Intra-osseous anchorage of dental prostheses. I. Experimental studies

Effects of Rigid and Nonrigid Connections between the Miniscrew and Anchorage Tooth on Dynamics, Efficacy, and Adverse Effects of Maxillary Second Molar Protraction: A Finite Element Analysis

Introduction

Direct, rigid indirect, and nonrigid indirect absolute anchorages using temporary anchorage devices (TADs, mini-implants/miniscrews) can provide promising opportunities for challenging, yet common, orthodontic tooth movements such as molar protraction. Rigid rectangular wire and ligature wire are the most common methods of attaching a tooth to a miniscrew in indirect anchorages. We aimed to provide a comparison of the rigidity of the connecting wire in terms of stress on the miniscrew, the anchorage loss, and the risk of root resorption using finite element analysis (FEA).

Methods

The maxillary right second molar was protracted into the proximal space at a 150 g load (1) using direct absolute anchorage with a tapered miniscrew implanted between the premolar roots and using indirect absolute anchorage with the second premolar reinforced by the miniscrew through (2) a rigid stainless steel (SS) wire or (3) a nonrigid SS ligature wire (4) at different elastic moduli. Stresses and displacements of 4 models' elements were measured. The risk of external root resorption was evaluated.

Results

Connecting the tooth to the miniscrew using rigid full-size wire (model 2) compared to ligature (model 3) can give better control of the anchorage (using the ligature wire, the anchorage loss is 1.5 times larger than the rectangular wire) and may reduce the risk of root resorption of the anchorage unit. However, the risk of miniscrew failure increases with a rigid connection, although it is still lower than with direct anchorage. The miniscrew stress when using a ligature is approximately 30% of the rigid model using the rectangular wire. The miniscrew stress using the rectangular wire is approximately 82.4% of the miniscrew stress in the direct model. Parametric analysis shows that the higher the elastic modulus of the miniscrew-tooth connecting wire in the indirect anchorage, the less the anchorage loss/palatal rotation of the premolars/and the risk of root resorption of the anchorage teeth and instead the stress on the miniscrew increases.

Conclusions

Direct anchorage (followed by rigid indirect anchorage but not nonrigid) might be recommended when the premolars should not be moved or premolar root resorption is a concern. Miniscrew loosening risk might be the highest in direct anchorage and lowest in nonrigid indirect anchorage (which might be recommended for poor bone densities).

Stainless steel vs. titanium miniscrew implants: Evaluation of stability during retraction of maxillary and mandibular anterior teeth

OBJECTIVES

This study was aimed to compare the stability of stainless steel and titanium miniscrew implants of the same diameter and length during en masse retraction of maxillary and mandibular anterior teeth.

MATERIALS AND METHODS

Forty miniscrew implants (1.3 mm diameter and 8 mm length) were placed in 10 patients (20 titanium and 20 stainless steel). Stability was checked at insertion (T0), at one month (T1), and at sixth months (T2) and the amount of retraction was recorded in millimeters.

RESULTS

Titanium and stainless steel implants were equally stable at the time of insertion. At T1, three titanium miniscrew implants showed grade 2 mobility, whereas seven stainless steel miniscrew implants showed grade 2 mobility. For T2, none of the titanium miniscrew implants had grade 2 mobility while four stainless steel miniscrew implants resulted in grade 2 mobility. Both had an equal frequency of grade 3 and grade 4 mobility. However, the difference in the stability was not statistically significant. No statistical significance was found when the amount of retraction achieved by titanium and stainless steel miniscrew implants was compared between the maxillary and mandibular arches.

CONCLUSION

Both titanium and stainless steel miniscrew implants provide good anchorage and remain stable during en masse retraction of maxillary and mandibular anterior teeth. Thus, both miniscrews are clinically effective.

Retained Dental Implant in the Maxillary Sinus

Implant dentistry has become a popularized means of replacing damaged or missing teeth. Although it has become common practice, there are accounts of implants displacing into surrounding structures, commonly the maxillary sinus. We present the case of a 54-year-old man who presented with chronic left sided pain and pressure found to be secondary to a displaced implant obstructing the left maxillary outflow sinus tract. A systematic review was conducted to assess the current management and treatment options for dental implants displaced into the maxillary sinus. Functional endoscopic sinus surgery (FESS) and the lateral window approach were both found to be safe techniques with minimal postoperative complications.

BMP Gene-Immobilization to Dental Implants Enhances Bone Regeneration

For individuals who have experienced tooth loss, dental implants are an important treatment option for oral reconstruction. For these patients, alveolar bone augmentation and acceleration of osseointegration optimize implant stability. Traditional oral surgery often requires invasive procedures, which can result in prolonged treatment time and associated morbidity. It has been previously shown that chemical vapor deposition (CVD) polymerization of functionalized [2.2]paracyclophanes can be used to anchor gene encoding vectors onto biomaterial surfaces and local delivery of a bone morphogenetic protein (BMP)-encoding vector can increase alveolar bone volume and density in vivo. This study is the first to combine the use of CVD technology and BMP gene delivery on titanium for the promotion of bone regeneration and bone to implant contact in vivo. BMP-7 tethered to titanium surface enhances osteoblast cell differentiation and alkaline phosphatase activity in vitro and increases alveolar bone regeneration and % bone to implant contact similar to using high doses of exogenously applied BMP-7 in vivo. The use of this innovative gene delivery strategy on implant surfaces offers an alternative treatment option for targeted alveolar bone reconstruction.

Tamoxifen improves homeostasis in the peri-implant bone remodeling of osseointegrated titanium implants

BACKGROUND

The purpose of this preclinical study was to evaluate the influence of tamoxifen (TAM) on the peri-implant bone remodeling of osseointegrated titanium implants in ovariectomized female rats.

MATERIALS AND METHODS

Seventy-two female rats underwent bilateral ovariectomy 20 weeks before implants placement. One titanium implant was inserted in each tibia of the animals. Six weeks following the implant surgery, animals were randomly divided into two experimental groups (n = 36), which received either saline solution (SS) or tamoxifen citrate (TAM) via gavage until euthanasia. Euthanasia was performed at 30, 60, and 90 days after the first gavage. Assessments of bone to implant contact (BIC), bone ingrowth percentage (BIN), morphological description of cellular and tissue reactions, immunohistochemistry for the detection of bone morphogenetic protein 2/4 (BMP2/4), runt-related transcription factor 2 (RUNX-2), osteocalcin (OCN) and tartrate-resistant acid phosphatase (TRAP), and bone chemical composition through scanning electron microscopy with energy-dispersive x-ray spectroscopy were performed.

RESULTS

Tamoxifen group presented higher BIC, higher BIN, higher RUNX-2 and OCN, lower TRAP-positive cells/mm2 , and no differences regarding BMP-2/4 positive cells/mm2 than SS group in all periods. TAM group also showed higher Ca/P rate than SS group.

CONCLUSION

Tamoxifen enhanced the remodeling of the bone surrounding titanium implants in ovariectomized rats.

Marginal bone level change during sequential loading periods of partial edentulous rehabilitation using immediately loaded self-tapping implants: a 6.5-year retrospective study

PURPOSE

A large number of studies have suggested the practicability and predictability of immediate implant function, but few studies have reported marginal bone level changes during sequential loading periods. The purpose of this study was to evaluate the marginal bone remodeling of immediately loaded self-tapping implants both at each time point and during each loading period between two time points.

MATERIALS AND METHODS

The patients included in this retrospective study were treated with immediately loaded NobelSpeedy Replace implants between August 2008 and July 2009. Differences in the marginal bone level (MBL) at each time point and the marginal bone level change (ΔMBL) between two time points were analyzed with Bonferroni correction (P < .05).

RESULTS

Overall, 24 patients (mean age, 47.3 ± 12.8 years) with 42 immediately loaded implants and a median follow-up of 6.5 years (IQR, 67.8 months) were included. The cumulative survival rate after 10 - 12 years was 95.2%. Continuous but slow marginal bone loss was observed during long-term follow-up. MBL at both 7.5 years and 11 years was significantly lower than that at loading, 6 months, 2 years and 4 years (P < .05). No bone loss difference was found in any period before 4 years of follow up (P > .05). The loading period of 4 years to 7.5 years showed the largest ΔMBL compared to those of other time periods (P < .05).

CONCLUSION

Slight bone loss occurred continuously, and more radical changes of marginal bone can be observed during the period of 4-7.5 years. Thus, long-term effective follow-up of immediately loaded implants is needed.

