A new classification for crown fractures of teeth

The aim of this work is to define a classification for traumatic injuries to crowns of teeth that offers a simplified interpretation, which can be communicated easily. These data will help us to evaluate the future restorations (composite resins, crowns, porcelain veneers) according to the variable design and extension of initial crown fracture lines. For this reason we conducted research on a vast sample of subjects, who presented different traumatic lesions, in order to obtain a specific selection of these typologies of injuries. We reviewed the literature for a complete, brief classification of simple use, which could serve our cause. The traditional classifications (Andreasen, Ellis, OMS) did not satisfy us for different reasons. In fact, they only consider the initial lesion situation, never focusing on the shape of the lesion and therefore never giving suggestions for the best kind of material for restoration. On the contrary, our interest is to define the kind of more valid materials according to the variable design of crown fracture lines, to foresee the duration of these materials and the best time to substitute them. To simplify and make our research a more affordable one, we created a 4 classes classification (A-B-C-D) and 3 subclasses (b1-c1-d1). Class A: all the simple enamel lesions which involve a mesial or distal crown angle, or only the incisal edge; Class B: all the enamel-dentin lesions, which involve a mesial or distal crown angle and the incisal edge. When a pulpal exposure exists we define it a Subclass b1; Class C: all the enamel-dentin lesions, which involve the incisal edge and at least a third of the crown surface. When a pulp exposure exists we define it a Subclass c1. Class D: all the enamel-dentin lesions, which involve a mesial or distal crown angle and the incisal or palatal surface, with root cement involvement (crown-root fractures). When a pulpal exposure exists we define it a Subclass d1. This classification showed how different kinds of lesions (Class B, b1, C and c1, in our new classification) fall under the same definition (enamel-dentinal fractures) in traditional classifications (Andreasen, Ellis). However, they need a wholly different clinical approach, and the material involved in the treatment shows different behavior and duration. This new classification simplified the gathering of data and the communication among practitioners, thus confirming its importance in getting optimal diagnostic and therapeutic protocols. It also allowed us to identify the most frequent crown fractures (Class B, b1 and C, c1) that in our sample of patients (age range: 8-18) are typically treated with composite resins or original fragment reattachment technique. All these studies brought us to develop this new "easy to use" classification of dental crown lesions that helped us to gather data easily, to choose the right materials to improve the communication among practitioners including by electronic means,     

重建邻接面紧密度预防垂直型食物嵌塞的探讨

目的：探讨临床固定修复中冠与邻牙最适的接触紧密度,防止冠与邻牙之间垂直型食物嵌塞。方法：三个临床客观指征：就位完全,咬合完全,冠对邻牙有一定挤压感的方法,判断粘固前修复体与邻牙达到了最适合的紧密邻接关系,复查观察了冠与邻牙相邻接触面1400个。结果：均无食物嵌塞,成功率100％。结论：为临床修复体粘固前就能预防食物嵌塞,重建两者接触区正常的位置和良好的接触关系提供了一条新的方法。     

Amalgam crown restorations for posterior pulpless teeth

Cast restorations are the usual technique chosen for the restoration of posterior pulpless teeth. Complex amalgam restorations are suggested as an alternative method of treatment, and several advantages are described. Techniques to provide sufficient retention and resistance form include the use of threaded pins, amalgapins, slots and grooves, amalgam in the pulp chamber, or canals, or both, and posts cemented within the canals. The practicing clinician is advised to become familiar with these retention techniques so that difficult retention situations may be treated effectively.     

牙冠延长术用于前牙冠修复的牙周指标分析

目的：评价牙周基础治疗及牙冠延长术治疗前牙不良冠修复所致牙周病的临床疗效。方法：选取30例前牙冠修复所致牙周病患者共105颗患牙,均采用牙周基础治疗及牙冠延长术后再行冠修复,观察不同时段临床冠长度的变化,记录各相关牙周指数并进行分析,评估术后全冠修复的临床效果。结果：术后短期内临床冠长度增加效果确切,治疗组术后的各项牙周指数均优于术前（P＜0．05）,与对照组比较无明显差异（P＞0．05）,在1年的观察期内保持相对稳定（P＞0．05）;全冠修复体的固位良好,边缘密合,龈缘与冠缘的位置关系相对稳定。结论：牙周基础治疗及牙冠延长术有利于不良冠修复所致牙周病的治疗,且冠延长术解决了生物学宽度的问题,确保了牙周健康的长期稳定。     

磨牙残冠的核冠修复

用核全冠对２５个磨牙残冠进行了修复。冠核由螺纹冠钉，金属核套、银汞合金三部分构成。追踪观察修复后１年以后１６名患者的１７个患牙，未发现有修复体松动、脱落，患牙无继发龋发生，效果满意。该方法制作过程为分解进行，便于操作，宜于普及使用。     

老年人后牙残根残冠的铸造桩核冠修复

目的:本文旨在探寻和评价老年人后牙残根残冠的铸造桩核冠修复的临床效果.方法:对老年人可保留的后牙残根残冠,经过完善的根管治疗以后进行牙体预备,取印模、灌制模型,制作铸造桩核(多根牙时,加斜插式移动钉),临床粘结.在铸造桩核上进行全冠制备,取印模,完成全冠的制作,临床试戴、抛光、粘结,完成桩核冠修复.结果:1～3年随访观察,铸造桩核冠与牙体组织密合度良好,修复体无松动,冠周牙龈未见异常反应,X线片示无可见继发龋.结论:铸造桩核冠可以视为一种有效的方法,修复老年人残根残冠,以维持他们的正常咀嚼功能和口腔健康.     

The construction of a crown for clasp-bearing teeth

A method is described for the fabrication of clasp-bearing crowns. The technique involves the preparation of a thin gold transfer coping, on to which the bulk of the crown is cast in a later stage.     

Single appointment amalgam crown procedure for posterior teeth

When faced with the restoration of severely broken-down posterior teeth, many treatment options exist. Expense, time constraints, and periodontal health, as well as the needs and desires of the patient, all play a role in the selection of treatment modality. In many instances, a well-fabricated amalgam crown can provide a highly acceptable functional restoration in the posterior region. Here, the amalgam crown is discussed in relation to other options and several case reports are presented.