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Construction of an autopolymerized acrylic jacket crown by direct technic
160 • T H E JO U R N A L O F T H E A M E R IC A N D EN T A L A S S O C IA T IO N
procured for this study presented varying degrees of gingival inflammation which ranged from slightly inflamed gingivae to frank gingival hypertrophy. Every mouth which was examined exhibited poor oral hygiene; materia alba was present on all the teeth, and blood was readily expressed from the gingival tissues.
From the authors’ observations, the formation of green stain was always asso ciated with lax oral hygiene and gingival inflammation. Therefore, it is possible that the true etiology of this condition probably lies in the relationship of the bacteria-laden debris to the gingival hemorrhage.
Construction of an autopolymerized acrylic jacket crown by direct technic
Henry A . Collett * Brooklyn, and Edward B. M cG ra th , f East H artford, Conn.
The autopolymerizing acrylic resins in their present stage o f development are somewhat less than ideal for the con struction of dental restorations. However, if their shortcomings are taken into con sideration and compensated for, they may be useful in certain procedures. A satisfactory plastic resin jacket crown can be constructed by a direct technic using one of several acrylic filling materials. The advantage of such a crown lies pri marily in the fact that it can be com pleted in one sitting. It will resist break age because of its elastic qualities and if properly handled will produce an es thetic and relatively permanent restora tion. The unfavorable characteristic of comparative weakness of the material can be compensated for to some extent by incorporating Fiberglas in the restora tion.
In a comparatively short period of time (a year more or less), these mate rials have a tendency to turn yellow be cause of oxidation of the activator. I f a plastic tooth designed for use on a re movable denture is hollowed out and used as a veneer on the restoration, the undesirable quality of color instability is overcome. Polymerization shrinkage may be off set by using the nonpressure technic. A no. 00 or 000 sable brush is moistened with liquid and then is used to moisten and carry several granules of powder to the tooth.
The opinions or assertions contained in this article are the private ones o f the w riter and are not to be construed as official or reflecting the views o f the Navy Department or the naval service a t large. •Commander, Dental Corps, U. S. Navy, U. S. Naval Dental C lin ic, Brooklyn. fDental Corps, U. S. N aval Reserve.
CO LLETT— M cG R A T H . . . V O L U M E 50, F E B R U A R Y 1955 • 161
Construction of autopolymerized acrylic crown by direct tech nic. A : Crown hollowed out from lingual aspect. B: Filling material painted on Fiberglas thread wrapped around preparation. C : Resin painted on lingual surface of restora tion. D and E: Crown cemented in place
When this technic is followed, the shrinkage takes place a little at a time as the crown is laminated. The over-all shrinkage of the entire crown is con siderably reduced. Most of the shrinkage takes place from the outside of the crown; therefore, the final fit is accurate. There seems to be little danger to the life of the pulp. T ech n ic • The tooth is prepared in the
usual manner. In most instances it is ad visable to prepare a shoulder somewhat larger than might be used for similar types of crowns to allow for incorpora tion of the Fiberglas reinforcement. A stock plastic tooth somewhat larger in size than the finished restoration is selected so that it may be ground to the desired size and shape. After the selected plastic tooth has been ground to approximately the right size, it is hollowed out from the lingual aspect. It is desirable to leave the mesial and distal portions intact for better re tention and esthetics (illustration, A ). The preparation is then lubricated with a thin coat of petrolatum, and a thin veneer of autopolymerizing resin is painted on. Although this material has no adhesive properties, the shrinkage may make the resin difficult to remove for fi nal shaping and cementation if the prep aration is not lubricated. This veneer is then allowed to set for three to five min utes. A bead is painted on the mesial and distal incisal angles to help retain the Fiberglas thread reinforcement. After this veneer has set, a layer of Fiberglas thread is wrapped around it, and an other thin layer of filling material is
162 • T H E JO U R N A L O F T H E A M E R IC A N D EN T A L A S S O C IA T IO N
painted on to retain the Fiberglas per manently (illustration, B ). The stock tooth is then ground to fit the gingival and labial surfaces of the preparation. It is filled with autopolymerizing resin and is placed over the veneer containing the Fiberglas. The lingual surface of the crown is painted in and allowed to set for five minutes (illustration, C ). The entire crown is removed from the preparation and allowed to set for ten minutes. The excess is then trimmed off the shoulder area. The lingual aspect is shaped and adjusted to the occlusion. At this time the final shaping of the crown is done. The Fiberglas must be entirely covered as it cannot be polished. The shoulder of the crown is then painted with autopolymerizing acrylic resin, and the crown is placed on the lu bricated preparation under pressure. This step will compensate for any shrinkage that may have taken place around the shoulder area, thus insuring an accurate fit. After three to five minutes setting
time, the crown is again removed from the preparation, and any overhang is trimmed off. The crown is then polished and placed on the preparation. The gin gival margin is checked for overhang or discrepancies. The finished crown is removed from the preparation, any lubricant that might remain is cleaned off and the crown is cemented in place (illustration, D and E ). Summary • A satisfactory plastic jacket crown can be constructed by the direct method if the operator uses a technic designed to compensate for the unfavor able properties of the material.
