Marcel Obrecht

Institut Straumann AG, Bâle, Basel-City, Switzerland

Are you Marcel Obrecht?

Claim your profile

Publications (10)23.45 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Dental implant surface technology has evolved from a relatively smooth machined implant surface for osseointegration to more roughened osteoconductive surfaces. Recent studies suggest that peri-implant soft tissue inflammation with progressive bone loss (ie, peri-implantitis) is becoming a prevalent condition. One possibility that could explain such a finding is that more bacterial plaque forms on the roughened implant and abutment surfaces, which may result in the peri-implant inflammation in the soft tissues. This study compared 36 tissue-level implants with a machined transmucosal collar to 36 implants with a relatively roughened (SLActive) transmucosal surface in the dog. The implants were evaluated histologically and histomorphometrically after 3 and 12 months of loading. The results demonstrated that the connective tissue contact was similar between the two implant types but that the junctional epithelium and biologic width dimensions were greater around the implants with the machined collars. Interestingly, the amount of inflammation was similar between the two implant types. Slightly more bone formation and more mature collagen formation occurred around the implants with the roughened collars compared to the implants with machined collars. These results suggested that even if more plaque biofilm forms on the implants with the roughened SLActive surface compared to the machined surface, there is no biologic consequence related to the amount of inflammation or bone loss. In fact, the roughened surface promoted bone formation (was more osteoconductive) and more mature soft collagenous connective tissue.
    The International journal of periodontics & restorative dentistry 11/2014; 34(6):773-9. · 1.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: The aim of this study is to assess the ability of a novel nonwovens-based gradient gelatine-polycaprolactone nonwoven membrane (GPM) to restore oral soft tissue defects by evaluating this medical device using complex interactive organotypic fibroblast-keratinocytes cell systems. Method: The GPM was produced via electrospinning. The gelatine fibres of the GPM were in situ crosslinked during the spinning process. Interactive organotypic cell systems were established by cultivating human gingival keratinocytes (HGK) on the denser side of the GPM and human gingival fibroblast (HGF) on the less dense side. The cell compartments were analysed by immunohistochemistry and scanning electron microscopy (SEM). Additionally, the GPM was applied in a pilot minipig study, where the clinical wound healing was evaluated for a period of 4 weeks after operative procedure. Results: SEM and actin / integrin fluorescence showed a typical morphology of HGF and HGK and visualised in addition cell adhesion to the fibres network. Deposited extracellular matrix was observed on HGF membrane that migrated into the fibre network. The HGK formed a stratified epithelial equivalent. Immunohistological analysis revealed tissue-specific distribution of vimentin in the connective tissue compartment and an increase of keratin 1/10 and involucrin expression over time in the epithelial equivalent. In addition, the suitability of this novel membrane for oral soft tissue regeneration was encouraged by a pilot study in the minipig model, where an almost complete epithelial wound closure was observed following a surgically-induced dehiscence. Conclusion: Preclinical validation of the novel GPM by using organotypic interactive cell systems and the pilot minipig study suggested this membrane as promising and versatile medical device for treatment of oral soft tissue defects.
    2014 IADR/PER Congress; 09/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Implant dentistry demonstrated its reliability in treating successfully an increased amount of patients with dental implants exhibiting hydrophilic (modSLA) or non-hydrophilic (SLA) surfaces. Objectives of this minipig study consisted in assessing bone regeneration at both types of dental implants in a new experimental model (lateral bone defects) by implementing a convergent analysis approach combining histology and contact radiography. In six adult female minipigs standardized acute alveolar defects were created, then receiving two implants in the mandibles bilaterally (modSLA and SLA, one of each combined with Guided Bone Regeneration). Animals were sacrificed after 28 days of healing. Mid-crestal specimen were analysed assessing missing BIC to implant shoulder (fBIC); vertical bone growth upon implant surface, bone:tissue ratio and grafting material area occupied by material remnants for GBR sites. Values obtained from both analyses were compared and statistical correlations scrutinized. Although dimensions of mean differences and adjusted means given by radiographic method were lower than histological ones, comparison of different implants yielded similar results. Statistical analyses of correlation and concordance coefficients used to evaluate radiological method of measurement showed high level of concordance (concordance coefficient=0.912 and correlation coefficient=0.939) for fBIC. Similar results were observed for vertical new bone and for remnants of graft. Discrepancies for new bone and for mineralized tissue resulted in concordance coefficient of 0.182 and 0.054. The results indicate that contact x-rays can be used for morphometric assessments regarding defect fill; however, histological staining remains beneficial if greater resolution for distinguishing qualitative differences in the tissues is required.
