Alveolar bone healing in rats: micro-CT, immunohistochemical and molecular analysis

Systemic ozone therapy as an adjunctive treatment in guided bone regeneration: a histomorphometrical and immunohistochemical study in rats

OBJECTIVES

To assess the effectiveness of ozone therapy in guided bone regeneration (GBR) for critical size calvarial defects in rats.

MATERIALS AND METHODS

96 male Wistar rats were divided into four groups (n = 6 each). An 8 mm critical defect was created in the calvaria of each rat. The groups were: BIO (porcine collagen membrane, BioGide®), BIO + OZ (membrane with systemic ozone therapy every 2 days), COA + OZ (blood clot with ozone therapy), and COA (blood clot only). Evaluations at 7, 15, 30, and 60 days included histological, histomorphometric, inflammatory profile, Micro-CT, and immunohistochemical analyses. Statistical analysis involved two-factor ANOVA with Tukey's post-hoc test for general data, and one-factor ANOVA with Holm-Sidak post-hoc test for Micro-CT data.

RESULTS

The BIO + OZ group demonstrated superior bone regeneration with well-organized, mature bone tissue and significant bone formation at 30 and 60 days. The COA + OZ group showed early angiogenesis and reduced inflammation, resulting in complete defect closure by 30 days. The BIO group had good regeneration, but less mature tissue compared to BIO + OZ. The COA group exhibited limited bone formation and higher porosity.

CONCLUSION

Ozone therapy positively influences bone regeneration by enhancing cell proliferation and the healing response.

CLINICAL RELEVANCE

Improving regenerative processes with auxiliary therapies like ozone therapy can be significant for advancing dental reconstructions.

Regeneration of Critical Calvarial Bone Defects Using Bovine Xenograft, Magnesium-Enriched Bovine Xenograft and Autologous Dentin in Rats: Micro-CT, Gene Expression and Immunohistochemical Analysis

The aim of this study was to evaluate the efficacy of autologous dentin (AD), bovine xenograft (BX) and magnesium-enriched bovine xenograft (BX + Mg) in the healing of critical cranial bone defects (CCBDs) in rats. Eighty male Wistar rats were divided into four groups: BX, BX + Mg, AD and the control group (no intervention). Eight mm CCBDs were created and treated with the respective biomaterials. Healing was assessed 7, 15, 21 and 30 days after surgery by micro-computed tomography (micro-CT), real-time polymerase chain reaction (RT-PCR) and immunohistochemical analysis. Micro-CT analysis showed that AD had the highest bone volume and the least amount of residual biomaterial at day 30, indicating robust bone formation and efficient resorption. BX + Mg showed significant bone volume but had more residual biomaterial compared to AD. RT-PCR showed that the expression of osteocalcin (OC), the receptor activator of nuclear factor κB (RANK) and sclerostin (SOST), was highest in the AD group at day 21 and vascular endothelial growth factor (VEGF) at day 15, indicating increased osteogenesis and angiogenesis in the AD group. Immunohistochemical staining confirmed intense BMP-2/4 and SMAD-1/5/8 expression in the AD group, indicating osteoinductive properties. The favorable gene expression profile and biocompatibility of AD and BX + Mg make them promising candidates for clinical applications in bone tissue engineering. Further research is required to fully exploit their potential in regenerative surgery.

Effectiveness of the Association of Fibrin Scaffolds, Nanohydroxyapatite, and Photobiomodulation with Simultaneous Low-Level Red and Infrared Lasers in Bone Repair

Biomaterials and biopharmaceuticals for correcting large bone defects are a potential area of translational science. A new bioproduct, purified from snake venom and fibrinogen from buffalo blood, aroused interest in the repair of venous ulcers. Expanding potential uses, it has also been used to form biocomplexes in combination with bone grafts, associated with physical therapies or used alone. The aim of this preclinical study was to evaluate low-level laser photobiomodulation (PBM) in critical defects in the calvaria of rats filled with nanohydroxyapatite (NH) associated with the heterologous fibrin biopolymer (HFB). Sixty animals were used, divided into six groups (n = 10 each): G1 (NH); G2 (HFB); G3 (NH + HFB); G4 (NH + PBM); G5 (HFB + PBM); G6 (NH + HFB + PBM). PBM simultaneously used red (R) and infrared (IR) light emission, applied intraoperatively and twice a week, until the end of the experiment at 42 days. Microtomography, bone formation can be seen initially at the margins of the defect, more evident in G5. Microscopically, bone formation demonstrated immature and disorganized trabeculation at 14 days, with remnants of grafting materials. At 42 days, the percentage of new bone formed was higher in all groups, especially in G5 (HFB, 45.4 ± 3.82), with collagen fibers at a higher degree of maturation and yellowish-green color in the birefringence analysis with Picrosirius-red. Therefore, it is concluded that the HFB + PBM combination showed greater effectiveness in the repair process and presents potential for future clinical studies.

Efficacy and safety of a new heterologous fibrin biopolymer on socket bone healing after tooth extraction: An experimental pre-clinical study

AIM

To assess the efficacy of heterologous fibrin biopolymer (HFB) in promoting alveolar bone healing after tooth extraction in rats.

MATERIALS AND METHODS

The upper right incisors of 48 Wistar rats were extracted. Toothless sockets were filled with HFB (HFBG, n = 24) or blood clot (BCG, n = 24). The tooth extraction sites were subjected to micro-computed tomography (micro-CT), histological, histomorphometric and immunohistochemical (for Runt-related transcription factor 2/Runx2 and tartrate-resistant acid phosphatase/TRAP) analyses on days 0, 7, 14 and 42 after extraction.

RESULTS

Socket volume remained similar between days 0 and 14 (69 ± 5.4 mm3), except in the BCG on day 14, when it was 10% lower (p = .043). Although the number of Runx2+ osteoblasts was high and similar in both groups (34 × 102 cells/mm2), the HFBG showed lower inflammatory process and osteoclast activity than BCG at 7 days. On day 14, the number of Runx2+ osteoblasts remained high and similar to the previous period in both groups. However, osteoclast activity increased. This increase was 55% lower in the HFBG than BCG. In the BCG, the presence of an inflammatory process and larger and numerous osteoclasts on day 14 led to resorption of the alveolar bone ridge and newly formed bone. On day 42, numbers of Runx2+ osteoblast and TRAP+ osteoclasts decreased dramatically in both groups. Although the BCG exhibited a more mature cortical bone formation, it exhibited a higher socket reduction (28.3 ± 6.67%) and smaller bone volume (37 ± 5.8 mm3) compared with HFBG (socket reduction of 14.8 ± 7.14% and total bone volume of 46 ± 5.4 mm3).

CONCLUSIONS

HFB effectively suppresses osteoclast activity and reduces alveolar bone resorption compared with blood clot, thus preventing three-dimensional bone loss, particularly during the early healing period. HFB emerges as a promising biopharmaceutical material for enhancing healing processes after tooth extraction.

Inflammatory Profile of Different Absorbable Membranes Used for Bone Regeneration: An In Vivo Study

BACKGROUND

Guided bone regeneration (GBR) has become a necessary practice in implantology. Absorbable membranes have shown advantages over non-absorbable membranes, such as blood support of bone tissue. This study aimed to evaluate five collagen membranes in rat calvaria critical-size defects through a histomorphometric analysis of the inflammatory profile during the initial phase of bone repair.

MATERIALS AND METHODS

A total of 72 Albinus Wistar rats were used for the study, divided into six groups, with 12 animals per group, and two experimental periods, 7 and 15 days. The groups were as follows: the CG (clot), BG (Bio-Gide®), JS (Jason®), CS (Collprotect®), GD (GemDerm®), and GDF (GemDerm Flex®).

RESULTS

Data showed that the BG group demonstrated an inflammatory profile with an ideal number of inflammatory cells and blood vessels, indicating a statistically significant difference between the JS and CS groups and the BG group in terms of the number of inflammatory cells and a statistically significant difference between the JS and CS groups and the GD group in terms of angiogenesis (p < 0.05).

CONCLUSIONS

We conclude that different origins and ways of obtaining them, as well as the thickness of the membrane, can interfere with the biological response of the material.

