Dynamic Functional Force Measurements on an Anterior Bite Plane during the Night

BACKGROUND: Anterior bite planes are used in removable and fixed appliance treatment. In removable appliance treatment the question arising is whether the delivered forces can achieve active intrusion in terms of their amplitude and duration. In fixed appliance treatment, the force effect on the incisors and associated pathologic side effects, in particular under the application of intrusion mechanics, have to be considered. SUBJECTS AND METHOD: The aim of the present study was to investigate the effects of an anterior bite plane during the night. For this purpose ten subjects underwent nocturnal sleep investigations by means of a telemetric system. A silicon force sensor was integrated into an anterior bite plane for continuous measurement of bite forces and of the frequency of occlusal contact with the plate. RESULTS: The occlusal forces exerted on the anterior bite planes ranged between 3 and 80 N. The average forces were 5.5-24 N. The number of occlusal contacts varied between 39 and 558, with forces of between 7 and 9 N being registered in most cases. Major interindividual differences were detected in the magnitude of the force as well as in bite frequency. The intraindividual pattern of arising occlusal forces showed an intermittent force effect. No significant differences were found with regard to gender or growth pattern. CONCLUSIONS: In subjects with removable appliances, no active intrusion of teeth is possible during the night owing to the small number of occlusal contacts. Due to the partially very high forces in fixed appliance therapy, the integration of an anterior bite plane has to be assessed as critical in patients with unfavorable root geometry or bruxism.     

Testing force systems and biomechanics--measured tooth movements from differential moment closing loops

Orthodontic tooth movement can be compared to a stimulus-response model, where the stimulus is the applied force system and the response is the resulting tooth movement. Although the principles of mechanics have been applied to orthodontic appliance design, the expression of treatment responses to the force systems is less well known. The purpose of this study was to compare measured tooth movements with the theoretical force system exerted by differential moment closing loops. Sixteen subjects requiring maximum posterior anchorage control were selected to participate in this prospective investigation. T-loop springs designed to deliver a differential moment-to-force ratio to the posterior vs the anterior teeth were used. Initial cephalometric radiographs were taken with special devices attached to the molar and canine teeth to allow precise identification. Immediately after the radiograph, the T-loop archwires were inserted and activated. After an observation period of approximately 90 days, the wires were removed, devices reinserted into the molars and canines, and a second cephalometric radiograph was obtained. Superimposition techniques were used to compare the actual tooth movements. The results showed tooth movements consistent with the prescribed force system. The anterior teeth, as represented by the canines, were retracted an average of 1.73 mm, whereas the posterior anchorage (molars) moved mesially only 0.50 mm. Furthermore, the canine teeth exhibited tipping or translation, and the molars showed mesial root movement. The variability of the treatment response as a function of the stimulus (appliance design), response (biological variation), and measurement technique was described.     

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目的采用三维有限元法模拟不同方向牵引力内收上前牙,分析前牙位移趋势及应力分布,为临床治疗提供指导。方法研究于2012年在福建医科大学进行。建立唇侧直丝弓矫治器、6个上前牙及其牙周膜和前颌骨的三维有限元模型。模拟在0.48 mm×0.64 mm英寸主弓丝上,以种植钉为支抗、1.47 N矫治力整体内收上前牙,设定前牙区牵引钩为0-6 mm、后牙区种植钉高度分别为8和14 mm。加载后求解,计算出各前牙的位移及牙周膜第一主应力。结果滑动法整体内收上前牙时,牵引钩长度主要影响前牙的矢状向位移方式：牵引钩长度增加至6 mm的过程中,侧切牙在唇舌向上由舌向倾斜运动变为舌向整体平移和舌向控根运动外,中切牙和尖牙的三维位移只有数量的增大,趋势基本保持不变。支抗种植钉高度主要影响前牙垂直向位移：种植钉位置越高,侧切牙的压低位移增大,尖牙的伸长位移减小,即前牙整体压低的趋势更明显。结论种植支抗整体内收前牙时,单纯调整牵引钩长度和支抗种植钉高度难以实现前牙段的整体内收,有必要对前牙段增加适当的垂直向压低力量。     