Microstructure, mechanical properties and osseointegration ability of Ta-20Zr alloy used as dental implant material

The aim of this study was to evaluate the application prospect of a tantalum (Ta) and zirconium (Zr) alloy as a dental implant material. The Ta-20Zr (wt.%) alloy was prepared by powder metallurgy, and its microstructure and mechanical properties were analyzed by standard techniques. The effect of Ta-20Zr alloy on inflammation, bone remodeling and osseointegration was analyzed in rat and rabbit models by biochemical, histological and imaging tests. The Ta-20Zr alloy showed excellent mechanical compatibility with the bone tissue on account of similar elastic modulus (49.2 GPa), thereby avoiding the 'stress shielding effect'. Furthermore, Ta-20Zr alloy enhanced the inflammatory response by promoting secretion of interleukin-6 (IL-6) and IL-10, and facilitated the balance between the M1/M2 macrophage phenotypes. Finally, Ta-20Zr also showed excellent osseointegration and osteogenic ability without any systemic side effects, making it an ideal dental implant material.

A systematic review on neutrophils interactions with titanium and zirconia surfaces: Evidence from in vitro studies

Objectives

This systematic review aimed to assess in vitro studies that evaluated neutrophil interactions with different roughness levels in titanium and zirconia implant surfaces.

Material and Methods

An electronic search for literature was conducted on PubMed, Embase, Scopus, and Web of Science and a total of 14 studies were included. Neutrophil responses were assessed based on adhesion, cell number, surface coverage, cell structure, cytokine secretion, reactive oxygen species (ROS) production, neutrophil activation, receptor expression, and neutrophil extracellular traps (NETs) release. The method of assessing the risk of bias was done using the toxicological data reliability assessment tool (TOXRTOOL).

Results

Ten studies have identified a significant increase in neutrophil functions, such as surface coverage, cell adhesion, ROS production, and NETs released when interacting with rough titanium surfaces. Moreover, neutrophil interaction with rough–hydrophilic surfaces seems to produce less proinflammatory cytokines and ROS when compared to naive smooth and rough titanium surfaces. Regarding membrane receptor expression, two studies have reported that the FcγIII receptor (CD16) is responsible for initial neutrophil adhesion to hydrophilic titanium surfaces. Only one study compared neutrophil interaction with titanium alloy and zirconia toughened alumina surfaces and reported no significant differences in neutrophil cell count, activation, receptor expression, and death.

Conclusions

There are not enough studies to conclude neutrophil interactions with titanium and zirconia surfaces. However, different topographic modifications such as roughness and hydrophilicity might influence neutrophil interactions with titanium implant surfaces.

Apatite-forming ability of sandblasted and acid-etched titanium surfaces modified by ultraviolet irradiation: An in vitro study

Introduction:

Contamination of large grit sandblasting and acid-etching (SLA) with hydrocarbons make the surface hydrophobic and influence its bioactivity. Preservation in dH2O (modified SLA, modSLA) and ultraviolet (UV) irradiation were proven to be effective in decreasing hydrocarbon contamination and keeping the SLA surface hydrophilic.

Aims:

The aim of this study was to detect the in vitro bioactivity of SLA, modSLA and UV-SLA surfaces.

Design:

The SBF model was used to compare the bone-like apatite forming ability.

Setting:

The experiment was conducted at Southern Medical University.

Materials and methods:

The quantity of apatite was assessed by SEM and weighed on an electronic balance. The elemental composition and crystal phase were assessed by EDS and XRD analysis, respectively.

Results:

The sediments that completely covered the modSLA and UV-SLA surfaces after 4 weeks of soaking reached 3.23 ± 0.35 mg and 2.13 ± 0.95 mg, respectively. They were eight- and five-fold than that on the SLA surface (0.43 ± 0.15 mg) with statistical significance ( p < 0.05 and p < 0.01, respectively). EDS and XRD tests recognized the sediments on the modSLA and UV-SLA surfaces as apatite with similar elemental compositions, Ca/P ratios and crystal phases.

Discussion:

Hydrophilicity and abundant hydroxyl groups drive modSLA and UV-SLA surfaces to absorb more Ca2+ to accelerate the formation of apatite.

Conclusion:

SLA preservation in dH2O and UV irradiation were recognized as trustworthy methods to acquire greater bioactivity of the SLA surface.

Pediatric morphometric study to guide the optimized implantation of the Osia® 2 implant system

PURPOSE

Continuous technological advances result in the availability of new bone conduction hearing implants, of which their suitability for pediatric patients is of major concern. The Cochlear^TMOsia^® 2 is a new active osseointegrated steady-state implant system that uses digital piezoelectric stimulation to treat hearing loss. The implant in the United States was approved for patients aged 12 years and above, whereas the CE mark is independent of age, the only requirement is body weight of at least 7 kg. Therefore, further clinical studies are required to assess device characteristics in younger patients. The aim of our study was to perform a morphometric study among 5-12-year-old children, and to develop a surgical protocol for Osia 2 system implantation based on these findings.

METHODS

We examined retrospectively cranial CT scans of 5-12-year-old patients from our clinical database. We measured the bone and soft-tissue thickness in the region of interest, and the position of the sigmoid sinus. 3D printed temporal bones were also used for planning.

RESULTS

Soft-tissue thickness varied between 3.2 ± 0.5 mm and 3.6 ± 0.6 mm and bone thickness varied between 3.5 ± 1.1 mm and 4.7 ± 0.3 mm. The sigmoid sinus was located 1.3 ± 0.2 cm posterior to the ear canal, and the anterior distance was 4.8 ± 0.9 to 7.1 ± 1.1 mm.

CONCLUSIONS

Our morphometric studies showed that patients aged 5-12 have different anatomical dimensions compared to adults, but that implantation of the Osia 2 system is feasible in these patients using an altered implant positioning recommended by our data. The Cochlear™ Osia^® 2 is, therefore, an option for hearing rehabilitation in younger pediatrics.

Nanoscale Modification of Titanium Implants Improves Behaviors of Bone Mesenchymal Stem Cells and Osteogenesis In Vivo

The surficial micro/nanotopography and physiochemical properties of titanium implants are essential for osteogenesis. However, these surface characters' influence on stem cell behaviors and osteogenesis is still not fully understood. In this study, titanium implants with different surface roughness, nanostructure, and wettability were fabricated by further nanoscale modification of sandblasted and acid-etched titanium (SLA: sandblasted and acid-etched) by H₂O₂ treatment (hSLAs: H₂O₂ treated SLA). The rat bone mesenchymal stem cells (rBMSCs: rat bone mesenchymal stem cells) are cultured on SLA and hSLA surfaces, and the cell behaviors of attachment, spreading, proliferation, and osteogenic differentiation are further analyzed. Measurements of surface characteristics show hSLA surface is equipped with nanoscale pores on microcavities and appeared to be hydrophilic. In vitro cell studies demonstrated that the hSLA titanium significantly enhances cell response to attachment, spreading, and proliferation. The hSLAs with proper degree of H₂O₂ etching (h1SLA: treating SLA with H₂O₂ for 1 hour) harvest the best improvement of differentiation of rBMSCs. Finally, the osteogenesis in beagle dogs was tested, and the h1SLA implants perform much better bone formation than SLA implants. These results indicate that the nanoscale modification of SLA titanium surface endowing nanostructures, roughness, and wettability could significantly improve the behaviors of bone mesenchymal stem cells and osteogenesis on the scaffold surface. These nanoscale modified SLA titanium scaffolds, fabricated in our study with enhanced cell affinity and osteogenesis, had great potential for implant dentistry.

Surface Modification of Biomedical Ti and Ti Alloys: A Review on Current Advances

Ti is widely used as a material for orthopedic implants. As rapid and effective osseointegration is a key factor for the successful application of implants, biologically inert Ti materials start to show inherent limitations, such as poor surface cell adhesion, bioactivity, and bone-growth-inducing capabilities. Surface modification can be an efficient and effective approach to addressing the biocompatibility, mechanical, and functionality issues of the various Ti implant materials. In this study, we have overviewed more than 140 papers to summarize the recent progress in the surface modification of Ti implants by physical and/or chemical modification approaches, aiming at optimizing their wear resistance, biocompatibility, and antimicrobial properties. As an advanced manufacturing technology for Ti and Ti alloys, additive manufacturing was particularly addressed in this review. We also provide an outlook for future research directions in this field as a contribution to the development of advanced Ti implants for biomedical applications.

