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The Proximal Gold Foil Filling Involving the Incisal Angle
THE PROXIMAL GOLD FOIL FILLING INVOLVING THE INCISAL ANGLE A. B . B u t t e r , D .D .S .; R. O . G r e e n , D.D .S., and W . J. S i m o n , D .D .S., Minneapolis, Minn. O those interested in gold foil, cav ities in the proximal surfaces of the incisor teeth which involve the incisal angle present interesting possibili ties. T h e chief objection to this type of filling from the patient’s point of view is the display of gold. W hile it is con ceded that the operation involving the incisal angle is necessarily extensive, it is possible, by judicious cutting, to develop the outline form so that the filling, when finished, will be far less conspicuous.
T
C A V I T Y P R E P A R A T IO N
Contrary to the teachings of some operators, the proximal labial margin should be a straight line from the incisal edge to a point beneath the free margin of the gingiva parallel to the long axis of the tooth, and as close to the em brasure as is consistent with the princi ples of extension to areas of relative immunity. (Fig. i, A .) If this cut is made otherwise, as, for instance, parallel with the proximal surface of the tooth, there will develop at the incisal angle an unsupported area o f enamel which will prove a menace in condensation, and the finished result will be out of harmony with the tooth. T h e amount of tooth structure cut from the incisal edge will depend on the type of tooth and the stresses placed upon the incisal angle. Ordinarily, the incisal cut is carried two-thirds of the way across the incisal edge (Fig. i, B ),
From the University of Minnesota, School of Dentistry, Department of Operative Den tistry. Jour. A .D .A ., Vol. 30, December 1, 1943
thus securing a greater leverage for the filling, w hich will be anchored by an incisal retention form. A cut which is not past the middle lobe of the tooth places the retention form in a position which may embarrass the pulp. B y crossing the incisal edge labiolingually, at an angle o f 45 °, additional re sistance to masticatory stresses from the lingual aspect is obtained. (Fig. 1, C.) This cutting can be done with a carbor undum stone. T h e proximal lingual wall can be cut down to a point below the free margin of the gingiva with a straight chisel. (Fig. 1, D .) T h e proximolinguoincisal angle is well rounded off, as indicated by the dotted line in Figure 1,D .
In cutting across the incisal edge, the stone is held in such a manner that the lingual enamel plate is reduced more than the labial plate. (Fig. 2, A .) Be cause of the stresses upon the tooth, the shape of the tooth and the thickness of the labial and lingual enamel plates, it is not possible to state dogmatically how m uch of the lingual plate should be removed. Generally speaking, it is" at least twice as much as the enamel re moved from the labial plate. O ne of the methods of reducing the lingual plates is to undermine the lingual enamel with a small single cut fissure bur. (Fig. 2, B.) W ith the chisel, as illustrated in Figure 2, C, the enamel 'is cleaved away, to effect the “ incisal step.” Some operators reduce the lingual enamel plate with small inverted cone stones, as shown in Figure 2, D. T h e “ incisal step” is to be
1853
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T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
finished smoothly with special burs, stones, chisels and cuttle disks when ac cessible. The proximal portion of the cavity should be extended far enough to free contact with the adjacent tooth. The gingival seat should either be flat (Fig. 3, A ) or should follow somewhat the curvature of the cervical line. An in verted cone bur is useful here provided care is taken that it is not brought too far labially or lingually. Primarily, the gingival seat must be so constructed that
A
B
pulp and the dentino-enamel junction. T he depth to which this bur is projected is a matter of judgment, depending on the size of the cavity and the stresses to be exerted on the filling. The bur is also drawn up the labioaxial and linguo-axial line angles approx imately a third of their length. These line angles are now emphasized and accentuated by the use of small monangle hoes. (Fig. 4, B.) Probably not more than a third of the linguo-axial line angle can be used for
C
D
Fig. 1.— A, proximoiabial m argin parallel to long axis of tooth. B, incisal cut carried approximately two-thirds of way across incisal edge. C, crossing incisal edge at an angle of 4 5 0 to obtain additional resistance to masticatory stresses from the lingual aspect. D , proximolinguo-incisal angle well rounded off.
