Bone regeneration in dehiscence-type defects at chemically modified (SLActive) and conventional SLA titanium implants: a pilot study in dogs

OBJECTIVES: The aim of the present study was to evaluate bone regeneration in dehiscence-type defects at titanium implants with chemically modified (mod) and conventional sand-blasted/acid-etched (SLA) surfaces. MATERIAL AND METHODS: Standardized buccal dehiscence defects (height: 3 mm, width: 3 mm) were surgically created following implant site preparation in both the upper and lower jaws of four beagle dogs. modSLA and SLA implants were inserted bilaterally according to a split-mouth design. The animals were sacrificed after 2 and 12 weeks (n=2 animals each). Dissected blocks were processed for histomorphometrical analysis: defect length, new bone height (NBH), percent linear fill (PLF), percent of bone-to-implant contact (BIC-D) and area of new bone fill (BF). RESULTS: Wound healing at SLA implants was predominantly characterized by the formation of a dense connective tissue at 2 and 12 weeks, without significant increases in mean NBH, PLF, BIC-D or BF values. In contrast, modSLA implants exhibited a complete defect fill at 12 weeks following implant placement. In particular, histomorphometrical analysis revealed the following mean values at 12 weeks: NBH (3.2+/-0.3 mm), PLF (98%), BIC-D (82%) and BF (2.3+/-0.4 mm(2)). CONCLUSION: Within the limits of the present study, it was concluded that modSLA titanium surfaces may promote bone regeneration in acute-type buccal dehiscence defects at submerged implants.     

Efficacy of Using PDGF and Xenograft With or Without Collagen Membrane for Bone Regeneration Around Immediate Implants With Induced Dehiscence‐Type Defects: A Microcomputed Tomographic Study in Dogs

Background: Use of collagen membrane (CM) with xenograft and recombinant human platelet‐derived growth factor (rhPDGF) in guided bone regeneration (GBR) is debatable. The aim of this microcomputed tomographic experiment was to assess the efficacy of using PDGF and xenograft (with or without CM) for GBR around immediate implants with dehiscence defects. Methods: Ten beagle dogs underwent atraumatic bilateral second and fourth premolar extractions from both arches. A standardized dehiscence defect (6 × 3 mm) was created on the buccal bone and immediate implants were placed in distal sockets in each site. Animals were randomly divided into three groups: 1) group 1, xenograft with rhPDGF was placed and covered with CM; 2) group 2, xenograft with rhPDGF was placed over the defects; and 3) group 3, four immediate implants were associated with dehiscence (controls). After 16 weeks, animals were sacrificed and jaw segments were assessed for buccal bone thickness (BBT), buccal bone volume (BBV), vertical bone height (VBH), and bone‐to‐implant contact (BIC) using microcomputed tomography. Results: BBT was higher in group 2 (1.533 ± 0.89 mm) than group 1 (0.745 ± 0.322 mm) (P <0.001) and group 3 (0.257 ± 0.232 mm) (P <0.05). BBV was higher in group 2 (67.87 ± 19.83 mm³) than group 1 (42.47 ± 6.78 mm³) (P <0.05) and group 3 (19.12 ± 4.06 mm³) (P <0.001). VBH was higher in group 2 (6.36 ± 1.37 mm) than group 3 (0.00 ± 0.00 mm) (P <0.001). VBH was higher in group 1 (3.91 ± 2.68 mm) than group 3 (0.00 ± 0.00 mm) (P <0.05). BIC was higher in group 2 (67.25% ± 13.42%) than group 1 (36.25% ± 12.78%) (P <0.05) and group 3 (30.25% ± 7.27%) (P <0.01). Conclusion: GBR around immediate implants with dehiscence defects using PDGF and xenograft alone resulted in higher BBT, BBV, VBH, and BIC than when performed in combination with CM.     

Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs. Part 2: augmentation using bone graft substitutes

Objectives: To assess the influence of two barrier membranes and two bone graft substitutes on staged guided bone regeneration and osseointegration of titanium implants in dogs. Materials and methods: Saddle‐type defects were prepared in the lower jaws of 6 fox hounds and randomly filled with a natural bone mineral (NBM) and a biphasic calcium phosphate (SBC) and allocated to either an in situ gelling polyethylene glycol (PEG) or a collagen membrane (CM). At 8 weeks, modSLA titanium implants were inserted and left to heal in a submerged position. At 8+2 weeks, respectively, dissected blocks were processed for histomorphometrical analysis (e.g., mineralized tissue [MT], bone‐to‐implant contact [BIC]). Results: The mean MT values (mm²) and BIC values (%) tended to be higher in the PEG groups (MT: NBM [3.4±1.7]; SBC [4.2±2]/BIC: NBM [67.7±16.9]; SBC [66.9±17.8]) when compared with the corresponding CM groups (MT: NBM [2.5±0.8]; SBC [2.3±1.6]/BIC: NBM [54.1±22.6]; SBC [61±8.7]). These differences, however, did not reach statistical significance. Conclusion: It was concluded that all augmentation procedures investigated supported bone regeneration and staged osseointegration of modSLA titanium implants. To cite this article :
Mihatovic I, Becker J, Golubovic V, Hegewald A, Schwarz F. Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs. Part 2: augmentation using bone graft substitutes.
Clin Oral Impl Res. 23 , 2012; 308–315.
doi: 10.1111/j.1600‐0501.2011.02238.x     

Osseointegration and stability of a modified sand-blasted acid-etched implant: an experimental pilot study in sheep

Objective: The aim of this pilot study was to compare the early‐term osseointegration characteristics of standard (SLA) and modified sand‐blasted and acid‐etched (modSLA) implants in an experimental animal model. Material and methods: A total of 30 SLA and modSLA implants were placed to the tibiae of three sheep and the insertion torque value (ITV) and resonance frequency analysis (RFA) measurements were performed. RFA measurement was repeated on 3 and 6 weeks healed implants after which the animals were sacrificed for histomorphometric analysis. Bone‐to‐implant contact was assessed on the non‐decalcified sections. Six weeks healed implants were also subjected to the reverse torque test (RTT). Results were analyzed by the Friedman test, Kruskal–Wallis test and Spearman rank correlation test. Results: All implants reached to a strong primary stability with a mean 36.13 ± 2.47 and 35.47 ± 2.85 N/cm ITV. In the surgical stage, RFA values for SLA and modSLA implants were found to be 72.27 ± 3.17 and 71.6 ± 2.87, respectively. After 3 weeks of healing, mean BIC% (80.64 ± 13.89%) and RFA value (76.8 ± 1.14) of modSLA implants were significantly higher (P=0.0002) than that of SLA implants (64.39 ± 21.2 BIC% and 74.2 ± 4.76 RFA). However, no statistically significant difference between SLA and modSLA implants was recorded after 6 weeks of healing. Both implants revealed similar results in the RTT test (115.2 ± 4.14 and 117 ± 4.47 N/cm for SLA and modSLA implants, respectively). No correlation was found between RFA and BIC%. Conclusion: Within the limits of this pilot study, it can be concluded that modSLA implants achieve a higher bone contact and stability at earlier time points when compared with SLA implants. To cite this article:
Abdel‐Haq J, Karabuda CZ, Arιsan V, Mutlu Z, Kürkçü M. Osseointegration and stability of a modified sand‐blasted acid‐etched implant: an experimental pilot study in sheep.
Clin. Oral Impl. Res. 22 , 2011; 265–274.
doi: 10.1111/j.1600‐0501.2010.01990.x     

Bone regeneration at implants placed into extraction sockets of maxillary incisors in dogs

