Closure of the anterior open bite using mandibular sagittal split osteotomy

Anterior open bite is a common problem in orthognathic practice that confers functional and aesthetic handicaps on affected patients. Its management varies, and it is one of the most challenging disorders to treat. The orthodontic and surgical approach to the treatment of skeletal anterior open bite is still debated, and the results are controversial. The relapse rate is high with all the techniques in current use. The cause of relapse is multifactorial and one of the main factors is the type of osteotomy used. Over the last 30 years preference has moved from mandibular sagittal split osteotomy (MSSO) alone, to maxillary procedures only, or to bimaxillary operations, with maxillary procedures alone being thought to confer the best stability and predictability. The aim of this study was to evaluate the results of correction of anterior open bite with the MSSO immediately after operation, and 1 year postoperatively.     

双侧升支矢状劈开截骨后退下颌术后骨的稳定性的研究

目的：探讨双侧升支矢状劈开截骨术（BSSRO）后退下颌骨以钢丝结扎固定两骨段加颌间固定术后骨的稳定性，了解导致复发的有关因素。方法：双侧下颌升支矢状劈开截骨手术后退下颌的患者14例，于手术前1周，手术后1周，术后6个月分别拍摄定位头颅侧位片及许勒位X线片，用于测量下颌移动的距离及确定下颌骨髁状突的位置。结果：双侧下颌升支矢状劈开截骨后退术后，6个月的复发率为27.2%，多元逐步回归分析示下颌后退的距离与复发相关。结论：BSSRO后退下颌骨的距离越大，术后下颌骨向前移位的可能越大。     

Obwegeser II osteotomy (transoral angle osteotomy) for open bite with skeletal class III deformity

IntroductionThis study evaluated postoperative stability after Obwegeser II osteotomy (transoral angle osteotomy, first reported by Obwegeser 1973) for severe open bite with mandibular prognathism.Patients and methodsThis retrospective study reviewed 20 consecutive patients who underwent only mandibular Obwegeser II osteotomy to correct open bite and mandibular prognathism. Lateral cephalograms were evaluated preoperatively (T1), immediate postoperatively (T2) and at least 6 months after the surgery (T3). Surgical and postsurgical changes in cephalometric measurements were evaluated statistically.ResultsOpen bite with skeletal class III malocclusion was corrected by the Obwegeser II osteotomy alone. After an average of 9.9 ± 5.2 mm of mandibular setback with open bite closure (T2–T1, over-bite change, 5.7 ± 2.4 mm) by counter-clockwise rotation of the mandible, the patients showed 0.8 ± 1.7 mm of horizontal relapse (p > 0.05), 1.1 ± 1.7 mm of vertical relapse at the B point (p = 0.011) and −0.2 ± 1.6 mm of over-bite change postoperatively (T3–T2).DiscussionWith the adequate control of the condylar position with rigid internal fixation, Obwegeser II osteotomy showed acceptable stability after the correction of open bite with mandibular prognathism without a simultaneous maxillary osteotomy. An isolated Obwegeser II osteotomy can be considered a reliable option in cases with moderate to severe open bite with mandibular prognathism when the maxillary osteotomy is not needed if the patients have a well-positioned maxilla.     

Unusual cause of iatrogenic anterior open bite after bilateral sagittal split mandibular advancement osteotomy

We describe a case of anterior open bite after bilateral sagittal split mandibular advancement osteotomy. The discrepancy in height between the proximal and distal segments at the osteotomy sites damaged the soft tissue and caused bony interferences. Removal of the maxillary third molars and bilateral removal of bony interferences of the distal segments using a bur led to full resolution and a good orthognathic outcome on follow-up.     

