Current caries removal procedures
Introduction
If caries are left untreated, they will progress through the dentin and cause pulpal inflammation, then eventually pulpal infection and finally necrosis. However, if there is no irreversible damage and they are managed conservatively, pulpal healing can occur even in deep caries.
- Carious eviction: Definition
Carious removal is the second challenge after the establishment of the surgical field (dam) and it is the determining element of the restorative strategy.
- Carious removal techniques:
Several approaches can be used:
- Complete (non-selective) caries removal
- Partial eviction in one step: selective eviction.
- Partial eviction in two stages: Step wise
- Total eviction
Total or complete or non-selective eviction is the total eviction of carious tissue until healthy and hard dentin is obtained on all the walls of the cavity. Clinically, it is commonly accepted that the removal of demineralized dentin is complete when the probe emits a
“Dentin cry”, concomitant with a feeling of resistance of normal dentin. This technique is based on the idea that the success of the restoration can only be obtained if all the bacteria have been removed.
- Partial evictions
Partial eviction has two techniques: either the so-called “Stepwise” technique in two stages, or selective eviction in one stage.
This treatment is indicated in deep dentin lesions to avoid pulp exposure.
Avoiding pulp exposure helps to:
-Reduce the risk of bacterial infection, but since dentin is tubular, if the remaining dentin layer before breaking is less than 1 mm, it is as permeable as if the breaking had been done.
‐ Preserve the odontoblastic barrier.
‐Dentin can release growth factors and thus stimulate repair.
- Partial eviction in one stage: selective eviction
One-stage partial eviction is also called selective eviction. It is a method of eviction in which carious dentin from a deep lesion is removed from the periphery to the center of the lesion. The peripheral areas are cleaned until hard dentin is obtained. A partial eviction is then performed in the areas close to the pulp.
- Partial eviction in two stages: Step wise
The two-stage partial eviction or “Stepwise Technique” was created with the aim of reducing pulpal breakages during curettage. As with the one-stage technique, the lesion is carefully cleaned on the periphery and the practitioner leaves a base of demineralized dentine in contact with the pulp and places a restoration that will only be temporary. In a second stage, subject to pulp vitality, the temporary restoration is completely removed. If there is residual demineralized tissue, it is removed and then the definitive restoration is placed.
- Means of caries eviction in dentistry
Several instruments simplify operating techniques and make them reproducible.
- Chemical and mechanical aids for caries prevention
- Strawberries
Several types of burs can be used for caries removal and cavity preparation.
- Tungsten Carbide Burrs
sharp edges that can be straight, spiral-shaped and with or without the presence of cross-sections. used on blue ring contra-angles, treat both dentin and enamel.
Water spray when using it is essential for debris removal and temperature control. They can lead to over-preparation
Tungsten Carbide Burrs
- Ceramic strawberries
- Composed of zirconia ceramic alloyed with alumina oxide.
- Resistance to compression, wear
- Harder than classic strawberries.
- Low speed use,
- They allow selective caries elimination, and are therefore very useful for partial caries removal.
- Made of a polyamide polymer,
- The edges are straight.
- Prevent pulp damage because they become blunt on contact with healthy hard tissue.
- Used on low speed contra-angle, with or without water spray.
- They are for single use only.
CeraBur ceramic bur, Komet
- Polymer strawberries
Made of a polyamide polymer, the straight edges prevent pulp breakage because they become blunt on contact with healthy hard tissue. Used on a low-speed contra-angle, with or without water spray. They are for single use.
PolyBur, Komet milling cutter
Polymer burs appear to be the only truly self-limiting ones. Because they become blunt upon contact with hard tissues, they are unlikely to overprepare healthy tissues.
They therefore allow maximum tissue conservation and also limit the risk of pulp damage.
Eviction using this type of bur may take a little longer than with tungsten carbide burs.
- Chemomechanical gels
Carious eviction using chemomechanical gels is an excellent method for minimally invasive carious excavation.
Active agents may be based on sodium hypochlorite NaOCl (such as Caridex® or
Carisolv®) or enzyme-based (such as Papacarie® or Biosolv®, which is still experimental).
This eviction technique is slow, but less painful than complete eviction down to the hard dentin, with less risk of complications.
- Example of a chemo‐mechanical gel based on NaOCl‐: Carisolv®
The Carisolv® system consists of two gels:
A chlorinated gel (a specific gel based on sodium hydroxide, sodium chloride, carboxy methyl cellulose and amino acids such as glutamic acid, leucine, lysine, etc.).
