2nd prelims

• Access preparation

  1. Most important phase of the technical aspects of root canal treatment.
  2. Proper access preparation maximizes cleaning, shaping, and obturation.
  3. Objectives
• Objective of Access Preparation:

  • Straight - line access

  1. Improved instrument control, with less

  -zipping,

  -transportation, or 

  -ledging.

  (2) Improved obturation.

  (3) Decreased procedural errors, such as ledges or perforations.

  (4) Requires adequate tooth structure removal.
• Objective of Access Preparation:

  • Conservation of tooth structure

  (1) Minimal weakening of the tooth.

  (2) Prevention of accidents.
• Objective of Access Preparation:

  • Unroofing of the chamber to expose orifices and pulp horns.

  (1) Maximum visibility.

  (2) Prerequisite in locating orifices of canals.

  (3) Improved straight-line access.

  (4) Exposure of pulp horns.
• Instruments for cleaning and shaping:

  1. Gates-Gliddon: long thin shaft with parallel walls and short cutting head, side cutting with safety tips. - Used to preenlarge coronal canal areas; cut dentin as they are withdrawn from canal.

  2. K-files: twisted square or triangular metal blanks along their long axis; partly horizontal cutting blades. -Can be used with the watch winding or balanced forces technique

  3. Hedstrom files: spiraling flutes cut into the shaft of round, tapered, stainless steel wire; very positive rake angle. - Cut in one direction only— retraction.
• Instruments for cleaning and shaping

  4. Barbed broaches: sharp, coronally angulated barbs in metal wire blanks.

  • Used to remove vital pulp from root canals, severe pulp at constriction level, and remove materials from canals.
• Instruments for cleaning and shaping

  5. Nickel-titanium rotary instruments—designs vary in tip sizing, taper, cross section, helix angle, and pitch.

  1. Important properties— superelasticity and high resistance to cyclic fatigue, which allow continuously rotating instruments to be used in curved root canals.
  2. Nickel-titanium instruments have reduced incidence of blocks, ledges, transportation, and perforation but are believed to fracture more easily than hand instruments.
  3. Examples—EndoSequence, Lightspeed, ProFile, ProTaper, EndoSequence.
• Working length determination:

  1. Reference point selection: Select a point that is stable and easily visualized.
• Working length determination:

  1. Reference point selection: Select a point that is stable and easily visualized.
  2.   Techniques for determining working length.

  • Estimate working length with a diagnostic film taken using a paralleling technique with a No. 10 or 15 K-file.
  • If necessary, correct the working length by measuring the discrepancy between the radiographic apex and tip of file. Adjust to 1 mm short of the radiographic apex.
• Techniques for determining working length

  • Use an apex locator—an electronic instrument used to assist in determining the root canal working length or perforation; operates on the principles of resistance, frequency, or impedance.
  • Feel for the apical constriction (TB?); however, in many instances, this may be unreliable.
• Cleaning and shaping

  1. Best indicator of clean walls is the level of smoothness obtained.
  2. In shaping, it is best to precurve inflexible files because essentially all canals are curved.
  3. Taper of canal permits débridement of apical canal, reduces overinstrumentation of the foramen, and improves ability to obturate.
• Techniques:

  1. Crown-down: clinician passively inserts a large instrument into the canal up to a depth that allows easy progress. The next smaller instrument is used to progress deeper into the canal; the third instrument follows, and this continues until the apex is reached. Hand and rotary instruments may be used in this technique.
  2. Step-back: working lengths decrease in stepwise manner with increasing instrument size.
• Apical preparation

  Apical stops help confine instruments, materials, and chemicals to the canal space and create a barrier against which gutta-percha can be condensed.
• File dimensions:

  • D1: file size at the tip of the file (e.g., 0.08 mm for a size 8 file; 0.15 mm for a size 15 file).
  • The diameter of the file where the cutting flutes end (16 mm) is known as D2 or D16.

  1. It is the diameter at the tip plus 0.32 mm 

  (e.g., for 0.02 taper No. 8 file, it is 0.08 mm + [16 mm × 0.02] = 0.40 mm).

  
• Irrigation and medicaments:

  • Sodium hypochlorite (NaOCl).

  1. Indications.

  (1) Disinfection of root canals—hypochlorite anion (ClO−).

  (2) Dissolving organic matter—proteolytic material.

  (3) Does not remove smear layer.

