comparison of re-exposure rates of intraoral radiographs between dental students and trained dental...

7/29/2019 Comparison of Re-exposure Rates of Intraoral Radiographs Between Dental Students and Trained Dental Assistant

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RESEARCH

Comparison of re-exposure rates of intraoral radiographs

between dental students and trained dental assistants in an oral

and maxillofacial radiology clinic

M Mupparapu*,1, S Jariwala1, SR Singer1, IH Kim1 and M Janal2

1Department of Diagnostic Sciences, UMDNJ New Jersey Dental School, Newark, NJ 07101-1709, USA; 2Department of Psychiatry,UMDNJNew Jersey Medical School, Newark, USA

Objective: To compare the re-exposure rates of dental radiographs taken over a period of 1 yearbetween dental students and trained dental assistants at a university-based oral and maxillofacialradiology clinic.Methods: Detailed records of the number and type of intraoral radiographs taken by the studentsand staff members and the number of re-exposures that were required from July 2003 to July 2004were used. Statistical analyses were performed on the data.Results: A x2 test showed that re-exposure rates of radiographic series between students and staffwere statistically different. When comparing the students re-exposure rates during each of the fourquarters of their radiology rotation, one-way analysis of variance test showed that the results werenot statistically significant for reduction in the number of re-exposures over the entire year.Conclusions: There were significant differences in the re-exposure rates between staff dentalassistants and students. Film re-exposure rates for the students during the four quarters wereexpected to decrease with time. Instead, the consistency of the re-exposure rates of the studentsduring the four quarters demonstrates the need to recognize why the students did not perform betteras the year progressed. The percentage of films that needed to be re-exposed by either group(students or the staff dental assistants) was not extremely high.Dentomaxillofacial Radiology (2007) 36, 224228. doi: 10.1259/dmfr/91136616

Keywords: re-exposure rate, radiographs, rectangular collimator, dental student, dental assistant

Introduction

It has generally been observed that radiology staff dentalassistants have lower re-exposure rates than the third yeardental students, and it is assumed that the third year dentalstudents reach the level of expertise of staff dentalassistants after a yearlong radiology clinic rotation.Nixon and colleagues1 from the United Kingdom audited

film reject rates in a dental radiology department and foundan overall dental radiographic film reject rate of 3.06% intheir facility. The authors commented that there was asignificant difference in the reject rates between qualifiedstaff and those in training. These findings could not beconfirmed as no other studies were found in the literaturethat recorded the re-exposure rates and compared the

performance of dental students and staff dental assistantsover time.

It is known from the literature that, although dentalstudents had problems in identification of film faultsinitially, they had the fund of knowledge and competencein the assessment and correction of faults once identified.2

However, there is limited literature on this topic as well.This crucial information is valuable for the efficientclinical training of dental students. In addition, thisinformation can assist dental educators to understand thequality control issues and limitations within the oral andmaxillofacial radiology (OMFR) clinic.

The objective of this study was to compare the re-exposure rates of intraoral radiographs between the dentalstudents attending the radiology clinical rotation (OMFRclinic) and the staff dental assistants over a period of 1 year.This study was also intended to observe performancetrends among the dental students intraoral radiographic

*Correspondence to: Dr Muralidhar Mupparapu, DMD, MDS, Diagnostic Sciences,

D-860, UMDNJNew Jersey Dental School, 110 Bergen Street, Newark, NJ 07101-

1709, USA; E-mail: [email protected]

Received 21 September 2005; revised 10 April 2006; accepted 23 May 2006

Dentomaxillofacial Radiology (2007) 36,Dentomaxillofacial Radiology (2007) 36, 224228q 2007 The British Institute of Radiology

http://dmfr.birjournals.o rg


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technique utilizing rectangular collimation while attendingthe clinical rotation during this 1-year period. It isanticipated that the data obtained from this study will beuseful for the implementation of future clinical trainingprotocols for dental students.

