Dental caries and gingivitis by tooth type among 13-15 Year-olds with varying severity of fluorosis

Abstract

Background: Dental caries is a significant oral public health concern globally. Studies have demonstrated an association between dental caries and dental fluorosis but there is scarcity of data on dental caries and gingivitis in relation to severity of fluorosis by tooth type.

Objective: To determine dental caries experience and gingivitis by tooth type among 13-15 year-olds with varying degrees of severity of dental fluorosis ..

Materials and Method: This was a descriptive cross-sectional study which was conducted in public primary schools within Ngong and Rongai divisions of Kajiado North District, in the Rift Valley Province in Kenya. A simple sampling procedure was used to identify the schools and stratified sampling for the study participants" A total of 455 children aged 13-15 years old (mean age was 13.6 years) who met the inclusion criteria, filled a self-administered questionnaire on demographic data, source of water for domestic use and oral hygiene practices. Water samples from the water sources was analysed for fluoride levels using the colorimetric method. A clinical examination under natural light using a dental mirror and probe was carried out for plaque accumulation using Silness-Loe (1964) plaque index, and DMFT Index was used for dental caries. Dental fluorosis was assessed using the Thylstrup and Fejerskov Index (TFI) score, and gingival inflammation was diagnosed using Loe-Silness Gingival index.

Statistical analysis was performed using Statistical package for Social

Sciences (SPSS version 17.0). Pearson's Chi-square test was used to

xv

determine association between categorical variables, the level of statistical significance was at a confidence interval of 95%, and p s 0.05.

Results: Out of the 455 children selected for the study 240(52.7%) were 13 years old, 148(32.5%) were 14 years old, 67(14.7%) were 15 years old. One hundred and seventy seven (38.9%) brushed their teeth once a day, 230 (50.5%) twice a day, both in the morning and night after meals. Twenty two (4.8%) of them did not brush everyday while 26(5.7%) never brushed their teeth. A majority of the teeth (31.9%) examined had a plaque score of 2.The maxillary first molar had more teeth with a plaque score of 3 compared to the other teeth which were examined. The relation between plaque accumulation and severity of fluorosis was statistically significant on four of the tooth types examined (maxillary right first permanent molar, maxillary right lateral incisor, maxillary left lateral incisor and mandibular left lateral incisor) using the Chi square test.

The prevalence of gingivitis was 59.6% among the participants. Based on the tooth surfaces which were examined it was observed that there was an association between gingivitis and dental fluorosis, it was statistically significant on the maxillary lateral incisor with a p=0.03, (psO.05). While in the s:

mandibular 1st premolar the gingivitis in relation to the severity of dental fluorosis was found to be statistically significant with a p=0.02, (psO.05).

Spring water had a fluoride level of 0.44mg/l, river water had a level of

1.6mg/1and bore holes' had a range of 0.1 - 10mg/1. A test for association between water source and TFI score using fishers exact formula was not statistically significant (Chi value 8.01; p value = 0.75)

xvi

The prevalence of fluorosis was found to be 66.6%. the prevalence according to specific tooth type was CI and U- 64.4%, canine- 64.3% PM-1- 63.6%, PM-2-63.2%. The first and second permanent molars each had a prevalence of 63.6% and 63.2% respectively. The prevalence of dental caries among the participants was 14.8% with a mean DMFT of 0.40 SD±1.28. The number of decayed teeth increased with the severity of fluorosis for all tooth types. However there was no statistically significant relation between the severity of dental fluorosis and DMFT on the lateral incisor and the canine with a p=0.071 and p=0.262 (p~0.05) respectively.

Conclusion: There were statistically significant associations between gingivitis on some tooth types in relation with varying degrees of severity of dental fluorosis. However there was no association between the mean DMFT by tooth type and the severity of dental fluorosis by tooth type.

Recommendation: Further studies are recommended to include the dietary habits of the children, as certain micronutrients like calcium have been shown to reduce the effect of high levels of fluoride on developing teeth by reducing the absorption of fluoride from the gastrointestinal tract, and also, to identify if there were protective factors against dental caries. 4

There is need for preventive oral health services through the school based programmes to create oral health awareness in the population and provision of curative services for those children who are affected by dental fluorosis. Defluoridation of the water sources which have fluoride levels higher than the recommended levels should be done.