多曲余弦函数模拟上颌前部弓形宽度、深度和弧长之间的相互关系

目的：探讨上颌尖牙间宽度（W）、前牙弓深度（D）与前牙弓周长（L）之间的相互关系及其对咬合的影响。方法t利用多曲余弦函数描述前部牙弓的形态,建立数学模型来编程计算三者间的关系。结果：在D不变时,W每增加1mm将提供约0．8mm的L;D每减小或增大1mm,需要W增大或减小约1．8—2．0mm;在一定程度上,上下牙量的不调可通过调整W来缓解、消除。结论：在精细调整阶段,应注意W、D与L之间相互关系的变化对最终良好殆关系建立的影响。     

前牙及牙弓前部形态的研究

对湖南地区５０４例成人前牙牙冠形态、牙弓前部形态，前牙的覆Ｙｅ、覆盖、前庭沟的深度进行了直接测量，并进行了统计学分析。其结果为口腔修复临床恢复牙列的正常形态、前牙的正畸、美容、人工前牙的设计、有牙颌托盘的设计提供了参考数据。     

牙弓形态及其影响因素

牙弓型是对牙弓形态的完整描述,包括牙弓大小和形状两方面。—般认为牙弓型受基骨结构、牙萌出顺序、口周肌肉系统及口内功能力的影响[1] 。在颅面部生长发育过程中,软硬组织结构的改变会持续影响牙弓型;同时不同的种族、地域、历史年代,牙弓型有很大差异。现就近年来有关牙弓型及其影响因素的研究作一综述。一、牙弓型方程早期阶段,牙弓曲线被描述为椭圆形、抛物线形、U形、两端固定的链形,并用多种曲线匹配数学模型来重建,如抛物线方程、十椭圆方程、链形曲线方程,圆锥截面曲线方程[2 ] ,但都未能对成人牙弓型作出完整准确的表述。Stanle…     

广西壮族青少年舌侧弓形研究

目的得出壮族正常[牙合]青少年的舌侧弓形图并分析其舌侧弓形特点。方法测量广西壮族正常耠青少年的60副牙[牙合]模型（男女各30副）得出其舌侧牙弓宽度、长度的均值及标准差，测量结果进行统计学处理并绘制其舌侧弓形图。结果壮族青少年舌侧牙弓宽度均男性大于女性，除尖牙区外均有显著性差异（P〈0．05），而长度绝大多数测量值无显著性差异（P〉0．05）。壮族青少年的舌侧牙弓形态无论男女前牙区均较平，牙弓长度相对短。结论壮族青少年的舌侧牙弓形态有其独特特征，临床矫治时应考虑本地区的特点。     

前部弓形的大小变化对Bolton分析预测最终(牙合)关系准确性的影响

目的:探讨前部弓形的大小变化是否对Bolton分析预测最终关系的准确性产生影响。方法:利用数学模型来模拟。结果:随着上下前部弓形尺寸的增大,则上颌牙量相对不足。要达到半径改变前后上下尖牙矢向位置关系的一致,前牙比应变小,反之亦然。结论:Bolton分析对预测最终的良好关系是有一定的局限,受前部弓形的大小变化影响。     

半坡博物馆馆藏六千年前人类牙弓形态研究

目的：通过对西安半坡出土6000年前新石器时期人颌骨的相关研究,了解该时期人的牙弓特征.方法：选取保存较完整的上颌骨94个,下颌骨98个.对牙弓进行三维测量,并对牙弓形态进行观测.结果：报告了该批次标本上下颌牙弓形态的各项测量数据及非测量性状的观测结果.牙弓形态主要以椭圆形为主,Terra牙列指数分析上下牙弓均大于现代人,上颌牙弓宽度变化更为明显.结论：为进一步研究人类颌骨演化积累数据资料.     

西安地区乳前牙反He牙弓形态特征的研究

通过对西安地区６０名乳前牙反Ｈｄ有１３０名乳牙正常Ｈｅ牙弓形态特征的调查结果显示：反Ｈｅ组上牙弓长度及宽度均小于正常Ｈｅ组，下牙弓则大于正常Ｈｅ组，长度的差异程度较宽度明显。牙间隙上牙列较正常Ｈｅ组少，下列较正常Ｈｅ组多。     

骨性Ⅲ类错牙合患者牙弓形态特征分析

目的探讨骨性Ⅲ类错患者的牙弓形态特征,为临床诊断和治疗提供理论依据。方法选择骨性Ⅲ类错患者47例为实验组,个别正常50例为对照组,在石膏模型上测量与牙弓形态特征相关的7个项目,计算上下颌相应测量项目之差,采用SPSS 17.0软件对数据进行独立样本t检验。结果实验组的上颌牙弓前段长度小于对照组,上颌尖牙角大于对照组（P<0.05）;男性实验组的上下颌第一前磨牙间宽度之差大于对照组,牙弓前段长度之差小于对照组（P<0.05）。结论骨性Ⅲ类错患者的牙弓宽度基本正常,但牙弓前段长度不足,且前段弓形较为平直。     

