Ingle JI, Bakland LK, Baumgartner JC. Retreatment of non-healing endodontic therapy and management of mishaps, 6th edn. USA: People's Medical Publishing House; 2007
Smith BJ. The removal of fractured post fragments in general dental practice using ultrasonic vibration. Dent Update. 2002; 29:(10)488-491
Castrisos T, Abbott PV. A survey of methods used for post removal in specialist endodontic practice. Int Endod J. 2002; 35:(2)172-180
Abbott PV. Incidence of root fractures and methods used for post removal. Int Endod J. 2002; 35:(1)63-67
Carrotte P. Endodontic problems. Br Dent J. 2005; 198:127-133
Castrisos TV, Palamara JE, Abbott PV. Measurement of strain on tooth roots during post removal with the Eggler post remover. Int Endod J. 2002; 35:(4)337-344
Bando E, Kawashima T, Tiu IT, Kubo Y, Nakano M. Removing dowels in difficult teeth. J Prosthet Dent. 1985; 54:(1)34-36
Stamos DE, Gutmann JL. Revisiting the post puller. J Endod. 1991; 17:(9)466-468
Machtou P, Sarfati P, Cohen AG. Post removal prior to retreatment. J Endod. 1989; 15:(11)552-554
Altshul JH, Marshall G, Morgan LA, Baumgartner JC. Comparison of dentinal crack incidence and of post removal time resulting from post removal by ultrasonic or mechanical force. J Endod. 1997; 23:683-686
Sakkal S, Gauthier G, Milot P, Lemian L. A clinical appraisal of the Gonon Post-Pulling System. J Can Dent Assoc. 1994; 60:(6)537-542
Yoldas O, Oztunc H, Tinaz C, Alparslan N. Perforation risks associated with the use of Masserann endodontic kit drills in mandibular molars. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004; 97:513-517
Chandler NP, Qualtrough AJ, Purton DG. Comparison of two methods for the removal of root canal posts. Quintessence Int. 2003; 34:(7)534-536
Okiji T. Modified usage of the masserann kit for removing intracanal broken instruments. J Endod. 2003; 29:(7)466-467
Williams VD, Bjorndal AM. The Masserann technique for the removal of fractured posts in endodontically treated teeth. J Prosthet Dent. 1983; 49:46-48
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Anderson GC, Perdigao J, Hodges JS, Bowles WR. Efficiency and effectiveness of fiber post removal using 3 techniques. Quintessence Int. 2007; 38:(8)663-670
Gesi A, Magnolfi S, Goracci C, Ferrari M. Comparison of two techniques for removing fiber posts. J Endod. 2003; 29:(9)580-582
deRijk WG. Removal of fibre posts from endodontically treated teeth. Am J Dent. 2000; 13:19B-21B
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Failed root canal treatment is best addressed primarily with the provision of repeat endodontic treatment with thorough irrigation under isolation. If a post is present in the root of the tooth it needs to be removed first. This paper is the second in a series of two which provide an overview of techniques for post removal. Specifically designed post removal devices and the removal of fibre posts are described. Post removal device techniques are illustrated with a series of clinical case figures.
Clinical Relevance: Endodontic re-treatment has a more successful long-term outcome than surgical treatment for failed root canal treatment. This approach may involve the removal of existing post restorations.
Article
Jamie Dickie John McCrosson
This is the second paper in a series of two which aims to provide an overview of techniques used for the removal of posts from the root canal system. The first paper discusses the rationale for endodontic re-treatment, pre-operative assessment and factors affecting post removal techniques. This paper provides an overview of some devices specifically designed for post removal. Additionally, the removal of fibre posts is discussed.
Post removal systems
Most post removal systems work like corkscrews by creating opposing forces that can withdraw a post from the canal.1
Some of the systems described in this paper employ pulling forces in order to extract posts. Such forces should not be used for well-fitted threaded active (screw) posts as there is an unacceptably high risk of root fracture.1 Despite this, some of the following systems can still be used to remove such posts without use of their pulling component (see below).
