Does hormone replacement therapy impact implant osseointegration in females- A systematic review and meta-analysis

Background

This review aimed to comprehensively investigate the impact of Hormone Replacement Therapy (HRT) on implant osseointegration and bone loss. The study considered factors such as HRT type, osteoporosis, smoking, and diabetes mellitus, and analysed the available literature to provide insights into the association between HRT and implant outcomes.

Methods

Multiple databases were utilized, and studies with diverse designs and methodologies were included that examined the relationship between HRT and implant osseointegration. The selected studies were analyzed and relevant data on implant success rates, bone loss, and other correlations was extracted.

Results

The review findings indicate that HRT has a detrimental impact on implant osseointegration, as evidenced by lower implant success rates and increased bone loss in HRT-treated individuals. The odds ratio analysis further strengthens this association, with significant values of 0.59 (95% CI: 0.50-0.70) and 0.64 (95% CI: 0.54-0.76), indicating a higher likelihood of implant failure in HRT-treated patients., highlighting the need for caution when considering HRT as a treatment option in patients undergoing implant procedures. Smoking and diabetes mellitus were also found to significantly affect implant outcomes, emphasizing the importance of addressing these factors in patient management.

Conclusion

The assessments demonstrate that HRT adversely affects implant osseointegration and increases bone loss. The results suggest the importance of considering the potential negative impact of HRT on implant outcomes and the need for thorough patient evaluation and management. Further research is warranted to explore the underlying mechanisms, assess the impact of specific HRT types and dosages, and evaluate preventive strategies to mitigate the detrimental effects of HRT on implant success.

Construction of multifunctional coating with cationic amino acid-coupled peptides for osseointegration of implants

Osseointegration is an important indicator of implant success. This process can be improved by coating modified bioactive molecules with multiple functions on the surface of implants. Herein, a simple multifunctional coating that could effectively improve osseointegration was prepared through layer-by-layer self-assembly of cationic amino acids and tannic acid (TA), a negatively charged molecule. Osteogenic growth peptide (OGP) and the arginine-glycine-aspartic acid (RGD) functional polypeptides were coupled with Lys6 (K6), the two polypeptides then self-assembled with TA layer by layer to form a composite film, (TA-OGP@RGD)n. The surface morphology and biomechanical properties of the coating were analyzed in gas and liquid phases, and the deposition process and kinetics of the two peptides onto TA were monitored using a quartz crystal microbalance. In addition, the feeding consistency and adsorption ratios of the two peptides were explored by using fluorescence visualization and quantification. The (TA-OGP@RGD)n composite membrane mediated the early migration and adhesion of cells and significantly promoted osteogenic differentiation and mineralization of the extracellular matrix in vitro. Additionally, the bifunctional peptide exhibited excellent osteogenesis and osseointegration owing to the synergistic effect of the OGP and RGD peptides in vivo. Simultaneously, the (TA-OGP@RGD)n membrane regulated the balance of reactive oxygen species in the cell growth environment, thereby influencing the complex biological process of osseointegration. Thus, the results of this study provide a novel perspective for constructing multifunctional coatings for implants and has considerable application potential in orthopedics and dentistry.

Semaphorin3A promotes osseointegration of titanium implants in osteoporotic rabbits

OBJECTIVE

In the present study, we intend to assess the function of Sema3A in osteointegration of titanium implants both in vivo and in vitro.

MATERIAL AND METHODS

Briefly, Sema3A was transfected in HBMSCs cells to detect its effect on osteogenesis. Subsequently, an in vivo rabbit model was established. Eighteen female rabbits were randomly assigned into three groups (n=6), and rabbits in the two treatment groups (OVX groups) were subjected to bilateral ovariectomy, while those in the control group were treated with sham operation. Twelve weeks later, we first examined expression levels of Sema3A in rabbits of the three groups. Titanium implants were implanted in rabbit proximal tibia. Specifically, rabbits in sham group were implanted with Matrigel, while the remaining in the OVX experimental group (OVX+Sema3A group) and OVX group were implanted with Matrigel containing Sema3A adeno-associated virus or empty vector, respectively.

