Systematic analysis on the efficacy of bone enhancement methods used for success in dental implants

Characterization of immunologically detectable T-cell sensitization, Immunohistochemical detection of pro-inflammatory cytokines, and clinical parameters of patients after allogeneic intraoral bone grafting procedures: a prospective randomized controlled clinical trial in humans

BACKGROUND

The null hypotheses were tested that intraoral bone augmentation using two different allogeneic materials has no impact on the patient's blood levels of material-specific lymphocytes and on the immunohistochemical detection of pro-inflammatory cytokines IL-1α, IL1ß and TNF-α and T-cell markers CD4, CD8 in biopsies of the test groups.

METHODS

In this prospective RCT, 60 systemically healthy participants were randomly assigned to two allogeneic test groups (1: Maxgraft®, freeze-dried, multiple donors, and 2: Puros®, solvent-dehydrated, single donor) and an autologous control group (10 patients). Plasma samples were collected pre-(T1) and postoperatively (2 weeks (T2) and 4 months (T3)). The Lymphocyte Transformation Test (LTT) was used for analyzing levels of transformed lymphocytes for type IV immune reactions by 3H-thymidine activity. Bone biopsies were harvested at T3 and immunohistochemically analyzed for IL-1α, IL1ß, TNF-α, CD4, CD8 and correlated with the immunological and clinical findings.

RESULTS

A statistically significant difference between the tested materials was observed for LTT measurements at T3 (p = 0.033). Furthermore, three groups were identified: Group A (LTT negative T1-T3, n = 48), group B (LTT positive T1-T3, n = 7), group C (developing positive LTT at T2, n = 5). A highly significant elevation of IL-1α, IL1ß, TNF-α in patients of group C (p = 0.0001) and a significant elevation of CD4+ cells in patients of group B (p = 0.005) was shown.

CONCLUSION

Our data show that following allogeneic bone grafting, local and systemic immunological reactions can be detected in some patients. These findings were statistically significant for the timepoint T3 between the tested materials as well as for the groups B and C correlated with group A for both tested materials. Therefore, the null hypotheses were rejected. A preoperative compatibility test for allogeneic materials in order to improve patient safety and the predictability of these materials would be desirable.

TRIAL REGISTRATION

Ethical commission of the Ärztekammer Hamburg, Germany (PV5211) as well as by the German Registry of Clinical Studies (DRKS00013010) on 30/07/2018 ( http://apps.who.int/trialsearch/ ).

Bioresorbable Chitosan-Based Bone Regeneration Scaffold Using Various Bioceramics and the Alteration of Photoinitiator Concentration in an Extended UV Photocrosslinking Reaction

Bone tissue engineering (BTE) is an ongoing field of research based on clinical needs to treat delayed and non-union long bone fractures. An ideal tissue engineering scaffold should have a biodegradability property matching the rate of new bone turnover, be non-toxic, have good mechanical properties, and mimic the natural extracellular matrix to induce bone regeneration. In this study, biodegradable chitosan (CS) scaffolds were prepared with combinations of bioactive ceramics, namely hydroxyapatite (HAp), tricalcium phosphate-α (TCP- α), and fluorapatite (FAp), with a fixed concentration of benzophenone photoinitiator (50 µL of 0.1% (w/v)) and crosslinked using a UV curing system. The efficacy of the one-step crosslinking reaction was assessed using swelling and compression testing, SEM and FTIR analysis, and biodegradation studies in simulated body fluid. Results indicate that the scaffolds had comparable mechanical properties, which were: 13.69 ± 1.06 (CS/HAp), 12.82 ± 4.10 (CS/TCP-α), 13.87 ± 2.9 (CS/HAp/TCP-α), and 15.55 ± 0.56 (CS/FAp). Consequently, various benzophenone concentrations were added to CS/HAp formulations to determine their effect on the degradation rate. Based on the mechanical properties and degradation profile of CS/HAp, it was found that 5 µL of 0.1% (w/v) benzophenone resulted in the highest degradation rate at eight weeks (54.48% degraded), while maintaining compressive strength between (4.04 ± 1.49 to 10.17 ± 4.78 MPa) during degradation testing. These results indicate that incorporating bioceramics with a suitable photoinitiator concentration can tailor the biodegradability and load-bearing capacity of the scaffolds.

Tooth as graft material: Histologic study

Background

An effective regenerative protocol is key to reestablish and maintain the hard and soft tissue dimensions over time. The choice of the graft material and its properties also could have an impact on the results. To prevent alveolar ridge dimensional changes, since numerous graft materials have been suggested and in the past years, a growing interest in teeth material has been observed as a valuable alternative to synthetic biomaterials.

Aim

The aim of the study was to explore the histomorphometric outcomes of tooth derivative materials as used as bone substitute material in socket preservation procedure.

Methods

After alveolar socket preservation (ASP) procedures using autologous demineralized tooth as graft material prepared by means of an innovative device, was evaluated. A total of 101 histological samples, from 96 subjects, were analyzed by evaluating the total amount of bone (BV), residual tooth material (residual graft, TT), and vital bone (VB). The section from each sample was then split in nine subsections, resulting in 909 subsections, to allow statistical comparison between the different areas.

Results

It was not noticed a statistically significant difference between maxillary and mandibular sites, being the amount of VB in upper jaw sites 37.9 ± 21.9% and 38.0 ± 22.0% in lower jaw sites and the amount of TT was 7.7 ± 12.2% in maxilla and 7.0 ± 11.1% in mandibles. None of the other considered parameters, including defect type and section position, were statistically correlated to the results of the histomorphometric analysis.