Skeletal stability and condylar position related to fixation method following mandibular setback with bilateral sagittal split ramus osteotomy

PurposeTo investigate postoperative intersegmental displacement and relapse following bilateral sagittal split ramus osteotomy (BSSRO) by comparing three different fixation methods: group A (sliding plate), group B (miniplate) and group C (bicortical screws).Materials and methodsThe present retrospective study included 55 patients with mandibular prognathism who were treated with BSSRO. To evaluate skeletal changes, cone-beam computed tomography was taken before surgery (T0), three days after surgery (T1), and 6 months after surgery (T2). Differences among the three groups were assessed using a one-way analysis of variance, where P < 0.05 was accepted as statistically significant.ResultsThere were no significant differences among the three groups in demographic data and the amount of mandibular setback. In skeletal changes and condylar axis changes, there were no statistically significant differences among the three groups. However, there were statistically significant postoperative skeletal changes in group C (bicortical screws) at all landmarks. The mean horizontal relapse rate was 1.9% in group A (sliding plate); 4.8% in group B (miniplate); and 15.4% in group C (bicortical screws).ConclusionThe sliding plate system has good adaptability to the proximal segment after mandibular setback with BSSRO, and behaves according to semi-rigid fixation principles.     

Effect of fixation method on intergonial width stability after mandibular setback via bilateral sagittal split osteotomy

Q4: Horizontal changes occur following bilateral sagittal split osteotomy (BSSO) in skeletal class III patients. The aim of this study was to assess the ostoperative changes in intergonial (IG) width and compare them between the positional screw and miniplate fixation methods in BSSO. This study evaluated patients who had mandibular prognathism and underwent BSSO for mandibular setback. Internal fixation was performed bilaterally, either with positional screws in the lateral ramus or with a miniplate. Postero-anterior cephalograms were obtained preoperatively (T1), at 1 month postoperative (T2), and at 6 months postoperative (T3). The IG widths and the alterations in IG width postoperative (T2 − T1, T3 − T2) were measured. No correlations were observed between the amount of setback and changes at T2  − T1 or T3 − T2. The IG width values decreased after mandibular setback and internal fixation with both methods. Statistical analyses showed a significant difference between T3 and T1 in the miniplate group (P = 0.045). No significant difference in the postoperative change in IG width (T2 − T1 and T3 − T2) was found between the two fixation groups. The magnitude of this change was smaller for positional screws when compared to miniplates for fixation. The amount of mandibular setback showed no correlation with postoperative changes in IG width..     

Comparison of stability of mandibular segments following the sagittal split ramus osteotomy with poly-l-lactic acid (PLLA) screws and titanium screws fixation

The purpose of this study was to retrospectively compare the stability of the mandible following the surgical orthodontic treatment by sagittal split ramus osteotomy (SSRO) and orthodontic multi-bracket treatment using fixation methods with poly-l-lactic acid (PLLA) or titanium screws. The sample examined was 23 subjects with PLLA screws (PLLA group) and 22 subjects with titanium screws (Titan group). Lateral cephalometric radiographs were reviewed before surgery (T0), 2–3 days after surgery (T1), 1 month after surgery (T2), and after postoperative orthodontic treatment (T3) and changes in the position of bony segments were examined by cephalometric linear and angular measurements. A similar movement of the mandible following setback surgery was indicated, and statistical analysis showed no significant differences in skeletal changes between the two groups during whole postoperative periods. However, a relapse following surgical counterclockwise rotation of the distal segment in PLLA group tended to be slightly greater during T1–T2 compared with Titan group. These results suggest that a use of the PLLA screw fixation may not influence on the stability of bony segments after mandibular setback surgery by SSRO during the postoperative period, although a slight tendency for clockwise rotation of the distal segment was indicated in patients with PLLA screws. It is suggested that fixation of bony segments with PLLA screws after SSRO may be effective in properly selected cases.     

Immediate mechanical stability of sagittal split ramus osteotomy fixed with resorbable compared with titanium bicortical screws in mandibles of sheep

Ten fresh mandibles from adult sheep were stripped of all soft tissues and sectioned in the midline. We did sagittal split osteotomies and 5 mm advancement on all the 20 hemimandibles. Ten hemimandibles were fixed with three 2.0 mm x 13 mm titanium bicortical screws, and the other 10 were fixed with three 2.0 mm x 13 mm poly-l-lactic acid/polyglycolic acid (PLLA/PGA) bicortical screws in an inverted L pattern. All the hemimandibles were then mounted in a servohydraulic testing unit and tested to permanent deformation. Maximum forces that the mandibles resisted before breaking, maximum displacements, and the displacement values under 20, 60, 120, and 150 N were compared using the Mann-Whitney U-test. There were no significant differences in stability between the bones fixed with titanium and those fixed with resorbable screws.     

