RESUMEN
This study evaluated the bone incorporation process of a screw-shaped internal fixation device made of poly (L-lactide-co-D, L-lactide) (PLDLLA). Thirty-two male Wistar rats received 32 fixation devices (2 mm × 6 mm) randomly assigned to either the right or left tibia and one implant in each animal. After 7, 14, 28, and 42 days, the rats were euthanized and the specimens were subjected to microtomographic computed tomography (microCT) and histomorphometric analyses to evaluate bone interface contact (BIC%) and new bone formation (NBF%) in cortical and cancellous bone areas. The animals euthanized on days 28 and 42 were treated with calcein and alizarin red, and confocal LASER microscopy was performed to determine the mineral apposition rate (MAR). Micro-CT revealed a higher percentage of bone volume (p < 0.006), trabecular separation (p < 0.001), and BIC in the cortical (p < 0.001) and cancellous (p = 0.003) areas at 28 and 42 days than at 7 and 14 days. The cortical NBF at 42 days was greater than that at 7 and 14 days (p = 0.022). No statistically significant differences were observed in cancellous NBF or MAR at 28 and 42 days. Based on these results, it can be seen that the PLDLLA internal fixation device is biocompatible and allows new bone formation around the screw thread.
RESUMEN
(1) Objective: The aim of this study was to assess the biological behavior of bone tissue on a machined surface (MS) and modifications made by a laser beam (LS) and by a laser beam incorporated with hydroxyapatite (HA) using a biomimetic method without thermic treatment (LHS). (2) Methods: Scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM/EDX) was performed before and after installation in the rabbit tibiae. A total of 20 Albinus rabbits randomly received 30 implants of 3.75 × 10 mm in the right and left tibias, with two implants on each surface in each tibia. In the animals belonging to the 4-week euthanasia period group, intramuscular application of the fluorochromes calcein and alizarin was performed. In implants placed mesially in the tibiofemoral joint, biomechanical analysis was performed by means of a removal torque (N/cm). The tibias with the implants located distally to the joint were submitted for analysis by confocal laser microscopy (mineral apposition rate) and for histometric analysis by bone contact implant (%BIC) and newly formed bone area (%NBA). (3) Results: The SEM showed differences between the surfaces. The biomechanical analysis revealed significant differences in removal torque values between the MSs and LHSs over a 2-week period. Over a 4-week period, both the LSs and LHSs demonstrated removal torque values statistically higher than the MSs. BIC of the LHS implants were statistically superior to MS at the 2-week period and LHS and LS surfaces were statistically superior to MS at the 4-week period. Statistical analysis of the NBA of the implants showed difference between the LHS and MS in the period of 2 weeks. (4) Conclusions: The modifications of the LSs and LHSs provided important physicochemical modifications that favored the deposition of bone tissue on the surface of the implants.
RESUMEN
OBJECTIVE: This study aimed to evaluate the efficacy of ozone therapy in the preoperative (prevention) and/or postoperative (treatment) of MRONJ. MATERIAL AND METHODS: Forty male Wistar rats were caudally treated with zoledronic acid (ZOL) and to ozone therapy before extraction (prevention, POG), after extraction (treatment, TOG), or both (prevention and treatment, TPOG), and treated with saline (SAL). The animals received intramuscular fluorochrome (calcein and alizarin), and 28 days postoperatively, they were euthanized, and the tissues were subjected to microtomographic computed tomography (microCT), LASER confocal, and histomorphometric analyses. RESULTS: Micro-CT showed a higher bone volume fraction average in all groups than that in the ZOL group (P < 0.001), the ZOL group showed high porosity (P = 0.03), and trabecular separation was greater in the TOG group than in the POG group (P < 0.05). The mineral apposition rate of the POG group was high (20.46 ± 6.31) (P < 0.001), followed by the TOG group (20.32 ± 7.4). The TOG group presented the highest mean newly formed bone area (68.322 ± 25.296) compared with the ZOL group (P < 0.05), followed by the SAL group (66.039 ± 28.379) and ZOL groups (60.856 ± 28.425). CONCLUSIONS: Ozone therapy modulated alveolar bone repair in animals treated with ZOL, mainly after surgery trauma, leading to bone formation as healing tissue. CLINICAL RELEVANCE: Osteonecrosis has been a challenge in dentistry, and owing to the lack of a consensus regarding therapy, studies presenting new therapies are important, and ozone has been one of the therapies explored empirically.