A comparison of ePTFE membranes alone or in combination with platelet-derived growth factors and insulin-like growth factor-I or demineralized freeze-dried bone in promoting bone formation around immediate extraction socket implants

Comparison of crestal bone loss and papilla fill after conventional and immediate implant placement: A 12 month clinical and radiographic prospective study

Background

The problem of missing teeth persists in all age groups. The main objective of implants in dentistry is to provide a restoration that reconstructs the shape and restores esthetics and functions of edentulous areas. The objectives of this study are to compare the crestal bone level changes and papillary fill after placement of implants in fresh extraction socket, i.e. immediate implant placement, and healed extraction socket, i.e. delayed or conventional implant placement, and to assess other clinical parameters such as modified plaque index (mPI), modified gingival index (mGI) and gingival biotype in between the groups and within the groups.

Methods

18 patients were recruited in the study out of which 9 patients received implants as per immediate implant placement protocol (group 1) and 9 patients received implants as per conventional implant placement protocol (group 2). All patients were evaluated for gingival biotype, mPI and mGI and papillary fill was assessed as per Jemt's papilla score as clinical parameters. Implant site was assessed for radiographic bone loss using Image J software. Statistical analysis was performed using independent t test, paired t test and chi square test.

Results

At the end of 1 year, results showed that crestal bone loss was seen more in the immediate group than the conventional group. Conventional implants showed better papillary fill than implants placed in fresh extraction sockets. Plaque scores were assessed as per modified plaque index, which showed better results in the conventional group. Modified gingival index was used to assess gingival status which showed better results in the immediate group one year later.

Conclusions

Findings from the study suggest that crestal bone loss was found to be increased in the immediate group than the conventional group and papillary fill was better in the conventional group than the immediate group.Registration: CTRI ( CTRI/2019/09/021340).

Applications of Gene Therapy in Dentistry: A Review Article

Gene therapy promises to possess a good prospect in bridging the gap between dental applications and medicine. The dynamic therapeutic modalities of gene therapy have been advancing rapidly. Conventional approaches are being revamped to be more comprehensive and pre-emptive, which could do away with the need for surgery and medicine altogether. The complementary base sequences known as genes convey the instructions required to manufacture proteins. The oral cavity is one of the most accessible locations for the therapeutic intervention of gene therapy for several oral tissues. In 1990, the first significant trial of gene therapy was overseen to alleviate adenosine deaminase deficiency. The notion of genetic engineering has become increasingly appealing as a reflection of its benefits over conventional treatment modalities. An example of how this technology may alter dentistry is the implementation of gene therapy for dental and oral ailments. The objective of this article is to examine the effects of gene therapy on the field of dentistry, periodontology and implantology. Furthermore, the therapeutic factors of disease therapy, minimal invasion, and appropriate outcome have indeed been taken into consideration.

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

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

Histological Evaluation of Guided Bone Regeneration in Osseous Defects Using A Novel Non-Resorbable Membrane

BACKGROUND: Guided bone regeneration and guided tissue regeneration procedures have been performed using barrier membranes in clinical dentistry to enhance bone formation in osseous defects, ridge preservation and reconstruction. Despite the considerable number of new biomaterials that develop with more advantages and fewer disadvantages for bone regeneration, the cost and surgical approach difficulties are still the main obstacles that we tried to overcome using the novel membrane. AIM: Our research aimed to assess histologically the bone formation using the novel membrane in experimental bone defects. MATERIAL AND METHODS: Our study was conducted on ten mongrel dogs. Each animal presented two groups. The first group was at the left side of the animal mandible which received Bio-Oss only while the right side received Bio-Oss and was covered by the novel non-resorbable membrane. These dogs were sacrificed (3, 6, 9 and 12 weeks) postoperatively for histological assessment of healing and bone formation of osseous defects. RESULTS: The histological evaluation showed that the formation of new bone in group I (Bio-OSS only) was less in amount as compared with group II (Bio-Oss with the novel non-resorbable membrane). CONCLUSION: The present clinical findings revealed that the novel non-resorbable membrane was inert and induced no inflammatory reaction or graft rejection. The study provided histological evidence of new bone formation in close contact with host bone due to osteoconductivity of Bio-Oss and cell occlussiveness of the membrane.

Effect of Platelet Concentrates on Marginal Bone Loss of Immediate Implant Procedures: A Systematic Review and Meta-Analysis

BACKGROUND

To evaluate marginal bone loss (MBL) in immediate implant procedures (IIP) placed in conjunction with platelet concentrates (PCs) compared to IIP without PCs.

METHODS

A search was performed in four databases. Clinical trials evaluating MBL of IIP placed with and without PCs were included. The random effects model was conducted for meta-analysis.

RESULTS

Eight clinical trials that evaluated MBL in millimeters were included. A total of 148 patients and 232 immediate implants were evaluated. The meta-analysis showed a statistically significant reduction on MBL of IIP placed with PCs when compared to the non-PCs group at 6 months (p < 0.00001) and 12 months (p < 0.00001) follow-ups. No statistically significant differences were observed on MBL of IIP when compared PCs + bone graft group vs. only bone grafting at 6 months (p = 0.51), and a significant higher MBL of IIP placed with PCs + bone graft when compared to only bone grafting at 12 months was found (p = 0.03).

CONCLUSIONS

MBL of IIP at 6 and 12 months follow-ups is lower when PCs are applied in comparison to not placing PCs, which may lead to more predictable implant treatments in the medium term. However, MBL seems not to diminish when PCs + bone graft are applied when compared to only bone grafting.

Immediate loading of fixed partial prostheses reconstructed using either tapered or straight implants in the posterior area: A randomized clinical trial

BACKGROUND

In immediately loaded implants within 72 h after the implant placement in the unilaterally and partially edentulous ridge, primary stability is considered critical, which can be influenced by the design of the implant fixture.

PURPOSE

To determine the outcomes at 1 year after the immediate loading of multiunit fixed partial prostheses over either tapered implants (TIs) or straight implants (SIs) in the posterior region.

