The evaluation of advice given by health care professionals to pregnant patients regarding dental radiography
C Kaher Department of Oral and Maxillofacial Surgery
A Pinto Department of Oral and Maxillofacial Surgery
P Gupta Department of Paediatric Medicine*
New Road, Whitechapel, London, E1 1BB, UK
*Queen Elizabeth Hospital, Gayton Road, Kings Lynn, PE30
Pregnancy can be associated with an increased incidence
of dental disease. Dental radiographs may be necessary for
the correct diagnosis and treatment planning of patients
who may be/are pregnant. Recommendations on dental
radiography in pregnancy by different healthcare
professionals can be conflicting and confusing. This in turn
can lead to unnecessary anxiety and stress for pregnant
patients. Current guidelines suggest that dental radiography
in pregnancy delivers such a small dose to the foetus that
the associated risks can be regarded as negligible. Pregnant
patients misinformed as to the risks to the foetus after dental
radiography can undergo significant psychological distress,
this has its own risks to the unborn child. This study surveyed
current advice given about the safety of dental radiography
during pregnancy by different groups of healthcare
professionals. These included general medical practitioners,
general dental practitioners and midwives. Substandard
knowledge and misinformation on dental radiography in
pregnancy and its risks were common amongst all
The purpose of this study is to investigate the knowledge
amongst health care professionals of current Health
Protection Agency (HPA), (previously known as the National
Radiological Protection Board (NRPB)) guidelines regarding
dental radiography in pregnant females and determine if
further information needs to be targeted to healthcare
professionals involved in pregnant patient care.
The study was initiated as a result of concern elicited
amongst some of the Authors’ pregnant patients who had
been misinformed by their healthcare professionals with
regard to dental radiography and its harmful effects to the
foetus. This in turn caused the pregnant patients much stress
and anxiety, due to the concern raised about the possible
The current Guidance Notes for Dental Practitioners on the
Safe Use of X-Ray Equipment state, “A dental radiograph
delivers such a small dose to the foetus that the associated
risk can be regarded as negligible.” 1. A survey of 372 dentists
in the Birmingham and Manchester areas regarding factors
influencing their prescription of bitewing radiographs, found
95.6% of them were influenced or strongly influenced not to
take them in patients that were pregnant2. A further survey
of 2,257 dentists in the USA, found 63.1% would not take a
radiograph in a pregnant patient with toothache, in the first
trimester. 3. A comparable result has also been found
In an extreme case; following three periapical radiographs in
a female patient undergoing endodontic treatment, who
later learned she was pregnant at the time, was advised by
her GMP to have a termination, due to the potential
hazardous effects of the radiation, as she was not wearing a
Recommendations on dental radiography in pregnancy by
different healthcare professionals can be conflicting and
confusing. This in turn can lead to anxiety and stress for
The study took the form of a survey, which was answered by
general medical practioners (GMP’s), general dental
practitioners (GDP’s) and midwifes. A total of 441
questionnaires were sent out. 141 to GDP's and 150 to both
GMP's and midwives. Each of the 3 healthcare professional
groups completed 100 questionnaires. A response rate of
71%, 67% and 67% respectively) The survey was in the form of
a closed ended questionnaire. Questionnaires were sent to
local surgeries (dental and medical) and midwife offices as
well as local post-graduate courses. There were six sections.
The first part of the questionnaire assessed the frequency of
advice sought from pregnant patients with regards to dental
radiography. The second part assessed the healthcare
professionals’ beliefs with regard to the justification of dental
radiography in pregnant patients with dental pain. The third
part assessed their perception of the harmful effects of
dental radiography to the unborn child. The fourth attained
information on the current advice respondents
recommended regarding dental radiography in pregnancy.
The fifth asked whether the respondents were aware of
IR(ME)R 2000. The sixth asked what respondents thought the
dosage of a small intra-oral radiograph was equivalent to in
The majority (84%) of GDP’s were asked about dental
radiography by pregnant patients more than once a year.
GMP’s and Midwives were asked less often about them.
