Dental caries pattern and predisposing oral hygiene related factors in Nigerian preschool children.
|Publication:||Name: European Archives of Paediatric Dentistry Publisher: European Academy of Paediatric Dentistry Audience: Academic Format: Magazine/Journal Subject: Health Copyright: COPYRIGHT 2007 European Academy of Paediatric Dentistry ISSN: 1818-6300|
|Issue:||Date: Dec, 2007 Source Volume: 8 Source Issue: 4|
Aim: To determine the pattern of caries in Nigerian preschool children and to identify the effect of age, gender, socio-economic status, oral hygiene status, tools used in tooth cleaning and the frequency of tooth cleaning on the children's caries experience. Method: A cross sectional study involving children between the ages of 6 and 71 months with a questionnaire was administered to elicit socio-demographic information on each child. Information was also provided about the the type of oral hygiene tool used by each child and the frequency of tooth cleaning each day. An intra-oral examination was conducted to assess dental caries (dmft) and oral hygiene status. A diagnosis of rampant caries, caries or no caries was also made. Statistics: Logistic regression was used to assess the effect of age, socioeconomic status, gender, birth rank, tooth cleansing methods, tooth cleansing frequency, tooth cleansing tool and oral hygiene status on the occurrence of rampant, molar and maxillary anterior caries of each study subject. Result: Forty one (10.5%) of the 389 preschool children examined had caries. The second mandibular primary molar was 4 times more likely to be carious than a second maxillary molar. The age and oral hygiene status had significant impact on the dmft. Also the odds of having rampant caries increasing almost 4 fold with every score increase in oral hygiene status. Conclusion: There appears to be no significant age related caries distribution pattern in Nigerian preschool children. The second primary molars appear to be more susceptible to caries in preschool children in Nigeria. The oral hygiene status appears to be a risk factor for rampant caries in these children.
Key words: dental caries, oral hygiene, children
The pattern of dental caries varies between the primary to permanent dentition; within the primary dentition, the pattern also varies between first and second primary molars in both the mandibular and maxillary arches. Primary teeth are much less susceptible to caries on their occlusal surfaces than the second primary molars, even though the first primary molars erupt earlier. This difference in caries susceptibility is no doubt related to differences in morphology of the occlusal surface. The second primary molar usually has deeper, less completely coalesced pits and fissures [McDonald and Avery, 2000]. While Noah  and Tang et al.  supported the observation above, Grinderfjord et al.  reported that the maxillary incisors were most affected. Holt  also noted that relatively more children have only the incisors affected in the younger age group. Curzon  reported that while occlusal lesions in the primary molars are more common than interproximal lesions in preschool children initially, once the posterior contacts close after three years, interproximal lesions increase.
Just as the pattern of caries varies so do reports on the predisposing factors. For example, socio-economic variation exists in the epidemiology of caries. In industrialized populations a positive correlation has been established between the occurrence of dental caries and lower socioeconomic status [Vargas et al, 1998; Ramos-Gomez et al, 1999]. In many developing countries a high prevalence of dental caries has been reported amongst children of higher socioeconomic class than children from lower social class and this was attributed to dietary factors [Salako, 1985; Jeboda and Ogunbodede, 1995]. A study conducted by Tang et al.  showed a strong inverse relationship between the socioeconomic status and the dmfs score of child patients. The weight of scientific evidence today indicates that children from socially deprived backgrounds experience higher caries levels [Moynihan and Holt, 1996; Frecken 1999].
Equally, the oral hygiene (OH) status has been identified as a caries risk factor with a number of authors [Grinderjford et al., 1993; Grinderfjord et al., 1996; Vanobbergen et al., 2001] reporting a strong correlation between OH habits and the prevalence of dental caries. Increased frequency and better OH levels are associated with lower caries levels in preschool children [Correa et al., 1996; Vanobbergen et al., 2001]. Brushing with fluoride toothpaste was found to be statistically significantly related to a low prevalence of dental caries. It was suggested as a major health gain to young children if parents can be persuaded to adopt and implement this positive attitude [Hamilton et al., 1999; Sayegh et al., 2002].
