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Impression Technique for Impression Technique for complete denturescomplete dentures

Dr. M A Abdullah M.D.S.Dr. M A Abdullah M.D.S.Associate Professor of Prosthodontics,Associate Professor of Prosthodontics,College of Dentistry, King Saud University.College of Dentistry, King Saud University.Saudi Arabia. Saudi Arabia.

References.Heartwell C M , Rahn A O ,Text book of complete Dentures,5th ed., Williams & Wilkins Co. Philadelphia,1993.

Complete Denture impressionComplete Denture impression

Is a negative registration of the entire denture bearing, Is a negative registration of the entire denture bearing, stabilizing and border seal areas present stabilizing and border seal areas present

in the edentulous mouth in the edentulous mouth

Objectives of complete denture impressionObjectives of complete denture impression

Preservation of supporting tissuesPreservation of supporting tissuesRetentionRetentionStabilityStabilitySupportSupportEstheticsEsthetics

Impression Techniques Impression Techniques

CLOSE MOUTH OR PRESSURE IMPRESSION CLOSE MOUTH OR PRESSURE IMPRESSION TECHNIQUE:TECHNIQUE:Records impression in a condition that assumes Records impression in a condition that assumes under masticatory load.under masticatory load.

NON PRESSURE OR MUCOSTATIC IMPRESSION NON PRESSURE OR MUCOSTATIC IMPRESSION TECHNIQUE :TECHNIQUE :Records impression of the tissue in an anatomicalRecords impression of the tissue in an anatomicalform without pressure.form without pressure.

SELECTIVE COMPRESSION IMPRESSION TECHNIQUE :SELECTIVE COMPRESSION IMPRESSION TECHNIQUE :Records impression with more compression on the tissueRecords impression with more compression on the tissuein certain selected areas than on other areas.in certain selected areas than on other areas.

This technique believes that occlusal loading during This technique believes that occlusal loading during impression will record the tissues in a functional form as impression will record the tissues in a functional form as during swallowing and eatingduring swallowing and eating

Advocates of this technique believe that the peripheryAdvocates of this technique believe that the peripheryof dentures must be established during function of dentures must be established during function

Pressure or Close Mouth Impression Pressure or Close Mouth Impression TechniqueTechnique

Procedure:Procedure:

Construct custom trays with compound occlusion rims.Construct custom trays with compound occlusion rims.

Adjust occlusion rims for interocclusal distance and Adjust occlusion rims for interocclusal distance and uniform contact in centric and eccentric positions.uniform contact in centric and eccentric positions.

Load the impression material into both the custom trays Load the impression material into both the custom trays simultaneously.simultaneously.

Have the patient close the mouth with the custom trays Have the patient close the mouth with the custom trays in mouth and moves the jaw through functional in mouth and moves the jaw through functional movements to record the impression.movements to record the impression.


Disadvantages:Disadvantages:

The total time during 24 hours associated with directsThe total time during 24 hours associated with directsfunctional occlusal force application to periodontal tissuefunctional occlusal force application to periodontal tissueis 17.5 minutes .is 17.5 minutes .Thus dentures are in function for a short Thus dentures are in function for a short period of time each day.period of time each day.

Dentures will fit well during mastication ,and will lift up at Dentures will fit well during mastication ,and will lift up at rest due to tissue rebound. rest due to tissue rebound. This results in premature This results in premature contacts.contacts.

Due to constant pressure on the tissues, Due to constant pressure on the tissues, mucosalmucosaltissue reaction and resorption may result. tissue reaction and resorption may result.

Graf H. Dent Clin North.1969;13:659Graf H. Dent Clin North.1969;13:659--665665


Non Pressure or Mucostatic Impression Non Pressure or Mucostatic Impression TechniqueTechnique

Advocates of this technique believe that impression must be recorded in an anatomic form of the tissues (resting form).

Dentures constructed by mucostatic impression technique have shorter flanges.

Short flanges are used to prevent the dentures moving in lateral direction and NOT for border seal.

Metal bases which are dimensionally stable are used.

