Clinical, Radiographic and Patient's Acceptance

In all teeth, local anaesthesia was administered using 7.0 mg/kg 4% articane + 1: 100,000 epinephrine (with a maximum total dosage of 500 mg)

- Rubber dam isolation was done.

Access cavity preparation:

• In all groups, caries removal was done with a sterile #330 high-speed bur, and coronal access cavity preparation was done with a sterile #4 high-speed round bur using high speed hand piece and water coolant. The access cavity was then refined using a sterile high-speed fissure bur. LASER operating parameters: Figure (10)

• Wavelength: 2780 nm

• Repetition rate: 15 Hz

• Water spray: 80

• Air : 60

• Emission mode: Free-running pulsed

• Tip: MZ 10- 6 mm, Zip Tip

• Average power: 8 Watt The coronal pulp was amputated by a sterile sharp excavator, the amputated sites were rinsed with water. Hemorrhage was controlled by placing sterile, saline- wetted cotton pellets on the radicular pulp stumps under slight pressure (Thompson et al., 2001) for 5 min for primary hemostasis ( J Dent Res 84(12) 2005). At this stage, the achievement of complete hemostasis was an inclusion criterion. If bleeding recommenced afterwards, partial pulpectomy was performed and the tooth was excluded from the study.

• After achieving complete haemostasis pulp stumps were treated according to each group: Group1: (control group)

• A cotton pellet that was moistened with 1:5 diluted bottle of FC (Formacresol, PREVEST DenPro, Digiana, Jammu, India) was placed over the pulp stumps for 5 minutes. After removal of the cotton, the fixed pulp stumps were capped with reinforced zinc oxide and eugenol base (Zinconol, PREVEST DenPro, Digiana, Jammu, India). Group2: (Diode LASER group)

• All patients, parents and clinical staff were requested to wear appropriate eye protection goggles during laser application, Figure (12). After achieving hemostasis, pulp stumps was treated with Diode LASER (980 nm).If hemostasis was not achieved, the process was repeated one more time until adequate hemostasis was achieved, Figure (15, 16). Diode LASER radiation (wavelength 980 nm) was delivered to the canal orifices with a special handpiece and fiber glass of 200 μm diameter, Figure (13), the parameters were set at: Figure (14) Emission mode: Pulsed contact mode Time: 2 seconds. Power: 2 Watt power with average power of 1 Watt and total energy of one spot, corresponding to two minutes and 31 seconds exposure was 4.0 J/cm 2. Group3: (Erbium:Chromium,YSGG LASER group) Pulp tissues in this group were treated with Erbium:Chromium,YSGG LASER (2780 nμ). (Waterlase Biolase®, Biolase, Inc., San Clemente, California, USA) Once the pulp chamber was opened, the laser tip was placed into the pulp chamber using for approximately 15 seconds. In most instances, this was repeated three times. If hemostasis was not achieved, the process was repeated one more time until adequate hemostasis was achieved. Er: Cr, YSGG LASER radiation (wavelength 2780 nμ) was delivered with a special handpiece, and a tip: MZ 10- 6 mm, Zip Tip, to the canal orifices.