The expression of CD86 in CD3+CD56+ NKT cells is associated with the occurrence and prognosis of sepsis-associated encephalopathy in sepsis patients: a prospective observational cohort study.

The role of CD3+CD56+ natural killer T (NKT) cells and its co-signaling molecules in patients with sepsis-associated encephalopathy (SAE) is unknown. In this prospective observational cohort study, we initially recruited 260 septic patients and eventually analyzed 90 patients, of whom 57 were in the SAE group and 37 were in the non-SAE group. Compared to the non-SAE group, 28-day mortality was significantly increased in the SAE group (33.3% vs. 12.1%, p = 0.026), while the mean fluorescence intensity (MFI) of CD86 in CD3+CD56+ NKT cells was significantly lower (2065.8 (1625.5 ~ 3198.8) vs. 3117.8 (2278.1 ~ 5349), p = 0.007). Multivariate analysis showed that MFI of CD86 in NKT cells, APACHE II score, and serum albumin were independent risk factors for SAE. Furthermore, the Kaplan-Meier survival analysis indicated that the mortality rate was significantly higher in the high-risk group than in the low-risk group (χ2 = 14.779, p < 0.001). This study showed that the decreased expression of CD86 in CD3+CD56+ NKT cells is an independent risk factor of SAE; thus, a prediction model including MFI of CD86 in NKT cells, APACHE II score, and serum albumin can be constructed for diagnosing SAE and predicting prognosis.

Efficacy of invisible advancement correction for mandibular retraction in adolescents based on Pancherz analysis.

BACKGROUND: Mandibular retraction is the main etiological mechanism of class II malocclusion in China and the subsequent distal molar relationship can cause functional discomfort in mastication, breathing and the temporomandibular joint. The use of mandibular advancement (MA) devices has recently emerged as an adolescent mandibular retraction treatment; however, current studies regarding the effect thereof are relatively few, and there is lack of sufficient clinical support. AIM: To investigate the clinical effect of invisalign MA on the treatment of mandibular retraction in adolescents. METHODS: This study included 30 adolescent patients who underwent treatment with the MA appliances from December 2017 to June 2021. The lateral cephalometric data before and after treatment were collected and imported into Dolphin Imaging software. The changes were measured by linear measurement superimposed with lateral cephalometric trajectory based on the Pancherz technology. RESULTS: There was no significant difference in the length and position of maxilla before and after the treatment. The position of the mandible moved 3.13 mm, the length increased 4.14 mm, the mandibular ramus length increased 4.09 mm, the body length increased 4.25 mm, and the position of the condyle moved 1.03 mm forward after treatment. Additionally, changes in the incisor sagittal position and labial inclination were observed. The position of the upper incisor point moved back 1.33 mm, without statistical difference, the inclination and tooth angle decreased by 3.44° and 4.06°, respectively; the position of the lower incisor point was moved 2.98 mm, and the inclination and tooth angle increased by 2.62° and 1.23°, respectively. Furthermore, changes in the incisor overjet and molar relationship were seen. Overjet decreased by 4.31 mm, of which 1.78 mm was due to dental factors, accounting for 41.3% of the effect as opposed to 58.7% due to skeletal factors. Molar relationship improved 3.87 mm, with 1.34 mm due to dental factors, and dental and skeletal factors were accounted for 34.6% and 65.4% of the effect, respectively. CONCLUSION: For adolescent patients with mandible retraction, invisalign MA can effectively promote the mandible growth, and it was proven to be mainly due to skeletal effects.

Stenting with high-intensity focused ultrasound ablation for distal biliary obstruction caused by pancreatic carcinoma: a meta-analysis.

