Access opening of molar teeth

Access opening-molars

2. Introduction

t. A well designed access preparation is es:

odontic success.

r coronal access forms the
m of pyramid of endodontic
nt. Any improperly prepared
cavity can impair the

ntation, disinfection and

3. Objectives of access cavity preparation
« Direct straight line access to the apical foramen helps in:
- Improved instrument control because of minimal instrument
deflection and ease of introducing instrument in the canal
- Improved obturation
- Decreased incidence of iatrogenic errors.
« Complete deroofing of pulp chamber helps in:
- Complete debridement of pulp chamber
- Improving visibility
- Locating canal orifices
- Permitting straight line access
- Preventing discoloration of teeth because of remaining
pulpal tissue.
«+ Conserve sound tooth structure as much as possible so as to
avoid weakening of remaining tooth structure.

5. |

| | | | Figure 148. bampks d acess
| | | buns Left to gh, No. 4 round
| |

| cate, No. SÉ carbide, Great
White, Beaver bu, Transmetal,
| | Muliparpose bur, Endo Z bar,

and Endo Acces br.

Figure 1412 Mueler bus exhib a round cutting head
attached to a | shank. The shank ts not desi to
dail deep pre eat but pe the head of m
speed handplece away from the tooth and permit bettr
vist.

1 —

* |

Fig 11.21.The bur has finished the walls of the access cavity. gc, 735 a al
Figs 15.10AtoC Access refining burs ving them a sight coronal flare. an i Endodontic ultrasonic unit. (Courtesy SybronEnd

6. » The basic principles of access opening was established by G.V. Black, as

following:

=

> Outline form: The outline form of the endodontic cavity must be

correctly shaped and positioned to establish complete access for
instrumentation, from cavity margin to apical foramen. To achieve
Optimal preparation, three factors of internal anatomy must) be
considered:

2 Pulp chamber size: In young patients, these preparations must be wore
extensive than in older patients, in whom the pulp has receded and4the

pulp chamber is smaller in all three dimensions.

7. B. Pulp chamber shape: The finished outline form
Should accurately reflect the shape of the pulp

chamber. For example, the floor of the pulp chamber in

a molar tooth is usually triangular in shape, owing to

the triangular position of the orifices of the canals.

(©) Number, Position, and Curvature of root canals: To prepare each canal
eificiently without interference, the cavity walls often have to be extended

to allow an unstrained instrument approach to the apical foramen:

> Variations from the normal number of canals:-
1. Maxillary Molars: A second separate canal in the mesiobuccal root.
2. Mandibular molars: A second canal often is found in the distal root.

8. 2. Convenience form: In endodontic therapy, convenience form
makes the preparation and filling of the root canals more convenient
and accurate. The benefits of it are:

A. Unobstructed access to the canal orifice:

» Enough tooth structure must be removed to allow
instruments to be placed easily into the orifice of
each canal without interference from overhanging
walls.

+ The clinician must be able to see each orifice and
easily reach it with the instrument points.

+ Failure to observe this principle not only endangers
the successful outcome of the case but also adds
materially to the duration of treatment.

B. Extension to accommodate filling techniques:

= It's often necessary to expand the outline form to make certain“ filling
techniques more convenient or practical. If a softened gutta-percha technique is
used for filling, where in rather rigid pluggers are used in a vertical thrust, then
the outline form may have to be widely extended to accommodate these heavier
instruments.

9. Sire a7 A, Me ced es sto ve
dent must be removed to acheve straight
access B, The acess completed, €, The ong
‘anal (0) 1s modi by Gate-Gidden burs
moving tooth structure at Band C.

Figs 15.34 and 8 (A) Not removing dentin from mesial wall causes
Baies of instrument while inserting in canal leading to instrumental t
terrors: I Removal of extracieraan ram scoess opening gives SSID

ease alo its beis 1

: A m Mouse hole 7: yeni
+ Extension of orifices to the axial walls results in “mouse hole ®

effect” (Figs 15.33A and B). Per
+ Itis caused because of under extension of the access cavity. wal
+ It results in hindrance to the straight line access which may

further cause procedural errors.

