common faults in impression making 2016

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COMMON FAULTSIN IMPRESSION MAKING

Hpone Kyaw Myint

Department of Prosthodontics

University of Dental Medicine, Mandalay

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Outline of the Presentation

• Introduction

• Common faults in lower impression

• Common faults in upper impression

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Introduction

• Very first step for good and successful

removable dental prosthesis

• If objectives of primary impression are

failed…

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Common faults in lower impression

• Five faults

• Order in frequency of fault

• Reasons as well as correction methods are

described

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• Fault #. 1 insufficient depth in the posterior

lingual pouch

• Most occurring one

Common faults in lower impression

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Proper Impression

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Fault #. 1 may be caused by

1. Tray flang is too short

2. Shortage of impression composition

3. In adequate force

4. Tongue trapped

Common faults in lower impression

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Corrections for fault #. 1 are

1. Use long flange

2. Get sufficient impression composition

3. Use due force

4. Instruct the patient to raise the tongue

Common faults in lower impression

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• Fault #. 2 insufficient depth in the lingual,

labial and buccal sulci

• Second most occurring one

Common faults in lower impression

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Proper Impression

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Fault #. 2 may be caused by

1. Lack of impression material

2. Using low pressure to seat tray

3. Material is too cold and can’t flow

Common faults in lower impression

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Corrections for fault #. 2 are

1. Use sufficient compo

2. Use proper pressure

3. Manipulate material properly and adequately

Common faults in lower impression

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• Fault #. 3 the presence of smooth hollow in

the buccal distal periphery

• Sometime occurs

Common faults in lower impression

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Proper Impression

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Fault #. 3 may be caused by

• Trapping of cheek

Common faults in lower impression

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Corrections for fault #. 3 are

1. Functional exercise

2. Retraction of cheek during pressing the

tray

Common faults in lower impression

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• Fault #. 4 edge of the tray showing through

the impression

• Occasionally occur

Common faults in lower impression

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Proper Impression

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Fault #. 4 may be caused by1. Incorrect centering of tray

2. No sufficient back ward pressure on tray

3. Improper size of tray

4. Long flanges of the tray

Common faults in lower impression

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Corrections for fault #. 4 are

1. Centre tray before pressing

2. Sure to give back ward pressure

3. Choose tray judiciously

Common faults in lower impression

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Fault #. 5 an asymmetrical impression

• Rarely occur

Common faults in lower impression

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Proper Impression

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Fault #. 5 may be caused by

• Unbalance loading of material

• Ignorance of operator

Common faults in lower impression

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• Corrections for fault #. 5 are

1. Load material smartly

2. Care to seat loaded tray

Common faults in lower impression

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This is the end of the part I.

Part II will be continue on

March 25, 2016 at 1300 hour to 1400 hour.

Thank you for your kind attention!

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Common faults in upper impression

• Five faults

• Order in frequency of fault

• Reasons as well as correction methods are

described

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Fault #. 1 shortage of impression in one or

more regions of labial sulcus, esp around the

tuberosities or the labial sulcus

• Most commonly occur

Common faults in upper impression

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Proper Impression

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Fault #. 1 may be

caused by• Material shortage

• Failure to mold material

• fail;ure to pull upper lip

• Low pressure

• Cold material

Common faults in upper impression

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• Corrections for fault #. 1 are

1. Load material smartly

2. Care to seat loaded tray

Common faults in upper impression

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Fault #. 2 too much composition beyond the

posterior palatal border of the tray

• Frequently occur

Common faults in upper impression

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Proper Impression

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Fault #. 2 may be caused by

• Usage of undue force

• Retaining pressure for long time

• Loading too much composition in palatal area

Common faults in upper impression

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Corrections for fault #. 2

• Make sure of pressure

• Stop upward pressure on tray if app 1 cm

• Loading material properly

Common faults in upper impression

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Fault #. 3 exposed tray

• Occasionally occur

Common faults in upper impression

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Proper Impression

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Fault #. 3 may be caused by

• Poor tray selection

• Poor tray adaption

• Incorrect centring of tray

Common faults in upper impression

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Corrections for fault #. 3

• Good knowledge in tray selection

• Smartly prepared the tray

• Careful seating of tray

Common faults in upper impression

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Fault #. 4 many compo in labial sulcus

• Sometimes occur

Common faults in upper impression

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Proper Impression

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Fault #. 4 may be caused by

• Unrelated tray and ridge

• Too much material in front of the tray

Common faults in upper impression

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Corrections for fault #. 4

• Care in seating tray over the ridge

• Put only sufficient composition in front of

the tray

Common faults in upper impression

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Fault #. 5 void of material at the midline of

the palate

• Rarely occur

Common faults in upper impression

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Proper Impression

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Fault #. 5 may be

caused by

• Material shortage

• Low pressure

• Cold composition

• Trapped air

Common faults in upper impression

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Corrections for fault #. 5

• Use sufficient material

• Applied due force

• Use warm material

Common faults in upper impression

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Reference

• Fenn; Clinical Dental Prosthetic

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Thank you for your kind attention…