Global bibliometric mapping of dental development research for the period 2012-2021.

BACKGROUND: Dental development is a complex long-term biological process, significant attention should be paid to the dental development and health of this critical time window in childhood for the oral health of the whole life cycle. AIM: This study aimed to conduct bibliometric studies on the scientific outputs of global dental development research by the CiteSpace software. DESIGN: The global scientific outputs about dental development between January 1, 2012, and December 31, 2021, retrieved from Web of Science Core Collection, CiteSpace, and Microsoft Excel were applied for this bibliometric study. RESULTS: A total of 3746 reviews and articles were obtained from the Web of Science core database for exploring the basic publication characteristics, hotspots, and frontiers of this research field. The results showed that dental development is gaining more researcher's attention over time. In terms of countries, the USA and China were the major contributors to this research area. At the institutional level, Sichuan University ranked first. Meanwhile, international cooperation across regions was quite active. The Journal of Dental Research has exerted a broad and far-reaching influence on dental development research in both publications and citations. James P Simmer, Jungwook Kim, Charles E Smith, and Jan CC Hu are among the most influential scholars in this field. Finally, the future hotspots were proposed, covering three directions: dental analysis, tooth development, and post-translational phosphorylation of histones. CONCLUSION: In the past decade, the field of dental development has developed rapidly, and the cooperation between scholars, institutions, and researchers has become increasingly close.

NIR-II Imaging-Guided Mitochondrial-Targeting Organic Nanoparticles for Multimodal Synergistic Tumor Therapy.

Effectively interfering energy metabolism in tumor cells and simultaneously activating the in vivo immune system to perform immune attacks are meaningful for tumor treatment. However, precisely targeted therapy is still a huge challenge. Herein, a mitochondrial-targeting phototheranostic system, FE-T nanoparticles (FE-T NPs) are developed to damage mitochondria in tumor cells and change the tumor immunosuppressive microenvironment. FE-T NPs are engineered by encapsulating the near-infrared (NIR) absorbed photosensitizer IR-FE-TPP within amphiphilic copolymer DSPE-SS-PEG-COOH for high-performing with simultaneous mitochondrial-targeting, near-infrared II (NIR-II) fluorescence imaging, and synchronous photothermal therapy (PTT) /photodynamic therapy (PDT) /immune therapy (IMT). In tumor treatment, the disulfide in the copolymer can be cleaved by excess intracellular glutathione (GSH) to release IR-FE-TPP and accumulate in mitochondria. After 808 nm irradiation, the mitochondrial localization of FE-T NPs generated reactive oxygen species (ROS), and hyperthermia, leading to mitochondrial dysfunction, photoinductive apoptosis, and immunogenic cell death (ICD). Notably, in situ enhanced PDT/PTT in vivo via mitochondrial-targeting with FE-T NPs boosts highly efficient ICD toward excellent antitumor immune response. FE-T NPs provide an effective mitochondrial-targeting phototheranostic nanoplatform for imaging-guided tumor therapy.

Recanalization of Xen45 gel stent implant occlusion using 10 - 0 nylon suture in refractory glaucoma: a case report.

BACKGROUND: Xen Gel Stent implant is a new minimally invasive surgical treatment for glaucoma that has been proven effectiveness and safety profile. However, it may also lead to some complications. Xen Gel Stent occlusion is a relatively rare complication reported less frequently and has limited treatment experience. In our case report, we proposed a novel surgical treatment using a 10 - 0 nylon suture to successfully recanalize the occluded Xen45 Gel Stent. CASE PRESENTATION: A 16-year-old female patient had bilateral juvenile glaucoma for the past 5 years. Her right eye had undergone three glaucoma surgeries but failed. At a presentation to our hospital, the right eye's intraocular pressure (IOP) was 30 mmHg despite applying four different active principles. Xen45 Gel Stent implant was chosen for treatment, but six days after implantation, the IOP rose to 40 mmHg as a result of an anterior chamber tip occlusion of the Xen45 Gel Stent. Nd: YAG laser shockwave therapy was attempted but failed. The patient eventually had to return to the operating room for a revision procedure. The Xen45 Gel Stent was recanalized from the ab externo by making an L-shaped conjunctival incision at the fornix base and threading a 10 - 0 nylon suture through it. The IOP was successfully controlled in the 11-month follow-up without medication. CONCLUSION: If postoperative occlusion arises after Xen45 Gel Stent implantation, surgery using 10 - 0 nylon suture to recanalize Xen45 Gel Stent should be considered as a relatively safe, effective that does not require removal of Xen45 Gel Stent.

