I have front teeth done as grown a fews year ago, now it have different color compare with my natural teeth, how i can fix it ? thanks

Crowns ?: If the color of the crowns no longer matches your natural teeth, the best way to fix it is to visit your dentist.

Whitening: If the crowns previously matched your natural teeth, your teeth have darkened since the crowns were placed. One possible treatment is to whiten your natural teeth slightly lighter than the shade of the crowns and then let your teeth "rebound" to a close match with the crowns. Another treatment is to whiten your natural teeth and then match new crowns to the shade of your teeth.

2 choices: If the crowns are lighter , you can try bleaching your natural teeth. If darker, probable crown replacement

See DDS: Difficult to comment without visualization. Are the crowns darker or lighter than your teeth? If the teeth are darker with age, bleaching may be an option, speak with your dentist for viability.

Color: Natural teeth will darken with age. Restorations (veneers, caps, etc) will not. Your Dentist may be able to bleach your natural teeth and/or redo the restorations for better color match.

Lightening: As we age the teeth will darken. See a dentist to discuss lightening your teeth so that everything matches.

Time for a redo: Unfortunately our teeth darken over time. this can be from the receding of the pulp deeper into the root, thinning of the enamel, accumulation of stains outside and within. This leaves the choices of professional "whitening", veneer or crown the other teeth to match the front teeth or redo the front teeth.

Depends: It depends upon the integrity of the crowns, how natural they look and what overall shade would best fit your smile. Same goes for the integrity, shade and health of the adjacent teeth. You need to be seen by your own dentist to discuss options, budget and expectations. There is no simple proper answer over the internet, sight unseen and without x-rays.

Options: You can either whiten your natural teeth or replace the work you had done on your front teeth to match your natural teeth.

I am guessing: that your natural teeth are now darker than the crowns... have the natural teeth whitened to better match the crowns.