Evaluation of three-dimensional biofilms on antibacterial bonding agents containing novel quaternary ammonium methacrylates

Antibacterial adhesives are promising to inhibit biofilms and secondary caries. The objectives of this study were to synthesize and incorporate quaternary ammonium methacrylates into adhesives, and investigate the alkyl chain length effects on three-dimensional biofilms adherent on adhesives for the first time. Six quaternary ammonium methacrylates with chain lengths of 3, 6, 9, 12, 16 and 18 were synthesized and incorporated into Scotchbond Multi-Purpose. Streptococcus mutans bacteria were cultured on resin to form biofilms. Confocal laser scanning microscopy was used to measure biofilm thickness, live/dead volumes and live-bacteria percentage vs. distance from resin surface. Biofilm thickness was the greatest for Scotchbond control; it decreased with increasing chain length, reaching a minimum at chain length 16. Live-biofilm volume had a similar trend. Dead-biofilm volume increased with increasing chain length. The adhesive with chain length 9 had 37% live bacteria near resin surface, but close to 100% live bacteria in the biofilm top section. For chain length 16, there were nearly 0% live bacteria throughout the three-dimensional biofilm. In conclusion, strong antibacterial activity was achieved by adding quaternary ammonium into adhesive, with biofilm thickness and live-biofilm volume decreasing as chain length was increased from 3 to 16. Antibacterial adhesives typically only inhibited bacteria close to its surface; however, adhesive with chain length 16 had mostly dead bacteria in the entire three-dimensional biofilm. Antibacterial adhesive with chain length 16 is promising to inhibit biofilms at the margins and combat secondary caries.     

Anti-proteolytic capacity and bonding durability of proanthocyanidin-biomodified demineralized dentin matrix

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin（PA） for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin–dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.     

The Role of Host-derived Dentinal Matrix Metalloproteinases in Reducing Dentin Bonding of Resin Adhesives

Dentin matrix metalloproteinases （MMPs） are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength.
Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhe- sives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.     

A novel protein-repellent dental composite containing 2-methacryloyloxyethyl phosphorylcholine

Secondary caries due to biofilm acids is a primary cause of dental composite restoration failure.To date,there have been no reports of dental composites that can repel protein adsorption and inhibit bacteria attachment.The objectives of this study were to develop a protein-repellent dental composite by incorporating 2-methacryloyloxyethyl phosphorylcholine(MPC) and to investigate for the first time the effects of MPC mass fraction on protein adsorption,bacteria attachment,biofilm growth,and mechanical properties.Composites were synthesized with 0(control),0.75%,1.5%,2.25%,3%,4.5%and 6%of MPC by mass.A commercial composite was also tested as a control.Mechanical properties were measured in three-point flexure.Protein adsorption onto the composite was determined by the microbicinchoninic acid method.A human saliva microcosm biofilm model was used.Early attachment at 4 h,biofilm at 2 days,live/dead staining and colony-forming units(CFUs) of biofilms grown on the composites were investigated.Composites with MPC of up to 3%had mechanical properties similar to those without MPC and those of the commercial control,whereas 4.5%and 6%MPC decreased the mechanical properties(P<0.05).Increasing MPC from 0 to 3%reduced the protein adsorption on composites(P<0.05).The composite with 3%MPC had protein adsorption that was 1/12 that of the control(P<0.05).Oral bacteria early attachment and biofilm growth were also greatly reduced on the composite with 3%MPC,compared to the control(P<0.05).In conclusion,incorporation of MPC into composites at 3%greatly reduced protein adsorption,bacteria attachment and biofilm CFUs,without compromising mechanical properties.Protein-repellent composites could help to repel bacteria attachment and plaque build-up to reduce secondary caries.The protein-repellent method might be applicable to other dental materials.     

