Xenografts Supplemented with Pamindronate placed in postextraction sockets to avoid crestal bone resorption. Experimental study in Fox hound dogs.

OBJECTIVES: The aim of the study was to compare the effects of porcine xenografts (MP3(®)) with or without pamindronate for the healing of small and large defects of postextraction sockets. MATERIALS AND METHODS: Six beagle dogs were used in the study; second premolars and first molars of the mandible were extracted, small defects (SD) and large defects (LD) were identified. Each defect was measured and randomly filled as follows: SC (small control defects filled with MP3(®) alone), ST (small test defects filled with MP3(®) modified with pamindronate), LC (large control defects filled with MP3(®) alone), LT (large test defects filled with MP3(®) modified with pamindronate). After 4 and 8 weeks, the animals were euthanized and the percentages of new bone formation (NB), residual graft (RG) and connective tissue (CT) were analysed by histology and histomorphometry of undecalcified samples. RESULTS: After 4 weeks, NB formation was higher for ST compared to all groups and for LT compared to LC (P < 0.05); RG was significantly higher in both control groups compared to tests (P < 0.05); and CT was higher in large defects (LC and LT) compared to small defects. After 8 weeks, NB formation was higher for test groups (ST and LT) compared to controls (P < 0.05); RG was significantly higher in both control groups compared to tests (P < 0.05); and CT was higher in large defects (LC and LT) compared to small defects (P < 0.05). CONCLUSIONS: Within the limitations of this experimental study, the findings suggest that porcine xenografts modified with pamindronate favours the new bone formation and increased the porcine xenograft substitution/replacement after 4 and 8 weeks of healing.

Human fetal osteoblast behavior on zirconia dental implants and zirconia disks with microstructured surfaces. An experimental in vitro study.

OBJECTIVES: To measure the lateral surface area of microgrooved zirconia implants, to evaluate the cell geometry and cell density of human fetal osteoblasts seeded on zirconia microgrooved implants, to describe the surface roughness and chemistry, and to evaluate the activity of human fetal osteoblasts seeded on zirconia microgrooved disks. MATERIALS AND METHODS: This experimental in vitro study used 62 zirconia implants and 130 zirconia disks. Two experimental groups were created for the implants: 31 non-microgrooved implants (Control) and 31 microgrooved implants (Test); two experimental groups were created for the disks: 65 non-microgrooved disks (Control) and 65 microgrooved disks (Test). The following evaluations of the implants were made: lateral surface area (LSA), cell morphology, and density of human fetal osteoblasts seeded on implant surfaces. On the disks, surface parameters (roughness and chemistry) and cell activity (alkaline phosphatase - ALP and alizarin red - ALZ) were evaluated at 7 and 15 days. RESULTS: LSA was lower for control implants (62.8 mm) compared with test implants (128.74 mm) (P < 0.05). Cell bodies on control surfaces were flattened and disorganized, while in the test group, they were aligned inside the microgrooves. Control group cells showed few lamellipodia, which were attached mainly inside topographical accidents (surface cracks, valleys, and pits). Test group implants presented cells rich in lamellipodia prolongations, attached to the inner walls or to the borders of the microgrooves and in the flat areas between the microgrooves. Cell density was higher in the test group compared with controls (P < 0.05) Surface roughness and oxygen content increased in test disks samples compared with controls (P < 0.05). Carbon and aluminum were reduced in disks test samples compared with controls (P < 0.05), and ALP and ALZ levels were significantly increased on test surfaces (P < 0.05) at both study times. CONCLUSIONS: Within the limitations of this experimental study, it may be concluded that (i) Roughness is increased and chemical composition enhanced on the surface of zirconia implants with microgrooves. (ii) The LSA of microgrooved zirconia implants is greater and provides more available surface compared with implants of the same dimensions without microgrooves. (iii) Microgrooves on zirconia implants modify the morphology and guide the size and alignment of human fetal osteoblasts. (iv) Zirconia surfaces with microgrooves of 30 µm width and 70 µm separation between grooves enhance ALP and ALZ expression by human fetal osteoblasts.

Zirconia with laser-modified microgrooved surface vs. titanium implants covered with melatonin stimulates bone formation. Experimental study in tibia rabbits.