Skeletal open bite correction by combined Le Fort I osteotomy and bilateral sagittal split of the mandibular ramus

Of over 300 surgically-treated skeletal open bite cases, 10 were corrected by simultaneous repositioning of the maxilla and mandible by means of a Le Fort I osteotomy and bilateral sagittal splitting of the mandibular ramus. The paucity of cases does not permit detailed statistical evaluation; however of the many parameters investigated, certain appeared to be associated with relapse in this series: short intermaxillary fixation period, skeletal class II, and the surgeon. Despite skeletal relapse in 3 cases, dental compensation precluded the need to re-operate on any of these relapsed cases. This surgical approach to the correction of a skeletal open bite, when indicated on aesthetic and occlusal grounds, is a particularly suitable method, and gives stable results.     

MRI changes in the temporomandibular joint following mandibular setback surgery using sagittal split ramus osteotomy with rigid fixation

Objectives: This study examined the changes in temporomandibular joint dysfunction (TMD) symptoms and investigated the variations in the disc position, disc and condylar morphology following sagittal split ramus osteotomy (SSRO) with rigid fixation in patients with mandibular prognathism. Furthermore, the authors examined the correlation between mandibular setback and TMD symptoms.

Methods: The study included 24 Japanese patients with jaw deformities who were treated using bilateral SSRO and Le Fort I osteotomy. The clinical and magnetic resonance imaging findings in the temporomandibular joint were evaluated preoperatively and at three and six months postoperatively.

Results: The preoperative TMD symptoms were significantly associated with the prevalence of TMD symptoms at six months postoperatively. Anterior disc displacement improved in four joints with slight displacement and with no morphological change. There were no postoperative changes in condylar morphology. There was no significant correlation between mandibular setback and the postoperative TMD symptoms.

Conclusion: Postoperative TMD symptoms may be influenced mainly by preoperative TMD symptoms rather than mandibular setback using SSRO with rigid fixation. Therefore, patients with TMD symptoms require physical examination and MRI for appropriate diagnosis preoperatively.     

评价颌间结扎钉配合小型钛板联合治疗下颌骨骨折的临床应用

目的：评价颌间结扎钉进行颌间牵引固定的疗效。方法：对63例下颌骨骨折切开复位内固定的患者随机采用牙弓夹板或颌间结扎钉进行颌间牵引固定，比较操作时间、治疗后牙周指数、张口度、咬合关系及骨折愈合情况。结果：采用颌间结扎钉治疗的患者咬合关系、骨折愈合及张口度与采用牙弓夹板的患者无明显差别，其操作时间较采用牙弓夹板明显缩短，牙周健康指数明显好于采用牙弓夹板的患者。结论：颌间结扎钉操作简单省时、易于保持口腔清洁，是较理想的颌间牵引固定新方法。     

下颌骨双侧升支矢状劈开双皮质螺钉内固定的生物力学分析

目的:对下颌骨升支矢状劈开不同方式双皮质固位螺钉内固定进行三维有限元分析,为临床提供理论指导。方法:建立下颌骨升支矢状劈开6种双皮质螺钉固定方式的三维有限元模型;计算不同固定方法在3种咬合情况下颌骨的应力、内固定系统的应力以及骨劈开处的位移,对比这些固定方式的固定效果以及不同咬合情况对固定稳定性的影响。结果:在相同咬合情况下,颌骨的应力、内固定系统的应力以及劈开处的位移的大小情况如下:单纯上缘固定大于倒"L"型固定;直径2.0mm大于直径2.7mm螺钉固定;倒"L"型60°大于倒"L"型90°和120°固定;间距2.0cm大于间距3.0cm固定。相同固定方式情况下,颌骨的应力、内固定系统的应力以及劈开处的位移从大到小排列顺序为:前牙咬合、前磨牙咬合、磨牙咬合。结论:双皮质固位螺钉内固定的排列方式,如:间距、角度、位置和内固定系统的规格均对固定稳定性有不同程度的影响;前牙咬合对固定的不良影响最大,应尽量避免。     