    Annals of anatomy = Anatomischer Anzeiger: official organ of the Anatomische Gesellschaft 05/2014; · 1.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to investigate bone regeneration following application of a novel biphasic calcium phosphate (BCP I) composed of microstructured granules of 90% β-tricalcium phosphate (β-TCP)/10% hydroxyapatite (HA) compared to BCP non-microstructured biphasic calcium phosphate with a composite of 60% hydroxyapatite/40% β-TCP (BCP II) and a deproteinized bovine bone mineral (DBBM) at surgically created defects in the mandible of minipigs in a combined approach with guided bone regeneration (GBR). Sixteen minipigs were used for the study. Lower premolars P2, P3, P4 and first molar M1 were extracted. Following 3 months of healing, two defects with a width and depth of 7 mm were created bilaterally in the mandible. The different grafting materials were randomly placed in the created defects and covered by means of a collagen membrane. After 3 and 8 weeks, biopsies were sampled. All specimens were evaluated with descriptive histology and histomorphometric evaluations complemented by micro-CT scan analysis. All three biomaterials presented with higher bone volume at 8 weeks compared to 3 weeks (P < 0.0442). BCP I and DBBM demonstrated a significant higher amount of bone formation compared to BCP II at 8 weeks (P < 0.0328). BCP I also demonstrated a significant higher percentage of remaining graft volume compared to the other test groups both at 3 and 8 weeks (P < 0.0001 to P < 0.0003). Congruently, defects containing BCP I showed a significant higher amount of mineralized tissue compared to the other groups. All the three test materials performed well with regard to bone formation at 8 weeks. BCP I showed significant higher amounts of newly formed bone despite a higher remaining graft volume compared to the other groups. With regard to the regenerative outcome, all the three materials can be recommended for clinical use.
    Clinical Oral Implants Research 03/2014; · 3.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Standard preclinical assessments in vitro have often limitations regarding their transferability to human beings, mainly evoking by their non-human and tissue-different/non-tissue-specific source. Here we aimed at employing tissue-authentic simple and complex interactive fibroblast-epithelial cell systems and their in vivo-relevant biomarkers for preclinical in vitro assessment of nonwovens-based gelatin/polycaprolactone membranes (NBM) for treatments of soft tissue defects. NBMs were assembled of electrospun gelatin and polycaprolactone nanofibre nonwovens. Scanning electron microscopy (SEM) in conjunction with actin/focal contact integrin fluorescence revealed successful adhesion and proper morphogenesis of keratinocytes and fibroblasts, together with cells'-derived extracellular matrix deposits. The "feel-good factor" of cells under study on the NBM was substantiated by forming a confluent connective tissue entity, concomitant with a stratified epithelial equivalent. Immunohistochemistry proved tissue-authenticity over time by abundance of the biomarkers vimentin in the connective tissue entity, and chronological increase of keratins K1/10 and involucrin expression in epithelial equivalents. Suitability of the novel NBM as wound dressing was evidenced by an almost completion of epithelial wound closure in a pilot mini-pig study, following a surgical intervention-caused gingival dehiscence. In summary, preclinical assessment by tissue-authentic cell systems and the animal pilot study revealed the NBM as an encouraging therapeutic medical device for prospective clinical applications.
