An oral irrigator including a main body and a brush assembly. The semiconductor device includes spiral storage nodes disposed on a semiconductor substrate to vertically extend along spiral lines, a dielectric layer on the spiral storage nodes, and a plate node formed on the dielectric layer of the spiral storage nodes. The voltage source is configured to provide an output voltage out of the boosted supply voltage and based on the reference voltage. Each prosthesis may also have an articulating surface shaped such that, after attachment to the spine, the replaced or partially replaced facet joints provide a larger medial-lateral range of motion when the spine is flexed than when the spine is extended.