Effectiveness of composite cure associated with different light-curing regimes

This study investigated the use of various light-curing regimens with standardized light energy density on the effectiveness of cure of a visible light activated resin composite (Z100, 3M-ESPE). A light-cure unit (Variable Intensity Polymerizer (VIP), BISCO Inc) which permitted individual control over time and intensity, was used. The five light-curing modes investigated include Pulse Delay (PD), Pulse Cure (PC), Soft-start (SS), Turbo (T) and Control (C). Effectiveness of cure was established by measuring the top and bottom Knoop hardness of 2-mm thick composite specimens using a digital microhardness tester (n=5, load=500g; dwell time=15 seconds) immediately and at one-day post-polymerization. Data obtained was analyzed using one-way ANOVA/Scheffe's post hoc test and Independent Samples t-tests (p<0.05). Top KHN observed immediately after polymerization with C was significantly lower than PD. At one day post-polymerization, the top KHN obtained with C was significantly lower than PD, SS and T. No significant difference in bottom KHN was observed among the different curing modes immediately after curing. At one day post-polymerization, the bottom KHN obtained with C was significantly lower than SS and T. Regardless of curing regimens, top and bottom values at one day were significantly higher than those observed immediately after light polymerization. No significant difference in mean hardness ratio was observed among the different curing regimens immediately and one day later. Effectiveness of the cure at the bottom surfaces of composites may be increased by soft-start and turbo polymerization regimens.     

Antimicrobial effect of triclosan and triclosan with Gantrez on five common endodontic pathogens

Microbial control of the root canal system is one of the key objectives of root canal therapy. Triclosan is a widely accepted broad spectrum antimicrobial agent proven to be effective against many gram-positive and gram-negative bacteria. Triclosan acts by blocking bacterial fatty acid biosynthesis. The addition of Gantrez copolymer has been shown to enhance the antimicrobial activity of triclosan. The purpose of this study was to determine the minimum inhibitory and bactericidal concentrations of triclosan and triclosan with Gantrez against Prevotella intermedia, Fusobacterium nucleatum, Actinomyces naeslundii, Porphyromonas gingivalis, and Enterococcus faecalis. The minimum inhibitory concentration (MIC) of both test solutions was determined for each of the 5 microorganisms by using microtiter serial dilutions. Samples were streaked on 5% sheep blood agar plates and placed in an anaerobic incubator to determine the minimum bactericidal concentration (MBC). The MBC of triclosan ranged from 12-94 microg/mL. The MBC of triclosan with Gantrez ranged from <0.3-10.4 microg/mL. The addition of Gantrez enhanced the bactericidal activity of triclosan. Both triclosan and triclosan with Gantrez demonstrated bactericidal activity against the 5 specific endodontic pathogens.     

Concurrence of replicative senescence and elevated expression of p16(INK4A) with subculture-induced but not calcium-induced differentiation in normal human oral keratinocytes

Primary normal human oral keratinocytes (NHOKs) undergo differentiation in the presence of calcium concentrations higher than 0.15 mM in vitro, which is useful in investigating the mechanisms involved in the differentiation of epithelial cells. Serial subculture of NHOKs to the postmitotic stage also induces terminal differentiation. However, the detailed mechanisms of both differentiation processes remain substantially unknown. To investigate the molecular differences in these processes, NHOKs were induced to differentiate by exposure to 1.2 mM of calcium and by serial subculture to the postmitotic stage. To study whether the cells were induced to differentiate and to undergo replicative senescence, the amount of cellular involucrin and the expression of senescence-associated beta-galactosidase (SA-beta-gal) were measured respectively. The expression of replicative senescence-associated genes and the activity of telomerase from the differentiated cells were also determined. Both calcium treatment and serial subculture to the postmitotic stage notably elevated the cellular involucrin. The percentage of SA-beta-gal-positive cells was significantly elevated by the continued subculture, but such changes were not observed in keratinocytes exposed to calcium. The concentration of cellular p16(INK4A) protein was progressively increased by the continued subculture but was not changed by calcium treatment. On the other hand, the concentrations of cellular p53 were similar in both differentiation processes. However, telomerase activity was lost in NHOKs that had undergone differentiation by both calcium treatment and serial subculture. The results indicate that calcium-induced differentiation of NHOKs has similar characteristics to their serial subculture-induced differentiation, but that the differentiation processes are not identical, because calcium-induced differentiation does not concur with either replicative senescence or the gradually increased concentration of p16(INK4A).     

