A survey conducted in 2005, indicated an increased number of paediatric dentists were using the 1-appointment IPT technique in the United States compared with a 1997 survey[23]. In our study, the CH-IPT and 3Mix-MP overall success rates at the 12–29 month recall were 94% and 78%, respectively. These results are consistent with previous studies where the success rates of IPT with follow-up periods from 3 months–7 years ranged from 84–100% regardless of the type of base material or final restoration[4-9, 24-27]. The slightly lower success rate in our study may have resulted from inclusion criteria that accepted only mandibular

primary molars in which the diagnosis of pathology is easier compared with the maxillary teeth where overlapping permanent tooth buds can complicate their evaluation. Other studies included

maxillary and mandibular primary molars[4, 5, 7, 8, 24, selleck inhibitor 25] and some included both primary and permanent molars[6, 27]. Our data indicate that both techniques yielded similar success rates. Marchi et al.[24] found that the most frequent cause of IPT failure at the 6–12 month follow-up was the clinical observation of a fistula (2 of 27 teeth; 7.41%), suggesting misdiagnosis of the pulpal condition. In contrast, we did not find any clinical signs or symptoms of irreversible pulpitis or pulp necrosis at our 6–11 month recall. We did find a fistula or abnormal mobility in two teeth in the 3Mix-MP DAPT group at the 12–29 month recall. In our study, almost all findings of overall failure

resulted from radiographic failure except in one tooth in the 3Mix-MP group that was a clinical failure (abnormal mobility) but exhibited radiographic success with canal obliteration. Most of our findings are consistent with Farooq et al.[7] who found all clinical failures exhibited radiographic failure, but not all radiographic failures had clinical signs and symptoms. In our study, bifurcation or inter-radicular radiolucency was the Ribonucleotide reductase most frequent failure seen at the 6–11 month recall, whereas internal root resorption and bifurcation radiolucency were the most frequent failures observed at the 12–29 month recall. This finding is consistent with a previous study by Falster et al. in which the majority of their failures were from interradicular lesions noted at the 12–24 month recall, whereas internal root resorption was found in one tooth at the 18-month recall[4]. Precise radiographic and careful clinical diagnoses are essential to the high success rate of IPT. Pain and sensitivity are important clinical symptoms for proper diagnosis. It is difficult to obtain precise information related to these symptoms from children, however. Thus, parents, participation may help paediatric dentists more precisely make the pulpal diagnosis. The failures observed in our study could be explained by the difficulty in the diagnosis of pulpal status based on the child and parent’s report of symptoms.