An adjustable bite block, for a mouth of a patient, used during a medical or surgical procedure, comprising: an upper portion for engagement or abutment with teeth of a maxilla of said patient, the upper portion adjoining or rigidly connected to a generally cylindrical passageway portion; a lower portion for engagement or abutment with teeth of a mandible of said patient, the lower portion being movable relative to the upper portion; at least one passageway extending through said passageway portion; and a generally annular adjustment member being engageable with said passageway portion, the adjustment member coupled to, or engaging, the lower portion of the bite block, whereby in use the adjustment member being accessible from an exterior of the mouth of said patient and being configured to move the lower portion relative to the upper portion, to thereby move the mandible of the patient; characterised by the passageway portion including a thread on, or in, an outer surface thereof and the adjustment member being configured to engage over said passageway portion, the adjustment member including an outer grip surface and an inner thread being configured to cooperate with said thread of the passageway portion; wherein the lower portion being coupled to, and movable by, said adjustment member, such that rotation of the adjustment member around the passageway portion causes the lower portion to move relative to the upper portion, to thereby move the mandible of said patient during use; and wherein the adjustment member being accessible from an exterior of the mouth of said patient, when the bite block being positioned therein and extending therefrom, whereby the lower portion being movable by way of the adjustment member, whilst a scope, or a flexible tube, or another medical device, is positioned through said passageway portion. an upper portion for engagement or abutment with teeth of a maxilla of said patient, the upper portion adjoining or rigidly connected to a generally cylindrical passageway portion; a lower portion for engagement or abutment with teeth of a mandible of said patient, the lower portion being movable relative to the upper portion; at least one passageway extending through said passageway portion; and a generally annular adjustment member being engageable with said passageway portion, the adjustment member coupled to, or engaging, the lower portion of the bite block, whereby in use the adjustment member being accessible from an exterior of the mouth of said patient and being configured to move the lower portion relative to the upper portion, to thereby move the mandible of the patient; characterised by the passageway portion including a thread on, or in, an outer surface thereof and the adjustment member being configured to engage over said passageway portion, the adjustment member including an outer grip surface and an inner thread being configured to cooperate with said thread of the passageway portion; wherein the lower portion being coupled to, and movable by, said adjustment member, such that rotation of the adjustment member around the passageway portion causes the lower portion to move relative to the upper portion, to thereby move the mandible of said patient during use; and wherein the adjustment member being accessible from an exterior of the mouth of said patient, when the bite block being positioned therein and extending therefrom, whereby the lower portion being movable by way of the adjustment member, whilst a scope, or a flexible tube, or another medical device, is positioned through said passageway portion.