A prospective study of factors influencing morbidity after iliac crest harvesting for oral onlay grafting

Mass spectrometry-based proteomic applications in dental implants research

Dental implants have been established as successful treatment options for missing teeth with steadily increasing demands. Today, the primary areas of research in dental implantology revolve around osseointegration, soft and hard tissue grafting as well as peri-implantitis diagnostics, prevention, and treatment. This review provides a comprehensive overview of the current literature on the application of MS-based proteomics in dental implant research, highlights how explorative proteomics provided insights into the biology of peri-implant soft and hard tissues and how proteomics facilitated the stratification between healthy and diseased implants, enabling the identification of potential new diagnostic markers. Additionally, this review illuminates technical aspects, and provides recommendations for future study designs based on the current evidence.

Effect of a synthetic hydroxyapatite-based bone grafting material compared to established bone substitute materials on regeneration of critical-size bone defects in the ovine scapula

Lately, the potential risk of disease transmission due to the use of bovine-derived bone substitutes has become obvious, demonstrating the urgent need for a synthetic grafting material with comparable bioactive behaviour and properties. Therefore, the effect of a synthetic hydroxyapatite (HA) (Osbone®) bone grafting material on bone regeneration was evaluated 2 weeks, 1 month, and 3, 6, 12 and 18 months after implantation in critical-size bone defects in the ovine scapula and compared to that of a bovine-derived HA (Bio-Oss®) and β-tricalcium phosphate (TCP) (Cerasorb® M). New bone formation and the biodegradability of the bone substitutes were assessed histomorphometrically. Hard tissue histology and immunohistochemical analysis were employed to characterize collagen type I, alkaline phosphatase, osteocalcin, as well as bone sialoprotein expression in the various cell and matrix components of the bone tissue to evaluate the bioactive properties of the bone grafting materials. No inflammatory tissue response was detected with any of the bone substitute materials studied. After 3 and 6 months, β-TCP (Cerasorb® M) showed superior bone formation when compared to both HA-based materials (3 months: β-TCP 55.65 ± 2.03% vs. SHA 49.05 ± 3.84% and BHA 47.59 ± 1.97%; p ≤ 0.03; 6 months: β-TCP 62.03 ± 1.58%; SHA: 55.83 ± 2.59%; BHA: 53.44 ± 0.78%; p ≤ 0.04). Further, after 12 and 18 months, a similar degree of bone formation and bone-particle contact was noted for all three bone substitute materials without any significant differences. The synthetic HA supported new bone formation, osteogenic marker expression, matrix mineralization and good bone-bonding behaviour to an equal and even slightly superior degree compared to the bovine-derived HA. As a result, synthetic HA can be regarded as a valuable alternative to the bovine-derived HA without the potential risk of disease transmission.

Evaluation of the quality of life and the satisfaction level after reconstruction with anterior iliac crest graft and implant-supported fixed prosthesis treatment

PURPOSE

To evaluate oral health-related quality of life (OHRQoL) and satisfaction levels related to treatment in patients who have complete implant treatment and prosthetic rehabilitation after anterior iliac crest grafting.

MATERIALS AND METHODS

Fifty-four patients (37 F, 17 M) with a total of 487 implants placed and implant-supported fixed prosthesis treatment completed were included in the study. OHIP-14OHIP-14 scale and satisfaction Likert scale questions were used to evaluate the OHRQoL and the satisfaction levels related to the treatment applied, respectively. To compare the outcomes, the significance test and the Mann-Whitney U-test were used. One-way analyses of variance and Kruskal-Wallis were used to assess the significance of differences among or between the groups.

RESULTS

The quality of life (QoL) was higher, and the mean OHIP-14 scores were lower in women, older patients, and cases with a longer follow-up period, recorded as 13.6 ± 10.3 (p: 0.263), 12.9 ± 11.3 (p: 0.079), and 11.8 ± 9.6 (p: 0.015*), respectively. Moreover, satisfaction levels of the patients related to the treatment were 83.3%.