固定包绕式螺旋扩弓器扩弓对牙弓长度的影响

目的研究固定包绕式螺旋扩弓器扩弓前后牙弓宽度、长度变化及两者间的关系。方法选取上牙弓狭窄患者33例,戴用固定包绕式螺旋扩弓器扩大上牙弓,在扩弓前后的上颌石膏模型上测量牙弓宽度变化和牙弓长度变化。结果扩弓前后牙弓宽度增值为4.58±1.23mm,牙弓长度增值5.64±1.35mm。结论使用固定包绕式螺旋扩弓器扩大上牙弓后,牙弓长度增值大于牙弓宽度增值。     

不同拔牙正畸模式牙弓形态变化的研究

目的 探讨不同拔牙正畸模式下,成人牙弓形态变化的规律.方法 选40例拔牙正畸病例,分为G1组20例:拔除四颗第一前磨牙,其中男13例,女7例,平均22岁;G2组20例:拔除四颗第二前磨牙,其中男8例,女12例,平均24岁.用模型测量观察矫治前后牙弓长度及尖牙区、前磨牙区和磨牙区宽度;用X线头影测量观察矫治前后切牙内收及...     

应用Quick自锁托槽系统矫治上颌牙列拥挤的牙弓测量分析

目的 探讨Quick自锁托槽系统非拔牙矫治上颌牙列拥挤病例的牙弓变化特征。方法 选取37例上颌牙列轻到中度拥挤的正畸患者,使用Quick自锁托槽系统进行非拔牙矫治。对治疗前和上颌牙列排齐整平时的研究模型进行多项指标测量。应用SPSS 12.0统计软件分析治疗前后上颌牙弓宽度、牙弓长度及周长的变化。结果 上颌牙列排齐后与治疗前阶段相比,牙弓长度、周长、前磨牙间宽度和第一磨牙间宽度均显著增加,尖牙间宽度和第二磨牙间宽度无显著变化。结论 对于上颌牙列轻到中度拥挤的患者,在应用Quick自锁托槽系统排齐和整平牙列的初期,就可使上颌牙弓宽度、牙弓长度及周长均显著增大,扩大临床不拔牙矫治的范围。?     

上颌牙弓形态的主要要素分析

目的:寻找一种快速评价牙弓形态的客观标准。方法:从396副(年龄:18～26岁;男性257副,女性139副)牙模型中选出62副(男性36副,女性26副)具有正常牙列及牙合的模型,设定以下参考点:切嵴的中点,尖牙的牙尖顶,前磨牙的颊尖,第一和第二磨牙的近中颊尖,以及I1R-I1L连线的中点(A)。从A作一个垂直线与M2R-M2L连线相交,形成参考点(B)。A-B连线与CR-CL连线相交,形成参考点(E)。进行以下分析:(1)评价尖牙的突度,指标为①:角I2R-CR-P1R(∠R)+角I2L-CL-P1L(∠L);(2)评价前牙的曲度,指标为②:(A-B)/(CR-CL),③:180°-∠(CR-A-CL)和④:(A-E)/(CR-CL);(3)评价牙弓长度与宽度比,指标为⑤:(A-B)/(M2R-M2L);(4)评价牙弓的圆润程度,指标为⑥:(rθ5-rθ4)R+(rθ5-rθ4)L;(5)通过双侧后牙参考点连线⑦:P1-P2-M1-M2(线i)、P1-M2(线ii)的形态和位置评价Ⅰ型和Ⅱ型方圆形牙弓的特征。其中指标①、②、③、④、⑤和⑥的数据经过分析归纳为3个主要要素:①前牙的弯曲度,②牙弓的突度,和③牙弓的长-宽比。结果:(1)60%的上颌牙列为方圆形牙弓,没有明显显示出主要要素的形态特征;(2)正方形上颌牙弓的参数①∠R+∠L明显较小;(3)圆形牙弓的特征是参数⑥(rθ5-rθ4)R+(rθ5-rθ4)L值偏小;(4)尖圆形牙弓的参数②,③和④值较大。结论:上述评价参数可以归类为3种主要要素(第1要素、第2要素、第3要素),通过分析这些要素,可以有效地评价上颌牙弓的形态,并得出了3类牙弓的各自形态特征。     

不同自锁托槽矫治系统在治疗早期引起上牙弓变化的研究

目的:分析比较用3 种不同的自锁托槽矫治系统治疗后,在治疗的早期上牙弓的宽度和牙弓周长的变化.方法:选择3 组轻度拥挤的病例,每组15 人,分别使用Damon自锁托槽矫治系统、Smart-clip自锁托槽矫治系统、Tomy自锁托槽矫治系统进行治疗.结果:前磨牙间和尖牙间牙弓的宽度和牙弓周长均显著增加.牙弓周长的增加与治疗前的牙弓周长显著相关.牙弓长度无显著改变.结论:自锁托槽矫治系统在治疗的早期可以显著增加上牙弓的宽度和牙弓周长,各自锁托槽矫治系统之间无显著性差异.     

