The role of bacteria and its derived biomaterials in cancer radiotherapy.

Bacteria-mediated anti-tumor therapy has received widespread attention due to its natural tumor-targeting ability and specific immune-activation characteristics. It has made significant progress in breaking the limitations of monotherapy and effectively eradicating tumors, especially when combined with traditional therapy, such as radiotherapy. According to their different biological characteristics, bacteria and their derivatives can not only improve the sensitivity of tumor radiotherapy but also protect normal tissues. Moreover, genetically engineered bacteria and bacteria-based biomaterials have further expanded the scope of their applications in radiotherapy. In this review, we have summarized relevant researches on the application of bacteria and its derivatives in radiotherapy in recent years, expounding that the bacteria, bacterial derivatives and bacteria-based biomaterials can not only directly enhance radiotherapy but also improve the anti-tumor effect by improving the tumor microenvironment (TME) and immune effects. Furthermore, some probiotics can also protect normal tissues and organs such as intestines from radiation via anti-inflammatory, anti-oxidation and apoptosis inhibition. In conclusion, the prospect of bacteria in radiotherapy will be very extensive, but its biological safety and mechanism need to be further evaluated and studied.

An economic evaluation of pit and fissure sealants and fluoride varnishes in preventing dental caries: a systematic review.

The aim was to systematically evaluate the cost-effectiveness of pit and fissure sealants (PFSs) compared with that of fluoride varnishes (FVs) in dental caries prevention. We searched four electronic databases including the Cochrane Oral Health Group's Trials Register (till 03 June 2022), Web of Science (from 1945 to 03 June 2022), PubMed (from 1996 to 03 June 2022), and EMBASE via Ovid (from 1980 to 03 June 2022) to identify the cost and effectiveness of PFSs and FVs in decreasing dental caries incidence. Two researchers independently screened search results, extracted data from the included studies, and conducted the risk of bias assessments. The main characteristics of the included studies were extracted and analyzed. The initial search produced 874 articles. After removing duplicates and full-text review, 19 studies were included. In this study: nine studies were on PFSs comparison with control; five on PFSs comparison with FVs; and five on FVs comparison with control. Regarding the type of economic evaluation (EE), 13 studies conducted cost-effectiveness analysis, five conducted cost-utility analyses, and one conducted both cost-effectiveness analysis and cost-utility analyses. The cost-effectiveness evaluation of PFSs and FVs in the available studies was limited. The prevalence of dental caries, payers' willingness to pay, length of follow-ups, delivery settings, retention rate of PFS, and application intervals of FV can affect the economic evaluation of these two methods for dental caries prevention. Therefore, more studies in the future are need to draw clear conclusions about which method is more cost-effective for the two preventive interventions in future.

68Ga-PSMA-11 PET/CT versus 68Ga-PSMA-11 PET/MRI for the detection of biochemically recurrent prostate cancer: a systematic review and meta-analysis.

Purpose: Our aim was to conduct a meta-analysis and systematic review in order to compare the diagnostic efficacy of 68Ga-PSMA-11 PET/CT and 68Ga-PSMA-11 PET/MRI in patients with biochemically recurrent after radical prostatectomy and biochemically recurrent prostate cancers (BCR) after hybrid RT and RP. Methods: Up until February 2023, we searched PubMed, Embase, and Web of Science for pertinent papers. Studies examining the utility of 68Ga-PSMA-11 PET/CT or PET/MRI as a screening tool for biochemically recurrent prostate cancer were included. To measure heterogeneity, we employed the I2 statistic. In cases of substantial heterogeneity (I2 > 50%), we used the random effect model to produce a forest plot. In other cases, we utilized the fixed model. Furthermore, we assessed the quality of the studies included using the Quality Assessment of Diagnostic Performance Studies (QUADAS-2) method. Results: In total, 37 studies involving 8409 patients were examined. For 68Ga-PSMA-11 PET/CT and 68Ga-PSMA-11 PET/MRI, the combined total detection rate was 0.70 (95% CI: 0.65-0.75) and 0.71 (95% CI:0.67-0.75), respectively. 68Ga-PSMA-11 PET/CT and 68Ga-PSMA-11 PET/MRI did not substantially differ in terms of the overall detection rate for BCR (P = 0.58). The detection rate was unaffected by the PSA values (all P > 0.05). Conclusion: The diagnostic efficacy of 68Ga-PSMA-11 PET/CT appears to be equivalent to that of 68Ga-PSMA-11 PET/MRI in detecting biochemically recurrent prostate cancer. Nonetheless, it should be noted that not all studies have used pathological biopsies as the gold standard. Therefore, additional larger prospective studies are needed to address this issue. Systematic review registration: identifier CRD42023410039.

