Sequential morphometric evaluation at UnicCa® and SLActive® implant surfaces. An experimental study in the dog.

AIM: To study sequential osseointegration around implants with nano-technologically modified surfaces at different periods of healing. MATERIALS AND METHODS: After 3 months, two different implant systems with different nano-technologically modified surfaces were randomly installed in the edentulous molar regions of the mandible of 12 dogs. One surface was acid-etched surface, and subsequently modified with calcium ions (UnicCa® ), while the other was a hydrophilic sandblasted with large grit and acid-etched (SLActive® ) surface. The implants were fully submerged, and biopsies were obtained representing the healing after 1, 2, 4 and 8 weeks (n = 6 per period). A morphometric evaluation of densities of new soft tissues (provisional matrix and immature bone marrow), new and old bone, mature bone marrow, vessels and other tissues (bone debris/particles and clot) was performed in the spongiosa compartment of the sites of implantation. RESULTS: After 1 week of healing, the soft tissues, mainly composed of provisional matrix, were present at 41.5 ± 23.9% and 30.1 ± 20.0% at the UnicCa® and SLActive surfaces, respectively. These percentages were >40% at both surfaces after 2 weeks of healing, presenting greater amount of immature bone marrow. Subsequently, these percentages decreased up to disappear after 8 weeks of healing. New bone increased progressively between 1 and 8 weeks of healing from 8.2 ± 3.0% to 77.1 ± 6.4% and from 6.8 ± 2.8% to 67.9 ± 6.8% at the UnicCa® and SLActive® , respectively. Old bone decreased progressively over time. CONCLUSIONS: The patterns of healing at highly hydrophilic surfaces occurred through the early formation of a provisional matrix followed by the formation of new bone and marrow at various stages of maturation. The healing was similar to those described in different animal models, anatomical sites and surgical procedures.

Sequential morphometric evaluation at UnicCa® and DCD® implant surfaces. An experimental study in the dog.

AIM: To study tissue components adjacent to implants with nanotechnologically modified surfaces at different periods of healing. MATERIAL & METHODS: In 12 beagle dogs, two different implant systems with different surface configurations were randomly installed in the edentulous premolar regions of the mandible. One surface was first acid-etched and subsequently, nanotechnologically modified with calcium ions (UnicCa® ), while the other was first sandblasted and acid-etched, and then additionally treated with a nanometer calcium phosphate deposition (discrete crystalline deposition; DCD® ). The implants were fully submerged; surgeries and sacrifices were planned to harvest biopsies after 1, 2, 4 and 8 weeks of healing (n = 6 per period). A morphometric evaluation of percentages of new and old bone, bone debris/particles and clot, new soft tissues (provisional matrix and immature marrow), mature bone marrow and vessels was performed in the spongiosa compartment adjacent to the implant surface up to a distance of about 0.4 mm from the surface. RESULTS: After 2 weeks of healing, the soft tissues were represented by 41.0% at the UnicCa® and 37.9% at the DCD® surfaces, in both cases mainly being composed of provisional matrix. These percentages decreased over time, being composed of greater amounts of immature bone marrow, and disappeared after 8 weeks. New bone increased progressively between 1 and 8 weeks of healing from 9.7 ± 6.3% to 70.0 ± 8.4% and from 8.2 ± 3.5% to 67.0 ± 6.1% at the UnicCa® and DCD® surfaces, respectively. Pristine bone was progressively resorbed. CONCLUSIONS: Throughout the periods of healing observed, the formation of a provisional matrix followed by the formation of new bone and marrow was revealed in a similar fashion as for other modified surface configurations.

Healing of BoneCeramic™ at buccal dehiscence defects at implants installed immediately into extraction sockets. An experimental study in dogs.

