Micro-angiogenic patterns around orthodontic implants migrating in bone: A micro-CT study in the rat tail model.

AIM: Recent studies revealed that implants can migrate in bone when subjected to continuous loading. Since this process is suspected to be accompanied by bone remodelling, which requires blood vessel formation, the present work aimed at assessing the micro-angiogenic patterns around migrating implants. MATERIALS AND METHODS: In 16 rats, two customized implants were placed in a single tail vertebra and connected with contraction springs (forces: 0 N, 0.5 N, 1.0 N, 1.5 N). After 2 or 8 weeks of loading, the animals were scanned by micro-CT before and after vasculature perfusion with a silicone rubber. Vessels were segmented by subtraction of the two micro-CT scans. Vessel thickness (V.Th), vessel volume per total volume (VV/TV), and vascular spacing (V.Sp) were assessed in a peri-implant volume of interest (VOI) around each implant. RESULTS: At 2 weeks of loading, force magnitude was significantly associated with VV/TV and V.Th values (χ2  = 10.942, p < .001 and χ2  = 6.028, p = .010, respectively). No significant differences were observed after 8 weeks of loading. CONCLUSIONS: Within the limitations of an animal study, peri-implant vessel thickness and density were associated with force magnitude in the early loading phase, whereas effects diminished after 8 weeks of loading.

Rodentibacter haemolyticus sp. nov. isolated from laboratory rodents.

Nine strains of a Rodentibacter-related bacterium were isolated over a period of 38 years from a laboratory mouse (Mus musculus), seven laboratory rats (Rattus norvegicus) and a Syrian hamster (Mesocricetus auratus) in Düsseldorf and Heidelberg, Germany. The isolates are genotypically and phenotypically distinct from all previously described Rodentibacter species. Sequence analysis of 16S rRNA and rpoB gene sequences placed the isolates as a novel lineage within the genus Rodentibacter. In addition to the single-gene analysis, the whole genome sequence of the strain 1625/19T revealed distinct genome-to-genome distance values to the other Rodentibacter species. The genomic DNA G+C content of strain 1625/19T was 40.8 mol% within the range of Rodentibacter. At least six phenotypic characteristics separate the new isolates from the other Rodentibacter species, with Rodentibacter heylii being the most closely related. In contrast to the latter, the new strains display ß-haemolysis and are ß-glucuronidase, d-mannitol and sorbitol positive, but fail to produce lysine decarboxylase and trehalose. The genotypic and phenotypic differences between the novel strains and the other closely related strains of the genus Rodentibacter indicate that they represent a novel species within the genus Rodentibacter, family Pasteurellaceae, for which the name Rodentibacter haemolyticus sp. nov. is proposed. The type strain 1625/19T, (=DSM 111151T=CCM 9081T), was isolated in 2019 from the nose of a laboratory mouse (Mus musculus) in Düsseldorf, Germany.

Does a Red House Affect Rhythms in Mice with a Corrupted Circadian System?

The circadian rhythms of body functions in mammals are controlled by the circadian system. The suprachiasmatic nucleus (SCN) in the hypothalamus orchestrates subordinate oscillators. Time information is conveyed from the retina to the SCN to coordinate an organism's physiology and behavior with the light/dark cycle. At the cellular level, molecular clockwork composed of interlocked transcriptional/translational feedback loops of clock genes drives rhythmic gene expression. Mice with targeted deletion of the essential clock gene Bmal1 (Bmal1-/-) have an impaired light input pathway into the circadian system and show a loss of circadian rhythms. The red house (RH) is an animal welfare measure widely used for rodents as a hiding place. Red plastic provides light at a low irradiance and long wavelength-conditions which affect the circadian system. It is not known yet whether the RH affects rhythmic behavior in mice with a corrupted circadian system. Here, we analyzed whether the RH affects spontaneous locomotor activity in Bmal1-/- mice under standard laboratory light conditions. In addition, mPER1- and p-ERK-immunoreactions, as markers for rhythmic SCN neuronal activity, and day/night plasma corticosterone levels were evaluated. Our findings indicate that application of the RH to Bmal1-/- abolishes rhythmic locomotor behavior and dampens rhythmic SCN neuronal activity. However, RH had no effect on the day/night difference in corticosterone levels.

