E-Chin Shen

Chitosan inhibits prostaglandin E2 formation and cyclooxygenase-2 induction in lipopolysaccharide-treated RAW 264.7 macrophages.

Chitosan, a deacetylated chitin, has been reported to accelerate the wound healing and exert anti-inflammatory effect but the possible mechanisms involved are still unclear. Enhanced production of prostaglandin E2 (PGE2) and pro-inflammatory cytokines has been shown to contribute to immunosuppression and cytotoxicity during wound healing. In this study, we examined the effect of chitosan on cyclooxygenase pathway and cytokines production in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. Our results first demonstrated that chitosans (MW=50,000, 150,000 or 300,000) significantly inhibit the overproduction of PGE2 as well as cyclooxygenase-2 (COX-2) protein expression and activity accompanied by attenuation of pro-inflammatory cytokines production such as tumor necrosis factor-alpha and interleukin-1beta formation but increase of the anti-inflammatory cytokine, IL-10, formation in LPS-treated RAW 264.7 macrophages. These results suggest that the beneficial effect of chitosan on wound healing may be associated, at least partly, with the inhibition of PGE2 production by suppressing COX-2 induction and activity as well as attenuation of pro-inflammatory/anti-inflammatory cytokines ratio in activated macrophages.

Three‐dimensional analysis of the root morphology of mandibular first molars with distolingual roots

AIM To determine the prevalence of distolingual roots in mandibular first molar teeth in Taiwanese Han Chinese, and its impact on root morphology. METHODOLOGY The presence of distolingual roots in 375 subjects (521 molars) were assessed from 624 patients attending the dental clinics of medical centres around Taiwan island from August 2004 to April 2007 using computed tomography. The following observations were made: (i) numbers of roots and canals, (ii) mesial and distal root types and (iii) levels of furca in the molars presence or absence of distolingual root. RESULTS The mean age of the subject was 45; 43% were women. Among all the examined molars, 56%, 27% and 18% were two-, three- and four-rooted, respectively. Two per cent, 72% and 26% of molars had two, three and four canals, respectively. All of the four-rooted molars had four canals, but all of the molars with four canals varied in the number of roots. All molars with distolingual roots had two mesial canals. Bilateral consistency in terms of distolingual root, root canal number, root number and root type was observed in subjects with bilateral molars. In molars with distolingual roots, a higher prevalence of two mesial roots and a shorter mesial root trunk were observed than in teeth without distolingual roots. CONCLUSIONS A distolingual root was found in 22% of molars and in 24% of the subjects examined. Most subjects with a distolingual root had them bilaterally. The presence of a distolingual root was associated with variation in the root morphology, including the furcation level, the root type and the number of roots and canals.

Bifid mandibular canals and the factors associated with their presence: a medical computed tomography evaluation in a Taiwanese population

OBJECTIVES To examine distribution of bifid mandibular canals in a Taiwanese population and to evaluate factors contributing to the phenomenon. MATERIAL AND METHODS Computed tomographic images from 173 subjects (97 females and 76 males) were obtained using a 64-slice multidetector computerized tomography system, and the presence of bifid mandibular canals, as well as their widths and lengths, was examined. Association of length of bifid canals with possible contributing factors, including gender, age, and side of presentation, as well as size of cross-sectional bony area of mandible along the long axis of mandibular canal, was evaluated. RESULTS Bifid mandibular canals, with mean values of 10.1 and 0.9 mm in length and width, were found in 53 (30.6%) of 173 patients and 64 (18.5%) of 346 hemi-mandibles. Bifid canals appeared more frequently and tend to penetrate mandible with greater lengths in males if compared with those in females. When males were compared with females and when mandibles with bifid canals were compared with ones without, the former tend to present with larger bony area at corresponding levels of cross-sectional plane than the later, respectively. By regression analysis, significant association was found between length of bifid canals and gender, side of hemi-mandible, and bony area at mid-zone of mandibular canal. CONCLUSIONS Bifid canals were observed in 30.6% of subjects and 18.5% of hemi-mandibles. Significant association between length of bifid canals and gender, side of hemi-mandible, and cross-sectional bony area of mandible was observed.

