Bone formation in large/moderate gap after immediate implantation in response to different treatments: a pre-clinical study in the canine posterior mandible.

OBJECTIVES: This study aims to investigate different treatments on new bone formation around immediate implants in the canine posterior mandible with varying sized mesial-distal gap. MATERIALS AND METHODS: The 4th premolar and the 1st molar of six Labrador dogs were extracted from the mandible, and 4 dental implants were placed 1 mm below the level of the buccal bone crest. Moderate/large mesial-distal gaps between the implants and the sockets were treated with one of four methods and divided into the following groups: (1) the blank group, (2) the collagen membrane (CM) group, (3) the deproteinized bovine bone mineral (DBBM) group, and (4) the DBBM + CM group. Sequential fluorescent labeling was performed at 4, 8, and 10 weeks after the operation. After 12 weeks, the dogs were euthanized, and specimens were collected for micro-CT scanning and histological analysis. RESULTS: The survival rate of immediate implant was 100%. Micro-CT showed significant differences in bone mineral density (BMD) and bone volume fraction (BVF) among groups (P = 0.040, P = 0.009); other indicators were not significantly different among groups. Histological analysis showed the proportion of new bone formation and bone-to-implant contact were not significantly different among groups. No significant difference in bone reduction height around dental implant among four groups and varied mesial-distal gap size. CONCLUSION: Owing to the restricted sample size, this pilot study lacks conclusive findings. Within the limitation, this study demonstrated that although DBBM significantly increase BMD and BVF, the use of DBBM/CM didn't significantly improve bone formation and healing in extraction sockets around the implants in both moderate and large mesial-distal gap. CLINICAL RELEVANCE: The use of deproteinized bovine bone in conjunction with collagen is a common practice in immediate implantation procedures in the posterior mandible. However, there is a lack of conclusive evidence regarding the timing and circumstances under which they should be employed.

A Study of Two Novel Techniques for One-stage Closure of Chronic Oroantral Fistula and Sinus Floor Lift.

PURPOSE: This study aimed to compare two novel techniques for chronic oroantral fistula (OAF) closure combined with maxillary sinus floor elevation. MATERIALS AND METHODS: Ten patients who had implant installation needs but suffered from a chronic OAF were enrolled in the study from January 2016 to June 2021. The technique applied involved OAF closure and simultaneous sinus floor elevation by either a transalveolar or lateral window approach. Bone graft material evaluation results, postoperative clinical symptoms and complications were compared between the two groups. Student's t -test and χ 2 test were used to analyze the results. RESULTS: In this study, 5 patients with a chronic OAF were treated with the transalveolar approach (group I), and 5 were treated with the lateral window approach (group II). The alveolar bone height was significantly higher in group II than in group I ( P ＜0.001). The pain at 1 day ( P =0.018) and 3 days ( P =0.029) postoperatively and facial swelling at 7 days ( P =0.016) postoperatively were obviously greater in group II than in group I. There were no severe complications in either group. CONCLUSIONS: The techniques combined OAF closure with sinus lifting to reduce surgical frequency and risks. The transalveolar approach resulted in milder postoperative reactions, but the lateral approach could provide more bone volume.

Influence of Er:YAG laser irradiation on the outcomes of alveolar ridge preservation at the infected molar sites: a randomized controlled trial.

