Pulp capping is a technique used in dental restorations to protect the dental pulp, after it has been exposed, or nearly exposed during a cavity preparation, from a traumatic injury, or by a deep cavity that reaches the center of the tooth, causing the pulp to die. Exposure of the pulp causes pulpitis (an inflammation which can become irreversible, leading to pain and pulp necrosis, and necessitating either root canal treatment or extraction). The ultimate goal of pulp capping or stepwise caries removal is to protect a healthy (or reversibly inflammed) dental pulp, and avoid the need for root canal therapy. When dental caries is removed from a tooth, all or most of the infected and softened enamel and dentin are removed. This can lead to the pulp of the tooth either being exposed or nearly exposed. To prevent the pulp from deteriorating when a dental restoration gets near the pulp, the dentist will place a small amount of a sedative dressing, such as calcium hydroxide or mineral trioxide aggregate (MTA). These materials protect the pulp from noxious agents (heat, cold, bacteria) and stimulate the cell-rich zone of the pulp to lay down a bridge of reparative dentin. Dentin formation usually starts within 30 days of the pulp capping (there can be a delay in onset of dentin formation if the odontoblasts of the pulp are injured during cavity removal) and is largely completed by 130 days. As of 2021, recent improvements in dressing materials have significantly increased the success rates of pulp capping teeth with cavities. Two different types of pulp cap are distinguished. In direct pulp capping, the protective dressing is placed directly over an exposed pulp; and in indirect pulp capping, a thin layer of softened dentin, that if removed would expose the pulp, is left in place and the protective dressing is placed on top. A direct pulp cap is a one-stage procedure, whereas a stepwise caries removal is a two-stage procedure over about six months.
Direct
This technique is used when a pulpal exposure or near-exposure occurs, either due to caries extending to the pulp chamber, or accidentally, during caries removal. It is only feasible if the exposure is made through uninfected dentin, and any pulpitis is reversible (that is, there is no recent history of spontaneous pain, indicating irreversible pulpitis) and a bacteria-tight seal can be applied. Once the exposure is made, the tooth is isolated from saliva to prevent contamination by use of a dental dam, if it was not already in place. The tooth is then washed and dried, and the protective material placed, followed finally by a dental restoration which gives a bacteria-tight seal to prevent infection. Since pulp capping is not always successful in maintaining the vitality of the pulp, the dentist will usually keep the status of the tooth under review for about a year after the procedure. Success rates (the chance that the tooth will be preserved) have risen with newer protective materials.
Indications for direct pulp capping Indications for direct pulp capping include:
Immature/mature permanent teeth with simple restoration needs Recent trauma less than 24 hours (less according to tichy) exposure of pulp / mechanical trauma exposure (during restorative procedure) Minimal or no bleeding at exposure site Normal sensibility test Not tender to percussion No periradicular pathology Young patient
Contraindications for direct pulp capping Contraindications for direct pulp capping include:
Systemic disease involvement Primary teeth Inflammatory signs and symptoms Pre-operative tooth sensitivity Large pulpal exposure Uncontrollable bleeding from the pulp Non-restorable tooth Elderly patient
Indirect In 1938, Bodecker introduced the stepwise caries excavation (SWE) technique for treatment of teeth with deep caries for preservation of pulp vitality. This technique is used when most of the decay has been removed from a deep cavity, but some softened dentin and decay remains over the pulp chamber that if removed would expose the pulp and trigger irreversible pulpitis. Instead, the dentist intentionally leaves the softened dentin or decay in place, and uses a layer of protective temporary material which promotes remineralization of the softened dentin over the pulp and the laying down of new layers of tertiary dentin in the pulp chamber. The color of the carious lesion changes from light brown to dark brown, the consistency goes from soft and wet to hard and dry so that Streptococcus mutans and Lactobacilli have been significantly reduced to a limited number or even zero viable organisms and the radiographs show no change or even a decrease in the radiolucent zone. A temporary filling is used to keep the material in place, and about six months later, the cavity is re-opened and hopefully there is now enough sound dentin over the pulp (a "dentin bridge") that any residual softened dentin can be removed and a permanent filling can be placed. This method is also called "stepwise caries removal." The difficulty with this technique is estimating how rapid the carious process has been, how much tertiary dentin has been formed and knowing exactly when to stop excavating to avoid pulp exposure.
Materials The following materials have been studied as potential materials for direct pulp capping. However, calcium hydroxide and mineral trioxide aggregate (MTA) are the preferred material of choice in clinical practice due to their favourable outcome.
Zinc oxide eugenol Zinc oxide eugenol (ZOE) is a commonly used material in dentistry. The use of ZOE as a pulp capping material remains controversial. This is due to eugenol, being cytotoxic to the pulp, being present in large quantities in this formulation. Also due to its nature of non-adhesive, it leads to poor coronal seal hence increasing micro-leakage. Studies have demonstrated unfavourable results for ZOE when compared to calcium hydroxide as a direct pulp-capping material as it causes pulpal necrosis.
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