Topographie Classification of Deformities of the Alveolar

Transcription

1 Topographie Classification of Deformities of the Alveolar Process* Kenneth W. Karn.f Howard P. Shockett^ William C. Moffitt and Jonathan L. Gray Accepted for publication 1 August 1983 A system of nomenclature for deformities of the alveolar process is presented. Descriptive, familiar topographic terms are used (crater, trench, moat, ramp and plane), and specific criteria are given for each term. Two hundred randomly selected osseous deformities in dry skulls were classified by two examiners at independent sessions using the proposed system. One hundred ninety of these defects were given identical descriptions. The nomenclature system is proposed to facilitate communication among practitioners concerning osseous deformities of the alveolar process, as well as to permit comparison of the effectiveness of various therapeutic modalities directed toward bone regeneration in periodontics. In 1959 Bertram Cohen1 introduced the term "col" into the dental literature to describe the depression often found between the facial and lingual papillae of proximal contacting teeth. The term is a familiar one to civil engineers and geologists to describe "a pass between two peaks or a saddle-shaped depression in a ridge." Because the term is so graphic, it provides immediate comprehension and has therefore come into common usage in periodontics. Descriptions of other topographic features of the periodontium, specifically deformities resulting from destruction of the alveolar process by periodontal disease, have not provided such ready understanding. When the original topography of the alveolar process is altered by uniform loss of bone from around the teeth, the term horizontal bone loss has been applied, and it is readily understood. Difficulty arises when describing deformities created by nonuniform loss of bone. This paper will describe nomenclature adapted from readily understood terms which are presently in common use. This should facilitate clear communication among practitioners as well as ready acceptance of the system. In addition, the terms are given specific criteria for their use and hence may be of value in the evaluation and prediction of therapy performed to permit regeneration of bone. Although the terms used in this system are simple, their use initially seems complicated. * This article contains the opinions and work of the authors and in no way reflects those of the US Air Force, US Navy or its agencies, t Major, US Air Force Dental Corps. i Private Practice, Baltimore, MD. Associate Professor, Department of Periodontics, University of Maryland Dental School, Baltimore, MD. II Commander, US Navy Dental Corps. With minimal experience, however, one can quickly develop fluency in using them. NOMENCLATURE OF DEFORMITIES OF THE ALVEOLAR PROCESS The term "horizontal bone loss" is readily understood and is retained. The proposed system of nomenclature for bony deformities caused by nonuniform loss of bone is based on the following basic terms: crater A crater is formed as a result of loss of alveolar bone and a portion of the contiguous supporting alveolar bone from only one surface of a tooth (see Figs. 1-3). trench This term is applied when such bone loss (see above) affects two or three confluent surfaces of the same tooth (see Fig. 4). moat When the previously described deformity involves all four surfaces of a tooth, it is described as a moat. ramp In its purest form the term ramp describes a deformity that results when both alveolar bone and its supporting bone are lost to the same degree in such a manner that the margins of the deformity are at different levels (see Figs. 5 and 6). plane This term is applied when both alveolar bone and supporting bone is lost to the same degree such that the margins of the deformity are at the same level.

2 Volume 55 Number 6 Classification ofdeformities ofthe Alveolar Process 337 Figure 1. Alveolar bone proper (lining socket) and supporting alveolar bone in between. Figure 3. Faciolingual cross section ofcrater. Figure 4. Facial view ofmesiofacial trench #18. Figure 2. Facial view ofone-surface crater mesial #!9 and two-surface crater between #18 and #19. It can be considered horizontal bone loss about one tooth or portion of a tooth (see Fig. 17). The preceding basic terms are qualified with the following criteria: crater Craters are identified by the tooth surface involved (mesial, distal, facial or lingual). Craters may be confluent if they occur on adjacent proximal surfaces, in which case they are called two-surface craters (affecting two tooth surfaces) and are named for the two teeth involved. Figure 2 demonstrates the distinction between one- and two-surface craters. trench Trenches can be similarly identified by the tooth surfaces involved (e.g., mesiofacial, mesio-lingual-distal, etc.). Since trenches involve either two or three surfaces of the same tooth there are eight possible Figure 5. Facial view ofmesial ramp #18 and facial ramp # Figure 6. Facial view ofmesiofacial ramp #18.

