Effect on Sucrose/Fluoride Variations for Enamel Demineralization using Microbial Caries-model

Objective: To compare the effect of sucrose and fluoride concentrations on surface characteristics of demineralized enamel developed by five species [Actinomyces naeslundii (ATCC 19039), Lactobacillus casei (ATCC 4646), Streptococcus mutans (ATCC 700610 – UA159), Streptococcus salivarius (ATCC 25975), Streptococcus sanguinis (ATCC BAA-1455)] using a microbial caries-model.

Method: Twenty-eight ground/polished 3x3x2mm human enamel blocks were equally divided into four groups. Differences between the groups were variations in the concentrations of Sucrose present on Tryptic Soy Broth and Fluoride (F) in Mineral Wash as follows: Group-1 (Sucrose: 3%/F: 0.50ppm), Group-2 (Sucrose: 5%/F: 0.50ppm), Group-3 (Sucrose: 3%/F: 0.75ppm) and Group-4 (Sucrose: 5%/F: 0.75ppm). Specimens were demineralized for five days. Before and after demineralization, measurements were obtained by Optical Reflectometry [Reflection (Amplitude, %)], Surface Profilometry [Roughness (Ra, µm)], and Quantitative Light-induced Fluorescence [QLF (fluorescence loss, %)] with dehydration. At baseline, the surface was hydrated. Fluorescence images were acquired at 1-second intervals for ten seconds. During image acquisition, specimens were dehydrated with continuous compressed air. Change in fluorescence radiance per second (DF_D) was obtained. After measurements, specimens were sectioned (100µm) and analyzed with Transverse Microradiography [TMR: lesion depth (LD: µm) and mineral loss (IML: vol%×µm)].

Result: Means and standard deviations of TMR, Reflection and Roughness (Table 1) and those of DF_D at each second (Table 2) are shown. There were no significant differences (p>0.05) for amplitude and Ra values of sound enamel among the groups. Groups-1 and 2 had larger TMR and DF_D values than Groups-3 and 4 (p<0.05). Groups-1 and 3 indicated larger amplitude values than Group-2 and Group-3 was larger than Group-4 (p<0.05). Group-2 presented larger Ra values than Groups-1, 3 and 4.  

Table 1:

	LD	IML	Reflection (Sound)	Reflection (Demineralized)	Roughness (Sound)	Roughness (Demineralized)
Group-1	71.3±3.8	2251.6±340.9	100.88±3.04	69.53±20.53	0.38±0.20	0.88±0.35
Group-2	70.1±11.4	2483.9±310.6	100.39±4.31	45.70±14.73	0.36±0.22	3.23±2.14
Group-3	48.6±10.6	1501.4±279.0	100.30±4.90	66.93±8.91	0.38±0.08	0.75±0.35
Group-4	48.7±2.5	1544.0±105.2	100.39±4.96	54.17±7.87	0.47±0.49	0.73±0.72

 Table 2:

	1s	2s	3s	4s	5s	6s	7s	8s	9s	10s
Group-1	6.4±1.6	4.3±1.3	2.9±0.9	2.3±0.6	1.9±0.5	1.6±0.4	1.4±0.3	1.2±0.3	1.1±0.3	1.0±0.2
Group-2	6.8±1.4	5.3±1.0	3.8±0.7	2.9±0.5	2.3±0.4	1.9±0.3	1.6±0.3	1.5±0.2	1.3±0.2	1.2±0.2
Group-3	4.7±1.6	2.8±0.8	1.7±0.5	1.3±0.3	1.1±0.3	0.9±0.2	0.8±0.2	0.7±0.2	0.6±0.2	0.6±0.1
Group-4	3.7±1.8	2.2±0.9	1.5±0.6	1.1±0.4	0.9±0.3	0.9±0.3	0.7±0.2	0.7±0.2	0.6±0.2	0.5±0.2

 Conclusion: This study suggested differences in surface characteristics of biofilm-demineralized enamel. Higher fluoride or lower sucrose concentrations may develop less severe enamel demineralization. Supported by NIH/NIDCR R21 DE018390-01A2.