Integrally molded dental appliance and process for its manufacture

In a hand-operable dental appliance including a hand piece mounting a rotary tool and further including a fluid pressure source for powering the tool, the improvement comprising:

• a unitary seamless body including an elongate handle portion and a generally barrel-shaped head portion extending transverse to said handle portion, said head portion having a cavity extending thereinto from one end of said head portion, said cavity having a generally circular cross section for receiving a rotary turbine assembly therein;
• one or more fluid communication conduits extending within said elongate handle portion of the body for fluid communication between a fluid pressure source and said cavity, said conduits being formed as interior elongate voids within said body wherein said interior surfaces of said body define outer surfaces of said conduits;
• and
• a rotary turbine assembly within said cavity, said turbine assembly including a rotatable spindle having a long axis, said spindle mounting an impeller for rotation of the latter when fluid under pressure is applied to one of said conduits with said other of said conduits exhausting said fluid under pressure, said turbine assembly further including a bearing assembly and an outer sleeve substantially enclosing said spindle, said impeller and said bearing assembly, with said bearing assembly fixedly mounted within said sleeve for rotation of said spindle mounting said impeller relative to said bearing assembly and said sleeve.

A method for manufacturing an integrally formed dental handpiece for drilling, shaping, finishing or polishing operations, the method comprising:

• providing a cavity mold having an elongate, angled central void;
• extending a mold probe of fusible material into either end of the cavity mold, one such mold probe including two elongate fingers and the other such mold probe including a generally cylindrical mass, said extending being performed in such manner that a tip of one of such elongate fingers contacts a side of such cylindrical mass in a predefined location;
• injecting a casting compound into the recesses formed between the fingers, the barrel and the cavity mold;
• curing the casting compound within the recesses;
• and
• heating the first and second probes to liquify the fusible material of which they are formed, thereby voiding interior regions within the cured casting compound to produce interconnected conduits extending from one end of the cured casting compound to the other.