Osseointegration of SLActive implants in diabetic pigs

Osseointegration of implant surfaces in metabolic syndrome and type-2 diabetes mellitus

This in vivo study evaluated the bone healing response around endosteal implants with varying surface topography/chemistry in a preclinical, large transitional model induced with metabolic syndrome (MS) and type-2 diabetes mellitus (T2DM). Fifteen Göttingen minipigs were randomly distributed into two groups: (i) control (normal diet, n = 5) and (ii) O/MS (cafeteria diet for obesity induction, n = 10). Following obesity induction, five minipigs from the obese/metabolic syndrome (O/MS) group were further allocated, randomly, into the third experimental group: (iii) T2DM (cafeteria diet + streptozotocin). Implants with different surface topography/chemistry: (i) dual acid-etched (DAE) and (ii) nano-hydroxyapatite coating over the DAE surface (NANO), were placed into the right ilium of the subjects and allowed to heal for 4 weeks. Histomorphometric evaluation of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO) within implant threads were performed using histomicrographs. Implants with NANO surface presented significantly higher %BIC (~26%) and %BAFO (~35%) relative to implants with DAE surface (%BIC = ~14% and %BAFO = ~28%, p < .025). Data as a function of systemic condition presented significantly higher %BIC (~28%) and %BAFO (~42%) in the control group compared with the metabolically compromised groups (O/MS: %BIC = 14.35% and %BAFO = 26.24%, p < .021; T2DM: %BIC = 17.91% and %BAFO = 26.12%, p < .021) with no significant difference between O/MS and T2DM (p > .05). Statistical evaluation considering both factors demonstrated significantly higher %BIC and %BAFO for the NANO surface relative to DAE implant, independent of systemic condition (p < .05). The gain increase of %BIC and %BAFO for the NANO compared with DAE was more pronounced in O/MS and T2DM subjects. Osseointegration parameters were significantly reduced in metabolically compromised subjects compared with healthy subjects. Nanostructured hydroxyapatite-coated surfaces improved osseointegration relative to DAE, regardless of systemic condition.

Dental implants in large animal models with experimental systemic diseases: A systematic review

This systematic review aims to identify and discuss the most used methodologies in pre-clinical studies for the evaluation of the implementation of dental implants in systemically compromised pigs and sheep. This study provides support and guidance for future research, as well as for the prevention of unnecessary animal wastage and sacrifice. Preferred Reporting for Systematic Reviews and Meta-Analyses (PRISMA) was used as a guideline; electronic searches were performed in PubMed, Scopus, Scielo, Web of Science, Embase, Science Direct, Brazilian Bibliography of Dentistry, Latin American and Caribbean Literature in Health Sciences, Directory of Open Access Journals, Database of Abstracts of Reviews of Effects, and gray literature until January 2022 (PROSPERO/CRD42021270119). Sixty-eight articles were chosen from the 2439 results. Most studies were conducted in pigs, mainly the Göttinger and Domesticus breeds. Healthy animals with implants installed in the jaws were predominant among the pig studies. Of the studies evaluating the effect of systemic diseases on osseointegration, 42% were performed in osteoporotic sheep, 32% in diabetic sheep, and 26% in diabetic pigs. Osteoporosis was primarily induced by bilateral ovariectomy and mainly assessed by X-ray densitometry. Diabetes was induced predominantly by intravenous streptozotocin and was confirmed by blood glucose analysis. Histological and histomorphometric analyses were the most frequently employed in the evaluation of osseointegration. The animal models presented unique methodologies for each species in the studies that evaluated dental implants in the context of systemic diseases. Understanding the most commonly used techniques will help methodological choices and the performance of future studies in implantology.

Osseointegration of implants with superhydrophilic surfaces in rats with high serum levels of nicotine

This study aimed to evaluate the effect of nicotine administration on the osseointegration of a superhydrophilic implants surface on rat tibiae. Thirty-two rats were used and divided into 2 groups according to the administration or not of nicotine: HH - Installation of implants with superhydrophilic surfaces in healthy animals; and HN - Installation of implants with superhydrophilic surfaces in animals subjected to nicotine administration. The animals were euthanized 15 and 45 days after implant placement (n = 8). Osseointegration was assessed by means of biomechanical analyses (removal torque), microcomputed tomography (volume of bone around the implants- %BV/TV), and histomorphometry (bone-implant contact -%BIC and the bone area between implant threads -%BBT). The animals subject to the nicotine administration presented lower removal torque than the control animals at the 45-day period (21.88 ± 2.80 Ncm vs. 17.88 ± 2.10 Ncm). The implants placed in the control rats presented higher %BIC (54.26 ± 6.59% vs. 39.25 ± 4.46%) and %BBT (50.57 ± 5.28% vs. 32.25 ± 5.24%) than the implants placed in nicotine animals at 15-day period. The nicotine administration reduces the osseointegration at 15 days, however, the superhydrophilic surface equalized the osseointegration in nicotine-exposed animals compared with healthy animals after 45 days of implant placement.

Involvement of PI3K/Akt signaling pathway in promoting osteogenesis on titanium implant surfaces modified with novel non-thermal atmospheric plasma

Non-thermal atmospheric plasma (NTAP) modification to induce a hydrophilic titanium (Ti) surface with less carbon contamination, has been demonstrated to boost the osteogenic responses. In this study, we investigated the underlying bone formation mechanism of NTAP-Ti, and the involvement of PI3K/Akt signaling pathway in regulating osteogenic activities on NTAP-Ti surfaces. NTAP was employed for Ti activation, and PI3K inhibitor, LY294002, was applied to the suppression of PI3K/Akt pathway. We systematically and quantitatively detected the cell morphology, attachment, proliferation, osteogenic differentiation and mineralization of MC3T3-E1 mouse preosteoblasts, and molecular expressions involved in osteogenesis and PI3K/Akt signaling pathway in vivo and in vitro. A descent in osteoblast proliferation on Ti surfaces in relation to LY294002. Alkaline phosphatase (ALP) activity, as well as matrix mineralization, was mitigated by PI3K inhibitor in NTAP-Ti. Likewise, the expression levels of osteogenesis-related genes [ALP, osteocalcin (Ocn), osteopontin (Opn) and runt-related transcription factor 2 (Runx2)] on NTAP-Ti were notably attenuated by LY294002, as confirmed by the results of osteogenesis-related proteins (ALP, and Runx2) expression analysis. In addition, the expression of PI3K/Akt signal pathway proteins further verified the inhibition of LY294002 on Ti surfaces modified by NTAP. Collectively, the PI3K/Akt signal pathway was involved in the amelioration of osteogenesis induced by NTAP modification. NTAP treatment for Ti activation is promising in augmented osteogenic potential through the activation of PI3K/Akt signal pathway.

