The Effects of Superficial Roughness and Design on the Primary Stability of Dental Implants

Analysis of osseointegration of implants with macrogeometries with healing chambers: a randomized clinical trial

BACKGROUND

To verify the influence of macrogeometry with healing chambers on the osseointegration of dental implants by analyzing implant stability quotient (ISQ) and evaluate the correlation between insertion torque and ISQ insertion with different macrogeometries.

METHODS

In total, 26 implants were installed in the posterior mandible of eight patients with sufficient bone height for the installation of implants measuring 3.5 mm in diameter and 9.0 mm in length. The implants were categorized according to two types of macrogeometry: a test group (GT) with 13 conical implants with healing chambers and a control group (GC) with 13 conical implants with conventional threads. To insert the implants, a bone drilling protocol was used up to a diameter of 3 mm with the last helical bur. The insertion torque of the implants was evaluated, followed by the measurement of ISQ at 0 (T-0), 7 (T-7), 14 (T-14), 21 (T-21), 28 (T-28), and 42 (T-42) days.

RESULTS

The mean insertion torque was 43 Ncm in both groups, without a significant difference. Moreover, no significant difference in the ISQ values was found between the groups at different time points (p > 0.05), except at T-7 (GT = 69.87±1.89 and GC = 66.48±4.49; p = 0.01). Although there was no significant difference, ISQ median values were higher in the GT group than GC group at 28 days (GT = 67.98 and GC = 63.46; p = 0.05) and 42 days (GT = 66.12 and GC = 60.33; p = 0.09). No correlation was found between the insertion torque and ISQ insertion (p > 0.05).

CONCLUSION

Furthermore, implants with a 3.5 mm diameter macrogeometry, with or without healing chambers, inserted with a drilling protocol up to 3 mm in diameter of the last helical bur, led to a similar secondary stability, with no difference in ISQ values. Although, implants with healing chamber demonstrates ascending values in the graph of ISQ, having a trend of faster osseointegration than implants without healing chambers. Both macrogeometries provide a similar primary stability to implants.

TRIAL REGISTRATION

This study was registered retrospectively in ReBec (brazilian registry of clinical trials) under the number RBR-96n5×69, on the date of 19/06/2023.

Correlation between Implant Surface Roughness and Implant Stability: A Systematic Review

The aim of this study was to find in the literature data on the relationship between implant surface roughness and implant stability achieved, from the time of placement to three months afterward, to help us to know what type of surface roughness is more favorable to guarantee implant stability and osseointegration. A systematic review was conducted in accordance with the PRISMA 2020 (Preferred Reporting Items for Systematic Review and Meta-analysis) statement, and the protocol was registered on the Open Science Framework. The specific inclusion and exclusion criteria were selected using the PICOS framework. The databases Medline (PubMed), Scopus, the Web of Science and The Cochrane Library were searched up to October 2023. The selection of studies and data extraction were conducted by two independent reviewers. The review included a total of 11 studies. A total of 1331 dental implant placements were identified. Two of the eleven selected studies were on humans in vivo, eight were on animals in vivo, and one was on animals in vitro. A statistically significant correlation between surface roughness and implant stability as measured by resonance frequency analysis (RFA) was not identified in ten of the eleven selected studies. It appears that there is no correlation between primary stability and the degree of implant roughness. However, there appears to be a correlation between the roughness of the implant and the degree of osseointegration, as indicated by bone-implant contact values. This correlation is more closely related to secondary stability. The great methodological variability makes it difficult to compare data and draw conclusions, so it would be desirable to agree on a common methodology to help draw appropriate conclusions from published studies.

A comparison of transforaminal lumbar interbody fusion (TLIF) cage material on fusion rates: A systematic review and network meta-analysis

Background

A wide variety of materials are used for lumbar interbody fusion, but there is no unified consensus on the superiority of one material over another. The aim of this systematic review and network meta-analysis (NMA) is to compare and rank the various TLIF interbody materials based on fusion rates.

Methods

We queried PubMed, EMBASE and Scopus from inception until August 2023, in which 2135 studies were identified. Inclusion criteria were applied based on the PRISMA guidelines. The fusion assessment employed the Bridwell's criteria with a length of follow-up of at least 12 months. The NMA was conducted to compare multiple approaches from multiple studies using the frequentist framework with STATA16.

Results

In total, 13 TLIF studies involving 1919 patients with 1981 lumbar interbody levels fulfilled our eligibility criteria. Seven different cage materials were utilized: polyetheretherketone (PEEK, as the reference), allograft, autograft, PEEK with titanium coating (TiPEEK), titanium, carbon/carbon fiber reinforced polymer (CFRP) and 3D-printed titanium. The average patient age was 60.9 (SD = 7.5) years old. When compared to PEEK, the other six materials did not have a significantly different rate of lumbar fusion. However, the SUCRA number of the 3D-printed titanium, TiPEEK, Ti, allograft, autograft, CFRP, and PEEK were 0.8, 0.6, 0.5, 0.5, 0.4, 0.4, and 0.3 consecutively.

Conclusions

Based on a network meta-analysis within the confines of our clinical study, 3D-printed titanium interbody cage may promote the highest success rate of fusion while PEEK may be the material with the least success rate of fusion in TLIF.

Tribocorrosion of 3D printed dental implants: An overview

With the advancements in dental science and the growing need for improved dental health, it has become imperative to develop new implant materials which possess better geometrical, mechanical, and physical properties. The oral environment is a corrosive environment and the relative motion between the teeth also makes the environment more hostile. Therefore, the combined corrosion and tribology commonly known as tribocorrosion of implants needs to be studied. The complex shapes of the dental implants and the high-performance requirements of these implants make manufacturing difficult by conventional manufacturing processes. With the advent of additive manufacturing or 3D-printing, the development of implants has become easy. However, the various requirements such as surface roughness, mechanical strength, and corrosion resistance further make the manufacturing of implants difficult. The current paper reviews the various studies related to3D-printed implants. Also, the paper tries to highlight the role of 3D-Printing can play in the area of dental implants. Further studies both experimental and numerical are needed to devise optimized conditions for 3D-printing implants to develop implants with improved mechanical, corrosion, and biological properties.

Primary Stability of Implants Inserted into Polyurethane Blocks: Micro-CT and Analysis In Vitro

The approach employed for the site preparation of the dental implant is a variable factor that affects the implant's primary stability and its ability to integrate with the surrounding bone. The main objective of this in vitro study is to evaluate the influence of different techniques used to prepare the implant site on the primary stability of the implant in two different densities of artificial bone.

MATERIALS AND METHODS

A total of 150 implant sites were prepared in rigid polyurethane blocks to simulate two distinct bone densities of 15 pounds per cubic foot (PCF) and 30 PCF, with a 1-mm-thick simulated cortex. The implant sites were equally distributed among piezoelectric surgery (PES), traditional drills (TD), and black ruby magnetic mallet inserts (MM). Two methods have been employed to evaluate the implant's primary stability, Osstell and micro-tomography.

RESULTS

In the present study, we observed significant variations in the implant stability quotient (ISQ) values. More precisely, our findings indicate that the ISQ values were generally higher for 30 PCF compared to 15 PCF. In terms of the preparation technique, PES exhibited the greatest ISQ values, followed by MM, and finally TD. These findings corresponded for both bone densities of 30 PCF (PES 75.6 ± 1.73, MM 69.8 ± 1.91, and TD 65.8 ± 1.91) and 15 PCF (PES 72.3 ± 1.63, MM 62.4 ± 1.77, and TD 60.6 ± 1.81). By utilizing Micro-CT scans, we were able to determine the ratio of the implant occupation to the preparation site. Furthermore, we could calculate the maximum distance between the implant and the wall of the preparation site. The findings demonstrated that PES had a higher ratio of implant to preparation site occupation, followed by TD, and then the MM, at a bone density of 30 PCF (PES 96 ± 1.95, TD 94 ± 1.88, and MM 90.3 ± 2.11). Nevertheless, there were no statistically significant differences in the occupation ratio among these three approaches in the bone density of 15 PCF (PES 89.6 ± 1.22, TD 90 ± 1.31, and MM 88.4 ± 1.17). Regarding the maximum gap between the implant and the site preparation, the smallest gaps were seen when TD were used, followed by MM, and finally by PES, either in a bone density 15 PCF (PES 318 ± 21, TD 238 ± 17, and MM 301 ± 20 μm) or in a bone density 30 PCF (PES 299 ± 20, TD 221 ± 16, and MM 281 ± 19 μm). A statistical analysis using ANOVA revealed these differences to be significant, with p-values of < 0.05.

CONCLUSION

The outcomes of this study indicate that employing the PES technique and osteo-densification with MM during implant insertion may enhance the primary stability and increase the possibility of early implant loading.

