Multistability and hysteresis in states of oral microbiota: Is it impacting the dental clinical cohort studies?

INTRODUCTION: Microbiome from a "healthy cohort" is used as a reference for comparison to cases and intervention. However, the studies with cohort-based clinical research have not sufficiently accounted for the multistability in oral microbial community. The screening is limited to phenotypic features with marked variations in microbial genomic markers. Herein, we aimed to assess the stability of the oral microbiome across time from an intervention-free "healthy" cohort. METHODS: We obtained 33 supragingival samples of 11 healthy participants from the biobank. For each participant, we processed one sample as baseline (T0) and two samples spaced at 1-month (T1) and 3-month (T2) intervals for 16S ribosomal RNA gene sequencing analysis. RESULTS: We observed that taxonomic profiling had a similar pattern of dominant genera, namely, Rothia, Prevotella, and Hemophilus, at all time points. Shannon diversity revealed a significant increase from T0 (p < .05). Bray Curtis dissimilarity was significant (R = -.02, p < .01) within the cohort at each time point. Community stability had negative correlation to synchrony (r = -.739; p = .009) and variance (r = -.605; p = .048) of the species. Clustering revealed marked differences in the grouping patterns between the three time points. For all time points, the clusters presented a substantially dissimilar set of differentially abundant taxonomic and functional biomarkers. CONCLUSION: Our observations indicate towards the presence of multistable states within the oral microbiome in an intervention-free healthy cohort. For a conclusive and meaningful long-term reference, dental clinical research should account for multistability in the personalized therapy approach to improve the identification and classification of reliable markers.

Oral Porphyromonas gingivalis infection affects intestinal microbiota and promotes atherosclerosis.

AIM: The link between periodontitis and intestinal dysbiosis, two factors that contribute to atherosclerosis, has not been clearly defined. We investigated the integrative effects of oral infection with Porphyromonas gingivalis (PG), the major pathogen for periodontitis, on intestinal microbiota and atherosclerosis. MATERIALS AND METHODS: ApoE-/- mice were fed a normal chow diet (NC), a Western diet (WD) or a WD with oral PG infection (PG). The PG infection was investigated by placing a total of 109 CFUs of live PG into the oral cavity of each mouse using a feeding needle five times a week for 3 weeks. Atherosclerotic lesions of the aortae were measured, and blood lipoproteins and the expression of molecules related to lipid metabolism in the liver were analysed. We also performed 16S RNA sequencing and a microbiome analysis using faeces. RESULTS: En face bloc preparation of the aortae showed that the PG group had a 1.7-fold increase in atherosclerotic lesions compared with the WD group (p < .01). Serum analyses showed that oral PG infection induced a significant decrease in high-density lipoprotein (HDL) and triglyceride. Western blots of hepatic tissue lysates revealed that PG infection reduced the expression of scavenger receptor class B type 1 (SR-B1) in the liver by 50%. Faecal microbiota analysis revealed that species richness estimates (Chao1, ACE) decreased immediately after PG infection. PG infection also induced a significant decrease in Shannon diversity and an increase in Simpson's indices in the WD-fed mice. PG infection significantly increased the phyla Actinobacteria and Deferribacteres, along with the species Mucispirillum schaedleri and Lactobacillus gasseri, in the mice. The functional study showed that PG infection increased the expression of proteins that function in carbohydrate and glucose metabolism, including phosphotransferase system (PTS) proteins and the GntR family transcriptional regulator. CONCLUSIONS: Oral PG infection promotes atherosclerosis and induces significant metabolic changes, including reduced serum HDL and reduced hepatic SR-B1 and ABCA1 expression, as well as changes in intestinal microbiota. Our study suggests that intestinal dysbiosis accompanies periodontitis and could play a role in atherosclerosis.

Dental students' perception of their educational environment in relation to their satisfaction with dentistry major: a cross-sectional study.

