Until recently, caries lesions were managed by the conventional “drill and fill” philosophy, meaning complete carious tissue removal and the replacement of missing tooth tissue with a restoration. This operative or surgical approach to dental care, where all carious tooth tissue is removed as a standard part of the procedure to manage the carious tooth, is no longer advocated.^1,2

More modern and evidence-based approaches to managing lesions involve selectively removing carious tissue from a cavity and sometimes not removing any of the carious tooth tissue at all, before making a decision about how to restore the missing tooth substance. These approaches promote the preservation of tooth structure and the health of the dental pulp, and minimize intervention. However, they must be applied alongside activities aimed at preventing further disease. These activities focus on efforts to modify behaviors that led to the disease in the first place or supported factors leading to the disease (ie, inadequate biofilm removal, remineralization, or high sugar consumption). Methods like this to prevent the establishment of caries lesions can also be used to prevent progression of the disease and, therefore, stop its consequences. This can be especially useful in primary teeth, which are shed.

What is nonrestorative cavity control?

NRCC is a single term used to describe a philosophy of treatment that comprises multiple stages and approaches. The choice of these depends on the lesion extension, location, and activity, and requires understanding the patient and their family rather than being a single procedure with prescribed linear steps. An active decision is made to arrest a single lesion, or multiple lesions in a child’s mouth, rather than to restore. This is done by making the lesion into a cleansable shape by the clinician, regular biofilm removal by the patient and/or carer, and remineralization usually through fluoride-based products applied by the clinician or in toothpaste.³

Natural history of dental caries

The natural history of a disease describes how it progresses in an individual over time, without intervention. The common model of disease progression suggests that it will either result in: (1) full resolution with recovery; (2) resolution but leaving some disability or, in the case of dental caries, tooth destruction; or (3) continue to progress, in the case of dental caries, until loss of the affected tooth/teeth. Although there is some variability between patients with regards to the rate of progression, a proceeding caries lesion will start with a subclinical presentation then become detectable with visual and/or tactile investigation. Next there will be tissue destruction leading to cavitation, potentially reversible then irreversible inflammation and infection of the dental pulp with eventual bone infection, and ultimately loss of the tooth. However, it is not inevitable that the disease will always continue to progress through these stages. Nor is it inevitable that there will ultimately be loss of the tooth. This is because the factors leading to the initiation and progression of the disease change as the disease progresses.

In young permanent teeth, lesions that are confined to enamel only progress at a rate of around 3.9 years (per 100 surfaces at risk) to reach at least the inner half of enamel,⁴ and the annual rate is 5.4 years from the inner half of the enamel to the outer half of the dentin. However, in primary teeth enamel lesions progress to dentin more quickly, at a rate of around 2.5 years.⁵ Dental practitioners are motivated to interfere in this process to stop the lesion progressing and improve outcomes for the patient. However, we do not often consider what would happen if we did not interfere in the disease process. Sometimes, the disease can stop because the circumstances that caused it or the environment the tooth is in has changed. Also, in the case of primary teeth, the teeth may be shed before they give the patient any problems. It is therefore not always necessary (or possible) to manage the lesion by restoring it. Less invasive treatment approaches like NRCC can be used.

Prevention as a desirable approach to managing dental caries

Prevention has traditionally been thought of as having three categories or layers:

• primary prevention – the actions taken to ensure that a disease does not occur
• secondary prevention – actions that reduce the impact of a disease or injury after it has already occurred
• tertiary prevention – actions to reduce the impact of an ongoing illness or injury that has lasting effects.

However, more recently there have been moves to include a fourth layer: quaternary prevention, essentially a concept that aims primarily to ensure patients are not overmedicalized or exposed to unnecessary risk associated with medical activities.^6,7 This approach can be related to the disease dental caries and improving its management (Table 14-1).⁸

Table 14-1 Levels of preventive care and examples related to dental caries

Historical management of caries lesions

Since the beginning of dental surgery, and until recently, when a caries lesion (even when confined to enamel) or dentinal cavity was seen, dental practitioners would completely remove the carious tooth tissue to the extent that only hard dentin was left in all parts of the cavity (cavity walls and pulpally). They would then place a filling. This used to be known as complete caries removal but now tends to be called “non-selective caries removal.”