Influence of Bone-Level Dental Implants Placement and of Cortical Thickness on Osseointegration: In Silico and In Vivo Analyses

The purpose of this research is to study the biomechanical response of dental implants in bone-level type locations, 0.5 mm above and below the bone level. In addition, the influence of the thickness of the cortical bone on osseointegration is determined due to the mechanical loads transfer from the dental implant to the cortical and trabecular bone. The thicknesses studied were 1.5 mm and 2.5 mm. Numerical simulations were performed using a finite element method (FEM)-based model. In order to verify the FEM model, the in silico results were compared with the results obtained from a histological analysis performed in an in vivo study with 30 New Zealand rabbits. FEM was performed using a computerized 3D model of bone-level dental implants inserted in the lower jawbone with an applied axial load of 100 N. The analysis was performed using different distances from the bone level and different thicknesses of cortical bone. The interface area of bone growth was evaluated by analyzing the bone–implant contact (BIC), region of interest (ROI) and total bone area (BAT) parameters obtained through an in vivo histological process and analyzed by scanning electron microscopy (SEM). Bone-level implants were inserted in the rabbit tibiae, with two implants placed per tibia. These parameters were evaluated after three or six weeks of implantation. FEM studies showed that placements 0.5 mm below the bone level presented lower values of stress distribution compared to the other studied placements. The lower levels of mechanical stress were then correlated with the in vivo studies, showing that this position presented the highest BIC value after three or six weeks of implantation. In this placement, vertical bone growth could be observed up the bone level. The smallest thickness of the study showed a better transfer of mechanical loads, which leads to a better osseointegration. In silico and in vivo results both concluded that the implants placed 0.5 mm below the cortical bone and with lower thicknesses presented the best biomechanical and histological behavior in terms of new bone formation, enhanced mechanical stability and optimum osseointegration.

Thickness of the Buccal and Alveolar Bones Overlying Central Incisors: A Radiographic Iraqi Study

Background. Initial bone thickness has a substantial impact on the success of dental implant treatments. The objective of the current study was to analyze the thickness of the buccal and alveolar bone at the central incisors using CBCT in relation to gender and side to determine the anatomical features and choose the best implant treatment option for minimizing the surgical complications. Methods. One hundred CBCT images were investigated (50 females and 50 males, aged 20 to 50 years old). The buccal bone thickness and alveolar bone thickness were evaluated for right and left sides of each subject at three sites; C: crest (3 mm); M: middle (6 mm); A: apical (9 mm) from the cementoenamel junction. Results. The mean thickness of buccal bone was less than 2 mm on the incisors according to side and gender. Buccal bone thickness revealed a statistically significant difference between right and left sides at the apical point in both females and males with $p$ values of ( $p\le 0.001$ ) and (0.001), respectively. The buccal bone thickness displayed statistically significant differences between genders at all sites. The alveolar thickness demonstrated similar significant differences between genders except for the crest site. Conclusions. Iraqi participants had about 1 mm buccal bone thickness at 3 mm apical from the CEJ in right and left central incisors with a progressive rise in bone thickness to be less than 2 mm at the apex. Alveolar bone also showed the same increase in bone thickness from crest to apex. Bone thickness was greater in males than females. The present study provided valuable CBCT data on bone thickness of the esthetic maxillary region as a preoperative analysis for establishing an immediate implant treatment plan with aesthetically pleasing long-term outcomes.

Oral health-related quality of life of patients rehabilitated with fixed and removable implant-supported dental prostheses

Dental implants have become a mainstream treatment approach in daily practice, and because of their high survival rates over time, they have become the preferred treatment option for prosthetic rehabilitation in many situations. Despite the relatively high predictability of implant therapy and high costs to patients, patient perceptions of success and patient-reported outcome measures have become increasingly significant in implant dentistry. Increasing numbers of publications deal with oral health-related quality of life and/or patient-reported outcome measures. The aim of this paper was to provide an overview of the available evidence on oral health-related quality of life of fully and partially dentate patients rehabilitated with fixed and removable implant-supported dental prostheses. A comprehensive electronic search was performed on publications in English up to 2021. A selection of standardized questionnaires and scales used for the evaluation of oral health-related quality of life were analyzed and explained. The analysis encompassed three aspects: a functional evaluation of oral health-related quality of life, an esthetic assessment of oral health-related quality of life, and a cost-related evaluation of oral health-related quality of life for rehabilitation with dental implants. The data demonstrated that the preoperative expectations of patients markedly affected the outcomes perceived by the patients. As expected, reconstructions supported by implants substantially improved the stability of conventional dentures and allowed improved function and patient satisfaction. However, from a patient's perspective, oral health-related quality of life was not significantly greater for dental implants compared with conventional tooth-supported prostheses. The connection of the implants to the prostheses with locators or balls indicated high oral health-related quality of life. The data also suggest that patient expectation is not a good predictor of treatment outcome. In terms of esthetic outcomes, the data clearly indicate that patients' perceptions and clinicians' assessments differed, with those of clinicians yielding higher standards. There were no significant differences found between the esthetic oral health-related quality of life ratings for soft tissue-level implants compared with those for bone-level implants. Comparison of all-ceramic and metal-ceramic restorations showed no significant differences in patients' perceptions in terms of esthetic outcomes. Depending on the choice of outcome measure and financial marginal value, supporting a conventional removable partial denture with implants is cost-effective when the patient is willing to invest more to achieve a higher oral health-related quality of life. In conclusion, the oral health-related quality of life of patients rehabilitated with implant-supported dental prostheses did not show overall superiority over conventional prosthetics. Clinicians' and patients' evaluations, especially of esthetic outcomes, are, in the majority of cases, incongruent. Nevertheless, patient-reported outcomes are important in the evaluation of function, esthetics, and the cost-effectiveness of treatment with implant-supported dental prostheses, and should be taken into consideration in daily practice.

The Surface Conditions and Composition of Titanium Alloys in Implantology: A Comparative Study of Dental Implants of Different Brands

The success of titanium dental implants depends on their osseointegration into the bone, which is determined by the composition and surface properties of the implant in close contact with the bone. There is a wide variety of implants on the market. Is it possible to identify the implant with the best composition and surface topography for optimal osseointegration? To this aim, 13 brands of dental implants from nine distinct manufacturers have been selected and their composition and surface topography determined. The obtained results show differences between these implants, in this case, the Ssk averages of the three measurements performed on each implant were positive, or 0.4 (0.1-0.8), indicating that the roughness of all implants analyzed was primarily textured and not flat. Like Sa, we found the highest Sdr for implants subjected only to sandblasting. In addition, only the ALS-active^® implant had a modified microstructure on its surface. However, analysis of the NANOTITE implant surface revealed a 1.40% presence of calcium which we consider too low to have an effect on bone formation around the implant. As a result, we have also highlighted the lack of a recognized independent standard for dental implant surface conditions and the lack of independent quality control vis-à-vis manufacturers. Of all the surface types studied, none proved more satisfactory than another.

Reconstruction of Ipsilateral Femoral and Tibial Bone Defect by 3D Printed Porous Scaffold Without Bone Graft: A Case Report

CASE

This study reported the case of a 42-year-old woman with traumatic ipsilateral critical bone defect of right femur and tibia after a motor accident. Three-dimensional (3D) printed porous titanium scaffolds were innovatively used to reconstruct this challenging situation. The initial stability was safe enough for early exercise and partial weight bearing. The 26-month follow-up showed osseous integration of the prosthesis-bone interface with short-term satisfactory clinical result.

CONCLUSION

The custom-designed 3D-printed porous scaffold has the potential to become an effective option for reconstructing the segmental irregular-shaped bone defect.

Alveolar Bone Marrow Gli1+ Stem Cells Support Implant Osseointegration

Osseointegration is the key issue for implant success. The in vivo properties of cell populations driving the osseointegration process have remained largely unknown. In the current study, using tissue clearing-based 3-dimensional imaging and transgenic mouse model-based lineage tracing methods, we identified Gli1+ cells within alveolar bone marrow and their progeny as the cell population participating in extraction socket healing and implant osseointegration. These Gli1⁺ cells are surrounding blood vessels and do not express lineage differentiation markers. After tooth extraction and delayed placement of a dental implant, Gli1⁺ cells were activated into proliferation, and their descendants contributed significantly to new bone formation. Ablation of Gli1⁺ cells severely compromised the healing and osseointegration processes. Blockage of canonical Wnt signaling resulted in impaired recruitment of Gli1⁺ cells and compromised bone healing surrounding implants. Collectively, these findings demonstrate that Gli1⁺ cells surrounding alveolar bone marrow vasculature are stem cells supporting dental implant osseointegration. Canonical Wnt signal plays critical roles in regulating Gli1⁺ stem cells.

