热处理方式对多曲簧开闭口运动力值的影响

目的:研究热处理前后多曲簧在开闭口疲劳运动过程中的应力值、位移量及拐点的变化来为临床正畸提供参考。方法:通过拉伸-拐点-压缩实验模拟颊侧多曲簧矫治器在口内开闭口运动过程中的作用,研究不同热处理方式对应力值的影响。结果:通过多曲簧经先加热后弯制处理,可增大其开闭口运动过程的应力值及拐点位移量,其中480 ℃处理效果最明显。多曲簧先弯制后热处理对其拉压过程中拐点位移量基本没有影响。结论:制作颊侧多曲簧时,牙用不锈钢丝可先经480 ℃热处理后再弯制,可提高机械性能。     

方丝"口字曲"矫正7-颊移位的临床应用(附16例报告)

锁是后牙的一种错(牙合)畸形,7-颊向移位,被锁结在7-的颊侧,在临床上较多见.常规矫治时,在锁结牙上做带环,借助橡皮圈进行颌间交互牵引,有时产生支抗牙移位及影响口腔功能等弊端,为此我们使用方丝"口字曲",取得良好效果.     

钟摆矫治器联合颊侧推簧远移磨牙的疗效分析

目的：评价钟摆矫治器联合颊侧推簧远移磨牙的疗效.方法：选择40例牙性安氏Ⅱ类错（牙合）畸形的患者,随机均分为两组：钟摆矫治器联合颊侧推簧远移磨牙组（组1）和头帽口外弓远移磨牙组（组2）,在治疗开始前（T0）和远移磨牙完成时（T1）分别拍摄侧位头影定位片进行头影测量,t检验分析组内和组间的差异.结果：组1和组2远移磨牙的平均距离分别是（4.48±1.63） mm、（2.68±1.71） mm;组1和组2磨牙远中倾斜的平均角度分别是5.46°±3.23°、1.02°±2.16°;组1上颌中切牙未发生明显的唇倾和唇向移位,而组2上颌中切牙发生了较为明显的腭侧移位.结论：钟摆矫治器联合颊侧推簧远移磨牙可有效防止前牙支抗的丧失、控制磨牙的近中颊侧旋转.     

方丝“口字曲”矫正颊移位的临床应用(附16例报告)

锁牙合是后牙的一种错牙合畸形，７－颊向移位，被锁结在７－的颊侧，在临床上较多见。常规矫治时，在锁结牙上做带环，借助橡皮圈进行颌间交互牵引，有时产生支抗牙移位及影响口腔功能等弊端，为此我们使用方丝“口字曲”，取得良好效果。１临床资料１．１一般资料１６例...     

用切牙斜面导板矫治上颌一个中切牙反的病例

上颌一个中切牙反的病例较常见。应用切牙斜面导板(inclined Plane)来矫治是有效的。这种用自凝树脂制作的斜面导板,制作简单,疗效快,是一般临床工作者乐于采用的装置。适应症只限于替牙列早期上颌一个中切牙的反(牙合)。不适用于二个牙的反(牙合)。若前牙复(牙合)不到2毫米时,矫治时可能形成开(牙合),矫治后容易复发,因而是禁忌的。整个前牙反(牙合)、下颌前突,即有颌关系异常者亦属禁忌。制作方法采用笔刷法把自凝树脂糊塑     

一种新型支抗加强系统的应用及机理分析

介绍了一种可以拆卸的中度正畸矫治支抗加强系统。该系统主要由直径1.2mm的牙用不锈钢丝弯制成的粗唇弓组成,在需要增强支抗的矫治阶段(如尖牙远移、切牙舌移阶段),插入支抗磨牙带环上与之吻合的粗颊侧管内。粗唇弓左右两侧的交互作用以及粗唇弓和颊侧管之间的摩擦力,严格限制了支抗磨牙向近中倾斜及磨牙近中舌向扭转移动,能起到被动支抗加强效能;若在颊侧管近中端给粗唇弓加弯末端内收弯及后倾曲,尚可使磨牙进行支抗预备,即起主动支抗加强效能。粗唇弓前方位于唇系带附着点(牙合)方的口腔前庭,既不压迫牙龈、强撑口唇,也不影响患者外观和口腔功能,口腔不适感小。根据矫治需要可以随时装卸粗唇弓、灵活掌握支抗的大小。实验研究也显示在阻止磨牙近中移动方面,该系统优于腭托及唇挡。     