Hormone and implant osseointegration: Elaboration of the relationship among function, preclinical, and clinical practice

As clusters of peptides or steroids capable of high-efficiency information transmission, hormones have been substantiated to coordinate metabolism, growth, development, and other physiological processes, especially in bone physiology and repair metabolism. In recent years, the application of hormones for implant osseointegration has become a research hotspot. Herein, we provide a comprehensive overview of the relevant reports on endogenous hormones and their corresponding supplementary preparations to explore the association between hormones and the prognosis of implants. We also discuss the effects and mechanisms of insulin, parathyroid hormone, melatonin, vitamin D, and growth hormone on osseointegration at the molecular and body levels to provide a foothold and guide future research on the systemic conditions that affect the implantation process and expand the relative contraindications of the implant, and the pre-and post-operative precautions. This review shows that systemic hormones can regulate the osseointegration of oral implants through endogenous or exogenous drug-delivery methods.

Evaluation of Bone Response to a Nano HA Implant Surface on Sinus Lifting Procedures: Study in Rabbits

The aim of this study was to evaluate the bone response to two different implant surfaces on sinus lift procedures in rabbits. Bilateral sinus lifting with inorganic bovine bone associated with collagen membrane and immediate implantation were performed in 16 rabbits. Custom mini-implants were randomly installed in the prepared sites: one side received a double acid-etched (DAE) surface and the other a nano-hydroxyapatite (NHA) surface. The animals were euthanized 30 and 60 days after surgery, and biopsies were collected for microtomographic and histomorphometric analysis. After 30 days, no intra- and inter-group statistical differences were observed in microtomographic analysis, while at 60 days, bone analysis showed statistically significant differences between groups (p < 0.05) for all the evaluated parameters. Histomorphometric analysis showed, after 30 days, mean % of Bone-to-Implant Contact (BIC) for DAE and NHA of 31.70 ± 10.42% vs. 40.60 ± 10.22% (p > 0.05), respectively; for % of Bone Area Fraction Occupancy (BAFO), mean values were 45.43 ± 3.597% for DAE and 57.04 ± 5.537% for NHA (p < 0.05). After 60 days, mean %BIC and %BAFO for DAE and NHA implants were statistically significant (p < 0.05). The NHA surface showed superior biological features compared to the DAE treatment, promoting higher bone formation around the implants in an experimental model of bone repair in a grafted area.

Implant stability of narrow diameter implants in hyperglycemic patients-A 3-month case-control study

OBJECTIVES

The aim of this prospective case-control study was to compare the development of implant stability quotients of narrow diameter implants in patients with type 2 diabetes mellitus (T2DM) and healthy individuals within the first 3 months after implant insertion.

METHODS

Sixteen patients with T2DM (HbA1C > 6.5%) as test group and 16 nondiabetic patients (HbA1C < 5.9%) as the control group were evaluated. All patients received narrow-diameter tissue level implants in an edentulous area posterior to the canine. The implant stability was measured by means of resonance frequency analysis after 3 days, 7 days, 4 weeks, and 3 months postplacement. Statistical analysis of intergroup differences and correlation to HbA1c values and treated jaw was performed in PRISM 8.

RESULTS

The means for implant stability quotients showed a significant increase between Day 3 and 3-month assessment in both groups. No significant differences between study groups and no correlation of implant stability to HbA1c were found.

CONCLUSION

The present study shows encouraging clinical outcomes for narrow-diameter implants inserted in the posterior zone in patients with uncontrolled T2DM.

One-year performance of posterior narrow diameter implants in hyperglycemic and normo-glycemic patients-a pilot study

OBJECTIVES

The aim of the study was to compare the performance of narrow diameter implants in patients with uncontrolled diabetes mellitus type 2 (T2DM) and normo-glycemic individuals during the first 12 months after implant loading.

MATERIAL AND METHODS

In 16 T2DM patients with HbA1C > 6.5% (test group) and 16 normo-glycemic patients (HbA1C < 6.0%; control group), one to two narrow diameter tissue level implants were placed in the posterior maxilla or mandible. After 3-month lasting integration period, implants were loaded by fixed dentures. The clinical parameters probing depth (PD), bleeding on probing (BOP), attachment loss (CAL), recession and papilla bleeding index (PBI) were assessed manually at loading and after 12 months of function. The paired digital periapical radiographs were analyzed with regard to the change in marginal bone level (MBL) from baseline to 12 months' control. The mean values calculated for both patient groups were statistically analyzed. The technical complications were recorded.

RESULTS

The T2DM group accounted 13 patients due to 3 dropouts. The overall implant survival rate after 12 months was 100%. The differences in means for the clinical parameters and the MBL were statistically non-significant between the T2DM and normo-glycemic patients for the short period of loaded function reported here. No technical complications were recorded.

CONCLUSIONS

The study demonstrated an encouraging clinical outcome with narrow diameter implants in patients with uncontrolled T2DM compared to non-diabetics after 12 months post loading. For the short observation period, no biological and technical complications were reported regardless the glycemic status.

CLINICAL RELEVANCE

Patients with HbA1C > 6.5% may benefit from the treatment with narrow diameter implants by avoiding complex surgical interventions with augmentation procedures.

TRIAL REGISTRATION

Clinicaltrials.gov : NCT04630691.

Clinical performance of hydrophilic, titanium-zirconium dental implantsin patients with well-controlled and poorly-controlledtype 2 diabetes: One-Year results of a dual-centerprospectivecohort study

BACKGROUND

This study assessed the clinical performance of hydrophilic dental implants in a patient cohort with type 2 diabetes mellitus (T2DM).

