Matjaz Lukac, Tomaz Suhovrsnik, Cene Filipic
J Laser Dent 2014;22(1):28-35
The aim of this in vitro study was to investigate the ablation eﬃcacy of an Er:YAG laser system equipped with a new Quantum Square Pulse (QSP) pulse duration modality, and to compare it with the ablation eﬃcacy of other erbium laser pulse duration modes. A reported advantage of the QSP mode is that it signiﬁcantly reduces the undesirable eﬀects of laser beam scattering and absorption in the debris cloud consisting predominantly of dehydrated hydroxyapatite which is ejected from the ablated tooth. The experiments were conducted on randomly chosen extracted human premolar and molar teeth which were stored in a physiological saline solution immediately following extraction. Before each ablation experiment, the tooth was positioned to have its surface perpendicular to the laser beam, and to be at focal distance of the noncontact laser handpiece. Measurements were made on enamel under water/air spray conditions. Each ablation data point represented an average obtained from diﬀerent cavities, each made with 10 or 20 consecutive pulses of the same laser ﬂuence delivered to the same spot. Ablation measurements were made with QSP, SSP, and SP pulse duration modes of the Er:YAG laser, and with the H mode of the Er,Cr:YSGG laser. The measured high ablation eﬃcacy of the QSP Er:YAG mode demonstrates that the reduction of undesirable eﬀects of laser-debris interaction results also in the enhancement of laser ablation eﬃcacy.