+ Straight line access to canal is confirmed by passing a file
passively into the canal. File should reach the apex or first point
of curvature without any deflection.

10. 3. Removal of the remaining carious dentin and defective restorations: The
advantages of its removal are:

A.

B.

To eliminate mechanically as many bacteria as possible from the interior
of the tooth.

To eliminate the discolored tooth structure, that may ultimately lead fo
Staining of the crown.

4. Debridement of the cavity:

All of the caries, debris, and necrotic material must be removed from the
chamber before the radicular preparation is begun. If the calcified or
metallic debris is left in the chamber and carried into the canal, it may act
as an obstruction during canal enlargement.

Soft debris carried from the chamber might increase the bacterial
population in the canal. Coronal debris may also stain the crown,
particularly in anterior teeth.

Round burs are most helpful in cavity debridement. The long-blade
endodontic spoon excavator is ideal for debris removal. Irrigation with
sodium hypochlorite is also an excellent measure for cleaning the chamber
and canals of persistent debris.

11. Guidelines for access opening

A. Penetration into enamel with No. 2 or No. 4 high speed round bur
B. Exposure of pulp chamber with tapered fissure bur

C. Refinement of the pulp chamber and removal of pulp chamber roof
using round bur from inside to outside

D. Complete debridement of pulp chamber space

Clinical Tips

- Recommended access opening bur is round bur. It prevents
the overpreparation. Once “drop in” into the pulp chamber is
obtained, round bur is replaced by tapered fissured bur.

+ Avoid using flat ended burs as these result in highly irregular
access walls, causing multiple ledges.

12. 1.

2.

The authors proposed six guidelines (laws) of pulp chamber anatomy to
help clinicians to determine the number and location of orifices on the
chamber floor. More than 95% of examined teeth by the investigators
were conformed to these laws.

Centrality: Floor of pulp

chamber is always located in \ € de
the center of tooth at the level ;

of CEJ junction.

Concentricity: Walls of pulp chamber are

always concentric to external surface of

tooth at the level of CEJ, that is, the
external root surface anatomy reflects the ’ = |

internal pulp chamber anatomy.

13. 3. CEJ: The distance from the external surface of the clinical crown to the wall
of the pulp chamber is the same throughout the circumference of the tooth at
the level of the CEJ, making the CEJ is the most consistent repeatable

landmark for locating the position of the pulp chamber.

4 Color change: The pulp chamber floor is always darker in color than thewallsé

FR
94

14. enter of the pulp chamber floo:

16. à i
AG 753, pm Td br sun ep ot po hr, hr tn

FIG. 7-51 A, Mestal and distal boundary of a maxillary molar showing,

RU Ml a dey colore ara sl ee cd hm,

mandibular molar showing the acces starting locaton (X). D, Dista: yds de D À lt perl aad br sl bc ol ol he cs apa de

M, mestal; MB, mesiobuccal; ML, mestolingual. ik

17. The shape of pulp chamber is rhomboid
with acute mesiobuccal angle, obtuse
distobuccal angle and palatal right angles.

Palatal canal orifice is located palatally.
Mesiobuccal canal orifice is located under
the mesiobuccal cusp. Distobuccal canal
orifice is located slightly distal and palatal to
the mesiobuccal orifice. A line drawn to
connect all three orifices (MB, DB, P) forms
a triangle, termed as molar triangle.

NY)
He

Figs 15.36A to C Different patterns of molar triangle

Generally 3 roots with 3 canals , additional canal is located in MB root.
Large pulp chamber triangular in shape with the base toward the buccal and

the apex toward the palatal surface.

18. Average length: MB= 20mm, DB=19.5mm, P=20.5mm.

MB canal opening is closer to buccal wall than DB orifice.

DB canal is closer to the middle of the tooth than to the distal wall , and it is
shorter and finest of the 3 canals.

