Alveolar ridge preservation: why, when and how

Current State of Clinical Trials Regarding Alveolar Bone Grafting

ObjectivesAlveolar ridge defects develop because of surgery, trauma, infection, or congenital malformations. Alveolar ridge defects can be resolved using an osseous replacement. The primary outcomes of osseous replacement are the maintenance of contour; the elimination of dead space, the reduction of postoperative infection; and the increase in bony and soft tissue healing. Recent research shows promising developments in dental bone grafts. This review presents the results of several clinical trials and provides updates on current alveolar bone grafting.DesignIn May 2023, we searched Clinicaltrials.gov for interventional clinical trials related to alveolar bone grafting. A total of 66 clinical trials were included using Boolean Operators AND, OR, NOT we used the "advanced search" option with the search terms [Alveolar Bone Grafting] OR [Ridge Preservation] OR [Dental Bone Grafting] OR [Ridge Augmentation]. Reviewed publications are summarized.Results28 out of the 66 trials were successfully completed. None of the trials had offered an invitation to enroll, and only one was terminated. Autograft was the most prevalent kind of grafting, at 28 out of 66, more than twice as prevalent as allograft, which ranked second at 12 out of 66.Conclusionthis study shows a lack of variety in location, low results provided, and low clinical trials regarding bone rejection. The focus of published trials was mainly on cleft palate rehabilitation using secondary alveolar bone grafting, and the usage of L-prf, rh-FGF-2, rhBMP2, and hyaluronic acid in association with alveolar bone grafting showed remarkable results concerning bone's osteoconduction, osteoinduction, and osteogenesis.

A New Approach for Reconstruction of Severe Horizontal Atrophy of the Posterior Mandible Using "The Honeycomb Technique": A 10-14 Year Follow-Up Retrospective Study

Background: Autogenous bone grafting has long been the standard for augmenting bone prior to implant placement in atrophic ridges. However, innovative techniques are continually sought to enhance outcomes. This study introduces the honeycomb technique for horizontal bone augmentation in edentulous posterior mandibular ridges, presenting the methodology and long-term follow-up results of this novel approach. Methods: This study includes healthy patients with moderate to severe horizontal atrophy in posterior mandibular regions who underwent bone augmentation using the honeycomb technique and were followed up for a period of 10 to 14 years. The patients had orthoradiographs immediately post-surgery and underwent regular clinical and radiographic evaluations. Computed tomography at four months assessed the bone gain, followed by reentry for implant insertion and evaluation of the bone volume and quality. Fixed prosthesis-supported dental implants were placed four months post-insertion. The survival and success of the dental implants were evaluated based on the acceptable clinical and radiographic criteria. Results: A cohort of 23 patients (17 women, 6 men, mean age 47 years) underwent bone augmentation at 39 sites, with follow-up ranging from 10 to 14 years. The procedure demonstrated a 95-100% success rate with minimal morbidity and horizontal bone gain averaging 3-8 mm. Partial graft exposure occurred in two cases but was successfully managed without compromising augmentation. A total of 103 implants were placed in the augmented sites in 37 sites. The long-term survival of the dental implants was confirmed based on clinical and radiographic evaluation, with minimal marginal bone loss observed during the extended follow-up period. Conclusions: The honeycomb technique proves effective in horizontal bone augmentation of atrophic ridges in posterior mandibular defects. The satisfactory long-term outcomes validate its potential as a valuable addition to bone augmentation strategies preceding implant placement.

Characterization of craniofacial tissue aging in genetically diverse HET3 male mice with longevity treatment of 17-alpha estradiol

OBJECTIVE

The objective of our study was to 1) characterize craniofacial tissue aging in the new, genetically diverse HET3 mouse model; and 2) ascertain whether increased longevity with 17-alpha estradiol (17αE2) treatment in male mice also improved the health of these tissues. The HET3 mice are a four-strain cross preferred and recommended by the National Institute of Aging to identify longevity treatments and test their ability to reduce age-related pathologies. Previous reports demonstrated increased longevity in male, but not female, HET3 mice with 17αE2 administration.

DESIGN

Male mice were raised to approximately 8 months (young), 16 months (middle-aged), and 25 months (old). Middle-aged and old mice were administered a diet supplemented with 17αE2 for 19 weeks. We quantified craniofacial tissue volume and density changes with micro-computed tomography followed by histology.

RESULTS

Micro-CT showed that the alveolar bone volume and density did not change with age or treatment. Enamel volume and density changed with age but not treatment. Histology revealed region-specific degeneration of periodontal ligaments (PDLs) with age. Cellular cementum demonstrated age-related density decreases but no change in volume. However, cementum volume and density increased with 17αE2 treatment. Dentin volume increased with age whereas density decreased with age, which were attenuated by 17αE2 treatment.

CONCLUSIONS

The HET3 mice present an excellent model with which to study the heterogeneous nature of tooth aging and the effects of longevity interventions. We provide novel data on how 17αE2 improves healthspan by modifying age-related changes in the molar dentin and cementum of male mice.

A Systematic Review and Meta-Analysis to Find Out the Efficacy of Socket Preservation Techniques in Adults in Split-Mouth Randomized Controlled Trials

Alveolar ridge preservation has been practiced for a long time, yet it is not a standard component of post-extraction care. Post-extraction bone loss is an inevitable consequence, but successful implant treatment planning requires adequate bone and soft tissue coverage. Delayed implant placement and fixed partial dentures may significantly benefit from alveolar ridge preservation. This systematic review aimed to gather evidence on alveolar ridge preservation using split-mouth randomized controlled trials. The study protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO) with the registration ID number CRD42020177085. A comprehensive literature search was conducted using electronic databases and manual searches, yielding 4,654 results, from which 10 eligible studies were selected. These studies included a total of 101 participants and 202 extraction sockets. Meta-analysis was conducted using the fixed and random effects generic inverse variance method with the RevMan 5.3 software (Cochrane Collaboration, London, UK). The analysis revealed that the mean bone dimensional change in width at three months was 1.99 (0.63, 3.35), while the vertical height changes for the buccal and lingual plates were 1.13 (0.57, 1.70) and 0.46 (-0.06, 0.98), respectively. The pooled mean for differences in width at six months favored alveolar ridge preservation, though the internal vertical height changes at six months provided contradictory results. The findings indicate that socket preservation techniques help reduce alveolar bone loss. However, the conclusions must be interpreted cautiously, as further research with long-term randomized controlled trials is necessary to evaluate outcomes beyond bone loss.

Autologous platelet concentrates in alveolar ridge preservation: A systematic review with meta-analyses

In order to evaluate the therapeutic advantages of various autologous platelet concentrates (APC) as a single biomaterial during alveolar ridge preservation (ARP), a systematic review with meta-analyses was conducted. PubMed, EMBASE, Web of Science, and Scopus were screened for randomized controlled trials (RCTs) that were released prior to 2024. The selected papers compared an APC with either unassisted healing (blood clot) or another biomaterial during ARP (third molars were not included). The outcome parameters included alveolar bone dimension alterations, soft tissue healing, and post-op pain intensity. The search yielded 35 papers (33 studies), one applying platelet-rich plasma (PRP), six using plasma rich in growth factors (PRGF), and 28 using leukocyte- and platelet-rich fibrin (L-PRF). These studies showed a large heterogeneity (e.g., outcome parameters, timing, surgical approach, and inclusion criteria), which hindered drawing strong conclusions. In most studies, however, ARP with PRP, PRGF, and L-PRF alone produced faster soft tissue healing, less post-extraction pain, less alveolar ridge resorption, more socket bone fill, and a higher bone density when compared to unassisted (spontaneous) healing. The ultimate benefit appears to be significantly influenced by the surgical approach. Limited literature exists comparing APC with other biomaterials for ARP, resulting in inconclusive data. APC application for ARP is a promising strategy to improve soft and hard tissue healing and reduce post-extraction pain.

