Clinical and Histological changes after ridge preservation with two xenografts: preliminary results from a multicentre randomized controlled clinical trial.

OBJECTIVES: To evaluate and compare clinical and histological changes after ridge preservation procedures with those of spontaneous healing. MATERIALS AND METHODS: Ninety patients were enrolled in the present randomized controlled clinical trial and underwent single-tooth extraction in the premolar/molar areas. Thirty sites were grafted with collagenated cortico-cancellous (coll), 30 sites with cortical (cort) porcine bone and 30 sites underwent natural healing. Primary (vertical and horizontal bone changes after 3 months) and secondary outcomes (histomorphometric after 3 months) were evaluated at implant placement. RESULTS: The vertical bone changes at the grafted sockets were significantly (p < 0.0001) lower (0.30 mm for cort group and 0.57 mm for coll group) when compared to non-grafted sockets (2.10 mm for nat group). Moreover, the width reduction of the coll (0.93 mm) and cort (1.33 mm) groups was significantly lower (p < 0.0001) than the non-grafted group (3.60 mm). The analysis of subgroups attested that when premolar and molar sites were compared, the buccal bone loss appeared to be dependent both on tooth position and grafting material employed. CONCLUSION: The ridge preservation procedures had significantly better outcomes when compared to natural healing. The biomaterials did not differ for maintenance of bone width; even though, the bone height seemed to be better preserved with the cortical porcine bone.

Volumetric analysis of remodelling pattern after ridge preservation comparing use of two types of xenografts. A multicentre randomized clinical trial.

OBJECTIVES: The aim of this randomized clinical trial was to analyse and compare the volumetric changes after ridge preservation procedures using two different biomaterials and to evaluate associations between outcome variables and pristine three-dimensional aspects of the ridges. MATERIALS AND METHODS: Twenty-eight patients subjected to single-tooth alveolar ridge preservation were enrolled in the present multicentre, single-blind, prospective and randomized clinical trial. Fourteen sites were randomly allocated to each experimental group. The experimental sites were grafted with pre-hydrated collagenated cortico-cancellous porcine bone (coll group) or with a cortical porcine bone (cort group) and a collagen membrane; a secondary soft tissue healing was obtained for all experimental sites. Plaster casts were scanned (preoperative, at 1 and 3 months postoperative). Analysis of volumes and areas was performed, and all measured variables were statistically compared. RESULTS: Intragroup analyses at 3 months revealed that when examining changes related to three-dimensional features of remodelling patterns (volume, surfaces, height and shape), the two biomaterials showed similar behaviours with a minor loss in volume and ridge surface. Intergroup analysis at 3-month survey revealed that volume resorption of the coll group (244 mm3 ) was significantly lower (P = 0.0140) than that of the cort group (349 mm3 ). The reduction for basal surface appeared significantly different between the two groups at 1-month survey only (P = 0.0137), while the final basal surface reduction was 4.9 and 12.2 mm2 for coll and cort group, respectively. The superior surface reduction was 40.8 mm2 for coll and 50.7 mm2 for cort group, with no significant difference between the two groups. CONCLUSION: At the 3rd month analysis, coll group showed a significantly lower reduction of ridge volume and a significantly smaller shrinkage of the basal area when compared to the cort group; moreover, the coll group experienced a smaller superior surface shrinkage when compared to the cort group, even though no significance was evaluated.

Biological width formation to immediate implants placed at different level in relation to the crestal bone: an experimental study in dogs.

