Bone Dental Implants Research Articles

Biomechanical evaluation of customized root implants in alveolar bone: A comparative study with traditional implants and natural teeth.

To compare and evaluate density changes in alveolar bones and biomechanical responses including stress/strain distributions around customized root implants (CRIs), traditional implants, and natural teeth. A three-dimensional finite element model of the maxillary dentition defect, CRI models, traditional restored implant models, and natural teeth with periodontal tissue models were established. The chewing load of the central incisor, the traditional implant, and the CRI was 100N, and the load direction was inclined by 11° in the sagittal plane. According to the bone remodeling numerical algorithm, the bone mineral density and distribution were calculated and predicted. In addition, animal experiments were performed to verify the feasibility of the implant design. The results of the simulation calculations were compared with animal experimental data in vivo to verify their validity. No significant differences in bone mineral density and stress/strain distribution were found between the CRI and traditional implant models. The animal experimental results (X-ray images and histological staining) were consistent with the numerical simulated results. CRIs were more similar to traditional implants than to natural teeth in terms of biomechanical and biological evaluation. Considering the convenience of clinical application, this biomechanical evaluation provides basic theoretical support for further applications of CRI.

Biomechanical performance of Ti-PEEK dental implants in bone: An in-silico analysis

Stress-shielding is caused by a significant mismatch in stiffness between bone tissue and Ti alloy dental implants. Therefore, in this study, a Ti-PEEK composite implant was examined and compared with conventional titanium, to determine the behavior of the host bone. Twelve 3D finite element models were modeled with two conditions of marginal cortical bone (with and without marginal bone loss). Six implant designs were constructed. Implant (A) was made with a conventional design (dense titanium), implants (B), (C) and (D) are designed with Ti-PEEK composite (outer layer made of PEEK and inner structures made of Ti with hexagonal, cylindrical, and cross shapes for implants (B), (C) and (D), respectively), the implant (E) is designed with Ti at the upper half section and PEEK at the bottom half section, and the implant (F) is designed with PEEK at the upper half section and Ti at the bottom half section. An axial load of 200 N was applied to the buccal cusp and central fossa of the occlusal surface. The displacements, stress, and equivalent strain were analyzed at the level of bone tissue. The mechanostat of Frost was used to determine the behavior of the cancellous bone under these biomechanical conditions. Results showed that strains were greater in cancellous bone with marginal bone loss than in healthy bone (w/o MBL). When compared to implants (B)-(F), conventional implant (A) did not produce as much strain. Thus, results and analyses suggest that the Ti-PEEK implants outperform compared with the implant (A) in the case of no marginal bone loss. However, the implants (A) and (E) perform equally in terms of bone loss.

Osseointegration of Sandblasted and Acid-Etched Implant Surfaces. A Histological and Histomorphometric Study in the Rabbit.

Titanium surface is an important factor in achieving osseointegration during the early wound healing of dental implants in alveolar bone. The purpose of this study was to evaluate sandblasted-etched surface implants to investigate the osseointegration. In the present study, we used two different types of sandblasted-etched surface implants, an SLA™ surface and a Nanoblast Plus™ surface. Roughness and chemical composition were evaluated by a white light interferometer microscope and X-ray photoelectron spectroscopy, respectively. The SLA™ surface exhibited the higher values (Ra 3.05 μm) of rugosity compared to the Nanoblast Plus™ surface (Ra 1.78 μm). Both types of implants were inserted in the femoral condyles of ten New Zealand white rabbits. After 12 weeks, histological and histomorphometric analysis was performed. All the implants were osseointegrated and no signs of infection were observed. Histomorphometric analysis revealed that the bone–implant contact % (BIC) ratio was similar around the SLA™ implants (63.74 ± 13.61) than around the Nanoblast Plus™ implants (62.83 ± 9.91). Both implant surfaces demonstrated a favorable bone response, confirming the relevance of the sandblasted-etched surface on implant osseointegration.

When is buccal bone mandatory?

The circumferential anchorage of dental implants in bone is an important prerequisites for excellent long-term outcomes. Clinical reality shows that bone is often missing on the buccal aspect of potential implant sites due to bone alterations post extraction. Therefore, bone augmentation is often needed on the buccal aspect, which has 3 goals: (a) provide osseointegration of the inserted implant to withstand the functional loading of this implant over time, (b) provide a sufficient bony contour to support the facial peri-implant soft tissues for esthetic reasons, and (c) avoid the exposure of the micro-rough implant surface to the peri-implant sulcus. The lecture will address these points.

Site-Specific Variations in Bone Mineral Density under Systemic Conditions Inducing Osteoporosis in Minipigs.

