Introduction
Materials and methods
Study design
Selection of participants
Sample size estimation
Orthodontic treatment
Low-level laser irradiation
Outcome assessment
Subjective pain assessment
Measurement of maximum voluntary bite force
Periodontal clinical examination and supragingival bacteria analysis
Analysis of cytokines in gingival crevicular fluid
Statistical analysis
Results
Characteristics of the study participants
Results of subjective pain perception
Time-points | Laser group | Placebo group | Intergroup comparison (P) | |||||
---|---|---|---|---|---|---|---|---|
Average (SD) | Median (IQR) | Min-max | Average (SD) | Median (IQR) | Min-max | |||
1-hour (T1) | 4.2 (7.8) | 0.0 (5.0) | 0.0–32.0 | 5.9 (9.3) | 0.0 (8.0) | 0.0–30.0 | 0.14 | |
6-hour (T2) | 6.3 (11.3) | 0.0 (8.0) | 0.0–48.0 | 8.9 (12.0) | 5.0 (10.5) | 0.0–42.5 | 0.03* | |
24-hour (T3) | 8.1 (13.1) | 2.0 (10.0) | 0.0–40.0 | 15.0 (21.9) | 4.0 (26.5) | 0.0–81.0 | 0.02* | |
2-day (T4) | 4.2 (8.9) | 0.0 (3.5) | 0.0–35.0 | 6.9 (12.6) | 1.0 (7.5) | 0.0–45.5 | 0.25 | |
3-day (T5) | 2.1 (4.7) | 0.0 (1.0) | 0.0–21.0 | 4.1 (7.9) | 0.0 (3.0) | 0.0–30.0 | 0.07 | |
4-day (T6) | 1.9 (4.6) | 0.0 (0.5) | 0.0–20.0 | 2.9 (6.4) | 0.0 (1.3) | 0.0–26.0 | 0.53 | |
5-day (T7) | 1.9 (4.7) | 0.0 (0.5) | 0.0–21.0 | 2.1 (5.4) | 0.0 (0.5) | 0.0–22.0 | 0.92 | |
6-day (T8) | 1.2 (4.3) | 0.0 (0.0) | 0.0–22.0 | 2.7 (5.0) | 0.0 (2.8) | 0.0–15.0 | 0.09 | |
7-day (T9) | 2.1 (5.1) | 0.0 (0.5) | 0.0–22.5 | 2.6 (5.6) | 0.0 (1.5) | 0.0–19.0 | 0.40 | |
Maximum pain over 7 days | 10.6 (13.7) | 8.0 (9.5) | 0.0–48.0 | 18.0 (21.6) | 10.0 (31.0) | 0.0–81.0 | 0.02* | |
Intragroup comparison (P) | 0.00** T2 > T8*; T3 > T5**; T3 > T6**; T3 > T7**; T3 > T8**; T3 > T9** | 0.00** T3 > T1**; T3 > T4*; T3 > T5**; T3 > T6**; T3 > T7**; T3 > T8**; T3 > T9** |
Time-point | Laser group | Placebo group | Intergroup comparison (P) | ||||
---|---|---|---|---|---|---|---|
Average (SD) | Median (IQR) | Min-max | Average (SD) | Median (IQR) | Min-max | ||
1-day (T1) | 10.3 (10.9) | 7.5 (15.2) | 0–36.7 | 12.9 (13.0) | 9.0 (16.8) | 0–46.0 | 0.04* |
1-week (T2) | 8.4 (11.7) | 4.8 (8.8) | 0–45.0 | 12.7 (17.0) | 6.5 (13.1) | 0–61.0 | 0.03* |
1-month (T3) | 8.1 (11.7) | 5.0 (8.1) | 0–47.5 | 11.9 (17.1) | 5.0 (15.3) | 0–70.0 | 0.07 |
9-week (T4) | 4.4 (6.4) | 1.8 (5.5) | 0–23.2 | 6.5 (7.1) | 3.5 (11.7) | 0–24.0 | 0.02* |
3-month (T5) | 5.8 (9.1) | 2.7 (7.9) | 0–43.2 | 7.3 (11.4) | 1.5 (9.4) | 0–41.0 | 0.84 |
Intragroup comparison (P) | 0.00** T1 > T4*; T1 > T5* | 0.00** T1 > T5* |
Laser group | Placebo group | P for intergroup comparison | |||||
---|---|---|---|---|---|---|---|
Time-point | Mean (SD) | 95% CI | Decrease compared to T0 (%) | Mean (SD) | 95% CI | Decrease compared to T0 (%) | |
