A removable partial denture (RPD) is an artificial tooth for partially edentulous patients who wish to have a replacement tooth for functional or aesthetic reasons and who can not have bridges (partial permanent denture) for any reason, such as lack of teeth needed to serve as support for bridges (ie distal buffers) or financial limitations.
This type of prosthesis is referred to as a partial release of the denture because the patient can lift and reinsert it when needed without professional help. Conversely, "fixed" prosthesis can and should be removed only by professional dentists.
Video Removable partial denture
Partially edentulous condition
Depending on the location of the missing tooth, the edentulous situation can be grouped into four distinct categories, as defined by Dr. Edward Kennedy in the classification of the arch is partly not edentulous.
- Class I (bilateral free ended part edentulous)
- Class II (unilateral free ends partly edentulous)
- Class III (unilateral partially limited edentulous)
- Class IV (bilaterally bounded anterior edentulous portion)
Kennedy Class I RPD is made for people who lose some or all of their posterior teeth on both sides (left and right) in one arch ( either mandibular or maxillary), and no posterior tooth to the edentulous region. In other words, the Class I RPD touches a tooth that is more directed to the front of the mouth, while replacing the lost posterior tooth on both sides with a false tooth. Artificial teeth consist of plastic or porcelain.
Class II RPD is made for people who lose some or all of their posterior teeth on one side (left or right) in a single arch, and no teeth behind the edentulous area. Thus, the Class II RPD grasps more teeth toward the front of the mouth, as well as on the more teeth toward the back of the non-missing sides of the mouth, while replacing the more missing ones- mouth-to-mouth on one side with a fake denture.
Class III RPD is made for people who lose multiple teeth in such a way that the edentulous region has the remaining teeth both posterior and anterior. Unlike Class I and Class II RPD that are both dental-and-tissue-borne (meaning they both hold onto the teeth, as well as rest in posterior edentulous areas for support), Class III RPD is tightly gear-borne, meaning they are only attached on the teeth and no need to rest on the network for additional support. This makes the Class III RPD much safer according to the three removable proteson rules that will be mentioned later: support, stability and retention. (See article on dentures for a more thorough review of these three released prosthodontic bases.)
However, if the edentulous region described in the preceding paragraph crosses the anterior midline (ie, at least two missing central incisors), RPD is classified as Class IV Class IV RPD . By definition, the design of the Kennedy Class IV RPD will only have one edentulous area.
Class I, II and III RPDs that have some edentulous regions in which the replacement gear is placed are further classified by the modified state defined by Oliver C. Applegate. The Kennedy classification is governed by the most posterior editional areas being restored. So if, for example, the upper jaw arch is missing the # 1, 3, 7-10 and 16 teeth, the RPD will become Kennedy Class III mod 1. It will not be Class I, since the missing third molar teeth are generally not returned in RPD (though if they were, the classification would indeed be Class I), and it would not be Class IV, since the modification room is not allowed for Kennedy Class IV.
The results of research conducted in Saudi Arabia, showed that the incidence of parental Kennedy Class III edenulisme is 67.2% in the arch of the upper jaw and 64.1% in the mandible arch. Followed by Class II in both the maxillary and mandibular arches with an average of 16.3% in the maxillary arch and 14.8% in the mandible arch. Based on these results, Class III had the highest prevalence in the younger patient group (31-40 years). Class I and class II had the highest incidence among the older group of patients (41-50 years).
Maps Removable partial denture
RPD components
Instead of lying completely on the ridge like complete dentures, partially removed partial teeth have cobalt-chrome or titanium metal or plastic clamps "pinch" onto remaining teeth, making the RPD more stable and stronger.
The parts of the RPD can be listed as follows (and exemplified by the image above):
- Main connector (The thick metal "U" in the above RPD image is the lingual blade , of a type of major connector)
- Posterior anterior palatal strap
- Single palatal strap
- U-shaped palatal connector (horseshoe)
- Linguistic bar
- Plat linguistics
- Small connector (See the small struts protruding from the lingual bar at a 90 degree angle.)
- Direct picking (An example is on the upper left and lower right corner of the bottom photo: the clip arm acts to hold the teeth and keep the RPD in place.A metal handle and immediately rest near the denture also is a direct retainer.)
- Indirect Retainer (An example is a small piece of metal that comes out of the letter "U" at an angle of 90 degrees near the top of the top photo, which is a cingulum resting on a canine.)
- Physical retainer (This is a metal mesh that allows pink base material to connect to an RPD metal frame.) Some consider the physical followers of their own components (making a total of seven), while others consider it in the indirect retainer category (thus making a total of six components.)
- Basic (pink material, imitating gingiva)
- Teeth (plastic or porcelain formed in the form of a tooth)
Design buckle
Direct followers can come in a variety of designs:
- The circular petal bundle (suprabulge)
- Akers'
- Half and half
- Action back
- Ring buckle
- Wire-holder wire
- Roach buckle (infrabulge)
- I-bar
- T-bar
- Y-bar
- 7-bar
Both the circumferential cast and the wire-clip clamp are the supra protrusions, because they perform the teeth of the teeth by forming coronal to contour height, while the Roach clamp is infrabulge clasps and performs the undercuts of the gingiva.
In addition there are several specific theories that include the design of the clasp:
- RPI : mesial break, distolingual guide plate, I-bar
- The RPI design is built to grasp bilateral free end extensions. This clasps is unique because they have to consider extra torque strength due to being a covered network (and not a covered tooth) in the posterior.
- Explained by Kratochvil in 1963 and modified by Krol in 1973
- Kratochvil designs a buffer with long breaks (from the mesial marginal ridge to the distal hole), long guiding aircraft, and ordinary I-bar clips.
- The chips modify this design with short occlusal breaks, short guides (touch only from occlusal to middle third), and I-bar shift mesial. The theory behind Krol's decision is to allow partial denture movements without placing too much torque on the supporting tooth.
- Illustration of RPI design function
- RPA : mesial break, distolingual guide plate, Akers' style buckle lifting arm
- RPC : mesial break, distolingual guide plate, another type of circular cast buckle
- So named in answer to RPI Philosophy introduced by Kratochvil and Kroll
References
Source of the article : Wikipedia
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