Dentures do not cover broad areasDentures do not cover broad areas

Inadequate supportInadequate support

Short flanges do not support the lips and cheeksShort flanges do not support the lips and cheeks

Non Pressure or Mucostatic Impression Non Pressure or Mucostatic Impression TechniqueTechnique

Disadvantages:

Selective Pressure Impression TechniqueSelective Pressure Impression Technique

Primary stress bearing areas are recorded under pressure

The secondary stress bearing areas are recorded with minimal pressure

Peripheral areas are recorded under compression to develop seal

The pressure can be selectively applied to the tissue by the custom trays for making final impression

It combines pressure and minimum pressure principles in It combines pressure and minimum pressure principles in making impression for maxilla and mandible:making impression for maxilla and mandible:

Anatomy of edentulous maxillaAnatomy of edentulous maxilla

Labial and buccal frenum and Labial and buccal frenum and sulcus sulcus

Pteregomandibular Pteregomandibular rapheraphe or or ligamentligament

Hamular notchHamular notch

Incisive papillaIncisive papilla

Fovia Fovia palatinuspalatinus

MidpalatineMidpalatine suturesuture

Ridge, cuspid eminence , malar Ridge, cuspid eminence , malar bonebone

Anatomy of edentulous maxillaAnatomy of edentulous maxillaPrimary stress bearing Primary stress bearing

area:area:Horizontal portion of had Horizontal portion of had palate palate (1)(1)

Secondary stress bearing Secondary stress bearing area:area:ridge crest ridge crest (2).(2).

Non stress bearing areaNon stress bearing arearidge slopes ridge slopes ( n/c )( n/c )

Anatomy of Edentulous MandibleAnatomy of Edentulous Mandible

Labial, buccal & lingual frenae Labial, buccal & lingual frenae

Labial , buccal and lingual sulcusLabial , buccal and lingual sulcus

Buccal shelfBuccal shelf

Masseter grooveMasseter groove

Retromolar padRetromolar pad

Anatomy of edentulous MandibleAnatomy of edentulous Mandible

Primary stress bearing area:Primary stress bearing area:buccal shelf & retromaolar buccal shelf & retromaolar pad pad (1)(1)Secondary stress bearing Secondary stress bearing areaareaResidual ridge & genial Residual ridge & genial tubercles tubercles (2)(2)Non stress bearing areaNon stress bearing areaLabial and lingual inclines Labial and lingual inclines (n/c)(n/c)

PreliminaryPreliminary Impression of Maxillary ArchImpression of Maxillary Arch

Select edentulous perforated stock metal tray 6 mm larger than the outside surface of the ridge

Examine the extension of tray flange at labial and buccal areas

Examine the posterior extension of the tray by dropping the handle down . It must cover the hamular notches and vibrating line

Preliminary Impression of Maxillary Preliminary Impression of Maxillary edentulous archedentulous arch

Load the tray with alginate impression materialPlace small amount of impression material in the rugea area of the hard palatePlace the tray in the mouth. Hold the impression tray in the middle ofthe palate until the material sets

Impression in modeling plastic Impression in modeling plastic impression compound materialimpression compound material

ConstructionConstruction of Maxillary Custom Trayof Maxillary Custom Tray

Draw the outline of wax spacer in Draw the outline of wax spacer in pencil on the diagnostic cast.pencil on the diagnostic cast.

Do not cover the post palatal seal Do not cover the post palatal seal area with wax spacer ( arrow).area with wax spacer ( arrow).

Provide tissue stops at the molar Provide tissue stops at the molar and incisal regions. and incisal regions.

Advantages of Not Covering the Post palatal Advantages of Not Covering the Post palatal Seal Area with Wax SpacerSeal Area with Wax Spacer

Completed custom tray will contact the Completed custom tray will contact the post palatal seal areapost palatal seal area

Additional stress can be placed at this Additional stress can be placed at this area during impression makingarea during impression making

Border moldingBorder molding

The shaping of the border areas of an impression tray by functional

or manual manipulation ofthe tissue adjacent to the borders to duplicate the contour and size

of the vestibule

The glossary of prosthodontic,term,7thed.1999The glossary of prosthodontic,term,7thed.1999

Adjusting Maxillary Custom Tray Adjusting Maxillary Custom Tray

Reduce the flanges of the tray Reduce the flanges of the tray 2 mm short from the sulcus2 mm short from the sulcus

Adjust labial frenal attachmentAdjust labial frenal attachment

Adjust buccal frenal attachmentAdjust buccal frenal attachment

Do not remove the wax spacer Do not remove the wax spacer until final impression is madeuntil final impression is made