    Tissue Engineering Part A 02/2014; · 4.64 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The aim of the study was to introduce a novel three-dimensional (3D) method to quantify the relative amount of different tissue components in bone substitute-treated defects by means of integration of confocal laser imaging into micro-computed tomography (μCT) analysis. One standardized semisaddle intraosseous defect was prepared in the mandibles of six minipigs and scanned by an optical scanner to capture the surface of the fresh defect in a 3D manner. Subsequently, all the defects were filled with a biphasic calcium phosphate material. The animals were divided into two groups of three animals each, which were allowed to heal for 3 and 8 weeks, respectively. μCT analysis followed the two healing periods and was performed on all defect locations. The data from optical scanning and μCT were used for three-dimensional evaluation of bone formation, nonmineralized tissue ratio, and graft degradation. The integration of confocal laser scanning into μCT analysis through a superimposition imaging procedure was conducted using the software Amira (Mercury Computer Systems, Chelmsford, MA, USA). The feasibility of combining the confocal imaging into μCT data with regard to obtaining accurate 3D quantification was demonstrated. The amount of tissue components was identified and quantified in all the investigated samples. Quantitative analysis demonstrated that a significant increase in the amount of bone filling the defect was observed in vivo (p < 0.02) while a significant decrease in the amount of nonmineralized tissue occurred (p < 0.04). No difference in the amount of residual grafting material was detected between 3 and 8 weeks in vivo (p > 0.38). The combination of confocal imaging and micro-computed tomography techniques allows for analysis of different tissue types over time in vivo. This method has revealed to be a feasible alternative to current bone regeneration quantification methods. Assessment of bone formation in a large animal model is a key step in assessing the performance of new bone substitute materials. Reliable and accurate methods are needed for the analysis of the regenerative potential of new materials.
    Clinical Oral Investigations 08/2013; · 2.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: OBJECTIVE: Implant surface properties have long been identified as an important factor to promote osseointegration. The importance of nanostructures and hydrophilicity has recently been discussed. The aim of this study was to investigate how nanostructures and wettability influence osseointegration and to identify whether the wettability, the nanostructure or both in combination play the key role in improved osseointegration. MATERIALS AND METHODS: Twenty-six adult rabbits each received two Ti grade 4 discs in each tibia. Four different types of surface modifications with different wettability and nanostructures were prepared: hydrophobic without nanostructures (SLA), with nanostructures (SLAnano); hydrophilic with two different nanostructure densities (low density: pmodSLA, high density: SLActive). All four groups were intended to have similar chemistry and microroughness. The surfaces were evaluated with contact angle measurements, X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and interferometry. After 4 and 8 weeks healing time, pull-out tests were performed. RESULTS: SLA and SLAnano were hydrophobic, whereas SLActive and pmodSLA were super-hydrophilic. No nanostructures were present on the SLA surface, but the three other surface modifications clearly showed the presence of nanostructures, although more sparsely distributed on pmodSLA. The hydrophobic samples showed higher carbon contamination levels compared with the hydrophilic samples. After 4 weeks healing time, SLActive implants showed the highest pull-out values, with significantly higher pull-out force than SLA and SLAnano. After 8 weeks, the SLActive implants had the highest pull-out force, significantly higher than SLAnano and SLA. CONCLUSIONS: The strongest bone response was achieved with a combination of wettability and the presence of nanostructures (SLActive).
    Clinical Oral Implants Research 06/2013; · 3.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objective: To evaluate the effect of perforated scaffold retainers used in conjunction with dental implants and osteoinductive scaffolds to regenerate vertical supracrestal alveolar bone in an intraoral minipig model. Materials and Methods: Three months after extraction of mandibular premolars and first molars from six adult minipigs, two titanium (Ti) custom implants were placed bilaterally in the edentulous mandibles for a total of four implants per animal. The upper 2.5 mm of the implant was left above bone level and covered with: (1) wide-neck healing caps; (2) perforated, overhanging custom scaffold retainers (umbrellas); or (3) scaffold retainers and demineralized minipig bone allograft (DBM) and nonglycosylated bone morphogenetic protein 2 (ng/rhBMP-2)-treated implants. All constructs were submerged beneath soft tissue flaps for 8 weeks. Two dental implant surfaces were compared: SLA and SLActive. Samples were retrieved after 8 weeks and analyzed by radiography, micro-computed tomography and histomorphometry. Results: All implants were stable at the end of the experiment. Histomorphometry revealed that the use of the scaffold-retaining umbrellas led to increased, but not statistically significant, vertical bone regeneration as compared to the use of wide-neck healing caps (1.0 ± 0.4 mm vs 0.6 ± 0.3 mm). The combination of DBM and ng/rhBMP-2 released from the surface of the SLA implant resulted in the greatest amount of vertical bone regeneration (2.1 ± 0.2 mm). The bone-to-implant contact was similar for all groups. Mucosal dehiscence areas with healing cap or custom scaffold retainer exposures were reduced in the presence of ng/rhBMP-2. Conclusions: The combined use of custom perforated Ti scaffold retainers, DBM, and ng/rhBMP-2 regenerated a substantial amount of vertical supracrestal alveolar bone around Ti implants in an intraoral minipig model.
