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Endodontics: basic

ISSN 2398-2950

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Introduction

  • The endodontic system is the pulp tissue (vessels, nerves, and connective tissue) that are in the root canals and pulp chambers.
  • Endodontic disease refers to inflammation (pulpitis) or necrosis (partial or complete) of the pulp tissues.
  • The goal of endodontic therapy is to maintain a vital pulp system. Failing in maintaining pulp vitality, the goal is to remove the infection from while leaving the tooth in place. Thus, endodontic therapy is comprised of two main branches: vital and non-vital pulp therapy (root canal, surgical root canal, and apexification).
  • Vital pulp therapy consists of procedures to keep vital teeth alive, which are direct and indirect pulp capping.
  • Non-vital pulp therapy results in non-vital tooth, but can be performed on a living tooth to remove pain and infection. The three main procedures are: standard root canal Endodontics: root canal therapy, surgical root canal, and apexification.
  • These therapies present a viable alternative to extraction.
    These are advanced procedures and should not be attempted without significant study and practice.
Print off the owner factsheet Dental surgery - what to expect to give to your client.

Uses

  • Vital pulp therapy:
    • Fresh fractures in immature (incomplete apex) tooth Dental fracture.
    • Crown amputation for traumatic occlusions (orthodontic or post-operative mandibulectomy).
    • NOT recommended for mature teeth (standard RCT is preferred).
  • Standard root canal therapy Endodontics: root canal therapy:
  • Surgical root canal therapy:
    • Failed standard root canal therapy.
    • Root fractures Dental trauma: root fracture.
    • Inaccessible canals (stenotic root canals, instrument fracture).

Advantages

  • Vital pulp therapy and standard root canal therapy:
    • Resolves the problem (infection, pain, trauma) while maintaining the function of the tooth.
    • Much less painful than extraction (especially with strategic teeth).
    • Less immediate complications.
  • Surgical RCT:
    • Maintains the function of a tooth.

Disadvantages

  • Very technically demanding and if not performed perfectly will fail.
  • Time intensive.
  • Expensive set-up.
  • Long-term follow-up is required.
  • High failure rate if incorrectly performed.
  • Lack of clinical signs with failure.

Technical problems

  • Vital pulp therapy:
    • Continued hemorrhage.
    • Inability to place restoration.
    • Difficulty filling canal.
  • Standard root canal therapy:
    • Truly too many to mention.
    • Inability to find root canal.
    • Furcational perforation.
    • Improper working length.
    • Zipping, ledgeing, gouging.
    • Apical perforation.
    • Inadequate filling.
    • Instrument separation.
    • Over-under extension.
    • Inadequate obturation.
  • Surgical root canal therapy:
    • Unable to locate apex.
    • Iatrogenic oronasal fistula (maxillary canine, maxillary fourth premolar) Oronasal fistula.
    • Hemorrhage.
    • Inadequate/improper apecioectomy.
    • Inadequate/improper retrograde preparation.
    • Inadequate/improper retrograde fill.
    • Insufficient resultant root:crown ratio.

Alternative techniques

Time required

Preparation

Procedure

  • Vital pulp therapy: 30 mins.
  • Standard root canal therapy: 45-90 mins.
  • Surgical root canal therapy: 1-2 hours.

Decision taking

Criteria for choosing test

  • Vital pulp therapy: 
    • For crown amputation and immature canals ONLY.
  • Standard root canal therapy:
    • Any non-vital or endodontically involved tooth.
    • Complicated crown fracture.
    • Luxated/avulsed tooth.
    • Intrinsic staining.
    • Class II perio-endo disease (on periodontally healthy root).
  • Surgical root canal therapy:
    • Failed standard root canal, but only if you feel that you cannot perform a better conventional RCT.  
    • Procedural blockage from a pulp stone, file separation, or stenotic canal.
    • Incomplete apex in a young patient (prefer to attempt apexogenesis or apexification first).
  • Apical perforation or apical disease/resorption.
    • However only if severe, as these can often do very well with standard root canal therapy.

