附着体应用于单侧上颌骨缺损修复的三维有限元分析

目的:对附着体应用于单侧上颌骨缺损修复进行三维有限元力学分析。方法:利用已有的单侧上颌骨缺损的三维有限元模型,在ANSYS程序中分别设计并建立附着体支架,修复两种不同上颌骨缺损情况的模型(附着体位于中切牙或尖牙近中面),进行三维有限元力学分析。结果:应力集中区均位于健侧腭部基托的近前牙区,健侧后牙受力均匀;附着体位于中切牙近中时,中切牙近中面应力值为1.306MPa,附着体与舌面导板的连接处应力较集中;附着体位于尖牙近中时,尖牙近中面应力值为0.797MPa,应力集中区位于舌面导板的前下方转角区。结论:附着体应用于单侧上颌骨缺损修复,符合生物力学要求,未增加基牙的负荷。对附着体支架的设计,应作进一步研究。     

Bone graft healing in alveolar osteoplasty in patients with unilateral lip, alveolar process, and palate clefts

Secondary osteoplasty by means of autogenic spongy bone grafting is the most common procedure used in the reconstruction of the continuity of the maxillary alveolar process. The aim of the study was to analyze retrospectively the effect of certain factors on the course of the bone graft healing process in patients with unilateral complete clefts of the lip, alveolar process, and palate. The investigations involved 62 children aged 8 to 14 years (mean age, 11 years) with unilateral complete cleft of the lip, alveolar process, and palate operated on at the Clinic of Plastic Surgery in Polanica Zdrój from November 2007 to April 2009. All the procedures consisted in the reconstruction of the maxillary alveolar process by means of autogenic spongy bone grafting from the iliac bone. The analysis was performed on the basis of computed tomography scans presenting maxillary alveolar processes in the horizontal cross-sectional planes performed on the second or third postoperative day and after 6 months. They were used as the basis for the measurement of the volume and density (condensation) of the bone graft, the surface of its adhesion to the maxillary alveolar bone, and the volume and density of the healed bone. The following correlation coefficients were determined: between the adhesion surface of the bone to the alveolar bone and the volume of the healed bone, between the adhesion surface of the bone to the alveolar bone and the density of the healed bone, and between the density of the graft and the volume of the healed bone. Increasing the surface of the graft adhesion to the bone ridges of the alveolar cleft contributes to increased volume of the healed bone and slows down the increase in its density (on 6-month follow-up). Crushing of the bone graft increases its resorption and reduces volume of the healed bone.     

Spee曲线深度与牙弓形态之间的关系研究

目的 研究Spee曲线深度与牙弓形态之间的关系。 方法 将150例18-25岁的维吾尔族人分为男女两组,其中男62人,女88人,利用计算机软件测量Spee曲线深度,尖牙间宽度,磨牙间宽度,牙弓长度。结果 Spee曲线深度与性别因素无关,左右侧Spee曲线深度存在统计学意义,牙弓形态受性别因素影响,却与Spee曲线深度不存在关联。结论 临床上,Spee曲线深度可当一个参考平面辅助咬合重建以及正畸治疗。     

Frontal cephalometric evaluation of transverse dentofacial morphology and growth of children with isolated cleft palate

The transverse dentofacial morphology and growth of 64 children operated on for clefting of the hard and soft palate was studied by means of a frontal proportional cephalometric analysis and was compared to a normal sample at the ages 3-4, 8-9 and 12 years. The cross-sectional comparison of the cleft palate and normal samples at the three periods indicated: (a) The presence in the cleft group of significantly increased ratios of the inner orbital width to the interorbital width and of the width of the nasal cavity to the interorbital width; (b) the absence of any significant differences in the ratio of the maxillary intermolar width to the interorbital width; and (c) the presence of almost identical ratios of the intergonial width of the mandible to the interorbital width and of the width of the maxilla to the intergonial width of the mandible. Evaluation of the changes of all cephalometric variables during the period 8-12 years showed the absence of any significant difference between the cleft palate and normal groups.     

