If a tooth is in the early stages of decay fillings are needed. Left unchecked, the decay begins to spread to the root and damages the tooth 's inner nerve. It causes extreme pain and potential infection and a root canal must be performed at this stage. This is why treating the deteriorating tooth at the early stages is critical, thus preventing the impact of deeper treatments. Composite fillings are tinted to match the colour of your tooth enamel, so that after the filling is applied your restored tooth should appear white and normal.