Objective To analyze the clinical efficacy of Vector ultrasonic system versus traditional ultrasonic device in the treatment of chronic periodontitis.Methods A total of 86 patients with chronic periodontitis treated at a Nanyang hospital from March 2014 to April 2015 were included in our study.These patients were randomly allocated into the trial group（Vector ultrasonic system）or the control group（traditional ultrasonic device）by using a random number table（n=43 for each group）.The Visual Analogue Scale（VAS）was used to assess the pain intensity before

during and one week after subgingival scaling treatment.Other clinical parameters including periodontal depth（PD）

bleeding on probing（BOP）and plaque index（PLI）were assessed before and 3 weeks after treatment.The degree of bioaerosol contamination in the dental clinic was compared between the two groups after treatment.Results Before treatment

the VAS score was comparable between the two groups（P>0.05）;during and one week after treatment

the VAS score was increased in both groups compared with that before treatment

with significantly greater reduction in the trial group（P<0.05）.At one week after treatment

21 patients in the control group reported increased tooth sensitivity

but such a complaint was not observed in the trial group.Before treatment

the PD

BOP and PLI were generally similar between the two groups（P>0.05）;at 3 weeks after treatment

the PD

BOP and PLI were reduced in both groups compared with those before treatment

with significantly greater reductions in the trial group（all P<0.05）.The bacterial colony count in the dental clinic in the trial group was 53.98±25.28 cfu/m3

which was significantly lower than that in the control group（135.18±30.88 cfu/m3）（P<0.05）.Conclusion Vector ultrasonic system is highly effective in treating chronic periodontitis

which is associated with less pain and better patient compliance with return visits.Besides

it can also decrease bioaerosol contamination in the dental clinic and reduce the risk of doctor-patient cross-infection

and thus it is worthy of widespread clinical application.