Conclusions

ASP procedure using demineralized autologous tooth‐derived biomaterial may be a predictable procedure to produce new vital bone potentially capable to support dental implant rehabilitation.

An Extrudable Partially Demineralized Allogeneic Bone Paste Exhibits a Similar Bone Healing Capacity as the "Gold Standard" Bone Graft

Autologous bone grafts (BGs) remain the reference grafting technique in various clinical contexts of bone grafting procedures despite their numerous peri- and post-operative limitations. The use of allogeneic bone is a viable option for overcoming these limitations, as it is reliable and it has been widely utilized in various forms for decades. However, the lack of versatility of conventional allogeneic BGs (e.g., blocks, powders) limits their potential for use with irregular or hard-to-reach bone defects. In this context, a ready- and easy-to-use partially demineralized allogeneic BG in a paste form has been developed, with the aim of facilitating such bone grafting procedures. The regenerative properties of this bone paste (BP) was assessed and compared to that of a syngeneic BG in a pre-clinical model of intramembranous bone healing in critical size defects in rat calvaria. The microcomputed tridimensional quantifications and the histological observations at 7 weeks after the implantation revealed that the in vivo bone regeneration of critical-size defects (CSDs) filled with the BP was similar to syngeneic bone grafts (BGs). Thus, this ready-to-use, injectable, and moldable partially demineralized allogeneic BP, displaying equivalent bone healing capacity than the “gold standard,” may be of particular clinical relevance in the context of oral and maxillofacial bone reconstructions.

A new approach for better anterior esthetic using platelet-rich fibrin as sole graft material combined with ovate design dental bridge

Alveolar ridge deficiency is considered a major esthetic limitation, especially in the maxillary anterior region. Several approaches have been developed to enhance and increase the soft-tissue volume. Among those approaches are connective tissue grafts, platelet-rich fibrin (PRF) membrane and implying the guided bone regeneration concept. The PRF grafting technique was employed in this clinical case to improve and enhance the anterior esthetic without the need for the bone graft and augmentation. This article describes the use of PRF as a sole grafting material for both socket and soft-tissue augmentation for a 23-year-old male, who had an accident 8 years ago while he was playing a basketball, which caused his upper front teeth to be intruded and discolored. The upper left central tooth suffered a major external root resorption; hence, it was extracted. PRF was prepared and packed in and extruded out of the socket. This was combined with ovate design provisional bridge. Ten days, 1 month, 3 months, and 6 months postoperative review showed a significantly well-progressed healing. According to the encouraging result obtained in this clinical case in regard to tissue healing and esthetic, the PRF can be a potential sole graft material for small anterior deficient areas. This may reduce the need of bone augmentation and graft in such selected cases.

Biomechanical Behavior of an Implant System Using Polyether Ether Ketone Bar: Finite Element Analysis

Aim and Objectives:

This study assessed, through finite element analysis, the biomechanical behavior of an implant system using the All-on-Four^® technique with nickel–chromium (M1) and polyether ether ketone (PEEK) bars (M2).

Materials and Methods:

Implants and components were represented in three-dimensional (3D) geometric models and submitted to three types of load: axial, oblique, and load on all teeth. The 3D models were exported to a computer-aided design-like software such as Solidworks 2016 (Dassault Systemes, Solidworks Corps, USA) for editing and Nonuniform Rational Basis Splines parametrization.

Results:

Data were analyzed according to system's areas of action: peri-implant bone, implant, intermediates, intermediates’ screws, prostheses’ screws, and bars. Largest peak stress was shown in M2.

Conclusion:

PEEK is a promising material for use in dentistry; however, further studies are necessary to evaluate its performance.

Comparative study to evaluate bone loss during osteotomy using standard drill, bone trephine, and alveolar expanders for implant placement

Statement of Problem:

Various osteotomy modalities seem to have an impact on the primary and secondary stability of the dental implant. The available literature lacks the comparison of various available osteotomy modalities used for the dental implant placement and its effects on the initial surgical bone removal.

Purpose:

The purpose of this study is to compare and evaluate the osteotomy sites created using standard drill, bone trephine, and alveolar expanders for dental implant surgery.

Materials and Methods:

The study was done on ten goat hemimandibles. Three osteotomy sites were prepared at the inferior border of the mandible using standard drill, trephine, and alveolar expander in each hemimandibles and the sites were subjected to cone-beam computed tomography (CBCT). The CBCT images obtained were compared for the amount of cortical bone and bone marrow loss at osteotomy sites in different techniques.

Results:

The mean and standard deviation of loss of cortical bone with standard drills, trephines, and alveolar expanders was 3.62 ± 4.216 × 10⁻², 3.6 ± 4.681 × 10⁻¹⁶ and 3.15 ± 7.071 × 10⁻². At the middle-third region, the loss of marrow bone was 3.38 ± 7.88 × 10⁻², 2.15 ± 8.498 × 10⁻² and 0.03 ± 9.487 × 10⁻², and at lower third region, it was 2.3 ± 4.714 × 10⁻², 0.02 ± 6.325 × 10⁻², and 0.0, respectively.

Conclusion:

CBCT images showed minimum bone loss with the use of alveolar expander which may be due to the lateral bone condensation rather the removal of the marrow. Trephine showed less marrow removal in comparison to the standard drill used for dental implant surgery.