Dental and periodontal complications of lip and tongue piercing: prevalence and influencing factors

Background: The aim of this study was to compare the prevalence of lip and tongue piercing complications and explore the effect of ornament time wear period, habits, ornament morphology and periodontal biotype on the development of complications. Methods: One hundred and ten subjects with 110 lip and 51 tongue piercings were assessed for abnormal toothwear and/or tooth chipping/cracking (dental defects), gingival recession, clinical attachment loss and probing depth of teeth adjacent to the pierced site. Piercing habits (biting, rolling, stroking, sucking) were recorded. Results: Wear time and habits significantly affected the prevalence of dental defects and gingival recession. Pierced site significantly affected dental defects prevalence, with greater prevalence for tongue than lip piercing. Wear time significantly affected attachment loss and probing depth. Attachment loss and probing depth did not significantly differ between tongue and lip piercings. Gingival recession was significantly associated with ornament height closure and stem length of tongue ornaments. Periodontal biotype was not significantly associated with gingival recession, attachment loss and probing depth. Conclusions: Dental defects prevalence is greater for tongue than lip piercing. Gingival recession is similar for tongue and lip piercing. Longer wear time of tongue and lip piercing is associated with greater prevalence of dental defects and gingival recession, as well as greater attachment loss and probing depth of teeth adjacent to pierced sites. Ornament morphology affects gingival recession prevalence.     

南京郊区3～5岁儿童龋病流行情况及相关因素研究

目的调查南京郊区3～5岁儿童龋病的流行情况及相关因素。方法采用多阶段、随机抽样的方法抽取南京郊区384名3～5岁儿童,对其进行口腔检查并发放问卷,由家长填写后统一收回。对龋病相关因素调查结果采用χ2检验和Log-istic回归分析。结果南京郊区3～5岁儿童患龋率为60.68%,龋均及龋面均分别为2.70和4.08;年龄、甜食的喜好程度及母亲文化程度与儿童乳牙龋相关。结论南京郊区3～5岁儿童的患龋率较高,需开展早期预防工作。     

Difficulties with tooth protectors in endotracheal intubation

The suitability of three tooth protectors for routine use during endotracheal intubation was studied in 300 consecutive patients undergoing elective operations under general anaesthesia. The main disadvantages of the protectors were lack of space and the consequent difficulty of guiding the endotracheal tube into the larynx, and poor visibility, especially when the Camo protector was used. These difficulties could be avoided in most cases by cutting off the right angle of the Camo protector. The less experienced anaesthesiologists especially had difficulties with the protectors: 20% of patients in the Camo group were considered impossible to intubate unless the protector was removed. The silicone inlay of the Camo protector melts and becomes adhesive at body temperature, which makes its prolonged use hazardous. Two patients lost a maxillary incisor despite the proper use of a protector (Denex). Thus the use of a tooth protector alone does not guarantee avoidance of dental trauma. Better results could be obtained by improving the design of the protectors and by careful pre-anaesthetic dental examination.     

输送链的结构与齿形探讨(二)——修正齿形链传动及齿形干涉

本文阐述用“包络—轨迹”法修正齿形的齿形链在传动中齿形干涉区的确定,单向传动中增强齿强度的途径,双向传动中避免齿形干涉的设计方法。最后讨论了链节的受力分析,链传动结构容纳节距伸长能力问题。     

Pravastatin restored the infarct size-limiting effect of ischemic preconditioning blunted by hypercholesterolemia in the rabbit model of myocardial infarction

OBJECTIVES

We tested to find out whether pravastatin restores the infarct size (IS)-limiting effect of ischemic preconditioning (IP) and if it has any effect on the IP-induced activation of adenosine producing enzyme ecto-5′-nucleotidase which plays a key role in the IP-induced cardioprotection.

BACKGROUND

The IS-limiting effect of IP is blunted by hypercholesterolemia. Recently, HMG-CoA reductase inhibitors are shown to have direct cytoprotective effects.

METHODS

Rabbits were fed with a normal or cholesterol (1%) added diet with or without pravastatin (5 mg/kg/day) treatment. Infarct size was measured after 30 min occlusion and 3 h reperfusion of circumflex coronary artery with or without the IP procedure (5 min occlusion and 10 min reperfusion). Additionally, ecto-5′-nucleotidase activities of ischemic and nonischemic myocardium were measured immediately after IP procedure.

