Bone‐supportive behavior of microplasma‐sprayed CaP‐coated implants: mechanical and histological outcome in the goat

Background: New microplasma spray (MPS) equipment to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this apparatus, it is possible to spray fine particles, as well as to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate is reduced. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying of dental implants. Additionally, the low level of noise (25–50 dB) and hardly any dust makes it possible to operate the MSE under normal workroom conditions. Objective: The aim of this study was to examine the biological properties of different MPS – CaP coatings on titanium implants when inserted into the femoral condyle of goats. Material and methods: For histomorphometrical evaluation as well as mechanical testing, 48 screw‐type titanium implants were inserted into the femoral condyles of 12 goats each. The implants were either coated with a conventionally plasma‐sprayed CaP ceramic, MPS CaP ceramic, or acid‐etched without an additional CaP coating. Six and 12 weeks after implantation, the animals were sacrificed and bone‐to‐implant contact, amount of bone, as well as mechanical bone fixation were evaluated. Results: For bone‐to‐implant contact no statistically significant difference was found between the different CaP coatings. However, statistically significant differences were found between non‐coated, acid‐etched titanium implants and CaP‐coated implants after 6 and 12 weeks of healing. The bone values were not statistically significantly different between the different CaP coatings at 6 and 12 weeks. Furthermore, CaP ceramic‐coated implants showed statistically significantly higher torque values compared with the non‐coated implants after 6 and at 12 weeks of healing. No significant differences existed between the various types of CaP coatings. Conclusion: On the basis of our observations, we conclude that conventionally plasma‐sprayed CaP ceramic‐coated implants, as well as MPS‐coated implants have a comparable effect on adjacent bone response. To cite this article:
Junker R, Manders PJD, Wolke J, Borisov Y, Jansen JA. Bone‐supportive behavior of microplasma‐sprayed CaP‐coated implants: mechanical and histological outcome in the goat.
Clin. Oral Impl. Res. 21 , 2010; 189–200.
doi: 10.1111/j.1600‐0501.2009.01819.x     

Bone reaction adjacent to microplasma‐sprayed CaP‐coated oral implants subjected to occlusal load,an experimental study in the dog. Part I: short‐term results

Background: A new microplasma spraying equipment (MSE) to deposit calcium phosphate ceramic (CaP) coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate is diminished. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying for dental implants. Also, the low level of noise (25–50 dB) and hardly any dust makes it possible to operate MSE under conditions of normal workrooms. Objective: The aim was to investigate, in a mandibular dog model, bone biological properties and the occlusal loading effects of titanium implants provided with newly developed microplasma‐sprayed CaP coatings. Material and methods: For histomorphometrical evaluation, 48 screw‐type titanium implants were inserted into the mandibles of six adult beagle dogs. The implants were either acid etched without additional coating, coated with a conventionally plasma‐sprayed CaP ceramic, coated with a microplasma‐sprayed CaP ceramic or with a microplasma‐sprayed coating at the apical part only. To assess the effect of occlusal loading, a split‐mouth design was used. Six weeks after implantation, the implants in one half of the mandible of each dog were functionally loaded, while the contra lateral implants served as control. Six weeks after loading, the animals were sacrificed and bone‐to‐implant contact as well as the amount of bone around the implants were assessed. Results: Irrespective of surface and functional load, no statistically significant differences (P>0.05) were found either for bone‐to‐implant contact or for the amount of bone between the various implant surfaces. On the other hand, functional loading of the non‐coated implants was associated with a tendency towards crestal bone loss. Conclusion: Within the limits of the experiment, we conclude that functional loading of MPS CaP coatings induces a favorable bone response, and furthermore, that the bone response, irrespective of the loading condition, does not differ from conventional plasma‐sprayed CaP coatings. To cite this article:
Junker R, Manders PJD, Wolke J, Borisov Y, Jansen JA. Bone reaction adjacent to microplasma‐sprayed CaP‐coated oral implants subjected to occlusal load, an experimental study in the dog. Part I: Short‐term results.
Clin. Oral Impl. Res. 21 , 2010; 1251–1263.
doi: 10.1111/j.1600‐0501.2010.01940.x     

Osseointegration of one‐piece zirconia implants compared with a titanium implant of identical design: a histomorphometric study in the dog

