Bone-to-implant Contact Research Articles

Hard and soft tissue healing around implants with a modified implant neck configuration: An experimental in vivo preclinical investigation.

ObjectivesEvaluate the dimensions and morphology of peri‐implant tissues around a modified dental implant designed with tissue level connection and a convergent transmucosal neck, when compared with a conventional bone level implant connected to a cylindrical machined titanium abutment.Material and methodsEight experimental animals were used for this in vivo investigation, in whom 16 test and 16 control implants were placed following a random allocation sequence. The following histological outcomes at 4 and 12 weeks were evaluated: morphology of peri‐implant tissues, the soft tissue height and thickness, the horizontal and vertical bone remodeling, and the bone to implant contact (BIC).ResultsIn both early (4 weeks) and late (12 weeks) healing times, there were no statistically significant differences between test and control implants, with respect to the overall height and thickness of the peri‐implant hard and soft tissues. There was a tendency toward a more coronal free gingival margin (I‐FGM) at the buccal aspect of test when compared to control implants (at 4 weeks, difference of 0.97 mm (p = .572) and 0.30 mm (p = 1.000) at 12 weeks). Similarly, there was a tendency toward a more coronal position of the first bone to implant contact (I‐B) at the buccal aspect of test as compared to control implants (1.08 mm (p = 0.174) at 4 weeks and 0.83 mm (p = 0.724) at 12 weeks).ConclusionsHard and soft tissue healing occurred at both implant types with no statistically significant differences. Test implants tended to present a more coronal gingival margin (FGM) and first bone to implant contact (B).

Sustainable Surface Modification of Polyetheretherketone (PEEK) Implants by Hydroxyapatite/Silica Coating-An In Vivo Animal Study.

Polyetheretherketone (PEEK) has the potential to overcome some of the disadvantages of titanium interbody implants in anterior cervical and discectomy and fusion (ACDF). However, PEEK shows an inferior biological behavior regarding osseointegration and bioactivity. Therefore, the aim of the study was to create a bioactive surface coating on PEEK implants with a unique nanopore structure enabling the generation of a long-lasting interfacial composite layer between coating material and implant. Seventy-two PEEK implants—each thirty-six pure PEEK implants (PI) and thirty-six PEEK implants with a sprayed coating consisting of nanocrystalline hydroxyapatite (ncHA) embedded in a silica matrix and interfacial composite layer (SPI)—were inserted in the femoral condyles of adult rats using a split-side model. After 2, 4 and 8 weeks, the femur bones were harvested. Half of the femur bones were used in histological and histomorphometrical analyses. Additionally, pull-out tests were performed in the second half. Postoperative healing was uneventful for all animals, and no postoperative complications were observed. Considerable crestal and medullary bone remodeling could be found around all implants, with faster bone formation around the SPI and fewer regions with fibrous tissue barriers between implant and bone. Histomorphometrical analyses showed a higher bone to implant contact (BIC) in SPI after 4 and 8 weeks (p < 0.05). Pull-out tests revealed higher pull-out forces in SPI at all time points (p < 0.01). The presented findings demonstrate that a combination of a bioactive coating and the permanent chemical and structural modified interfacial composite layer can improve bone formation at the implant surface by creating a sustainable bone-implant interface. This might be a promising way to overcome the bioinert surface property of PEEK-based implants.

P2. Use of semaphorin 3A for improving osseointegration of titanium implants in type 2 diabetes mellitus rats