Introduction: Between 42% and 77% of patients with distal malignant biliary obstruction (MBO) suffer from pancreatic carcinoma (PC). Aim: To analyse the clinical efficacy of stenting accompanied by high-intensity focused ultrasound (HIFU) ablation in patients with distal MBO from PC. Material and methods: Relevant articles published through March 2021 were identified in the Pubmed, Cochrane Library, Embase, Wanfang, VIP, and CNKI databases. RevMan v5.3 and Stata v12.0 were used for the meta-analysis. Results: Twenty-nine articles were initially identified, and 5 of these were eventually included. These articles described 142 patients who underwent biliary stenting alone and 132 patients who underwent biliary stenting with HIFU ablation. The pooled Δ total bilirubin (TBIL) values were comparable between the 2 treatment groups (p = 0.10). The pooled stent dysfunction rate was significantly greater in the group with stenting alone (p = 0.03), and the pooled HR for the stent patency duration indicated that the duration of stent patency was increased in the stenting with HIFU ablation group (p < 0.0001). Overall survival rates were significantly longer in the stenting with HIFU ablation group (p < 0.0001). HIFU ablation was associated with an 80% pooled clinical response rate. The pooled cholangitis (p = 0.47) and pancreatitis (p = 0.56) rates were comparable between the 2 groups. Funnel plots did not reveal any significant evidence of endpoint-associated publication bias. Conclusions: Stenting with HIFU ablation increased both stent patency and overall survival in patients with distal MBO caused by PC compared to stenting alone.

Benign pathologies results from lung nodule percutaneous biopsies: How to differentiate true and false benign?

OBJECTIVES: The objective was to identify predictors of true negatives in lung nodules (LNs) with computed tomography-guided percutaneous biopsy (CTPB)-based benign pathological results. MATERIALS AND METHODS: We included 90 total patients between January 2013 and December 2017 that had CTPB-based nonspecific benign pathologies and used these patients as a training group to accurately identify true-negative predictors. A validation group of 50 patients from January 2018 to June 2019 to confirm predictor reliability. RESULTS: CTPB was conducted on 90 LNs from the training group. True-negative and false-negative CTPB-based pathologies were obtained for 79 and 11 LNs, respectively. CTPB-based benign results had a negative predictive value of 87.8% (79/90). Univariate and multivariate analyses revealed younger age (P = 0.019) and CTPB-based chronic inflammation with fibroplasia (P = 0.010) to be true-negative predictors. A predictive model was made by combining these two prognostic values as follows: score = -7.975 + 0.112 × age -2.883 × CTPB-based chronic inflammation with fibroplasia (0: no present; 1: present). The area under receiver operator characteristic (ROC) curve was 0.854 (P < 0.001). To maximize sensitivity and specificity, we selected a cutoff risk score of -0.1759. The application of this model to the validation group yielded an area under the ROC curve of 0.912 (P < 0.001). CONCLUSIONS: Our predictive model showed good predictive ability for identifying true negatives among CTPB-based benign pathological results.

JAK/STAT signaling pathway-mediated microRNA-181b promoted blood-brain barrier impairment by targeting sphingosine-1-phosphate receptor 1 in septic rats.

BACKGROUND: Blood-brain barrier (BBB) impairment plays a significant role in the pathogenesis of sepsis-associated encephalopathy (SAE). However, the molecular mechanisms are poorly understood. In the present study, we aimed to investigate the regulatory relationship between the Janus kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway, microRNA (miR)-181b and its target genes in sepsis in vivo and in vitro. METHODS: Four rat models (sham, sepsis, sepsis plus STAT3 inhibitor (Stattic), and sepsis plus miR-181b inhibitor [sepsis + anta-miR-181b]) were established. For the in vitro experiments, rat brain microvascular endothelial cells (rBMECs) and rat brain astrocytes (rAstrocytes) were cultured with 10% serum harvested from sham, sepsis, and sepsis + anta-miR-181b rats. Chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP-QPCR) analysis was carried out to detect the binding and enrichment of the JAK/STAT3 signal core transcription complex in the miR-181b promoter region. Dual-luciferase reporter gene assay was conducted to test miR-181b and its target genes. The cell adhesion rate of rBMECs was also measured. RESULTS: During our investigations, the expression levels of miR-181b, p-JAK2, p-STAT3, and C/EBPß were found to be significantly increased in the septic rats compared with the sham rats. STAT3 inhibitor halted BBB damage by downregulating the expression of miR-181b. In addition, miR-181b targeted sphingosine-1-phosphate receptor 1 (S1PR1) and neurocalcin delta (NCALD). The up-regulated miR-181b significantly decreased the cell adhesion rate of rBMECs. The administration of miR-181b inhibitor reduced damage to the BBB through increasing the expression of S1PR1 and NCALD, which again proved that miR-181b negatively regulates SIPR1 and NCALD to induce BBB damage. CONCLUSIONS: Our study demonstrated that JAK2/STAT3 signaling pathway induced expression of miR-181b, which promoted BBB impairment in rats with sepsis by downregulating S1PR1 and decreasing BBB cell adhesion. These findings strongly suggest JAK2/STAT3/miR-181b axis as therapeutic target in protecting against sepsis-induced BBB damage.

