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Table of Contents   
ORIGINAL RESEARCH  
Year : 2011  |  Volume : 22  |  Issue : 2  |  Page : 219-224
A comparative evaluation of film and digital panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars


Department of Oral Medicine and Radiology, J S S Dental College and Hospital, Mysore, India

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Date of Submission04-Mar-2010
Date of Decision07-Aug-2010
Date of Acceptance19-Aug-2010
Date of Web Publication27-Aug-2011
 

   Abstract 

Background and Objective: Digital photo stimulable phosphor (PSP)-based radiography has many known theoretical advantages over conventional film radiography but its diagnostic efficacy has to be assessed clinically. This study compared the efficiency of conventional film-based panoramic radiographs with that of digital PSP-based panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars.
Materials and Methods: We selected a total of 80 impacted mandibular third molars that fulfilled the inclusion and exclusion criteria of this study. Both conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs were taken of all the study samples and the teeth were later surgically removed. Conventional film-based and digital PSP-based panoramic radiographs were compared for their relative efficiencies in the assessment of impaction status, position of tooth, number of roots, root morphology, and proximity to mandibular canal of impacted mandibular third molars. An oral surgeon graded these same factors during/after surgical exploration and this assessment was considered the gold standard. The data obtained were statistically analyzed using descriptive statistics, chi-square test, and McNemar's test.
Results: There was no statistically significant difference between conventional film-based radiographic assessment and digital PSP-based panoramic radiographic assessment of impaction status, position of tooth, number of roots, and proximity to mandibular canal of impacted mandibular third molars (P>0.05). However, there was significant difference between the two methods with regard to assessment of root morphology of impacted mandibular third molars (P=0.00).
Interpretation and Conclusion : Conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs were comparable in their accuracy in the preoperative study of impacted mandibular third molar with regard to impaction status, tooth position, number of roots, and proximity to the mandibular canal. Digital PSP-based panoramic radiographs were more accurate than conventional film-based panoramic radiographs in the assessment of root morphology of impacted mandibular third molars. Hence, we conclude that digital PSP-based panoramic radiographs can be used as an effective alternative to conventional film-based panoramic radiographs for assessment of position and morphology of impacted mandibular third molars.

Keywords: Conventional film radiographs, digital PSP radiographs, mandibular third molars, impaction

How to cite this article:
Mahesh M S, Mahima V G, Patil K. A comparative evaluation of film and digital panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars. Indian J Dent Res 2011;22:219-24

How to cite this URL:
Mahesh M S, Mahima V G, Patil K. A comparative evaluation of film and digital panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars. Indian J Dent Res [serial online] 2011 [cited 2014 Nov 22];22:219-24. Available from: http://www.ijdr.in/text.asp?2011/22/2/219/84290
With the advent of film-less digital radiography, medical diagnostics has enhanced by leaps and bounds. Conventional film radiography, however, continues to be an integral part of diagnostic radiology. The diagnostic capabilities of the techniques, one time-tested and the other recently introduced and claiming several advantages, need to be assessed in the clinical setup.

Mandibular third molar impactions are common complaints seen in the dental office. Prompt removal after a meticulous preoperative assessment is important to prevent untoward complications related to their presence or during their surgical removal. The panoramic radiograph gives an essential information related to the jaws and its surrounding and supporting structures on one film. They are used as basic screening films in routine dental practice for diagnosing anomalies of the dentition and the jaws.


   Materials and Methods Top


The present study was conducted to ascertain which of the two - conventional film radiography or digital PSP-based panoramic radiography - is the better imaging tool in the study of impacted mandibular third molars.

Institutional ethical committee clearance was obtained prior to the start of the study. The study subjects were briefed about the study and written consent was obtained from each subject for inclusion in the study. The general particulars of the selected patients were noted and recorded on a specially designed proforma.

The study group consisted of 51 patients, both males and females, in the age group of 20-40 years, with unilateral or bilateral impacted mandibular third molars. Among the 51 patients, 29 presented with bilateral impacted mandibular third molars and 22 had unilateral impacted mandibular third molars, together constituting 80 study samples, i.e., there were a total of 80 impacted mandibular third molars included in the study [Table 1].
Table 1: Distribution of impacted mandibular third molars according to age and gender


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Patients with any of the following features were not included in the study:

  • Any gross anomaly associated with the impacted mandibular third molar or the adjacent facial bony structures
  • Any previous history of surgical procedures pertaining to the posterior mandible
  • Dental caries of the impacted mandibular third molars Radiographs/images with poor diagnostic quality


The selected patients were clinically examined and were subjected to radiographic examination. Initially, a conventional film-based panoramic radiograph was made, followed by a digital PSP-based panoramic radiograph. The exposed radiographs were labeled and stored until they were interpreted. After the radiographs were made, the study subjects underwent surgical removal of their impacted mandibular third molars during which the oral surgeon graded the study samples according to the assessing criteria devised for the study 9 described below); this was considered as the gold standard.

