Accuracy of a calibration method based on cone beam computed tomography and intraoral scanner data registration for robot-assisted implant placement: An in vitro study.

STATEMENT OF PROBLEM: Robotic systems have shown promise for implant placement because of their accuracy in identifying surgical positions. However, research on the accuracy of patient calibration methods based on cone beam computed tomography (CBCT) and intraoral scanner (IOS) data registration is lacking. PURPOSE: The purpose of this in vitro study was to develop a calibration method based on the registration of CBCT and IOS data of a robot-assisted system for implant placement, evaluate the accuracy of this calibration method, and explore the accuracy of robot-assisted surgery at different implant positions. MATERIAL AND METHODS: Twenty standardized, polyurethane, partially edentulous maxillary typodonts were divided into 2 groups: one group used a calibration method based solely on CBCT data (CBCT group), and the other used a calibration method based on the registration of CBCT and IOS data (IOS group). Four implants were planned for each typodont in the right second premolar, left central incisor, left first premolar, and left second molar positions. The robot performed the osteotomies and implant placement step by step according to the preoperative plan. The operating software program automatically measured the deviation between the planned and actual implant position. Two-way analysis of variance (ANOVA) and the least significant difference (LSD) post hoc test (α=.05) were used to analyze differences between the test groups. RESULTS: The angular deviation and 3-dimensional deviations at implant platform and apex between the 2 calibration methods did not significantly differ among the 4 implant positions (P>.05). The horizontal and depth deviations at the implant platform and apex levels between the 2 calibration methods did not significantly differ among the 4 implant positions (P>.05). In the anterior region (left central incisor), the CBCT group showed higher horizontal deviation at both the implant platform and apex compared with the IOS group (P<.05). Conversely, the IOS group had greater depth deviation at both the implant platform and apex than the CBCT group (P<.05). In the posterior region, with or without distal extension (right second premolar, left first premolar, and left second molar), no statistically significant differences were found between the 2 calibration methods (P>.05). CONCLUSIONS: The calibration method that was based on the registration of CBCT and IOS data demonstrated high accuracy. No significant differences in the accuracy of the calibration methods for robot-assisted implant placement were found between the CBCT group and IOS group.

Development and accuracy assessment of a crown lengthening surgery robot for use in the esthetic zone: An in vitro study.

STATEMENT OF PROBLEM: Crown lengthening surgery has been widely used to enhance the health and esthetics of anterior teeth, and its accuracy significantly influences surgical outcomes. However, the feasibility and accuracy of a robot system for crown lengthening surgery remains unknown. PURPOSE: The purpose of this in vitro study was to develop a crown lengthening surgery robot and evaluate its accuracy. MATERIAL AND METHODS: A robotic crown lengthening surgery system consisting of a robotic arm, a robotic software system, and an optical tracking device was designed. Intraoral scanning and cone beam computed tomography (CBCT) were performed on 18 artificial dentition models. The data were imported into the planning software program to synthesize a surgical path for gingivectomy and alveolectomy. Subsequently, a robotic arm equipped with a high-speed handpiece was used to perform these surgical procedures. Postoperatively, the models were rescanned for evaluation, with the accuracy (trueness ±precision) of the surgical outcomes of gingivectomy and alveolectomy being assessed from the trajectories in the highest, lowest, and overall regions. Differences between groups were analyzed by using the independent sample t test and the Levene test (α=.05). RESULTS: Crown lengthening surgery was feasible in vitro using the robot developed in this study. The overall robot-assisted crown lengthening surgery accuracy (trueness ±precision) of gingivectomy (0.23 ±0.08 mm) was significantly higher than that of alveolectomy (0.33 ±0.11 mm) (P<.05). CONCLUSIONS: Robot-assisted crown lengthening surgery had acceptable accuracy generally and can be considered a feasible treatment option.

