A bite block, an illumination device having a saliva suction function, and a TIPS for protecting the tongue of a patient are disclosed. The present invention guides the tongue of the patient such that when dental treatment is performed, the tongue of the patient can be safely and comfortably protected. Furthermore, saliva collected around the throat of the patient can be rapidly removed so that the patient feels little foreign-body like sensations. In addition, the TIPS can isolate the tongue from one side of the mouth cavity to be treated so as to ensure space for treatment. Moreover, the present invention can illuminate the entirety of the mouth cavity of the patient to enable a doctor to conveniently conduct the dental treatment.