Efficacy of a single Nd:YAG laser dose in reducing pain after mandibular third molar extraction: a prospective randomized controlled clinical trial.

The purpose is to explore the analgesic effect of a single Nd:YAG laser dose after mandibular third molar extraction. This was a prospective randomized controlled clinical trial. Subjects were enrolled according to the inclusion and exclusion criteria and randomly divided into the experimental and control groups. In the experimental group, the wound was irradiated with the Nd:YAG laser (wavelength, 1064 nm; output power, 1.5 W; energy density, 45 J/cm2; and power density, 1.5/cm2, pulsed mode) immediately after mandibular third molar extraction for 120 s (30 s at each site). In the control group, the laser working tip was placed near the extraction site but not activated. The primary outcome was the visual analog scale (VAS) pain scores in both groups at 2, 4, 12, 24, 48, and 72 h and 7 days after surgery. Secondary outcomes included wound healing scores and adverse reactions. The VAS score was significantly lower in the experimental group than in the control group at 2 and 4 h after surgery, while there was no significant difference in the VAS score between the two groups at 12, 24, or 48 h or 7 days after surgery. There were no significant differences in the wound healing scores between the two groups on postoperative day 7. No adverse reactions were observed in any of the laser-irradiated areas. A single Nd:YAG laser dose was effective in reducing pain at 2 and 4 h after mandibular third molar extraction. China Clinical Trial Registry: ChiCTR2000033870 (Registration Date: 2020-6-15).

Exosomes Derived from Adipose Tissue-Derived Mesenchymal Stromal Cells Prevent Medication-Related Osteonecrosis of the Jaw through IL-1RA.

Medication-related osteonecrosis of the jaw (MRONJ) is a severe disease with unclear pathogenesis. Adipose tissue-derived mesenchymal stromal cells (MSC(AT)s) serve as a special source for cell therapy. Herein, we explored whether exosomes (Exo) derived from MSC(AT)s promote primary gingival wound healing and prevent MRONJ. An MRONJ mice model was constructed using zoledronate (Zol) administration and tooth extraction. Exosomes were collected from the conditioned medium (CM) of MSC(AT)s (MSC(AT)s-Exo) and locally administered into the tooth sockets. Interleukin-1 receptor antagonist (IL-1RA)-siRNA was used to knock down the expression of IL-1RA in MSC(AT)s-Exo. Clinical observations, micro-computed tomography (microCT), and histological analysis were used to evaluate the therapeutic effects in vivo. In addition, the effect of exosomes on the biological behavior of human gingival fibroblasts (HGFs) was evaluated in vitro. MSC(AT)s-Exo accelerated primary gingival wound healing and bone regeneration in tooth sockets and prevented MRONJ. Moreover, MSC(AT)s-Exo increased IL-1RA expression and decreased interleukin-1 beta (IL-1ß) and tumor necrosis factor-α (TNF-α) expression in the gingival tissue. The sequent rescue assay showed that the effects of preventing MRONJ in vivo and improving the migration and collagen synthesis abilities of zoledronate-affected HGFs in vitro were partially impaired in the IL-1RA-deficient exosome group. Our results indicated that MSC(AT)s-Exo might prevent the onset of MRONJ via an IL-1RA-mediated anti-inflammatory effect in the gingiva wound and improve the migration and collagen synthesis abilities of HGFs.

Histological analysis for pulp mineralisation after severe intrusive luxation of immature molars in rats.

BACKGROUND/AIM: Pulp mineralisation is a survival process that may occur in the pulp of immature teeth following trauma. However, the mechanism of this process remains unclear. The aim of this study was to evaluate the histological manifestations of pulp mineralisation after intrusion in immature molars of rats. MATERIALS AND METHODS: Three-week-old male Sprague-Dawley rats were subjected to intrusive luxation of the right maxillary second molar by an impact force from a striking instrument through a metal force transfer rod. The left maxillary second molar of each rat was used as a control. The control and injured maxillae were collected at 3, 7, 10, 14, and 30 days after trauma (n = 15 per time group) and evaluated using haematoxylin and eosin staining and immunohistochemistry. Independent two-tailed Student's t-test was used for statistical comparison of the immunoreactive area. RESULTS: Pulp atrophy and mineralisation were observed in 30%-40% of the animals, and no pulp necrosis occurred. Ten days after trauma, pulp mineralisation, with osteoid tissue rather than reparative dentin, formed around the newly vascularised areas in the coronal pulp. CD90-immunoreactive cells were observed in the sub-odontoblastic multicellular layer in control molars, whereas the number of these cells was decreased in the traumatised teeth. CD105 localised in cells around the pulp osteoid tissue of the traumatised teeth, whereas in control teeth, it was only expressed in the vascular endothelial cells of capillaries in the odontoblastic or sub-odontoblastic layers. In specimens with pulp atrophy at 3-10 days after trauma, hypoxia inducible factor expression and CD11b-immunoreactive inflammatory cells increased. CONCLUSIONS: Following intrusive luxation of immature teeth without crown fractures in rats, no pulp necrosis occurred. Instead, pulp atrophy and osteogenesis around neovascularisation with activated CD105-immunoreactive cells were observed in the coronal pulp microenvironment characterised by hypoxia and inflammation.