Enhancement of Biocompatibility of High-Transparency Zirconia Abutments with Human Gingival Fibroblasts via Cold Atmospheric Plasma Treatment: An In Vitro Study.

The objective of this study was to explore the effects of cold atmospheric plasma (CAP) treatment on the biological behavior of human gingival fibroblasts (HGFs) cultured on the surface of high-transparency zirconia. Two types of zirconia, 3Y-ZTP and 4Y-PSZ, were subjected to a CAP treatment for various treatment durations. Analyses of the physical and chemical properties of 3Y-ZTP and 4Y-PSZ were conducted using scanning electron microscopy, contact angle measurements, and X-ray photoelectron spectroscopy, both before and after CAP treatment. The biological responses of HGFs on both surfaces were assessed using CCK-8 assay, confocal laser scanning microscopy, and real-time PCR. Initially, the oxygen and hydroxyl contents on the surface of 4Y-PSZ exceeded those on 3Y-ZTP. CAP treatment enhanced the surface hydrophilicity and the reactive oxygen species (ROS) content of 4Y-PSZ, while not altering the surface morphology. After CAP treatment, HGFs' adhesion on 4Y-PSZ was superior, with more pronounced effects compared to 3Y-ZTP. Notably, HGFs counts and the expression of adhesion-related genes on 4Y-PSZ peaked following the CAP exposures for 30 s and 60 s. Consequently, this study demonstrates that, following identical CAP treatments, 4Y-PSZ is more effective in promoting HGFs adhesion compared to traditional 3Y-ZTP zirconia.

Optical properties of monolithic zirconia fabricated with nanoparticle jetting.

STATEMENT OF PROBLEM: Excellent optical properties are essential for esthetic dental materials. However, the translucency and color masking ability of zirconia fabricated with nanoparticle jetting (NPJ), a type of printed zirconia, are unknown. PURPOSE: The purpose of this in vitro study was to evaluate the translucency and color masking ability of zirconia fabricated using NPJ. MATERIAL AND METHODS: A total of 90 specimens with thicknesses of 1.5, 1.0, and 0.5 mm were fabricated using high translucent milled zirconia (HT), low translucent milled zirconia (LT), and NPJ. CIELab values (L*, a*, and b*) of the specimens over 7 backgrounds, black, white, VitaB1, VitaA2, VitaA4, gold alloy (Au), and titanium (Ti), were obtained using a spectral radiometer. The relative translucency parameter (RTP) and color difference (∆E) of specimens over VitaB1, VitaA4, Au, and Ti were determined using VitaA2 as the control with the CIEDE2000 color difference equation. The normality of the data distribution was determined using the Shapiro-Wilk test. Differences among groups were analyzed using 2-way analysis of variance and the Student-Newman-Keuls (SNK) post hoc test (α=.05). The ∆E of specimens was analyzed according to perceptibility (∆E=0.8) and acceptability (∆E=1.8) thresholds using the 1 sample t test. The correlation between RTP and ∆E and RTP/∆E and thickness was examined using the Pearson correlation analysis. RESULTS: Statistically significant differences were observed in translucency and color masking ability among HT, LT, and NPJ (P<.05). The RTP value was the lowest for zirconia fabricated with NPJ (P<.001) and highest for HT (P<.001). Monolithic zirconia fabricated with NPJ had lower ∆E values than those of HT and LT for the same thickness and background (P<.05). A positive correlation was found in RTP and ∆E (P<.001). A negative correlation was observed in RTP and thickness (P<.001) and ∆E and thickness across a constant background (P<.001). CONCLUSIONS: Zirconia fabricated with NPJ was less translucent and had a greater color masking ability for discolored backgrounds than HT and LT.

CAD-CAM pressure-exerting device to create an ovate pontic for an implant-supported fixed partial denture.