<h3>BACKGROUND CONTEXT</h3> Type 2 diabetes mellitus (T2DM) is a systemic disease that can compromise osseointegration of metal implants; thus, technologies that can improve osteogenesis in T2DM patients are needed. Semaphorin 3A (3A) is a novel osteoprotective protein that has been reported to improve bone formation. Our goal was to assess 3A for potential clinical use. However, current T2DM rat models lack translatability to human conditions. It is important to clarify osseointegration in a more translational T2DM. For this study, we used the Zucker diabetic Sprague Dawley rat (ZDSD) as a more clinically relevant T2DM model. It is a polygenic model with an intact leptin pathway as in humans, and exhibits human-like type 2 diabetes progression. <h3>PURPOSE</h3> This study used grit blasted/acid etched (SLA) Ti implants (microrough/hydrophobic) in ZDSD rat femurs to determine if 3A can improve their osseointegration in T2DM. <h3>METHODS</h3> Thirty male, 15-week-old ZDSD rats (D, Charles River) and 24 aged-matched male Sprague Dawley rats (N, Charles River) were used (IACUC approved). Rats were paired fed with a high-fat diet (Purina 5SCA) until 70% of D rats turned diabetic (blood glucose >250mg/dL for a week) and switched to a normal diet (Purina 5008) for the rest of the study. Three weeks after turning diabetic, D rats were randomized to three groups: click hydrogel delivery vehicle (D GEL), hydrogel containing 3A (D 3A+GEL), hydrogel implanted and 3A injected separately (D i3A+GEL) with n=7. N rats were randomized to N GEL, N 3A+GEL, N i3A+GEL with n=8. Holes were created bilaterally in the metaphysis of distal femurs, and hydrogels were inserted in the hole by mixing PEG-N3 and PEG-DBCO crosslinker with either 0.9% sterile saline in GEL and i3A+GEL or with 6ug 3A in 3A+GEL. SLA implants (Institut Straumann AG) were inserted immediately into the holes after GEL. i3A+GEL had bilateral subperiosteal 3A injections (6ug/leg) at implant sites on day 3 and day 10 post-surgery. Rats were euthanized at 4 weeks postop. Bone phenotype and osseointegration of isolated fixed femurs were assessed by micro-computed tomography (microCT). Total bone to implant contact (BIC) was defined as the percentage of the implant surface in contact with newly formed bone. Evaluations of BIC were also performed separately for two subregions, the medullary (bone marrow BIC) and the cortical compartment (cortical BIC). Removal torque testing was performed with fresh, non-fixed femurs. <h3>RESULTS</h3> D GEL had less trabecular bone formation than N GEL. Cortical bones at metaphysis and mid-diaphysis were not affected by T2DM. D GEL had less total BIC and less bone marrow BIC but no difference in cortical BIC than N GEL. D 3A+GEL had less total BIC and cortical BIC than N 3A+GEL but bone marrow BIC in D 3A+GEL was the same as in N 3A+GEL. Similar results were observed between D i3A+GEL and N i3A+GEL. Maximum torque and torsional stiffness were less in D GEL than N GEL but not different between D 3A+GEL and N 3A+GEL or D i3A+GEL and N i3A+GEL. There was no significant difference in torsional energy among all groups. <h3>CONCLUSIONS</h3> T2DM reduced trabecular bone formation but did not affect cortical bone. Osseointegration was impaired in T2DM indicated by having less total BIC. Sema3A improved osseointegration in T2DM indicated by increased bone marrow BIC and increased mechanical properties of integrated bone tissues after sema3A delivered by hydrogel or local injection. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Influence of osteoporosis and mechanical loading on bone around osseointegrated dental implants: A rodent study

This study aimed to evaluate the influence of estrogen deficiency and mechanical loading on bone around osseointegrated dental implants in a rat jaw model. The maxillary right first molars of 36 rats were extracted. One week later, the rats were divided into an unloaded group and a loaded group; short head implants and long head implants were inserted respectively. Nine weeks after implantation, the rats were further subjected to ovariectomy (OVX) or sham surgery. All animals were euthanized 21 weeks after OVX. Micro-computed tomography, histological and histomorphometrical evaluation were undertaken. Systemic bone mineral density and bone volume fraction decreased in OVX groups compared with the sham controls. Histomorphometrical observation indicated that unloaded OVX group showed significantly damaged osseointegration and bone loss versus the loaded OVX group. Both the bone density (BD) inside the peri-implant grooves and the percentage of bone-to-implant contact (BIC) were lower in the OVX groups than in the sham-surgery groups, although mechanical loading increased the BIC and BD in the loaded OVX group compared with the unloaded OVX group. An increased number of positive cells for tartrate-resistant acid phosphatase was observed in the OVX groups versus the sham controls. The percentage of sclerostin-positive osteocytes was lower under loaded compared with unloaded conditions in both the OVX groups and the sham controls. In conclusion, estrogen deficiency could be a risk factor for the long-term stability of osseointegrated implants, while mechanical loading could attenuate the negative influence of estrogen deficiency on bone formation and osseointegration.

