Access Cavities

The access cavity is the gateway to the root canal system. Its design determines how well the canals can be cleaned, shaped, and filled — and how much structural integrity the tooth retains afterwards.

Why access cavity design matters ?

The main objectives of obturation are:

• Provides straight-line or near-straight-line access to all canal orifices
• Enables effective irrigant delivery to the entire canal length
• Preserves pericervical dentin — the most biomechanically critical tooth structure
• A poorly designed cavity compromises all subsequent steps

Access Cavity Design Options

Four approaches exist, each with distinct trade-offs:

1. Traditional Access Cavity (TradAC) — Preserves all sound dentin; needs CBCT and good magnification to execute safely
2. Conservative Access Cavity (ConsAC) — Best overall balance of structural preservation and procedural reliability [1, 11]
3. Ultraconservative („Ninja“) Cavity — Maximum tissue preservation but significantly impairs canal detection and irrigation efficacy [2, 3]
4. Caries-Driven Cavity — Orients the access through existing caries — no healthy dentin sacrificed [4]

Evidence Summary

• Conservative (not ultraconservative) access offers the best balance of structural preservation and procedural safety [1].
• Ultraconservative cavities can impair canal detection and chemomechanical debridement [3].
• CBCT-guided access reduces angulation error from ~15° (freehand) to ~6° [4].
• Pericervical dentin preservation is the single most important structural goal [4].

Key Instruments Used in Access Cavity Preparation

Gates-Glidden Drills: PD Dental Gates-Glidden Drills

Gates-Glidden (GG) drills are used for coronal canal flaring — widening the upper canal third to provide straight-line access and reduce stress on NiTi files.

• Flame-shaped head with a safety non-cutting tip — prevents lateral perforation
• Sizes #1–#6; used crown-down (large to small) for maximum efficiency
• Restrict sizes >3 in curved or narrow anatomy — strip perforation risk increases significantly [6]
• Swiss-quality stainless steel; standardized shank fits all rotary handpieces

Peeso Reamers: PD Dental Peeso Reamers

Peeso reamers have a longer, parallel cutting surface suited to post-space preparation and gutta-percha removal during retreatment.

• Non-cutting tip design prevents apical transport
• Silicone depth rings available for controlled drilling depth
• Match reamer size to canal diameter radiographically to minimize dentin removal [7]
• Post-space preparation with any rotary instrument can induce root dentin defects — always preserve ≥5 mm of apical gutta-percha [8]