Bone quality at the implant site after reconstruction of a local defect of the maxillary anterior ridge with chin bone or deproteinised cancellous bovine bone

Autologous Tooth Granulometry and Specific Surface Area with Three Grinding Methods: An In Vitro Study

A postextraction socket becomes a clinical challenge due to the fact that a series of changes associated with bone remodelling and resorption of the socket that occur after extraction, which limits the aesthetic and functional prognosis of implant-supported rehabilitations. It has been studied that the use of the autologous tooth-derived graft (ATDG) has regenerative properties and could therefore be useful for solving this type of problem. There is no consensus in the scientific literature on a standardized protocol for the use of the autologous tooth. Therefore, the aim of the present study was to evaluate the most relevant parameters to achieve the best properties of ground ATDG using three methods, namely Gouge forceps, electric grinder, and manual, that made up the study group (SG) and compared with the control group (CG) consisting of Bio-Oss®. The sample obtained by the electric grinder had the highest value of specific surface area (2.4025 ± 0.0218 m2/g), while the particle size as average diameter (751.9 µm) was the lowest and most homogeneous of the three groups. Therefore, the electric grinder allowed for obtaining ATDG with more regenerative properties due to its specific surface-area value and particle size in accordance with the xenograft with the greatest bibliographical support (Bio-Oss®). The higher specific surface increases the reaction with the physiological media, producing faster biological mechanisms.

Socket Preservation Using Dentin Mixed with Xenograft Materials: A Pilot Study

BACKGROUND

The use of human dentin matrix could serve as an alternative to autologous, allogenic, and xenogeneic bone grafts due to its osteoinductive characteristics. The limitations of its use is tooth availability and that it is often necessary to mix it with a biomaterial.

AIM

The aim of this study was to analyze a mix of two different graft materials with different reabsorption ranges when the dentin graft material was not sufficient for full socket preservation.

METHODS

Seven socket preservation surgeries were carried out employing a mixed graft material containing 50% dentin and 50% xenograft. After four months of recovery, the implants were positioned. At the time of the prosthesis placement and implant surgery, bone samples were collected.

RESULTS

The histologic analysis revealed no inflammatory or infective reaction against the seven biopsies. The histomorphometric graft analysis revealed an amount of New Bone of 29.03 ± 6.57% after 4 months and 34.11 ± 5.02% after 8 months.

CONCLUSIONS

The two graft materials had a different volume reabsorption rate: 71% after 4 months and 90% after 8 months for dentin, and 6% after 4 months and 26% after 8 months for the xenograft. The space created by the dentin reabsorption increased the quantity of new bone.

Customized Titanium Mesh for Guided Bone Regeneration in the Posterior Mandible in a Patient Previously Treated with Bisphosphonates

We describe the restorative treatment of an 86-year-old female patient who was referred to our specialist prosthodontics clinic. Due to secondary osteoporosis, she underwent oral antiresorptive therapy with ibandronic acid for 10 years. Although she was classified as a patient at increased risk of drug-induced osteonecrosis of the jaw, she eventually signed a consent form for fixed implant-supported prosthetic rehabilitation in her 4th sextant. However, after tooth extraction, the bone ridge was too small at the intended implant positions. Therefore, guided bone regeneration was performed with a computer-aided design/computer-aided manufacturing three-dimensional printed titanium mesh. Finally, a continuous augmented hard tissue ridge above 7 mm was found, and three implants were inserted. Eventually, after four months of submerged healing, the implants were loaded with single crowns. Now, the patient is seen regularly for supportive peri-implant therapy.

Bone Augmentation for Implant Placement: Recent Advances

There are various advancements in biomaterials and methods for bone augmentation. This article aims to review the recent advances in bone augmentation for dental implants. Relevant articles on bone augmentation for dental implants were searched in PubMed/Medline, Scopus, Google Scholar, and Science Direct published in English literature published between January 1996 and March 2021. Relevant studies on bone grafts for dental implants were included and critically analyzed in this review. Various biomaterials can be used to augment bone for implant placement. Each graft procedure has advantages and disadvantages in each clinical application and needs to choose the graft material with a high success rate and less morbidity.

Horizontal guided bone regeneration on knife-edge ridges: A retrospective case-control pilot study comparing two surgical techniques

INTRODUCTION

Studies evaluating guided bone regeneration (GBR) on knife-edge ridges using absorbable membranes with staged approaches have reported various horizontal bone gains. This study compared the horizontal bone gain obtained via a conventional technique of GBR and a recently-reported technique. Bone loss during the healing process was also measured.

METHODS

Consecutive patients who underwent GBR on knife-edge ridges via a conventional technique (control group) or the Sausage Technique (test group) were included in this study. GBR was performed using a collagen membrane and deproteinized bovine bone mineral combined with an autogenous graft at a 1:1 ratio. Cone-beam computed tomography (CBCT) was performed preoperatively, postoperatively, and after the patient healed. Horizontal bone width was measured on CBCT images 2 mm apical from the top of the crest. The preoperative CBCT and posthealing CBCT were superimposed to calculate the bone gain after healing, and the preoperative and postoperative CBCT scans were superimposed to calculate the bone gain after surgery. Bone loss during healing was calculated by subtracting the width of the ridge after healing from the postoperative width.

