Long-term bony integration and resorption kinetics of a xenogeneic bone substitute after sinus floor augmentation: histomorphometric analyses of human biopsy specimens.

In this case series, a systematic histomorphometric analysis of two human bone biopsy specimens was conducted 1 and 5 years after grafting with a xenogeneic bovine bone substitute material (BSM). While the 1-year specimen still showed extensive signs of an active desmal ossification, the specimen after 5 years mainly showed mature lamellar bone without bone turnover or remodeling. A completed bony integration without extensive resorption of the BSM particles could be detected. Altogether, a good integration in the bone with osteoconduction and a high biocompatibility was seen.

Depth profile analysis of non-specific fluorescence and color of tooth tissues after peroxide bleaching.

PURPOSE: To examine laboratory changes of endogenous non-specific fluorescence and color throughout subsurface of tooth structures prior to and following peroxide bleaching. METHODS: Extracted human teeth were cross sectioned and mounted on glass slides. Cross sections were examined for internal color (digital camera) and nonspecific fluorescence (microRaman spectroscopy) throughout the tooth structure at specified locations. Surfaces of sections were then saturation bleached for 70 hours with a gel containing 6% hydrogen peroxide. Cross sections were reexamined for color and non-specific fluorescence changes. RESULTS: Unbleached enamel, dentin-enamel junction and dentin exhibit different CIELab color and non-specific fluorescence properties. Bleaching of teeth produced significant changes in color of internal cross sections and substantial reductions of non-specific fluorescence levels within enamel dentin and DEJ. Enamel and dentin non-specific fluorescence were reduced to common values with bleaching with enamel and the DEJ showing larger reductions than dentin.

Early root surface colonization by human periodontal ligament fibroblasts following treatment with different biomaterials.

OBJECTIVES: The present in-vitro study examined the effects of different biomaterials on early root surface colonization by human periodontal ligament (PDL) fibroblasts using confocal-laser-scanning-microscopy (CLSM). MATERIALS AND METHODS: Fifteen periodontally-diseased teeth were extracted, treated with scaling/root planing and longitudinally cut to obtain 30 root fragments. Fragments were treated either with 24% EDTA following application of enamel matrix derivative (EMD), 24% EDTA or EMD only, nanocrystalline hydroxyapatite (NHA) paste or oily calcium hydroxide suspension (OCHS) for 1 h each. The analogue untreated root specimens served as controls. Root fragments were incubated with human PDL fibroblasts and cellular proliferation and morphology were evaluated after 1, 3, 5 and 8 days using CLSM-visualization and image recognition software. RESULTS: The rate of cellular proliferation was different among treatment modalities examined (p = 0.019). Except treatment with NHA paste all treatment modalities improved cellular proliferation on root surfaces at all different points of time compared with the control specimens. A significant difference between treatment modalities was observed between EMD and NHA paste (p = 0.008). No synergistic effect could be demonstrated comparing root surface conditioning with 24% EDTA and EMD application compared to 24% EDTA or EMD application only. CONCLUSION: The present results suggest that initial root surface colonization by PDL fibroblasts may be enhanced by root surface conditioning with 24% EDTA and application of EMD, application of 24% EDTA or EMD alone and OCHS. The addition of 24% EDTA for root surface conditioning prior to EMD application provided no synergistic effects in terms of early root surface colonization by PDL fibroblasts.

Multi-photon imaging of amine-functionalized silica nanoparticles.

A convenient and simple strategy for preparing water soluble, photoluminescent functionalized silica nanoparticles (M-dots) in the absence of fluorophores or metal doping is demonstrated. These M-dots can be used for bioimaging using one and two-photon microscopy. Because of their high photostability, low toxicity and high biocompatibility compared with Lumidot™ CdSe/ZnS quantum dots, functionalized silica particles are superior alternatives for current bioimaging platforms. Moreover, the presence of a free amine group at the surface of the M-dots allows biomolecule conjugation (e.g. with antibodies, proteins) in a single step for converting these photoluminescent SiO(2) nanoparticles into multifunctional efficient vehicles for theragnostics.

