1
ICK Classification System for Partially Edentulous Arches

Sulieman S. Al-Johany, BDS, MSD,1 and Carl Andres, DDS, MSD2

1Assistant Professor, Department of Prosthetic Dental Sciences, College of Dentistry King Saud University Riyadh Saudi Arabia

2Professor and Director, Graduate Prosthodontics, Department of Restorative Dentistry Indiana University, School of Dentistry Indianapolis IN

Keywords

Classification system; dental implants; removable partial denture.

Correspondence

Sulieman S. Al-Johany, College of Dentistry, King Saud University, P.O. Box 60169, Riyadh 11545, Saudi Arabia. E-mail: saljohany@hotmail.com

Previously presented at the Table Clinic Session at the American College of Prosthodontists 2006 Annual Session, Miami, FL.

Accepted May 24, 2007

Published Journal of Prosthodontics August 2008; Vol. 17, Issue 6

doi: 10.1111/j.1532-849X.2008.00328.x

Abstract

Several methods of classification of partially edentulous arches have been proposed and are in use. The most familiar classifications are those originally proposed by Kennedy, Cummer, and Bailyn. None of these classification systems include implants, simply because most of them were proposed before implants became widely accepted. At this time, there is no classification system for partially edentulous arches incorporating implants placed or to be placed in the edentulous spaces for a removable partial denture (RPD). This article proposes a simple classification system for partially edentulous arches with implants based on the Kennedy classification system, with modification, to be used for RPDs. It incorporates the number and positions of implants placed or to be placed in the edentulous areas. A different name, Implant-Corrected Kennedy (ICK) Classification System, is given to the new classification system to be differentiated from other partially edentulous arch classification systems.

Partial edentulism is defined as the absence of some but not all the natural teeth in a dental arch.1 Several methods of classification of partially edentulous arches have been proposed and are in use. It has been estimated that there are over 65,000 possible combinations of teeth and edentulous spaces in opposing arches.2

The most familiar classifications are those originally proposed by Kennedy,3 Cummer,4 and Bailyn.5 Costa6 in 1974 summarized most of the classification systems for partially edentulous arches and the rationale of the classification. These included: (i) the number and position of direct retainers,4 (ii) the relation of edentulous spaces to abutment teeth,3 (iii) the type of denture support, that is, tooth-supported, tissue-supported, or a combination,5,7 (iv) the quality and degree of support a removable partial denture (RPD) receives from the abutment teeth and residual ridge,8 (v) the number, length, and position of edentulous spaces and the number and position of remaining teeth,9 (vi) the location and extent of edentulous spaces,10 (vii) the boundaries of the spaces,11 and (viii) combinations of these principles.3,12,13 Classifications have also been proposed by Neurohr,14 Austin and Lidge,15 Avant,16 and others.6,17 Kennedy's method of classification is probably the most widely accepted classification of partially edentulous arches today.2,17 None of these classification systems include implants, simply because most were proposed before implants became widely accepted. Recently, Misch and Judy18 described a classification system depending on the Applegate-Kennedy system, with emphasis on the available bone in the edentulous area for implant placement. Their classification involves four divisions: Divisions A and B when bone is available for implant placement, division C when bone is not available for implant placement, and division D, restricted to cases with severe atrophy of the edentulous area involving basal bone.

Implants with or without attachments can be used to improve the support, stability, and retention of an RPD. The esthetic result of the RPD can be greatly improved by the use of implant attachments, thus eliminating unesthetic clasps. With the use of implants, the options for RPD use have increased, and the high demands of many patients for esthetic prostheses have been satisfied.19-21

At this time, there is no classification system for partially edentulous arches incorporating implants placed or to be placed in the edentulous spaces for an RPD.

The purpose of this article is to present a simple classification system for partially edentulous arches with implants based on the Kennedy classification system, with modification, to be used for RPDs.

Kennedy Classification System

The Kennedy method of classification was originally proposed by Dr. Edward Kennedy in 1925.3 He divided all partially edentulous arches into four basic classes. Edentulous areas other than those determining the basic classes were designated as modification spaces.

1. Class I: Bilateral edentulous areas located posterior to the remaining natural teeth,
2. Class II: A unilateral edentulous area located posterior to the remaining natural teeth,
3. Class III: A unilateral edentulous area with natural teeth remaining both anterior and posterior to it, and
4. Class IV: A single, but bilateral (crossing the midline), edentulous area located anterior to the remaining natural teeth.

In 1954, Applegate12 provided eight rules governing the application of the Kennedy system and proposed a new classification named the Applegate-Kennedy classification system for partially edentulous situations. These rules can be summarized in three general principles.18 The first principle is that the classification should include only natural teeth involved in the definitive prostheses and follow rather than precede any extractions of teeth that might alter the original classification. The second principle is that the most posterior edentulous area always determines the classification. The third principle is that the edentulous areas other than those determining the classification are referred to as modifications and are designated by their number. The extent of modification is not considered, only the number of additional edentulous areas.

Guidelines for the new Classification System

The new classification system will follow the Kennedy method with the following guidelines:

1. No edentulous space will be included in the classification if it will be restored with an implant-supported fixed prosthesis.
2. To avoid confusion, the maxillary arch is drawn as half circle facing up and the mandibular arch as half circle facing down. The drawing will appear as if looking directly at the patient; the right and left quadrants are reversed.
3. The classification will always begin with the phrase "Implant-Corrected Kennedy (class)," followed by the description of the classification. It can be abbreviated as follows:
   1. ICK I, for Kennedy class I situations,
   2. ICK II, for Kennedy class II situations,
   3. ICK III, for Kennedy class III situations, and
   4. ICK IV, for Kennedy class IV situations.
4. The abbreviation "max" for maxillary and "man" for mandibular can precede the classification. The word modification can be abbreviated as "mod."
5. Roman numerals will be used for the classification, and Arabic numerals will be used for the number of modification spaces and implants.
6. The tooth number using the American Dental Association (ADA) system is used to give the number and exact position of the implant in the arch. (Note: other tooth numbering systems such as Fédération Dentaire Internationale [FDI] can be used, as can the tooth name. The ADA system was used by the authors because of familiarity).
7. The classification of any situation will be according to the following order: main classification first, then the number of modification spaces, followed by the number of implants in parentheses according to their position in the arch preceded by the number sign (#).
8. The classification can be used either after implant placement to describe any situation of RPD with implants, or before implant placement to indicate the number and position of future implants with an RPD.
9. A different name, ICK Classification System, is given to this classification system to be differentiated from other partially edentulous arch classification systems.

The Proposed ICK Classification System for Partially Edentulous Arches

Examples for Kennedy Class I Situations

For Kennedy class I situations, Figures 1.1-1.3 show the classification if no modification spaces exist. The full text can be used, or preferably the abbreviation (Fig 1.1).

Figure 1.1 Maxillary implant-corrected Kennedy class I (#2, 15) or ICK I (#2, 15).

If only one implant is placed in one of the two edentulous areas, it will be indicated between parentheses. This will mean that no implants were placed or to be placed in the other edentulous area (Fig 1.2).

Figure 1.2 ICK I (#2).

The main classification, followed by the number of modification spaces, will be placed first, followed by the position (number) of the implants in the edentulous areas in parenthesis arranged according to the tooth numbering system used.

The arrangement of the implants will be from right to left in the maxillary arch and from left to right in the...