Do miniscrews remain stationary under orthodontic forces?

Miniscrews have been used in recent years for anchorage in orthodontic treatment. However, it is not clear whether the miniscrews are absolutely stationary or move when force is applied. Sixteen adult patients with miniscrews (diameter = 2 mm, length = 17 mm) as the maxillary anchorage were included in this study. Miniscrews were inserted on the maxillary zygomatic buttress as a direct anchorage for en masse anterior retraction. Nickel-titanium closed-coil springs were placed for the retraction 2 weeks after insertion of the miniscrews. Cephalometric radiographs were taken immediately before force application (T1) and 9 months later (T2). The cephalometric tracings at T1 and T2 were superimposed for the overall best fit on the structures of the maxilla, cranial base, and cranial vault to determine any movement of the miniscrews. The miniscrews were also evaluated clinically for their mobility (0: no movement, 1: < or =0.5 mm, 2: 0.5-1.0 mm, 3: >1.0 mm). The mobility of all miniscrews was 0 at T1 and T2. On average, the miniscrews tipped forward significantly, by 0.4 mm at the screw head. The miniscrews were extruded and tipped forward (-1.0 to 1.5 mm) in 7 of the 16 patients. Miniscrews are a stable anchorage but do not remain absolutely stationary throughout orthodontic loading. They might move according to the orthodontic loading in some patients. To prevent miniscrews hitting any vital organs because of displacement, it is recommended that they be placed in a non-tooth-bearing area that has no foramen, major nerves, or blood vessel pathways, or in a tooth-bearing area allowing 2 mm of safety clearance between the miniscrew and dental root.     

Dento-alveolar and maxillofacial injuries – a retrospective study from a level 1 trauma center in Israel

Abstract –  To evaluate the frequency and causes of dental and maxillofacial trauma in hospitalized patients. From January 1, 2000 to December 31, 2003, data from hospitalized trauma patients in a level 1 trauma center in Israel were analyzed according to age, gender, time, place, and cause of injury. Maxillofacial and tooth injuries were separated and further analyzed according to the above parameters. The analysis was based on data from the Israel Trauma Registry (ITR). Of all 14 040 trauma patients, 1038 (7.4%) involved maxillofacial or dental injuries. Common causes of injury were motor vehicle crashes (41%), falls (27%) and intentional injuries (23%). Fifty percent occurred on the street/road, 17% at home and 14% in public buildings. Surgery was required in 55.5% of all maxillofacial injuries. Males were hospitalized three times more than females, and young people, ages 19–28, were at greatest risk (30.2%). Oral and maxillofacial trauma is common, requiring dental health training for primary caregivers.     

A polycaprolactone-β-tricalcium phosphate–heparan sulphate device for cranioplasty

Background

Cranioplasty is a surgical procedure used to treat a bone defect or deformity in the skull. To date, there is little consensus on the standard-of-care for graft materials used in such a procedure. Graft materials must have sufficient mechanical strength to protect the underlying brain as well as the ability to integrate and support new bone growth. Also, the ideal graft material should be individually customized to the contours of the defect to ensure a suitable aesthetic outcome for the patient.

Development of dental Pd-Ti alloys

Alloys, in which the main constituents are palladium and titanium, have the following potential advantages for dental application: corrosion resistance, biocompatibility and acceptable casting temperatures for porcelainfused-to-metal dental prostheses. Alloy compositions chosen for investigation were as follows: 30 w/o Ti which lies in the 5% single-phase region near TiPd, 50 w/o Ti which lies near the 1120°C melting temperature minimum of the Pd?Ti system, and 70% Ti which minimizes Pd content while still in a relatively low melting range (1300°C). Analysis of the X-ray diffraction of 70%Pd30%Ti showed mostly PdTi with some Pd₅Ti₃; in 50%Pd50%Ti mostly PdTi₂ was observed with some PdTi; in 30%Pd70%Ti mostly PdTi₂ was found with some alpha Ti and PdTi₄. The amounts of the minor phases in each of the 3 alloys depended on heat treatment. The Knoop hardness of the alloys ranged from 300–500 KHN for the as-melted condition; after heat treatment the maximum hardness values were 400 KHN. After centrifugal casting, hardness values increased to a range of 350 to 560 KHN, depending on composition. These values exceed those obtained for the pure metals which were in the neighborhood of 100 KHN. From anodic potentiodynamic scans the breakdown potentials in Ringer's solution for 70%Pd30%Ti, 50%Pd50%Ti and 30%Pd70%Ti were 600, 650 and 500 (SCE); the repassivation potentials for the same alloys are 450, 300 and 350 (SCE), respectively. These are all above oral potential. The Pd?Ti system investigated was, thus, found to have adequate corrosion resistance and hardness. Therefore, it can be considered of good potential as a dental prosthetic alloy.     

