A dental handpiece assembly comprising: - a dental handpiece comprising: (a) a proximal end; (b) a distal end, the distal end including an attachment for assembly of a removable workpiece; (c) a handpiece body intermediate the proximal end and the distal end, the handpiece body having a gripping surface; the handpiece extending in a substantially axial direction along an axis that includes a portion of the distal end, the handpiece body and a portion of the proximal end; - a coupler including a cylinder portion and a supply-end portion, the cylinder portion assembled into the handpiece extending in the axial direction toward the distal end, the cylinder portion including at least one seal that interfaces with an interior of the body so as to isolate a portion of the body interior into at least one distinct chamber; wherein the supply-end portion of the coupler is configured to meet the requirements of the industry standard ISO 9168 and extends from the proximal end of the handpiece body at an angle from the axis, the supply-end portion including a plurality of outlets, the at least one distinct chamber in fluid communication with one of the outlets of the plurality of outlets, - an angled joint, the proximal end thereof including a threaded connection conforms to ISO standard 9168, wherein said angled joint is angled downward at a preselected angle from the axis of the handpiece, and is affixed over the proximal end of handpiece by: - molding onto the back end of the handpiece after the insertion of the coupler, or - permanently glueing onto the back end of the handpiece, or - screwing onto a threaded portion of the handpiece, or alternatively, the angled joint is manufactured integral with coupler, so that coupler is a single piece of metal, wherein angled joint is press fit or welded to handpiece. - a dental handpiece comprising: (a) a proximal end; (b) a distal end, the distal end including an attachment for assembly of a removable workpiece; (c) a handpiece body intermediate the proximal end and the distal end, the handpiece body having a gripping surface; the handpiece extending in a substantially axial direction along an axis that includes a portion of the distal end, the handpiece body and a portion of the proximal end; (a) a proximal end; (b) a distal end, the distal end including an attachment for assembly of a removable workpiece; (c) a handpiece body intermediate the proximal end and the distal end, the handpiece body having a gripping surface; the handpiece extending in a substantially axial direction along an axis that includes a portion of the distal end, the handpiece body and a portion of the proximal end; - a coupler including a cylinder portion and a supply-end portion, the cylinder portion assembled into the handpiece extending in the axial direction toward the distal end, the cylinder portion including at least one seal that interfaces with an interior of the body so as to isolate a portion of the body interior into at least one distinct chamber; - an angled joint, the proximal end thereof including a threaded connection conforms to ISO standard 9168, wherein said angled joint is angled downward at a preselected angle from the axis of the handpiece, and is affixed over the proximal end of handpiece by: - molding onto the back end of the handpiece after the insertion of the coupler, or - permanently glueing onto the back end of the handpiece, or - screwing onto a threaded portion of the handpiece, or alternatively, the angled joint is manufactured integral with coupler, so that coupler is a single piece of metal, wherein angled joint is press fit or welded to handpiece.