RESULTS

The mean horizontal bone gain was significantly lower in the control group (2.7 ± 1.8 mm; 83.2%) than in the test group (5.3 ± 2.3 mm; 216.8%) (p = 0.003). The average horizontal bone loss between regeneration and implant placement was 0.9 mm in the control group (27.9%) and 2.1 mm in the test group (29.4%). While the absolute bone loss was significantly different (p = 0.012), the percentage of bone resorption was not (p = 0.608).

CONCLUSION

The new technique resulted in significantly more bone gain than a conventional GBR technique. The rate of graft resorption during healing was stable regardless of the amount of grafted material.

Survival Rates of Dental Implants in Autogenous and Allogeneic Bone Blocks: A Systematic Review

Background and Objectives: Preliminary studies emphasize the similar performance of autogenous bone blocks (AUBBs) and allogeneic bone blocks (ALBBs) in pre-implant surgery; however, most of these studies include limited subjects or hold a low level of evidence. The purpose of this review is to test the hypothesis of indifferent implant survival rates (ISRs) in AUBB and ALBB and determine the impact of various material-, surgery- and patient-related confounders and predictors. Materials and Methods: The national library of medicine (MEDLINE), Excerpta Medica database (EMBASE) and Cochrane Central Register of Controlled Trials (CENTRAL) were screened for studies reporting the ISRs of implants placed in AUBB and ALBB with ≥10 participants followed for ≥12 months from January 1995 to November 2021. The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The risk of bias was assessed via several scoring tools, dependent on the study design. Means of sub-entities were presented as violin plots. Results: An electronic data search resulted in the identification of 9233 articles, of which 100 were included in the quantitative analysis. No significant difference (p = 0.54) was found between the ISR of AUBB (96.23 ± 5.27%; range: 75% to 100%; 2195 subjects, 6861 implants) and that of ALBB (97.66 ± 2.68%; range: 90.1% to 100%; 1202 subjects, 3434 implants). The ISR in AUBB was increased in blocks from intraoral as compared to extraoral donor sites (p = 0.0003), partially edentulous as compared to totally edentulous (p = 0.0002), as well as in patients younger than 45 as compared to those older (p = 0.044), cortical as compared to cortico-cancellous blocks (p = 0.005) and in delayed implantations within three months as compared to immediate implantations (p = 0.018). The ISR of ALBB was significantly increased in processed as compared to fresh-frozen ALBB (p = 0.004), but also in horizontal as compared to vertical augmentations (p = 0.009). Conclusions: The present findings widely emphasize the feasibility of achieving similar ISRs with AUBB and ALBB applied for pre-implant bone grafting. ISRs were negatively affected in sub-entities linked to more extensive augmentation procedures such as bone donor site and dentition status. The inclusion and pooling of literature with a low level of evidence, the absence of randomized controlled clinical trials (RCTs) comparing AUBB and ALBB and the limited count of comparative studies with short follow-ups increases the risk of bias and complicates data interpretation. Consequently, further long-term comparative studies are needed.

Lateral Alveolar Ridge Augmentation with an Autogenous Bone Block Graft Alone with or without Barrier Membrane Coverage: a Systematic Review and Meta-Analysis

Objectives

To test the hypothesis of no difference in implant treatment outcome following lateral alveolar ridge augmentation with autogenous bone block graft with or without barrier membrane coverage.

Material and Methods

PubMed (MEDLINE), Embase and Cochrane library search in combination with a hand-search of relevant journals was conducted. Human studies published in English until the 8^th of February 2021 were included. Randomised controlled trials with an observation period longer than three months were included. Survival of implants and suprastructures were considered as primary outcomes measures, whereas peri-implant marginal bone loss, dimensional changes of the alveolar ridge, bone regeneration, patient-reported outcome measures, biological and mechanical complications were secondary outcome measures, as evaluated by descriptive statistics and meta-analysis including 95% confidence interval (CI).

Results

Electronic search and hand-searching resulted in 411 entries. Five randomised controlled trials characterised by low or high risk of bias fulfilled inclusion criteria. No statistically significant difference between the two treatment modalities was observed in any of the outcome measures. However, barrier membrane coverage was associated with a non-significant gain in alveolar ridge width of 0.5 mm (95% CI = -0.1 to 1.1) and diminished resorption of -0.9 mm (95% CI = -2.4 to 0.7) compared with no barrier membrane coverage.

Conclusions

Comparable implant treatment outcomes were revealed following lateral alveolar ridge augmentation with autogenous bone block graft alone with or without barrier membrane coverage. However, postoperative dimensional changes of the augmented seems to be diminished with the use of barrier membrane coverage as evaluated by two-dimensional linear measurements.

