The True History of Cementoblastoma

Review of the literature

Cementoblastoma (CB) is unique among odontogenic tumors because its gross pathological anatomy is pathognomonic in most cases, i.e., a rounded calcified growth that is fused to the root of a tooth and completely encapsulated by fibrous tissue. The resulting radiographic appearance is a well-defined, globular mixed radiopaque/lucent or completely radiopaque mass obliterating some details of the root, with a thin radiolucent zone surrounding the central opacity. Although hundreds of publications have covered the clinicopathologic features of CB, almost nothing is known about its true history. Also it seems there is little understanding about how the term “CB” was originally introduced as a pathologic entity. This report covers some overlooked papers on CB dating back to the 19th century, including the first complete description in 1888 and the first radiographic presentation in 1906.

Metnitz’s Study of Odontoma in 1888: The Oldest Verified Case of Cementoblastoma (CB)

Metnitz [1], who was professor of dentistry at the University of Vienna, published a major report entitled “Odontome” in 1888. This four-part journal paper in German was republished three years later as “Anomalien der Zahnbildung” in Metnitz’s textbook “Lehrbuch der Zahnheilkunde” [2], and an English-language translation appeared in the Dental Review published in 1889 [3]. The first section of Metnitz’s seminal work detailed the clinical and pathological characteristics of a case of CB, representing one of the most striking examples in terms of the following features: (1) the patient an 11-year-old boy; (2) the lesion was a swelling in the left posterior mandible accompanied by steadily increasing pain (Fig. 1 A); (3) the mass was hard and rounded measuring 22 × 22 × 20 mm associated with both a canine and first molar of the primary dentition (Fig. 1B); (4) root resorption was evident (Fig. 1 C,D); (5) complete coverage with periosteum (perhaps a fibrous capsule); (6) no genuine bone formation in the central areas; (7) rows of many bone cells (perhaps cementoblasts) along trabeculae with a bone-like appearance; (8) a highly vascular stroma; (9) involvement of the pulp chamber (Fig. 1D); and (10) a presumptive origin from the cementum (Fig. 1E). Although this particular case was diagnosed under the term “odontoma” commonly in use at that time, it is clear that Metnitz’s description accurately matched that of a CB.

Fig. 1.

Clinical view (A) and gross (B,C) and microscopic (D,E) image of cementoblastoma reported in 1888 by Metnitz [1]. e Metnitz’s original illustration showing dentin (left), cementum (center) and tumor (right) [4]

The remaining three parts of Metnitz’s paper were devoted to a systematic search of odontoma cases that had been reported up to that time [1]. Many of the professional drawings were sources for the 2nd revision of “Atlas zur Pathologie der Zähne” published in 1893 [4]. For European surgeons and pathologists, Metnitz’s case became a focus of interest and was cited multiple times in subsequent textbooks [5–9]. Among them, Smale and Colyer [6] of London appear to have been the first to introduce Metnitz’s CB to the British literature, although it was listed as an example of radicular odontoma, as was common at the time. This German report predated the first American paper on CB, by Dewey [10] of Chicago, by more than four decades. For some reason, Dewey [10] gave a summary account of Metnitz’s case without citation of the original publication.

Earlier Reports of Great Controversy

In view of the long history of CB, we have been able to retrieve three possible cases that predate Metnitz [11–13]. In 1839, Rodrigues [11] of Charleston wrote a brief clinical paper on exostosis of the right maxilla in a female patient. Although no illustrations exist, two authoritative reviews on the history of odontogenic tumors concluded that this was the first journal reference to CB [14, 15]. Since Rodrigues’s surgical descriptions did not include the key clinical feature of association of a bony tumor with the roots of the right maxillary teeth (several of which had been removed previously) [11], we consider that it probably fell within the spectrum of infected osteoma of the maxillary sinus or sequestrum due to long-standing jawbone inflammation. One of the above two articles also referred to “exostosis on the fang” reported in 1855 by Salter [12] of London as the first example of CB with microscopic confirmation [14]. Unfortunately, there is currently no way to be certain whether this small lesion represents a true CB or nondescript deposits of cemento-osseous tissue around the apex (Fig. 2).

Fig. 2.

Gross (A) and microscopic (B) appearance of exostosis described in 1855 by Salter [12]

In 1868, Letenneur [13] of Nantes studied an interesting tumor under the diagnosis “Odontôme radiculaire cémentaire (d’exostose éburnée)” in a 34-year-old woman, who presented with an infected irregular 3.5 × 2.5-cm bony mass attached to one side of the root of the left mandibular first premolar. Microscopic examination of a piece reveled cementum-like tissue (for which the eminent Broca presented a pathology report). Unfortunately, however, its true nature was not readily apparent in his non-illustrated meeting report [13]. As the number of similar cases increased, the English term “radicular odontoma” pervaded the literature until the publication of the first WHO classification in 1971 [16].

