I research _ working length Fig. 7a Fig. 7b Fig. 7c Figs. 7a–c_Less than half of teeth have single constriction (a) and the remainder have either multiple (b) or no constriction at all (c). considered and recommended to be the ideal physiological apical limit of the WL. However, since it is impossible to determine it clinically, many refer to this as a myth. The next anatomical challenge for the practitioner is the apical constriction. It has been proven that the CDJ and the apical constriction are two separate points and almost never coincide. The apical constriction is always located coronally to the CDJ (Figs. 6a & b). While the apical foramen is easily visualised in root canals microscopically, no well-defined apical constriction has been clearly confirmed. Less than 50 % of teeth display the points that could be regarded as the apical constriction. Figs. 8a & b_The less tissue to heal, the better the cure: X-ray control after 12 months (a); healing with cemental bridge (b). Figs. 9a & b_The apical terminus at the physiological foramen: X-ray after 12 months (a); optimal healing (b).16 Several authors have pointed out and classified variations in the topography and position of the apical constriction. Unfortunately, this knowledge cannot be consistently applied as less than half of the teeth have single constriction; the remainder have either multiple or no constriction at all (Figs. 7a–c). The distance from the apical constriction to the apical foramen ranges from 0.07 to 1.76 mm. Consequently, the distance from the apical constriction to the radiographic apex ranges from 0.75 to 4 mm. The following statements properly summarise this section on anatomy. Determining the apical foramen as the reference point gives more consistency than the apical constriction or radiographic apex.7 The use of the major foramen is more reproducible for accuracy studies.8 We can therefore conclude that owing to numerous inconsistencies, variations and ‘ifs’ with regard to the apical constriction and CDJ and their interrelationship, the apical foramen may be a more useful and reliable apical reference point in determining WL. The pathological and microbiological status of the dental pulp and peri-apical tissues is an extremely important decision-making factor for where, when, why and how to locate the apical terminus. In cases of vital and healthy or irreversibly inflamed pulp, free of bacteria or bacteria limited to the pulp chamber, there are two standpoints. One firmly suggests that pulpectomy is the treatment of choice in cases in which the apical terminus is located at the physiological foramen (Figs. 8a & b). We utilise this method, which is widely accepted amongst a majority of dental schools and practitioners in Europe, in almost each case, in following the basic biological and medical principle for any wound: the less tissue to heal, the better the cure.1 For the same pulp conditions, the second standpoint advocates partial pulpectomy in cases in which the apical terminus is located short of the constriction at a variable distance that can range from 1.5 to 10.0 mm short of the apex, leaving a pulp stump. Dressed and sealed appropriately with bio-compatible material, its vitality is preserved, enabling the pulp to continue with what it does the best: forming mineralised dentine tissue. Fig. 8a Fig. 8b Fig. 9a Fig. 9b 32 I roots 4_ 2009