Comparative analysis of numerical and experimental data of orthodontic mini-implants.

The purpose of this study was to compare numerical simulation data derived from finite element analysis (FEA) to experimental data on mini-implant loading. Nine finite element (FE) models of mini-implants and surrounding bone were derived from corresponding experimental specimens. The animal bone in the experiment consisted of bovine rib. The experimental groups were based on implant type, length, diameter, and angle of insertion. One experimental specimen was randomly selected from each group and was digitized in a microCT scanner. The FE models consisted of bone pieces containing Aarhus mini-implants with dimensions 1.5 × 7 mm and 1.5 × 9 mm or LOMAS mini-implants (dimensions 1.5 × 7 mm, 1.5 × 9 mm, and 2 × 7 mm). Mini-implants were inserted in two different ways, perpendicular to the bone surface or at 45 degrees to the direction of the applied load. Loading and boundary conditions in the FE models were adjusted to match the experimental situation, with the force applied on the neck of the mini-implants, along the mesio-distal direction up to a maximum of 0.5 N. Displacement and rotation of mini-implants after force application calculated by FEA were compared to previously recorded experimental deflections of the same mini-implants. Analysis of data with the Altman-Bland test and the Youden plot demonstrated good agreement between numerical and experimental findings (P = not significant) for the models selected. This study provides further evidence of the appropriateness of the FEA as an investigational tool in relevant research.

Circumferential spicule growth by pericellular silica deposition in the hexactinellid sponge Monorhaphis chuni.

The giant basal spicule of the hexactinellid sponge Monorhaphis chuni represents the longest natural siliceous structure on Earth. This spicule is composed of concentrically arranged lamellae that are approximately 10 µm thick. In the present study, we investigated the formation of outer lamellae on a cellular level using microscopic and spectroscopic techniques. It is shown that the formation of an outermost lamella begins with the association of cell clusters with the surface of the thickening and/or growing spicule. The cells release silica for controlled formation of a lamella. The pericellular (silica) material fuses to a delimited and textured layer of silica with depressions approximately 20-30 µm in diameter. The newly formed layer initially displays 40 µm wide, well-structured banded ribbons and only attains its plain surface in a final step. The chemical composition in the depressions was studied using energy dispersive X-ray spectroscopy and by staining with Texas Red. The data suggest that those depressions are the nests for the silica-forming cells and that silica formation starts with a direct association of silica-forming cells with the outer surface of the spicule, where they remain and initiate the development of the next lamellae.

Three-dimensional analysis of bone formation after maxillary sinus augmentation by means of microcomputed tomography: a pilot study.

PURPOSE: Although many studies have analyzed the suitability of different grafting materials for maxillary sinus augmentation by means of histomorphometry in conventional histologic strains, the three-dimensional (3D) structure and remodeling of these grafts after healing beneath the sinus membrane remain unclear. The aim of the present study was to determine whether microcomputed tomography is a suitable method to evaluate the 3D structure and remodeling of grafts after sinus floor augmentation. MATERIALS AND METHODS: Sinus floor augmentation was performed in five patients using autogenous bone (AB) alone, AB and beta-tricalcium phosphate (b-TCP, Cerasorb), AB and b TCP/hydroxyapatite (HA) (BoneCeramic), AB and calcium carbonate (Algipore), and AB and HA (PepGen). Specimens from the grafted sites were harvested by means of a trephine bur 5 to 16 months after maxillary sinus augmentation. Microcomputed tomography of these specimens was performed with a nominal isotropic resolution of 6 x 6 x 6 µm² voxel size. After segmentation, 3D images were reconstructed, and the distribution of bone and substitute material was evaluated by means of volumetric and density measurements. RESULTS: In all images, both bone and substitute material could clearly be identified. The connectivity of trabeculae surrounding the substitute material was visible in the 3D reconstructions. Volumetric evaluation such as total bone volume, volume of substitute material, and trabecular thickness and spacing revealed differences between the different grafting materials. CONCLUSION: Microcomputed tomography is a promising method to evaluate the 3D structure of grafts after sinus floor augmentation with autogenous bone and bone substitute materials.

