曲面断层片和头颅后前位片诊断下颌骨不对称的可行性探讨

目的:探讨曲面断层片和头颅后前位片在分析下颌不对称畸形中的作用。方法:人头颅骨标本5具,常规方法分别拍摄有钢珠标志和无钢珠标志的头颅标本的X线后前位定位片(PAC)和曲面断层片(Pa)。选取25例下颌不对称畸形患者的PAC和Pa。分别测量颅骨标本实体、颅骨标本的PAC和Pa、以及患者的PAC和Pa中的髁突长、下颌升支长和下颌体长。对颅骨标本测量项目的实际值和相应的影像测量值进行相关性检验,比较25例患者PAC和Pa的相应测量值的差异指数,用图表观察不同测量者测量同一样本所得测量结果的离散度。结果:当颅骨标本有钢珠标志时,其大部分影像测量值与实际值显示很强的相关性(0.96～0.99,P<0.01)。当颅骨标本无钢珠标志时,Pa测量的髁突长和下颌升支长与实际值有很强的相关性,PAC所测下颌升支长和下颌体长与实际值的相关性降低,髁突长无法测量。不同测量者测量下颌升支长时,在Pa所测的可重复性要比在PAC所测者高,测量下颌体长时,在PAC所测的可重复性则比在Pa高。结论:PAC对评价下颌骨水平向不对称较有价值,对评价下颌骨垂直向不对称的作用有限;Pa对评价下颌骨水平向不对称的价值不高,但对评价下颌骨垂直向不对称有确切的意义。     

Fetal cleft lip repair in rabbits: postnatal facial growth after repair

We have previously described a model for in utero cleft lip repair in rabbits. Cleft lip and alveolus (CL) were created in fetal rabbits at 24 days gestation (term, 31 days). In this study, postnatal maxillary growth was evaluated in three groups of animals: 1) unoperated controls, 2) unrepaired CL, and 2) repaired CL. The animals were killed at 4, 12, and 26 weeks after birth. Direct cephalometry was performed on dry skulls to evaluate premaxillary width, anterior maxillary length and width, and posterior maxillary width. The results of this study indicate that rabbits that undergo an in utero CL procedure, with or without repair, exhibit no significant decrease in maxillary length and width when compared with controls.     

Secular Changes in the Morphology of the Skull in Swedish Men

Three hundred and twelve Swedish inductees (average age 18.7 years) were compared with skulls from men aged 18–25 who had died in 1810 regarding skull morphology and the dimensions of the dental arches.

The skull morphology was analysed roentgen-cephalornetrically with profile and postero-anterior roentgenograms. the sizes of the dental arches were measured on casts and directly on the skulls.

The cranium was found to be larger in the inductees than in the skull material. the cranial base was more cnrved in the inductees, which also showed more maxillary alveolar prognathism, proclination of the upper incisors and larger gonion angle. the width of the dental arches between the first molars was smaller in the present day material, while the length of the dental arches was longer.

The results show that parallel to the secular increase in body height there is also secularisation of the morphology of the cranium, including changes also in the cranial base, which suggests a change in the genetic constitution of the population in western Sweden during the last 160 years.     

Three-dimensional fetal cephalometry: an evaluation of the reliability of cephalometric measurements based on three-dimensional CT reconstructions and on dry skulls of sheep fetuses.

AIM: To develop a 3D CT cephalometric analysis for maxillary growth evaluation of sheep fetuses operated in utero, and to evaluate the reliability of this analysis by comparing it with a direct cephalometric analysis on dry skulls. MATERIAL AND METHODS: Five skulls of operated sheep fetuses were used, which after preparation were CT scanned and a 3D reconstruction was performed. A cephalometric analysis was performed directly on the dry skulls as well as on the reconstructed 3D CT images. In total, 56 linear distances were measured. In order to access the error of the method, the procedure was repeated after a 2 week interval. RESULTS: The comparison between the direct cephalometric and the 3D CT analysis revealed that only 5 variables were significantly different. The evaluation of the error of method revealed that 7 variables of the direct cephalometric analysis and none of the 3D CT analysis differed significantly. CONCLUSIONS: According to the results of this study, it can be concluded that a cephalometric analysis on 3D CT reconstructed images of the skulls includes fewer identification errors and seems to be an accurate and reliable method that could be regarded at least as equivalent to conventional cephalometry.     