[Expression and significance of chemokines CCL21, E-selectins and Hsp90 in periodontal tissues of rats with experimental periodontitis].

PURPOSE: To investigate the expression and significance of chemokines CCL21, E-selectins and heat shock protein 90 (Hsp90) in periodontal tissues of rats with experimental periodontitis. METHODS: Forty 10-week-old male Wistar rats were significantly randomly divided into 4 groups with 10 rats in each group. Periodontitis models were established in groups A, B and C, and the rest were 10 blank control groups. Rats in group A, B and C were sacrificed at 4, 8 and 12 weeks after basic periodontal treatment, and the periodontal tissues of the first and second molars were taken for CCL21, E-selectins and Hsp90 protein expression detection. SPSS 25.0 software package was used to analyze the data. RESULTS: The levels of periodontal attachment in group A, B and C were higher than those in the control group(P<0.05). The levels of periodontal attachment, CCL21, E-selectins, Hsp90 mRNA and protein expression in periodontal tissues increased first and then decreased(P<0.05). The levels of periodontal attachment, CCL21, E-selectins, Hsp90 mRNA and protein expression in group B and C were significantly higher than those in group A(P<0.05). The levels of periodontal attachment, CCL21, E-selectins, Hsp90 and relative protein expression in periodontal tissues of group C were significantly lower than those of group B(P<0.05). CONCLUSIONS: The expression of CCL21, E-selectins and Hsp90 is up-regulated in periodontitis tissues. With local periodontal treatment, the expression level of CCL21, E-selectins and Hsp90 gradually decreases.

Effects of dexmedetomidine on heart rate control and pre-operative outcome in patients with acute aortic dissection: a propensity-matched analysis.

BACKGROUND: The total survival rate in patients with acute aortic dissection (AAD) has been greatly improved because of surgical technique advances. However, the pre-operative mortality rate remained high. In this study, we sought to evaluate the effects of dexmedetomidine (DEX) on heart rate control and preoperative outcome in AAD. METHODS: Retrospectively enrolled 461 patients who were diagnosed with AAD during the first 7-day after admission and divided into two groups according to the use of intravenous DEX: DEX group (91 patients) and Control group (370 patients). The heart rate and systolic blood pressure (SBP) level in both groups were recorded, and the incidence of aortic dissection rupture and pre-operative survival rates within 7 days were considered as the primary clinical outcomes. RESULTS: Compared to the Control group, heart rate of DEX group in the early 3 hours was significantly higher (P=0.009), and the 24-hour heart rate fluctuation was smaller (P=0.012). There was no difference in the systolic blood pressure (SBP) between the two groups, but the 24-hour fluctuation of SBP in DEX group was less (P=0.003). We performed a propensity-matched analysis to minimize selection bias and found that there were 7 (7.9%) patients in the DEX group occurred acute pulmonary edema, 17 (19.1%) patients in the Control group (P=0.047). And the pre-operative survival rates within 7 days were significantly improved in DEX group (P=0.004). And the pre-operative survival rates within 7 days were significantly improved in DEX group (P=0.004). CONCLUSIONS: DEX can be beneficial to facilitate heart rate control, keep SBP more steady, and reduce the incidence of pre-operative aortic rupture in patients with AAD.

Hypercapnia promotes microglial pyroptosis via inhibiting mitophagy in hypoxemic adult rats.

