Silane coupling agents alter the properties of material surfaces, which are modified by means of an organic functional group of specific silanes. This review describes the use of hydrophobic silane compounds for surface modification of silica-based and other materials. (J Oral Sci 58, 151-155, 2016)

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We investigated the short-term (4 weeks) color stability of light-cure and dual-cure resin cements. Sixty disk-shaped test specimens of adhesive resin cement (10 × 1 mm) were prepared. One feldspathic porcelain test specimen (12 × 14 × 0.8 mm) was prepared from a prefabricated ceramic block. The feldspathic sample was placed on the resin cement disk and all the measurements were performed without cementation. Specific color coordinate differences (ΔL, Δa, and Δb), and the total color differences (ΔE) were calculated after immersion in distilled water for different periods. Data were compared using one-way analysis of variance (ANOVA) (α = 0.05). The test results revealed that different chemical structures and curing modes affected the ΔE values (P < 0.05). The highest ΔE values were obtained for RelyX Unicem dual-cure cement (2.14 ± 0.40), and the lowest for NX3 light-cure cement (0.78 ± 0.34). Third generation adhesive resin cement free of tertiary amines and benzoyl peroxide showed relatively slight color change in both test groups (light-cure and dual-cure resin cement). (J Oral Sci 58, 157-161, 2016)

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Porphyromonas gingivalis is important in the development of marginal periodontitis. However, the precise role and localization of P. gingivalis in chronic periapical periodontitis remain unclear. Thus, methods that can detect P. gingivalis in formalin-fixed and paraffin-embedded (FFPE) tissue samples are needed. We assessed a technique combining loop-mediated isothermal amplification (LAMP) with PCR (PCR-LAMP) for detection of P. gingivalis, using 110 FFPE tissue samples of chronic apical periodontitis. PCR-LAMP specifically detected P. gingivalis with high sensitivity in FFPE tissue samples, and the sensitivity of the technique was higher than that of PCR or LAMP alone. The results of immunohistochemistry (IHC) confirmed the specificity of PCR-LAMP. IHC showed that P. gingivalis was localized in a granular layer of chronic apical periodontitis, a region that correlated with the localization of macrophages. This is the first study to describe the localization of P. gingivalis in human periapical periodontitis. In conclusion, PCR-LAMP was an effective tool for detecting P. gingivalis in periapical periodontitis. In addition, IHC results improve our understanding of the role of P. gingivalis in the progression of periapical periodontitis. (J Oral Sci 58, 163-169, 2016)

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This study was conducted to investigate the association between symmetrical agenesis of the mandibular third molars and agenesis of other teeth in Japanese orthodontic patients. A sample of 64 patients with symmetrical agenesis of the mandibular third molars and without agenesis of the maxillary third molars was selected as the third molar agenesis group. In addition, 585 patients with all 4 third molars were selected as controls. The main materials examined for diagnosis of tooth agenesis were panoramic radiographs. The prevalence rate of tooth agenesis was compared between the groups using the chi-squared or Fisher’s test, and the odds ratio. Significantly increased occurrence of overall agenesis of the maxillary lateral incisors, and overall and symmetrical agenesis of other teeth including the maxillary and mandibular second premolars and mandibular first molars were observed in the patients with symmetrical agenesis of the mandibular third molars and without agenesis of the maxillary third molars. Irrespective of the presence or absence of symmetrical agenesis of the mandibular third molars, no significant differences in the prevalence rates of overall or symmetrical agenesis of other teeth and specific teeth were noted between the sexes or between the right and left sides of the jaws in the patients without maxillary third molar agenesis. (J Oral Sci 58, 171-176, 2016)

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We examined the short-term surgical effects of orthognathic surgery on somatosensory function. Observations were made over a short period: 3 months postoperatively. In total, 14 patients and 32 healthy controls participated. Among the 14 patients, one underwent bilateral sagittal split osteotomy alone and 13 underwent bilateral sagittal split osteotomy in combination with a Le Fort I osteotomy. A modified quantitative sensory testing (QST) protocol (the German Research Network on Neuropathic Pain, DFNS) was used to evaluate clinically the skin of the chin for sensory disturbances before surgery and at 1 week, 1 month, and 3 months postoperatively. A visual analog scale and the Japanese Version of the McGill Pain Questionnaire were completed by all participants. Both sides of the mandible showed postoperative functional loss in cold detection threshold, warmth detection threshold, thermal sensory limen, and mechanical detection threshold. All function gradually recovered to baseline conditions at 3 months postoperatively. Cold detection threshold, warmth detection threshold, thermal sensory limen, and mechanical detection threshold appeared to be useful QST parameters for evaluating neurosensory disturbances during the early postoperative period. (J Oral Sci 58, 177-184, 2016)

