An impression technique to make a new master existing removable partial denture Philip
J. Render,
cast for an
DMD*
Brooke Army Medical Center, San Antonio, Tex. When the master cast for a removable partial denture is lost and a well-fitting framework remains, it may be necessary to replace the master cast. A two-step impression procedure is described that combines the altered-cast technique and the use of a modified disposable tray. Finger pressure is maintained on the major connector throughout the making of both impressions, to prevent framework movement and loss of contact with prepared rest seats. (J PROSTHET DENT 1992;67:488-90.)
D*
lfficult situations that a prosthodontist may encounter are (1) the loss of a master cast for a removable partial framework and (2) the need to replace the acrylic resin of the base of an existing removable partial denture. Making an impression with the framework in place may result in a cast with the framework not in its originally designed position. With an extension removable partial denture framework, the pressure of the impression material on the spared latticework tends to rotate the framework and unseat an indirect retainer that may be present (Fig. 1). A technique using digital pressure to maintain the seat The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflect.ing the views of the Department of the Army or the Department of Defense. aColonel, U. S. Army, DC, Commander, Area Dental Laboratory, San Antonio, Tex. 10/l/27155
Fig. 2. Beading wax is added to latticework.
FRAMEWORK ROTATED OUT OF ‘DESIGN POSITION’ NON FUNCTIONAL INDIRECT RETAINER
Fig. 1. Framework rotation that can occur during impression making.
488
Fig. 3. Irreversible hydrocolloid.
Fig. 4. Completed impression tray. Note finger position that is used intraorally to keep rests and indirect retainers seated during impression making.
Fig. 5. Completed impression,
Fig. 6. Cutback of disposable tray eliminates impression pressure on distal-extension base and allows finger access to major connector.
Fig. 7. Major connector painted with irreversible hydrocolloid adhesive.
of the framework during the impression making is described.
PROCEDURE Attach beading wax to the spared latticework as necessary to protect the patient from sharp edges (Fig. 2) and fully seat the framework. Continue fitting the framework by physiologically adjusting it for rotation. Make an impression with the framework in place using irreversible hydrocolloid (Fig. 3) and pour a cast. Outline the extent of an impression tray on the cast and construct an autopolymerizing acrylic resin tray as in the altered-cast technique (Fig. 4).l Grind away the inner surface of the tray until the metal framework is exposed. Paint the tray with pressure indicating paste (Mizzy, Inc., Clifton Forge, Va.) and seat the framework in the mouth. Relieve any pressure spots.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 8. Finger pressure maintained on framework during making of second impression.
489
Fig.
4. Make a border-molded impression by using modeling plastic and an elastomeric impression material. Maintain finger pressure on the major connector anterior to the fulcrum line (Figs. 4 and 5). 5. Shorten an appropriate disposable tray so that it covers only the region of the teeth. Cut the tray back on the lingual midline to allow accessfor finger pressure when making a second impression (Fig. 6). 6. Paint the lingual surface of the major connector with an irreversible hydrocolloid adhesive (Hold, Teledyne Getz, Inc., Elk Grove Village, Ill.) to bond the two impressions together (Fig. 7). Seat the framework in the mouth and apply finger pressure. Fill the second tray with irreversible hydrocolloid and insert in the mouth around the supporting finger (Fig. 8). After setting, remove the two-part impression in one piece by applying unseating force on the labial flanges (Fig. 9). Pour a cast and separate (Fig. 10).
9. Completed impression.
SUMMARY A technique is described for replacing a lost removable partial denture master cast. Its chief advantage is that using digital pressure assures full seating of the framework during making of the impression. REFERENCE 1. Leopold F&J,Kratochvil FJ. Au altered cast procedureto improve tiaaue support for removablepartial dentures.J PROSTHET DENT1965; 15~6’72-8.
Fig.
Reprint requeststo: DR. PHILIPJ. RENDER 1005GORGAS CIRCLE SANANTONIO, TX 16234
10. Replaced master cast.
Availability
of JOURNAL
back
issues,
1986-1991
Back issues of THE JOURNAL OF PROSTHETIC DENTISTRY are available for purchase from the publisher, Mosby-Year Book, Inc., at a cost of $7.00 per issue. (Foreign postage is not included.) The following quantity discounts are available: 25% off on quantities of 12 to 23, and one third off on quantities of 24 or more. Please write to Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, MO 63146-3318, or call (800)325-4177, ext. 4351, or (314)453-4351 for information on availability of particular issues for that period from 1980 to 1991. If unavailable from the publisher, photocopies of complete issues are available from University Microforms International, 300 N. Zeeb Rd., Ann Arbor, MI 48106, (313)761-4700.