The biomechanical relationship between incisor and condylar guidances in deep bite and normal cases

The purpose of this study was to investigate the biomechanical relationship between the condylar and anterior guidances in deep bite malocclusion and control groups. The subjects consisted of 18 deep bite patients and 14 normal occlusions. A four-bar mechanism was described on the lateral cephalogram films and a computer program, for which the lengths of the links measured on the films were the inputs, was developed. The computer program was used to calculate the angles of rotation of the mandible and the condyle during contact of the mandibular anterior teeth with the lingual surface of the maxillary anterior teeth as the mandible moves forward. Comparison of the mean values of the angles of rotation of the mandible and condyle in the two groups has shown that the change in the angle of rotation of the condyle is statistically significant (P < 0.05). The angles of rotation of condyle in deep bite group were found larger than the angles of normal group. Correlation between the angles of rotation of the condyle and mandible has shown that they were significantly related. The cause of temporomandibular disorders may be attributed to the large angle of rotation of the condyle in deep incisal overbite.     

Orthopedic effect of the extraoral chin cup appliance on the mandible.

An anatomic photoelastic model of a human skull was constructed with the use of individual simulants for teeth, bone, and periodontal ligaments. The following effects of extraoral chin cup traction were observed: 1. Stresses were noted in the area of the pterygoid plates of the sphenoid bone due to the insertion of the simulated external pterygoid muscle. 2. Because of direct contact of the condyle against the posterior surface of the glenoid fossa, forces were seen to be transmitted to this anatomic area. 3. Stress trajectories followed the trabecular pattern of the anatomic configuration of the mandible. 4. Beginning at the apices of the incisor teeth, the stresses emanated through the body, the angle and retromolar triangle of the mandible, radiating in a posterosuperior fashion and concentrating at the neck of the condyle. 5. Selected sectioning of the mandibular model showed evidence of stress concentration at the lingual aspect of the angle and retromolar area as well as at the condylar neck at the level of the external pterygoid muscle insertion. The effects of orthopedic forces produced by an extraoral chin cup in this study are correlated with the histologic and clinical observations during the utilization of this appliance in the treatment of Class III malocclusion.     

Anatomosurgical study of the marginal mandibular branch of the facial nerve for submandibular surgical approach

The purpose of this study was to estimate the distance from the mandibular marginal branch of the facial nerve to the inferior margin of the mandible in order to determine the best and safest location to approach the posterior mandibular region. Forty-five hemi-faces of 27 Brazilian adult cadavers were dissected and the distance between the mandibular marginal branch and the inferior margin of the mandible was measured. The number of marginal branches and anastomoses with other branches of the facial nerve was also recorded. The evaluation of the anatomic pieces showed 1 to 3 branches of the marginal mandibular branch, anastomoses with the buccal and cervical branches of the facial nerve and distances between 1.3 cm to +1.2 cm from the inferior margin of the mandible. In 57.7% of the cases, the nerve passed superiorly and along the length of the inferior margin of the mandible. Based on the findings of the present anatomosurgical study, it may be recommended an incision 3 cm below the inferior margin of the mandible associated to a careful dissection in planes and flap retraction. This is expected to reduce the risk of neuropraxia of the marginal mandibular nerve making the submandibular incision a safe approach.     

Position of teeth on the edentulous atrophic maxilla

For prosthetic treatment of strongly atrophic alveolar wall, some biometric methods have been developed. The measurements taken from plaster cast models of 230 edentulous, average 29.9 years, and 125 dentulous post-menopausal women were correlated. In the edentulous maxilla the sagittal position of canine teeth can be determined by the oral edge of incisive papilla. The transverse position of canine teeth was on the outer edge of the alveolar wall because of the extensive loss of buccal alveolar bone. On the incisor area the facial surfaces of the central incisors were determined by the oral edge of incisive papilla and the distance was about twice the length of the papilla. The sagittal position of the first premolars was one-third and the first molars two-thirds the length of the palate from the plane of the labial edge of incisive papilla. The transverse position of the premolars and molars was determined by the scar-line, which is a cord-like elevation or track on the alveolar mucosa after extractions of the teeth. According to the comparative method, the position of the scar-line differed from the lingual gingival margin line and was situated about half breadth of the tooth in a buccal direction from it. The transverse position of premolar and molar in the edentulous maxilla is about the middle of the scar-line in a facio-buccal direction. In the setting of the artificial teeth, the facial surfaces of these teeth should be on average 5.0-6.0 mm sideways from the scar-line, whilst the total bilateral breadth of the alveolar wall in the sulcus area was on average 1.0-2.0 mm larger.     