After Extraction, Upper Premolars Undergo Programmed Socket Collapse with Development of Cavitations Rather than Complete Socket Healing: A Radiological Study

The alveolar ridge undergoes a loss in volume and atrophy after tooth extraction. Understanding the wound healing and bone regeneration process after tooth extraction is a key factor in the insertion of dental implants. Therefore, the aim of the present study was to analyze the socket healing process after the extraction of upper premolars based on cone beam computed tomography (CBCT) over six months. Special focus was placed on the morphological changes in the alveolar crest and within the socket. A retrospective analysis of patients in need of tooth extraction in the upper premolar region was performed in this study. All patients received flapless tooth extraction under local anesthesia and CBCT immediately after tooth extraction. Further CBCT analysis was performed after three months for the first group (n = 18) and after six months for the second group (n = 18). The results showed that all sockets underwent an inward movement of the defect walls towards the defect center, resulting in reduced total alveolar ridge volume and defect volume. This result was observed after three months and persisted after six months. The inward movement was quantified as a vertical socket collapse of up to 30.1 ± 9.0% after three months and 34.3 ± 6.7% after six months. The horizontal inward movement was quantified as a buccal socket collapse of 47.7 ± 12.3% after three months and 55.7 ± 29.1% after six months. New bone formation within the socket was evident, especially in the occlusal part of the socket. Additionally, bone formation was primarily observed as bone apposition along the socket walls and did not reach the defect center in most cases. The combination of socket collapse and bone apposition led to the formation of cavitations inside the socket that were mostly localized under the occlusal part. These novel findings with respect to socket collapse and formation of cavitation represent a paradigm shift and call for reconsidering the current understanding of socket healing. Based on the data, socket healing should be understood as a patient-specific process that requires 3D radiographic analysis for planning dental implants.

The Microbial Diversity and Biofilm Characteristics of d-PTFE Membranes Used for Socket Preservation: A Randomized Controlled Clinical Trial

BACKGROUND

Understanding microbial colonization on different membranes is critical for guided bone regeneration procedures such as socket preservation, as biofilm formation may affect healing and clinical outcomes. This randomized controlled clinical trial (RCT) investigates, for the first time, the microbiome of two different high-density polytetrafluoroethylene (d-PTFE) membranes that are used in socket preservation on a highly molecular level and in vivo.

METHODS

This RCT enrolled 39 participants, with a total of 48 extraction sites, requiring subsequent implant placement. Sites were assigned to two groups, each receiving socket grafting with a composite bone graft (50% autogenous bone, 50% bovine xenograft) and covered by either a permamem® (group P) or a Cytoplast™ (group C). The membranes were removed after four weeks and analyzed using scanning electron microscopy (SEM) for bacterial adherence, qPCR for bacterial species quantification, and next-generation sequencing (NGS) for microbial diversity and composition assessment.

RESULTS

The four-week healing period was uneventful in both groups. The SEM analysis revealed multispecies biofilms on both membranes, with membranes from group C showing a denser extracellular matrix compared with membranes from group P. The qPCR analysis indicated a higher overall bacterial load on group C membranes. The NGS demonstrated significantly higher alpha diversity on group C membranes, while beta diversity indicated comparable microbiota compositions between the groups.

CONCLUSION

This study highlights the distinct microbial profiles of two d-PTFE membranes during the four-week socket preservation period. Therefore, the membrane type and design do, indeed, influence the biofilm composition and microbial diversity. These findings may have implications for healing outcomes and the risk of infection in the dental implant bed and should therefore be further explored.

Magnesium Membrane Shield Technique for Alveolar Ridge Preservation: Step-by-Step Representative Case Report of Buccal Bone Wall Dehiscence with Clinical and Histological Evaluations

BACKGROUND/OBJECTIVES

Despite the increased use of new resorbable magnesium membranes, there are no reported cases or studies on the use of resorbable magnesium membranes in combination with bone grafts for alveolar ridge preservation (ARP) in cases with severe buccal bone wall dehiscence. This case report aimed to evaluate the effectiveness of the magnesium membrane shield technique in conjunction with bone grafting for ARP, assessing both clinical outcomes and histological bone regeneration.

METHODS

A 44-year-old female patient presented with a vertical fracture on tooth 24 (FDI Notation System) accompanied with complete destruction of the buccal bone wall. The treatment plan included tooth extraction, ARP using a combination of anorganic bovine bone and autologous bone grafting, and the application of a magnesium membrane as a shield to the pre-existing buccal wall. Six months post-procedure, a bone biopsy was taken from the implant site using a trephine bur.

RESULTS

Clinical and radiological evaluations six months after the procedure demonstrated sufficient bone volume for implant placement. Additionally, in the next three months, soft tissue conditioning with a provisional crown resulted in an aesthetically and functionally satisfactory outcome. Histological analysis of the bone biopsy revealed well-formed new bone in direct contact with residual biomaterial, with no signs of inflammation. Osteocytes were clearly visible within the newly formed bone matrix, indicating successful bone maturation. Active osteoblasts were observed along the bone-biomaterial interface, suggesting ongoing bone remodeling and integration. Additionally, histomorphometric evaluation revealed 47% newly formed bone, 32% soft tissue, and 19% residual biomaterial.

CONCLUSIONS

This case demonstrates the potential of the magnesium shield technique as an ARP technique in cases with severe buccal wall dehiscence. The technique yielded satisfactory clinical outcomes and promoted successful bone regeneration, as confirmed by histological analysis.

Socket Preservation Using Dense Polytetrafluoroethylene Membranes and Platelet-Rich Plasma

Socket preservation (SP) is a method aimed at reducing the post-extraction resorption of the alveolar crest and promoting bone deposition in the socket. It involves procedures such as atraumatic tooth extraction, guided regeneration with barrier membranes and bone substitutes, socket sealing, and immediate implant placement. This research aims to evaluate the influence of the combination of dense polytetrafluoroethylene (d-PTFE) membranes and platelet-rich plasma (PRP) on the vertical post-extraction resorption at the premolar and molar sites. Forty participants, aged 18-65 years, who needed extraction of a premolar or molar were enrolled and randomly assigned to an experimental group (SP with d-PTFE membrane and PRP) or a control group (spontaneous socket healing). The results demonstrated that SP with non-porous PTFE membranes and PRP reduced vertical bone resorption at the premolar and molar sites. Data analysis suggested that the buccal plate width influences the amount of its vertical resorption, but not as much as the management of the post-extraction socket (SP versus spontaneous socket healing). Further longitudinal randomized controlled trials are necessary to clarify which factors influence post-extraction ridge resorption and evaluate the success of different SP techniques.

Effect of radiation cross-linked collagen scaffold in alveolar ridge preservation of extraction socket

This study aimed to evaluate the properties of radiation cross-linked collagen scaffold (RCS) and its efficacy for alveolar ridge preservation (ARP). RCS was prepared from collagen dispersion by electron beam irradiation and freeze-drying. The microstructure, swelling ratio, area alteration and mechanical properties of RCS were characterized. Fifty-four New Zealand rabbits performing incisor extraction on maxilla and mandible were randomly assigned into positive, sham operation or treatment groups. Micro-computed tomography (micro-CT) scans, performed after 1, 4, and 12 weeks of surgery, were to assess changes in ridge height at buccal and palatal side, in ridge width and in micromorphological parameters. Histological analysis accessed socket microarchitecture. The results showed that RCS had stable mechanical properties and morphologic features that provided a reliable physical support for ARP. Dimensional changes in treatment group revealed significantly greater vertical height at buccal (5.32 [3.37, 7.26] mm, p < .0001) and palatal (4.37 [2.66, 6.09] mm, p < .0001) side, and horizontal width at the maxilla (0.16 [0.04, 0.28] mm, p < .01) and mandible (0.33 [0.11, 0.54] mm, p < .01) than those in sham operation group after 12 weeks. The treatment group had advantage than positive group in vertical height preservation, quantitatively. The order and density of bone trabeculae were improved in treatment group. These findings indicated that RCS had the potential to serve as an effective scaffold for ARP.