490
APRIL
1022
VOLUME
67
NUMBER
4
J. Render,
cast for an
DMD*
Brooke Army Medical Center, San Antonio, Tex. When the master cast for a removable partial denture is lost and a well-fitting framework remains, it may be necessary to replace the master cast. A two-step impression procedure is described that combines the altered-cast technique and the use of a modified disposable tray. Finger pressure is maintained on the major connector throughout the making of both impressions, to prevent framework movement and loss of contact with prepared rest seats. (J PROSTHET DENT 1992;67:488-90.)
D*
lfficult situations that a prosthodontist may encounter are (1) the loss of a master cast for a removable partial framework and (2) the need to replace the acrylic resin of the base of an existing removable partial denture. Making an impression with the framework in place may result in a cast with the framework not in its originally designed position. With an extension removable partial denture framework, the pressure of the impression material on the spared latticework tends to rotate the framework and unseat an indirect retainer that may be present (Fig. 1). A technique using digital pressure to maintain the seat The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as reflect.ing the views of the Department of the Army or the Department of Defense. aColonel, U. S. Army, DC, Commander, Area Dental Laboratory, San Antonio, Tex. 10/l/27155
Fig. 2. Beading wax is added to latticework.
FRAMEWORK ROTATED OUT OF ‘DESIGN POSITION’ NON FUNCTIONAL INDIRECT RETAINER
Fig. 1. Framework rotation that can occur during impression making.
488
Fig. 3. Irreversible hydrocolloid.
Fig. 4. Completed impression tray. Note finger position that is used intraorally to keep rests and indirect retainers seated during impression making.
Fig. 5. Completed impression,
Fig. 6. Cutback of disposable tray eliminates impression pressure on distal-extension base and allows finger access to major connector.
Fig. 7. Major connector painted with irreversible hydrocolloid adhesive.
of the framework during the impression making is described.
PROCEDURE Attach beading wax to the spared latticework as necessary to protect the patient from sharp edges (Fig. 2) and fully seat the framework. Continue fitting the framework by physiologically adjusting it for rotation. Make an impression with the framework in place using irreversible hydrocolloid (Fig. 3) and pour a cast. Outline the extent of an impression tray on the cast and construct an autopolymerizing acrylic resin tray as in the altered-cast technique (Fig. 4).l Grind away the inner surface of the tray until the metal framework is exposed. Paint the tray with pressure indicating paste (Mizzy, Inc., Clifton Forge, Va.) and seat the framework in the mouth. Relieve any pressure spots.
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 8. Finger pressure maintained on framework during making of second impression.
489
Fig.
4. Make a border-molded impression by using modeling plastic and an elastomeric impression material. Maintain finger pressure on the major connector anterior to the fulcrum line (Figs. 4 and 5). 5. Shorten an appropriate disposable tray so that it covers only the region of the teeth. Cut the tray back on the lingual midline to allow accessfor finger pressure when making a second impression (Fig. 6). 6. Paint the lingual surface of the major connector with an irreversible hydrocolloid adhesive (Hold, Teledyne Getz, Inc., Elk Grove Village, Ill.) to bond the two impressions together (Fig. 7). Seat the framework in the mouth and apply finger pressure. Fill the second tray with irreversible hydrocolloid and insert in the mouth around the supporting finger (Fig. 8). After setting, remove the two-part impression in one piece by applying unseating force on the labial flanges (Fig. 9). Pour a cast and separate (Fig. 10).
9. Completed impression.
SUMMARY A technique is described for replacing a lost removable partial denture master cast. Its chief advantage is that using digital pressure assures full seating of the framework during making of the impression. REFERENCE 1. Leopold F&J,Kratochvil FJ. Au altered cast procedureto improve tiaaue support for removablepartial dentures.J PROSTHET DENT1965; 15~6’72-8.
Fig.
Reprint requeststo: DR. PHILIPJ. RENDER 1005GORGAS CIRCLE SANANTONIO, TX 16234
10. Replaced master cast.
Availability
of JOURNAL
back
issues,
1986-1991
Back issues of THE JOURNAL OF PROSTHETIC DENTISTRY are available for purchase from the publisher, Mosby-Year Book, Inc., at a cost of $7.00 per issue. (Foreign postage is not included.) The following quantity discounts are available: 25% off on quantities of 12 to 23, and one third off on quantities of 24 or more. Please write to Mosby-Year Book, Inc., Subscription Services, 11830 Westline Industrial Drive, St. Louis, MO 63146-3318, or call (800)325-4177, ext. 4351, or (314)453-4351 for information on availability of particular issues for that period from 1980 to 1991. If unavailable from the publisher, photocopies of complete issues are available from University Microforms International, 300 N. Zeeb Rd., Ann Arbor, MI 48106, (313)761-4700.
490
APRIL
1022
VOLUME
67
NUMBER
4
