Analysis of risk factors for complications following transurethral resection of the prostate.

OBJECTIVE: This study investigates the risk factors for complications following transurethral resection of the prostate and provides a reference for reducing postoperative complications. PATIENTS AND METHODS: A retrospective analysis was conducted on 322 patients with benign prostatic hyperplasia who underwent transurethral resection of the prostate from April 2015 to January 2022. Among them, 214 patients had complete clinical and follow-up data. Clinical and follow-up data were collected, and both univariate and multivariate logistic regression analyses were performed to identify factors influencing the occurrence of postoperation transurethral resection of the prostate complications. RESULTS: The incidence of complications after transurethral resection of the prostate was 19.16% (41/214). Among them, the incidence of Grade I-II complications was 14.96% (32/214), and Grade III-IV complications were 4.2% (9/214). The preoperative Quality of Life score (p<0.001) was identified as an independent risk factor for the occurrence of Grade I-II complications after transurethral resection of the prostate. The International Prostate Symptom Score (p=0.006) was identified as an independent risk factor for the occurrence of Grade III-IV complications after transurethral resection of the prostate. CONCLUSIONS: The preoperative Quality of Life score is an independent risk factor for the occurrence of Grade I-II complications after transurethral resection of the prostate. The International Prostate Symptom Score is an independent risk factor for the occurrence of Grade III-IV complications after transurethral resection of the prostate.

[Cytopathological characteristics of SMARCA4-deficient thoracic undifferentiated tumors in serous effusion].

Objective: To investigate the clinicopathological characteristics of SMARCA4-deficient thoracic undifferentiated tumors, and the diagnostic value of the cells in serous effusion. Methods: Eleven cases of SMARCA4-deficient tumor were collected from the Affiliated Hospital of Hebei University, China from January 2018 to July 2023, which were diagnosed using cell block of serous effusion. The clinical, histopathological, immunohistochemical and molecular genetic features were reviewed, along with related literature. Results: All the 11 patients were males with ages ranging from 54 to 77 years (median 64 years). Nine patients were smokers and two had an unknown smoking history. Most of them complained of cough and dyspnea with pleural effusion. The primary tumor sites included lung (9 cases), thoracic wall (1 case), and mediastinum (1 case), while 3 patients had a history of lung surgery. Histologically, tumor cells were large and pleomorphic, with increased nuclear-cytoplasmic ratio. They also showed round nuclei, conspicuous nucleoli, and basophilic cytoplasm in serous effusion. Immunohistochemically, tumor cells in all cases were negative for SMARCA4/BRG1, CKpan and CK7, but positive for SMARCB1/INI1. Some of the cases were positive for CD34 (7/11), synaptophysin (4/11) and SALL4 (2/11). Histologically, monotonous tumor cells formed solid sheets or anastomosing islands with poor cell adhesion and rhabdoid morphology. Brisk mitotic figures were accompanied by large areas of necrosis. Some cases focally exhibited syncytia, and some had bright cytoplasm and vesicular chromatin. The immunohistochemical profiles in the tumor tissues were consistent with those of cytology. Six cases were negative for PD-L1 (22c3). Among the 6 cases analyzed by targeted next generation sequencing, concurrent SMARCA4 and TP53 mutations were detected in all 6 cases. Some of the 6 tumors showed mutations of STK11, CDKN2A, and MET, and amplification of ERBB2, exon deletion of BRCA2, etc. Follow-up information was available in all cases and ranged from 2 to 24 months. The patients showed metastases to various sites, including lymph node, liver, kidney, adrenal gland, brain, bone and other sites. Four patients died of the tumor. The survival time of 4 patients who underwent radical resection or radiofrequency ablation was more than 13 months. Conclusions: SMARCA4-deficient thoracic sarcoma is a rare but highly aggressive tumor with dismal prognosis and rhabdomyoid features. It is difficult to diagnose this disease using only serous effusion samples. This tumor thus warrants careful consideration. Accurate diagnosis can greatly improve early diagnosis and treatment of these tumors.