BACKGROUND: Hypoxemia is a typical symptom of acute respiratory distress syndrome. To avoid pulmonary morbidity, low tidal volume ventilation is often applied. The ventilation strategy will certainly cause hypercapnia. This study aimed to explore whether hypercapnia would promote microglial pyroptosis via inhibiting mitophagy in adult rats with hypoxemia. METHODS: The cerebral oxygen extraction ratio (CERO2 ) and partial pressure of brain tissue oxygen (PbtO2 ) in a rat model of hypercapnia/hypoxemia were assessed. The reactive oxygen species (ROS) production and the expression of LC3-II/I, p62, caspase-1, gasdermin D-N domains (GSDMD-N), IL-1ß, and IL-18 in microglial cells were detected. RESULTS: Hypercapnia decreased the PbtO2 levels of the hypoxic rats, which was further evidenced by the increased levels of CERO2 . Expression levels of LC3-II were reduced, while p62 expression was increased by hypercapnia in hypoxic microglia. Hypercapnia increased the production of ROS and the expression of caspase-1, GSDMD-N, IL-1ß, and IL-18 in hypoxia-activated microglia. Scavenging ROS inhibited microglial pyroptosis and expression of IL-1ß and IL-18. CONCLUSIONS: These results suggest that hypercapnia-induced mitophagy inhibition may promote pyroptosis and enhance IL-1ß and IL-18 release in hypoxia-activated microglia.

Characterization of the Rifamycin-Degrading Monooxygenase From Rifamycin Producers Implicating Its Involvement in Saliniketal Biosynthesis.

Rifamycin derivatives, such as rifampicin, have potent antibiotic activity and have long been used in the clinic as mainstay components for the treatment of tuberculosis, leprosy, and AIDS-associated mycobacterial infections. However, the extensive usage of these antibiotics has resulted in the rapid development of bacterial resistance. The resistance mechanisms mainly include mutations of the rifamycin target RNA polymerase of bacteria and enzymatic modifications of rifamycin antibiotics. One modification is the recently characterized rifamycin degradation catalyzed by Rox enzymes, which belong to the widely occurring flavin monooxygenases. Intriguingly, our recent sequence analysis revealed the rifamycin producers also encode Rox homologs that are not yet characterized. In this work, we expanded the study of the Rox-catalyzed rifamycin degradation. We first showed that the Rox proteins from rifamycin producers have the enzymatic rifamycin SV-degrading activity. Then we used the structurally diverse rifamycin compounds rifampicin and 16-demethylrifamycin W to probe the substrate scope and found that they each have a slightly different substrate scope. Finally, we demonstrated that Rox proteins can also catalyze the transformation of 16-demethylsalinisporamycin to 16-demethylsaliniketal A. Since 16-demethylsalinisporamycin and 16-demethylsaliniketal A are the counterpart analogs of salinisporamycin and saliniketal A, our biochemical findings not only uncover a previously uncharacterized self-resistance mechanism in the rifamycin producers, but also bridge the gap between the biosynthesis of the potential antitumor compound saliniketal A.

Hypertonic saline mediates the NLRP3/IL-1ß signaling axis in microglia to alleviate ischemic blood-brain barrier permeability by downregulating astrocyte-derived VEGF in rats.

INTRODUCTION: The aim of this study was to explore whether the antibrain edema of hypertonic saline (HS) is associated with alleviating ischemic blood-brain barrier (BBB) permeability by downregulating astrocyte-derived vascular endothelial growth factor (VEGF), which is mediated by microglia-derived NOD-like receptor protein 3 (NLRP3) inflammasome. METHODS: The infarct volume and BBB permeability were detected. The protein expression level of VEGF in astrocytes in a transient focal brain ischemia model of rats was evaluated after 10% HS treatment. Changes in the NLRP3 inflammasome, IL-1ß protein expression, and the interleukin-1 receptor (IL1R1)/pNF-кBp65/VEGF signaling pathway were determined in astrocytes. RESULTS: HS alleviated the BBB permeability, reduced the infarct volume, and downregulated the expression of VEGF in astrocytes. HS downregulates IL-1ß expression by inhibiting the activation of the NLRP3 inflammasome in microglia and then downregulates VEGF expression by inhibiting the phosphorylation of NF-кBp65 mediated by IL-1ß in astrocytes. CONCLUSIONS: HS alleviated the BBB permeability, reduced the infarct volume, and downregulated the expression of VEGF in astrocytes. HS downregulated IL-1ß expression via inhibiting the activation of the NLRP3 inflammasome in microglia and then downregulated VEGF expression through inhibiting the phosphorylation of NF-кBp65 mediated by IL-1ß in astrocytes.