本科阶段口腔正畸教学模式与质量管理初探

口腔正畸学是口腔医学中专业性极强的分支学科,因而一直是口腔医学难教难学课程。本科生阶段正畸教学时数少,内容多,教学效果难以保证,理论与实践难以结合。医学院校的办学宗旨是培养掌握临床技能的创新人才,上海交通大学口腔医学院口腔正畸教研室为了更好培养适应社会需要,具有国际国内竞争力,适应不同层次要求的口腔医务工作者,坚持教学改革,加强质量管理,经过多年的教学实践,在教学改革和教学管理方面,取得了一些成绩。本文旨在分析正畸教学现状,探讨教学改革和教学质量管理的方法,为进一步深化教学改革、提高教学质量奠定基础。     

小学生唾液隐血试验与口腔健康相关因素调查

目的了解小学生口腔状况及卫生保健行为,分析影响口腔健康的相关因素,探索切实可行的口腔预防保健措施。方法采用口腔检查、唾液隐血试验及问卷调查表对南京市鼓楼区随机抽取的80名五年级小学生进行调查。结果受检小学生唾液隐血阳性率为42.3%,不同性别间的差别无显著性。喜软食组唾液隐血阳性率较阴性组显著增高(P<0.05),阳性组就餐时间较阴性组显著减少(P<0.05),阳性组的错位牙者较阴性组显著增多(P<0.05),在牙齿拥挤度(≥4mm)及前牙深覆盖上(>5mm)均较阴性组有显著增高(P<0.05)。结论要加强对小学生的口腔卫生保健,合理安排其膳食时间及食物搭配,积极矫正错畸形的发生。     

热休克蛋白47重组质粒对糖尿病大鼠皮肤创口愈合影响的实验研究

目的：初步研究热休克蛋白47（HSP47）重组质粒pTraeer—CMV—HSP47局部注射对糖尿病大鼠皮肤创口愈合的影响，探讨以HSP47质粒为摹础的基因治疗促进糖尿病皮肤创口愈合的可行性和有效性．方法：制备四氧嘧啶诱导的糖尿病大鼠皮肤创口愈合模型，创缘皮下局部注射HSP47重组质粒，观察其对皮肤创口愈合的影响，并用免疫组织化学、荧光定量RT—PCR、Western blotting检测创口愈合过程中HSP47和collagen Ⅰ的表达变化。结果：在糖尿病大鼠皮肤刨缘连续两次注射质粒后第3、6、9天．免疫组织化学、荧光定量RT-PCR和Western blotting检测证实，HSP47重组质粒组比对照组能显著增加创口中的HSP47和collagenⅠ的表达。结论：在糖尿病大鼠皮肤创口周围注射质粒pTracer—CMV—HSP47，能明显增强HSP47和coilagenⅠ的表达，有助于改善创口愈合，HSP47可能是促进糖尿病皮肤创口愈合的潜在治疗靶点。     

菌斑固相、变形链球菌及葡聚糖对酸的缓冲作用

目的研究糖代谢后菌斑固相缓冲力的变化及影响因素。方法采集40名18~21岁的大学生的饥饿牙菌斑,体外10%蔗糖孵育1h。体外制备无糖培养和2%蔗糖培养的变链菌团。以25mmol/L KCl制备菌斑固相、变链菌团和不溶性葡聚糖混悬液及可溶性葡聚糖溶液,用1mmol/LHCl滴定并计数细菌密度,统计学分析。结果变链菌团代谢蔗糖后的缓冲容量为(0·099±0·047)mmol/L,比无蔗糖培养的变链菌团的缓冲容量(0·609±0·202)mmol/L低,且缓冲力随细菌密度降低直线下降,葡聚糖几乎没有缓冲作用[(0·028~0·032)mmol/L]。人牙菌斑固相缓冲力的变化规律与体外纯菌培养研究结果一致。结论菌斑固相缓冲力与所含细菌密度密切相关。     

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...