Definition of Major Connector:

A major connector is the main part of a removable partial denture

(RPD) that joins the components on one side of the arch to those on
the opposite side, providing unification and stability to the
prosthesis.

🔹 Key Functions:

 Unites all parts of the denture into a single unit

 Distributes functional loads evenly across the arch
 Provides rigidity (should not flex during function)
 Supports other components like minor connectors, rests, and
clasps

🔹 Common Types:

� Maxillary Major Connectors:

 Palatal Strap
 Palatal Plate
 U-Shaped (Horseshoe)
 Anteroposterior Palatal Strap
 Complete Palatal Coverage

� Mandibular Major Connectors:

 Lingual Bar
 Lingual Plate
 Sublingual Bar
 Labial Bar (rare)

🔹 Requirements of a Good Major Connector:

1. Rigid
2. Does not interfere with tongue or soft tissues
3. Provides comfort and doesn’t cause speech issues
4. Has smooth, rounded borders
5. Provides indirect retention, if applicable
 RETAINERS FOR EACH CLASS ;

Kennedy
Support Type Common Retainers Notes
Class
RPI (Rest, Proximal Plate, I-bar) / RPA Mesial rests to reduce
I Tooth–tissue
(Rest, Proximal Plate, Akers clasp) torque
Indirect retainer on
II Tooth–tissue RPI / RPA (distal side) + Akers clasp
opposite side
Tooth- Most stable; no need for
III Akers / Embrasure clasp
supported stress breakers
Tooth- Focus on esthetics and
IV Akers / Esthetic clasps
supported rigid connectors

2; Applegate’s Rules (Simplified):

1. Classification is determined after extractions.

→ Only remaining teeth are considered.
2. Third molars are considered only if functional.
→ If not present or not used, ignore them.
3. Second molars are considered if used for support.
→ Include only if they're part of the plan.
4. Most posterior edentulous area determines the classification.
5. Additional edentulous areas are called modifications.
6. The number of modifications is based on the number of additional edentulous areas
(not teeth).
7. No modification areas in Class IV.
→ Class IV (anterior edentulous area crossing midline) can't have modifications.
8. Both arches are classified separately.

3; designing partial dentures for each Kennedy class:

🔹 General Design Components of RPD:

1. Major connector – unites all parts of the denture
2. Minor connector – joins components to major connector
3. Rest – prevents vertical movement toward tissue
4. Direct retainer (clasp assembly) – resists dislodgement
5. Indirect retainer – prevents rotational movement
 6. Denture base – supports the prosthetic teeth

🔸 Kennedy Class I
(Bilateral distal extension – posterior teeth missing on both sides)

🔹 Design Focus: Tissue support is critical.

 Major Connector: Maxilla – palatal strap or plate; Mandible – lingual bar or plate
 Direct Retainers: On the most posterior abutment teeth (premolars or canines)
 Rests: Mesial rests on abutment teeth (to prevent distal tipping)
 Indirect Retainers: Required (usually on canines or incisors)
 Denture Base: Must be extended for maximum tissue support

✅ Special Consideration: Use altered cast technique for better fit and support.

🔸 Kennedy Class II
(Unilateral distal extension – posterior teeth missing on one side)

🔹 Design Focus: Mixed support (teeth and tissue)

 Major Connector: Similar to Class I

 Direct Retainers: On abutments adjacent to the edentulous area and opposite side
 Rests: Mesial on distal extension side
 Indirect Retainer: On the opposite side (to prevent rotation)
 Denture Base: Extended over edentulous ridge

✅ Consider stress-releasing clasp (like RPI or RPA) on distal extension side.

🔸 Kennedy Class III

(Unilateral bounded edentulous space)

🔹 Design Focus: Tooth-supported — most stable.

 Major Connector: Any suitable design

  Direct Retainers: On both abutment teeth
 Rests: On adjacent teeth (mesial or distal, as needed)
 Indirect Retainer: Not usually needed
 Denture Base: Less tissue coverage; rigid base possible

✅ Simplest and most stable design – often no need for special stress-releasing designs.

🔸 Kennedy Class IV
(Single anterior edentulous area crossing the midline)

🔹 Design Focus: Aesthetics and stability.

 Major Connector: Maxilla – full palatal plate; Mandible – lingual plate or bar
 Direct Retainers: Posterior abutment teeth on both sides
 Rests: Distal rests on canines or first premolars
 Indirect Retainer: Optional, depending on extension
 Denture Base: Must be strong and thin; often metal/acrylic combo

✅ Teeth arrangement must prioritize aesthetics — clear clasps or hidden retentive elements may
be used.

✅ Tips for All Classes:

 Use surveyed abutments to guide path of insertion.
 Consider reciprocation, stability, and retention in all designs.
 Always provide maximum coverage in distal extension cases for support.
Obturator Prosthesis
: An obturator prosthesis is a special type of maxillofacial prosthesis used to close the defect (hole or
communication) between the oral and nasal cavities created after surgical removal of part of the maxilla
(upper jaw).
Function of Obturator Prosthesis:

Restores speech (prevents hypernasal voice)

Improves swallowing and chewing

Separates oral and nasal cavities to prevent food/liquid from entering the nose

Improves facial aesthetics and support

TYPES OF ARTICULATOR

1. Class I — Simple Hinge Articulator

Movement: Only vertical opening and closing (hinge).

