WHAT ARE THE DIFFERENT CLASSIFICATIONS OF REMOVABLE PARTIAL DENTURES?
As dentists we always do our best to provide the best treatment to our patients base on our diagnosis, patient's medical and dental history, preferences and affordability. Thus, there are several options available to us every time we do our treatment plan and make the decision with our patient's consent.
The ability of humans trying to replace their missing teeth has been in existence since 700 BC with the use of human or animal teeth and up until 1700 the use of ivory was the chosen material. It was in 1770 that the first porcelain dentures were introduced. At that time, they were prone to chipping and appeared to be too white to be aesthetically good, thus, most people still preferred human or even animal teeth. It was in the 1850s that dentures began and made of Vulcanite, a form of hardened rubber into which porcelain teeth were set. Following the turn of the 20th century, acrylic resin and other plastics were introduced.
With development of dental science and materials, we have gone a long way from 700 BC and removable partial dentures for so many years has provided us one of the most affordable and least destructive appliance for missing tooth replacement. However, it can potentially give significant negative impact on oral sensory input during function, as well as on the prosthetic bulk required. Because of this, removable partial dentures maybe a challenge to patient's oral comfort and convenience, so, patients should be made aware of this during the treatment planning stage. Due to these factors, it is vital for us dentists to really remember, know and understand the basic classifications and designs of constructing RPDs. These are significant information, so, we can choose the right material and design if our treatment plan in replacing our patient's teeth will be removable partial denture. DMD cEnter provides you a short review of them on this post.
I. Classification of Partial Endentulous Based on Support
There are 2 types of partially edentulous arches based on the tissues which provide support. Support is the resistance to movement on the denture towards the edentulous ridge. It is also the transference of occlusal stress to the surrounding oral structures.
This is considered a simple classification system that’s very ideal because the principles of RPD design depends to a great extent on its supporting tissue.
A. The Tooth Supported RPD
Tooth supported RPD receive all their support from the abutment teeth. The direct retainers on the abutment teeth provided its retentiveness while strengthening the contact rigid components of the framework with natural teeth. Most tooth supported RPDs have a cast metal major connector. Tooth supported RPDs do not move in function.
B. The Mucosa Supported RPD
Tissue supported RPDs are primarily supported by the tissues (mucosa overlying bone) of the denture foundation area. They may obtain some tooth support by contact of the denture above the height of contour of the natural teeth.
Mucosa supported RPDs usually have acrylic major connectors and usually interim RPDs. These types of support will move in function because of the resiliency of the mucosa. Retention for tissue supported RPDs is customarily provided by wrought wire retentive clasp arms on selected natural teeth, the contact of the acrylic denture below the height of contour of the natural teeth, and by those factors which provide retention of complete dentures, i.e gravity (for mandibular RPDs), interfacial surface tension, neuromuscular control, etc. Bracing can be provided by contact of the denture bearing tissues, the natural teeth, supplemented by contact of the tongue, checks and lips
In a nutshell, we can say that the mucosa supported RPD is a complete denture with some remaining natural teeth. Tissue supported RPDs have the potential to cause soft tissue damage, alveolar bone deformity and periodontal attachment loss. It is suggested that these types of dentures should be used for only a short period of time (one year or less) while a FPD, definitive RPD or implant prosthesis is constructed.
II. Classification of Removable Partial Prosthesis Based on Arch Orientation
The most widely accepted system of classification of RPDs and partially edentulous arches was proposed by Dr.Edward Kennedy in 1923. It is based on the configuration of the edentulous spaces and remaining natural teeth.
The value of the Kennedy Applegate- classification system is that it is relatively simple, easy to remember, extremely comprehensive and very practical which permits a close visualization of the partially edentulous arch or RPD. This gives a full overview of the arch that help in deciding which designed for that case.
It indicates the type of support for the RPD, which suggest certain physiologic and mechanical principles of treatment and RPD design. There is a correlation between the basic classes and the incidence of the partially edentulous arch configurations. It allows quick identification of the partially edentulous arches, which are difficult to treat and simplifies communication with the lab technician.
Kennedy Classification for Partially Edentulous
➢ Class I (Cl I): Bilateral edentulous areas located posterior to the remaining natural teeth.
➢ Class II (Cl II): Unilateral edentulous area located posterior to the remaining natural teeth.
➢ Class III (Cl III): Unilateral edentulous area with natural teeth both anterior and posterior to it.
➢ Class IV (Cl IV): Single, bilateral edentulous area located anterior to the remaining natural teeth.
➢ Class V (Cl V): A unilateral tooth bounded edentulous area where the anterior tooth is weak and incapable of providing support as an abutment
➢ Class VI (Cl VI): An edentulous situation where the bounded teeth are capable of total support of the prosthesis
Applegate and Swenson and Terkla have suggested rules to apply to the Kennedy Classification System to eliminate some uncertainties and to make the classification more descriptive. These 8 rules help in classifying the partially edentulous arch, thus, modification in Kennedy’s Classification.
They are 8 rules to govern the application of the Kennedy system:
➢ Rule 1: Classification should follow rather than precede extractions that might alter the original classification.
➢ Rule 2: If the third molar is missing and not to be replaced it is not considered in the classification.
➢ Rule 3: If the third molar is present and is to be used as an abutment, it is considered in the classification.
➢ Rule 4: If the second molar is missing not to be replaced that is the opposing second molar is also missing and is not considered in the classification.
➢ Rule 5: The most posterior edentulous area or areas always determines the classification.
➢ Rule 6: Edentulous areas other than those determining the classification are referred to as the modification spaces and are designated by their number. Referred to as mod. (ex: mod 1, mod 2...etc.)
➢ Rule 7: The extent of the modification is not considered, only the number of additional edentulous areas.
➢ Rule 8: There can be no modification areas in class IV arches. Because any edentulous area lying posterior to the single bilateral area determines the Classification
In conclusion, by familiarizing ourselves with these classifications, we are able to provide a good treatment plan. It gives us a better advantage in visualizing the extent of the denture we are designing. We are able to consider the mucosa and oral structure present for each individual patient so we can anticipate the difficulties commonly to occur for that particular design. In this way we are able to communicate our plan to our technicians, ensuring that our design provides comfort and function to our patient.
Dr. Bryan Anduiza - Writer
Dr. Mary Jean Villanueva - Editor
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