Endodontics Flashcards
How will lack of planning affect endodontic treatment?
Difficulties during treatment or failure of the procedure.
What are the indications for endodontic treatment?
- Irreversible pulpitis
- Periapical pathology
- Post retained restoration
- Overdenture
- Teeth with doubtful prognosis
- Periodontal disease
- Pulp sclerosis following trauma
What are the features of irreversible pulpitis?
The patient history shows:
- Lingering pain
- Spontaneous
- Kept awake
The clinical exam shows:
- Exaggerated response to sensibility testing
- May be difficult to locate the tooth responsible
Placing a sedative dressing may relieve the symptoms but the diagnosis stays. Endodontic treatment should be scheduled.
What can the diagnoses be for periapical pathology?
- Acute/chronic periapical periodontitis
- Acute/chronic apical abscess
Early presentations of chronic disease may be difficult to diagnose.
What planning is required for a post-retained restoration?
This is where a tooth has lost too much tooth structure to retain an indirect restoration without the use of an endodontic post. There needs to be careful assessment of the remaining tooth structure. Ask: can a direct composite core be used?
What is the exception to root treating roots for an overdenture?
Teeth may be decoronated to provide support as an overdenture abutment. These teeth should undergo endodontic treatment and the only exception is if the canal is highly sclerosed with no periapical pathology.
Why are teeth with doubtful pulps sometimes root treated?
Consideration should be given to root treating teeth with a doubtful prognosis especially if the tooth is to be crowned or be a bridge abutment. If endodontic treatment is undertaken at this age it will be easier to undertake and have a better prognosis. Research has shwon that a significant number of vital teeth will become non-vital following crown/bridge preparation.
When are teeth root treated in periodontal disease?
This may be done for perio-endo lesions. In multi-rooted teeth one root may have significant pathology and this is an indication for root resection. If root resection is planned then endodontic treatment should be undertaken prior to resection.
When is root treatment used to treat pulp sclerosis following trauma?
Teeth which retain vitality after trauma may respond by laying down secondary dentine resulting in gradual narrowing of the pulp space. This is not an indication for root treatment in isolation. However it will be easier if undertaken prior to complete pulp sclerosis. The patient may also be concerned regarding yellow discolouration which can only be reliably treated with elective endodontics and internal bleaching.
What are the contraindications to root canal treatment?
General: - Inadequate access - Poor-oral hygiene/status/attitude - General medical condition Local: - Tooth not restorable - Insufficient periodontal support - Non-strategic tooth - Root fractures - Root resorption - Bizarre anatomy
Why might a patient have inadequate access and how can this be managed?
Patients with limited mouth opening may not be suitable for endodontic treatment. The reasons for limited access are:
- Microstomia
- TMD
- Previous radiotherapy
- Overeruption of lower anterior teeth
- Scleroderma
A general rule is that it should be possible to place 2 fingers between the patients incisors. Consider using mouth props if the patient finds wide mouth opening challenging.
Why does poor oral hygiene/status/attitude affect whether endodontic treatment can be done?
Endodontic treatment should not be carried out if a patient is not able to maintain a healthy oral status. Medically compromised patients may be an exception to this. Think about the long term outcome. Patients with poor motivation towards dental treatment are unlikely to complete the treatment.
How can medical conditions affect endodontic treatment?
There are no specific medical contraindications to endodontic treatment. However the patient has to be well enough to undergo a relatively long dental procedure possibly for multiple appointments. If the patient is older this will be compounded by the endodontic treatment itself being more complex due to canal sclerosis.
Why is root canal treatment not done on an unrestorable tooth?
It must be possible following root canal treatment to restore the tooth to health and function. The finishing line of the restoration must be supracrestal and preferably subgingival. Don’t start endodontics on a tooth with questionable restorability as you are not doing yourself or the patient any favours.
Why is insufficient periodontal support a contraindication for root treatment?
The tooth should have periodontal support to ensure the medium to long term survival of the tooth. Endodontics is difficult enough without having to work on a moving tooth. Teeth with significant periapical infection/acute abscess may be mobile due to the pathology but this will hopefully heal following the endodontic treatment.
Why might you not carry out root canal treatment on a non-strategic tooth?
