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.     

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.     

Evaluation of the midpalatal suture during rapid palatal expansion in children: a CT study

The midpalatal suture of 18 children submitted to rapid palatal expansion with the Haas fixed expander and ranging in age from 5 years 2 months to 10 years 5 months was evaluated with computerized tomography. The posterior nasal spine undergoes the impact of RPE in patients in the primary and mixed dentition stages, similarly to the anterior nasal spine though to a lesser extent. The average opening of the midpalatal suture was 2.21 mm in the anterior nasal spine region and 0.95 mm in the posterior nasal spine region.     

Comparison of skeletal maxillary transverse deficiency treated by microimplant-assisted rapid palatal expansion and tooth-borne expansion during the post-pubertal growth spurt stage:: A prospective cone beam computed tomography study

ObjectiveTo investigate the efficacy of microimplant-assisted rapid palatal expansion (MARPE) to treat skeletal maxillary discrepancies during the post-pubertal growth spurt stage.Materials and MethodsSixty patients with skeletal maxillary transverse deficiency during the post-pubertal growth spurt stage were randomly divided into MARPE and Hyrax groups. Thirty patients (mean age: 15.1 ± 1.6 years) were treated using the four-point MARPE appliance; 30 patients (mean age, 14.8 ± 1.5 years) were treated using the Hyrax expander. Cone beam computed tomography scans and dental casts were obtained before and after expansion. The data were analyzed using paired t-tests and independent t-tests.ResultsThe success rates of midpalatal suture separation were 100% and 86.7% for MARPE and Hyrax groups, respectively. Palatal expansion and skeletal to dental ratio at the first molar level were greater in the MARPE group (3.82 mm and 61.4%, respectively) than in the Hyrax group (2.20 mm and 32.3%, respectively) (P < .01). Reductions in buccal alveolar bone height and buccal tipping of the first molars were less in the MARPE group than in the Hyrax group (P < .01).ConclusionsMARPE enabled more predictable and greater skeletal expansion, as well as less buccal tipping and alveolar height loss on anchorage teeth. Thus, MARPE is a better alternative for patients with skeletal maxillary deficiency during the post-pubertal growth spurt stage.     

Sagittal and vertical maxillary effects after surgically assisted rapid maxillary expansion (SARME) using Haas and Hyrax expanders

The purpose of this study was to evaluate the effect of surgically assisted rapid maxillary expansion on the sagittal and vertical maxillary planes. Thirty-three adult patients aged between 18 and 40 years who required surgically assisted rapid maxillary expansion were included in this study. They were divided into two groups: the Haas type expander (16) and the Hyrax type expander (17). All patients were subjected to subtotal LeFort I osteotomy with pterygomaxillary disjunction. Lateral cephalometric radiographs were taken during the preoperative assessment (T1), soon after completion of the expansion (T2), and 4 months after the end of the expansion (T3). The following cephalometric measures were obtained in each of the three radiographs for all the patients: SNA, SN palatal plane, Frankfurt horizontal plane. NA, CF-A, CF-NA, Nperp-A, CF-A, Frankfurt horizontal plane-ANS, and Frankfurt horizontal plane-PNS. Statistically significant changes were observed in the cephalometric measures: SNA, Frankfurt horizontal plane, NA, Nperp-A in the patients in the Haas group, and CF-A in the patients in the Hyrax group, demonstrating anterior displacement of the maxilla. The cephalometric measures SN.palatal plane, CF-A, CF-NA, Frankfurt horizontal plane-ANS, and Frankfurt-PNS plane that evaluated vertical displacement did not show changes in either group. The surgically assisted rapid maxillary expansion caused anterior displacement of the maxilla in both groups, but only the Haas group had statistical significance. Neither the Haas group nor the Hyrax group showed vertical displacement of the maxilla. When Hyrax and Haas groups were compared, there were no statistically significant differences for sagittal and vertical changes.     

Transverse effects of surgically assisted rapid maxillary expansion: a comparative study using Haas and Hyrax

