Use of an appropriate root canal irrigant is essential during endodontic treatment, due to the complex and unpredictable anatomy of the root canal system and limitations in the mechanical instrumentation techniques used to obtain a clean, bacteria-free canal. Several irrigants, such as sodium hypochlorite, chlorhexidine, hydrogen peroxide, and normal saline, have been proposed as canal system irrigants in endodontic treatment. The widely used endodontic irrigant chlorhexidine is a positively charged lipophilic/hydrophobic molecule that interacts with phospholipids and lipopolysaccharides on the bacterial cell membrane. In endodontics, its mode of antibacterial activity is determined by its concentration (0.2% or 2%). This article reviews findings from available endodontic studies on the antibacterial, antifungal, and antibiofilm activities of chlorhexidine. (J Oral Sci 56, 99-103, 2014)

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The purpose of this study was to investigate the influence of gutta-percha solvents on the bond strength of fiberglass post to root canal dentin. Forty bovine incisors were decoronated, prepared, filled, and randomly distributed into four groups (n = 10) according to the gutta-percha solvent used: control, xylene, eucalyptol and orange oil. After root canal treatment, the posts were cemented into the prepared root canals using a resin-based cement. A micro push-out test was executed, and the patterns of failure were assessed with microscopy. The data were analyzed using two-way ANOVA followed by Tukey’s test. The control group exhibited greater bond strength compared to the eucalyptol group in the cervical and middle thirds of the root (P < 0.05); however, it did not differ significantly from the xylene and orange oil groups (P > 0.05). No difference was observed in the values of the xylene, orange oil, and eucalyptol groups (P > 0.05). The cervical third had higher values than the apical third for all tested solvents (P < 0.05). Adhesive failure between resin cement and dentin was the most frequent type of failure. The use of xylene and orange oil as gutta-percha solvents did not influence the bond strength of fiberglass posts to root canal dentin. (J Oral Sci 56, 105-112, 2014)

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We assessed the stability of orthodontic mini-implants in young rats. Male rats with mean ages of 6 weeks (n = 16) and 20 weeks (n = 16) were divided into four groups (n = 8 each). In the 6- and 20-week immediate-loading groups, immediately after placement, mini-implants were exposed to an experimental traction force for 2 weeks. In the 6- and 20-week healing groups, the force was applied for 2 weeks after a 6-week healing period. Right tibiae served as the test limbs and the left tibiae as controls. A Periotest device was used to measure mini-implant mobility after traction, and Tukey’s test was used to compare Periotest values among groups. The results showed significantly greater mobility in the 6-week immediate-loading group than in the 20-week immediate-loading and 6- and 20-week healing groups, and significantly less mobility in the 6-week healing group than in the 20-week immediate-loading group (P < 0.05). Mini-implants were stable during the healing period. The results indicate that mini-implants can be used for orthodontic anchorage in juvenile patients if the duration of healing is sufficient. (J Oral Sci 56, 113-118, 2014)

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Chitosan, a multipurpose biomaterial, has been shown to exert effects against several types of cancer including oral cancer. However, the mechanisms underlying the anticancer activities of chitosan on oral squamous cell carcinoma (SCC) cells remain largely unknown. The present study aimed to compare the effects of low-molecular-weight chitosan (LMWC) and cisplatin on oral SCC Ca9-22 and non-cancer keratinocyte HaCaT cell lines. Cell viability and cell cycle profiles were measured by MTT assay and laser scanning cytometry, respectively. Apoptosis was examined by TUNEL assay and electron microscopy, followed by analysis of caspase activity. LMWC exhibited cytotoxic effects on Ca9-22, but not HaCaT cells, whereas cisplatin induced apoptosis in both types of cells. Exposure of Ca9-22 cells to LMWC led to G1/S cell cycle arrest and an increase of TUNEL-positive cells accompanied by an early apoptotic cell morphology and subtle increases of caspase activity. Short-term LMWC exposure was less cytotoxic to HaCaT cells than to Ca9-22 cells, and anticancer activity was exerted through induction of apoptosis and cell cycle arrest, suggesting that LMWC could be a promising natural anticancer agent with fewer side effects on normal cells. (J Oral Sci 56, 119-126, 2014)