Conventional Versus Osseodensification Drilling in the Narrow Alveolar Ridge: A Prospective Randomized Controlled Trial

Background Conventionally, undersized osteotomies were used to increase initial bone-to-implant contact to achieve primary stability in implantology. This is particularly evident in regions with low bone density. The potential for severe bone compression and ischemia poses a challenge to secondary stability. Instead, lateral bone compaction is caused by the idea of osseodensification. Research on the potential benefits of this method for narrow ridges is lacking. This study aimed to determine if the osseodensification drilling technique affects primary stability and how much the alveolar ridge expands following implant site preparation. Methodology A total of 30 participants aged 20 to 80 years were included in this randomized controlled clinical investigation. Each participant was randomly assigned to one of the following two groups: one that received standard drill preparation, and another that received osseodensification drill preparation. Implant stability using implant stability quotient values, crest width, apical width (5 mm from crest), and bone density were assessed both before and after six months using cone-beam computed tomography. Results Osseodensification impacted the width at the apex (5 mm from the crest) and radiographic bone density, adding to the quality, but did not affect implant stability and crestal width after osseointegration. The mean difference in conventional and osseodensification groups was 0.46 and 0.68 mm, respectively, concerning the crestal width. Moreover, the mean difference was 0.74 and 0.58 mm for conventional and osseodensification groups, respectively, concerning the width at the apex (5 mm from the crest). Conclusions This study demonstrates that the osseodensification process increased both the radiographic bone density and the width at the apex, demonstrating that osseodensification drilling techniques allow for the placement of implants with larger diameters in narrow alveolar ridges.

Correlation Between Acquisition of Dental Implant Stability and Hounsfield Units at Dental Implant Placement

Alveolar bone quality at the implantation site affects the initial stability of dental implant treatment. However, the relationship between bone quality and osseointegration has yet to be evaluated. Herein, we aimed to investigate the effect of bone quality on dental implant stability in osseointegration formation changes. Patients underwent computed tomography imaging before dental implantation at the posterior. Hounsfield units were measured at the platform, middle, and tip sites. Implant stability was measured using resonance frequency analysis immediately and at 3 months postoperatively, in which the difference in implant stability quotients (ISQ) was defined as the change between primary and secondary fixation. In multiple regression analysis, the dependent variable was the change between the immediate and secondary fixations. We included 81 implants that conformed to the criteria. Primary fixation yielded the following results: R2 = 0.117, F = 2.529, and P = .047. The difference between the maxilla and mandible of the implantation site (P = .02) and the platform-site Hounsfield units (P = .019) were identified as significant factors. The following results were obtained regarding the change between the immediate and secondary fixation: R2 = 0.714, F = 40.964, and P < .001. The difference between diameter (P = .008) and the immediate ISQ (P < .001) were identified as significant factors. Overall, the bone quality of the implantation site affected initial fixation; however, it had limited effect on secondary fixation. Our findings clarified the period where bone quality affects dental implant treatment and is expected to advance dental implant treatment.

Role of finite element analysis for selection of single point fixation in zygomaticomaxillary complex fracture

BACKGROUND

One-point fixation was superior to the two and three-points fixation in minimally displaced zygomaticomaxillary complex (ZMC) fracture regarding the cost, invasiveness, scaring, number of wounds, and operation time. Accordingly, this study aimed to predict which one-point fixation is the most stable in managing minimally displaced ZMC fracture.

MATERIAL & METHODS

This study simulated the different one-point fixation approaches on three ZMC models after fracture reduction and application of all forces exerted on the fractured area. The findings were represented as stress impact on the ZMC fracture and plating system as well as the inter-fragments micro-motion.

RESULTS

The von misses stresses of plates for the zygomaticofrontal, infra-orbital rim, and zygomaticomaxillary buttress model were (66.508, 1.285, and1.16 MPa) respectively. While the screws' von misses for the infraorbital rim, zygomaticofrontal, and zygomaticomaxillary buttress models were (13.8, 4.05, and 1.60 MPa) respectively. Whereas, the maximum principles stress at zygomaticofrontal, zygomaticomaxillary buttress, and infraorbital rim models were (37.03, 37.01, and 34.46 MPa) respectively. In addition, the inter-fragment micro-motion for zygomaticomaxillary buttress, infraorbital rim, and zygomaticofrontal models were (0.26, 0.25, and 0.15 mm) respectively.

CONCLUSION

One-point fixation at zygomaticomaxillary buttress is the preferred point because it is exposed to low stresses, and the inter-fragment micro-motion is within the approved limit with the elements in the same direction of fixation which indicates the rigid fixation. In addition, it is less palpable and scarless.

TRIAL REGISTRATION

clinical trial.gov (NCT05819372) at 19/04/2023.

A Comparison of Conical and Cylindrical Implants Inserted in an In Vitro Post-Extraction Model Using Low-Density Polyurethane Foam Blocks

Combining tooth extraction and implant placement reduces the number of surgical procedures that a patient must undergo. Thus, the present study aimed to compare the stability of two types of conical implants (TAC and INTRALOCK) and another cylindrical one (CYROTH), inserted with a range of angulation of 15-20 degrees in low-density polyurethane blocks (10 and 20 pounds per cubic foot, PCF) with or without a cortical lamina (30 PCF), which potentially mimicked the post-extraction in vivo condition. For this purpose, a total of 120 polyurethane sites were prepared (10 for each implant and condition) and the Insertion Torque (IT), Removal Torque (RT), and Resonance Frequency Analysis (RFA) were measured, following a Three-Way analysis of variance followed by Tukey's post hoc test for the statistical analysis of data. The IT and RT values registered for all implant types were directly proportional to the polyurethane density. The highest IT was registered by INTRALOCK implants in the highest-density block (32.44 ± 3.28 Ncm). In contrast, the highest RFA, a well-known index of Implant Stability Quotient (ISQ), was shown by TAC implants in all clinical situations (up to 63 ISQ in the 20 PCF block without the cortical sheet), especially in lower-density blocks. Although more pre-clinical and clinical studies are required, these results show a better primary stability of TAC conical implants in all tested densities of this post-extraction model, with a higher ISQ, despite their IT.

Comparison of Implant Surgery Methods of Cortical Tapping and Cortical Widening in Bone of Various Density: A Three-Dimensional Finite Element Study

PURPOSE

The primary stability of a dental implant is critical for successful osseointegration during immediate loading. The cortical bone should be prepared to achieve enough primary stability, but not overcompressed. In this study, we investigated the stress and strain distribution in the bone around the implant induced by the occlusal force applied during immediate loading at various bone densities by the FEA method to compare cortical tapping and widening surgical techniques.

MATERIALS AND METHODS

A three-dimensional geometrical model of a dental implant and bone system was created. Five types of bone density combination (D111, D144, D414, D441 and D444) were designed. Two surgical methods-cortical tapping and cortical widening-were simulated in the model of the implant and bone. An axial load of 100 N and an oblique load of 30 N were applied to the crown. The maximal principal stress and strain were measured for comparative analysis of the two surgical methods.

RESULTS

Cortical tapping showed lower maximal stress of bone and maximal strain of bone than cortical widening when dense bone was located around the platform, regardless of the direction of the applied load.

CONCLUSIONS

Within the limitations of this FEA study, it can be concluded that cortical tapping is biomechanically more advantageous to the implants under occlusal force during immediate loading, especially when the bone density around the platform is high.

Osseointegration in relation to drilling speed in the preparation of dental implants sites: A systematic review

STATEMENT OF PROBLEM

The drilling speed used for preparing dental implants may affect bone-implant contact (BIC), implant stability quotient (ISQ), and bone area fraction occupancy (BAFO). Different rotational speeds and the presence or absence of irrigation during site preparation have been investigated, but an established protocol for achieving the best osseointegration results is lacking.

PURPOSE

The purpose of this systematic review was to investigate the influence of drill rotational speed on bone drilling for dental implant placement and its relationship with osseointegration.

MATERIAL AND METHODS

This review included the preferred reporting items for systematic reviews and meta-analyses (PRISMA) and was registered in the international prospective register of systematic reviews (PROSPERO) database. Electronic searches were performed in the MEDLINE (PubMed), Scopus, Science Direct, and Embase databases. The risk of bias was analyzed by using the systematic review center for laboratory animal experimentation (SYRCLE).

RESULTS

A total of 1282 articles were found, and after removing duplicates and applying the eligibility criteria to in vivo articles on animals that addressed drilling speed and its relationship to osseointegration, 8 articles were selected for analysis. Of these, 5 articles showed no statistical differences, and 3 others showed significantly better osseointegration results by analyzing the parameters of BIC, BAFO, ISQs, and pull-out forces (PoFs). In all selected articles, high-speed drilling was performed with irrigation.

