Remineralization and Anti-Caries Potential of a nano-Hydroxyapatite
Post-Brushing Dental Lotion®

3649

Bennett T. Amaechi, Dina Alshareif, Parveez AbdulAzees, Linda Okoye, Ariana Bagheri,Marina Shehata, Patrícia Lima, Azadeh Abdollahi, Parisa Kalkhorani, Veronica Evans
University of Texas Health Science Center at San Antonio, TX, USA

Objective
The aim of this randomized, double-blind,
two-arm crossover in situ study was toinvestigate whether nano-hydroxyapatite(nano-HAP)
dentallotion
appliedimmediately after tooth-brushing with nanoHAP
toothpasteenhancestheremineralization and caries prevention
efficacy of nano-HAP toothpastes.

Introduction

Double-blind, randomized, crossover, controlled clinical trial

Screening/Enrollment: Oral Examination (n = 50)

30 qualified subjects enrolled and each underwent 2 treatment phases (G1 and G2).

G1: nano-HAP dental lotion

1 week washout period

Phase 1: 4 weeks were comprised of two 2-week treatment periods
Subjects randomly assigned to G1 or G2First 2-weeks: sound enamel block❖ The natural caries protective and remineralizing effects of saliva is not only aslow process but obviously insufficient to protect individuals against caries andremineralize existing lesions without additional agents to enhance its effects.
❖ The presence of additional extrinsic sources of stabilized Ca2+ and PO4 3– ions
could augment the natural caries control potential of saliva by increasing
diffusion gradients favoring faster and deeper subsurface remineralization.1❖ The potential of nano-hydroxyapatite to inhibit tooth demineralization andpromote remineralization of the initial caries lesion is now well established withsupporting evidences.2❖ Nanoparticulate hydroxyapatite may act as a calcium and phosphate reservoir,
helping to maintain a topical state of supersaturation of these ions with respect
to enamel minerals.3❖ Deposition on the surface of the demineralized enamel might promote
remineralization of the enamel caries lesion.3❖ Use of a nanoHAP-containing toothpaste elevated calcium concentrations insaliva, and caused the remineralization of early caries lesions in an in situ
study.4,5❖ We envisaged that completing toothbrushing with nano-HAP dental lotion
would increase the bioavailable Ca2+ and PO4 3– ions in saliva, on teethsurfaces and oral environment, thus enhancing the known caries control
potential of nano-HAP toothpaste.
❖ The present study, therefore, evaluated the additional benefit, with respect tocaries prevention and remineralization, of a nano-HAP dental lotion used
immediately after toothbrushing with nano-HAP toothpaste.

G2: placebo dental lotion

Second 2-weeks: lesion-bearing block

1 week washout period

Phase 2: crossover (G1 and G2 subjects switched)

Demineralization/Remineralization assessment using TMR

One-sided t-test of one group mean was used for intragroup comparison(baseline vs post-test), while two-sided t-test of two independent means wasused to compare the two dental lotions.

Results
TMR examination showed no demineralization in sound enamel blocks
exposed to either of the dental lotions.
There were no incidences of adverse effects reported by subjects orascertained clinically.

Materials and Methods
This is a double-blind, randomized, crossover, single center, controlled in situ
study.
The primary outcomes to be examined were (1) the percentage remineralizationand lesion depth reduction measured relative to the baseline mineral loss andlesion depth for initial caries, and (2) the amount of mineral loss and lesion depth
for the sound enamel.
UT Health San Antonio IRB approval was obtained (protocol#: HSC20180416H).

Pairwise comparison (baseline vs. post-test) indicatedsignificant (p<0.0001) remineralization by the nano-HAP
toothpaste in both the nano-HAP and the placebo lotion groups

30 subjects, 18-60 years old with normal saliva flow rate, were recruited and theywent through the study as shown in the chart below•30 Human permanent molar teeth were used to prepare 60 sound enamel
blocks and 60 blocks bearing an artificially-produced initial caries lesion.

•4 tooth blocks from each tooth, each mounted in an in situ appliance (Figure2); 2 lesion-bearing blocks for remineralization enhancement assessment
and 2 sound blocks for demineralization inhibition assessment.

•Mineral loss (∆z; vol%.µm) and lesion depth (ld; µm) of the artificial lesions
were measured before and after intra-oral exposure with Transverse
microradiography (TMR).

Figure 2: San Antonio in situ model••

Treatment groups:•G1 (experimental arm): nano-HAP toothpaste + 5% nano-HAP
containing dental lotion.

•G2 (control comparator arm): nano-HAP toothpaste + placebo dentallotion.

Each subject underwent 2 study phases. In each phase, subjects brushed 2x
daily for 14 days using Nano-HAP toothpaste for 2 minutes, while wearing 2appliances (1 sound and 1 lesion-bearing enamel). However, after bedtime
brushing, subjects finished up with either nano-HAP or placebo dental lotion
as described below.

•After bedtime (night) brushing, following rinsing with water, subjects poured
one full portion of the dental lotion into their mouth, swished it around like adental rinse, and used the toothbrush to gently spread it all over their teeth,including the appliance. The lotion was left in place for 2 minutes, andthereafter rinsed lightly with 10 ml of water. Subjects did not eat or drink forat least 30 min after using dental lotion.

•Safety was monitored at all visits by examination of the oral cavity and perioral area, and subjects were screened for adverse events using aquestionnaire

1. The mean amount of remineralization was determined for each group by
intra-product comparison (pretest vs post-test) by t-tests.
2. The means of the lotion group and the placebo group were determined using
the two-sided t-test of two independent means.

References
1.
2.
3.
4.
5.

When compared against each other, there was a significantly(p<0.0001) greater percentage of remineralization with postbrushing application of nano-HAP lotion (58.42 ± 1.76) thanwhen placebo lotion was applied (37.72 ± 2.22).

Philip N. State of the Art Enamel Remineralization Systems: The Next Frontier in Caries Management. Caries Res 2019; 53: 284–295.
Amaechi B T, van Loveren C. Fluorides and non-fluoride remineralization systems. Monogr Oral Sci 2013; 23: 15–26.
Hannig M., Hannig C. (2012) Nanotechnology and Its Role in Caries Therapy. ADR 24, 53-57.
Schäfer F., Beasley T., Abraham P. (2009) In vivo delivery of fluoride and calcium from toothpaste containing 2% hydroxyapatite. Int
Dent J 59, 321-324.
Najibfard K., Ramalingam K., Chedjieu I., Amaechi B.T. (2011) Remineralization of Early Caries by Nano- Hydroxyapatite Dentifrice
Journal of Clinical Dentistry 22(05), 139-14.

Conclusions

Within the limitations of this study, it canbe concluded that:❖ The application of 5% nano-HAP
containing dental lotion following
toothbrushing with 5% nano-HAP
toothpaste enhances the efficacy ofnano-HAP toothpaste in remineralizing
initial caries lesions.
❖ Since the remineralizing efficacy ofsaliva is strictly dependent on theavailability of calcium and phosphateions, nano-HAP dental lotion may be amore effective for xerostomic patientswith diminished amounts of saliva.