The role of apical size determination and enlargement in the reduction of intracanal bacteria

By Mickel AK, Chogle S, Liddle J, Huffaker K, Jones JJ

Date: 01/2007
Journal: JOE

Summary:

  • Purpose:  to evaluate methods of determining initial apical size and secondly to assess the MAF size according to the initial apical size and its effect on intracanal bacterial load. 
  • N= 100 single-rooted teeth decoronated at 14 mm from the apex. 

Materials/Methods:

  • Canals were contaminated with Enterococcus faecalis

  • Coronal preflaring using K-files #10-#30 and GG drills #2 -#4. Sequentially larger K-files were inserted to WL until first file to bind at the WL (FAB), canal was then instrumented in a crown-down fashion using Profile .04 (5.25%  NaOCl)). The first file to reach the WL was recorded as the crown-down file (CDF)

  • Samples were divided into 3 MAF size groups of CDF +1, +2, and +3. Samples prepared for SEM.

  • Positive and negative control groups (n=5 each)

Most highlighted Results:

1.the Crown Down File was demonstrated to be an average of 4 file sizes larger than FAB (P< .05).

2.The number of samples yielding a negative culture were significantly higher in the CDF + 3 group compared to the CDF + 1 group. ( larger apical preparation = less bacteria cultured)

More bacterial colonies were observed in CDF +1, whereas scattered cocci were obs

Clinical Significance:

  • CDF method may provide a more accurate way of determining the apical size where the master apical rotary file is estimated to be 4 file sizes larger than the initial hand file that binds to WL
  • larger apical preparation = less bacteria cultured, which may provide a useful guide for apical size preparation in necrotic cases.

 

The number of samples yielding a negative culture were significantly higher in the CDF + 3 group compared to the CDF + 1 group