CONCLUSIONS

Although drilling speed seems to affect bone perforation, no definitive protocol was found in the literature consulted. The results vary depending on the combination of different factors, including bone type, irrigation, and drilling speed.

Analysis of Bone Stress and Primary Stability of a Dental Implant Using Strain and Torque Measurements

Introduction

The consensus among researchers is that early failure of dental implants is due to the lack of primary stability and compressive stress on the peri-implant bone that exceeds the physiological tolerance.

Objective

The objective of this work is to propose a new methodology to quantify bone stress during dental implant insertion and to correlate it with primary stability.

Materials and Methods

Titanium dental implants with a diameter of 3.75 mm were inserted in a 3.35 mm hole of a synthetic bone of polyurethane (PU) foam with a density of 20 PCF (0.32 g/cm³). During insertion, the insertion torque was measured with a digital torque meter and the bone strain was measured with strain gages located at 2, 4, 6, 8, and 10 mm from the coronal region.

Results

The tests showed that the compressive strain is maximum in the third coronal region and decreases in the apical direction. The data also showed that there is a relationship between strain, insertion torque, and the primary stability of dental implants.

Conclusion

The stress and strain on the bone progressively decreased from the coronal to the apical third. The maximum compressive stress (0.42 MPa) during insertion of the implant did not exceed bone strength. Insertion of 3.75 mm implants in type D2 bone with a 3.35 mm hole provides adequate primary stability without excessive compression of the bone.

Clinical Significance

For the implant-bone combination used in the present study, the compressive stress generated during implant insertion did not exceed the physiological limit of cortical and medullary bone to the point of impairing osseointegration.

Hybrid Funnel Technique: A Novel Approach for Implant Site Preparation: A Pilot Study

(1) Background: Different techniques and tools have been developed for implant site preparation. In this clinical scenario, Hybrid Funnel Technique (HFT), a novel osteotomy procedure, has been proposed. (2) Aim: The aim of this retrospective observational study was to consider the different responses to compression of the histological bony compartments (cancellus and cortical). HFT involves the use of multiple drills for the cortical layer preparation and of an osteotome for the osteocompaction of the cancellous bone. (3) Materials and Methods: Following computer-supported implant planning and guided surgery, 10 osteotomies with HFT were performed and 10 implants with the same length and diameter were placed in seven healthy and no daily smoking patients. Periapical X-ray and intraoral photographs were performed at baseline and after 12 months of follow-up to evaluate marginal bone level (MBL) changes and aesthetic results obtained from implant prosthetic rehabilitation. (4) Results: At 1 year of follow-up, 100% of the implants were successfully integrated, MBL change mean value was 0.17 mm ± 0.21. No differences in terms of MBL were noted between thin and thick biotypes. Pink esthetic score (PES) and white esthetic score (WES), assessed one year after definitive restoration placement, were 7.5 ± 2.3 and 8.5 ± 1.1, respectively. (5) Conclusions: Based on the findings of this preliminary clinical study, HFT has led to stability of peri-implant tissues and could represent a reliable technique for surgical preparation of the implant site.

Titanium alkalinization improves response of osteoblasts to zoledronic acid

This investigation is aimed to determine the effect of the modification of titanium surface with NaOH on the metabolism of osteoblasts treated with zoledronic acid (ZA). Machined and NaOH-treated titanium disks were used. Surfaces were characterized by scanning electron microscopy, confocal microscopy, and x-ray photoelectron spectroscopy (XPS) analysis. Human osteoblasts were seeded onto the disks. After 24 h, cells were treated with ZA at 5 μM for 7 days. At this point, cell viability, collagen synthesis, total protein production, alkaline phosphatase activity, and mineral nodule deposition were assessed. The results of surface roughness were descriptively and statistically analyzed (t-Student), while the XPS results were qualitatively described. Cell metabolism data were analyzed by the analysis of variance two-way and Tukey tests at a 5% significance level. The results demonstrated that NaOH-treatment increased surface roughness (p < .05) and confirmed the presence of sodium titanate and a pH switch on the NaOH-treated disks. This modification also resulted in higher cell viability, collagen synthesis, total protein production, and alkaline phosphatase by osteoblasts when compared to cells seeded onto machined disks (p < 0.05). In the presence of ZA, all cellular metabolism and differentiation parameters were significantly reduced for cells seeded on both surfaces (p < 0.05); however, the cells seeded onto modified surfaces showed higher values for these parameters, except for mineral nodule deposition (p < 0.05). NaOH modification improved cell adhesion and metabolism of osteogenic cells even in the presence of ZA. The surface modification of titanium with NaOH solution may be an interesting strategy to improve metabolism and differentiation of osteoblasts and accelerate osseointegration process, mainly for tissues exposed to ZA.

Immediately provisionalized tapered conical connection implants for single-tooth restorations in the maxillary esthetic zone: a 5-year prospective single-cohort multicenter analysis

Objectives

This open, single-cohort, multicenter, prospective study investigated the efficacy of immediately provisionalized tapered conical connection implant for single-tooth restorations in the anterior and premolar regions of the maxilla after 5 years of function.

Materials and methods

All implants were placed in healed sites and immediately provisionalized. MBLs, soft-tissue parameters, and oral-health impact profile (OHIP) were evaluated at implant insertion, 6, 12, 24, 36, and 60 months. Paired Wilcoxon signed-rank tests and Kaplan–Meier survival analysis was used for statistical and implant survival/success analyses, respectively.

Results

Seventy-seven patients (81 implants) completed the 5-year follow-up. The 5-year cumulative survival and success rates were 97.8%, and the mean MBL change from implant insertion to 5 years was − 0.80 ± 1.13 mm. Optimal papilla index scores were observed at 90.1% of sites at 5 years compared with 32.8% of sites at insertion. Pink esthetic score, modified bleeding and plaque indices, and OHIP showed statistically significant improvement at the 5-year follow-up.

Conclusions

Immediately provisionalized tapered conical connection implants promote marginal bone stability and excellent esthetic outcomes after 5 years of function.

Clinical relevance

This treatment is a viable option for patients requiring immediately provisionalized single-tooth restorations in the esthetic zone and shows favorable long-term clinical outcomes, including marginal bone stability and excellent esthetics.

Zirconia vs. Titanium Dental Implants: Primary Stability In-Vitro Analysis

The present experimental trial uses two types of dental implants, one made of titanium (Ti₆A_l4V) and the other one of zirconia (ZrO₂), but both of identical design, to compare their stability and micro-movements values under load. One of each type of implant (n = 42) was placed into 21 cow ribs, recording the insertion torque and the resonance frequency using a specific transducer. Subsequently, a prosthetic crown made of PMMA was screwed onto each of the implants in the sample. They were then subjected to a static compression load on the vestibular cusp of the crown. The resulting micromovements were measured. The zirconia implants obtained a higher mean of both IT and RFA when compared with those of titanium, with statistically significant differences in both cases (p = 0.0483 and p = 0.0296). However, the micromovement values when load was applied were very similar for both types, with the differences between them (p = 0.3867) not found to be statistically significant. The results show that zirconia implants have higher implant stability values than titanium implants. However, the fact that there are no differences in micromobility values implies that caution should be exercised when applying clinical protocols for zirconia based on RFA, which only has evidence for titanium.

Modification of the surface nanotopography of implant devices: A translational perspective

There is an increasing need for the development of superior, safe, and more sophisticated implants, especially as our society historically has been moving towards an increasingly aging population. Currently, most research is being focused on the next generation of advanced medical implants, that are not only biocompatible but have modified surfaces that direct specific immunomodulation at cellular level. While there is a plethora of information on cell-surface interaction and how surfaces can be nanofabricated at research level, less is known about how the academic knowledge has been translated into clinical trials and commercial technologies. In this review, we provide a clinical translational perspective on the use of controlled physical surface modification of medical implants, presenting an analysis of data acquired from clinical trials and commercial products. We also evaluate the state-of-the-art of nanofabrication techniques that are being applied for implant surface modification at a clinical level. Finally, we identify some current challenges in the field, including the need of more advanced nanopatterning techniques, the comparatively small number of clinical trials and comment on future avenues to be explored for a successful clinical translation.