Almost always a second mesiobuccal
canal, i.e. MB2 is present in first
maxillary molars, which is located
palatal and mesial to the MB1.
Though its position can vary
sometimes it can lie a line between
MB1 and palatal orifices.

7 tf re Ds

Because of presence of MB2, the ee P
access cavity acquires a rhomboid B
shape with corners corresponding to Figs 9.4A and B 0 n of
all the canal orifices, i.e. MB1, MB2,
DB and P.

19. FIG. 7-101 The two locations of the second mestobuccs! (MB-2) canal orifice: in a maxillary int molar. 5. Buccal: D, distal: M. mental

21. + Studies of apical canal configurations for the MB root

Author(s) Type of Study Country Ono Canal (%)* Two Canals (%)' Three Canals (%)
Vertucei™™ Clearing USA 82 (17) 18 =
Pineda and Kurtler"®? Radiographic Mexico 51.5 (12.2) 48.5 (12.8) _
Caliskan et al” Clearing Turkey 75.4 (41) 24.6 (1.6) =
Acousta Vigouraux and Ground section and Chili 28.4 69.3 2.3
Trugeda Bosaans* magnification
Seidberg et ar Sections usa 75 (37) 25 =
Weine et al?= Sectioning usa 86 (37.5) 14 =
Stropko'” Clinical (microscope) USA 45.1 (38.1) 540 =
Fogel et al en Canada 68.3 (39.4) 31.7 =
Pomeranz and Fishelberg'® Clearing usa s2 2m 48 _
Kulild and Peters" In vitro (microscope) usa 41 (38.6) 59 (2.4) =
Thomas et al?® Radiographic USA 73.6 (27.3) 26.4 (12) =
Neaverth et al Clinical 37.7 (16.7) 61.9 (1.8) 0.4
Weine er al“ Radiographs with files Japan 66.2 (24.2) 33.8 (3.4) =
Gilles and Reader” SEM and microscope usa 61.9 (52.4) 38.1 (4.8) _
Pecora et alt= Clearing Brazil 92.5 (17.5) 75 =
Hartwell and Bellizzi™* Clinical (mesiobuccal root of USA 814 18.5 ==
maxillary first molar)
Weller and Hartwell?™ Radiograph of root canal teeth USA 61 39 =
Wasti et al Clearing Pakistan 56.6 (23.3) 43.4 (13.3) =
al Shalabi et al? Clearing Ireland 36.4 (15.9) 62.6 (6.1) 1

Bond et al?
Bearty®

Maggiore et al
Cecic et al”
Baratto-Filho et al’?
Wong?"

Alavi et alt

Sert and Bayirli™

Ng et aro
Zaatar et al’

Sykaras and Economou””
Imura et al?

Nosonowitz and Brenner"?
Pattanshetti et al"

Smadi and Khraisar'”

Rwenyonyi et al”?

Clinical
Clinical
en
Clearing

Clearing (men)
Clearing (women)
Clearing

Radiographs of root canal
teeth

Radiographs and microscope
Clearing

en
Clinical

Clearing

Clearing (mesiobuccal root)
Clearing {distal buccal root)

ical

USA
USA
Brazil
USA
Thailand
Turkey
Turkey
Burma
Kuwait

Greece
Japan
USA
Kuwait
Jordan
Uganda
Uganda

91 (23)
11.8
849

100 (41.8)
53 (30)
80.1 (5)
98.2 (0.5)

Case report
Case report
Case report

46.2
34 (6)
43 (16)
ait
15

o
882

15.1
27101
19.4 (9.1)
(1.8)

22. + Studies of apical canal configurations for the DB root

Author(s) Type of Study Country One Canal (%)* Two Canals (%)*

Vertucei?'® Clearing USA 100 =

Pineda and Kuttler'* Radiographic Mexico 96.4 3.6

Caliskan et al” Clearing Turkey 98.4 16

Acosta et al? Ground section and magnification Chili 100 =

Thomas et al” Radiographic USA 96.7 (0.5) 3.3

Pecora et al!® Clearing Brazil 100 =

Wasti et al?” Clearing Pakistan 83.3 16.7

al Shalabi et al? Clearing Ireland 97.5 25

Martinez-Berná and Ruiz-Badanelli'* Clinical Spain = Case reports (3)

