吉林通化地区朝鲜族中学生前磨牙畸形中央尖调查

目的：揭示畸形中央尖在朝鲜族人前磨牙中的分布特点及规律。方法：对吉林通化市部分朝鲜族中学生人群（3819人）进行口腔检查,记录畸形中央尖在前磨牙上的发生情况。率的比较采用卡方检验,双侧同名牙间的相关性分析采用Kendall检验,计算相关系数tau及双侧共同发生率。结果：畸形中央尖的个体发生率为3.82%,女性组（4.47%）显著高于男性组（3.15%）（P〈0.05）。畸形中央尖在下颌第一磨牙的构成比（1.45%）高于上颌第一前磨牙（0.41%）,在下颌第二前磨牙（1.88%）要高于上颌第一前磨牙（0.56%）,差异有统计学意义（P〈0.001）。畸形中央尖在上颌第一、二前磨牙及下颌第一、二前磨牙的双侧共同发生率依次为93.75%（15/16）、55.17%（16/29）、63.24%（43/68）和47.42%（46/97）,双侧相关系数tau依次为0.968、0.710、0.771和0.640。结论：掌握掌畸形中央尖的发生规律具有重要的临床价值及人类学意义。     

隐裂154例分析

笔者在门诊遇到确诊的隐裂１５４例，１８４个患牙，分析讨论如下。发病年龄２０～６３岁，以４０～４９岁年龄组发病率最高，占４８．１％，其次为５０～５９岁者。男性７２例、女性８２例，上颌１１９个，下颌６５个，上颌发病率明显高于下颌；第一磨牙１１９个（６４．７％），第二磨牙４４个（２３．９％），第三磨牙７个（３．８％）．第二前磨牙９个（４．９％），第一前磨牙５个（２．７％）。磨牙明显高于前磨牙，第一磨牙发病率最高。隐裂发生的部位及裂向１８４个患牙中裂纹全部或部分与发育沟重迭的１７８个（９６．７％），未与…     

上颌前磨牙牙根及根管形态的锥形束CT研究

目的研究上颌前磨牙牙根形态、三根管的发生率和根管解剖形态,为临床诊疗提供参考。方法选取珠海市口腔医院412名患者,共779颗上颌第一前磨牙,728颗上颌第二前磨牙的锥形束CT(cone-beam computed tomography,CBCT)扫描数据,分析上颌前磨牙的牙根及根管形态,三根管的发生率、双侧对称性、根管分叉位置等。结果上颌第一前磨牙三根管发生率为1.8%,上颌第二前磨牙三根管发生率为0.3%,上颌第一前磨牙三根管发生率显著高于上颌第二前磨牙(X^2=8.304,P=0.004)。上颌第一前磨牙三根管对称率为27.3%,上颌第二前磨牙无对称三根管结构出现。上颌前磨牙解剖形态可为单根、双牙根或三牙根,其内部根管形态复杂,存在七种Vertucci根管类型,上颌第一前磨牙以VertucciⅣ型为主,上颌第二前磨牙则以VertucciⅠ型常见。三根管上颌前磨牙的根管分叉位置多见于根中或根上1/3,16颗三根管上颌前磨牙都具有三个独立的根尖孔。结论上颌前磨牙根管形态复杂多变,CBCT对发现变异和额外根管具有重要辅助作用。     

应用锥形束CT对成人上颌前磨牙牙根和根管系统形态的研究

目的：运用锥形束CT（CBCT）观察中国人群上颌前磨牙的牙根和根管系统的解剖形态,为临床根管治疗提供影像学依据。方法：选择200名患者的双侧上颌前磨牙（上颌第一前磨牙、上颌第二前磨牙各358颗）的CBCT扫描数据,使用NNT软件分析上颌第一、第二前磨牙的牙根数、根管数、根管分型以及双侧对称情况。结果：上颌第一前磨牙主要为单根（65.92%）和双根（33.80%）。上颌第二前磨牙主要为单根（93.85%）。上颌第一前磨牙的根管系统主要为双根管（84.36%）。上颌第二前磨牙的根管系统单、双根管比例接近（分别为52.79%和46.08%）。上颌第一前磨牙主要根管分型为：Ⅳ型（48.32%）、Ⅱ型（24.30%）和Ⅰ型（12.56%）。上颌第二前磨牙主要根管分型为：Ⅰ型（51.68%）、Ⅱ型（21.51%）和Ⅳ型（14.25%）。上颌第一、第二前磨牙的根管分型左右对称（对称率分别为74.57%和81.29%）。上颌前磨牙根管系统的主要变异为：管间交通支、颊根C形根管和多根管（树形根管或神经根样根管）。结论：上颌第一、第二前磨牙的根管系统主要为单根管和双根管。术前了解根管形态的变异是治疗成功的关键因素。     