OBJECTIVES: The aim of the study was to evaluate if zirconia implants with micro-grooved surfaces supplemented with melatonin enhance the bone-to-implant contact (BIC) vs. titanium implants with the same coating. MATERIALS AND METHODS: Eighty implants divided in four groups were inserted in the tibia of 20 New Zealand rabbits as follows: (group A) 20 titanium implants; (group B) 20 micro-grooved zirconia implants; (group C) 20 titanium implants supplemented with melatonin and (group D) 20 micro-grooved zirconia implants supplemented with melatonin. Histometric and SEM evaluation of BIC were evaluated after 1 and 4 weeks. RESULTS: At 1 week, group C (29.7 ± 2.4%) and group D (28.9 ± 1.3%) implants showed higher BIC% compared with group A and B (P < 0.05). After 4 weeks, group D showed higher BIC compared with all the groups (47.5 ± 2.2%) (P < 0.05). Also Connective tissue was higher in groups B (78.9 ± 2.1%) and D (88.7 ± 1.2%) related to titanium and zirconia melatonin untreated at 4 weeks (P < 0.05). CONCLUSIONS: Within the limitations of this pilot study in rabbits, we can conclude that the local application of melatonin increases the BIC values in titanium and in zirconia implants at 1 week.

New bone formation in bone defects after melatonin and porcine bone grafts: experimental study in rabbits.

OBJECTIVE: The aim of this study was to evaluate the effect of the topical application of melatonin compared with collagenized porcine bone grafts to accelerate bone formation 2 months after their insertion in tibiae rabbits. MATERIAL AND METHODS: Twenty New Zealand rabbits weighing 3,900-4,500 g were used. Twenty collagenized porcine bone (MP3) grafts, twenty melatonin-impregnated bone grafts, and twenty control areas were placed in the proximal metaphyseal area of both rear tibias. Four groups were formed according to the moment in which animal killing was carried out: Group I (15 days), Group II (30 days), Group III (45 days) and Group IV (60 days). Cortical width and cortical length of bone formation was measured. Following implantation, an anteroposterior and lateral radiological study was carried out. Samples were sectioned at 5 µm and stained using hematoxylin-Eeosin, Masson's trichromic, and Gordon-Switt reticulin stains. RESULTS: After 60 days of treatment period, melatonin increased the length of cortical bone formation 99.03 ± 0.61% like control 98.90 ± 3.82% compared with porcine bone 92.73 ± 1.08%. Related to perimeter of cortical bone of the tibiae melatonin new bone was 98.35 ± 1.14% like control 98.0 ± 1.43% more than porcine bone 92.05 ± 1.03%. Histomorphometric values related to porcine bone were connective tissue 49.16 ± 2.4%, graft material (MP3) 23.52 ± 2.3%, and new bone formation 27.32 ± 1.4% compared with test group with melatonin 24.5 ± 1.2%, connective tissue 45.1 ± 1.2%, and new bone formation of 30.4 ± 1.0%. CONCLUSION: Melatonin has proven to regenerate the width and length of cortical bone in tibiae rabbits more quickly than collagenized porcine bone. Melatonin acts as a bone stimulator compared with porcine bone and control sites.

Porous titanium granules in critical size defects of rabbit tibia with or without membranes.

Recently, porous titanium granules (PTGs) have been indicated for the preservation of the dimensions of post-extraction sockets, as a filler in sinus lift procedures and for the treatment of peri-implant and periodontal defects, based on the osteoconductivity and dimensional stability of the titanium granules. However, there is a lack of information regarding the use of this material in larger defects and in conjunction with membranes. The objective of this study is to test the behavior of PTGs used to fill critical size defects in rabbit tibiae, with and without membranes. Critical defects were created in both tibiae of rabbits, divided randomly into three groups: Group A (defect filled with PTG), Group B (defect filled with PTG+collagen membrane) and a control group (empty defect). After six weeks, histomorphometric analysis was performed. The results showed more defect closures at the cortical area (87.37%±2.2%) and more bone formation at the marrow area (57.6%±1.3%) in Group B, in comparison with the other groups (P<0.05); the use of membranes improved the material stability expressed as more percentages of the original material when membranes were used (P<0.05). Finally, inflammatory reactions were observed when the granules were not protected by membranes. In spite of the limitations of this animal study, it may be concluded that PTG particles are osteoconductive and allow bone growth. The PTG particles must be covered by a membrane, especially when grafting larger defects, in order to control particle migration, promote clot stabilization and separate the PTG graft from undesired soft tissue cells.

Crestal bone loss related to immediate implants in crestal and subcrestal position: a pilot study in dogs.

