Rehabilitation of long-term mandibular defects by whole-process digital fibula flap combining with implants: A case report

Currently, the gold standard and workhorse in mandibular reconstruction is the free vascularized fibula flap. Particularly for patients who have had mandibulectomy for a long time, it is still difficult to precisely reconstruct the mandibular contour and successfully restore the patient's chewing function and esthetics. For the restoration and rehabilitation of long-term mandibular abnormalities, three-dimensional (3D) virtual surgical planning (VSP) and 3D-printed surgical guides are essential. Digital design and manufacturing were used to improve the accuracy of prostheses and facilitate occlusal reconstruction. Therefore, equipped with the methods of 3D VSP, 3D-printed surgical guides, free vascularized fibular flap, and immediate dental implants, this clinical report provides a feasible solution for mandibular reconstruction.     

Posterior maxillary segmental osteotomy for mandibular implants placement: case report

The loss of mandibular molars can result in a maxillary dentoalveolar extrusion, leading to an insufficient interarch space. In severe cases, this space must be regained before the prosthetic reconstruction of the opposite edentulous area. The posterior maxillary segmental osteotomy (PMSO) is a simple but precision technique to manage this problem; without which one can achieve a good surgical outcome but a poor final occlusion. The purpose of this paper was to present a case of PMSO for mandibular implant placement and to discuss the important steps.     

Comprehensive virtual orthognathic planning concept in surgery-first patients

The surgery-first concept is becoming increasingly popular in orthognathic surgery since it offers major advantages such as a reduction of treatment duration and an increase in patient satisfaction by eliminating phases of presurgical orthodontic decompensation. Here, we present a novel interdisciplinary pathway of a fully virtual orthodontic-surgical planning concept in a surgery-first setting using a 3D-printed cutting guide and a customised maxillary implant for the Le Fort I osteotomy as well as a CAD/CAM-based stereolithographic final splint. Patient data from cone-beam computed tomography of the skull and a full arch dental scan were processed using the OnyxCeph^3TM software (Image Instruments). A mutual computer-aided surgical simulation was conducted by the orthodontist and the oral and maxillofacial surgeon to determine the three-dimensional maxillary and mandibular movements. In a separate virtual planning session, the surgeon designed a customised maxillary guide and implant for precise intraoperative transfer (Geomagic Freeform Plus software, 3DSystems). A 3D-printed CAD/CAM-based final splint was fabricated by the orthodontist and used for accurate mandibular repositioning. We established a comprehensive virtual interdisciplinary orthognathic workflow and successfully applied this concept with a high level of accuracy in a series of surgery-first patients with different types of dentofacial anomalies. This novel fully computer-based pathway offers a high potential to improve the outcomes of orthognathic surgery and reduce total treatment time in the management of the orthognathic patient.     

Bilateral sagittal split osteotomy training on mandibular 3-dimensional printed models for maxillofacial surgical residents

Complications with bilateral sagittal split osteotomy (BSSO) can sometimes result from surgical inexperience. Our aim was to present a 3-dimensional printed mandibular model for BSSO training in a maxillofacial surgical education programme. A polymethacrylate mandibular model obtained from mandibular cone-beam computed tomographic (CT) images was designed and printed for use in training. Twenty-four residents were each asked to do a BSSO according to the Epker/Dal-Pont technique. The session was conducted as a simulation course with a final debriefing. A questionnaire before and after the test was filled in using a 10-point Likert scale to assess the participants’ knowledge. The mandibular model provided a realistic way of handling the trabecular bone after cortical osteotomy, as well as in the splitting phase. Significant increases in knowledge and surgical skills were noted for all steps of the BSSO, particularly regarding the use of the piezoelectric device for osteotomy, and for management of wisdom teeth in the splitting zone (3.00 ±2.16 to 6.95 ±2.06 and 2.73 ±1.91 to 5.75 ±2.63, respectively; p₁ = 0.0002 and p₂ = 0.0003). We think that this is a valuable printed mandibular model for the development of surgical skills for BSSO in maxillofacial surgical residents.     

