Healing at implants installed from ~ 70- to < 10-Ncm insertion torques: an experimental study in dogs

Influence on marginal bone levels at implants equipped with blades aiming to control the lateral pressure on the cortical bone. An experimental study in dogs

BACKGROUND

To avoid cortical compression, several implant systems have included in the protocol dedicated drills aimed at widening the cortical region of osteotomy. However, the manual execution of this operation does not guarantee the necessary precision. Hence, the present study aimed to determine the optimal size of the recipient site at the level of the alveolar crest in relation to the size of the coronal region of the implant to achieve the best healing result.

MATERIALS AND METHODS

Blades of different diameters were incorporated into the coronal part of the implant to prepare the cortical region of the mandibular alveolar bone crest in different dimensions in relation to the collar of the implant. The differences in diameter of the blades in relation to the collar of the implant were as follows: one control group, -175 μm, and three test groups, 0 μm, + 50 μm, or + 200 μm.

RESULTS

The marginal bone loss (MBL) at the buccal aspect was 0.7 mm, 0.5 mm, 0.2 mm, and 0.7 mm in the - 175 μm, 0.0 μm, + 50 μm, + 200 μm groups, respectively. The differences were statistically significant between group + 50 μm and control group - 175 μm (p = 0.019), and between + 50 μm and + 200 μm (p < 0.01) groups. The level of osseointegration at the buccal aspect was more coronally located in the test groups than in the control group, whereas the bone-to-implant contact percentage was higher in the + 50 μm and + 200 μm groups. However, these differences were not statistically significant.

CONCLUSIONS

The lowest bone crest resorption and highest levels of osseointegration were observed in the 0.0 μm and + 50 μm groups. The cortical region where the blades had performed their cutting action showed regular healing with perfect hard and soft tissues sealing in all the groups. Cortical blades gathered bone particles, particularly in the + 200 μm group, which were incorporated into the newly formed bone. The results from the present experiment provide support to the use of blades that produce a marginal gap of 50 μm after implant insertion.

The clinical application of customized 3D-printed porous tantalum scaffolds combined with Masquelet’s induced membrane technique to reconstruct infective segmental femoral defect

Purpose

This study mainly exams a novel treatment for infective segmental femoral defect, and we combined the 3D printed porous tantalum prosthesis and Masquelet’s induce membrane technique to reconstruct bone defect and discussed the clinical effect.

Method

The clinical research included 9 observational cases series, as a permanently implantation, the customized 3D-printed scaffolds that connected with an anatomical plate was implanted into the bone defect segment after successful formation of induced membrane, the clinical effect was evaluated by radiological exams and Paley’s bone union criteria.

Result

The personalized 3D-printed porous tantalum was, respectively, manufactured and used in 9 consecutive patients to reconstruct the infective segmental bone defect of femur, the mean defect length was 16.1 ± 2.8 cm, the mean length of follow-up was 16.9 ± 4.0 months, after 2 stage operation, there was no deep infections, refractures, sensorimotor disorder, vascular injury, ankylosis and recurrence of infection occurred in all cases. postoperative radiological exams shown stable internal fixation and osseointegration, and all these results were invariable during the follow-up time in all cases. All patients significantly obtained deformity correction and length of limb.

Conclusion

The customized 3D-printed porous tantalum prosthesis was an acceptable alternative treatment to the autogenous or allograft bone graft, the combination of the two techniques could achieve satisfactory reconstruct to infective broad bone defect in femur when other biological techniques were not suitable.

Validation of an implant stability measurement device using the percussion response: a clinical research study

Background

Several devices have been developed to measure implant-bone stability as an indicator of successful implant treatment; these include Osstell®, which measures the implant stability quotient (ISQ), and the more recent AnyCheck®, which relies on percussion for the implant stability test (IST). These devices make it possible to measure implant stability. However, no studies have compared the performance of AnyCheck® and Osstell® (i.e., IST and ISQ values) in clinical practice. Therefore, this study aimed to determine the correlation between primary and secondary implant stability using the Osstell® and AnyCheck® devices.

