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.     

Histological and immunohistochemical analysis of initial and early subepithelial connective tissue attachment at chemically modified and conventional SLA®titanium implants. A pilot study in dogs

The aim of the present pilot study was to histologically/immunohistochemically investigate initial and early subepithelial connective tissue attachment at transmucosal parts of modified (mod) and conventional sandblasted, large grit and acid-etched (SLA) titanium implants. Implantation of modSLA and SLA implants was performed bilaterally in both the mandible and maxilla of four beagle dogs. The implants were submerged to prevent bacterial contamination. The animals were killed after 1, 4, 7 and 14 days. Peri-implant tissue reactions were assessed histologically (Masson Goldner Trichrome stain-MG) and immunohistochemically (IH) using monoclonal antibodies to fibronectin (FN) and proliferating cell nuclear antigen (PCNA). The surgical procedure of implant submerging resulted in the formation of an artificial gap in the transmucosal area of both types of implants. After 14 days of healing, MG stain revealed the formation of well-organized collagen fibres and numerous blood vessels in a newly formed loose connective tissue zone adjacent to modSLA. While some fibres were oriented in a parallel direction, others have started to extend and attach partially perpendicular to the implant surface. In contrast, SLA implants appeared to be clearly separated by a dense connective tissue zone with parallel-running collagen fibres and rare blood vessel formation. First signs of a positive FN and PCNA staining adjacent to both implant surfaces were observed at day 4. Within the limits of a pilot study, it might be concluded that modSLA titanium surfaces might possess the potential to promote subepithelial connective tissue attachment at the transmucosal part of the implant.     

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.     

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.     

Effects of surface hydrophilicity and microtopography on early stages of soft and hard tissue integration at non-submerged titanium implants: an immunohistochemical study in dogs

BACKGROUND: The aim of the present study was to investigate the effects of surface hydrophilicity and microtopography on soft and hard tissue integration at non-submerged titanium implants. METHODS: Implantation of conventional sand-blasted large grit and acid-etched (SLA) and chemically modified SLA (modSLA) titanium implants with differently structured transmucosal surfaces (SLA implants: machined [M-SLA] or SLA [SLA-SLA]; modSLA implants: mod acid-etched [modA] [modA-modSLA] or modSLA [modSLA-modSLA]) was performed bilaterally in the upper and lower jaws of 15 beagle dogs. The animals were sacrificed after 1, 4, 7, 14, or 28 days. Tissue reactions were assessed histomorphometrically and immunohistochemically using monoclonal antibodies to transglutaminase II (angiogenesis) and osteocalcin. RESULTS: Although the junctional epithelium commonly was separated from M-SLA and SLA-SLA implants by a gap, the epithelial cells appeared to be in close contact with modA-modSLA surfaces after 14 days of healing. Moreover, modA-modSLA and modSLA-modSLA groups showed a well-vascularized subepithelial connective tissue exhibiting collagen fibers that started to extend and attach partially perpendicular to the implant surface. The highest and statistically significant mean bone-to-implant contact areas were observed in the modA-modSLA and modSLA-modSLA groups at days 7, 14, and 28. CONCLUSION: Within the limits of this study, it may be concluded that soft and hard tissue integration was influenced mainly by surface hydrophilicity rather than by microtopography.     

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.     

Stability change of chemically modified sandblasted/acid-etched titanium palatal implants. A randomized-controlled clinical trial

Aim: The aim of this randomized-controlled clinical study was to examine stability changes of palatal implants with chemically modified sandblasted/acid-etched (modSLA) titanium surface compared with a standard SLA surface, during the early stages of bone healing.
Materials and methods: Forty adult volunteers were recruited and randomly assigned to the test group (modSLA surface) and to the control group (SLA surface). The test and control implants had the same microscopic and macroscopic topography, but differed in surface chemistry. To document implant stability changes resonance frequency analysis (RFA) was performed at implant insertion, at 7, 14, 21, 28, 35, 42, 49, 56, 70 and 84 days thereafter. RFA values were expressed as an implant stability quotient (ISQ).
Results: Immediately after implant installation, the ISQ values for both surfaces tested were not significantly different and yielded mean values of 73.8±5 for the control and 72.7±3.9 for the test surface. In the first 2 weeks after implant installation, both groups showed only small changes and thereafter a decreasing trend in the mean ISQ levels. In the test group, after 28 days a tendency towards increasing ISQ values was observed and 42 days after surgery the ISQ values corresponded to those after implant insertion. For the SLA-control group, the trend changed after 35 days and yielded ISQ values corresponding to the baseline after 63 days. After 12 weeks of observation, the test surface yielded significantly higher stability values of 77.8±1.9 compared with the control implants of 74.5±3.9, respectively.
Conclusion: The results support the potential for chemical modification of the SLA surface to positively influence the biologic process of osseointegration and to decrease the healing time.     