Aim: To compare the influence of autologous or deproteinized bovine bone mineral as grafting material on healing of buccal dehiscence defects at implants installed immediately into the maxillary second incisor extraction socket in dogs. Material and methods: In the maxillary second incisor sockets of 12 Labrador dogs, implants were installed immediately following tooth extraction. A standardized buccal defect was created and autologous bone particles or deproteinized bovine bone mineral were used to fill the defects. A collagen membrane was placed to cover the graft material, and the flaps were sutured to fully submerge the experimental areas. Six animals were sacrificed after 2 months, and six after 4 months of healing. Ground sections were obtained for histological evaluation. Results: After 2 months of healing, all implants were osseointegrated. All buccal dehiscence defects were completely filled after 2 months irrespective of the augmentation material (autologous bone or Bio‐Oss^®) applied. Bone‐to‐implant contact (BIC) on the denuded implant surfaces was within a normal range of 30–40%. However, the newly formed tissue at 2 months was partially resorbed (>50% of the area measurements) after 4 months. Conclusions: Applying either autologous bone or deproteinized bovine bone mineral to dehiscences at implants installed immediately into extraction sockets resulted in high degree of regeneration of the defects with satisfactory BIC on the denuded implant surface. To cite this article:
De Santis E, Botticelli D, Pantani F, Pereira FP, Beolchini M, Lang NP. Bone regeneration at implants placed into extraction sockets of maxillary incisors in dogs.
Clin. Oral Impl. Res. 22 , 2011; 430–437.     

Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs: part 1. Augmentation using bone graft substitutes and autogenous bone

Objectives: To assess the influence of two barrier membranes and two bone graft substitutes mixed with autogenous bone (AB) on staged guided bone regeneration and osseointegration of titanium implants in dogs. Materials and methods: Four saddle‐type defects each were prepared in the upper jaw of six fox hounds and randomly filled with a natural bone mineral (NBM)+AB and a biphasic calcium phosphate (SBC)+AB and allocated to either an in situ gelling polyethylene glycol (PEG) or a collagen membrane (CM). At 8 weeks, modSLA titanium implants were inserted and left to heal in a submerged position. At 8+2 weeks, dissected blocks were processed for histomorphometrical analysis (e.g., treated area [TA], bone‐to‐implant contact [BIC]). Results: The mean TA values (mm²) and BIC values (%) tended to be higher in the PEG groups(TA: NBM+AB [10.4 ± 2.5]; SBC+AB [10.4 ± 5.8]/BIC: NBM+AB [86.4 ± 20.1]; SBC+AB [80.1 ± 21.5]) when compared with the corresponding CM groups (TA: NBM+AB [9.7 ± 4.8]; SBC+AB [7.8 ± 4.3]/BIC: NBM+AB [71.3 ± 20.8]; SBC+AB [72.4 ± 20.3]). A significant difference was observed for the mean TA values in the SBC+AB groups. Conclusion: It was concluded that all augmentation procedures investigated supported bone regeneration and staged osseointegration of modSLA titanium implants. However, the application of PEG may be associated with increased TA values. To cite this article:
Schwarz F, Mihatovic I, Golubovic V, Hegewald A, Becker J. Influence of two barrier membranes on staged guided bone regeneration and osseointegration of titanium implants in dogs: part 1. Augmentation using bone graft substitutes and autogenous bone.
Clin. Oral Impl. Res. 23 , 2012; 83–89.
doi: 10.1111/j.1600‐0501.2011.02187.x     

Stability, marginal bone loss and survival of standard and modified sand-blasted, acid-etched implants in bilateral edentulous spaces: a prospective 15-month evaluation

Objectives: Chemical modification of the already proven sand‐blasted and acid‐etched (SLA) implant had increased its surface wettability and consequent early‐term osseointegration characteristics. The aim of this clinical trial was to compare the stability changes, success, survival, peri‐implant parameters and marginal bone loss (MBL) of the early‐loaded standard (SLA) and modified sand‐blasted, acid‐etched (modSLA) implants. Material and methods: A total of 96 SLA and modSLA implants were placed in a bi‐lateral, cross‐arch position to the jaws of 22 patients. Resonance frequency analysis (RFA) was used to measure the implant stability in the surgery and following healing after 1, 3 and 6 weeks. At the stage of loading, a panoramic X‐ray was obtained and RFA measurement was repeated for all implants. Implants were restored by metal–ceramic crowns and followed for 1 year to determine the success, survival rate, peri‐implant parameters and MBL. Results were compared by one‐ and two‐way ANOVA, log‐rank test and generalized linear mixed models (P<0.05). Results: One modSLA implant was lost after 3 weeks following the surgery yielding to a 100 and 97.91% success rate for SLA and modSLA implants, respectively (P=0.323). At the loading stage, modSLA implants showed significantly lower MBL (0.18 ± 0.05 mm) than SLA implants (0.22 ± 0.06 mm; P=0.002). In the loading stage, RFA value of the modSLA implants (60.42 ± 6.82) was significantly higher than the both implant types in the surgical stage (55.46 ± 8.29 and 56.68 ± 8.19), and following 1 (56.08 ± 7.01 and 55.60 ± 9.07) and 3 weeks of healing (55.94 ± 5.95 and 55.40 ± 6.50 for SLA and modSLA implants, respectively). Conclusions: modSLA implants demonstrated a better stability and a reduced MBL at the loading stage. Both SLA and modSLA implants demonstrated a favorable success and survival at the end of 15‐month follow‐up. To cite this article :
Karabuda ZC, Abdel‐Haq J. Arιsan V. Stability, marginal bone loss and survival of standard and modified sand‐blasted, acid‐etched implants in bilateral edentulous spaces: a prospective 15‐month evaluation.
Clin. Oral Impl. Res. 22 , 2011; 840–849
doi: 10.1111/j.1600‐0501.2010.02065.x     