The Addition of Hydroxyapatite Nanoparticles on Implant Surfaces Modified by Zirconia Blasting and Acid Etching to Enhance Peri-Implant Bone Healing

This study investigated the impact of adding hydroxyapatite nanoparticles to implant surfaces treated with zirconia blasting and acid etching (ZiHa), focusing on structural changes and bone healing parameters in low-density bone sites. The topographical characterization of titanium discs with a ZiHa surface and a commercially modified zirconia-blasted and acid-etched surface (Zi) was performed using scanning electron microscopy, profilometry, and surface-free energy. For the in vivo assessment, 22 female rats were ovariectomized and kept for 90 days, after which one implant from each group was randomly placed in each tibial metaphysis of the animals. Histological and immunohistochemical analyses were performed at 14 and 28 days postoperatively (decalcified lab processing), reverse torque testing was performed at 28 days, and histometry from calcified lab processing was performed at 60 days The group ZiHa promoted changes in surface morphology, forming evenly distributed pores. For bone healing, ZiHa showed a greater reverse torque, newly formed bone area, and bone/implant contact values compared to group Zi (p < 0.05; t-test). Qualitative histological and immunohistochemical analyses showed higher features of bone maturation for ZiHa on days 14 and 28. This preclinical study demonstrated that adding hydroxyapatite to zirconia-blasted and acid-etched surfaces enhanced peri-implant bone healing in ovariectomized rats. These findings support the potential for improving osseointegration of dental implants, especially in patients with compromised bone metabolism.

Evaluation of Porcine Collagen Membranes Used with Guided Bone Regeneration for Critical Defects: A Histological, Histomorphometric, Immunohistochemical, and Inflammatory Profile Analysis

OBJECTIVE

 The objective of this study was to compare the effectiveness of two porcine collagen membranes of different origin used for guided bone regeneration procedures.

MATERIALS AND METHODS

 Resorbable collagen membrane from porcine dermis (Bio-Gide, Geistlich Pharma AG, Wolhusen, Switzerland) and resorbable collagen membrane from porcine pericardium (Jason, Institut Straumann AG, Peter Merian-Weg, Switzerland) were evaluated; histological, histometric, immunohistochemical, and inflammatory profile analyses were performed. The study was carried out on critical defects created in the calvaria of 72 rats (Rattus norvegicus albinus, Wistar variety) divided into three groups: coagulum group (Co), porcine pericardium group (JS), and porcine collagen group (BG). The defects were filled with clot, over which the membranes were placed. The animals were euthanized 7, 15, 30, and 60 days after surgery.

STATISTICAL ANALYSIS

 The Shapiro-Wilk test was used to assess data distribution. Analysis of variance (ANOVA) and the Bonferroni multiple comparison test were used to compare the differences across the mean values of the variables. Nonparametric tests, Mann-Whitney and Wilcoxon W, were used for the quantitative analysis of the inflammatory profile. A significance level of 5% (p < 0.05) was adopted with a confidence interval of 95%. SPSS software version 2.0 was used.

RESULTS

 A total of 1,008 analyses were performed on 288 histological slides. It was noted that both types of collagen membranes used in this study were effective for the guided bone regeneration procedure, with a greater proportion and thickness of bone formation among recipients of the BG (735 points, p = 0.021). This membrane also had greater permeability (62.25). The animals in the JS group, which received the porcine pericardial membrane, showed early and accelerated bone formation from early bone tissue, milder osteopontin and osteocalcin levels, and greater inflammatory reaction (86.4).

CONCLUSION

 The collagen membrane from porcine dermis demonstrated a more orderly and physiological repair process, while the porcine pericardial membrane presented a more accelerated repair process that did not remain constant over time.

Fish scale-derived hydroxyapatite for alveolar ridge preservation

Alveolar ridge resorption following tooth extraction poses significant challenges for future dental restorations. This study investigated the efficacy of fish scale-derived hydroxyapatite (FSHA) as a socket preservation graft material to maintain alveolar bone volume and architecture. FSHA was extracted from *Labeo rohita* fish scales and characterized using Fourier transform infrared (FTIR) analysis. In vitro, biocompatibility and osteogenic potential were assessed using Saos-2 human osteosarcoma cells. Cell viability, migration, and proliferation were evaluated using MTT and scratch assays. In vivo performance was assessed in a rat model, and FSHA was compared to a commercial xenograft (Osseograft) and ungrafted controls. Histological analysis was performed at 8-week post-implantation to quantify new bone formation. FTIR confirmed the purity and homogeneity of FSHA. In vitro, FSHA enhanced Saos-2 viability, migration, and proliferation compared to controls. In vivo, FSHA demonstrated superior bone regeneration compared to Osseograft and ungrafted sites, with balanced graft resorption and new bone formation. Histological analysis revealed an active incorporation of FSHA into new bone, with minimal gaps and ongoing remodeling. Approximately 50%-60% of FSHA was resorbed by 8 weeks, closely matching the rate of new bone deposition. FSHA stimulated more bone formation in the apical socket region than in coronal areas. In conclusion, FSHA is a promising biomaterial for alveolar ridge preservation, exhibiting excellent biocompatibility, osteogenic potential, and balanced resorption. Its ability to promote robust bone regeneration highlights its potential as an effective alternative to currently used graft materials in socket preservation procedures.

Learn, unlearn, and relearn post-extraction alveolar socket healing: Evolving knowledge and practices

OBJECTIVE

This review was to offer a comprehensive analysis of currently available evidence on post-extraction alveolar socket healing, including i) the histological and molecular events during alveolar socket healing, ii) the dimensional ridge alterations after socket healing and controversies relating to sinus pneumatisation, iii) the patient-specific factors, procedural elements, and site-related variables influencing socket healing, iv) techniques and effectiveness of alveolar ridge preservation (ARP) procedure, and v) the philosophies and cost-effectiveness of ARP in clinical practice.

SOURCES AND STUDY SELECTION

To investigate the dimensional profiles of the alveolar ridge following unassisted healing, an overview of systematic reviews was conducted in February 2024 by two independent reviewers. Four electronic databases were searched in Pubmed, Embase, Web of science and Cochrane Library between 2004 and 2024 to identify all relevant systematic reviews on post-extraction healing. A further manual search of reviews was also conducted. The articles were further reviewed in full text for relevance. The AMSTAR-2 appraisal tool was adopted to assess methodological quality. Current research pertaining to other listed objectives was objectively analysed in narration.

DATA

11 out of 459 retrieved studies were selected and ultimately covered in this review on the dimensional changes of alveolar ridge following natural healing: Seven systematic reviews and four systematic reviews with meta-analyses. The methodological quality of all included reviews was critically low.

CONCLUSION

This review thoroughly examines the healing profiles of post-extraction alveolar sockets and highlights the dynamic process with overlapping phases and the inter-individual variability in outcomes. ARP procedure is a potential strategy for facilitating prosthetic site development, while the current evidence is limited. Herein, an individualised and prosthetically driven approach is crucial. Further well sized and designed trials with novel biomaterials need to be undertaken, and the role of artificial intelligence in predicting healing and assisting clinical decision-making could be explored.

CLINICAL SIGNIFICANCE

By advancing our understanding of alveolar socket healing and its management strategies, clinicians can make more informed decisions regarding patient and site level assessment and selection, surgical techniques, and biomaterial choices, ultimately contributing to the enhanced healing process with reduced complications and improved quality of life for patients undergoing tooth extraction and dental implant treatments.

Combination of a Synthetic Bioceramic Associated with a Polydioxanone-Based Membrane as an Alternative to Autogenous Bone Grafting

The purpose of this study was to evaluate the repair process in rat calvaria filled with synthetic biphasic bioceramics (Plenum® Osshp-70:30, HA:βTCP) or autogenous bone, covered with a polydioxanone membrane (PDO). A total of 48 rats were divided into two groups (n = 24): particulate autogenous bone + Plenum® Guide (AUTOPT+PG) or Plenum® Osshp + Plenum® Guide (PO+PG). A defect was created in the calvaria, filled with the grafts, and covered with a PDO membrane, and euthanasia took place at 7, 30, and 60 days. Micro-CT showed no statistical difference between the groups, but there was an increase in bone volume (56.26%), the number of trabeculae (2.76 mm), and intersection surface (26.76 mm2) and a decrease in total porosity (43.79%) in the PO+PG group, as well as higher values for the daily mineral apposition rate (7.16 µm/day). Histometric analysis presented material replacement and increased bone formation at 30 days compared to 7 days in both groups. Immunostaining showed a similar pattern between the groups, with an increase in proteins related to bone remodeling and formation. In conclusion, Plenum® Osshp + Plenum® Guide showed similar and sometimes superior results when compared to autogenous bone, making it a competent option as a bone substitute.

Abnormal amyloid precursor protein processing in periodontal tissue in a murine model of periodontitis induced by Porphyromonas gingivalis

OBJECTIVE

The study aimed to investigate the change of amyloid precursor protein (APP) processing and amyloid β (Aβ) metabolites in linking periodontitis to Alzheimer's disease (AD).

