Endo I Final - 1 - Endodontic Access Preparation

  1. ACCESS CAVITY PREPARATION - Major objectives:
    • Remove all the caries
    • Conservation of tooth structure
    • Completely un-roof the pulp chamber
    • Remove all coronal pulp tissue, vital or necrotic
    • Locate all root canal orifices
    • Achieve straight line access
    • Establish restorative margins
  2. Endodontic explorer
  3. Weine’s classification of Root Canal Morphology
    • Type I: 1->1
    • Type II: 1->2->1
    • Type III: 2->2 separate early
    • Type IV: 1->2 separate late; most challenge
    • single canal and single foramen Most of the times
    • Canal form is usually type I
    • The pulp in young patients has usually 3 pulp horns
    • pulp chamber: MD > FL
    • External access outline form: triangular, base toward incisal
    • Lingual shoulder must be removed.
    • single canal & single foramen
    • type I canal form
    • young patients usually have two pulp horns & MD > FL.
    • canal is tapered
    • apex is curved generally distally
    • External access outline form: triangle or oval.
    • Anomalies: Developmental groove, Dens invaginatus.
    • central is shorter than lateral.
    • root canal morphology: Type I more common than II or III.
    • pulp chamber: smaller replica of upper incisors. MD < FL.
    • When single canal, normally straight, but may curve distally.
    • canal outline is oval @ CEJ
    • External access outline form: triangle or oval.
    • Lingual shoulder must be eliminated. A second canal (lingual) may be found underneath.
    • The longest tooth (26.5mm)
    • Pulp chamber: MD < FL.
    • No pulp horn
    • Rarely > 2 canals
    • Oval Type I.
    • Apex tapered and very thin, usually straight but may curve distally.
    • External access outline form: OVAL.
    • Lingual shoulder must be eliminated.
    • Incisal extension of 2-3 mm to incisal edge to allow straight line access.
    • Smaller than the max. canine
    • Type I form; rarely 2 roots; very few times Type IV with 2 separate apical foraminas.
    • MD < FL
    • Access cavity OVAL.
    • Lingual shoulder must be removed. Possible second canal underneath.
    • Incisal extension toward incisal edge for straight line access
    • Root canal: generally 2 roots w/ 2 canals, or 1 root w/ 2 canals w/ a common apical foramen.
    • 2 pulp horns: B and P
    • Pulp chamber: MD < BP
    • Type I (48% ) w/ apical distal curvature.
    • Pulp chamber: MD < BP
    • Two pulpal horns.
    • Canal orifice is in the center
    • One canal 75%, 2 canals 25%
    • - a single canal may bifurcate into two in the apical half
    • Pulp chamber: MDTwo pulpal horns
    • Access preparation in the center of the cusp tips
    • Crown tilted to Lingual; access must start closer to the facial of the occlusal surface
  12. Maxillary First Molar
    • The most complex root canal anatomy.
    • Three individual roots (MB,DB,P).
    • Anatomical structures around the root apices makes radiographic interpretation of the roots difficult.
    • Palatal root: the longest, larger diameter. One canal, curves buccally at apical third, flat, ribbon-like, and wider in MD direction.
    • DB root: conical, 1/2 canals.
    • MB root: Usually two canals (1-3). Concavity on the distal aspect, makes this wall thin.
    • - 37% or more: two MB canals join into one foramen.
    • - 25% or more: two MB canals exit through two separate foramina
    • - MB2 canal always smaller in diameter than the other three.
  13. Maxillary First Molar - Access cavity preparation:
    • Always assume two MB canals exist until careful examination proves not.
    • Rhomboid shape with the corners corresponding to the four orifices (MB1, MB2, DB, P);
    • Mesial: not extend into the mesial marginal ridge.
    • Distal: not penetrate through the ridge.
    • Buccal: parallel to the line connecting MB1 and DB orifices, not to the buccal surface of the tooth.
    • The initial point of penetration: over P, the major (largest) canal - Intrapulpal anesthetic injection can best be utilized in this area when anesthesia is a problem; the easiest to locate.
  14. Maxillary Second Molars
    • Resemble the coronal anatomy of the maxillary first molars
    • Differences:
    • •The roots are closer and sometimes fused; when fused, may have only 2 canals, or one in rare cases.
    • •The roots are shorted and not as curved as MxM1.
    • •Usually each root only has one canal; 4 canals less likely.
    • •The three orifices (MB, DB, P) usually form a flat triangle (sometimes a straight line):
    • - MB is more buccal and mesial
    • - DB is in the midpoint between MB and P.
    • - P is at the most palatal aspect of the root.
  15. Maxillary Second Molars - Access cavity preparation:
    • •Four canals: rhomboid shape.
