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- Ivanoff, Carl-Johan, et al.
(författare)
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Influence of implant diameters on the integration of screw implants. An experimental study in rabbits.
- 1997
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Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 0901-5027. ; 26:2, s. 141-8
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Tidskriftsartikel (refereegranskat)abstract
- The influence of diameter on the integration of titanium screw-shaped implants was studied in the rabbit tibia by means of removal torque measurements and histomorphometry. Implants 3.0, 3.75, 5.0, and 6.0 mm in diameter and 6.0 mm long were inserted through one cortical layer in the tibial metaphyses of nine rabbits and allowed to heal for 12 weeks. The implants were then unscrewed with a torque gauge, and the peak torque required to shear off the implants was recorded. The histologic analysis in undemineralized ground sections comprised (1) a gross description of the implant sites and assessments of (2) the total implant length in bone and (3) in the cortical passage, as well as (4) the thickness of the cortical bone adjacent to the implants. From the removal torque values obtained and morphometric measurements, a mean shear stress value was calculated for each implant type. The biomechanical tests showed a statistically significant increase of removal torque with increasing implant diameter. The resistance to shear seemed to be determined by the implant surface in supportive cortical bone, whereas the newly formed bone at the periosteal and endosteal surfaces did not seem to have any supportive properties after 12 weeks. It is suggested that wide diameter implants may be used clinically to increase implant stability.
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- Ivanoff, Carl-Johan, et al.
(författare)
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Influence of mono- and bicortical anchorage on the integration of titanium implants. A study in the rabbit tibia.
- 1996
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Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 0901-5027. ; 25:3, s. 229-35
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Tidskriftsartikel (refereegranskat)abstract
- The study aimed to evaluate the removal torque and bone tissue response to titanium implants supported by one or two cortical layers. A total of 72 screw titanium implants, either 10 or 16 mm in length and 3.75 mm in diameter, were inserted in right and left tibiae of 18 adult New Zealand rabbits. The implants engaged either one or two cortical layers, and the animals were allowed a healing period of 6 or 12 weeks. The degree of integration was assessed by measuring the removal torque with a torque gauge manometer. Histomorphometric calculations were also performed in 10-microns-thick ground sections. All implants were clinically stable at the end of the experiment. The removal torque was two times higher for the bicortical implants after 6 weeks, and three times higher after 12 weeks, than for the monocortical ones. The 16-mm implants also showed a statistically higher amount of bone contact and bone area after 6 and 12 weeks, respectively, than the short ones. The results support bicortical anchorage of implants also in the clinical situation.
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| 6. |
- Ivanoff, Carl-Johan, et al.
(författare)
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Reintegration of mobilized titanium implants. An experimental study in rabbit tibia.
- 1997
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Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 0901-5027. ; 26:4, s. 310-5
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Tidskriftsartikel (refereegranskat)abstract
- The possibility of re-establishing a rigid bone-implant fixation, i.e. osseointegration, after mechanical loosening of titanium implants, was evaluated in the rabbit tibia. Implants were inserted to engage either one (10 mm long, n = 24) or two (16 mm long, n = 24) cortical layers and were allowed to heal for six weeks. A re-entry was then made and 12 test implants in each group subjected to a reverse torque procedure until the integration failed. The remaining nonrotated 24 implants were left as controls. Thereafter all implants were allowed to heal for an additional period of six weeks. At the end of the 12 weeks, the degree of integration was assessed by measuring the removal torque for six test and six control implants in each group of implant lengths. Histomorphometric measurements were also performed on ground sections of the remaining test and control implants. A statistically significant higher removal torque was observed for the monocortical test implants than for the corresponding control implants. No differences were seen for the bicortical implants of either kind, however, no morphological differences could be revealed either, when comparing monocortical and bicortical test and control implants. These results indicate that osseointegrated implants that have been mobilized due to a traumatic disruption of the bone-implant interface, may reintegrate if allowed to heal for an additional period of time.
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- Lundgren, Anna Karin, et al.
(författare)
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An experimental rabbit model for jaw-bone healing.
- 1997
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Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 0901-5027. ; 26:6, s. 461-4
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this investigation was to study the structural and topographical bone anatomy of the right and left edentulous areas between the incisors and molars in the rabbit maxilla with regard to the symmetry of the bone, and to assess the degree of spontaneous healing of surgical defects. Anatomical and radiographic examinations together with analysis of serial histological ground sections in ten rabbits disclosed no statistically significant differences between the two sides regarding the different bone-tissue structures, i.e. they exhibit a sufficient degree of symmetry to serve as a useful bilateral test-control model. Surgical defects were made on one side of the jaw (test side) in a group of eight rabbits. This resulted in an average loss of 17% of the total bone volume after a healing period of four weeks as compared to the untreated control side. It was concluded that surgically-created defects do not show completely spontaneous healing. From a histological section of the test side, it was possible to redraw the original bone contour by interpolation between unaffected areas of bone, coronal and apical to the defect. This means that the test side of this model can also serve as its own control with regard to the amount of regenerated tissue, given that there is unaffected bone, coronal and apical to the defect.
