Double contours and craniofacial morphology

This study was done to try to clarify the relationship between double contours and craniofacial morphology. The study sample included 56 pre-orthodontic patients with signs and symptoms of temporomandibular joint (TMJ) disorders. A comparison of craniofacial structures was done on 32 subjects with bilateral condylar bone change (BBC group: 28 female and 4 male) and 24 subjects with no condylar bone change (NBC group: 21 female and 3 male). The BBC showed significantly greater antegonial and ramus notch depths, as well as significantly more retruded mandibles, shorter ramus heights, and larger mandibular plane angles than the NBC. BBC subjects with bilateral double contours showed significantly more retruded mandibles, larger antegonial notch depth, and shorter lengths from the Sella to the Articulare than BBC subjects with no double contours. The study showed that important relationships exist between the presence of double contours and mandibular morphology and TMJ position.     

Craniofacial morphology and inclination of the posterior slope of the articular eminence in female patients with and without condylar bone change

This study investigated the association of craniofacial and glenoid fossa shapes and temporomandibular joint (TMJ) pathology in 39 orthodontic patients with signs and symptoms of TMJ disorders, using helical CT scans. Cephalometric measurements showed that 21 subjects with bilateral condylar bone change (BBC) had significantly smaller SNB angles, ramus heights and S-Ar/N-Ba ratios, as well as larger mandibular plane angles and lower anterior facial height than the 18 subjects with no condylar bone change (NBC). The average posterior slope of the left and right articular eminence in their central and lateral sections was significantly steeper in NBC than in BBC. Condylar bone change might, therefore, not only be related to the morphology of the mandible, but also of the glenoid fossa and cranial base. This appears to reflect adaptive changes in the condyle, articular eminence and cranial base in response to changes in loading.     

Condylar bone change and sagittal incisal and condylar paths during mandibular protrusive excursion

This study showed significant differences in sagittal condylar and incisal path angles during mandibular protrusive excursion, as well as flattening of the condylar path related to the existence and type of condylar bone change. Twenty-eight (28) patients with signs and symptoms of TMJ disorders were studied, using a six-degrees-of-freedom measuring device and helical CT. Sagittal incisal and condylar path angles at two mm and three mm condylar path lengths (CPL) were significantly shorter in the bilateral condylar bone change (BBC), compared to the no bone change (NBC) group. Also, NBC incremental sagittal condylar path angles from three to five mm CPL and NBC condylar path curvature at five mm CPL were both significantly larger than in BBC. Comparing types of bone change, incremental sagittal condylar path angles from three to five mm CPL was significantly less in osteophyte than in NBC or erosion groups. Condylar path curvature at five mm CPL was also significantly less in osteophyte than in NBC.     

Condylar bony change and mandibular deviation in orthodontic patients – using helical CT and MRI

This study was designed to assess the relationship between condylar bony change and mandibular deviation in the orthodontic patient. Seventy‐one patients were examined with helical computed tomography and magnetic resonance imaging to assess the condylar bony change and/or disk displacement prior to acceptance for orthodontic treatment. They were grouped into no condylar bony change (NBC) and unilateral condylar bony change (UBC). Frontal and lateral cephalograms and panoramic radiographs were also utilized to evaluate craniofacial morphology, and condylar and ramal heights. The results revealed that TMJ sounds occurred more in the UBC than the NBC group at all ages; but, TMJ pain and difficulty of mouth opening did not show remarkable differences. Erosion, a characteristic feature in age 9–13 years in UBC, occurred with normal disk position or disk displacement without reduction. Flattening exhibited normal disk position in age 9–13 years but was accompanied with disk displacement in age 14–18 years and 19 years and above. Osteophyte formation was highly associated with disk displacement without reduction in all age groups. Moreover, the UBC group's mandible was deviated to the ipsilateral side with significantly shorter condylar height on the affected side. In all age groups of UBC, the difference of condylar height was highly correlated with anterior maxilla, occlusal and gonial planes and with mandibular deviation. All aforementioned results suggest that unilateral condylar bony change can occur with normal disk position or ahead of disk displacement in the young patients. It seems that unilateral condylar bony changes can cause not only mandibular deviation but can also affect the cant of maxillary basal bone, mandibular plane angle and lower dentition.     

