Praise be to Allah, prayer and peace be upon the Messenger of Allah.
Shari`ah scholars drew a distinction between commercial insurance and Islamic takaful insurance. Commercial insurance is forbidden according to the majority of Muslim jurists (Fuqaha) and jurisprudence assemblies because it is a contract based on gambling and betting. Allah Said What means): “O You who have attained to faith! Intoxicants, and games of chance, and idolatrous practices, and the divining of the future are but a loathsome evil of Satan’s doing: shun it, then, so that you might attain to a happy state!..” {Al-Ma`idah/90}.
Islamic cooperative insurance based on the principle of interdependence (Takaful) ,cooperation and donation is valid from the stand point of Shari`ah . Allah, The Exalted, Said (What means): “Help one another to righteousness and piety; do not help one another to sin and enmity.” {Al-Ma`idah/2}. This view is adopted by the majority of jurisprudence assemblies and contemporary Iftaa` departments.
Although whoever aids in a commercial insurance contract is religiously sinful , the dentist is not since his relation with the insurance companies is a royalty or (Jo`alah) in Arabic .Therefore, he is allowed to make a contract whereby they agree to bring him patients for a certain amount of money that he pays to them. However, it would be better to simply deal with takaful insurance companies. And Allah knows best.