If a tooth is unopposed and non-functional the benefit of endodontic treatment versus extraction should be considered. A reason to save an unopposed tooth may be to maintain a distal abutment for a partial denture.
What is the treatment for a root fracture and what are the signs?
Sub-crestal/vertical root fractures have a very poor prognosis and extraction is the only option. Clinical signs include an isolated, narrow, deep periodontal pocket. Radiographic signs include a J shaped radiolucency around the tooth or obvious displacement of the root fragments.
What are the types of root resorption that can affect endodontic treatment?
- External root resorption
- External cervical resorption
- External replacement resorption
- Internal root resorption
What is external cervical root resorption?
It has unknown aetiology and may be associated with previous trauma. Resorption usually starts subgingivally in the cervical region. The pulp is usually vital and only becomes involved when the lesion has progressed extensively. It is often asymptomatic.
How is external cervical root resorption diagnosed and treated?
Diagnosis is based on clinical and radiographic findings. CBCT may be useful to assess the extent of the lesion. Treatment involves surgical exploration of the lesion followed by repair. Endodontic treatment may or may not be required. This is specialist treatment and referral should be instigated as soon as diagnosis is suspected.
What is external replacement resorption?
The root surface is gradually replaced with bone and this is also known as ankylosis. It often has a traumatic origin. It can be transient and self-limiting but will often progress until complete root replacement occurs. The rate of replacement is often faster in children.
How is external replacement resorption diagnosed and treated?
Diagnosis is based on radiological appearance and clinical examination which will show a high pitched, metallic sound on percussion. The tooth will be non-mobile and may become infra-occluded in children who are still growing. There is no treatment which can stop the ankylosing process.
What is internal root resorption?
It occurs entirely within the canal system and results in an ovoid expansion of the root canal. The outline of the canal will be lost around the area of resorption. The pulp will likely be chronically inflamed. A ‘pink spot lesion’ may be visible through the enamel. The tooth is usually partially vital and there may be symptoms of pulpitis.
What is the treatment for internal root resorption
Endodontic treatment is required. Obturation can be difficult due to the unusual canal anatomy. Thermal obturation techniques (involving backfill with molten GP) is required.
What bizarre anatomy could make endodontics difficult?
Features may include:
- Exceptionally curved roots
- Dilacerated teeth
A pre-treatment assessment should identify any unusual features that will increase the complexity of the endodontic treatment. Referral to a specialist would be recommended for a further opinion and treatment is possible.
How does radiotherapy affect bone tissue?
It is often used for the treatment of cancers, either as the sole treatment modality or as an adjunct to surgery/chemotherapy. The mandible and/or maxilla is often involved in the radiotherapy beam in head and neck cancer. The effect on bone tissue is to reduce its vascularity (end arteritis obliterans).
What are osteoclast inhibitors?
Bisphosphonates are a class of drug which are used to inhibit bone resorption. They are used to treat diseases which present with increased bone resorption such as osteoporosis, Paget’s disease and bone cancers/metastases. Examples include alendronate (Fosamax) and zolendronic acid. They can be delivered orally or IV depending on the dose and aetiology. New drugs such as denosumab have a similar effect but are not part of the bisphosphonate group.
What affect do osteoclast inhibitors and radiotherapy on root treatment?
Patients who have undergone radiotherapy in the head or neck region or who have taken osteoclast inhibitors are at increased risk of osteonecrosis of the jaw. This is a serious and painful condition which is difficult to treat and can result in significant disfigurement. The causes of osteonecrosis include dental extractions. For this reason, people who are risk of osteonecrosis should be strongly considered for endodontic treatment rather than extraction. This may mean trying to endodontically treat a tooth which would otherwise be considered unrestorable. In this case the tooth can be de-coronated and left as a root face with an appropriate restoration covering the root.
What are the arguments for implants versus endodontic treatment?
Endodontics has an 80-90% success rate whereas with implants it can be 95%. However the success rate of implants is actually more correctly a ‘survival’ rate ie the implant is still in situ. Success depends on certain factors for example is the implant still functional and has it suffered complications or pathology. When strict success criteria are applied to implants the success rate declines dramatically. Implants are still a very successful treatment option but patients should be aware of all associated complications and limitations. Implants should not be considered an alternative for endodontics. They are an option for certain patients to replace a missing tooth once a tooth has failed and is deemed unrestorable.