A
B
C
Fig. 2.— A, initial reduction of lingual enamel plate. B, undermining of lingual enamel plate. C, cleaving away of undermined enamel. D , finishing “incisal step.”
it presents a flat surface at least at right angles to the line of incisal stress. Substantial retentive resistance form, which is necessary for this filling, is se cured by means of two point angles at the gingival portion and an incisal re tention form at the far end of the incisal step. T he gingival point angles are started with a small single-cut fissure bur. (Fig. 4, A .) The direction of the gingi val retention forms are such that they all times to be in dentin between the bisect the point angles. The bur is at
retentive resistance forms, but that por tion which is available must be utilized to the fullest extent. T h e labio-axial line angle, while it may be generally obtuse, should be pre pared in a definite manner. For example, Figure 5, A is a transverse section at the gingival seat, showing a retentive labioaxial and linguo-axial line angle which is definitely an acute angle. A t the junction of the gingival third and the middle third, the labio-axial and linguoaxial line angles approximate a right
B u t t e r , G r e e n a n d S im o n — G o l d F o i l
angle. (Fig. 5, B.) In the middle third (Fig. 5, G ), both line angles are obtuse and, in the incisal third (Fig. 5, D ) , the line angle fades out, leaving as much dentin as possible to support the enamel plates. T h e incisal step presents a flat ledge on the lingual aspect, which is all-important in the resistance of the filling to masticatory stress. T h e labial wall of
Fig. 3.— A, gingival seat. Th is should be flat. B, gingivo-axial line slightly acute, as is preferable.
Fig. 4.— A, gingival point angles started with small single cut fissure bur. B, line angles accentuated by means of monangle hoes.
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retention is made with a small single cut fissure bur slightly undercutting the mesial and distal walls as indicated by the letter X in Figure 3, B. This incisal retention form should be cut as large as is consistent with the area involved. G en erally, it is made too small for the pur pose for which it is intended. T h e incisal retention form should be directed gingivally parallel to the labio-incisal plate of enamel, keeping well within dentin and away from the lingual enamel plate. (Fig. 6.) T he cavosurface angles of the cavity should be planed and disked when ac cessible. T h e gingival cavosurface is beveled with a monangle hoe. Any other part of the cavity in which there is any doubt regarding unsupported enamel is also beveled. There should never be any
Fig. 6.— Incisal retention form directed gingivally parallel to labio-incisal plate of enamel. The completed cavity is presented in Figure 7, from various aspects in recapitula tion of some of the key points of the cavity preparation.
Fig. 5.— A, labio-axial and linguo-axial line angles, which are definitely acute angles. B, line angles approximating right angle. C, line angles obtuse. D, line angles fading out.
this step is cut parallel with the long axis of the tooth, a triangular portion of dentin remaining to support the labial plate. Retention is further secured by cutting a rectangular form at the far end of the incisal step. Usually, this
angles as such in the outline form to disturb the harmony of tooth outline form. c o n d e n s in g a n d fin is h in g
T o condense gold foil properly, the
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T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
force should be in as nearly a direct line as possible to the long axis of the tooth, so that the peridental membrane may resist the pressure demanded in filling. The plugger points should be cleansed frequently and the serrations freed of gold adhesions. T he amount of force applied in condensing gold foil will be governed not only by the surface area of the plugger points, but also by the tol erance of the patient. In the cavity preparation herein described, the ap proach is toward the incisal aspect.
is not done at this time, it will be diffi cult to go back and fill in the deficiencies later. When the filling has reached the “ incisal step,” the foil is started in the incisal retention form and condensed across the incisal to meet the proximal portion. (Fig. 8, C .) The incisal por tion and the proximal portion are welded together and, by maintaining condensa tion in line with the long axis of the tooth, the filling is built up to full con tour. (Fig. 8, D.) A fter burnishing the gold over the
A B C D Fig. 7.— A, proximolabial aspect of finished cavity, showing proximolabial m argin parallel to long axis of tooth and incisal cut carried approximately two-thirds of way across incisal edge. B, proximal aspect, illustrating “incisal step” and accentuation of labio-axial and linguoaxial angles from retention forms. C, proximolingual aspect. The proximolingual incisal angle is well rounded off. D, proximo-incisal aspect of finished cavity, showing incisal retention form and acute gingivo-axial line angle.
A B C D Fig. 8.— Steps in condensation of proximo-incisal gold foil filling.