The film panoramic radiographs were made using T-mat G film (Eastman Kodak, Rochester, NY) housed in a cassette with intensifying screens (Kodak Lanex Regular) and exposed with a dental panoramic unit (Orthoslice 1000 C, Trophy, France) in auto-exposure mode with a magnification of 1.23. The exposed panoramic films were processed in a fully-automatic processor (Promax 5-speed, Chayagraphics, India) set at standard time and temperature throughout the study. All film radiographs were subjected to routine quality control. Radiographs with exposure and/or position errors were rejected and retaken.

The digital PSP-based panoramic radiographs were made using a PSP imaging plate (Digident, Orex CR technologies, Nesher, Israel) loaded in a cassette without intensifying screens (Kodak Lanex flat cassette) and the exposure was made using the same dental panoramic unit. The exposure parameters used for PSP plates were identical to those used for the conventional films.

Immediately after exposure, the PSP plates were scanned in the scanner, (Combix-2000, Orex CR technologies, Nesher, Israel) using manufacturer's default settings. The digital panoramic images were subjected to routine quality control and any images with errors were repeated. Images were labeled and stored in BMP format.

The third molar under investigation was assessed for the following criteria (grading done by the oral surgeon was according to the scores indicated)

Impaction state

  • Fully impacted in bone - 1
  • Semi impacted in bone - 2


Tooth position

  • Vertical - 1
  • Mesioangular - 2
  • Distoangular - 3
  • Horizontal - 4


Number of roots

  • Single - 1
  • Double - 2
  • Multiple (more than two) - 3


Root morphology

  • Straight (all roots) - 1
  • Curved (all roots) - 2
  • Mixed (at least one straight combined with one curved) - 3


Proximity to the mandibular canal

  • Not close - 0
  • Close - 1


The findings on the conventional film-based radiographs and digital PSP-based radiographs were entered in the respective proformas specially designed for the study.

Impaction state was assessed visually and by probing after soft tissue incisions and reflections. Tooth position was assessed visually after soft tissue reflection and bone removal. The number of roots and root morphology were assessed visually after removal of the tooth.

Proximity to the mandibular canal was assessed visually in relation to two parameters:

  • Inferior alveolar nerve visible after removal of the tooth
  • Indentations on the roots visible after removal


If one or both of the above were present, the tooth was defined as being close to the mandibular canal. The findings were recorded in the specially designed proformas. The recordings at/after the surgerywere the gold standard against which the radiographic findings were compared.

The conventional film panoramic radiographs were evaluated on a LCD view box and the digital PSP-based panoramic radiographs were viewed on a 15-inch PC monitor after enhancement of the images.


   Results Top


The data obtained were tabulated and subjected to statistical analysis using McNemar's test, contingency coefficient test, chi-square test, and descriptive statistics. We used SPSS for Windows for statistical analysis.

We found that assessment pertaining to impaction status, tooth position, number of roots, and proximity to the mandibular canal by conventional film-based panoramic radiography and by digital PSP-based panoramic radiography were not significantly different (P>0.05) [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10] and [Table 11]. However, with regard to assessment of root morphology, there was a statistically significant difference between conventional film-based radiography and digital PSP-based radiography (P=0.00) [Table 8] and [Table 9].
Table 2: Cross-tabulations of impaction status of mandibular third molars among conventional film-based, digital PSP-based panoramic radiographs and surgeon's grading


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Table 3: Chi-square tests of impaction status of mandibular third molars among conventional film-based and digital PSP-based panoramic radiographs


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Table 4: Cross tabulations of tooth position of impacted mandibular third molars among conventional film-based, digital PSP-based panoramic radiographs and surgeon's grading


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Table 5: Chi-square tests of tooth position of impacted mandibular third molars among conventional film-based and digital PSP-based panoramic radiographs


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Table 6: Cross tabulations of number of roots of impacted mandibular third molars among conventional film-based, digital PSP-based panoramic radiographs and surgeon's grading


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Table 7: Chi-square tests of number of roots of impacted mandibular third molars among conventional film-based and digital PSP-based panoramic radiographs


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Table 8: Cross tabulations of root morphology of impacted mandibular third molars among conventional film-based, digital PSP-based panoramic radiographs and surgeon's grading


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Table 9: Chi-square tests of root morphology of impacted mandibular third molars among conventional film-based and digital PSP-based panoramic radiographs


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Table 10: Cross tabulations of proximity to mandibular canal of impacted mandibular third molars among conventional film-based, digital PSP-based panoramic radiographs and surgeon's grading


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Table 11: Chi-square tests of proximity to mandibular canal of impacted mandibular third molars among conventional film-based and digital PSP-based panoramic radiographs


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   Discussion Top


In the present study, among the 80 study samples (impacted mandibular third molars), 38 (47.5%) were on the right side and 42 (52.5%) were on the left side. Forty-one (51.2%) of the impacted molars were in males and thirty-nine (48.8%) in females.

