Pulp treatment in primary teeth. Methods, materials, protocols

The treatment of pulp in primary teeth is of paramount importance, as these teeth play a vital role in the development of a child's occlusion. They contribute significantly to space management within the growing dental arches, the temporomandibular joint (TMJ), and the eruption of permanent successor teeth. Therefore, the premature loss of deciduous teeth can lead to functional issues and malocclusions, making it essential for practitioners to preserve pulpally involved teeth until their natural exfoliation.

However, pulp treatment in children presents unique challenges. The extent of infection and vitality of pulp tissues can only be accurately assessed through histological examination, which is impossible in our practice. What is more, communication with young patients is frequently limited.

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Pulp treatment approaches for primary teeth are generally categorized into two main types:

1. Vital pulp therapy

• Indirect Pulp Treatment (IPT)
• Direct Pulp Capping (DPC)
• Pulpotomy

       2. Nonvital pulp therapy

• Pulpectomy
• Root filling

In the early stages of pulp inflammation, the clinician's treatment approach involves a comprehensive array of therapeutic interventions designed to effectively eliminate the inflammatory process, utilizing medications aligned with methods of vital pulp therapy. As the condition progresses, the extent of the inflammatory development – whether it results in partial or total pulp necrosis – necessitates a precise diagnosis of pulpitis. This diagnosis will inform the required intervention, such as pulpotomy or pulpectomy. Prior to this, it is essential to determine the appropriate method of pain relief, which may involve anesthesia (the vital method) or devitalization. In cases of devitalization, the success of treatment and the preservation of pulp function are closely linked to the condition of the remaining pulp.

Indirect Pulp Treatment (IPT)

Indirect Pulp Treatment (IPT) is a procedure that involves saving the thin soft dentin layer in deep cavitated lesions and covering it with a biocompatible material.

Administration of such material results in the formation of tertiary and peritubular (sclerotic) dentin, which results in greater distance between the remaining dentin and the pulp and lower dentin permeability.

The main objective:

• To maintain pulp vitality

Goals:

• Halt the carious process.
• Prevent the leakage of infection into the pulp.
• Stimulate the formation of tertiary dentin.
• Promote the remineralization of dentin.

Indications:

• Deep carious lesions without symptoms of pulp degeneration

Materials:

• Calcium hydroxide
• Glass ionomer
• Mineral trioxide aggregate (MTA)

Procedure for Indirect Pulp Treatment:

1. Administer pain control.
2. Ensure a sterile environment using a rubber dam.
3. Remove infected dentin until the firm resistance of sound dentin is felt. If all the carious dentin was removed except the portion that would expose the pulp, a second appointment and re-entry might be necessary.
4. Irrigate the cavity with sterile saline and dry with cotton pellets.
5. Cover the cavity floor with the chosen material.
6. Place a permanent restoration. If some carious dentin was left, place a temporary restoration and schedule the second appointment in 6-8 weeks.
7. If a second visit is required, re-enter the cavity to remove any remaining caries that have dried and flaked until reaching a reparative dentin bridge.
8. Place a permanent restoration.

Direct Pulp Capping (DPC)

Direct Pulp Capping (DPC) is performed in cases of a healthy pulp exposure during an operative procedure.

The main objective:

• To preserve pulp vitality or heal the pulp.

Goals:

• Stop the carious process.
• Prevent infection from reaching the pulp.
• Stimulate the formation of a tertiary dentin bridge.
• Promote remineralization of dentin.

Indications:

• Deep carious lesions without pulp degeneration symptoms.
• Pinpoint to 1 mm sized mechanical or carious exposure
• Reversible pulpitis

Limitations:

DPC is generally not recommended for deciduous teeth due to unpredictable and potentially unsatisfactory prognoses. Key reasons include:

• Primary teeth are naturally programmed for exfoliation, and any pulp intervention may trigger odontoclast differentiation, leading to premature root resorption.
• Increased blood supply, poor infection localization, and a rapid inflammatory response complicate treatment.

