BACKGROUND: The shear bond strength between ceramic orthodontic brackets and teeth is so large that ceramic brackets are not easily eliminated safely. Whether the shear bond strength of self-etching primer/adhesive can be decreased and the injuries to enamel can be reduced has been always concerned by orthodontists. OBJECTIVE: To evaluate the bond strength between self-etching primer/adhesive system and ceramic orthodontic brackets and make a comparison with Jingjin enamel adhesive most commonly used by clinicians in China.DESIGN, TIME AND SETTING: Controlled observation, performed at Hebei University of Science and Technology in March 2006.MATERIALS: Twenty permanent premolars extracted due to orthodontic treatment were selected. The premolars were required to have excellent enamel and gloss, no cracks or carious lesions, and have not been given any chemotherapy. Ceramic orthodontic brackets were arch wire ceramic premolar brackets with 0.022-inch standard edgewide (3M company,USA). The bottom bracket area was 12.16 mm2. Self-etching sealant and TransbondTM fight-cure adhesive were purchased from 3M company, USA. Jingjin enamel adhesive, a conventional self-etching adhesive, was provided by Tianjin Institute of Synthetic Materials Industry, China.METHODS: The 20 premolars were randomly evenly divided into a self-etching primer/adhesive group, in which,self-etching sealant and TransbondTM fight-cure adhesive were applied, and a Jingiin enamel adhesive group, in which,Jingjin enamel adhesive was used.MAIN OUTCOME MEASURES: After 24 hours, shear bond strength was determined respectively in the two groups using anti-shearing testing machine. Simultaneously, residual adhesive remaining on the teeth was examined. RESULTS: The mean shear bond strength was lower in the self-etching primer/adhesive group than in the Jingjin enamel adhesive group, but there was no significant difference (P > 0.05). The mean shear bond strength in the two groups was clinically acceptable. The residual adhesive remaining on the teeth was significantly less in the self-etching prime/adhesive group than in the Jingjin enamel adhesive group (P < 0.01).CONCLUSION: Self-etching prime/adhesive system used for bonding ceramic orthodontic brackets can satisfy clinical requirements. Moreover, its bond strength can be appropriately decreased and ceramic brackets are easily removed, thereby,injuries to enamel can be reduced.

BACKGROUND:During clinical orthodontic correction, the self-ligating bracket is more helpful to maintain the periodontal healthy than the traditional bracket, but previous studies mainly focused on the clinical periodontal index and periodontal pathogens, and whether inflammatory cytokines are involved has not been reported. OBJECTIVE:To analyze the changes of the expression levels of interleukin 1β and tumor necrosis factor α in gingival crevicular fluid before and after the correction using self-ligating bracket and conventional bracket appliance. METHODS:Totaly 38 orthodontic patients without periodontal disease (including 20 males and 18 females; aged 11-25 years) were included in this study. Al the patients were randomly divided into control and test groups (n=19/group) and subjected to orthodontic correction using self-ligating bracket and conventional bracket appliance, respectively. The volumes of gingival crevicular fluid and expression levels of interleukin-1β and tumor necrosis factor-α were detected before correction and at 4, 8 and 12 weeks after correction. RESULTS AND CONCLUSION: The volume of gingival crevicular fluid and expression levels of interleukin-1β and tumor necrosis factor-α after correction were al higher than those before correction (P< 0.05). The volume of gingival crevicular fluid and expression levels of interleukin-1β and tumor necrosis factor-α after correction in the test group were lower than those in the control group (P< 0.05). These results demonstrate that self-ligating bracket appliance is more conducive to protect the periodontal tissue than the conventional bracket appliance.

