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Caries prevalence and tooth surface distribution in a group of 5-year-old Italian children.


Dental caries is still one of the most troubling problems concerning oral health in industrialised countries [U.S.A. Dept. of Health and Human Services, 2000]. In spite of the decline in caries over the past 40 years, among school children and adolescents, dental caries in preschool children has remained unchanged [Pitts et al., 2003; Hugoson et al., 2008] in this age group is a high-risk group, among many populations. As caries in primary teeth is a sign of high risk of caries in permanent teeth [Skeie et al., 2006], it is useful to identify those children affected. Moreover, as dental caries does not affect teeth and tooth surfaces in the same way, it is appropriate to be aware of the distribution.

Caries distribution within the primary dentition has been reported to follow a typical pattern [Psoter et al., 2003]. Second primary molars are most frequently affected [Gizani et al., 1999; Saravanan et al., 2005; Wyne, 2008], closely followed by first molars. In primary molar teeth, caries is frequently found on occlusal surfaces. Anterior teeth are less frequently affected and maxillary primary central incisors more often than lateral incisors and canines [Wyne, 2008]. Caries in mandibular anterior teeth is rare in the primary dentition. [Gizani et al., 1999]. Detailed knowledge of caries patterns is important as specific patterns of attack might indicate a distinct aetiology. There may be a stronger association with the subsequent development of caries on other surfaces or teeth [Gizani et al.,1999; Vanobbergen et al., 2007] or a relationship with caries of the permanent teeth [Li and Wang, 2002; Skeie et al., 2006].

Several surveys of caries epidemiology in preschool children in the Veneto area of Italy [Ferro et al., 2006; Ferro et al. 2007; Ferro et al., 2007a] evaluated prevalence and severity but only at tooth (dmft) level and without recording caries distribution patterns. Accordingly, in this study, an investigation looked at several aspects of caries beside prevalence and severity (dmft, dmfs and SiC indexes; distribution of children according to dmft/s scores). The focus was on the most affected teeth and surfaces, the presence of random, aggregated or regular caries patterns as suggested by Hujoel et al., [1994]. In addition deviations from left-right symmetry in caries distribution and in spatial associations of lesions in primary dentition among homologous surfaces were looked for. Severity and distribution prevalence of caries and any combination of patterns, as well as any link between caries occurrence in anterior teeth with lesions in posterior teeth were considered. Finally any associations among/between teeth were assessed for possible aetiology.

Material and Methods

Study population. Within the framework of a Community Oral Health Promotion Program developed by us, 15 out of 88 nursery-schools were randomly selected (one from each of the 15 school departments) in the Health District of the Veneto Region (North East Italy). There were 1,210 children aged 3-5 years old attending these schools. For the aims of this cross sectional study a sub-sample of 5 year-olds was taken as an indicator age group as suggested by WHO [Petersen at al., 2005] and for comparison with other studies/ countries [Pitts et al., 1999; Skeie et al., 2005; Saravanan et al., 2005; Elfrink et al., 2006; Pitts et al., 2007]. The study population consisted of 411 individuals (17.1% of a population of 2,400 born in the year 2000). There were 63 children (15.3%) who were not at school on the day of examination so the final sample consisted of 348 5-year-old children (182 males and 166 females). No power calculation was carried out as the number of schools selected represents the best convenience sample that the examination team could cope with. A random sample of schools was felt to provide a better description of the children population in the area.

Data Collection. The clinical examinations were performed between September 2005 and May 2006 by two trained/calibrated dental examiners in classroom settings with standard plain mouth mirrors and dental probes under artificial light with the child sitting in an ordinary upright chair. The WHO criteria [1997] were used. Caries status, decay (at the dentine level), missing and filled primary teeth (dmft) or tooth surfaces (dmfs) were assessed. SiC index was measured as the mean dmft of the one third of the population with the highest caries scores. Children's teeth were not air-dried or cleaned prior to the examinations. No radiographs were taken. Lesions on the occlusal, buccal, palatal/lingual, mesial and distal surfaces were recorded separately.

Calibration. A sub-sample of children (50) was examined prior the beginning of the study to test the inter-examiner consistency and then re-examined at a later date (1 week) to assess the intra-examiner's reliability. The agreement of the examiners was found to be very good. Analysis of the repeated examinations gave a Cohen's Kappa scores of 0.85 (inter-examiner) and 0.90 (intra-examiner).