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We investigated the prevalence of temporomandibular disorder (TMD) and its association with anxiety and depression among 1,493 Portuguese college students (age 17-69 years) at Piaget Institute. The assessment instruments were the Fonseca Anamnestic Questionnaire and the Hospital Anxiety and Depression Scale. TMD was present in 633 (42.4%) students, and anxiety or depression was present in 456 (30.5%) students. Regarding the association of TMD with anxiety and depression, 280 of the 633 students (61.4%) with TMD symptoms also had signs of anxiety or depression (P < 0.001). As compared with men, women had an odds ratio of 1.9 (95% confidence interval: 1.53-2.46; P < 0.001) for TMD. As compared with students without signs of anxiety or depression, students with such signs had an odds ratio of 3.1 (95% confidence interval: 2.42-3.84; P < 0.001) for TMD. College students from various fields of study and regions of Portugal had a high prevalence of TMD, which was significantly associated with anxiety and depression. (J Oral Sci 56, 127-133, 2014)

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Lipid peroxidation induced by reactive oxygen species (ROS) is involved in the pathogenesis of malignancy. Overall, lipid peroxidation levels are indicated by malondialdehyde (MDA), which is the most frequently used biomarker to detect oxidative changes. Antioxidant defense systems such as glutathione (GSH) limit cell injury induced by ROS. Therefore, MDA and GSH can be used to monitor oxidative stress (OS). Hence, this study aimed to evaluate and compare both salivary and serum levels of MDA and GSH in oral leukoplakia and oral squamous cell carcinoma (OSCC) patients, and healthy controls. The study included 100 subjects comprising 30 apparently healthy controls, 30 patients with oral leukoplakia and 40 clinically and histologically diagnosed patients with OSCC. Saliva and blood samples were obtained and evaluated for MDA and GSH. The study revealed enhanced MDA levels in saliva and serum in oral leukoplakia and OSCC patients as compared to controls. On the other hand, significant decreases were seen in serum and salivary GSH levels in oral leukoplakia and OSCC patients as compared to controls. Augmentation of OS in blood and saliva is reflected by increase in MDA and decrease in GSH levels, indicating that tumor processes cause an imbalance of oxidant-antioxidant status in cell structures. (J Oral Sci 56, 135-142, 2014)

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We investigated the effects of clinical characteristics and the interval between maintenance visits on incidence of peri-implant pathology in a sample of 1,350 patients treated with dental implants (270 cases of peri-implant pathology and 1,080 healthy controls). The chi-square test was used to evaluate differences between cases and controls in the presence of dental plaque, bleeding, peri-implant pockets >4 mm, bone level, and interval between maintenance visits (significance level, 5%). Crude odds ratios (ORs) and attributable fractions were calculated for variables that significantly differed between cases and controls. The variables identified as risk indicators were dental plaque (P < 0.001; OR = 5.2), bleeding (P < 0.001; OR = 5.0), peri-implant pockets >4 mm (P < 0.001; OR = 17.2), bone level (P < 0.001; middle third, OR = 8.4; apical third, OR = 8.6), and interval between maintenance visits (P < 0.001; 1-3 months, OR = 2.9; 3-5 months, OR = 2.1). Attributable fractions revealed a potential reduction in peri-implant pathology of 53-94% after removing exposures to dental plaque (81%), bleeding (80%), peri-implant pockets >4 mm (94%), bone level (88%), and interval between maintenance visits (53-66%). Selected clinical characteristics and the interval between maintenance visits were significantly associated with the incidence of peri-implant pathology. (J Oral Sci 56, 143-150, 2014)

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We evaluated whether a visual analog scale (VAS) was comparable to the multi-item Modified Dental Anxiety Scale (MDAS) in assessing dental anxiety in clinical practice. In total, 200 consecutive patients aged 20-70 years who presented at the dental outpatient department of SRM Dental College, Chennai were enrolled. The test-retest value for the VAS was 0.968. The Spearman rank correlations between the VAS and MDAS items and total score were significant (P < 0.001). The Spearman rank correlation between postponement of a dental visit and the VAS also showed a strong correlation (r = 0.473, P < 0.001). On linear regression analysis, the coefficient of determination showed a strong relationship between the two variables; the MDAS accounted for 74% of the variation. The regression coefficient was statistically significant (P < 0.001). On the basis of receiver-operating-characteristic curve analysis, a VAS cut-off value of ≥4.8 was selected to discriminate between patients who were and were not anxious, and a cut-off value of ≥7 was selected to identify patients with dental phobia. The weighted kappa was 69% for agreement between MDAS and the VAS in identifying patients with and without dental anxiety at cut-offs of 13 and 4.75, respectively. The VAS was found to be a valid measure and was comparable to the multi-item MDAS. (J Oral Sci 56, 151-156, 2014)

