塑胶牙套的临床应用

塑胶牙套是近几年来受到关注的新技术。广泛应用于口腔科临床。我科自 2 0 0 0年以来在临床上开展了塑胶牙套的应用。现将应用结果报告如下。1　材料和方法1.1　材料和设备1.1.1　病例选择　为自 2 0 0 0 0 1以来 ,对门诊所有的轻或中度四环素牙欲做漂白的患者、夜磨牙症患者、需做运动防护牙套的患者及固定正畸需做活动保持器的患者 462例 (5 2 8件 )。1.1.2　材料　选用 1.0、2 .0、3 .0mm 3种塑胶薄膜 (美国产 )。贺利氏弹性印模材 ,普通医用石膏。1.1.3　设备　选用F 6G2 4 3 5 3 M型负压吸引器。1.2　方法取摸 ,石膏翻阳模 ,干燥后…     

不同厚度、不同材质护齿膜片能量吸收特性分析

目的 利用冲击试验测试不同厚度、不同材质的护齿膜片吸收能量的性能。方法 1-4、7号膜片分别为BIOPLAST 5、4、3、2、1 mm的软质膜片,5号膜片为ERKOLOC-PRO 2 mm的软硬结合膜片,6号膜片为DURAN 2 mm的硬质膜片。冲击压头从不同高度冲击膜片,利用高速摄像采集系统,拍摄冲击压头下落、压入膜片以及回弹的过程,将图像传输至软件进行数据处理,获得冲击压头的入射速度、入射深度及回弹高度。计算膜片碰撞过程中吸收的能量和吸收能量比,反映不同护齿膜片吸收能量的性能。采用SPSS 22.0软件包中的单因素方差分析及最小显著性差异法,分析不同组别之间的差异。结果 冲击压头下落高度越高,碰撞过程中护齿膜片的能量吸收比越大。软质护齿膜片中,1、2、3、4、7号膜片平均吸收能量比有显著差异（P<0.05）;其中,7号1 mm膜片碰撞过程中平均吸收能量比最大,为（77.98±2.19）%。对于2 mm不同材质的护齿膜片,4、5、6号膜片平均吸收能量比有显著差异（P<0.05）;其中,软质膜片和软硬结合膜片的能量吸收比较大,硬质膜片最小。结论 3 mm护齿膜片的吸收能量性能不亚于4、5 mm膜片,其性能足够支持其用于制作运动护齿,且具有轻薄舒适的优势。软质和软硬结合膜片相比于硬质膜片,更适合用于制作运动护齿。     

Er:YAG激光去除Zenostar T全瓷冠的能量评估方法研究

目的 评估Er:YAG激光作用于不同厚度Zenostar T全瓷修复样品后的温度变化情况,探讨激光能量、材料厚度和温度变化之间的相关性,为临床使用Er:YAG激光去除Zenostar T全瓷冠提供初步的依据与指导.方法 选择Zenostar T全瓷修复材料,制成长和宽均为10 mm,厚度分别为1.0 mm、1.5 mm...     

3种“活动矫治器”基托材料热压处理前后性能比较

目的:比较咬合诱导"活动矫治器"3 种基托材料的弯曲强度、冲击强度、粗糙度、弹性模量和色度,为临床选择材料提供依据.方法:以日进齿科材料有限公司生产的自然义齿基托聚合物Ⅱ型(以下简称日进)、日本株式会社而至生产的而至快速自凝基托树脂(以下简称而至)、上海二医张江生物材料有限公司生产的义齿基托树脂液Ⅱ型和上海医疗器械股份有限公司齿科材料厂生产的义齿基托树脂Ⅱ型(以下简称混合) 3 种基托材料为研究对象,对基托材料进行热压处理;测试挠曲强度、冲击强度、粗糙度及测试色度.测试结果用SPSS 12.0软件进行方差分析和Tamhane T2检验.结果:同一材料的"加压处理组"和"未加压处理组"比较,所有材料冲击强度的改变均有统计学意义,除此以外,个别材料挠曲强度和色度的改变有统计学意义.对于不同材料同一性能的比较,冲击强度:而至＞"混合"＞日进;挠曲强度:日进＞"混合"＞而至;弹性模量:日进＞"混合"＞而至;粗糙度:而至>日进>"混合".结论:热压处理可以作为提高活动矫治器的基托性能的手段;3 种材料比较,各有长短.医师应该结合治疗实际情况选择最合适的材料.     

