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Procedure
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Often involves one or two long appointments, where full mouth opening will be necessary.•
Local anaesthesia will usually be required initially.•
A rubber dam may be used, which may be a new experience.•
Antibiotics may be required to control any infection.•
Temporary dressings may be used, and care will be required not to dislodge them.•
Postoperatively, anti-inflammatories may be recommended.•
Patient may experience some tenderness postoperatively and may need to contact the surgery if this worsens.459
At the second visit:
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the temporary filling and dressing are removed•
if the root canal is still clean and dry, it is obturated with gutta percha (GP) to seal off the entire canal to within a millimetre of the apex.Instrument details
Barbed broaches are single-use disposable hand instruments for removing the pulp. They consist of a fine wire with multiple barbs. When the broach is inserted in a root canal and rotated, its barbs snag into the pulp tissue and pull it out of the canal as the broach is removed.
Root reamers resemble wood drills and are used for enlarging root canals in a circular fashion so that a filling can be inserted. They are made in standardised sets – all of the same length but with an increasing range of widths. Each reamer is numbered or colour-coded to indicate its size. The reamer is inserted in the canal and advanced by hand or by specially adapted handpieces for use Table 15.9 Specific instruments for root canal therapy
Item Function
Broach Plain broach to help locate the entrance to each root canal Barbed broach (Figure 15.35a) to remove (extirpate) the pulpal contents from the canal
Reamer
(Figure 15.35b) Hand or rotary – to enlarge the root canals in a circular shape laterally, down to the root apex
File
(Figure 15.35c) Hand or rotary – to enlarge the canal in its actual shape laterally, smooth the root canal walls, and remove any residual debris from them
Irrigation syringe
(Figure 15.36) Blunt ended with a side bevel, to irrigate and wash out debris from the root canal without injecting the syringe contents through the root apex
Solutions used include chlorhexidIne, sodium hypochlorite, local anaesthetic solution
Metal ruler Used with a file in place, to work out the full length of each root canal by comparing a periapical radiograph view of the tooth to the established working length
Apex locater
(Figure 15.37) To determine the working length electronically Spiral paste
filler (Figure 15.35d) Used with the slow dental handpiece to spin sealant material into the root canal
Lateral condenser or finger
spreader (Figure 15.38) Used to condense the root filling points laterally into each root canal, so that no space remains for micro-organisms to return Not required if root filling material used is inserted while hot and flowable
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with rotary endodontic instruments. As very few root canals are exactly circular in shape, reamers have largely been superseded by files.
Root canal files are hand or handpiece instruments which are similar to reamers but are flexible, and can be engaged around the walls of any canal shape present in the tooth. They are also made in the same standardised range of sizes and colours as reamers. Their function is to smooth and clean the walls of enlarged root canals and remove debris, and their flexibility allows them to nego- tiate curved root canals as well as the more typical oval shape of root canals (rather than circular).
They are inserted in the canal and used with a down-twist-and-up filing action against the canal walls. Many practitioners use files exclusively instead of reamers, but in the same sequence of sizes.
Figure 15.36 Monoject syringe needle end.
(a)
(b) (c) (d)
Figure 15.35 Root canal instruments. (a) Barbed broach. (b) Root canal reamer. (c) Root canal file.
(d) Rotary paste-filler.
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Reaming and filing root canals by hand is laborious and time-consuming. However, the introduction of flexible nickel-titanium root canal instruments used with modern variable speed handpieces allows dentists to undertake these procedures far more easily and precisely. They are particularly useful for the curved canals of multirooted teeth.
In addition, some of these specialised handpieces are also electronic apex locators, and can be set to give an audible alarm when the tooth apex has been reached – this is called the working length.
Once determined, all other files used can then be premeasured to this length so that the root canal is fully obturated. When used correctly, the apex locator is far more reliable at determining the accurate working length of the tooth, and this can be confirmed with a postoperative periapical radiograph.
