For dental students, residents, and referring doctors
The protocols Dr. Kung uses in daily practice, with the literature that supports them. Most of this is not patient-facing — it is here so dental students, residents, and referring colleagues can see what evidence drives the technique, and so the rationale is auditable rather than asserted.
The four steps below are the modern microsurgical sequence as defined by Kim & Kratchman (2006) and confirmed in outcome by Setzer et al. (2010, 2012). Where they differ from traditional root-end surgery — smaller osteotomy, perpendicular resection, ultrasonic retro-prep, bioceramic fill — is exactly where the 35-percentage-point success advantage comes from.
A 3–5 mm osteotomy is sufficient when guided by CBCT and the surgical microscope. The historic 8–10 mm osteotomy of traditional surgery is unnecessary and removes healthy bone that does not need to be removed.
A 3 mm apical resection removes ~98% of apical ramifications and lateral canals. The bevel is kept as close to perpendicular as access allows, exposing the canal cross-section for inspection rather than smearing dentinal tubules at an acute angle.
A 3 mm class-I retro-preparation is cut along the long axis of the canal with diamond-coated ultrasonic tips. This follows the natural anatomy — including isthmuses — that a round bur cannot.
Bioceramic putty (BC RRM / EndoSequence) or MTA is placed under microscope visualization. Both are bioactive, hydrophilic, and dimensionally stable in the presence of moisture — the conditions that previously made amalgam, IRM, and SuperEBA unreliable at the apex.
"More magnification is always better" is a misconception. Each stage of the case has a magnification range that maximizes useful information without losing field of view. The Zeiss OPMI surgical microscope steps cleanly through these ranges; loupes can approximate the low and mid ranges but cannot reach the high range where molar isthmus identification happens.
| Range | Used for | Notes |
|---|---|---|
| Low (4–8×) | Orientation, flap design, suturing | Wide field of view; used at the start and end of every case. |
| Mid (10–12×) | Osteotomy, root-end resection, hemostasis check | Working magnification for most of the procedure. |
| High (16–25×) | Isthmus identification, micro-crack detection, retro-prep inspection | Decisive for molar outcomes — see Setzer 2012, Part 2. |
The root-end material has changed more in the last 25 years than the rest of the surgical sequence combined. Each generation solved a specific failure mode of the previous one: leakage (amalgam → IRM/SuperEBA), then biocompatibility and seal in moisture (legacy → MTA), then handling and set time (MTA → bioceramics).
Amalgam (1960s–1990s)
Obsolete
Microleakage, marginal corrosion, dimensional change. No longer indicated for root-end filling.
IRM / SuperEBA
Legacy
Better than amalgam, but inferior seal and biocompatibility versus bioceramics. Still used in some traditional offices.
MTA (mineral trioxide aggregate)
Standard
Hydrophilic, bioactive, induces cementogenesis. Long set time and handling difficulty are its main drawbacks.
Bioceramics (BC RRM, EndoSequence Putty)
Current
MTA-class biology with shorter set time and easier handling. Used as our primary root-end material.
Setzer & Kim (J Dent Res 2014) is the most rigorous side-by-side review of the two options. Headline findings worth knowing as a student or resident:
Patient-facing version of this same evidence: Save the tooth or get an implant — the long-term evidence
The papers and texts these protocols are built on. Read in roughly this order if you are new to the literature.
Outcome of Endodontic Surgery: A Meta-analysis — Part 1
Setzer FC, Shah SB, Kohli MR, Karabucak B, Kim S. J Endod. 2010;36(11):1757–1765.
Established the 94% vs. 59% success differential between endodontic microsurgery (EMS) and traditional root-end surgery (TRS) across 21 studies and 1,600+ cases.
Outcome of Endodontic Surgery: A Meta-analysis — Part 2
Setzer FC, Kohli MR, Shah SB, Karabucak B, Kim S. J Endod. 2012;38(1):1–10.
Showed the additional outcome benefit of high-magnification microsurgery (16–25×) over loupes — the gap is largest and most clinically meaningful for molars.
Long-Term Survival of Implants vs. Endodontically Treated Teeth
Setzer FC, Kim S. J Dent Res. 2014;93(1):19–26.
Critical review showing comparable long-term outcomes for implants and properly executed endodontic treatment, with significant publication and funding bias in the implant literature (63% non-disclosure of funding, 66% bias risk).
Modern Endodontic Surgery Concepts and Practice — A Review
Kim S, Kratchman S. J Endod. 2006;32(7):601–623.
The seminal review article that defined the modern microsurgical technique still in use today: small osteotomy, perpendicular resection, ultrasonic retro-preparation, microscope visualization.
Endodontics Review: A Study Guide
Blicher B, Lucier Pryles R, Lin J. Quintessence, 2016.
Concise board-style synthesis of the literature — diagnosis, treatment planning, instrumentation, irrigation, materials, surgery. The fastest way to build a structured mental model of the specialty.
Dr. Kung hosts a small number of dental students and pre-dental students each year for a half-day or full-day in the office. There is no cost.
Learn how to arrange a shadowing dayRelated: Evidence-based endodontics study guide · Research & Evidence · AAE Colleagues for Excellence newsletter archive · Our technology · Blog