Prevalence and location of maxillary sinus septa in the Taiwanese population and relationship to the absence of molars

OBJECTIVES Understanding the septum structure of the sinus is necessary for correct implant placement in the maxilla if sinus encroachment is required. The exact mechanism that controls septum development is unclear, although a role for the irregular pneumatization of the sinus floor following tooth loss has been suggested. The aims of this study were to examine the prevalence and location of sinus septa in the Taiwanese population and to determine whether there is a relationship between the presence of septa and the absence of molars. MATERIALS AND METHODS Using computed tomography (CT) scans of sinuses obtained from 423 subjects (216 women and 207 men, mean age 53.65 years), septum morphology and its correlation with the presence of molars was examined. RESULTS About 30% of subjects (124/423) had sinus septa, corresponding to 20.45% of all sinus segments detected (173/846). Fifty-nine patients had multiple septa, giving a prevalence of septa of 22.93%. Septa were located most frequently in the regions of the first and second molars. The prevalence was not related to tooth loss (edentulous, partially edentulous, or dentate maxillary segments). Logistic regression analysis showed that men were significantly more likely to have septa than were women (OR=1.67; P=0.019). CONCLUSIONS In the 423 Taiwanese subjects tested, the prevalence of septum was 29.31% according to the subjects and 22.93% according to the sinus segments. The most frequent location of septa was in the region of the first and secondary molars. No correlation was observed between the presence of septa and the absence of molars.

Expression and bioactivities of endothelin-1 in gingiva during cyclosporine A treatment.

BACKGROUND AND OBJECTIVE This study aimed to evaluate the expression and bioactivities of endothelin-1 (ET-1) in gingiva during cyclosporine A (CsA) treatment. MATERIAL AND METHODS After establishing edentulous ridges, experimental rats were fed 30 mg/kg/day CsA while control animals received mineral oil for 4 weeks, after which a reverse transcription-polymerase chain reaction (RT-PCR) and/or immunohistochemistry was used to examine the expression of ET-1, its receptors, proliferating cell nuclear antigen (PCNA) and inducible nitric oxide synthase (iNOS) in gingivae. The roles of the endothelin receptors A and B (ET(A) and ET(B)) in CsA-enhanced expression of PCNA and iNOS were examined in cultured human gingival fibroblasts pretreated with receptor antagonists, by immunocytochemistry and RT-PCR, respectively. RESULTS The mRNA expression of ET-1, ET(A) and ET(B), as well as of PCNA and iNOS, was significantly greater in edentulous gingiva that received CsA compared with control gingiva. Immunohistochemistry revealed more cells positively stained for ET-1 and its receptors in the tissues of CsA-treated rats than in those of control rats. In fibroblast cultures, enhanced mRNA expression of ET-1, ET(A) and ET(B) was observed after CsA treatment at the concentrations of 10 and 100 ng/mL. Cyclosporine A-enhanced PCNA expression was somewhat reduced by blockade of ET(A), but not ET(B), whereas iNOS expression was somewhat reduced by blockade of ET(B). CONCLUSION Based on the present findings, we suggest that: (1) CsA upregulates the gingival expression of ET-1 and its receptors; and (2) ET(A) and ET(B) have different bioactivities, ET(A) being involved in cell proliferation and ET(B) being associated with iNOS expression.

Configuration and corticalization of the mandibular bifid canal in a Taiwanese adult population: a computed tomography study.

