Truss Access Cavities: Practical Advantage or Clinical Compromise?

There has been a clear shift in endodontics over the last few years.

Preserve more dentine. Keep access cavities smaller. Make treatment more “conservative.”

But here’s the question that comes up chairside:

Are we trading off disinfection for dentine preservation?

A recent randomized controlled trial looked directly at this — comparing traditional access cavities (TEC) with truss access cavities (TREC) in mandibular molars.

What the Study Looked At

Patients were randomly assigned to either:

• Traditional Endodontic Cavity (TEC)

• Truss Endodontic Cavity (TREC)

Bacterial samples were taken before and after chemo-mechanical preparation using RT-qPCR analysis. Postoperative pain was recorded daily over 7 days using a visual analogue scale.

What Changed Clinically

Both groups showed a significant reduction in bacterial load after instrumentation.

However, the extent of reduction differed:

• TEC: ~96% bacterial reduction

• TREC: ~92% bacterial reduction

This difference was statistically significant.

In contrast, postoperative pain levels were similar in both groups, with no meaningful differences observed at any time point.

The findings suggest that access cavity design does influence disinfection.

With a traditional access:

• Instrumentation is more direct

• Irrigant penetration is more effective

• Debridement tends to be more complete

With a truss design:

• Access is more restricted

• Instrumentation becomes more technique-sensitive

• Certain areas of the canal system may be less accessible

While the numerical difference in bacterial reduction may appear modest, it becomes clinically relevant in cases where complete disinfection is already challenging.

TREC is designed to preserve dentine and potentially improve fracture resistance. That benefit is appealing, especially in structurally compromised teeth.

However, current evidence—including findings from this trial—suggests that:

• The improvement in fracture resistance may not always be significant

• The reduction in access can make cleaning more difficult

• The technique demands greater precision and operator experience

Importantly, the study also reinforces that access design does not influence postoperative pain, suggesting that patient comfort is unlikely to be affected by the choice of cavity design alone.

In a controlled setting, conservative access designs may be executed predictably.

In routine clinical practice, outcomes are influenced by:

• Visibility and magnification

• Canal anatomy

• Operator experience

• Availability of advanced instruments

In such situations, limited access may increase the risk of:

• Missed canals

• Incomplete debridement

• Procedural errors

Conservative access designs continue to evolve, but their clinical application requires careful case selection and appropriate expertise.

While preserving tooth structure remains an important goal, it should not compromise the primary objective of endodontic treatment—effective elimination of infection.

Conservation is valuable only when treatment objectives remain achievable

Truss access designs preserve a dentin bridge, but smaller access may reduce visualisation, straight-line access, canal detection and irrigant exchange. Laboratory fracture resistance or bacterial reduction does not by itself establish long-term clinical superiority. Access should be anatomy- and operator-specific, supported by magnification and imaging where indicated.

Compare instrumentation evidence, predictable endodontic workflows and post-endodontic restoration planning.

Frequently asked questions

Are truss accesses stronger than traditional accesses?

Laboratory results vary and do not yet prove better long-term tooth survival in every case.

When should they be avoided?

Avoid when restricted access threatens canal location, cleaning, procedural control or safe restoration.

Does smaller always mean minimally invasive?

No. An access that causes missed anatomy or complications is not biologically conservative.