Virtual planning and CAD/CAM-assisted distraction for maxillary hypoplasia in cleft lip and palate patients: Accuracy evaluation and clinical outcome

The aim of this prospective study was to report the experience with a specific guided distraction protocol for the treatment of CLP patients with severe midface hypoplasia.From January 2016 to April 2019, six consecutive, non-growing, CLP patients with maxillary hypoplasia underwent a specific distraction protocol based on the use of VSP, CAD/CAM-generated surgical splints, cutting guides, prebent internal maxillary distractors, early removal of distractors, and acute callus manipulation and fixation.STL files for VSP, using multislice CT scans taken preoperatively (T0) and 3 months after distractor removal (T1) were superimposed using the free software 3D Slicer and Geomagic Wrap to evaluate the accuracy of maxillary repositioning and assess 3D bone changes. Clinical outcome was evaluated at the 1-year follow-up (T2).The patients and surgeon were satisfied with the occlusal and aesthetic outcomes. A maximum difference of 2 mm between the VSP and the actual surgical outcome was chosen as the success criterion for accuracy. The average linear difference for selected points was <2 mm in four patients and >2 mm in two patients. The average distance of the postoperative maxilla from the VSP model was 2.28 mm (median 1.85), while the average forward movement of the maxilla was 10.18 mmThe protocol used is effective and accurate in the correction of severe maxillary hypoplasia in CLP patients. Early removal of the distractor and stabilization with plates reduces patient discomfort and does not jeopardize stability. This protocol should be reserved for complex cases due to the costs of the procedure, which are not negligible.     

3D vector analysis of mandibular condyle stability in mandibular setback surgery with bicortical bioabsorbable screw fixation

IntroductionBioabsorbable screws became widely used for stable fixation in orthognathic surgery as biomechanical technology advanced. Recently, 3D image analyses begin to be used to evaluate surgical changes. The purpose of this study was to evaluate, using 3D vector analysis, the stability of bicortical bioabsorbable screw fixation in mandibular setback using a sagittal split ramus osteotomy.Spatial change of the mandibular condyle was determined by 3D coordinates containing directional information.Materials and methodsBicortical screw fixation was performed using either a bioabsorbable screw (25 patients) or a titanium screw (5 patients) in orthognathic surgery. Pre- and post-operative CT images (6 months after surgery) were superimposed digitally. A 3D coordinate (X, Y, Z) and vectors were employed to quantify spatial changes of the condyle and analysed statistically.ResultsMeasuring on 3D image showed stable error about 0.16 mm. There were no significant differences in the total spatial changes of the condyle between titanium and bioabsorbable screws with the exception of the lateral–medial direction of the condylar centre (P = 0.042). The directional vector components were stable, regardless of mandibular setback.ConclusionIn 3D vector analysis, bioabsorbable screw fixation in SSRO with distal segment osteotomy shows clinically acceptable postoperative condylar position stability.     

三维头模设计及个体化模板引导技术在OSAHS患者下颌骨牵引成骨术中的应用

目的 探索术前三维头模设计及个体化模板引导在下颌骨牵引成骨术中的应用,并且评估手术的治疗效果.方法 选择原发或继发小颌畸形患者10例,均伴有中度或者重度的阻塞性睡眠呼吸暂停低通气综合征（obstructive sleep apnea-hypopnea syndrome,OSAHS）.根据三维螺旋CT的数据制作三维头模,在三维头模上模拟手术截骨以及牵引器的安放,制作个体化模板.术中应用个体化模板指导截骨线的位置以及牵引器的安放.术后5～7 d的间歇期后,开始以每天1 mm的速度行骨牵引至牵引结束.术后3～6个月二次手术去除牵引器.结果 10例患者顺利完成下颌骨牵引成骨治疗,第一次手术平均手术时间为（1.6±1.3）h.10例患者的20侧下颌骨平均牵引长度为（23.6±7.5） mm.术前睡眠呼吸暂停低通气指数（apnea and hypopnea index,AHI）为（37.1±13.7）次/h,睡眠时最低血氧饱和度（lowest oxygen desaturation,LSAT）为75.2％±18.4％;术后AHI为（2.7±4.8）次/h,LSAT为92.1％±5.3％.所有患者的牵引成骨区成骨良好,均未出现成骨不良、下牙槽神经损伤及牵引故障等严重并发症.结论 术前三维头模设计可以很好的模拟牵引成骨术中的截骨位置及牵引器的安放,避免损伤重要解剖结构;应用个体化模板引导可以提高下颌骨牵引成骨术截骨及牵引器安放的精确性,缩短手术时间,降低手术难度及风险.     