Esthetic And Functional Integration Of Soft Tissue Around Dental Implants: Thickness, Width, Stability

The long-term Functional success of the implant treatment depends on the stability of the crestal bone tissue around the implant platform. The Esthetic result is achieved by an adequate soft tissue in the peri-implant zone. Furthermore, the soft tissue creates the buffer area that ensures the mechanical and biological protection of the underlying bone. Therefore, it is necessary to maintain for a long term, not only the implant osseointegration but also the integration of the soft tissue around the Sub and Supra-structure of the restoration. In order to create the protective soft tissue area, it is necessary to ensure three criteria. This treatment approach will be defined as the TWS - Soft Tissue Management : T for Thickness , W for Width, and S for Stability . The purpose of this article is to present with clinical cases, the detailed description of each criteria. There are many ways to achieve the two first criteria and they are well described in the literature. Achieving the third criteria of the Stability become possible only in the last years since the development of the digital technology and its implementation into the dental practice. A one time abutment and the creation of peri- implant mucosal thickness with an optimal amount of the attached keratinized gingiva above and around the implant platform, for muco-gingival integration of the system, are therefore a prerequisite for functional and esthetic result. The article presents the possibility for the clinicians to use in their daily practice this new clinical approach of TWS - Soft Tissue Management.

Culture and characterization of various porcine integumentary-connective tissue-derived mesenchymal stromal cells to facilitate tissue adhesion to percutaneous metal implants

Background

Transdermal osseointegrated prosthesis have relatively high infection rates leading to implant revision or failure. A principle cause for this complication is the absence of a durable impervious biomechanical seal at the interface of the hard structure (implant) and adjacent soft tissues. This study explores the possibility of recapitulating an analogous cellular musculoskeletal-connective tissue interface, which is present at naturally occurring integumentary tissues where a hard structure exits the skin, such as the nail bed, hoof, and tooth.

Methods

Porcine mesenchymal stromal cells (pMSCs) were derived from nine different porcine integumentary and connective tissues: hoof-associated superficial flexor tendon, molar-associated periodontal ligament, Achilles tendon, adipose tissue and skin dermis from the hind limb and abdominal regions, bone marrow and muscle. For all nine pMSCs, the phenotype, multi-lineage differentiation potential and their adhesiveness to clinical grade titanium was characterized. Transcriptomic analysis of 11 common genes encoding cytoskeletal proteins VIM (Vimentin), cell–cell and cell–matrix adhesion genes (Vinculin, Integrin β1, Integrin β2, CD9, CD151), and for ECM genes (Collagen-1a1, Collagen-4a1, Fibronectin, Laminin-α5, Contactin-3) in early passaged cells was performed using qRT-PCR.

Results

All tissue-derived pMSCs were characterized as mesenchymal origin by adherence to plastic, expression of cell surface markers including CD29, CD44, CD90, and CD105, and lack of hematopoietic (CD11b) and endothelial (CD31) markers. All pMSCs differentiated into osteoblasts, adipocytes and chondrocytes, albeit at varying degrees, under specific culture conditions. Among the eleven adhesion genes evaluated, the cytoskeletal intermediate filament vimentin was found highly expressed in pMSC isolated from all tissues, followed by genes for the extracellular matrix proteins Fibronectin and Collagen-1a1. Expression of Vimentin was the highest in Achilles tendon, while Fibronectin and Col1agen-1a1 were highest in molar and hoof-associated superficial flexor tendon bone marrow, respectively. Achilles tendon ranked the highest in both multilineage differentiation and adhesion assessments to titanium metal.

Conclusions

These findings support further preclinical research of these tissue specific-derived MSCs in vivo in a transdermal osseointegration implant model.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02666-2.

Implant Stability Changes for a Single Implant Mandibular Overdenture

Objectives  To compare the changes in implant stability for the nonsubmerged and submerged protocols for a single-implant retained mandibular overdenture using Cendres and Metaux Locator attachment throughout a 24-month follow-up.

Materials and Methods  Eighty edentulous patients who were seeking to install a single implant in the midline of the completely edentulous mandible. At the day of implant installation, patients were randomized into two groups using sealed envelopes: the nonsubmerged and submerged groups. After 3 months of healing period, randomization using sealed envelopes was performed and patients were randomized to receive the Cendres and Metaux Locator attachment. The periotest readings were recorded using the Periotest M device, every 3 months for the first year and annually in the second year. The scope of this clinical trial focused only on results of the Cendres and Metaux attachment.

Statistical Analysis  The Mann–Whitney U -test was used for comparison between study groups for independent samples. Two-sided p -values less than 0.05 were considered statistically significant.

Results  There was no statistically significant difference between the mean periotest readings of both groups throughout the 24-month follow-up. Both groups showed an improvement in mean periotest readings with the submerged group tending to show greater stability at 6, 12, and 24-month follow-ups.

Conclusions  The nonsubmerged and the submerged healing protocols resulted in reliable periotest readings with the submerged group showing greater improvement than the nonsubmerged, although this improvement is nonsignificant when using the Cendres and Metaux attachment for a single mandibular overdenture.

Mechanobiological model to study the influence of screw design and surface treatment on osseointegration

This study aims at suggesting a new approach to peri-implant healing models, providing a set of taxis-diffusion-reaction equations under the combined influence of mechanical and biochemical factors. Early events of osseointegration were simulated for titanium screw implants inserted into a pre-drilled trabecular bone environment, up to 12 weeks of peri-implant bone healing. Simulations showed the ability of the model to reproduce biological events occurring at the implant interface through osteogenesis. Implants with shallow healing chamber showed higher proportions of lamellar bone, enhanced by the increase of mechanical stimulation. Osteoconduction was observed through the surface treatment model and similar bone healing patterns compared to in vivo studies.

Medication-Related Osteonecrosis of the Jaw Subsequent to Peri-Implantitis: A Case Report and Literature Review

The aim of this report was to document a rare case of medication-related osteonecrosis of the jaw (MRONJ) that developed around the already osseointegrated implants in the maxillary right molar region. A 73-year-old woman presented at our university dental hospital in May 2017 with a chief complaint of discomfort near a maxillary implant. Her first visit was in 2006, and the maintenance treatment began in 2007 after the periodontal treatment. During the implant maintenance period there were no complications; however, the patient began taking alendronate sodium hydrate (Fosamac tablets, 35 mg, once weekly), an oral bisphosphonate (BP) since 2013, for treatment of osteoporosis. Eight years after starting implant maintenance, in 2016, peri-implantitis occurred, for which mechanical cleaning and antimicrobial therapy were performed. Peri-implantitis symptoms disappeared, and the medical condition improved. Nonetheless, in 2017, MRONJ developed 4 years after she commenced taking the BP. The patient underwent implant removal and sequestrectomy. There was no postoperative recurrence. Since it was such a rare case, we performed a literature review but only discovered a few similar cases. Because various triggers may lead to the development of MRONJ, even if already osseointegrated implant, it is important to note that implants in patients taking BPs should be more carefully maintained.

Comparative evaluation of crestal bone level by flapless and flap techniques for implant placement: Systematic review and meta-analysis

Aim

:To compare the crestal bone level of flapless technique of dental implant placement with the flap technique.

Setting and Design

This Systematic review and Meta-analysis was conducted according to the Preferred Reporting Items For Systematic Review and Meta-Analyses (PRISMA) Guidelines and registered with PROSPERO.

Materials and Methods

Electronic search of Medline and Google scholar databases for articles from 2010 till March 2020 was performed. Studies comparing the crestal bone level with both the techniques were included. After the collection of data, the risk of bias was assessed for each study.

Statistical Analysis Used

Meta-analysis was executed using RevMan 5 software version 5.3.

Results

23 studies were included. Statistically significant difference in crestal bone level was found between flapless and flap surgery with mean difference of -0.14 (flapless placement versus flap surgery; 95% CI: -0.24 to -0.03; P = 0.01FNx01). The difference in crestal bone level between the 2 groups was not statistically significant with a mean difference of -0.05(Guided flapless placement versus flap surgery; 95% CI: -0.10 to 0.00; P=0.06). Meta-analysis of the freehand flapless surgery with flap surgery generated a mean difference of -0.20 which was found to be statistically significant (Freehand flapless placement versus flap surgery; 95% CI: -0.37 to -0.03; P=0.02FNx01).

