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Objective To analyze the spatial relationship between the roots of maxillary anterior premolars and the maxillary sinus, thus providing an anatomical basis for timing, planning, surgical approaches, and implant selection at this site. Methods Cone beam CT (CBCT) images were collected from 264 patients (aged 20-65 years) who visited the Ruihua Dental Clinic between January 2017 and March 2023. The minimum distance from the apex of the maxillary anterior premolar roots to the lower wall of the maxillary sinus was measured on the coronal plane. The classification of the vertical relationship between the tooth root and the lower wall of the maxillary sinus was performed, and comparisons were made bilaterally, between genders, and among different age groups. Results The minimum distance (Q50) from the apex of the first maxillary premolar root to the lower wall of the maxillary sinus was 7.34 mm for the single-root type, 7.80 mm for the buccal root of the double-root type, and 7.36 mm for the palatal root. For the second maxillary premolar, the median distance was 2.56 mm for the single root type, 1.73 mm for the buccal root type, and 1.23 mm for the palatal root type. There was a significant difference in the shortest distance from the apex of the right second maxillary premolar single root to the lower wall of the maxillary sinus among the different age groups (PP>0.05). The most common vertical relationship between the apex of the maxillary anterior premolar roots and the lower wall of the maxillary sinus was noncontact. There was no significant difference in the vertical relationship classification between the single-root and double-root types (P>0.05). Conclusion Most maxillary first premolar roots can provide sufficient bone height, which makes it easy to achieve immediate implantation. The maxillary second premolar root frequently involves insufficient bone, which is necessary to make full use of the bone wall of the extraction socket or the sinus floor cortical bone to achieve initial stability. The vertical relationship between the premolar root and maxillary sinus was influenced by age and dental position. Younger age groups often exhibit inadequate bone height, and the indication for immediate implantation should be carefully considered. The number of roots does not significantly affect the relationship between the sinus and root; however, double-rooted premolars offer more support for immediate implantation and socket healing due to the small root diameter and bony separation between the roots.

Objective Exploring the position and bone wall thickness characteristics of the maxillary central incisors in Southern Chinese adults to provide a clinical reference for the design of immediate maxillary central incisor implantation surgery. Methods The hospital ethics committee approved the study, and the patients provided informed consent. CBCT images of 990 adult patients (aged 20-79 years) from the Stomatology Hospital (January 2018 to December 2021) were categorized based on the dental arch form and age-sex groups. Sagittal CBCT images of the maxillary central incisors were used to measure the labial and palatal bone thickness wall at 4 mm the CEJ to apical, the middle of the root, and the angle between the tooth long axis and the long axis of the alveolar process, to compare the thickness of the labial and palatal bone walls in samples of male and female patients, and to explore the relationship between the angle between the tooth long axis and the alveolar process long axis in samples of male and female patients in different age groups (20-39 years; 40-59 years; 60-79 years). Results Significant differences were found in the labiopalatine side of the alveolar bone of the maxillary incisor root position. A total of 95.8% (948/990) of the maxillary incisors were positioned more buccally, 4.1% (41/990) were positioned more midway, and 0.1% (1/990) were positioned more palatally. The thicknesses of the bone wall at the CEJ of 4 mm below the palatal side, the middle of the root, and at the apex were greater (1.82 ± 0.56 mm, 3.20 ± 1.10 mm, and 7.70 ± 2.00 mm, respectively) than those at the labial side (1.21 ± 0.32 mm, 0.89 ± 0.35 mm, and 1.86 ± 0.82 mm, respectively), with statistical significance (P

