Comparason of the clinical efficacy of different gingival retraction methods / 实用口腔医学杂志

Objective: To evaluate the effects of 4 gingival retraction methods. Methods: 48 premolars were selected from 12 periodontal healthy volunteers and were randomly divided into 4 groups(n = 12 teeth) and treated with different gingival retraction methods: Ultrapak E(group UL) and three kinds of cordless gingival retraction, including Expasy1 (group EX), Astringent Retraction Paste (group AS) and Racegel(group RA). Perfusing plaster models were prapaired after useing putty-wash impression technique. A 3D digital model was reconstructed by a 3-shape model scanner for each patient. Data were collected before and after gingival retraction and analysed by the Geomagic Studio 2013 in the mesial, middle, and distal sides of the selected teeth. Results: Effective width of gingival retraction were all obtained in the 4 groups. The most effective effects were observed in group UL, followed by group EX, group AS and group RA, among the groups, F = 1 114. 4, P＜ 0. 000 1. Conclusion: Cordless gingival retraction technic can achieve effective gingival retraction.

Effect of dentin proteoglycans on the stability of resin-dentin bonds against artificial saliva storage / 中华口腔医学杂志

Objective@#To investigate the potential effect of proteoglycans (PG) and glycosaminoglycans (GAG) on the stability of resin-dentin bonds against artificial saliva storage.@*Methods@#Seventy-two extracted molars were used to obtain standard dentin bonding surface, and the specimens were etched for 15 s with 37% phosphoric acid and divided into three groups using a table of random number. Then the three groups undergone different incubating procedures as follow: specimens in chondroitinase ABC (C-ABC) group were incubated with C-ABC, specimens in trypsin (TRY) group were incubated with trypsin, and specimens in the control group were incubated with deionized water. All specimens were incubated at 37 ℃ for 48 h in the oscillators. Then specimens in each group were randomly assigned into three subgroups (n=8) as follows: immediate control subgroup, aging subgroups with artificial saliva storage for 6 months and 12 months. Microtensile bond strength (μTBS), fracture mode, bonding interface morphology and nanoleakage were evaluated.@*Results@#Immediately and with artificial saliva storage for 6 months and 12 mouths, the μTBS of TRY group ([49.04±3.57], [37.01±3.21] and [35.27±3.56] MPa) were significantly higher than those in the control group ([40.71±3.32], [28.87±2.34] and [24.20±2.07] MPa) (P<0.05). The immediate μTBS of C-ABC group ([32.94±2.45] MPa) was significantly lower than that of the control group (P<0.05). While with artificial saliva storage for 6 months and 12 mouths, the μTBS of C-ABC group ([26.46±2.45] and [22.50±2.58] MPa) were no differences with those of the control group (P>0.05). The ratio of cohesive fracture increased with the extension of aging time. Some narrow gaps were found in hybrid layer of the control group with artificial saliva storage for 6 months and 12 mouths.@*Conclusions@#Removal of PG increased the μTBS and durable bonds to dentin, while removal of GAG decreased the μTBS, however, it can be of help to create more durable bonds to dentin.

New fixation set-up designed for micro-tensile test / 实用口腔医学杂志

Objective:To introduce a new fixation set-up for micro-tensile test.Methods:Dentin-composite were bonded with AdperTM Single Bond 2 (SB2)and sectioned into stick-shaped specimens.Specimens from each tooth(n =6)were equally divided into Ciucchi's jig and the designed set-up(Control and experimental)groups for micro-tensile bond test according to the utilized fixa-tion set-up.The bonding interface failure mode was examined with field-emission scanning electron microscope (FESEM).Three-dimensional models of the two set-ups and the specimen were developed,stress distribution was analyzed by finite element analysis (FEA).Results:The bond strength(MPa)of experimental and control group was 32.76 ±7.43 and 43.58 ±4.72(P <0.05),the ratio of mixed failure was 28 /36 and 20 /36(P <0.05)respectively.FEA showed that the designed set-up for fixing the sticks pro-vided a uniform stress distribution along the long axis of the specimen.FEA and failure mode analysis confirmed such uniform distri-bution was also concentrated at the bonding interface.Conclusion:The new set-up is feasible for micro-tensile test.

Analysis of type-I collagen fibrils and chondroitin sulfate distribution in human dentin by confocal laser scanning microscopy combined with dual immunofluorescent labeling technique / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To introduce the method of dual immunofluorescence labeling of human dentin matrix without demineralization of the whole dentin fragments, and to analyze the distribution of type-I collagen fibrils and chondroitin sulfate in human dentin.</p><p><b>METHODS</b>Forty 30 µm- thick middle coronal dentin sections were obtained from 8 freshly extracted human third molars and etched with 37% phosphoric acid(PA) gel for 15 s. After preconditioning with or without tosyl- phenylalanyl chloromethyl ketone(TPCK) treated trypsin digestion, sections were subjected to dual immunofluorescent labeling and scanned by confocal laser scanning microscopy to identify the type-I collagen fibrils and chondroitin sulfate.</p><p><b>RESULTS</b>Chondroitin sulfate was localized in the lumens of the dentin tubules and peritubular dentin, while the type-I collagen fibrils were localized in intertubular dentin and peritubular dentin. After preconditioning with TPCK treated trypsin digestion, the red fluorescence was decreased or disappeared.</p><p><b>CONCLUSIONS</b>The dual immunofluorescence labeling methodology can be used to study the human dentin matrix without demineralization of the whole dentin fragments. Chondroitin sulfate was localized in the lumens of the dentin tubules and peritubular dentin, while the type-I collagen fibrils were localized in intertubular dentin and peritubular dentin.</p>