METHODS

Subjects with T2DM of ≥ 2-years duration were allocated to either the well-controlled (WC; HbA1c ≤ 7.0%,) or poorly-controlled (PC; 7.5 < HbA1c < 10%) groups in a dual-center, prospective cohort study. Each subject received a single, titanium-zirconium (Ti-Zr) dental implant with a chemically-modified, hydrophilic (modSLA) surface in a posterior mandibular site. Postoperatively, subjects were followed at 1, 2, 4, 8 and 12-week intervals. Post-loading, subjects were followed at 3, 6 and 12-months. Clinical and radiographic parameters of implant success, and dental patient-reported outcomes were collected.

RESULTS

Twenty-one dental patients (N_WC = 11; N_PC = 10; mean age: 66.8 ± 7.5 years) were enrolled and the 1-year implant success rate was 100%. Peri-implant bone levels were stable with 0.15 ± 0.06 mm mean marginal loss at one year without significant inter-group differences (p = 0.79). Postoperative pain was minimal at 1-week, and OHIP-5 scores decreased significantly over time as compared with preoperative levels (p < 0.001) suggesting significant improvement in patient-perceived oral health following implant therapy.

CONCLUSIONS

Elevated HbA1c levels> 7.5% did not compromise 1-year successrates, or oral health-related quality of lifein PC patients receiving modSLA, Ti-Zr implants. This article is protected by copyright. All rights reserved.

Pre-Clinical Models in Implant Dentistry: Past, Present, Future

Biomedical research seeks to generate experimental results for translation to clinical settings. In order to improve the transition from bench to bedside, researchers must draw justifiable conclusions based on data from an appropriate model. Animal testing, as a prerequisite to human clinical exposure, is performed in a range of species, from laboratory mice to larger animals (such as dogs or non-human primates). Minipigs appear to be the animal of choice for studying bone surgery around intraoral dental implants. Dog models, well-known in the field of dental implant research, tend now to be used for studies conducted under compromised oral conditions (biofilm). Regarding small animal models, research studies mostly use rodents, with interest in rabbit models declining. Mouse models remain a reference for genetic studies. On the other hand, over the last decade, scientific advances and government guidelines have led to the replacement, reduction, and refinement of the use of all animal models in dental implant research. In new development strategies, some in vivo experiments are being progressively replaced by in vitro or biomaterial approaches. In this review, we summarize the key information on the animal models currently available for dental implant research and highlight (i) the pros and cons of each type, (ii) new levels of decisional procedures regarding study objectives, and (iii) the outlook for animal research, discussing possible non-animal options.

Osteoblast Attachment Compromised by High and Low Temperature of Titanium and Its Restoration by UV Photofunctionalization

Titanium implants undergo temperature fluctuations during manufacturing, transport, and storage. However, it is unknown how this affects their bioactivity. Herein, we explored how storage (six months, dark conditions) and temperature fluctuations (5-50 °C) affected the bioactivity of titanium implants. Stored and fresh acid-etched titanium disks were exposed to different temperatures for 30 min under wet or dry conditions, and their hydrophilicity/hydrophobicity and bioactivity (using osteoblasts derived from rat bone marrow) were evaluated. Ultraviolet (UV) treatment was evaluated as a method of restoring the bioactivity. The fresh samples were superhydrophilic after holding at 5 or 25 °C under wet or dry conditions, and hydrophilic after holding at 50 °C. In contrast, all the stored samples were hydrophobic. For both fresh and stored samples, exposure to 5 or 50 °C reduced osteoblast attachment compared to holding at 25 °C under both wet and dry conditions. Regression analysis indicated that holding at 31 °C would maximize cell attachment (p < 0.05). After UV treatment, cell attachment was the same or better than that before temperature fluctuations. Overall, titanium surfaces may have lower bioactivity when the temperature fluctuates by ≥20 °C (particularly toward lower temperatures), independent of the hydrophilicity/hydrophobicity. UV treatment was effective in restoring the temperature-compromised bioactivity.

The osseointegration and stability of dental implants with different surface treatments in animal models: a network meta-analysis

Dental implants are commonly used to repair missing teeth. The implant surface plays a critical role in promoting osseointegration and implant success. However, little information is available about which implant surface treatment technology best promotes osseointegration and implant stability. The aim of this network meta-analysis was to evaluate the osseointegration and stability of four commonly used dental implants (SLA, SLActive, TiUnite, and Osseotite). The protocol of the current meta-analysis is registered in PROSPERO (International Prospective Register of Systematic Reviews) under the code CRD42020190907 (https://www.crd.york.ac.uk). We conducted a systematic review following PRISMA and Cochrane Recommendations. Medline (PubMed), Cochrane Library, Embase, and the Web of Science databases were searched. Only randomized controlled trials were considered. Twelve studies were included in the current network meta-analysis, eleven studies were included concerning the osseointegration effect and five studies were included for stability analysis (four studies were used to assess both stability and osseointegration). Rank possibility shows that the SLActive surface best promoted bone formation at an early healing stage and TiUnite seemed to be the best surface for overall osseointegration. For stability, TiUnite seemed to be the best surface. The present network meta-analysis showed that the SLActive surface has the potential to promote osseointegration at an early stage. The TiUnite surface had the best effect on osseointegration regarding the overall healing period. The TiUnite surface also had the best effect in stability.

Histomorphometric analysis of implant osseointegration using hydrophilic implants in diabetic rats

OBJECTIVES

To evaluate peri-implant bone formation of titanium implants using an in vivo rat model with and without uncontrolled diabetes mellitus (DM) to evaluate osseointegration of hydrophobic (Neoporos®) and hydrophilic (Acqua®) surfaces.

MATERIALS AND METHODS

54 rats were divided into two groups: DM group (DMG) (streptozotocin-induced diabetes) and a control group (CG). Implants with hydrophobic (Neoporos®) and hydrophilic surfaces (Acqua®) were placed in the left or right tibia of animals. Animals were further divided into three groups (n = 9) euthanized after 7, 14, or 28 days. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were assessed in total, cortical, and medullary areas.

RESULTS

The DMG group, after a 7-day healing period, yielded with the Acqua implants presented significantly higher total BIC (+37.9%; p=0.03) and trabecular BIC (%) (+46.3%; p=0.02) values in comparison to the Neoporos implants. After 28 days of healing, the CG yielded that the cortical BAFO of Acqua implants to be significantly, 14%, higher (p=0.04) than Neoporos implants.

