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.     

Immediate implants at fresh extraction sockets: bone healing in four different implant systems

Objectives: To describe the differences in bone healing, when placing four different implant systems in fresh extraction sockets.
Material and Methods: Eight beagle dogs received implants randomly installed into the distal socket of three P3 and four P4. Four-implant systems were evaluated. Each animal provided four test implant sites. All animals were sacrificed at 6 weeks after implant placement, providing specimens for histo-morphometric analysis of bone to implant contact (BIC), bone area, new bone formation, as well as histometric measurements of the ridge alterations.
Results: No statistically significant difference was observed among the four-implant systems. The mean BIC % ranged between 58.5% and 72.1%. Bone modelling of the buccal plate was marked and amounted approximately to 2.5 mm, independently of the system used.
Conclusion: This study failed to demonstrate differences in the healing pattern after 6 weeks when placing four different implant systems in fresh extraction sockets. In spite of achieving predictable osteointegration with the four implants studied, the occurrence of buccal bone resorption may limit the use of this surgical approach.     

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.     

Is insertion torque correlated to bone–implant contact percentage in the early healing period? A histological and histomorphometrical evaluation of 17 human‐retrieved dental implants

Objective: A precise and scientifically established method for the evaluation of the bone quality/primary stability is the measure of the insertion torque (IT). The aim of this study was a comparison between the IT values and the bone–implant contact percentage (BIC) of human implants retrieved after a 4/8-week healing period.
Materials: Seventeen implants, all with a sandblasted and acid-etched surface, were evaluated in the present study.
Methods: The implants had been retrieved for different causes, after 4/8 weeks, with a 5 mm trephine bur, and immersed in 10% buffered formalin to be processed for histology.
Results: A not statistically significant correlation was found between IT and BIC ( P ≤0.892).
Conclusions: In the present study on human-retrieved implants, no statistically significant correlation was found between the IT values and BIC. These results could be due to a lack of relationship between bone structure and IT, or to the fact that primary stability may not only be influenced by bone volumetrical density and/or bone trabecular connectivity but also by the thickness and density of the cortical layer. Moreover, the present knowledge of the bone microstructure is not enough to explain the relationship of bone quality and primary implant stability.     

Increased bone formation around coated implants

Aim: We hypothesized that coating threaded, sandblasted acid-etched titanium implants with collagen and chondroitin sulphate (CS) increases bone formation and implant stability, compared with uncoated controls.
Materials and Methods: Three different implant surface conditions were applied: (1) sandblasted acid-etched (control), (2) collagen/chondroitin sulphate (low-dose – CS1), (3) collagen/chondroitin sulphate (high-dose – CS2). Sixty 9.5 mm experimental implants were placed in the mandible of 20 minipigs. Bone–implant contact (BIC) and relative peri-implant bone-volume density (rBVD – relation to bone-volume density of the host bone) were assessed after 1 and 2 months of submerged healing. Implant stability was measured by resonance frequency analysis (RFA).
Results: After 1 month, coated implants had significantly more BIC compared with controls (CS1: 68%, p <0.0001, CS2: 63%, p =0.009, control: 52%). The rBVD was lower for all surface conditions, compared with the hostbone. After 2 months, BIC increased for all surfaces. No significant differences were measured (CS1: 71%, p =0.016, CS2: 68%, p =0.67, control: 63%). The rBVD was increased for coated implants. RFA values were 71–77 at implantation, 67–73 after 1 month and 74–75 after 2 months. Differences in rBVD and RFA were not statistically significant.
Conclusions: Data analysis suggests that collagen/CS has a positive influence on bone formation after 1 month of endosseous healing.     

Primary loading of palatal implants for orthodontic anchorage--a pilot animal study.

