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Carlos A. Jurado, Akimasa Tsujimoto, Amit Punj, Natsuko Aida, Masashi Miyazaki, Hidehiko Watanabe
Journal of Oral Science, Volume 63, pp 358-360; https://doi.org/10.2334/josnusd.21-0070

Abstract:
Introducing new technology in the dental school curriculum may face some uphill challenges navigating through university-level bureaucracy, financial ramifications, and influencing the mindset of certain faculty. A dental school that relies heavily on teaching traditional restorative procedures may particularly face many challenges to embrace new technology. The restorative department at a US dental school created a division of computer-aided design and computer-aided manufacturing (CAD/CAM) dentistry to introduce the concept of digital dentistry to dental students and faculty. This article describes methods that were adopted to improve acceptance and increase the productivity of chairside CAD/CAM restorations for both students and faculty at the dental school in US.
David Colmenar, Tenzin Tamula, Qiang Zhu, Chul Ahn, Carolyn Primus, Takashi Komabayashi
Journal of Oral Science, Volume 63, pp 306-309; https://doi.org/10.2334/josnusd.21-0196

Abstract:
Purpose: This study compared the removability of AH Plus and EndoSequence BC sealers using in vitro micro-computed tomography. Methods: Ten single-canal, extracted human teeth were cleaned and shaped with ProTaper NEXT rotary files to size X5 (50/0.06) (Dentsply-Sirona). Canals were obturated with a single cone gutta-percha and either AH Plus (Dentsply-Sirona) (Group A) or EndoSequence BC (Brasseler) (Group B). ProTaper Universal Retreatment files (Dentsply-Sirona) were used to remove obturation materials after 90 days at 37oC/100% humidity. Each tooth was scanned using micro-computed tomography (SkyScan 1272; Bruker) at an isotropic resolution of 6 μm from which the percent of material removed was calculated. Two-sample t-tests and one-way ANOVA were used for analysis. Results: The percent removal of materials in the coronal third was 92.9% ± 7.3% (Group A) and 93.2% ± 6.1% (Group B). Removal in the middle third was 94.9% ± 8.5% (Group A) and 96.5% ± 6.1% (Group B). Apical third removal was 76.2% ± 27.9% (Group A) and 70.1% ± 30.8% (Group B). No statistically significant differences were determined between the two sealers or among the sectional thirds within each group (P > 0.05). Conclusion: AH Plus and EndoSequence BC sealers exhibit the same removability at all canal levels of 70% to 96%, with better removal coronally.
Noel Ye Naung, Warwick J Duncan, Rohana K. De Silva, Dawn E. Coates
Journal of Oral Science, Volume 63, pp 341-346; https://doi.org/10.2334/josnusd.21-0164

Abstract:
Purpose: This study aimed to determine expressions of hepatocyte growth factor (HGF) and MET proto-oncogene receptor tyrosine kinase (MET) in palatal periosteum (PP) and to examine the effect of HGF/MET on osteogenic differentiation of human palatal periosteum-derived mesenchymal stem cells (PD-MSCs). Methods: HGF/MET proteins in human palatal periosteum (n = 3) were localized using immunohistochemistry. PD-MSCs (n = 3) were cultured in serum-free Essential 8 (E8) medium or osteogenic medium with and without Capmatinib, a selective ATP-inhibitor of MET. HGF concentration in vitro was measured with ELISA. Relative gene expression was quantified from PD-MSCs by quantitative reverse transcription real-time polymerase chain reaction. Results: Immunohistochemistry detected co-localization of HGF and MET protein in PP. HGF protein levels were significantly higher (P < 0.05) in osteogenic media (day 21: 12.19 ± 8.36 ng/mL) than in E8 medium (day 21: 0.42 ± 0.72 ng/mL). MET inhibitor had a limited feedback effect on the expression profile of the osteogenic genes tested. Gene expression levels for all but three genes were comparable in serum-free and osteogenic media at all time points. Conclusion: HGF/MET present in human PP and HGF is upregulated in vitro during osteogenesis; however the targeted pathways controlled by MET may not involve osteoblast maturation.
Hanadi Y. Marghalani
Journal of Oral Science, Volume 63, pp 31-36; https://doi.org/10.2334/josnusd.20-0082

Abstract:
Purpose: This study evaluated the flexural strength of bulk-fills after immersion in food-simulating solvents. Methods: Four overlapping segments along both sides of bar-shaped specimens (25 × 2 × 2 mm) made from bulk-fill composite were irradiated with an Elipar LED light-curing (1,200 mW/cm2 for 20 s) device. The specimens were then divided into four groups (n = 20), according to storage media—namely, distilled water, 99% ethanol, heptane, and methyl ethyl ketone—at 37oC for 4 weeks. Flexural testing was done with a universal testing machine at a crosshead speed of 1 mm/min. Results: Data were analyzed with the two-way and one-way ANOVA and post-hoc Tukey (HSD) tests (P < 0.05), along with the Weibull statistic. Flexural properties significantly differed in relation to the bulk-fill and solvent used. The flexural properties of bulk-fills decreased in solvents. SonicFill in distilled water had the highest values for flexural properties (σf = 165.77 MPa; Ef = 10.3 GPa), followed by the values for SonicFill in ethanol and those for X-tra base and everX Posterior in water. Venus Bulk Fill in methyl ethyl ketone yielded the lowest values (σf = 74.11 MPa; Ef = 3.06 GPa). Conclusion: The flexural properties of bulk-fills are affected by the food-simulating solvent used and by the filler content, type, and resin component.
Osamu Takahashi, Junpei Tanaka, Manabu Habu, Daigo Yoshiga, Masaaki Sasaguri, Masataka Uehara, Mana Hayakawa, Izumi Yoshioka, Kazuhiro Tominaga
Journal of Oral Science, Volume 63, pp 101-103; https://doi.org/10.2334/josnusd.19-0510

Abstract:
A simple sandwich technique using buttons to compress grafted tissue combined with a tie-over technique for intraoral split-thickness skin grafts (STSGs) is introduced. This technique yielded an excellent engraftment rate (90.5%) and no instances of total graft failure were recorded. This simple sandwich technique for STSGs is readily applicable and inexpensive, and the present results show that it would be potentially useful for repair of defects in the oral cavity.
Xiao-Mei Hou, Yin-Jie Yang, Jun Qian
Journal of Oral Science, Volume 63, pp 8-13; https://doi.org/10.2334/josnusd.19-0331

Abstract:
WaveOne Gold, ProTaper Gold, Reciproc Blue, ProTaper Next, WaveOne and ProTaper files were selected to compare the phase transformation behaviors and mechanical properties of nickel-titanium (NiTi) rotary files after gold heat and blue heat treatments. The reverse transformation finishing point temperatures of WaveOne Gold, ProTaper Gold, ProTaper Next and WaveOne were higher than those of the other two instruments investigated. At a deflection of 0.5 mm, the loads were significantly varied except for ProTaper Next and ProTaper Gold. At a deflection of 3.0 mm, the loads of Reciproc Blue and WaveOne Gold were significantly varied compared to WaveOne and ProTaper. Cycles to failure were reduced in the order of WaveOne Gold, Reciproc Blue, ProTaper Gold, ProTaper Next, WaveOne and ProTaper. NiTi instruments after gold heat and blue heat treatments exhibited significantly higher bending properties and cyclic fatigue resistances, representing an improved performance over traditional and M-wire instruments.
Veridiana Camilotti, Márcio J. Mendonça, Max Dobrovolski, Anna C. DeTogni, Gláucia M. B. Ambrosano, Mario F. De Goes
Journal of Oral Science, Volume 63, pp 18-21; https://doi.org/10.2334/josnusd.19-0518