Interactions between endothelial progenitor cells (EPC) and titanium implant surfaces

Objectives

Endothelial cells play an important role in peri-implant angiogenesis during early bone formation. Therefore, interactions between endothelial progenitor cells (EPCs) and titanium dental implant surfaces are of crucial interest. The aim of our in vitro study was to investigate the reactions of EPCs in contact with different commercially available implant surfaces.

Materials and methods

EPCs from buffy coats were isolated by Ficoll density gradient separation. After cell differentiation, EPC were cultured for a period of 7 days on different titanium surfaces. The test surfaces varied in roughness and hydrophilicity: acid-etched (A), sand-blasted-blasted and acid-etched (SLA), hydrophilic A (modA), and hydrophilic SLA (modSLA). Plastic and fibronectin-coated plastic surfaces served as controls. Cell numbers and morphology were analyzed by confocal laser scanning microscopy. Secretion of vascular endothelial growth factor (VEGF)-A was measured by enzyme-linked immunosorbent assay and expressions of iNOS and eNOS were investigated by real-time polymerase chain reaction.

Results

Cell numbers were higher in the control groups compared to the cells of titanium surfaces. Initially, hydrophilic titanium surfaces (modA and modSLA) showed lower cell numbers than hydrophobic surfaces (A and SLA). After 7 days smoother surfaces (A and modA) showed increased cell numbers compared to rougher surfaces (SLA and modSLA). Cell morphology of A, modA, and control surfaces was characterized by a multitude of pseudopodia and planar cell soma architecture. SLA and modSLA promoted small and plump cell soma with little quantity of pseudopodia. The lowest VEGF level was measured on A, the highest on modSLA. The highest eNOS and iNOS expressions were found on modA surfaces.

Conclusions

The results of this study demonstrate that biological behaviors of EPCs can be influenced by different surfaces. The modSLA surface promotes an undifferentiated phenotype of EPCs that has the ability to secrete growth factors in great quantities.

Clinical relevance

In correlation with recent clinical studies these results underline the hypothesis that EPC could promote and increase neovascularization by secreting paracrine factors which support osseointegration of dental implants.     

Histomorphometric evaluation of six dental implant surfaces after early loading in augmented human sinuses

This study investigated the bone-to-implant contact (BIC) and osteoconductive capacity (OC) of 6 different implant surfaces after early loading in humans. Two implants with different surfaces were placed side-by-side in the grafted (n= 5) and nongrafted (n = 1) sinuses of 3 volunteers. Single-tooth restorations were delivered 60 days later. After 6 months of full occlusal loading, implants were retrieved in block sections for histomorphometric analysis. One implant (acid etched) placed in grafted bone failed when loaded. There were no other complications. In grafted bone, the microtextured surface achieved the highest BIC value (94.08%), followed by the oxidized (77.32%), hydroxyapatite (HA) (74.51%), sandblasted and acid-etched (51.85%), and titanium plasma-sprayed (TPS) (41.48%) surfaces. In native bone, the acid-etched surface achieved a higher BIC value (69.03%) than the HA surface (59.03%). The highest OC value in grafted bone was exhibited by the microtextured surface (34.31%), followed by the HA (28.62%), sandblasted and acid-etched (25.08%), oxidized (17.55%), and TPS (-20.47%) surfaces. The HA surface exhibited a higher OC value (30.39%) in native bone compared with the acid-etched surface (24.0%). As a whole, highest BIC and OC values were exhibited by the microtextured surface, and lowest values were exhibited by the TPS surface. All other surfaces demonstrated excellent BIC (>50%) but varied in OC (range = 17.55%-28.62%). These findings are tempered by the limited scope and sample size of the study and should be considered preliminary. More research is needed to determine the impact of implant surface texture on BIC and OC.     

Effects of Simvastatin on bone healing around titanium implants in osteoporotic rats

