Comparison of Single and Multiple Low-Level Laser Applications After Rapid Palatal Expansion on Bone Regeneration in Rats

Effect of platelet rich plasma injection on bone formation in the expanded mid-palatal suture in rabbits: a randomized controlled animal study

BACKGROUND

Mid-Palatal suture expansion needs long retention period due to delayed bone formation in the expanded suture. Platelet-rich plasma (PRP) is a concentrated source of growth factors which increase bone formation. The aim of this study was to evaluate the effect of PRP injection on bone formation in expanded mid palatal suture in rabbits.

METHODS

In this prospective randomized controlled animal study, Twenty male rabbits (8-weeks-old) were subjected to mid-palatal expansion for 5 days. Animals were afterwards randomly divided into control group A & study group B. PRP was prepared and injected in the mid-palatal suture in animals belonging to group B only. After 6 weeks of retention, all animals were euthanized, and premaxillae were prepared for histological, histomorphometric and immunohistochemical analysis. Student t-test and paired t-test were used to compare the means of the two groups and within the same group respectively. Significance level set at p ≤ 0.05.

RESULTS

Histomorphometric analysis revealed a significant increase (p < 0.001) in the mean percentage of new bone in the study group (14.4%) compared to the control (1.4%). Suture width in study group was significantly wider than the control group (278.8 ± 9μms and 120.4 ± 3.4μms, p < 0.001). There was a significant increase in vascular density in study group than control group (309 ± 65.34 and 243.86 ± 48.1, p = 0.021). Osteopontin immuno-expression revealed a significant increase in optical density in study group than control group (0.21 ± 0.02 & 0.12 ± 0.01, p < 0.001).

CONCLUSIONS

In rabbit model, PRP injection can accelerate new bone formation in the expanded mid-palatal suture when compared to the control. This could hopefully result in a more stable midpalatal expansion and a reduced retention period.

Effect of Simvastatin and Low-Level Laser Therapy on Sutural Bone Formation After Expansion in Rats: Biomechanical, Computed Tomography and Immunohistochemical Assessment

Introduction: The application of low-level laser therapy (LLLT) and some medications have been shown to accelerate bone formation in rapid palatal expansion (RPE). A combination of these two therapeutic modalities may reduce the time required for the retention period. This study sought to assess the effects of simvastatin and LLLT, alone and combined, on sutural bone formation in rats. Methods: Sixty male Wistar rats averagely weighing 150 g were divided into five groups (n=12) of control (group 1), 5 mg simvastatin (group 2), 10 mg simvastatin (group 3), LLLT (group 4), and LLLT plus 10 mg simvastatin (group 5). The expansion appliance was placed in the parietal bone in all groups. One week after placing the appliance, the spring was fixed with Duralay acrylic resin to serve as a retainer during the rest of the experiment. The rats were sacrificed after 30 (for biomechanical and computed tomography [CT] assessments) or 60 days (for biomechanical, CT and immunohistochemical [IHC] assessments). Results: Groups 3 and 4 showed a significant improvement in osteogenesis (confirmed by CT findings, histological analysis and biomechanical test) compared to the control group. Group 5 was significantly superior to all other groups in terms of all parameters (P < 0.001). Group 2 and the control group were not significantly different (P>0.05). Conclusion: Although LLLT, simvastatin treatment and the combination of both significantly improved sutural bone formation in rats compared to the control group, the combined treatment showed significantly superior clinical results compared to other interventions.

Effect of Low-Level Laser Therapy on Bone Formation in Rapid Palatal Expansion: A Systematic Review

Introduction: Crossbite is a common malocclusion with a 7-23% prevalence rate. Treatment is based on the expansion of the mid-palatal suture (MPS) with Rapid Palatal Expansion(RPE) followed by a retention period to reach new bone maturation, enough to maintain the results stable. This systematic review was conducted to evaluate the effectiveness of low-level laser therapy (LLLT) in increasing bone formation in MPS. Methods: This article was written by the PRISMA checklist. Electronically, 3 databases, namely PubMed, Scopus, and Embase, were searched with the keywords selected based on PICO. Time (2010-2021) and language restrictions were performed. Results: 528 articles, out of which 374 studies were screened, were found, and 9 full-text articles were subsequently included considering these inclusion criteria: randomized clinical trial (RCT) that examines the efficacy of LLLT in rapid palatal expansion (RPE), age under 15 years, non-surgical RPE with a tooth-supported appliance, and low-intensity laser application. Finally, 4 articles were appraised by Cochrane version 5.2.0 with 7 domains. 3 of 4 articles showed LLLT has a significant impact on bone formation. One of them showed no significant difference in pain perception and bone density between the laser and non-laser groups. Conclusion: While many studies have assessed the effect of LLLT on bone formation in animal models, high-quality clinical trials are missing in this regard. The available clinical trials suggest a positive effect of LLLT on sutural bone formation after RPE.

Evaluating the Preemptive Analgesic Effect of Photo-biomodulation Therapy on Pain Perception During Local Anesthesia Injection in Children: A Split-mouth Triple-blind Randomized Controlled Clinical Trial

To evaluate the impact of photobiomodulation therapy (PBMT) on injection pain perception and compare it with a topical oral anesthetic gel. A total of 30 patients of six to nine years old seeking pulpotomy treatment of maxillary secondary primary molars of both sides were considered for this split-mouth triple-blind randomized clinical trial. On one side of the maxilla, the low-level-laser (diode laser, 808 nm, 250 mW; 16.25 J; 32.5 J/cm² ) was irradiated upon the buccal gingiva of the tooth, while a Benzocaine 20% topical anesthetic gel was applied on the other side. A gel with the same taste (strawberry) was applied for the placebo. The Wong-Baker Faces Pain Rating Scale was used to evaluate the injection pain and post-operation pain at two timestamps, one hour and 24 hours after treatment. Patients' heart rate was also evaluated. Paired-T, Wilcoxon-signed-rank test, McNemar and Friedman tests were used for statistical analyses. Results demonstrated that PBMT could significantly decrease the injection pain perception and heart rate alternations compared to the topical anesthetic gels (P=0.000). However, no significant differences were documented between the two methods concerning the 1hour (P=0.26) and 24-hours (P=1.00) post-operation pain. PBMT can be an effective non-pharmacological technique for controlling injection pain.