Getting a precise match and creating symmetry can be very challenging and require a highly skilled and artistic clinician. The easiest and most affordable way is to try whitening your tooth and adjacent teeth to help get a closer color match - assuming the "rebuilt part" is composite or a porcelain veneer. These will not change color if you whiten your teeth. Ask your dentist what are the best options for you - in-office whitening, take-home custom trays or prefabricated/over-the-counter products. However this would not address your concern of the rebuilt tooth looking bigger. Another possibility is to have your dentist replace the new restoration with a shade darker, and to reshape it to appear somewhat smaller. If none of these approaches are effective, you may want to consider restoring 2-4 teeth with composite bonding or veneers, especially if there is also a size discrepancy. This will assure that the teeth will all be uniform in size and color. I would suggest having a diagnostic wax-up mockup of the end result prior to committing to any treatment. Hope this helps, good luck!
