A Consensus‐Based Glossary for Controversial Terminology in Root and Canal Anatomy

ABSTRACT

Aim

To produce a glossary of controversial terminology relating to a variety of anatomical features of root canals.

Materials and Methods

A multi‐stage consensus process was designed and applied to generate definitions for controversial terms describing root and canal anatomy. The overall direction of the project was provided by an Executive Group, whereas a separate Task & Finish Group was convened to compile a preliminary list of controversial terms together with proposed definitions. This draft was then circulated to an international panel of 32 experts, who took part in an anonymous, web‐based Delphi exercise to give independent feedback. Findings from this Delphi round were subsequently examined and debated during a virtual meeting.

Results

Following the Delphi exercise, 14 of the 15 proposed terms achieved the pre‐specified consensus threshold, with more than 70% of respondents rating them above 7. Consensus was not initially reached for the remaining term (‘furcation accessory canal’); its definition was subsequently amended and put through a further Delphi round, after which agreement was achieved. A follow‐up virtual meeting involving 19 experts reviewed the Delphi outcomes and proposed further refinements. In response, the Executive Group and Task & Finish Group prepared the final version of the glossary.

Conclusion

Through a rigorous, structured process of international expert consensus, a glossary addressing controversial terminology in root and canal anatomy has been established. This resource offers a dependable basis for consistent, standardised terminology going forward, with relevance across clinical practice, teaching and research.

1. Introduction

A comprehensive understanding of root and canal anatomy is fundamental when undertaking endodontic procedures as inadequate anatomical knowledge may compromise treatment outcomes (Cantatore et al. 2006; Vertucci 2005). Over the years, laboratory‐based and clinical studies enhanced understanding of root and canal morphology; however, confusion has arisen over the use of several anatomical terms and their definitions. With the growing body of evidence and the increasing number of publications on the subject (Ahmed 2022; Versiani et al. 2023), the need for standardised and consistent terminology to describe the anatomical features of root and canal systems has become ever more critical (Ahmed et al. 2023, 2024).

The standardisation and consistent use of terminology not only enhance accuracy and understanding but also play a crucial role in improving dental education, comparisons between research findings and enabling more precise descriptions of the wide range of anatomical variations encountered in dentistry. However, a universal consensus on many of the terms used to describe and define root and canal anatomy is lacking (Ahmed et al. 2024). For students, researchers, clinicians and scientists to understand and interpret root canal configurations accurately and consistently, the anatomical features of roots and root canal systems must be clearly defined using terminology that is both universally applicable and accepted.

Recently, a project was initiated to identify a range of controversial and inconsistently used terminology in endodontology, with the aim of developing a universally accepted standard glossary (Ahmed et al. 2023). This initiative seeks to enhance clarity in education, research and clinical practice, and to promote more effective communication among key stakeholders, including patients, students, clinicians, researchers and regulatory authorities (Ahmed et al. 2023). The present paper reports the outcome of this project and introduces a consensus‐based glossary of controversial terms and definitions related to root and canal anatomy for universal adoption.

2. Methodology

2.1. Study Preparation

The institutional ethics committee, Faculty of Dentistry, Universiti Malaya [Ethics approval number DF RD2524/00104 (L)] approved the project.

The importance of developing a series of consensus‐based glossaries for controversial terms in a range of fields within endodontology was agreed by the project leaders who comprised the Executive Group (HA, VN, HD, OP, PD) (Ahmed et al. 2023). To create a glossary of controversial terms that were specifically relevant to root and canal anatomy, the Executive Group established a Task & Finish Group of seven members (HA, VN, HD, OP, PD, TW, AK). An initial draft list of controversial terms and definitions was established and then presented to a wider group of experts to obtain feedback and ultimately arrive at a consensus.

