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A simplified technique for intraoral undercut blockout before impression procedures
dercut Philip
S. Baker,
bloekou
eatty,
University of Florida, Collegeof Dentistry, Gainesville, Fla. Many different methods of blocking out hard tissueundercuts have been described to eliminate distortion and tearing of set impression materials and minimize the trauma of removal of impressions to intraoral tissues. These methods range from the use of wet facial tissue to polyether impressionmaterial.le4
The ideal blockout material should (1) be quickly and easily placed, (2) maintain positional stability during impression procedures, (3) be easily removed, and (4) be compatible with the impressionmaterials use This article describesa simplified technique for intraoral undercut blockout and gives examples of its use in two commonclinical situations. TECHNIQUE
*Assistant **Associate
Fig.
Professor, Professor,
Departmen; Department
of Prosthodontics. of Endodontics.
1. Patient exhibiting large tnterproximal embra-
Equal lengths of Nogenol (Coe Laboratories, Chicago Ill.) temporary cement baseand catalyst pastes of suffi-
sures.
3. Patient with highly mobile remaining maxillary teeth requiring immediate complete denture treatment.
2. Placement of temporary cement into embrasures with syringe.
ig. 4. Temporary cement placed to block out mr,erproximal undercuts.
Fig.
116
Fig.
TIPS FROM
OUR
READERS
cient quantity to fill the undercuts are dispensed on a disposable mixing pad. The base and catalyst are mixed for 30 seconds, loaded into a plastic disposable impression syringe barrel, and the plunger is inserted into the syringe. The involved tissues are then dried with air or gauze pads. The temporary cement is dispensed into the desired regions and allowed to set, with a dry field maintained at least until the material has set in 3 to 5 minutes. If acrylic resin or composite resin restorations are present, a light coating of petroleum jelly on these materials before cement application will ensure rapid cleanup. After the impression procedures are completed, the temporary cement is easily removed with a scaler or plastic instrument. Knotted dental floss may also be used interproximally or under pontics as needed. CLINICAL
EXAMPLES
Large interproximal embrasures, splinted teeth, pontics, and bars Often these hard tissue/prosthetic undercuts present a significant obstacle to successful impressions (Fig. 1). The temporary cement should be injected into these dried regions from the facial and lingual directions, joining both facial and lingual segments before the cement has begun to set (Fig. 2). Excess set cement may be easily removed by gentle contouring with a scaler.
sibility of inadvertant extraction during such impression procedures is often intimidating to the dentist and frightening to the patient. Where tooth mobility is less marked, temporary cement can be injected into the interproximal regions as previously described, with some slight stabilizing effect gained from placement between adjacent teeth (Fig. 4). In patients requiring maximum stabilization, composite resin may be used to unite the contacts by acid-etch techniques and may serve as a provisional fixed splint, with temporary cement filling the remaining embrasure spaces during impression procedures. REFERENCES 1. Heintz
WD. Symposium on common failures in removable partial prosthodontics. Dent Clin North Am 1979;23:11. 2. Rudd KD, Morrow RM, Eissmann HF. Dental laboratory procedures: removable partial dentures. vol 3, 1st ed. St Louis: CV Mosby Co, 1981;580.
3. Winkler S, Gray SA. Blockout before making impressions of bars. J PROSTHET DENT 1986,56:258. 4. Gerrow JD, Jons R. Use of polyvinyl siloxane as blackout material during indirect placement of overdenture attachments. J PR~BTHET DENT 1986;56:510-12. Reprint requests to: DR. PHILIP S. BAKER UN~VW~~~Y OF FLORIDA COLLECE OF DENTISTRY
Box 5435 JHMHSC
Mobile teeth Excessively mobile teeth are often seen in patients requiring immediate complete dentures (Fig. 3). The pos-
Removing
(.hINI?.SVILLE,
FL 32610
debris from dowel pin holes
Edwin B. Walker, D.D.S. Mountain City, Tenn. Debris that becomes lodged in the dowel pin hole of a working cast is difficult to remove and prevents complete seating of the die. To dislodge interfering debris from the dowel receptacle, the brushes shown in Fig. 1 are small enough to pass through the hole in the stone and the bristles are stiff enough to remove stone chips and wax particles. The small brushes are available from Small Parts, Inc., 6901 N.E. Third Ave., P.O. Box 381966, Miami, FL 332381736.
Reprint requests to: DR. EDWIN B. WALKER ROUTE 1 P.O. Box 150 MOUNTAIN CITY, TN 37683
TEE
JOURNAL
OF PROSTHETIC
Fig. 1. Brushes for removing debris from dowel pin holes.