    The International journal of oral & maxillofacial implants 03/2013; 28(2):432-43. · 1.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study evaluates a newly developed titanium-zirconium implant (TiZr), comparing it to a commercially available pure titanium (Ti) implant subjected to the same surface treatment. In nine dogs, 12 implants (six TiZr and six Ti) were randomly placed in the mandible with the implant shoulder at the bone crest and subjected to submerged healing. Standardized radiographs were taken after implantation, and at the sacrifice of 2 weeks (three dogs), 4 weeks (three dogs), and 8 weeks (three dogs). Histologic and histomorphometric measurements were performed on non-decalcified histologic sections. The main outcome measures included the first bone-implant contact (fBIC) and BIC over time. For statistical analysis, Wilcoxon signed-rank test and mixed model regressions were applied. From baseline to 8 weeks, a mean bone loss of 0.09 ± 0.33 mm for TiZr and a gain of 0.02 ± 0.33 mm for Ti were calculated radiographically. The number of implants with the fBIC coronal to the reference point (implant shoulder) gradually increased over time, reaching 39% of all TiZr implants and 50% of all Ti implants at 8 weeks. The mean fBIC values for Ti and TiZr were 0.29 ± 0.42 mm and 0.26 ± 0.32 mm (2 weeks), -0.01 ± 0.20 mm and 0.10 ± 0.28 mm (4 weeks), and -0.06 ± 0.22 mm and 0.08 ± 0.30 mm (8 weeks), respectively. The mean BIC values peaked at 86.9% ± 6.8% (8 weeks) for TiZr and at 83.4% ± 5.9% (4 weeks) for Ti. No statistically significant differences were observed at any time point. TiZr and Ti bone level implants with chemically-modified, sandblasted, and acid-etched surfaces performed similarly in regards to osseointegration in this unloaded canine study.
    Journal of Periodontology 10/2011; 82(10):1453-61. · 2.40 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: A newly developed titanium-zirconium implant (TiZr) compared with a commercially available pure titanium (Ti) implant subjected to the same surface treatment is evaluated. Methods: In 9 dogs, 12 implants (6 TiZr, 6 Ti) were randomly placed in the mandible with the implant shoulder at the bone crest and subjected to submerged healing. Standardized x-rays were taken following implantation, and at the sacrifice of 2 weeks (3 dogs), 4 weeks (3 dogs), and 8 weeks (3 dogs). Histologic and histomorphometric measurements were performed on non-decalcified histological sections. The main outcome measures included the first bone-to-implant contact (fBIC) and the bone-to-implant contact (BIC). For statistical analysis, the Wilcoxon signed rank test and mixed model regressions were applied. Results: From baseline to 8 weeks, a mean bone loss of 0.09±0.33mm for TiZr and a gain of 0.02±0.33mm for Ti were calculated radio graphically. The number of implants with the fBIC coronal to the reference point (implant shoulder) gradually increased over time, reaching 39% of all TiZr implants and 50% of all Ti implants at 8 weeks. The mean fBIC values for Ti and TiZr were 0.29±0.42mm,and 0.26±0.32mm (2 weeks), -0.01±0.20mm and 0.10±0.28mm (4 weeks), and -0.06±0.22mm and 0.08±0.30mm (8 weeks), respectively . The mean BIC values peaked at 86.9±6.8% (8 weeks) for TiZr, and at 83.4±5.9% (4 weeks) for Ti. No statistically significant differences were observed at any time-point. Conclusions: TiZr and Ti bone level implants with a chemically modified sandblasted and acid etched surface performed similarly in regards to osseointegration in this unloaded canine study.
    Journal of Periodontology 02/2011; · 2.40 Impact Factor