面磨耗对下颌第一磨牙牙体长轴倾斜程度影响的解剖测量研究

目的 :探索牙合面磨耗对下颌第一磨牙牙体长轴倾斜程度的影响和意义。方法 :从本教研室收藏的 34 18个下颌第一磨牙中 ,按下列标准选出 3组牙齿进行微机测量。Ⅰ组 :无磨耗组 ,18个 ,代表年轻组 ;Ⅱ组 :严重磨耗组 ,2 6个 ,代表年长组 ;Ⅲ组 :牙合面深龋组 ,18个 ,代表功能减弱组。样本中所有牙均选双根者 ,由三位作者遵三盲法进行。结果 :Ⅱ组牙冠相对于牙根更向近中倾斜 ,与Ⅰ组有明显差异 (P <0 .0 1) ,而Ⅲ组与Ⅰ组无明显差别。结论 :重度磨耗的下颌第一磨牙 ,牙体长轴的倾斜程度明显大于无明显磨耗组 ,其机制可能与咬合功能刺激有关。     

下颌第一磨牙(牙合)面磨耗近中根受力影响的三维有限元分析

目的:采用三维有限元技术,分析下颌第一磨牙在(牙合)面水平磨耗与倾斜磨耗2种情况下受力时,其牙体内的应力分布和瞬间位移情况,探讨近中根纵裂发生的生物力学依据.方法:运用Mimics有限元软件建立下颌第一恒磨牙三维有限元模型,分为无磨耗组(对照组)、水平磨耗组(实验组1)和倾斜磨耗组(实验组2)3组,实验组1和实验组2再根据4种磨耗程度,分别建立平切1、平切2、平切3、平切4和斜切5°、斜切10°、斜切15°与斜切20°8种研究模型.经(牙合)面加载200 N的咬合力,运用MSC.Marc非线性有限元分析软件分析各种状态下模型内的等效应力和瞬间位移,分析牙根纵折发生的生物力学依据.结果:①无磨耗组第一磨牙应力主要集中在(牙合)面中央窝沟处,位移等值线主要集中在牙冠近中偏颊(牙合)面,向下延伸至牙颈部.②水平磨耗组应力主要集中于牙冠部及近远中根的根分叉水平,位移等值线整体逐渐偏向(牙合)面近中偏颊侧牙颈部区域,类似于楔状缺损的V型.③在倾斜磨耗组,当磨耗平面向远中倾斜角度由5°增至15°时,瞬间位移等值线与牙长轴交角变小,近中根所受剪切力最大,产生的应力集中,发生牙根纵裂的可能性增大;当倾斜角度增大至20°时,应力主要集中在牙冠部,其位移等值线呈环形,最大位移出现在牙冠内.提示临床上当牙冠磨耗严重、牙尖斜面明显倾斜时,倾斜牙尖成为应力集中区,易发生折裂.结论:下颌第一磨牙(牙合)面磨耗面向远中倾斜时,其近中根发生纵裂的可能性较大,为临床上预防性调磨过度磨耗的下颌第一磨牙,降低近中根纵裂的可能性提供了生物力学依据.     

第一磨牙的生理性磨耗

目的：通过对上、下颌第一磨牙不同部位生理性磨耗的观察，探讨磨耗特征及其生理意义。方法：５５１ 个上颌第一磨牙和６８６ 个下颌第一磨牙，根据磨耗程度分为轻、中、重度（ 绝对磨耗程度），根据单个牙上不同部位磨耗程度排序（ 相对磨耗程度），比较各部差别。结果： 上颌第一磨牙磨耗程度由重到轻排序：近、远舌尖＞ 近、远中边缘嵴＞ 近、远颊尖；下颌第一磨牙排序：远中尖、远中边缘嵴＞ 近、远颊尖＞ 远舌尖＞ 近舌尖、近中边缘嵴。结论：上颌第一磨牙以舌尖磨耗最重，而下颌第一磨牙则为远中部磨耗最重，可能与局部咬合力作用时间及作用强度有关。     

