A comparative evaluation between aluminium and titanium dioxide microparticles for blasting the surface titanium dental implants: an experimental study in rabbits.

OBJECTIVE: The aim of this study was to compare, through biomechanical and histological analysis, the aluminium (AlO2) and titanium dioxide (TiO2) microparticles for blasting during the sandblasting acid surface treatment in titanium dental implants using a rabbit tibia model. MATERIALS AND METHODS: Forty-eight commercially available titanium dental implants were divided into two test groups (n = 24 per group): implants with surface treated by AlO2 followed by acid etching as control group (Con group) and implants with surface treated by TiO2 followed by acid etching as test group (Test group). The implants were randomly installed in both tibias of eight rabbits and block samples were removed 4 and 8 weeks after implantation. Resonance Frequency Analyses were performed immediately after the implantation and at 8 weeks. Twelve implants of each group were removed to measure the reverse torque. The remaining implants were used for histological analysis. The data were compared using statistical tests (α = 0.05). RESULTS: In comparing the implant stability quotient at the two time points, no significant statistical differences were found (P > 0.05), as well as in the removal torque test at 8 weeks after implant placement, no found significant difference between the two groups was tested. Histomorphometric analysis showed a high degree of bone organization in all samples with no significant difference between groups in the bone-to-implant contact (P > 0.05). CONCLUSION: Within the limitations of this study, the results indicate that the media of surface blasting (AlO2 or TiO2 microparticles) did not show significant differences in the tested parameters for assessing the osseointegration of the implants.

Topical applications of vitamin D on implant surface for bone-to-implant contact enhance: a pilot study in dogs part II.

OBJECTIVE: The aim of this study was to evaluate the effect of topical application of vitamin D over implant surface, placed immediately to the extraction, throughout histological and histomorphometric analysis of peri-implant tissue. MATERIAL AND METHODS: Six American foxhound dogs were used in the study. Mandibular premolar distal roots were extracted. Twenty-four immediate conical C1 implants (MIS, Barlev, Israel) were randomly assigned to the distal site on each site of the mandible in three groups: (Group CI) 12 titanium implants alone; (Test Group DI) 12 titanium implants supplemented with vitamin D. Prior to implanting, test implants (DI) were submerged in vitamin D 10% solution. No treatment was applied at control implants (CI). After 12 weeks, animals were sacrificed. Block sections were obtained and processed for mineralized ground sectioning. Bone-to-implant contact (Total BIC and BIC%), new bone formation (NBF), interthread bone (ITB), and histological linear measurements (HLM) were analyzed. RESULTS: At 12 weeks, all implants were clinically stable and histologically osseointegrated. BIC evaluation showed Total BIC mean and SD values for DI (48.96 ± 2.14), CI (44.56 ± 1.75) (P < 0.05), BIC% DI (43.59 ± 0.98), and CI (42.67 ± 9.26) (P > 0.05). For interthread bone formation, values were as follows: DI (15.21 ± 3.87), CI (14.79 ± 1.45) (P > 0.05), no statistically differences. Regarding peri-implant new bone formation, no statistically differences could be found between the two groups DI (31.87 ± 1.23), CI (27.18 ± 2.38) (P > 0.05). For linear measurements, test group (DI) showed statistically significant less buccal crestal bone loss (CBL) DI (0.37 ± 0.12)*, CI (1.26 ± 0.8) (P < 0.05), and vitamin D implants showed less lingual junctional epithelium DI (1.58 ± 0.43)*, CI (2.18 ± 0.48) (P < 0.05). No differences were observed in the buccal mucosa. CONCLUSION: With the limitation of animal studies, topical application of vitamin D on dental implants could reduce crestal bone loss and increase 10% more bone-to-implant contact at 12-week follow-up period.

Bone response to collagenized xenografts of porcine origin (mp3(®) ) and a bovine bone mineral grafting (4BONE(™) XBM) grafts in tibia defects: experimental study in rabbits.