BACKGROUND: Surgically assisted rapid maxillary expansion is the treatment of choice for correcting transverse maxillary deficiency in patients with skeletal maturity, although the influence of the expander type on these alterations has not been elucidated yet. OBJECTIVE: Determine the skeletal and dental transverse effects on the maxilla after completion of surgically assisted rapid maxillary expansion, with Haas and Hyrax expanders. METHODS: Thirty-eight patients (aged between 18 and 39 years) were submitted to subtotal Le Fort I osteotomy and divided into Hass and Hyrax groups (19 patients each). Measurements of maxillary width, upper intermolar width, and its inclination on the posteroanterior cephalometric radiographs were obtained in the preoperatory period (T1), after the completion of the expansion (T2), and 4 months after the completion of the expansion (T3). The intercusp and intergingival distances measured on the plaster models were obtained from the first premolars and molars, before expander cementation (M1) and after the expander removal (M2). RESULTS: Both groups revealed statistically significant increase in the maxillary width, upper intermolar width, and inclination of the molars in T2 (P<0.001); T3 showed a statistically significant decrease in the maxillary width and inclination of the molars (P<0.001). The expansion presented an increment on the maxillary width of 71% from the upper intermolar width (T1-T3), and molars had vestibular inclination (P<0.05). The ratio of width increase of maxilla by the amount of device activation was of 69% for Haas and 74.5% for Hyrax. CONCLUSION: Clinically, the transversal effects were similar for both groups.     

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.     

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).     

种植钉辅助上颌快速扩弓治疗年轻成人上颌牙弓狭窄的CBCT分析

目的 探讨种植钉辅助上颌快速扩弓治疗年轻成人上颌狭窄的效果.方法 样本包括15.5～28.0岁上颌骨性狭窄病例10例(男3例,女7例),平均年龄(20.1±5.4)岁.使用种植钉辅助上颌快速扩弓技术,分别于治疗前、扩弓后和保持3个月后拍摄CBCT,并对资料进行统计分析.结果 扩弓后腭中缝前部和后部分别增加3.49 mm和2.94 mm,后部腭中缝增量占扩弓器扩大量的47.9％,后部腭中缝增量占第一磨牙间宽度增量的52.3％.鼻腔宽度、上颌基骨和牙槽宽度扩弓后增加(P＜0.05),且保持三个月后增加量无明显改变.牙槽骨高度变化无统计学意义(P＞0.05).结论 种植钉辅助上颌快速扩弓能有效开展年轻成人腭中缝,矫正骨性牙弓狭窄,并减少牙支抗扩弓引起的副作用.     

改良式Hyrax扩弓器矫治上颌牙弓狭窄的临床观察

目的观察改良式Hyrax扩弓器对生长发育期上颌牙弓狭窄的矫治作用。方法选择14例恒牙早期上颌牙弓狭窄病例,应用改良式Hyrax扩弓器进行扩弓。通过测量扩弓前后X线头颅定位侧位片和模型,进行统计学分析。结果14例上颌牙弓狭窄患者经2~3周扩弓后,后牙反全部解除并过矫治2~3mm,■间出现间隙2~4mm。上颌正中咬合片显示:腭中缝打开,低密度阴影出现。结论改良式Hyrax扩弓器是一种快速、有效、安全、经济实惠的扩弓装置。     

Orthodontic and orthopedic expansion of the transverse dimension: A four decade perspective

This paper describes four decades of research carried out at the University of Michigan that has investigated the clinical alteration of the transverse dimension of the face, with specific attention given to orthodontic and orthopedic treatment of patients in the early mixed dentition. The results of a series of clinical studies beginning in the late 1970s are described that consider the etiology of dental crowding as well as treatment effects produced by expansion in the late mixed/early permanent dentition and the early mixed dentition. A treatment protocol for early treatment is described that includes the lower Schwarz appliance, a bonded acrylic splint expander and the placement of anterior brackets. A series of retrospective and prospective studies are presented, including a study investigating the spontaneous improvement of Class II malocclusion following increases in the transverse dimension. The effect of maintaining or increasing anterior arch length on subsequent mandibular second molar eruption is evaluated. The ideal timing for rapid maxillary expansion is before puberty. An individual assessment of the midpalatal suture using cone-beam computed tomography (CBCT) images can be useful when making a clinical decision between conventional and surgically assisted RME, especially for adolescent and young adult patients.     

Comparison of traditional RPE with two types of micro-implant assisted RPE: CBCT study

Recently, various types of the Micro-implant Assisted RPE (MARPE) were introduced to obtain greater skeletal expansion and to minimize dental effects. In the present study, we evaluated skeletal and dental effects immediately after the completion of expansion using three different types of expanders— a traditional tooth-anchored maxillary expander (TAME) and two different types of MARPE, bone-anchored maxillary expander (BAME) and tooth-bone-anchored expander (MSE) using CBCT in adolescents. Overall, the MSE group showed much greater skeletal changes than the TAME and BAME groups, especially, at the nasal floor, maxillary base, and palatal suture. About 72–78% of suture opening was at PNS, which indicates slightly more opening anteriorly than posteriorly; however, it was relatively parallel in nature than anticipated. In all three groups, the greatest transverse changes with expansion occurred at the molar crowns and the 2nd greatest changes at the palatal suture opening at ANS. It is suggested that MSE can be a great alternative method in correcting maxillary skeletal transverse deficiency.     