A preliminary study of the mechanism of nitrate-stimulated remarkable increase of rifamycin production in Amycolatopsis mediterranei U32 by RNA-seq.

BACKGROUND: Rifamycin is an important antibiotic for the treatment of infectious disease caused by Mycobacteria tuberculosis. It was found that in Amycolatopsis mediterranei U32, an industrial producer for rifamycin SV, supplementation of nitrate into the medium remarkably stimulated the yield of rifamycin SV. However, the molecular mechanism of this nitrate-mediated stimulation remains unknown. RESULTS: In this study, RNA-sequencing (RNA-seq) technology was employed for investigation of the genome-wide differential gene expression in U32 cultured with or without nitrate supplementation. In the presence of nitrate, U32 maintained a high transcriptional level of genes both located in the rifamycin biosynthetic cluster and involved in the biosynthesis of rifamycin precursors, including 3-amino-5-dihydroxybenzoic acid, malonyl-CoA and (S)-methylmalonyl-CoA. However, when nitrate was omitted from the medium, the transcription of these genes declined sharply during the transition from the mid-logarithmic phase to the early stationary phase. With these understandings, one may easily propose that nitrate stimulates the rifamycin SV production through increasing both the precursors supply and the enzymes for rifamycin biosynthesis. CONCLUSION: It is the first time to thoroughly illustrate the mechanism of the nitrate-mediated stimulation of rifamycin production at the transcriptional level, which may facilitate improvement of the industrial production of rifamycin SV, e.g. through optimizing the global rifamycin biosynthetic pathways on the basis of RNA-seq data.

[Solitary median maxillary central incisor syndrome:a case of report].

Solitary median maxillary central incisor (SMMCI) is a rare dental anomaly characterized by a symmetric central incisor of normal size, developed and erupted precisely in the midline of the maxilla in both primary and permanent dentitions. SMMCI may occur alone or be associated with other midline structures defects of the body or other systemic disorders. The best known association is holoprosencephaly (HPE). This paper reported a case of SMMCI that companied with other midline structures defects of the body.

[Effect of different orthodontic interproximal reduction methods on the enamel].

PURPOSE: To find a suitable interproximal enamel (IER) reduction method for clinical use by pH cycles in vitro. METHODS: 50 human premolars extracted for orthodontic reasons were collected for the experiment. After removal of the roots, the crowns were split vertically into two halves with wafer-thin wheel blade. Then the 100 samples were randomly divided into 5 groups, 20 samples for each group. The enamel in each group was reduced with different IER methods: group I, stripping strip; group II, stripping disk; group III, stripping strip with polishing system and 35% orthophosphoric acid; group IV, stripping disk with polishing system and 35% orthophosphoric acid; group V, no treatment control group. All the samples were treated with pH cycles in vitro for 30 days. The microhardness of enamel surface of all samples was detected by microhardness testing machine. The enamel surface morphology of microstructure was examined by scanning electron microscopy(SEM).The data was analyzed with SPSS13.0 software package. RESULTS: 1.ANOVA detected statistically significant differences between groups. The post SNK-q test showed that there was no significant difference between group I and group II, between group III and group IV(P>0.05); But there was significant difference between group I and group III, group I and group IV, group II and group III, group II and group IV(P<0.01). And there was significant difference between group I and group V, group II and group V, group III and group V, group IV and group V(P<0.05). 2.From naked eye and SEM, there was no distinct difference between the two chemical polishing groups, but better than the others. CONCLUSIONS: 1.There is no significant difference between strip and disk after IER. 2.Chemical polishing group is better than the others after IER. 3.The scratches of the enamel surface caused by IER are hardly repaired even after remineralization.

[Comparative study on the apical root resorption between self-ligating and conventional brackets in extraction patients].