Regardless of the type of plugger point, the gold foil is being wedged con tinually between the labio-axial wall and the linguo-axial wall. (Fig. 8, A .) T he foil should be stepped continually from the center of the mass of previously condensed gold foil toward one o f the walls. T h e gold foil is started in both of the gingival point angles, building up the axial wall at an angle of 450 (Fig. 8, B ), care being taken to carry the foil out to the full contour as we proceed. If this
margins, the surplus is trimmed off with knives, chisels, files, stones, disks and strips and the filling brought to shape and contour. In the final finishing of the proximo-incisal gold foil, it is essention not only to recover the original esthetic outline created, but to restore the harmonious proportions in the vary ing curves and angles of the tooth. v a r ia t io n s
There are other methods of treating cavities in the proximal surfaces o f in
B u t t e r , G r e e n a n d S im o n — G o l d F o il cisors in which the incisal angle has be come involved. Every operator wishes to display as little gold as is commensu rate with the stresses placed upon the filling. In cases of marked overjet, it is possible to prepare cavities which do not display any gold in the incisal edge. A cavity of this type is illustrated in Figure 9, A and B. In delicately shaped incisors with a short labiolingual diameter, the operator will experience difficulty in finding sufficient dentin between the labial and lingual plates of enamel for the incisal
Fig. 9.— A, labial aspect of mesial incisal cavity not involving labial plate at incisal edge. B, proximal aspect of same cavity.
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cavity which involves the incisal angle is to prepare the proximal portion in the orthodox manner, but, in place o f cutting down the incisal edge for re sistance, prepare a lingual dovetail for additional anchorage and resistance. (Fig. 11.) This cavity can be prepared only in teeth which have a marked labioversion. In teeth with a linguoversion, it is definitely contraindicated. This lingual dovetail should be placed as close to the incisal edge as is con sistent with the bulk of the tooth struc ture to prevent undue leverage from damaging the incisal angle.
Fig. 10.— Incisal retention form cut through lingual enamel plate and undercuts made in mesial and distal walls of “incisal” dovetail in dentin.
Fig. 11.— Four aspects of proximo-incisal foil cavity preparation, utilizing lingual dove tail for anchorage.
retention form. In this type of case, the incisal retention form is cut through the lingual enamel plate and undercuts are made in the mesial and distal wall of the incisal dovetail in dentin for reten tion. (Fig. 10.) In incisors w ith a short labiolingual diameter, the incisal retention form is cut through the lingual enamel plate and undercuts are made in the mesial and distal walls of the “incisal” dovetail in dentin for retention. (Fig. 10.) A n other method of treating a proximal
In short teeth that are thick labiolingually, it is occasionally possible to prepare a cavity involving the incisal angle without any special treatment other than establishing a bulky incisal retention form. (Fig. 12.) T h e involved incisal angle is slightly rounded to pro tect the enamel rods on the incisal edge. This preparation can be used only in those cases in which the lateral excursions of the opposing teeth do not place undue stress on the filling. W hile the preparation illustrated in
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T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
Figure 12 is considered in certain cases, it has been observed that gold foil under heavy stress has a tendency to pull away from the axial wall and to open at the incisal margin. In preparing a proximo-incisal cavity
the labio-axial line angle in upper in cisors. In the lower incisors, the incisal retention form is placed in dentin be tween the labial enamel plate and the lingual enamel plate. This requires dis cretion, since it is very easy to involve a pulp in a lower incisor. T h e cavity illustrated in Figure 13 is considered the normal cavity. It too is subject to variations depending on the form of the tooth in question and the relationship of the tooth to the adjacent and opposing teeth. su m m ary
Fig. 12.— Proximal gold foil cavity in volving incisal angle in which there has been no cutting of incisal edge or preparation of dovetail on lingual edge.
In the past, the masters of the gold foil art have shrouded the proximoincisal foil cavity preparation with a
Fig. 13.— Four aspects of proximo-incisal gold foil cavity for lower incisor.
for gold foil in the lower incisors, a con sideration of masticatory stress is impor tant. In cases of overbite, both normal and abnormal, it will be necessary to remove more of the labial enamel plate than the lingual enamel plate in lower incisors. (Fig. 13.) T h e anatomic form of a lower incisor is of such nature that frequently the linguo-axial wall need not be extended for the access desirable in an upper in cisor. Likewise, in lower incisors, it is the linguo-axial line angle that is ac centuated in much the same manner as
veil of complexity. In reality, the proximo-incisal foil cavity is less diffi cult to prepare than the strict proximal foil cavity, largely because it is readily accessible. A ll gold foil cavity prepara tion is based upon fundamental prin ciples, which m ay be varied in singular cases. T h e condensing of gold foil into a proximo-incisal cavity is exacting, re quiring skill which is acquired only by perseverance. Perfectly condensed, properly contoured gold foil fillings in a proximo-incisal cavity of harmonious proportions have no equal.
