Deep Carious Lesions: Diagnosis, Treatment, and Modern Management Strategies

In the dentistry practice, dentists can encounter restorative challenges related to treating deep carious lesions (DCL). These challenges can be related to achieving the proper diagnosis and sensitivity of the procedure (Schwendicke et al., 2016).

The treatment priorities of  teeth diagnosed with DCL are to maintain vitality of the pulp, preserve the healthy tissue and accomplish a proper restorative seal (Schwendicke et al., 2016). Achieving these goals in the clinical setting can enhance the restorative success (Schwendicke et al., 2016).

Debateble literature exists around the use of different strategies in treating DLC in the primary and permanent teeth, in this paper im going to walk you through the different strategies, recommendations and techniques in order to reach a conclusion.

What is a deep carious lesion (DCL)?

Many clinicians identify the deep carious lesion as a lesions “radiographically extending less than the pulpal third or quarter of dentin” (Schwendicke et al., 2016).Other clinicians identify a DLC when there is less than 1.0 mm of remaining dentin over the pulp (Bjørndal et al., 2017).

However, clinically any cavity that posses the risk of pulpal exposure during excavation should be considered a DCL (Fitzgerald et al., 1990). Therefore, careful diagnosis and identification of the carious lesions is vital for the success of the treatment plan (Fitzgerald et al., 1990).

Diagnosis

Proper diagnosis starts with taking a detailed medical and dental history of the patient, along with clinical and radiographical examination (AAE, 2009). This is important to aid in the diagnosis of the pulpal status and vitality of the tooth/teeth in question before starting the treatment (Aïem et al., 2020). Figure. 1 illustrates different tests that can be taken to determine a pulpal diagnosis.

Figure .1.

Medical History

The clinician must bear in mind any condition that can infleunce the treatment strategy such as patients with previous history of infective endocarditis where it is not recommended to retain an infected tooth that can act as a bacterial niche and can lead to recurrent infection (Brincat et al., 2006). Other scenarios can be patients with medical history of haemophilia where extraction can be contraindicated, and it is more advised to retain the tooth (Dean, 2015).

Chief compliant/History of pain

Actively and carefully keeping records of the history of the chief compliant can, in turn, lead to the correct diagnosis (AAE, 2009). Enquiries should be made regarding the duration of pain, nature, onset and aggravating and relieving factors (AAE, 2009). This is important when for example a child complains of spontaneous pain or inability to sleep at night which can insinuate a diagnosis of irreversible pulpitis (Koch, 2017). However, if the pain was initiated by a stimulus and is of short duration it can refer to reversible pulpitis (Koch, 2017). Some patients can report no pain, which can be in case of a necrotic pulp and chronic abscess and child fails to recall the incidence of pain (Koch, 2017).

The reliability of pulpal diagnosis through history of pain alone in young children is questionable as their concept of pain is still developing (Koch, 2017).

Clinical History

This begins once the patient walks in as you can observe any extra-oral signs such as facial swellings or facial asymmetry which can be because of an acute inflammation and irreversible pulpitis(AAE, 2009).  Secondly, intra-oral examination of the soft and hard tissue is important to look for any draining fistula which suggests chronic inflammation and a necrotic pulp(AAE, 2009).

The clinician must evaluate the mobility and restorability of the tooth, where if there is a significant mobility, he/she must determine whether it’s a physiological root resorption or pathological with consideration to the natural exfoliation time (AAE, 2009).

Pulp tests

Pulp tests such as electric pulp test (EPT) and thermal tests are used as an aid to the diagnosis of the pulp status (Jafarzadeh & Abbott, 2010). These tests are called pulp sensibility tests because they assess the response of the nerves within the pulp, when compared however, the highest accuracy was found for EPT, followed by heat and cold tests (Jafarzadeh & Abbott, 2010).

On the other hand, pulp vitality can be determined by Laser Doppler flowmetry which assesses the vitality of the pulp via blood circulation (Ikawa  et al., 2003).

