Operative dentistry fifth year second semester Faculty of oral and dental medicine Lama El Banna Lama1997bana@gmail.com

1. Operative Assignment 2
Prepared by:
Lama El Banna
Marof Hamouda
Haneen Al Galiz
Dalia Al Siksik
Ayah Tbasi
Safaa Abu Maqaseb
Bushrah Al Shaaer
Alaa Haboush
Supervisor:

2. Dr. Inas AlAlem
Clinical Technique for Class I Amalgam Restoration
Class I restorations restore defects on the occlusal surfaces of posterior teeth, the occlusal
thirds of the facial and lingual surfaces of molars, and the lingual surfaces of maxillary anterior
teeth.
Initial Clinical Procedures A preoperative assessment of the occlusal relationship of the involved
and adjacent teeth is necessary. After administration of local anesthetic, isolation of the
operating field with the rubber dam is recommended .
Rubber dam isolation is especially indicated when removing deep caries (judged to be <1 mm
from the pulp), during amalgam condensation, and for mercury hygiene. In addition, the dam
prevents moisture contamination of the amalgam mix during insertion.
Tooth Preparation for Class I Amalgam Restoration
Initial Tooth Preparation: is defined as establishing the outline form by extension of the
external walls to sound tooth structure while maintaining a specified, limited depth (usually just
inside the DEJ) and providing resistance and retention forms.
The ideal outline form for an amalgam restoration incorporates the following resistance
form principles that are basic to all amalgam tooth preparations of occlusal surfaces.
1- Extending around the cusps to conserve tooth structure and prevent the internal line angles
from approaching the pulp horns.
2- Extending the outline to include fissures, placing the margins on relatively smooth, sound
tooth structure.
3- Extending the outline form to include enamel undermined by the caries lesion.
4- Using enameloplasty on the terminal ends of shallow fissures to conserve tooth structure.
5- Establishing an optimal, conservative depth of the pulpal wall.
Class I occlusal tooth preparation is begun by entering the deepest or most carious pit with a
No.245 carbide bur at high speed with air-water spray. A punch cut is performed by orienting
the bur such that its long axis parallels the long axis of the tooth crown.
When the pits are equally defective, the distal pit should be entered as illustrated. Entering the
distal pit first provides increased visibility for the mesial extension. the bur should be positioned
such that its distal aspect is directly over the distal pit, minimizing extension into the marginal
ridge (see Fig. 10.28C). he bur should be rotating when it is applied to the tooth and should not
stop rotating until it is removed from the tooth .

3. On posterior teeth, the approximate depth of the DEJ is located at 1.5 to 2 mm from the occlusal
surface. As the bur enters the pit, an initial target depth of 1.5 mm should be established. his is
one half the length of the cutting portion of the No. 245 bur. he 1.5-mm pulpal depth is
measured at the central fissure.
The pulpal wall is established 0.1 to 0.2 mm into dentin.
Distal extension into the distal marginal ridge to include a fissure or caries occasionally requires
a slight tilting of the bur distally (≤10 degrees). his creates a slight occlusal divergence to the
distal wall to prevent undermining the marginal ridge of its dentin support.
For premolars, the distance from the margin of such an extension to the proximal surface
usually should not be less than ~1.6 mm . For molars, this minimal distance is ~2 mm.
Minimal distal (or mesial) extension often does not require changing the orientation of the bur’s
axis from being parallel to the long axis of the tooth crown.
While maintaining the burs orientation and depth, the preparation is extended distofacially or
distolingually to include any fissures that radiate from the pit consideration should be given to
changing to a bur of smaller diameter or to using enameloplasty. Both of these approaches
conserve the tooth structure and therefore minimize weakening of the tooth.
When the central fissure has minimal caries, one pass through the fissure at the prescribed
depth provides the desired minimal width to the isthmus. Ideally the width of the isthmus should
be just wider than the diameter of the bur. It is well established that a tooth preparation with a
narrow occlusal isthmus is less prone to fracture .
If the fissure extends onto the marginal ridge, which results in less than 1.6mm marginal ridge
after preparation, the long axis of the bur should be changed to establish a slight occlusal
divergence to the mesial/distal wall to avoid undermining the enamel in the marginal area.
The strongest and ideal enamel margin should be
composed of full-length enamel rods attached to sound
dentin, supported on the preparation side by shorter
rods that are also attached to sound dentin.
The pulpal floor is almost always in dentin, depending
on the enamel thickness.
The adequate form of amalgam cavity preparation
requires that the extent of the preparation be adjusted
to provide adequate access, visibility and complete
removal of caries.
The initial preparation should ensure that all the
caries lesion is removed from the DEJ. At this stage, the pulpal wall should remain at the initial
ideal depth, even if any restorative material or soft caries lesion remains in the pulpal wall.
Remaining caries and, (if present, old restorative material) is removed during the final tooth
preparation.
Enameloplasty is not indicated in areas of contact, in these cases when enameloplasty is
contraindicated and deep fissure is found 3 are available:
1. Make no further change in the outline form (strongly considered except
in patients at high risk for caries).
2. Extend through the marginal ridge when margins would be lingual to the contact.
3. Include the fissure in a conservative Class II tooth Preparation.