多曲方丝弓技术矫治恒牙期骨性Ⅲ类错(牙合)的临床分析

目的了解多曲方丝弓技术在骨性Ⅲ类错牙合矫治中的作用机理.方法选择应用多曲方丝弓技术矫治的恒牙期骨性Ⅲ类错牙合患者12例,测量矫治前后的X线头颅侧位片并进行比较.结果矫治后下前牙显著舌向倾斜和远中向移动,上前牙唇向移动.L1-MP平均减少4.10°,L1-NB平均减少2.3 mm,U1-NA平均增加 1.9 mm,U1a-EP平均增加1.1 mm,前牙覆盖和覆牙合平均分别增加4.5 mm和0.8 mm.结论多曲方丝弓技术能有效直立和远中移动磨牙,为下前牙远中移动提供间隙,从而使骨性Ⅲ类错牙合得以成功矫治.     

单侧后牙反的临床矫治

本文对13例单侧后牙反患者的矫治效果进行了小结，认为替牙期可选用活动分裂簧矫治器矫治，方法简单，有效，但患侧后牙颊侧使用翼状导板是一重要措施。恒牙列单侧后牙反矫治过程复杂，应使用方丝弓矫治器为宜。     

上颌单侧后牙舌移位引起反的矫治

目的对上颌单侧后牙舌移位引起反进行矫治.方法22例患者,上颌采用方丝弓矫治器,下颌做全牙列垫,反侧垫颊侧基托与上颌反牙相对应处加牵引钩,上颌反牙舌侧贴牵引扣,上下牙交互牵引.结果反牙近中颊尖颊向移动35.3mm,矫治时间1.54月.反解除,咬合关系好,支抗牙无移位.结论此方法可以提供足够支抗,简单有效.     

带螺圈簧的弓丝在打开咬合时的应用

固定矫治技术治疗牙颌畸形，常常需要打开咬合，咬合打开快慢决定了矫治时间。临床上发现，用国产弓丝弯制后倾曲打开咬合，时间长，有时发生支抗磨牙倾斜和松动。为提高国产弓丝疗效，防止支抗磨牙倾斜，我们在Ｂｅｇｇ矫治技术中，设计带螺圈簧的弓丝打开咬合，治疗牙颌...     

Normal torque of the buccal surface of mandibular teeth and its relationship with bracket positioning: a study in normal occlusion

This study evaluated the degree of buccolingual inclination of mandibular tooth crowns relative to torque. For such purpose, mandibular and maxillary stone casts from 31 Caucasian Brazilian adults with normal occlusion, pleasant facial aspect and no history of previous orthodontic treatment were examined. A custom device was developed for measuring the degree of inclination (torque) of bracket slots of orthodontic appliances relative to the occlusion plane, at three bonding height: standard (center of clinical crown), occlusal (0.5 mm occlusally from standard) and cervical (0.5 mm cervically from standard). Except for the mandibular incisors, which presented a small difference in torque from one another (lingual root torque for central incisors and buccal root torque for lateral incisors), the remaining average values are close to those found in the literature. Due to the convexity of the buccal surface, the 1-mm vertical shift of the brackets from occlusal to cervical affected the values corresponding to the normal torque, in approximately 2 degrees in central and lateral incisors, 3 degrees in canines and 8 degrees in premolars and molars.     

