Removal Efficiency and Effectiveness of Four Different Fiber Posts Using Five Different Drill Systems in Multirooted Teeth

INTRODUCTION

Fiber posts (FPs) are commonly used in esthetic dentistry for restoring endo-treated teeth. These posts have several advantages in esthetic dentistry. Their esthetic integration, due to the tooth being colored and translucent, makes them an excellent choice for restoring anterior teeth. Being minimally invasive, attributed to their adhesive nature which allows for minimal removal of tooth structure during post placement. They reduce the risk of fracture due to their elastic modulus that is close to dentin, which reduces the risk of stress concentration and root fractures, a common concern with metal posts. Their excellent bonding capabilities can enhance the overall stability and longevity of the restoration. Added to their biocompatibility which reduces the risk of allergic reactions or adverse tissue responses.^1–3

On the other hand, FPs also have some potential disadvantages. It is important to consider both the advantages and disadvantages when choosing a post material for restorative dentistry.⁴ Their lower radiopacity compared to metal posts. This can make them less visible on X-rays, which might hinder the ability to detect any complications or recurrent caries around the post area. Added to their fracture risk in high-stress areas, influenced by factors such as post diameter and design. Their higher cost compared to metal posts, which can impact the overall cost of a dental restoration. Added to bonding challenges, the success of bonding depends on proper isolation and technique, and failure to achieve a reliable bond can compromise the longevity of the restoration. Their limited size and shape options, compared to metal posts, can make them less suitable for certain clinical situations.^5–8

The removal of an FP may become necessary in certain situations, such as post fracture, endodontic complications, recurrent caries, post dislodgment, or replacement of restoration.^8–11 Deciding to remove an FP should only be after careful assessment of the particular clinical situation, taking into consideration the patient’s needs, the condition of the tooth, and the overall treatment plan. The FP removal can be a delicate procedure that should be carried out with precision to avoid damaging the tooth structure. Several methods can be used for FP removal, and the selection of the method may depend on the specified clinical situation. Among these methods is manual extraction with pluggers or heated instruments to soften and remove the FP from the root canal. It is a controlled and minimally invasive technique. Ultrasonic removal to vibrate the post within the root canal, facilitating its loosening and removal. This method is minimally invasive and helps preserve tooth structure. Drilling and tapping FP to be loosened and tapped out of the canal. This method requires caution to avoid damage to the root.¹² Chemical softening may be used to weaken the bond between root dentine and the FP. After softening, the post can be gently removed. Laser removal of FPs also offers several advantages, including precise control, reduced damage to surrounding tissues, and minimized patient discomfort. In some cases, a combination of the previous methods may be necessary to safely and effectively remove an FP.^9,13–17

Fiber post removal in dentistry, while often necessary, can be a challenging procedure with potential drawbacks and complications. As the bonding agents used can be strong, removing the post without damaging the tooth can be a potentially difficult and time-consuming process. During the removal process, there is a risk of damaging the tooth’s structure, especially if the removal is not performed carefully or by an inexperienced practitioner. Tooth fractures or microfractures can occur. Patients may experience discomfort or pain during the removal process, which can be a drawback, especially if multiple attempts are needed. There is a risk of the FP fracturing during removal, which can complicate the procedure and potentially require more invasive techniques.¹⁸ And in cases where a crown covers the FP, its removal can damage the crown or necessitate a new one. In some cases, the removal process may lead to root perforations or fractures, which can be a serious complication. The success of FP removal can be unpredictable, depending on factors such as the type of post, the quality of the adhesive, and the technique used. If complications arise during the removal, additional dental procedures or restorations may be required, leading to extra costs and more time for the patient. The available clinical evidence and guidelines on FP removal are limited, making it important for dental professionals to have the necessary skills and experience.¹⁹