Preliminary Animal Study on Bone Formation Ability of Commercialized Particle-Type Bone Graft with Increased Operability by Hydrogel

The purpose of this study was to evaluate the bone-generating ability of a new bovine-derived xenograft (S1-XB) containing hydrogel. For control purposes, we used Bio-Oss and Bone-XB bovine-derived xenografts. S1-XB was produced by mixing Bone-XB and hydrogel. Cell proliferation and differentiation studies were performed to assess cytotoxicities and cell responses. For in vivo study, 8 mm-sized cranial defects were formed in 16 rats, and then the bone substitutes were transplanted into defect sites in the four study groups, that is, a Bio-Oss group, a Bone-XB group, an S1-XB group, and a control (all n = 4); in the control group defects were left empty. Eight weeks after surgery, new bone formation areas were measured histomorphometrically. In the cell study, extracts of Bio-Oss, Bone-XB, and S1-XB showed good results in terms of the osteogenic differentiation of human mesenchymal stem cells (hMSCs) and no cytotoxic reaction was evident. No significant difference was observed between mean new bone areas in the Bio-Oss (36.93 ± 4.27%), Bone-XB (35.07 ± 3.23%), and S1-XB (30.80 ± 6.41%) groups, but new bone area was significantly smaller in the control group (18.73 ± 5.59%) (p < 0.05). Bovine-derived bone graft material containing hydrogel (S1-XB) had a better cellular response and an osteogenic effect similar to Bio-Oss.

Histological Aspects of a Novel Technique Used for the Management of Infections Secondary to Sinus Bone Grafting

Recently, a technical note describing a promising method for the management of infections after sinus bone grafting by irrigating the corresponding area with hydrogen peroxide based solution with an aid of a drain has been published. The aim of this paper was to present the histological and radiological results of the above mentioned technique. A total of 17 patients who have presented with infections secondary to sinus bone grafting enrolled in the study. During implant placement, bone was collected from the originally grafted site with a trephine burr for radiological examination via micro-computed tomography and histological examination. According to the results of the current study, Bio-Oss acted as a scaffold, and mature fibrous bone formed trabeculae, which assembled to an interlinked trabecular structure. Average results obtained from the microradiography confirmed the higher percentage of Bio-Oss (27.21% ± 3.31%) at the corresponding area; whereas the amount of newly formed bone was slightly lower (6.79% ± 1.13%) As a conclusion, this simple and minimally invasive technique might be beneficial in avoiding removal of bone graft material and could help in rescuing the former laborious procedure.

Puerarin improves graft bone defect through microRNA‑155‑3p‑mediated p53/TNF‑α/STAT1 signaling pathway

Bone graft defects may lead to dysfunction of bone regeneration and metabolic disorders of bone mesenchymal stem cells (BMSCs). Puerarin has demonstrated pharmacological activities in the treatment of human metabolic diseases. The purpose of the present study was to investigate the role of puerarin and to explore its possible protective mechanism of action in rats with bone grafts. A bone graft rat model was established using bone grafting surgery and the rats received puerarin or PBS. Reverse transcription-quantitative PCR, western blot, TUNEL, immunofluorescence and immunohistochemistry assays were used to analyze the beneficial effects of puerarin on bone repair. The results demonstrated that puer-arin effectively ameliorated pathological graft bone defects, decreased bone loss and apoptosis of BMSCs, promoted BMSC proliferation and differentiation, and increased bone mass and the parameters of bone formation in rats with bone grafts. Puerarin decreased the levels of pro-inflammatory cytokines [tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-17A, IL-6 and transforming growth factor (TGF)-β1] and increased the levels of anti-inflammatory cytokines (IL-2 and IL-10) in the serum compared with the PBS group. Puerarin treatment was associated with lower serum alanine transaminase, glutamic oxaloacetic transaminase, γ-glutamyl transferase, alkaline phosphatase, direct bilirubin and total bilirubin levels compared with those in the PBS group in experimental rats. The expression of microRNA-155-3p (miR-155-3p) was upregulated, whereas that of p53, TNF-α and signal transducer and activator of transcription (STAT)1 was downregulated in BMSC cultures of puerarin-treated rats. In vitro assay demonstrated that knockdown of miR-155-3p increased p53, TNF-α and STAT1 expression in BMSCs, and blocked puerarin-regulated p53/TNF-α/STAT1 signaling. Most importantly, miR-155-3p knockdown inhibited puer-arin-regulated apoptosis, proliferation and differentiation of BMSCs. Moreover, the results demonstrated that puerarin regulated vascular endothelial growth factor expression via the miR-155-3p signaling pathway. In conclusion, the results of the present study demonstrated that the upregulation of miR-155-3p induced by puerarin promoted BMSC differentiation and bone formation and increased bone mass in rats with bone grafts, thereby supporting the potential application of puerarin in the prevention of bone graft defects.

Bone Formation in Grafts with Bio-Oss and Autogenous Bone at Different Proportions in Rabbit Calvaria

Background

The aim of this study was to assess the volumetric stability and bone formation in grafts with Bio-Oss and autogenous bone at different proportions in rabbit calvaria. Material and Methods. Ten rabbits received four titanium cylinders in their calvaria and randomly divided into the following groups: Group I: Bio-Oss (100%), Group II: Bio-Oss (75%) + autogenous bone (25%), Group III: Bio-Oss (50%) + autogenous bone (50%), and Group IV: autogenous bone (100%). After twelve weeks, the animals were euthanized, and samples were collected for clinical and histological analysis.

