Overview of Complete Dentures, Edentulous Challenge, and Secondary/Final Impressions

When do we use complete denture pros?

• when all else has failed

• when system health and adaptability is declining

• to restore function (speech and chewing)

• to restore facial appearance

• maintain health

• (we want to keep as much as we can and replace what is needed)

what are the 3 principles of pros?

Support, Stability, and Retention

define: complete denture support

resistance to vertical movement of the denture base toward the ridge (/underlying tissues)

what are the 2 components of support

• initial support from bone and mucosa when bilateral simultaneous contact of opposing posterior teeth

• long term support - load the tissue areas most resistant to resorption

define: complete denture stability

resistance to horizontal or rotational movements

what are the 4 components of stability

• ridge height and conformation

• base adaptation

• occlusal harmony

• neuromuscular control

what are the factors of stability

• shape of the alveolar ridges

• size of the alveolar ridges/vestibular depth

• flange length and shape

• intimate fit of prothesis

define: complete denture retention

resistance to displacement of the denture base away from the ridge

what are the 7 components of retention

• adhesion - attraction between unlike molecules

• cohesion - force between molecules of same material

• interfacial surface tension - thin fluid (or saliva) film between 2 closely contacting objects (between gums and denture)

• intimate tissue contact - impression technique affects (need to have good reproduction of oral tissues)

• border seal - prevent ingress of air (need to seal denture)

• atmospheric pressure

• Neuromuscular control - (learned phenomenon/how to wear it) external contour of denture bases promote

what is the support found in the natural dentition

45 cm2 in each arch (includes teeth and periodontal ligament)

what is the support of the maxillary complete denture

23 cm2 (has ridge and palate support

what is the support of the mandibular complete denture

12 cm2 (only has ridge support)

what is the first way to minimize residual ridge resorption

remove the dentures for at least 8 hours a day

what is the second way to minimize residual ridge resorption

using proper impression techniques

what is the third way to minimize residual ridge resorption

no contact of anterior teeth in centric relation closure

what is the fourth way to minimize residual ridge resorption

ensure occlusal harmony (clinical remount and occlusal refinement)

what is the purpose of clinical remount

this technique and equilibration at delivery reduce occlusal discrepancies

the first denture problem

dentures move around in the mouth

second problem of dentures

dentures create pressure on supporting mucosa and bone

third denture problem

pressure from dentures cause bone resorption

fourth denture problem

bone resorption results in decreasing horizontal stability and decreasing retention that are possible to achieve with the dentures

fifth denture problem

retention of complete dentures requires saliva of good quality and quantity. However, many denture patients take meds that cause xerostomia

sixth denture problem

the technical quality of dentures in use is not very high. 60% of dentures in use have a least 1 major deficiency

seventh denture problem

denturism is legal in 6 states, dental lab techs petitioning for the right to do dentures directly

eighth denture problem

complete dentures are sometimes prescribed as an economic alternative to more costly fixed and restorative treatments. dentures are not better than natural teeth and they are a substitute for no teeth at all

ninth denture problem

the useful life of a set of complete dentures is 7 - 10 years (ridge will change over time and you need to ensure harmony)

Pt classification: Philosophical

Pt understands that dentures is for their benefit and lets you work on them

Pt Classification: exacting/critical

Pt is very specific, may look up to topic online, they think they know what they want, critical of you when you work with them

Pt classification: Hysterical

Pt is nervous all the time, very emotional (overly), can’t seem to adapt to the situation

Pt classification: indifferent

Pt is only there because a loved one wants them to be there, they really don’t care about getting dentures or not

what do we look for in an intraoral exam for dentures?

• mucosa

• basal seat

• arch form

• interarch space

in an intraoral exam, what are we specifically looking for when evaluating the mucosa

the color and contours of the gingiva

in an intraoral exam, what are we specifically looking for when evaluating the basal seat

this is the ridges and the palate. we want to see the height, contour, ridge parallelism, palatal vault shape

in an intraoral exam, what are we specifically looking for when evaluating the arch form

form of the ridge, we specifically are looking for if it is square, tapering, ovoid (might affect fit of complete denture)

in an intraoral exam, what are we specifically looking for when evaluating the interarch space

how much space/room do we have; how much room do we have for the denture teeth, but also for the pink covered base