2.2. Online Delphi Survey

The Executive Group established a panel of experts from around the world to participate in the online Delphi survey. The academics and clinicians included had to satisfy at least one of the prerequisites in order to participate, that is: (1) published at least two studies on root and canal anatomy; (2) published reporting guidelines for manuscripts; (3) a minimum of ten years of academic, research or clinical experience in dentistry.

Members of the Executive Group (HA and VN) sent an invitation letter via email to a variety of experts (n = 55) from around the globe, outlining the aims and objectives of the project and asking whether they would take part in a Delphi survey. Individuals who consented to participate were provided with further details about the online Delphi approach and the list of draft controversial terms and definitions. The accuracy and suitability of the terms and definitions were then assessed independently and anonymously by each member using a Google Form. The clarity of each item was assessed using a dichotomy scale of ‘yes’ or ‘no,’ while the applicability of each item was assessed using a 9‐point Likert scale (1 indicating ‘definitely not include’ and 9 indicating ‘definitely include’). Members also gave feedback on each term and its definition, and were also able to suggest new terms for inclusion.

The Executive Group assessed the scores allotted to each term and definition. All terms/definitions that received a score between 7 and 9 from ≥ 70% of members and between 1 and 3 from ≤ 30% of members were included. Similarly, terms/definitions were excluded if ≥ 70% of members rated them between 1 and 3 and ≤ 30% of members scored it between 7 and 9. The results of each round of the Delphi survey and members' comments were shared anonymously with the group. When an original term/definition required modification, the members were requested to re‐rate the revised term/definition in a second round of the Delphi survey. When consensus was achieved and a final set of terms and definitions was agreed, the executive group arranged an online meeting of experts to discuss the results.

2.3. Online Meeting

An online meeting was held with those who participated in the Delphi process to discuss the glossary. Prior to the meeting, the draft terms and definitions, the agenda and the results of the online Delphi study were provided. The project leader (HA) presented the results of the Delphi process during the meeting, and members discussed the inclusion, exclusion or refinement of all the terms and definitions.

2.4. Post‐Meeting Activities

In accordance with the discussions that took place during the online meeting, the Executive Group and Task & Finish Group discussed the terms/definitions and made minor modifications to enhance their clarity and accuracy before compiling the final version of the glossary.

3. Results

Thirty‐four individuals accepted the invitation to join the Delphi process, of which 32 completed the questionnaire (94%). Fourteen out of 15 terms received agreement of more than 70% of members, in which 84% of the scores were between 7 and 9 (Table 1). More than 70% of the members agreed on the term pulp chamber ceiling in place of pulp chamber roof, minor and major apical foramen instead of minor and major apical diameter, respectively, and severe root curvature instead of dilaceration (Table 2). Only one term (furcation accessory canal) reached agreement below the necessary 70% for consensus. After revision of the term and definition, a second round of the Delphi survey was performed, with agreement of 88% achieved for the revised term.

TABLE 1.

Scores for the draft terms and definitions resulting from the Delphi survey.

Terms	From 7 to 9	< 7	Percentage agreement
Term 1 (Accessory canal)	27	5	84
Term 2 (Apical delta)	27	5	84
Term 3 (Bifid root)	27	5	84
Term 4 (Canal isthmus)	29	3	91
Term 5 (Chamber accessory canal)	27	5	84
Term 6 (Furcation accessory canal)	22	10	69
Term 7 (Major apical foramen)	28	4	88
Term 8 (Minor apical foramen)	24	8	75
Term 9 (Pulp chamber)	24	8	75
Term 10 (Pulp chamber roof)	28	4	88
Term 11 (Pulp chamber floor)	28	4	88
Term 12 (Pulp horn)	31	1	97
Term 13 (Severe root curvature)	26	6	81
Term 14 (Root fusion)	30	2	94
Term 15 (Transverse canal anastomosis)	28	4	88

TABLE 2.

Results for the agreement of the use of the four new terms suggested in the Delphi process.