Chronic stable heart failure model in ovine species.

Establishing a chronic heart failure (HF) model is challenging, particularly in the ovine model. The aim of this study was to establish a reproducible model of HF in an ovine model. Seventeen sheep were operated using the left thoracotomy approach. Chronic HF was induced through ligation of the diagonal and marginal branches only. Perioperative hemodynamic and echocardiographic parameters were compared. A total of (3 ± 1) coronary ligations were used. Thirteen animals survived the procedure and were followed up for (15 ± 5) days. The mean arterial pressure, heart rate (HR), mean pulmonary artery pressure (mPAP), central venous pressure, and cardiac output at baseline and prior to animal sacrifice was (75 ± 14 mmHg) and (68 ± 16 mmHg) P = .261; (72 ± 9 bpm), (100 ± 28 bpm) P = .01; (15 ± 4 mmHg) and (18 ± 5 mmHg) P = .034; (10 ± 6 mmHg) and (8 ± 4 mmHg) P = .326; (3.4 ± 1 L/min) and (3.9 ± 1 L/min) P = .286, respectively. The LVEF at baseline and prior to animal sacrifice was (63 ± 13%) and (43 ± 6%) P = .012. Twelve surviving animals were supported with LVAD in a follow-up procedure. Chronic stable HF in sheep was successively established. Clinical symptoms and drastic increase in the mPAP and HR as well as echo findings were the most sensitive parameters of HF. This reproducible ovine model has proven to be highly promising for research regarding HF.

Leucobacter muris sp. nov., isolated from the nose of a laboratory mouse.

A Gram-stain-positive, rod-shaped, aerobic, non-motile, white, opaque bacterial isolate, designated 924/12T, was isolated from the nose of a laboratory mouse in Düsseldorf, Germany. The 16S rRNA gene sequence analyses indicated the phylogenetic position of the strain within the genus Leucobacter. Similarity levels over 97 % were recorded between the 16S rRNA gene sequence of strain 924/12T and the type strains of the species Leucobacter chironomi DSM 19883T (99.5 %), followed by Leucobacter celersubsp. astrifaciens CBX151T (97.6 %), Leucobacter celersubsp. celer NAL101T (97.5 %), 'Leucobacter kyeonggiensis' F3-P9 (97.5 %), Leucobacter zeae CC-MF41T (97.3 %), Leucobacter chromiiresistens JG31T (97.1 %), Leucobacter triazinivorans JW-1T (97.1 %), Leucobacter corticis 2 C-7T (97.0 %) and Leucobacter aridicolis CIP108388T (97.0 %). DNA-DNA hybridization and whole genomic comparison, mandatory to taxonomically separate strain 924/12T from the type strain of L. chironomi, revealed similarity values of 40.4 and 30.8 %, respectively, thus below the threshold of 70 % recommended differentiating between species. The cell-wall amino acids of the novel isolate were diaminobutyric acid, alanine, glycine, threonine and glutamic acid. The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, glycolipid and one unknown lipid, whereas the predominant menaquinones were MK-11 and MK-10. The genomic DNA G+C content of strain 924/12T was 70.6 mol%. Phylogenetic analyses based on the 16S rRNA gene sequences and the phenotypical differences between strain 924/12T and the other closely related type strains of the genus Leucobacter indicated that strain 924/12T represents a novel species within the genus Leucobacter, family Microbacteriaceae, for which the name Leucobacter muris sp. nov. is proposed. The type strain is 924/12T (=DSM 101948T=CCM 8761T).

Biomechanical Stability and Osteogenesis in a Tibial Bone Defect Treated by Autologous Ovine Cord Blood Cells-A Pilot Study.