Results

Clinical analysis showed that Groups I (90.43 ± 8.99) and II (90.87 ± 7.43) had greater dimensional stability compared to Group IV (P=0.0005). Histologically, Groups I, II, and III showed areas of bone formation with particles of biomaterial remaining in close contact with the newly formed bone. However, there were no significant differences between the groups regarding the newly formed bone area.

Conclusion

It was concluded that the use of Bio-Oss either alone or associated with the autogenous bone at a proportion of 25% showed superior dimensional stability compared to the use of autogenous bone in the proposed experimental model.

Does preservation of the socket decrease marginal bone loss in the mandible after extraction of first molars?

The quality of the bone plays an important part in marginal bone loss (MBL) around dental implants. The aim of this study was to compare MBL around implants the sockets of which had been preserved with the bone around healed sites in the mandible after extraction of first molars. It was a prospective, cohort study in which subjects were divided into three groups (n=30 in each): dental implants were placed six months after preservation of the socket in the first group, eight weeks after tooth extraction in the second, and six months after tooth extraction in the third. The changes between the marginal bone level after loading of the implant and 12, 24, and 36 months later were considered to be the MBL. Age and sex were the variables studied, the condition of the bone (healed socket or preservation) was a predictive factor, and MBL was the outcome. Analysis of variance was used to compare MBL and age among groups. There were no differences in the mean MBL among the three groups 12, 24, and 36 months after loading (p=0.55, p=0.22, p=0.38, respectively). Preservation of the socket did not seem to affect MBL of the first molar of the mandible.

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.

Stem Cells for the Oromaxillofacial Area: Could they be a promising source for regeneration in dentistry?

Oromaxillofacial tissues (OMT) are composed of tooth and bone, together with nerves and blood vessels. Such a composite material is a huge source for mesenchymal stem cells (MSCs) that can be obtained with ease from extracted teeth, teeth structures and socket blood, flapped gingiva tissue, and mandibular/maxillar bone marrow. They offer a biological answer for restoring damaged dental tissues such as the regeneration of alveolar bone, prevention of pulp tissue defects, and dental structures. Dental tissue-derived mesenchymal stem cells share properties with bone marrow-derived mesenchymal stem cells and there is a considerable potential for these cells to be used in different stem cell-based therapies, such as bone and nerve regeneration. Dental pulp tissue might be a very good source for neurological disorders whereas gingiva-derived mesenchymal stem cells could be a good immune modulatory/suppressive mediators. OMT-MSCs is also promising candidates for regeneration of orofacial tissues from the perspective of developmental fate. Here, we review the fundamental biology and potential for future regeneration strategies of MSCs in oromaxillofacial research.

Man as a living bioreactor: Long-term histological aspects of a mandibular replacement engineered in the patient's own body

In 2016, we reported the world's first reconstruction of a mandibular discontinuity defect using a custom-made bone transplant that had been prefabricated in the gastrocolic omentum using tissue engineering strategies. However, the tissue of an engineered human neomandible has not been evaluated histologically until now. The current study assessed the long-term histological characteristics of biopsies of the neomandible 9months after transplantation. Histological analysis showed an increased amount of vital mineralized bone tissue after 10months, in comparison to biopsies obtained earlier. The engineered bone covered the surface of the bone substitute material but also grew out typical structures of cancellous bone tissue without a core of BioOss. The amount of induced bone tissue was 32% in the biopsy. In addition, the soft tissue showed an alignment of the connective tissue fibres parallel to the trabecular bone. Increasing time and mechanical forces at the mandible led to an increased amount of mineralized tissue and remodelling of the connective tissue fibres after transplantation. Further research should focus on developing advanced scaffold materials, as the outer titanium mesh cage leads to complications.

Guided Bone Regeneration for the Reconstruction of Alveolar Bone Defects

BACKGROUND

Guided bone regeneration (GBR) is the most common technique for localized bone augmentation.

PURPOSE

The purpose of this review was to categorize and assess various GBR approaches for the reconstruction of human alveolar bone defects.

MATERIALS AND METHODS

Electronic search of four databases including PubMed/Medline, EMBASE, Web of Science, and Cochrane and hand searching were performed to identify human trials attempting GBR for the reconstruction of alveolar bony defects for at least 10 patients from January 2000 to August 2015. To meet the inclusion criteria, studies had to report preoperative defect dimensions in addition to outcomes of bone formation and/or resorption.

RESULTS

Twenty-five human clinical trials were included of which 17 used conventional technique that is the use of space maintaining membrane with bone grafting particles (GBR I). Application of block bone graft with overlying membrane and particulate fillers was reported in seven studies (GBR II), and utilizing cortical bone block tented over a defect preserving particulate fillers was reported by one study (GBR III). A wide range of initial defects' sizes and treatment results were reported.