Long-term response of osteogenic cells on micron and submicron-scale-structured hydrophilic titanium surfaces: sequence of cell proliferation and cell differentiation.

OBJECTIVE: Modifications of surface topography and surface chemistry are key factors for guiding target cells during dental implant healing. Recent in vitro studies confirmed promotion of early osteogenic cell differentiation on submicron scaled surfaces in particular when hydrophilized. However, no long-term observations on both osteogenic cell proliferation as well as on cell maturation have been reported for respectively modified surfaces. Aim of this study was to monitor osteogenic cell proliferation and expression of specific osteogenic cell differentiation markers on a protein level over an extended period of 3 weeks with respect to surface modifications. MATERIAL AND METHODS: Modified titanium (Ti) disks were obtained from Institute Straumann, representing the following surfaces: smooth pretreatment (PT), sandblasted/acid etched (SLA), and hydrophilized (modSLA). Surface topography was analyzed by scanning electron microscopy, surface elemental composition was assessed by X-Ray Photoelectronic Spectroscopy (XPS). Tissue culture polystyrene (TCPS) served as a control substrate. Human osteogenic cells (HOB-c) were cultivated on the respective substrates. After 24 hrs, 48 hrs, 72 hrs, 7 d, 14 d and 21 d, cell count was assessed as well as osteogenic cell differentiation utilizing cellular Quantitative Immuno-Cytochemistry (QIC) assay for collagen type I (COL), alkaline phosphatase (AP), osteopontin (OPN) and osteocalcin (OC). Data were normalized with respect to internal controls. RESULTS: In contrast to the other modified Ti disks, modSLA stands out due to low surface carbon contamination. TCPS and PT surfaces preserved a rather immature, mitotic active osteogenic phenotype (high proliferation rates, no increase of OC production), SLA and especially modSLA surfaces promoted the maturation of osteogenic precursors into post-mitotic osteoblasts. In detail, modSLA resulted in lowest cell proliferation rates, but exhibited highest expression rates of OC. DISCUSSION: Our results, which confirm previous studies, reveal long-term promotion of osteogenic cell maturation by topography (micron and submicron scale roughness) and surface hydrophilicity.

Pore characteristics of bone substitute materials assessed by microcomputed tomography.

OBJECTIVES: Pore configurations of alloplastic biomaterial scaffolds play a major role for new bone formation in vivo. Current studies on characteristics of pores in bone substitute materials focus on individual particles or single blocks. Thus, three-dimensional (3-D) architecture of particle aggregates, representing the clinical relevant in vivo situation is not adequately taken into account. The aim of this study was the visualization and quantification of pore properties, both of the scaffold structure of single particles as well as of the micro-morphology of complex 3-D aggregated particle-conglomerates. MATERIAL AND METHODS: In model experiments, standardized plexiglass cylinders were stuffed with commercial bone substitute material particles with diverse chemical composition (HA, beta-TCP, HA-SiO(2), HA-beta-TCP, bioactive glass), origin (phycogenic, bovine, synthetic) and granulation (50 mum-2000 mum). Analogue to establish procedures for native (human) bone samples, non-fixed bone substitute materials were scanned by high-resolution microcomputed tomography. In addition to computer animated two-dimensional and 3-D reconstruction of the samples, median pore thickness and pore size distribution were determined. Materials representative for their chemical constitution were documented by SEM imaging. RESULTS: Investigated specimens significantly were different in micro-morophology and pore properties, ranging from highly porous to rather solid. The most voluminous pores were localized interparticularly. Within one product line, the determined pore properties showed a significant correlation with single particle grain sizes. CONCLUSION: The generation and interpretation of micro-CT based 3-D pore models can provide further insight into the expected osteoconduction dynamics and therefore might serve as a basis for further modifications of scaffold size and geometry as well as for further invasive studies on the biological behaviour of the scaffolds.