Although just over 40% of both groups reported being asked
about them more than once a year. Figure 1 shows the
frequency of advice sought from pregnant patients
Frequency of Advice Sought Enquiries per year
The majority of all groups (62-70%) agreed dental
radiographs in pregnant patients suffering from dental pain
were justified. Surprisingly, a higher proportion of GDPs (38%)
than the other groups thought they were not justified. Figure
2 shows current beliefs in regards to whether dental
radiography in pregnant patients with dental pathology
Are Dental Radiographs Justified in Pregnant Patients in pain? Respondents
The majority of all professionals (80-87%) believed dental
radiography maybe or was harmful to the unborn child.
Figure 3 shows the perceived danger of dental radiographs
Perceived Danger to the Unborn Child Response
The majority of responses in all groups indicated that they
advise dental radiography be avoided if possible. 14-18%
would not recommend dental radiography, even if needed.
With 14-20% of respondents recommending the radiograph
be delayed until after birth. Figure 4 shows current advice
given in regards to dental radiography and pregnant
patients by health care professionals. Interestingly, 10-25% of
respondents would recommend them with the patient
wearing a lead apron. No GDP’s or GMP’s and only 1% of
midwives would recommend dental radiography with no
Would you recommend dental radiography if needed by a pregnant patient? Response
The fifth question ascertained current knowledge of IR(ME)R
2000. Encouragingly, the vast majority of GDP’s (92%) were
Figure 5 shows awareness of the current Ionising Radiation
Are you aware of the IR(ME)R 2000? Respondent
The final question ascertained beliefs on the radiographic
equivalence of a small intra-oral radiograph. The majority of
GDP’s (70%) gave the correct equivalence of about 2 hours
on an airplane. The majority of GMP’s and midwives
overestimated the dosage, comparing it to an 8 or 20 hour
flight. Figure 6 shows the perceived radiographic
equivalence from a small intra-oral dental radiograph
Radiographic equivalence of a small intra- oral dental radiograph Hours in an airplane
Gingivitis, pyogenic granuloma, caries and erosion have all
been associated with pregnancy6,7,8. Several studies have
shown an increase in gingivitis in pregnant patients
compared to post delivery or non-pregnant females9,10.
Pregnant patients are known to have increased levels of sex
hormones. Receptors for these hormones have been found
in the gingival tissues, which are thought to make these
tissues more reactive to plaque11. These sex hormones are
also metabolised by gingival bacteria, prevotella species
and possibly P. intermedia 6,12. The ratio of sub-gingival
anaerobic to aerobic bacteria has been shown to increase
during pregnancy13. Whether or not plaque increases during
pregnancy is controversial with studies showing both
outcomes6. It is currently thought there is an increased
gingival vascular response to pre-existing plaque during
pregnancy, leading to a higher incidence of gingivitis and
pyogenic granulomas. The latter is thought to affect up to
Evidence suggests an increase in the number of salivary
cariogenic micro-organisms in pregnancy14, concurrent with
a decrease in salivary pH and buffer effect15. The effect of
pregnancy on the initiation and progression of caries is
unclear6. It is also difficult to estimate, as caries can take
years to initiate and develop. DMF was found to be higher in
women with children compared to those without16.
Erosion of the teeth may occur due to hyperemesis
gravidarum (morning sickness). This is most often seen on
The term stress describes a state of threatened
“homeostasis.” The disturbing forces maybe described as
“stressors.” These include psychological (i.e. anxiety),
physiological (i.e. mal-nutrition), physical, or biochemical
factors. Stress during pregnancy may lead to fetal distress,
miscarriage, pre-eclampsia, pre-term delivery (PTD), low birth
weight (LBW) and other delivery complications as well
increasing the risk of the child to develop diseases in the
subsequent periods of life17,18,19. The effects are thought to
be brought about by the two components of the stress
response system; corticotropin-releasing hormone (CRH) and
hypothalamic-pituitary-adrenal axis system along with the
autonomic nervous system (locus ceruleus-norepinephrine
system (LC/NE)). CRH has been shown to prepare the foetus
for parturition. Elevated levels, found in stress are linked to
pre-term parturition. These pathways alter the neuro-
endocrine systems of mother and foetus and are thought to
bring about the noted complications17,18,19,20.
