Dental caries is one of the most common chronic diseases worldwide, affecting billions of people across all age groups. Globally, an estimated 2 billion individuals suffer from caries in permanent teeth, while approximately 514 million children are affected in their primary dentition [1]. This significant global burden reflects the persistent challenges related to oral hygiene practices, dietary patterns, and access to preventive dental care. In Laos, several studies have reported a high prevalence of dental caries among children aged 3–15 years. Previous research indicates that the prevalence reaches 95.87% in primary teeth and 86.13% in permanent teeth among school-aged children [2]. Similarly, a study conducted in 2010 showed that 82% of Lao children aged 3–5 years had primary tooth decay, with a mean dmft score of 5.5 [3]. Another investigation in 2013 revealed a prevalence of 93.6% for dental caries in permanent teeth [4]. These findings collectively demonstrate a substantial oral health challenge affecting Lao children across different age groups. The World Health Organization (WHO) has emphasized the importance of improving oral health at both community and population levels, recognizing childhood caries as a significant public health concern requiring urgent attention. Despite multiple individual reports, there is considerable variability in the reported prevalence of dental caries across different regions of Laos. Moreover, to date, no systematic review has comprehensively synthesized the available evidence on dental caries in the Lao population. Therefore, this systematic review and meta-analysis were undertaken to estimate the overall prevalence of dental caries in Laos by analyzing published data from 2002 to 2024. By consolidating existing findings, this review aims to provide a clearer understanding of the caries burden in the country and to support future oral health policymaking and intervention strategies.

1. Aims and objective

Participants from the age 3 – 15 years from different part of Laos were covered in this meta-analysis of 11 studies

• Methodology

This systematic review was designed to be as a comprehensive followed the PRISMA guideline ⁽⁵⁾. The searched database included PubMed, web science, Scopus, Google scholar search strategy for each database by using key worlds to exact data, with free- text words. Study focused of review to determine the prevalence of Dental caries with mean of dmft and DMFT in children 3- to 15-year-old in Laos

Included Criteria

The eligibility criteria, there are any type of observational study design was evaluated in this review such as  the prevalence of participants  from  3  to 15 years old by using dmft, DMFT,WHO pro forma 1997, PUFA, by cross-sectional study, case control, prospective and  retrospective  study .Studies has to be published on 2002 until 2024.

Exclusion criteria

Studies were excluded if the data measured the incidence of other oral conditions, and did not consider dental caries , and no mention of dfmt/ DMFT with SD detail. studies written in other language were excluded.

Data collection process

Identified studies were collected and checked by the three reviewers. The studies found total 1780 that include  from PubMed, and  web sciences, the Endnote X7 was used for check the duplicate, with 1735 studies were removed. 45 with full text read studies were further screen, and 29  studies were  reported for age interval than 3 to 15 years Studies  and mention with special needs for treatment. 16 Full text articles were  eligibility, 4 Non availability of  standard deviation of dmft/ DMFT score and not  availability of average dmft/DMFT scores. Finally, 12 studies were suitable for satisfy of this meta-analysis (Fig.1)

Data analysis

The statistical program  Meta-Essentials  software ⁽⁶⁾  was used for analysis. The meta-analysis using Random

 effect or fixed effect model. If heterogeneity was present, then the random effect model was used. The fixed effect was used when the heterogeneity was absence. Forest plots were used for demonstrated the effect of each study.

 The investigate publication bias were constructed by funnel plot and Egger’s test for small study effect  was performed to assess the degree of asymmetry by P<0.05 was considered as significant.

Data extraction

The details of information were  extracted  from those publications, the data of  tooth decay were separating by primary and permanent teeth in the table (table 1) and (table 2). Eight articles included both primary and permanent teeth (Sun-Gil Park  et al,2023,  Yong soo  Park et al,2023, Dong-Hyeon Kim  et al, 2023, Jae-Geun Ka et al,2019,Sjobbe Besseling   et al, 2013,Nithasack  Phommavongsa  et al, 2014, Nithasack  Phommavongsa  et al, 2015, Nithasack  Phommavongsa  et al, 2016) ^{(2) ,(7), (8), (9), (4) , (10)} , while only two study reported caries in primary teeth (  Sakpaseuth  S et al, 2010, Homsavath et al, 2024) ^(3),(11), and two articles reported caries in permanent teeth(Gisela Ladda Tayanin  et al, 2002, Nanna Jurgensen et al, 2009) ^{(12), (13)}                 

