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I 09 case report _ open-apex retreatment I roots4_2010 fully retrieved through the wide-open apex with the indispensable aid of a surgical microscope. Modified Hedstrom Files proved very useful for the purpose. Cleaning of the wide-open canal was enhanced by ultrasonic irrigation, while Ca(OH)2 was placed as an intra-canalmedicament.TheeffectivenessofCa(OH)2 as an antimicrobial agent is well documented,11 although its use is still controversial. Hachmeister et al.12 demonstrated that the remains of Ca(OH)2 on canal walls has no significant effect on MTA leakage or displacement resistance. On the other hand, it was suggested by Porkaew et al.13 that remnants of Ca(OH)2 on the dentinal walls may interfere with the apical seal produced. However, in a recent paper by Ham et al.,14 it was suggested that the combination of MTA and Ca(OH)2 in apexification procedures may result in more favourable regeneration of the peri- apical tissues. In the present case, Ca(OH)2 was removed as effectively as possible from the dentinal wallsusingultrasonicirrigationwith4.8%NaOCland 17% EDTA for one minute. For proper and safe adaptation of the MTA apical barrier,anabsorbablegelatinespongewascondensed attheapex,creatingascaffoldagainstwhichtheMTA materialcouldbeseated.SPONGOSTANisconsidered tobefullyabsorbedwithinfourtosixweeks(instruc- tion for the material use), while in the orthopaedic literatureitisreferredtoasapossible3-Dscaffoldfor a chondrocyte matrix.15 Concerns have been raised about delayed healing patterns and painful reaction to SPONGOSTAN when packed to sockets after surgi- cal removal of third molars.16 In the case of an open apex and MTA plugs combined with the use of ab- sorbable gelatine sponges, I have never encountered an experience of painful post-operative reaction or healing impairment attributed to the use of the gela- tinesponge.Furtherresearchisneededonthesubject. Fortheinsertionofthematerialinsidethewidecanal, asmallamalgamcarrierwasusedinconjunctionwith appropriate Schilder pluggers under magnification. Concerns have been raised about the MTA placement technique. Lawley et al.17 found that ultrasonic con- densation led to significantly less bacterial penetra- tion compared to hand condensation, after 45 days but not in the 90-day interval. On the contrary, Aminoshariaeetal.9 foundbetteradaptationandless radiographicvoidswithhandcondensationthanwith ultrasonics.Moreresearchisrequiredtofindtheideal placement technique. Appropriate adaptation of the material was assessed visually under microscopic inspection and radiologically. Concerns have been raised about the appropriate MTA plug thickness. It has been postu- latedbysomeauthorsthatthethicknessoftheapical plug may influence its leakage patterns. De Leimburg etal.18 reportedinarecentpaperthatorthogradeuse of MTA provided an adequate seal against bacterial infiltration, regardless of the thickness of the apical plug. Hachmeister et al.12 underlined in their paper that the thickness of the apical plug may have a significant impact only on displacement resistance. In the present case, we obtained a sufficient apical plug of 5mm, leaving 12mm space for resin post and core restoration. Orthograde delivery of MTA in open apices is con- sidered a very sensitive technique and the clinician shouldpractisehis/herskillsbeforegoinginvivo.This casepresentationwasdesignedtoguidetheclinician step-by-step to the successful management of chal- lenging open-apex cases._ Editorial note: A list of references is available from the publisher. Dr Antonis Chaniotis graduated from the University ofAthens Dental School in 1998.He completed a three-year postgraduate programme in Endodontics at the University ofAthens Dental School in 2003.He is a clinical instructor in the undergraduate and postgraduate programmes in the Department of Endodon- tics of the University ofAthens Dental School.Since 2003,he has practised in a private practice inAthens that specialises in Endodontics.Dr Chaniotis can be contacted at antch@otenet.gr or via his website www.endotreatment.gr. _about the author roots Fig. 6dFig. 6c Figs. 6a & b_Post-op radiograph and microscopic appearance of the MTA plug (x16, Global Entrée Plus). Figs. 6c & d_Gutta-fishing at 6 months. Fig. 6a Fig. 6b