Silk-based nerve guidance conduits with macroscopic holes modulate the vascularization of regenerating rat sciatic nerve

Peripheral nerve injuries induce a severe motor and sensory deficit. Since the availability of autologous nerve transplants for nerve repair is very limited, alternative treatment strategies are sought, including the use of tubular nerve guidance conduits(tNGCs). However, the use of tNGCs results in poor functional recovery and central necrosis of the regenerating tissue, which limits their application to short nerve lesion defects(typically shorter than 3 cm). Given the importance of vascularization in nerve regeneration, we hypothesized that enabling the growth of blood vessels from the surrounding tissue into the regenerating nerve within the tNGC would help eliminate necrotic processes and lead to improved regeneration. In this study, we reported the application of macroscopic holes into the tubular walls of silk-based tNGCs and compared the various features of these improved silk^(+) tNGCs with the tubes without holes(silk^(–) tNGCs) and autologous nerve transplants in an 8-mm sciatic nerve defect in rats. Using a combination of micro-computed tomography and histological analyses, we were able to prove that the use of silk^(+) tNGCs induced the growth of blood vessels from the adjacent tissue to the intraluminal neovascular formation. A significantly higher number of blood vessels in the silk^(+) group was found compared with autologous nerve transplants and silk^(–), accompanied by improved axon regeneration at the distal coaptation point compared with the silk^(–) tNGCs at 7 weeks postoperatively. In the 15-mm(critical size) sciatic nerve defect model, we again observed a distinct ingrowth of blood vessels through the tubular walls of silk^(+) tNGCs, but without improved functional recovery at 12 weeks postoperatively. Our data proves that macroporous tNGCs increase the vascular supply of regenerating nerves and facilitate improved axonal regeneration in a short-defect model but not in a critical-size defect model. This study suggests that further optimization of the macroscopic holes silk^(+) tNGC approach containing macroscopic holes might result in improved grafting technology suitable for future clinical use.

Amylase intrapancreatic infusion delays insulin release during an intravenous glucose tolerance test,proof of acini–islet–acinar interactions

BACKGROUND The possible existence of an acini–islet–acinar(AIA)reflex,involving mutual amylase and insulin interactions,was investigated in the current acute experiment on pigs.AIM To confirm the existence of an AIA reflex and justify the placement of the exocrine and endocrine pancreatic components within the same organ.METHODS The study was performed on six pigs under general anesthesia.An intravenous glucose tolerance test was performed,with a bolus infusion of 50%glucose to the jugular vein,while amylase(5000 U/kg)or vehicle intrapancreatic infusions were administered via the pancreaticoduodenalis cranialis artery during 30 min with a 1 mL/min flow rate.RESULTS The amylase infusion to pancreatic arterial circulation inhibited and delayed the insulin release peak which is usually associated with the highest value of blood glucose and is typically observed at 15 min after glucose infusion,for>1 h.The intrapancreatic infusion of the vehicle(saline)did not have any effect on the time frame of insulin release.Infusion of 1%bovine serum albumin changed the insulin release curve dramatically and prolonged the high range of insulin secretion,far beyond the glucose peak.CONCLUSION Intrapancreatic arterial infusion of amylase interrupted the integrated glucose–insulin interactions.This confirms an AIA reflex and justifies placement of the exocrine and endocrine pancreatic components within the same organ.

Current Concepts in Restorative Implant Dentistry

Patients today are increasingly aware of dental implants,and their expectations are for esthetically and functionally pleasing implant restorations that mimic natural teeth.This presentation will give both the experienced and novice practitioner a better understanding of how restorative implant dentistry has evolved.Treatment planning and restorative options for single implants,multiple implants and fully edentulous arches will be discussed,and the use of modern materials and CADCAM technology in fabricating the most contemporary fixed implant supported prostheses will be demonstrated.