Primary Teeth

Seventeen studies reported caries in primary teeth and were included in the meta-analysis. The total combined sample size was 2,465 participants. Across these studies, the overall prevalence of caries in primary teeth was 98.3%, with reported values ranging from 82% to 95.87%. A heterogeneity assessment was performed prior to constructing the forest plot. The heterogeneity test showed P = 0.02 and an I² value of 43.58%, indicating moderate and statistically significant heterogeneity. Therefore, a random-effects model was applied to estimate the pooled prevalence (Fig. 2). The pooled mean dmft score for primary teeth in children aged 3–8 years was 5.76 with a 95% confidence interval (CI: 2.55–14.06). A funnel plot was generated to assess publication bias (Fig. 3). Visual inspection revealed a relatively symmetrical distribution of data points, suggesting the presence of publication bias. Egger’s regression test was further used to evaluate funnel plot asymmetry, and the result indicated P < 0.01, confirming significant publication bias.

Permanent Teeth

Thirty-six studies reporting dental caries in permanent teeth were included in the meta-analysis. The total sample size across these studies was 3,747 participants. The proportion of individuals with caries in permanent teeth showed an average prevalence of 44.8%, with reported values ranging from 35.3% to 93.6%. A heterogeneity test was performed prior to constructing the forest plot. The results indicated P = 0.11 and an I² value of 23.11%, demonstrating low and statistically insignificant heterogeneity. Therefore, a fixed-effects model was applied to calculate the pooled prevalence (Fig. 4). The pooled mean DMFT score for permanent teeth among children aged 6–15 years was 1.31, with a 95% confidence interval (CI: 1.66–4.27). A funnel plot was also generated to evaluate publication bias (Fig. 5). The distribution of data points suggested potential publication bias. Egger’s regression test was applied to assess funnel plot symmetry, yielding P < 0.01, confirming the presence of significant publication bias.

• Discussion

This study aimed to systemic review studies to evaluating the prevalence of dental caries in Laos from 2002 to 2024.  There were identified 12 studies, as well as  for primary and permanent and mixed dentition separate in to two groups,  this systematic review and  meta-analysis  set out  to evaluated of the combined variance prevalence of  dental caries in Lao population.  In 1999 the fluoride concentration in the drinking waters has been estimated in some provinces of Lao People’s Democratic Republic, however the drinking water fluoride has low concentration was 0.0 and 0.5ppm in some place in Laos ⁽¹⁴⁾, even though the oral health program such as toothbrush education, fluoride mouth rinsing program, fluoride topical application, and sealand  in primary school were provide  ⁽¹⁵⁾. Most of studies on dental caries were high in various geographical area.  

The present study  in 3 – 15 years with 98.3% under 6 years and 44.8% in patients above 6 years, this finding is congruence with result of the study in 2019 was reported that the prevalence of dental caries with 82%  among 1161 student 6-10 years in Vientiane   ⁽¹⁶⁾  , similarly  in the India 2005 among  children 5-7 years old⁽¹⁷⁾, the decayed primarly teeth index was 94.30%, and  studied in 2014 among 12 and 15 year the prevalence of permanent  teeth in  47.80 and 44%(18). With high percentage of dental caries in children with untreated dental caries in primary dentition was significantly highest in underweight children ⁽¹⁹⁾. The included of this present review showed  of heterogeneity I²  =43.58  and   23.11  for primary teeth and permanent teeth, respectively, With proportion 5.76    ( 2.55 – 14.06 )and 1.31 ( 1.66 – 4.27) Heterogeneity index had  significant  in outcome of dmft and DMFT, this more higher than reported  in Saudi children 2023 with dmft  index 4.14 (3.11-5.18) and permanent teeth  was lower with DMFT1.28(0.93-1.64)⁽²⁰⁾  

 The strength of current review is the low heterogeneity between the studies include for analysis. However, there were some limitations  such as some of them did not mention age groups of participants , number of articles was limited , reported with this  mention limitations, future  studies   should focus on factors correlate with prevention  and need for nation  level  base for  equal representative of urban and rural of  whole country

• Conclusion

The average score of dmft/DMFT in primary and permanent teeth , the carie proportion 5.76  rang from2.55  to 14.06  and  1.31  from  1.66  to 4.27 for primary teeth and permanent teeth. This indicates that the prevalence of dental caries in Laos is high, however, the current data do not provide all dental caries in whole  of Laos.  This study indicated  to measure of prevention should be strategies  to reduce prevalence  of dental caries for Lao population.

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