乌鲁木齐地区汉族中学生前磨牙畸形中央尖调查

对乌鲁木齐市一个汉族中学生人群(3 819人)进行口腔检查,发现畸形中央尖的个体发生率为3.82%,女性组4.47%,男性组3.15%(卡方检验,P<0.05);在下颌第一前磨牙的发生率1.45%,上颌第一前磨牙(0.41%),在下颌第二前磨牙1.88%,上颌第二前磨牙0.56%,差异均具有统计学意义(P<0.001)。畸形中央尖在上颌第一、二前磨牙及下颌第一、二前磨牙的双侧共同发生率依次为93.75%(15/16)、55.17%(16/29)、63.24%(43/68)和47.42%(46/97),Kendall相关系数tau依次为0.968、0.710、0.771和0.640。掌握掌畸形中央尖的发生规律具有重要的临床价值及人类学意义。     

上颌前磨牙根管变异及其与上颌窦关系的锥形束CT研究

目的:利用锥形束CT研究上颌前磨牙牙根及根管系统解剖形态,为临床提供影像学依据。方法:选取720例成人患者（18~67岁）的锥形束CT扫描图像,按年龄分为5组：18~28岁、29~38岁、39~48岁、49~58岁及>58岁组,分析上颌前磨牙牙根及根管数、根管类型、两根管口间距离、根管弯曲度、根尖到上颌窦底距离、左右同名牙的对称性等及与年龄的关系。采用SPSS21.0软件包对数据进行统计学处理。结果:上颌第一前磨牙多为双根管（89.72%）,根管类型以Ⅳ型最常见（57.78%）。上颌第二前磨牙单根管发生率（53.06%）略高于双根管（46.94%）,根管类型以I型（53.06%）为主。左右同名牙牙根及根管数目多为对称分布。上颌前磨牙单根、双根管检出率随年龄变化而变化,两根管口间距离与根管类型关系密切。上颌第一、第二前磨牙颊舌向弯曲的根管检出率分别为32.53%和21.50%,存在S形复杂弯曲根管。16.69%的上颌第二前磨牙与上颌窦为关系密切型（d≤0.05 mm）。结论:上颌前磨牙牙根及根管解剖结构复杂,左右同名牙呈对称性。根管形态、结构和类型存在增龄性变化,根管弯曲情况复杂,牙根与上颌窦关系密切。     

上颌前磨牙颈部宽、厚、曲度的测量分析

目的：手工测量并获取自然上颌前磨牙颈部数据，为上颌前磨牙区种植美学基台研究设计提供基础数据，并为种植修复临床提供参考。方法：采用高精度游标卡尺测量608个离体上颌前磨牙（其中上颌第一前磨牙296个，上颌第二前磨牙312个）颈部宽度和厚度，牙颈曲度，釉牙骨质界（CEJ）下1．5mm颈宽、颈厚；运用SPSS 13．0软件对所测数据作统计学处理。结果：测量并分析得出各指标的均值、标准差、上下四分位间距值。结论：所测数据是对西安地区人前磨牙颈部数据的进一步补充完善，为西安地区上颌前磨牙区牙颈部修复美学、种植体牙龈美学成型基台的设计研发提供数据支持。     

255例牙冠折裂的临床分析

目的分析长期咀嚼过程中牙冠折裂的发生情况,并初步探讨冠折发生的相关因素。方法以2005年12月-2007年12月在兰州市第一人民医院口腔科就诊的255颗冠折牙为研究对象,对折裂牙的患者性别、年龄、牙位、折裂位置及形态等进行分析。结果255颗冠折牙中,1）上颌第一磨牙76颗（29.8%）,下颌第一磨牙45颗（17.6%）,上颌第二磨牙41颗（16.1%）,下颌第二磨牙37颗（14.5%）,上颌第二前磨牙32颗（12.5%）,上颌第一前磨牙15颗（5.9%）,下颌第二前磨牙9颗（3.5%）;2）折裂位置与窝沟重叠者158颗（62.0%）,发生于牙尖斜面者97颗（38.0%）。3）正常者85颗（33.3%）,面形态异常者55颗（21.6%）,型异常者115颗（45.1%）。结论牙位及形态等与牙冠折裂的发生具有一定的关系。力是牙冠折裂的基本因素,但不是唯一因素。     