正畸治疗中磨牙的拔除和保留(二十一)——应用全颌曲面断层片对下颌磨牙冠根形态的比较研究

目的：统计分析下颌第一、第二、第三磨牙牙冠近远中宽度、牙体长度、分根情况以及相关因素。方法：选择下颌无缺失牙,下颌第三磨牙牙根发育已完成的全颌曲面断层X线片249张进行测量分析。结果：牙体长度下颌第一磨牙至第三磨牙依次递减;牙冠近远中宽度下颌第一磨牙最大,第二、第三磨牙无差别;分根率下颌第一磨牙至第三磨牙依次递减,根分叉程度下颌第一磨牙最大,第二、第三磨牙无差别;下颌第三磨牙萌出组牙体长度大于第三磨牙阻生组,并且与其牙冠近远中宽度成正相关,分根率也偏大;下颌第三磨牙相对宽度在单根、双根组间有差别;下颌第三磨牙牙冠宽度/磨牙后间隙长度比值与下颌第三磨牙相对长度比成负相关关系。结论：下颌第一磨牙冠根形态最好;第二、第三磨牙冠根形态有较大的相似性,只要有足够的空间,下颌第三磨牙牙根就能得到良好的发育。     

自然牙牙裂综合征患者牙磨耗的自身对照研究

目的:调查自然牙裂综合征病例中患牙磨耗模式,评价牙磨耗在自然牙裂综合征(cracked tooth syndrome,CTS)组和自身对照(OC)组间有无差别。方法:49例CTS组患牙,以对侧同名牙为对照组,取研究模观察。结果:(1)磨耗指数:CTS组得1分者8个(16.33%),得2、3分者33个(67.35%),得4分者8个(16.33%);对照组得1分者14个(28.57%),得2、3分者29个(59.18%),得4分者6个(12.24%)。2组相比差异无显著性(P>0.05);(2)相对磨耗:上颌前磨牙舌尖和下颌第一磨牙近颊尖CTS组与对照组具有统计学差异(P<0.05);(3)牙折方向:上颌前磨牙和上颌第二磨牙以近远中向裂为主,依次占各自折裂牙样本的91.67%和88.89%,而上、下颌第一磨牙及下颌第二磨牙的牙折裂方向没有表现出明显趋向性。结论:上颌前磨牙舌尖及下颌第一磨牙近颊尖磨耗相对不足与牙折裂密切相关。     

拔除下颌磨牙矫治安氏Ⅲ类错（牙合）关系的临床分析

目的：评价下颌第一磨牙拔除进行正畸治疗安氏Ⅲ类错（牙合）关系的疗效,第二磨牙向前移动代替第一磨牙的适应症,支抗控制方法等。方法：选择正畸门诊16例Ⅲ类错（牙合）关系并伴有下颌第一恒磨牙残冠、残根或牙冠大面积充填,在患者知情同意下拔除第一恒磨牙,使用直丝弓技术进行矫治。结果：所有16例病例均拔牙间隙完全关闭,无近中倾斜及舌倾现象。双侧磨牙Ⅰ类关系,面角减少,患者侧貌较直,取得较为满意的矫治疗效。结论：拔除下颌磨牙结合矫正技术可成功矫治恒牙期轻度骨性Ⅲ类错（牙合）畸形,并使患者软组织侧貌发生明显改变。     

利用种植体支抗远移下颌磨牙的效果评价

目的：研究安氏Ⅲ类错患者中,采用微型种植体作支抗,远移下颌磨牙的临床效果及其作用特点。方法：选择16例成人患者,将32枚微型种植体植于下颌第二前磨牙与第一磨牙之间颊侧牙槽骨内,Ni-Ti螺旋弹簧压缩后置于下颌第一前磨牙与下颌第一磨牙之间,推磨牙远移。通过测量下颌第一磨牙在近远中方向、垂直向的位置变化,以衡量磨牙的位置改变。并通过下颌中切牙的位置变化,评价支抗强弱。结果：下颌第一磨牙平均远中移动4.5mm,疗程5.4个月,平均移动速度0.8mm/月;磨牙长轴向远中倾斜角度为3.9°。下颌中切牙位置基本无改变。结论：所有下颌磨牙被远移到了恰当的位置。未见前牙支抗丧失。种植体作支抗推下颌磨牙远移的过程中,发挥了强支抗的作用。临床操作较方便,是一种值得推广的方法。     