Global occurrence, drivers, and environmental risks of microplastics in marine environments.

With an increasing quantity of plastic waste being discharged into the oceans, marine microplastic (MP) pollution has received widespread attention. However, the global occurrence characteristics, environmental risks, driving factors, and source-sink relationships remain unclear. In this study, we conducted a meta-analysis based on 165 articles about marine MP pollution. It was found that the global marine MP abundance displayed a significant spatial heterogeneity, and the distribution pattern was influenced by offshore distance, population density, and economic development. The morphological characteristics of MPs showed a significant difference between seawater and marine sediment, and small-size MPs (<1 mm) accounted for the majority of all MPs in the marine environment. The environmental risk assessment revealed that most of the marine MP pollution still remains at low concentrations in the global context, with the Polyurethane (PU), Polyacrylonitrile (PAN), and Polyvinyl chloride (PVC) types of MPs showing high environmental-risk contributions. In addition, land-based waste and marine operations, which were considered to be the dominant sources of marine MPs, primarily aggregated at nearshore submarine areas, in the water column, and in the deep-sea bottom environment. This study suggested that the combination of a meta-analysis and Monte Carlo simulation can provide much valuable information regarding the global occurrence characteristics and environmental risks of marine MPs.

Identification of Oak-Barrel and Stainless Steel Tanks with Oak Chips Aged Wines in Ningxia Based on Three-Dimensional Fluorescence Spectroscopy Combined with Chemometrics.

With the increased incidence of wine fraud, a fast and reliable method for wine certification has become a necessary prerequisite for the vigorous development of the global wine industry. In this study, a classification strategy based on three-dimensional fluorescence spectroscopy combined with chemometrics was proposed for oak-barrel and stainless steel tanks with oak chips aged wines. Principal component analysis (PCA), partial least squares analysis (PLS-DA), and Fisher discriminant analysis (FDA) were used to distinguish and evaluate the data matrix of the three-dimensional fluorescence spectra of wines. The results showed that FDA was superior to PCA and PLS-DA in classifying oak-barrel and stainless steel tanks with oak chips aged wines. As a general conclusion, three-dimensional fluorescence spectroscopy can provide valuable fingerprint information for the identification of oak-barrel and stainless steel tanks with oak chips aged wines, while the study will provide some theoretical references and standards for the quality control and quality assessment of oak-barrel aged wines.

Influence of life-style factors, including second-hand smoke, on dental caries among 3-year-old children in Wuxi, China.

AIM: To examine the association of life-style factors, including second-hand smoke, with dental caries among 3-year-old children in Wuxi, China. METHODS: A multi-stage stratified random cluster sampling method was used, and 283 children were recruited. The prevalence of dental caries was 29.3% (83/283). RESULTS: Univariate analysis indicated that the possible related factors of dental caries included sleep duration, interest in snacks, candy, exposure to second-hand smoke and weight of birth (all P < 0.05). Meanwhile, multivariate logistic regression analysis suggested that children who had used fluoride were less susceptible to dental caries than those who had not used fluoride before (P < 0.05). Moreover, the risk of dental caries in children who were very interested in snacks was greater than those with little interest in snacks (P < 0.05). CONCLUSIONS: Life-style behaviours are crucial factors and should attract enough attention. There might be a potential negative effect of second-hand smoke on the deciduous caries, but it still requires further studies. A co-ordinated effort by health-care providers, policymakers and health institutions has successfully improved children's oral health and the awareness of hygiene knowledge among citizens in Wuxi city.