锥形束CT测量成人上颌前磨牙根尖与上颌窦位置关系及其对即刻种植的影响

目的 分析上颌前磨牙牙根与上颌窦空间位置关系,为该位点即刻种植时机、方案、术式及种植体选择等提供解剖依据。方法 本研究已通过单位伦理委员会审查批准,并获得患者知情同意。收集2017年1月-2023年3月瑞华口腔门诊部就诊的264例患者（年龄20～65岁）口腔锥形束CT(cone beam CT,CBCT)影像,选取冠状面测量上颌前磨牙根尖到上颌窦下壁的最短距离,对牙根与上颌窦下壁的垂直关系分类,并就双侧、性别及不同年龄组进行比较。结果 上颌前磨牙根尖至上颌窦下壁最短距离：上颌第一前磨牙单根型中位数为7.34 mm,双根型颊根中位数为7.80 mm,腭根中位数为7.36 mm;上颌第二前磨牙单根型中位数为2.56 mm,双根型中颊根中位数为1.73 mm,腭根中位数为1.23 mm。上颌第二前磨牙右侧单根型根尖至上颌窦下壁间最短距离在各年龄组间有统计学差异（P<0.05）,20～29岁组最小（中位数1.52 mm）,≥40岁组最大（中位数4.44 mm）。性别和左右侧对根尖到窦下壁距离的影响无统计学差异（P>0.05）。上颌前磨牙根尖与上颌窦垂直关系中,根尖不与上颌窦下壁接触...     

前磨牙拔牙模式对前牙比正常的不同错(牙合)畸形矫治后全牙比的影响

目的：探讨前牙比正常的安氏3种分类经不同的拔牙模式治疗后全牙比的变化。方法：选取252例前牙比正常的患者模型,计算各组拔牙前和模拟4种模式拔牙后的全牙比,了解其变化规律。结果：相同拔牙模式的3种错（牙合）组矫治后的全牙比之间无大的差别;与拔牙前相比较,3种错（牙合）组拔牙后的全牙比均有所减小;在安氏Ⅰ类组与Ⅲ类组中,除了第2组（上下颌均拔除第一前磨牙）与第3组（上颌拔除第一前磨牙,下颌拔除第二前磨牙）,第4组（上颌拔除第二前磨牙,下颌拔除第一前磨牙）与第5组（上下颌均拔除第二前磨牙）间全牙比的比较无显著性统计学差异外,其余组间的比较均有显著性差异;安氏Ⅱ类组,不同拔牙模式的全牙比之间均有显著性统计学差异。结论：前牙比正常的安氏不同错（牙合）畸形进行拔牙矫治时,前磨牙的拔牙模式会对拔牙后的全牙比产生影响。     

Maxillary buccal cortical plate inclination at mini-screw insertion sites

Objective:To evaluate whether buccal cortical bone inclination varies for the maxillary alveolar processes of adult patients with decreased, normal, and increased facial heights.Materials and Methods:Cone-beam computed tomography images of 135 adult patients, including 49 hypodivergent subjects (26 women, 23 men), 40 hyperdivergent subjects (24 women, 16 men), and 46 normodivergent (25 women, 21 men) were analyzed. Cortical bone inclination measurements were made relative to the occlusal plane. Cross-sectional slices of the maxilla were taken at interdental sites from the distal aspect of maxillary canine to the mesial aspect of maxillary second molar.Results:Analysis of variance indicated significant differences (P < .05) between the angles formed by the line tangent to the cortical bone and the occlusal plane among the vertical facial types for the regions between canine and first premolar and between second premolar and first molar at miniscrew insertion sites.Conclusion:The results of this study indicate that vertical facial pattern should be taken into consideration when adjusting the insertion angle of miniscrews at the maxillary buccal region.     

Determination of the physiologic equilibrium point of the mandible by electronic means

The location of the physiologic equilibrium point of the mandible was determined by electronic means while the subjects clenched their teeth in centric relation with a force of 24 pounds. A total of 20 occlusal relationships were observed. In 14 Angle's Class I occlusal relationships, the equilibrium point, when projected at right angles to the midsagittal plane, was observed lined up within the mesial third of the mandibular first molar. In four Angle's Class II occlusal relationships, it was lined up within the distal half of the mandibular second premolar; and in two Class III Angle's occlusal relationships, it was lined up within the middle third of the mandibular first molar. When referenced to the maxillary arch, 16 occlusal relationships lined up within the mesial third of the first molar and four within the distal half of the second premolar. In the coronal plane, the equilibrium point was estimated as being in or close to the midsagittal plane. The biomechanical significance of the equilibrium point was discussed. The location of the equilibrium point was expressed mathematically using a model of the mandible as a beam on resilient supports. Further studies considering the clinical significance of the equilibrium point in relation to centric occlusion registrations and orthodontic treatment are suggested.     