Morphometric Study of Mandibular Ramus Related to Sagittal Ramus Split Osteotomy and Osteosynthesis

ABSTRACT: The objective of this study was to quantify the cortical bone thickness of the mandibular ramus to determine conditions related to sagittal split ramus osteotomy and placement of screws. The patient sample comprised 44 subjects of ages ranging from 46 to 52 years (mean age, 49 years). The cone-beam computed tomography was performed and realized 3 cuts in the third molar area (section A), 5 mm posterior (section B), and 5 mm posterior to the latter (section C). Measurement in the cortical areas of the superior and inferior levels related to mandibular canal and measurement related to the total width of the mandible was executed. Intraclass correlation coefficient with P < 0.05 was used. The result showed that the buccal and lingual cortical zone did not present statistical differences, and the minor value was 1.5 mm for each one. There were no differences in the superior and inferior cortical bone, and the total width of the mandible was between 15.9 and 8.5 mm in the anterior area, between 17.4 and 12.8 mm in the middle area, and between 18 and 8.8 mm in the posterior area. The distance superiorly to the mandibular canal presented a minimal SD with a mean of 8.5 mm in the anterior region, 10.6 mm for the middle region, and 12.5 mm in the posterior region. In conclusion, the cortical thickness of the mandibular ramus in the adult population is particularly strong and offers a good anchorage for screw insertion in sagittal split ramus osteotomy.     

手术导板对后牙区不翻瓣手术精度的影响

目的:评价后牙缺失患者手术导板辅助实施不翻瓣手术对种植体植入精度的影响。方法:选取2009年3月—2010年6月后牙缺失进行不翻瓣种植手术患者38例,其中男19例,女19例,平均年龄(45.06±11.10)岁,分为非导航手术组和导航手术组2组,非导航手术组男10例、女9例,上颌缺失牙17颗,下颌缺失牙22颗,由手术医师目测决定种植体窝洞预备轴向;导航手术组男9例、女10例,上颌缺失牙14颗,下颌缺失牙17颗,应用手术导板辅助进行种植体窝洞预备。术后CT扫描,以种植体长轴为中心重建缺牙区冠状面和矢状面图像,以角度偏差5°、距离偏差2mm为标准,对种植体植入位置满意度计数,对下后牙缺失病例是否出现尖端接触舌侧骨皮质、有无影响种植体植入长度的种植体计数。应用Stata 7.0软件计算上述指标的百分率并进行2组间χ2检验。结果:经统计学检验分析,与非导航手术组相比,导航手术组种植体颊舌向和近远中向角度误差以及下颌后牙种植体到下颌神经管距离误差满意率较高,下颌后牙种植体尖端接触舌侧骨皮质的发生率较低,并且因骨皮质阻挡、影响种植体植入长度的发生率较低。结论:与非导航手术组相比,手术导板可降低种植体植入角度误差和骨皮质阻挡植入种植体的发生率,使种植体植入位置满意率更高,并显著提高下颌后牙缺失病例的种植体植入长度。     

Three-dimensional computed tomographic evaluation of morphologic airway changes after mandibular setback osteotomy for prognathism