PURPOSE: To explore whether orthodontic light force with self-ligating brackets can reduce the amount of external apical root resorption (EARR). METHODS: Thirty patients with Class I or II crowding malocclusion were selected. Four first premolars of all patients were extracted in orthodontic treatment. 15 patients were treated with self-ligating brackets (Damon 3MX) and 15 patients with conventional ligation brackets, respectively. Patients in two groups were comparable in gender, age, crowded degree and malocclusion classification at the commencement of treatment. EARR of the maxillary and mandible incisors was evaluated on panoramic radiographs and models taken before and after treatment, and measured in millimeters. Student's t test was performed using SPSS19.0 software package. RESULTS: Overall, no difference was found in the amount of EARR between the two groups. The amount of EARR in maxillary central incisor was (2.05±1.51) mm in Damon group and (2.08±1.21) mm in conventional group(P=0.973>0.05); (1.77±1.01) mm in maxillary lateral incisor in Damon group and (1.91±1.59) mm in conventional group(P=0.848>0.05); (2.06±1.62) mm in mandibular central incisor in Damon group and (1.98±1.50) mm in conventional group(P=0.926>0.05); (1.94±1.45) mm in mandibular lateral incisor in Damon group and (1.84±1.17) mm in conventional group(P=0.888>0.05). CONCLUSION: No difference should be expected for root resorption between self-ligating and conventional brackets in orthodontic extraction treatment.

[Color changes induced by fluoride on nickel-titanium orthodontic wires].

OBJECTIVE: To observe the color changes of nickel-titanium (Ni-Ti) orthodontic wires induced by fluoride. METHODS: Each 40 samples of 4 kinds of nickel-titanium orthodontic wires (IMD, SL, TP, YY) were put into artificial saliva with sodium fluoride at different F concentrations (0.05%, 0.10%, 0.15%) and artificial saliva, separately. Dislodged the species and immersed them into artificial saliva with sodium fluoride for 3 minutes, then washed them with deionized water, and put back to artificial saliva, this course should be repeated 3 times per day. The whole immersion test lasted for 28 days. The color and micro-morphous changing were observed. RESULTS: The color changes came to be more serious as the F- concentration growing (P < 0.05). At the same F- concentration, the color changes of IMD and YY were higher than SL and YP (P < 0.01), while there were no significant difference between IMD and YY, SL and TP (P > 0.05). CONCLUSION: Fluoride can change the color of Ni-Ti wire. Different Ni-Ti wires get different changes at the same F- concentration.

[Correlation analysis on the malocclusion and articulation of skeletal angle III malocclusion in mixed dentition].

OBJECTIVE: To investigate the effects of skeletal Class III malocclusion in mixed dentition on speech articulation and to look for which factors lead to the speech errors. METHODS: Thirty-eight children with skeletal Angle Ill malocclusion in mixed dentition were selected as a sample group and 40 children with normal occlusion in mixed dentition as a control group. Two phoneticians evaluated their articulations and wrote down error phonemes respectively. The correlation analysis was undertaken between the number of errors and the measurements of patients' cephalometry. RESULTS: The number of errors were correlated significantly with overbite, UI-LI, OBJ (OB+OJ) and TD-PW. CONCLUSION: There is articulatory malfunction in the majority of skeletal Angle III malocclusion patients in mixed dentition. Articulatory malfunction is related to the position of incisors and the tongue.

[Changes in mastication efficiency before and after orthodontic treatment of adult skeletal angle III malocclusion].

PURPOSE: To evaluate the changes of mastication efficiency pre- and post-treatment in adult skeletal Angle III malocclusion, and to analyze the effect of malocclusion on mastication efficiency. METHODS: Masticatory efficiency was analyzed in 60 patients with adult skeletal Angle III malocclusion pre- or post-orthodontic treatment and 30 adults with normal occlusion as controls. Masticatory efficiency was measured by means of a spectrophotometer using Gelatin. SPSS 10.0 software package was used for Student's t test and step-wise regression. RESULTS: (1) Significant difference of masticatory efficiency was found among the three groups (P < 0.001). Multiple comparision showed significant difference among pre-treatment group, post-treatment group and normal controls (P < 0.05). (2) Step-wise regression results suggest that overjet and mandibular prognathism were closely related to masticatory efficiency in both pre- and post-treatment group. CONCLUSION: Orthodontic therapy can improve masticatory function in patients with malocclusion.

