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Tooth Morphology and Access Openings

Tooth Morphology and Access Openings. RELATIONSHIP OF TOOTH MORPHOLOGYAND ACCESS CAVITY PREPARATION. The visual. Access preparations. The assumed. A investigation of the sulcus , coronal clefts, restorations, tooth angulation,cusp position, occlusion. mandatory before access.

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Tooth Morphology and Access Openings

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  1. Tooth Morphology and Access Openings RELATIONSHIP OF TOOTH MORPHOLOGYAND ACCESS CAVITY PREPARATION

  2. The visual Access preparations The assumed A investigation of the sulcus, coronal clefts, restorations, tooth angulation,cuspposition, occlusion. mandatory before access Palpation of buccal or labial soft tissue will help determine root is the first indication of the assumed and is the first key to the root position and root canal system. The coronal anatomy

  3. Tooth length determination Maxillary Length(mm) Mandibular Length(mm) 20.7 24.0 16.0 21.1 27.0 18.0 25.6 32.5 18.0 Central incisor Average Greatest Least Lateral incisor Average Greatest Least Canine Average Greatest Least 22.5 27.0 18.0 22.0 26.0 17.0 26.5 32.0 20.0 Central incisor Average Greatest Least Lateral incisor Average Greatest Least Canine Average Greatest Least

  4. Maxillary Length(mm) Mandibular Length(mm) First premolar Average Greatest Least Second premolar Average Greatest Least Second premolar Average Greatest Least First premolar Average Greatest Least Second premolar Average Greatest Least 20.6 22.5 17.0 21.5 27.0 16.0 21.6 26.0 18.0 22.3 26.0 18.0 Second premolar Average Greatest Least 21.5 27.0 16.0 22.3 26.0 18.0

  5. First molar Average Greatest Least Second molar Average Greatest 1 .east Third molar Average Greatest Least First molar Average Greatest Least Second molar Average Greatest Least Third molar Average Greatest Least 20.8 24.0 17 0 20.0 24.0 16.0 17.1 22.0 14.0 21.0 24.0 18.0 19.8 22.0 18.0 18.5 20.0 16.0

  6. ACCESS CAVITY PREPARATION IN INCISORS are often weakened coronally by excessive removal of tooth structure Incisors, particularly mandibular incisors is often narrower than the bur used to make the initial access. The mesiodistal width of the pulp chamber (cervical or root surface) are common, especially with calcifications. Labial perforations If the incisal edge is intact, it is almost impossible to perforate lingually.

  7. Correct Incorrect A, Sweeping motion in a slightly downward lingualto- labial direction (arrows), until the chamber is engaged, to obtain the best access to the lingual canal. B, Incorrect approach:directing the end-cutting bur in a straight lingual-tolabial direction. Mutilation of tooth structure and perforation will be the result in this small and narrow incisor.

  8. METHODS OF DETERMINING ANATOMIC DETAIL When the radiograph shows that the canal suddenly stops in the radicular region the assumption is that it has bifurcated (or trifurcatcd) into much finer diameters. To confirm this division, a second radiograph is exposed from a mesialangulation of 10 to 30 degrees. The resultant film will show either more roots or multiple vertical lines indicating the peripherics of additional root surfaces A radiograph also reveals many clues to anatomic "aberrations": lateral radiolucencies indicating the presence of lateral or accessory canals an abrupt ending of a large canal signifying a bifurcation aknoblike image indicating an apex that curves toward or away from the beam of the x-ray machine multiple vertical lines, as shown in this curved mesial root , indicating the possibility of a thin root, which may be hourglass shaped in cross section and susceptible to perforation. The endodontic pathfinder inserted into the orifice openings will reveal the direction that the canals take in leaving the main chamber

  9. 4. Digital perception with a hand instrument can identify curvatures, obstruction, root division, and additional canal orifices 5. Fiberoptic illumination can reveal calcifications, orifice location, and fractures 6. Knowledge of root canal anatomy will prompt the clinician always to search for additional canal orifices where they are known to occur—for instance, the usual location of a fourth canal in the maxillary first permanent molar between the mesiobuccal and palatal canals along the developmental groove 7. Further knowledge of root formation can save the clinician difficulties with instrumentation—for example, in what appears radiographically to be a normal palatal root of a maxillary first permanent molar but is actually a root with a sharp apical curvature toward the buccal 8. Ethnic characteristics as well as other physical differences can be manifested in tooth morphology, for example, the common occurrence of four canals in Asian peoples