Influence of fiber posts on the fracture resistance of endodontically treated premolars with different dental defects

This study aimed to evaluate the influence of quartz fiber post placement on the fracture resistance of endodontically treated premolars with different dental defects under dynamic loading.Fifty extracted single-rooted mandibular premolars were randomized into five groups.Each group was prepared according to numbers of residual walls ranged from 0 to 4.Then each group was divided into two subgroups with one restored with quartz fiber posts and the other without posts.In no-post groups,gutta percha point 2 mm below cemento-enamel junction was removed.Composite resin was adapted to the well and used to shape the core directly.Each tooth was restored with a complete metal crown.Dynamic loading was carried out in a masticatory simulator with a nominal load of 50 N at 2 Hz for 300 000 loading cycles.Then a quasi-statically load was applied in a universal testing machine 306 to the long axis with a crosshead speed of 1 mm？min21until fracture.Data were analyzed with one-way analysis of variance and pairwise comparison（P,0.05）.No specimens failed during dynamic loading.The fracture resistance enhanced with the increase of numbers of coronal walls and the differences were significant（P,0.05）.Placement of fiber posts had a significant effect when fewer than two walls remained（P,0.05）,but it had no significant influence in groups with two,three or four walls（P.0.05）.Fiber post did not change failure mode,and the fracture pattern was mainly favorable.More dentin walls need to be retained in clinic.When no less than two walls remained,a fiber post is not always necessary.     

Antimicrobial activity of alexidine alone and associated with N-acetylcysteine against Enterococcus faecalis biofilm

The purpose of this study was to assess the efficacy of alexidine（ALX）,alone and combined with N-acetylcysteine（NAC）,in eradicating two Enterococcus faecalis strain biofilms.The biofilms of E.faecalis ATCC 29212 and the clinical isolate E.faecalis D1 were grown in the MBEC-high-throughput device for 24 h and were exposed to five twofold dilutions of ALX（2%–0.007 8%）alone and combined with100 mg？mL21NAC,for 1 and 5 min.Eradication was defined as 100%kill of biofilm bacteria.The Student’s t-test was used to compare the efficacy of the associations of the two irrigants.After 1-min contact time,ALX eradicated the biofilms at all concentrations except for 0.007 8%and 0.015 6%–0.007 8%with E.faecalis ATCC 29212 and E.faecalis D1,respectively.Similar results for eradication and concentration were obtained when it was combined with 100 mg？mL21NAC.After 5 min of contact time,ALX alone and combined with NAC eradicated all enterococci biofilms.ALX showed antimicrobial properties against the two E.faecalis strain biofilms tested at very low concentrations,and its combined use with NAC was not seen to enhance its activity.     

In vitro analysis of an new saliva substitute (Saliva natura) on enamel and dentin

BACKGROUND: Hyposalivation is an important chronic side effect of radiotherapy in the head and neck area, and patients often alleviate their symptoms using saliva substitutes. The aim of this study was to evaluate the effects of two commercially available saliva substitutes (Saliva natura and Glandosane) on the mineral loss of bovine enamel and dentin in vitro. An aqueous remineralization solution served as control. METHODS: Each 45 bovine enamel and dentin specimens were prepared. Prior to (control of sound dentin) and after (control of demineralized dentin) demineralization (37 degrees C; enamel: pH 4.95; 14 d; dentin: pH 5.0; 7 d) one third of each specimens surface was covered with nail varnish. Subsequently, the specimens (n = 15) were exposed to Glandosane and Saliva natura as well as a remineralization solution for 14 days (37 degrees C). Specimens were examined using transversal microradiography. RESULTS: Compared to Saliva natura and the reminerlization solution, Glandosane induced both significantly increased mineral losses as well as lesion depths of the enamel specimens (p < 0.05; ANOVA, Bonferroni). After exposure of the dentin specimens to Saliva natura a significantly increased mineral loss could be observed (p < 0.001), whereas no differences in mineral loss could be observed for the enamel specimens (p = 0.078; t-test). CONCLUSIONS: Within the limitations of an in vitro study it can be concluded that Glandosane revealed a demineralizing potential on bovine enamel as well as on dentin and should not be recommended for dentate patients. Since Saliva natura has a demineralizing effect on dentin, a further improvement regarding the remineralizing capacity would be desirable.     