DENTISTRY
117
S. Baker,
bloekou
eatty,
University of Florida, Collegeof Dentistry, Gainesville, Fla. Many different methods of blocking out hard tissueundercuts have been described to eliminate distortion and tearing of set impression materials and minimize the trauma of removal of impressions to intraoral tissues. These methods range from the use of wet facial tissue to polyether impressionmaterial.le4
The ideal blockout material should (1) be quickly and easily placed, (2) maintain positional stability during impression procedures, (3) be easily removed, and (4) be compatible with the impressionmaterials use This article describesa simplified technique for intraoral undercut blockout and gives examples of its use in two commonclinical situations. TECHNIQUE
*Assistant **Associate
Fig.
Professor, Professor,
Departmen; Department
of Prosthodontics. of Endodontics.
1. Patient exhibiting large tnterproximal embra-
Equal lengths of Nogenol (Coe Laboratories, Chicago Ill.) temporary cement baseand catalyst pastes of suffi-
sures.
3. Patient with highly mobile remaining maxillary teeth requiring immediate complete denture treatment.
2. Placement of temporary cement into embrasures with syringe.
ig. 4. Temporary cement placed to block out mr,erproximal undercuts.
Fig.
116
Fig.
TIPS FROM
OUR
READERS
cient quantity to fill the undercuts are dispensed on a disposable mixing pad. The base and catalyst are mixed for 30 seconds, loaded into a plastic disposable impression syringe barrel, and the plunger is inserted into the syringe. The involved tissues are then dried with air or gauze pads. The temporary cement is dispensed into the desired regions and allowed to set, with a dry field maintained at least until the material has set in 3 to 5 minutes. If acrylic resin or composite resin restorations are present, a light coating of petroleum jelly on these materials before cement application will ensure rapid cleanup. After the impression procedures are completed, the temporary cement is easily removed with a scaler or plastic instrument. Knotted dental floss may also be used interproximally or under pontics as needed. CLINICAL
EXAMPLES
Large interproximal embrasures, splinted teeth, pontics, and bars Often these hard tissue/prosthetic undercuts present a significant obstacle to successful impressions (Fig. 1). The temporary cement should be injected into these dried regions from the facial and lingual directions, joining both facial and lingual segments before the cement has begun to set (Fig. 2). Excess set cement may be easily removed by gentle contouring with a scaler.
sibility of inadvertant extraction during such impression procedures is often intimidating to the dentist and frightening to the patient. Where tooth mobility is less marked, temporary cement can be injected into the interproximal regions as previously described, with some slight stabilizing effect gained from placement between adjacent teeth (Fig. 4). In patients requiring maximum stabilization, composite resin may be used to unite the contacts by acid-etch techniques and may serve as a provisional fixed splint, with temporary cement filling the remaining embrasure spaces during impression procedures. REFERENCES 1. Heintz
WD. Symposium on common failures in removable partial prosthodontics. Dent Clin North Am 1979;23:11. 2. Rudd KD, Morrow RM, Eissmann HF. Dental laboratory procedures: removable partial dentures. vol 3, 1st ed. St Louis: CV Mosby Co, 1981;580.
3. Winkler S, Gray SA. Blockout before making impressions of bars. J PROSTHET DENT 1986,56:258. 4. Gerrow JD, Jons R. Use of polyvinyl siloxane as blackout material during indirect placement of overdenture attachments. J PR~BTHET DENT 1986;56:510-12. Reprint requests to: DR. PHILIP S. BAKER UN~VW~~~Y OF FLORIDA COLLECE OF DENTISTRY
Box 5435 JHMHSC
Mobile teeth Excessively mobile teeth are often seen in patients requiring immediate complete dentures (Fig. 3). The pos-
Removing
(.hINI?.SVILLE,
FL 32610
debris from dowel pin holes
Edwin B. Walker, D.D.S. Mountain City, Tenn. Debris that becomes lodged in the dowel pin hole of a working cast is difficult to remove and prevents complete seating of the die. To dislodge interfering debris from the dowel receptacle, the brushes shown in Fig. 1 are small enough to pass through the hole in the stone and the bristles are stiff enough to remove stone chips and wax particles. The small brushes are available from Small Parts, Inc., 6901 N.E. Third Ave., P.O. Box 381966, Miami, FL 332381736.
Reprint requests to: DR. EDWIN B. WALKER ROUTE 1 P.O. Box 150 MOUNTAIN CITY, TN 37683
TEE
JOURNAL
OF PROSTHETIC
Fig. 1. Brushes for removing debris from dowel pin holes.
DENTISTRY
117