Bone-to-implant Contact Research Articles

Rapid Establishment and Validation of an Experimental Model of Osteoporosis for Implant-Bone Analysis.

Osteoporosis is an increasingly prevalent disease. The development of an osteoporosis-like experimental animal model is of great importance for the study of peri-implant osteogenesis in osteoporosis. The present authors aimed to establish a rapid modeling method of osteoporotic rabbits for implant-bone analysis and validate whether the models can affect the implant osseointegration. The present study included 29 female New Zealand rabbits (age: 5 to 6 months). Two rabbits were lost during anesthetization. Of the remaining 27 rabbits, 18 received an ovariectomy, with 9 receiving dexamethasone injections for 8 weeks (OVX+D group) and 9 receiving equivalent-volume saline injections (OVX group). As a control group, the remaining 9 rabbits were sham-operated and received an equivalent volume of normal saline (SHAM group). Then, serum biochemical markers of bone metabolism were detected and densitometric measurements were performed. Implants were then placed in the tibias of each rabbit. Bone samples (including implants) were obtained after 4, 8, and 12 weeks of healing and were subjected to histologic and histomorphometric analyses. The results showed that the OVX+D group experienced a 32% reduction in bone mineral density (BMD) from baseline. The BMD of the OVX+D group was significantly lower than that of the SHAM and OVX groups. Moreover, alkaline phosphatase (ALP) blood concentrations of in the OVX+D group were increased significantly. The osteoporotic rabbits exhibited marked decreases in osseointegration, characterized by slowed bone formation and decreased bone-to-implant contact (BIC). The combination of an ovariectomy and dexamethasone injections could experimentally induce osteoporosis in rabbits in the short term, which can be used as an appropriate animal model to study the osseointegration of implants under osteoporosis.

Performance of a new implant system and drilling protocol-A minipig intraoral dental implant model study.

A new implant system encompassing implants with a tri-oval cross-sectional design and a simplified site preparation protocol at low speed and no irrigation has been developed. The objective of this study was to assess the safety and efficacy of the new implant system using the minipig intraoral dental implant model. Eight Yucatan minipigs were included. Twelve weeks after extractions, four implants per animal were randomly placed and allowed to heal transmucosal for 13 weeks: two Ø3.5 × 10 mm implants with a back-tapered collar and circular cross-section (control) and two Ø3.5 × 11 mm implants with tri-oval collar and cross-section (test). MicroCT and histological analysis was performed. Thirty-two implants were placed; one implant for the control group was lost. Histologically, BIC was higher in the test compared with the control group (74.1% vs. 60.9%, p < .001). At the platform level, inflammation was statistically significantly higher albeit mild in the test compared with the control group. No other significant differences were observed between groups. MicroCT analysis showed that bone-to-implant-contact (BIC) and trabecular thickness were statistically significantly higher for the test than the control group. Test group had significantly higher first BIC distance than controls on lingual sites. The present study results support the safety and efficacy of the new dental implant system and simplified site preparation protocol; human studies should be carried out to confirm these findings.

Gas Plasma Treatment Improves Titanium Dental Implant Osseointegration-A Preclinical In Vivo Experimental Study.

Recent technological advancements led to the development of various plasma-based technologies for post-packaging modifications. The purpose of the present preclinical in vivo study was to assess the safety and efficacy of a novel chairside nonthermal gas plasma treatment for enhancing osseointegration of titanium implants. Six male mixed foxhounds underwent extraction of mandibular premolars and first molars, and the sockets healed for 42 days. Canine mandibles were randomized to receive either plasma-treated (test) or non-plasma-treated (control) dental implants. A total of 36 implants were placed in six animals, and they were sacrificed at 2 weeks (two animals), 4 weeks (two animals), and 6 weeks (two animals) after the implant surgery. When the radiographic analysis was performed, the changes in bone level were not statistically significant between the two groups at 2 weeks and 4 weeks. The difference became significant at 6 weeks (p = 0.016), indicating more bone loss from baseline to 6 weeks for the control group. The bone-to-implant contact (BIC) appeared to be higher for the test groups at all time points, and the BIC was significantly higher for the test group at 4 weeks (p = 0.046). In conclusion, this study underscored the potential of nonthermal plasma treatment in enhancing implant osseointegration.

