180 Questions
What is the primary factor that determines the force of adhesion?
Surface area of the denture
What is the effect of a flat palate on retention and stability?
Increases retention and decreases stability
What is the ideal shape of the palatal vault for denture retention and stability?
U-shaped
What is the effect of thick ropy saliva on the cohesive force?
Decreases the cohesive force
What is the interfacial surface tension dependent on?
Size of the basal surface of the denture
Why is a perfect fit of the denture base essential?
To facilitate the interfacial surface tension
What is the reason behind the positive force holding the denture in place?
difference in pressure between the fitting and non-fitting surfaces
What is retention of a denture?
The quality that resists the force of gravity, adhesiveness of food, and forces associated with jaw opening
What is the consequence of border under extension in width and depth?
air enters under the denture, causing poor retention
What is adhesion in the context of denture retention?
The attraction of unlike molecules to each other
What type of arch form is considered the most favorable for denture retention?
square arch form
What is cohesion in the context of denture retention?
The attraction of like molecules for each other
What is the ideal form of the ridge for maximum support, retention, and stability?
high ridge with flat crest and parallel sides
What type of forces are resisted by the retentive force supplied by atmospheric pressure?
horizontal forces
What is one of the biomechanical factors that affects retention of denture?
Arch size
What is the term for the surface tension between the denture and the surrounding tissues?
Interfacial surface tension
What is the consequence of disharmony in jaw sizes in patients with class II and class III ridge relationships?
reduced retention
What is another term for atmospheric pressure as it relates to denture retention?
Gravity
Which arch form provides the most favorable prognosis for denture stability?
Square arch form
What is the function of the undercut area in denture retention?
To retain the side of the denture inserted first
What is the characteristic of a Class I soft palate?
A gentle curvature with little muscular movement
Which type of vault form is unfavorable for the retention of dentures?
Flat vault
What is the definition of stability in complete dentures?
The quality of the prosthesis to be firm, steady, and resist displacement by functional horizontal or rotational stresses
What type of mucosa provides the most favorable prognosis for denture stability?
Medium thickness mucosa with dense fibrous connective tissue
What is the effect of a flat ridge on denture stability?
It worsens denture stability
What is the ideal position of posterior teeth in relation to the mandibular ridge?
Lingual to the crest of the mandibular ridge
How does a small, narrow tongue affect denture stability?
It adversely affects stability
What is the result of placing posterior teeth on the upward incline of the mandible?
Increased denture movement
What is the effect of a large tongue on denture stability?
It enhances stability
What is the advantage of a shorter interarch distance?
Minimized undesirable leverage action and tongue forces
What is the primary function of adhesion in denture retention?
To create a physical attraction between unlike molecules
Which of the following physical factors affects retention of denture?
Interfacial surface tension
What is the effect of a large interarch distance on denture retention?
It decreases the retention of the denture
What is the role of cohesion in denture retention?
To create a physical attraction between like molecules
What is the effect of disharmony in jaw sizes on denture retention?
It decreases the retention of the denture
What is the purpose of a polished surface of the denture?
To reduce the friction between the denture and the mucosa
What is the characteristic of a Class I soft palate that makes it favorable for denture retention?
It has a gentle curvature and demonstrates little muscular movement
What type of ridge form is unfavorable for the retention of dentures?
Flat ridge form
What is the role of the undercut area in denture retention?
It retains the side of the denture inserted first
What is the effect of a flat vault on denture retention and stability?
It provides little resistance to lateral displacement
What type of arch form is considered the most favorable for denture stability?
Square arch form
What is the effect of a large tongue on denture stability?
It interferes with denture stability
What is the main reason why atmospheric pressure is effective in holding the denture in place?
There is an efficient seal around the denture border.
What is the primary function of the retentive force supplied by atmospheric pressure?
To resist horizontal dislodging forces.
What is the ideal shape of the ridge for maximum support, retention, and stability?
Square
What is the consequence of insufficient post dam in denture retention?
Decreased retention
What is the relationship between the arch size and retention?
Larger arch size increases retention.
What is the role of adhesion, cohesion, and interfacial surface tension in denture retention?
They resist vertical dislodging forces.
What is the ideal mucosa thickness for denture stability?
2-3 mm
What is the effect of a large tongue on denture stability?
Adversely affects denture stability
What is the ideal position of posterior teeth in relation to the crest of the mandibular ridge?
Buccolingually, lingual to the crest of the ridge
What enhances stability as the occlusal surfaces of teeth are closer to the ridge?
Decreased interarch distance
What is the effect of flabby tissue on denture stability?
Reduces denture stability
Why is a broad, thick tongue favorable for denture stability?
It enhances denture stability
What is the direction of the occlusal plane in relation to the denture foundation area?
Parallel
What is the effect of a high occlusal plane in relation to the residual ridge?
Decreased stability
What is the ideal shape of the polished surface of a denture?
Concave
What is the importance of proper relief of hard areas under the denture?
To prevent rocking and instability of the denture
What is the purpose of balanced occlusion in denture construction?
To ensure harmonious contact between upper and lower teeth
Which of the following areas requires relief under the denture?