不同Ⅱ类牵引模式对无托槽隐形矫治磨牙远移作用的比较：三维有限元研究

目的:构建隐形矫治器上颌磨牙远移中两种Ⅱ类牵引的生物力学研究模型,分析矫治体系在不同加力模式、不同牵引力大小作用下的初始位移及应力分布特点,为该技术的临床应用提供参考。方法:建立隐形矫治推上颌磨牙向远中及两种Ⅱ类牵引模式(牙套加力组与牙齿加力组)的三维有限元模型,采用非线性有限元法分析2种不同加力方式及5种不同载荷(100 g、150 g、200 g、250 g、300 g)下的牙齿移动方式、牙套形变、牙周膜应力分布等,比较其增强前牙支抗效果的异同。结果:不同力值不同加力方法下所有组Ⅱ类牵引均可以使前牙内收,抵抗磨牙远中移动过程造成的前牙支抗丧失,但其牙齿应力分布、牙套形变效果不同：牙齿加力组集中在直接受力的尖牙上,分布不均匀;牙套加力组分布更均匀,随距尖牙距离由近到远逐渐减小,但总体大小较牙齿加力组大。牙周膜等效应力除300 g牙套加力组[(2.87×10 -2) MPa]过大外,其余各组均在牙周膜可承受范围内。 结论:100 g的Ⅱ类牵引即可抵抗磨牙远移反作用力造成的前牙支抗丧失,300 g牙套加力作用下的牙周膜受力过大,尽量避免使用。     

不同Ⅱ类牵引模式对无托槽隐形矫治磨牙远移作用的比较：三维有限元研究

目的:构建隐形矫治器上颌磨牙远移中两种Ⅱ类牵引的生物力学研究模型,分析矫治体系在不同加力模式、不同牵引力大小作用下的初始位移及应力分布特点,为该技术的临床应用提供参考。方法:建立隐形矫治推上颌磨牙向远中及两种Ⅱ类牵引模式(牙套加力组与牙齿加力组)的三维有限元模型,采用非线性有限元法分析2种不同加力方式及5种不同载荷(100 g、150 g、200 g、250 g、300 g)下的牙齿移动方式、牙套形变、牙周膜应力分布等,比较其增强前牙支抗效果的异同。结果:不同力值不同加力方法下所有组Ⅱ类牵引均可以使前牙内收,抵抗磨牙远中移动过程造成的前牙支抗丧失,但其牙齿应力分布、牙套形变效果不同：牙齿加力组集中在直接受力的尖牙上,分布不均匀;牙套加力组分布更均匀,随距尖牙距离由近到远逐渐减小,但总体大小较牙齿加力组大。牙周膜等效应力除300 g牙套加力组[(2.87×10 -2) MPa]过大外,其余各组均在牙周膜可承受范围内。 结论:100 g的Ⅱ类牵引即可抵抗磨牙远移反作用力造成的前牙支抗丧失,300 g牙套加力作用下的牙周膜受力过大,尽量避免使用。     

改进自凝义齿基托树脂机械性能的研究

目的 :本研究是在自凝塑料的液剂中加入一定量的高沸点丙烯酸酯 ,用统计方法对改变后的基托材料的力学数据进行分析处理 ,考察它们对固化后的材料力学性能的影响。方法 :在 6 4.0 0mm× 10 .0 0mm× 2 .5 0mm的模具中将四种材料各制备 15个试样 ,抛光后在 37℃的蒸馏水中恒温 2 4h备用。将制备好的试样于WD - 10A万能材料试验机上测试挠度和挠曲强度 ,加荷速度 0 .75mm/min。再在 6 0 .0 0mm× 5 .0 0mm× 4.0 0mm的模具中将四种材料各制备 15个试样 ,在JX - 4型金属冲击强度试验机上测试冲击强度。所有数据进行方差分析 (a =0 .0 5 )。结果 :在自凝牙托水中加入 5 %的二甲基丙烯酸三甘醇酯组 ,其冲击强度下降 ,挠曲强度不变 ,挠度下降 ;加入 5 %的甲基丙烯酸 - 2 -乙基己酯组 ,挠曲强度、冲击强度、挠度均增加 ;加入 2 .5 %的甲基丙烯酸 - 2 -乙基己和二甲基丙烯酸三甘醇酯组 ,其挠曲强度和冲击强度均增加 ,但挠度不变。结论 :在自凝牙托水中加入一定比例的二甲基丙烯酸三甘醇酯和甲基丙烯酸 - 2 -乙基己酯 ,能在一定程度上改善自凝义齿基托的性能     

