2007 Volume 28 Issue 3 Pages 161-171
Abstract : In the middle of the occlusal surface of human premolars, occasionally the so-called central cusps (dens evaginatus) have been noted. Because the occlusal anomalous tubercle can possess its own pulp chamber, pulpitis and its sequelae can result from fracture or splitting through mastication.
The patient was a 9-year-old Japanese boy in good health who had non-vital incompletely formed funnel shape roots of the lower second premolars with unilateral buccal swelling and internal dental fistulae. The tubercles gave the teeth a volcanic appearance. Radiographs showed a large periapical rarefaction over the areas of these teeth. Clinical diagnosis of these teeth was chronic suppurative apical periodontitis associated with the abnormal cusps. The endodontic challenges were successfully treated by apexification of the immature involved teeth using FR-Ca paste.
The occlusal anomalous tubercles were removed by the air turbine technique. These materials were fixed in 10% formalin solution. The decalcified sections of the tubercles were examined histopathologically. These cusps had slender pulp horns extending towards the pulps. In the pulp horn areas, pulp necrotic debris was seen. Displacement of cellular breakdown products was often seen within the dentinal tubules. Bacteria must have gained entrance to the pulp via the patent dentinal tubules.
Endodontic treatment of two affected premolars was performed by isolation with a rubber dam and surface disinfection. Root canal debridement and preparation by large K-files or H-files were employed. Instrumentation was done carefully to slightly short of the radiographic apex using a circumferential filing motion under copious canal irrigation with 6% sodium hypochlorite following by 3% hydrogen peroxide alternately into the canal. The canals were dried with large sterile cotton rolled on a broach.
FR-Ca paste was introduced with a Lentulo filler and a flat gutta-percha master cone, and also condensed with a large plugger.
The presence of apical calcific barrier was examined with radiographs, touch by canal instruments, an electronic impedance meter (Komatsu) and a Canalscope® (Osada Electric Co).
Apical calcific tissue replica was observed with a scanning electron microscope. An apical closure had apparently occurred from 6 months to 2 years later on the left premolar. The canal was obturated with gutta-percha using a lateral condensation technique. On the right premolar, apical healing has not progressed with a broader periapical pathosis after 6 years radiographically. There was an obvious reason for this failure : the canal space had not been thoroughly filled. Therefore this tooth was reopened, and the FR-Ca was washed out and repacked. Although FR-Ca paste extruded apically too much, there were no apparent long-term adverse effects. SEM photographs showed that even in the inner surface of the apical complete calcific barrier (hard tissue bridging) there were indentations, convexities, and other irregularities with the presence of small holes and coalescence structure.