One common technique is the drilling and tapping method. This procedure involves carefully drilling a small access hole into the FP using a high-speed dental handpiece. Then after creating an access hole, a specialized instrument called a post remover or extractor is used. This instrument is inserted into the hole, and it grips the FP with small taps, allowing it to be unscrewed from the tooth. The FP is gradually unscrewed and removed from the tooth. The process is slow and controlled to minimize the risk of fracturing the post or damaging the tooth. While this method is commonly used, it is important to note that the specific instruments and techniques employed by dental professionals may vary. Additionally, the success of FP removal is dependent on numerous factors, such as the type of FP, the quality of the post cement, and the experience of the dentist.²⁰

It is somehow easy to locate the FP and its alignment in single-rooted teeth that are parallel to the tooth’s long axis. However, in premolars and molars, the state differs, where the used FPs are often narrower, although luted in the widest canals; lower distal and upper palatal canals that are never aligned with the long axis of these teeth. Because of this, it is challenging to guide the post removal drill within the vicinity of FP. Consequently, root perforations may be the result of off-axis drilling.^21,22 Only Lindemann et al. compared the time for FP removal with the time of titanium post removal.²³ This in vitro research compared the required time for metal and FP removal and examined the role of luting cements on the time needed to remove titanium posts.

In our work, the null hypothesis was that the difference between tested subgroups is non-significant.

MATERIALS AND METHODS

RESULTS

DISCUSSION

A similarity was observed among most of the previously done studies related to the selection of teeth that are used in the specimens. They were performed on single-rooted teeth, mainly maxillary central incisors which necessitate the placement of the widest diameter FPs that are easily directed along the long axis of the roots. A notable example of such research was conducted by De Rijk,²⁵ who illustrated the procedure of post removing as simple and quick. moreover, he posed that the structure of FPs is unique in its parallel fibers, stretched within a resinous matrix, which can supposedly guide the removal drill, keeping it within the post’s confines, and thus removing the risk of accidental perforations in the root. In his study, De Rijk²⁵ worked with carbon FPs, which give distinctive black shavings during drilling. This means that during post drilling, as long as the shavings are black the operator is still drilling within the post. On the contrary, tooth-colored shavings indicate off-axis drilling. However, tooth-colored FPs now dominate the market and thus shavings from both the tooth and the post are white. As a result, there is no longer a color difference between dentine and post shavings which had previously provided an easy indicator of off-axis drilling.

Another commonality among all previous studies done before was their in-vitro nature. Within these in vitro studies, it was reported that FPs can be removed relatively quickly and effectively.^23,26–28 In fact, being done in vitro and not intraorally reduces the challenge of post removal. It is one thing to negotiate and retrieve FP in a laboratory, handling a tooth that is easily accessible, and another thing to remove it under clinical conditions. Removing a post from a tooth in a patient’s mouth comes with obstacles of access, limitations of space, and hindered instrument maneuverability. Without a direct view of the tooth root, any dentist knows that during the clinical procedure of post removal, it is most difficult to align the drill along the axis of the unseen post. Under these circumstances, the operator can only verify the position of the drill by frequent radiographs, prolonging procedure time and exposing the patient to excessive radiation. In the event of the drill obliquely penetrating the post, it can cause serious damage to the radicular tooth structure.^29,30

This study includes a special category of FPs known as “Easy Removal FPs” (ERP). They were selected to be compared with the standard FP used as a control. Manufacturers of these ERP’s claim that they possess a unique feature that allows easy removal of the post whenever needed. The Hi-Rem post is an ERP with a soft and colored polymer core consisting of microfiber which supposedly guides the post removal drill along the center through a procedure of internal reaming. During removal, the colored microfiber can be clearly visualized at the post’s center.³¹ Accordingly, the drill can be inserted into the soft polymer microfiber at medium speed allowing the drill to penetrate the established full depth of the post. Then using Gates Glidden drills, the operator grinds the internal walls of the post until the cement and dentine are reached. Another unique post, the DT Light Post Illusion XRO exhibits an intrinsic color-coding of the post that can appear, disappear, and reappear on command. Upon applying a cold-water spray just for a few seconds, a color change occurs in the post, which assumedly can visually guide the operator in correctly directing the drill (Figs 3 and 4). Reforpost is composed of 85% glass fiber and 15% epoxy resin. It has been claimed that its composition and its longitudinal arrangement of fibers can guide the bur or drill along its length without deviation. In addition, it contains a 0.2 mm stainless steel wire down the middle. The control FP in this study was the Radix FP, a composite combination of a 60% epoxy resin matrix reinforced with 60% zircon-enriched silicon fibers arranged longitudinally and having shear strength and elastic modulus approximating that of dentine.