BACKGROUND: Students' perception of their educational environment and satisfaction with their major can reveal the extent of their readiness to practice their profession after graduation. This study aimed to evaluate dental students' perception of their educational environment and satisfaction with their major in dentistry, as well as the relationship between these two factors. METHODS: An online survey was conducted in 2022 among first- to fourth-year students across 11 dental schools in Korea. The Dundee Ready Education Environment Measure (DREEM) and Academic Major Satisfaction Scale (AMSS) were used to measure the students' perception of the educational environment and satisfaction with their major in dentistry, respectively. RESULTS: A total of 539 students participated in the survey (response rate = 18.1%). The overall mean scores of the DREEM and AMSS were 125.03 (maximum score 200) and 22.01 (maximum score 30), respectively. Fourth-year students had the lowest scores in the overall DREEM, DREEM subscales (excluding students' perceptions of atmosphere), and AMSS. The overall DREEM scores and all DREEM subscales showed statistically significant positive and moderate correlations with AMSS (p < 0.001). CONCLUSION: Using the DREEM, we identified areas that need improvement and the academic year (fourth year) that require proactive support. Considering the positive correlation between all DREEM subscales and the AMSS, measures to comprehensively improve the educational environment are needed to improve dental students' satisfaction with their major.

Effects of limb apraxia intervention in patients with stroke: A meta-analysis of randomized controlled trials.

OBJECTIVE: Limb apraxia, a complication of stroke, causes difficulties in performing activities of daily living (ADL). To date, there are no studies on the effectiveness of limb apraxia interventions. We conducted a meta-analysis to assess the effectiveness of limb apraxia interventions in reducing its severity and improving ADL. METHODS: We conducted a search of randomized controlled trials (RCTs) related to limb apraxia till December 2021 using the databases of PubMed, Embase, CINAHL, and the Cochrane Library. We measured the outcome variables in the subgroups of total apraxia (TA), ideational apraxia (IA), ideomotor apraxia (IMA), and ADL. The Physiotherapy Evidence Database (PEDro) scale was used to assess the quality. RESULTS: Five RCTs were selected, and of the 310 participants, 155 were in the experimental and 155 in the control group. A random-effects model was used for the effect size distribution. The limb apraxia intervention methods included gesture and strategy training (three and two studies, respectively). The effect sizes of the outcome variables in the subgroups were small for the TA and IA, with 0.475 (95% confidence interval [CI]: -0.151-1.102; p = 0.137) and 0.289 (95% CI: -0.144-0.722; p = 0.191), respectively. IMA had a medium effect size of 0.731 (95% CI: -0.062-1.525; p = 0.071), not statistically significant, whereas ADL effect size was small and statistically significant, 0.416 (95% CI: 0.159-0.673; p = 0.002). CONCLUSIONS: Gesture and strategy training had statistically significant effects on ADL as limb apraxia interventions. Therefore, the effectiveness of the apraxia interventions needs to be further evaluated through continuous RCTs.

Comparative assessment of marginal and internal gaps of cast-free monolithic zirconia crowns fabricated from 2 intraoral scanners: A prospective, double-blind, randomized clinical trial.

STATEMENT OF PROBLEM: Despite the introduction of intraoral scanners (IOSs) with dual camera triangulation, only a few comparative clinical studies have evaluated their clinical performances in the digital workflow for cast-free restorations. PURPOSE: The purpose of this clinical trial was to assess the clinical efficacy of 2 different technology-based IOSs by evaluating the marginal and internal gaps of cast-free monolithic zirconia crowns fabricated by using a fully digital workflow. MATERIAL AND METHODS: A prospective randomized clinical trial was conducted in 35 participants requiring a single-unit restoration. One crown was fabricated from the scan data obtained with a confocal microscopy-based IOS (Group T), while the other was made with the scan data obtained from an IOS using dual camera triangulation (Group I). A replica technique was used to assess the marginal and internal gaps. The buccolingual and mesiodistal cross-sections were measured, and noninferiority trials were performed. RESULTS: A total of 39 teeth from 35 participants were restored with a single-unit crown. The marginal and axial wall gaps of the crowns in Group I was not inferior to that of the crowns in Group T (upper limit confidence interval [CI] <30). In contrast, the gap of the crowns at the line angle in Group T was inferior to that of the crowns in Group I (lower limit CI <-30). From an occlusal space perspective, the gap of the crowns in Group I was inferior to that of the crowns in Group T (upper limit CI >30). Twenty-five crowns were selected from Group I, and 14 crowns were selected from Group T for definitive placement. CONCLUSIONS: The marginal gap of the crown fabricated by using the scan data obtained from the dual camera triangulation-based IOS was noninferior to that obtained from the confocal microscopy-based IOS and was within the clinically applicable limit.

