RESUMEN
BACKGROUND: Orthodontic relapse is a frequent problem that many patients experience. Although orthodontic therapy has advanced, recurrence rates can still reach 90%. We undertook a study to look at the possibilities of laser bio-stimulation and stem cells because they have showed promising outcomes in lowering recurrence rates. OBJECTIVES: Our objective was to analyze the effects of Low-level laser therapy (LLLT) and Mesenchymal stem cells (MSC) alone and collectively on the rate of orthodontic relapse in rats radiographically and histologically. METHODS: Rat maxillary central incisors were moved distally for two weeks. One week later, the incisors were retained. Animals (n = 40) were split into four groups. Control group (C); laser treatment Group (L), Bone marrow mesenchymal stem cells Group (BMSCs) and combination of Stem cells and laser-irradiation group (BMSCs-L). Removed retainer permitted relapse. Before stem cell application or laser irradiation, each animal underwent two CBCT scans. Rat maxillae were stained with Hx&E, Masson trichrome, and tartrate-resistant acid phosphatase antibody for histology, histochemistry, and immunohistochemistry. RESULTS AND CONCLUSIONS: LLLT could reduce the relapse tendency, as shown by increased bone density and enhanced remodeling of hetero-formed periodontal ligament (PDL). Furthermore, the transfer of BMMSCs on the pressure side had positive effects on PDL remodeling and decreased, but did not inhibit, the relapse rate. Finally, the synergistic effects of the application of LLLT and BMMSC were better than the control but still moderate and long-lasting. CLINICAL SIGNIFICANCE: Based on the improved relapse rate as proven in the present study, the Application of both LLLT and stem cells can be adopted to reduce the relapse tendency either lonely or collectively.
RESUMEN
AIM: The objectives of this clinical study were as follows: (i) to determine the effect of frequency of calcium hydroxide [Ca(OH)(2)] dressing change on the apical barrier formation in immature permanent incisors with necrotic pulps and (ii) to investigate the effect of various clinical factors before and during treatment that may be associated with the frequency of Ca(OH)(2) dressing changes. METHODS: The study involved 21 healthy subjects, 8-12 years old. Twenty-three immature traumatized permanent maxillary central incisors were treated using Ca(OH)(2) powder mixed with barium sulfate and distilled water. The progress of barrier formation was reviewed after 6 months of first placement of Ca(OH)(2) and then every 3 months until the detection of an apical barrier. Clinical and radiographic evaluations were performed before and after treatment. Data were evaluated using a chi-square test. RESULTS: Apical barrier formation was successful for all 23 teeth. Seventeen teeth (74%) needed only a single application of Ca(OH)(2), while six teeth (26%) required more than one application. The average time of apical barrier formation was 30 weeks, and the mean number of Ca(OH)(2) dressing changes was 1.3. A significant positive association was found between teeth that presented with displacement and the number of Ca(OH)(2) dressing changes (P = 0.004). CONCLUSION: An initial 6-month application of Ca(OH)(2) dressing followed by 3-month replacements (usually in teeth presenting with displacement and/or sinus tracts) may be successfully used in apexification treatment. This would assist in reducing the number of Ca(OH)(2) dressing changes, number of appointments, cost of treatment and radiation exposure.