D2 · 20 min
Adhesive bonding
D2
HF, silane, etch, tack, glycerin — the lithium disilicate sequence in order.
This lesson’s protocol
Glass ceramic wants to be bonded, not luted. HF + silane on the porcelain, etch + adhesive on the tooth, resin cement in between. Skip a step and you have a very expensive temporary.
Lithium disilicate wants HF, silane, isolation, tack, then glycerin. Chemistry, not a lute.
Step 1 · Try-in with glycerin paste
Try-in with glycerin paste
In the mouth
Use a try-in paste, not the cement, to confirm shade and seat. Water-soluble. Rinse it completely. Never force a glass ceramic — it cracks instead of flexing.
From the lab
We often HF-etch and silanate in the lab. If the ticket says ‘already etched,’ do not guess — a second HF cycle over-etches and weakens the ceramic.
Why it exists
Shade of a translucent ceramic changes with the cement. Try-in paste is the rehearsal.
Read this
Glass wants chemistry
HF opens the glass. Silane couples it to resin. The tooth gets its own etch and adhesive. Skip isolation and you have a very expensive temporary. Check whether the lab already etched and silanated — a second HF cycle weakens the ceramic.
Tack, then clean, then cure
Full-cure before you clean and the excess is a glass flash in the embrasure. Tack two seconds, floss, peel the margin, glycerin, then the real cure.