Terms	Agree	Disagree	Percentage
Pulp chamber ceiling instead of pulp chamber roof	26	6	81
Minor apical foramen instead of diameter	24	8	75
Major apical foramen instead of diameter	25	7	78
Severe root curvature instead of root dilaceration	25	7	78

A total of 19 individuals joined the online meeting held via Zoom (https://www.zoom.com/) to discuss the results of the Delphi survey and the revised terms and definitions. The Task & Finish Group and Executive Group considered the comments raised, and produced the final version. Table 3 presents the final glossary of terms and definitions.

TABLE 3.

Glossary of terms and definitions in root and canal anatomy.

Term	Definition
Accessory canal	A small canal that branches off from (leaves) the main root canal(s) or pulp chamber and most often opens onto the root surface (patent), though it may appear to be blind (no obvious connection with the external root surface) or looped (branches from and ends in the main canal).
Apical delta	A complex network of three or more accessory canals branching from (leaving) the main root canal with most opening onto the root surface near the root apex, though some may be blind or looped.
Bifid root	A single root that splits into two anywhere in the apical half of the apical third of the root.
Canal isthmus	A flattened passage that usually connects two (or more) separate root canals within a root.
Chamber accessory canal	An accessory canal that originates from the pulp chamber floor and opens onto the root surface toward the furcation in multi‐rooted teeth (patent), though it may be blind (a) or looped (b).
Accessory furcation canal	An accessory canal that branches from (leaves) the main canal and opens in the root surface in the furcation region in multi‐rooted teeth.
Major apical foramen	The opening of the main canal on the external surface of a root.
Minor apical foramen	The narrowest portion of the root canal in the apical region corresponding to the canal terminus that usually lies a short distance from the major apical foramen.
Pulp chamber	The central pulp space within the crown portion of the tooth that can extend into the root trunk (in multi‐rooted teeth) apical to the cemento‐enamel junction.
Pulp chamber ceiling	The superior coronal surface of the pulp chamber.
Pulp chamber floor	The inferior surface of the pulp chamber, situated at the level of the cemento‐enamel junction or more apically in the root trunk in multi‐rooted teeth.
Pulp horn	A coronal projection of the pulp space within the ceiling of the pulp chamber that normally correspond to a major cusp or lobe of the crown.
Severe root curvature	A severe bend (90° or greater, often with a small radius of curvature) of a root along its axis.
Root fusion	The union between two or more separate roots in a tooth. Root fusion can occur along part or the entire length of roots and involve dentine and cementum or cementum only.
Transverse canal anastomosis	A minor accessory connection(s) between separate canals within a root.

Source: The figures used in this table are reproduced with permission from Ahmed (2022), Ahmed et al. (2021, 2024, 2025) and Al‐Rammahi et al. (2025).

4. Discussion

This paper introduces a consensus‐based glossary of controversial terms and definitions related to root and canal anatomy that were identified in a previous publication (Ahmed et al. 2024). The glossary was developed following a validated and standard methodology using a Delphi survey and online meeting to arrive at a global consensus. A Delphi process is a non‐random sampling method that involves the recruitment of a panel of experts to obtain high‐quality responses (Shang 2023). The criteria used to define an ‘expert’ are diverse, and in this study, the authors followed the commonly accepted requirements for participation in the panel, including experience and knowledge in root and canal anatomy, willingness, capacity and time to participate, and adequate communication skills (Trevelyan and Robinson 2015; Shang 2023). The Executive Group together with the Task & Finish group invited members from different continents to achieve a global agreement.

There is no universal standard for the size of a Delphi panel, and they are frequently tailored to the specificity of the research aim, time and available resources (Shang 2023). One report found that 23 participants in a well‐defined knowledge area led to response stability within multiple rounds (Akins et al. 2005). By engaging 32 experts, the present study exceeded that threshold and maintained consistency with other Delphi studies published in medicine and dentistry (Weir et al. 2015; Mac Giolla Phadraig et al. 2024).