Methods

Ten patients (7 women; age [mean ± standard deviation]: 49.1 ± 13.3 years) with partially edentulous jaws who received a total of 15 implants were included. IST (AnyCheck®) and ISQ (Osstell®) values were measured immediately after implantation and at 1, 2, 3, 4, and 6 weeks post-implantation. Each measurement was performed three times, and the average value was used as the result. The correlation between measurements obtained using the two devices was determined using Spearman's rank correlation coefficient.

Results

The IST values ranged from 79.1 ± 2.87 to 82.4 ± 2.65. The ISQ values ranged from 76.0 ± 2.8 to 80.2 ± 2.35. Spearman's rank correlation coefficient was r = 0.64 immediately after implantation, r = 0.29 at 1 week, r = 0.68 at 2 weeks, r = 0.53 at 3 weeks, r = 0.68 at 4 weeks, and r = 0.56 at 6 weeks. A positive correlation was found in all cases, except at week 1 when the correlation was weak; the IST and ISQ values decreased the most during the first postoperative week and increased during the second week. The IST values were also slightly higher at all measurement points.

Conclusion

The ability to assess implant stability without removing the abutment during healing is essential for determining the timing of loading without the risk of bone resorption. The results of this study suggest that AnyCheck® is useful for determining primary and secondary implant stability.

Innovative Concepts and Recent Breakthrough for Engineered Graft and Constructs for Bone Regeneration: A Literature Systematic Review

Background: For decades, regenerative medicine and dentistry have been improved with new therapies and innovative clinical protocols. The aim of the present investigation was to evaluate through a critical review the recent innovations in the field of bone regeneration with a focus on the healing potentials and clinical protocols of bone substitutes combined with engineered constructs, growth factors and photobiomodulation applications. Methods: A Boolean systematic search was conducted by PubMed/Medline, PubMed/Central, Web of Science and Google scholar databases according to the PRISMA guidelines. Results: After the initial screening, a total of 304 papers were considered eligible for the qualitative synthesis. The articles included were categorized according to the main topics: alloplastic bone substitutes, autologous teeth derived substitutes, xenografts, platelet-derived concentrates, laser therapy, microbiota and bone metabolism and mesenchymal cells construct. Conclusions: The effectiveness of the present investigation showed that the use of biocompatible and bio-resorbable bone substitutes are related to the high-predictability of the bone regeneration protocols, while the oral microbiota and systemic health of the patient produce a clinical advantage for the long-term success of the regeneration procedures and implant-supported restorations. The use of growth factors is able to reduce the co-morbidity of the regenerative procedure ameliorating the post-operative healing phase. The LLLT is an adjuvant protocol to improve the soft and hard tissues response for bone regeneration treatment protocols.

Mechanical Behaviour and Primary Stability of a Self-Condensing Implant: A Laboratory Critical Simulation of a Severe Maxillary Atrophy on Polyurethane Lamina

Background: Posterior maxillary atrophies could emerge after the loss of teeth, trauma, infections, or lesions that often require regenerative approaches. In these critical conditions, the achievement of implant primary stability represents a clinical challenge in the operative practice. Therefore, a two-stage approach is often preferred with a delay of the rehabilitation time and a consistent increasing of the biological and the operative costs. The aim of this study was to evaluate the mechanical behaviour of a self-condenser implant compared to a standard implant in a critical simulation on different thicknesses and densities of polyurethane lamina. Materials and methods: A total of two implant models were tested: a self-condensing device (test) and a standard implant (control). The study evaluated the insertion torque and the pull-out strength values of the test and control implants inserted in different sizes (1, 2, and 3 mm) and density polyurethane lamina (10, 20, and 30 pcf) for a total of 320 experimental sites. Results: In total, 320 experimental sites were produced in the polyurethane samples. A statistically significant difference of insertion and pull-out torque values between the test and control Implants was found in the different bone densities (p < 0.05). The insertion and pull-out torque values were always higher for the test implants in all experimental conditions. In all bone densities, the insertion torque values were higher than the pull-out torque values. The self-condenser dental implant design evaluated in this in vitro study showed a high level of stability in all experimental conditions. Conclusions: The test implant could represent a useful tool for a one-stage surgical approach in the presence of limited residual native bone as an alternative to a delayed technique.