RESULTS

Histomorphometry results uncovered that rabbits in the OVX+Sema3A group had a significantly higher BIC compared with those of the OVX group on the 12th week of post-implantation. And compared with the OVX group, the maximum push-out force increased by 89.4%, and the stiffness increased by 39.4%, the toughness increased by 63.8% in the OVX+Sema3A group at 12 weeks.

CONCLUSION

Sema3A has a positive effect on promoting early osseointegration of titanium implants in osteoporotic rabbits.

CLINICAL RELEVANCE

Our research found that Sema3A can improve the osteogenic ability of bone marrow stem cells and promotes osseointegration during osteoporosis.

Photobiomodulation (450 nm) alters the infection of periodontitis bacteria via the ROS/MAPK/mTOR signaling pathway

We aimed to investigate the effects of photobiomodulation (PBM) on periodontitis. A periodontitis model was established via Porphyromonas gingivalis infection in beagles. Mandibular second and third premolars were removed, and implants were positioned immediately after tooth extraction. Left gingiva was irradiated with PBM (450 nm) as the LG group, and right side without irradiation was regarded as the CG (control) group. PBM treatment increased oxidative stress by increasing the levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The elevated levels of H₂O₂ (a biomarker of oxidative stress) and the free radicals (NO^• and O₂^•-) reduced the concentration of dominant pathogens and regulated ROS/RNS/AMP-activated protein kinase (AMPK)/mTOR pathway by affecting p-AMPK, Runt-related transcription factor 2 (RUNX2), p-c-Jun N-terminal kinase (JNK)/mammalian target of rapamycin (mTOR), and acetyl-CoA carboxylase 1 (ACC1). PBM therapy increased salivary levels of interleukin-1 receptor antagonist (IL-1ra), interleukin (IL)-10, total antioxidant capacity (TAC) and catalase (CAT), and reduced the levels of tumor necrosis factor (TNF)α and interleukin (IL)-1β, malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-OHdG) (p < 0.05). All the results contributed to preventing periodontitis infection. PBM therapy improved bone mineral density and implant osseointegration by controlling dominant pathogens invasion via the upregulation of salivary anti-inflammatory and antioxidant defense by affecting ROS/RNS/AMPK/mTOR signaling pathway.

Pulsed electromagnetic fields modify the adverse effects of glucocorticoids on bone architecture, bone strength and porous implant osseointegration by rescuing bone-anabolic actions

Long-term glucocorticoid therapy is known to induce increased bone fragility and impaired skeletal regeneration potential. Growing evidence suggests that pulsed electromagnetic fields (PEMF) can accelerate fracture healing and increase bone mass both experimentally and clinically. However, how glucocorticoid-treated bone and bone cells respond to PEMF stimulation remains poorly understood. Here we tested the effects of PEMF on bone quantity/quality, bone metabolism, and porous implant osseointegration in rabbits treated with dexamethasone (0.5 mg/kg/day, 6 weeks). The micro-CT, histologic and nanoindentation results showed that PEMF ameliorated the glucocorticoid-mediated deterioration of cancellous and cortical bone architecture and intrinsic material properties. Utilizing the new porous titanium implant (Ti2448) with low toxicity and low elastic modulus, we found that PEMF stimulated bone ingrowth into the pores of implants and enhanced peri-implant bone material quality during osseous defect repair in glucocorticoid-treated rabbits. Dynamic histomorphometric results revealed that PEMF reversed the adverse effects of glucocorticoids on bone formation, which was confirmed by increased circulating osteocalcin and P1NP. PEMF also significantly attenuated osteocyte apoptosis, promoted osteoblast-related osteocalcin, Runx2 and Osx expression, and inhibited osteocyte-specific DKK1 and Sost expression (negative regulators of osteoblasts) in glucocorticoid-treated skeletons, revealing improved functional activities of osteoblasts and osteocytes. Nevertheless, PEMF exerted no effect on circulating bone-resorbing cytokines (serum TRAcP5b and CTX-1) or skeletal gene expression of osteoclast-specific markers (TRAP and cathepsin K). PEMF also significantly upregulated skeletal gene expression of canonical Wnt ligands (Wnt1, Wnt3a and Wnt10b), whereas PEMF did not alter non-canonical Wnt5a expression. This study demonstrates that PEMF treatment improves bone mass, strength and porous implant osseointegration in glucocorticoid-treated rabbits by promoting potent bone-anabolic action, which is associated with canonical Wnt-mediated improvement in osteoblast and osteocyte functions. This study provides a new treatment alternative for glucocorticoid-related bone disorders in a convenient and non-invasive manner.

