title: Effectiveness of two intracanal dressings in adult Portuguese patients: a qPCR and anaerobic culture assessment.
abstract: OBJECTIVE
  To quantify bacterial equivalents before and after chemomechanical preparation using 3% sodium hypochlorite (NaOCl) and intracanal dressing with calcium hydroxide paste (Ca(OH)2 ) or 2% Chlorhexidine digluconate gel (CHX) in necrotic pulps associated or not with apical periodontitis and to further compare this quantification with counts of anaerobic microorganisms.
  
  
  METHODS
  Prospective clinical trial in 69 single-rooted adult teeth (strict inclusion criteria); CHX group: 34; Ca(OH)2 group: 35. Bacteria samples were taken at baseline (S1), after chemomechanical preparation (S2) and after 14 days of intracanal dressing (S3). Bacterial equivalents were assessed by broad-range real-time polymerase chain reaction (qPCR), and live viable bacteria measured with conventional anaerobic culture (CFU/mL). Descriptive/inferential analysis was performed with spss vs. 20.0 (α = 0.05) using the Kruskal-Wallis, Mann-Whitney and chi-squared tests and Spearman's correlation coefficients.
  
  
  RESULTS
  Both groups showed a significant decrease between S1 and S2 (Mann-Whitney U-test; P < 0.001) both in qPCR and in culture. In the Ca(OH)2 -group, no variation was observed between S2 and S3 by qPCR and culture. In contrast, the CHX group showed a significant increase from S2 to S3 by both techniques. The two groups were only significantly different in S3 (Mann-Whitney U-test; P ≤ 0.001), with a worse performance in the CHX group. Again, these results were congruent by both approaches. Data from both approaches correlate reasonably (rS < 0.5).
  
  
  CONCLUSIONS
  Infected root canals contained a high bacterial load, and the chemomechanical root canal preparation reduced bacterial equivalents by 99.1% and anaerobic counts by 98.5%. Intracanal dressings were not efficient at reducing bacterial load, but the 14-day intracanal dressing with Ca(OH)2 performed significantly better than CHX, particularly in cases with apical periodontitis.
authors: Health Sciences Faculty, Fernando Pessoa University, Oporto, Portugal; Abel Salazar Institute for the Biomedical Sciences, Oporto University, Oporto, Portugal.
authors: A M
authors: AM
authors: Teles
authors: M C
authors: MC
authors: Manso
authors: S
authors: S
authors: Loureiro
authors: R
authors: R
authors: Silva
authors: I G C
authors: IG
authors: Madeira
authors: C
authors: C
authors: Pina
authors: J M
authors: JM
authors: Cabeda
mesh_terms: D000328:Adult; D001421:Bacteria, Anaerobic / Q000235:genetics / Q000302:isolation & purification*; D001458:Bandages; D015169:Colony Count, Microbial; D004275:DNA, Ribosomal / Q000235:genetics; D003786:Dental Pulp Cavity / Q000382:microbiology*; D006801:Humans; D011174:Portugal; D011446:Prospective Studies; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012390:Root Canal Therapy
chemical_list: D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S
keywords: apical periodontitis; endodontic microbiology; intracanal dressing; qPCR; real-time PCR; root canal sampling