Effect of macrogeometry and bone type on insertion torque, primary stability, surface topography damage and titanium release of dental implants during surgical insertion into artificial bone

This study investigated the influence of implant macrogeometry and bone type on insertion torque (IT), primary stability (ISQ), surface topography damage, and the amount of titanium (Ti) released during insertion. Forty implants with different macrogeometries (Facility - Cylindrical with spiral-shaped threads; Alvim - Tapered with buttress-shaped threads) were inserted into artificial bone types I-II and III-IV. Surface morphology was evaluated by Scanning Electron Microscope (SEM) and roughness parameters with Laser Scanning Confocal Microscopy (LSCM) before and after insertion (AI). Implant macrogeometry was characterized by LSCM. The chemical composition of bone beds was determined by SEM associated with Energy Dispersive X-Ray Spectroscopy. The amount of Ti released was analyzed with Energy Dispersive X-Ray Fluorescence. Alvim had greater IT and ISQ than Facility. Bone types I-II require higher IT of implants. Alvim also had greater internal threads angle, higher initial roughness, and significant reduction of roughness AI, compared to Facility. The functional surface height reduced AI, especially in flank and valley of threads. Height of surface roughness of Alvim and Facility implants was similar AI. Implants surface morphology changes and metallic particles on bone beds were observed after implant insertion, mainly into bone types III-IV. Implants inserted into bone types I-II showed less surface damage. Alvim implants released more Ti (37.52 ± 25.03 ppm) than Facility (11.66 ± 28.55 ppm) on bone types III-IV. The implant macrogeometry and bone types affect IT, ISQ, surface damage, and Ti amount released during insertion. Alvim implants were more wear susceptible, releasing higher Ti concentration during insertion into bone types III-IV.

Impact of a Hydrophilic Dental Implant Surface on Osseointegration: Biomechanical Results in Rabbit

This study aimed to evaluate the effect of surface hydrophilicity on the biomechanical aspects of osseointegration of dental implants in the tibia and femur of rabbits. Forty-eight mature female New Zealand White rabbits were included, and 96 commercially pure, Grade 4, titanium dental implants (control group), and 96 implants of same macro geometry with the hydrophilic surface (test group) were used in this study. One osteotomy was performed in each tibia and femur on both sides of the rabbit, and four implants were placed in each rabbit. Control and test groups were randomly allocated on the left and right sides. During surgery, insertion torque (ITQ) value of the complete implant placement was recorded. After healing periods of 0, 2, 4, and 8 weeks after surgery, implant stability quotient (ISQ) value, and removal torque (RTQ) values were measured. No statistical difference was observed for ITQ, for ISQ and for RTQ between the control group and test group in tibia/femur for all time periods. The effect of hydrophilic properties on moderately roughened surfaces has no impact in terms of biomechanical outcomes (ISQ values and RTQ values) after a healing period of 2 to 8 weeks in rabbit tibias /femurs.

Biofilm and cell adhesion strength on dental implant surfaces via the laser spallation technique

OBJECTIVE

The aims of this study are to quantify the adhesion strength differential between an oral bacterial biofilm and an osteoblast-like cell monolayer to a dental implant-simulant surface and develop a metric that quantifies the biocompatible effect of implant surfaces on bacterial and cell adhesion.

METHODS

High-amplitude short-duration stress waves generated by laser pulse absorption are used to spall bacteria and cells from titanium substrates. By carefully controlling laser fluence and calibration of laser fluence with applied stress, the adhesion difference between Streptococcus mutans biofilms and MG 63 osteoblast-like cell monolayers on smooth and rough titanium substrates is obtained. The ratio of cell adhesion strength to biofilm adhesion strength (i.e., Adhesion Index) is determined as a nondimensionalized parameter for biocompatibility assessment.

RESULTS

Adhesion strength of 143 MPa, with a 95% C.I. (114, 176), is measured for MG 63 cells on smooth titanium and 292 MPa, with a 95% C.I. (267, 306), on roughened titanium. Adhesion strength for S. mutans on smooth titanium is 320 MPa, with a 95% C.I. (304, 333), and remained relatively constant at 332 MPa, with a 95% C.I. (324, 343), on roughened titanium. The calculated Adhesion Index for smooth titanium is 0.451, with a 95% C.I. (0.267, 0.622), which increased to 0.876, with a 95% C.I. (0.780, 0.932), on roughened titanium.

SIGNIFICANCE

The laser spallation technique provides a platform to examine the tradeoffs of adhesion modulators on both biofilm and cell adhesion. This tradeoff is characterized by the Adhesion Index, which is proposed to aid biocompatibility screening and could help improve implantation outcomes. The Adhesion Index is implemented to determine surface factors that promote favorable adhesion of cells greater than biofilms. Here, an Adhesion Index ≫ 1 suggests favorable biocompatibility.

Socket Preservation Using Xenograft Does Not Impair Implant Primary Stability in Sheep: Clinical, Histological, and Histomorphometric Study

Implant primary stability, which depends mainly on the amount and quality of bone, is important for implant survival. Socket preservation aims to reduce bone volumetric changes after tooth extraction. This animal study aims to examine whether preserving a ridge by using xenograft impairs the primary stability of the implant. Eighteen artificial bone defects were prepared in 4 sheep (5- and 8-mm length). Defects were randomly grafted with xenografts: Bio-Oss (BO), Bio-Active bone (BB), or left for natural healing (control). After 8 weeks, bone biopsy was harvested and dental implants installed. During installation, peak insertion torque (IT) was measured by hand ratchet, and primary stability by the Osstell method. Histomorphometric analysis showed a higher percentage of new bone formation in the naturally healed defects compared to sites with xenograft (control: 68.66 ± 4.5%, BB: 48.75 ± 4.34%, BO: 50.33 ± 4.0%). Connective tissue portion was higher in the BO and BB groups compared to control (44.25 ± 2.98%, 41 ± 6%, and 31.33 ± 4.5%, P < .05, respectively). Residual grafting material was similar in BO and BB (7 ± 2.44%, 8.66 ± 2.1%, respectively). Mean IT and implant stability quotient (ISQ) values were not statistically different among the groups. A positive correlation was found between IT and ISQ (r = 0.65, P = 0). In conclusion, previously grafted defects with xenograft did not influence primary stability and implant insertion torque in delayed implant placement. These results may be attributed to a relatively high bone fill of the defect (∼50%) 2 months after grafting.

Effects of surface sub-micrometer topography following oxalic acid treatment on bone quantity and quality around dental implants in rabbit tibiae

Background

To explore the effects of topographical modification of titanium substrates at submicron level by oxalic acid treatment on bone quality and quantity around dental implants in rabbit tibiae.

Methods

A total of 60 blasted CP-grade IV titanium dental implants were used. Twenty-eight control implant surfaces were treated with a mixture of HCl/H₂SO₄, whereas 28 other test implant surfaces were treated with oxalic acid following HCl/H₂SO₄ treatment. Two randomly selected sets of control or test implants were placed in randomly selected proximal tibiae of 14 female Japanese white rabbits. Euthanasia was performed 4 and 8 weeks post-implant placement. Bone to implant contact (BIC), bone area fraction (BAF), ratios of mature and immature bone to total bone, and the amount and types of collagen fibers were evaluated quantitatively. Two control and two test implants were used to analyze surface characteristics.

Results

Treatment by oxalic acid significantly decreased Sa and increased Ra of test implant surfaces. BIC in test implants was increased without alteration of BAF and collagen contents at 4 and 8 weeks after implant placement when compared with control implants. The ratios of immature and mature bone to total bone differed significantly between groups at 4 weeks post-implantation. Treatment by oxalic acid increased type I collagen and decreased type III collagen in bone matrices around test implants when compared with control implants at 8 weeks after implant placement. The effects of topographical changes of implant surfaces induced by oxalic acid on BAF, mature bone, collagen contents, and type I collagen were significantly promoted with decreased immature bone formation and type III collagen in the later 4 weeks post-implantation.

Conclusions

Treatment of implant surfaces with oxalic acid rapidly increases osseointegration from the early stages after implantation. Moreover, submicron topographical changes of dental implants induced by oxalic acid improve bone quality based on bone maturation and increased production of type I collagen surrounding dental implants in the late stage after implant placement.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40729-020-00275-x.

Does implant surface hydrophilicity influence the maintenance of surface integrity after insertion into low-density artificial bone?

OBJECTIVE

To evaluate the influence of hydrophilicity on the surface integrity of implants after insertion in low-density artificial bone and to determine the distribution of titanium (Ti) particles along the bone bed.

METHODS

Forty-eight dental implants with different designs (Titamax Ex, Facility, Alvim, and Drive) and surface treatments (Neoporos® and Aqua™) were inserted into artificial bone blocks with density compatible with bone type III-IV. Hydrophobic Neoporos® surfaces were obtained by sandblasting and acid etching while hydrophilic Aqua™ surfaces were obtained by sandblasting, acid etching, and storage in an isotonic 0.9% NaCl solution. The surface integrity was evaluated by Scanning Electron Microscope (SEM) and the surface roughness parameters (Sa, Sp, Ssk, Sdr, Spk, Sk, and Svk) and surface area were measured with Laser Scanning Confocal Microscopy before and after installation. Bone beds were inspected with Digital Microscopy and micro X-Ray Fluorescence (μ-XRF) to analyze the metallic element distribution along the bone bed.