Abstract:
This in vitro study was performed to evaluate the surface roughness (Ra) and morphology by scanning electron microscopy (SEM) of composite resins that had been stored in acidic solutions typical of those present in the diet. Three composite resins (4 Seasons, Z250, and P90) were selected and divided into three groups (n = 7) according to the solutions tested: G1: distilled water; G2, Coca-cola, and G3: orange juice. The Ra test was repeated after immersion periods of 15, 90, and 180 days. The mean Ra values were subjected to LS means analysis and the Tukey-Kramer (P < 0.05). One test specimen of each composite resin was selected for SEM analysis after each period. The Ra data indicated that P90 had the lowest Ra values. 4 Seasons and Z250 had statistically similar roughness values for all the solutions and evaluation periods. With the exception of 180-day immersion in Coca-cola, 4 Seasons showed significantly higher values than Z250. SEM analysis showed that P90 was the composite resin most resistant to the actions of all acid solutions for the periods analyzed. Interaction between components of the solutions and the active components of other dietary items, as well as oral hygiene, may affect the chemical degradation of composite resins.
Shinya Yamauchi, Satoshi Watanabe, Takashi Okiji
Journal of Oral Science, Volume 63, pp 65-69; https://doi.org/10.2334/josnusd.20-0325

Abstract:
The purpose of this study was to examine the effect of heating on the physical properties of four types of premixed calcium silicate-based root canal sealers. Endoseal MTA, Well-Root ST, EndoSequence BC Sealer, EndoSequence BC Sealer HiFlow, and AH Plus (epoxy resin root canal sealer) were heated at 100°C for 1 min, and changes in setting time, flow, and film thickness were evaluated in accordance with ISO 6876:2012 standards. In addition, pH measurement and scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses of the set materials were performed. All root canal sealers heated at 100°C showed significant decreases in setting time and flow, particularly Endoseal MTA. In addition, the film thickness of Endoseal MTA increased significantly after heating at 100°C. The pH and SEM/EDS results were not affected by heating. Heating calcium silicate-based root canal sealers accelerated setting time, decreased flow, and increased film thickness. However, the degree of these changes varied among the products. The present findings indicate that heat-induced changes in the physical properties of calcium silicate-based root canal sealers could adversely affect the quality of warm vertical condensation technique.
Noboru Noma, Yuki Watanabe, Akiko Shimada, Sho Usuda, Takashi Iida, Atsushi Shimada, Yuto Tanaka, Yuka Oono, Keiichi Sasaki
Journal of Oral Science, Volume 63, pp 4-7; https://doi.org/10.2334/josnusd.20-0437

Abstract:
Numerous studies have confirmed the effectiveness of cognitive behavioral therapy (CBT) for chronic pain, and it is generally regarded as an appropriate intervention. However, it may not be effective for some pain sites, and the duration of the effect may be limited. In addition, some studies of CBT lacked a comparison group. This review summarizes evidence for the effectiveness of CBT for orofacial pain and assists in the development of guidelines for orofacial pain management. A literature search in PubMed was performed for studies published from April 1990 through March 2020. The search keywords were “burning mouth syndrome,” “temporomandibular disorders,” “myofascial pain syndrome,”“chronic orofacial pain conditions,” “cognitive behavioral therapy,” and “non-pharmacological therapy.” The results indicate that CBT alone or in combination with other treatments, such as intraoral appliance, stress management, or biofeedback, is effective for the vast majority of orofacial pain cases. Therefore, dentists should consider using CBT to manage orofacial pain in their patients.
Jorge Chaurand, Marycarmen Godínez-Victoria, Aldo Tellez-Girón, Jose-Alfredo Facio-Umaña, Fiacro Jimenez-Ponce
Journal of Oral Science, Volume 63, pp 37-40; https://doi.org/10.2334/josnusd.20-0090

Abstract:
Purpose: This study assessed the effectiveness of incobotulinum toxin type A (IBTx) for chronic myofascial pain affecting the masseter and temporal muscles. Methods: Twenty two patients who received a diagnosis of chronic masseter and temporalis myofascial pain were evaluated by using a visual analog pain scale (VAS), digital pressure algometry, and the SF-36 Health Survey at baseline (T0), before IBTx injection. Patients were again evaluated at 2 months (T1) and 7 months (T2) after IBTx injection. Results: VAS scores for pain significantly differed (P = 0.029, Friedman test). Post-hoc tests showed a significant reduction in pain at 2 months (T0–T1) and 7 months (T0–T2) (P = 0.011 and P = 0.028, respectively; Wilcoxon test) but not between 2 and 7 months (P = 0.676; Wilcoxon test). There was no significant difference in pressure algometry values (P = 0.385, Friedman test). Quality of life (QOL) assessment showed a significant difference (P = 0.002, Friedman test). Post-hoc tests showed a significant improvement in QOLat 2 months, but no significant difference at 7 months (P = 0.004 and P = 0.260, Wilcoxon test). Conclusion: IBTx injection resulted in safe, effective short-term pain relief for patients with chronic facial pain affecting the masseter and temporalis muscles.
Sho Tanaka, Taku Toriumi, Tatsuaki Ito, Yuta Okuwa, Taku Futenma, Keita Otake, Yasunori Akiyama, Kenichi Kurita, Toru Nagao, Masaki Honda
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0611

Abstract:
Purpose: The aim of this study was to assess the response of dental pulp associated with donor or host cells in the pulp chamber and root canal after extra-oral transplantation. Methods: Wild type or green fluorescent protein (GFP) transgenic first molars from 3-week, 6-week, and 12-week mice were transplanted into the subcutaneous layer of GFP mice or wild type mice. The teeth were histologically and immunohistochemically examined at 5 weeks after transplantation. Results: Blood vessels present in the original coronal pulp had anastomosed with those from the recipient tissue that had invaded the root canal. Two distinct eosin-stained extracellular matrices were observed in the pulp chamber and root canal. Acellular matrix composed of nestin-positive, odontoblast-like cells invaded from the outside and was seen in the root canal of 3-week teeth. Cellular matrix comprising alkaline phosphatase (ALP)-positive fibroblast-like cells appeared in the original coronal pulp. In the root canal of the 6-week and 12-week teeth, cellular extracellular matrix consisting of ALP-positive fibroblast-like cells had invaded the recipient tissue. Conclusion: Dental pulp from immature teeth might be able to regenerate dentin-like tissue. This model could be useful in the development of an optimized vitalization treatment.
Tadashi Masaoka, Keiji Shinozuka, Kenshin Ohara, Hiromasa Tsuda, Kenichi Imai, Morio Tonogi
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0662

Abstract:
Purpose: The present study aimed to identify dysregulated exosomal miRNAs associated with diagnostic and therapeutic biomarkers in oral squamous cell carcinoma (OSCC). Methods: Microarray analysis was used to compare expression profiles of exosomal miRNAs in the OSCC-derived cell lines HSC-2, HSC-3, Ca9-22, and HO-1-N1 with those in human normal keratinocytes (HNOKs). The identified OSCC-related miRNAs and their potential target genes were analyzed with bioinformatic analyses, and the data were subjected to Ingenuity Pathway Analysis (IPA) to clarify functional networks and gene ontologies of the identified exosomal miRNAs secreted by OSCC cells. Results: Comparison with HNOKs detected 8 upregulated and 12 downregulated miRNAs in OSCC-secreted exosomes. The potential target mRNAs of these dysregulated miRNAs were suggested by IPA, and 6 significant genetic networks were indicated by genetic network analysis. Furthermore, 4 crucial upstream miRNAs—miR-125b-5p, miR-17-5p, miR-200b-3p, and miR-23a-3p—were identified. miR-125b-5p was a central node in the most significant network. Gene ontology analysis showed significant enrichment of genes with cancer-related functions, such as molecular mechanisms of cancer, cell cycle, and regulation of the epithelial-mesenchymal transition. Conclusion: These results provide a comprehensive view of the functions of dysregulated exosomal miRNAs in OSCC, thus illuminating OSCC tumorigenesis and development.
Tomoyuki Matsui, Suzuro Hitomi, Yoshinori Hayashi, Ikuko Shibuta, Jo Otsuji, Masatoshi Ando, Takanobu Inada, Kumi Soma, Koichi Iwata, Tetsuo Shirakawa, et al.
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0648