This article presents a digital approach to fabricating a computer-aided design and computer-aided manufacturing (CAD-CAM) ovate pontic creating device for an implant-supported fixed partial denture. Intraoral digital scanning was done after osseointegration, and the pontic was designed as 2 separate parts, with the fixed part connecting the coronal part of the restoration and an ovate former shaping the pontic area. A mechanical spring was placed between the 2 parts to exert consistent pressure on the ovate former. An ovate pontic can be individually created rapidly and precisely as designed with this novel CAD-CAM device. This technology can be used to personalize the gingival morphology, improve esthetics, and minimize discomfort during the procedure.

[Effect of different cleaning methods on bond strength and surface wettability of high translucency zirconia].

PURPOSE: To study the effect of different cleaning methods on the shear bond strength of self-adhesive resin cement to saliva-contaminated high translucency zirconia and surface wettability. METHODS: Eighty zirconia specimens were randomly divided into 5 groups (n=16), i.e., control group(not contaminated), 75% ethanol group,cleaning paste group,airborne-particle abrasion group, and atmospheric pressure cold plasma group. The contact angles was measured, shear bond strength were examined, and fracture types were determined. SPSS 26.0 software package was used for statistical analysis of the data. RESULTS: The atmospheric pressure cold plasma group produced the lowest contact angle(P＜0.05). The shear bond strength of the airborne-particle abrasion group, the cleaning paste group and the atmospheric pressure cold plasma group respectively were similar to the control group without significant difference(P＞0.05), while those were significantly higher than 75% ethanol group(P＜0.05). The mixed fracture mode of the atmospheric pressure cold plasma group evidently increased. CONCLUSIONS: Airborne-particle abrasion, cleaning paste and atmospheric pressure cold plasma overcome the effects of saliva contamination, producing the shear bond strength to zirconia similar to the control group. The atmospheric pressure cold plasma improves hydrophilicity of high translucency zirconia significantly.

Accuracy of three types of digital guides for crown lengthening surgery: An in vitro study.

Background/purpose: The guided protocols always yield a higher accuracy than freehand surgery. However, the accuracy of digital guides for crown lengthening surgery (CLS) is unknown. The purpose of this study was to evaluate the trueness of 3 types of digital guides for CLS. Materials and methods: Twenty individually designed maxillary models were divided into 4 groups according to surgical guides: type I (T1), type II (T2), type III (T3), and free-hand. T1 comprised a planed gingival margin at the tissue level. T2 included both the planed gingival margin and alveolar crest at the tissue level. T3 consisted of a planed gingival margin at the tissue level and an alveolar crest at the bone level. CLS was performed under the indication of the guides. Trueness of the guides was evaluated through the deviation of the gingival zenith and alveolar crest height. Results: The control group had higher vertical and horizontal distance deviations of gingival zenith compared to the 3 digital guide groups (P < 0.001). There were no significant differences among the 3 test groups in terms of gingival zenith deviations (P > 0.05). With regard to height deviation of alveolar crest, the control and T1 groups were higher than T2 group (P < 0.001), while T3 group had the lowest deviations among the 4 groups (P < 0.001). Conclusion: The digital guides assisted CLS procedures are more accurate than free-hand method. The trueness of type III guide was better than type I and type II.

Rapid weather changes are associated with daily hospital visitors for atrial fibrillation accompanied by abnormal ECG repolarization: a case-crossover study.