Influence of a machined collar on crestal bone changes around titanium implants: a histometric study in the canine mandible

Background: It has been shown that peri‐implant crestal bone reactions are influenced by both a rough–smooth implant border in one‐piece, non‐submerged, as well as an interface (microgap [MG] between implant/abutment) in two‐piece butt‐joint, submerged and non‐submerged implants being placed at different levels in relation to the crest of the bone. According to standard surgical procedures, the rough–smooth implant border for implants with a smooth collar should be aligned with the crest of the bone exhibiting a smooth collar adjacent to peri‐implant soft tissues. No data, however, are available for implants exhibiting a sandblasted, large‐grit and acid‐etched (SLA) surface all the way to the top of a non‐submerged implant. Thus, the purpose of this study is to histometrically examine crestal bone changes around machined versus SLA‐surfaced implant collars in a side‐by‐side comparison. Methods: A total of 60 titanium implants (30 machined collars and 30 SLA collars) were randomly placed in edentulous mandibular areas of five foxhounds forming six different subgroups (implant subgroups A to F). The implants in subgroups A to C had a machined collar (control), whereas the implants in subgroups D to F were SLA‐treated all the way to the top (MG level; test). Furthermore, the MGs of the implants were placed at different levels in relation to the crest of the bone: the implants in subgroups A and E were 2 mm above the crest, in subgroups C and D 1 mm above, in subgroup B 3 mm above, and in subgroup F at the bone crest level. For all implants, abutment healing screws were connected the day of surgery. These caps were loosened and immediately retightened monthly. At 6 months, animals were sacrificed and non‐decalcified histology was analyzed by evaluating peri‐implant crestal bone levels. Results: For implants in subgroup A, the estimated mean crestal bone loss (± SD) was ?0.52 ± 0.40 mm; in subgroup B, +0.16 ± 0.40 mm (bone gain); in subgroup C, ?1.28 ± 0.21 mm; in subgroup D, ?0.43 ± 0.43 mm; in subgroup E, ?0.03 ± 0.48 mm; and in subgroup F, ?1.11 ± 0.27 mm. Mean bone loss for subgroup A was significantly greater than for subgroup E (P = 0.034) and bone loss for subgroup C was significantly greater than for subgroup D (P <0.001). Conclusions: Choosing a completely SLA‐surfaced non‐submerged implant can reduce the amount of peri‐implant crestal bone loss and reduce the distance from the MG to the first bone–implant contact around unloaded implants compared to implants with a machined collar. Furthermore, a slightly exposed SLA surface during implant placement does not seem to compromise the overall hard and soft tissue integration and, in some cases, results in coronal bone formation in this canine model.     