4.1. Terms Related to Root Anatomy

The term ‘Bifid root’ and its proposed definition received similar agreement scores to the other terms; however, several members raised concerns over its clinical relevance. Bifid roots complicate canal preparation and root‐end surgery, and therefore have an impact on the clinical approach adopted. A bifurcation is also associated with an increased number of accessory canals in the apical third (Keleş et al. 2020), which requires a specific approach to canal preparation and filling.

The proposed definition for the term ‘Root fusion’ has taken into account the wide morphological variations of this anatomical feature, together with the fact that roots may fuse as a result of either the failure of Hertwig's epithelial sheath to develop, fuse in the furcation area or be the result of coalescence owing to cementum deposition over time (Manning 1990; Gao et al. 2006). It is important to recognise that root fusion can affect the internal root canal anatomy. For example, fused roots with complex internal anatomy have a higher frequency of merged canals, isthmi and C‐shaped root canals (Marcano‐Caldera et al. 2019).

Historically, several definitions have been used to describe the term ‘Root dilaceration’. Some have defined a dilaceration as a 90° angle or greater along the axis of the tooth or root (Hamasha et al. 2002), whereas others defined it as a deviation from the normal axis of the tooth of 20° or more in the apical part of the root (Chohayeb 1983). In an Oral Biology textbook, dilaceration was defined as a severe bend or angular distortion of a tooth root without referring to a specific angle (Sheid and Weiss 2012). In essence, a dilaceration describes a severe bend or angular distortion of a root along its axis, usually at a 90° angle or greater, often resulting from trauma during tooth development. The term dilaceration is derived from the Latin word ‘dilacerare’, which means ‘to tear apart’. This tearing apart is not relevant for most teeth, and 78% of the Delphi members concluded that the term should not be used. Rather, the term ‘severe root curvature’ was selected in place of dilaceration.

4.2. Terms Related to Pulp Chamber Anatomy

This report identified three terms that describe pulp chamber anatomy (pulp chamber, pulp chamber floor and pulp horns), and also suggested the replacement of one term ‘Pulp chamber roof’ with ‘Pulp chamber ceiling’, which was agreed by more than 80% of the Delphi panel. The term ‘ceiling’ was suggested to replace ‘roof’ as it refers to the internal superior surface of a pulp chamber, whereas ‘roof’ refers to the external outer surface (of a building, for example). Defining the apical extent of the pulp chamber (pulp chamber floor) in multi‐rooted teeth is controversial because the CEJ is not usually at the level of the floor of the pulp chamber (Ahmed et al. 2024), which is more often located some distance apical to the CEJ and within the root trunk (Nelson and Ash 2010; Ahmed et al. 2025).

4.3. Terms Related to Root Canal Anatomy

Historically, the terms ‘transverse canal anastomosis’ and ‘canal isthmus’ have been used interchangeably and refer to a narrow communication between two or more canals in the same root or between vascular elements in tissues (AAE 2020; Ordinola‐Zapata et al. 2019; Natanasabapathy et al. 2021). This has caused inconsistencies in reporting among studies as discussed in a recent review (Ahmed et al. 2024). In this glossary, the two terms were defined as distinct individual anatomical features to reflect their unique morphology, with both terms receiving agreement of approximately 90%.

The definition of the term ‘Accessory canal’ achieved a global agreement of 84% (score ≥ 7), which reflects substantial agreement on the clarity of the term and definition. However, several members raised concerns about the criteria for loop and blind accessory canals and whether they should be included in the definition, particularly since they do not have obvious communications with the external root surface. In addition, blind canals may reflect micro‐CT resolution limits or reconstruction artefacts rather than a true anatomical landmark. Though there is evidence for their existence in samples examined under standard scanning parameters (Ahmed et al. 2025; Aljawhar et al. 2025), such anatomical features require further investigation. Although this fine anatomy is unlikely to have direct clinical relevance, such anatomical features explain the diversity in accessory canal types and the different communication pathways between the main canal and external root surface. The term ‘Apical delta’ received a similar score to the term ‘Accessory canal’. The proposed definition for apical delta is consistent with previous reports (Cheung et al. 2007; Gao et al. 2016); however, for clarity, the definition specifies three or more accessory canals for consistent usage.

