Table 1 Descriptive data and statistics of all outcome parameters evaluated

From: Regular nicotine intake increased tooth movement velocity, osteoclastogenesis and orthodontically induced dental root resorptions in a rat model

  

Descriptive statistics

Global test

Post hoc test Δ force (F)/F+nicotine

Parameters Evaluated

Experimental conditions (n=7 per group)

 

M

SD

min.

max.

F/H/U

df1-2 (z)

P-value

r

P-value

95% CI of ΔM

Serology (after 14 days of OTM, nicotine bioavailability (cotinine) and systemic inflammation (IL-6))

 IL-6—blood serum concentration in ng·mL−1 (n=4/grp.)

Control (PBS)

0.9

0.7

0.1

1.7

17.407F

2

***0.001

0.89

**0.009 T

1.6–9.9

 

Orthodontic force

3.7

0.8

2.5

4.3

      
 

Force+nicotine

9.5

3.5

6.3

14.3

      

 Cotinine—blood serum concentration in μg·L−1 (n=5/grp.)

Control (PBS)

5.0

0.0

5.0

5.0

25.000U

2.785z

**0.008

0.88

**0.008 U

283.7–623.9

 

Force+nicotine

458.8

137.0

258.0

569.0

      

CBCT (radiology, experiment A, OTM within 14/28 days, velocity of orthodontic tooth movement)

 First upper left molar M1—orthodontic tooth movement within 14/28 days (tipping, in °)

Control (PBS)

14 days

−0.3

0.9

−1.6

0.8

91.183F (group)

59.639F (time)

2 (group)

1 (time)

***<0.001 (group)

***<0.001 (time)

0.91 (group)

0.88 (time)

***<0.001 T

1.4–4.5

  

28 days

0.0

1.5

−1.8

2.0

      
 

Orthod. force

14 days

3.6

1.6

1.7

5.3

      
  

28 days

6.3

1.5

4.1

7.8

      
 

Force+nicotine

14 days

6.1

1.2

4.5

7.9

      
  

28 days

9.7

1.1

8.5

11.4

      

 Second upper left molar M2—orthodontic tooth movement within 14/28 days (in mm)

Control (PBS)

14 days

0.0

0.0

0.0

0.1

125.398F (group)

219.362F (time)

2 (group)

1 (time)

***<0.001 (group)

***<0.001 (time)

0.94 (group)

0.96 (time)

**0.004 GH

0.1–0.4

  

28 days

0.0

0.1

−0.1

0.1

      
 

Orthod. force

14 days

0.4

0.1

0.3

0.5

      
  

28 days

0.7

0.1

0.6

0.8

      
 

Force+nicotine

14 days

0.6

0.1

0.5

0.7

      
  

28 days

1.0

0.2

0.8

1.3

      

 Third upper left molar M3—mesial drift within 14/28 days (in mm)

Control (PBS)

14 days

0.0

0.0

0.0

0.1

40.659F (group)

40.210F (time)

2 (group)

1 (time)

***<0.001 (group)

***<0.001 (time)

0.83 (group)

0.83 (time)

**0.002 T

0.1–0.3

  

28 days

0.0

0.1

−0.2

0.2

      
 

Orthod. force

14 days

0.1

0.1

0.0

0.2

      
  

28 days

0.3

0.1

0.2

0.5

      
 

Force+nicotine

14 days

0.2

0.1

0.2

0.3

      
  

28 days

0.5

0.1

0.4

0.6

      

RT–qPCR (after 14 days of OTM, experiment B, inflammation and osteoclast activity within the dental-periodontal tissue)

 IL-1β—normalized relative gene expression (geNorm)

Control (PBS)

0.04

0.03

0.02

0.10

42.52F,W

2–7.301

***<0.001

0.92

**0.002 GH

0.6–1.9

 

Orthodontic force

0.42

0.22

0.16

0.75

      
 

Force+nicotine

1.65

0.57

0.71

2.26

      

 IL-6—normalized relative gene expression (geNorm)

Control (PBS)

0.01

0.01

0.00

0.02

32.93F,W

2–7.301

***<0.001

0.90

***<0.001 GH

0.6–1.5

 

Orthodontic force

0.47

0.17

0.29

0.74

      
 

Force+nicotine

1.53

0.39

1.03

2.05

      

 IL-8-equivalent (CXCL1)—normalized rel. gene expression (geNorm)

Control (PBS)

0.09

0.05

0.03

0.17

78.85F,W

2–7.379

***<0.001

0.87

**0.002 GH

0.4–1.6

 

Orthodontic force

0.89

0.27

0.62

1.23

      
 

Force+nicotine

1.90

0.49

1.18

2.64

      

 CTSK—normalized relative gene expression (geNorm)

Control (PBS)

0.04

0.01

0.04

0.05

33.103F,W

2–7.421

***<0.001

0.90

***0.001 GH

2.1–5.6

 

Orthodontic force

0.31

0.10

0.19

0.49

      
 

Force+nicotine

4.15

1.53

2.35

6.44

      

 CLCN7—normalized relative gene expression (geNorm)

Control (PBS)

0.03

0.01

0.02

0.04

67.400F,W

2–7.603

***<0.001

0.93

**0.007 GH

0.5–2.4

 

Orthodontic force

0.34

0.06

0.27

0.41

      
 

Force+nicotine

1.79

0.79

0.92

3.00

      

 Histomorphometry and Histochemistry (M2 distobuccal root, after 14 days of OTM, experiment C, OIIRR and osteoclast activity)

 TRAP+ area in % in PDL per mm2 root area (TRAP density)

Control (PBS)

3.8

2.1

1.0

6.9

33.692F,W

2–11.0

***<0.001

0.90

**0.002 GH

4.7–17.7

 

Orthodontic force

10.1

2.9

5.1

13.9

      
 

Force+nicotine

21.3

5.4

14.6

30.1

      

 Relative dentine root resorption in %

Control (PBS)

0.0

0.0

0.0

0.0

18.491H

2

***<0.001

0.95

***0.001 U

4.4–9.9

 

Orthodontic force

2.6

0.5

2.0

3.4

      
 

Force+nicotine

9.7

2.3

6.9

13.5

      
  1. CBCT, cone-beam computed tomography; CI, confidence interval; df, degrees of freedom; F, test statistic of one-way/mixed (CBCT) ANOVA; GH, Games–Howell post hoc test; H, test statistic of two-sided Kruskal–Wallis H-test; IL, interleukin; M, arithmetic mean; max., maximum; min., minimum; n, number of animals; OTM, orthodontic tooth movement; OIIRR, orthodontically induced inflammatory root resorption; P, significance value; r, effect size (Pearson’s correlation coefficient); PDL, periodontal ligament; PBS, phosphate-buffered saline; RT–qPCR, reverse transcription quantitative real-time; PCR, polymerase chain reaction; SD, standard deviation; T, Tukey’s Highly Significant Difference post hoc test; TRAP, tartrate-resistant acid phosphatase; U, test statistic of two-sided Mann–Whitney U-test; W, Welch test corrected ANOVA; z, standardized test statistic; ΔM, difference of arithmetic means of group force (2) and group force+nicotine (3).
  2. Gene expression was normalized via the reference genes PPIB/YWHAZ (combination). Bold values are indicate P values, which are statistically significant (P≤0.05). */**/***P≤0.05/0.01/0.001.
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