Midterm - Amalgam Flashcards
(31 cards)
3 Reasons for Rubber Dam
Isolation - Moisture Control
Access - Retraction
Harm Prevention
Advantages to Rubber Dams
dry, clean operating field isolation max patient safety max operator safety improve restorative material properties optimize restorative outcomes
Disadvantages to Rubber Dams
time consumption
patient objection to use
not usable on all teeth (3rd, partial, malpositioned)
Forms of Isolation
cotton roll
svedopter
iso-dry
rubber dam
Materials for Rubber Dam Use
dam dam template frame floss scissors forceps punch retainer
Steps to Rubber Dam Use
determine operating field (1-2 teeth distal to opposite bi)
prepare the dam
select proper retainer (4 points need to contact tooth)
place the dam (invert ridges, ligatures)
remove rubber dam
Caries Classification
Class I - pit fissure Class II - posterior proximal Class III - anterior proximal Class IV - class III + incisal edges Class V - gingival 1/3 anterior and posterior Class VI - cups tips posteriors
Outline Form Defintion
shape of the area of the tooth surface included within the cavosurface margins of the cavity prep of a dental restoration
Resistance Form Definition
shape given to a prep that enables the restoration to withstand masticatory forces
Retention Form Definition
shape of a prep that prevents displacement of the restoration by lateral or tipping forces, as well as masticatory forces
Convenience Form Definition
changes needed outside the basic outline to enable proper instrumentation for cavity prep and insertion of the restoration
External Walls
buccal distal mesial lingual gingival (if one of the above is missing)
Internal Walls
axial
pulpal
Floor “seat”
pulpal
gingival
Resistance Form Principles
flat gingival/pulpal floor
conservative extension of the external walls
rounded internal line angles
covering weak cusps with restorative material
sufficient depth of preparation allowing for proper thickness of restorative material
bonding of restorative material to tooth
Retention Form Principles
Amalgam: buccal and lingual walls converge distal and mesial walls diverge dovetails retention grooves
Amalgam Preparation Principles
do not terminate on cusp tips
remove unsupported amalgam
preserve cuspal rige and marginal ridge (2mm molars, 1.6mm premolars)
preserve oblique ridge in max molars (1mm)
do nto extend to unaffected fissures
preserve cuspal inclines
smooth curves, no sharp edges
uniform pulpal depth (1.5mm 0.5mm from DEJ)
90 degree cavosurface margin
anatomy dictates occlusal outline form
Amalgam Restorative Principles
incremental placement multidirectional condensation overfill pre-carve burnish carve (form and function) adjust occlusion
Advantages Amalgam
ease of use
compressive strength and wear resistant
long term clinical success
lower cost
Disadvantages Amalgam
non-esthetic non-insulating weakens tooth technique sensitive more difficult prep initial marginal leakage
Isthmus Width Occlusal Amalgam
1mm, no more than 1/4 intercuspal width
Maxillary Class I Amalgam Preps
cut at the expense of the oblique ridge (cut DL cusp) leave 1mm sound enamel by oblique ridge OL - axial wall should be 1mm OL - axial wall should be convex OL - rounded axiopulpal line angle
Class II Amalgam
gingival floor width 1-1.5mm axially (0.5 mm from DEJ)
gingival “seat” follows external contour of the tooth
rounded axiopulpal line angle
proximal contact is visibly broken (tine of explorer, 0.5mm)
Class II Amalgam Materials
Tofflemire retainer
matrix bands
