Prosthodontics 3: The Edentulous State

Comprehensive practice flashcards covering the biological, functional, and morphological aspects of the edentulous state and dentures.

According to the lecture, what does the face embody in terms of social interaction?

It embodies our social identities and is one of the major vehicles for interpersonal communication.

What is the consequence of facial deviations that depart from culturally acceptable attractiveness?

They are shown to be disadvantageous to the individual, especially when deviations are significant.

When treating edentulous patients, what is the dentist managing besides oral biomechanics?

Their individuality.

Success in treating edentulous patients demands technical expertise and what other quality?

Empathy with the patient’s fears and aspirations.

What are the four determinants listed as causes for edentulism?

Cultural, financial, attitudinal, and previous dental treatment.

What does the edentulous state represent regarding the masticatory system?

A loss of the integrity of the masticatory system.

What structure provides support to ensure teeth function properly?

The periodontium.

What is the periodontium's role in attaching teeth to the jawbone?

It provides a resilient suspensory apparatus resistant to functional forces.

What hard connective tissues comprise the periodontium?

Cementum and bone.

What soft connective tissues comprise the periodontium?

The periodontal ligament and the lamina propia of the gingiva.

The periodontium is attached to the dentin by which tissue?

Cementum.

The periodontium is attached to the jawbone by which structure?

The alveolar process.

How are forces exerted on a tooth transmitted to the supporting bone?

By the periodontal ligament and the lamina propia of the gingiva, which maintain continuity between the tooth and bone.

What are the two principal functions of the periodontium?

1. Support and 2. Positional Adjustment of the Tooth.

What is the secondary and dependent function of the periodontium?

Sensory Perception.

During which activities are the greatest forces acting on the teeth normally produced?

Mastication and deglutition.

What is the direction of the greatest forces normally acting on the teeth?

Essentially Vertical.

How are physiological occlusal forces characterized?

Intermittent, rhythmic, and dynamic in nature.

Which system controls the physiological occlusal forces on the teeth?

Neuromuscular mechanisms of the masticatory system.

Where are the receptors that regulate mandibular movements located?

In the muscles, tendons, joints, and periodontal structures.

Name the two types of vertical forces acting on the teeth.

1. Mastication 2. Deglutition.

Approximately how many times does deglutition occur per day?

$500\times/\text{day}$.

How does the duration of tooth contact during swallowing compare to chewing?

Contacts during swallowing are usually of longer duration.

What structures produce horizontal linguolabial/linguobuccal forces?

The tongue.

What structures produce horizontal labiolingual/buccobuccal forces?

The lips and cheeks.

During activity, which horizontal force typically exceeds buccolabial forces?

Lingual forces.

In a healthy dentition, when are the teeth in occlusion?

During deglutition, occasionally while masticating, and during clenching and grinding associated with parafunction.

Within a $24\text{-hour}$ period, how much total time are teeth subjected to functional forces?

Approximately $17.5\text{ minutes}$.

What is the approximate surface area of the periodontal ligament in each arch?

$45\text{cm}^2$.

What three properties allow natural dentition to cope with occlusal loading?

Viscoelastic properties, sophisticated sensory mechanisms, and the potential for bone remodeling.

What is the basic challenge in treating edentulous patients?

The differences between the ways natural teeth and their artificial replacements are supported.

What is the mean surface area of mucosa available for denture support in the edentulous maxilla?

$22.96\text{cm}^2$.

What is the mean surface area of mucosa available for denture support in the edentulous mandible?

$12.25\text{cm}^2$.

What happens to the denture-bearing area (basal seat) as residual ridges resorb?

It becomes progressively smaller.

In which directions does the maxillary arch resorb?

Buccally and labially.

In which directions does the mandibular arch resorb?

Labially and lingually.

What ridge relationship is created when the maxillary arch is confined within the mandibular arch in longstanding cases?

Pseudo-class III ridge relationship.

What is the typical masticatory force during occlusion in a natural dentition?

$200\text{ N}$.

What is the reported maximum masticatory force for complete dentures?

$60\text{ to }80\text{ N}$.

How do prosthesis patients frequently limit the loading of supporting tissues?

By selecting food that does not require masticatory effort exceeding their tissue tolerance.

What four components make up the Residual Ridge?

1. Mucosa, 2. Submucosa, 3. Periosteum, 4. Alveolar bone.

What is the eventual result of ongoing resorption of the alveolar ridge following tooth loss?

Gradual reduction and virtual disappearance.

What is Atwood's Classification Stage 3?

High well-rounded ridge.

What is Atwood's Classification Stage 4?

Knife-edge shaped ridge.

What is Atwood's Classification Stage 5?

Low well-rounded ridge.

What is Atwood's Classification Stage 6?

Depressed bone level.

What is the first stage in Atwood's Classification of Resorption?

Stage 1: preextraction.

During which time period is the rate of reduction in size of the residual ridge at its maximum?

The first $3\text{-}6\text{ months}$.

Why is an edentulous patient eventually described as a 'dental cripple'?

Because bone resorption activity continues throughout life, resulting in loss of varying amounts of jaw structure.