  (4) Concentrations vary from 0.5% to 6%.
• Irrigation and medicaments:

  • Sodium hypochlorite (NaOCl)

  (1) Signs and symptoms.

  (a) Instant extreme pain.

  (b) Excessive bleeding from the tooth.

  (c) Rapid swelling.

  (d) Rapid spread of erythema.

  (e) Later—bruising and sensory and motor nerve deficits.
• Irrigation and medicaments:

  • Sodium hypochlorite (NaOCl)


    Treatment.

  (a) Long-lasting local anesthetic.

  (b) Encourage drainage.

  (c) Steroids.

  (d) Cold compresses.

  (e) Antibiotics.

  (f) Analgesics

  (g) Daily follow-up.
• Irrigation and medicaments:

  EDTA: Ethylenediaminetetraacetic acid 


  • Principal ingredient: aqueous solution of 17% EDTA.

  b. Indications.

  (1) Removes inorganic material.

  (2) Removes smear layer.
• Irrigation and medicaments:

  • Chlorhexidine: synthetic cationic hydrophobic and lipophilic molecule that interacts with phospholipids and lipopolysaccharides on the cell membrane of bacteria and enters the cell by changing osmotic equilibrium and is effective at a concentration of 2%. The combination of chlorhexidine and NaOCl forms an undesirable precipitate , parachloroaniline, which is believed to affect the seal of root canal filling.
• Irrigation and medicaments:

  • Calcium hydroxide: Best intracanal medicament available.

  b. Its high pH causes an antibacterial effect (pH 12.5).

  c. It inactivates lipopolysaccharide.

  d. It has tissue-dissolving capacity.
• Obturation of the root canal:

  1. To eliminate all avenues of leakage from the oral cavity or the apical tissues into the root canal system.
  2. To seal within the system any irritants that cannot be fully removed during canal cleaning and shaping procedures.
• Obturation of the root canal:

  • Gutta-percha.

  1. Advantages.

  (1) Plasticity—adapts with compaction to irregularities.

  (2) Easy to manage.

  (3) Little toxicity.

  (4) Easy to remove.

  (5) Self-sterilizing (does not support bacterial growth).
• Obturation of the root canal:

  • Gutta-percha

  Disadvantages

  (1) Gutta-percha without sealer does not seal.

  (2) Lack of adhesion to dentin.

  (3) Elasticity causes rebound to dentin.

  (4) Shrinkage after cooling.
• Endodontic emergencies are usually associated with:

  - pain or swelling or both and require immediate diagnosis and treatment.

  - by pathoses in the pulp or periapical tissues.

  - luxation, avulsion, or fractures of the hard tissues.
• Endodontic emergencies:

  • Categories.

  1. Pretreatment.

  a.Patient usually presents with pain or swelling or both.

  b. Challenge in this case is the diagnosis and treatment of the offending tooth.

  2. Emergencies occurring between appointments or after obturation.


  a.Also referred to as “flare-up.”

  b. Easier to manage because the offending tooth has been identified and diagnosed.
• Endodontic emergencies:

  3. Diagnosis


  a. A rule of a true emergency is that only one tooth is the source of pain, so avoid overtreatment.

  b. Obtain a complete medical and dental history.

  c. Obtain a subjective examination relating to the history, location, severity, duration, character, and eliciting stimuli of the pain.
• Endodontic emergencies:

  d. Obtain an objective examination including extraoral and intraoral examinations.

  (1) Observe for swelling, discolored crowns, recurrent caries, and fractures.

  (2) Apical tests include palpation, mobility, percussion, and biting tests.

  (3) Pulp vitality tests are most useful to reproduce reported pain.

  (4) Probing examination helps differentiate endodontic from periodontal disease

  (5) Radiographic examination is helpful but has limitations because periapical radiolucencies may not be present in acute periapical

  periodontitis..
• Endodontic emergencies:

  4. Treatment.

  a.Reducing the irritant, through reduction of pressure or removal of the inflamed pulp or apical tissue, is the immediate goal.

  b. Pressure release is more effective than pulp or tissue removal in producing pain relief.

  c. Obtaining profound anesthesia of the inflamed area is a challenge.
• Endodontic emergencies:

  d. Management of painful irreversible pulpitis.

  (1) Complete cleaning and shaping of the root canals is the preferred treatment.

  (2) Pulpectomy provides the greatest pain relief, but pulpotomy is usually effective in the absence of percussion sensitivity.

  (3) Chemical medicaments sealed in chambers do not help control or prevent additional pain.