Hulsmann* Clinical Germany — Case report

Bond et al Clinical Pakistan _ Case report

Beatty” Clinical USA Case report _

Maggiore et al'® Clinical USA Case report =

Cecic et al” Clinical USA Case report _

Baratto-Filho et al" Clinical Brazil Case report _

Wu et al? Clinical USA Case report -

Alavi et al! Clearing Thailand 100 _

Sert and Bayirli™ Clearing (men) Turkey 97 (6) 2(1)
Clearing (women) Turkey 96 (7) 4

Ng et al Clearing Burma 97.8 11

Zaatar et al”? Clearing Kuwait 100 _

23. + Studies of apical canal configurations for the P root

Author(s) Type of Study Country One Canal (%)* Two Canals (%)° Three Canals (%)*
Vertucci?® Clearing USA 100 _ _

Pineda and Kuttler'® Radiographic Mexico 100 = _

Caliskan et al Clearing Turkey 96.7 33.3 =

Acosta et al? Ground section and Chili 100 _ _

magnification

Thomas et al?® Radiographic USA 99.1 (0.9)! 0.9 =

Pecora et al'®® Clearing Brazil 100 _ _

Wasti et al??? Clearing Pakistan 66.7 33.3 _

al Shalabi et al? Clearing Ireland 98.8 12 =
Martinez-Berná and Clinical Spain Three case reports — =

Ruiz-Badanelli'?

Bond et al” Clinical Pakistan Case report (100) ~ —

Beatty” Clinical USA Case report = =
Maggiore et al Clinical USA = = Case report
Cecic et al” Clinical USA _ Case report —
Baratto-Filho et al” Clinical Brazil = Case report =

Wong?” Clinical USA = = Case report
Thews et al?” Clinical USA ml Two case reports —

Christie et al*' Clinical Canada _ Two case reports _

Alavi et al* Clearing Thailand 100 _ _

Sert and Bayirli'* Clearing (men) Turkey 97 (3) 3 =

Clearing (women) Turkey 95 2 (2) 3(3)

Ng et alt" Clearing Burma 100 = _

Zaatar et al?” Clearing Kuwait 100 — =
Barbizam et al" Clinical Brazil = Case report =
Gopikrishna et al” Clinical (spiral computed India = Case report =

tomography}

24. Maxillary Second Molar

Fi 12. Acs cay fan upper i
pp ca cc ap eo

al orifice is
towards

25. + Studies of apical canal configurations for the MB root

Three Four

Author(s) Type of Study Country One Canal (%)* Two Canals (%)' Canals (%) Canals (%)
Vertucci?"® Clearing USA 88 (17) 12 = =
Pineda and Kuttler'* Radiographic Mexico 72.8 (8.2) 27.2 (14.4) = =
Caliskan et al? Clearing Turkey 68.7 (23.6) 27.1 (4.2) 42 =
Pecora et al" Clearing Brazil 80 (22) 20 _ _
Gilles and Reader® SEM and light USA 62 (32.4) 38 (2.7) = —

microscopy
Stropko'* Clinical (microscope) USA 78 (45.6) 22 _ _
Eskoz and Weine” Radiographic 80.6 (20.9) 19.4 (3) = =
Pomeranz and Fishelberg'® Clinical USA 75.9 (13.8) 24.1 = —
Nosonowitz and Brenner“? Clinical USA 94.4 (25.5) 5.6 = =
al Shalabi et al? Clearing Ireland 50 (5.6) 50 (16.7) nd —
Benenati* Clinical USA Case report = = =
Fahid and Taintor* Clinical USA Case report _ _ _
Sert and Bayerl'* Clearing (men) Turkey 71 (45) 28 1 _

