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A UNIVERSAL CLASSIFICATION FOR REMOVABLEPARTIAL DENTURE SITUATIONSWXLLIAM 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 denturesituations.Applegatel wrote of the urgent need for such a system when writing or speak-

ing of semidentulous conditions or their prosthetic corrections. Wilson2 wrote thata ,universally accepted classification of partial dentures is greatly needed. Boucher,3commenting on Friedmans proposed classification, wrote that an attempt shouldbe: made to combine the good features of all classifications so that a universal classi-fic:ation could be adopted.

Several have been proposed, 4-10but the need for a universal classification stillexists.REQUIREMENTS OF A CLASSIFICATION

Any classification that attempts to give too much information, especially diag-nostic and prognostic, seems destined for limited acceptance. Kennedy4 recognizedthis. His classification became the best known and is probably the most widely usedtoday. Yet, it gives no more information than the cast of a partially edentulousdental arch. More recently, McCrackenil concluded that no single method ofclassification could be descriptive of any but the most basic types, and that a basicclassification should be sufficient.

A classification should enable one to : ( 1) visualize the type of partially edentu-lcus arch represented, (2) differentiate between potential tooth-borne and extension-base 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 offersthis 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 vividmanner. Toward that goal, I suggest the following classification.BASIS FOR PROPOSED CLASSIFICATION

Anatomically, the dental arch is composed of three segments or groups ofteeth : two posterior separated by a third, the anterior (Fig. 1) . This natural, notarbitrary, division is an excellent basis for a classification.

*Graduate Student in Prosthodontics. Formerly Instructor, Department of Removable Pros-tlnodontics, Dental School, University of Maryland, Baltimore, Md.533

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534 AVANT J. Pros. Den.May.June. 1966

Fig. l.-The anatomic division of the dental arch into two posterior segments separatedby the anterior segment.THE CLASSIFICATION

Five classes make up the classification, which applies to removable partialdentures or to partially edentulous arches. The definitions given are for partialdentures.

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 ClassIII partially edentulous arch has one or more anterior teeth to be replaced. I findit difficult to place much importance on whether a classification is for the partiallyedentulous arch or for the partial denture. A Class I partial denture must be con-structed on a cast made from an impression of a Class I arch. The same is true forany class. It is logical, then, to say that the class does not change in going from thearch to the cast to the partial denture, or vice versa. The cast may be the best linkin the chain to demonstrate the class of a given situation. Moreover, the need toclassify a partially edentulous arch does not exist unless a removable partial dentureis concerned.RULE FOR CLASSIFYING

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

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Fig. 2. (upper left).-A Class I partial denture situation.Fig. 3 (upper right) .-A Class I-F partial denture situation.Fig. 4 (middle left).-A Class II partial denture situation.Fig. 5 (middle right) .-A Class II-F partial denture situation.Fig. 6 (lower left).-A Class III partial denture s ituation.Fig. 7 (lower right) .-A Class I-F situation with anterior teeth being replaced also, henceClass I-F-a.

letter a for space(s) in the anterior segment and p for space(s) in each pas-tserior segment.MINOR NOTATIONS

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

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536 AVANT J. Pros. Den.May-June, 1966

Fig. 8 (upper left).-A Class I-F situation with posterior teeth on the opposite side beingreplaced also, hence Class I-F-p.Fig. 9 (upper right).-A Class I-F situation with teeth being replaced in both the anteriorsegment 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 posteriorsegment also, hence Class III-p.Fig. 11 (middle right).-A Class III situation with a tooth being replaced in both posteriorsegments also, hence Class III-pp.Fig. 12 (lower left).-A Class I situation with anterior teeth being replaced also, henceClass I-a.Fig. 13 (lower right).-A Class II situation with anterior teeth being replaced also, henceClass II-a.

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Fig. 14 (upper left).-A Class II-F situation with anterior teeth being replaced also, henceClass II-F-a.Fig. I5 (upper right).-A Class I situation, but the left canine is in the anterior segmentand should be so indicated although it is in the same edentulous space, hence Class I-a. Notethat 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 posteriorsegment and should be indicated with a p although it is in the same edentulous space, henceClass III-p. Note that the missing left second premolar is not indicated since it is not beingreplaced.Fig. 17 (middle right).-A Class III situation. Since both edentulous spaces being restoredare in the anterior segment, no minor notations are needed. Note that the missing right secondmolar 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 premolaris included in the basic class: therefore the only minor notation needed is for the anteriorspace, hence Class II-F-a.Fig. 19 (lower right).-A Class III situation because the most important segment beingrestored 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 aminor notation.

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538 AVANT J. Pros. Den.May-June, 1966Three 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 seg-ment (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 segmentsare designated by the class itself in Class II and Class II-F, and there can be noClass I-p since that is Class II by definition.

Figs. 15 to 19 demonstrate the use of minor notations. Note that any edentulousspace not being restored influences neither the class nor the minor notation. Also,each segment having any edentulous space being restored but not designated by thebasic class is indicated by a minor notation, but only once, although more than onesuch space may be present in the segment.When speaking of partial denture situations, it may be better to omit the minornotations even if indicated, and use only the name of the basic class. However, whenone wishes to be more descriptive, such as when writing or keeping records, theminor 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 posteriorsegments. Class I is one posterior segment without a free end, and Class II is ~ZMposterior segments without free ends. These four classes cover the posterior seg-ments. Remembering that the dental arch is composed of two posterior segmentsseparated by a third segment, the anterior, gives meaning to Class III.

An extension base is defined as a unit of a removable prosthesis that extendsanteriorly or posteriorly, terminating in a free end.12 The letter F conveys thisidea of a free end and helps the dentist visualize what is present in Class I-F andClass II-F situations.The idea of minor notations is also in keeping with simplicity. The snzdlletters a and p indicate less important areas being restored.SUMMARY

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

1. Applegate, Oliver C.: Essentials of Removable Partial Denture Prosthesis, ed. 3, Philadel-phia, 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 In-terest 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.

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Volume 16iS umber 3 CLASSIFICATION FOR PARTIAL DENTURES 5396. Beckett, Leonard S.: The Influence of Saddle Classification on the Design of PartialRemovable Restorations, J. PROS. DENT. 3:506-516, 1953.7. Friedman, Joel: The ABC Classification of Partial Denture Segments, J. PROS. DENT.3:517-524, 1953.8. Swenson, Merrill G., and Terkla, Louis G.: Partial Dentures, St. Louis, 1955, The C. V.Mosby Company, pp. 223-229.9. Applegate, Oliver C.: Essentials of Removable Partial Denture Prosthesis, ed. 2, Philadel-phia:, 1959, W. B. Saunders Company, pp. 9-23.10. Skinner! C.. N.: A Classification of Removable Partial Dentures Based Upon the Prin-ciples of Anatomy and Physiology, J. PROS. DENT. 9:240-246, 1959.11. McCracken, William L.: Partial Denture Construction, ed. 2, St. Louis, 1964, The C. V.Mosby Company, p. 73.12. 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