Impaction status

There was no significant difference between conventional film-based radiography and digital PSP-based panoramic radiography in accuracy of assessment of impaction status.

Compared to the gold standard, conventional film-based panoramic radiographs overestimated the status of fully impacted mandibular third molars and underestimated the status of semi-impacted mandibular third molars. On the other hand, digital PSP-based panoramic radiographs overestimated the status of fully impacted mandibular third molars and underestimated the status of semi-impacted mandibular third molars. The differences however were not statistically significant and it can be inferred that conventional film-based panoramic radiographs and digital PSP-based panoramic radiographs are equally precise in determining the impaction status of mandibular third molars.

Tooth position

There was no major difference between conventional film-based and digital PSP-based panoramic radiography in accuracy in assessing the position of the impacted tooth.

When assessing the tooth position, conventional film-based panoramic radiographs overestimated the number of vertical, distoangular, and horizontally impacted mandibular third molars when compared to the gold standard. On the other hand, they under estimated the number of mesioangularly impacted mandibular third molars.

The digital PSP-based panoramic radiographs accurately assessed the number of vertical, mesioangular, distoangular, and horizontally impacted mandibular third molars when compared to the gold standard. Although digital

PSP-based panoramic radiographs scored over the conventional film-based panoramic radiographs in assessing the tooth position, the differences were not statistically significant and it can be concluded that conventional film-based panoramic radiographs and digital PSP- based panoramic radiographs are equally accurate in determining the position of impacted mandibular third molars.

Number of roots

There was no conspicuous difference between conventional film-based and digital PSP-based panoramic radiographs as far as assessment of the number of roots was concerned.

Conventional film-based panoramic radiography was accurate in assessment in teeth with double roots. However, it underestimated the single-rooted and overestimated multiple-rooted impacted mandibular third molars. Digital PSP-based panoramic radiographs on the other hand accurately assessed single-, double-, and multiple-rooted impacted mandibular third molars.

Thus, digital PSP-based panoramic radiographs scored over conventional film-based panoramic radiographs in assessing the number of roots. Again, these minor differences were not statistically significant, and we can infer that for all practical purposes the two methods are equally accurate in determining the number of roots in impacted mandibular third molars.

Root morphology

With regard to assessment of root morphology of impacted mandibular third molars, conventional film-based radiography and digital PSP-based panoramic radiography showed significant difference. Conventional film-based panoramic radiographs heavily underestimated the presence of straight roots and overestimated the presence of curved and mixed roots. Digital PSP-based panoramic radiographs, on the other hand, over estimated the number of impacted mandibular third molars with straight rootsand curved roots when compared to the gold standard but under-estimated the number of impacted mandibular third molars with mixed roots in.

Statistically, a significant difference existed (P=0.00). Thus, it can be inferred that digital PSP-based panoramic radiographs are more accurate than conventional film-based panoramic radiographs for determining the root morphology of impacted mandibular third molars.

Proximity to the mandibular canal

There was no major difference between conventional film-based radiography and digital PSP-based panoramic radiography with regard to assessment of proximity of impacted mandibular third molars to the mandibular canal.

Conventional film-based panoramic radiographs under-estimated the number of the impacted mandibular third molars which were not close to the mandibular canal and over estimated the number of impacted mandibular third molars which were close to the mandibular canal when compared with the gold standard. Conversely, digital PSP-based panoramic radiographs over estimated the number of impacted mandibular third molars which were not close to the mandibular canal and under-estimated the number of impacted mandibular third molars which were close to the mandibular canal.

Statistically, however, these minor differences were not significant and it can be inferred that both methods are equally precise in determining the proximity to the mandibular canal of impacted mandibular third molars.

Our findings pertaining to assessment of the impaction status, tooth position, number of roots, and proximity to the mandibular canal of impacted mandibular third molars by conventional film-based radiographs and digital PSP-based panoramic radiographs are consistent with those from an earlier study by Benediktsdottir and Hintze et al., [1] which reported no statistically significant difference between the two modalities. However, with regard to assessment of root morphology, the results of the present study contradicts the findings of Benediktsdottir and Hintze et al., [1] who reported that there was no statistically significant difference between conventional film-based and digital PSP-based panoramic radiographs in assessing the root morphology of impacted mandibular third molars, and that both conventional film-based and digital PSP-based panoramic radiographs are equally accurate for assessing root morphology.