MATERIALS AND METHODS

Forty-eight patients (24 patients, 52 implants in TI group; 24 patients, 50 implants in SI group) were included for the study. Except for the one SI group patient whose two implants showed the insertion torque less than 30 Ncm, provisional prostheses designed and fabricated from intraoral scan data obtained immediately after implant surgery were delivered to rest of the 47 subjects at 3-7 days. After a year, the survival rate was estimated by intention-to-treat (ITT) and per-protocol (PP) analyses, and marginal bone loss (MBL) and implant stability were also analyzed statistically (p < 0.05).

RESULTS

Survival rate at implant level in TI group was 96.2%, and that of SI group in the ITT analysis was 86.0%. Intergroup difference, however, was not statistically significant (p > 0.05). Insertion torque was significantly higher in TI group than SI group (47.12 ± 6.37 Ncm vs. 41.60 ± 9.77 Ncm; p < 0.05). MBLs of both groups were less than 0.1 mm at 1-year follow-up and was similar between two groups (p > 0.05).

CONCLUSIONS

Immediate loading of fixed partial prostheses after TI and SI placement showed reliable outcomes in the partially edentulous posterior ridge. In terms of the initial mechanical stability, the performance was superior for TIs than for SIs.

Evaluation of Guided Bone Regeneration in Critical Defects Using Bovine and Porcine Collagen Membranes: Histomorphometric and Immunohistochemical Analyses

Guided bone regeneration (GBR) is a technique used to facilitate bone regeneration, which uses a biocompatible membrane acting as a physical barrier to prevent the adjacent connective tissue from invading the bone defect. The aim of this study was to evaluate and compare the effectiveness of bovine and porcine collagenous membranes as barriers to connective tissue invasion during the repair of critical bone defects in rat calvaria, using histological, histometric, and immunohistochemical analyses. For this study, 72 rats were divided into three groups: clot group (CG), bovine collagen group (BCG), and porcine collagen group (PCG). Analyses were performed on days 7, 15, 30, and 60. The histological results showed that the PCG exhibited bone neoformation starting from day 7, and after 30 days of repair, the surgical defect was completely filled in some animals. For the BCG, there was little bone neoformation activity in the initial periods, and from day 30 onwards, there was an increase in bone neoformation, with a greater increase on day 60. The data obtained in the histometric analysis reveal that, on day 30, the neoformed bone area did not vary greatly between the PCG and the BCG, though both varied from the CG. By day 60, the PCG presented a greater area of neoformation than the BCG. These results were corroborated by the immunohistochemistry results. In view of the results obtained, it can be concluded that all membranes studied in this research promoted GBR.

Dimensional evaluation of blood clot gap distances within intrabony defects following grafting and EDTA root surface treatment-experimental study in dogs

BACKGROUND

Because it is important to establish and maintain a firm blood clot to the surrounding tissues within the intrabony lesion; we have to investigate the potentials of different materials in resisting clot retraction that disrupt clot adhesion to the root surface. This study was designed to measure the gap distance created by clot retraction within the defect following intrabony defects grafting with and without root surface EDTA etching.

METHODS

Eight mongrel dogs with surgically created acute-chronic bilateral mandibular interproximal intrabony defects in the premolar-molar areas were enrolled in this study (total 8 defects per dog). Intrabony defects were divided into four groups, the first group (OFD): control open flap debridement, the second group, (EDTA treated defects) in which debridement of the defects was followed by two minute root surface etching with a neutral 24% EDTA gel followed by two minute copious saline irrigation, the third group (only grafted defects): defects received closely packed β-TCP of a particle size ranged from 150 to 500 mm, and the fourth group, (Graft + EDTA treated defects): defects were etched for 2 minutes with a neutral 24% EDTA gel and saline irrigation followed by intrabony defect fill of β-TCP. Twenty four hours post treatment, animal euthanasia was carried out for histomorphometric analysis of the tooth and root side gap distances.

RESULTS

EDTA treated group and EDTA + graft group showed statistically significant lower degree of clot shrinkage compared to both the control and only grafted group. Clot shrinkage in EDTA treated group showed no significant difference from that of the EDTA + graft group (p = 0.197). OFD and only grafted groups were found to show statistically higher clot retraction percnetage compared to both EDTA and EDTA+graft groups.

CONCLUSION

following intrabony defect debridement, blood clot undergoes clot retraction creating a micro gap with the root surface. EDTA root surface etching before graft application into the defect area significantly reduced the amount of gap distance.

Flapless immediate implant placement into fresh molar extraction socket using platelet-rich fibrin: A case report

BACKGROUND

There are some challenges concerning immediate implant placement in the molar region. Platelet-rich fibrin (PRF), an autologous biomaterial, has been used widely for periodontal intra-bony defects, sinus augmentation, socket preservation, and gingival recession. However, the literature remains scarce for reports on immediate implants with PRF, particularly in the case of fresh molar extraction socket.

CASE SUMMARY

The patient was a 43-year-old woman with maxillary molar vertical crown-root fracture. She underwent flapless immediate implant placement into the fresh molar socket with PRF. At the follow-up visit 15 d post procedure, the vascularization of soft tissue was visible. There was no swelling or pain after the surgery. Six months postoperatively, the regeneration of bone and soft tissues was visible. Subsequently, the definitive restoration was placed. The patient was satisfied with the aesthetic outcomes.

CONCLUSION

The flapless immediate implant placement into the fresh molar socket with PRF is a feasible procedure. This case report demonstrates that PRF promotes bone and soft tissue regeneration apart from having an enhanced anti-inflammatory ability. Furthermore, the procedure involves a minimally invasive technique, thus reducing the surgical complexity.

Barrier membranes: More than the barrier effect?

AIM

To review the knowledge on the mechanisms controlling membrane-host interactions in guided bone regeneration (GBR) and investigate the possible role of GBR membranes as bioactive compartments in addition to their established role as barriers.