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

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

Evaluation of zygomatic bone region for placement of quad zygomatic implants using CBCT in postmenopausal women

Insufficient height and width of the alveolar ridge at the implant site remains with inadequate bone volume following extraction in older age people especially in postmenopausal women. Postmenopausal women are susceptible to primary osteoporosis where more bone resorption than formation is seen resulting in decreased bone mass. Hence the present study aims to evaluate the zygomatic bone region for placement of quad zygomatic implants using CBCT.: A total of 120 CBCT images of female patients who were between the age group of 45 yrs to 65 yrs were taken. The zygomatic bone was evaluated for pneumatisation zones and thickness of zygomatic bone at three different regions i.e., superior, middle and inferior at nine points on zygoma bone along with bone to implant contact (BIC) region using virtual software. The largest thickness in the superior, middle and inferior regions were at Point A2(8.01+/-2.10 mm), Point B2 (7.01+/-1.62 mm), and Point C1 (6.65+/-1.64 mm), respectively. The virtually placed implants at Point A3 (15.92+/-4.16 mm) and Point B2 (12.02+/-3.62 mm) had the highest BICs. : To obtain the largest BICs, results suggested that the posterosuperior region (Point A3) and the centre of zygoma (Point B1) were the optimal places for the placement of quad zygomatic implants.

Early bone ingrowth and segmental stability of a trussed titanium cage versus a polyether ether ketone cage in an ovine lumbar interbody fusion model

BACKGROUND CONTEXTLumbar interbody fusion is an effective treatment for unstable spinal segments. However, the time needed to establish a solid bony interbody fusion between the two vertebrae may be longer than twelve months after surgery. During this time window, the instrumented spinal segment is assumed to be at increased risk for instability related complications such as cage migration or subsidence. It is hypothesized that the design of new interbody cages that enable direct osseointegration of the cage at the vertebral endplates, without requiring full bony fusion between the two vertebral endplates, might shorten the time window that the instrumented spinal segment is susceptible to failure. PURPOSETo quantify the bone ingrowth and resulting segmental stability during consolidation of lumbar interbody fusion using two different cage types. STUDY DESIGNPreclinical ovine model. METHODSSeven skeletally mature sheep underwent bi-segmental lumbar interbody fusion surgery with one conventional polyether ether ketone (PEEK) cage, and one newly developed trussed titanium (TT) cage. After a postoperative time period of 13 weeks, non–destructive range of motion testing, and histologic analysis was performed. Additionally, sample specific finite element (FE) analysis was performed to predict the stability of the interbody fusion region alone. RESULTSPhysiological movement of complete spinal motion segments did not reveal significant differences between the segments operated with PEEK and TT cages. The onset of creeping substitution within the cage seemed to be sooner for PEEK cages, which led to significantly higher bone volume over total volume (BV/TV) compared with the TT cages. TT cages showed significantly more direct bone to implant contact (BIC). Although the mean stability of the interbody fusion region alone was not statistically different between the PEEK and TT cages, the variation within the cage types illustrated an all-or-nothing response for the PEEK cages while a more gradual increase in stability was found for the TT cages. CONCLUSIONSSpinal segments operated with conventional PEEK cages were not different from those operated with newly developed TT cages in terms of segmental stability but did show a different mechanism of bone ingrowth and attachment. Based on the differences in development of bony fusion, we hypothesize that TT cages might facilitate increased early segmental stability by direct osseointegration of the cage at the vertebral endplates without requiring complete bony bridging through the cage. CLINICAL SIGNIFICANCEInterbody cage type affects the consolidation process of spinal interbody fusion. Whether different consolidation processes of spinal interbody fusion result in clinically significant differences requires further investigation.