OBJECTIVE: To observe changes in the pharyngeal airway and the hyoid bone position after mandibular setback osteotomy in 30 patients with mandibular prognathism by means of 3-dimensional computed tomography (3DCT). STUDY DESIGN: Preoperative and postoperative computed tomography (CT) examinations were performed on 17 patients treated by sagittal split ramus osteotomy with rigid osteosynthesis and on 13 patients treated by intraoral vertical ramus osteotomy without osteosynthesis. The amount of mandibular setback was measured by the preoperative to postoperative difference of the mandibular position in axial CT images. The sizes of the preoperative and postoperative pharyngeal airway were evaluated from semitransparent and crosscut 3DCT images. Postoperative displacement of the hyoid bone was evaluated by a technique to superimpose a postoperative hard tissue 3DCT image on the preoperative image. The helical scan technique was used in the CT examination. The volume rendering technique was used to create 3DCT images. RESULTS: The mean mandibular setback was 7.8 +/- 2.1 mm with a range of 5 to 11 mm. Three months after surgery, the lateral and frontal widths of the pharyngeal airway had decreased significantly in comparison with the preoperative width. The mean reduction rates of the lateral and frontal width were 23.6% and 11.4%, respectively. The diminished airway did not recover by either 6 months or 1 year after surgery in most cases. Downward and posterior displacement of the hyoid bone was seen postoperatively. There were positive correlations between the amount of mandibular setback and reduction of the lateral width of the pharyngeal airway (r = 0.54) and the amount of hyoid bone displacement (r = 0.42). There were no significant differences between the two surgical techniques. CONCLUSION: Three-dimensional computed tomography was a practical imaging technique to evaluate the morphologic airway changes. The pharyngeal airway may have irreversible narrowing after mandibular setback surgery.     

钛-镍记忆合金牵张成骨的新生骨骨密度及生物力学测试

目的通过对牵张成骨新生骨的骨密度和生物力学测试，研究钛-镍记忆合金牵张器牵张成骨的质量。方法选用成年杂种犬12只，下颌两侧拔牙后用全埋置钛-镍记忆合金牵张器完成牵张手术，左侧为实验侧，右侧为自身对照。分别在牵张完成后3、6个月进行双能x线骨密度测量和压缩生物力学测试。结果术后3个月，牵张区新生骨骨密度、抗压强度、弹性模量低于对照侧；6个月，各项指标均有增加，与对照侧的差异无统计学意义。结论用钛-镍记忆合金牵张器牵张，增高犬下颌后牙区牙槽嵴，新生骨质量可以满足种植等后期修复的要求。     

Mandibular midline distraction osteogenesis: a complex case with severe crowding

This article reports on a patient with severe maxillary and mandibular crowding treated by both expansion and extraction treatment. Two surgical procedures, surgically assisted palatal expansion and a mandibular midline osteotomy, were performed in sequence for skeletal expansion. A hybrid appliance, consisting of a Hyrax screw and 2 miniplates, was used in the mandible. Since expansion was not enough for relief of the crowding, 3 premolars were later extracted. The patient's final occlusion was satisfactory, but genioplasty may be desired in the future.     

Morphometric analysis of the Korean mandibular ramus for distraction osteogenesis using micro-computed tomography

When performing distraction osteogenesis, the osteotomy is normally applied to the cortical bone posterior to the mandibular second molar. We measured the topographic thickness of the cortical and trabecular bone of the mandibular ramus and at the mandibular canal (MC) to provide crucial anatomic data aimed at minimizing complications and elucidating the most appropriate site for placing the distractor. Forty sides of the mandibles were prepared from 20 Korean cadavers (10 men and 10 women with a mean age of 68 years). The specimens were scanned and reconstructed into three-dimensional images using a micro-computed tomography system. Coronal and horizontal sectional images of the mandibular ramus were taken at thickness intervals of 2 mm from the reconstructed three-dimensional images. Image analysis software was used to measure the thicknesses of the cortical and trabecular bone and to identify the locations of the MC within the body and the mandibular ramus on each section. The mean thicknesses of the buccal cortical plate, trabecular bone, and lingual cortical plate were 2.9 mm (men, 3.0 mm; women, 2.8 mm), 9.1 mm (men, 9.8 mm; women, 8.5 mm), and 2.2 mm (men, 2.3 mm; women, 2.1 mm), respectively. The distance from the buccal surface of the mandible to the MC increased from 5.3 to 10.0 mm (men, 5.3-10.0 mm; women, 5.3-9.1 mm) when moving progressively anterosuperior from the mandibular angle region. Morphometric analyses of the mandibular ramus can provide crucial data when performing mandibular osteotomy and locating an appropriate placement site for a distractor device during the distraction-osteogenesis procedure.     

