To summarize the application of laser in the treatment of periodontal disease.Researches have proved that laser can clean more than 97%periodontal pathogens，and laser also can remove infected cementum effectively with little damage on periodontal tissue and tooth root.Laser also can alleviate pain in treatment.So laser may have potential application in periodontal therapy in future.

Objective To test the effect of alcohol on force decay of elastomeric chains in vitro . Methods Elastomeric chains of close type were divided into five test groups.Three test groups were exposed to different alcohol concentrations (14.0%and 26.9%),mouth rinses (26.9%alcohol and 0%alcohol) and artificial saliva for 60 seconds twice a day.The chains were stretched to produce the initial force of 2.45 N.Then the experiment groups were arranged by the orthogonal design,and the stretched length of different groups of chains were maintained respectively in artificial saliva environment of 37 ℃.The remaining forces of the elastomeric chains were recorded at different moments in 4 weeks.Then the percentage of remaining force was calculated. Results Test groups with the treatment of alcohol/alcoholic mouthwash water had a lower remaining force of the elastomeric chain at each measurement time point and a higher percentage of force degradation than the control groups,and the difference was statistically significant.The force of elastomeric chain gradually decreased over time,under the condition of thermal cycle.The force degradation was the fastest within 24 hours.Force decay percentage increased slightly between 24 hours and 28 days. Conclusions Alcohol can exacerbate the force degradation of elastomeric chain.The force of elastomeric chain stabilized after 24 hours under the condition of thermal cycle.

Abstract： Objective To learn the effects of oxidative stress on the rat with dental fluorosis caused by coal burning. Methods　High fluoride(F—) air modle was established by burning the fuel,clay rich of F—mixed with coal for 10h a day. Rats were fed with drying corn with different proportions. Thirty SD rats were randomly divided into 5 groups: the high F— air and fed F— 40mg/kg group(H),the high F— air and fed F— 25mg/kg group(M),the high F— air and fed F— 10mg/kg group(L), the high F— air and common food group(A) and the control group(C). All rats were killed at the end of 16th week, and then the activities of SOD, CAT, GSH and MDA levels were measured with their reagent boxes respectively. Results　The dental fluorosis in rats was replicated successfully. The MDA level of the experimental group increased (P<0.01 or P<0.05), while SOD and CAT activities decreased (P<0.01 or P<0.05).No statistically considerable differences was found in GSH level (P>0.05).SOD activities of liver and kidney decreased only in group A(P<0.05). Conclusions　The balance of oxidative and anti-oxidative system may be broken in the rat because of the high F— air. In the occurrence process of coal-burning source dental fluorosis, the oxidative stress of liver and kidney tissue may be earlier than the dental hard-tissue damage caused by high F— air.Oxidative stress may be an important mechanism for body damage and the occurrence of dental fluorosis.

Objective To investigate the effect of various working time on the adhesive property of two commercial dual-cured resin cements. Methods 60 extracted human premolars were randomly assigned to two groups. Two commercial resin cements（EmbraceTM and ParaCore） were used to cement at three kinds of working time（1 min，3 min and 7 min).The whole process was conducted at 25 ℃. After 24 h, each tooth was embedded by PMMA. Then each tooth was sectioned into three blocks that were approximately 1mm thick from the coronal, cervical and apical parts of the tooth. All bond strength of specimens was tested by a universal testing machine. Contrast adhesive interface between original and tested specimens was observed by scanning electron microscope（SEM）. Results There was statistically significant difference in bond strength between ParaCore and EmbraceTM. The bond strength of ParaCore was higher than EmbraceTM at all kinds of working time. But as working time was 1 min, the cervical specimens of ParaCore showed higher failure rate than the same parts of EmbraceTM. Bond strength and failure rate decreased with the increase of the working time .Conclusion Although ParaCore can produce a higher adhesive property, clinical controlled time (CCT) is shorter, and it is more easily affected by the operational environment and it fails more easily. Although EmbraceTM bonding performance is weaker, its CCT is longer, and it is less susceptible to external environment influence. Whatever the bonding system is, the light curing time should be extended, to ensure sufficient time to work on and at the same time get better bonding strength and mechanical properties of the materials.

