Conservative Caries Management to Preserve Tooth Structure

Restorative dentistry is predominantly centered on the management of caries affecting the remaining dentition. In recent years, restorative dentists have become increasingly conservative in their treatment of caries lesions of the enamel and dentin, whether they are incipient or more developed. The point at which caries lesions are identified determines the treatment indicated to arrest the demineralization process and restore the tooth to function. Accordingly, identification at the earliest stages of demineralization allows for more conservative intervention. The amount of natural tooth structure remaining has been correlated with tooth longevity. Therefore, the more enamel and dentin that can be preserved during treatment, the greater the longevity of the tooth.

When the posterior teeth are loaded during mastication, the cusps flex microscopically away from each other. If the tooth structure is compromised by caries in the pits and fissures of the occlusal surface, flexure increases under loading. That weakens the tooth and may lead to cuspal fracture, further compromising it. Placement of a restoration (eg, amalgam, composite, inlay) can also compromise a tooth's ability to resist cuspal flexure. Furthermore, as the teeth flex during mastication, stresses are concentrated in the cervical region, so preservation of this area is critical to long-term tooth survival as well. Given all of these factors, the preservation of coronal tooth structure is essential to maintaining long-term function and should be the goal of restorative treatment.

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Identifying Incipient Lesions

Early restorative intervention is indicated when changes to a tooth's surface are noted before deeper cavitation into the tooth structure has occurred. Cavitation is defined as microstructural damage to the enamel that exposes the underlying dentin to oral bacteria. This results in subsequent breakdown via acid attack and ultimately leads to caries.

Early caries may not be identifiable radiographically, and in the case of stained pits and fissures, it may not be identifiable with an explorer at its earliest stages. When an explorer is used to diagnose pit and fissure discoloration, light force should be applied with the tip because heavier force may increase the potential for cavitating the area.^1-4 The key to using an explorer to identify incipient caries in the pits and fissures is that the tip needs to be sharp. If the tip of the explorer is dull due to wear, it may not be able to contact the deepest parts of the pits and fissures and provide a tactile feel for the dentist or hygienist.

Due to the anatomy of pits and fissures, once caries that initiates in those areas gets past the enamel surface, it balloons, especially as dentin is contacted. Initial surface changes will appear as color changes to the enamel, which indicate the initiation of demineralization. When that initial breakdown reaches the underlying dentin, an incipient lesion is present, and restorative treatment is indicated. Because approximately 90% of the caries affecting permanent teeth and 44% of the caries affecting primary teeth occurs in the pits and fissures of the posterior teeth, early detection and treatment of incipient lesions in these areas is an important factor in preserving teeth.^5-7 Early intervention can also be an important factor in cervical root exposure of the dentin related to recession. This aids in both preventing the future breakdown of tooth structure and reducing tooth sensitivity.

Conservatively Treating Incipient Lesions in Pits and Fissures

The width and depth of occlusal pits and fissures in healthy, noncarious teeth varies from patient to patient. Shallow pits and fissures are easier for patients to maintain through home care. Patients with deep pits and fissures are more prone to developing incipient lesions because toothbrush bristles are often wider than the pits and fissures and unable to reach the bottom, which hampers home care and permits the initiation of caries.

Applying Sealants

The use of sealants has greatly improved caries prevention in vulnerable pits and fissures.^8-10 These are routinely recommended in children, but adults can also benefit from this conservative approach when incipient lesions are identified in the pits and fissures. These may initially present as dark stained areas (Figure 1 through Figure 4). Depending on the anatomy of the pits and fissures, in the absence of staining or an explorer stick in those areas, sealing the occlusal surface can be a good preventive measure to avoid the development of caries. In those cases, the preparation for the sealant may vary from acid etching the enamel to microetching with an air abrasion unit or an Er:YAG/Nd:YAG laser to improve bondability. These options will be operator dependent related to what is available in the practice. In children, traditional acid etching may be challenging due to the taste of the etching gel. The use of air abrasion or laser etching may make patient management easier in that patient population. Although the powder used in air abrasion cannot be confined to the surface of the tooth being treated, it has a neutral taste and may be less objectionable to younger patients. The benefit of using an Er:YAG/Nd:YAG laser is not only in eliminating issues with the taste and application time of etching gel and the disbursement of air-abrasion powder but also in reducing the time between the initiation of sealant treatment and placement of the resin on the tooth.

Minimal Preparation Restorations

Deeper pits and fissures that are heavily stained or those with definitive caries may require minimal preparation to access and remove the carious material prior to restoring those areas with an adhesive restorative material such as a flowable resin. The most minimally invasive way to accomplish this is through the use of high-speed, friction-fit carbide burs with a very narrow width and a tapered shape designed to conservatively access pits and fissures. Such pit and fissure treatment burs permit access to the affected areas while conserving adjacent tooth structure that would be removed with a traditional carbide bur (Figure 5). When discolored pits or fissures are identified as incipient lesions, either with an explorer or a caries detection device (Figure 6), a carbide pit and fissure treatment bur (Fissurotomy^®, SS White) can be used to prepare the affected spots  while preserving the healthy tooth structure (Figure 7). Then, following preparation, a flowable resin is bonded rather than a traditional sealant resin to create conservative restorations (Figure 8). Flowable resins are filled; therefore, they provide better wear resistance and improve the survival potential of these restorations.

