0.71-0.94). CONCLUSIONS: Obesity is not a risk factor for TMD, and maybe a protective factor for TMD, of which patients with larger BMI are less likely to suffer from TMD pain. Therefore, the value of BMI should be taken into consideration in the assessment of TMD.

The effect of surface treatments on the color stability of CAD-CAM interim fixed dental prostheses.

STATEMENT OF PROBLEM: Additive manufacturing or 3D printing is gaining popularity in dentistry, including for interim fixed dental prostheses (IFDPs). However, evidence regarding the color stability of 3D-printed IFDPs is lacking. PURPOSE: The purpose of this in vitro study was to investigate whether different surface treatments could affect the color stability of milled and 3D-printed IFDPs after simulated physiological aging. MATERIAL AND METHODS: Forty milled IFDPs were fabricated with a 5-axis dental mill (DWX-51D; Roland DGA Corp) from polymethyl methacrylate disks (Temp Esthetic 98, A3.5, 98.5×16 mm; Harvest Dental Products, LLC). Forty 3D-printed IFDPs were fabricated with an in-office digital light processing 3D printer (MAX; Asiga) and light-polymerizing resin (NextDent Crown & Bridge A3.5; NextDent B.V). All milled and 3D-printed IFDPs were allocated into 4 different groups (n=10), according to different surface treatments: Control, Polish, Optiglaze, and Skinglaze. In the Control group, no surface treatment was applied to the IFDPs. For the Polish group, IFDPs were finished and polished with aluminum oxide finishers/polishers (Enhance PoGo Complete Kit; Dentsply Sirona). For the Optiglaze and Skinglaze groups, specimens were first finished and polished and prepared with additional light-polymerizing protective coatings (Optiglaze; GC America Inc, or New Outline Skin Glaze; anaxdent North America). Shade measurements were recorded with a digital spectrophotometer (Vita Easyshade V; VITA North America) before and after the thermocycling for the color stability comparisons. The effects of interim prosthesis type and surface treatments on ΔE∗, ΔL∗, Δa∗, and Δb∗ were examined using 2-way analysis of variance (ANOVA), and ΔE∗ was considered as the primary outcome variable. Post hoc pairwise comparisons were performed by using the Tukey honestly significant difference (HSD) method (α=.05 for all tests). RESULTS: Milled IFDPs had significantly smaller ΔE∗ than 3D-printed prostheses for the Control group only (P<.001). Within the milled IFDPs, Optiglaze group (mean ±standard deviation, 1.01 ±0.38) had significantly lower ΔE∗ than all the other surface treatments groups (Control group: 2.38 ±0.44, P<.001; Polish group: 1.83 ±0.51, P=.025; and Skinglaze group: 1.85 ±0.78, P=.021). Within the 3D-printed IFDPs, the Control group (3.83 ±0.71) had significantly larger ΔE∗ than all other surface treatments (Polish group: 2.66 ±0.89, P=.018; Skinglaze group: 1.40 ±0.73, P<.001; and Optiglaze group: 1.37 ±0.67, P<.001). The Polish group had significantly higher ΔE∗ than Skinglaze group (P=.009) and Optiglaze group (P=.007), while Skinglaze and Optiglaze groups were not significantly different from each other (P=1.000). CONCLUSIONS: For the milled IFDPs, only the nano-filled, light-polymerizing protective coating significantly lowered color changes after thermocycling simulating 6 months of intraoral physiological aging. For the 3D-printed IFDPs, surface polishing and both light-polymerizing protective coating agents all significantly reduced color changes of the prostheses after thermocycling. The protective effect of light-polymerizing coating agents was more substantial.

Association between smoking and Schneiderian membrane perforation during maxillary sinus floor augmentation: A systematic review and meta-analysis.