Objective: The aim of this study was to evaluate osseointegration of one‐piece zirconia vs. titanium implants depending on their insertion depth by histomorphometry. Material and methods: Four one‐piece implants of identical geometry were inserted on each side of six mongrel dogs: (1) an uncoated zirconia implant, (2) a zirconia implant coated with a calcium‐liberating titanium oxide coating, (3) a titanium implant and (4) an experimental implant made of a synthetic material (polyetheretherketone). In a split‐mouth manner they were inserted in submerged and non‐submerged gingival healing modes. After 4 months, dissected blocks were stained with toluidine blue in order to histologically assess the bone‐to‐implant contact (BIC) rates and the bone levels (BL) of the implants. Results: All 48 implants were osseointegrated clinically and histologically. Histomorphometrically, BL in the crestal implant part did not differ significantly with regard to material type or healing modality. The submerged coated zirconia implants tended to offer the most stable crestal BL. The histometric results reflected the different healing modes by establishing different BL. The median BIC of the apical implant part of the zirconia and titanium group amounted to 59.2% for uncoated zirconia, 58.3% for coated zirconia, 26.8% for the synthetic material and 41.2% for titanium implants. Conclusions: Within the limits of this animal study, it is concluded that zirconia implants are capable of establishing close BIC rates similar to what is known from the osseointegration behaviour of titanium implants with the same surface modification and roughness. To cite this article:
Koch FP, Weng D, Krämer S, Biesterfeld S, Jahn‐Eimermacher A, Wagner W. Osseointegration of one‐piece zirconia implants compared with a titanium implant of identical design: a histomorphometric study in the dog.
Clin. Oral Impl. Res. 21 , 2010; 350–356.
doi: 10.1111/j.1600‐0501.2009.01832.x     

Bone regeneration in dehiscence-type defects at non-submerged and submerged chemically modified (SLActive) and conventional SLA titanium implants: an immunohistochemical study in dogs

Objectives: The aim of the present study was to evaluate bone regeneration in dehiscence‐type defects at non‐submerged and submerged titanium implants with chemically modified (mod) and conventional sandblasted/acid‐etched (SLA) surfaces. Material and Methods: Standardized buccal dehiscence defects were surgically created following implant site preparation in both the upper and lower jaws of 12 beagle dogs. Both types of implants were randomly assigned to either a non‐submerged or a submerged healing procedure. After 1, 2, 4, and 8 weeks, dissected blocks were processed for histomorphometrical [e.g. new bone height (NBH), per cent linear fill (PLF), percentage of bone to implant contact (BIC‐D), area of new bone fill (BF)] and immunohistochemical analysis. Results: At 8 weeks, non‐submerged and submerged SLA implants revealed significantly lower mean NBH (1.1±0.8–1.9±1.2 mm), PLF (27.7±20.3–46.0±28.5%), BIC‐D (26.8±10.4–46.2±16.2%), and BF (1.3±0.9–3.4±2.8 mm²) values than respective modSLA implants [NBH (2.6±0.8–4.3±0.1 mm), PLF (64.2±19.4–107.2±4.7%), BIC‐D (67.5±18.8–82.1±14.8%), BF (2.9±1.0–6.7±1.1 mm²)]. Within modSLA groups, significantly highest BF values were observed at submerged implants. Conclusion: It was concluded that (i) modSLA titanium surfaces promoted bone regeneration in acute‐type buccal dehiscence defects and (ii) a submerged healing procedure improved the outcome of healing additionally.     

Peripheral quantitative computer tomographic,histomorphometric, and removal torque analyses of two different non‐coated implants in a rabbit model

Objective: The objectives of this study were (1) to investigate the bone–tissue response to zirconia and titanium implants at the implant‐to‐bone interface and at the periosteal level and (2) to quantitatively measure the mineral density of the peri‐implant bone using peripheral quantitative computer tomography (pQCT). Material and methods: Ten 3.5 mm × 6.6 mm screw‐shaped threaded implants fabricated from titanium and zirconia were inserted into the mid‐tibial diaphysis of five male New Zealand white rabbits. Calcein green was administered at 4 weeks post‐implantation. The animals were sacrificed after 6 weeks and implants were retrieved and analyzed in terms of bone‐to‐implant contact (BIC), bone area (BA), mineralized surface (MS) percentage, inter‐thread calcein labels, removal torque (RT) values, as well as pQCT measurements. Findings: No statistically significant differences were detected between the zirconia and titanium implants in terms of BIC, RT, and pQCT. However, statistically significant higher BA and MS levels were found in the titanium group, while the higher amount of calcein labels occupying the threads were found in the zirconium group. Significant differences were also found in the quantity and the composition of bone at the bone–implant interfacial area vs. the region 1.5 mm away from the bone–implant interface, irrespective of the implant type. Conclusion: Zirconia implants demonstrated a lower bone remodeling activity in the periosteal region. The bone at the bone–implant interface shows a significantly lower cortical bone density, a higher trabecular density, and trabecular mineral content. Finally, zirconia and titanium implants showed similar bone–implant responses in terms of BIC and RT. To cite this article:
Shin D, Blanchard SB, Ito M, Chu T‐MG. Peripheral quantitative computer tomographic, histomorphometric, and removal torque analyses of two different non‐coated implants in a rabbit model.
Clin. Oral Impl. Res. 22 , 2011; 242–250.
doi: 10.1111/j.1600‐0501.2010.01980.x     

