The study retrospectively registered in chictr.org.cn with registration ChiCTR2100051708 (01/10/2021). It was approved by the Ethical Committee of the Xi’an Central Hospital (2021-019). The study was conducted as a randomized controlled trial design. Participating subjects read and signed the informed consent prior to enrolling in the study. All methods were performed in accordance with the relevant guidelines and regulations.
Sample selection
This study was conducted on the patients of clinically diagnosed periodontal disease in the Department of Stomatology of Xi’an Central Hospital between May 2018 and September 2020. The sample size of our study was calculated after conducting a statistical analysis. All patients were selected according to strict inclusion and exclusion criteria and signed a written informed consent document before treatment.
The inclusion criteria were as follows: (1) at least 16 natural teeth present in the oral distributed in 4 quadrants; (2) Moderate to severe periodontal disease with presence of 3 or more quadrants in the oral cavity, each containing at least three teeth (excluding third molar, supernumerary tooth or minor tooth) with periodontal pocket depth (PD) of ≥ 4 mm; (3) male or female individuals 20 to 60 years of age could exactly follow the investigator’s arrangement and sign the informed consent form voluntarily; (4) Light to moderate smokers (< 10 cigarettes/day) corresponding to a significant percentage of patients in our daily practice.
Exclusion criteria were as follows: (1) System diseases that affect the periodontal disease, such as diabetes, acquired immunodeficiency syndrome; (2) Patients presenting with known adverse reactions to any component of the test agent; (3) Taking systemic nonsteroidal anti-inflammatory drugs or immunomodulatory agents within the past 6 months; (4) Pregnancy or lactation or non-cooperator.
Each patient’s quadrant was randomly divided into three treatment groups as follows: Control group received only mechanical therapy (SRP); Experimental group 1 received SRP + minocycline hydrochloride; Experimental group 2 received SRP + diode laser + minocycline hydrochloride. The remaining quadrant was treated with SRP. The test sites in a patient were treated with different treatment procedures to compare their effects within the same individual.
Treatment protocol
Every patient received oral hygiene instructions that included modified BASS brushing technique and mouth rinse without alcohol and chlorhexidine gluconate, twice a day after teeth brushing. Baseline examination including PD, CAL and bleeding index (BI) were performed 1 week before the experiment treatment. A week later, in the control group (Con), SRP was performed using manual Gracey curettes (Hu-Friedy, Chicago, USA) and ultrasonic scaler (EMS®, Switzerland). In the experimental group 1 (Exp 1), SRP was performed in the same manner as in Con group, followed by 10 mg minocycline hydrochloride (Sunstar, Japan) placed in periodontal pocket, once per week, for 4 weeks. In the experimental group 2 (Exp 2), the additional therapy was performed using Pilot laser (CAO Group, American) (tip diameter is 400 μm) 809 nm wavelength, 1.5 W power average output, operated in continuous mode. The laser probe paralleled to the root surface was gently inserted into the periodontal pocket, and moved evenly from bottom to coronally direction in order to covering the whole periodontal pocket. If the periodontal pocket depth < 6 mm, irradiation time was 30 s for one site; If the periodontal pocket depth > 6 mm, irradiation time was 45 s for one site. After irradiation, the periodontal pocket was alternately rinsed with 3% hydrogen peroxide and normal saline followed by minocycline hydrochloride as Exp 1.
Clinical recordings
The periodontal status of each patient was assessed at baseline and at 3 and 6 months after treatment. All the measurements were done by one dentist who underwent calibration training at the beginning of the study and three repeated measurements were performed and had to show a > 90% agreement for -1 mm between initial and repeated probes. Thereby allowing intra-experimental comparisons of the values.
The following clinical and biological observations were recorded:
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(1)
PD: by applying a calibrated periodontal probe (Hu-Friedy®, PQW7, USA) with a diameter of 0.5 mm, pocket depth was measured at 6 sites at each tooth (mesio-labial, mid-labial, distal-labial and mesio-palatal/lingual, mid-palatal/lingual and distal-palatal/lingual sites) as the distance from the gingival margin to the bottom of the pocket. The deepest PD from each tooth was selected as the test site.
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(2)
CAL: this was recorded at 6 sites in a manner similar to PD in relation to the cementoenamel junction. The deepest CAL from each tooth was selected as the test site.
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(3)
BI: using the same probing pressure, pocket bleeding was determined 30 s after probing and was assessed at 6 sites per tooth: 0- Healthy, no inflammation and bleeding; 1—Gingival inflammation changes, but no bleeding on probing; 2—Punctate bleeding; 3—Probing bleeding spreading along the gingival margin; 4—Bleeding over gingival sulcus; 5—Automatic bleeding.
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(4)
Secretion of inflammatory factor (TNF-α): After drying the surface of all target teeth, a perio paper (Harco, Tuston, CA, USA) was taken and zeroed in Periotron 8000 (OraflowCompany, USA), and then inserted into the gingival sulcus at 4 sites at each tooth (mesio-labial, distal-labial, mesio-palatal/lingual and distal-palatal/lingual) for 30 s. The filter paper was transfered to EP tube filled with 500 μL phosphate buffer (PBS) for 4 °C overnight, centrifuged at 1500 r/min for 4 min and then get the supernatant [18]. TNF-α was measured by enzyme-linked immunosorbent assay (ELISA).
Statistical analysis
Statistical analysis was performed using SPSS19.0 software (SPSS, Chicago, USA). All data were expressed as mean ± standard deviation (s.d.). All the data were normally distributed. The results of the parameters (PD, CAL, and TNF-α) were compared using the One-Way ANOVA among the groups at each time point. The Kruskal–Wallis test was applied to find the difference in the BI with each group at each time point. P-value < 0.05 was considered significant.