OBJECTIVES: The aim of the present study was to compare crestal bone loss with different implant designs inserted immediately in crestal or subcrestal position in post-extraction sockets in a dog model. MATERIALS AND METHODS: The mandibular second, third, fourth premolars, and the first molars of six adult fox hound dogs were extracted bilaterally, and 48 implants were placed immediately in both hemi-arches of each dog. Randomly, eight implants (sky classic (®) and blue sky (®) ) were inserted, four crestally (control group) and four 2 mm subcrestally (test group). Both groups were treated with a minimal mucoperiosteal flap elevation approach. After a 12-week healing period, the animals were sacrificed, and samples were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out to compare buccal and lingual bone height loss. RESULTS: All implants were clinically and histologically osseointegrated. Healing patterns examined microscopically at eight and 12 weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. At 12 weeks, the distance from the top of the implant collar to the first BIC (ISBc) showed significant difference between implant positions (crestal or subcrestal) in the buccal aspect (P = 0.1253), values for the crestal group being higher (1.79 ± 0.3 mm) in comparison with the subcrestal group (0.89 ± 0.5 mm). Better results were achieved by both implant designs when implants were placed in the deeper position. No significant differences were found in BIC values (P > 0.05). The total BIC at 8 weeks was (46.22 ± 4.29%) for the crestal group and (49.72 ± 2.21%) for the subcrestal group; at 12 weeks, it was (41.54 ± 3.87%) for the crestal group and (56.87 ± 3.46%) for the subcrestal group. CONCLUSIONS: Within the limitations of this study, the findings suggest that apical positioning of the top of the implant does not jeopardize bone crest and peri-implant tissue remodeling. However, less resorption of the lingual and buccal crest may be expected when implants are placed 2 mm subcrestally, but this is not related to implant design. Moreover, implants placed subcrestally produced better bone-to-implant contact measurements.

Histologic and histomorphometric behavior of microgrooved zirconia dental implants with immediate loading.

PURPOSE: The study aims to assess the total soft tissue (ST) width, crestal bone level (CBL), bone-to-implant contact (BIC), and bone density (BD) for zirconia implants textured with microgrooved surfaces and immediately loaded. MATERIALS AND METHODS: This study included 51 implants; one implant from each study group was retained for surface characterization. The 48 remaining implants were inserted randomly in premolar areas of both sides of the healed edentulous lower jaws of foxhound dogs. They were divided into three groups of 16: control (titanium); test A (zirconia), and test B (microgrooved zirconia). The implants were splinted and covered with an acrylic bridge. A split-mouth design was used and immediate occlusal loading was applied on one side, while the other side did not have occlusal contact. ST, CBL, BIC, and BD were evaluated after 3 months. The effects of immediate loading on these parameters were analyzed. RESULTS: All the implants were osseointegrated. ST was established at 3 months with mean values of 2.9 ± 0.4 mm for all groups. No differences were appreciated between loaded and unloaded sides regarding ST (p > .05). CBL showed a mean of 1.2 ± 0.3 mm for all groups without differences between loaded and unloaded sides (p > .05). BIC percentages were significantly higher for loaded all-microgrooved implants (p < .05). BD percentages were higher in areas close to all-microgrooved implants (p < .05) and significantly higher for loaded implants than unloaded. CONCLUSIONS: Within the limitations of the present study, it may be concluded that for zirconia dental implants with microgrooved surfaces and immediate loading, the thickness of STs remains stable resulting in 3 mm mean biologic width, that crestal bone preservation is related to insertion depth, and that higher BIC percentages and increased BD around implants microgrooved over the entire intraosseous area may be expected at 3 months following implant insertion and immediate loading.

Biomechanical and histological evaluation of four different titanium implant surface modifications: an experimental study in the rabbit tibia.

OBJECTIVES: This study presents a biomechanical comparison of bone response to commercially pure titanium screws with four different types of surface topographies placed in the tibial metaphysis of 30 rabbits. MATERIALS AND METHODS: One hundred twenty implants were tested double-blinded: (a) blasted, acid-etched, and discrete crystal deposition (DCD), (b) blasted, (c) acid-etched, and (d) blasted and acid-etch. Resonance frequency analysis (RFA/ISQ), reverse torque values (RTV), and bone-to-implant contact (BIC) were measured at the time of implant insertion (day 0), 15, 28, and 56 days of healing. RESULTS: All groups tested demonstrated increased RFA/ISQ and RTV results over the time course. At 15 days, the blasted, acid-etched, and DCD group demonstrated a non-significant trend toward higher values when compared to the blasted and etched group (33.0 ± 16 vs. 26.3 ± 12 Ncm, p = .16). At 56 days, the groups utilizing blasting to create additional surface roughness (Sa > 1 micron) showed a statistical significant difference in RTQ versus the non-blasted group (38.5 ± 14 vs. 29.5 ± 9 Ncm, p = .03). CONCLUSIONS: Within the limitations of this study, only the increase in surface roughness (Ra > 1) at 56 days demonstrated statistically significant effects on RTQ. Other additional surface features, such as sub-micron scale DCD, demonstrated improved healing trends but without significance for clinical applications.