OBJECTIVE: To assess the healing outcomes at buccal dehiscence defects after 4 months following implant placement immediately into extraction sockets (IPIES) and filled with a mixture of synthetic hydroxyl apatite (HA) 60% and ß-tri-calcium phosphate (ß-TCP) 40% in comparison with leaving a blood clot. MATERIAL AND METHODS: Eight Labrador dogs were used, and an implant was placed immediately following tooth extraction into the distal alveolus of the third premolars, bilaterally. Standardized buccal defects, 8 mm in depth and 4 mm in width at the coronal and 2 mm in width at the apical outlines were created. A mixture of synthetic HA 60% and ß-TCP 40% was used to fill the defects at the test sites, while the control sites were left unfilled. Collagen membranes were used to cover the defects at both sides, and a non-submerged healing was allowed. After 4 months of healing, biopsies were obtained and processed for morphometric analysis. RESULTS: A vertical gain in the extent of the bony crest and of osseointegration levels of 4.2 ± 2.4 and 3.3 ± 2.1 mm at the test sites and of 5.0 ± 0.8 and 4.6 ± 1.0 mm at the control sites, respectively, were observed. BIC% within the buccal defects reached similar levels (37-42%) both at test and control sites. None of the means of the variables differed significantly between the two groups. New bone formation within the defects was higher, and the percentage of the connective tissue was lower at the control (65.7 ± 11.7% and 2.5 ± 3.3%, respectively) compared to the test sites (16.8 ± 11.3% and 48.9 ± 29.5%, respectively). These differences were statistically significant. CONCLUSIONS: The use of a mixture of synthetic HA 60% and ß-TCP 40% to fill surgically created buccal dehiscence defects at IPIES sites covered with a collagen membrane did not improve osseointegration in the defect area.

Sequential Healing at Implants with Different Configuration and Modified Surfaces: An Experimental Study in the Dog.

PURPOSE: To evaluate the peri-implant soft and hard tissue adaptation at implants with different modified surfaces and configurations. MATERIALS AND METHODS: Six Beagle dogs were used. Mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness flaps were elevated, and two different types of trans-mucosal implants (ICX-Gold®, Medentis Medical GmbH, Dernau, Germany and SLActive®, Institute Straumann, Bern, Switzerland) and two different surfaces were randomly installed in the distal regions of one side of the mandible. Abutments were applied, and a nonsubmerged healing was allowed. After 1 month, the procedures were performed in the other side of the mandible, and after a further month, the animals were sacrificed, biopsies were collected, and ground sections prepared for histological examination. RESULTS: Similar results in marginal bone and soft tissues dimensions were observed after 1 month of healing at the two implant systems used, and no major changes could be observed after 2 months of healing. After 1 month, the percentage of new bone was 69.0% and 68.8% at ICX-Gold and SLActive surfaces, respectively. After 2 months, the percentage of new bone was 67.8% and 71.9% at ICX-Gold Medentis and SLActive surfaces, respectively. No statistically significant differences in osseointegration were found. CONCLUSION: The two implant systems used resulted in similar osseointegration after 1 and 2 months of healing.

Deproteinized Bovine Bone Mineral or Autologous Bone at Dehiscence Type Defects at Implants Installed Immediately into Extraction Sockets: An Experimental Study in Dogs.

PURPOSE: The aim of this study was to evaluate bone regeneration at surgically created dehiscence buccal defects at implants placed immediately into extraction sockets (IPIES) of small dimensions filled with autogenous bone or deproteinized bovine bone mineral (DBBM) associated with a collagen membrane. MATERIALS AND METHODS: Eight Labrador dogs were used and implants were placed immediately into the extraction sockets of the second premolar. The buccal wall was subsequently removed to create a standardized defect, 4 mm wide coronally, 2 mm wide apically, and 6 mm high. Autogenous bone particles (AB) or DBBM granules were used to fill the defects. All surgical sites were subsequently covered by a resorbable collagen membrane and a non-submerged healing was allowed. After 4 months, the animals were euthanized and bone blocks harvested and processed for histomorphometric analysis. RESULTS: The bony crest at the buccal aspect (C) was located 2.3 ± 0.8 mm and 1.7 ± 0.7 mm apically to the implant shoulder (IS) at the AB and DBBM sites, respectively. The coronal levels of osseointegration at the buccal aspect (B) were located 2.7 ± 0.7 mm and 2.2 ± 1.0 mm apically to IS at the AB and DBBM sites, respectively. At the AB sites, the peri-implant mucosa was located 4.3 ± 0.9 mm, 4.7 ± 0.9 mm, and 2.0 ± 1.6 mm coronally to C, B, and IS, respectively. The corresponding values at the DBBM sites were 4.3 ± 0.6 mm, 4.8 ± 0.6 mm, and 2.5 ± 0.8 mm, respectively. No statistically significant differences were found. CONCLUSIONS: The treatment of surgically created buccal defects at IPIES sites using Bio-Oss® (Geistlich Biomaterials, Wolhusen, LU, Switzerland) or autogenous bone, concomitantly with a collagen membrane, engenders bone regeneration to a similar extent after 4 months of healing.