BACKGROUND

Aβ is one of the main pathological features of AD, and few studies have discussed changes in its expression in peripheral tissues or analyzed the relationship between the peripheral imbalance of Aβ production and clearance.

METHODS

A murine model of periodontitis was established by oral infection with Porphyromonas gingivalis (P. gingivalis). Micro-computed tomography (Micro-CT) was used to observe the destruction of the alveolar bone. Nested quantitative polymerase chain reaction (qPCR) was used to measure small quantities of P.gingivalis DNA in different tissues. Behavioral experiments were performed to measure cognitive function in the mice. The mRNA levels of TNF-α, IL-6, IL-8, RANKL, OPG, APP695, APP751, APP770, and BACE1 in the gingival tissues or cortex were detected by RT-PCR. The levels of Aβ1-40 and Aβ1-42 in gingival crevicular fluid (GCF) and plasma were tested by ELISA.

RESULTS

P. gingivalis oral infection was found to cause alveolar bone resorption and impaired learning and memory. P.gingivalis DNA was detected in the gingiva, blood and cortex of the P.gingivalis group by nested qPCR (p < .05). The mRNA expression of TNF-α, IL-6, IL-8, RANKL/OPG, and BACE1 in the gingival tissue was significantly higher than that in the control group (p < .05). Similarly, upregulated mRNA levels of APP695 and APP770 were observed in the gingival tissuses and cortex of the P. gingivalis group (p < .05). The levels of Aβ1-40 and Aβ1-42 in the GCF and plasma of the P. gingivalis group were significantly higher than those in the control group (p < .05).

CONCLUSION

P. gingivalis can directly invade the brain via hematogenous infection. The invasion of P. gingivalis could trigger an immune response and lead to an imbalance between Aβ production and clearance in peripheral tissues, which may trigger an abnormal Aβ metabolite in the brain, resulting in the occurrence and development of AD.

Effects of boric acid on alveolar sockets filling after dental extraction in rats

PURPOSE

After extraction, dental alveolus filling aims to reduce bone loss and maintain the alveolus volume during patient rehabilitation. Boric acid (BA) is a boron-derived compound with osteogenic properties and an interesting candidate for alveoli filling. This study aims to investigate the osteogenic capacity of the local application of BA in dental socket preservation.

METHODS

Thirty-two male Wistar rats were submitted to upper right incisor extraction and randomly divided into four groups (n = 8): control group (no intervention), BA (8 mg/kg) socket filling, bone graft (Cerabone®, Botiss, Germany), and BA + bone graft socket filling. Animals were euthanized 28 days after dental extraction. MicroCT and histological analysis were performed to evaluate the newly formed bone on the dental alveolus.

RESULTS

MicroCT analysis demonstrated that bone volume fraction (BV/TV), bone surface (BS), bone surface/bone volume ratio (BS/BV), bone surface density (BS/TV), trabecular thickness (Tb.Th), total bone porosity (Po-tot), and total volume of pore space (Po.V(tot)) from BA and BA + bone graft rats were significantly different from the control group. Histological evaluation displayed a delayed bone repair in BA rats, with the presence of connective tissue and inflammatory infiltrate. However, the BA + bone graft group demonstrated histological aspects like the bone graft animals, with less organized osteoblasts, suggesting inferior bone repair.

CONCLUSION

Osteogenic capacity did not depend on the BA local application after 28 days of dental extraction. The presence of inflammation in the BA group can represent toxicity induced by the substance dosage used.

Effects of different doses of ionizing radiation on alveolar bone repair in post-extraction tooth socket: an experimental study in rats

OBJECTIVE

This study aimed to evaluate the dose-response effects of ionizing radiation (IR) on alveolar bone repair and bone strength after tooth extraction.

MATERIALS AND METHODS

A total of 32 male Wistar rats were used in the study, 28 animals were included in the final analysis, and n = 7 for each experimental group. Mandibular first molars were extracted. After 7 days, the animals were randomly divided into four groups according to single-dose irradiation: NIr, control group; Ir15, irradiated at 15 Gy; Ir20, irradiated at 20 Gy; and Ir30, irradiated at 30 Gy. The tooth extraction sites were subjected to micro-computed tomography (micro-CT), histological, histomorphometric, and biomechanical analyses 14 days after extraction. Data were analyzed using one-way ANOVA followed by Tukey's post hoc test (α = 0.05).

RESULTS

Micro-CT analysis revealed that IR led to lower values of bone volume (BV, in mm3) (0.68 ± 0.08, P < 0.001) and bone volume fraction, ratio of the segmented bone volume to the total volume of the region of interest (BV/TV, in %) (44.1 ± 8.3, P < 0.001) for the Ir30 group compared to the control group. A significantly lower amount of newly formed bone was observed in the Ir30 (P = 0.005) than in the Ir15 group. The histomorphometric results of quantification of bone matrix neoformation and the micro-CT were in agreement, demonstrating greater damage to the Ir30 group. IR30 cells showed a lower percentage of densely packed collagen than control cells. No significant differences were found in the biomechanical parameters.

CONCLUSION

IR affects alveolar bone repair. A dose of 30 Gy reduced the bone healing process owing to a smaller amount of newly formed bone and a lower percentage of densely packed collagen. Therefore, a dose of 30 Gy can be used to successfully establish an animal model of an irradiated mandible that mimics the irradiated clinical conditions.

CLINICAL RELEVANCE

Radiotherapy can lead to severe side effects and tooth extraction is a major risk factor. A proper understanding of the pathological mechanisms of radiation in alveolar bone repair requires the establishment of a suitable animal model of clinical conditions.

Current Knowledge on the Healing of the Extraction Socket: A Narrative Review

The concept of extraction socket healing has been severally researched and reported over the years, since tooth extraction remains one of the most common procedures performed in the dental clinic. Understanding this healing process is of utmost importance because the outcome has a direct bearing on future prosthetic rehabilitation and, by extension, on patients' esthetics and masticatory function, among others. This mini review, therefore, summarized the current knowledge on the different stages of socket healing, including the biologic and clinical events that occur following tooth extraction up until the complete closure of the socket. Additionally, the modeling of the alveolar bone/process post extraction, and the resultant dimensional changes that, altogether, shape the bone, were reviewed and documented. The effects of various socket preservation interventions to mitigate these dimensional changes, and therefore preserve the alveolar process in a condition suitable for future prosthetic rehabilitation, were highlighted. Finally, a review of some of the factors that influence the entire process was also carried out.

Influence of age and gender on alveolar bone healing post tooth extraction in 129 Sv mice: a microtomographic, histological, and biochemical characterization

OBJECTIVES

To analyze the effect of biological sex and aging on craniofacial bone features in 129 Sv mice and their influence on dental socket healing post tooth extraction.

MATERIALS AND METHODS

A total of 52 129 Sv mice were used, of which 28 were young (3-4 months) and 24 were aged (17-18 months), equally distributed according to biological sex. After an upper right incisor extraction, mice specimens were collected at 7, 14, and 21-days post-surgery for microtomographic (microCT) and comprehensive histological analysis. Mandible, skull bones, and maxillae at 21 days were analyzed by microCT, while blood plasma samples were collected for the detection of key bone turnover markers (P1NP and CTX-1) by enzyme-linked immunosorbent (ELISA) assay.

RESULTS

Aged females depicted significantly decreased mineralized bone content in alveolar sockets in comparison to young females and aged males at day 7, and aged males at day 14. Mandible RCA and Ma.AR of aged females were also significantly decreased in comparison with young females. Histological evaluation revealed that all alveolar sockets healed at 21 days with inflammation resolution and deposition of new bone. Immunohistochemistry for TRAP revealed increased area density for osteoclasts in alveolar sockets of aged females when compared to young females at 21 days. While a significant increase in CTX-1 levels was detected in blood plasma of aged females when compared to young females, P1NP levels did not significantly change between young and older females. No significant changes were observed for males.

CONCLUSIONS

Age and gender can significantly affect craniofacial bones of 129 Sv mice, especially maxilla and mandible in females. Considering the altered bone resorption parameters and delayed alveolar bone healing in older females, careful deliberation is necessary during development of pre-clinical models for craniofacial research.

CLINICAL RELEVANCE

Aging can be a contributing factor to slower bone healing in craniofacial bones. However, there are no sufficient experimental studies that have addressed this phenomenon along with biological sex taken into consideration.