The Role of Bovine Amniotic Membrane and Hydroxyapatite for the Ridge Preservation

Ridge preservation is an important technique for maintaining the dimensions of the alveolar bone following tooth extraction, which is crucial for successful tooth rehabilitation. The combination of bovine amniotic membrane and hydroxyapatite has shown promise as a scaffold material containing growth factors that can stimulate osteogenic-related factors such as bone morphogenetic protein 2 (BMP2), Runt-related transcription factor 2 (RUNX2), and osteocalcin. This stimulation leads to collagen production and osteoblast proliferation, resulting in new bone formation. In this study, bovine amniotic membrane-hydroxyapatite (BAM-HA) composites were prepared using three different ratios of bovine amniotic membrane and hydroxyapatite (2 : 3, 3 : 7, 7 : 13). Thirty Sprague-Dawley rats had their first incisors extracted, and different types of BAM-HA were applied for ridge preservation. The control group received no treatment, while the positive control group was given xenograft. After 14 and 28 days, the animals were sacrificed, and immunohistochemical analysis was performed to evaluate the expression of BMP2, RUNX2, and osteocalcin. Additionally, a histological examination was conducted to analyse collagen thickness and osteoblast cell proliferation. The results demonstrated that the application of BAM-HA significantly increased collagen density, osteoblast cell proliferation, and the expression of BMP2, RUNX2, and osteoclacin compared to the control group (p < 0.05) on both days 14 and 28. Furthermore, increasing the hydroxyapatite content in the composite was found to enhance collagen thickness, osteoblast cell proliferation, and the expression of osteogenic-related factors. These preliminary findings suggest that the combination of BAM-HA can be used for ridge preservation to prevent further bone resorption following tooth extraction.

Evaluation and comparison of autologous particulate dentin with demineralized freeze dried bone allograft in ridge preservation procedures - a prospective clinical study

OBJECTIVES

To compare effectiveness of Autologous Particulate Dentin (APD) with Demineralized Freeze-Dried Bone Allograft (DFDBA) in ridge preservation, using radiographic and clinical parameters.

MATERIALS AND METHODS

Thirty subjects with indication of mandibular posterior teeth extraction were randomly assigned to either test or control group. After atraumatic extraction, ridge preservation was performed using APD or DFDBA mixed with i-PRF in test and control groups respectively. Both groups had sockets sealed with A-PRF membrane. Clinical parameters (plaque, gingival and healing indices) and radiographic parameters (vertical ridge height, horizontal ridge width) were assessed at baseline and 6 months using CBCT. Statistical analysis was performed using an independent t-test to compare clinical and radiographic parameters between the groups.

RESULTS

Both groups had significant decreases in ridge dimensions over 6 months (p < 0.001). The test group showed less reduction in ridge dimensions than control group at 6 months (p < 0.001). Mean change in vertical height was not significant (1.37 ± 1.32, 1.7311 ± 0.563), but in horizontal ridge width (1.3120 ± 1.13, 1.8093 ± 1.16) was significantly different between test and control groups respectively. There was no statistical difference in clinical parameters between the groups at 6 months (p > 0.001).

CONCLUSIONS

APD grafts resulted in significant improvements in radiographic parameters, specifically in vertical ridge height and horizontal ridge width, compared to DFDBA group.

CLINICAL RELEVANCE

Autologous particulate dentin is a promising, versatile substitute for regenerative procedures. While more research on its long-term efficacy and application is needed, current evidence suggests it could significantly improve patient care and outcomes.

Comparative Effectiveness of an Autologous Dentin Matrix for Alveolar Ridge Preservation

An urgent issue is the preservation or reconstruction of the volume of bone tissue in planning and surgical treatment in the fields of medicine, such as traumatology, orthopedics, maxillofacial surgery and dentistry. After tooth extraction, resorption of the bone tissue of the alveolar crest of the jaws occurs, which must either be further eliminated by performing additional operations or using osteoplastic material for socket preservation at the extraction stage. Background and Objectives: The aim of the study was a comparative analysis of various osteoplastic materials used to preserve the volume of bone tissue in the preimplantation period. Materials and Methods: As part of the study, 80 patients were treated, who underwent socket preservation using xenografts, plasma enriched with growth factors, an autologous dentin matrix (ADM) and hydroxyapatite. Results: The results of the treatment 16 weeks after removal were comprehensively analyzed using a morphometric analysis of the bone's volume, cone beam tomography and morphological examination of burr biopsy specimens, as well as by determining the stability of the installed implant at different stages of treatment. Conclusions: The lowest level of bone tissue resorption according to the CBCT data was noted in the ADM and xenograft groups. It should be noted that the use of osteoplastic material in jaw surgery when reconstructing alveolar defects is an essential procedure for preventing the atrophy of bone tissue.

Multidisciplinary management of implant failure: A case report

Key Clinical Message

This case report presents the interest of multidisciplinary management of extreme peri-implantitis requiring removal of implant emphasizing the different surgical and showing that the ovate pontic of conventional bridge is an optimal alternative for rehabilitation of the premolar sector, despite the fact that its main diffusion has been in the anterior sector due to the high demand aesthetic.

Abstract

Peri-implantitis leads to gradual peri-implant bone loss. Severe and extreme cases lead to complete implant failure and imply lost implants have to be removed. Residual ridge deformity management after implant removal is one of the factors contributing to improved aesthetic and functional results. Various grafting procedures have been developed to achieve this goal. This report describes a case of implant removal from the upper right first premolar due to advanced peri-implantitis in a 51-year-old female patient. Guided bone regeneration with a alloplastic bone graft and resorbable collagen membrane combined with roll pedicle connective tissue graftt was used for both socket and soft-tissue augmentation. This was combined with ovate design conventional provisional bridge. After a 6-month of healing phase, a perfect adaptation of the marginal gingiva around the provisional restoration was obtained. Cone beam computed tomography revealed significant bone fill and buccolingual dimensional stability. A conventional all-ceramic bridge with an oval pontic design was chosen as a definitive prosthetic solution to compensate for edentulism and maintain the good aesthetic results. According to the encouraging result obtained in this clinical case, the conventional prosthetic restoration associated with surgical reconstruction of failing tissues can be considered as a successful treatment in the case of advanced peri-implantitis requiring implant removal.

Use of autologous tooth-derived material as a graft in the post-extraction socket. Split-mouth study with radiological and histological analysis

BACKGROUND

The healing process after tooth removal involves bone remodelling which implies some loss of alveolar bone volume. Among materials proposed for minimising this remodelling and preserving the bone, autologous dental tissue is a promising option, but more data are needed. In this context, we evaluated size and density changes using cone beam computed tomography in autologous dental material (ADM)-preserved sockets compared to controls, and assessed biological responses by histological analysis.

METHODS

A split-mouth study was conducted including 22 patients, who underwent removal of ≥ 2 single-rooted teeth with intact sockets, assigning one socket to the experimental group which received ADM for alveolar preservation and another to the control group, which only underwent blood clot stabilisation. Cone beam computed tomography was performed postoperatively (week 0) and at weeks 8 and 16 to assess socket size and bone density. Histological analysis was carried out on trephine biopsies taken (Ø4 × 4.5 mm) from the experimental group.

