TIPS
When adaptation is satisfactory, cure the VLC resin initially for 5 minutes by positioning a hand-held light source on the buccal flanges with the prosthesis in occlusion. After careful intraoral curing through the lingual flanges, remove the overdenture and place it within a VLC curing unit for 10 minutes to insure complete polymerization. Examine the cured resin and adjust for voids, artifacts, or areas of potential tissue impingement. There are advantages of utilizing this technique compared with the conventional methods of abutment activation. Of clinical value is the ease of manipulation of this material without the constraints of a timed set and the absence of adverse soft tissue reactions to exposure to methyl methacrylate free monomer. Potential disadvantages include the cost of equipment and supplies and unproven long-term bond strength between the VLC material, prosthetic teeth, and denture base resins.4
An advantage
of the direct
PROCEDURE 1. Make impressions and diagnostic casts of the patient’s dentition. 2. Make a diagnostic wax-up of the teeth to be restored. (The lower left first and second premolars are used for illustrations in this article.)
1014/39135
712
London, England. Dentistry,
Birmingham
READERS
1. Ogle RE, Sorenson SE, Lewis EA. A new visible light-cured resin system applied to removable prosthodontics. J PROSTHET DENT 1986;56: 497-6.
2. Khan Z, van Fraunhofer JA, Razavi R. The staining characteristics, transverse strength, and microhardness of a visible light-cured denture base material. J PROSTHET DENT 1987;57:384-6. 3. Brewer AA, Morrow RM. Overdentures. 2nd ed. St Louis: CV Mosby, 1980:129,139-40. 4. Clancy JMS, Boyer DB. Comparative bond strength of light-cured, heat-cured, and autopolymerizing denture resins to denture teeth. J PROSTHET DENT 1989;61:457-62. Reprint requests to: DR. RUSSELL A. WICKS POSTGRADUATE PROSTHODONTICS DENTAL SCHOOL UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER 7703 FLOVD CURL DR. SAN ANTONIO, TX 78284-7890
post and core technique
Provisional restorations often have to remain in the mouth several months and must exhibit adequate strength, color stability,l abrasion resistance, and marginal fit. To fulfill these requirements they are best made by use of a more time-consuming indirect technique instead of being formed directly on the mouth.2 It is often necessary to make t&e cast posts and cores for endodontically treated teeth. Provisional restorations made to fit the teeth at the post preparation appointment have to be remade or relined after cementation of the post and core, possibly resulting in a poorer fit and certainly involving more clinical time. The procedure described in this article illustrates how this problem may be avoided when a direct acrylic resin pattern is made for the post and core and an indirect technique for making the provisional restorations is used.
in Restorative
OUR
REFERENCES
N. J. Capp, BDS, FDS, RCS (Edin), MS,a and K. Warren, BDS, FDS, RCS (Edin), London, England, and Birmingham Dental Hospital, Birmingham, England
aPrivate Practice, bSenior Registrar Hospital.
FROM
Dental
DRD,
RCS (Edin)b
3. Prepare the two teeth for porcelain fused-to-metal crowns (Fig. 1). The first premolar requires a post and core buildup. 4. Make an acrylic resin core (Duralay, Reliance Dental Mfg. Co., Worth, Ill.) on a parallel sided plastic burnout post (Para-Post System, Whaledent, New York, N. Y.) (Fig. 1). 5. Make a reversible hydocolloid impression of the mandibular arch, including both prepared teeth with the acrylic resin post and core in place. 6. Pour a cast with a mix of fast-setting impression plaster (Gypsogum Impression Plaster, Associated Dental Products, Swindon, England). 7. Make a stone cast of the diagnostic wax-up (step 2) and use this to form a matrix. 8. Make aprovisionalrestorationof polymethylmethacrylate resin (Meyerson crown and bridge acrylic, Meyerson Tooth Corp., Chicago Ill.). A. Paint tinfoil substitute over the plaster cast, including the dies of the preparations. B. Make a mix of the resin, following the manufacturer’s instructions. C. Fill the matrix with resin. D. Seat the matrix on the cast with two preparations, place it in a pressure pot, and cure it for five minutes. 9. Remove the direct pattern from the first premolar. 10. Trim, seat, and adjust the occlusion; finish and polish the provisional restoration. 11. Cement the provisional restoration after blocking out
OCTOBER
1992
VOLUME
68
NUMBER
4
TIP5
FROM
OUR
READERS
Fig. 1. Preparations for porcelain fused-to-metal restorations on mandibular left first and second premolars. Direct acrylic resin pattern for post and core in situ on first premolar. Fig. 2. One-piece provisional restoration cemented on first and second premolars. Fig. 3. Cast post and core fitted on first premolar. Provisional restorations will reseat with minimal adjustment.
the prepared post space in the first premolar with cotton wool (Fig. 2). 12. Sprue, invest, cast, and polish the direct post and core. 13. At the next appointment, remove the provisional restorations and cement the gold post and core (Fig. 3). ‘The provisional may be recemented normally after the post and core is cemented in place. The final impressions may be made immediately or at a subsequent appointment. The provisional restorations will again fit the mouth, requiring only minimal adjustment where the sprue was attached to cast the gold post and core.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
REFERENCES 1. Preston JD. A systematic approach to the control of esthetic form I. J PROSTHET DENT 1976;35:393-402. 2. Crispin BJ, Watson JF, and Caputo AA. The marginal accuracy of treatment restorations: a comparative analysis. J PROSTHET DE :NT 1980;44:283-90.