Conclusions

Flapless placement of implant can positively influence crestal bone loss in comparison with conventional flap technique.

Occurrence and severity of spontaneous exposure of cover screw after dental implant placement

Background. Perforation of the soft tissues overlying the dental implant, resulting in early and spontaneous exposure of cover screws between stages I and II of the two-staged implant placement procedure, is a common problem that can disrupt the primary repair and osseointegration process. The present study aimed to investigate the prevalence of spontaneous exposure of cover screws in dental implants and identify the related risk factors.Methods. The present retrospective, descriptive-analytical study enrolled 40 patients with 182 dental implants in the second stage of the implant placement procedure. Data on patient-related and implant-related classified variables were collected, and all the samples were examined for cover screw exposure based on the classification by Tal. First, the overall prevalence of cover screw exposure was calculated. Then, statistical analysis was performed using SPSS 24 to investigate the effect of different variables on this exposure. The chi-squared test was used at the bivariate level, while the logistic regression was used at the multivariate level.Results. Of 40 participants with 182 implants, 17 implants (9.3%) in 9 patients (22.5%) became exposed to the oral cavity. In terms of severity, Class I exposure was the most common with seven implants. Moreover, Class III was the least common with only one implant. Using the logistic regression analysis, we found significant relationships between the dental implant exposure and the variables of overlying mucosal thickness (OR=24.7, P≤0.001), the duration between tooth extraction and implant placement (OR=9.6, P=0.005), and implant location in the jaw (OR=3.8, P=0.033). Moreover, exposure was more common in the maxillary premolar area (22.5%) than in other locations. Also, there was a significant relationship between implant exposure and lateral augmentation (OR=0.20, P=0.044), indicating the higher risk of exposure in implants with lateral augmentation than those without augmentation.Conclusion. Despite the limitations of this retrospective study, its results showed that three factors, including the overlying mucosal thickness of <2 mm, implant placement in fresh extraction sockets, and maxillary implants, especially at the location of maxillary premolars, were strong predictors of spontaneous implant exposure.

Changes in the Area Adjacent to the Internal Receiver-Stimulator of Cochlear Implant: A Retrospective Study

BACKGROUND

In some patients with cochlear implants, bony resorption at the internal receiver-stimulator site can be observed on postoperative computed tomography. Therefore, it is essential to elucidate the effects of the internal receiver-stimulator on the scalp and bony bed over time.

OBJECTIVE

We aimed to evaluate how the internal receiver-stimulator of a cochlear implant device changed the thickness of the surrounding scalp and skull over time using computed tomography.

METHODS

This retrospective study evaluated patients who underwent cochlear implantation and received two computed tomography scans postoperatively for different indications at a tertiary referral centre. The main outcomes were scalp thickness and bony bed depth.

RESULTS

Fourteen ears were included in this study. There was very good inter-rater reliability, with a Cronbach's alpha of 0.94. The mean scalp thickness over the internal receiver-stimulator was 6.02 (+/-2.4) mm in the first scan and decreased with no significant change to 5.62 mm (+/-1.64) in the second scan (p = 0.59, paired t-test). The mean depth of the bony bed increased significantly from 1.39 mm (+/-0.93) to 2.62 mm (+/-1.24) (p = 0.03).

CONCLUSION

There was no change in the thickness of the scalp overlying the internal receiver-stimulator indicating that the scalp was more resistant than the bony skull to the tensile pressure exerted by the internal receiver-stimulator. In contrast, the bony bed depth of the internal receiver-stimulator increased over time. This can result in decreased internal receiver-stimulator protrusion and decreased risk of device displacement and migration.

Critical Role of Etching Parameters in the Evolution of Nano Micro SLA Surface on the Ti6Al4V Alloy Dental Implants

The surface of dental implants plays a vital role in early and more predictable osseointegration. SLA (sandblasted large grit and acid-etched) represents the most widely accepted, long-term clinically proven surface. Primarily, dental implants are manufactured by either commercially pure titanium (CP-Ti) or Ti6Al4V ELI alloy. The acid etch behavior of CP-Ti is well known and its effects on the surface microstructure and physicochemical properties have been studied by various researchers in the past. However, there is a lack of studies showing the effect of acid etching parameters on the Ti6Al4V alloy surface. The requirement of the narrow diameter implants necessitates implant manufacturing from alloys due to their high mechanical properties. Hence, it is necessary to have an insight on the behavior of acid etching of the alloy surface as it might be different due to changed compositions and microstructure, which can further influence the osseointegration process. The present research was carried out to study the effect of acid etching parameters on Ti6Al4V ELI alloy surface properties and the optimization of process parameters to produce micro- and nanotopography on the dental implant surface. This study shows that the Ti6Al4V ELI alloy depicts an entirely different surface topography compared to CP-Ti. Moreover, the surface topography of the Ti6Al4V ELI alloy was also different when etching was done at room temperature compared to high temperature, which in turn affected the behavior of the cell on these surfaces. Both microns and nano-level topography were achieved through the optimized parameters of acid etching on Ti6Al4V ELI alloy dental implant surface along with improved roughness, hydrophilicity, and enhanced cytocompatibility.

Patient-Centered Treatment Outcomes with Full-Arch PEEK Rehabilitation Supported on Four Immediate or Conventionally Loaded Implants. A Randomized Clinical Trial

This study aims to assess the treatment outcomes (functional and subjective) of full-arch fixed hybrid rehabilitations made of PEEK (poly-ether-ether-ketone) with milled crowns of nano-filled composite (NFC) supported on four to six implants. In this randomized clinical trial, 34 edentate patients in the upper and/or the lower jaws were treated with the fixed hybrid dentures. In 16 patients (47.1% of the sample), the implants were loaded immediately (IL) by means of a provisional fixed rehabilitation made of PMMA (polymethylmethacrylate) screwed on Multi-Unit (MU) abutments connected after emplacement of the implant; however, in the counterparts (n = 18) these MU abutments were covered by healing caps and were left unloaded during two months (conventional loading protocol—CL), when all patients received a fixed hybrid PEEK-NFC rehabilitation on the upper and/or the lower jaw. Treatment outcomes were assessed 12 months after prostheses delivery. Functional outcomes were calculated according to masticatory performance, estimated by mixing ability tests of two colored chewing gums after ten chewing strokes, by the occlusal force/area recorded by pressure-sensitive sheets, and by electromyography of masseters and temporal muscles at maximum biteforce. The subjective outcomes of the treatment were assessed using both the oral satisfaction scale (visual analog scale) and the Spanish version of the Oral Health Impact Profile (OHIP-20). The findings of the present study showed that treatment with fixed PEEK-NFC hybrid prostheses significantly improved the masticatory performance, bite force, occlusal pattern, quality of life, and satisfaction, with the IL group being those with significantly higher occlusal bite forces and greater satisfaction in comparison with CL group. It should be concluded that PEEK-NFC hybrid prostheses can improve several patient-centered outcomes and that loading protocol significantly affects the patient’s self-rated satisfaction.

Implant Stability Changes for Nonsubmerged and Submerged Protocols for a Single Implant Mandibular Overdenture Using Ball Attachment

Objectives

To compare the changes in implant stability for the nonsubmerged (NS) and submerged (S) protocols for the single implant retained mandibular overdenture using ball attachment throughout a 24-month follow-up.

Materials and Methods

Eighty completely edentulous patients were seeking to improve retention of their lower complete denture by installing a single implant in the midline of the completely edentulous mandible. At the day of implant installation, patients were randomized into 2 groups using sealed envelopes: the nonsubmerged (NS) and submerged (S) group. After a 3-month healing period, all patients were randomized using sealed envelopes into ball attachment and CM-LOC attachment. The Periotest readings (PTV) was recorded using the Periotest M device and was recorded every 3 months for the first year and then annually in the second year. The scope of this clinical trial focused only on results of the ball attachment. The Mann–Whitney U test was used for comparison between study groups for independent samples. Two-sided p values less than 0.05 was considered statistically significant.

