Get Smart – technological innovations in endodontics part 2: case-difficulty assessment and future perspectives

Case-difficulty assessment tools

Endodontic treatment, like any healthcare procedure, is not risk-free. Inadequate instrumentation, insufficient disinfection and incomplete obturation of the root canal system may result in an unfavourable treatment outcome and persistence of disease. In addition, during delivery of endodontic treatment, instrument separation, perforation and other procedural errors may occur resulting in the need for re-treatment or even tooth loss.^6,7,8,9,10 Such procedural errors may be influenced by the level of operator knowledge, skill and experience in managing variables in patient- and treatment-related prognostic factors.^{11,12,13,14,15,16}

A recent study investigated the influence of case complexity on endodontic mishaps for undergraduate students using hand files or reciprocating engine-driven files and found that 31.9% of instrumented teeth had at least one procedural error, including over-instrumentation, loss of working length, short obturations, long obturations, canal transportation, instrument separation and strip perforations.¹⁷ There was a correlation between multiple endodontic mishaps and a high level of case complexity, irrespective of the instrumentation method (hand- or engine-driven). Thus, the level of difficulty was more important than the instrumentation method in determining the occurrence and frequency of endodontic mishaps. This reconfirmed that there may be a greater risk of procedural errors even when endodontic treatment challenges do match the operator's capabilities. Endodontic treatment, especially where challenging, may understandably be beyond the skill and experience of some operators.

The GDC's ‘Moving Upstream’,¹⁸ highlighted the ‘climate of fear’ faced by dental students and newly qualified dentists commencing their career, induced by pressures of patient complaints, litigation and the threat of the regulator. Against this background, not just the newly qualified, but every member of the dental team would benefit from assistance in assessing case complexity. Therefore, if there is a tool available to help assess the risks and difficulties of a particular case, the operator can then decide whether to undertake the treatment or, if necessary, refer it onwards for specialist management. When a case is correctly assessed and appropriately managed, it is more likely to lead to a favourable treatment outcome, and reduce the need for treatment revision, or even tooth loss. This translates into savings in terms of financial outlay, pain and suffering for patients.

Ree et al¹⁹ noted that general dental practitioners must be capable of determining the complexity of endodontic treatment and, to be able to refer patients onwards for management, specialist services must also be available. In the UK, despite the recognition of endodontics as a specialty, there are insufficient specialists to service the increasing endodontic treatment demands of patients. In an attempt to address the issue, the concept of dentists with extended skills/special interest in endodontics came into being. Dentists with extended skills/special interest in endodontics are general dental practitioners who have chosen to receive further training to provide enhanced endodontic services.^20,21 Therefore, within the limits of their competency, they can accept referrals from dental colleagues, treat moderately complex cases, and refer more complicated cases for specialist management.²¹ However, any solution to meet the increasing number of endodontic treatment demands is still reliant on accurate determination of treatment complexity, to ensure an individual case is managed by an operator with the appropriate skill-set.

Web-based tools

Case-difficulty assessment tools can assist in determining the complexity of endodontic treatment through a cumulative and systematic risk analysis of important clinical and radiographic criteria, and their variables. Examples of case-difficulty assessment systems and forms include the following:

Although these systems and forms were designed to help ascertain the level of difficulty for individual cases and to suggest appropriate treatment delivery pathways, they have limitations. For example, reliance on a manual scoring system, terminology variances, and limited country-specific relevance regarding triage systems and referral pathways.²⁶

These limitations led to the development of a web-based, digital tool for case-difficulty assessment, EndoApp (Figure 1), which uses an automated scoring system, and generates score-based and relevant referral pathways recommendations depending on complexity level.²⁶ Research on EndoApp has been carried out to assess usage times, user experience and relevance using simulated cases. The results showed that the average usage time was 67 seconds, demonstrating its efficiency, and the majority of users expressed favourable views on their user experience and the app's relevance.²⁶ The potential application as an ‘educational tool’ and for ‘primary care triage’ were deemed the most popular features. Positive comments focused on its simplicity, ease of use, practicality, and comprehensiveness. Whereas comments and suggestions for improvement were aimed at refining the scoring system, modifying the flow structure, and incorporating additional features to manage referrals and record-keeping.