Sequential healing events of osseointegration at UnicCa(®) and SLActive(®) implant surfaces: an experimental study in the dog.

AIM: To study the sequential events in osseointegration at implants with highly hydrophilic surfaces. MATERIAL AND METHODS: All premolars and the first molars were bilaterally extracted in 12 Beagle dogs. After 3 months, full-thickness flaps were elevated and two different implants systems with various surfaces were randomly installed in the edentulous premolar region in one side of the mandible. One surface was acid etched and further modified with calcium ions (UnicCa(®)), while the other was sandblasted with large grits and acid etched (SLActive(®)). The flaps were sutured to allow a fully submerged healing. The surgery on the other side of the mandible and the sacrifices were planned in such a way to obtain biopsies representing the healing after 1, 2, 4, and 8 weeks (n = 6 per period). RESULTS: After one week of healing, new bone apposition was found at both surfaces with percentages of 6.9 ± 3.3% and 6.1 ± 4.6% at UnicCa(®) and SLActive(®), respectively. After 2 weeks, the percentages had increased to 29.1 ± 11.9% and 21.6 ± 14.3%, respectively. After 4 and 8 weeks of healing, mean values of 46.3 ± 7.3% and 58.7 ± 15.1% at UnicCa(®) and 51.2 ± 16.1% and 68.9 ± 15.4% at SLActive(®) surfaces were found, respectively. None of the differences in percentages were statistically significant. Concomitantly, the old bone was resorbed at both surfaces from about 21-22% after 1 week to about 4-6% after 8 weeks of healing. CONCLUSIONS: The osseointegration process onto moderately rough titanium implant surfaces of high hydrophilicity was very similar for two implant systems that were both nanotechnologically modified.

Sequential Healing at Calcium- versus Calcium Phosphate-Modified Titanium Implant Surfaces: An Experimental Study in Dogs.

PURPOSE: The aim of this paper was to study the sequential healing of bone tissues at implants with different configuration and different modified surfaces. MATERIALS AND METHODS: Twelve Beagle dogs were used. Extractions of all teeth from the second premolar to the first molar were performed in both sides of the mandible. After 3 months, full-thickness flaps were elevated and two implants of different systems and with different surfaces were randomly installed in the premolar region in one side of the mandible. One surface was acid etched and further modified with calcium ions (BTI unicCa®), the other was sandblasted and acid etched plus a nanometer calcium phosphate deposition (3i T3®). The flaps were sutured to allow a fully submerged healing. The surgery on the other side of the mandible and the sacrifices were planned in such a way to obtain biopsies representing the healing after 1, 2, 4, and 8 weeks (n = 6 per period). RESULTS: After 1 and 2 weeks of healing, the mean values of new bone apposition on the implant surfaces were 5.9 ± 3.3% and 29.8 ± 16.0% at BTI unicCa and 4.6 ± 3.3% and 12.4 ± 5.6% at 3i T3, respectively. After 4 and 8 weeks, the percentage increased, being 49.4 ± 8.1% and 63.6 ± 7.3% at BTI unicCa and 40.3 ± 10.0% and 47.3 ± 20.2 at 3i T3, respectively. Differences statistically significant between the two surfaces were found only at the 2- and 4-week observation periods. Concomitantly, the old bone was resorbed at both surfaces from about 15-17% after 1 week to about 4-6% after 8 weeks of healing. CONCLUSION: Moderately rough surfaces modified with calcium ions or discrete calcium phosphate nanocrystalline deposition showed similar patterns of sequential healing. Higher new bone percentages were found at BTI unicCa compared with the 3i T3 implants, the difference being statistically significant at 2 and 4 weeks observation.