OBJECTIVES: This study aimed at evaluating the clinical performance and osseointegration of short orthodontic implants immediately loaded with orthodontic forces. MATERIAL AND METHODS: The investigation was designed as an experimental animal study. Eight palatal implants of the Ortho-system were immediately loaded with 100 cN after palatal insertion in 4 female German shepherd dogs. Xylene orange and calcein green were used for polychrome sequential labelling. Histological preparation utilized the cutting and grinding technique. Outcome variables were clinical implant success, histological osseointegration and bone-to-implant contact rates. RESULTS: All (8/8) implants were clinically successful and stable when the animals were sacrificed. One implant showed fibrous encapsulation and was histologically classified as "failed" for "osseointegration". Upon morphometrical analysis, bone to implant contact rates for newly formed or remodelled bone were 19% at 4 weeks and 26% at 6 months. The fluorochrome labelling indicated substantial mineral apposition on the surface of the implants at the end of the first and the second postoperative months. CONCLUSION: This study revealed borderline reliability of osseointegration for immediately loaded palatal implants but reasonable bone formation at the 4th postoperative week. Thus, two clinical concepts are both supported: early orthodontic loading after 4 weeks as well as improvement of primary stability to provide a biomechanical basis for immediate orthodontic loading.     

A study of the bone healing kinetics of plateau versus screw root design titanium dental implants

Objective: This study was designed to compare the bone healing process around plateau root from (PRF) and screw root from (SRF) titanium dental implants over the immediate 12 week healing period post implant placement.
Material and methods: 32PRF and 32SRF implants were placed in 8 beagle dogs at 12, 8, 5 and 3 weeks prior to enthanisation using a bilaterally balanced distribution. Undecalcified ground sections were prepared from the biopsies taken and histometric measurements of bone implant contact (BIC) and bone area fraction occupancy (BAFO) were made on the middle 5 mm portion of each 8 mm implant root length.
Results: The analysis showed that although measurements of bone to implant contact (BIC) and bone area fraction occupancy (BAFO) tended to be greater for the SRF implants at all four time points, the differences in measurements between implant types did not reach statistical significance ( P =0.07, P =0.06). The effect of time on BIC and BAFO was found to be strongly significant for both implant types thus indicating a statistically significant increase in BIC and BAFO overall with time ( P =0.004, P =0.002). Furthermore, both PRF and SRF implants behaved similarly over time with measurements of BIC and BAFO progressing in parallel. Histomorphologic analysis of these sections demonstrated the prominent role of woven bone (callus) in the bone healing process around PRF implants.
Conclusion: The results can be interpreted to indicate a comparable development of secondary stability for both PRF and SRF implant designs. However, as these parameters reflect the structural connection between implant and bone and not the functional properties of the bone to implant interface, they cannot be regarded as comprehensive measures of osseointegration. This particularly relevant given the reduced load bearing capacity of woven bone.     

Osseointegration of zirconia and titanium dental implants: a histological and histomorphometrical study in the maxilla of pigs

Objectives: The purpose of the present study was to histologically compare the bone tissue responses to surface-modified zirconia and titanium implants.
Methods: Threaded zirconia implants were produced using a new low-pressure injection moulding technique and thereafter surface treated by acid etching. Titanium implants with the exact shape and surface treated by sandblasting and acid etching (SLA) served as controls. Fifteen adult pigs received both implant types in the maxilla 6 months after extraction of the second and third incisors. The animals were sacrificed after 4, 8 and 12 weeks and 30 implants with surrounding bone were retrieved.
Results: Histological evaluation showed osseous integration for both materials. Zirconia implants revealed mean peri-implant bone density values of 42.3% (SD ± 14.5) at 4 weeks, 52.6% (SD ± 5.7) at 8 weeks and 54.6% (SD ± 11.5) at 12 weeks after implantation, whereas Ti-SLA implants demonstrated mean values of 29% (SD ± 10), 44.1% (SD ± 18) and 51.6% (SD ± 8.6) at corresponding time intervals. With respect to the bone–implant contact ratio, the mean values for zirconia ranged between 27.1% (SD ± 3.5) and 51.1% (SD ± 12.4) and for Ti-SLA, it ranged between 23.5% (SD ± 7.5) and 58.5% (SD ± 11.4).
For the parameters investigated, no statistically significant differences between both types of implants could be detected at any time point.
Conclusions: No statistical difference between implants could be demonstrated with any of the methods used. The limited number of animals per group, however, does not allow to conclude that there is no difference in osseointegration between the two types of implants, although the data tend to suggest such a trend.     

The influence of simultaneous versus delayed placement on the stability of titanium implants in onlay bone grafts. A histologic and biomechanic study in the rabbit.