Bone apposition around two different sandblasted, large-grit and acid-etched implant surfaces at sites with coronal circumferential defects: an experimental study in dogs

Objective: The study was designed to evaluate bone apposition around SLA (sandblasted, large-grit and acid-etched) implants compared with modified SLA (modSLA) ones at sites with different sizes of circumferential gaps.
Material and methods: All mandibular premolars and first molars of six beagle dogs were extracted. After a healing period of 3 months, three 10-mm-long implants were inserted in each side of the mandible. One implant was inserted with a 0.5-mm and one with a 1-mm gap between the implants and bone around the coronal 5 mm of the implants. The third implant was inserted without a gap as a control. The dogs were sacrificed respectively at weeks 2, 4 and 8 after implant placement for histological and histomorphometric analyses.
Results: The histomorphometric results showed similar pattern of bone apposition for the two surfaces. At 2 and 4 weeks of healing, the percentage of newly formed bone-to-implant contact (BIC%), new bone fill (NBF%) and the distance between the most coronal position of BIC and the defect bottom (B–D) were significantly higher for modSLA ( P <0.05). At 8 weeks of healing, this difference was not significant ( P >0.05). With regard to the defect size, the histological analyses showed no significant differences between the two defect sizes at all time points ( P >0.05).
Conclusion: Significantly more bone apposition was found for the modSLA surface than for the SLA surface at early stage of healing, indicating that modSLA surface may enhance bone apposition in coronal circumferential defects at non-submerged implants. Gap size within 1 mm may not need any kind of regenerative procedures.     

Rehabilitation of irradiated patients with modified and conventional sandblasted acid-etched implants: preliminary results of a split-mouth study

Purpose: The aim of this study was to evaluate the success rate of chemically modified and conventional sandblasted acid‐etched surface (SLA) titanium implants in irradiated oral squamous cell carcinoma patients. Material and methods: 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 SLA and modSLA implants was performed bilaterally according to a split‐mouth design. All 102 implants (50 SLA, 52 modSLA) placed showed an unloaded healing time of 6 weeks in the mandible and 10 weeks in the maxilla. Mean crestal bone changes using standardized orthopantomographies and clinical parameters like pocket depths, mPII and mBI were evaluated. Results: Of 102 implants, 55 implants (27 SLA implants, 28 modSLA) were located in the maxilla and 47 implants (23 SLA, 24 modSLA) in the mandible. The average observation period was 14.4 months. The amount of bone loss at the implant shoulder of SLA implants was 0.4 mm mesial and 0.4 mm distal. The modSLA implants displayed a bone loss of mesial 0.3 mm and distal 0.3 mm. Two SLA implants were lost resulting in a success rate of 96%. The success rate of modSLA implants was 100%. Conclusion: Regarding the data found in this investigation, we can conclude that implants with chemically modified and conventional SLA titanium surface show high success rates in irradiated patients. SLA implants with or without a chemically modified surface regardless of the location can be restored with a high predictability of success at least in the short time range observed. To cite this article:
Heberer S, Kilic S, Hossamo J, Raguse J‐D, Nelson K. Rehabilitation of irradiated patients with modified and conventional sandblasted, acid‐etched implants: preliminary results of a split‐mouth study.
Clin. Oral Impl. Res. 22 , 2011; 546–551
doi: 10.1111/j.1600‐0501.2010.02050.x     

Bone apposition around two different sandblasted and acid-etched titanium implant surfaces: a histomorphometric study in canine mandibles

PURPOSE: The aim of this study was to evaluate bone apposition to a modified sandblasted and acid-etched (SLA) implant surface (modSLA) in the canine mandible as compared with the standard SLA surface. MATERIAL AND METHODS: In this experimental study, all mandibular premolars and first molars were extracted bilaterally in five foxhounds. After a healing period of 6 months, each side of the mandible received six randomly assigned dental implants alternating between the standard SLA and modSLA surface. The dogs were sacrificed at 2 weeks (n=2) or 4 weeks (n=3) after implant placement. Histologic and histomorphometric analyses were then performed for each implant. RESULTS: The microscopic healing patterns at weeks 2 and 4 for the two implant types with the standard SLA and modSLA surfaces showed similar qualitative findings. New bone tissue had already established direct contact with implant surfaces after 2 weeks of healing. The mean percentage of newly formed bone in contact with the implant (BIC) was significantly greater for modSLA (28.2+/-7.9%) than for SLA (22.2+/-7.3%) (P<0.05). This difference was no longer evident after 4 weeks. An increase in BIC for both implant surface types occurred from weeks 2 to 4. This increase was statistically significant when compared with SLA at 2 weeks (P<0.05), but not when compared with modSLA at 2 weeks. CONCLUSION: The data from the present study demonstrate significantly more bone apposition for the modSLA surface than the standard SLA surface after 2 weeks of healing. This increased bone apposition may allow a further reduction of the healing period following implant placement for patients undergoing early loading procedures.     