Effect of dentin proteoglycans on the bonding properties of dentin / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the potential effect of proteoglycan (PG) and glycosaminoglycan (GAG) on the bonding of etch and rinse adhesive to dentin, in order to improve the bonding effect of dentin.</p><p><b>METHODS</b>Forty-two extracted molars were used to obtain standard dentin bonding surface, and the specimens were etched for 15 s with 37% phosphoric acid and divided into three groups using a table of random numbers. Then the three groups undergone different incubating procedures as follow: specimens in chondroitinase ABC (C-ABC) group were incubated with C-ABC at 37 °C for 48 h in vibrator. Specimens in trypsin (TRY) group were incubated with trypsin, and specimens in the control group were incubated with deionized water for 48 h in the oscillators. Then specimens in each group were randomly assigned into two subgroups, A (Adper(TM) Single Bond 2) and B (Prime & Bond NT) (n = 7). The microtensile bond strength (µTBS), fracture mode and bonding interface morphology of the specimens were evaluated via microtensile testing, stereo microscope and field emission scanning electron microscopy (FE-SEM) respectively after specimens being incubated in 37 °C water for 24 h.</p><p><b>RESULTS</b>The immediate µTBS of C-ABC group bonding with adhesive A and B [(32.9±2.5) and (26.8±2.2) MPa] were significantly lower than that of the control group [(40.7±3.3) and (34.6±3.7) MPa] (P < 0.05). While the immediate µTBS of TRY group [(49.0 ± 3.6) and (44.5 ± 3.0) MPa] were significantly higher than that of the control group(P < 0.05).</p><p><b>CONCLUSIONS</b>Dentin PG participates in the dentin bonding process. Removal of PG increased the immediate µTBS of dentin and total etching adhesives, while removal of GAG decreased the immediate µTBS.</p>

Bonding properties of four different cements to glass fiber posts after different treatments / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of four different cements on the bonding effectiveness of root canal dentine and fiber post before and after different treatments.</p><p><b>METHODS</b>A total of 216 freshly extracted sound single-root-canal mandibular premolars were randomly divided into four groups. After root canal treatment and post space preparation being conducted on the premolars, Fuji I, Fuji Cem, RelyX Unicem, RelyX ARC were used respectively to bond fiber posts and were marked with group A, B, C, and D. Microleakage, micromorphology of the bonded interfaces, and pull-out bond strength were evaluated in the immediate group, thermocycling group and thermomechanical loading group.</p><p><b>RESULTS</b>In the immediate group, samples in group D showed the highest bond strength [(278 ± 26)N], followed by group C[ (219 ± 12) N], B[ (104 ± 23) N] and A[(73 ± 8) N]. Significant differences were found among all groups (P < 0.05) . A significant increase in bond strength was found in group A and B, whereas a decrease tendency was detected in group C and D after different treatments.Scanning electron microscope indicated that some little gaps were observed in group D after treatment, while a more intense bonding interface was found in group A and B. Microleakage scores in group A and B were lower than those in group C and D after aging treatments.</p><p><b>CONCLUSIONS</b>Resin cement can achieve a better immediate bond strength, while resin-modified resin cement may acquire a better long-term retention.</p>

Effects of acid etching time on nanoleakage and microtensile bond strength of the adhesive-dentin bond / 实用口腔医学杂志

Objective: To observe the effects of acid etching times on nano-leakage and microtensile bond strength(?TBS) of the 4 total-etching adhesives-dentin bond.Methods: Superficial occlusal dentin surfaces of 80 molars were prepared with 600-grit SiC paper under running water.4 adhesives were applied to dentin surfaces under different etching time.The bonded teeth were sectioned occluso-gingivally into 1.0 mm?1.0 mm?4.0 mm serial slabs which were prepared for TEM and ?TBS tests.Results: Under 15 s etching time for 4 adhesives,the highest ?TBS(OB(25.36?4.18) MPa,SB(24.25?3.97) MPa,OS(28.65?4.93) MPa,PB(27.12?4.13) MPa) were achieved,and the amount of nanoleakage was positively correlated with the length of etching time.Conclusion: Etching for a reasonable time demineralizes the dentin surface to a moderate depth,resulting in higher ?TBS and lower nanoleakage.

Evaluation of 4 dentin adhesives in vivo / 实用口腔医学杂志

Objetives: To evaluate the microtensile bond strengths o f four dentin adhesives (Single Bond, Bond-1, Prime&Bond NT and One-Step) i n vivo.Methods: Before extraction the superficial occlu sal dentin of 19 molars (because of severe periodontitis) in 17 volunteers was exposed by diamond bur of a high-speed hand-piece copious air-water spray under local anesthesia, the crown was bonded with one of the above adhesives a ccording to the manufacturers' instructions. The teeth were then extracted and kept in normal saline for 24 h under 37 ℃,sectioned to obtain two or three bar -shaped specimens, which were then shaped to an hour-glass form. The specimens were stressed until rupture of the bond. The mean bond strength of the adhesive s was measured and compared using student test. Rusults: M ean microtensile bond strength (MPa) of Single Bond,Bond-1,One-Step and Prime & Bond NT to the tooth surface was 26.18?3.67,30.08?3.15,29.91?3.51,29.70?3 .03 respectively (P

Restoration of multiple residual roots and crowns with the zirconia all-ceramic crown/bridge:A clinical report / 实用口腔医学杂志

Based on the properties of the zirconia all-ceramic material,this report presented a clinical application with the zirconia all-ceramic crown/bridge for restoration of multiple residual roots and crowns.