Caries used to be considered an infectious disease caused by microorganisms that needed to be fully eliminated from the lesion. In contrast to this, the current concept of the pathophysiology of dental caries defines it as a process, which occurs in the biofilm, leading to an imbalance in the equilibrium between tooth mineral and biofilm fluids. The biofilm is always metabolically active, with constant fluctuations in pH. The result may be a net loss of mineral, leading to the symptom of the disease, the manifest caries lesion. However, when re-deposition of mineral dominates and lesion environmental conditions change, the result can be that the lesion’s progression halts.^10,11 Over the last four decades, diverse studies including ones placing fissure sealants over carious dentin,¹² some involving selective (one-step) and stepwise excavation and restoration,¹³ and others involving no caries removal,^13,14 suggest that caries lesions can be arrested provided that clinically biofilm-free/biofilm disturbance conditions are maintained.¹⁵ Thus, the contemporary aim of treating caries lesions focuses on controlling the lesions’ activity, while preserving tooth tissue and pulp vitality. Even those lesions into dentin can be managed by changing the biologic conditions causing the imbalance (mainly by manipulating the biofilm) or simply sealing over them with materials whether this is on the occlusal or the proximal surface.^13,14,16,17

Is restorative management always necessary or possible?

The main reason for placing a restoration is to aid biofilm control, protect the pulp, and restore the function, form, and esthetics of the affected tooth.¹⁸ Cavitated dentinal caries lesions have been traditionally restored with filling materials. However, in those lesions, biofilm control and remineralization can be enough to control the disease process. Cavitated lesions that are accessible to visual-tactile examination are potentially cleansable lesions or can often be converted into cleansable lesions by widening the lesion opening. The lesion can then be arrested by continual plaque disruption/cleaning. In those cases, the need for restorative treatment is questioned.^19,20

In addition, it is not always possible to restore some lesions/teeth. There can be too much tooth tissue loss to place or retain a restoration, or the lesion may have extended subgingivally and moisture control cannot be achieved. Despite such extensive lesions, there are often no signs of infection such as periradicular pathology on radiographs or soft tissue signs of infection, and the patient has no pain (Fig 14-1). The pulp responds to the advancing lesion by laying down reactionary dentin, and the coronal pulp becomes much smaller than it was originally. Although the lesion looks as though it should have encroached upon the pulp from a clinical perspective, often it has still not directly reached it. Of course, some of the proteolytic enzymes, acids, and bacteria may still have entered the dentinal tubules and the pulp may be inflamed in reaction to this. However, the pulp may not be irreversibly damaged, and with removal of the factors causing inflammation, through brushing the biofilm away, and by causing no further inflammation through treatment, the pulpal inflammation can reduce.

In these cases, it is difficult to justify extracting the tooth as the patient gains no benefit. In fact, it can be detrimental to do so as this can lead to treatment-induced anxiety and may also result in loss of space as the remaining teeth can move into the space.

How to carry out NRCC

When the active decision has been made to arrest a single lesion, or multiple lesions, in a child’s mouth by constant biofilm removal (by the patient/carer) and remineralization, rather than to restore the lesion, it is very important that a baseline record of the status of the tooth/lesion is taken at that point. This can be written, photographs, or using an index such as the International Caries Detection and Assessment System (ICDAS),²¹ and should include the size and depth of the lesion and whether it is active or arrested (partially or completely). The caries lesion(s) is(are) made accessible to a toothbrush or additional cleansing device. This can be done by rotary instrumentation or hand removal (chiseling) of overhanging enamel (Fig 14-2). Arresting the lesion must be supported by applying sodium fluoride varnish or silver diammine fluoride (SDF) solutions. Lesions are repeatedly monitored over time for progression and a record made of the success or failure of the NRCC approach, with the clinician always considering changing the treatment plan if it looks like this approach is not working.

The potential of SDF in caries prevention and arrest of dentin caries lesions in the primary dentition has already been demonstrated in various randomized clinical trials and presented in reviews.^22–24 This topic is discussed in detail in Chapter 12.

What is the aim of NRCC?

NRCC aims to manage the carious process until a primary tooth exfoliates by using techniques at both a tooth and a person level to preserve the dental hard tissue and avoid initiation of the restorative cycle. Specifically, the aims are to:

• avoid pain and infection from the tooth before exfoliation
• inactivate or control the disease process in caries lesions by promoting tooth brushing and fluoride use at a person level
• preserve the dental hard tissues
• avoid initiating the cycle of restoration
• preserve the tooth for as long as possible
• prevent new caries lesions
• support the child in the dental setting by building their capacity and confidence in accepting dental care
• support the family in adopting long-term oral hygiene habits that promote lifelong dental health.

