An oral treatment device (200; 300; 400) comprising: a mouthpiece (201; 301; 401) comprising a curved wall (205; 305; 405) having a concave inner surface (213; 313; 413) and a bite platform (206; 306; 406) having an upper surface (207; 307; 407) and a lower surface (208; 308; 408) extending from the concave inner surface (213; 313; 413) of the curved wall (205; 305; 405) to a distal end (204; 304; 3404), the distal end (204; 304; 3404) of the bite platform (206; 306; 406) extending continuously in a non-interrupted manner from a first end (241; 341) of the bite platform (206; 306; 406) to a second end (242; 342) of the bite platform (206; 306; 406); wherein the bite platform (206; 306; 406) comprises a collapsible region (250; 350; 450) such that the mouthpiece (201; 301; 401) is alterable between: - a biased state in which the curved wall (205; 305; 405) has a first curvature; and - a flexed state in which the curved wall (205; 305; 405) has a second curvature that is different than the first curvature; wherein the bite platform (206; 306; 406) comprises the collapsible region (250; 350; 450) and at least one non-collapsible region (260, 270; 360; 460, 470), and wherein the non-collapsible region (260, 270; 360; 460, 470) of the bite platform (206; 306; 406) has a first thickness (TB1; TC1) measured from the lower surface (208; 308; 408) of the bite platform (206; 306; 406) to the upper surface (207; 307; 407) of the bite platform (206; 306; 406) and the collapsible region (250; 350; 450) of the bite platform (206; 306; 406) has a second thickness (TB2; TC2) measured from the lower surface (208; 308; 408) of the bite platform (206; 306; 406) to the upper surface (207; 307; 407) of the bite platform (206; 306; 406), characterized in that an electromagnetic radiation source (203; 303; 403) is configured to emit electromagnetic radiation from the curved wall (205; 305; 405), and in the first thickness (TB1; TC1) being greater than the second thickness (TB2; TC2). a mouthpiece (201; 301; 401) comprising a curved wall (205; 305; 405) having a concave inner surface (213; 313; 413) and a bite platform (206; 306; 406) having an upper surface (207; 307; 407) and a lower surface (208; 308; 408) extending from the concave inner surface (213; 313; 413) of the curved wall (205; 305; 405) to a distal end (204; 304; 3404), the distal end (204; 304; 3404) of the bite platform (206; 306; 406) extending continuously in a non-interrupted manner from a first end (241; 341) of the bite platform (206; 306; 406) to a second end (242; 342) of the bite platform (206; 306; 406); wherein the bite platform (206; 306; 406) comprises a collapsible region (250; 350; 450) such that the mouthpiece (201; 301; 401) is alterable between: - a biased state in which the curved wall (205; 305; 405) has a first curvature; and - a flexed state in which the curved wall (205; 305; 405) has a second curvature that is different than the first curvature; - a biased state in which the curved wall (205; 305; 405) has a first curvature; and - a flexed state in which the curved wall (205; 305; 405) has a second curvature that is different than the first curvature; wherein the bite platform (206; 306; 406) comprises the collapsible region (250; 350; 450) and at least one non-collapsible region (260, 270; 360; 460, 470), and wherein the non-collapsible region (260, 270; 360; 460, 470) of the bite platform (206; 306; 406) has a first thickness (TB1; TC1) measured from the lower surface (208; 308; 408) of the bite platform (206; 306; 406) to the upper surface (207; 307; 407) of the bite platform (206; 306; 406) and the collapsible region (250; 350; 450) of the bite platform (206; 306; 406) has a second thickness (TB2; TC2) measured from the lower surface (208; 308; 408) of the bite platform (206; 306; 406) to the upper surface (207; 307; 407) of the bite platform (206; 306; 406), characterized in that an electromagnetic radiation source (203; 303; 403) is configured to emit electromagnetic radiation from the curved wall (205; 305; 405), and in the first thickness (TB1; TC1) being greater than the second thickness (TB2; TC2).