Abstract:
Purpose: Infantile tissue injury induces sensory deficits in adulthood. Infantile facial incision (IFI) was reported to cause an enhancement of incision-induced mechanical hypersensitivity in adulthood due to acceleration of the trigeminal ganglion neuronal excitability. However, the effects of IFI on activation of microglia in the spinal trigeminal nucleus and its involvement in facial pain sensitivity is not well known. Methods: A facial skin incision was made in the left whisker pad in infant (IFI) and/or adult rats (AFI). Mechanical head withdrawal threshold and microglial activation in the trigeminal spinal nucleus were analyzed. Results: Mechanical pain hypersensitivity induced by AFI was significantly exacerbated and prolonged by IFI. The number of Iba1-immunoreactive cells in the trigeminal spinal nucleus following AFI was increased by IFI, suggesting that IFI facilitates microglial hyperactivation following AFI. Intraperitoneal administration of minocycline, a microglial activation inhibitor, suppressed the facial incision-induced microglial hyperactivation in the trigeminal spinal nucleus and the exacerbation of the facial mechanical pain hypersensitivity induced by IFI. Conclusion: These results suggest that facial trauma in infants causes hyperactivation of microglia in the trigeminal spinal nucleus following AFI, leading to the prolongation of the facial mechanical pain hypersensitivity.
Philippe François, Anis Remadi, Stéphane Le Goff, Sarah Abdel-Gawad, Jean-Pierre Attal, Elisabeth Dursun
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0448

Abstract:
Purpose: This study investigated the flexural properties, shear bond strength (SBS) and interface to dentin of three recently developed self-adhesive bulk-fill materials. Methods: Bars of Surefil One (SO), Cention N (CN), Activa BioActive Restorative (AB) and EQUIA Forte HT Fil (EQUIA) were tested for flexural strength and flexural modulus in self-curing and light-curing modes. In addition, SBS to dentin was tested in specimens without pretreatment and after application of universal adhesive (Scotchbond Universal). EQUIA was used as the control material. Results: The flexural properties were significantly better in light-curing mode for all materials except CN. CN had the highest SBS values after universal adhesive application (33.8 MPa), and SO had the highest SBS without pretreatment (20.9 MPa). Conclusion: The mechanical and adhesive properties of these new materials varied widely.
Sarinya Yingcharoenthana, Ruchanee Ampornaramveth, Keskanya Subbalekha, Phonkit Sinpitaksakul, Paksinee Kamolratanakul
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0515

Abstract:
A split-mouth single-blind randomized-controlled clinical trial study was designed to investigate the effect of local and systemic vitamin C administration on extraction wound healing. Thirty patients who underwent bilateral premolar extraction were randomly divided into three group pairs; group 1: control and systemic administration (Con/CSA), group 2: control and a combination of local and systemic administration (Con/CLSA), and group 3: systemic and a combination of local and systemic administration (CSA/CLSA). The vitamin C (600 mg) was taken by swallowing (systemic administration) or slow oral dissolution (combined local and systemic administration). The socket size and radiographic density were evaluated immediately after extraction, and 7 days and 21 days later. The results demonstrated that the percentage radiographic density of new bone formation in the socket did not differ significantly within each group. However, in the CSA and CLSA group there was an improvement of soft tissue healing based in terms of socket depth reduction at 21 days after extraction compared with the control (P < 0.05).
Yoshiyuki Amari, Toshiki Takamizawa, Ryo Kawamoto, Yasuhiro Namura, Ryosuke Murayama, Munenori Yokoyama, Akimasa Tsujimoto, Masashi Miyazaki
Journal of Oral Science, Volume 63, pp 133-138; https://doi.org/10.2334/josnusd.20-0420

Abstract:
Purpose: This study investigated the influence of professional mechanical tooth cleaning (PMTC) pastes on the surface texture of different subject materials. Methods: Two one-step PMTC pastes, Clinpro Cleaning Paste for PMTC (CP) and PRG Pro-Care Gel (PG), and multiple-step PMTC pastes, Merssage Regular (MR), Merssagge Fine (MF), and Merssage Plus (MP), were used. For comparison, PMTC was performed using distilled water without paste (DW). The subjected materials used were bovine enamel (ENA) and dentin (DEN), a resin composite (FSU), and lithium disilicate (IEC). The prepared specimens were polished using a #2000-grit silicon carbide paper. PMTC was performed using a brush at 1,000 rpm for 15 s. Results: The surface roughness (Ra) values of the specimens before and after PMTC were measured by laser scanning microscopy. The Knoop hardness number (KHN) of the subjected material was obtained. The types of PMTC pastes and subject materials had a significant influence on the Ra values and KHN. For the majority of subject materials, the descending order of Ra values after PMTC was MR > MF > CP > PG > MP > DW. The descending order of KHN of the materials was IEC > ENA > FSU > DEN. Conclusion: Although one-step PMTC pastes appeared to be effective, it is important to consider the subject material during PMTC.
Taichi Ishikawa, Shiho Sugawara, Hidemichi Kihara, Tomohito Hanasaka, Wataru Hatakeyama, Minoru Sasaki, Hisatomo Kondo
Journal of Oral Science; https://doi.org/10.2334/josnusd.21-0130

Abstract:
Purpose: To determine the effects of titanium nanoparticles, that may have been scattered after dental implant placement, on gene and promoter expression, and gingival tissue. Methods: Ca9-22 cell lines were used as gingival epithelial cells to assess the effects of titanium dioxide nanomaterials as titanium nanoparticles. Cells were cocultured with or without titanium dioxide nanomaterials prior to gene and promoter expression analysis. Expression of interleukin-13α2 receptor was investigated using real-time quantitative reverse-transcription polymerase chain reaction and immunofluorescence staining. Additionally, the enhanced messenger ribonucleic acid (mRNA) expression of transforming growth factor β1 was analyzed using the same method. Results: Titanium dioxide nanomaterials affected gene and promoter expression in Ca9-22 cells: among the 160 upregulated genes, the upregulation of IL13RA2, which encodes interleukin-13α2 receptor, was the highest (8.625 log2 fold change). Immunofluorescence staining confirmed the increased expression of interleukin-13α2 receptor, which enhanced transforming growth factor β1 expression by stimulation with interleukin-13. Conclusion: Titanium dioxide nanomaterials applied on the gingival epithelium around the dental implant may increase interleukin-13α2 receptor expression. In turn, this can enhance the secretion of transforming growth factor β1, which is known to promote the differentiation of osteoclasts involved in bone resorption, and potentially affect gingival tissue.
Hin Nam Liu, Andy W. K. Yeung, W. Keung Leung
Journal of Oral Science, Volume 63, pp 201-208; https://doi.org/10.2334/josnusd.20-0565

Abstract:
This report identifies the top cited papers in the field of periodontal regeneration since inception of the concept. Using the H-classics approach, 132 papers published between 1970 and 2012 were identified, with 230.0 ± 175.6 (mean ± SD) citations and 10.4 ± 11.5 citations/year. There were 46 clinical reports, 28 animal studies, 23 in vitro studies, 30 reviews, 3 systematic reviews, and 2 combined animal and in vitro studies. Analysis of covariance showed that institution number (≥3, P = 0.011), journal impact factor at publication (>3.0, P = 0.001) and study type (in vitro/reviews vs. clinical trials/animal studies, P = 0.024) were significantly associated with citations/year. This study has characterized the most influential literature in the field of periodontal regeneration and serves as a quick reference resource.
Samuel Rodríguez-López, Matías Ferrán Escobedo Martínez, Jorge Pesquera Velasco, Luis Junquera, María García-Pola
Journal of Oral Science, Volume 63, pp 257-262; https://doi.org/10.2334/josnusd.21-0019