BACKGROUND: Resin-modified glass ionomer (RMGI) cements have higher bond strength, especially can release fluoride. But there are fewer reports of the clinical application for the prevention of decalcification.OBJECTIVE: To test the benefit from using RMGI cement instead of a conventional composite resin in bracket bonding for patients with malocclusion, and observe bracket-failure rates and decalcification on enamel surfaces at pretreatment and at debonding.DESIGN: Observational and comparative trial.SETTING: The Second Hospital Affiliated to Hebei Medical University.PARTICIPANTS: Forty successive patients (358 teeth) with malocclusion admitted to the Department of Orthodontics in the Second Hospital Affiliated to Hebei Medical University, were selected for the study from July to August in 2002. All the patients (21 females and 19 males, mean age 16 years) had normal and complete anterior teeth, good oral hygiene. There were no obvious differences in bilateral teeth. Informed consents were obtained from all the subjects. The experiment was also approved by the ethical committee of the hospital. Experimental materials were RMGI adhesive (Fuji, GC, Japan, Lot 0005111) and composite resin cement (enamel adhesive of Beijing and Tianjin, Tianjin product, Lot 020402). Brackets produced from Hangzhou 3B and 37% phosphoric acid were used.METHODS: ①Bonding brackets: Subjects selected according to random procedure were divided into two groups, each with 20. GroupⅠ: The left buccal surfaces bonded with light-cure RMGI were etching for 30 seconds with 37% phosphoric acid, rinsed with water; the right buccal surfaces bonded with composite resin cement were etching for 60 seconds with 37% phosphoric acid, rinsed with water and dried; Group Ⅱ: After etching for 30 seconds with 37% phosphoric acid, the right buccal surfaces were rinsed with water and bonded brackets with light-cure RMGI. The left buccal surfaces were bonded brackets with composite resin cement after etching for 60 seconds with 37% phosphoric acid, rinsing with water and drying; Attachment of 0.036-cm NiTi wires with ligature to the brackets was conducted 10 minutes after light-curing. The information about differences in bilateral bonding materials was not told to patients. To ensure an equal bonding materials containing fluoride and minimize the error, all the patients were instructed to use toothpaste containing fluoride, a fluoride mouthwash was not prescribed. The treatment period was 9-26 months (mean 18 months).②Patients were rechecked at intervals of 4 weeks postoperatively. Each bonded tooth was checked for loose or missing brackets, and failures were recorded. A color transparency of anterior teeth area was taken using a standardized photographic technique. The enamel surface conditions were classified at a magnification of ×10. The condition of enamel surface recorded was made according to the scoring system by Geiger before treatment and at debonding.MAIN OUTCOME MEASURES: ①The number and site of bonding failures.②Enamel surface conditions at before treatment and debonding.RESULTS: Forty patients were all involved in the result analysis. Eliminating 4 teeth occurring bond failure and 4 teeth of opposite side at anterior teeth, a total of 232 teeth were evaluated.①The number and sit of bonding failures: There was no significant difference between the failure rates of RMGI adhesive and composite resin cement (P > 0.05). Significantly more premolar brackets failed than incisor brackets.②Decalcification of enamel surface: At debonding after treatment, the incidence rates of white spots in the surfaces bonded with the RMGI were significantly lower than that in the composite resin (25.9%, 38.8%, P < 0.05).CONCLUSION:The use of RMGI for brackets bonding results in a significant reduction in the incidence of white spot at debonding. Reducing etching time may obtain a similar survival rate with the routine etching time.

BACKGROUND:The patients are suffering from peritoneal adhesions that are caused after abdominal operation. As so far, there is stil no effective drug or method that can completely prevent peritoneal adhesions. Carboxymethyl chitosan is a biocompatible and biodegradable biomedical material with anti-adhesion effects, which is an ideal biomaterial for prevention of peritoneal adhesion theoreticaly.
OBJECTIVE:To investigate the novel anti-adhesion properties of carboxymethyl chitosan anti-adhesion solution on the prevention of postsurgical adhesion in vivo in a rat model.
METHODS:Fifty-six adult male Wistar rats were randomly divided into four groups: 0.9% normal saline solution (group A), hyaluronic acid gels (group B), medical chitosan gels (group C) and carboxymethyl chitosan anti-adhesion solution (group D). The model of postoperative intestinal adhesion was established by making cecal scratches/abdominal wal defects. Al the rats were scarified after 2 or 3 weeks. Whole blood was colected by cardio-puncture, lung tissue and tissue adhesion were stripped. The incidence and degree of adhesions, histological effects, expression of transforming growth factor-β1 (TGF-β1), the amounts of hydroxyproline and white blood cels were observed.
RESULTS AND CONCLUSION:The formation of postsurgical adhesions in groups B, C and D was significantly decreased, which was lighter than that of group A (P < 0.05). Furthermore, the adhesion formation in group D was significantly decreased in comparison with group A (P < 0.01). At the same time, the levels of transforming growth factor-β1, hydroxyproline and white blood cels in group D were lighter than those of group A (P < 0.05), and the histopathological results indicated that a marked reduction in inflammatory cels and fibroblasts. Carboxymethyl chitosan anti-adhesion solution can effectively reduce the degree and incidence of postoperative adhesion, and it is becoming a promising drug delivery system in the context of postsurgical anti-adhesion.

OBJECTIVES: The expression of osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) in human periodontal ligament cells (HPDLCs) was investigated by cell culture under continuous static pressure. METHODS: HPDLCs were primarily cultured by tissue explant method and divided into three groups: group A (13-18 years old), group B (19-29 years old), and group C (30-44 years old). CCK-8 was used to detect the proliferation of HPDLCs. The senescence of HPDLCs was detected by senescence-associated β-galactosidase staining. Cells in the three groups were respectively given 0, 1.5, 3, 6, 12, 24, 48, and 72 h of continuous static pressure in vitro. The expression of OPG and RANKL in the supernatant was detected by enzyme-linked immunosorbent assay. RESULTS: After continuous static pressure in vitro for stimulation, the expression of OPG and RANKL changed. The expression of OPG increased with time and age (P<0.01). The expression of RANKL increased with time and decreased with age (P<0.01). The ratio of OPG/RANKL initially decreased, increased with time, and then continued to rise with age (P<0.01). CONCLUSIONS Aging could increase the expression of OPG and the ratio of OPG/RANKL and decrease the expression of RANKL in HPDLCs under continuous static pressure in vitro.
Humans ; Adolescent ; Young Adult ; Adult ; Osteoprotegerin ; RANK Ligand/pharmacology* ; Periodontal Ligament/metabolism* ; Cells, Cultured ; Aging