丙烯酸树脂类暂时修复材料表面厌氧层厚度的测定

目的:体外测量2种丙烯酸树脂基暂时修复材料固化后的表面厌氧层(oxygen-inhibited layer.OIL)厚度,并观察其随时间的变化.方法:利用傅立叶转换红外光谱分析技术,首先建立树脂基体中苯环共轭双键振动峰(1 583 cm-1)吸光度值与树脂薄膜厚度之间的回归直线,然后测定固化后材料表面OIL中苯环共轭双键的吸光度值,代入已建立的直线回归方程中计算出不同时间点的OIL厚度.结果:2种材料树脂薄膜厚度在200 μm以下时,树脂薄膜厚度与苯环共轭双键振动峰吸光度值直线相关.固化后,2种材料的表面OIL厚度在2 min以内下降显著,5 min后OIL厚度没有明显变化(P>0.05).结论:树脂基暂时修复材料固化后会在表面存留一定厚度的OIL,需要进一步研究OIL厚度与树脂修补强度之间的关系.     

垫底厚度对全瓷嵌体修复应力分布影响的三维有限元分析

目的 通过对不同垫底厚度上颌前磨牙全瓷嵌体修复进行三维有限元分析,了解垫底厚度对全瓷嵌体修复应力分布的影响.方法 建立垫底厚度分别为0.5mm,1.0mm和1.5mm的上颌前磨牙邻(牙合)面缺损嵌体修复三维有限元模型,采用3种垫底材料,应用ANSYS10.0有限元分析软件,计算分析应用3种不同厚度垫底时,嵌体和剩余牙体组织的应力分布状况.结果 随着垫底厚度的变化,嵌体、牙釉质和牙本质的最大拉应力,以及粘结剂层的最大剪切力均发生变化.嵌体的最大拉应力、粘结剂层的最大剪切力随着垫底厚度的增加而逐渐增加,当垫底厚度为0.5mm时牙釉质中的最大拉应力最小,而牙本质中的最大拉应力最大.使用不同垫底材料时,随垫底厚度增加,嵌体中的最大拉应力上升的幅度有所不同,玻璃离子垫底组上升的幅度最大,复合体组次之,树脂垫底组上升幅度不明显.结论 弹性模量较低的垫底材料其厚度的变化对嵌体应力改变的影响明显,弹性模量高的垫底材料其厚度的变化对嵌体应力改变的影响不明显.     

无牙下颌不同厚度黏骨膜能量传递率三维有限元分析

目的：分析在冲击载荷下无牙下颌不同厚度黏骨膜能量缓冲能力的大小。方法：利用无牙下颌标准模型建立三维有限元模型,计算不同黏骨膜厚度时能量传递率的大小。结果：随着黏骨膜厚度的增加（0～5．0mm）,黏骨膜能量传递率由100％降至22．55％。结论：黏骨膜的能量缓冲能力随着其厚度的增加而增大。     

EVA mouthguards: how thick should they be?

Abstract – A major consideration in the performance of mouthguards is their ability to absorb energy and reduce transmitted forces when impacted. This is especially important to participants in contact sports such as hockey or football. The thickness of mouthguard materials is directly related to energy absorption and inversely related to transmitted forces when impacted. However, wearer comfort is also an important factor in their use. Thicker mouthguards are not user‐friendly. While thickness of material over incisal edges and cusps of teeth is critical, just how thick should a mouthguard be and especially in these two areas? Transmitted forces through different thicknesses of the most commonly used mouthguard material, ethylene vinyl acetate (EVA) (Shore A Hardness of 80) were compared when impacted with identical forces which were capable of damaging the oro‐facial complex. The constant impact force used in the tests was produced by a pendulum and had an energy of 4.4 joules and a velocity of 3 meters per second. Improvements in energy absorption and reductions in transmitted forces were observed with increasing thickness. However, these improvements lessened when the mouthguard material thickness was greater than 4 mm. The results show that the optimal thickness for EVA mouthguard material with a Shore A Hardness of 80 is around 4 mm. Increased thickness, while improving performance marginally, results in less wearer comfort and acceptance.     