Osteoporosis is a systemic bone disease with an increasing prevalence in the elderly population. There is conflicting opinion about whether osteoporosis affects the alveolar bone of the jaws and whether it poses a risk to the osseointegration of dental implants. The aim of the present study was to evaluate the effects of systemic glucocorticoid administration on the jaw bone density of minipigs. Thirty-seven adult female minipigs were randomly divided into two groups. Quantitative computed tomography (QCT) was used to assess bone mineral density BMD of the lumbar spine as well as the mandible and maxilla, and blood was drawn. One group of minipigs initially received 1.0 mg prednisolone per kg body weight daily for 2 months. The dose was tapered to 0.5 mg per kg body weight per day thereafter. The animals in the other group served as controls and received placebo. QCT and blood analysis were repeated after 6 and 9 months. BMD was compared between the two groups by measuring Hounsfield units, and serum levels of several bone metabolic markers were also assessed. A decrease in BMD was observed in the jaws from baseline to 9 months. This was more pronounced in the prednisolone group. Statistically significant differences were reached for the mandible (p < 0.001) and the maxilla (p < 0.001). The administration of glucocorticoids reduced the BMD in the jaws of minipigs. The described model shows promise in the evaluation of osseointegration of dental implants in bone that is compromised by osteoporosis.

Modeling and simulation of platelet reaction and diffusion towards an electro-stimulating dental implant.

Electrical stimulation (ES) has been used clinically to promote bone ingrowth on implant surface. The osseointegration of biomaterials in bone requires complex biological interactions between different bone cells species. At the early stages of bone healing, it is reported in literature that platelets play an important role in stimulating stem cells, osteogenic cells and osteoblasts. This work studies the coupling of the reaction-diffusion model of platelets with external ES. For this, we introduce a mathematical model framework consisting of a system of coupled partial differential equations. Platelets' migration and interaction within a realistic 3D model adapted from an electro-stimulating dental implant is studied. DC voltage of 3.1 V is applied at the electrodes. The electric field distribution around the electro-stimulating dental implant is simulated. High concentration of platelets around the implant surface is achieved after one day of healing. Based on these results, it is shown that osseointegration of dental implants in bone could be enhanced and accelerated by means of ES.

Automated 3D–2D registration of X-ray microcomputed tomography with histological sections for dental implants in bone using chamfer matching and simulated annealing

We propose a novel 3D–2D registration approach for micro-computed tomography (μCT) and histology (HI), constructed for dental implant biopsies, that finds the position and normal vector of the oblique slice from μCT that corresponds to HI. During image pre-processing, the implants and the bone tissue are segmented using a combination of thresholding, morphological filters and component labeling. After this, chamfer matching is employed to register the implant edges and fine registration of the bone tissues is achieved using simulated annealing.The method was tested on n=10 biopsies, obtained at 20 weeks after non-submerged healing in the canine mandible. The specimens were scanned with μCT 100 and processed for hard tissue sectioning. After registration, we assessed the agreement of bone to implant contact (BIC) using automated and manual measurements. Statistical analysis was conducted to test the agreement of the BIC measurements in the registered samples.Registration was successful for all specimens and agreement of the respective binary images was high (median: 0.90, 1.–3. Qu.: 0.89–0.91). Direct comparison of BIC yielded that automated (median 0.82, 1.–3. Qu.: 0.75–0.85) and manual (median 0.61, 1.–3. Qu.: 0.52–0.67) measures from μCT were significant positively correlated with HI (median 0.65, 1.–3. Qu.: 0.59–0.72) between μCT and HI groups (manual: R2=0.87, automated: R2=0.75, p<0.001).The results show that this method yields promising results and that μCT may become a valid alternative to assess osseointegration in three dimensions.

Partially Biodegradable Distraction Implant to Replace Conventional Implants in Alveolar Bone of Insufficient Height: A Preliminary Study in Dogs.

Dental implants have been widely used in the last few decades. However, patients with insufficient bone height need reconstructive surgeries before implant insertion. The distraction implant (DI) has been invented to simplify the treatment procedure, but the shortcomings of DIs have limited their clinical use. We incorporated biodegradable polyester into a novel DI called the partially biodegradable distraction implant (PBDI). The purpose of this study was to assess the radiological, histological, and biomechanical properties of the PBDI in animal models. PBDIs were manufactured and inserted into the atrophied mandibles of nine dogs. Box-shaped alveolar bones were segmented and distracted. The dogs were randomly divided into three groups that were sacrificed 1, 2, and 3 months after the implant insertion. Actual augmentation height (AAH) of the bone segments was measured to evaluate the effect of distraction. X-ray examination and micro-CT reconstruction and analysis were used to evaluate the regenerated bone in the distraction gap and bone around the functional element. Histological sections were used to evaluate the osseointegration and absorption of the PBDI. Fatigue tests were used to evaluate the biomechanical properties of the PBDI. Little change was found in AAH among the three groups. X-ray examination and micro-CT reconstruction showed good growth of regenerated bone in the distraction gap. Alveolar bone volume around the functional element increased steadily. No obvious bone absorption occurred in the alveolar crest around PBDI. Three months after distraction, the functional element achieved osseointegration, and the support element began to be absorbed. All PBDIs survived the fatigue test. The PBDI is a novel and reliable dental implant. It becomes a conventional implant after the absorption of the support element and the removal of the distraction screw. It is a promising replacement for conventional implants in patients with insufficient alveolar bone height.