Effects of incorporating 45S5 bioactive glass into 30% hydrogen peroxide solution on whitening efficacy and enamel surface properties.

OBJECTIVES: This study aimed to evaluate the effects of 30% hydrogen peroxide (HP) solution containing various contents of 45S5 bioactive glass (BAG) on whitening efficacy and enamel surface properties after simulating the clinical bleaching procedure. MATERIALS AND METHODS: A total of 60 bovine enamel specimens discolored with black tea were divided into five groups treated with distilled water (DW), HP, 0.01 wt.% BAG + HP, 1.0 wt.% BAG + HP, and 20.0 wt.% BAG + HP (n = 12). The pH change was observed for 20 min immediately after mixing the experimental solutions, which were applied for 20 min/week, at 37 °C over 21 days. Color, gloss, roughness, microhardness, and micromorphology measurements were conducted before and after bleaching treatment. RESULTS: All groups containing BAG experienced an increase in pH from 3.5 to 5.5 in less than 1 min, and the final pH increased as the BAG content increased. The ΔE of all experimental groups was significantly higher than that of the DW group (p < 0.05), but there were no significant differences between different BAG contents (p > 0.05). Gloss significantly decreased in all experimental groups compared to the DW group, and the increased BAG content had significantly affected the decrease in gloss (p < 0.05). There was no statistical difference in surface roughness (p > 0.05), but hardness increased significantly with BAG content after bleaching treatment (p < 0.05). CONCLUSIONS: HP containing 45S5 BAG showed efficacy in tooth whitening. Also, the pH value of the HP remained acidic near 3.5 for 20 min, while the HP containing the 45S5 BAG showed an increase in pH, which inhibited the demineralization of the enamel surface, and maintained the surface morphology. CLINICAL RELEVANCE: These novel materials are promising candidates to minimize enamel surface damage caused by HP during bleaching procedure in dental clinic.

Effects of 35% hydrogen peroxide solution containing hydrated calcium silicate on enamel surface.

OBJECTIVES: The objectives of this study were to develop a novel bleaching material containing hydrated calcium silicate (hCS) particles and investigate the effects of hCS on the bleaching efficacy, microhardness, and surface morphology of bovine enamel. MATERIALS AND METHODS: To prepare the hCS particles, white Portland cement was mixed with distilled water and ground into a fine powder. The particles in various proportions were then mixed with 35% hydrogen peroxide solution (HP), while HP without hCS was used as a control (HP), and teeth whitening gel was used as a commercial control (CC). Following the thrice application of experimental and control solutions on the discolored bovine enamel surface for 15 min, color change (n = 10), microhardness (n = 10), and micromorphology (n = 2) of the enamel surface were analyzed. RESULTS: The Δ E* of the enamel surface treated with the experimental solution containing hCS was significantly higher than that of the CC, but there were no significant differences between the different hCS contents. The experimental solution containing hCS reduced the percentage of microhardness loss on the enamel surface, and the percentage of microhardness loss significantly decreased as the content of hCS increased (p < 0.05). The erosion pattern was only observed on enamel surfaces treated with HP and CC. CONCLUSIONS: This study suggests that HP containing hCS is effective in bleaching efficacy. In addition, hCS could also minimize the microhardness loss of tooth structure caused by HP and maintain enamel surface morphology. CLINICAL RELEVANCE: This novel bleaching material is promising for inhibiting demineralization and promoting the remineralization of teeth during bleaching treatment in dental clinics.

Effects of postpolymerization conditions on the physical properties, cytotoxicity, and dimensional accuracy of a 3D-printed dental restorative material.