Alveolar Bone Preservation Using a Combination of Nanocrystalline Hydroxyapatite and Injectable Platelet-Rich Fibrin: A Study in Rats

Alveolar bone resorption is a post-extraction complication wherein there is a reduction in the dimensions and quality of the alveolar bone. This study aimed to examine the effects of implantation of a combination of nanocrystalline hydroxyapatite (nHA) and injectable platelet-rich fibrin (IPRF) on the expression of tartrate-resistant acid phosphatase (TRAP), alkaline phosphatase (ALP), osteocalcin (OCN), and new bone formation. A total of 32 male rats had their upper right incisors extracted under general anesthesia and were then divided into a control group, nHA group, IPRF group, and nHA-IPRF group. Decapitation was carried out on day 14 and day 28 in each group and the jaws of each rat were subjected to immunohistochemical and histological analysis. The results showed a decrease in TRAP expression in the nHA-IPRF group compared with the control group on day 14 (p = 0.074) and day 28 (p = 0.017). The study also showed an increase in ALP and OCN in the HA-IPRF group on day 14 and day 28 compared with the control group. New bone formation suggested a significant increase in the nHA-IPRF group compared with the control group on day 14 (p = 0.001) and day 28 (p = 0.001). nHA-IPRF implantation can suppress alveolar bone resorption, which is indicated by decreased TRAP expression, and it can increase bone growth, as indicated by increased expression of ALP, OCN, and new bone formation.

Alveolar ridge preservation: A review of concepts and controversies

The loss of thickness and height of the alveolar process after tooth extraction is a significant impediment to implant placement, which limits the aesthetic results of many restorative treatments. Alveolar ridge preservation can reduce bone resorption. Knowing how beneficial this procedure is can help clinicians decide if it is worth doing. The purpose of this article is to present a contemporary review of the different approaches to preserving the dimensions of the alveolar ridge. We analyze the alveolar healing process, atraumatic extraction techniques, graft materials, and controversies.

Antimicrobial and bone repair effects of boric acid in a rat model of dry socket (alveolar osteitis) following dental extraction

BACKGROUND

Alveolitis occurs after dental extraction without blood clot formation, leading to an inflammatory process and bacterial contamination. Boric acid (BA) demonstrates anti-inflammatory, antimicrobial, and osteogenic properties. This study aims to evaluate the possible antimicrobial effects and bone repair of BA in a rat model of alveolitis (dry socket).

METHODS

33 male Wistar rats were submitted to the extraction of the upper right incisor and dry socket induction. They were first divided into two groups: dry socket (n = 17) and dry socket + 0.75 % BA (n = 16). Samples for the microbiological analysis were collected immediately after dental extraction, at the detection of clinical alveolitis, 7, and 14 days after BA application. For microCT and histological analysis, samples from euthanized rats were used in 14 and 28 days after alveolitis detection.

RESULTS

Higher bacterial counts were found in 4-5 days after alveolitis induction, compared to the baseline in both experimental groups, decreasing significantly after 7 and 14 days of treatment with BA (P < 0.05). The microCT evaluation displayed increased bone volume, bone volume fraction, trabecular thickness, and bone mineral density in a time-dependent manner, regardless of BA treatment. On the other hand, the number of trabeculae and total bone porosity decreased over the 28 days of the experiment in the dry-socket group and both groups, respectively (P < 0.05). Histological analysis did not differ on bone repair in both experimental groups.

CONCLUSION

This was the first report investigating the effects of BA in a rat model of alveolitis regarding microbiological and bone repair aspects. The BA local application decreased the total aerobic and facultative bacteria counts and does not seem to benefit the bone repair after alveolitis development. This study paves the way for more studies involving alveolitis and different BA applications.

A natural polyphenol-functionalized chitosan/gelatin sponge for accelerating hemostasis and infected wound healing

Natural polymers have been particularly appealing for constructing hemostatic materials/devices, but it is still desirable to develop new natural polymer-based biomaterials with balanced hemostatic and wound-healing performance. In this work, a natural polyphenol-functionalized chitosan/gelatin sponge (PCGS) was prepared by the lyophilization of a chitosan/gelatin mixture solution (under a self-foaming condition to prepare the CGS) and subsequent chemical cross-linking with procyanidin (PC). Compared with the original CGS, PCGS exhibited an enhanced liquid-absorption ability, reduced surface charges, and similar/low hemolysis rate. Benefiting from such a liquid-absorption ability (∼4000% for whole blood and normal saline) and moderate surface charges, PCGS exhibited high in vitro hemostatic property and promising hemostatic performance in an in vivo femoral-artery-injury model. In addition, PCGS possessed higher antioxidant property and slightly decreased antibacterial ability than CGS, owing to the incorporation of PC. The feasibility of PCGS for treating infected wounds was further confirmed in an in vivo infected-tooth-extraction model, as the typical complication of intractable tooth-extraction bleeding. The present work demonstrated a facile approach for developing multifunctional hemostatic materials through the flexible management of natural polymers and polyphenols.

Definition of the Region of Interest for the Assessment of Alveolar Bone Repair Using Micro-computed Tomography

The objective of this study was to evaluate the influence of the extraction socket (distal or lingual root) and the type of region of interest (ROI) definition (manual or predefined) on the assessment of alveolar repair following tooth extraction using micro-computed tomography (micro-CT). The software package used for scanning, reconstruction, reorientation, and analysis of images (NRecon®, DataViewer®, CT-Analyzer®) was acquired through Bruker <  https://www.bruker.com  > . The sample comprised the micro-CT volumes of seven Wistar rat mandibles, in which the right first molar was extracted. The reconstructed images were analyzed using the extraction sockets, i.e., the distal and intermediate lingual root and the method of ROI definition: manual (MA), central round (CR), and peripheral round (PR). The bone volume fraction (BV/TV) values obtained were analyzed by two-way ANOVA with Tukey's post hoc test (α = 5%). The distal extraction socket resulted in significantly lower BV/TV values than the intermediate lingual socket for MA (P = 0.001), CR (P < 0.001), and PR (P < 0.001). Regarding the ROI, when evaluating the distal extraction socket, the BV/TV was significantly higher (P < 0.001) for MA than for CR and PR, with a lower BV/TV for CR. However, no significant difference was observed for MA (P = 0.855), CR (P = 0.769), or PR (P = 0.453) in the intermediate lingual extraction socket. The bone neoformation outcome (BV/TV) for alveolar bone repair after tooth extraction is significantly influenced by the ROI and the extraction socket. Using the predefined method with a standardized ROI in the central region of the distal extraction socket resulted in the assessment of bone volume, demonstrating the most critical region of the bone neoformation process.

Autogenous dentin combined with mesenchymal stromal cells as an alternative alveolar bone graft: an in vivo study

OBJECTIVE

Considering the chemical and structural properties of dentin, this study was aimed at evaluating the effect of dentin matrix alone or combined with mesenchymal stromal cells (MSC) on postextraction alveolar bone regeneration.

MATERIAL AND METHODS

Wistar rats were subjected to tooth extraction with osteotomy and allocated into groups according to the graft inserted: (1) Gelita-Spon^®, (2) Bio-Oss^®, (3) Dentin, (4) MSC, (5) Dentin/MSC, and (6) Control. Maxillae were analyzed by means of hematoxylin and eosin (H&E) staining, immunohistochemical (IHC) analysis, microcomputed tomography (micro-CT), and scanning electron microscopy (SEM). Serum levels of calcium and phosphorus were quantified.

RESULTS

The Bio-Oss group showed less bone than Gelita-Spon and Dentin/MSC; no other significant differences were seen in H&E analysis. The Bio-Oss group showed higher expression of collagen type I compared to the Dentin and Dentin/MSC groups and also higher osteocalcin expression than the Dentin/MSC group. There was a tendency of higher expression of osteopontin in the MSC, Dentin, and Dentin/MSC groups and higher VEGF in the MSC group. On micro-CT analysis, the Bio-Oss and the Dentin/MSC groups exhibited greater bone volume than the Control. Serum calcium and phosphorus levels did not significantly differ between the groups. SEM analysis depicted particles of Bio-Oss and dentin in the respective groups, as well as significant cellularity in the MSC group.

CONCLUSION

Autogenous nondemineralized dentin is an alternative for alveolar bone grafting, which can be improved by combination with MSC.

CLINICAL RELEVANCE

This work provides support for the clinical applicability of dentin graft alone or combined with MSC.