The post removing drills selected comprise four differently shaped drills and one post removal drill kit. The drill kit is composed of two successive drills, a pilot drill, and a carbide removal drill. The manufacturers of the drill kit claim that it is perfect for FP removal. The main issue of the Reaccess Carbide Double Taper Kit, however, is that the dentist must keep both drills as parallel as possible to the longitudinal axis of the post and sink it into the opening. The PD-25-1.1 Drill had never been used for post placement or removal. It was originally a pilot drill used in the placement of orthodontic microimplants. Based on the shape of its flutes, the authors hypothesized that it would make a good candidate for a successful post removal system, although its length may be an obstacle, rendering it less useful in the removal of longer posts. The other drills used all have different flute shapes and lengths.

As related to the post removal drills, the results showed that the Reaccess Carbide drill Kit displayed superior performance in effectiveness and efficiency compared to the other drills, followed directly by the PD-25-1.1 Drill. The worst performance belonged to the GC FP Drill. On the contrary, with regards to the type of post, the Hi-Rem post showed the best results upon removal. This may be attributed to its soft microfiber core. The Reforpost showed conflicting results across drill systems. This may be due to the stainless-steel wire in its core which could cause slippage with some drill designs. The D.T. Light-Post Illusion X-RO did not perform as expected by the author. Its color change feature was only helpful in the cervical 3 mm of the canal since it was no longer visible at a greater depth.

An interesting observation was made during the procedures. The GC FP Drill exhibited a sudden drop upon drilling to the middle third of the post. The reasons for the drop could be a difference in fiber count, direction, or tight pack between the cervical, middle, and apical thirds of the post. On the effectiveness scale, the GC FP Drill scored a 6, denoting off-axis drilling, twice, and the H-Endodontic Drill scored a 6 only once. All other drills did not deviate off-axis during drilling.

Unfortunately, there has only been one comparable research studying the removal of FPs in multirooted teeth, and it was conducted in 2014.³² The study resulted in no significant difference between the tested groups. The shortest mean post removal time was 9.5 minutes. It was concluded that the techniques that were used were not significantly effective or efficient in removing FP. This current study reached conflicting results to the aforementioned findings considering the reported shortest mean removal time was 1.4 minutes, and a strong significant difference (p = 0.00) was found regarding both types of posts and drill systems used. This demonstrates that FP removal depends on the FP type as well as the used drill system. However, it must be noted that a post that is easy to remove does not necessarily have the optimum mechanical properties, and that brings to light another important parameter in the selection of an ideal FP.

In addition to being conducted on multirooted teeth, the choice of drills used in this study is another strong point. This is especially true for the PD-25-1.1 orthodontic microimplant pilot drill, which was manufactured for a different purpose and was never intended for post removal. It was found, however, that its short shank may pose a problem when attempting to remove longer posts. A similar drill, the PD-31-101, has a longer handle, though its shank is the same length as that of the PD-25-1.1. The manufacturer of these drills may be advised to fabricate a drill more suitable for FP removal, by lengthening the drill shank.

However, in vivo studies on the removal of FPs are extremely difficult to implement and properly standardize. A significant sample size must be gathered of patients having the same type of post cemented in the same tooth number using the same resin cement, and all indicated for removal. It is difficult to successfully execute such a study without facing an ethical dilemma. A third and final drawback that must be mentioned is the lack of correlation between the post’s ease of removal and its mechanical properties. As previously mentioned, it would be undesirable to place an FP that is weak yet easy to remove. A fracture strength test could have been conducted alongside the study. This was not accomplished due to the large number of teeth (140) needed for this study. Future research of such scope is therefore justified.