Clearing (women) Turkey 81 (25) 18 _ 1

Kulild and Peters'® In vitro (microscope) USA 54.2 45.8 _ _
Alavi et alt Clearing Thailand 53.8 44.6 = 1
Zaatar et al” Radiographs of root Kuwait 93.5 (17.4) 6.5 re a)

canal teeth
Imura et al Clearing Japan 30 70 _ _
Ng et alte Clearing Burma 74 26 = =
Rwenyonyi et al'” Clinical (mesial root} Uganda 88.7 (1.8) 11.7 (5) = =

Clinical (distal Uganda 99.5 (0.5) aa =
buccal root)

Clinical (palatal root) Uganda 99.5 (0.5) (0.5) = =

26. + Studies of apical canal configurations for the DB root

Author(s) Type of Study Country One Canal (%)* Two Canals (%)
Vertucei?'® Clearing USA 100 _
Pineda and Kuttler'® Radiographic Mexico 100 -
Caliskan et al” Clearing Turkey 100 =
Pecora et al! Clearing Brazil 100 _
al Shalabi et al? Clearing Ireland 100 _
Benenati”* Clinical USA Case report =-
Fahid and Taintor* Clinical USA _ Case report
Sert and Bayirli'™ Clearing (men) Turkey 100 (2) -

Clearing (women) Turkey 100 (2) =
Zaatar et al Radiographs of root canal teeth Kuwait 100 =
+ Studies of apical canal configurations for the P root
Author(s) Type of Study Country One Canal (%) Two Canals (%) Three Canals (%)
Vertucci® Clearing USA 100 = _
Pineda and Kuttier'® — Radiographic Mexico 100 _ _
Caliskan et al? Clearing Turkey 97.9 2.1* =
Pecora et al'** Clearing Brazil 100 _ _
al Shalabi et al? Clearing Ireland 100 = =
Benenati”* Clinical USA = Case report _
Sert and Bayirli'® Clearing (men) Turkey 100 _ _

Clearing (women) Turkey 100 = =

Zaatar et al” Radiographs of root canal teeth Kuwait 100 = ia
Ulusoy and Gorgul”* Clinical Turkey = Case report

Shin et al’® Clinical (microscope) South Korea pare Case report

27. of maxi

cess opening
er ym molar

28. Figure 5-50. Operative errors—maxillary molars. One of the most common
errors is perforation of the furcation while searching for a receded pulp with
a surgical-length bur. Wider access helps prevent these accidents, as does
measuring the depth on the radiograph. These perforations may be repaired
with placement of mineral trioxide aggregate (MTA, Dentsply/ Tulsa).

Figure 5-53. Operative errors—maxillary molars. Perforation of a palatal root
is commonly caused when the clinician assumes the canal is straight and fails to
explore and enlarge the canal with a fine, curved instrument. Remember, roots

that curve buccally appear to be straight in buccolingual radiographic projections.

Figure 5-52. Operative errors—
maxillary molars. Inadequate vertical
preparation related to a failure to
recognize the severe buccal inclination
of an unopposed molar.

Figure 5-51. Operative errors —maxillary molars. A, Underextended prepara-
tion. The roof of the pulp chamber has not been removed. The white color of
‘the dentin in contrast to the dark color of the dentin on the floor of the chamber
should be the clue. The pulp horns have barely been nicked, and the clinician
has assumed that the canal orifices have been located. Total control of the
instruments will be lost if instrumentation proceeds through tiny orifices,

B, Example of the failure to remove the roof of the pulp chamber. One can
easily visualize how the interfering tooth structure will control the path of

the instrument.

29. Access opening of
mandibular molars

30. Mesiobuccal orifice is under the mesiobuccal cusp. Mesiolingual orifice is
located in a depression formed by mesial and the lingual walls. The distal
Orifice is oval in shape with largest diameter buccolingually, located distal to
the buccal groove. Orifices of all the canals are usually located in the mesial
two-thirds of the crown.

Distal root has also shown to have more than one orifice, Le. distobuccaly
distolingual and middle distal. These orifices are usually joined by ihe
developmental grooves.