Biofunctionalization of titanium implants with a biomimetic active peptide (P‐15) promotes early osseointegration

Objectives: The early stages of peri‐implant bone formation play an essential role in the osseointegration and long‐term success of dental implants. By incorporating bioactive coatings, this biofunctionalization of implant surfaces may enhance the attachment of the implant to the surrounding bone and stimulate bone regeneration. Material and methods: To demonstrate faster osseointegration, the surfaces of dental implants were grit‐blasted and acid‐etched. They were then coated with hydroxyapatite (HA) and experimental implants were further coated with a biomimetic active peptide (P‐15) in one of two concentrations. These biofunctionalized samples and controls with no peptide were placed in the forehead region of 12 adult pigs. Six animals were evaluated for a period of 14 or 30 days. Results: Histomorphometric analysis demonstrated that the implants with the high concentration of P‐15 had significantly higher percentage of bone‐to‐implant contact (BIC) at 14 (P=0.018) and 30 (P=0.015) days compared with the other groups. Both concentrations of P‐15 showed increased peri‐implant bone density compared to the control group at 30 days. Conclusion: Biofunctionalization of the implant surface with a biomimetic active peptide leads to significantly increased BIC rates at 14 and 30 days and higher peri‐implant bone density at 30 days. To cite this article:
Lutz R, Srour S, Nonhoff J, Weisel T, Damien CJ, Schlegel KA. Biofunctionalization of titanium implants with a biomimetic active peptide (P‐15) promotes early osseointegration.
Clin. Oral Impl. Res. 21 , 2010; 726–734.
doi: 10.1111/j.1600‐0501.2009.01904.x     

Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model

Objectives: The aim of the present study was to evaluate a Ca–P coated implant surface in a rabbit model. The Ca–P surface (test) was compared to the titanium porous oxide surface (control) in terms of bone‐to‐implant contact (BIC) and removal torque value. Materials and methods: Two hundred and sixteen dental implants were inserted in the tibia and in the femur of 36 rabbits. One hundred and eight were represented by Ca–P oxidized surface implant and other 108 were titanium porous oxide surface modified implants. Each rabbit received six implants. Animals were sacrificed after 2, 4 and 9 weeks of healing. Each group included 12 rabbits. The femoral implant and the proximal implant of the tibia of each animal were subjected to the histologic analysis and the distal implants of the tibia underwent removal torque test (RTQ). Results: Histological analysis in terms of BIC and RTQ did not revealed any significant difference between the Ca–P oxidized surface and the oxidized surface at 2 and 4 weeks. At 9 weeks, the oxidized surface demonstrated better results in terms of RTQ in the tibia. Conclusion: In conclusion, findings from the present study suggested that the Ca–P coating had no beneficial effect in improving bonding strength at the bone–implant interface either at 2, 4 and 9 weeks. To cite this article:
Fontana F, Rocchietta I, Addis A, Schupbach P, Zanotti G, Simion M. Effects of a calcium phosphate coating on the osseointegration of endosseous implants in a rabbit model
Clin. Oral Impl. Res. 22 , 2011; 760–766
doi: 10.1111/j.1600‐0501.2010.02056.x     

Bone reaction adjacent to microplasma-sprayed calcium phosphate-coated oral implants subjected to an occlusal load, an experimental study in the dog