RESULTS

Less horizontal shrinkage was observed in the ADM group, especially at week 16 considering the group-by-time interaction for the following variables: difference in height between the lingual and buccal alveolar crests (-1.00; p < .01; 95% CI: -0.28 - -1.73), and half-widths, measured as the distance from the long axis of the missing tooth to the buccal alveolar crest at 1 mm (-0.61; p < .01; 95% CI: -0.18 - -1.04) and at 3 mm (-0.56; p < .01; 95% CI: -0.15 - -0.97) below the crest, with mean decreases of 1.07 and 2.14 mm in height difference, 0.66 and 1.32 mm in half-width at 1 mm and 0.43 and 1.02 mm in half-width at 3 mm in ADM and control groups respectively. Densitometry analysis showed higher bone densities in Hounsfield units in the ADM group considering all factors analysed regardless of time point and socket third (coronal, middle, or apical). Histologically, there were no signs of inflammation or foreign body reaction, and dentin particles were surrounded by and in close contact with bone tissue.

CONCLUSION

These results add to the evidence that dentin can be used successfully as a material for alveolar socket preservation, given its desirable mechanical and biological properties, and warrant larger studies.

An injectable and coagulation-independent Tetra-PEG hydrogel bioadhesive for post-extraction hemostasis and alveolar bone regeneration

Effective control of post-extraction hemorrhage and alveolar bone resorption is critical for successful extraction socket treatment, which remains an unmet clinical challenge. Herein, an injectable Tetra-PEG hydrogel that possesses rapid gelation, firm tissue adhesion, high mechanical strength, suitable degradability, and excellent biocompatibility is developed as a sutureless and coagulation-independent bioadhesive for the management of extraction sockets. Our results demonstrate that the rapid and robust adhesive sealing of the extraction socket by the Tetra-PEG hydrogel can provide reliable protection for the underlying wound and stabilize blood clots to facilitate tissue healing. In vivo experiments using an anticoagulated rat tooth extraction model show that the hydrogel significantly outperformed clinically used cotton and gelatin sponge in hemostatic efficacy, wound closure, alveolar ridge preservation, and in situ alveolar bone regeneration. Histomorphological evaluations reveal the mechanisms for accelerated bone repair through suppressed long-term inflammation, elevated collagen deposition, higher osteoblast activity, and enhanced angiogenesis. Together, our study highlights the clinical potential of the developed injectable Tetra-PEG hydrogel for treating anticoagulant-related post-extraction hemorrhage and improving socket healing.

A Biodegradable Tissue Adhesive for Post-Extraction Alveolar Bone Regeneration under Ongoing Anticoagulation-A Microstructural Volumetric Analysis in a Rodent Model

In addition to post-extraction bleeding, pronounced alveolar bone resorption is a very common complication after tooth extraction in patients undergoing anticoagulation therapy. The novel, biodegenerative, polyurethane adhesive VIVO has shown a positive effect on soft tissue regeneration and hemostasis. However, the regenerative potential of VIVO in terms of bone regeneration has not yet been explored. The present rodent study compared the post-extraction bone healing of a collagen sponge (COSP) and VIVO in the context of ongoing anticoagulation therapy. According to a split-mouth design, a total of 178 extraction sockets were generated under rivaroxaban treatment, of which 89 extraction sockets were treated with VIVO and 89 with COSP. Post-extraction bone analysis was conducted via in vivo micro-computed tomography (µCT), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) after 5, 10, and 90 days. During the observation time of 90 days, µCT analysis revealed that VIVO and COSP led to significant increases in both bone volume and bone density (p ≤ 0.001). SEM images of the extraction sockets treated with either VIVO or COSP showed bone regeneration in the form of lamellar bone mass. Ratios of Ca/C and Ca/P observed via EDX indicated newly formed bone matrixes in both treatments after 90 days. There were no statistical differences between treatment with VIVO or COSP. The hemostatic agents VIVO and COSP were both able to prevent pronounced bone loss, and both demonstrated a strong positive influence on the bone regeneration of the alveolar ridge post-extraction.

Alveolar ridge preservation in rat tooth extraction model by chitosan-derived epigenetic modulation scaffold

PURPOSE

Alveolar ridge preservation is a surgical technique used to prevent dimensional changes in the alveolar bone by dressing biomaterials in the extraction socket. Recently, a chitosan biphasic calcium phosphate loaded with trichostatin A (CS/BCP/TSA) scaffold was introduced as an excellent bone-regeneration material. This study aimed to explore the biological properties of released trichostatin A (TSA) and evaluate the potential of the CS/BCP/TSA scaffold in preserving the alveolar ridge in a rat tooth extraction model.

METHODS

In vitro biocompatibility, histone deacetylase (HDAC) activity, and osteogenic differentiation of MC3T3-E1 cells were tested. For in vivo studies, the maxillary first molars (M1) of Wistar rats were extracted, and alveolar ridge preservation was performed using a CS/BCP/TSA scaffold or commercial bone graft. Micro-Computed Tomography (micro-CT), polyfluorochrome labeling, and histological analysis were used to evaluate the ridge-preservation ability.

RESULTS

The released TSA was cytocompatible. Inhibition of histone deacetylase (HDAC) activity and induction of osteogenic differentiation in MC3T3-E1 cells were confirmed. The socket dressing with the CS/BCP/TSA scaffold showed increased socket bone fill and preserved the buccal and middle aspects of the alveolar ridge compared with the conventional graft. Further analysis of the bone regeneration ability by histomorphometric and histological analyses demonstrated that CS/BCP/TSA showed a significantly higher potential to induce bone formation and complete healing in the extraction socket than the other groups.

CONCLUSIONS

The CS/BCP/TSA scaffold is a novel candidate for alveolar ridge preservation.

Finite Element Analysis and Fatigue Test of INTEGRA Dental Implant System

The study involved numerical FEA (finite element analysis) of dental implants. Based on this, fatigue tests were conducted according to the PN-EN 14801 standard required for the certification of dental products. Thanks to the research methodology developed by the authors, it was possible to conduct a thorough analysis of the impact of external and internal factors such as material, geometry, loading, and assembly of the dental system on the achieved value of fatigue strength limit in the examined object. For this purpose, FEM studies were based on identifying potential sites of fatigue crack initiation in reference to the results of the test conducted on a real model. The actions described in the study helped in the final evaluation of the dental system design process named by the manufacturer as INTEGRA OPTIMA 3.35. The objective of the research was to identify potential sites for fatigue crack initiation in a selected dental system built on the INTEGRA OPTIMA 3.35 set. The material used in the research was titanium grade 4. A map of reduced von Mises stresses was used to search for potential fatigue crack areas. The research [loading] was conducted on two mutually perpendicular planes positioned in such a way that the edge intersecting the planes coincided with the axis of the system. The research indicated that the connecting screw showed the least sensitivity (stress change) to the change in the loading plane, while the value of preload has a significant impact on the achieved fatigue strength of the system. In contrast, the endosteal implant (root) and the prosthetic connector showed the greatest sensitivity to the change in the loading plane. The method of mounting [securing] the endosteal implant using a holder, despite meeting the standards, may contribute to generating excessive stress concentration in the threaded part. Observation of the prosthetic connector in the Optima 3.35 system, cyclically loaded with a force of F ≈ 300 N in the area of the upper hexagonal peg, revealed a fatigue fracture. The observed change in stress peak in the dental connector for two different force application surfaces shows that the positioning of the dental system (setting of the socket in relation to the force action plane) is significantly decisive in estimating the limited fatigue strength.

Platelet-rich fibrin for rehydration and pre-vascularization of an acellular, collagen membrane of porcine origin

OBJECTIVES

Pre-vascularization of the collagen membranes with autologous platelet concentrates is a standard procedure in oral and maxillofacial surgery. This study analyzed the possible interaction of an acellular collagen membrane of porcine origin (NM) with platelet-rich fibrin (PRF) regarding its rehydration protocol with differences in pH values and effect on angiogenesis.

MATERIALS AND METHODS

NM was analyzed alone and combined with solid PRF by plotting or co-culturing with injectable PRF. Different media (venous blood, buffer solution with a fixed pH value of 7, saline solution, and injectable PRF) were used to analyze the influence on pH value during rehydration. Chorion allantois membrane assay (CAM) was applied to check pro-angiogenic effects after 24, 48, and 72 h, followed by immunohistochemical analysis.