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     

Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs

Purpose: The aim of the present study was to evaluate bone remodeling and bone‐to‐implant contact (BIC) after immediate placement at different levels in relation to the crestal bone of Beagle dogs. Materials and methods: The mandibular bilateral second, third and fourth premolars of six Beagle dogs were extracted and six implants were immediately placed in the hemi‐arches of each dog. Randomly, three cylindrical and three tapered implants were inserted crestally (control group) and 2 mm subcrestally (experimental group). Both groups were treated with a minimal mucoperiosteal flap elevation approach. A gap from the buccal cortical wall to the implant was always left. Three dogs were allowed a 4‐week submerged healing period and the other three an 8‐week submerged healing period. The animals were sacrificed and biopsies were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out in order to compare buccal and lingual bone height loss, and BIC between the two groups. Results: All implants osseointegrated clinically and histologically. Healing patterns examined microscopically at 4 and 8 weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. The distance from the top of the implant collar to the first BIC in the lingual crest (A–Lc) showed a significant difference (P=0.0313): 1.91 ± 0.2 mm in the control group and 1.08 ± 0.2 mm in the experimental group. There was less bone resorption in subcrestal implants than crestal implants. The mean percentage of newly formed BIC was greater with the cylindrical implant design (46.06 ± 4.09%) than with the tapered design (32.64 ± 3.72%). Conclusion: These findings suggest that apical positioning of the top of the implant does not jeopardize bone crest and peri‐implant tissue remodeling. However, less resorption of the Lc may be expected when implants are placed 2 mm subcrestally. To cite this article:
Negri B, Calvo‐Guirado JL, Pardo‐Zamora G, Ramírez‐Fernández MP, Delgado‐Ruíz RA, Muñoz‐Guzón F. Peri‐implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs.
Clin. Oral Impl. Res. 23 , 2012; 228–235.
doi: 10.1111/j.1600‐0501.2011.02158.x     

Immunohistochemical characterization of guided bone regeneration at a dehiscence-type defect using different barrier membranes: an experimental study in dogs

Objectives: The aim of the present study was to evaluate immunohistochemically the pattern of guided bone regeneration (GBR) using different types of barrier membranes. Material and methods: Standardized buccal dehiscence defects were surgically created following implant bed preparation in 12 beagle dogs. Defects were randomly assigned to six different GBR procedures: a collagen‐coated bone grafting material (BOC) in combination with either a native, three cross‐linked, a titanium‐reinforced collagen membrane, or expanded polytetrafluorethylene (ePTFE), or BOC alone. After 1, 2, 4, 6, 9, and 12 weeks of submerged healing, dissected blocks were processed for immunohistochemical (osteocalcin – OC, transglutaminase II – angiogenesis) and histomorphometrical analysis [e.g., bone‐to‐implant contact (BIC), area of new bone fill (BF)]. Results: In general, angiogenesis, OC antigen reactivity, and new bone formation mainly arose from open bone marrow spaces at the bottom of the defect and invaded the dehiscence areas along the implant surface and BOC. At 4 weeks, membranes supporting an early transmembraneous angiogenesis also exhibited some localized peripheral areas of new bone formation. However, significantly increasing BIC and BF values over time were observed in all groups. Membrane exposure after 10–12 weeks was associated with a loss of the supporting alveolar bone in the ePTFE group. Conclusion: Within the limits of the present study, it was concluded that (i) angiogenesis plays a crucial role in GBR and (ii) all membranes investigated supported bone regeneration on an equivalent level.     