Prior to their use, the coronal restoration should be removed1,2 and the underlying core should be reduced to expose the post head. Additionally, an ultrasonic scaler can be used to disrupt any accessible cement lute.2,3
Eggler
The Eggler post remover (Automaton-Vertriebs-Gesellschaft, Germany) (Figure 1) is usually used to remove posts in anterior teeth.4 It consists of a pair of gripping forceps and repeller arms, which are used to draw out a post using the residual root face for anchorage. In the authors' opinion, there is often insufficient space to utilize this device.
Figure 1. The Eggler post remover: a – gripping forceps; b – repeller arms; c – large inner wheel; d – thumbscrew.
Prior to use, the core should be reduced to a cube-shape of approximately 2 mm per side5 using a high-speed bur. Place the forceps over the core/post and turn the large inner wheel to grip. The smaller thumbscrew at the top of the Eggler is then tightened to lower the repeller arms. As the arms are lowered, they contact the residual root face, push against it in an apical direction and cause the forceps to move coronally away from the tooth, withdrawing the post.6
The arms must contact the root face surfaces uniformly and simultaneously. Incorrect positioning can result in point or shear stresses in the dentine, causing root fracture. If contact is uneven, probes and flat plastic instruments can be placed between the arms and the root face to facilitate the application of force along the long axis of the tooth. Care must also be taken when less than 1 mm of dentine surrounds the apical end of the post owing to the risk of root fracture.7
Figures 2 a–d show a case where a post and core were removed with the Eggler device. It should be noted that the UL2 has a poor long-term prognosis owing to previous horizontal bone loss (see Part 1 of this series), however, in this case the periodontal disease was stabilized and the patient wished to have the post removed along with endodontic re-treatment and a new post crown rather than extraction.
Figure 2.
(a) Radiograph of an intact post and core in UL2. (b) Clinical presentation after crown removal. (c) Eggler arms placed over the core to contact the root face and tightened by the large inner wheel before the small thumbscrew is turned to remove the post. Turning the thumbscrew: arms push against residual root face (blue arrows); forceps move coronally (yellow arrow). (d) The removed post and core.
Gonon (Thomas) Universal Post Remover
The Universal Post Remover (UPR) (Thomas, FFDM Pneumat, Bourges Cedex, France) (Figure 3) is a recent modification of the Gonon post remover which encompasses the removal of most posts available in the modern market, such as active (screw) and fibre posts. However, the technique for metal post removal remains largely unaltered. It conserves remaining tooth structure and reduces the risk of root fracture, perforation and application of torque forces on the root.8,9,10 A study by Altshul et al stated that it is a quicker removal method and resulted in fewer dentinal cracks when compared to the use of ultrasonic vibration alone.11
Figure 3. The Gonon (Thomas) Universal Post Remover: a – pliers; b – metallic and silicone washers of different diameters; c – FG diamond bur; d – pointeau drill; e – peeso reamer no 2; f – 2 sets of 4 taps; g – 2 sets of 4 trepans of different diameters.
After reducing the underlying core to expose the post head, use the kit's FG diamond bur to taper the post head. This will facilitate the centring of the trepan (a tool used to make a circular cut around the outside of the post either manually or with drilling). Select an appropriately sized trepan and bore/gauge the post head to the size of the corresponding tap. Position three washers onto the tap shank and turn the tap anticlockwise onto the post.1 Slide the washers down onto the tooth. These cushion the tap and equally distribute the forces applied to the root surface during the post extraction.12 Attach the kit pliers to the tap, with one jaw positioned against the washer covered root surface and fix the other jaw on the tap. Turn the knurled knob to move the plier jaws apart and extract the post.1
Since the UPR taps are screwed anticlockwise, they can also be used to unthread active posts (see Part 1). Refrain from using the plier in such cases. The kits pointeau and peeso reamer Nr 2 burs can be used to drill out fibre posts (see below).
Figures 4 a–g illustrate a case where the UPR was used to remove a post.
Figure 4.