RESULTS

Acqua™ implants had higher initial Sa and a pronounced reduction of Sa and Sp during insertion, compared to NeoPoros® implants. After insertion, Sa and Sp of Acqua™ and NeoPoros® implants equalized, differing only between designs of Acqua™ implants. Surface damage was observed after insertion, mainly in the apical region. Facility implants that are made of TiG5 released fewer debris particles, while the highest Ti intensity was detected in the cervical region of the Titamax Ex Acqua™ and Drive Acqua™ implants.

SIGNIFICANCE

Physicochemical modifications to achieve surface hydrophilicity created a rougher surface that was more susceptible to surface alterations, resulting in more Ti particle release into the bone bed during surgical insertion. The higher Ti intensities detected in the cervical region of bone beds may be related to peri-implantitis and marginal bone resorption.

Comparison of nonself-tapping tapered implant and self-tapping hybrid implant in terms of implant stability at initial and second fixation: A prospective randomized clinical trial

BACKGROUND

Various features are provided in dental implants to improve initial fixation.

PURPOSE

To compare the implant stability of the nonself-tapping tapered implant and self-tapping hybrid implant over a 3-month healing period.

MATERIALS AND METHODS

A randomized controlled trial was conducted. Patients were randomly divided into tapered and self-tapping groups. Patients in the tapered group received NobelReplace Tapered (Nobel Biocare, Sweden) implants, while those in the self-tapping group received NobelSpeedy (Nobel Biocare, Sweden) implants. Implant stability was measured by resonance frequency analysis at surgery and 3 months following implant insertion. Data were analyzed using an independent t-test.

RESULTS

Forty-three patients (tapered group: 21, self-tapping group: 22) received a total of 88 implants. Initial stability in the tapered group was significantly higher (mean: 60.14, SD: 12.40) than that in the self-tapping group (mean: 54.72, SD: 7.92). Implant stability significantly increased 3 months after implantation in the tapered group (mean: 66.61, SD: 9.00) and self-tapping group (mean: 64.01, SD: 5.78). No significant intergroup difference in implant stability was noted 3 months after surgery.

CONCLUSIONS

The tapered shape affected initial fixation more than the self-tapping function. However, during the second fixation, both implants showed good stability, and the difference disappeared.

Osseointegration of a novel injection molded 2-piece ceramic dental implant: a study in minipigs

OBJECTIVES

This study compared the osseointegrative potential of a novel injection molded zirconia dental implant (Neodent Zi ceramic implant, test) and a commercially available titanium implant (Neodent Alvim implant, control) in terms of histomorphometrically derived bone-to-implant contact (BIC), first bone-to-implant contact (fBIC), and the ratio of bone area to total area (BATA) around the implant.

MATERIALS AND METHODS

A total of 36 implants, 18 per individual test device, were implanted in a split-mouth arrangement in either side of the edentulous and fully healed mandible of 6 minipigs. Histomorphometric analysis of BIC, fBIC, and BATA were performed 8 weeks post implantation and subjected to statistical non-inferiority testing. Surface characteristics of both implant types were compared in terms of contact angle, surface topography, and elemental composition.

RESULTS

BIC, fBIC, and coronal BATA values of test and control implants were statistically comparable and non-inferior. BIC values of 77.8 ± 6.9% vs. 80.7 ± 6.9% (p = 0.095) were measured for the test and control groups. fBIC lingual values were - 238 ± 328 μm compared with - 414 ± 511 μm (p = 0.121) while buccal values were - 429 ± 648 μm and - 588 ± 550 μm (p = 0.230) for the test and control devices, respectively. BATA in the apical segment was significantly higher in the test group compared with the control group (67.2 ± 11.8% vs. 59.1 ± 11.4%) (p = 0.0103). Surface topographies of both implant types were comparable. Surface chemical analysis indicated the presence of carbonaceous adsorbates which correlated with a comparable and predominantly hydrophobic character of the implants.

CONCLUSION

The results demonstrate that the investigated zirconia implants, when compared with a commercially available titanium implant, show equivalent and non-inferior bone integration, bone formation, and alveolar bone level maintenance. This qualifies the investigated zirconia implant as a potential candidate for clinical development.

CLINICAL RELEVANCE

This study investigated the osseointegration of a novel zirconia 2-piece dental implant prototype intended for clinical development. With the aim of translating this prototype into clinical development preclinical models, procedures and materials within this study have been selected as close to clinical practice and human physiological conditions as possible.

Early Loading of Mandibular Molar Single Implants: 1 Year Results of a Randomized Controlled Clinical Trial

The purpose of this study was to compare the implant survival, peri-implant marginal bone level, and peri-implant soft tissue of three different types of implants. This was performed with an early loading protocol, using a complete digital workflow, for one year of follow-up. Twenty-four patients with a single missing tooth in the mandibular posterior region were randomly assigned to the control group (SLActive Bone level implant; Institut Straumann AG, Basel, Switzerland), experiment group 1 (CMI IS-III Active implant; Neobiotech Co., Seoul, Korea), and experiment group 2 (CMI IS-III HActive implant; Neobiotech Co., Seoul, Korea). For each patient, a single implant was installed using the surgical template, and all prostheses were fabricated using a computer-aided design/computer-aided manufacturing system on a 3-dimensional model. A provisional prosthesis was implanted at 4 weeks, and a definitive monolithic zirconia prosthesis was substituted 12 weeks following the implant placement. The implant stability quotient (ISQ) and peri-implant soft tissue parameters were measured, and periapical radiographs were taken at 1, 3, 4, 8, 12, 24, 36, and 48 weeks after implant placements. Seven implants in the control group, nine implants in the experiment 1 group, and eight implants in the experiment 2 group were analyzed. There were no significant differences among the three groups in terms of insertion torque, ISQ values between surgery and 8 weeks of follow-up, marginal bone loss at 48 weeks of follow-up, and peri-implant soft tissue parameters (P > 0.05). Statistically significant differences in ISQ values were observed between the control and experiment 1 groups, and the control and experiment 2 groups at the 12 to 48 weeks' follow-ups. Within the limits of this prospective study, an early loading protocol can be applied as a predictable treatment modality in posterior mandibular single missing restorations, achieving proper primary stability.

Effect of macro-design in the primary stability of short and extra-short implants using resonance frequency analysis. An ex vivo study

Objective

This study aimed to determine the effect of macro design in the primary stability of short and extra-short implants using resonance frequency analysis (RFA).

Material and methods

On an ex-vivo model using pig's ribs, we inserted 80 short and extra-short dental implants (20 implants per brand): Biohorizons®(B) 4.6 × 6mm; Intralock®(I) 4.75 × 6.5 mm; Straumann®(S) 4.1 × 4mm; and Tixos®(T) 5 × 5mm. Primary implant stability was measured using an RFA device. We compared mean ISQ values through ANOVA test.

Results

Mean ISQ values: B = 73.36 (±3.39); I = 75.13 (±3.88); S = 65.38 (±8.38); T = 72.13 (±11). B and I showed higher ISQ than S (p-value < 0.001). Short (I) showed higher ISQ than extra-short (B,S,T) implants (p-value = 0.001). Tapered (B,I) had higher ISQ than parallel (S,T) implants (p-value < 0.001). There was a moderate positive correlation between ISQ and length (r = 0.52), and a weak correlation with diameter (r = 0.33).

Discussion

The final result is a combination of implant design, length, and diameter. Tapered design (B and I) and larger implants (I) showed better primary stability in terms of ISQ values. This information could be beneficial at implant selection in a severely reabsorbed low-quality bone, privileging length (as long as it is safe), and conical walls design.