Median palatine raphe
What is the main purpose of retention in a complete denture?
To resist the force of gravity
What type of attraction occurs between unlike molecules in denture retention?
Adhesion
Which of the following biomechanical factors affects denture retention?
All of the above
What is the result of the interfacial surface tension in denture retention?
Increased retention
What is the role of cohesion in denture retention?
Physical attraction between like molecules
What is the primary factor affecting the retention of a complete denture?
Physical factors
What is directly proportional to the size of the basal surface of the denture?
Interfacial Surface Tension
What is the impact of a flat palate on denture retention and stability?
Increases retention and decreases stability
What is the effect of thick ropy saliva on the denture?
Forces the denture out of its correct position
What is the relationship between surface area and adhesion?
Surface area is directly proportional to adhesion
What is the ideal shape of the palatal vault for denture retention and stability?
U-shaped
What is the effect of closeness of denture adaptation on adhesion?
Increases adhesion
What is the effect of a perfect seal around the border of the denture?
Increases retention
What is the ideal direction of the occlusal plane in relation to the denture foundation area?
Parallel to the residual ridge
Why is a high ridge with flat crest and parallel or nearly parallel sides favorable for denture retention?
It provides more support and retention
What shape of polished surface of denture tends to seat rather than unseat the denture?
Concave
What is the effect of air getting under the denture?
Decreases retention
What is the relationship between arch size and retention?
Larger arch size increases retention
What is the consequence of insufficient relief of hard areas under the denture?
Rocking and instability of the denture
What is the effect of a high occlusal plane in relation to the residual ridge?
Greater leverage action
What is the primary function of the retentive force supplied by atmospheric pressure?
Resists horizontal dislodging forces
What is the consequence of insufficient post dam in denture retention?
Decreases retention
What is the importance of balanced occlusion in denture stability?
It ensures harmonious contact between upper and lower teeth
What is the result of forces directed to an inclined plane?
More dislodging
What type of mucosa offers the most favorable prognosis for denture stability?
Mucosa of even, medium thickness
What is the ideal position of posterior teeth in relation to the crest of the mandibular ridge?
Buccolingually, lingual to the crest of the mandibular ridge
What enhances stability as the occlusal surfaces of teeth are closer to the ridge?
Small interarch distance
What type of tongue is unfavorable for denture stability?
Small, narrow tongue
What happens when posterior teeth are positioned on the upward incline of the mandible?
The tongue space is encroached upon, causing cramping of the tongue and lateral movement of the denture
What is the effect of flabby tissue on denture stability?
It reduces stability
What is the shape of the palatal vault that increases retention and decreases stability?
Flat
What is the relationship between surface area and adhesion?
Adhesion is directly proportional to surface area
What type of saliva adheres well to both denture base and mucosa?
Thick, ropy saliva
What is interfacial surface tension dependent on?
Size of the basal surface of the denture
What is the importance of a perfect fit of the denture base?
It affects interfacial surface tension
What is the effect of thick, ropy saliva on denture retention?
It forces the denture out of its correct position
What is the primary force that resists horizontal dislodging forces in denture retention?
Atmospheric pressure
What is the effect of a good fit of the periphery of the denture to the tissues?
Air cannot get in under the denture
What type of ridge form is ideal for maximum support, retention, and stability?
Square ridge
What is the consequence of border under extension in depth and width?
Air can get in under the denture
What is the role of adhesion, cohesion, and interfacial surface tension in denture retention?
Resisting vertical dislodging forces
What is the effect of disharmony in jaw sizes on denture retention?
It decreases denture retention
What is the primary force that resists the removal of a complete denture?
Adhesion and cohesion
What is the result of the interfacial surface tension in denture retention?
It increases the retention of the denture
What is the role of atmospheric pressure in denture retention?
It helps to retain the denture in place
What is the effect of a large arch size on denture retention?
It increases the retention of the denture
What is the relationship between the vault form and denture retention?
A high vault form decreases the retention of the denture
What is the effect of a polished surface of the denture on retention?
It increases the retention of the denture
What is the purpose of having the occlusal plane as near as possible to the ridge?
To enhance denture stability
What type of mucosa offers the most favorable prognosis for denture stability?
Mucosa of even, medium thickness
What contributes to excessive vertical and horizontal movements of the denture?
Flabby tissue
Why is a concave polished surface of denture preferred?
Because it tends to seat the denture
What is the result of forces directed to an inclined plane?
They are more dislodging
What enhances stability as the occlusal surfaces of teeth are closer to the ridge?
Small interarch distance
Why is balanced occlusion important in denture stability?
Because it enhances stability
What is the ideal position of posterior teeth in relation to the crest of the mandibular ridge?
Buccolingually, slightly lingual to the crest of the ridge
What happens when the polished surface of denture is convex?
The denture tends to unseat
What type of tongue is favorable for denture stability?
Broad thick tongue
Why is proper relief of hard areas under the denture important?
Because it prevents rocking and instability of the denture
What is the consequence of flabby tissue in denture stability?
Reduces denture stability
What is the relationship between the force of adhesion and the surface area of the denture?