Oral microbiota and host innate immune response in bisphosphonate-related osteonecrosis of the jaw

Bacterial biofilms have emerged as potential critical triggers in the pathogenesis of bisphosphonate（BP）-related osteonecrosis of the jaw（ONJ） or BRONJ. BRONJ lesions have shown to be heavily colonized by oral bacteria, most of these difficult to cultivate and presents many clinical challenges. The purpose of this study was to characterize the bacterial diversity in BRONJ lesions and to determine host immune response. We examined tissue specimens from three cohorts（n530）; patients with periodontal disease without a history of BP therapy（Control, n510）, patients with periodontal disease having history of BP therapy but without ONJ（BP, n55） and patients with BRONJ（BRONJ, n515）. Denaturing gradient gel electrophoresis of polymerase chain reaction（PCR）-amplified 16 S r RNA gene fragments revealed less bacterial diversity in BRONJ than BP and Control cohorts. Sequence analysis detected six phyla with predominant affiliation to Firmicutes in BRONJ（71.6%）, BP（70.3%） and Control（59.1%）. Significant differences（P,0.05） in genera were observed, between Control/BP, Control/BRONJ and BP/BRONJ cohorts. Enzyme-linked immunosorbent assay（ELISA）results indicated that the levels of myeloperoxidase were significantly lower, whereas interleukin-6 and tumor necrosis factor-alpha levels were moderately elevated in BRONJ patients as compared to Controls. PCR array showed significant changes in BRONJ patients with downregulation of host genes, such as nucleotide-binding oligomerization domain containing protein 2, and cathepsin G, the key modulators for antibacterial response and upregulation of secretory leukocyte protease inhibitor, proteinase 3 and conserved helix–loop–helix ubiquitous kinase. The results suggest that colonization of unique bacterial communities coupled with deficient innate immune response is likely to impact the pathogenesis of ONJ.     

Evaluation of zirconia–porcelain interface using X-ray diffraction

The aim of this study was to determine if accelerated aging of porcelain veneering had an effect on the surface properties specific to a tetragonal-to-monoclinic transformation (TMT) of zirconia restorations. Thirty-six zirconia samples were milled and sintered to simulate core fabrication followed by exposure to various combinations of surface treatments including as-received (control), hydrofluoric acid (HF), application of liner plus firings, application of porcelain by manual layering and pressing with firing, plus accelerated aging. The quantity of transformed tetragonal to monoclinic phases was analyzed utilized an X-ray diffractometer and one-way analysis of variance was used to analyze data. The control samples as provided from the dental laboratory after milling and sintering process had no TMT (X_m = 0). There was an effect on zirconia samples of HF application with TMT (X_m = 0.8%) and liner plus HF application with TMT (X_m = 8.7%). There was an effect of aging on zirconia samples (no veneering) with significant TMT (X_m = 70.25%). Both manual and pressing techniques of porcelain applications reduced the TMT (manual, X_m = 4.41%, pressing, X_m = 11.57%), although there was no statistical difference between them. It can be concluded that simulated applications of porcelain demonstrated the ability to protect zirconia from TMT after aging with no effect of a liner between different porcelain applications. The HF treatment also caused TMT.     

Influence of acrylamide monomer addition to the acrylic denture-base resins on mechanical and physical properties