Objectives: Osteoporosis is known to impair the process of implant osseointegration. The recent discovery that statins (HMG‐CoA reductase inhibitors) act as bone anabolic agents suggests that statins can be used as potential agents in the treatment of osteoporosis. Therefore, we hypothesized that statins will promote osteogenesis around titanium implants in subjects with osteoporosis. Material and methods: Fifty‐four female Sprague Dawley rats, aged 3 months old, were randomly divided into three groups: Sham‐operated group (SHAM; n=18), ovariectomized group (OVX; n=18), and ovariectomized with Simvastatin treatment group (OVX+SIM; n=18). Fifty‐six days after being ovariectomized (OVX), screw‐shaped titanium implants were inserted into the tibiae. Simvastatin was administered orally at 5 mg/kg each day after the placement of the implant in the OVX+SIM group. The animals were sacrificed at either 28 or 84 days after implantation and the undecalcified tissue sections were obtained. Bone‐to‐implant contact (BIC) and bone area (BA) within the limits of implant threads were measured around the cortical (zone A) and cancellous (zone B) bone regions. Furthermore, bone density (BD) of zone B in a 500 μm wide zone lateral to the implants was also measured. Results: There were no significant differences in BIC and BA measurements in zone A in any of the three groups at either 28 or 84 days after implantation (P>0.05). By contrast, in zone B, significant differences in the measurement of BIC, BA, and BD were observed at 28 and 84 days between all three groups. Bone healing decreased with lower BIC, BA, and BD around implant in OVX group compared with other two groups, and Simvastatin reversed the negative effect of OVX on bone healing around implants with the improvement of BIC, BA, and BD in zone B. Conclusion: Osteoporosis can significantly influence bone healing in the cancellous bone around titanium implants and Simvastatin was shown to significantly improve the osseointegration of pure titanium implants in osteoporotic rats.     

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     

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     

Histometric evaluation of bone around titanium implants with different surface treatments in rats exposed to cigarette smoke inhalation

Objectives: There is a lack of histological information about the influence of cigarette smoke on bone around surface-treated implants. The aim of the present study was to test the influence of titanium surface treatment on osseointegration in animals that were exposed to intermittent cigarette smoke inhalation.
Material and methods: Twenty-two male Wistar rats were used. One tibia, chosen at random, received a machined titanium implant (MI) while the other received an aluminum oxide-blasted surface implant (ABI). The animals were randomly assigned to one of the following groups: Group 1 – control ( n =11) and Group 2 – intermittent cigarette smoke inhalation ( n =11). Sixty days after surgery, the animals were sacrificed. The degree of bone-to-implant contact (BIC), bone filling (BF) within the limits of the threads of the implants and bone density (proportion of mineralized bone in a 500-μm-wide zone lateral to the implant – BD) were measured in the cortical (zone A) and cancellous bone (zone B) areas.
Results: Data analysis showed significant differences when comparing the groups and implant surfaces in both zones for BIC (two-way ANOVA – P <0.05). The two groups presented higher BIC mean values for ABI, when compared with MI ( P <0.05). In group 2, cigarette smoke inhalation negatively affected BF in both zones ( P <0.05). Group 2 presented a significantly decreased BD in both zones ( P <0.05). No statistically significant differences were observed between surfaces in any of the groups for BD.
Conclusion: Within the limits of the present study, it can be concluded that the aluminum oxide blast surface treatment may increase the degree of BIC but cannot overcome the detrimental effect of tobacco smoke on bone around titanium implants.     

Effect of cigarette smoke inhalation and estrogen deficiency on bone healing around titanium implants: a histometric study in rats

BACKGROUND: It has been shown that cigarette smoke inhalation (CSI) and estrogen deficiency (OVX) may affect bone quality around titanium implants; however, their association has not been evaluated. Therefore, this study aimed to verify the effects of CSI associated with OVX on bone healing around titanium implants. METHODS: The tibia surface of 45 female Wistar rats was surgically exposed, and screw-shaped titanium implants were placed. The animals were randomly assigned to OVX (ovariectomized rats; n = 15), SHAM (sham-operated rats; n = 15), and CSI + OVX (4 months of intermittent cigarette smoke inhalation, starting 2 months before implant placement in ovariectomized rats; n = 15). The implants were placed at the time of OVX or SHAM surgery. After 60 days, the animals were sacrificed and undecalcified sections obtained. The percentages of mineralized tissue (bone density [BD]) in a 500-microm-wide zone lateral to the implant, bone filling (BF) within the limits of the threads, and bone-to-implant contact (BIC) were measured in cortical (zone A) and cancellous (zone B) bone. RESULTS: In zone A, the CSI + OVX group showed a significant difference regarding BIC and BD (P <0.05) compared to the other groups. In zone B, data analysis showed that the CSI + OVX group presented the lowest percentage of BD and BIC, followed by the OVX and SHAM groups, respectively (P <0.05). CONCLUSION: Within the limits of the present study, it can be concluded that cigarette smoke inhalation amplified the deleterious effects of estrogen deficiency, affecting both preexisting and newly formed bone in the cortical and cancellous bone around titanium implants.     