Effect of the inclination of a maxillary central incisor on periodontal stress

Abstract Objective: To determine the effect of labiolingual inclination of a maxillary central incisor on the magnitude and distribution of stresses within the periodontal space. Materials and Methods: Five three-dimensional finite element models of a right maxillary central incisor were created with 0°, 10°, 20°, 30°, and 40° inclination. Each incisor model was subjected to a 1?N lingual-directed force and 6-12?N·mm countertipping moment on the labial surface. The stress level within the periodontal ligament was calculated in terms of maximum principal stresses. Results: With increased inclination, compressive stresses tended to increase whereas tensile stresses tended to decrease. The location where compressive stress was prevalent changed from the midroot area to the apical area on the lingual side, while the area where tensile stresses were predominant changed from the midroot area to the cervical area on the labial side. Conclusion: There are more compressive stresses concentrated at the apex of incisors with a high degree of inclination than in incisors that are more upright. This may be associated with the higher clinical incidence of apical root resorption found in inclined maxillary central incisors.     

A rare case of multiple talon cusps in three siblings

Talon cusp is an uncommon anomaly, whose etiology may be disturbances in the morphodifferentiation stage. Dens in dente is also a rare anomaly that is challenging in clinic as it may cause pulp necrosis or periapical lesions due to the communication with the oral cavity. This article reports multiple talon cusps on permanent maxillary and mandibular incisors and molars in 3 siblings. A 9-year-old boy presented with structures like nodules, shaped as cylindrical cones with a sharp point or a raindrop with deep developmental fissures on the palatal aspect of the maxillary central incisors, lingual aspect of the mandibular central incisors and labial aspect of both mandibular first molars. The buccal surface of the maxillary right central incisor was also affected. Some of them exhibited dens in dente. His 15-year-old sister had prominent talon cusps on the palatal surface of maxillary central incisors and buccal surface of the mandibular first molars and mandibular left second molar. His 7-year-old brother had only one trace talon on the maxillary left central incisor. No syndrome was identified in the patients. In conclusion, genetic inheritance may be a causative factor in talon cusp.     

Change in dentition over 20 years from third decade of life

PurposePrevious studies have documented long-term, age-related change in the teeth, dental arches and occlusion. However, very few studies have investigated longitudinal age-related change in the dentition using 3-dimensional (3-D) measurement. The purpose of this study was to clarify age-related change in the dentition using a laser scanner.Materials and methodsWe used dental casts obtained from the same subjects in their twenties and forties. Subjects were selected based on near-normal occlusion. We investigated age-related variation in the dentition using 3-D measurement.ResultsAge-related change in the dentition was characterized by a decrease in maxillary and mandibular width, an increase in maxillary length, and a decrease in mandibular length. Measurement of angulation revealed that the maxillary canines and molars were mesially inclined. We observed labial inclination of the maxillary incisors, and lingual inclination of the mandibular incisors, as well as the maxillary and mandibular canines and molars. Overjet, overbite, and the irregularity index all showed an increase, while occlusal vertical dimension showed a decrease. Multiple regression analysis indicated that lingual inclination of the lower central incisors was related to an increase in the irregularity index, and that lingual inclination of the upper canines and decrease in occlusal vertical dimension of the anterior teeth were related to increased overbite.ConclusionThe present findings showed that age-related changes in angulation and inclination of each tooth should be taken into account when providing occlusal rehabilitation or post-orthodontic retention.     

成人骨性反(牙合)患者口周肌压力

目的 :研究骨性反牙合患者的口周肌压力特征 ,了解口周肌压力与牙颌形态的相关性。方法 :以 2 0名成人骨性反牙合患者为研究对象 ,检测了姿势位时上下切牙区、尖牙区、磨牙区颊 (唇 )舌侧口周肌压力。结果 :与对照组相比 ,除了上下磨牙区舌侧口周肌压力外 ,骨性反牙合组中的口周肌压力大于对照组中对应区域口周肌压力 (P <0 .0 1)。骨性反牙合患者同一牙弓内左右两侧口周肌压力值无显著性差异 ,各测量区域颊侧压力均大于相应部位的舌侧压力 (P <0 .0 1) ;除了尖牙区唇侧外 ,上下对应区域口周肌压力下颌大于上颌 (P <0 .0 1) ;各牙位口周肌压力中 ,下颌唇侧的口周肌压力最大 (P <0 .0 1)。结论 :牙颌形态影响口周肌压力的大小 ,骨性反牙合患者口周肌压力的最显著的特征为姿势位时下切牙唇侧肌压力值最大。     

