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NEET MDS Synopsis - Lecture Notes
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📖 Prosthodontics

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Applegate's Classification for edentulous arches
Prosthodontics

Applegate's Classification is a system used to categorize edentulous (toothless) arches in preparation for denture construction. The classification is based on the amount and quality of the remaining alveolar ridge, the relationship of the ridge to the residual ridges, and the presence of undercuts. The system is primarily used in the context of complete denture prosthodontics to determine the best approach for achieving retention, stability, and support for the dentures.

Applegate's Classification for edentulous arches:

1. Class I: The alveolar ridge has a favorable arch form and sufficient height and width to provide adequate support for a complete denture without the need for extensive modifications. This is the ideal scenario for denture construction.

2. Class II: The alveolar ridge has a favorable arch form but lacks the necessary height or width to provide adequate support. This may require the use of denture modifications such as flanges to enhance retention and support.

3. Class III: The ridge lacks both height and width, and there may be undercuts or excessive resorption. In this case, additional procedures such as ridge augmentation or the use of implants might be necessary to improve the foundation for the denture.

4. Class IV: The ridge has an unfavorable arch form, often with significant resorption, and may require extensive surgical procedures or adjuncts like implants to achieve a functional and stable denture.

5. Class V: This is the most severe classification where the patient has no residual alveolar ridge, possibly due to severe resorption, trauma, or surgical removal. In such cases, the creation of a functional and stable denture may be highly challenging and might necessitate advanced surgical procedures and/or the use of alternative prosthetic options like over-dentures with implant support.

It's important to note that this classification is a guide, and individual patient cases may present with a combination of features from different classes or may require customized treatment plans based on unique anatomical and functional requirements.

Mental Attitude of Patients for Complete Dentures
Prosthodontics

The mental attitude of patients towards complete dentures plays a significant role in the success of their treatment. Understanding these attitudes can help dental professionals tailor their approach to meet the needs and expectations of their patients. Here are the four primary mental attitudes that patients may exhibit:

1. Philosophical (Ideal Attitude)

  • Characteristics:
    • Accepts the dentist's judgment without question.
    • Exhibits a rational, sensible, calm, and composed disposition.
    • Open to discussing treatment options and understands the importance of oral health.
  • Implications for Treatment:
    • This type of patient is likely to follow the dentist's recommendations and cooperate throughout the treatment process.
    • They are more likely to have realistic expectations and be satisfied with the outcomes.

2. Indifferent

  • Characteristics:
    • Shows little concern for their oral health.
    • Seeks treatment primarily due to pressure from family or friends.
    • Requires additional time and education to understand the importance of dental care.
    • Their attitude can be discouraging to dentists, as they may not fully engage in the treatment process.
  • Implications for Treatment:
    • Dentists may need to invest extra effort in educating these patients about the benefits of complete dentures and the importance of oral health.
    • Building rapport and trust is essential to encourage a more proactive attitude towards treatment.

3. Critical/Exacting

  • Characteristics:
    • Has previously had multiple sets of complete dentures and tends to find fault with everything.
    • Often has high expectations and may be overly critical of the treatment process.
    • May require medical consultation due to previous experiences or health concerns.
  • Implications for Treatment:
    • Dentists should be prepared to address specific concerns and provide detailed explanations about the treatment plan.
    • It is important to manage expectations and ensure that the patient understands the limitations and possibilities of denture treatment.

4. Skeptical/Hysterical

  • Characteristics:
    • Has had negative experiences with previous treatments, leading to doubt and skepticism about the current treatment.
    • Often presents with poor oral health, resorbed ridges, and other unfavorable conditions.
    • May exhibit anxiety or hysteria regarding dental procedures.
  • Implications for Treatment:
    • Building trust and confidence is crucial for these patients. Dentists should take the time to listen to their concerns and provide reassurance.
    • A gentle and empathetic approach is necessary to help alleviate fears and encourage cooperation.
    • It may be beneficial to involve them in the decision-making process to empower them and reduce anxiety.
Kennedy's Classification of Edentulous Arches
Prosthodontics

Kennedy's Classification is a system used in dentistry to categorize the edentulous spaces (areas without teeth) in the mouth of a patient who is fully or partially edentulous. This classification system helps in planning the treatment, designing the dentures, and predicting the outcomes of denture therapy. It was developed by Dr. Edward Kennedy in 1925 and is widely used by dental professionals.

The classification is based on the relationship between the remaining teeth, the residual alveolar ridge, and the movable tissues of the oral cavity. It is particularly useful for patients who are wearing or will be wearing complete or partial dentures.

There are four main classes of Kennedy's Classification:

1. Class I: In this class, the patient has a bilateral edentulous area with no remaining teeth on either side of the arch. This means that the patient has a full denture on the upper and lower jaws with no natural tooth support.

2. Class II: The patient has a unilateral edentulous area with natural teeth remaining only on one side of the arch. This could be either the upper or lower jaw. The edentulous side has a complete denture that is supported by the teeth on the opposite side and the buccal (cheek) and lingual (tongue) tissues.

