Large area defect of intra-oral or extra-oral mucosa caused by mucosa lesions need suitable graft materials for repair.Tissue engineering methods can provide effective pathway to resolve this problem.Furthermore,full thickness mucosa equivalent constructed by tissue engineering methods also can be used as a model to evaluate dental materials,drug delivery system and oral carcinogenesis.Basic issues of tissue-engineered mucosa including sources of seed cells,scaffold materials such as de-epidermised acellular dermis,collagens,fibrin glue and biomacromolecule electrostatic spinning are discussed in this review,and the application researches of tissueengineered mucosa for mucosa reconstruction and mucosa model equivalents are expounded too.

As a new technique, photedynamic therapy was introduced in the end of 1970s and has been put into clinical application from experimental tests in recent years. Its mechanisms was established on the basis that a series of special typed cells and tissues could selectively absorb photosensitive drugs and generate photore-sponsive effects by light irradiation of definite wavelengths. Currently, the photodynamic theraputics is applied mainly in non surgical treatment of tumor betided in body superfacial and hollow viscus. Its application area has been expanded unceasingly in modern clinic due to the discovery of the selective aggregation of photoresponsive drugs to many pathological tissues and pathogenic microorganisms other than tumors, and the development of new photoresensitizer. In this paper, review is given on the effect mechanisms, the light sources and photosensitizer, as well as the application of photodynamic treatment of tumors in head and neck and its treatments of mucosal dis-ease and oral pathogenic microorganism infected diseases.

Optical coherence tomography (OCT) which was brought into existence in early 90s of 20 century is a noninvasive technique for creating cross-sectional images of transparent or semi-transparent internal biological tissue structure.In recent years applicability research in the field of stomatology has made great progress.The micro structure changes of surface layer of the lesions in oral hard and soft tissues could be detected by this technique,with its unique feature to detect insidious secondary caries beneath dental restorations that couldn't be found by current clinical techniques easily.In this review,secondary caries etiopathogenisis and diagnosis,principle were discussed firstly and then imaging observation of OCT to detect early second caries around dental restoration and monitoring on risk factors inducing secondary caries are reviewed.It indicated that OCT technique has great potential on diagnosis of secondary caries.

The experiment was conducted in the Central Laboratory of Tianjin Stomatological Hospital from November 2004 to March 2005. Epithelial cells were isolated from normal parotid gland tissues obtained form resected benign tumor of an adult, so as to prepare rat tail collagen. Two adult rats were selected to obtain the tendon fascia from rat tail, which were then immersed in the 500 mL of 0.1% glacial acetic acid. The infiltration culture board of collagen glacial acetic acid, proximal wall of culture flask and beaker with ammonia water were placed in a sterile containers to reserve at 37 ℃ for 72 hours. The epithelial cells were isolated from parotid gland tissues by enzyme digestion and cultured in 1:1 DMEM/F12 culture medium supplemented with some growth stimulating factors such as insulin (INS), hydrocortisone (HC) and isoproterenol (ISO) by using self-made rat tail collagen gel substrate. The cytomorphological characteristics of primary and passage cells were observed with inverted microscope. The result showed that the primary culture of parotid gland epithelial cells: cells were in polarity arrangement on the 4th day and formed in different size of acinus and pip kind structure. The serial subcultivation of parotid gland epithelial cells. In the culture period of 50 days, parotid gland epithelial cells were passed to the F3 generation, and the cells of F3 generation frozen in liquid nitrogen recovered and survived. It could be seen by HE staining that the cell body was bigger, the kytoplasm was abundant and the nuclear membrane was clear with one or two entoblasts. The karyogenetic division could be found in partial entoblast, whereas no abnormal karyogenetic division was seen.

BACKGROUND:Sodium alginate and chitosan are the polycation and polyanion natural polymer materials respectively, and they can be crosslinking agents complementing each other to form composite gel and avoid the cytotoxicity resulting from some common crosslinking agents .
OBJECTIVE:To prepare the chitosan-sodium alginate composite gel and evaluate its cytotoxicity in vitro. METHODS:Chitosan was dissolved in 0.25 mol/L acetic acid to make a 30 g/L mass concentration solution, and 0.1 mol/L NaOH solution was added to neutralize its acidity. Neutralization of the chitosan solutions leads to the formation of a precipitate in ultrasmal particles. Then the chitosan and 3%sodium alginate solution in deionized water were mixed in 1:1 volume ratio by high frequency oscil ating to produce composite gel. The composite gel were detected by scanning electron microscopy and Fourier transform infrared spectrometry after freeze-drying. The 24-hour and 72-hour leaching solutions of composite gel, 24-hour and 72-hour leaching solutions of polyethylene and phenol solution were added to the L-929 cells’ culture medium respectively in order to evaluate the cytotoxicity of composite gel in vitro.
RESULTS AND CONCLUSION:The results of Fourier transform infrared spectrometry showed the variation of characteristic peak values of composite gel which were different from sodium alginate and chitosan;and under scanning electron microscope, a spatial network structure formed with abundant intervals. Result of the cytotoxicity valuation was qualified for the chitosan-sodium alginate composite gel. These findings indicate that the chitosan-sodium alginate composite gel can be used as tissue engineering scaffold materials.