Application of Tissue Engineering in Manufacturing Absorbable Membranes to Improve the Osteopromoting Potential of Collagen

The membranes are an important biomaterial that contribute to osteopromotion. This study aimed to evaluate the osteopromotive potential of collagen membranes associated with Hydroxyapatite (HA) in critical size calvaria rat's defects. Ninety-six Albinus Wistar rats were divided into four groups: (CG) negative control: clot only (CG); positive control: porcine collagen membrane (BG); fish collagen membrane associated with HA (CP); bovine collagen membrane associated with HA (CB), analyzed at 7, 15, 30, and 60 postoperative days. At 30 days, membrane integrity was observed in the CB and fragments in the CP and BG groups were dispersed in the center of the defect. At 60 days, BG demonstrated better results with no statistical difference for the CP group (p = 0.199) and a statistically significant difference for the CB group (p = 0.013). The inflammatory profiles of the BG and CP groups were similar. Immunohistochemistry demonstrated at 60 days moderate osteopontin staining for the BG and CP groups, light staining for the CB, and intense osteocalcin staining for the BG, while the CB and CP groups demonstrated moderate staining. Microtomography revealed the highest mean bone volume (14.247 mm³) in the BG, followed by the CB (11.850 mm³), and CP (9.560 mm³) group. The collagen membranes associated with HA demonstrated an osteopromotive potential.

Bone Modeling after Orthodontic Extrusion: A Histomorphometric Pilot Study

During osteogenesis and bone modeling, high vascularity and osteoblastic/osteoclastic cell activity have been detected. A decrease in this activity is a sign of complete bone formation and maturation. Alveolar bone maturation seems to occur within weeks and months; however, the precise timing of the alveolar bone modeling is still unknown. The aim of this clinical pilot study was to investigate the bone modeling of neo-apposed tissue during orthodontic extrusive movements, through a histomorphometric analysis of human biopsies. This study was conducted on third mandibular molars sockets, and all teeth were extracted after orthodontic extrusion between 2010 and 2014. After different stabilization timings, extractions were performed, and a specimen of neo-deposed bone was harvested from each socket for the histomorphometric analysis. Histological parameters were evaluated to identify bone quantity and quality. This study included 12 teeth extracted from 9 patients. All specimens were composed of bone tissue. Bone samples taken after 1 and 1.5 months of stabilization presented remarkable percentages of woven bone, while after 2 months, a relevant decrease was observed. Histomorphometric analysis suggested that after orthodontic extrusion, a period of stabilization of 2 months allows the neo-deposed bone to mature.

The Role of Bone Grafts in Preventing Medication-Related Osteonecrosis of the Jaw: Histomorphometric, Immunohistochemical, and Clinical Evaluation in Animal Model

Objective

To evaluate the effects of inorganic bovine bone graft (Lumina Bone, Criteria, Brazil) and beta-tricalcium phosphate (β-TCP) graft (ChronOS, Synthes, Brazil) in rats with the risk of developing post-extraction medication-related osteonecrosis of the jaw (MRONJ).

Methods

Eighteen male Wistar rats weighing 350 to 450 g were induced to develop MRONJ using zoledronic acid for 5 weeks. In the sixth week, the right maxillary first molar was extracted. The animals in Group I (G1) did not receive bone grafts after tooth extraction, while Group II (G2) animals received inorganic bovine bone grafts, and Group III (G3) animals received beta-tricalcium phosphate (β-TCP) grafts. Clinical evaluation and histomorphometric and immunohistochemical analyses were performed. ANOVA and Tukey's statistical tests were used and a level of significance was considered to be 5%.

Results

In the clinical evaluation, animals from G2 and G3 did not present clinical manifestations of osteonecrosis, unlike the control group (G1) animals, which presented necrotic bone tissue exposure in all samples. In the histomorphometric evaluation, animals in G3 showed greater formation of bone tissue (66%) and less formation of bone lacuna (18%) than animals in G1 (58%/32%) and in G2 (59%/27%) (P < 0.05). Moderate (++) immunostaining was observed in G2 and G3 for RANKL, TRAP, and OC, while G1 showed moderate (++) labeling for OC and mild (+) immunostaining for TRAP and RANKL.

Conclusions

Greater formation of bone tissue and fewer bone lacunae were found in animals treated with β-TCP. In clinical evaluation, bone graft groups presented with the clinical manifestation of MRONJ and showed higher intensity of immunostaining for TRAP and RANKL. Despite the limitations of experimental animal studies, the results of this work may assist in the development of future clinical research for the prevention of MRONJ.

Characterizations of alveolar repair after mandibular second molar extraction: an experimental study in rats

BACKGROUND

Characterizations of rat mandibular second molar extraction socket with significantly different buccal and lingual alveolar ridge width remain unclear.

OBJECTIVE

To observe alterations in the alveolar ridge after extraction of mandibular second molars, and to examine processes of alveolar socket healing in an experimental model of alveolar ridge absorption and preservation.

METHODOLOGY

Eighteen Wistar rats were included and divided into six groups regarding healing time in the study. Bilateral mandibular second molars were extracted. The rats with tooth extraction sockets took 0, 1.5, 2, 3, 4 and 8 weeks of healing. Histological observation, tartrate-resistant acidic phosphatase (TRAP) staining, Masson's trichrome staining, immunohistochemical staining and micro-computed tomography (micro-CT) were applied to estimate alterations in the alveolar ridge.

RESULTS

Different buccal and lingual alveolar ridge width led to different height loss. Lingual wall height (LH) decreased significantly two weeks after tooth extraction. Buccal wall height rarely reduced its higher ridge width. From two to eight weeks after extraction, bone volume (BV/TV), density (BMD), and trabecular thickness (Tb.Th) progressively increased in the alveolar socket, which gradually decreased in Tb.Sp and Tb.N. LH showed no significant change during the same period. Osteogenic marker OCN and OPN increased during bone repair from two to eight weeks. The reduced height of the lingual wall of the tooth extraction socket was rarely repaired in the later repair stage. Osteoclast activity led to absorption of the alveolar ridge of the alveolar bone wall within two weeks after operation. We observed positive expression of EMMPRIN and MMP-9 in osteoclasts that participated in the absorption of the spire region.

CONCLUSION

Extraction of rat mandibular second molars may help the study of alveolar ridge absorption and preservation. The EMMPRIN-MMP-9 pathway may be a candidate for further study on attenuating bone resorption after tooth extraction.

Calvaria Critical Size Defects Regeneration Using Collagen Membranes to Assess the Osteopromotive Principle: An Animal Study

Guided bone regeneration (GBR) is a common practice in implantology, and it is necessary to use membranes in this process. The present study aimed to evaluate the osteopromotive principle of two porcine collagen membranes in critical-size defects at rats calvaria. Ninety-six Albinus Wistar rats were divided into BG (positive control), JS, CS, and CG (negative control) groups and were sacrificed at 7, 15, 30, and 60 days postoperatively. The samples were assessed by histological, histometric, immunohistochemical, and microtomographic analyses. More intense inflammatory profile was seen in the JS and CS groups (p < 0.05). At 60 days, the JS group showed a satisfactory osteopromotive behavior compared to BG (p = 0.193), while CS did not demonstrate the capacity to promote bone formation. At the immunohistochemical analysis, the CS showed mild labeling for osteocalcin (OC) and osteopontin (OP), the JS demonstrated mild to moderate for OC and OP and the BG demonstrated moderate to intense for OC and OP. The tridimensional analysis found the lowest average for the total volume of newly formed bone in the CS (84,901 mm2), compared to the BG (319,834 mm2) (p < 0.05). We conclude that the different thicknesses and treatment techniques of each membrane may interfere with its biological behavior.

Effects of inorganic mercury exposure in the alveolar bone of rats: an approach of qualitative and morphological aspects

BACKGROUND

In comparison to organic mercury (MeHg), the environmental inorganic mercury (IHg) can be found in some skin-lightening cosmestics were considered "harmless" for a long time. However, recent studies have shown that long-term exposure to low doses of IHg may affect biological systems. Therefore, this study investigated the effects of IHg long-term exposure to the alveolar bone of adult rats.

METHODS

Adult Wistar rats were distributed in control and HgCl₂ exposed (0.375 mg/kg/day). After 45 days, the rats were euthanized and both blood and hemimandibles were collected. Total blood Hg levels were measured and both inorganic and organic components of the alveolar bone were determined through XRD and ATR-FTIR. The microstructure of the alveolar bone was assessed by using micro-CT and the morphometric analysis was performed by using stereomicroscopy.

RESULTS

Alterations in the physicochemical components of the alveolar bone of exposed animals were observed. The bone changes represented a tissue reaction at the microstructural level, such as bone volume increase. However, no significant dimensional changes (bone height) were observed.