BACKGROUND: The purpose of this study was to investigate the socket healing outcome after alveolar ridge preservation at infected molar sites using an erbium-doped yttrium aluminium garnet (Er:YAG) laser. METHODS: Eighteen patients who needed molar extraction and exhibited signs of infection were included and allocated into either the laser group or the control group. Er:YAG laser irradiation for degranulation and disinfection was performed with alveolar ridge preservation (ARP) in the laser group. Traditional debridement with a curette was performed in the control group. Two months after ARP, bone tissue samples were harvested at the time of implant placement for histological analysis. Assessment of dimension changes in alveolar bone was conducted by superimposing two cone-beam computed tomography (CBCT) scans taken at baseline and two months after extraction. RESULTS: Histologically, after two months of healing, Er:YAG laser treatment resulted in more newly formed bone (laser: 17.75 ± 8.75, control: 12.52 ± 4.99, p = 0.232). Moreover, greater osteocalcin (OCN) positive expression and lower runt-related transcription factor 2 (RUNX-2) positive expression were detected in the laser group. However, no statistically significant difference was observed between the two groups. The difference in the vertical resorption of the buccal bone plate was statistically significant between groups (laser: -0.31 ± 0.26 mm, control: -0.97 ± 0.32 mm, p < 0.05). Major changes in ridge width were observed at 1 mm below the bone crest. However, the differences between groups were not significant (laser: -0.36 ± 0.31 mm, control: -1.14 ± 1.24 mm, p = 0.171). CONCLUSIONS: ARP with Er:YAG laser irradiation seemed to improve bone healing by regulating osteogenesis-related factor expression in the early stage at infected sites. TRIAL REGISTRATION: The trial was registered on the Chinese Clinical Trial Registry Platform ( https://www.chictr.org.cn/ ) (registration number: ChiCTR2300068671; registration date: 27/02/2023).

[Progress in Application of Concentrated Growth Factor in Oral Tissue Regeneration].

Tissue regeneration is an important engineering method for the treatment of oral soft and hard tissue defects.Growth factors,as one of the three elements of tissue regeneration,are a necessary condition for tissue regeneration.Concentrated growth factor(CGF)is a new generation of blood extract prepared by changing the centrifugal speed on the basis of the preparation of platelet-rich plasma(PRP)and platelet-rich fibrin(PRF).It contains abundant growth factors and a fibrin matrix with a three-dimensional network structure,being capable of activating angiogenesis and promoting tissue regeneration and healing.CGF has been widely used in the repair and regeneration of oral soft and hard tissues.This paper introduces the preparation and composition of CGF and reviews the application of CGF in oral implantation and the regeneration of oral bone tissue,periodontal tissue,and dental pulp tissue.

Quantitative Segmentation Analysis of the Radiological Changes by Using ITK-SNAP: Risk Assessment of the Severity and Recurrence of Medication-related Osteonecrosis of the Jaw.

Background and purpose: Medication-related osteonecrosis of the jaw (MRONJ) severely impairs patients' quality of life and is remarkably refractory to treatment. There are lots of studies about identification of the radiographic features of MRONJ, yet reports about quantitative radiographic analysis for the risk assessment of the severity and recurrence of MRONJ are rarely heard. The aim of this study was to investigate the volumes of osteolytic lesions and radiodensity values of osteosclerotic lesions in MRONJ patients by using ITK-SNAP for severity prediction and prognosis evaluation. Materials and methods: Of 78 MRONJ patients (78 lesions) involved in this retrospective study, 53 were presented as osteolytic lesions and 25 were presented as osteosclerotic changes alone. Comprehensive CBCT images, demographics and clinical data of patients were investigated. The volumetric analysis and radiodensity measurement were performed by ITK-SNAP. SPSS 25.0 were used for statistical analysis. Results: The osteolytic lesion volumes in MRONJ patients receiving intravenous bisphosphonates (P=0.004) and patients without osteoporosis (P=0.027) were significantly large. No significant correlation between the volumes and bisphosphonates duration was found (P=0.094). The radiodensity values of osteosclerotic lesions was significantly correlated with bisphosphonates duration (P=0.040). The surrounding area of post-surgical lesions in MRONJ patients with recurrence showed significantly great radiodensity values (P=0.025). No significant correlation between the radiodensity values and the transformation from osteosclerotic lesions to osteolytic lesions was observed (P=0.507). Conclusion: MRONJ patients receiving intravenous bisphosphonates develop into large volumes of osteolytic lesions more easily. Long-term bisphosphonates duration is possibly related with higher bone density of osteosclerotic lesions, while higher density is not associated with the transformation from osteosclerotic lesions to osteolytic lesions. A rise of bone mineral density nearby post-surgical lesions is probably a predictor for MRONJ recurrence.

Timing of force application on buccal tooth movement into bone-grafted alveolar defects: A pilot study in dogs.