Experimental evaluation of initial tooth displacement, center of resistance, and center of rotation under the influence of an orthodontic force.

The purpose of this study was to determine the location of the center of resistance and the center of rotation of the maxillary central incisors under the influence of a single simple force and to investigate related geometric parameters of the teeth and the surrounding periodontal tissues. By measuring the initial displacement of the central incisors with a magnetic sensing system, the location of the center of resistance and the centers of rotation associated with various forces were determined in 3 human subjects. The results show that the location of the center of resistance of the maxillary central incisor depends on the palatal bone level and is at approximately two-thirds of the palatal alveolar bone height, measured from the root apex. A greater moment-to-force ratio is needed for any controlled movement of the maxillary incisors during retraction in patients with reduced palatal alveolar bone height. This study suggests a method for estimating the location of the center of resistance of a tooth.     

Healing mechanism of tooth extraction wounds in rats—I Initial cellular response to tooth extraction in rats studied with H-thymidine

An autoradiographic study with ³H-thymidine was made of the early stages of the healing process following the extraction of the upper first molars in 12 male rats.

An initial proliferative response to tooth extraction was observed in the remaining periodontium of the socket, fibroblasts and endothelial cells of the gingiva at the edge of the wound, and the periosteum of the buccal alveolar bone.

The percentage of labelled cells was recorded in the fundus of the socket, the fibrous tissue of the palatal gingiva at the edge of wound and the periosteum of the buccal alveolar bone associated with new bone apposition. Granulation tissue filled the socket by 3–4 days after tooth extraction and the 3-day wound showed the highest percentage of labelled cells in the fundus of the socket.

Uptake of ³H-thymidine in the fibrous region of the gingiva at the edge of wound reached its peak at 4 days after tooth extraction. The maximum increase of labelled cells in the periosteum outside the socket was noted at 1 day after tooth extraction.     

Response properties of single sensory units innervating human temporomandibular joint

The purpose of this study was to examine the response patterns of single sensory units innervating the human temporomandibular joint to the displacements of the mandibular head. 13 single sensory units were recorded from the auriculotemporal nerves of five adult subjects by the method of microneurography and the response patterns were analyzed. The results obtained were as follows: (1) The response patterns of the same unit to the directions of the mandibular movements were classified as Slowly Adapting Type and Fast Adapting Type according to the characteristics of their adaptation. (2) The threshold value of the Fast Adapting Type was higher than that of the Slowly Adapting Type. (3) Increasing the rate of the mandibular opening movements in the initial stage, the firing frequency of the units increased in the response pattern of the Slowly Adapting Type. It was concluded that the sensation in the directions of the displacements of the mandibular head can be induced by the response patterns of the impulses in the nerve fibers innervating the temporomandibular joint.     

下颌前伸时颞下颌关节应力分布的三维有限元研究

目的探讨下颌前伸运动时颞下颌关节内的应力分布情况。方法利用可视化人体图像建立包括上下牙列、下颌骨、颞下颌关节在内的三维有限元模型,在Patran中采用位移加载的方法模拟下颌前伸运动至对刃位,在Marc中计算并分析接触情况和应力分布特性。结果关节盘随髁突向前、下运动,髁突的前斜面首先与关节盘中间带中央部发生接触,随后髁突的外斜面与关节盘的中间带外侧部、关节窝的顶部与关节盘的后带发生接触。关节盘的中间带外侧部(3.10 Mpa)和髁突的前斜面(5.05 Mpa)等部位的应力值较大。结论在前伸运动时,应力集中区位于关节盘的中间带外侧部和髁突的前斜面。     

