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On healing of titanium implants in biphasic calcium phosphate
Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Sinnescentrum, Department of Oral Surgery UHL.
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Previously, autogenous bone was considered the gold standard for grafting procedures in implant surgery. Today, the use of bone graft substitutes is an alternative for sinus lift procedures. Nevertheless, only a few bone substitutes are well documented and can be recommended as an alternative to autogenous bone grafts. Both deproteinized bovine bone (DBB) and tricalcium phosphate (TCP) are materials that are frequently used and well documented. During the last years a novel biphasic calcium phosphate (BCP) has been introduced to the market. Until now only a few studies have been published.

Aims: Studies I, II, III and IV. The overall aim of the present thesis was to evaluate a new biphasic calcium phosphate for bone augmentation of the maxillary sinus. Deproteinized bovine bone was used as a control.Study V. The aim of this in vitro study was to evaluate the response of human osteoblast-like cells (HOB) to nano-crystalline-diamond-particle-modified (nDP-modified) and un-modified (control) deproteinized bovine bone (DBB) and biphasic calcium phosphate (BCP) scaffolds.

Materials and Methods: Studies I, II, III and IV. The studies were based on 11 patients (six women, five men) with a mean age of 67 years (range; 50 to 79 years). All patients showed severe maxillary resorption with less than 5mm of residual alveolar bone in the floor of the maxillary sinus, which excluded conventional implant treatment. Twenty-two maxillary sinuses were augmented with BCP on one side and with DBB acting as a control at the contralateral side. Simultaneously with the augmentation procedure 22 microimplants were placed inside the augmented materials. After 8 months of graft healing the microimplants and a surrounding bone core were retrieved for histomorphometrical analysis (Paper I) and for energy dispersive spectroscopy (Paper II). After retrieval of the microimplants, 62 conventional implants were placed and left to heal for 8 weeks before rehabilitation with fixed prosthetic constructions. The conventional implants were evaluated clinically at baseline, after 1- and 3 years of loading (Papers III and IV). After 3 years of graft healing 18 biopsies were harvested from 9 patients for histomorphometrical analysis (Paper IV).

Computerized tomography (CT) of the maxillary sinuses was performed after 3 years of graft healing to allow examination of the recipient sites.

Study V. Nano-crystalline-diamond particle-modification of DBB and BCP particles was carried out through different steps of preparation including grinding and ultrasonic techniques. Scanning electron microscopy (SEM) was carried out after 24 hours and 3 days. Real time-polymerase chain reaction (PCR) was carried out after 3 days, 1 week and 2 weeks of incubation. The following osteoblast differentiation markers were analyzed: alkaline phosphatase (ALP), osteocalcin (OC), bone morphogenetic protein type 2 (BMP-2) and integrin alpha 10 (ITGA 10).

Results: In paper I, the results revealed a similar degree of bone formation and bone-to-implant contact around sandblasted and acid-etched microimplants placed in sinuses augmented with BCP or DBB. No obvious signs of resorption of the BCP and DBB particles were noticed. There was a significantly higher amount of DBB particles in contact with newly formed bone compared to BCP (p=.007).

In paper II, the median Ca/P ratios (atomic %), determined from >200 discreet sites within residual graft particles and adjacent bone were analysed. The difference between the median values for BCP and DBB and for BCP-augmented bone compared with DBB-augmented bone were statistical significant (p=.028 in each case). The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of β-TCP and reprecipitation on the surface of calcium-deficient hydroxyapatite.

In paper III, the results revealed that no implant placed in residual bone was lost, one implant placed in BCP was lost after 3 months of functional loading due to infection, and one implant placed in DBB was lost only a few weeks after insertion due to lack of initial instability. The overall implant survival rate was 96.8%. Success rates for implants placed in BCP and DBB were 91.7% and 95.7% respectively. No significant differences in marginal bone loss were found around implants placed in BCP, DBB or residual bone respectively.

In paper IV, it was shown that after 36 months (range; 36 to 37 months) of functional loading the overall implant survival rate was 96.8%. Success rates for implants placed in BCP, DBB and residual bone were 91.7%, 95.7% and 86.7% respectively. No significant difference was found between implants placed in BCP, DBB and residual bone. The corresponding histological evaluation after 3 years of graft healing showed BCP particles under different levels of dissolution. Dissolution was mostly observed on the edges of the BCP particles but in some cases the entire particle was dissolving. In contrast, DBB particles showed no signs of resorption. The percentage of graft particles in contact with newly formed bone was not significantly different after 3 years of healing for BCP and DBB.