INTRODUCTION: The aim of this pilot study was to evaluate the effect of the timing of postoperative orthodontic force application on bone remodeling during tooth movement into surgical alveolar defects with bone grafts in beagle dogs. METHODS: Six beagle dogs underwent surgery for buccal dehiscence-type defects (width, 5 mm; height, 6 mm) on the distal root of maxillary second premolars bilaterally for 12 defects. After 1-month healing, bone-augmentation procedures were undertaken at the dehiscence defects. The second premolars were protracted buccally for 6 weeks into the surgical sites immediately (F-0), at 4 weeks (F-4), or 8 weeks (F-8) after grafting. Orthodontic tooth movement was monitored using digital models. Remodeling of alveolar bone was evaluated by histology, histomorphometry, immunohistochemistry, microcomputed tomography, and fluorescence microscopy. RESULTS: Group F-0 showed significant expansion (mean, 2.42 mm) and tipping (mean, 9.03°) after completing orthodontic tooth treatment. The vertical bone defect was significantly lower in groups F-4 and F-8 than that in group F-0 (mean, 2.1, 2.7, and 4.5 mm, respectively). In group F-4, the formation of new bone and mineralization were significantly greater than those in groups F-0 and F-8 (P <0.05). Group F-4 showed a minimal amount of bone-material remnants. Immunohistochemistry showed the highest expression of collagen-1 and osteopontin in group F-4, followed by group F-8 and group F-0, which demonstrated high osteoblast activity and enhanced bone remodeling in group F-4. CONCLUSIONS: Orthodontic force application at 4 weeks after an augmentation procedure provided the best functional stimulation for an alveolar bone graft. This strategy enhanced new-bone regeneration and degradation of bone substitutes and, eventually, promoted bone remodeling in the bone-grafted area.

Novel mutations identified in patients with tooth agenesis by whole-exome sequencing.

OBJECTIVES: To identify potentially pathogenic mutations for tooth agenesis by whole-exome sequencing. SUBJECTS AND METHODS: Ten Chinese families including five families with ectodermal dysplasia (syndromic tooth agenesis) and five families with selective tooth agenesis were included. Whole-exome sequencing was performed using genomic DNA. Potentially pathogenic mutations were identified after data filtering and screening. The pathogenicity of novel variants was investigated by segregation analysis, in silico analysis, and functional studies. RESULTS: One novel mutation (c.441_442insACTCT) and three reported mutations (c.252delT, c.463C>T, and c.1013C>T) in EDA were identified in families with ectodermal dysplasia. The novel EDA mutation was co-segregated with phenotype. A functional study revealed that NF-κB activation was compromised by the identified mutations. The secretion of active EDA was also compromised detection by western blotting. Novel Wnt10A mutations (c.521T>C and c.653T>G) and EVC2 mutation (c.1472C>T) were identified in families with selective tooth agenesis. The Wnt10A c.521T>C mutation and the EVC2 c.1472C>T mutation were considered as pathogenic for affecting highly conserved amino acids, co-segregated with phenotype and predicted to be disease-causing by SIFT and PolyPhen2. Moreover, several reported mutations in PAX9, Wnt10A, and FGFR3 were also detected. CONCLUSIONS: Our study expanded our knowledge on tooth agenesis spectrum by identifying novel variants.

Human Stem Cells Overexpressing miR-21 Promote Angiogenesis in Critical Limb Ischemia by Targeting CHIP to Enhance HIF-1α Activity.

Critical limb ischemia (CLI) is a severe blockage in the arteries of the lower extremities. However, the effective and optimal treatment for CLI remains to be elucidated. Previous therapeutic research is mainly focused on proangiogenic growth factors administrations. Recently, miR-21 has been revealed to play a crucial role in angiogenesis. Thus, we hypothesize that miR-21 over-expression in human umbilical cord blood-derived mesenchymal stem cells (UCBMSCs) can effectively treat CLI. Herein, UCBMSCs were transduced with lentivirus-miR-21-Luciferase (Lenti-miR-21) or lentivirus- LacZ-Luciferase (Lenti-LacZ). The results indicated that miR-21 induced UCBMSCs proliferation, migration, and angiogenesis in vitro. Subsequently, general observation and laser Doppler perfusion imaging were introduced to detect perfusion in muscles of CLI-nude mice on 1, 4, 7, 14, and 28 day postoperation. There was a significant improvement in blood vessels of the ischemic limb in Lenti-miR-21 group at 7 day compared with the saline or Lenti-LacZ groups. At 28 day, histological analysis confirmed that UCBMSCs over-expressing miR-21 increased neovascularization in CLI. Furthermore, carboxyl terminus of Hsc70-interacting protein (CHIP) was found to be the target gene for miR-21-mediated activation of hypoxia-inducible factor 1α (HIF-1α) in UCBMSCs. In summary, our study demonstrated that over-expressing miR-21 in UCBMSCs could improve neovascularization in CLI through enhancing HIF-1α activity by targeting CHIP, which may hold great therapeutic promise in treating CLI.