Molar Intrusion with Implants Using a Bite Plane Appliance: A Case Report

Background: Orthodontic forces for tooth intrusion ought to be continuous and low, which may be achieved with the help of osseointegrated implants. Purpose: The aims of this study were to describe a method to intrude supererupted maxillary molars using interarch intrusion mechanics (a bite plane appliance) with implants and to assess anchor implant stability through resonance frequency analysis (RFA; Osstell?, Mentor version 2, Integration Diagnostics AB, Göteborg, Sweden) in comparison with nonanchorage control implants during orthodontic intrusion. Materials and Methods: A 48‐year‐old female patient was treated with implants (36 and 37 regions, Brånemark Implant System®, MkIII TiUNite?, Nobel Biocare AB, Göteborg, Sweden; lengths, 13 and 10 mm; diameter, 5 mm) serving as orthodontic anchorage for intrusion of supraerupted teeth in the maxilla (teeth 26 and 27) using a bite plane appliance. The force of intrusion applied was individual discontinuous bite force in the present case. The control implants were in the sites 45, 46, and 47 with healing abutments out of loading. Stability of both the anchorage and control implants was assessed by RFA from the commencement of orthodontic intrusion (7 months after the first‐stage surgery) to the end of the study (19 months after the first‐stage surgery). Marginal bone height measurements of both implants were performed on radiographs at the same time. Results: The treatment was completed without complications or abnormalities of the intruded teeth or the opposite anchorage implants. However, implant stability quotient values of the anchored implants obviously changed during the initial 4 months after commencement of intrusion compared with control implants. In the present case, an intrusion of 2.2 mm was achieved in 12 months. Conclusions: The present method made it possible to intrude molars successfully. However, further studies with more cases are needed to clarify the reliability of the method and determine how to control the bite forces applied as orthodontic load.     

Deep overbite correction: Biomechanics and clinical implications

The goal of this paper is to describe and discuss the clinical use of intrusion mechanics during orthodontic therapy. The biomechanics of the classic segmented intrusion arch is explored along with modification of the appliance design to intrude and retract anterior teeth simultaneously. The advantages and limitations of intrusion mechanics are presented and the side effects analyzed to avoid undesired tooth movement and optimize clinical outcomes. The implications for the esthetic of the smile and the retention of intrusion are also discussed.     

双侧推磨牙摆式矫治器的临床应用

目的：制作一种双侧推磨牙摆式矫治器,并应用于安氏Ⅱ类错牙合 并伴有牙源性前牙拥挤的患者的治疗。方法：选取15例（男6例,女9例）安氏Ⅱ类错牙合 并伴有牙源性前牙拥挤的患者配戴双侧推磨牙摆式矫治器半年,对矫治前后的头颅侧位片和模型进行测量分析,其测量项目主要包括磨牙远移的距离、磨牙压低的量、磨牙颊舌侧的偏移量、磨牙的近远中倾斜度、U1-SN值以及前牙覆盖量。测量的数据用t检验统计方法 ,并用SPSS17.0软件进行统计学处理。结果：临床观察双侧推磨牙摆式矫治器对安氏Ⅱ类错牙合 并伴有牙源性前牙拥挤的患者疗效显著。统计数据显示：磨牙远移的距离、磨牙压低的量、磨牙颊舌侧的偏移量以及磨牙的近远中倾斜度矫治前后比较差异有统计学意义（P＜0.05）;U1-SN值以及前牙覆盖量矫治前后比较差异无统计学意义（P＞0.05）;不同性别矫治前后比较差异无统计学意义（P＞0.05）。与临床观察基本一致。结论：该双侧推磨牙摆式矫治器治疗安氏Ⅱ类错牙合 并伴有牙源性前牙拥挤的患者,磨牙远移量改变明显,对面高的控制较好,保护了前牙支抗,防止了磨牙的旋转及颊舌侧倾斜,疗效显著且与性别无关。     

Orthodontic treatment in adults with compromised periodontium: biomechanical principles and clinical applications

In recent years, there has been a dramatic increase in the number of adults receiving comprehensive orthodontic treatment. In clinical practice, management of adults may be somewhat different than for most adolescents. Adults are more likely than adolescents to have dentitions that have undergone some degree of mutilation over time, which may necessitate alterations in the treatment strategy. Excessive wear, missing and compromised teeth are some of the differences observed. For adult patients who have experienced bone and attachment loss as a consequence of periodontal disease, a new set of biomechanical requirements exists for producing the tooth movements desired during the orthodontic therapy. Proper planning and appliance design for adults presenting with multiple missing teeth may require some degree of creativity to adapt to unique malocclusions and deliver the proper biomechanical force system. In this article, current clinical application of biomechanical principles will be presented with emphasis on clinical orthodontic management of severely mutilated dentitions.     

