W5 - Functional (secondary) impression Flashcards
The aim of functional impression (4)
- Copying the displaced mucosa of the edentulous patient during movement
- Recording the range of movement
- Proper determination of the borders of complete denture
- Design of the valve closure
2 Tools for functional impression
- Functional tray
- Impression material
3 steps of Fabrication of functional tray
- The dental technican makes the primary cast according to the primary impression, that was taken by the dentist.
- The dentist outlines the borders of the special tray on the primary cast.
- The dental technician fabricates the special tray by the dentist requests.
Fabrication of functional tray
-> The dental technican makes the primary cast according to the primary impression, that was taken by the dentist.
-> What will the dentist do next?
The dentist outlines the borders of the special tray on the primary cast.
During Fabrication of functional tray, the last step is “The dental technician fabricates the special tray by the dentist requests”
-> What can the requests be?
- spaced/ close-fit
- extra-/intraoral handle
- perforated/ non-perforated
- material
Adjusting the special tray to a functional tray
-> What can the material be?
- thermoplastic impression materials („green Kerr”)
- Oroplastic impression material (ISO functional-”pink Kerr”)
- Silicone impression material in various consistency
How can we adjust the special trays?
- Tools and materials
- Staight handpiece and fraser
- Impression compound flame
- thermostatic water bath (~55oC)
How can we adjust the special trays?
- Tools and materials
- Staight handpiece and fraser
- Impression compound flame
- thermostatic water bath (~55oC)
Identify these 4 effects (based on arrows)?
Identify A, B, C
A) Attached gingiva
B) Movable mucosa
C) Moving/ mobile mucosa
Identify B & C
B) Movable mucosa
C) Moving/ mobile mucosa
Identify A, B, C
A) Attached gingiva
B) Movable mucosa
C) Moving/ mobile mucosa
Why do we have to pay attention to Upper labial frenulum and Buccal frenulum when adjusting the special tray?
Leave enogh space in the tray for the full range of their motion
Why do we have to pay attention to Pterygomandibular plica when adjusting the special tray?
- Runs from the maxillary tuberosity to the retromolar region
- While mouth opening it will tighten
- Serves as the lateral border of the posterior palatal seal
Why do we have to pay attention to Maxillary tuberosity when adjusting the special tray?
- not „tuber maxillae“
- Sholud be covered in all cases
- Has undercuts (exceptional retention!)
What is Coronomaxilary space?
The space between the lateral surface of the maxillary tuberosity and the buccal mucosa
Why do we have to pay attention to Coronomaxilary space when adjusting the special tray?
- Proper thickness→ outer suction effect
- Full covering the tuberosity→ engaging retentive undercuts
How can the shape of the coronomaxillary space be changed?
Moving the mandible side-o-side
What are the 2 techniques for taking functional impression?
- mucodynamic
- mucostatic
Materials used for functional impression
- zinc oxide-eugenol
- silicone
- oroplastic impression material
- polyether
- combined
What is MUCOSTATIC IMPRESSION? (a method for functional impression)
Mucostatic impression-taking is a functional impression-taking technique in which no force is applied to the impression spoon in the direction of the mucosa during the time the impression material is being applied, the spoon is simply held in place.
What is MUCODYNAMIC IMPRESSION? (a method for functional impression)
Mucodynamic impression-taking is a functional impression-taking technique in which a continuous and uniform force in the direction of the mucosa, approximately equal to the chewing force, is applied to the impression material at the appropriate location during the time of the impression material’s setting.
What are properties of Secondary ( master, functional) impression?
- Taken by a special tray,
- created onto the primary cast in the lab,
according to the outlineing of the dentist. - Made individually according to the tissues of the patient
- Working impression: the patient carries out special movements during
impression taking. - Extended till the border of the denture
What are Requirements of the denture base?
- Should be extended until its border lies on displaceable tissue where a seal can be obtained (sulcus, underextension)
- Mobile tissues adjacent to the border should not displace the denture or suffer injury (sulcus, overextension)
- Should have the closest possible contact with the surface of the mucous membrane lying beneath it (impression surface, precision)
- Extended, providing the possible maximum coverage of the jaw, ensuring that the minimum force per unit area is transmitted by the denture during function (clinical anatomy)
Transforming the special tray to functional tray
-> 5 properties
-control on the cast
-close fitting or spaced tray
-cleaning
-control in the mouth to have enough space for the chosen impression material 2-3mm.
-providing retention for the impression material
What is the disadvantage of Special tray adjustment modality which is under extension
It results an inaccurately fitting denture, because the unsupported impression material on the edges are distorted during casting
Adjustment of the special tray during special movements
-> How do we adjust during Opening and closing the mouth not maximally?
Both in the upper and in the lower jaw: Both in adjusting the special tray and making the impression
-> Moving: Posterior sulcus area
Adjustment of the special tray during special movements
-> How do we adjust during Opening and closing the mouth not maximally?
Both in the upper and in the lower jaw: Both in adjusting the special tray and making the impression
-> Moving: Posterior sulcus area
Adjustment of the special tray during special movements
-> Which areas are moving?
the upper and lower vestibular sulcus area
Adjustment of the special tray during special movements
-> How do we adjust the special tray during movement of the tongue according to the lower lip?
Adjusting the lower tray, and during lower secondary impression procedure:
Controlled regions:
- 1.sublingual area
- 2.paralingual area
-3.lingual pouch are controlled
Adjustment of the special tray during special movements
-> Why is blowing of the nose needed?
Adjusting the upper tray, taking the upper functional impression:
Controlled region:
-We control the vibrating line, the post dam region.
-The area between the 2 pterygomaxillar plica.
Adjustment of the special tray during special movements
-> What do we need to do when the patient is Swallowing?
Adjusting the lower special tray, taking the lower functional impression
Controlled region:
-Paralingual area, and lingual pouch
What is the disadvantage for mucostatic impression technique?
The distribution of occlusal loads by the finished denture will be uneven, the impression (intaglio) surface will be uneven.
=> Resulting injury during function—-foils. Physical retention is good in resting position.
What are Impression materials used for mucostatic impression technique?
Low and high viscosity impression materials are suitable. (gipsum, alginate, ZnO eugenol, silicon, poliéter-polisulfid, oroplastic.)
What are Indications for mucostatic impression technique?
-thin submucosa
-bad clinical-anatomical conditions
(great bone resorption)
Combinated impression technique with ZnO-eugenol and Oroplastic impression material
-> Steps of Upper secondary impression
1.static impression with ZnO eugenol paste.
2. borders are trimmed away and oroplastic material is placed 2mm width and height approximately
3. at mouth temperature functional movements are performed 3-4 times
4. cooled with water, eliminated from the mouth
Combinated impression technique with ZnO-eugenol and Oroplastic impression material
-> Steps of Lower secondary impression
- The edges of the secondary tray is covered with oroplastic material- functional movements are performed-cooled with water –eliminated from the mouth
- The whole surface of the tray is filled with ZnO paste, performed
Describe Special impression technique in case of flabby ridges
-fibrotic soft tissue
-not able to adapt to biting forces
-not adviceable to eliminate by oral surge
1.Mucocompressive impression taking with ZnO eugenol
2. Mucostatic part with ZnO eugenol, and strengthening with plaster of Paris
3. Control
Describe Special impression technique in case of Oronasal and oroantral communication
- trauma, tumor, malformation prae-and post op. stádium
- obtaining a vacuum effect is impossible.
- obturator or simple baseplate are possible.
Boxing with impression wax, casted with plaster of Paris
-> What should we do>
- The full depth and width of the sulci are carefully maintained