CONCLUSION

Within the impediments of this work, the following can come to conclusion:

• Significant difference existed among all tested subgroups.

• Both tested FPs and drills had significant effect on post removal efficiency and effectiveness.

• The Reaccess Carbide Double Taper Kit performed superiorly with regards to both effectiveness and efficiency. PD-25-1.1 Drill followed.

• The Hi-Rem FP exhibited top outcome in removal as compared to the other posts.

REFERENCES

1. Ferrari M, Cagidiaco MC, Grandini S, et al. Post placement affects survival of endodontically treated premolars. J Dent Res 2007; 86(8):729–734. DOI: 10.1177/154405910708600808.

2. Mannocci F, Ferrari M, Watson TF . Intermittent loading of teeth restored using quartz fiber, carbon–quartz fiber, and zirconium dioxide ceramic root canal posts. J Adhes Dent 1999;1(2):153–158. PMID: 11725680.

3. Grandini S, Goracci C, Monticelli F, et al. SEM evaluation of the cement layer thickness after luting two different posts. J Adhes Dent 2005;7(3):235–240. PMID: 16240965.

4. Aydemir S, Arukaslan G, Sarıdağ S, et al. Comparing fracture resistance and the time required for two different fiber post removal systems. J Prosthodont 2018;27(8):771–774. DOI: 10.1111/jopr.12575.

5. Schwartz RS, Robbins JW . Post placement and restoration of endodontically treated teeth: A literature review. J Endod 2004;30(5):289–301. DOI: 10.1097/00004770-200405000-00001.

6. Lazari PC, Oliveira RC, Anchieta RB, et al. Stress distribution on dentin-cement-post interface varying root canal and glass fiber post diameters. A three-dimensional finite element analysis based on micro-CT data. J Appl Oral Sci 2013;21(6):511–517. DOI: 10.1590/1679-775720130203.

7. Ferrari M, Cagidiaco MC, Goracci C, et al. Long-term retrospective study of the clinical performance of fiber posts. Am J Dent 2007;20(5):287–291. PMID: 17993023.

8. Zicari F, Couthino E, De Munck J, et al. Bonding effectiveness and sealing ability of fiber-post bonding. Dent Mater 2008;24(7):967–977. DOI: 10.1016/j.dental.2007.11.011.

9. Franco EB, Lins do Valle A, Pompéia Fraga de Almeida AL, et al. Fracture resistance of endodontically treated teeth restored with glass fiber posts of different lengths. J Prosthet Dent 2014; 111(1):30–34. DOI: 10.1016/j.prosdent.2013.09.013.

10. Cheung W. A review of the management of endodontically treated teeth. Post, core and the final restoration. J Am Dent Assoc 2005;136(5):611–619. DOI: 10.14219/jada.archive.2005.0232.

11. Al-Omiri MK, Rayyan MR, Abu-Hammad O . Stress analysis of endodontically treated teeth restored with post-retained crowns: A finite element analysis study. J Am Dent Assoc 2011;142(3):289–300. DOI: 10.14219/jada.archive.2011.0168.

12. Purger LO, Tavares SJ, Martinez RL, et al. Comparing techniques for removing fiber endodontic posts: A systematic review. J Contemp Dent Pract 2021;22(5):587–595. PMID: 34318781.

13. Ferrari M, Vichi A, García–Godoy F . Clinical evaluation of fiber-reinforced epoxy resin posts and cast post and cores. Am J Dent 2000;13(Spec No):15B–18B. PMID: 11763866.

14. Giovani AR, Vansan LP, de Sousa Neto MD, et al. In vitro fracture resistance of glass–fiber and cast metal posts with different lengths. J Prosthet Dent 2009;101(3):183–188. DOI: 10.1016/S0022-3913(09)60025-1.

15. Cho J, Liu J, Bukhari EA, et al. Comparison of post space volume changes following fiber post removal using Er,Cr:YSGG laser versus ultrasonic instrument. J Prosthodont 2022;31(3):245–251. DOI: 10.1111/jopr.13391.