Effect of polydeoxyribonucleotide on early bone formation in lateral bone augmentation with immediate implant placement: an experimental in vivo study

This study investigated early bone formation using collagenated biphasic calcium phosphate (CBCP) with or without polynucleotide (PDRN). Third (P3) or fourth (P4) premolars of six male beagle dogs were extracted and 5-mm-high dehiscence defects were created, followed by 3D-printed implant placement. The buccal bone defects were grafted with (i) CBCP and collagen membrane or (ii) CBCP soaked in polydeoxyribonucleotide (CBCP/PDRN) and collagen membrane. Samples of the experimental sites were harvested at 2- and 6-weeks post-surgery. The specimens were evaluated with radiologic and histomorphometric analysis. No significant differences were found between the CBCP and CBCP/PDRN groups in the micro-CT analysis at 2 or 6 weeks. No significant differences were observed in bone-to-implant contact (BIC) or bone area fraction occupancy (BAFO) in buccal augmented and lingual non-augmented areas. In the qualitative analysis, the new bone (NB) area and NB proportion in buccal augmented areas showed significantly higher values in the CBCP/PDRN group than in the CBCP group at 2 and 6 weeks. Peri-implant buccal dehiscence defects with immediate 3D-printed implant placement were corrected using a collagen membrane and CBCP or CBCP/PDRN. PDRN might have the potential to facilitate early bone formation with sufficient stability over time in dehiscence defects.

Three-dimensional radiographic assessment of immediate implant placement in the posterior mandible: A novel parameter-based classification

ObjectivesTo assess the implant position (IP), the interradicular septum width (ISW) and radiographic bone to implant contact (BIC), when simulating an immediate implant placement in first and second mandibular molars. Study Design75 patients (150 sites) were studied using cone beam computed tomography scans (CBCT) and computer aided design software. Implants were placed in a prosthetically driven position; subsequently, IP and BIC were digitally calculated. Linear ISW was also analyzed at 2, 4 and 6mm apically to the highest septal bony peak.Multiple linear regressions were performed to assess relationships between BIC and the different predictive variables. Additionally, the receiver operating characteristics (ROC) curve was used to create a model for BIC based on the ISW at 2mm. ResultsBIC in implants replacing first molars was the highest at the septal (S) position when compared to those in septal-mesial (S–M) position (p-value 0.001). As for the second molar, the highest percentage of BIC was recorded at the septal (S) position, followed by those in S–M and mesial (M) positions (p<0.001). ConclusionAccording to the proposed classification, clinician must consider the ISW and IP when placing immediate implant in the first and second mandibular molar sites. When tackling first molars, S position is predominant, while S–M position is the most common in the second molars. ISW at 2mm should be at least respectively 2mm and 2.5mm at the first and second molar sites to achieve 50% of BIC.

Comparison of osteogenesis and osseointegration following implant placement with simultaneous maxillary sinus augmentation using particulate and collagenated block types of deproteinized porcine bone mineral: a radiographic and histomorphometric analysis.

This study aimed to compare osseointegration and osteogenesis after single-stage maxillary sinus augmentation with the lateral window using particulate deproteinized porcine bone mineral (PDPBM) and collagenated block deproteinized porcine bone mineral (BDPBM). Bi-maxillary premolars of six beagle dogs were extracted. Eight weeks later, an implant was placed into each augmented sinus with PDPBM or BDPBM according to a split-mouth design. Eight weeks later, all specimens were harvested. Each specimen was separated into the region of interest with the implant (ROI-I) and region of interest with sinus augmented area (ROI-S) 5mm away from ROI-I. ROI-I and ROI-S were evaluated through micro-computed tomography and histomorphometry. Bone substitute insertion took longer for the PDPBM group than for the BDPBM group (P = 0.002). In ROI-I, three-dimensional bone-to-implant contact (BIC) did not show statistically significant differences between the groups. Two-dimensional BIC also showed comparable values for both groups. In ROI-S, the graft material volume/tissue volume, trabecular bone pattern factor, and structural model index were higher in the BDPBM group than in the PDPBM group (P < 0.05). The proportions of new bone, graft material, and connective tissue were not significantly statistically different between groups. Less new bone was found in the apical area than in the coronal or middle areas in the BCPBM group (P < 0.05). BDPBM may save time in inserting bone substitutes and provide comparable osteogenesis and osseointegration to PDPBM. When performing sinus augmentation, BDPBM might improve operator's convenience with comparable biological results compared to PDPBM.

