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牙髓根尖周病是一类主要因细菌感染引起的、发生于牙髓及根尖周围组织的炎症性疾病,发病率高,是口腔常见病、多发病,占口腔内科门诊的60%,也是导致牙痛、失牙的主要原因.     

根管治疗与根折的关系

根折是根管治疗后常见并发症。很多研究已经显示过度的根管预备,充填时对根管壁产生的应力以及治疗过程中用到的药物、试剂都会直接或间接引起牙根纵折。为了更合理地选择治疗方案,减少医源性的因素导致的根折,本文就根管治疗过程中可能增加根折易感性的因素作一综述。     

Rapid orthodontic extrusion of crown root and cervical root fractured teeth

Abstract This study concerns the relapse tendency and extent of root resorption in 33 extruded non-vital crown root fractured or cervical root fractured teeth in 32 patients 10–20 years old. They constitute all orthodontically extruded teeth at the Orthodontic or Pedodontic Departments, Eastman Institutet, Stockholm (1982–1987). A simple extrusion mechanism exerted a force of 60–70 p along the root axis of the tooth. An extrusion of 2–3 mm was obtained in most patients; the most extreme effect was 6 mm. In 16 patients the extrusion was achieved within 3 weeks, in 12 it lasted for 4–6 weeks and in 5, 7–9 weeks. The treatment was more complicated in the lower jaw. After the extrusion, a fibrotomy was done and in most patients also a gingival recon–touring to create an optimal relation between the gingiva and the margin of the restoration. Periodically identical radiographs were taken immediately before and after the extrusion, after 3 months and after 1 year. A minor relapse, about 0.5 mm, was observed in 3 patients. Limited root resorption was found in 6 teeth and severe in only 1. The resorptions did not progress in the following 2 years of observation.     

The removal of gutta-percha and root canal sealers from root canals

The removal of gutta-percha from root-filled teeth is required for re-treatment of failed endodontic treatment and to prepare a space for placement of a post. Complete removal of filling material and sealer is a requirement for success. A review was undertaken of the current literature on methods of gutta-percha and sealer removal. Clinical recommendations based on current evidence are included. A combination of methods may be required to remove filling materials effectively.     

Vertical root fracture and root distortion: effect of spreader design

The incidence of vertical root fractures and the amount of root distortion created during lateral condensation of gutta-percha with either D11 spreaders or B-finger pluggers were evaluated in vitro. Fifty-five extracted human, single-rooted teeth were instrumented using the step-back flare technique. Ten teeth served as positive controls (obturation to the point of fracture) and five teeth as negative controls (prepared but not obturated). Strain gauges were attached to the root surfaces. In the experimental group, 20 teeth were obturated using a D11 spreader and 20 with a B-finger plugger. Recordings were made of root distortion (expansion) created during obturation. Then, after sectioning the teeth, root surfaces of obturated samples were examined for fractures under the scanning electron microscope. Only the more tapered spreader, the D11, produced vertical root fractures, although very few in number. Also, the D11 spreader caused greater root distortion than did the B-finger plugger.     

A new system for classifying root and root canal morphology

Knowledge of root and root canal morphology is a prerequisite for effective nonsurgical and surgical endodontic treatments. The external and internal morphological features of roots are variable and complex, and several classifications have been proposed to define the various types of canal configurations that occur commonly. More recently, improvements in nondestructive digital image systems, such as cone‐beam and micro‐computed tomography, as well as the use of magnification in clinical practice, have increased the number of reports on complex root canal anatomy. Importantly, using these newer techniques, it has become apparent that it is not possible to classify many root canal configurations using the existing systems. The purpose of this article is to introduce a new classification system that can be adapted to categorize root and root canal configurations in an accurate, simple and reliable manner that can be used in research, clinical practice and training.     

