The main reasons for failure of both amalgam and composite fillings according to several studies are secondary caries and fracture of the restoration. Amalgam fillings generally have higher longevity than composites, with survival rates over 10 years of 82-95% for amalgam versus 79-86% for composite according to two studies. However, factors like cavity size, surfaces involved, operator experience, and patient factors like oral hygiene and caries risk can significantly affect longevity. Annual failure rates are typically reported to be 0-7% for amalgam and 0-9% for composite in posterior teeth.

2. A direct restoration material composed of an alloy
consisting of mercury, silver, copper or tin.
Kolker et al estimated the average survival of
amalgam restorations is 22.5 years
Survival rate of 78% over a 5 year period

3. Advantages
Disadvantages
• Low technique sensitivity
• Lack of aesthetics
• High longevity & radiopacity
• Increased tooth removal
during tooth preparation
• High compressive strength
• Excellent wear resistance
• Ability to seal marginal spaces
over time
• Survival rates of between 5595% over a 5 year period

4. Technical work
of dentist
Marginal
ditching
Patient
behaviour
Cervical
overhangs
Secondary
caries
Tooth fracture
Not so much
the material
Main reasons
for failure of
AMALGAM

5. Figure 1
Figure 1: Demonstrates Corrosion of the Amalgam Restoration [2]

6. A direct restoration material composed of a monomer and polymer mix of
light curable resins.
Main reasons for failure were secondary caries and fracture of
restoration
Bernardo et al concluded the overall risk of failure due to secondary
caries was 3.5 times higher in composite than amalgam restorations
Survival rates of between 55-95% over a 5 year period

7. Advantages
Disadvantages
• Good aesthetics
• More technique sensitive
than amalgam
• Preservation of tooth
tissue during prep
• Low durability in posterior
teeth
• Low thermal
conductivity

8. Figure 2:
Figure 2: Large posterior composite demonstrates marginal discolouration
and wear [3].

9. Oral Hygiene
• Plaque adheres better to resin-based composites than
amalgam
Occlusal
Factors
• High occlusal function is associated with reduced longevity
• Amalgam has greater wear resistance than composites (useful
in heavy occlusion or para-function)
• However in normal occlusal function composites perform well
Preparation
Type
• Class I and II amalgam restorations have survival time between
25-70 years; not representative of the population, as it was on
highly motivated patients (dental students and staff)

10. Preparation
Size
• Failure rate increases for both materials as cavity size and
no. of walls involved increases, however this is more
pronounced in RBCs
• 14.2% of large amalgam restorations needed to be
replaced after 5 years as opposed to 19.8% of composite
restorations
Field Isolation
• Tooth must be isolated when using RBCs for effective
moisture control as moisture contamination compromises
the bond
• This is less critical for amalgam

11. ToothRestoration
Interface
PatientRelated
Factors
• Amalgam corrosion products fill the space between the
tooth and restoration … marginal seal improves with time
• Composite polymerisation shrinkage - compromises the
marginal seal and increases the risk of secondary caries
• Age, gender, reason for restoration
• Oral hygiene, caries risk, parafunctional habits
• Levels of cooperation and compliance

12. explain the failure of amalgam and
composite fillings

14. Norway Study [4]
Followed 27 dentists in Norway – looking at all of their class
II restorations (4030 in total), for over 4 years. Focus was on
adolescents
13 amalgams failed = 7.1% of the amalgams placed (lower
than composite failure rate)
407 RBCs (a larger number were placed) = 12.4%
Mean annual fail rate for:
Amalgam (1.6%) & resin composite (2.9%)

15. Norway Study [4]
For BOTH amalgam and
composite, the top reasons for
failure were:
Other failure reasons:
• 1. Secondary caries.
Composites were much more
susceptible: causing 73.9% of
the failures. Results may
have been affected by the
adolescent focused study –
their lifestyle increasing
secondary caries risk
• 2. Loss of the restoration
• Amalgams: due to tooth
fracture. Unlike amalgam composites crack before the
tooth
• Composites: due to marginal
defects and poor approximal
contact. Short term reasons:
un-contoured restorations and
porosities

