Update of the classification of midpalatal suture behaviour after surgically assisted rapid maxillary expansion using computed tomography

The aim of this study was to update the midpalatal suture classification after surgically assisted rapid maxillary expansion (SARME) using computed tomography (CT). Thirty-five patients with a transverse maxillary deficiency and unilateral or bilateral posterior crossbite underwent SARME with osteotomy of the pterygoid apophysis of the sphenoid. CT was performed before installation of the Hyrax expander appliance and after the final activation. Opening of the midpalatal suture was classified into three types: type I, total midpalatal suture opening from anterior nasal spine (ANS) to posterior nasal spine (PNS); type II, partial midpalatal suture opening from ANS to the transverse palatine suture, with partial or non-existent opening of the midpalatal suture posterior to the transverse palatine suture; type III, complete maxillary opening from ANS, but not of PNS, because a paramedian fracture completed the opening of the hard palate. Type I was observed in 42.8% of the patients, type II in 40%, and type III in 17.2%. Opening of the transverse palatine suture was found in all midpalatal suture opening patterns and was more frequent in type III, followed by type II and type I. CT was used to update the classification of midpalatal suture patterns, with the inclusion of type III: total opening of the hard palate due partly to opening of the midpalatal suture and partly to a paramedian fracture.     

Surgically assisted rapid maxillary expansion by opening the midpalatal suture

The results of surgically assisted rapid maxillary expansion by opening of the midpalatal suture in 25 patients are reported. Osteotomy of the lateral wall of the maxilla combined with pterygomaxillary dysjunction and midpalatal suture separation allowed for successful rapid maxillary expansion in 23 patients. The two patients who did not respond to treatment were found to have unusually thick midpalatal sutures, which were successfully expanded after the midpalatal sutures were osteotomized.     

Three-dimensional finite-element analysis of maxillary protraction with and without rapid palatal expansion

The aims of this study were to determine the reaction of the craniofacial bones on the protraction force transferred to the maxillary body, and whether or not the midpalatal suture had opened during skeletal Class III treatment. A computerized tomograph was obtained from a dry skull with a normal occlusion to construct a three-dimensional finite-element model (3D.FEM) of the craniofacial bones and the maxillary teeth to simulate actual bone reactions. A protraction force of 500 g was applied at the first premolar region, directed 20 degrees inferior to the occlusal plane. The displacement and the stress distribution of the craniofacial bones and sutures were then calculated using the ANSYS 5.3 program dividing the analysis into two simulations, based on whether or not the midpalatal suture was opened. The results showed that there was less compressive stress and greater tensile stress in the circumaxillary suture areas when the midpalatal suture was opened. The amount of displacement and deformation when the midpalatal suture was opened also demonstrated a decrease in upward-forward rotation of the maxilla and zygomatic arch and greater amounts of displacement in the frontal, vertical, and lateral directions compared with no opening of the midpalatal suture. Analysis of these results showed that maxillary protraction produce similar changes to normal downward and forward growth of the maxilla and was achieved with accompanying opening of the midpalatal suture.     

Transverse effects after surgically assisted rapid maxillary expansion in the midpalatal suture using computed tomography

Surgically assisted rapid maxillary expansion is the treatment of choice for correcting maxillary transverse deficiency in adults. Traditionally, the appliance for expansion is tooth-borne and tissue-tooth-borne devices (Hyrax and Haas). Although a number clinical and radiographic studies have evaluated the surgically assisted rapid maxillary expansion, only limited information is available to study the transverse movement of the midpalatal suture with computed tomography. Forty adult patients of both sexes, ranging in age from 18 to 38 years, with bilateral transverse maxillary deficiency were operated on. Twenty patients had Hyrax expander, and 20 had Haas expander. Under general anesthesia, subtotal Le Fort I osteotomy was performed including pterygomaxillary dysjunction. The width of the midpalatal suture opening was measured at the anterior edge of the midpalatal suture and at the junction of the midpalatal suture and palatal bones, using computed tomography in axial acquisition, obtained in the preoperative period and immediately after the end of expansion. A digital caliper was used to measure Haas and Hyrax distance on the central jackscrew preoperatively and postoperatively. The proportion between the midpalatal suture expansion and the amount of expansion on the jackscrew was evaluated. The mean of midpalatal suture opening and screw opening for Haas group was 5.19 and 8.78 mm, and for the Hyrax group, 5.85 and 8.51 mm, respectively. Both groups showed parallel-shaped separation of the midpalatal opening with no significant difference in the anterior and posterior portion. Midpalatal/jackscrews opening proportion was greater in the Hyrax group (69,2%) than in the Haas group (60%).     