RESULTS

Rehydration in injectable PRF showed acidity over time (p < 0.05). A definite pro-angiogenic effect of NM alone was found regarding neo-vessel formation supported by the respective light microscopically analysis without significant differences to PRF alone (p > 0.005). This pro-angiogenic effect could not be exaggerated when NM was combined with liquid/solid PRF (each p > 0.005).

CONCLUSIONS

Rehydration with liquid PRF of the collagen membrane results in acidity compared to a saline solution or patient's blood. The significant pro-angiogenic potential of the membrane alone resulted in enhanced neo-vessel formation that could not be optimized with the addition of PRF.

CLINICAL RELEVANCE STATEMENT

Using injectable PRF for rehydration protocol of the collagen membrane leads to acidosis that can ultimately optimize wound healing. Differences in the physio-mechanical interplay of collagen matrices and autologous platelet concentrates must result in clinical algorithms if pre-vascularization can maximize outcomes.

EFFECTS OF RECOMBINED HUMAN BONE MORPHOGENETIC PROTEIN-2 AS ALVEOLAR RIDGE PRESERVATION ON PAIN REDUCTION AND SOFT TISSUE HEALING PROCESS: A SPLIT MOUTH DESIGNED PILOT STUDY

Background: The alveolar ridge undergoes physiological bone resorption following tooth extraction. Several alveolar ridge preservation (ARP) techniques have been researched and developed in an effort to reduce this process and maintain a favorable volume and morphology of the alveolar ridge for appropriate implant placement. Bone morphogenetic proteins (BMPs) are proteins derived from a subgroup of the transforming growth factor  family that accelerates ossification by controlling essential factors of the bone induction cascade, resulting in the proliferation of osteoblasts from mesenchymal stem cells and the biosynthesis of bone matrices. One of these BMPs is recombinant human bone morphogenetic protein-2 (rhBMP-2) that has been authorized to be used for ARP. Objective: This study aims to evaluate the effect of rhBMP-2 on the healing process and the level of pain following dental extraction. Methods: In this split-mouth pilot study, 11 patients underwent extractions of a minimum of two teeth, and randomly, one of the alveolar sockets was filled with a hemostatic sponge while the other was filled with a hemostatic sponge embedded with rhBMP-2. Both sockets were sutured using the X technique. Wound healing measurements were done on days 3, 7, and 14, and each participant was requested to document his pain experience using the Numerical Rating Scale (NRS). Results: In accordance with clinical evidence, it was observed that the mean pain score was at its peak on day 0 and progressively diminished in the subsequent days. Notably, this decline was more pronounced in the rhBMP-2 group compared to the control group. Importantly, a statistically significant reduction in pain level was detected on day 3 within the rhBMP-2 group, in contrast to the control group (P-value < 0.05). This indicated that the application of rhBMP-2 led to a noteworthy and meaningful alleviation of pain on the third day after treatment, surpassing the impact observed in the control group. For the wound healing changes, it uncovered statistically significant mean differences across various time intervals: day 0 and day 3, day 0 and day 7, day 0 and day 14, day 3 and day 7, and day 7 and day 14 (P-value < 0.0001). These significant differences strongly suggest dynamic changes in wound closure rates over time. Furthermore, the observed differences were more pronounced in the rhBMP-2-treated group compared to the control group. This augmentation of differences indicates that the utilization of rhBMP-2 for ARP within a fresh socket site resulted in a heightened acceleration of the wound healing process. Conclusion: Our results suggest that rhBMP-2 can decrease post-operative pain after tooth extraction and accelerate the soft tissue healing process.

Alveolar Ridge Preservation with a Novel Cross-Linked Collagen Sponge: Histological Findings from a Case Report

Alveolar ridge preservation (ARP) is a well-documented procedure to maintain bone volume after tooth extraction in order to place implants. However, at the end of the healing process, the residual biomaterial that is not reabsorbed remains embedded in the bone over time. Ribose cross-linked biomaterials demonstrated their ability to promote osteoconduction and complete resorption. The aim of this study was to evaluate the histological healing pattern of a novel ribose cross-linked collagen sponge used as a grafting material left exposed in human sockets at the time of tooth extraction. On a single patient, non-restorable lower first molars were extracted on both sides, and a ribose cross-linked collagen sponge was placed bilaterally in the cavities and left uncovered at the end of the surgery. After six months, core biopsies were taken immediately prior to implant placement; after the sample preparation, a histological analysis was performed. The results are very promising for substitution with newly formed bone and the amount of residual material. Ribose cross-linked collagen sponge could represent a valid alternative to conventional biomaterials for ARP procedures with no need for flap advancement and/or the addition of a membrane to cover the graft, reducing the invasiveness, complexity, and costs of the treatment.

Socket Preservation and Guided Bone Regeneration: Prerequisites for Successful Implant Dentistry

Implant success is measured not only by implant survival but also by the long-term aesthetic and functional results. Implant placement should be prosthetically driven, with proper three-dimensional positioning for optimal support and stability of the tissues. Several procedures could be performed to ensure this requirement. While socket preservation (SP) is performed at the stage of tooth extraction, guided bone regeneration (GBR) takes place before or simultaneous to implant placement. The current review aims to summarize and discuss the procedures used for the preparation of the implant site, the preservation of the existing tissues, and their augmentation in cases of deficiency. An electronic search using Google Scholar, PubMed, and Scopus was conducted up to October 2023, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review summarizes the current knowledge on SP and GBR as prerequisites for future implant placement. Their indications, advantages, and limitations have been thoroughly evaluated and some recommendations for further research have been suggested. Implant placement in sites with severe bone resorption is extremely challenging. It necessitates the application of different surgical techniques, especially augmentation procedures, including guided bone regeneration. The need for such procedures could be avoided or at least minimized by the execution of SP after tooth extraction or immediate/early implant placement.

Use of Injectable Platelet-Rich Fibrin Accompanied by Bone Graft in Socket Endurance: A Radiographic and Histological Study

Background Ridge preservation became a crucial dental health issue and strategy to keep away from ridge defacement after post-tooth loss. The recent scientific evolution of platelet-rich fibrin (PRF) comprises a parenteral formulation of PRF. The combined allograft for socket preservation gives benefits. In this study, bone allografts, demineralized freeze-dried bone allografts (DFDBA) and freeze-dried bone allografts (FDBA) are used in a 30:70 ratio alone or in combination with injectable PRF (I-PRF) for socket preservation. Methods This study is a radiographic and histological examination conducted on 60 participants aged between 19-65 years. Participating patients agreed voluntarily that they would not bear any fixed prosthesis for the next nine months and plan for implanted teeth placement, including multi-rooted mandibular molars denticles. Both groups received atraumatic extraction; then, the socket was preserved with bone allograft alone in the control group and bone allograft mixed with I-PRF, forming sticky bone, in the experimental group. Clinical, radiological, and histological assessments were taken at the inception stage, three months, six months, and nine months. A multivariate regression model and a generalized estimating equation (GEE) model were used to analyse the effects of these changes on outcomes. Results In all the parameters, the test group indicated a good amount of bone growth with increasing intervals of time for bone height radiographically with statistically significant difference present (p<0.05) and histologically after nine months when socket site grafted with bone graft in combination with I-PRF. Conclusion This study's results demonstrated that I-PRF possesses the potential to regenerate and heal in the tooth-extracted socket. This study further recommends the implementation of I-PRF in safeguarding and conserving the raised rim of the tooth. Future research should take place on the osteogenic capability of I-PRF in more comprehensive ridge accession surgical procedures and additional expanding and improving capacities in periodontal reconstruction.