Objective To determine the effect of epigallocatechin-3-gallate (EGCG) on the proliferation and adipogenic differentiation of bone marrow-derived mesenchymal stromal cells (BMMSCs) and to investigate the underlying molecular mechanism and involved signaling pathway. Methods 　To assess the effects of EGCG on the proliferation and adipogenic differentiation of BMMSCs,MTT and Oil red O staining were conducted respectively.The expression levels of key transcriptional factor during adipogenesis,including PPARγ,C/EBPα and C/EBPβ were measured by Real-time fluorescent quantitative RT-PCR.Also,Western blot was performed to confirm the role of ERK1/2 pathway in the inhibitory effects of EGCG on the adipogenic differentiation of BMMSCs. Results 　Although low concentrations of EGCG (1-10 mmol/L) exhibited no effects on BMMSCs growth,high levels of EGCG (20-40 mmol/L) significantly decreased the cell proliferative reaction.By inhibiting the expressions of PPARγ,C/EBPα and C/EBPβ,three key transcriptional factors in adipogenesis,EGCG also showed abilities to suppress the adipgenic differentiation of BMMSCs.ERK1/2 pathway was demonstrated to play an essential role in EGCG inhibiting adipogenesis. Conclusions 　EGCG can suppress the adipogenic differentiation of BMMSCs via ERK1/2 pathway.

Objective To analyze the structure around the mini-implants between maxillary second premolar and first molar or mandibularsecond molar with Cone-beam computed tomography (CBCT) for the clinical plantation of mini-implants. Methods A total of 34 subjects were selected from patients who had undergone CBCT examinations.The distance between the simulative mini-implants and the occlusal plane and the thickness of maxillary infrazygomatic crest at different insertion angles were measured.The smallest angle and the thickness ofbuccal alveolar bone of the simulative mini-implants in different insertion heights were measured in the mandible. Results ① When the insertion angle was 40° to 75°,the thickness of the infrazygomatic crest was (4.7±0.3)～(8.0±0.1)mm,13～17 mm from the maxillary occlusal plane.②In different insertion cases,the insertion angle should be greater than 82°,11 mm from the mandibular occlusal plane.The buccal alveolar bone of the mandibular second molar was the thinnest.While the distance was 16 mm,the insertion angle should be greater than 51° and the buccal alveolar bone was the thickest.③ The distance to the mandibular tube was the shortest((9 ± 1.6)mm) when the insertion site was 16 mm from the occlusal plane among different insertion sites. Conclusions ①To ensure that the thickness of the infrazygomatic crest was greater than 6 mm and not touching the inferior wall of the maxillary sinus,the ideal insertion site was 13～16 mm from the maxillary occlusal planeat the angle of 55° to 75°.② When the insertion site was buccal to the mandibular second molar,the distance of mini-inplant to the occlusal plane should be greater than 12 mm.The smallest insertion angle variedfrom the insertion sites.

Objective To evaluate the effect of low-power laser therapy in treatment of painful arthrosynovitis of temporomandibular joint. Methods 60 patients with arthrosynovitis of temporomandibular joint were randomized into three groups:low-power laser therapy,ultrashort wave and fomentation therapy.Scores of pain visual analog scale,the maximum of mandible open and protrusive position were recorded and analyzed. Results Pain of all patients was relieved after treatment in three groups.The effects of low-power laser,ultrashort wave therapies were better than that of fomentation therapy. Conclusion Low-power laser therapy is a reliable clinical treatment for painful arthrosynovitis of temporomandibular joint.

Objective To evaluate the effect of neodymium-doped yttrium aluminium garnet (Nd:YAG) laser assisting initial therapy of periodontal diseases by Meta-analysis. Methods The periodical literature,conference paper and academic dissertation of Chinese were scanned by electronic retrieval and manual search,and then the clinical studies which compared Nd:YAG laser assisting initial therapy of periodontal diseases to initial therapy of periodontal diseases alone were collected.According to inclusion and exclusion criteria,the quality assessment of these included studies,the data extraction were done and the heterogeneity test,the Mate-analysis were conducted.We also test the publication bias of the outcome by Meta-analysis. Results We adopted ultimately 8 studies into our research,of which the observation index was effective rate of 5 studies, while for remaining 3 studies the observation targets were PD(pocket depth),AL(attachment loss) and BI(bleeding index).There were no statistically significant differences in all the results of meta-analysis,except PD before and 3 months after SRP by Nd:YAG laser assisting initial therapy of periodontal diseases,accordingly no significant publication bias was found. Conclusions There was significant improvement in clinical efficiency on PD before and 3 months after SRP(scaling and root planning,SRP) by Nd:YAG laser assisting initial therapy of periodontal diseases,while the rest outcomes should be researched further patiently.