BACKGROUND: Atrial fibrillation (AF) is highly prevalent in the population, yet the factors contributing to AF events in susceptible individuals remain partially understood. The potential relationship between meteorological factors and AF, particularly with abnormal electrocardiograph (ECG) repolarization, has not been adequately studied. This case-crossover study aims to investigate the association between meteorological factors and daily hospital visits for AF with abnormal ECG repolarization in Shanghai, China. METHODS: The study cohort comprised 10,325 patients with ECG-confirmed AF who sought treatment at Shanghai Sixth People's Hospital between 2015 and 2018. Meteorological and air pollutant concentration data were matched with the patient records. Using a case-crossover design, we analyzed the association between meteorological factors and the daily count of hospital visitors for AF with abnormal ECG repolarization at our AF center. Lag analysis models were applied to examine the temporal relationship between meteorological factors and AF events. RESULTS: The analysis revealed statistically significant associations between AF occurrence and specific meteorological factors. AF events were significantly associated with average atmospheric pressure (lag 0 day, OR 0.9901, 95% CI 0.9825-0.9977, P < 0.05), average temperature (lag 1 day, OR 0.9890, 95% CI 0.9789-0.9992, P < 0.05), daily pressure range (lag 7 days, OR 1.0195, 95% CI 1.0079-1.0312, P < 0.01), and daily temperature range (lag 5 days, OR 1.0208, 95% CI 1.0087-1.0331, P < 0.01). Moreover, a significant correlation was observed between daily pressure range and daily temperature range with AF patients, particularly those with abnormal ECG repolarization, as evident in the case-crossover analysis. CONCLUSION: This study highlights a significant correlation between meteorological factors and daily hospital visits for AF accompanied by abnormal ECG repolarization in Shanghai, China. In addition, AF patients with abnormal ECG repolarization were found to be more vulnerable to rapid daily changes in pressure and temperature compared to AF patients without such repolarization abnormalities.

Trueness of 4 sectional-cast digital methods for transferring the interocclusal relationship in complete mouth rehabilitation.

STATEMENT OF PROBLEM: An accurate digital workflow for transferring the interocclusal relationship from complete arch diagnostic interim restorations to complete arch tooth preparations is essential in complete mouth rehabilitation. However, research on the accuracy of digital cross-mounting methods is lacking. PURPOSE: The purpose of this in vitro study was to compare the trueness of 4 sectional-cast digital cross-mounting methods in transferring the interocclusal relationship for complete mouth rehabilitation. MATERIAL AND METHODS: Maxillary and mandibular anatomic typodonts were used to build complete arch tooth preparations and diagnostic interim restorations for complete mouth rehabilitation in vitro. Four sectional casts were designed: an anterior cast (AR), a posterior cast (PO), a unilateral cast (UL), and a tripod cast (TR). Both extraoral scanning (EOS) and intraoral scanning (IOS) were used to obtain intermediate digital sectional casts, which were cross-registered with diagnostic interim restorations and definitive casts to transfer the interocclusal relationship. Trueness was determined by assessing tooth distance deviation and mandibular 3-dimensional (3D) deviation. Differences among the 4 sectional-cast methods were analyzed with the Kruskal-Wallis test, and differences between the 2 scanning methods were analyzed with the Mann-Whitney U test (α=.05). RESULTS: Significant differences in the trueness of interocclusal relationship transfer were observed among the 4 sectional-cast methods (P<.05). Regarding tooth overall distance deviation, TR-EOS found no statistically significant difference compared with PO-EOS (P>.05), but TR-EOS had half the overall distance deviation of PO-EOS. Both TR-EOS and PO-EOS had smaller deviations than the AR-EOS and UL-EOS groups (P<.05). TR-IOS had a smaller distance deviation than the AR-IOS, PO-IOS, and UL-IOS groups (P<.05). The overall distance deviation of EOS was significantly smaller than that of IOS in the TR and PO groups (P<.05). Regarding mandibular 3D deviation, TR-EOS found no statistically significant difference but had half the root mean square (RMS) of 3D deviation compared with the PO-EOS groups (P>.05). Both TR-EOS and PO-EOS groups had a smaller RMS than the AR-EOS and groups (P<.05). The TR-IOS group had a smaller RMS than the AR-IOS, PO-IOS, and UL-IOS groups (P<.05). The 3D deviation of EOS was significantly smaller than that of IOS in the PO group (P<.05). CONCLUSIONS: Both EOS and IOS with the tripod sectional-cast digital method accurately transferred the interocclusal relationship for complete mouth rehabilitation.