Comparison between bone–implant interfaces of microtopographically modified zirconia and titanium implants

The aim of this study was to investigate the surface characteristics and evaluate the bone–implant interfaces of injection molded zirconia implants with or without surface treatment and compare them with those of conventional titanium implants. Four different zirconia and titanium implant groups (n = 14 for each group) were prepared: injection-molded zirconia implants without surface treatment (IM ZrO2); injection-molded zirconia implants with surface treatment via sandblasting (IM ZrO2-S); turned titanium implants (Ti-turned); and titanium implants with surface treatments via sandblasting with large-grit particles and acid-etching (Ti-SLA). Scanning electron microscopy, confocal laser scanning microscopy, and energy dispersive spectroscopy were used to assess the surface characteristics of the implant specimens. Eight rabbits were used, and four implants from each group were placed into the tibiae of each rabbit. Bone-to-implant contact (BIC) and bone area (BA) were measured to evaluate the bone response after 10-day and 28-day healing periods. One-way analysis of variance with Tukey’s pairwise comparison was used to find any significant differences. The significance level was set at α = 0.05. Surface physical analysis showed that Ti-SLA had the highest surface roughness, followed by IM ZrO2-S, IM ZrO2, and Ti-turned. There were no statistically significant differences (p > 0.05) in BIC and BA among the different groups according to the histomorphometric analysis. This study suggests that injection-molded zirconia implants are reliable and predictable alternatives to titanium implants for future clinical applications.

Osseointegration of Tantalum Trabecular Metal in Titanium Dental Implants: Histological and Micro-CT Study.

This study aimed to investigate the impact of the Tantalum Trabecular Metal dental implant design on implant stability and the process of osseointegration following its placement in the rabbit femoral condyle. The subjects for the experiment consisted of 10 New Zealand white rabbits. Twenty implants, comprising 10 Trabecular Metal (TM) and 10 Traditional Screw Vent (TSV) implants, were placed into the femoral condyles of these rabbits. The implant type was alternated based on a random sequence. Following a healing period of 8 weeks, the implants were retrieved for further analysis using micro-computed tomography (micro-CT), histological studies, and histomorphometry evaluations. The Bone-to-Implant Contact (BIC) ratio and the Bone Volume (BV) percentage in the region of interest were subsequently assessed. The BIC and BV values between TM and TSV implants were compared using the Student t-test. The TM implants exhibited significantly greater BIC and BV scores. In particular, the BIC percentage was recorded as 57.9 ± 6.5 for the TM implants, as opposed to 47.6 ± 8 for the TSV implants. Correspondingly, the BV percentage was 57 ± 7.3 for the TM implants and 46.4 ± 7.4 for the TSV implants. The bone volume percentage measured using micro-CT evaluation was 89.1 ± 8.7 for the TM implants and 79.1 ± 8.6 for the TSV implants. Given the observed results, it is plausible to suggest that the bone growth surrounding the tantalum mesh could have improved the integration of the bone and facilitated its ingrowth into the TM implant.

Effects of Implant Diameter on Implant Stability and Osseointegration in the Early Stage in a Dog Model.