CONCLUSION

Exposure to IHg at this dose can promote microstructural changes and alteration in the organic and inorganic components in the alveolar bone.

Imaging Microstructural Damage and Alveolar Bone Loss in Rats Systemically Exposed to Methylmercury: First Experimental Evidence

The alveolar bone is an important mineralized structure of the periodontal support apparatus, and information about the methylmercury (MeHg) effects on the structural integrity is scarce. Therefore, this study aimed to investigate whether systemic, chronic, and low-dose exposure to MeHg can change the alveolar bone microstructure of rats. Adult Wistar rats (n = 30) were exposed to 0.04 mg/kg/day of MeHg or vehicle through intragastric gavage. The animals were euthanized after 60 days, and blood samples were collected for trolox equivalent antioxidant capacity (TEAC), glutathione (GSH), lipid peroxidation (LPO), and comet assays. The mandible of each animal was collected and separated into hemimandibles that were used to determine the total Hg level in the bone and to analyze microstructural damage and alveolar bone loss in terms of trabecular number (Tb.N), trabecular thickness (Tb.Th), bone volume fraction (BV/TV), and exposed root area of the second molars. MeHg exposure triggered oxidative stress in blood represented by lower levels of GSH and TEAC and the increase in LPO and DNA damage of the blood cells. High total Hg levels were found in the alveolar bone, and the microstructural analyses showed a reduction in Tb.N, Tb.Th, and BV/TV, which resulted in an increase in the exposed root area and a decrease in bone height. Long-term MeHg exposure promotes a systemic redox imbalance associated with microstructural changes and alveolar bone loss and may indicate a potential risk indicator for periodontal diseases.

Effect of Curcumin on Alterations of Alveolar Bone Remodeling and Expression of Receptor Activator of Nuclear Factor-κ B Ligand in Rat Tooth During Tooth Movement

Objective: To evaluate the effect of Curcumin on Alterations of Alveolar Bone Remodeling and Expression of RANKL in Rat Tooth during Tooth Movement. Methods: 64 SD rats were randomly divided into 4 groups, Model, Adrb2, Cur and Cur + Pro groups. The rat orthodontic teeth movement models were established.The rats were injected corresponding reagents according to weight and were sacrificed on day 0, 7, 14 and 21. The movement distance of first molar of rats was measured by Vernier caliper.The numbers of osteoclasts were observed through TRAP staining. The change of micro-structure of alveolar bone was evaluated by Micro-CT. Results: The trends of the distance of teeth movement and numbers of osteoclast were the same: Cur group β Adrb2 group > Model groups Cur+Pro group (P < 0.05). Micro-CT scan showed that curcumin could reduce the bone volume fraction (BV/TV), bone trabecular density (MTPD), and increase the trabecular resolution (TB. SP). When propranolol was given at the same time, the effect of curcumin disappeared. Conclusion: Curcumin could promote the resorption of alveolar bone at the pressure side and increase the osteoclast numbers so that the alveolar bone became looser which was beneficial to the movement of orthodontic tooth.

Surface activation with oxygen plasma promotes osteogenesis with enhanced extracellular matrix formation in three-dimensional microporous scaffolds

Various types of synthetic polyesters have been developed as biomaterials for tissue engineering. These materials commonly possess biodegradability, biocompatibility, and formability, which are preferable properties for bone regeneration. The major challenge of using synthetic polyesters is the result of low cell affinity due to their hydrophobic nature, which hinders efficient cell seeding and active cell dynamics. To improve wettability, plasma treatment is widely used in industry. Here, we performed surface activation with oxygen plasma to hydrophobic copolymers, poly(l-lactide-co-trimethylene carbonate), which were shaped in 2D films and 3D microporous scaffolds, and then we evaluated the resulting surface properties and the cellular responses of rat bone marrow stem cells (rBMSC) to the material. Using scanning electron microscopy and Fourier-transform infrared spectroscopy, we demonstrated that short-term plasma treatment increased nanotopographical surface roughness and wettability with minimal change in surface chemistry. On treated surfaces, initial cell adhesion and elongation were significantly promoted, and seeding efficiency was improved. In an osteoinductive environment, rBMSC on plasma-treated scaffolds exhibited accelerated osteogenic differentiation with osteogenic markers including RUNX2, osterix, bone sialoprotein, and osteocalcin upregulated, and a greater amount of collagen matrix and mineral deposition were found. This study shows the utility of plasma surface activation for polymeric scaffolds in bone tissue engineering.

Bone Regeneration Assessment of Polycaprolactone Membrane on Critical-Size Defects in Rat Calvaria

Biomaterials for use in guided bone regeneration (GBR) are constantly being investigated and developed to improve clinical outcomes. The present study aimed to comparatively evaluate the biological performance of different membranes during the bone healing process of 8 mm critical defects in rat calvaria in order to assess their influence on the quality of the newly formed bone. Seventy-two adult male rats were divided into three experimental groups (n = 24) based on the membranes used: the CG—membrane-free control group (only blood clot, negative control), BG—porcine collagen membrane group (Bio-Guide^®, positive control), and the PCL—polycaprolactone (enriched with 5% hydroxyapatite) membrane group (experimental group). Histological and histometric analyses were performed at 7, 15, 30, and 60 days postoperatively. The quantitative data were analyzed by two-way ANOVA and Tukey’s test (p < 0.05). At 7 and 15 days, the inflammatory responses in the BG and PCL groups were significantly different (p < 0.05). The PCL group, at 15 days, showed a large area of newly formed bone. At 30 and 60 days postoperatively, the PCL and BG groups exhibited similar bone healing, including some specimens showing complete closure of the critical defect (p = 0.799). Thus, the PCL membrane was biocompatible, and has the potential to help with GBR procedures.

Effects of osteoporosis on alveolar bone repair after tooth extraction: A systematic review of preclinical studies

OBJECTIVE

This systematic review aimed to address whether the alveolar socket repair after a tooth extraction is impacted by an osteoporotic phenotype and propose methodological observations.

DESIGN

A search strategy in MEDLINE/PubMed, EMBASE, Web of Science, and Scopus databases was performed. Quality assessment was carried out through the SYRCLE Risk of Bias tool.

RESULTS

Out of the 1147 potentially relevant records, 25 met the inclusion criteria. Most of the studies were performed in rats, and ovariectomy (OVX) was the most frequent osteoporosis induction method. Histomorphometry, micro-computed tomography (microCT), and immunohistochemistry were the main bone repair evaluation methods. Most of the included studies (88 %) presented negative impacts of osteoporosis on the alveolar socket repair. Only three studies (12 %) showed no statistical differences among groups. Overall, most of the quality assessment categories presented a high percentage of unclear risk of bias due to insufficient information in the studies.

CONCLUSIONS

The results indicated that an osteoporotic phenotype seems to impair alveolar socket repair after tooth extraction. However, there is still a lack of information and standardization. Therefore, further studies should consider the proposed methodological aspects regarding animal characteristics, OVX associated with a low calcium diet, waiting 8 weeks to osteoporosis induction, maxillary molars as the best option for tooth extraction, confirming and reporting OVX and osteoporosis success, and an appropriate method of repair analysis.

Bone repair assessment of critical size defects in rats treated with mineralized bovine bone (Bio-Oss®) and photobiomodulation therapy: a histomorphometric and immunohistochemical study

This study aimed to investigate the effects of administering photobiomodulation therapy (PBM) with bovine bone matrix on critical size defects in rats. Seventy-two adult male rats (albinus, Wistar), 90 days old, were used. Defect of 5 mm in diameter was made in their calvaria. The animals were divided into 4 groups: C-blood clot, B-Bio-Oss®, L-PBM, B+L-Bio-Oss®+PBM. Each group has been subdivided into 07, 30, and 60 days of observation. For PBM, a low GaAlAs energy of 660 nm was irradiated, total energy density of 45 J/cm² . PBM was conducted in a trans-surgical form once only. For immunohistochemistry, a semi-quantitative analysis was made of expression of osteoprotegerin (OPG), nuclear kappa B-factor ligand receptor activator (RANKL), and tartrate-resistant acid phosphatase (TRAP). All histomorphometric data were statistically analyzed by ANOVA and Tukey test, significance level of 5%. The groups that showed the highest proportion of neoformation were L (0.39% ± 0.13) and C (0.37% ± 0.97), but groups B and B+L had larger defect size (C-1.75 mm² ± 0.40, B-3.02 mm² ± 0.63, L-2.45 mm² ± 0.53, B+L-3.23 mm² ± 1.01). In immunohistochemistry, groups B and B+L had higher immunostaining scores for OPG and RANKL at 60 days, and TRAP immunostaining increased in all groups at 30 days, but group L was the only one to present specimens with score 0. Although, at 60 days, groups L and C presented the highest proportion of bone neoformation, at 30 days group B+L had more than twice as much bone neoformation as group B, the choice of treatment application should depend on the aim of the treatment.