Background: A new microplasma spraying equipment (MSE) to deposit calcium phosphate (CaP) ceramic coatings onto titanium substrates has been developed. With this system, it is possible to spray fine particles and to apply textured hydroxylapatite coatings onto titanium surfaces. Moreover, due to the low heat power of the microplasma jet, overheating of the powder particles as well as excessive local overheating of the substrate are diminished. Furthermore, because of the small laminar plasma jet, it is possible to achieve high spray efficiency in the case of spraying for dental implants. Also, the low level of noise (25–50 dB) and hardly any dust makes it possible to operate MSE under conditions of normal workrooms. Objective: The aim was to investigate, in a mandibular dog model, the effect of functional load on soft‐tissue adaptation as well as crestal bone‐level changes around titanium implants provided with newly developed microplasma‐sprayed CaP coatings. Material and methods: For histomorphometrical evaluation, 56 screw‐type titanium implants were inserted into the mandibles of seven adult Beagle dogs. The implants were either acid etched without an additional coating, coated with a conventionally plasma‐sprayed CaP ceramic (PS), coated with a microplasma‐sprayed CaP ceramic (MPS) or with a microplasma‐sprayed coating at only the apical part (aMPS). To assess the effect of occlusal loading, a split‐mouth design was used. Six weeks after implantation, the implants in one half of the mandible of each dog were functionally loaded whereas the contra lateral implants served as control. One year after loading, the animals were sacrificed. Soft‐tissue dimension as well as marginal bone level were histologically assessed. Results: Histometric analysis of undecalcified histologic sections included the evaluation of the sulcus depth, the dimension of the junctional epithelium and the connective tissue as well as the first bone‐to‐implant contact. For MPS‐surfaced implants, functional loading was associated with – compared with the non‐loaded state – unchanged soft‐tissue dimension. Furthermore, the soft‐tissue dimension did not differ from the dimensions around non‐coated, PS and aMPS implants. Moreover, the first bone‐to‐implant contact was not significantly altered by functional loading and comparable non‐coated, PS and aMPS implants. Conclusion: Within the limits of the experiment, we conclude that, in comparison, functional loading does not affect the marginal soft‐tissue response to MPS CaP‐coated implants. However, in comparison, functional loading might affect marginal bone response to MPS CaP‐coated implants. To cite this article:
Junker R, Manders PJD, Wolke J, Borisov Y, Braceras I, Jansen JA. Bone reaction adjacent to microplasma‐sprayed calcium phosphate‐coated oral implants subjected to occlusal load, an experimental study in the dog. Clin. Oral Impl. Res. 22 , 2011; 135–142.
doi: 10.1111/j.1600‐0501.2010.02025.x     

Oral implants placed in bone defects treated with Bio‐Oss®, Ostim®‐Paste or PerioGlas: an experimental study in the rabbit tibiae

Objectives: To compare the histological features of bone filled with Bio‐Oss^®, Ostim‐Paste^® or PerioGlas placed in defects in the rabbit tibiae by evaluating bone tissue composition and the integration of titanium implants placed in the grafted bone. Material and methods: Two cylindrical bone defects, about 4 mm in diameter and 6 mm in depth, were created in the tibiae of 10 rabbits. The defects were filled with either Bio‐Oss^®, PerioGlas, Ostim^®‐Paste or left untreated, and covered with a collagen membrane. Six weeks later, one titanium sandblasted and acid‐etched (SLA) implant was inserted at the centre of each previously created defect. The animals were sacrificed after 6 weeks of healing. Results: Implants placed in bone previously grafted with Bio‐Oss^®, PerioGlas or Ostim^®‐Paste obtained a larger extent of osseointegration, although not statistically significant, than implants placed in non‐grafted bone. The three grafting materials seemed to perform in a similar way concerning their contribution towards implant osseointegration. All grafting materials appeared to be osteoconductive, thus leading to the formation of bridges of mineralized bone extending from the cortical plate towards the implants surface through the graft scaffold. Conclusions: Grafting with the above‐mentioned biomaterials did not add any advantage to the osseointegration of titanium SLA implants in a self‐contained defect.     