A rabbit model was used to study the healing and stability of titanium implants in free bone grafts, placed simultaneously or after 8 weeks of healing and followed for 24 weeks. The skull bone was used as donor site and the tibial metaphysis as recipient site. Stability measurements were performed by using resonance frequency analysis (RFA) at implant placement and after 4, 8, 16 and 24 weeks of healing. Statistically significant higher resonance frequencies were measured at all time points for the delayed approach implants. Removal torque tests after 24 weeks revealed no differences between the two procedures. Histologic ground sections were prepared on specimens taken after 8, 16 and 24 weeks of healing. More bone-implant contacts were observed in the bone graft for the implants inserted in a delayed fashion, while there was no statistically significant difference in the degree of total bone-implant contact between the two groups. It is concluded that delayed implant placement in autogenous onlay bone grafts results in a better integration and stability of the implants.     

Is the osseointegration of immediately and delayed loaded implants the same?—comparison of the implant stability during a 3‐month healing period in a prospective study

Objectives: The objectives of the present study were (1) to compare the stability of delayed loaded (DL) and immediately loaded (IL) ITI SLA implants during the first 3 months of the healing period using resonance frequency analysis (RFA) and (2) to determine the factors that affect implant stability during the healing period.
Materials and methods: To compare implant stability, RFA was performed on two groups of patients (12 patients received 25 IL implants and 47 patients received 79 DL implants) with a total 104 ITI SLA implants. Implant stability was measured directly by RFA at implant placement and consecutively once a week for 12 weeks. Statistical analyses were carried out to study implant stability differences between IL and DL groups.
Results: One of the 25 implants in the IL group failed, and no implant was lost in the DL group. Implant stability between the IL and DL groups showed a statistically significant difference ( P <0.05). The mean implant stability quotient of all measured implants from implant insertion to 12 weeks was 72.88 ± 5.39 for the DL and 75.86 ± 3.60 for the IL types. The lowest stability was at 4 weeks for DL implants (mean: 71.58 ± 5.11) and 2 weeks for IL implants (mean: 71.33 ± 2.97). In both groups, bone types I and II showed higher implant stability than bone type III ( P <0.05).
Conclusions: The findings of this study indicate that differences in osseointegration between IL and DL implants may be predicted according to differential implant stability.     

Immediate placement of implants into periodontally infected sites in dogs. Part 2: A fluorescence microscopy study

PURPOSE: Polychromatic sequence labeling of bone was used to study the effect of periodontal infection on the immediate placement of Frialit-2 implants. MATERIALS AND METHODS: In the surgical first phase, periodontitis was induced with ligatures involving the mandibular premolars of 5 mongrel dogs, and the contralateral teeth were used as controls (received only prophylaxis). After 3 months, the second phase was initiated and 40 implants were placed in the alveoli of both experimental and control teeth. During the healing period, fluorescent bone markers were injected to study bone formation around the implants. The dyes were injected in the following sequence: oxytetracycline hydrochloride at 3 days after implant placement, calcein green 4 weeks after implant placement, oxytetracycline 8 weeks after implant placement, and alizarin red S 3 days before sacrifice. Following a healing period of 12 weeks, the animals were euthanized and the hemimandibles were removed, dissected, fixed, and prepared for histomorphometic analysis of the percentage of each bone marker present. RESULTS: Fluorescence microscopy showed a similar sequence of bone remodeling (Mann-Whitney test) for both groups: experimental group, 9% bone formation at 3 days, 29% at 4 weeks, 21.6% at 8 weeks, and 52% at 12 weeks; control group, 14% at 3 days, 35.2% at 4 weeks, 32.3% at 8 weeks, and 45.8% at 12 weeks. DISCUSSION: Remodeling in both groups had similar characteristics in the degree of bone formation. CONCLUSIONS: It was concluded that periodontal disease does not affect bone remodeling around immediate implants. Although the healing in periodontally infected sites was slower initially, it reached the levels of the non-diseased sites after 12 weeks.     