It was shown that Laser Doppler flowmetry is the sole true indicator of the actual condition of pulp (Ikawa  et al., 2003). In pediatric dentistry pulp sensibility tests have some limitations as the response of the child can be affected drastically by fear and anxiety (Koch, 2017). Additionally, it was reported that false positives can be common in young permanent teeth with  open apexes (Koch, 2017).

Radiographical analysis

Intraoral radiographic assessment evaluates the extent of the carious lesion in terms of decalcification of the hard tissue which can determine possible pulp involvement (AAE, 2009).

Furthermore, clinician must be aware of the condition of the periapical and bifurcation area, therefore, if a tooth was suspected of pulpal involvement, it is advised to take a periapical x-ray rather than bite-wing radiograph (AAE, 2009). Additionally, the clinician must be cautious not to mistake a physiological root resorption with a periapical lesion (McDonald et al., 2011).

Management of Deep Carious lesions

The main goal when treating DCL is to preserve the pulp vitality and prevent further advancement of caries into the pulp (Innes et al., 2016).This is greatly influenced by the amount of excavation of the cavity. Initially the “non-selective approach” was introduced in the 1960’s, this approach focuses on complete caries removal and in case of exposing the pulp, root canal treatment (Innes et al., 2016). The aim of this approach is to excavate the cavity leaving only hard dentin. However, this increases the chances of pulpal exposure as the tissue removed can still undergo remineralization (Innes et al., 2016). Therefore, non-selective caries removal is now considered as an  invasive strategy and overtreatment (Innes et al., 2016). This and with the knowledge that changing the biofilm growth and preventing the nutrient supply from the advancing bacteria can stop the progression of caries led to the development of “Selective caries removal approach” (Innes et al., 2016).

Selective caries removal suggests that soft dentin is left on the pulpal surface to avoid creating stress or possible exposure of the pulp and preparing the cavity at the periphery to hard dentin(Innes et al., 2016). This technique is done to promote pulpal health with maintaining a tight restorative seal (Innes et al., 2016).  When selective excavation and non-selective excavation of deep caries were compared in a randomized clinical trial with a 5-years follow up, Bjørndal et al. (2017) found that selective excavation patients with had less pulpal exposure, less pain and with more vital pulps. Therefore, selective excavation should be regarded as the ideal choice for caries excavation strategy in deep carious lesions (Schwendicke et al., 2016).

To apply caries removal strategies successfully, first we need to know the how to clinically distinguish dentin types, the infected dentin implies for a soft leathery layer that is heavily infected with bacteria and usually superficial to affected dentine, it is also painless and irreversibly denatured (Bjørndal et al., 2017). On the other hand, the affected dentin is a deeper layer harder in consistency and darker in color, it is minimally infected or lack bacteria, reversibly demineralized and tend to be more sensitive (Bjørndal et al., 2017). To provide a guide to differentiate between infected and affected dentin, caries-detection dyes were developed (Yip et al., 1994). However, when studies have shown that these dyes fail to stain the bacteria but rather stain organic matrix that is slightly demineralized.  (Yip et al., 1994). Therefore, utilizing caries detection dyes can lead to excessive healthy tissue removal and  accidental pulpal exposure (Yip et al., 1994). Distinguishing affected and infected dentin is still dependent on the color and texture of the tissue (Fuks et al., 2013).

Mechanism of caries removal

The mechanism of caries removal plays a crucial role in the successful treatment of DCL and prevention of accidental pulpal exposure. For example, utilizing hand instruments like a spoon excavator can allow removal of carious dentin with the advantage of reducing the anxiety because of lack of vibrations as in rotary instruments (Falster et al., 2002). However, at deeper layers excavation with spoon excavator led to increased incidence of mechanical pulp exposure compared to large round burs at low speed. a low-speed handpiece with round carbide burs size 6 or 8 can successfully provide a faster more controlled removal of dentin caries (Falster et al., 2002). Alternatively, when treating uncooperative or anxious child it was suggested that the use of chemomechanical technique such as carisolv can reduce the discomfort of the patient (Fure  et al., 2000). Nevertheless, lack of control over the action of the material over deep caries can lead to increased chances of accidental pulpal exposure (Fure  et al., 2000).