The remodeling of the edentulous mandible

In a sample of mandibles having complete or nearly complete loss of dentition, the left half of each mandible was serially sectioned. The entire perimeter of each section was analyzed for the distribution of resorptive and depository periosteal surfaces, and from this information, the fields of remodeling were mapped for the mandible as a whole. The most common patterns of combined resorption-deposition and the range of variations were then determined. The over-all distribution of remodeling fields in the edentulous mandible differs markedly from that in the young, growing mandible. In most of the edentulous specimens, the surface of the basal bone on both the medial and lateral sides of the corpus is of a depository nature. The overlying alveolar regions on both the lingual and buccal sides, however, are characteristically resorptive. Significantly, the placement of the reversal line between the alveolar resorptive and the basal depository areas is much lower (i.e., at the level of the mental foramen) on the buccal side. Except for its inferior part, the lateral side of the ramus tends to be largely resorptive in character, and the posterior half of the lingual side also tends to be resorptive. Unlike the child's mandible, the posterior border of the ramus is resorptive, and the posteroanterior dimension of the ramus (not the whole mandible) becomes reduced and narrowed in conjunction with resorption along the anterior border. However, the amount removed from the anterior ramus is actually added to the dimension of the corpus, which becomes longer. Further, removal from the posterior ramus border does not affect the over-all length of the mandible unless condylar reduction is also involved. Also, over-all arch length is not decreased, because the surface of the mental protuberance is retained as a depository type of field (or at least does not become actively resorptive). The corpus-ramus angle (not gonial angle) is increased in the antegonial region. Because of the opening of this angle, over-all mandibular length as well as arch length is increased. In about half of the specimens, arch width was not decreased, because the lateral side of the corpus is usually of a depository nature. Notching of the anterior side of the condylar neck and the inferior part of the anterior ramus border is associated with resorptive fields in these regions, changes that are presumed to be a consequence of pressure contacts made with the articular tubercle and the maxillary tuberosity, respectively, in conjunction with a forward rotation of the whole mandible. The inferior direction of corpus realignment relative to the basal part of the ramus also increases the notching effect in the antegonial region, an effect augmented by the presence of the resorptive field in the notch itself. Certain specific variations commonly occur in several major regions of the mandible on both the lateral and medial sides...     

影响托槽脱落的相关因素研究(二)

目的：探讨口腔固定矫治技术中影响托槽脱落的相关因素。方法：选取固定矫治技术的口腔正畸患者298例,男111例,女186例,粘贴托槽5258个,记录托槽脱落情况,并对此进行研究。结果：经过统计学分析,托槽的脱落率：①在粘贴托槽后第1个月脱落率最高,而后开始下降,从第5个月起进入相对稳定状态。②上颌与下颌之间,切牙没有差异,上颌尖牙小于下颌尖牙,上颌前磨牙大于下颌前磨牙。但总体上上颌与下颌间没有显著性差异。③左侧与右侧没有显著性差异。④前牙明显小于前磨牙。⑤上颌牙中,第二前磨牙脱落率最高,第一前磨牙次之,切牙再次之,尖牙最低;下颌牙中,第二前磨牙脱落率最高,其余牙相近;所有牙齿中,第二前磨牙最高,尖牙最低。结论：托槽的脱落率与多种因素有关,临床上必须了解和重视这些因素,从而减少托槽的脱落,提高矫治质量。     

Quantitative analysis of connective tissue resorption in the supra-alveolar region of the mouse incisor ligament