微螺钉种植体支抗压低上前牙改善露龈笑临床研究

目的：探讨微螺钉种植体支抗压低上前牙改善露龈笑临床疗效。方法：选择10例深覆牙合,露龈笑病例,男4例,女6例,均采用直丝弓矫治技术。位于12,22远中根尖处颌骨内,种植直径1.5mm,长9mm微螺钉,在方丝12,22远中置游离拉钩,向微螺钉种植体做弹性牵引,每侧70g力,持续牵引5个月。通过治疗前后头颅定位片测量数据,U1-PP,U1-SN,U6-PP,U6-SN,上唇长度ULL,上唇突度ULP,对数据进行T检验。结果：U1-PP,U1-SN显著减小,U6-PP,U6-SN增大,上唇长度ULL增大,上唇突度ULP减小。结论：微螺钉种植体支抗是压低上前牙改善露龈笑的有效方法。     

新型压低下颌磨牙矫治器的临床应用

目的 评估新型压低下颌磨牙矫治器压低下颌磨牙的疗效及应用价值.方法 选择7例需要压低下颌磨牙治疗的前牙开患者,治疗前、后通过临床检查、牙颌模型分析及采用Winceph7.0数字化X线片分析软件测量头颅侧位片,评价临床压入效果,使用SPSS 17.0统计软件包对数据进行分析.结果 7例患者经过平均4个月的治疗,均取得比较明显的治疗效果.治疗前、后头影测量分析表明:下颌第一磨牙的平均压入量为(1.92±0.44)mm,矫治前、后相对于基准平面(MP平面)的垂直距离差异有统计学意义(P<0.05).上颌第一磨牙平均压入量为(0.36±0.25)mm,矫治前、后相对于基准平面(PP平面)的垂直距离差异没有统计学意义(P>0.05).X片显示被压低的下颌磨牙未出现明显的牙根吸收.结论 新型下颌磨牙压低矫治器用于压入下颌磨牙治疗前牙开畸形效果明显,压入治疗未引起明显的牙周及牙根损害.     

微创牵引复位外伤挫入年轻恒牙的临床疗效观察

目的研究微创正畸牵引复位无自发萌出能力的外伤挫入年轻恒牙的临床疗效。 方法选择年轻恒牙外伤挫入的患者8例,年龄7~ 11岁,共11颗上颌切牙,其中9颗重度挫入、2颗中度挫入。观察1个月以上,确定无自发萌出能力后,采用如下微创正畸牵引方式复位：（1）"2 × 4"镍钛弓丝技术：单颗牙中度挫入,邻牙萌出3/4以上;（2）活动基托牵引：重度根向挫入、邻牙萌出不足1/2或伴脱位性损伤;（3）活动基托牵引联合"2 × 4"镍钛弓丝技术：重度唇向或腭向挫入,邻牙萌出不足1/2或伴脱位性损伤。观察治疗后患牙萌出状况、牙根吸收、边缘骨缺损和（或）牙髓变化情况。 结果（1）患牙萌出状况：所有挫入牙均复位;（2）牙根吸收情况：4颗牙出现轻微根吸收,2颗牙牵引前出现根尖部和根中段侧方低密度影,治疗完成时低密度影消退,余牙均无牙根吸收;（3）边缘骨缺损情况：除2颗牙外均无边缘骨缺损;（4）牙髓活力状况：3颗牙齿发育Nolla 10期的挫入牙,牵引前即行牙髓摘除术,4颗牵引中行牙髓摘除术,4颗牙髓活力正常,其中1颗根管钙化。 结论无萌出潜力的挫入年轻恒牙可根据其挫入方向及邻牙萌出程度和受伤情况,分别选择"2 × 4"镍钛弓丝技术、活动基托牵引技术或活动基托联合"2 × 4"镍钛弓丝牵引技术,及时进行微创牵引,可有效复位挫入牙,避免牙根吸收,减少边缘骨缺损,并可能保存活髓,值得进一步推广。     

Maxillary molar intrusion using mini-implants in the anterior palate – “Mousetrap” versus “Mini-Mousetrap”

Supra-erupted maxillary molar teeth pose a major restorative challenge when attempting to prosthetically rehabilitate a partially edentulous mandibular dental arch. Traditional approaches with conventional tooth-borne appliances usually entail undesirable side-effects, including extrusion of adjacent teeth. Temporary anchorage devices (TADs), often inserted in the alveolar process, should help to minimize this phenomenon. The interradicular placement of mini-implants positioned between the roots of the maxillary molars has a number of inherent disadvantages and limitations. The preferred site for insertion of mini-implants is the anterior palate, which ensures a low risk of failure and mini-implant fracture. The ‘Mousetrap’ appliance is comprised of two mini-implants in the anterior palate, with attached lever arms for molar intrusion and a transpalatal arch (TPA) to avoid unwanted palatal tipping of the molar to be intruded. The ‘Mini-Mousetrap’ appliance was designed as a pared-down version without a TPA. If a TPA is not used, molar movement must be closely monitored, and the line of force action may need modification in order to minimize unwanted molar tipping.     

