Progress and perspectives on cell-free regenerative endodontic therapy.

Although teeth with pulpitis/apical periodontitis are saved after successful endodontic therapy, they are devitalized and susceptible to reinfections and fractures. The development of biology-based approaches for dental pulp regeneration or repair is possible today because of recent advances in tissue engineering and biomaterials. Cell-free regenerative endodontic therapy offers a promising strategy for the treatment of necrotic immature permanent teeth in children and adolescents. However, studies are underway to determine whether this procedure can be applied to mature teeth.

Noble Metal-Free FeOOH/Li0.1WO3 Core-Shell Nanorods for Selective Oxidation of Methane to Methanol with Visible-NIR Light.

Hydroxyl radicals (•OH) generated in the photocatalytic process are crucial to the conversion of methane (CH4) to value-added methanol (CH3OH) at room temperature. However, utilizing noble metal-free catalysts and low-energy photons of solar light, such as visible and near-infrared light (vis-NIR), is difficult to provide more electron states to form •OH radicals. Here, we developed FeOOH/Li0.1WO3 core-shell nanorods via a two-step in/out co-modification of hexagonal tungsten oxide (h-WO3): (1) lithium ions intercalating into the hexagonal tunnels of h-WO3 to form Li0.1WO3 nanorods and (2) using FeOOH-wrapped Li0.1WO3 to obtain FeOOH/Li0.1WO3 core-shell nanorods. Introduction of lithium induces polaron transition in Li0.1WO3, enabling the absorption of vis-NIR light. Interestingly, FeOOH-based Fenton-like reaction when H2O2 is selected as an oxidant favors the generation of more •OH radicals available for CH4 oxidation to CH3OH. Meanwhile, FeOOH with FeIII as an "electron sink" highly improves the separation of photoinduced electrons and holes in Li0.1WO3. Eventually, efficient selective formation of CH4OH is achieved with remarkable generation rates up to ∼342 and ∼160 µmol g-1 at visible light (420-700 nm) and NIR light (≥800 nm), respectively. Our finding opens up new possibilities for developing noble metal-free catalysts for solar energy-driven CH4 conversion to CH3OH under ambient conditions.

Fabrication and Properties of a Free-Standing Two-Dimensional Titania.

The synthesis of free-standing two-dimensional titania (2-D TiO2) with a reduced band gap presents complex challenges to synthetic chemists. Here, we report a free-standing 2-D TiO2 sheet synthesized via a one-step solvothermal methodology, with a measured optical onset at ∼1.84 eV. Using first-principles calculations in combination with experiment, we propose that the as-formed 2-D TiO2 sheets are layers of the lepidocrocite TiO2 structure, but with large nonuniform strains consistent with its crumpled morphology. These strains cause a significant change in the quasiparticle band structure and optical absorption spectra, resulting in large absorption in the visible-light region. This narrow band gap 2-D TiO2 can catalyze the formation of singlet oxygen and the degradation of dye pollutants with low-energy photons of solar light. Our work demonstrates that lattice strains intrinsic to 2-D materials, especially its crumpled, free-standing forms, can result in new and useful properties.

Visible-Near-Infrared-Light-Driven Oxygen Evolution Reaction with Noble-Metal-Free WO2-WO3 Hybrid Nanorods.

Understanding and manipulating the one half-reaction of photoinduced hole-oxidation to oxygen are of fundamental importance to design and develop an efficient water-splitting process. To date, extensive studies on oxygen evolution from water splitting have focused on visible-light harvesting. However, capturing low-energy photons for oxygen evolution, such as near-infrared (NIR) light, is challenging and not well-understood. This report presents new insights into photocatalytic water oxidation using visible and NIR light. WO2-WO3 hybrid nanorods were in situ fabricated using a wet-chemistry route. The presence of metallic WO2 strengthens light absorption and promotes the charge-carrier separation of WO3. The efficiency of the oxygen evolution reaction over noble-metal-free WO2-WO3 hybrids was found to be significantly promoted. More importantly, NIR light (≥700 nm) can be effectively trapped to cause the photocatalytic water oxidation reaction. The oxygen evolution rates are even up to around 220 (λ = 700 nm) and 200 (λ = 800 nm) mmol g-1 h-1. These results demonstrate that the WO2-WO3 material is highly active for water oxidation with low-energy photons and opens new opportunities for multichannel solar energy conversion.