Based on the above, a multi-centre study, comparing the educational potential of EndoApp and the AAE case-difficulty assessment form, was carried out on dental undergraduate students (n=206) from four dental schools.²⁷ The participants' knowledge reinforcement regarding critical non-surgical root canal treatment complexity factors, agreement with the recommendation generated on management pathway, and preference were investigated.²⁷ The results showed a clear preference for EndoApp (65%) compared with the AAE form (11%).²⁷ Both methods demonstrated a significant increase in knowledge reinforcement; however, a greater level of agreement with the recommendation generated was reached with EndoApp than with the AAE form.²⁷ Thus, for dental education purposes, EndoApp can help undergraduate dental students develop a better understanding of technical challenges in endodontics, such as complex root canal anatomy and treatment limitations, and improve decision-making skills for treatment planning. As a clinical teaching aid, EndoApp can be used to reinforce practical aspects of endodontic knowledge and nurture skill development.^26,27

Case-difficulty assessment tools also have other uses. In the publicly funded NHS, resources are limited, and an increased number of referrals equates to a corresponding pressure on secondary and tertiary care providers.^28,29 Hence, for best use of resources, it is even more critical to accurately assess referred cases based on care-acceptance criteria and treatment urgency. Unfortunately, triaging still relies primarily on consultant- or specialist-grade staff going through each received referral, often on paper. Additionally, efforts to mitigate excessive demand for secondary and tertiary NHS care services has led to the development of a three-tier complexity classification system.^21,30 Insufficient clarity, and a lack of consideration for compounding and risk factors, and/or inadequate comprehensiveness may also result in cases being wrongly assigned, for example, where a non-specialist struggles to manage a highly complex case, which was initially considered to be relatively easy. The use of EndoApp for digital triaging could help to overcome such issues. The criteria for acceptance can be tailored according to care service availability and competency, and incorporated into EndoApp's algorithm. Referral triaging could then become automated, and the reliance on consultant- or specialist-grade staff input would no longer be essential. There would also be no delay in being advised whether the referral would be accepted for further assessment and, hopefully, treatment. It is envisaged that general dental practitioners wishing to refer an endodontic case could directly access a secure online portal to use EndoApp and upload any relevant images of the case. The automated process generates the appropriate response, without unnecessary delay and providing there is linkage between systems, appointments and treatment could be offered. There is also the potential, through machine learning for such a triaging system to become ‘smarter’. Therefore, EndoApp has the potential to help deliver more cost-efficient and seamless endodontic care services at all levels through accurate assessment, speedy filtration and appropriate diversion of referrals.²⁶ This would also help reduce overall waiting times and unnecessary distress for patients.

As a case-difficulty assessment tool, EndoApp could also have a role in overall dento-legal risk management. Currently in the UK, there are no restrictions on the type or level of difficulty of cases dentists can undertake. However, this may change considering the unremitting and exponential increase in dental litigation.³¹ The GDC has published guidance on scope of practice³² and the standards expected³³ from dental professionals. Core ethical principles that a GDC-registered dental professional must uphold at all times include:

EndoApp can help dentists to uphold these core ethical principles by assisting in the determination of case complexity and sign-posting the likely challenges for an individual case. Dentists can then practise within the limits of their individual competences and abilities, and, where necessary, refer cases onwards for management, thereby working in collaboration with colleagues and putting patients' interests first.

With the ubiquitous availability of mobile internet services and the popularity of smartphone and related devices, a smartphone version of EndoApp is under development.^26,27 This version would provide a simple, quick and interactive questionnaire, automatically deducing the level of difficulty, and generating corresponding recommendations. It would be a more practical, user-friendly application and, potentially, revolutionize endodontic case-difficulty assessment.

