2 Purpose of root canal filling To prevent bacteria and bacterial elements from spreading from (or through) the canal system to the periapical area,the fully instrumented root canal has to be provided with a tight and long-lasting obturation.A root canal filling material should, therefore, prevent infection/reinfection of treated root canals. Together with an acceptable level of biocompatibility (inert material) this will provide the basis for promoting healing of the periodontal tissues and for maintaining healthy periapical conditions.
4 Instruments for root canal filling Lentulo spiral ﬁller/rotary paste ﬁllerFunction and features• Small ﬂexible instrument used to place materials into the canal• Fits into the conventional handpiece• Use with caution as it can be easily broken• Different sizes available
5 Finger spreaderFunction, features and precaution• Used to condense gutta percha into the canal during obturation• Finger instrument with a smooth, pointed, tapered working end• Disposed of in the sharps’ containerVarietiesCan be of the hand instrument type (lateral condenser)
6 Endodontic pluggerFunctionWorking end is ﬂat to facilitate plugging or condensing the gutta percha after the excesshas been removed by melting off with a heated instrumentVarieties• Different sizes of working ends are available•Available as hand or ﬁnger instruments
7 Gutta percha pointsFunction and features•Non-soluble, non-irritant points that are condensed into the pulp chamber during obturation• Standardised type: follows same ISO classiﬁcation as endodontic ﬁles• Non-standardised: have a greater taper than the standard ISO typeVarieties• Can be packaged in single dose or bulk packages• Different sizes with different tapers available
8 OBTURATING MATERIALS Core Obturation Materials Historically, a variety of materials have been employed to obturate the root canal, falling into three broad categories:solidssemisolidspastes(sealers)
9 SealersSealers fill the space between the canal wall and core obturation material and may fill lateral and accessory canals, isthmuses, and irregularities in the root canal system.
10 Obturating materials Ideal properties of root canal filling materials: AntimicrobialBiocompatible.Good flowAdhesive in natureDimensionally stableNot affected by moistureRadio-opaqueGood handlingEasily removed, post prep or retreatDoes not stain dentineCheap10
11 The most popular sealers are grouped by type: Zinc oxide-eugenol formulationsCalcium hydroxide sealersGlass- ionomersResinsRegardless of the sealer selected, all are toxic until they set. For this reason, extrusion of sealers into the periradicular tissues should be avoided.
12 Sealers based on calcium hydroxide An easy, effective method of sealer application. The file covered with sealer will be inserted and spun counterclockwise to coat thecanal walls.
13 Indications for the use of calcium hydroxide include: As a temporary dressing for canals where filling has to be delayed.In the treatment of resorption.In the management of perforations.To promote apical closure in immature teeth.
14 Indications of calcium hydroxide sealer Apexification - treatment procedure by which closure of root apex is promoted by calcium hydroxide, in teeth where loss of vitality has occurred before normal growth and development of the tooth was completed.Apexogenesis - treatment procedure by which the preservation of the radicular pulp tissue allows continuing development and apical maturation of teeth with open apices.
15 Acceptable methods of placing the sealer in the canal include the following: Placing the sealer on the master cone and pumping the cone up and down in the canalPlacing the sealer on a file and spinning it counter clockwisePlacing the sealer with a lentulo spiralUsing a syringeActivating an ultrasonic instrumentThe clinician should use care when placing sealer in a canal with an open apex to avoid extrusion.
16 Solid materialsSilver cones met many of the criteria for filling materials but suffered from several deficiencies.When leakage occurred and the points contacted tissue fluids, they corroded, further increasing leakage.
17 Semisolid materialGutta-percha, a semisolid material, is the most widely used and accepted obturating material.Typical composition of gutta-perchacones.
18 ResinResin-based obturation system contains primer, sealer, and cones. The cones resemble gutta-percha and can be placed usinglateral or warm vertical compaction. Pellets are available for thermoplastic injection.
20 Root canal filling technique. Solid core technique Single coneThe single-cone technique consists of matching a cone to the prepared canal. For this technique a type of canal preparation is advocated so that the size of the cone and the shape of the preparation are closely matched.
21 Cold lateral condensation This is a commonly taught method of obturation and is the gold standard by which others are judged.The technique involves placementof a master point chosen to fitthe apical section of the canal.Obturation of the remainder isachieved by condensation ofsmaller accessory points. Thesteps involved are:
22 1. Select a GP master point to correspond with the master apical file instrument. This should fit the apical region snugly at the working length so that on removal a degree of resistance or 'tug-back' is felt. If there is no tug-back select a larger point or cut 1 mm at a time off the tip of the point until a good fit is obtained. The point should be notched at the correct working length to guide its placement to the apical constriction.2 . Take a radiograph to confirm that the point is in correct position if you are in any doubt.3. Coat walls of canal with sealer using a small file.4. Insert the master point, covered in cement.5 . Condense the GP laterally with a finger spreader to provide space into which accessory points can be inserted until the canal is full.6. Excess GP is cut off with a hot instrument and the remainder packed vertically into the canal with a cold plugger.
23 Sketch showing a cross-sectional cut through a root canal filled with a master cone and multiple accessory cones
24 Warm lateral condensation As above, but uses a warm spreader after the initial cold lateral condensation. Finger spreaders can be heated in a flame or a special electronically heated device (Touch of heat) can be used.
25 Diagram of the warm vertical condensation technique. A, After a heated spreaderis used to remove the coronalsegment of the master cone,a cold plugger is used to applyvertical pressure to the softenedmaster cone.B, Obturation of the coronalportion of the canal isaccomplished by adding a gutta-percha segment.C, A heated spreader is used tosoften the material.D, A cold plugger is then usedto apply pressure to thesoftened gutta-percha.
26 Thermoplasticized injectable GP (e.g. Obtura, Ultrafil) Thermomechanical compactio
27 Coated carriers (e.g. Thermafil) These are cores of metal or plastic coated with GP. They are heated in an oven and then simply pushed into the root canal to the correct length. The core is then severed with a bur. A dense filling results, but again apical control is poor and extrusions common. They are expensive and difficult to remove.
28 GuttaFlow is a cold flowable injection system that combines a silicone-based matrix with finely ground gutta-percha. It is used inconjunction with a master gutta-percha point without the need for compaction.
29 Glass ionomer–coated gutta-percha points (A) are used in conjunction with a glass ionomer sealer (B) to attempt to create a monoblock within the canal system.
30 A cast post and core provides the best foundation for restoring maxillary premolars. A, Resin composite core buildup, with a ferrule incorporated into the preparation.B, Full crown as the definitive restoration.
31 THE CORONAL SEALRegardless of the technique used to obturate the canals,coronal microleakage can occur through seemingly well-obturated canals within a short time, potentially causinginfection of the periapical area. A method to protectthe canals in case of failure of the coronal restoration is to cover the floor of the pulp chamber with a lining of glass ionomer cement after the excess gutta-percha and sealer have been cleaned from the canal.