CONCLUSION

The positive effects of the Acqua surface were able to counteract the adverse impact of uncontrolled DM at early osseointegration periods. After 28 days in vivo, the metabolic systemic impairment caused by DM overcame the surface treatment effect, leading to impaired osseointegration in both hydrophilic and hydrophobic implants.

CLINICAL RELEVANCE

The adverse effects of diabetes mellitus with respect to bone healing may be minimized by deploying implants with strategically modified surfaces. This study evaluated the effects of implants with Acqua® and Neoporos® surfaces in both diabetic and healthy animals. During the initial healing period in diabetic animals, the hydrophilic surface was demonstrated to have beneficial effect on osseointegration in comparison to the hydrophobic surface. The results provide an insight into early healing, but the authors suggest that a future short-term and long-term clinical study is needed to assess the possible benefit of the Acqua® implant as well as in increasing the predictability of implant osseointegration.

Zoledronate Causes a Systemic Shift of Macrophage Polarization towards M1 In Vivo

BACKGROUND

Immunomodulatory properties of bisphosphonates (BP) are suggested to contribute to the development of medication-associated osteonecrosis of the jaw (MRONJ). Furthermore, bisphosphonate-derived immune modulation might contribute to the anti-metastatic effect observed in breast cancer patients. Macrophages are potential candidates for the mediation of immunomodulatory effects of bisphosphonates. The study aimed to investigate the influence of bisphosphonates alone and in combination with surgical trauma on systemic macrophage polarization (M1 vs. M2) using an in vivo rat model.

METHODS

A total of 120 animals were divided into four groups. Groups 2 and 4 were treated with 8 × 40 μg/kg body weight of the BP Zoledronate i.p. (week 0-7). Groups 3 and 4 were exposed to surgical trauma (week 8, tooth extraction + tibia fracture), whereas in Group 1 neither medication nor surgical trauma was applied. After 8, 10, 12 and 16 weeks, skin, lung and spleen were immunohistochemically examined for macrophage polarization via expression analysis of CD68, CD163 and iNOS using a tissue microarray (TMA).

RESULTS

A significant shift of macrophage polarization towards M1 was observed in skin, spleen and lung tissue of animals, with and without surgical trauma, treated with BP when compared to those without BP application. Surgical trauma did not cause a significant increase towards M1 polarization.

CONCLUSIONS

BP application leads to a systemic pro-inflammatory situation in vivo, independent of surgical trauma, as evidenced by the shift in macrophage polarization towards M1 in various somatic tissues. This provides a possible explanation for the clinically observed anti-tumor effect of bisphosphonates and might also contribute to pathogenesis of MRONJ.

Histological and Nanomechanical Properties of a New Nanometric Hydroxiapatite Implant Surface. An In Vivo Study in Diabetic Rats

Implant therapy is a predictable treatment to replace missing teeth. However, the osseointegration process may be negatively influenced by systemic conditions, such as diabetes mellitus (DM). Microtopography and implant surface developments are strategies associated to better bone repair. This study aimed to evaluate, in healthy and diabetic rats, histomorphometric (bone to implant contact = %BIC; and bone area fraction occupancy = %BAFO) and nanomechanical (elastic modulus = EM; and hardness = H) bone parameters, in response to a nanometric hydroxyapatite implant surface. Mini implants (machined = MAC; double acid etched = DAE, and with addition of nano-hydroxyapatite = NANO) were installed in tibias of healthy and diabetic rats. The animals were euthanized at 7 and 30 days. NANO surface presented higher %BIC and %BAFO when compared to MAC and DAE (data evaluated as a function of implant surface). NANO surface presented higher %BIC and %BAFO, with statistically significant differences (data as a function of time and implant surface). NANO surface depicted higher EM and H values, when compared to machined and DAE surfaces (data as a function of time and implant surface). Nano-hydroxyapatite coated implants presented promising biomechanical results and could be an important tool to compensate impaired bone healing reported in diabetics.

Re-establishment of macrophage homeostasis by titanium surface modification in type II diabetes promotes osseous healing

Titanium surface mediated immunomodulation may address compromised post-implantation bone healing in diabetes mellitus. To assess in vitro phenotypic changes, M1 and M2 polarised Type 2 diabetic rat (Goto Kakizaki, GK) macrophages were cultured on micro-rough (SLA) or hydrophilic nanostructured SLA (modSLA) titanium. The in vivo effects of the SLA and modSLA surfaces on macrophage phenotype, wound-associated protein expression and bone formation were investigated using a critical-sized calvarial defect model. Compared to healthy macrophages, GK M2 macrophage function was compromised, secreting significantly lower levels of the anti-inflammatory cytokine IL-10. The modSLA surface attenuated the pro-inflammatory cellular environment, reducing pro-inflammatory cytokine production and promoting M2 macrophage phenotype differentiation. ModSLA also suppressed gene expression associated with macrophage multinucleation and giant cell formation and stimulated pro-osteogenic genes in co-cultured osteoblasts. In vivo, modSLA enhanced osteogenesis compared to SLA in GK rats. During early healing, proteomic analysis of both surface adherent and wound exudate material showed that modSLA promoted an immunomodulatory pro-reparative environment. The modSLA surface therefore successfully compensated for the compromised M2 macrophage function in Type 2 diabetes by attenuating the pro-inflammatory response and promoting M2 macrophage activity, thus restoring macrophage homeostasis and resulting in a cellular environment favourable for enhanced osseous healing.