Purpose: To determine the optimal implant diameter under limited bone width by comparing the effects of implants with different diameters on implant stability, peri-implant bone stability, and osseointegration. In addition, to evaluate the reliability of resonance frequency analysis (RFA) in detecting osseointegration and marginal bone level (MBL). Materials and Methods: Mandibular premolars and first molars of seven beagle dogs were extracted. After 8 weeks, their mandibular models and radiographic information were collected to fabricate implant templates. Implant sites were randomly divided into three groups according to diameter: Ø3.3, Ø4.1, and Ø4.8 mm. Implant stability quotient (ISQ) measurement and radiographic evaluation were performed after surgery (baseline) and at 4, 8, and 12 weeks. Three dogs were euthanized at 4 weeks to observe osteogenesis and implant-tissue interface biology. Four dogs were euthanized at 12 weeks to observe osseointegration. Hard tissue sections were prepared to analyze osteogenesis (fluorescence double labeling) and osseointegration (methylene blue-acid fuchsin staining). Results: At baseline and at 4, 8, and 12 weeks, the ISQ values of Ø4.1- and Ø4.8-mm implants did not differ (P > .05), but both had higher values than the Ø3.3-mm implants (P < .05). The mean marginal bone resorption (MBR) associated with Ø3.3-, Ø4.1-, and Ø4.8-mm implants was 0.65 ± 0.58 mm, 0.37 ± 0.28 mm, and 0.73 ± 0.37 mm, respectively. The buccal MBR of Ø4.8-mm implants was significantly higher than that of Ø4.1-mm implants (P < .05). The bone-to-implant contact (BIC) percentage at 12 weeks did not differ for any group (P > .05). The correlation coefficients between the ISQ and MBL of the Ø3.3-, Ø4.1-, and Ø4.8-mm implants were -0.84 (P < .01), -0.90 (P < .001), and -0.93 (P < .001), respectively, while that between the ISQ and BIC was 0.15 (P > .05). Conclusions: During the early healing stage, the performance of Ø4.1- and Ø4.8-mm implants in terms of implant stability was better than that of Ø3.3-mm implants. Implant diameter may not influence BIC percentage. RFA can be used to evaluate implant stability and MBL but is not suitable to assess the degree of osseointegration.

Effect of Drilling Preparation on Immediately Loaded Implants: An In Vivo Study in Sheep.

To determine the biologic and biomechanical effects of two implant drilling protocols on the cortical bone around implants subjected to immediate loading. A total of 48 implants were inserted into the mandibles of six sheep following one of two drilling protocols: undersized preparation (US; n = 24) and nonundersized preparation (NUS; n = 24). Immediately after implant insertion, an abutment was placed on each implant and 36 implants were subjected to 10 sessions of dynamic vertical loads (1,500 cycles, 1 Hz) of 25 N or 50 N. Insertion torque value (ITV) was recorded at implant installation. Resonance frequency analysis (RFA) was measured at implant insertion and at each loading session. Fluorochrome was administered at day 17, and the animals were euthanized after 5 weeks. The removal torque values (RTVs) were measured, and samples underwent histomorphometric, μCT (microcomputed tomography), and fluorescence image acquisition analyses. The bone volume density (BV/TV), bone-to-implant contact (BIC), bone area fraction occupancy (BAFO), and fluorochrome stained bone surface (MS) were calculated. A linear mixed model analysis was performed, and Pearson paired correlation was calculated. Five implants from the NUS group failed, with a mean ITV of 8.8 Ncm and an RFA value of 57. The mean ITVs for US group and NUS group were 80.5 (± 14) Ncm and 45.9 (± 25) Ncm, respectively (P < .001). No differences were noted in the RFA values from the time of implant insertion until the end of the study. No differences in RTV, BV/TV, BAFO, or MS were observed between the groups. Intense new bone formation took place in the NUS group implants that were subjected to load. Undersized preparation of cortical bone ensured a greater BIC compared to a nonundersized preparation. Moreover, this study demonstrated that immediate loading did not interfere with the osseointegration process, but loading induced intense new bone formation in the NUS group. It is not recommended to immediately load the implants when the clinically perceived primary stability is lower than an ITV of 10 Ncm and an RFA value of 60. Int J Oral Maxillofac Implants 2023;38:607-618. doi: 10.11607/jomi.9949.

Biomechanical and Histologic Evaluation of Osseointegration of Titanium Dental Implants Modified by Various Combinations of Sandblasting, Acid-Etching, Hydroxyapatite, and Hyaluronic Acid Coating Techniques.