CONCLUSIONS

This review introduces a therapeutically oriented classification system of GBR for treating alveolar bone defects. High heterogeneity among studies hindered drawing definite conclusions in regard to superiority of one to the other GBR technique.

Case presentation of two patients using diagonal platform-switched double implants for maxillary single-first-molar replacement as the alternative of a single-tooth implant

A single-tooth implant restoration is generally performed for maxillary single-first-molar replacement. If the interdental space between the second premolar and the second molar is large enough, a double-implant placement can be performed to avoid creating mesiodistal cantilever and to distribute occlusal loading forces.

If there is not adequate space for a double-implant placement to be performed mesiodistally along the crest of the alveolar ridge line, they should be placed along a diagonal line offset lingually to increase the space. This procedure has two primary advantages. First, greater stability is provided by a double-implant placement. Resistance to lateral forces (palatal-buccal) is much stronger than two implants placed along the alveolar crest ridge line. Residual palatal and buccal bone can provide support against occlusal forces, provided that there is adequate residual bone in these regions.

If anatomical conditions are favorable, the placement of two diagonal implants in the palatal and buccal residual bones can be a rational procedure.

We report on two typical patients. The progress of these patients was followed using computed tomography for 7 and 6 years, respectively.

Complications related to bone augmentation procedures of localized defects in the alveolar ridge. A retrospective clinical study

PURPOSE

This retrospective clinical study aims to evaluate complications after augmentation of localized bone defects of the alveolar ridge.

METHODS

From standardized registrations, the following complications related to bone augmentation procedures were recorded: soft tissue dehiscence, infection, sensory disturbance, additional augmentation procedures needed, and early implant failure.

RESULTS

A total of 223 patients (132 women, 91 men; mean age 23.5 years; range 17-65 years) with 331 bone defects had bone augmentation performed into which 350 implants were placed. Soft tissue dehiscence occurred in 1.7 % after GBR procedures, 25.9 % after staged horizontal ridge augmentation, and 18.2 % after staged vertical ridge augmentation. Infections were diagnosed in 2 % after GBR procedures, 12.5 % after sinus floor elevation (SFE) (transcrestal technique), 5 % after staged SFE, 11 % after staged horizontal ridge augmentation, and 9 % after staged vertical ridge augmentation. Additional augmentation procedures were needed in 2 % after GBR procedures, 37 % after staged horizontal ridge augmentation, and 9 % after staged vertical ridge augmentation. A total of six early implant failures occurred (1.7 %), four after GBR procedures (1.6 %), and two (12 %) after staged vertical ridge augmentation.

CONCLUSIONS

Predictable methods exist to augment localized defects in the alveolar ridge, as documented by low complication rates and high early implant survival rates.

High-Temperature Sintering of Xenogeneic Bone Substitutes Leads to Increased Multinucleated Giant Cell Formation: In Vivo and Preliminary Clinical Results

The present preclinical and clinical study assessed the inflammatory response to a high-temperature-treated xenogeneic material (Bego-Oss) and the effects of this material on the occurrence of multinucleated giant cells, implantation bed vascularization, and regenerative potential. After evaluation of the material characteristics via scanning electron microscopy, subcutaneous implantation in CD-1 mice was used to assess the inflammatory response to the material for up to 60 days. The clinical aspects of this study involved the use of human bone specimens 6 months after sinus augmentation. Established histologic and histomorphometric analysis methods were applied. After implantation, the material was well integrated into both species without any adverse reactions. Material-induced multinucleated giant cells were observed in both species and were associated with enhanced vascularization. These results revealed the high heat treatment led to an increase in the inflammatory tissue response to the biomaterial, and a combined increase in multinucleated giant cell formation. Further clarification of the differentiation of the multinucleated giant cells toward so-called osteoclast-like cells or foreign-body giant cells is needed to relate these cells to the physicochemical composition of the material.

Are there specific indications for the different alveolar bone augmentation procedures for implant placement? A systematic review

Bone resorption following tooth loss often interferes with dental implant placement in a desired position, and requires additional bone augmentation procedures. Many techniques have been described to augment and reconstruct alveolar ridge width and height. The aim of this study was to systemically review whether there is evidence to provide indications for the various bone augmentation procedures based on defect dimension and type. An electronic search of the Medline database and Cochrane library, complemented by a manual search, was performed. Inclusion criteria for partial edentulism were: clinical trials on bone augmentation procedures in preparation or at the time of implant placement, reporting preoperative and postoperative dimensions of the ridge. For edentulous patients, studies were included when providing the data on ridge and defect description, or the amount of augmentation achieved. The search yielded 53 publications for partially edentulous patients and 15 publications for edentulous patients. The literature provides evidence that dehiscence and fenestrations can be treated successfully with guided bone regeneration (GBR) at the time of implant placement (mean implant survival rate (MISR) 92.2%, mean complication rate (MCR) 4.99%). In partially edentulous ridges, when a horizontal defect is present, procedures such as staged GBR (MISR 100%, MCR 11.9%), bone block grafts (MISR 98.4%, MCR 6.3%), and ridge expansion/splitting (MISR 97.4%, MCR 6.8%) have proved to be effective. Vertical defects can be treated with simultaneous and staged GBR (MISR 98.9%, MCR 13.1% and MISR 100%, MCR 6.95%, respectively), bone block grafts (MISR 96.3%, MCR 8.1%), and distraction osteogenesis (MISR 98.2%, MCR 22.4%). In edentulous patients, there is evidence that bone block grafts can be used (MISR 87.75%), and that Le Fort I osteotomies can be applied (MISR 87.9%), but associated with a high complication rate. The objective of extracting specific indications for each procedure could not be fully achieved due to the heterogeneity of the studies available. Further studies on bone augmentation procedures should report precise preoperative and postoperative measurements to enable a more exact analysis of the augmentation procedure, as well as to provide the clinician with the rationale for choosing the most indicated surgical approach.