Evaluation of the implant stability and the marginal bone level changes during the first three months of dental implant healing process: A prospective clinical study

Achievement of adequate implant stability is one of the determinants for long-term successful osseointegration. Resonance frequency analysis was developed to monitor implant stability and is now a well-recognized, non-invasive tool for determining the appropriate time for functional loading. However, there have been few studies with continuous evaluation and comparison of implant stability and marginal bone level changes between two different macro designs and clinical situations during the implant healing process. Thus, the purpose of this clinical trial is to evaluate the implant stability and marginal bone level changes of straight and conical implants during the implant healing process. In this prospective clinical trial, 25 participants were randomized to either straight or conical implants. A total of 32 titanium dental implants with a length of 9 mm or 11 mm were installed in the maxilla and the mandible according to the manufacturer's instructions. A resonance frequency analyzer was used to measure the implant stability quotient (ISQ) at the time of implant placement and after 2 weeks, 4 weeks, 6 weeks, 8 weeks, 10 weeks, and 12 weeks of healing. The changes in the peri-implant marginal bone level were evaluated from digital radiographic films taken at the time of implant placement and after 4 weeks, 8 weeks, and 12 weeks of healing. The preliminary results of this study revealed higher ISQ values and better healing tendency for conical implants in comparison with straight implants in the maxilla. Similar ISQ values and healing tendency were observed for straight and conical implants in the mandible. No significant differences in marginal bone loss were found between the straight and conical implants. However, in the mandible, slightly more marginal bone loss was found with the conical implants than straight implants after 12 weeks of healing. In conclusion, ISQ healing tendency and marginal bone loss are influenced by implant macro-design and jaw regions. Straight implants revealed similar ISQ healing tendency and marginal bone loss in both the mandible and maxilla. Conical implants were confirmed more beneficial for maintenance of implant stability and marginal bone level in the maxilla.

De Aza P. Can changes in implant macrogeometry accelerate the osseointegration process?: An in vivo experimental biomechanical and histological evaluations

OBJECTIVES

The propose was to compare this new implant macrogeometry with a control implant with a conventional macrogeometry.

MATERIALS AND METHODS

Eighty-six conical implants were divided in two groups (n = 43 per group): group control (group CON) that were used conical implants with a conventional macrogeometry and, group test (group TEST) that were used implants with the new macrogeometry. The new implant macrogeometry show several circular healing cambers between the threads, distributed in the implant body. Three implants of each group were used to scanning electronic microscopy (SEM) analysis and, other eighty samples (n = 40 per group) were inserted the tibia of ten rabbit (n = 2 per tibia), determined by randomization. The animals were sacrificed (n = 5 per time) at 3-weeks (Time 1) and at 4-weeks after the implantations (Time 2). The biomechanical evaluation proposed was the measurement of the implant stability quotient (ISQ) and the removal torque values (RTv). The microscopical analysis was a histomorphometric measurement of the bone to implant contact (%BIC) and the SEM evaluation of the bone adhered on the removed implants.

RESULTS

The results showed that the implants of the group TEST produced a significant enhancement in the osseointegration in comparison with the group CON. The ISQ and RTv tests showed superior values for the group TEST in the both measured times (3- and 4-weeks), with significant differences (p < 0.05). More residual bone in quantity and quality was observed in the samples of the group TEST on the surface of the removed implants. Moreover, the %BIC demonstrated an important increasing for the group TEST in both times, with statistical differences (in Time 1 p = 0.0103 and in Time 2 p < 0.0003).

CONCLUSIONS

Then, we can conclude that the alterations in the implant macrogeometry promote several benefits on the osseointegration process.

Relevant Design Aspects to Improve the Stability of Titanium Dental Implants

Post-extractional implants and immediate loading protocols are becoming much more frequent in everyday clinical practice. Given the existing literature about tapered implants, the objective of this paper was to understand whether implant shape had a direct influence on the results of the insertion torque (IT) and implant stability quotient (ISQ). Seven tapered implant prototypes were developed and distributed into three groups and compared with a control cylindrical implant-VEGA by Klockner Implant System. The implants were inserted into bovine bone type III according to Lekholm and Zarb Classification. The sample size was n = 30 for the three groups. Final IT was measured with a torquemeter, and the ISQ was measured with Penguin Resonance Frequency Analysis (RFA). Modifications done to the Prototype I did not reveal higher values of the ISQ and IT when compared to VEGA. In the second group, when comparing the five prototypes (II-VI) with VEGA, it was seen that the values of the ISQ and IT were not always higher, but there were two values of the ISQ that were statistically significantly higher with the 4.0 mm diameter Prototypes II (76.3 ± 6.1) and IV (78 ± 3.7). Prototype VII was the one with higher and significant values of the ISQ and IT. In both diameters and in both variables, all differences were statistically significant enough to achieve the higher values of primary stability values (IT and ISQ). Given the limitations of this study, it can be concluded that when there is an increase of the diameter of the implant and body taper, there is an increase of the ISQ and IT, showing that the diameter of the implant is an important criteria to obtain higher values of primary stability.

Modified surgical drilling protocols influence osseointegration performance and predict value of implant stability parameters during implant healing process

OBJECTIVE

The aim of this study was to evaluate the effects of three different surgical drilling protocols on changes of implant stability parameters and osseointegration performance during the healing period in rabbit femoral condyles.

MATERIAL AND METHODS

Thirty New Zealand white rabbits were used in this study. Three experimental groups according to different surgical drilling protocols (undersized, standard and oversized preparation) were designed. Measurements of implant stability parameters were performed immediately after implant insertion and then at 1, 2, 4, and 8 weeks after the operation. After the animals were sacrificed, the bone blocks with implant were prepared for histological evaluation and histomorphometric analysis.

RESULTS

The results demonstrated that the ISQ values of each group increased gradually through the whole healing period, while the damping factor showed the opposite tendency. The histomorphometric analysis revealed that BIC (bone-implant contact) values gradually increased with time until 8 weeks of healing at each group. In addition, the undersized group has the highest initial BIC (25.16% ± 7.25%) and the lowest values were found in oversized group (9.13% ± 5.89%). Moreover, a higher correlation (R² = 0. 9817) between ISQ and BIC values in oversized group and moderate correlations between DF and BIC values in undersized group (R² = 0.823) were demonstrated.

CONCLUSIONS

The undersized drilling protocol group presented the highest implant stability and BIC values in the whole healing period, while the similar tendency of results was found between standard and oversized drilling protocol groups.

CLINICAL RELEVANCE

These results suggested that undersized drilling protocol is mechanically and biologically beneficial in low-density bone. The modifications of surgical drilling protocols would influence the predictive value of implant stability parameters for osseointegration performance.

Primary Stability of Short Implants Inserted Using Piezoelectric or Drilling Systems: An In Vitro Comparison

The primary objective of the present in vitro study was to evaluate the influence of implant site preparation technique (drills vs ultrasonic instrumentation) on the primary stability of short dental implants with two different designs inserted in simulated low-quality cancellous bone. Eighty implant sites were prepared in custom-made solid rigid polyurethane blocks with two different low cancellous bone densities (5 or 15 pounds per cubic foot [PCF]), equally distributed between piezoelectric (Surgysonic Moto, Esacrom, Italy) and conventional drilling techniques. Two short implant systems (Prama and Syra, Sweden & Martina) were tested by inserting 40 fixtures of each system (both 6.0 mm length and 5.0 mm diameter), divided in the four subgroups (drills/5 PCF density; drills/15 PCF density; piezo/5 PCF density; piezo/15 PCF density). Insertion torque (Ncm), implant stability quotient values, removal torque (Ncm), and surgical time were recorded. Data were analyzed by 3-way ANOVA and Scheffé's test (α = 0.05). With slight variations among the considered dependent variables, overall high primary implant stability was observed across all subgroups. Piezoelectric instrumentation allowed for comparable or slightly superior primary stability in comparison with the drilling procedures in both implant systems. The Prama implants group showed the highest mean reverse torque and Syra implants the highest implant stability quotient values. Piezoelectric implant site preparation took prolonged operative time compared to conventional preparation with drills; among the drilling procedures, Syra system required fewer surgical steps and shorter operative time.

Short implants (≤6 mm) versus longer implants with sinus floor elevation in atrophic posterior maxilla: a systematic review and meta-analysis

OBJECTIVES

To compare the use of short implants (≤6 mm) in atrophic posterior maxilla versus longer implants (≥10 mm) with sinus floor elevation.

DESIGN

A systematic review and meta-analysis based on randomised controlled trials (RCTs).

DATA SOURCES

Electronic searches were conducted in PubMed, Embase and the Cochrane CENTRAL. Retrospective and prospective hand searches were also performed.

ELIGIBILITY CRITERIA

RCTs comparing short implants (≤6 mm) and longer implants (≥10 mm) with sinus floor elevation were included. Outcome measures included implant survival (primary outcome), marginal bone loss (MBL), complications and patient satisfaction.