To compare the osseointegration process of the titanium dental implants with five different surface characteristics-sandblasted, sandblasted and acid-etched, hyaluronic acid-coated (HYA), hydroxyapatite-coated (HA), and machined-in an experimental sheep model at 1- and 3-month examinations. One hundred sixty dental implants were placed in the left and right tibias of 16 sheep. Five experimental groups were designed. Eight animals (80 implants) were used for biomechanical tests of reverse torque analysis and resonance frequency analysis (RFA). Eight of them (80 implants) were used for the evaluation of bone-to-implant contact (BIC) percentage in histomorphometric analysis. Forty of 80 implants (8 implants for each group) were used at 1-month examinations, and the remaining 40 (8 implants for each group) implants were used at 3-month examinations in the biomechanical test group and histomorphometric examination group, separately. Intergroup analysis at the 3-month followup showed that the increase in the implant stability quotient (ISQ) value was statistically significant for only the HYA group (P < .05). According to ISQ values at 1 and 3 months, group HYA showed statistically higher values at the 1 and 3-month examinations (P < .05). Groups HYA and HA had statistically higher reverse torque values than other groups at the 1-month examination (P < .05). At the 3-month evaluation, the HYA group showed significantly higher reverse torque values compared to other groups (P < .05). The BIC values of the sandblasted and acid-etched, HYA, and HA groups were significantly higher than the sandblasted and machined groups at the 1- and 3-month examinations (P < .05). The BIC value for the HA group showed decreased value at the 3-month examination compared to the 1-month examination (P < .05). The RFA, reverse torque, and histomorphometric analysis at 1- and 3-month examinations show that dental implants coated with HYA may have increased potential for osseointegration compared to dental implants with sandblasted, sandblasted and acid-etched, machined, and HA-coated surfaces. Int J Oral Maxillofac Implants 2023;38:583-590. doi: 10.11607/jomi.9935.

An invivo preclinical study assessing biocompatibility of Pd-based bulk metallicglass.

The bulk metallic glass (BMG), Pd79Ag3.5P6Si9.5Ge2, has a high fracture toughness and has been found to accommodate post-yield stress, unlike most other BMG. Moreover, due to its greater noble gas composition it has a intrinsic corrosion resistance, ideal for dental and orthopedic implants. This present study aimed to evaluate the invivo application of Pd79Ag3.5P6Si9.5Ge2 in a large translational sheep model to assess its efficacy to be utilized as an endosteal device. Twelve implants in the form of cylindrical rods (3 mm in diameter) were produced through rapid quenching. Each sheep (n = 12) received one osteotomy in the mandibular region using rotary instrumentation, which was filled with Pd79Ag3.5P6Si9.5Ge2. After 6- and 24-weeks the animals were euthanized, and samples collected en bloc to conduct histomorphometric analysis. The degree of osseointegration were assessed through bone-to-implant contact (BIC). All samples revealed favorable BIC along with with fibrous connective tissue layers at both 6- and 24-weeks. Bone along with interfacial remodeling was observed in proximity with the metallic glass surface at 6 weeks with higher degrees of bone organization being observed at the later healing time, 24 weeks. The synthesized BMG, given its unique combination of toughness and strength, revealed potential to serve as an alternative to commonly used Ti alloys.

Sequential osseointegration of a novel implant system based on 3D printing in comparison with conventional titanium implants

To evaluate the sequential osseointegration of a novel titanium implant system based on a 3D printing technology in comparison with conventional titanium implants. Two novel titanium implants based on 3D printing were tested in the mandible of eight Beagle dogs. As a control, two different commercially available titanium implants were used. The implants were staged to accommodate healing periods of 2 and 6 weeks. The primary outcome variable was bone-to-implant contact (BIC) in non-decalcified tissue sections and micro-CT analysis. Histomorphometrically, the proportions of tissues adjacent to the implant surfaces were similar for all implants, whereas the BIC percentage of new mineralized bone was greater for the control implants after both 2 and 6 weeks (p < .05). Micro-CT analysis revealed increasing osseous volume and BIC from 2 to 6 weeks. In contrast to the histomorphometry, the BIC evaluation with the micro-CT data revealed a significantly higher BIC for the two test implants compared with controls (p < .001). The analysis of the total implant surface area disclosed a value that was approximately double as high for the test compared to the control implants. The novel titanium implant system based on 3D printing yielded values for osseointegration that were adequate and satisfactory. The higher percentage of new mineralized bone in the control implants is explained by the fact of a completely different three-dimensional surface area.