In vivo performance of zirconia and titanium implants: a histomorphometric study in mini pig maxillae

Objectives: To compare the bone tissue response to surface‐modified zirconia (ZrO₂) and titanium implants. Methods: Cylindrical low‐pressure injection moulded zirconia (ZrO₂) implants were produced with an acid‐etched surface. Titanium implants with identical shape, sandblasted and acid‐etched surface (SLA) served as controls. Eighteen adult miniature pigs received both implant types in the maxilla 6 months after extraction of the canines and incisors. The animals were euthanized after 4, 8 and 12 weeks and 16 zirconia and 18 titanium implants with the surrounding tissue were retrieved, embedded in methylmethacrylate and stained with Giemsa–Eosin. The stained sections were digitized and histomorphometrically analysed with regard to peri‐implant bone density (bone volume/total volume) and bone–implant contact (BIC) ratio. Statistical analysis was performed using Mann–Whitney' U‐test. Results: Histomorphometrical analysis showed direct osseous integration for both materials. ZrO₂ implants revealed mean peri‐implant bone density values of 60.4% (SD ± 9.9) at 4 weeks, 65.4% (SD ± 13.8) at 8 weeks, and 63.3% (SD ± 21.5) at 12 weeks after implantation, whereas Ti‐SLA implants demonstrated mean values of 61.1% (SD ± 6.2), 63.6% (SD ± 6.8) and 68.2% (SD ± 5.8) at corresponding time intervals. Concerning the BIC ratio, the mean values for ZrO₂ ranged between 67.1% (SD ± 21.1) and 70% (SD ± 14.5) and for Ti‐SLA between 64.7% (SD ± 9.4) and 83.7% (SD ± 10.3). For the two parameters investigated, no significant differences between both types of implants could be detected at any time point. Conclusion: The results indicate that there was no difference in osseointegration between ZrO₂ implants and Ti‐SLA controls regarding peri‐implant bone density and BIC ratio. To cite this article :
Gahlert M, Roehling S, Sprecher CM, Kniha H, Milz S, Bormann K. In vivo performance of zirconia and titanium implants: a histomorphometric study in mini pig maxillae.
Clin. Oral Impl. Res. 23 , 2012; 281–286.
doi: 10.1111/j.1600‐0501.2011.02157.x     

Implant-guided vertical bone growth in the mini-pig

Objective: To attain and describe guided vertical bone regeneration around titanium (Ti) and titanium zirconium (Ti–Zr) dental implants utilizing non‐glycosylated recombinant human bone morphogenetic protein‐2 (ng/rhBMP‐2), biomaterial scaffolds and a scaffold retainer. Materials and methods: Thirty‐two modified Straumann TE implants were partially embedded in the mandibles of eight adult mini‐pigs. Pre‐shaped resorbable scaffolds were placed around the implant and shielded and stabilized with a newly developed Ti custom scaffold retainer (umbrella) or wide‐neck (WN) healing caps to stabilize the scaffold. Ng/rhBMP‐2 (50 μg) was applied to the supracrestal portion of the implant or incorporated within the scaffold. At 9 weeks, soft tissue healing was assessed. Vertical bone regeneration outcomes including bone height, bone‐to‐implant contact (BIC) and bone volume were assessed by micro‐computed tomography and histology. Results: Soft tissue healing at the test sites (+ng/rhBMP‐2/+scaffold) appeared to be substantially better than the control sites (?ng/rhBMP‐2/?scaffold). Bone height, BIC percentage and bone volume were all similar regardless of whether WN healing caps or umbrella scaffold stabilization was used for all biomaterial scaffolds tested. WN healing cap test sites showed greater new bone height and BIC as compared with aggregate data from the control sites (P=0.05). Comparison of aggregate data from the umbrella test sites showed greater BIC and new bone volume as compared with aggregate data from the control sites(P=0.05). Conclusion: Vertical bone regeneration was successfully attained utilizing ng/rhBMP‐2, biomaterial scaffolds and a scaffold retainer.     

Influence of Implant Neck Surface and Placement Depth on Crestal Bone Changes Around Platform‐Switched Implants: A Clinical and Radiographic Study in Dogs

Background: The aim of this animal study is to analyze bone remodeling around platform‐switching (PS) implants with and without a machined (MACH) collar placed at different levels in relation to the crestal bone in a canine model. Methods: All mandibular premolars and first molars were extracted in five dogs. After 6 months, grit‐blasted acid‐etched (GBAE) PS implants with and without a MACH neck were randomly inserted in each hemimandible, positioning the implant‐abutment interface in either a supracrestal (+1.5 mm), equicrestal, or subcrestal (?1.5 mm) position, and healing abutments were connected. Implant abutments were dis/reconnected at 12, 14, 16, and 18 weeks after implant placement. After 6 months of healing, animals were sacrificed. Clinical parameters and periapical radiographs were registered on the day of implant placement, at 2 months, at every abutment dis/reconnection, and at sacrifice. Crestal bone changes were calculated and defined as the primary outcome variable. Results: When crestal bone changes from implant placement to 6 months were compared between MACH and GBAE groups, no significant differences were encountered except for implants placed in an equicrestal position (P = 0.04). However, multivariable regression analysis revealed no significant differences between MACH and GBAE implants placed in a supracrestal (β = ?0.08; P = 0.45), equicrestal (β = ?0.05; P = 0.50), or subcrestal (β = ?0.13; P = 0.19) position. Conclusion: Surface treatment of the implant neck had no significant influence on crestal bone changes around PS implants with and without a MACH collar.     

