Root Canal Obturation general concepts principles
-
Upload
deepthi-p-ramachandran -
Category
Health & Medicine
-
view
2.066 -
download
10
Transcript of Root Canal Obturation general concepts principles
Root canal OBTURATIONDEEPTHI P.R.II YEAR MDS
“Perhaps there is no technical operation in dentistry or surgery where so much depends on the conscientious adherence to high ideals as that of pulp canal filling.” -Hatton (1924)
Contents • Introduction• Definition• Challenges & Importance of sealing the root canal system• History• Timing• Preparation• Apical extent/ length• Longitudinal studies• Overfilling/ overextension• Ideal root canal filling• Evaluation of obturation• Errors• Summary
Introduction• The final objective of endodontic procedures should be the
total obturation of the root canal space• It is the sealing off of the complex root canal system from the
PDL & bone which insures the health of the attachment apparatus against breakdown of endodontic origin
• Key to success: The elimination of microorganisms & their by-products
Schilder.H. JOE — Volume 32, Number 4, April 2006
After disinfection, the obturation stage:• Fill the root canal- hermetic seal from the coronal orifice of
the canal to the apical foramen at the CDJ• The responsibility does not end here• Coronal seal- an integral part of endodontic treatment & vital
role in the treatment’s success
BRITISH DENTAL JOURNAL Volume 216 No. 6 MAR 21 2014
DEFINITIONS
Obturate—To fill the shaped and debrided canal space with a temporary or permanent filling material.Obturation technique—The method used to fill and seal a cleaned and shaped root canal using a root canal sealer and core filling material; sealers are frequently used as the sole obturating material in deciduous teeth; there are a variety of techniques used to obturate the canal space
Glossary of Endodontic Terms
Rationale, Objectives, Importance• Prevent the reinfection of root canals that have been
biomechanically cleaned, shaped and disinfected Successful obturation :• use of materials & techniques capable of densely filling the
entire root canal system • providing a fluid tight seal from the apical segment of the
canal to the cavo-surface margin in order to prevent reinfection.
Colleagues for Excellence. Fall 2009
Three main functions
1. Prevent coronal leakage of microorganisms or potential nutrients to support their growth into the dead space of the root canal system
2. Prevent periapical or periodontal fluids percolating into the root canals and feeding microorganisms
3. Entomb any residual microorganisms that have survived the debridement & disinfection stages of treatment, in order to prevent their proliferation & pathogenicity
BRITISH DENTAL JOURNAL VOLUME 216 NO. 6 MAR 21 2014
• Value of total obturation of the root canal system: important elements or judgement
1. The inability to know with certainty whether the apex has been sealed in a nonsurgical procedure
2. The existence of numerous accessory canals, many of which contain significant potential for the production of lateral root abscesses
Schilder.H. JOE — Volume 32, Number 4, April 2006
Challenges in obturation• A space whose parameters vary infinitely from root to root or
from tooth to tooth must be obliterated completely
Coronal cavity Root canal system
• Space can be visualized easily
• Margins of the cavity must be extended in certain ways to insure the removal of all carious dentin, to provide for the placement of a suitable filling, & to protect against redecay
• Filling must be most complete in regions beyond the visibility of the dentist
• Cavity form developed in cleaning & shaping root canals must provide for the removal of all organic debris, give good access to the foramina, & offer a shape conducive to the placement of a dense permanent root canal filling.
