Orange oil technique for gutta percha removal near open apices in root canal re-treatment

Apical lesions in root canal-treated mature teeth, especially in cases with suboptimal root canal treatment,¹ are of concern as these lesions can progress into apical inflammatory root resorption, which in turn can lead to the formation of an open apex.² When faced with such clinical scenarios, the choice of retreatment becomes crucial.³ This decision is driven by the need to prevent an unfavourable crown–root ratio and promote the healing process to preserve the integrity of the natural tooth and avoid an extraction.

Removing gutta percha from irregular root canals of root canal-treated teeth (RCTT) can be challenging, particularly when conventional methods using retreatment files may prove to be less effective. The inefficiency of these methods can potentially lead to excessive dentine removal, resulting in root weakening, canal transportation, or strip perforation. Moreover, there is a risk of extruding gutta percha beyond the open apex, which can trigger a foreign body reaction, potentially delaying or impeding the healing process or causing a flare-up that may necessitate apical surgery or lead to post-operative discomfort.⁴

When these gutta percha remnants remain at the apex of the RCTT, they may risk compromising the apical seal, regardless of whether gutta percha or a hydraulic cement is chosen to fill the root canals. This can reduce the success rate and, in some cases, conceal underlying necrotic tissue or bacteria. As such, addressing the challenge of gutta percha removal in irregular canals with open apices is of particular importance in maintaining effective root canal treatment outcomes.⁵

The objective of this clinical advice is to provide a practical approach for the thorough removal of gutta percha remnants near open apices in re-treatment procedures, specifically after initial bulk removal.

Clinical technique rationale

To address this challenge, the proposed technique uses orange oil to dissolve these remnants effectively without causing harm to the peri-apical tissues.

Initial scenario

The pre-operative peri-apical radiograph reveals apical inflammatory root resorption, leading to an open apex with gutta percha extrusion (Figure 1). A residue of gutta percha remains in the apical region of the distal root, adjacent to the open apex, following the removal of the bulk of gutta percha material (Figure 2). This clinical scenario serves to describe the technique tip that can be adopted by general dental practitioners and specialists.

Technique description

Start by estimating the distance on the radiograph from a reference point to the area where the gutta percha remnants are located (Figure 3).

• Apply orange oil (orange guttane, 100% orange oil; Cerkamed, Poland) using a side-vented irrigation tip, positioning it approximately 2–3 mm from the open apex. Deliver approximately 1 ml, focusing on adequately filling the canal up to the orifice.
• Improve the dissolution by using manual agitation or applying sonic activation. This procedure can be repeated as necessary, although typically once or twice is sufficient to clear the remnants.
• Attach a flat-ended irrigation tip (EndoTech, Halifax, Canada) to a new 5-ml syringe. The use of a new syringe gives better visibility of the dissolved gutta percha within the orange oil.
• Insert the tip of this needle to the same depth as the orange oil was delivered.
• Apply negative pressure to withdraw the solution containing orange oil and dissolved gutta percha (Figure 4).
• Take a radiograph to confirm the successful removal of these remnants. Following this confirmation, the re-treatment protocol can proceed in the usual manner (Figure 5).

Discussion

A recent scoping review highlighted a consistent presence of intracanal gutta percha remnants, with a higher frequency and increased abundance in the apical third of the root.⁶ To date, no technique has definitively outperformed conventional methods for the removal of gutta percha remnants in the apical third of the RCT roots.^7,8,9 The proposed technique offers distinct advantages, ensuring a less invasive, more predictable, and cost-effective removal of these remnants. It requires only syringes, irrigation tips and a bottle of orange oil, along with the option for manual agitation or sonic activation.

Conversely, traditional solvents like chloroform, xylene, and halothane, while effective in dissolving gutta percha, can carry a risk to the peri-apical tissues, particularly in cases with an open apex.⁷ The proposed technique mitigates such risks, leading to more predictable outcomes with fewer complications or catastrophic events such as tooth loss.

The cytotoxicity of chemical solvents, such as chloroform, has been extensively established through various in vitro and in vivo studies, while organic solvents, such as orange oil are recognized for their lower cytotoxicity and reduced potential harm to peri-apical tissues.^{8,9,10,11,12,13,14,15} Overall, this approach provides a valuable alternative for dental practitioners performing root canal re-treatment procedures, combining efficacy with safety, making it a compelling option in addressing the challenge of gutta percha removal near open apices (Figures 6 and 7).

The practical limitations of the proposed technique should be acknowledged, however. First, achieving complete clearance of gutta percha remnants may sometimes necessitate multiple attempts. While the technique offers minimally invasive removal and predictability advantages, dental practitioners should be mindful that certain remnants may prove more resilient and require additional applications. Also, while an effective solvent for gutta percha, orange oil requires careful application because it can potentially damage or dissolve rubber dam used for tooth isolation.

Despite these limitations, the proposed approach presents a promising alternative for addressing the challenge of gutta percha removal near open apices. It balances efficacy and safety, making it a valuable option for general dental practitioners to address root canal re-treatment cases.

Conclusion

To sum up, the use of orange oil for gutta percha removal near open apices in root canal re-treatment is a cost-effective and practical technique. However, multiple attempts may be needed, and caution is advised to protect the rubber dam during application. This technique offers a promising balance between effectiveness and safety, improving predictability in complex endodontic cases.