Filling ability of an orthograde mineral trioxide aggregate placement technique to simplify the subsequent surgical procedures: a computed microtomography study

Aim To compare the filling quality obtained with standard retrograde procedures with that of a technique with the potential to simplify the surgical manoeuvres, namely the orthograde placement of 6 mm of mineral trioxide aggregate (MTA) followed by the root-end resection after cement setting. Methodology Sample size was calculated referring to previously published data (a = 0.05; b = 0.20; d = 3.0; r = 1.5). Accordingly, 12 freshly extracted single-rooted teeth were selected and transversally cut to obtain 12 mm long roots. Roots with aberrant anatomy were discarded. After manual scouting and mechanical glide path establishment, canals were shaped with HyFlex instruments up to size 40, 0.04 taper. The roots were randomly assigned to an experimental group (n = 6), where MTA was placed with a carrier and compacted with manual pluggers up to 6 mm from the working length, or to a control group that entailed filling with the single cone technique (n = 6). After 24 h, the roots in the experimental group received backfilling with thermoplasticised gutta-percha and apical resection. In the control group, the roots were resected apically and underwent standard retrograde ultrasonic preparation and MTA filling. The formation of internal and external voids was quantified by means of a computed microtomographic analysis. The normality of the distribution and the equality of variance of the datasets were tested; afterwards, the groups were compared statistically with an independent sample t-test (P = 0.05). Results Void formation was minimal in both experimental and control groups, ranging from 0.00% to 4.42% of the canal volume. In the control group, the voids (1.88 1.49%) were mainly external and related to sealer porosities. In the experimental group, the voids (1.08 0.50%) prevalently accumulated inside the MTA mass and at the interface between MTA and gutta-percha. The differences between the groups were not significant (P = 0.244). Conclusions The orthograde placement of MTA followed by apical resection may constitute a valid alternative to the standard surgical practice to simplify the surgical phases in selected cases.