IntematiMMl EiuMmtk ^eanul (1990) 23,40-45
Root canal anatomy of mandibular second molars. Partn C-shaped canals S. A. MANNING Department ofRestorative Dentistry, Faculty of Dental Science, Universityof Melbourne, Melbmme, Victoria, Australia Summary. The root canal anatomy af 19 dibular second molars with C-^aped canals was investigated by rendering the roots transparent and allowing the canal system to be observed by black ink infiltration. The presence of three root canals was most frequent, and lateral canals were found in all roots. Transverse anastomoses were found in 15 of the 19 roots. The apical foramen was most commonly situated awayfromthe apex, and apical deltas were found in 16 of the 19 roots. The Cshaped canals were found more frequently in Asians than in other racial groups (P < 0.02). The formation of C-shaped roots and their racial predilection is discussed. A case report of the root canal treatment of a C-shaped canal is included and suggestions are made concerning suitable procedures for use in root canal treatment of these complex canal systems. Introduction C-shaped roots and root canals were first
docutnented in 1908 (Keith 1913) and 1911 (Keith & Knowles 1911), after examination of the skeletal remains of members of the Neanderthal race. The mandibular second molar showed a C-shaped root and, on sectioning, a C-shaped root canal (Fig. 1). The roots and canal anatomy of these teeth was quite different to that found amongst so-called 'modem man'. These findings were cited in support of the argument that Neanderthal man was not a predecessor of modem man but a collateral species that had become extinct (Keith 1913). During investigations of the dentition of East Greenland Eskimos, Cshaped roots and root canals in mandibular second molars were observed (Pederson 1949). These findings disproved the theory that Neanderthal man was a species collateral to modem man, and it is now thought that the Correspondence: Mr S. A. Manning, 1 Lister House, 11-^12 Wimpole Street, London W1M7AB, UK. 40
Neanderthal race were predecessors of the Mongoloid race (Tratman 1950), which includes Asian populations. Indo-European teeth were compared with teeth from Asians of Malaysia, and a number of differences were noted, including the finding of G-shaped roots and root canals in many mandibular second molars (Tratman 1950); also noted was a third root in mandibular first and third molars. Teeth with C-shaped roots were originally classified as taurodents. The term taurodontism was invented in 1913 (Keith 1913) to liken teeth with C-shaped roots to those seen in cud-chewing animals (taurus is the Latin word for 'bull'). The definition of teeth that fit this description has since been changed. The shape and number of roots is determined by Hertwig's epithelial sheath, which bends in a horizontal plane below the ameiocemental junction and fuses in the centre leaving openings for roots (Orban & Mueller 1929). Fused roots may form either by coalescence due to cementum deposition with time, or as a result of failure of Hertwig's epithelial sheath to develop or fuse in the furcation area (Pederson 1949). Failure to fuse on the buccal aspect would result in formation of a groove on the lingual aspect, and failure to fuse on the lingual would give a buccal grove. Fusion failure on both the buccal and lingual aspects would result in formation of a conical or prism-shaped root. Investigations ofroot development in mouse molars showed that roots were formed by the meeting of dentine leaflets (Flschlschweiger & Clausnitzer 1988). The fusing of these leaflets was sometimes irregular, forming accessory catuls and occasionally, especially in the third molars, the leaflets failed to form. In the case of mandibular molars such failure of dentine leaflet formation resulted in a C-shaped root
Root canals ofmandibular second molars
41
B A'
A'"
Fig. I. Description of Neanderthal and modem English mandibuiar second molars (Keith & Knowles 1919): A, labial aspect of second lower molar of Brelade dentition (Jersey); A', its chewing surface; A", distal aspect; JK'", section of root; B, labial aspect ofthe same tooth of a modem English dentition; B', the distal aspect of the same. (This text is not covered by copyright and the authors are deceased.)
and canal. It was p
Root canal anatomy of mandibular second molars. Partn C-shaped canals S. A. MANNING Department ofRestorative Dentistry, Faculty of Dental Science, Universityof Melbourne, Melbmme, Victoria, Australia Summary. The root canal anatomy af 19 dibular second molars with C-^aped canals was investigated by rendering the roots transparent and allowing the canal system to be observed by black ink infiltration. The presence of three root canals was most frequent, and lateral canals were found in all roots. Transverse anastomoses were found in 15 of the 19 roots. The apical foramen was most commonly situated awayfromthe apex, and apical deltas were found in 16 of the 19 roots. The Cshaped canals were found more frequently in Asians than in other racial groups (P < 0.02). The formation of C-shaped roots and their racial predilection is discussed. A case report of the root canal treatment of a C-shaped canal is included and suggestions are made concerning suitable procedures for use in root canal treatment of these complex canal systems. Introduction C-shaped roots and root canals were first
docutnented in 1908 (Keith 1913) and 1911 (Keith & Knowles 1911), after examination of the skeletal remains of members of the Neanderthal race. The mandibular second molar showed a C-shaped root and, on sectioning, a C-shaped root canal (Fig. 1). The roots and canal anatomy of these teeth was quite different to that found amongst so-called 'modem man'. These findings were cited in support of the argument that Neanderthal man was not a predecessor of modem man but a collateral species that had become extinct (Keith 1913). During investigations of the dentition of East Greenland Eskimos, Cshaped roots and root canals in mandibular second molars were observed (Pederson 1949). These findings disproved the theory that Neanderthal man was a species collateral to modem man, and it is now thought that the Correspondence: Mr S. A. Manning, 1 Lister House, 11-^12 Wimpole Street, London W1M7AB, UK. 40
Neanderthal race were predecessors of the Mongoloid race (Tratman 1950), which includes Asian populations. Indo-European teeth were compared with teeth from Asians of Malaysia, and a number of differences were noted, including the finding of G-shaped roots and root canals in many mandibular second molars (Tratman 1950); also noted was a third root in mandibular first and third molars. Teeth with C-shaped roots were originally classified as taurodents. The term taurodontism was invented in 1913 (Keith 1913) to liken teeth with C-shaped roots to those seen in cud-chewing animals (taurus is the Latin word for 'bull'). The definition of teeth that fit this description has since been changed. The shape and number of roots is determined by Hertwig's epithelial sheath, which bends in a horizontal plane below the ameiocemental junction and fuses in the centre leaving openings for roots (Orban & Mueller 1929). Fused roots may form either by coalescence due to cementum deposition with time, or as a result of failure of Hertwig's epithelial sheath to develop or fuse in the furcation area (Pederson 1949). Failure to fuse on the buccal aspect would result in formation of a groove on the lingual aspect, and failure to fuse on the lingual would give a buccal grove. Fusion failure on both the buccal and lingual aspects would result in formation of a conical or prism-shaped root. Investigations ofroot development in mouse molars showed that roots were formed by the meeting of dentine leaflets (Flschlschweiger & Clausnitzer 1988). The fusing of these leaflets was sometimes irregular, forming accessory catuls and occasionally, especially in the third molars, the leaflets failed to form. In the case of mandibular molars such failure of dentine leaflet formation resulted in a C-shaped root
Root canals ofmandibular second molars
41
B A'
A'"
Fig. I. Description of Neanderthal and modem English mandibuiar second molars (Keith & Knowles 1919): A, labial aspect of second lower molar of Brelade dentition (Jersey); A', its chewing surface; A", distal aspect; JK'", section of root; B, labial aspect ofthe same tooth of a modem English dentition; B', the distal aspect of the same. (This text is not covered by copyright and the authors are deceased.)
and canal. It was p
