GV black classification, principles of amalgam

GV blacks classification was based on?

• location (anterior vs posterior)

• Origin (pit and fissure vs smooth surface)

• Extent (involving proximal surfaces or incisal edges)

which class did black not include?

VI: added in 1956 by simon

class I

• anterior and posterior:

  • pits and fissures (occlusal, buccal and lingual surfaces, including cingulum pits)

class I

class I

class II

Proximal surfaces of molars and premolars (posterior only)

• mesial or distal

class II

class II

class III

proximal surfaces of ANTERIOR teeth that do not involved incisal edges

class III

class III

class IV

proximal surfaces of anterior teeth that involve incisal edge

class IV

class IV

class V

Cervical (gingival) third of

• anterior

  • facial (or palatal)

• posterior

  • Buccal (lingual)

class VI

• incisal edges

  • ant teeth

• Occusal cusp tips

  • Posterior teeth

• no interproximal or pits and fissures

class IV vs Anterior class VI?

proximal surfaces involved in class IV

Definition of amalgam? dental amalgam?

any material that contains mercury as the main ingredient on its composition

• specific combo based on the mixture of silver-tin alloy with mercury is called dental amalgam

Dental Amalgam pros

• excellent strength

• Proven longevity (evidence based)

• Low cost

• self sealing

• not as technique sensitive

dental amalgam cons

esthetics, bonding to tooth structure?, mroe demanding cavity prep design when compared to composite

Threshold limit value of mercury

Amt of mercury vapor that can be allowed in air for workers who spend 8/day, 40 hrs a week in that enviroment

• OSHA 50 ug / m

• WHO: 25 u

• the worst dose a patient could from 10 or 12 amalgam restorations would be about 1/100 TLV

outline form of amalgam

• min depth

• Facolingual width

• remaining marginal ridge thickness

• internal line angles

• Buccal and lingual walls

• mesial and distal walls

• cavosurfarce angle

• acesss

• min depth: 1.5-2 mm or 0.2 mm into dentin (to avoid amalgam fracture)

• Facolingual width: 1/3 - ½ intercuspal width (1-1.5 mm)

• remaining marginal ridge thickness: greater or equal to 1.6 mm

• internal line angles: rounded

• Buccal and lingual walls: convergent occlusally

• mesial and distal walls: follow the orientation of enamel rods

• cavosurfarce angle: 90-100 degree exist

• acesss: parallel to long axis of tooth

outline form helpers

• #245:

  • length: 3 mm

  • width: 0.8 mm

  • convergent towards shank

  • rounded corners

• 330

  • shorter 1.6 mm

between cusp ridges, aim for …

1-1.5 mm (not less than 1)

the smallest amalgam condenser width?

1 mm

mesial and sital walls at > 1.6 mm

mesial and distal walls at 1.6 mm marginal rideg

convergent, 1.6 = divergent

cavosurface angle of amalgam

90-100 degrees: formed between an internal wall and non prepared surface of tooth

4 things resistance form is achieved by

1. Sufficient area of flat pulpal floor (peripheral seat)

2. conservation of healthy tooth

3. strong ideal enamel margins (no unsupported enamel)

4. sufficient depth (1.5 mm) for adequate thickness of restoration

retention form: prevents what?

• primary?

• secondary?

dislodgement of restoration

• retentive features: facial and lingual walls - converging occlusally

• secondary: pins and grooves (#1/4 round of 169 L)

convenience form

convenience form requires that the extent of prep be adjusted to provide adequate access and visability

Resistance form: no unsupported enamel:

• enamel rods?

• Rods: ?

• enamel margin?

• from DEJ to external surface of ename;

• converge toward center of developmental grooves

• Perpendicular to tooth surface