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.

Bone neo-formation and mineral degradation of 4Bone.(®) Part II: histological and histomorphometric analysis in critical size defects in rabbits.

OBJECTIVE: To carry out the histological and histomorphometric plus radiological analysis of biphasic ceramic. MATERIALS AND METHOD: In this study, porous HA/ßTCP (4Bone(®) ) ceramic material was tested for the bone repairing capacity and osteoinductive potential in a New Zealand rabbit model. The ratio of the ceramic's components HA/ßTCP was 60/40 (in wt%). RESULTS: The 4Bone(®) showed significantly more bone formation in the pores and in the periphery of the graft than the control group. Histomorphometric analysis revealed that the ceramic material (66.43% ± 0.29) produced higher values of bone-to-implant contact (BIC) percentages (higher quality, closer contact); moreover, defect closure was significative higher in relation with control group (64.15% ± 3.52). CONCLUSIONS: 4Bone(®) is a biocompatible, partially resorbable and osteoconductive grafting material. Biphasic graft material of HA/ßTCP with a porosity of 95% without loading favors new bone formation.

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.

Novel hybrid drilling protocol: evaluation for the implant healing--thermal changes, crestal bone loss, and bone-to-implant contact.

OBJECTIVES: To evaluate a new hybrid drilling protocol, by the analysis of thermal changes in vitro, and their effects in the crestal bone loss and bone-to-implant contact in vivo. MATERIALS AND METHODS: Temperature changes during simulated osteotomies with a hybrid drilling technique (biologic plus simplified) (test) versus an incremental drilling technique (control) were investigated. One hundred and twenty random osteotomies were performed (60 by group) in pig ribs up to 3.75-mm-diameter drill to a depth of 10 mm. Thermal changes and time were recorded by paired thermocouples. In a parallel experiment, bilateral mandibular premolars P2, P3, P4, and first molar M1 were extracted from six dogs. After 2-month healing, implant sites were randomly prepared using either of the drilling techniques. Forty eight implants of 3.75 mm diameter and 10 mm length were inserted. The dogs were euthanized at 30 and 90 days, and crestal bone loss (CBL) and bone-to-implant contact (BIC) were evaluated. RESULTS: The control group showed maximum temperatures of 35.3 °C ± 1.8 °C, ΔT of 10.4 °C, and a mean time of 100 s/procedure; meanwhile, the test group showed maximum temperatures of 36.7 °C ± 1.2 °C, ΔT of 8.1 °C, and a mean time of 240 s/procedure. After 30 days, CBL values for both groups (test: 1.168 ± 0.194 mm; control: 1.181 ± 0.113 mm) and BIC values (test: 43 ± 2.8%; control: 45 ± 1.3%) were similar, without significant differences (P > 0.05). After 90 days, CBL (test: 1.173 ± 0.187 mm; control: 1.205 ± 0.122 mm) and BIC (test: 64 ± 3.3%; control: 64 ± 2.4%) values were similar, without significant differences (P > 0.05). The BIC values were increased at 90 days in both groups compared with the 30-day period (P < 0.05). CONCLUSIONS: Within the limitations of this study, the new hybrid protocol for the preparation of the implant bed without irrigation, increase the temperature similarly to the incremental conventional protocol, and requires twice the time for the completion of the drilling procedure in vitro. Crestal bone loss and bone-to-implant contact in the hybrid drilling protocol are comparable with the conventional drilling protocol and do not affect the osseointegration process in vivo.

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.

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.

Narrow- versus mini-implants at crestal and subcrestal bone levels. Experimental study in beagle dogs at three months.