Objective　To analyze the possible function improvement after removal of inducing factors for unilateral mastication. Methods 　As the experimental group, 30 patients with unilateral mastication (male or female) were randomly selected by adopting the methods of combining clinical stomatology examination with inquiry, including 13 cases with left side chewing and 17 cases with right side chewing. The common inducing factors for unilateral mastication had been removed before the experiment. The absorbance value was tested and analyzed to compare masticatory efficiency under the circumstances of random chewing, left side and right side chewing respectively. Bilateral chewing people were randomly selected as the normal control (n=30, male or female). Results　There was significant difference in absorbance value between the experimental group and control group (P<0.01), while no significant difference was found between male and female cases in each group (P>0.05). In the experimental group, although there was no significant difference in absorbance value between random chewing and left side chewing for left side chewing people (P>0.05), each of them was higher than that of the right side chewing (P<0.05). Moreover, no significant difference was found between random chewing and right side chewing (P>0.05), but each of them was higher than left side chewing (P<0.05) for right side chewing people. Conclusions　After the removal of inducing factors for unilateral mastication, the masticatory efficiency of unilateral mastication cases is still lower than bilateral chewing group, suggesting that the conventional removal of inducing factors for unilateral mastication can not really achieve the purpose of restoring bilateral masticatory function, and a therapeutic intervention may be necessary as well.

Objective To evaluate the masticatory efficiency of long-centric occlusal complete denture in re-treatment of edentulous patients. Methods 20 edentulous patients were selected (2011.1-2013.8).A long-centric occlusal denture was made for each patient and the denture was used as the template to remake an anatomy occlusal denture using denture replication technology.Each patient alternatively wore the long-centric occlusal denture and anatomical occlusal denture for three months or more.The masticatory efficiency measurement was taken with UV-2450 spectrophotometer. Results The two kinds of occlusal type 30 seconds masticatory efficiency absorbance values:long-centric occlusal complete denture (0.898) was significantly higher than that of anatomy occlusal complete denture (0.657), t =8.581, P< 0.001,and there was significant difference in chewing efficiency between the two kinds of occlusal type. Conclusions The masticatory efficiency of 20 cases of long-centric occlusal complete denture re-treatment of edentulous patients is higher than that of the anatomy occlusal denture.

Objective 　To explore safe,simple and effective treatment method for masticatory muscle spasm through the treatment of 90 patients. Methods 90 patients were divided into three groups (A,B,C) randomly.Patients in group A received Chinese medicine local fomentation; patients in group B were treated by Chinese medicine local fomentation combined with TDP treatment,and patients in group C only received simple fomentation.The therapeutic effects were evaluated after 2 treatment sessions. Results The effective rate(96.7%) in group B was significantly higher than that in group A(76.7%) and group C (60.0%). Conclusions Chinese medicine local fomentation combined with TDP treatment has a good therapeuticeffect on masticatory muscle spasm.

Objective To explore the new method of non-extraction treatment of anterior crossbite with severe crowding cases. Methods With the application of multi-purpose face bow in 12 cases with anterior crossbite and severe crowding,maxillary protraction and molar distalization were going on at the same time,so some clearance was provided in a short period of time for crowded teeth. Results Molar distalization was achieved and the anterior crossbite of 12 patients was corrected within a short period of time and some gaps between teeth were provided for crowded teeth,so the extraction treatment had been avoided. Conclusions The multi-purpose face bow is composed of face bow and maxillary protraction.The reverse reaction of maxillary protraction can lead to molar distalization.It can be used together with headgear.It can significantly improve the efficacy and shorten the course of treatment.The clinical application of this appliance can be effective in reducing cases of extraction treatment.

