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Azerbaycan Saytlari

 »  Home  »  Endodontic Articles 2  »  A survey of methods used for post removal in specialist endodontic practice
A survey of methods used for post removal in specialist endodontic practice
Discussion - References.

The data presented in this survey indicated that post removal is preferred to periapical surgery by the majority of endodontists in Australia and New Zealand. The most common reason for avoiding post removal was the presence of a wide post with thin root structure as it was felt that removal of these posts might cause the root to fracture. This view was given more often by those respondents who had experienced a root fracture during post removal. Nearly half of the respondents reported fracturing a root during post removal, although the number of fractured roots represented less than 0.002% of the estimated total number of posts removed. Those respondents who commonly used post removers were more likely to have experienced a root fracture when removing posts. However, this needs to be considered in relation to the number of posts removed during their careers and the extremely low overall incidence of root fractures. It was not possible to determine from this survey whether any of the roots that fractured already had incomplete fractures (or cracks) present prior to post removal. If an incomplete fracture or crack was present then it is very likely, if not a certainty, that it would propagate further during application of the post removal devices. Oblique fractures and fractures of small slivers of dentine were reported by some respondents. It is possible that these fractures, or their precursor cracks, may also have been already present in the tooth or, alternatively, they may have occurred due to the design and application of some of the post removal devices which place localized forces on the root face of the tooth.
Dentinal cracks were reported on the root face of some teeth in association with the use of ultrasonic vibration, although it is possible that these cracks were also present prior to post removal. During application of ultrasonic vibration to a post, the conductance of the vibratory forces along the post is proportional to the modulus of elasticity of the post, and materials with a higher modulus of elasticity will tend to conduct the ultrasonic vibration better. Altshul et al. (1997) compared the incidence of dentinal cracks in teeth after posts had been removed with either ultrasonic vibration or with the Gonon post remover and they reported a higher number of roots with intradentine cracks in the ultrasonic group even though vertical root fractures did not occur.
The use of the Auto Abdicator was associated with several root fractures in the current survey and this may be associated with the method of operation of this device, as well as application of the load at a different angle to the path of withdrawal of the post. The operation of this device is different to other post removal devices, because it provides a short and rapid load to the tooth. Clinically, it is not usually possible to control the direction of application of this load to the post which may lead to root fracture. It is also worth noting that this device is designed to be used for removing crowns rather than posts, although often the post will dislodge with the crown. This will occur if the post and crown have been cast as a single entity rather than as two separate castings, or if the adhesion of the luting agent between the post and dentine is not as strong as the adhesion of the luting agent between the post/core and the crown. When assessing teeth clinically prior to removal of crowns and posts, it is not often possible to determine whether these situations exist and the type of luting agent used is not generally known.
Ultrasonic vibration was the most frequently used technique for the removal of all examples of posts in this survey – that is, for cast posts and cores, fractured posts in anterior teeth, and parallel-sided preformed posts in both anterior and posterior teeth. It was used more often to remove posts from posterior teeth and this is probably due to the limited access available for the application of post removal devices in these teeth. It is also a relatively efficient technique as shown by Buoncristiani et al. (1994), who compared the efficiency of ultrasonic and sonic vibration when removing parallel-sided posts. They reported that both the Enac (Osada Electric Company, Tokyo, Japan) and Cavi-Endo (Dentsply, York, PA, USA) ultrasonic devices were able to remove posts in less than 10 min, although Altshul et al. (1997) reported that the time taken was significantly less with the Gonon device (2.3 0.9 min) than with ultrasonic vibration (7.7 4.9 min). The relative ease of use of ultrasonics with parallel, preformed posts is probably related to the design of these posts, as it is unlikely that they will fit well in the coronal third of most root canals. This allows for easy breakdown of the cement in the coronal third and subsequent ‘shifting’ of the fulcrum point toward the apical end of the post. As the fulcrum point shifts apically, the ultrasonic vibrations start to move the post about this point and within the space created in the coronal third. This movement helps to break down the cement toward the apical end of the post in conjunction with the breakdown caused by the ultrasonic vibration itself – hence there are direct and indirect effects of ultrasonic vibration. Ultrasonic devices are also used by some clinicians to remove cement from around the post with a fine ultrasonic tip.
In the survey by Stamos & Gutmann (1993), post removal devices such as the Eggler and Gonon (Thomas) post removers were the least commonly used devices because it was felt that they may cause root fracture, they could not be used universally, or they did not work. In contrast, in the current survey there was no correlation between the use of these devices and concerns that post removal may cause roots to fracture. However, there was an association between the use and the type of post removal devices and the university where postgraduate training had been completed. The overall use of post removal devices was much greater in this survey than in the Stamos & Gutmann (1993) study, with the Eggler being commonly used by 42% of the respondents. Although the Gonon (Thomas) and Ruddle post removers were available to over half of the respondents, only 9% actually used them. The greater popularity of the Eggler device may be a result of it being considerably easier to use than the Gonon or Ruddle post removers, which require the use of trephine burs to reduce the post or core to the appropriate size followed by a mandrel that is attached to the post/core during its removal.
Several respondents used more than one instrument to remove posts. The most frequent combinations were the initial use of ultrasonic vibration in association with subsequent use of a post removal device, forceps or haemostats. The initial use of ultrasonic vibration on a post for 2 min has been shown to reduce the amount of force required to remove the post by 30% (Berbert et al. 1995) and the results of this study may have influenced some respondents to use ultrasonics in this manner prior to using other devices to remove posts.


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