The aim of the study was to evaluate the effect of adding acrylamide monomer （AAm） on the characterization, flexural strength, flexural modulus and thermal degradation temperature of poly（methyl methacrylate） （PMMA） denture-base resins. Specimens （n= 10） were fabricated from a conventional heat-activated QC-20 （Qc-） and a microwave heat-activated Acron MC （Ac-） PMMA resins. Powder/ liquid ratio followed the manufacturer＇s instructions for the control groups （Qc-c and Ac-c） and for the copolymer groups, the resins were prepared with 5% （-5）, 10% （- 10）, 15% （- 15） and 20% （-20） acrylamide contents, according to the molecular weight ratio, respectively. The flexural strength and flexural modulus were measured by a three-point bending test. The data obtained were statistically analyzed by Kruskal-Wallis test （a=O.05） to determine significant differences between the groups, The chemical structures of the resins were characterized by the nuclear magnetic resonance spectroscopy. Thermal stabilities were determined by thermogravimetric analysis （TGA） with a heating rate of 10 ~C.min-1 from 35 ~C to 600 ~C. Control groups from both acrylic resins showed the lowest flexural strength values. Qc-15 showed significant increase in the flexural strength when compared to Qc-c （P〈O.01）. Ac-10 and Ac-15 showed significance when compared to Ac-c （P〈O.01）. Acrylamide incorporation increased the elastic modulus in Qc-10, Qc-15 and Qc-20 when compared to Qc-c （P〈0.01）. Also significant increase was observed in Ac-10, Ac-15 and Ac-20 copolymer groups when compared to Ac-c （P〈0.01）. According to the 1H-nuclear magnetic resonance （NMR） results, acrylamide copolymerization was confirmed in the experimental groups. TGA results showed that the thermal stability of PMMA is increased by the insertion of AAm.     

Incidence of C-shaped root canal systems in mandibular second molars in the native Chinese population by analysis of clinical methods

The aims of the study were to investigate the incidence of C-shaped root canal systems in mandibular second molars in a native Chinese population using radiography and clinical examination under microscope and to compare the relative efficacies of these methods.For the recognition of C-shaped root canal system,1 146 mandibular second molars were selected and examined.Teeth with C-shaped canal systems were categorized by using the radiographic classification criteria and the modified Melton’s method.C-shaped canals were identified in 397(34.64%) mandibular second molars by radiography(type I,31.23%;type II,38.29%;type III,30.48%).Clinical examination showed that 449(39.18%) cases exhibited C-shaped canal systems(C1,22.94%;C2,48.11%;C3a,15.59%;C3b,13.36%).As for the result of the radiographic and clinical combined examination,C-shaped root canals were found in 473(41.27%) mandibular second molars(C1,21.78%;C2,45.67%;C3a,16.70%;C3b,15.86%).The incidence of C-shaped root canal diagnosed by radiographic method was statistically different from that by clinical examination and the combined examination(P,0.05).The study indicated a high incidence of C-shaped canal system in a Chinese population.The combination of microscopic and radiographic examination is an effective method in identifying the C-shaped root canal system.     

Human Papillomavirus as an Independent Predictor in Oral Squamous Cell Cancer

Aim There is an increasing evidence for the role of high risk human papillomavirus （HPV） in the pathogenesis of oral squamous cell carcinoma （OSCC）. The purpose of this study is to evaluate the relevance of HPV infection to the survival and prognosis of OSCC. Methodology Fifty-two patients with OSCC were followed from 4 to 88 months with a median of 50.7 months. HPV DNA was identified in formalin-fixed, paraffin-embedded tumor specimens by nested PCR with MY09/MY11 and GP5^＋/GP6^＋ primer pairs and the HPV genotype was determined by direct DNA sequencing. Association between the HPV status and risk factors for cancer as well as tumor-host characteristics were analyzed.Survival curves were calculated by the Kaplan-Meier method and analyzed using the log-rank test. Results HPV was found in 40.4% of the tumors with HPV16 accounting for 63.5%, HPV18 for 30.8%, HPV6 for 3.9% and HPVll for 1.8%. No infection with more than one HPV genotype was detected. HPV infection was significantly associated with poor histological grade, TNM stage Ⅰ -Ⅱ, alcohol usage and no smoking status. Multivariate analysis showed that HPV had an independent prognostic effect on the overall survival after adjusting other confounding factors such as histological grade, TNM stage and tobacco usage. The presence of HPV was significantly correlated with a better survival in patients with OSCC. Conclusion HPV infection can act as an independent predictor for the survival and prognosis of OSCC.     