Abstract:
Purpose: The present study aimed to analyze in a Spanish population sample the compliance of the anterior maxillary teeth to the dental esthetic proportions described in the literature. Methods: Photographs of the smiles of 78 individuals were calibrated and digitally analyzed considering the following proportions: golden proportion (GP), recurring esthetic dental (RED), golden percentage (GPG), Preston’s proportion and Modified golden percentage (MGPG). For statistical analysis, the t-test of an independent sample was applied, and compliance percentages for each standard were recorded. Results: The existence of RED 70% or 80% has not been registered. The percentages of compliance with GP were within a range between 0% and 16%. The mean tooth width ratios were adjusted to the values described by Preston (P > 0.05), but the compliance percentages were low (3.33-25%). GPG only presented high percentages of compliance in the lateral incisors (53.33-62.5%). MGPG showed the highest percentages of compliance (50-68%). Conclusion: After analyzing a Spanish population sample using smile photographs for the first time, GP, RED, GPG and Preston’s proportion standards are not fulfilled and therefore, not suitable for treatments that seek a smile that reproduces natural principles. However, the values designated by MGPG with a deviation of ±1% are largely applicable for treatments that aim for a natural smile.
Tatsuro Kobayashi, Shigehiro Abe, Naoko Yokomizo, Hisataka Kitano, Takashi Ono, Toshiaki Takeda, Yutaka Kobayashi
Journal of Oral Science, Volume 63, pp 283-285; https://doi.org/10.2334/josnusd.20-0600

Abstract:
The condyle is the most common site of mandibular fracture. In the present study, an attempt was made to utilize three-dimensional computed tomography (3D-CT) images to evaluate mandibular condyle fractures and identify prognostic indicators of malocclusion after closed treatment. Accurate morphometric measurements were performed using 3D-CT images obtained before trauma, after trauma, and after healing. Morphometry revealed significant differences in loss of ramus height (LRH) and lateral movement length in patients with malocclusion, and significant LRH differences in patients with other maxillomandibular fractures after healing, or in those with dislocation-displacement. The present method of 3D-CT image analysis appears useful for evaluation of condylar fractures.
Shuichi Nishikubo, Shouhei Ogisawa, Junya Nakajima, Hiroaki Azaki, Keiji Shinozuka, Morio Tonogi
Journal of Oral Science, Volume 63, pp 298-300; https://doi.org/10.2334/josnusd.21-0151

Abstract:
Backsliding is a major problem when moving the maxilla significantly forward in orthognathic surgery. For example, in sleep surgery, maxillomandibular advancement is an application of orthognathic surgery, and it is well known that the anterior movement of the maxilla back and forth is an important factor that greatly widens the pharyngeal airway. However, postoperative backsliding is a major problem in this surgery. Therefore, a surgical method was devised to prevent the maxilla from retracting by adjusting the bone when moving the maxilla forward.
Seigo Ohba, Rena Shido, Izumi Asahina
Journal of Oral Science, Volume 63, pp 295-297; https://doi.org/10.2334/josnusd.21-0163

Abstract:
The aim of this study was to clarify whether hydroxyapatite/collagen composite material (HAp/Col) could be useful as a graft material for maxillary sinus floor augmentation (MSFA). MSFA and implant placement were performed simultaneously. When the lateral approach was employed, 3 out of 19 implants failed in 3 maxillary sinuses (success rate; 84.2%), and in these cases the alveolar bone heights, cortical bone thicknesses and values of the implant stability quotient were smaller. If alveolar the bone height, cortical bone thickness, and healing period are optimized, HAp/Col can be a useful graft material for MSFA.
Yasuki Uchida, Yasuhiro Namura, Mizuki Inaba, Ayaka Osada, Tasku Charleston-Coad, Yoshiki Nakamura, Mitsuru Motoyoshi
Journal of Oral Science, Volume 63, pp 270-274; https://doi.org/10.2334/josnusd.21-0012

Abstract:
Purpose: The aim of this study was to investigate the stability of orthodontic anchor screws (OASs) in the mid-palatal area according to pre-drilling diameter. Methods: The success rate of 161 OASs (83 patients, φ2.0 mm, 6.0 mm in length) placed in a corresponding area to the mesial and distal borders of the first molar (mesial zone and distal zone) was assessed according to placement location and pre-drilling diameter (1.2 and 1.5 mm). Placement torque values from 73 OASs with a pre-drilling diameter of 1.2 mm were compared between success and failure groups. Results: The success rates of OASs pre-drilled with φ1.2 and 1.5 mm were 94.5% and 83.0%, respectively (P < 0.05); corresponding rates in the mesial zone were 100.0% and 77.3% (P < 0.005), and those in the distal zone were 89.2% and 88.6%, respectively. Placement torques of OASs predrilled with φ1.2 mm in the success and failure groups were 25.9 and 19.2 N·cm, respectively (P < 0.05). Conclusion: A smaller pre-drilling diameter was associated with a higher success rate of OASs in the mid-palatal area, especially in the mesial zone. When pre-drilling diameter of 1.2 mm was used for φ2.0 mm OAS, greater placement torque was indicative of greater OAS stability.
Marco Cabras, Alessio Gambino, Roberto Broccoletti, Savino Sciascia, Paolo G. Arduino
Journal of Oral Science, Volume 63, pp 217-226; https://doi.org/10.2334/josnusd.21-0016

Abstract:
A systematic review was carried out to identify if periprocedural administration of systemic antibiotics could decrease risk of medication-related osteonecrosis of the jaws (MRONJ) in patients under antiresorptive and/or biologic agents for teeth extraction. PubMed/MEDLINE and Scopus were systematically searched for case-series with more than 10 patients, retrospective/prospective studies, and trials concerning this issue. Manual searching of references from previous reviews was also carried out. Of 1,512 results, 17 studies were included, focusing on antibiotics for extraction in patients under intravenous bisphosphonates (8 studies), oral bisphosphonates (2 studies), oral and intravenous bisphosphonates (6 studies), and denosumab (1 study), of which 12 performed dental extraction with surgical flap. With no trials found, “quality in prognosis studies” (QUIPS) tool was used to evaluate risk of bias. First-line treatment was 2-3 grams of oral amoxicillin in 76.4% of studies; 300-600 mg of clindamycin was the alternative treatment in 23.5% of studies. Treatment ranged from 3 to 20 days, consisting of 6-7 days in 47% of studies. No microbiologic insight was provided. A significantly higher risk of MRONJ for patients unexposed to antibiotics was provided in one retrospective study. QUIPS tool revealed moderate-high risk of bias. With empirical data from bias-carrying, heterogeneous observational studies, the validity of antibiotics is yet to be established.
Hiroyuki Hato, Ken-Ichiro Sakata, Jun Sato, Akira Satoh, Toshihiko Hayashi, Yoshimasa Kitagawa
Journal of Oral Science, Volume 63, pp 289-291; https://doi.org/10.2334/josnusd.21-0154

Abstract:
This study aimed to determine the appropriate treatment methods and evaluate associated factors by comparing nonoperative treatment alone with a combination of both nonoperative and surgical treatment in 34 patients with mandibular osteoradionecrosis (mORN). The associated cure factors were analyzed by Cox regression. Propensity scores were calculated from factors that were not significant in the univariate analysis and used as covariates in the multivariate analysis. The cure rate among patients who received nonoperative and surgical treatment was higher than that observed with nonoperative treatment alone. Only the treatment method was associated with cure in both univariate and multivariate analyses.
Yuwa Takahashi, Norihisa Watanabe, Noriaki Kamio, Ryutaro Kobayashi, Toshimitsu Iinuma, Kenichi Imai
Journal of Oral Science, Volume 63, pp 1-3; https://doi.org/10.2334/josnusd.20-0388