For which patients is NRCC indicated?

NRCC is particularly indicated for children who have active dentinal caries lesions in the primary dentition. In addition, it can be used to control the disease process, in order to control cavitated lesions that are considered inactive but due to their location or morphology have the risk of becoming active. Furthermore, NRCC is especially suitable for managing caries lesions in anxious children, and very useful as a treatment option for cooperation improvement and building a child’s confidence with the treatment. Detailed indications, contraindications, advantages, and disadvantages of NRCC are presented in Table 14-2.

Table 14-2 Detailed indications, contraindications, advantages, and disadvantages of NRCC for primary teeth by tooth and person level factors

NRCC technique

NRCC is a form of quaternary prevention. It is essential that the parent/carer is in agreement with the approach as they have a crucial role. The treatment option should be discussed in depth with the parent/carer. If agreed upon, it is essential that they, and the child, understand that they are entering into a contract to play their part in stopping the progression of the lesion. This first role is critical to the success of the method. This partnership approach and the important role of the parent contrasts with conventional restorative treatment where the responsibility for success is considered to lie mainly with the dental practitioner. In the NRCC treatment, success depends mostly on parental cooperation, as parents are responsible for brushing the caries lesions.

NRCC demands specific measures to manage the caries lesions:

• obtaining informed consent and agreement to cooperate in their role, from parent/carer
• taking photographs at baseline and follow-up appointments to record and assess the status of the lesion; if this is not possible, there should be a written record of the status of the lesion (eg, using ICDAS)
• making the caries lesions at the cavity level cleansable and accessible for biofilm removal (Figs 14-3a and b)
• applying anticariogenic agents such as fluoride varnish or SDF to optimize success of lesion arrest and prevention of lesion progression
• involving the parent in a comprehensive caries control program involving: behavior change, training in biofilm control, diet instructions, fluoride use, daily brushing of the opened teeth, ie perpendicular to the dental arch (Fig 14-3c) twice daily using fluoride-containing toothpaste (≥ 1,000 ppm F)
• setting regular recall visits allowing lesion activity to be monitored: assessment of the lesion extension (enamel/dentin) and caries activity assessment (active/inactive).

The main characteristics of active and inactive lesions are presented in Table 14-3. In addition, it is essential to reinforce and maintain motivation in the parent/carer to brush the lesion(s). The requirements for success when using NRCC are presented in Table 14-4.

Table 14-3 Characteristics of lesion activity (active/inactive) based on ICDAS-II classifications^25,26

Table 14-4 The requirements for success when using NRCC for tooth/cavity, parent, and clinician level factors

What are the main advantages of NRCC?

The advantage of this cause-related caries management approach is that success or failure can be observed by the activity of the lesion over time and discussed with the child and/or parents/caregiver, perhaps using photographs. The effect of the cause-directed treatment can be clinically evaluated by assessing hardness and shiny appearance of the demineralized tooth surface. The main advantages of this therapy are listed below:

• NRCC has the genuine potential to biologically manage the caries process, preserving dental hard tissue, and avoiding initiation of the restorative cycle.
• NRCC is well accepted by children, parent/carer, and dental practitioner.^27,28
• NRCC can “buy” time for a child to develop the cognition to understand and cope with a more invasive treatment should it be necessary. It also allows time for them to become acclimatized to the dental environment.
• Local anesthesia is not needed and rotary instruments are minimally used; these are two of the most anxiety-provoking stimuli in the dental environment.^29,30

What are the main disadvantages of NRCC?

The main disadvantages of NRCC are the following:

• The pulp may already be irreversibly too damaged to recover.
• Patients (children) cannot carry out the required oral hygiene measures by themselves, so they rely on their parent’s willingness to accept and cope with the treatment.
• There need to be particular circumstances that allow this approach to work – parent/carer (or older children) who are able to accept responsibility for the disease and commit to remedial action including diet modification and regular, frequent tooth brushing with a fluoride toothpaste. It should not be used where an assessment is made that there is no readiness to change behaviors that have led to development of the disease in the first place.
• NRCC might be interpreted as “watchful neglect” by other dental practitioners who might not recognize this as a treatment, so records must be high quality and the parent/carer must be fully informed and “on board.”
• It is very difficult to monitor for success – so photographs might be needed.
• With NRCC the esthetics of teeth will not be restored and it often does not “look nice.”
• NRCC does not always feel satisfying to the clinician or even the parent.
• NRCC involves increased dental visit frequency for lesion(s) follow-up.
• NRCC is not yet considered as a treatment option itself, thus payment will be mostly private or mixed public-private.