Morphological characteristics of the teeth of Newar children

The morphology of the teeth of Newar children was investigated in order to determine racial characteristics of the teeth in comparison with those of Japanese. The results were as follows. 1) The incidence of a C type labial surface pattern on the maxillary incisors was greater in Newars than Japanese for both the maxillary central and lateral incisors. 2) The total incidence of shovel-shaped and semi-shovel-shaped maxillary incisors was greater than 80% in Japanese, although at most about 25% in Newars. 3) The incidence of interstitial tubercles on the maxillary premolars in Newars was less than in Japanese. 4) The incidence of the cusp of Carabelli on maxillary first molars was greater in Newars than in Japanese. 5) Although the incidence of protostylids on the mandibular first molars was less in Newars than in Japanese, the incidence of the + type occlusal groove pattern was higher in Newars. Even though four-cusp mandibular first molars were more common in Newars than in Japanese, the incidence of a sixth cusp was lower in Newars. Also, the incidence of a sixth cusp was lower in Newars. Also, the incidence of medial of medial lingual accessory tubercles was slightly higher in Newars than in Japanese. Examination of the Newar teeth confirmed previous findings that they are racially Caucasoid, although they have some similarities with Japanese.     

青少年上颌前磨牙邻面形态研究

［摘要］ 目的 建立青少年上颌前磨牙邻面形态数据库,为临床操作和成形片等相关器械的制作及改进提供依据。方法 从安阳市口腔医院CT库中随机选择219例符合纳入标准的患者,调整其图像至要测量的截面并截屏,将截图导入精雕软件（ArtForm 2.0）进行定点并测量邻面上两横三纵5条弧线的曲率半径。结果 除上颌第一前磨牙近中面颈部横向弧的曲率半径为负值（凹面）外,其他部位均为正值（凸面）。男性上颌第二前磨牙近中面3条纵向弧的曲率半径均大于女性。结论 上颌第一前磨牙近中面颈部有凹陷。男性上颌第二前磨牙近中面纵向较女性平坦。     

Treatment and posttreatment changes with combined headgear therapy

OBJECTIVE: To determine the effects of combined headgear treatment in high-angle patients and to evaluate the differences 2 years after treatment. MATERIALS AND METHODS: The study material consisted of lateral cephalograms of 21 patients (13 girls and eight boys; mean age 10 years 3 months) with Class II dental relationship. Only extraoral combined traction that was applied to maxillary first molars was used in the treatment of all patients. The patients were instructed to wear the appliance 20 hours per day until the molar relationship was corrected. The treatment time was approximately 5 months. At the beginning (T0), at the end (T1), and approximately 2 years after (T2) combined headgear treatment, lateral cephalometric radiographs were obtained. RESULTS: SNA and ANB angles and convexity decreased significantly during treatment (T0-T1; P<.05 and P<.01, respectively), and the net changes (T0-T2) in ANB angle and convexity were also found to be statistically significant (P<.01). During treatment, significant distal movement was found in the upper first molar, and the second premolar and molar were also distalized significantly (P<.001). At the end of 2 years, there was a significant mesial migration of the upper molars and the second premolar during the posttreatment period, but all of them were positioned more distally compared to the beginning of treatment (P<.001). The decrease in molar relation was statistically significant during the T0-T1 and T0-T2 periods (P<.001).     