T
C A V I T Y P R E P A R A T IO N
Contrary to the teachings of some operators, the proximal labial margin should be a straight line from the incisal edge to a point beneath the free margin of the gingiva parallel to the long axis of the tooth, and as close to the em brasure as is consistent with the princi ples of extension to areas of relative immunity. (Fig. i, A .) If this cut is made otherwise, as, for instance, parallel with the proximal surface of the tooth, there will develop at the incisal angle an unsupported area o f enamel which will prove a menace in condensation, and the finished result will be out of harmony with the tooth. T h e amount of tooth structure cut from the incisal edge will depend on the type of tooth and the stresses placed upon the incisal angle. Ordinarily, the incisal cut is carried two-thirds of the way across the incisal edge (Fig. i, B ),
From the University of Minnesota, School of Dentistry, Department of Operative Den tistry. Jour. A .D .A ., Vol. 30, December 1, 1943
thus securing a greater leverage for the filling, w hich will be anchored by an incisal retention form. A cut which is not past the middle lobe of the tooth places the retention form in a position which may embarrass the pulp. B y crossing the incisal edge labiolingually, at an angle o f 45 °, additional re sistance to masticatory stresses from the lingual aspect is obtained. (Fig. 1, C.) This cutting can be done with a carbor undum stone. T h e proximal lingual wall can be cut down to a point below the free margin of the gingiva with a straight chisel. (Fig. 1, D .) T h e proximolinguoincisal angle is well rounded off, as indicated by the dotted line in Figure 1,D .
In cutting across the incisal edge, the stone is held in such a manner that the lingual enamel plate is reduced more than the labial plate. (Fig. 2, A .) Be cause of the stresses upon the tooth, the shape of the tooth and the thickness of the labial and lingual enamel plates, it is not possible to state dogmatically how m uch of the lingual plate should be removed. Generally speaking, it is" at least twice as much as the enamel re moved from the labial plate. O ne of the methods of reducing the lingual plates is to undermine the lingual enamel with a small single cut fissure bur. (Fig. 2, B.) W ith the chisel, as illustrated in Figure 2, C, the enamel 'is cleaved away, to effect the “ incisal step.” Some operators reduce the lingual enamel plate with small inverted cone stones, as shown in Figure 2, D. T h e “ incisal step” is to be
1853
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T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
finished smoothly with special burs, stones, chisels and cuttle disks when ac cessible. The proximal portion of the cavity should be extended far enough to free contact with the adjacent tooth. The gingival seat should either be flat (Fig. 3, A ) or should follow somewhat the curvature of the cervical line. An in verted cone bur is useful here provided care is taken that it is not brought too far labially or lingually. Primarily, the gingival seat must be so constructed that
A
B
pulp and the dentino-enamel junction. T he depth to which this bur is projected is a matter of judgment, depending on the size of the cavity and the stresses to be exerted on the filling. The bur is also drawn up the labioaxial and linguo-axial line angles approx imately a third of their length. These line angles are now emphasized and accentuated by the use of small monangle hoes. (Fig. 4, B.) Probably not more than a third of the linguo-axial line angle can be used for
C
D
Fig. 1.— A, proximoiabial m argin parallel to long axis of tooth. B, incisal cut carried approximately two-thirds of way across incisal edge. C, crossing incisal edge at an angle of 4 5 0 to obtain additional resistance to masticatory stresses from the lingual aspect. D , proximolinguo-incisal angle well rounded off.
A
B
C
Fig. 2.— A, initial reduction of lingual enamel plate. B, undermining of lingual enamel plate. C, cleaving away of undermined enamel. D , finishing “incisal step.”
