Is it permissible to have the teeth whitened by a dentist?
Question

                As per Our Islamic sharia it is not permissible to beautify the teeth. But What about the one whose teeth are yellowish (after brushing too) and wanted to clean the teeth going to a Dentist, so as to attend functions. Also let me clear You once if happend to clean the teeth spaces between the teeth will also occur.Plz need suddestions regarding tis. ** Alhamdulillah our website , queries of my various brothers and sisters and Your suggestions and answers made me to gain knowledge.
Praise be to Allah.
      There is nothing wrong with going to the dentist to have 
      the teeth cleaned and whitened; this is not regarded as changing the 
      creation of Allah, because the aim is to remove yellowness from the teeth 
      and restore them to their natural cleanness and whiteness. 

    The Messenger (blessings and peace of Allah be upon him) 
    encouraged using the siwaak, to purify and clean the mouth. He (blessings 
    and peace of Allah be upon him) said: “The siwaak is purifying to the mouth 
    and pleasing to the Lord.” Narrated by al-Nasaa’i (5); classed as saheeh by 
    al-Albaani in Saheeh al-Nasaa’i. 

    Shaykh al-Islam Ibn Taymyah (may Allah have mercy on him) 
    said, speaking of the places in which the recommendation to use the siwaak 
    is emphasised: 

    When the taste or smell in the mouth changes or the teeth 
    become yellow  or…, because of the report narrated by Tameem ibn al-‘Abbaas 
    who said: They came to the Prophet (blessings and peace of Allah be upon 
    him) and he said: “Why do I see you coming to me with yellow teeth? Use the 
    siwaak.” Narrated by Ahmad. End quote. 

    Sharh al-‘Umdah, 1/217-218 

    Ibn al-Atheer (may Allah have mercy on him) said in 
    al-Nihaayah (4/153): 

    Yellowness of the teeth refers to the yellow colour of the 
    teeth and dirt that gets onto them. This hadeeth encourages use of the 
    siwaak. End quote. 

    See: Nawaadir al-Usool, 1/186; al-Faa’iq fi Ghareeb 
    al-Hadeeth, 3/220 

    This hadeeth was classed as da‘eef (weak) in Silsilah 
    al-Ahaadeeth al-Da‘eefah (1748), but there are corroborating reports in 
    the hadeeths which indicate that it is prescribed to use the siwaak in order 
    to clean the mouth, such as the hadeeth of ‘Aa’ishah quoted above. 

    Al-Nawawi (may Allah have mercy on him) said: 

    The hadeeth of Tameem ibn al-‘Abbaas is da‘eef, but there is 
    no need for it as we have the evidence in the hadeeth, “The siwaak is 
    purifying to the mouth.” 

    End quote. Al-Majmoo‘, 1/325. 

    Then al-Nawawi (1/328) mentioned that one of the cases in 
    which it is confirmed that it is mustahabb to use the siwaak is if the teeth 
    look yellow. 

    Based on this, there is nothing wrong with going to the 
    dentist to have the teeth whitened and to remove the yellowish colour from 
    them. 

    And Allah knows best.