RDA (Other exams): Etchant Left on a Subgingival Class II

Isolation and hemostasis come first because contamination, not the bonding technique, is what fails these restorations.

• Wedge and matrix placed before etch. The wedge seals the gingival margin of the band; bonding a margin you cannot see or keep dry is the classic cause of a stained, leaking distal box.
• Hemostasis before etch, not after. Astringent hemostatic agents need working time and then must be rinsed away; residual ferric sulfate or aluminum chloride left under a bond inhibits polymerization. The order is: place wedge, apply hemostatic with gentle pressure, allow the labelled time, suction, rinse, then isolate and etch.
• Warfarin changes technique, not the plan. He is therapeutically anticoagulated, so pack and retract gently, avoid nicking the gingiva, and expect slow oozing that takes longer to control. Do not use an epinephrine-containing cord without the dentist's decision - check the cardiac history as well as the INR.
• Rubber dam or at minimum a split-dam/isolating system on #30, with high-volume suction and a saliva ejector.
• Anticipate the gag reflex: place the dam quickly, keep the frame off the lip, and keep the appointment moving rather than leaving him open-mouthed during a phone call.

Rinse first, diagnose second, and do not improvise a re-etch.

• Rinse thoroughly and immediately with air-water spray, with suction, for the full manufacturer-recommended time. A five-minute contact is well beyond any intended etch.
• Do not dry the dentin. Over-etched dentin can collapse its collagen network; aggressive air-drying makes that worse. Blot, do not desiccate, and let the dentist decide on the bonding protocol - some systems call for a re-wet or a specific primer technique after prolonged etch.
• Do not re-etch blindly. If the field was contaminated by saliva or blood during the call, enamel needs re-etching (roughly 15 seconds after re-isolation). Dentin does not need a second aggressive etch.
• Tell the dentist exactly what happened - the likely contact time, what was contaminated, what the tissue looks like. This is their clinical call, and they cannot make it without accurate information.
• Fix the bleeding before bonding. If the distal sulcus is still oozing, stop and re-establish hemostasis; bonding over crevicular fluid will fail regardless of what happens with the etch.
• Chart the event and the dentist's management decision.

Match the matrix to the box, then verify the seal.

• A sectional matrix with a separating ring suits a MOD on a molar with a subgingival distal box. It follows the gingival contour, gives a tighter proximal contact than a flat Tofflemire band, and the ring provides the separation that compensates for the missing proximal wall.
• A Tofflemire is the weaker choice here precisely because of the subgingival margin: a straight band tends to bridge over the box and leave a gap or a flat, open contact.
• Wedge selection: size the wedge to the embrasure rather than forcing a large one, place it from the wider lingual embrasure if access is better, and use it both to adapt the band to the tooth and to gain slight separation. A light-transmitting wedge is worth having out if the dentist cures interproximally.
• Checks before the etch: the band's gingival edge is not folded or short of the margin, the ring is seated without springing the band, the wedge is stable, and the distal margin is actually visible. If it is not visible, say so before etching - the dentist may need to place retraction cord or adjust the margin first.
• Have the next instrument ready (burnisher, interproximal carver, floss) so the call does not stall the appointment and the patient is not left open-mouthed.