Effect of Systemic Calcitonin Delivery with and Without Adjunct Local Platelet-rich Fibrin Therapy on Osseointegration in Ovariectomized Osteoporotic Rabbits: A Scanning Electron Microscopy-based Study.

It is hypothesised that systemic calcitonin delivery with adjunct local platelet-rich fibrin (PRF) therapy is more effective in augmenting osseointegration than calcitonin delivery alone under experimental osteoporosis conditions. The primary objective of the present experiment was to assess the effect of systemic calcitonin delivery with and without adjunct local PRF therapy on osseointegration in ovariectomised osteoporotic rabbits. Thirty female bilaterally ovariectomized rabbits were used. The animals were fed a low-calcium diet to establish a model for osteoporosis. In each animal, 2 implants were bilaterally placed in tibia. The animals were randomly divided equally into 3 groups. In group 1, no treatment was offered (control group). In groups 2 and 3, the animals received intramuscular injections of calcitonin without and with local PRF delivery prior to implant placement, respectively. All animals were euthanised at 12 weeks, and osseointegration was assessed as the gap widths between the bone and implant surface in the cervical, middle and apical third using scanning electron microscopy and energy-dispersive x-ray spectroscopy. The bone-to-implant contact (BIC) was also measured. p < 0.05 was defined as statistically significant. Gap widths in the cervical (p < 0.001), middle (p < 0.001) and apical third (p < 0.001) were statistically significantly higher in group 1 than groups 2 and 3. Gap widths in the cervical (p < 0.001), middle (p < 0.001) and apical third (p < 0.001) were significantly higher in group 3 than group 2. The mean BIC was statistically significantly higher in the cervical (p < 0.001), middle (p < 0.001) and apical third (p < 0.001) in group 3 compared with groups 2 and 3. When used as an adjunct to calcitonin, PRF enhanced osseointegration in an experimental osteoporosis model. However, further well-designed studies with inclusion of additional groups (treatment with PRF alone) are needed.

Effects of Autologous Bone Marrow Mesenchymal Stem Cells and Platelet-Rich Plasma on Bone Regeneration and Osseointegration of a Hydroxyapatite-Coated Titanium Implant

Bone regeneration remains one of the major clinical needs in orthopedics, and advanced and alternative strategies involving bone substitutes, cells, and growth factors (GFs) are mandatory. The purpose of this study was to evaluate whether the association of autologous bone marrow mesenchymal stem cells (BMSC), isolated by ‘one-step surgical procedure’, and activated platelet rich plasma (PRP) improves osseointegration and bone formation of a hydroxyapatite-coated titanium (Ti-HA) implant, already in clinical use, in a rabbit cancellous defect. The GFs present in plasma, in inactivated and activated PRP were also tested. At 2 weeks, histology and histomorphometry highlighted increased bone-to-implant contact (BIC) in Ti-HA combined with BMSC and PRP in comparison to Ti-HA alone and Ti-HA + PRP. The combined effect of BMSC and PRP peaked at 4 weeks where the BIC value was higher than all other treatments. At both experimental times, newly formed bone (Trabecular Bone Volume, BV/TV) in all tested treatments showed increased values in comparison to Ti-HA alone. At 4 weeks Ti-HA + PRP + BMSC showed the highest BV/TV and the highest osteoblasts number; additionally, a higher osteoid surface and bone formation rate were found in Ti-HA + BMSC + PRP than in all other treatments. Finally, the analyses of GFs revealed higher values in the activated PRP in comparison to plasma and to non-activated PRP. The study suggests that the combination of autologous activated PRP, as a carrier for BMSCs, is a promising regenerative strategy for bone formation, osseointegration, and mineralization of bone implants.