MATERIALS AND METHODS

A narrative review was utilized based on in vitro, in vivo and available clinical studies on the cellular and molecular mechanisms underlying GBR and the possible bioactive role of membranes.

RESULTS

Emerging data demonstrate that the membrane contributes bioactively to the regeneration of underlying defects. The cellular and molecular activities in the membrane are intimately linked to the promoted bone regeneration in the underlying defect. Along with the native bioactivity of GBR membranes, incorporating growth factors and cells in membranes or with graft materials may augment the regenerative processes in underlying defects.

CONCLUSION

In parallel with its barrier function, the membrane plays an active role in hosting and modulating the molecular activities of the membrane-associated cells during GBR. The biological events in the membrane are linked to the bone regenerative and remodelling processes in the underlying defect. Furthermore, the bone-promoting environments in the two compartments can likely be boosted by strategies targeting both material aspects of the membrane and host tissue responses.

[Prerequisites for improving the method of guided bone regeneration]

The purpose of this article was to discuss the need for the introduction of the concepts of 'vicryl situational frame' and 'the plastic substrate', in which the first one updates the shape-generating aspect of reconstruction, the second one - its volume-generating aspect. The latter is described as a new surgical technique. The great importance of a new level of methodological and methodical support the method of GBR, which determines the high clinical and prognostic indicators of effectiveness was concluded.

Osseointegration of TI6Al4V dental implants modified by thermal oxidation in osteoporotic rabbits

Background

In this work, the effect of the heat treatment on Ti6Al4V implants and topical administration of growth hormone to address a better osseointegration in osteoporotic patients has been analysed.

Methods

The osseointegration process of Ti6Al4V implants modified by oxidation treatment at 700 °C for 1 h and the influence of local administration of growth hormone (GH) in osteoporotic female rabbits after 15 and 30 days of implantation have been studied. Bone response was analysed through densitometric and histomorphometric studies. Characterization of the surface was provided by scanning electron microscopy.

Results

The oxidation treatment promotes the formation of an oxide scale grown on the Ti6Al4V implants that alters the nanoroughness of the surface. Bone mineral density (BMD) increases from 0.347 ± 0.014 (commercial) to 0.383 ± 0.012 g cm−2 (modified), and bone-to-implant contact (BIC) goes from 48.01 ± 14.78 (commercial) to 55.37 ± 15.31 (modified) after 30 days of implantation.

Conclusions

The oxidation treatment on the Ti6Al4V dental implants enhances the early bone formation at the longest periods of implantation. No significant differences in the BMD and BIC results in healthy and osteoporotic rabbits were revealed with respect to the local administration of GH in the implantation site.

Influence of platelet-derived growth factor on osseous remodeling properties of a variable-thread tapered dental implant in vivo

OBJECTIVES

To evaluate the effect of platelet-derived growth factor (rhPDGF-BB) on the promotion of osteogenesis around variable-thread tapered implants in an animal model.

MATERIAL AND METHODS

Twenty-four variable-thread tapered implants were inserted in the tibia of 12 rabbits. Twelve sites received additional rhPDGF-BB released from a presoaked xenogenic bone block that was fixed supracrestally. Primary outcomes were bone-to-implant contact (BIC; in % ± SD) and percentage of medullary bone fill around the implants (PMF; in % ± SD) after 3 weeks (PDGF n = 6, no PDGF n = 6) and 6 weeks (PDGF n = 6, no PDGF n = 6).

RESULTS

Considerable crestal and medullary bone remodeling could be found around all implants. After 3 weeks, both BIC and PMF values were higher in the no PDGF group (BIC: 63% ± 10 with PDGF vs. 85% ± 5 with no PDGF; PMF: 57% ± 10 with PDGF vs. 74% ± 4 with no PDGF). After 6 weeks, the BIC difference between the two groups was less distinct (BIC: 78% ± 17 with PDGF vs. 72% ± 25 with no PDGF), whereas the PDGF group showed higher PMF values (PMF: 77% ± 5 with PDGF vs. 56% ± 10 with no PDGF).

CONCLUSIONS

The addition of rhPDGF-BB decreases early osseous crestal and medullar healing properties around dental implants. In a later phase, an increase in the cortical area as well as an increased medullar bone formation was seen. This response is likely to provide stronger secondary stability and stability in suboptimal situations involving poor-quality bone.

Effect of PDGF-BB, IGF-I growth factors and their combination carried by liposomes in tooth socket healing

This work evaluated the bone-forming potential of the platelet-derived growth factor isoform BB (PDGF-BB), insulin-like growth factor I (IGF-I), and mixed PDGF-BB/IGF-I delivered in liposomes compared with phosphate buffered saline (PBS), in the healing process of rat tooth sockets. One hundred and twelve Wistar rats were randomized into 7 groups of 16 animals each and were evaluated at 3, 7, 14 and 21 days after extraction of the maxillary second molars. The left sockets were treated with PBS (P), empty liposome (L), IGF-I in PBS (IP), IGF-I in liposome (IL), PDGF-BB in PBS (PDP), PDGF-BB in liposome (PDL) and both growth factors (GFs) together within liposomes (PDIL). The right sockets were filled with blood clot (BC). Histological and histomorphometric analyses were used to evaluate the formation of new bone and blood vessels. Immunohistochemistry was performed to evaluate the expression of osteocalcin and vascular endothelial growth factor (VEGF) during bone repair. Data were tested statistically using a Tukey's test according to a Dunn's analysis and Mann-Whitney U test followed by Kruskal-Wallis one-way analysis. Results were considered significant when p<0.05. A significantly higher percentage of bone trabeculae and a higher number of blood vessels were observed in the IL, PDL and PDIL groups (p<0.05). However, these GF-liposome groups had statistically similar results. Immunohistochemical assays first detected osteocalcin and VEGF expression at 3 days followed by a peak at 7 days. Lower immunoreactivity levels were observed in the BC, L, P, IP and PDP groups compared with the IL, PDL and PDIL groups (p<0.05). The results suggest that GFs carried by liposomes, either in isolated or mixed forms, enhanced the healing process in rat tooth sockets. The differential expression of the osteogenic markers VEGF and osteocalcin in the early phases of bone healing support these findings.