Staged implant placement after defect regeneration using biphasic calcium phosphate materials with different surface topographies in a minipig model

OBJECTIVE

To assess the influence of biphasic calcium phosphate materials with different surface topographies on bone formation and osseointegration of titanium implants in standardized alveolar ridge defects.

MATERIALS AND METHODS

Standardized alveolar ridge defects (6 × 6 mm) were created in the mandible of 8 minipigs and filled with three biphasic calcium phosphate materials (BCP1-3, 90% tricalcium phosphate/10% hydroxyapatite) with different surface properties (micro- and macroporosities) as well as a bovine-derived natural bone mineral (NBM) as a control. At 12 weeks, implants were placed into the augmented defects. After further 8 weeks of healing, dissected blocks were processed for histological analysis (e.g., mineralized (MT), residual bone graft material (BS), bone-to-implant contact (BIC)).

RESULTS

All four biomaterials showed well-integrated graft particles and new bone formation within the defect area. MT values were comparable in all groups. BS values were highest in the NBM group (21.25 ± 13.52%) and markedly reduced in the different BCP groups, reaching statistical significance at BCP1-treated sites (9.2 ± 3.28%). All test and control groups investigated revealed comparable and statistically not significant different BIC values, ranging from 73.38 ± 20.5% (BCP2) to 84.11 ± 7.84% (BCP1), respectively.

CONCLUSION

All bone graft materials facilitated new bone formation and osseointegration after 12 + 8 weeks of healing.

In vivo monitoring of bone architecture and remodeling after implant insertion: The different responses of cortical and trabecular bone

The mechanical integrity of the bone-implant system is maintained by the process of bone remodeling. Specifically, the interplay between bone resorption and bone formation is of paramount importance to fully understand the net changes in bone structure occurring in the peri-implant bone, which are eventually responsible for the mechanical stability of the bone-implant system. Using time-lapsed in vivo micro-computed tomography combined with new composite material implants, we were able to characterize the spatio-temporal changes of bone architecture and bone remodeling following implantation in living mice. After insertion, implant stability was attained by a quick and substantial thickening of the cortical shell which counteracted the observed loss of trabecular bone, probably due to the disruption of the trabecular network. Within the trabecular compartment, the rate of bone formation close to the implant was transiently higher than far from the implant mainly due to an increased mineral apposition rate which indicated a higher osteoblastic activity. Conversely, in cortical bone, the higher rate of bone formation close to the implant compared to far away was mostly related to the recruitment of new osteoblasts as indicated by a prevailing mineralizing surface. The behavior of bone resorption also showed dissimilarities between trabecular and cortical bone. In the former, the rate of bone resorption was higher in the peri-implant region and remained elevated during the entire monitoring period. In the latter, bone resorption rate had a bigger value away from the implant and decreased with time. Our approach may help to tune the development of smart implants that can attain a better long-term stability by a local and targeted manipulation of the remodeling process within the cortical and the trabecular compartments and, particularly, in bone of poor health.