[Influence of different porcelain surface treatment method on the bonding of metal brackets to porcelain].

OBJECTIVE: To investigate the influence of different porcelain surface treatment methods on the shear bond strength of metal brackets bonded to porcelain. METHODS: 80 porcelain facets were divided randomly into two groups according to different adhesive material that was used to bond metal brackets. Adhesive material were Jing-Jin enamel adhesive and light-cured composite resin. Each group was further divided into 4 subgroups according to different surface treatment methods, which were acid etching with 37% phosphoric acid (H3PO4), acid etching with 9.6% hydrofluoric acid (HF), deglazing by grinding and silanating the porcelain surface. All specimens were stored in 37 degrees C water for 24 hours and then the shear bond strength and the porcelain fracture after debonding was determined. The porcelain surfaces after HF etching, H3PO4 etching and deglazing by grinding were examined by scanning electron microscopy respectively. RESULTS: The shear bond strengths in the HF etching groups, the deglazing groups and the silanating groups were much greater than that in the phosphoric etching groups (P < 0.01). Adequate orthodontic bonding strength was achieved both when bonded with light-cured composite resin after deglazing by grinding and when bonded with either of these adhesives after HF etching or surface silanating. There were no differences in the rates of porcelain fractures among groups (P > 0.05). CONCLUSION: HF etching, deglazing by grinding and silanating can all increase the shear bond strength between metal bracket and porcelain. Surface silanating of porcelain is a better surface treatment when metal brackets bonded to porcelain.

[Effect of bonding materials and methods on microleakage around the edge of stainless-steel brackets: an in vitro study].

PURPOSE: To observe and compare the effect of different types of adhesive materials and different types of etching methods on microleakage around bonded metal brackets. METHODS: 36 healthy premolars extracted for orthodontic reason were selected in the study. The samples were divided into three groups, 12 in each. Group A was etched with 37% phosphate and bonded with Jingjin adhesive; Group B was with 37% phosphate+3M Transbond; Group C was self-etching primer+3M Transbond. All samples were thermalcycled for 500 times, then put into 1% methylenum solution for 24 hours. Microleakage of samples was observed under stereomicroscope. Multiple comparison and Student t test were used for the comparison of data samples(alpha=0.05). RESULTS: (1) Significant difference of microleakage was found among three groups (F=22.462, P<0.01); Multiple comparison showed no significant difference between Group A and Group B (P>0.05), significant differences of microleakage were found between group A and C (P<0.05), group B and C (P<0.05), respectively. (2) Significant differences between occlusal microleakage and gingival microleakage were found in group A (P<0.05), group B (P<0.01) and group C (P<0.01), respectively. CONCLUSIONS: (1) The type of adhesive had no effect on microleakage. (2)Different etching methods are relevant to microleakage, the microleakage of self-etching groups is much more than that of phosphate-etching groups. (3) Gingival microleakage is significantly larger than occlusal microleakage.

[A statistic analysis on absence of third molar germs in orthodontic patients].

OBJECTIVE: To examine the absence of the third molar germs in orthodontic patients and to evaluate the relationship between third molar germs and malocclusion. METHODS: The subjects comprised 234 patients (male 92, female 142) from the orthodontic clinic whose ages were 14-18. The assessments of the third molar germs were made from panoramic radiographs, and the assessments of ANB angle were made from lateral cephalograms. All the data were analyzed by statistic chi2 test. RESULTS: The percentage of male who missed one or more third molar gems (37.0%) was higher than that of female (24.6%). There was no significant difference between the absent frequencies of third molar germs on left and right sides in either maxilla or mandible. The absent percentage of third molar germs in skeletal III subjects was higher than those in both skeletal class I and II subjects. The absent difference of third molar germs was in upper arches (P < 0.05), but not in lower arches (P > 0.05). There was no significant difference in absent percentage of third molar germs between skeletal class I and II subjects. CONCLUSION: Male patients have higher absent frequencies of third molar germs than female ones. Skeletal class III patients have higher absence of third molar germs in upper jaws than skeletal class I and II patients.