Effect of Recombinant Human Growth Hormone on Osseointegration of Titanium Implants: A Histologic and Biomechanical Study in Rabbits

To evaluate the action of recombinant human growth hormone (rhGH) on osseointegration of titanium implants in rabbits. Fourteen adult New Zealand rabbits, aged 30 weeks, were used in the study, and randomly divided into 2 groups. In each animal, 2 (2.2 mm × 6 mm) pure titanium implants were placed in the left tibia. In one group (test group), 1 IU (0.3 mg) of rhGH as a lyophilized powder was applied to each osteotomy site prior to implant placement. Only titanium implants were placed in osteotomy sites of the other group (control). Animals were humanely killed at 14 and 42 days after surgery, and samples were then prepared for histologic analysis and biomechanical test. The biomechanical test showed tensile pull-out stress values of 33.88 N/cm2 for controls and 59.26 N/cm2 for the rhGH group at 14 days and 25.99 N/cm2 and 29.69 N/cm2 for the control and the test group, respectively, at 42 days. Scanning electron microscope analysis showed more uniform and abundant bone tissue in contact with the implants for the test group at 14 days, and no differences between groups at 42 days. Furthermore, histologic analysis also showed accelerated bone repair in 14 days and a more advanced stage of bone remodeling for the rhGH-treated group when compared to controls after 42 days of repair. Such results show that the topical use of rhGH induces new bone formation in the early stages of bone repair and hence accelerates osseointegration of titanium dental implants.

Bone Replacement Materials and Techniques Used for Achieving Vertical Alveolar Bone Augmentation

Alveolar bone augmentation in vertical dimension remains the holy grail of periodontal tissue engineering. Successful dental implant placement for restoration of edentulous sites depends on the quality and quantity of alveolar bone available in all spatial dimensions. There are several surgical techniques used alone or in combination with natural or synthetic graft materials to achieve vertical alveolar bone augmentation. While continuously improving surgical techniques combined with the use of auto- or allografts provide the most predictable clinical outcomes, their success often depends on the status of recipient tissues. The morbidity associated with donor sites for auto-grafts makes these techniques less appealing to both patients and clinicians. New developments in material sciences offer a range of synthetic replacements for natural grafts to address the shortcoming of a second surgical site and relatively high resorption rates. This narrative review focuses on existing techniques, natural tissues and synthetic biomaterials commonly used to achieve vertical bone height gain in order to successfully restore edentulous ridges with implant-supported prostheses.

Tissue engineering for bone regeneration and osseointegration in the oral cavity

OBJECTIVE

The focus of this review is to summarize recent advances on regenerative technologies (scaffolding matrices, cell/gene therapy and biologic drug delivery) to promote reconstruction of tooth and dental implant-associated bone defects.

METHODS

An overview of scaffolds developed for application in bone regeneration is presented with an emphasis on identifying the primary criteria required for optimized scaffold design for the purpose of regenerating physiologically functional osseous tissues. Growth factors and other biologics with clinical potential for osteogenesis are examined, with a comprehensive assessment of pre-clinical and clinical studies. Potential novel improvements to current matrix-based delivery platforms for increased control of growth factor spatiotemporal release kinetics are highlighting including recent advancements in stem cell and gene therapy.

RESULTS

An analysis of existing scaffold materials, their strategic design for tissue regeneration, and use of growth factors for improved bone formation in oral regenerative therapies results in the identification of current limitations and required improvements to continue moving the field of bone tissue engineering forward into the clinical arena.

SIGNIFICANCE

Development of optimized scaffolding matrices for the predictable regeneration of structurally and physiologically functional osseous tissues is still an elusive goal. The introduction of growth factor biologics and cells has the potential to improve the biomimetic properties and regenerative potential of scaffold-based delivery platforms for next-generation patient-specific treatments with greater clinical outcome predictability.

Mechanisms of guided bone regeneration: a review

Post-extraction crestal bone resorption is common and unavoidable which can lead to significant ridge dimensional changes. To regenerate enough bone for successful implant placement, Guided Bone Regeneration (GBR) is often required. GBR is a surgical procedure that uses barrier membranes with or without particulate bone grafts or/and bone substitutes. There are two approaches of GBR in implant therapy: GBR at implant placement (simultaneous approach) and GBR before implant placement to increase the alveolar ridge or improve ridge morphology (staged approach). Angiogenesis and ample blood supply play a critical role in promoting bone regeneration.

Preserving soft tissue after placing implants in fresh extraction sockets in the maxillary esthetic zone and a prosthetic template for interim crown fabrication: a prospective study

STATEMENT OF PROBLEM

The technique of immediate implant placement is said to have success rates similar to those of implantation into a healed socket. An implant-supported restoration in an esthetic area must achieve a harmonious balance of functional, esthetic, and biologic imperatives to be considered effective.

PURPOSE

The purpose of this clinical study was to assess the height of the interproximal gingival papillae adjacent to immediate implants with immediate loading. The hypothesis was that specific positioning of the proximal contact areas of the interim crowns would facilitate the maintenance or regeneration of the interproximal papilla.

MATERIAL AND METHODS

Twenty-eight participants were provided implants (n=36) in the anterior maxillary area that were loaded with a specifically contoured interim crown immediately after tooth extraction. The proximal contact areas of the interim crowns were positioned 5 to 6 mm incisal to the interproximal bony crest by using a prosthetic template. Papilla height was classified according to a previously described papilla index. A comparison was made between the papilla height before the extraction, at interim crown placement after the implant placement, and at 6 and 12 months postoperatively. Parametric and nonparametric tests were used when appropriate (Kolmogorov-Smirnov). Significance was expressed at the α=.05 level. Cross tables were used to describe the changes in the papilla index score.