In paper V, cellular responses were evaluated in terms of attachment and differentiation. SEM after 24 hours and 3 days of incubation disclosed similar cell attachment and spreading for nDP-modified and non-modified DBB and BCP particles. Real-time PCR revealed significant up-regulation of mRNA expression of ALP and OC and by HOB grown on nDP-modified DBB and BCP-particles after 1 and 2 weeks compared to non-modified particles. A significant down-regulation of BMP-2 on nDP-modified DBB and a significant up-regulation of BMP-2 on DP-modified BCP was disclosed for HOB in relation to un-modified particles. Cell adhesion marker ITGA 10 showed significant down-regulation in the mRNA level for both nDP-modified groups after 2 weeks of incubation (mDP-BCP (p<.01) and nDP-DBB (p<.05) compared to the non-modified materials.

Conclusion: It is concluded that BCP can be used for maxillary floor augmentation and later placement of dental implants producing equal results to those for DBB. Nevertheless, the initial HA/β-TCP ratio in BCP might not be optimized for cell adhesion, which can affect the early healing phase. Furthermore, the results indicate that BCP is not optimized for gene expression in its present form and that nDP-modified BCP enhances the osteoblast phenotype suggesting that these scaffolds are appropriate cell carriers, superior to non-modified BCP particles. Surface modification of bone substitutes is a new interesting field in bone tissue engineering (BTE). Nevertheless, it´s still unclear if the modification will have any clinical impact.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press , 2012. , 63 p.
Series
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1274
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:liu:diva-72938ISBN: 978-91-7393-026-0 (print)OAI: oai:DiVA.org:liu-72938DiVA: diva2:463811
Public defence
2012-01-27, Berzeliussalen, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2011-12-12 Created: 2011-12-12 Last updated: 2011-12-16Bibliographically approved
List of papers
1. Clinical Histology of Microimplants Placed in Two Different Biomaterials
Open this publication in new window or tab >>Clinical Histology of Microimplants Placed in Two Different Biomaterials
2009 (English)In: INTERNATIONAL JOURNAL OF ORAL and MAXILLOFACIAL IMPLANTS, ISSN 0882-2786, Vol. 24, no 6, 1093-1100 p.Article in journal (Refereed) Published
Abstract [en]

Purpose: This randomized, controlled study was designed to compare bone formation around microimplants with a sandblasted, acid-etched surface placed at the time of maxillary sinus floor augmentation with a synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB). Materials and Methods: Nine completely edentulous patients and two partially edentulous patients (six women, five men) with a mean age of 67 years (range, 50 to 79 years) requiring bilateral sinus augmentation were included in the study. The patients were randomized for augmentation with BCP (test) in one side and DBB (control) in the contralateral side. At the time of augmentation, one microimplant on each side was placed vertically from the top of the alveolar crest, penetrating the residual bone and the grafting material. After 8 months of graft healing, at the time of ordinary implant placement, all 22 microimplants were retrieved with a surrounding bone core for histologic analyses. Results: The bone-to-implant contact in the BCP group was 64.6% +/- 9.0%, versus 55.0% +/- 16.0% for the DBB group. The difference was not significant. The corresponding values for the area of newly formed bone in the biopsies were 41.1% +/- 9.8% and 41.6% +/- 14.0% for BCP and DBB, respectively. There were significantly more DBB particles in contact with newly formed bone than BCP particles (87.9 +/- 18.2% versus 53.9 +/- 26.1%; Wilcoxon rank sum test; P = .007). Conclusion: In this randomized, controlled clinical trial, new bone formation and bone-to-implant contact around microimplants with a sandblasted, acid-etched surface was found to be equivalent between sinuses augmented with BCP or DBB. Significantly more DBB particles than BCP particles were in contact with newly formed bone, but the clinical relevance of this has yet to be established.

Keyword
biphasic calcium phosphate, bone substitutes, deproteinized bovine bone, histology, microimplants, sinus floor augmentation
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-53440 (URN)000273295800014 ()20162114 (PubMedID)
Available from: 2010-01-22 Created: 2010-01-22 Last updated: 2011-12-12
2. Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate
Open this publication in new window or tab >>Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate
2010 (English)In: Clinical Oral Implants Research, ISSN 0905-7161, E-ISSN 1600-0501, Vol. 21, no 9, 924-930 p.Article in journal (Refereed) Published
Abstract [en]