Importance of Effectively Sealing the RC System• Ingle & colleagues: 58% of treatment failures - incomplete
obturation• Often poorly prepared• Procedural errors• Correlation between the quality of obturation & nonhealing:
presence of bacteria – Fabricus et al.• Obturation may not influence the short-term success rates:
but in long-term studies if coronal leakage were to occur
Importance of Effectively Sealing the RC System• Cleaning & shaping determines: the degree of disinfection &
the ability to obturate the radicular space. • Reflection of the cleaning and shaping
• Not possible to assess the quality of the seal with a radiograph• No material or technique prevents • Porous tubular structure of dentin and canal irregularities
Obturation of the radicular space:• Eliminates leakage• Reduces coronal leakage & bacterial contamination• Seals the apex from the periapical tissue fluids• Entombs the remaining irritants in the canal
Importance of Effectively Sealing the RC System• Coronal leakage: treatment failure• Effective coronal seal and placing an appropriate restoration• Use a final restorative material versus a temporary material to
prevent leakage• Ray & Trope. (1995): Good postendodontic restorations (80% ) vs good endodontics
& poor restorations (75.7%) Prognosis for endodontically treated posterior teeth restored
with crowns was enhanced sixfold
• An adequate radiographic appearance : may not- adequate seal
• Variation in radiographic interpretation by the clinician• Overlying osseous structures• Lack of uniformity in the obturation materials
Historical Perspectives• Over 100 years• Edward Hudson in 1825: Filling with gold foil• Edmund Kells- first endodontic radiograph in 1899• “Hermetic seal” of the canal terminating at the
dentinocemental junction- Grossman’s Principle 9 in 1967• “Sealed against the escape or entry of air” or made ‘Airtight
by fusion or sealing’ – inaccurate• Hermes Trismegistus - seal of wax• Obturating the canal space: fluid leakage at the apex or the
coronal level. • ‘‘Impermeable seal’’• fluid-tight, fluid-impervious, or bacteria-tight seals
Historical Perspectives
• Various metals, ZnOCl, paraffin & amalgam • 1847- Hill developed the first GP root canal filling material:
“Hill’s stopping.”• Bleached GP, carbonate of lime and quartz: patented in 1848 • 1867- Bowman made claim : the first use of gutta-percha for
canal filling in an extracted first molar.
Historical Perspectives• Perry 1883- Pointed gold wire wrapped with some soft gutta-percha GP rolled into points & packed into the canalSaturated the tooth cavity with alcohol• 1887- S.S. White Company :manufacture GP points• 1893 Rollins introduced a new type of gutta-percha to which
he added vermilion
• Additional filling material : fill the voids• Hard-setting dental cements: unsatisfactory• Strong antiseptic action: phenolic or formalin-type paste
cements • Callahan (1914): softening & dissolution of the gutta-percha -
cementing agent• Various pastes, sealers & cements
Factors influencing complete obturation• Quality of the cleaning and shaping of the canal system• Skill and experience of the clinician• Materials and their usage• Restoration of the tooth• Health of the supporting periodontium
www.ineedce.com Root Canal Obturation: An update
Timing of Obturation
• RC system is dry and time permits, obturating at the same visit is recommended.
• If a dry root canal system not achieved: inter-appointment dressing.
• Asymptomatic• Mild/ significant symptoms: asymptomatic upon obturation
BRITISH DENTAL JOURNAL VOLUME 216 NO. 6 MAR 21 2014
• Negative bacterial cultures.• Sjogren et al. 5-year recall• 94% of cases - negative cultures: successful• 68% of those filled with positive cultures were successful• Procedural concerns• Difficult cases- multiple appointments• Medical conditions, psychologic state of mind, and fatigue.
Preparation for Obturation• Obturation materials designed to bond with dentin, irrigation
solutions must be used with consideration of the condition of the dentin surface that is most suitable for bonding
• Smear layer: slowly disintegrate & dissolve around leaking obturation materials
• Sealer penetration into dentinal tubules does not occur when the smear layer is present
Colleagues for Excellence. Fall 2009
• Increased bond strength and reduced microleakage in teeth obturated with AH-26
• Removal of the smear layer: adhesion of sealers to dentin & tubular penetration
• Clarke- Holke et al. 60% of the samples in which the smear layer was not removed demonstrated bacterial leakage. There was no leakage in specimens from which the smear layer was removed.