RESULTS

During the 1-year follow-up, the score of the distal and mesial papilla indices increased significantly (repeated-measures Friedman exact test; P=.035 and P=.002).

CONCLUSIONS

This prospective study indicated that the use of a prosthetic template for positioning an interim crown on immediately placed implants and for ensuring that the proximal contact areas of the crown with adjacent teeth are 5 to 6 mm incisal to the interproximal bony crest does not seem to hinder the maintenance or regeneration of the height of the interproximal papillae.

Bone ingrowth and vascular supply in experimental spinal fusion with platelet-rich plasma

STUDY DESIGN

Prospective investigation using a posterolateral spinal fusion (PLSF) model in rabbits.

OBJECTIVE

To assess the effects of platelet-rich plasma (PRP) alone, or with uncultured bone marrow, on bone ingrowth and angiogenesis in experimental PLSF.

SUMMARY OF BACKGROUND DATA

PRP is an autologous substance potentially beneficial to spinal fusion, because it includes several growth factors that may stimulate bone ingrowth and angiogenesis. However, the results of experimental and clinical investigations on the effectiveness of PRP in spinal fusion are controversial. This study was aimed at analyzing the influence of PRP on bone ingrowth and angiogenesis in experimental PLSF.

METHODS

Twenty White New Zealand rabbits underwent PLSF at L4-L5 level. The graft material included a ceramic carrier (Pro-Osteon 500R) loaded, in 7 rabbits, with PRP alone on the right side (group 1A) and with uncultured bone marrow in the left side (group 1B). In 7 rabbits, the ceramic carrier was used alone in the right side (group 2A), and with uncultured bone marrow in the left side (group 2B). Six rabbits (group 3) were sham operated on both right and left sides. Six months after surgery, the lumbar spine was harvested en bloc and evaluated by high-resolution radiographs (Faxitron, Wheeling, IL) and histology.

RESULTS

The radiographical outcome showed a fusion rate of 86% in groups 1A, 1B, and 2B and a fusion rate of 71% in group 2A. No specimen showed a solid fusion in the sham group. Histological analysis revealed new bone formation in the periapophyseal area in groups 1 and 2, but a complete bony bridge between the transverse processes was not observed in any specimen. In all groups, vascular density was significantly greater in the peri- compared with the interapophyseal region. In the PRP group, there was no evidence of increased vascular density in the grafted material compared with the other groups.

CONCLUSION

In experimental PLSF model in rabbits, PRP was not effective in promoting new bone formation and vascularization.

Platelet-rich plasma gel promotes regeneration of articular cartilage in knees of sheeps

OBJECTIVE

To assess the regeneration of osteochondral defects in the joint cartilage of the knee induced by autologous platelet-rich plasma (PRP).

METHODS

Osteochondral defects produced in the trochlear groove of both knees of ten sheep; defects of the right knees were filled with autologous PRP and the left knees were left unfilled. Macroscopic and microscopic evaluation was carried out 12 week later. The results were evaluated by the total score of both macroscopic and microscopic evaluations comparing the two sides through the Wilcoxon paired test.

RESULTS

Macroscopic appearance was not uniform among animals, nor was it different between the right and left knees (p=0.3125), and in no case the regenerated tissue was equal to the normal surrounding cartilage. At histological examination, apparently normal cartilage was not detected in any knee, but a poorly differentiated cartilage was present in 7 right knees, compared to 3 left knees. Fibrocartilaginous tissue was present in most of the remaining knees, with a significant difference in the overall score between right and left knees (p=0.0313).

CONCLUSION

The PRP as used in this study has reparative properties of the joint cartilage of sheep knees, mostly by stimulating the formation of a fibrocartilaginous tissue. Laboratory investigation.

In vitro assay for osteoinductive activity of different demineralized freeze-dried bone allograft

PURPOSE

Various bone graft materials have been used for periodontal tissue regeneration. Demineralized freeze-dried bone allograft (DFDBA) is a widely used bone substitute. The current widespread use of DFDBA is based on its potential osteoinductive ability. Due to the lack of verifiable data, the purpose of this study was to assess the osteoinductive activity of different DFDBAs in vitro.

METHODS

Sarcoma osteogenic (SaOS-2) cells (human osteoblast-like cells) were exposed to 8 mg/mL and 16 mg/mL concentrations of three commercial types of DFDBA: Osseo+, AlloOss, and Cenobone. The effect of these materials on cell proliferation was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. The osteoinductive ability was evaluated using alizarin red staining, and the results were confirmed by evaluating osteogenic gene expression using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

In the SaOS-2 cells, an 8 mg/mL concentration of Osseo+ and Cenobone significantly increased cell proliferation in 48 hours after exposure (P<0.001); however, in these two bone materials, the proliferation of cells was significantly decreased after 48 hours of exposure with a 16 mg/mL concentration (P<0.001). The alizarin red staining results demonstrated that the 16 mg/mL concentration of all three tested DFDBA induced complete morphologic differentiation and mineralized nodule production of the SaOS-2 cells. The RT-PCR results revealed osteopontin gene expression at a 16 mg/mL concentration of all three test groups, but not at an 8 mg/mL concentration.

CONCLUSIONS

These commercial types of DFDBA are capable of decreasing proliferation and increasing osteogenic differentiation of the SaOS-2 cell line and have osteoinductive activity in vitro.

Influence of a collagen membrane and recombinant platelet-derived growth factor on vertical bone augmentation in implant-fixed deproteinized bovine bone--animal pilot study

OBJECTIVES

Combinations of bone substitute block materials with membrane techniques as well as with growth factors are possible options to enhance the prognosis of vertical bone augmentation. Therefore, the aim of the pilot study was to compare the influence of a collagen membrane and a signal protein (rhPDGF-BB) on vertical bone augmentation with a stable fixed block material (deproteinized bovine bone [DBB]).