Effect of canal preparation and residual root filling material on root impedance

Aim To investigate the effect of root canal preparation and residual root filling material on the impedance characteristics of extracted human roots. Methodology Thirty extracted, human single‐rooted teeth were mounted in a custom‐made apparatus that allowed strict temperature control. Impedance measurements of the roots were made with a file acting as the internal electrode, using a frequency response analyser. The measurements were made under three canal conditions: (i) before chemo‐mechanical preparation; (ii) after chemo‐mechanical preparation; (iii) after root filling removal to re‐establish patency (following placement of root filling). The measurements were taken at 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm coronal to the apical terminus and also at 0.5 and 1 mm past the apical terminus. Impedance values were viewed using Nyquist plots and comparisons made within each tooth, between measurement points along the length of the canal, as well as under the different canal conditions. Equivalent circuits were modelled for different test conditions. Results The impedance decreased from the coronal to the apical levels in all canal conditions in a characteristic way, with an exaggerated drop at the apical terminus. Impedance decreased after chemo‐mechanical preparation, but gave higher values compared with before or after instrumentation, once canal filling had been removed. Equivalent circuits remained consistent at the tested positions within the canal, regardless of canal condition, but the circuit component values changed with the impedance. Conclusions Impedance was influenced by corono‐apical position, chemo‐mechanical preparation and residual root canal filling material.     

Influence of tooth age and root section on root dentine dye penetration

Aim To investigate dye permeability of root dentine according to patients’ age, root section and dye penetration time. Methodology A total of 96 extracted human single‐rooted teeth, assigned to four age groups (<30, 30–45, 45–60 and >60 years) were separated at the cemento–enamel junction and root canals were enlarged. The root surfaces were coated with cyanocrylate to prevent external dye penetration and centrifuged in distilled water to eliminate air. For dye penetration the root canals were filled with methylene blue 5%. After 1, 30 and 60 days eight roots per age group were cross‐sectioned in 1 mm slices. Dye penetrated areas and the complete dentine areas were digitized and measured. Differences between groups were judged with anova and LSD, P < 0.05 or P < 0.01. Results The root section, the patients’ age and the penetration time influenced significantly the penetrated areas (P < 0.05). After 1 and 30 days significant differences could be found only in the apical root sections between all age groups (P < 0.05). Dye penetration areas systematically decreased with increasing age and also from coronal to apical (P < 0.01). Conclusions Age influenced dye penetration significantly. Dye penetration also depended on the location (coronal, middle and apical) within the root canal. These findings indicate that there may be a correlation between the tooth age and permeability of root dentine, which may influence the distribution and effectiveness of drugs used for root canal disinfection.     

Spreading of root canal irrigants on root dentine

The purpose of this study was to evaluate the spreading of root canal irrigants on human root dentine. The spreading of various solutions on dentine surfaces was measured after pre-treatment with various conditional solutions. Seven experimental groups were set based on the combination of conditioning solution-test solution: none-distilled water; none-6% sodium hypochlorite (NaOCl); none-14.3% ethylenediaminetetraacetic acid containing surfactant 0.084% cetrimide (Morhonine); NaOCl-NaOCl; NaOCl-Morhonine; Morhonine-Morhonine and Morhonine-NaOCl. After application of 0.1 mL of conditioning solution for 60 s, 0.5 microL of test solution was placed on dentine surfaces. Spreading of test solution was measured for 480 s to examine the size of the contact area ratio. Those at 300 s were compared among groups using Fisher's Protected Least Significant Difference (P < 0.05). It was concluded that the contact area ratio of Morhonine-NaOCl increased the most significantly among all the experimental groups.     