The app would be capable of operating across multiple platforms and devices, facilitating paperless access, and be more easily distributed, maintained and updated. Planned functionality improvements include automatic determination of the angle of root curvatures and lengths and linkage to location-based referral services – potentially providing a seamless pathway from assessment to referral. Furthermore, artificial intelligence integration is planned to permit various automated features, including deep analysis of radiographic images for detection of root canal outlines, quantity and quality of root-fillings, type of coronal restoration, intelligent management of referrals and related correspondence, and treatment-outcome monitoring.

Future perspectives

‘Prediction is very difficult, especially about the future’ is a quote attributed to Niels Bohr, the Danish physicist and Nobel Prize winner. Nevertheless, further technological developments are on the horizon and innovations based on, for example, virtual, augmented and mixed reality, artificial intelligence and robotics are anticipated. They all have potential applications in endodontics.

Virtual, augmented and mixed-reality endodontics

There are differences between virtual, augmented and mixed reality.³⁴ Virtual reality (VR) is a fully immersive virtual-only experience. All visual input from the surrounding environment is blocked out, and the ‘real world’ is shut out altogether. It has been used, for example, in simulation-based training. Augmented reality (AR) overlays real-world content with computer-generated content. This superimposed digital overlay can only interact superficially in real-time with the surrounding environment; for example, viewing a patient's laboratory results or scans while operating. Mixed reality (MR) projects spatially aware and responsive 3D digital content that interacts with the surrounding environment. With MR, virtual objects become part of, and interact with, the real world. For example, superimposing scans can be superimposed onto a patient's body during surgery, and similarly, this could be applied to endodontics (Figure 2).

In dentistry, AR in implant surgery was investigated using a video projector system, synchronized with a dynamic implant guidance system, to accurately overlay 3D radiographic images over the surgical site.³⁵ The high precision was verified by simulating implant osteotomies on plaster models before using the technique on a volunteer patient. The position and movements of the patient were constantly tracked using an optical camera and matched with the projected image using tracking markers attached to the teeth.

In a later study,³⁶ motion parallax of the patient with the 3D radiographic image projection was maintained using the contours of the teeth as references and tracking markers. This AR technique permits accurate visualization and direct guidance, without reliance on computer display monitors. However, at the time of writing, the equipment may be too cumbersome for everyday clinical practice. Other AR techniques, which use head-mounted stereo video devices, or the projection of high-intensity guidance light beams, have been described for use in oral and maxillofacial, implant, and trauma surgery, to improve accuracy of surgery and/or visualization of hidden anatomical structures.^37,38,39

In non-surgical root canal treatment, software for use with AR has already been investigated for real-time automated canal location.⁴⁰ This software relied on images obtained from a camera and algorithms encoding the ‘laws of pulp chamber anatomy’⁴¹ for canal location. However, 2D images were still used, which change with different camera angles, resulting in difficulties in accurately detecting pulp chamber anatomy. Furthermore, extensive coronal destruction was required to prepare access cavities in order to permit capture of pulp floor features in their entirety. This problem may be overcome using AR technology with matched 3D imaging data, which offers the possibility of pre-operative canal location planning, thereby minimizing the unnecessary loss of tooth tissue.

For apical surgery, the identification of surgical landmarks and real-time monitoring of surgical instruments may be used for educational and clinical training purposes. Such guidance systems might be useful for flap design, creating precise osteotomies and root-end resections, especially in cases where the root-end is in close approximation to critical anatomical structures. Another possibility is the integration of AR with the dental operating microscope⁴² enabling some form of data overlay system rather than images being displayed on a computer monitor. This would allow for direct visualization, reducing the risk of mishaps without compromising accuracy when executing procedures.