OBJECTIVE: To estimate the association between smoking and Schneiderian membrane perforation in sinus floor augmentation. MATERIALS AND METHODS: Searches were conducted in PubMed, Web of Science, Embase, and Cochrane Library. Data were extracted by two authors independently. The inclusion criteria were the (1) age of patients >18, (2) the number of participants >10, and (3) smoking and the patients of Schneiderian membrane perforation were accurately recorded. The risk of bias was assessed by the Newcastle-Ottawa scale (NOS). Statistics analyses were conducted using Reman5.4.1 and Stata (15.0). The association of Schneiderian membrane perforation with smoking habits during maxillary sinus floor elevation was expressed as odds ratios (ORs) with a 95% confidence interval (95% CIs). And the I2 statistic was used to estimate statistical heterogeneity. The funnel plot and Egger's tests were used to evaluate the reliability and stability of the results. RESULTS: Of 1463 articles screened, nine studies were included in our systematic review, and eight were synthesized for meta-analysis. Eight were retrospective observational studies and one was a clinical trial, with a total of 1424 patients included. The nine studies were proved as high quality according to the NOS. There was no significant publication bias in the studies (p = 0.827). A random-effects model was used because of differences in the adopted methodologies (p = 0.39, I2  = 5%). During maxillary sinus augmentation, smoking and Schneiderian membrane perforation were associated (odds ratios, 1.58 [95% CI, 1.10-2.25]). CONCLUSION: Smoking increased the risk of membrane perforation in maxillary sinus floor augmentation. Our evaluation was limited by the poor reporting of the number of cigarettes smoked per day (PROSPERO number was CRD42022306570).

Correlation Analysis between Residual Pain after Vertebral Augmentation and the Diffusion Distribution of Bone Cement: A Retrospective Cohort Study.

Objective: To explore the influence and potential factors of the bone cement dispersion state on residual pain after vertebral augmentation. Methods: The cases included in this retrospective cohort study were patients treated with vertebral augmentation (VA) for osteoporotic vertebral compression fractures (OVCFs) between July 2018 and June 2021. According to the type of cement diffusion distribution, the patients were divided into a sufficient diffusion group (Group A) and an insufficient diffusion group (Group B). The differences in the baseline data, visual analog scale (VAS), Oswestry disability index score (ODI), injured vertebral height (IVH), and local kyphosis angle (LKA) between the two groups were analyzed. Assessments were performed preoperatively on the 2nd day postoperation and at the last follow-up. The imaging data of injured vertebrae were accurately reconstructed by a GE AW4.7 workstation, and the differences in the vertebral body volume, bone cement volume, and bone cement volume ratio were compared between the groups. Result: After screening, 36 patients were included. (1) The postoperative VAS and ODI scores of the two groups were significantly improved compared with the preoperative scores. (2) On the 2nd day postoperation and the last follow-up, the VAS and ODI scores of Group A were significantly different from those of Group B, and Group A outperformed Group B. (3) The IVH and LKA of the two groups were improved after the operation, and no significant difference was found between the groups. (4) Significant differences were found in the bone cement volume and bone cement volume ratio between the groups, and Group A was larger than Group B. Conclusions: Sufficient bone cement diffusion can reduce residual pain after vertebral augmentation.

Toxicological effects of micro/nano-plastics on mouse/rat models: a systematic review and meta-analysis.

Micro/nano-plastics (MNPs) are considered a heterogeneous class of environmental contaminants that cause multiple toxic effects on biological species. As the commonly used mammalian models to study the effects of MNPs with regard to their toxic effects, the mouse and rat models are making a great contribution to the disciplines of environmental toxicology and medical health. However, the toxic effects of MNPs have not been systematically summarized. Therefore, a systematic review and a meta-analysis of the toxic effects of MNPs on mouse/rat models were conducted. A total of seven main categories were established in this systematic review, and 24 subcategories were further divided according to the specific physiological significance of the endpoint or the classification of the physiological system, which covered all the selected pieces of literature. A total of 1,762 biological endpoints were found, and 52.78% of them were significantly affected. This fact indicates that there are relative factors, including the size, polymer type, concentration, and exposure time of MNPs and different sexes of mouse/rat models that could significantly affect the biological endpoints. These biological endpoints can be classified into various factors, such as the dose-response relationships between MNP concentration and physiological categories of the nervous system, growth, reproduction, digestive tract histopathology, and inflammatory cytokine level, among others. MNPs negatively affected the blood glucose metabolism, lipid metabolism, and reproductive function in mice. The reproductive function in male mice is more sensitive to the toxic effects of MNPs. These findings also provide insights into and directions for exploring the evidence and mechanisms of the toxic effects of MNPs on human health. It is clear that more research is required on the pathological mechanisms at the molecular level and the long-term effects of tissue accumulation.