Strategies for surgically assisted rapid maxillary expansion according to the region of transverse maxillary deficiency

This study evaluated different techniques for surgically assisted rapid maxillary expansion (SARME) according to the type of transverse maxillary deficiency using computed tomography (CT). Six adult patients with bilateral transverse maxillary deficiencies underwent SARME. The patients were equally divided into three groups: Group I, maxillary atresia in both the anterior and posterior regions; Group II, greater maxillary atresia in the anterior region; and Group III, increased maxillary atresia in the posterior region. In Group I, a subtotal Le Fort I osteotomy was used. In Group II, a subtotal Le Fort I osteotomy was used without pterygomaxillary suture disjunction. In Group III, a subtotal Le Fort I osteotomy was used with pterygomaxillary suture disjunction and fixation of the anterior nasal spine with steel wire. The midpalatal suture opening was evaluated preoperatively and immediately after the activation period using CT. For Group I, the opening occurred parallel to midpalatal suture; for Group II, the opening comprised a V-shape with a vertex on the posterior nasal spine; and for Group III, the opening comprised a V-shape with a vertex at the anterior nasal spine. The conclusion was that the SARME technique should be individualized according to the type of transverse maxillary deficiency.     

Surgical and orthodontic rapid palatal expansion in adults using Glassman's technique: retrospective study

In 1984, Glassman et al. described a conservative surgical method of separation of the midpalatal suture in which an osteotomy is done only at the lateral and anterior wall of the maxilla. Between 1991 and 1997, we have operated on 21 patients with maxillary transverse discrepancies using the method that they described. This gave good results in 20 patients. The other, who was operated on at the age of 38 years, developed a fracture of the alveolar process of the maxilla on one side because of ossification of the midpalatal suture. The surgically assisted rapid palatal expansion described by Glassman et al. is suitable for patients up to the age of 30. Older patients require additional surgical separation of the midpalatal suture.     

Rapid palatal expansion in the young adult: time for a paradigm shift?

A 19-year-old man presented for correction of a malocclusion that included a transverse maxillary deficiency. The patient was informed that he required orthognathic surgery to expand his upper jaw and correct his malocclusion, but he refused surgical expansion. Recent evidence indicates that rapid palatal expansion can be used without surgery in young adults; the decision was therefore made to treat the patient nonsurgically. Rapid palatal expansion of the maxillary arch was accomplished by means of a Hyrax appliance, with post-treatment radiographs revealing an opening of the midpalatal suture. The belief still persists among some clinicians that young adult patients require orthognathic surgery for palatal expansion, despite recent evidence supporting a nonsurgical approach after closure of the midpalatal suture.     

扩张力作用下大鼠腭中缝组织成骨现象的连续观察

目的：观察扩张力作用下大鼠腭中缝牵张成骨的组织形态学变化及新骨形成情况,探讨扩弓后腭中缝组织的反应和新骨形成方式。方法：选用4周龄健康雄性wistar大鼠55只,随机分为实验组5组、对照组6组,采用两眼簧后牙扩弓器扩张大鼠上颌腭中缝组织,分别于0d、实验1、2、4、7、11d取材,标本常规进行石蜡切片,行常规苏木精-伊红染色、Masson三色染色、骨钙素（OCN）免疫组化。结果：扩张1d后即可见腭中缝明显增宽,并可见成骨细胞的分化和成纤维细胞的增殖;扩张2d和4d后可见软骨细胞带外侧有新骨沉积;固定3d后可见骨缝边缘内外侧均有新骨沉积;固定7d后,可见两侧陈旧的软骨细胞带内侧有大量类骨质形成,两侧骨缘呈指状嵌合。结论：扩张的腭中缝新骨改建主要发生在腭中缝骨缘,并由软骨内成骨的方式向膜内成骨方式进行转变。     

用计算机图形分析法评价上颌扩大患者腭中缝的改变

本实验采用计算机图形分析法，对8名经螺旋扩大器扩弓，磁力扩弓治疗的患者咬X线片进行分析，测量其腭中缝面积在治疗前后的改变，结果显示螺旋扩弓患者治疗后腭中缝面积增大0.10421～0.44839cm2．磁力扩弓患者腭中缝面积增大0．09074～0．23594cm2，对腭中缝的改变做到了准确的定性、定量分析，证明是一种评价患者腮中缝改变的良好方法。     

Evaluation of opening pattern and bone neoformation at median palatal suture area in patients submitted to surgically assisted rapid maxillary expansion (SARME) through cone beam computed tomography

Surgically assisted rapid maxillary expansion (SARME) is the treatment of choice to adult patients even with severe transversal maxillary discrepancies. However, the adequate retention period to achieve the bone remodeling, thus assuring treatment stability, is controversial.