Materials:

• Calcium hydroxide (calcium hydroxide powder with distilled water, pulpdent, Dycal, Hydrex)
• Bioactive cements (Biodentin)
• Mineral trioxide aggregate (MTA)
• Glass ionomer and resin-modified glass ionomer cements
• Agents including corticosteroids and antibiotics
• Dentin bonding systems

Procedure for Direct Pulp Capping:

1. Administer pain control.
2. Maintain a sterile environment using a rubber dam.
3. Remove deep dentinal caries thoroughly to prevent pulp contamination.
4. After exposure, irrigate the cavity with sterile saline or distilled water.
5. Apply sterile cotton pellets for 1-5 minutes to control hemorrhage, avoiding blood clots between the exposure site and capping material as they can hinder healing.
6. Apply the chosen capping material with minimal pressure.
7. Place a temporary or final restoration.

Pulpotomy

Pulpotomy involves the removal of the coronal pulp while preserving the radicular pulp, thereby maintaining tooth vitality. The procedure is based on the rationale that after surgical amputation of the coronal pulp, the radicular pulp remains healthy and is capable of healing and normal functioning.

The main objective:

• To preserve the radicular pulp vitality and save the tooth

Goals:

• Eliminate infection and inflammation by removing the coronal pulp.
• Allow the tooth to exfoliate naturally within its physiological lifespan.

Indications:

• Deep carious lesions with pulp exposure and no signs of radicular pulpitis.
• Trauma.
• Controlled hemorrhage from the exposure site that is bright red.
• Only spontaneous pain present.
• Absence or only up to 1/3^rd root resorption

Materials:

• Formocresol
• Glutaraldehyde
• Calcium hydroxide (calcium hydroxide powder with distilled water, pulpdent, Dycal, Hydrex)
• Bioactive cements (Biodentin)
• Mineral trioxide aggregate (MTA)
• Zinc Oxide Eugenol (ZOE)

Procedure for Pulpotomy:

1. Administer pain control.
2. Ensure a sterile environment using a rubber dam.
3. Remove deep dentinal caries from peripheral to pulpal areas to access the coronal pulp, ensuring all necrotic and infected tissues are eliminated.
4. Amputate the coronal pulp cleanly at the level of the pulpar floor using sharp, high-speed rotary instruments, ensuring no residual tissue remains.
5. Achieve hemostasis within 5 minutes using sterile cotton pellets soaked in saline.
6. Gently rinse the amputation site with sterile saline or sodium hypochlorite (NaOCl).
7. If bleeding persists, consider pulpectomy or extraction.
8. Apply therapeutic material to the pulpotomy site.
9. Seal the tooth with a temporary or final restoration, ideally a full coverage restoration.

Pulpectomy

Pulpectomy entails the complete removal of both coronal and radicular pulp, followed by filling the root canals with a resorbable material.

The main objective:

• To eliminate infection and maintain space for successor teeth

Goals:

• Biomechanically cleanse and fill the root canals.
• Facilitate root resorption and allow the tooth to exfoliate naturally within its physiological lifespan.

Indications:

• Irreversible pulpitis or pulp necrosis with adequate periodontal and bony support (minimal root resorption).
• Uncontrolled hemorrhage from the exposure site that is dark red.

Filling Materials:

• Iodoform
• Zinc Oxide Eugenol (ZOE)
• Calcium hydroxide (calcium hydroxide powder with distilled water, pulpdent, Dycal, Hydrex)
• Walkoff paste (Parachlorophenol + camphor + menthol)
• Mineral trioxide aggregate (MTA)

Procedure for a single-visit Pulpectomy:

1. Administer pain control.
2. Ensure a sterile environment using a rubber dam. Remove caries and access the pulp chamber.
3. Remove the coronal pulp and locate each canal orifice, extirpate the radicular pulp tissue.
4. Use one of the methods (tactile, radiographs, apex locators) to estimate the preliminary working length.
5. Select and adjust endodontic files to stop 1-2 mm short of the radiographic apex, bending the instruments slightly according to canal curvature.
6. Mechanically clear organic debris using rotary instruments, Ni-Ti instrumentation, laser therapy, or ultrasonic instrumentation, avoiding perforations in the furcation and lateral walls.
7. Periodically irrigate the canals to disinfect and remove debris.
8. Dry the canals thoroughly.
9. Obturate the canals, starting with a thin mix of cement to coat the walls, then using a thicker mix to fill the canals, adding material until no further cement can be incorporated.
10. After complete filling with resorbable material, press with cotton pellets and take a periapical radiograph.
11. Ensure a leakage-free restoration, preferably a full crown.

