Classifying Periodontal Diseases – a Long-Standing Dilemma

Periodontology 2000, Vol. 30, 2002, 9–23 Copyright C Blackwell Munksgaard 2002 Printed in Denmark. All rights reserved PERIODONTOLOGY 2000 ISSN 0906-6713 Classifying periodontal diseases – a long-standing dilemma G C. A A long-standing dilemma have been superimposed on a matrix of older ideas that are still considered to be valid. Only those ideas Any attempt to group the entire constellation of peri- that are believed to be clearly outmoded or incorrect odontal diseases into an orderly and widely accepted have been discarded. In a sense, the newest or domi- classification system is fraught with difficulty, and nant paradigm rests on a foundation of the still valid inevitably considerable controversy. No matter how components of the older or previous paradigms. carefully the classification is developed, and how One of the interesting historical features of classi- much thought and time are invested in the process, fication systems is the often intense resistance to choices need to be made between equally unsatis- their modification. Many people appear to believe factory alternatives. Despite this dilemma, in the that classification systems are rigid and fixed entities past hundred years, experts have periodically as- that should not be changed. In fact, classification sembled to develop a new classification system for systems should be viewed as dynamic works-in-pro- periodontal diseases, or to refine an existing one (1, gress that need to be periodically modified based on 2, 4, 5, 11, 19, 58, 80, 81, 86, 91, 106, 122, 139). current thinking and new knowledge. Unfortunately, it seems that once people learn and accept a given classification, no matter how flawed it may be, they are extremely reluctant to accept revisions to their Dominant paradigms in the favorite system of nomenclature. One group of ex- historical development of perts on the 1949 Nomenclature Committee of the classification systems American Academy of Periodontology (AAP) expressed their frustration with this subject by stating, The development and evolution of classification sys- ‘The 1949 Nomenclature Committee is somewhat tems for periodontal diseases have been largely in- pessimistic regarding the possibility of this or any fluenced by paradigms that reflect the understand- similar report receiving immediate and enthusiastic ing of the nature of periodontal diseases during a acceptance. Most periodontists have used their own given historical period. Over time, thoughts that terms for so long that any suggested change is re- guided the classification of periodontal diseases can sisted and resented.’ (81) be placed into three dominant paradigms primarily based on the clinical features of the diseases Clinical characteristics paradigm (ϳ1870–1920), the concepts of classical pathology (ϳ1920–1970), and the infectious etiology of the dis- For the period from approximately 1870 to 1920 very eases (ϳ1970–present). Classification systems in the little was known about the etiology and pathogenesis modern era represent a blend of all three paradigms of periodontal diseases. Accordingly, the diseases since there is a certain amount of validity to some of were classified almost entirely on the basis of their the earliest thoughts about the nature of periodontal clinical characteristics supplemented by unsubstan- diseases (2, 4, 5). As classification systems have tiated theories about their cause. At the time, one evolved, newer thoughts about periodontal diseases of the main debates about the nature of periodontal 9 Armitage diseases was whether they were caused by local or is initiated and continued without any visible systemic factors. Most authors considered these dis- mechanical irritant in many cases; and I believe eases to be primarily caused by local factors (16, 53, the death of the peridental membrane, depriving 93, 111, 112, 125, 127, 136, 149), whereas some be- the alveolus of nutrition, accounts for the death lieved that systemic disturbances played a dominant and disintegration of the bone; or, as is believed etiological role (32, 97, 114, 115). Many of the advo- by some, among them Dr Waters, of Boston, the cates for the etiological role of local factors also ac- alveolus is destroyed by vegetable parasites’. knowledged that in some cases both local and systemic factors were important (93, 112, 113, 136). In Similarly, in 1886 G.V. Black (15) published his the late 1800s and early 1900s clinicians used case thoughts on the classification of periodontal diseases descriptions and their personal interpretation of based on their clinical characteristics and his under- what they saw clinically as the primary basis for standing of their cause into five separate groups. classifying periodontal diseases (15, 17, 28, 53, 111– 113, 125, 127, 136, 137, 149). They