Effect of build angle on the dimensional accuracy of monolithic zirconia crowns fabricated with the nanoparticle jetting technique.

STATEMENT OF PROBLEM: The build angle is an essential parameter in additive manufacturing. Its effect on the dimensional accuracy of zirconia restorations fabricated using the nanoparticle jetting (NPJ) technique is unknown. PURPOSE: The purpose of this in vitro study was to evaluate the effect of the build angle on the dimensional accuracy of monolithic zirconia complete crowns fabricated by using NPJ. MATERIAL AND METHODS: Standardized artificial right maxillary incisors and mandibular first molars were prepared for ceramic complete crowns. In total, 100 monolithic zirconia crowns were fabricated using NPJ at build angles of 0, 45, 90, 135, and 180 degrees (n=10/angle for incisors and molars). The dimensional accuracies in the external, marginal, and intaglio regions were determined by superimposing the scanned data and computer-aided design data on the crowns. Root mean square (RMS) values were used to analyze the accuracy of the zirconia crowns overall and at the external, marginal, and intaglio surfaces. The Shapiro-Wilk test was used to examine the normality of data distribution. Differences among test groups were assessed using a 1-way analysis of variance and the post hoc least significant difference test (α=.05). RESULTS: Significant differences were found in the accuracy of monolithic zirconia incisor and molar complete crowns in the external, marginal, and intaglio regions among the 5 build angles (P<.05). For incisors, the external RMS value was lowest for a build angle of 45 degrees (18.2 ±3.0 µm), the marginal and intaglio RMS values were lowest for a build angle of 135 degrees (47.4 ±10.7 and 26.5 ±6.1 µm, respectively), and the overall RMS values did not differ significantly among the 5 build angles (P>.05). For molars, build angles of 0 degrees and 180 degrees yielded the lowest RMS values overall (22.3 ±1.5 and 21.8 ±3.2 µm, respectively) and in the external (23.2 ±2.9 and 22.3 ±2.5 µm, respectively) and intaglio (22.2 ±3.7 and 21.2 ±4.6 µm, respectively) regions. No significant difference was observed in the marginal area among the 5 build angles (P>.05). The overall RMS values reflecting dimensional accuracy for the 5 build angles were between 23.5 and 26.7 µm for incisors and 21.8 and 26.2 µm for molars. CONCLUSIONS: The dimensional accuracy of monolithic zirconia crowns fabricated by using NPJ was affected by the build angle and was within clinically acceptable limits.

The association between air pollution and the daily hospital visits for atrial fibrillation recorded by ECG: a cross-sectional study.

BACKGROUND: The relationship between air pollution and atrial fibrillation (AF) recorded by electrocardiograph (ECG) has not yet been illustrated which worsens AF precaution and treatment. This research evaluated the association between air pollution and daily hospital visits for AF with ECG records. METHODS: The study enrolled 4933 male and 5392 female patients whose ECG reports indicated AF from 2015 to 2018 in our hospital. Such data were then matched with meteorological data, including air pollutant concentrations, collected by local weather stations. A case-crossover study was performed to assess the relationship between air pollutants and daily hospital visits for AF recorded by ECG and to investigate its lag effect. RESULTS: Our analysis revealed statistically significant associations between AF occurrence and demographic data, including age and gender. This effect was stronger in female (k = 0.02635, p < 0.01) and in patients over 65 y (k = 0.04732, p < 0.01). We also observed a hysteretic effect that when exposed to higher nitrogen dioxide(NO2), counting AF cases recorded by ECG may elevate at lag 0 with a maximum odds ratio(OR) of 1.038 (95% CI 1.014-1.063), on the contrary, O3 reduced the risk of daily visits for AF and its maximum OR was at lag 2, and the OR value was 0.9869 (95% CI 0.9791-0.9948). Other air pollutants such as PM2.5, PM10, and SO2 showed no clear relationship with the recorded AF. CONCLUSION: The associations between air pollution and AF recorded with ECG were preliminarily discovered. Short-term exposure to NO2 was significantly associated with daily hospital visits for AF management.