Living biofouling-resistant membranes as a model for the beneficial use of engineered biofilms.

Membrane systems are used increasingly for water treatment, recycling water from wastewater, during food processing, and energy production. They thus are a key technology to ensure water, energy, and food sustainability. However, biofouling, the build-up of microbes and their polymeric matrix, clogs these systems and reduces their efficiency. Realizing that a microbial film is inevitable, we engineered a beneficial biofilm that prevents membrane biofouling, limiting its own thickness by sensing the number of its cells that are present via a quorum-sensing circuit. The beneficial biofilm also prevents biofilm formation by deleterious bacteria by secreting nitric oxide, a general biofilm dispersal agent, as demonstrated by both short-term dead-end filtration and long-term cross-flow filtration tests. In addition, the beneficial biofilm was engineered to produce an epoxide hydrolase so that it efficiently removes the environmental pollutant epichlorohydrin. Thus, we have created a living biofouling-resistant membrane system that simultaneously reduces biofouling and provides a platform for biodegradation of persistent organic pollutants.

Reduction in nitrogen fertilizer applications by the use of polymer-coated urea: effect on maize yields and environmental impacts of nitrogen losses.

BACKGROUND: Urea is commonly over-applied as a nitrogen (N) fertilizer to crops in southern China and has a low utilization efficiency as a result of the high precipitation and high temperatures in this region. This has led to a need to optimize the management of N fertilizer use in maize crops on the subtropical hilly uplands of southern China. RESULTS: We investigated the effects of applying different amounts of N in the form of polymer-coated urea (PCU) on the yield of maize and gaseous losses of N from soils in the form of NH3 and N2 O. The field plots used in this trial had zero-added N (0 kg N ha-1 ), the addition of urea (240 kg N ha-1 ) and four levels of fertilization with PCU (1 PCU, 0.9 PCU, 0.8 PCU and 0.7 PCU), which represented a 0%, 10%, 20% and 30% reduction, respectively, in the application of PCU-N relative to the urea plot. Compared to the urea plot, there was little variation in the yield of maize for all the PCU-N treatments, with a significant improvement in the utilization efficiency of N (up to 46.0-51.2%) with a 0-30% reduction in the application of PCU-N. Significant effects in the mitigation of the N2 O emission flux and the accumulation of N2 O-N were observed in the 0.8 PCU and 0.7 PCU plots. The application of PCU-N significantly reduced the flux and total amount of NH3 -N lost to the environment: as the application rate for N decreased by 0-30%, the NH3 loss was significantly reduced by 12.7-36.1%. CONCLUSION: The findings of the present study suggest that the use of PCU could allow a reduction in the application of N of 20-30% compared to traditional agricultural practices in this area with the same yield of maize, although with significantly decreased NH3 and N2 O losses and the increased utilization of N. © 2018 Society of Chemical Industry.

Stiff person syndrome with elevated titers of antibodies against cardiolipin and ß2 glycoprotein 1: a case report and literature review.

We reported a Stiff person syndrome (SPS) patient with elevated autoantibodies against cardiolipin and ß2 glycoprotein 1 but without glutamic acid decarboxylase (GAD) antibodies. A 40-year male was admitted due to limited mouth opening for 1 week. His blood routine, biochemical, infectious diseases, tumor markers, radiographic examinations were all normal. At day 3 (D3) after admission, he developed paroxysmal systemic muscle rigidity. At D6, the on-duty physician occasionally gave oral clonazepam, which effectively relieved the symptom. At D13, the titers of cardiolipin and ß2 glycoprotein 1 autoantibodies elevated but the remaining autoantibodies were all in normal ranges. After clonazepam treatment for 1 week, the symptoms were basically relieved, and the titers of these two antibodies returned to normal range with the relief of symptoms. During the 3 years of follow-up, the symptoms did not present again, and the titers of both antibodies were stable in the normal ranges. He had no tumor and other immune system diseases. In summary, we reported a SPS case with elevated cardiolipin and ß2 glycoprotein 1 autoantibodies. The patient was highly responsive to clonazepam therapy, and had favorable outcome in the 3 years follow-up. Our report is helpful for better understand the heterogeneous feature of SPS.