Application of Scanning Acoustic Microscopy for Detection of Dental Caries Lesion

Introduction: A scanning acoustic microscope (SAM) is an apparatus for imaging acoustic properties. This apparatus can non-invasively and rapidly evaluate the hardness of materials in the elastic region. This device shows great potential for the diagnosis of dental caries in the clinical setting. However, since the tissue elastic modulus measured using a SAM is a property of the elastic region and the Knoop hardness is a property of the plastic region, the hardness properties differ completely. Therefore, we investigated whether the acoustic impedance measured using a SAM is related to the Knoop hardness, which is used as the standard for removal of carious dentin. Method: Polished sections were prepared from 20 extracted carious wisdom teeth. The acoustic impedance and Knoop hardness were measured for each section. In addition to comparing carious and healthy dentin in SAM images, we evaluated the difference between the carious and healthy dentin in terms of the acoustic impedance and Knoop hardness. We also evaluated the correlation between the Knoop hardness and acoustic impedance. Results: The SAM images were visualized as two-dimensional color images based on the acoustic impedance values. The mean acoustic impedance of carious dentin was significantly lower than that of healthy dentin, showing a similar trend as Knoop hardness. A strong correlation was observed between the two. Discussion: The acoustic impedance values obtained through acoustic microscopy differed significantly between carious and sound dentin. Both types of dentins were visualized using two-dimensional color images. A strong correlation was observed between the acoustic impedance value, which indicates the hardness of the elastic region, and the Knoop hardness, which indicates the hardness of the plastic region. The results of the present study indicate that acoustic impedance accurately reflects the hardness of dentin.

电动牙刷与手动牙刷对口腔卫生的效果比较

目的对电动牙刷和手动牙刷在去除菌斑、维护牙龈健康、对色素和牙结石的作用、可靠性、不良作用和成本等进行比较.方法计算机检索Cochrane口腔健康协作组临床试验资料库(截至2004年6月17日)、Cochran临床对照试验中心资料库(Cochrane图书馆2004第2期)、MEDLINE(1966～2004)、EMBASE(1980～2004第2周)和CINAHL(1982～2004第2周),并与制造商联系以获取更多资料.根据下列标准纳入随机对照试验:随机分配研究对象;参加者为手运动无障碍的普通人群;干预措施为无监督的手动或电动牙刷刷牙,至少4周;主要结局指标为试验期间菌斑和牙龈炎的变化.由6个作者独立评价并纳入研究资料.用随机效应模型进行Meta分析,用标准化均数差(SMD)及其95%CI测量效果.检查可能的异质性来源,并针对研究质量和发表偏倚进行敏感性分析.为便于讨论,将SMD转换为百分率.结果对包含3 855例研究对象的42个试验进行系统评价,结果显示,旋转振动型电动牙刷去除菌斑和减低牙龈炎的效果在短期内明显优于手动牙刷,并在3个月以上的研究中显示降低了牙龈炎指数.在1～3个月的研究中,菌斑SMD为-0.43 [95%CI (-0.72, 0.14)],牙龈炎SMD为-0.62 [95%CI (-0.90, 0.34)],Quigley Hein菌斑指数降低11%,Loe and Silness龈炎指数降低6%.在3个月以上的研究中,菌斑指数SMD为-1.29 [95%CI (-2.67, 0.08)], 龈炎指数为-0.51 [95%CI (-1.76, 0.25)],Ainamo Bay探诊出血指数降低17%.短期研究之间有异质性,敏感性分析显示当选择高质量的研究时结果是肯定的,没有证据表明有发表偏倚.采取其他设计的电动牙刷并不比手动牙刷更优.对成本、可靠性和不良作用的报道不一致,已报道的不良作用都是局限的、暂时的.结论旋转振动型电动牙刷去除牙菌斑、减少牙龈炎的效果优于手动牙刷.遵守方法学指南和更标准化的设计有益于将来的研究和Meta分析.

Immunomodulatory properties of dental tissue-derived mesenchymal stem cells: Implication in disease and tissue regeneration