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The aim of this study was to evaluate changes in jaw bones due to osteoporosis using cone beam computed tomography (CBCT) images. Subjects that had undergone CBCT for various oral conditions and demonstrating clinical findings of osteoporosis were invited to participate in the study. Dual X-ray absorptiometry (DXA) was performed on 90 patients aged over 30 years who underwent CBCT. The study groups were based on DXA results, and included 26 osteoporosis patients (mean age ± standard deviation; 58.52 ± 5.91), 33 osteopenia patients (52.67 ± 8.61) and 31 healthy controls (49.81 ± 10.47). CBCT images of jaw bones were evaluated using radiomorphometric indexes, CT values, histogram analysis (HA) and fractal dimension (FD) analysis. Right and left mandibular radiomorphometric indexes, CT values and HA measurements in osteoporosis patients were significantly lower than measurements in osteopenia patients and control subjects (P ≤ 0.05). Positive correlations were observed between measurements of spine bone mineral density (BMD) and right and left mandibular CT values (P ≤ 0.01) and HA (P ≤ 0.01) measurements. Left maxilla FD measurements in osteoporosis patients were significantly lower than in the control (P ≤ 0.05) and osteopenia (P ≤ 0.05) groups. Osteoporosis caused significant changes in radiomorphometric indexes, CT values, and HA and FD measurements in the jaw bones. (J Oral Sci 58, 185-194, 2016)

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We investigated the temporal association between temporomandibular disorders (TMD)-related symptoms and headache during TMD treatment for patients who fulfilled the diagnostic criteria for headache attributed to TMD (HATMD) specified in the Diagnostic criteria for TMD (DC/TMD) and International classification of headache disorders (ICHD)-3 beta. The study enrolled 34 patients with HATMD induced by masticatory myofascial pain but not by temporomandibular arthralgia. Facial pain intensity, the pressure pain threshold of pericranial muscles, and maximum unassisted opening of the jaw were assessed at an initial examination and before and after physical therapy. The intensity and frequency of headache episodes and tooth contact ratio were also recorded before and after the intervention. Headache intensity and frequency significantly decreased, and these reductions were temporally related to improvements in facial pain intensity, maximum unassisted opening, and pressure pain threshold during TMD treatment. Linear regression analysis showed significant correlations between facial pain intensity and headache intensity and between tooth contact ratio and pressure pain threshold. Among patients who fulfilled the DC/TMD and ICHD-3 beta diagnostic criteria for HATMD, headache improved during TMD treatment, and the improvement was temporally related to amelioration of TMD symptoms. These findings suggest that sensitization in the central and peripheral nervous systems is responsible for HATMD. (J Oral Sci 58, 195-204, 2016)

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We examined the use of surgical eye spears for saliva collection and recovery of secretory immunoglobulin A (s-IgA). We established a protocol for recovering s-IgA at concentrations equivalent to those present in the control samples (untreated by surgical eye spears). Four different types of eye spears were submerged in the salivary fluid. Saliva was recovered from each spear by centrifugation. Novel ultra-sensitive enzyme-linked immunosorbent assay was used to determine s-IgA concentration in each sample. The results revealed that Weck-Cel eye spears recovered s-IgA at concentrations not significantly different from s-IgA concentrations in control samples as long as the appropriate protocol was followed. We demonstrated that the use of surgical eye spears for saliva collection is a viable method for recovering s-IgA. (J Oral Sci 58, 205-210, 2016)