Mhe shape of access cavity is usually trapezoidal or rhomboid.
Average length: 21 mm.

Triangular outline form reflect the anatomy of pulp chamber with the Mase
toward the mesial and the apex toward the distal wall.

31. Starting point of
bur penetration
MB cusp tip

Distal boundary

Mesial boundary

M

ML cusp tip

®
Fig 12.211.8.A tower aight fest molar with a detal canal and
three mesial cansa Access Canty B. Postoperative radiograph
Rodiographically the bere mens! canal sppeat superimpezad,
À B > — y

Fig. 11.112 in this other case, the middie mesial root canal is vi
sble in the apical third of the mesial root (Courtesy of Dr CA
Ruddiei

RG 219 Mal ma ne eg yr la, sung lg 1 |
Ro cora meme cm eme du i nl ad

a mm me À The ed don dd A
ibid fe a ddd 8 ln cpl mm he

32. + Studies of apical canal configurations for the M root

Three Four
Author(s) Type of Study Country One Canal (%)* Two Canals (%)" Canals (%) Canals (%)
Vertucei?'® Clearing USA 40 (28) 59 (8) 1 _
Pineda and Kuttler!®? Radiographic Mexico 43 (30) 57 (7) _ _
Caliskan et al? Clearing Turkey 40 (37) 56.6 (7) 3.4 _
Skidmore and Bjorndal'% Cast resin USA 44.5 (38) 555 — —
Pomeranz et al'® Clinical USA = 16 16 =
Wasti et al”? Clearing Pakistan (23) 737 33 =
Zaatar et al?” Clearing Kuwait 63.3(57) 347 = =
Sperber and Moreau'* Ground sections Senegal (16) 84 = _
Gulabivala et al®® Clearing Pakistan 43 (29) 50 (6) in =
Beatty and Krell” Clinical USA _ _ Case report —
Martinez-Berná and Clinical Spain - _ Case report —
Badanelli®
Fabra-Campos™ Clinical Spain - = Case report —
Baugh and Wallace” Clinical USA — Case report (3 > 2)) — =
Ricucci”* Clinical Italy _ Case report (3 2)) — _
DeGrood and Clinical USA - Case report (3 > 2 — =
Cunningham”

Jacobsen et al* Clinical USA _ Case report (3 — 2)' Case report Case report
Reeh'® Clinical USA _ _ = Case report
Sert and Bayirli'* Clearing (men) Turkey 52 (52) 44 (3) 3 _

Clearing (women) Turkey 49 (46) 5116) _ =
Walker" Radiographic Southern 24 75 1 =

China

da Costa et al” Clearing Brazil 54.6 45.4 _ _
Pattanshetti et al" Clinical Kuwait (100) = = =

33. + Studies of apical canal configurations for the D root

Author(s) Type of Study Country One Canal (%)* Two Canals (%)' Three Canals (%)
Vertucei?'® Clearing USA 85 (15) 15 (8) _
Pineda and Kuttler'* Radiographic Mexico 85.7 (12.7) 14.3 (8.6) =
Caliskan et al Clearing Turkey 81.4 (33) 16.9 (7) 17
Zaatar et al" Clearing Kuwait 83.7 (8) 16.3 =
Sperber and Moreau'* Ground sections Senegal 78 (22) 0.2
Gulabivala et al Clearing Pakistan 83.3 (4) 16 (3) 0.7
Wasti et al”? Clearing Pakistan 56.7 (27) 43.3 (20) =
Skidmore and Bjorndal'" Cast resin USA 88.8 (18) 11.2 _
Ricucci™” Clinical Italy Case report _ _
DeGrood and Cunningham” Clinical USA _ Case report (3 2 —
Martinez-Berná and Clinical Spain Case report (3 > 1)' Case report (3-3 2} —
Badanelli'""

Beatty and Krell? Clinical USA = Case report u
Reeh'® Clinical USA = = Case report
Beatty and Interian”' Clinical USA = = Case report
Friedman et al® Clinical Israel - _ Case report
Stroner et al'* Clinical USA _ _ Case report
Sert and Bayirli'* Clearing (men) Turkey 89 (36) 9(3) 2

Clearing (women) Turkey 85 (31) 15 (2) =
Walker? Radiographic Southern 72 28 =

China

da Costa et al”? Clearing Brazil 90.5 9.5 =
Pattanshetti et al'®? Clinical Kuwait 95.5 (40) 45 =

34. * Access opening of mandibular second molar is similar to that of first
molar except few differences:

+ Pulp chamber is smaller in size.

