CT辅助咽后壁瓣手术设计

目的 建立CT辅助设计咽后壁瓣的方法,以提高治疗效果。方法 应用CT测量26例腭咽闭合不全者在静止和发“i”时腭咽腔的宽度和长度,观察分析咽后壁瓣成形术所需的宽度、长度和咽后壁瓣蒂的位置和与软腭的附着位置。结果 静止时腭咽腔的宽度15.10-37.25mm,平均27.01mm,长度12.54-30.39mm,平均22.10mm;发“i”时腭咽腔的宽度为9.11-34.06mm,平均17.69mm;咽后壁瓣蒂的位置都在第一颈椎平面或以上;与软腭的附着位置大部分在软腭的中后1/3处。结论 CT作为一种定量评价腭咽闭合功能的方法,能够辅助设计咽后壁瓣手术方法。     

应用植入控释系统进行一次法根管治疗术的动物实验研究

目的：利用自制含氯霉素、甲硝唑等药物的控释系统，对实验家兔的血药浓度、药物抗菌活性和家兔根管、尖周组织的病理观察，为今后临床应用提供理论和实验依据。方法：应用组织病理观察和液相色谱分析技术。结果：用ＨＰＬＣ法得出实验用家兔血药浓度和抗菌活性均为阴性，根管及尖周组织病理切片无特殊表现。结论：自制控释系统是一种无毒、无副作用、有效的根管治疗药物剂型，可进行临床应用。     

Identification of a C-shaped canal system in mandibular second molars-part II: the effect of bone image superimposition and intraradicular contrast medium on radiograph interpretation

The purpose of this study was to investigate the effect of image superimposition from surrounding alveolar bone and intraradicular contrast medium on radiographic interpretation of a C-shaped canal system in mandibular second molars. Thirty mandibular second molars with fused roots were collected and stored in 10% formalin solution. After being scanned by microcomputed tomography and reconstructed, the buccal-lingual radiographs of each tooth were taken with or without intraradicular contrast medium and mandibular bony plates. The number of mesial and distal canals in the coronal-to-middle canal portion and the canal number in the apical 4-mm area were recorded. The buccal-lingual and three-dimensional view of reconstructed canal images were used to evaluate the accuracy of radiograph reading. The results were subjected to the Friedman and chi-square test. The results showed that without intraradicular contrast medium, the bone superimposition could decrease the accuracy of canal recognition significantly (p < 0.001), especially in the apical area. When contrast medium was in canals, the canal reading seemed not to be affected by the bone superimposition (p > 0.05). Based on these findings, the intraradicular contrast medium could increase the accuracy of canal recognition of a C-shaped canal system in mandibular second molars despite the bone image superimposition, especially in the detection of continuous C-shaped canals and the canals in the apical area.     

Heterotrophic ossification on a skin graft in a postburn scar of the chin

Some patients who have heterotrophic ossification (HO) in a postburn scar are occasionally seen in the clinic. The occurrence of HO following hip and abdominal surgery is common in males, whereas females are frequently affected following burns. The HO of skin grafts in burn scars of the superior body parts is uncommon, especially on the face. We report a recent case of a male patient in whom HO arose on skin grafts on his chin. The patient presented with a history of a painless chin mass for 48 years. Computed tomography scan suggested that the mass was located within subcutaneous tissue away from the lower jaw. The density of the mass was almost the same as the cortical bone of the lower jaw. The mass was completely resected under general anesthesia. It was a rectangular mass of 3× 0.5× 0.3 cm. Histological examination gave the diagnosis of HO, which was also confirmed by immunohistochemical stainings for vimentin. Recurrence was not found in this case by clinical and radiologic follow-up at 1 year after surgery.     