Axial growth of hexactinellid spicules: formation of cone-like structural units in the giant basal spicules of the hexactinellid Monorhaphis.

The glass sponge Monorhaphis chuni (Porifera: Hexactinellida) forms the largest bio-silica structures on Earth; their giant basal spicules reach sizes of up to 3m and diameters of 8.5mm. Previously, it had been shown that the thickness growth proceeds by appositional layering of individual lamellae; however, the mechanism for the longitudinal growth remained unstudied. Now we show, that the surface of the spicules have towards the tip serrated relief structures that are consistent in size and form with the protrusions on the surface of the spicules. These protrusions fit into the collagen net that surrounds the spicules. The widths of the individual lamellae do not show a pronounced size tendency. The apical elongation of the spicule proceeds by piling up cone-like structural units formed from silica. As a support of the assumption that in the extracellular space silicatein(-like) molecules exist that associate with the external surface of the respective spicule immunogold electron microscopic analyses were performed. With the primmorph system from Suberites domuncula we show that silicatein(-like) molecules assemble as string- and net-like arrangements around the spicules. At their tips the silicatein(-like) molecules are initially stacked and at a later stay also organized into net-like structures. Silicatein(-like) molecules have been extracted from the giant basal spicule of Monorhaphis. Applying the SDS-PAGE technique it could be shown that silicatein molecules associate to dimers and trimers. Higher complexes (filaments) are formed from silicatein(-like) molecules, as can be visualized by electron microscopy (SEM). In the presence of ortho-silicate these filaments become covered with 30-60nm long small rod-like/cuboid particles of silica. From these data we conclude that the apical elongation of the spicules of Monorhaphis proceeds by piling up cone-like silica structural units, whose synthesis is mediated by silicatein(-like) molecules.

The effects of high concentration tooth whitening bleaches on microleakage of Class V composite restorations.

OBJECTIVE: To explore the effects of high-concentration hydrogen peroxide bleaching agents on the microleakage of composite restorations. METHODS: In 60 extracted human molars, Class V restorations were prepared with Scotchbond 1/Filtek Z250 composite. Teeth were randomly divided into four groups: (1) no bleaching; (2) bleaching with 14% hydrogen peroxide gel from Crest Whitestrips; (3) bleaching with 20% carbamide peroxide gel from Opalescence PF 20; and (4) bleaching with 38% hydrogen peroxide gel Opalescence Xtra Boost. Bleaching procedures were carried out at 37 degrees C for 21 days/42 hours (2); seven days/42 hours (3); one day/45 minutes (4). Varnish was applied on the apical portion of the teeth only, excluding the restoration, prior to immersion in a 0.1% rhodamin-B-isothiocyanate solution for 24 hours at 37 degrees C. After rinsing, specimens were embedded in methacrylate blocks, and sectioned with a water-cooled microtome with three restoration cuts positioned centrally parallel to the long axis of the tooth. Microleakage was evaluated at the occlusal margins of the Class V restorations using a stereo microscope, separate for dentin and enamel margins. RESULTS: Over 90% of enamel margins exhibited no microleakage following cycling. Bleaching agents had almost no effect on numerical averages. Eighty-eight percent of the dentin margins were free of microleakage for the non-treated control group. Bleaching treatments collectively had slight numerical reductions to around 80%. The statistical evaluation (Kruskal-Wallis-test) showed no significant difference in microleakage between groups for enamel or dentin. CONCLUSION: Bleaching with the materials tested had no influence on microleakage of Filtek Z250 composite bonded with Scotchbond 1.