茶多酚对+Gz过载的颞下颌关节影响分析

目的：观察茶多酚对持续性高正加速度（＋Gz）加载颞下颌关节的影响。方法：雄性Wistar大鼠随机分成5个不同处理条件的实验组，每组12只。A组为空白对照。B组地面固定5min。C 固定于离心机转臂上，俯卧位，头向轴向，＋Gz离心5min。D组体位同C组，＋10Gz离心30s，间隔时＋1Gz离心60s，连续每天5次，每周4天，共3周，E组实验参数同D组，并于＋Gz离心前1h灌胃给予茶多酚（200mg.kg^-1)，其余各组给予等量蒸馏水，通过光镜，扫描和透射电镜观察比较组颞下颌关节的组织形态学变化情况，结果：A、B、C三组颞下颌关节未见异常；D组颞下颌关节表面凝胶状物质缺失，胶原纤维断裂，成纤维细胞线粒体变性；E组颞下颌关节表面凝胶状物质变薄但完整，胶原纤维断裂，成纤维细胞线粒体较正常，结论：茶多酚能在一定程度上保护凝胶状物质和成纤维细胞来对抗持续性高正加速度对颞下颌关节的损伤。     

The position of the apical foramen of the permanent incisors

The position of the apical foramen in relation to the anatomical root apex is of considerable importance to the dentist, especially when the level of obturation of the root canal is determined through tooth length calculated radiologically. The main objective of this study was to determine in upper permanent incisor teeth, the position of foramen/foramina relative to the anatomical apex.
In 635 permanent upper incisors, the results of this study showed 54.3 per cent with the foramen coincident with the root apex, and 45.7 per cent where the root apex and the foramen were non-coincident. The average distance of the foramen from the root apex in the latter group was 0.35 mm and it ranged from 0.1 to 1.2 mm. The significance of these findings is discussed in relation to the apical termination of debridement and obturation of root canals.     

应用牵张成骨技术行牙槽嵴增高术的研究进展

牵张成骨 (distractionosteogenesis,DO)指在骨缝处或在截开的骨段用牵张装置按一定的速度和频率牵开 ,因此产生的骨间隙中形成新骨 ,从而达到使骨延长或增宽的目的。该技术用于四肢长骨已有近百年历史 ,在颅面部治疗颌骨缺损、畸形及阻塞性睡眠呼吸暂停综合征等领域也获得了成功。近年来 ,用牵张成骨技术增高牙槽嵴逐渐成为研究热点 ,现综述如下。一、牵张成骨技术与传统牙槽嵴增高术的比较牙槽嵴增高术分相对增高及绝对增高两种 ,前者指唇颊沟加深或牙槽嵴延伸术 ,后者指牙槽嵴增高术。唇颊沟加深术通过改变黏膜及肌附着的位置 ,使牙槽嵴…     

Expression and possible immune-regulatory function of ghrelin in oral epithelium

Originally found in stomach mucosa, ghrelin is a peptide appetite hormone that has been implicated as an immuno-modulatory factor. Ghrelin has also been found in salivary glands and saliva; however, its expression patterns and biological properties in the oral cavity remain unclear. Therefore, we investigated the expression patterns of ghrelin in saliva, gingival crevicular fluid (GCF), and gingival tissue, as well as its in vitro effects on IL-8 production by TNF-α or LPS-stimulated oral epithelial cells. In the clinical samples obtained from 12 healthy volunteers, the concentration of ghrelin in GCF remarkably exceeded that detected in saliva. The expression of ghrelin mRNAs and growth hormone secretagogue (GHS) receptors could be detected in human oral epithelial cells. Immunohistochemical analysis revealed the expression of ghrelin in gingival epithelium, as well as in fibroblasts in the lamina propria. Ghrelin increased intracellular calcium mobilization and cAMP levels in oral epithelial cells, suggesting that ghrelin acts on epithelial cells to induce cell signaling. Furthermore, synthetic ghrelin inhibited the production of IL-8 from TNF-α or LPS-stimulated oral epithelial cells. These results indicate that ghrelin produced in the oral cavity appears to play a regulatory role in innate immune responses to inflammatory infection.