Are all mouthguards the same and safe to use? Part 2. The influence of anterior occlusion against a direct impact on maxillary incisors

Abstract –  The purpose of this study was to clarify the influence anterior occlusion, of mouthguards, has on protecting against a direct collision to the maxillary anterior teeth. In other words, the support mandibular dentition has when wearing a mouthguard. Two types of mouthguards were used for this study, one with an appropriate anterior occlusion or a mouthguard with positive anterior occlusion (MGAO+) and another which was a single-layer mouthguard lacking the same occlusion or a mouthguard with negative anterior occlusion (MGAO−) but with the same thickness on the buccal side. The instruments used for testing were a pendulum-type impact device with two interchangeable impact objects (a steel ball and a baseball), with a plastic jaw model having artificial teeth. Four testing conditions were observed: one with the jaw open without a mouthguard (Open NoMG), the second with the jaw clenching (loaded with 30 kg weight) without a mouthguard (Clench. NoMG), the third with the jaw clenching with MGAO− (Clench. MGAO−) and the last with the jaw clenching with MGAO+ (Clench. MGAO+). The results are as follows: both types of mouthguards showed the effects in reducing the distortion of the teeth. However, the effect was significantly obvious (steel ball = about 57% shock absorption ability, baseball = about 26%) in the mouthguard with anterior occlusion or support by lower dentition through mouthguard (Clench. MGAO+) than Clench. MGAO−. Thus, the influence of anterior occlusion of mouthguards or the support of mandibular dentition through wearing a mouthguard (MGAO+) is indispensable in reducing the impact force and tooth distortion. The results of this research should further contribute to the establishment of guidelines for safer mouthguards.     

防护牙托的性能评价

目的 研究标准型定制类牙托对于外力打击的缓冲能力。方法 利用一个特殊的工作模型。将外力打击时,单个中切牙所受的力通过舌侧金属导杆传递到压力传感器上,记录数据。比较戴防护牙托和无防护时的相对值。结果 获得了不同厚度牙托的缓冲率,各组间差异有显著性。结论 牙托的缓冲效果与材料厚度呈正相关。建议在高对抗性、高风险性的体育活动中,参加者应使用适宜的防护牙托以防止牙外伤的发生。     

Comparison of forces transmitted through different EVA mouthguards

Abstract –  Athletic mouthguards have been recommended for decades with varying levels of athlete acceptance. Issues related to compliance center around the ability to breath and speak while wearing the mouthguards. Fabrication techniques have changed over time to a two-layer ethylene vinyl acetate mouthguard fabricated on a high-pressure machine. The reported ideal thickness of these mouthguards has been somewhat variable depending on the sport and anticipated level of risk. Recent research however, has identified 4 mm as the optimal thickness of EVA. In this study an acrylic dental cast was fabricated and mounted to a drop impact fixture. Mouthguards of varying ply, thickness and palatal coverage were fabricated and tested in the fixture. Strain gauges and load cells were used to evaluate the effect of ply, thickness, and palatal coverage on the ability of these mouthguards to minimize transmitted forces. The purpose of this study was to identify those variables of mouthguard construction that will minimize the overall transmitted force of impact to the anterior dentition.     

The influence of impact object characteristics on impact force and force absorption by mouthguard material

Abstract –  Most impact force and impact energy absorption tests for mouthguards have used a steel ball in a drop-ball or the pendulum device. However, in reality most sports-related trauma is caused by objects other than the steel ball, e.g. various sized balls, hockey puck, or bat or stick. Also, the elasticity, the velocity and the mass of the object could change the degree and the extent of injuries. In this study, we attempted to measure the impact force from actual sports equipment in order to clarify the exact mechanism of dental-related sports injuries and the protective effects of mouthguards. The present study was conducted using the pendulum impact device and load cell. Impact objects were removable. Seven mobile impact objects were selected for testing: a steel ball, baseball, softball, field hockey ball, ice hockey puck, cricket ball, and wooden baseball bat. The mouthguard material used in this study was a 3-mm-thick Drufosoft (Dreve-Dentamid GmbH, Unna, Germany), and test samples were made of the one-layer type. The peak transmitted forces without mouthguard ranged from the smallest (ice hockey stick, 46.9 kgf) to the biggest (steel ball, 481.6 kgf). The peak transmitted forces were smaller when the mouthguard was attached than without it for all impact materials but the effect was significantly influenced by the object type. The steel ball showed the biggest (62.1%) absorption ability while the wooden bat showed the second biggest (38.3%). The other balls or the puck showed from 0.6 to 6.0% absorbency. These results show that it is important to test the effectiveness of mouthguards on specific types of sports equipment. In future, we may select different materials and mouthguard designs suitable for specific sports.     