IMPROVEMENT IN OSTEOCONDUCTIVITY OF MINISCREW IMPLANTS BY THE BIOMIMETIC CALCIUM PHOSPHATE COATINGS IN THE PRESENCE AND ABSENCE OF BOVINE SERUM ALBUMIN

Miniscrew implants (MSIs) are widely used to provide absolute anchorage for the orthodontic treatment. However, the application of MSIs is limited by the relatively high failure rate (22.86%). In this study, we wished to investigate the effects of amorphous and crystalline biomimetic calcium phosphate coating on the surfaces of MSIs with or without the incorporated BSA for the osteointegration process with an aim to facilitate the early loading of MSIs.Amorphous and crystalline coatings were prepared on titanium mini-pin implants. Characterizations of coatings were examined by Scanning electron microscopy (SEM), Confocal laser-scanning dual-channel-fluorescence microscopy (CLSM) and Fourier-transform infrared spectroscopy (FTIR). The loading and release kinetics of bovine serum albumin (BSA) were evaluated by Enzyme linked immunosorbent assay (ELISA). Activity of alkaline phosphate (ALP) was measured by using the primary osteoblasts. In vivo, a model of metaphyseal tibial implantation in rats was used (n=6 rats per group). We had 6 different groups: no coating no BSA, no coating but with surface adsorption of BSA and incorporation of BSA in the biomimetic coating in the amorphous and crystalline coatings. Time points were 3 days, 1, 2 and 4 weeks. Histological and histomorphometric analysis were performed and the bone to implant contact (BIC) of each group was compared.In vitro, the incorporation of BSA changed the crystalline coating from sharp plates into curly plates, and the crystalline coating showed slow-release profile. The incorporation of BSA in crystalline coating significantly decreased the activity of ALP in vitro. In vivo study, the earliest significant increase of BIC appeared in crystalline coating group at one week.The crystalline coating can serve as a carrier and slow release system for the bioactive agent and accelerate osteoconductivity at early stage in vivo. The presence of BSA is not favorable for the early establishment of osteointegration.

Osseointegration of Titanium Implants in a Botox-Induced Muscle Paralysis Rat Model Is Sensitive to Surface Topography and Semaphorin 3A Treatment.

Reduced skeletal loading associated with many conditions, such as neuromuscular injuries, can lead to bone fragility and may threaten the success of implant therapy. Our group has developed a botulinum toxin A (botox) injection model to imitate disease-reduced skeletal loading and reported that botox dramatically impaired the bone formation and osseointegration of titanium implants. Semaphorin 3A (sema3A) is an osteoprotective factor that increases bone formation and inhibits bone resorption, indicating its potential therapeutic role in improving osseointegration in vivo. We first evaluated the sema3A effect on whole bone morphology following botox injections by delivering sema3A via injection. We then evaluated the sema3A effect on the osseointegration of titanium implants with two different surface topographies by delivering sema3A to cortical bone defect sites prepared for implant insertion and above the implants after insertion using a copper-free click hydrogel that polymerizes rapidly in situ. Implants had hydrophobic smooth surfaces (PT) or multiscale biomimetic micro/nano topography (SLAnano). Sema3A rescued the botox-impaired bone formation. Furthermore, biomimetic Ti implants improved the bone-to-implant contact (BIC) and mechanical properties of the integrated bone in the botox-treated rats, which sema3A enhanced. This study demonstrated the value of biomimetic approaches combining multiscale topography and biologics in improving the clinical outcomes of implant therapy.

Impact of salivary contamination during implant placement with different surface characteristics in native and augmented bone: An in vivo study in sheep calvaria model.