Combined use of miniscrews and continuous arch for intrusive root movement of incisors in Class II division 2 with gummy smile

Adequate intrusion and torque control of the retroclined maxillary incisors are critical for the treatment of Class II division 2 (div2) malocclusion. In addition, anterior retraction via lingual root movement can be challenging. This case report demonstrates a combined use of miniscrews and continuous arch with additional torque for intrusion, retraction, and torque control of maxillary incisors in the Class II div2 with gummy smile. A 20-year-old woman presented with multiple issues, including impacted canine, lip protrusion, prolonged retained mandibular primary molar, and two missing maxillary premolars. In order to improve her facial profile and eliminate the need for prosthetic work, the mandibular primary molar and contralateral premolar were extracted. Two miniscrews were placed at the maxillary buccal alveolar bone to apply the posterosuperior force for retraction of anterior teeth, with additional labial crown torque on the arch wire. The results were the intrusion (4 mm) and lingual root movement (17°) of the maxillary incisors without anchorage loss of maxillary molars, flattening of the Curve of Spee, and Class I molar relation that were maintained after 50 months of retention period. The combined use of miniscrews and continuous arch could be a reliable and effective treatment modality for torque control and intrusion of retroclined maxillary incisors in the Class II div2 patient.     

下颌中切牙唇倾度与牙槽骨厚度关系的锥形束CT分析

目的应用锥形束CT（CBCT）测量分析下颌中切牙不同唇倾度与牙槽骨厚度的关系。方法选择60例患者的头颅侧位片和CBCT影像资料,按照下颌中切牙-下颌平面角（L1-MP）分为3组,即舌倾组L1-MP<85.6°;正常组L1-MP为85.6°~99.6°;唇倾组L1-MP>99.6°。三维重建CBCT,在矢状面图像上沿下颌中切牙长轴,选择牙槽骨截面最大的图像,将牙根从釉牙骨质界到根尖点平均分为4段,测量唇、舌侧牙槽骨厚度并合计得到总厚度,观察计数骨开窗及骨开裂发生情况。采用SPSS17.0软件包对数据进行统计学分析。结果舌侧及总牙槽骨厚度在各测量位点间的差异均有统计学意义。根中1/2、根尖1/4及根尖处牙槽骨厚度唇侧均小于舌侧。舌侧牙槽骨厚度在各测量位点均为舌倾组小于唇倾组, 牙槽骨总厚度在根尖、根尖1/4、根中1/2处舌倾组比唇倾组薄。唇倾组和舌倾组的骨开裂发生率均高于正常组,差异显著(P<0.05)。结论下颌中切牙舌侧及总牙槽骨厚度从根尖区到根颈区逐渐变小,舌倾组舌侧及牙槽骨总厚度比唇倾组薄,下颌中切牙牙轴过度唇倾或舌倾易发生骨开裂。     

Alveolar bone changes in maxillary and mandibular anterior teeth during orthodontic treatment: A systematic review and meta-analysis

The association between tooth movement and remodelling of surrounding bone is controversial. To analyse the effect of tooth movement on alveolar bone changes in maxillary and mandibular anterior teeth by cone-beam computed tomography (CBCT). The Embase, Cochrane Library and Medline databases were searched without any language restrictions. Longitudinal studies using CBCT to observe alveolar bone changes of maxillary and mandibular anterior teeth during orthodontic treatment were included. Two independent reviewers performed the study selection, data extraction and methodological quality assessment. A total of 26 studies were included in this review, 14 of which were eligible for quantitative synthesis. In extraction cases, meta-analysis showed vertical bone loss on the labial (0.36 mm) and lingual (0.94 mm) sides of maxillary incisors, and lingual bone thickness decreased significantly at the cervical level (0.57 mm). In non-extraction cases, vertical alveolar bone loss was significant on the labial side (0.97 mm) and lingual side (0.86 mm) of mandibular incisors. Subgroup analysis for skeletal class III patients indicated that vertical alveolar bone loss was 1.16 mm on the labial side and 0.83 mm on the lingual side of mandibular incisors. The absence of high-quality studies and the high heterogeneity of the included studies were limitations of this systematic review and meta-analysis. Based on limited evidence, alveolar bone height and thickness, especially at the cervical level, decreased during both labial and lingual movement of anterior teeth.     