Abstract:
Coronavirus infectious disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was declared a pandemic in March 2020 by the World Health Organization. Periodontitis, one of the most prevalent diseases worldwide, leads to alveolar bone destruction and subsequent tooth loss, and develops due to pro-inflammatory cytokine production induced by periodontopathic bacteria. Periodontopathic bacteria are involved in respiratory diseases, including aspiration pneumonia and chronic obstructive pulmonary disease (COPD), and other systemic diseases, such as diabetes and cardiovascular disease. Patients with these diseases have an increased COVID-19 aggravation rate and mortality. Because aspiration of periodontopathic bacteria induces the expression of angiotensin-converting enzyme 2, a receptor for SARS-CoV-2, and production of inflammatory cytokines in the lower respiratory tract, poor oral hygiene can lead to COVID-19 aggravation. Conversely, oral care, including periodontal treatment, prevents the onset of pneumonia and influenza and the exacerbation of COPD. The reduced chance of receiving professional oral care owing to long-term hospitalization of patients with COVID-19 may increase the aggravation risk of infection in the lower respiratory tract. It can be hypothesized that periodontopathic bacteria are involved in the COVID-19 aggravation and therefore, the management of good oral hygiene potentially contributes to its prevention.
Yohei Okazaki, Yasuhiko Abe, Kana Dainobu, Shogo Iwaguro, Ryoji Kato, Kazuhiro Tsuga
Journal of Oral Science, Volume 63, pp 98-100; https://doi.org/10.2334/josnusd.20-0158

Abstract:
The purpose of this study was to clarify the usage and understanding of denture adhesives among 1,825 denture wearers, aged 40 years and older in Japan, using a web-based survey. The NTTCom Online survey (a closed investigation) was conducted over a period of 4 days using a 13-item questionnaire about denture adhesives. Results showed that 67.1% of the respondents were satisfied with their dentures; 81.5% of respondents knew about denture adhesive, but only 347 (19.0%) had used the product. Products used by the 347 denture wearers included cream type (79.7%), cushion type (16.2%), and powder type (3.2%). The most common reason for the selection of a particular type was “Saw the product” (59.9%), followed by “Saw an advertisement” (19.3%), and “Explanation at a dental clinic” (8.4%). The response of “Ill-fitting denture” significantly affected the response of “Use of denture adhesives” (chi-square test; P < 0.001). Moreover, the sensitivity (0.56) was lower than the specificity (0.75). These findings show that denture adhesives were not always necessary for those with ill-fitting dentures.
Masahiro Kondo, Hirofumi Aboshi, Masaaki Yoshikawa, Ayano Ogata, Ryosuke Murayama, Masami Takei, Shin Aizawa
Journal of Oral Science, Volume 63, pp 54-58; https://doi.org/10.2334/josnusd.20-0138

Abstract:
Age estimation of unidentified bodies is important in forensic medicine and crime scenes. There is accumulating evidence that DNA methylation in the human genome isolated from body fluids changes with age. Most of the data have been obtained by pyrosequencing. In the forensic field, a simple, quick, and economical method is required to evaluate the age of various types of samples. In this study, an age estimation method based on methylation levels of DNA extracted from teeth using real-time methylation-specific PCR (MSP) was developed. The CpG island in the upstream region of ELOVL2, which is known as a validated biomarker in blood samples, was selected as a target site. The CpG methylation levels highly correlated with age (r = 0.843, n = 29). Age-related increase in DNA methylation levels was not affected by sex differences. In addition, the simple regression model based on methylation status of the CpG island exhibited moderate accuracy with a mean absolute deviation between chronological age and predicted age of 8.94 years. The results imply that real-time MSP can be a new tool to perform age prediction of unidentified bodies in forensic scenes.
Valentina Spicciarelli, Crystal Marruganti, Carla Di Matteo, Marco Martignoni, Hani Ounsi, Tiziana Doldo, Marco Ferrari, Simone Grandini
Journal of Oral Science, Volume 63, pp 70-74; https://doi.org/10.2334/josnusd.20-0338

Abstract:
Purpose: The aim of this study was to compare the influence of the number of coronal walls and post-endodontic restorations on the mechanical strength of 165 recently extracted endodontically treated maxillary premolars. Methods: The teeth were divided into 3 control (no post) and 3 test groups according to the number of residual walls. Each test group was divided into subgroups according to the type of post-endodontic restoration (single, oval, and multi-post techniques). Samples were prepared conforming to the assigned subgroup. A universal loading machine applied a load parallel to the longitudinal axis of the teeth, thus simulating physiological occlusion. ANOVA and the Kruskal Wallis test were used for comparisons (P ≤ 0.05), and Tukey’s test for multiple comparisons. Results: For intact teeth, significant differences were found among all 3 subgroups, with single post showing the highest values. For 3 residual walls, oval post resulted in significantly lower values than single and multi-post systems. For 2 residual walls, the multi-post technique showed almost twice the resistance of oval post restorations. Conclusion: In oval canals the use of a single or multi-post technique increased post-and-core resistance even in intact teeth, whereas oval fiber posts showed no improvements. Multi-post design improved fracture resistance mostly in maxillary premolars lacking both marginal ridges.
Yuto Tanaka, Toru Yoshida, Yoshiaki Ono, Yoshinobu Maeda
Journal of Oral Science, Volume 63, pp 41-45; https://doi.org/10.2334/josnusd.20-0030

Abstract:
Purpose: Whether it is possible to prevent mechanical stress on teeth via an occlusal splint remains to be clarified. This study aimed to assess the same by simultaneously recording the occlusal pressure and strain on the teeth in humans. Methods: Eleven participants (five women and six men; mean age 25.7 years) were enrolled in this study. Hard and soft oral appliances were fabricated for the maxillary arch of each participant. The strain on the four target teeth (right maxillary and mandibular first premolars, and first molars) and occlusal pressure were concurrently measured, while the participants performed maximum voluntary teeth clenching under each condition (hard, soft, or no occlusal splint). Results: Compared to the absence of an occlusal splint, hard occlusal splints generated less strain on molar teeth but more strain on premolar teeth, while soft occlusal splints did not lower the strain on all target teeth significantly. Conclusion: Considering the limitations of this study, hard occlusal splints should be used for the protection of molar teeth but for premolar teeth caution is required and depends on the case. On the other hand, soft occlusal splints may not have any benefit for the protection of either type of teeth for patients exhibiting excessive occlusal pressure.
Mika Furuchi, Yoshimasa Takeuchi, Atsushi Kamimoto, Hideo Matsumura, Hideyuki Imai, Hiroyasu Koizumi
Journal of Oral Science, Volume 63, pp 119-120; https://doi.org/10.2334/josnusd.20-0558

Abstract:
Cast titanium restoration for molars has high biocompatibility and is covered by the Japanese national health insurance. Titanium casting requires specific investment material and casting apparatus. A cast restoration for the mandibular left second molar was fabricated using titanium in this study. A wax pattern fabricated on a definitive cast was invested in calcium aluminate-bonded magnesia investment material. Titanium was cast using an argon gas pressure one-chamber casting apparatus. No defects were observed on the surface and the hole was clearly reproduced. A smooth surface on the restoration was obtained by polishing at low speed. Reproductivity and polishing properties of the titanium restoration fabricated in this study were comparable to those of conventional dental metal restorations.
Enri Nakayama, Haruka Tohara, Mitsuyasu Sato, Kimiko Abe, Masanori Kimura, Mao Watanabe, Masato Iida, Koichiro Ueda
Journal of Oral Science, Volume 63, pp 79-82; https://doi.org/10.2334/josnusd.20-0414