Objective

To evaluate the opening pattern and bone neoformation process at the midpalatal suture in patients submitted to surgically assisted (SARME) through cone beam computed tomography (CBCT).

Material and Methods

Fourteen patients were submitted to SARME through subtotal Le Fort I osteotomy. Both the opening pattern and the mean bone density at midpalatal suture area to evaluate bone formation were assessed pre- and post-operatively (15, 60 and 180 days) through CBCT.

Results

Type I opening pattern (from anterior to posterior nasal spine) occurred in 12 subjects while type II opening pattern (from anterior nasal spine to transverse palatine suture) occurred in 2 individuals. The 180-day postoperative mean (PO 180) of bone density value was 49.9% of the preoperative mean (Pre) value.

Conclusions

The opening pattern of midpalatal suture is more related to patients’ age (23.9 years in type I and 33.5 years in type II) and surgical technique. It was not possible to observe complete bone formation at midpalatal suture area at the ending of the retention period studied (180 days).     

上颌快速扩弓腭中缝血管内皮生长因子的时空表达与新骨形成的相关性研究

目的 探讨上颌快速扩弓扩张期和固定期兔腭中缝组织血管内皮生长因子（VEGF）的时空表达模式以及新骨形成情况。方法 将44只新西兰大白兔随机分为11组：实验组（共5组）、对照组（共5组）、对照0组,每组4只。用螺旋分裂基托扩大矫治器（Haas矫正器）扩张兔上牙弓,快速扩张2周,固定4周。在安装扩张器当天（对照0组）、快速扩张第1、2周、固定第1、2、4周（实验组和对照组）取兔上颌骨腭中缝组织块,采用免疫组织化学法检测VEGF在腭中缝组织中的分布和表达变化,采用过碘酸-Schiff染色法观测新骨形成。结果 快速扩张的腭中缝可见高水平的VEGF表达,VEGF阳性信号主要定位于血管内皮细胞胞浆和增殖活跃的成骨细胞胞浆。对照组VEGF在整个实验过程中均呈弱阳性表达。实验组快速扩张第1周、快速扩张第2周、固定第1周、固定第2周VEGF蛋白表达量均高于对照组。随着机械应力快速扩张,实验组VEGF蛋白表达量逐渐上升,固定1周达峰值后逐渐下降。实验组新骨形成的量均高于对照组,新骨形成的量逐渐上升,固定2周达峰值后逐渐下降。结论 上颌快速扩弓产生的机械牵张力可以导致VEGF生成增加从而促进血管及新骨的生成。     

MSE骨性扩弓对成人上牙弓狭窄扩弓效果的CBCT分析

目的 观察分析MSE骨性扩弓治疗成人上牙弓狭窄的扩弓效果.方法 选取上牙弓狭窄的成人患者13例(18～24岁;平均年龄20.7岁,男6例,女7例),应用MSE骨性扩弓器进行上牙弓扩宽;所有患者均在3个月内完成加力.扩弓后拍摄CBCT与扩弓前CBCT对比,分析扩弓前后上牙弓及颌骨横向宽度相关指标的变化.数据比较采用配对t...     

Evaluation of craniofacial effects during rapid maxillary expansion through combined in vivo/in vitro and finite element studies

It is well documented in the literature that a contracted maxilla is commonly associated with nasal obstruction. Midpalatal splitting using the rapid maxillary expansion (RME) technique produces separation of the maxillary halves with consequent widening of the nasal cavity. Although clinicians agree about many of the indications for and outcomes of RME, some disagreements persist in relation to the biomechanical effects induced. The present research was based on the parametric analysis of a finite element model (FEM) of a dry human skull with the RME appliance cemented in place in order to evaluate these effects on the overall craniofacial complex with different suture ossification. The behaviour of the FEM was compared with the findings of a clinical study and to an in vitro experiment of the same dry skull. Comparisons refer to the opening pattern and associated displacements of four anatomical points located at the left and right maxilla (MI, UM, EM, CN). It was found that the maxillolacrymal, the frontomaxillary, the nasomaxillary, the transverse midpalatal sutures, and the suture between the maxilla and pterygoid process of the sphenoid bone did not influence the outcome of RME, while the zygomatico-maxillary suture influenced the response of the craniofacial complex to the expansion forces. Moreover, the sagittal suture at the level of the frontal part of the midpalatal suture plays an important role in the degree and manner of maxillary separation. Maximum displacements were observed in the area of maxilla below the hard palate, from the central incisors to second premolars, which dissipated at the frontal and parietal bone and nullified at the occipital bone.     

