运用激光扫描和三维重建技术测量蒙古族和汉族青少年上切牙的厚度及宽度

目的 测量并分析呼和浩特地区蒙古族和汉族人群上切牙牙冠厚度、宽度及宽厚比例的相关性。方法 筛选120副蒙古族和汉族青少年牙模型,对样本模型激光扫描并三维重建,测量上切牙厚度及宽度,采用配对t检验及回归分析。比较不同民族及性别宽度与厚度的差异,并分析宽厚比例及相关关系。结果 ①上切牙厚度男性>女性(P<0.05）。②上颌侧切牙厚度蒙古族>汉族(P<0.05）。③蒙古族上颌中切牙及侧切牙宽度男性>女性(P<0.05）;汉族上颌中切牙宽度男性>女性(P<0.05）。④上颌侧切牙牙冠宽度蒙古族>汉族(P<0.05）。⑤蒙古族和汉族上切牙牙冠厚度与宽度均具有线性关系。结论 上颌切牙的边缘嵴厚度及宽度存在性别及民族差异,牙冠厚度与宽度呈线性相关关系,同时建立了本地区蒙古族和汉族人群牙冠宽度及厚度的均数及标准差,为本地区患者临床正畸治疗中前牙美学及覆覆盖的设计提供理论参考。     

上颌切牙的牙颈部形态测量及分析

目的 :本研究通过测量获得天然上颌切牙牙颈部宽度、厚度及牙颈曲度等数据,为切削制作个性化愈合基台提供依据。方法:采用电子游标卡尺对173颗离体上颌切牙(中切牙104颗、侧切牙69颗)的颈部近远中宽度、颊舌向厚度,近中牙颈部曲度、远中牙颈部曲度,釉牙骨质界(CEJ)根方1.5 mm颈部宽度、颈部厚度进行测量。每部位测量3次,数据以均数±标准差(x±s)表示,精确到0.01 mm。结果 :上颌中切牙及上颌侧切牙在颈部宽度、颈部厚度、CEJ根方1.5 mm颈部宽度与颈部厚度、近中颈曲度与远中颈曲度方面的差异均具有统计学意义(P<0.05)。上颌中切牙CEJ及CEJ根方1.5 mm颈部宽度大于颈部厚度;上颌侧切牙CEJ及CEJ根方1.5 mm颈部厚度大于颈部宽度。结论:上颌切牙基台顶端应设计为弧形,上颌中切牙、侧切牙基台近中颈部曲度应大于远中颈部曲度,近远中应为外形最高点,唇舌侧应为外形最低点。     

Micro-CT测量三千年前人上颌第二前磨牙釉质厚度的研究

目的:用Micro-CT扫描重建陕西地区出土三千年前人上颌第二前磨牙,测量并记录其牙冠釉质厚度,比较不同部位釉质厚度的差异,以期摸索一种新的古代牙齿标本形态数据的保存方式,并为研究中国人牙齿的演化过程积累资料。方法:用Micro-CT扫描20个陕西地区出土三千年前人的上颌第二前磨牙,三维重建,准确定位后测量牙冠不同部位的釉质厚度。结果:三千年前人上颌第二前磨牙舌尖处釉质厚度大于颊尖处的釉质厚度(P<0.05);远中釉质厚度大于近中釉质厚度(P<0.05);舌面釉质厚度大于颊面(P<0.05);舌侧咬合区釉质厚度大于颊侧咬合区厚度(P<0.05)。结论:三千年前人上颌第二前磨牙釉质厚度在牙冠不同部位分布存在差异。     

离体上颌第一、二磨牙在釉牙骨质界截面的牙体硬组织厚度测量

目的观察上颌第一、二磨牙在釉牙骨质界(cemento-enamel junction,CEJ)的截面几个方向的牙体厚度。方法25个离体的上颌第一磨牙,22个上颌第二磨牙。从CEJ横断牙冠,将截面图象输入计算机中,用photoshop6.0软件测量牙面到髓腔的距离,方向分别是颊、腭、近中、远中、近中颊、远中颊、近中腭、远中腭。结果在CEJ平面厚度最小处是上颌第二磨牙的近中(平均2.55mm),最厚处是上颌第一磨牙近中舌(平均3.34mm),总体看以近中颊、远中颊、进中舌、远中舌部位相对较厚。结论本研究强调了在釉牙骨质界平面测量牙体厚度对于牙体预备的价值。     