Objective To investigate the effect of magnetic-orthodontic extrusion on impacted teeth and its potential value. Methods 36 patients who received dental treatment in our hospitals from April 2008 to April 2012 were chosen as the study subjects with 29 impacted maxillary canines and 7 impacted maxillary central incisors.36 patients were then randomly divided into two groups:Group A (surgical joint fixedappliance) which underwent a surgical fenestration joint fixed appliance therapy and Group B (surgerycombinedmagnetictraction) which underwent a surgical fenestration combining magnetic traction therapy.Gingival-breaking time,into the column time,the eruption of the situation,pulp and degree of patient pain of two groups were observed. Results Compared with Group B,the average gingival-breaking time and into the column time of Group A were less,but the difference was not statistically significant ( P >0.05).Pulp vitality tests were normal in group A without root resorption and adhesion,but the traction parts of the gums and lips had obvious traction oppression signs,and patients felt haulage pain when doing such lip movements as speaking and eating.Pulp vitality tests were normal in group B without root resorption and adhesion,and there were no infections in the traction parts and no abnormalities in the gums and lips and the patients felt no pain. Conclusions Although the treatment time is slightly longer,surgical fenestration combining magnetic traction therapy has broad application prospects in treatment of the impacted teeth due to its gentle traction and less pain.

Objective To observe the changes of the contents of matrix metalloproteinase (MMP-2) and tissue inhibitor of metalloproteinase (TIMP-2) in the gingival crevicular fluid (GCF)varying with the differences of orthodontic traction on human teeth,and to explore the relationships between MMP-2 and TIMP-2 functions and the orthodontic traction in the process of tooth movement. Methods Twenty four patients were selected as subjects and divided into three groups randomly:control group (0 N),mild force group (0.5 N),and moderate force group (1.5 N).The traction of canine tooth to distal ends was exerted for 0 days,7 days,14 days and 28 days,and then GCF was collected and the changes of MMP-2 and TIMP-2 contents in GCF were measured by western blot. Results In the experimental groups,MMP-2 and TIMP-2 contents have demonstrated volatility changing feature and were time-dependent; there were significant differences between groups ( P< 0.05). Conclusions Firstly,the expressions of MMP-2 and TIMP-2 demonstrate volatility changing feature,and are time-dependent under mild and moderate forces.Secondly,MMP-2 and TIMP-2 participate in the process of periodontal tissue remodeling and their dynamic balance plays an important role in tooth movement.

Periodontitis and chronic kidney disease (CKD) are both chronic inflammatory disease.In many patients,these two kinds of disease are accompanied by immune inflammatory burden and systemic anomalies.Blood glucose,blood pressure and blood lipid abnormalities，even the inflammation stimulus may have a significant effect on them.This paper mainly focused on the epidemiological studies of periodontitis and CKD,their common factors,the possible biological related mechanism and so on.The aim of the study is to make early disease prevention,control risk factors and reduce the risk of interaction between two diseases.It also may guide clinical treatment in order to achieve good prognosis.

Neuropilin-1(NRP-1) is a transmembrane glycoprotein that acts as a co-receptor.And it is adjusted by miR - 9,miR - 124,miR - 181 - b,miR - 320,and it participates in the above cytokine signaling pathways,which is closely related with tumor angiogenesis and metastasis.Preliminary studies that show NRP-1 expression on T cells confers enhanced immunosuppressive activity.Some suggest a specific role for NRP-1 in cancer pathology.This article reviews current Knowledge on the structure and function of NRP-1,as well as its research status.

Periodontitis is a chronic inflammatory disease,and oral lichen planus（OLP）is common in oral mucosal disease.In clinic,most OLP patients have poor periodontal status,and periodontal non-surgical treatment has an effect on it.In the pathogenesis,oral lichen planus and periodontitis are both related to immunity,genetics,psychological factors,and etc.Periodontitis and oral lichen planus can both exist,even for the whole life.Actually,health maintenance on periodontal tissue is the biggest problem that every dentist must face.This review has discussed the relationship between periodontitis and oral lichen planus to lay a foundation for the further study.

In recent years,to improve the bonding performance of dentin and the resin cements,the domestic and international scholars have carried out extensive researches in regard to the dentin surface treatment.The rapid development of laser technology provides a new way to dentin surface preparation.The paper has made a review from the flowing five aspects:the classification and characteristics of resin cement,laser pretreatment principle,types and characteristics of commonly used laser,the influence of laser pretreatment on dentin surface morphology and the effect on the properties of resin cement.