Simultaneous Non-Invasive Diagnosis and Therapeutic Treatment of Dental Caries
112333141
Layra Valdes , Juaana Xie , Ellen Yaacoub , Masahiko Maeno , Yoshiki Ishida , Hiroshi Ishikawa , Hiroe Ohyama , Jirun Sun , Shigemi Nagai

1: Harvard School of Dental Medicine, 2: International University Of Catalonia-Barcelona, 3: The Nippon Dental University, 4: ADA Forsyth Institute.

Introduction and Goal
Early diagnosis and treatment are vital for managing dental caries, a widespread chronic disease. Previousstudies using OsteoSense (OS750) and etidronate showed promise in diagnosing and treating caries bypromoting remineralization. Challenges like tooth autofluorescence and dye agglomeration arose. Our
research aims to combine the benefits of OS750 and etidronate using Eti-BPP-QDs, utilizing surfacefunctionalized Ag2S quantum dots dispersed in etidronate solutions. BPP-QDs offer adjustable emission
wavelengths, minimizing tooth autofluorescence with long-wavelength emission (> 900 nm) and enabling
detection of advanced and incipient caries missed by radiographs. Moreover, BPP-QDs exhibit higher
quantum yield and longer fluorescence life compared to OS750, enhancing sensitivity in caries diagnosis. The
goal is to develop a novel dental varnish that detects and inhibits caries progression through a combination ofbisphosphonate and quantum dots, enabling non-invasive optical diagnostic imaging with NIR fluorescence
QDs emitting beyond the tooth autofluorescence region.

Aims and Methods
Aim 1: To detect dental caries using NIR fluorescence imaging with Eti-BPP-QDs
created at Forsyth. Our diagnosis method involves ex vivo assessment using NIR
Camera (Digital VIS-SWIR Camera, Ninox 1280). Human teeth were assembled in atypodont, created artificial caries lesion on occlusal and interproximal l surfaces. TheD90/D45 optical geometry was used to capture fluorescence signal from lesions.
Specificity and sensitivity were determined by comparing FL signals to bitewing
radiography, considered the gold standard.
Aim 2: To assess the therapeutic efficacy of Eti-BPP-QDs to enamel and dentin caries. The therapeutic
performance of the Eti-BPP-QDs on inhibiting caries progression of enamel and dentin caries was determined
and compared to commercial fluoride varnish. The white-spot lesions were created on enamel and dentinspecimens. Each specimen was treated by Eti-BPP-QDs, fluoride varnish or distilled water. The micro CT was
taken before and after 2 cycles of demineralization challenges. The volume of each sample was measured andpercentage of volume remained after 2 cycles of demineralization challenges was calculated.

Aim 3: To assess the impact of BPP treatment on tooth aesthetic and tooth structure.
Aim 3-1. We assessed the tooth color changes on enamel and dentin surface (n=4, human extracted teeth)
treated by Eti-BPP-QDs and SDF using dental spectrophotometer (Crystaleye).
Aim 3-2. The adhesives’ bonding strength of composite block on the Eti-BPP-QDs treated enamel surface (2minuets) and non-treated enamel surface (control) were compared. A vertical cut was made horizontally to thetooth axis to divide it into mesio-distal areas, and the mesial area was used as the experimental tooth surface
and the distal area was used as the control tooth surface. The specimens were etched (40 seconds), washed,dried and Eti-BPP-QDs was applied for 2 minutes. Both experimental and control tooth surfaces were bondedwith resin composite block (Cleafil AP-X) with Clearfil SE bond 2(adhesive). Specimens were stored in distilledwater at 37℃ for 24 hours. The micro tensile adhesive strength was measured using the Instron machine (n=6).

Results
Aim 1. Accuracy of caries detection
Using geometry-D90/D45, fluorescence signal on the interproximal demineralized
lesion was clearly detected (Figure 1). Diagnostic accuracy by 3 experienced
restorative dentists indicated high specificity and sensitivity (Table 1).
Table 1: Diagnostic accuracy.

Aim 2. Therapeutic efficacy
The caries progression was seen after each of 2 treatment.
Figure 2 shows micro CT images and reconstructed 3D
images before and after 2 demineralization challenges. The
lesion depth increased significantly. Average of percentage
of volume remained after 2 challenge cycles on specimens
treated by both NaF and Eti-BPP-QD was higher thancontrol for enamel and dentin, but there was no significant
difference (Figure 3, One way ANOVA)- Before -DMD

Sensitivity

Specificity123

0.93
0.93
0.9111- Enamel -- After -Figure 2: Micro CT and reconstructed 3D images before and after 2 demineralization cycles.

Figure 1: NIR images on caries
True
Positive
111False
Positive000

True
Negative
0.9
0.9
0.857

False
Negative
0.1
0.1
0.143

- Dentin -Figure 3: Average of percentage of volume remained after 2
challenge cycles in enamel and dentin group.

Aim 3-1. Color stability
The average CIE color difference dE values are shown in figure 4. .2 ± 1.4
for control group. At 10 days, SDF groups indicated significantly larger dEthan Eti-BPP-QD groups that dE values are clinically indistinguishable.

SDF

Eti-BPP-QD

Aim 3-2. Bonding strength
The average bonding strength of Eti-BPP-QD group was 21.6 ± 3.3 and 22.2
± 1.4 for control group. There was no statistical difference (Student t-test).

Conclusion
This study indicates a potential on clinical application for diagnostic and therapeutic treatment using Eti-BPP-QDs.
There is a need of further investigations for therapeutic efficacy in mimicking in vivo condition.

References• Sun, J.; Gil, M.; Khorashadi, S.; Chen, G.; Lee, C.; Ishida, Y.; Nagai, M.; Wada, S.; Ishikawa-Nagai, S.; Da Silva, J. D., Efficacy of bisphosphonates in detection of early enamel caries using NIR fluorescence imaging and inhibition of caries progression. International Journal of Medical Sciences 2021, 18 (13), 2971-2980.
• Gonzalez-Bonet, A.; Kaufman, G.; Yang, Y.; Wong, C.; Jackson, A.; Huyang, G.; Bowen, R.; Sun, J., Preparation of dental resins resistant to enzymatic and hydrolytic degradation in oral environments. Biomacromolecules 2015, 16, 3381-88.