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We evaluated the cytotoxic effects of the debris apically extruded during root canal retreatment on primary human osteoblast (HOb) cells in vitro. TNF-α and IL-1β levels were also measured. We examined three different techniques: conventional hand-files, and Mtwo and Reciproc retreatments. Filled mandibular incisors were prepared for a cytotoxicity assay in an experimental root model. The material was divided into three groups according to the technique used. Ten teeth were used as control. HOb cells were exposed to the extruded content and cytotoxicity was evaluated using the MTT test (assessing cell metabolic activity). TNF-α and IL-1β production was also analyzed using enzyme-linked immunosorbent assay. Then, all the teeth were radiographed and the residual filling material was quantified. Data were subjected to analysis of variance (ANOVA) and Tukey’s test (P < 0.05). The conventional hand-file technique was significantly more cytotoxic than the other methods (P < 0.05). Reciproc was less cytotoxic than Mtwo retreatment (P < 0.05). All endodontic retreatment techniques led to a significant upregulation of IL-1β levels (P < 0.05). However, only the conventional hand-file technique caused a significant increase in TNF-α levels (P < 0.05). Root-filling removal did not affect the levels of these proteins (P > 0.05). The Reciproc system required less time than the other two methods to remove the root-filling materials (P < 0.01). The endodontic retreatment with Reciproc was the least cytotoxic and the least time-consuming method of gutta-percha and sealer removal. (J Oral Sci 58, 211-217, 2016)

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Skeletal myogenesis is regulated by a considerable number of microRNAs (miRNAs). miRNA regulatory networks are complicated, and details of how they operate remain unclear. In this study, MTT assays confirmed that miR-29a is the most effective miR-29 paralog. Microarray analysis demonstrated upregulation of ten-eleven translocation enzyme-1 (Tet1) mRNA in response to miR-29a inhibition in C2C12 murine myoblast cells. We investigated the factors acting downstream in the miR-29a-Tet1 signal pathway using real-time RT-PCR. MyoD expression was upregulated by Tet1 inhibition and downregulated by miR-29a inhibition, whereas expression of cyclin-dependent kinase 6 (Cdk6) was regulated in an opposite manner. These results suggest that the miR-29a-Tet1 pathway upregulates MyoD expression and conversely downregulates Cdk6 expression. However, changes in the expression of other myogenic factors such as serum response factor (Srf), the myocyte enhancer factor 2 family (Mef2a, b and c), myogenin, myogenic regulatory factor 4 (Mrf4), muscle creatine kinase (Mck), and other cell cycle regulators such as Cdk4 and thymine DNA glycosylase (Tdg) cannot be explained in terms of the miR-29a-Tet1 pathway alone. The miR29a-Tet1 pathway may be part of a complex myogenic regulatory network in C2C12 cells. (J Oral Sci 58, 219-229, 2016)

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We investigated the effects of proximity of the root apex to the maxillary labial cortical plate, palatal cortical plate, and incisive canal cortical plate on apical root resorption. Cone-beam computed tomography was used to measure the amount of root resorption and root apex movement around maxillary right and left central incisors in 30 adults who underwent four-bicuspid extraction followed by treatment with multibracket appliances. The patients were divided into three groups on the basis of the direction of root apex movement, after which the correlation between the amount of root resorption and root apex movement was determined. Mean apical root resorption was 1.80 ± 0.82 mm (range, 0.18-3.96 mm). The amount of root apex movement was positively correlated with the amount of root resorption on the side of pressure. Root apex proximity to the maxillary labial cortical plate, palatal cortical plate, and incisive canal cortical plate was associated with apical root resorption. Orthodontic treatment plans should carefully consider root proximity to the maxillary cortical plate. (J Oral Sci 58, 231-236, 2016)

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This study aimed to examine the role of stress in the occurrence of recurrent aphthous stomatitis (RAS) and oral lichen planus (OLP), as well as to analyze the efficacy of saliva, urine, and serum cortisol levels as markers of stress. This study included 30 subjects with RAS (Group A), 30 with OLP (Group B), and 30 controls (Group C). The serum, salivary, and urinary cortisol levels were measured using electro-chemiluminescence immunoassay. The results were analyzed using the independent t-test, and a statistically significant difference (P = 0.000) was observed between the study and control groups. Further analysis was done using ANOVA and post-hoc tests. The results of this study suggest that RAS and OLP patients had higher cortisol levels than controls, indicating that stress acts as a co-factor in the pathogenesis of RAS and OLP. Although urinary cortisol level was found to be the best indicator of stress, saliva can also be used as a reliable marker. (J Oral Sci 58, 237-240, 2016)