PURPOSE The configuration and degree of corticalization of bifid mandibular canals were examined using medical computed tomography (CT) images from 170 hemimandibles obtained from 308 Taiwanese adults. MATERIALS AND METHODS The configurations of the bifid canals were assessed according to their anatomical position in relation to the ramus, molars, premolars, and mental foramen; their course (anterior/posterior or superior/inferior); the presence or absence of confluence with the main mandibular canal; and the presence or absence of penetration through the mandible to form an accessory foramen. The percentage of the canal length that was corticalized was measured. Two different classifications of bifid canals were also briefly summarized and compared. RESULTS When bifid canals are present (41.2% of patients; 27.6% of hemimandibles), the bifid canals were primarily located in the ramus and retromolar regions (67.7%) running anteriorly (95.9%) and superiorly (95.9%) without confluence with the main mandibular canal (91.1%). Up to 16.5% of bifid canals form accessory foramina on the cortical surface of the mandible. Approximately 78% of the bifid canals have varied degrees of corticalization around the bifid canals. CONCLUSION The configuration and course of 170 mandibular bifid canals were evaluated with CT images. The bifid canals were primarily located in the ramus and retromolar regions; however, 32.4% of the bifid canals were located in potential positions for dental implant placement. Most of the bifid canals ran anteriorly superior to the main mandibular canal, did not rejoin with the main mandibular canal, and diminished within the mandibular body. Approximately half of the bifid canals (45%) were completely corticated.

Association of CCL5 and CCR5 Gene Polymorphisms With Periodontitis in Taiwanese

BACKGROUND It has been suggested that genetic factors may predispose individuals to periodontal diseases. The present case-control study aims to test whether the -403 single nucleotide polymorphism of chemokine ligand 5 (CCL5-403) and the 32-bp deletion of CCR5 (CCR5Δ32) polymorphisms are associated with susceptibility to chronic and aggressive periodontitis. METHODS Taiwanese participants (N = 213) were grouped into control group (CG), generalized aggressive periodontitis (GAgP), or chronic periodontitis (CP) groups. DNA samples were obtained from peripheral blood. CCL5-403, evaluated by polymerase chain reaction-restriction fragment length polymorphism, and CCR5Δ32, evaluated by polymerase chain reaction, were compared among the three groups. RESULTS There was a significant association between type of periodontitis and having allele A or G in the CCL5-403 polymorphism. GAgP patients were 3.7 times more likely than CP patients and 2.0 times more likely than CG patients to have allele A, instead of allele G, in CCL5-403. GAgP patients were 3.1 times more likely than CG patients to have AG versus GG genotype. GAgP patients were also 5.0 and 19.8 times more likely than CP patients to have AG and AA genotypes, respectively, compared to GG. For the CCR5Δ32 polymorphism, no association was found between the type of periodontitis and having different genotype or allele distributions among GAgP, CP, or CG patients. CONCLUSION The single nucleotide polymorphism of CCL5-403 G substitution by A may play a role in AgP; however, the CCR5Δ32 polymorphism may not.

Role of Shh and TGF in cyclosporine-enhanced expression of collagen and α-SMA by gingival fibroblast.

OBJECTIVE Cyclosporine-A (CsA)-induced gingival overgrowth may arise from an alteration in stoma matrix homeostasis. Sonic hedgehog (Shh) plays a key role during embryogenic development and fibrotic progression, and may be involved in CsA-altered gingival matrix homeostasis. METHODS Using the reverse transcription-polymerase chain reaction and Western blot analysis, we investigated the mRNA and protein expressions of Shh, type 1 collagen (COL1), alpha-smooth muscle actin (α-SMA) and transforming growth factor-beta (TGF-β) in human gingival fibroblasts after CsA treatments. The effect of Shh on CsA-induced alterations was further evaluated by the extra-supplement or inhibition of Shh or TGF-β. RESULTS Cyclosporine-A enhanced COL1, α-SMA, Shh and TGF-β expressions in human gingival fibroblasts. The exogenous Shh/TGF-β augmented the expression of COL1 and α-SMA, and the Shh/TGF-β inhibition suppressed the CsA-enhanced COL1 and α-SMA expressions. Moreover, Shh mRNA and protein expressions increased if extra-supplementing the exogenous TGF-β, whereas the CsA-upregulated Shh was mitigated by the TGF-β pathway inhibitor. However, neither exogenous Shh nor the Shh pathway inhibitor alters TGF-β expression or CsA-up-regulated TGF-β expression. CONCLUSIONS Shh, regulated by TGF-β, mediates CsA-altered gingival matrix homeostasis.