The aim of this study was to elucidate the impact of autologous umbilical cord blood cells (USSC) on bone regeneration and biomechanical stability in an ovine tibial bone defect. Ovine USSC were harvested and characterized. After 12 months, full-size 2.0 cm mid-diaphyseal bone defects were created and stabilized by an external fixateur containing a rigidity measuring device. Defects were filled with (i) autologous USSC on hydroxyapatite (HA) scaffold (test group), (ii) HA scaffold without cells (HA group), or (iii) left empty (control group). Biomechanical measures, standardized X-rays, and systemic response controls were performed regularly. After six months, bone regeneration was evaluated histomorphometrically and labeled USSC were tracked. In all groups, the torsion distance decreased over time, and radiographies showed comparable bone regeneration. The area of newly formed bone was 82.5 ± 5.5% in the control compared to 59.2 ± 13.0% in the test and 48.6 ± 2.9% in the HA group. Labeled cells could be detected in lymph nodes, liver and pancreas without any signs of tumor formation. Although biomechanical stability was reached earliest in the test group with autologous USSC on HA scaffold, the density of newly formed bone was superior in the control group without any bovine HA.

Horizontal mucosal thickness at implant sites as it correlates with the integrity and thickness of the buccal bone plate.

OBJECTIVES: To histologically assess the association between the horizontal mucosal thickness (MT) at implant sites with the integrity and thickness of the buccal bone plate in a canine model. MATERIALS AND METHODS: Two-piece titanium implants were placed at chronic-type lateral ridge defects. The resulting vestibular dehiscence-type defects (vertical dimensions of 2-8 mm) were left untreated. After a submerged healing period of 2 and 8 weeks (n = 6 fox hounds each), dissected blocks were processed for histomorphometrical analyses [e.g. MT, bone thickness (BT) and residual defect length]. RESULTS: Linear regression revealed significant associations between vestibular MT and BT values after 2 (R2  = 0.22, B = -0.37, P < 0.0001) and 8 weeks (R2  = 0.37, B = -0.45, P < 0.001) of healing. CONCLUSION: The present analysis has pointed to an inverse relationship between horizontal MT and BT values at the vestibular aspect of submerged titanium implants. MT was most pronounced in the absence of a buccal bone plate.

Animal models for peri-implant mucositis and peri-implantitis.

The treatment of infectious diseases affecting osseointegrated implants in function has become a demanding issue in implant dentistry. Since the early 1990s, preclinical data from animal studies have provided important insights into the etiology, pathogenesis and therapy of peri-implant diseases. Established lesions in animals have shown many features in common with those found in human biopsy material. The current review focuses on animal studies, employing different models to induce peri-implant mucositis and peri-implantitis.

Efficacy of professionally administered plaque removal with or without adjunctive measures for the treatment of peri-implant mucositis. A systematic review and meta-analysis.

FOCUSED QUESTION: In patients with peri-implant mucositis, what is the efficacy of professionally administered plaque removal (PAPR) with adjunctive measures on changing signs of inflammation compared with PARP alone? MATERIALS AND METHODS: After electronic database and hand search, 19 full-text articles were independently screened by two reviewers. Finally, a total of seven studies fulfilled the inclusion criteria. The weighted mean difference (WMD) in bleeding on probing- (BOP) (primary outcome), gingival index- (GI) and probing pocket depth- (PD) reductions was estimated (random effect model). RESULTS: WMD in BOP reduction between test and control groups amounted to -8.16% [SD = 4.61; p = 0.07; 95% CI (-17.20, 0.88)] not favouring adjunctive antiseptic or antibiotic (local, systemic) therapy over PAPR alone. WMD in GI and PD reductions amounted to -0.12 [SD = 0.13; p = 0.34; 95% CI (-0.38, 0.13)] and -0.056 mm [SD = 0.10; p = 0.60; 95% CI (-0.27, 0.16)] not favouring adjunctive (antiseptics, systemic antibiotics, air abrasive device) over control measures respectively. Most studies evaluated reported on residual BOP and GI scores after therapy. CONCLUSIONS: Adjunctive therapy may not improve the efficacy of PAPR in reducing BOP, GI and PD scores at mucositis sites. Despite clinically important improvements, a complete disease resolution may not be expected by any of the treatment protocols investigated.

Impact of plaque accumulation on the osseointegration of titanium-zirconium alloy and titanium implants. A histological and immunohistochemical analysis.