Dimensional accuracy and clinical adaptation of monolithic zirconia crowns fabricated with the nanoparticle jetting technique.

STATEMENT OF PROBLEM: The nanoparticle jetting (NPJ) technique is a recently developed additive manufacturing method that may have useful dental applications. The manufacturing accuracy and clinical adaptation of zirconia monolithic crowns fabricated with NPJ are unknown. PURPOSE: The purpose of this in vitro study was to compare the dimensional accuracy and clinical adaptation of zirconia crowns fabricated with NPJ and those fabricated with subtractive manufacturing (SM) and digital light processing (DLP). MATERIAL AND METHODS: Five standardized typodont right mandibular first molars were prepared for ceramic complete crowns, and 30 zirconia monolithic crowns were fabricated using SM, DLP, and NPJ (n=10) with a completely digital workflow. The dimensional accuracy at the external, intaglio, and marginal areas was determined by superimposing the scanned data and computer-aided design data of the crowns (n=10). Occlusal, axial, and marginal adaptations were evaluated by using a nondestructive silicone replica and dual scanning method. The 3-dimensional discrepancy was evaluated to determine clinical adaptation. Differences among test groups were analyzed by using a MANOVA and the post hoc least significant difference test for normally distributed data or the Kruskal-Wallis test with Bonferroni correction for nonnormally distributed data (α=.05). RESULTS: Significant differences were found in the dimensional accuracy and clinical adaptation among the groups (P<.001). The NPJ group had a lower overall root mean square (RMS) value for dimensional accuracy (22.9 ±1.4 µm) than the SM (27.3 ±5.0 µm) and DLP (36.4 ±5.9 µm) groups (P<.001). The NPJ group had a lower external RMS value (23.0 ±3.0 µm) than the SM group (28.9 ±5.4 µm) (P<.001) and equivalent marginal and intaglio RMS values than the SM group. The DLP group had larger external (33.3 ±4.3 µm), intaglio (36.1 ±10.7 µm), and marginal (79.4 ±12.9 µm) deviations than the NPJ and SM groups (P<.001). With regard to clinical adaptation, the marginal discrepancy was smaller in the NPJ group (63.9 ±27.3 µm) than in the SM group (70.8 ±27.5 µm) (P<.001). No significant differences were found between the SM and NPJ groups in terms of the occlusal (87.2 ±25.5 and 80.5 ±24.2 µm, respectively) and axial (39.1 ±19.7 and 38.4 ±13.7 µm, respectively) discrepancies. The DLP group had larger occlusal (239.0 ±60.1 µm), axial (84.9 ±29.1 µm), and marginal (140.4 ±84.3 µm) discrepancies than the NPJ and SM groups (P<.001). CONCLUSIONS: Monolithic zirconia crowns fabricated using NPJ have higher dimensional accuracy and clinical adaptation than those fabricated using SM or DLP.

Concentration prediction and spatial origin analysis of criteria air pollutants in Shanghai.

Severe air pollution events still occur frequently in Shanghai. In order to predict when Shanghai air quality satisfies the National Ambient Air Quality Standards of China (NAAQSC) and identify potential source areas of criteria air pollutants for the regional joint prevention and control of air pollution, concentration data of PM2.5, PM10, SO2, NO2 and O3 were collected in 2014-2022 at fourteen monitoring sites across Shanghai and surrounding areas. A first - order rate equation with harmonic regression analysis was employed for time series analysis and concentration prediction. Decreasing concentrations were observed widely over all sites except O3 and NO2. It is very likely that the secondary NAAQSC standards for PMx, and SO2 would be met by 2025 and O3 and NO2 would likely become the critical pollutants that determine air quality level after 2025. Regional transport was predominant for PMx and SO2 pollution. A 3D - CWT multisite joint location method was developed to identify their potential source areas at different spatial resolutions. Weighting function correction was assigned via information entropy of endpoint numbers in each cell. A probabilistic parameter WIPSA was proposed to quantify and normalize the probability that grid cells are source areas in order to achieve fourteen - site joint location, and it was comparable and compatible at different spatial resolutions. Potential source areas of PM2.5 and PM10 were similar, including Henan, Shandong, Hebei and Anhui, while origin domains of SO2 mainly covered Henan and Hebei. In all seasons, air pollution that was transported to Shanghai (i.e., PMx and SO2) originated mainly from the North China Plain; the contribution of marine sources was neglectable.