Taxonomical Controversy Related to CB

For a century, the term “cementoma” had been loosely used for all cementum-forming lesions, including hypercementosis, cemento-osseous dysplasia, gigantiform cementoma, CB and cemento-ossifying fibroma. To our knowledge, Sonesson [17] of Malmö in 1949 was the first author to describe a true case of “CB under that name”, although he did not recognize it as a distinct entity. As shown in Table 1, the term “CB” had its origin in the 1926 textbook “Pathologische Histologie der Mundhöhle” written by Siegmund and Weber [18] of Cologne. On the basis of their descriptions and one photomicrograph provided, the German term “Zementoblastom” was apparently applied to cemento-ossifying fibroma. In 1937, the English term “CB” was adopted by Thoma [19] to define focal and multiple fibro-osseous lesions that are referred to today as cemento-osseous dysplasia. Thoma was professor of oral pathology at Harvard University Dental School and a central figure in the American Academy of Oral Pathology. He referred to “Zementoblastom” described by Siegmund and Weber [18] and modified its conceptual use as mentioned above. His classification scheme was retained in his subsequent publications until 1960 [20–23]. Probably because of Thoma’s influential view, almost all pathologists repeatedly expressed a similar opinion [24–37].

Table 1.

Conceptual controversy related to cementoblastoma before 1970*

Year	Authors	Original nomenclature	Current diagnosis
1926	Siegmund/Weber [18]	Zementoblastoma	Cemento-ossifying fibroma
1937	Thoma [19]	Cementoblastomab	Cemento-osseous dysplasia
1942	Bernier [24]	Cementoblastomab	Cemento-osseous dysplasia and cementoblastoma (?)c
1949	Sonesson [17]	Cementoblastometb	Cementoblastoma
1950	Sonesson [26]	Cementoblastomab	Cemento-osseous dysplasia
1951	Pindborg [27]	Cémentoblastomeb	Cemento-osseous dysplasia
1953	Husted/Pindborg [28]	Cementoblastomab	Cemento-osseous dysplasia
1958	Shafer et al. [30]	Cementoblastomab	Cemento-osseous dysplasia
1960	Bernier [32]	Cementoblastoma	Cemento-ossifying fibroma (?)d
1966	Dechaume [35]	Cémentoblastomeb	Cemento-osseous dysplasia
1969	Vilasco et al. [37]	Cémentoblastome	Cementoblastoma

* The final version of the 1971 WHO classification was completed in 1969 [16].

^a The term “Zementodontom” was adopted as a synonym.

^b The term “cementoma” was also used.

^c One photomicrograph provided probably depicts cementoblastoma.

^d The diagnosis “cementifying fibroma” was not evident in four photomicrographs published.

In 1942, Bernier [24] (chief of oral pathology at the Armed Forces Institute of Pathology [AFIP]) divided calcified odontomas (all odontogenic tumors being called odontoma at that time) into dentinoma and CB, the latter of which was also referred to as cementoma. Thirteen years later, in 1955, he emphasized that the diagnostic terminology “cementoma” should be restricted to solitary or multiple lesions attached to the roots and did not employ the term “CB” in his textbook “The Management of Oral Disease” [29]. It seems likely that “attached” cementoma may have been a form of CB. In their 1958 book “A Textbook of Oral Pathology”, the American pathologists Shafer, Hine and Levy [30] proposed two categories, cementoma and true cementoma; the former included the term “CB” in round brackets and the latter was applied for a genuine example of CB. The term “true cementoma”, which originally appeared in the 1914 British publication “Report on Odontomes” [38], also appeared in Bernier’s 1955 textbook [29]. Interestingly, the first series of “Atlas of Tumor Pathology” published in 1960 by the AFIP (edited by Bernier) used the term “CB” synonymously with cemento-ossifying fibroma, and an example of CB was illustrated in the section of cementoma [32]. Soon after, Gorlin et al. [34] in the United States suggested that within a group of cementum-producing lesions, true cementoma (synonym: CB) and gigantiform cementoma were in the same neoplasm. It is unfortunate that during this period, many other designations had been randomly proposed by different authors. For example, Dewey [39], who reported the first American case of CB in 1927 under the diagnosis of osteoma [10], adopted the term “genuine cementoma” in 1931 to describe periapical cemento-osseous dysplasia.