OBJECTIVES: To evaluate the impact of plaque accumulation on osseointegration at surface enhanced modified hydrophilic titanium-zirconium (TiZr) alloy and titanium (Ti) implants. MATERIALS AND METHODS: TiZr and Ti implants with a sand-blasted, acid etched, and chemically modified endosseous and a machined (M) transmucosal portion were bilaterally (i.e., one implant type on each side) inserted in the maxilla of six foxhounds. In a split-mouth design, experimental mucositis was induced at one randomly assigned side (NPC), while the contralateral side received mechanical plaque removal three times per week (PC). After 16 weeks, tissue biopsies were processed for histological (primary outcome: bone-to-implant contact [BIC]) and immunohistochemical (CD68) analysis. RESULTS: Mean BIC values varied between 81.96% (TiZrM) and 88.72% (TiM) in the NPC group, and between 87.88% (TiM) and 92.69% (TiZrM) in the PC group. Even though BIC values tended to be lower within the endosseous coronal compartment at NPC sites, within group (NPC vs. PC) comparisons failed to reach statistical significance at both types of implants. These non-BIC areas were not associated with any CD68 positive cells. CONCLUSIONS: Osseointegration of both TiZrM and TiM implants was not influenced by plaque accumulation in this experimental model.

Impact of abutment microstructure and insertion depth on crestal bone changes at nonsubmerged titanium implants with platform switch.

OBJECTIVES: To assess the impact of microgrooved abutments and the insertion depth on crestal bone changes at titanium implants with platform switch. MATERIALS AND METHODS: A total of n = 3 titanium implants (conical abutment connection) were inserted in each hemimandible of n = 6 foxhounds with the implant shoulder (IS) located at either epicrestal, supracrestal (+1 mm), or subcrestal (-1 mm) positions and randomly (split-mouth design) connected with machined or partially microgrooved healing abutments. At 20 weeks, tissue biopsies were processed for histological (primary outcome: net bone loss - NET) analyses. RESULTS: Subcrestal positioning of IS tended to be associated with higher mean NET values (mm) at both machined (subcrestal [-0.72 ± 0.32] > epicrestal [-0.34 ± 0.21] > supracrestal [+0.20 ± 0.64]) and microgrooved (subcrestal [-0.48 ± 0.25] > epicrestal [-0.13 ± 0.54] > supracrestal [+0.33 ± 0.58]) abutments. However, these differences failed to reach statistical significance. CONCLUSIONS: The insertion depth may have a direct influence on crestal bone-level changes at both types of abutments investigated.

Immunohistochemical characteristics of regenerated bone after surgical therapy of advanced ligature-induced peri-implantitis defects.

OBJECTIVES: This study seeks to assess and compare immunohistochemical characteristics of regenerated and pristine bone areas following surgical therapy of advanced peri-implantitis. METHODS: At ligature-induced peri-implantitis defects, the intrabony component was filled with a natural bone mineral (NBM), and the supracrestal component was treated by either an equine bone block (EB) or implantoplasty. NBM and EB were soak-loaded with rhBMP-2 or sterile saline. Membrane (i.e., native collagen) protected sites were submerged for 12 weeks. Osteocalcin (OC) and transglutaminase 2 (TG2; angiogenesis) antigen reactivity was assessed within the augmented-(AA) and pristine bone (PB) areas at non-exposed sites (n = 39 defects). RESULTS: In all groups investigated, mean OC (AA, 0.5 ± 0.4 to 1.9 ± 2.9 %/PB, 1.7 ± 2.6 to 3.5 ± 6.5 %) and TG2 (AA, 0.6 ± 0.5 to 1.3 ± 1.5 %/PB, 0.5 ± 0.5 to 1.6 ± 1.9 %) values within AA did not significantly differ from those values assessed within PB (P > 0.05, respectively). CONCLUSIONS: AA formed in different treatment groups may not be considered as qualitatively (i.e., OC and TG2) compromised bone.

Swollen Ampulla as an Indicator of Successful Pregnancy in B6C3F1 Recipient Mice used for Assisted Reproduction.