The aim of this study was to evaluate whether salivary contamination during placement of implants with different surface characteristics affects osseointegration in native and in augmented bone areas. Forty eight implants with machined surface (MS) and 48 implants with moderately rough surface (RS) were tested in the calvaria of 12 sheep. At the first surgery, 64 bony critical defects were randomly created and were subsequently augmented with two materials (autogenous or bovine bone). After 5 weeks of graft healing, 8 implants were placed per sheep, in native bone and in the centre of the augmented defects. Forty eight implants were soaked with saliva before placement (contaminated group [CG]), while 48 implants were not (non-contaminated group [NCG]). Five weeks after implant placement, bone-to-implant contact (BIC) and bone material area fraction occupancy (BMAFO) were calculated histomorphometrically. Saliva contamination showed a significant negative effect (p=.000) on BIC, especially in augmented areas. RS showed significant positive effect on BIC, compared to MS (p=.000), while there were no significant differences for different bone conditions (p=.103). For BMAFO, the contamination showed a significantly negative affect (p=.000), while there were no significant differences for surface characteristics (p=.322) and for bone condition (p=.538). Saliva contamination during dental implant placement has a negative effect on osseointegration in augmented areas. Moderately rough surface has a possible advantage in the aspect of initial bone to implant contact. However, it seems to be advisable to avoid saliva contamination especially for implants placed in augmented bone areas.

A preclinical study comparing single- and double-root 3D-printed Ti–6Al–4V implants

Recently, double-root implants have been investigated using 3D-printed technology. Here, we investigated damping capacity, microcomputed tomographic (micro-CT) and histological analyses of double-root 3D-printed implants compared with single-root 3D printed implants. Single- and double-root 3D-printed implants were fabricated and placed at both sides of mandibular third and fourth premolars in four beagle dogs. The damping capacity was measured, and periapical X-rays were taken every 2 weeks for 12 weeks. The bone volume/tissue volume (BV/TV) and bone mineral density (BMD) around the implants were measured with micro-CT. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were measured in histological samples. The implant stability values between the groups were not significantly different, except at 4 and 12 weeks. The marginal bone changes were similar at the mesial and distal areas between the groups. The BV/TV and BMD values of the double-root 3D-printed implants showed no statistical difference through micro-CT analysis, but the double-root 3D-printed implants showed lower BIC and BAFO values through histomorphometric analysis compared to the single-root 3D-printed implants. Compared to single-root implants, 3D-printed double-root implants demonstrated comparable stability and bone remodeling around the fixtures, but the statistically significant bone loss in the furcation area remains problematic.

Nanostructured Calcium-Incorporated Surface Compared to Machined and SLA Dental Implants-A Split-Mouth Randomized Case/Double-Control Histological Human Study.

Implant surface topography is a key element in achieving osseointegration. Nanostructured surfaces have shown promising results in accelerating and improving bone healing around dental implants. The main objective of the present clinical and histological study is to compare, at 4 and 6 weeks, (w) bone-to-implant contact in implants having either machined surface (MAC), sandblasted, large grit, acid-etched implant surface (SLA) medium roughness surface or a nanostructured calcium-incorporated surface (XPEED®). 35 mini-implants of 3.5 × 8.5 mm with three different surface treatments (XPEED® (n = 16)-SLA (n = 13)-MAC (n = 6), were placed in the posterior maxilla of 11 patients (6 females and 5 males) then, retrieved at either 4 or 6w in a randomized split-mouth study design. The BIC rates measured at 4w and 6w respectively, were: 16.8% (±5.0) and 29.0% (±3.1) for MAC surface; 18.5% (±2.3) and 33.7% (±3.3) for SLA surface; 22.4% (±1.3) and 38.6% (±3.2) for XPEED® surface. In all types of investigated surfaces, the time factor appeared to significantly increase the bone to implant contact (BIC) rate (p &lt; 0.05). XPEED® surface showed significantly higher BIC values when compared to both SLA and MAC values at 4w (p &lt; 0.05). Also, at 6w, both roughened surfaces (SLA and XPEED®) showed significantly higher values (p &lt; 0.05) than turned surface (MAC). Nanostructured Calcium titanate coating is able to enhance bone deposition around implants at early healing stages.