Objectives: This study investigated the effect of additive manufacturing (AM) methods on the slot height dimensions and accuracy of 3D‐printed orthodontic brackets. Methods: A 3D model of a standard Mclaughlin Bennett Trevisi bracket was used as a reference to print the ceramic bracket in a 90° orientation using two representative AM methods: digital light processing (DLP) and material jetting (MJ). The dimensional accuracy and slot heights were determined using a scanning electron microscope and an optical scanner. Also, all specimens were analysed using the Geomagic Control X 3D inspection software. The root mean square (RMS) values were used for trueness and precision assessment. Statistical analyses were performed using an independent sample t‐test. Results: Slot height dimensions, trueness RMS, and precision RMS were statistically affected by different AM methods (p <.01). There was a significant difference between the different printing methods, with DLP meeting the tolerance requirements (mean slot height = 0.557 ± 0.018 mm) and MJ being slightly below them (mean slot height = 0.544 ± 0.021 mm). However, MJ significantly outperformed DLP in terms of accuracy. Among the two printing methods, MJ was associated with higher trueness (RMS = 0.025 ± 0.004 mm) and precision (RMS = 0.038 ± 0.005 mm). Conclusions: Both tested AM methods yielded clinically acceptable outcomes, with the RMS range set to ±100 μm and the slot height tolerance established at 0.549–0.569 mm. The MJ technology achieved the highest accuracy. [ABSTRACT FROM AUTHOR]

Objective To study the change of STAT1 expression in the anterior cingulate cortex on rats under orth⁃ odontic force, and to further explore the roles of STAT1 and related JAK⁃STAT1 signaling pathway in the mediation and regulation of pain during tooth movement. Methods 112 male Sprague⁃Dawley (SD) rats (225±25 g) were used in this study. They were randomly divided into experimental groups (96 rats) and control groups (16 rats). All rats were in⁃ stalled bilateral maxillary device for tooth movement models. Rats in the experimental groups were applied 80g orth⁃ odontic force on both sides and were divided into six subgroup 4 h, 12 h, 24 h, 2 d, 3 d, 7 d, with 16 rabbits in each subgroup. The control groups were only installed the same orthodontic devices, without the application of orthodontic force. Brain tissue of the anterior cingulate cortex was isolated after 4 h, 12 h, 24 h, 2 d, 3 d, 7 d since experiment, and the expression level of STAT1 and p⁃STAT1 was analyzed with the method of immunofluorescence and PCR. Results For the immunofluorescence result, there was significant difference in STAT1 expression between control groups and dif⁃ ferent experimental groups at different time points in total (P < 0.05). The STAT1 expression amount in the 4 h group decreased significantly when compared with the control group (P < 0.05); to the 2 d group, the difference is still statisti⁃ cally significant (P < 0.01). 3 d group, 7 d group and control group had no statistically significant difference. The STAT1 expression amount in 4 h group, 12 h group, 24 h group was significantly lower than that in 3 d and 7 d groups, differences were statistically significant (P < 0.05). The STAT1 expression in the 2 d group was significantly lower than that of 7 d (42.35 ± 5.77) group, the difference was statistically significant (P < 0.05). There was significant difference in p⁃STAT1 expression between control groups and different experimental groups at different time points in total (F = 623.518, P < 0.05). The p⁃STAT1 expression amount in experimental groups were higher than that in the control group (P < 0.05). The p⁃STAT1 expression in 4 h group was lower than that in 12 h and 24 h group and higher than that in 2 d, 3 d and 7 d groups, of which the differences were statistically significant (P < 0.05). The p⁃STAT1 expression in 12 h group was lower than that in 24 h group and higher than that in 2 d, 3 d and 7 d groups, of which the differences were statistically significant (P < 0.05). For the PCR result, the expression of mRNA in STAT1 of experimental groups of 4 h, 12 h, 24 h, 2 d, 3 d, 7 d and the control groups were not statistically significant (P > 0.05). Conclusions After apply⁃ ing orthodontic force, the expression of STAT1 decreased transiently and the expression of p⁃STAT1 increased transient⁃ ly. The reduction of STAT1 was probably caused by the phosphorylation of STAT1 and decrease in the translation level of STAT1, rather than changes in the transcriptional levels. The orthodontic pain might be related with the activation of STAT1 into phosphorylated STAT1.