The Use of Autogenous Teeth Tissues Grafts for Alveolar Bone Reconstruction: a Systematic Review

Objectives

Enough bone around the implant is an important factor in ensuring the stability and longevity of the implant. Therefore, alveolar bone regeneration procedures are often required. A relatively new bone substitute is made from autogenous teeth. There are more and more studies in the scientific literature that perform regenerative alveolar bone procedures using autogenous tissues substitutes made from extracted teeth. The objective of this systematic literature review is to systematize information and present conclusions about the effectiveness of this regenerative material.

Material and Methods

Scientific articles were selected using the PRISMA recommendations. Publications have been carried out since January 1, 2012 to January 1, 2022. The review includes articles in English, clinical studies in humans who underwent bone augmentation prior to or during dental implantation using an autogenous teeth tissues substitute.

Results

A total of 7 publications were included in this systematic literature review. Summarizing the data of the publications, 258 patients participated in the studies, 240 subjects were included in the results for various reasons, and a total of 298 implants were inserted. No statistically significant results were found in the five studies. Two studies comparing autogenous tooth graft with xenogeneic bone graft and autogenous teeth tissues showed statistically significant positive results in autogenous tooth group.

Conclusions

Within the limitations of this study, autogenous tissues graft derived from teeth are an effective material and can be used as an alternative to other bone grafts existing on the market. Further studies with a longer follow-up period are needed to validate these findings.

Regeneration of Buccal Wall Defects after Tooth Extraction with Biphasic Calcium Phosphate in Injectable Form vs. Bovine Xenograft: A Randomized Controlled Clinical Trial

Bone healing after tooth extraction may be affected by defects of the alveolus buccal wall, such as fenestrations and dehiscences. Therefore, to minimize dimensional changes it is advisable to perform alveolar ridge preservation after tooth extractions. Different biomaterials are used for this purpose. The aim of this study was to investigate the qualitative and quantitative histological changes in human biopsies taken after 6 months of healing of extraction sockets with buccal wall defects. For this purpose, the defects of 36 patients (18 per group) were treated with injectable biphasic calcium phosphate (I-BCP) or bovine xenograft (BX) after extraction. After six months of healing, biopsies were taken and proceeded to the histology laboratory. No evidence of an inflammatory response of the tissue was observed in the biopsies of either group, and the newly formed bone (NB) was in close contact with the remaining biomaterial (BM). The histomorphometric results showed that there was no statistically significant difference between the groups in the mean percentage of NB (p = 0.854), BM (p = 0.129), and soft tissue (p = 0.094). To conclude, both biomaterials exhibited osteoconductivity and biocompatibility and achieved satisfactory bone regeneration of buccal wall defects after tooth extraction.

Clinical and radiographic assessment of cross-linked hyaluronic acid addition in demineralized bovine bone based alveolar ridge preservation: A human randomized split-mouth pilot study

PURPOSE

To investigate clinically and radiographically at 4 months post-operatively the outcomes of mixing demineralized bovine bone material (DBBM) with cross-linked hyaluronic acid in alveolar ridge preservation.

MATERIAL AND METHODS

Seven patients presenting bilateral hopeless teeth (14 teeth) were enrolled in the study, the test site contained demineralized bovine bone material (DBBM) mixed with cross-linked hyaluronic acid (xHyA) while the control site contained only DBBM. 4 months post-operatively prior to implant placement a Cone beam computed tomography (CBCT) scan was recorded and compared to the initial scan to assess the volumetric and linear bone resorption that occurred in both sites. Clinically, sites that needed further bone grafting at the implant placement stage were recorded. Differences in volumetric and linear bone resorption between both groups were assessed using Wilcoxon signed rank test. McNemar test was also used to evaluate difference in bone grafting need between both groups.

RESULTS

All sites healed uneventfully, volumetric and linear resorption differences between the baseline and 4 months post-operatively were obtained for each site. The mean volumetric and linear bone resorption were respectively 36.56 ± 1.69%, 1.42 ± 0.16 mm in the controls sites and 26.96 ± 1.83%; 0.73 ± 0.052 mm in the tests sites. The values were significantly higher among controls sites (P=0.018). No significant differences were observed in the need for bone grafting between both groups.

CONCLUSION

Cross-linked hyaluronic acid (xHyA) appears to limit the post-extractional alveolar bone resorption when mixed with DBBM.

Hybrid Resorbable 3D-Printed Mesh/Electrospun Nanofibrous Drug/Biomolecule-Eluting Mats for Alveolar Ridge Preservation

In this research study, we developed hybrid resorbable three-dimensional (3D)-printed mesh/electrospun nanofibrous biomolecule-eluting mats for alveolar ridge preservation. The fabrication process involved the use of 3D printing and coaxial electrospinning technologies. Specifically, we utilized a lab-developed solution-extrusion 3D printer to fabricate polycaprolactone (PCL) meshes. Then, bi-layered poly(lactic-co-glycolic acid) (PLGA) nanofibrous membranes, which embedded ibuprofen and epidermal growth factor (EGF), were prepared utilizing electrospinning and coaxial electrospinning techniques, respectively. To ensure the quality of the produced mesh and spun nanofibers, we carried out a characterization process. Furthermore, we estimated the in vitro and in vivo release characteristics of ibuprofen and EGF, respectively, using high-performance liquid chromatography and enzyme-linked immunosorbent assays. In addition, we assessed the effectiveness of hybrid nanofibrous mats for preserving the alveolar ridge by adopting an animal model and conducting a histology examination. The study findings demonstrate that the nanofibrous mats provided a continuous discharge of ibuprofen and EGF for more than four weeks. Moreover, the animal test carried out in vivo showed that animals implanted with this combination of mesh and drug-eluting mats displayed considerably greater mobility than those without mats. The histological analysis revealed no unfavorable impacts from the drug-eluting mats. Our study demonstrated the successful fabrication of resorbable drug-eluting nanofibrous mats for alveolar ridge preservation by utilizing both 3D printing and coaxial electrospinning technologies.

Extraction Socket Augmentation with Autologous Platelet-Rich Fibrin (PRF): The Rationale for Socket Augmentation

After tooth extraction, the alveolar ridge undergoes a physiological process of remodelling and disuse atrophy. Socket augmentation (SA) has been shown to preserve alveolar bone volume in order to facilitate implant placement and reduce the need for staged grafting at a later date. Although autogenic grafting has been shown to be the gold standard in bone regeneration, it has significant disadvantages. To prevent post-extraction volumetric alterations and alveolar bone resorption occurring, alternative grafting materials, including xenografts, alloplasts, and allografts, have been used successfully in fresh extraction sites. However, these materials act mostly as bio-scaffolds and require a slower integration period of 6-8 months prior to implant placement. Recently, the use of autologous platelet-rich fibrin (PRF) has been advocated alongside socket augmentation as a method of bio-enhancement of healing of soft and hard tissues. PRF contains platelet-derived growth factors, hormones, and bioactive components such as cytokines that have been shown to promote angiogenesis and tissue regeneration during wound healing. The aim of this article is to review the evidence base for the SA technique Clinical benefits of SA will be discussed with a reference to two cases. Therefore, this narrative review will discuss the post-extraction bone changes, the importance of SA, and the bio-enhancement role of PRF in the management of extraction site defects when the alternative technique of immediate implant placement is not possible or contraindicated.

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.

Osteogenic Potential of Autologous Dentin Graft Compared with Bovine Xenograft Mixed with Autologous Bone in the Esthetic Zone: Radiographic, Histologic and Immunohistochemical Evaluation

This prospective, randomized, controlled clinical trial reports clinical, radiographic, histologic and immunohistochemical results of autologous dentin graft (ADG) and its comparison with a mixture of bovine xenograft with autologous bone (BX+AB). After tooth extraction in the esthetic zone of maxilla, the alveolar ridge of 20 patients in the test group was augmented with ADG, while 17 patients in the control group received the combination of BX+AB. Cone beam computed tomography (CBCT) was performed before tooth extraction and after 4 months when a total of 22 bone biopsies were harvested and subjected to histological and immunohistochemical analysis. Radiological analysis showed comparable results of bone dimension loss in both groups. Quantitative histologic analysis showed comparable results with no statistically significant differences between the groups. Immunohistochemical staining with TNF-α and BMP-4 antibodies revealed immunopositivity in both groups. A statistically significant difference between the groups was found in the intensity of TNF-α in the area of newly formed bone (p = 0.0003) and around remaining biomaterial particles (p = 0.0027), and in the intensity of BMP-4 in the area around biomaterial particles (p = 0.0001). Overall, ADG showed biocompatibility and achieved successful bone regeneration in the esthetic zone of the maxilla similar to BX+AB.