Root canal pluggers or spreaders have a long, tapered smooth point used to condense the gutta percha filling points against the canal walls and obliterate any gaps. These may also be referred to as lateral condensers, but they all have the same function.
Rotary paste fillers are engine instruments for inserting pastes into a root canal. They consist of a spiral wire which fits in a slow-running hand-piece and propels the required material to the full length of the root canal.
Figure 15.38 Finger spreader.
Figure 15.37 Endodontic apex locator handpiece.
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As with the use of some specific instruments for endodontic treatment only, there are materials and medicaments used exclusively in non-surgical endodontic treatment too, all of which will have been risk assessed in accordance with COSHH regulations Their potential to cause both the patient and dental personnel harm if misused must be fully appreciated and understood by the whole dental team. Consequently, working safely as a member of the dental team throughout chairside procedures should be second nature to the dental nurse, ensuring that there is no potential for accidents nor mistakes during any treatment session.
The materials and medicaments used in root canal therapy treatments are as follows.
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Irrigation solution – used during root canal preparation to lubricate the instruments and wash out any debris. The solution used is an individual choice between sodium hypochlorite (bleach), chlorhexidine (although some patients may be allergic to this), and local anaesthetic solution.•
Antiseptic paste – non-setting and containing antiseptic anti-inflammatories, and used to dress infected root canals for a time before root filling – an example is Ledermix paste (Figure 15.39).•
Cresophene – medical-grade creosote used to dress infected root canals for a time, soaked onto paper points before insertion (Figure 15.40).•
Lubricating gel – for use with engine files and reamers (those used with a handpiece) to ensure the instruments do not snag on the canal walls and snap during use – an example is Glyde (Figure 15.41).Figure 15.39 Ledermix paste.
Figure 15.40 Cresophene antiseptic.
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Gutta percha (GP) points – varying diameter tapered rubber points used to fill (obturate) the root canal system, with the same colour-coded width system as files and reamers (Figure 15.42), so if a ‘red’ (size 25) file or reamer is used as the final canal preparation instrument, then a red GP point must be used to obturate the root canal.•
Sealing cement – setting cement used to aid the insertion of the GP points and to seal off any residual spaces in the root canal; some contain antiseptics and anti-inflammatories.•
Restorative materials – used to restore the tooth to full function and appearance after root filling, as discussed earlier.Pulpectomy preparation
As the root canal must be disinfected before it is filled, all instruments and dressings used must be sterile. A convenient arrangement is to keep a sealed container holding a complete sterilised root canal therapy kit ready for immediate use (Figure 15.43).
Figure 15.41 Glyde endodontic lubricant.
Figure 15.42 Gutta percha points.
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Wherever possible, a rubber dam should also be applied to the tooth under treatment before access to the root canal is made, as it is the best method of:
•
preventing ingress of micro-organisms from the mouth into the root canal•
preventing accidents such as inhalation or swallowing of small root canal instruments•
improving access and visibility for the dentist.The items required for the application and use of rubber dam are illustrated in Figure 15.44.
A non-latex purple or blue rubber dam should be available for use on patients who are, or may be, sensitive to latex, otherwise the regular green latex dam sheets are used. If, for whatever reason, use of a rubber dam is impractical, small root canal hand instruments must have a length of dental floss or a parachute chain attached, to allow them to be retrieved if they accidentally slip out of the dentist’s hand. Engine reamers and files will be locked into the handpiece by their latch grip device, in the same way as dental burs are for restorative treatment.
Procedure
Modern infection control practice stipulates that all endodontic instruments inserted into a root canal must be considered as single use and safely disposed of in the sharps box. A new set of instruments must then be used on the next patient, and disposed of in a similar fashion.
Figure 15.44 Rubber dam instruments.
Figure 15.43 Endodontic tray.
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As mentioned earlier, more than one visit may be necessary. The following description is for a two-visit procedure carried out under ideal conditions.