Abstract:
Purpose: To examine the relationship between oral intake function and oral health status in convalescent inpatients. Methods: Subjects were 222 patients admitted to a convalescent hospital between 1 January and 30 June 2018. Investigation items were age, sex, causative disease, body mass index, functional oral intake scale (FOIS), functional independence measure, occlusal contact, assistance with oral cleaning, and oral health assessment tool (OHAT) scores. Multiple regression analysis was performed with FOIS as the dependent variable, and investigation items were related to FOIS as independent variables. Results: Results of multiple regression analysis for all patients suggested that saliva and denture scores were significantly associated with FOIS. However, analysis excluding non-oral feeding patients did not show a significant association between FOIS and OHAT scores. Conclusion: The results of this study suggest that oral health status is associated with oral intake function. In addition, the oral health status of inpatients may be strongly related to whether or not they are eating orally. Therefore, it is necessary to take good care of oral health in non-oral feeding patients in the convalescent ward.
Maria Herrala, Jopi J. W. Mikkonen, Paula Pesonen, Reijo Lappalainen, Leo Tjäderhane, Raija K. Niemelä, Hubertus Seitsalo, Tuula Salo, Sami Myllymaa, Arja M. Kullaa
Journal of Oral Science, Volume 63, pp 22-26; https://doi.org/10.2334/josnusd.19-0504

Abstract:
Purpose: To investigate inter- and intra-individual variation in the levels and outputs (concentration multiplied by salivary flow rate) of salivary metabolites in patients with primary Sjögren’s syndrome (pSS). Methods: A total of 56 samples of stimulated saliva were collected from 14 female pSS patients during four laboratory visits within 20 weeks and analyzed using proton nuclear magnetic resonance spectroscopy. Single saliva samples from each of 15 controls were also analyzed. Results: Among 21 quantified metabolites, choline was significantly elevated in the pSS patients at each time point (P ≤ 0.015), taurine at the last three time points (P ≤ 0.013), alanine at the last two time points (P ≤ 0.007) and glycine at the last time point (P = 0.005). Inter-individual variation in metabolite concentrations was generally larger among the patients than among the controls, and significantly large variations were observed for glycine (P ≤ 0.007, all time points), choline (P ≤ 0.033, three last time points) and alanine (P = 0.028, baseline). Metabolite output analysis showed that choline had the lowest intra-patient variation. Conclusion: In spite of considerable intra- and inter-individual variation, levels and outputs of specific metabolites in patients with pSS differ from those in controls, and may be potentially applicable as new biological markers for monitoring of the response to treatment.
Takayuki Yoneyama, Takao Hanawa
Journal of Oral Science, Volume 63, pp 50-53; https://doi.org/10.2334/josnusd.20-0239

Abstract:
Purpose: Ni-Ti alloy has been increasingly applied to dental and medical devices, however, it contains nickel, which is known to have adverse effects on the human body. The purpose of this study was to form a nickel-free surface oxide layer on Ni-Ti alloy by electrolytic treatment for better biocompatibility. Methods: Ni-49.15Ti (mol%) alloy was used, and the electrolytic treatment was performed in the electrolytes under 50 V for 30 minutes. The electrolytes were composed of lactic acid, water, and glycerol with different compositions. Surface analysis and characterization of Ni-Ti alloy were carried out by means of X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Results: Results indicated that the outmost surface oxide layer was nickel-free when using an electrolyte comprising 7.1% lactic acid, 57.2% water, and 35.7% glycerol by volume. The composition of this nickel-free surface oxide layer was determined as TiO1.92(OH)1.35 ∙ 0.43H2O by XPS, similar to that of unalloyed titanium. The thickness of this nickel-free layer was estimated at 6.4 nm by AES. Conclusion: The nickel-free surface oxide layer produced on Ni-Ti alloy is considered to improve the biocompatibility of medical and dental devices having shape memory effect and/or super-elasticity.
Takaaki Sato, Yusuke Matsuyama, Takeo Fujiwara, Junji Tagami
Journal of Oral Science, Volume 63, pp 27-30; https://doi.org/10.2334/josnusd.19-0534

Abstract:
Minimal intervention is generally achieved by using direct composite resin (CR) restorations. However, deep caries lesions may lead to pulpal complications. This study evaluated the risk of endodontic complications after CR restoration in relation to depth of caries lesions. Data on 507 teeth from 316 adults treated with CR were analyzed. Caries depth was expressed as a percentage of the distance between the outer edge of the dental enamel and the pulp base on preoperative radiographs. The interval between CR restoration and follow-up root canal treatment was obtained from electronic treatment records for a period of 24 months. A Cox proportional hazards model was used to investigate the association between risk of endodontic complications and caries depth. Sixteen teeth (3.2%) required root canal treatment within 24 months. No root canal treatment was required after CR treatment for caries affecting <50% of the outer edge of enamel and pulp. As compared with CR treatment of caries lesions with a size of <80%, there was a significantly higher risk of root canal treatment for caries lesions with a size of 80% to 89% (hazard ratio, [95% CI]: 34.68 [4.23-284.11]) and ≥90% (92.01 [10.36-817.41], respectively).
Jingran Zhang, Zhen Huang, Yu Cai, Qingxian Luan
Journal of Oral Science, Volume 63, pp 59-64; https://doi.org/10.2334/josnusd.20-0157

Abstract:
Purpose: To establish a digital assessment method for changes in gingiva morphology following initial periodontal therapy. Methods: Ten periodontal-healthy participants were selected, and digital models obtained by intraoral scanning and digitizing conventional impressions. Using dentition as a reference, best fit alignment between digital models was carried out. Root mean square (RMS) was calculated to evaluate differences in models, and gingival volume discrepancy (GVD) was calculated after combining separated models. Trueness of intraoral scanning used on the gingiva was evaluated using RMS and GVD between intraoral and conventional models with conventional models as references; precision was evaluated among different intraoral models of one participant. Twenty-three periodontitis-affected participants underwent intraoral scanning immediately after supragingival scaling and two weeks after initial periodontal therapy. The GVD of gingiva between two digital models was calculated to assess gingival changes and related factors after therapy. Results: Trueness of intraoral scanning used on the entire gingiva was 83.65 ± 14.43 μm; precision was 70.71 ± 25.58 μm; GVD error measured by digital models was 15.28 ± 10.00 mm³. Gingival volume in periodontitis-affected participants decreased 104.04-1155.09 mm³ after therapy. Probing depth, bleeding index, and keratinized gingival width positively correlated with changes in gingival volume. Conclusion: Intraoral scanning can be recommended as a method of evaluating morphological changes in gingiva.
Ajay Ranganathan, Suma Karthigeyan, Rahila Chellapillai, Venkateshwaran Rajendran, Tamizhesai Balavadivel, Anand Velayudhan
Journal of Oral Science, Volume 63, pp 14-17; https://doi.org/10.2334/josnusd.19-0493

Abstract:
This study aims to evaluate the impact of adding a novel tricyclodecane dimethanol diacrylate comonomer on the flexural strength (FS) and impact strength (IS) of heat-cure denture base resin at 10% and 20% (v/v) concentrations. To test the FS and IS, a sum total of 150 bar-shaped specimens were prepared according to standard specifications. For the FS, the specimens were subjected to the three-point bend test with a span length of 50 mm. For the IS, Charpy’s test was executed with a span length of 60 mm. The FS was measured in MPa, and the IS was measured in kJ/m2. There was a statistically significant difference (P < 0.001) between the control and experimental groups in that both the FS and IS were increased in the experimental groups relative to the control group.
Motohiro Ito, Yusuke Hayashi, Kunihito Matsumoto, Yoshinori Arai, Kazuya Honda
Journal of Oral Science, Volume 63, pp 87-91; https://doi.org/10.2334/josnusd.20-0479