Successful Treatment of Postpeak Stage Patients with Class Ⅱ Division 1 Malocclusion Using Non-extraction and Multiloop Edgewise Archwire Therapy： A Report on 16 Cases

Aim To determine cephalometrically the mechanism of the treatment effects of non-extraction and multiloop edgewise archwire （MEAW） technique on postpeak Class Ⅱ Division 1 patients.
Methodology In this retrospective study, 16 postpeak Class Ⅱ Division 1 patients successfully corrected using a non-extraction and MEAW technique were cephalometrically evaluated and compared with 16 matched control subjects treated using an extraction technique. Using CorelDRAW software, standardized digital cephalograms preand post-active treatments were traced and a reference grid was set up. The superimpositions were based on the cranial base, the mandibular and the maxilla regions,and skeletal and dental changes were measured. Changes following treatment were evaluated using the paired-sample t-test. Student＇s t-test for unpaired samples was used to assess the differences in changes between the MEAW and the extraction control groups.
Results The correction of the molar relationships comprised 54% skeletal change （mainly the advancement of the mandible） and 46% dental change. Correction of the anterior teeth relationships comprised 30% skeletal change and 70% dental change.
Conclusion The MEAW technique can produce the desired vertical and sagittal movement of the tooth segment and then effectively stimulate mandibular advancement by utilizing the residual growth potential of the condyle.     

Effect of colouring green stage zirconia on the adhesion of veneering ceramics with different thermal expansion coefficients

This study evaluated the adhesion of zirconia core ceramics with their corresponding veneering ceramics, having different thermal expansion coefficients （TECs）, when zirconia ceramics were coloured at green stage. Zirconia blocks （N=240; 6 mm x 7 mm x 7 mm） were manufactured from two materials namely, ICE Zirconia （Group 1） and Prettau Zirconia （Group 2）. In their green stage, they were randomly divided into two groups. Half of the specimens were coloured with colouring liquid （shade A2）, Three different veneering ceramics with different TEC （ICE Ceramic, GC Initial Zr and IPS e.max Ceram） were fired on both coloured and non-coloured zirconia cores. Specimens of high noble alloys （Esteticor Plus） veneered with ceramic （VM 13） （n= 16） acted as the control group. Core-veneer interface of the specimens were subjected to shear force in the Universal Testing Machine （0.5 mm-min-1）. Neither the zirconia core material （P=0.318） nor colouring （P=0.188） significantly affected the results （three-way analysis of variance, Tukey＇s test）. But the results were significantly affected by the veneering ceramic （P=0.000）. Control group exhibited significantly higher mean bond strength values （45.7__.8） MPa than all other tested groups （（27.1__.4.1）-（39.7__.4.7） and （27.4__.5.6）-（35.9___4.7） MPa with and without colouring, respectively） （P~0.001）. While in zirconia-veneer test groups, predominantly mixed type of failures were observed with the veneering ceramic covering ~ 1/3 of the substrate surface, in the metal-ceramic group, veneering ceramic was left adhered 1/3 of the metal surface. Colouring zirconia did not impair adhesion of veneering ceramic, but veneering ceramic had a significant influence on the core-veneer adhesion. Metal-ceramic adhesion was more reliable than all zirconia-veneer ceramics tested.     

Porous titanium granules in critical size defects of rabbit tibia with or without membranes

Recently, porous titanium granules （PTGs） have been indicated for the preservation of the dimensions of post-extraction sockets, as a filler in sinus lift procedures and for the treatment of peri-implant and periodontal defects, based on the osteoconductivity and dimensional stability of the titanium granules. However, there is a lack of information regarding the use of this material in larger defects and in conjunction with membranes. The objective of this study is to test the behavior of PTGs used to fill critical size defects in rabbit tibiae, with and without membranes. Critical defects were created in both tibiae of rabbits, divided randomly into three groups： Group A （defect filled with PTG）, Group B （defect filled with PTG＋collagen membrane） and a control group （empty defect）. After six weeks, histomorphometric analysis was performed. The results showed more defect closures at the cortical area （87.37%±2.2%） and more bone formation at the marrow area （57.6%± 1.3%） in Group B, in comparison with the other groups （P〈0.05）; the use of membranes improved the material stability expressed as more percentages of the original material when membranes were used （P〈0.05）. Finally, inflammatory reactions were observed when the granules were not protected by membranes. In spite of the limitations of this animal study, it may be concluded that PTG particles are osteoconductive and allow bone growth. The PTG particles must be covered by a membrane, especially when grafting larger defects, in order to control particle migration, promote clot stabilization and separate the PTG graft from undesired soft tissue cells.     