机械扩张力作用下小鼠腭中缝EphB4和ephrinB2表达的研究

目的　观察小鼠腭中缝在机械扩张力作用的不同阶段EphB4/ephrinB2分布和表达规律。方法　选用6周龄健康雄性C57BL/6小鼠40只,随机分成对照组和实验扩张组,每组各20只。用双眼簧扩弓器施加扩张力（0.56 N）于实验加力组小鼠的腭中缝区。实验组分别于加力后1、3、7、14 d抽取5只小鼠通过石蜡切片免疫组化对EphB4/ephrinB2进行组织定位,观察表达规律并与未施力的对照组比较。结果　扩张组EphB4/ephrinB2表达水平高于对照组,差异具有统计学意义。第3天实验组EphB4/ephrinB2表达水平表达最高。结论　对小鼠腭中缝施加扩张力的情况下能够诱导EphB4/ephrinB2的表达增加,说明EphB4/ephrinB2在腭中缝扩张新骨改建过程中具有重要意义。     

机械张应力对兔腭中缝血管内皮生长因子mRNA表达的影响

目的　观察在快速扩张兔腭中缝的扩张期和固定期血管内皮因子 (VEGF)mRNA表达情况。方法　用螺旋分裂基托扩大矫治器 (Haas矫正器 )扩张兔上牙弓 ,每 12h 0 .2 5mm ,共扩张牵引 14d ,分别于即刻 ,第 1、2、3、4、6周取材 ,标本常规进行逆转录聚合酶链反应 (RT -PCR)检测VEGFmRNA的表达。结果　第 1、2、3、4、6周VEGFmRNA表达量实验组均高于对照组。在实验组VEGFmRNA各组间的变化趋势为随着机械应力快速扩张 ,VEGFmRNA的表达量逐渐上升 ,固定 1周达峰值 ,以后逐渐下降 ,到固定 4周表达水平接近正常。结论　机械牵张力刺激可以导致内源性VEGF生成 ,VEGF可能在缝牵引成骨过程中血管生成及随后的新骨生成过程中扮演重要的角色     

Nonsurgical rapid maxillary expansion effects on craniofacial structures in young adult females. A bone scintigraphy study

OBJECTIVE: To evaluate the skeletal effects of nonsurgical rapid maxillary expansion (RME) on craniofacial structures with bone scintigraphy in young adult female subjects. MATERIALS AND METHODS: The material of the present study consists of scintigraphic records taken from 17 early adult females treated with RME. All patients had a bilateral posterior crossbite, transverse maxillary deficiency, deep palatal vault, and dental crowding at the beginning of the treatment. The age range of the patients was 16.1 to 18.8 years, and the mean age was 17.3 +/- 0.86 years. Bone scintigraphy records were obtained before RME (T1), during the splitting of the midpalatal suture (T2), and after the end of active widening period (T3). Repeated measure analysis of variance was used to assess the differences between the periods. In addition, Bonferroni multiple comparison tests were applied to the measurements at which F values were found to be statistically significant. RESULTS: According to the statistical analysis, significant activity changes were found in all regions studied and in all slices. The metabolic activity in all regions showed significant increases up to the separation of the midpalatal suture (T1-T2), whereas the metabolic activity exhibited a remarkable decrease (T2-T3) after the opening of the midpalatal suture. CONCLUSIONS: Scintigraphic records revealed an increase in the regions of interest scores during RME in all regions and all slices. Therefore, it can be speculated that RME has had not only dental effects but also skeletal effects on young adult patients.     