Materials and methods

Radiology clinical training for junior (third) year dentalstudents begins with a mandatory 12 h training sessiontowards the end of the sophomore (second) year. Dentalradiograph teaching and training replicas (DXTTR; RINNCorporation, Elgin, IL) are used for the training before thestudents attend the clinical rotation in radiology. Dentalstudents rotate through the radiology clinic once every 4weeks in their junior year at the New Jersey Dental School.Junior year students normally spend both morning andafternoon sessions in radiology patient care. After obtain-ing a thorough medical and dental history and completionof a clinical examination, students are trained to indepen-dently perform the radiographic examinations. Staff dentalassistants in the clinic have had at least 10 years of

experience in clinical radiography after their initial

training and license. All radiographic studies were

performed using a long cone, rectangular collimator

using intraoral positioning devices (RINN XCP instru-

ments, DENTSPLY/RINN Corporation). A Kodak

Insightw film (speed group F; Eastman Kodak, Rochester,

NY) was used with the X-ray machine operating at 70 kV

and 15 mA, and processed in automatic processors (Dent-

X 9000; Dent-X Corp., Elmsford, NY). Calibrated OMFR

faculty used standard technique error assessment forms for

student teaching (Figure 1) to help identify the radiographs

that were inadequate for interpretation and subsequently

recommended re-exposures when necessary.

The radiographs were mounted on standard RINN mounts

(RINN Corporation) and viewed on a fluorescent light box

(Star X-Ray Inc., Amityville, NY) in a dimly lit room after

masking all extraneous light with a specially designed

cardboard mask. Thisis a standardprocedure forradiographic

studies that are completed within the OMFR clinic. The

students were then graded on the number and type of

technique errors as well as interpretation using the standard

grading form. Faculty underwent calibration exercises

Figure 1 Radiographic technique evaluation form that is used for all intraoral radiographic series

Comparison of re-exposure ratesComparison of re-exposure ratesM Mupparapu et al 225

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quarterly using the same error assessment forms and gradesheets within the 24-month period prior to the study.

Two types of radiographic film series were used for thisstudy: full mouth radiographic series (FMS) and select filmseries (SFS). A FMS typically has 14 periapical (14 PA)and 4 bitewing radiographs (4 BW films) obtained using

size 2 intraoral films. SFS ranged anywhere from 10 filmsto 17 films with a combination of periapical and/orbitewing films. If the radiographs failed to record anddisplay the desired information, a re-exposure was made.The decision to re-expose was made by the OMFR facultybased on following criteria:

(1) missing apices of teeth due to film positioning orvertical angulation error;

(2) missing contact points due to film positioning error;(3) overlap of contact points due to horizontal angulation

error;(4) collimator cut through the area of interest;(5) missing distal of the canines and canine-premolar

contacts in premolar bitewings;(6) any exposure error that makes the films less than ideal

to view;(7) any processing error that makes the films unaccep-

table;(8) blurred images due to patient movement; and(9) ifthe desiredarea of anatomy was not at all recorded in

any other views within the series.

A dailylog was kept by the OMFR clinic in which studentsand staff members were asked to record their status, thenumber of radiographs exposed and the number of re-exposures required at the endof eachstudy.Radiology facultyscreened all the radiographic series, adhering to the criteria as

outlined previously. Patient and student data from 25 July2003 to 26 July 2004 were used for this study. The data werecompiled and summarised intoa table by typeof examination,number of radiographs obtained, number of re-exposuresrequired for the type of error and status of the operator. Thisstudy complied with federally mandated Health InsurancePortability and Accountability Act regulations to protect theconfidentiality of patient data. An approval from theInstitutional Review Board was obtained.

Data analysisDifferences between the students and staff dental assistantsin the average re-exposure rates were assessed withindependent sample t-tests, while the differences in the

probability of at least one re-exposure were assessed withthe x2 statistic. Comparisons over time within the studentgroup employed one-way analysis of variance (ANOVA).

Results

Out of 20 158 radiographs obtained in the OMFR clinic bythe junior year dental students, 998 films were re-exposeddue to faulty technique, resulting in a 4.9% film re-exposure rate for the students. Out of 14 154 films exposedin the clinic by the staff members, only 19 films had to be

re-exposed to achieve a diagnostically acceptable study,resulting in a 0.2% film re-exposure rate for the staffmembers (Table 1). Independent t-test samples revealedthat the third year dental students had a significantly higheraverage film re-exposure rate than staff dental assistants(P , 0.001).

