Abstract
Objective: The aim of the present study was to investigate the effect of sub-ablative Er:YAG and Er:YSGG laser radiation on the demineralization of human dental enamel in situ. Methods: Eighteen enamel specimens were prepared to this end, nine of which were irradiated at 8 J/cm2 with the Er:YSGG laser and nine at 6 J/cm2 with the Er:YAG laser (125 pulses per surface). Each test surface was assigned a control surface on the same specimen. Three healthy volunteers from each group subsequently wore three enamel specimens in situ for a period of 1 week. The demineralization was assessed by determining the surface microhardness according to Knoop (KH) before and after wearing. Results: Before wearing, the mean surface hardness measured on the control surfaces was 233 (SD 99) KH (CYSGG) and 162 (SD 59) KH (CYAG). After sub-ablative laser irradiation, the surface hardness values measured were already found to be lower compared to the untreated control surfaces (YSGG: 195 [SD 110] KH/YAG: 112 [SD 72] KH). Marked demineralization was observed on the control surfaces after 1 week of wearing in situ (CYSGG*: 60 [SD 57] KH; CYAG*: 53 [SD 9] KH). After wearing, the hardness on the irradiated test surfaces was ErYSGG*: 133 [SD 58] KH and ErYAG*: 89 [SD 28] KH, and was thus higher than on the control surfaces. Conclusions: The results indicate a tendency towards increased caries resistance following sub-ablative erbium laser irradiation. However, in an analysis of variance model with repeated measures, the tendency in this study failed to reach statistical significance(α = 0.05).
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