Hypoxia-mimicking cobalt-doped multi-walled carbon nanotube nanocomposites enhance the angiogenic capacity of stem cells from apical papilla.

Adequate and timely vascularization is crucial for the success of dental pulp tissue engineering. Hypoxia, an important driving force of angiogenesis, plays an important role in this process. However, few studies have investigated the fabrication of hypoxia-simulating biomaterials for dental applications. In this study, a novel hypoxia-mimicking, multi-walled carbon nanotubes/cobalt (MWCNTs/Co) nanocomposite was prepared using the metal-organic framework (MOF) route for the in situ insertion of MWCNTs into Co3O4 polyhedra. The obtained nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Cobalt ion release of MWCNTs/Co was analyzed in vitro. Cell viability and proliferation were assessed by culturing stem cells from apical papilla (SCAP) with MWCNTs/Co nanocomposites. The angiogenic capacity of SCAP after exposure to nanocomposites was evaluated by enzyme-linked immunosorbent assay (ELISA), western blotting and the Matrigel angiogenesis assay. Our results proved that the synthesized MWCNTs/Co nanocomposites possessed a well-designed connecting structure and could release cobalt ions in a sustained way. The MWCNTs/Co nanocomposites at 50 µg/mL significantly upregulated hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) protein expression in SCAP, with no apparent cellular cytotoxicity. The conditioned medium collected from SCAP treated with MWCNTs/Co markedly promoted endothelial cells vessel formation. In conclusion, hypoxia-mimicking MWCNTs/Co nanocomposites exhibit promising angiogenic potential for dental tissue engineering and might provide an alternative solution for translational applications.

Chemical Sympathectomy Impairs Peri-implant Osseointegration in Mice: Role of the Sympathetic Nervous System in Osseointegration.

PURPOSE: The possibility that the sympathetic nervous system (SNS) controls bone remodeling has been raised; however, the actual function of the SNS in osseointegration is still unknown. This study aimed to investigate the effect of chemical sympathectomy on peri-implant osseointegration in adult mice. MATERIALS AND METHODS: Forty C57BL/6J mice (8-week-old) were divided into two groups: a sympathectomy group and a control group, which were administered 6-hydroxydopamine and saline, respectively, by intraperitoneal injection for 5 days. Then, the mice were exposed to implant surgery. Analyses of serum chemistry, microcomputed tomography, biomechanical test, and bone histomorphometry were employed at 2 and 4 weeks. RESULTS: Compared with the control, the chemical sympathectomy group had a higher serum level of C-terminal collagen I cross-links but lower serum osteocalcin. After 4 weeks, peri-implant trabecular microstructure, including trabecular volume, trabecular thickness, the percentage of osseointegration, and bone-to-implant contact, was lower; however, the trabecular separation was higher in the sympathectomy group mice in comparison with the control group. In addition, the strength of bone-titanium integration measured by the biomechanical resistance test was lower. Furthermore, histomorphologic evidence revealed that the osteoclast counts were higher in the sympathectomy group, while the mineral apposition rate and the bone formation rate per bone surface were significantly lower. CONCLUSION: Within the limitations of this experimental study, the data showed that chemical sympathectomy has a negative effect in peri-implant osseointegration, suggesting that the SNS may need to be taken into consideration in terms of peri-implant bone healing.

Combination Use of BMP2 and VEGF165 Promotes Osseointegration and Stability of Titanium Implants in Irradiated Bone.

