Rests (Stewart) are the components of RPD that serve primarily to transfer forces occurring against the long axis of the abutment teeth. McCracken Any unit of a partial denture that rests on a tooth surface to provide vertical support is called a rest.
What is the difference between rest preparation and rest rest?
REST is any rigid part of an RPDframework which contacts a properlyprepared surface of a tooth. REST PREPARATION or RESTSEAT is any portion of a tooth or restorationproperly prepared to receive a rest.
What is the purpose of the rest on a prosthesis?
11. In addition to transferring forces, each rest should serve as a vertical stop for the prosthesis. Firm, positive contact between a rest and rest seat minimizes vertical displacement of the prosthesis and prevents injury to the soft tissues. 12. The primary purpose of the rest is to provide vertical support for the partial denture.
Should the RPI design be used when designing a distal rest?
Therefore the RPI design be used wherever possible. However, an I-bar cannot be used routinely due to the fact that a tissue undercut frequently exists in the region of the abutment. A distal rest concept has drawbacks if designed incorrectly.
Should I plan my RPD before other treatments?
PLAN THE RPD BEFORE BEGINNING ANY OTHER TREATMENT • Survey, tripod, heights of contour • Draw design on surveyed cast •Design approvedbefore any treatment started: o Affects direct restorations o Can influence need for/preparations for crowns o Insures RPD can be completed successfully o NO EXCEPTIONS CLINICAL STEPS
What are the functions of a rest on a partial denture?
What is the function of a rest on a partial denture? It prevents the partial denture from moving in a gingival direction, it aids in distributing the retention load to several teeth, and it prevents food from getting between the abutment tooth and the retainer.
Where do rests go on RPD?
1:182:4706 Occlusal Rest Seats - YouTubeYouTubeStart of suggested clipEnd of suggested clipTo create the wider base of the triangular rest seat. This is necessary for bulk to ensure that theMoreTo create the wider base of the triangular rest seat. This is necessary for bulk to ensure that the metal rest has sufficient strength to prevent fracture where it joins the minor connector. Remember
What is occlusal rest seat?
Definitions occlusal rest and rest seat. 2. Rest preparation or rest seat: - Is any portion of a tooth or restoration properly. prepared to receive a rest. Provide vertical support for the partial denture.
What are the components of RPD?
The four basic components involved in an RPD are the artificial teeth, the denture base, retainers, and connectors (Figure 3.17).
How deep should rest seats be?
3- 1.5mm deep1- The rest seat is prepared in the form of a rounded notch located on the incisal edge of anterior teeth an incisal rest seat is usually placed on the mesio- or disto-incisal angle of the incisor teeth with the deepest portion towards the center of the tooth. 2- 2.5mm the mesiodistal width of the tooth. 3- 1.5mm deep.
Where do you put rest seats?
Rests should always be located on properly prepared tooth surfaces. The prepared surface of an abutment to receive the rest is called the rest seat. Rests are designated by the surface of the tooth prepared to receive them (occlusal rest, lingual rest, and incisal rest).
What is stress breaker in RPD?
❑ A stress breaker is something like a hinge joint placed within the. denture framework, which allows the two parts of the framework. on either side of the joint to move freely. ( Mc Cracken)
What is RPI in dentistry?
RPI System = Occlusal Rest, distal Guide Plane, Gingivally approaching I bar. Used to prevent distal movement/tipping of abutment tooth to a free end saddle. Allows the free saddle to rotate slightly without damaging the soft tissues or abutment tooth.
What is a pier abutment in RPD?
Pier abutment is an intermediate abutment for a fixed dental prosthesis. Moreover, an intermediate abutment is a natural tooth located between terminal abutments that serve to support a fixed/removable prosthesis.
What is stress breaker in RPD?
❑ A stress breaker is something like a hinge joint placed within the. denture framework, which allows the two parts of the framework. on either side of the joint to move freely. ( Mc Cracken)
What is RPI in dentistry?
RPI System = Occlusal Rest, distal Guide Plane, Gingivally approaching I bar. Used to prevent distal movement/tipping of abutment tooth to a free end saddle. Allows the free saddle to rotate slightly without damaging the soft tissues or abutment tooth.
What is reciprocation in a denture?
13 — Reciprocation. (1) A clasp is effective in retention from its position when the denture is fully seated to where it escapes over the bulbosity of the tooth. This vertical measurement may be termed the 'retention distance'.