Effect of bleaching treatments on microleakage of Class I restorations.

OBJECTIVE: To test the effect of bleaching agents on microleakage of composite restorations. METHODS: Sixty extracted human molar class I cavities were restored using Scotchbond 1 and Filtek Z250 composite according to the manufacturer's instructions. The teeth were randomly divided into four groups (n = 15 each). Group 1 was the control group, which was not bleached. Group 2 had a once-daily bleaching treatment with 20% carbamide peroxide gel for eight hours. Group 3 had a bleaching of 6% H2O2 for 30 minutes twice a day. Group 4 had a bleaching treatment once per day with 19% percarbonate gel for eight hours. The bleaching was carried out at 37 degrees C for 14 days. Nail varnish was applied on the apical portion of the teeth only, and the specimens were immersed in a 0.1% rhodamin-B-isothiocyanate for 24 hours at 37 degrees C. After thorough rinsing with tap water, the specimens were embedded in self-curing methacrylate resin. The blocks were sectioned with a water-cooled microtome saw into three to five slices. The cuts were positioned centrally through the restorations and approximately parallel to the long axis of the tooth in the mesiodistal direction. Microleakage was evaluated at the occlusal margins of the class I restorations using a stereo microscope. RESULTS: Microleakage occurred in all groups. The percentage of sections showing leakage was 20% (Group 1), 11% (Group 2), 15% (Group 3), and 18% (Group 4). The statistical evaluation (Kruskal-Wallis test) showed no significant difference between groups (p = 0.537). CONCLUSION: Bleaching with the materials tested has no influence on microleakage of Filtek composite bonded with Scotchbond I.

Effects of hydrogen peroxide bleaching strips on root surfaces in vitro.

OBJECTIVE: This study examined the effects of hydrogen peroxide tooth whiteners on the physical hardness and morphology of human root dentin cycled through bleaching treatments in vitro. METHODOLOGY: Human root dentin was ground and polished to prepare a uniform substrate for bleaching treatments. Half the root dentin specimens were acid (EDTA) etched to remove the smear layer, while the other half were treated with an intact smear layer. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included Crest Whitestrips bleaching gels, which utilize hydrogen peroxide as the in situ bleaching source at 5.3 and 6.5% concentrations of hydrogen peroxide, placebo gels containing no hydrogen peroxide, and an untreated control group. Surface color measurements were taken prior to and following bleaching. Effects of bleach on physical properties of dentin were assessed with microhardness, and surface morphology effects were studied with scanning electron microscopy (SEM). RESULTS: Color assessments confirmed significant ex vivo tooth bleaching by treatments. Surface microhardness values remained the same or increased slightly with bleaching treatments for both smear layer and etched dentin surfaces. SEM measures of non-etched dentin surfaces cycled with bleach showed preservation of the dentin smear layer. SEM of etched dentin treated with bleach showed maintenance of standard tubule diameters. CONCLUSION: These results confirm that tooth bleaching with hydrogen peroxide bleaching gels at 5.3 and 6.5% concentrations do not produce solubilization reactions on dentin surfaces in vitro, and that dentin smear layers remain intact following bleaching exposures.

Stannous fluoride/sodium hexametaphosphate dentifrice increases dentin resistance to tubule exposure in vitro.