DATA EXTRACTION AND SYNTHESIS

Risks of bias in and across studies were evaluated. Meta-analysis, subgroup analysis and sensitivity analysis were undertaken. Quality of evidence was assessed according to Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

A total of seven RCTs involving 310 participants were included. No significant difference in survival rate was found for 1-3 years follow-up (RR 1.01, 95% CI 0.97 to 1.04, p=0.74, I²=0%, moderate-quality evidence) or for 3 years or longer follow-up (RR 1.00, 95% CI 0.97 to 1.04, p=0.79, I²=0%, moderate-quality evidence). However, short implants (≤6 mm) showed significantly less MBL in 1-3 years follow-up (MD=-0.13 mm, 95% CI -0.21 to 0.05; p=0.001, I²=87%, low-quality evidence) and in 3 years or longer follow-up (MD=-0.25 mm, 95% CI -0.40 to 0.10; p=0.001, I²=0%, moderate-quality evidence). In addition, short implant (≤6 mm) resulted in fewer postsurgery reaction (RR 0.11, 95% CI 0.14 to 0.31, p<0.001, I²=40%, moderate-quality evidence) and sinus perforation or infection (RR 0.11, 95% CI 0.02 to 0.63, p=0.01, I²=0%, moderate-quality evidence).

CONCLUSIONS

For atrophic posterior maxilla, short implants (≤6 mm) are a promising alternative to sinus floor elevation, with comparable survival rate, less MBL and postsurgery reactions. Additional high-quality studies are needed to evaluate the long-term effectiveness of short implants (≤6 mm).

TRIAL REGISTERATION NUMBER

The protocol has been registered at PROSPERO (CRD42018103531).

Biomechanical Effects of a New Macrogeometry Design of Dental Implants: An In Vitro Experimental Analysis

The purpose of the present study was to measure and compare the insertion torque, removal torque, and the implant stability quotient by resonance frequency analysis in different polyurethane block densities of two implant macrogeometries. Four different polyurethane synthetic bone blocks were used with three cortical thickness: Bone 1 with a cortical thickness of 1 mm, Bone 2 with a cortical thickness of 2 mm, Bone 3 with a cortical thickness of 3 mm, and Bone 4, which was totally cortical. Four groups were created in accordance with the implant macrogeometry (n = 10 per group) and surface treatment: G1—regular implant design without surface treatment; G2—regular implant design with surface treatment; G3—new implant design without surface treatment; G4—new implant design with surface treatment. All implants used were 4 mm in diameter and 10 mm in length and manufactured in commercially pure titanium (grade IV) by Implacil De Bortoli (São Paulo, Brazil). The implants were installed using a computed torque machine, and following installation of the implant, the stability quotient (implant stability quotient, ISQ) values were measured in two directions using Osstell devices. The data were analyzed by considering the 5% level of significance. All implant groups showed similar mean ISQ values without statistical differences (p > 0.05), for the same synthetic bone block: for Bone 1, the value was 57.7 ± 3.0; for Bone 2, it was 58.6 ± 2.2; for Bone 3, it was 60.6 ± 2.3; and for Bone 4, it was 68.5 ± 2.8. However, the insertion torque showed similar higher values for the regular macrogeometry (G1 and G2 groups) in comparison with the new implant macrogeometry (G3 and G4 groups). The analysis of the results found that primary stability does not simply depend on the insertion torque but also on the bone quality. In comparison with the regular implant macrogeometry, the new implant macrogeometry decreased the insertion torque without affecting the implant stability quotient values.

Intraosseous Temperature Change during Installation of Dental Implants with Two Different Surfaces and Different Drilling Protocols: An In Vivo Study in Sheep

Background: The intraosseous temperature during implant installation has never been evaluated in an in vivo controlled setup. The aims were to investigate the influence of a drilling protocol and implant surface on the intraosseous temperature during implant installation, to evaluate the influence of temperature increase on osseointegration and to calculate the heat distribution in cortical bone. Methods: Forty Brånemark implants were installed into the metatarsal bone of Finnish Dorset crossbred sheep according to two different drilling protocols (undersized/non-undersized) and two surfaces (moderately rough/turned). The intraosseous temperature was recorded, and Finite Element Model (FEM) was generated to understand the thermal behavior. Non-decalcified histology was carried out after five weeks of healing. The following osseointegration parameters were calculated: Bone-to-implant contact (BIC), Bone Area Fraction Occupancy (BAFO), and Bone Area Fraction Occupancy up to 1.5 mm (BA1.5). A multiple regression model was used to identify the influencing variables on the histomorphometric parameters. Results: The temperature was affected by the drilling protocol, while no influence was demonstrated by the implant surface. BIC was positively influenced by the undersized drilling protocol and rough surface, BAFO was negatively influenced by the temperature rise, and BA1.5 was negatively influenced by the undersized drilling protocol. FEM showed that the temperature at the implant interface might exceed the limit for bone necrosis. Conclusion: The intraosseous temperature is greatly increased by an undersized drilling protocol but not from the implant surface. The temperature increase negatively affects the bone healing in the proximity of the implant. The undersized drilling protocol for Brånemark implant systems increases the amount of bone at the interface, but it negatively impacts the bone far from the implant.

New Implant Macrogeometry to Improve and Accelerate the Osseointegration: An In Vivo Experimental Study

A new implant design with healing chambers in the threads was analyzed and compared with a conventional implant macrogeometry, both implants models with and without surface treatment. Eighty conical implants were prepared using commercially pure titanium (grade IV) by the company Implacil De Bortoli (São Paulo, Brazil). Four groups were performed, as described below: Group 1 (G1), traditional conical implants with surface treatment; group 2 (G2), traditional conical implants without surface treatment (machined surface); group 3 (G3), new conical implant design with surface treatment; group 4 (G4), new conical implant design without surface treatment. The implants were placed in the two tibias (n = 2 implants per tibia) of twenty New Zealand rabbits determined by randomization. The animals were euthanized after 15 days (Time 1) and 30 days (Time 2). The parameters evaluated were the implant stability quotient (ISQ), removal torque values (RTv), and histomorphometric evaluation to determine the bone to implant contact (%BIC) and bone area fraction occupancy (BAFO%). The results showed that the implants with the macrogeometry modified with healing chambers in the threads produced a significant enhancement in the osseointegration, accelerating this process. The statistical analyses of ISQ and RTv showed a significative statistical difference between the groups in both time periods of evaluation (p ≤ 0.0001). Moreover, an important increase in the histological parameters were found for groups G3 and G4, with significant statistical differences to the BIC% (in the Time 1 p = 0.0406 and in the Time 2 p < 0.0001) and the BAFO% ((in the Time 1 p = 0.0002 and in the Time 2 p = 0.0045). In conclusion, the result data showed that the implants with the new macrogeometry, presenting the healing chambers in the threads, produced a significant enhancement in the osseointegration, accelerating the process.

Correlation between Implant Geometry, Bone Density, and the Insertion Torque/Depth Integral: A Study on Bovine Ribs

During insertion of dental implants, measurement of dynamic parameters such as the torque-depth curve integral or insertion energy might convey more information about primary stability than traditional static parameters such as the insertion or removal torque. However, the relationship between these dynamic parameters, bone density, and implant geometry is not well understood. The aim of this investigation was to compare static and dynamic implant stability measurements concerning three different implant designs when implants were inserted into bovine bone ribs and dynamic parameters were collected using an instantaneous torque measuring implant motor. Standard implant osteotomies were created in segments of bovine ribs. After measuring the bone density using the implant motor, 10 cylindrical, 10 hybrid tapered-cylindrical, and 10 modified cylindrical implants were placed, and their primary stability was assessed by measuring the torque–depth curve integral, along with insertion and removal torque. The relationship between these quantities, bone density, and implant geometry was investigated by means of regression and covariance analysis. The regression lines describing the relationship between the torque–depth integral and bone density differed significantly from those describing the relationship between insertion torque, removal torque, and bone density for all three designs. The torque–depth curve integral provides different information about immediate primary stability than insertion and removal torque and in certain clinical conditions might be more reliable than these static parameters for assessing implant primary stability. Further research should be carried out to investigate the findings of the present study.

Comparative study of stress characteristics in surrounding bone during insertion of dental implants of three different thread designs: A three-dimensional dynamic finite element study

The objective of this study is to evaluate the stress distribution characteristics around three different dental implant designs during insertion into bone, using dynamic finite element stress analysis. Dental implant placement was simulated using finite element models. Three implants with different thread and body designs (Model 1: root form implant with three different thread shapes; Model 2: tapered implant with a double-lead thread; and Model 3: conical tapered implant with a constant buttress thread) were assigned to insert into prepared bone cavity models until completely placed. Stress and strain distributions were descriptively analyzed. The von Mises stresses within the surrounding bone were measured. At the first 4-mm depth of implant insertion, maximum stress within cortical bone for Model 3 (175 MPa) was less than the other models (180 MPa each). Stress values and concentration area were increasing whereas insertion depth increased. At full implant insertion depth, maximum stress level in Model 1 (35 MPa) within the cancellous bone was slightly greater than in Models 2 (30 MPa) and 3 (25 MPa), respectively. Generally, for all simulations, the highest stress value and the location of the stress concentration area were mostly in cortical bone. However, the stress distribution patterns during the insertion process were different between the models depending on the different designs geometry that contacted the surrounding bone. Different implant designs affect different stress generation patterns during implant insertion. A range of stress magnitude, generated in the surrounding bone, may influence bone healing around dental implants and final implant stability.