Relation of the glenoid fossa to craniofacial morphology, studied on dry human skulls

The purpose of this work was to compare glenoid fossa dimensions and craniofacial morphology on the basis of standard lateral roentgenograms. To overcome the difficulties encountered in making exact measurements on living subjects, 59 dry skulls were used. Eight angular measurements were taken to describe the form of the skull base, mandible, and articulating surface of the glenoid fossa, four linear measurements to describe the position of the fossa, and one to describe the size of the whole skull. A close relationship was observed between the morphology of the articulating surface of the glenoid fossa and the mandibular morphology. The skull base angulation was associated with the position of glenoid fossa in two ways. Basically, the position of the fossa is related to skull base characteristics, but the location of the articular eminence in relation to the clival plane suggests that the mandibular condyle may cause a remodeling of the eminence anteriorly when the glenoid fossa otherwise is translocated posteriorly in association with the flat skull base.     

Vertical palatal bone dimensions on lateral cephalometry and cone-beam computed tomography: implications for palatal implant placement

Objectives: To evaluate the necessity of three‐dimensional imaging (computed tomography [CT]/cone‐beam computed tomography [CBCT]) for paramedian insertion of palatal implants. Material and methods: Lateral radiographs and CBCT scans were performed from 18 human skulls. For lateral cephalometry, the nasal floor (right/left) and the oral hard palate of all skulls were lined with a tin foil for contrast enhancement. The quantity of vertical bone as measured on lateral radiographs was compared with CBCT measurements obtained in median and parasagittal planes and at minimum bone height. Spearman's rank correlation coefficients were determined for bivariate correlation analysis. Results: The median palatal bone height on CBCT (mean 8.98 mm; standard deviation [SD] 3.4) was markedly higher than the vertical height seen on lateral radiographs (mean 6.6 mm; SD 3.2). Comparing lateral cephalometry with CBCT, the strongest association was observed at the minimum palatal bone height (r=0.926; P<0.001; Spearman's rank correlation coefficient). Conclusions: Lateral radiographs allow accurate and adequate assessment of vertical bone before paramedian insertion of palatal implants. The vertical bone dimension as displayed on lateral cephalometry reflects the minimum bone height rather than maximum bone in the median plane. Therefore, a preoperative CT or CBCT is only indicated when the lateral cephalometry reveals a marginal quantity of bone. To cite this article:
Jung BA, Wehrbein H, Heuser L, Kunkel M. Vertical palatal bone dimensions on lateral cephalometry and cone‐beam computed tomography: implications for palatal implant placement.
Clin. Oral Impl. Res. 22 , 2011; 664–668
doi: 10.1111/j.1600‐0501.2010.02021.x     

The accuracy of spiral tomography to assess bone quantity for the preoperative planning of implants in the posterior maxilla

When planning to place implants in the posterior region of the maxilla, the location of the maxillary sinus floor is influencing the available bone height and the implant length chosen. The aim of the present study was to evaluate in vitro the spiral tomographic technique that could be used for pre-operative implant planning. Tomographs were taken of 6 dry human skulls using the Cranex Tome multifunctional unit (Orion Corporation Soredex, Helsinki, Finland). Three sites were selected in the left posterior maxilla and marked with gutta percha meaning a total of 18 sites (6 x 3 = 18) for interpretation. Bone height and width were measured on the tomographs and after sectioning also on the skulls. The values obtained from the measurements on tomographs were divided by an enlargement factor of 1.5 (as defined by the manufacturer) and then compared with those from the real measurements on the skulls. Real measurements were on average 0.24 mm (SD 0.19) lower than the tomographic measurements (P < 0.05). From the present results it could be concluded that spiral tomography using the recently developed Cranex Tome reveals sufficient information and detail for pre-operative planning of a limited edentulous region.     

Trigonocephaly: clinical and cephalometric assessment of craniofacial morphology in operated and nontreated patients

Craniofacial parameters were studied clinically and by cephalometry in 11 trigonocephalic patients from infancy to 4 years of age. Six of the most severe patients had surgery between 6 and 18 months of age. Analysis of morphology indicated that bony interorbital distance was reduced in patients selected for surgery and hypotelorism persisted at final examination. All patients demonstrated orbital width measurements above the mean for the norm, while orbital height was essentially normal. All but one of the patients had a variably prominent forehead bony ridge that was eliminated or reduced as a result of surgery and/or growth. However, the forehead of most patients, whether operated or not, was too narrow when compared to normal skulls. Thus, although some of the striking features of trigonocephaly are eliminated, minor characteristics of the anomaly still persevere at 4 years of age.     

