Deproteinized bovine bone mineral particles and osseointegration of implants without primary bone contact: an experimental study in dogs (original) (raw)
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Healing of implants installed in over- or under-prepared sites - An experimental study in dogs
Clinical Oral Implants Research, 2014
Objective: To study bone healing at implants installed with different insertion torques. Material and methods: In six Labrador dogs, all mandibular premolars and first molars were extracted. After 4 months of healing, flaps were elevated, and two implant sites were prepared at each side of the mandible. In the right side of the mandible, the distal sites were prepared conventionally, while the mesial sites were over-prepared by 0.2 mm. As a consequence, a final insertion torque of~30 Ncm at the distal and a minimal insertion torque close to 0 Ncm at the mesial sites were obtained. In the left sides of the mandible, however, the recipient sites were underprepared by 0.3 mm resulting in an insertion torque of ≥70 Ncm at both implants. Cover screws were applied, and flaps sutured to fully submerge the experimental sites. After 4 months, the animals were sacrificed and ground sections obtained for histological evaluation. Results: The mineralized bone-to-implant contact was in the range of 55.2-62.1%, displaying the highest value at implants with~30 Ncm insertion torque and the lowest value at the implant sites with close to 0 Ncm insertion torque. No statistically significant differences were revealed. Bone density was in the range of 43.4-54.9%, yielding the highest value at implants with ≥70 Ncm insertion torque and the lowest at the implant sites with close to 0 Ncm insertion torque. The difference between the sites of~30 Ncm and the corresponding ≥70 Ncm insertion torque reached statistical significance. Conclusions: Similar amounts of osseointegration were obtained irrespective of the insertion torque applied. Moreover, implants installed in sites with close to 0 Ncm insertion torque may properly osseointegrate as well.
Clinical Implant Dentistry and Related Research, 2001
Background: Previous experimental studies have shown a higher degree of bone-implant contact for surface-enlarged implants compared with machined implants. Yet, there is insufficient evidence that such implants show higher stability and an increased survival rate. Purpose: The purpose of this investigation was to study the integration and stability of grit-blasted implants with retention elements on the implant neck, with and without marginal bone defects, compared with machined implants without retention elements. Materials and Methods: After tooth extraction of the mandibular premolars in six dogs, two grit-blasted, partly microthreaded Astra Tech implants and one standard BrHnemark implant were bilaterally placed in each dog. On one side, 3 x 3 mm large buccal defects were created, to expose three to four implant threads. The contralateral side served as control, and no defects were made. The animals were sacrificed after 4 months of healing. Implant stability was measured using resonance frequency analysis at implant installation and after 4 months of healing. Histologic and histornorphometric evaluation was made after 4 months of healing. Results: Resonance frequency analysis indicated that all implants in the test and control groups were osseointegrated after 4 months, with a tendency toward higher implant stability for the Astra Tech implants. There was a statistically significant higher increase in resonance frequency for the Astra test implants compared with their corresponding controls. Histology and histomorphometry showed well-integrated implants with varying degrees of bone repair at the defect sites. The greater bone-implant contact for the Astra implants was statistically significant. No significant difference between the implants in amount of bone filling the threads was recorded. Conclusions: The Astra Tech implants tested showed a higher degree of bone-implant contact and higher level of bone regenerated at defect sites compared with the BrHnemark implants. Resonance frequency analysis demonstrated a significantly higher increase in the Astra test implants compared with their control groups than did the BrHnemark test implants versus their controls.