Chemical composition of Galla chinensis extract and the effect of its main component(s) on the prevention of enamel demineralization in vitro

To determine the chemical composition of Galla chinensis extract(GCE) by several analysis techniques and to compare the efficacy of GCE and its main component(s) in inhibition of enamel demineralization,for the development of future anticaries agents,main organic composition of GCE was qualitatively determined by liquid chromatography-time of flight-mass spectrometry(LC-TOF-MS) and quantified by high-performance liquid chromatography-diode array detector(HPLC-DAD).Inorganic ions were tested by inductively coupled plasma-atomic emission spectroscopy and F was especially measured by ion chromatography.Then,bovine enamel blocks were randomly divided into four treatment groups and were subjected to a pH-cycling regime for 12 times.Each cycle included 5-min applications with one of four treatments:4 g?L 21 GCE solution,4 g?L 21 gallic acid(GA) solution,1 g?L 21 NaF solution(positive control),deionized water(DDW,negative control),and then 60-min application in pH 5.0 acidic buffer and 5-min application in neutral buffer.Acidic buffers were retained for calcium analysis.The main organic composition of GCE were GA and its isomer,and,to a lesser extent,small molecule gallotannins.The content of GA in GCE was 71.3%60.2%(w/w).Inorganic ions were present in various amounts,of which Ca was(13662.82) mg?g 21,and Zn was(6.860.1) mg?g 21.No F was detected in GCE.In pH cycling,GA showed an effect similar to GCE in inhibiting enamel demineralization(P.0.05).GA was found to be the main effective,demineralization inhibiting component of GCE and could be a promising agent for the development of anticaries agents.     

The biomechanical role of periodontal ligament in bonded and replanted vertically fractured teeth under cyclic biting forces

After teeth are replanted,there are two possible healing responses:periodontal ligament healing or ankylosis with subsequent replacement resorption.The purpose of this study was to compare the fatigue resistance of vertically fractured teeth after bonding the fragments under conditions simulating both healing modes.Thirty-two human premolars were vertically fractured and the fragments were bonded together with Super-Bond C&B.They were then randomly distributed into four groups(BP,CP,CA,BA).The BP and CP groups were used to investigate the periodontal ligament healing mode whilst the BA and CA groups simulated ankylosis.All teeth had root canal treatment performed.Metal crowns were constructed for the CP and CA groups.The BP and BA groups only had composite resin restorations in the access cavities.All specimens were subjected to a 260 N load at 4 Hz until failure of the bond or until 2 x 106 cycles had been reached if no fracture occurred.Cracks were detected by stereomicroscope imaging and also assessed via dye penetration tests.Finally,interfaces of the resin luting agent were examined by scanning electron microscope.The results confirmed that the fatigue resistance was higher in the groups with simulated periodontal ligament healing.Periodontal reattachment showed important biomechanical role in bonded and replanted vertically fractured teeth.     

Isolation and characterisation of human gingival margin-derived STRO-1/MACS~+ and MACS~-cell populations

