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15 June 2013, Volume 6 Issue 6 Previous Issue    Next Issue

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Dental digital impression XU Ming-ming， LIU Feng 2013, 5(6): 321-326.  Abstract ( )   PDF (1038KB) ( )   Abstract：Dental digital impression has developing quickly with the CAD/CAM technology. Compared with model scanning， digital impression is much more complicated and much dependent to the system. There are several dental digital impression systems including CEREC Bluecam （Sirona， Germany）， CEREC Omnicam （Sirona， Germany）， Lava C.O.S. （3M， USA）， iTero （Cadent/Straumann， USA）， E4D （E4D， USA），with different principles and dominance. Digital impression has better application according to the efficiency， accuracy and comfort， but should be noticed on tooth preparation， drying， wet insulation， shading powder and image taking.

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Rapid prototyping technology and its application in prosthodontics CHEN Xiao-dong， XING Wen-zhong 2013, 5(6): 326-330.  Abstract ( )   PDF (957KB) ( )   Abstract： Rapid prototyping （RP） technology is a technology through which the complex-shaped 3D physical models could be rapidly fabricated directly from computer-aided design （CAD） models. In comparison with the traditional technology， RP technology is much less time-consuming， able to allow the fabrication of many complex parts， and therefore widely employed in manufacturing sector. It is now taking an increasingly wider application in dentistry， especially in prosthodontics. The fabrication of prosthesis through RP technology is regarded as a promising alternative for dental prosthesis production. In this article， we review the most commonly applied RP techniques in prosthodontics and restorative dentistry， the fabrication of prosthesis and its effect.

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Application status of CAD/CAM systems and machinable materials in prosthodontics ZHAO Xin， ZHAN De-song 2013, 5(6): 331-337.  Abstract ( )   PDF (1025KB) ( )   Abstract：With the patients' increasing demand for aesthetics and biocompatibility of prosthesis and with the development of high strength machinable materials， CAD/CAM systems have been widely used for its high efficiency and accuracy. This article provides the overview of present clinical application of CAD/CAM systems and machinable materials in prosthetics.

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The application of chairside CAD/CAM system to minimally invasive esthetic restoration YANG Jian 2013, 5(6): 337-341.  Abstract ( )   PDF (941KB) ( )   Abstract： The introduction of new adhesive materials and techniques have led to the development of minimal invasive dentistry. CAD/CAM systems are also widely used in the dentistry nowadays. The objective of this article is to discuss the clinical issues about how to improve the esthetic and longevity of the machinable glass-ceramic restorations fabricated with chairside CAD/CAM system in minimally invasive dentistry.

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A review of dental CAD/CAM and its application LU Zhen-fu， LI Jian 2013, 5(6): 342-345.  Abstract ( )   PDF (927KB) ( )   Abstract： Computer-aided design and computer-aided manufacturing （CAD/CAM） is an oral repair technology which combines with optoelectronic technology， computer technology and numerical control machining technology. With the rapid development of computer technology， the use of CAD/CAM in oral clinical application is becoming more and more wide. Now， the most commonly used system is CEREC， EVEREST， PROCERA， CERCON， and UPCERA. In this review， we summarized the structure and principle and cutting materials of each system.

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Experimental study on the expression of BMP-2 in rat pulp during direct pulp capping with Dycal and MTA ZHANG Xiao-fang， KANG Hong-ying， YAO Ya-peng， DONG Pei 2013, 5(6): 346-349.  Abstract ( )   PDF (1616KB) ( )   Abstract： Objective To observe the expression of bone morphogenetic protein-2 （BMP-2） in rat pulp after direct pulp capping with Dycal and mineral trioxide aggregate（MTA）. Methods Samples from 42 Wistar rats were collected at12 h，1， 3， 7， 14， 21 and 28 days after direct pulp capping with Dycal and MTA. Pulp tissues were studided with immunohistochemical stain. Software for image analysis was used to test the optical density of each specimen. The data were analyzed by paired t-test and Dunnett-t test with SPSS 13.0. Results In normal pulp， the stain of BMP-2 was negative，the staining of BMP-2 in low level expression at 12 hours increased gradually， reached the peak at 7days，and after 14 days the stain became less positive gradually till after 28 days it approached to normal.The reparative dentin in the group of MTA was more than the Dycal group.Expression of BMP-2 in the group of MTA was significantly higher than Dycal group at 7 days and14 days after direct pulp capping. Conclusion After direct pulp capping with MTA，the reparative dentin is more than Dycal；the expression of BMP-2 is significantly higher than MTA at 7 days and 14 days；MTA may be involved in the induction of reparative dentin formation by regulating the expression of BMP-2；BMP-2 expression intensity may affect pulp repair.