Implants in bone: Part I. A current overview about tissue response, surface modifications and future perspectives

The aim of study paper is to present an overview of osseointegration of dental implants, focusing on tissue response, surface modifications and future perspective. Great progress has been made over the decades in the understanding of osseous peri-implant healing of dental implants, leading to the development of new implant materials and surfaces. However, failures and losses of implants are an indicator that there is room for improvement. Of particular importance is the understanding of the biological interaction between the implant and its surrounding bone. The survival rates of dental implants in bone of over 90% after 10years show that they are an effective and well-established therapy option. However, new implant materials and surface modifications may be able to improve osseointegration of medical implants especially when the wound healing is compromised. Advanced techniques of evaluation are necessary to understand and validate osseointegration in these cases. An overview regarding the current state of the art in experimental evaluation of osseointegration of implants and implant material modifications will be given in Part II.

Evaluation of the Tissue Response to MTA and MBPC: Microscopic Analysis of Implants in Alveolar Bone of Rats

The aim of this study was to evaluate and compare the quantitative and qualitative inflammatory responses and bone formation potential after implantation of polyethylene tubes filled with a new calcium hydroxide containing sealer (MBPc) and ProRoot mineral trioxide aggregate (MTA). There were 48 Wistar rats divided in three groups: Group I (control group) empty polyethylene tubes were implanted in the extraction site; group II and III, polyethylene tubes were implanted filled with ProRoot mineral trioxide aggregate (MTA) and MBPc, respectively. At 7, 15, and 30 days after tube implantation, the animals were killed, the hemi-maxillas were removed and prepared to light microscopic analyses. The scores obtained were submitted to Kruskal-Wallis statistical test (p < 0.05). Significant differences between the materials were not observed. The results showed that both materials had similar biological response.

Analysis of Failed Commercially Pure Titanium Dental Implants: A Scanning Electron Microscopy and Energy‐Dispersive Spectrometer X‐Ray Study

The failure of osseointegration in oral rehabilitation has gained importance in current literature and in clinical practice. The integration of titanium dental implants in alveolar bone has been partly ascribed to the biocompatibility of the implant surface oxide layer. The aim of this investigation was to analyze the surface topography and composition of failed titanium dental implants in order to determine possible causes of failure. Twenty-one commercially pure titanium (cpTi) implants were retrieved from 16 patients (mean age of 50.33 +/- 11.81 years). Fourteen implants were retrieved before loading (early failures), six after loading (late failures), and one because of mandibular canal damage. The failure criterion was lack of osseointegration characterized as dental implant mobility. Two unused implants were used as a control group. All implant surfaces were examined by scanning electron microscopy (SEM) and energy-dispersive spectrometer x-ray (EDS) to element analysis. Evaluations were performed on several locations of the same implant. SEM showed that the surface of all retrieved implants consisted of different degrees of organic residues, appearing mainly as dark stains. The surface topography presented as grooves and ridges along the machined surface similar to control group. Overall, foreign elements such as carbon, oxygen, sodium, calcium, silicon, and aluminum were detected in failed implants. The implants from control group presented no macroscopic contamination and clear signs of titanium. These preliminary results do not suggest any material-related cause for implant failures, although different element composition was assessed between failed implants and control implants.

Impulse response of a dental implant in bone by numerical analysis

The osseointegration process of titanium dental implants in bone has been simulated previously using natural frequency and impulse excitation. However, the impulse strength was arbitrarily chosen and may not have yielded the correct frequencies and displacements to be compared with those measured in a clinical situation. In this work the range of impulse excitation strengths applied to a dental implant osseointegrated in bone and the corresponding response have been examined using the finite element method. Both conditions of a dental pin only and a dental pin with attached cantilever integrated in the mandible have been examined. The dynamic analysis indicated that the frequency and displacement responses are indeed sensitive to impulse duration and direction but independent of impulse load. The analysis summarizes the proper impulse excitation values for a correct interpretation of clinically measured frequency response data.