Single-cell transcriptomics reveals the heterogeneity of the decidual endothelial cells that participate in labor onset.

OBJECTIVE: To investigate the heterogeneity of decidual endothelial cells and their changes during delivery. PATIENTS AND METHODS: Single-cell RNA sequencing was used to characterize the transcriptomes of decidual endothelial cells before and after the onset of labor. RESULTS: Decidual endothelial cells (9748 cells) were divided into five subgroups with different functions according to differences in the transcriptome. The functions of cluster 5 were enriched in vascular development and response to growth factors. After the onset of labor, the activities of each cluster were different, including the interleukin 17 pathway and regulation of ERK1 and ERK2 cascade. The downregulated genes were related to scavenger receptor (cluster 5), which may reflect the process of endothelial activation. In terms of genetic changes, cluster 5 may be more actively involved in labor than the other clusters. CONCLUSIONS: Peripartum decidual endothelial cells are heterogeneous and participate in labor to varying degrees. One of the five subtypes of endothelial cells may be more actively involved in labor onset. Our findings may enable the assessment of decidual endothelial cells and labor onset.

Association of disease condition with changes in intestinal flora, and plasma endotoxin and vascular endothelial growth factor levels in patients with liver cancer.

OBJECTIVE: Currently, the therapeutic effect on patients with liver cancer is associated with disease development. Meanwhile, the efficacy in patients with advanced liver cancer is far from satisfactory. Therefore, the aim of this study was to explore the association of disease condition with changes in liver function indexes, intestinal flora, and plasma endotoxin (ET) and vascular endothelial growth factor (VEGF) levels in patients with liver cancer. PATIENTS AND METHODS: A total of 300 patients with primary liver cancer in our hospital were enrolled in this study. All patients were divided into three groups, including early liver cancer group, middle liver cancer group, and advanced liver cancer group. Peripheral blood was collected from each subject to detect liver function indexes, procalcitonin (PCT), plasma ET, and VEGF levels. Furthermore, mid-posterior-segment stools were collected from 15 cases in each group, and sent to the company for detection of intestinal flora. RESULTS: Liver function indexes in peripheral blood of patients with liver cancer changed with the changes in disease condition. With the progression of liver cancer, the level of aspartate aminotransferase (AST) increased significantly, and the highest was observed in advanced liver cancer patients [(91.18±10.34) U/L] (p=0.046). However, the level of plasma total protein declined significantly, which was (24.83±1.75) g/L in advanced liver cancer patients (p=0.035). The changes in total bilirubin were significantly associated with the progression of liver cancer (p=0.003). The abundance of Clostridiales, Firmicutes, and Streptococcus in the intestinal tract was high in early liver cancer group. The abundance of Ruminococcaceae, Pasteurellaceae, Tanticharoenia, and Vagococcus in the intestinal tract was high in middle liver cancer group. Meanwhile, the abundance of Bifidobacteriales, Actinobacteria, Barnesiella, Porphyromonadaceae, and Pseudomonadales in the intestinal tract was high in advanced liver cancer group. In patients with liver cancer, the level of Enterobacteriaceae was positively correlated with that of Firmicutes (r=0.36, p=0.003), whereas it was negatively correlated with Lactobacillus (r=-0.72, p=0.021). The level of Lactobacillus was positively correlated with that of Ruminococcaceae (r=0.39, p=0.043), whereas it was negatively correlated with that of Firmicutes (r=-0.27, p=0.019). In addition, the level of PCT markedly rose in advanced liver cancer group [(6.89±0.35) ng/mL] (p=0.021). The level of ET increased significantly with the development of liver cancer, with the highest level observed in advanced liver cancer group [(0.71±0.09) EU/mL] (p=0.004). The level of VEGF also increased remarkably with the aggravation of liver cancer, and the highest was found in advanced liver cancer group [(112.33±2.11) µmol/L], showing differences among groups (p<0.05). CONCLUSIONS: With the progression of liver cancer, the abundance of Barnesiella, etc., rose and that of Ruminococcaceae, etc., declined in the intestinal tract. Meanwhile, the composition of intestinal flora was changed, and the levels of plasma ET and VEGF increased.

