Histomorphometric and microtomographic analysis of maxillary sinus augmentation surgeries with and without collagen membrane on the lateral window: A randomized clinical trial.

OBJECTIVE: To evaluate the histomorphometric and computerized microtomographic (Micro-CT) analysis of the regenerated bone tissue from maxillary sinus augmentation surgery, with and without using the collagen membrane on the external osteotomy window. MATERIALS AND METHODS: Twelve patients were selected for this prospective, controlled, and randomized study. The patients were submitted to bilateral maxillary sinus surgery in a split-mouth design. On the test side, the maxillary sinus augmentation procedure included using Geistlich Bio-Oss® and a Geistlich Bio-Gide® collagen membrane covering the lateral osteotomy window. On the control side, only Geistlich Bio-Oss® was used without the presence of the membrane. After 6 months, the surgeries for implant installation were performed. In this surgical phase, specimens of the regenerated tissue were collected for histological and Micro-CT analysis. RESULTS: In the histomorphometric evaluation, the mean (±SD) percentages of newly formed bone were 43.9% (±11.5) and 40.8% (±8.9) in the test and control groups, respectively. The corresponding values of the Micro-CT analysis were 36.6% (±3.4) and 37.2% (±4.7) in the test and control groups, respectively. There was no statistically significant difference between the test and control groups in the two methods. In addition, there was no statistically significant difference between the mean percentage of biomaterial remaining between the test and control groups. However, the mean percentage of newly formed bone was significantly higher and the mean percentage of remaining biomaterial was significantly lower in the histomorphometric analysis compared to the values obtained through microtomography. CONCLUSION: The additional use of collagen membranes in maxillary sinus surgery does not offer advantages in newly formed bone.

Evaluation of Pink and White Esthetic Scores for Immediately Placed and Provisionally Restored Implants in the Anterior Maxilla.

PURPOSE: To evaluate the esthetic result of immediately placed implants with immediate provisional restorations in the anterior maxilla using the pink esthetic score (PES) and white esthetic score (WES). MATERIALS AND METHODS: The records of patients were evaluated retrospectively. The evaluation was carried out by two examiners using 12 evaluation criteria. RESULTS: The average PES value from the evaluation of 53 images obtained from the 53 selected patients (22 men and 31 women) was 8.63 ± 2.4 (range, 1-14), whereas the average WES value was 6.92 ± 1.67 (range, 2-10). The mesial papilla had the highest average PES (1.39 ± 0.4) and the distal papilla had the lowest PES (0.87 ± 0.54). Texture had the highest average WES (1.54 ± 0.34) and tooth shape had the lowest average WES (1.25 ± 0.43). CONCLUSION: Treatment with immediate implants providing immediate provisional restoration in the anterior maxilla yields good clinical esthetic outcomes, as assessed by PES/WES values. The PES and WES values showed strong intraexaminer agreement, but weak interexaminer agreement.

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.

Peri-implant bone loss around single and multiple prostheses: systematic review and meta-analysis.

PURPOSE: The objective of this systematic review and meta-analysis was to assess and compare the marginal bone loss around implants supporting single fixed prostheses and multiple-unit screw-retained prostheses. MATERIALS AND METHODS: The literature was searched manually and electronically to identify studies in which the marginal peri-implant bone loss around single-implant prostheses and screw-retained multiple-implant prostheses was evaluated radiographically. Two reviewers independently selected the literature and extracted the data. The random-effects method was used to obtain estimates of marginal peri-implant bone loss (means and 95% confidence intervals [CIs]). RESULTS: Of the 2,107 studies identified by a preliminary search, 17 fulfilled the inclusion criteria; 7 were related to single-implant prostheses and 10 to multiple-implant screw-retained fixed prostheses. The mean marginal peri-implant bone loss was 0.9 mm (95% CI, 0.49 to 1.32 mm) for multiple-implant screw-retained prostheses and 0.58 mm (95% CI, 0.37 to 0.80 mm) for single-implant prostheses. CONCLUSION: This indirect comparison provided no evidence to support the assertion that there are differences in marginal peri-implant bone loss between single implant prostheses and multiple screw-retained prostheses.