Healing at implant sites prepared conventionally or by means of Sonosurgery ®. An experimental study in dogs.

OBJECTIVE: To compare peri-implant tissue healing at implants installed in sites prepared with conventional drills or a sonic device. MATERIAL AND METHODS: In six Beagle dogs, the mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness muco-periosteal flaps were elevated and recipient sites were prepared in both sides of the mandible. In the right side (control), the osteotomies were prepared using conventional drills, while, at the left side (test), a sonic device (Sonosurgery(®)) was used. Two implants were installed in each side of the mandible. After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. RESULTS: The time consumed for the osteotomies at the test was more than double compared to the conventional control sites. No statistically significant differences were found for any of the histological variables evaluated for hard and soft tissue dimensions. Although not statistically significant, slightly higher mineralized bone-to-implant contact was found at the test (65.4%) compared to the control (58.1) sites. CONCLUSIONS: Similar healing characteristics in osseointegration and marginal hard tissue remodeling resulted at implants installed into osteotomies prepared with conventional drills or with the sonic instrument (Sonosurgery(®)).

On the Early Mechanisms of Bone Formation after Maxillary Sinus Membrane Elevation: An Experimental Histological and Immunohistochemical Study.

BACKGROUND: Previous studies have shown predictable bone formation in the maxillary sinus after membrane elevation. However, how and where the bone is formed is not well understood. PURPOSE: The aim of the study was to histologically and immunohistochemically study the early bone formation events in primates after membrane elevation in the maxillary sinus. MATERIALS AND METHODS: Nine adult male tufted capuchin primates (Cebus apella) were included in the study. Eight animals were subjected to bilateral maxillary sinus membrane elevation using a lateral replaceable bone window technique. One oxidized dental implant was placed into the maxillary sinus cavity on both sides. In four animals, one sinus was left without any additional treatment, whereas the contralateral sinus was filled with autologous bone grafts from the tibia. In two animals, the implants were inserted under the elevated sinus membrane on both sides. In two animals, the sinus membrane was totally removed. The animals were euthanized after 10 or 45 days. One nonoperated animal representing pristine tissue conditions served as control. The maxillary sinuses with implants were retrieved and further processed for light microscopic ground sections or decalcified sections for immune-histochemical analyses. RESULTS: Bone formation started from the bottom of the sinus floor, sprouting into the granulation tissue along the implant surface under the elevated membrane irrespective of time and surgical technique. Bone formation was not seen in direct conjunction with the sinus membrane. A distinct expression of osteopontin was observed in the serous glands of the lamina propria close to the implant within all groups. CONCLUSION: Bone formation after sinus membrane elevation with or without additional bone grafts starts at the sinus floor and sprouts into the elevated space along the implant surface. The sinus membrane does not seem to present osteoinductive potential in sinus membrane elevation procedures in this study.

Sub-crestal positioning of implants results in higher bony crest resorption: an experimental study in dogs.

OBJECTIVE: To compare peri-implant soft- and hard-tissue integration at implants installed juxta- or sub-crestally. Furthermore, differences in the hard and soft peri-implant tissue dimensions at sites prepared with drills or sonic instruments were to be evaluated. MATERIAL AND METHODS: Three months after tooth extraction in six dogs, recipient sites were prepared in both sides of the mandible using conventional drills or a sonic device (Sonosurgery(®)). Two implants with a 1.7-mm high-polished neck were installed, one with the rough/smooth surface interface placed at the level of the buccal bony crest (control) and the second placed 1.3 mm deeper (test). After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation. RESULTS: The buccal distances between the abutment/fixture junction (AF) and the most coronal level of osseointegration (B) were 1.6 ± 0.6 and 2.4 ± 0.4 mm; between AF and the top of the bony crest (C), they were 1.4 ± 0.4 and 2.2 ± 0.2 mm at the test and control sites, respectively. The top of the peri-implant mucosa (PM) was located more coronally at the test (1.2 ± 0.6 mm) compared to the control sites (0.6 ± 0.5 mm). However, when the original position of the bony crest was taken into account, a higher bone loss and a more apical position of the peri-implant mucosa resulted at the test sites. CONCLUSIONS: The placement of implants into a sub-crestal location resulted in a higher vertical buccal bone resorption and a more apical position of the peri-implant mucosa in relation to the level of the bony crest at implant installation. Moreover, peri-implant hard-tissue dimensions were similar at sites prepared with either drills or Sonosurgery(®).