CONCLUSIONS

The treatment of severely atrophic jaws with anterior iliac crest for the implant and prosthetic rehabilitation has a positive effect on the QoL. This effect has increased with time, and the satisfaction levels of the patients related to this procedure were high, and their expectations regarding this treatment were met at a high level.

A matter of origin - identification of SEMA3A, BGLAP, SPP1 and PHEX as distinctive molecular features between bone site-specific human osteoblasts on transcription level

In oral and maxillofacial bone reconstruction, autografts from the iliac crest represent the gold standard due to their superior clinical performance, compared to autografts derived from other extraoral regions. Thus, the aim of our study was to identify putative differences between osteoblasts derived from alveolar (hOB-A) and iliac crest (hOB-IC) bone of the same donor (nine donors) by means of their molecular properties in 2D and 3D culture. We thereby focused on the gene expression of biomarkers involved in osteogenic differentiation, matrix formation and osteoclast modulation. Furthermore, we examined the transcriptional response to Vit.D3 in hOB-A and hOB-IC. Our results revealed different modulation modes of the biomarker expression in osteoblasts, namely cell origin/bone entity-dependent, and culture configuration- and/or time-dependent modulations. SEMA3A, SPP1, BGLAP and PHEX demonstrated the strongest dependence on cell origin. With respect to Vit.D3-effects, BGLAP, SPP1 and ALPL displayed the highest Vit.D3-responsiveness. In this context we demonstrated that the transcriptional Vit.D3-response concerning SPP1 and ALPL in human osteoblasts depended on the cell origin. The results indicate a higher bone remodeling activity of iliac crest than alveolar osteoblasts and support the growing evidence that a high osteoclast activity at the host-/donor bone interface may support graft integration.

Proteomic profiling of human bone from different anatomical sites - A pilot study

PURPOSE

The study aim is a comparative proteome-based analysis of different autologous bone entities (alveolar bone [AB], iliac cortical [IC] bone, and iliac spongiosa [IS]) used for alveolar onlay grafting.

EXPERIMENTAL DESIGN

Site-matched bone samples of AB, IC, and IS were harvested during alveolar onlay grafting. Proteins were extracted using a detergent-based (sodium dodecyl sulfate) strategy and trypsinized. Proteome analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). MaxQuant was used for peptide-to-spectrum matching, peak detection, and quantitation. Linear models for microarray analysis (LIMMA) were used to detect differentially abundant peptides and proteins.

RESULTS

A total of 1730 different proteins were identified across the 15 samples at a false discovery rate of 1%. Partial least-squares discriminant analysis approved segregation of AB, IC, and IS protein profiles. LIMMA statistics highlighted 66 proteins that were more abundant in AB then in IC (vs. 92 proteins were enriched in IC over AB). Gene Ontology enrichment analysis revealed a matrisomal versus an immune-related proteome fingerprint in AB versus IC.

CONCLUSION AND CLINICAL RELEVANCE

This pilot study demonstrates an ECM protein-related proteome fingerprint in AB and an immune-related proteome fingerprint in IS and IC.

EFFECT OF AUTOGENOUS BONE GRAFT SITE ON DENTAL IMPLANT SURVIVAL AND DONOR SITE COMPLICATIONS: A SYSTEMATIC REVIEW AND META-ANALYSIS

OBJECTIVES

This systematic review and meta-analysis was undertaken to answer the following focus questions: Is the implant survival in augmented bone utilizing iliac crest bone grafts the same as while using intraoral autologous bone grafts? Is the incidence of postoperative donor site complications the same when using iliac crest bone grafts as opposed to intraoral grafts?

METHODS

Systematic searches of electronic databases (PubMed, Embase, CENTRAL) were performed to identify studies which reported on implant survival and postoperative complications for dental implants placed in grafted partially/completely edentulous human jaws. Studies were included if: they reported on 2-piece micro-rough surface root form dental implants placed in bone-augmented completely or partially edentulous human jaws, and the jaws must have been augmented with autologous bone graft materials. Time and nature of postoperative complications must have been reported. Two investigators performed data extraction and a Cohen's unweighted kappa was calculated for inter-investigator reliability. A meta-analysis was performed for the extracted data on implant survival rate in both iliac crest grafts and intra-oral grafts. A qualitative analysis was performed on the information extracted on graft donor site complications. Quality assessment of the included studies were done using the Cochrane collaboration tool and the Newcastle-Ottawa scales.