A digital workflow for single complete denture using a multi-functional diagnostic denture.

Creating a single complete denture against natural dentition can be challenging. To facilitate the clinical procedure and promote balanced occlusion, we developed a digital workflow of a single complete denture using a multi-functional diagnostic denture (DD). The DD was digitally designed and fabricated using a three-dimensional printing process to create a guide for tooth grinding in opposing dentition and a final impression that allows the jaw relationship and dynamic articulation to be recorded by an intraoral scanner. The definitive complete denture was combined with a milled artificial dentition and titanium-plated denture base. Within three clinical visits, this digital workflow provided better efficiency and easy implementation for a single complete denture.

Higher greenspace exposure is associated with a decreased risk of childhood asthma in Shanghai - A megacity in China.

Inconsistent evidence exists about whether exposure to greenspace benefits childhood asthma. Previous studies have only focused on residential or school greenspace, and no research has combined greenspace exposures at both homes and schools to determine their link with childhood asthma. A population-based cross-sectional study was conducted among 16,605 children during 2019 in Shanghai, China. Self-reported questionnaires were used to collect information on childhood asthma and demographic, socioeconomic and behavioural factors. Environmental data including ambient temperature, particulate matter with aerodynamic diameter less than 1 µm (PM1), enhanced vegetation index (EVI), and normalized difference vegetation index (NDVI) were collected from satellite data. Binomial generalized linear models with a logit link were carried out to evaluate the association between greenspace exposure and children's asthma, as well as the effect modifiers. An interquartile range increment of whole greenspace (NDVI500, NDVI250, EVI500, and EVI250) exposure was associated with a reduced odds ratio of children's asthma (0.88, 95% CI: 0.78, 0.99; 0.89, 95% CI: 0.79, 1.01; 0.87, 95% CI: 0.77, 0.99; and 0.88, 95% CI: 0.78, 0.99, respectively) after controlling potential confounders. Low temperature, low PM1, males, vaginal delivery, suburban/rural area, and without family history of allergy appeared to enhance the greenspace-asthma association. Increased greenspace exposure was associated with a lower risk of childhood asthma, and the association was modified by a range of socio-environmental factors. These findings add to the body of evidence on the benefits of biodiversity and supporting the promotion of urban greenspace to protect children's health.

Biomechanical evaluation of custom-made short implants with wing retention applied in severe atrophic maxillary posterior region restoration: A three-dimensional finite element analysis.

Severe bone atrophy in the maxillary posterior region poses a big challenge to implant restoration. Digitally designed and customized short implants with wing retention provide a safer and minimally invasive implant restoration scheme in such circumstances. Small titanium wings are integrated with the short implant supporting the prosthesis. Using digital designing and processing technology, the wings fixed by titanium screws can be flexibly designed, providing the main fixation. The design of the wings will influence the stress distribution and implant stability. This study analyzes the position, structure, and spread area of the wings fixture scientifically by means of three-dimensional finite element analysis. The design of the wings is set to linear, triangular, and planar styles. Under the simulated vertical and oblique occlusal forces, the implant displacement and stress between the implant and the bone surface are analyzed at different bone heights of 1 mm, 2 mm, and 3 mm. The finite element results show that the planar form can better disperse the stress. By adjusting the cusp slope to reduce the influence of lateral force, short implants with planar wing fixtures can be used safely even if the residual bone height is only 1 mm. The results of the study provide a scientific basis for the clinical application of this new customized implant.