Gene transfer-mediated functional restoration for irradiated salivary glands.

Radiation therapy for malignant tumours in the head and neck region are inevitably associated with significant long-term injury to the salivary glands, often resulting in salivary gland hypofunction. The subsequent lack of saliva production leads to many functional and quality-of-life problems for affected patients and there is no effective method to eliminating this problem caused by radiation treatments. Although many studies have been done in animal models, the mechanism of this injury in humans is still unclear. In this review, an animal model (miniature pigs) used in irradiated research is mainly discussed. This review also presents the progress made to date on the gene transfer-mediated functional restoration of irradiated salivary glands and the possibilities provided by future interventions to prevent radiation damage to salivary glands.

[Increase of saliva nitrate and nitrite level in patients with oral candidiasis].

OBJECTIVE: To observe the alterations of saliva nitrate and nitrite level in patients with oral candidiasis. METHODS: Parotid saliva and whole saliva were collected from 33 patients and 34 healthy volunteers. Concentrations of nitrate and nitrite in saliva were determined by high-performance liquid chromatography. Follow-up observation was performed on 10 patients after treatment. The data were statistically analyzed with independent-samples t test or paired-samples t test at alpha = 0.05. RESULTS: There was significant increase of the concentrations and secretion rate of parotid saliva nitrate in patient group as compared with controls: (49.70 +/- 0.50) vs (21.51 +/- 0.60) mg/L (t = 2.692, P = 0.009) and (27.71 +/- 0.50) vs (12.55 +/- 0.60) microg/min (t = 2.554, P = 0.013), respectively. Significantly increased concentrations and secretion rate of nitrate and nitrite [nitrate: (6.46 +/- 0.94) vs (1.11 +/- 0.70) mg/L (t = 3.792, P = 0.000); nitrite: (8.48 +/- 0.58) vs (3.39 +/- 0.53) mg/L (t = 2.888, P = 0.005); nitrate secretion rate: (10.57 +/- 0.91) vs (2.10 +/- 0.74) microg/min (t = 3.464, P= 0.001); nitrite secretion rate: (13.91 +/- 0.55) vs (6.42 +/- 0.58) microg/min (t = 2.397, P = 0.020)] were revealed in whole saliva of patients group. Significantly decreased nitrate and nitrite levels were also observed in patients after treatment, especially the changes of parotid saliva nitrate secretion rate [(37.50 +/- 0.50) vs (14.34 +/- 0.64) microg/min (t = 3.142, P = 0.012)], whole saliva nitrate [(14.29 +/- 1.01) vs (2.59 +/- 1.03) mg/L (t = 3.475, P = 0.007)] and whole saliva nitrate secretion rate [(25.97 +/- 0.93) vs (4.12 +/- 1.00) microg/min (t = 3.922, P = 0.003)]. CONCLUSION: The present study revealed the significant increase of salivary nitrate and nitrite level in patients with oral candidiasis is considered to be associated with the host defense reaction.

[Comparative ultrastructural study of parotid gland, lacrimal gland and pituitary gland between miniature pig and mouse].

OBJECTIVE: To study the ultrastructure of parotid glands, lacrimal glands and pituitary glands between miniature pig and mouse. METHODS: Five adult miniature pigs and 5 mice were studied. Ultrastructure of their parotid glands, lacrimal glands, and pituitary glands was observed. RESULTS: The secretary granules in acinar cell of miniature pig parotid glands showed higher density and more aequalis than those of mice. The cell apparatus in acinar cell of mouse parotid glands were more plentiful than those of miniature pigs. The secretary granules on blood vessel wall were richer in parotid gland of miniature pigs compared with mouse parotid gland. Lacrimal gland had the similar ultrastructure to parotid gland in these two animals. Many blood vessel antrum were found in pituitary glands of these two animals. CONCLUSIONS: Compared with mouse parotid glands, there are more secretary granules in acinar cells and vascular endothelial cells in miniature pig parotid glands, which might enter blood stream and have function of endocrine secretion.

