3-dimensional analysis of hard- and soft-tissue symmetry in a Chinese population.

BACKGROUND: Facial symmetry severely affects appearance and function. Large numbers of patients seek orthodontic treatment to improve facial symmetry. However, the correlation between hard- and soft-tissue symmetry is still unclear. Our aim was to investigate the hard- and soft-tissue symmetry in subjects with different levels of menton deviation and sagittal skeletal classes with 3D digital analysis and to investigate the relationship between the entire and individual hard- and soft-tissues. METHODS: A total of 270 adults (135 males and 135 females) consisting of 45 subjects of each sex in each sagittal skeletal classification group. All subjects were further classified into relative symmetry (RS), moderate asymmetry (MA) and severe asymmetry (SA) groups based on the degree of menton deviation from the mid-sagittal plane (MSP). The 3D images were segmented into anatomical structures and mirrored across the MSP after establishing a coordinate system. Original and mirrored images were registered by a best-fit algorithm, and the corresponding root mean square (RMS) values and colormap were obtained. The Mann‒Whitney U test and Spearman correlation were conducted for statistical analysis. RESULTS: The RMS increased with greater deviations with regard to the deviation of the menton in most of anatomical structures. Asymmetry was represented in the same way regardless of sagittal skeletal pattern. The soft-tissue asymmetry had a significant correlation with dentition in the RS group (0.409), while in the SA group, it was related to the ramus (0.526) and corpus (0.417) in males and was related to the ramus in the MA (0.332) and SA (0.359) groups in females. CONCLUSIONS: The mirroring method combining CBCT and 3dMD provides a new approach for symmetry analysis. Asymmetry might not be influenced by sagittal skeletal patterns. Soft-tissue asymmetry might be reduced by improving the dentition in individuals with RS group, while among those with MA or SA, whose menton deviation was larger than 2 mm, orthognathic treatment should be considered.

Efficiency evaluation of maxillary molar distalization using Invisalign based on palatal rugae registration.

INTRODUCTION: This study aimed to compare the predicted maxillary molar distalization with the achieved clinical outcome using the palatal rugae area for registration and superimposition of digital models. Understanding Invisalign efficiency may assist clinicians in predicting changes, thus applying specific measures to minimize the chance of midcourse correction later. METHODS: The study sample included 38 patients with a mean age of 25.4 years, eligible for Invisalign treatment and requiring distalization of maxillary molars. Two digital models were acquired using iTero intraoral scanner (Align Technology, Santa Clara, Calif) before treatment and after maxillary first and second molar distalization. The 2 digital models were superimposed using the palatal rugae area for registration. The predicted tooth movement compared to the achieved values. One hundred forty-two maxillary molars (71 first molar and 71 second molar) were measured for distal movement, and 228 maxillary anterior teeth were evaluated for anterior anchorage loss. RESULTS: The predicted distal movement of the maxillary first molar (P <0.0001) and maxillary second molar (P <0.0001) differed significantly from the actual values. There was a statistically significant correlation between the amount of distal molar movement and the amount of anchorage loss (r = 0.3900, P <0.008) for the central incisor, and (r = 0.3595, P <0.013) for the lateral incisor. CONCLUSIONS: Invisalign can be used successfully for adult patients requiring maxillary molar distalization when a mean distalization movement of 2.6 mm was prescribed. Clinicians should be aware of the countereffect if maxillary molars are planned to move distally, especially if the patient presented initially with a large overjet, so the need to prescribe overcorrection or the use of auxiliaries can be addressed earlier.

An Automated Method of 3D Facial Soft Tissue Landmark Prediction Based on Object Detection and Deep Learning.

BACKGROUND: Three-dimensional facial soft tissue landmark prediction is an important tool in dentistry, for which several methods have been developed in recent years, including a deep learning algorithm which relies on converting 3D models into 2D maps, which results in the loss of information and precision. METHODS: This study proposes a neural network architecture capable of directly predicting landmarks from a 3D facial soft tissue model. Firstly, the range of each organ is obtained by an object detection network. Secondly, the prediction networks obtain landmarks from the 3D models of different organs. RESULTS: The mean error of this method in local experiments is 2.62±2.39, which is lower than that in other machine learning algorithms or geometric information algorithms. Additionally, over 72% of the mean error of test data falls within ±2.5 mm, and 100% falls within 3 mm. Moreover, this method can predict 32 landmarks, which is higher than any other machine learning-based algorithm. CONCLUSIONS: According to the results, the proposed method can precisely predict a large number of 3D facial soft tissue landmarks, which gives the feasibility of directly using 3D models for prediction.

Can canines alone be used for age estimation in Chinese individuals when applying the Kvaal method?