Preparation for Obturation• 17% disodium EDTA for one minute, followed by a final rinse
of sodium hypochlorite• Sonic and ultrasonic instrumentation• Mixture of a tetracycline isomer, an acid, and a detergent
(MTAD)• 50% HNO3
• Tetracycline• Concern: increased dentin permeability due to
demineralisation
LENGTH/ APICAL EXTENT OF OBTURATION• The totality of the 3D filling of the RC is more important than
its vertical extent alone• Disagreement where to terminate instrumentation and
obturation • Kuttler : Termination should be to the apical constriction,
when the apical constriction exists. • Seltzer et al. The reaction to tissues were milder when
instrumenting short of the apex as compared to instrumenting beyond the apex.
Schilder.H. JOE — Volume 32, Number 4, April 2006Schaeffer et al. JOE — Volume 31, Number 4, April 2005
LENGTH/ APICAL EXTENT OF OBTURATION• Most North American and European Schools: instrumentation
& obturation should be contained within the root canal (Cailleteau & Mullaney 1997)
• Weine: A point located 1mm coronal to the apex is close to the area of the CDJ; 1mm short of the radiographic apex-probably acceptable.
• Agreed with Kuttler's study (1955) which identified a smaller diameter or `apical constriction‘ as the point where the canal preparation should end and where the deposition of calcified tissue is most desirable.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Weine: Periapical radiolucency with radiographic signs of apical resorption, the preparation should be shortened by an additional 0.5mm from the radiographic apex.
• Suggested instrumentation & obturation to the CDJ, (1982) which he believed was located at the same level as the apical constriction
• Nguyen (1985) indicated the CDJ as the limit of the preparation
• Ingle (1973): Obturation at 0.5mm from the radiographic apex; obturating up to the radiographic terminus of the root actually results in an overfilling.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Frank et al. (1988) suggested an apical stop located between 0.5mm and 1mm from the apex
• Too much importance has been given to lateral & accessory canals; their importance is relatively little if the main canal is properly prepared and filled. Their obturation happens by chance & does not have clinical significance.
• Guldener (1985): A working length which corresponds to the tooth length less 0.5mm for cases with a necrotic pulp. In cases of vital pulp extirpation: an additional reduction of 0.5 mm, 1mm short of the tooth length.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Taylor (1988): a narrower spot at the apical level called `Minor Diameter' which he believed to correspond histologically to the CDJ
• Langeland (1957, 1967, 1987, 1995): termination of instrumentation & obturation at the apical constriction
• “The most frustrating clinical aspect is that no exact distance from the radiographic apex could be given, because the distance from the radiographic apex to the apical constriction varies widely from root to root”
• All endodontic sealers are irritant and resorbable (1974, 1995)
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
Langeland- 1996 • CDJ: histopathological structure which cannot be found
clinically and thus cannot be instrumented/ obturated. • Carefully study a high quality radiograph in a viewing device
blocking out all extraneous light• Have the knowledge of the variations of RC anatomy foremost
in your mind• Use your tactile sense to locate the apical constriction,
observe if blood or other tissue fluids appear on the instrument tip, or anywhere on a paper cone, indicating that you are in the periapical tissue.
• This is an inaccurate art, based on precise science.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
Langeland • Finally, put it all together using common sense• Instrumentation beyond the foraminal constriction causes an
unnecessary enlargement of the pulpal wound• Contaminants :wound healing • Medicaments and/or materials - tissue destruction,
inflammation, and a foreign body reaction in the periapical tissue'
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
LENGTH/ APICAL EXTENT OF OBTURATION• Pecchioni (1983) : “during instrumentation it is better not to
go nearer than 0.5±1mm from the radiographic apex”. • Obturation should end at 0.5mm from the radiographic apex• `. . . while it is very serious and damaging to go beyond this
limit with instrumentation, it is less serious to slightly overfill the apex, since the common sealers are generally tolerated and easily resorbable‘
• Weine (1982) suggested shortening the working length, Guldener (1985) suggested increasing it.
• An apical overfilling in necrotic cases has also been suggested Pecchioni (1983).
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
Schilder -1967, 1976• Debridement and obturation to the radiographic apex, which
often results in material being extruded into periradicular tissues
• 3 - 5% NaOCl solution completely removes necrotic organic debris
• Opposed limitation of preparation at the CDJ or at the apical constriction: too approximate to apply a mathematical or statistical formula (0.5, 1 or 2 mm).