OBJECTIVES: This study aimed to carry out the evaluation of bone response of new bone formation to two different xenografts (bovine and porcine) biomaterials inserted in rabbit tibiae. MATERIALS AND METHODS: The study used a total of 20 male New Zealand albino rabbits. They received a total of 40 grafts in the proximal metaphyseal areas of both tibiae. Two biomaterials were evaluated: 20 porcine xenografts, as a bone granulate (OsteoBiol(®) MP3(®) ; Tecnoss srl, Giaveno, Italy), were placed in the proximal metaphyseal area of the right tibia, 20 anorganic bovine bone mineral grafting (4BONE(™) XBM, MIS Implants Inc., BARLEV, Israel) were placed in the left tibia. Following graft insertion, the animals were sacrificed in two groups of 10 animals, after 1 and 4 months, respectively. For each group, biomaterials were analyzed: newly formed bone, residual graft materials and the connective tissue. Histomorphometric, EDX analysis and element mapping were performed at 1 and 4 months after graft insertion. RESULTS: At 4 months after treatment, the bone defects displayed radiological images that showed complete repair of osseous defects. Histomorphometric evaluation showed that for the porcine xenograft, the study averages for newly formed bone represented 84.23 ± 2.9%, while bovine matrix was 79.34 ± 2.1%. For residual graft material, the porcine biomaterial had 11.23 ± 1.7% and the bovine graft 31.56 ± 2.3%. Finally, the connective tissue for MP3 was 10.33 ± 1.8%, while for the 4BONE(™) XBM we obtained 14.34 ± 2.9%. Element analysis revealed higher percentages of Ca (54 ± 9%) and P (35 ± 6%) in the group B than group A and control group (P < 0.05). CONCLUSIONS: Defects of a critical size in a rabbit tibia model can be sealed using a bovine porous biphasic calcium phosphate and MP3 material; this supports new bone formation, creates a bridge between borders, and facilitates bone ingrowth in both biomaterials. Furthermore, this study observed partial dissolution of the mineral phase of four bone graft and complete resorption of porcine MP3 biomaterial and its incorporation into the surrounding bone. Depending on clinical needs, each biomaterial could be useful in daily clinical practice.

Enhanced bone regeneration with a novel synthetic bone substitute in combination with a new natural cross-linked collagen membrane: radiographic and histomorphometric study.

OBJECTIVES: 4Bone is a fully synthetic bioactive bone substitute composed of 60% hydroxyapatite (HA) and 40% beta-tricalcium phosphate (ß-TCP). This study aimed to investigate the effect of resorbable collagen membranes (RCM) on critical size defects in rabbit tibiae filled with this novel biphasic calcium phosphate at 15, 30, 45, and 60 days by radiological and histomorphometric analysis. MATERIAL AND METHODS: Three critical size defects of 6 mm diameter were created in both tibiae of 20 New Zealand rabbits and divided into three groups according to the filling material: Group A (4Bone), Group B (4Bone plus RCM), and Group C (unfilled control group). At each of the four study periods, five rabbits were sacrificed. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. RESULTS: At the end of treatment, radiological analysis found that cortical defect closure was greater in Group B than Group A, and radiopacity was clearly lower and more heterogeneous in Group A cortical defects than in Group B. There was no cortical defect closure in Group C. Histomorphometric evaluation showed significant differences in newly formed bone and cortical closure in Group B compared with Groups A and C, with the presence of higher density newly formed bone in cortical and medullar zones. CONCLUSIONS: Biphasic calcium phosphate functioned well as a scaffolding material allowing bone ingrowth and mineralization. The addition of absorbable collagen membranes enhanced bone gain compared with non-membrane-treated sites. This rabbit study provides radiological and histological evidence confirming the suitability of this new material for guided tissue regeneration of critical defects.

Bone neo-formation and mineral degradation of 4Bone.(®) Part I: material characterization and SEM study in critical size defects in rabbits.

OBJECTIVE: This study reports the characterization process and in vivo application of a new high-porosity biphasic calcium phosphate (4Bone(®) - HA 60%/ß-TCP 40%) inserted into the critical size defect of a rabbit tibiae. MATERIAL AND METHODS: Two critical size defects of 6 mm diameter were created in each tibia of 15 New Zealand rabbits, and a total of 60 defects were divided into a test group filled with 4Bone(®) (n = 30) and a control group (n = 30). The material and the implants were characterized by scanning electron microscope (SEM) fitted with energy-dispersive X-ray spectroscopy (EDX). RESULTS: The biomaterial's grain size decreased progressively with the graft integration process over the 60-day study period. Element analysis revealed increased percentages of Ca/P (2.86 ± 0.32 vs. 1.97 ± 0.59) in new bone and at the interface (P < 0.05). Element mapping showed that Ca and P were concentrated in the medullary and cortical zones in the test group but were concentrated only in cortical zones in the control group. CONCLUSIONS: Critical size defects in a rabbit tibia model can be sealed using this highly porous biphasic calcium phosphate; it supports new bone formation, creates a bridge between defect borders, and facilitates bone in growth.