Virtual and traditional surgical planning in orthognathic surgery – systematic review and meta-analysis

Traditional surgical planning (TSP) and virtual surgical planning (VSP) have been used in bimaxillary osteotomy planning. The time is taken in the planning and operating stages, and the working/doctor/total time of either approach are useful determinants of the efficiency of the operating method and quality of care. This systematic review and meta-analysis examined if VSP has a comparative advantage over TSP in the bimaxillary osteotomy. Cochrane Library, PubMed, EMBASE, and Google Scholar were used as databases to collect studies that met the outlined inclusion criteria based on PRISMA. Eight of 759 studies were considered to meet the eligibility criteria, and six fit for meta-analysis. The findings demonstrated significant VSP advantage over TSP in planning time (Z = 3.97 (p < 0.00001), WMD = ?5.29 (CI ?7.90 to ?2.68)). While more time-efficient than TSP, the difference with VSP was not significant during surgery (Z = 0.44 (p = 0.66), WMD = ?0.10 (CI ?0.51 to 0.34)). The study used random effects due to the high I² of the planning mean differences. The continued evolution of VSP and improved application knowledge will be important in reducing the time of planning and surgery, thus improving the outcomes of the complex bimaxillary osteotomy. The current evidence shows that VSP significantly performs better than TSP in reducing the bimaxillary osteotomy planning time, but the timing difference is not significant during surgery. Future analysis will benefit from using studies with standard research and reporting metrics and procedures, thus improving evidence-based clinical practice.     

Relapse related to pushing and rebounding action in maxillary anterior downgraft with mandibular setback surgery

Purpose

Maxillary downgraft (MD) and mandibular setback (MS) are problematic procedures in terms of postoperative stability. While the amount of intraoperative clockwise rotation (CWR) of the proximal segment (PS) after MS combined with MD has a positive correlation with the amount of MD, mandibular relapse after MS with MD in relation to intraoperative CWR of the PS has not been reported. Moreover, the effect of mandibular relapse on maxillary stability after MS with MD remains unclear. The purpose of this study is to evaluate mandibular and maxillary stability after MS with MD in relation to intraoperative CWR of the PS and amount of MD.

导航辅助山羊下颌体牵张成骨术的实验研究

目的：应用立体定向导航外科手术系统初步建立山羊单侧下颌骨牵张成骨术的研究方法,分析导航辅助牵张成骨术的精度。方法：选用成年山羊3只。局麻下在上颌骨植入5颗定位钉,用蜡片记录咬合关系后行颌间固定,将螺旋CT扫描数据导入AccuNavi1.0软件,进行三维测量与虚拟手术。全麻下,应用TBNavis-CMFS导航系统行下颌骨单侧体部牵张成骨术,牵引到位后,行CT扫描并同法进行测量,并应用Surgicase5.0软件测量牵引长轴间交角,与模拟手术结果进行比较。结果：山羊口内上颌前部定位钉出现松动,口外上颌两侧定位钉稳固。平均牵引长度为10.12mm（9.88-10.34mm）。三维测量分析显示,术后与术前模拟结果各指标间无显著性差异（P〉0.05）,牵引长轴交角均值为5.49°（4.70°～6.84°）。结论：选择口外入路的上颌骨区域植入钛钉作为山羊颌骨导航手术的配准方法精确性好。导航辅助山羊下颌骨牵张成骨术,可准确地将手术规划转移到实际手术中。     

Mandibular sagittal split osteotomy: is a bicortical 2-screw osteosynthesis adequate?

The aim of this study was to prospectively evaluate the accuracy and reliability of the use of the Hunsuck/Epker–type mandibular split osteotomy together with osteosynthesis with placement of 2 bicortical positioning screws without the adjunctive use of a postoperative maxilla-mandibular fixation in the treatment of mandibular dentofacial deformities. We analyzed the clinical and radiologic data of 54 patients with dentofacial deformities. We recorded age and sex, status of healing, and complications. Postsurgical complications that were recorded as minor did not require surgical intervention, whereas major complications required further surgical intervention. Fifty-one patients (94.5%) had a successful treatment outcome without complications, 13 patients (24%) developed minor complications, and 3 patients (5.5%) developed screw loosening requiring hardware removal and reosteosynthesis. The present study has demonstrated that Hunsuck/Epker–type mandibular split osteotomy together with osteosynthesis with placement of 2 bicortical positioning screws without the adjunctive use of a postoperative maxilla-mandibular fixation in the treatment of mandibular dentofacial deformities results in a low rate of major complications with a high rate of success     

