New Trends in Bioengineering in Osseointegration and Dental Implants

The aim of this study was to evaluate the effect of implant surface treatment with carboxyethylphosphonic acid and fibroblast growth factor 2 on the bone–implant interface during the osseointegration period in vivo using an animal model. The present research was carried out in six minipigs, in whose left tibia implants were inserted as follows: eight implants with a standard surface treatment, for the control group, and eight implants with a surface treatment of carboxyethylphosphonic acid and immobilization of FGF-2, for the test group. At 4 weeks after the insertion of the implants, the animals were sacrificed for the histomorphometric analysis of the samples. The means of the results for the implant–bone contact variable (BIC) were 46.39 ± 17.49% for the test group and 34.00 ± 9.92% for the control group; the difference was not statistically significant. For the corrected implant–bone contact variable (BICc), the mean value of the test group was 60.48 ± 18.11%, and that for the control group, 43.08 ± 10.77%; the difference was statistically significant (p-value = 0.035). The new bone formation (BV/TV) showed average results of 27.28 ± 3.88% for the test group and 26.63 ± 7.90% for the control group, meaning that the differences were not statistically significant (p-value = 0.839). Regarding the bone density at the interthread level (BAI/TA), the mean value of the test group was 32.27 ± 6.70%, and that of the control group was 32.91 ± 7.76%, with a p-value of 0.863, while for the peri-implant density (BAP/TA), the mean value of the test group was 44.96 ± 7.55%, and that for the control group was 44.80 ± 8.68%, without a significant difference between the groups. The current research only found a significant difference for the bone–implant contact at the cortical level; therefore, it could be considered that FGF-2 acts on the mineralization of bone tissue. The application of carboxyethylphosphonic acid on the surface of implants can be considered a promising alternative as a biomimetic coating for the immobilization of FGF-2. Despite no differences in the new bone formation around the implants or in the interthread or peri-implant bone density being detected, the biofunctionalization of the implant surface with FGF-2 accelerates the mineralization of the bone–implant interface at the cortical level, thereby reducing the osseointegration period. Full article

Due to the rising demand for zirconia (Zr) based implant systems, it is important to understand the impact of Zr and titanium (Ti) implants and particularly their topography on soft tissue healing. As human gingival fibroblasts (hGFs) are the predominant cells in peri-implant soft tissue, we focused on examining the effect of implant material and surface roughness on hGFs’ initial attachment, growth and the expression of proteins involved in the focal adhesion. hGFs isolated from eight healthy donors were cultured on the following surfaces: smooth titanium machined surface (TiM), smooth zirconia machined surface (ZrM), moderately rough titanium surface (SLA), or moderately rough zirconia surface (ZLA) for up to 14 days. The initial attachment of hGFs was evaluated by scanning electron microscopy. Cell proliferation/viability was assessed by cell counting kit 8. Focal adhesion and cytoskeleton were visualized by a focal adhesion staining kit. The gene expression of focal adhesion kinase (FAK), α-smooth muscle actin (α-SMA), and integrin subunits ITG-β1, ITG-β4, ITG-α4, ITG-α5, ITG-α6, was evaluated by qPCR. Cell proliferation/viability was slightly decreased by moderately rough surfaces, whereas no effect of surface material was observed. Cell morphology was strikingly different between differently treated surfaces: on machined surfaces, cells had elongated morphology and were attached along the grooves, whereas on moderately rough surfaces, cells were randomly attached. Surface roughness had a more pronounced effect on the gene expression compared to the surface material. The expression of FAK, α-SMA, ITG-β4, ITG-α5, and ITG-α6 was enhanced by moderately rough surfaces compared to smooth surfaces. Within the limitations of this in vitro study, it can be concluded that the behavior of primary hGFs is primarily affected by surface structure, whereas no apparent advantage of Zr over Ti could be observed. Full article