The depth of the mandibular antegonial notch as an indicator of mandibular growth potential

The craniofacial characteristics and growth potential of 25 orthodontically treated patients with deep mandibular antegonial notch were compared with a similar group of 25 shallow notch subjects by the use of longitudinal lateral cephalometric radiographs. Deep notch cases had more retrusive mandibles with a shorter corpus, smaller ramus height, and a greater gonial angle than did shallow notch cases. The lower facial height in the subjects with a deep mandibular notch was found to be longer, and both the mandibular plane angle and facial axis were more vertically directed. During the average 4-year period examined, the deep notch sample experienced less mandibular growth as evidenced by a smaller increase in total mandibular length, corpus length, and less displacement of the chin in a horizontal direction than did the shallow notch sample. The results of this study suggest that the clinical presence of a deep mandibular antegonial notch is indicative of a diminished mandibular growth potential and a vertically directed mandibular growth pattern.     

下颌骨缺损整复后颞下颌关节的变化

目的 :观察单侧或部分下颌骨缺损重建术后升支高度和下颌骨髁状突运动的变化。材料和方法 :30例患者按手术方式的不同分为两组 ,A组为保留髁状突的下颌骨部分切除、自体骨移植或病变骨冷冻再植整复组 ,B组为未保留髁状突组 ,术后通过X线检查评价结果。结果 :所有患者手术后都表现有不同程度的髁状突运动障碍。主要有升支高度降低、髁状突水平运动和转动能力降低 ,且A、B两组间存在明显差别 ,B组改变大于A组。结论 :下颌骨缺损重建对颞下颌关节结构和功能具有一定的影响 ,保留髁状突时所受影响要明显小于未保留髁状突组。因此保留髁状突有利于获得较好的术后功能效果     

髁突形态与覆深度关系的研究

目的　探讨髁突形态与不同覆深度的关系。方法　选择正常者、开畸形患者、覆正常的错畸形患者和深覆畸形患者各 5 0人 ,均为 18至 2 6岁成人。应用曲面断层片研究左右两侧的髁突形态 ,分别测量并计算上部髁突高度 /升支高度比 (UCH/RH)和髁突高度 /宽度比 (TCH/CW )。将髁突形态分为四种类型 :直立型 (类A) ,前倾型 (类B) ,后倾型 (类C)和尖型 (类D)。结果　开组的上部髁突高度相对升支高度明显小于其他各组 (P <0 0 0 1)。正常组的髁突形态比较粗壮 ,高度宽度比明显小于其他各组 (P <0 0 0 1)。类A和类B属于正常髁突形态 ,占正常组的 99%。类C和类D属于异常髁突形态 ,且在开组中的比例明显高于正常覆组或深覆组。另外 ,只有开组中显示上部髁突高度两侧不对称 (P <0 0 5 )。结论　开组髁突形态与其他各组相比明显不同。     

Relationship between bilateral condylar bone change and mandibular morphology: a study using morphometry