Immunity Profiling of COVID-19 Infection, Dynamic Variations of Lymphocyte Subsets, a Comparative Analysis on Four Different Groups

Background: A novel coronavirus (SARS-CoV-2)-induced pneumonia (COVID-19) emerged in December 2019 in China, spreading worldwide. The aim of the present investigation was to evaluate the immunological response and the clinical subset of peripheral lymphocyte subset alteration in COVID-19 infection. Methods: the study was conducted on four different clinical groups (n = 4; total n = 138). Each individual was assigned to different groups based on specific criteria evaluated at the admission such as fever, dyspnea, arterial blood gas analysis (ABG), oral-nasopharyngeal swab/RT-PCR, and thoracic CT-scan. Treatment was performed only after blood samples were collected from each patient (PP and PP) at day 1. The blood samples were analyzed and tested the same day (CBC and Flowcytometry). The positive–positive group (PP n = 45; F = 18/ M = 27; median age = 62.33), comprised individuals affected by COVID-19 who showed fever, dyspnea (ABG = pO2 < 60), confirmed positive by oral-nasopharyngeal swab/RT-PCR and with CT-scan showing ground-glass opacities. The negative–positive (NP; n = 37; F = 11/M = 26; median age = 75.94) or “COVID-like” group comprised individuals with fever and dyspnea (ABG = pO2 < 60), who tested negative to nasopharyngeal swab/RT-PCR, with CT-scans showing ground-glass opacities in the lungs. The negative–affected group (NA; n = 40; F = 14/M = 26; median age = 58.5) included individuals negative to COVID-19 (RT-PCR) but affected by different chronic respiratory diseases (the CT-scans didn’t show ground-glass opacities). Finally, the negative–negative group (NN; n = 16; F = 14/M = 2) included healthy patients (NN; n = 16; median age = 42.62). Data and findings were collected and compared. Results: Lymphocytes (%) cells showed a decline in COVID-19 patients. The subsets showed a significant association with the inflammatory status in COVID-19, especially with regard to increased neutrophils, T-killer, T-active, T-suppressor, and T-CD8+CD38+ in individuals belong to the either COVID-19 and Covid-like NP group. Conclusions: Peripheral lymphocyte subset alteration was associated with the clinical characteristics and progression of COVID-19. The level of sub-set cells T-lymphocytes (either high or low) and B-lymphocytes could be used as an independent predictor for COVID-19 severity and treatment efficacy.

COVID-19 Infection in Children, Infants and Pregnant Subjects: An Overview of Recent Insights and Therapies

BACKGROUND

The SARS-CoV-2 pandemic has involved a severe increase of cases worldwide in a wide range of populations. The aim of the present investigation was to evaluate recent insights about COVID-19 infection in children, infants and pregnant subjects.

METHODS

a literature overview was performed including clinical trials, in vitro studies, reviews and published guidelines regarding the present paper topic. A descriptive synthesis was performed to evaluate recent insights and the effectiveness of therapies for SARS-CoV-2 infection in children, infants and pregnant subjects.

RESULTS

Insufficient data are available regarding the relationship between COVID-19 and the clinical risk of spontaneous abortion and premature foetus death. A decrease in the incidence of COVID-19 could be correlated to a minor expression of ACE2 in childrens' lungs. At present, a modulation of the dose-effect posology for children and infants is necessary.

CONCLUSIONS

Pregnant vertical transmission has been hypothesised for SARS-CoV-2 infection. Vaccines are necessary to achieve mass immunity for children and also pregnant subjects.

An In Vitro Analysis on Polyurethane Foam Blocks of the Insertion Torque (IT) Values, Removal Torque Values (RTVs), and Resonance Frequency Analysis (RFA) Values in Tapered and Cylindrical Implants