STATEMENT OF PROBLEM: Although the introduction of high-speed 3-dimensional (3D) printing technology has significantly reduced printing time, the time required for postpolymerization is a speed-determining step because of the long wait time. How postpolymerization conditions affect material properties is unclear. PURPOSE: The purpose of this in vitro study was to assess the physical properties, accuracy, and biosafety of a 3D-printed dental restorative material according to postpolymerization conditions. MATERIAL AND METHODS: Specimens were prepared by 3D printing with a digital light processing 3D printer with 1 interim dental material (C&B MFH). All printed specimens underwent a postpolymerization process with 5 different postpolymerization devices and were designated as groups D1 (D102H), FO (Form Cure), LC (LC-3DPrintBox), ME (Medusa), and MP (MP100). The light intensity and temperature of each device were measured, and the Vickers hardness, flexural strength and modulus, degree of conversion (DC), cytotoxicity, and polymerization shrinkage were analyzed. Statistical analyses were conducted with 1-way analysis of variance, the Tukey post hoc test, and regression testing (α=.05). Scanning electron microscopy was used to assess the fracture surface characteristics of the specimens. RESULTS: Light intensity was strongest with the ME device, and the temperature inside the device during postpolymerization showed the highest increase with the LC device and the lowest increase with the D1 device. The LC group specimens showed the highest mean Vickers hardness, and the MP group showed the lowest. The flexural strength was ≥100 MPa in all groups, with a flexural modulus ranging from 1.17 to 1.5 GPa. The DC results were similar to the physical properties test results. The D1, FO, LC, and ME groups all showed ≥70% cell viability, indicating no toxicity. The FO group showed the highest shrinkage rate of 0.52%. CONCLUSIONS: When the light intensity was strong, the surface was sufficiently hard, and toxic substances were not eluted even after a short postpolymerization time, suggesting that light intensity modulation and time management can be used to improve the postpolymerization process.

Time-dependent effects after enamel fluoride application on an acid etching system in orthodontic bracket bonding.

OBJECTIVES: This study investigated the effectiveness of acid etching and bond strength in an orthodontic bonding system in accordance with various time periods after 1.23% acidulated phosphate fluoride (APF) gel applications. MATERIALS AND METHODS: APF gel was applied on the enamel surface of bovine teeth, which were assigned to group F0. The tooth specimens were then immersed in distilled water for 1 (F1), 7 (F7), 14 (F14), 21 (F21) and 28 (F28) days. A group without fluoride pretreatment was a control group. All groups were etched with 35% phosphoric acid and evaluated using a surface hardness tester and scanning electron microscope (SEM). A shear bond strength (SBS) test was performed using a universal testing machine, and the bond failure modes were also examined. RESULTS: After the 1.23% APF gel treatment, the hardness of the acid-etched enamel surface decreased as the immersion period increased. SEM images of the test groups showed etched patterns similar to control group as the immersion period increased. The SBS increased with increasing immersion period, whereas group F21 was not significantly different from the control group. Relatively high adhesive remnant index scores were identified as the ageing period increased. CONCLUSIONS: The present study indicated that in order to obtain suitable bond strength, it is recommended to use an acid etching-based bonding system for the fixation of orthodontic appliances on the enamel surface 21 days after the use of APF gel. CLINICAL RELEVANCE: Fluoride pre-treatment interferes with the acid etching effects on enamel, causing a reduction in the bond strength with orthodontic brackets.

Durable Oral Biofilm Resistance of 3D-Printed Dental Base Polymers Containing Zwitterionic Materials.

Poly(methyl methacralyate) (PMMA) has long been used in dentistry as a base polymer for dentures, and it is recently being used for the 3D printing of dental materials. Despite its many advantages, its susceptibility to microbial colonization remains to be overcome. In this study, the interface between 3D-printed PMMA specimens and oral salivary biofilm was studied following the addition of zwitterionic materials, 2-methacryloyloxyethyl phosphorylcholine (MPC) or sulfobetaine methacrylate (SB). A significant reduction in bacterial and biofilm adhesions was observed following the addition of MPC or SB, owing to their protein-repellent properties, and there were no significant differences between the two test materials. Although the mechanical properties of the tested materials were degraded, the statistical value of the reduction was minimal and all the properties fulfilled the requirements set by the International Standard, ISO 20795-2. Additionally, both the test materials maintained their resistance to biofilm when subjected to hydrothermal fatigue, with no further deterioration of the mechanical properties. Thus, novel 3D-printable PMMA incorporated with MPC or SB shows durable oral salivary biofilm resistance with maintenance of the physical and mechanical properties.

Evaluation of success rate and biomechanical stability of ultraviolet-photofunctionalized miniscrews with short lengths.