A Cadaver-based Comparison of Sleeve-guided Implant-drill and Dynamic Navigation Osteotomy and Root-end Resections

IntroductionThis study compared the accuracy and efficiency of fully guided static and dynamic computer-assisted surgical navigation techniques for osteotomy and root-end resection (RER).MethodsFifty roots from cadaver heads were divided into two groups: fully guided static computer-assisted endodontic microsurgery (FG sCAEMS) and dynamic computer-assisted endodontic microsurgery (dCAEMS) (all, n = 25). Cone-beam computed tomography scans were taken pre and postoperatively. The osteotomy and RER were planned virtually in the preoperative cone-beam computed tomography scan and guided using 3D-printed surgical guides in the FG sCAEMS and 3D-dynamic navigation system in the dCAEMS. The 2D and 3D deviations and angular deflection were calculated. The osteotomy volume, resected root length, and resection angle were measured. The osteotomy and RER time and the number of procedural mishaps were recorded.ResultsFG sCAEMS was as accurate as dCAEMS, with no difference in the 2D and 3D deviation values or angular deflection (P > .05). The osteotomy and RER time were shortened using FG sCAEMS (P < .05). The FG sCAEMS showed a greater number of incomplete RERs than dCAEMS. Osteotomy volume, RER angle, and root length resected were similar in both groups (P > .05). FG sCAEMS and dCAEMS were feasible for osteotomy and RER.ConclusionsWithin the limitations of this cadaver-based study, FG sCAEMS was as accurate as dCAEMS. Both FG sCAEMS and dCAEMS were time-efficient for osteotomy and RER.     

Endoscopic mandibular osteotomy, and placement and activation of a semiburied distractor.

PURPOSE: The purpose of this study was to demonstrate the feasibility of endoscopic placement and activation of a semiburied distraction device in the porcine mandible. MATERIALS AND METHODS: Sixteen cadaver and two live anesthetized minipigs were used in this study. Access to the mandible was gained through two 1.0-cm submandibular incisions used for a working port and a visualization port. Under endoscopic visualization, dissection was carried sharply to the mandible and completed in the subperiosteal plane. Landmarks were identified through the endoscope, and a mandibular angle osteotomy was created. A semiburied distractor was then implanted, fixed to the mandible, and activated to create a bone gap. Finally, the site was explored through a submandibular incision to verify the accuracy of the endoscopic procedure. RESULTS: Endoscopic exposure; accurate identification of landmarks; creation of an osteotomy; and placement, fixation, and activation of a semiburied distractor were achieved in all 18 specimens. The inferior alveolar nerve was identified as the bone gap was expanded. CONCLUSION: The results of this study indicate that the endoscopic approach described here allows exposure and osteotomy of the mandible, and placement, fixation, and activation of a distractor. In the future, this technique will be used with totally buried, miniature distraction devices.     

Mechanical properties of three-dimensionally printed titanium plates used in jaw reconstruction: preliminary study

The aim of this study was to compare the mechanical properties of three-dimensionally (3D)-printed and conventional surgical plates used for the repair of maxillary or mandibular defects under the same experimental conditions, and to provide experimental evidence for the future application and clinical trial of 3D-printed individualized surgical plates. For the experimental group, two groups of surgical plates with thicknesses of 2.0 mm and 2.5 mm were designed and 3D-printed by electron beam melting, using Ti–6Al–4V as raw material. Conventional commercially available surgical plates with the same thickness were adopted as the control group. A Vickers hardness tester and universal testing machine were used to measure the mechanical properties of the plates (hardness, bending strength, tensile strength, and yield strength). The mechanical properties of 3D-printed surgical plates were significantly better than those of conventional surgical plates of the same thickness (P < 0.001). Comparing the surgical plates of different thickness, the 2.5 mm-thick plates had the highest bending strength in the experimental group (P < 0.001) and the best hardness (P < 0.001), bending strength (P = 0.001), tensile strength (P = 0.001), and yield strength (P = 0.001) in the control group. No statistical difference was found between the two kinds of plates in the experimental group in terms of hardness (P = 0.060), tensile strength (P = 0.096), and yield strength (P = 0.496). The 3D-printed surgical plates have better mechanical properties than the conventional ones.