A universal classification for removable partial denture situations

A UNIVERSAL

PARTIAL WXLLIAM

CLASSIFICATION FOR REMOVABLE DENTURE SITUATIONS

E. AVANT, A.B., B.S., D.D.S.”

Th.e Ohio State University,

College of Dentistry,

Columbus,

Ohio

T

HERE IS A NEED for a universal classification for removable partial denture situations. Applegatel wrote of the urgent need for such a system when writing or speaking of semidentulous conditions or their prosthetic corrections. Wilson2 wrote that a ,universally accepted classification of partial dentures is greatly needed. Boucher,3 commenting on Friedman’s proposed classification, wrote that an attempt should be: made to combine the good features of all classifications so that a universal classific:ation could be adopted. Several have been proposed, 4-10but the need for a universal classification still exists. REQUIREMENTS

OF A CLASSIFICATION

Any classification that attempts to give too much information, especially diagnostic and prognostic, seems destined for limited acceptance. Kennedy4 recognized this. His classification became the best known and is probably the most widely used today. Yet, it gives no more information than the cast of a partially edentulous dental arch. More recently, McCrackenil concluded that no single method of classification could be descriptive of any but the most basic types, and that a basic classification should be sufficient. A classification should enable one to : ( 1) visualize the type of partially edentulcus arch represented, (2) differentiate between potential tooth-borne and extensionbase partial dentures, (3) get a general idea of the type of design to be used, and (4) know the general location of the teeth being replaced. A classification that offers this information meets the basic requirements. But to be useful and to be accepted, a classification must give this information in the most simple, logical, and vivid manner. Toward that goal, I suggest the following classification. BASIS FOR PROPOSED CLASSIFICATION

Anatomically, the dental arch is composed of three segments or groups of teeth : two posterior separated by a third, the anterior (Fig. 1) . This natural, not arbitrary, division is an excellent basis for a classification. *Graduate Student in Prosthodontics. Formerly Instructor, Department tlnodontics, Dental School, University of Maryland, Baltimore, Md. 533

of Removable

Pros-

534

Fig. l.-The anatomic by the anterior segment.

J. Pros. Den. May.June. 1966

AVANT

division

of the dental

arch into

two posterior

segments

separated

THE CLASSIFICATION

Five classes make up the classification, which applies to removable partial dentures or to partially edentulous arches. The definitions given are for partial dentures. Class I.-This replaces one or more posterior teeth on one side of the arch, mesial to the most distal abutment tooth (Fig. 2). Class I-F.-This replaces one or more posterior teeth on one side of the arch, terminating in a free end (Fig. 3). Class II.-This replaces one or more posterior teeth on both sides of the arch, mesial to the most distal abutment tooth on both sides (Fig. 4). Class II-F.-This replaces one or more posterior teeth on both sides of the arch, terminating in free ends on both sides (Fig. 5). Clars III.-This replaces one or more anterior teeth (Fig. 6). Basically, changing the verb form “replaces” to “to be replaced” alters any of the above definitions to fit the partially edentulous arch. For example, a Class III partially edentulous arch has one or more anterior teeth to be replaced. I find it difficult to place much importance on whether a classification is for the partially edentulous arch or for the partial denture. A Class I partial denture must be constructed on a cast made from an impression of a Class I arch. The same is true for any class. It is logical, then, to say that the class does not change in going from the arch to the cast to the partial denture, or vice versa. The cast may be the best link in the chain to demonstrate the class of a given situation. Moreover, the need to classify a partially edentulous arch does not exist unless a removable partial denture is concerned. RULE FOR CLASSIFYING

To classify a removable partial denture situation, assign it to the class that covers best the mast inzportant segwzent(s) being restored. If there are any remaining spaces being restored, use minor notations to indicate them by adding the small

Fig. 2. (upper Fig. 3 (upper Fig. 4 (middle Fig. 5 (middle Fig. 6 (lower Fig. 7 (lower Class I-F-a.

left).-A Class I partial denture situation. right) .-A Class I-F partial denture situation. left).-A Class II partial denture situation. right) .-A Class II-F partial denture situation. left).-A Class III partial denture situation. right) .-A Class I-F situation with anterior teeth being replaced

also, hence

letter “a” for space(s) in the anterior segment and “p” for space(s) in each pastserior segment. MINOR

NOTATIONS

The minor notations, “a” and “p”, are used to indicate spaces that remain a.fter a basic class has designated the most important areas being restored. A basic c:lass covering all spaces in every arch would be too complicated or cumbersome.

536

AVANT

J. Pros. Den. May-June, 1966

Fig. 8 (upper left).-A Class I-F situation with posterior teeth on the opposite side being replaced also, hence Class I-F-p. Fig. 9 (upper right).-A Class I-F situation with teeth being replaced in both the anterior segment and the opposite posterior segment also, hence Class I-Fap. Fig. 10 (middle left).-A Class III situation with a tooth being replaced in one posterior segment also, hence Class III-p. Fig. 11 (middle right).-A Class III situation with a tooth being replaced in both posterior segments also, hence Class III-pp. Fig. 12 (lower left).-A Class I situation with anterior teeth being replaced also, hence Class I-a. Fig. 13 (lower right).-A Class II situation with anterior teeth being replaced also, hence Class II-a.

