Nearly every effective aligner case uses them, nobody warns you about them, and they're the reason plastic trays can perform movements that once needed metal. Meet the attachments.
Attachments are small shapes of tooth-coloured composite (the white-filling material) bonded to specific teeth for the duration of treatment — typically 1–3mm, in geometric shapes chosen by the planning software. The problem they solve: smooth plastic on smooth enamel can push teeth sideways but can't grip. Rotating a rounded premolar, pulling a tooth downward, controlling a root's angle — these need a handle. The attachment is the handle; the aligner clicks over it and applies force with a precision flat plastic can't achieve (the full mechanics).
You can ask, and for very simple cases the answer may genuinely be yes. But understand the trade: refusing attachments in a case that needs them means movements happen slower, less predictably, or not at all — it's a leading cause of treatments needing refinement rounds. Mail-order aligner brands skip attachments because nobody is there to bond them — which is precisely why they can't handle rotations or vertical movements (the comparison). If your digital plan includes attachments, they're load-bearing, not optional extras.
Typically 6–20 across the arch, decided tooth-by-tooth by the digital plan. Simple spacing cases may need very few; rotations and bite corrections need more. You see the exact map on your plan before committing.
No — they bond to the enamel surface the same way white fillings do and are polished off completely afterwards. The conditioning involved is superficial and standard restorative practice.
At conversation distance with trays in: no. Trays out, up close in bright light: as faint tooth-coloured bumps. They're dramatically less visible than the ceramic brackets people compare them against.
Free assessment — your digital plan shows exactly which teeth need attachments before you decide anything.