OBJECTIVE: The objective of this study was to evaluate the osseointegration and crestal bone loss (CBL) in two implant designs with different diameters (Mini Sky® and Narrow Sky®) implants, placed at different vertical levels at healed canine ridges. MATERIAL AND METHODS: The second, third, and fourth mandibular premolars of six Beagle dogs were extracted bilaterally. After 2 months healing, four implants divided into two groups according to their diameters (i.e., Narrow Sky® and Mini Sky®) were placed in each hemi-mandible at the level of the bone crest or 2 mm subcrestally. The animals were euthanized at 12 weeks and undecalcified samples were processed for histology. Histomorphometric analysis was carried out to compare bone-to-implant contacts (BIC) and crestal bone loss (CBL). RESULTS: There were not significant differences in CBL between groups when the implants were placed at subcrestal bone level (p > 0.05), meanwhile the CBL was significantly higher for both groups when the implants were inserted at crestal level (p < 0.05). All implants were osseointegrated presenting a minimum BIC percentage of 56%. The major percentages of BIC were found for both groups at subcrestal level (p < 0.05). CONCLUSIONS: Within the limitations of this experimental study may be concluded that the implant diameter does not affect the CBL. BIC values are affected by implant diameter and design been higher for narrow implants compared to mini-implants. Subcrestal insertion of both implants favors crestal bone preservation but crestal insertion of both designs is associated with crestal bone loss CLINICAL RELEVANCE: The study shows that narrow implants protect peri-implant crestal bone.

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.

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.

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.

Effects of growth hormone on initial bone formation around dental implants: a dog study.

OBJECTIVE: The aim of this study was to evaluate the effects of topical application of growth hormone (GH) on the osteointegration of dental implants in dogs at 5 and 8 weeks after surgery. MATERIALS AND METHODS: Mandibular premolars and molars were extracted from 12 Beagle dogs. Four screw implants were placed in each mandible. Before implant placement, 4 IU of GH were applied to the test sites (TS); no treatment was applied to control sites (CS). Morphometric parameters, bone-to-implant contact (BIC), peri-implant connective tissue, interthread bone and newly formed bone were measured. The Student's t-test for was used for statistical analysis of data obtained. RESULTS: After 5 weeks of treatment, BIC values varied slightly between 34.33 ± 2.35% (CS) and 35.76 ± 2.96% (TS). Interthread bone tissue was 64.08 ± 8.68 at CS and 72.86 ± 2.93 at TS, with statistical significance (P<0.05). Bone neoformation was 72.53 ± 4.54 at the CS and 80.74 ± 1.65 for the GH group, these being statistically significant differences (P<0.05). After 8 weeks, BIC had slightly increased for the GH group (36.47 ± 3.09 vs. 39.61 ± 2.34). Interthread bone was 80.57 ± 2.28 at the CS and 82.58 ± 2.44 at the GH site, which was statistically significant. Bone neoformation was 88.09 ± 1.38 at CS and 91.01 ± 1.52 at TS, showing statistical significance (P<0.05). CONCLUSION: Topical application of 4 IU of GH like a biomimetic agent at the moment of implant placement has no significant effects on the BIC at 5 and 8 weeks, although bone neoformation and inter-thread bone values did increase significantly.

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.

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.

Immediate maxillary restoration of single-tooth implants using platform switching for crestal bone preservation: a 12-month study.

PURPOSE: The aim of this prospective clinical study was to evaluate the survival rates at 12 months of a new implant design placed in the anterior and premolar areas of the maxilla and immediately restored with single crowns. Crestal bone loss was also assessed. MATERIALS AND METHODS: Patients seeking replacement of at least one failing maxillary tooth were recruited to participate in the study. Exclusion criteria included compromised general health conditions, severe maxillomandibular skeletal discrepancies, severe parafunctional habits, drug or alcohol abuse, poor oral hygiene, and a need for bone augmentation. Implants incorporating the platform-switching concept were placed into fresh extraction sockets in the maxilla, with each patient receiving a provisional restoration immediately after implant placement. After 15 days, definitive restorations were inserted. Mesial and distal bone levels were evaluated with digital radiography on the day after implant placement, 15 days later, and 1, 2, 3, 6, 8, and 12 months later. Primary stability was measured with resonance frequency analysis (RFA). Analysis of variance for repeated measures and a binary logistic regression model were used to assess the data. RESULTS: Sixty-one implants were placed into fresh extraction sites in 25 men and 25 women ranging in age from 29 to 51 years (mean, 39.64 +/- 6.06 years). One of the implants failed, and one was lost to follow-up. The mean bone loss measured on the mesial was 0.08 mm (SD 0.53 mm). Mean distal bone loss was 0.09 mm (SD 0.65 mm). Over the course of 12 months, the mean RFA value between baseline and 12 months was 71.1 +/- 6.2. CONCLUSIONS: The implants remained stable over the course of 12 months and had an overall survival rate of 96.7%. Minimal crestal bone loss was recorded around the surviving implants.

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.

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.

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)