16. Papoulidou I, Dionysopoulos D, Mourouzis P, et al. Evaluation of Er,Cr:YSGG laser technique for fiber post removal of endodontically treated teeth using micro-computed tomography. Microsc Res Tech 2023;86(7):803–812. DOI: 10.1002/jemt.24340.

17. Dietschi D, Duc O, Krejci I, et al. Biomechanical considerations for the restoration of endodontically treated teeth: A systematic review of the literature, Part II (Evaluation of fatigue behavior, interfaces, and in vivo studies). Quintessence Int 2008;39(2):117–129. PMID: 18560650.

18. Sorrentino R, Di Mauro MI, Ferrari M, et al. Complications of endodontically treated teeth restored with fiber posts and single crowns or fixed dental prostheses: A systematic review. Clin Oral Investig 2016;20(7):1449–1457. DOI: 10.1007/s00784-016-1919-8.

19. Bitter K, Kielbassa AM . Post-endodontic restorations with adhesively luted fiber-reinforced composite post systems: A review. Am J Dent 2007;20(6):353–360. PMID: 18269124.

20. Haupt F, Riggers I, Konietschke F, et al. Effectiveness of different fiber post removal techniques and their influence on dentinal microcrack formation. Clin Oral Investig 2022;26(4):3679–3685. DOI: 10.1007/s00784-021-04338-0.

21. Rayyan MM, Hussien AN, Naguib H, et al. Fracture resistance of computer aided endo-crowns versus conventional core-supported computer aided full crowns. Int Arab J Dent 2019;10(2):54–59. DOI: 10.12816/0055609.

22. Dghaily D, Rayyan M, Ragab H, et al. Comparison of fracture resistance between different treatment modalities of mutilated endodontically treated teeth using polyether ether ketone. J Contemp Dent Pract 2023;24(9):668–673. DOI: 10.5005/jp-journals-10024-3558.

23. Lindemann M, Yaman P, Dennison JB, et al. Comparison of the efficiency and effectiveness of various techniques for removal of fiber posts. J Endod 2005;31(7):520–522. DOI: 10.1097/01.don.0000167397.60943.6e.

24. Lassila LV, Tanner J, Le Bell AM, et al. Flexural properties of fiber reinforced root canal posts. Dent Mater 2004;20(1):29–36. DOI: 10.1016/s0109-5641(03)00065-4.

25. De Rijk WG. Removal of fiber posts from endodontically treated teeth. Am J Dent 2000;13(Spec No):19B–21B. PMID: 11763867.

26. Gesi A, Magnolfi S, Goracci C, et al. Comparison of two techniques for removing fiber posts. J Endod 2003;29(9):580–582. DOI: 10.1097/00004770-200309000-00009.

27. Frazer RQ, Kovarik RE, Chance KB, et al. Removal time of fiber posts versus titanium posts. Am J Dent 2008;21(3):175–178. PMID: 18686770.

28. Anderson GC, Perdigão J, Hodges JS, et al. Efficiency and effectiveness of fiber post removal using 3 techniques. Quintessence Int 2007;38(8):663–670. PMID: 17823684.

29. Rayyan MM, Alwaely AM . Simplified technique for removal of prefabricated threaded posts. BAU Journal-Creative Sustainable Development. 2019;1(1):Article 6. DOI: 10.54729/2789-8334.1005.

30. Goracci C, Ferrari M . Current perspectives on post systems: A literature review. Aust Dent J 2011;56(Suppl. 1):77–83. DOI: 10.1111/j.1834-7819.2010.01298.x.

31. Alfadda A, Alfadley A, Jamleh A . Fiber post removal using a conservative fully guided approach: A dental technique. Case Rep Dent 2022;2022:3752466. DOI: 10.1155/2022/3752466.

32. Rayyan MM. Comparison of efficiency and effectiveness of fiber post removal in multi-rooted teeth using four different techniques. Egypt Dent J 2014; 60(2);2525–2553. DOI: 10.5281/zenodo.10523107.