Influence of a nanometer-scale surface enhancement on de novo bone formation on titanium implants: a histomorphometric study in human maxillae

In this prospective randomized controlled clinical study, small titanium implants were placed in posterior maxillae for the purpose of assessing the rate and extent of new bone development. Nine pairs of site evaluation implants were placed in posterior areas of maxillae and retrieved with trephine drills after 4 or 8 weeks of unloaded healing. The amount of bone in linear contact (%) with the implant surface was used to determine the osteoconductive potential of the implant surface. Implant surfaces were dual acid etched (n = 9) (controls) or dual acid etched and further conditioned with nanometer-scale crystals of calcium phosphate (n = 9) (test implants), and the surfaces were compared. The implants and surrounding tissues were processed for histologic analysis. The mean bone-to-implant contact value for the test surface was significantly increased over that of the control implants at both time intervals (P <.01). For the implants/patients included in this study, the addition of a nanometer-scale calcium phosphate treatment to a dual acid-etched implant surface appeared to increase the extent of bone development after 4 and 8 weeks of healing.     

Influence of different implant surfaces on peri-implant osteogenesis: histomorphometric analysis in sheep

BACKGROUND: The present study investigated peri-implant osteogenesis and implant biologic fixation in different zirconia sandblasted endosseous titanium surfaces (SLA-60 and SLA-120) and a turned titanium surface (T) 2 and 4 weeks after surgery. METHODS: Seventy-two implant screws were implanted in tibia of six sheep. Histologic sections of implants (2 and 4 weeks after surgery) were analyzed with light microscopy for histomorphometric analysis of bone-to-implant contact (BIC), bone ingrowth (BI), and bone surface (BS/BV). Histologic blocks were used to perform bone microhardness studies next to the implants. Some implants were also observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: In general, the highest values of BIC, BI, BS/BV, and Vickers hardness number (HV) were measured in SLA-60 samples, followed by SLA-120 and T implants. Two weeks after surgery, all the implants appeared biologically fixed by a newly formed woven bone arranged in thin bone trabeculae and filling the gap between implant and host bone. Four weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the SLA-60 and SLA-120 implants by a gradual deposition of parallel-fiber bone. CONCLUSIONS: Our results suggest that, in the early period of peri-implant healing, the implant surface morphology that seemed to influence the increase of peri-implant osteogenesis, bone turnover, and peri-implant bone maturation was SLA-60. We suggest that this surface, characterized by moderately deep titanium cavities very similar to the osteocyte lacunae, could act as a microscopic scaffold for mesenchymal and/or osteoblast-like cells adhesion.     

Early healing of implants placed into fresh extraction sockets: an experimental study in the beagle dog. II: ridge alterations

Aims: To describe the early phases of healing at the alveolar ridge around dental implants placed into fresh extraction sockets and to study whether (i) the dimension of the socket and (ii) a new implant surface nano-topography may have any influence.
Materials and Methods: Sixteen beagle dogs received 64 test (new surface) and control implants randomly placed at the distal socket of 3P3 and 4P4. The implant shoulder was levelled with the marginal buccal bone crest. Animals were sacrificed at 4 h, 1, 2, 4 and 8 weeks for histological examination.
Results: Bone loss occurred at the buccal crest between the 4-h and 1-week healing intervals, being more pronounced at the third premolar site [vertical bone loss between day 0 and 8 weeks 1.1 (0.5) mm]. The corresponding loss at the fourth premolar site was 0.3 (0.5) mm. Test sites containing implants with discrete crystalline deposition nano-particles' surface exhibited less buccal bone resorption than control sites at 8 weeks.
Conclusion: Dimensions of the socket influenced the process of wound healing of implants placed into fresh extraction sockets, with more bone loss in the narrower sockets; however, the implant surface nano-topography seemed to have a limited effect in the healing of this implant surgical protocol.     