Horizontal augmentation of thin maxillary ridge with bovine particulate xenograft is stable during 500 days of follow-up: preliminary results of 12 consecutive patients

PURPOSE

The purpose of our evaluation was to determine the stability of the horizontal augmentation of the anterior maxilla using particulate bovine xenograft under a membrane. The hypothesis to be tested was that bovine particulate graft material is effective for augmenting the narrow ridge of the anterior maxilla and can maintain its augmentation dimension within 1 mm over time.

MATERIALS AND METHODS

A consecutive series of 12 patients who received a bovine particulate graft were evaluated in a retrospective manner. Using a standardized method, their cone beam scans were measured for width at 3 vertical locations preoperatively (T0), immediately after the augmentation (T1), 3 to 6 months after augmentation and before implant placement (T2), immediately after implant placement (T3), and at the longest postoperative point (T4). One examiner, who was not involved in the surgical procedures, measured all the radiographs. The intraexaminer error approximated 0.2 mm in all areas of measurements. A linear mixed effects model was used to determine the stability of the augmentation over time.

RESULTS

The most coronal aspect of the crest had the least width augmentation. The midway region and apical region had the greatest width changes (P < .001). Within the sample size, there were no statistically significant differences in width changes over time after augmentation was performed.

CONCLUSIONS

Within the limitations of this sample, horizontal ridge augmentation using bovine particulate material under a membrane was stable over time in the anterior maxilla.

Bone quality and quantity of the anterior maxillary trabecular bone in dental implant sites

OBJECTIVES

The aim of this study was to investigate the characteristics of implant sites on the edentulous alveolar ridge in the anterior maxilla. We studied the bone quantity and quality of implant sites at the anterior maxilla using CT images for the 33 implant sites on patients who underwent dental implant therapy in our Department since 2006.

MATERIALS AND METHODS

Computed tomography (CT) images of 33 patients (20 women: 13 men) encompassing 33 implant sites were chosen and examined. The recipient sites for implant placement were determined based on CT data using an implant planning software (Simplant 11.0). The mean bone density values in Hounsfield unit (HU) were recorded using Simplant for both the simulated implant areas and the trabecular bone width. We classified the edentulous alveolar ridge and bone quality according to a classification based on Lekholm and Zarb (1985).

RESULTS

Incisors had higher bone densities than canines. Women had lower bone densities than men. Canines displayed greater trabecular bone density and alveolar bone widths than incisors. No maxillary sites were judged to have a bone quality of 1 in this group. Quality 3 accounted for 69.7% of the total samples.

CONCLUSIONS

An assessment of bone quality in the anterior alveolar ridge may well reflect age-related systemic pathological conditions and should be used in dental implant treatment planning to avoid associated risk factors.

Histologic and Histometric Evaluation of Bovine Cancellous Bone and Beta-Tricalcium Phosphate 45 Months After Grafting in Maxillary Sinus

The aim of this report is to determine the long-term histologic and histometric evaluation of beta-tricalcium phosphate (beta-TCP) and bovine cancellous bone grafted into the left maxillary sinus of a patient in order to augment the sinus floor to prepare it for receiving an implant. Beta-TCP and bovine cancellous bone (BCB) were grafted into the left maxillary sinus at the extracted sites of maxillary left first and second molars of a 62-year-old male patient. Using osteotome technique, 45 months later, core biopsies were taken for histologic and histometric comparison of the newly formed bone. Histometric and histologic evaluation of both specimens revealed a normal maxillary bone structure with 23.08% calcified bone and 76.92% marrow and connective tissue for the beta-TCP grafted site, and 24.81% calcified bone with 75.19% marrow and connective tissue for the BCB grafted site. No residual grafting material was seen in either specimen. Both beta-TCP and BCB were completely resorbed and replaced by new bone 45 months after grafting. Histologic results of the newly formed bone were similar for both grafting materials.

Restoration of a peri-implant defect by platelet-rich fibrin

OBJECTIVE

The objective of this study was to evaluate the application of platelet-rich fibrin (PRF) into a peri-implant defect in vivo.