This study was undertaken to evaluate the relationship between bilateral condylar bone change (BCBC) and mandibular morphology. Thirty Japanese women with BCBC as diagnosed from computed tomographic scans were compared to 2 control groups: 26 Class I and 25 Class II Japanese women. All cephalograms were traced and scanned, and 14 homologous landmarks were digitized. Coordinates were used for cephalometric analysis, Procrustes analysis, Euclidean distance matrix analysis (EDMA), and thin-plate spline (TPS) analysis. Comparison of the cephalometric data for the BCBC and Class I groups revealed significant shrinkage in the condylar process and ramus height, in addition to a shorter body length. The centroid size showed that BCBC mean geometric forms were smaller than those of Class I and Class II. The landmark morphology of the BCBC group differed from both Class I and Class II, as shown by the residuals (P < .001). EDMA showed expansion of infradentale-pogonion (9.9%) and along the anterior slope height of the condyle (28.6%), while the posterior slope height decreased (21.6%). The vertical ramus height (gonioncondylion) also decreased by 11.8% in comparison to Class I. Compared to Class II, BCBC ramus height was shorter by 8.9%, condylar width decreased 13.7%, and the posterior condylar slope was 22% shorter. TPS analysis showed increased antegonial notching, a vertically expanded symphysis, and a collapsed and more horizontal condyle in the BCBC group. The combination of the above methods was very helpful in assessing mandibular morphology and showed that BCBC might be related not only to changes in the condyle, but may dictate changes in the rest of the mandible as well.     

髁突囊内骨折的临床特点和分类研究

目的：探讨髁突囊内骨折的临床特点,并提出一种能全面反映囊内骨折的分型,为临床制定治疗计划提供依据。方法：统计上海交通大学医学院附属第九人民医院口腔颌面外科关节组自1999—2008年住院手术和2007年6月—2008年12月门诊非手术治疗,经全景片和CT确诊为髁突囊内骨折的连续病例242例329侧,进行临床特点分析。部分病例经MRI检查观察关节盘移位情况。根据CT冠状位重建对囊内骨折进行分类,根据骨折线的位置,将髁突囊内骨折分为4型。A型骨折的骨折线位于髁突外1/3,B型骨折的骨折线位于中1/3,C型骨折的骨折线位于内1/3,M型骨折为粉碎性骨折。结果：囊内骨折占髁突骨折的66.8%,摔伤是主要的致伤原因。45%的囊内骨折合并下颌骨骨折。骨折侧下颌支残端外上方移位或脱位出关节窝的比例是8.8%,其中73%伴颏部或下颌体骨折。95%的囊内骨折伴关节盘前内侧移位。囊内骨折类型中,A型最多（155侧）,占47.8%;其次是B型（95侧）,占29.32%;M型（61侧）,占18.8%;C型最少（13侧）,占4%。结论：囊内骨折是下颌骨髁突骨折的最常见类型,易合并下颌骨骨折,导致下颌支残端移位或脱出关节窝。以冠状CT为主要依据的分类方法,能较全面地反映髁突囊内骨折的类型。     

Mandibular asymmetry in healthy children

Facial asymmetry is a naturally occurring phenomenon that is often due to differences in the mandibular dimensions on the right and left sides. The point where normal asymmetry turns abnormal cannot be easily defined, and no standards exist by which a judgement of abnormality can be made. The aim of the present study was to assess mandibular asymmetry in healthy children and its possible fluctuation during growth. The subjects consisted of 182 healthy children (88 girls, 94 boys) who had had an orthopantomogram taken at ages 7 (mean 7.5 years) and 16 (mean 15.9 years). On digitized orthopantomograms, condylar and ramus heights on both mandibular sides were measured with a Numonics Accugrid digitizer (Numonics Co., Montgomeryville, Pa., USA) and analysed with X-metrix software (Smart Systems, Turku, Finland). A paired t-test was used to determine the significance of the differences between the sides, and ANOVA to test the significance of the change in asymmetry during growth and between genders. The results revealed a statistically significant difference between the right and left sides in condylar height at age 7 years, in ramus height at both ages, and in the condylar and ramus height at age 16 years. The present study confirms that healthy young subjects generally have a statistically significant mandibular asymmetry, which, however, is only seldom clinically significant. The decision to initiate treatment because of asymmetry has to be carefully considered, since the study further showed that mandibular asymmetry may diminish or appear during growth of healthy subjects.     