Abstract:
Purpose: The spatial resolution of cone-beam computed tomography (CBCT) in small fields of view (FOVs) is important for clinical applications. However, it is difficult to measure spatial resolution reliably due to error factors such as noise. The aim of this study was to obtain a modulation transfer function (MTF) more accurately. Methods: A CBCT apparatus was used with small FOV. An aluminum pipe slightly tilted at an inclination ratio of 77/3 (25.7) was used as the measurement phantom. The MTF was calculated from the edge image of the phantom. The actual oversampling ratio was determined by regression analysis. The experiment was repeated 16 times and the edge-spread function (ESF) was approximated by the least-square method. Furthermore, a low-pass filter (LPF) was applied to eliminate the component at frequencies above the Nyquist frequency. Finally, the MTF was calculated from the pre-processed ESF. Results: Results showed that pre-processing reduced the noise of the ESF. The MTFs at frequencies of 1.0 and 2.0 LP/mm were 0.59 and 0.18, respectively, in air and 0.52 and 0.16, respectively, in water. Conclusion: The repeating-edge oversampling method combined with ESF pre-processing improved the accuracy of the MTF under clinically relevant conditions with a phantom.
Lamia S. Mokeem, Lisa H. Willis, L. Jack Windsor, N. Blaine Cook, George Eckert, Richard L. Gregory
Journal of Oral Science, Volume 63, pp 75-78; https://doi.org/10.2334/josnusd.20-0073

Abstract:
The purpose of this study was to explore the effects of nicotine on the activity of Streptococcus mutans (S. mutans) in soft drinks. Regular soft drinks contain large proportions of high-fructose corn syrup (HFCS), which increases the activity of S. mutans resulting in high-caries risk compared with sugar-free soft drinks. Nicotine use exhibits a strong correlation with increased S. mutans biofilm formation. The soft drinks chosen were (Coca-Cola Classic, Diet Coke, Coca-Cola Zero Sugar, Caffeine-Free Coca-Cola, Caffeine-Free Diet Coke, Caffeine-Free Coca-Cola Zero Sugar). S. mutans was grown overnight in tryptic soy broth; nicotine was diluted in tryptic soy broth supplemented with 1.0% sucrose followed by soft drinks in dilution of 1:3. Total growth absorbance and biofilm growth were determined by spectrophotometry, absorbance measured to determine biofilm formation, and metabolic activity quantified. One-way ANOVA showed a considerable effect for HFCS and caffeine in the presence of nicotine and their interaction in all measures. Results showed sugar-free caffeinated colas demonstrated significant effect in inhibiting S. mutans biofilm formation and metabolic activity with nicotine. Nicotine-induced S. mutans increased biofilm formation and metabolic activity in the presence of HFCS and caffeine in soft drinks. In conclusion, smokers should consider sugar-free caffeinated versions to minimize the chance of developing dental caries dut to the reduction of biofilm formation.
Yohei Nakayama, Koji Mizutani, Yuka Tsumanuma, Hiroyuki Yoshino, Norio Aoyama, Koji Inagaki, Manabu Morita, Yuichi Izumi, Shinya Murakami, Hidenori Yoshimura, et al.
Journal of Oral Science, Volume 63, pp 114-118; https://doi.org/10.2334/josnusd.20-0288

Abstract:
Few prospective studies have reported the effects of periodontal therapy on patients who attempted to quit smoking. This study aimed to assess how smoking cessation affects periodontal therapy. Twenty-five smokers with periodontitis were investigated by dividing them into two groups, a smoking cessation support group and a continued smoking group. Those in the support group received counseling and nicotine replacement therapy, followed by periodontal treatment conducted by dentists who had completed an e-learning course on smoking cessation. Clinical parameters were measured at baseline, 3, and 6 months. Most clinical parameters improved for those in the smoking cessation support group. There were no significant improvements in bleeding on probing (BOP) or the number of severe periodontal disease sites in the continued smoking group. Probing pocket depth (PPD) and clinical attachment levels (CAL) at sites that received scaling and root planing (SRP) significantly improved in all subjects. BOP did not improve at reevaluation in the smoking relapse subgroup. Patients in the smoking cessation support program led by dental professionals showed more improvement in BOP than those in the continued smoking group.
Yukiko Yamazaki, Takao Ito, Toru Ogawa, , Yukie Yamada, Taizo Hamada, Keiichi Sasaki
Journal of Oral Science, Volume 63, pp 111-113; https://doi.org/10.2334/josnusd.20-0245

Abstract:
A study was conducted to evaluate the basic mechanical properties of a pure cellulose nanofiber (CNF) material in comparison with a commercial denture base material (polymethylmethacrylate [PMMA] acrylic resin). The working hypothesis was that CNFs have potential for use as denture base materials. Pure CNF specimens fabricated under various conditions were examined. The flexural strength (FS) and flexural modulus (FM) of the specimens were measured using the three-point bending test, and the morphologies of the fractured surfaces were examined using scanning electron microscopy. Addition of tricalcium phosphate to dehydrate the CNFs did not improve their FS or FM. Conversely, substitution with methanol effectively improved the dehydration process and significantly affected the mechanical properties of the CNFs. As the degree of CNF defibration increased, the physical properties of the specimens improved significantly. However, addition of CNFs to PMMA liquid to create CNF-reinforced PMMA did not improve the mechanical properties. Pure CNF specimens fabricated under particular conditions had higher FS and FM values than the control, suggesting that CNFs have potential as a “petroleum-free” alternative to acrylic resin denture base materials. Pure CNF would be potentially useful as a denture base material, and presumably applicable to computer-aided design/manufacture (CAD/CAM).
Alex Solderer, , Yann Gager, Kai Fischer, Patrick R. Schmidlin
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0444

Abstract:
Purpose: To determine the impact of experimentally preformed peri-implant crater-shaped bone defects on the evolution of in situ microbiota and development of bone defects compared to those induced over time by ligature placement only. Methods: Implants were installed in the mandibles of eight dogs. Standardized bone defects were preformed in four test animals but not in the other four control animals, prior to implant (3.3 mm × 8 mm) installation. After 2 months of healing, peri-implantitis was induced with silk ligatures in both groups for 2 months. Microbial samples were obtained from implants and teeth for analysis at three time points (qPCR), and the average depths of the bone defects were measured. Results: At the baseline, the total marker load of periodontal-pathogenic bacteria (TML) for teeth accounted for 5.2% (0-17.4%). After implant healing, TMLs for implants and teeth were comparable (7.1% [0.3-17.4%]). The TML of both groups was 3.5%, 2 months after ligature placement. Bone defects had a mean depth of 1.84 mm at preformed defects and 1.64 mm at control sites (P > 0.05). Conclusion: Preformed defects in the test group showed comparable results to the control group in terms of TML, the incidence of periodontal-pathogenic bacteria, and bone defect depth.
Mako Sano, Hiroshi Shiga
Journal of Oral Science, Volume 63, pp 145-147; https://doi.org/10.2334/josnusd.20-0549

Abstract:
Purpose: This study aimed to clarify whether occlusal force and masticatory performance reduced in elderly adults and whether these parameters were affected by age. Methods: Seventy-eight elderly adults (elderly group) and 76 young adults (control group) with natural dentition were asked to maximally clench for 3 s, and occlusal force was calculated. The amount of glucose extraction after chewing a gummy jelly was measured as the parameter for masticatory performance. Occlusal force and masticatory performance were compared between the elderly and control groups. The correlation between age and occlusal force and between age and masticatory performance was also investigated. Results: Occlusal force was significantly smaller in the elderly group (P < 0.05). Masticatory performance was lower in the elderly group, but this difference was not statistically significant. No significant correlation was observed between age and occlusal force in the control group, but a negative correlation was found in the elderly group (P < 0.05). No significant correlation was found between age and masticatory performance in either group. Conclusion: Occlusal force was affected by age and reduced significantly, whereas masticatory performance was not affected by age and was maintained in elderly adults.
Hisashi Suguro, Anna Nishihara, Takahito Tamura, Takeshi Nakamura, Yurika Toyama, Osamu Takeichi
Journal of Oral Science; https://doi.org/10.2334/josnusd.20-0466

