Micro-CT evaluation of apical enlargement of molar root canals using rotary or reciprocating heat-treated NiTi instruments

Abstract Objective The aim of this study was to evaluate the root canal preparation and apical enlargement of molar root canals with rotary or reciprocating heat-treated nickel-titanium (NiTi) instruments, by using micro-computed tomography (micro-CT). Methodology Mesial root canals (n=48) of mandibular molars, with a curvature between 20° and 40°, were prepared with ProDesign Logic (PDL) 25.01 and 25.06 in rotary motion, or ProDesign R (PDR) 25.06 in reciprocating motion (PDR). Apical enlargement was performed with PDL35.01 and PDL35.05 or PDR35.05. Scanning with 9 µm resolution was performed before and after preparation, and, after apical enlargement, by using micro-CT. The percentage of volume increase, debris and untouched root canal surface, transportation, centralization and preparation time were analyzed. ANOVA and Tukey or Kruskall-Wallis and Dunn statistical tests were conducted (α=.05). Results PDL promoted a higher apical percentage of volume increase, and lower percentage of debris and untouched root canal surface than PDR 25.06 preparation in entire canal and in all thirds (P<.05). Apical enlargement with PDL 35.05 and PDR 35.05 produced a higher percentage of volume increase in the apical region in relation to the initial preparation (P<.05). PDR 35.05 and PDL 35.05 showed similar results in relation to percentage of debris and untouched root canal surface in entire canal and in all thirds (P>.05). Centralization and transportation showed no difference (P>.05). PDR required less time to perform preparation and apical enlargement (P<.05). Conclusions The apical enlargement 35.05 with CM heat-treatment instruments using reciprocating and rotary motion reduced the percentage of debris and untouched root canal surface, without causing deviations or procedural errors. The protocol of greater apical enlargement favors the cleaning of the root canals in both kinematics. Preparation by the reciprocating system was faster than by the rotary system.

Atividade antimicrobiana residual de pastas base de hidr¢xido de c lcio e associa‡ães como medica‡Æo intracanal / Residual antimicrobial activity of calcium hydroxide based pastes and associations as intracanal medication

A resistˆncia do biofilme endod“ntico pode requerer um per¡odo maior de permanˆncia da medica‡Æo intracanal a fim de prolongar sua a‡Æo antimicrobiana. O objetivo deste estudo foi avaliar a a‡Æo antimicrobiana residual das medica‡ães intracanal: G1) hidr¢xido de c lcio + soro; G2) Calen; G3) Calen + PMCC; G4) Calen + clorexidina 0,4% e G5) clorexidina gel 2% frente … Enterococcus faecalis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus e Kocuria rhizophila em 60 canais radiculares bovinos. Os canais radiculares foram instrumentados e preenchidos com as medica‡ães intracanal, as quais foram removidas ap¢s os per¡odos experimentais (15, 30, 60 e 90 dias) e empregadas na t‚cnica de difusÆo em  gar. Os halos de inibi‡Æo foram evidenciados por gel de TTC e entÆo mensurados. Os dados de halos de inibi‡Æo foram submetidos … an lise estat¡stica dos testes Kruskall-Wallis e Dunn, com n¡vel de significƒncia de 5%. O Ca(OH)2 + soro apresentou efeito at‚ o per¡odo de 15 dias. A pasta Calen demonstrou efeito residual aos 60 dias frente ao S. aureus, enquanto Calen/ PMCC at‚ o per¡odo de 90 dias frente …S. aureus eK. rhizophilae aos 30 dias paraE. faecalis. A pasta Calen associado … clorexidina foi efetiva frente … E. faecalis at‚ o per¡odo de 60 dias. A clorexidina gel 2% apresentou a‡Æo residual em todos os per¡odos, com exce‡Æo de E. faecalis aos 90 dias, tamb‚m apresentou atividade antimicrobiana mais prolongada, seguido das associa‡ães do hidr¢xido de c lcio com clorexidina e PMCC.

The endodontic biofilm resistance requires a longer period of intracanal medication to promote antimicrobial action. The aim of this study was to evaluate the residual antimicrobial activity of intracanal medications: G1) calcium hydroxide + saline; G2) Calen; G3) Calen+PMCC; G4) Calen + chlorhexidine 0.4% and G5) chlorhexidine gel 2% against Enterococcus faecalis, Candida albicans, Pseudomonas aeruginosa, Staphylococcus aureus, and Kocuria rhizophila. Root canals from 60 bovine teeth were instrumented and filled with intracanal medications. After the experimental periods (15, 30, 60 and 90 days), intracanal medications were removed and they were evaluated using the agar diffusion technique. The inhibition zones were detected by TTC gel and then measured. Data from inhibition zones were analyzed statistically by Kruskal-Wallis and Dunn test, with a significance level of 5%. The Ca(OH) 2 + saline showed residual effect limited to a period of 15 days. The Calen had residual effects at 60 days against S. aureus, while Calen + PMCC were observed until 90 days against S. aureus, K. rhizophila, and 30 days for E. faecalis. The Calen paste associated to chlorhexidine was effective against E. faecalis up to 60 days. The gel chlorhexidine 2% had residual action in all periods, except for E. faecalis for 90 days, and it has more prolonged antimicrobial activity, followed by the associations of calcium hydroxide with chlorhexidine and PMCC.