It is difficult to remove the green line which is the hard plaque .You have to go to the dentist to get the cleaning done. You can try some dental school. if it is not possible then try to maintan very good oral hygeine by brushing twice a day regularly. You can try using the paste of baking soda and the hydrogen peroxide which may help you. but the best option is to go and get the cleaning done as this is going to effect your gums and you end up having the periodontitis with loose teeth. for more info on dental scaling you can visit the following link.........http://www.identalhub.com/articlecategory-dental-scaling-24.aspx