In Vivo Comparative Evaluation of Biocompatibility and Biodegradation of Bovine and Porcine Collagen Membranes

Mechanical barriers prevent the invasion of the surrounding soft tissues within the bone defects. This concept is known as Guided Bone Regeneration (GBR). The knowledge about the local tissue reaction and the time of degradation of absorbable membranes favors the correct clinical indication. This study aimed to evaluate the biocompatibility and biodegradation of a bovine collagen membrane (Lyostypt^®, São Gonçalo, Brazil) and compare it to a porcine collagen membrane (Bio-Gide^®) implanted in the subcutaneous tissue of mice, following ISO 10993-6:2016. Thirty Balb-C mice were randomly divided into three experimental groups, LT (Lyostypt^®), BG (Bio-Gide^®), and Sham (without implantation), and subdivided according to the experimental periods (7, 21, and 63 days). The BG was considered non-irritant at seven days and slight and moderate irritant at 21 and 63 days, respectively. The LT presented a small irritant reaction at seven days, a mild reaction after 21, and a reduction in the inflammatory response at 63 days. The biodegradation of the LT occurred more rapidly compared to the BG after 63 days. This study concluded that both membranes were considered biocompatible since their tissue reactions were compatible with the physiological inflammatory process; however, the Bio-Gide^® was less degraded during the experimental periods, favoring the guided bone regeneration process.

Miniplates coated by plasma electrolytic oxidation improve bone healing of simulated femoral fractures on low bone mineral density rats

The treatment of polytrauma patients represents a great challenge in the maxillofacial and orthopedic surgery fields. Therefore, this study tested the hypothesis that the use of a bioactive coating (by plasma electrolytic oxidation, PEO) on titanium microplates could improve the fracture healing of low bone mineral density (BMD) rats. Thirty female rats underwent bilateral ovariectomy surgery (OVX), and 35 rats underwent fake surgery (SHAM). Three months later, animals were subjected to femoral fracture simulation and were fixed with either non-coated (CONV) or coated (PEO) titanium miniplates. Eight weeks postoperatively, microplate/bone complexes were analyzed through computed microtomography, histometric, confocal microscopy, molecular, and biomechanical analysis. Bioactive elements (Ca and P) were incorporated on the PEO microplate and the surface was modified in a volcano-like structure. In the microCT analysis the OVX/PEO group had greater values for Tb.Th (bone trabecular thickness), Tb.Sp (separation of bone trabeculae) and Tb.N (number of trabeculae) parameters compared to the OVX/CONV group. According to histometric analysis, the OVX/PEO group showed significantly higher new bone formation than the OVX/CONV group (P < 0.05). For the fluorochrome area, the OVX groups (PEO and CONV) showed greater values for calcein precipitation (old bone) than alizarin red (new bone). Molecular results showed greater values for proteins related to the final phase of bone formation (P < 0.05) in the OVX/PEO group. The OVX/PEO group showed higher bone/miniplate system resilience compared to the others (P < 0.05). It was concluded that PEO coating optimizes bone healing on simulated femoral fractures in low bone mineral density rats. This sheds new light in the treatment of osteoporotic patients with bone fractures.

IN VIVO EVALUATION OF BOVINE XENOGRAFT ASSOCIATED WITH OXYGEN THERAPY IN ALVEOLAR BONE REPAIR

In order to preserve alveolar bone thickness and width after extraction, clinical strategies have been adopted to reduce or eliminate the need for future surgical interventions to increase the alveolar ridge. The use of xenogeneic biomaterials has been increasing for such application. The association of bone substitutes with active oxygen-based materials, which is essential in the wound healing process, could accelerate the bone repair, optimizing the maintenance of alveolar architecture after extraction. However, the truth of this hypothesis is not clear. The present study aimed to compare the biological response to inorganic bovine bone graft Bonefill® (BF), associated or not with active oxygen-based gel Oral gel Blue ® m (BF+BM), in alveolar bone repair. Twenty female Wistar rats were randomly distributed, the left upper central incisor was extracted and the dental sockets were filled with BF in the control group (n=10), and with BF+BM in the experimental group (n=10). After 7- and 42-days' post implantation (n=5), the animals were euthanized, and the samples were processed for descriptive histological and histomorphometric evaluations. The results showed no significant difference between the groups (p>0.05). Both groups presented a time-dependent increase of new formed bone and biosorption biomaterial (p=0.0001). While the biomaterial analyzed was considered compatible and osteoconductive, the association with Blue ® m gel did not improve or interfere with the bone repair after the experimental periods.

The preventive effect of medicinal herbal extract and gelatin sponge on alveolar osteitis: An in vivo micro-computed tomography and immunohistochemical analysis in rats

OBJECTIVE

The purpose of this study was to evaluate the preventive effect of medicinal herbal extract (MHE) and gelatin sponge on alveolar osteitis (AO) in an experimental rat model.

DESIGN

Twenty-one Sprague-Dawley male rats with a mean age of 12 weeks were used. After extraction of the maxillary right first molar, an AO model was created for each animal. The animals were randomly separated to three equal groups. Group I served as a control, Group II was subjected to an intra-alveolar MHE application, and gelatin sponge was left in the sockets of Group III. On the 7th post-extraction day, the animals were sacrificed. The specimens were analyzed by micro-computed tomography (micro-CT), histopathologically and immunohistochemically.

RESULTS

Macroscopic evaluation revealed mild to intense signs of AO in all groups, but the difference was not significant (p < 0.05). Micro-CT analysis showed that bone formation was the highest in Group III (bone volume/total volume; 10.63 ± 4.9 %), whereas bone mineral density was the highest in Group I (2.05 ± 0.2 g/cm³). The difference was not significant (p > 0.05). In Group III, only 16.7 % of specimens showed no signal of inflammatory response (p < 0.01). The difference was not significant between the positive labeling for receptor activator of nuclear kappa-β (RANK), receptor activator of nuclear kappa-β ligand (RANKL), osteoprotegerin and osteopontin, but the intensity of Groups II and III was higher than the Group I for osteopontin (p < 0.01).

CONCLUSIONS

MHE and gelatin sponge were not effective enough to prevent alveolar osteitis, but positive results were obtained in bone healing.

Delayed alveolar bone repair and osteonecrosis associated with Zoledronic Acid therapy in rats: macroscopic, microscopic and molecular analysis

Objective

This study aims to evaluate bone repair and the development of the medication related osteonecrosis of the jaw (MRONJ) associated with the use of zoledronic acid in Wistar rats.

Methodology

48 male Wistar rats were divided into four groups: ZA, treated with intraperitoneal zoledronic acid, 0.6 mg/kg every 28 days, totaling five doses; control (C), treated with 0.9% sodium chloride; ZA-surgical (SZA) and C-surgical (SC), submitted to extraction of the right upper molars 45 days after the first application. Alveolar bone repair was evaluated by macroscopic and histological analysis. Protein expression evaluations were performed by qPCR.

Results

Macroscopic evaluation showed that 91.66% (11) of the animals in the SZA group and 41.66% (5) from the SC group presented solution of epithelium continuity (P<0.05). All animals in the SZA group and none in the SC group had bone sequestration. The area of osteonecrosis was higher in the SZA group than in the SC group (P<0.05). In molecular evaluation, the SZA group presented changes in the expression of markers for osteoclasts, with increased RANK and RANKL, and a decrease in OPG.

Conclusion

The results highlighted strong and evident interference of zoledronic acid in bone repair of the socket, causing osteonecrosis and delayed bone remodeling.