It is reasonable to assume a pregnant patient who has been
told, subsequent to a dental radiograph, that the x-ray was
harmful to the foetus, will elicit a prolonged stress response,
until informed otherwise or delivery. The authors have found
this situation in their personal experiences. Putatively, the
stress caused by the misinformation given by some
healthcare professionals may cause more harm to the
foetus, from psychological distress than any dental
Further studies are needed to determine the effect this stress
has, if any, on the foetus, and if the risk to the foetus from
stress is higher than the risk from ionising radiation.
Regulation 6(1)(e) of the Ionising Radiation (Medical
Exposure) Regulations (IR(ME)R) 200021 prohibits the carrying
out of a medical exposure of a female of child bearing age
without an enquiry as to whether she is pregnant if the
primary x-ray beam is likely to irradiate the pelvic area. This is
not normal y relevant in dental radiography. However,
dental radiography is often avoided in pregnant patients,
essentially for psychological reasons. An acceptable course
of action would be to explain to the patient that a dental
radiograph delivers such a small dose to the foetus that the
associated risk can be regarded as negligible. However,
because of the emotive nature of radiography during the
pregnancy, the patient could be given the option of
delaying the radiography. Lead aprons are not
recommended and only indicated in the rarely used vertex
occlusal radiograph where pregnancy cannot be ruled out
According to the HPA, normal selection criteria for dental
radiography do not need to be influenced by the possibility
of a female patient being at any stage of a pregnancy22.
In order to allow meaningful comparisons between various
sources of radiation, the Background Equivalent Radiation
Time (BERT) unit has been established. BERT is the number of
hours, days, weeks, months or years of exposure to natural
background radiation that would equate to an adult
receiving the same ‘effective dose’ from generated ionising
radiation sources such as a dental X-ray machine. Some
examples of radiation doses expressed as BERT are listed in
Table 1 shows examples of common investigations and their
dose equivalent of Background Equivalent Radiation Times
Table 2 shows typical effective doses for a range of dental
The risk of any teratogenic effect related to a 1cGy
(10000μSv)‡ exposure (which is more than 1000 full mouth
intra oral radiographs, with E-Speed films and rectangular
collimation) is given as 0.1% or less. This is at least 1000 times
less than the anticipated risk of spontaneous abortion,
malformation or genetic disease. The gonadal dose to
women from a full mouth radiographs, is less than 0.01μSv,
which is at least 1000-fold below the threshold shown to
cause congenital damage to newborns25. Animal and
human studies support the conclusion that no increase in
gross congenital anomalies or intrauterine growth retardation
occurs as a result of exposures during pregnancy totalling
less than 5-10 cGy (50000-100000μSv)26.
One report has estimated the risk of a first generation fetal
defect from a dental radiographic examination to be 9 in 1
billion. The risk is even lower with faster films and digital
To put these figures into perspective, the gonadal/fetal dose
of 2 periapical dental films is 700 times less than 1 day of
average exposure to natural background radiation in the
Fetal radiation exposure risk is minimised by the use of
routine, safe dental radiographic procedures. These include
high-speed films (F-speed), rectangular collimation, filtration,
panoramic rare earth screens, high voltage (60-70kV+), DC
potential, focus to skin distance (fsd) of 200mm and a quality
assurance program23. Table 2 demonstrates reduction of the
effective dose using dose limiting techniques.
Despite the negligible risks of dental radiography, the dentist
should not be cavalier regarding its use during pregnancy.
Radiographs should be used selectively and only when
necessary and appropriate to aid in diagnosis and treatment
‡1cGy(0.01 Gy)= 1 rad (roentgen, R) = 0.01 sievert (Sv)=
The survey showed current knowledge amongst healthcare
professionals regarding dental radiography in pregnancy is
inadequate, with 80-87% of respondents believing dental
radiographs maybe or are harmful to the unborn child.
Indeed, a higher proportion of dentists (38%) than other
healthcare professionals thought dental radiography in
pregnant patients with dental pathology causing pain, was
not justified. Perhaps, more concerning is the misinformation
frequently distributed to patients from all healthcare groups.