RESULTS

A total of 23 studies were included in the final analysis. The calculated kappa ranged between 0.77-0.89 for the literature search and identification process. Fourteen studies were included with data on implant survival including five randomized controlled clinical trials. The meta-analysis of included studies revealed that the implant survival rate of dental implants placed in jaws augmented with iliac crest grafts was lower than those placed in jaws augmented with intra-oral bone grafts at 6-months [ICG = 95.8% IOG = 98.4%; P < .001], 12-months [ICG = 97.0%, IOG = 98.4%; P < .001], 24-months [ICG = 85.9%, IOG = 98.2%; P < .001], 60-months [ICG = 90.0%, IOG = 91.5%; P < .001], and at 120-months [ICG = 88.8%, IOG = 95.2%; P < .001] follow-up periods. Iliac crest grafts were also frequently associated with donor site complications including pain / discomfort, gait disturbance, and sensory disturbance.

CONCLUSIONS

This systematic review and meta-analysis demonstrates that implant survival is consistently higher in bone harvested from intraoral sites compared to iliac crest grafts. Donor site complications seemed to be a frequent finding with iliac crest grafts and mental grafts.

FUNDING

None.

REGISTRATION

The review protocol was registered with PROSPERO: International prospective register of systematic reviews (CRD42021283738).

Comparison of the 3D-Microstructure Between Alveolar and Iliac Bone for Enhanced Bioinspired Bone Graft Substitutes

In oral- and maxillofacial bone augmentation surgery, non-vascularized grafts from the iliac crest demonstrate better clinical performance than alveolar bone grafts. The underlying mechanisms are not fully understood but are essential for the enhancement of bone regeneration scaffolds. Synchrotron Radiation µ-CT at a pixel size of 2.3 μm was used to characterize the gross morphology and the vascular and osteocyte lacuna porosity of patient-matched iliac crest/alveolar bone samples. The results suggest a difference in the spatial distribution of the vascular pore system. Fluid simulations reveal the permeability tensor to be more homogeneous in the iliac crest, indicating a more unidirectional fluid flow in alveolar bone. The average distance between bone mineral and the closest vessel pore boundary was found to be higher in alveolar bone. At the same time, osteocyte lacunae density is higher in alveolar bone, potentially compensating for the longer average distance between the bone mineral and vessel pores. The present study comprehensively quantified and compared the 3D microarchitecture of intraindividual human alveolar and iliac bone. The identified difference in pore network architecture may allow a bone graft from the iliac crest to exhibit higher regeneration potential due to an increased capacity to connect with the surrounding pore network of the residual bone. The results may contribute to understanding the difference in clinical performance when used as bone grafts and are essential for optimization of future scaffold materials.

Clinical Comparation of Extra-Short (4 mm) and Long (>8 mm) Dental Implants Placed in Mandibular Bone: A Systematic Review and Metanalysis

This systematic review (SR) aimed to evaluate implant survival rate, marginal bone loss (MBL), and biological/prosthetic complications of extra-short 4 mm dental implants. An electronic search without language or date restrictions was performed in five databases and in gray literature for articles published until August 2020. Prospective cohort studies and randomized clinical trials (RCTs) that evaluated the clinical performance of extra-short 4 mm dental implants were included. Studies were independently assessed for risk of bias using the Cochrane Collaboration’s tool. The protocol of this SR was registered in the PROSPERO database under number CRD42019139709. Four studies were included in the present SR. There was no significant difference in implant survival rate (p = 0.75) between extra-short 4 mm and long implants. After 12 months of function, the extra-short implants had a significantly (p = 0.003) lower marginal bone loss (MBL) rate when compared to long implants. Extra-short implants had a lower number of biological and prosthetic complications when compared to long implants. After 12 months of follow-up, extra-short 4 mm dental implants placed in the mandible exhibit satisfactory clinical outcomes concerning implant survival rate and MBL when compared to longer implants, with a low number of biological and prosthetic complications. A higher number of RCTs with longer follow-up is necessary for the future.

