Taurodont molars: Review of literature and radiological features

  T. Saini, BDS,MS,Dip ABOMR*,
C. A. Wilson, BDS,MS,DRD,MFD,LDSRCS**
King Saud University, College of Dentistry, P.O. box 60169, Riyadh 11545, Saudi Arabia

Taurodontic molar teeth are present as a clinical entity in modem man. This is a suggestion that the occurr­ ence has a racial bias. The importance of the differential diagnosis of teeth with enlarged pulp is discussed, and the possible influence of taurodontic molars on treatment planning is outlined.

The term "Taurodontism" was first coined by Keith in 1908.1 According to him, the taurodont molars are characterized by extension of the pulp chamber well beiow the level of alveolar crest and cemento-enamel junction. In contrast, cyanodonts which represent the norm in carnivore mammals and modern man, are typified by a relatively small pulp chamber whose apical extension is limited to the cemento-enamel junction and is located coronal to the alveolar crest.

Taurodont molars were first found and examined radiographically in 100,000 year-old skeletal remains from Krapina in 1906.2 Krapina remains have been assigned to neanderthal man who lived during the Mousterian period of the Pleistocine era in Europe and became extinct circa 40,000 years ago. Based on the prevalence of taurodont molars in neanderthal individuals as compared to modern man, AdIoff3 supported Schwalbe's conclusions that neanderthal man con­ stituted a totally distinct species of humanity. Weidenreich,4 while examining 147 tooth remains of homo erectus from Choubouteien near Peking, found the presence of moderate taurodontism in remains of one mandible only. He assumed that the larger pulp chambers in taurodont ensured more tertiary dentin formation in the presence of progressive attrition of the occlusal surfaces due to the intake of rough diets. Human tooth specimens from Predmost excavation revealed intermixing of cynodont molars with taurodont molars. Tratman5 inferred that neanderthal man and modern man might have existed at the same time and would have inter-bred. Senyurek6 in 1939 noted taurodontism in the teeth of ancient Egyptians, ancient Icelanders and early American Indians. Taurodontism has been found in the dentition of modern races. Shaw7 reported the incidence to be as high as 30 per cent in hybrids of Australoids and the Bush people of South Africa. Taurodontism has been found in mongoloid and negroid8 popula­ tions. Ruprecht et al9 reported a high prevalence rate (11.3 per cent) among 1581 Saudi Arabian dental patients. Halks and Brooks10 found the pre­ valence to be low (0.90 per cent) in a sample of 1602 dental patients in the United States consisting of mixed ages and races. The incidence seems to be rare in people of caucasoidal origin. Tratman5 described the existence of taurodont molars in con­ temporary anthropoid apes.

Taurodontism is classified according to the degree of apical location of the pulpal floor and can be designated as hypotaurodont, mesotaurodont, and hypertaurodont. Another variety is described whereby the pulp chamber demonstrates a gradual

taper culminating at the apex and is termed prisma­ tic or cuneiform taurodont.

Taurodontism is seen more commonly in per­ manent dentitions and is found to be a rare occurr­ ence in primary dentitions. The second permanent molar is most commonly involved. It seems to be a hereditary condition expressed by a polygenic sys­ tem.11 Reichart and Quast12 did not rule out environmental factors such as presence of infection during the tooth development,

The consensus of opinion is that taurodontism results as a failure of the infolding of epithelial root sheet of Hertwig. Goldstein13 postulated that the lack of bridge formation in the root diaphragm of furcated teeth prior to the dentin deposition results in large pulp chambers. Taurodontism may be found occurring concomitantly with other abnor­ malities such as trico-dento-osseous syndrome,14 amelogenesis imperfecta, ectodermal dysplasia,15 Mohr syndrome,16 and Kline Felter's syndrome.17
The peculiar morphology of the pulp chamber may pose a challenge to the endodontist. Shafer18 has advocated vital pulpotomy rather than pulpectomy in endodontically involved teeth due to the pre­ sence of large pulp tissue mass.

A taurodont does not exhibit any unique morphologic clinical characteristics which may aid in its recognition. The radiographic examination is the only way to visualize a rectangular configuration of the pulp chamber. The apico-occlusal
height of the pulp chamber varies depending upon the type of taurodontism. The pulp chamber may extend to the apex of the tooth in hypertaurodon-tism and in that case the pulpal floor appears as a shelf in close proximity to the apices [Fig. 1). The apical extension may be mild to moderate in hypo- or mesotaurodontism [Figs. 2, 3|. The criterion for assigning a particular type in a given case is subjec­ tive. The taurodonts lack the cervical constriction of the pulp chamber seen in cynodonts. As men­
tioned earlier, the condition is rarely seen in primary molars [Fig. 41. The pulpal calcification may totally obliterate the pulpal space with age.19

The radiographic appearance of taurodonts should be differentiated from other conditions which may demonstrate enlarged pulp chamber.
The "shell teeth" of dentinogenesis imperfecta (Brandywine type) have large pulp chambers resulting from the relative absence of dentin. The teeth exhibit normal furcation but smaller root lengths. The teeth in regional odonto dysplasia, "ghost teeth", characteristically have very thin enamel and dentin and a large pulp chamber. The hard dental tissues will show qualitative and struc­ tural deficiencies and the teeth usually fail to erupt. In hypophosphatasia the teeth are hypocalcified and harbour large pulp chambers. The teeth get lost prematurely because of cemental agenesis.
The dentinal dysplasia type 2 shows large flame-shaped pulp chambers especially in premolars. The pulp horns rather than the pulp chamber are elongated in hypophosphatamia or vitamin D resistant Rickets. Pseudo-hypoparathyroidism exhibits teeth with enlarged root canals with lack of apical closures. Internal resorption of teeth may also pro­ duce larger pulp chambers due to loss of pulpal dentin.

From the review of literature, it is apparent that taurodont molars which are presumed characteris­ tic of neanderthal man, are still present as a morphological entity in modern man. The occurrences, however, seem to have a biased racial expression in mixed groups of Australoids and an ethnic bias relatively common in hybrids of Bush people, as well as mongoloid and negroid populations. In Caucasians, it is, however, a rare phenomenon. Identification of the condition can only be made by radiographic examination as the external morphology of the teeth is within normal configurations. The differential diagnosis between taurodontic teeth and other teeth exhibiting large pulp chambers can be of significance. In taurodonts the enamel and dentine thickness is within the normal range. Routine operative procedures can be performed without fear as long as quality tooth conservation is observed.

It has been stated that root canal therapy, espe­ cially in cases of hyper- and mesotaurodontism, could prove difficult and the endodontic therapy of choice in these situations should be conservative.u There is no literature report on the suitability of these teeth as bridge retainers. The lack of a cervi­ cal constriction would deprive the tooth of the but­ tressing effect against excessive loading of the crown.    Likewise,    if   conventional   root   canal therapy has been carried out, the use of intra-radicular posts is contraindicated.

In conclusion, taurodontism exist in modern man, possibly as a genetically linked trait.