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.

Effectiveness of implant surface decontamination using a high-pressure sodium bicarbonate protocol: an in vitro study.

OBJECTIVES: To evaluate the effectiveness of a high-pressure sodium bicarbonate spray protocol to decontaminate implant surfaces intentionally inoculated with bacteria. MATERIALS AND METHODS: Twenty commercially pure titanium implants, 10 with machined surfaces and 10 with rough surfaces, were inoculated with Streptococcus sanguis and then submitted to a decontamination protocol using a high-pressure sodium bicarbonate spray device for 1 minute under aseptic conditions. RESULTS: After the application of the decontamination protocol, all bacterial cells were removed from the tested implants, regardless of surface roughness. CONCLUSION: The results suggest that regardless of the implant surface roughness, the protocol using high-pressure sodium bicarbonate spray for 1 minute, under aseptic conditions, was effective in removing all the viable bacterial cells.

An in vitro model to evaluate the accuracy of guided surgery systems.

PURPOSE: An in vitro model was developed and tested to evaluate the precision of guided implant systems. The accuracy of dental implants placed with a flapless technique was analyzed using a stereolithographic template in vitro. Differences between the virtual and actual positions of the implants were measured. MATERIALS AND METHODS: Six polyurethane mandibles with artificial silicone gums were fabricated, and each was fitted with an individual computed tomography (CT) guide. Stereolithographic guides were created using computer-aided design/computer-assisted manufacturing technology and virtual planning software. All stereolithographic guides had four holes for stabilization pins and three holes for cylindric implants. After implant placement, the mandibles were subjected to another CT scan to compare the actual implant positions with the planned positions. The pre- and postimplantation CT images were superimposed using digital processing image software to evaluate the linear and angular deviations between the virtual planning data and the surgical results. RESULTS: The mean angular discrepancy between the virtual and actual positions of the 18 placed implants was 2.16 ± 0.92 degrees. Among the placed implants, 66.7% were situated a mean of 0.38 ± 0.03 mm apical to the planned vertical position, and 33.3% were situated 0.39 ± 0.03 mm coronal to the planned position. CONCLUSIONS: Within the limitations of the present study, this tool showed promising accuracy in virtual implant placement.

Evaluation of implant-abutment microgap and bacterial leakage in five external-hex implant systems: an in vitro study.

PURPOSE: The aim of the present study was to verify the presence of a microgap between implants and prosthetic abutments on their external surfaces in five different external-hex implant systems and to determine whether bacterial leakage occurs through the implant-abutment (I-A) interface. MATERIALS AND METHODS: Ten samples of each implant system were used. Eight samples of each implant system were inoculated with 0.3 µL of a suspension of Escherichia coli for bacterial leakage evaluation. Two other samples were used as controls. Sample analysis was accomplished at 24 and 48 hours and on the 5th, 7th, and 14th day after inoculation. After microbiologic analysis, all samples were prepared for I-A interface evaluation by scanning electron microscopy. The mean of the microgap misfit was obtained from six points at x1,000 and x3,000 magnifications. RESULTS: The Neodent implant system (0.51 ± 0.39 µm) showed the closest adaptation, followed by Dentoflex (1.44 ± 0.73 µm), Titanium Fix (1.88 ± 1.28 µm), SIN (2.46 ± 3.38 µm), and Conexão (2.68 ± 3.02 Μm). Twenty-five percent of the Dentoflex samples showed bacterial leakage through the I-A interface; no other implant system presented bacterial leakage. CONCLUSION: The width of the microgap at the I-A interface was less than 3 µm in all systems. A direct correlation between bacterial leakage and I-A interface misfit was not observed.

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.

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.

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.

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 beta-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 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.

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 different 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.

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.

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-microm particles and Group 3 with 250-microm 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 (R(a)) per group was: Group 1, 0.17 microm +/- 0.01; Group 2, 1.14 microm +/- 0.15; and Group 3, 3.17 microm +/- 0.23. After the contamination period, Group 1 remained with 49 x 10(3) bacterial cells, and the bacterial concentrations of Groups 2 and 3 were 11 x 10(4) and 35 x 10(5), 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.