Peri‐Implant Endosseous Healing Properties of Dual Acid‐Etched Mini‐Implants with a Nanometer‐Sized Deposition of CaP: A Histological and Histomorphometric Human Study

Purpose: The aim of this histological and histomorphometric study was to compare the early peri‐implant endosseous healing properties of a dual acid‐etched (DAE) surface (Osseotite®, Implant Innovations Inc., Palm Beach Gardens, FL, USA) with a DAE surface modified with nanometer‐sized calcium phosphate (CaP) particles (NanoTite?, Implant Innovations Inc.) in grafted and mature maxillary bone. Materials and Methods: Fifteen patients received two mini‐implants, 1 with DAE surface (control) and 1 with a DAE + CaP surface (test), to fixate an iliac crest bone graft to the maxilla. A part of each mini‐implant was in contact with the grafted bone and a part extended into the native maxillary bone. After a healing period of 3 months, the specimens were harvested and analyzed. Results: Overall, a trend was seen for stronger bone response around the test mini‐implants in the native bone of the maxilla. However, only the old bone particles measured by percentages of bone‐to‐implant contact and bone area were statistically significant (p = .025 and p = .042, respectively). Conclusions: The NanoTite surface increases the peri‐implant endosseous healing properties in the native bone of the maxilla compared with the Osseotite surface, while this difference was not visible in the bone graft area. This might be a result of the lower remodeling process of the graft.     

Short-term bone response to titanium implants coated with thin radiofrequent magnetron-sputtered hydroxyapatite in rabbits

Background: It has been suggested that calcium phosphate (CaP) coatings initiate faster bone growth around implants. A major concern about the viable use of these coatings has been their biologic performance related to the coating characteristics. Purpose: The purpose of this study was to investigate the early bone response to micron‐ and submicron‐thick hydroxya‐patite (HA) coatings in cortical and trabecular bone. Materials and Methods: CaP coatings were manufactured by magnetron sputtering. Heat treatment was subsequently used to increase the crystallinity of the coatings. Coatings were characterized by x‐ray diffraction, Fourier transform infrared spectroscopy, inductively coupled plasma optical emission spectroscopy (ICP‐OES), and stylus profilometry. Four types of CaP‐coated implants were used (0.1 urn and 2.0 μm amorphous; 0.1 um and 2.0 μn crystalline); uncoated machined commercially pure titanium implants served as controls. Four hundred eighty implants were randomly placed in 60 rabbits. Ten animals were followed up for 1 week, 10 for 3 weeks, and 40 for 6 weeks. The bone response was histomorphometrically evaluated. Results: Coatings with a CaP ratio very close to that of HA were produced. Crystalline coatings significantly improved the early bone‐implant contact whereas the amorphous‐coated implants behaved similarly to uncoated titanium. Conclusions: Crystalline CaP coatings 100 nm thick on titanium implants elicited an improved early bone response compared with that of uncoated titanium implants. No further improvement in the bone response was observed with 2 μm coatings.     

Thin Bioactive Ceramic‐Coated Alumina‐Blasted/Acid‐Etched Implant Surface Enhances Biomechanical Fixation of Implants: An Experimental Study in Dogs