[Tooth regeneration--dream to reality].

Tooth or dentition missing compromises human health physically and psychiatrically. Although several prosthesis methods are used to restore tooth loss, these restorations are still non-biological methods. It is a dream for human being to regenerate a real tooth for hundreds years. There are two ways to regenerate the tooth. One is application of conventional tissue engineering techniques including seed cells and scaffold. The other is regeneration tooth using dental epithelium and dental mesenchymal cells based on the knowledge of tooth initiation and development. Marked progress has been achieved in these two ways, while there is still a long way to go. Recently a new concept has been proposed for regeneration of a biological tooth root based on tooth-related stem cells and tissue engineering technique. A biological tooth root has been regenerated in swine. It may be a valuable method for restoration of tooth loss before successful whole tooth regeneration. A latest research showed that a subpopulation in bone marrow cells can give rise to ameloblast-like cells when mixed with embryonic epithelium and reassociation with integrated mesenchyme, which may provide a new seed cell source for tooth regeneration.

[Alterations of salivary flow rate and oral main pathogens in miniature pig with bilateral parotid gland atrophy].

OBJECTIVE: To observe the effect of bilateral parotid gland atrophy on the whole saliva flow rate and the growth of main oral pathogens in different sites of oral cavity. METHODS: Ten healthy miniature pigs were divided into two groups. The parotid glands of test group (n = 5) were bilaterally ablated by methyl violet. Another healthy five miniature pigs served as the control group. Whole saliva was collected and the whole saliva flow rate detected in both groups at 12 and 24 months respectively after parotid atrophy. The total numbers of oral main pathogens in the first molar, cuspid sub-gingival bacteria plaque and whole saliva were also detected. RESULTS: The whole saliva flow rate was significantly decreased at both 12 and 24 months respectively after atrophy of bilateral parotid gland in miniature pig. Pathogens including Streptococcus mutans, Porphyromonas gingivalis and Fusobacterium nucleatum in different sites oral cavity were increased after bilateral parotid gland atrophy. CONCLUSIONS: Bilateral ablation of the parotid glands led to a significant decrease of whole saliva flow rate. The total numbers of main oral pathogens were increased in different sites of oral cavity.

[Preparation and identification of the rabbit antibody against human sialin].

AIM: To prepare the rabbit antibody against human sialin and identify its properties. METHODS: Recombinant expression vector pGEX-5X-1-sialin was constructed, in which the sialin cDNA encoding the 1-38 aa was fused to the C-terminal of the gene encoding the GST protein. The GST-sialin (N1-38) fusion protein was expressed in E. coli JM109 at 37 degrees C in the presence of IPTG at 0.1 mmol/L for induction for 3 hours, purified by GSTrap FF, and then used as the immunogen to prepare the rabbit polyclonal antibody. The properties of antiserum against human sialin were identified by ELISA, Western blot and immunocytochemistry. RESULTS: The recombinant expression plasmid pGEX-5X-1-sialin was constructed. The GST-sialin (N1-38) fusion protein was highly expressed with a molecular weight of 30 kDa, and the yield of the fusion protein was about 20% to 30% in total E. coli protein. The titre of antiserum against human sialin was 1:32,000. Western blot analysis proved the rabbit polyclonal antibody could identify both GST-sialin (N1-38) fusion protein and GST. Besides, it specially recognized a 55 kDa band expressed in the human submandibular gland (HSG) cell line. The antigen recognized by the antibody was located in the cytoplasm and nucleus of HSG cell. CONCLUSION: The successful preparation of the polyclonal antibody against human sialin will provide efficient affinity reagent for further functional study of sialin expressed in human salivary glands.

[Effect of single dose irradiation to parotid gland on the structured and function changes of bilateral parotid glands in miniature pig].