When should endodontics be referred?
The GDC state that you should only perform treatment which you feel adequately trained and confident to perform.
You can refer to a dental hospital/department with an endodontic service nearby but many will have acceptance criteria. The alternative is to refer to a local endodontist but they will charge.
What are the tricalcium silicates in dentistry?
- MTA
- Biodentine
What is portland cement?
It is a hydralic cement that not only hardens by reacting with water but also forms a water-resistant product. Portland cement clinkers are comprised of:
- Tricalcium silicate (CaO)3.SiO2 45-75%
- Dicalcium silicate (CaO)2.SiO2 7-32%
- Tricalcium aluminate (CaO)3.Al2O3 0-13%
- Tetracalcium aluminoferrite (CaO)4.Al2O3.Fe2O3 0-18%
- Gypsum CaSo4.2H2O 2-10%
- Clinkers are pulverized to form a powder
What is the composition of portland cement?
Powdered clinkers make up over 90% of he final powder. Calcium sulphate is added which controls setting over time. There are up to 5% other contituents (fillers).
What are the typical constituents of Portland cement?
- Calcium oxide CaO 61-67%
- Silicone dioxide SiO2 19-23%
- Aluminium oxide Al2O3 2.5-6%
- Ferric oxide Fe2O3 0-6%
- Sulphate 1.5-4.5%
What is the composition of MTA?
It is the same as portland cement but without traces of arsenic and lead. There is the additional of bismuth oxide 20% for radiopacity. It has smaller and more uniform particle size. It contains less gypsum which is an inhibitor to control working time. It is medical grade Portland cement. Approval was given for its use in dentistry in 1998. It is expensive and there is grey and white.
What are the properties of MTA?
- Biocompatible
- Non-toxic
- Non-resorbable
- No leakage around margins
- Very alkaline when mixed with water
- Compressive strength equal to IRM - cannot be used for direct restorative material
- Bactericidal
- Histological analysis showed that cementum can form over the surface of MTA - biocompatible
What are the uses of MTA?
- Root end restorations following apical surgery
- Repair of lateral/furcation root perforations
- Pulp capping (primary and secondary dentition)
- Apexification in immature roots
- Repair of resorption defects
How do you use MTA?
- Mix powder with sterile water in a 3:1 ratio on a glass slab
- Add small amounts of water to keep the handling properties correct
- Deliver MTA using appropriate instrument
- If using internally place a cotton wool pellet in contact with the MTA to allow it to set
- If using external to the tooth e.g. RRF moisture will be taken from the surrounding tissues
What happens with MTA after placement?
Upon hydration MTA forms a colloidal gel that solidifies to a hard structure in 3-4 hours. The initial ph of 10.2 rises to 12.5 after 3 hours. The strength increases in the presence of moisture for up to 21 days.
How can MTA be used in perforation?
Clean and flush it out. Dry the area and place MTA using a plugger over the perforation. Pack with some GP or paper point (80 or 90).
How do MTA and dycal compare as a pulp capping material?
Research has shown favourable results for MTA. Results from a study show iatrogenic pulpal wounds treated with MTA were mostly free from inflammation after 1 week and became covered with a compact hard tissue barrier of steadily increasing length and thickness within 3 months following capping. Control teeth treated with dycal revealed less consistent formation of a hard tissue barrier that had numerous tunnel defects at 3 months and at 1 week there is still inflammation. So with MTA better hard tissue healing and reducing inflammation. MTA has a higher success rate, results in less pulpal inflammatory response and a more predictable hard dentine bridge formation.
What are the inadequacies of MTA?
- Takes several hours to set
- Can be washed away before its set
- Handling properties
- Acidic environment will interfere with the setting process - placement site needs to be infection free
- Cost
What does the liquid and powder in Biodentine?
Powder:
- Tricalcium silicate C3S (main core material)
- Di-calcium silicate C2S (second core material)
- Calcium carbonate and oxide (filler)
- Iron oxide (shade)
- Zirconium oxide (radio-opacifier)
Liquid:
- Calcium chloride (accelerator)
- Hydrosoluble polymer (water reducing agent)
What are the properties of Biodentine?