上颌尖牙埋伏阻生患者上颌切牙牙齿宽度改变的研究

目的探讨中国人上颌切牙宽度与尖牙阻生是否存在内在的联系.方法选择103名上颌尖牙埋伏阻生患者,分为46名腭侧阻生组和57名唇侧阻生组.选择年龄、性别匹配,上颌尖牙正常萌出的患者60名,作为对照组.测量这些患者的上颌切牙近远中宽度,并进行统计学分析.结果尖牙阻生患者的左右侧中切牙及侧切牙的近远中宽度基本一致,无统计学差异.尖牙唇侧阻生患者的侧切牙宽度大于对照组,腭侧阻生患者的侧切牙宽度小于对照组,均有统计学差异.唇腭侧阻生患者的侧切牙宽度有显著性差异.结论尖牙埋伏阻生患者的上颌切牙宽度变化和尖牙阻生的位置有着高度的相关性.     

改良式摆型矫治器远中移动上颌磨牙的疗效分析

目的 评价改良式摆型矫治器远中移动上颌磨牙的疗效。方法 选择14例牙性安氏Ⅱ类错的患者,应用改良式摆型矫治器远移上颌第一磨牙,通过矫治前和磨牙远移到位后的X线头影测量分析评价其疗效。结果 磨牙平均向远中移动3.85mm,牙冠远中倾斜3.22°;切牙近中倾斜移动2.08mm,覆盖增加1.68mm。结论 改良式摆型矫治器能有效地整体远中移动上颌磨牙,快速矫正磨牙关系,但也会引起少量的支抗丧失和切牙唇向移动。     

Distal-Jet 矫治器远中移动上颌磨牙的疗效

目的:评价Distal-Jet矫治器远中移动上颌磨牙的疗效。方法:应用Distal-Jet矫治器对12例平均年龄为12.3岁,由于上颌磨牙前移所致的安氏Ⅱ类错患者进行治疗,通过远中移动磨牙前后的头影测量分析和模型测量分析评价其远中移动磨牙的疗效。结果:①磨牙平均向远中移动(3.6±0.75)mm,牙冠远中倾斜(3.5±3)°;②第一前磨牙近中移动(2.1±1.7)mm,牙冠近中倾斜(3.1±2.57)°,前牙覆盖增加(1.47±1.76)mm;③磨牙和第一前磨牙分别伸长(0.39±0.46)mm和(0.43±0.61)mm;④双侧上颌第一磨牙中央窝间宽度增加(2.8±1.1)mm。结论:Distal-Jet矫治器能有效地整体远中移动上颌磨牙,但也会引起少量前磨牙的近中移动及牙冠近中倾斜。     

下颌切牙唇舌径宽度与单双根管之间关系的CBCT研究

目的:采用CBCT观察下颌恒切牙根管形态,分析下颌切牙唇舌径宽度及近远中宽度与单双根管之间的关系。方法:选取75名进行CBCT扫描的患者,共计282颗下颌切牙,测量其釉质牙骨质界处唇舌径及近远中径宽度,并观察其根管形态。结果:下颌切牙单双根管的唇舌径宽度平均宽度分别为5.62mm、6.35mm,具有显著性差异(P<0.001),与性别差异无关,唇舌径的宽度的最佳界值为6.05 mm。单双根管的近远中径宽度平均宽度分别为4.00mm、4.04mm,无显著性差异(P=0.423)。结论:当唇舌径宽度大于或等于6.05mm时,可以提示下颌切牙双根管的存在的可能,唇舌径宽度的大小能够作为一种下颌切牙根管治疗术前的评估指标。     

一九八一年日本第七十次口腔科医师国家考试题(续)

<正> 正确者下面画“﹏”正畸学20题21.测量一尖牙唇向低位错位的模型,结果牙冠近远中宽度、牙弓宽度、牙槽基底宽度均正常,但牙弓长径、牙槽基底长径小,试推测发生原因。(1)乳切牙滞留,恒切牙舌向错位;(2)乳磨牙滞留,双尖牙舌向错位;(3)乳切牙早失,恒切牙远中错位;(4)乳磨牙早失,恒磨牙近中错位。     