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

ObjectiveHealing of soft tissues and improvement of aesthetics have become major research objectives in implantology and renewed the interest for ceramics implants. The aim of this study was to evaluate the pre-clinical performance of screw-shaped sandblasted-etched implants processed from an innovative zirconia-based ceramic composite, in comparison to titanium. MethodsTwenty-four ceramic and twenty-four titanium screw-shaped sandblasted-etched dental implants were tested in a split-mouth design in six Beagle dogs. Surface topographies were investigated by confocal microscopy. Local tissue effects were evaluated at 4 and 13 weeks after implantation through histology. An ANOVA statistical analysis (5% risk; p < 0.05) was performed to compare peri-implant quantitative histomorphometric parameters on buccal and lingual sides, including Bone to Implant Contact (BIC) among test groups and time-periods. ResultsTitanium and ceramic implants presented respectively moderate and minimal roughness. After 4 and 13 weeks, ceramic implants showed an inflammatory tissue response close to titanium implants. At both period of time there was no significant difference between the titanium and ceramic groups in terms of BIC values (mean ± SD) at the lingual or buccal sides or when combining buccal + lingual BIC values (respectively for titanium and ceramic, 68.4 ± 14.7 % and 75.0 ± 13.5 % at 4 weeks, and 92.0 ± 8.6 % and 86.1 ± 13.8 % at 13 weeks). SignificanceWithin the limits of the present study, it can be concluded that newly developed zirconia-based ceramic composite dental implants have similar biocompatibility and osseointegration to those observed in titanium implants. These pre-clinical results corroborate the potential for the use of these new zirconia-based ceramics in oral implantology.

Improvement of Osseointegration by Ultraviolet and/or Simvastatin Treatment on Titanium Implants with or without Bone Graft Materials.

We evaluated and compared ultraviolet (UV) treatment and simvastatin (SIM) immersion effects on the osseointegration of sandblasted, large-grit, acid-etched (SLA) titanium dental implants at two different time points in rabbit tibias, with or without xenogenic bone graft materials. The surface alteration on simvastatin treatment titanium discs was analyzed using an infrared spectrometer. Implants were categorized into four groups according to the surface treatment type. Twelve rabbits received two implants per tibia. A tibial defect model was created using a trephine bur, with implants in contact with the bone surface and bovine bone graft materials for gap filling. The rabbits were sacrificed after 2 or 4 weeks. UV treatment or SIM immersion increased the bone-to-implant contact (BIC) on nongrafted sides, and both increased the BIC and bone area (BA) on grafted sides. The application of both treatments did not result in higher BIC or BA than a single treatment. At two different time points, BIC in the nongrafted sides did not differ significantly among the UV and/or SIM treated groups, whereas BA differed significantly. UV or SIM treatment of SLA titanium implants accelerates osseointegration in tibias with or without xenogenic bone graft materials. The combination of both treatments did not show synergy.

Analysis In Vivo of Bone Modulation in Hydrophilic and Hydrophobic Titanium Implant Surfaces.

To evaluate whether a hydrophilic surface treatment compared with a hydrophobic implant surface can enhance osseointegration by analysis of calcium deposition, bone-to-implant contact (BIC), bone volume (BV), and upregulation of genes involved in bone formation. Sixty implants (n = 60) with a hydrophobic (SAE) or hydrophilic (SAE-HD) surface treatment were placed bilaterally in each femur of 3-month-old male mice (n = 30). Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) were utilized for quantifying the presence of calcium on the implant surface 7 days after implant placement. The specimens were analyzed after 14 and 21 days for BIC and BV by Nano CT scanning followed by histologic evaluation. Additionally, 1, 3, and 7 days postsurgery, femurs were harvested, implants were explanted, and gene expression (Sp7, Bsp, Sost, IL-1α, and IL-10) by quantitative real-time polymerase chain reaction was studied. Moreover, implants were characterized for surface roughness area. Data were statistically analyzed with two-way analysis of variance (ANOVA) followed by the Tukey test (P < .05). The amount of calcium on the surface was higher for SAE-HD after 7 days. Nano CT revealed significantly more BV in the SAE-HD than the SAE surface. The histologic assessment showed increased BIC in SAE-HD in comparison to SAE. SAEHD showed significantly increased levels of genes involved in bone formation. Both surfaces were able to modulate bone responses toward osteoblast differentiation. SAE-HD presented a better response compared with SAE.