MATERIALS AND METHODS

In 12 rabbits, a DBB-block was implant-fixed on the tibia in a split-leg-design. Included were: DBB only (control), DBB + collagen membrane (test), DBB + rhPDGF-BB (test) and DBB + rhPDGF-BB + collagen membrane (test). 24 samples were examined after 3 (n = 12) and 6 weeks (n = 12). Calculated parameters were new bone area (NBA;%), new vertical bone height (VBH; mm). Due to the pilot character of this study, single values are shown descriptively only.

RESULTS

After 3 weeks, there were constant higher NBA values in the rhPDGF-BB-group without membrane (NBA (%) DBB: 30/16/4; DBB + membrane: 25/17/7, DBB + rhPDGF-BB: 40/33/34, DBB + rhPDGF-BB + membrane: 0/30/16; VBH (mm) DBB: 1.2/1.2/1, DBB + membrane: 0.7/0.9/1, DBB + rhPDGF-BB: 0.7/0.9/1, DBB + rhPDGF-BB + membrane: 0/1.1/1). After 6 weeks, both membrane groups showed a constant higher NBA and VBH independent to the use of rhPDGF-BB (NBA DBB: 3/0/5, DBB + membrane: 20/35/31, DBB + rhPDGF-BB: 5/8/4, DBB + rhPDGF-BB + membrane: 31/35/40; VBH DBB: 0.3/0.3/0.6, DBB + membrane: 1.6/2.4/2.1, DBB + rhPDGF-BB: 0.4/0.7/0.8, DBB + rhPDGF-BB + membrane: 1.8/2/1.8).

CONCLUSIONS

For vertical augmentation, the addition of rhPDGF-BB to DBB-blocks may increase early bone growth. In the later phase, the use of a collagen membrane enhances new bone volume and height to a significant greater extend. Even if the results are higher than those in the non-membrane groups, the low gain of bone after the short time periods still needs improvement.

Alveolar ridge augmentation for implant fixation: status review

This literature review was performed to illustrate and compare different alveolar ridge augmentation procedures before dental implant placement. The review was based on clinical and research studies listed in Pubmed. There is not enough evidence to support any single method as gold standard for any given condition, and choice seemed to be based on personal preferences. There is a lack of long-term survival data or success rates of grafting materials regarding donor and recipient sites. Although ridge splitting and distraction osteogenesis techniques eliminate donor site morbidity, circumvent the use of grafting materials, and reduce the operation time, some disadvantages and limitations should be considered. More studies are needed to compare the fate and characteristics of new bone obtained by these different procedures, as well as subsequent implant survival rates.

Is autologous platelet concentrate beneficial for post-extraction socket healing? A systematic review

The aim of this systematic review was to assess if the use of autologous platelet concentrates may be beneficial to the healing of extraction sockets. Medline, Embase and Cochrane Central Register of Controlled Trials were searched using a combination of specific search terms. Hand searching of the relevant journals and of the bibliographies of reviews was also performed. Prospective comparative studies evaluating the effect of a platelet concentrate on fresh extraction sockets were included. Outcome variables related to hard and soft tissue healing, aesthetics and postoperative discomfort were considered. A methodological study quality assessment was made. The initial search yielded 425 articles, eight were finally included. 207 tooth extractions (104 tests and 103 controls) in 115 patients were evaluated. The articles provided a broad range of variable outcomes to assess the regenerative potential of platelet concentrate and its possible benefits to the treatment. Favourable effects on hard and soft tissue healing and postoperative discomfort reduction were often reported. A large heterogeneity was found regarding study design, sample size, surgical techniques and methods for preparing platelet concentrates. Standardization of experimental design is needed in order to detect the true effect of platelet concentrates in regenerative procedures of extraction sockets.

Platelet-derived growth factor applications in periodontal and peri-implant bone regeneration

INTRODUCTION

Achieving successful tissue regeneration following traditional therapeutic protocols, combining bone grafts and barrier membranes, may be challenging in certain clinical scenarios. A deeper understanding of periodontal and peri-implant wound healing and recent advances in the field of tissue engineering have provided clinicians with novel means to obtain predictable clinical outcomes. The use of growth factors such as recombinant human platelet-derived growth factor-BB (rhPDGF) with biocompatible matrices to promote tissue regeneration represents a promising approach in the disciplines of periodontology and implantology.

AREAS COVERED

This review covers the basic principles of bone and periodontal regeneration, and provides an overview of the biology of PDGF and its potential to predictably and reproducibly promote bone regeneration in regular clinical practice. The results of preclinical and clinical human studies evaluating the effectiveness of growth-factor-enhanced matrices are analyzed and discussed.

EXPERT OPINION

Current available evidence supports the use of rhPDGF-enhanced matrices to promote periodontal and peri-implant bone regeneration.

Effect of platelet-rich plasma on peri-implant bone repair: a histologic study in dogs

The present study evaluated the effect of platelet-rich plasma (PRP) on peri-implant bone healing. A total of 9 mongrel dogs received 36 dental implants with sandblasted acid-etched surface in lower jaws in a split-mouth design: in the PRP group (n=18 implants) the implants were placed in association with PRP, and in the control group (n=18 implants) the implants were placed without PRP. Biopsies were obtained and prepared for histologic and histometric analysis after 15, 30, and 55 days of healing. The biopsies retrieved at 15 days showed delicate bone trabeculae formed by immature bone with presence of numerous osteoblasts for both groups. At 30 days the trabeculae presented reversal lines and evident lamellar disposition, where some thread spaces were filled by bone and dense connective tissue. At 55 days, bone healing was not altered in the control group, and histologic aspects were variable for the group treated with PRP. There was no significant difference between the groups for bone-to-implant contact (P>.05). PRP did not enhance bone formation around sandblasted acid-etched implants.

Transmucosal healing around peri-implant defects: crestal and subcrestal implant placement in dogs

OBJECTIVE

This study was designed to evaluate the transmucosal healing response of implants placed with the junction of the smooth surfaces, either crestal or subcrestal, into simulated extraction defects after healing periods of 1 and 3 months.