[Comparison of the clinical characteristics between RNA positive and negative patients clinically diagnosed with coronavirus disease 2019].

Objective: To raise awareness about 2019 novel coronavirus pneumonia (NCP) and reduce missed diagnosis rate and misdiagnosis rate by comparing the clinical characteristics between RNA positive and negative patients clinically diagnosed with NCP. Methods: From January 2020 to February 2020, 54 patients who were newly diagnosed with NCP in Wuhan Fourth Hospital were included in this study. RT-PCR method was used to measure the level of 2019-nCov RNA in pharyngeal swab samples of these patients. The patients were divided into RNA positive and negative group, and the differences of clinical, laboratory, and radiological characteristics were compared. Results: There were 31 RNA of 2019-nCov positive cases, and 23 negative cases. Common clinical symptoms of two groups were fever (80.64% vs. 86.96%) , chills (61.29% vs. 52.17%) , cough (80.64% vs. 95.65%) , fatigue (61.30% vs. 56.52%) , chest distress (77.42% vs.73.91%) . Some other symptoms were headache, myalgia, dyspnea, diarrhea, nausea and vomiting. The laboratory and radiological characteristics of two groups mainly were lymphopenia, increased erythrocyte sedimentation rate, increased C-reactive protein, increased lactate dehydrogenase, decreased oxygenation index, normal white blood cell count and bilateral chest CT involvement. There was no statistically significant difference in other clinical characteristics except for dyspnea between two groups. Conclusions: RNA positive and negative NCP patients shared similar clinical symptoms, while RNA positive NCP patients tended to have dyspnea. Therefore, we should improve the understanding of NCP to prevent missed diagnosis and misdiagnosis; In addition, more rapid and accurate NCP diagnostic approaches should be further developed.

MicroRNA-214-3p: A link between autophagy and endothelial cell dysfunction in atherosclerosis.

AIM: Endothelial cell injury assumes a fundamental part in the pathogenesis of atherosclerosis, and endothelial cell autophagy has protective effects on the development of atherosclerosis, although the underlying molecular regulation mechanism is indistinct. This study aimed to investigate whether microRNA-214-3p (miR-214-3p) is involved in the endothelial cell autophagy regulation of atherosclerosis. METHODS: We utilized ApoE-/- mice provided with a high-fat diet (HFD) as atherosclerosis model. We analysed the level of miR-214-3p and the levels of autophagy-related protein 5 (ATG5) and autophagy-related protein 12 (ATG12) in the purified CD31+ endothelial cells from mouse aorta. Bioinformatics analysis and a dual-luciferase reporter assay were performed to confirm the binding target of miR-214-3p. In vitro study, human umbilical vein endothelial cells (HUVECs) were transfected with miR-214-3p mimics/inhibitor and stimulated with 100 µg/mL oxidized low-density lipoprotein (ox-LDL) for 12 hours to initiate a stress-repairing autophagic process. RESULTS: In mouse models, we identified an inverse correlation between miR-214-3p, ATG5 and ATG12. We observed that in young HUVECs, ox-LDL-initiated autophagy was repressed by miR-214-3p overexpression, as evaluated by autophagic protein analysis, microtubule-associated protein 1 light chain 3B-II (LC3B-II) immunofluorescence assay and transmission electron microscopy (TEM). Also, miR-214-3p promoted ox-LDL accumulation in HUVECs and THP-1 monocyte adhesion. Conversely, in old HUVECs, suppression of miR-214-3p preserved the ability to initiate a protective autophagy reaction to the ox-LDL stimulation. CONCLUSION: miR-214-3p regulates ox-LDL-initiated autophagy in HUVECs by directly targeting the 3'UTR of ATG5 and may have a suitable role in the pathogenesis of atherosclerosis.