Low-level laser therapy prevents medication-related osteonecrosis of the jaw-like lesions via IL-1RA-mediated primary gingival wound healing.

BACKGROUND: Medication-related osteonecrosis of the jaw (MRONJ) is a serious debilitating disease caused by anti-resorption and anti-angiogenesis drugs, significantly affecting patients' quality of life. Recent studies suggested that primary gingival wound healing may effectively prevent the development of MRONJ. This study aimed to evaluate the effects of low-level light therapy (LLLT) on promoting gingival wound healing in extraction sockets of MRONJ-like mice and preventing the occurrence of MRONJ. Furthermore, we explored underlying mechanisms. METHODS: Mice were randomly divided into the Ctrl, Zol, and Zol + LLLT groups. Administration of zoledronate and tooth extraction of bilateral maxillary second molars were used to build the MRONJ model, and LLLT was locally administered into the tooth sockets to examine the effect of LLLT. Next, to explore the function of IL-1RA, we performed LLLT with interleukin-1 receptor antagonist (IL-1RA) neutralizing antibody (named Zol + LLLT + IL-1RA NAb group) or negative control antibodies for tooth extraction in subsequent rescue animal experiments. Stereoscope observations, micro-computed tomography, and histological examination were conducted to evaluate gingival wound healing and bone regeneration in tooth sockets. The effects of LLLT on the migration capacities of zoledronate-treated epithelial cells were assessed in vitro. RESULTS: LLLT promoted primary gingival wound healing without exposed necrotic bone. Micro-computed tomography results showed higher bone volume and mineral density of the tooth sockets after LLLT. Histology analysis showed complete gingival coverage, obvious bone regeneration, and reduced soft tissue inflammation, with down-regulated pro-inflammation cytokines, like interleukin-1 beta (IL-1ß) and tumor necrosis factor-α (TNF-α), and up-regulated IL-1RA expression in the gingival tissue in the LLLT group. The rescue assay further showed that the effects of LLLT promoting gingival wound healing and preventing MRONJ might be partially abolished by IL-1RA neutralizing antibodies. In vitro studies demonstrated that LLLT accelerated zoledronate-treated epithelial cell migration. CONCLUSIONS: LLLT might promote primary gingival wound healing and contribute to subsequent bone regeneration of the tooth extractions in MRONJ-like lesions via IL-1RA-mediated pro-inflammation signaling suppression.

Exosomes from Adipose-Derived Stem Cells Can Prevent Medication-Related Osteonecrosis of the Jaw.

The treatment measures of medication-related osteonecrosis of the jaw (MRONJ) is a worldwide challenge in oral and maxillofacial surgery because of its unclear pathogenesis. Previous studies suggested that mesenchymal stem cells played important roles in promoting MRONJ lesion healing, but the detailed mechanisms were unknown. Increasing numbers of studies have demonstrated that exosomes derived from mesenchymal stem cells, especially adipose-derived stem cells, have key roles in stem cell-based therapies by accelerating bone remodeling, facilitating angiogenesis, and promoting wound healing. We hypothesized that exosomes derived from adipose-derived stem cells can prevent MRONJ by accelerating gingival healing and enhancing bone remodeling processes. Our results may provide a promising therapeutic option for MRONJ clinical therapy.

Increased apoptosis of gingival epithelium is associated with impaired autophagic flux in medication-related osteonecrosis of the jaw.