There are many AR and MR consumer technology devices under development. These are increasingly being adapted for healthcare use.^43,44 Treatment planned on a virtual patient and based on 3D imaging data can be directly projected or superimposed onto the patient to provide guidance on operative procedures. The first-ever globally live-streamed surgical procedure was conducted using Google Glass, an AR system developed by Google (Alphabet Inc, Mountain View, CA, USA).⁴⁵

Based on a similar concept for application in endodontics, 3D imaging data acquired from a CBCT scan and the resultant treatment plan may be overlaid onto a tooth. Advanced light-weight hologram lenses that support MR (eg Microsoft's HoloLens 2; Microsoft, Redmond, WA, USA; Figure 3) may provide an untethered solution for visualizing superimposed 3D holographic anatomy and pre-planned guidance to allow easy and intuitive interaction to dynamically guide non-surgical root canal treatment and apical surgery.

Complicated cases requiring non-surgical root canal treatment or apical surgery are more routinely encountered in specialist practices. They can be challenging for most operators, and are less frequently performed in public health service systems such as the NHS.¹² Furthermore, a reduction in the frequency of apical surgery, due to successful management by non-surgical re-treatment approaches, increased tooth replacement with implants, and a rise in dento-legal litigation^46,47,48 may contribute to operator skill erosion and insufficient training opportunities.⁴⁹ Therefore, an MR device may also benefit the practitioner's skill and learning needs. Connectivity and portability of these devices, and wide availability of peripheral devices (such as smart phones and tablets) may also permit effective distance-learning and mentoring.

Artificial intelligence, robotics and tele-endodontics

Artificial intelligence (AI), by mimicking human cognitive function, allows machines to learn. By accurately interpreting cumulative learning, AI machines can flexibly adapt and be used to perform specific tasks, for example, dental charting,^50,51 caries detection,⁵² and bone loss.⁵³ In endodontics, a recent study demonstrated the high reliability of AI in the detection of periapical lesions on CBCT images compared to human observation.⁵⁴ Machine learning is an application of AI in which computer systems can access data and automatically learn and improve from experience without being explicitly programmed. When incorporated into a digital case-difficulty assessment tool, such as EndoApp, machine learning will enable it to be refined, becoming increasingly more accurate and efficient.

Robotics, technology in which machines are designed and used to undertake precise, repetitive and pre-set procedures, have been hailed as the next Industrial Revolution. In medicine, the extent of the uptake of robotics has been unprecedented, with many surgical specialties adopting the technology.^55,56

Advances in AI and robotics have, therefore, the potential to lead to the development of automated systems capable of analysing the complexity of non-surgical root canal treatments, planning the treatment independently or interactively, and performing the labour-intensive treatment stages, such as access cavity preparation, chemo-mechanical preparation and/or disinfection, or the complete treatment. This may help reduce excessive loss of tooth structure,⁵⁷ optimize the shaping and disinfection of the root canal system, and limit procedural errors, such as instrument separation, canal ledging and transportation, root perforation and debris extrusion.

Telemedicine can be defined as ‘the delivery of healthcare services, where distance is a critical factor, by all healthcare professionals using information and communication technologies for the exchange of valid information for diagnosis, treatment and prevention of disease and injuries, research and evaluation, and for the continuing education of health care providers, all in the interests of advancing the health of individuals and their communities'.⁵⁸ The convergence of complimentary digital technologies may see the emergence of telemedicine concepts being applied to endodontics, whereby an endodontist using video-conferencing technology plans and guides an online-connected robotic system to perform the treatment remotely. The implications of such a convergence include improved availability of endodontic services, regardless of location, and all patients could receive similar access and levels of care. Such a convergence would also have valuable applications in dental education, training and continual professional development.

Although attempts have been made to develop robotic technology in endodontics,⁵⁷ variations in treatment complexity and patient factors are, presently, major technical challenges to overcome. Further investment, research and development is needed to realize the ambition of introducing robotics into everyday endodontic practice.

Conclusions

Technological advances have permeated every aspect of society. Judiciously adopted and appropriately used in patient-centred healthcare, they have the potential to change lives. The selected technological innovations in endodontics that have been described can contribute and facilitate the assessment, management and treatment of challenging endodontic cases in clinical practice; ultimately improving treatment outcomes and patient care.