OBJECTIVE: To evaluate the effects of a solitary megadose protocol of ionizing radiation (IR) to parotid gland on the structured and function changes of bilateral parotid glands in miniature pig. METHODS: Fourteen minipigs were subjected to either 15 or 20 Gy to one parotid gland with a linear accelerator, while another four minipigs served as non-IR controls. Salivary flow rates and salivary chemistries were measured pre-IR, and 4 and 16 weeks post-IR. A quantitative assessment of gland weight and acinar area, and detailed serum chemistry and hematological analyses, were also performed. RESULTS: Parotid gland weights were significantly decreased in the 15 and 20 Gy groups at 4 and 16 weeks post-IR. The acinar cell area in glands of both IR groups was significantly reduced. Parotid flow rates decreased by 60% with 15 Gy at 16 weeks post-IR. In the 20 Gy group, salivary flow rates were reduced by 80% at 16 weeks post-IR. Additionally, parotid flow rates significantly reduced in contralateral glands with 20 Gy at 16 weeks, while structure and weight did not changes in parotid glands. CONCLUSION: Structural changes in salivary gland parenchyma occurred relatively early after IR, while the alterations in salivary output were relatively delayed. Further, reductions in salivary flow were not proportional to acinar cell area loss. There isn't a significant structured change of contralateral glands, but significant reduction of parotid flow rate at this time.

[Sialographic, sialoendoscopic and irrigation fluid study in chronic obstructive parotitis].

OBJECTIVE: To study the sialographic changes and to compare the changes with sialoendoscopic and irrigation fluid findings in chronic obstructive parotitis (COP). METHODS: This study involved 27 patients with a long history of parotid swelling. All patients were examined by X-ray, sialography, and were diagnosed as COP without sialolithiasis. Sialoendoscopy was used to observe the ductal system and irrigation treatment performed. The irrigated liquid was centrifuged and the deposits of fluid were stained and observed under microscopy. The sialographic changes were classified as previous studies and compared with sialoendoscopic and irrigation fluid findings. RESULTS: The sialographic changes of COP in 27 patients included 9 cases with type I, 5 cases with type II, 9 cases with type III and 3 cases with type IV changes, 1 case was normal. Marked obstructive factors such as stricture of ductal system were revealed in 21 cases on the sialogram. Sialoendoscopic examination showed that the ductal system was filled with fiber-like substances and hyperaemia of ductal wall in all cases. While few and thin fiber-like substances were found in the COP with sialographic type I and type II changes, many thick wadding or mass fiber-like substances were revealed in COP with sialographic type III and IV changes. Microstones were found in 2 COP with sialographic type III changes which were stained and identified by microscopy. Foreign body (drug bar) was found in one COP with sialographic type I changes with sialoendoscopy. Irrigation fluid examination showed fiber-like substance was composed of desquamative duct epithelial cells, neutrophil, lymphocytes, acidophile. Some epithelial cells were found in two microliths. CONCLUSIONS: The pathological basis of fiber-like substance on sialoendoscopy is desquamative duct epithelial cells. Fiber-like substance in the lumen of ductal system is considered as one of the obstructive factors in COP. Sialoendoscopic findings is related to sialographic changes.

Morphological characteristics of submandibular glands of miniature pig.

BACKGROUND: Miniature pig (minipig) is increasingly used as a large animal model for a variety of biomedical studies. Little information is available in the literature on anatomy, histology and sialograghy of the submandibular gland of the minipig. The purpose of this study was to characterize the morphology of a miniature pig's (minipig) submandibular gland as a large animal model for further biomedical studies. METHODS: Five minipigs were subjected to sialographic, anatomic, histologic, histochemical and ultrastructural evaluations for submandibular glands. RESULTS: Sialograms showed a long, horizontal main excretory duct and a pear-shaped gland located inferoposterior to the angle of the mandible. The submandibular glands lied superficial to the suprahyoid, and infrahyoid muscle groups, and were covered by the inferior portion of the parotid gland. The submandibular glands were characterized by a mixed parenchyma of mucous and serous secretory acini. Alcian blue (AB) staining and periodic acid-Schiff (PAS) reactions demonstrated that minipig submandibular glands synthesized and secreted acid mucous substances by serous cells and polysaccharide, and neutral mucous substances, by mucous cells. CONCLUSION: The submandibular gland of the minipig is considered a useful large salivary gland animal model for biomedical studies.

