Abstract

Dental caries is a widespread infectious disease influenced by bacterial activity, dietary factors, and host

susceptibility. Community water fluoridation has been a key public health measure for caries prevention,

particularly in children. The optimal fluoride concentration in drinking water (0.7 mg/L) balances caries

reduction with minimal fluorosis risk. This study assessed fluoride levels in drinking water and their

correlation with dental caries in primary school children in Gharyan, Libya. A cross-sectional study was

conducted on 350 children (aged 7–10 years) from urban and rural schools in Gharyan. Water samples from

five stores and one groundwater source were analyzed for fluoride concentration using an ion-selective

electrode. Dental caries was assessed using the dmft/DMFT index. Fluoride levels in water stores were

negligible (0.0–0.1 mg/L), while unfiltered groundwater exhibited high concentrations (6.0–7.0 mg/L),

exceeding WHO guidelines (1.5 mg/L). The low fluoride availability in most drinking sources suggests

limited caries-preventive effects from water fluoridation in this region. The study highlights insufficient

fluoride exposure in Gharyan’s public water supply, potentially contributing to higher caries prevalence.

Further research is needed to evaluate alternative fluoride delivery methods and assess groundwater safety

to optimize oral health outcomes.

Keywords. Fluoride Concentration, Drinking Water, Dental Caries, Primary School

Abstract 

Dental caries is a widespread infectious disease influenced by bacterial activity, dietary factors, and host 

susceptibility. Community water fluoridation has been a key public health measure for caries prevention, 

particularly in children. The optimal fluoride concentration in drinking water (0.7 mg/L) balances caries 

reduction with minimal fluorosis risk. This study assessed fluoride levels in drinking water and their 

correlation with dental caries in primary school children in Gharyan, Libya. A cross-sectional study was 

conducted on 350 children (aged 7–10 years) from urban and rural schools in Gharyan. Water samples from 

five stores and one groundwater source were analyzed for fluoride concentration using an ion-selective 

electrode. Dental caries was assessed using the dmft/DMFT index. Fluoride levels in water stores were 

negligible (0.0–0.1 mg/L), while unfiltered groundwater exhibited high concentrations (6.0–7.0 mg/L), 

exceeding WHO guidelines (1.5 mg/L). The low fluoride availability in most drinking sources suggests 

limited caries-preventive effects from water fluoridation in this region. The study highlights insufficient 

fluoride exposure in Gharyan’s public water supply, potentially contributing to higher caries prevalence. 

Further research is needed to evaluate alternative fluoride delivery methods and assess groundwater safety 

to optimize oral health outcomes.

Keywords. Fluoride Concentration, Drinking Water, Dental Caries, Primary School.

Abstract:

Aim of the study: The purpose of current study was to evaluate and compare the effect of different connector designs on the 

compressive strength of posterior inlay-retained fixed dental prostheses made from two different ceramic systems.

Materials and Methods: Twenty-eight inlay retained fixed partial denture (IRFPDs) were used to replace missing lower right first 

molar. According to the IRFPDs material (lithium disilicate ceramic and Zirconia), the specimens were divided into two main groups A 

and B (n=14). These groups were further subdivided into 2 sub-groups 1&2 (n=7) according to the connector designs used (round and 

sharp). The IRFPDs were manufactured using the hot press and CAD-CAM techniques respectively. All specimens were cemented using 

self-adhesive resin cement. Each specimen was placed on the test device, and compressive force was applied till the failure occurred. All 

the results obtained were statistically analyzed by two way ANOVA test and student t test (level of significance p < 0.05). 

Results: Revealed that the highest mean value of compressive strength was for round connector with zirconia IRFPDs. While the lowest 

value was for sharp connector with lithium disilicate IRFPDs.

Conclusions: Within the limitations of this in-Vitro study the following conclusion could be obtained; zirconia demonstrated high 

compressive strength than lithium disilicate. Despite the lithium disilicate possessed the lowest compressive strength values for both 

types of connector design. However these values were greater than the average occlusal force recorded in several studies.

Keywords: IRFPDs, Connector design, Fixed prosthesis, CAD/CAM, Zircoina, Lithium disilicate, Compressive strength.