安氏Ⅰ类拥挤拔牙矫治后磨牙及切牙位置变化的研究

目的 :探讨安氏I类错牙合牙列拥挤经拔除 4个第一前磨牙矫治后磨牙及切牙位置的变化。方法 :选用泸州医学院附属口腔医学院正畸科连续收治的安氏I类错牙合牙列拥挤患者 2 0例 (男 8,女 12 ) ,年龄 14～16岁。均采用拔除 4个第一前磨牙 ,用方丝弓细丝弓技术矫治 ,牙性支抗。在矫治前后摄X线头颅定位侧位片 ,对磨牙及切牙位置进行测量比较分析。结果 :上颌磨牙牙冠平均前移 3 .15mm ,上颌切牙牙冠平均后移 2 .5 5mm ;下颌磨牙牙冠平均前移 4.3mm ,下颌切牙牙冠平均后移 1.78mm。结论 :牙性支抗 (弱支抗 )控制下 ,安氏Ⅰ类错牙合牙列拥挤拔牙矫治后上下磨牙及切牙位置均有明显变化 ,且相对RL线磨牙前移较切牙后移更大。     

四川地区人离体上颌恒中切牙及其唇面发育沟的形态学观测

目的观察四川地区人上颌恒中切牙发育沟的表面结构特征,以指导固定修复体的仿真制作。方法采用一定纳入标准选择58颗四川地区人离体上颌恒中切牙,测量其解剖牙冠长度、宽度,近远中发育沟长度、宽度,以及近远中发育沟两边界之夹角。结果四川地区人上颌恒中切牙的解剖牙冠冠长和冠宽分别为（11.9±1.3）mm和（8.7±0.8）mm,发育沟长和沟宽分别为（5.7±0.9）mm和（2.1±0.5）mm,近远中发育沟长度和宽度的差异均无统计学意义。冠长与发育沟长的比值为2.1,冠宽与发育沟宽的比值为4.2。近中发育沟两边界之夹角为23°±4.7°,远中发育沟两边界之夹角为23°±5.7°。结论四川地区人上颌恒中切牙解剖牙冠的长、宽平均值与中国人的平均值接近;冠长与发育沟长之比、冠宽与发育沟宽之比恒定,发育沟所成角度的大小较确定;其数值为固定修复体的仿真制作提供了参考。     

Relationship between the width of the zone of keratinized tissue and thickness of gingival tissue in the anterior maxilla

The aim of this study was to evaluate whether there is a positive correlation between the width of the zone of gingival keratinized tissue and its thickness. Maxillary right canines, lateral incisors, and central incisors of 60 patients (30 men, 30 women) between the ages of 20 and 35 years were examined. Using an endodontic spacer with a rubber cursor and a digital caliper of 0.01-mm resolution, the values of the width of the zone of gingival keratinized tissue and gingival thickness were obtained. It was observed that the lateral incisor has the largest mean zone of gingival keratinized tissue (5.54 ± 1.09 mm), followed by the central incisor (4.62 ± 1.02 mm) and canine (4.32 ± 1.33 mm). The mean gingival thickness was greater in the central incisor (1.17 ± 0.20 mm), followed by the lateral incisor (1.04 ± 0.24 mm) and canine (0.87 ± 0.27 mm). No statistically significant difference was verified for the mean width of the zone of gingival keratinized tissue and gingival thickness between men and women. A positive correlation between gingival thickness and width of the zone of gingival keratinized tissue was observed in the maxillary canine (Pearson r = 0.398, P < .05), lateral incisor (Pearson r = 0.369, P < .05), and central incisor (Pearson r = 0.492, P < .05). In patients 20 to 35 years of age, there was a positive correlation between gingival thickness and width of the zone of gingival keratinized tissue for the maxillary right canine, lateral incisor, and central incisor.     