Due to the secondary dentin formation, the dental pulp undergoes changes in shape throughout life. Based on this phenomenon, the Kvaal method has been applied to various populations for age estimation, and its usefulness has been verified. When applying the Kvaal method to Chinese subjects, we observed a relatively strong correlation between mandibular canines and age. This study notes the correlation between canines and chronological age and is the first to identify which canine is most closely related to chronological age. In addition, a new, simpler formula is determined based on canines according to Kvaal's methodology. The radiographs of 360 individuals from northern China were selected, from which the widths and lengths of the pulp from four canines were measured according to the Kvaal method. Next, inter- and intra-observer reliabilities were analyzed in order to assess the repeatability of these measurements. The correlation between measurements and age was examined, and Chinese-specific age estimation formulae were derived. The results revealed that the ratios from the left maxillary canine exhibited the strongest correlation with age compared to the other canines, whereas the left mandibular canine showed the weakest correlation, which may contribute to the overall poor correlation of mandibular canines with age. What's more, the formula derived from the left maxillary canine in this study displayed the highest coefficients of determination, and the formula derived from all canines showed the lowest residuals. Both of these formulae performed better than the Chinese-specific formula derived from six different types of teeth in our previous study, which had formerly possessed the highest coefficients of determination and the lowest residuals. Thus, we concluded that canines do play an important role in age estimation in the Chinese population, and the correlation between maxillary canines and chronological age is stronger than that of mandibular canines, although no distinct trend as to which side is better correlated with age was established. Going forward, we recommend the analysis of additional samples from different geographical regions and populations to further verify the importance of canines in age estimation.

Evaluation of the stability of the palatal rugae using the three-dimensional superimposition technique following orthodontic treatment.

OBJECTIVES: To determine the uniqueness and stability of the palatal rugae after orthodontic treatment. METHODS: Cast models of untreated subjects (n = 50) were obtained twice at intervals of 8-30 months. Cast models of patients who received non-extraction (n = 50) and extraction (n = 50) orthodontic treatment were obtained before and after treatment at intervals of 11-41 months and 14-49 months, respectively. All 300 cast models were scanned digitally. The palatal rugae were manually extracted and transformed into 3D point clouds using reverse engineering software. An iterative closest point (ICP) registration algorithm based on correntropy was applied, and the minimum point-to-point root mean square (RMS) distances were calculated to analyze the deviation of palatal rugae for scans of the same subject (intrasubject deviation [ISD]) and between different subjects (between-subject deviation [BSD]). Differences in ISD between each group and the deviation between ISD and BSD of all 150 subjects were evaluated. RESULTS: Significant differences were found in the 150 ISD and 1225 BSD in each group, as well as the 150 ISD and 11,175 BSD across all groups. The mean values of ISD in untreated, non-extraction and extraction group were 0.178, 0.229 and 0.333 mm, respectively. When the first ruga was excluded in the extraction group, the mean ISD decreased to 0.241 mm, which was not significantly different from that in the non-extraction group (p = 0.314). CONCLUSIONS: Orthodontic treatment can influence the palatal rugae, especially in cases of extraction. Furthermore, variation mainly existed in the first ruga in cases of extraction. However, palatal rugae are still unique and may be used as a supplementary tool for individual identification. CLINICAL SIGNIFICANCE: This study indicates that palatal rugae might be applied in the evaluation of orthodontic tooth movement and forensic individual identification. The registration algorithm based on correntropy provides a reliable, precise, and convenient method for palatal rugae superimposition.

Gas-Sensitive Cellulosic Triboelectric Materials for Self-Powered Ammonia Sensing.

Gas-sensitive materials are capable of dynamic identification and content monitoring of specific gases in the environment, and their applications in the field of gas sensing are promising. However, weak adsorption properties are the main challenge limiting the application of gas-sensitive materials. A highly adsorbent gas-sensitive cellulose nanofibril (CNF)-based triboelectric material with a layered structure is prepared here and it is applied to self-powered gas sensing. The layered structure of the triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane cellulose nanofiber (PFOTES-CNF)-based gas-sensitive material further enhances the adsorption of the material due to electrostatic adsorption in the electrostatic field induced by triboelectricity. It is found that the ammonia-sensitive material obtained by loading Ti3 C2 Tx in PFOTES-CNF has a fast response/recovery (12/14 s), high sensitivity response (Vair /Vgas  = 2.1), high selectivity response (37.6%), and low detection limit (10 ppm) for 100 ppm of ammonia gas. In addition, the ammonia-sensitive CNF-based triboelectric material can accurately identify NH3 concentration changes in the range of 10-120 ppm and transmit the signal wirelessly to the user interface, facilitating real-time online monitoring of NH3 in the environment. A novel strategy is provided here for designing and preparing high-performance gas-sensitive composites and the analysis of self-powered gas sensing is guided.

Hierarchical Porous Cellulosic Triboelectric Materials for Extreme Environmental Conditions.