Long-term success of dental implant-supported dentures in postirradiated patients treated for neoplasms of the maxillofacial skeleton: a retrospective study.

OBJECTIVES: The reconstruction of oral function in irradiated patients with craniofacial tumors is a significant challenge. The aim of this study was to detect long-term success of dental implant-supported dentures in postirradiated patients treated for neoplasms of the maxillofacial skeleton. MATERIALS AND METHODS: From 2004 to 2011, 36 irradiated patients underwent oral function reconstruction using implant-supported prostheses. Bone augmentation was completed using vascularized bone grafts in 22 patients. Fourteen patients were treated by hyperbaric oxygen therapy (HBO). A total of 198 dental implants were used in jaw rehabilitation. After loading, implant success rates, biological and prosthetic complications, patient satisfaction, and psychological changes were recorded. RESULTS: Bone augmentation of the jaw was successful and vascularized grafts provided an additional vascular supply in compromised irradiated tissue. Rehabilitation was successful in all of the patients after loading. Thirty-eight dental implants failed, and 35 implants were removed. The success rate of the implants was 93.6 % for 10 years after loading. It was not a significant difference in implant success rate between the HBO group and the other groups. The prosthodontic maintenance results and complication rates showed that patients required intervention 0.19 times per year. All patients were satisfied with the oral restoration results. CONCLUSION: The restoration of oral function in radiotherapy patients with tumor resection using implant-supported prostheses is a viable treatment option. CLINICAL RELEVANCE: Either alone or in combination with HBO, dental implant-supported prostheses can be used an effective therapeutic approach for irradiated patients with oral function reconstruction.

Oral Rehabilitation of Adult Edentulous Siblings Severely Lacking Alveolar Bone Due to Ectodermal Dysplasia: A Report of 2 Clinical Cases and a Literature Review.

The oral conditions of adult edentulous patients with ectodermal dysplasia (ED) often lead to decreased physical and psychological health, and the negative effects can become as extreme as social and psychological isolation. However, restoring oral function of adult edentulous patients with ED using zygomatic implants (ZIs) or conventional implants (CIs) remains challenging for dentists because of the severe atrophy of these patients' alveolar ridges. This report describes 2 cases of adult edentulous siblings with ED; they exhibited severe alveolar bone atrophy and were treated with ZIs and CIs as bases to augment the bone in their anterior jaws. For these patients, bone augmentation was completed with an autogenous fibular graft. Although there was mild evidence of bone graft resorption in the maxilla, the bone augmentation procedures were successful in the 2 patients. Effective osseointegration of the implants was obtained. After placement, the functional and esthetic results of the oral rehabilitation were acceptable. More importantly, restoration of the patients' oral function enhanced their self-confidence and self-esteem. Therefore, restoring oral function in adult patients with ED and edentulous jaws using ZIs and CIs as the bases for bone augmentation is an effective approach.

A retrospective 3- to 5-year study of the reconstruction of oral function using implant-supported prostheses in patients with hypohidrotic ectodermal dysplasia.