• Schilder (1987) later requested that canal instrumentation and obturation should stop at the canal terminus
• Scianamblo (1989): RCs & ramifications can be effectively cleaned during cleaning and shaping if these systems are properly irrigated with NaOCl
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
LENGTH/ APICAL EXTENT OF OBTURATION• Green, Frank, & Stein advocated obturating short of the
radiographic apex (0.5–2.0 mm)• Walton, Torabinejad & Weine : obturating short of the
radiographic apex, and in the presence of root and/or bone resorption, preparation and obturation should be to even shorter lengths
Schaeffer et al. JOE — Volume 31, Number 4, April 2005
• Obturations 0 to 1mm short of the apex were better than obturations 1 to 3mm short of the apex
• Both were superior to obturations beyond the apex.• Obturating materials extruding beyond the radiographic apex
correlated with a decreased prognosis
Schaeffer et al. JOE — Volume 31, Number 4, April 2005
Cementodentinal Junction:• The point which divides the pulp tissue from the tissue of the
periodontal ligament.• Small distance within the apical end of the root canal and at a
somewhat constricted portion of the apical opening. • Fills the root canal without impingement on the periapical
tissues & encourages the eventual physiologic closure of the root canal with cementum.
Schilder.H. JOE — Volume 32, Number 4, April 2006
Cementodentinal Junction:
In order to fill to the CDJ:• sense of feel • fills all canals 0.5 to 1mm short in the hope of ending the root
canal filling properly. • Position of CDJ is highly variable
from one tooth to another & even from one wall to
the opposite wall of the same root.
Schilder.H. JOE — Volume 32, Number 4, April 2006
• The cementum may join the dentin 0.5mm inside the root on one surface, and 3 or 4 mm inside on the opposite surface
• CDJ may occur outside the RC completely.• Feeling for the apical constriction, very difficult for less
experienced operators.
Radiographic apex• The point where the root
canal appears to join the PDL as viewed in a roentgenogram• 100% total filling • Probably overextended
beyond the root • Markedly curved canals
exit their roots at a point which is invisible radiographically: such filling avoided
Schi
lder
.H. J
OE
— V
olum
e 32
, Num
ber 4
, Apr
il 20
06
• Success: filling RCs to their radiographic apices or beyond• Stimulation by RC filling material: healing• Continued success: Filling to the CDJ• Thoroughness of 3D filling along the major extent of the RC.
Schilder.H. JOE — Volume 32, Number 4, April 2006
Longitudinal studies• Strindberg (1956): 775 endodontically treated roots, reviewed
up to 10 years after treatment: the highest success rate -obturation terminated 1mm short of the radiographic apex
• Swartz et al. (1983): 1007 endodontically treated teeth, 1770 canals: ‘ overfilled canals were four times more likely to fail than canals filled short of the radiographical apex'.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Marin (1989): Retrospective analysis: 1200 roots treated over a period of 5 years: `cases with fillings at 0.5 and 1mm from the radiological apex appear to have a significantly superior clinical prognosis’
• Reaches or goes beyond radiological apex: decrease in the number of complete repairs and a consequent increase in incomplete repairs and failures
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Sjogren et al. (1990): roots with necrotic pulps & periapical lesions the best prognosis was obtained when the filling reached within 2mm of the apex (94%).
• Excess root filling: success rate decreased to 76%• Excess root filling during retreatment of previously filled
roots : 50%.• Smith et al. (1993): 86.95% success rate when the position of
the root filling was within 2mm of the radiographic apex• `Long' obturation : 75%• Friedman et al. (1995): Presence of extruded sealer the
success rate was 56.7% against 81.9% in the absence of extrusion.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
Anatomical evidence• Preiswerk (1903): First to describe the presence of an
anastomosing canal system• Hess (1917) : study of the anatomical complexity of the root
canal system.• Kuttler (1955) : impressive number of measurements on the
apical part of the canal
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Gutierrez & Aguayo (1995): 140 extracted permanent teeth with a SEM.