OBJECTIVETo explore the efficacy of optical coherence tomography (OCT) in imaging and quantitatively evaluating early enamel caries and provide experimental evidence for the clinical diagnosis of early caries.

METHODSThe smooth surface of bovine teeth showing early artificial caries and demineralization changes was scanned by an all fiber-based OCT for images and optical profiles, which were compared with images from a polarized light microscope (PLM) and mineral loss from an atomic absorption spectrometer. Data were analyzed by paired-sample t-test and Pearson correlation analysis using SPSS software.

RESULTSThe images of enamel with early caries and demineralization from OCT coincided with those from PLM. The integrated reflectivity loss in the early caries group was significantly lower than that in the demineralized group (P < 0.05), whereas no significant difference in demineralized depth was found between the two groups (P > 0.05). A linear correlation was observed between integrated reflectivity loss and mineral loss (P < 0.05).

CONCLUSIONOCT can be used to nondestructively and accurately image early caries and quantify lesion extent and degree, suggesting the extensive use of this approach in the clinical diagnosis of early caries.

Objective Quantitative analysis of optical coherence tomography (OCT) images of naturally occurred early enamel caries was performed to find quantitative parameter indicator for detecting early caries by OCT.Methods Three human premolars with enamel natural caries in D0,D1,and D2 stages were selected respectively and scanned by OCT.The ratios of the average gray value of the caries region (object region) and sound region (background region),namely,the object-background contrast (OBC) were calculated in OCT images and selected as the quantitative parameters to analyze the OBC trend of different degree of enamel caries.Results Within the fixed depth,the OBC value showed a trend of first increase and then decrease with the severity of dental caries,indicating that OBC value increased with the severity of dental caries from normal to D1 stage,and then decreased from D1 to D2 stage.Conclusion The OBC value can be used as a new quantitative indicator for OCT to estimate the severity of naturally occurred early caries.

2 mmx3 mm experimental windows were prepared in adamant slippery surfaces of 7 fresh uprooted permanent teeth. The teeth surfaces in the windows area were demineralized to create artificial caries mould of early stage by aciding the experimental teeth surfaces of 0, 12, 24, 48, 72, 96, 120 hours with demineralized liquid (pH 4.5) in vitro. The demineralized changes on the experimental teeth surfaces were detected by dental Optical Coherence Tomography (OCT) system, which were newly developed by our research group recently, and the detecting results were compared with clinical digital photomicrography and scanning electron microscopy on the same tooth sample, to checkout the efficacy and feasibility of dental OCT for early quantification detecting of artificial enamel demineralization in vitro. The dental OCT system can safelydetect early enamel demineralization of micron level and noninvasively obtain fine resolution quantification information both in surfaces view and sectional view; OCT could accurately detect surface demineralization changes on the experimental windows of artificial dental caries as early as after 12 hours aciding treatment, earlier than the visual inspection and clinical digital photomicrography. OCT could obtain both superficial view and sectional view of quantificational demineralization in early enamel caries homeochronously, and had high correlation to the results of ultramicromorphological changes detected by scanning electron microscopy. Dental OCT system developed by our group could accurately detect early artificial dental caries atraumaticly with high sensitivity and safety. Moreover, it can obtain quantification data in micron level without damaging the experimental teeth samples.

Pulp necrosis can cause increased tooth fragility and easy fracture, and hinder the sustainable development of young permanent teeth. Therefore, pulp regeneration therapy has important clinical significance. However, due to the complicated and varied anatomical structure of the pulp tissue, and various components such as nerves and blood vessels, there are many challenges in dental pulp regeneration strategy. In this paper, the recent research progress in the application of dental pulp tissue construction and transplantation by tissue engineering method was reviewed, and the selection of suitable scaffold materials and the construction of dental pulp tissue were discussed. The functional characteristics of scaffold materials were described,such as sodium alginate, chitosan, hyaluronic acid, collagen, gelatin, fibrous protein, silk fibroin, peptides and self-assembled peptides, polylactic acid, polyglycolic acid and their copolymers. In addition, the functions and characteristics of these materials were briefly introduced, as well as the functional modification with growth factors and other biological matrix extract involvement, and functional improvement of the composite scaffolds with complementary effects.Combined with the requirements of clinical operability, the composition design and functional characteristics of the injectable hydrogel scaffolds consisted of hydrophilic composite materials and/or modified with hydrophilic groups were also discussed.This review paper would be useful in providing some reference for the future research and exploration of dental pulp regeneration.