Table 4 Summery of all the included studies

1

El-Bialy et al.

LIPUS combined with distraction enhanced mandibular incisor growth and eruption.

2

Bona et al.

150 mW/cm(2).

Single ultrasound exposure increased the expression of transcripts for COL-I and ALP after 24 h; the expression of OPG and RANKL also increased after 1 and 4 h, respectively. Cultured cementoblasts receiving ultrasound stimulation for 6 days showed a significant (p < 0.05 or 0.01) increase in cell number and collagen synthesis. ALP activity and OPG synthesis were also significantly (p < 0.05) upregulated by ultrasound stimulation with 150 mW/cm(2).

These results demonstrated that ultrasound stimulation especially with 150 mW/cm(2) might be a better candidate as a medical remedy to protect against root resorption and/or accelerate its repair.

3

Inubushi et al.

30 mW/cm2

LIPUS exposure significantly reduces root resorption by the suppression of cementoclastogenesis by altering OPG/RANKL ratio during orthodontic tooth movement without interfering tooth movement. LIPUS may be an effective tool to prevent root resorption during tooth movement and is applicable to clinical use in near future.

4

Scheven et al.

30 mW/cm2

The effect of ultrasound on odontoblast-like cells and observed that the expression of Collagen-I, Osteopontin (OPN), TFGβ1 and heat shock protein (hsp) increased after ultrasound application. An interesting finding of this study was the effect of ultrasound on hsp 25/27, suggesting the role of this protein in response of odontoblasts to ultrasound

5

Rego et al.

30 mW/cm2

Increased PGE2 formation in LIPUS (30 mW/cm2) treated cells compared to control. Also, the gene expression levels of ALP, bone morphogenic protein 2 (BMP-2) and osteopontin (OPN) significantly increased in LIPUS treated group compared to control. In addition, LIPUS stimulation upregulated the mRNA expression levels of EP2 and EP4, however, the mRNA expression levels of EP1 and EP3 which were unaffected, thus, suggesting that LIPUS therapy can promote cementoblast differentiation through EP2/EP4 receptor pathway(

6

El-Bialy et al.- clinical trial

30 mW/cm2

The stimulatory effect of LIPUS on cementum regeneration and repair. Using a split mouth design, they tipped the premolars facially with an initial force level of 50 gm accompanied with LIPUS therapy (30 mW/cm2) on left side whereas the right side was used as a control. LIPUS was applied for 20 min/day for four weeks after which the teeth were extracted and were analyzed. A significant decrease in the number and surface area of resorption lacunae was observed in the LIPUS treated premolars compared to control. Also LIPUS treated premolars showed significant deposition of new cellular cementum (reparative cementum) compared to control

7

Al-Daghreer et al.

30 mW/cm2

Observed less root resorption in the LIPUS (30 mW/cm2) treated teeth compared to control. They reported that number of resorption lacunae, total volume of resorption lacunae and percentage of tooth root resorption was significantly less in the LIPUS group compared to control. Also, they observed deposits of new cellular cementum on LIPUS treated roots compared to control. Moreover, they also noted that LIPUS treated group exhibited significantly thicker cementum on middle and apical third of the root compared to control. The distribution of osteoclast and odontoclast along the root surfaces were also reported.

8

Liu et al.

Rat model also reported decreased number of RL in the LIPUS treated teeth compared to contro

9

Wierzbicki et al.

The mean percentage of root resorption of the teeth after undergoing one year of regular orthodontic treatment to be 0.88% compared to 0.55% of the control group in this study, where the teeth were subjected to a fairly low level of torque for only 4 weeks. This further signifies the deleterious effect of torque on root resorption.

10

Vafaeian et al.

The quantitative relationship between the thicknesses of regenerated cementum and ultrasound power. He reported a non-uniform distribution of ultrasound pressure amplitudes on different root surfaces.

11

Chan et al. clinical study

Root resorption with heavy tensile forces

12

Xue et al.

Rat model demonstrated that LIPUS can accelerate orthodontic tooth movement via activation of Bone Morphogenic Protein-2 (BMP-2) signalling pathway

13

Barley et al.

Applied 2.85 N-mm (285 g-mm) of torque and observed more resorption at the apical level than at middle and cervical level.

14

Casa et al.

Applied 6 N-mm of torque and reported severe root resorption at the apex.