Ex-Vivo Evaluation of X-Ray Horizontal Angle for Separating the Canals of Four-Canal First Mandibular Molars.

0.15 MB·English

by  Haghani, Jahangir

ORIGINALARTICLE
Ex-Vivo Evaluation of X-Ray Horizontal Angle for
Separating the Canals of Four-Canal First
Mandibular Molars
JahangirHaghani1,MaryamRaoof2*,SadeghPourahmadi3
1.DepartmentofOralRadiology,DentalSchool,KermanUniversityofMedicalsciences,Kerman,Iran
2.DepartmentofEndodontics,DentalSchool,KermanUniversityofMedicalsciences,Kerman,Iran
3.GeneralPractitioner,Kerman,Iran
ABSTRACT
INTRODUCTION:Avarietyofmesialanddistalprojectionshavebeensuggestedforseparating
the canals in a multi-canaled root. But there is no general agreement on the best angulation for
each tooth. The purpose of this study was to evaluate the X-ray horizontal angle for separating
thecanalsoffour-canalfirstmandibularmolars.
MATERIALS AND METHODS: Forty four-canaled mandibular molars were selected. After
preparationofcoronalaccesscavities,fileswereinsertedintotherootcanalsandthespecimens
wereradiographedat10,15,20,25degreesmesialanddistalhorizontalangulations.Apicesand
canalswereevaluated.Chi-squaretestwasusedforstatisticalanalysis.
RESULTS: Although 10° and 15° mesial and distal angulations were best for the most obvious
apices manifestation (P<0.001), it was found that 20° mesial angulation is significantly better
thantheotherconeangulations(P<0.001)forseparatingtherootcanals.
CONCLUSION:20°mesialangulationimproveddetectionofboththecanalsandcanalterminus
visibility.
Keywords:Endodontics;Molar;Radiology;RootCanal
Received:26Feb2007;Revised:15Jul2007;Accepted:17Sep2007
*Correspondingauthorat:MaryamRaoof,DepartmentofEndodontic,KermanDentalSchool,ShafaAve,Jomhuri
EslamiBlvd,Kerman,Iran.E-mail:[email protected]
INTRODUCTION However, as the horizontal angulation
increases, the clarity of the radicular anatomy
A key objective of successful nonsurgical decreases (5). So having a clear image of the
endodontic treatment is effective chemo- apex and therefore the WL determination
mechanical debridement of the root canal wouldbemoredifficult.
systems(1).Onefactorinachievingthisgoalis A variety of mesial and distal projections have
establishment of precise working length (WL) been suggested for effective “opening-up” the
(2). canals (5-7). But, there is no general agreement
Different techniques have been used for onthe bestangulationforeachtooth.Therefore
determining WL including: radiography, sometimes we need to obtain several
electronic devices, using paper point, tactile radiographs that involve different cone angles
methods and patient reaction. None are totally with respect to the target tooth to have an
accurate, so all the techniques must be used acceptable image of all canals (8). This can
onlyasanadjuncttoradiography(2). result in economic and also biologic side
Conventional intraoral radiography using silver effects.
halidefilmisawidelyusedandreliableclinical The prevalence of four canals especially in
methodofdeterminingWL(3). mandibular first molar is noticeable and varies
In a multi-canaled root the canals are in different studies (9-12). On the other hand,
superimposedoneupontheother.Usingspecial this is the earliest permanent posterior tooth to
cone angulations, these structures can be erupt and seems to be the tooth that most often
movedaparttosolvethisproblem(4). requires root canal treatment (13). So,
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Haghanietal.