PURPOSE/AIM: Evaluate differences in bone remodeling, soft tissue reactions and biological width formation around immediate implants placed at different level in relation to the crestal bone in beagle dogs. MATERIAL AND METHODS: The mandibular second, third and fourth premolars of six beagle dogs were extracted, and three implants were placed in the right side of each dog. Healing abutments were adjusted (n = 18). After 4 weeks, the procedure was repeated on the left side of the mandible (n = 18). Randomly, three implants were placed at crestal level (control group), and three implants were placed 2 mm subcrestally (test group) in relation to the crestal bone in each animal. The dogs were sacrificed after 8 weeks from the first surgical procedure, and biopsies were obtained. Samples were processed for ground sectioning. Histometric analysis was carried out to compare buccal and lingual bone resorption, soft tissue behavior and biological width formation in both groups. RESULTS: Crestal bone resorption was higher in the test group when considering the difference of 2 mms (IS-B = 2.05 ± 0.36 mm, control; 1.75 (+2) ± 0.38 mm, test). However, the dimensions of the biological width were similar for both groups (PM-C = 3.34 ± 0.53 mm, control; 3.13 ± 0.55 mm, test). CONCLUSIONS: The alterations that occurred in the peri-implant soft tissues may be related to the hard tissue remodeling, showing similar quantitative findings in the biological width formation in both groups. Even though the subcrestal placement might reduce the distance from the implant shoulder to the first bone-to-implant contact and reestablish the biological width dimension in a most coronal position, it might not have any effect on minimizing the marginal bone loss.

Crestal bone reactions to immediate implants placed at different levels in relation to crestal bone. A pilot study in Foxhound dogs.

OBJECTIVES: The aim of the present study was to evaluate bone-to-implant contact (BIC) and bone remodeling dynamics after immediate implant placement at different levels in relation to the crestal bone. MATERIALS AND METHODS: The mandibular second, third, and fourth premolars of six Foxhound dogs were extracted bilaterally. Randomly, three implants were immediately placed in the hemi-arches of each dog, crestally or 2 mm subcrestally. Three dogs were allowed an 8-week submerged healing period, and the other three at 12-week submerged healing period. The animals were sacrificed at 12 weeks and samples were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out to compare BIC, bone neoformation, and bone remodeling. RESULTS: All implants osseointegrated clinically and histologically. Healing patterns examined microscopically at eight and twelve weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. The Total BIC mean value for the crestal group 44.52% at 8 weeks and 39.50% at 12 weeks, and for the subcrestal group was 47.33% at 8 weeks and 53.85% at 12 weeks%. There was less bone resorption in the subcrestal group (test) than in crestal group (control). CONCLUSIONS: Within the limitations of this study, our 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 crest may be expected when implants are placed 2 mm subcrestally. Moreover, higher BIC values were found in implants placed subcrestally.

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%.

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.

Tissue response following papilla-sparing and sulcular incisions in oral surgery--an experimental study.

OBJECTIVES: The objective of this study is to compare tissue reduction following papilla-sparing and sulcular incisions in oral surgical indications. MATERIAL AND METHODS: Five beagle dogs were used. Three months after tooth extraction of P2-M1, notches were prepared at the height of the interproximal gingiva into M2 and P1. Papilla-sparing and sulcular incisions were randomly performed, full-thickness flaps elevated and flaps repositioned. Three months postoperatively, tissue reduction was assessed using a digital calliper, mean values were calculated per group and analysed using a Wilcoxon matched-pair rank test. RESULTS: Papilla-sparing incisions revealed significantly less (p < 0.05) tissue reduction than sulcular incision techniques. CONCLUSION: Papilla-sparing incisions seem to induce less tissue response following flap surgery compared to sulcular incisions in oral surgical indications. Nevertheless, tissue reduction was seen in both groups. CLINICAL RELEVANCE: For surgical approaches without the necessity of direct access to the root surface (i.e., implantology, oral surgery), papilla-sparing incisions may be superior compared to sulcular incisions.

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.

Ultrastructural study by backscattered electron imaging and elemental microanalysis of biomaterial-to-bone interface and mineral degradation of bovine xenografts in maxillary sinus floor elevation.