Results

There was no statistically significant difference in the mean change in PTV reading between the NS and S group at the different follow-up intervals. Initially, at the day of pickup (baseline) and 3-month follow-up, the mean PTV reading for the NS was greater than that of the S group (−4.471 ± 1.489, −4.391 ± 1.4727 (p=0.913)), while the S group has shown a greater improvement in PTV than the NS group after 6-month follow-up and continued throughout the 24-month follow-up (−5.730 ± 1.7804, −50855 ± 1.2581 (p=1)).

Conclusion

Both the nonsubmerged and the submerged healing protocol have shown reliable Periotest readings using ball attachment for a single implant retained overdenture. The submerged group has resulted in a greater improvement in Periotest readings after the 12- and 24-month follow-up period when compared to the nonsubmerged group although this improvement was not statistically significant.

Immediate Implant Placement and Provisionalization in the Esthetic Zone: A 6.5-Year Follow-Up and Literature Review

The success of dental implant therapy in the esthetic zone requires not only functional osseointegration but also a satisfactory esthetic outcome. To establish harmony, balance, and continuity of gingival architecture between an implant restoration and the adjacent natural dentition is challenging. Immediate implant placement and provisionalization following tooth extraction have been documented as a predictable treatment modality, with fewer surgical interventions needed, to replace a missing tooth in the esthetic zone. This case report illustrates immediate implant placement and provisionalization to replace a failing maxillary right central incisor while maintaining optimal gingival esthetics. The maxillary right central incisor was extracted without flap elevation to minimize soft and hard tissue trauma. Immediately afterwards, the implant was installed using a surgical stent and restored with a provisional crown that had no occlusal contacts. During healing, no significant adverse effects were observed clinically or radiographically. This proposed treatment modality provided the patient with immediate esthetics, function, and comfort without any complications during a follow-up period of 6.5 years.

Dental Implant Nano-Engineering: Advances, Limitations and Future Directions

Titanium (Ti) and its alloys offer favorable biocompatibility, mechanical properties and corrosion resistance, which makes them an ideal material choice for dental implants. However, the long-term success of Ti-based dental implants may be challenged due to implant-related infections and inadequate osseointegration. With the development of nanotechnology, nanoscale modifications and the application of nanomaterials have become key areas of focus for research on dental implants. Surface modifications and the use of various coatings, as well as the development of the controlled release of antibiotics or proteins, have improved the osseointegration and soft-tissue integration of dental implants, as well as their antibacterial and immunomodulatory functions. This review introduces recent nano-engineering technologies and materials used in topographical modifications and surface coatings of Ti-based dental implants. These advances are discussed and detailed, including an evaluation of the evidence of their biocompatibility, toxicity, antimicrobial activities and in-vivo performances. The comparison between these attempts at nano-engineering reveals that there are still research gaps that must be addressed towards their clinical translation. For instance, customized three-dimensional printing technology and stimuli-responsive, multi-functional and time-programmable implant surfaces holds great promise to advance this field. Furthermore, long-term in vivo studies under physiological conditions are required to ensure the clinical application of nanomaterial-modified dental implants.

Secondary stability achieved in dental implants with a calcium-coated sandblasted, large-grit, acid-etched (SLA) surface and a chemically modified SLA surface placed without mechanical engagement: A preclinical study

OBJECTIVES

To assess the osseointegration of calcium-coated (CS) and chemically modified, sandblasted, large-grit, acid-etched (MS) dental implants with a lack of primary mechanical stability.

MATERIALS AND METHODS

Eighteen implants in CS and MS groups each were loosely placed in the mandible of six mongrel dogs and allowed to heal for 2, 4 and 8 weeks. Implant stability quotient (ISQ) and implant stability test (IST) values recorded periodically and bone-to-implant contact (BIC) and the number of Haversian canals per 1 mm² measured histologically were statistically analysed (p < .05).

RESULTS

All CS and MS implants placed survived. Compared with immediately after installation, ISQ and IST values in both groups increased significantly to over 76 at 2 weeks (p < .0083) and remained stable thereafter. BIC was significantly greater at 8 weeks (61.3 ± 13.6% in CS group; 57.6 ± 5.9% in MS group) compared to 2 and 4 weeks in both groups (p < .017). There were no significant intergroup differences in ISQ, IST or BIC at different time points. Significantly more Haversian canals were observed in group CS (6.2 ± 1.0/mm² ) compared with group MS at 4 weeks (3.7 ± 1.8 /mm² ; p < .05), while intergroup difference was not significant at 8 weeks.

CONCLUSION

Both CS and MS implants inserted without primary stability obtained osseointegration within 2 weeks, and lamellar bone adjacent to the implants was first observed at 8 weeks. The formation of primary osteons was more active at 4 weeks in group CS than in group MS.

Effect of Ag alloying and trace precipitation on corrosion resistance of Ti-Ta-Ag ternary alloy

This work systematically analysed the electrochemical and corrosion behaviour of Ti-Ta-Ag ternary alloy samples in Hank's solution. For the samples with 1.5% and 3% Ag content, the sintering temperature increased from 750 to 950°C, and the corresponding corrosion resistance increased by 100 times due to the increased alloying of Ag; meanwhile for the sample with 4.5% Ag content, the sintering temperature increased from 750 to 950°C, and the corresponding corrosion resistance decreased by six times due to the increased precipitation of Ag. These tests prove that the Ag alloying is beneficial to the enhancement of the corrosion resistance of Ti-Ta-Ag ternary alloy, but the Ag trace precipitation has the opposite effect. A series of electrochemical characterizations and density functional theory calculations explain the mechanism of the above phenomenon. Ag alloying can promote the formation of uniform, complete, dense, stable and thick passivation layer on the surface of Ti-Ta-Ag ternary alloy, which makes Ti-Ta-Ag ternary alloy uniformly corroded without pitting. In addition, Ag alloying can effectively reduce the contact resistance of the solid-liquid interface. However, the trace precipitation of Ag plays the opposite role to the above effect.

The molecular pathway triggered by zirconia in endothelial cells involves epigenetic control

The requirement to achieve natural looking restorations is one of the most challenging aspects in dentistry. Although zirconia has provided new opportunities for achieving superior aesthetics and physicochemical outcomes, very little has been achieved for its cellular and molecular performance, especially considering angiogenesis and osteogenesis. As angiogenesis is a secondary event and concomitant to osteogenesis, an indirect effect of dental implant on endothelial cells could be the release of active molecules such as those already reported affecting osteoblasts. To better address this issue, we challenged human endothelial cells (HUVECs) with zirconia-conditioned medium up to 72 h to allow analysis specific gene expression and protein pattern of mediators of epigenetic machinery in full. Our data shows involvement of zirconia in triggering intracellular signaling through MAPK-ERK activation, leading the signal to activate histone deacetylase HDAC6 likely with concomitant well-modulated DNA methylation profile by DNMTs and TETs. These signaling pathways seem to culminate in cytoskeleton rearrangement of endothelial cells, an important prerequisite to cell migration expected in angiogenesis. Collectively, this study demonstrates for the first time epigenetic-related molecular mechanism involved in endothelial cells responding to zirconia, revealing a repertoire of signaling molecules capable of executing the reprogramming process of gene expression, which are necessary to drive cell proliferation, migration, and consequently angiogenesis. This set of data can further studies using gene editing approaches to better elucidate functional roles.

Peri-Implantitis Regenerative Therapy: A Review

Simple Summary

Regenerative therapies are one of the options to treat peri-implantitis diseases that cause peri-implant bone loss. This review reports classic and current literature to describe the available knowledge on regenerative peri-implant techniques.

Abstract

The surgical techniques available to clinicians to treat peri-implant diseases can be divided into resective and regenerative. Peri-implant diseases are inflammatory conditions affecting the soft and hard tissues around dental implants. Despite the large number of investigations aimed at identifying the best approach to treat these conditions, there is still no universally recognized protocol to solve these complications successfully and predictably. This review will focus on the regenerative treatment of peri-implant osseous defects in order to provide some evidence that can aid clinicians in the approach to peri-implant disease treatment.

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.