No lateral/protrusive movement.

Use: Basic diagnostic models.

2. Class II — Fixed Condylar Path

Movement: Vertical + fixed protrusive/lateral paths.

Condylar path is preset (not adjustable).

Use: Limited prosthodontics.

3. Class III — Semi-Adjustable Articulator ️

Movement: Simulates most mandibular movements.

Adjustable condylar guidance and Bennett angle.

Use: Most common in crown, bridge, and complete dentures.

4. Class IV — Fully Adjustable Articulator ️

Movement: Reproduces exact mandibular movements.

Records true hinge axis, customized condylar paths.

Use: Full-mouth rehabilitation, complex cases.

spot- types of articulator

dental surveyor

Important uses:

1. Determine path of insertion.

2. Detect undercuts.

3. Plan clasp placement.

4. Draw survey lines.

5. Guide rest seat prep.

SPOT 10;

� Definition of CPD (Cast Partial Denture):

A Cast Partial Denture is a removable dental prosthesis made of metal framework (usually
cobalt-chromium) and acrylic, designed to replace missing teeth in patients who still have some
natural teeth remaining.

It differs from an acrylic partial denture in that the framework is cast from metal, which
provides superior strength, fit, and durability

Part Function

Major Connector Joins components on both sides of the arch; provides rigidity

Minor Connector Connects other components (rests, clasps) to the major connector

Direct Retainer Prevents dislodgement; usually a clasp system gripping abutment teeth

Indirect Retainer Prevents rotational movement (mainly in distal extension cases)

Rest Provides vertical support; placed on prepared surfaces of abutment teeth

Denture Base Supports the artificial teeth and transmits forces to underlying tissues

Artificial Teeth Replace missing natural teeth

Proximal Plate Contacts guiding planes on abutment teeth; provides bracing and guidance

Functions of a Cast Partial Denture:

1. Restores mastication (chewing)

2. Improves aesthetics and speech
3. Prevents drifting and over-eruption of remaining teeth
4. Provides comfort and stability
5. Maintains arch integrity
6. Evenly distributes occlusal forces

🔹 Indications of CPD:

1. Multiple missing teeth in one or both arches

2. Kennedy Class I, II, III, and IV situations
3. When abutment teeth are present and suitable for support
4. Long-span edentulous areas where fixed prosthesis is not ideal
5. Patient prefers a removable option over implants or bridges
6. Interim prosthesis during healing or implant stages
7. Financial or medical contraindications to fixed restorations
✅ Definition of Balanced Occlusion:

Balanced occlusion is the simultaneous bilateral contact of the upper and lower teeth in
centric relation and during all excursive (lateral and protrusive) movements of the mandible.

📌 In simple terms:
All teeth should touch at the same time during all jaw movements — right, left, forward, and
back — to maintain denture stability.

� Balanced Occlusion in Prosthodontics:

 Mainly applied in complete denture prosthodontics.

 Helps maintain denture stability during function.
 Prevents tipping, rocking, or displacement of the dentures.
 Requires proper arrangement of artificial teeth and occlusal adjustments.
 Often achieved using semi-adjustable articulators and specific occlusal schemes (e.g.,
Monson’s curve, lingualized occlusion).

💬 If asked "Why is balanced occlusion important in complete dentures?", you can say:

"Because there are no periodontal ligaments in complete dentures, we need equal contact during
all movements to distribute forces evenly and keep the denture stable."
SPOT 26;

Definition:

An implant-supported overdenture is a removable denture that is retained and/or

supported by dental implants placed in the jawbone, instead of (or in addition to) just resting
on the gums and underlying bone.

📌 It "snaps" onto implants using attachments like locators, balls, or bars, providing improved
stability and retention.

� Implant-Supported Overdenture in Prosthodontics:

 Commonly used in edentulous patients, especially in the mandible.

 Provides better retention, function, and comfort compared to conventional dentures.
 Helps prevent bone resorption by transmitting functional forces to the bone via
implants.
 Improves speech, chewing efficiency, and patient confidence.
 Attachments can be:
→ Stud type (e.g. Locator, Ball)
→ Bar type (Bar with clips)
→ Magnetic systems

💬 If asked “How many implants are needed for a mandibular overdenture?”, say:

"At least 2 implants in the anterior mandible are usually sufficient for good support and
retention."

For the maxillary arch, more implants are generally needed than in the mandible

Typically 4 to 6 implants are placed.

Design Considerations:

 May require palatal coverage or horseshoe-shaped denture depending on:

 Bar-supported designs .