Studies of caries experience in pre-school age children are less numerous than those in older children. This is relatively less so for Nigerian children. This study would be contributing to existing data with respect to caries in pre-school children. It is aimed at determining the pattern of caries in
Nigerian pre-school children and to identify the effect of age, gender, socio-economic status, OH status, tools used in tooth cleaning and the frequency of tooth cleaning on the children's caries experience. This information would help clinicians in identifying predisposing factors for caries in these children and therefore be able to design better clinical based programs to help pre-school children address caries prevention.
Materials and Methods
Population selection. The study was carried out in three randomly selected Local Government Areas (LGAs) from the list of 20 local government areas in Lagos State, Nigeria. The LGAs were stratified into urban, peri-urban (suburban) and rural areas. One LGA was chosen from the three stratifications. In the Urban and periurban LGAs the paediatric out patient clinics were used for clinical examinations while in rural LGAs, a community town hall used for the clinical examinations.
A Table of Random numbers was used in random selection of the hospitals used in the urban and periurban LGA. Permission to conduct the research was granted by the Ethical Committee, Lagos University Teaching Hospital, Lagos and the health authorities of the two hospitals used for the study. All the children between the ages of 6 and 71 months present at the study venues identified above participated after verbal consent was obtained from their mothers following due explanation of the study.
Questionnaire. This was administered at the time of the clinical oral examinations. The pre-tested structured questionnaire consisted of demographic information on each child. Information collected included the age, gender, socio-economic status and birth rank of the child. The age of the child was calculated from the date of birth in months. The appropriate age for the child was fixed as the attained age in months. The socio economic status was obtained through an index of mother's level of education and the father's occupation. This index allocated each child to a social class ranging from I to V with the social class V being the lowest [Olusanya and Okpere, 1985]. For statistical analysis, the SES was classified as high (SES I and II), middle (SES III) and low (SES IV and V) socio-economic class.
Parents were also asked to provide information on the type of OH tool or methods used for the child and the frequency of tooth cleaning each day.
Clinical examination. One of the authors (AS) carried out all examinations. A calibrating examination was carried out earlier on a group of pre-selected children who possessed the same characteristics to be assessed in the main survey in order to assess intra-examiner reproducibility of the study. This involved a group of 23 primary school students who were examined and re-examined a week later by the same examiner. Intra-examiner clinical examiner reproducibility was 100%. Necessary adjustments were made to the questionnaire and ambiguities corrected through a pilot testing of the questionnaire before the final survey. During the intra-oral examination each participant was assessed in the following sequence; the teeth present and dentition status of the child.
Dental caries. A tooth was considered present in the mouth when any part of the tooth was visible. The examination for dental caries was conducted with a plane mirror under natural light. Radiographs were not used in the study. The teeth were not dried before examination but gross debris was cleared with gauze where necessary. Caries diagnosis was based on the recommendation of the WHO  Oral Health Survey methods.
The dmft index was used in this study. A diagnosis of rampant caries, caries or no caries is made and recorded. Rampant caries was diagnosed on the basis of caries affecting one or more maxillary incisors and with or without involvement of the primary molars [Oulis et al., 1999]. Caries was diagnosed when there were carious lesions affecting the tooth exclusive of the maxillary anterior tooth/teeth. In the absence of any carious lesion, a diagnosis of no caries is made.
Oral hygiene. The cleanliness of the mouth was evaluated by assessing the plaque and debris accumulation. The OHI by Greene and Vermillion  was used to determine the OH status. The OHI-S comprises debris and calculus scores on selected tooth surfaces. However, because of the young age group involved, facial and lingual surfaces were examined on the following index teeth 51, 55, 65, 71, 75 and 85. The debris and calculus scores were added and divided by the number of surfaces examined to give the OH score as recommended.
Statistical analysis. This was done with Intercooled STATA (release 9) for windows. Simple proportions were computed. A general linear model was used to determine the effect of age, socioeconomic status, gender, birthrank, teeth cleansing methods, tooth cleansing frequency, tooth cleansing tool and oral hygiene status on the dmft score. Logistic regression was used to assess the effect of age, socioeconomic status, gender, birth rank, tooth cleansing methods, tooth cleansing frequency, tooth cleansing tool and oral hygiene status on the occurrence of rampant, molar and maxillary anterior caries of each study subject. Statistical significance was inferred at p < 0.05.
