Prevalence, characteristics, and severity of oral impacts
The prevalence of oral impacts experienced by the participants of the study during the past three months was 47.0%. That is, 132 out of 281 participants reported at least one or more impacts. The prevalence reported in the current study is lower than the other studies on similar age groups that used the same tool (Child-OIDP). The Thai study  showed that the prevalence of oral impacts was 89.8%; the Brazilian study  showed that the prevalence was 80.7%; the French study  showed that the prevalence was 73%; the Malay study  showed that prevalence was 66.7%; the Ugandan study  showed that the prevalence was 62% and the Sudanese study  showed that the overall prevalence was 54.6%. Differences in the severity of disease, cultural variations, age differences, and location of the participants may partly explain the reasons for the differences in the overall impact in different studies. In the present study, face validity was conducted even though the Child-OIDP is a standard validated questionnaire. This is because Fiji is ethically very diverse and it was essential to determine if the tool was understood by the participants.
There were other studies where the prevalence of the overall oral impacts were lower than in the current study: 8.6% in the Tanzanian study , 30.0% in the Spanish study , and 40.4% in the English study . This implies that either the prevalence of oral conditions/diseases is low in these studies or the participants’ QoL is not affected by the burden of oral diseases or both.
The mean Child-OIDP score for the current study was 2.2 ± 5.0, which is more than those reported in other studies. For instance, in the Sudan study  the Child-OIDP score was 1.4 ± 1.7 and in the Italy study  the score was 1.9 ± 3.7. However, the mean Child-OIDP in the current study was much lower in comparison to most studies that used the same tool and looked at similar age groups. One of the reasons for the low Child-OIDP values in the current study may be because the participants’ may not perceive that the oral conditions/diseases have an impact on their QoL. For instance, in the Thailand study  the Child-OIDP score was 7.8 ± 7.8, in the France study  the score was 6.3 ± 8.2, and in the Brazil study  the score was 9.2 ± 10.1.
Among the participants with impacts, the range of impacts varied from one to eight PWI. This result is similar to the findings of other studies done in other settings using the same tools, such as in Sudan , Thailand , England , Brazil  and Malaysia . In the current study, 54.5% of the participants reported at least one PWI, 17.4% had two PWI, 17.4% had three PWI, and 6.1% had four PWI. Few participants had five or more PWIs, 4.6%.
Even though the overall prevalence of impacts in the current study was lower than most studies mentioned above, the individual performances with impacts was higher in the current study. In the Thai study , about 16.2% of the participants had at least one PWI, in the Sudan study  it was 18.1%, and in the England study  it was 40.4%. On the other hand, there were some studies where the individual performances with impacts were higher than in the current study, such as the Malaysia study  where it was 66.7% and Brazil  study where it was 80.7%. In the current study few participants had severe or very severe intensity of impacts the findings were very similar to the findings from the Thai study .
Despite the findings of the study showing that oral impacts are prevalent in this current study population, they were not reported to be severe. Most of the clinical causes that added to the prevalent impacts are self-limiting, for instance oral ulcers. The current study reported that eating was the most significant aspect of oral health-related quality of life of the participants.
In relation to the most prevalent oral impacts, eating and relaxing were the two performances that were mostly affected in the current study; however, the intensity of the impact was not severe. The performances on which the intensity of impact was most severe were study and contact, and these two performances were the least prevalent. These three performances, eating, speech and cleaning had low levels of severe and very severe intensity of impacts. The findings of the current study were similar to those reported in other studies. Eating was the most prevalent performance that had the highest reported impacts in other studies [6, 13, 19,20,21,22, 24,25,26,27] as well. Other prevalent performances with impacts were emotional status in certain studies [13, 20], and cleaning, as shown in other studies [6, 19, 22, 24,25,26,27].
Causes of oral impacts
The participants perceived several oral and dental problems as the causes that had impacts on their general oral health. The problems that were reported to be most prevalent and led to oral impacts were dental sensitivity, dental caries, toothache and bleeding gums. This finding was consistent with other studies [13, 20, 25,26,27]. Other studies reported of other perceived dental problems as more prevalent, such as badly positioned teeth ; toothache [24, 27]; and erupting teeth .
Additionally, oral conditions associated to appearance and gums frequently affected the participants, modified (unpleasant) color of teeth, swollen gums and bad breath (10.8%) were quite frequently cited. These findings were not reported in many studies; however, they were consistent with two of the other studies [21, 27].
Although this is the first study conducted in Fiji there were a few limitations such as one of the schools that were selected was an all-girls school and this tipped the balance of gender in the study towards female participants. Due to this limitation gender-based analysis and reporting was not done in this study. The data from the questionnaire is self-reported. As much as self-reported data provides useful information, there is always possibilities of selective memory (participants may or may not recall the events that occurred have few months ago); telescoping (recalling events that occurred at one time as if they occurred at another time), in the study the period of interest was 3 months; possible bias might have been incorporated if the participants recalled events that would have occurred more than three months ago. Attributions may have led to over or underreporting of both negative and positive aspects. Exaggeration (the act of representing outcomes or events as more significant than in reality), this could have led to reporting disease as more severe than it was. The inclusion of questions related to socio-economic status in the questionnaire would have given more scope for analysis and comparison of oral health-related quality of life to social indicators. The Spearman’s correlation between some domains were low; the possible reasons for this could be variability in data, lack of linearity, presence of outliers, errors in measurement and characteristics of the sample. This is expected when samples are selected from a diverse population pool. A post-hoc analysis was not done in this study, however, this would be provided useful insights and is recommended for future research. Even though the original version of the Child-OIDP has shown acceptable internal consistency when used directly in the Fiji setting, concurrent validity tests would be useful to validate this index and is recommended for future studies. It is also recommended that the test–retest reliability of the Child-OIDP questionnaire is carried out in future studies to fully evaluate psychometric properties of the tool in the Fijian context.
The general implications of this research are that it was able to fill the gap in knowledge and provide baseline information regarding OHRQoL in adolescents in Suva, Fiji. It was also able to provide a clear picture of the burden of the two most common oral diseases, dental caries and periodontal disease, in 15-year-olds in Suva, Fiji. With this information at hand, it was easier to answer the question regarding the effects of oral diseases/conditions on QoL.