Short-term evaluation of grafts fixed with either N-butyl-2-cyanocrylate or screws.

PURPOSE: N-butyl-2-cyanoacrylate (NB-Cn) is an alternative method for onlay graft fixation and might be efficient for preserving the graft volume. Our aim was to analyze the gene expression and mineralized tissue variations of calvarial bone grafting fixed in the mandible with either NB-Cn or a titanium screw (TiS). MATERIALS AND METHODS: New Zealand rabbits had bilateral calvarial grafts fixed at both sides of the mandible with either NB-Cn or a TiS. The rabbits were sacrificed at 4 and 8 days, and micro-computed tomography analysis was performed. For molecular analysis, the gene expression of interleukin-6, interleukin-10, and tumor necrosis factor-α was assessed. Quantification using real-time polymerase chain reaction was performed. Statistical analysis was performed using the paired Student t test (P < .05). RESULTS: Bone graft fixation with NB-Cn promoted superior volume and density preservation. The percentage of mineralized tissue at the center portion and border of the graft was very similar (NB-Cn, 50.6% ± 8.3% and 50.3% ± 10.6%, respectively) and superior than in the TiS group (32.5% ± 3.5% and 33.8% ± 6%, respectively). Genes from the NB-Cn group were upregulated compared with those in the TiS group at the initial phases of bone healing (4 days), with the profile reversed at the 8-day point. At day 8, the osteoclastogenesis-related genes were upregulated in the TiS group. CONCLUSIONS: Onlay bone grafts fixed with screws induced more inflammation during the initial remodeling process than did NB-Cn. The differences in the incorporation into the host bed suggest that the use of adhesives for graft fixation will promote superior volume and density preservation.

Deproteinized bovine bone mineral particles and osseointegration of implants without primary bone contact: an experimental study in dogs.

OBJECTIVES: To evaluate the influence on osseointegration of Deproteinized bovine bone mineral (DBBM) particles used to fill defects of at least 1 mm around implants having no primary contact with bone. MATERIAL AND METHODS: Premolars and first molars were extracted bilaterally from the mandible of six Labrador dogs. After 3 months of healing, mucoperiosteal full-thickness flaps were elevated, and one recipient site was prepared in the molar region of each hemi-mandible to place implants. These were installed with a deliberate circumferential and periapical space to the bone walls of 1.2 mm. All implants were stabilized with passive fixation plates to maintain the implants in situ and without any contact with the implant bed. The control sites were left to be filled with coagulum, while at the test sites, the residual gap was filled with DBBM. After 3 months of submerged healing, the animals were sacrificed. Ground sections were prepared and analyzed histomorphometrically. RESULTS: Mineralized bone-to-implant contact was 4.0% and 3.9% for control and test sites, respectively. The width of the residual defects was 0.48 mm and 0.88 mm at the control and test sites, respectively. The percentage of implant surface covered by a layer of dense connective tissue of 0.12 mm of width on average was 84.9% and 88.5% at the control and test sites, respectively. CONCLUSION: A minor and not predictable degree of contact or distance osteogenesis was obtained on the implant surface when primary contact of the implant surface with the implant bed had deliberately been avoided. DBBM grafting of the artificial gap did not favor osseointegration. Neither did it enhance the ability to bridge the gap with newly formed bone in an artificial defect wider than 1 mm.

Comparisons between Bio-Oss(®) and Straumann(®) Bone Ceramic in immediate and staged implant placement in dogs mandible bone defects.