Objectives To compare resorption of a synthetic biphasic calcium phosphate (BCP) bone-graft substitute with deproteinized bovine bone (DBB) used for human maxillary sinus augmentation. Materials and methods Eleven patients underwent bilateral maxillary sinus floor augmentation with DBB in one side and a BCP (40% beta-tricalcium phosphate (beta-TCP) and 60% hydroxyapatite) in the contralateral side. Simultaneously, with the augmentation on each side a microimplant was placed vertically from the top of the alveolar crest penetrating the residual bone and the grafting material. Eight months after initial surgery the microimplants were retrieved with a surrounding bone core. The composition of residual graft material and surrounding bone was analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy. Results Residual graft material of both types was present as 10-500 mu m particles in direct contact with, or completely surrounded by, newly formed bone; smaller particles were also present in non-mineralized tissue. In the case of BCP the bone-graft substitute interface showed evidence of superficial disintegration of particles into individual grains. Median Ca/P ratios (at.%), determined from andgt; 200 discreet sites within residual graft particles and adjacent bone, were: DBB: 1.61 (confidence interval [CI] 1.59-1.64); BCP: 1.5 (CI 1.45-1.52); DBB-augmented bone: 1.62 (CI 1.59-1.66); BCP-augmented bone: 1.52 (CI 1.47-1.55); P=0.028 for DBB vs. BCP and DBB- vs. BCP-augmented bone. The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of beta-TCP and reprecipitation on the surface of calcium-deficient hydroxyapatite. Conclusion The beta-TCP component of BCP may be gradually substituted by calcium-deficient hydroxyapatite over the healing period. This process and superficial degranulation of BCP particles may influence the progress of resorption and healing. To cite this article:Lindgren C, Hallman M, Sennerby L, Sammons R. Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate.

Place, publisher, year, edition, pages
Blackwell Publishing Ltd, 2010
Keyword
bone implant interactions, bone substitutes, sinus elevation
National Category
Social Sciences
Identifiers
urn:nbn:se:liu:diva-58655 (URN)10.1111/j.1600-0501.2010.01933.x (DOI)000280630200007 ()
Available from: 2010-08-22 Created: 2010-08-20 Last updated: 2017-12-12Bibliographically approved
3. A Prospective 1-Year Clinical and Radiographic Study of Implants Placed after Maxillary Sinus Floor Augmentation with Synthetic Biphasic Calcium Phosphate or Deproteinized Bovine Bone
Open this publication in new window or tab >>A Prospective 1-Year Clinical and Radiographic Study of Implants Placed after Maxillary Sinus Floor Augmentation with Synthetic Biphasic Calcium Phosphate or Deproteinized Bovine Bone
2012 (English)In: Clinical Implant Dentistry and Related Research, ISSN 1523-0899, E-ISSN 1708-8208, Vol. 14, no 1, 41-50 p.Article in journal (Refereed) Published
Abstract [en]

Background: The technique of using bone grafts or different biomaterials for augmentation of the maxillary sinus prior to implant placement is well accepted by clinicians. However, clinical documentation of some bone substitutes is still lacking. Purpose: This prospective study was designed to evaluate the success rate of implants placed after maxillary sinus augmentation with a novel synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB), the latter acting as control. Material and Methods: Nine edentulous patients and two partially edentulous patients with a mean age of 67 years with a bilateral need for sinus augmentation, <5 mm residual bone in the floor of the sinus and a crestal width ≥4 mm, were included in the study. After bilateral elevation of the Schneiderian membrane, all patients were randomized for augmentation with synthetic BCP in one side and DBB in the contralateral side. After 8 months of graft healing, 62 implants with an SLActive surface were placed. Implant survival, graft resorption, plaque index, bleeding on probing, sulcus bleeding index, probing pocket depth, and implant success rate were evaluated after 1 year of functional loading. Results: After a mean of 118 days, all patients received their fixed prosthetic constructions. One implant was lost in each biomaterial, giving an overall survival rate of 96.8%. Success rates for implants placed in BCP and DBB were 91.7 and 95.7%, respectively. No significant difference in marginal bone loss was found around implants placed in BCP, DBB, or residual bone, respectively. The mean graft resorption was 0.43 mm (BCP) and 0.29 mm (DBB). Conclusion: In this limited study, implant success rate was not dependent on the biomaterial used for maxillary sinus augmentation. Similar results were found after 1 year of functional loading for implants placed after sinus augmentation using BCP or DBB.

Place, publisher, year, edition, pages
Wiley, 2012
Keyword
augmentation, Bio-Oss®sinuslift, bone substitutes, BoneCeramic®, dental implants
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-66971 (URN)10.1111/j.1708-8208.2010.00224.x (DOI)000299412900003 ()20491816 (PubMedID)
Available from: 2011-03-23 Created: 2011-03-23 Last updated: 2017-12-11Bibliographically approved
4. A 3-year clinical follow-up of implants placed in 2 differentbiomaterials used for sinus augmentation
Open this publication in new window or tab >>A 3-year clinical follow-up of implants placed in 2 differentbiomaterials used for sinus augmentation
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Purpose: The aims of the present study were to compare a novel biphasic calcium phosphate (BCP) with deproteinized bovine bone (DBB) used for maxillary sinus floor augmentation (MSFA) in a split mouth design, and to perform a clinical follow-up of placed dental implants.