  10. Average time of eruption: 7 to 8 years Average age of calcification: 10 years Average length: 22.5 mm

  11. Curved accessory canal with straight lateral canal intersecting. Parallel accessory canal to main canal with simple lateral canal. Double lateral canals

  12. Maxillary Lateral Incisor Average time of eruption: 8 to 9 years Average age of calcification: 11 years Average length: 22.0 mm

  13. Maxillary Canine Average time of eruption: 10 to 12 years Average age of calcification: 13 to 15 years Average length: 26.5 mm

  14. Canine with multiple accessory foramina. Maxillary canine with lateral canal dividing into two additional canals.

  15. Average time of eruption: 10 to 11 years Average age of calcification: 12 to 13 years Average length: 20.6 mm

  16. Permanent Maxillary First Premolar • Buccolingual Section -The majority of the max. 1st premolar have 2 well developed roots on a common root trunk or. The majority of max. 2nd PM have 2 root canals. A small percentage have 3 roots that may be undetectable radiographically. If one root is present, 2 root canals are also seen, that might join & open in one apical foramen or 2 apical foramina. -The level of buccal pulp horn is more occlusal than the lingual pulp horn. - The pulp chamber floor is below cervical level - Root canals often exit at root tip, or slightly labial or lingual.

  17. Mesiodistal Section • Pulp horns appear blunted. • Pulp chamber can’t be diffrentiated from root canal. • Pulp cavity tapers slightly from occlusal aspect to to apical foramen. • Apical foramen often exit at tip of root, or some at mesial or distal sides.

  18. Cervical Cross Section • Shows the characteristic kidney shaped outline due to the M developmental groove. • Pulp cavity may show constriction adjacent to developmental groove, or may follow outline of root surface. • Some roots will show 2 separate root canals or 3 in case of 3 rooted root canals.

  19. Lateral bony lesion associated with filled lateral canal Two canals fusing and rcdividing. Three canals in maxillary first bicuspid.

  20. Maxillary Second Premolar Average time of eruption: 10 to 12 years Average age of calcification: 12 to 14 years Average length: 21.5 mm

  21. Permanent Maxillary Second Premolar • BuccoilingualSection Most max. 2nd PM have one root & one root canal. 2 roots & 2 root canals may be seen. pulp horns & root canals are very broad in teeth with single canals. pulp horns may be well developed or blunt. In apical half or third , root canal may narrow abruptly.

  22. Some teeth process dentinal islands or bifurcations at the apical third of the root, the clinician must treat this situation as 2 roots. • The apical foramen may exit at the root tip, at buccal or lingual aspects of the root, or at both buccal & lingual aspects.

  23. Mesiodistal Section • Pulp horns are blunt, Pulp cavity tapers slightly from occlusal aspect to apex. • Apical foramen may exit at root tip or anywhere near it.

  24. Cervical Cross Section • Is oval or kidney shaped. • Pulp cavity is either centered in the root, may be constricted in the middle of the canal space, elliptical or entire seperation.

  25. Single canal dividing into two canals. Single canal splitting into three canals. Multiple foramina.

  26. Maxillary First Molar Average time of eruption: 6 to 7 years Average age of calcification: 9 to 10 years Average length: 20.8 mm

  27. Fourth canal in mesiobuccal root; loops and accessory canals Sharp curvature and multiple accessory canals in palatal root (contrast to silver cones in second molar). Second canals in both mesiobuccal and lingual canals.

  28. Maxillary Second Molar Average time of eruption: 11 to 13 years Average age of calcification: 14 to 16 years Average length: 20.0 mm

  29. Four-rooted maxillary second molar Severely curved mesiobuccal root with right angle curve in distobuccal root.

  30. Maxillary Third Molar Average time of eruption: 17 to 22 years Average age of calcification: 18 to 25 years Average length: 17.0 mm

  31. Showing canals fuses into single canal. (Note multiple accessories in second molar.) Distal bridge abutment with major accessory canal.

  32. Mandibular Central and Lateral Incisors Average time of eruption: 6 to 8 years Average age of calcification: 9 to 10 years Average length: 20.7 mm

  33. Mandibular lateral and central, both with two canals. Two-rooted mandibular lateral incisor.

  34. Mandibular Canine Average time of eruption: 9 to 10 years Average age of calcification: 13 years Average length: 25.6 mm

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