In 1970, Pindborg [40] of Copenhagen, a leading authority on odontogenic tumor pathology, wrote a textbook “Pathology of the Dental Hard Tissues”, which added an informal comment that Kramer (dean and professor of oral pathology at the University of London), who collaborated with Pindborg to publish the 1971 WHO blue book [16], had originally suggested the diagnostic term “benign” CB. In this situation, it was natural for a group of pathologists designated by the WHO to have chosen this term, and interestingly “true cementoma” was provided in square brackets as a synonym [16]. Since then, the blanket term “cementoma” gradually fell out of favor. Based on the fact that no malignant counterpart had ever been noted [41], the prefix “benign” was dropped from CB in the 2nd series of the AFIP Atlas as early as in 1987 [42].

Unknown CBs: An Early Radiographic Presentation

As alluded to above, microscopic examination is not always necessary for a typical case of CB because of its pathognomonic clinicoradiological features. By the time the 1971 WHO guideline was released [16], six overlooked radiographs of CB were available for review [43–48]. Although diagnostic radiography was not in routine use until the beginning of the 20th century, Bland-Sutton [43] of London, one of the most brilliant pathologists of his generation, published in 1906 a report on radicular odontoma of the left mandibular second molar in a 15-year-old boy. Two macroscopic drawings and one excellent radiograph clearly depict the fusion of a large globular tumor to the roots (Fig. 3). This little-known study probably represents the first radiographic presentation of CB and was included in the 3rd edition of his book “Tumours Innocent and Malignant” published in 1907 [49].

Fig. 3.

Radiographic (A) and gross (B) appearance of cementoblastoma reported in 1906 by Bland-Sutton [43]

The 1915 textbook “Surgery and Diseases of the Mouth and Jaws” written by Blair [44] (professor of oral surgery at Washington University Dental School) presented a radiographic description of CB in the right mandibular first molar of a 16-year-old girl, using the term cementoma in the figure legend (Fig. 4 A). A good radiograph of CB was subsequently published in two German books [46, 48] (Fig. 4B-D) and two American journals [45, 47]. Of particular interest to pathologists is that one of the above textbooks also included a photomicrograph of CB, although the image was not so clear [48]. Considering the findings overall, it seems reasonable that several cases of exostosis [50] (Fig. 5 A), dental osteoma [51], cementodontoma [52], cementosteoma [53], cementoma [54], hypercementosis [55] or radicular odontoma [56, 57] (Fig. 5B) described in the earlier literature would likely have included CB.

Fig. 4.

Radiographs of cementoblastoma. a Blair’s case published in 1915 [44]. b Cementoblastoma of the right mandibular second and third molars in a 20-year-old female presented in 1938 by Hellner [48] (reprinted with permission). c,d Cementoblastoma of the right mandibular first and second molars in a 17-year-old girl provided in 1930 by Sonntag and Rosenthal [46] (reprinted with permission)

Fig. 5.

a Exostosis in situ of the right mandibular second molar depicted in 1847 by Tomes [50]. b Radicular odontoma of the right maxillary third molar described in 1894 by Watson [56]

Conclusion

In the present study, we have expanded and revised the history of CB. Credit for the earliest complete description of CB belongs to Metnitz [1] of Vienna in 1888. One of the most important aspects was his remarkable insight into its origin from the cementum. Despite its historical importance, Metnitz’s contribution was forgotten. A British report published in 1906 by Bland-Sutton [43] provided the first radiographic evidence of CB. No additional case of CB appeared in his subsequent review of radicular odontoma [49]. Despite persistence of the same nomenclature, the concept of CB has seen frequent changes over the years, and modern knowledge of CB was undoubtedly established from American studies [30, 58–60]. On several occasions, the old literature might have included descriptions of CB under a wide variety of names [38, 49]. Precise understanding of the centennial history of CB may allow pathologists to comprehend the current classification for fibro-osseous lesions of the jaw.

Author Contributions:

FI contributed to the conception and design of the study, and wrote the original draft. SS & YM edited the manuscript. MH & MN were responsible for data interpretation. TM conducted a literature search. KK approved the final version of the manuscript. All authors confirm they have contributed to the study and read and approved the final manuscript.

Funding

Not applicable.

Data Availability

The data are available upon reasonable request.

Code Availability

Not applicable.

Declarations

Conflict of Interest

All authors declare that they have no conflict of interest.

Ethical Approval

For this type of retrospective study, ethical approval is not required.

Consent for Participate

Not applicable.

Consent for Publication

Not applicable.