Assessment of irradiated socket healing in the rabbit's mandible: Experimental study

As bone healing is altered after external radiation therapy, its evaluation is mandatory and lacks in clinical practice. The aim of the pilot study was to validate micro computed tomography (microCT) as a simple and reliable technique for assessing irradiated bone healing in the rabbit's mandible and compare with histologic findings. Nineteen rabbits (female New Zealand white) were used. The radiation protocol consisted of 5 sessions delivering 8.5 Gy each. MicroCT was performed at D0, D7, D14, D28 and D42 for the control group and D0, D28 and D42 for the irradiated group. A modified Perry's score was determined on histologic samples, and comparison between microCT and histological findings was performed. The main differences between irradiated and non-irradiated rabbits were observed at Day 28 and 42. There was a strong correlation between imaging and histologic findings. Radiation decreases bone quality and bone mineral density. As the correlation was strong between microCT and histologic findings, micro imaging could be considered as a simple and reliable technique to assess bone healing after radiation therapy and allows an easy comparison between samples, without invasive procedures. Great attention should be kept on the parameters and on the region of interest. The development of in-vivo microCT enlarges the perspectives of microCT use in experimental studies, avoiding invasive procedures, and preserving animal lives and well-being, and furthermore lead to clinical applications.

Is the Bacterial Cellulose Membrane Feasible for Osteopromotive Property?

Guided bone regeneration was studied to establish protocols and develop new biomaterials that revealed satisfactory results. The present study aimed to comparatively evaluate the efficiency of the bacterial cellulose membrane (Nanoskin^®) and collagen membrane Bio-Gide^® in the bone repair of 8-mm critical size defects in rat calvaria. Seventy-two adult male rats were divided into three experimental groups (n = 24): the CG—membrane-free control group (only blood clot, negative control), BG—porcine collagen membrane group (Bio-Guide^®, positive control), and BC—bacterial cellulose membrane group (experimental group). The comparison periods were 7, 15, 30, and 60 days postoperatively. Histological, histometric, and immunohistochemical analyses were performed. The quantitative data were subjected to 2-way ANOVA and Tukey’s post-test, and p < 0.05 was considered significant. At 30 and 60 days postoperatively, the BG group showed more healing of the surgical wound than the other groups, with a high amount of newly formed bone (p < 0.001), while the BC group showed mature connective tissue filling the defect. The inflammatory cell count at postoperative days 7 and 15 was higher in the BC group than in the BG group (Tukey’s test, p = 0.006). At postoperative days 30 and 60, the area of new bone formed was greater in the BG group than in the other groups (p < 0.001). Immunohistochemical analysis showed moderate and intense immunolabeling of osteocalcin and osteopontin at postoperative day 60 in the BG and BC groups. Thus, despite the promising application of the BC membrane in soft-tissue repair, it did not induce bone repair in rat calvaria.

Ethanol binge drinking exposure affects alveolar bone quality and aggravates bone loss in experimentally-induced periodontitis

Background

Periodontitis is a multifactorial inflammatory disease of tooth supporting tissues caused by oral biofilms, influenced by environmental and genetic factors, among others. Ethanol consumption has been considered a factor that enhances alveolar bone loss, especially in high doses. The present study aims to investigate the changes promoted by ethanol binge drinking per se or associated with ligature-induced periodontal breakdown on alveolar bone loss.

Materials and methods

Thirty-two Wistar rats were randomly allocated into four groups: control (C), ethanol (3g/kg/day; 3 days On-4 days Off protocol by gavage for 28 days, EtOH), experimental periodontitis (EP) and experimental periodontitis plus ethanol administration (EP+EtOH). On day 14^th, periodontitis was induced by ligatures that were placed around the lower first molars. On day 28^th, the animals were euthanized and mandibles were submitted to stereomicroscopy for exposed root area analysis and micro-computed tomography (micro-CT) for the evaluation of alveolar bone loss and microstructural parameters.

Results

The results revealed that ligature-induced alveolar bone loss is aggravated by ethanol binge drinking compared to controls (1.06 ± 0.10 vs 0.77 ± 0.04; p<0.0001). In addition, binge drinking per se altered the alveolar bone quality and density demonstrating a reduction in trabecular thickness, trabecular number parameter and bone density percentual. Periodontal disorder plus ethanol binge drinking group also demonstrated reduction of the quality of bone measured by trabecular thickness.

Conclusions

In conclusion, intense and episodic ethanol intake decreased alveolar bone quality in all microstructural parameters analyzed which may be considered a modifying factor of periodontitis, intensifying the already installed disease.

β-catenin and Its Relation to Alveolar Bone Mechanical Deformation - A Study Conducted in Rats With Tooth Extraction

The aim of this study was to analyze the relationship between alveolar bone deformation and β-catenin expression levels in response to the mechanical load changed by dental extraction in adult rats. Twenty-four male rats (Rattus norvegicus albinus), Wistar linage, at 2 months of age, were used. The right upper incisor tooth was extracted, and euthanasia occurred in periods 5 (n = 6), 7 (n = 6), and 14 (n = 6) days after Day 0. In the control group (n = 6), the dentition was maintained. The euthanasia occurred within 14 days after day 0. After euthanasia, the rats of all groups had their left jaw with tooth removed and separated in the middle. The pieces were undergone routine histological processing and then the immunohistochemical marking were performed to label expression of the primary β-catenin antibody, which was evaluated by qualitative and quantitative analysis. One head by each group (control and experimental) was submitted to computerized microtomography. After the three-dimensional reconstruction of the skull of the rat in each group, the computational simulation for finite elements analysis were performed to simulate a bite in the incisors. In finite element analysis, the strain patterns were evaluated after the application of bite force. The results were analyzed considering the areas in which changes in the amount of deformations were detected. The action of the bite force in the experimental condition, resulted in a uniform distribution of the amount of deformations, in addition to lower amount of deformation areas, differentiating from the control group. Comparing with the control group, the levels of β-catenin signaled in the lingual bone of the middle third of the alveolar bone were raised in the periods of 5 and 14 days. The increased β-catenin positive staining intensity was concentrated on osteocytes and gaps of osteocytes. The findings of the present study were in accordance with our hypothesis that the condition of dental extraction can cause the expression of β-catenin and alter the regimes of bone deformation.

Evaluation of immediate cell viability and repair of osteotomies for implants using drills and piezosurgery. A randomized, prospective, and controlled rabbit study

PURPOSE

The objective of this study was to evaluate the immediate bone damage and bone repair after osteotomy for implants using conventional drills and drills powered by piezoelectric motor.

MATERIALS AND METHODS

Twelve rabbits received a tibial osteotomy with a conventional drill (control), with a diamond like carbon drill (DLC) and with a piezoelectric drill (Piezo). The animals were euthanized immediately, 30 and 60 days postoperatively. The tibias were removed and analyzed by means of histomorphometry, immunohistochemistry and microtomography.

RESULTS

The immediate damage to the tissue at the cavity margins was similar (P > .05). At 30 and 60 days, the amount of newly formed bone tissue was similar (P > .05). Osteocalcin was intense score at 60 days in Piezo group. Microtomography revealed that bone volume at 30 days (control 3.8; DLC 4.3; and Piezo 2.4) and 60 days (control 4.9; DLC 4.82; and Piezo 3.95) were similar. There was a significant difference in bone formation between 30 (2.4) and 60 days (3.95) for the Piezo group (P = .016).

CONCLUSION

The immediate effects and repair of cavities made using conventional, DLC coated, or ultrasound drills were similar.

Systemic administration of curcumin or piperine enhances the periodontal repair: a preliminary study in rats

OBJECTIVES

Studies have documented the anti-inflammatory effects of spices, which may be related to treatment of chronic diseases. The purpose of this study was to evaluate the influence of curcumin and piperine and their association on experimental periodontal repair in rats.

MATERIALS AND METHODS

Periodontitis was induced via the installation of a ligature around the first molar. After 15 days, the ligatures were removed, and the rats were separated into groups (12 animals per group): (i) curcumin, (ii) piperine, (iii) curcumin+piperine, (iv) corn oil vehicle, and (v) control group (animals had ligature-induced periodontitis but were not treated). The compounds were administered daily, for 15 days by oral gavage. Animals were euthanized at 5 and 15 days, and hemimaxillae and gingival tissues were harvested. Bone repair was assessed by μCT (microcomputer tomography). Histological sections were stained with hematoxylin/eosin (H/E) for the assessment of cellular infiltrate or picrosirius red for quantification of collagen content, and subjected to immunohistochemistry for detecting NF-ĸB. Gingival tissues were used to evaluate levels of TGF-β and IL-10 (ELISA).

RESULTS

Curcumin and piperine increased the TGF-β level, significantly improved the collagen repair, and decreased the cellularity and activation of NF-ĸB in the periodontal tissues, but only curcumin caused a significant increase in early bone repair.

CONCLUSION

Curcumin and piperine promoted a substantive effect on tissue repair; however, there was not synergistic effect of compounds administered in combination.

CLINICAL RELEVANCE

Curcumin and piperine stimulates the tissue repair and may be potential candidates for the treatment of periodontal disease.