INTRODUCTION: The aim of this research was to verify that ultraviolet light (UV)-photofunctionalization improves the success rate and biomechanical stability of miniscrews regardless of length, and to evaluate the comparability of biomechanical stability between UV-photofunctionalized miniscrews with short lengths and untreated miniscrews with conventional lengths. METHODS: Eight male beagles (age, 12-15 months; weight, 10-13 kg) received a total of 64 miniscrews, including 7-mm and 4-mm untreated and UV-photofunctionalized, acid-etched miniscrews with the use of a random block design. The cumulative success rates were examined in all studied groups. The insertion and removal torques and screw mobility were measured. Microcomputed tomographic scans and histomorphometric analyses were performed at 8 weeks postoperatively. RESULTS: The success rates of 7-mm UV-untreated and UV-photofunctionalized miniscrews were 87.5% and 100%, respectively, vs 43.8% for the 4-mm UV-untreated and 4-mm UV-photofunctionalized miniscrews. The rates were significantly different in accordance with the length (P <0.001). There were no differences in the insertion and removal torque and screw mobility between groups according to the length or UV treatment. However, the 4-mm UV-untreated miniscrews yielded a mean bone area ratio of 6.35 ± 7.43%, whereas the 7-mm UV-photofunctionalized miniscrew yielded a mean ratio of 32.17 ± 8.34% (P = 0.037). CONCLUSIONS: The UV-photofunctionalization significantly increased the biomechanical stability and led to increased bone and miniscrew contact area in dogs with miniscrews of the same length. However, the most important factor that affected the success rate of the miniscrew was the length.

Bio-Interactive Zwitterionic Dental Biomaterials for Improving Biofilm Resistance: Characteristics and Applications.

Biofilms are formed on surfaces inside the oral cavity covered by the acquired pellicle and develop into a complex, dynamic, microbial environment. Oral biofilm is a causative factor of dental and periodontal diseases. Accordingly, novel materials that can resist biofilm formation have attracted significant attention. Zwitterionic polymers (ZPs) have unique features that resist protein adhesion and prevent biofilm formation while maintaining biocompatibility. Recent literature has reflected a rapid increase in the application of ZPs as coatings and additives with promising outcomes. In this review, we briefly introduce ZPs and their mechanism of antifouling action, properties of human oral biofilms, and present trends in anti-biofouling, zwitterionic, dental materials. Furthermore, we highlight the existing challenges in the standardization of biofilm research and the future of antifouling, zwitterated, dental materials.

Enhanced Osteogenic Differentiation of Human Mesenchymal Stem Cells on Amine-Functionalized Titanium Using Humidified Ammonia Supplied Nonthermal Atmospheric Pressure Plasma.

The surface molecular chemistry, such as amine functionality, of biomaterials plays a crucial role in the osteogenic activity of relevant cells and tissues during hard tissue regeneration. Here, we examined the possibilities of creating amine functionalities on the surface of titanium by using the nonthermal atmospheric pressure plasma jet (NTAPPJ) method with humidified ammonia, and the effects on human mesenchymal stem cell (hMSC) were investigated. Titanium samples were subjected to NTAPPJ treatments using nitrogen (N-P), air (A-P), or humidified ammonia (NA-P) as the plasma gas, while control (C-P) samples were not subjected to plasma treatment. After plasma exposure, all treatment groups showed increased hydrophilicity and had more attached cells than the C-P. Among the plasma-treated samples, the A-P and NA-P showed surface oxygen functionalities and exhibited greater cell proliferation than the C-P and N-P. The NA-P additionally showed surface amine-related functionalities and exhibited a higher level of alkaline phosphatase activity and osteocalcin expression than the other samples. The results can be explained by increases in fibronectin absorption and focal adhesion kinase gene expression on the NA-P samples. These findings suggest that NTAPPJ technology with humidified ammonia as a gas source has clinical potential for hard tissue generation.

Osteogenic Properties of Novel Methylsulfonylmethane-Coated Hydroxyapatite Scaffold.

