A proposal for a new classification of lesions of exposed tooth surfaces

In the presence of improved methods of identification and treatment of lesions on the exposed surfaces of teeth, it should now be acknowledged that the GV Black "classification of carious cavities" is out of date. This paper describes a new system, proposed in 1997, discussed broadly throughout the profession, and eventually modified. The system has been adopted in several regions around the world as being a useful corollary to the current developing concept of minimal intervention dentistry. It is now desirable to adopt a new approach to the identification and recording of the lesions caused by both caries and non-carious tooth loss. A major advantage arising from its adoption would be that it would encourage the profession to minimise the amount of normal healthy tooth structure that is often sacrificed in pursuit of the cavity designs as suggested by Black. The authors are members of a Project Group of the FDI Science Committee, and this paper explains the concept and offers justification for the adoption of the system.     

ProTaper手动锉预备弯曲根管的临床评价

目的评价ProTaper手动锉预备弯曲根管的临床疗效。方法将40颗具弯曲根管需行根管治疗的患牙随机分为两组：试验组用ProTaper手动锉及冠根向技术预备根管，对照组用K锉及逐步后退技术预备根管。两组均采用侧向加压充填法充填根管，用X线片评价根管预备的效果。结果ProTaper手动锉组无根管偏移、根尖堵塞、台阶形成、器械折断等并发症发生，能维持根管的弯曲度和走向，根管锥度和流畅度佳；操作时间短，且术后疼痛发生率低。结论ProTaper手动锉预备弯曲根管快速、安全、有效，临床应用价值较高。     

试件形状和光滑度对纵折牙牙本质黏接微拉伸强度的影响

目的评价试件形状和牙本质黏接面磨光对纵折牙牙本质黏接微拉伸强度的影响。方法选择新鲜拔除的人完整磨牙及前磨牙15颗,用慢速切割机先去除牙齿咬合面的釉质,再沿牙齿近远中向或颊舌向纵切牙体至釉牙骨质界下,作为纵折裂缝,随机分为3组。A组折裂面用Super-Bond C&B树脂水门汀黏接后,制成哑铃形试件;B组黏接后,制成棒状试件;C组的折裂面用800目碳化硅耐水砂纸湿磨光1min后,再黏接,制成棒状试件。分别测试三组的微拉伸强度。结果A、B、C 3组的微拉伸强度分别为(7．75±2．67)MPa、(21．19±4．90)MPa、(27．56±7．60)MPa。棒状试件组(B组)的微拉伸强度高于哑铃形试件组(A组)(P=-0．0000);磨光组(C组)的微拉伸强度高于非磨光组(B组)(P=0．0088)。结论试件形状和对牙本质黏接面磨光与否对纵折牙的牙本质黏接微拉伸强度有影响。     

Er、Cr:YSGG激光根管内照射对根管封闭效果的影响

目的:探讨常规根管预备后使用不同能量的Er、Cr:YSGG激光进行根管内照射对根充后根管封闭效果的影响。方法:选择新拔除的单根管牙105颗,分成7组,每组15颗牙。切除牙冠后,常规进行根管预备。第1组不进行任何处理,作为阳性对照组;第2组为1W、有水激光照射;第3组为1W、无水激光照射;第4组为2W、有水激光照射;第5组为2W、无水激光照射;第6组为3W、有水激光照射;第7组为3W、无水激光照射。根充后进行根尖微渗漏检测,评估根管封闭效果。采用单因素方差分析(Anova)进行多组间总体均数比较,q检验进行组间比较。结果:除3W无水组外,其他各激光组与对照组相比,根尖微渗漏深度均有显著性差异(P<0.05);其中1W无水组与对照组相比具有高度显著性差异(P<0.01)。结论:较低能量(除外3W、无水)Er、Cr:YSGG激光进行根管内照射,能够有效提高根管充填后的封闭效果,其中1W、无水激光照射时根管封闭效果最好。     

Atomic analysis and knoop hardness measurement of the cavity floor prepared by Er,Cr:YSGG laser irradiation in vitro

In the present study, the compositional changes and knoop hardness of the cavity floor prepared by Er,Cr:YSGG laser irradiation was compared with that of the conventional bur cavity. Fifteen laser and 15 bur cavities were cross-sectioned, and subjected to atomic analysis by SEM-EDX and knoop hardness test. Statistical analyses were performed using the Mann-Whitney U-test; a value of P < 0.01 was considered significant. Surface characteristics of the prepared cavities were also investigated by light microscopy and scanning electron microscopy (SEM). The results showed that the quantities of Ca (Ca weight %) and P (P weight %) were increased significantly in the laser cavity floor but no significant differences were found between the Ca/P ratio and knoop hardness number of laser and bur cavities. The SEM observation revealed that the lased cavity surface was irregular and there was also the absence of a smear layer; the orifice of dentinal tubules was exposed. Er,Cr:YSGG laser device is considered as one of the most effective and safe devices for cavity preparation because of its many advantages. This includes easy delivery system, minimal thermal damage to the surrounding tissues, minimal thermal-induced changes of dental hard tissue compositions, and favourable surface characteristic.     