Vertical Osteoconductive Characteristics of Titanium Implants with Calcium‐Phosphate‐Coated Surfaces – A Pilot Study in Rabbits

Introduction: Osteoconductive characteristics of different implant surface coatings are in the focus of current interest. The aim of the present study was to compare the vertical osteoconductivity at the implant shoulder of supracrestal inserted calcium‐phosphate coated implants (SLA‐CaP) with conventional sand‐blasted/acid‐etched (SLA) implants in a rabbit model. Materials and Methods: SLA‐CaP and SLA implants were inserted bilaterally in the mandible of four rabbits in a split‐mouth design. The implants were placed 2 mm supracrestal. After 3 weeks, at the left and right implant shoulder, the percentage of linear bone fill (PLF) as well as bone‐implant contact (BIC‐D) were determined. Results: After 3 weeks, newly formed woven bone could be found at the shoulder of the most of both surface‐treated implants (75%). PLF was significantly higher in SLA‐CaP implants (11.2% vs. 46.5%; n = 8, p = .008). BIC‐D was significantly increased in the SLA‐CaP implants (13.0% vs. 71.4%; n = 8, p < .001) as well. Conclusion: The results of this study show for the first time that calcium‐phosphate coated surfaces on supracrestal inserted implants have vertical osteoconductive characteristics and increase the bone‐implant contact at the implant shoulder significantly in a rabbit model. In clinical long‐term settings, these implants may contribute to a better vertical bone height.     

Tissue integration of a new titanium-zirconium dental implant: a comparative histologic and radiographic study in the canine

Background: This study evaluates a newly developed titanium–zirconium implant (TiZr), comparing it to a commercially available pure titanium (Ti) implant subjected to the same surface treatment. Methods: In nine dogs, 12 implants (six TiZr and six Ti) were randomly placed in the mandible with the implant shoulder at the bone crest and subjected to submerged healing. Standardized radiographs were taken after implantation, and at the sacrifice of 2 weeks (three dogs), 4 weeks (three dogs), and 8 weeks (three dogs). Histologic and histomorphometric measurements were performed on non‐decalcified histologic sections. The main outcome measures included the first bone–implant contact (fBIC) and BIC over time. For statistical analysis, Wilcoxon signed‐rank test and mixed model regressions were applied. Results: From baseline to 8 weeks, a mean bone loss of 0.09 ± 0.33 mm for TiZr and a gain of 0.02 ± 0.33 mm for Ti were calculated radiographically. The number of implants with the fBIC coronal to the reference point (implant shoulder) gradually increased over time, reaching 39% of all TiZr implants and 50% of all Ti implants at 8 weeks. The mean fBIC values for Ti and TiZr were 0.29 ± 0.42 mm and 0.26 ± 0.32 mm (2 weeks), ?0.01 ± 0.20 mm and 0.10 ± 0.28 mm (4 weeks), and ?0.06 ± 0.22 mm and 0.08 ± 0.30 mm (8 weeks), respectively. The mean BIC values peaked at 86.9% ± 6.8% (8 weeks) for TiZr and at 83.4% ± 5.9% (4 weeks) for Ti. No statistically significant differences were observed at any time point. Conclusion: TiZr and Ti bone level implants with chemically‐modified, sandblasted, and acid‐etched surfaces performed similarly in regards to osseointegration in this unloaded canine study.     

Effect of implant surface properties on peri-implant bone healing: a histological and histomorphometric study in dogs

Aim: The present study aimed to evaluate and compare two types of implants, i.e. grit‐blasted and acid‐etched implants (SLActive^®) with nano‐meter‐scale hydroxyapatite surface‐modified implants (NanoTite^?). Material and methods: For histological and histomorphometrical evaluation, 22 SLActive^® and 22 Nanotite^? implants were inserted in eleven Beagle dogs. The animals were divided into three groups of healing (A: 2 weeks; B: 4 weeks and C: 8 weeks). Two, 4 and 8 weeks after implantation, the animals were sacrificed and bone‐to‐implant contact (BIC %), first implant–bone contact (1st BIC) as well as amount of bone (BV) were assessed. Results: For SLActive^® and Nanotite^? implants, BIC% increased significantly over time. No statistically significant differences in BIC% were found between SLActive^® and Nanotite^? at all the respective implantation times. Moreover, for the different healing periods, no significant differences for BV between SLActive^® and Nanotite^? implants were found. Conclusions: The present study showed that SLActive^® and NanoTite^? implants induce a similar bone response after implantation for 2, 4 and 8 weeks in a non‐submerged position in the mandible of dogs. To cite this article:
Al‐Hamdan K, Al‐Moaber SH, Junker R, Jansen JA. Effect of implant surface properties on peri‐implant bone healing: a histological and histomorphometric study in dogs.
Clin. Oral Impl. Res. 22 , 2011; 399–405.     