According to the HPA guidelines1 and the vast majority of
research around the subject, it is safe to take dental
radiographs in pregnant patients, providing the primary
beam is not directed at the foetus. It is therefore interesting
that no GDPs, GMPs and only 1% of midwives in this survey
would recommend dental radiography if a pregnant patient
The authors acknowledge the forth question on the survey
was poorly constructed. Would you recommend dental
radiography if needed by a pregnant patient? The question
was subjective and some respondents may have taken it to
The vast majority of dentists were aware of the IR(ME)R 2000,
however the vast majority were not aware of it’s advice in
regard to dental radiography in pregnancy. The survey
would suggest more needs to be done to teach current
guidelines to the various healthcare professionals involved in
pregnant patient care. Further work is required to ascertain
the best way of imparting knowledge regarding dental
“Justification, Optimisation, Limitation” are the principals
governing the practice of radiography1. Thus the justification
should be reviewed to ensure that only radiographs that are
absolutely necessary are taken, e.g. delay routine periodic
checks. The patient should be reassured that a minimal dose
is being employed and the patient given the option of
delaying the radiograph. Foetuses are more radio-sensitive
than adults28. Thus, it may be prudent to use a protective
lead apron when taking the infrequently used vertex
occlusal radiograph1. The correct positioning of the patient
and use of a thyroid collar, can prevent the x-ray beam from
the upper standard occlusal (USO) radiograph from placing
Dentists have professional obligations not only to limit the use
of radiographs to potentially beneficial situations but also to
take good quality diagnostic radiographs, to limit the dose,
to use good radiation safety measures and to use modern
equipment to achieve best possible films. Radiographs must
then be properly developed and viewed under appropriate
conditions to gain the maximum diagnostic information from
each exposure. Quality assurance programs to ensure this,
including radiographic audit are now legally incumbent on
dentists to perform. The aim is to ensure consistency in the
quality of radiographs, while keeping any radiation exposure
to a minimum in both patients and staff23, 29, 30.
According to the General Dental Council, All UK dentists are
required to complete 250 hours of Continued Professional
Development (CPD) every five years. It is recommended
dentists should attend at least 5 hours of courses containing
“core of knowledge” (dental radiography and radiology)
every 5 years31. This knowledge is also important for
obtaining informed consent prior to taking radiographs.
Encouragingly, between 1964 and 1993 the radiation
exposure of intra-oral radiographs has been shown to have
fallen to 1/6 of its original value back in 196432. One of the
main reasons for radiation exposure decreases has been the
advent of faster films over time. The dose advantage gained
from using an E-Speed file compared to a single emulsion
film used in the 1920’s, represents approximately 50-fold
reduction in patient exposure33. Indeed, converting from D-
Speed films to E-Speed films cuts radiation exposure by 50%33,
with a similar reduction when converting to F Speed. Digital
imaging decreases exposure levels significantly up to 75%29
and with the decreasing costs of this technology, this will
become an increasingly attractive option when purchasing
dental radiographic equipment. This trend of decreasing
exposure levels should continue into the future with the
advent of new technologies and techniques
The value of lead aprons during radiography in pregnancy
has come into question. It is thought that the apron may
potentate the effect of scatter radiation that gets under the
apron since the scatter beams become trapped between
the apron and the body and are then reflected back
toward the tissues they are supposed to protect4. Since the
risk of malignancy from scatter radiation (without an apron)
is perhaps in the order of one in 100 million, and since only a
small percentage of the primary beam is scattered with
modern machines, the value of lead aprons is therefore
questionable and is discouraged. However, lead aprons do
provide some psychological security for patients and they
have been recommended for essentially this reason4.
The National Commission of Radiation Protection and
Measurements (USA) reports that production of congenital
defects is negligible from fetal exposures of 50000μSv. This
amount is unlikely to ever to be reached in dental practice.
To further protect pregnant workers, the pregnant operator
should wear an x-ray detection film badge and stand more
than 6ft from the tube head and position herself between 90
and 130 degrees of the beam, preferably behind a
The results of this survey suggest current knowledge on dental
radiography and pregnancy amongst healthcare
professionals is poor. The majority of whom believe the
associated risks are much greater than they actually are,
with most healthcare professionals misinforming patients
compared to current guidelines. The misinformation given
can cause much unnecessary psychological distress to the
mother to be. Targeted information regarding dental
radiography and pregnancy needs to be disseminated to
healthcare professionals involved with pregnant patient
I would like to thank Dr Jimmy Makdissi, Dr Eric Whaites and
Dr Colin Cook, for all their help and advice.
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