Influence of nano-hydroxyapatite coating implants on gene expression of osteogenic markers and micro-CT parameters. An in vivo study in diabetic rats

This study evaluated the response of a nano-hydroxyapatite coating implant through gene expression analysis (runt-related transcription factor 2 (Runx2), alkaline phosphatase (Alp), osteopontin (Opn), osteocalcin (Oc), receptor activator of nuclear factor-kappa B (Rank), receptor activator of nuclear factor-kappa B ligand (Rank-L), and osteoprotegerin (Opg)). Three-dimensional evaluation (percent bone volume (BV/TV); percent intersection surface (BIC); bone surface/volume ratio (BS/BV); and total porosity (To.Po)) were also analyzed. Mini implants were surgically placed in tibias of both healthy and diabetic rats. The animals were euthanized at 7 and 30 days. Evaluating all factors the relative expression of Rank showed that NANO surface presented the best results at 7 days (diabetic rats). Furthermore the levels of Runx2, Alp, Oc, and Opn suggest an increase in osteoblasts proliferation, especially in early stages of osseointegration. %BIC in healthy and diabetic (7 days) depicted statistically significant differences for NANO group. BV/TV, BS/BV and To.Po demonstrated higher values for NANO group in all evaluated time point and irrespective of systemic condition, but BS/BV 30 days (healthy rat) and 7 and 30 days (diabetic rat). Microtomographic and gene expression analyses have shown the benefits of nano-hydroxyapatite coated implants in promoting new bone formation in diabetic rats.

Clinical performance of titanium-zirconium implants with a hydrophilic surface in patients with controlled type 2 diabetes mellitus: 2-year results from a prospective case-control clinical study

OBJECTIVE

Analyze the 2-year clinical performance of single-unit titanium-zirconium (TiZr) alloy narrow-diameter (3.3 mm) dental implants with a hydrophilic surface (Straumann® Roxolid®, SLActive®) in patients with controlled type 2 diabetes mellitus (T2DM), measured using the glycated hemoglobin A (HbA1c) concentration test, compared with results in individuals without T2DM.

MATERIAL AND METHODS

The studied sample consisted of 28 patients, 14 with T2DM (study group) and 14 without (control group). The plaque index, bleeding on probing, probing depth, clinical attachment level, gingival biotype, and marginal bone loss (MBL) at the site of the implants were assessed. HbA1c levels were assessed in all patients during each checkup.

RESULTS

Two years after implant placement and prosthetic restoration no implant failures were reported in either group, resulting in 100% survival and success rates in both groups. No statistically significant differences in MBL were found between the control and study groups (p > 0.05).

CONCLUSIONS

Within the limitations of this study, it can be concluded that reduced-diameter TiZr alloy implants with a hydrophilic surface represent a safe and predictable treatment option for patients with well-controlled T2DM. The clinical performance was comparable with that observed in individuals without T2DM in the medium term.

CLINICAL RELEVANCE

The narrow implants placed in patients with T2DM with well-controlled glycemia (HbA1c) showed a marginal bone loss and success and survival rates similar to those of the control group without DM2, in the medium term.

The Influence of Type 2 Diabetes Mellitus on the Osseointegration of Titanium Implants With Different Surface Modifications-A Histomorphometric Study in High-Fat Diet/Low-Dose Streptozotocin-Treated Rats

OBJECTIVES

Type 2 diabetes mellitus (T2DM) is a systemic disease that also compromises the bone healing capacity. In healthy individuals, surface modifications of dental implants are proven to increase bone response and implant success. The aim of this study was to clarify if the surface modifications also improve osseointegration in a setting with diabetes mellitus.

METHODS

T2DM was induced in 7 rats by a high-fat diet/low-dose streptozotocin injection. All animals received a hydroxyapatite (HA) implant, a sandblasted and acid-etched (SLA) implant, and a standard machined titanium implant for control in the tibia. After 4 weeks, thin-ground sections were produced, and the volume of new bone formation (nBV/TV) and bone-to-implant contact (nB.I/Im.I) were histomorphometrically analyzed.

RESULTS

Both surface modifications led to an increase of osseointegration compared with the machined surface implant in rats with T2DM. nBV/TV was highest in the SLA implants, whereas nB.I/Im.I was highest in the HA group. Regardless of the surface modification, a superordinate regional pattern of new bone formation over the length of the implant was observed.

CONCLUSIONS

Implants with HA coating and SLA surface modifications seem to have the potential to increase osseointegration also in T2DM rats when compared with a conventional machined surface.

Therapeutic Effects of HIF-1α on Bone Formation around Implants in Diabetic Mice Using Cell-Penetrating DNA-Binding Protein

Patients with uncontrolled diabetes are susceptible to implant failure due to impaired bone metabolism. Hypoxia-inducible factor 1α (HIF-1α), a transcription factor that is up-regulated in response to reduced oxygen during bone repair, is known to mediate angiogenesis and osteogenesis. However, its function is inhibited under hyperglycemic conditions in diabetic patients. This study thus evaluates the effects of exogenous HIF-1α on bone formation around implants by applying HIF-1α to diabetic mice and normal mice via a protein transduction domain (PTD)-mediated DNA delivery system. Implants were placed in the both femurs of diabetic and normal mice. HIF-1α and placebo gels were injected to implant sites of the right and left femurs, respectively. We found that bone-to-implant contact (BIC) and bone volume (BV) were significantly greater in the HIF-1α treated group than placebo in diabetic mice (p < 0.05). Bioinformatic analysis showed that diabetic mice had 216 differentially expressed genes (DEGs) and 21 target genes. Among the target genes, NOS2, GPNMB, CCL2, CCL5, CXCL16, and TRIM63 were found to be associated with bone formation. Based on these results, we conclude that local administration of HIF-1α via PTD may boost bone formation around the implant and induce gene expression more favorable to bone formation in diabetic mice.

Retrospective cohort study of a tapered implant with high primary stability in patients with local and systemic risk factors-7-year data

Objectives

This retrospective study examined the mid- to long-term clinical and radiographic performance of a tapered implant in various treatment protocols in patients with local and systemic risk factors (RFs).

Material and methods

Two hundred seven NobelActive implants were inserted in 98 patients in the period from 10/2008 to 02/2015. The subdivision of the cohort was defined by local (n = 40), systemic (n = 6), local and systemic (n = 8), or without any RFs (n = 44) to analyze implant survival and marginal bone levels.

Results

Fifteen implants failed within the follow-up period. The mean follow-up period of the remaining implants was 34 months (range 12 to 77 months). The cumulative survival rate according to Kaplan-Meier was 91.5%. The survival rate for 93 implants in 45 patients with no RFs was 94.8% whereas it was 94% for 83 implants in 48 patients with local RFs (p = 0.618), 81.3% for 14 implants in 6 patients with systemic RFs (p = 0.173), and 76.5% for 17 implants in 6 patients with local and systemic risk factors (p = 0.006). The interproximal marginal bone level was − 0.49 ± 0.83 mm at the mesial aspect and − 0.51 ± 0.82 mm at the distal aspect in relation to implant shoulder level and showed no relevant difference in the various risk factor groups.

