PJD
tooth
BLIND
The PJD-UNIT and HAP powder was provided by SANGI CO., LTD. in accordance with a joint research contract with Tohoku University. Test treatment was performed by operators. We selected three blinded evaluators who were not involved in the test treatment. Following the baseline examination and randomized allocation, the test teeth were cleaned using a rotary toothbrush with rubber cup by operator. Then, to blind the patient, the test tooth was subjected to both dummy and test treatments.For PJD treatment, a dummy treatment was provided first. The dummy treatment was performed by application of water, instead of TMD, using an applicator brush for 40 s. The tooth was then isolated using a rubber dam for PJD treatment. The tooth was sprayed with HAP powder using the PJD-UNIT for 1 min under the following conditions: supply pressure, 0.5 MPa; powder fill volume, 5 g; and nozzle scan speed, approximately 5 mm/s; HAP particle. The distance between the tip of the spray nozzle and tooth surface was kept at about 3 mm within an allowable range of 1–5 mm. The excess powder was vacuumed using extra and intra oral suctions. Finally, the HAP layer formed on the tooth surface was polished using a diamond paste (Diamond Polisher Paste, GC, Japan).