Titanium Ions Promote Exogenous Calcium-Dependent Calcium Influx in Activated Jurkat T Cells: A Possible Mechanism to Explain Its Immunostimulatory Properties.

Titanium and its alloys have been widely used in dental and orthopedic implants. Owing to the biotribocorrosion behavior of implants in simulated oral environment, Ti(IV) ions could be released into surrounding tissues. Current studies have found that Ti(IV) ions could affect the biological activities of immune cells in adjacent tissues and subsequently jeopardize the long-term performance of implant prostheses. However, the potential mechanism underlying its immunomodulatory properties remains unclear. Calcium signaling has been confirmed to be involved in regulation of lymphocyte immune function. Therefore, we hypothesize that Ti(IV) ions modulated T cell function through the change of intracellular calcium concentrations. This study is aimed at exploring the role of intracellular calcium responses in the modulatory effect of Ti(IV) ions on unactivated and phytohemagglutinin-activated Jurkat T cells. Here, we confirmed that Ti(IV) ions within a certain concentration range induced CD69 expression on both unactivated and activated T cells in our study. Additionally, the combined stimulation with Ti(IV) ions and PHA increased expression of IL-1ß, TNF-α, and RANKL. Furthermore, we found that treatment with Ti(IV) induced a transitory increase in the levels of [Ca2+]i in activated Jurkat cells, dependent on the presence of exogenous calcium. Treatment with different doses of Ti(IV) for 24 h significantly increased the levels of [Ca2+]i in the activated Jurkat cells in a dose-dependent manner, but had little effect in the unactivated cells. Treatment with Ti(IV) did not significantly affect the PLCγ1 activation and inositol-1,4,5-trisphosphate (IP3) secretion in Jurkat cells. Taken together, these data indicated that Ti(IV) enhanced calcium influx during the T cell activation, independent of IP3-mediated intracellular calcium release. Our work provides insights into the mechanism involved in the regulation of lymphocyte behaviors under the effect of Ti(IV) ions, which may help to develop therapeutic strategies for dental implant failures.

Antibiotic prophylaxis for preventing dental implant failure and postoperative infection: A systematic review of randomized controlled trials.

PURPOSE: To investigate whether prophylactic antibiotics are beneficial on patients undergoing routine dental implant placement procedures and to investigate which administration regimen is the most effective. METHODS: The primary outcome was implant failure; the secondary outcome was postoperative infection. In the fixed-effects model, the Mantel-Haenszel method was used to calculate pooled relative risks (RRs) at 95% confidence intervals (CIs). To determine the outcomes, the quality of available evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). RESULTS: Prophylactic antibiotics significantly decreased the incidence of implant failure (RR, 0.29; 95% CI, 0.15-0.55; P= 0.0002; I2= 0%) but did not decrease infection. There was no statistically significant difference between single preoperative antibiotics (SPA) and preoperative and postoperative antibiotics (PPA) while treating patients with dental implant failure (RR, 1.07; 95% CI, 0.31-3.62; P= 0.92). No statistically significant difference was observed between SPA and PPA when prescribed to treat infection postoperatively (RR, 1.05; 95% CI, 0.29-3.85; P= 0.94; I2= 0%). CLINICAL SIGNIFICANCE: The administration of prophylactic antibiotics significantly reduced the failure of dental implants under ordinary conditions. Furthermore, single preoperative antibiotics and preoperative and postoperative antibiotics had similar effects on dental implant failures and infections.

Biomaterial Strategies for Immunomodulation.