Reprint requests to: MISS K. WARREN BIRMINGHAM DENTAL HOSPITAL ST. CHAD’S QUEENSWAY BIRMINGHAM, B4 6NN, ENGLAND
713
When adaptation is satisfactory, cure the VLC resin initially for 5 minutes by positioning a hand-held light source on the buccal flanges with the prosthesis in occlusion. After careful intraoral curing through the lingual flanges, remove the overdenture and place it within a VLC curing unit for 10 minutes to insure complete polymerization. Examine the cured resin and adjust for voids, artifacts, or areas of potential tissue impingement. There are advantages of utilizing this technique compared with the conventional methods of abutment activation. Of clinical value is the ease of manipulation of this material without the constraints of a timed set and the absence of adverse soft tissue reactions to exposure to methyl methacrylate free monomer. Potential disadvantages include the cost of equipment and supplies and unproven long-term bond strength between the VLC material, prosthetic teeth, and denture base resins.4
An advantage
of the direct
PROCEDURE 1. Make impressions and diagnostic casts of the patient’s dentition. 2. Make a diagnostic wax-up of the teeth to be restored. (The lower left first and second premolars are used for illustrations in this article.)
1014/39135
712
London, England. Dentistry,
Birmingham
READERS
1. Ogle RE, Sorenson SE, Lewis EA. A new visible light-cured resin system applied to removable prosthodontics. J PROSTHET DENT 1986;56: 497-6.
2. Khan Z, van Fraunhofer JA, Razavi R. The staining characteristics, transverse strength, and microhardness of a visible light-cured denture base material. J PROSTHET DENT 1987;57:384-6. 3. Brewer AA, Morrow RM. Overdentures. 2nd ed. St Louis: CV Mosby, 1980:129,139-40. 4. Clancy JMS, Boyer DB. Comparative bond strength of light-cured, heat-cured, and autopolymerizing denture resins to denture teeth. J PROSTHET DENT 1989;61:457-62. Reprint requests to: DR. RUSSELL A. WICKS POSTGRADUATE PROSTHODONTICS DENTAL SCHOOL UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER 7703 FLOVD CURL DR. SAN ANTONIO, TX 78284-7890
post and core technique
Provisional restorations often have to remain in the mouth several months and must exhibit adequate strength, color stability,l abrasion resistance, and marginal fit. To fulfill these requirements they are best made by use of a more time-consuming indirect technique instead of being formed directly on the mouth.2 It is often necessary to make t&e cast posts and cores for endodontically treated teeth. Provisional restorations made to fit the teeth at the post preparation appointment have to be remade or relined after cementation of the post and core, possibly resulting in a poorer fit and certainly involving more clinical time. The procedure described in this article illustrates how this problem may be avoided when a direct acrylic resin pattern is made for the post and core and an indirect technique for making the provisional restorations is used.
in Restorative
OUR
REFERENCES
N. J. Capp, BDS, FDS, RCS (Edin), MS,a and K. Warren, BDS, FDS, RCS (Edin), London, England, and Birmingham Dental Hospital, Birmingham, England
aPrivate Practice, bSenior Registrar Hospital.
FROM
Dental
DRD,
RCS (Edin)b
3. Prepare the two teeth for porcelain fused-to-metal crowns (Fig. 1). The first premolar requires a post and core buildup. 4. Make an acrylic resin core (Duralay, Reliance Dental Mfg. Co., Worth, Ill.) on a parallel sided plastic burnout post (Para-Post System, Whaledent, New York, N. Y.) (Fig. 1). 5. Make a reversible hydocolloid impression of the mandibular arch, including both prepared teeth with the acrylic resin post and core in place. 6. Pour a cast with a mix of fast-setting impression plaster (Gypsogum Impression Plaster, Associated Dental Products, Swindon, England). 7. Make a stone cast of the diagnostic wax-up (step 2) and use this to form a matrix. 8. Make aprovisionalrestorationof polymethylmethacrylate resin (Meyerson crown and bridge acrylic, Meyerson Tooth Corp., Chicago Ill.). A. Paint tinfoil substitute over the plaster cast, including the dies of the preparations. B. Make a mix of the resin, following the manufacturer’s instructions. C. Fill the matrix with resin. D. Seat the matrix on the cast with two preparations, place it in a pressure pot, and cure it for five minutes. 9. Remove the direct pattern from the first premolar. 10. Trim, seat, and adjust the occlusion; finish and polish the provisional restoration. 11. Cement the provisional restoration after blocking out
OCTOBER
1992
VOLUME
68
NUMBER
4
TIP5
FROM
OUR
READERS
Fig. 1. Preparations for porcelain fused-to-metal restorations on mandibular left first and second premolars. Direct acrylic resin pattern for post and core in situ on first premolar. Fig. 2. One-piece provisional restoration cemented on first and second premolars. Fig. 3. Cast post and core fitted on first premolar. Provisional restorations will reseat with minimal adjustment.
the prepared post space in the first premolar with cotton wool (Fig. 2). 12. Sprue, invest, cast, and polish the direct post and core. 13. At the next appointment, remove the provisional restorations and cement the gold post and core (Fig. 3). ‘The provisional may be recemented normally after the post and core is cemented in place. The final impressions may be made immediately or at a subsequent appointment. The provisional restorations will again fit the mouth, requiring only minimal adjustment where the sprue was attached to cast the gold post and core.
THE
JOURNAL
OF PROSTHETIC
DENTISTRY
REFERENCES 1. Preston JD. A systematic approach to the control of esthetic form I. J PROSTHET DENT 1976;35:393-402. 2. Crispin BJ, Watson JF, and Caputo AA. The marginal accuracy of treatment restorations: a comparative analysis. J PROSTHET DE :NT 1980;44:283-90.
Reprint requests to: MISS K. WARREN BIRMINGHAM DENTAL HOSPITAL ST. CHAD’S QUEENSWAY BIRMINGHAM, B4 6NN, ENGLAND
713