MATERIALS AND METHODS

A total of 23 Straumann SP v3.3 mm NN, SLA 10 mm implants were placed in the mandibular premolar regions of three greyhound dogs 3 months after the teeth were removed. Five control implants were placed at the crestal bone level, and test implants with surgically created peri-implant defects of 1.25 mm wide x 5 mm depth were placed either at the crestal (nine implants) or at the 2 mm subcrestal (nine implants) bone level. Implants on the right side were placed 1 month before the dogs were sacrificed, and implants on the left side were placed 3 months before sacrifice. All dogs had daily plaque control following surgery and were sacrificed 3 months after implant placement for histological and histometric analyses.

RESULTS

Mesial-distal ground sections of the control and test implant specimens showed a greater %BIC in the coronal defect region after 3 months of healing. This healing response was incomplete for the test implants compared with the control implants after a 1-month healing period. The histometric measurements for test implants placed at the crestal bone level or 2 mm subcrestal with surgically created peri-implant defects were more coronal or closer to the implant margin compared with the control implants. Additionally, the degree of osseointegration between the newly formed bone and the implant surface was similar between the test implants.

CONCLUSION

Peri-implant defects of 1.25 mm width healed with spontaneous bone regeneration around implants placed transmucosally at crestal or 2 mm subcrestal with a high degree of osseointegration after a 3-month healing period.

Evaluation of functional dynamics during osseointegration and regeneration associated with oral implants

OBJECTIVES

The aim of this paper is to review current investigations on functional assessments of osseointegration and assess correlations to the peri-implant structure.

MATERIAL AND METHODS

The literature was electronically searched for studies of promoting dental implant osseointegration, functional assessments of implant stability, and finite element (FE) analyses in the field of implant dentistry, and any references regarding biological events during osseointegration were also cited as background information.

RESULTS

Osseointegration involves a cascade of protein and cell apposition, vascular invasion, de novo bone formation and maturation to achieve the primary and secondary dental implant stability. This process may be accelerated by alteration of the implant surface roughness, developing a biomimetric interface, or local delivery of growth-promoting factors. The current available pre-clinical and clinical biomechanical assessments demonstrated a variety of correlations to the peri-implant structural parameters, and functionally integrated peri-implant structure through FE optimization can offer strong correlation to the interfacial biomechanics.

CONCLUSIONS

The progression of osseointegration may be accelerated by alteration of the implant interface as well as growth factor applications, and functional integration of peri-implant structure may be feasible to predict the implant function during osseointegration. More research in this field is still needed.

Immediate implant placement: clinical decisions, advantages, and disadvantages

Implant placement in fresh extraction sockets in conjunction with appropriate guided bone regeneration is well documented. The decision to extract teeth and replace them with immediate implants is determined by many factors, which ultimately affect the total treatment plan. The goal of this article is to review some of the important clinical considerations when selecting patients for immediate implant placement, and to discuss the advantages and disadvantages of this mode of therapy.

Recombinant human platelet-derived growth factor: biology and clinical applications

The abilities of bone to remodel, fractures to repair, and bone grafts to incorporate are all fundamental reflections of the bone remodeling cycle. This process is characterized by the recruitment and differentiation of osteoblastic and osteoclastic cell populations, whose cellular activities are coordinated and regulated by an elaborate system of growth factors and cytokines. One of the crucial biological factors responsible for reparative osseous activity is platelet-derived growth factor (PDGF). The potent stimulatory effects of PDGF as a chemoattractant and mitogen for mesenchymal cells (including osteogenic cells), along with its ability to promote angiogenesis, have been demonstrated in a variety of preclinical models predicting maxillofacial, spine and appendicular skeletal, and soft-tissue applications. The biological profile of PDGF, including its ability to recruit osteoprogenitor cells, makes it particularly suited to address the skeletal defects that are seen with comorbid conditions such as osteoporosis, diabetes, and the effects of smoking. The clinical success and safety that have been demonstrated with use of recombinant human PDGF (rhPDGF) in the repair of periodontal defects have led to U.S. Food and Drug Administration (FDA) approval of rhPDGF for this indication. Ongoing pilot and pivotal trials in the United States and internationally will continue to clarify the promising role of PDGF in the treatment of challenging skeletal disorders.

Immediate and early function of implants placed in extraction sockets of maxillary infected teeth: A pilot study

STATEMENT OF PROBLEM

Infection in tooth extraction sites has traditionally been considered an indication to postpone implant placement until the infection has been resolved.

PURPOSE

The aim of this study was to evaluate the survival rate of immediate and early-loaded implants placed immediately after extraction of teeth with endodontic and periodontal lesions or root fracture in the maxilla.

MATERIAL AND METHODS

Thirty-three patients with teeth judged to be unrestorable because of endodontic or periodontal lesions or root fracture were included in the study. After tooth extraction, 1 to 6 implants (n=76) were placed in each patient using flap or flapless surgery in fresh extraction sockets, and a fixed provisional prosthesis was placed immediately or within 36 hours. Definitive prostheses were inserted after 6 to 12 months. The treatment protocol considered initial implant and prosthesis stability and control of the inflammatory response. Clinical and radiographic analyses were performed to evaluate the treatment outcome. Data were reported using descriptive statistics.

RESULTS

After 1 year, 2 implants were lost, resulting in a 97.4% survival rate. A mean (SD) marginal bone loss of -0.91 (1.50) mm was recorded during the observation period. No signs of infection around the implants were detected at any follow-up visit. There was a tendency towards less bone loss with the flapless protocol, -0.74 (1.34) mm, versus flap, -1.02 (1.60) mm, and less bone loss for single, -0.55 (1.52) mm, versus multiple restorations, -0.86 (1.24) mm, with the flapless approach.

CONCLUSIONS

A high 1-year survival rate was achieved for immediately placed and immediately/early-loaded implants in the maxilla, despite the presence of infection in the location of the extracted teeth.

