牵张应变作用下人牙周膜细胞内磷脂酶C-γ1水平的变化

目的:观察机械牵张应变作用下,人牙周膜细胞(HPDLCs)内磷脂酶C-γ1(PLC-γ1)水平的变化。方法:通过原代和传代培养,获得性状稳定的人牙周膜细胞,使用动态机械应变细胞加载仪对细胞进行1%、10%和20%动态牵张应变加载。加载不同时间,通过流式细胞仪对细胞进行PLC-γ1水平检测。采用SPSS13.0软件包对数据进行方差分析。结果:在加载牵张应变初期,细胞内的PLC-γ1水平维持较低水平;随着牵张应变加载时间的延长,牙周膜细胞内的PLC-γ1水平逐渐升高。50min时,PLC-γ1水平达到各应变组的最高值(P<0.01)。随着加载时间的继续延长,60min时,各应变组的PLC-γ1水平都显著下降(P<0.01)。结论:牵张应变可引起细胞内PLC-γ1水平的变化。     

PBL core skills faculty development workshop 1: An experiential exercise with the PBL process

This report describes the first in a series of foundation-building faculty development workshops focused on the instructional methodology of problem-based learning (PBL). The PBL Process workshop reported here introduced the learning theory topics supporting PBL and utilized an extended roleplay method to provide participants with personal experience with the PBL learning cycle. Overall, participants were satisfied with the methods and content of the workshop. A majority of survey respondents indicated that simulating a complete iteration of the PBL process was an effective way to learn about PBL. Participants expressed relatively greater difficulty understanding and performing activities related to qualitative assessment of learning processes. The workshop was developed to align with adult learning principles, and continued refinement of the workshop has enhanced the learning theory components underpinning PBL as well as the experiential aspects. These dual goals have resulted in blending the existing experiential workshop with an online distance-learning component addressing the learning theory topics relevant to PBL pedagogy.     

Age,period, and cohort analysis of regular dental care behavior and edentulism: A marginal approach

Background

Microbial communities inhabiting human mouth are associated with oral health and disease. Previous studies have indicated the general prevalence of adult gingivitis in China to be high. The aim of this study was to characterize in depth the oral microbiota of Chinese adults with or without gingivitis, by defining the microbial phylogenetic diversity and community-structure using highly paralleled pyrosequencing.

Methods

Six non-smoking Chinese, three with and three without gingivitis (age range 21-39 years, 4 females and 2 males) were enrolled in the present cross-sectional study. Gingival parameters of inflammation and bleeding on probing were characterized by a clinician using the Mazza Gingival Index (MGI). Plaque (sampled separately from four different oral sites) and salivary samples were obtained from each subject. Sequences and relative abundance of the bacterial 16 S rDNA PCR-amplicons were determined via pyrosequencing that produced 400 bp-long reads. The sequence data were analyzed via a computational pipeline customized for human oral microbiome analyses. Furthermore, the relative abundances of selected microbial groups were validated using quantitative PCR.

Results

The oral microbiomes from gingivitis and healthy subjects could be distinguished based on the distinct community structures of plaque microbiomes, but not the salivary microbiomes. Contributions of community members to community structure divergence were statistically accessed at the phylum, genus and species-like levels. Eight predominant taxa were found associated with gingivitis: TM7, Leptotrichia, Selenomonas, Streptococcus, Veillonella, Prevotella, Lautropia, and Haemophilus. Furthermore, 98 species-level OTUs were identified to be gingivitis-associated, which provided microbial features of gingivitis at a species resolution. Finally, for the two selected genera Streptococcus and Fusobacterium, Real-Time PCR based quantification of relative bacterial abundance validated the pyrosequencing-based results.

Conclusions

This methods study suggests that oral samples from this patient population of gingivitis can be characterized via plaque microbiome by pyrosequencing the 16 S rDNA genes. Further studies that characterize serial samples from subjects (longitudinal study design) with a larger population size may provide insight into the temporal and ecological features of oral microbial communities in clinically-defined states of gingivitis.     

The origins of fear of occupational exposure in the clinical dental setting

Although there is a growing literature on the incidence of occurrence and reporting of occupational exposures in clinics in dental schools, the contributing factors to fear of such injuries and their dynamic evolution over time remain unstudied. It is hypothesized that fear of occupational exposures is a function of estimated likelihood of such events and their perceived importance. Individual personality factors and situational circumstances are also thought to play a role, although it is believed that these factors recede in importance as students gain direct knowledge through clinical experience. Path analysis methods are applied to longitudinal survey data in a single dental school to confirm these hypotheses.     

