Enamel defect of primary dentition in SGA children in relation to onset time of intrauterine growth disturbance

Background: Prenatal disturbances disturb the development of organs resulting in small for gestational age (SGA) babies and also causes enamel defects in primary teeth. There are disturbances occur in the beginning of pregnancy causing symmetrical SGA, and asymmetrical type of SGA, where the disturbances occur late in pregnancy. Purpose: This research was to determined differences in severity of enamel defect of primary dentition in small for gestational age children based on the time of intrauterine growth restriction. Methods: This was a clinical epidemiological cohort study. The Ponderal index was used to determine SGA type. The subjects were 129 SGA children aged 9-42 months, 82 with asymmetrical SGA and 47 with symmetrical SGA. Two hundred normal birth weight children were the control group. Intra-oral examinations to determine enamel defect used the FDI modification of the Developmental Defect of Enamel score at 3 months intervals. Statistical t-tests were used to test the difference in severity of enamel defect, and chisquare to find out the difference of Relative Risk Ratio (RRR). results: The results showed that the enamel defect scores of symmetrical SGA were significantly higher than those with asymmetrical SGA. RRR for severe defect was also significantly higher in symmetrical type for anterior and canines. Conclusion: The study suggested that the severity of enamel defect for infants with symmetrical SGA was higher than those with asymmetrical SGA, indicating that the severity of the defect occurs in the beginning of pregnancy is more severe than in the late pregnancy.


Kata kunci: Defek email, kecil masa kehamilan, simetri, asimetri, hambatan pertumbuhan intrauterin
Correspondence: Willyanti Soewondo Sjarif, c/o: Kedokteran Gigi Anak, Fakultas Kedokteran Gigi Universitas Padjadjaran.Jl.Sekeloa Selatan 1 Bandung 40132, Indonesia E-mail: willyantir@yahoo.comintroduction Small for gestational age (SGA) describes a newborn infant with birth weight less than normal for its gestational age, to the extent of being under the 10 th percentile of the intrauterine growth curve.These kinds of deliveries might .These kinds of deliveries might cause many problems in the future including morbidity and mortality.In general, SGA neonates are in poor condition are in poor condition and are at high risk for both their short term and long term health.0] The prenatal period is a critical 2][13][14][15][16][17][18] Overall, the incidence of enamel defect in primary dentition is defect in primary dentition is in primary dentition is 22-33%.
][3][4][5][6][7] Symmetrical SGA infants have disturbances in both brain and physical growth as shown by delayed growth of head circumference, body length and body weight, but the whole body is in good proportion.2][3][4][5][6] Determination of SGA Type therefore requires an accurate record of gestational age, birth length and head circumference.
In general the clinical manifestation is worse in symmetrical SGA infants than in asymmetrical ones.2][3][4][5][6][7][8] Overall, 71% of enamel defect in primary dentition are caused by prenatal systemic factors, the effect of developmental disturbances occurring at the beginning of dental forming and calcification during the first, second or third trimester of pregnancy, and manifesting as hypoplasia or hypocalcification.2][13][14][15][16][17][18] Enamel defect might also worsen enamel quality and cause easier accumulation of plaque that trigger caries occurence.Untreated caries can then cause abscesses, resulting in premature loss of primary dentition.One of the predispositions to caries is the anomaly of enamel structure that is involved with prenatal developmental growth disturbances.2][3][4][5][6][7][8] In Indonesia and other developing countries IUGR is still a main health problem,with the highest mortality rate The cause of IUGR might be placental, foetal and maternal characteristics such as the age of mother older than 35 years old or young mother, short and thin stature, or low increase of body weight during the third trimester of pregnancy.2][3][4][5] Family with low socio-economic conditions can result in bad nutrition in pregnant mothers that affects inter-uterine health.] The goal of the study was to determine the differences in severity of enamel defect in the primary dentition of defect in the primary dentition of in the primary dentition of SGA infants, based on the onset of intrauterine growth disturbance.It is important to predict the severity of the It is important to predict the severity of the defect, to determine prognosis and treatment planning.