In vitro fertilization (IVF), embryo cryopreservation, and embryo transfer (ET) are assisted reproductive technologies (ARTs) that are used extensively for the maintenance of mouse models in animal research. Inbred mouse strains with different genetic backgrounds vary in their reproductive performance. Cryopreservation can affect embryo quality and viability, and the genetic background of ET recipients can influence the ET result. In this retrospective study, we analyzed the out- comes of ETs performed in our facility during the last 6 y. We found that B6C3F1 mice with swollen ampullae show almost 3-fold higher pregnancy rates than mice with nonswollen ampullae when either freshly isolated or frozen-thawed embryos are implanted. Implantation of freshly collected embryos in recipients with swollen ampullae led to significantly higher pregnancy rates in comparison to implantation of frozen-thawed embryos, regardless of whether the latter were fertilized in vivo or in vitro. Moreover, we found a significant effect of genetic background on the birth rate; C57BL/6J mice and mice with a mixed genetic background had 34% higher birth rates than did C57BL/6N mice. Within the C57BL/6J group, the birth rates were significantly higher when using fresh in vivo-fertilized embryos, and cryopreservation negatively affected both in vivo- and in vitro-fertilized embryos. The success rate of obtaining one living pup was not significantly different between frozen-thawed and fresh embryos. Overall, a swollen ampulla is a strong indicator for a successful pregnancy, together with the embryo manipulation and genetic background. A better understanding of the factors that affect the reproductive outcome might lead to optimization of the ART protocols and contribute to a reduction in the number of mice used for these procedures.

Pharmacokinetic study on pradofloxacin in the dog - comparison of serum analysis, ultrafiltration and tissue sampling after oral administration.

BACKGROUND: Pradofloxacin, a newly developed 8-cyano-fluoroquinolone, show enhanced activity against Gram-positive organisms and anaerobes to treat canine and feline bacterial infections. The purpose of this cross-over study was to measure the unbound drug concentration of pradofloxacin in the interstitial fluid (ISF) using ultrafiltration and to compare the kinetics of pradofloxacin in serum, ISF and tissue using enrofloxacin as reference. RESULTS: After oral administration of enrofloxacin (5 mg/kg) and pradofloxacin (3 mg/kg and 6 mg/kg, respectively), serum collection and ultrafiltration in regular intervals over a period of 24 h were performed, followed by tissue sampling at the end of the third dosing protocol (pradofloxacin 6 mg/kg). Peak concentrations of pradofloxacin (3 mg/kg) were 1.55±0.31 µg/ml in the ISF and 1.85±0.23 µg/ml in serum and for pradofloxacin (6 mg/kg) 2.71±0.81 µg/kg in the ISF and 2.77±0.64 µg/kg in serum; both without a statistical difference between ISF and serum. Comparison between all sampling approaches showed no consistent pattern of statistical differences. CONCLUSIONS: Despite some technical shortcomings the ultrafiltration approach appears to be the most sensitive sampling technique to estimate pharmacokinetic values of pradofloxacin at the infection site. Pharmacokinetics - Pradofloxacin - Ultrafiltration - Dog - Oral Administration.

Comparison of compositional MRI techniques to quantify the regenerative potential of articular cartilage: a preclinical minipig model after osteochondral defect treatments with autologous mesenchymal stromal cells and unseeded scaffolds.

Background: The field of orthopedics seeks effective, safer methods for evaluating articular cartilage regeneration. Despite various treatment innovations, non-invasive, contrast-free full quantitative assessments of hyaline articular cartilage's regenerative potential using compositional magnetic resonance (MR) sequences remain challenging. In this context, our aim was to investigate the effectiveness of different MR sequences for quantitative assessment of cartilage and to compare them with the current gold standard delayed gadolinium-enhanced MR imaging of cartilage (dGEMRIC) measurements. Methods: We employed ex vivo imaging in a preclinical minipig model to assess knee cartilage regeneration. Standardized osteochondral defects were drilled in the proximal femur of the specimens (n=14), which were divided into four groups. Porcine collagen scaffolds seeded with autologous adipose-derived stromal cells (ASC), autologous bone marrow stromal cells (BMSC), and unseeded scaffolds (US) were implanted in femoral defects. Furthermore, there was a defect group which received no treatment. After 6 months, the specimens were examined using different compositional MR methods, including the gold standard dGEMRIC as well as T1, T2, T2*, and T1ρ techniques. The statistical evaluation involved comparing the defect region with the uninjured tibia and femur cartilage layers and all measurements were performed on a clinical 3T MR Scanner. Results: In the untreated defect group, we observed significant differences in the defect region, with dGEMRIC values significantly lower (404.86±64.2 ms, P=0.018) and T2 times significantly higher (44.24±2.75 ms, P<0.001). Contrastingly, in all three treatment groups (ASC, BMSC, US), there were no significant differences among the three regions in the dGEMRIC sequence, suggesting successful cartilage regeneration. However, T1, T2*, and T1ρ sequences failed to detect such differences, highlighting their lower sensitivity for cartilage regeneration. Conclusions: As expected, dGEMRIC is well suited for monitoring cartilage regeneration. Interestingly, T2 imaging also proved to be a reliable cartilage imaging technique and thus offers a contrast agent-free alternative to the former gold standard for subsequent in vivo studies investigating the cartilage regeneration potential of different treatment modalities.