border molding

allows the intraoral soft tissues to form the length, width and shape of custom tray borders prior to making the secondary impression

intaglio

the interior surface that is determined by the impression

cameo

the viewable portion of the denture that extends in the occlusal direction

interocclusal record

record between the two arches at the appropriate vertical dimension of the face where the bite should be

comorbidities that come with complete edentulism

• malnutrition and obesity

• increased COPD events

• increased pneumonia related hospitalizations

• increased risk of head/neck cancer

• decline in cognitive function

• predictor of cardiovascular disease mortality

• reduced, but nonreplaced dentition associated with increased risk of mortality

causes of denture movement

• resiliency of tissue

• instability of dentures

Almost all of the principles of complete denture fabrication have been formulated to _______ _______ of the dentures or to _________ ___ ______ transmitted to the supporting structures

decrease movement; minimize the forces

due to the few natural adaptive mechanisms left by the time a Pt gets to the edentulous state, the dentures will rest on tissue that…

will change progressively and irreversibly

What are the supports within the natural dentition

dentin, cementum, pdl, alveolar bone

Wolff’s law

living bone responds to functional stress by depositing bone in areas of stress

(remarkable adaptability of natural teeth/masticatory system)

edentulous patients have very little _______ to _________ ________ on alveolar bone

adaptation; functional stress

residual ridge resorption

there is a reduction of bone after the teeth have gone

Who said: “the mean reduction in anterior mandibular ridge is 4 times that of the maxillary ridge”?

Dr. Tallgren

what are the proper impression techniques

• record tissues at rest

• extend denture base to use maximum support area

• placement of pressure on those tissues best able to tolerate pressure

bone is not

a static tissue, it is constantly being remodeled and replaced

bone of the maxillary ridge

partly covered by a layer of cortical bone after teeth are extracted

bone of the mandibular ridge

crest remains spongy, trabeculated and not very resistant to resorption

bone of the buccal shelf (of mandible)

made up of compact bone and is the primary support area for dentures in the mandibular arch

snowshoe principle

decrease the pressure per unit area by extending the denture base to cover the maximum area within physiologic tolerance (support)

in relation to the snowshoe principle we hope to:

• have more saliva contact = ….

• proper peripheral extension = ….

• more contact adhesion (retention)

• good border seal (retention)

xerostomia

dryness presents much difficulty for denture wearers— discomfort, ulcerations, retention loss, chewing problems

medical conditions associated with xerostomia

• autoimmune and inflammatory conditions

• Graft-versus-host disease

• Immunoglobulin G4-related sclerosing disease

• degenerative disease (amyloidosis)

• granulomatous disease (sarcoidosis)

• infections: HIV/AIDS, hepatitis C

• Salivary gland aplasia or agenesis

medications often associated with xerostomia

• anticholinergic drugs

• antihistamines

• antihypertensive agents (angiotensin blockers/inhibitors, adrenergic blockers, diuretics)

• opioids

• psychotropic agents (antidepressants, antipsychotics)

• skeletal muscle relaxants

adhesion

attraction of unlike molecules for each other (mucosa-saliva-denture base)

the amount of retention attributable to adhesion is directly proportional to…

• wettability of denture base material

• area covered by the denture base

• viscosity of the saliva

Who said: “Our goal … not the meticulous replacement of that which is missing, but the preservation of that which remains”

Dr. M.M. Devan

The patient’s _________ and __________ with the dentist plays a substantial role in overall complete denture success (up to 50%)

personality; relationship

Who said: “Ideal impression must be in the mind of the dentist before it is in his hand. He must literally make the impression rather than take it.”

Dr. M.M. Devan

complete denture impression

a negative registration of the entire denture bearing, stabilizing and border seal areas present in the edentulous mouth

preliminary impression

an impression made for the purpose of diagnosis or for the construction of a tray