Placement and replacement of restorations in general dental practice in Iceland

Ninety-one Icelandic practicing dentists (51% response rate) provided information related to the reasons for placement and replacement of 8,395 restorations and 741 sealants in 5,997 patients. Information included the patient's gender and age, the clinician's gender and experience in years since graduation, the defined criteria for replacement of restorations, the estimated past use of material in five-year increments and the records of 100 consecutively placed restorations. The materials used include composite (52.7%), amalgam (29.2%), glass ionomer (9.5%), resin-modified glass ionomer (7.1%) and other materials (1.4%). Although material selection was independent of the clinician's gender, female patients received more composite and fewer amalgam restorations than their male counterparts. Reasons for placing restorations comprised replacement of failed restorations (47.2%), primary caries (45.3%) and non-carious defects (7.5%). Secondary caries was the main reason for replacement for all types of restorations. Chi square analysis related to the dependence between the reasons for replacement and clinician's experience showed that more experienced clinicians recorded a lower frequency of secondary caries than less experienced ones (p<0.0001), while the diagnoses of discoloration and fracture of restorations increased with the clinicians' experience (p<0.0001).     

不同年龄组和病损牙氟磷含量比的变化

随机采集口腔科门诊拔牙患者的离体牙７０个，按年龄分３组（儿童组、中青年组、老年组）；按病变分３组（正常组、龋齿组、氟斑牙组）。各组牙齿均经１０％甲醛浸泡。清除结石，用优级纯硝酸冷消化处理后，分别采用电化学分析法和分光光度法测定离体牙氟和磷的含量并计算氟磷含量比（Ｆ／Ｐ）。结果表明，中青年组Ｆ／Ｐ值是儿童组的１１８倍，是老年组的１．８倍；而正常组牙齿Ｆ／Ｐ值则是龋齿组的１．６倍，氟斑牙组的１．１倍。     

颌面部巨大血管畸形的放射治疗

目的 分析颌面部巨大血管畸形的临床特点及治疗方法,探讨放疗在血管畸形治疗中的可行性.方法 回顾分析2000年1月至2008年1月浙江大学医学院附属第二医院施行三维立体定向适形放射治疗的颌面部巨大血管畸形6例的临床资料,并主要根据影像检查与临床体检结果判断疗效.结果 6例患者在术中、术后无严重并发症,均对治疗后面部外形满意,MRI示病变范围缩小,甚至消失.随访0.5～9年,6例患者均无明显复发迹象.无一例出现视器损伤、张口受限等放疗并发症.结论 三维立体定向适形放疗可以作为一种安全有效治疗颌面部巨大血管畸形的方法.

Abstract：

Objective To discuss the clinical use of radiotherapy in the treatment of giant vascular malformation. Methods Six patients with giant vascular malformation in oral and maxillofacial region were treated by three dimensional radiation therapy in Department of Stomatology, The Second Affiliated Hospital,School of Medicne, Zhejiang University in the last ten years and the cilinical data were reviewed. The treatment results were evaluated by clinical examination and radiology. Results No complication was observed during and after the radiotherapy. All patients were satisfied with the aesthetic results. The lesions in MRI were all reduced and even disappeared. There was no sign of recurrence during the follow-up period.Conclusions Three dimensional radiotherapy is safe and effective for oral and maxillofical vascular malformation.     

Mechanical behavior of ProTaper universal F2 finishing file under various curvature conditions: a finite element analysis study

Introduction

The purpose of this study was to visualize the stresses and strain distribution patterns in ProTaper Universal F2 files (Dentsply Maillefer, Ballaigues, Switzerland) and to establish the stress- and strain-curvature relationship for this instrument under various conditions by using a dynamic, three-dimensional finite-element model.

Methods

An accurate geometric model of a ProTaper Universal F2 instrument was created. Two short, straight tubes were also modeled to represent the parts of root canal apical and coronal to the curvature. Then, the file was constrained to a curve of varying degree, curve length, and position. The maximum von Mises stress and strain on the tension side of the instrument was measured at 5-degree intervals in a numerical simulation package (LS-DYNA; Livermore Software Technology, Livermore, CA).

Results

The mechanical performance of the ProTaper F2 file under various conditions was simulated. A long curvature length produced lower values of stress and strain under the same angle of curvature. An increase in the curvature angle generally induces higher stress and strain. For the same degree and curve length, the stress and strain increased if the curved portion was situated further up the shaft of the instrument (ie, with a larger diameter).

Conclusions

The dynamic, numerical model may be used to evaluate and compare the effect of various root canal curvatures on the behavior of different designs of root canal instrument. The magnitude of stress and strain imposed on the instrument is influenced by the abruptness and degree of curvature as well as the location of the curved portion.