Friday, 20 June 2014

Assessment of Enamel Demineralisation and Remineralisation using Terahertz Pulsed Imaging

D. CHURCHLEY1, F. LIPPERT2, A. BUTLER1, A. PORTIERI3, and R.J.M. LYNCH11GlaxoSmithKline Consumer Healthcare, Weybridge, England, 2Indiana University School of Dentistry, Indianapolis, IN, 3TeraView Ltd, Cambridge, England


Objective
Transverse micro-radiography (TMR) is the “gold standard” for measuring mineral changes in enamel; however, it is destructive in nature. The aim of this study was to compare Terahertz Pulsed Imaging (TPI), a non-destructive technique, with TMR for measuring mineral changes in enamel.

Methods 
Lesions with diverse mineral characteristics were created in bovine and human enamel blocks (n=48 per enamel type) using three demineralising systems (MeC, Carbopol C907 & HEC).  Specimens were assigned to two treatment groups (n=24 per enamel type per group): Group 1: remineralisation for 5 days (1.5mM CaCl2.2H2O, 0.9mM KH2PO4, 20mM HEPES and 130mM KCl) Group 2: demineralisation for 2 days (50mM acetic acid, 2.25mM CaCl2.2H2O, 1.35mM KH2PO4, 130mM KCl and 5ppm F).  Lesions were imaged using a TPI imaga 1000. Reflection data were used to generate lesion mineral profiles.   Lesions were also radiographed.  For both techniques the integrated mineral loss (ΔZ), lesion depth (L), change in mineral content (ΔM), and change in lesion depth (ΔL) were calculated. Pearson correlation coefficients were calculated for the combined data set as well as by enamel type, treatment and lesion type.

Results
The table shows the Pearson correlation coefficients.  There is generally a good association (Pearson coefficients ≥ 0.70) between TPI and TMR measurements for most variables.


Variable
Combined
Enamel Type
Treatment
Lesion Type
Bovine
Human
Demin
Remin
MeC
C907
HEC
ΔZ(baseline)
0.66
0.69
0.65
0.59
0.81
0.28
0.74
0.47
ΔZ(post-treatment)
0.84
0.92
0.71
0.78
0.83
0.82
0.82
0.77
ΔM
0.75
0.84
0.58
0.55
0.52
0.80
0.72
0.70
L(baseline)
0.79
0.77
0.80
0.76
0.87
0.19
0.75
0.20
L(post-treatment)
0.88
0.95
0.77
0.75
0.73
0.97
0.87
0.78
ΔL
0.84
0.93
0.65
0.49
0.51
0.94
0.80
0.82

Conclusion 
Whilst these initial findings demonstrate that TPI could be a useful technique for the non-destructive assessment of enamel mineral changes; further evaluation is required.

This study was performed using TeraView's Imaga 1000 system (TeraView, Cambridge, UK) 

Full Article: https://iadr.confex.com/iadr/14iags/webprogram/Paper189313.html