Baseline (T0) | 23.50 (14.47) | 17.53–29.47 | 0 | 24.82 (14.27) | 18.93–30.71 | 0 | 0.26 |
1-day (T1) | 15.37 (12.03) | 10.40–20.33 | 34.61 | 13.33 (11.41) | 8.62–18.04 | 46.31 | 0.09 |
1-week (T2) | 11.15 (8.95) | 7.45–14.84 | 52.57 | 8.13 (7.08) | 5.20–11.05 | 67.26 | 0.02* |
1-month (T3) | 13.57 (11.02) | 9.02–18.12 | 42.27 | 10.63 (8.19) | 7.24–14.01 | 57.19 | 0.04* |
9-week (T4) | 13.30 (11.71) | 8.47–18.13 | 43.40 | 10.93 (10.84) | 6.45–15.40 | 55.98 | 0.08 |
3-month (T5) | 17.09 (15.93) | 10.51–23.66 | 27.29 | 14.80 (13.93) | 9.05–20.55 | 40.37 | 0.09 |
P for intragroup comparisons | 0.00** T0 > T1*; T0 > T2**; T0 > T3**; T0 > T4* | 0.00** T0 > T1**; T0 > T2**; T0 > T3**; T0 > T4** |
Results of periodontal indices and supragingival bacteria load
Measurements | Laser | Placebo | P value for intergroup comparison | |||
---|---|---|---|---|---|---|
Mean (SD) | Mean change from baseline (SD) | Mean (SD) | Mean change from baseline (SD) | For mean value | For change amount | |
PPD (mm) | ||||||
Baseline (T0) | 1.62 (0.36) | — | 1.62 (0.32) | — | 0.90 | — |
1-month (T1) | 1.70 (0.43) | 0.08 (0.63) | 1.75 (0.34) | 0.13 (0.47) | 0.24 | 0.37 |
3-month (T2) | 1.59 (0.35) | − 0.03 (0.39) | 1.65 (0.37) | 0.03 (0.36) | 0.13 | 0.27 |
6-month (T3) | 1.76 (0.33) | 0.13 (0.46) | 1.77 (0.30) | 0.15 (0.35) | 0.79 | 0.88 |
P value for intragroup comparison | 0.33 | 0.17 | 0.19 | 0.22 | — | — |
PI | ||||||
Baseline (T0) | 0.32 (0.25) | — | 0.36 (0.24) | — | 0.15 | — |
1-month (T1) | 0.41 (0.25) | 0.09 (0.25) | 0.59 (0.30) | 0.22 (0.22) | 0.00** | 0.01** |
3-month (T2) | 0.44 (0.19) | 0.12 (0.22) | 0.50 (0.22) | 0.14 (0.19) | 0.03* | 0.59 |
6-month (T3) | 0.53 (0.31) | 0.25 (0.34) | 0.59 (0.37) | 0.26 (0.38) | 0.10 | 0.71 |
P value for intragroup comparison | 0.01** T0 < T2**; T0 < T3* | 0.25 | 0.00** T0 < T1**; T0 < T2*; T0 < T3* | 0.07 | — | — |
GI | ||||||
Baseline (T0) | 0.51 (0.30) | — | 0.51 (0.24) | — | 0.99 | — |
1-month (T1) | 0.55 (0.30) | 0.04 (0.37) | 0.62 (0.33) | 0.11 (0.34) | 0.10 | 0.06 |
3-month (T2) | 0.51 (0.29) | 0.00 (0.36) | 0.68 (0.25) | 0.17 (0.27) | 0.00** | 0.01* |
6-month (T3) | 0.61 (0.32) | 0.11 (0.38) | 0.71 (0.28) | 0.22 (0.30) | 0.04* | 0.19 |
P value for intragroup comparison | 0.07 | 0.03* T2-T0 < T3-T0* | 0.01* T0 < T2*; T0 < T3** | 0.09 | — | — |
BOP(%) | ||||||
Baseline (T0) | 12.24 (8.08) | — | 14.25 (7.48) | — | 0.29 | — |
1-month (T1) | 12.29 (9.35) | 0.05 (11.76) | 17.44 (9.58) | 3.19 (11.12) | 0.02* | 0.27 |
3-month (T2) | 12.00 (10.06) | − 0.24 (12.19) | 12.81 (7.91) | − 1.44 (10.19) | 0.73 | 0.70 |
6-month (T3) | 12.04 (10.88) | − 0.29 (12.68) | 17.62 (9.83) | 3.15 (11.76) | 0.06 | 0.22 |
P value for intragroup comparison | 1.00 | 0.97 | 0.26 | 0.12 | — | — |
CAL (mm) | ||||||