Conclusions

It can be assumed that the negative effects of the local or/and systemic risk factors were partially compensated by the primary stability and grade of osseointegration of the NobelActive implant.

Clinical relevance

The use of this system in patients with risk factors and immediate loading procedures.

Effect of Obesity or Metabolic Syndrome and Diabetes on Osseointegration of Dental Implants in a Miniature Swine Model: A Pilot Study

PURPOSE

The increasing prevalence of obesity or metabolic syndrome (O/MS) and type 2 diabetes mellitus (DM) remains a global health concern. Clinically relevant and practical translational models mimicking human characteristics of these conditions are lacking. This study aimed to demonstrate proof of concept of the induction of stable O/MS and type 2 DM in a Göttingen minipig model and validate both of these disease-adjusted Göttingen minipig models as impaired healing models for the testing of dental implants.

MATERIALS AND METHODS

Nine minipigs were split into 3 groups-control (normal diet), obese (cafeteria diet), and diabetic (cafeteria diet plus low-dosage streptozotocin)-followed by placement of dental implants. Inflammatory markers including tumor necrosis factor α, C-reactive protein, and cortisol were recorded for each study group. Removal torque was measured, and histomorphometric analysis (bone-to-implant contact and bone area fraction occupancy) was performed.

RESULTS

O/MS pigs showed, on average, a 2-fold increase in plasma C-reactive protein (P < .05) and cortisol (P < .09) concentrations compared with controls; DM pigs showed, on average approximately, a 40-fold increase in plasma tumor necrosis factor α levels (P < .05) and a 2-fold increase in cortisol concentrations (P < .05) compared with controls. The impact of O/MS and DM on implants was determined. The torque to interface failure was highest in the control group (200 N-cm) and significantly lower in the O/MS (90 N-cm) and DM (60 N-cm) groups (P < .01). Bone formation around implants was significantly greater in the control group than in the O/MS and DM groups (P < .02).

CONCLUSIONS

Both O/MS and DM minipigs express a human-like disease phenotype, and both presented bone-healing impairment around dental implants. Our finding of no significant difference between type 2 DM and O/MS in bone formation around implants provides evidence that further investigation of the impact of O/MS is warranted.

The effect of plasma treatment on the osseointegration of rough titanium implant: A histo-morphometric study in rabbits

Abstract Background/purpose

The surface properties, such as hydrophilicity and functional OH groups, play an important role in bone fixation in vivo. In our previous study, the plasma treatments of large grit and acid etching (SLA) method produce functional OH groups on the rough surface. There is no report in discussing the integration between basic Ti—OH groups and bone-to-implant contact (BIC). The aim of this study was to evaluate the effect of the functional OH groups on the rough surface both in vitro and in vivo.

Materials and methods

Functional hydroxyl groups were produced on a SLA-treated surface. The surface topography, roughness, wettability, and chemical composition were examined using various techniques. Twenty-four implants were inserted into the proximal tibia of four New Zealand white rabbits. The biological responses were measured in terms of histomorphometric analysis 4 and 8 weeks post-implantation.

Results

The surface morphology and roughness were similar among all groups. However, the concentration of OH groups and hydrophilicity were found increased in the plasma treatment. The cell morphology in RF-plasma treated groups had more polygonal type and higher expression of actin and vinculin. The bone-to-implant contact (BIC) ratios of RF-200W were significantly higher than other groups (P < 0.05). The relationship between basic OH groups and BIC showed linear correspondence.

Conclusion

The Ti—OH groups introduced on the rough surface by plasma treatments can trigger cell adhesion which further initiate new bone apposition. We propose that RF-plasma treatment can help to enhance bone healing at 4 and 8 weeks.

The Effects of Hierarchical Micro/Nano-Structured Titanium Surface on Osteoblast Proliferation and Differentiation Under Diabetic Conditions

PURPOSE

The aim of the present study was to mimic the hierarchical structure of bone tissues by simple sandblasting/acid-etching and anodization to investigate the effects of such surface characteristics on proliferation and differentiation of osteoblasts in high glucose concentrations. By the way, the effects of high glucose levels on osteoblast functions were tested.

METHODS

MC3T3-E1 cells cultured on sand-blasted and acid-etched (SLA) surface and nano-modified SLA (NMSLA) surface were subjected to normal serum (NS) and diabetic serum (DS), respectively. The surface characteristics were evaluated by scanning electron microscopy. Cell proliferation was assessed using MTT assay. The levels of alkaline phosphatase (ALP) activity and mineralization were measured and compared. Real-time polymerase chain reaction was applied to detect the expression levels of osteogenic genes.

RESULTS

NMSLA significantly increased cell proliferation at time points ranging from 3 to 7 days under both serums. Cells cultured on NMSLA surfaces displayed significantly higher ALP activities and mineralization. The expression levels of Runx2 (indicates runt-related protein 2), collagen I (COL1), and osteocalcin (OCN) were notably increased on NMSLA surface compared with SLA surface. Moreover, we found that high glucose increased osteoblast proliferation but decreased differentiation of osteoblast slightly.

CONCLUSION

The hierarchical micro/nano-structured titanium surface has a favorable biocompatibility on simultaneously improving osteoblast proliferation and differentiation in diabetic serum.

Clinical Performance of Narrow-Diameter Titanium-Zirconium Implants: A Systematic Review

PURPOSE

Implant-supported prosthetic rehabilitations are in constant augmentation in everyday dental practice. This is largely due to increasing demand from patients for fixed or implant-stabilized prosthesis, although they are frequently reticent to complex preimplant bone augmentation surgeries, whenever bone volume is lacking. Narrow-diameter implants (NDI; ≤3.5 mm) have been developed to offer relatively simple implant solutions in challenging bone-deficient sites. However, concerns regarding their mechanical properties have been raised. Special titanium-zirconium material (Ti-Zr), with superior mechanical resistance, compared with pure titanium alloys has been introduced into the market. The purpose of this systematic review was to determine the available data on clinical performance of Ti-Zr NDI.

