Primary stability of implant placement and loading related to dental implant materials and designs: A literature review

Nanofeatured surfaces in dental implants: contemporary insights and impending challenges

Dental implant therapy, established as standard-of-care nearly three decades ago with the advent of microrough titanium surfaces, revolutionized clinical outcomes through enhanced osseointegration. However, despite this pivotal advancement, challenges persist, including prolonged healing times, restricted clinical indications, plateauing success rates, and a notable incidence of peri-implantitis. This review explores the biological merits and constraints of microrough surfaces and evaluates the current landscape of nanofeatured dental implant surfaces, aiming to illuminate strategies for addressing existing impediments in implant therapy. Currently available nanofeatured dental implants incorporated nano-structures onto their predecessor microrough surfaces. While nanofeature integration into microrough surfaces demonstrates potential for enhancing early-stage osseointegration, it falls short of surpassing its predecessors in terms of osseointegration capacity. This discrepancy may be attributed, in part, to the inherent "dichotomy kinetics" of osteoblasts, wherein increased surface roughness by nanofeatures enhances osteoblast differentiation but concomitantly impedes cell attachment and proliferation. We also showcase a controllable, hybrid micro-nano titanium model surface and contrast it with commercially-available nanofeatured surfaces. Unlike the commercial nanofeatured surfaces, the controllable micro-nano hybrid surface exhibits superior potential for enhancing both cell differentiation and proliferation. Hence, present nanofeatured dental implants represent an evolutionary step from conventional microrough implants, yet they presently lack transformative capacity to surmount existing limitations. Further research and development endeavors are imperative to devise optimized surfaces rooted in fundamental science, thereby propelling technological progress in the field.

Characteristics and biological responses of selective laser melted Ti6Al4V modified by micro-arc oxidation

Background/purpose

Additive manufacturing (AM) technology, such as selective laser melting (SLM), has been used to fabricate medical devices of Ti-6wt.% Al-4wt.%V (Ti6Al4V) alloys in dentistry. Strontium (Sr) has been shown to have the potential to treat osteoporosis. The aim of this study was to investigate the physicochemical and biological properties of strontium-containing coatings on selective laser melted Ti6Al4V (SLM-Ti6Al4V) substrate.

Materials and methods

The disk of Ti6Al4V was prepared by SLM method. The strontium-containing coatings were prepared by micro-arc oxidation (MAO) in aqueous electrolytes. The surface topography, chemical composition, and phase of strontium-containing MAO (SrMAO) coatings were performed by scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS), and thin film X-ray diffraction (TF-XRD), respectively. The apatite-forming ability of the MAO coatings was conducted in simulating body fluid (SBF), and the cell proliferation was determined by methylthiazoletetrazolium (MTT) assay.

Results

The microstructure of SLM-Ti6Al4V displays acicular α-phase organization. The TF-XRD results indicated that the phase of SrMAO coating was anatase, rutile, and titanium. The calcium, phosphorus, and strontium were detected in the coatings by EDS. Using the SEM, the surface morphology of SrMAO coatings exhibited a uniform 3D porous structure. The SrMAO coatings could induce a bone-like apatite layer after immersion in SBF, and presented significantly higher cell proliferation than untreated specimens in in-vitro experiments.

Conclusion

All findings in this study indicate that SrMAO coatings formed on SLM-Ti6Al4V surfaces exhibit a benefit on biological responses and thereby are suitable for biomedical applications.

Exploring the effect of chlorhexidine concentration on the biocorrosion behavior of Ti6Al4V for dental implants

Corrosion of dental implants is one of the most critical factors in the failure of implant treatments. Generally, corrosion depends on the type of material used in implants and the chemical composition of the oral environment. Due to the antibacterial activities, mouthwashes and chlorhexidine gels are often used after implant surgery. Ti6Al4V is commonly used in manufacturing dental implants. The present study aims to investigate the corrosion behavior of the Ti6Al4V alloy under different concentrations of chlorhexidine (0.12%, 0.2%,and 2%) during 2- and 24-h immersion. This way corrosion may be minimized while obtaining an antibacterial environment around the implant. In this regard, the electrochemical behavior of the specimens was investigated using polarization and impedance tests, and then their morphology, cross-section and nano-tribological behavior were evaluated using atomic force microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and nano-scratch test. The results show that using chlorhexidine solution with a concentration of 0.12% could yield a lower corrosion rate and material loss after implant surgery. RESEARCH HIGHLIGHTS: Open circuit potential values increase with immersion time, which suggests multistage passivation of the surface during immersion in chlorhexidine. Specimens in 0.12% chlorhexidine show improved thermodynamic corrosion resistance. Nano-scratch testing demonstrates higher scratch resistance for specimens in 0.12% chlorhexidine solution after 2-h immersion. Higher chlorhexidine concentration than 0.12% and longer immersion times decrease the resistance of the formed passive layer.