Functional and Patient-Centered Treatment Outcomes with Mandibular Overdentures Retained by Two Immediate or Conventionally Loaded Implants: A Randomized Clinical Trial

This study aims to assess the treatment outcomes (functional and subjective) of mandibular overdentures retained on two implants with or without an immediate loading protocol. In this randomized clinical trial, twenty fully edentulous patients were treated with a mandibular two-implant-retained overdenture and a complete new maxillary denture. In half of the sample, the implants were loaded immediately by means of VulkanLoc^® abutments after emplacement of the implant, but in the counterparts, these VulkanLoc^® abutments were connected to implants two months after the surgery (conventional protocol), and until that time the dentures were retained by healing abutments. Treatment outcomes were assessed at two, six, and twelve months after surgery. Functional outcomes were calculated according to masticatory performance, estimated by the mixed fraction of a two-coloured chewing gum after five, ten, and fifteen chewing strokes, by the occlusal force recorded by pressure-sensitive sheets, and by the bioelectrical muscular activity. The subjective outcomes of the treatment were assessed using both the oral satisfaction scale (visual analogue scale) and the Spanish version of the Oral Health Impact Profile (OHIP-20). The findings of the present study show that new complete dentures resulted in significant improvements in chewing ability, patient satisfaction, and oral health-related quality of life and that subsequent implant-retained overdentures produced further and faster significant improvements. The loading protocol may influence those positive self-reported outcomes rather than the objective functional evaluations.

Conferred with a new life: A case report of management of a severe midface trauma and subsequent oral rehabilitation

Maxillofacial traumas have been associated with 14%-17% of all facial injuries. The most common etiology of mid-facial traumas is motor vehicle accidents followed by interpersonal assaults. The devastating nature of maxillofacial defects makes reconstruction of the midface challenging, due to multiple required surgeries and extensive rehabilitation phase. The midface has been defined as the area between the zygomaticofrontal sutures and the maxillary occlusal plane. Midface traumas are significantly more challenging to manage compared to isolated facial since there is limited intact and unharmed framework to guide with anatomic reductions. Therefore, the appropriate surgical approach to a maxillofacial trauma must follow a systematic scheme. Besides, one of the main consequences of maxillofacial traumas is destruction of the teeth and teeth bearing alveolar bone. Oral rehabilitation utilizing dental implants of these patients must be considered to provide the higher quality of life. Here, we report the management and further oral rehabilitation of a case suffering severe midface trauma following a motor vehicle accident where the patient was hit by a lorry.

Binding of collagen gene products with titanium oxide

Titanium is the only metal to which osteoblasts can adhere and on which they can grow and form bone tissue in vivo, resulting in a strong bond between the implant and living bone. This discovery provides the basis for the universal medical application of Ti. However, the biochemical mechanism of bond formation is still unknown. We aimed to elucidate the mechanism of bond formation between collagen, which constitutes the main organic component of bone, and TiO₂, of which the entire surface of pure Ti is composed. We analysed the binding between the soluble collagen and TiO₂ by chromatography with a column packed with Ti beads of 45 µm, and we explored the association between collagen fibrils and TiO₂ (anatase) powders of 0.2 µm. We ran the column of chromatography under various elution conditions. We demonstrated that there is a unique binding affinity between Ti and collagen. This binding capacity was not changed even in the presence of the dissociative solvent 2M urea, but it decreased after heat denaturation of collagen, suggesting the contribution of the triple-helical structure. We propose a possible role of periodically occurring polar amino acids and the collagen molecules in the binding with TiO₂.

Methods of Topical Administration of Drugs and Biological Active Substances for Dental Implants-A Narrative Review

Dental implants are, nowadays, established surgical devices for the restoration of lost teeth. Considered as an alternative for traditional prosthetic appliances, dental implants surpass them in reliability and patient feedback. Local drug delivery around the implants promotes osseointegration and reduces peri-implantitis. However, there are currently no methods of a multiple, precise topical administration of drugs to the implant area. Engineering coatings on the implants, drug application on carriers during implantation, or gingival pockets do not meet all requirements of dental surgeons. Therefore, there is a need to create porous implants and other medical devices that will allow a multiple drug delivery at a controlled dose and release profile without traumatic treatment. Due to the growing demand for the use of biologically active agents to support dental implant treatment at its various stages (implant placement, long-term use of dental superstructures, treatment of the peri-implant conditions) and due to the proven effectiveness of the topical application of pharmacological biologically active agents to the implant area, the authors would like to present a review and show the methods and devices that can be used by clinicians for local drug administration to facilitate dental implant treatment. Our review concludes that there is a need for research in the field of inventions such as new medical devices or implants with gradient solid-porous structures. These devices, in the future, will enable to perform repeatable, controllable, atraumatic, and repeatable injections of active factors that may affect the improvement of osteointegration and the longer survival of implants, as well as the treatment of peri-implantitis.

Influence of an Implant Fixture including a Freely Removable Micro-Locking Implant Prosthesis on Peri-Implant Tissues and Implant Prostheses: A Prospective Clinical Study

This prospective study was undertaken to evaluate the clinical usefulness of a newly developed one-piece, screw-free, and micro-locking implant system, which was designed to overcome the shortcomings of the existing implant systems. Thirty-eight patients were recruited and randomly and equally assigned to an experimental group (micro-locking one-piece fixture, MLF; n = 19) or a control group (micro-locking abutment, MLA). Cumulative implant survival rates, marginal bone resorptions, probing depths, plaque indices, bleeding indices, and complications were obtained by using clinical and radiographic findings at 6 months and 12 months after prosthesis placement. Complications that occurred multiple times for single implants were counted. During the 12 month observation period, survival rates were 100% in both groups. No significant intergroup differences were observed for marginal bone resorption, probe depth, or bleeding index. However, mean plaque index was significantly lower in the MLF group at 12 months (p < 0.05). During the 12-month observation period, food impaction (26.3%) was the main complication in the MLF group and screw loosening (5.3%), prosthesis detachment (5.3%), and food impaction (5.3%) were observed in the MLA group. The results of this study suggest that the one-piece micro-locking implant system offers a predictable treatment method.

Effect of Titanium and Zirconium Oxide Microparticles on Pro-Inflammatory Response in Human Macrophages under Induced Sterile Inflammation: An In Vitro Study

The wear-debris particles released by shearing forces during dental implant insertion may contribute to inflammatory reactions or osteolysis associated with peri-implantitis by stimulating inflammasome-activation. The study aim was to examine cytotoxic and pro-inflammatory effects of titanium (TiO₂) and zirconia (ZrO₂) particles in macrophages regarding their nature/particle concentration over time under sterile lipopolysaccharide (LPS) inflammation. Macrophages were exposed to TiO₂ and ZrO₂ particles (≤5 µm) in cell culture. Dental glass was used as inert control and LPS (1 μg/mL) was used to promote sterile inflammation. Cytotoxicity was determined using MTT assays and cytokine expression of TNF-α, IL-1β and IL-6 was evaluated by qRT-PCR. Data were analyzed using Student's t-test and ANOVA (p ≤ 0.05). Cytotoxicity was significantly increased when exposed to higher concentrations of glass, TiO₂ and ZrO₂ (≥10⁷ particles/mL) compared to controls (p ≤ 0.05). Macrophages challenged with TiO₂ particles expressed up to ≈3.5-fold higher upregulation than ZrO₂ from 12 to 48 h. However, when exposed to LPS, TiO₂ and ZrO₂ particle-induced pro-inflammatory gene expression was further enhanced (p ≤ 0.05). Our data suggest that ZrO₂ particles produce less toxicity/inflammatory cytokine production than TiO₂. The present study shows that the biological reactivity of TiO₂ and ZrO₂ depends on the type and concentration of particles in a time-dependent manner.

Reactivity of Titanium Dental Implant Surfaces in Simulated Body Fluid

Osseointegration of titanium (Ti) implants in bone is crucial for dental implant treatment. Bacterial challenge possibly leading to peri-implantitis threatens long-term success. For the improvement of osseointegration, an understanding of materials and tissue intervention is needed. This in vitro study analyzed changes of different implant surfaces exposed to simulated body fluid (SBF). Implants were analyzed by scanning electron microscopy/X-ray photoelectron spectroscopy. Supernatants (SNs) were assessed using inductively coupled plasma-mass spectrometry (ICP-MS). Additional calcium (Ca) and phosphate (P) crystals developed (Hank's buffered salt solution (HBSS)) on implants with layered surfaces. ICP of SN demonstrated a decreased Ca/P ratio. After incubation with human serum (HS), layers appeared flattened containing <1% Ca/P. The etched/machined implants showed the formation of a surface transformation layer or coating consisting of crystalline Ca/P precipitations and a decrease in the Ca/P ratio in the supernatant. Incubation in HS induced noncrystalline coverage, and increased Ti/Ca/P was detected in supernatants. HBSS induced crystals on surfaces of modified implants and crystalline covers on nonmodified implants containing Ca/P. The serum did not show the development of HA-like structures but showed dissolving effects. Titanium surfaces show completely altered behavior when incubated in serum-containing SBF.