Laser doppler flowmetry to detect pulp vitality, clinical reference range and coincidence rate for pulpal blood flow in permanent maxillary incisors in Chinese children: a clinical study.

BACKGROUND: A laser doppler flowmetry (LDF) test can reflect the pulp vitality caused by the change in pulp blood flow (PBF). This study aimed to investigate the PBF of the permanent maxillary incisors using LDF and to calculate the clinical reference range and coincidence rate for pulp vitality using PBF as an indicator. METHODS: School-age children (7-12 years) were recruited randomly. A total of 455 children (216 female and 239 male) were included in this study. An additional 395 children (7-12 years) who attended the department due to anterior tooth trauma from October 2015 to February 2018 were included to assess the clinical occurrence rate. The PBF was measured using LDF equipment and an LDF probe. RESULTS: The clinical reference range of PBF values for the permanent maxillary incisors (teeth 11, 12, 21, and 22) in children were from 7 to 14 perfusion units (PU), 11 (6.016; 11.900 PU), 12 (6.677; 14.129 PU), 21 (6.043;11.899 PU), and 22 (6.668; 14.174 PU). There was a statistically significant correlation between PBF and children's age (p < 0.000) without any significant gender discrimination (p = 0.395). For all incisors, for any age group, the PBF detection value of the lateral incisors was significantly higher than that of the central incisors (p < 0.05). The clinical coincidence rate of detecting PBF in the traumatic teeth was 90.42% and the sensitivity and specificity were 36.99% and 99.88%, respectively. CONCLUSIONS: The determination of the PBF clinical reference range and clinical coincidence rate for the permanent maxillary incisors in children using LDF provided a promising theoretical basis for clinical applications.

Inhibitory effects of Stevioside on Streptococcus mutans and Candida albicans dual-species biofilm.

Introduction: Streptococcus mutans is the most prevalent biofilm-forming pathogen in dental caries, while Candida albicans is often detected in the presence of S. mutans. Methods: We aimed to evaluate the anti-caries effect of stevioside in medium trypticase soy broth (TSB) with or without sucrose supplementation compared with the same sweetness sucrose and xylitol in a dual-species model of S. mutans and C. albicans, based on planktonic growth, crystal violet assay, acid production, biofilm structural imaging, confocal laser scanning microscopy, and RNA sequencing. Results: Our results showed that compared with sucrose, stevioside significantly inhibited planktonic growth and acid production, changed the structure of the mixed biofilm, and reduced the viability of biofilm and the production of extracellular polysaccharides in dual-species biofilm. Through RNA-seq, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway impact analysis showed that stevioside decreased sucrose metabolism and increased galactose and intracellular polysaccharide metabolism in S. mutans, and decreased genes related to GPI-modified proteins and secreted aspartyl proteinase (SAP) family in C. albicans. In contrast to xylitol, stevioside also inhibited the transformation of fungal morphology of C. albicans, which did not form mycelia and thus had reduced pathogenicity. Stevioside revealed a superior suppression of dual-species biofilm formation compared to sucrose and a similar anti-caries effect with xylitol. However, sucrose supplementation diminished the suppression of stevioside on S. mutans and C. albicans. Conclusions: Our study is the first to confirm that stevioside has anticariogenic effects on S. mutans and C. albicans in a dual-species biofilm. As a substitute for sucrose, it may help reduce the risk of developing dental caries.

[Comparison of dentinal microcracks caused by new generation of single reciprocating files after root canal preparation].