Simvastatin reverses the harmful effects of high fat diet on titanium rod osseointegration in ovariectomized rats.

The objectives of the present study were to determine whether simvastatin (SIM) could reverse the harmful effects on titanium rod osseointegration in ovariectomized rats fed high-fat diet (HFD). Ovariectomized female Sprague-Dawley rats were randomly allocated to three groups and received SIM treatment plus HFD for 12 weeks. We then evaluated the microstructure parameters, histological parameters, biomechanical parameters, bone turnover, and blood lipid level. After 12 weeks of treatment, SIM can significantly improve bone formation around the titanium rod and osseointegration including higher values of maximum push-out force, bone area ratio (BAR), bone-to-implant contact (BIC), bone mineral density (BMD), bone volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), mean connective density (Conn.D) when compared with the HFD group. In addition, system administration of SIM showed positive effects on collagen type 1 cross-linked C-telopeptide (CTX-1), procollagen I N-terminal propeptide (PINP), total cholesterol (TC), triglycerides (TGL), low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol. Compared with the HFD group, lower values of CTX-1, P1NP, TC, TGL and LDL were observed in the SIM+HFD group (P < 0.05). Our findings revealed that HFD may have an adverse effect on osseointegration in osteoporotic conditions, and the harmful effect of HFD on osseointegration could be reversed by SIM.

Bone healing around titanium implants in a preclinical model of bile duct ligation-induced liver injury.

ObjectivesChronic liver disease increases the risk for periodontal disease and osteoporotic fractures, but its impacts on bone regeneration remain unknown. Herein, we studied the impact of liver cirrhosis on peri‐implant bone formation.Material and MethodsA total of 20 male Wistar rats were randomly divided into two groups: one with the common bile duct ligated (BDL) and the respective sham‐treated control group (SHAM). After four weeks of disease induction, titanium mini‐screws were inserted into the tibia. Successful induction of liver cirrhosis was confirmed by the presence of clinical symptoms. Another four weeks later, peri‐implant bone volume per tissue volume (BV/TV) and bone‐to‐implant contact (BIC) were determined by histomorphometric analysis.ResultsPeri‐implant bone formation was not significantly different between the SHAM and BDL groups. In the cortical compartment, the median percentage of peri‐implant new bone was 10.1% (95% CI of mean 4.0–35.7) and 22.5% (13.8–30.6) in the SHAM and BDL groups, respectively (p = .26). Consistently, the new bone in direct contact with the implant was 18.1% (0.4–37.8) and 23.3% (9.2–32.8) in SHAM and BDL groups, respectively (p = .38). When measuring the medullary compartment, the new bone area was 7.1% (4.8–10.4) and 10.4% (7.2–13.5) in the SHAM and BDL groups, respectively (p = .17). Medullary new bone in direct contact with the implant was 10.0% (1.2–50.4) and 20.6% (16.8–35.3) in SHAM and BDL groups, respectively, and thus comparable between the two groups (p = .46).ConclusionsBile duct ligation has no significant impact on the early stages of peri‐implant bone formation.

Innovative implant design for continuous implant stability: A mechanical and histological experimental study in the iliac crest of goats

