What is an in·Di·rect retainer?
in·di·rect re·tain·er a part of a removable partial denture that assists the direct retainers in preventing occlusal displacement of the distal extension bases by functioning through lever action on the opposite side of the fulcrum line. Farlex Partner Medical Dictionary © Farlex 2012 in·di·rect re·tain·er (in-di-rekt rĕ-tānĕr)
What is the difference between a direct and an indirect retainer?
C, With direct retainers (dr) at the fulcrum, the lifting force will depress one end of the beam and elevate the other end. D, With both direct and indirect retainers (ir) functioning, the lifting force will not displace beam. The farther the indirect retainer is from the fulcrum, the more efficiently it should control movement.
How do FIFF indirect retainers prevent displacement?
f Indirect retainers do not prevent displacement towards the ridge. This movement is resisted by the occlusal rest on the abutment tooth and by full extension of the saddle to gain maximum support from the residual ridge.
What are the different types of retainers?
Direct retainers Indirect retainers Definition Classification Principles of design Extracoronal retainers Types Definition Factors affecting types of indirect Requirements retainers 3.
How does indirect retainer work?
Indirect retainers do not prevent displacement towards the ridge. This movement is resisted by the occlusal rest on the abutment tooth and by full extension of the saddle to gain maximum support from the residual ridge.
Which type of rest acts indirect retainer?
This location is at 90 degrees to the fulcrum line. A cingulum rest also can be used as an effective indirect retainer.
When do you use indirect retainers?
Indirect retainers are proximal plates on second premolars and occlusal rests located on first premolars. A secondary function of auxiliary occlusal rest assemblies is to prevent settling of the anterior portion of the major connector and to provide stabilization against horizontal rotation.
How do you know if your retainer is indirect?
1:104:27Indirect retainer for the removable partial denture - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe indirect retainer is normally located on the side opposite that of the distal extension base.MoreThe indirect retainer is normally located on the side opposite that of the distal extension base.
Where do you put the indirect retainer?
The indirect retainer is located on the opposite side of the retentive fulcrum line from the mucosa supported base. Most frequently, indirect retainers are placed on canines or the mesial fossa of first premolars.
Which Kennedy design must include indirect retainer?
All Kennedy Class I, Class II, and long span Class IV removable partial dentures require effective indirect retention. When the posterior portion of a Kennedy Cl I or Cl II RPD is subjected to occlusally directed dislodging forces: 1.
What are the functions of direct retainers?
Direct retainer: that component of a removable partial denture used to retain and prevent dislodgment, consisting of a clasp assembly or precision attachment.
What is direct retention?
DEFINITIONS. RETENTION is resistance to movement of a denture away from the teeth and/or tissues along the path of placement of the prosthesis. Most retention of RPDs is provided by DIRECT RETAINERS which are clasp assemblies or attachments applied to an abutment tooth to retain an RPD in position. 1.
What provides indirect retention in RPD?
A secondary fulcrum line is usually established when partial denture design includes indirect retention.
When do you use half and half clasp?
6-the half and half clasp: The half and half clasp is a modification of the circlet clasp with the reciprocal arm coming from one direction and the retentive arm from the other. Two rests are used for this clasp. It is used on molars and premolars.
When do you use Aker clasp?
RPA clasp; Akers clasp This clasp arises from the proximal plate and terminates in the mesiobuccal undercut. It is used when there is insufficient vestibule depth or when a severe tissue undercut exists.
What is an occlusal rest?
An occlusal rest consists of two component parts-a horizontal portion and a vertical portion. The horizontal portion is that part which rests on the abutment tooth and transmits the forces of mastication to the tooth. The vertical com- ponent connects the horizontal part of the rest to the partial denture base.
What is an occlusal rest?
An occlusal rest consists of two component parts-a horizontal portion and a vertical portion. The horizontal portion is that part which rests on the abutment tooth and transmits the forces of mastication to the tooth. The vertical com- ponent connects the horizontal part of the rest to the partial denture base.
When do you use an Embrasure clasp?
Embrasure clasp This design is most frequently used in cases of unilateral edentulous span of an unmodified Kennedy Class II or Class III partial denture, on the side of the arch where there is no edentulous space.
What is combination syndrome?
Combination syndrome (CS) is a dental condition that is commonly seen in patients with a completely edentulous maxilla and partially edentulous mandible with preserved anterior teeth.
What is proximal plate?
Proximal plates extend from the proximal facial line angle of the tooth to, or slightly past, the proximal lingual line angle of the tooth. They are thin mesiodistally and taper slightly toward the occlusal (incisal). They extend from the occlusal/incisal of the tooth to the major connector.
fLifting force will displace entire beam in absence of retainers
fWith direct retainers (dr) at fulcrum, lifting force will depress one end of beam and elevate other end.
fMechanical disadvantage of the denture design
fThe clasp is always nearer to the indirect retainer (fulcrum) than is the displacing force. The clasp is therefore working at a mechanical disadvantage relative to the displacing force.
fSupport for the indirect retainer
f Tooth support is preferable to mucosal support because the compressibility of mucosa allows movement of the denture to occur. If there is no alternative to mucosal support the indirect retainer should cover a sufficiently wide area to spread the load and avoid mucosal injury
fINDIRECT RETAINER Class I RPD Usage
Ideally , a class I rpd has two indirect retainers as shown above; one for each
fINDIRECT RETAINER Class II RPD Usage
Indirect retainer rest seat; only one and on the side opposite the extension base Primary fulcrum line through most distal rest seats
Indirect retainer rest seat
Indirect retainer rest on tooth #28; only a secondary rest seat on the mesial of tooth #21 to support the lingual plate major connector
What is direct retainer?
Direct retainers are flexible parts of the casting that are designed to engage undercuts on the abutment teeth to resist removal of the prosthesis and to help prevent dislodgement. There are two basic types of direct retainers – infrabulge and suprabulge rertainers. This program describes how each of these types of retainers are employed in the RPI and RPA systems.
What is a retainer in dentistry?
Retainers, Clasp Assemblies and Indirect Retainers Direct retainers That component of a removable partial denture used to retain and prevent dislodgment of a clasp assembly or attachment .
What type of plate is used for bracing?
52. Types of Bracing In this patient most of the bracing is provided by the distal proximal plates. However the lingual plate supplements bracing to significant degree
What plate is used for reciprocation of retainers on the cuspid and the molar?
47. Reciprocation Reciprocation for the retainers on the cuspid and the molar in this unilateral case is accomplished with the proximal plates and lingual plate
What is the I bar contraindication?
17. “ I” Bar Retainers Contraindications Teeth with short clinical crowns Guide planes-proximal plates will be short and in this situation the “I” bar may not provide acceptable retention High frenum attachments will preclude proper positioning of the horizontal component Severely tilted abutments The “I” bar will project into the cheek. This is particularly problem with regard to 2 nd molars in the maxilla Lack of attached gingiva Buccal of mandibular 2 nd molars
Which plate is used for ciprocation of the I bar on the buccal surface of the molar?
43. Reciprocation Reciprocation of the “I” bar on the buccal surface of the molar is accomplished with the proximal plates
What forces displace the obturator portion of the prosthesis?
The forces of gravity tend to displace the obturator portion of the prosthesis, down and out of the defect. The indirect retainers resist this displacement. 34. Indirect Retainers – Myth or Reality The musculature of the lip tends to lift the prosthesis away from the tissue bearing surfaces in the anterior region.
