Advances in technology have improved the use and quality of
tooth-canal instrumentation. Available irrigants such as NaOCl, chlorhexidine,
EDTA, and MTAD provide antibacterial, tissue solvent, and smear-removing
capabilities that aid in cleaning the root canal system of tissue remnants,
bacteria, bacterial products, and dentinal debris. In spite of this, root
canals with nonvital pulps often retain viable bacteria after instrumentation (Figure 1).1,2
The complexity of the root canal system and the inability of instruments
or irrigants to eradicate all bacteria contribute to this result. To decrease
the bacterial count in teeth of patients whose treatment plans include a series
of appointments, a wide range of materials have been sealed in the tooth
between appointments as intracanal medicaments.
A number of volatile aldehydes and phenolic compounds, such
as formocresol, camphorated parachlorophenol (CMCP), and cresatin, have been
promoted for years as intracanal medicaments. They were usually applied on a
cotton pellet and sealed within the pulp chamber. Although these materials
posses obvious antibacterial qualities in vitro, their clinical efficacy has
not been finalized conclusively. Because they are volatile in nature, the
duration of these materials is limited,3 and the potential exists
for a spread into the body.4,5 As a result, there is little emphasis
on the use of volatile medicaments.
Currently, calcium hydroxide is the most commonly used
intracanal medicament. It can be prepared as a paste by mixing calcium
hydroxide powder with sterile water, saline, or anesthetic. Commercially
available preparations are also available, which contain glycerine or methyl cellulose
to give a viscosity suitable for delivery into the canal (Figures 2-3-4-5-6).
Calcium hydroxide pastes may be placed into the canal by
injection, the use of pluggers, or with a lentulo spiral. Placement to the full
length of the canal is important to maximize the effects of the calcium
The pH of calcium hydroxide mixed with saline is 12.56.
This high pH is believed to contribute to its antibacterial and biologic
effects. Using calcium hydroxide as an intracanal medicament for one week has
been proved to substantially decrease the bacterial count as compared with
canals instrumented in the same way but without the use of calcium hydroxide.7
Endotoxin is a component of the cell wall of gram-negative
bacteria, which is released upon cell death and has been shown to be a potent
initiator of inflammation. Calcium hydroxide can hydrolyze the endotoxin
molecule, and it has been suggested that this neutralization of its
inflammatory effects may be an important benefit to using calcium hydroxide as
an intracanal medicament.8 Other evidence has shown that calcium
hydroxide is also capable of removing tissue remnants that may remain on canal
walls after instrumentation.9 This may aid in providing a cleaner
canal for obturation.
(Continued from page 1 )
Chlorhexidine gluconate is an antibacterial material that
has been used for years as an oral rinse for plaque control and has more
recently received support as an endodontic irrigant and intracanal medicament.
Chlorhexidine is less effective against gram-negative bacteria than it is
against gram-positive bacteria; there is one gram-positive specie, Enterococcus faecalis, that has
frequently received attention as being isolated from persistent infections
associated with previously root-filled teeth. Chlorhexidine has proven superior
for in vitro antibacterial effectiveness against E. faecalis as compared with calcium hydroxide; the in vivo
comparisons are less conclusive.10
Chlorhexidine is noted for its substantivity, in which its
antibacterial effects persist for days or perhaps weeks after placement. This
is due to its affinity for and slow release from the hydroxyapatite of dentin.
As an intracanal medicament, chlorhexidine can be used as a 2% liquid or gel.
The increased viscosity of the gel is thought to aid in its adaptation to the
canal walls and provide a more persistent effect. Delivery of chlorhexidine gel
can be performed with a file or lentulo spiral.
While a variety of intracanal medicaments are currently
available for use during endodontic procedures, selection of the appropriate
materials should be based on the material’s predictability, the patient’s
condition, and the operator’s comfort with the material’s delivery method. It
is imperative that an antibacterial agent be applied immediately following instrumentation
to limit the growth of microorganisms within the canal and to reduce the
potential of bacterial activity following root canal treatment and crown
restoration. As in any other restorative procedure, the patient’s overall
medical background should be verified prior to the delivery of intracanal
medicaments in order to avoid potential side effects.
*This piece was adapted from an article written by Dr. Robert Scott Gatewood in the Winter 2007 edition of Endodontic Therapy Magazine. Dr. Gatewood is an associate professor and chairman of the department of Endodontics at the University of Mississippi Medical Center School of Dentistry.
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- McGurkin-Smith R, Trope M, Caplan D,
et al. Reduction of intracanal bacteria using GT rotary
instrumentation, 5.25% NAOCl, EDTA, and Ca9OH)2. J. Endod
H, Shepard C, Chen RS. The duration of effectiveness of root canal
medicaments. J Endod 1984;10(6):240-245.
G, Nishikawa I, Kawazoe S, Toda T. Systemic distribution of 14C-labeled
formaldehyde applied in the root canal following pulpectomy. J. Endod
FK, Messer HH. Systemic distribution of camphorated monochlorophenol from
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DG, Haasch GC, Gerstein H. The pH of local anesthetic/calcium hydroxide
solutions. J Endod 1985;11(6):264-265.
- Shuping GB, Orstavik D, Sigurdsson A,
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rotary instrumentation and various medications. J Endod
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R, Araki K, Suda H. Effect of calcium hydroxide on the dissolution of soft
tissue on the root canal wall. J Endod 1998;24(5):326-330.
A, Gonzalez AM, Pozos A. Et al. Bacterial quantification in teeth with
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