4. In extensive caries depth, RDB less than 1mm, put liner on the pulpal floor before continuing
the preparation, this helps in reducing more stresses on the pulp during cavity preparation.
In extensive caries width, caries involving cuspal inclines,
orientation of the bur is important to make occlusal conversion with
Cavosurface angle of 90-100 degrees, this gives a space for
supported amalgam restoration.
For amalgam, cavity preparation should extend to the DEJ, even
in smaller caries, and extend laterally to remove all enamel
undermined by the caries lesion and examining the lateral
extension of the lesion.
Primary resistance form is obtained by extending outline of
the preparation to include only undermined and defective tooth structure Retention form
1. Primary retention form,, occlusal convergence of the enamel wall
2. Secondary retention,, undercuts area left in Dentin
When extending the outline form, Enameloplasty should be used in any indicated case Capping
the cusp is indicated when the defect extends to more than one half the distance between the
primary groove and cusp tip, When the distance is two third, cusp reduction and coverage to
prevent fracture during function.
Final tooth preparation include,,
1 removal of remaining defective enamel and soft Dentin
2 pulp protection
3 finishing the external wall
4 debridement (cleaning) and inspecting the preparation Maximum preparation depth =2 mm
If the remnants are few and small, they may be removed with an appropriate carbide bur
Removal of remaining lesion is best achieved by using a discoid type spoon excavator or slowly
revolving round carbide bur without affecting resistance form Usually no secondary resistance
or retention form features are necessary class 1 amalgam restoration An occlusal cavosurface
bevel is contraindicated in tooth preparation for amalgam restoration It is important to provide an
approximate 90_100 degree cavosurface angle, Which result in 80_90 degree amalgam at the
margins, this feature provide strength for restoration and tooth and prevent the chipping of
amalgam (brittle material) under occlusal load
Types of preparation may be restored by amalgam
1 faucial pit of mandibular molar
2 lingual pit of the maxillary lateral incisors
3 occlusal pit of the mandibular first premolar
4 occlusal pit and fissure of maxillary first molar
5 occlusal pit and fissure of the mandibular second premolar
Restorative Technique for Class I Amalgam Preparation
Desensitizer Placement:
A dentin desensitizer is placed in the preparation according to manufacturer recommendations
before amalgam condensation.
Insertion and Carving of the Amalgam

5. The triturated amalgam is placed into an amalgam well. The outline of the tooth preparation
should be reviewed before inserting amalgam to establish a mental image that will later aid in
carving amalgam to the cavosurface margin.
Amalgam should be carefully condensed into the pulpal line angles .The preparation should be
overpacked 1 mm or more using heavy pressure.
This ensures that the cavosurface margins are completely covered with well-condensed
amalgam. Final condensation over cavosurface margins should be done perpendicular to the
external enamel surface adjacent to the margins. The overpacked amalgam should then be
precarve
Finishing and Polishing of the Amalgam
carving may begin immediately after, the Hollenback carver may be used, with care not to
overcarving the groove or fossa areas. All carving should be done with the edge of the blade
perpendicular to the margins as the instrument is moved parallel
to the margins. Part of the edge of the carving blade should rest on the unprepared tooth
surface adjacent to the preparation margin.
Using this surface as a guide helps prevent overcarving amalgam at the margins and produces
a continuity of surface contour across the preparation margins. During carving, thin amalgam
should be removed from areas of enameloplasty. Thin amalgam left in these areas may fracture
because of its low edge strength. Deep occlusal anatomy should not be carved into the
restoration because these may thin the amalgam at the margins and weaken the restoration.
Under Carving leaves thin portions of amalgam (subject to fracture) on the unprepared tooth
surface. he thin portion of amalgam extending beyond the margin is referred to as lash. he
mesial and distal fossae should be carved slightly deeper than the proximal marginal ridges
After carving is completed, the outline of the amalgam margin should reflect the contour and
location of the prepared cavosurface
margin, An amalgam restoration that is more than minimally overcarved (i.e., a sub- marginal
defect >0.2 mm) should be replaced.f the total carving time is short enough, the smoothness of
the carved surface may be improved by wiping with a small, damp ball of cotton held with the
cotton pliers. Alternatively, postcarve burnishing may beissure and distal pit on the occlusal
surface.
Tooth preparation of class l occlusal lingual and occlusofacial amalgam restoration :
1.tooth preparation should be no wider than necessary, mesiodistal width of the lingual
extension should not exceed 1mm.
2.tooth preparation should be more at the expense of the oblique ridge , rather than
cantering over the fissure.
3.Especially on smaller teeth , the occlusal portion may have a slight distal tilt to conserve
the dentin support of the distal ridge.
4.Margins should extend as little as possible onto the oblique ridge , distolingual cusp ,
and marginal ridge
5.To conserve distal marginal ridge , bur should cut mesial to the pit rather than distal5. To
conserve distal marginal ridge , bur should cut mesial to the pit rather than distal
Insertion and light curing of the composite.
The technique for insertion of class 2 posterior composite is best to restore the proximal box
portion of the preparation first .
●It is important to place and light cure the composite incrementally to maximize the curing
potential and to reduce the negative effects of polymerization shrinkage.
●The number of increments will depend on the size of the proximal box.
●The first increments should be placed along the gingival floor and should extend slightly
up the facial wall.
●The increment should be no more than 2 mm thick.
●A second increment is then placed against the lingual wall to restore about two thirds of
the box.
●The final increment is then placed to complete the proximal box and develop the
marginal ridge.

6. ●Increments should be light cured for as long as needed , depending on the shade and
opacity of the composite used and the power of the light curing unit.
●Composite resin placement may be made more difficult by the stiffness and stickiness of
some composite.
●Heating the composite prior to insertion may help overcome these problems.
●The increased temperature lowers the viscosity of the composite resin.
Finishing and polishing of the composite:
●The occlusal surface is shaped with round or oval, 12 bladed carbide finishing bur or
finishing diamond.
●Excess composite is removed at the proximal margins and embrasure with a flame
shaped , 12 bladed carbide finishing bur or finishing diamond and abrasive discs.
●Narrow finishing strip may be used to smooth the gingival proximal surface.
Done
Thank you