expressed their O constitutional gingivitis; including mercurial gingi- opinions, often with great fervor and conviction, in vitis, potassium iodide gingivitis and scurvy. oral presentations before local and national meet- O a painful form of gingivitis. Black described a clin- ings of dental or medical societies. Their opinions ical condition that resembled what is now termed survive in the literature in the form of written ab- necrotizing ulcerative gingivitis (NUG), but he stracts or summaries of the proceedings of these never used the term. meetings. In many cases the summaries were written O simple gingivitis. This was associated with the ac- not by the presenter of the paper, but by the editor cumulation of debris that eventually led to ‘calcic of the proceedings (125, 127). Indeed, John M. inflammation of the peridental membrane.’ Riggs(1811–1875), an American dentist who lectured O calcic inflammation of the peridental membrane. so widely on the treatment of periodontal diseases This was associated with ‘salivary’ and/or ‘serumal’ that periodontitis was called ‘Riggs’ disease’ by many calculus. Usually there was an even or generalized of his colleagues, rarely published any papers on the pattern of destruction of alveolar bone. The de- subject (89). Riggs’ thoughts and opinions were most struction usually occurred slowly. Black’s descrip- often summarized by others (94–96, 127). tion best fits the periodontal disease that is now Formal papers on the classification of periodontal known as chronic periodontitis. diseases were rare in the late 1800s and early 1900s. O phagedenic pericementitis (phagedenic Ω spread- Typical publications on the subject usually repre- ing ulcer or necrosis). This condition shared many sented the opinion of a single person who almost features with ‘calcic inflammation of the peridental always based the classification on clinical obser- membrane’ but there was an irregular pattern of vations and theoretical explanations of causation. A destruction and not much dental calculus. De- good example is a paper published by C.G. Davis in struction of the alveolar bone can occur slowly or 1879 (28) who believed that there were three distinct rapidly. In a later publication Black replaced the forms of destructive periodontal disease: term ‘phagedenic pericementitis’ with ‘chronic suppurative pericementitis’ (17). O Gingival recession with minimal or no inflammation. This was due to ‘... feeble vascular action The point of these historical examples is to emphasize ...’ and trauma from tooth brushing or other that little or no scientific evidence was used to sup- sources. port the opinions of the clinicians of the time. As one O Periodontal destruction secondary to ‘lime de- might expect, the number of theories about what posits’. ‘The gum retires slowly ... and the alveolar caused periodontal diseases, how they should be border, deprived of nutrition at the point of press- classified, and the terminology used to describe them, ure, is consentaneously absorbed.’ Davis appar- seem to have approached the number of clinicians ently believed that calculus exerted mechanical who treated patients with these diseases. By 1929 one pressure on the gingiva causing the alveolar bone author estimated that there were ‘... over 350 theories to resorb because of lack of nutrition. of pyorrhea’ and much confusing terminology (10). It O ‘Riggs’ Disease’ the hallmark of which was, ‘... loss is not surprising then, that no generally accepted ter- of alveolus without loss of gum.’ The perceived minology or classification system for periodontal dis- problem was a ‘necrosed alveolus’ or death of the eases was adopted during this era. As a result, in the periodontal membrane. ‘... we get a disease that latter part of the 19th century periodontitis went 10 Classifying periodontal diseases under numerous names including: ‘pyorrhea al- ally be called localized aggressive periodontitis (4). veolaris’ (19, 53, 93, 111, 112, 125, 136, 137, 149), The impact of Gottlieb’s work on classification sys- ‘Riggs’ disease’ (28, 94–96), ‘calcic inflammation of the tems was profound since it suggested that some peridental membrane’ (15), ‘phagedenic pericemen- periodontal diseases were degenerative. As a result, titis’ (15, 19), and ‘chronic suppurative pericementitis’ almost all classification systems used from approxi- (17). During this period, the dominant term used for mately 1920–1970 included disease categories destructive periodontal disease was pyorrhea al- labeled as ‘dystrophic’, ‘atrophic’, or ‘degenerative’ veolaris. (Fig.1). Classification systems of the period were dominated by the ‘Classical Pathology’ paradigm Classical pathology paradigm which is based on the ‘principles of general pathol- (ϳ1920–1970) ogy’ as articulated by Orban

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