💬 If asked “Why are more implants needed in the maxilla?”, say:

"Because the maxillary bone is less dense, and the forces from speech, chewing, and gravity
require more support for long-term stability."
SPOT 2:

Sodium Alginate
Definition:
Sodium alginate is a salt of alginic acid (a polysaccharide from brown seaweed), used as the main gelling
agent in irreversible hydrocolloid impression materials.
Uses of Sodium Alginate
1. Dental impressions – chief component of alginate impression material.
2. Food industry – as a thickener, stabilizer, and gelling agent.
3. Pharmaceuticals – in tablets and antacids (forms a protective gel in the stomach).
4. Textile industry – as a thickening agent in printing pastes.
5. Wound dressings – in alginate dressings for absorption and healing.
Properties of Sodium Alginate (in dental use)
1. Irreversible gel formation
2. Elastic and flexible
3. Biocompatible and safe
4. Hydrophilic (mixes easily with water)
5. Quick setting time
Advantages
1. Easy to mix and use
2. Comfortable for patients
3. Good surface detail for impressions
4. Low cost and widely available
5. Non‑toxic and safe

What makes it common to use

1- easy to handle
2- economical
3- quick‑setting
4- comfortable
5- safe for taking accurate dental impressions.
SPOT 4;
Zinc Oxide Eugenol (ZOE)
Composition:
Powder: Zinc oxide, white rosin, zinc acetate, zinc stearate
Liquid: Eugenol, oil of cloves, olive oil, or other oils
Special Properties of Zinc Oxide Eugenol (ZOE)
1. Sedative effect on the pulp (soothing action)
2. Good dimensional stability
3. Antibacterial property due to eugenol

SPOT 5;
Abutment Options for Implant‑Retained Crown
1. Prefabricated abutments – ready‑made, commonly titanium.
2. Custom abutments – individually made for optimal fit/angulation.
3. Angled abutments – correct implant angulation issues.
4. Esthetic abutments – zirconia or ceramic for anterior regions.

Advantages of Screw‑Retained Implants

1. Easy retrieval for repair or hygiene.
2. No risk of cement residue causing peri‑implantitis.
3. Secure mechanical retention.
4. Precise seating with minimal risk of misfit.
Reverse Action (Hairpin) Clasp
A clasp design for removable partial dentures where the retentive arm approaches the undercut from
the opposite (occlusal) direction by looping in a hairpin shape.
Uses:
1. For deep undercuts near the gingival margin.
2. When conventional clasp approaches are not possible.
3. Provides good esthetics by minimizing visible metal.
Other clasp design
in Removable Partial Dentures (RPD), the main clasp designs are:
1. Circumferential clasp (Akers)
2. Ring clasp
3. Embrasure clasp (Double Akers)
4. Back‑action clasp
5. Combination clasp
6. Bar clasp (Roach)
7. Reverse action (Hairpin) clasp
extraoral circumferential direct clasp

In Removable Partial Denture (RPD) terminology,

an extra‑oral circumferential direct clasp is a type of suprabulge clasp that approaches the undercut
from above the height of contour and encircles more than 180° of the tooth from the outside
(extra‑oral) surface.

Key Points

Type: Suprabulge clasp

Approach: From above survey line

Coverage: Encircles >180° of tooth

Use: Provides strong retention where esthetics and tooth morphology allow
Definition:

An embrasure clasp is a direct retainer used in bilaterally edentulous situations where no edentulous
space exists between two adjacent abutment teeth.

Features:

1-Consists of two Akers (circumferential) clasps placed back‑to‑back on adjacent teeth.

2-Requires additional tooth reduction to provide space for metal bulk.

3-Provides retention and stability on both sides of the arch.

Use:

Commonly used in Kennedy Class II and III RPDs to clasp adjacent teeth where no edentulous space is
present.
clasp assembly components in a Removable Partial Denture (RPD) — specifically
circumferential clasp (suprabulge) on the buccal side and bar clasp (infrabulge) on the lingual
side.
Key Parts Labeled

Support → from the occlusal rest (occlusal third)

Stabilization → from the reciprocal arm (middle third)

Retention → from the retentive arm engaging an undercut (gingival third)

Explanation

It demonstrates how a clasp engages a tooth at different thirds:

Occlusal third → support (rest seat)

Middle third → stabilization (bracing/recriprocal arm)

Gingival third → retention (flexible retentive arm tip)

Labial Bar (Clasp in RPD)

Definition:

A labial bar is an infrabulge clasp that approaches the undercut from the labial (facial) surface of
anterior teeth.

Features:

1-Shaped like a bar crossing the gingival area on the labial side.

2-Used when severe lingual inclinations of anterior teeth prevent lingual clasp placement.

3-Must maintain adequate gingival clearance (usually 3–4 mm).

Uses

1. For anterior teeth with lingual tilt.

2. When lingual undercuts are absent.

3. To improve esthetics/retention in anterior RPDs.

metal framework of a Removable Partial Denture (RPD) seated on a cast.
Key Components Seen

1-Occlusal rests on posterior teeth (metal extensions sitting on occlusal surfaces for support).

2-Major connector (broad metal plate uniting the left and right sides of the denture).

3-Minor connectors linking the rests/clasps to the major connector.

4-Open spaces where denture base and artificial teeth will later be attached with acrylic resin.