无托槽隐形矫治技术治疗高角型开 畸形

目的探讨无托槽隐形矫治技术治疗高角型开 畸形的临床应用并评估其疗效。 方法选取高角型开 畸形患者30例,其中男12例、女18例,年龄18 ~ 30岁,平均24.5岁,应用无托槽隐形矫治技术进行正畸治疗,均采取拔牙矫治,治疗前后拍摄头颅侧位片,测量头影测量指标并使用SPSS 17.0统计学软件进行统计学分析。 结果30例患者矫治后前牙覆 恢复正常,面型得到明显改善。SNA角减小1.6°（P<0.001）,SNB角减小0.5°（P = 0.038）,ANB角减小1.1°（P<0.001）,GoGn-SN角减小1.7°（P<0.001）,U1-NA减小3.7 mm（P<0.001）,L1-NB减小1.8 mm（P = 0.001）,U1-L1角增加16.6°（P<0.001）,U1-SN角减小8.2°（P<0.001）,OPP-SN角减小5.3°（P = 0.012）,FH-PP角减小0.9°（P = 0.041）,差异均有统计学意义;U6-PP减小0.6 mm（P = 0.091）,L1-MP角减小0.6°（P = 0.058）,差异无统计学意义。 结论无托槽隐形矫治技术治疗高角型开 畸形能有效进行垂直向控制,使下颌平面逆时针旋转,获得良好疗效。     

Multiloop edgewise archwire treatment for a patient with a severe anterior open bite and amelogenesis imperfecta

Amelogenesis imperfecta is a rare hereditary disorder that affects dental enamel and is often associated with an anterior open bite. Orthodontic treatment of a 16-year-old female patient with hypocalcified amelogenesis imperfecta and a 9-mm anterior open bite was presented. Radiographic examination revealed a steep mandibular plane angle, an increased lower face height, a Class II skeletal pattern, and a convex profile. Additionally, the patient had stainless steel crowns on all upper and lower posterior teeth and composite veneers on the upper anterior teeth. The patient was treated nonsurgically using a multiloop edgewise archwire (MEAW). MEAW mechanics allowed for successful correction of the anterior open bite, with significant reduction in the mandibular plane angle and improvement in the patient''s profile. No fixed retainers were used, and the results remained stable 78 months after removal of orthodontic appliances. MEAW mechanics should be considered for patients with large anterior open bites, although this technique requires excellent patient compliance.     

Nonsurgical and nonprosthetic camouflage treatment of skeletal Class II open bite with bilaterally missing lower first molars

This report illustrates the successful nonsurgical and nonprosthetic camouflage treatment of a skeletal Class II open bite malocclusion combined with missing mandibular first molars bilaterally. In the mandible, the second and third molars were uprighted and protracted, substituting for the missing first molars. In the maxilla, anterior bodily retraction and full-arch intrusion were achieved following premolar and second molar extraction, which also induced autorotation of the mandible. The treatment outcome and prognosis were confirmed with three-dimensional superimposition techniques, along with long-term stability.     

Stability of the mandible after bilateral sagittal split osteotomy: Comparison between positioning screws and plate

Relapse is one of the complications of orthognathic surgery. In this study, we compared the stability of mandibular bilateral sagittal split osteotomy by using two different methods of fixation. In Group 1, eight patients with prognathic mandible underwent BSSO and set back average of 6.0 mm. The method of fixation was positioning screws. In Group 2, eight patients with prognathic mandible underwent BSSO and set back average of 6.0 mm. The method of fixation was plate and monocortical screws. In Group 3, eight patients with retrognathic mandible underwent BSSO and advancement average of 6.0 mm. The method of fixation was positioning screws. In Group 4, eight patients with retrognathic mandible underwent BSSO and advancement average of 6.0 mm. The method of fixation was plate and monocortical screws. The results showed in terms of advancement that there was no significant difference between the groups after one year. However, in terms of set back, this study showed significant difference.     