上颌游离端可摘局部义齿修复基牙的三维有限元应力分析

目的：本研究采用三维有限元动态分析法，对上颌游离端可摘局部义齿修复双尖牙基牙进行应力分析。方法：利用工程扫描系统、计算机辅助设计软件和有限元程序，模拟天然牙齿建立三维有限元模型。根据基牙的受力情况制作7种实验模型，并结合He支托的不同设计，常规载荷下，对基牙在近远中、颊舌向和咬合方向进行应力分析。结果：1)游离末端基牙远中牙颈部为最大应力区。2)远中He支托对基牙的损伤较近中殆支托大，He支托设计位置越向近中移动，其对基牙的损伤越小。3)颊舌向外力和近远中方向外力对基牙造成的损害比来自咬合方向明显大。结论：上颌游离可摘局部义齿，使用近中He支托，远中固位臂加远中邻面板的类似设计更有效地减少不良应力对基牙带来的伤害。     

The influence of implant location and length on stress distribution for three-unit implant-supported posterior cantilever fixed partial dentures

STATEMENT OF THE PROBLEM: The influence of implant location for an implant-supported cantilever fixed partial denture (FPD) on stress distribution in the bone has not been sufficiently assessed. PURPOSE: This study examined the influence of location and length of implants on stress distribution for 3-unit posterior FPDs in the posterior mandibular bone. MATERIAL AND METHODS: Each 3-D finite element model included an FPD, mesial and distal implants, and supporting bone. The mesial implant with a length of 10 mm or 12 mm was placed in locations where its long axis was 3 mm to 11 mm posterior to the remaining first premolar. The distal implant with a length of 10 mm was fixed at the same distance from the premolar on each model. A buccally-oriented oblique occlusal force of 100 N was placed on each occlusal surface of the FPD. RESULTS: The maximum equivalent stresses were shown at the cervical region in the cortical bone adjacent to the mesial or the distal implants. Relatively high stresses of up to 73 MPa were shown adjacent to the mesial implant located 9 mm or more posterior to the first premolar. The use of a 12-mm-long mesial implant demonstrated a relatively weak influence on stress reduction. CONCLUSION: The implant location in the cantilever FPDs was a significant factor influencing the stress created in the bone.     

Interproximal papillae reconstruction in maxillary implants

BACKGROUND: Gingival esthetics has become an important factor in the overall success of most maxillary implant-supported restorations. Periodontal plastic surgery procedures may be used to enhance esthetics in the maxillary anterior region. The purpose of the present study was to evaluate a new surgical approach, performed at implant exposure, to reconstruct interdental papillae around maxillary implant-supported restorations. METHODS: The surgical procedure was performed on 32 patients, in which 36 consecutive single tooth osseointegrated implants were exposed in the anterior and premolar maxillary region. Previous to implant exposure and 6 months postoperatively, once the implant-supported restoration was in place, mesial and distal papilla contour measurements were calculated, based on a modification of the papillary index score (PIS). Statistical analysis consisted of paired t test, Pearson's correlation, and ANOVA with repeated measures. RESULTS: Preoperative PIS ranged from 0 to 3 and from 1 to 3 at the 6 months follow-up control. A mean of mesial and distal papilla, within the same tooth, was used for paired t test statistical analysis. A mean increase of 1.07 (SD 0.43) in PIS was statistically significant (P<0.001). At the second measurement, in no site was PIS smaller (0%) while in 64 sites PIS was higher (89%). In 51 papilla (71%) there was an increase of 1 PIS unit and 13 (18%) of 2 PIS units between both measurements. CONCLUSIONS: The presented surgical technique performed at second stage implant surgery was useful for partial or total interproximal papilla reconstruction adjacent to maxillary single-implant restorations.     

Changes in occlusal function after extraction of premolars: 2-year follow-up

Objective:To determine the effects of extraction and the number of teeth extracted on changes in occlusal function by measuring occlusal contact area and force before and after orthodontic treatment with a fixed appliance.Materials and Methods:Female patients treated with a fixed appliance were divided into nonextraction (n = 36), two maxillary premolar extraction (n = 31), and four premolar extraction (n = 18) groups. Bite pressure-sensitive films were used to analyze the occlusal contact area and force. Measurements were performed before treatment (Pre-Tx), immediately afterward (After-Tx), and 2 years later (2Y After-Tx). The data were analyzed using a linear mixed model and the post hoc Bonferroni test.Results:The occlusal contact area and force after treatment decreased significantly compared with Pre-Tx values but were increased 2 years later in all groups. There were no significant differences in occlusal contact area or force during the entire observation period among the three groups (P > .05). The occlusal contact area and force in the nonextraction and two maxillary premolar extraction groups recovered to Pre-Tx levels 2 years later (P > .05). The occlusal contact area in the four premolar extraction group was significantly lower than the Pre-Tx level after 2 years of retention (P < .05).Conclusions:The occlusal contact area and force showed a tendency to decrease immediately after treatment and then gradually increase to pretreatment levels during the observation period. However, the occlusal contact area did not recover fully after 2 years in the four premolar extraction group.