Background: Thin bioceramic coatings have been regarded as potential substitutes for plasma‐sprayed hydroxyapatite coatings. Purpose: This study tested the hypothesis that a thin bioactive ceramic coating deposition on an alumina‐blasted/acid‐etched (AB/AE) surface would positively affect the biomechanical fixation and bone‐to‐implant contact (BIC) of plateau root form implants. Materials and Methods: Implants of two different lengths (i.e., 4.5 × 11 mm long, n = 36) and 4.5 × 6 mm (short, n = 36) and two different surfaces, that is, control (AB/AE) and test (AB/AE + 300 – 500 nm bioactive ceramic coating), were placed in the proximal tibiae of six beagle dogs. The implants were retrieved for analyses 2 and 4 weeks after placement. The implants in bone specimens were subjected to torque loads until a 10% drop of the maximum torque was recorded. The specimens were evaluated under optical microscopy for bone morphology and percent BIC. Statistical analysis was performed by a generalized linear mixed effects analysis of variance model and statistical significance set at p < 0.05. Results: Significantly higher torque‐to‐interface fracture levels for test surface groups of both lengths when compared to control surfaces were observed. No significant difference in BIC was observed between test and control implants of equal length. Histomorphological analysis showed higher degrees of bone organization between the plateaus of test implant surfaces at both implantation times. Conclusion: Because the presence of a thin bioactive ceramic coating on the surface did not affect BIC, but positively affected implant biomechanical fixation, the hypothesis was partially validated.     

The biomechanical analysis of relative position between implant and alveolar bone: finite element method

Background: The purpose of this study is to analyze biomechanical interactions in the alveolar bone surrounding implants with smaller‐diameter abutments by changing position of the fixture–abutment interface, loading direction, and thickness of cortical bone using the finite element method. Methods: Twenty different finite element models including four types of cortical bone thickness (0.5, 1, 1.5, and 2 mm) and five implant positions relative to bone crest (subcrestal 1, implant shoulder 1 mm below bone crest; subcrestal 0.5, implant shoulder 0.5 mm below bone crest; at crestal implant shoulder even with bone crest; supracrestal 0.5, implant shoulder 0.5 mm above bone crest; and supracrestal 1, implant shoulder 1 mm above bone crest) were analyzed. All models were simulated under two different loading angles (0 and 45 degrees) relative to the long axis of the implant, respectively. The three factors of implant position, loading type, and thickness of cortical bone were computed for all models. Results: The results revealed that loading type and implant position were the main factors affecting the stress distribution in bone. The stress values of implants in the supracrestal 1 position were higher than all other implant positions. Additionally, compared with models under axial load, the stress values of models under off‐axis load increased significantly. Conclusions: Both loading type and implant position were crucial for stress distribution in bone. The supracrestal 1 implant position may not be ideal to avoid overloading the alveolar bone surrounding implants.     

Influence of supracrestal tissue attachment thickness on radiographic bone level around dental implants: A systematic review and meta‐analysis

The present systematic review and meta‐analysis was carried out to determine the extent to which supracrestal tissue attachment (STA) thickness affects marginal bone loss (MBL) around dental implants. An electronic search was conducted in PubMed (MEDLINE), EMBASE, and complementary sources covering the period up to June 2018. The studies were meta‐analyzed based on implant position with respect to the alveolar bone crest (crestal/supracrestal). The MBL values were categorized according to STA width (thick/thin). Of the 1062 eligible titles, nine articles were included in the review. The implants were positioned crestal or supracrestal with respect to the alveolar ridge. The difference between (thin/thick) STA was statistically significant among analytical subsets in terms of lesser MBL (crestal‐positioned: weighted mean difference [WMD] = 0.52, 95% CI [0.03‐1.01]; P = 0.036; supracrestal‐positioned: WMD = 1.26; 95% CI [1.12‐1.39]; P = 0.00; pooled analysis: WMD = 0.73; 95% CI [0.033‐1.13]; P < 0.01). Implant positioning and patient age showed statistical significance in the meta‐regression analysis. The heterogeneity explained by age was R² = 39.8%. Despite its limitations, the present study demonstrates that implants with thin STA result in greater MBL. There is moderate certainty of the evidence for a large effect of MBL prevention “in favor” of a thick STA environment in crestal‐positioned implants and the pooled analysis, but lesser certainty when only supracrestal‐positioned implants are considered. No trials studying this topic in subcrestal‐positioned implants were found.     

