The aim of this study is to determine the effectiveness of Er:YAG pulse therapy for achieving pulpal analgesia in pediatric patients and to quantify the duration and extent of any effects assessed.

Design: a randomized split-mouth study with two-way repeated measures design.

The intention of the technique of "pre-emptive laser analgesia" is to reduce sensation in that small percentage of patients who may experience unpleasant sensations during caries removal. Laser analgesia is a non-invasive, non-thermogenic bio-modulation of the dental pulp reactivity aiming for reduction of impulse formation of the pulpal nociceptors. It is based on the idea that parallel with the ablative high-energy level laser action, simultaneous low level laser therapy (LLLT) may occur. We hypothesize that when operating at pulse energies below the Er:YAG laser ablation threshold of tooth structure, the laser energy leads to loss of impulse conduction of type A-delta nerve fibers in the dental pulp, leading to an analgesic effect.

Exclusion criteria:

• Children who are considered medically compromised or medically complex patients. The absence of disease is confirmed by anamnestic interview with a parent or a care-giver of the child and excludes general acute or chronic disease, cognitive impairment, psychogenic nonepileptic events, radiotherapy in the maxillofacial region due to malignant process.
• Patients who are undergoing therapy with neurological, sedative, analgesic and/or anti-inflammatory drugs 7 days prior to treatment.
• Children, who are first time ever dental patients.

Inclusion criteria:

• Patients, identified as positive or definitely positive through Frankl behavioral rating scale.
• Patients who are not undergoing treatment or have been treated 6 months prior to inclusion with remineralizing agents.
• Patients, requiring conservative treatment of occlusal, caries on foramen caecum, and/or proximal caries on two first permanent upper jaw molars without prior restorations or dental sealants. Lesions are to be classified as moderate caries by the International caries detection and assessment system (ICDAS) with code 03 or code 04, which do not present spontaneous unprovoked pain, percussion or palpation pain or other symptoms, indicating of pulpal pathology. Included are carious lesions only on vital teeth, involving up to half of the dentine thickness, with no periodontal pathology. Laser fluorescence diagnosis of adjacent lesions with DIAGNODENT is limited to 20 - 35 scores included.
• Included are first molars which are not affected by hypoplasia or hypomineralization.

Obtained informed consent from parents or gave-givers to participate in the study, in which laser treatment and study procedures are explained in appropriate manner.