MATERIALS AND METHODS

A literature search of all available clinical articles dealing with Ti-Zr NDI has been carried out. After including only prospective clinical trials, 14 papers were retrieved for thorough reviewing.

CONCLUSION

Short-term results from preliminary clinical reports are quite promising, although the number of published studies and the follow-up periods are still insufficient to determine the real benefit of this hybrid material compared with titanium, especially when using NDI.

Peri-implant defect regeneration in the diabetic pig: A preclinical study

OBJECTIVES

The study aims to establish a peri-implant dehiscence-type bone defect in a diabetic animal model of human bone repair and to quantify the influence of diabetes on peri-implant bone regeneration.

MATERIAL AND METHODS

Experimental diabetes was induced in three domestic pigs by streptozotocin. Three animals served as healthy controls. After 12 months four standardized peri-implant dehiscence bone defects were surgically created in the ramus mandibulae. The animals were sacrificed after 90 days. Samples were histologically analyzed to quantify new bone height (NBH), bone-to-implant-contact (BIC), area of newly formed bone (NFB), bone-density (BD), and bone mineralization (BM) in the prepared defect (-D) and in a local control region (-L).

RESULTS

After 90 days, diabetic animals revealed a significantly lower BIC (p = 0.037) and BD (p = 0.041) in the defect area (-D). NBH and BM-D differences within the groups were not significant (p > 0.05). Significant more NFB was measured in the healthy control group (p = 0.046). In the region of local bone BIC-L was significant less in the diabetic group (p = 0.028). In the local control region BD-L and BM-L was lower in the diabetic group compared to the healthy control animals (p > 0.05).

CONCLUSION

Histological evidence indicates impaired peri-implant defect regeneration in a diabetic animal model.

Establishment of a new pull-out strength testing method to quantify early osseointegration-An experimental pilot study

OBJECTIVES

The animal study aims to evaluate a new experimental model for measuring sole the influence of the surface characteristics independent from implant macro-design on the level of osseointegration by registering the pull-out strength needed for removal of experimental devices with different surfaces from artificial defects.

MATERIAL AND METHODS

Seventy-two test bodies (36 with the FRIADENT(®) plus surface, 36 with the P15/HAp biofunctionalized surface) were inserted in six adult domestic pigs with artificial calvarial defects. The experimental devices were designed to fit in the defects leaving a gap between the test body and the local bone. After 21 days of healing, the animals were sacrificed and the test bodies were pulled out with a standardised reproducible pull-out device measuring the pull-out strength. The pull-out strength for both groups was compared.

RESULTS

Twenty-one days after insertion a mean force of 412 ± 142 N for the P15/HAp group and 183 ± 105 N for the FRIADENT(®) plus group was measured for the removal of the specimens from the calvarial bone. The difference between the groups was statistically significant (p < 0.0001).

CONCLUSION

The experimental set-up seems to be a suitable method when measuring the impact of implant surfaces on the early stage of osseointegration.

Key systemic and environmental risk factors for implant failure

Dental implants are an important treatment option for patients interested in replacing lost or missing teeth. Although a robust body of literature has reviewed risk factors for tooth loss, the evidence for risk factors associated with dental implants is less well defined. This article focuses on key systemic risk factors relating to dental implant failure, as well as on perimucositis and peri-implantitis.

The effects of elevated hemoglobin A(1c) in patients with type 2 diabetes mellitus on dental implants: Survival and stability at one year

BACKGROUND

The authors conducted a prospective cohort study to determine whether poor glycemic control is a contraindication to implant therapy in patients with type 2 diabetes.

METHODS

The study sample consisted of 117 edentulous patients, each of whom received two mandibular implants, for a total of 234 implants. Implant-retained mandibular overdentures were loaded after a four-month healing period and followed up for an additional one year. The authors assessed implant survival and stability (by means of resonance frequency analysis) relative to glycated hemoglobin A1c (HbA1c) levels, with baseline levels up to 11.1 percent and levels as high as 13.3 percent over one year.

RESULTS

Implant survival rates for 110 of 117 patients who were followed up for one year after loading were 99.0 percent, 98.9 percent and 100 percent, respectively, for patients who did not have diabetes (n = 47), those with well-controlled diabetes (n = 44) and those with poorly controlled diabetes (n = 19). The authors considered the seven patients lost to follow-up as having had failed implants; consequently, their conservative estimates of survival rates in the three groups were 93.0 percent, 92.6 percent and 95.0 percent (P = .6510). Two implants failed at four weeks, one in the nondiabetes group and the other in the well-controlled diabetes group. Delays in implant stabilization were related directly to poor glycemic control.

CONCLUSIONS

The results of this study indicate that elevated HbA1c levels in patients with type 2 diabetes were not associated with altered implant survival one year after loading. However, alterations in early bone healing and implant stability were associated with hyperglycemia.

Bone formation in peri-implant defects grafted with microparticles: a pilot animal experimental study

AIM

This study aimed to evaluate the healing of peri-implant defects grafted with microparticles (MPs).

MATERIAL AND METHODS

Six domestic pigs received nine standardized defects at the calvaria, and an implant was inserted in the middle of each defect. The space between the implant and lateral bone portion was filled with MP pellets (n = 18) or MP supernatant (n = 18) or left unfilled (n = 18). After 14 and 28 days, three animals were sacrificed and specimens removed for further processing. Samples were microradiographically and histologically analysed. In addition, we immunohistochemically stained for anti-vWF as a marker of angiogenesis.

RESULTS

In the case of bone regeneration and vessel formation, the null hypothesis can be partially rejected. After 14 and 28 days, no significant difference was observed within groups regarding de novo bone formation, bone density and osseointegration. However, superior vessel formation was found at both time points.

CONCLUSION

Microparticles represent a promising treatment option to accelerate peri-implant vessel formation. Further studies are needed to investigate the regenerative properties of MPs more precisely.

Bone loss after ridge expansion with or without reflection of the periosteum

OBJECTIVE

To evaluate the role of the periosteum in preserving the buccal bone after ridge splitting and expansion with simultaneous implant placement.