OBJECTIVE: The purpose of this study was to compare the reactivity of three dentifrice formulations on smear layer-covered root dentin surfaces, and the effects of the formulation treatments on resistance to acid softening and dentinal tubuli disclosure. METHODOLOGY: Commercial dentifrices, including Crest Cavity Protection Regular, Colgate Total, and a new dentifrice comprised of stannous fluoride/sodium hexametaphosphate (SnF2/HMP: Crest Pro-Health), were cycled through a pre-treatment period on smear layer-covered dentin surfaces, including intermittent soaking in dentifrice slurries and whole human saliva immersion. Following pre-treatments, the cycling treatments were modified to include dietary acid exposure, including soaks in an acidic soft drink. Vickers surface microhardness, variable pressure scanning electron microscopy (VP-SEM), and confocal laser scanning microscopy in reflection mode (CLSM) were used to characterize dentin reactivity and smear layer protection. RESULTS: CLSM and SEM analyses showed that specimens treated with SnF2/HMP appeared to resist acid solubilization, evidenced by the absence of disclosed dentinal tubuli. The histo-tomographic observations in this study were in agreement with the hardness measurements. The superior surface protection of dentin with SnF2/HMP would suggest potential benefits in ameliorating dentinal hypersensitivity in the clinical situation. CONCLUSION: A stannous fluoride/sodium hexametaphosphate dentifrice prevents dietary acid softening and tubule exposure of smear layer dentin surfaces.

Effects of elevated hydrogen peroxide 'strip' bleaching on surface and subsurface enamel including subsurface histomorphology, micro-chemical composition and fluorescence changes.

OBJECTIVES: This study examined the effects of elevated concentration hydrogen peroxide tooth whitening treatments on tooth surface and subsurface integrity. METHODS: Sound human molars were ground and polished to prepare an uniform substrate for bleaching treatments. A cycling treatment included alternating ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching was carried out with prototype bleaching strips containing hydrogen peroxide gel at 13% and 16% concentrations. A non-bleached group was used as a control. Treatments included 28h of total bleaching exposure in vitro. Surface color was measured prior to and following bleaching. Effects of bleach on physical properties of tooth surfaces were assessed by microhardness measures on enamel. Ultrastructural effects were examined by surface and subsurface confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. In addition, the effects of bleaching on tooth micro-chemical composition were studied by Raman spectroscopy combined with CLSM technique. RESULTS: Color assessments confirmed significant ex vivo tooth bleaching. Surface microhardness and VP-SEM (variable pressure SEM) measures revealed no deleterious effects on the enamel surfaces. CLSM micromorphological assessments supported the safety of hydrogen peroxide bleaching strips both on surface and subsurface enamel, DEJ and dentin ultrastructure. Raman spectroscopy analysis demonstrated no obvious effects of bleaching treatments on the micro-chemical composition of enamel and dentin. Significant effects of bleaching were seen in reducing background luminescence of Raman spectra obtained from enamel and dentin. CONCLUSIONS: These results confirm that hydrogen peroxide whitening strips do not produce changes in surface/subsurface histomorphology, surface microhardness and micro-chemical composition of teeth. Effects of bleaches on tooth luminescence recorded in micro-Raman spectroscopy may serve as an internal signature to bleaching effects and warrant further study.

Physical, morphological, and micro-Raman chemical studies on bleaching strip effects on enamel, coronal dentin, and root dentin.

OBJECTIVE: This study examined the effects of elevated-concentration hydrogen peroxide tooth whitening strips on the surface and subsurface integrity of enamel, coronal dentin, and root dentin. METHODOLOGY: Sound human teeth were ground and polished to prepare a uniform substrate for bleaching. A cycling regimen included exposures to saliva, bleaching treatments, and fluoridated toothpaste. Bleaching was carried out with plastic strips containing hydrogen peroxide gel at 11.7 and 14% concentrations. A non-bleached group served as a control. Bleaching times measured up to 45 hours. Physical properties of tooth surfaces were assessed by microhardness, while surface morphological properties of teeth were examined by profilometry, surface Confocal Laser Scanning Microscopy (CLSM), and Variable Pressure Scanning Electron Microscopy (VP-SEM). Subsurface histomorphological effects on teeth were assessed by CLSM. Lastly, the influences of bleaching on tooth micro-chemical composition was studied by micro-Raman spectroscopy using a unique spectrometer in line, coupled to the CLSM via glass fiber. RESULTS: Surface microhardness, profilometry, CLSM, and VP-SEM measures showed enamel and root dentin surfaces were unchanged with bleaching. CLSM micromorphological assessments demonstrated normal histology for bleached teeth on surface and subsurface enamel, DEJ, and dentin. Raman spectroscopy demonstrated no effects of bleaching treatments on the microchemical mineral composition of enamel and dentin. Bleaching treatments were observed to reduce background luminescence of enamel, DEJ, and dentin. CONCLUSION: These results confirm that whitening strips delivering controlled doses of hydrogen peroxide at 11.7 and 14% concentrations do not produce changes in surface/subsurface histomorphology, surface microhardness, or micro-chemical mineral composition of teeth. The effects of bleaches on tooth luminescence recorded in micro-Raman spectroscopy may serve as an internal signature to bleaching effects and warrant further study.

