Podcast
Questions and Answers
What is the primary reason for high failure rates in extension-base removable partial dentures (RPDs)?
What is the primary reason for high failure rates in extension-base removable partial dentures (RPDs)?
- Poor plaque control around the abutments
- Inadequate extension of the denture base
- Suboptimal framework design
- Difference in hard tooth and soft tissue support leading to abutment movement (correct)
- Lack of patient recall appointments for adjustments
During abutment evaluation for an extension-base RPD, why might radiographs alone be insufficient?
During abutment evaluation for an extension-base RPD, why might radiographs alone be insufficient?
- Radiographs can be misleading; clinical examination with a periodontal probe is essential. (correct)
- Radiographs always reveal adequate bone support.
- Radiographs clearly show the need for splinting.
- Radiographs accurately depict periodontal health.
- Radiographs provide a complete view of root morphology.
Which of the following pre-prosthetic surgical procedures is LEAST likely to be necessary for an extension-base RPD?
Which of the following pre-prosthetic surgical procedures is LEAST likely to be necessary for an extension-base RPD?
- Extraction of impacted third molars
- Creating space for denture components
- Tori removal (correct)
- Block repositioning with surgery
- Tuberosity reduction
What is a rationale for ensuring complete coverage of the available supporting area, such as the pear-shaped pad and buccal shelf, during impression taking for an extension-base RPD?
What is a rationale for ensuring complete coverage of the available supporting area, such as the pear-shaped pad and buccal shelf, during impression taking for an extension-base RPD?
In the context of extension-base RPDs, what is the primary purpose of considering the shape of the roots of potential abutment teeth?
In the context of extension-base RPDs, what is the primary purpose of considering the shape of the roots of potential abutment teeth?
When might a fixed partial denture be considered a possible treatment option during the evaluation of abutments for an extension-base RPD?
When might a fixed partial denture be considered a possible treatment option during the evaluation of abutments for an extension-base RPD?
Why is the altered cast technique utilized in the context of impression making for extension-base RPDs?
Why is the altered cast technique utilized in the context of impression making for extension-base RPDs?
What is the significance of block repositioning as a pre-prosthetic surgical procedure?
What is the significance of block repositioning as a pre-prosthetic surgical procedure?
What factor most significantly impacts the long-term success of an extension-base RPD?
What factor most significantly impacts the long-term success of an extension-base RPD?
Why is evaluating the need for splinting abutment teeth an important step in planning an extension-base RPD?
Why is evaluating the need for splinting abutment teeth an important step in planning an extension-base RPD?
Why is the utilization of third molars generally discouraged in pre-prosthetic surgery for removable partial dentures?
Why is the utilization of third molars generally discouraged in pre-prosthetic surgery for removable partial dentures?
Which of the following is the MOST important consideration when choosing impression materials for an extension-base RPD?
Which of the following is the MOST important consideration when choosing impression materials for an extension-base RPD?
In the context of pre-prosthetic surgery, what is a 'tuberosity trim' designed to achieve?
In the context of pre-prosthetic surgery, what is a 'tuberosity trim' designed to achieve?
Why is a lack of patient recall a factor in the high failure rate of extension-base RPDs?
Why is a lack of patient recall a factor in the high failure rate of extension-base RPDs?
What is the potential consequence of inadequate denture bases in extension-base RPDs?
What is the potential consequence of inadequate denture bases in extension-base RPDs?
In the context of impression materials used for RPD fabrication, what does 'equal accuracy if handled correctly' imply?
In the context of impression materials used for RPD fabrication, what does 'equal accuracy if handled correctly' imply?
Why is poor design a factor in the high failure rate of extension-base RPDs?
Why is poor design a factor in the high failure rate of extension-base RPDs?
Why is noting the shape of the roots during abutment evaluation important?
Why is noting the shape of the roots during abutment evaluation important?
In impression taking, what is the significance of the pear-shaped pad?
In impression taking, what is the significance of the pear-shaped pad?
What is the main goal of pre-prosthetic surgery?
What is the main goal of pre-prosthetic surgery?
Flashcards
Primary reason for RPD failure
Primary reason for RPD failure
Difference in hard tooth and soft tissue support, causing tipping, rocking and torquing of abutments.
How to evaluate abutments?
How to evaluate abutments?
Radiographs can be misleading, so you should use your periodontal probe.
Examples of Pre-Prosthetic Surgery
Examples of Pre-Prosthetic Surgery
Surgical block repositioning, tuberosity trims, designs for limited space.