(a) FG diamond bur tapering the post head. (b) No 4 trepan shaping the post head. (c) No 4 tap being placed over the prepared post. (d) Placement of the washers over the root face. (e) Application of the pliers. (f) The post hole after removal. (g) UPR pliers with the removed post.
The Ruddle Post Removal System
Designed by Dr Clifford Ruddle, the Post Removal System (PRS) (SybronEndo, CA, USA) (Figure 5) is designed to engage and remove passive posts (tapered and parallel), with a diameter of 0.6 mm or more,13 whilst preserving tooth structure. It is particularly useful for posterior teeth and is claimed to be an improved version of the Gonon system.1
Figure 5. The Ruddle Post Remover: a – trepans (0.6 to 1.6 mm in diameter); b – taps; c – transmetal bur; d –removal plier; e –rubber washers; f – torque bar.
If there is sufficient exposure of the post surface coronally, the PRS can be used to remove it. The system can still be used if the post head is below the level of the residual root face, however, if it becomes increasingly difficult to use, an alternative technique may need to be considered.2
There should be straight line access to the post, with the entire post circumference visible,13 as well as adequate interproximal space between the adjacent teeth for the extractor's jaws.2
Select the largest trepan bur that does not pass over the post head and attach it to a slowspeed, high torque handpiece. Round off 2–3 mm of the post head into a cylindrical shape with a ‘pecking’ motion. The resulting shape will correspond to one of the taps which should then be guided over the post with one of the rubber washers inserted over its shaft. This protects the remaining tooth structure from the force exerted by the plier. Turn the tap anticlockwise with firm apical pressure and small, quarter-turn motions. This results in the formation of threads and the post is actively engaged. The tap should not be advanced further than 4 mm.6
Slide the rubber washer down over the residual root surface and then mount the extraction plier onto the tubular tap with the jaws between the head of the tap and the rubber washer. Turn the screw knob clockwise to open the jaws and exert force along the post's long axis. Constantly check the tooth to ensure that it is adequately cushioned and protected. As the extractor is tightened the post should withdraw in a coronal direction.2,13,14
An ultrasonic scaler can be used in conjunction with the PRS by applying its tip to the engaging tap. This can disrupt the encompassing cement lute and allow further turns of the screw knob.11
Like the UPR, the PRS can also be used to ‘unscrew’ active posts13 due to the anticlockwise rotation of the taps (see Part 1).
A case where the PRS was used for post removal is shown in Figures 6 a–g.
Both the UPR and PRS exert extreme forces and therefore should be utilized with great care.
Figure 6.
(a) Ultrasonic removal of the encompassing composite core and cement. (b) The exposed post head. (c) Shaping of the post head with a trepan bur. (d) The post head after shaping. (e) Placement of the corresponding tap. (f) Application of the pliers with the lower jaw pushing apically on the washer covered root face (red arrow) and the upper jaw against the tap coronally (yellow arrow). (g) PRS pliers with mounted tap and removed post.
Masserann
The Masserann kit (Micro-Mega, Besancon, France) (Figure 7) was designed for the removal of metallic objects, such as posts, broken files and silver points, from the root canal. Some studies have described it as a technique that is sensitive, time consuming15 and difficult to use in posterior teeth.5 It does not work well for posts cemented with composite lutes.3,16
Figure 7. Masserann kit: a – gauges; b – spanners; c –long handle; d – trepans of varying sizes; e – flat gauge.
Nevertheless, if used in conjunction with an ultrasonic scaler and dental operating microscope, it can be an effective post removal method in selected cases.17 It is particularly useful for parallel-sided posts, and best avoided for oval and tapered custom posts.18 The technique is simple, generates no heat and there is no danger of pushing the post further into the root.19 Where possible, the kit's trepans should be used in the coronal third of the root canal where access is favourable and there is more remaining tooth tissue.20
After ensuring that there is adequate straight-line access, select a trepan which has an internal diameter that closely matches, or is slightly wider than, the diameter of the post. Check the trepan edges and sharpen, if necessary. These can be bent outwards during use and result in excessive removal of dentine, weakening the remaining tooth structure and increasing the risk of perforation or fracture.21
Slide the trepan over the post head and manually rotate it anticlockwise,6 advancing it along the post's outer surface. This cuts away the cement lute and loosens the post but, unfortunately, it can also cut away dentine. If the post is threaded, the trepan should cut along the threads, minimizing the amount of dentine removed.21 In addition to cutting, the trepans are designed to grip the post subsequently and remove it upon withdrawal. When extracting the post, it should be performed in rotation, ie not be pulled out in a vertical direction.