Alveolar bone anatomic profiles as measured from dry skulls

Abstract The purpose of this study was to evaluate the relationship of alveolar bone morphology to tooth shape and form. 111 dry skulls were evaluated at Baylor College of Dentistry (Dallas, Texas). The skulls were arbitrarily divided into flat, scalloped and pronounced scalloped anatomic profiles according to alveolar bone anatomy. The number of buccal dehiscences and fenestrations was determined for each skull according to their anatomic morphotype. 10 skulls from each group were selected for bone height measurements. The measurements were made with a periodontal probe and ruler from the height of the interproximal bone to the buccal alveolar crest. Kodachrome slides were used to measure mesial-distal tooth width and length from ten skulls from each anatomic category. The average number of fenestrations for each group was 3.5. The mean number of dehiscences for flat and scalloped skulls was 0.5. The average number of dehiscences for pronounced scalloped was 1.2. There were no significant differences when the groups were compared. The mean distance from the height of the interdental bone to the alveolar crest was statistically significant when the groups were compared (flat 2.1 mm, scalloped 2.8 mm. pronounced 4.1mm) (Tukey, p=0.05). There were no significant differences when tooth shapes were compared with bone anatomy. Pronounced scalloped anatomic profiles were slightly narrower when compared with the other groups. The observations reported have treatment ramifications when patients with scalloped or pronounced scalloped morphotypes are being considered for dental implant placement.     

The reproducibility of cephalometric landmarks: an experimental study on skulls

Few previous cephalometric studies have used dry skulls in order to eliminate the effects of the facial soft tissues. The aim of this study were to quantify the intra-examiner reproducibility of the commonly used cephalometric landmarks, angles and distances, using dry skulls and to compare these errors with previous error data obtained from normal cephalograms of living patients. Thirty skulls were mounted in a purpose-designed holder and repeat cephalograms of each skull were recorded and digitised. All measurements were made relative to an X-Y coordinate reference grid. Scattergrams were produced to show the characteristic distribution of the intra-examiner reproducibility errors for the landmarks, and the reproducibility of the angles and distances were tabulated. This data was compared with a related study that included the soft tissue profile. The standard deviations of the skeletal and dental angles and distances were greater in the presence of the soft tissues. These differences were up to four times larger for measurements including the location of Nasion (e.g. SNA, SNB and SNPg), which was the landmark location most affected by the presence of soft tissues, and for the distance: Incisal tip of Lower Incisor to Pogonion. Anterior Nasal Spine, in the horizontal plane, was also greatly affected by the presence of the soft tissues. By using dry skulls, the errors observed in this study may serve as standards for the rational interpretation of clinical cephalometric values.     

Three-dimensional anatomic landmarks of the foramen magnum for the craniovertebral junction

The foramen magnum (FM) has a vital importance to have a direct view of the vertebral artery, lower cranial nerves, and the brainstem. The morphologic analysis of the FM was studied in 352 occipital bones of adult human skulls by 3D-Doctor V 3.5.050402 Demo version. The perimeter and area of the FM were calculated as 115.6 (SD, 9.9) mm and 829 (SD, 137.7) mm(2), respectively. The FM index was found as 84.02%, and the majority (38.4%) of holes were observed to have a narrow index.The FM was observed to 8 different types. The most frequently observed types were the tetragonal type in 25.66%, and the one formed by the combination of 2 semicircles in 23.28%. The large anterior margin of the FM type, such as types 1, 4, 5, and 6, can be easily performed partially. In the cases of types 2, 3, and 8, the anterior margin was determined as narrow, the resection procedure is completed with more difficulty. In Pearson correlation analysis, it is significant that a statistically strong relation was found between the area and perimeter, and the area and length of FM. This findings suggest that the resection should be started at the anterior margin, just lateral and then extended superolaterally.     