Strategies to enhance, suppress, or qualitatively shape the immune response are of importance for diverse biomedical applications, such as the development of new vaccines, treatments for autoimmune diseases and allergies, strategies for regenerative medicine, and immunotherapies for cancer. However, the intricate cellular and molecular signals regulating the immune system are major hurdles to predictably manipulating the immune response and developing safe and effective therapies. To meet this challenge, biomaterials are being developed that control how, where, and when immune cells are stimulated in vivo, and that can finely control their differentiation in vitro. We review recent advances in the field of biomaterials for immunomodulation, focusing particularly on designing biomaterials to provide controlled immunostimulation, targeting drugs and vaccines to lymphoid organs, and serving as scaffolds to organize immune cells and emulate lymphoid tissues. These ongoing efforts highlight the many ways in which biomaterials can be brought to bear to engineer the immune system.

Impact of Adjuvants on the Immunogenicity and Efficacy of Split-Virion H7N9 Vaccine in Ferrets.

BACKGROUND: An effective vaccine is urgently needed against the H7N9 avian influenza virus. We evaluated the immunogenicity and protective efficacy of a split-virion H7N9 vaccine with or without the oil-in-water adjuvants in ferrets. METHODS: Ferrets were vaccinated with 2 doses of unadjuvanted, MF59 or AS03-adjuvanted A/Shanghai/2/2013 (H7N9) vaccine, and the induction of antibodies to hemagglutinin (HA) or neuraminidase proteins was evaluated. Ferrets were then challenged with wild-type H7N9 virus to assess the vaccine's protective efficacy. The vaccine composition and integrity was also evaluated in vitro. RESULTS: Adjuvanted vaccines stimulated robust serum antibody titers against HA and neuraminidase compared with the unadjuvanted vaccines. Although there was a difference in adjuvanticity between AS03 and MF59 at a lower dose (3.75 µg of HA), both adjuvants induced comparable antibody responses after 2 doses of 15 µg. On challenge, ferrets that received adjuvanted vaccines showed lower viral burden than the control or unadjuvanted vaccine group. In vitro examinations revealed that the vaccine contained visible split-virus particles and retained the native conformation of HA recognizable by polyclonal and monoclonal antibodies. CONCLUSIONS: The adjuvanted H7N9 vaccines demonstrated superior immunogenicity and protective efficacy against H7N9 infection in ferrets and hold potential as a vaccination regimen.

Relationship between the position of the mental foramen and the anterior loop of the inferior alveolar nerve as determined by cone beam computed tomography combined with mimics.

OBJECTIVE: The position of the mental foramen and the anterior loop length of the inferior alveolar nerve serve as important anatomical landmarks for surgical procedures in the anterior mandibular region. The purpose of this study was to determine the relationship between the anterior loop of the inferior alveolar nerve and the mental foramen by combining cone beam computed tomography and Mimics, a software used to construct 3-dimensional (3D) interactive models of anatomical structures. METHODS: Cone beam computed tomography images from a total of 60 patients were obtained and studied using GALAXY viewer or were imported into Mimics. The anterior loop of the inferior alveolar nerve was reconstructed 3-dimensionally, and then relevant parameters were measured. RESULTS: The parameters were measured, and their values include mean (SD) anterior loop length, 1.16 (1.78) mm; anterior loop angle, 19.13 (26.89) degrees; inferior alveolar canal diameter, 3.01 (0.67) mm; height of the inferior alveolar canal, 10.32 (1.56) mm; 2-dimensional mental foramen diameter, 2.97 (0.61) mm; 3D mental foramen diameter, 2.95 (0.59) mm; 2-dimensional vertical height of the mental foramen, 14.67 (1.67) mm; and 3D vertical height of the mental foramen, 14.61 (1.69) mm. The mental foramen was located apically between the first and second premolars in 51.67% and below the second premolar in 40.83% of the cases. CONCLUSIONS: A relationship was observed between the location of the mental foramen and the presence of the anterior loop of the inferior alveolar nerve. We highlight the effectiveness of cone beam computed tomography and 3D reconstruction in the identification of important anatomical structures relevant for preoperative assessment for surgical procedures in the anterior region of the mandible.

Smart chemistry in polymeric nanomedicine.

