Pulpotomy is a vital pulp therapy procedure used to preserve the vitality of primary and permanent teeth with carious or traumatic pulp exposures. Historically, calcium hydroxide (Ca(OH)₂) has been the most commonly used medicament for pulpotomy; however, Mineral Trioxide Aggregate (dental MTA) has emerged as a superior alternative in terms of biological compatibility, sealing ability, and long-term success rates. This article reviews the clinical, biological, and practical differences between MTA and calcium hydroxide in pulpotomy procedures.
Introduction
Pulpotomy involves the removal of the inflamed coronal pulp while preserving the health of the radicular pulp. The choice of pulpotomy medicament greatly influences the outcome. For decades, calcium hydroxide was the gold standard due to its antibacterial properties and ability to stimulate reparative dentin formation. However, limitations such as poor sealing ability, tunnel defects in dentin bridges, and long-term failure have prompted the search for better materials.
Mineral Trioxide Aggregate (MTA), introduced in the 1990s, has shown superior sealing properties, excellent biocompatibility, and the ability to induce high-quality dentin bridge formation, making it a preferred choice in recent years.
Material Properties
| Property | Calcium Hydroxide (Ca(OH)₂) | Mineral Trioxide Aggregate (MTA) |
|---|---|---|
| Biocompatibility | Moderate | Excellent |
| Antibacterial Activity | High pH (strong antibacterial) | High pH (similar antibacterial) |
| Sealing Ability | Poor | Excellent |
| Induction of Dentin Bridge | Yes, but porous (“tunnel defects”) | Yes, dense and well-mineralized |
| Setting Time | Immediate chemical set | 2–4 hours (traditional MTA), immediate with MTA Z |
| Solubility | Relatively high | Very low |
| Long-Term Success | Moderate | High |
Biological Mechanism
- Calcium Hydroxide: Creates an alkaline environment (pH ~12) that is toxic to bacteria and stimulates pulp cells to produce reparative dentin. However, it causes a superficial necrosis zone, and dentin bridges formed are often porous, allowing bacterial microleakage.
- MTA: Composed mainly of tricalcium silicate, dicalcium silicate, and bismuth oxide. When set, it releases calcium ions and maintains an alkaline pH. It induces cementogenesis and dentinogenesis with minimal inflammation, producing a dense and continuous dentin bridge without tunnel defects.
Clinical Performance
Success Rates in Vital Pulp Therapy:
- Primary Teeth:
- Ca(OH)₂: 70–80% success over 12 months.
- MTA: 90–100% success over 12 months.
- Permanent Teeth:
- Ca(OH)₂: Higher failure rate in immature teeth due to microleakage and bridge defects.
- MTA: Better long-term sealing, reduced risk of pulp necrosis.
Advantages and Disadvantages
Calcium Hydroxide Advantages
- Inexpensive and widely available.
- Long clinical history and familiarity.
- Simple handling.
Calcium Hydroxide Disadvantages
- Poor sealing ability → higher risk of bacterial leakage.
- Tunnel defects in dentin bridges.
- Higher long-term failure rate.
- Solubility in oral fluids.
MTA Advantages
- Excellent sealing ability.
- High biocompatibility and bioactivity.
- Dense dentin bridge formation without tunnel defects.
- Reduced inflammation and pulp necrosis.
- Superior long-term clinical success.
MTA Disadvantages
- Higher cost.
- Longer setting time (except with light-curable or fast-set variants like dental MTA Z).
- Handling can be technique-sensitive (except with premixed MTA like MTA Z and EndoCem MTA)
Conclusion
While calcium hydroxide remains a viable pulpotomy agent due to its low cost and proven antibacterial action, MTA demonstrates significantly higher success rates, superior sealing ability, and better dentin bridge quality. For clinicians seeking predictable, long-term outcomes in pulpotomy—especially in immature permanent teeth—MTA is the recommended material despite its higher cost. The introduction of modified MTA formulations, such as dental MTA Z by Brexham, further enhances its clinical utility by enabling same-visit restorations and eliminating setting time limitations.
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