Accessssssssssssssssssssssssssssssssssssssssssssssssssssssssss 2.pptx

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1. ACCESS CAVITY PREPARATION 2

2. Maxillary Lateral Incisor Average length 22.0mm The radicular cross-sectional pulp chamber varies from ovoid at the cervical to round at the apical foramen The apical foramen is generally closer to the anatomic apex than in the maxillary central But may be found on the lateral aspect within 1 or 2 mm of the apex.

3. On rare occasions, access is complicated by a dens in dente

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5. Maxillary Canine Average length 26.5mm The longest tooth in the dental arch The access cavity corresponds to lingual crown shape and is ovoid To achieve straight-line access one often must extend the cavity incisally ,but not so far as to weaken the heavily functioning cusp Initial access is made slightly below midcrown on the palatal side

6. The radicular canal is reasonably straight and quite long. The apex will often curve in any direction in the last 2 or 3mm. Later and accessory canals occur less frequently than in the maxillary incisors The apical foramen is usually close to the anatomica apex but may be laterally positioned .

7. Maxillary First Premolar Average length:20.6mm Most commonly bi rooted The canal orifices lie below and slightly central to the cusp tips. The initial opening is in the central fossa and is ovoid in the buccal -palatal dimension. When one orifice has been located ,the clinician should look carefully for a developmental groove leading to the opening of another canal

8. Radicular irregularities consist of fused roots with separate canals, fused roots with interconnections or “webbing” fused roots with a common apical foramen. The apical foramen is usually closed to the anatomic apex.

9. Maxillary Second Premolar Average length:21.5mm Usu one root with one canal The clinician must assume that the root has two canals until proved other wise. The basic outline of the tooth is slightly ovoid but wider from mesial to distal than outline of the first premolar Radicular morphology may present two separate canals, two canals anastomosing to single canal,or two canals with interconnections.

10. Accessory and lateral canals may be present,but less often than in incisors. In the maxillary molars, the access cavity is rhomboid in shape. The initial trepanation begins in the center of the occlusal surface, tilting the bur toward the mesiopalatal cusp, because the pulp chamber is most expansive here . Once the pulp chamber is encountered ,the bur is moved buccally in contact with the pulpal floor in order to remove any overhanging enamel.

11. The walls of the acess cavity diverge coro This permits straight and direct access for the root canal instruments

12. Maxillary First Molar Average length:20.8mm for each root Three individual roots The palatal root, which is the longest, and the distal- buccal and mesio-buccal roots ,which are about same length. The palatal root is often curved buccally in its apical third .and of the three canals, it offers the easiest access and has the largest diameter.

13. Its orifice lies well toward the palatal surface Its sharply angulated away from the midline. Cross- sectionally its flat and ribbon like. The distal- buccal root is conical and usually straight ,it invariably has a single canal. The mesial-buccal root has a second ML canal was contained in the coronal half of 95.2% of the mesio-buccal roots.

14. Maxillary Second Molar Average length: 20.0 mm for each root. Closely resembles the maxillary first molar, Roof of the pulp chamber rhomboidal in cross section . The distinguishing morphologic feature of the maxillary second molar is three roots grouped close together and sometimes fused. The mesial-buccal root has one canal .

15. Mandibular teeth

16. Mandibular Central and lateral Incisor Average length:20.7mm Narrow and flat in the labial-lingual dimension Smaller fissure burs and small round burs for access The access cavity should be ovoid ,with attention given to lingual approach Frequently the mandibular incisor have two canals

17. The ribbon-shaped canal is common enough to be considered normal and demands special attention in cleaning and shaping apical curvatures and accessory canals are common in mandibular incisors.