Pulpal anaesthesia for mandibular central incisor teeth: a comparison of infiltration and intraligamentary injections

AIM: This study compared the anaesthetic efficacy of infiltration and intraligamentary injections in the permanent mandibular central incisor. METHODOLOGY: Twelve healthy volunteers received each of the following methods of anaesthesia for one of their mandibular central incisors over four visits. 1 Labial infiltration of 1.0 mL. 2 Lingual infiltration of 1.0 mL. 3 Labial infiltration of 0.5 mL plus lingual infiltration of 0.5 mL. 4 Intraligamentary injection of (118 mL.Two percent lidocaine with 1: 80 000 adrenaline and 30 gauge needles were used throughout. Electrical pulp testing was performed before injection and every 2 min up to 30 min after the injection. Injection discomfort was recorded on a 100-mm visual analogue scale. Data were compared with ANOVA, Student's t-test and chi2 tests. RESULTS: Anaesthesia varied between techniques(F = 9.3, P < 0.001). The incidence of anaesthesia at any time was as follows: 50% success for labial infiltration; 50% success for lingual infiltration: 92% success for combined labial and lingual infiltration; 0% success for intraligamentary injections (chi2 = 20; P < 0.001).The mean (+/-SD) VAS score for intraligamentary injection discomfort was 28 +/- 12 mm, for buccal infiltrations 17 +/- 8 mm and for lingual infiltrations 16 +16 mm. Intraligamentary injections were more uncomfortable than buccal (t = 3.7: P < 0.01) and lingual infiltrations (t = 2.67: P < 0.05). CONCLUSIONS: The most reliable method of the techniques investigated for obtaining pulpal anaesthesia in mandibular permanent central incisors was a combination of labial and lingual infiltration. Intraligamentary injections were unreliable and were more uncomfortable than infiltrations in the mandibular central incisor region.     

An in vitro investigation of lingual bonding

An in vitro investigation was undertaken to evaluate the bonding of orthodontic appliances onto lingual surfaces; 53 maxillary premolars, 37 mandibular premolars, and 37 mandibular incisors were used. Brackets were bonded onto the lingual and labial surfaces and fractured with an Instron machine. Enamel damage associated with debonding also was assessed. Results indicated comparable bond strengths (t test) on lingual (Li) and labial (La) surfaces: maxillary premolars--Li-138.2 kg/cm2, La-127.7 kg/cm2; mandibular premolars--Li-136.2 kg/cm2, La-121.6 kg/cm2; and mandibular incisors--Li-166.3 kg/cm2, La-161.1 kg/cm2. Adaptation of lingual bracket bases resulted in significantly higher lingual bond strengths for maxillary premolars (166.9 kg/cm2) and mandibular premolars (180.4 kg/cm2), but not for mandibular incisors (149.2 kg/cm2). On debonding, the percentages of lingual surfaces exhibiting horizontal "crescent-shaped" fracture lines and enamel fragment fractures were significantly higher (x2 test) than the corresponding percentages for labial surfaces: maxillary premolars--Li-67.9%, La-5.7%; mandibular premolars--Li-62.2%, La-13.5%; and mandibular incisors--Li-43.2%, La-18.9%. Furthermore, an increase in vertical enamel fracture lines (cracks) subsequent to debonding was seen labially and lingually. Bonding procedures for lingual surfaces should be identical to those advocated for labial surfaces. Care during debonding must be exercised to eliminate possible enamel damage.