RESULTS

This dose of pravastatin did not normalize the increased level of serum cholesterol. The IS-limiting effect of preceding IP (IS reduced from 36.7% to 9.6%, p < 0.001) was abolished by hypercholesterolemia (from 46.1% to 31.3%, p = NS) and restored by pravastatin treatment (from 35.2% to 9.4%, p < 0.001). Pravastatin treatment did not affect IS or the effect of IP under normocholesterolemia. The activation of ecto-5′-nucleotidase presented as the activity ratio of ischemic to nonischemic myocardium (3.1-fold in normocholesterolemia) was blunted by hypercholesterolemia (1.8-fold, p < 0.05) and restored by pravastatin treatment (2.9-fold).

CONCLUSIONS

Pravastatin, at the dose serum cholesterol was not normalized, restored the IS-limiting effect of IP and IP-induced ecto-5′-nucleotidase activation, which were both blunted by hypercholesterolemia. The activation of ecto-5′-nucleotidase may be worth further investigation as a possible mechanism for the hypercholesterolemia-induced retardation and pravastatin-mediated restoration of the cardioprotective effect of IP.     

Review: Extracellular Matrix Regulates Tooth Morphogenesis

Mineralized tissues are unique in that they use proteins to attract and organize calcium and phosphate ions into a structured mineral phase, thus precise knowledge of the expression and extracellular distribution of matrix proteins is very important to understand their function. Tooth development is regulated by sequential and reciprocal interactions between neural crest-derived mesenchymal cells and the oral environment. However, the precise molecular mechanisms that mediate interactions between epithelium and mesenchymal cells are not clear, although basement membrane (BM) components have been shown to play important roles in these regulatory events. In addition, the extracellular matrix layer, whose main components are laminin, collagen IV, nidogen, and sulfated proteoglycan, and the BM layer are both considered to be involved with cell proliferation and differentiation. During tooth morphogenesis, extracellular matrices are dramatically changed. Further, the BM components, laminin and collagen IV support dental epithelium; however, in the late stage, they begin the processes of enamel matrix secretion and calcification, after which the BM structure between the dental epithelium and mesenchyme disappears. In addition, tooth abnormalities associated with several kinds of human diseases that cause mutations in the extracellular matrix, as well as the molecular mechanisms of the basement membrane and enamel matrix during tooth morphogenesis, are not clearly understood. In our review, we discuss the role of the extracellular matrix, with focus on the BM and enamel matrix during tooth morphogenesis.     

The Structure of Mineralized Collagen Fibrils

A new model for the structure of mineralized bone collagen is presented which is compatible with neutron diffraction, electronmicroscopic, crosslinking, and composition-density data. Mineralized collagen fibrils are comprised of azimuthally oriented, flexible molecules laterally arranged on a superlattice. Four nearest neighbors are longitudinally staggered by 67 nm and two neighbors by 2* 67 nm. In early stages of mineralization the molecules are parallel to the fibril axis with an average interaxis distance of 1.8 nm. In later stages they become flexed away from the fibril axis by an anisotropic lateral compression of molecules to an interaxis distance of 1.3 nm. Three quarters of the mineral in bone is disposed within the fibrils with a symetry and habit reflecting the above organization of the collagen molecules.     

Applying synthetic radiography to intraoral tomosynthesis: a step towards achieving 3D imaging in the dental clinic

Objectives:A practical approach to three-dimensional (3D) intraoral imaging would have many potential applications in clinical dentistry. Stationary intraoral tomosynthesis (sIOT) is an experimental 3D imaging technology that holds promise. The purpose of this study was to explore synthetic radiography as a tool to improve the clinical utility of the images generated by an sIOT scan.Methods:Extracted tooth specimens containing either caries adjacent to restorations (CAR) or vertical root fractures (VRF) were imaged by sIOT and standard dental radiography devices. Qualitative assessments were used to compare the conspicuity of these pathologies in the standard radiographs and in a set of multi-view synthetic radiographs generated from the information collected by sIOT.Results:The sIOT-based synthetic 2D radiographs contained less artefact than the image slices in the reconstructed 3D stack, which is the conventional approach to displaying information from a tomosynthesis scan. As a single sIOT scan can be used to generate synthetic radiographs from multiple viewing angles, the interproximal space was less likely to be obscured in the synthetic images compared to the standard radiograph. Additionally, the multi-view synthetic radiographs can potentially improve the display of CAR and VRFs as compared to a single standard radiograph.Conclusions:This preliminary experience combining synthetic radiography and sIOT in extracted tooth models is encouraging and supports the ongoing study of this promising approach to 3D intraoral imaging with many potential applications.