All the root canals- deviate from the long axis of their rootsThe number of foramina : 1 to 6The openings always ended short of the apices by 0.20±3.80
mm.Very seldom does a root canal end at the radiographic apex.
Ricucci.D. International Endodontic Journal (1998) 31, 384 -393
• Phenomenon: recognizable on the radiograph only when the foramen ends on the mesial or distal aspect of the root
• Cases of endodontic failure where the canal appeared to be filled short of the apex radiographically: obturated beyond the foramen.
• Langeland (1996): refused to settle for any particular length from the apex.
• The radiographic apex with all its radiographic inaccuracies is the `constant' against which the everchanging distance from the anatomical apical constriction must be measured: inaccurate
Ricucci.D International Endodontic Journal (1998) 31, 384 -393
Histological evidence• The first scientific basis for modern clinical endodontology was
established by Davis (1922)• On the basis of Hess's study (1917): first to suggest that
careful treatment of the apical tissue was a requirement for success in endodontics
• First histological studies on pulp wound healing were made by Hatton et al. (1928) & by Blayney (1929)
• Studies: Vital pulp treatment- partial pulpectomy was preferred to total pulp removal
Ricucci.D International Endodontic Journal (1998) 31, 384 -393
• The recommendation for the termination at the apical constriction is based on sound wound healing principles:
• Severance of the tissue creates the smallest possible wound; the less tissue to heal the better the cure.
• The patency technique by Buchanan (1989) violates this cure. • `Patency' means the use of `a small flexible K-file which will
passively move through the apical constricture without widening it'.
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
• Nygaard-Ostby (1939 & 1944): Better prognosis was obtained when that tissue was left undisturbed in vital cases
• Langeland (1987): demonstrated that undisturbed & uninflamed tissue also occurs in cases where there is necrosis in the canals
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
• Apical foramen: more often than not, >1 mm short of the radiographic apex
• Obturations 1 mm short of the radiographic apex are in fact in the periapical tissue creating a larger wound (Ricucci et al. 1990)
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
• Sealers & GP tissue destruction, inflammation & a foreign body reaction
• Oblique apex and the filling radiographically ends short on one side & is over-extended on the opposite side of the apex
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
• The filling beyond the apex : lowest prognosis. • Materials used are not biocompatible• Clinical failures could be observed even in the absence of
bacteria
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
Wise old suggestion :• Slightly underextend root canal fillings in cases of vital
extirpation • Fill to the radiographic apex or slightly beyond in cases of
pulpal necrosis and gangrene
Schilder.H. JOE — Volume 32, Number 4, April 2006
• Best prognosis for RCT : adequate instrumentation & homogeneous obturation to the apical constriction.
• Worst prognosis: instrumentation & filling beyond the apical constriction.
• Second worst prognosis: Obturation >2 mm short of the apical constriction, combined with poor instrumentation and obturation.
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
• The distance between the foramen & the apical constriction is often > 1 mm, e.g. 3 mm.
• Lateral canals and/or apical ramifications: (i) cannot be debrided mechanically or chemically (ii) when `filled', the injected material causes tissue destruction
and inflammation• Radiographic demonstration of them does not mean
excellence in endodontics
Ricucci & Langeland—International Endodontic Journal, 31, 394-409
Overfilling vs Overextension• Over and under extension refer solely to the vertical
dimension of the root canal filling, beyond or short of the root apex.
• Underfilled tooth : A tooth whose RC system has been inadequately obturated in any dimension, leaving large reservoirs for recontamination and infection.
• Underfilling—An incomplete obturation of the root canal space with resultant voids
Schilder.H. JOE — Volume 32, Number 4, April 2006Glossary of Endodontic Terms
• Overfilled tooth: One whose RC system has been filled in three dimensions,& where a surplus of material extrudes beyond the foramina
• Overfilling—A solid or semi-solid core root canal filling extending beyond the apical foramen; commonly used to imply that the root canal space is completely obturated.