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The aim of the study was to investigate the effect of parathyroid hormone (PTH) on primary stability of dental implants in a bone-reduced model. Ten female New Zealand white rabbits underwent ovariectomy and were administered glucocorticoid to induce osteoporosis. One group was administered PTH intermittently by subcutaneous injection for 4 weeks (PTH-group) and the other group was given injections of saline for 4 weeks (Osteoporosis; OP-group). After the administration period, implants were inserted into the distal femoral epiphyses of each animal. At implant placement, insertion torque (IT) and implant stability quotient (ISQ) were measured. Histological examination revealed newly formed trabecular bone around the implant socket in the PTH-group but not in the OP-group. The trabecular bone structures in the PTH-group appeared thicker than those in the OP-group. In the PTH-group, the mean IT value was significantly greater than that in the OP-group (29.8 ± 6.2 Ncm and 10.0 ± 2.1 Ncm, respectively; P < 0.05). The ISQ value in the PTH-group was significantly higher than that in the OP-group (74.7 ± 11.2 and 55.9 ± 13.5, respectively; P < 0.05). Intermittent PTH administration could be an effective treatment for achieving favorable primary stability of dental implants in patients with osteoporosis. (J Oral Sci 58, 241-246, 2016)

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About 30% of male infertility cases are idiopathic. Previous studies reported a positive correlation between deep periodontal pockets and sperm sub-motility, which suggests that periodontitis might have a role in idiopathic semen abnormality pathospermia. We evaluated correlations between periodontal infection parameters and the results of sperm analysis of men with idiopathic infertility. In this observational study, semen quality and periodontal status were analyzed for 95 otherwise healthy men attending an andrology unit for sperm analysis. Half the men in the sperm pathology and normozoospermia groups (50.8% and 50%, respectively) had poor periodontal status. Among the 95 participants, 38% had oligozoospermia, 28% had asthenozoospermia, 16% had cryptozoospermia, and 15% were classified as normozoospermic. Sperm pathology category was not associated with frequency of deep periodontal pockets or calculus. Bleeding on probing was significantly lower among men with asthenozoospermia than among those with normozoospermia. Poor periodontal status was not associated with any sperm pathology category or parameter. In contrast with previous findings, the present results indicate that pathospermia and poor semen quality are not associated with periodontal infection in men with idiopathic infertility. (J Oral Sci 58, 247-253, 2016)

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The formation of cross-linkages between and within collagen is catalyzed by lysyl oxidase, which can be inhibited by β-aminopropionitrile (BAPN), a lathyrogen from sweet pea (Lathyrus odoratus) seeds. The quality and integrity of the collagenous template of skeletal elements depend on an appropriate concentration of collagen cross-links. In this study, chick embryos treated in ovo with BAPN on embryonic days (ED) 4-9 were found to develop multiple skeletal deformities. The most readily discernible and highly reproducible deformity was evident in the tibiotarsus, on which we focused to explore the chronology of the malformation process. Several lines of observation indicated that the bending deformity observable at ED10 in the tibiotarsus was inducible by BAPN administered on ED4-8; in other words, administration of BAPN on ED8 was sufficient to induce the deformity by ED10, whereas administration on ED9 was ineffective. Ultrastructurally, osteoclasts appeared to show enhanced activity in the medullary surface of the bone collar after BAPN administration. In addition, bone hyperplasia associated with the bending deformity was suggested to be correlated with higher osteoblast activity on the concave (or flexor) side of the tibiotarsal skeleton. These findings indicate that the bending deformity due to reduced mechanical integrity of the collagenous template is also associated with aberrant bone remodeling. (J Oral Sci 58, 255-263, 2016)

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Our objective was to compare archived tissue biopsy samples from the oral cavity and oropharynx, in terms of human papillomavirus (HPV) 16 infection. We used Taqman real-time PCR assay to detect HPV16 in 121 archived biopsy samples from the oral cavity and 100 samples from the oropharynx. Among patients with oral cavity cancer (OCC), 9% (6/65) had HPV16 infection which was significantly less than those with oropharyngeal cancer (OPC) where 79% (39/50) were HPV16 positive (P < 0.001). Our results demonstrated a significant difference between genders where males had a seven times higher chance of having HPV16 infection (P < 0.001). Viral load variation between each group was demonstrated. The median viral load in OPC was similar in OCC cases, but cancer samples were significantly higher than in non-cancer cases (oral cavity samples P = 0.015; oropharynx samples P = 0.09). From our results, we conclude that there is a significant difference in HPV16 detection between OCC and OPC, and HPV16 differs greatly between male and female cancer patients. (J Oral Sci 58, 265-269, 2016)