The setting period is 9-12 minutes (initial set). Compressive strength during setting remains high and is comparable to GIC. Biodentines compressive strength reaches the same level as human dentine after 28 days. Biodentine shows a similar flexural modulus as dentine, ensuring similar mechanical behaviour. Biodentine cuts like dentine giving a similar sensation under the bur. Its ivory shade and opacity allow easy differentiation from tooth structure. Biodentine enters dentinal tubules so there is micromechanical bonding. It won’t leak much as there is a really good seal with natural tooth structure. Biodentine is the first all in one biocompatible and bioactive crown-root dentine substitute to use wherever dentine is damaged. There is tooth vitality preservation thanks to reactionary dentine genesis and reduction of therapeutic failures thanks to its microleakage resistance. It has both endo and restorative indications thanks to physical properties similar to human dentine.
What are the uses of biodentine?
They are similar to MTA. However dentine can be used as a bulk restorative material for permanent dentinal restorations, temporary enamel restorations and endodontic repairs.
How is biodentine used?
It comes as a capsule. You add liquid to the capsule and place in an amalgamator. It can be used as a pulp cap and to rebuild the tooth. After 24 hours it can be prepared for a permanent restoration.
What is the aim of obturation?
The establishment of a fluid tight barrier with the aim of protecting the periradicular tissues from microorganisms which reside in the oral cavity. A hermetic seal is required from the coronal orifice of the canal to the apical foramen at the cemento-dentinal junction.
What three main functions are served by a well obturated system?
- Prevent coronal leakage of microorganisms or potential nutrients to support their growth into the dead space of the root canal system
- Prevent periapical or periodontal fluids percolating into the root canals and feeding microorganisms
- Entomb any residual microorganisms that have survived the debridement and disinfection stages of treatment in order to prevent their proliferation and pathogenicity
What are the ideal properties of a root filling material?
- Easy handling and ample working time
- Seal the canal laterally and apically conforming to the complex internal anatomy
- Dimensionally stable
- Non-irritant
- Does not stain tooth structure
- Anti-microbial
- Impervious and non-porous
- Unaffected by tissue fluid
- Radiopaque
- Easily removed
What is gutta percha?
It is a naturally occurring rubber. Traditional GP contains:
- Zinc oxide 65%
- Gutta percha 20%
- Radio opacifier (metal sulphate) 10%
- Plasticiser 5%
It is produced in a variety of cone sizes.
What are the phases of GP?
GP occurs in 2 crystalline forms which are the alpha and beta phases. Below 42 degrees it is in the beta phase and between 42-49 it is in the alpha phase. Above 49 GP becomes amorphous. Upon cooling it returns to the beta phase.
What is the role of an endodontic sealer?
- Seal the space between the obturating core material and the internal root surface
- Fill the space between core and accessory filling materials in lateral condensation
- Seal the irregularities of the complex anatomy (lateral canals, tubules etc)
- Lubricate and facilitate seating of the core and accessory filling material
What are the types of endodontic sealers?
- Zinc-oxide/eugenol-based (most popular with long track record e.g. tubliseal)
- Calcium hydroxide based (less antimicrobial but also less toxic than zinc oxide eugenol e.g. sealapex)
- Glass ionomer based (not commonly used, difficult to remove e.g. Ketac-endo)
- Resin based (superior sealing ability, adheres to dentine and antimicrobial e.g. AHPlus)
- Calcium silicate based (e.g. smartphase bio, MTA fillpex - limited research at this stage)
- Silicone based (e.g. Roekoseal - limited research at this stage)
What are the obturation techniques?
- Lateral compaction (cold and warm)
- Single cone
- Thermomechanical compaction
- Warm vertical compaction (continuous and interrupted wave)
- Carrier based
- Apical barrier
What is cold lateral compaction?
Choose an ISO master GP point that fits snugly with tug-back, coat with sealer and place to working length. Place a finger spreader down to 1mm from the working length. Place an accessory point where the finger spreader was removed, ensuring it extends to 1mm from the working length. Continue the process and the finger spreader will get further from the working length. After placing 2/3 accessory points consider taking a mid-fill radiograph. Continue until all the accessory points fill to just below the canal orifice. Once complete, sear the cones off at orifice level and compact vertically.