Tomographic Evaluation of Alveolar Ridge Preservation Using Bone Substitutes and Collagen Membranes—A Retrospective Pilot Study

Alveolar ridge preservation (ARP) reduces dimensional changes following tooth extraction. We evaluated the changes in alveolar ridge dimensions after ARP using bone substitutes and collagen membranes. Objectives included the tomographic evaluation of sites prior to extraction and six months after ARP and the assessment of the extent ARP preserved the ridge and reduced the need for additional augmentation at the time of implant placement. A total of 12 participants who underwent ARP in the Postgraduate Periodontics Clinic (Faculty of Dentistry) were included. Cone beam computed tomography images were used to retrospectively assess 17 sites prior to and six months after dental extraction. Alveolar ridge changes were recorded and analysed using reproducible reference points. The alveolar ridge height was measured at buccal and palatal/lingual aspects, whilst width was measured at crestal level, 2 mm, 4 mm and 6 mm below the crest. Statistically significant changes were found in alveolar ridge width at all four heights, with mean reduction differences ranging from 1.16 mm to 2.84 mm. Likewise, significant changes in the palatal/lingual alveolar ridge height (1.28 mm) were observed. However, changes of 0.79 mm in buccal alveolar ridge height were not significant (p = 0.077). Although ARP reduced dimensional changes following a tooth extraction, some degree of alveolar ridge collapse could not be avoided. The amount of resorption on the buccal aspect of the ridge was less compared to the palatal/lingual after ARP. This indicated that the use of bone substitutes and collagen membranes was effective in reducing changes in the buccal alveolar ridge height.

Can Our Blood Help Ensure Antimicrobial and Anti-Inflammatory Properties in Oral and Maxillofacial Surgery?

In recent decades, the potential of PRF has been extensively studied. The number of studies about PRF has increased three times since the year 2012, but the full spectrum of its fundamental properties, such as antimicrobial and anti-inflammatory activity, is not clearly described. In oral and maxillofacial surgery, PRF is described in alveolar ridge preservation, orthognathic surgery, cleft lip and palate surgery, maxillary sinus augmentation, and dental implant placement as demonstrating favorable results and its clinical advantages. The structural complexity, inhomogeneous nature, and clotting ability of PRF make its antimicrobial effect evaluation complicated. Nevertheless, most of the used antimicrobial testing methods are based on antibacterial agent diffusion ability in culture media. Because the oral and maxillofacial region is the most frequent area of PRF application, its antimicrobial activity evaluation also prevails in the oral microbiome. PRF's biological potential is highly dependent on the specific preparation protocol and methodology used; it should be carefully prepared and kept under proper conditions to keep cellular content alive. PRF's influence on living cells demonstrates a stimulating effect on bone regeneration, and an angiogenetic effect, and it provides anti-inflammatory activity. According to analyzed studies, PRF demonstrated success in oral and maxillofacial surgery in various methods of application. Antibacterial and anti-inflammatory properties were proven by antibacterial activity against different bacterial species, sustained growth factor, sustained release, and cell activity on the material application. Accurately and correctly prepared PRF can ensure antibacterial and anti-inflammatory properties, and it can be a beneficial clinical tool in oral and maxillofacial surgery.

Characterization of bioactive substances involved in the induction of bone augmentation using demineralized bone sheets

PURPOSE

To investigate the bone augmentation ability of demineralized bone sheets mixed with allogeneic bone with protein fractions containing bioactive substances and the interaction between coexisting bioactive substances and proteins.

METHODS

Four types of demineralized bone sheets mixed with allogeneic bone in the presence or absence of bone proteins were created. Transplantation experiments using each demineralized bone sheet were performed in rats, and their ability to induce bone augmentation was analysed by microcomputed tomography images. Bioactive substances in bone proteins were isolated by heparin affinity chromatography and detected by the measurement of alkaline phosphatase activity in human periodontal ligament cells and dual luciferase assays. Noncollagenous proteins (NCPs) coexisting with the bioactive substances were identified by mass spectrometry, and their interaction with bioactive substances was investigated by in vitro binding experiments.

RESULTS

Demineralized bone sheets containing bone proteins possessed the ability to induce bone augmentation. Bone proteins were isolated into five fractions by heparin affinity chromatography, and transforming growth factor-beta (TGF-β) was detected in the third fraction (Hep-c). Dentin matrix protein 1 (DMP1), matrix extracellular phosphoglycoprotein (MEPE), and biglycan (BGN) also coexisted in Hep-c, and the binding of these proteins to TGF-β increased TGF-β activity by approximately 14.7% to 32.7%.

CONCLUSIONS

Demineralized bone sheets are capable of inducing bone augmentation, and this ability is mainly due to TGF-β in the bone protein mixed with the sheets. The activity of TGF-β is maintained when binding to bone NCPs such as DMP1, MEPE, and BGN in the sheets.

A comparison between anorganic bone and collagen-preserving bone xenografts for alveolar ridge preservation: systematic review and future perspectives

After tooth extraction, dimensional changes affect the alveolar socket, leading to loss in alveolar bone height and width. Histological modifications also occur, with initial formation of a blood clot that is replaced with granulation tissue and subsequently with a provisional connective tissue matrix. Spontaneous healing ends with socket filling with woven bone, which is gradually replaced with lamellar bone and bone marrow. Adequate alveolar ridge dimensions and bone quality are required to assure optimal stability and osseointegration following dental implant placement. When a tooth is extracted, alveolar ridge preservation (ARP) procedures are an effective method to prevent collapse of the post-extraction socket. Heterologous bone is widely chosen by clinicians for ARP, and anorganic bone xenografts (ABXs) made bioinert by heat treatment represents the most used biomaterial in clinical applications. Collagen-preserving bone xenografts (CBXs) made of porcine or equine bone are fabricated by less invasive chemical or enzymatic treatments to remove xenogenic antigens, and these are also effective in preserving post-extraction sites. Clinical differences between anorganic bone substitutes and collagen-preserving materials are not well documented in the literature but understanding these differences could clarify how processing protocols influence biomaterial behavior in situ. This systematic review of the literature compares the dimensional changes and histological features of ABXs versus CBXs in ridge preservation procedures to promote awareness of different bone xenograft efficacies in stimulating the healing of post-extraction sockets.

Demineralized human dentin matrix for alveolar ridge preservation using a volumetric and histologic analyses in rats

The aim of this study was to evaluate a Demineralized Human Dentine Matrix (DHDM) as viable biomaterial for alveolar ridge preservation in a rat model. Wistar rats were submitted to the extraction of maxillary first molars bilaterally. Sockets were filled with biomaterials and divided into 4 experimental groups (n=5): blood clot, autogenous bone, bovine-derived xenograft (BDX) and DHDM. Animals were sacrificed at 7, 14 e 28 days. Microtomography (uCT) volumetric evaluation and qualitative histological analyses were performed. Results obtained through the uCT showed similar values between the DHDM and the other experimental groups. The histological evaluation demonstrated DHDM with an unspecific inflammatory process and bone neoformation with slow reabsorption of the material. This result indicates that DHDM implanted in rat sockets is biocompatible and reduces the alveolar ridge volume loss after tooth extraction.