it presents a flat surface at least at right angles to the line of incisal stress. Substantial retentive resistance form, which is necessary for this filling, is se cured by means of two point angles at the gingival portion and an incisal re tention form at the far end of the incisal step. T he gingival point angles are started with a small single-cut fissure bur. (Fig. 4, A .) The direction of the gingi val retention forms are such that they all times to be in dentin between the bisect the point angles. The bur is at
retentive resistance forms, but that por tion which is available must be utilized to the fullest extent. T h e labio-axial line angle, while it may be generally obtuse, should be pre pared in a definite manner. For example, Figure 5, A is a transverse section at the gingival seat, showing a retentive labioaxial and linguo-axial line angle which is definitely an acute angle. A t the junction of the gingival third and the middle third, the labio-axial and linguoaxial line angles approximate a right
B u t t e r , G r e e n a n d S im o n — G o l d F o i l
angle. (Fig. 5, B.) In the middle third (Fig. 5, G ), both line angles are obtuse and, in the incisal third (Fig. 5, D ) , the line angle fades out, leaving as much dentin as possible to support the enamel plates. T h e incisal step presents a flat ledge on the lingual aspect, which is all-important in the resistance of the filling to masticatory stress. T h e labial wall of
Fig. 3.— A, gingival seat. Th is should be flat. B, gingivo-axial line slightly acute, as is preferable.
Fig. 4.— A, gingival point angles started with small single cut fissure bur. B, line angles accentuated by means of monangle hoes.
18 55
retention is made with a small single cut fissure bur slightly undercutting the mesial and distal walls as indicated by the letter X in Figure 3, B. This incisal retention form should be cut as large as is consistent with the area involved. G en erally, it is made too small for the pur pose for which it is intended. T h e incisal retention form should be directed gingivally parallel to the labio-incisal plate of enamel, keeping well within dentin and away from the lingual enamel plate. (Fig. 6.) T he cavosurface angles of the cavity should be planed and disked when ac cessible. T h e gingival cavosurface is beveled with a monangle hoe. Any other part of the cavity in which there is any doubt regarding unsupported enamel is also beveled. There should never be any
Fig. 6.— Incisal retention form directed gingivally parallel to labio-incisal plate of enamel. The completed cavity is presented in Figure 7, from various aspects in recapitula tion of some of the key points of the cavity preparation.
Fig. 5.— A, labio-axial and linguo-axial line angles, which are definitely acute angles. B, line angles approximating right angle. C, line angles obtuse. D, line angles fading out.
this step is cut parallel with the long axis of the tooth, a triangular portion of dentin remaining to support the labial plate. Retention is further secured by cutting a rectangular form at the far end of the incisal step. Usually, this
angles as such in the outline form to disturb the harmony of tooth outline form. c o n d e n s in g a n d fin is h in g
T o condense gold foil properly, the
i 85 6
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
force should be in as nearly a direct line as possible to the long axis of the tooth, so that the peridental membrane may resist the pressure demanded in filling. The plugger points should be cleansed frequently and the serrations freed of gold adhesions. T he amount of force applied in condensing gold foil will be governed not only by the surface area of the plugger points, but also by the tol erance of the patient. In the cavity preparation herein described, the ap proach is toward the incisal aspect.
is not done at this time, it will be diffi cult to go back and fill in the deficiencies later. When the filling has reached the “ incisal step,” the foil is started in the incisal retention form and condensed across the incisal to meet the proximal portion. (Fig. 8, C .) The incisal por tion and the proximal portion are welded together and, by maintaining condensa tion in line with the long axis of the tooth, the filling is built up to full con tour. (Fig. 8, D.) A fter burnishing the gold over the
A B C D Fig. 7.— A, proximolabial aspect of finished cavity, showing proximolabial m argin parallel to long axis of tooth and incisal cut carried approximately two-thirds of way across incisal edge. B, proximal aspect, illustrating “incisal step” and accentuation of labio-axial and linguoaxial angles from retention forms. C, proximolingual aspect. The proximolingual incisal angle is well rounded off. D, proximo-incisal aspect of finished cavity, showing incisal retention form and acute gingivo-axial line angle.
A B C D Fig. 8.— Steps in condensation of proximo-incisal gold foil filling.