Mesenchymal stem cells(MSCs)are considered as an attractive tool for tissue regeneration and possess a strong immunomodulatory ability.Dental tissuederived MSCs can be isolated from different sources,such as the dental pulp,periodontal ligament,deciduous teeth,apical papilla,dental follicles and gingiva.According to numerous in vitro studies,the effect of dental MSCs on immune cells might depend on several factors,such as the experimental setting,MSC tissue source and type of immune cell preparation.Most studies have shown that the immunomodulatory activity of dental MSCs is strongly upregulated by activated immune cells.MSCs exert mostly immunosuppressive effects,leading to the dampening of immune cell activation.Thus,the reciprocal interaction between dental MSCs and immune cells represents an elegant mechanism that potentially contributes to tissue homeostasis and inflammatory disease progression.Although the immunomodulatory potential of dental MSCs has been extensively investigated in vitro,its role in vivo remains obscure.A few studies have reported that the MSCs isolated from inflamed dental tissues have a compromised immunomodulatory ability.Moreover,the expression of some immunomodulatory proteins is enhanced in periodontal disease and even shows some correlation with disease severity.MSC-based immunomodulation may play an essential role in the regeneration of different dental tissues.Therefore,immunomodulation-based strategies may be a very promising tool in regenerative dentistry.

Intraocular pressure fluctuation and the risk of glaucomatous damage deterioration: a Meta-analysis

AIM: To systematically review whether the increased fluctuation of intraocular pressure(IOP) is a risk factor for open angle glaucoma(OAG) progression. METHODS: Scientific studies relevant to IOP fluctuation and glaucoma progression were retrieved from MEDLINE,EMBASE and CENTRAL databases, and were listed as references in this paper. The hazard ratio(HR) was calculated by using fixed or random-effects models according to the heterogeneity of included studies. RESULTS: Individual data for 2211 eyes of 2637 OAG patients in fourteen prospective studies were included in this Meta-analysis. All studies were longitudinal clinical studies with follow-up period ranging from 3 to 8.5 y. The combined HR was 1.23(95%CI 1.04-1.46, P=0.02) for the association between IOP fluctuation and glaucoma onset or progression with the evidence of heterogeneity(P<0.1).Subgroup analyses with different types of IOP fluctuation were also evaluated. Results indicated that the summary HR was 0.98(95%CI 0.78-1.24) in short-term IOP fluctuation group, which showed no statistical significance with heterogeneity, whereas, the combined HR was 1.43(95%CI1.13-1.82, P=0.003) in long-term IOP fluctuation group without homogeneity. Sensitivity analysis further showed that the pooled HR was 1.10(95%CI 1.03-1.18, P=0.004) for long-term IOP fluctuation and visual function progression with homogeneity among studies(P=0.3). CONCLUSION: Long-term IOP fluctuation can be a risk factor for glaucoma progression based on the presentedevidence. Thus, controlling the swing of IOP is crucial for glaucoma or glaucoma suspecting patients.

Input of microenvironmental regulation on colorectal cancer: Role of the CCN family

Colorectal cancer(CRC)is a major health problem causing significant morbidity and mortality.Previous results from various studies indicate that CRC tumorigenicity encompasses tumor microenvironment,emphasizing the complex interacting network between cancer cells and nearby host cells,which triggers diverse signaling pathways to promote the growth and spread ofcancer cells.The CCN family proteins share a uniform modular structure,mediating a variety of physiological functions,including proliferation,apoptosis,migration,adhesion,differentiation,and survival.Furthermore,CCN proteins are also involved in CRC initiation and development.Many studies have shown that CCN members,such as CCN1,CCN2,CCN3,Wnt-induced secreted protein(WISP)-1,WISP-2,and WISP-3,are dysregulated in CRC,which implies potential diagnostic markers or therapeutic targets clinically.In this review,we summarize the research findings on the role of CCN family proteins in CRC initiation,development,and progression,highlighting their potential for diagnosis,prognosis,and therapeutic application.

Loss of oral mucosal stem cell markers in oral submucous fibrosis and their reactivation in malignant transformation

The integrity of the basal stem cell layer is critical for epithelial homoeostasis.In this paper,we review the expression of oral mucosal stem cell markers(OM-SCMs)in oral submucous fibrosis(OSF),oral potentially malignant disorders(OPMDs)and oral squamous cell carcinoma(OSCC)to understand the role of basal cells in potentiating cancer stem cell behaviour in OSF.While the loss of basal cell clonogenicity triggers epithelial atrophy in OSF,the transition of the epithelium from atrophic to hyperplastic and eventually neoplastic involves the reactivation of basal stemness.The vacillating expression patterns of OM-SCMs confirm the role of keratins 5,14,19,CD44,β1-integrin,p63,sex-determining region Y box(SOX2),octamer-binding transcription factor 4(Oct-4),c-MYC,B-cell-specific Moloney murine leukaemia virus integration site 1(Bmi-1)and aldehyde dehydrogenase 1(ALDH1)in OSF,OPMDs and OSCC.The downregulation of OM-SCMs in the atrophic epithelium of OSF and their upregulation during malignant transformation are illustrated with relevant literature in this review.