Plate-associated localized osteitis in mini-pig by biofilm-forming Methicillin-resistant Staphylococcus aureus (MRSA): establishment of a novel experimental model.

PURPOSE: The increasing number of implant-associated infections during trauma and orthopedic surgery caused by biofilm-forming Staphylococcus aureus in combination with an increasing resistance of conventional antibiotics requires new therapeutic strategies. One possibility could be testing for different therapeutic strategies with differently coated plates. Therefore, a clinically realistic model is required. The pig offers the best comparability to the human situation, thus it was chosen for this model. The present study characterizes a novel model of a standardized low-grade acute osteitis with bone defect in the femur in mini-pigs, which is stabilized by a titanium locking plate to enable further studies with various coatings. METHODS: A bone defect was performed on the femur of 7 Aachen mini-pigs and infected with Methicillin-resistant S. aureus (MRSA ATCC 33592). The defect zone was stabilized with a titanium plate. After 14 days, a plate change, wound debridement and lavage were performed. Finally, after 42 days, the animals were lavaged and debrided again, followed by euthanasia. The fracture healing was evaluated radiologically and histologically. RESULTS: A local osteitis with radiologically visible lysis of the bone could be established. The unchanged high Colony-forming Units (CFU) in lavage, the significant differences in Interleukin (IL)-6 in blood compared to lavage and the lack of increase in Alkaline Phosphates (ALP) in serum over the entire observation period show the constant local infection. CONCLUSION: The study shows the successful induction of local osteitis with lysis of the bone and the lack of enzymatic activity to mineralize the bone. Therefore, this standardized mini-pig model can be used in further clinical studies, to investigate various coated implants, bone healing, biofilm formation and immune response in implant-associated osteitis.

Differentiation among the most important Rodentibacter species by multiplex PCR assays targeting the ITSile+ala sequences of the rRNA operons.

Screening for the Rodentibacter species is part of the microbiologic quality assurance programs of laboratory rodents all over the world. Nevertheless, currently there are no PCR amplification techniques available for the diagnostic of R. ratti, R. heidelbergensis and of a Rodentibacter related ß-haemolytic taxon. The aim of this study was to utilize the differences in the sequence of the Internal Transcribed Spacer (ITS) regions of R. pneumotropicus, R. heylii, R. ratti, R. heidelbergensis and of the ß-haemolytic Rodentibacter taxon for the design of specific PCR assays for these species. The ITSile+ala sequence variations allowed the design of specific forward and reverse primers for each species included, that could be combined in different multiplex assays. The performance characteristics specificity and sensitivity registered for each primer pair against a diverse collection of Pasteurellaceae isolated from rats and mice and of further non-Pasteurellaceae strains was 100% for all five Rodentibacter species included. In addition, the PCR assays displayed high limits of detection and could be successfully used for detection of Rodentibacter spp. DNA in clinical swabs of laboratory mice and rats. Overall, the assays described here represent the first PCRs able to diagnose R. ratti, R. heidelbergensis and the ß-haemolytic Rodentibacter taxon, whose diagnostic to species level could further facilitate better understanding of their geographic distribution, prevalence, and biology in the future.

Influence of titanium implant surface characteristics on bone regeneration in dehiscence-type defects: an experimental study in dogs.