[A preliminary study on the forming quality of titanium alloy removable partial denture frameworks fabricated by selective laser melting].

Objective: To evaluate the processing accuracy, internal quality and suitability of the titanium alloy frameworks of removable partial denture (RPD) fabricated by selective laser melting (SLM) technique, and to provide reference for clinical application. Methods: The plaster model of one clinical patient was used as the working model, and was scanned and reconstructed into a digital working model. A RPD framework was designed on it. Then, eight corresponding RPD frameworks were fabricated using SLM technique. Three-dimensional (3D) optical scanner was used to scan and obtain the 3D data of the frameworks and the data was compared with the original computer aided design (CAD) model to evaluate their processing precision. The traditional casting pure titanium frameworks was used as the control group, and the internal quality was analyzed by X-ray examination. Finally, the fitness of the frameworks was examined on the plaster model. Results: The overall average deviation of the titanium alloy RPD framework fabricated by SLM technology was (0.089±0.076) mm, the root mean square error was 0.103 mm. No visible pores, cracks and other internal defects was detected in the frameworks. The framework fits on the plaster model completely, and its tissue surface fitted on the plaster model well. There was no obvious movement. Conclusions: The titanium alloy RPD framework fabricated by SLM technology is of good quality.

The localization of SP-B and influences of lipopolysaccharide on it.

OBJECTIVE: Surfactant protein B (SP-B) is the only essential protein component of lung surfactant, the relationship between localization and function is very close. The localization of rat SP-B and influences of lipopolysaccharide (LPS) on it were investigated. MATERIALS AND METHODS: The localization of SP-B protein in lung tissue was detected by immunofluorescence after challenged with intratracheal instillation of LPS. The constructed recombinant plasmid pEGFP-N2-SP-B was transfected with CCl-149 cell lines by liposome to explore the localization of SP-B in alveolar type II epithelial cells. Furthermore, the expression and function of SP-B were analyzed with LPS stimulating. RESULTS: The proteins SP-B and SP-C showed the same pattern of expression in normal lung, and distributed in the alveolar cavity, LPS can directly affect the expression of SP-B in vivo, contrast to SP-B, the LPS-induced influences on SP-C is little. SP-B had the membrane embedded features and localized on the cell surface of CCL149 in vitro, but was influenced by LPS. CONCLUSIONS: It is confirmed that the expression and membrane function of SP-B were decreased by stimulating LPS in lung tissue and alveolar type II epithelial cells.

Molecular characterization and function of a PTEN gene from Litopenaeus vannamei after Vibrio alginolyticus challenge.

PTEN, a tumor suppressor gene, suppresses cell survival, growth, apoptosis, cell migration and DNA damage repair by inhibiting the PI3K/AKT signaling pathway. In this study, the full-length Litopenaeus vannamei PTEN (LvPTEN) cDNA was obtained, containing a 5'UTR of 59bp, an ORF of 1269bp and a 3'UTR of 146bp besides the poly (A) tail. The PTEN gene encoded a protein of 422 amino acids with an estimated molecular mass of 48.3 KDa and a predicted isoelectric point (pI) of 7.6. Subcellular localization analysis revealed that LvPTEN was distributed in both cytoplasm and nucleus, and the tissue distribution patterns showed that LvPTEN was ubiquitously expressed in all the examined tissues. Vibrio alginolyticus challenge induced upregulation of LvPTEN expression. Moreover, RNAi knock-down of LvPTEN in vivo significantly increased the expression of LvAKT mRNA, while reducing that of the downstream apoptosis genes LvP53 and LvCaspase3. LvPTEN knock-down also caused a sharp increase in cumulative mortality, bacterial numbers, and DNA damage in the hemolymph of L. vannamei following V. alginolyticus challenge, together with a sharp decrease in the total hemocyte count (THC). These results suggested that LvPTEN may participate in apoptosis via the PI3K/AKT signaling pathway in L. vannamei, and play an important role in shrimp innate immunity.