    • •Three canals: rounded triangle with the base to the buccal.
    • •The oblique ridge usually is not invaded.
    • •The mesial marginal ridge is not invade.
    • •Two canals: oval, widest in the FL dimension.
  16. Mandibular First Molar
    • Most frequent for RCT.
    • Four pulp horns: MB, ML, DB, DL.
    • Two or three roots.
    • Distal surface of M root and mesial surface of D root have root concavities, very thin walls - danger zones.
    • Three or four canals: two in M root (MB and ML canal) and one (Distal canal) or two (DB, DL canal) in D root
    • All Orifices: usually in the mesial two thirds of the crown .
    • Pulp chamber floor: trapezoid or rhomboid shape.
  17. Mandibular First Molar - Distal root:
    • Flattened MD morphology with complex root canal configuration.
    • Conical distal roots: frequently single canal.
    • Diameter larger than mesial root.
    • Occasionally, orifice extends wide bucco-lingually.
    • Wide BL anatomy: indicates a second canal or ribbon-like complex webbing.
    • When two separate canals: much thinner than a single distal canal, and located towards buccal and lingual. When a distal canal can not accommodate size #15 file at the initial entrance and is not centrally located, be suspicious of two distal canals.
  18. Mandibular First Molar - Mesial root:
    • Wider than Distal.
    • Curves mesially from the cervical line to the middle third and then angles distally to the apex.
    • Often two independent foramina.
    • MB canal always curved, ML canal usually straight and shorter.
  19. Mandibular First Molar - Access cavity preparation:
    • Mesial: not to invade the marginal ridge.
    • Distal: allow straight line access to the distal canal(s).
    • MB orifice: commonly under MB cusp.
    • ML orifice: lingual to the central groove.
    • Middle mesial canals may be present between MB and ML orifices (1% to 15% of the time).
    • If only one distal canal: oval buccolingually and located distal to the buccal groove.
    • Initial point of penetration: over the major (largest, distal) canal: Effective Intrapulpal anesthetic injection; the easiest to locate.
  20. Mandibular First Molar - variation in root morphology
    Extra distolingual root (common in Asian population). Radix entomolaris (RE): supernumerary root located distolingually in mandibular molars. Each root usually contains a single root canal.
  21. Mandibular Second Molar
    • Smaller coronally than M1 and more symmetrical.
    • Two roots, close to each other, sometimes fused.
    • Pulp chamber and canal orifices are not as large as MdM1.
    • One, two, three or four canals.
    • Mesial canals: are located closer together.
    • Mesial root: less curvature than MdM1; somewhat shorter.
    • Easier to treat mechanically.
    • Slight mesial inclination -> angle of approach is somewhat easier.
    • Anatomy variations: some single or fused roots have C-shaped canal; the two canals are connected by a semicircular slit.
  22. Mandibular Second Molar - access cavity
    • Similar to MdM1, a little more triangular and less rhomboid.
    • Sometimes only two canals, one M & one D, orifices nearly equal in size and line up in the center of the occlusal surface.
  23. Third Molars (Maxillary And Mandibular)
    • Occasionally, the loss of M1 & M2 makes M3 a strategic abutment for fixed/removable appliances.
    • Can present problems for RCT, mostly related to accessibility and anatomy.
    • Reaching the most posterior tooth with a handpiece and hand instrument can be difficult because of poor visibility and the restricted jaw opening.
    • Often tipped mesially - to the advantage of the clinician.
    • Keeping in mind the long axis of the tooth and pulp chamber is centrally located will assist in the initial cavity preparation.
  24. Molar Access Opening Errors
    • Unroofed preparation: The pulpal horns have merely been exposed and the entire roof of the pulp chamber remains.
    • Over extended preparation: undermining the enamel walls; The crown is badly gouged due to the failure to observe recession in the radiograph.
    • Perforation into the furcation: using a surgical length bur and failing to realize the narrow pulp chamber had been passed.
    • Inadequate vertical preparation: failure to recognize severe buccal inclination of an unopposed molar.
    • Perforation at the mesial cervical: failure to orient the bur with the long axis severely tipped to the mesial (mandibular molars)
    • Disoriented occlusal outline form exposing only the palatal canal: The faulty cavity has been prepared in a full crown which was placed to “straighten” a rotated molar.
    • Disoriented occlusal outline form exposing only the mesiobuccalcanal: The faulty cavity has been prepared in a full crown which was placed to “straighten-up” a lingually-tipped molar.
    • Failure to find the second distal canal: lack of exploration for the fourth canal.
Card Set
Endo I Final - 1 - Endodontic Access Preparation
Endo I Final 1 - Endodontic Access Preparation