Overdentures & Abutment Selection

Optimal Abutment Teeth

• Best abutments: Canine & premolar
• Rationale: Superior root length, crown-to-root ratio, strategic position

 Ridge Assessment & Classification

Ridge Resorption Evaluation

• Assessment landmark: Incisive papilla position
• Clinical significance: Indicates extent of anterior ridge loss

Ridge Deformity Classification

• Siebert's Class I: Faciolingual (buccolingual) deficiency
• Clinical implication: Affects denture support and esthetics

Muscle Tone Classification

• Class I muscle tone: Characteristic of immediate dentures
• Clinical correlation: Affects initial denture stability

Vertical Dimension Relationships

VDR Formula

• Vertical Dimension at Rest (VDR) = VDO + Freeway space
• Clinical application: Determines proper jaw relationships

Esthetic Guidelines

Anterior Tooth Sizing

• Upper incisor width: 1/3rd of bizygomatic width
• Clinical significance: Provides natural proportions

Morphologic Changes

• Columella philtrum increase: Common change in edentulous patients
• Clinical impact: Affects facial support requirements

Occlusal Design Principles

Balanced Occlusion Relationships

• Increased condylar inclination → Increased compensating curve
• Clinical correlation: Maintains bilateral contact during function

Occlusal Plane Effects

• Shunting effect: Occurs when occlusal plane is low in incisor area
• Consequence: Improper load distribution

Functional Features

Tongue Training

• Training groove: Guides and trains tongue position
• Purpose: Improves speech and function

Stability Definition

• Denture stability: Resistance to lateral movement
• Clinical importance: Distinguishes from retention and support

 Complications & Design Issues

Tissue Problems

• Epulis fissuratum: Caused by labial flange overextension
• Prevention: Proper border extension limits

Connector Design

• Major connector beading: Achieves positive tissue contact
• Function: Improves tissue adaptation and comfort

Retromolar Pad Composition

• Contents: Superior constrictor + Buccinator + Temporal tendon
• Clinical significance: Important for posterior denture extension

Border Anatomy

• Distobuccal border: Influenced by coronoid process
• Masseteric notch: Formed by masseter muscle over buccinator
• Buccal frenum muscle: Levator anguli oris

Midline Considerations

• Midline relief: Depends on resiliency of midline suture
• Individual variation: Varies with suture mobility

 Occlusion Concepts

 Jaw Relation Records

Reference Planes & Landmarks

 Articulators & Theories

Occlusion & Jaw Relations synopsis

• Facebow (accurate hinge axis): Fully adjustable rods.
• Facebow use: Multiple unit restorations.
• Posselt: Described border movements.
• Fisher angle: Intersection of protrusive & non-working condylar paths (~5°).
• Curve of Spee: Anterior to posterior curve.
• Von Spee curve: Natural dentition.
• Sharp tooth pain: A-delta fibers.
• Sound change with anterior teeth position: “F” sounds.
• Centric relation: Posterior to intercuspal by 0.5–1 mm.

Surveying

Surveying is the process of analyzing a dental cast to determine the optimal path of insertion and identify undercuts, guiding planes, and suitable abutments for RPD design.

Components of a Dental Surveyor

Key Surveying Objectives

• Determine Path of Insertion

  • Establish a direction that allows smooth placement and removal of the prosthesis.

• Identify Height of Contour

  • Line encircling the greatest bulge of a tooth; helps in clasp placement.

• Locate Undercuts

  • Areas below the height of contour used for retention via clasps.

• Mark Guiding Planes

  • Flat surfaces prepared on abutment teeth to guide insertion and enhance stability.

• Evaluate Soft Tissue Undercuts

  • Helps avoid interference and discomfort during prosthesis placement.

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.

Material Selection for Pontics

High Yield

• Pontic for maxillary premolar: Modified ridge lap.
• Pontic for posterior maxilla: Trupontic/long pin pontic.
• Pontic for missing canine: Modified ridge lap > ovoid.
• Faciolingual pontic width: Determined by opposing centric stops.
• Pontic flex (3-unit vs single): 27× more.
• Arch form with longest cantilever: Tapered arch.