Radiographic and histologic assessment of osseointegration for surface-treated titanium dental implants: An experimental study in dogs

Background

Modifying the dental implant's surface texture enhances its biological response to the bone and implant‒tissue interface, resulting in the successful support of forces. This study assessed the impact of sandblasting, sandblasting plus acid etching, Er,Cr:YSGG laser, and propolis implant surface treatments and occlusal load on the osseointegration of titanium dental implants in dogs.

Methods

Seventy-two titanium dental implants with a diameter of 4 mm and a length of 10 mm were divided into four groups according to implant surface modifications (n=18 for each group): group A: sandblasting plus acid etching, group B: sandblasting with Al2 O3, group C: Er,Cr:YSGG laser, group D: propolis coating. Twenty-four local breed male dogs were used. Premolar teeth (P1, P2, and P3) were extracted on the left side of the mandible, and after 12 weeks of bone healing, implants were unilaterally installed. The osseointegration at three study times from implant installation (14, 90, and 180 days) was evaluated. The dog jaws were scanned using an intraoral scanner for the virtual design of screw-retained three-unit crowns after 90 days of osseointegration. Final radiographs were taken before the animals were sacrificed at 14, 90, and 180 days, and the histological analysis was performed.

Results

Radiographic analysis showed new bone formation (NBF) along and in contact with the implant surface of the treated groups. The histological analysis after 14 days in groups A and B revealed a uniform and ongoing pattern of bone growth and many osteoblasts with few osteocytes within lacunae in new bone trabeculae. Group C showed an increase in the number of osteoblasts lining thin bone trabeculae. Group D showed a generative power concerning bone. At 90 days, there was increased bone ingrowth, and the new bone matured in all the treated implant groups. At 180 days, dense mature bone apposition was in direct contact with delayed-loaded implant surfaces.

Conclusion

A radiographic examination revealed that surface modification significantly impacted osseointegration, with a strong bond between the implant surface and the surrounding bone. The histological sections at the 14-day interval revealed obvious bone remodeling activity, especially in sandblasting plus acid etching and sandblasting-modified implant surface groups. At the 90-day interval, bone ingrowth had increased, and the new bone became mature, especially in sandblasting and propolis surface modification groups. After 180 days of the delayed-loaded implant osseointegration, differences were observed between different implant-treated groups with a remarkable remodeling of the bone, especially in the propolis coating group.

Assessment of bone density in edentulous maxillae using cone beam computed tomography (CBCT)

INTRODUCTION

In edentulous maxillae, the anterior maxilla is the region of interest for implant placement due to posterior bone resorption and sinus pneumatization. This study aimed to assess variations in bone density in different regions of the edentulous maxilla according to sex and age, using cone beam computed tomography (CBCT).

MATERIALS AND METHODS

69 CBCT from edentulous maxilla were analyzed. Six virtual implants were planned between the maxillary sinuses at incisor, canine, and premolar sites. Bone densities (in Hounsfield units HU) were recorded at six points on the neck, body, and apex of the buccal and lingual areas of each virtual implant. We used the two-sample t-test to compare male and female bone densities, and the Spearman correlation coefficient to analyze the correlation between mean bone density and age. One-way analysis of variance with post hoc pairwise t-tests was used to analyze the differences in density between three sites of the edentulous maxilla and the differences in density between three parts of the implant. The significance level was set at 5%.

RESULTS

Mean bone density in males was significantly higher than in females. There was a significant correlation between mean bone density and age in females. Incisor sites showed the highest mean bone density, followed by canine and premolar sites. There was a significant decline in bone density from the neck to the apex.

CONCLUSIONS

Bone density varied within and among edentulous maxillae. Bone density of the edentulous maxilla seemed to be influenced by age in women and by sex.

Effect of different implant locations and abutment types on stress and strain distribution under non-axial loading: A 3-dimensional finite element analysis

Background/purpose

Dental implants have been a popular treatment for replacing missing teeth. The purpose of this study was to investigate the impact of engaging (hexagonal) and non-engaging (non-hexagonal) abutments in various six-unit fixed prosthesis on the stress distribution and loading located in the implant neck, implant abutment, and surrounding bone.

Materials and methods

Three implants were digitally designed and inserted parallel to each other in edentulous sites of the maxillary right canine, maxillary right central incisor, and maxillary left canine. Titanium base engaging abutments, non-engaging abutments and connecting screws were designed. Five distinct models of 6-unit fixed dental prosthesis were created, each featuring different combinations of various abutments. Forces (45-degree angle) were applied to the prosthesis, allowing for the analysis of the stress distribution on the implant neck and abutments, and the maximum and minimum principal stress values on the cortical and trabecular bone.

Results

Von Mises stress values and stress distributions located in the implant neck region due to the applied loading forces were analyzed. The overall stress values were highest while employing the hexagonal abutments. The maxillary left canine with a hexagonal abutment (model 5) reported the highest von mises value (64.71 MPa) while the maxillary right canine with a non-hexagonal abutment (model 4) presented lowest von mises value (56.69 MPa).

Conclusion

The results suggest that both the various abutment combinations (engaging and non-engaging) on five different models have a similar influence on the distribution of stress within the implant system.