An instrument dentures Norton
P. Smith,
for removal
D.D.S.,
of defective
crowns
or fixed partial
M.A.*
West Virginia University, School of Dentistry, Morgantown, W.Va. Removal of a failed clinical crown is a common procedure. This article describes an instrument that allows easy removal of defective crowns with access to all parts of the mouth. The instrument is inexpensive and can be obtained locally for modification by the dentist. MODIFICATION
OF INSTRUMENT
A flat-bladed, 90-degree offset screwdriver is obtained from a hardware store. This instrument has blades at each end of a handle with the shank placed at 90 degrees to the handle. The blade portions of the instrument are oriented at 90 degrees to each other, thus allowing engagement of a slot in any orientation from a tool location arc of 90 degrees. This is ideal for dentistry because that is the maximum range available in the average patient. Each end of the instrument is modified by grinding to provide a blade width of 1 by 4 m m tapered toward the shank. The ends of the instrument are smoothed with a round file and appropriate sandpaper disks. CROWN
REMOVAL
TECHNIQUE
A slot is cut in the buccal or lingual surface of the crown to be removed; the sides of the slot are kept parallel to each other. The slot should extend from the margin to halfway across the occlusal surface of the crown. The buccal surface *AssociateProfessor, Department of Prosthodontics. 1Q/4/226M3
2. Additional force can be gained by torquing frc3m occlusal surface.
Fig.
Fig. 1. After groove has been cut through crown to cement, slot is engaged with instrument and a torquing force is applied.
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
823
TIPS
Fi$, 8. of instrument allows access to either buccal or-1kgU.l surface of any tooth in mouth.
FROM
OUR
READERS
the crown flexes, gentle bcclusal pressure will result in removal of the crown. There are several advantages to the design of this instrument over those commonly used. W ith the blade at 90 degrees to the handle, easy accessto the buccal surface is possible for even the most posterior molar without excessive pressure on the patient’s lip. The blade, being parallel to the handle, allows accessto a lingual groove on maxillary or mandibular anterior teeth (Fig. 3). The lever arm is long enough and the instrument is sufficiently rigid to allow the use of the required force without instrument breakage and concurrent damage to the oral structures. The all metal construction of the instrument allows it to be sterilized. Should corrosion from autoclaving become a problem, the instrument can be made from a quarter-inch stainless steel rod by any machine shop. SUMMARY
w&h the instrument blade (Fig. 1). It he f&gem of one hand in contact with -control should the instrument slip the ether hand, a rotating force is apfrom tke slutt, plkdtotfie of the instrument, thus rotating the blade and widening the slot. The movement is reversed to apply force to the opposite side of the Blot. As the crown flexes, the movement can be felt with the fi~~gersofthe controlling hand. If the caeting does not separate after &veral tries, the slot is extended further across
An instrument has been described that provides the torquing forces needed to allow easy removal of defective crowns from all parts of the mouth. The instrument is inexpensive and can be obtained locally and modified by the dentist. Reprint requests to: DR. NORTON P. SMITH G-110 HEALTH SCIENCE NORTH SCHOOL OF DENTISTRY WJBT VIRGINIA UNIVERSITY MORGANT~WN, W V 26506
P. Smith,
for removal
D.D.S.,
of defective
crowns
or fixed partial
M.A.*
West Virginia University, School of Dentistry, Morgantown, W.Va. Removal of a failed clinical crown is a common procedure. This article describes an instrument that allows easy removal of defective crowns with access to all parts of the mouth. The instrument is inexpensive and can be obtained locally for modification by the dentist. MODIFICATION
OF INSTRUMENT
A flat-bladed, 90-degree offset screwdriver is obtained from a hardware store. This instrument has blades at each end of a handle with the shank placed at 90 degrees to the handle. The blade portions of the instrument are oriented at 90 degrees to each other, thus allowing engagement of a slot in any orientation from a tool location arc of 90 degrees. This is ideal for dentistry because that is the maximum range available in the average patient. Each end of the instrument is modified by grinding to provide a blade width of 1 by 4 m m tapered toward the shank. The ends of the instrument are smoothed with a round file and appropriate sandpaper disks. CROWN
REMOVAL
TECHNIQUE
A slot is cut in the buccal or lingual surface of the crown to be removed; the sides of the slot are kept parallel to each other. The slot should extend from the margin to halfway across the occlusal surface of the crown. The buccal surface *AssociateProfessor, Department of Prosthodontics. 1Q/4/226M3
2. Additional force can be gained by torquing frc3m occlusal surface.
Fig.
Fig. 1. After groove has been cut through crown to cement, slot is engaged with instrument and a torquing force is applied.
THE
JOURNAL
OF
PROSTHETIC
DENTISTRY
823
TIPS
Fi$, 8. of instrument allows access to either buccal or-1kgU.l surface of any tooth in mouth.
FROM
OUR
READERS
the crown flexes, gentle bcclusal pressure will result in removal of the crown. There are several advantages to the design of this instrument over those commonly used. W ith the blade at 90 degrees to the handle, easy accessto the buccal surface is possible for even the most posterior molar without excessive pressure on the patient’s lip. The blade, being parallel to the handle, allows accessto a lingual groove on maxillary or mandibular anterior teeth (Fig. 3). The lever arm is long enough and the instrument is sufficiently rigid to allow the use of the required force without instrument breakage and concurrent damage to the oral structures. The all metal construction of the instrument allows it to be sterilized. Should corrosion from autoclaving become a problem, the instrument can be made from a quarter-inch stainless steel rod by any machine shop. SUMMARY
w&h the instrument blade (Fig. 1). It he f&gem of one hand in contact with -control should the instrument slip the ether hand, a rotating force is apfrom tke slutt, plkdtotfie of the instrument, thus rotating the blade and widening the slot. The movement is reversed to apply force to the opposite side of the Blot. As the crown flexes, the movement can be felt with the fi~~gersofthe controlling hand. If the caeting does not separate after &veral tries, the slot is extended further across
An instrument has been described that provides the torquing forces needed to allow easy removal of defective crowns from all parts of the mouth. The instrument is inexpensive and can be obtained locally and modified by the dentist. Reprint requests to: DR. NORTON P. SMITH G-110 HEALTH SCIENCE NORTH SCHOOL OF DENTISTRY WJBT VIRGINIA UNIVERSITY MORGANT~WN, W V 26506