Regardless of the type of plugger point, the gold foil is being wedged con tinually between the labio-axial wall and the linguo-axial wall. (Fig. 8, A .) T he foil should be stepped continually from the center of the mass of previously condensed gold foil toward one o f the walls. T h e gold foil is started in both of the gingival point angles, building up the axial wall at an angle of 450 (Fig. 8, B ), care being taken to carry the foil out to the full contour as we proceed. If this
margins, the surplus is trimmed off with knives, chisels, files, stones, disks and strips and the filling brought to shape and contour. In the final finishing of the proximo-incisal gold foil, it is essention not only to recover the original esthetic outline created, but to restore the harmonious proportions in the vary ing curves and angles of the tooth. v a r ia t io n s
There are other methods of treating cavities in the proximal surfaces o f in
B u t t e r , G r e e n a n d S im o n — G o l d F o il cisors in which the incisal angle has be come involved. Every operator wishes to display as little gold as is commensu rate with the stresses placed upon the filling. In cases of marked overjet, it is possible to prepare cavities which do not display any gold in the incisal edge. A cavity of this type is illustrated in Figure 9, A and B. In delicately shaped incisors with a short labiolingual diameter, the operator will experience difficulty in finding sufficient dentin between the labial and lingual plates of enamel for the incisal
Fig. 9.— A, labial aspect of mesial incisal cavity not involving labial plate at incisal edge. B, proximal aspect of same cavity.
18 57
cavity which involves the incisal angle is to prepare the proximal portion in the orthodox manner, but, in place o f cutting down the incisal edge for re sistance, prepare a lingual dovetail for additional anchorage and resistance. (Fig. 11.) This cavity can be prepared only in teeth which have a marked labioversion. In teeth with a linguoversion, it is definitely contraindicated. This lingual dovetail should be placed as close to the incisal edge as is con sistent with the bulk of the tooth struc ture to prevent undue leverage from damaging the incisal angle.
Fig. 10.— Incisal retention form cut through lingual enamel plate and undercuts made in mesial and distal walls of “incisal” dovetail in dentin.
Fig. 11.— Four aspects of proximo-incisal foil cavity preparation, utilizing lingual dove tail for anchorage.
retention form. In this type of case, the incisal retention form is cut through the lingual enamel plate and undercuts are made in the mesial and distal wall of the incisal dovetail in dentin for reten tion. (Fig. 10.) In incisors w ith a short labiolingual diameter, the incisal retention form is cut through the lingual enamel plate and undercuts are made in the mesial and distal walls of the “incisal” dovetail in dentin for retention. (Fig. 10.) A n other method of treating a proximal
In short teeth that are thick labiolingually, it is occasionally possible to prepare a cavity involving the incisal angle without any special treatment other than establishing a bulky incisal retention form. (Fig. 12.) T h e involved incisal angle is slightly rounded to pro tect the enamel rods on the incisal edge. This preparation can be used only in those cases in which the lateral excursions of the opposing teeth do not place undue stress on the filling. W hile the preparation illustrated in
i858
T h e J o u r n a l o f t h e A m e r ic a n D e n t a l A s s o c ia t io n
Figure 12 is considered in certain cases, it has been observed that gold foil under heavy stress has a tendency to pull away from the axial wall and to open at the incisal margin. In preparing a proximo-incisal cavity
the labio-axial line angle in upper in cisors. In the lower incisors, the incisal retention form is placed in dentin be tween the labial enamel plate and the lingual enamel plate. This requires dis cretion, since it is very easy to involve a pulp in a lower incisor. T h e cavity illustrated in Figure 13 is considered the normal cavity. It too is subject to variations depending on the form of the tooth in question and the relationship of the tooth to the adjacent and opposing teeth. su m m ary
Fig. 12.— Proximal gold foil cavity in volving incisal angle in which there has been no cutting of incisal edge or preparation of dovetail on lingual edge.
In the past, the masters of the gold foil art have shrouded the proximoincisal foil cavity preparation with a
Fig. 13.— Four aspects of proximo-incisal gold foil cavity for lower incisor.
for gold foil in the lower incisors, a con sideration of masticatory stress is impor tant. In cases of overbite, both normal and abnormal, it will be necessary to remove more of the labial enamel plate than the lingual enamel plate in lower incisors. (Fig. 13.) T h e anatomic form of a lower incisor is of such nature that frequently the linguo-axial wall need not be extended for the access desirable in an upper in cisor. Likewise, in lower incisors, it is the linguo-axial line angle that is ac centuated in much the same manner as
veil of complexity. In reality, the proximo-incisal foil cavity is less diffi cult to prepare than the strict proximal foil cavity, largely because it is readily accessible. A ll gold foil cavity prepara tion is based upon fundamental prin ciples, which m ay be varied in singular cases. T h e condensing of gold foil into a proximo-incisal cavity is exacting, re quiring skill which is acquired only by perseverance. Perfectly condensed, properly contoured gold foil fillings in a proximo-incisal cavity of harmonious proportions have no equal.