Aims: This study aimed to determine the effect of fluorine in dentin remineralization. Guided tissue remineralization has been shown to remineralize affected dentin by forming intrafibrillar and extrafibrillar minerals. Through polymer-induced liquid precursor system, crystals are formed with small sizes and occur intrafibrillarly. The addition of fluorine can form larger fluoroapatite crystals and complete the remineralization to the extrafibrillar. Existing research only focuses on the dentine surface, while there has been no research to prove remineralization in the dentine tubular walls. Objectives: The objective of this study was to determine the effect of adding 5ppm and 25ppm fluorine in the polymer-induced liquid precursor system on topographical changes and the percentage of fluoroapatite of the dentinal tubule walls. Methods: Demineralized dentin blocks were immersed in 5ppm and 25ppm fluorine remineralization solution. Dentine blocks were cross-sectioned using fracture method and analyzed using field emission – scanning electron microscope, and x-ray diffraction. Results: Topographical changes occurred on the dentinal tubule walls after remineralization with the addition of 5ppm and 25ppm fluorine through field emission scanning electron microscope test. Statistical tests were performed using SPSS 25 (SPSS inc) software to analyze the X-ray diffraction data. X-ray diffraction analysis showed that there was no statistically significant difference between the addition of fluorine to the percentage of fluoroapatite mineral phase, but substantially there was an increase in the percentage of fluorapatite. Conclusion: The addition of fluorine in the polymer-induced liquid precursor system does not influence changes in the topography of the dentinal tubule walls and the percentage of fluoroapatite. © 2024 The Author(s). Published by Bentham Open.