Determinant factors of Yemeni maxillary arch dimensions

Objective

Information about maxillary arch and palatal dimensions in human populations is important for clinical orthodontics. This study was conducted to assess the determinants of maxillary arch dimensions in a sample of Yemeni individuals aged 18–25 years.

Materials and Methods

The study sample comprised 214/765 adults (101 women, 113 men) who underwent clinical examination and fulfilled the study criteria. Study models were constructed and evaluated to measure maxillary arch and palatal dimensions.

Results

The majority of mean maxillary arch dimensions were significantly greater in men than in women, with inter–second molar distance showing the greatest difference and palatal depth showing the least difference.

Conclusion

Measurements of palatal depth and relationships of the canines to one another and to other teeth thus had the widest ranges, implying that these dimensions are the strongest determinants of maxillary arch size.     

A prospective clinical trial of the effects produced by the Connecticut intrusion arch on the maxillary dental arch

ObjectiveTo assess and compare the effects produced in the maxillary dental arch by means of Connecticut intrusion arch (CIA) with or without a cinch back on the distal end of the tube of the first molars.Materials and MethodsThis study included 44 patients with a mean age of 13.1 ± 1.8 years treated for deep bite with a CIA randomly divided into two groups: group 1 (G1), 22 patients with initial mean age of 12.72 ± 1.74 years treated with the CIA in the upper arch without a cinch back on the distal surface of the tube of the first molars, and group 2 (G2), 22 patients with an initial mean age of 13.67 ± 2.03 years treated with the CIA with a cinch back. Lateral cephalograms were available before treatment (T1) and after intrusion of maxillary incisors (T2). The mean treatment period was 5.5 ± 1.45 months. Intragroup and intergroup changes in the maxillary incisor and molar positions were analyzed by paired and independent t-tests associated with the Holm-Bonferroni correction method for multiple comparisons (P < .05).ResultsThere were significant differences between groups in terms of maxillary incisor displacement. The maxillary incisors flared labially (2.17°) and proclined (1.68 mm) in group 1, whereas a palatal inclination (−1.99°) and retroclination (−1.13 mm) was observed in group 2. No significant differences were found for the molar positions between the groups.ConclusionsThe presence or absence of a distal bend in CIA affects incisor tipping and proclination during intrusion mechanics.     

利用锥形束CT研究单侧上颌尖牙埋伏阻生患者牙弓形态特点

目的 利用锥形束CT(Cone beam computed tomography,CBCT)研究单侧上颌尖牙埋伏阻生患者牙弓形态特点,为研究其病因及预防继发病症提供参考.方法 39名单侧上颌尖牙埋伏阻生患者,其中腭侧埋伏19名,唇侧埋伏20名,另设正常对照20名.三组患者年龄无显著性差异.三组患者拍摄CBCT并对牙弓的影像进行测量,比较三组之间以及阻生侧与非阻生侧的牙弓形态特点.结果 尖牙阻生患者的双侧牙弓比较显示,阻生侧前段及整侧牙弓长度均比非阻生侧小(P＜0.001).腭侧组第一磨牙到腭中缝距离(24.06±1.68) mm小于唇侧组(24.86±1.31)mm和对照组(24.88±1.12) mm,腭侧组牙弓周长(72.29±3.50) mm小于唇侧组(75.96±5.26) mm,P＜0.05.结论 上颌尖牙埋伏阻生可能与牙弓长度(尤其是前段)较短有关,且腭侧阻生可能还与牙弓宽度较小有关.     

Bolton tooth size ratio and its relation with arch widths,arch length and arch perimeter: A cone beam computed tomography (CBCT) study

Objective. The prime aim of the study was to measure and compare the 3D CBCT Bolton tooth size ratio in relation to the upper and lower arch widths, arch length and arch perimeter. Materials and methods. The data source was CBCT high volumetric data from the archives. Tooth size, arch widths, arch length and arch perimeter were measured in maxilla and mandibular arches. The independent t-test and ANOVA were used for statistical analyses. Results. The female Bolton anterior ratio (BAR) (78.373) and Bolton overall ratio (BOR) (93.231) show a greater tooth size ratio in comparison to male BAR (77.162) and BOR (93.124), respectively. However, no significant difference was found in the sexual comparison of all the measurements. Tooth size ratio in arch width groups also showed no significant difference. Significant discrepancies in the arch length (p < 0.05) groups and overall ratio and in the arch perimeter groups (p < 0.05 and p < 0.01) and anterior ratio were revealed. Conclusions. Tooth size ratios during orthodontic treatment for different arch length and arch perimeter groups need to be evaluated carefully.