Establishing Vibrating LineEstablishing Vibrating Line

Place Place ““TT”” on the crest ridge ,move posteriorly until it on the crest ridge ,move posteriorly until it dips into hamular notch. Join the hamular notches dips into hamular notch. Join the hamular notches with pencil across the fovia palatinae. Confirm the with pencil across the fovia palatinae. Confirm the vibrating line by asking the patient to say series of vibrating line by asking the patient to say series of

short short ‘‘AHAH’’ soundssounds. . The The junction between the junction between the movable and immovable movable and immovable

soft palatesoft palate through the through the foveae palatinae is called foveae palatinae is called

vibratingvibrating lineline

Posterior Border of Maxillary Custom TrayPosterior Border of Maxillary Custom Tray

The posterior border The posterior border of the custom tray must cover of the custom tray must cover

the hamular notches the hamular notches and extend approximately and extend approximately

2 mm posterior to 2 mm posterior to the vibrating line across the vibrating line across

the palate the palate

Border MoldingBorder Molding

After tempering in water bath at 70 F, border mold it

in the mouth

Soften the modeling plastic impression compound over the alcohol torch flame, and place it over the border of

the tray.

Border Molding Labial SulcusBorder Molding Labial Sulcus

In the region of labial sulcus, In the region of labial sulcus, the upper lip is the upper lip is elevated elevated

and and extended outextended out and then pulled and then pulled downward and inwarddownward and inward. .

ReRe--soften the compound and repeat this procedure soften the compound and repeat this procedure to establish proper border molding.to establish proper border molding.

Border Molding Buccal SulcusBorder Molding Buccal Sulcus

In the region of buccal frenum , the cheek is elevated In the region of buccal frenum , the cheek is elevated and then pulled outward ,downward and inward .and then pulled outward ,downward and inward .Move the cheek backward and forward to simulate Move the cheek backward and forward to simulate movement of buccal frenum as in function during eating movement of buccal frenum as in function during eating and smiling and smiling

Border Molding of Buccal Sulcus at Border Molding of Buccal Sulcus at TuberosityTuberosity

The posterior buccal flange at the tuberosity region is The posterior buccal flange at the tuberosity region is border molded when the cheek is extended outward, border molded when the cheek is extended outward, downwarddownward and inwardand inward

With the tray in place, have the patient open With the tray in place, have the patient open mouth widely and move the jaw laterally to mouth widely and move the jaw laterally to establish the width of the sulcusestablish the width of the sulcus

Border Molding the Post palatal Seal AreaBorder Molding the Post palatal Seal AreaPlace strip of softened compound at Place strip of softened compound at the posterior border of the custom tray the posterior border of the custom tray and seat it firmly in the mouthand seat it firmly in the mouth

Mark vibrating line and post palatal seal Mark vibrating line and post palatal seal area with indelible pencilarea with indelible pencil

Seat the tray again firmly in the mouth Seat the tray again firmly in the mouth for the indelible pencil mark to be for the indelible pencil mark to be transferred to the tray . Remove excess transferred to the tray . Remove excess of modeling compound .of modeling compound .

Relief for ImpressionRelief for ImpressionPlace holes in the palate of the custom tray with no. 6 Place holes in the palate of the custom tray with no. 6 round bur to provide escape ways for the final round bur to provide escape ways for the final impression materialimpression materialThe holes provide relief while making final impression at The holes provide relief while making final impression at mid palatine raphe and hard palatal regions mid palatine raphe and hard palatal regions

Practice Positioning Border Molded Tray in Practice Positioning Border Molded Tray in Mouth Before Making Final ImpressionMouth Before Making Final Impression

Place the tray in mouth with labial fremum in the labial Place the tray in mouth with labial fremum in the labial notch.notch.Place index fingers at first molar region and seat the tray Place index fingers at first molar region and seat the tray until the posterior border of the tray fits into hamular until the posterior border of the tray fits into hamular notches and across the palatenotches and across the palateHold the tray in position with fingers placed in the palatal Hold the tray in position with fingers placed in the palatal region region

Making Final ImpressionMaking Final ImpressionThe mixed impression material is The mixed impression material is placed on the tray with borders placed on the tray with borders covered covered Seat the tray in the mouth and border Seat the tray in the mouth and border mold in the posterior region first and mold in the posterior region first and then in the anterior region then in the anterior region

The mixed impression material is The mixed impression material is placed on the tray with borders placed on the tray with borders covered covered Seat the tray in the mouth and border Seat the tray in the mouth and border mold in the posterior region first and mold in the posterior region first and then in the anterior region then in the anterior region