  (4) Antibiotics are generally not indicated.

  (5) Reducing occlusion has been shown to aid in the relief of symptoms if symptomatic apical periodontitis exists. 
• Endodontic emergencies:

  e. Management of pulpal necrosis with apical pathosis.

  (1) Treatment is twofold.

  (a) Remove or reduce pulpal irritants.

  (b) Relieve apical fluid pressure when possible.

  (2) When no swelling exists, complete canal debridement is the treatment of choice.
• Endodontic emergencies:

  (3) When localized swelling exists, the abscess has invaded soft tissues.

  (a) Complete débridement.

  (b) Drainage to relieve pressure and purulence— drainage can occur through the tooth or mucosa (via incision and drainage).

  (c) Patients with localized swelling seldom have elevated temperatures or systemic signs, so systemic antibiotics are unnecessary.
• Endodontic emergencies:

  (4) When diffuse swelling exists, the swelling has dissected into fascial spaces.

  (a) Most important is the removal of the irritant via canal débridement or extraction of the offending tooth.

  (b) Swelling may be incised and drained followed by drain insertion for 1 to 2 days.

  (c) Systemic antibiotics are indicated for diffuse, rapid swelling.
• Endodontic emergencies:

  5. Flare-ups

  a.This is a true emergency and is so severe that an unscheduled visit and treatment is required.

  b. A history of preoperative pain or swelling is the best predictor of “flare-up” emergencies.

  c. No relationship exists between flare-ups and treatment procedures (i.e., single or multiple visits).

  d. Treatment generally involves complete cleaning and shaping of canals, placement of intracanal

  medicament, and prescription of analgesic.

  (1) Antibiotics are generally not indicated except in the instance of systemic symptoms and cellulitis.
• Morphologic zones of the pulp: (1) Odontoblast layer (2) Cell-poor zone (3) Cell-rich zone (4) Pulp proper
• ◼Type I collagen is found in skin, tendon, bone, dentin, and pulp.

  ◼ Type II collagen is found in cartilage.

  ◼ Type III collagen is found in most unmineralized connective tissues.

  It is a fetal form found in the dental papilla and the mature pulp.

  ◼ Types IV and VII collagen are components of basement membranes.

  ◼ Type V collagen is a constituent of interstitial tissues.

  ◼ Type VI collagen is a heterotrimer of three distinct chains, α 2 (VI) and α 3 (VI), and is widely distributed in low concentrations in soft

  tissues at interfibrillar filaments.
• What are the classic functions of the pulp?

  1. Formative ( Dentinogenesis)
  2. Nutritive ( Supports in the nutrition/growth of the Avascular dentin)
  3. Protective ( Innervation to the dentin causing sensitivity )
  4. Reparative ( Capability of producing new dentin/ Reparative Dentin)
  5. Defensive ( Triggering inflammatory and immune response)
• DEVELOPMENTAL STAGES ON THE BASIS OF ENAMEL ORGAN

  1. BUD STAGE : 1st epithelial incursion into the ectomesenchyme of the jaw. This is the result of the proliferation of ectomesenchymal cells and migrations of neural crest cells.
  2. CAP STAGE: unequal rate of proliferation hence the resemblance of a cap sitting on a ball of condensed ectomesenchyme, also known as the “dental organ”
  3. BELL STAGE: Further invagination with growth in the margin thus the shape of the bell. This stage assumes the final shape and the formation of the hard tissues of the crown.
  4. ADVANCED BELL STAGE
• What is Pulp?

  Is a soft connective tissue of mesenchymal origin residing

  within the pulp chamber and root canal of teeth (Cohen)

  • Parts of the pulp:

  1. Pulp Chamber

  2. Root Canal/Radicular pulp

  3. Apical foramen

  4. Accessory canals or Lateral

  canal
• Morphologic zones of the pulp:

  1. Odontogenic zone: Presence of odontoblasts in a palisading order

  2. Cell-free (poor) zone (Zone of Weil): Devoid of cells but have few fibers

  3. Cell-rich zone: Contains numerous cells and fibroblasts

  4. Pulp Core (Proper): “Plexus of Raschkow” Contains blood vessels

  and nerves
• TYPE OF CELLS OF THE PULP:

  1. Progenitor Cells
  2. Formative Cells
  3. Fibroblasts
  4. Defensive Cells
  5. Plasma Cells
  6. Lymphocytes
  7. Eosinohilps
  8. Mast Cells