6: Rests and Rest Seats
The capacity for teeth to resist functional forces and remain stable over time is provided through their sophisticated support mechanisms. Studies have shown that displacement and recovery following loading are far better for natural teeth than for oral mucosa.
Role of Rests in Control of Prosthesis Movement
Appropriate use of teeth requires consideration as to how best to engage teeth for the supportive qualities they provide. Because the most effective resistance can be provided if the tooth is stressed along its long axis, the prosthesis framework should engage the tooth in a manner that encourages axial loading.
Form of the Occlusal Rest and Rest Seat
1. The outline form of an occlusal rest seat should be a rounded triangular shape with the apex toward the center of the occlusal surface ( Figure 6-2 ).
Extended Occlusal Rest
In Kennedy Class II, modification 1, and Kennedy Class III situations in which the most posterior abutment is a mesially tipped molar, an extended occlusal rest should be designed and prepared to minimize further tipping of the abutment and to ensure that the forces are directed down the long axis of the abutment.
What is rest seat?
2. Rest:Rest: extensions of a Partial Denture, Placed in Rest Seats, Which are prepared on either the Occlusal, Lingual surfaces or Incisal edges of the teeth, providing Support to the Partial Denture. 3. Rest seat:Rest seat: portion of a tooth prepared to receive a rest. 4.
What are the requirements for an occlusal rest?
Requirements of occlusal RestRequirements of occlusal Rest:: 1.Should have sufficient thickness of metal to prevent breakage especially over the marginal ridge. 2.It should fit the rest seat accurately with beveled margins, preventing food stagnation or impaction.
Where are rests placed on a saddle?
Rests are usually placed on the tooth surface nearest the saddle on either side. Mesially if part of an RPI system - which is the furthest side of the tooth from the saddle. They can be incorporated into crowns of abutment teeth if planned correctly.
Which ridge can be taken advantage of?
Maxilla – palate and alveolar ridge can be taken advantage of
Which retention moves the fulcrum of movement?
Providing indirect retention moves the fulcrum of movement.
Can lower canine rest seats be made with composite?
Lower canines rest seats may be built with composite – without disturbing the occlusion.
What is an auxiliary rest?
24. Auxiliary or secondary rests are used as indirect retainers in extension base removable partial dentures (Class I, Class II, and long-span Class IV applications). 25. Three major forms of rests are: 1. Occlusal rests — so named because they are seated on the occlusal surfaces of posterior teeth.
Where should the occlusal rest be located?
39. The deepest portion of an occlusal rest should be located near the center of the mesial or distal fossa. From this point, the rest seat should rise gently toward the marginal ridge. 40. An occlusal rest should be at least 0.5 mm thick at its thinnest point and 1.0 to 1.5 mm thick where it crosses the marginal ridge.
What is a lingual rest?
Lingual or cingulum rests and rest seats. 42. Lingual or cingulum rests are used primarily on maxillary canines. The normal morphology of a maxillary canine permits preparation of a satisfactory rest seat with minimal tooth reduction.
What is an occlusal rest?
An OCCLUSAL REST: - Transfers stress to the abutment tooth - Resists movement of the prosthesis in a cervical direction -Stabilizes the retentive arm in the proper position Avoid placing the rest in Glass Ionomer – and choose composite over amalgam for Class II situations.
Where is a small round bur rest seat placed?
A small round bur type rest seat placed in the mesial or distal lingual cingulum area cervical to any opposing occlusal contact. When placing, care is taken not to undercut the axial wall area to the path of placement of the rpd.
How far from the FGM does the posterior border of a complete palatatal plate end?
COMPLETE PALATAL PLATE MODIFIED PALATAL PLATE Anterior border ends in valley of rugae not less than 6mm from fgm Posterior border must not impinge upon movable tissue
What angle is needed to make a rest seat positive?
Less than 90 degree angle to make rest seat “positive” Marginal ridge lowered to allow sufficient thickness without creating an occlusal interference. Deepest portion of rest seat; deeper than reduced marginal ridge area
What is a RPD?
2. Removable partial denture(RPD): A partial denture that can be removed and replaced in the mouth by the patient.
What is the term for the component of a partial denture that provides both retention and support for the partial denture?
Stability: Resistance to movement in a horizontal direction (anterior-posteriorly or medio-laterally 6. Support: Resistance to movement towards the tissues or teeth 7. Abutment: A tooth that supports a partial denture. 8. Retainer: A component of a partial denture that provides both retention and support for the partial denture