PURPOSE: To compare the incidence of dentinal microcracks after root canal preparation by new generation of nickel-titanium instrument WaveOne Gold, Reciproc Blue with previous WaveOne and Reciproc. METHODS: Ninety extracted single-rooted mandibular premolars were randomly divided into 6 groups(n=15). The root canals were instrumented by using Hand K files, WaveOne, Reciproc, WaveOne Gold and Reciproc Blue. Fifteen teeth were left unprepared and served as negative controls. The root canals were all prepared to 25#. The roots were then sectioned at 3 mm, 6 mm and 9 mm from the apical orifice using a hard tissue slicer. The slices were observed under stereoscopic microscope at ×25 magnification. SPSS 17.0 software package was used for statistical analysis. RESULTS: No dentinal microcrack was found in the hand K files group and negative control group. The reciprocating single files WaveOne, WaveOne Gold, Reciproc and Reciproc Blue all produced dentinal microcracks after root canal preparation. The WaveOne generated the most dentinal microcracks than the hand K files(P＜0.05), and the microcracks were mainly concentrated in the middle part of the root. The number of dentinal microcracks caused by Reciproc and Reciproc Blue was the same, with no significant difference(P＞0.05). CONCLUSIONS: The new generation of reciprocating files of WaveOne Gold and Reciproc Blue may not increase the incidence of dentinal microcracks after root canal preparation.

Polydopamine-Coated Radiolabeled Microspheres for Combinatorial Radioembolization and Photothermal Cancer Therapy.

Transarterial radioembolization (TARE) is a local radionuclide therapy and is successfully used in hepatocellular carcinoma (HCC) treatment. Radioactive microspheres have been widely studied for TARE. Preparation of ideal radioactive microspheres is significant for clinical research and patient treatment. In this study, we have designed a novel multifunctional microsphere, i.e., polydopamine (PDA)-coated 177Lu-radiolabeled silica microspheres (MS) denoted as 177Lu-MS@PDA, which can be used for TARE and photothermal therapy (PTT). The radiostability of 177Lu-MS@PDA was significantly improved by coating 177Lu-MS with PDA. In addition, the coating of PDA makes microspheres have excellent photothermal performance. MicroSPECT/CT images showed that 177Lu-MS@PDA was accurately embolized and remained in the tumor during the observation time. At the time, it also showed that 177Lu-MS@PDA was very stable in vivo. Furthermore, the anti-tumor results demonstrated that TARE combined with PTT of 177Lu-MS@PDA can significantly inhibit tumor growth without obvious side effects. 177Lu-MS@PDA holds great potential as a promising radioactive microsphere for HCC.

Utilization of dental care service and associated factors among pre-school children in northwest China over the past decade.

OBJECTIVE: The purpose of this study was to analyze the factors influencing the utilization of oral health care among 5 years old children. METHODS: We conducted two observational cross-sectional studies. The studies were conducted in 2005 and 2015 and included 5-year-old children who underwent dental examination by trained dentists and the caregivers of the children were requested to answer the questionnaire. Multi-level stratified sampling method was used. Chi-square tests were used to analyze the utilization of dental care and other socio-economic variables. Logistic regression models were employed to explore the primary factors influencing the use of dental care among pre-school children. RESULTS: In 2005, a total of 399 and in 2015, 492 child-caregiver pairs were included. The majority of the caregivers in both surveys were females, comprising 68.2% and 74.8% of the caregivers in 2005 and 2015, respectively. 75.2% and 87.0% (p < 0.05) of the respondents had an education level of lesser than 9 years. The prevalence of caries was higher in 2015 (63.2%) (p < 0.05) than in 2005 (53.4%). In 2005 and 2015, the utilization of dental care services was 20.8% and 20.0%, respectively. A statistically significant association was observed between caries and dental care use in 5-year-olds over the past decade. After adjusting for confounders, dental service usage among children in urban areas was 1.62 times higher than that of rural areas in 2005 (95% CI 0.069-0.571), and the self-assessment of caregivers regarding their child's oral health significantly improved oral health use in 2015. CONCLUSION: The utilization of dental care services over the past decade is insufficient among pre-school children in northwest China. Hence, with the decreasing gap about economic and health service resources, policymakers should place greater emphasis on raising awareness among caregivers about the oral health status of their children.

Novel antimicrobial agents targeting the Streptococcus mutans biofilms discovery through computer technology.

Dental caries is one of the most prevalent and costly biofilm-associated infectious diseases worldwide. Streptococcus mutans (S. mutans) is well recognized as the major causative factor of dental caries due to its acidogenicity, aciduricity and extracellular polymeric substances (EPSs) synthesis ability. The EPSs have been considered as a virulent factor of cariogenic biofilm, which enhance biofilms resistance to antimicrobial agents and virulence compared with planktonic bacterial cells. The traditional anti-caries therapies, such as chlorhexidine and antibiotics are characterized by side-effects and drug resistance. With the development of computer technology, several novel approaches are being used to synthesize or discover antimicrobial agents. In this mini review, we summarized the novel antimicrobial agents targeting the S. mutans biofilms discovery through computer technology. Drug repurposing of small molecules expands the original medical indications and lowers drug development costs and risks. The computer-aided drug design (CADD) has been used for identifying compounds with optimal interactions with the target via silico screening and computational methods. The synthetic antimicrobial peptides (AMPs) based on the rational design, computational design or high-throughput screening have shown increased selectivity for both single- and multi-species biofilms. These methods provide potential therapeutic agents to promote targeted control of the oral microbial biofilms in the near future.