Risk assessment

  • Only standard anesthesia concern.
  • If long anesthesia is a concern, consider extraction.

Requirements

Personnel

Veterinarian expertise

  • The veterinarian must first be skilled in dental anatomy, radiology, pain management, and restorative techniques.
  • The veterinarian must be well trained prior to attempting any of these therapies in a living patient. Just reading a book/website is not sufficient - nor is attending a weekend wetlab.
  • Root canal therapy is exacting and perfection is necessary for a successful outcome. Plan on spending months practicing on extracted teeth or cadavers prior to performing this is a live patient.
  • Also, if the practitioner cannot expect to be doing a minimum of 5 root canal procedures/week, they will not develop the necessary skills to become qualified in this area.
  • Surgical root canals are even more difficult, requiring intricate knowledge of anatomy and a whole new set of equipment.
  • Vital pulp therapy, on the other hand, is much less technical, but just as exacting, and may be learned in a weekend laboratory. However, the limited indications may make this superfluous.

Anesthetist expertise

  • These patients are typically healthy, therefore no additional anesthesia experience is necessary.
  • If the patient is an anesthetic risk, extraction should be considered as an option as it may prove a shorter anesthetic. Especially if the practitioner is a novice.
  • Regional nerve block Local anesthesia: intraoral.

Nursing expertise

  • The nurse should be qualified in exposing and developing dental radiographs.
  • Additionally, familiarity with endodontic as well as restorative materials is critical.

Other involvement

  • Consider having a mentor or utilizing a telemedicine site ( www.vetdentalrad.com ) for radiograph review.

Materials required

Minimum equipment

  • High speed air-driven dental drill system.
  • Dental radiology.
  • Autoclave.
  • Eye protection.
  • Burrs: 
    • FG 699, 701, surgical length 701 (cross cut-taper-fissure).
    • Assorted sizes of coarse, round diamond.
    • Fine to ultra-fine cone-shaped diamond.
  • Mineral trioxide aggregate.
  • Sterile paper points.
  • Calcium hydroxide.
  • Schein forceps No. 8 serrated and 202 self-locking.
  • Sterile, dedicated hand piece.
  • Glass ionomer (light cured).
  • Hybrid composite for final resorative.
  • Recent generation bonding agent.
  • Light curing gun. 
  • Finishing disks and burrs as required.

Standard root canal therapy

  • High-speed air-driven dental drill system.
  • Dental radiology.
  • Autoclave.
  • Dental file organizer.
  • Burrs:
    • Round FG: surgical length 2, and 4.
    • Pear shaped FG 330.
    • Fine to ultra-fine cone-shaped diamond.
  • Hedstrom files - 60 mm long/all sizes 15-80.
  • Hedstrom files - 40 mm long/all sizes 90-140.
  • Hedstrom files - 25 mm long/all sizes 15-140.
  • K-reamer - 60 mm long/all sizes 15-110.
  • K-files 31 mm long/all sizes 10-140.
  • Kerr pathfinder files - 25 mm.
  • Premier RC prep cream - chelating agent.
  • Schein forceps No.8 serrated aad 202 self-locking.
  • Gutta Percha points - 31 mm all ISO sizes from 15-140.
  • Paper points -25 mm assorted coarse to fine, 60 mm assorted coarse to fine.
  • 5.25% sodium hypochlorite (household bleach).
  • Endodontic needle 27 g/30 mm and 21 g/45 mm.
  • 5 ml syringe.
  • Root canal plugger/spreader - Henry Schein 608.
  • Kerr's finger pluggers - assorted 21 mm and 25 mm.
  • Kerr's finger spreaders - 21 mm and 25 mm (assorted).
  • Holmstrom pluggers (assorted).
  • Glass mixing slab and spatula.
  • Zinc oxide Eugenol sealer.
  • Sealapex (Kerr) root canal sealer - polymeric calcium hydroxide.
  • Lentulo paste fillers - 29 mm.
  • Hybrid composite for final resorative.
  • Glass ionomer restorative.
  • Recent generation bonding agent.
  • Light curing gun.
  • Finishing disks and burrs as required.