Material and Methods: Nine completely edentulous patients and two partially edentulous patients with a mean age of 67 years requiring bilateral sinus augmentation were included in the study. The patients were randomized for augmentation with BCP (test) and DBB (control) in the contralateral side. After 8 months of graft healing, 62 implants with an SLActive® surface (Strauman®, Basel, Switzerland) were placed. After 3 years of graft healing core biopsies were obtained from the grafted areas for histological and histomorphometrical analysis. After 3 years of functional implant loading, implant survival/success rate, clinical indexes, radiographical examination and resonance frequency analysis (RFA) wereperformed.

Results: The mean values of the area of newly formed bone in the biopsies was 29% ±14.3% and 32% ± 18.0% for BCP and DBB respectively and graft particles in contact with bone in the BCP group was 38% ± 10.9% compared to 44% ± 12.1% for the DBB group, showing no significant differences between the groups. The mean values of the area of BCP particles and DBB particles were 20% ± 7.5% and 24% ± 13.5% respectively (non-significant).

Irrespective of particles used, one dental implant was lost from each group, giving an overall implant survival rate of 96.8% after 3-years of loading. Conclusion: The results of this prospective 3-year clinical and histological follow up demonstrated a similar amount of newly formed bone irrespectively of the used biomaterial. The choice of biomaterial does not seem to influence the survival rates of the implants.

Keyword
Biphasic calcium phosphate, deproteinized bovine bone, histology, implants, sinus floor augmentation
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-72936 (URN)
Available from: 2011-12-12 Created: 2011-12-12 Last updated: 2011-12-12Bibliographically approved
5. Surface modified biphasic calcium phosphate-particles enhance expression of bone markers in osteoblast-like cells
Open this publication in new window or tab >>Surface modified biphasic calcium phosphate-particles enhance expression of bone markers in osteoblast-like cells
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Objectives: The aim of the present in vitro study was to evaluate the response of human osteoblast-like cells (HOB) to nano-crystalline-diamond-particle-modified (nDP-modified) and un-modified (control) deproteinized bovine bone (DBB) and biphasic calcium phosphate (BCP) scaffolds.

Materials and methods: nDP-modification of DBB and BCP- particles was carried out through different steps of preparation including grinding and  ultrasonic technique. In each experiment, 100 mg materials from each of the 4 groups (nDP-modified DBB, nDP-modified BCP, un-modified DBB and un-modified BCP) were plated into a 48 well cell culture plate and 200.000 cells/well were seeded onto the materials. Scanning electron microscopy (SEM) was carried out after 24 hours and 3 days. Real time-polymerase chain reaction (PCR) was carried out after 3 days, 1 week and 2 weeks of incubation. The following markers were analyzed; alkaline phosphatase (ALP), osteocalcin (OC), bone morphogenetic protein type 2 (BMP-2) and integrin alpha 10 (ITGA 10). The general tendency of DBB and BCP was compared.

Results: Cellular responses were evaluated in terms of attachment and differentiation. SEM after 24 hours and 3 days of incubation disclosed similar cell attachment and spreading for nDP-modified and non-modified DBB and BCP particles. Real-time PCR revealed significant up-regulation of mRNA expression of ALP and OC by HOB grown on nDP-modified DBB and BCP-particles after 1 and 2 weeks compared to non-modified  particles. A significant down-regulation of BMP-2 on nDP-modified DBB and a significant up-regulation of BMP-2 on nDP-modified BCP were disclosed for HOB in relation to un-modified particles. Cell adhesion marker ITGA 10 showed significant down-regulated in the mRNA level for both nDP-modified groups after 2 weeks of incubation (nDP-BCP (p<.01) and nDP-DBB (p<.05) compared to the non-modified materials.

Conclusion: nDP-modified BCP-particles seem to enhance the expression of osteogenic markers in HOB in vitro. The results indicate that nDP-modified BCP enhance the osteoblast phenotype and suggest that these scaffolds might be appropriate cell carriers, superior to nonmodified BCP-particles. The osteogenic markers of OC and ALP were increased for nDPmodified DBB particles but BMP-2 was down regulated in relation to non-modified DBB particles.

Keyword
Tissue engineering, scaffolds, gene expression, human osteoblast-like cells, biphasic calcium phosphate, deproteinized bovine bone
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:liu:diva-72937 (URN)
Available from: 2011-12-12 Created: 2011-12-12 Last updated: 2011-12-12Bibliographically approved

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