Synergistic Function between Phosphorus-Containing Flame Retardant and Multi-Walled Carbon Nanotubes towards Fire Safe Polystyrene Composites with Enhanced Electromagnetic Interference Shielding.

As a universal polymer material, polystyrene (PS) is widely applied in electrical devices and construction. Thus, it is necessary to improve the flame retardancy and electromagnetic shielding properties of PS material. In this work, PS/silicon-wrapped ammonium polyphosphate/Inorganic acid-treated multi-walled carbon nanotubes composites (PS/SiAPP/aMWCNT, abbreviated as PAC) were prepared via methods of filtration-induced assembly and hot-pressing. Morphology and structure characterization demonstrated that SiAPP and aMWCNT had good dispersion in PS and excellent compatibility with the PS matrix. Thermogravimetric analysis revealed that the addition of aMWCNT to PS improved its thermal stability and carbon-forming characteristics. The peak heat release rate, the peak carbon monoxide production rate, and the peak smoke production rate of the PAC10 composite decreased by 53.7%, 41.9%, and 45.5%, respectively, while its electromagnetic shielding effectiveness reached 12 dB. These enhancements were attributed to the reason that SiAPP and aMWCNT synergistically catalyzed the char generation and SiAPP produced free radical scavengers and numbers of incombustible gases, which could decrease the oxygen concentration and retard the combustion reaction. Therefore, the assembled PS/SiAPP/aMWCNT system provides a new pathway to improve the flame retardant and electromagnetic shielding properties of PS.

An in situ micro-indentation apparatus for investigating mechanical parameters of thermal barrier coatings under temperature gradient.

Premature failure of thermal barrier coatings (TBCs) under a temperature gradient is an overriding concern in many applications, and their mechanical parameters are essential to failure analysis. In this study, an in situ micro-indentation apparatus, including a heating module, cooling module, and micro-indentation module, was developed to study the mechanical parameters of TBCs with a temperature gradient. The upper surface of the TBC was heated by radiation to simulate high-temperature service conditions, and the bottom surface was gas-cooled. Different temperature gradients are obtained by changing the velocity of the cooling gas. The temperatures through the thickness of the TBCs were analyzed by numerical simulations and experiments. During exposure to the temperature gradient, micro-indentation tests of the TBC samples were conducted to obtain their mechanical parameters. In situ micro-indentation tests at different cooling gas flow rates (0, 20, and 40 l/min) were performed on the TBCs. The elastic modulus and stress evolution of the TBCs were extracted by analyzing the load-displacement curves at different gas velocities. The elastic modulus remains almost constant with increasing velocity while the stress difference increases.

Calcium mitigates fluoride-induced kallikrein 4 inhibition via PERK/eIF2α/ATF4/CHOP endoplasmic reticulum stress pathway in ameloblast-lineage cells.

OBJECTIVES: The present study aimed to investigated the effect and mechanism of Ca2+ treatment on fluoride in ameloblast-lineage cells (ALCs). MATERIALS AND METHODS: The effects of fluoride and different Ca2+ levels treatment on the proliferative activity, cell apoptosis, cell cycle, intracellular free Ca2+, were firstly determined. Kallikrein 4 (KLK4), glucose-responsive protein 78 (GRP78), Protein kinase R -like endoplasmic reticulum kinase (PERK), the α subunit of eukaryotic initiation factor 2 (eIF2α), activating transcription factor 4 (ATF4), CCAAT enhancer-binding protein homologous protein (CHOP), were investigated in ALCs. RESULTS: The proliferative activity was obviously inhibited under concentrations of single fluoride high than 1 mM, and indicated highest proliferation at single 2.5 mM Ca2+ concentration in ALC cells. In addition, we found that single fluoride markedly induced intracellular free Ca2+ increasing, G2/M phase arrest, apoptosis. GRP78 and endoplasmic reticulum stress pathway of PERK/eIF2α/ATF4/CHOP were significantly increased, while the proliferation and KLK4 were markedly reduced in ALCs. Ca2+ additional treatment can obviously reverse the effect of fluoride-induced apoptosis and inhibition of KLK4. The effect of GRP78 and endoplasmic reticulum stress pathway of PERK/eIF2α/ATF4/CHOP were also alleviated under Ca2+ additional treatment in ALCs. More important, the results of 2.5 mmol/L Ca2+ treatment on the proliferation, cell cycle and apoptosis suggest this concentration is relatively better to mediate the intracellular Ca2+ homeostasis in ALCs. CONCLUSIONS: In sum, Ca2+-supplementation exerts antagonistic the toxic effects on fluoride and this inhibitory effect suggests the potential implications for Ca2+-supplementation on fluorosis.