Treatment in primary & permanent teeth.

To understand the treatment options, we must understand morphological and histological differences between the primary and the permanent dentition (Li & Wang, 2002).

The primary teeth in general have a thinner dentin layer and larger pulp chamber than permanent teeth (Li & Wang, 2002). In addition, the primary teeth have lower density of dentin tubules and a greater tubule diameter which makes it appear “porous”(Aïem et al., 2020).These differences must be considered during removal of caries as primary teeth possess a higher risk of pulpal exposure (Aïem et al., 2020).

Treatment in the Primary Dentition

Indirect pulp Treatment(IPT):

This clinical approach in primary teeth aim to completely remove the carious lesion from the peripheral walls of the cavity, leaving soft dentin at the pulpal surface undisturbed (Franzon et al., 2007).This layer is then lined with a biocompatible material such as calcium hydroxide to allow the deep pulpal layer of dentin to remineralize with protecting the pulp from exposure (Aïem et al., 2020).The rationale behind this conservative technique is the increased capacity of healing in primary teeth due to increased vascularity of the pulp (Coll et al., 2008). Moreover, ensuring a proper restorative seal depends on the complete removal of all carious dentin from the lateral surfaces of the cavity, which is considered as an absolute requirement for the success of this approach (Aïem et al., 2020). Other factors affecting the success of IPT is the initial diagnosis of the pulpal condition, where spontaneous pain and pain at night can indicate irreversible pulpitis(AAE, 2009), which is a contraindication for this approach (Aïem et al., 2020), other contraindications are radiographical signs of periapical infection, draining fistula and soft tissue swellings (Aïem et al., 2020).

In DCL with vital pulps IPT and pulpotomy can be treatment of choice, however, IPT treatment is more cost-effective, simple and more acceptable to the child (AAPD, 2017).

Other reports suggest that IPT is more successful than pulpotomy with 80-90% success rates in treating DCL with IPT (Seale, 2010; Franzon et al., 2007; Al-zayer et al., 2003).

Various cavity liners have been used in IPT, these include calcium hydroxide, mineral trioxide aggregate(MTA) and Resin modified glass ionomer(RMGI) which are all considered bio-compatible to be placed close to the pulp (Modena et al., 2009). Calcium hydroxide is the most commonly used material in deep carious lesions, this is due to its long-term clinical success and its ability to stimulate reparative dentin formation due to its increased alkalinity (Modena et al., 2009).

Studies compared Calcium hydroxide with MTA and calcium hydroxide with resin adhesive system as a cavity liner in IPT, they found no statistically significant difference in the success of the indirect pulp treatment when the cavity seal was intact (Casagrande et al., 2010; Falster et al., 2002). Therefore, the type of liner used in IPT doesn’t affect the success of the procedure and the American academy of pediatric dentistry (AAPD) recommends that the clinician choose the material based on their individual preferences (AAPD, 2017).

Stepwise excavation

This technique involves re-entering the cavity after initial excavation, first the carious dentin is removed on the peripheral parts of the cavity and the soft carious dentin over the pulp will be left (Schwendicke et al., 2013).A cavity liner will be placed over the remaining soft dentin like calcium hydroxide and then the cavity is filled by a provisional restoration (Maltz et al., 2012). The provisional restoration must be durable enough for few months to prevent disruption of the seal and progression of caries (Schwendicke et al., 2013).Upon re-entering the soft dentin will be now remineralized and the operator will be able to re-assess the dentin texture and hardness if further excavation is necessary (Ricketts et al., 2013). After re-evaluation or further excavation, a cavity liner is placed, and the tooth is filled with a permanent filling material like composite or Stainless-steel crown (Ricketts et al., 2013)

The rationale behind this approach is by skipping the caries removal close to the pulp in the first step, this will allow the dentin to remineralize and for tertiary dentin to form, consequently, allowing the excavation and re-evaluation in the second visit with a lower risk of pulp exposure (Aïem et al., 2020). In spite of this, in the literature stepwise technique was shown to have increased chances of accidental pulp exposure than single entry IPT, Moreover, utilizing stepwise technique can add additional cost and discomfort to the child (Maltz et al., 2012).

failure of this technique was reported as a result of lost or impaired provisional restoration (Maltz et al., 2012). The literature is still inconclusive regarding the need to re-enter the cavity for additional excavation.