Macroautophagy/autophagy has both negative and positive aspects in the development of many diseases. Yet, its exact role and specific mechanism in the onset of medication-related osteonecrosis of the jaw (MRONJ) is still not fully understood. Retarded gingiva healing is the primary clinical manifestation in patients with MRONJ. In this study, we aimed to explore the relationship between autophagy and apoptosis in MRONJ gingival epithelium and search for a method to prevent this disease. First, we examined clinical samples from patients diagnosed with MRONJ and healthy controls, finding that autophagy-related markers MAP1LC3/LC3 and SQSTM1/p62 synchronously increased, thus suggesting that autophagic flux was suppressed in MRONJ. Moreover, mRNA sequencing analysis and TUNEL assay showed that the process of apoptosis was upregulated in patients and animals with MRONJ, indicating autophagy and apoptosis participate in the development of MRONJ. Furthermore, the level of autophagy and apoptosis in zoledronic acid (ZA)-treated human keratinocytes cell lines (HaCaT cells) was concentration dependent in vitro. In addition, we also found that RAB7 (RAB7, member RAS oncogene family) activator ML098 could rescue MRONJ gingival lesions in mice by activating the autophagic flux and downregulating apoptosis. To sum up, this study demonstrated that autophagic flux is impaired in the gingival epithelium during MRONJ, and the rescued autophagic flux could prevent the occurrence of MRONJ.Abbreviations: ACTB: actin beta; Baf-A1: bafilomycin A1; CASP3: caspase 3; CASP8: caspase 8; CT: computed tomography; DMSO: dimethyl sulfoxide; GFP: green fluorescent protein; HaCaT cells: human keratinocytes cell lines; H&E: hematoxylin and eosin; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MRONJ: medication-related osteonecrosis of the jaw; PARP: poly(ADP-ribose) polymerase; RAB7: RAB7, member RAS oncogene family; RFP: red fluorescent protein; SQSTM1/p62: sequestosome 1; TEM: transmission electron microscopy; ZA: zoledronic acid.

Adipose-Derived Stem Cells Promote Bone Coupling in Bisphosphonate-Related Osteonecrosis of the Jaw by TGF-ß1.

This study aimed to investigate molecularly targeted therapy to revive bone remodeling and prevent BRONJ by local adipose-derived stem cells (ADSCs) transplantation. Clinical samples of BRONJ and healthy jawbones were used to examine the bone coupling-related cells and TGF-ß1 expression. Bone coupling-related cells and TGF-ß1 expression were also assessed in BRONJ-like animal model to confirm the results in clinical samples. ADSCs were locally administered in vivo and the therapeutic effects were evaluated by gross observation, radiological imaging, and histological examination. Furthermore, ADSCs-conditioned medium (ADSCs-CM) and neutralizing antibody were applied to assess the effects of ADSCs-derived TGF-ß1 on restoring bone coupling in vivo. Osteoclast formation and resorption assays were performed to evaluate the effects of ADSCs-derived TGF-ß1 on ZA-treated pre-osteoclasts. Cell migration was performed to assess the effects of ADSCs-derived TGF-ß1 on patients' bone marrow stem cells (BMSCs). The number of osteoclasts, Runx2-positive bone-lining cells (BLCs) and TGF-ß1 expression were decreased in BRONJ and animal model jaw bone samples. These reductions were significantly rescued and necrotic jawbone healing was effectively promoted by local ADSCs administration in BRONJ-like animal models. Mechanistically, ADSCs-CM mainly contributed to promoting bone coupling, while TGF-ß1 neutralizing antibody in the conditioned medium inhibited these effects. Besides, osteoclastogenesis and patients' BMSCs migration were also rescued by ADSCs-derived TGF-ß1. Furthermore, bone resorption-released bone matrix TGF-ß1, together with ADSCs-derived TGF-ß1, synergistically contributed to rescuing BMSCs migration. Collectively, ADSCs promoted bone healing of BRONJ by TGF-ß1-activated osteoclastogenesis and BMSCs migration capacities.

Osteoclasts may contribute bone substitute materials remodeling and bone formation in bone augmentation.

Bone augmentation is increasingly important in implantology. Bone substitute materials exert essential roles during bone augmentation process. However, accelerating bone substitute materials remodeling and acquiring high bone architecture quality was still the challenges of bone augmentation. Accumulated studies had suggested osteoclasts is the key cell type to resorb bone or bone substitute materials. Our previous study and other studies suggested osteoclasts contributed to bone formation by promoting osteoblast function and facilitate angiogenesis. We hypothesized that bone substitute materials loaded osteoclastogenic cytokines or osteoclast progenitors will help to bone substitute materials rapid remodeling and subsequent bone formation. Our hypothesis could help to lessen long-term post-bone augmentation period and acquire better bone quality for osseointegration.

Effects of articular disc or condylar cartilage resection on mandibular growth in young rats.