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| 8. |
- Lundgren, Anna Karin, et al.
(författare)
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Guided jaw-bone regeneration using an experimental rabbit model.
- 1998
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Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 0901-5027. ; 27:2, s. 135-40
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to evaluate the space-maintaining capacity of two biocompatible barrier materials and to assess the effect of barrier occlusiveness on the amount of regenerated bone. Defects were prepared in the edentulous area on both sides of the maxillas in 22 rabbits. The rabbits were divided into three groups. Gore-Tex augmentation material (GTAM) (ePTFE)-barriers were placed to cover the experimental defects and compared with totally occlusive or perforated titanium foils and uncovered control defects respectively. After four weeks of healing, histological analyses and morphometrical measurements demonstrated that the amount of regenerated bone tissue was about the same underneath the collapsed GTAM-barriers as in the controls. The highest degree of regeneration was obtained in defects underneath the titanium foils, particularly if they were perforated, whether or not they were covered by GTAM-barriers. It was concluded that the space-maintaining properties of a barrier may be at least as important as barrier occlusiveness when regenerating bone defects.
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| 9. |
- Rasmusson, Lars, 1962, et al.
(författare)
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Stability assessments and histology of titanium implants placed simultaneously with autogenous onlay bone in the rabbit tibia.
- 1998
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Ingår i: International journal of oral and maxillofacial surgery. - : Elsevier BV. - 0901-5027. ; 27:3, s. 229-35
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Tidskriftsartikel (refereegranskat)abstract
- A disc-shaped bone graft was harvested from the calvarium in ten rabbits and anchored as an onlay bone graft, using a titanium implant, at the proximal tibial metaphysis. The contralateral tibia served as the control, where an implant was placed without a graft with the implant head at a height corresponding to the thickness of the graft on the test side. Resonance frequency measurements were performed 4, 8, 16 and 24 weeks postoperatively and removal torque measurements were performed at 24 weeks. A statistically significant higher implant stability, as assessed by resonance frequency measurements (RFM), was measured from 4 weeks throughout the 24-week period. The mean peak removal torque for the test implants was 50.4+/-10.0 Ncm and 30.0+/-6.9 Ncm for the control implants, which was a statistically significant difference. Histologically, the grafted bone was well incorporated and morphometry revealed more bone around the test implants. Calculations of shear stresses indicated that the grafted bone had similar biomechanical properties to the cortical bone of the recipient site. It is concluded that the integration of titanium implants in autogenous onlay bone grafts results in an increased biomechanical support of the implant. The use of RFM may also serve as a useful instrument for noninvasive monitoring of implant stability in vivo.
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| 10. |
- Chrcanovic, Bruno, et al.
(författare)
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Is the intake of selective serotonin reuptake inhibitors associated with an increased risk of dental implant failure?
- 2017
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Ingår i: International Journal of Oral and Maxillofacial Surgery. - : Elsevier BV. - 0901-5027 .- 1399-0020. ; 46:6, s. 782-788
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this retrospective study was to investigate the association between the intake of selective serotonin reuptake inhibitors (SSRIs) and the risk of dental implant failure. Patients were included if they were taking SSRIs only and no other medication, did not present any other systemic condition or compromising habits (bruxism, smoking, snuff), and complied with the use of prophylactic antibiotics for implant surgery. The multivariate generalized estimating equation (GEE) method and multilevel mixed-effects parametric survival analysis were used to test the association between SSRI exposure (predictor variable) and the risk of implant failure (outcome variable), adjusting for several potential confounders (other variables). The total number of implants with information available and meeting the necessary eligibility criteria was 931(35 failures). These were placed in 300 patients. The implant failure rate was 12.5% for SSRI users and 3.3% for nonusers (P = 0.007). Kaplan-Meier analysis showed a statistically significant difference in the cumulative survival rate (P < 0.001). The multivariate GEE model did not show a statistically significant association between SSRI intake and implant failure (P = 0.530), nor did the multilevel model (P = 0.125). It is suggested that the intake of SSRIs may not be associated with an increased risk of dental implant failure.
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