Despite numerous advantages of using porous hydroxyapatite (HAp) scaffolds in bone regeneration, the material is limited in terms of osteoinduction. In this study, the porous scaffold made from nanosized HAp was coated with different concentrations of osteoinductive aqueous methylsulfonylmethane (MSM) solution (2.5, 5, 10, and 20%) and the corresponding MH scaffolds were referred to as MH2.5, MH5, MH10, and MH20, respectively. The results showed that all MH scaffolds resulted in burst release of MSM for up to 7 d. Cellular experiments were conducted using MC3T3-E1 preosteoblast cells, which showed no significant difference between the MH2.5 scaffold and the control with respect to the rate of cell proliferation (p > 0.05). There was no significant difference between each group at day 4 for alkaline phosphatase (ALP) activity, though the MH2.5 group showed higher level of activity than other groups at day 10. Calcium deposition, using alizarin red staining, showed that cell mineralization was significantly higher in the MH2.5 scaffold than that in the HAp scaffold (p < 0.0001). This study indicated that the MH2.5 scaffold has potential for both osteoinduction and osteoconduction in bone regeneration.

Occlusion-Fit Three-Dimensional-Printed Zygoma Repositioner.

Reduction malarplasty is utilized to reshape the facial form into an oval shape. However, complications and unfavorable results in reduction malarplasty have been reported. Reoperation of a nonunion malar complex is difficult relative to the achievement of a satisfactory outcome using the intraoral approach with a narrow surgical field because the normal anatomy has been destroyed, and previous surgery may have caused asymmetry. In this situation, computer-aided simulation surgery and surgical guides can serve as effective solutions to overcome the limitations of reoperative malarplasty using the intraoral approach.In this report, the authors present a case with successful treatment outcomes for a nonunion malar complex using a three-dimensional-printed zygoma repositioner.

Effects of Resistive Jaw-Opening Exercise with Elastic Bands on Suprahyoid Muscle Activation in Normal Subjects.

OBJECTIVE: The effect of a resistive jaw-opening exercise using an elastic band on suprahyoid muscle activity and tongue strength was examined in healthy volunteers. METHODS: Twenty-one adults wore an elastic loop around their head and mandible. To prescribe the appropriate elastic band resistance, the 10-repetition maximum (10 RM) was measured among 4 bands at baseline. Band loops, starting with the highest resistance value band, were sequentially applied to determine the suitability for 10 RM. During the exercise, the participants were required to open their jaw maximally and maintain the position for 10 s; then, they rested for 10 s. This procedure was repeated for 20 min, 3 days per week for 8 weeks to test suprahyoid muscle activation during effortful swallowing; isometric tongue pressures of the tongue tip and base at baseline, after 4, and after 8 weeks of training were measured. RESULTS: Peak suprahyoid muscle activation amplitudes during effortful swallow and isometric pressures at the tongue tip significantly increased after 8 weeks. CONCLUSION: The 8-week resistive jaw-opening exercise significantly improved strength of the suprahyoid muscle and tongue pressures in healthy subjects. These positive results warrant further investigation of the therapeutic effects and feasibility of this resistive exercise.

Occlusion-Fit V-Line Guide and Gooseneck Saw for Safe and Accurate Mandibuloplasty in Asians.

BACKGROUND: A slender or slim face with narrow facial features is considered esthetically appealing in Asian people. Plastic surgery to obtain an oval face, called a 'V-line,' is popular among young people. MATERIALS AND METHODS: A total of 20 Korean patients were included in this study. The patients underwent mandibular anguloplasty with three-dimensional computer-aided design and manufacturing surgical guides that were accurately fitted to the upper and lower teeth, allowing for precise replication of a virtual surgery during a real surgical procedure. RESULTS: There were no significant complications, including severe bleeding, facial nerve injury, or airway obstruction. All patients were satisfied with the esthetic and functional results, except for one who was neutral toward the result. The mean satisfaction score was 4.75, which was between 'satisfied' and 'very satisfied.' CONCLUSION: The V-line guide and gooseneck saw allowed for safe and fast resection of bone in the mandibular angle area. This technique provides consistent results during surgery as well as minimizing surgical complications. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors http://www.springer.com/00266 .

Simultaneous Bimaxillary Surgery and Mandibular Reconstruction With a 3-Dimensional Printed Titanium Implant Fabricated by Electron Beam Melting: A Preliminary Mechanical Testing of the Printed Mandible.