Objectivesthis in vivo study reports on mechanical torque data as well as the biological evaluation up to 6 weeks after placement of implants with a unique wide knife thread design in a goat iliac crest model. We hypothesized that implants with this thread design would show substantial primary stability at a continuous level toward secondary stability. Methods64 MegaGen Anyridge® implants were used with diameters 3.5 mm, 4.0 mm, 5.0 mm and 6.0 mm (n = 8). Implants were placed monocortically in the iliac crest of 16 healthy female Saanen goats, both on the right (for torque measurements) and left side (for histology/-morphometry). Torque-in at implant installation and torque-out at 2 and 6 weeks of implantation was measured, as well as bone-to-implant contact (BIC) and bone-area between the screw threads (BA). ResultsHistology showed intimate bone-to-implant contact with a maturating trabecular structure between 2 and 6 weeks. Torque values showed a dependency on implant diameter. For all implant diameters, torque-in values were similar to torque-out values at 2 weeks. At 6 weeks however, all torque-out values were significantly increased. BIC and BA percentages showed similar values for all diameters at both 2 and 6 weeks. ConclusionsThese results prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants in the goat iliac crest model. The increased torque-out values at 6 weeks without increasing BIC and BA percentages correlate with the observed maturation of bone-to-implant contact quality over time. Clinical significanceIt is a challenge to optimize implants with continuous primary stability and rapid transition into secondary stability to minimize the duration of the lag-phase. The results of this study prove the absence of a lag-phase in implant stability for MegaGen Anyridge® implants. Consequently, the data from this work are important for the treatment of individual patients ‘translating’ these findings into clinical implant procedures.

Effects of Gamma Radiation-Induced Crosslinking of Collagen Type I Coated Dental Titanium Implants on Osseointegration and Bone Regeneration.

This study aimed to compare two methods of crosslinking collagen type I on implanted titanium surfaces, that is, using glutaraldehyde (GA) or gamma-rays (GRs), in a beagle dog model. For in vivo experiments, implants were allocated to three groups and applied to mandibular bone defects in beagle dogs; Group SLA; non-treated Sandblasted, large grit, acid-etched (SLA) implants, Group GA; SLA implants coated with GA crosslinked collagen type I, Group GR; SLA surface implants coated with collagen type I and crosslinked using 25 kGy of 60Co gamma radiation. New bone μCT volumes were obtained, and histologic and histometric analyses were performed in regions of interest. The GR group had significantly better new bone areas (NBAs) and bone to implant contact (BIC) results than the SLA group (p < 0.05), but the GA and GR groups were similar in this respect. New bone volumes and inter-thread bone densities (ITBD) were non-significantly different in the three groups (p > 0.05). Within the limits of this study, gamma-ray collagen crosslinking on titanium implants can be considered a substitute for glutaraldehyde crosslinking.

Systematic Review and Meta-Analysis of the Effectiveness of Calcium-Phosphate Coating on the Osseointegration of Titanium Implants.

Ca-P coatings on Ti implants have demonstrated good osseointegration capability due to their similarity to bone mineral matter. Three databases (PubMed, Embase, and Web of Science) were searched electronically in February 2021 for preclinical studies in unmodified experimental animals, with at least four weeks of follow-up, measuring bone-to-implant contact (BIC). Although 107 studies were found in the initial search, only eight experimental preclinical studies were included. Adverse events were selected by two independent investigators. The risk of bias assessment of the selected studies was evaluated using the Cochrane Collaboration Tool. Finally, a meta-analysis of the results found no statistical significance between implants coated with Ca-P and implants with etched conventional surfaces (difference of means, random effects: 5.40; 99% CI: −5.85, 16.65). With the limitations of the present review, Ca-P-coated Ti surfaces have similar osseointegration performance to conventional etched surfaces. Future well-designed studies with large samples are required to confirm our findings.

The Effect of Coronal Implant Design and Drilling Protocol on Bone-to-Implant Contact: A 3-Month Study in the Minipig Calvarium.

Background: Stress concentrated at an implant’s neck may affect bone-to-implant contact (BIC). The objective of this study was to evaluate four different implant neck designs using two different drilling protocols on the BIC. Methods: Ninety-six implants were inserted in 12 minipigs calvarium. Implants neck designs evaluated were: type 1–6 coronal flutes (CFs), 8 shallow microthreads (SMs); type 2–6 CFs,4 deep microthreads (DMs); type 3–4 DMs; type 4–2 CFs, 8 SMs. Two groups of forty-eight implants were inserted with a final drill diameter of 2.8 mm (DP1) or 3.2 mm (DP2). Animals were sacrificed after 1 and 3 months, total-BIC (t-BIC) and coronal-BIC (c-BIC) were evaluated by nondecalcified histomorphometry analysis. Results: At 1 month, t-BIC ranged from 85–91% without significant differences between implant types or drilling protocol. Flutes on the coronal aspect impaired the BIC at 3 m. c-BIC of implant types with 6 CFs was similar and significantly lower than that of implant types 3 and 4. c-BIC of implant type 4 with SMs was highest of all implant types after both healing periods. Conclusions: BIC was not affected by the drilling protocol. CFs significantly impaired the -BIC. Multiple SMs were associated with greater c-BIC.