Biomechanics of deep overbite correction

Correction of deep overbite can be accomplished in different ways depending on the treatment goals chosen for individual patients. The 2 primary methods of correction are intrusion of anterior teeth or extrusion of posterior teeth. Successful intrusion of the incisors depends on careful control of the force system used. Low force magnitude, force constancy, a properly selected single point of force application, and control of force direction are all important factors to consider. The design of the intrusion arch may be continuous, or a 3-piece intrusion arch may be selected depending on the needs of the patient. Alternatively, extrusion of posterior teeth may be indicated in patients who are still actively growing and who have short vertical facial dimensions.     

The treatment of severe 'gummy' Class II division 1 malocclusion using the maxillary intrusion splint.

This paper describes a modified Maxillary Intrusion Splint (M.I.S.) system which incorporates a near vertical pull headgear, and its use in the management of severe 'gummy' Class II division 1 malocclusion. The appliance was designed to reduce the visibility and vulnerability of the maxillary incisors in this difficult clinical situation by achieving the intrusion of maxillary teeth, restraining maxillary growth, and encouraging an element of subsequent forward mandibular rotation. The authors' initial experience using this system is presented in a retrospective cephalometric analysis of the lateral skull films of 26 treated patients contrasted with a similar number of comparable controls. The results showed that the principal effects of the M.I.S. were on the maxillary teeth giving decisive overjet control and incisor retraction with actual maxillary incisor intrusion. There was a similar effect on the maxillary molar and the M.I.S. provided effective en masse vertical control of the maxillary dentition. There was some degree of maxillary restraint in the M.I.S. group, but no noticeable difference in the change of mandibular position between the groups at the end of treatment. The possible reasons for this are discussed and suggestions made to improve this aspect of treatment in these patients.     

Spider Screw: skeletal anchorage system

The stability of the anchorage unit plays a very important role in orthodontic control. Controlled orthodontic movements such as retraction and/or protraction of teeth and intrusion of overerupted teeth are very difficult to achieve without patient cooperation and without causing undesirable reciprocal movement in the anchorage unit. The article describes characteristics, surgical procedure, and clinical use of the Spider Screw as an ideal non-dental and non-cooperation based anchorage system. The Spider Screws are self-tapping, titanium mini-screws with immediate loading capability. Their utilization involves a simple biomechanical principle combined with the utilization of minimum orthodontic mechanotherapy. Ideal orthodontic forces (in the range from 50 to 250 gr) can be applied to achieve the desired orthodontic movements. Complete osteointegration is neither expected nor desired with this anchorage system. The Spider Screw anchorage system can be used to support a variety of orthodontic movements specifically in clinical situations involving incomplete dental arches and limited cooperation as in many adult orthodontic cases. The ease of surgical placement combined with the reduced dimension of the Spider Screw diameter equally permits its use in clinical situations where anchorage recovery is necessary during treatment of complete dentitions in classical orthodontic therapy.     

压低磨牙的可摘矫治器制作和临床疗效观察

目的：评估可摘矫治器压低伸长的磨牙的可行性和临床应用价值。方法：选择7例患者,随机采用可摘牙合板式矫治器和真空压膜式矫治器压低伸长的磨牙。治疗前后通过牙颌模型分析评价临床效果。结果：7例患者经过平均3.7个月的治疗均取得比较明显的治疗效果。治疗前后模型分析显示最大压入量为3.05 mm,最小为1.03 mm,月平均压入量为0.58 mm。结论：可摘矫治器用于压低伸长的磨牙有明显的临床效果。可摘矫治器具有美观、便于口腔卫生维护、制作简便、成本低廉的特点。     

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目的探讨应用微种植体支抗治疗安氏Ⅱ类1分类错畸形临床疗效及治疗方法临床要点。方法对2005—2008年在山东省济宁口腔医院就诊的安氏Ⅱ类1分类上颌前突或伴轻微下颌后缩的正畸患者11例,采用MBT(滑动)直丝弓矫治技术,进行减数双尖牙矫治。黏结矫治器之前在上颌双侧第二双尖牙和第一磨牙之间的颊侧分别植入微种植体,在治疗早期应用自攻型微种植体进行尖牙向远中牵引,并在更换至稳定弓丝后利用微种植体整体内收前牙,牵引力值为1.5～2.0N,平均治疗时间为19个月,治疗结束观察1年。于治疗前后拍摄头颅侧位片,进行头影测量分析。结果11例患者除1例种植体松动脱落,其余患者第一磨牙在前后向和垂直向均未发生显著性移动,患者的颜面侧貌得到明显改善,取得较为满意的治疗效果。与治疗前相比,治疗后SNA、ANB、FHtoU1、IMPA角明显减小,差异均具有统计学意义;SNB角略有增大,FMA略有减小,但差异无统计学意义。结论微种植体支抗能够有效治疗安氏Ⅱ类1分类患者,并达到磨牙强支抗的效果。     