MATERIAL AND METHODS

In 12 miniature pigs, the mandibular premolars and first molars were removed together with the interdental bone septa and the buccal bone. Three months later, ridge splitting and expansion of the buccal plate was performed with simultaneous placement of two titanium implants per quadrant. Access by a mucosal flap (MF) was prepared on test sides, while a mucoperiosteal flap (MPF) with complete denudation of the buccal bone was increased on control sides. After healing periods of six and 12 weeks, the animals were sacrificed for histologic and histometric evaluation.

RESULTS

In the MF group, all 16 implants were osseointegrated, while in the MPF group, four of 16 implants were lost. Noticeable differences of bone levels on the implant surface and of the bone crest (BC) were found between the MF and the MPF group. Buccally after 6 weeks, the median distance between the implant shoulder (IS) and the coronal-most bone on the implant (cBIC) was for the MF group -1.42 ± 0.42 mm and for the MPF group -4.80 ± 2.72 mm (P = 0.15). The median distance between the IS and the buccal BC was -1.24 ± 0.51 mm and -2.78 ± 1.98 mm (P = 0.12) for the MF and MPF group, respectively. After 12 weeks, median IS-cBIC was -2.12 ± 0.84 mm for MF and -7.19 mm for MPF, while IS-BC was -2.08 ± 0.79 mm for MF and -5.96 mm for MPF. After 6 weeks, the median buccal bone thickness for MF and MPF was 0.01 and 0 mm (P < 0.001) at IS, 1.48 ± 0.97 mm and 0 ± 0.77 mm (P = 0.07) at 2 mm apical to IS, and 2.12 ± 1.19 mm and 1.72 ± 01.50 mm (P = 0.86) at 4 mm apical to IS, respectively. After 12 weeks, buccal bone thickness in the MF group was 0 mm at IS, 0.21 mm at 2 mm apical to IS, and 2.56 mm at 4 mm apical to IS, whereas complete loss of buccal bone was measured from IS to 4 mm apical to IS for the MPF group.

CONCLUSIONS

In this ridge expansion model in miniature pigs, buccal bone volume was significantly better preserved when the periosteum remained attached to the bone.

Bone healing and the effect of implant surface topography on osteoconduction in hyperglycemia

Dental implant failures that occur clinically for unknown reasons could be related to undiagnosed hyperglycemia. The exact mechanisms that underlie such failures are not known, but there is a general consensus that bone growth is compromised in hyperglycemia. Nevertheless, contradictory findings exist related to peri-implant bone healing in hyperglycemia. We hypothesized that hyperglycemia delays early bone healing by impeding osteoconduction, and that the compromised implant integration due to hyperglycemia could be abrogated by using nanotopographically complex implants. Thus we undertook two parallel experiments, an osteotomy model and a bone in-growth chamber model. The osteotomy model tracked temporal bone healing in the femora of euglycemic and hyperglycemic rats using micro computed tomography (microCT) analysis and histology. The bone in-growth chamber model used implant surfaces of either micro- or nanotopographical complexity and measured bone-implant contact (BIC) using backscattered electron imaging in both metabolic groups. Quantitative microCT analyses on bone volume, trabeculae number and trabeculae connectivity density provided clear evidence that bone healing, both reparative trabecular bone formation and remodeling, was delayed in hyperglycemia, and the reparative bone volume changed with time between metabolic groups. Furthermore, fluorochrome labeling showed evidently less mineralized bone in hyperglycemic than euglycemic animals. An increased probability of osteoconduction was seen on nano-compared with microtopographically complex surfaces, independent of metabolic group. The nanotopographically complex surfaces in hyperglycemia outperformed microtopographically complex surfaces in euglycemic animals. In conclusion, the compromised implant integration in hyperglycemia is abrogated by the addition of nanotopographical features to an underlying microtopographically complex implant surface.

Early bone apposition to hydrophilic and hydrophobic titanium implant surfaces: a histologic and histomorphometric study in minipigs

OBJECTIVE

The first objective of this pilot study was to evaluate the impact of the hydrophilicity on the early phases of osseointegration. The second objective was to compare two hydrophilic implant surfaces with different geometries, surface roughness, and technologies achieving hydrophilicity.

MATERIAL AND METHODS

Twelve weeks after extraction, all four quadrants of nine minipigs received three dental implants, alternating between hydrophilic microrough surfaces (INICELL and SLActive) and a conventional hydrophobic microrough surface. After 5, 10, and 15 days of submerged healing, ground sections were prepared and subjected to histologic and histomorphometric analysis.

RESULTS

The histologic analysis revealed a similar healing pattern among the hydrophilic and hydrophobic implant surfaces, with extensive bone formation occurring between day 5 and day 10. With BIC values of greater than 50% after 10 days, all examined surfaces indicated favorable osseointegration at this very early point in healing. At day 15, the mean new bone-to-implant contact (newBIC) of one hydrophilic surface (INICELL; 55.8 ± 14.4%) was slightly greater than that of the hydrophobic microrough surface (40.6 ± 20.2%). At day 10 and day 15, an overall of 21% of the implants had to be excluded from analysis due to inflammations primarily caused by surgical complications.

CONCLUSION

Substantial bone apposition occurs between day 5 and day 10. The data suggest that the hydrophilic surface can provoke a slight tendency toward increased bone apposition in minipigs after 15 days. A direct comparison of two hydrophilic surfaces with varying geometries is of limited relevance.

Implants in bone: part II. Research on implant osseointegration: material testing, mechanical testing, imaging and histoanalytical methods

PURPOSE

In order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, it must undergo rigorous testing. To correctly interpret the results of studies on implant material osseointegration, it is necessary to have a sound understanding of all the testing methods. The aim of this overview is to elucidate the methods that are used for the experimental evaluation of the osseointegration of implant materials.

DISCUSSION

In recent decades, there has been a constant proliferation of new materials and surface modifications in the field of dental implants. This continuous development of innovative biomaterials requires a precise and detailed evaluation in terms of biocompatibility and implant healing before clinical use. The current gold standard is in vivo animal testing on well validated animal models. However, long-term outcome studies on patients have to follow to finally validate and show patient benefit.

CONCLUSION

No experimental set-up can provide answers for all possible research questions. However, a certain transferability of the results to humans might be possible if the experimental set-up is carefully chosen for the aspects and questions being investigated. To enhance the implant survival rate in the rising number of patients with chronic diseases which compromise wound healing and osseointegration, dental implant research on compromised animal models will further gain importance in future.