Host: Dr. Melissa Seibert

Guest: Dr. Matt Chesler, Board-Trained Endodontist & Resident Faculty at Spear Education

Episode Summary

In this episode of Dental Digest, host Dr. Melissa Seibert sits down with endodontist Dr. Matt Chesler to break down the most intimidating aspects of molar endodontics . From overcoming access anxiety in deeply calcified teeth to navigating complex MB2 anatomy and proper hand-file selection, Dr. Chesler shares practical, evidence-based strategies to improve clinical confidence and prevent misadventures .

Guest Bio

Dr. Matt Chesler is a board-trained endodontist with over 20 years in the specialty and serves as resident faculty at Spear Education . He earned his DDS from the University of Southern California (USC), completed his endodontics residency at the Naval Postgraduate Dental School in Bethesda, and holds a Master of Science from George Washington University . He has been teaching clinical endodontics to dentists for over a decade .

Key Takeaways & Clinical Pearls

1. Molar Access vs. Anterior/Premolar Access

Greater Forgiveness: Molars offer significantly more space and room for minor access errors compared to anterior teeth or premolars, where the margins for error are much tighter .
Magnification & Illumination: High magnification and proper illumination are mandatory for identifying heavily calcified canals .

2. Access Strategy for Calcified Canals

Trajectory: Canals enter the pulp chamber at an angle rather than straight vertically .
Search Laterally First: Before taking down the pulpal floor, expand the access preparation laterally . Look for color changes and the historical outline of the pulp chamber .
Orifice Location: Orifices are typically located at the floor-wall junction .
Ultrasonics Over High-Speeds: Put away high-speed handpieces early to avoid damage . Use end-cutting ultrasonic tips (such as the Buck II tip) to drop the pulpal floor safely .

3. Critical Depth Benchmarks

Research Data (Dr. Alan Deutsch Studies):
- Average distance from occlusal surface to chamber roof: 6.25 mm .
- Average pulp chamber height: 1.5 mm to 2 mm .
Safety Rule: You generally have roughly 6.5 mm of safe drilling depth from the occlusal surface before reaching the chamber .
Radiographic Checkpoint: If you reach 6.5 mm to 7 mm in depth and have not entered the chamber, stop and take a radiograph to verify alignment and prevent perforation .

4. Workflow & Tactile Training

Initial Access: Start with a small bur (e.g., #330 or #1931) to identify the safe zone while preserving tooth structure .
Unroofing: Once inside the chamber, switch exclusively to non-end-cutting burs (e.g., Pulp Shaper or Endo-Z bur) to unroof without damaging the floor .
Tactile Practice: Practice access preps on extracted teeth with your eyes closed to develop a refined tactile feel for dropping into the chamber and running burs along walls .

5. Radiographs & CBCT

3D vs. 2D Imaging: CBCT serves as an "open book test" . It helps determine whether a canal is truly occluded versus calcified, eliminating unnecessary structure removal .
Follow Natural Pathways: Never try to create a new canal; always follow natural anatomy .

6. MB2 Anatomy & Canals

Prevalence: Expect to locate an MB2 canal in approximately 75% of maxillary molars .
Type 2 vs. Type 3 Systems:
- Type 2 System: Two separate orifices join into a single endpoint (V, Y, or lowercase h shape) .
- Type 3 System: Two completely independent canals from orifice to apex ("11" shape) .
Instrumentation Tip: On Type 2 systems, your file may hit a wall where MB2 joins MB1 . When backfilling MB1 with warm gutta-percha, you will often see MB2 fill simultaneously via the confluence .

7. Hand File Selection & Pre-Curving

Start Small: Use a #6 hand file rather than a #10 file to negotiate tight or calcified canals . A #6 file often glides through where a #10 file buckles .
C-Files vs. K-Files:
- C-Files: Feature a stiffer shaft and active tip, making them ideal for finding and opening orifice tops .
- K-Files: Switch to K-files once the orifice is located to prevent ledging .
Single-Use Files: Discard distorted hand files immediately to avoid file separation .
Understanding Calcification: Canals calcify top-down, not bottom-up . Hitting a hard stop mid-canal (e.g., at 15 mm in a 20 mm canal) usually indicates a curve rather than calcification .
Pre-Curving Technique: Place a smooth 30° to 55° bend on the last few millimeters of the file (acting like a mini explorer) using your fingers or an explorer handle to bypass curves . Avoid sharp kinks .

Demystifying Molar Access & Calcified Canals with Dr. Matt Chesler

Dental Digest Podcast with Dr. Melissa Seibert

Demystifying Molar Access & Calcified Canals with Dr. Matt Chesler