A woman presented with a long history of mandibular defects posterior to the left lower first premolar caused by inadequate reconstruction after removal of a tumor on the left side of the mandible. In the frontal view, extreme facial asymmetry was apparent. The dental midline of the mandible was deviated 10 mm to the left compared with the dental midline of the maxilla, and all maxillary teeth were inclined to the left owing to dental compensation. There was an 8-mm maxillary occlusal cant relative to the maxillary first molar. Bimaxillary surgery using computer-assisted designed and computer-assisted manufactured devices without an intermediate occlusal splint was performed to align the maxilla and mandible at the correct position, and reconstructive surgery for the mandible using a 3-dimensional printed titanium mandible was concurrently performed. In particular, during the virtual mandible design, 2 abutments that enabled the prosthetic restoration were included in the mandible using a computer-assisted design program. This report describes the successful functional and esthetic reconstruction of the mandible using electron beam melting technology, an alternative technique for reconstruction of mandibles that did not undergo radiation therapy.

Titanium-Silver Alloy Miniplates for Mandibular Fixation: In Vitro and In Vivo Study.

PURPOSE: Titanium (Ti) alloys have received considerable attention as materials for oral and maxillofacial surgery, which require high mechanical strength, osteosynthesis, and biocompatibility. The objective was to implant miniplates fabricated from commercially pure Ti (CP Ti) and newly developed Ti-silver (Ag) alloy in fractured mandibles of adult dogs after preliminary mechanical and biological characterization. MATERIALS AND METHODS: The surface characteristics, biocompatibility, and pre-osteoblast adhesion and proliferation of CP Ti (grade 3) and Ti-Ag (2 at% Ag) alloys were evaluated. Next, the bending strength of 6- and 8-hole miniplates fabricated from CP Ti and Ti-Ag was compared according to ISO (International Organization for Standardization) 9585. Six-hole miniplates were implanted for 12 weeks in fractured mandibles of adult dogs. The Ag ion concentration in each alloy and implanted bone block with soft tissue was measured by inductively coupled plasma mass spectroscopy after euthanasia according to ISO 10993-12. RESULTS: Precipitated Ag was detected in Ti-Ag by alpha- and beta-phase Ti in x-ray powder diffraction. The biocompatibility with pre-osteoblasts of Ti-Ag and CP Ti was comparable in terms of cytotoxicity, cell adhesion, and proliferation (P > .05). Ti-Ag miniplates had up to 3-fold greater bending strength than CP Ti miniplates (P < .05). An in vivo study showed that CP Ti and Ti-Ag miniplates had comparable soft and hard tissue regeneration ability (P > .05). Ag ions were detected in Ti-Ag alloys and applied mandible blocks. CONCLUSIONS: The results of this study suggest that Ti-Ag alloys can be used to produce miniplates with high mechanical properties, as well as considerable biocompatibility, osteosynthesis ability, and Ag ion-release properties. Further studies, including preclinical investigations, are required to enable clinical use of Ti-Ag bone plates.

Non-thermal atmospheric pressure plasma increased mRNA expression of growth factors in human gingival fibroblasts.

OBJECTIVES: The aim of this in vitro study was to investigate the effects of a non-thermal atmospheric pressure plasma jet (NTAPPJ) on the cellular activity of human gingival fibroblasts (HGF) for possible non-surgical application of it during gingival wound healing. MATERIALS AND METHODS: HGF cells were exposed with NTAPPJ for 1, 2, and 4 min and were investigated for cellular attachment, cell viability, morphology of attached cells, proliferation rate, and messenger ribonucleic acid (mRNA) expression of various growth factors. Also, scavengers for chemicals produced by NTAPPJ were used to identify the chemical species responsible for the effects. RESULTS: There was no significant change in the number of HGF cells attached or their proliferation following NTAPPJ exposure. Also, high cell viability resulted from exposure of all of HGF cells to NTAPPJ for 1, 2, and 4 min. However, cells were more stretched while the mRNA expressions of transforming growth factor and vascular endothelial growth factor were significantly increased following NTAPPJ exposure. Additionally, the scavenger test showed that nitric oxide is likely to be the chemical responsible for an increase of cellular activity. CONCLUSION: The results demonstrated that the NTAPPJ increased mRNA expressions of growth factors in human gingival fibroblasts. CLINICAL RELEVANCE: Application of NTAPPJ would be useful in gingival wound healing in clinics though additional studies confirming the effects would be needed.