191例福建居民上颌前牙解剖长度及宽度分析

目的: 通过锥形束CT（cone-beam CT, CBCT）测量分析,了解福建居民上前牙解剖学特征,为进行上颌前牙区修复提供参考。方法: 利用CBCT测量191例就诊于福建医科大学附属口腔医院门诊患者的1 146颗上前牙（中切牙、侧切牙、尖牙）各牙位的长度及宽度,根据性别进行分组,量化分析牙体解剖特征的参数比例（宽长比及宽度比）。采用SPSS 19.0软件包对数据进行统计学分析。结果: 男性中切牙、尖牙的宽度和长度大于女性,差异有统计学意义（P<0.05）,男性、女性侧切牙的宽度和长度无显著差异（P>0.05）;男性、女性上颌前牙的宽长比值无显著差异（P>0.05）,宽度比值差异有统计学意义（P<0.05）。结论: 临床上应充分考虑患者地区、种族及性别差异,以更好地进行上颌前牙修复。     

A non-invasive method for the assessment of gingival thickness in the aesthetic zone and the concept of the gingival geometric ratio in an Asian population

The aim of this study was to investigate the gingival thickness and biologic width in the aesthetic zone (maxillary central and lateral incisors) in an Asian population using cone beam computed tomography (CBCT) as a non-invasive measurement method, prior to immediate implant placement. The gingival geometric ratio is introduced as a new parameter for assessing soft tissue stability and hence predicting the aesthetic outcome. The gingival thickness, biologic width category (normal, high, and low crest), and gingival geometric ratio (shape and configuration of the gingival tissues) were assessed for 171 central and 175 lateral incisors on high-resolution CBCT images. Thick gingivae were found in 93.6% of the central incisors and 64% of the lateral incisors (P < 0.001). The difference in thickness between the central and lateral incisors was statistically significant (P < 0.001). Regarding the biologic width of the facial gingival tissue, the majority of central (64.8%) and lateral (64.3%) incisors were categorized as low crest (>3 mm). The study found that most of the gingivae of the maxillary central incisors were thick, while thin gingivae were more prevalent in the lateral incisors. Therefore, an individual patient may have different gingival thickness types, and ‘one individual, one gingival biotype’ may not be true. Furthermore, the majority of the facial gingival tissues of the maxillary incisors were found to be low crest.     

Does the canine dental follicle cause resorption of permanent incisor roots? A computed tomographic study of erupting maxillary canines

We performed computed tomography (CT) on 107 children and adolescents aged 9-15 years with 176 unerupted maxillary canines (152 erupting ectopically and 24 erupting normally) to determine whether there is an association between widened dental follicles of the maxillary canines and resorption of the adjacent incisors during eruption. Contiguous axial (transverse) CT scans were obtained through the maxilla in the region of the canines. The width and shape of the dental follicles were recorded, as were any contacts between the follicles and the crowns of the maxillary canines and neighboring incisors. Fifty-eight lateral incisors (38%) and 14 central incisors (9%) had some type of root resorption. The position of the maxillary canine in relation to the root of the lateral incisor varied greatly, as did the width and shape of the canine dental follicle. Follicle width ranged from 0.5 mm to 7.0 mm. The mean +/- SD width of dental follicles was, on average, larger for the ectopically positioned canines (2.9 +/- 0.8 mm) than for the normally erupting canines (2.5 +/- 0.8 mm) (P < or = .01). We found that during eruption, the follicle of the erupting maxillary canine frequently resorbed the periodontal contours of adjacent permanent teeth but not the hard tissues of the roots. We concluded that the dental follicle did not cause root resorption of permanent teeth. Resorption of neighboring permanent teeth during maxillary canine eruption was most probably an effect of the physical contacts between the erupting canine and the adjacent tooth, active pressure during eruption, and cellular activities in the tissues at the contact points, all of which are part of the eruptive mechanism. The findings also confirm an association between root resorption of deciduous canines and the dental follicles of erupting permanent canines.     

Changes in alveolar bone thickness due to retraction of anterior teeth.