Assessment of the relationship between the upper and lower arch changes with the opening of the expanding screw after the rapid maxillary expansion

Objective: The purpose of this study is to assess the relationship of the upper and lower arch dimension changes after the rapid maxillary expansion (RME) with the screw opening of the modified Hyrax type appliance. Materials and methods: Initial (T1) and final (T2) models of study of 63 children between 7 years and 6 months and 16 years and 5 months were performed. From these, 21 showed maxillary atresia and/ or posterior crossbite and were submitted to expansion and 42 children formed the control group .The appliance used in this work was the modified Hyrax appliance using the 7mm expanding screws "Dentarum". The measures of the upper intercanine and the upper and lower intermolar distances were performed in plaster models with the help of a "Digital Paquimeter". The opening of the appliance's screw was also assessed. Results: the RME provoked a statistically significant increase in the upper interdental distances and no statistic significance in the lower interdental distances, i.e. the change in the 16 - 26, 13 - 23 e 36 - 46 distance was of 5,85 mm, 5,31 and 0,34 mm respectively. The average opening of the expander screw, which was of 6,27 mm. Conclusion: the appliance's opening is related to the interdental distance changes, i.e. for each appliance's opening mm, a 0,94 variation in the upper intermolar distance, a 0,87 in the upper intercanine distance and 0,054 in the lower intermolar distance are provoked. KEY WORDS: Rapid maxillary expansion, posterior crossbite, transverse maxillary deficiency, dental arch.     

快速腭扩展对牙颌横向矫治作用的研究

目的：探讨快速腭扩展对牙颌各结构的横向矫正作用。方法：对12例恒牙期上颌狭窄病例用Hyrax扩弓器行快速腭扩展矫治。通过矫治前后研究模型分析,头颅后前位定位X线片头影测量分析评价腭扩展效果。结果：快速腭扩展使上腭中缝打开,上颌牙齿及牙槽基骨颊向移动,支抗磨牙位移最大,平均4.84mm。牙槽突点（alm）侧移大于上颌点（mx）。全鼻高侧移过程中以鼻高中1/2水平（bn50）侧移量最大,平均2.74mm。上颌中线两侧牙齿,牙槽骨及颌骨位移值的变化无统计学差异。结论：上颌快速腭扩展在打开腭中缝解除上牙弓狭窄时,上颌牙齿、牙槽基骨发生了颊向移动,基骨位移量大于牙齿位移量,上颌牙槽突发生了形变。鼻上颌复合体整体位移效果呈三角形,中线两侧基本对称。     

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.     

Upper airway assessment using four different maxillary expanders in cleft patients: A cone-beam computed tomography study

Objective:To evaluate the anterior and posterior maxillary width, the nasal passage volume, the oropharyngeal minimum axial area, and volume changes in unilateral cleft lip and palate patients treated with one of the following four expanders: Hyrax, Fan-Type, inverted mini-hyrax supported on the first permanent molars (iMini-M), or inverted mini-hyrax supported on the first premolars (iMini-B).Materials and Methods:A total of 40 patients with transverse maxillary deficiency who were submitted for rapid maxillary expansion were divided in four groups according to type of expander used. Cone-beam computed tomography images were taken before and 3 months after expansion. One-way analysis of variance was used to analyze the differences among the groups, and paired t-tests were used to evaluate the changes in each group.Results:All groups showed a significant increase in the anterior maxillary width, with no intergroup differences. The iMini-B was the only group that did not show a significant increase in the posterior maxillary width. The intergroup comparison demonstrated differences among all groups except between Hyrax and iMini-M, which showed the greatest posterior expansions. The intragroup analysis showed a significant increase in the nasal passage volume in hyrax and inverted mini-hyrax on the molar groups, but the intergroup comparison revealed a significant difference only between Fan-Type and inverted mini-hyrax on the molars. None of the expanders caused significant changes in the oropharyngeal measurements.Conclusions:Only the Hyrax and inverted mini-hyrax on the molar expanders effectively increased the nasal passage volume, and none of the expanders evaluated in this study modified the oropharyngeal airway.     