The aim of this study was to evaluate oral function rehabilitation in patients with hypohidrotic ectodermal dysplasia (HED) using implant-supported prostheses based on bone augmentation. From September 2005 and March 2009, 25 HED patients were chosen for clinical data analysis in this study. The criteria for patient selection included the following: the display of clinical features of HED, the number of congenitally missing teeth (>5), the patient age (>16 years), the patient's willingness, and the patient's tolerance for bone graft surgery and implant placement. Follow-up evaluations were initiated from the time of implant prosthetic placement and scheduled annually for 3-5 years. The effects of oral function reconstruction were assessed based on the cumulative survival and success rates of implants, the health of the peri-implant area, and the degree of patient satisfaction. Twenty-five HED patients received 169 conventional implants and 10 zygomatic implants (179 total implants). During 3-5 years of post-loading evaluations, 5 of the 179 implants failed and 3 implants were removed. The 3-year success and cumulative survival rates were 97.2% and 98.3%, respectively. Furthermore, periodontal probing and radiographic assessments showed that the 3-year incidence of peri-implantitis was 4.5%. Finally, HED patients expressed high degrees of satisfaction with their facial contours, masticatory function, pronunciation ability, and comfort with the implant-supported prostheses. The results of this 3- to 5-year retrospective study indicate that the oral function of HED patients can be effectively reconstructed using bone augmentation and implant-supported prostheses; however, longer term results are warranted in the future.

Bioinspired polysaccharide-based nanocomposite membranes with robust wet mechanical properties for guided bone regeneration.

Polysaccharide-based membranes with excellent mechanical properties are highly desired. However, severe mechanical deterioration under wet conditions limits their biomedical applications. Here, inspired by the structural heterogeneity of strong yet hydrated biological materials, we propose a strategy based on heterogeneous crosslink-and-hydration (HCH) of a molecule/nano dual-scale network to fabricate polysaccharide-based nanocomposites with robust wet mechanical properties. The heterogeneity lies in that the crosslink-and-hydration occurs in the molecule-network while the stress-bearing nanofiber-network remains unaffected. As one demonstration, a membrane assembled by bacterial cellulose nanofiber-network and Ca2+-crosslinked and hydrated sodium alginate molecule-network is designed. Studies show that the crosslinked-and-hydrated molecule-network restricts water invasion and boosts stress transfer of the nanofiber-network by serving as interfibrous bridge. Overall, the molecule-network makes the membrane hydrated and flexible; the nanofiber-network as stress-bearing component provides strength and toughness. The HCH dual-scale network featuring a cooperative effect stimulates the design of advanced biomaterials applied under wet conditions such as guided bone regeneration membranes.

Harmonizing Thickness and Permeability in Bone Tissue Engineering: A Novel Silk Fibroin Membrane Inspired by Spider Silk Dynamics.

Guided bone regeneration gathers significant interest in the realm of bone tissue engineering; however, the interplay between membrane thickness and permeability continues to pose a challenge that can be addressed by the water-collecting mechanism of spider silk, where water droplets efficiently move from smooth filaments to rough conical nodules. Inspired by the natural design of spider silk, an innovative silk fibroin membrane is developed featuring directional fluid transportation via harmoniously integrating a smooth, dense layer with a rough, loose layer; conical microchannels are engineered in the smooth and compact layer. Consequently, double-layered membranes with cone-shaped microporous passageways (CSMP-DSF membrane) are designed for in situ bone repair. Through extensive in vitro testing, it is noted that the CSMP-DSF membrane guides liquid flow from the compact layer's surface to the loose layer, enabling rapid diffusion. Remarkably, the CSMP-DSF membrane demonstrates superior mechanical properties and resistance to bacterial adhesion. When applied in vivo, the CSMP-DSF membrane achieves results on par with the commercial Bio-Gide collagen membranes. This innovative integration of a cross-thickness wetting gradient structure offers a novel solution, harmonizing the often-conflicting requirements of material transport, mechanical strength, and barrier effectiveness, while also addressing issues related to tissue engineering scaffold perfusion.

Role of periosteum in alveolar bone regeneration comparing with collagen membrane in a buccal dehiscence model of dogs.

