The Failure of Directly Placed Restorations

Question 1

Why do we restore teeth

Answer 1

• to stop lesion progression and prevent its recurrences
• restore occlusion and function
• restore aesthetics
• maintain the physiological integrity of the teeth with the adjacent hard and soft tissues
• restore patient comfort and satisfaction

Question 2

Longevity of a restoration how long fo they last?

Answer 2

Success - ability for restoration to perform as expected
Durability? Success

Survival rate - measure of clinical performance
Length of a time a restoration survives

Failure - inability of restoration to meet desired outcome

Patient and clinical variabilities will affect the outcome of a restoration

Question 3

Amalgam

Answer 3

Median survival rate 15 yrs

Question 4

Causes of amalgam failure

Answer 4

• incorrect case selection
• cavity prep - inadequate retention
• poor matrix prep
• amalgam manipulation
• contamination
• failure to condense
• improper finishing and polishing
• post operative pain - inappropriate lining material
• micro leakage, ditching, creep !!! (Amalgam seals itself be fit and disadvantage)
• tarnish and corrosion
• faulty contacts

Question 5

Composite

Answer 5

• low survival rate due to
  polymerisation shrinkage / polymerisation stress
• newer materials median survival 8yrs
• annual failure rate 2%

Question 6

Some of the causes of composite failure

Answer 6

• incorrect case selection
• difficulty to obtain long term adhesion between the composite resin and the dentine, failure at the gingival margin is not uncommon
• failure to light cure composite in increments
• contamination of the material ; moisture control
• polymerisation shrinkage causing cares, fracture, sensitivity, marginal deficiency

Question 7

Glass ionomer

Answer 7

Median survival 30-42 months in permanent teeth

Makes a good lining/base

Not strong enough to withstand heavy occlusal forces

Annual failure as a restorative material 7%

Question 8

Causes of glass ionomer restoration failure

Answer 8

Result of poor handling of material at the time of placement or excessive occlusal loads

Question 9

Implications of restorative failure

Answer 9

Time
Cost
Material choice
Technique
Remaining tooth structure

Question 10

Factors affecting the success and failure of restorations

Answer 10

Patient factors

Operative factors

Material factors

Question 11

Patient factors

Answer 11

• caries risk - OH, diet, regular GDP attender
• heavy occlusal forces; bruxism
• tooth to be restored
• cavity size / location
• pulpal health
• periodontal heath
• allergies

Question 12

Allergies

Answer 12

• oral lichenoid reaction of oral mucosa against amalgam or gold alloys
• allergy to amalgam or gold alloys or sensitivity to HEMA in resin composites / fissure sealants

Question 13

Operative factors

Answer 13

The correct choice of restorative dental material for the situation

Cavity design, retention, removal of unsupported enamel and weakened cusps

The optimal handling of that material

The use of exemplary clinical techniques in placement and finishing

Question 14

Material factors

Answer 14

• compressive strength
• rigidity (modulus of elasticity)
• surface hardness and surface wear characteristics
• flexural strength

Question 15

Material factors - micro leakage

Answer 15

Thermal expansion
Adhesion property
Resistance to fatigue
Solubility
Ditching and creep

Question 16

Marginal degradation; ditching and creep

What are they a result of?

Answer 16

Ditching and creep are a result of slow deformation of amalgam places under constant load

(when the load is less than necessary to produce fracture, causing marginal breakdown)

Mostly seen where using amalgam with gamma 2 phase products

Question 17

What is ditching?

Answer 17

Ditching / crevicing is breakage of a thin edge creating an irregular V shape crevice

Question 18

What is creep?

Answer 18

Creep happens when the corrosive products leak and fill the gap between the tooth and the restoration

Amalgam is self sealing (creep corrosive product leaks and seals the margins, reducing micro leakage and secondary caries.

Creep happens under stress however which can result in the amalgam restoration failure

Question 19

Assessment of restoration

Answer 19

FDI evaluation criteria

Aesthetic properties
- surface lustre
- staining
- surface margins
- colour match and translucency
- anatomical form

Functional properties
- fracture and retention
- marginal adaptation
- wear
- proximal anatomical form
- patients view
- postoperative hypersensitivity and tooth vitality

Biology
- recurrence of caries, erosion, abfraction
- tooth integrity
- periodontal response
- adjacent mucosa
- oral and general health

Question 20

Ways in which restorations fail

Answer 20

Disease
- cares
- toothwear
- periodontal disease
- pulpal problems
- trauma

Technical failure
- fractured restoration / tooth
- marginal breakdown
- defective contours
- failure of retention

Question 21

Clinically, how do you detect restoration failure?

Answer 21

Patient symptoms - pain / aestehtic concerns / disclouration / fracture

Visual and tactile inspection - caries / marginal breakdown / lost or fractured restoration / open contacts / overhangs

Transillumination

Radio graphic examination - caries / apical and periodontal status / overhangs

Occlusal examination - occlusal contact against the opposing structure / loss of anatomy

Question 22

Reason for replacement - caries

Answer 22

Primary - at a new site on the tooth

Secondary / recurrent caries
- at the margin or under restoration
- caries left behind after initial restoration phase

Question 23

Treatment options: repair or replace?

Answer 23

Repair the restoration is there is..

• no obvious spreading / gross caries that would structurally undermine the restoration or remaining tooth structure
• sufficient volumes of retained restoration remaining and it is strong enough to resist masticatory forces
• the possibility to bond or mechanically interlock the new restoration into the old restoration and tooth
• no potential aesthetic mismatches between the new and old material