In the technic described the weakness of the material is compensated for by the incorporation of Fiberglas thread. The color instability is taken care of by using a stock plastic tooth to cover the visible portion of the crown. This technic does not appear to be harmful to the pulp.
Science Budget • I n the cu rren t fiscal year, w h ic h ends Ju n e 30, 1955, the U . S. G o vern m en t is spending $2 b illio n on scientific research and developm ent, a decline of about $200 m illio n fro m the yea r before. C u ts in spending fo r n ew p la n t and fo r ap plied research and developm ent account fo r the decrease. T h e allo w ance fo r basic research this yea r is $131 m illio n , an increase o f $10 m illio n. T h ese are some high ligh ts o f the N a tio n a l Science F o u n d a tio n ’s th ird report
Federal Funds for Science. O f the 1955 to ta l $1.5 b illio n w ill be spent on physical sciences, $211 m illio n on life sciences and $37 m illio n o n social science, in c lu d in g $18 m illio n fo r collecting general-purpose statistics.
" Science and the C itizen S cien tific American 191:54 December 1954.
procured for this study presented varying degrees of gingival inflammation which ranged from slightly inflamed gingivae to frank gingival hypertrophy. Every mouth which was examined exhibited poor oral hygiene; materia alba was present on all the teeth, and blood was readily expressed from the gingival tissues.
From the authors’ observations, the formation of green stain was always asso ciated with lax oral hygiene and gingival inflammation. Therefore, it is possible that the true etiology of this condition probably lies in the relationship of the bacteria-laden debris to the gingival hemorrhage.
Construction of an autopolymerized acrylic jacket crown by direct technic
Henry A . Collett * Brooklyn, and Edward B. M cG ra th , f East H artford, Conn.
The autopolymerizing acrylic resins in their present stage o f development are somewhat less than ideal for the con struction of dental restorations. However, if their shortcomings are taken into con sideration and compensated for, they may be useful in certain procedures. A satisfactory plastic resin jacket crown can be constructed by a direct technic using one of several acrylic filling materials. The advantage of such a crown lies pri marily in the fact that it can be com pleted in one sitting. It will resist break age because of its elastic qualities and if properly handled will produce an es thetic and relatively permanent restora tion. The unfavorable characteristic of comparative weakness of the material can be compensated for to some extent by incorporating Fiberglas in the restora tion.
In a comparatively short period of time (a year more or less), these mate rials have a tendency to turn yellow be cause of oxidation of the activator. I f a plastic tooth designed for use on a re movable denture is hollowed out and used as a veneer on the restoration, the undesirable quality of color instability is overcome. Polymerization shrinkage may be off set by using the nonpressure technic. A no. 00 or 000 sable brush is moistened with liquid and then is used to moisten and carry several granules of powder to the tooth.
The opinions or assertions contained in this article are the private ones o f the w riter and are not to be construed as official or reflecting the views o f the Navy Department or the naval service a t large. •Commander, Dental Corps, U. S. Navy, U. S. Naval Dental C lin ic, Brooklyn. fDental Corps, U. S. N aval Reserve.