Identification of caries risk factors in toddlers

The purpose of this study was to identify risk factors to predict caries progression in toddlers in primary-healthcare settings for the cost-effective targeting of preventive and referral strategies. We examined 329 children (26 ± 6 mos old) twice, one year apart, in Indiana, USA. A 107-item structured interview was used to collect information from the primary caregiver and child on factors/beliefs/perceptions/behaviors that could affect caries development, transmission of bacteria, medical-dental health, and access to care. Bacterial levels, gingivitis, dental plaque, and caries experience were assessed. Multiple-variable logistic regression models of caries progression toward cavitation included family caries experience, transmission-related behaviors, dietary factors, health beliefs, and lower income, but differed in selected predictors/predictive power by race/ethnicity. Addition of clinical variables did not significantly improve the prediction.     

Serum mepivacaine concentrations after intraoral injection in young children

The authors measured plasma concentrations of mepivacaine in 36 children from the ages of 2 to 5 years who received dental care under light general anesthesia. The subjects were randomly assigned to receive either 2 percent mepivacaine hydrochloride with 1:20,000 levonordefrin or 3 percent mepivacaine hydrochloride without vasoconstrictor. The volume of anesthetic injected depended on the planned procedures for each patient. Blood samples (3 mL) were drawn from an intravenous line before and 5, 10, 20, 30, 45, and 60 minutes after mepivacaine injection. The serum was collected and analyzed by gas-liquid chromatography. Mean serum concentrations, normalized to a dose of 1 mg/kg body weight, reached a peak of 0.67 +/- 0.42 microgram/mL (mean +/- SD) after 3 percent mepivacaine and 0.63 +/- 0.21 microgram/mL after 2 percent mepivacaine with levonordefrin. Levonordefrin had no significant effect on the plasma concentrations. However, because of the higher concentration of mepivacaine in the 3 percent formulation, it was potentially 1.5 times as toxic (P < 0.002) on a volume basis. Statistical analysis also suggested that the maximum recommended dose of 3 mg/lb could result in potentially toxic blood concentrations in a small percentage of pediatric patients. The authors conclude that 3 percent mepivacaine should not be used when relatively large volumes of local anesthetic must be administered to small children and recommend that the maximum dose of mepivacaine not exceed 5 mg/kg.     

Repair of alveolar clefts with recombinant human bone morphogenetic protein (rhBMP-2) in patients with clefts

This article demonstrates the feasibility of using recombinant human bone morphogenetic protein (rhBMP-2) as a substitute for autogenous iliac crest bone for repair of congenital facial clefts in humans. In this series, 50 cleft sites were repaired in 43 patients using rhBMP-2 without the use of autogenous graft tissue. Successful osseous union was achieved in 49 of the 50 sites. In one patient, the graft failed to consolidate. Severe clefts were managed by combining distraction osteogenesis and rhBMP-2. Eliminating the need to harvest autogenous iliac crest bone resulted in substantial decrease in morbidity. The constructed alveolus performed clinically as normal bone and responded to natural tooth eruption and orthodontic movement. Histology of the tissue constructed showed normal, vital bone. Although additional investigation is warranted to determine the optimum protocol for the use of this material in alveolar cleft repair, the technique should be considered as a viable treatment option in cases in which avoiding iliac crest harvesting is desirable.     

应用脱细胞真皮基质修复口腔黏膜缺损22例报道

目的：评价脱细胞异体真皮基质组织补片用于口腔黏膜缺损修复的临床效果。方法：对22例因肿瘤手术、外伤、瘢痕、不良增生物切除术及修复前外科等原因引起的口腔黏膜的缺损,应用脱细胞异体真皮基质口腔组织补片进行修复。缺损部位主要为软硬腭、舌、口底、颊部、牙龈、前庭沟等。使用的口腔组织补片面积为1cm×1cm～4cm×6cm。术后随访1周～6个月。结果：共修复22例口腔黏膜缺损,其中2例患者2周后失访。随访的20例病例中,成活18例,脱落2例。术后补片收缩发生在2～4周。2个月后补片较稳定,未发生进一步挛缩。结论：脱细胞真皮基质作为一种黏膜缺损替代品,应用于口腔内各种原因引起的黏膜缺损修复,效果满意。     

骨移植牙种植体同期植入的扫描电镜观察

目的：探讨骨移植牙种植体同期植入后骨整合的效果。方法：恒河猴6只随机分三组分别行血管吻合骨移植（Vascularized Bone Graft,VBG)牙种植体同期植入；游离骨移植（Non-Vascularized Bone Graft,NVBG)牙种植体同期植入，拔牙后三个月植入牙种植体，切取标本后扫描电镜观察，结果：VBG组：术后12周移植骨与种植体之间部分为骨性结合界面，16周呈完整的骨性结合，NVBG组：术后12周其界面为纤维结缔组织，少量骨少梁，24周大部分为骨性结合界面，呈完整的骨性结合。结论：VBG或NVBG牙种植体同期植入均能形成骨性整合，但NVBG组形成较晚，临床应用中应予注意。