OBJECTIVES: The aim of this study was to perform an ultrastructural study of the bone-to-biomaterial interface and biomaterial mineral degradation in retrieved bone biopsies following maxillary sinus augmentation using bovine xenografts (Endobon(®)) in 15 clinical cases. MATERIALS AND METHODS: Nine months after sinus lifting, bone cores were harvested from the maxillary sinus. The specimens were processed for observation under a scanning electron microscope with backscattered electron imaging (SEM-BSE). In addition, chemical analysis and elemental mapping of the mineral composition were generated using a microanalytical system based on energy-dispersive X-ray spectrometry (EDX). RESULTS: No clinical complications occurred during surgery. Scanning electron microscopy revealed that newly formed bone was closely attached to the xenograft. Elemental analysis showed a significantly high Ca/P ratio in the residual biomaterials (3.031 ± 0.104) compared with the interface (2.908 ± 0.115) and new bone (2.889 ± 0.113), which suggests that there may be a gradual diffusion of Ca ions from the biomaterial into the newly forming bone at the interface as part of the biomaterial's resorption process. EDX analysis of the residual bovine biomaterial showed particle categories with different mean Ca/P ratios according to size, pointing to different stages of the resorption process. CONCLUSIONS: The biomaterial proved to be biocompatible and osteoconductive when used as a bone substitute for maxillary sinus elevation. The grafting material used is not a completely resorbable material over the time period covered by this study.

Ultrastructural study by backscattered electron imaging and elemental microanalysis of bone-to-biomaterial interface and mineral degradation of porcine xenografts used in maxillary sinus floor elevation.

OBJECTIVES: The aim of this study was to carry out an ultrastructural study of the biomaterial-to-bone interface and biomaterial mineral degradation in retrieved bone biopsies following maxillary sinus augmentation using collagenized porcine xenografts (Osteobiol(®) Mp3) in 15 clinical cases. MATERIALS AND METHODS: Nine months after sinus lifting, bone cores were harvested from the maxillary sinus. The specimens were processed for observation under a scanning electron microscope with backscattered electron imaging (SEM-BSE). In addition, chemical analysis and elemental mapping of the mineral composition were generated using a microanalytical system based on energy-dispersive X-ray spectrometry (EDX). RESULTS: No clinical complications were evident during surgery. Scanning electron microscopy revealed that newly formed bone had become closely attached to the xenograft. Statistical analysis showed a significantly high Ca/P ratio in the biomaterial (2.46 ± 0.16) and at the bone interface (2.00 ± 0.48) compared to bone (1.97 ± 0.36), which suggests that there may be a gradual diffusion of Ca ions from the biomaterial into the newly forming bone at the interface as part of the biomaterial's resorption process. EDX analysis of the residual porcine biomaterial at different points showed some particle categories with different mean ratios of Ca/P according to size, pointing to different stages of the resorption process. CONCLUSIONS: The biomaterial proved to be biocompatible, bioreabsorbable and osteoconductive when used as a bone substitute for maxillary sinus elevation. SEM-BSE revealed that newly formed bone had become closely attached to the xenografts. EDX analysis monitored the resorption process of the porcine bone xenograft. Elemental mapping showed that there was a gradual diffusion of Ca ions from the biomaterial to the newly forming bone at the interface.

Melatonin promotes angiogenesis during repair of bone defects: a radiological and histomorphometric study in rabbit tibiae.

OBJECTIVES: The pineal gland hormone, melatonin, is an immunomodulator and neuroendocrine hormone; it also stimulates monocyte, cytokine and fibroblast proliferations, which influence angiogenesis. The aim of this study was to investigate the effects of melatonin on angiogenesis during bone defect repair by means of radiological and histomorphometric evaluations of bone response to melatonin implants. MATERIALS AND METHODS: Twenty New Zealand rabbits weighing 3,900-4,500 g were used. Twenty melatonin implants were inserted in the proximal metaphyseal area of the animals' right tibia and 20 control areas were located in the left proximal metaphyseal area. Following implantation, the animals were sacrificed in groups of five, after 1, 2, 3 and 4 weeks, respectively. Anteroposterior and lateral radiographs were taken, and radiographic thermal imaging analysis was performed for all groups at different time stages following implant insertion. Samples were sectioned at 5 µm and stained using Hematoxylin-Eosin and Masson's trichrome, supplementing radiographic findings with histomorphometric analysis. RESULTS: After 4 weeks, radiological images showed complete repair of the bone defects. No healed or residual bone alterations attributable to the presence of the melatonin implant were observed. Histomorphometric analysis at 4 weeks showed the presence of a higher density newly formed bone. There were statistically significant differences in the length of cortical formation between the melatonin group and the control group during the first weeks of the study; there were also statistically significant differences in the number of vessels observed in the melatonin groups at the first two study stages. CONCLUSION AND CLINICAL RELEVANCE: Melatonin may have potential beneficial effects on bone defect repair.

Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part I: a pilot study in dogs.

PURPOSE: The aim of the present study was to evaluate bone remodeling and bone-to-implant contact (BIC) after immediate placement at different levels in relation to the crestal bone of Beagle dogs. MATERIALS AND METHODS: The mandibular bilateral second, third and fourth premolars of six Beagle dogs were extracted and six implants were immediately placed in the hemi-arches of each dog. Randomly, three cylindrical and three tapered implants were inserted crestally (control group) and 2 mm subcrestally (experimental group). Both groups were treated with a minimal mucoperiosteal flap elevation approach. A gap from the buccal cortical wall to the implant was always left. Three dogs were allowed a 4-week submerged healing period and the other three an 8-week submerged healing period. The animals were sacrificed and biopsies were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out in order to compare buccal and lingual bone height loss, and BIC between the two groups. RESULTS: All implants osseointegrated clinically and histologically. Healing patterns examined microscopically at 4 and 8 weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. The distance from the top of the implant collar to the first BIC in the lingual crest (A-Lc) showed a significant difference (P=0.0313): 1.91 ± 0.2 mm in the control group and 1.08 ± 0.2 mm in the experimental group. There was less bone resorption in subcrestal implants than crestal implants. The mean percentage of newly formed BIC was greater with the cylindrical implant design (46.06 ± 4.09%) than with the tapered design (32.64 ± 3.72%). CONCLUSION: These 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 Lc may be expected when implants are placed 2 mm subcrestally.

Peri-implant bone reactions to immediate implants placed at different levels in relation to crestal bone. Part II: a pilot study in dogs.

PURPOSE: The aim of the present study was to evaluate bone-to-implant contact (BIC) and bone remodeling dynamics after immediate implant placement at different levels in relation to the crestal bone with two different implant designs in beagle dogs. MATERIALS AND METHODS: The mandibular second, third and fourth premolars of six beagle dogs were extracted bilaterally and three implants were immediately placed in the hemi-arches of each dog. Randomly, three cylindrical and three tapered implants were inserted crestally (control group) or 2 mm subcrestally (test group). Both groups were treated with a minimal mucoperiosteal flap elevation approach. A gap from the buccal cortical wall to the implant was always left. Three dogs were allowed a 4-week submerged healing period and the other three an 8-week submerged healing period. The animals were sacrificed and samples were obtained. Biopsies were processed for ground sectioning. Histomorphometric analysis was carried out in order to compare BIC, de novo bone formation and bone remodeling. RESULTS: All implants osseointegrated clinically and histologically. Healing patterns examined microscopically at 4 and 8 weeks for both groups (crestal and subcrestal) yielded similar qualitative bone findings. The total BIC mean value for the crestal group was 36.48 ± 3.4% and for the subcrestal group was 41.46 ± 4.2%. The mean percentage of newly formed BIC was greater with the cylindrical implant design (46.06 ± 1.09%) than with the tapered design (33.89 ± 1.72%). There was less bone resorption in the subcrestal group (test) than crestal group (control). CONCLUSION: These 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 crest may be expected when implants are placed 2 mm subcrestally. Moreover, higher BIC values were found in cylindrical implants placed subcrestally.

Crestal bone loss evaluation in osseotite expanded platform implants: a 5-year study.

OBJECTIVE: The aim of this prospective clinical study was to evaluate the survival rates at 5 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, 3, 6, 9, 12, 24, 36 months and 5 years. Primary stability was measured with resonance frequency analysis (RFA) using the Osstell Mentor device. Sixty-four implants were placed in 32 men and 32 women ranging in age between 29 and 60 (mean: 39.64 ± 5.16 years). RESULTS: Mean mesial bone loss was 0.08 mm (SD 0.42). Mean distal bone loss was 0.14 mm (SD 0.56). Over the course of the 5 years, the mean RFA value was 72.5 ± 3.1 SD. CONCLUSION: The platform-switched implants remained stable over the course of 5 years and had an overall survival rate of 97.1%.