Background: Several different dental implant microgeometries have been investigated in the literature for use in low-density bone sites. The polyurethane solid rigid blocks represent an optimal in vitro study model for dental implants, because their composition is characterized by symmetrical linear chains of monomers of hexa-methylene sequences producing a self-polymerization process. The aim of the present investigation was to evaluate the primary stability of cylindrical and tapered implants positioned into low-density polyurethane solid rigid blocks. Materials and Methods: Two different macrogeometries, cylindrical (4 mm diameter and 10 mm length) and tapered dental implants (4.20 mm diameter and 10 mm length), were investigated in the present study. The implants were inserted into 10 PCF and 20 PCF polyurethane blocks, with and without an additional cortical layer. The insertion torque (IT) values, the removal torque values (RTVs), and the resonance frequency analysis (RFA) values were measured and recorded. Results: A total of 80 sites were tested, and a significant increased primary stability (PS) was detected in favour of tapered dental implants when compared to cylindrical implants in all experimental conditions (p < 0.05). Higher IT, RT, and RFA values were measured in tapered implants in 10 and 20 PCF polyurethane blocks, both with and without the additional cortical layer. Conclusions: Both implants showed sufficient primary stability in poor density substrates, while, on the other hand, the tapered microgeometry showed characteristics that could also lead to clinical application in low-density posterior maxillary sites, even with a drastically decreased bone cortical component.

The Influence of the Implant Macrogeometry on Insertion Torque, Removal Torque, and Periotest Implant Primary Stability: A Mechanical Simulation on High-Density Artificial Bone

Background: The primary stability is a determinant clinical condition for the success of different dental implants macro-design in different bone density using a validated and repeatable in vitro technique employing solid rigid polyurethane blocks. Materials and Methods: Five implants 3.8 × 13 mm2 for each macro-design (i.e., IK—tapered; IC—cylindric; and IA—active blade shape) were positioned into 20- and 30- pounds per cubic foot (PCF) polyurethane blocks. Bucco-lingual (BL) and mesial-distal (MD) implant stability quotient score (ISQ) was assessed by resonance frequency analysis while, insertion/removal torques were evaluated by dynamometric ratchet. Results: IC implants shown better primary stability in terms of ISQ compared to IA and IK in lower density block (20 PCF), while IK was superior to IA in higher density (30 PCF). IC shown higher removal torque in 30-PCF compared to IA and IC. Conclusions: The study effectiveness on polyurethane artificial bone with isotropic symmetry structure showed that the implants macro-design might represent a key factor on primary stability, in particular on low-density alveolar bone. Clinicians should consider patients features and implant geometry during low-density jaws rehabilitation. Further investigations are needed to generalize these findings.

Survival Rate of Zygomatic Implants for Fixed Oral Maxillary Rehabilitations: A Systematic Review and Meta-Analysis Comparing Outcomes between Zygomatic and Regular Implants

Background: Zygomatic implants have been proposed alone or in combination with premaxillary conventional implants for severe resorbed maxillary atrophy rehabilitation. The aim of the present investigation was to evaluate through a qualitative systematic review and meta-analysis the survival rate of zygomatic implants in conjunction with regular fixtures for maxillary rehabilitation. Methods: The article screening was conducted on the PubMed/Medline and EMBASE electronic databases according to the “Preferred Reporting Items for Systematic Reviews and Meta-Analyses” (PRISMA) guidelines. The scientific papers were included for qualitative analysis and risk-of-bias evaluation. Only the papers that included rehabilitation with zygomatic implants in combination with regular implants were considered for the meta-analysis comparative evaluation of the implant survival rate. Results: The paper search screened a total of 137 papers. After the initial screening, a total of 32 articles were considered for the qualitative analysis. There was a similar implant survival rate between zygomatic and premaxilla regular implants (p = 0.02; Z: 2.26). Conclusions: Zygomatic and conventional implants showed a high long-term survival rate for fixed maxillary rehabilitations, but few included studies reported the marginal bone loss after loading. Further studies are necessary to evaluate the pattern of marginal bone loss between zygomatic and conventional implants after long-term functional loading.