Citation classics in periodontology: a controlled study

AIM

The aims of this study were to identify the most cited articles in Periodontology published from January 1990 to March 2005; and to analyse the differences between citation Classics and less cited articles.

MATERIAL AND METHODS

The search was carried out in four international periodontal journals: Journal of Periodontology, Journal of Clinical Periodontology, International Journal of Periodontics and Restorative Dentistry and Journal of Periodontal Research. The Classics, that are articles cited at least 100 times, were identified using the Science Citation Index database. From every issue of the journals that contained a Classic, another article was randomly selected and used as a Control.

RESULTS

Fifty-five Classics and 55 Controls were identified. Classic articles were longer, used more images, had more authors, and contained more self-references than Controls. Moreover Classics had on the average a bigger sample size, often dealt with etiopathogenesis and prognosis, but were rarely controlled or randomized studies.

CONCLUSIONS

Classic articles play an instructive role, but are often non-Controlled studies.

Bone Augmentation Techniques

BACKGROUND

The advent of osseointegration and advances in biomaterials and techniques have contributed to increased application of dental implants in the restoration of partial and completely edentulous patients. Often, in these patients, soft and hard tissue defects result from a variety of causes, such as infection, trauma, and tooth loss. These create an anatomically less favorable foundation for ideal implant placement. For prosthetic-driven dental implant therapy, reconstruction of the alveolar bone through a variety of regenerative surgical procedures has become predictable; it may be necessary prior to implant placement or simultaneously at the time of implant surgery to provide a restoration with a good long-term prognosis. Regenerative procedures are used for socket preservation, sinus augmentation, and horizontal and vertical ridge augmentation.

METHODS

A broad overview of the published findings in the English literature related to various bone augmentation techniques is outlined. A comprehensive computer-based search was performed using various databases that include Medline and PubMed. A total of 267 papers were considered, with non-peer-reviewed articles eliminated as much as possible.

RESULTS

The techniques for reconstruction of bony defects that are reviewed in this paper include the use of particulate bone grafts and bone graft substitutes, barrier membranes for guided bone regeneration, autogenous and allogenic block grafts, and the application of distraction osteogenesis.

CONCLUSIONS

Many different techniques exist for effective bone augmentation. The approach is largely dependent on the extent of the defect and specific procedures to be performed for the implant reconstruction. It is most appropriate to use an evidenced-based approach when a treatment plan is being developed for bone augmentation cases.

Injectable bone substitute to preserve alveolar ridge resorption after tooth extraction: a study in dog

The aim of the present study was to assess the efficacy of a ready-to-use injectable bone substitute on the prevention of alveolar ridge resorption after tooth extraction. Maxillary and mandibular premolars were extracted from 3 Beagle dogs with preservation of alveolar bone. Thereafter, distal sockets were filled with an injectable bone substitute (IBS), obtained by combining a polymer solution and granules of a biphasic calcium phosphate (BCP) ceramic. As a control, the mesial sockets were left unfilled. After a 3 months healing period, specimens were removed and prepared for histomorphometric evaluation with image analysis. Histomorphometric study allowed to measure the mean and the maximal heights of alveolar crest modifications. Results always showed an alveolar bone resorption in unfilled sockets. Resorption in filled maxillary sites was significantly lower than in control sites. Interestingly, an alveolar ridge augmentation was measured in mandibular filled sockets including 30% of newly-formed bone. It was concluded that an injectable bone substitute composed of a polymeric carrier and calcium phosphate can significantly increase alveolar ridge preservation after tooth extraction.

The Effect of rhBMP-2 Around Endosseous Implants With and Without Membranes in the Canine Model

BACKGROUND

Bone morphogenetic protein (BMP) is a potent differentiating agent for cells of the osteoblastic lineage. It has been used in the oral cavity under a variety of indications and with different carriers. However, the optimal carrier for each indication is not known. This study examined a synthetic bioabsorbable carrier for BMP used in osseous defects around dental implants in the canine mandible.

METHODS

Twelve canines had their mandibular four premolars and first molar teeth extracted bilaterally. After 5 months, four implants were placed with standardized circumferential defects around the coronal 4 mm of each implant. One-half of the defects received a polylactide/glycolide (PLGA) polymer carrier with or without recombinant human BMP-2 (rhBMP-2), and the other half received a collagen carrier with or without rhBMP-2. Additionally, one-half of the implants were covered with a non-resorbable (expanded polytetrafluoroethylene [ePTFE]) membrane to exclude soft tissues. Animals were sacrificed either 4 or 12 weeks later. Histomorphometric analysis included the percentage of new bone contact with the implant, the area of new bone, and the percentage of defect fill. This article describes results with the PLGA carrier.

RESULTS

All implants demonstrated clinical and radiographic success with the amount of new bone formed dependent on the time and presence/absence of rhBMP-2 and presence/absence of a membrane. The percentage of bone-to-implant contact was greater with rhBMP-2, and after 12 weeks of healing, there was approximately one-third of the implant contacting bone in the defect site. After 4 weeks, the presence of a membrane appeared to slow new bone area formation. The percentage of fill in membrane-treated sites with rhBMP-2 rose from 24% fill to 42% after 4 and 12 weeks, respectively. Without rhBMP-2, the percentage of fill was 14% rising to 36% fill, respectively.

CONCLUSIONS

After 4 weeks, the rhBMP-2-treated sites had a significantly higher percentage of contact, more new bone area, and higher percentage of defect fill than the sites without rhBMP-2. After 12 weeks, there was no significant difference in sites with or without rhBMP-2 regarding percentage of contact, new bone area, or percentage of defect fill. In regard to these three outcomes, comparing the results with this carrier to the results reported earlier with a collagen carrier in this study, only the area of new bone was significantly different with the collagen carrier resulting in greater bone than the PLGA carrier. Thus, the PLGA carrier for rhBMP-2 significantly stimulated bone formation around dental implants in this model after 1 month but not after 3 months of healing. The use of this growth factor and carrier combination appears to stimulate early bone healing events around the implants but not quite to the same degree as a collagen carrier.