STUDY DESIGN

Eight New Zealand white rabbits were used for this study. Two peri-implants with defects sized 3.0 × 5.0 mm (width × length) were prepared after drilling to host the dental implant in the tibia. Subsequently, the 2 dental implants were installed (diameter, 3.0 mm and length, 8.0 mm). In the experimental group, PRF was applied into the bony defect. In the control group, the peri-implant defect was left unfilled. The animals were humanely killed 8 weeks after implantation and histomorphometric analysis was done.

RESULTS

In the histomorphometric analysis, mean new bone formation was 29.30% ± 7.50% in the experimental group and 11.06% ± 8.94% in the control group (P = .020). Mean bone-to-implant contact was 39.43% ± 7.39% in the experimental group and 17.11% ± 8.12% in the control group (P = .006).

CONCLUSIONS

In the animal model, peri-implant defect sized 3.0 × 5.0 mm (width × length) was successfully repaired by the application of PRF alone.

Hydroxyapatite crystallinity does not affect the repair of critical size bone defects

Objective

The physicochemical properties of hydroxyapatite (HA) granules were observed to affect the biological behavior of graft materials. The aim of this work was to analyze the tissue response of two HA granules with different crystallinity and Ca/P ratio in vivo.

Material and Methods

The HA granules were produced in the Biomaterials Laboratory (COPPE/UFRJ). The testing materials were HA granules presenting a Ca/P molar ratio of 1.60 and 28% crystallinity (HA-1), and a Ca/P molar ratio of 1.67 and 70% crystallinity (HA-2). Both HAs were implanted into a critical-size calvaria rat defects.

Results

To note, in the control group, the bone defects were filled with blood clot only. Descriptive and histomorphometric analyses after 1, 3, and 6 months postoperatively showed mild inflammatory infiltrate, mainly comprising macrophage-like and multinucleated giant cells, and an increase in the volume density of the fibrous tissues (p<0.05), which was in contrast to the similar volume density of the newly formed bone and biomaterials in relation to the control group.

Conclusion

Thus, we concluded that HA-1 and HA-2 are biocompatible and non-degradable, and that crystallinity does not affect bone repair of critical size defects.

Long-term rabbits bone response to titanium implants in the presence of inorganic bovine-derived graft

This study evaluated bone responses to titanium implants in the presence of an inorganic graft material. The bilateral mandible incisors of 24 rabbits were surgically extracted and one of the exposed sockets, chosen at random, was filled with an inorganic xenogenic bone graft (Gen-ox®), whereas the remaining socket was left to heal naturally and served as a control. After 60 days, titanium implants were inserted in the specific areas, and on days 0, 30, 60, and 180 after the implant insertions, six animals of each group were killed. Digital periapical radiography of implant region was obtained and vertical bone height (VBH) and bone density (BD) were evaluated by digital analysis system. In the undecalcified tissue cuts, bone-to-implant contact (BIC) and bone area (BA) within the limits of the implant threads were evaluated and compared statistically by means of two-way ANOVA and Tukey's test (ρ < 0.05). No significant differences were detected in VBH and BA, either between groups or between different experimental intervals. The BD was significantly higher in the experimental group than in the control group in all the intervals tested, but there were no significant differences by interval. The BIC was statistically lower in the control group on day 0; however, a significant increase was observed on days 60 and 180 (ρ < 0.05). The use of an inorganic xenograft prior to insertion of a titanium implant did not interfere with the course of osseointegration.

Synthesis of three-dimensional calcium carbonate nanofibrous structure from eggshell using femtosecond laser ablation

BACKGROUND

Natural biomaterials from bone-like minerals derived from avian eggshells have been considered as promising bone substitutes owing to their biodegradability, abundance, and lower price in comparison with synthetic biomaterials. However, cell adhesion to bulk biomaterials is poor and surface modifications are required to improve biomaterial-cell interaction. Three-dimensional (3D) nanostructures are preferred to act as growth support platforms for bone and stem cells. Although there have been several studies on generating nanoparticles from eggshells, no research has been reported on synthesizing 3D nanofibrous structures.

RESULTS

In this study, we propose a novel technique to synthesize 3D calcium carbonate interwoven nanofibrous platforms from eggshells using high repetition femtosecond laser irradiation. The eggshell waste is value engineered to calcium carbonate nanofibrous layer in a single step under ambient conditions. Our striking results demonstrate that by controlling the laser pulse repetition, nanostructures with different nanofiber density can be achieved. This approach presents an important step towards synthesizing 3D interwoven nanofibrous platforms from natural biomaterials.

CONCLUSION

The synthesized 3D nanofibrous structures can promote biomaterial interfacial properties to improve cell-platform surface interaction and develop new functional biomaterials for a variety of biomedical applications.

Simultaneous versus two-stage implant placement and guided bone regeneration in the canine: histomorphometry at 8 and 16 months

AIM

To compare the effect of timing of implant placement and guided bone regeneration (GBR) procedure on osseointegration and newly formed bone at 8 and 16 months.