Age-related and surgically induced estrogen deficiencies may differently affect bone around titanium implants in rats

BACKGROUND: Valuable information has been obtained using the ovariectomy model; however, clinical studies have indicated that such a model may not be appropriate to parallel with the postmenopausal condition and titanium implants. Thus, this study aimed to comparatively evaluate, by histometric analysis, the influence of age-related (ARED) and surgically induced (OVX) estrogen deficiencies on bone around titanium implants inserted in rats. METHODS: Single screw-shaped titanium implants were placed in rat tibiae and animals were then assigned to one of the following groups: SHAM (N = 15): bilateral sham ovariectomies in 90-day-old rats, 21 days before implant placement; OVX (N = 15): bilateral ovariectomies in 90-day-old rats, 21 days before implant placement; and ARED (N = 15): implant placement in reproductive aged rats (22 months old). After 60 days, the animals were sacrificed and undecalcified sections obtained. Bone-to-implant contact (BIC) and bone area (BA) within the limits of implant threads and bone density (BD) in a 500 microm-wide zone lateral to the implant were obtained and arranged for cortical (zone A) and cancellous (zone B) bone regions. RESULTS: For zone A, intergroup analysis showed no significant differences regarding BIC and BA (P >0.05). In contrast, ARED negatively influenced BD around the implants (P <0.05). In zone B, OVX negatively affected BIC and BA (P <0.05), and both ARED and OVX groups demonstrated lower BD than the SHAM group (P <0.05). CONCLUSION: Within the limits of this study, it can be concluded that ARED mainly affects preexisting bone while OVX more significantly affects both newly formed and preexisting bone.     

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     

Enhanced bone apposition to a chemically modified SLA titanium surface

Increased surface roughness of dental implants has demonstrated greater bone apposition; however, the effect of modifying surface chemistry remains unknown. In the present study, we evaluated bone apposition to a modified sandblasted/acid-etched (modSLA) titanium surface, as compared with a standard SLA surface, during early stages of bone regeneration. Experimental implants were placed in miniature pigs, creating 2 circular bone defects. Test and control implants had the same topography, but differed in surface chemistry. We created the test surface by submerging the implant in an isotonic NaCl solution following acid-etching to avoid contamination with molecules from the atmosphere. Test implants demonstrated a significantly greater mean percentage of bone-implant contact as compared with controls at 2 (49.30 vs. 29.42%; p = 0.017) and 4 wks (81.91 vs. 66.57%; p = 0.011) of healing. At 8 wks, similar results were observed. It is concluded that the modSLA surface promoted enhanced bone apposition during early stages of bone regeneration.     

Enhanced bone apposition around biofunctionalized sandblasted and acid-etched titanium implant surfaces. A histomorphometric study in miniature pigs

Microrough titanium (Ti) surfaces of dental implants have demonstrated more rapid and greater bone apposition when compared with machined Ti surfaces. However, further enhancement of osteoblastic activity and bone apposition by bio-functionalizing the implant surface with a monomolecular adsorbed layer of a co-polymer - i.e., poly(L-lysine)-graft-poly(ethylene glycol) (PLL-g-PEG) and its derivatives (PLL-g-PEG/PEG-peptide) - has never been investigated. The aim of the present study was to examine early bone apposition to a modified sandblasted and acid-etched (SLA) surface coated with an Arg-Gly-Asp (RGD)-peptide-modified polymer (PLL-g-PEG/PEG-RGD) in the maxillae of miniature pigs, and to compare it with the standard SLA surface. Test and control implants had the same microrough topography (SLA), but differed in their surface chemistry (polymer coatings). The following surfaces were examined histomorphometrically: (i) control - SLA without coating; (ii) (PLL-g-PEG); (iii) (PLL-g-PEG/PEG-RDG) (RDG, Arg-Asp-Gly); and (iv) (PLL-g-PEG/PEG-RGD). At 2 weeks, RGD-coated implants demonstrated significantly higher percentages of bone-to-implant contact as compared with controls (61.68% vs. 43.62%; P < 0.001). It can be concluded that the (PLL-g-PEG/PEG-RGD) coatings may promote enhanced bone apposition during the early stages of bone regeneration.     

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     

Chemisch modifizierte, ultra-hydrophile Titanimplantatoberflächen

Recently, a chemically modified ultra-hydrophilic sand-blasted, large grit and acid-etched (modSLA) titanium surface has been introduced in order to enhance bone apposition. Indeed, preliminary preclinical and clinical data have indicated that modSLA implants may enhance bone apposition during early stages of wound healing. These positive effects on bone regeneration might be probably mainly due to the hydrophilic surface properties noted for modSLA which ensured a stabilization of the blood clot. The aim of the present review article is to evaluate, based on the currently available evidence, the potential impact of modSLA surfaces for implant dentistry.