[Factors affecting osteointegration and the use of early functional load to reduce the duration of treatment in dental implantation]

The article presents literature data on the impact of the surface and shape of dental implants and early functional load with aesthetic and functional rehabilitation on osteointegration and stability of implants at various implantation terms.

"Peroperative estimation of bone quality and primary dental implant stability"

OBJECTIVES

Dental implants are widely used to restore function and appearance. It may be essential to choose the appropriate drilling protocol and implant design in order to optimise primary stability. This could be achieved based on an assessment of the implantation site with respect to bone quality and objective biomechanical descriptors such as stiffness and strength of the bone-implant system. The aim of this ex vivo study is to relate these descriptors with bone quality, with a pre-implantation indicator of implant stability: pilot-hole drilling force (F_drilling), and with two post-implantation indicators: maximal implantation torque (T_implantation) and resonance frequency analysis (RFA).

METHODS

Eighty trabecular bone specimens were cored from human vertebrae and bovine tibiae. Bone volume fraction (BV/TV), a representative for bone quality, was obtained through micro-computed tomography scans. Implants were kept in controlled laboratory conditions following standard surgical procedures. Forces and torques were recorded and RFA was assessed after implantation. Off-axis compression tests were conducted on the implants until failure. Implant stability was identified by stiffness and ultimate force (F_ultimate). The relationships between BV/TV, Stiffness, F_ultimate and F_drilling, T_implantation, RFA were established.

RESULTS

F_drilling correlated well with BV/TV of the implantation site (r² = 0.81), stiffness (r² = 0.75) and F_ultimate (r² = 0.80). T_implantation correlated better with stiffness (r² = 0.86) and F_ultimate (r² = 0.94) than RFA (r² = 0.77 and r² = 0.74, respectively).

CONCLUSION

Our results indicate that BV/TV and bone-implant stability can be directly estimated by the force needed for the pilot drilling that occurs during the site preparation before implantation. Moreover, implantation torque outperforms RFA for evaluating the mechanical competence of the bone-implant system.

Can implant surfaces affect implant stability during osseointegration? A randomized clinical trial

This randomized clinical trial evaluated the insertion torque (IT), primary, and secondary stability of dental implants with different surface treatments during the osseointegration period. Nineteen patients with bilateral partial edentulism in the posterior mandibular region were randomly allocated to two implant brand groups and received implants with different surface treatments in the opposite site of the arch: Osseotite and Nanotite or SLA and SLActive. During implant placement, the maximum IT was recorded using a surgical motor equipped with a graphical user interface. The implant stability quotient (ISQ) was assessed immediately after the IT, and was measured weekly via resonance frequency analysis during 3 months. The data were analyzed by a one-way ANOVA, the Bonferroni test, paired t tests and Pearson's correlation coefficient. The IT values were similar (p > 0.05) for all implant types ranging from 43.82 ± 6.50 to 46.84 ± 5.06. All implant types behaved similarly until the 28th day (p > 0.05). Between 35 and 56 days, Osseotite and SLActive showed lower ISQ values (p < 0.001) compared to Nanotite and SLA implants. After 56 days, only Osseotite maintained significantly lower ISQ values than the other implants (p < 0.05). After 91 days the ISQ values were significantly higher than the baseline for all four implant types (p < 0.001). The ISQ and IT values were significantly correlated at the baseline and at the final evaluation for Osseotite, Nanotite, and SLActive implants (p < 0.001). After 91 days, ISQ and IT values were only significantly correlated for the Osseotite implants (p < 0.05). All implants types exhibited acceptable primary and secondary stability.

A review of nanostructured surfaces and materials for dental implants: surface coating, patterning and functionalization for improved performance

The emerging field of nanostructured implants has enormous scope in the areas of medical science and dental implants. Surface nanofeatures provide significant potential solutions to medical problems by the introduction of better biomaterials, improved implant design, and surface engineering techniques such as coating, patterning, functionalization and molecular grafting at the nanoscale. This review is of an interdisciplinary nature, addressing the history and development of dental implants and the emerging area of nanotechnology in dental implants. After a brief introduction to nanotechnology in dental implants and the main classes of dental implants, an overview of different types of nanomaterials (i.e. metals, metal oxides, ceramics, polymers and hydrides) used in dental implant together with their unique properties, the influence of elemental compositions, and surface morphologies and possible applications are presented from a chemical point of view. In the core of this review, the dental implant materials, physical and chemical fabrication techniques and the role of nanotechnology in achieving ideal dental implants have been discussed. Finally, the critical parameters in dental implant design and available data on the current dental implant surfaces that use nanotopography in clinical dentistry have been discussed.

Effect of Growth Hormone Supplementation on Osseointegration: A Systematic Review and Meta-analyses

OBJECTIVES

The aim of this study was to assess whether growth hormone (GH) replacement therapy can enhance implant osseointegration.

MATERIALS AND METHODS

A systematic literature search was conducted from 1982 to March 2016. A structured search using the keywords "growth hormone," "implants," and "osseointegration" was performed to identify preclinical and clinical in vivo controlled studies and was followed by a 2-phase search strategy. Initially, 31 potentially relevant articles were identified. After removal of duplicates and screening by title and abstract, 10 potential studies were included. Studies were assessed for bias and data were synthesized using a random-effects meta-analysis model.

RESULTS

All studies were preclinical animal trials, and the follow-up period ranged from 2 to 16 weeks. Seventy percent of the included studies reported an increase in bone-to-implant contact in animals receiving GH compared with controls. Meta-analysis showed a significant mean difference for bone to implant between GH groups versus controls (no GH supplementation) of 10.60% (95% confidence interval: 3.79%-17.41%) favoring GH administration.

CONCLUSION

GH treatment seems to promote osseointegration around implants in preclinical studies; however, these findings must be assessed in highly controlled human clinical trials as a number of confounding factors may have influenced the outcomes of the included studies.

Correlation between Insertion Torque and Implant Stability Quotient in Tapered Implants with Knife-Edge Thread Design

Aim

To evaluate the correlation between insertion torque (IT) and implant stability quotient (ISQ) in tapered implants with knife-edge threads.

Methods

Seventy-five identical implants (Anyridge, Megagen) were inserted by using a surgical drilling unit with torque control and an integrated resonance frequency analysis module (Implantmed, W&H). IT (N/cm) and ISQ were recorded and implants were divided into three groups (n = 25) according to the IT: low (<30), medium (30 < IT < 50), and high torque (>50). ISQ difference among groups was assessed by Kruskal-Wallis test, followed by Bonferroni-corrected Mann–Whitney U-test for pairwise comparisons. The strength of the association between IT and ISQ was assessed by Spearman Rho correlation coefficient (α = 0.05).

Results

At the pairwise comparisons, a significant difference of ISQ values was demonstrated only between low torque and high torque groups. The strength of the association between IT and ISQ value was significant for both the entire sample and the medium torque group, while it was not significant in low and high torque groups.

Conclusions

For the investigated implant, ISQ and IT showed a positive correlation up to values around 50 N/cm: higher torques subject the bone-implant system to unnecessary biological and mechanical stress without additional benefits in terms of implant stability. This trial is registered with NCT03222219.

Stability of tapered and parallel-walled dental implants: A systematic review and meta-analysis

BACKGROUND

Clinical trials have suggested that dental implants with a tapered configuration have improved stability at placement, allowing immediate placement and/or loading. The aim of this systematic review and meta-analysis was to evaluate the implant stability of tapered dental implants compared to standard parallel-walled dental implants.

MATERIALS AND METHODS

Applying the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, randomized controlled trials (RCTs) were searched for in electronic databases and complemented by hand searching. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool and data were analyzed using statistical software.

RESULTS

A total of 1199 studies were identified, of which, five trials were included with 336 dental implants in 303 participants. Overall meta-analysis showed that tapered dental implants had higher implant stability values than parallel-walled dental implants at insertion and 8 weeks but the difference was not statistically significant. Tapered dental implants had significantly less marginal bone loss compared to parallel-walled dental implants. No significant differences in implant failure rate were found between tapered and parallel-walled dental implants.

CONCLUSIONS

There is limited evidence to demonstrate the effectiveness of tapered dental implants in achieving greater implant stability compared to parallel-walled dental implants. Superior short-term results in maintaining peri-implant marginal bone with tapered dental implants are possible. Further properly designed RCTs are required to endorse the supposed advantages of tapered dental implants in immediate loading protocol and other complex clinical scenarios.