Guaracilei Maciel Vidigal

Influence of titanium surface roughness on attachment of Streptococcus sanguis: an in vitro study.

The purpose of the present study was to investigate the efficacy of the decontamination protocol for bacterial removal in titanium surfaces with three different levels of roughness using a high-pressure sodium bicarbonate device for 1 minute under aseptic conditions. Group 1 was composed of 10 as-machined titanium sheets and Groups 2 and 3 of titanium sheets blasted with aluminum oxide (Al2O3, alumina) particles with different diameters: Group 2 was blasted with 65-&mgr;m particles and Group 3 with 250-&mgr;m particles. The titanium specimens were sterilized and incubated in tubes containing a suspension of Streptococcus sanguis. The colony-forming units were counted before and after the application of the decontamination protocol. The arithmetic mean roughness (Ra) per group was: Group 1, 0.17 &mgr;m ± 0.01; Group 2, 1.14&mgr;m ± 0.15; and Group 3, 3.17 &mgr;m ± 0.23. After the contamination period, Group 1 remained with 49 × 103 bacterial cells, and the bacterial concentrations of Groups 2 and 3 were 11 × 104 and 35 × 105, respectively. After the application of the decontamination protocol, no viable bacteria were detected. With the increase of the surface roughness, an exponential increase in bacterial cells was observed. The results showed that the decontamination protocol treatment with a high-pressure sodium bicarbonate device efficiently removed all bacterial cells in all surfaces tested. This indicates that high-pressure sodium bicarbonate spray should be used in the maintenance phase of implant treatment.

Osseointegration of titanium alloy and HA-coated implants in healthy and ovariectomized animals: a histomorphometric study.

OBJECTIVES The objective of the present study is to evaluate the response to dental implants in healthy and osteoporotic bone. MATERIALS AND METHODS Ten ovariectomized (OVX) New Zealand rabbits submitted to a hypocalcic diet and 10 sham-aged rabbits were used. All animals were submitted to bone mineral density (BMD) measurements before ovariectomy, and also 4 months afterwards, using dual energy X-ray absorptiometry. The BMD measurements showed a significant loss of bone mass, between the first and second examinations, only in the experimental group (P<0.05). After the bone mass loss induction period, three different implants were installed in the proximal tibia metaphisis of each animal: a titanium alloy implant (Ti), a plasma-spray hydroxyapatite-coated implant (HA-PS), and another implant coated with hydroxyapatite with the biomimetic process (HA-B). RESULTS After 3 months, histomorphometry showed a bone-to-implant contact (BIC) for Ti implants of 73.09+/-13.74% in healthy and 66.09+/-30.01% in OVX animals. The BIC for the HA-PS was 64.83+/-15.65% and 90.17+/-8.14% for healthy and OVX animals, respectively, and 88.66+/-5.30% and 87.96+/-10.71% for the HA-B implants placed in the same conditions. The differences between the implants in healthy and OVX conditions were not statistically significant (P>0.05). The only significant difference within groups was observed in the healthy animals between HA-B and Ti implants (P<0.06). CONCLUSION Within the parameters used in this animal model it was not possible to observe BIC differences between osteoporotic and healthy animals.

Tridimensional analysis of maxillary sinus anatomy related to sinus lift procedure.

Purpose:To evaluate the angulation of the maxillary sinus walls at the apical sinus region. Materials and Methods:Using preoperative computerized tomographies of 15 patients selected for sinus lift procedures, the angulation of the maxillary sinus floor was measured drawing straight lines tangential to the mesial and lateral walls. The measurements were taken from sagittal images at specific areas (i.e., second bicuspid, first molar, and second molar). Results:The results showed that the second bicuspid sites have a sharper angulation than the second molar sites, and these second molar sites have a sharper angle than the first molar sites. Conclusion:The sharper angle observed in the second bicuspid area can influence the feasibility of schneiderian membrane evaluation when compared to the molar areas.

Comparative analysis of microorganism species succession on three implant surfaces with different roughness: an in vivo study.

Purpose:Because almost all implant systems reveal marginal bone loss and some implants can be affected by periimplantitis, to realize an effective maintenance treatment it is important to understand the biofilm development over different implant surfaces. The objective of this human study is to comparatively analyze the kinetics of microorganism species succession on 3 surfaces. Materials and Methods:Three commercially pure titanium sheets with different roughness were randomly fixed bilaterally on the lingual regions of Hawley-type plates of 6 volunteers. The participants used the apparatuses in the following experimental periods: 1, 3, 7, 14, and 21 days, and were instructed to remove the acrylic plates only during oral hygiene procedures. Samples of biofilm were harvested from the central areas of each sheet, and the presence of 24 bacterial species was identified using Checkerboard DNA-DNA Hybridization method. Results:The results showed no statistically significant differences with regard to the kinetics of bacterial species succession on the different surfaces, in all periods of time. Rough surfaces were not more prone to colonization by pathogenic bacteria than the smooth surfaces. Conclusion:The surface roughness does not affect the bacterial species succession in the biofilm. The succession of species was similar during all periods of the study.

Surface characterization of dental implants coated with hydroxyapatite by plasma spray and biomimetic process.