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Procedure for a multiple-visit Pulpectomy:

First Appointment:

1. Administer pain control.
2. Ensure a sterile environment using a rubber dam. Remove caries and access the pulp chamber.
3. Remove all accessible pulp tissues.
4. Place a cotton pellet soaked in formocresol in the chamber and cover it with a temporary restoration.

Second Appointment (5-7 days later):

1. Remove the temporary restoration.
2. Repeat steps 3-11 from the single-visit pulpectomy protocol.

Medications and materials used for Pulp Treatment in Primary Teeth

Materials for pulp treatment serve various purposes, each exhibiting distinct mechanisms of action on the remaining pulpal tissue. Some, such as formocresol and glutaraldehyde, function as fixing agents, while others like ferric sulfate serve a hemostatic role. Antibacterial properties are attributed to sodium hypochlorite (NaOCl), and corticosteroids, often combined with antibiotics, are utilized for their anti-inflammatory and bacterial control effects. Additionally, zinc oxide and eugenol (ZOE) have historical significance due to eugenol's longstanding use as a desensitizer.

Regenerative materials focus on forming a calcium bridge and promoting the development of reparative dentin. Calcium hydroxide (Ca(OH)₂), the earliest example in this category, exhibited limited success due to its heightened alkalinity, which often incited inflammation and necrosis, ultimately leading to internal resorption. In contrast, newer regenerative bioactive calcium silicate cements, such as mineral trioxide aggregate (MTA) and Biodentin, have emerged as not only comparable to the traditional gold standard but preferable for various reasons.

Some materials and techniques have failed to gain traction due to suboptimal clinical performance compared to formocresol, or because they elicited adverse effects such as pulp inflammation, pain, and internal resorption. Nevertheless, certain materials continue to be utilized by clinicians despite their limitations, whether due to lower efficacy or undesirable side effects.

It is essential to consider these materials and techniques within their broader context. While advancements in technology have led to the development of new bioactive calcium silicate cements, current comparative studies have yet to provide sufficient high-quality evidence to endorse a singular gold standard material for pulpotomies in primary teeth.

Calcium hydroxide

Calcium hydroxide is a white, crystalline basic salt that dissociates into calcium ions and hydroxyl ions when dissolved in solution, exhibiting a high alkalinity with a pH of 11. When applied to pulpal tissues, calcium hydroxide promotes the formation of a dentin bridge. Initially, alkaline phosphatase, an essential enzyme in mineralization, is activated, and a necrotic zone develops adjacent to the material, and the alkaline environment fosters the differentiation of surrounding tissue into odontoblasts, which create a matrix. Over time, the necrotic area is resorbed and replaced by the dentin bridge.

Common formulations for direct pulp capping include calcium hydroxide powder mixed with distilled water, as well as proprietary products like Pulpdent, which contains 52.5% calcium hydroxide in a methyl cellulose solution, and Dycal and Hydrex, which combine calcium hydroxide with barium sulfate and titanium dioxide.

Dentin bonding systems

Dentin bonding systems are used for Indirect Pulp Treatment (IPT) and Direct Pulp Capping (DPC). The appeal of these systems lies in their ability to create a polygenic film that can be delicately layered over an exposure site without displacing the pulp tissue, extending onto the surrounding dentin where it permeates the tubules. This adhesive film, once cured by light, serves as an effective barrier, allowing a composite resin to be gently spread over the pulp and into the adjacent dentin.