Do not load the tray with excess of material



Final Rubber Base Impression with Outline Final Rubber Base Impression with Outline LandmarksLandmarks

1.labial frenum1.labial frenum2. Labial flange2. Labial flange3. Buccal frenum3. Buccal frenum4. Bucaal flange4. Bucaal flange5. Pteromandibular raphe5. Pteromandibular raphe6. Fovea palatinae6. Fovea palatinae7. Vibrating line7. Vibrating line

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Preliminary Mandibular ImpressionPreliminary Mandibular Impression

Select perforated lower metal Select perforated lower metal tray with 6 mm larger than the tray with 6 mm larger than the outside surface of labial and outside surface of labial and lingual ridgelingual ridge

Raise the handle and examine Raise the handle and examine extension of tray flange at extension of tray flange at labial, buccal ,lingual and labial, buccal ,lingual and retromolar pad It should cover retromolar pad It should cover all these areasall these areas

Adapt strip of utility wax on Adapt strip of utility wax on the borders of the metal traythe borders of the metal tray

Load the tray with mixed Load the tray with mixed alginate material. Place the alginate material. Place the tray in the mouth with the tray in the mouth with the tongue raised slightlytongue raised slightly

Preliminary Mandibular Impression with modeling plastic Preliminary Mandibular Impression with modeling plastic impression compoundimpression compound

Soften the modeling plastic impression compound in a water bath.

The mandibular impression.

soften the impression borders using alcohol torch , temper it in water bath.

Reintroduce it in the mouth and activate the tissues to refine the impression.

Construction of Mandibular Custom TrayConstruction of Mandibular Custom TrayDraw the outline for wax spacer in pencil onDraw the outline for wax spacer in pencil onthe diagnostic cast.the diagnostic cast.

Do not cover the buccal shelf areas with wax spacerDo not cover the buccal shelf areas with wax spacer..Make additional tissue stops at the anterior regions.Make additional tissue stops at the anterior regions.

AdvantagesAdvantages

Completed custom try will contact the buccal shelf areasAdditional stress can be placed at these areas during the finalimpression The part of the tray in contact with buccal shelf areas act as tissue stops

Adjusting Mandibular Custom Tray Adjusting Mandibular Custom Tray Reduce the flanges of custom tray Reduce the flanges of custom tray 2 mm short of the tissue reflection 2 mm short of the tissue reflection of the:of the:Labial, buccal and lingual sulcui Labial, buccal and lingual sulcui and frenal attachmentsand frenal attachments

Do not remove the wax spacer until final impression is madeDo not remove the wax spacer until final impression is made

Border Molding Mandibular Labial FlangeBorder Molding Mandibular Labial Flange

Start border molding beginning Start border molding beginning with labial flange (1) , buccal with labial flange (1) , buccal flanges (2) and finally lingual flanges (2) and finally lingual flanges (3)flanges (3)

In the region of labial sulcus , the In the region of labial sulcus , the lower lip is lifted outward, upward lower lip is lifted outward, upward and inwardand inward..

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Border Molding The Labial and Buccal Flange of Border Molding The Labial and Buccal Flange of Lower TrayLower Tray

Anatomical ConsiderationsAnatomical ConsiderationsThe mandibular labial frenum The mandibular labial frenum

contains a band of fibrous contains a band of fibrous connective tissue that is attached to connective tissue that is attached to orbicularis oris. Therefore , the labial orbicularis oris. Therefore , the labial frenum is active.frenum is active.

Border molding the Buccal flange of lower Border molding the Buccal flange of lower traytray

The buccal flange must not extend lateral to The buccal flange must not extend lateral to external oblique ridge external oblique ridge The disto buccal flange must record the The disto buccal flange must record the masseter groove and the superior border of masseter groove and the superior border of retromolar pad retromolar pad In the region of buccal frenum, the cheek In the region of buccal frenum, the cheek is lifted outward, upward inward, backward is lifted outward, upward inward, backward and forward to simulate the movement of and forward to simulate the movement of buccal frenumbuccal frenumRecord masseter groove by instructing the Record masseter groove by instructing the patient to exert closing force and the dentist patient to exert closing force and the dentist exerting a downward pressure on the trayexerting a downward pressure on the tray