Which cells are responsible for bone deposition?

Osteoblasts.

Which cells are responsible for bone resorption?

Osteoclasts.

What percentage of bone mass is recycled weekly?

5\text{ -- }7\text{ %}.

How often is all spongy bone replaced?

Every $3\text{ -- }4\text{ years}$.

How often is all compact bone replaced?

Every $10\text{ years}$.

In which direction does the maxilla resorb in relation to the center?

Upward and inward (smaller).

In which direction does the mandible resorb in relation to the center?

Outward (becoming progressively wider).

What appearance is often attributed to the progressive change of the edentulous mandible and maxilla?

Prognathic.

Where does large proportion of bone loss occur in the anterior mandible?

Labial side.

Where does bone loss occur in the posterior (molar) region of the mandible?

Lingually.

Bone loss in the maxilla primarily occurs on which aspect?

Labial or buccal aspect.

What is the term for the resorption pattern in the maxilla?

Centripetal.

What is the term for the resorption pattern in the mandible?

Centrifugal.

In the first year after extraction, what is the reduction in residual ridge height for the maxilla?

$2\text{-}3\text{mm}$.

In the first year after extraction, what is the reduction in residual ridge height for the mandible?

$4\text{-}5\text{mm}$.

What is the annual rate of reduction in height for the mandible after the first year?

$0.1\text{ -- }0.2\text{ mm}$.

How much slower is the annual resorption rate of the maxilla compared to the mandible?

$4\text{ times}$ less.

A functional equilibrium of the masticatory system depends on the interaction of components, including the dentition and which system?

The neuromuscular system.

What are the two physical factors of denture retention that can be controlled by a dentist or technician?

1. Optimal Extension of the Denture Base and 2. Maximally initiate Contact of the Denture Base to its Basal Seat.

To minimize displacement, where should teeth be placed in relation to the musculature?

Within a zone defined by the functional balance (Neutral Zone).

How much weaker is the maximal bite force in denture wearers compared to dentate subjects?

$Five\text{ to }six\text{ times}$ less.

Which muscles play an important role in retaining and stabilizing complete dentures?

Orofacial and tongue muscles.

What is the 'neutral zone'?

A space in the edentulous mouth determined by the functional balance of the orofacial and lingual musculature.

List four functional differences between natural dentition and complete dentures.

1. mucosal vs. periodontal support, 2. movements during mastication, 3. migration of dentures/changes in relations, 4. different stimuli to sensory motor systems.

What five types of movements can complete dentures manifest?

Displacing, Lifting, Sliding, Tilting, and Rotating.

What are denture-bearing tissues constantly exposed to due to denture base movement?

Frictional contact.

What kind of habits involving repeated or sustained occlusal contacts can be harmful to the masticatory system?

Parafunctional habits.

What is the clinical term for tooth grinding?

Bruxism.

Bruxism involves an increase in the tonic activity of which muscles?

The jaw muscles.

What psychosocial factors may cause bruxism?

Stress, anxiety, or reaction to strong emotions (anger, frustration).

Name two medical conditions mentioned that may cause bruxism.

Oral tardive dyskinesia and Parkinson’s Disease.

A reduction in the vertical dimension of occlusion due to resorption leads to what facial outcome?

Decrease in total face height and resultant mandibular prognathism.

During maximal occlusal elements, what basic physiological relationships should be maintained by the dentist?

Relations between condyles, disk, and glenoid fossae.

Define 'Centric Relation'.

The most retruded relation of the mandible to the maxilla when condyles are in the most posterior unstrained position in the glenoid fossae.

What happens to the nasolabial groove in an edentulous state?

Deepening of the nasolabial groove.

What happens to the labiodental angle due to tooth loss?

Loss of labiodental angle.

What change occurs to the lip width in edentulous patients?

Narrowing of lips.

What happens to the horizontal labial angle in edentulous patients?

Decrease in horizontal labial angle.

Morphologic changes in the jaws depend on the balance of which two activities?

Osteoblastic and Osteoclastic Activity.

The success of complete dentures ultimately depends on what from the patient?

The patient accepting their need for prostheses and learning to use them.

Adaptation to dentures must take place in the context of which four patient states?

Oral, systemic, emotional, and psychological states.

What is the first step in successful management of an edentulous patient?

Identification of anticipated difficulties before treatment starts.

What must dentists train themselves to do regarding patient expectations?

Reassure the patient, perceive their wishes, and know how and when to limit their expectations.

The acceptance of a complete denture is accompanied by which process?

A process of habituation.

How is 'Habituation' defined in the lecture?

A gradual diminution of responses to continued or repeated stimuli.

What is the direction of bone resorption in the mandibular premolar region?

Buccal side.

Which classification system is used to describe residual ridge resorption?

Atwood's Classification.

What is Atwood's Classification for a postextraction ridge?

Stage 2.

What tissue covers the connective tissues of the periodontium?

Epithelium.

Is mandibular widening in the posterior region a result of maxilla or mandible resorption?

Mandible.

What specific angle increases in the edentulous state relating to the nose and lips?

Columella-philtral angle.