Table 1. Frequencyand distributionofcanalsseparation Table 2. Frequencyanddistributionofcanalsseparation
inmesialconeangulations indistalconeangulations
Cone Separationoffourcanals(#40) Cone Separationoffourcanals(#40)
angulation Yes No angulation Yes No
(degree) Number Percent Number Percent (degree) Number Percent Number Percent
10 0 0 40 100 10 0 0 40 100
15 15 37.5 25 62.5 15 10 25 30 75
20 33 82.5 7 17.5 20 16 40 24 60
25 20 50 20 50 25 19 47.5 21 52.5
suggesting an appropriate radiographic cone designed and a rectangular cardboard was
angulation may be helpful to better performing installed on the radiographic tube head as a
rootcanaltherapy. marker,theseenabledprecisevariationsincone
The purpose of this ex-vivo study was to angulation.Thespecimenswereadjustedonthe
evaluate the effect of different x-ray tube scaled plate and the teeth were radiographed.
angulations on defining the apices and The samples and dental x-ray unit were
separationofnumerousrootcanals. positioned to obtain a 0.8 cm focal spot–object
distance. Conventional E–Speed intra-oral
MATERIALSANDMETHODS radiographic films (Kodak, Eastman Kodak,
NY, USA) were exposed at 10,15,20,25
Included in this study were mandibular recently degreesmesialanddistalhorizontalangulations
extracted molars with fully formed roots. The with the x-ray unit operating at 70 kvp, 8mA,
specimens with dilacerations, external root for 0.32 s (Planmeca intra X-ray unit, Finland).
resorptionandfracturehadtobeexcluded.Teeth Vertical angle was -5° for all the specimens.
were washed immediately after extraction and Films were developed in an automatic
stored in normal saline until the collection was processor (Velopxe, Extrax medien, UK) using
completed. Thereafter, the teeth were properly champion developer and fixer solutions
washedundertapwaterandimmersedin5.25% (champion photochemistry, Iran). A board-
sodium hypochlorite for 30 min for the removal certified radiologist compared the images
of organic debris on the surface. The specimens without magnification on a light viewing box
were radiographed from buccal view to assess (Shayanteb, Iran). He determined the apices
canalmorphologyandthoseidentifiedashaving and separation of the canals. No time limit was
abnormal anatomy or calcified root canal set for viewing and the observer was allowed a
systemswereexcluded. rest periodwhenever he felt fatigue.Chi-square
Coronal access opening were prepared using test was performed for the statistical analysis
tungsten carbide burs in a high speed usingSPSSversion15.
handpiece. The canals were located using an
endodontic explorer and 40 four-canal teeth RESULTS
were selected. The teeth immersed in 2.5%
sodium hypochlorite solution for 24 hours to Results presented in Table 1 and Table 2 show
dissolve any pulp tissue. Root canal working that the mesial 20° radiograph is significantly
length was set at 1 mm short of the apical better than the other cone angulations for
foramen based on visual inspectionof a size 10 separatingtherootcanals(P<0.001).Therewas
stainless steel K-file penetrating beyond the no separation when 10° mesial and distal
apicalforamen.Theteethwerethenmountedin angulations applied. The results concerning the
self–cure acryl boxes. The teeth aspects were apices defining with regard to different mesial
marked as M: mesial, B: buccal, D: distal and and distal cone angulations are shown in Table
L: lingual. Canals were then prepared ( if 3, and Table 4, respectively. An increase in
necessary) by hand until a size 20 K-file horizontal angle was found to be related to
(Maillefer, Dentsply, Swiss) bound at the decrease of defining ability of the apices.
working length. Files were inserted passively Specifically, the angulations of 10° and 15°
into the root canals. A horizontal goniometer mesial and distal were best for the most
which was able to show every5degreeswas obviousapicesmanifestation(P<0.001).