Tooth surface assessments. For the purposes of this study the mean number of decayed and filled tooth surfaces was divided by type of surface (occlusal, proximal, buccal-lingual) and dental caries patterns:

* maxillary anterior caries (caries of maxillary incisors and mesial surfaces of the canines);

* pit and fissure caries (caries of occlusal surfaces, buccal pits of mandibular second molars and lingual grooves of maxillary second molars;

* posterior proximal caries (caries of all contacting posterior smooth surfaces and the distal surfaces of the canines).

Each child was then assigned to one caries pattern or combination of patterns [Douglass et al., 2001]. The caries patterns were assessed for: frequency as the percentage of the population experiencing one or more caries patterns, prevalence as the percentage of the population experiencing a combination of caries patterns. Severity, as the percentage of available surfaces affected in a caries pattern or caries pattern combination among children positive for that pattern/ combination was assessed. Finally, distribution, as the percentage of the total number of carious surfaces constituting a pattern or a combination of patterns was calculated [Douglass et al., 1995].

Statistical analyses. The dmfs score was the primary outcome measure in the study. Each child was furthermore classified as having caries (with dmfs>0) or being caries free (with dmfs=0): a dichotomous variable 1/0 was defined to record this information. Means and standard deviations were calculated for continuous variables, for categorical variables the results were provided as proportions. Comparisons between groups were made using Pearson chi square test. Because of a lack of normality, the distribution of dmfs scores between pairs of contiguous molars was assessed by means of Wilcoxon signed-rank test. Statistical analysis was performed with software Stata rel 8.2 (Stata Corporation, College Station, TX, USA).


The results showed that caries prevalence affected 42% of the children. ; dmft index : 1.84 [+ or -] 3.04; dmfs index : 3.6 [+ or -] 7.4 (ds 1.7 [+ or -] 5.2; ms 0.1 [+ or -] 1.1; fs 0.4 [+ or -] 1.5); SiC index : 5.32; care index (f/dmft x 100 %) : 10.2%. Table 1 shows the distribution of 5-year-old children with dmft >0 according to the total number of decayed, missing and filled teeth. In the total sample 63% of carious teeth and 72.2% of carious surfaces were found in 13.8% of children. The most affected teeth were molars (78%), especially the mandibular ones, followed by the maxillar molars (figure 1). Between each pair of contiguous molars similar caries patterns were seen (figure 2) comparing dmfs scores (a continuous variable: mean scores did not differ significantly). The same observation can be made by using a categorical variable (caries free 1/0): caries free proportion between each pair of contiguous molars showing a high association (Pearson chi square < 0.0001). This means that each molar of a contiguous pair is more likely to be found caries free if the other one of the pair is also caries free (and vice versa). The distribution of decay has been considered in order to assess the teeth/surfaces most affected by caries.



The examination of the surfaces of primary molars showed that:

* The surface most often decayed was the occlusal one,

* Proximal surfaces were affected more in first than in second molars,

* Decay occurred most often in the maxilla (53.6%),

* Almost all decay in the mandible was in molars (95.5%).

It was infrequent to find decay in the anterior teeth (12%) and rare in the mandibular anterior teeth. The most affected anterior teeth were central incisors (buccal surfaces), while the least affected ones were canines.

At the individual level, contralateral homologous teeth and/ or surfaces showed similar patterns in the distribution of caries meaning an equal probability of developing caries or "random" distribution of decays as defined by Hujoel et al. [1994]. Moreover, comparing mean dmfs scores from left to right side of each mouth showed no statistically significant differences. First and second molars, both on the left and right side, shared the same caries pattern (no statistically significant differences confronting mean dmfs scores).

Table 2 shows the frequency, severity and distribution of the caries patterns and Table 3 shows prevalence, severity and distribution of the detected caries patterns combinations in the sub-sample with dmfs>0 (n=143). The most represented pattern (93%) was "pit and fissure"; with nearly 50% of surfaces affected and the most represented combination was "pit and fissures and posterior proximal" (3.5%). The association between decay in anterior teeth and in posterior teeth was recorded in 28.7% of children (n=41).


Dental caries. No radiographs were taken for this study. As a result, some degree of underestimation of caries prevalence was to be expected with the broad and flat proximal contacts that exist between primary molars. The majority of the caries indexes constituted the d-component, as confirmed in other studies [Douglass et al., 1995; Gizani et al., 1999; Skeie et al., 2005; Skeie et al, 2006; Pitts et al., 2007] and the distribution of caries was skewed. The children examined showed a low level of restorative dental care (Care Index: 10.2%), so being particularly suitable for the study of caries patterns, as the distribution of lesions was not modified by decisions made by dentists.