Biphasic ß-TCP mixed with silicon increases bone formation in critical site defects in rabbit calvaria.

OBJECTIVE: The aim of this study was to assess the bone regeneration of critical size defects in rabbit calvarias filled with ß-TCP doped with silicon. MATERIALS AND METHODS: Twenty-one New Zealand rabbits were used in this study. Two critical size defects were created in the parietal bones. Three experimental groups were evaluated: Test A (HA/ß-TCP granules alone), Test B (HA/ß-TCP granules plus 3% silicon), Control (empty defect). The animals were sacrificed at 8 and 12 weeks. Evaluation was performed by µCT analysis and histomorphometry. RESULTS: µCT evaluation showed higher volume reduction in Test A group compared with Test B (P < 0.05). The Test B group showed the highest values for cortical closure and bone formation around the particles, followed by Test A and controls (P < 0.05). CONCLUSIONS: Within the limitations of this animal study, it can be concluded that HA/ß-TCP plus 3% silicon increases bone formation in critical size defects in rabbit calvarias, and the incorporation of 3% silicon reduces the resorption rate of the HA/ß-TCP granules.

Influence of biphasic ß-TCP with and without the use of collagen membranes on bone healing of surgically critical size defects. A radiological, histological, and histomorphometric study.

OBJECTIVES: The aim of this study was to investigate, by means of radiological and histomorphometric analysis, the effect of resorbable collagen membranes on critical size defects (CSD) in rabbit tibiae filled with biphasic calcium phosphate. MATERIALS AND METHODS: Three CSD of 6 mm diameter were created in both tibiae of 20 New Zealand rabbits and divided into three groups according to the filling material: Group A (Ossceram), Group B (Ossceram plus Alveoprotect membrane), and Group C (unfilled control group). Five animals from each group were sacrificed after 15, 30, 45, and 60 days. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. RESULTS: At the end of treatment, radiological analysis found that cortical defect closure was greater in Group B than Group A, and radiopacity was clearly lower and more heterogeneous in the Group A cortical defects than in Group B. There was no cortical defect closure in Group C. Histomorphometric evaluation showed significant differences in newly formed bone and cortical closure in Group B compared with Groups A and C, with the presence of higher density newly formed bone in cortical and medullar zones. There was no cortical defect closure or medullar bone formation in Group C. CONCLUSIONS: Biphasic calcium phosphate functioned well as a scaffolding material allowing mineralized tissue formation. Furthermore, the addiction of absorbable collagen membranes enhanced bone gain compared with non-membrane-treated sites.

Peri-implant tissue reactions to immediate nonocclusal loaded implants with different collar design: an experimental study in dogs.

PURPOSE: The aim of this study was to evaluate bone remodelling and soft tissue reactions around immediate nonocclusal loaded implants with different collar configuration in beagle dogs. MATERIAL AND METHODS: The mandibular bilateral second, third and fourth premolars of six beagle dogs were extracted. After 3 months of healing, four implants were placed in the mandibles of each dog. Randomly, two implants with a 1.5 mm polished surface collar (TSA, control group) and two implants with a 0.7 mm polished surface collar and 2.5 mm microthreaded area (TSAA, test group) were inserted. Both groups were treated with a minimal mucoperiosteal flap elevation approach. Impressions were taken and two single screw-retained restorations were inserted in each hemi-mandible 2 days after the implant placement. The animals were sacrificed at 1, 2 and 3 months (two specimens each), and biopsies were obtained. Samples were processed for ground sectioning. Histomorphometric analysis was carried out to compare buccal and lingual bone height loss and soft tissue behaviour between the two groups. RESULTS: Crestal bone resorption was significantly higher in the control group (P > 0.05). The establishment of the biological width showed similar outcomes for both groups. Only the distance from the top of the peri-implant mucosa to the apical portion of the barrier epithelium at lingual aspect was significantly more pronounced in the control group (P > 0.05). CONCLUSIONS: The alterations that occurred in the peri-implant tissues were related to the adaptation that occurred after the loading conditions in both groups. The microthread design might have an effect in maintaining the marginal bone loss against loading.