替牙期62例上颌尖牙阻生儿童牙弓及腭部形态特征分析

目的:比较上颌尖牙阻生与无阻生儿童牙弓及腭部形态的差异,为上颌尖牙阻生早期识别和干预提供参考.方法:选择8～11岁[平均(9.82±1.04)岁]儿童62例,分为实验组(上颌尖牙阻生)和对照组(无上颌尖牙阻生),每组31例.将2组患者石膏模型通过3D激光扫描后转化为数字模型,测量牙弓宽度、牙弓长度、基骨宽度、腭部宽度、...     

Asymmetry of the facial skeleton in Negroid skulls]

Measurements of 18 bilateral signs were carried out in 94 Negroid skulls. All parts of the facial skull are clearly asymmetrical, if regarded separately, while the summary sizes of the left and right halves of the facial skull are equal. In the upper part of the face the most asymmetrical parameters are the width of the bridge of the nose, width of the nose, and width of the palate, while the least asymmetrical are the height of the orbit and palate and length of the palate. In the mandibular part the greatest asymmetry was observed in the thickness and height of the mandibular corpus and height of the mandibular branches. The resultant combination of symmetry of the total sizes of both sides of the facial skull and asymmetry of individual parts is interpreted as an indication of the compensatory changeability of bilateral signs of the facial skull. The results are similar to data on the asymmetry of the facial skull of Mongoloid, Europeoid, and the intermediate skulls.     

Interrelationships of Brain,Cranial Base and Mandible

The purpose of this study is to evaluate the neural and masticatory growth factors that contribute to the development of the cranial base. Cephalometric and submentovertex (SMV) radiographs of 66 adult human skulls, of Caucasian (India) origin and unknown gender were used in this study. Results indicate that the cranial base, posterior to the foramen caecum, develops in response to brain growth. The part anterior to the foramen caecum develops in response to the mandible. Our findings indicate that: 1. the glabella instead of the nasion should be considered as the most anterior point of the cranial base. Mandibular dimensions (the height and the length) have a better correlation with CG than CN. 2. Instead of a single parameter, sella-nasion (SN), two parameters, the foramen caecum-glabella (CG) and the foramen caecum-sella (CS) should be considered. In cephalometry the more stable line CS, rather than SN, can be used for registration of successive radiographs; 3. The typical mandibular retrognathia, and/or the decrease in the posterior height (ascending ramus) of a Class II malocclusion could be explained by their positive correlation with SB (sella-basion) and the negative correlation with angle GSB.     

Interrelationships of brain, cranial base and mandible

The purpose of this study is to evaluate the neural and masticatory growth factors that contribute to the development of the cranial base. Cephalometric and submentovertex (SMV) radiographs of 66 adult human skulls, of Caucasian (India) origin and unknown gender were used in this study. Results indicate that the cranial base, posterior to the foramen caecum, develops in response to brain growth. The part anterior to the foramen caecum develops in response to the mandible. Our findings indicate that: 1. the glabella instead of the nasion should be considered as the most anterior point of the cranial base. Mandibular dimensions (the height and the length) have a better correlation with CG than CN. 2. Instead of a single parameter, sella-nasion (SN), two parameters, the foramen caecum-glabella (CG) and the foramen caecum-sella (CS) should be considered. In cephalometry the more stable line CS, rather than SN, can be used for registration of successive radiographs; 3. The typical mandibular retrognathia, and/or the decrease in the posterior height (ascending ramus) of a Class II malocclusion could be explained by their positive correlation with SB (sella-basion) and the negative correlation with angle GSB.     

Dimensional variation of craniofacial structures in relation to changing masticatory-functional demands.

A reduction in masticatory stress has been an important factor in the evolution of the human skull. Similarly, the recent increase in the occlusal variation has been related to a change in masticatory activity. The present study investigates short-term variation in craniofacial dimensions by examining cephalometrically two Finnish samples, one exposed to a hard and the other to a soft diet. The samples comprised 32 skulls, derived from the 16th and 17th centuries, and 50 living individuals. Out of 18 dimensions measured, 12 showed only non-significant differences between the samples. In the present-day sample, the cranial length and the anterior cranial base were significantly longer, and the upper incisors segment significantly higher. In the skull sample, the posterior facial height, the height of the mandibular ramus, and the antero-posterior width of the pharynx were significantly larger. The results suggest that hard diet, which requires more chewing force and time, promotes vertical growth of the ramus and anterior translocation of the maxilla. The greater posterior face height and greater height of ramus are in accordance with the earlier finding that the mandible shows more anterior growth rotation in an attritive environment. These findings support the hypothesis that the growth of the craniofacial skeleton is regulated by masticatory stress. It is suggested that both the dimensional changes and the lack of dental attrition may have contributed to the higher occlusal variation of modern individuals.     