This review provides an overview of smart chemistry developed and utilized in the last 5-10 years in polymer-based drug delivery nanomedicine. Smart chemistry not only facilitates the controlled drug loading in a highly specific manner, but also potentially controls the drug release kinetics at the targeted tissues. This review highlights the emergence of new chemistry or unique utilization of conventional chemistry in drug delivery, which is believed to play an important role in developing next generation nanomedicine.

Risk of osteonecrosis of the jaw in cancer patients receiving denosumab: a meta-analysis of seven randomized controlled trials.

AIMS: The aim of this study is to gain a better understanding of the overall incidence and risk of osteonecrosis of the jaw (ONJ) in cancer patients receiving denosumab. METHODS: We performed a meta-analysis of relevant randomized controlled trials identified in Pubmed, Embase, and Cochrane databases. Abstracts presented at the conferences were also searched. Overall incidence rates, relative risk (RR), and 95 % confidence intervals (CI) were calculated employing fixed- or random-effects models depending on the heterogeneity of the included trials. RESULTS: A total of 8963 patients with a variety of solid tumors from 7 randomized controlled trials (RCTs) were included for the meta-analysis. The overall incidence of ONJ in cancer patients receiving denosumab was 1.7 % [95 % CI: 0.9-3.1 %]. Also, the use of denosumab was associated with significantly increased risk of ONJ in comparison with bisphosphonates (BPs)/placebo treatment (RR 1.61, 95 % CI: 1.05-2.48, P = 0.029). Subgroup analysis based on controlled therapies demonstrated an increased risk of ONJ in denosumab therapy, when compared with BPs (RR 1.48, 95 % CI: 0.96-2.29, P = 0.078) or placebo (RR 16.28, 95 % CI: 1.68-158.05, P = 0.017). Similar results were observed in prostate cancer (RR 3.358, 95 % CI: 1.573-7.166, P = 0.002) while there was a non-significantly increased risk of denosumab-related osteonecrosis of the jaw (DONJ) in non-prostate cancers (RR 1.142, 95 % CI: 0.678-1.921, P = 0.618). CONCLUSIONS: The use of denosumab is associated with an increased risk of developing ONJ when compared with BP treatment or placebo, although the increased risk was not statistically significant between denosumab and BP treatment. Further studies are still needed to establish guidelines for the prevention and effective treatment of ONJ.

Translocation of HIV TAT peptide and analogues induced by multiplexed membrane and cytoskeletal interactions.

Cell-penetrating peptides (CPPs), such as the HIV TAT peptide, are able to translocate across cellular membranes efficiently. A number of mechanisms, from direct entry to various endocytotic mechanisms (both receptor independent and receptor dependent), have been observed but how these specific amino acid sequences accomplish these effects is unknown. We show how CPP sequences can multiplex interactions with the membrane, the actin cytoskeleton, and cell-surface receptors to facilitate different translocation pathways under different conditions. Using "nunchuck" CPPs, we demonstrate that CPPs permeabilize membranes by generating topologically active saddle-splay ("negative Gaussian") membrane curvature through multidentate hydrogen bonding of lipid head groups. This requirement for negative Gaussian curvature constrains but underdetermines the amino acid content of CPPs. We observe that in most CPP sequences decreasing arginine content is offset by a simultaneous increase in lysine and hydrophobic content. Moreover, by densely organizing cationic residues while satisfying the above constraint, TAT peptide is able to combine cytoskeletal remodeling activity with membrane translocation activity. We show that the TAT peptide can induce structural changes reminiscent of macropinocytosis in actin-encapsulated giant vesicles without receptors.

Deciphering peri-implantitis: Unraveling signature genes and immune cell associations through bioinformatics and machine learning.