And a 0.95% sodium hypochlorite gel capable of dissolving carious dentin.
It is used with the help of specific transport and excavation instrumentation.
The product should act for 30 seconds to further soften the infected dentin. The latter will be curetted using hand instruments specifically designed for Carisolv®.
This sequence is repeated as many times as necessary, i.e. until the gel is free of debris. However, a maximum tissue contact time of 10 minutes should not be exceeded for the entire procedure.
Action of Carisolv gel
- Example of chemo-mechanical gel based on enzymes: Papacarie®
Papacarie® is a papain-based gel. Although it contains small amounts of chloramine, the action of the gel depends on the papain. Papacarie has shown a shorter excavation time than Carisolv®.
Papacarie® should act for 30 seconds for active lesions and 40 to 60 seconds for stopped lesions.
After action, the cavity is curetted using a hand instrument. There is no need to rinse the product.
A new application of Papacarie® can be done immediately and until the infected dentin is completely removed.
- Lasers
Concerning the Er: AG laser, the emission is in the infrared at a wavelength of 2940 nm, in a pulsed mode. Its wavelength is strongly absorbed by water. Much more effective on tissues with a high water composition such as carious tissues. It allows selective eviction while sparing healthy tissues.
The Er:YAG laser is therefore a potential replacement for rotary instruments for the removal of carious lesions.
Er:YAG laser, and optical contra-angles (left) and laser beam transmission (right)
- Air abrasion
Air abrasion is a micro-invasive eviction technique.
Depending on the pressure and the type of particles used, the systems can have a prophylactic air-polishing action or a real abrasive role allowing caries removal.
Pneumatic abrasion involves projecting fine particles of sand under pressure to remove cavities.
Tissue removal is usually achieved by high-pressure projection of aluminum oxide particles. The action will be different depending on the target tissue, it will result in cutting of rigid materials, while an abrasion effect will be observed on more ductile substrates, such as carious tissues. As a result, carious dentin will be more difficult to remove.
The preparation is optimal with a pressure of 30-60 psi for 27 µm aluminum oxide particles and an Action Distance of 0.5 to 2 mm.
Air abrasion used for the removal of caries from the grooves with 27 micron particles.
1) Caries of the grooves on the second mandibular molar
2) Tip of the air abrasion device placed on the tooth
3) Carious removal with minimal preparation
4) Restoration (under microscope x16)
- Ultra-sono-abrasion and sono-abrasion
All these ultrasonic and sonic processes have an effectiveness dependent on the hardness of the residual tissues and remain ineffective on softened dentin.
The inserts have three mechanical actions :
- A so-called percussion action, allowing the removal of unsupported enamel. This removal is selective. In fact, only fragile tissues will be removed while preserving the resistant walls.
- A sweeping action, allowing the elimination of decayed tissues using a back and forth movement along the walls.
- An abrasive action to complete the carious removal, to achieve the finishing touches by making the walls more homogeneous, thus facilitating bonding.
The harder the tissue, the more effective the insert will be. Ultrasound therefore has little effect on soft tissues, and will have the disadvantage of limited removal of softened carious dentine.
On the other hand, they have the advantage of having few iatrogenic effects on soft tissues such as gingival tissues, thus avoiding lesions of the periodontium and its bleeding. This will facilitate bonding, sealing and therefore the quality of the restorations.
Patients report reduced intraoperative noise and pain, which supports their use
Using a tip (Kavo) for micro-preparation of the approximate cavity.
a) Access through the enamel for a diamond bur through the marginal ridge; FenderPrep, Codimed® protection system in place;
(b) Assessment of the lesion after limited marginal ridge removal;
(c) Assessment of the lesion after limited marginal ridge removal.;
(c) Removal of carious tissue and rough shaping using the smooth surface of tip 33 resting on the marginal ridge.the smooth surface of tip 33 resting on the adjacent tooth and the convex coated surface working on the outer side of the marginal ridge;
d) Clinical outcome: note the removal of undermined enamel and the concave preparation of the approximate margin.
SonicSys micro® (Kavo) hemispherical tip 33 micro for preparations) Cervical edge finish, smooth side facing, Codimed® protection system
;b) Clinical result: note the regularity of the cervical edge margin of the enamel.
Conclusion
The removal of carious tissues is a major issue in the modern approach to restorative dentistry . It must allow not only the preservation of pulp vitality, the preservation of hard tissues, but also the realization of restorations that are part of the long term. The appropriate therapeutic approach follows a simple model that is easily achievable in our daily practice.
Current caries removal procedures
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