MATERIAL AND METHODS

In seven dogs, four different sites were bilaterally established: (1) an implant placed in a 6-month healed (6m-GBR) bovine bone mineral (BBM) grafted site; (2) a simultaneously placed implant with the grafted BBM (Si-GBR) followed by a membrane coverage; (3) an implant placed in a membrane-protected non-grafted defect; and (4) an implant placement in a naturally healed site (Cont). Histomorphometry was obtained at 8 and 16 months post-implant placement. Bone-implant contact (BIC), crestal bone resorption (CBR), vertical intra-bony (VIB) defect, bone (BAF) and particle (PAF) area fractions, and osteoconductivity (CON) levels were measured.

RESULTS

In all sites, BIC ranged between 62% and 79% with no significant differences. PAF ranged from 17% to 27%, with no effect of time. At 8 and 16 months, BAF was significantly smaller at the Si-GBR site when compared with all other sites, CON was significantly greater at the 6m-GBR site, and CBR and VIB were significantly smaller at the 6m-GBR when compared with the Si-GBR sites.

CONCLUSIONS

The simultaneous and delayed techniques both showed a similar osseointegration level over time. However, the staged approach showed enhanced newly formed bone, higher osteoconduction around the grafted mineral, less CBR, and smaller vertical bone defect over time compared with the combined approach.

A Novel Ultra-porous Titanium Dioxide Ceramic with Excellent Biocompatibility

The current study compares biocompatibility, cell growth and morphology, pore diameter distribution, and interconnectivity of a novel titanium dioxide (TiO2) bone graft substitute granules with three different commercially available bone graft granules Natix®, Straumann® BoneCeramic, and Bio-Oss®. Human primary mesenchymal stem cells were cultured on the bone graft substitutes and cell viability and proliferation were evaluated after 1 and 3 days. The microstructural properties of the bone graft substitutes were evaluated by scanning electron microscopy, micro-computed tomography analysis, and mechanical testing. The cell viability and proliferation, porosity, interconnectivity, open pore size, and surface area-to-volume ratio of TiO2 granules were significantly higher than commercial bone granules (Bio-Oss® and Straumann ® BoneCeramic).

Evaluation of aesthetics of implant-supported single-tooth replacements using different bone augmentation procedures: a prospective randomized clinical study

OBJECTIVES

The aim of this study was to evaluate the aesthetics of implant-supported single-tooth replacements using different augmentation procedures in a prospective study with the use of an objective rating index and with a subjective patient questionnaire, and to compare the results with each other.

MATERIAL AND METHODS

Ninety-three patients with a single-tooth gap in the anterior zone of the maxilla were selected for the study. All patients had a local bone defect that needed augmentation before placement of an endosseous implant with sufficient initial stability. Aesthetics of the implant-supported crown and adjacent mucosa was rated by a prosthodontist 1 year after placement of the porcelain crown. Aesthetics was rated using the Implant Crown Aesthetic Index. A subjective appreciation of the final result was assessed with a patient questionnaire.

RESULTS

The Implant Crown Aesthetic Index reveals a mean overall score of 4.8, with an acceptable result in 66% of the cases. Results of the satisfaction questionnaire reveal a mean overall score of 8.5 with an acceptable result in 100% of the cases. There is no correlation between results of the Index and the questionnaire for the overall and the crown score. The patients' opinion and the professionals' opinion about the peri-implant mucosa do show a significant correlation.

CONCLUSIONS

The peri-implant mucosa is rated as less satisfactory than the implant-supported crown by both the dental professional and patients. The dental professional was less satisfied with respect to the total result and results of the crown than the patients.

Histologic and Histomorphometric Evaluation of Alveolar Ridge Augmentation Using Bone Grafts and Titanium Micromesh in Humans

BACKGROUND

Recently, the use of titanium micromesh for alveolar bone augmentation has drawn interest; however, only limited histologic data are available on the quality of the bone regenerated. Therefore, this study compared the use of 100% intraoral autogenous bone to a combination of intraoral autogenous bone (70%) and bovine porous bone mineral (BPBM) (30%) for alveolar ridge augmentation with titanium micromesh histologically and histomorphometrically.

METHODS

Twelve partially edentulous patients required alveolar bone augmentation before implant insertion because of ridge resorption. The defect sites, six in the maxilla and six in the mandible, were reconstructed with particulate autologous bone (control group, N = 6) or a mixture of autologous bone and BPBM (test group, N = 6) in combination with titanium micromesh. Core biopsies were taken from the defect sites 8 to 9 months after grafting at the time of implant insertion.

RESULTS

Newly formed compact bone with a well-organized lamellar pattern was identified in all specimens. In the samples taken from the test group, the BPBM particles were surrounded completely by newly formed bone with no signs of resorption. The mean total bone volume was 62.38% +/- 13.02% in the control group and 52.88% +/- 11.47% in the test group. The soft tissue volume was 37.61% +/- 13.02% and 29.96% +/- 12.58%, respectively, and the residual BPBM volume was 17.15% +/- 2.72% in the test group. No statistical difference was observed in the histologic parameters evaluated, irrespective of graft type and site (P >0.05).

CONCLUSION

Within the limits of this study, BPBM (30%) in combination with autogenous bone (70%) did not yield a lower percentage of new bone formed compared to autogenous bone alone in ridge augmentation with titanium micromesh.