Rationale for complete RPD coverage
Rationale for complete RPD coverage
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Block repositioning with surgery
Block repositioning with surgery
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Tuberosity trims
Tuberosity trims
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Altered cast technique
Altered cast technique
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Study Notes
Bernoulli Equation
- Describes fluid behavior with relationships between pressure, velocity, and elevation.
- Formula: $\frac{P_1}{\rho} + \frac{V_1^2}{2} + gz_1 = \frac{P_2}{\rho} + \frac{V_2^2}{2} + gz_2$
Bernoulli Equation Assumptions
- Flow is steady state.
- Fluid is incompressible
- No energy loss due to friction.
- Flow occurs along a streamline.
Friction Correction to Bernoulli Equation
- Accounts for energy loss due to friction.
- Formula: $\frac{P_1}{\rho} + \frac{V_1^2}{2} + gz_1 = \frac{P_2}{\rho} + \frac{V_2^2}{2} + gz_2 + h_f$
- $h_f$ represents the head loss due to friction.
Pump Work in Bernoulli Equation
- Includes the energy added to fluid by a pump.
- Formula is: $\frac{P_1}{\rho} + \frac{V_1^2}{2} + gz_1 + W_p = \frac{P_2}{\rho} + \frac{V_2^2}{2} + gz_2 + h_f$
- $W_p$ is the work done by the pump.
Turbine Work in Bernoulli Equation
- Accounts for energy extracted from fluid by a turbine.
- Equation: $\frac{P_1}{\rho} + \frac{V_1^2}{2} + gz_1 = \frac{P_2}{\rho} + \frac{V_2^2}{2} + gz_2 + h_f + W_t$
- $W_t$ is the work done by the turbine.
Example: Pumping Water Through a Pipe
- Water at $20^\circ C$ is pumped at a rate of 2 $\frac{Kg}{s}$.
- Properties of water at $20^\circ C$: $\rho$ = 998 $\frac{Kg}{m^3}$, $\mu$ = 0.001 $Pa \cdot s$
- A motor supplies 3 Kw of power to the pump.
- Inlet pressure $P_1$ is 1 atmosphere
- Pipe is 2-inch schedule 40.
- Schedule 40 2-inch pipe dimensions: $ID = 0.0525 m$, $A = 0.002165 m^2$
- Goal: Determine the pressure at $P_2$?
Mass Balance
- Mass balance is used to find the velocity.
- $\dot{m} = \rho V A$
- $2 \frac{Kg}{s} = 998 \frac{Kg}{m^3} \cdot V \cdot 0.002165 m^2$
- $V = 0.9255 \frac{m}{s}$
Applying Bernoulli Equation
- $\frac{P_1}{\rho} + \frac{V_1^2}{2} + gz_1 + W_p = \frac{P_2}{\rho} + \frac{V_2^2}{2} + gz_2 + h_f$
- $V_1 = V_2$
- $z_1 = 0, z_2 = 2 m$
- Simplified equation: $\frac{P_1}{\rho} + W_p = \frac{P_2}{\rho} + gz_2 + h_f$
Pump Work Calculation
- $W_p = \frac{P_{shaft}}{\dot{m}} = \frac{3000 \frac{J}{s}}{2 \frac{Kg}{s}} = 1500 \frac{J}{Kg}$
Head Loss Calculation
- $h_f = \frac{fLV^2}{2D}$
- Friction factor needs to be determined.
Reynold's Number Calculation
- Used to determine the nature of the flow, laminar or turbulent
- $Re = \frac{\rho V D}{\mu} = \frac{998 \frac{Kg}{m^3} \cdot 0.9255 \frac{m}{s} \cdot 0.0525m}{0.001 Pa \cdot s} = 48440$
Friction Factor Determination
- Assume smooth pipe: $f = 0.004$
- $h_f = \frac{0.004 \cdot 20 m \cdot (0.9255 \frac{m}{s})^2}{2 \cdot 0.0525m} = 0.65 \frac{m^2}{s^2}$
Solving for $P_2$
- $\frac{101325 Pa}{998 \frac{Kg}{m^3}} + 1500 \frac{J}{Kg} = \frac{P_2}{998 \frac{Kg}{m^3}} + 9.81 \frac{m}{s^2} \cdot 2m + 0.65 \frac{m^2}{s^2}$
- $P_2 = 150000 Pa = 1.48 \ atm$
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