OBJECTIVE: This study was aimed to compare the effects of articular disc and condylar cartilage resection on mandibular growth in Sprague Dawley rats. DESIGN: Eighty-four male Sprague Dawley rats (age = 4 weeks) were grouped according to the following procedures: group A (n = 21), exclusive surgical exposure of articular disc and condylar cartilage; group B (n = 21), exclusive surgical resection of articular disc; group C (n = 21), exclusive surgical resection of condylar cartilage; group D (n = 21), surgical resection of both articular disc and condylar cartilage. All surgery was performed in unilateral. One rat was killed in each group immediately after the surgery. Hematoxylin and eosin (H&E) staining was used to confirm the completely removal of the disc or cartilage. Five rats in the four groups were sacrificed in 1, 3, 6, and 9 weeks post-operation. The heights and lengths of the mandibles were measured and analyzed statistically. RESULTS: The mandibular height of group D (5.01 ± 0.25 mm) was statistically lower than group A (5.59 ± 0.17 mm) at 1 week post-operation. The height of group C (5.62 ± 0.26 mm) was significantly lower than group A (6.27 ± 0.31 mm) 3 weeks after surgery. The height of group B (6.38 ± 0.36 mm) was significantly lower than group A (6.95 ± 0.10 mm) 6 weeks after surgery. At 9 weeks post-operation, the mandibular heights in groups B, C, and D were lower than group A, group D was lower than group C, and group C was lower than group B. The lengths of the mandibles were not significantly decreased until 9 weeks post-operation in group D. CONCLUSIONS: The increase in mandibular height was interfered after either articular disc or condylar cartilage was resected, and mandibular height deficiency likely occurred earlier and more severely when cartilage was resected. However, the increase in mandibular length was barely interfered when either articular disc or condylar cartilage was resected.

Adipose-derived stem cells prevent the onset of bisphosphonate-related osteonecrosis of the jaw through transforming growth factor ß-1-mediated gingival wound healing.

BACKGROUND: Due to its complex pathogenesis and low clinical cure rate, bisphosphonate-related osteonecrosis of the jaw (BRONJ) poses a substantial challenge for oral and maxillofacial surgeons. Therefore, the treatment of BRONJ should focus on prevention. In clinical studies, primary wound closure can significantly reduce the incidence of BRONJ. Whether local stem cell transplantation can promote primary gingival healing in patients with a medication history and prevent BRONJ has not been reported. METHODS: In this study, animals were divided into a healthy group (non-drug treatment), a BP group, a hydroxyapatite (HA) group, and an adipose-derived stem cell (ADSC) group. All groups except the healthy group were treated with BPs and immunosuppressive drugs once per week for 8 weeks, simulating clinical use for the treatment of cancer patients with bone metastasis, to induce BRONJ-like animals. After the sixth drug treatment, the bilateral premolars were extracted in all groups. In contrast to the healthy and BP groups, the extraction sockets in the HA and ADSC groups were filled with HA or HA + ADSCs simultaneously post extraction to observe the preventive effect of ADSCs on the occurrence of BRONJ. At 2 and 8 weeks post extraction, animals from all groups were sacrificed. RESULTS: At 8 weeks post transplantation, ADSCs prevented the occurrence of BRONJ, mainly through accelerating healing of the gingival epithelium at 2 weeks post extraction. We also found that ADSCs could upregulate the expression of transforming growth factor ß1 (TGF-ß1) and fibronectin in tissue from animals with a medication history by accelerating gingival healing of the extraction socket. A rescue assay further demonstrated that TGF-ß1 and fibronectin expression decreased in TGF-ß1-deficient ADSC-treated animals, which partially abolished the preventive effect of ADSCs on the onset of BRONJ. CONCLUSION: ADSCs prevent the onset of BRONJ, mainly by upregulating the expression of TGF-ß1 and fibronectin to promote primary gingival healing, ultimately leading to bone regeneration in the tooth extraction socket. Our new findings provide a novel stem cell treatment for the prevention of BRONJ.

Histopathological features of hypertrophic bone mass of temporomandibular joint ankylosis (TMJA): An explanation of pathogenesis of TMJA.

Temporomandibular joint ankylosis (TMJA) is a severe organic disease with progressive limitation of the mouth opening. Histopathologically, a residual joint space is reported to consist of fibrous tissue and/or cartilage, indicating two types of interface (osteo-fibrous and osteo-chondral) of residual joint space. It is well known that adverse mechanical stress results in pathological changes of osteoarthritis and enthesopathy in these interfaces. What would happen pathologically in these interfaces of TMJA under repeated mandible movement has not been elucidated. Fourteen tissue samples of residual joint space and temporal and condylar bone were stained with hematoxylin and eosin and evaluated by collagen I and II immunohistochemistry. A pathological study of 14 TMJA patients showed that the residual joint space presented a fibrocartilage entheses structure and an articular cartilage structure. Moreover, these two structures were associated with pathological alterations of both osteoarthritis and enthesopathy, including degenerated and necrotized tissue, chondrocyte cloning, crack and fissure, various bone scleroses, and inflammatory granulation tissue. It is suggested that the pathological alterations of both osteoarthritis and enthesopathy occurred in TMJA, which hints at mechanical stress on TMJA development.