Ideal equipment

  • Heated gutta percha system (sucessfil, obtura II, etc).
  • AH plus, thermaseal, or comparable acrylic sealant.
  • Chloroform, or eucalyptus oil.
  • Digital radiology.
  • Eye loupes.

Optional equipment

  • Rotary endodontic system (Light Speed, Tulsa, etc).
  • Gates Glidden drills - assorted size 1-6.
  • Tubliseal (Kerr) root canal sealer - zinc oxide/eugenol.
  • Mcspadden compactor.
  • Piezo-electric endodontic system.

Preparation

Pre-medication

  • Standard for a mildly painful procedure.
  • A combination of an opiate and NSAID for pain control.
  • Tailor to health of patient.

Dietary preparation

  • Standard pre-operative fasting time.

Site preparation

  • The patient should receive a complete dental prophylaxis.
  • Following that, the tooth should be rinsed with a 0.12% chlorhexidine solution Chlorhexidine (Hexarinse, Virbac).
  • Creating a custom dental dam is ideal.

Other preparation

  • See individual procedures for further details.

Restraint

  • Patient must be under general anesthesia.

Technique

Approach

Step 1 - Access

  • Root canal therapy is initiated by creating proper access to the pulp chamber. In relatively straight feline canine teeth, the fracture site may be appropriate access.

Step 2 - Finding the canal

  • Utilizing a pathfinder, the pulp chamber is gently probed to find the canal(s).

Step 3 - Working length

  • Once the canals have been found, the pathfinder (or a small file) is gently worked to the apex. Once the apex is found (veterinary patients have an apical stop), a dental radiograph is exposed with the file in place to ensure the correct location. If the file is not at the apex, continue working the file until the file reaches the apex. This may require a crown down procedure if the canal is stenotic (see below).

Core procedure

Step 1 - Crown down

  • Using the pre-operative radiograph, determine the approximate master cone. Then, open up the coronal 1/3 of the canal to a point at which it is slightly larger than the master point at that area. This can be done with access shapers or gates gliddens, however the author prefers hand files. This is due to the fact that there is much less breakage with these files.

Step 2 - Cleaning and shaping

  • Using gradually increasing sizes of files, the canal is gradually cleaned and shaped for the final fill. Each file should be GENTLY worked to the working length until the working length is reached. This is best determined using endo-stops. The files should be lubricated with RC prep. 
  • Once working length is obtained, the next file size up is used. This is continued until the file binds in the canal. When the largest file goes to the apex, a radiograph is exposed. This is the master file radiograph. The file should fully fill the canal.

Step 3 - Lavage

  • The canal(s) should be liberally flushed (minimum 1 cc) with sodium hypochlorite (full or 1/2 strength) between each file size. This should be performed with a side-port endodontic needle. In addition, the needle should NEVER be bound in the canal. This may cause forcing of the lavage solution into the periapical space which results in significant morbidity.

Step 4 - Obturation

  • The master file is removed and a gutta percha cone is placed within the canal. Again, a radiograph is exposed to ensure that this fills the apex.  Once this is ascertained, the canal(s) are flushed and dried with sterile paper points.
  • The cleaned and dried canals are then obturated with a combination of gutta percha and sealer cement.
  • There are numerous options of sealer cement including acrylic resin, calcium hydroxide, ZOE, and medicated sealers. This author prefers acrylic sealers (unless there is apical pathology, then he will choose Calcium Hydroxide).
  • There are likewise many options for obturation. These include cold gutta percha techniques where the master point is placed in the canal and then accessory cones placed along side (lateral compaction) and heated gutta perch techniques where the canal is filled with softened gutta percha (vertical condensation). In addition, there is a combination of the above with a heated spreader, as well as thermomechanical condensation (McSpadden).
  • Regardless of the method chosen, the goal of obturation is a homogenous fill through the canal with no voids! 
  • Obturation is initiated by coating the canal with sealer cement and then adding the gutta percha. After obturation, a radiograph is exposed to ensure a complete fill. If the fill is not excellent, the therapy will fail and result in continued pain and infection. Perfection is REQUIRED.