Early bone apposition and 1‐year performance of the electrodeposited calcium phosphate coatings: an experimental study in rabbit femora

Objectives: The aim of this study was to investigate the early bone apposition and 1‐year performance of the electrodeposited calcium phosphate coatings with or without chitosan. Material and methods: Seventy‐two cylindrical implants with a length of 8 mm and a diameter of 3.3 mm were divided into three groups: electrodeposited calcium phosphate coated without chitosan, with chitosan, and an uncoated control. The implants adopted the special gap design and were inserted into the rabbit femora. After 2, 4, 26, and 52 weeks, the implants were retrieved and analyzed for bone formation, bone‐to‐implant contact, and coating degradation. Results: It was found that the coatings without chitosan had the highest bone contact at early time (P<0.05). The coatings with chitosan had the least bone formation within gaps after 2, 4, and 26 weeks of implantation (P<0.05). However, no difference was found among the three groups after 52 weeks. Both coatings showed degradation as early as 2 weeks post‐implantation. And after 52 weeks, most of the coatings had been degraded. There were no inflammatory reactions and hardly any osteoclasts around the implants and the coatings. The confocal laser scanning microscopy observation further demonstrated the different bone deposition characteristics. With scanning electron microscopy, no coatings could be found on both the implant surface and the bone interface. Conclusions: Bone apposition to both electrodeposited calcium phosphate coatings was different at early time but almost the same after 52 weeks. And both coatings showed early as well as a continued degradation in the rabbit femora. To cite this article:
Wang J, Sun C, Wang Y, Wang Y. Early bone apposition and 1‐year performance of the electrodeposited calcium phosphate coatings: an experimental study in rabbit femora.
Clin. Oral Impl. Res. 21 , 2010; 951–960.
doi: 10.1111/j.1600‐0501.2010.01935.x     

Rehabilitation of irradiated patients with chemically modified and conventional SLA implants: five‐year follow‐up

The aim of this study is to evaluate the clinical and radiological parameters of standard SLA surface implants compared to chemically modified hydrophilic SLActive implants in irradiated patients after the initial 12‐month loading period up to 5 years. Twenty patients with a mean age of 61·1 years were treated with dental implants after ablative surgery and radio‐chemotherapy of oral cancer. All patients were non‐smokers. The placement of 102 implants (50 SLA, 52 SLActive) was performed bilaterally according to a split‐mouth design. Mean crestal bone changes were evaluated using standardised orthopantomographies and clinical parameters. Data were analysed using a Kaplan–Meier curve, Mann–Whitney U‐test and two‐factorial non‐parametric analysis. The average observation period was 60 months. The amount of bone loss at the implant shoulder of SLA implants was mesial and distal 0·7 mm. The SLActive implants displayed a bone loss of mesial 0·6 mm as well as distal 0·7 mm after 5 years. Two SLA implants were lost before loading. One patient lost five implants due to recurrence of a tumour. The overall cumulative 12‐month, 3‐year and 5‐year survival rate of SLA implants was 92%, 80% and 75·8% and of SLActive implants 94·2%, 78·8% and 74·4%, respectively. Eighteen implants were considered lost because the patients had died. Sandblasted acid‐etched implants with or without a chemically modified surface can be used in irradiated patients with a high predictability of success. Lower implant survival rates in patients with irradiated oral cancer may be associated with systemic effects rather than peri‐implantitis.     

Effect of immediate or delayed loading following immediate placement of implants with a modified surface

Objective: To evaluate the effect of the timing of loading on bone‐to‐implant contact (BIC) following immediate placement of implants with a hydrophilic sandblasted, large‐grit and acid‐etched surface (modSLA) into fresh extraction sockets in a minipig model. Material and methods: Six minipigs were used in this study. In each hemi‐mandible, two conical shape implants (TE, Straumann implants) with a hydrophilic surface (modSLA) were placed in fresh extraction sockets. In one side of the mandible (control), two implants were immediately placed in fresh extraction sockets. The implants were loaded after 4 weeks of healing. At the contralateral side (test), two implants were immediately placed and loaded. After 8 weeks of healing, the animals were sacrificed and histologically analysed. Results: During the experimental period, no implants were lost and all of them presented to be osseointegrated. The percentage of BIC was similar in both groups: 66.1% and 65.1% for the control and test group, respectively. Furthermore, the distance from the shoulder of the implant to bone crest and the distance from the shoulder to the first BIC were similar in both groups. Conclusion: Immediate implant placement and loading showed similar BIC with immediate placement and delayed loading when implants with a modSLA surface were used. Both procedures showed similar buccal bone crest levels, which presented some resorption irrespective of the treatment modality. To cite this article:
Liñares A, Mardas N, Dard M, Donos N. Effect of immediate or delayed loading following immediate placement of implants with a modified surface.
Clin. Oral Impl. Res. 22 , 2011; 38–46.
doi: 10.1111/j.1600‐0501.2010.01988.x