OBJECTIVE: To compare immediate and staged approach implant placement in circumferential defects treated with deproteinized bovine bone mineral (DBBM); hidroxyapatite/tricalcium phosphate (HA/TP); autogenous bone (Ab); and coagulum (Cg); upon implant stability, osseointegration and alveolar crest maintenance. MATERIALS AND METHODS: Six dogs underwent extractions of lower premolars, bilaterally. Twelve weeks later four bone defects (6 mm wide/4 mm long) were drilled at one side and randomly filled with DBBM; HA/TP; Ab; and Cg, respectively, and left to heal (staged approach). Eight weeks later one implant (Osseospeed(™) , AstraTech) was placed in experimental sites. At the same session four defects were drilled on contra-lateral side and implants were inserted immediately after biomaterials grafting (immediate approach). Animals were euthanized 8 weeks later. Implant stability was measured by resonance frequency analysis (RFA) at installation and after sacrifice. Ground sections were prepared for bone contact (BIC); bone area (BA); distance implant shoulder-bone crest (IS-C); distance implant shoulder first bone contact (IS-B); and areas occupied by soft tissue. RESULTS: The BA and BIC were superior in the staged approach. The Cg exhibited higher BIC and BA as compared with other materials at the total implant body (P = 0.004 and 0.012, respectively). The DBBM, HA/TP and Ab groups rendered similar BA and BIC. The immediate approach resulted in less crest resorption compared to staged approach. The biomaterials did not affect the IS-C and IS-B measurements. Particles area tended to be higher in DBBM group than HA/TP (P = 0.15), while soft tissue infiltrate was higher in DBBM group when used in the immediate approach (P = 0.04). The RFA indicated gain in stability in the staged approach (P = 0.002). The correlation test between RFA vs. BIC and BA demonstrated inferior stability for DBBM group in immediate approach (P = 0.01). CONCLUSIONS: Implants placed in healed defects resulted in better stability as a consequence of higher BIC and BA. The Cg alone rendered increased BIC compared to other materials in both approaches. Immediate approach should be preferable to staged approach in terms of alveolar crest maintenance. The BIC and BA values did not vary between micro and macro-threads in this experimental model. Implants installed in sites filled with DBBM in immediate approach were less stable.

Determination of relative in vivo osteoconductivity of modified potassium fluorrichterite glass-ceramics compared with 45S5 bioglass.

Potassium fluorrichterite (KNaCaMg(5)Si(8)O(22)F(2)) glass-ceramics were modified by either increasing the concentration of calcium (GC5) or by the addition of P(2)O(5) (GP2). Rods (2 × 4 mm) of stoichiometric fluorrichterite (GST), modified compositions (GC5 and GP2) and 45S5 bioglass, which was used as the reference material, were prepared using a conventional lost-wax technique. Osteoconductivity was investigated by implantation into healing defects in the midshaft of rabbit femora. Specimens were harvested at 4 and 12 weeks following implantation and tissue response was investigated using computed microtomography (µCT) and histological analyses. The results showed greatest bone to implant contact in the 45S5 bioglass reference material at 4 and 12 weeks following implantation, however, GST, GC5 and GP2 all showed direct bone tissue contact with evidence of new bone formation and cell proliferation along the implant surface into the medullary space. There was no evidence of bone necrosis or fibrous tissue encapsulation around the test specimens. Of the modified potassium fluorrichterite compositions, GP2 showed the greatest promise as a bone substitute material due to its osteoconductive potential and superior mechanical properties.

Evaluation of osteoconductive and osteogenic potential of a dentin-based bone substitute using a calvarial defect model.

The aim of this study was to assess the osteoconductive and osteogenic properties of processed bovine dentin using a robust rabbit calvarial defect model. In total, 16 New Zealand White rabbits were operated to create three circular defects in the calvaria. One defect was left unfilled, one filled with collected autogenous bone, and the third defect was filled with the dentin-based bone substitute. Following surgery and after a healing period of either 1 or 6 weeks, a CT scan was obtained. Following sacrificing, the tissues were processed for histological examination. The CT data showed the density in the area grafted with the dentin-based material was higher than the surrounding bone and the areas grafted with autologous bone after 1 week and 6 weeks of healing. The area left unfilled remained an empty defect after 1 week and 6 weeks. Histological examination of the defects filled with the dentin product after 6 weeks showed soft tissue encapsulation around the dentin particles. It can be concluded that the rabbit calvarial model used in this study is a robust model for the assessment of bone materials. Bovine dentin is a biostable material; however, it may not be suitable for repairing large 4-wall defects.