MTA

Mineral trioxide aggregate (MTA) has been shown to effectively induce hard-tissue formation within pulpal tissues while promoting rapid cellular proliferation. Histological evaluations of pulpal tissue reveal that MTA facilitates the development of a thicker dentin bridge, accompanied by reduced inflammation, diminished hyperemia, and less pulpal necrosis when compared to calcium hydroxide. Notably, MTA appears to accelerate the formation of the dentin bridge more rapidly than calcium hydroxide. The tricalcium oxide present in MTA reacts with tissue fluids to generate calcium hydroxide, thereby promoting hard-tissue formation in a manner analogous to calcium hydroxide itself. Favorable pulp responses in primary teeth following direct pulp capping with MTA have been reported.

​​Biodentine

Biodentine is a bioactive cement that exhibits mechanical properties akin to those of natural dentin. Introduced as "the first universal, bioactive, and biocompatible material for the replacement of damaged dentin," Biodentine demonstrates excellent adhesion to dentin, ensuring a secure seal in the marginal zone of restorations. Its biocompatibility is noteworthy; it does not harm pulp cells in vitro or in vivo and has the capability to stimulate the formation of tertiary dentin. Hard tissue formation has been observed following both indirect and direct pulp capping procedures utilizing Biodentine. When in direct contact with pulp tissue, it promotes the formation of reparative dentin. Due to its enhanced properties, Biodentine presents a compelling alternative to calcium hydroxide-based materials, offering advantages in direct pulp capping and, when appropriately indicated, contributing to the long-term preservation of tooth vitality.

Biodentine is a two-component material comprising a powder and a liquid. The powder consists of tricalcium silicate, dicalcium silicate, calcium oxide, and calcium carbonate as fillers, with zirconium oxide included as a radiopaque agent. The liquid component contains calcium chloride as a catalyst and a water-reducing agent. The catalyst facilitates the material’s rapid hardening within 12 minutes, while the water-reducing agent minimizes the risk of crack formation, a common issue associated with cements containing high water content.

Furthermore, Biodentine addresses some of the tooth staining concerns associated with MTA following pulp capping and is effective in inducing mineralization and cellular differentiation. When compared to calcium hydroxide, Biodentine offers several advantages: it is mechanically stronger, less soluble, and provides superior sealing properties. Consequently, Biodentine effectively mitigates the three primary disadvantages of calcium hydroxide: material resorption, mechanical instability, and the resultant loss of restoration sealing.

Formocresol

Formocresol has undergone numerous modifications and adaptations in the techniques employed for formocresol pulpotomies over the years. It comprises 35% cresol, 15% glycerol, 19% formaldehyde, and 31% water. In contemporary practice, a diluted version of this formula is utilized, specifically a 1/5th concentration. The mechanism of action of formocresol is primarily attributed to its ability to prevent tissue autolysis through bonding with proteins. This bonding occurs with the peptide groups of side chain amino acids and is a reversible process that does not alter the fundamental structure of protein molecules.

Upon application, the pulp tissue initially transforms into a fibrous and acidophilic state. Within a timeframe of seven to fourteen days, three distinct zones become apparent: a broad eosinophilic zone indicative of fixation, a pale-staining zone characterized by atrophy and poor cellular definition, and a broad zone of inflammation that extends apically into the normal pulp tissue.

Glass ionomer cement (GIC)

Glass ionomer cement (GIC) is recognized as a caries-static material with the unique ability to both accumulate and release fluoride ions. Fluoride plays a crucial role in controlling demineralization processes and exhibits antimicrobial properties by inhibiting the enolase enzyme, which is essential for the phosphotransferase system that governs bacterial metabolism.

One of the remarkable features of glass ionomer cement is its capacity to "forgive" errors in cavity preparation, allowing for the complete removal of infected dentin while preserving demineralized dentin that retains the potential for remineralization at the base of the carious cavity. The fluoride release from GIC is a prolonged process, extending beyond one year. The diffusion of fluoride ions, along with other apatite-forming ions such as silicates and calcium ions, enhances the mineralization of dental tissues, reduces dentin permeability, facilitates the remineralization of initial carious lesions, and effectively halts or slows the progression of caries. The dental tissue surrounding and beneath glass ionomer cement becomes denser and hypermineralized as a result. Furthermore, GIC provides reliable sealing and protection for the pulp against bacterial invasion, exhibiting high biocompatibility when used in proximity to the pulp, although it is not intended for direct contact.

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