There were 389 preschool children aged 6-71 months who participated in the study. Their mean age was 32.7 months (SE + 0.81) (95% CI 31.1 to 34.2). There were 217 males and 172 females. Only 41 children (10.5%) had caries. The pattern and age related distribution of dental caries diagnosed in the study population is presented in Table 1. Nineteen (4.8%) children had rampant caries, 22 (5.5%) had caries, 355 (89.2%) had no caries, while two (0.5%) children had no teeth.
Maxillary and mandibular caries involved central and lateral incisors, and the first and second molars. The canines were spared. Distribution of types of carious lesions on molar teeth is shown in Table 2.
The 41 children had 57 carious primary molars. There were more mandibular molar caries compared with maxillary molar caries (41 vs 16); for the maxillary molars, there were 10 (62.5%) teeth that had occlusal surface caries only, 5 (31.3%) carious teeth involved one proximal surface and one (6.2%) tooth with two proximal surface involvement. In the mandible, 29 (70.7%) teeth had occlusal caries, 11 (26.8%) teeth had caries involving one proximal surface and 1 (2.4%) tooth with two proximal surface involvement. There was however no significant difference in the prevalence of these lesions (occlusal vs proximal) with respect to location (p=0.55).
Of the posterior carious lesions 29 were on the first molars and 28 on the second molars. There were 10 (34.5%) carious maxillary first molars; and 19 (65.5%) mandibular first molars; 6 (21.6%) maxillary second molars; and 22 (78.5%) mandibular second molars. There were significantly more lesions on the second mandibular molars than on the second maxillary molars with the odds ratio of having a second mandibular molar carious being 4 times more than having a second maxillary molar carious (95% CI 1.8 to 11.8) p=0.0009.
These children also had 47 carious anterior teeth with more carious lesions in the maxilla than in the mandible (41 vs 6). In the maxilla, five (12.2%) teeth were badly broken down, 14 (34.1%) had buccal surface caries and 22 (53.7%) had proximal caries. In the mandible, two (33.3%) teeth were badly broken down and four (66.7%) teeth had proximal caries. The odds of having an maxillary incisal caries was 8 times more in comparison to having mandibular incisal caries (95% CI 3.7 - 20.8) p<0.001.
There was no statistically significant difference in the pattern of caries presentation and the age of the patient except for the lesions on the maxillary right central incisor (p=0.002). The risk for caries on the buccal surface of the maxillary right central incisor increased by 1.71 (95% CI -2.7 to -0.71) p=0.001 for every year decrease in age.
A summary of the children's OH practice and status is shown in Table 3. A majority (77.5%) of the children had good OH. More than half (51.43%) of the children used a toothbrush and paste, while 5% did not clean their teeth at all.
The gender, birth rank, socio-economic status, tooth cleaning tool and tooth cleansing frequency had no impact on the dmft of the child but the age and OH status did: for every month increase in the age of the child, the dmft increased significantly by 0.01 (95% CI 0.005 to 0.017) p<0.001. Also for every score increase in the OH assessment, the dmft increased by 0.22 (95% CI 0.11 to 0.33) p<0.001. However, on linear regression, the effect of OH status on the dmft was lost after adjusting for the possible effect of age.
The OH status was the only significant risk factors for rampant caries with the odds ratio of having rampant caries increasing over 2 fold (2.58) with every score increase in OH status (95% CI 1.03 to 6.46) p=0.04 after adjusting for age, gender, socioeconomic status, tooth cleansing tool and tooth cleansing frequency. The model could predict about 19% rampant caries risk (R2= 0.19). The OH status was not a risk factor for caries (p=0.319) and for not having caries (p=0.16) within the defined model.