Recently,gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting(MACS) showed remarkable periodontal regenerative potential in vivo.As a second-stage investigation,the present study’s aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive(MACS~+) and STRO-1-negative(MACS~-) cell populations from the human free gingival margin.Cells were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 antibodies.Subsequently,the MACS~+ and MACS~- cell fractions were characterized by flow cytometry for expression of CD14,CD34,CD45,CD73,CD90,CD105,CD146/MUC18 and STRO-1.Colony-forming unit(CFU) and multilineage differentiation potential were assayed for both cell fractions.Mineralisation marker expression was examined using real-time polymerase chain reaction(PCR).MACS~+ and MACS- cell fractions showed plastic adherence.MACS~+ cells,in contrast to MACS- cells,showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs(P<0.01).More than 95%of MACS~+ cells expressed CD105,CD90 and CD73;lacked the haematopoietic markers CD45,CD34 and CD14,and expressed STRO-1 and CD146/MUC18.MACS- cells showed a different surface marker expression profile,with almost no expression of CD14 or STRO-1,and more than 95%of these cells expressed CD73,CD90 and CD146/MUC18,as well as the haematopoietic markers CD34 and CD45 and CD105.MACS~+ cells could be differentiated along osteoblastic,adipocytic and chondroblastic lineages.In contrast,MACS- cells demonstrated slight osteogenic potential.Unstimulated MACS~+ cells showed significantly higher expression of collagen I(P<0.05) and collagen III(P<0.01),whereas MACS~- cells demonstrated higher expression of osteonectin(P<0.05;MannWhitney).The present study is the first to compare gingival MACS~+ and MACS- cell populations demonstrating that MACS~+ cells,in contrast to MACS- cells,harbour stem/progenitor cell characteristics.This study also validates the effectiveness of the STRO-l/MACS~+technique for the isolation of gingival stem/progenitor cells.Human free gingival margin-derived STRO-1/MACS~+ cells are a unique renewable source of multipotent stem/progenitor cells.     

Effect of Botulinum Toxin Type A on a Rat Surgical Wound Model

Objectives

The tension on a wound is one of the important factors that determine the degree of fibrosis and scar formation. We hypothesized that local botulinum toxin type A (Botox) induced paralysis of the musculature subjacent to a surgical wound with a skin defect would minimize the repetitive tensile forces on the surgical wound''s edges, and this will result in a decreased fibroplastic response and fibrosis of the wound.

Methods

This is a prospective randomized experimental study. Two distinct surgical wounds were made to the dorsum of 15 adult rats, respectively. One of the 2 wounds was injected with Botox, and the other wound was used as a control, and this was done for all the rats'' wounds. We evaluated the wound size, the degree of fibrosis and inflammation, the blood vessel proliferation, the thickness of the wound and the expression of transforming growth factor (TGF)-β1 in the wounds.

Results

There were significant differences of wound size at the 3rd and 4th week between the Botox and control groups (P<0.05). The Botox group showed less infiltration of inflammatory cells than the control group at the 2nd week (P<0.05). The Botox group showed a smaller number of fibroblasts and less fibrosis than the control group at the 4th week (P<0.05). The Botox group showed much strong collagen density than the control group at the 8th week (P<0.05). For the immunohistochemical staining, there was a lower transforming growth factor (TGF)-β1 expression in the Botox group than that of the control group at the 4th week (P<0.05).

Conclusion

The wounds of the Botox-treated group showed a larger wound size, less infiltration of inflammatory cells and less fibrosis, a much greater amount of collagen and a lower expression of TGF-β1 than did the control group. Botox might be used to decrease the fibrosis of a surgical wound without damaging the epithelial growth in situations for which decreased fibrosis is necessary, such as for treating laryngeal, tracheal and nasal stenosis.     

Einsatz von Hautklebern in der Kopf-Hals-Chirurgie

Background

In this work cyanoacrylate-based skin adhesives used in Germany for skin closure in head and neck surgery are compared with respect to ease of application, cost-effectiveness and cosmetic results.

Patients and materials

We compared 25 wounds sealed with a skin adhesive with 25 suture-sealed wounds.

Results

Bonding of surgical wounds with glue had a high level of acceptance in all patients. The tedious, time-consuming and sometimes painful postoperative removal of many sutures in patients is omitted. Patients can shower soon afterwards without additional protection as the adhesive provides a waterproof barrier. Problems of wound healing can immediately be detected through the transparent skin adhesive. Cosmetic long-term results of skin closure by adhesives are comparable to suture-sealed wounds.

Conclusions

The adhesives available on the market differ mainly in the form of the applicator, the viscosity on application, as well as the strength after hardening. The application is easy to implement and significantly faster than conventional suturing. Apart from the cost savings of materials compared to the use of skin sutures and investment of Steri-Strips?, expensive anesthesia and surgical time can also be saved.