OBJECTIVES: The aim of the present study was to compare bone regeneration in dehiscence-type defects at titanium implants with chemically modified sandblasted/acid-etched (modSLA) or dual acid-etched surfaces with a calcium phosphate nanometre particle modification (DCD/CaP). MATERIALS AND METHODS: Buccal dehiscence-type defects were surgically created following implant site preparation in both the upper and the lower jaws of 12 fox hounds. Both types of implants were randomly allocated in a split-mouth design and left to heal in a submerged position for 2 and 8 weeks. Dissected blocks were processed for histomorphometrical analysis [e.g. new bone height (NBH), percentage of bone-to-implant contact (BIC), area of new bone fill (BF), and area of mineralized tissue (MT) within BF]. RESULTS: At 2 and 8 weeks, both groups revealed comparable mean BF (2.3+/-0.6 to 2.5+/-0.6 mm(2)versus 2.0+/-0.6 to 1.4+/-0.5 mm(2)) and MT (31.1+/-14.3-83.2+/-8.2%versus 38.9+/-15.9-84.4+/-6.3%) values. However, modSLA implants revealed significantly higher mean NBH (2.4+/-0.8 to 3.6+/-0.3 mm versus 0.9+/-0.8 to 1.8+/-1.4 mm) and BIC (53.3+/-11.3-79.5+/-6.6%versus 19.3+/-16.4-47.2+/-30.7%) values than DCD/CaP implants. CONCLUSION: ModSLA implants may have a higher potential to support osseointegration in dehiscence-type defects than DCD/CaP implants.

Impact of guided bone regeneration and defect dimension on wound healing at chemically modified hydrophilic titanium implant surfaces: an experimental study in dogs.

OBJECTIVES: The aim of the present study was to evaluate the impact of guided bone regeneration and defect dimension on wound healing at chemically modified titanium implant surfaces (modSLA). MATERIALS AND METHODS: ModSLA implants were placed at chronic-type lateral ridge defects of different heights (H1-H4: 2, 4, 6 and 8 mm) and randomly allocated to either (a) GBR (polyethylene glycol membrane + biphasic calcium phosphate) or (b) untreated control. At 2 and 8 weeks (n=6 dogs each), dissected blocks were processed for histomorphometrical analysis [e.g., percentage linear fill (PLF), regenerated area (RA)]. RESULTS: At 8 weeks, both groups revealed comparable mean PLF (%) [ CONTROL: H1 (26.1 +/- 5.8)-H4 (60.4 +/- 11.8); GBR: H1 (8.3 +/- 5.3)-H4 (50.7 +/- 23.1)] and RA (mm(2)) [ CONTROL: H1 (2.5 +/- 0.4)-H4 (7.4 +/- 4.1); GBR: H1 (1.8 +/- 1.0)-H4 (10.8 +/- 5.9)] values. A significant difference was observed for the mean PLF values at H1 defects. CONCLUSION: It was concluded that (i) modSLA titanium implants supported bone regeneration and osseointegration at H1-H4 defects and (ii) the present GBR procedure did not seem to improve the outcome of vertical bone regeneration, but tended to increase the mean RA values.

Lateral ridge augmentation using equine- and bovine-derived cancellous bone blocks: a feasibility study in dogs.

OBJECTIVES: The aim of the present study was to histologically evaluate and compare a new prototype collagen type I/III-containing equine- (EB) and a bovine- (BB) derived cancellous bone block in a dog model. MATERIALS AND METHODS: Four standardized box-shaped defects were bilaterally created at the buccal aspect of the alveolar ridge in the lower jaws of five beagle dogs and randomly allocated to either EB or BB. Each experimental site was covered by a native (non-crosslinked) collagen membrane and left to heal in a submerged position for 12 weeks. Dissected blocks were processed for semi-/and quantitative analyses. RESULTS: Both groups had no adverse clinical or histopathological events (i.e. inflammatory/foreign body reactions). BB specimens revealed no signs of biodegradation and were commonly embedded in a fibrous connective tissue. New bone formation and bony graft integration were minimal. In contrast, EB specimens were characterized by a significantly increased cell (i.e. osteoclasts and multinucleated giant cells)-mediated degradation of the graft material (P<0.001). The amount and extent of bone ingrowth was consistently higher in all EB specimens, but failed to reach statistical significance in comparison with the BB group (P>0.05). CONCLUSIONS: It was concluded that the application of EB may not be associated with an improved bone formation than BB.