can affect your smile due to following reasons:-
During the procedure of putting the implant certain nerves responsible for movement of lower lip can be damaged(Partially, totally or just get stretched). this will cause defective movements of lower lip hence affecting you smile. It may take few weeks to as long as 18months for these damaged nerves to recover. besides movements lower lip can become numb(i.e. less sensation)
Also as lower lip and chin are part full expression of smile any change in shape and size will defenitely affect the overall smile which may or may not be better than you your original smile. An experienced cosmetic surgeon can help you to come to conclusion that whether the new smile will be more approprite and attractive than the present situtaion. There are many computer animations programs available to predict your future smile,
You must consider above mentioned points before undergoing surgery. Also you should have enough conviction and patience to undergo surgery and wait for final result. Cosmetic surgery is not suited for impatient and emotionalyy unstable personalities.