18. Mandibular Canine Average length 25.6 mm wider mesial -distally than the incisors. The unusual occurrence of two roots The access cavity is ovoid and may be extended incisally for labial-lingual accessibility The canal is somewhat ovoid at the cervical, becoming round at midroot One root ,one canal

19. Mandibular First Premolar Average length 21.6 mm The coronal anatomy consists of well-developed buccal cusp and a small or almost nonexistent lingual outgrowth of enamel . Access is made slightly buccal to the central groove and is directed in the long axis of the root toward the central cervical area. ovoid pulp chamber is reached with endcutting fissure burs and long- shanked no. 4 or 6 round burs. The cross section of the cervical pulp chamber is almost round in a single-canal tooth and is ovoid in two-canal teeth.

20. Mandibular Second Premolar Average length 22.3 mm similar coronally to the first premolar the mandibular second premolar presents less of a radicular problem its crown has a well-developed buccal cusp and much better-formed lingual cusp than in first premolar Access is made slightly ovoid,wider in the mesial -distal dimension.

21. An important consideration that must not be overlooked is the anatomic position of the mental foramen and the neurovascular structures that pass through it The proximity of these nerve and blood vessels when acute exacerbation of mandibular premolars occurs can result in temporary paresthesia from the fulminating inflammatory process Exacerbations in this region seem to be intense and more resistant to nonsurgical therapy than in other parts of the mouth

22. Mandibular First Molar *The shape of the access cavity for mandibular molars is trapezoidal the initial trepanation is performed centrally with the axis of the bur distally because the space above the distal canal easiest to localize. The mandibular first molar seems to be the most frequently in need of endodontic treatment It usually has two roots but occasionally three with two canals in the mesial and one or to on the distal root

23.  The distal root is readily accessible to endodontic cavity preparation and mechanical instrumentation and the clinical can frequently sac directly in to the orifice(s) the canals of the distal root are larger than the mesial root Occasionally the orifice is wide from buccal to lingual This anatomy indicates the possibility of a second canal of a ribbon like

24.   The mesial roots are usually curved with the greatest curvature in mesial-buccal canal The orifices are usually will separated within the mine pulp chamber and occur in the buccal and lingual under the cusp tips if the traditional triangular outline were changed to more rectangular one it would permit better visualization and exploration of a possible fourth canal in the distal root multiple accessory foramina are located in the furcation areas of mandibular molars

25. they are usually impossible to clean and shape directly and are rarely seen except occasionally on postoperative radiographs if they have been filled with

26. Mandibular Second Molar Average length:19.8mm Smaller coronally than mandibular first molar the roots often sweep distally in a gradual curve with the apices close together . Access is made in the mesial aspect of the crown opening extending only slightly distal to the central Groove

27. after peneteration with the end –cutting fissure bur, the long shanked round bur is to sweep outwardly until unobstructed access is achieved. The shape of distal orifice a narrow , ovoid opening indicates a ribbon-shaped distal canal

28. Guidelines for access cavity prepration

29. 1:Rough out the access cavity well into the dentin, close to the chamber ,with high speed handpiece

30. 2:unroof the chamber with a high speed bur

31. 3:locate canal orifices with the endodontic explore. 4:confirmed canals by penetrating them with small(no.15 and 25)files to determine potency. 5:remove dentin shelves that usually overlie and obscure canal orifices in molars with 6:log shank,small round or small tapered fissure or diamond bur

32. is prepared through the occlusal or lingual surface nerve through proximal or gingival surfaces it cause inadequate canal instrumentation on resulting iatrogenic errors… ………………………..

33. Maxillary premolars Have 2 canals This dictates a broad buccolingual access from that is somewhat constrained in the mesiodistal dimension. the maxillary premolar accesses is never round

34. The maxillary First Molar Mb canal is located under the mesial buccal cusp. the MBZ canal is located mesial to a line from the MB canal toward the palatal canal. the DB canal is located distal to the MB canal in the buccal groove area,slightly lingual to the Mb canal (see figure 2-25,G). The palatal canal is generally the largest canal and is located under the mesiolingual (ML) cusp

35. although these general principles apply to maxillary second molar , chamber may be narrow

36. One or two canals

37. Mandibular Molars access that is placed more toward the mesial half of the tooth and may extend buccal