The first primary molars in both the mandibular and maxillary arches are much less susceptible to caries on their occlusal surfaces than the second primary molars, even though the first primary molars erupt earlier. This present study also observed this. This difference in caries susceptibility is no doubt related to differences in morphology of the occlusal surface. The second primary molar usually has deeper, less completely coalesced pits and fissures [McDonald and Avery, 2000]. Curzon , however, reported that while occlusal lesions in the primary molars are more common than interproximal lesions in the preschool children initially, once the posterior contacts close after three years, interproximal lesions increase. This present study, nevertheless, could not establish an age-related prevalence in the occurrence of occlusal versus proximal caries except for the case of the maxillary right central incisor. The authors cannot readily explain this observation and this may have been a chance finding. The inability of this study to establish a relationship between age and dental caries may be due to the limitation of the study design: the study was not a longitudinal one which might otherwise have measured the incidence of caries in relation to age rather than the current measure of caries prevalence in relation to age. Also, the study did not use radiographs to determine the presence of proximal caries. This is a limitation to the interpretations that that can be given to the outcome observed in this study.
Past studies [Raadal and Espelid, 1992; Anderson et al, 2005] established that about 33%-55% more approximal caries could be detected using a bitewing examination even in low caries prevalent areas. The observation in this study can therefore be limited to observations made during clinical examination only.
Increased frequency and better OH levels have been associated with lower caries levels in pre-school children [Correa et al., 1996; Vanobbergen et al., 2001]. In addition, Freeman et al.,  stressed that participation and help by parents are essential components in a pre-school child's OH. This study was not able to establish an association between the dmft, an outcome measure for caries, and the OH status, frequency of tooth brushing and tools used for tooth cleansing after adjusting for age, gender, birth rank and the socioeconomic status of the child.
With respect to specific caries pattern, OH status was found to be a highly significant risk factor for the diagnosis of rampant caries. The reported association between rampant caries and OH status in this study had been previously reported. Raesine and Douglass  noted that the lesion starts on surfaces that can be easily accessed by routine tooth brushing. Also, further evidence shows that OH played a modulating effect on the risk for rampant caries in the presence of sugar with children who have poor OH and have frequent contact of sugary diet on maxillary anterior teeth having a high risk for caries [Vacca-Smith and Bowen, 1995]. This study is limited in establishing the relationship between OH, frequency of sugar consumption and rampant caries as no data was collected with respect to sugar consumption.
There appears to be no significant age-related caries distribution pattern based on clinical examination only in Nigerian preschool children: rampant caries or simple caries prevalence does not appear to be age dependent. The second molars appear to be more susceptible to caries in preschool children in Nigeria. The oral hygiene status was felt to be a risk factor for rampant caries in these children.
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A. Sowole, Lagos State University Teaching Hospital, Ikeja,
E. Sote, Dept. Child Dental Health, University of Lagos, Lagos;
M. Folayan, Dept.Child Dental Health, Obafemi Awolowo University, Ile-Ife, Nigeria
Postal address: Dr. A. Sowole, Lagos State University Teaching Hospital, Ikeja, Lagos, Nigeria.
Table 1. Pattern of severity of dental caries in a pre-school Nigerian child population. Age Rampant Caries Distribution Caries Caries free > 12 0 0 22 months 13-24 4 1 138 months 25-36 8 2 69 months 37-48 1 7 62 months 49-71 6 12 55 months Total 19 22 346 * 2 children had no erupted teeth Table 2. Distribution of carious on molars teeth in a pre-school Nigerian child population. Caries Maxilla Mandible Total (%) N (%) N (%) Occlusal 10 (62.5) 29 (70.7) 39 (68.4) Proximal 6 (37.5) 12 (29.3) 18 (31.6) Total 16 (100.0) 41 (100.0) 57 (100.0) Table 3. Distribution of oral hygiene status and practice of children in a pre-school Nigerian child population. Oral hygiene Number status 1 Good 276 (77.53%) 2 Fair 37 (10.39%) 3 Poor 38 (10.37%) Total 356 (100.00%) Tooth cleansing tools 1 Nothing 18 (4.68%) 2 Cotton wool 121 (31.43%) 3 Foam 37 (9.61%) 4 Toothbrush 198 (51.43%) 5 Hand towel 11 (2.86%) Total 385 (100.00%) Frequency: brushing per day 1 None 19 (5.01%) 2 Once per day 269 (70.98%) 3 Twice per day 86 (22.69%) 4 Thrice per day 5 (1.32%) Total 379 (100.00%)
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