Evaluation of Three Assessment Methods: Screening for Dental Erosive Capacity

There is a need for an effective method to measure the erosive potential of commercial mouth rinses in relation to dental enamel.  Measures such as pH or titratable acidity have been used as indicators of erosive potential, however, these quantities are not necessarily indicative of the erosive potential as other chemical interactions such as calcium binding, are not considered.  Other methods such as contact X-ray microradiography, Knoop indent, or profilometry have been shown to be able to directly and distinctly measure erosion and demineralization; however these methods are more difficult to perform and require significant equipment cost.  Objective: develop a facile screening method requiring less specialized equipment that accurately predicts enamel erosion that can be validated by other methods.  Methods: a Ca-PO₄ indicator solution of 0.760 mM calcium and 1.268 mM phosphate (near saturation with respect to hydroxyapatite) at pH 5.05±0.05 is used.  250 µL of a potentially erosive solution is added to 25.0 mL of the Ca-PO₄ indicator solution and the change in pH is recorded.  Results of this screening method were compared to erosion potential determined by x-ray microradiography and titratable acidity. Results: The ranking of the erosive potential of the solutions tested was the same with all three methods (n³3).

 

Solution/Test Method	Ca-PO4 indicator -d(pH)	Titratable Acidity (Eq/L)	X-ray method (µm)
0.3% Citrate pH 3.9	0.90±0.01	18.8±0.3	34±2
1.0% Citrate pH 3.9	1.09±0.01	62.9±0.4	38±3
1.0% Citrate pH 2.54	1.63±0.01	106.8±0.6	129±3
Oral Rinse pH 4.2 (A)	0.77±0.02	7.4±0.05	11±2
Oral Rinse pH 4.1 (B)	0.02±0.00	0.2±0.01	2±1
Oral Rinse pH 3.8 (C)	0.24±0.00	1.9±0.01	2±1
Oral Rinse pH 3.8 (D)	0.22±0.00	1.4±0.01	14±2

Conclusions: The Ca-PO₄ screening method is effective for the assessment of erosive potential of oral rinses.  The method has the advantage of being available to most laboratories.  Supported by: R01DE14707, ADAF, NIST.