Objective:Objective: Objective: Objective: To test the hypothesis that platelet rich plasma (PRP) injection can minimize relapse of orthodontically moved teeth. Material and Methods:Material and Methods: Material and Methods: Material and Methods: Thirty rabbits were randomly and equally divided into three groups (A, B and C). The mock group C (n=10) was further equally divided into C1 and C2 subgroups. A mesializing force was applied to the first molar on both sides in all groups. After achieving orthodontic movement, in groups A and B, (PRP) was injected on the experimental side while normal saline was injected on the control side. Animals in group C did not receive any injections. Animals in groups A and C1 were sacrificed after 1 week and animals in groups B and C2 were sacrificed after four weeks. Amount of first molar relapse in all groups was measured and compared. Results:Results: Results: Results: After 1 week and 4 weeks relapse periods; the distance of relapse in the experimental group was reduced significantly (P <0.001) when compared with the control and mock groups. No statistically significant difference was found between the relapse observed in the experimental groups in 1 week and 4 weeks relapse periods; (29.09%) and (39.16%) respectively. However, relapse increased significantly (P <0.001) in both the control and mock groups from 1 week
Objective: To test shear bond strength and mode of debonding of brackets bonded using a traditional orthodontic adhesive (Transbond XT), self-adhesive material (Heliosit) and selfetch &self-adhesive resin material (Vertise flow) with and without phosphoric acid etching; after 15 minutes, 24 hours and following aging and thermocycling. Materials and Methods: One hundred and eighty upper first premolar teeth were used in this study. The specimens were equally and randomly allocated into four groups. TXT group (Transbond XT; n=45); HS group (Heliosit group; n=45); VF group (Vertise Flow; n=45) and (VF+P) (Vertise Flow with phosphoric acid etch; n=45). Each group was randomly divided into three equal subgroups; First subgroup (n=15) shear bond strength was tested after 15 minutes of bracket bonding, second subgroup (n=15): shear bond strength was tested after storage in distilled water at 37°C for 24 hours and third subgroup (n=15): shear bond strength was tested after specimens storage in distilled water at 37°C for 6 weeks and subjected to 1000 thermal cycles. Adhesive remnant index (ARI) was recorded for each specimen and its mean was compared between different groups. Results: Vertise flow (either with or without enamel pre-etching) and Transbond had acceptable bond strength at 15minutes debond testing. Heliosit adhesive had a significantly lower SBS at 15 minutes debond. Transbond XT had a significantly higher (SBS) compared to the other 3 groups at 24 hours debond. Thermocycling and aging conditions affected SBS in all the groups except specimens bonded using Transbond XT. Vertise Flow when used without enamel pre-etch resulted in decreased SBS below the clinically acceptable value after thermocycling and aging. Conclusions: Both Vertise Flow (when used with pre-etched enamel) and Heliosit can be used in orthodontic practice, offering simplified bonding procedures associated with clinically acceptable bond strength and minimal amount of remaining adhesive on enamel surface at debond.
OBJECTIVE:To evaluate the shear bond strength (SBS) of ceramic brackets bonded to feldspathic porcelain using different bonding protocols. MATERIAL AND METHODS: 30 porcelain fused to metal (PFM) disks were fabricated and randomly divided into three equal groups of 10 each. Each group had a different surface treatment as follows:-Group A: air abrasion, etching with hydrofluoric acid (HF), silane and Reliance Assure Plus (RA plus). Group B: air abrasion, silane and RA Plus (manufacturer's recommendation). Group C: air abrasion and RA Plus. Ceramic brackets were bonded to PFM discs using light cure-composite resin. Following thermocycling, SBS was measured using a universal testing machine. After bracket debonding, Failure mode was measured under stereomicroscope. RESULTS: Group A and group B showed the highest SBS value with a mean of 8.86 ± 1.99 and 10.32 ± 4.39 MPa respectively with no statistically significant difference among them. However, group C showed statistically significant lower SBS with a mean value of 1.84 ± 0.74 Mpa. Failure modes of groups A and B were predominantly at the adhesive / bracket interface. Meanwhile, group C showed mixed adhesive / porcelain interface and cohesive resin failure. CONCLUSION: Air abrasion and silane resulted in clinically acceptable bond strength among the groups regardless the use of HF. Silane appears to be integral in achieving adequate bond strength. The universal primer used in the current study can not be used as a substitute to silane.
of upper anterior teeth is a common method for sliding mechanics tooth movement. Predictable tooth movement requires that the force vector passes through the center of resistance of upper maxillary teeth. Materials and methods: This randomized clinical trial was carried on female patients in need of extraction of at least of two maxillary first premolars. The sample was separated into three groups; Group I: study group with Anterior retraction hook (ARH) of 9 mm, group II: study group with ARH of 6 mm, group III: study group with ARH of 3mm. Cone beam computed tomography were taken at two-time intervals for the whole sample; T1: Before the onset of en-masse retraction and T2: At the end of en-masse retraction. Results: Significant reduction in the inclination of anterior teeth as measured to the palatal plane had been recorded in three groups. Significant retraction of crowns and roots of anterior teeth had been recorded in all groups. Significantly lower amount of root movement had been recorded in group 2 and 3 compared to group 1. All groups showed statistically significant intrusive movement with significantly less intrusion movement in group 2 and group 3 relative to group 1. Conclusions: Bodily movement is possible during enmasse retraction if the force vector passes through the center of resistance of anterior teeth. Increasing length of ARH decrease amount of uncontrolled tipping during en-masse retraction with more intrusive effect on the anterior teeth.
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