BACKGROUND: Clinical data demonstrated that failure rate of titanium implant in irradiated bone was 2-3 times higher than that in nonirradiated bone and it is difficult to get the ideal results in irradiated bone. PURPOSE: The aim of the study was to investigate the effects of HBO, BMP2, VEGF165, and combined use of BMP2/VEGF165 on osseointegration and stability of titanium implant in irradiated bone. MATERIALS AND METHODS: Sixty rabbits were randomly assigned to 5 groups (control group, HBO group, VEGF165 group, BMP2 group, and BMP2/VEGF165 group) after receiving 15 Gy radiation. Implant surgery was performed on tibias eight weeks later. They were sacrificed at two or eight weeks after operation. Implant stability, calcium, and ALP activity in serum, the ratio of bone volume to total volume, the rate of bone growth, and gene expression were assessed. RESULT: There was no mortality and no implants failed during the experiment. Implant stability was significantly compromised in the control group compared to the other four experimental groups, and the BMP2/VEGF165 group had the highest implant stability. HBO, BMP2, and VEGF165 significantly increased BV/TV and the rate of bone growth, while the BMP2/VEGF165 showed the best effect among groups. The expression of RUNX2 in HBO, BMP2, and VEGF165/BMP2 group was higher than that in the VEGF165 and control groups at two weeks. The expression of OCN in HBO, BMP2, VEGF165, and VEGF165/BMP2 groups was higher than that in the control group, and the gene expression of CD31 was higher in HBO, VEGF165, and BMP2/VEGF165 groups than that in control and BMP2 groups. CONCLUSION: HBO, BMP2, and VEGF165 could increase bone formation around the implant and improved the implant stability in irradiated bone. The combination use of BMP2 and VEGF165 may be promising in the treatment of implant patients with radiotherapy.

Effect of lentiviral vector overexpression α-calcitonin gene-related peptide on titanium implant osseointegration in α-CGRP-deficient mice.

α-Calcitonin gene-related peptide (α-CGRP) plays a significant pathophysiological role in bone development, metabolism and remodeling around dental implants. However, the half-life of α-CGRP in plasma is only 10min, which affects its long-time application and an alternative approach should be developed to deliver α-CGRP over long periods of time. The aim of this study is to investigate whether a lentiviral α-CGRP overexpression vector system can express this target-gene longer at peri-implant sites, thus enhancing osseointegration. Animals were divided to the following groups: α-CGRP-/-, α-CGRP-/- with lentivirus transfection and α-CGRP+/+ mice. IVIS Spectrum imaging observations identified the successful transfection of α-CGRP around experimental implants inserted in the femurs at 5days after injection. Histomorphometrical analysis indicated an increase of bone-implant contact (BIC) at 1-month healing in the transfection group. Moreover, real-time RT-PCR and western blot results of bone-related markers Runx2, Osterix, and BSP levels elevated in lentivirus-transfected mice at 21days, compared to the untreated α-CGRP-/- mice. There was no significant difference between the transfection group and α-CGRP+/+ group. Further α-CGRP protein detection confirmed the persistent expression of this transgene at 21days post-operatively. These results suggest that this lentiviral vector system expresses α-CGRP in an effective, appropriate and sustained manner, which might have a potential application in enhancing titanium implant osseointegration.

Composite scaffolds of dicalcium phosphate anhydrate /multi-(amino acid) copolymer: in vitro degradability and osteoblast biocompatibility.

This study aims to evaluate in vitro degradability and osteoblast biocompatibility of dicalcium phosphate anhydrate/multi-(amino acid) (DCPA/MAA) composites prepared by in situ polymerization method. The results revealed that the composites could be slowly degraded in PBS solution, with weight loss of 9.5 ± 0.2 wt.% compared with 12.2 ± 0.2 wt.% of MAA copolymer after eight weeks, and the changes of pH value were in the range of 7.18-7.4 and stabilized at 7.24. In addition, the compressive strength of the composite decreased from 98 to 62 MPa while that of MAA copolymer from 117 to 86 MPa. Furthermore, with non-toxicity demonstrated by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay, the addition of DCPA to the MAA copolymer evidenced an enhancement of osteoblast differentiation and attachment compared with pure MAA materials regarding to alkaline phosphatase activity as well as initial cell adhesion. The results indicated that the DCPA/MAA scaffolds with good osteoblast biocompatibility, degradability, and sufficient strength had promising potential application in bone tissue engineering.

Preparation and preliminary in vitro evaluation of a bFGF-releasing heparin-conjugated poly(ε-caprolactone) membrane for guided bone regeneration.