Some studies suggest the use of SDF (Silver Diamine Fluoride) in stepwise excavation (Crystal & Niederman, 2016). The silver acts as bactericidal while fluoride gets deposited on the tooth surface (Zaho et al., 2018). SDF 38% reported caries lesion arrest rates upwards of 70% (AAPD recommendations, 2018). The main disadvantage of SDF is the permanent discoloration of the enamel and dentin of the lesion (Crystal & Niederman, 2016). However, a material like Riva Star, that contains potassuim nitrate was shown to reduce black discoloration. (Crystal & Niederman, 2016). This is done when potassium iodide is in contact with SDF, excess silver ions causing black stains from SDF are removed by forming a silver iodide precipitate (Crystal & Niederman, 2016).

Treatment in the Permanent Dentition

Indirect pulp capping(IPC):

This treatment modality involves the non-selective removal of soft necrotic dentin in the superficial layer of the lesion along with selective excavation around pulpal dentin, intentionally leaving the deepest layer of dentin over the pulp to reduce the risk of pulp exposure (Gruythuysen et al., 2010).

Placement of liner material calcium hydroxide involves only the pulpal dentin avoiding the peripheral surfaces of the cavity as the dissolution of calcium hydroxide can lead to gap formation and seepage into the cavity (Carde & François,1997). IPC can be performed in two ways either in one visit like IPT with no re-entry or two-visit stepwise excavation after few months (Hilton, 2009). Upon re-entry demineralized dentin will be now remineralized and non-selective removal to hard dentin is preformed, this is evaluated according to gentle probing (Hilton, 2009).

In stepwise excavation the extent of caries removal should only be enough to fit a provisional restoration (Alsadat et al., 2018). Using a good quality provisional restoration such as ketac universal or IRM is important to the success of stepwise technique (Alsadat et al., 2018). A study showed that if patients fail to show up at the second visit, using zinc oxide eugenol cement caused a significant chance of failure of the treatment (Maltz et al., 2012). However, when comparing stepwise technique between the primary and permanent dentition it was found that there is more predictable outcome of treatment in permanent teeth with a success rate of 90% (Fagundes et al., 2009). 

The success criteria is evaluated by follow-up based on clinical and radiographic signs, clinically these include an intact coronal seal,  lack of symptoms of spontaneous pain and absence of a sinus tract (Alsadat et al., 2018). Additionally, radiographically the tooth should exhibit no signs of periapical changes nor an evidence of Internal or external root resorption (Aïem et al., 2020).

Final Restoration

The main success criteria for any treatment option is having a proper restoration with adequate marginal seal (Aïem et al., 2020). This is maintained by the complete removal of carious dentin at the margins of the cavity. The choice of materials for restoring cavities should be guided by the location and extent of the lesion (AAPD, 2017). Adhesive restoration such as Resin modified glass ionomer (RMGI) and compomer (COM) restorations showed similar longevity and a good marginal seal in moderate cavities. However, a badly destructive tooth can be restored by an extra-coronal filling such as a stainless-steel crown which is considered the most durable in this situation (Guelmann et al., 2005).

 

Conclusion

In the deep carious lesions strong evidence suggests the use of selective caries removal over the non-selective approach in both dentitions. Furthermore, in the permanent teeth, stepwise removal is suggested to be more liable than in primary teeth. Single step IPT in primary teeth was recommended due to the drawbacks of re-entry, such as loss of seal between appointments. However, the literature concludes that the failure of treating deep carious lesions is not related to the technique of the procedure but rather to the incorrect diagnosis of the pulp condition and compromised coronal seal. Lastly, more long‐term clinical trials are needed to determine which technique is more successful.

Reference

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