materials and methods
The subjects was of this study were 129 SGA infants, the s was of this study were 129 SGA infants, the was of this study were 129 SGA infants, the 129 SGA infants, the SGA infants, the age range 9 to 42 months, born in Hasan Sadikin General Hospital, Universitas Padjadjaran Bandung Indonesia.As Bandung Indonesia.As group consisted of 200 infants with normal birth weight consisted of 200 infants with normal birth weight (appropriate for gestational age-AGA) in range of age 4 to ) in range of age 4 to 42 months and caries free was used as control group.
free was used as control group.The different of the SGA and AGA youngest subjects youngest subjects was in accordance with a study conducted by Willyanti that SGA children had delayed eruption of teeth compared to to AGA children.
children. 20Inclusion criteria also required complete also required complete data of birth; for mothers and children, and an exclusion of birth; for mothers and children, and an exclusion for mothers and children, and an exclusion criteria was infants with general anomalies (such as genetic (such as genetic (such as genetic anomaly).This was a clinical epidemiological ambispective ical ambispective cohort study, with given sample sizes.After obtaining given sample sizes.After obtaining obtaining informed parental consent, and completing physical examination of SGA (and AGA/control) patients, the (and AGA/control) patients, the (and AGA/control) patients, the the enamel anomaly or enamel defect and presence of dental caries were determined.
Scoring for hypoplasia and hypocalcification using for hypoplasia and hypocalcification using and hypocalcification using modified Developmental Defect of Enamel (DDE) of Federation Dental Internationale (FDI). . 21The subjects were examined three times, at one month intervals, to determine at one month intervals, to determine whether there were enamel defects on new teeth.The development of dentition was monitored in case there was of dentition was monitored in case there was was monitored in case there was any defect on the next erupted tooth.with only Subjects with only 1 or 2 teeth erupted were monitored, and examination on , and examination on subyects with primary dentition fully erupted.fully erupted. .Small for gestational age (SGA) is defined if the baby a is defined if the baby a defined if the baby a baby was born with birth weight under the 10 th percentile of Lubchenco curve of intrauterine growth and development of weight for gestational age.Type of SGA was determined was determined using the Ponderal index.length Birth 100 x weight Birth = Index Ponderal Type of SGA was defined as symmetric if the Ponderal index scores was 20 to 25 and asymmetric if the Ponderal index scores was either less than 20 or more than 25.Severity of enamel defect of primary dentition was identified as extent of hypoplasia/hypocalcification.2][13][14][15][16][17][18][19] Dental examination was done using a mouth mirror, explorer, and probe with paper lighting.The teeth surface were cleaned, dried using a cotton role, then examined to record any defects on primary dentition.
Enamel hypoplasia/hypocalsification (EHP) score 1 (normal) was determined when the enamel transparent; score 2 (opacity) when the enamel opaque/ white, not transparent, or yellowish/ brownish; score 3 when there were pits and fissures on some of teeth surface; score 4 when there was un-neat vertical fissures; score 5 when there were exact horizontal fissures; and score 6 when most of the enamel missing or teeth were smaller.Scoring used the FDI modification of the Developmental Defect of Enamel (DDE) for enamel hypoplasia/ hypocalcification (EHP) and an index of enamel defect severity (EDS) was determined as follows; 21 Index enamel defect severity (EDS) was determined using the FDI modification of Developmental Defect of Enamel (DDE) as follows: Enamel Defect Score (EDS) = EHP x Total dentition with defect x 10 Total teeth at risk The degree of severity of enamel defects of primary dentition was then classified relative to a statistical cut-off point of a median score of 12 determined from a Kruskal Wallis test (Normal 0; mild/light 1-12; and severe >12).Difference of enamel defect severity of primary dentition based on onset of intrauterine developmental growth disturbance was compared using a t-test.Chi-square was used to determined differences in incidence of enamel defect based by type of SGA and to differentiate enamel defect risk rates based on stage of intrauterine developmental growth disturbance.Risk ratios of symmetric against asymmetric SGA based on severity of defect, on anterior, canine and posterior teeth were separately tested by t-test.

