{'fraction_non_alphanumeric': 0.017675050985723997, 'fraction_numerical': 0.010876954452753228, 'mean_word_length': 5.1078838174273855, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Dissolution studies of bovine dental enamel surfaces modified by high‐speed scanning ablation with a λ = 9.3‐µm TEA CO2 laser

Previous studies have demonstrated that lasers can be used to modify the chemical composition of dental enamel to render the mineral phase more resistant to acid dissolution with minimal peripheral thermal damage. Transverse excited atmospheric (TEA) CO2 lasers tuned to the strong mineral absorption of hydroxyapatite (HAP) near λ = 9 µm are well‐suited for the efficient ablation of dental hard tissues if the laser‐pulse is stretched to greater than 5–10 microseconds to avoid plasma shielding phenomena. Moreover, TEA CO2 lasers can be operated at very high repetition rates and are inherently less expensive and more versatile than Er:YAG and Er:YSGG solid‐state lasers. In this study a λ = 9.3‐µm TEA CO2 with a pulse duration of 8 microseconds and a repetition rate of 300 Hz was used to uniformly treat bovine enamel surfaces at ablative irradiation intensities. We hypothesized that a uniform surface layer of modified enamel of improved crystallinity and CaP phase composition would be formed with an enhanced resistance to acid‐dissolution in the ablated areas at higher scanning rates used with the water spray. Such a modified layer of enamel formed at the base and walls of a cavity preparation under the irradiation conditions employed in this study have the potential to inhibit secondary caries under sealants and restorations.