The oral commensal Streptococcus mitis activates the aryl hydrocarbon receptor in human oral epithelial cells

Streptococcus mitis （S. mitis） is a pioneer commensal bacterial species colonizing many of the surfaces of the oral cavity in healthy individuals. Yet, not much information is available regarding its interaction with the host. We used examination of its transcriptional regulation in oral keratinocytes to elucidate some of its potential roles in the oral cavity. Transcription factor analysis of oral keratinocytes predicted S. mitis.mediated activation of aryl hydrocarbon receptor （AhR）, Activation and functionality of AhR was confirmed through nuclear translocation determined by immunofluorescence microscopy and real-time polymerase chain reaction with reverse transcription analysis of CYPIA1, the hallmark gene for AhR activation. Addition of Streptococcus mutans or Streptococcus gordonfi did not induce CYPIA1 transcription in the keratinocyte cultures. Introduction of an AhR-specific inhibitor revealed that S. mitis-mediated transcription of CXCL2 and CXCL8 was regulated by AhR. Elevated levels of pmstaglandin E2 （enzyme-linked immunosorbent assay） in supernatants from S. mitis-treated oral epithelial cells were also attenuated by inhibition of AhR activity. The observed AhR-regulated activities point to a contribution of S. mitis in the regulation of inflammatory responses and thereby to wound healing in the oral cavity. The concept that the oral commensal microbiota can induce AhR activation is important, also in view of the role that AhR has in modulation of T-cell differentiation and as an anti-inflammatory factor in macrophaees.

A handy review of carpal tunnel syndrome:From anatomy to diagnosis and treatment

Carpal tunnel syndrome(CTS) is the most commonly diagnosed disabling condition of the upper extremities. It is the most commonly known and prevalent type of peripheral entrapment neuropathy that accounts for about 90% of all entrapment neuropathies. This review aims to provide an outline of CTS by considering anat-omy, pathophysiology, clinical manifestation, diagnostic modalities and management of this common condition, with an emphasis on the diagnostic imaging evaluation.

Dental and periodontal phenotype in sclerostin knockout mice

Sclerostin is a Wnt signalling antagonist that controls bone metabolism. Sclerostin is expressed by osteocytes and cementocytes; however, its role in the formation of dental structures remains unclear. Here, we analysed the mandibles of sclerostin knockout mice to determine the influence of sclerostin on dental structures and dimensions using histomorphometry and micro-computed tomography （μCT） imaging, μCT and histomorphometric analyses were performed on the first lower molar and its surrounding structures in mice lacking a functional sclerostin gene and in wild-type controls, pCT on six animals in each group revealed that the dimension of the basal bone as well as the coronal and apical part of alveolar part increased in the sclerostin knockout mice. No significant differences were observed for the tooth and pulp chamber volume. Descriptive histomorphometric analyses of four wild-type and three sclerostin knockout mice demonstrated an increased width of the cementum and a concomitant moderate decrease in the periodontal space width. Taken together, these results suggest that the lack of sclerostin mainly alters the bone and cementum phenotypes rather than producing abnormalities in tooth structures such as dentin.

Alendronate disturbs femoral growth due to changes during immunolocalization of transforming growth factor-β1 and bone morphogenetic protein-2 in epiphyseal plate