Reference Values for Craniofacial Structures in Children 4 to 6 Years Old: Review of the Literature

This review article addresses the question as to what methods can be used to investigate cranial structure and growth development in children 4 to 6 years old, and what the relevant reference values are for this age group. We screened the literature for epidemiological, longitudinal and cross-sectional studies investigating healthy children 4 to 6 years old without abnormalities and orthodontic therapy. Radiographic cephalometry is a practical, valid tool for analyzing craniofacial structure and growth processes. But it has several disadvantages, including the use of ionizing radiation, measuring points that are difficult to locate, no means of radiographic enlargement without distorting reference values, and the data's two-dimensionality. Anthropometry is another procedure for creating reference values for the craniofacial structure in children. Its advantages over radiographic cephalometry include three-dimensional results and no radiation exposure. Moreover, it yields precise and valid results for a wide variety of potential applications.In addition to these procedures, there are other techniques with which cranial structure and growth development in children 4 to 6 years old can be investigated. Those reported in the literature in this connection include standardized photographs, the creation of computerized and magnetic resonance images, and investigations performed on dry skulls. In short, there is great demand nowadays for investigations aimed at developing reference values for Caucasian children 4 to 6 years old. Radiographic cephalometry and anthropometry are two very common methods. Anthropometry is expected to become increasingly important because it involves no exposure to radiation.     

曲断片磨牙段线性测量放大率的比较

目的比较曲断片各磨牙区域的横向放大率和纵向放大率,评价横向及纵向线距测量的精确性。方法选择六个磨牙段完全萌出的成人干颅,用直径0.75mm 的不锈钢珠在各磨牙的三个横向平面(牙(牙合)面、牙颈部、根尖部)进行磨牙区域间标记,并构成牙冠部和牙根部两个纵向平面。拍摄曲断片,计算各横向线距和纵向线距曲断片放大率,进行统计分析。结果个体间磨牙区域横向放大率和纵向放大率差异都有显著性(P<0.05)。个体内第一磨牙后的各磨牙区域横向线距放大率在同一横向平面内无显著性差异,在不同平面间差异有显著性,颈部比牙(牙合)面小。个体内同一纵向平面各纵向线距放大率在上颌牙冠部差异无显著性而在牙根部差异有显著性。在下颁牙冠和牙根部都有显著性差异(P<0.05),有随着磨牙位置的后移纵向放大率均值逐渐减小的趋势。上颌在不同纵向平面间放大率差异有显著性,下颌无显著性。结论曲断片测量牙弓后部线距,个体之间无论横向还是纵向线距测量都没有可比性。个体内横向线距在同一平面第一磨牙之后的磨牙区域具有可比性。     

Cephalometric and physiologic predictors of the efficacy of an adjustable oral appliance for treating obstructive sleep apnea

The purpose of this study was to investigate whether any physiologic or cephalometric parameters could be used to predict the efficacy of an adjustable mandibular advancement appliance for treating obstructive sleep apnea (OSA). Forty-two male and 5 female patients with OSA were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) greater than 15 per hour. Repeat polysomnography was performed with the appliance in place. Baseline cephalometry was performed for each patient, and follow-up cephalometry was completed for 19 of the subjects. The subjects were divided into 3 groups on the basis of the degree of change in the AHI with oral appliance therapy: good response (> 75% decrease in AHI), moderate response (25% to 75% decrease in AHI), and poor response (< 25% decrease in AHI). Patients with a good response were younger and had smaller upper airways. In a linear regression analysis, the change in AHI (%) was associated with physiologic (age and body mass index), cephalometric (overjet, height of the maxillary molars, vertical height of the hyoid bone), and airway variables. However, changes in either overbite or overjet were not related to changes in any of the polysomnographic variables for the 19 subjects. A stepwise regression analysis revealed a better treatment response with the adjustable mandibular advancement appliance in patients who were younger and had a lower body mass index, a longer maxilla, a smaller oropharynx, a smaller overjet, less erupted maxillary molars, and a larger ratio of vertical airway length to the cross-sectional area of the soft palate.