A system for dispensing curable material, the system comprising: a housing ; a chamber coupled to the housing and defining a dispensing volume adapted to dispense the curable material; a first control surface coupled to the housing and adapted to receive an input from a user; a locking nut disposed within the housing and comprising internal threads ; and a lead screw rotatably fixed relative to the first control surface with the lead screw comprising a proximal end , a distal end , external threads at least partially disposed between the proximal and distal ends , and a translation axis (TA) defined between the proximal and distal ends with engagement between the external threads of lead screw and the internal threads of the locking nut adapted to provide for movement of the lead screw along the translation axis to compress the curable material within the dispensing volume ; and a defeatable unidirectional mechanism operably coupling the first control surface and the housing , characterised in that the defeatable unidirectional mechanism is adapted to (i) permit for distal advancement of the lead screw in response to the first control surface receiving a first input torque in a first direction (R1) about the translation axis that is below a torque threshold, (ii) prevent proximal movement of the lead screw in response to the first control surface receiving a second input torque in a second direction (R2) opposite the first direction that is less than the torque threshold, and (iii) permit proximal movement of the lead screw with rotation of the first control surface in the second direction in response to the first control surface receiving the second input torque that is at least equal to the torque threshold. a housing ; a chamber coupled to the housing and defining a dispensing volume adapted to dispense the curable material; a first control surface coupled to the housing and adapted to receive an input from a user; a locking nut disposed within the housing and comprising internal threads ; and a lead screw rotatably fixed relative to the first control surface with the lead screw comprising a proximal end , a distal end , external threads at least partially disposed between the proximal and distal ends , and a translation axis (TA) defined between the proximal and distal ends with engagement between the external threads of lead screw and the internal threads of the locking nut adapted to provide for movement of the lead screw along the translation axis to compress the curable material within the dispensing volume ; and a defeatable unidirectional mechanism operably coupling the first control surface and the housing , characterised in that the defeatable unidirectional mechanism is adapted to (i) permit for distal advancement of the lead screw in response to the first control surface receiving a first input torque in a first direction (R1) about the translation axis that is below a torque threshold, (ii) prevent proximal movement of the lead screw in response to the first control surface receiving a second input torque in a second direction (R2) opposite the first direction that is less than the torque threshold, and (iii) permit proximal movement of the lead screw with rotation of the first control surface in the second direction in response to the first control surface receiving the second input torque that is at least equal to the torque threshold. <EOS>