The Effectiveness of Osseodensification Drilling Protocol for Implant Site Osteotomy: A Systematic Review of the Literature and Meta-Analysis

Many different osteotomy procedures has been proposed in the literature for dental implant site preparation. The osseodensification is a drilling technique that has been proposed to improve the local bone quality and implant stability in poor density alveolar ridges. This technique determines an expansion of the implant site by increasing the density of the adjacent bone. The aim of the present investigation was to evaluate the effectiveness of the osseodensification technique for implant site preparation through a literature review and meta-analysis. The database electronic research was performed on PubMed (Medline) database for the screening of the scientific papers. A total of 16 articles have been identified suitable for the review and qualitative analysis—11 clinical studies (eight on animals, three on human subjects), four literature reviews, and one case report. The meta-analysis was performed to compare the bone-to-implant contact % (BIC), bone area fraction occupied % (BAFO), and insertion torque of clockwise and counter-clockwise osseodensification procedure in animal studies. The included articles reported a significant increase in the insertion torque of the implants positioned through the osseodensification protocol compared to the conventional drilling technique. Advantages of this new technique are important above all when the patient has a strong missing and/or low quantity of bone tissue. The data collected until the drafting of this paper detect an improvement when the osseodensification has been adopted if compared to the conventional technique. A significant difference in BIC and insertion torque between the clockwise and counter-clockwise osseodensification procedure was reported, with no difference in BAFO measurements between the two approaches. The effectiveness of the present study demonstrated that the osseodensification drilling protocol is a useful technique to obtain increased implant insertion torque and bone to implant contact (BIC) in vivo. Further randomized clinical studies are required to confirm these pieces of evidence in human studies.

Synthetic Scaffold/Dental Pulp Stem Cell (DPSC) Tissue Engineering Constructs for Bone Defect Treatment: An Animal Studies Literature Review

Background: Recently a greater interest in tissue engineering for the treatment of large bone defect has been reported. The aim of the present systematic review and meta-analysis was to investigate the effectiveness of dental pulp stem cells and synthetic block complexes for bone defect treatment in preclinical in vivo articles. Methods: The electronic database and manual search was conducted on Pubmed, Scopus, and EMBASE. The papers identified were submitted for risk-of-bias assessment and classified according to new bone formation, bone graft characteristics, dental pulp stem cells (DPSCs) culture passages and amount of experimental data. The meta-analysis assessment was conducted to assess new bone formation in test sites with DPSCs/synthetic blocks vs. synthetic block alone. Results: The database search identified a total of 348 papers. After the initial screening, 30 studies were included, according to the different animal models: 19 papers on rats, 3 articles on rabbits, 2 manuscripts on sheep and 4 papers on swine. The meta-analysis evaluation showed a significantly increase in new bone formation in favor of DPSCs/synthetic scaffold complexes, if compared to the control at 4 weeks (Mean Diff: 17.09%, 95% CI: 15.16–18.91%, p < 0.01) and at 8 weeks (Mean Diff: 14.86%, 95% CI: 1.82–27.91%, p < 0.01) in rats calvaria bone defects. Conclusion: The synthetic scaffolds in association of DPSCs used for the treatment of bone defects showed encouraging results of early new bone formation in preclinical animal studies and could represent a useful resource for regenerative bone augmentation procedures

Scientific Trends in Clinical Research on Zirconia Dental Implants: A Bibliometric Review

Background: The clinical use of zirconia implants has been shown to increase steadily due to their biological, aesthetic, and physical properties; therefore, this bibliometric study aimed to review the clinical research and co-authors in the field of zirconia dental implant rehabilitation. Methods: We searched Scopus and Web of Science databases using a comprehensive search strategy to 5 October 2020, and independently paired reviewers who screened studies, and collected data with inclusion criteria restricted to clinical research only (either prospective or retrospective). Data on article title, co-authors, number of citations received, journal details, publication year, country and institution involved, funding, study design, marginal bone loss, survival rate, failure, follow-up, and the author’s bibliometric data were collected and evaluated. Results: A total of 29 clinical studies were published between 2008 and 2020 as 41.4% were prospective cohort studies and 48.3% originated from Germany. Most of the included studies had been published in Clinical Oral Implant Research (n = 12), and the most productive institution was the Medical Center of University of Freiburg. The author with the largest number of clinical studies on zirconia implants was Kohal R.J. (n = 10), followed by Spies B.C. (n = 8). Conclusions: This study revealed that zirconia implants have been more prominent in the last ten years, which is a valuable option for oral rehabilitation with marginal bone loss and survival rate comparable to titanium dental implants.