Incorporation of raloxifene-impregnated allograft around orthopedic titanium implants impairs early fixation but improves new bone formation

Enhancing Bone Repair: Impact of Raloxifene-Functionalized Cerabone® on Rat Calvarial Defects

Bone substitutes are commonly used in bone regeneration, and their functionalization with bioactive molecules can significantly enhance bone regeneration by directly influencing bone cells. This study aimed to evaluate the potential of raloxifene-functionalized Cerabone® (CB) for promoting bone repair and to highlight the implications in bone regeneration. The effectiveness of Cerabone® functionalized with raloxifene via sonication or gel delivery in promoting bone repair in rat calvaria defects was assessed. Ninety-six male rats with critical-sized calvarial defects were divided into six treatment groups (n = 16): COAG (spontaneous blood clot), CB (Cerabone®), CBS (Cerabone® sonicated alone), CBRS (Cerabone® with raloxifene sonicated), CBG (Cerabone® with gel vehicle), and CBRG (Cerabone® with 20% raloxifene gel). After 14 and 28 days, samples were analyzed using microtomography, histomorphometry, immunohistochemistry, and fluorescence techniques. Quantitative data were statistically analyzed, comparing each group to the control CB group with significance set at p < 0.05. Micro-CT analysis demonstrated a significant increase in bone volume in the CBRS, CBRG, and CBS groups at 28 days compared to the CB group (p < 0.05). Specifically, the mean bone volume percentages for the CBRS, CBRG, CBS, and CB groups were 21.18%, 17.51%, 13.18%, and 7.8%, respectively. Histomorphometry showed increased new bone formation in the CBRS and CBRG groups at both 14 and 28 days. Fluorescence analysis revealed a significantly higher daily mineral apposition rate in the CBRS and CBRG groups at 28 days. These findings suggest that raloxifene-functionalized CB, delivered via sonication or gel, significantly enhances bone repair by improving bone volume and mineralization, highlighting its potential as an effective strategy for bone regeneration.

The Interplay of Raloxifene and Sonochemical Bio-Oss in Early Maxillary Sinus Bone Regeneration: A Histological and Immunohistochemical Analysis in Rabbits

The study aimed to assess the efficacy of using Raloxifene with ultrasonic processing to enhance Bio-Oss®, a bone graft substitute, for maxillary sinus bone height reconstruction. A total of 24 rabbit maxillary sinuses were distributed into three groups, each receiving different treatments: Bio-Oss® only, sonicated Bio-Oss, and sonicated Bio-Oss® with Raloxifene. Surgical procedures and subsequent histomorphometric and immunohistochemistry analyses were conducted to evaluate the bone formation, connective tissue, and remaining biomaterial, as well as the osteoblastic differentiation and maturation of collagen fibers. Results indicated that the sonicated Bio-Oss® and Bio-Oss® groups showed similar histological behavior and bone formation, but the Raloxifene group displayed inflammatory infiltrate, low bone formation, and disorganized connective tissue. The statistical analysis confirmed significant differences between the groups in terms of bone formation, connective tissue, and remaining biomaterial. In conclusion, the study found that while sonicated Bio-Oss® performed comparably to Bio-Oss® alone, the addition of Raloxifene led to an unexpected delay in bone repair. The findings stress the importance of histological evaluation for accurate bone repair assessment and the necessity for further investigation into the local application of Raloxifene. Future research may focus on optimizing bone substitutes with growth factors to improve bone repair.

Expression of osteogenic markers after administration of selective estrogen receptor modulators during implant placement in the osteoporotic rat maxilla

PURPOSE

This study examined the effects of raloxifene during bone formation around the dental implant in the ovariectomy-induced osteoporotic rat maxilla.

METHODS

Fifty-four female 10-week-old Sprague-Dawley rats were divided into three groups (n = 18 each); sham-operated (control), ovariectomized (OVX), and ovariectomized and raloxifene-administered (RAL). Eight weeks after ovariectomy, both upper first molars were extracted, and implants were placed 4 weeks post-extraction. The RAL group was given 1 mg/kg of raloxifene per day while the other groups received a vehicle. Six rats in each group were sacrificed at days 4, 7, and 14 and submitted for quantitative reverse transcription polymerase chain reaction and immunohistochemical staining, for evaluation of osteogenic genes expressions.

RESULTS

The alkaline phosphatase expression was upregulated in the RAL group compared to the OVX group at day 4. The osteocalcin expression was significantly higher between the RAL group and the OVX group at day 7. Immunohistochemical staining revealed increased expression during the initial bone-forming process and indicated more active bone formation in the RAL group than in the OVX group.

CONCLUSION

Raloxifene administration enhanced the osteogenic genes and proteins expression in the bone around the implant. Further studies are required to establish the long-term clinical effects of raloxifene administration.