During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in the occlusal direction and is degraded in the supra-alveolar region.
In the present study stereologic analysis at the ultrastructural level has shown that significant reduction of the amount of extracellular collagen is confined to the most occlusal region of the ligament, just apically to the functional epithelium. In connection herewith a relatively high amount of homogeneous material of moderate electron density was found in the intercellular space, suggesting a process of extracellular collagen breakdown near the epithelium-connective tissue interface.
With respect to the distribution of collagen phagocytosis by fibroblasts, it appeared that the volume density of cytoplasmic vacuoles containing collagen fibrils was considerably higher in the supra-alveolar region of the ligament than in its subcrestal part, particularly in the zone along the tooth surface. This phenomenon is interpreted as being indicative of increased phagocytic activity of fibroblasts leading to the detachment of the periodontal ligament from the cemeatum before it enters the region of final degradation near the apical termination of the junctional epithelium.
In an attempt to identify the cells involved in the degradation of (fragments of) periodontal fibroblasts in the supra-alveolar region, periodontal ligament cells were labelled with tritiated thymidine at their site of origin. By means of both autoradiography and electron microscopy, it was shown that, following the arrival of Jabelled fibroblasts in the supra-alveolar region, at least part of the degradation of cellular constituents is accomplished via a process of heterophagocytosis among fibroblasts.     

Influence of direct prostheses on the condition of the alveolar processes during dental implantation

ObjectiveThe purpose of this article is to study of the processes accompanying osseointegration of the dental implants using various plate prostheses as temporary constructions, as well as to compare the dynamics of changes in the state of the jaw alveolar processes.Materials and methodsThe effect of dentures on the condition of the alveolar processes was studied in all patients according to the technique developed by L. Chulak on the 7th, 14th, 30th day and in 3, 6 months. To verify the results, the degree of atrophy of the alveolar processes was also determined by the second method the authors have chosen at the same time as indicated above.ResultsThe measurement results confirm linear changes in the height of the alveolar processes of the jaws with a decrease in the tissues of the prosthetic area. Throughout the duration of the examination, atrophy of the tissues of the alveolar processes is observed. Judging by the results obtained during the patients’ study, it can be concluded that when applied as a temporary prosthesis with a dental delayed implantation of a partial denture made of polypropylene, the results of the state of the hard tissues of the mandible alveolar process show a better adaptation of the mucous membrane and slowing of atrophy of the jaw alveolar processes with this type of prosthetics.     

The progression of gingivitis to periodontitis in the beagle dog: a histological and morphometric investigation.

The spread of the inflammatory cell infiltrate in the progression of gingivitis to periodontitis in the Beagle dog follows the course of blood vessels. Buccolingually this is towards the periosteal surface of the bone and interdentally towards the midpoint and angles of the interdental septum. Interdentally the path of spread may be modified by the local anatomy. Bone resoprtion buccolingually progresses from the periosteal surface towards the tooth and interproximally along the crest of the interdental septa and within marrow spaces. The pathway of spread of the inflammatory cell infiltrate, the anatomic relationships of the teeth to each other and the original morphology of the alveolar bone may influence the pattern of bone loss in periodontitis.     

Articulatory function in glossectomized patients with immediate reconstruction using a free jejunum flap.

Postoperative articulation in 18 glossectomized patients was investigated. The subjects were: 5 cases of tongue tumour, 7 cases of tumour of the anterior part of the floor of the mouth and 6 cases of tumour of the lateral part. A new modification of the Freiburger test for speech audiometry was used as test material. Then the articulatory function was assessed according to an overall score based on 180 monosyllables, the manner of production of 171 initial consonants and the place of production of 85 glossal sounds. The cases of tumour of the tongue and the lateral part of the floor of the mouth had excellent scores in all classes of sounds, which were compatible with the normative data. The subjects of tumour of the anterior part of the floor of the mouth had low overall scores, low scores for plosive and affricative sounds, and very low scores for sounds produced with the rear of the tongue. The relation between the site or amount of resection and subsequent articulation was significantly poor in all categories of sounds for the cases of anterior tumour, particularly in the movement of the posterior portion of the tongue even though it was not involved in the operation. In all groups there was a weak negative relation between the amount of resection and postoperative articulation. In reviewing the literature, reconstruction with a free jejunum flap was considered to lead to better articulation than reconstruction by other techniques. The need to assess postoperative function objectively was stressed, to compare the postoperative functions and to determine the indications for the reconstructive technique.