Fig. 14 (upper left).-A Class II-F situation with anterior teeth being replaced also, hence Class II-F-a. Fig. I5 (upper right).-A Class I situation, but the left canine is in the anterior segment and should be so indicated although it is in the same edentulous space, hence Class I-a. Note that the right second molar is not being replaced and is not indicated. Fig. 16 (middle left).-A Class III situation, but the right first premolar is in the posterior segment and should be indicated with a “p” although it is in the same edentulous space, hence Class III-p. Note that the missing left second premolar is not indicated since it is not being replaced. Fig. 17 (middle right).-A Class III situation. Since both edentulous spaces being restored are in the anterior segment, no minor notations are needed. Note that the missing right second molar is not being replaced and does not influence the classification. Fig. 18 (lower left).-A cl,ass II-F situation. The space for the missing left first premolar is included in the basic class: therefore the only minor notation needed is for the anterior space, hence Class II-F-a. Fig. 19 (lower right).-A Class III situation because the most important segment being restored is the anterior. Both posterior segments are involved and each is indicated by a “p”. hence Class III-pp. If the two posterior segments were considered more important to restore, then this would be. a Class II situation and the anterior segment would be indicated with a minor notation.

538

AVANT

J. Pros. Den. May-June, 1966

Three minor notations are possible in Class I-F situations (Figs. 7, 8, and 9). One can indicate the anterior segment (Class I-F-a), the opposite posterior segment (Class I-F-p), or both of these segments (Class I-F-ap) . Class III can have one or both posterior segments indicated (Figs. 10 and 11). Thus, Class III-p and Class III-pp are possible. Only the anterior segment can be indicated by a minor notation in Class I, Class II, and Class II-F situations (Figs. 12, 13, and 14). Both posterior segments are designated by the class itself in Class II and Class II-F, and there can be no Class I-p since that is Class II by definition. Figs. 15 to 19 demonstrate the use of minor notations. Note that any edentulous space not being restored influences neither the class nor the minor notation. Also, each segment having any edentulous space being restored but not designated by the basic class is indicated by a minor notation, but only once, although more than one such space may be present in the segment. When speaking of partial denture situations, it may be better to omit the minor notations even if indicated, and use only the name of the basic class. However, when one wishes to be more descriptive, such as when writing or keeping records, the minor notations can be most effective. SIMPLIFiCATION

Each name of the five classes all but tells what is seen. Consider the following: Class I-F is cme free-end posterior segment. Class II-F is tzero free-end posterior segments. Class I is one posterior segment without a free end, and Class II is ~ZM posterior segments without free ends. These four classes cover the posterior segments. Remembering that the dental arch is composed of two posterior segments separated by a third segment, the anterior, gives meaning to Class III. An extension base is defined as a unit of a removable prosthesis that extends anteriorly or posteriorly, terminating in a free end.12 The letter “F” conveys this idea of a free end and helps the dentist visualize what is present in Class I-F and Class II-F situations. The idea of minor notations is also in keeping with simplicity. The snzdl letters “a” and “p” indicate less important areas being restored. SUMMARY

The need for a universal classification for removable partial denture situations is cited, and the basic requirements are stated. A classification based on the anterior and posterior segments of the dental arch is suggested. REFERENCES

1. Applegate, Oliver C.: Essentials of Removable Partial Denture Prosthesis, ed. 3, Philadelphia, 1965, W. B. Saunders Company, p. 9. 2. Wilson, John H. : Partial Dentures, Sydney, 1955, Angus & Robertson, p. 77. 3. Boucher, Carl 0. : Through the Eyes of the Editor, J. PROS. DENT. 3:445, 1953. 4. Kennedy, Edward: Partial Denture Construction, Brooklyn, 1928, Dental Items of Interest Publishing Company, pp. 3-8. 5. Cummer,. W. E.: Partial Denture Service, in Turner, Charles E., and Anthony! L. P., editors: The American Textbook of Prosthetic Dentistry, ed. 5, Philadelphia, 1928, Lea & Febiger, Publishers, pp. 353-356.

Volume 16 iS umber 3

CLASSIFICATION

6. Beckett, 7. 8. 9. 10. 11. 12.

FOR PARTIAL

DENTURES

539

Leonard S.: The Influence of Saddle Classification on the Design of Partial Removable Restorations, J. PROS. DENT. 3:506-516, 1953. Friedman, Joel: The ABC Classification of Partial Denture Segments, J. PROS. DENT. 3:517-524, 1953. Swenson, Merrill G., and Terkla, Louis G.: Partial Dentures, St. Louis, 1955, The C. V. Mosby Company, pp. 223-229. Applegate, Oliver C.: Essentials of Removable Partial Denture Prosthesis, ed. 2, Philadelphia:, 1959, W. B. Saunders Company, pp. 9-23. Skinner! C.. N.: A Classification of Removable Partial Dentures Based Upon the Principles of Anatomy and Physiology, J. PROS. DENT. 9:240-246, 1959. McCracken, William L.: Partial Denture Construction, ed. 2, St. Louis, 1964, The C. V. Mosby Company, p. 73. Roucher, Carl O., editor: Current Clinical Dental Terminology, St. Louis, 1963, The C. V. Mosby Company, p. 39. 305 WEST 12~~ AVE. COLUMBUS, OHIO 43210