Alternating between an ultrasonic scaler and the Masserann is an effective removal method,1,20 which reduces the amount of dentine removal compared to use of the Masserann trepan alone.1 Ultrasonic tips can also be applied against the shank of a trepan placed over a post fragment to facilitate removal.
Figures 8 a–d illustrate a case where a fractured post was removed using a Masserann trepan.
Figure 8.
(a) Fractured post in UR2. Note the presence of a labio-palatal hairline fracture. Despite this, the tooth was clinically sound but of a poor prognosis. The patient wished to exhaust all restorative options instead of extraction. (b) A Masserann trepan advancing over the fragment, rotating anticlockwise. (c) The removed fragment in a Masserann trepan. (d) The removed post fragment.
Fibre posts
Fibre posts are composed of a composite matrix laced with carbon, glass or quartz fibres,22,23 and are bonded into the tooth using resin-based dentine-bonding agents. They can be drilled out using specific burs.23 Some fibre post systems come with their own corresponding removal kit (eg ParaPost XH, ParaPost Fibre White, Luscent Anchors and Aestheti-Plus).
Alternatively, long neck round ISO size 006 burs (D205 LN bur, Dentsply Maillefer, Ballaigues, Switzerland), Gates-Glidden burs (Dentsply Maillefer, Ballaigues, Switzerland) and peeso drills can be used to core out fibre posts.1,24 Lindeman et al suggested that the recommended removal kits were significantly more efficient, but the alternative use of diamonds burs and ultrasonics were more effective.25 They also suggested that the use of removal kits could be enhanced with subsequent ultrasonic instrumentation to eradicate any remaining fibres and cement.
The principle of each method is to create a pilot hole down the centre of the post before hollowing it out. Owing to their composition, fibre posts are unlikely to result in excessive heat generation as they are cut. However, it is still important to proceed slowly whilst cutting as their removal will result in a degree of canal widening,25 increasing the risk of perforation or root fracture.
Metal and ceramic posts can also be drilled out with diamond-coated burs, but they are difficult to remove successfully without causing significant damage. Cutting metal posts also leads to heat generation,21 which can cause damage to the periodontal ligament.26
Ceramic posts
At present, all available reports indicate that removal of these posts is either hazardous in the extreme or close to impossible.26 A Masserann trepan can be used to attempt removal20 but is unlikely to produce a successful outcome.
Flush
If a post fragment has been loosened but is proving difficult to grip and remove with either fine forceps or a Masserann trepan, it may be flushed out with saline or a suitable endodontic irrigant in a handheld syringe (Figure 9 a–c).
Figure 9.
(a) A loose fragment within the canal. (b) Irrigation of the canal with 0.9% sodium chloride (saline) solution. (c) The removed loose post fragment.
After removal
Once the post has been successfully removed the canal should be assessed for any fractures, perforations and/or other defects. If a perforation is detected, it must be determined as to whether it is reparable. Repeat root canal treatment and the provision of a new post crown can then be undertaken.
Conclusions
It should be remembered that, for all post removals, pre-operative assessment is vital in determining appropriate case selection, degree of difficulty of removal and appropriate choice of technique.
Prior to any removal attempt, patients should be warned about the risk of root fracture and, in most cases, it is advisable to construct an immediate partial denture in case this complication occurs.
The devices and techniques covered over these two papers are just some of the various post removal methods available. Their use has been described and the various advantages and disadvantages of each have been discussed. No single method always results in a successful outcome and, in many incidences, a combination of various techniques may be required. The authors would recommend sampling as many devices/techniques as possible, as there is a degree of personal preference and individual operator skill involved when it comes to performing a post removal procedure.