Distribution of carious lesions. This study confirmed the findings of previous [Douglass et al., 1995; Johnsen et al., 1993; Hallett and O'Rourke, 2006; Elfrink et al., 2006; Vanobbergen et al., 2007; Wyne, 2008] in that:

* The most affected zone was the posterior one,

* The most affected surfaces were occlusal,

* Proximal surfaces were affected more in first than in second molars,

* Decay in the anterior zone involved most often the maxilla.

The differences observed between previous studies and this one were:

* the most affected tooth was the second molar in all previous studies whereas no significant differences of prevalence of caries between first and second molars in this study,

* the most affected arch was the maxilla in this study while in the study of Saravanan et al., [2005] it was mandible.

The carious involvement of specific tooth surfaces may be explained, in part, by anatomical features, such as occlusal lesions in primary molars, high level of caries in first molar distal surfaces due to frequently close contact between the first and second molars along with the thin enamel. However, the protection by the tongue and the opening of major salivary ducts near the lower incisors has been suggested as a reason for this resistance to caries [Dunning, 1986; Elfrink et al., 2006; Douglass et al., 1995].

Within mouth distribution. At the individual level, contralateral homologous teeth and/or surfaces showed similar patterns in the distribution of carious lesions meaning an equal probability of developing caries or "random" distribution of decays as defined by Hujoel et al. [1994]. Moreover, as found by Vanobbergen et al. [2007], the mean population caries scores did not vary in a systematic way from the left to the right side. Such an observation suggests that caries is asymmetrical disease, as found by Vanobbergen et al [2007]. Caries in the primary dentition naturally fell into the adopted surface-specific patterns theory [Johnsen et al., 1993; Douglass et al., 2001]. The recorded frequency of pit and fissure pattern being higher than the posterior-proximal might be related to the lack of using radiographs, resulting in delayed detection of proximal caries. The presence of caries in the primary dentition is a strong predictor of caries in permanent dentition [Skeie et al., 2006; Li and Wang, 2002] and, accordingly, dentists have to use this information to identify high-risk children and implement preventive programs.


Dental caries in Italian preschool children affects primary molars (particularly on the occlusal surfaces) and the distribution of carious lesions in the primary dentition follows specific symmetrical patterns.


Approval from the concerned authorities was obtained prior to beginning the study and informed consent from the parents prior to visiting the enrolled children.

The ethical principles established by the "World Medical Association Declaration of Helsinki" [World Medical Association, 2001] have been applied.


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R. Ferro *, A. Besostri *, A. Olivieri **

* Dental Unit, Regional Centre for the Study, the Prevention and the Therapy of Dental Diseases of Veneto Region, Cittadella Hospital, Cittadella (PD); ** Epidemiology Unit, Prevention, Health District no. 15 Cittadella (PD; Italy

Postal address: Dr. R.Ferro.,U.O.A. Odontoiatria--Presidio Ospedaliero di Cittadella--AULSS n.15 Via Riva Ospedale--35013 Cittadella (PD)--Italy

Table 1. Distribution of a group of 5-year-old Italian children
with dmft score > 0

dmft score >0 1-5 6-10 11-15 16-20

Percentage 42 66.40 28.00 4.90 0.70
of children (n=143) (n=95) (n=40) (n=7) (n=1)

Percentage of 100 37 47 13 3
teeth affected

Percentage of 100 28.8 48.6 19.2 3.4
surfaces affected

Table 2. Frequency, severity and distribution of caries patterns in
a group of 5 year-old Italian children.

 (% of (% available (% of total
 subjects surfaces number of dmf
 affected) affected in surfaces
 a pattern) constituting
 a pattern)

Maxillary anterior 30.8 8.6 21.8
Pit and fissure 93.0 29.1 49.1
Posterior proximal 56.6 10.4 29.1

Table 3. Prevalence, severity and distribution of caries patterns
combinations in a group of 5 year-old Italian children

CARIES PATTERNS (% available (% of total
 surfaces number of dmf
 affected in surfaces
 a pattern) constituing
 a pattern)

--maxillary 2.1 (3) 46.3 2.4
anterior only

--maxillary 1.4 (2) 7.9 0.6
anterior and

--maxillary 9.1 (13) 27.9 10.7
anterior and
pit and

--maxillary 18.2 (26) 3.5 42.0
anterior, pit
and fissures
and posterior

--posterior 3.5 (5) 8.0 0.8
proximal only
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Author:Ferro, R.; Besostri, A.; Olivieri, A.
Publication:European Archives of Paediatric Dentistry
Article Type:Report
Geographic Code:4EUIT
Date:Mar 1, 2009
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