EFFECT OF IMMEDIATE AND DELAYED POST SPACE PREPARATION ON THE APICAL SEAL OF ROOT CANALS OBTURATED WITH DIFFERENT SEALERS AND TECHNIQUES

During mechanical preparation of the post space, the root canal filling may be twisted or vibrated, depending on several factors associated with the preparation technique and quality of filling.

Objective:

The purpose of this study was to investigate the effect of immediate and delayed post space preparation on the integrity of the apical seal.

Material and Methods:

Sixty-four extracted human incisors were biomechanically prepared using the step-back technique. Sixty roots were randomly assigned to 6 experimental groups of 10 teeth each and the remaining 4 roots served as positive and negative controls (n=2). The root canals in the different groups were obturated with cold lateral and warm vertical condensation of gutta-percha and one of two sealers (Sealapex and Diaket). Post space was prepared either individually or simultaneously. An insulated copper wire was cut into 10-cm-long pieces. In each canal, one piece was inserted to maintain contact with gutta-percha and extended to the outside as one of two working electrodes. A stainless steel wire with the same dimensions of those of the copper wire, used as the other working electrode, was immersed into the background electrolyte from the center of the bottle. The electrical current between standard and experimental electrodes in canals was measured over a period of 10 days applying a conductivity meter. The Kruskal-Wallis test (p=0.05) determined whether there was a significant difference in microleakage among the groups and the Mann-Whitney U test (p=0.01) was used for multiple comparison grouping variables.

Results:

The results suggest that only the differences between the root canal filling techniques were statistically significant (p<0.01). There were no statistically significant difference in the sealers and the times of filling removal for post space preparation (p>0.01).

Conclusion:

The quality of the root canal filling is important for the integrity of the apical seal.     

手用ProTaper镍钛锉与不锈钢H锉根管预备的临床疗效

目的比较手用ProTaper镍钛锉与标准手用不锈钢H锉根管预备的临床疗效。方法选择100例患者需作根管治疗的120颗患牙随机分为实验1组和实验2组,每组60颗患牙。实验1组使用标准手用不锈钢H锉和逐步后退法预备根管;实验2组使用手用ProTaper镍钛锉和冠向下预备技术预备根管。根管治疗完成后,随访3个月,观察临床疗效。结果实验2组根管治疗后疗效明显优于实验1组,其差异有统计学意义(P<0.05)。结论手用ProTaper锉系统柔韧性好,治疗成功率高,值得临床推广应用。     

IN VITRO EVALUATION OF ROOT CANAL PREPARATION USING OSCILLATORY AND ROTARY SYSTEMS IN FLATTENED ROOT CANALS

Objective:

The aim of this study was to evaluate the biomechanical preparation of flattened root canals using the following systems: Endo-Eze AET stainless steel oscillatory instruments (Ultradent) and RaCe rotary NiTi instruments (FKG Dentaire).

Materials and Methods:

Twenty extracted human mandibular incisors were randomly assigned to two groups: Group 1 - Instrumentation with oscillatory Endo-Eze AET files (oscillatory technique); Group 2 - Instrumentation with rotary NiTi RaCe files (rotary technique). The teeth were decoronated, had their apices and coronal openingssealed with sticky wax and were embedded in crystal-clear orthophtalic polyester resin. The roots were sectioned transversally with diamond discs at 10 mm (middle third) and 5 mm (apical third) from the apex and the segments were reassembled for instrumentation. The sections were photographed before and after root canal instrumentation and evaluated with respect to whether the original root canal shape was modified by instrumentation. To evaluate the differences in the root canal shape before and after biomechanical preparation, scores were given regarding the instruments touch on the intracanal walls.

Results:

In middle third of the root canals instrumented with the rotary system, there was a change in the original canal anatomy (p<0.05), with formation of a protuberance in the mesiodistal direction. This protuberance did not occur when the oscillatory instrumentation was used. The oscillatory system had better results in the middle and apical thirds as evaluated by Dunn’s multiple-comparison test (p>0.05).

Conclusion:

Under the tested conditions, Endo-Eze oscillatory system yielded the instrumentation of all flattened root canal walls, maintaining the canal original shape throughout the biomechanical preparation, and was more effective than RaCe rotary system.     

根管预备并发症及充填质量的临床评价

目的：对根管预备并发症及充填质量进行临床评价。方法：从Digora图像系统中抽取我科2002—04—05所完成的根管治疗病例805例，分别对前牙、前磨牙和磨牙根管预备并发症的发生和充填质量进行分析。结果：形成台阶和侧穿的比例在前磨牙分别为4％，而在磨牙中则分别为33％和5％。前牙、前磨牙和磨牙适充的比例分别为74％、69％和50％。结论：磨牙根管预备和充填的质量仍有待进一步提高。     

硼酸铝（9Al2O3.2B2O3）晶须的制备和性质

目的：制备硼酸铝晶须及测其物理化学特征。方法：原料在电炉中加热至１１５０℃，４ｈ，获得的晶须采用化学方法确定其组成，物理化学方法检测其表征。结果：获得了晶须的化学组成、Ｘ射线粉末衍射图、ＦＴ－ＩＲ光谱和Ｒａｍａｎ光谱图。结论：制备的晶须为四硼酸十八铝。