Enhanced Antibacterial Effect on Zirconia Implant Abutment by Silver Linear-Beam Ion Implantation.

Peri-implant lesions, such as peri-implant mucositis and peri-implantitis, are bacterial-derived diseases that happen around dental implants, compromising the long-term stability and esthetics of implant restoration. Here, we report a surface-modification method on zirconia implant abutment using silver linear-beam ion implantation to reduce the bacterial growth around the implant site, thereby decreasing the prevalence of peri-implant lesions. The surface characteristics of zirconia after ion implantation was evaluated using energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and a contact-angle device. The antibacterial properties of implanted zirconia were evaluated using Streptococcus mutans and Porphyromonas gingivalis. The biocompatibility of the material surface was evaluated using human gingival fibroblasts. Our study shows that the zirconia surface was successfully modified with silver nanoparticles by using the ion-implantation method. The surface modification remained stable, and the silver-ion elution was below 1 ppm after one-month of storage. The modified surface can effectively eliminate bacterial growth, while the normal gingiva's cell growth is not interfered with. The results of the study demonstrate that a silver-ion-implanted zirconia surface possesses good antibacterial properties and good biocompatibility. The surface modification using silver-ion implantation is a promising method for future usage.

Residential greenspace and childhood asthma: An intra-city study.

Interest in assessing the effects of exposure to greenspace on human health has been increasing due to rapid urbanization, and rising trends of physical inactivity and air pollution. However, findings on the link between greenspace and child respiratory health, especially asthma, are inconsistent. We investigated the association between greenspace surrounding residential addresses and asthma in children. A city-wide cross-sectional study was conducted, involving 16,605 children aged 3-12 years, in Shanghai, China. Data on asthma symptoms and covariates were collected from validated self-reported questionnaires. Residential greenspace was measured using satellite-derived normalized difference vegetation index (NDVI) and enhanced vegetation index (EVI). Information on ambient temperature and particulate matter with dynamic diameter <1 µm (PM1) and 2.5 µm (PM2.5) was also collected from satellite data. Logistic regression models were performed to assess the associations of greenspace exposure with childhood asthma as well as the effect modification by covariates. The prevalence of current asthma in children was 4.8 % in this study. An interquartile range increase in mean NDVI from 2016 to 2018 was associated with decreased odds of asthma in 2019 at 500 m, and 250 m resolutions (0.82, 95 % confidence interval (CI): 0.74 to 0.93; and 0.82, 95 % CI: 0.72 to 0.94, respectively) after adjustment for covariates. The greenspace-asthma association was modified by ambient temperature and residential area. Sensitivity analyses using various models and EVI exposure showed the robustness of the results. In conclusion, higher individual-level exposure to greenspace was associated with decreased odds of asthma in children, and the association appeared to be modified by different environmental and socio-demographic factors. These findings provide additional evidence for promoting urban greenness to protect children's health and well-being.

Three-point sectional-cast digital method for transferring the interocclusal relationship for full-mouth rehabilitation of worn dentition.

For full-mouth rehabilitation of worn dentition, "diagnostic" interim restorations are required to reestablish the interocclusal relationship. It is important but challenging to transfer the interocclusal relationship and to map the basic form and contour of interim restorations to the final restorations. Alignment of interim restorations and working casts is difficult when using digital workflows because of a lack of consistent hard tissue reference points. The digital workflow presented in this study used a "3-point sectional-cast digital cross-mounting method" to transfer the interocclusal relationship during full-mouth rehabilitation. An intermediate cast was made with three interim restorations: one on an incisor and two on molars. The interocclusal relationship and occlusal morphologies of the diagnostic interim prostheses were transferred and aligned to working casts using the 3-point sectional casts.