Sakurai et al.

Int Chin J Dent 2006; 6: 93-95.

A classification for complete overdenture based on location ofcanine coping
Hiroshi Sakurai, DDS,a Keii Shou, DDS,a Tomohiko Ishigami, DDS, PhD,a,b Naoki
Tsukimura, DDS, PhD,a,b and Tetsuo Ohyama, DDS, PhDa,bab

Department of Partial Denture Prosthodontics, and Division of Oral and Cranio- maxillofacial
Research, Dental Research Center, Nihon University School of Dentistry, Tokyo, Japan
Overdentures were classified into three groups based on the presence/absence of canine copings: Group I, thosewith a coping on the canine of one side; Group II, those with two copings on both sides of the canine; and Group
III, those without any coping on the canines. Three groups were further sub-classified on the basis of numberand location of other copings. This classification system (Sakurai Classification) is useful for the arrangement ofroot caps and designing of magnetically retained overdentures. (Int Chin J Dent 2006; 6: 93-95.)
Key Words: classification, complete denture, coping, overdenture.

Introduction
Over the last decades, the use of magnetic attachment systems has increased considerably. Exchange ofinformation between clinicians and researchers on the effectiveness of various dentures would be beneficial withthe use of a simple method of denture classification. Several methods concerning the classification of missing
teeth as well as removable partial dentures have been reported.1-4 The authors propose a new and simple
classification system for complete overdentures.5

Classification
This classification system identified as the Sakurai Classification comprises three major groups based on thepresence/absence of canine copings: Group I, those with a coping on the canine of one side; Group II, those withtwo copings on both sides of the canine; and Group III, those without any coping on the canines (Table 1).
Table 1.

Classification of complete overdentures based on location of canine coping.

Group IIIAIBIUIABIAU

Coping on canine on one side
Coping on canine on one side
Copings also present on anterior teeth
Copings also present on bilateral molars
Copings also present on unilateral molars. If the molar is opposite the canine, use IUO.
Copings also present on anterior teeth and molars on both sides
Copings also present on anterior teeth and molars on one side. If the molar is on the opposite side, use IAUO.

Group IIIIIIA
IIB
IIU
IIAB
IIAU

Copings on canines on both sides
Copings on canines on both sides
Copings also present on anterior teeth
Copings also present on bilateral molars
Copings also present on unilateral molars
Copings also present on anterior teeth and molars on both sides
Copings also present on anterior teeth and molars on one sideGroup III
III
IIIA
IIIB
IIIU
IIIAB
IIIAU

Canines without copings
No coping
Copings present on incisors
Copings present on bilateral molars
Copings present on unilateral molars
Copings present on incisors and molars on both sides
Copings present on incisors and molars on one side93

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Int Chin J Dent 2006; 6: 93-95.

Further classification was performed based on the number and position, including bilateral or unilateral, of thecopings. Where copings were present on the incisors, the case was classified as Anterior (A). Where copings
were present on molars, the case was classified as bilateral (B) or unilateral (U). For Group I cases, opposite (O)was added if the molars exist on the opposite side of the canines. The number of copings was added after A, Bor U.

This classification consists of (1) the major classifications of Groups I, II, and III; (2) the minor

classifications of A, B, U, and O; and (3) the number of copings.

Fig. 1.
Left
IU1Group I, unilateral canine coping
one posterior unilateral coping
Fig. 2.
Right
IU1O
Group I, unilateral canine coping
one posterior unilateral coping
opposite side
opposite side
Fig. 3.
Left
IIA1B2
Group II, bilateral canine copings
one anterior coping
two posterior bilateral copings
Fig. 4.
Right
IIA1U1
Group II, bilateral canine copings
one anterior coping
one posterior unilateral coping

Fig. 5.
Left
IIIA2B3Group III, no canine coping
anterior two copings
three posterior bilateral copings
Fig. 6.
Right
IIIA1U2Group III, no canine coping
one anterior coping
two posterior unilateral copings

Fig. 1 shows the Group I dentition, in which the coping is on the canine of one side. This case is further
classified as IU because a molar on the same side also has a coping. The number of copings can be reported byadding an Arabic numeral after A, B, or U. According to our definition, the proper expression for the case of Fig.
1 will be IU1. The case of Fig. 2 is also classified as Group I since the canine coping is on one side. This case,however, can be classified as IU1O due to the molar coping located on the opposite side of the canine.
Figs. 3 and 4 show the cases classified as IIA since the copings are on bilateral canines and other anterior teeth.
Fig. 3 can be categorized as Group II since the copings are on both canines. Further, the case is classified as
IIA1B2 since there are an anterior coping and two bilateral copings in the premolars. The case of Fig. 4 primarily
classified as Group II is further classified as IIA1U1, since both of an incisor and a premolar have a coping.
Group III is used for the cases involving canines without copings. Fig. 5 is classified as IIIA2B3 due to two
anterior copings and three bilateral posterior copings. Fig. 6 should be classified as IIIA1U2 because there arethree copings in each of a lateral incisor, a premolar, and a molar. Both the premolar and molar were located on
the left side, and the U-B category is judged as unilateral (U).

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Int Chin J Dent 2006; 6: 93-95.

Fig. 7.
IU1OGroup I, unilateral canine coping
one posterior unilateral coping
opposite sideFig. 7 demonstrates a typical IU1O case, in which a coping is on the right canine and an opposite molar. Thiscase is exactly the same category as the case of Fig. 2.
The original Japanese version of the Sakurai Classification has been published in reference 5 (Sakurai et al. 2002).

References
1. Godfrey RJ. Classification of removable partial dentures. J Am Coll Dent 1951; 18: 5-13.
2. Skinner CN. A classification of removable partial dentures based upon the principles of anatomy and physiology. J Prosthet
Dent 1959; 9: 240-6.
3. Avant WE. A universal classification for removable partial denture situations. J Prosthet Dent 1966; 16: 533-9.
4. Miller EL. Systems for classifying partially dentulous arches. J Prosthet Dent 1970; 24: 25-40.
5. Sakurai H, Ishigami T, Takagi Y, et al. A proposal for complete denture of overdenture (Sakurai Classification). J J Mag Dent
2002; 11: 9-13.

Correspondence to:Dr. Tomohiko Ishigami
Department of Partial Denture Prosthodontics, Nihon University School of dentistry
1-8-13 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-8310, Japan
Fax: +81-3-3219-8350 E-mail: ishigami-t@dent.nihon-u.ac.jp
Received June 2, 2006. Accepted July 18, 2006.
Copyright ©2006 by the International Chinese Journal of Dentistry.

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