利用Tip-Edge第一期矫治技术非拔牙矫治安氏Ⅱ类1分类错[牙合]的临床研究

目的：应用Tip-Edge I期矫治技术对治疗非拔牙安氏Ⅱ类1分类错[牙合]进行矫治,并对矫治机理进行探讨。方法：临床筛选病例12例。矫治前后拍摄头颅侧位定位片,并对相关指标进行模型测量。治疗前后相关头影测量项目测量值输入计算机,用SAS软件包对各测量值进行配对t检验。结果：Tip-Edge I期矫治结束后,上颌切牙倾斜（U1-SN,U1-Apog）明显减小,而下颌切牙的倾斜明显增加（P〈0.01）覆牙合超[牙合]显著减小。上颌第一磨牙远中移动1.5 mm,远中直立3.5°,有显著性差别。模型测量分析表明上颌尖牙间宽度和磨牙宽度显著增加。下颌尖牙间的宽度无显著变化。下颌磨牙宽度显著增加。结论：利用Tip-Edge I期技术能够非拔牙矫治处于生长发育期的安氏Ⅱ类1分类错[牙合]。对处于生长发育期具有良好生长型（水平生长型）和生长潜力的患者较易取得良好的效果。     

利用倾斜下颌第三磨牙作固定桥

目的 利用倾斜第三磨牙制作固定桥,修复下颌磨牙缺失。方法 选择下颌第二磨牙或第一、第二磨牙都缺失且第三磨牙已有不同程度倾斜的病例１１例,通过纠正第三磨牙长轴后,以其作为固位体修复缺失牙。结果 随访１－３年,所的缺牙修复咀嚼功能良好,基牙无牙体牙周病变。结论 本方法扩大了固定桥的应用范围,同时保存了第三磨牙,并有效地恢复其咀嚼功能。     

骨性Ⅲ类与Ⅰ类错患者基骨及牙弓宽度的比较研究

目的：评价骨性Ⅲ类错合与骨性I类个别正常合上下颌第一磨牙区基骨及牙弓宽度差异。方法：选取骨性Ⅲ类错合患者与骨性I类个别正常合样本各30例。测量CBCT数据中上颌骨颧弓点和下颌第一磨牙阻抗中心对应的颊侧骨皮质点间的距离作为基骨宽度；测量模型上下颌第一磨牙中央窝之间的距离作为牙弓宽度。使用SPSS 22.0独立样本t检验。结果：上颌基骨宽度Ⅲ类组（63.96±3.78mm）小于I类组（65.67±2.76mm）；下颌基骨宽度Ⅲ类组（62.26±3.12mm）大于I类组（60.29±3.15mm）；基骨宽度差为Ⅲ类组（2.31±2.41mm）小于I类组（5.38±1.24mm）。差异均有统计学意义（P<0.05）。Ⅲ类组与I类组上下颌牙弓宽度均无组间差异（P>0.05）。结论：骨性Ⅲ类患者存在上下颌基骨横向发育不调及上下颌磨牙的颊舌向代偿。     

Study of orientation of enamel prisms in cervical tooth area

The orientation of enamel prisms in mesio-distal plane was investigated in cervical tooth area in relation to the long axis. The X-ray diffraction method from successive planes of apatite-crystal lattice, nas used. Testings were done on mesial and distal tooth surfaces in four groups of human lateral teeth: maxillar premolars and molars and mandibular premolars and molars. According to the obtained results the apical orientation was the most frequent orientation in all investigated teeth (54-84%). Horizontal orientation of enamel prisms was found in 2-18% of cases and occlusal in 4-32% of teeth.     