• Overextension—A solid or semi-solid core root canal filling extending beyond the apical foramen, often the result of failure to create an apical stop during instrumentation; commonly used to imply that the root canal space is not completely obturated.
Schilder.H. JOE — Volume 32, Number 4, April 2006Glossary of Endodontic Terms
Schilder.H. JOE — Volume 32, Number 4, April 2006
Overfilling vs Overextension• No case of endodontic failure due to overfilling, ie. when the
root canal has been obturated in its entirety & surplus material has been intruded into the apical periodontium (prev. fig)
• Numerous cases of failure of vertical overextensions of underfilled root canals.
• GP or silver cones- carelessly forced into the apical periodontium
• Additional insult to the primary problem, namely the underfilled root canal.
Schilder.H. JOE — Volume 32, Number 4, April 2006
• Obturation: surrogate marker of how well the canal has been prepared and cleaned
• Judged by its taper, condensation & length• Aiming to provide a well condensed root filling ending just
coronal to the apical foramen is desirable and important
BRITISH DENTAL JOURNAL Volume 216 No. 6 MAR 21 2014
Ideal Root Canal Filling• Three-dimensionally fills the entire RC system as close to the
CDJ as possible• Shape reflecting a continuously tapered funnel: approx. the
same as the external root morphology• Radiographically: dense, 3D filling that extends as close as
possible to the CDJ
Root Canal Obturation: An update
Ideal Root Canal Filling• “ RC sealers are used in conjunction with a biologically
acceptable semisolid or solid obturating material to establish an adequate seal of the RC system”-AAE’s Guide to Clinical Endodontics
• “Paraformaldehyde-containing paste or obturating materials have been shown to be unsafe. Root canal obturation with paraformaldehyde-containing materials is below the standard of care for endodontic treatment”
Evaluation of obturation
The radiographic appearance of a completed case should show the obturation material: (1) At the apical terminus without excessive material
overextending into periapical tissues(2) Completely filling the root canal system in three dimensions(3) Appearing as a dense radiopaque filling of the root canal
system
Colleagues for Excellence. Fall 2009
Clinical evaluation• Normal findings to routine tests• Concerned about prognosis, the reevaluation visit should be
scheduled in a few weeks• Routine reevaluation periods: 6 months and 1 year. • If symptoms occur they should call the office for an
appointment
Colleagues for Excellence. Fall 2009
Radiographic evaluation• Length, Shape & Density• The length of an ideal fill should be from the canal’s apical
minor constriction to the canal orifice unless a post is planned. The core restoration- the cavo-surface margin.
• The shape of the completed case: obturation technique being used
• Voids should not be visible on the radiographic image• GP & sealer removal to the facial CEJ or the canal orifice in
posterior teeth• Adequate provisional restoration or definitive
Colleagues for Excellence. Fall 2009
Variability in radiographic interpretation• Differences in radiopacity in sealer/cements• Constituents in specific brands of GP• Interpretation of voids in vivo versus in vitro• Overlying bony anatomy• Radiographic angulation• Limited 2D view
Density of the apical portion of the fill: Highly radiopaque sealers/cementsApical portion filled only with sealer: the false impression of a dense,3D obturation with GP• Voids masked by the density of the sealer. • Radiopacity of selaer: claim to superiority- unfounded &
unwarranted. • Aesthetic appearance of the obturated canal system-
secondary to meticulous cleaning and shaping
In vitro methods• ‘Sealability’ of root canals following obturation: traditionally
tested by leakage studies.• Validity of these studies ???• The clinical implications for laboratory-based ‘sealability’
experimental models: unclear• Many leakage models are non-reproducible
BRITISH DENTAL JOURNAL Volume 216 No. 6 MAR 21 2014Int Endod J. 2012 Dec;45(12):1063-4
In vitro studies
Methods of microleakage evaluation• Dye penetration• Radioisotopes• Electrochemical• Fluorometrics• SEM
• Root clarification
• Fluid filtration
• Fluid transport
• Proteins
• Endotoxins
• Glucose penetration
Leakage
Coronal leakage Microorganisms from the oral cavity that penetrates the whole root canal system to eventually trigger a host reaction in the apical periodontium.