Protective effects of hydrogen-rich medium on lipopolysaccharide-induced monocytic adhesion and vascular endothelial permeability through regulation of vascular endothelial cadherin.

We observed the effect of hydrogen-rich medium on lipopolysaccharide (LPS)-induced human umbilical vein endothelial cells (HUVECs), hyaline leukocyte conglutination, and permeability of the endothelium. Endotheliocytes were inoculated on 6-well plates and randomly divided into 4 groups: control, H2, LPS, LPS+H2, H2, and LPS+H2 in saturated hydrogen-rich medium. We applied Wright's stain-ing to observe conglutination of hyaline leukocytes and HUVECs, flow cytometry to determine the content of vascular cell adhesion protein 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1), enzyme-linked immunosorbent assay to measure the E-selectin concentration in the cell liquor, the transendothelial electrical resistance (TEER) to test the permeability of endothelial cells, and Western blot and immunofluorescence to test the expression and distribution of vascular endothelial (VE)-cadherin. Compared with control cells, there was an increase in endothelium-hyaline leukocyte conglutination, a reduction in VCAM-1, ICAM-1, and E-selectin, and the TEER value increased obviously. Compared with LPS, there was an obvious reduction in the conglutination of LPS+H2 cells, a reduction in VCAM-1, ICAM-1, and E-selectin levels, and a reduction in the TEER-resistance value, while the expression of VE-cadherin increased. Fluorescence results showed that, compared with control cells, the VE-cadherin in LPS cells was in-complete at the cell joints. Compared with LPS cells, the VE-cadherin in LPS+H2 cells was even and complete at the cell joints. Liquid rich in hydrogen could reduce LPS-induced production of adhesion molecules and endothelium-hyaline leukocyte conglutination, and influence the expression and distribution of VE-cadherin to regulate the permeability of the endothelium.

Glucosamine: fructose-6-phosphate amidotransferase in the white shrimp Litopenaeus vannamei: characterization and regulation under alkaline and cadmium stress.

Heavy metal residues and chemical contaminators considered as relevant sources of aquatic environmental pollutants have a generally immunosuppressive effect on aquatic organisms, depressing metabolic activities and immune response. Glutamine: fructose-6-phosphate aminotransferase (GFAT, EC2.6.1.16) is the first, and rate-limiting, enzyme in the hexosamine biosynthetic pathway, and is involved in the regulation of chitin biosynthesis and glycosylation of proteins. We have isolated and characterized GFAT from the white shrimp Litopenaeus vannamei. Amino acid sequence similarity of the Lv-GFAT (L.vannamei-GFAT) was highest to GFATs isolated from insects and mammals (83 % similarity to that of Haemaphysalis longicornis). The open-reading frame of the Lv-GFAT codes for a protein of 41.6 kDa with a calculated isoelectric point of 5.03. RT-PCR assays showed that endogenous Lv-GFAT mRNA is most strongly expressed in the intestine. Further analysis of Lv-GFAT gene expression in hepatopancreas by quantitative real-time PCR demonstrated that Lv-GFAT transcript levels increased when the shrimp were exposed to alkaline pH (9.3) and cadmium stress, but the time when its mRNA expression level peaked differed under these stresses. We also first expressed the recombinant protein of GFAT from shrimps in Escherichia coli. Western blot analyses confirmed that the Lv-GFAT protein was strongly expressed in the hepatopancreas after exposure to the LC-Cd stress. These results suggest that Lv-GFAT expression is stimulated by alkaline pH and cadmium stress and that it may play important roles in resistance of shrimp to environmental stresses.

Negative appendicectomy rate as a quality metric in the management of appendicitis: impact of computed tomography, Alvarado score and the definition of negative appendicectomy.