Clinical Oral Implants Research, 2008
Aims: This study was designed to evaluate the effect of gap width and graft placement on bone healing around implants placed into simulated extraction sockets in the mandibles of four beagle dogs. Materials and methods: Four Ti-Unite s implants (13 mm  3.3 mm) were placed on each side of the mandible. Three implants were surrounded by a 1.35 mm circumferential and a 5 mm deep gap around the coronal portion of the implants. A fourth implant was inserted conventionally into both sides of the mandibles as a positive control. The gaps were filled with either Bio-Oss s
Clinical Oral Implants Research, 2011
The aim of this study was to evaluate the osseointegration of implants placed in areas with artificially created bone defects, using three bone regeneration techniques. Material and methods: The experimental model was the rabbit femur (16), where bone defects were created and implants were placed. The peri-implant bone defects were filled with a deproteinized bovine bone mineral, NuOsst (N), NuOsst combined with plasma rich in growth factors (PRGF) (N þ PRGF), NuOsst covered by an RCM 6 membrane (N þ M), or remained unfilled (control group [C]). After 4 and 8 weeks, the animals were euthanized and bone tissue blocks with the implants and the surrounding bone tissue were removed and processed according to a histological protocol for hard tissues on non-decalcified ground sections. The samples were studied by light and electron scanning microscopy, histometric analysis was performed to assess the percentage of bone in direct contact with the implant surface and a statistical analysis of the results was performed. Results: In the samples analyzed 4 weeks after implantation, the percentage of bone tissue in direct contact with the implant surface for the four groups were 57.66 AE 24.39% (N), 58.62 AE 20.37% (N þ PRGF), 70.82 AE 20.34 % (N þ M) and 33.07 AE 5.49% (C). In the samples with 8 weeks of implantation time, the percentage of bone in direct contact was 63.35 AE 27.69% (N), 58.42 AE 24.77% (N þ PRGF), 78.02 AE 15.13% (N þ M) and 40.28 AE 27.32% (C). In terms of the percentage of bone contact, groups N and N þ M presented statistically significant differences from group C in the 4-week trial test (Po0.05; ANOVA). For the 8-week results, only group N þ M showed statistically significant differences when compared with group C (Po0.05; ANOVA). Conclusion: In conclusion, the NuOsst granules/RCM 6 membrane combination presented a percentage of bone contact with the implant surface statistically greater than in the other groups.
Appositional bone formation in marginal defects at implants. An experimental study in the dog
Clinical Oral Implants Research, 2003
In a previous experiment, it was demonstrated that a wide marginal defect around an implant can heal with a high degree of osseointegration. The present experiment was performed to evaluate the degree and quality of de novo bone formation and osseointegration in marginal defects adjacent to submerged titanium implants. All mandibular premolars and 1st molars were extracted in four Labrador dogs. Four experimental sites were identified in the right side of the mandible. In two sites, custommade implants with a sandblasted, large grit, acid-etched (SLA) surface were installed without further ostectomy (control sites). In the two remaining sites (test sites), a specially designed step drill was used to widen the marginal 5 mm of the canal. A barrier membrane was used to cover the implants in the defect sites. All implants were submerged. One month later, an identical procedure, including site preparation and implant installation, was performed in the left side of the mandible. Two months following the first implant installation procedure, biopsies were collected and prepared for sectioning. Ostectomy and implant installation in the control location resulted in a series of bone tissue alterations which eventually allowed newly formed bone to establish contact with the SLA surface. The marginal defect lateral to the implant in the test locations gradually became filled with newly formed bone. De novo bone formation started within the walls of the surgically prepared defect. Bone-to-implant contact was first established in the apical portion of the gap. This new bone tissue was in the coronal direction continuous with a dense, non-mineralized 'implant attached' soft tissue which, over time, also became mineralized to increase the height of the zone of bone-toimplant contact. The results suggest that healing of a wide marginal defect around an implant is characterized by appositional bone growth from the lateral and apical bone walls of the defect.
Histologic and Immunohistochemical Description of Early Healing at Marginal Defects Around Implants
International Journal of Periodontics & Restorative Dentistry, 2014
This study reports on the histologic characteristics of the early phases of implant osseointegration, focusing on osteopontin concentrations in the coronal area of implants placed with marginal defects and in control sites without defect preparation. In the mandibular right area of 12 dogs, two recipient sites were prepared and the margins were widened to obtain a gap of 0.5 mm at one site (small defect) and 1.25 mm at another site (large defect). Implants were placed and allowed a fully submerged healing. The procedure was subsequently performed in the left side in such a way as to obtain healing times of 5, 10, 20, and 30 days. Paraffin sections were stained with osteopontin antibodies and analyzed. At control implants, scarcely organized collagen fibers were observed in the space between the pristine bone and implant and were quickly replaced by mineralized tissue. In the small and large defects, the collagen fibers were organized in a layer that ran parallel to the implant at day 10 and became denser and thicker with time. Osteopontin was evenly distributed in the peri-implant tissue at control implants, while it was mainly located in the collagen bundle section around the implants placed in the defects.