Dental attrition and degenerative arthritis of the temporomandibular joint

The extent and rate of occlusal attrition in relation to degenerative arthritis of the temporomandibular joint were studied in 101 skulls representing early Aboriginal man in Australia. Joint degenerations affected 40% of the specimens and were associated with both the rate and extent of tooth attrition. Age, unaccompanied by tooth wear, was not significant in the progress of the disease. Degenerations affected the temporal joint surface more frequently than the condyle, particularly in the lateral and central regions of the articular eminence. Patterns of degenerative joint disease in the Aboriginals illustrated a break-down in the physiological adaptability of the masticatory system resulting from increased occlusal stress consequent upon progressive tooth wear. Under these conditions, the teeth and the temporomandibular joints enter a ‘wear-out’ phase of occlusal function which usually commences in early adult life and becomes more severe as the conditions continue.     

Relationship between occlusal wear of the teeth and periodontal health

abstract – The study was undertaken in order to examine the relationship between occlusal wear and periodontal health in thc maxillary and mandibular anterior, premolar and molar regions of the human dentition. The occurrence and degree of attrition was recorded for the 4,316 fully erupted teeth of 154 males aged 19–22 years. The mandibular central incisors and the canines of both jaws were found most often to show attrition. In general, occlusal wear was found to be associated with improved cleanliness, and thus, in most areas of the dentition, also with improved periodontal conditions. At the openings of the major salivary glands, however, more calculus was found on attrited than intact teeth, and consequently, no improvement of the periodontal status was found in mandibular anterior teeth and maxillary molars. As the degree of attrition was not influenced by the frequency of toothbrushing, it seems evident that the masticatory function which results in occlusal wear of the teeth, has an effect per se on periodontal health.     

Tooth wear among psychiatric patients: prevalence, distribution, and associated factors

PURPOSE: The purpose of this study was to evaluate the prevalence, distribution, and associated factors of tooth wear among psychiatric patients. MATERIALS AND METHODS: Tooth wear was evaluated using the tooth wear index with scores ranging from 0 to 4. The presence of predisposing factors was recorded in 143 psychiatric patients attending the outpatient clinic at the Prince Rashed Hospital in northern Jordan. RESULTS: The prevalence of a tooth wear score of 3 in at least one tooth was 90.9%. Patients in the age group 16 to 25 had the lowest prevalence (78.6%) of tooth wear. Increasing age was found to be a significant risk factor for the prevalence of tooth wear (P < .005). The occlusal/incisal surfaces were the most affected by wear, with mandibular teeth being more affected than maxillary teeth, followed by the palatal surface of the maxillary anterior teeth and then the buccal/labial surface of the mandibular teeth. The factors found to be associated with tooth wear were age, retirement and unemployment, masseter muscle pain, depression, and anxiety. CONCLUSION: Patients' psychiatric condition and prescribed medication may be considered factors that influence tooth wear.     

A functional aspect of anterior attrition or flaring and mode of treatment.

The phenomenon of occlusal wear has been generally reported, with no distinction being made between wear of the anterior or posterior teeth. This paper describes a group of patients without oral habits and exhibiting anterior tooth attrition or flaring with minimal posterior tooth attrition. The mandibular anterior movement patterns of the patients studied were evaluated using a Sirognathograph. These patterns appear to be the etiology for the anterior attrition or flaring present. A treatment mode allowing coexistence of this phenomenon with an anterior guidance that does not interfere with the mastication pattern is proposed. A hypothesis that might explain the clinical findings and a mode of treatment are described.     

半坡博物馆馆藏六千年前人颌骨牙齿的磨耗状况分析

目的:调查六千年前新石器时期古人牙齿的磨耗状况,以探寻牙齿磨耗的规律及其演化发展趋势。方法:观察记录并统计了西安半坡博物馆馆藏76例人头颅骨全部牙齿的磨耗情况,用SPSS 12.0软件对全部的904个牙齿进行了统计学分析。结果:不同磨耗度牙齿的构成比中,2°磨耗的比例最高(37.06%)。左右上下对称牙位牙齿的磨耗基本相同。第一磨牙的磨耗程度最重,第三磨牙的磨耗程度最轻。不同年龄段牙齿磨耗度有显著性差异,随年龄的增长,牙齿磨耗度逐渐加重。每一牙位牙齿平均磨耗度男女性别间无显著性差异(P>0.05)。结论:新石器时代古人牙齿的总体磨耗程度较现代人重。     

