RESUMO
BACKGROUND: Orthodontic tooth movement (OTM) can be accelerated by increasing bone turnover. Carrageenan is a common food additive, which can induce inflammation. Hence, it might accelerate OTM. However, it has not been investigated to date. METHODS: This 2-phase preliminary animal experimental study was conducted on 28 Wistar rats. A pilot study on 5 mice was done to estimate the experimental dose of carrageenan. The first phase evaluated the effect of a 40µL carrageenan 1% injection on inflammation status in 7 rats versus 7 control rats, 6hours after the injection. The second phase examined the effect of the same dose of carrageenan on OTM speed during 21 days of incisor retraction in rat, in two groups: control (normal saline) and carrageenan (n=7×2). This sample size was pre-determined based on a priori power calculations. In phase II, osteoclastic activity was also evaluated, 21 days after the injection. The groups were compared statistically (α=0.05). RESULTS: Six hours after carrageenan injection, 1, 3, and 3 rats had inflammation scores of 3 to 1, respectively. Six hours after saline injection, 1 rat had a score of 1 and the remainder had no inflammation (P=0.0023, Mann-Whitney). Twenty-one days after saline and carrageenan injection, OTMs were 0.7±0.3 and 1.1±0.4mm, respectively, (P=0.053, Mann-Whitney). Twenty-one days after saline and carrageenan injection, mean osteoclast counts were, respectively, 4.87±1.849 and 7.143±1.727 per field (P=0.025, Mann-Whitney). CONCLUSION: Local injection of carrageenan can induce inflammation after 6hours. It can increase approximately 1.6-fold the speed of OTM, and increase the osteoclast count 1.5-fold after 21 days of space closure.
Assuntos
Remodelação Óssea/efeitos dos fármacos , Carragenina/administração & dosagem , Inflamação/induzido quimicamente , Técnicas de Movimentação Dentária/métodos , Animais , Injeções , Ratos , Ratos WistarRESUMO
OBJECTIVES: To evaluate comparatively the effect of quercetin on postbleaching shear bond strength (SBS) and adhesive remnant index (ARI). MATERIALS AND METHODS: Intact maxillary premolars were divided randomly into 12 groups of 10 each: (1) bonding the bracket immediately after bleaching, (2) bonding 1 week after bleaching, (3-8) application of three experimental concentrations of quercetin (0.1%, 0.5%, and 1%) at two time durations (5 and 10 min), (9-10) application of the solvent of quercetin at two time periods (5 and 10 min), (11) application of 10% sodium ascorbate for 10 min, and (12) bonding the brackets on nonbleached teeth. Bleaching was performed using 15% carbamide peroxide gel for 5 days (6 h daily). After incubation and thermocycling, the SBS of brackets was measured. The ARI too was recorded at ×20. The data were analyzed statistically (α =0.05). RESULTS: Bleaching reduced the SBS below 10 Megapascal (MPa) level (P < 0.05) while all the postbleaching treatments (except the application of the solvent of quercetin) recovered the SBS back to values greater than 10 MPa (P < 0.05) and also back to nonbleached SBS levels (P > 0.01). All eight postbleaching treatments had rather similar efficacies (P = 0.1396). The concentration of quercetin (beta = 0.259, P = 0.042) but not its duration (beta = 0.213, P = 0.093) significantly improved its efficacy. CONCLUSION: Bleaching can weaken the bond strength of orthodontic brackets below acceptable levels. The application of quercetin or Vitamin C or delaying the bracket bonding improved the postbleaching SBS.