RONDOflex: why a finishing step matters before a filling

Key points

• RONDOflex is more often used after the bur than instead of it, as a final surface preparation.
• The bur leaves a smear layer: enamel and dentine debris, bacteria and saliva that clog the dentinal tubules.
• Adhesive cannot penetrate clogged tubules, so the bond between filling and tooth is weaker.
• Some situations need no drilling at all: cervical (abfraction) lesions and small surface defects.
• The clinician decides the approach after examination, based on the extent of damage and tissue condition.

What the bur does, and why it is not enough

The bur removes damaged tooth tissue and shapes the cavity for the future filling. In deep caries or when replacing an old restoration, this step cannot be skipped.

But a rotating instrument inevitably leaves a smear layer on the surface — a mixture of fine enamel and dentine particles, bacteria and saliva. It clogs the microscopic dentinal tubules to a depth of up to forty microns.

The easiest comparison: the pores of a brick filled with concrete. The surface is smooth, but it can no longer absorb anything.

What RONDOflex adds

RONDOflex delivers a very fine stream of powder under pressure. Without vibration or heat, in five to ten seconds it clears the contaminated layer from the tubules, roughens the surface and removes bacterial residue from the cavity.

After this, the adhesive penetrates into the tissue instead of sitting on top of it. The bond between filling and tooth is stronger, and the marginal seal is tighter.

When drilling genuinely is not needed

There are clinical situations where RONDOflex works as a standalone instrument and no bur is used.

These are cervical lesions — tissue erosion at the neck of the tooth — and small surface defects where only surface preparation is required. In such cases preparation proceeds without noise, without vibration and, where conditions allow, without anaesthesia.

Deep caries: why this matters most

The most demanding situation is when fractions of a millimetre remain above the nerve. Here the bur removes the bulk of the damaged tissue and RONDOflex completes the work.

The powder stream clears the remaining infected dentine without heat or pressure on the pulp. Where a bur advances at the risk of exposing the nerve, the air-abrasive stream reaches more gently. It is one way of keeping a tooth vital, though the outcome depends on the depth of the lesion and the state of the pulp, which the clinician assesses individually.

What this changes for the patient

A tight marginal seal reduces the risk of secondary caries under the filling — the situation where decay continues beneath the restoration and is hard to spot.

The finishing stage has no drilling noise and no vibration, so this part of the appointment is calmer.

Whether the method suits your case, and to what extent, is determined after examination. The extent of damage, the condition of the tissue and the position of the defect differ for every patient.

Frequently asked questions

Is RONDOflex dentistry without drilling?

Not always. For cervical lesions and small surface defects the unit may be used on its own. In deep caries and when replacing old restorations it complements the bur at the finishing stage rather than replacing it.

Does it hurt?

The treatment produces no vibration and no heat, so this stage is easier to tolerate than drilling. In some cases preparation is possible without anaesthesia — the clinician decides based on the clinical situation.

What is the smear layer?

A layer of fine enamel and dentine particles, bacteria and saliva left on the surface after work with a rotating instrument. It clogs the dentinal tubules and prevents adhesive from penetrating.

If the filling holds anyway, why remove the smear layer?

Adhesive bonds to the tooth by penetrating the dentinal tubules. If they are clogged, the bond is weaker, and over time the risk of secondary caries at the filling margin increases.

Does the method suit a cervical lesion?

Cervical lesions are one of the indications where preparation without a bur is possible. The extent of treatment is determined after examination.

Sources used to prepare this guide

Content updated: 2026-07-31

• Dental caries: prevention and management — American Dental Association