The impact of medical institutions on the treatment decisions and outcome of root-resected molars: A retrospective claims analysis from a representative database

Background: This study analyzes the prognostic factors affecting the survival rate of root-resected molars by using a representative population-based dataset. Materials and Methods: A total of 635,216 eligible patients were enrolled from a representative cohort composed of one million of Taiwans population. The tooth-related factors influencing the survival rates of root-resected teeth were examined on 516 molars, in 492 patients. Cox regression was performed to statistically analyze the factors. Results: The overall survival rate for the root-resected molars was 91.7%. Of the analyzed factors with respect to root-resection procedures, whether or not concomitant flap surgery was performed in the medical institutions, the dental arch and tooth location demonstrated a considerable influence on the treatment and decision-making. The main reasons and results of root-resected molars receiving root-resection therapy in hospitals were the periodontal-compromised conditions, whereas, the root-resected molars that received root-resection therapy in private practice clinics were caused by caries/endodontic reasons. After adjusting for other factors, in the outcome of root-resected molars, a higher risk of extraction occurrence was seen in hospitals than in private practice clinics (hazard ratio = 2.03; 95% CI = 1.04 to 3.98; P = 0.039). Conclusions: Of the analyzed prognostic factors, medical institutions significantly affect the treatment decision and survival of root-resected molars. Therefore, a comprehensive evaluation, risk assessment, and treatment plan should be executed before the root-resection procedure is performed.

Correlation Between Resonance Frequency Analysis and Bone Quality Assessments at Dental Implant Recipient Sites.

PURPOSE To evaluate whether primary implant stability could be used to predict bone quality, the association between the implant stability quotient (ISQ) value and the bone type at the implant site was evaluated. MATERIALS AND METHODS Ninety-five implant sites in 50 patients were included. Bone type (categorized by Lekholm and Zarb) at the implant site was initially assessed using presurgical dental radiography. During the preparation of the implant site, a bone core specimen was carefully obtained. The bone type was assessed by tactile sensation during the drilling operation, according to the Misch criteria. The primary stability of the inserted implant was evaluated by resonance frequency analysis (RFA). The ISQ value was recorded. The bone core specimen was then examined by stereomicroscopy or microcomputed tomography (micro-CT), and the bone type was determined by the surface characteristics of the specimen, based on Lekholm and Zarb classification. Agreement between the bone quality assessed by the four methods (ie, presurgical radiography, tactile sensation, stereomicroscopy, and micro-CT) was tested by Cohens kappa statistics, whereas the association between the ISQ value and the bone type was evaluated by the generalized linear regression model. RESULTS The mean ISQ score was 72.6, and the score was significantly influenced by the maxillary or mandibular arch (P = .001). The bone type at the implant sites varied according to the assessment method. However, a significant influence of the arch was repeatedly noted when using radiography or tactile sensation. Among the four bone-quality assessment methods, a weak agreement existed only between stereomicroscopy and micro-CT, especially in the maxilla (κ = 0.469). A negative association between the ISQ value and the bone type assessed by stereomicroscopy or by micro-CT was significant in the maxilla, but not in the mandible, after adjustments for sex, age, and right/left side (P = .013 and P = .027 for stereomicroscopy and micro-CT, respectively). CONCLUSION The ISQ value was weakly associated with the bone type when assessed by stereomicroscopy or micro-CT in the maxilla. Caution is necessary if RFA is used as a tool to evaluate bone quality at the implant site, especially in the mandible.