Osseointegration of a novel 3D porous Ti-6Al-4V implant material - Histomorphometric analysis in rabbits.

Porous structure properties are known to conduct initial and long-term stability of titanium alloy implants. This study aims to assess the histomorphometric effect of a 3-D porosity in Ti-6Al-4V implants (PI) on osseointegration in comparison to solid Ti-6Al-4V implants (SI). The PI was produced in a spaceholder method and sintering and has a pore size of mean 400 µm (50 µm to 500 µm) and mimics human trabecular bone. Pairs of PI and equal sized SI as reference were bilaterally implanted at random in the lateral femoral condyle of 16 Chinchilla-Bastard rabbits. The animals were sacrificed after 4 and 12 weeks for histomorphometric analysis. The histomorphometric evaluation confirmed a successful short-term osseohealing (4 weeks) and mid-term osseoremodeling (12 weeks) for both types of implants. The total newly formed bone area was larger for PI than for SI after 4 and 12 weeks, with the intraporous bone area being accountable for the significant difference (p<0.05). A more detailed observation of bone area distribution revealed a bony accumulation in a radius of +/- 500 µm around the implant surface after remodeling. The bone-to-implant contact (BIC) increased significantly (p<0.05) from 4 to 12 weeks (PI 26.23 % to 42.68 %; SI 28.44 % to 47.47 %) for both types of implants. Due to different surface properties, however, PI had a significant (p<0.05) larger absolute osseous contact (mm) to the implant circumference compared to the SI (4 weeks: 7.46 mm vs 5.72 mm; 12 weeks: 11.57 mm vs 9.52 mm [PI vs. SI]). The regional influences (trabecular vs. cortical) on bone formation and the intraporous distribution were also presented. Conclusively, the porous structure and surface properties of PI enable a successful and regular osseointegration and enhance the bony fixation compared to solid implants under experimental conditions.

Peri-implant bone preservation of a novel, self-cutting, and fully tapered implant in the healed crestal ridge of minipigs: submerged vs. transgingival healing

ObjectivesThe aim of this study was to assess the influence of transgingival compared with submerged healing on peri-implant bone maintenance around a novel, fully tapered implant in a healed crestal ridge in minipigs.Materials and methodsIn each of 12 minipigs, two implants (Straumann® BLX, Roxolid® SLActive®, Ø 3.75 × 8 mm) were placed. Implants were either left for submerged or for transgingival healing for 12 weeks. Measurements performed were bone-to-implant contact (BIC), first bone-to-implant contact (fBIC), bone area to total area (BATA), perpendicular bone crest to implant shoulder (pCIS), bone height change from placement, and bone overgrowth (for submerged implants).ResultsNo significant differences were found between transgingival and submerged healing in any of the measured parameters, except for BATA on the buccal aspect in which significantly more bone formation was found for the transgingival healing group. For both groups, there was a gain in crestal bone height during the 12-week healing period.ConclusionsLoaded compared with unloaded implants displayed comparable levels of osseointegration and equivalent marginal bone levels. This qualifies the implant placement protocol with respect to the osteotomy dimensions and subcrestal placement protocol for immediate loading.Clinical relevanceThe here presented results related to osseointegration and crestal bone maintenance after submerged or transgingival healing have demonstrated a high level of consistency in the used in vivo translational model. The obtained results support the translation of the novel implant type in conjunction with the developed surgical workflow and placement protocol into further clinical investigation and use.