Effect of maxillary and mandibular extrusion arches on dentoskeletal changes in adults with anterior open bite: a quantitative analysis

ObjectiveTo quantify dentoskeletal changes accompanying the use of extrusion arches during the treatment of anterior open bite (AOB) in adults.Materials and MethodsA total of 23 adult patients with an AOB of −3.05 mm ± 1.27 mm were treated with upper and lower extrusion arches after the alignment phase. Lateral cephalograms were taken before placement of the extrusion arch, immediately after closure of the open bite (T2), and at the end of orthodontic treatment (T3). Data were statistically analyzed using repeated-measures analysis of variance and the Bonferroni post hoc test for pairwise comparisons (α = 0.05).ResultsSuccessful closure of AOB, with an overall change in overbite of 4.73 ± 1.93 mm, was achieved in an average of 3.8 months and remained stable at T3. Upper and lower incisors were significantly extruded by 2.05 mm ± 0.72 mm and 2.54 mm ± 1.63 mm, respectively, and significantly retroclined by 6.36° ± 1.63° and 8.45° ± 3.83°, respectively, with a resultant increase in the interincisal angle of 12.80° ± 2.09°. Statistically significant intrusion and mesial tipping (P < .001) of the maxillary and mandibular first molars were observed at T2. Dentoskeletal changes remained stable at T3, except for a significant reduction of the mesial tipping of the maxillary and mandibular first molars.ConclusionsThe combined use of maxillary and mandibular extrusion arches resulted in significant favorable dentoskeletal changes that led to the successful closure of AOB during a short duration of treatment.     

Contributing factors to intraoperative clockwise rotation of the proximal segment as a relapse factor after mandibular setback with sagittal split ramus osteotomy

The aims of this study were to analyze possible contributing factors to intraoperative clockwise rotation (CWR) of the proximal segment (PS), which is known to be a primary factor for relapse after mandibular setback with sagittal split ramus osteotomy (SSRO) and to evaluate the correlation between the CWR of the PS and relapse tendency. The sample was comprised of 47 patients who underwent SSRO for mandibular setback. Lateral cephalograms were analyzed. The vertical difference between the inferior borders of the PS and the distal segment at the vertical osteotomy line for SSRO after setback of the distal segment (vertical bony step, VBS) was the most predictable factor for CWR of the PS (p < 0.001), and it correlated significantly with the gonial angle, the surgical change in SNB, and the downward movement of the maxilla (p < 0.05). Patients with large CWR of the PS showed a greater tendency in horizontal relapse than patients with small CWR of the PS (p < 0.05). Such relapse patterns could be prevented with adequate surgical planning designed to reduce the VBS, such as maxillary posterior impaction or the intentional guidance of the PS to maintain the original position of the PS without CWR.     

Skeletal stability following bilateral sagittal split osteotomy (BSSO) with and without condylar positioning device.

PURPOSE: The goal of this retrospective study was to investigate whether utilization of condylar positioning devices in comparison to the manual positioning technique has a favorable influence on skeletal stability after bilateral sagittal split osteotomy. PATIENTS AND METHODS: Lateral cephalometric radiographs of 49 patients who had undergone bilateral sagittal split osteotomy or bimaxillary surgery at the Universitiy Hospital of Aachen between 1993 and 2003 were evaluated with the aid of analysis software (Adda Keph version 3.0, JR - datentechnik, Leipzig, Germany). As a criterion for skeletal stability the postoperative changes of SNB angle and Wits appraisal were determined. In 10 of 28 patients with mandibular advancement and in 10 of 21 individuals with mandibular setback, the Luhr positioning device was used intraoperatively to reproduce the condylar position. Mandibular joints of the remaining patients were positioned manually. The results were statistically worked up by means of unrelated t test at P = .05. RESULTS: Neither in advancement nor in setback surgery did the positioning device technique result in better outcomes for postoperative changes of SNB angle and Wits appraisal. The confidence intervals rather suggest equivalence of the data in both groups. CONCLUSION: The use of positioning appliances does not lead to an improvement of skeletal stability. With the manual technique, equally stable results can be attained in advancement as well as in setback surgery.