results
Small for gestational age (SGA) infants had more severe enamel defect of primary dentition (EDS mean: 12.27) than AGA control infants (EDS mean: 0.39) (Table (Table  1).Type of SGA related to incidence of enamel defect.Enamel defect affects 100% of infants with symmetric SGA and in asymmetric SGA still high but less at 75.6% (Table 2a), while the mean score on symmetric SGA infants was significantly higher (15.29) than for asymmetric SGA infants (10.38).It indicated that the enamel defect of primary dentition is more severe in the symmetric SGA compared with the asymmetric SGA condition (Table 2a).
Symmetric SGA infants were at significantly higher risk of both light and severe enamel defects on their anterior teeth than asymmetric SGA infants -3.74 times at risk of light enamel defect and 7.11 times at risk of having severe defect (Table 3).Symmetric SGA infants were at at significantly higher risk of both light and severe enamel defects on the caninus teeth than asymmetric SGA infants caninus teeth than asymmetric SGA infants than asymmetric SGA infants -2.19 times at risk to have light defects and 2.96 times at 2.19 times at risk to have light defects and 2.96 times at s and 2.96 times at 2.96 times at risk to have severe defects (Table 4).Symmetric SGA .Symmetric SGA Symmetric SGA infants were at higher risk of both light and severe enamel defects on the posterior teeth than asymmetric SGA infants posterior teeth than asymmetric SGA infants (although this was less significantly so for light defects) -1.42 times at risk to have light defects and 1.93 times at 42 times at risk to have light defects and 1.93 times at and 1.93 times at risk to have severe enamel defects (Table 5).