Early Bone Healing around Different Implant Bulk Designs and Surgical Techniques: A Study in Dogs

Purpose: To evaluate the bone healing response to different implant root shape designs in a dog model. Materials and Methods: Three by eight millimeter screw‐type short‐pitch (SP) and large‐pitch (LP) implants (Intra‐Lock International, Boca Raton, FL, USA), and 4.5 × 6 mm plateau (P) implants (Bicon LLC, Boston, MA, USA) were placed along the proximal tibia of six dogs for 2 and 4 weeks. The combination of implant design and final osteotomy drilling resulted in healing chambers for the LP and P implants. The implants were nondecalcified processed to plates of ～30‐µm thickness and were evaluated by optical microscopy for healing patterns and bone‐to‐implant contact (BIC). One‐way analysis of variance at 95% level of significance and Tukey's test were utilized for multiple comparisons among the groups' BIC. Results: Microscopy showed a ～150‐µm region of newly deposited bone along the whole perimeter of SP implants, near the edge of the LP implant threads, and plateau tips for P implants. Rapid woven bone formation and filling was observed in regions where surgery and implant design resulted in healing chambers. No significant differences in BIC were observed (p > .75). Conclusions: Different implant design/surgical protocol resulted in varied bone healing patterns. However, the BIC and bone morphology evolution between implant designs were comparable. Regardless of the combination between implant design and final osteotomy drilling, bone morphology evolution from 2 to 4 weeks was comparable.     

Are culture‐expanded autogenous bone cells a clinically reliable option for sinus grafting?

Objectives: This prospective clinical study was designed to examine the healing process during the first 12 months after sinus grafting (SG) with autogenous culture-expanded bone cells (ABC) and bovine bone mineral (BBM) histomorphometrically and radiologically.
Material and methods: Twenty-two sinuses of 12 patients (mean age 56.2±9.3 years) were grafted. Four weeks before, SG bone biopsies were obtained with a trephine burr and the bone cells were isolated and expanded. Every sinus was grafted with BBM and ABC. After 6 months, a biopsy was taken from each sinus and implants ( n =82) were placed. These were uncovered after another 6 months and fitted with dentures. The percent newly formed bone (NB) and the NB-to-BBM contact area were determined on undecalcified histologic sections. The sinus graft volume was evaluated by dental CT after SG (CT 1), after implant placement (CT 2) and after implant uncovery (CT 3).
Results: Postoperative healing was uneventful. The NB was 17.9±4.6% and the contact area 26.8±13.1%. The graft volume (in mm³) was 2218.4±660.9 at the time of CT 1, 1694±470.4 at the time of CT 2 and 1347.9±376.3 at the time of CT 3 ( P <.01). Three implants were lost after uncovery. Reimplantation and prosthodontic rehabilitation were successful throughout.
Conclusions: These results suggest that SG with ABC and BBM in a clinical setting provides a bony implant site which permits implant placement and will tolerate functional loading.     

Bone tissue responses to glass fiber-reinforced composite implants – a histomorphometric study

Objectives: The aims of this study were to evaluate bone-to-implant contact (BIC) and the osteoconductive capacity of bioactive fiber-reinforced composite implant (FRC) in vivo .
Material and methods: Threaded sand-blasted FRC implants and threaded FRC implants with bioactive glass (BAG) were fabricated for the study. Titanium implants were used as a reference. Eighteen implants (diameter 4.1 mm, length 10 mm) were implanted in the tibia of six pigs using the press-fit technique. The animals were sacrificed after 4 and 12 weeks. Histomorphometric and scanning electron microscopic (SEM) analyses were performed to characterize BIC.
Results: In general, the highest values of BIC were measured in FRC-BAG implants, followed by FRC and Ti implants. At 4 weeks, the BIC was 33% for threaded FRC-BAG, 27% for FRC and 19% for Ti. At 12 weeks, BIC was 47% for threaded FRC-BAG, 40% for FRC and 42% for Ti. Four weeks after implantation, all the implants appeared biologically fixed by a newly formed woven bone arranged in the thin bone trabeculae filling the gap between the implant and the bone of the recipient site. Twelve weeks after implantation, the thickness of the woven bone trabeculae had increased, especially around the FRC-BAG implants.
Conclusion: Our results suggest that the FRC implant is biocompatible in bone. The biological behavior of FRC was comparable to that of Ti after 4 and 12 weeks of implantation. Furthermore, the addition of BAG to the FRC implant increased peri-implant osteogenesis and bone maturation.     