Effects of local application of the ankaferd blood stopper on osseointegration in three different surface titanium implants

Objective

Researchs of the effects of ankaferd blood stopper (ABS) on bone healing metabolism have revealed that it affects bone regeneration positively. The exact mechanism by which this positive effect on bone tissue metabolism is not known. The aim of this study is to biomechanic and biochemical analysis of the effects of the local ABS application on osseointegration of 3 different surfaced titanium implants.

Material & Methods

Spraque dawley rats were divided machined surfaced (MS) (n ​= ​10), sandblasted and large acid grid (SLA) (n ​= ​10) and resorbable blast material (RBM) (n ​= ​10) surfaced implants. ABS applied locally during the surgical application of the titanium implant before insertion in bone sockets. After 4 weeks experimental period the rats sacrificed and implants with surrounding bone tissues were removed to reverse torque analysis (Newton), blood samples collected to biochemical analysis (ALP, calcium, P).

Results

Biomechanic bone implant contact ratio detected higher in SLA surfaced implants compared with the RBM and controls (P ​< ​0,05). Phosphor levels detected lower in RBM implant group compared with the controls and SLA (P ​< ​0,05). Additionally; phosphor levels detected highly in controls compared with the RBM implants.

Conclusion

According the biomechanical parameters ABS may be more effective in SLA and RBM surfaced implants when locally applied.

A systematic review on the effect of inorganic surface coatings in large animal models and meta-analysis on tricalcium phosphate and hydroxyapatite on periimplant bone formation

The aim of the present systematic review was to analyse studies using inorganic implant coatings and, in a meta‐analysis, the effect of specifically tricalcium phosphate (TCP) and hydroxyapatite (HA) implant surface coatings on bone formation according to the PRISMA criteria. Inclusion criteria were the comparison to rough surfaced titanium implants in large animal studies at different time points of healing. Forty studies met the inclusion criteria for the systematic review. Fifteen of these analyzed the bone‐to‐implant contact (BIC) around the most investigated inorganic titanium implant coatings, namely TCP and HA, and were included in the meta‐analysis. The results of the TCP group show after 14 days a BIC being 3.48% points lower compared with the reference surface. This difference in BIC decreases to 0.85% points after 21–28 days. After 42–84 days, the difference in BIC of 13.79% points is in favor of the TCP‐coatings. However, the results are not statistically significant, in part due to the fact that the variability between the studies increased over time. The results of the HA group show a significant difference in mean BIC of 6.94% points after 14 days in favor of the reference surface. After 21–28 days and 42–84 days the difference in BIC is slightly in favor of the test group with 1.53% points and 1.57% points, respectively, lacking significance. In large animals, there does not seem to be much effect of TCP‐coated or HA‐coated implants over uncoated rough titanium implants in the short term.

De novo bone formation around implants with a surface based on a monolayer of multi-phosphonate molecules. An experimental in vivo investigation

OBJECTIVES

The purpose of this experimental in vivo investigation was to evaluate the influence of modifying the implant surface by adding a monolayer of multi-phosphonate molecules on the de novo bone formation and osseointegration.

MATERIAL AND METHODS

The study was designed as an animal preclinical trial with intra-animal control and two healing periods, 2 and 8 weeks, to compare implants with an identical macro-design but with two different surfaces. Eight female Beagle dogs participated in the study. Control implants had a moderately rough surface combining sandblasting and acid etching; test implants had an additional monophosphonate layer covalently bonded to titanium. Histologic and radiographic (micro-CT) outcome variables were evaluated.

RESULTS

The first bone-to-implant contact (fBIC) was located more coronally for the test implants at the first (0.065 mm (95% CI = -0.82, 0.60)) and second healing milestones (0.17 mm (95% CI = -0.9, 0.55)). Most coronal BIC of the test implants displayed a higher percentage of osseointegration, +6.33% and +13.38% after 2 and 8 weeks, respectively; however, the differences were not statistically significant. The micro-CT examination did not show any BIC difference.

CONCLUSIONS

The monophosphonate layer coating demonstrated clinical, histological, and radiographic results similar to the control surface.

Histologic and histomorphometric evaluation of new zirconia-based ceramic dental implants: A preclinical study in dogs

OBJECTIVE

Healing of soft tissues and improvement of aesthetics have become major research objectives in implantology and renewed the interest for ceramics implants. The aim of this study was to evaluate the pre-clinical performance of screw-shaped sandblasted-etched implants processed from an innovative zirconia-based ceramic composite, in comparison to titanium.

METHODS

Twenty-four ceramic and twenty-four titanium screw-shaped sandblasted-etched dental implants were tested in a split-mouth design in six Beagle dogs. Surface topographies were investigated by confocal microscopy. Local tissue effects were evaluated at 4 and 13 weeks after implantation through histology. An ANOVA statistical analysis (5% risk; p < 0.05) was performed to compare peri-implant quantitative histomorphometric parameters on buccal and lingual sides, including Bone to Implant Contact (BIC) among test groups and time-periods.

RESULTS

Titanium and ceramic implants presented respectively moderate and minimal roughness. After 4 and 13 weeks, ceramic implants showed an inflammatory tissue response close to titanium implants. At both period of time there was no significant difference between the titanium and ceramic groups in terms of BIC values (mean ± SD) at the lingual or buccal sides or when combining buccal + lingual BIC values (respectively for titanium and ceramic, 68.4 ± 14.7 % and 75.0 ± 13.5 % at 4 weeks, and 92.0 ± 8.6 % and 86.1 ± 13.8 % at 13 weeks).

SIGNIFICANCE

Within the limits of the present study, it can be concluded that newly developed zirconia-based ceramic composite dental implants have similar biocompatibility and osseointegration to those observed in titanium implants. These pre-clinical results corroborate the potential for the use of these new zirconia-based ceramics in oral implantology.

Biomechanical analyses of one-piece dental implants composed of titanium, zirconia, PEEK, CFR-PEEK, or GFR-PEEK: Stresses, strains, and bone remodeling prediction by the finite element method

This work aimed to assess the biomechanics, using the finite element method (FEM), of traditional titanium Morse taper (MT) dental implants compared to one-piece implants composed of zirconia, polyetheretherketone (PEEK), carbon fiber-reinforced PEEK (CFR-PEEK), or glass fiber-reinforced PEEK (GFR-PEEK). MT and one-piece dental implants were modeled within a mandibular bone section and loaded on an oblique force using FEM. A MT implant system involving a Ti6Al4V abutment and a cp-Ti grade IV implant was compared to one-piece implants composed of cp-Ti grade IV, zirconia (3Y-TZP), PEEK, CFR-PEEK, or GFR-PEEK. Stress on bone and implants was computed and analyzed while bone remodeling prediction was evaluated considering equivalent strain. In comparison to one-piece implants, the traditional MT implant revealed higher stress peak (112 MPa). The maximum stresses on the one-piece implants reached ~80 MPa, regardless their chemical composition. MT implant induced lower bone stimulus, although excessive bone strain was recorded for PEEK implants. Balanced strain levels were noticed for reinforced PEEK implants of which CFR-PEEK one-piece implants showed proper biomechanical behavior. Balanced strain levels might induce bone remodeling at the peri-implant region while maintaining low risks of mechanical failures. However, the strength of the PEEK-based composite materials is still low for long-term clinical performance.

Evaluation of the Effects of ß-Adrenergic Receptor-Propranolol on Osseointegration of the Titanium Implants

ABSTRACT

This study aimed to investigate the effects of systemic propranol on the osseointegration of titanium implants. After the surgical insertion of titanium implants into the metaphyseal part of the tibial bone, the rats were randomly divided into 2 equal groups: the control (CNT) (n = 10) and propranol group (P) (n = 10); CNT: Rats received no further treatment during the 4 week experimental period after surgery. Rats received 10 mg/kg propranol in every day during the 4 week experimental period in PRP group after the surgical insertion of the implants. After the experimental period, the rats were euthanized, blood serum were collected to biochemical analysis and the implants and surrounding bone tissues were used for the histopathologic analysis. To analysis of the data between tests and controls student T test was used. There were no significant differences in the biochemical parameters (alcaline phosphatase, calcium, phosphor) of the groups (P > 0.05). Bone implant connection (BIC) ratios was detected higher in test animals compared with the controls (P < 0.05). Systemic propranolol may increases titanium implant osseointegration.