A clinical assessment of the Active Vertical Corrector--a nonsurgical alternative for skeletal open bite treatment

This article describes the Active Vertical Corrector (AVC), which is a simple removable or fixed orthodontic appliance that intrudes the posterior teeth in both the maxilla and mandible by reciprocal forces. By the use of effective posterior intrusion of teeth, the mandible is allowed to rotate in upward and forward directions. The uniqueness of this appliance is that it allows the clinician to correct anterior open bite problems by actually reducing anterior facial height. This treatment approaches the problem at its cause (overeruption of posterior teeth) and provides better facial balance and esthetics than most conventional orthodontic treatment procedures. Problems formerly thought to require orthognathic surgery can now be treated successfully with the AVC.     

Using a Motion‐Capture System to Record Dynamic Articulation for Application in CAD/CAM Software

Purpose: One of the current limitations of computer software programs for the virtual articulation of the opposing teeth is the static nature of the intercuspal position. Currently, software programs cannot identify eccentric occlusal contacts during masticatory cyclic movements of the mandible. Materials and Methods: Chewing trajectories with six degrees of freedom (DOF) were recorded and imposed on a computer model of one subject's maxillary and mandibular teeth. The computer model was generated from a set of high‐resolution μ‐CT images. To obtain natural chewing trajectories with six DOF, an optoelectronic motion‐capturing system (VICON MX) was used. For this purpose, a special mandibular motion‐tracking appliance was developed for this subject. Results: Mandibular movements while chewing elastic and plastic food samples were recorded and reproduced with the computer model. Examples of mandibular movements at intraoral points are presented for elastic and plastic food samples. The potential of such a kinematic computer model to analyze the dynamic nature of an occlusion was demonstrated by investigating the interaction of the second molars and the direction of the biting force during a chewing cycle. Conclusions: The article described a methodology that measured mandibular movements during mastication for one subject. This produced kinematic input to 3D computer modeling for the production of a virtual dynamic articulation that is suitable for incorporation into dental CAD/CAM software.     

三种快速扩弓联合前方牵引装置作用效果的三维有限元分析

目的　应用三维有限元法比较三种快速扩弓联合前方牵引装置对颌骨及牙齿的作用效果,为临床治疗提供参考。方法　建立Hyrax联合牙性前方牵引装置、骨支持式扩弓器（maxillary skeletal expander,MSE）联合牙性前方牵引装置、MSE联合骨性前方牵引装置及颅上颌复合体的三维有限元模型,对扩弓螺旋器施加0.25 mm的横向位移并于装置牵引位点施加大小为500 g/侧的牵引力,力的方向与咬合平面呈30°向下,分析三种快速扩弓联合前方牵引装置作用下的颌骨及牙齿的位移趋势及应力分布。结果　三种装置作用下的颌骨应力分布及位移趋势相似,但两种MSE联合前方牵引装置作用下的颌骨横向位移量为Hyrax联合前方牵引装置位移量的2.7倍,矢状向的位移量为Hyrax联合前方牵引装置的2.6倍,颌骨的应力值远大于Hyrax联合前方牵引装置;三个模型的牙齿位移趋势相似,但牙齿应力分布模式不同,MSE联合骨性前方牵引装置对于磨牙仍有作用力。结论　①对于需要大的颌骨移动量及错过生长发育的患者可选择骨性快速扩弓前方牵引装置。②MSE联合前方牵引装置仍需改进。     

The 'ballista spring" system for impacted teeth.

The ballista spring system is a simplified orthodontic system for treating impacted teeth. The impacted tooth is retracted by a spring that accumulates a continuous force from being twisted on its long axis. The necessary operation on the impacted tooth is simple and less traumatic. The force exerted on the tooth is vertical, without compressing the impacted tooth toward the adjacent roots. This force is well controlled and easily modified. By the lack of appliance on the front teeth during a great part of the treatment, the esthetic side of the treatment is respected. Complicated impacted teeth in adults can be treated.