CO LLETT— M cG R A T H . . . V O L U M E 50, F E B R U A R Y 1955 • 161
Construction of autopolymerized acrylic crown by direct tech nic. A : Crown hollowed out from lingual aspect. B: Filling material painted on Fiberglas thread wrapped around preparation. C : Resin painted on lingual surface of restora tion. D and E: Crown cemented in place
When this technic is followed, the shrinkage takes place a little at a time as the crown is laminated. The over-all shrinkage of the entire crown is con siderably reduced. Most of the shrinkage takes place from the outside of the crown; therefore, the final fit is accurate. There seems to be little danger to the life of the pulp. T ech n ic • The tooth is prepared in the
usual manner. In most instances it is ad visable to prepare a shoulder somewhat larger than might be used for similar types of crowns to allow for incorpora tion of the Fiberglas reinforcement. A stock plastic tooth somewhat larger in size than the finished restoration is selected so that it may be ground to the desired size and shape. After the selected plastic tooth has been ground to approximately the right size, it is hollowed out from the lingual aspect. It is desirable to leave the mesial and distal portions intact for better re tention and esthetics (illustration, A ). The preparation is then lubricated with a thin coat of petrolatum, and a thin veneer of autopolymerizing resin is painted on. Although this material has no adhesive properties, the shrinkage may make the resin difficult to remove for fi nal shaping and cementation if the prep aration is not lubricated. This veneer is then allowed to set for three to five min utes. A bead is painted on the mesial and distal incisal angles to help retain the Fiberglas thread reinforcement. After this veneer has set, a layer of Fiberglas thread is wrapped around it, and an other thin layer of filling material is
162 • T H E JO U R N A L O F T H E A M E R IC A N D EN T A L A S S O C IA T IO N
painted on to retain the Fiberglas per manently (illustration, B ). The stock tooth is then ground to fit the gingival and labial surfaces of the preparation. It is filled with autopolymerizing resin and is placed over the veneer containing the Fiberglas. The lingual surface of the crown is painted in and allowed to set for five minutes (illustration, C ). The entire crown is removed from the preparation and allowed to set for ten minutes. The excess is then trimmed off the shoulder area. The lingual aspect is shaped and adjusted to the occlusion. At this time the final shaping of the crown is done. The Fiberglas must be entirely covered as it cannot be polished. The shoulder of the crown is then painted with autopolymerizing acrylic resin, and the crown is placed on the lu bricated preparation under pressure. This step will compensate for any shrinkage that may have taken place around the shoulder area, thus insuring an accurate fit. After three to five minutes setting
time, the crown is again removed from the preparation, and any overhang is trimmed off. The crown is then polished and placed on the preparation. The gin gival margin is checked for overhang or discrepancies. The finished crown is removed from the preparation, any lubricant that might remain is cleaned off and the crown is cemented in place (illustration, D and E ). Summary • A satisfactory plastic jacket crown can be constructed by the direct method if the operator uses a technic designed to compensate for the unfavor able properties of the material.
In the technic described the weakness of the material is compensated for by the incorporation of Fiberglas thread. The color instability is taken care of by using a stock plastic tooth to cover the visible portion of the crown. This technic does not appear to be harmful to the pulp.
Science Budget • I n the cu rren t fiscal year, w h ic h ends Ju n e 30, 1955, the U . S. G o vern m en t is spending $2 b illio n on scientific research and developm ent, a decline of about $200 m illio n fro m the yea r before. C u ts in spending fo r n ew p la n t and fo r ap plied research and developm ent account fo r the decrease. T h e allo w ance fo r basic research this yea r is $131 m illio n , an increase o f $10 m illio n. T h ese are some high ligh ts o f the N a tio n a l Science F o u n d a tio n ’s th ird report
Federal Funds for Science. O f the 1955 to ta l $1.5 b illio n w ill be spent on physical sciences, $211 m illio n on life sciences and $37 m illio n o n social science, in c lu d in g $18 m illio n fo r collecting general-purpose statistics.
" Science and the C itizen S cien tific American 191:54 December 1954.