Effects of hydrogen peroxide bleaching strips on tooth surface color, surface microhardness, surface and subsurface ultrastructure, and microchemical (Raman spectroscopic) composition.

OBJECTIVE: This study examined the effects of hydrogen peroxide tooth bleaching strips on the surface hardness and morphology of enamel and the ultrastructure and chemical composition of enamel and dentin in vitro. METHODOLOGY: Sound human molars were ground and polished to prepare a uniform substrate for bleaching treatments. A cycling treatment methodology was employed which alternated ex vivo human salivary exposures with bleaching treatments under conditions of controlled temperature and durations of treatment. Bleaching treatments included commercial Crest Whitestrips bleaching strips, which utilize hydrogen peroxide in a gel as the in situ bleaching source at 6.0 and 6.5% concentrations of H2O2. Control treatments included an untreated group. Crest Whitestrips bleaching included treatment exposures simulating 2x the recommended clinical exposures (28 hours bleaching). Surface color measurements were taken prior to and following bleaching to ensure tooth bleaching activity. The effects of bleach on physical properties of enamel were assessed with microhardness measures. Ultrastructural effects were classified by surface and subsurface confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) techniques. In addition, the effects of bleaching on tooth microchemical composition was studied in different tooth regions by coincident assessment of Raman spectroscopic signature. RESULTS: Color assessments confirmed significant ex vivo tooth bleaching by Whitestrips. Surface microhardness and SEM measures revealed no deleterious effects on the enamel surfaces. CLSM micromorphological assessments supported the safety of hydrogen peroxide bleaching strips both on surface and subsurface enamel, DEJ, and dentin ultrastructure. Raman spectroscopy analysis demonstrated no obvious effects of bleaching treatments on the microchemical composition of enamel and dentin. CONCLUSION: These results confirm that tooth bleaching with hydrogen peroxide whitening strips does not produce changes in surface/subsurface histomorphology or in surface microhardness and ultrastructure of treated teeth. In addition, for the first time, these results confirm the safety of hydrogen peroxide bleaching strips to tooth microchemical composition as measured by Raman spectroscopy.

Increased polyethylene wear after cementless ABG I total hip arthroplasty.