BACKGROUND The epiphyseal growth plate is an important anatomical segment localized on the ends of a long bone.Despite the abovementioned atractive reasons for alendronate’s use,few data on the effect of alendronate during epiphyseal growth exist.AIM Verify the effect of alendronate on the growth epiphyseal plate,and compare its effect with the size of the femur during the double-staining of the immunolocalization of transforming growth factor-β1(TGF-β1)and bone morphogenetic protein-2(BMP2)in endochondral ossifing in specimens that have received alendronate.METHODS Forty newborn rats were randomly divided into two groups:a control group(were given applications of 1 mg/kg physiologic saline)and a group that received Alendronate(a dose of 2.5 mg/kg).These groups were then divided into two subgroups for euthanasia in two and 12 d of life.After euthanasia,the femurs were removed,and the femoral bones were measured linearly between the apex of the greater trochanter until the lower intercondylar midlle face to verify the probable bone growth between 3 and 12 d in control and alednroanto treated rats.Posteriorly,the surgical pieces were also sent to the histopathology laboratory to produce histological slides.The obtained slides were stained with hematoxylin and eosin to measure each of the cartilage zones in endochondral development.and other slides were immunohistochemically tested for anti-TGF-β1 and BMP-2 antibodies to investigate the immunolocalization of these proteins in the epiphyseal plaque area.RESULTS On the third day,some diferences between the control group and specimens treated with alendronate were verified.Macroscopiccaly,we found similarities in size between the femoral bones when we compared the control group with the specimens that received alendronate.On the 12^th day,the bone size of the mice receiving the drug was significantly smaller than those of the control group.These results coincide with changes in the TGF-β1 and BMP-2 expression.In the specimens that received alendronate,the TGF-β1 was expressed in some sites of trabecular bone that was neoformed,peripherally to the bone marrow area.The BMP-2 was also positive in proliferative chondrocytes and hypertrofic chondrocytes.On the 12^th day,all layers of chondrocytes exhibited positivity for BMP-2 in the specimens that received alendronate.In the interface between the trabecular bone and cartilage,an area of disorganized bone deposition was evident.Neoformed bone also appeared to be different at 12 d.In the control group,BMP-2 was positive in an intense area of bone trabeculae,whereas the alendronate-treated group showed TGF-β1 positive trabeculae and a greater bone area.CONCLUSION Alendronate alters the immunolocalization of TGF-β1 and BMP-2 simultaneously,a condition that changes the usual histological aspects of the cartilage zone and impairs epiphysis growth and femur growth.

Fixed Bicortical Screw and Blade Implants as a Non-Standard Solution to an Edentulous (Toothless) Mandible

Aim This paper deals with the treatment of an atrophied toothless mandible with a fixing bridge carried by two nonstandard implant systems. Methodology Four bicortical screws were implanted into the frontal part of the mandible and one implant on each side was placed into the distal area of the mandible as a support for a fixing bridge. Results During the years 2002–2007 the authors placed a total of 256 bicortical screw and 84 blade implants. During this period only four bicortical screws and one blade implant failed. The primary and secondary surgical success rate was therefore above 98%, while the prosthetic success rate was 100%. （Bridges which had to be re-fabricated due to implant failure were not taken into account.） Conclusion This approach is recommended as a highly successful and affordable option for a wide range of patients.

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.

Cone-Beam Computed Tomography Evaluation of the Positions of Unerupted Maxillary Canines with Incisor Root Resorption

Purpose: To establish a new coordinate system using the incisive canal and incisive foramen in cases confirmed to have root resorption in the maxillary incisor region by cone beam computed tomography (CBCT) to investigate the positions of the central and lateral incisor roots and erupting maxillary canine tooth crowns in the horizontal plane. Methods: Nine patients (two males;mean age: 10.5 years old) with suspected incisor root resorption due to erupting maxillary canines on panoramic X-ray images and in whom incisor root resorption was confirmed on CBCT images were evaluated. A control group of 12 patients with a supernumerary tooth on one side (three males;mean age: 8.6 years old) was also examined. X, Y, and Z-axes were defined, and the positions of the centers of the central incisor root (U1) and lateral incisor root (U2) and the canine cusp (U3) were examined, along with alveolar process width and length. Results: In the control group, U1, U2, and U3 were located within a certain range without overlap, while, in the incisor root resorption group, U3 overlapped with U1 and U2 and tended to deviate centrally. U2 tended to be located further posteriorly than U3. The anteroposterior diameter of the alveolar process was 1.2 mm shorter in the incisor root resorption group (p < 0.05). Conclusions: The risk of incisor root resorption accompanying canine eruption can be evaluated early by investigating the canine position on a horizontal plane established on the upper anterior tooth dentition CT images with a coordinate system using the incisive canal and incisive foramen.