Objectives: To determine the effect of mechanical loading of bone on the stability and histomorphometric variables of the osseointegration of dental implants using an experimental test in an animal model. Materials and Methods: A total of 4 human implants were placed in both tibiae of 10 New Zealand rabbits (n = 40). A 6-week osseointegration was considered, and the rabbits were randomly assigned to two groups: Group A (Test group) included 5 rabbits that ran on a treadmill for 20 min daily during the osseointegration period; Group B (Controls) included the other 5 that were housed conventionally. The monitored variables were related to the primary and secondary stability of the dental implants (implant stability quotient—ISQ), vertical bone growth, bone to implant contact (BIC), area of regenerated bone and the percentage of immature matrix. Results: The results of the study show a greater vertical bone growth (Group A 1.26 ± 0.48 mm, Group B 0.32 ± 0.47 mm, p < 0.001), higher ISQ values (Group A 11.25 ± 6.10 ISQ, 15.73%; Group B 5.80 ± 5.97 ISQ, 7.99%, p = 0.006) and a higher BIC (Group A 19.37%, Group B 23.60%, p = 0.0058) for implants in the test group, with statistically significant differences. A higher percentage of immature bone matrix was observed for implants in the control group (20.68 ± 9.53) than those in the test group (15.38 ± 8.84) (p = 0.108). A larger area of regenerated bone was also observed for the test implants (Group A 280.50 ± 125.40 mm², Group B 228.00 ± 141.40 mm²), but it was not statistically significant (p = 0.121). Conclusions: The mechanical loading of bone improves the stability and the histomorphometric variables of the osseointegration of dental implants. Full article

The present in vitro study evaluated a new drill design to improve the temperature control during the osteotomies for dental implant installation, comparing with two drill designs that use conventional external irrigation. Three blocks of synthetic cortical bone were used for osteotomy procedures. Three groups were created: control group 1 (Con1), where a conical multiple drill system with a conventional external irrigation system was used; control group 2 (Con2), where a single bur with a conventional external irrigation system was used; and, test group (Test), where the new single bur (turbo drill) with a new irrigation system was used. Twenty osteotomies were made without irrigation and with intense irrigation, for each group. A thermocouple was used to measure the temperature produced during the osteotomies. The measured temperature were: 28.9 ± 1.68 °C for group Con1; 27.5 ± 1.32 °C for group Con2; 26.3 ± 1.28 °C for group Test. Whereas, the measured temperatures with irrigation were: 23.1 ± 1.27 °C for group Con1; 21.7 ± 1.36 °C for group Con2; 19.4 ± 1.29 °C for group Test. The single drill with a new design for improving the irrigation and temperature control, in comparison with the drill designs with conventional external irrigation. Full article

The aim of this study was to assess the long-term clinical behavior of straight implants in comparison with intentionally tilted dental implants (ITDI) supporting fixed restorations in partial or total edentulous arches, analyzing implant survival and success rates, complications, and marginal bone loss (MBL) after >5 years of function. An electronic search was conducted in five electronic databases (MEDLINE/Pubmed, Embase, Web of Science, Scopus, and Cochrane Central Register of Controlled Trials) supplemented by a manual search. The electronic and manual search identified 1853 articles, of which 8 articles were selected for analysis. Out of a total of 3987 dental implants, 2036 were axial dental implants and 1951 tilted. Similar results were found in implant survival or overall implant success rates. Moreover, no statistically significant differences were found in MBL (p = 0.369; MD 0.116 mm (−0.137; 0.369) 95% CI) The prosthodontic/biological complications reported in the articles were very diverse and irregularly distributed. This systematic review suggests that there is no difference between tilted compared with straight dental implants in the medium-long term (>5 years). However, further research is needed to generate long-term data and confirm the present review’s findings. Full article

This systematic review and meta-analysis set out to assess the clinical behavior of mandibular implant-supported fixed complete dental prostheses (ISFCDP) on three dental implants by analyzing implant and prosthetic survival rates, marginal bone loss, biological/technical complications, and patient-reported outcomes. The review was conducted according to PRISMA guidelines. Electronic searches were conducted in the Medline (PubMed), Web of Science, and Cochrane databases, complimented by a manual search in specialist journals for relevant articles published up to February 2021. The Newcastle-Ottawa Quality Assessment Scale tool was used to assess the quality of evidence in the studies reviewed. The study included 13 articles with 728 patients treated with 2184 implants. A mean implant survival rate of 95.9% (95% CI: 94.6–97.3%) and a prosthetic survival rate of 97.0% (95% CI: 95.7–98.3%) were obtained over 1–6-year follow-up periods. Mandibular implant-supported fixed complete dental prostheses on three dental implants would appear to be a viable option for restoring the edentulous mandible in comparison with mandibular ISFCDP on more than three implants. Further comparative studies are needed, with adequate protocols, as well as sufficient sample sizes and follow-up periods to confirm these findings. Full article