3 338 Kam, Shockett, Mojfitt, Gray types (MF, ML, DF, DL, MFD, MLD, FML, FDL) (see Fig. 4). moat Since the term "moat" is applied to a deformity totally encircling a tooth, only the tooth number is necessary to identify it. ramps Ramps are named for the tooth surface aspect from which the greatest bone loss has occurred and the teeth involved. Thus a facial ramp between Teeth #20 and #21 (Fig. 5) describes a deformity in which the lingual margin is coronal to its facial margin (bone has been lost from the facial aspect of the interdental septum). Similarly a mesial ramp on Tooth #18 describes a deformity in which the bone on the mesial of Tooth # 18 is at a more apical level than the bone on the distal of #19 (see Fig. 5). Visualization and classification of ramps become J. Periodontol. June more complex when a ramp-type deformity demonstrates loss of bone from more than one aspect. Figures 6 and 7B demonstrate a mesiofacial ramp on Tooth #18. If some bone were lost on the distofacial aspect of Tooth #19, but the loss were not as severe as that on the mesiofacial of #18, then the deformity would be termed a mesiofacial ramp between #18 and 19. Facial and lingual ramps, in addition to being found Figure 9. Facial view ofa mesial ramp into a one-surface crater #15. Compare this defect with the cratered ramp in Figure 8. A Figure 7. 77?c' mesiofacial ramp on #18 as seen in Figure 6 is shown here as cross sections of the distal of #19, A, and the mesial of #18, B. 777c' differential hone loss across the interdental septum is evident. Figure 8. Facial view ofa facial cratered ramp between #20 and #21. Note the lingual crest of the crater is more coronal than the facial crest. Figure 10. A, a direct facial view of a facial crater into a Class II furcation #31.B,a more coronal view revealing the defect more clearly.

4 Volume 55 Number 6 Figure 11. Palatal view of a mesiopalatal ramp into a shallow onesurface crater #14. Classification ofdeformities ofthe Alveolar Process 339 Therefore, such ramps are named for the alveolar process aspect (rather than the tooth surface aspect) from which bone has been lost. If this were not done, a facial interproximal ramp would change names to a lingual ramp if the deformity involved the lingual tooth aspect as well. This represents the only exception to the ramp nomenclature rules. Periodontal osseous defects are found which demonstrate characteristics of more than one of the above described categories: cratered ramp An example of this defect is shown in Figure 8. If only the most coronal rim of the deformity were considered, it would represent a ramp. However, a crater is present apical to the entire extent of the ramp and hence the term "cratered ramp." It is basically a crater with a portion of its facial and/or lingual wall missing. Cratered ramps are named for the teeth involved, the aspect of the alveolar process from which bone has been lost in the ramp portion and the tooth Figure 12. Facial view ofa facial ramp into a mesial crater #2. Figure 14. Palatal view of two-surface crater #3-4, a mesiopalatal cratered ramp into a Class II furcation #2 and a palatal ramp (only facial wall exists) #1-2. Figure 13. Facial view ofa mesiofacial cratered ramp #31. interproximally, may also be seen facial and lingual to the teeth. This is usually the case when thick alveolar bone existed before the bone loss occurred and is almost always in combination with interproximal ramps. Figure 15. Palatal view of a steep mesial ramp (loo dark to see, but no facial wall exists) tooth #14. Note probe does not reveal infrabony defect apical to palatal andfacial crests ofdefect.

5 340 Kam, Shockett, Mqffitt, Gray Figure 16. Facial view ofmesiofacial ramp (note probe) #3 andfacial ramp #2-3. Figure 17. Facial view of a plane with Class III furcation on Tooth #30. surfaces involved with the crater (or trench). Figure 8 illustrates a facial cratered ramp between Teeth #27 and 28. ramp into a crater or trench This deformity is depicted in Figure 9. It differs from the cratered ramp in that the most coronal aspect of the deformity is distinctly a ramp and the apical portion is distinctly a J. Periodontol. June, 1984 crater or trench. Figure 9 shows a ramp into a mesial crater on Tooth #15. furcation invasions The furcation may become involved by horizontal bone loss or by one of the previously detailed deformities. Descriptions of furcation invasions should include a notation of the degree of involvement (Class I, II or III).2 The individual using this system may be as detailed as he desires. For most purposes one may simply use the appropriate defect term (Fig. 10 is a facial crater into a Class II furcation). For a more precise description of the osseous topography, one may consider each root as if it were a separate tooth and describe the area using all of the preceding criteria. Figures offer several examples of the above system of nomenclature. CLASSIFICATION SYSTEM IN USE Two of the authors (KWK, HPS) classified, independently, 200 defects found in skulls of the Terry collection at the Smithsonian Institution Museum of Natural History. Each defect was grouped into one of six categories (crater, ramp, trench, moat, cratered ramp or ramp into crater). The exact description of the defect was given according to the previously described criteria. Of the 200 total defects, 190 were given identical descriptions by the two examiners. Of the 10 defects given nonidentical descriptions, 6 were discrepancies between pure ramps and shallow cratered ramps, 2 were differences between ramps into craters and cratered ramps and 2 were differences between ramps and cratered ramps into maxillary proximal furcations. This small study does not validate the reproducibility of the proposed classification system. It does, however, lend some degree of optimism for its acceptance and potential usefulness. REFERENCES 1. Cohen, B.: Morphologic factors in the pathogenesis of periodontal disease. Br Dent J 107: 31, Carranza, F.: Glickman's Clinical Periodontology, ed 5 pp Philadelphia, W. B. SaundersCo, Send reprint requests to: Kenneth W. Kam. DDS, 5710 Cahalan Ave, Suite 4, San Jose, CA