discussion
The study showed that enamel defect score (EDS), enamel defect score (EDS), based on the FDI modification of the Developmental Defect of Enamel (DDE) score for enamel hypoplasia/ hypocalcification (EHP), was higher in SGA compared to AGA infants, indicating that the enamel defect inprimary dentition is more severe for SGA than for normal AGA infants.This is because the IUGR causing SGA in infants the IUGR causing SGA in infants occursin the early foetal prenatal period, a critical period of primary dentition development. . 8IUGR at that stage causes disturbances/anomalies of the organs, including primary dentition. . 22,23The results showed that enamel The results showed that enamel defect of primary dentition in SGA might affect several or even all types of teeth, bilaterally An interaction of types of teeth, bilaterally An interaction of genetic and environmental factors might effect the growth and development of dentition, and local environmental factors may have effect the growth of teeth environmental.
may have effect the growth of teeth environmental.may have effect the growth of teeth environmental.e growth of teeth environmental. .Stewart and McDonald state that systemic factors might be the whole cause of enamel defect. 16,24ur study has also shown that the enamel defect anomalies were more severe in SGA infants.Also the were more severe in SGA infants.Also the .Also the results indicate variation in severity of enamel defect according to the type of SGA, in EDS/DDE score was was higher (more severe defect) in the primary dentition of (more severe defect) in the primary dentition of defect) in the primary dentition of defect) in the primary dentition of infants with symmetrical type of SGA.It seems that this is because for them the anomaly occurs earlier, i.e. during the first trimester or embryonic phase critical for dentition, or embryonic phase critical for dentition, ic phase critical for dentition, critical for dentition, critical for dentition, and for the asymmetric type it occurs later at the end of the second or third trimester or foetal phase.
or foetal phase. .It was also seen in this study there was no hypoplasiain this study there was no hypoplasiain was no hypoplasiain the asymmetrical type, while in the symmetrical type there were both hypoplasia and hypocalcification.
were both hypoplasia and hypocalcification.both hypoplasia and hypocalcification.Hypocalcification in the asymmetrical type is a milder anomaly of the structure compared with hypoplasia.It is It is It is a disturbance sof enamel matrix calcification that occurs sof enamel matrix calcification that occurs f enamel matrix calcification that occurs rix calcification that occurs s after the 16 th week of pregnancy.Hypoplasia is an anomaly caused by disturbance of matrix forming by ameloblast-f matrix forming by ameloblastdisturbance of matrix synthesis or the resorbtion that causes disturbance on the next mineralization.][3][4] As a result of IUGR during embryonal phase or foetal phase that might disturb dentition development, SGA infants may have hypoplasia and hypocalcification.[17][24][25][26] In our study, the symmetrical type SGA had more severe enamel defect than asymmetrical type because the defect occured during the embryonic the embryonic phasecritical phase for organogenesis.critical phase for organogenesis. 29,30Some of the SGA (24.4%) had no anomalies because the calcification ecause the calcification process had completed when the disturbance/anomaly occured (Table 2a).
(Table 2a).The results showed that the incidence of enamel defect results showed that the incidence of enamel defect defect of primary dentition in symmetrical SGA was higher than in asymmetrical SGA and the defect was more severe too.
and the defect was more severe too.was more severe too.This is in accordance with statements in previous studies that anomalies which occur during the embryonic period (1 st trimester) will be more severe than those occurring later during the foetal period (middle of 2 the foetal period (middle of 2 the foetal period (middle of 2 nd and 3 rd trimester) because the foetus is in highly sensitive condition-cell proliferation and highly active with the cell number increase and highly active with the cell number increase with the cell number increase the cell number increase more than the cell size.Disturbance during the embryonic Disturbance during the embryonic period may therefore decrease the amount of cells.[29]  Enamel is the hardest tissue on which calcification hich calcification might occur, consisting of crystals with 96% inorganic material, and only 4% water and organic material.Enamel is formed by an extracellular matrix from the synthetic and protein secretion by ameloblasts.Enamel, which is only formed once, is different to cartilage or bone and will not regenerate and resorb. . 8,25,30Enamel defect might occur in the amelogenesis period, i.e. matrix in the amelogenesis period, i.e. matrix aposition process and mineralization since the beginning of the 4 th month of pregnancy.Aposition is the end stage of morphodifferentiation.Matrix forming consists of secretion and maturation, enamel matrix starts as an occlusal part of dentition.The first calcification begins on the 4th month prenatal up to the antenatal period.During up to the antenatal period.During amelogenesis the ameloblast is highly sensitive to what to what might disturb its activities and any disturbance might result in enamel defect in the form of hypoplasia and also defect in the form of hypoplasia and also hypocalcification-hypoplasia being shortage of enamel -hypoplasia being shortage of enamel matrix, and hypocalcification being when the enamel matrix is sufficient but there is shortage of calcification.
13][14][15][16][17]24 Prenatal environmental factors s that might be the cause of enamel defect of the teeth are defect of the teeth are maternal factors such as severe infectious disease at the beginning of pregnancy, chronic infection, long lasting malnutrition, premature and low birth weight.Mother's diseases during pregnancy such as maternal diabetes, hypertension, maternal alcoholism, torch, high fever at the beginning of pregnancy, might also cause hypoplasia, 16 and might also result in SGA.
The possibility (Relative Risk Ratio: RRR) of (Relative Risk Ratio: RRR) of severe defect (>12) of the anterior and caninus teeth was significantly higher in symmetrical compared with asymmetrical SGA (Tables 3, 4, 5).The severe defect on .The severe defect on posterior teeth was less significant in symmetrical SGA was less significant in symmetrical SGA less significant in symmetrical SGA because the posterior teeth, especially second primary molar second primary molar are the last teeth formed.h formed.Previous studies had not looked at disturbances in prenatal growth. 21 It was exmined in this study and concluded that the severity of enamel structure anomaly of primary dentition was higher in infants with SGA, and also, for those with symmetrical SGA it is more severe than for those with asymmetrical SGA.It means that the enamel defect/anomalies that occur in the beginning of pregnancy (embryonic phase) are more severe than those that occur later (during the foetal phase).This information will be important for assisting predictive prognosis and treatment planning.It was concluded that the severity of enamel defect which occurs in the beginning of pregnancy was more severe than in late pregnancy.

table 2a .
Incidence of enamel defect based on type of SGA

table 2b .
EDS mean score based on type of SGA

table 3 .
Anterior teeth -relative risk ratio of symmetric against asymmetric SGA based on light and severe defect Anterior teeth -relative risk ratio of symmetric against asymmetric SGA based on light and severe defect -relative risk ratio of symmetric against asymmetric SGA based on light and severe defect relative risk ratio of symmetric against asymmetric SGA based on light and severe defect and severe defect

table 4 .
Caninus teeth -relative risk ratio of symmetric against asymmetric SGA based on lightand severe defect Caninus teeth -relative risk ratio of symmetric against asymmetric SGA based on lightand severe defect and severe defect

table 5 .
Posterior teeth -relative risk ratio of symmetric against asymmetric SGA based on the light and severe defect Posterior teeth -relative risk ratio of symmetric against asymmetric SGA based on the light and severe defect and severe defect