Is taking an NRCC approach cost-effective?

The cost-effectiveness of the NRCC approach has been recently compared to other treatment options such as conventional restorations and the Hall Technique for treating asymptomatic carious primary teeth.³¹ Costs were calculated on an existing randomized controlled trial for 2.5 years, and according to the German health care system fees. The NRCC approach was the least cost-effective option, with costs of 296€ compared to 83€ for conventional fillings and 66€ for the Hall Technique. However, the NRCC participants were invited to attend 3-monthly recalls, while participants in the other two groups were seen only twice per year, and the cumulative impact of these visits’ costs was considerable. Further studies should aim to evaluate this in more detail.

Is taking an NRCC approach clinically effective?

Although empirically there is much to support NRCC from a physiologic and pathologic perspective, there is very little evidence from clinical trials of NRCC in comparison to other treatments. This is important because the biologic evidence can tell us much, but without understanding the role that human (patient and clinician) factors play in NRCC, its actual success when applied in the “real world” environment cannot be accurately determined, ie effectiveness vs efficacy.

To date, there is only one randomized controlled trial that has looked at NRCC approaches in a controlled environment, and one longitudinal clinical study of a group of children managed in this way. The first took a patient level approach in a specialist dental hospital environment in Germany.³² The 169 children (3 to 8 years) in the trial were all high caries risk and had asymptomatic proximal cavities in primary molars. Three treatment protocols to manage the cavities were investigated:

• conventional restoration (compomer)
• the Hall Technique
• NRCC.

For NRCC, the dental practitioners improved accessibility of proximal cavities in primary teeth and applied a fluoride varnish (5% NaF). The children’s caregivers were taught how to brush the lesion perpendicular to the dental arch. Fluoride varnish and the instructions were repeated every 3 months. After 2.5 years, 142 children were assessed.³³ Compared to conventional treatment no significant difference was observed in percentage of failures including abscesses, pulpal complaints, or necessity for an endodontic treatment for NRCC, with the rate being 9% for both treatments, although only 2.5% for the Hall Technique. Within the NRCC group, most failures occurred in children not adhering to the 3-month recall interval, indicating that there may have been a lack of commitment or ability to follow the requirements on the parent/carer’s side. Children treated according to the conventional treatment showed less cooperative dental behavior compared to children treated according to the Hall Technique or NRCC.²⁷

A small, uncontrolled study evaluated 30 cavities in the proximal surfaces of primary molars treated with daily site-specific tooth brushing with fluoridated toothpaste and supplemented with professional topical fluoride treatment and dietary advice.³⁴ The treatment was considered unsuccessful if – for a major failure – the child experienced pain and/or the tooth developed pulpal or periapical pathology, or – for a minor failure – the tooth had a filling or sensitivity or lesion progression preventing further adjustment of the lesion margins without promoting biofilm stagnation and food retention. Fifteen of the children were considered to have had successful treatment and 15 were unsuccessful, ie 50% of the children experienced failed treatments with 10 having pain, pulp/periradicular pathology (six were extracted and four untreated) after an average period of 26 months (9 to 44 months). Lesion failure was associated with poor compliance or lesions that were not suitable for the method. However, children and parents were highly satisfied with the treatment, despite the high number of failures in a third (10/30) of the children and pain/infection. In total, 82% of the children pointed to the smiling faces on the visual analog scale, and 95% of parents. The children explained their choice of score with words like: “fun” and “no pain.” The authors concluded that this NRCC treatment can be a helpful method to control caries lesion progression in primary teeth and may familiarize the child with dental treatment.

Thus, although there are reports of success in certain situations, when assessed in dental clinic situations, in the hands of dental practitioners who support this technique, NRCC seems to have a very low clinical success although high parent/child acceptability, and this may limit its applicability to general situations. Overall, the factors need to be understood that promote or inhibit the success of NRCC, and some of these would seem to be closely related to our ability, as clinicians, to change patient behavior.

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