INTRODUCTION: The negative appendicectomy rate (NAR) is a quality metric in the management of appendicitis. While computed tomography (CT) has been associated with a low NAR, Alvarado scoring produces an acceptable NAR. The definition of negative appendicectomy may affect the NAR. This study examined the impact of CT, Alvarado score and definition on the NAR. METHODS: The charts of 1,306 emergency appendicectomy patients from 1996 to 2010 were reviewed. Three five-year cohorts were created (Cohort A: 1996-2000, Cohort B: 2001-2005, Cohort C: 2006-2010) and the NAR was calculated for each cohort using two definitions of negative appendicectomy: absence of inflammation (NAR-STD) and absence of intramural neutrophils (NAR-STR). NAR-STD was correlated to the CT rate for Cohorts B and C and also to Alvarado score for Cohort C. RESULTS: When the definition of negative appendicectomy was changed, the NAR rose from 9.2% to 15.8% (p=0.0097) for Cohort A, from 2.8% to 8.6% (p=0.0180) for Cohort B (CT rate: 80.6%) and from 3.0% to 6.7% (p=0.0255) for Cohort C (CT rate: 92.4%). The introduction of CT lowered NAR-STD from 1996-2000 (9.2%) to 2001-2010 (2.9%) but increasing the CT rate from 2001-2010 had no impact on the NAR. The positive predictive value for Alvarado score (98.60%) and CT (99.03%) were similar. CONCLUSIONS: The definition of a negative appendicectomy determines the NAR. CT reduces the NAR regardless of definition but routine CT is unnecessary for male patients with positive Alvarado scores. Early/mild appendicitis may resolve without surgery and CT may contribute to unnecessary surgery. Alvarado scoring allows selective use of CT in suspected appendicitis.

Postgraduate year does not influence operating time in laparoscopic cholecystectomy.

BACKGROUND: Surgical resident education may contribute to increased operating time, thus increasing costs at teaching institutions. It is possible that junior residents, in particular, with less experience could contribute to longer operating times for laparoscopic cholecystectomy. We hypothesized that all general surgery residents, regardless of level of training and with proper supervision, could complete a laparoscopic cholecystectomy in a safe and timely fashion. MATERIALS AND METHODS: A retrospective study was performed using data collected from laparoscopic cholecystectomies completed under the supervision of one attending surgeon over a 2-year period. Operating times were recorded, the operating surgeon was identified, and cases were assigned an acuity level based on pathologic findings. Operative times were compared after dividing surgeons into three groups (junior residents, senior residents, and staff). RESULTS: Seventy-one cases were entered into the study. There were no differences when comparing mean operating times among the three groups (P = 0.2, analysis of variance). The pathologic acuity in each group was similar (P = 0.8, Fisher's exact test). There was a difference when evaluating the operating times for the pathologic level of acuity (P = 0.002, Kruskal-Wallis test). CONCLUSIONS: Resident level does not affect the operating time in performing laparoscopic cholecystectomy. The pathologic acuity of the gallbladders was distributed similarly for all three groups. There was a difference in mean operating time based on pathologic acuity. Laparoscopic cholecystectomy can be performed in a safe and efficient manner at a teaching institution.

Effect of pH and Zn(2+) on subcultured muscle cells from Macrobrachium nipponense.

A cell culture system was devised for muscle cell of Macrobrachium nipponense in the study. The juvenile and adult shrimps were held in laboratory aquaria with penicillin 1000 IU/ml and streptomycin 1000 microg/ml for 12-24 hours. Cell cultures were established in medium 199 supplemented with 20% fetal bovine serum, 1 g/L glucose, 5.2 g/L NaCl, 1.43 g/L CaCl(2), 0.05 g/L MgCl(2), 100 IU/mL penicillin and 100 microg/ml streptomycin. Fibroblast-like cells were passaged up to three times and survived for 54 days. The results showed the optimum for subculture in vitro was in medium 199 with pH 7.6. Moreover, basal medium supplemented with Zn(2+) 60 microg/L could enhance the growth of the muscle cells. It was found that better results for cell culture would be obtained more easily with juvenile shrimps caught in spring than adults in summer or autumn; and shrimps caught within 12 hours after ecdysis could grow much better than the intermoult shrimps.