Exit

Step 1 - Restoration

  • Following the radiograph which proves complete obturation, the access sites and fracture site are restored. The access sites are carefully cleaned with a bur and then filled with a hybrid composite restorative and late generation bonding agent. 
  • The tooth is then smoothed with a diamond bur or finishing disk and a final radiograph exposed  Teeth: maxillary canine root canal final fill - radiograph .

Aftercare

Immediate Aftercare

Monitoring

  • Standard post-operative care.

Analgesia

  • NSAID for 3-5 days (pending pre-operative work-up).

Antimicrobial therapy

  • Broad spectrum antibiotic for 7 days (controversial).

Wound Protection

  • Standard post-operative care.
  • Soft food for 2 weeks.

Potential complications

  • Hypochlorite accident.
  • Failure.

Long term Aftercare

Follow up

  • Recheck dental radiographs must be obtained 6-9 months after surgery and then regularly thereafter (annual is recommended).
  • This is critical as veterinary patients rarely exhibit outward signs of failed endodontic procedures.
    Lack of endodontic therapy or poorly performed endodontic therapy will result in continued pain and infection.

Outcomes

Complications

  • Endodontic infection.
  • Abscessation.
  • Future crown fracture.

Reasons for treatment failure

  • The vast majority of time failure is due to improper procedure.
  • For VPT it is generally marginal microleakage from the restoration.

Prognosis

  • VPT: very good prognosis when performed on an intact tooth, 88% if performed on a fractured tooth within 48 hours, poor if exposed greater than 48 hours
  • Standard RCT: if performed correctly, has an excellent long term prognosis. If incorrectly, very poor prognosis.
  • Surgical RCT: if performed correctly, has an excellent long term prognosis. If incorrectly, very poor prognosis.

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Girard N, Southerden P, Hennet P (2006) Root canal treatment in dogs and cats. J Vet Dent 23 (3), 148-160 PubMed.
  • Niemiec B A (2006) Surgical endodontic therapy of the mandibular canine tooth. J Vet Dent 23 (1), 62-66 PubMed.
  • Niemiec B A (2005) Fundamentals of Endodontics. Vet Clin North Am Small Anim Pract 35 (4), 837-868, vi PubMed.
  • Niemiec B A (2005) Dental radiographic interpretation. J Vet Dent 22 (1), 53-59 PubMed
  • Verstraete F J, Kass P H, Terpak C H (2005) Diagnostic value of full-mouth radiography in cats. Am J Vet Res 59 (6), 692-695 PubMed.
  • Mulligan T W & Niemiec B A (2001) Endodontic treatment of vital pulp tissue. Clin Tech Small Anim Pract 16 (3), 159-167 PubMed
  • Niemiec B A (2001) Treatment of mandibular first molar teeth with endodontic-periodontal lesions in a dog. J Vet Dent 18 (1), 21-25 PubMed.
  • Niemiec B A, Mulligan T W (2001) Vital pulp therapy. J Vet Dent 18 (3), 154-156 PubMed.
  • Niemiec B A (2001) Assessment of vital pulp therapy for nine complicated crown fractures and fifty-four crown reductions in dogs and cats. J Vet Dent 18 (3), 122-125 PubMed.
  • Niemiec B A (2000) Management of a complicated maxillary fourth premolar crown-root fracture in a dog. J Vet Dent 17 (3), 128-133 PubMed.

Other sources of information

  • Perry R (2012) The Endodontic Armamentarium. In: Niemiec B A (ed)Veterinary Endodontics. San Diego: Practical Veterinary Publishing, pp 25-61.
  • Cohen S, Hargreaves K M (eds) Pathways of the Pulp. Missouri: Mosby Elsevier.
  • Holmstrom S E, Frost Fitch P, Eisner E R (2004) Veterinary Dental techniques for the Small Animal Practioner. Philadelphia: Saunders.
  • Wiggs R B, Loprise H B (1997) Veterinary Dentistry Principles and Practice. Philadelphia: Lippincott-Raven.
  • www.vetdentalrad.com
  • www.dogbeachdentistry.com