Protective effect of zinc-hydroxyapatite toothpastes on enamel erosion: Anin vitrostudy.
BACKGROUND
The aim of the present study was to test the impact of different toothpastes with Zinc-Hydroxyapatite (Zn-HAP) on preventing and repairing enamel erosion compared to toothpastes with and without fluoride.


METHODS
The following four toothpastes were tested: two toothpastes with Zn-HAP, one toothpaste with fluoride and one toothpaste without fluoride. An additional control group was used in which enamel specimens were not treated with toothpaste. Repeated erosive challenges were provided by immersing bovine enamel specimens (10 per group) in a soft drink for 2 min (6mL, room temperature) at 0, 8, 24 and 32 h. After each erosive challenge, the toothpastes were applied neat onto the surface of specimens for 3 min without brushing and removed with distilled water. Between treatments the specimens were kept in artificial saliva. Enamel hardness, after the erosive challenge and toothpaste treatment was monitored using surface micro-hardness measurements.


RESULTS
As expected, repeated erosive challenge by a soft drink for total of 8 min significantly reduced enamel surface hardness (ANOVA,p< 0.05). No re-hardening of the surface softened enamel was observed in the group treated with fluoride-free toothpaste. Surface hardness of the softened enamel increased when the specimens were treated with the fluoride toothpaste and the two toothpastes with Zn-HAP (p< 0.05).


CONCLUSIONS
Toothpaste with Zn-HAP resulted in significant enamel remineralisation of erosively challenged enamel, indicating that these toothpastes could provide enamel health benefits relevant to enamel erosion.Key words:Enamel, erosion, remineralization, surface hardness, toothpastes.
Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
Claudio
C
Poggio
Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
Chiara
C
Gulino
Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
Maria
M
Mirando
Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
Marco
M
Colombo
Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, Section of Dentistry, University of Pavia, Pavia, Italy.
Giampiero
G
Pietrocola