HIV testing behaviors and willingness to receive oral rapid HIV testing among dental patients in Xi'an, China.

INTRODUCTION: HIV testing is an important strategy for controlling and ultimately ending the global pandemic. Oral rapid HIV testing (ORHT) is an evidence-based strategy and the evidence-based shows is favored over traditional blood tests in many key populations. The dental setting has been found to be a trusted, convenient, and yet untapped venue to conduct ORHT. This study assessed the HIV testing behaviors and willingness to receive ORHT among dental patients in Xi'an, China. METHODS: A cross-sectional survey of dental patients from Xi'an was conducted from August to September 2017. Dental patients were recruited using a stratified cluster sampling. A 44-item survey was used to measure HIV/AIDS knowledge, HIV testing behaviors, and willingness to receive ORHT. RESULTS: Nine hundred and nine dental patients completed the survey with a mean HIV/AIDS knowledge score of 10.7/15 (SD 2.8). Eighty-four participants (9.2%) had previously received an HIV test. Participants would have a high rate of HIV testing if they had higher monthly income (OR = 1.982, 95% CI: 1.251-3.140) and a higher HIV/AIDS knowledge score (OR = 1.137, 95% CI: 1.032-1.252). Five hundred and eighty-two participants (64.0%) were willing to receive ORHT before a dental treatment, 198 (21.8%) were not sure, and 129 (14.2%) were unwilling. Logistic regression showed that age (OR = 0.970, 95% CI: 0.959-0.982), HIV/AIDS knowledge score (OR = 1.087, 95% CI: 1.031-1.145), previous HIV test (OR = 2.057, 95% CI: 1.136-3.723), having advanced HIV testing knowledge (OR = 1.570, 95% CI: 1.158-2.128), and having advanced ORHT knowledge (OR = 2.074, 95%: CI 1.469-2.928) were the factors affecting the willingness to receive ORHT. CONCLUSIONS: The majority of dental patients had not previously received an HIV test, although many were receptive to being tested in the dental setting. The dental setting as a venue to screen people for HIV needs further exploration, particularly because many people do not associate dentistry with chairside screenings. Increasing awareness of ORHT and reducing testing price can further improve the patient's willingness to receive ORHT.

MAP kinase phosphatase MKP-1 regulates p-ERK1/2 signaling pathway with fluoride treatment.

Dental fluorosis is characterized by hypomineralization of tooth enamel caused by ingestion of excessive fluoride during enamel formation. Excess fluoride could have effects on the ERK signaling, which is essential for the ameloblasts differentiation and tooth development. MAP kinase phosphatase-1 (MKP-1) plays a critical role in regulating ERK related kinases. However, the role of MKP-1 in ameloblast and the mechanisms of MKP-1/ERK signaling in the pathogenesis of dental fluorosis are incompletely understood. Here, we adopted an in vitro fluorosis cell model using murine ameloblasts-like LS8 cells by employing sodium fluoride (NaF) as inducer. Using this system, we demonstrated that fluoride exposure led to an inhibition of p-MEK and p-ERK1/2 with a subsequent increase in MKP-1 expression in a dose-dependent manner. We further identified, under high dose fluoride, MKP-1 acted as a negative regulator of the fluoride-induced p-ERK1/2 signaling, leading to downregulation of CREB, c-myc, and Elk-1. Our results identify a novel MKP-1/ERK signaling mechanism that regulates dental fluorosis and provide a framework for studying the molecular mechanisms of intervention and fluorosis remodeling under normal and pathological conditions. MKP-1 inhibitors may prove to be a benefit therapeutic strategy for dental fluorosis treatment.

Pellino-1 Protects Periodontal Ligament Stem Cells Against H2O2-Induced Apoptosis via Activation of NF-κB Signaling.