Purpose:The aim of this study was to characterize implants coated with hydroxyapatite (HA) using 2 different processes. Materials and Methods:Commercially pure titanium implants were coated with HA using a modified biomimetic process and the plasma spray process. These implants were characterized by scanning electron microscopy, Fourier-transformed infrared spectroscopy, and x-ray photoelectron spectroscopy. Results:The plasma spray process generates a typical rough topography mainly consisting of HA. The HA coating produced by biomimetic process was partially dissolved in water and only a very thin layer of calcium titanate plus calcium phosphate and probably &bgr;-tricalcium phosphate remained. In vitro test showed that both coatings can be considered bioactive. Conclusion:The modified biomimetic process seems to be a simple and low-cost alternative to coat titanium with a high potential of In vitro application.

Histomorphometric Analyses Of Bone Interface With Titanium-Aluminum-Vanadium and Hydroxyapatite-Coated Implants by Biomimetic Process

Purpose:The surface properties of dental implants have been considered directly related to the success of the osseointegrated interface. Hydroxyapatite (HA)-coated implants promote a bioactive surface because they facilitate cellular migration and bone growth, resulting in a faster osseointegration. Materials and Methods:This study analyzed and compared 2 differen implant surfaces: a group composed of titanium implants and another group coated with HA. The HA coating was produced by the biomimetic process to reduce costs. Results and Conclusions:After histomorphometric analyses it was possible to demonstrate that there were no statistically significant differences between the groups.

Can inorganic bovine bone grafts present distinct properties

The aim of this study was to evaluate the physicochemical characteristics of 3 mineralized bovine inorganic biomaterials and correlate them with the dissolution rate. Bio-Oss(r), GenoxInorgânico(r), and Bonefill(r) were examined using field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), specific surface area (BET), calcium/phosphorous molar ratio and a dissolution assay. Bio-Oss(r) showed a micro- and nanoporous structure consisting of 15-nm hydroxyapatite (HA) crystallites; Genox(r), a microporous structure composed of 39-nm HA crystallites; and Bonefill(r), micro- and nanoporous structure of indeterminable crystallite size. FTIR analysis showed that Bio-Oss(r) and Genox(r) were composed of calcium phosphate. The absorption bands of phosphate were poorly defined in Bonefill(r). By XRD, Bio-Oss(r) was shown to contain peaks related to the carbonated HA, whereas Genox(r) only contained peaks corresponding to HA. The broad bands in Bonefill(r) indicated low crystallinity. Bio-Oss(r) showed a greater surface area and calcium release rate than that of Genox(r). Although all biomaterials were of bovine origin, the different manufacturing processes result in materials with different physicochemical properties and may influence the biological and clinical response.

Histomorphometric analysis of HA-coated implants interface with irradiated and nonirradiated bone.

Purpose:The purpose of the present study was to investigate whether osseointegration of HA-coated implants can be affected by irradiation. Materials and Methods:A single dose of 15 Gy was applied to the right tibia of 5 rabbits and the left tibia was not irradiated and used as control. After 3 months, the animals were killed and the quantification of the implant-bone contact surfaces was performed using scanning electron micrographs of the resin sections containing the implants in the irradiated and nonirradiated bones. After the healing period, all implants were stable. Results:The results show a mean percentage of bone-implant contact of 45.52% in the irradiated tissue and 47.56% in the nonirradiated tissue, with no statistic significant difference (P > 0.05). Conclusion:In conclusion, radiotherapy may not interfere with osseointegration process around HA-coated implants in rabbit cortical bone.

Evaluation of bone width lateral to the mandibular canal as an alternative approach for implant installation.

Purpose:The objective of the present study was to realize an indirect morphometric evaluation of bone thickness lateral to the mandibular canal. Material and Methods:In 30 partially or totally edentulous dry jaws, the first and second molar areas were analyzed using computed tomography. Results:The findings indicated that 28.33% of the sites could be considered for the installation of a standard 3.75-mm-diameter implant laterally between the mandibular canal and its bony counterpart. Conclusion:Implant installation in the posterior mandible region, lateral to the mandibular canal, is an alternative to more complex techniques, such as vertical ridge augmentation.

Histomorphometric analysis of hydroxyapatite-coated implants in rabbit cortical bone using longitudinal and transverse histologic sections.

Purpose:The aim of this study was to compare the osseointegration percentage of biomimetic hydroxyapatite (HA)-coated implants on longitudinal and transverse histologic sections using scanning electron microscopy. Materials and Methods:Ten commercially pure titanium dental implants, measuring 3.75 mm in diameter and 10 mm in length, were coated with HA by the biomimetic process and installed on the proximal metaphysis of the right tibia of 10 adult New Zealand female rabbits (Oryctolagus cunniculus). After a 3-month healing period, the animals were killed and the implants were removed together with the neighboring bone tissue. The specimens were than dehydrated on a crescent concentration of ethanol solution and embedded on resin. The osseointegration percentage of biomimetic HA-coated implants on 1 longitudinal and 1 transverse section were compared, using scanning electron microscopy and computerized histomorphometry. Results:It was verified that there were no statistically significant differences between the results of the different histological section directions (P > 0.05). Conclusion:Thus, in this study, the direction of histological sections did not affect bone-implant percentage.