> One, two or more canals may be present.

> Mesiobuccal and mesiolingual canal orifices are usually located
closer together.

> When three canals are present, shape of access cavity is almost
Similar to mandibular first molar, but it is more triangular and less
of rhomboid shape.

> When two canal orifices are present, access cavity is rectangular
wide mesiodistally and narrow buccolingually.

= Average length= 20mm.
= Mesial root have 2 canals, while distal root have one canal.

35. Ly

Mandibular second molar.

ime of crupscn, 1

98 mm. Rox enmon to leas commun) mex

36. + Studies of apical canal configurations of mandibular second molar

Two Three
Author(s) Type of Study Country Root One Canal (%)* Canals (%)' Canals (%) Other (%)
Vertucei?'® Clearing USA Mesial 65 (38) 35 (9) = =
Pineda and Kuttler'* Radiographic Mexico Mesial 78.6 (21) 21.4 (8) — =
Caliskan et al” Clearing Turkey Mesial 41.2 (19) 56.9 2 =
Weine et al” Radiographic USA Mesial 56 (52) 40 = 1.3 (one canal);
with file 2.7(C
shaped)'?

Manning"? Clearing Australia Mesial 73.5 (32) 24.5 (10) 2 =
Wells and Bernier? Clinical USA Mesial Case report _ _ =
Beatty and Krell” Clinical USA Mesial — _ Case report —
Pomeranz et al'® Clinical USA Mesial — 26(3—2 26 =
Sert and Bayirli'* Clearing (men) Turkey Mesial 70 (56) 30 (7) =

Clearing (women) Turkey Mesial 61 (50) 39 (6) =
Vertucei?'® Clearing USA Distal 95 (3) 4) =
Pineda and Kuttler'” Radiographic Mexico Distal 96.5 (2) 3.5 (0.5) =
Caliskan et al? Clearing Turkey Distal 96.1 (14) 3.9 =
Weine et al”? Radiographic USA Distal 94.6 (9) 13 1.3 (one

with file canal); 2.7
C shaped
Manning"? Clearing Australia Distal 98.3 an =
Beatty and Krell” Clinical USA Distal — Case report —
Wells and Bernier Clinical USA Distal Case reportiM — —
and D join)

Sert and Bayirli'* Clearing (men) Turkey Distal 96(18) 4 (2) =

Clearing (women) Turkey Distal 93 (19) 7 (5) _

40. ls in the distal root.

et al reported that mandibular
occasionally have an
distolingual root (radix
RE). The occurrence of
rooted mandibular first
than (3-5%).

41. The main cause for C-shaped roots and canals is the failure of Hertwig’s
epithelial root sheath to fuse on either the buccal or lingual root surface;

The most C-shaped canals occur in the mandibular second molar, they
have also been reported in the mandibular first molar, the maxillary
first and second molars and the mandibular first premolar.

These can be classified into:
1. Category I (C1): The shape is an uninterrupted “C” with no separation
or division.
2. Category II (C2): The canal shape resembles a semicolon resultpty
from a discontinuation of the “C” outline.

42. 3. Category III (C3): Two or three separate canals.

4. Category IV (C4): Only one round or oval canal is in the cross-section.

5. Category V (C5): No canal lumen can be observed (is usually seen near
the apex only).

= Extirpation of pulp may be difficult leading to more bleeding which <a@
be mistaken for perforation. Removal of pulp tissue at coronal istumus
is difficult. To overcome these difficulties, the dental operating
microscope, sonic and ultrasonic instrumentation and thermoplastic
obturation techniques should be used.