To determine the protective effects of Pellino-1 against H2O2-induced apoptosis in periodontal ligament stem cells (PDLSC). We demonstrated that H2O2 decreases PDLSC viability by 40 and 50% with the concentrations of 400 and 500 µM, respectively, with an observed downregulation of Pellino-1 mRNA and protein; we further concluded that overexpression of Pellino-1 significantly lowers 8-hydroxy-2'-deoxyguanosine levels by 10% and upregulates superoxide dismutase 1, glutathione peroxidase levels, and catalase mRNA levels by 200, 40, and 250%, respectively. More importantly, we found that overexpression of Pellino-1 inhibited H2O2-induced cellular apoptosis through the activation of the NF-κB signaling pathway. Pellino-1 may be critically important for cell survival in the presence of oxidative elements; activation of the NF-κB signaling cascade was required for the overexpression of Pellino-1 to protect the cells from H2O2-induced apoptosis.

[Effects of fluoride on expression of survivin during rats' dental germ development].

PURPOSE: This study was to investigate the expression of survivin in dental germ development of SD rats with fluorosis, and explore the effects of fluoride on survivin expression and the pathogenic mechanism of dental fluorosis. METHODS: Forty-five SD rats (pregnant for 10 days) were randomly divided into control group, experimental group 1 and group 2. Drinking water with fluoride concentration of 0, 50, 150 mg/L was provided for rats accordingly. The samples were collected at E18.5th day, E20.5th day, P1.5th day, P3.5th day and P5.5th day, then the samples of P1.5th day were selected for H-E staining. SABC method was used for immunohistochemical analysis of samples in each group. The images were acquired by Motic Med 6.0 digital medical image analysis system, and the data were analyzed for ANOVA with SPSS 13.0 software package. RESULTS: Survivin expression fluctuated and exhibited 'M' shape (rose first and fell later) in each group.There was no significant difference at E18.5th day (F=1.050, P>0.05) and E20.5th day (F=2.232, P>0.05) between each group. There were significant differences at P1.5th day (F=3.538, P<0.05), P 3.5th day (F=3.820, P<0.05) and P5.5th day (F=5.096, P<0.05) between the control and experimental groups. The postnatal rats in each group were evaluated by SNK method for surviving expression. There was no significant difference between control group and experimental group 1 (P>0.05). However, there was significant difference between control group and experimental group 2 (P<0.05). CONCLUSIONS: The results suggest that fluoride can decrease the expression of survivin in the postnatal rats with higher fluoride concentration, which may be the mechanism in the development of dental fluorosis.

Light enhanced energy storage ability through a hybrid plasmonic Ag nanowire decorated hydroxide "skin structure".

By decorating nickel copper hydroxide (NCH) with Ag nanowires (Ag NWs), a 1.7 fold enhancement in areal capacitance (5.4 F cm-2) and a 1.8 fold increment in gravimetric capacitance (3182 F g-1) under light illumination were achieved. The improved supercapacitor performances of the composites under visible-light illumination were demonstrated and a reasonable explanation for this newly-discovered phenomenon was proposed. The plasmonic effect of Ag NWs was demonstrated by hot-electron generation. The decorated Ag NWs served as a stimulus for redox reactions. This research provides a tantalizing opportunity for enhancing the supercapacitor performance by exploiting surface plasmon metals. The finding from this study will be informative for the future design of supercapacitor electrodes.

Quality of Life in Patients After Maxillectomy and Placement of Prosthetic Obturator.

PURPOSE: The aim of this study was to assess quality of life (QoL) and obturator functioning in patients having undergone a maxillectomy as a tumor ablative resection and rehabilitation with a prosthetic obturator. MATERIALS AND METHODS: The University of Washington Quality of Life scale version 4 (UW-QoLv4) and the Obturator Functioning Scale (OFS) were used to evaluate the self-reported QoL and obturator functioning. The effects of demographic and treatment variables on QoL were assessed using age, defect size, postoperative radiotherapy (RT), neck dissection, and dentition. RESULTS: The study included 16 men and 13 women with a mean age of 48.8 years. Of the 29 patients, 16 had a Brown Class 2a or smaller defect and 13 had a Brown Class 2b or larger defect. The mean OFS score (P = .004) and the physical (P = .001) and social-emotional function scores (P = .001) of the patients who received postoperative RT were significantly lower than those who did not receive postoperative RT. The subscales for swallowing (P = .008), saliva (P = .001), pain (P = .001), and shoulder function (P = .002) correlated strongly with postoperative RT on the UW-QoL. The subscales for pronunciation (P = .007) and saliva (P = .002) correlated significantly with RT on the OFS. The mean OFS scores were significantly lower for the patients with a Brown Class 2a or smaller defect than for Brown Class 2b or larger (P = .005). CONCLUSION: Postoperative RT was the strongest variable affecting QoL in patients with maxillectomy and prosthetic obturator reconstruction. The size of the defect slightly influenced the obturator function; however, it did not influence the overall QoL.