槲皮素在大鼠上颌快速扩弓时对腭中缝骨改建的影响

目的：研究槲皮素对大鼠上颌快速扩弓时腭中缝骨质改建的作用。方法：18只6周龄SPF级雄性Wistar大鼠,随机分为3组,A组为空白对照组,B组为扩弓组,C组为扩弓并灌服槲皮素组,每组均6只。其中,A组不扩弓,也不灌服槲皮素;B﹑C组用双眼圈簧扩弓器扩弓,力值0.98 N,C组扩弓后每天灌服槲皮素（100 mg/kg）,A、B组根据体重灌服同剂量的生理盐水。14 d后处死大鼠,标本进行石蜡切片,行常规苏木精-伊红染色、Masson三色染色、免疫组织化学染色。利用Image-pro plus软件对切片吸光度进行分析,采用SPSS 19.0 软件包对数据进行统计学分析。结果：实验第14天,H-E染色和Masson染色显示,A组腭中缝见少量纤维组织,可见软骨细胞、间充质样细胞及成骨细胞等;B﹑C组腭中缝处纤维组织较多,成纤维细胞﹑软骨细胞增多,腭中缝近骨区域处多见成骨细胞;C组成骨细胞数量明显多于B组,有新骨钙化沉积。免疫组织化学染色显示,B组大鼠腭中缝组织中的BMP-2表达量在第14天时显著高于A组（P<0.01）,C 组大鼠腭中缝组织中BMP-2 的表达量显著高于B组（P<0.05）。结论：上颌快速扩弓可扩大生长发育期大鼠的腭中缝;槲皮素能够促进大鼠上颌快速扩弓时腭中缝BMP-2的表达,使骨质沉积钙化,加速新骨形成。     

上颌快速扩大兔腭中缝组织改建的连续组织学研究

目的研究上颌快速扩大腭中缝牵张成骨的连续过程及规律，了解快速扩张腭中缝的缝组织反应和组织再生机理。方法选用处于生长期新西兰大白兔52只，随机分为13组，实验组5组、对照组6组，荧光标记的实验组和对照组各1组。采用螺旋分裂基托扩大矫治器（Haas矫正器）扩张兔上牙弓，快速扩张期2周，固定期4周。扩张速率为0．25mm／12h，共扩张牵引14天，分别于即刻、第7、14、21、28、42天取材，标本常规进行组织学观察。并利用激光共聚焦扫描显微镜及荧光标记观察快速扩张腭中缝成骨活动的情况。结果快速扩张2周后可见腭中缝明显增宽，可见创伤性反应，成骨和成纤维细胞大量增殖，大量胶原纤维沿扩张力方向有序排列，成骨活动沿骨缝边缘平行沉积。快速扩张的腭中缝有强烈的血管生成反应，新生骨组织改建活跃，直至新的骨缘形成。缝恢复正常的形态。荧光标记观察实验组骨沉积带明显宽于对照组。结论扩张的腭中缝新骨改建主要发生在腭中缝骨缘。腭中缝改建的过程是纤维修复和骨组织再生过程。     

Bone marrow mesenchymal stem cells enhance bone formation in orthodontically expanded maxillae in rats

Objective:To transplant bone marrow–derived mesenchymal stem cells (MSCs) into the interpremaxillary suture after rapid maxillary expansion with the aim of increasing new bone formation in the suture.Materials and Methods:Nineteen male Wistar rats were divided into two groups (control, n  =  9; experimental, n  =  10). Both groups were subjected to expansion for 5 days, and 50 cN of force was applied to the maxillary incisors with a helical spring. Pkh67⁺ (green fluorescent dye)–labeled MSCs were applied to the interpremaxillary suture after force application into the interpremaxillary suture of rats. Bone formation in the sutural area was histomorphometrically evaluated, including the amount of new bone formation (µm²), number of osteoblasts, number of osteoclasts, and number of vessels. Mann-Whitney U-test was used for statistical evaluation at the P < .05 level.Results:After 10 days of retention, Pkh67⁺ can be detected in suture mostly in the injection site under fluorescence microscope. Histomorphometric analysis revealed that a single local injection of MSCs into the midpalatal suture increased the new bone formation in the suture by increasing the number of osteoblasts and new vessel formation, compared with controls injected with phosphate-buffered saline.Conclusions:This preclinical study might provide foundations for the underlying potential clinical use of MSCs after maxillary expansion. Given the fact that MSCs are currently in use in clinical trials, this approach might be a feasible treatment strategy to accelerate new bone tissue formation in midpalatal suture and to shorten the treatment period for patients undergoing maxillary expansion reinforcement     

Unusual intraosseous transmigration of a palatally impacted canine.

Intraosseous migration of impacted teeth across the midline to the opposite side of the jaw is a rare dental anomaly of unknown etiology. Transmigration of an impacted mandibular canine through the symphysis to the contralateral side of the arch has been documented. Transmigration of an impacted maxillary canine across the midpalatal suture to the opposite side of the maxilla has not been previously observed and is reported here for the first time.