External apical root resorption is among the most common risks of orthodontic treatment, and it cannot be completely avoided and predicted. Risk factors causing orthodontic root resorption can generally be divided into patient- and treatment-related factors. Root resorption that occurs during orthodontic treatment is usually detected by radiographical examination. Mild or moderate root absorption usually does no obvious harm, but close attention is required. When severe root resorption occurs, it is generally recommended to suspend the treatment for 3 months for the cementum to be restored. To unify the risk factors of orthodontic root resorption and its clinical suggestions, we summarized the theoretical knowledge and clinical experience of more than 20 authoritative experts in orthodontics and related fields in China. After discussion and summarization, this consensus was made to provide reference for orthodontic clinical practice. [ABSTRACT FROM AUTHOR]

A series of Pt catalysts supported on SO42− group modified Al2O3 were synthesized and tested for methane and propane combustion. The introduction of SO42− group promoted the surface acidity but reduced the quantity of exposed surface Pt atoms due to strong coordination effect. The presence of SO42− group significantly promoted the propane combustion reaction but inhibited the methane combustion reaction. It can be inferred that the promotion on propane combustion is ascribed to the enhanced activation of C–C bond (370.3 kJ mol−1) by sulfates. Whereas the sulfates are not favorable for the activation and cracking of C-H bond (439.3 kJ mol−1), and the reduced number of exposed Pt sites results in the activity decrease of methane combustion. [ABSTRACT FROM AUTHOR]

MoO3 promoted Pt/ZrO2 catalysts were prepared by co-impregnation (Pt–Mo/ZrO2) or stepwise impregnation (Pt/Mo/ZrO2 and Mo/Pt/ZrO2) for propane combustion. The impregnation order affects the density of active Pt–MoO3 interfacial sites, in the order of: Pt–Mo/ZrO2 (7.60 μmol gcat−1) > Pt/Mo/ZrO2 (3.40 μmol gcat−1) > Mo/Pt/ZrO2 (1.20 μmol gcat−1). The turnover frequency, TOFPt–MoO3, of Pt–MoO3 interfacial sites is much higher than the TOFPt of Pt active sites (at least 50 folds). Thus, the catalytic activity for propane combustion is in the order of: Pt–Mo/ZrO2 > Pt/Mo/ZrO2 > Mo/Pt/ZrO2 > Pt/ZrO2. Kinetic results illustrate that the MoO3 promotion significantly weakens the strong adsorption of oxygen species on the catalyst and enhances the catalytic activity. The activation energy is reduced the most over the Pt–Mo/ZrO2 catalyst (Ea of the Pt/ZrO2 catalyst: 102.8 ± 4.8 kJ mol−1; Ea of the Pt–Mo/ZrO2 catalyst: only 40.3 ± 1.8 kJ mol−1). [ABSTRACT FROM AUTHOR]

External apical root resorption is among the most common risks of orthodontic treatment, and it cannot be completely avoided and predicted. Risk factors causing orthodontic root resorption can generally be divided into patient- and treatment-related factors. Root resorption that occurs during orthodontic treatment is usually detected by radiographical examination. Mild or moderate root absorption usually does no obvious harm, but close attention is required. When severe root resorption occurs, it is generally recommended to suspend the treatment for 3 months for the cementum to be restored. To unify the risk factors of orthodontic root resorption and its clinical suggestions, we summarized the theoretical knowledge and clinical experience of more than 20 authoritative experts in orthodontics and related fields in China. After discussion and summarization, this consensus was made to provide reference for orthodontic clinical practice.