[Effect of topical iron, fluoride application on eroded enamel in vitro].

PURPOSE: To evaluate the effect of supplementation containing iron and/or fluoride on eroded enamel in vitro. METHODS: Eighty enamel specimens collected in orthodontic treatments were randomly allocated into 4 groups of 20 samples each: C (control,deionized water); Fe(2+)(15 mmol/L FeSO(4)); F(-)(1.23% NaF) and Fe(2+)+ F(-)(15 mmol/L FeSO(4) and 1.23% NaF ). Before all samples submitted to 6 alternating demineralization and remineralization cycles, they were pre-treated with one of the experimental solutions for 1 minute. One complete cycle consisted of the following steps: ①demineralization in 5 mL beverage (Coca-Cola, pH=2.58) for 5 minutes under gentle agitation; ②remineralization in 5 mL artificial saliva for 1 hour at 37°C. The effect of erosion was observed by enamel surface morphology and measured by superficial micro-hardness (SMH). One-way ANOVA was performed using SPSS18.0 software package for analysis of the data. RESULTS: The SMH of enamel after erosion by carbonated drinks was significantly lower than the SMH before erosion. When ferrous sulfate with or without fluoride was tested for the prevention of enamel demineralization, there was statistically significant increase in the SMH of enamel in comparison with the control (P<0.001). However, the experimental solutions did not differ significantly among them. Scanning election microscope showed the deposition on the enamel surface after iron or fluorine treatment ,and the damage degree of the enamel surface were reduced compared with the control. CONCLUSIONS: Iron and/or fluoride was shown to be effective to enhance the acid resistance of enamel,while the combined use of fluoride and iron in group Fe(2+)+F(-)had no cumulative effects.

[Study on enhancement effect and mechanism of the acid resistance of enamel by Fe2+ and F].

PURPOSE: The phase of new substances and the effect on enamel lattice was analysed after ferrous sulfate ,sodium fluoride treatment through X-ray diffraction, in order to explore the mechanism of Fe2+ and F- reinforced enamel acid resistance. METHODS: Fragments of enamel obtained from fifty molars were ground into powder and randomly divided into four groups: C (control,deionized water); Fe2+ (15 mmol/L FeSO4); F- (1.23% NaF) and Fe2++F- (15 mmol/L FeSO4 and 1.23% NaF). Before exposure to acid, the samples were incubated in one of the experimental solutions for 48 hours. After that, the samples were submitted to six alternating remineralization and demineralization cycles. A complete cycle consisted of the following steps:① demineralization in 5 mL of the beverage (Coca-Cola, pH=2.58) for 5 minutes under gentle agitation;② remineralization in 5 mL of artificial saliva for 1 hour at 37℃. X-ray diffraction was employed to identify precipitates and estimate their lattice constants before enamel power dried at 40℃. RESULTS: The XRD pattern of the group of ferrous sulfate was not sharper than control while the full width half maximum of peak increased and became more gentle. The enamel crystal grain size and crystallinity decreased. Secondary phase retrieval showed there was new phase formed which was iron phosphate. Diffraction spectrum of ferrous sulfate with fluoride group was similar to fluoride alone, the full width half maximum of peak became sharper and more narrow.The enamel crystal grain crystallinity improved and there was new phase of calcium fluoride formed. CONCLUSIONS: Fe2+ and F- both had certain influence on the crystal structure of enamel. However, the impact of Fe2+ was concealed when reacted with high concentration F-. Fe2+ may participate in the nucleation of apatite through substitution of calcium in apatite. Acid-resistant enamel surfaces are established due to precipitation of ferric phosphates on the enamel surface, and combination of Fe2+ with PO4(3-) dissolved on enamel surface. F- may participate in the nucleation of apatite through substitution of OH-; at the same time, the calcium fluoride precipitation was established.