To investigate the role of periosteum on the treatment of buccal dehiscence defects comparing with collagen membrane in canine model. Bilateral dehiscence-type defects at the buccal side on the distal root of the lower 3rd/4th premolars were created in six beagle dogs with a total of 24 defects and assigned into three groups: Group A: blood clot in an untreated defect; Group B: deproteinized bovine bone material (DBBM) covered with an absorbable membrane; Group C: DBBM covered with the periosteum. The structural parameters for trabecular architecture and vertical bone regeneration were evaluated. Histological and histomorphometric evaluation were carried out to observe new bone formation and mineralization in the graft site. Immunohistochemical analysis was performed to identify the expression of osteopontin (OPN) and osteocalcin (OCN) at postoperative 3 months. Group C achieved greater vertical alveolar bone gain than that of group A and group B. The periosteum-covered group showed significantly greater new bone formation and accelerated mineralization. The greater immunolabeling for OPN and OCN was observed in group C than in group A. Periosteal coverage has explicit advantages over collagen membranes for the quality and quantity of new bone regeneration in dehiscence defects repairing.

Designing nanohesives for rapid, universal, and robust hydrogel adhesion.

Nanoparticles-based glues have recently been shown with substantial potential for hydrogel adhesion. Nevertheless, the transformative advance in hydrogel-based application places great challenges on the rapidity, robustness, and universality of achieving hydrogel adhesion, which are rarely accommodated by existing nanoparticles-based glues. Herein, we design a type of nanohesives based on the modulation of hydrogel mechanics and the surface chemical activation of nanoparticles. The nanohesives can form robust hydrogel adhesion in seconds, to the surface of arbitrary engineering solids and biological tissues without any surface pre-treatments. A representative application of hydrogel machine demonstrates the tough and compliant adhesion between dynamic tissues and sensors via nanohesives, guaranteeing accurate and stable blood flow monitoring in vivo. Combined with their biocompatibility and inherent antimicrobial properties, the nanohesives provide a promising strategy in the field of hydrogel based engineering.

Repair of critical-sized rat calvarial defects using genetically engineered bone marrow-derived mesenchymal stem cells overexpressing hypoxia-inducible factor-1α.

The processes of angiogenesis and bone formation are coupled both temporally and spatially during bone repair. Bone marrow-derived mesenchymal stem cells (BMSCs) have been effectively used to heal critical-size bone defects. Enhancing their ability to undergo angiogenic and osteogenic differentiation will enhance their potential use in bone regeneration. Hypoxia-inducible factor-1α (HIF-1α) has recently been identified as a major regulator of angiogenic-osteogenic coupling. In this study, we tested the hypothesis that HIF-1α gene therapy could be used to promote the repair of critical-sized bone defects. Using lentivirus-mediated delivery of wild-type (HIF) or constitutively active HIF-1α (cHIF), we found that in cultured BMSCs in vitro, HIF and cHIF significantly enhanced osteogenic and angiogenic mRNA and protein expression when compared with the LacZ group. We found that HIF-1α-overexpressing BMSCs dramatically improved the repair of critical-sized calvarial defects, including increased bone volume, bone mineral density, blood vessel number, and blood vessel area in vivo. These data confirm the essential role of HIF-1α modified BMSCs in angiogenesis and osteogenesis in vitro and in vivo.

[The hemostasis effect and cell compatibility of a chitosan-calcium alginate-laponite nanosheet composite membrane: in vitro and in vivo evaluation].

PURPOSE: To explore the feasibility of a chitosan-calcium alginate-laponite nanosheet composite membrane being used as a new hemostatic membrane for wounds in oral cavity. METHODS: The composite membrane was prepared in a layered fashion: the lower layer of chitosan membrane was made through self-evaporation and the upper layer of calcium alginate-laponite nanosheet sponge was made via freeze-drying. The microstructure of the composite membrane was observed under scanning electron microscopy (SEM) and transmission electron microscopy (TEM). X-ray diffraction was used as a means of identifying the compounds. Clotting time of composite membrane, medical gauze and Chitin dressing in vitro was measured by the plate method for blood coagulation. Cytotoxicity tests were quantified through co-culturing NIH/3T3 cells with chitosan-calcium alginate extract, composite hemostatic membrane extract and DMEM. Superficial buccal mucosal wound models and tooth extraction models were created on beagles dogs, the hemostatic effect and adhesion to oral mucosa were evaluated on these models. Statistical analysis was performed using SPSS 18.0 software package. RESULTS: The composite hemostatic membrane consisted of double-layer in microstructure, the upper layer was a foam layer consisting of calcium alginate and laponite nanosheet, the substratum was formed by uniform chitosan film. X-ray diffraction results showed that laponite nanosheet can be found in the composite membrane. Coagulation test showed that the composite hemostatic membrane group significantly shortened clotting time in vitro compared to pure calcium alginate group, commercial hemostatic membrane and blank control group(P＜0.001). CCK-8 test of NIH/3T3 cell showed that there was no significant difference in absorbance between the experimental group, negative control group and blank control group (P＞0.05). In addition, composite hemostatic membrane displayed a good hemostatic effect and strong adhesion to oral mucosa in animal models. CONCLUSIONS: The composite hemostatic membrane showed great hemostatic effects and had no significant cytotoxicity, which has the potential for clinical application as hemostatic membrane for wounds in oral cavity.