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Meta analysis of Orwell desensitization agent in treatment of dentin hypersensitivity DONG Xiao-yu*， HE Shuai，ZHU Zu-feng 2013, 5(6): 350-355.  Abstract ( )   PDF (2169KB) ( )   Abstract：Objective To assess the effectiveness and safety of Orwell desensitization agent in treating dentin hypersensitivity by Meta analysis. Methods CNKI，CBM，Chinalnfo and VIP database were searched in PC to collect the RCT trials about the treatment of Orwell desensitization agent for dentin hypersensitivity. Quality of the trials was evaluated， and the data was analyzed by Meta-analysis.Meta-analysis was performed for the results of homogeneous studies by RevMan 5.2 software. Results Six trials including 543 cases （totally 780 teeth） were studied. The Meta analysis result of the instantly efficacy of Orwell desensitization agent for dentin hypersensitivity was that the RR value was 1.28， 95% CI（1.13，1.45）， and P < 0.0001. The Meta analysis result of 1 month efficacy of Orwell desensitization agent for dentin hypersensitivity was that the RR value was 1.26， 95% CI（0.94，1.71）and P=0.13＞0.01. Analysis result of 2 months efficacy of Orwell desensitization agent for dentin hypersensitivity only included the study of CHENG Xiu-hui and P = 0.08>0.01. The Meta analysis result of 3 months efficacy of Orwell desensitization agent for dentin hypersensitivity was that the RR value was 1.39， 95% CI（1.11，1.73）， and P = 0.004<0.01.The Meta analysis result of 6 months efficacy of Orwell desensitization agent for dentin hypersensitivity is that the RR value was 2.14， 95% CI（1.77，2.60）， and P < 0.00001. Conclusion The effect of Orwell desensitization agent on dentine hypersensitivity is better than 75% sodium fluoride glycerin in instant efficacy，1 month，3 months and 6 months. But it is not enough to draw this conclusion in 1 months and 2 months efficacy.

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Comparison between conventional and self-ligating brackets on testing the resistance to sliding DU Rui， FENG Yun-xia 2013, 5(6): 356-359.  Abstract ( )   PDF (1140KB) ( )   Abstract：Objective To investigate the difference and the laws of variation on the resistance to sliding of conventional and self-ligating brackets. Methods A maxillary simulation model with pericementum was set up according to the proportion of somatological elastic modulus. The resistance to sliding was measured by conventional brackets and self-ligating brackets and the arch wire of 0.016 and 0.018 inches NiTi wires and 0.017×0.022、0.018×0.025、0.019×0.025 inches stainless steel wires. Results The resistance to sliding was followed from the high to the low: Damon Q passive self-ligating brackets < Tomy active self-ligating brackets < conventional brackets， and the differences were significant （P < 0.05）； The resistance to sliding increased along with the increase of the diameter of archwires， except that the resistance to sliding of the 0.019×0.025 inch rectangular archwire was lower than the 0.017×0.022 and 0.018×0.025 inch ones. The differences between them were significant （P < 0.05）. Conclusion Clinically the resistance to sliding is influenced by the match of different types of brackets and the arch wire， which is important in realizing the rapid and effective movement of teeth.

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Comparative study of the apical sealing ability of three canal obturation techniques WANG Miao*，WU Hong-bin， SONG Xue-lian，CHEN Qing，BI Xin-xin，YU Jing-tao 2013, 5(6): 360-363.  Abstract ( )   PDF (887KB) ( )   Abstract：Objective To compare and evaluate the sealing ability of three canal obturation methods. Methods Thirty-four single-canal extracted teeth were cleaned the root canal and shaped using the Pro-Taper Ni-Ti rotary instruments with the Crown-Down technique. All teeth were randomly divided into three groups：Group A （11 teeth） were obturated with the cold lateral condensation technique；Group B （10 teeth） were obturated with the ultrasonic lateral condensation technique；Group C （13 teeth） were obturated with the continuous-wave of gutta-percha vertical condensation technique. All the teeth were given the same sealer （AHPlus）.The leaked condition of the apical was measured by dye infiltration test. Linear dye penetration was measured under stereo microscope with calibrated eye piece from the apical to crown of the teeth， and the results analyzed. All measurements were analyzed by SPSS11.5 software. Results The length of apical dye penetration showed significant difference between Group A and B and between Group A and C（P＜0.01）. There was no significant difference between Group B and C（P＞0.05）. Conclusion The ultrasonic lateral condensation technique and the continuous-wave of gutta-percha vertical condensation technique are better than the cold lateral condensation technique with gutta-percha，and the first two root canal filling techniques have no significant difference in sealing ability.

