This document discusses creep and marginal deterioration of dental amalgam. It defines creep as the time-dependent plastic strain of a material under static load. Creep can be caused by the continued setting expansion of amalgam, formation of corrosion products, mastication, or thermal expansion during eating hot foods. Higher copper amalgam has lower creep around 0.2% compared to 2.5% for conventional alloy. Marginal breakdown is the gradual fracture of the perimeter of a dental amalgam filling, leading to gaps between the amalgam and tooth. Techniques to prevent marginal breakdown include correct carving of excess amalgam and burnishing the margins before and after carving. Alloys with lower creep values below 1% generally experience less marginal breakdown than higher-cre

1. CREEPS AND
MARGINAL
DETERIORATION
A M A L G A M
Presented by Villanueva, Justin and Limonar, Shane

2. CREEP
CREEP
CREEP
it is defined as the time-
dependent plastic strain of a
material under static load or
constant stress.

3. CREEP
CREEP
CREEP
O t h e r F a c t o r s t h a t c a u s e s c r e e p s o f a m a l g a m
I t a r i s e s f r o m t h e c o n t i n u e d s e t t i n g e x p a n s i o n o f t h e
a m a l g a m , t h e f o r m a t i o n o f c o r r o s i o n p r o d u c t s ,
m a s t i c a t i o n , o r f r o m t h e t h e r m a l e x p a n s i o n o f t h e
a m a l g a m d u r i n g i n g e s t i o n o f h o t f o o d s .

4. CREEP
CREEP
CREEP

5. conventional alloy -low copper
amalgam 2.5%creep
High performance alloy -High
copper amalgam 0.2%creep
CREEP
CREEP
CREEP
According to ADA Specification
no. 1 Creep should be below 3%
Influence of
Microstructure on creeps

6. CREEP
CREEP
CREEP

7. Instrument has been built in a
solid aluminum block containing
two amalgam specimen test
stations where the temperature
of 37degrees celsius is prescisely
controlled with a digital
microprocessor controller and a
designated creep test, weight is
applied onto the specimens.
Determining
Creep
CREEP
CREEP
CREEP

8. CREEP
CREEP
CREEP
Clinical significance of creep :
Creep causes the
amalgam to flow
such that the
unsupported
amalgam protrudes
out from the margin
of the cavity
Those unsupported
edges are weak and
may further weaken
by corrosion
This causes ditch
around the margins
of amalgam
restoration

9. MARGINAL
MARGINAL
MARGINAL
DETERIORATION
DETERIORATION
DETERIORATION

10. Referred to as “Marginal breakdown”,
“ditching”, and “crevice formation”.
Regardless of the type of amalgam,
marginal fracture increases with
time
“Marginal breakdown”,
ditching crevice formation

11. IT IS THE GRADUAL
FRACTURE OF THE
PERIMETER OR
MARGIN OF A
DENTAL AMALGAM
FILLING, WHICH
LEADS TO THE
FORMATION OF
GAPS BETWEEN
THE AMALGAM
AND THE TOOTH.
D E N T M A T

12. Excess amalgam, left lying over the occlusal or
proximal surface should be carved correctly
The angle of the carvo-surface margin should be
greater than 70º and the cavity should be
designed to allow for this.
On completion of packing, burnish the margins
both before and after carving to improve
marginal adaptation.
CLINICAL TECHNIQUES TO PREVENT
MARGINAL BREAKDOWN

13. THE ABSENCE OF THE
CORROSION-
SUSCEPTIBLE PHASE
IN THE
MICROSTRUCTURE OF
HIGH-COPPER
AMALGAMS IS
ASSUMED TO BE
THE PRINCIPAL
FACTOR RESPONSIBLE
FOR THE SUPERIOR
RESISTANCE OF
THESE ALLOYS TO
MARGINAL
BREAKDOWN..
D E N T M A T

14. marginal breakdown with alloys having creep
values below 1%, restorations made from higher-
creep alloys generally experience greater
marginal breakdown than do restorations of
lower-creep
alloys.

15. THE PRECISE
MECHANISM OF
MARGINAL
BREAKDOWN AND
SPECIFIC
PROPERTIES ARE NOT
COMPLETELY
UNDERSTOOD.
HOWEVER, IT IS
ADVISABLE TO SELECT
ALLOYS THAT
INHERENTLY HAVE
LOW CREEP AND
POSSESS EXCELLENT
RESISTANCE TO
CORROSION.
D E N T M A T

16. https://pubmed.ncbi.nlm.nih.gov/3855901/
https://www.slideshare.net/achillies88/strength-and-creep-of-dental-
amalgam-3837449
https://youtu.be/o_n-v7HVrt4
REFERENCE:

17. thank you for
listening!