Border Molding the Lingual FlangeBorder Molding the Lingual Flange

The lingual flange is border molded The lingual flange is border molded in 5 steps in 5 steps Step 1.The extension of anterior Step 1.The extension of anterior lingual flange of the tray is limited by lingual flange of the tray is limited by the lingual frenum and sublingual the lingual frenum and sublingual folds, and is 2mm short of the tissuesfolds, and is 2mm short of the tissuesStep 2. Place the softened modeling Step 2. Place the softened modeling compound on the border of the tray compound on the border of the tray extending between premylohyoid extending between premylohyoid fossa fossa

nstruct the patient to protrude the tongue to nstruct the patient to protrude the tongue to stablish the length of the sulcusstablish the length of the sulcus

Establish Length and Thickness the Lingual Establish Length and Thickness the Lingual FlangeFlange

Step 2. Instruct the patient to protrude the tongue to Step 2. Instruct the patient to protrude the tongue to establish the length of the sulcusestablish the length of the sulcusThe compound is reThe compound is re--softened and placed again in the softened and placed again in the mouth and the patient is instructed to push the tongue mouth and the patient is instructed to push the tongue forcefully against the palate to determine the thickness of forcefully against the palate to determine the thickness of the flange the flange

Border Molding the Lingual FlangeBorder Molding the Lingual Flange

A. The lingual flange is extended A. The lingual flange is extended to the most superior level of the to the most superior level of the floor of the mouthfloor of the mouth

B. Slight pressure on mucosa B. Slight pressure on mucosa overlying lingual slope ensures a overlying lingual slope ensures a broader seal when tongue is at broader seal when tongue is at restrest

Border Molding of Lingual FlangeBorder Molding of Lingual Flange

Step 3. Modeling compound is added to the lingual borders from premylohyoid fossae posteri0rly on both sides .After placing the tray in the mouth, instruct the patient to protrude the tongue .This procedure establishes the length h of the sulcus

Step 4.Repeat step 3 and have the patient move the tongue laterally and touch the corners of the mouth

Remove the wax spacer from the tray

Border Molding Lingual FlangeBorder Molding Lingual FlangeStep 5.Add modeling compound Step 5.Add modeling compound on the distal end of the lingual on the distal end of the lingual flange of the tray.flange of the tray.

Place the tray in the mouth and Place the tray in the mouth and have the patient protrude the have the patient protrude the tongue to activate the superior tongue to activate the superior constrictor of the pharynx constrictor of the pharynx muscles (1) that support the muscles (1) that support the retromylohyoid curtain and retromylohyoid curtain and pterygomandibular raphepterygomandibular raphe

Instruct the patient to forcefully Instruct the patient to forcefully close the mouth .The resulting close the mouth .The resulting contraction of the medial contraction of the medial pterygoid muscles (2) limits the pterygoid muscles (2) limits the retromylohyoid area.retromylohyoid area.

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Final Rubber Base Impression Final Rubber Base Impression

Place the tray with impression material in Place the tray with impression material in patients mouth. Manipulate lips and patients mouth. Manipulate lips and cheekscheeks

..Have the patient move the tongue and Have the patient move the tongue and keep it in protruded position till the keep it in protruded position till the impression sets. impression sets.

Defects in ImpressionDefects in Impression

In correct tray position in mouth resulting in under In correct tray position in mouth resulting in under extended impressionextended impressionPressurePressureVoidsVoids

Final Impression with Border Outline LandmarksFinal Impression with Border Outline Landmarks

A,labial frenum ; B ,labial flangeA,labial frenum ; B ,labial flangeC, buccal frenum ; D,buccal flangeC, buccal frenum ; D,buccal flangeE, masster groove; F, retromoalar E, masster groove; F, retromoalar padpadG,Ling.frenum ; H, Premylohyoid G,Ling.frenum ; H, Premylohyoid eminence.eminence.I,retromylohyoid eminence I,retromylohyoid eminence

AA

CCBB

DD

EEFF

GGHH

II

Step 1. With a sharp knife vertically score the cast Step 1. With a sharp knife vertically score the cast to a depth of 1.5 mm along the vibrating line.to a depth of 1.5 mm along the vibrating line.

Step 2. Score the anterior border of the posterior palatal Step 2. Score the anterior border of the posterior palatal seal area to depth of 1 mm.seal area to depth of 1 mm.

Step 3. From step 1 bevel the cast posteriorly Step 3. From step 1 bevel the cast posteriorly to step 1 to a depth of 1.5 mmto step 1 to a depth of 1.5 mm

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Scoring the master cast at the posterior palatal sealat the posterior palatal seal

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