Postoperative mandibular stability after orthognathic surgery in patients with mandibular protrusion and mandibular deviation

Skeletal stability and temporomandibular joint (TMJ) signs and symptoms were analyzed in 23 patients in whom mandibular protrusion and mandibular deviation had been corrected using bilateral sagittal split ramus osteotomy (BSSRO group, n = 10) and unilateral SSRO and intraoral vertical ramus osteotomy (USSRO+IVRO group, n = 13). Miniplate fixation was used in SSRO but no fixation was used in IVRO. The ratio of condylar bony change was 30.4% (7/23) and all condylar bony changes were seen on the deviated side. All preoperative signs and symptoms of TMJ disorders (4/13 patients in the USSRO+IVRO group and 2/10 patients in the BSSRO group) disappeared after surgery. Comparing the USSRO+IVRO group and the BSSRO group, in patients without condylar bony change, the mandible in both groups was stable anteriorly and horizontally after surgery, even though there was a larger horizontal mandibular movement in the USSRO+IVRO group during surgery. Comparing patients with condylar bony change versus no condylar bony change in the USSRO+IVRO group, postoperative horizontal mandibular displacement was significantly larger in the condylar bony change group than in the no condylar bony change group. These results support the idea that USSRO+IVRO can be useful in correcting mandibular deviation as well as improving signs and symptoms of TMJ disorders. However, it also seems important to be aware of the possibility of horizontal mandibular relapse in patients with condylar bony change.     

Static bone cavity in the condylar neck and mandibular notch of the mandible

This study presents the radiographic findings of two cases of static bone cavity in the inferior aspect of the condylar neck and mandibular notch of the mandible. On plain CT, a soft tissue mass was observed in each cavity. The submandibular gland and the other glands were not found in each cavity. On contrast-enhanced CT, the soft tissue in the cavity in the inferior aspect of the condylar neck had marked linear enhancement and dilated vasculature structure was observed in the cavity. On the contrast-enhanced MRI, the soft tissue in the cavity of the mandibular notch had marked enhancement and flow void was detected in the cavity. In the inferior aspect of the condylar neck, the cavity size had enlarged radiographically over a period of three years. Vascular lesions were found in the cavity located in the inferior aspect of the condylar neck and mandibular notch of the mandible by both CT and MRI. The vascular lesion might explain the enlargement of the static bone cavity.     

成人下颌孔的位置及下颌切迹和下颌支的测量

目的 通过对上海地区成人下颌骨的测量与分析，确定下颌孔的基本位置，并对下颌切迹的宽度、深度和下颌支的高度进行精确测量，旨在为临床提供解剖学参考。方法 取上海地区成人下颌骨，男74例，女79例，以下颌孔最大横径和最大纵径交点为下颌孔中心，测量其至下颌支后缘最近点的水平距离及下颌切迹最凹处的垂直距离，从而确定下颌孔的位置；以下颌切迹最宽处的距离测出下颌切迹的宽度，以下颌切迹最低点至喙突和髁突顶点连线的垂直距离测出下颌切迹的深度；同时测出髁突最高点至下颌角点的直线距离，作为下颌支的高度。结果 下颌孔至下颌后缘和下颌切迹的距离在成年男性平均为16．75mm、24．50mm；成年女性平均为：16．08mm、23．13mm。下颌切迹的宽度和深度在成年男性平均为34．20mm、15．33mm；成年女性平均为32．69mm、14．49mm。下颌支的高度男女平均为：61．62mm、57．19mm。结论 (1)下颌孔至下颌后缘的距离与下颌孔至下颌切迹最凹点的距离在男女间无明显差异。(2)下颌切迹的宽度与深度在男女间无明显差异。(3)下颌支的高度在男女间亦无明显差异。     