INTRODUCTION: The cementless, hydroxyapatite-coated Anatomique Benoist Giraud-I (ABG-I) hip endoprosthesis represented a modern implant in the 1990s. The aim of the current retrospective study was to evaluate the clinical and radiological results of this prosthesis. In addition, an analysis of the complications and retrieved implants was conducted. MATERIALS/METHODS: The medium-term results (follow-up 5.23 years) of 193 hip joints are presented. Of 158 total cohorts, 81.9% was able to undergo follow-up performed with standardized clinical and radiological investigations. Physical characteristics of the patients and the underlying disease prompting the need for total hip arthroplasty, as well as a clinical score (Merle d'Aubigné) were recorded. At the time of follow-up, a radiologic examination of all patients with a standardized evaluation was performed. In addition, the migration of the acetabular cup and femoral head as well as polyethylene wear could be determined digitally in 118 cases (61.1%) using one-picture Roentgen analysis. RESULTS: Clinical results, as measured with a Merle d'Aubigné Score increase from 8.4 to 16.2, were very good. Radiographs demonstrated successful osseous integration of the anatomically molded shaft. Within the period of the investigation, no revision procedures of the femoral shaft were necessary. However, the rate of polyethylene abrasion of 0.23 mm/year was markedly high. 13.9% of hips (n = 27) required acetabular cup revision due to wear. This calculates to a prosthesis 7-year survival probability of 63%. Intraoperative findings during the revision cases showed extensive periacetabular osteolysis with foreign body granulation tissue. Analysis of data from the total patient cohort versus data from cases requiring revision showed a significantly increased frequency of high polyethylene wear in young active patients as well as in cases where an unfavorable acetabular cup to femoral head relation existed in correspondence with polyethylene thickness. There is evidence, however, that suggests that multifactorial causes for the increased wear are significant in regards to the principal material and technical features of the prosthesis. CONCLUSION: On the basis of these results, it is strongly recommended that all patients treated with an ABG-I hip endoprosthesis should receive close clinical and most importantly close radiologic follow-up.

In vitro evaluation of the biocompatibility of contaminated implant surfaces treated with an Er : YAG laser and an air powder system.

Titanium platelets with a sand-blasted and acid-etched surface were coated with bovine serum albumin and incubated with a suspension of Porphyromonas gingivalis (ATCC 33277). Four groups with a total of 48 specimens were formed. Laser irradiation of the specimens (n = 12) was performed on a computer-controlled XY translation stage at pulse energy 60 mJ and frequency 10 pps. Twelve specimens were treated with an air powder system. After the respective treatment, human gingival fibroblasts were incubated on the specimens. The proliferation rate was determined by means of fluorescence activity of a redox indicator (Alamar Blue Assay) which is reduced by metabolic activity related to cellular growth. Proliferation was determined up to 72 h. Contaminated and non-treated as well as sterile specimens served as positive and negative controls. Proliferation activity was significantly (Mann-Whitney U-test, P < 0.05) reduced on contaminated and non-treated platelets when compared to sterile specimens. Both on laser as well as air powder-treated specimens, cell growth was not significantly different from that on sterile specimens. Air powder treatment led to microscopically visible alterations of the implant surface whereas laser-treated surfaces remained unchanged. Both air powder and Er : YAG laser irradiation have a good potential to remove cytotoxic bacterial components from implant surfaces. At the irradiation parameters investigated, the Er : YAG laser ensures a reliable decontamination of implants in vitro without altering surface morphology.

Effects of Crest Whitestrips bleaching on subsurface microhardness and ultrastructure of tooth enamel and coronal dentin.

PURPOSE: To describe the complementary subsurface analysis of structural and ultrastructural effects of bleaching with Crest Whitestrips on enamel and coronal dentin METHODS: Human tooth enamel specimens were cycled through a daily regimen including salivary immersions and treatments with commercial tooth whitening gels containing hydrogen peroxide or carbamide peroxide. Treatments with hydrogen peroxide in Crest Whitestrips gel base were carried out for up to 70 hours bleaching (some five fold to the clinical exposure required to produce satisfactory whitening in bleaching strip systems as established by double blind placebo controlled clinical studies) [correction]. Following in vitro laboratory cycling, the teeth were cross sectioned and remounted for observation of microhardness and ultrastructural characteristics in subsurface regions. Ultrastructure was assessed by application of confocal laser scanning microscopy (reflection mode). RESULTS: Peroxide whitening compositions had no effects on subsurface microhardness of enamel or dentin, even under conditions of five fold overbleaching. Crest Whitestrips gel containing up to 6.5% hydrogen peroxide applied for periods up to 70 hours (five kit) overbleaching was found to produce no changes (at a lateral resolution of 200-300 nm) in observed subsurface enamel and dentin ultrastructure or architecture.