In cases of bimaxillary protrusion, extraction of 4 premolars and orthodontic treatment with retraction of the anterior teeth is a widely used approach. However, there is controversy over whether the changes that occur in the anterior alveolar bone always follow the direction and quantity of tooth movement. Nineteen patients with dentoalveolar bimaxillary protrusion treated by extracting the 4 first premolars were evaluated with lateral cephalograms and computed tomography (CT). Cephalograms and CT scans were made before treatment and 3 months after retraction of the incisors. The measurements of the cephalograms showed that maxillary and mandibular incisors were retracted primarily by controlled tipping of the teeth. For all maxillary and mandibular incisors, we assessed the labial and the lingual alveolar plates at crest level (S1), midroot level (S2), and apical level (S3) for bone-thickness changes during retraction of the maxillary and mandibular anterior segments. In the mandibular arch, the labial bone maintained its original thickness, except the S1 measurements, which showed a significant decrease in bone thickness (P <.001). In the maxillary arch, the labial bone thickness remained unchanged. There were statistically significant decreases in lingual bone width in both arches after retracting the incisors. Some of the patients demonstrated bone dehiscence that was not visible macroscopically or cephalometrically. When tooth movement is limited, forcing the tooth against the cortical bone may cause adverse sequelae. This type of approach must be carefully monitored to avoid negative iatrogenic effects.     

The use of regression constants in estimating tooth size in a Negro population.

A study of a sample of 105 Negro children and adolescents, residents of Connecticut, was undertaken to determine the degree of correlation between mandibular tooth size and the size of the canines and premolars. The correlation between the total mesiodistal width of the mandibular permanent incisors and that of the maxillary or mandibular canine and first and second premolars was found to be 0.63 and 0.71, respectively. Further, regression constants were determined in an attempt to estimate the buccal segments from the mandibular incisors.     

Labial-cervical-vertical groove in maxillary permanent incisors--prevalence, severity, and affected soft tissue.

OBJECTIVES: To investigate the prevalence and severity of a labial-cervical-vertical groove (LCVG) in maxillary permanent incisors and its effect on the associated gingival tissue. METHODS: A total of 600 adolescents (293 boys and 307 girls, mean age 13.6+/-1.99 years) were randomly selected and examined for the presence of LCVG. The deformity was classified as mild, moderate, or severe according to predetermined criteria. Gingival coverage at the groove site was defined as normal, partial, and irregular. RESULTS: LCVG was found in 27 adolescents (4.5%). It was unilateral in 24 (89%) and bilateral in 3 (11%). The ratio of central to lateral incisors was 29:1. No sexual dimorphism or side prevalence were found. Mild LCVG was found in 22 incisors, moderate LCVG in 7 incisors, and severe LCVG in one incisor. Moderate LCVG was 5 to 6 times more susceptible to partial or irregular coverage of the gingival margin than mild LCVG. The gingival sulcus in teeth with LCVG demonstrated a significant (P = .001) increase in depth compared to non-LCVG teeth (1.55+/-0.90 mm vs 1.18+/-0.75 mm). CONCLUSIONS: An LCVG is a deformity confined predominantly to a single permanent maxillary central incisor. Its prevalence is not connected with gender. Most LCVGs are mild and often difficult to detect. However, the greater the severity, the more gingival irregularity is associated. This and the increase in sulcus depth in LCVG incisors are adverse predispositions for periodontal sequelae, calling for cautious oral hygiene maintenance.     

颧牙槽嵴区骨宽度及皮质骨厚度的CBCT测量分析

目的:应用锥形束CT(CBCT)测量成年人与青少年的颧牙槽嵴区域的骨宽度、皮质骨厚度及窦底高度,并评价2组的差异,为临床中颧牙槽嵴区微种植体的植入提供参考。方法:选取成年人个别正常牙合志愿者和安氏Ⅰ类青少年患者各30例,获取其口腔颌面部CBCT扫描影像。测量颧牙槽嵴区域的骨宽度、皮质骨厚度及上颌窦底高度,并对测量数据进行统计学分析。结果:两实验组颧牙槽嵴区域均为第二前磨牙和第一磨牙之间的骨宽度最大,且每层的5个测量值均表现为随测量点向颅方移动骨宽度值逐渐减小。两实验组各层颧牙槽嵴区骨宽度与窦底高度成正相关关系。结论:成年人组各位置骨宽度平均值及皮质骨厚度平均值均较青少年组相应位置大。颧牙槽嵴区骨宽度随窦底高度增大而增大。2组样本上颌窦个体差异均非常大,植入微种植体前需拍摄CBCT以确定是否满足植入条件。