44. If possible, complete removal of extensive restoration allows the most
favorable access to the root canals.

If the restorations show no defect, leaky margins, fractures or caries, access
can be made through them. For cutting porcelain restorations diamond
burs are effective and for cutting through metal crowns, a fine cross-cut
tungsten carbide bur is very effective.

When restoration is not removed, and access cavity
is made through it, following can occur:
= Coronal leakage because of loosening of fillings
due to vibrations while access preparation.
> Poor visibility and accessibility.
> Blockage of canal, because broken filling pieces
may struck into the canal system.
> Misdirection of bur penetration (because in
some cases restorations are placed to change
the crown to root angulations so as to correct
occlusal discrepancies).

45. If tooth is severely tilted, access cavity should be prepared with great
care to avoid perforations. Preoperative radiographs are of great help im
evaluating the relationship of crown to the root. Sometimes it becomes
mecessary to open up the pulp chamber without applying the rubber
dam so that bur can be placed at the correct angulation.

If not taken care, the access cavity
preparation in tilted crowns can result
in:

** Failure to locate canals.

** Gouging of the tooth structure.

** Procedural accidents such as:

instrument separation,
perforation. >

e Improper debridement Of pulp! so: 15.54 aná & ro avoid perforations, the direction of access
space. Proper angulation of bur according to ted crow (5) Perforation if

bur is misdirected

46. Calcifications in the pulp space are of common occurrence. Pulp space
can be partially or completely obliterated by the pulp stones. Teeth with
calcifications result in difficulty in locating and further treatment of the
calcified canals.

Special tips for ultrasonic handpieces are best suited for treating such
cases. They allow the precised removal of dentin from the pulp floor
while locating calcified canals. But magnification and illumination are
the main requirements before negotiating a calcified canal.

If Special tips are not available then a
pointed ultrasonic scaler tip can be used for
removal of calcifications from the pulp
space. One should avoid over cutting of the
dentin in order to locate the canals, this will
further result in loss of landmarks and the £

tooth weakening. aca ee a

47. Sometimes sclerosed canals are found in teeth which make the
endodontic treatment a challenge. For visualization, magnification and
illumination are the main requirements.

Dyes can be used to locate the sclerotic canals. While negotiating, the
precised amount of dentin should be removed with the helpyor
Ultrasonic tips to avoid over cutting.

ong shanked low speed No. 2 round burs can also be used. Use or
chelating agents in these cases is not of much help because it softens thy
dentin indiscriminately, resulting in procedural errors sucha
perforations. =

Fig. 15.50 Us

48. Some precautions are needed while dealing with such cases:
Y” Evaluate the preoperative radiograph to assess the root angulation.
¥ Start the cavity preparation without applying rubber dam.
¥ Evaluate the depth of penetration from preoperative radiograph.
Y Apply rubber dam as soon as the canals have been located.

if precautions are not taken in case of missing crown, there are Chances)or
Occurrence of iatrogenic errors like perforations due to misdirection of the buy
In such cases, sometimes it becomes imperative to rebuild the tooth previous to
endodontic treatment. In teeth with weakened walls, it is necessary to reinforee
the walls before initiating endodontic treatment. In other words, it is necessary
to restore the natural form of a crown of the tooth to achieve following goals;

Y Return the tooth to its normal form and
function.

Y Prevent coronal leakage during treatment.

Y” Allow use of rubber dam clamps.

y” Prevent fracture of walls which can complicate
the endodontic procedure.

49. Y Advanced endodontics 1st ed. 2009.

¥ Endodontics (Principles & Practice) Torabinejad 4th ed. 2009;
M Endodontics- Castellucci 12th ed. 2009.

¥ Endodontics- Ingle 6th ed. 2008.

¥ Pathways of the pulp 10th ed. 2011.

¥ PDO endodontics 1st ed. 2009.

¥ Textbook of endodontics- Nisha Garg 3rd ed. 2014.