Orthopedic outcomes of hybrid and conventional Hyrax expanders:: Secondary data analysis from a randomized clinical trial

ObjectivesTo compare the effects of a hybrid miniscrew-supported expander versus a conventional Hyrax (CH) expander in growing patients.Materials and MethodsForty patients were randomized into two groups: a hybrid Hyrax (HH) expander group using a Hyrax expander with two miniscrews and a CH expander group. The final sample had 18 subjects (8 female, 10 male; initial age of 10.8 years) in the HH group and 14 subjects (6 female, 8 male; initial age of 11.4 years) in the CH group. Cone-beam computed tomography examinations and digital dental models were obtained before expansion and 11 months postexpansion. The primary outcomes included the orthopedic transverse effects of expansion. Intergroup comparison was performed using analysis of covariance (P < .05).ResultsSignificantly greater increases in the nasal cavity width, maxillary width, and buccal alveolar crest width were found for the HH group. No intergroup differences were observed for dental arch width or shape changes.ConclusionsThe HH group showed greater increases in the nasal cavity width, maxillary width, and buccal alveolar crest width. No differences were observed for intermolar, interpremolar, or intercanine widths; arch length; or arch perimeter. Arch size and shape showed similar changes in both groups.     

Cephalometric evaluation of rapid and slow maxillary expansion in patients with BCLP: Secondary data analysis from a randomized clinical trial

Objective:To compare the dentoskeletal effects of rapid (RME) and slow (SME) maxillary expansion in patients with bilateral complete cleft lip and palate (BCLP).Materials and Methods:This was a secondary analysis of a previous randomized controlled trial (RCT). Forty-six patients (34 male, 12 female) with BCLP and posterior crossbite (mean age of 9.2 years) were randomly assigned to two study groups. Group RME comprised subjects treated with Haas/Hyrax expander. Group SME included patients treated with quad-helix appliance. Cone-beam computed tomography (CBCT) was performed before expansion (T1) and after appliance removal at the end of a 6-month retention period (T2) for a previous RCT that compared the transverse skeletal effects of RME and SME. CBCT-derived cephalometric images were generated and cephalometric analysis was performed using Dolphin Imaging Software (Chatsworth, Calif). Intergroup comparisons were performed using t tests (P < .05).Results:Baseline forms were similar between groups. No significant differences between RME and SME groups were found.Conclusions:Rapid and slow maxillary expansion produced similar sagittal and vertical changes in patients with BCLP. Both Haas/Hyrax and quad-helix appliances can be used in patients with vertical facial pattern. Clinical relevance: RME and SME can be equally indicated in the treatment of maxillary arch constriction in patients with BCLP.     

上颌骨牵引成骨术矫治上颌牙弓狭窄

目的 观察上颌骨牵引成骨术矫治上颌牙弓狭窄的疗效。方法 对１０例成年患者行上颌Ｌｅ Ｆｏｒｔ Ｉ型截骨术（不移动骨块）,并手术截开腭中缝骨联结。以上颌快速扩弓装置（６４１４６带环）,每日打开螺旋４次,共１．０ｍｍ。其中２例行单侧扩大牙弓,矫正上颌单侧牙弓宽度不足。利用计算机图形数据分析系统对扩弓前后的后前位头颅定位片进行测量（上颌骨、上颌牙弓基骨、上颌后牙间的宽度）并通过上颌前部咬合片观察腭中缝的     

Rapid maxillary expansion--tooth tissue-borne versus tooth-borne expanders: a computed tomography evaluation of dentoskeletal effects

This study evaluated rapid maxillary expansion (RME) dentoskeletal effects by means of computed tomography (CT), comparing tooth tissue-borne and tooth-borne expanders. The sample comprised eight girls aged 11 to 14 years presenting Class I or II malocclusions with posterior unilateral or bilateral crossbite that were randomly divided into two treatment groups, palatal acrylic (Haas-type) and hygienic (Hyrax) expanders. All appliances were activated up to the full seven mm capacity of the expansion screw. The patients were subjected to a spiral CT scan before expansion and after a three-month retention period when the expander was removed. One-millimeter-thick axial sections were scanned parallel to the palatal plane, comprising the dentoalveolar area and the base of the maxilla up to the inferior third of the nasal cavity. Multiplanar reconstruction was used to measure maxillary transverse dimensions and posterior teeth inclination by means of a computerized method. The results showed that RME produced a significant increase in all measured transverse linear dimensions, decreasing in magnitude from dental arch to basal bone. The transverse increase at the level of the nasal floor corresponded to one-third of the amount of screw activation. Tooth-borne (Hyrax) and tooth tissue-borne (Haas-type) expanders tended to produce similar orthopedic effects. In both methods, RME led to buccal movement of the maxillary posterior teeth, by tipping and bodily translation. The second premolars displayed more buccal tipping than the appliance-supporting teeth. The tooth tissue-borne expander produced a greater change in the axial inclination of appliance-supporting teeth, especially first premolars, compared with the tooth-borne expander.