3. Class III: There is a unilateral edentulous area with natural teeth remaining on both sides of the arch, but the edentulous area does not include the anterior (front) teeth. This means the patient has a partial denture on one side of the arch, with the rest of the teeth acting as support for the denture.

4. Class IV: The patient has a unilateral edentulous area with natural teeth remaining only on the anterior region of the edentulous side. The posterior (back) section of the same side is missing, and there may or may not be teeth on the opposite side. This situation requires careful consideration for the design of the partial denture to ensure stability and retention.

Each class is further divided into subcategories (A, B, and C) to account for variations in the amount of remaining bone support and the presence or absence of undercuts, which are areas where the bone curves inward and can affect the stability of the denture.

- Class I (A, B, C): Variations in the amount of bone support and presence of undercuts in the fully edentulous arches.
- Class II (A, B, C): Variations in the amount of bone support and presence of undercuts in the edentulous area with natural teeth on the opposite side.
- Class III (A, B, C): Variations in the amount of bone support and presence of undercuts in the edentulous area with natural teeth on the same side, but not in the anterior region.
- Class IV (A, B, C): Variations in the amount of bone support and presence of undercuts in the edentulous area with natural teeth remaining only in the anterior region of the edentulous side.

Understanding a patient's Kennedy's Classification helps dentists and dental technicians to create well-fitting and functional dentures, which are crucial for the patient's comfort, speech, chewing ability, and overall oral health.

Finish lines
Prosthodontics

Finish lines are the marginal configurations at the interface between a restoration and the tooth structure that are intended to be refined and polished to a smooth contour. In prosthodontics, they are crucial for the proper adaptation and seating of restorations, as well as for maintaining the health of the surrounding soft and hard tissues. Finish lines can be classified in several ways, such as by their location, purpose, and the burs used to create them. Here's an overview:

1. Classification by Width:
a. Narrow Finish Lines: These are typically 0.5mm wide or less and are often used in areas where the restoration margin is tight against the tooth structure, such as with metal-ceramic restorations or in cases with minimal tooth preparation.
b. Moderate Finish Lines: These are 0.5-1.5mm wide and are commonly used for most types of restorations, providing adequate space for a good margin and seal.
c. Wide Finish Lines: These are 1.5mm wide or more and are often used in areas with less than ideal tooth preparation or when a wider margin is necessary for material manipulation or when there is a concern about the stability of the restoration.

2. Classification by Location and Application:
a. Shoulder Finish Line: This finish line is at a 90-degree angle to the tooth structure and is often used for metal-ceramic and all-ceramic restorations. It provides good support and can be easily visualized and finished.
b. Knife-Edge Finish Line: This is a very thin finish line that is beveled at an approximately 45-degree angle to the tooth structure. It is typically used for all-ceramic restorations and is designed to mimic the natural tooth contour, providing excellent esthetics.
c. Feather Edge Finish Line: Also known as a chamfer, this finish line is beveled at approximately 90-degrees to the tooth structure. It is used in situations where the tooth structure is not ideal for a shoulder margin, and it helps to distribute the forces evenly and reduce the risk of tooth fracture.
d. Butt-Joint Finish Line: This is when the restoration margin is placed directly against the tooth structure without any bevel. It is often used in the lingual areas of anterior teeth and in situations where there is minimal space for a margin.

3. Classification by Function:
a. Functional Finish Lines: These are placed where the restoration will be subject to significant occlusal or functional stresses. They are designed to enhance the durability of the restoration and are usually placed at or slightly below the height of the free gingival margin.
b. Esthetic Finish Lines: These are placed to achieve a high level of cosmetic appeal and are often located in the facial or incisal areas of anterior teeth. They are typically knife-edge margins that are highly polished.

Advantages and Disadvantages:
- Narrow finish lines can be more challenging to clean and may be less visible, potentially leading to better esthetics and less irritation of the surrounding tissues. However, they may also increase the risk of recurrent decay and are more difficult to achieve a good margin seal with.
- Moderate finish lines are easier to clean and provide a better margin seal, but may be more visible and can potentially lead to increased tooth sensitivity.
- Wide finish lines are more forgiving for marginal adaptation and are easier to clean, but they can be less esthetic and may require more tooth reduction.

Burs Used:
- The choice of bur for creating finish lines depends on the restoration material and the desired margin design. For example:
a. Diamond Burs: Typically used for creating finish lines on natural tooth structures, especially for knife-edge margins on ceramic restorations, due to their ability to produce a smooth and precise finish.
b. Carbide Burs: Often used for metal-ceramic restorations, as they are less likely to chip the ceramic material.
c. Zirconia-Specific Burs: Used for zirconia restorations to prevent chipping or fracture of the zirconia material.

When creating finish lines, the dentist must consider the patient's oral health, the type of restoration, the location in the mouth, and the desired functional and esthetic outcomes. The correct selection and preparation of the finish line are essential for the longevity and success of the restoration.