[Effect evaluation on different treatment methods of the gap of immediate implantation in canine posterior mandible].

PURPOSE: This study was aimed to explore the formation of new bone after different methods of filling the gap between the extraction socket and the implant in immediate implantation of the canine mandibular molar area. METHODS: Six Labrador dogs aged 1.5-2.0 years were used as the experimental subjects. The fourth premolar and the first molar were extracted from the mandible of each dog, and then 4 dental implants (Astra Tech, 4.0 mm × 10 mm) were implanted respectively. The mesial and distal gaps between dental implants and the walls of extraction socket were treated in three methods: blank group (group NN), gelatin sponge with colloidal silver (Gelatamp) group (group EN), Gelatamp + absorbable collagen membrane (CM) group (group EG). At 12 weeks, the dogs were euthanized, and specimens were collected for micro-CT scanning and histological analysis. SPSS 25.0 software package was used for statistical analysis. RESULTS: The survival rate at 12 weeks after implantation was 100%. Micro-CT scan results showed no significant differences in new bone height, bone mineral density (BMD), bone volume fraction (BV/TV), bone surface area bone volume ratio (BS/TV), bone trabecular thickness (Tb.Th), bone trabecular number (Tb.N) and bone trabecular separation (Tb.Sp) among different groups. Histological analysis showed no significant differences in the area of new bone formation and bone-implant contact (BIC). CONCLUSIONS: After different treatments are performed on the gap between implants and extraction sockets, Gelatamp alone or in combination with CM has no significant effect on new bone formation, BIC, BMD, BV/TV, BS/TV, Tb.Th, Tb.N and Tb.Sp around implant.

[Effect of rat allogeneic BMSCs-Bio-Oss-bFGF compound on tooth extraction healing: a micro-CT study].

PRUPOSE: To investigate the effect of a compound of BMSCs-Bio-Oss-bFGF on microstructure of extraction sockets in rats. METHODS: Bone mesenchymal stem cells (BMSCs) were isolated from bone marrow of 3-week SD rats by adherent method. Maxillary posterior teeth of 36 6-week SD rats were extracted and materials were implanted into sockets according to grouping. The rats were divided into 4 groups: compound group with implanting BMSCs-Bio-Oss-bFGF compound, powder group with implanting Bio-Oss, BMSCs group with implanting BMSCs, and control group without implanting any materials. The sockets were scanned by micro-CT 4 weeks, 12 weeks and 24 weeks after implantation. Two-way ANOVA was used to assess whether there was significant difference between groups with GraphPad Prism 6.0 software package. RESULTS: There was no significant difference among groups in bone mineral density (BMD), trabecular separation(Tb.Sp), trabecular thickness(Tb.Th), degree of anisotropy(DA), and trabecular number(Tb.N) 4 weeks after implantation. By 12 weeks, BMD of compound group was significantly greater than those of BMSCs group, powder group and control group (P＜0.05), and significantly greater than those of powder group and control group at 24 weeks (P＜0.05). Tb.Th of compound group was significantly greater than that of BMSCs group at 12 and 24 weeks(P＜0.05). DA had no significant difference among groups at 4, 12, and 24 weeks (P＞0.05). Tb.Sp of compound group was significantly smaller than those of powder group, BMSCs group and control group at 24 weeks(P＜0.05). Tb.N of compound group was significantly greater than those of BMSCs group and control group(P＜0.05). CONCLUSIONS: The compound of rat allogeneic BMSCs-Bio-Oss-bFGF improves socket healing.