Evaluation of mandibular morphology in different facial types

The purpose of this study was to evaluate mandibular morphology in different facial types using various parameters. This study was conducted on lateral cephalograms of a total of 110 subjects, which included 55 males and 55 females between the age of 18-25 years having a mean of 22.3 years for males and 21.5 years for females. The sample was divided into normodivergent, hypodivergent, and hyperdivergent subgroups based on Jarabak's ratio. Symphysis height, depth, ratio (height/depth) and angle, antegonial notch depth, ramal height and width, mandibular depth, upper, lower, and total gonial angle, and mandibular arc angle were analyzed statistically and graphically. It was found that the mandible with the vertical growth pattern was associated with a symphysis with large height, small depth, large ratio, small angle, decreased ramus height and width, smaller mandibular depth, increased gonial angle, and decreased mandibular arc angle in contrast to mandible with a horizontal growth pattern. Sexual dichotomy was found with mean symphysis height and depth in the female sample being smaller than in the male sample, but symphysis ratio was larger in the female sample; males having greater ramus height and width, mandibular depth than females. The mandible seemed to have retained its infantile characteristics with all its processes underdeveloped in hyperdivergent group.     

颌下切口下颌升支垂直截骨在髁突高位骨折手术中的应用

目的:探讨应用颌下切口下颌升支垂直截骨术治疗髁突高位骨折的效果。方法:对16例(19侧)下颌骨髁突高位骨折患者采用颌下切口下颌骨升支后缘垂直截骨取出升支后缘骨块将骨折的髁突游离后取出,体外直视下将骨折片与升支后缘骨块复位固定后再回植,行颞下颌关节重建。结果:于术后6、12、24个月复查全部患者的开口度为30～48 mm,平均34.92 mm。所有患者咬合关系良好,无关节疼痛症状。部分病人有轻度开口偏斜,均<3 mm,有1例患者有关节弹响。结论:颌下切口下颌升支垂直截骨是治疗髁突高位骨折的一种可选择方法,具有操作简便、复位准确、近期疗效满意等优点。     

导致颞下颌关节强直的成人髁突骨折类型分析

目的: 回顾分析导致颞下颌关节强直的成人髁突骨折类型。方法：回顾口腔外科关节组2010—2012年收治的由髁突骨折保守治疗导致颞下颌关节强直,从损伤到发生强直有完整CT资料的成人病例,按照下颌支残端与关节窝的位置关系,将髁突骨折分为3级,0级为下颌支残端位于关节窝内,与之无接触;1级为下颌支残端位于关节窝内,与之有接触;2级为下颌支残端外上方脱位出关节窝。结合髁突骨折类型、骨折块移位程度和关节盘的位置、下颌骨其他部位骨折情况等,分析关节强直形成的原因。结果：13例(24侧)导致关节强直病例的髁突骨折有完整的CT资料,导致关节强直的髁突骨折类型均为囊内骨折,其中B型占70%。下颌支残端与关节窝的位置关系中,0级0侧;1级10侧,占41.7%;2级14侧,占58.3%。0级和1级的关节盘均伴髁突骨折块移位,后外侧带断裂。形成关节强直的髁突骨折中,77%伴颏部骨折,导致牙弓增宽。结论：下颌支残端与关节窝的位置关系对于预后判断有重要作用,其中0级不易引起关节强直;1级较容易引起关节强直,是手术的相对适应证;2级最容易引起关节强直,是手术的绝对适应证。其他危险因素还有髁突囊内B型骨折和合并牙弓增宽的下颌骨骨折。     

Comparison of osseous healing after sagittal split ramus osteotomy and intraoral vertical ramus osteotomy

The sagittal split ramus osteotomy (SSRO) is generally associated with greater postoperative stability than the intraoral vertical ramus osteotomy (IVRO); however, it entails a risk of inferior alveolar nerve damage. In contrast, IVRO has the disadvantages of slow postoperative osseous healing and projection of the antegonial notch, but inferior alveolar nerve damage is believed to be less likely. The purposes of this study were to compare the osseous healing processes associated with SSRO and IVRO and to investigate changes in mandibular width after IVRO in 29 patients undergoing mandibular setback. On computed tomography images, osseous healing was similar in patients undergoing SSRO and IVRO at 1 year after surgery. Projection of the antegonial notch occurred after IVRO, but returned to the preoperative state within 1 year. The results of the study indicate that IVRO is equivalent to SSRO with regard to both bone healing and morphological recovery of the mandible.     