Chitosan is a natural polysaccharide extracted from the shells of crustaceans that has been proposed as a scaffold in tissue engineering. Certain studies have proven a greater osseointegration of titanium surfaces that are functionalized with chitosan. The MEDLINE, CENTRAL, PubMed, and Web of Science databases were electronically searched for in vivo studies. Seven studies met the inclusion criteria. Animal models, implant site, chitosan incorporation methods, and methods of analysis were emphasized. The selected studies were individually discussed regarding the coatings, osseointegration potential, and suitability of the experimental models used, analyzing their limitations. We concluded that chitosan-biofunctionalized titanium surfaces have greater osseointegration capacity that uncoated control titanium alloys. Full article

The purpose of this scoping review was to describe the current state of knowledge and understanding of allergies to titanium dental implants. A scoping review was conducted following the Prisma Extension for Scoping Reviews checklist. An electronic search was performed in five databases complemented by manual and grey literature searches. Fifty-two relevant papers were included for final review. Titanium particles can be released from the surfaces of dental implants in a process called tribocorrosion, which may contribute to bone loss due to inflammatory reaction. Diverse mechanisms have been described that may trigger allergy to titanium, as well as the clinical signs that manifest as the allergy develops. Allergies to titanium are uncommon but represent a real possibility that should not be overlooked in patients requiring prosthodontic rehabilitation with dental implants. Allergy can trigger a range of symptoms. Patients who have already been diagnosed with allergies to other metals will be more predisposed to suffering an allergy to titanium. Further investigation is needed in order to measure the true scope of these allergies. Full article

Mechanical complications in implant-supported fixed dental prostheses are often related to implant and prosthetic design. Although the current ISO 14801 provides a framework for the evaluation of dental implant mechanical reliability, strict adherence to it may be difficult to achieve due to the large number of test specimens which it requires as well as the fact that it does not offer any probabilistic reference for determining the endurance limit. In order to address these issues, a new software program called ProFatigue is presented as a potentially powerful tool to optimize fatigue testing of implant-supported prostheses. The present work provides a brief description of some concepts such as load, fatigue and stress-number of cycles to failure curves (S-N curves), before subsequently describing the current regulatory situation. After analyzing the two most recent versions of the ISO recommendation (from 2008 and 2016), some limitations inherent to the experimental methods which they propose are highlighted. Finally, the main advantages and instructions for the correct implementation of the ProFatigue free software are given. This software will contribute to improving the performance of fatigue testing in a more accurate and optimized way, helping researchers to gain a better understanding of the behavior of dental implants in this type of mechanical test. Full article

Bone plays an important role in dental implant treatment success. The goal of this literature review is to analyze the influence of bone definition and finite element parameters on stress in dental implants and bone in numerical studies. A search was conducted of Pubmed, Science Direct and LILACS, and two independent reviewers performed the data extraction. The quality of the selected studies was assessed using the Cochrane Handbook tool for clinical trials. Seventeen studies were included. Titanium was the most commonly-used material in dental implants. The magnitude of the applied loads varied from 15 to 300 N with a mean of 182 N. Complete osseointegration was the most common boundary condition. Evidence from this review suggests that bone is commonly defined as an isotropic material, despite being an anisotropic tissue, and that it is analyzed as a ductile material, instead of as a fragile material. In addition, and in view of the data analyzed in this review, it can be concluded that there is no standardization for conducting finite element studies in the field of dentistry. Convergence criteria are only detailed in two of the studies included in this review, although they are a key factor in obtaining accurate results in numerical studies. It is therefore necessary to implement a methodology that indicates which parameters a numerical simulation must include, as well as how the results should be analyzed. Full article