The force of adhesion is directly proportional to the surface area.
What is the effect of a V-shaped palatal vault on denture retention and stability?
It decreases retention and increases stability.
What is the primary factor that determines the fit of the denture?
The accuracy of the impression.
What is the role of interfacial surface tension in denture retention?
It resists the separation of the denture from the mucosa.
What is the effect of thick ropy saliva on the retention of the denture?
It decreases the retention of the denture.
What is the ideal shape of the palatal vault for denture retention and stability?
U-shaped
What is the most unfavorable arch form for denture stability?
Flat arch form
What is the primary mechanism by which atmospheric pressure contributes to denture retention?
By creating a pressure difference between the fitting and non-fitting surfaces
What type of residual ridge resists well to lateral forces and enhances denture stability?
Ridge with high vertical walls
What is the effect of a large interarch distance on denture retention?
It decreases the retention by reducing the surface area
What is the ideal shape of the arch for maximum support, retention, and stability?
Square arch
What is the result of the interfacial surface tension in denture retention?
Firm seating of the denture
What is the ideal shape of the polished surface of a denture?
Flat
What is the role of the ridge form in denture retention?
It provides maximum support, retention, and stability
What is the result of forces directed to an inclined plane in denture retention?
Increased retention
What is the effect of disharmony in jaw sizes on denture retention?
It reduces the retention due to poor fit
What is the primary force that resists the removal of a complete denture?
Gravity
What is the primary force that resists vertical dislodging forces in denture retention?
Adhesion and cohesion
What is the effect of a higher occlusal plane in relation to the residual ridge?
Increased leverage action and lesser stability of the denture
What is the consequence of placing posterior teeth on the upward incline of the mandible in terms of denture stability?
Reduced stability due to the cramping of the tongue
What is the purpose of relief of hard areas under the denture?
To prevent rocking and instability of the denture
What is the consequence of a convex polished surface of the denture?
The denture is more likely to be unseated
What type of mucosa is most unfavorable for denture stability?
Flabby tissue contributing to excessive movements
What is the primary factor that enhances stability as the occlusal surfaces of teeth are closer to the ridge?
The minimized undesirable leverage action and tongue forces
What is the ideal direction of the occlusal plane in relation to the denture foundation area?
Parallel to the foundation area
What is the result of a small, narrow tongue on denture stability?
Reduced stability due to the adverse affect on tongue movement
What is the consequence of cusp interference?
Impaired denture stability
What is the purpose of making the occlusal plane as near as possible to the ridge?
To enhance denture stability
What type of polished surface of the denture tends to unseat the denture?
A convex surface
What is the primary advantage of having the occlusal plane as near as possible to the ridge?
Minimized undesirable leverage action and tongue forces
The primary force that resists horizontal dislodging forces in denture retention is adhesion, cohesion, and interfacial surface tension.
False
Border under extension in both depth and width causes poor denture retention due to the loss of atmospheric pressure.
True
A square arch form is the least favorable for denture retention.
False
The retention achieved from atmospheric pressure can resist both vertical and horizontal dislodging forces.
False
A high ridge with flat crest and parallel or nearly parallel sides is the least favorable for denture retention.
False
The larger the arch size, the lesser the support and retention.
False
A flat palate increases retention and stability of a denture.
False
The force of adhesion is proportional to the surface area of the denture base.
True
Thick, ropy saliva reduces the cohesive force between the denture and mucosa.
True
A perfect fit of the denture base is essential for interfacial surface tension.
True
The interfacial surface tension is inversely proportional to the size of the basal surface of the denture.
False
Closeness of denture adaptation decreases adhesion.
False
A flat vault form provides the most favorable prognosis for denture stability.
False
The residual ridge with high vertical walls (square ridge) provides the least favorable prognosis for denture stability.
False
A narrow V-shaped vault is favorable for the retention of dentures.
False
A Class I soft palate has a steep curvature and demonstrates significant muscular movement.
False
The undercut area is unimportant for denture retention.
False
A square arch form provides the least favorable prognosis for denture stability.
False
A thick flabby tissue contributes to denture stability.
False
The small narrow tongue enhances denture stability.
False
The interarch distance has no influence on denture stability.
False
Teeth placed over the crest of the mandibular ridge can cause tongue cramping.
True
A mucosa of even, medium thickness provides an unfavorable prognosis for denture stability.
False
The position of posterior teeth has no impact on denture stability.
False
Forces directed to an inclined plane are more dislodging than forces directed at right angle to the supporting basal seat.
True
The higher the occlusal plane in relation to the residual ridge, the lesser will be the leverage action.
False
The plane of occlusion should be perpendicular to the main direction of the denture foundation area.
False
A convex polished surface of the denture will tend to seat the denture.
False
Insufficient relief of hard areas under the denture will increase denture stability.
False
Balanced occlusion means harmonious contact between upper and lower teeth in only one position of the mandible.
False
Test your knowledge of retention and stability of complete dentures, including the forces that affect denture retention and the factors that influence denture stability. Learn about the importance of retention and stability in denture prosthodontics. Quiz based on the lecture notes of Dr. Fardos Rizk.
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