MRI for the display of autologous onlay bone grafts during early healing-an experimental study

OBJECTIVES

Autologous bone grafts are the gold standard to augment deficient alveolar bone. Dimensional graft alterations during healing are not known as they are not accessible to radiography. Therefore, MRI was used to display autologous onlay bone grafts in vivo during early healing.

METHODS AND MATERIALS

Ten patients with alveolar bone atrophy and autologous onlay grafts were included. MRI was performed with a clinical MR system and an intraoral coil preoperatively (t0), 1 week (t1), 6 weeks (t2) and 12 weeks (t3) postoperatively, respectively. The graft volumes were assessed in MRI by manual segmentation by three examiners. Graft volumes for each time point were calculated and dimensional alteration was documented. Cortical and cancellous proportions of bone grafts were assessed. The intraobserver and interobserver variability were calculated. Statistical analysis was performed using a mixed linear regression model.

RESULTS

Autologous onlay bone grafts with cortical and cancellous properties were displayed in vivo in eight patients over 12 weeks. The fixation screws were visible as signal voids with a thin hyperintense fringe. The calculated volumes were between 0.12-0.74 cm³ (t1), 0.15-0.73 cm³ (t2), and 0.17-0.64 cm³ (t3). Median changes of bone graft volumes of -15% were observed. There was no significant difference between the examiners (p = 0.3).

CONCLUSIONS

MRI is eligible for the display and longitudinal observation of autologous onlay bone grafts. Image artifacts caused measurements deviations in some cases and minimized the precise assessment of graft volume. To the knowledge of the authors, this is the first study that used MRI for the longitudinal observation of autologous onlay bone grafts.

Horizontal bone grafting using equine-derived cancellous bone blocks is associated with severe complications: A prospective clinical and histological pilot study

AIMS

The aim of this prospective, clinical study was to evaluate the clinical performance and histological outcome of a new equine hydroxyapatite collagenated bone block (eHAC) for horizontal bone grafting prior to implant placement.

MATERIALS AND METHODS

Five patients (two male/three female) with a mean age of 51.6 years (range 22-66 years) and a reduced horizontal bone width of the alveolar ridge (mean 3.5 mm) underwent horizontal bone grafting using eHAC at 10 grafting sites. Reentry was performed 6.9 months after the horizontal grafting procedure. Clinical follow-up (mean 28.9 month) considered width gain of the alveolar ridge, soft tissue healing, and complications. To evaluate graft incorporation, four additional patients underwent histological assessment of equine blocks adjacent to autologous blocks 3 and 6 months after grafting.

RESULTS

The study was terminated after graft failure was observed in four of five patients. Mean horizontal bone width had increased by 3.6 ± 1.22 mm. Three out of nine implants placed had to be removed due to graft failure. Histological evaluation revealed large amounts of soft connective tissue within the grafts (mean 67.3 ± 9.5%). The proportion of new bone formation 3 months after the lateral grafting procedure revealed an average of 8.6%, compared to 11.4% after 6 to 7 months.

CONCLUSION

Lateral ridge grafting using eHAC achieved measurable horizontal width gain but revealed high rates of severe complications.

CLINICAL IMPLICATIONS

Within the limitations of this study, eHAC bone blocks cannot be recommended for horizontal bone grafting.