16. Public Dental Health Service Study [5]
Observed the longevity of
resin composite ONLY
Included 2881 patients
with a mean age of 13.7
& 4355 restorations were
included by 115 dentists
Results showed:
84% survival rate at 8
years
Annual failure rate of 2%
Cavities were either class
I or II
We can compare this with
earlier reported annual
failure rates in
randomised long-term
longitudinal evaluations
between 0.5% and 3%

17. Restorations by dental students study
[6]


Measured longevity of 4009 restorations placed by dental
students
Summary:



Composite really is technique sensitive
In the short term, Class II resin composites are failing at a rate 10
times higher than with dental amalgam
Results:



6 amalgams (0.35% of amalgams) were replaced during 1 year
84 class II composites (3.6% of composites) were replaced during 1
year
21 composites of which were replaced in less than a month of

18. Restorations by dental students study
[6]
Reasons for
Restoration
Being
Placed by
Type of
Restoration
Reason for
Failure
Composite
Amalgam
Fracture
24
2
Missing
15
1
Void
15
1
Loose
7
Open Contact
7
Residual Caries
5
Failed/Defective
5
Sensitive/Painful
4
Open Margin
2
Total
84
2
6

19. Elliot, A. 2008 [7]
472 Portuguese
children, aged 8-12
years, with dental
caries in one or more
posterior teeth
Randomised to receive
either an:
- Amalgam or
- Composite
restoration
If restorations required
replacing = “failure”
Followed annually for
oral examination and
bitewings
Mean annual failure
rate
• 0.82% for amalgam
• 2.21% for composites

20. Comparing Long Term Survival
of Amalgam & Composite Restorations [2]
Bernado
et al.
Survival
Rates
- Secondary
caries
Risk was 3.5
times higher
in composites
vs. amalgam
Restorative
Material
Main reason
for failure for
both types:
Composite resin
85.5
Amalgam
94.4
0
20
40
60
80
100
Survival rate (%) over 7 years

21. Opdam et al.
Survival Rate
Findings: The
number of
surfaces restored
affects the
longevity
Summary of
Bernado &
Opdam studies:
After 7
years, both
materials have a
high longevity.
Years Post
Placement
Comparing Long Term Survival
of Amalgam & Composite Restorations [2]
82.2
79.2
10 yrs
91.7
89.6
5 yrs
0
20
40
60
Survival rate (%)
Composite
Amalgam
80
100

22. Patient factors influence on restoration failure [7]
32 GDPs were asked to record the reason for placement / replacement of 3196
restorations from a list of potential reasons
The restoration age, material & class were also recorded
Restorations placed:
54% amalgam, 32% composite, 8% compomer, 7% glass ionomer
Reasons for placement / replacement: 29% secondary caries, 28% primary
caries, 10% margin fracture, 7% tooth fracture, 6% non-carious defects
Mean age of restorations at failure = 7.1 years

23. How long do direct restorations last? [8]
Burke, F. and
Lucarotti, P.
(2008)
Data from 503,965
restoration
placements were
obtained from
80,000 adult
patients (46%
male, 54% female)
Summary: Single
surface
amalgams have
better survival
rates than class II
restorations
10 Year Survival of Amalgam Restorations

24. How long do direct restorations last? [8]
Burke, F.
and
Lucarotti, P.
(2008)
Summary:
Older patients
have
restorations
with a shorter
interval to reintervention
10 Year Survival of Restorations by Patient Age

25. Reasons for
resin
composite
replacement:
Percentage
Burke et al. 2001 [9]
100
90
80
70
60
50
40
30
20
10
0
Secondary Caries
Fractured
Restoration
Lost Restoration
Wear
Sensitivity
Resin
Composite
Amalgam
Pulpal Pain