It is well known that poor diagnostic quality of images due to magnification, geometric distortion, poor definition, and loss of detail is inherent to panoramic radiographs. The possibility that subtle curvature in the roots of the impacted mandibular third molars could have been missed by the investigator on the conventional film-based panoramic radiographs due to these reasons cannot be ruled out. On the other hand, the digital PSP images were enhanced before interpretation. The enhancement of the images may have contributed to the better diagnostic quality of PSP images as compared to conventional film radiographs. Studies conducted by Boascolo et al. [2] and Attaelmann et al. [3] have both established that enhanced digital images have higher diagnostic quality than unenhanced images.

Kashima et al., [4] Moystad et al., [5] Kuhnisch et al., [6] Cederberg et al., [7] Borg et al., [8] Holtzmann et al., [9] and Syriopoulos et al. [10] have all found that digital PSP-based radiographs are either equally accurate or superior to conventional film-based radiographs in oral radiodiagnosis and the present study is in agreement with them.

The present study did not consider intraobserver variations, which are bound to cause differences in visual determination. The effects of receptor dosage, image size, and computer-aided diagnosis on the accuracy of digital PSP-based images were also not considered.

Further research that takes into consideration the above mentioned parameters and involves a larger sample size may shed more light on the accuracy of conventional film-based and digital PSP-based panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars.


   Conclusion Top


From the present study, it was observed that both conventional film-based panoramic radiography and digital PSP-based panoramic radiography were comparable in their accuracy in the preoperative assessment of impaction status, tooth position, number of roots, and proximity to the mandibular canal of impacted mandibular third molars.

Digital PSP-based panoramic radiographs possess several advantages and hence can be used as an effective alternative to the conventional film-based panoramic radiographs in the assessment of position and morphology of impacted mandibular third molars.

 
   References Top

1.Benediktsdottir IS, Hintze H, Petersen JK, Wenzel A. Accuracy of digital and film panoramic radiographs for assessment of position and morphology of mandibular third molars and prevalence of dental anomalies and pathologies. Dento Maxillofac Radiol 2003;32:109-15.  Back to cited text no. 1
    
2.Boscolo FN, Oliveira AE, Almeida SM, Haiter CF, Neto FH. Clinical study of the sensitivity and dynamic range of three digital systems, E-speed film and Digitized film. Braz Dent J 2001;12:191-5.   Back to cited text no. 2
    
3.Attaelmanan A, Borg E, Grondahl HG. Digitization and display of intra-oral films. Dento Maxillofac Radiol 2000;29:97-102.  Back to cited text no. 3
    
4.Kashima I, Kanno M, Higashi T, Takano M. Computed panoramic tomography with scanning laser-stimulated luminescence. Oral Surg Oral Med Oral Pathol 1985;60:448-53.  Back to cited text no. 4
[PUBMED]    
5.Moystad A, Svanaes DB, Risnes S, Larheim TA, Grondahl HG. Detection of approximal caries with a storage Phosphor system. A comparison of enhanced digital images with dental x ray film. Dento Maxillofac Radiol 1996;25:202-6.  Back to cited text no. 5
    
6.Kuhnisch J, Ifland S, Tranaeus S, Weltzien RH. Comparison of visual inspection and different radiographic methods for dentin caries detection on occlusal surfaces. Dento Maxillofac Radiol 2009;38:452-7.  Back to cited text no. 6
    
7.Cederberg RA, Tidwell E, Frederiksen NL, Benson BW. Endodontic working length assessment, comparison of storage phosphor digital imaging and radiographic film. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:325-8.  Back to cited text no. 7
[PUBMED]  [FULLTEXT]  
8.Borg E, Grondahl HG. Endodontic measurements in digital radiographs acquired by a photostimulable storage phosphor system. Endod Dent Traumatol 1996;12:20-4.  Back to cited text no. 8
    
9.Holtzmann DJ, Johnson WT, Southard TE, Khademi JA, Chang PJ, Rivera EM. Storage-phosphor computed radiography versus film radiography in the detection of pathologic periradicular bone loss in cadavers. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;86:90-7.  Back to cited text no. 9
    
10.Syriopoulos K, Sanderink GC, Velders XL, van der Stelt PF. Radiographic detection of approximal caries: a comparison of dental films and digital imaging systems. Dento Maxillofac Radiol 2000;29:312-8.  Back to cited text no. 10
    

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Correspondence Address:
Karthikeya Patil
Department of Oral Medicine and Radiology, J S S Dental College and Hospital, Mysore
India
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DOI: 10.4103/0970-9290.84290

PMID: 21891889

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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7], [Table 8], [Table 9], [Table 10], [Table 11]



 

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