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We explored the effects of sclerostin removal in vivo on experimental periodontitis in mice. A ligature of Porphyromonas gingivalis-saturated collagen silk was applied to the cervical region of the first molar tooth in 10 wild-type (WT) mice and 10 sclerostin-knockout (SOST-KO) mice, and the animals were fed 10% sucrose for 2 months. Another 10 WT mice and 10 SOST-KO mice were similarly treated, but then fed a normal diet for 2 months. The maxillae were then harvested for morphological and molecular examinations. The mice with periodontitis showed significantly more severe alveolar bone loss than control mice, the most significant absorption being observed in WT mice. Immunohistochemical staining demonstrated upregulation of RANKL and ERK1/2-MAPK expression and downregulation of OPG expression in mice with periodontitis, especially WT mice. Therefore, removal of sclerostin appears to modestly protect the alveolar bone from resorption in this experimental setting. (J Oral Sci 58, 271-276, 2016)

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To develop a root canal filling material with high antimicrobial activity, we prepared gutta-percha supplemented with the cationic surfactant cetylpyridinium chloride (CPC). Thermoplastic gutta-percha was supplemented with 0.05%, 0.2%, or 0.8% CPC. The gutta-percha containing CPC was tightly packed at the bottom of a 24-well plate. Its antimicrobial activity against eight representative endodontic pathogens-including gram-positive and gram-negative bacteria and fungi-was evaluated by adding 0.5 mL of liquid samples containing pathogens to the wells. After 24 h of cultivation under appropriate conditions, microbial growth was analyzed by counting colony-forming units (CFU). Gutta-percha alone (without CPC) partially inhibited microbial growth, probably through the antimicrobial effect of some of its components, such as zinc oxide. Addition of CPC dose-dependently increased the antimicrobial efficacy of gutta-percha. Addition of 0.05%, 0.2%, and 0.8% CPC reduced the viable microbial number to below the lower limit of detection (20 CFU/mL) for all tested pathogens except Pseudomonas aeruginosa, which was detected in 0.8% CPC-containing gutta-percha, although the viable number significantly decreased. Gutta-percha with CPC might be useful for preventing microbial infections during root canal therapy. (J Oral Sci 58, 277-282, 2016)

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Notch signaling dysregulation plays an important role in altering cancer cell behaviors; however, its role in oral squamous cell carcinoma (OSCC) remains controversial. This study aimed to investigate the role of Notch signaling related genes in human OSCC using a meta-analysis of Gene Expression Omnibus database (GEO-publicly available gene expression microarray data) and to examine the role of Notch signaling in OSCC behaviors. The meta-analysis included 13 GEO datasets and was performed by combining effect sizes in a random effect model. The results demonstrated that in OSCC dysregulated genes participated in the metabolic process and protein binding as determined by gene ontology analysis. Enriched pathway analysis demonstrated the majority of the dysregulated genes were involved in pathway categories as follow; pathway in cancers, small cell lung cancer, extracellular matrix-receptor interaction, focal adhesion, and cell cycle progression. Interestingly, the enriched pathway analysis also demonstrated that OSCC samples exhibited an upregulation of genes in Notch signaling pathway, namely JAG1, JAG2, ADAM17, NCSTN, PSEN1, NCOR2, NUMB, DVL3, HDAC1, and HDAC2. Furthermore, Notch signaling inhibition by a γ-secretase inhibitor significantly decreased OSCC cell proliferation in vitro, corresponding with a decrease in C-FOS mRNA expression. The study demonstrated that Notch signaling is dysregulated in human OSCC and plays a role in cell proliferation. (J Oral Sci 58, 283-294, 2016)

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Dens invaginatus (DI) is a dental anomaly exhibiting complex anatomical forms. Because of this anatomical complexity, immature DI teeth with necrotic pulp are difficult to treat via apexification. We used revascularization as an alternative treatment for a patient with DI. An 11-year-old boy visited our clinic with chief complaints of gingival swelling and pain in the left maxillary canine. Clinical and radiographic findings were consistent with a diagnosis of type III DI. Revascularization therapy was performed, and a 24-month follow-up examination confirmed healing of the periapical radiolucency and physiological root formation. (J Oral Sci 58, 295-298, 2016)

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