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     

The effect of SLActive surface in guided bone formation in osteoporotic-like conditions

Objectives: The aim of the study was to evaluate new bone formation under etched titanium (SLA) and modified‐etched hydrophilic titanium (modSLA) domes placed on the calvarium of healthy, osteoporotic and osteoporotic treated with bisphosphonates rabbits. Methods: Experimental osteoporosis was induced by ovariectomy (OV) and calcium‐deficient diet in 24 New Zealand female rabbits. Twelve OV rabbits were treated with weekly dozes of alendronate (Fosamax^®) (B) while 12 OV rabbits received no treatment (O). Another 12 rabbits were sham operated and used as healthy controls (C). At 6 weeks following OV, one modSLA and one SLA titanium dome were placed in the parietal bones of each rabbit. The animals were sacrificed at 30 and 120 days following the dome placement. Various histomorphometric measurements were performed in the most central of the undecalcified sections produced. Results: After 30 days of healing, in the C group, the total bone (TB) area was 37.6% and 37.0% under the modSLA and SLA domes, respectively. In the O group, the TB was 35.7% and 24.8%. In the B group, TB was 37.0% and 32.1%, respectively. After 120 days of healing, in the C group TB was 40.1% and 36.4%, respectively. In the O group, TB was 29.6% and 27.9%, respectively. In the B group, TB was 49.7% and 42.5%, respectively. Hierarchical analysis of variance showed that the type of titanium dome significantly influenced new bone and the amount of new bone being in contact with inner surface of the dome (BIC) independently of the observation period and group (P<0.05). The administration of bisphosphonates influenced the BIC (P<0.05). Conclusion: The use of modSLA surface may promote bone healing and osseointegration in osteoporotic rabbits, whereas administration of bisphosphonates may compromise the osseointegration of the newly formed bone at the early healing period. To cite this article:
Mardas N, Schwarz F, Petrie A, Hakimi A‐R, Donos N. The effect of SLActive surface in guided bone formation in osteoporotic‐like conditions.
Clin. Oral Impl. Res. 22 , 2011; 406–415.
doi: 10.1111/j.1600‐0501.2010.02094.x     

Histological and immunohistochemical analysis of initial and early osseous integration at chemically modified and conventional SLA titanium implants: preliminary results of a pilot study in dogs

OBJECTIVES: The aim of the present pilot study was to investigate initial and early tissue reactions to modified (mod) and conventional sand-blasted, large grit and acid-etched (SLA) titanium implants. MATERIAL AND METHODS: Implantation of modSLA and SLA implants was performed bilaterally in both the mandible and maxilla of dogs. The animals were sacrificed after a healing period of 1, 4, 7 and 14 days, respectively. Peri-implant tissue reactions were assessed in non-decalcified tissue sections using conventional histology (Toluidine blue-TB and Masson Goldner Trichrome stain-MG) and immunohistochemistry using monoclonal antibodies to transglutaminase II (TG) (angiogenesis) and osteocalcin (OC). Bone density (BD) and bone to implant contact (BIC) were assessed histomorphometrically. RESULTS: Day 1 revealed an early TG antigen reactivity in the provisional fibrin matrix adjacent to both implant surfaces. Day 4 was characterized by the formation of a collagen-rich connective tissue (MG), which revealed the first signs of OC synthesis adjacent to modSLA surfaces. Immunohistochemical staining for TG revealed a direct correlation between angiogenesis and new bone formation, which was clearly identifiable after 7 days by means of increasing BD, BIC and OC values. After 14 days, modSLA surfaces seemed to be surrounded by a firmly attached mature, parallel-fibered woven bone. CONCLUSIONS: Within the limits of the present study, it might be concluded that the combination of immunohistochemical and conventional histological stainings in non-decalcified tissue sections is a valuable technique to evaluate the initial and early stages of wound healing around endosseous titanium implants.