Annals of Diagnostic Paediatric Pathology

100
available literature. Enamel is described as poorly mineralized,
less hard and more brittle, or as more susceptible to damage by
acids while preserving normal hardness. Independent on the
mechanism of radiation-induced lesions in mineralized tissues
of teeth, they become more susceptible to harmful factors [5].
There is little data concerning the effects of chemotherapy not
combined with radiotherapy on teeth. Nevertheless, they show
its deleterious effect on the function of dental pulp, thereby
increasing susceptibility of teeth to various pathologic processes
[10]. The effect of particular cytostatics on tooth pulp is difficult
to ascertain. This is due to general use of multi-drug chemotherapy
regimens. Toxic effects of vincristin are known the
best. Histopathologic examination of teeth extracted from patients
undergoing multi-drug chemotherapy revealed linear lesions,
most probably resulting from disturbed production of
collagen matrix by odontoblasts. An important point is finding
of correlation between the number and distribution of these lines
and chemotherapy cycles, when one of administered drugs was
vincristin [6]. It is also well known that colchicin and vinblastin
block dentin formation in incisors in rats, while trethanomelamin
and cyclophosphamide delay cutting of molars in these animals
[6, 7].
Adverse change of oral eco-system in patients undergoing
anticancer treatment is caused mainly by qualitative and
quantitative disturbances of salivary secretion [9]. Facial irradiation
often leads to dysfunction of serous cells of parotid
gland. Depending on total absorbed dose of radiation (over
60 Gy), this may lead to total (irreversible) or partial (reversible)
xerostomia and to qualitative change of saliva, such as
increased viscosity, decreased buffering properties and decreased
IgA level. A decreased volume of secreted saliva may
accompany administration of many cytostatic drugs [2, 4, 9].
Increased acidity of oral cavity may be further enhanced by
vomiting, which often accompanies chemotherapy. An extremely
unfavorable aspect of chemotherapy is its prolonged
administration, ranging from 6 months to 3 years, depending
on the kind of neoplasm.
Unfavorable alteration of oral eco-system in patients undergoing
oncologic treatment may enhance demineralization
of teeth, thus increasing the susceptibility of teeth to cariespromoting
bacteria, leading to the development of caries and
erosion of enamel. Particular form of pathologic process (caries
and/or erosion) depends mainly on acid pH and duration of
its contact with mineralized tissues of teeth [2]. Increased susceptibility
of teeth to the influence of deleterious factors (chemical,
bacterial and mechanical) may be an important factor particularly
in children and adolescents, where it is caused not only
by the neoplasm itself and anti-cancer therapy, but also by morphologic
and functional immaturity of teeth [15, 16].
When discussing the etiology of damage to mineralized
tissues of teeth observed in patients undergoing anti-cancer
treatment, we must also take into account the effect of
neurologic deficits, e.g. weakness of chewing muscles leading
to “lazy” chewing and compromising self-purification of
oral cavity. Other important factors are: co-existing stomatitis,
disturbed taste, lack of appetite and general malaise, leading
to hygienic neglect and dietary mistakes.
There is no published data concerning the profile of structural
changes in mineralized tissues of teeth, developing in children
undergoing chemotherapy combined with facial irradiation.
Aim of the study
The aim of this study was clinical assessment of lesions in
mineralized tissues of teeth in children subjected to chemotherapy
combined with radiotherapy to the facial region and
an electron-microscopic analysis of structure of atypical defects
present on smooth surface of primary teeth.
Material and method
Patients. The study included 88 children (57 boys and 31 girls)
aged from 3 to 18 years, who underwent combined anti-cancer
treatment. Time since completion of oncologic treatment
ranged from 6 months to 5 years. Patients’ characteristics concerning
basic diagnosis, total dose of radiation and location
of irradiated area (face or neurocranium), are presented in Table
1. Children included in the study have been subdivided into 3
subgroups: those with primary dentition, those with mixed
dentition and those with permanent dentition (Table 2).
Stomatologic assessment of dentition. Dental examinations
were performed in the setting of a dental office, using
a shadowless lamp, dental probe and dental mirror. Primary
assessed parameters included: oral hygiene and dental status,
presence of caries, fillings, non-caries-mediated enamel defects
and missing teeth. At the same time, prophylactic and
therapeutic requirements were defined and secondary endpoints
were assessed, such as frequency and severity of caries,
treatment index and incidence of atypical non-caries-mediated
defects.
Oral hygiene. Oral hygiene was assessed using the
“Oral Hygiene Index” according to Green and Vermillion
(OHI-S). Dental plaque stained with eosin was evaluated on
buccal/labial and palatal/lingual surfaces of 6 representative
teeth: 55 (15), 53 (13), 51 (11), 75 (36), 73 (13), 71 (31). If
the desired tooth was missing, the adjacent tooth was examined.
On the basis of mean values of the OHI-S index, oral
hygiene was considered good if the score was 0-1,0; adequate
if the score was >1,0-2,0 and poor if the score was >2,0-3,0.
Severity of caries. Evaluation was performed according
to the DMF index for permanent teeth and the dmf index for
primary teeth. The following lesions of mineralized tooth tissues
were considered as atypical: white smooth stains, white or
rusty rough stains, enamel defect within a white or a rusty stain.
Structure of defect surface. Teeth were cut along the longitudinal
axis and transversely at the defect level. They were
fixed in 4 % glutaraldehyde solution (Serva) in 0.1 M cacodyle
buffer with pH value of 7.3 (BDH Chemicals Ltd, Poole, England)
and next they were dehydrated using increasing concentrations
of ethyl alcohol and acetone. Tooth fragments were attached
to brass rods with silver paste (AGAR, England) and
vacuum-coated with charcoal and gold powder and finally analyzed
using a scanning electron microscope (JSM 35C, Jeol).