Bond strength with APF applied after acid etching.

One tenet of successful orthodontic therapy is to complete treatment without decalcification, hypocalcification, or discoloration of the natural dentition. Fluoride application has been shown to reduce demineralization of enamel. The purpose of this study was to see if fluoride could be incorporated into enamel before orthodontic bracketing without adversely affecting bond strength. Forty extract adolescent human premolars were randomly divided into two equal groups with 20 teeth each. Group 1 served as control group, and group 2 (experimental) was immersed in 1.23% acidulated phosphate fluoride for 4 minutes after acid etching. The buccal surfaces of all 40 teeth were then bonded with the same type of metal bracket and debonded with an Instron machine. The debonding interface was observed with scanning electron microscopy (SEM). The mapping was calculated with energy dispersive x-ray spectrometry. The results showed that the bond strength of group 1 was significantly greater than that of group 2. The enamel detachment (enamel fracture) was found in the experimental group only. Although the application of acidulated phosphate fluoride to a tooth can prevent dental decay or decalcification, the bond strength decreases and enamel detachment is found after debonding. The result shows that the application of acidulated phosphate fluoride after acid etching enamel has an adverse effect on orthodontic bond strength of human enamel.

Fluoridated etching on orthodontic bonding.

Enamel demineralization that occurs adjacent to directly bonded orthodontic attachments is of great concern to orthodontists. One procedure suggested to overcome this problem is to use fluoride treatment in an acid etch. The purpose of this study was to evaluate the bond strength and the debonding interface distribution of adhesive, with and without the use of fluoridated etch on enamel, before bonding. Ten teeth were etched with 37% phosphoric acid (H3PO4), incorporated with 1.23% sodium fluoride (NaF) for 15 seconds. The control group of 10 teeth was etched with the 37% H3PO4 solution for 15 seconds without fluoride. Fluoride on enamel was first detected with scanning auger microscribe/photoelectron spectroscopy in the fluoridated etching group. The brackets were then bonded on the labial surfaces of the crowns of both groups of teeth. The bracketed teeth were tested, with an Instron machine, to determine the tensile bond strength, as well as with a scanning electron microscope, and by mapping with an energy dispersive x-ray spectrometer to detect the debonding interfaces. The results showed that the fluoride was found on the enamel after fluoridated etching for 15 seconds. The bond strength and debonding interface distribution between the two groups were not statistically significantly different. Enamel detachment was not present in either group. Hence, the fluoridated etching with 1.23% NaF may have a clinical application in the prevention of demineralization or caries surrounding and under orthodontic brackets bonded to enamel.

Bond strength: a comparison between chemical coated and mechanical interlock bases of ceramic and metal brackets.

Two types of chemically coated bases, two types of mechanical interlock base polycrystalline ceramic brackets, as well as one type of mechanical interlock base metal bracket were selected for bonding with Concise orthodontic resin on 60 extracted premolars. Bond strength was measured with an Instron testing machine and the debonded interface and enamel detachment were examined with scanning electron microscope and energy dispersive x-ray spectrometer. The results showed the greater bond strength with a chemically coated base of ceramic brackets had a greater debonded interface between enamel and resin, and the weaker bond strength of mechanical interlock base of ceramic and metal brackets had a greater debonded interfaces between bracket and resin. There was no significant statistical difference in bond strengths with mechanically interlock bases between ceramic and metal brackets. The enamel detachment was found on only the stronger bond strength in which there was a chemically coated base on the ceramic bracket. Ceramic bracket fractures were not found during debonding in this specially designed specimen with 1 mm/min speed of crosshead. The mechanical interlock base of the ceramic bracket combines the strength, durability and retention of a metal bracket along with an aesthetic advantage and no enamel detachment after debonding.