While the term ‘Chamber accessory canal’ received substantial agreement (84%), the term ‘Furcation accessory canal’ received < 70% agreement with the score of ≥ 7. Several members believed that both terms overlapped, and some felt that the latter term was confusing and required clarification. Therefore, the term was revised and discussed further in the online meeting. For simplicity, the blind and loop types of accessory canals were removed from the definition of an ‘Accessory furcation canal’ since it is challenging to define their relationship to the furcation region, which is more distinguishable when the accessory canal originates from the pulp chamber (Table 2). The word ‘region’ was also added to ‘furcation’ as described previously by Sheid and Weiss (2012). It is important to emphasise that the furcation region can occur along the entire root, which is the main difference from chamber accessory canals as shown in the examples in Table 2.

Understanding the morphological features of root apex anatomy using accurate, consistent terminology is important since the various landmarks are involved in (or in close relation to) each step of root canal treatment (Hülsmann and Schäfer 2009; Plotino et al. 2020). Over the years, several terms have been used interchangeably to define the narrowest apical canal opening (which for many clinicians represents the apical limit of root canal treatment procedures) such as apical constriction, minor (apical) foramen, minor (apical) diameter and physiological foramen (Ahmed et al. 2024). This consensus‐based survey has suggested the replacement of the term ‘Minor apical diameter’ with ‘Minor apical foramen’ since the smallest canal diameter on longitudinal sections of roots (or on 2D radiographic images) does not necessarily correspond to the smallest cross‐sectional area of the root canal when measured in axial sections of micro‐CT scanned teeth (ElAyouti et al. 2014; Schell et al. 2017; Ahmed et al. 2024). This was agreed by 75% of members with the major apical foramen also receiving a similar percentage agreement.

In summary, this report represents a step towards establishing consistent and standardised terminology for root and canal anatomy across education, research and clinical practice. The consensus‐based glossary provides a structured framework for the precise conceptualisation, description and differentiation of anatomical landmarks of teeth, roots, pulp chambers and root canal systems. By creating and promoting uniform terminology, this initiative will facilitate accurate and consistent comparison between studies, enhance communication among stakeholders and support reproducibility in research. Although some of the existing terms and definitions have been used for a long time (such as pulp chamber roof and root dilaceration), in the context of the rapidly expanding body of knowledge in dental anatomy, the adoption of accurate, consistent terms and clearly defined concepts is essential to ensure effective knowledge translation and reliable clinical application.

5. Conclusions

This paper presents a consensus‐based glossary of controversial terms in root and canal anatomy, developed through a rigorous and validated process. The universal consensus achieved provides a robust foundation for the adoption of the precise and standardised terms and definitions derived from the process that will be applicable across education, research and clinical practice. Establishing and implementing consistent terminology will reduce ambiguity, minimise misinterpretation and prevent inaccurate comparisons within and between laboratory and clinical studies. Accordingly, this consensus represents an important step towards enhancing clarity, consistency and scientific rigour in the communication and application of root and canal anatomy.

Author Contributions

Each author made substantial contributions to the design of the study and the manuscript. All authors read and approved the final version of the manuscript.

Ethics Statement

Ethical approval was obtained from the Medical Ethics Committee, Faculty of Dentistry, Unversiti Malaya [DF RD2524/00104 (L)].

Conflicts of Interest

The authors declare no conflicts of interest.

Ahmed, H. M. A. , Nagendrababu V., Keleş A., et al. 2026. “A Consensus‐Based Glossary for Controversial Terminology in Root and Canal Anatomy.” International Endodontic Journal 59, no. 11: 2436–2447. 10.1111/iej.70225.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.