Early diagnosis of peri-implantitis (PI) is crucial to understand its pathological progression and prevention. This study is committed to investigating the signature genes, relevant signaling pathways and their associations with immune cells in PI. We analyzed differentially expressed genes (DEGs) from a PI dataset in the gene expression omnibus database. Functional enrichment analysis was conducted for these DEGs. Weighted Gene Co-expression Network Analysis was used to identify specific modules. Least absolute shrinkage and selection operator and support vector machine recursive feature elimination were ultimately applied to identify the signature genes. These genes were subsequently validated in an external dataset. And the immune cells infiltration was classified using CIBERSORT. A total of 180 DEGs were screened from GSE33774. Weighted Gene Co-expression Network Analysis revealed a significant association between the MEturquoise module and PI (cor = 0.6, P < .0001). Least absolute shrinkage and selection operator and support vector machine recursive feature elimination algorithms were applied to select the signature genes, containing myeloid-epithelial-reproductive tyrosine kinase, microfibrillar-associated protein 5, membrane-spanning 4A 4A, tribbles homolog 1. In the validation on the external dataset GSE106090, all these genes achieved area under curve values exceeding 0.95. GSEA analysis showed that these genes were correlated with the NOD-like receptor signaling pathway, metabolism of xenobiotics by cytochrome P450, and arachidonic acid metabolism. CIBERSORT revealed elevated levels of macrophage M2 and activated mast cells in PI. This study provides novel insights into understanding the molecular mechanisms of PI and contributes to advancements in its early diagnosis and prevention.

Tooth pattern, development, and replacement in the yellow catfish, Pelteobagrus fulvidraco.

Studies of teleost teeth are important for understanding the evolution and mechanisms of tooth development, replacement, and regeneration. Here, we used gross specimens, microcomputed tomography, and histological analysis to characterize tooth structure, development, and resorption patterns in adult Pelteobagrus fulvidraco. The oral and pharyngeal teeth are villiform and conical. Multiple rows of dentition are densely distributed and the tooth germ is derived from the epithelium. P. fulvidraco exhibits a discontinuous and non-permanent dental lamina. Epithelial cells surround the teeth and are separated into distinct tooth units by mesenchymal tissue. Tooth development is completed in the form of independent tooth units. P. fulvidraco does not undergo simultaneous tooth replacement. Based on tooth development and resorption status, five forms of teeth are present in adult P. fulvidraco: developing tooth germs, accompanied by relatively immature tooth germs; mature and well-mineralized tooth accompanied by one tooth germ; teeth that have begun resorption, but not completely fractured; fractured teeth with only residual attachment to the underlying bone; and teeth that are completely resorbed and detached. Seven biological stages of a tooth in P. fulvidraco were also described.

Effects of different intrusion patterns during anterior teeth retraction using clear aligners in extraction cases: an iterative finite element analysis.

Background: Overtreatment design of clear aligner treatment (CAT) in extraction cases is currently primarily based on the clinical experience of orthodontists and is not supported by robust evidence on the underlying biomechanics. This study aimed to investigate the biomechanical effects of overtreatment strategies involving different maxillary anterior teeth intrusion patterns during anterior teeth retraction by CAT in extraction cases. Materials and methods: A finite element model of the maxillary dentition with the first premolar extracted was constructed. A loading method of clear aligners (CAs) based on the initial state field was proposed. The iterative method was used to simulate the long-term orthodontic tooth movement under the mechanical load exerted by the CAs. Three groups of CAs were utilized for anterior teeth retraction (G0: control group; G1: incisors intrusion group; G2: anterior teeth intrusion group). Tooth displacement and occlusal plane rotation tendency were analyzed. Results: In G0, CAT caused lingual tipping and extrusion of the incisors, distal tipping and extrusion of the canines, mesial tipping, and intrusion of the posterior teeth. In G1, the incisors showed minimal extrusion, whereas the canines showed increased extrusion and distal tipping tendency. G2 showed the smallest degree of posterior occlusal plane angle rotation, while the inclination tendency of the canines and second premolars decreased. Conclusion: 1. In CAT, tooth displacement tendency may change with increased wear time. 2. During anterior teeth retraction, the incisor intrusion pattern can provide effective vertical control for the lateral incisors but has little effect on the central incisors. Anterior teeth intrusion patterns can alleviate the inclination of canines and second premolars, resulting in partial relief of the roller-coaster effect.