Radiographic series included both the FMS and SFS.Out of 797 radiographic series, staff dental assistantsrequired at least one re-exposure in 19 cases and none inthe other 778. Thus, 97.6% of the radiographic series doneby the staff members did not require any re-exposures. Outof 1154 series completed by the students, there were 518(44.9%) instances in which at least one re-exposure wasrequired. Thus, only 55.1% of the radiographic seriescompleted by the students did not need any re-exposures(Table 1). x2 test (424 557 with 1 degree of freedom andthe two-tailed P value,0.0001) indicated that staff dentalassistants had a statistically significant lower re-exposurerate than the third year dental students.

Table 2 summarises the mean re-exposure rate for

students (at least one re-exposure per radiographic series)during the four quarters with an average re-exposure rate of45%. Table 3 summarises the mean overall total film re-exposure rate during the same 12-month period with anaverage re-exposure rate of 4.9%. ANOVA on the datafrom Tables 2 and 3 revealed that the rates between thequarters varied only between 3% and 6% during the fourperiods. The re-exposure rates did not vary significantly(Figure 2). The re-exposure rates for the third year studentsdid not show a consistent trend towards improvementduring their 1-year rotation in dental radiology.

Discussion

One of the guiding principles in teaching radiology todental students is as low as reasonably achievable(ALARA). Decisions on radiographic prescriptions andre-exposures are based on this principle. Radiographicprescriptions are based on sound selection criteria3,4 thatinclude patient complaint, a detailed medical history and athorough intra and extraoral examination. Althoughradiographic selection criteria should be followed uni-versally, a recent study demonstrated that a greaterpercentage of dental schools in the United States andCanada that used selective radiography in accordance withthe FDA guidelines in 1987, switched to routine radiogra-

phy by 2002 than schools that switched in the oppositedirection.5 The 20-year positive trend of using selectiveradiography for the dental school patient population atdental schools in the United States and Canada had

Table 1 Re-exposure rates for staff dental assistants and students

Group

Radiographicseries with nore-exposures

Radiographic serieswith at leastone re-exposure

Total numberof radiographicseries

Staff 778 (97.6%) 19 (2.4%) 797 (100%)Students 636 (55.1%) 518 (44.9%) 1154 (100%)Total 1414 (72.5%) 537 (27.5%) 1951 (100%)

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assessment and correction of faults once identified.2 Futurestudies similar to this may be directed towards identifi-

cation of the students that consistently perform inade-quately, resulting in an increase in the overall re-exposurerate for the class. Interventions aimed at these students maysignificantly improve the overall student performance in agiven time period. This study was intended to help dental

educators identify limitations of the clinical radiologytraining of dental students and the results may be helpful

for any curricular modifications that may be required.Further studies are warranted to achieve the ultimate goalof providing students with the optimal educationalexperience in dental radiology while minimizing radiationto the patient.

References

1. Nixon PP, Thorogood J, Holloway J, Smith NJ. An audit of film rejectand repeat rates in a department of dental radiology. Br J Radiol 1995;68: 13041307.

2. Rushton VE, Hirschmann PN, Bearn DR. The effectiveness ofundergraduate teaching of the identification of radiographic filmfaults. Dentomaxillofac Radiol 2005; 34: 337342.

3. ADA Council on Scientific Affairs, An update on radiographic

practices: information and recommendations. J Am Dent Assoc 2001;132: 234238.

4. ADA Council on Dental Benefits programs, US Department of Healthand Human Services, Food and Drug Administration. The selection of

patients for dental radiographic examinations. Available at: http://www.fda.gov.cdrh/radhlth/adaxray-1.pdf. Revised 2004. Accessed 10April 2006, pp. 127.

5. Kantor ML. Longitudinal trends in the use of individualized radio-graphic examinations at dental schools in the United States andCanada. J Dent Educ 2006; 70: 160168.

6. National Council on Radiation Protection and Measurements (NCRP).Radiation protection in dentistry. NCRP Report No. 145, Bethesda,MD: NCRP; 2003, pp. 1439.

7. Parks ET. Errors generated with the use of rectangular collimation.

Oral Surg Oral Med Oral Pathol 1991; 71: 509513.8. Bridgman JB, Campbell DJ. An update on dental radiology: quality

and safety. N Z Dent J 1995; 91: 1621.

Figure 2 Mean film re-exposure values of students in a 1-year period (by quarter)

Comparison of re-exposure ratesComparison of re-exposure ratesM Mupparapu et al8

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