144 IEJ
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Separatingtherootcanals
Table 3. Frequency and distribution of radiographic Table 4. Frequency and distribution of radiographic
apicesdefininginmesialconeangulations apicesdefiningindistalconeangulations
Cone Separationoffourcanals(#40) Cone Separationoffourcanals(#40)
angulation Yes No angulation Yes No
(degree) Number Percent Number Percent (degree) Number Percent Number Percent
10 40 100 0 0 10 40 100 0 0
15 40 100 0 0 15 40 100 0 0
20 36 90 4 10 20 32 80 8 20
25 11 27.5 29 27.5 25 6 15 34 85
DISCUSSION
another in vitro study, Naoum et al. stated that
The prevalence of four canals in mandibular conventionalradiographstakenata0°orientation
molars varies in different studies (8-11). The were significantly better than 30° images for
mesial root of the mandibular first molar detectingthenumberofvisiblecanals(7).
usually has two canals. The prevalence of two In all 10° mesial and distal images the canals
canals in the distal root ranges from 11.2% to were superimposed one upon the other and
43.3% (9-15). About the mandibular second appeared as a single line. Moreover, when 10°
molar,21.4%to56.9%ofthemesialrootshave or 15° mesial or distal radiographs were
beenshowntohavetwocanals(9,11,16,17). considered,it was obviousthat theapicescould
This range is about 1/3% to 4% in distal root be clearly visualized but the canals were not
(9,11,16,17). Therefore, the prevalence of four separated adequately. So, 20° mesial angulation
rootcanalsinmandibularmolarsisnoticeable. improvedbothdetectionofthecanalsandcanal
Careful assessment of pulp anatomy obtained terminusvisibility.
from a diagnostic radiograph is very important In the present study we attempted to follow
to eradicate intra-radicular infection. steps that could be applied in vivo. It was
Radiologic evaluation of the three dimensional difficult to achieve a precise horizontal angle.
configuration of the root and canal system is We solved this problem by designing a
recommended in endodontics (18). We goniometer. The limitations of this ex-vitro
preferred conventional radiographs rather than studyshould be taken into account andindicate
digital radiographs because the dentists are theneedforfurtherwork.
more familiar with the former and the
conventional radiography equipments are more CONCLUSION
available in many dental clinics. Moreover, the
image quality of the conventional radiographs According to this study, it looks like that using
hadbeenbetterthantheolderdigitalsystemsin 20° mesial angulation improves detection of
some studies (19-21). The dental x-ray films boththecanalsandapices.
used in this study (Kodak, E-speed, Eastman
Kodak,Ny,USA) were chosenbecause of their ACKNOWLEDGEMENT
routine use in dental clinics, while they have
alsohigherresolutionandbettercontrast(22). This study was Dr. S. Pourahmadi’s thesis and
It is more probable that an angled radiographic was supported by Kerman dental school,
view will reveal additional information about Kerman, Iran.The authors wishtothankDr.H.
the number of canals and apex visibility (23). Safizadeh and Dr. AA. Haghdoost for their
According to this study, images taken at 20° invaluablehelps.
mesial angulation were significantlybetter than
10°, 15° and 25° angulations for detecting the ConflictofInterest:‘Nonedeclared’.
number of canals. This finding was in conflict
REFERENCES
with Walton who has suggested the distal
projection for mandibular molars (5). Ingle
1. Peters OA, Laib A, Gohring TN, Barbakow F.
proposed 20° to 30° mesial shift to adequately
Changes in root canal geometry after preparation
reflect the morphologic characteristics of the assessed by high-resolusion computed tomography.
mandibular molar root canal systems (6). In JEndod.2001;27:1-6.
IEJ 145
-Volume2,Number4,Winter2008
Haghanietal.
2. Farman AG, Farman TT. A comparison of 18 Cohen S, Hargreaves KM, editors. Pathways of the
different x-ray detectors currently used in dentistry. pulp. 9th Edition. St. Louis: CV Mosby; 2006. p.
OralSurgOralMedOralPatholOralRadiolEndod. 140.