正常及重度磨耗牙合下颌牙根尖应力分布规律的光弹实验研究

目的 :探明正常牙合与重度磨耗牙合两种不同牙合型时各牙根尖应力分布的特征 ,以期揭示牙的解剖形态及牙尖高度的改变对咬合力传导的影响规律。方法 :采用透明环氧树脂复制相同牙排列而成的正常牙合及重度磨耗牙合的下颌模型 ,2 .0kg垂直加载后 ,在国产 40 9-II型投影式光弹仪上观察测量各牙根尖主应力的大小与方向。结果 :近远中方向上 ,重度磨耗牙合下颌牙列中各牙均受到冠向远中、根向近中的转矩力作用。颊舌方向上 ,两种咬合的牙根尖主应力方向相差不显著。重度磨耗牙合各牙根尖应力水平普遍高于正常牙合的相应各牙。结论 :牙齿咬合面正常解剖形态及牙冠高度的丧失对由牙齿向下颌骨传导的生物力有显著影响     

Dental cervical lesions associated with occlusal erosion and attrition

Acid demineralization of teeth causes occlusal erosion and attrition, and shallow and wedge-shaped cervical lesions putatively involving abfraction. From 250 patients with tooth wear, 122 with cervical lesions were identified. From epoxy resin replicas of their dentitions, associations of occlusal attrition or erosion or no wear with cervical lesions were recorded at 24 tooth sites (total 2928 sites). Criteria used to discriminate occlusal attrition from erosion, and shallow from grooved, wedge-shaped or restored cervical lesions were delineated by scanning electron microscopy. A 96 per cent association was found between occlusal and cervical pathology. Shallow cervical lesions were more commonly found in association with occlusal erosion. Wedge-shaped lesions were found equally commonly in association with occlusal erosion, as with attrition. Grooved and restored cervical lesions were uncommon. Differences were appreciated in the associations within incisor, canine, premolar and molar tooth sites which related more to the site-specificity of dental erosion than to attrition from occlusal forces. Non-carious lesions on teeth then have multifactorial aetiology and pathogenesis in which erosion and salivary protection play central roles. Dentists should primarily consider erosion in the diagnosis, prevention and treatment of tooth wear.     

传统全景片和锥形束CT重建全景片测量牙轴近远中倾斜度的对比研究

目的 比较传统全景片和锥形束CT（CBCT）重建全景片用于测量牙轴近远中倾斜度的准确性。方法 收集15名个别正常志愿者的石膏模型,在模型上确定上下颌从左侧第一磨牙到右侧第一磨牙的牙体长轴和平面的标记点,制作放射显影装置,志愿者佩戴放射显影装置拍摄全景片和 CBCT片。分别在石膏模型、全景片和 CBCT重建全景片上测量牙轴近远中倾斜度。利用多元方差分析和 Dunnett-t检验比较3种测量方法的差异。结果 3种测量方法间的差异有统计学意义（P=0.00）。与模型测量相比,全景片组中12个牙位有2个牙位（上下颌第二前磨牙）测量结果的差异有统计学意义（P=0.00）,CBCT组12个牙位的差异均无统计学意义。结论 评价牙轴近远中倾斜度时,传统全景片存在一定误差, CBCT重建全景片是一种更为有效的评价手段。     

The role of erosion in tooth wear: aetiology,prevention and management

Tooth wear is a universal experience. The cause is usually a combination of erosion, attrition and abrasion. Attrition usually presents with flattened incisal and occlusal tooth surfaces which accurately inter‐digitate. Erosion from dietary or gastric acids forms smooth lesions which typically appear as cupped occlusal/ incisal and concave buccal/facial surfaces. When combined with attrition or abrasion, acids have the potential to cause significant wear. Wear reduces the thickness of enamel exposing the underlying dentine and changing the colour from the white of enamel to yellow of dentine. Acids causing erosion originate from the stomach or from the diet. Gastric acid is associated with reflux disease and eating disorders. The frequency of acidic foods and drinks and how they are consumed is important in dietary erosion. The progression of tooth wear is recognised to be slow with periods of activity and inactivity. Although restorations can be indicated, prevention and monitoring remain important strategies in maintaining the life of the teeth.