If Teeth Are Very Yellow or Discoloured, How Much Can All-ceramic Veneers Mask?｜證據鏈

All-ceramic veneers can alter the lightness, chroma and hue of teeth, but there is no universal answer to ‘what proportion can be masked?’. The final colour results from the combined effects of the original tooth substrate shade, ceramic thickness and translucency, bonding material and the technician’s layering. The darker and less evenly distributed the substrate shade, the harder it is for a very thin, highly translucent veneer alone to mask it unobtrusively. Increasing preparation and opacity purely for masking may sacrifice healthy enamel or make the appearance look flat. If a single tooth has darkened after root canal treatment, the tooth and root canal status should first be confirmed, then internal bleaching assessed to see whether it can make the substrate shade easier to manage. One systematic review included 8 studies, of which 6 could enter the meta-analysis. Both shade-guide scores and instrumental colour differences changed significantly after internal bleaching, but the studies had a moderate to high risk of bias and more follow-up is still needed on long-term colour stability. For deep drug-related, banded or multiple-tooth discolouration, the extent and depth should first be identified, followed by a comparison of bleaching, veneers or combined treatment, rather than selecting the ‘whitest’ ceramic first.