Complications Associated With Anterior Iliac Bone Grafting for the Reconstruction of Dentoalveolar Defects

The aim of this study is to evaluate donor- and recipient-site complications of iliac bone grafting for the reconstruction of atrophic jaws.Our study includes 86 consecutive patients with atrophic jaws who underwent iliac bone grafting surgery. At the donor site, hematoma, infection, paresthesia, chronic pain, prolonged gait disturbance, fracture of the ilium, and esthetic concerns; at the recipient site, hematoma, infection, prolonged pain, graft exposure, graft loss, and loss of the implants were evaluated.Grafting was successfully performed in all patients. The mean follow-up period was 35 months. Prolonged gait disturbance (20.9%) and paresthesia (9.3%) were the most frequently observed donor-site complications. At the recipient site, hematoma (8.1%), infection (12.8%), prolonged pain (11.6%), partial graft exposure (33.7%), total graft exposure (7%), partial graft loss (17.4%), and total graft loss (5.8%) were observed.Reconstruction of atrophic jaws can be achieved successfully with iliac bone grafting. However, there are possible donor- and recipient-site complications that have to be taken into consideration.

Detection of major histocompatibility complex molecules in processed allogeneic bone blocks for use in alveolar ridge reconstruction

OBJECTIVES

Because processed allogenic bone blocks contain remnants of cells and other organic material, the present study examined the putative presence of major histocompatibility complex (MHC) molecules in protein extracts derived from processed allogeneic bone blocks.

STUDY DESIGN

Protein content and the immunogenic potential of 3 different processed allografts (Osteograft, DIZG, Berlin, Germany; Caput femoris, DIZG, Berlin, Germany; Human Spongiosa, Charité Tissue Bank, Berlin, Germany) were assessed by protein extraction and analysis of the presence of MHC class 1 and 2 molecules prior to grafting. MHC concentration was measured by using enzyme-linked immunosorbent assay.

RESULTS

Protein content in the allograft materials varied between 0.87 and 1.61 µg protein/mg. In the allograft Human Spongiosa, no MHC was detected, whereas in the allogeneic bone blocks Osteograft and Caput femoris MHC 1 (0.04-0.037 ng/mg graft material) and in Osteograft MHC class 2 molecules were detectable.

CONCLUSIONS

The results of the present study suggest that despite thorough processing, a potential antigenicity of allografts is not eliminated. MHC molecules in allografts may sensitize the immune system.

Vitamin D deficiency in early implant failure: two case reports

An association between vitamin D deficiency and early dental implant failure is not properly verified, but its role in osteoimmunology is discussed. This article illustrates two case reports with vitamin D deficiency and early implant failure. Prior to implant placement, the first patient received crestal bone grafting with autologous material. Both patients received dental implants from different manufacturers in the molar region of the mandible. In the case of bone grafting in the first patient, all implants were placed in a two-stage procedure. All implants had to be removed within 15 days after implant placement. Vitamin D serum levels were measured: Both patients showed a vitamin D deficiency (serum vitamin D level <20 μg/l). After vitamin D supplementation, implant placement was successful in both patients. Prospective, randomized clinical trials must follow to affirm the relationship between vitamin D deficiency, osteoimmunology, and early implant failure.

Dentoalveolar reconstruction: modern approaches

PURPOSE OF REVIEW

A variety of bone grafting materials is available to facilitate the augmentation of defective alveolar ridges. This review evaluates current literature regarding bone grafting materials with emphasis on autologous and allogeneic bone block augmentation.

RECENT FINDINGS

Autogenous bone is a reliable grafting material providing predictable long-term results with high implant survival/success rates and low morbidity rates. The resorption properties of the iliac crest are well known and are compared with calvarial grafts more prominent. Recent studies demonstrated surgical techniques to prevent graft resorption after iliac crest grafting. Allogeneic block graft and implant survival rates appear promising in short-term clinical studies.

SUMMARY

At this stage, iliac crest remains the gold standard in large alveolar bone defects. Autogenous material is not a panacea; however, none of the available materials can currently surpass it. Rather, each material has its specific advantage for certain indications. Evident long-term studies of allogeneic bone grafting are lacking. Detected cells in allogeneic bone substitute material are positive for major histocompatibility complex classes I and II. Despite the promising clinical results achieved with allogeneic bone grafts, the current literature lacks sufficient data on antigenicity.