Baseline (T0) | 3.09 (1.37) | — | 3.17 (1.48) | — | 0.61 | — |
1-month (T1) | 3.21 (1.05) | 0.12 (0.88) | 3.32 (1.28) | 0.15 (0.88) | 0.52 | 0.75 |
3-month (T2) | 3.03 (1.13) | − 0.05 (0.52) | 3.16 (1.24) | − 0.01 (0.52) | 0.44 | 0.57 |
6-month (T3) | 3.25 (1.16) | 0.14 (0.67) | 3.29 (1.18) | 0.12 (0.67) | 0.82 | 0.83 |
P value for intragroup comparison | 0.24 | 0.15 | 0.64 | 0.53 | — | — |
GR (mm) | ||||||
Baseline (T0) | 1.62 (1.23) | — | 1.78 (1.45) | — | 0.34 | — |
1-month (T1) | 1.49 (1.08) | −0.13 (0.50) | 1.62 (1.28) | −0.16 (0.56) | 0.42 | 0.69 |
3-month (T2) | 1.45 (1.07) | −0.16 (0.50) | 1.51 (1.18) | −0.28 (0.68) | 0.71 | 0.30 |
6-month (T3) | 1.46 (1.17) | −0.18 (0.59) | 1.55 (1.15) | −0.27 (0.74) | 0.59 | 0.44 |
P value for intragroup comparison | 0.35 | 0.37 | 0.35 | 0.41 | — | — |
Results of GCF levels of biomarkers
Time-point | Laser group | Placebo group | Intergroup comparison of change (P) | ||||
---|---|---|---|---|---|---|---|
Median (IQR) | Min-max | Change from baseline in median (IQR) | Median (IQR) | Min-max | Change from baseline in median (IQR) | ||
IL-1ß | |||||||
Baseline | 0.39 (0.49) | 0.10–2.36 | — | 0.26 (0.25) | 0.00–2.68 | — | — |
1-day | 0.35 (0.39) | 0.08–2.37 | 0.01 (0.30) | 0.51 (0.46) | 0.17–2.95 | 0.16 (0.47) | 0.01** |
1-week | 0.47 (0.52) | 0.11–2.29 | 0.07 (0.49) | 0.44 (0.26) | 0.16–2.28 | 0.03 (0.36) | 0.47 |
1-month | 0.49 (0.44) | 0.09–1.55 | − 0.04 (0.51) | 0.41 (0.40) | 0.04–4.38 | 0.10 (0.44) | 0.03* |
9-week | 0.45 (0.34) | 0.09–3.05 | − 0.01 (0.42) | 0.44 (0.28) | 0.13–3.80 | 0.08 (0.36) | 0.36 |
Intragroup comparison (P) | 0.31 | 0.25 | |||||
PGE2 | |||||||
Baseline (T0) | 0.52 (2.19) | 0.00–6.70 | — | 0.35 (1.57) | 0.00–4.82 | — | — |
1-day (T1) | 0.88 (2.30) | 0.00–7.87 | −0.01 (0.43) | 1.25 (2.76) | 0.00–8.30 | 0.37 (1.24) | 0.02* |
1-week (T2) | 0.55 (1.98) | 0.00–4.18 | −0.02 (1.02) | 0.91 (1.70) | 0.00–6.29 | 0.18 (1.04) | 0.00** |
1-month (T3) | 0.84 (3.09) | 0.00–5.85 | − 0.02 (2.22) | 0.74 (1.75) | 0.00–7.55 | 0.10 (0.89) | 0.32 |
9-week (T4) | 0.73 (1.89) | 0.00–4.19 | 0.00 (1.21) | 0.69 (1.27) | 0.00–3.63 | 0.00 (0.70) | 0.65 |
Intragroup comparison (P) | 0.81 | 0.01* T1 > T0; T1 > T4 | |||||
SP | |||||||
Baseline (T0) | 0.34 (0.90) | 0.00–3.56 | — | 0.26 (0.73) | 0.00–2.14 | — | — |
1-day (T1) | 0.55 (0.83) | 0.00–3.11 | 0.08 (0.46) | 0.97 (0.93) | 0.00–5.74 | 0.26 (0.97) | 0.00** |
1-week (T2) | 0.33 (0.75) | 0.00–4.76 | 0.01 (0.66) | 0.18 (1.08) | 0.00–7.71 | 0.00 (0.39) | 0.81 |
1-month (T3) | 0.30 (0.65) | 0.00–5.15 | − 0.11 (0.77) | 0.26 (1.11) | 0.00–7.27 | 0.00 (0.63) | 0.12 |
9-week (T4) | 0.62 (0.77) | 0.00–8.01 | 0.10 (0.94) | 0.82 (1.24) | 0.00–4.08 | 0.47 (1.15) | 0.46 |
Intragroup comparison (P) | 0.39 | 0.00** T1 > T0, T1 > T2 |