[Tooth tissue engineering: from cells to organ, an odyssey far from finished].

Tooth tissue engineering is an emerging biotechnique that will provide replacemental teeth for patients suffering from different diseases causing tooth loss. Although some attempts have been tried to generate whole tooth both in vivo and in vitro, the lack of the knowledge for tooth initiation and development, as well as for tooth shape controlling mechanisms greatly impede the progress of this technique. This article reviewed and discussed some recent findings in tooth tissue engineering related to the cell resource, the concept of reconstruction and regeneration, the application of artificial scaffolds, together with the methods of organ culture and implantation.

[Psychiatric and central nervous system involvement in Sjogren's syndrome].

OBJECTIVE: To study psychiatric features and the manifestations of central nervous system involvement in Chinese patients with primary Sjogren's syndrome (PSS). METHODS: The Minnesota Multiphasic Personality Inventory (MMPI) was used to study 27 PSS female patients and 57 healthy women. The results from two groups were compared. Ten SS patients were evaluated by electroencephalography (EEG), transcranial doppler ultrasound (TCD) and magnetic resonance imaging (MRI). RESULTS: Of 27 patients tested, the three highest clinical mean scales included Hypochondriasis (Hs), Hysteria (Hy), Psychasthenia (Pt) were found. When PSS group was compared with normal control, T scores of SS patients were significantly higher than the healthy women in Hs, Hy. Abnormal EEG was found in 3 of 9 PSS patients. TCD was abnormal in 5 of 9 patients. MRI in 1 patient showed abnormality. CONCLUSIONS: This study shows that the personality of PSS patients is abnormal, the features are neuroticism. Central nervous system was markedly involved in Chinese patients with PSS, including abnormal EEG and TCD. The changes of central nervous system may be related to abnormalities of psychiatric changes.

[Effect of irradiation on tooth hard tissue and its resistance to acid].

OBJECTIVE: To study the effect of irradiation on the susceptibility of radiation caries. METHODS: The structures of 56 teeth enamel and dentin of 63 roots were observed using SEM and the collagen fibre and the resistance to the acid were also investigated after irradiation of 30 Gy, 50 Gy and 70 Gy. RESULTS: The enamel structure changes were found after irradiation with different doses. The significant difference was found in the enamel changes between high or middle dose group and low dose group or control. The dentin morphology changed, some collagen fibre vanished and resistance to acid was reduced after irradiation with 50 Gy and 70 Gy. CONCLUSIONS: The radiation reduced the resistance of teeth to the acid and increased the caries susceptibility.

[The study of the relationship of malodor and microbial composition of interdental and subgingival plaques in periodontitis patients].

OBJECTIVE: The study is to investigate the microbial composition of interdental and subgingival plaques of periodontitis patients with or without malodor, to explore the relationships between periodontitis and oral malodor. METHODS: 20 patients of periodontitis with malodor were chosen from 210 patients of periodontitis, and the clinical parameter of plaque index (PLI), gingival bleeding index (GBI) and probing depth (PD) were measured and compared with the control group which had periodontal disease without malodor. During the experiment, the interdental and subgingival microbial samples in both groups were collected and sent to anaerobic culture for 48 hrs, then the total CFU/ml of each sample were counted, and each type of bacteria was separated and identified. All of the data were analyzed by using the statistical software SPSS 10.0. RESULTS: (1) There were no satistical differences on PLI, GBI, PD between experimental group and control group. (2) The percents of leptospira in both interdental and subgingival plaques of test group were significantly higher than that of the control group (P < 0.01). (3) Either the interdental or in subgingival plaques, the count results of CFU/ml were similar in both groups (P > 0.05). (4) The proportions of malodor producing anaerobic bacteria in interdental gingival plaque, such as P. gingivalis and Veillonelia, were singnificantly different between test group and control group. CONCLUSION: The proportions of VSC's producing anaerobic bacteria in interdental gingival plaque may be play the significant roles in oral malodor. Further studies should be taken to elucidate the relationship between malodor and periodontitis.