Alveolar Bone Remodeling with or without Collagen Filling of the Extraction Socket: A High-Resolution X-ray Tomography Animal Study

The healing process of the tooth extraction socket often leads to significant resorption of the alveolar bone, eventually causing clinical difficulties for future implant-supported rehabilitations. The aim of the present animal study was to evaluate alveolar bone remodeling after tooth extraction in a rabbit model, either with or without the use of a plain collagen plug inside the socket, by means of micro-computed tomography. The study included the micro-tomography analysis of 36 rabbits’ incisor extraction sockets, either left empty or filled with a collagen plug. All animals were euthanized in a staggered manner, in order to address molecular, histologic, and radiographic analyses at different time-points, up to 90 days after surgery. The three-dimensional evaluation was carried out using micro-computed tomography technology on excised bone blocks including the alveolus and the contralateral bone. Both linear and volumetric measures were recorded: the percentage of bone volume change (ΔBV) within the region of interest was considered the primary endpoint of the study. The micro-CT analysis revealed mean volumetric changes of −58.1% ± from baseline to 3 months for the control group, and almost no bone loss for the test group, −4.6%. The sockets treated with the collagen plug showed significantly less dimensional resorption, while the natural-healing group showed an evident collapse of the alveolar bone three months after extraction surgery.

Polyphosphate-crosslinked collagen scaffolds for hemostasis and alveolar bone regeneration after tooth extraction

Post-extraction bleeding and alveolar bone resorption are the two frequently encountered complications after tooth extraction that result in poor healing and rehabilitation difficulties. The present study covalently bonded polyphosphate onto a collagen scaffold (P-CS) by crosslinking. The P-CS demonstrated improved hemostatic property in a healthy rat model and an anticoagulant-treated rat model. This improvement is attributed to the increase in hydrophilicity, increased thrombin generation, platelet activation and stimulation of the intrinsic coagulation pathway. In addition, the P-CS promoted the in-situ bone regeneration and alveolar ridge preservation in a rat alveolar bone defect model. The promotion is attributed to enhanced osteogenic differentiation of bone marrow stromal cells. Osteogenesis was improved by both polyphosphate and blood clots. Taken together, P-CS possesses favorable hemostasis and alveolar ridge preservation capability. It may be used as an effective treatment option for post-extraction bleeding and alveolar bone loss.

Statement of significance

Collagen scaffold is commonly used for the treatment of post-extraction bleeding and alveolar bone loss after tooth extraction. However, its application is hampered by insufficient hemostatic and osteoinductive property. Crosslinking polyphosphate with collagen produces a modified collagen scaffold that possesses improved hemostatic performance and augmented bone regeneration potential.

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Polyphosphate-crosslinked collagen scaffold (P-CS) showed better hemostatic effect in healthy or anticoagulant-treated rats.

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The promoted bone regeneration ability of P-CS might also be related to the clot alteration caused by polyphosphate.

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P-CS has therapeutic potential in bleeding control and alveolar ridge preservation after tooth extraction.

A 15-year unique observational study of intraligamentary local anaesthesia for posterior mandibular extractions

Introduction Intraligamentary local anaesthesia (ILA) with articaine is described as an effective alternative to inferior alveolar nerve block (IANB) for extraction of posterior teeth in the mandible, with reduced risk of complications.Aim To investigate ILA with 4% articaine and conventional syringe as a unique method for providing tooth extractions in the posterior mandible.Materials and methods All consecutive teeth to be extracted in the posterior mandible were recruited to the study, within exclusion criteria, between 2002 and 2017 in one London NHS and private dental practice. Four percent articaine was given by ILA with a conventional syringe slowly at two points lingual and two points buccal adjacent to each tooth. Extraction procedures were all performed flapless. Heavily broken-down teeth (n = 43) were extracted by sectioning of roots, guttering and elevation with luxators using socket preservation techniques. Demographic, quantitative and qualitative data were collected at initial appointments and up to 15 years at review.Results The median age was 64 years (interquartile range 17). Teeth extracted included 272 mandibular molars and second premolars, due to periodontal disease (34%), irreversible pulpitis (29%) or posterior tooth fracture (27%). The majority of extractions were second molars (44%), followed by first molars (29%), second premolars (17%) and third molars (10%). Sufficient anaesthesia was achieved within five minutes for all extractions. Procedures lasted less than 30 minutes. Patient feedback reported that the extraction using ILA was quicker than expected and painless, with limited anaesthesia of tissues other than the teeth to be extracted. Numeric rating scale (NRS) scores for pain (0-10) were all less than 3. No complications were recorded.Conclusion The ILA anaesthetic technique is effective for the purpose of a broad range of posterior tooth extractions in the mandible and within certain clinical parameters. It mitigates risks, including nerve injury and cardiovascular disturbances, associated with repeated IANB. This is the largest study of its kind and is conducted in primary care.

Evaluation of Collagen Membranes Coated with Testosterone and Alendronate to Improve Guided Bone Regeneration in Mandibular Bone Defects in Minipigs

OBJECTIVES

The purpose of the present in vivo study was to evaluate whether pericard collagen membranes coated with ancillary amounts of testosterone and alendronate in a poly-lactic glycolic acid (PLGA) carrier as compared to uncoated membranes will improve early bone regeneration.

MATERIAL AND METHODS

In each of 16 minipigs, four standardized mandibular intraosseous defects were made bilaterally. The defects were filled with Bio-Oss^® granules and covered with a non-coated or coated membrane. Membranes were spray-coated with 4 layers of PLGA containing testosterone and alendronate resulting in 20, 50 or 125 μg/cm² of testosterone and 20 µg/cm² alendronate (F20, F50, F125). Non-coated membranes served as controls (F0). Animals were sacrificed at 6 and 12 weeks after treatment. Qualitative and quantitative histological evaluations of bone regeneration were performed. Differences between groups were assessed by paired Student's t-test.

RESULTS

Light microscopical analysis showed new bone formation that was in close contact with the Bio-Oss^® surface without an intervening non-mineralized tissue layer. Histomorphometric analysis of newly formed bone showed a significant 20% increase in area in the F125 coated membrane treated defects (40 [SD 10]%) compared to the F0 treated defects after 6 weeks (33 [SD 10]%, P = 0.013). At week 12, the total percentage of new bone was increased compared to week 6, but no increase in newly formed bone compared to F0 was observed.

CONCLUSIONS

The data from this in vivo study indicate that F125 collagen membranes coated with testosterone and alendronate resulted in superior bone formation (+24%) when normalized to control sites using uncoated membranes.

The Injectable Woven Bone-Like Hydrogel to Perform Alveolar Ridge Preservation With Adapted Remodeling Performance After Tooth Extraction

Grafting bone substitute is paramount to prevent the alveolar ridge resorption after tooth extraction and facilitate the subsequent implant treatment. An ideal bone substitute should acquire the excellent osteogenic property, more importantly, possess the suitable remodeling rate in balance with bone formation and desirable clinical manageability. However, none of bone substitute is simultaneously characterized by these features, and currently, the limited remodeling property leads to the excessive waiting time before implantation. Enlightened by woven bone, the transitional tissue that is able to induce osteogenesis during bone healing could be easily remodeled within a short period and depend on the favorable injectability of hydrogel, an injectable woven bone-like hydrogel (IWBLH) was constructed in this study to address the above problems. To mimic the component and hierarchical structure of woven bone, amorphous calcium phosphate (ACP) and mineralized collagen fibril were synthesized and compounded with alginate to form IWBLHs with various ratio. Screened by physiochemical characterization and in vitro biological assays, an optimal IWBLH was selected and further explored in rat model of tooth extraction. Compared with the most widely used bone substitute, we showed that IWBLH could be easily handled to fully fill the tooth socket, perform a comparable function to prevent the alveolar bone resorption, and completely remodeled within 4 weeks. This IWBLH stands as a promising candidate for alveolar ridge preservation (ARP) in future.