Implant stability in relation to osseointegration: an experimental study in the Labrador dog

Objective: Resonance frequency analysis (RFA) is supposed to determine implant stability. The relation between RFA and the degree of bone-to-implant contact (BIC), however, is unclear. The objective of the present experiment was to evaluate RFA values in relation to osseointegration.
Material and methods: In 20 Labrador dogs, all mandibular premolars were extracted bilaterally. After 3 months, four transmucosal screw-shaped experimental implants were placed in each mandibular premolar region. The implants (12 mm length, Ø 4.1 mm, insertion depth 9 mm) were either SLA surface or turned surface implants. The animals were divided into four groups (five dogs in each group) to study healing following implant installation at 2 h, 4 days, 1, 2, 4, 6, 8 and 12 weeks. Two experimental implants of each type were installed in each edentulous premolar region. A plaque control program was initiated 2 weeks after each implant installation. RFA assessments were performed at the time of implant installation, at one to three occasions during the monitoring period and at the termination of the experiment. At the end of the experiment, the dogs were sacrificed and each implant site was dissected and processed for histological analysis. The results of the histological analysis, i.e. marginal bone level, degree of osseointegration (BIC%) and bone density, were compared with the corresponding Implant Stability Quotient (ISQ) values of the RFA assessment.
Results: No correlations between histological parameters of osseointegration and ISQ values could be identified. Marginal bone level changes, differences in BIC% and bone density were not reflected in the RFA at any time-point during the 12-week monitoring period.
Conclusion: The value of RFA to predict implant stability over time and to determine at which time-point an implant may be exposed to functional load has to be questioned.     

Trabecular bone response to titanium implants with a thin carbonate-containing apatite coating applied using the molecular precursor method

PURPOSE: The influence of thin carbonate-containing apatite (CA) coating on the trabecular bone response to titanium implants was investigated. MATERIALS AND METHODS: Thin CA coatings were deposited by a new method known as the molecular precursor method. Using a precursor solution composed of an EDTA-calcium complex, a CA film was deposited on the titanium surfaces. Uncoated and CA-coated titanium were placed in the trabecular bone of the left and right femoral condyles of 16 rabbits. After implantation periods of 2, 4, 8, and 12 weeks, the bone-implant interface was evaluated histologically and histomorphometrically. RESULTS: Histologic evaluation revealed new bone formation around the uncoated and CA-coated implant surfaces after only 4 weeks of implantation. After 12 weeks, mature trabecular bone surrounded all implants. At 4 and 8 weeks of implantation, no difference existed in bone contact between uncoated and CA-coated implants. After 12 weeks of implantation, the CA-coated implant group showed a significantly higher percentage of bone contact than the uncoated implant group. DISCUSSION AND CONCLUSION: The present study demonstrated that thin CA coatings applied using the molecular precursor method showed greater bone-to-implant contact during the healing phase than uncoated controls. The results were similar to those observed with implants with calcium phosphate coatings deposited with a physical vapor deposition technique.     

Bone healing at implants with a fluoride-modified surface: an experimental study in dogs

OBJECTIVES: The aim of the present experiment was to study early stages of osseointegration to implants with a fluoride-modified surface. MATERIAL AND METHODS: Six mongrel dogs, about 1-year old, were used. All mandibular premolars and the first mandibular molars were extracted. Three months later, mucoperiosteal flaps were elevated in one side of the mandible and six sites were identified for implant placement. The control implants (MicroThread) had a TiOblast surface, while the test implants (OsseoSpeed) had a fluoride-modified TiOblast surface. Both types of implants had a similar geometry, a diameter of 3.5 mm and were 8 mm long. Following installation, cover screws were placed and the flaps were adjusted and sutured to cover all implants. Four weeks after the first implant surgery, the installation procedure was repeated in the opposite side of the mandible. Two weeks later, biopsies were obtained and prepared for histological analysis. The void that occurred between the cut bone wall of the recipient site and the macro-threads of the implant immediately following implant installation was used to study early bone formation. RESULTS: It was demonstrated that the amount of new bone that formed in the voids within the first 2 weeks of healing was larger at fluoride-modified implants (test) than at TiOblast (control) implants. It was further observed that the amount of bone-to-implant contact that had been established after 2 weeks in the macro-threaded portion of the implant was significantly larger at the test implants than at the controls. CONCLUSION: It is suggested that the fluoride-modified implant surface promotes osseointegration in the early phase of healing following implant installation.