双根双根管上颌侧切牙根管治疗1例

根管治疗成功的关键在于根管系统的彻底清创消毒和严密三维充填[1]。对于多根牙,为保证根管治疗成功,要求彻底清创消毒和严密充填每个根管。遗漏根管意味着该根管里残留大量感染物质,可能导致该患牙根管治疗的失败。一般来说,主根管通常比较容易找到,寻找额外根管相对较为困难,对于临床医师技能要求较高。     

Aberrant root formation: review of root genesis and three case reports

The mechanism of root formation and tooth eruption is a complex process which is not fully understood. Prior to a tooth emerging into the oral cavity, root genesis is initiated by derivatives of the enamel organ. The dental follicle mediates an eruption pathway allowing for movement of the developing tooth in a coronal direction. As the tooth moves towards the oral cavity, root formation occurs passively in the resulting space. Failure of the enamel organ and dental follicle to properly coordinate may result in complications in the eruption process. This clinical report presents 3 cases of isolated, unerupted teeth with dysmorphology of the roots. The process of root development and tooth eruption is also briefly reviewed.     

Rapid orthodontic extrusion of crown root and cervical root fractured teeth.

This study concerns the relapse tendency and extent of root resorption in 33 extruded non-vital crown root fractured or cervical root fractured teeth in 32 patients 10-20 years old. They constitute all orthodontically extruded teeth at the Orthodontic or Pedodontic Departments, Eastman Institutet, Stockholm (1982-1987). A simple extrusion mechanism exerted a force of 60-70 p along the root axis of the tooth. An extrusion of 2-3 mm was obtained in most patients; the most extreme effect was 6 mm. In 16 patients the extrusion was achieved within 3 weeks, in 12 it lasted for 4-6 weeks and in 5, 7-9 weeks. The treatment was more complicated in the lower jaw. After the extrusion, a fibrotomy was done and in most patients also a gingival recontouring to create an optimal relation between the gingiva and the margin of the restoration. Periodically identical radiographs were taken immediately before and after the extrusion, after 3 months and after 1 year. A minor relapse, about 0.5 mm, was observed in 3 patients. Limited root resorption was found in 6 teeth and severe in only 1. The resorptions did not progress in the following 2 years of observation.     

Periodontal esthetics and soft-tissue root coverage for treatment of cervical root caries

As the pace of change accelerates in periodontics and esthetic dentistry, an increasing number of procedures are being developed that require knowledge and treatment from both fields. The synergy developed by combining these two fields of dentistry allows for better esthetic outcomes for our patients. Two of these procedures include esthetic crown lengthening and soft-tissue root coverage. As demonstrated in this article, soft-tissue root coverage can be performed on previously restored roots and as an option for treating root caries.     

677个下颌第一磨牙牙根和根管数目分析

目的：调查下颌第一磨牙的牙根和根管数目，以期为临床治疗提供指导。方法：选取需治疗的下颌第一磨牙，采用X线片观察牙根数目和扩大针探查根管数目。结果：在677个下颌第一磨牙中，2个牙根的发生率为84．9％（575／677），为近中根和远中根，3个牙根的发生率为15．1％（102／677），为近中根、远中根、远中舌根；2个根管的发生率为0．1％（1／677），为近中远中各1个根管，3个根管的发生率为74．7％（506／677），为近中2根管，远中1根管，4个根管的发生率为25．1％（170／677），为近中2根管，远中2根管。2个牙根4根管的发生率是11．8％，3个牙根4根管的发生率是100％。结论：远中舌侧牙根（RE）的出现增加了4个根管的发生率；在根管治疗术时对牙根和根管数目的仔细检查非常重要。     

Hemisection and root amputation

The disciplines of endodontics and periodontics fuse when molars that have bifurcation or trifurcation involvements are treated with hemisection and root amputation. Attempts to save parts of teeth go back 100 years or more, but it is the increased predictability of success of endodontic therapy and the increased sophistication of periodontal treatment that have given us the means to save molars with furcation problems that, otherwise, would be lost. Even when less invasive modes of therapy have failed (scaling, root planing, occlusal adjustment, and flap surgery perhaps with osseous recontouring and synthetic or natural bone grafting material where indicated), it is no longer necessary to lose a molar with complete furcation problems. When restorative dentistry has already been finished, and the retention of part of the tooth will extend the life of a crown or fixed partial denture, the patient certainly deserves the option of hemisection or root amputation rather than extraction.