Clinical and radiographic evaluation of osseotite-expanded platform implants related to crestal bone loss: a 10-year study.

OBJECTIVE: The aim of this prospective clinical study was to evaluate the survival rates at 10 years of expanded platform implants placed in the anterior zone of the maxilla and immediately restored with single crowns. MATERIALS AND METHODS: Implants incorporating the platform-switching concept were placed in fresh extraction sockets in the maxillary arch, with each patient receiving a provisional restoration immediately after implant placement. After 15 days, final screwed restorations were inserted. Mesial and distal bone heights were evaluated using digital radiography on the day following implant placement and at 1, 5, 7, and 10 years. Primary stability was measured with resonance frequency analysis (RFA) using the Osstell Mentor device. Eighty-six implants were placed in 32 men and 32 women ranging in age between 29 and 60 (mean, 39.64 ± 5.16 years). RESULTS: Marginal bone loss from implant collar to bone crest between baseline and 10 years follow-up was 1.01 mm ± 0.22. Mesial site crestal bone loss ranged from 3.57 mm ± 1.1 at baseline to 3.77 mm ± 0.7 at 10-year. Distal site crestal bone loss ranged from 3.49 mm ± 0.8 at baseline to 3.73 mm ± 0.7 at 10 year. CONCLUSION: The platform-switched implants remained stable over the course of 10 years and had an overall survival rate of 97.1%.

Melatonin stimulates the growth of new bone around implants in the tibia of rabbits.

This study evaluated the effect of the topical application of melatonin in accelerating bone formation associated with implants 2 months after their application to the tibiae of rabbits. Twenty New Zealand rabbits were used. Twenty implants treated with melatonin and 20 control implants without melatonin were placed in the proximal metaphyseal area of each tibia. Studies of new bone formation were subsequently made at 15, 30, 45 and 60 days. Cortical width and cortical length of new bone formation were measured. Following implantation, an anteroposterior and lateral radiologic study was carried out. Collected samples were sectioned at 5 µm and stained using hematoxylin-eosin, Masson's trichromic and Gordon-Switt reticulin stains. After a 60 day treatment period, melatonin increased the length of cortical bone (95.13±0.42%) versus that around control implants (62.91±1.45%). Related to the perimeter of cortical bone of the tibiae, melatonin induced new bone 88.35±1.56% versus 60.20±1.67% in the control implants. Melatonin regenerated the width and length of cortical bone around implants in tibiae of rabbits more quickly than around control implants without the addition of melatonin.

Evaluation of periimplant bone neoformation using different scanning electron microscope methods for measuring BIC. A dog study.

OBJECTIVES: [corrected] The aim of this study was to determine which of three methods for measuring BIC (bone-to-implant contact), using vestibular and lingual scanning electron microscopy (SEM) for different implant systems at 15, 30 and 90 days post-surgery was the most precise. An elemental analysis with SEM was used to evaluate neoformed bone composition for three implant systems at the same study times. MATERIAL AND METHODS: 36 implants were placed in eighteen Beagle dogs mandible about one year old and weighing approximately 12-13 kg in order to evaluate bone apposition to three different implant surfaces. It was used the third and fourth premolar and first molar distal sockets in both quadrants of the mandible (3P3, 4P4 and 1M1). Teeth were hemi-sected and the distal roots were removed. The specimens were prepared for histological examination and each section surface was stained using Masson's trichrome and hematoxylin and eosin stains. BIC evaluations were performed by the three methods, BIC I (the quantity of mineralized bone in direct contact with the implant's titanium surface across the entire threaded area); BIC II (along a line that passes from apex to apex of the implant threads); BIC III (both in areas around and above the threads and in between threads). RESULTS: Both BIC and bone content were analyzed for all implants placed in P3, P4 y M1 alveoli on both, the buccal and palatine sides (elemental analysis quantified Ca, P, O and C). It was seen it was only at the ninety-day mark that high percentages of calcium were present. CONCLUSIONS: This study suggest that BIC III evaluation is the most certain method for establishing the quantity of bone formed as the BIC area. Key words:Bone-to-impant contact, dogs, extraction socket, implants.