Apical leakageInfiltration of the apical root segment by peptides and other molecules, which have the potential to support microbial metabolism in the filled root canal system
International Endodontic Journal, 44, 183–194, 2011
Issues in research• Anatomy of the RC system: main confounding factorUse paired teeth• Routes of microbial leakage -traced histologically to validate
the two-chamber model• RC sealer penetrating into dentinal tubules: not indication of
superior root filling technique or material
Int Endod J. 2012 Dec;45(12):1063-4
Two-chamber system• Tooth sealed in between the upper & the lower chamber. • Turbidity or a colour reaction in the originally sterile broth in
the lower chamber Leakage of viable microorgansims• Bacterial leakage around fillings (Mortensen et al. 1965)• Endodontics: Goldman et al. 1980
International Endodontic Journal, 44, 183–194, 2011
Possible reasons• More sensitive than histology• Inherent problem with the set-up: the assumption that
leakage should occur through the RC space rather than through other routes could be wrong
International Endodontic Journal, 44, 183–194, 2011
• Route of leakage between the two chambers: inadequately controlled for
• Check the interface between outer root surface and the sealing material used to separate the chambers
International Endodontic Journal, 44, 183–194, 2011
Voids • Concern when using GP• Eguchi et al.• ‘using different condensation techniques and different sealers
would likely produce more sealer (and less GP) in some areas of the canal
• Obturating techniques: the most mass of core filling material would require much less sealer for an adequate canal seal
Tissue toxicity
(1) cytotoxicity evaluation(2) subcutaneous implantation(3) intraosseous implantation(4) in vivo periapical Chisholm: ZnO & oil of cloves 130 years ago, to dentistry• Eugenol: quite cytotoxic• Proven track record
Obturation Errors• Result of inadequate cleaning and shaping • If not an instrumentation error: reversible procedural error on
the obturation check film• Gross overextension of material into the periapical tissues:
conventional means /periapical surgery• Difficulty with the obturation phase: Cleaning and shaping
technique should be reevaluated prior to consideration of changing obturation techniques
Colleagues for Excellence. Fall 2009
Summary • The most desirable way to render RCs innocuous is to clean
and shape them, to eliminate bacteria and tissue debris from within them, & then to obliterate them by means of a dense 3D filling
• Root canal filling procedures should be directed toward the filling of significant lateral canals as well as the filling of main root canals
• The final test of a root canal filling is its capacity to seal off the RC system from the periapical tissues
References
• Cohen’s Pathways of the Pulp• Endodontics. 6th ed. • R. M. E. Tomson, N. Polycarpou & P. L. Tomson. Contemporary
obturation of the root canal system .BRITISH DENTAL JOURNAL VOLUME 216 NO. 6 MAR 21 2014
• Schilder H, D.D.S. Filling Root Canals in Three Dimensions. JOE — Volume 32, Number 4, April 2006, 281-290
• Obturation of Root Canal Systems . Colleagues for Excellence. Fall 2009
• D . Ricucci. Apical limit of root canal instrumentation and obturation, part 1. Literature review. International Endodontic Journal (1998) 31, 384-393
• D. Ricucci & K. Langeland. Apical limit of root canal instrumentation and obturation, part 2. A histological study. International Endodontic Journal (1998) 31, 394-409
• Schaeffer MA, White RR, Walton RE. Determining the Optimal Obturation Length: A Meta-Analysis of Literature. JOE — Volume 31, Number 4, April 2005
• De-Deus G. Research that matters - root canal filling and leakage studies. Int Endod J. 2012 Dec;45(12):1063-4.
• James L. Gutmann. Root Canal Obturation: An update. www.ineedce. com.
• D.-K. Rechenberg, G. De-Deus & M. Zehnder. Potential systematic error in laboratory experiments on microbial leakage through filled root canals: review of published articles. International Endodontic Journal, 44, 183–194, 2011