Osteogenesis at implants without primary bone contact - an experimental study in dogs.

AIM: To evaluate the healing at implants with a moderately rough surface placed and stabilized in recipient sites of dimensions deeper and larger than that of the implants to avoid any contact between parent bone and the implant. MATERIAL & METHODS: In six Labrador dogs, premolars and first molars were extracted bilaterally in the mandible. After 3 months of healing, mucoperiosteal full-thickness flaps were elevated and the premolar area of the alveolar bony crest was selected. Three recipient sites were prepared to place three implants. One implant was used as control. The other two were placed in recipient sites which left a circumferentially and periapical prepared defect of 0.7 mm (small) and 1.2 mm (large), respectively. All implants were stabilized with passive fixation plates to maintain the implants stable and without any contact with the implant bed. After 3 months of submerged healing, the animals were sacrificed. Ground sections were prepared and analyzed histomorphometrically. RESULTS: The BIC% was 5.3% and 0.3% for implants placed in small and large defect sites, respectively, whereas it was 46.1% for control implants. The differences were statistically significant. The width of the residual defects was 0.4 and 0.5 mm at the small and large defects, respectively. An approximately 0.09 mm layer of dense connective tissue (DCT) rich in fibers and fibroblast-like cells was observed adherent to the implant surfaces. The percentage of implant surface covered by DCT was 92.8% and 95.6% at the small and large defects, respectively. CONCLUSION: Osseointegration was observed at the test sites, and the dimensions of the defects influenced the outcomes. However, the degree of osseointegration at both small and large defects was very low compared with the control sites.

Use of a titanium device in lateral sinus floor elevation: an experimental study in monkeys.

AIM: To evaluate the effect of a space-maintaining device fixed to the lateral wall of the maxillary sinus after the elevation of the sinus mucosa on bone filling of the sinus cavity. MATERIAL AND METHODS: Immediately after the elevation of the maxillary sinus Schneiderian membrane accomplished through lateral antrostomy in four monkeys, a titanium device was affixed to the lateral sinus wall protruding into the sinus cavity to maintain the mucosa elevated without the use of grafting material. The healing of the tissue around the implants was evaluated after 3 and 6 months. Ground sections were prepared and analyzed histologically. RESULTS: The void under the elevated sinus membrane, originally filled with the blood clot, was reduced after 3 as well as after 6 months of healing of about 56% and 40.5%, respectively. In seven out of eight cases, the devices had perforated the sinus mucosa. The formation of mineralized bone and bone marrow amounted to about 42% and 69% after 3 and 6 months, respectively. The connective tissue represented about 53% and 23% of the newly formed tissue after 3 and 6 months, respectively. CONCLUSIONS: New bone formation was found below the devices. However, shrinkage of the newly formed tissue was observed both after 3 and 6 months of healing. Hence, the space-maintaining function of the devices used in the present study has to be questioned.

Healing outcomes at implants installed in grafted sites: an experimental study in dogs.

AIM: To evaluate the integration of implants installed using a surgical guide in augmented sites with autologous bone or deproteinized bovine bone mineral (DBBM) blocks, concomitantly with a collagen membrane. MATERIAL AND METHODS: Mandibular molars were extracted bilaterally in six Labrador dogs, the buccal bony wall was removed, and a box-shaped defect was created. After 3 months, flaps were elevated, a bony graft was harvested from the ascending ramus, and secured to the lateral wall of the defect by means of screws. In the left mandibular side, a DBBM block was fixed into the defect. A resorbable membrane was applied at both sides, and the flaps were sutured. After 3 months, flaps were elevated, and a customized device was used as surgical guide to prepare the recipient sites in the interface between grafts and parent bone. One implant was installed in each side of the mandible. After 3 months, biopsies were harvested, and ground sections were prepared for histologic evaluation. RESULTS: One autologous bone block graft was lost before implant installation. The width of the alveolar crest at the test sites (DBBM) was 5.4 ± 1.2 mm before, 9.4 ± 1.2 mm immediately after grafting, and 9.3 ± 1 mm at implant installation. At the control sites (autologous bone), the corresponding values were: 5.2 ± 1, 9 ± 1.2, and 8.7 ± 0.9 mm, respectively. All implants installed were available for histologic evaluation (n = 5). The autologous bone grafts, rich in vessels and cells, were integrated in the parent bone, and only little non-vital bone was found. The BIC% was 56.7 ± 15.6% and 54.2 ± 13.2% at the buccal and lingual aspects, respectively. At the test sites, the DBBM appeared to be embedded into connective tissue, and very little newly formed bone was encountered within the grafts. The BIC% was 5.8 ± 12.3% and 51.3 ± 14.2% at the buccal and lingual aspects, respectively. CONCLUSIONS: Autologous bone blocks used to augment the alveolar bony crest horizontally allowed the complete osseointegration of implants installed after 3 months of healing. However, similar blocks of DBBM did not promote osseointegration, although the installed implants were stable owing to the osseointegration in the sites of the parent bone.