Background: Peri-miniscrew implant is a temporary assistant armamentarium for the treatment of severe malocclusion and complex tooth movement, the inflammation around it is the main reason for the failure of orthodontic treatment due to the implant loosening and falling out. Inflammation around the peri-miniscrew implant is associated with the release of pro-inflammatory cytokines. These pro-inflammatory cytokines, in turn, recruit immune cells (such as macrophages, dendritic cells, T cells, and B cells), which can produce and release inflammatory biomarkers, regulate the interaction between immune cells, periodontal ligament cells, osteoblasts, and so on. However, there is currently no effective clinical treatment plan to prevent inflammation around implants., Purpose: To investigate the potentially essential factors in the inflammatory response around the peri-miniscrew implant and explore the signaling pathways involved., Methods: Here, we review the studies focused on inflammatory biomarkers (Interleukins, tumor necrosis factor-α (TNF-α), receptor activator of NF-κB ligand (RANKL), matrix metalloproteinases (MMPs), and cellular adhesion molecules (CAMs)) in peri-miniscrew implant crevicular fluid (PMICF), as well as inflammatory signaling pathways (Wnt5a, JNK, Erk1/2, NF-κBp65 and TAB/TAK) in periodontal cells from 1998 to 2020., Results: A literature search revealed TLR-2, TLR-4, LOX-1, and BMPs are involved in regulating ILs (IL-1β, IL-6, IL-8, and IL-17), TNF-α, RANKL, MMP-2, MMP-9 expression via JNK, Erk1/2, Wnt5a, NF-κBp65, OPN, and TAB/TAK signaling pathways. Among them, IL-1β and IL-6 are the critical inflammation factors in the signaling pathways inducing the inflammatory reaction surrounding implants. Besides, CAM-1 was also regulated by MMP-9 and IL-17., Conclusion: There are considerable potential factors involving regulating inflammatory biomarkers on downstream signaling pathways in peri-minisrew implant crevicular fluid., Clinical Significance: This review provides the substantiation of these cell factors and signaling pathways around peri-miniscrew implants, proposes more practical clinical therapeutic ideas and schemes for improving the stability and clinical efficacy of peri-miniscrew implants.

Objective: To investigate the regulatory effect of central synaptic plasticity on pain induced by experimental tooth movement and to analyzethe expression of protein kinases Mζ (PKMζ) in the anterior cingulate cortex (ACC) after applying different magnitude of orthodontic force., Methods: One hundred and thirty-six male Sprague-Dawley (SD) rats (200-250 g) were used in this study. Orthodontic tooth movement devices were placed on the teeth in the experimental group, and different orthodontic forces (0.39, 0.78, 1.17 N) were applied to move the maxillary first molars, respectively. The same mechanical devices were placed on the teeth in sham-treated group and no orthodontic force was applied. No orthodontic procedure was applied in blank control group. The average time spent on mouth- wiping behavior in each group was recorded after experimental tooth movement. Brain tissue of the anterior cingulate cortex was isolated on day 3 after experiment, and the expression level of PKMζ was analyzed with the method of immunohistochemistry and enzyme-linked immune sorbent assay. ζ-pseudosubstrate inhibitory peptide (ZIP), a selective inhibitor for PKMζ, was injected into ACC on day 3 after experimental tooth movement, and the effects of ZIP on mouth-wiping behavior were evaluated., Results: No statistical difference was found between the blank control group and the sham- treated group in the average time spent on mouth-wiping, value of A and expression level of PKMζ (P > 0.05). Compared with the sham-treated group and blank control group, the average time of mouth-wiping behavior [(58.6±6.9), (66.3±7.8), (78.9±8.7) s], value of A (4 569±454, 6 850±365, 8 294±558) and expression level of PKMζ [(0.32±0.02), (0.34±0.02), (0.36±0.02) mg/L] in 0.39, 0.78, 1.17 N force group were found to be up-regulated with the increase of orthodontic force (P < 0.05). LSD test in three experimental sub-group showed statistical difference (P < 0.05). After microinjection of ZIP, the average time spent on mouth-wiping behavior significantly decreased (P < 0.01), while microinjecting saline did not change rats' mouth-wiping behavior (P > 0.05)., Conclusions: More pain caused by increased orthodontic force maybe due to the up-regulation of PKMζ in the anterior cingulate cortex.

Objective: To investigate the development of third molar embryo and establish the normal value of posterior arch length of adolescence in Chengdu., Methods: The samples consisted of 40 males and 41 females with Class 1 dentitions, normal second molar occlusion, no history of orthodontic treatment, and good facial balance. Cephalometry and statistic analysis were conducted for all the subject., Results: The normal value of posterior arch length of maxilla in male was(16.52 +/- 2.35) mm and in female was(16.42 +/- 2.55) mm. The normal length of mandible was(13.00 +/- 2.44) mm in male and(12.43 +/- 2.18) mm in female. But statistic analysis showed no gender difference. Most of the third molar embryo had been formed and their tooth crowns had been calcified, the occurrence ratio was 84.0% in maxilla and 85.2% in mandible. Most of them located in the middle and inclined mesially., Conclusion: The data obtained in this study will be valuable for our clinical practice and be helpful for the study concerning dento-facial growth and development.