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Study of bonding strength of two different resin adhesive system FANG Tie-jun， CHEN Wei，DI Li-sha， WU Shao-mei 2013, 5(6): 364-366.  Abstract ( )   PDF (970KB) ( )   Abstract： Objective To evaluate the bonding strength of fiber posts cemented to root canals of two resin adhesive systems， as well as the bonding strength between two resin adhesive systems. To offer the rational selection on how to get the best bonding strength when using the resin adhesive systems in post-cores restoration during clinical practice. Methods A total of 30 second premolars which were simple root canal with similar shape and size were selected.The teeth were randomly devided into 3 groups after endodontic treatment，10 samples in each group.Luxacore and 3M Unicem resin were used respectively and at the same time to bond fiber-posts.The roots were cut into 2.0 mm-thick sections；all the sections were tested by push-out test which was performed with a universal testing machine.The bonding strength values were compared，and fracture modes of interface were observed using stereomicroscope. Results significant differences existed among 3 groups. There was statistically significant difference between group C and group A，as well as group C and group B（P＜0.05），but no significant difference between group A and group B（P＞0.05）.The major fracture mode of group A and B was bonding failure between cements and dentine，but on the other side，fracture mode of group C was almost the bonding failure between two cements. Conclusion The bonding strengths between two cements are lower than either one’s bonding strength which cement to dentine or fiber-posts.

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Effects of immediate or delayed post space preparation on apical microleakage after root canal obturation of different lengths BAI Xue*， REN Guo-heng，JIANG Zhi-qing 2013, 5(6): 367-369.  Abstract ( )   PDF (849KB) ( )   Abstract： Objective To explore the effects of immediate or delayed post space preparation on apical microleakage after root canal obturation of different lengths. Methods Totally 120 extracted human teeth with single root were randomly assigned to 6 groups. The 5mm long apical root was filled after root preparation in group A and the whole root was filled in group B. The post space was prepared either immediately after root canal obturation （groups A1 and B1） or one week later （groups A2 and B2）. For groups A3 and B3， no post space preparation was carried out. Indian ink dye and transparency methods were adopted and the extent of dye penetration was measured under a stereo microscope. Results No statistically significant differences were detected between groups A and B （P > 0.05）. There were no significant differences between groups A1 and A3 or B1 and B3 （P > 0.05）. But there were significant differences between the above groups and groups A2 or B2 respectively （P < 0.05）. Conclusion Different lengths of root filling have similar effects on apical microleakage. Delayed post space preparation leads to more serious apical microleakage than immediate post space preparation.

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Research progress of temporomandibular joint post-traumatic osteoarthritis and its pathogenesis SUN Yu-huan，HE Dong-mei 2013, 5(6): 370-374.  Abstract ( )   PDF (908KB) ( )   Abstract： Temporomandibular joint （TMJ） post-traumatic osteoarthritis （PTOA） is defined as progressive articular cartilage degeneration caused by trauma. Clinical manifestations are persistent pain which could radiate to neck and shoulder muscles， joint clicking or crepitus， limitation of mouth opening and weakness of chewing. Pathology shows loss of articular cartilage， osteophyte formation and subchondral bone sclerosis. The current treatment is mainly drugs administration to relieve pain and artificial joint replacement for advanced lesions. There is still a lack of effective medication to stop or even reverse the progression in the early stage of PTOA. In order to look for effective targets it is necessary to understand the pathogenesis. TMJ PTOA and its pathogenesis research progress were reviewed in this article.

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Oral appliances in the treatment of obstructive sleep apnea syndrome WANG Jie-rui， MI Cong-bo 2013, 5(6): 375-378.  Abstract ( )   PDF (874KB) ( )   Abstract： Obstructive sleep apnea syndrome is commonly observed in clinics. Many cases present a significant health risk and can result in excessive daytime sleepiness， early morning headaches， impaired concentration， hypertension， heart disease， cerebrovascular disease，or even death. The method of treatment for obstructive sleep apnea syndrome is developing fast. Oral appliances have been used by dentists for several decades to treat snoring and obstructive sleep apnea syndrome due to its uniqueness. The purpose of this article is to review the types and efficacy of oral appliances， the mechanisms of oral appliances and to summarize their clinical effectiveness and side effects.

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The mechanism of apoptosis mediated by ERS and the role of ERS in the dental fluorosis MA Lin， ZHANG Ying， ZHANG Kai-qiang， GU He-feng 2013, 5(6): 379-382.  Abstract ( )   PDF (878KB) ( )   Abstract： Endoplasmic reticulum（ER）is an important organelle of eukaryotic cells. ER will produce a series of regulatory mechanism under some stimulus， collectively called endoplasmic reticulum stress. Endoplasmic reticulum stress can accumulate unfolded or misfolded proteins in the ER，which affect the balance of Ca2+. To resolve cellular damage，the ER triggers the unfolded protein response to maintain ER homeostasis .However， the apoptosis will occur with increasing stimulus and time of exposure .Too much apoptosis can also cause disease. Dental fluorosis is caused by inhibiting protein secretion and/or synthesis，so we infer that endoplasmic reticulum stress may be responsible for dental fluorosis. This paper reviewed the mechanism of endoplasmic reticulum stress effects on cells， and their possible mechanisms of involvement in dental fluorosis.

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2013, 5(6): 383-384.  Abstract ( )   PDF (842KB) ( )