What is warm lateral compaction?
It is a modification of cold lateral compaction. It uses ‘energised spreading’. The technique:
- A k type file is inserted into the piezoelectric ultrasonic unit
- The file is activated and introduced into the GP generating heat to soften it
- A finger spreader is then placed followed by an accessory point as in the cold lateral technique
It may have an advantage over cold lateral as the thermoplasticised GP may flow into accessory anatomy.
What is single cone?
This is when only the master GP point with sealer is used to obturate. It is only applicable with greater taper GP points matched to the preparation file e.g. F1, 2, 3 GP points for protaper. It does not provide a good 3 dimensional seal and it not recommended. A newer material ‘smartseal’ uses a single cone which expands when coated in a hydrophilic polymer. It is a resin based system with a calcium silicate based cement ‘smartpastebio’. There is not enough evidence yet to assess its effectiveness.
What is thermomechanical compaction?
It uses heat generated from a reverse Hedstrom file which is driven with a slow handpiece into the GP. A master point is placed with sealer and the instrument placed 3-4mm from the working length. The GP is driven apically and laterally and the file driven coronally. It can cause extrusion from the apex and its possible for the instrument to fracture in the canal.
What is warm vertical compaction?
It is a modification of Schilder technique introduced in 1967 and can be divided into:
- Continuous wave compaction
- Interrupted wave compaction
What are the two stages of continuous wave compaction?
- Downpack - aims to create an apical ‘plug’ of GP which seals and fills the apical 3-4mm of the canal thereby providing apical control
- Backfilling - aims to fill the remainder of the canal by squirting molten GP through a GP ‘gun’
What are the steps of continuous wave compaction?
1 - choose a GP point which fits the apical preparation and displays tug back just before the apical constriction
2 - choose a plugger which extends to approx 4mm from the apex and binds. Adjust the rubber stop to this length
3 - turn on the heat source and plunge the plugger through the GP point
4 - continue to apply pressure towards the pre-determined binding point. This should be done in one movement and only take 1-2 seconds
5 - the plugger will slow its apical movement and stop just short of the predetermined binding point. Stop the heat source and maintain apical pressure for 10 seconds to prevent cooling shrinkage of the mass
6 - activate the heat source again and complete the pressure until the binding point is reached. Then wiggle the plugger tip and remove it from the canal
7 - as the plugger is removed any GP coronal to the tip is also removed leaving a plug of GP sealing the apical third
8 - place the tip of the injectable GP gun against the plug of apical GP and extrude GP in bursts of 3-4mm
8 - after each application of GP use a condenser to compact the GP which has just been placed, then continue placing further GP in this manner until the canal orifice is reached
10 - completed obturation
What are the advantages of continuous wave compaction?
- Has been shown to provide improved 3D obturation compared to cold lateral condensation
- The canal is filled with a homogenous mass of GP with no carrier
- Good for filling internal resorption defects and other anomalous anatomy
What are the disadvantages of continous wave compaction?
- Technique sensitive and takes time to master
- Requires relatively expensive material
What is interrupted wave compaction?
It is very similar to continuous wave technique. However, the downpack is carried out in multiple waves rather than one continuous wave. It is recommended for wider canals.
What is carrier based obturation?
It consists in a carrier coated in GP. Thermafil is the market leader. It utilises a plastic carrier surrounded by heated GP which is inserted into the canal. The carrier is then cut at the entrance of the canal leaving the remaining carrier and GP in the canal.
What is the technique for carrier based obturation?
- Choose a thermafil carrier which matches the size of canal preparation undertaken
- Use a verifier or a carrier with the GP stripped off to check it can be inserted to the full working length
- Take a radiograph if required
- Modify the thermafil point to achieve better length control and reduce the amount of excess GP
- Place the rubber stopped at the correct length
- Dry the canal
- Apply sealer (extra working time) to the entrance of the canal using a probe
- Place thermafil point into the oven
- Press the correct button according to the size and then press start
- The oven will beep when the GP is heated correctly
- Remove the thermafil point from the oven
- Insert the point into the canal up to the rubber stopper
- Use a plugger to condense the GP in the coronal portion of the canal
- Use a thermacut bur to remove the carrier and any excess GP at the entrance to the canal