In an effort to improve guided bone regeneration (GBR), we successfully fabricated a novel basic fibroblast growth factor (bFGF)-releasing heparin-conjugated poly(ε-caprolactone) membrane (hep-PCL/bFGF). This material has a porous microstructure with smooth and rough pore walls before and after heparinization, respectively. Our FTIR analyses indicated that chemical bonds were formed between PCL and heparin with a new amide C=O band at 1660 cm(-1) and a band at 3400 cm(-1) that can be attributed to -OH stretching in cross-linked heparin. We showed that bFGF was released from hep-PCL/bFGF in a continuous pattern, which remained for 3 weeks. We evaluated MG63 cell proliferation and biocompatibility of GBR membrane by a CCK-8 assay and a live/dead assay. The CCK-8 results revealed that the hep-PCL/bFGF group had superiority compared to other groups. Furthermore, cell morphology of hep-PCL membrane exhibited larger projected areas than those of PCL surfaces based on scanning electron microscopy analysis and immunofluorescent staining of cell cytoskeleton and vinculin expression. Our alkaline phosphatase activity assay also confirmed better performance of the hep-PCL/bFGF group. These results suggested that this novel hep-PCL/bFGF membrane is suitable for osteoblast-like cells to attach, proliferate, and differentiate. Therefore, the hep-PCL/bFGF membrane has potential to be a biodegradable membrane for GBR and warrants further investigation.

[Evaluation of clinical therapeutic efficiency of immediate loaded implant].

OBJECTIVE: Clinical cases of immediate loaded implants were retrospectively analyzed, in the aim of evaluating the clinical value of immediate loading. METHODS: From July 2005 to October 2009, 99 immediate loaded implants were implanted in 29 patients. The overall data including radiography, clinical examination were collected during the follow-up periods ranged from 4 to 46 months. The implants were evaluated with the survival rate, bone resorption, soft tissue esthetics (including gingiva papilla index and pink esthetic score). RESULTS: Survival rate for immediate loaded implant was 97.0%. The average bone resorption were 0.22 mm at 4-6 months after surgery, bone increase of 0.15 mm were found at 6-12 month, and bone increase up to 0.16 mm at 12-46 months. The gingival papilla index was 2.68, while pink esthetic score was 12.58. CONCLUSION: Immediate loaded implant is an effective repairing method for patients missing teeth and the esthetics effect is ideal.

Effects of an antibacterial membrane on osteoblast-like cells in vitro.

Infection around membranes is often found in guided bone regeneration (GBR). The excellent antibacterial properties of Ag-nHA-nTiO(2)/polyamide-66 (PA66) nanocomposite membranes have been demonstrated previously. The aim of this study was to observe the microstructure of an Ag-nHA-nTiO(2)/PA66 membrane and its effects on osteoblast-like cells in vitro. An Ag-nHA-nTiO(2)/PA66 membrane was used in the experimental group, and both nHA/PA66 and expanded poly tetrafluroethylene (e-PTFE) membranes were set as control. MG63 osteoblast-like cells were cultured on the three kinds of membrane and tissue culture polystyrene (TCP). The microstructure of the above membranes and the cells adhered on them were detected by scanning electronic microscope (SEM). Cell proliferation was determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, cell viability with a cell viability analyzer, and alkaline phosphatase (ALP) activity and Ca(2+) concentration of osteoblast-like cell matrix by enzyme-linked immunosorbent assay. SEM showed that both Ag-nHA-nTiO(2)/PA66 membranes and nHA/PA66 membranes were composed of porous obverse face and smooth opposite face. The e-PTFE membranes showed elliptic surface structure with many tiny lined cracks. The MG63 cells adhered and proliferated well on all three kinds of membranes. Though cell viability on Ag-nHA-nTiO(2)/PA66 membranes was significantly lower than that of the control groups (P < 0.05), MTT values, ALP activity, and Ca(2+) concentration did not differ significantly among the three kinds of membranes (P > 0.05). From these findings, it can be concluded that Ag-nHA-nTiO(2)/PA66 membranes are as biocompatible as nHA/ PA66 membranes and TCP, thus may be applied safely in GBR.