Implant stability and marginal bone level of microgrooved zirconia dental implants: A 3-month experimental study on dogs.

BACKGROUND/AIM: The modification of implant surfaces could affect mechanical implant stability as well as dynamics and quality of peri-implant bone healing. The aim of this 3-month experimental study in dogs was to investigate implant stability, marginal bone levels and bone tissue response to zirconia dental implants with two laser-micro-grooved intraosseous surfaces in comparison with nongrooved sandblasted zirconia and sandblasted, high-temperature etched titanium implants. METHODS: Implant surface characterization was performed using optical interferometric profilometty and energy dispersive X-ray spectroscopy. A total of 96 implants (4 mm in diameter and 10 mm in length) were inserted randomly in both sides of the lower jaw of 12 Fox Hound dogs divided into groups of 24 each: the control (titanium), the group A (sandblasted zirconia), the group B (sandolasted zirconia plus microgrooved neck) and the group C (sandblasted zirconia plus all microgrooved). All the implants were immediately loaded. Insertion torque, periotest values, radiographic crestal bone level and removal torque were recorded during the 3-month follow-up. Qualitative scanning electon microscope (SEM) analysis of the bone-implant interfaces of each group was performed. RESULTS: Insertion torque values were higher in the group C and control implants (p < 0.05). Periotest values increased in all the periods in proportion to the extent of microgrooving as follows: the group C > the control > the group B > the group A (p < 0.05). Radiographic measurements showed minimal crestal bone loss at 3 months for microgrooved zirconia implants (groups C and B) and control implants compared with the group A implants (p < 0.05). The removal torque values increased with time for all the groups as follows: the group C > the control > the group B > the group A (p < 0.05). SEM showed that implant surfaces of the groups B and C had an extra bone growth inside the microgrooves that corresponded to the shape and direction of the microgrooves. CONCLUSION: The addition of microgrooves to the entire intraosseous surface of zirconia dental implants enhances primary and secondary implant stability, promotes bone tissue ingrowth and preserves crestal bone levels.

Calculation of bone graft volume using 3D reconstruction system

Objectives: To obtain bone “bioreplicas” for determining precisely the amount of biomaterial required for boneregeneration procedure. Study design: A case-control comparison with a total sample size of 20 cases, 10 controland 10 test samples. “Bioreplicas” were generated from helical CAT scans with 0.5 mm slices, without 3Dreconstruction or image filters. Bone defects in premolar and molar areas were treated with titanium mesh andxenograft (MP3) combined with resorbable carriers. Time taken to carry out procedures with and without the useof “bioreplicas” (in minutes), discrepancies between the grafts performed with and without “bioreplicas” and bonedefects (mm), and postoperative complications were registered. Results: No significant differences were recordedfor measurements of width and length of bone defect between patient bone and the biological models. Conclusions:The use of “bioreplicas” obtained by rapid prototyping is effective in treatment planning (AU)

Calculation of bone graft volume using 3D reconstruction system.

OBJECTIVES: To obtain bone bioreplicas for determining precisely the amount of biomaterial required for bone regeneration procedure. STUDY DESIGN: A case-control comparison with a total sample size of 20 cases, 10 control and 10 test samples. Bioreplicas were generated from helical CAT scans with 0.5 mm slices, without 3D reconstruction or image filters. Bone defects in premolar and molar areas were treated with titanium mesh and xenograft (MP3) combined with resorbable carriers. Time taken to carry out procedures with and without the use of bioreplicas (in minutes), discrepancies between the grafts performed with and without bioreplicas and bone defects (mm), and postoperative complications were registered. RESULTS: No significant differences were recorded for measurements of width and length of bone defect between patient bone and the biological models. CONCLUSIONS: The use of bioreplicas obtained by rapid prototyping is effective in treatment planning.