Relations between anterior disc displacement and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle

In this study we investigated the relation between anterior disc displacement (ADD) and maxillomandibular morphology in skeletal anterior open bite with changes to the mandibular condyle. Thirty female patients (60 joints) with both conditions were evaluated. Magnetic resonance imaging of the temporomandibular joint (TMJ) was used to diagnose both ADD and changes to the mandibular condyle (erosion, osteophyte, and deformity). The relations among ADD, changes to the mandibular condyle, and maxillomandibular morphology were examined statistically. Changes to the mandibular condyle had a higher score than sym anterior open bite, the deviated side in asymmetric anterior open bite, and the non-deviated side. The score for disc displacement on the non-deviated side was lower than both the sym side and the deviated side. Unilateral changes to the mandibular condyle and unilateral disc displacement were not apparent in sym anterior open bite, but a unilateral non-displaced disc was seen only on the asymmetric side. Mandibular condylar changes were significantly more common on the deviated, than on the non-deviated, side. The SNB angle was significantly smaller, and the ANB, GZN, and SN-mandibular plane angles were significantly larger in sym anterior open bite. Overjet, ANB angle, GZN angle, and SN-MP angle were significantly larger, and the SNB angle was significantly smaller, in the presence of ADD without reduction and mandibular condylar deformity. We conclude that the prevalence of ADD without reduction and changes to the mandibular condyle were related to mandibular asymmetry and mandibular morphology in anterior open bite. This retrospective study suggests that ADD without reduction and mandibular condylar bone changes may be related to the progression of skeletal class II open bite and mandibular asymmetry in cases of skeletal open bite.     

三维CT成像诊断髁突骨折的临床研究

目的：探讨获得高质量颞颌关节三维ＣＴ影像的方法,评价其对髁突骨折的诊断价值。方法;对１４例髁突骨折患者,采用３种扫描方式（横断,冠状,螺旋）,２种扫描范围（横断位：眶耳平面上方１ｃｍ至下颌升支中份或颏下点。冠状位：乳突至下颌升支前缘或颏前点）。和２种层厚（２．５ｎｍ,５．０ｍｍ）扫描,以勾画法删除层面影像中的颈椎,茎突,枕骨和部分乳突,表面阴影显示法（ＳＳＤ）完成三维重建。     

Influence of edentulousness on gonial angle, ramus and condylar height

Summary  It has been shown that the shape of the mandible correlates with occlusal condition and the function of the masticatory muscles. Edentulous subjects have a wider gonial angle than dentate subjects, and a gender difference has also been shown. However, some studies have reported differing results. Less is known about the effect of dental status and gender on the ramus and condylar height. The aim of this study was to evaluate the association of tooth loss on the shape of mandible (i.e., gonial angle, ramus height and condylar height) in subjects aged 60 years and older. A total of 1036 subjects (667 dentate, 389 edentulous; 554 women and 482 men) were included in the study. Interviews and clinical and panoramic radiographic examinations were carried out. The gonial angle of the mandible and the mandibular and condylar height were measured using panoramic radiographs. In edentulous subjects, the gonial angle was significantly larger, while the ramus and condylar height was significantly smaller on both sides compared with dentate subjects. Women had a significantly larger gonial angle and smaller ramus and condylar height on both sides compared with men. In conclusion, the morphology of the mandible changes as a consequence of tooth loss, which can be expressed as a widening of the gonial angle and shortening of the ramus and condylar height. These findings highlight the importance of rehabilitation of the masticatory system to maintain good functioning of the masticatory muscles for as long as possible.