Impression tray for lower jaw

An impression tray for a lower jaw, comprising:

• a bottom portion which forms a U-shaped flat surface with an approximately uniform width;
• an outer wall which is inclined to an outer side of the impression tray via a circular arc shaped portion from an outer side of the bottom portion and is reduced its height in an end portion side of the U-shaped portion;
• an inner wall which is inclined to an inner side of the impression tray via a circular arc shaped portion from an inner side of said bottom portion;
• a rim having a height from 0.01 to 1 mm provided in said bottom portion along an upper end of said outer wall and an upper end of said inner wall;
• elongated through holes, each of which reaches said bottom portion from a portion just below said rim vertically and is formed as an elongated hole having a width from 1.5 to 4.0 mm, formed in such a manner that a distance between an adjacent pair of the elongated through holes is from 2 to 5 times the width of the elongated through hole;
• circular through holes provided in said bottom portion, each having a diameter from 3 to 6 mm and being positioned at the center of a distance between an adjacent pair of the elongated through holes which are provided in said outer wall and at the center of a distance between an adjacent pair of the elongated through holes which are provided in the inner wall;
• and
• bottom portion through holes, each of which has a width from 1.0 to 3.0 mm and a length from 5 to 15 mm and is formed as an elongated hole, formed on a line which connects the bottom portion side end portions of the respective elongated through holes positioned closest to the end portions of the U-shaped portion in said outer wall and the inner wall, or sides which are closer to the end portions than said line,
• wherein the impression tray is made of a plastic.