Synthetic polymer materials such as paraformaldehyde and polyamides are widely used in the field of energy engineering. However, they pose a challenge to environmental sustainability because they are derived from petrochemicals that are non-renewable and difficult to degrade in the natural environment. The development of high-performance natural alternatives is clearly emerging as a promising mitigation option. Inspired by natural bamboo, this research reports a "three-step" strategy for the large-scale production of triboelectric materials with special nanostructures from natural bamboo. Benefiting from the special hierarchical porous structure of the material, Bamboo/polyaniline triboelectric materials can reach short-circuit current of 2.9 µA and output power of 1.1 W m-2 at a working area of only 1 cm2 , which exceeds most wood fiber-based triboelectric materials. More importantly, it maintains 85% energy harvesting after an extreme environment of high temperature (200 °C), low temperature (-196 °C), combustion environment, and multiple thermal shocks (ΔT = 396 °C). This is unmatched by current synthetic polymer materials. This work provides new research ideas for the construction and application of biomass structural materials under extreme environmental conditions.

Three-dimensional superimposition of digital models for individual identification.

Dentition is an individualizing structure in humans that may be potentially utilized in individual identification. However, research on the use of three-dimensional (3D) digital models for personal identification is rare. This study aimed to develop a method for individual identification based on a 3D image registration algorithm and assess its feasibility in practice. Twenty-eight college students were recruited; for each subject, a dental cast and an intraoral scan were taken at different time points, and digital models were acquired. The digital models of the dental casts and intraoral scans were assumed as antemortem and postmortem dentition, respectively. Additional 72 dental casts were extracted from a hospital database as a suspect pool together with 28 antemortem models. The dentition images of all of the models were extracted. Correntropy was introduced into the traditional iterative closest point algorithm to compare each postmortem 3D dentition with 3D dentitions in the suspect pool. Point-to-point root mean square (RMS) distances were calculated, and then 28 matches and 2772 mismatches were obtained. Statistical analysis was performed using the Mann-Whitney U test, which showed significant differences in RMS between matches (0.18±0.03mm) and mismatches (1.04±0.67mm) (P<0.05). All of the RMS values of the matched models were below 0.27mm. The percentage of accurate identification reached 100% in the present study. These results indicate that this method for individual identification based on 3D superimposition of digital models is effective in personal identification.

Melatonin protect the development of preimplantation mouse embryos from sodium fluoride-induced oxidative injury.

Recently study shows that melatonin can protect embryos from the culture environment oxidative stress. However, the protective effect of melatonin on the mouse development of preimplantation embryos under sodium fluoride (NaF) induced oxidative stress is still unclear. Here, we showed that exposure to NaF significantly increased the reactive oxygen species (ROS) level, decreased the blastocyst formation rates, and increased the fragmentation, apoptosis and retardation of blastocysts in the development of mouse preimplantation embryos. However, the protective of melatonin remarkable increased the of blastocyst formation rates, maintained mitochondrial function and total antioxidant capacity by clearing ROS. Importantly the data showed that melatonin improved the activity of enzymatic antioxidants, including glutathione(GSH), superoxide dismutase(SOD), and malonaldehyde (MDA), and increased the expression levels of antioxidative genes. Taken together, our results indicate that melatonin prevent NaF-induced oxidative damage to mouse preimplantation embryo through down regulation of ROS level, stabilization of mitochondrial function and modulation of the activity of antioxidases and antioxidant genes.

Melatonin-mediated upregulation of Sirt3 attenuates sodium fluoride-induced hepatotoxicity by activating the MT1-PI3K/AKT-PGC-1α signaling pathway.

Mitochondrial reactive oxygen species (ROS) production has been implicated in the pathogenesis of fluoride toxicity in liver. Melatonin, an indolamine synthesized in the pineal gland, was previously shown to protect against sodium fluoride (NaF)-induced hepatotoxicity. This study investigated the protective effects of melatonin pretreatment on NaF-induced hepatotoxicity and elucidates the potential mechanism of melatonin-mediated protection. Reducing mitochondrial ROS by melatonin substantially attenuated NaF-induced NADPH oxidase 4 (Nox4) upregulation and cytotoxicity in L-02 cells. Melatonin exerted its hepatoprotective effects by upregulating Sirtuin 3 (Sirt3) expression level and its activity. Melatonin increased the activity of manganese superoxide dismutase (SOD2) by promoting Sirt3-mediated deacetylation and promoted SOD2 expression through Sirt3-regulated DNA-binding activity of forkhead box O3 (FoxO3a), thus inhibiting the production of mitochondrial ROS induced by NaF. Notably, increased peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α) by melatonin activated the Sirt3 expression, which was regulated by an estrogen-related receptor (ERR) binding element (ERRE) mapped to Sirt3 promoter region. Analysis of the cell signaling pathway profiling systems and specific pathway inhibition indicated that melatonin enhances PGC-1α expression by activating the PI3K/AKT signaling pathway. Importantly, inhibition of melatonin receptor (MT)-1 blocked the melatonin-activated PI3K/AKT-PGC-1α-Sirt3 signaling. Mechanistic study revealed that the protective effects of melatonin were associated with down-regulation of JNK1/2 phosphorylation. Our findings provided a theoretical basis that melatonin mitigated NaF-induced hepatotoxicity, which, in part, was mediated through the activation of the Sirt3 pathway.