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MicroRNAs (miRNAs) are small non-coding RNAs showing a tissue-specific expression pattern, and whose function is to suppress protein synthesis. In this study, we hypothesized that expression of miRNAs would differ among fibroblasts from dental pulp (DPF), gingiva (GF) and periodontal ligament (PLF) in vitro. Once established by an explant technique, DPF, GF and PLF were collected for RNA isolation and subjected to a miRNA microarray. Next, cells were stimulated with E. coli lipopolysaccharide (LPS) for 24 h and then collected for RNA isolation. Expression of miR-146a and miR-155 was investigated by qPCR. Microarray screening revealed several miRNAs that showed specifically high expression in at least one of the fibroblast subtypes. These molecules are potentially involved in the regulation of extracellular matrix turnover and production of inflammatory mediators. Microarray analysis showed that both miR-146a and miR-155 were among the miRNAs expressed exclusively in GF. qPCR demonstrated significant upregulation of miR-146a only in GF after LPS stimulation, whereas basal expression of miR-155 was higher in GF than in the other cell subtypes. LPS downregulated the expression of miR-155 only in GF. Our results suggest that the expression and regulation of miR-146a and miR-155 are more pronounced in GF than in DPF and PLF. (J Oral Sci 56, 157-164, 2014)

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Craniofacial morphology and asymmetry were compared before, during, and after puberty within and between patients with unilateral complete cleft lip and palate (UCCLP) and a non-cleft group. In the UCCLP group, the posterior cranial base and total cranial base were significantly shorter at all skeletal periods, the maxilla was significantly retruded and posteriorly rotated, and the mandible was significantly smaller and inferoposteriorly rotated. The angle between the nasal and mandibular plane and lower anterior facial height were significantly higher, and upper posterior facial height and total posterior height were significantly lower, in the UCCLP group. Except for an increase in the nasal cavity, no significant differences were detected in facial width. For all measurements, asymmetry on the horizontal plane was more significant than that on the vertical plane. Asymmetries in the UCCLP group were mostly detected during puberty. The UCCLP group had no distinctive mandibular asymmetry, as compared with the Class I group. In UCCLP patients, the cranial base, maxilla, and mandible were affected on the sagittal plane during all growth periods. However, horizontal asymmetries were mostly detected before and during puberty. Vertical asymmetries were less severe, and there was no distinctive mandibular asymmetry as compared with the Class I group. (J Oral Sci 56, 165-172, 2014)

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Oral submucous fibrosis (OSMF) is a chronic fibrotic disorder in which the degree of vascularity has always been a matter of dispute; however, morphological studies of the blood vessels in OSMF have been sparse. This study was performed to assess the mucosal vasculature in normal oral mucosa, early and advanced OSMF, and well differentiated squamous cell carcinoma (WDSCC) using morphometry. The study included histologically diagnosed cases of early (n = 30) and advanced (n = 30) OSMF, and WDSCC (n = 30), with normal oral mucosa (n = 10) as a control. Morphometric image analysis of blood vessels was performed on H&E-stained sections for evaluation of vascular density, vascular luminal diameter, area and percentage area. A significant increase in all of the parameters was noted in the test groups relative to the controls. The mean vascular density and mean vascular percentage area were significantly increased in early OSMF and WDSCC relative to controls, and also in advanced OSMF and WDSCC in comparison with early OSMF. The vascularity increased progressively from normal to premalignancy and malignancy, emphasizing the importance of angiogenesis in tumor development and progression. The vascularity was increased in early OSMF and reduced in advanced OSMF, suggesting that inflammation may play a role in the early stages while progressive fibrosis may predispose to atrophy of the epithelium and subsequent malignant changes. (J Oral Sci 56, 173-178, 2014)

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Studies are needed to determine the prognosis of different forms of dental prosthetic rehabilitation and the main complications involved. The purpose of the present study was to evaluate technical complications involving implant-supported prostheses. A retrospective one time snap-shot study was carried out with a total of 509 implants in 153 patients. Prosthetic conditions were determined by clinical and radiographic examination. The least frequent technical complication involved fracture (0.2%), loss (0.4%) and loosening (3.3%) of the screw. The most frequent complications were loss of resin covering the screw (23.8%), loss of overdenture retention (18.6%) and fractures of the resin (12.4%). A high frequency of misfit between the prosthesis and abutment (25.4%) was found, which was significantly associated (P < 0.05) with other variables, especially cemented prostheses (P < 0.001). To minimize the frequency of complications, protocols must be established from diagnosis to the completion of treatment and follow up of implant-supported prostheses, especially in terms of adequate technical steps and careful radiographic evaluation of the components. (J Oral Sci 56, 179-184, 2014)

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