Primary retinal ganglion cells for neuron replacement therapy

Optic nerve damage as a result of trauma, ischemia, glaucoma or other forms of optic neuropathy disease, leads to disconnection between the eye and brain and death of retinal ganglion cells(RGCs), causing permanent loss of vision. Therapeutic options for treating optic neuropathy are limited and represent a significant unmet medical need. Development of a regenerative strategy for replacement of lost RGCs lies at the core of the future cell-based therapy for these conditions. Successful long-term restoration of visual function depends on the type of cells for transplantation. Primary RGCs of neonatal mice are now reported to have the potential for serving such a purpose.

Tailoring Resorption Rates and Osteogenic Response in Xeno-Hybrid Bone Grafts: The Effect of Added Gelatins

Bone defects resulting from trauma,surgery,congenital malformations,and other factors are among the most common health problems nowadays.Although current strategies such as autografts and allografts are recognized as the most successful treatments for stimulating bone regeneration,limitations such as graft source and complications still exist.SmartBone?is a xeno-hybrid bone graft(made from bovine bone matrix,poly(L-lactic-co-e-caprolactone),and gelatin)with a positive clinical record for bone regen-eration.In this study,the formulation for designing xeno-hybrid bone grafts using gelatins from different sources(bovine-and porcine-derived gelatin,with bone grafts named SBN and SPK,respectively)was investigated,and the biological responses were evaluated in vitro and in vivo.The results demonstrate that gelatins from both bovine and porcine sources can be loaded onto SmartBone?successfully and safely,withstanding the aggressive manufacturing processes.Different bone cell responses were observed in vitro.SBN was found to enhance osteocalcin secretion while SPK was found to upregulate osteopontin from human osteoblasts.In vivo,both bone grafts promoted osteogenesis,but SPK degraded earlier than SBN.Our findings suggest that SBN and SPK provide different yet comparable solutions for optimizing the bone resorption and regeneration balance.These xeno-hybrid bone grafts possess ideal potential for bone defect repairing.

One stage reconstruction of large lower lip carcinoma, with local flaps

Squamous cell carcinoma (SCC) of the lower lip is a frequently diagnosed malignant pathology in the maxillofacial region. It is a slow-growing cancer, and can be diagnosed and treated easily and effectively;however, early treatment is important because its mortality rate is 10%-30%. Reconstruction for a large lower lip defect is surgically challenging, especially reconstruction with local flaps. Here, we present a 52-year-old male with a large T3 SCC, which started 13 years before this treatment and involved nearly all of his lower lip, oral commissure and upper lip. It was reconstructed by local flaps with good aesthetic and functional results. The lip was reconstructed with a combination of a Karapandzic flap on one side and a contralateral Webster cheek advancement, using a functional neck dissection on the tumor side and supraomohyoid neck dissection contralaterally. Histopathology results of the neck were negative for metastasis. We were satisfied with the aesthetic and functional results of the neck.

Stretching Induces the Rearrangement of the Periodontal Ligament Cells without Altering the Orientation of Oxytalan Fibers Relative to the Cell Axis in Vitro

The periodontal ligament (PDL) contains oxytalan fibers as well as collagen fibers, which helps it to withstand the mechanical stress to which it is constantly exposed. The oxytalan fibers are produced by PDL fibroblasts. However, the arrangement of PDL fibroblasts and the orientation of oxytalan fibers relative to the fibroblast cell axis have not been investigated under the condition of mechanical stress. We hypothesized that such stress would alter the arrangement and orientation of these cells and their oxytalan fibers. The aim of this study was to evaluate the effects of stretching strain on PDL fibroblasts, focusing on the cellular arrangement and orientation of oxytalan fibers relative to the long cell axis in cell/matrix layers by staining the major component of the fibers, fibrillin-1. The angle between the long cell axis and the oxytalan fibers was approximately 70 degrees under both non-stretching and stretching conditions. Moreover, stretching induced the rearrangement of the cells. This is the first study to demonstrate that stretching induces the rearrangement of the PDL fibroblasts without altering the angle between the long cell axis and the oxytalan fibers. These results may reflect the orientation of oxytalan fibers in the PDL under the condition of mechanical stress.