(good for records of mouth and occlusion)

what are the three impression philosophies

• minimal pressure

• functional pressure

• selective pressure

minimal pressure impression

attempt is made to exert as little pressure as possible during impression procedures. the objective is to capture tissues in their most undisturbed and undisplaced form

what is the rationale behind minimal pressure impression (aka the “mucostatic technique”)

suggested that if tissues are recorded in an undisturbed state using an accurate, free-flowing impression material, retention and stability of the dentures would be increased

who invented the mucostatic technique

Mr. Page, he was an engineer

in the minimal pressure impression, what material was used and how was it done

material: low viscosity, high flow (metal-oxide paste-ZOE, thin)

minimal pressure was used to seat the tray and to hold it

when do we still use the minimal pressure impression

when we find that the ridge is flabby and moveable (tissue) because the bones has resorbed

functional pressure impression

impression made with the soft tissue under a significant load (material used was more viscous)

how is a functional pressure impression done

the tray is seated and the patient closes the mouth with force while the material sets

what is the theory behind functional pressure impression

that the denture base-tissue contact during the function would be more intimate if tissue is recorded under compression

when is the functional pressure impression technique used today

when we need to add a new liner to a denture base, intaglio surface doesn’t fit very well

Selective pressure impression (what we use)

pressure is applied to certain areas based on dentist’s decision of where and how much. minimal pressure in certain areas, while more on other areas

in selective pressure impression, how do we control the pressure?

• wax spacer relief (between tray and ridge)

• drill vent holes in tray

• grind tray for relief space

• combo of all above

why use a custom tray

borders can be modified to control the movable soft tissues around the impression and avoid distorting them

what is the purpose of having space in custom trays

so that the shape of the tissues supporting the denture may be recorded with minimal or selective displacement in the primary support areas

in order to have a successful secondary impression, what is needed?

• mucosa should be healthy

• impression material of low viscosity

• use minimum pressure to seat tray

• seat and hold impression until set

purpose of border molding

to define denture border in length, width, shape, and contour. when it is completed, it should resemble anticipated denture border

definition of pre-extraction records

records and measurements obtained of the pt’s natural dentition prior to extraction of the teeth.

what is included in a pre-extraction record?

1. diagnostic casts

2. shade and dimensions from natural teeth

3. facial measurements (profile-assessment of lip position and contour; incisal plane; labio-lingual position of anterior teeth; OVD)

4. a record of the relationship of the incisal edges of the upper and the lower central incisors to the relaxed lips

5. Occlusal classification (I, II, III)

6. clinical photographs

7. A PVS impression of the labial surfaces of all the anterior teeth

What do pre-extraction records aid in?

1. determination of the incisal plane

2. establishing OVD

3. tooth selection and positioning

4. shade of teeth

5. lip position and fullness

6. re-establishment of natural intraoral relationships

what should we learn during a clinical exam

1. determine pt’s desires, demands, etc., by listenting and filling out the diagnostics survey

2. determine possible improvements in esthetics

3. determine the need for improved phonetics

4. observe and check: occlusion of denture (centric relation) and relationship of anterior teeth during speech (amount of vertical and horizontal overlap)

5. remove dentures and examine mouth

6. observe saliva

7. examine radiographs

8. examine previous dentures

What are the three components of the mucosa

masticatory, lining, specialized

masticatory mucosa

highly keratinized, best denture support (bound firmly to bone)

lining mucosa

thin, non-keratinized mucosa of lips and cheek. forms seal against denture, but does not resist stress (think about border molding)

specialized mucosa

dorsal surface of tongue. is keratinized, contains taste buds

the four characteristics for ideal denture bearing tissue

1. firmly bound, keratinized masticatory mucosa

2. a zone of connective tissue and submucosa

3. underlying cortical bone (really important)

4. muscle attachments nearby (enhance resistance to bone resorption)

centripetal resorption

routine resorption pattern following extraction of teeth results in a smaller maxilla when compared to dentate arch. this is a form of inward and upward resorption

ID

labial frenum

what are the characteristics of the labial frenum

• contains no muscle fibers

• inserts in vertical direction

• little lateral movement in function

  • notch in denture should be narrow and be accommodating

ID

labial vestibule

what is the labial vestibule

space between the labial frenum and buccal frenum. its reflection contains no muscle fibers

ID

buccal frenum

what is the buccal frenum

• either single or multiple

• ant-posterior direction of reflection

• may contain few fibers of caninus muscle

• notch in denture is broad since movement of the frenum is affected by buccinator and orbicularis oris muscle

ID

buccal vestibule

what is the buccal vestibule

• between buccal frenum and hamular notch

• space varies in size

• space must be filled vertically and laterally by denture flange to prevent ingress of air and loss of retention of max. denture

what is the other name for the buccal vestibule

retrozygomatic space (because it is the vestibular space posterior to the zygoma)