Role of teeth adjacent to implants installed immediately into extraction sockets: an experimental study in the dog.

AIM: To evaluate the influence of the presence of both adjacent teeth on the level of alveolar bony crest at sites where implants were installed into the socket immediately after tooth extraction. MATERIAL AND METHODS: Six Labrador dogs were used. Extractions of all teeth from the second premolar to the first molar were performed in the right side of the mandible, after full-thickness flap elevation. In the left side of the mandible, an endodontic treatment of the mesial root of the third and fourth premolars was performed. Full-thickness flaps were elevated, the teeth hemi-sected, and the distal roots removed. Immediately after, implants were bilaterally installed with the margin flush to the buccal bony crest. The implants were placed in the center of the alveolus at the third premolars and toward the lingual bony plate of the alveolus at the fourth premolars. After 3 months of healing, the animals were euthanized. RESULTS: All implants were integrated in mature bone. More bone resorption was observed at the test compared to the control sites. At the buccal aspect, a resorption of 2.8 ± 0.5 and 1.6 ± 0.4 mm at the third premolars and of 2.4 ± 0.6 and 0.8 ± 0.7 mm at the fourth premolars were found, at the test and control sites, respectively. At the lingual aspect, the bony crest was apically located in relation to the implant shoulder 1.5 ± 0.3 and 0.5 ± 0.5 mm at the third premolars and 1.6 ± 0.6 and 0.3 ± 1.1 mm at the fourth premolars, at the test and control sites, respectively. A lower buccal bone resorption was found at the control implants placed lingually. CONCLUSION: Multiple extractions of teeth adjacent to a socket into which implants were installed immediately after, tooth extraction induced more alveolar bone recession compared to sites where the adjacent teeth were preserved. Moreover, an implant placed more lingually yielded less recession of the buccal aspect of the implant.

Avanços e desafios da pesquisa básica aplicada em Implantodontia / Advances and challenges of the basic research applied to Implantology

A Implantodontia revolucionou a Odontologia moderna e se tornou a primeira opção de tratamento reabilitador para os casos de desdentados parciais ou totais. Nesse processo, os avanços tecnológicos e científicos da técnica proporcionaram níveis de sucesso próximos a 100% e com alta previsibilidade. Apesar dos grandes avanços, ainda temos desafios em pontos específicos, como desenho dos implantes, biofuncionalização da superfície do implante, manutenção do nível ósseo e terapias previsíveis para implantes com perda óssea peri-implantar progressiva. Atualmente, busca-se ampliar as possibilidades de indicações dos implantes para além dos casos tecnicamente favoráveis, reduzindo-se o tempo de cicatrização e de carregamento do implante, bem como reestabelecendo um padrão estético que mimetiza a dentição natural com previsibilidade, estabilidade e saúde por tempo indeterminado

Implantology revolutionized the modern dentistry and became the first choice in the rehabilitation of partially dentate or edentulous patients. During this process, technologic and scientific advances granted success rate up to 100% with high predictability. Despite the great advances, we are still facing specific key challenges regarding implant design, surface biofunctionalization, bone level preservation and predictable therapies to deal with progressive cervical bone loss. Currently, new possibilities have been explored to expand dental implant treatment for those cases further than the ideal condition, achieving reduced healing and loading times, and also to reconstruct an aesthetic profile mimicking the natural dentition together with confidence, stability, and long-term healthiness.