2005;99:485-9. 14.SperberGH,MoreauJL.Studyofthenumberof
3. NaoumHJ,ChandlerNP,LoveRM.Conventional roots and canals in Senegalese first permanent
versus storage phosphor-plate digital images to mandibularmolars.IntEndodJ.1998;31:117.
visualize the root canal system contrasted with a 15. Skidmore AE, Bjorndal AM. Root canal
radiopaquemedium.JEndod.2003;29:349-52. morphology of the human mandibular first molar.
4. Martinez-Lozano MA, Forner-Navarro L, OralSurgOralMedOralPatholOralRadiolEndod.
Sanchez-CortesJL. Analysisofradiologicfactorsin 1971;32:778.
determining premolar root canal systems. Oral Surg 16. Pineda F, Kuttler Y. Mesiodistal and
OralMedOralPatholEndod.1999;88:719-22. buccolingual roentgenographic investigation of
5. Walton RE. Endodontic radiography. In: Walton 7275 root canals. Oral Surg Oral Med Oral Pathol
RE, Torabinejad M, editors. principles and practice OralRadiolEndod.1972;33:101.
of endodontics. 3d Edition. Philadelphia: W.B. 17. Weine FS, Pasiewicz RA, Rice RT. Canal
SaundersCompany;2002.pp.140–48. configuration of the mandibular second molar using
6. Ingle JI, Walton RE, Malamed SF, et al. a clinically oriented in vitro method. J Endod.
Preparation for endodontic treatment. In: Ingle JI, 1988;14:207.
Bakland LK, editors. Endodontics. 5th Edition. 18. McDonald NJ, Hovland EJ. Surgical
Hmilton,London:BCDeckerInk;2002.p.362. endodontics.In:WaltonRE,TorabinejadM,editors.
7. Naoum HJ, Love RM, Chandler NP, Herbison P. principles and practice of endodontics. 2nd Edition.
Effect of X-ray beam angulation and intraradicular Philadelphia:WBSaunders;1996.p.410.
contrast medium on radiographic interpretation of 19. Ellingsen MA, Harrington GW, Hollender LG.
lower first molar root canal anatomy. Int Endod J. Radiovisiography versus conventional radiography
2003;36:12-19. for detection of small instruments in endodontic
8. Degrood ME, Cunningham CJ. Mandibular molar length determination. Part 1. In vitro evaluation. J
with5canals:reportofacase.JEndod.1997;23:60-2. Endod.1995;21:326-31.
9. Vertucci FJ. Root canal anatomy of the human 20. Lozano A, Forner L, Llena C. In vitro
permanent teeth. Oral Surg Oral Med Oral Pathol comparison of root-canal measurements with
OralRadiolEndod.1984;58:589-99. conventional and digital radiology. Int Endod J.
10. Wasti F, Shearer AC, Wilson NH. Root canal 2002;35:542-50.
systems of the mandibular and maxillary first 21. Ellingsen MA, Hollender LG, Harrington GW.
permanent molar teeth of South Asian Pakistanis. Radiovisiography versus conventional radiography
IntEndodJ.2001;34:263. for detection of small instruments in endodontic
11. Caliskan MK, Pehlivan Y, Sepetcioglu F, length determination. II. In vivo evaluation. J
Turkun M, Tuncer SS. Root canal morphology of Endod.1995;21:516-20.
human permanent teeth in a Turkish population. J 22.LudlowJB,PlatinE.Densitometriccomparisons
Endod.1995;21:200. of ultra speed Ekta-speed and Ekta-speed plus
12.GulabivalaK,AungTH,AlaviA,MgY-L.Root intraoral films for two processing conditions. Oral
and canal morphology of Burmese mandibular SurgOralMedOralPathol.1995;79:105-13.
molars.IntEndodJ.2001;34:359. 23. Gulabivala K, Aung TH, Alavi A. Root and
13. Vertucci FJ, Haddix JE, Britto LR. Tooth canal morphology of Burmese mandibular molars.
morphology and access cavity preparation. In: IntEndodJ.2001;34:359-70.
146 IEJ
-Volume2,Number4,Winter2008