Abstract:
Purpose: This study evaluated the precision of electronic working length by microcomputed tomography using two electronic apex locators (EALs). Methods: Twenty single-rooted permanent teeth without caries or restorations were selected as the subject teeth. The positions of the minor apical constriction (AC) and major apical foramen (AF) were measured by electronic root canal length, and microcomputed tomography was performed with the file inserted and fixed in the root canal. All teeth were measured individually and independently by two operators. The Mann-Whitney U-test was used to statistically test the AC and AF values using two EALs; P < 0.05 was defined as statistically significant. Results: This was 65.0% within 1.5 mm in the case of two EALs on AC. This was more than 90.0% within 1.0 mm in the case of two EALs on AF. Comparison of the differences between the respective AC and AF of the measurements obtained using the two EALs revealed no significant difference. Conclusion: The two EALs are devices that can greatly improve the accuracy of WL control.
Gaspare Palaia, Leonardo D’Alessandro, Daniele Pergolini, Raffaella Carletti, Cira R. T. Di Gioia, Umberto Romeo
Journal of Oral Science, Volume 63, pp 280-282; https://doi.org/10.2334/josnusd.20-0665

Abstract:
Blue diode laser emits a 445 nm wavelength light, which is extremely effective with hemoglobin, and has an optimal hemostatic effect. This work analyzes its thermal effects and clinical efficacy, when used to perform excisional biopsies. Forty-two excisional biopsies were performed with the laser; then, the extent of perincisional thermal effects was evaluated and patients were followed up. Average alteration on epithelial tissue was 507.07 µm, and on connective tissue was 320.39 µm. In all the cases, it was possible to obtain a histological diagnosis. Diode lasers can be safely used to perform biopsies; various intra- and postoperative advantages were confirmed.
Saori Yamada, Susumu Tanaka, Soju Seki, Mikihiko Kogo
Journal of Oral Science, Volume 63, pp 242-246; https://doi.org/10.2334/josnusd.20-0566

Abstract:
Purpose: The present study aimed to evaluate the effects of zinc deprivation on the properties of membrane and spike-discharge features of mesencephalic trigeminal neurons (MTNs), which are important sensory neurons for oral-motor reflexes and rhythmical jaw movements. Methods: Neonatal Sprague Dawley rats (P10-12) were distributed equally into a normal diet group and a zinc-deficient diet (ZD) group. Whole cell patch-clamp recordings were obtained from MTNs from coronal brain slices. Results: Passive membrane properties showed a modest depolarized membrane potential and decreased cell capacitance in the ZD group. Zinc deprivation decreased the minimal current amplitude, which induced an action potential and increased the amplitude of afterhyperpolarization following the action potential. Negligible changes were observed for other action potential properties. A decreased burst duration was observed, accompanied by hastened spike frequency adaptation in the burst discharge. There was no difference in the resonant properties at both the subthreshold depolarized potential and hyperpolarized membrane potential between the control and ZD groups. Conclusion: These results suggests that neither the persistent sodium conductance nor slow inwardly rectifying conductance were altered; however, there appeared to be an increase in Ca2+-dependent K+ conductance in zincdeficient MTNs.
Yuka Abe, Takashi Matsumoto, Hiroyuki Watanabe, Deepesh K. Gupta, Kazuyoshi Baba
Journal of Oral Science, Volume 63, pp 231-235; https://doi.org/10.2334/josnusd.20-0635

Abstract:
Purpose: To investigate the factors influencing patients’ willingness to replace removable dentures using structural equation modeling (SEM). Methods: A total of 153 patients who sought consultations for removable dentures self-evaluated denture quality using a visual analog scale (VAS); health-related quality of life using the 36-item Short-Form Health Survey; and oral health-related quality of life using the Oral Health Impact Profile. Dental clinicians evaluated denture quality using a VAS and by assessing the presence of defects. After being informed of various treatments, patients were asked whether they would prefer denture replacement. SEM was applied to analyze the relationships and interactive effects among the variables. Results: The final model showed high goodness-of-fit indices (chi-square/degree of freedom = 1.009, comparative fit index = 1.000, Tucker-Lewis index = 0.999, standardized root mean square residual = 0.421, and root mean square error of approximation = 0.008). SEM demonstrated that two latent constructs indirectly predicted patients’ willingness to replace dentures; the standardized total effects of good oral health and poor denture quality were −0.154 and 0.503, respectively. Conclusion: These findings provide a unified understanding of the shared decision-making process for denture replacement and highlight the pretreatment assessments that play a relevant role in patient treatment preferences.
Sheree Tredoux, Nichola Warren, Glynn D. Buchanan
Journal of Oral Science, Volume 63, pp 252-256; https://doi.org/10.2334/josnusd.20-0651

Abstract:
Purpose: This study investigated root number and canal configurations, including morphological variations, of mandibular first molars in a subpopulation of South Africans. Methods: Two calibrated examiners retrospectively evaluated 371 mandibular first molars by using high-resolution cone-beam CT images and the Vertucci classification system with the additions of Sert and Bayirli. Internal and external configurations were recorded, and correlations of sex and age with root number and canal configuration were determined with the chi-square and Fisher exact tests (P < 0.05). Results: Among mandibular first molars, 0.3% were single-rooted, 98.7% were two-rooted, and 1% were three-rooted. The most frequent configuration was Vertucci Type IV in mesial roots and Vertucci Type I in distal roots. Middle mesial canals were found in 20% and middle-distal canals in 7% of samples. The prevalence of third canals increased in mesial and distal roots as age increased (P > 0.05). Canal configuration and sex were not correlated (P > 0.05). Conclusion: Mandibular first molars exhibited diverse anatomic characteristics in this subpopulation. Clinicians should be aware of the possibility of additional canals in mandibular first molars, as treatment outcomes may be worse if canals are left untreated.
Sidra Abaid, Sobia Zafar, Estie Kruger, Marc Tennant
Journal of Oral Science, Volume 63, pp 247-251; https://doi.org/10.2334/josnusd.20-0596

Abstract:
Purpose: Many studies of tooth dimensions have reported both diversity among populations and sexual dimorphism. This study aimed to collect data on mesiodistal dimensions and sexual dimorphism of permanent teeth of contemporary Western Australian adolescents. Methods: The mesiodistal dimensions of teeth from 500 adolescents (177 males, 323 females; age, 13-18 years) were obtained from pre-orthodontic treatment digital dental records of examinations using Invisalign technology. Differences between contralateral teeth and sexual dimorphism were analyzed by using SPSS. Results: Mesiodistal dimensions significantly differed between right and left teeth in both sexes. Males had larger teeth than females, and the difference was significant for most teeth. Reverse dimorphism (females had slightly larger teeth than males) was observed for the maxillary second premolar. Mandibular canines exhibited the greatest dimorphism. In addition, secular trends—specifically, a reduction in the degree of dimorphism—were observed in mesiodistal dimensions. Conclusion: Mesiodistal dimensions significantly differed between teeth in contralateral quadrants, in both arches. Most teeth exhibited sexual dimorphism, which was the greatest for permanent mandibular canines. Dimorphism was less obvious in this population than in other populations.
Hidemichi Kihara, Shiho Sugawara, Jun Yokota, Kyoko Takafuji, Shota Fukazawa, Ayaka Tamada, Wataru Hatakeyama, Hisatomo Kondo
Journal of Oral Science, Volume 63, pp 212-216; https://doi.org/10.2334/josnusd.21-0072

Abstract:
This narrative review aims to provide an overview of recent studies and case reports on three-dimensional (3D) printing, and to verify the applicability of 3D printers in the field of dental prostheses. This review was performed by conducting a search of PubMed. The clinical application of fabricating a prosthesis made with cobalt-chromium is considered possible depending on the material and hardware of the 3D printer. However, it is currently difficult to assess the clinical use of 3D-printed zirconia crowns. Further research is required, such as verification of materials used, margin morphology, and hardware. Clinically acceptable results have been reported for patterns using 3D printers. Interim restorations made using a 3D printer have been reported with good results that are considered clinically usable. Dentures made with 3D printers need further verification in terms of strength and deformation. Custom trays made with 3D printers are clinically useful, however, issues remain with design time and effort. Although several studies have reported the usefulness of 3D printers, further verification is required since 3D printers are still considered new technology.
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