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Local anaesthetic is used if the pulp is still vital.•
A rubber dam is applied, then the area of the tooth is swabbed with a disinfectant such as chlorhexidine.•
Access to the pulp chamber is gained by drilling through the tooth with conventional diamond burs.•
Access to each root canal is gained by drilling at the base of the pulp chamber, using a stainless steel bur or a Gates Glidden drill (Figure 15.45).•
Any intact pulp tissue can be extirpated with a barbed broach.•
The length of the root canal must be measured before any further instrumentation is undertaken – this is called the working length. This is done by taking a diagnostic periapical radiograph with a root reamer or file of known length inserted in the canal, and using a paralleling technique, or by the use of an electronic apex locator.•
Once the radiograph shows the required length of canal preparation (1 mm short of the apex), all subsequent reaming and filing are kept to this length by fitting a stopper to each instrument before insertion. This prevents penetration of the apical foramen or too short a preparation of the canal.•
The walls of the root canal are smoothed and cleaned with files to produce a smooth-bordered canal which tapers from a wide entrance to a narrow apical end. It is achieved by using a wide file at the root canal entrance followed by successively narrower files until the preparation reaches its end point, 1 mm short of the apical foramen. This results in a wide entrance to the root canal, with adequate visibility and access for instrumentation, and a progressively narrower taper towards the apex.•
Throughout reaming and filing, the canal is irrigated with a disinfectant such as sodium hypochlorite or chlorhexidine to remove debris and disinfect the canal. A special sterile disposable syringe, with a blunt end and a side bevel (Monoject syringe), is used for this purpose. The side bevel prevents the irrigation solution from being injected through the apex into the surrounding tissues – this is especially undesirable when sodium hypochlorite is used.•
The canal is then dried with absorbent paper points (Figure 15.46) and its entrance covered with dry sterile cotton wool, or if infection was present before cleaning, an antiseptic-soaked paper point can be left in the canal.•
The pulp chamber is sealed off with a temporary filling to prevent contamination of the empty, clean, dry root canal between visits – suitable materials are Cavit or Kalzinol.Figure 15.45 Gates Glidden drill.
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At the next visit, if the root canal is still clean and dry, or all signs of infection have gone, it is ready for insertion of the permanent filling. A gutta percha point of the same colour code as the last file or reamer used is selected. This is called the master point and has to be sealed to the apical end of the canal with cement.•
Various proprietary brands of root canal sealers are available, many being based on a modified zinc oxide-eugenol cement, such as Tubliseal. The canal walls and the end of the master point are coated with sealer and the point inserted into the root canal.•
The gap between the canal walls and the master point is filled by condensing successive GP points against the canal walls with a finger plugger or lateral condenser until no space is left.•
Warming the spreader softens the GP points and assists condensation against the canal walls.The use of self-locking tweezers facilitates handling of paper and GP points.
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Alternatively, flowable GP can be used before inserting the master point, so that the liquid material is pushed into any lateral canals as the point is inserted.•
Another alternative technique uses preheated GP and pluggers to provide easier and effective sealing by vertical condensation – examples are Thermafil (Figure 15.47) and Alphaseal.Figure 15.46 Paper points.
Figure 15.47 Thermafil system.
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Whichever method is used, it must ensure that each end of the root canal has a leak-proof seal once obturation is completed.•
A periapical radiograph is taken to ensure that the root filling is satisfactory and to check the subsequent progress of the tooth (Figure 15.48).•
Having completely filled the root canal with GP, the access cavity and pulp chamber are lined with glass ionomer cement and filled with composite or amalgam.If, at step 10, the root canal is not dry, it means that apical infection is still present. In that case the canal is debrided again and irrigated with disinfectant, dried with paper points and another tem- porary dressing is inserted in the access cavity. It should then be ready for a permanent root filling at the next visit. If not, a temporary root dressing of non-setting calcium hydroxide paste is inserted until the next visit. The paste is available as materials such as Hypocal, or it can be made by mixing calcium hydroxide powder with sterile water or local anaesthetic solution. The paste is inserted into the canal with a rotary paste filler.