Brain activation patterns during unilateral premolar occlusion

Objective: To observe the characteristics of brain activation during unilateral premolar occlusion.

Methods: Functional magnetic resonance imaging was collected from 10 healthy volunteers during occlusion of the left first premolar (L1), left second premolar (L2), and right first premolar (R1). The brain activation patterns were analyzed, and the primary sensorimotor cortex, supplementary motor area, insula, thalamus, and prefrontal cortex were chosen as regions of interest.

Results: Single premolar occlusion activated the precentral gyrus, postcentral gyrus, cerebellum, thalamus, frontal lobe, hippocampus, cingulate gyrus, and parietal lobe. The brain areas showing activation during single premolar occlusion were similar to those activated by chewing. The activation pattern of L1 was more similar to that of L2 than R1. No significant left and right hemisphere differences in signal intensity were detected within the regions of interest.

Conclusion: Brain activation patterns from two ipsilateral premolars were more similar than the pattern from a contralateral premolar.     

630名四川农村成人牙本质敏感流行病学调查分析

目的 了解四川省农村成人牙本质敏感的患病状况,并探讨可能的危险因素.方法 采用多阶段、分层、等容量、随机抽样的方法,对四川省农村630名成人进行牙本质敏感问卷调查和口腔临床检查,使用SPSS 18.0软件对调查数据进行统计分析.结果 四川省农村成人牙本质敏感的患病率为27.9%,酸刺激是最常见的敏感诱发因素.第一前磨牙...     

颞下颌关节外科

颞下颌关节 (temporomandibularjoint,TMJ)外科广义讲包括所有需要应用外科手段治疗的TMJ疾病以及关节周围疾病。解剖学、病理形态学、生物化学、免疫学、影像诊断学、生物力学以及医学工程学等方面的进步都为TMJ外科的发展奠定了基础 ,新知识、新理论和新手术方法改变了TMJ外科的面貌和方向。 2 0世纪 70年代以前主要涉及处理TMJ结构 ,解决关节强直 ,80年代以后逐步转向关节镜外科 ,90年代至今关节镜应用的范围在扩大 ,关节重建的方法已更新 ,人工关节的设计、制作和临床使用的报道也在增多。一、TMJ外科的内容1.TMJ损伤 :包括关…     

铸造力对铸钛全冠完整性的影响

本实验的目的是证实铸造力对铸造钛全冠完整性的影响.在树脂牙上进行全冠牙体预备,颊侧边缘为凹型,舌侧边缘为刃状.将18个全冠蜡型分为6组,用专用钛包埋材包埋,用Ohara钛铸造机铸造.1至6组所上的弹簧圈数分别为5、10、15、20、25和30圈,这样便产生逐渐增加的铸造力.第1组只铸出铸道,第2组铸出铸道和部分冠壁;第3、4组的冠大体铸出,但舌侧边缘圆钝并有小的缺损;第5、6组的冠基本完整,边缘锐利,只是舌侧边缘有少数很小的缺损.实验结果表明:①铸造钛金属时要有足够大的铸造力.②如果铸造技术未得到进一步改进,应避免为铸钛修复体设计刃状边缘.     

A comparison of enamelin and amelogenin expression in developing mouse molars

Amelogenin and enamelin are structural proteins in the enamel matrix of developing teeth. The temporal and spatial patterns of enamelin expression in developing mouse molars have not been characterized, while controversy remains with respect to amelogenin expression by odontoblasts and cementoblasts. Here we report the results of in situ hybridization analyses of amelogenin and enamelin expression in mouse molars from postnatal days 1, 2, 3, 7, 9, 14, and 21. Amelogenin and enamelin mRNA in maxillary first molars was first observed in pre-ameloblasts on the cusp slopes at day 2. The onsets of amelogenin and enamelin expression were approximately synchronous with the initial accumulation of predentin matrix. Both proteins were expressed by ameloblasts throughout the secretory, transition, and early maturation stages. Enamelin expression terminated in maturation stage ameloblasts on day 9, while amelogenin expression is still detected in maturation stage ameloblasts on day 14. No amelogenin expression was observed in day 21 mouse molars. Amelogenin and enamelin RNA messages were restricted to ameloblasts. No expression was observed in pulp, bone, or along the developing root. We conclude that amelogenin and enamelin are enamel-specific and do not directly participate in the formation of dentin or cementum in developing mouse molars.