Biologic Bone Behavior During the Osseointegration Process: Histologic, Histomorphometric, and SEM-EDX Evaluations.

This study evaluated bone behavior during dynamic osseointegration. A total of 12 implants were placed in sheep tibia and analyzed at 15, 30, 60, and 90 days. Quantitative and qualitative bone behaviors were evaluated with histologic, histomorphometric, Alizarin Red S, and SEM-EDX (scanning electron microscopy with energy-dispersive x-ray spectroscopy) analysis. Twenty microanalyses were performed in chambers 1, 3, and 5 (a chamber is the distinctive space/bone volume between two coils of the implant screw) in distinctive zones: the titanium-bone interface (zone A), the middle chamber-bone front (zone B), the bone-surgical threading interface (zone C), and native bone (zone D; used as a control). The dynamic osseointegration index (DOI) and bone quality index (BQI) with calcium/phosphorus (Ca/P) content were detected to evaluate the osseointegration quality, bone-to-implant contact (BIC), and bone density around implants. At 15 days, initial bone formation with osteoid matrix deposition and different color intensities were observed (means: BIC = 23.3% ± 3.9%; DOI = 1.55). SEM-EDX analysis showed low mineralized bone/bone marrow with a very low Ca/P mean value. At 30 days, high new bone deposition with higher color intensity in the crestal portion was recorded (BIC = 77.3% ± 0.4%; DOI = 2.58). At 90 days, tight BIC to the middle and apical implant portions were detected, as well as several osteon structures in the crestal portion (BIC = 86.4% ± 0.6%; DOI = 0.96). During all observed time periods, the BQI showed 25% more Ca/P in zone A. Greater maturation degree and lower BQI were seen at zone A compared to the other zones. After 15 and 30 days, zones B and C (except for P in zone B) showed BQIs slightly over 50% and around 75%, respectively, confirming a progressively higher degree of bone maturation that proceeds with the osseointegration process. After 90 days, the BQI values of zones B and C (greater than 70% in zone B and around 90% in zone C) confirmed the bone mineralization and maturation process and an acceleration of implant osseointegration, while a lower BQI value (25%) was recorded in zone A. This study shows osseointegration as a variable dynamic process with a higher bone deposition in contact with the implant surface during the early phase, while in the active and later osseointegration times, the bone quality maturation showed higher values only "at distance" (growth of native bone to the implant surface, observed later in the osseointegration process). After 3 months (before loading), the BQI evaluation was lower (25%) in zone A, confirming that the healing and maturation process of the bone cannot be considered complete.

A Novel Method to Achieve Preferable Bone-to-Implant Contact Area of Zygomatic Implants in Rehabilitation of Severely Atrophied Maxilla.

Purpose: To propose and evaluate a novel method for achieving a favorable bone-to-implant contact (BIC) area for zygomatic implants (ZIs). Materials and Methods: Patients who needed ZIs to restore a severely atrophied maxilla were recruited. In preoperative virtual planning, an algorithm was utilized to find the ZI trajectory that would achieve the largest BIC area with a predefined entry point on the alveolar ridge. The surgery was conducted according to the preoperative plan with the assistance of real-time navigation. Area BIC (A-BIC), linear BIC (L-BIC), distance from implant to infraorbital margin (DIO), distance from implant to infratemporal fossa (DIT), implant exit section, and deviation of the real-time navigated surgery were measured and compared between the preoperative plan and the placed ZIs. The patients were followed up for 6 months. Results: Overall, 11 patients with 21 ZIs were included. The A-BICs and L-BICs were significantly higher in the preoperative plan than in the placed implants (P < .05). Meanwhile, there were no significant differences in DIO or DIT. The planned-placed deviation was 2.31 ± 1.26 mm for the entry, 3.41 ± 1.77 mm for the exit, and 3.06 ± 1.68 degrees for the angle. All ZIs survived to the 6-month follow-up. Conclusion: This novel method can virtually calculate the trajectory of ZIs and transfer the preoperative plan to surgery to acquire a favorable BIC area. The actual positions of placed ZIs were slightly deviated from the ideal due to navigation errors.