26. Selection of dental materials &
longevity of replaced restorations in Sweden [10]
High caries risk patients  shorter longevity for resin based
composites vs. low / moderate risk patients due to recurrent
caries
Larger restorations  show greater failure rates
(class II = the most frequently replaced cavity)
Restorations replaced by more experienced dentists are shown
to have significantly longer longevity
Longevity of restorations depends on:
- Operator experience, patient caries risk, material
characteristics
Research suggests:
Composites longevity is 6 years & amalgams longevity is 16
years

27. A 24-month Evaluation of Amalgam and
Resin-Based Composite Restorations [11]
226 practitioners; 6,218 direct restorations.
• 386 restorations failed (6.2 %) during the following 23.7 months
Number of tooth surfaces restored helped predict subsequent restoration failure
… restorations with 4 or more restored surfaces were more than 4 times more
likely to fail
Restorative material and tooth type were not associated significantly with
longevity
Older patient age was associated highly with failure (P<0.001). Failure rate for
children was 4 percent, compared with 10 percent for people 65 years or older

28. Conclusion
Correctly performed
amalgam restorations in
posterior teeth have
higher longevity than
resin composites
These differences are
more pronounced when:
-The cavity is larger &
-There are multiple
surfaces involved [1]
Annual failure rates in
posterior stress-bearing
restorations are:
0% to 7% for amalgam
restorations
0% to 9% for direct
composites [12]

29. References






1. Soares AC, Cavalheiro A. A review of Amalgam and Composite Longevity of Posterior
Restorations. Rev Port Estomatol Med Dent Cir Maxilofac 2010;51:155-164
2. Is it the end of the road for dental amalgam? A critical review. J Conserv Dent. 2008
Jul-Sep; 11(3): 99–107.
3. Wilson NHF, Burke FJT, Mjo¨r IA. Reasons for placement and replacement of
restorations of direct restorative materials by a selected group of practitioners in the
United Kingdom. Quintessence International 1997;28:245–8.
4. Kopperud SE, Tveit AB, Gaarden T, Sandvik L, Espelid I. Longevity of posterior
dental restorations and reasons for failure. European Journal of Oral Sciences 2012;
120: 539–548.
5. Pallesen U, Van Dijken JWV, Halken J, Hallonsten AL, Ho¨igaard R. Longevity of
posterior resin composite restorations in permanent teeth in Public Dental Health
Service: A prospective 8 years follow up. Journal of dentistry 41 (2013) 297–306
6. Overton JD, Sullivan DJ. Early Failure of Class II Resin Composite Versus Class II
Amalgam Restorations Placed by Dental Students. Journal of Dental Education March
1, 2012 vol. 76 no. 3 338-340.

30. References






7. Elliot, A. (2008) The Risk of Failure is Higher for Composites than for
Amalgam Restoration. Journal of Evidence Based Dental Practice. Volume
8, Issue 2: Pages 83-84.
8. Burke, F. and Lucarotti, P. (2008) How long do direct restorations placed
within the general dental services in England and Wales survive? British Dental
Journal 206
9. Burke FJT, Wilson NHF, Cheung SW, Mjo¨r IA. Influence of patient factors
on age of restorations at failure and reasons for their placement and
replacement. Journal of Dentistry 2001;29:317–24.
10. Sunnegardh-Gronberg K, Van Dijken J, Funegard U et al. Selection of
dental materials and longevity of replaced restorations in Public Dental Health
clinics in northern Sweden. Journal of dentistry 2009; 37 (9), pp. 673--678.
11. McCracken MS, Gordan VV, Litaker MS et al. A 24-month evaluation of
amalgam and resin-based composite restorations. JADA 2013; 144, 583-593
12. Hickel R, Manhart J. Longevity of restorations in posterior teeth and
reasons for failure. J Adhes Dent 2001;3(1):45–64.