Objective: To study the relationship between occurrence and development of chronic periodontitis and neuropeptide substance P (SP) in gingival crevicular fluid. Methods: There were 48 patients in experimental group and 42 patients in the control group. Gingival crevicular fluid samples were collected from the patients′ intraoral chronic periodontitis inflammatory positive sites and healthy sites. Neuropeptide substance P levels in gingival crevicular fluid from two groups were measured by radioimmunoassay. Gingival index, pocket depth, attachment loss, alveolar bone resorption were recorded and their correlations with SP were analyzed. Results: SP levels of the experimental group were significantly higher than those of the control group(P<0.01). There were significant differences(P<0.01)between SP level and periodontal clinical index in slight periodontitis and the control group. There were significant correlations(P<0.05)between GCF SP content and all PD, AL, ABL but GI in slight periodontitis, and there were significant correlations in between GCF SP content and GI for both moderate periodontitis and severe periodontitis. There were significant correlations(P<0.01) between GCF SP content and PD,AL,ABL for both moderate periodontitis and severe periodontitis. Conclusion:GCF SP level is closely related to occurrence and development of chronic periodontitis.GCF SP level can reflect the degree of the damage of periodontium.Determination of patients′ GCF SP level has important significance for the patients′ condition judgement and treatment guidance.

Objective: To investigate the relationship between TIMP-1 gene polymorphisms and susceptibility of chronic periodontitis(CP) in Han Cantonese. Methods: Buccal swabs from 70 CP patients and 74 periodontal healthy controls were collected. DNA was extracted from these buccal swabs by using Chelex-100. TIMP-1 +372T/C (rs4898)、TIMP-1+533C/T (rs1062849) polymorphisms were tested by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP). Allele distribution and genotypes frequencies in the patients and controls were analyzed. Results: Frequency variance of allele T and C at site of TIMP-1 +372 in patients and controls showed no statistical difference. TIMP-1+533C/T polymorphism of TIMP-1 hadn't been found in the present study. Conclusion: There is no relationship between TIMP-1 +372T/C polymorphism and susceptibility of chronic periodontitis, and TIMP-1 +533C/T polymorphism doesn' t exist among Han Cantonese.

Objective: To evaluate the corrosion resistance of Ni-Cr alloy with different coatings in neutral and acid saliva by electrochemistry method. Methods: Measured the self-corrosion potential (Ecorr) and polarization resistance(Rp) curves of Ni-Cr alloy models with different coatings in neutral and acid artificial salivas. Results: The Ecorr of the Ni-Cr alloys all showed positive values, the electrochemistry corrosion and galvanic corrosion were not detected. Conclusion: Ni-Cr alloy with titanium nitride coating, gold electroplating coating, gold-paste layer and gold-porcelain blended layer have both anti-corrosion and esthetical function without changing its own property.

Objective: To evaluate bond strength and interface of various dentin adhesives by a modified interface processing method. Methods:Nine extracted human molars were ground to expose fresh dentin surface. Three dentin adhesives (Single Bond, Clearfil SE Bond and Clearfil S3 Bond) were applied respectively and a block of composite resin was built up. The specimens were then stored in distilled water for 24 h at 37 ℃ and sectioned into beams of 0.9 mm×0.9 mm cross-sectional area. The microtensile bond strength was determined with Microtensile Tester(n=15). In addition, the bonding specimens were conditioned with 6 mol/L HCl, 5% NaOCl and 0.08 mg/ml hyaluronidase to observe the adhesive interfaces by SEM. Results: Significant differences in bond strength were observed among the three adhesives(P<0.05): SE Bond (45.06±5.29) MPa> Single Bond (35.50±6.40) MPa> S3 Bond (30.46±3.82) MPa. Single Bond showed resin tags about 9-12 μm long and gaps between hybrid and adhesive layers. No obvious boundary between hybrid layer and adhesive were observed for both SE Bond and S3 Bond, while the length of resin tags were 9-14 μm and 4-7 μm for SE Bond and S3 Bond respectively. Conclusion:The morphology of the bond interface of dentin adhesive has a relationship with the bond strength.

Objective:To investigate the corrosion fatigue strength of laser-welded specimens fabricated from commercially pure titanium (TA2) and titanium alloy(TC4). Methods:TA2 and TC4 were mechanically processed into a certain size and joined by laser welding. A fatigue testing machine was used to test tensile load and fatigue strength after soaked in synthetic saliva. The fatigue fracture surface was examined by scanning electron microscopy (SEM). Results: The fatigue strengths of the laser-welded test specimens showed no significant differences compared to specimens in air. SEM examination showed that there were no defects such as corrosion pits. Conclusion: There are no significant differences between either laser-welded metal in the corrosion fatigue strength for dry specimens and specimens in synthetic saliva.

Self-ligating brackets have been developed for decades. Now more and more orthodontists are using self-ligating appliance systems, because they have the following advantages over conventional orthodontic brackets: less friction between the archwires and the brackets;simple clinical operation;comfortable for patients. This review introduces the self-ligating brackets' feature, classification and several self-ligating brackets applied in clinic.

The whole process of mini-implant was introduced, including preparation, operating methods, points for attention during the procedure, post-operation of implanting and the medical orders. Principles of implanting position and eight normal positions of implanting were introduced. These might be useful for clinical application.

The mandibular canine usually has a single-root with a single canal. A case of a patient who has a mandibular canine with two well-defined roots and two root canals was reported. Size of the lingual root and buccal root was equal. The buccal root length was 24.5 mm. The lingual root length was 23.0 mm. Clinicians should be aware of the anatomical variation that exists in mandibular canines in practice.

Full ceramic prosthesis is becoming the main prosthetic development direction. As an important kind of full ceramic prosthesis, full ceramic veneer has not only natural cosmetic appearance and perfect biocompatibility, but also can preserve tooth structure as much as possible, which would be more easily accepted by patients for cosmetic prosthesis. Many methods, such as slip casting, die casting and CAD/CAM technology are available to make full ceramic veneer. All the methods have their own advantages and disadvantages. Slip casting is easy to be developed widely with low cost, so be used in practical work. In this article, the working process of full ceramic veneer, especially manufacture of removable dies, duplication of refractory models, were introduced, which was supposed to be beneficial for the technicians.

To observe the clinical effects of Depulpin in deciduous teeth. It was suggested that Depulpin was an effective and safe drug for pulp devitalizer in children.