Socket seal surgery: Clinical uses in implant dentistry and guided bone regeneration procedures for single tooth replacement in the esthetic zone.

Restoring failing anterior teeth with a dental implant is considered a complex treatment even with thorough biologic knowledge of the situation. The goal is to produce a result in which the labial soft tissues and the papillae remain stable over time. Treatment of the fresh extraction socket in the alveolar ridge presents a challenge in everyday clinical practice. Regardless of the subsequent treatment, maintenance of the ridge contour will frequently facilitate all further therapeutic steps. Socket seal surgery and socket preservation in combination with immediate, early, or delayed implant placement can be valuable procedures for single tooth replacement. However, their potential as ridge preservation techniques in these different situations still needs to be demonstrated. The use of these procedures is illustrated in three consecutive cases.

Connective Tissue Characteristics around Healing Abutments of Different Geometries: New Methodological Technique under Circularly Polarized Light.

PURPOSE: To describe contact, thickness, density, and orientation of connective tissue fibers around healing abutments of different geometries by means of a new method using coordinates. MATERIALS AND METHODS: Following the bilateral extraction of mandibular premolars (P2, P3, and P4) from six fox hound dogs and a 2-month healing period, 36 titanium implants were inserted, onto which two groups of healing abutments of different geometry were screwed: Group A (concave abutments) and Group B (wider healing abutment). After 3 months the animals were sacrificed and samples extracted containing each implant and surrounding soft and hard tissues. Histological analysis was performed without decalcifying the samples by means of circularly polarized light under optical microscope and a system of vertical and horizontal coordinates across all the connective tissue in an area delimited by the implant/abutment, epithelium, and bone tissue. RESULTS: In no case had the connective tissue formed a connection to the healing abutment/implant in the internal zone; a space of 35 ± 10 µm separated the connective tissue fibers from the healing abutment surface. The total thickness of connective tissue in the horizontal direction was significantly greater in the medial zone in Group B than in Group A (p < .05). The orientation of the fibers varied according to the coordinate area so that internal coordinates showed a higher percentage of parallel fibers in Group A (p < .05) and a higher percentage of oblique fibers in Group B (p < .05); medial coordinates showed more oblique fibers (p < .05); and the area of external coordinates showed the highest percentage of perpendicular fibers (p < .05). The fiber density was higher in the basal and medial areas (p < .05). CONCLUSIONS: Abutment geometry influences the orientation of collagen fibers; therefore, an abutment with a profile wider than the implant platform favors oblique and perpendicular orientation of collagen fibers and greater connective tissue thickness.

Histological and Histomorphometric Evaluation of Zirconia Dental Implants Modified by Femtosecond Laser versus Titanium Implants: An Experimental Study in Fox Hound Dogs.

PURPOSE: This study applied femtosecond laser technology to zirconia dental implants (Bredent GmbH & Co.KG, Senden, Germany) to generate a surface texture of microgrooves over the entire intraosseous surface, analyzing its behavior in an in vivo model in comparison with titanium implants with sandblasted and acid-etched surfaces. MATERIALS AND METHODS: The study used six American Fox Hound dogs. Each received four implants per hemi-mandible, making a total of eight implants per animal. The 48 immediate loaded implants were divided into two groups of 24 titanium implants (control group) and 24 zirconia implants (study/test group), distributed randomly. Bone-to-implant contact (BIC) values and crestal resorption were determined at 1 and 3 months, also measuring calcium, phosphorous, and carbon concentrations by means of energy dispersive x-ray. RESULTS: BIC percentages after 30 days were 51.36% for titanium implants and 44.68% for zirconia implants. After 90 days, values increased to 61.73% in titanium and 47.94% in zirconia implants. After 30 days, there was more crestal bone lost in the titanium group (0.77 mm) compared with the zirconia group (0.01 mm). After 90 days, zirconia implants showed greater marginal bone resorption (1.25 mm) compared with the titanium group (0.37 mm). CONCLUSIONS: The present study shows that zirconia implants with modified surfaces can produce good osseointegration values when compared with titanium implants in terms of BIC and crestal bone resorption at 1 and 3 months.

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.