Conservatively Treating Incipient Lesions Associated With Root Exposure

Gingival recession frequently leads to mechanical or chemical breakdown of exposed root surfaces. Typically, this is related to the patients' oral habits, diet, and other factors. We have all encountered patients with root exposure that demonstrates no structural changes and is stable for long periods of time. However, some patients develop root sensitivity and varying degrees of dentin exposure. Patients for whom structural breakdown of the root surface has initiated require conservative treatment to arrest further breakdown and eliminate any associated sensitivity.

Conservative treatment of these initial breakdowns in root areas aids in the preservation of tooth structure, is atraumatic, and can frequently be performed without the use of a local anesthetic with minimal tooth preparation.^11,12 Because the teeth flex in a buccal direction (maxillary teeth) or lingual direction (mandibular teeth) under occlusion, and stresses are concentrated in the cervical region, when restoring cervical root caries or abfractions, the creation of retention in the gingival and superior aspects of the preparation is recommended.¹³ This will prevent the restoration from popping out or the restorative margin from opening, which may lead to recurrent decay. A fine carbide pit and fissure treatment bur can be utilized to create that retention in a very conservative manner (Figure 9).

As the aging population is living longer, we are seeing a growing incidence of root exposure with subsequent dentin breakdown.^14,15 This becomes increasingly problematic in elderly patients with declining health issues and/or mental changes, such as dementia, that limit their ability to maintain their oral hygiene. The material selected for the treatment of these root areas should be either silver diamine fluoride, a glass ionomer (conventional or resin-modified), or a resin-based material (adhesive composite). Root surfaces are easily contaminated with saliva during treatment, which causes retention issues with bonded composites; therefore, a glass ionomer is more predictable to use. An additional benefit of using a glass ionomer is the fluoride release over time, which aids in the prevention of secondary decay.¹⁶

Conservatively Treating Advanced Lesions

Following removal of affected enamel and access to the carious dentin below, the majority of the carious dentin is removed with traditional diamond or carbide burs, which may leave affected dentin at the base of the preparation. In deep occlusal preparations, selectively removing carious dentin with a carbide or diamond bur while avoiding accidental pulpal exposure can be challenging (Figure 10). It is very difficult, if not impossible, to use tactile feel to remove carious dentin without removing unaffected healthy dentin. One way to prevent the removal of healthy dentin during preparation is by utilizing a slow-speed polymer bur that is harder than carious dentin but softer than unaffected dentin.¹¹ Because the polymer is softer than unaffected dentin, the bur will quickly wear when in contact with it, preventing inadvertent removal of that tooth structure and lessening the risk of accidental pulpal exposure. In cases involving deep cervical caries (Figure 11), a polymer bur (Smartbur II, SS White) in a slow-speed handpiece can be used to remove only the carious dentin (Figure 12), preserving all of the healthy dentin to maximize the tooth's ability to resist forces in this area (Figure 13).

Discussion

No restorative material currently in use can replicate the properties of sound enamel and dentin. The preservation of natural tooth structure has been correlated with long-term survival of the dentition and should be the goal of restorative treatment. The identification of breakdown of tooth structure at its earliest stages offers the best opportunity to preserve critical enamel and dentin. Demineralization of the enamel is the first sign of breakdown of tooth structure. Diet modification should be considered to decrease the consumption of foods and beverages that may increase the potential for demineralization and caries development. When the area of structural breakdown has reached the underlying dentin, conservative preparation with the most appropriate instruments allows access to those areas while preserving the surrounding unaffected dentin and enamel and reducing the chance of pulpal exposure.

About the Author

Gregori M. Kurtzman, DDS
Master
Academy of General
Dentistry
Diplomate
International Congress of Oral Implantologists
Private Practice
Silver Spring, Maryland

Figures and Images

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Fig. 1

Examples of early incipient caries of the pits and fissures of posterior teeth.

Fig. 2

Examples of early incipient caries of the pits and fissures of posterior teeth.

Fig. 3

Examples of early incipient caries of the pits and fissures of posterior teeth.

Fig. 4

Examples of early incipient caries of the pits and fissures of posterior teeth.

Fig. 5

Narrow, tapered carbide pit and fissure treatment burs enable preparation of the pits and fissures without the sacrifice of adjacent tooth structure that would occur with traditional burs.

Fig. 6

Pretreatment view of incipient caries lesions that were identified in the stained pits of these deciduous molars.

Fig. 7

A carbide pit and fissure treatment bur was used to conservatively prepare the pits.

Fig. 8

Posttreatment view of the conservative bonded composite restorations after finishing.

Fig. 9

A carbide pit and fissure treatment bur being utilized to create retention in the preparation for cervical caries treatment to reduce the potential of restoration pop-out during function.

Fig. 10

View of deep caries on the pulpal floor following initial tooth preparation.

Fig. 11

Pretreatment view of advanced cervical caries requiring restorative treatment.

Fig. 12

Following access to the carious dentin, a polymer bur was used to selectively remove the affected dentin while preserving the unaffected dentin.

Fig .13

View of the completed conservative preparation, which maximized the remaining healthy dentin to improve the tooth’s ability to resist the forces of loading that occur in this region.