Forces transmitted through EVA mouthguard materials of different types and thickness

Previous studies into sporting mouthguards have been mainly attitudinal or epidemiological. The aim of the present study was to build an impact rig to measure the impact absorbed by mouthguard materials of various thicknesses. The acceleration of the pendulum of the rig was measured and used to calculate the force transmitted to the materials.
Impact tests were also performed on three commercially available mouthguard materials. Tests showed that the force transmitted through mouthguard materials was inversely related to the material thickness.
Mouthguard construction techniques with ethylene vinyl acetate (EVA) plastics should be monitored to avoid occlusal thinning especially on the incisal edges. Thinning results in reduction in the protection offered by the mouthguard.     

Fabricating a better mouthguard. Part II: The effect of color on adaptation and fit

Abstract –  The thermoforming process involves the heating of plastic sheets to a critical temperature followed by the shaping of the heated material into a three-dimensional structure. Given that custom-fabricated mouthguards are produced using the thermoforming process, the adaptation of plastic sheets to a stone model of the dentition is likely to be affected by the ability of the mouthguard material to be heated. The purpose of this study was to establish if material color affected the adaptation and fit of custom-made mouthguards. Twelve stone models were used in this investigation. Five mouthguards were produced using each model. These mouthguards were made using clear-, white-, black-, blue- and green-colored ethyl vinyl acetate. The force required to remove the various colored mouthguards from the corresponding stone models was determined using a strain gauge housed within a specially designed apparatus. Each of the mouthguards were tested three times at two different angles of pull −45° and 90°. Statistical tests performed using the average amount of force required for mouthguard removal revealed an angle by color interaction. Post hoc analyses revealed that the mean force required to remove the clear-colored mouthguards from their respective stone models was significantly less than the force required to pull away blue-, black- and green-colored mouthguards. This difference between clear- and dark-colored mouthguards was observed at both angles tested with the exception of the black mouthguard which differed from the clear-colored mouthguard only when removed at an angle of 90°. The results of the present study indicate that by using dark-colored mouthguard material, one can achieve superior adaptation and thus produce a more firmly fitting mouthguard.     

The influence of the sensor type on the measured impact absorption of mouthguard material

Abstract –  Mouthguards have been tested for impact energy absorption using drop-ball and/or pendulum devices. While all reports show efficiency of the mouthguard, the impact absorption abilities reported differ considerably. This difference has been attributed to differences of mouthguard material, design, and the impact force used. However, it is also possibly because of the difference in the sensors used in the experiments. The purpose of this study was to test three types of sensors and to assess which type was most appropriate for measurement of the impact absorption ability of mouthguards. A pendulum-type testing equipment and steel ball, wooden bat, baseball, field-hockey ball were used as the impact object. For all sensors or impact objects, the mouthguard decreased the impact forces. However, the absorption ability of the mouthguard varied according to the sensor or impact object. The absorbency values became smaller with the strain gauge, the accelerometer, and the load cell, respectively. With the steel ball as the impact object, 80.3% of impact absorption was measured with the strain gauge and the accelerometer but, only 62.1% with the load cell sensor. With the wooden bat, impact absorption was 76.3% with the strain gauge and 38.8% for the load cell. For the baseball ball, the absorption measurement decreased from 46.3% with the strain gauge to 4.36 with the load cell and for the field-hockey ball, the decrease in measurement values were similar (23.6% with the strain gauge and 2.43% with the load cell). It is clear that the sensor plays an important role in the measurement values reported for absorbency of mouthguard materials and a standard sensor should be used for all experiments.     

Experimental comparative study of various mouthguards

The aim of this study was to evaluate the mechanical and physical properties of several standard size commercially available mouthguards. For the purpose of objective testing, a special study model, which the various gum shield devices could be fitted onto, was developed to record tooth deflection caused by impact forces induced by a pendulum ram impact testing machine. The data measured on teeth provided with various gum shield devices were correlated with those of unprotected teeth; this enabled the individual cushioning effects of the respective devices and their specific force conduction to be evaluated. Using mouthguards considerably diminishes the deflection of the teeth subjected to stress in comparison with the row of unprotected teeth. In addition, force is transmitted to the adjacent teeth all the way to the distal regions of the row of teeth. The individual cushioning effects are directly correlated to the thickness of the material; the force distribution is determined by the rigidity of the gum shield device. The devices examined showed considerable differences with regard to force distribution and dimensioning. The study showed that this was due to the thickness of the materials, the manufacturing process and the composition of the materials of the devices examined. In comparison to laboratory-produced devices of similar material thickness, the devices that were designed to be fitted by the user achieved significantly poorer results as regards both cushioning properties and dissipation of exerted forces.