Comparison of digital and conventional methods of fit evaluation of partial removable dental prosthesis frameworks fabricated by selective laser melting.

STATEMENT OF PROBLEM: Three-dimensional (3D) printing technology may improve the fit of partial removable dental prosthesis frameworks made by selective laser melting. Conventionally, the gaps between definitive casts and prostheses are evaluated by using clinical replicas, but digital evaluations may provide a better alternative. PURPOSE: The purpose of this in vitro study was to compare digital and conventional methods for evaluating the fit of partial removable dental prosthesis frameworks made by selective laser melting. MATERIAL AND METHODS: A printed resin definitive cast representing a Kennedy class II modification 2 design with 5 reference markers was made from a dentiform cast. Twelve cobalt-chromium partial removable dental prosthesis frameworks were fabricated by selective laser melting on this definitive cast with a digital design software program. The gaps between the frameworks and the cast were assessed by using the clinical replica method with a silicone impression material and measuring the thickness at each marker with calipers. Digital casts of each framework and the definitive cast were scanned and then registered with the CloudCompare software program to measure 3D gaps at the 5 reference markers and 3 occlusal rests. The results were analyzed individually for each technique by 1-way analysis of variance (ANOVA) with post hoc Bonferroni tests (α=.05). RESULTS: For clinical registration, the mean gap between the frameworks and definitive cast was 13.9 ±7.6 µm. For digital registration, the root mean square gap was 70.7 ±24.2 µm. Statistically significant differences among the gaps for different markers were found for both approaches (P<.05). There were no significant differences among the gaps between the different frameworks. In both situations, the gap measurements were below the 300-µm clinically acceptable standard. CONCLUSIONS: Both registration methods determined whether the fit of a framework fabricated by selective laser melting was within a clinically acceptable standard. The differences in the values produced most likely arose from the different registration methods.

The effect of overnight storage conditions on complete denture colonization by Candida albicans and dimensional stability: A systematic review.

STATEMENT OF PROBLEM: Overnight removal of complete dentures is recommended to reduce the incidence of denture stomatitis. The effect of overnight storage conditions is unclear. PURPOSE: The purpose of this systematic review was to assess the effect of overnight storage conditions on complete denture colonization by Candida albicans and to explore the effect of overnight storage conditions on the dimensional stability of complete dentures. MATERIAL AND METHODS: Two electronic databases were searched through to November 2018. The terms "denture*", "dental prosthes*", "acrylic resin*", "storage", "nighttime", "overnight", "wet", "dry", "water*", and "solution" were chosen. Articles meeting the inclusion criteria were selected. For both research questions, studies that did not store the dentures overnight or for a minimum of 8 hours were excluded. For the primary research question, studies that were not randomized controlled studies or comparative studies were excluded. RESULTS: The database search strategy resulted in a total of 159 potential studies. After screening titles and abstracts and applying the inclusion and exclusion criteria, 6 studies were retrieved for a full-text assessment. Hand searching was also performed. Four studies were included in the systematic review for the primary research question. Three studies were included for the secondary research question. A meta-analysis could not be performed because of variation in study design. CONCLUSIONS: Cleaning of dentures before overnight storage helps reduce C. albicans colonization. If the dentures are not cleaned, the use of an alkaline peroxide-based cleaning tablet should be considered. Alternately, overnight dry storage is an option for reducing C. albicans colonization, with clinically insignificant changes to the dimensions of the complete denture. Storing dentures in water alone may promote C. albicans colonization.

Clinical remounting of complete dentures: A systematic review.

STATEMENT OF PROBLEM: A recent trend has been to reduce the procedural complexity of complete denture fabrication. Whether the clinical remount step is necessary is unclear. PURPOSE: The purpose of this systematic review was to assess the relevance of the clinical remount procedure on complete denture outcomes. MATERIAL AND METHODS: Five electronic databases were searched through to May 2018. The terms "denture*", "dental prosthes*", "equilibrat*", and "remount*" were chosen. The titles and abstracts were screened, and those which met the inclusion criteria were selected for full-text assessment. Studies that only performed the laboratory remount or were not randomized controlled studies were excluded. RESULTS: After duplicate removal, the database search strategy resulted in a total of 226 potential studies. After the titles and abstracts had been screened and the inclusion and exclusion criteria applied, 10 studies were retrieved for full-text assessment. Four randomized controlled clinical studies were included in the systematic review. A meta-analysis could not be performed because of variation in outcome measures after the clinical remount. CONCLUSIONS: A clinical remount for complete dentures is recommended on delivery to reduce clinically observed areas of discomfort and reduce the number of recall appointments. The development of a reliable and valid patient satisfaction questionnaire is necessary to determine conclusively whether the clinical remount also improves patient-perceived satisfaction and mastication.

Marginal Fit and Internal Adaptation of Monolithic Zirconia 3-Unit Fixed Dental Prosthesis: In Vitro Study.

PURPOSE: To compare the marginal and internal fit of monolithic zirconia (MZ) 3-unit fixed dental prostheses (FDPs) fabricated using two CAD/CAM workflows: full-chairside (FCH) and lab (LAB). MATERIALS AND METHODS: The right maxillary first premolar and first molar were prepared for MZ 3-unit FDPs on a typodont. CEREC Primescan digitized the typodont model 15 Omes. A total of 30 FDPs was fabricated using two processes: FCH (n = 15) and LAB (n = 15). FCH and LAB FDPs were designed using CEREC SW 4.5.1 and Exocad and milled using CEREC MC X and Zirkonzhan 600/V3, respectively. A fast-sintering protocol was used in both groups. A dual-scan technique was used to assess the cement space at the occlusal surface (OC), axial wall (AX), and margin (MA). Statistical analysis of the results was performed using univariate ANOVA with Scheff. post hoc test (a = .05). RESULTS: Measurements in the FCH and LAB groups were within the clinically acceptable marginal and internal fit. The fit of FCH FDPs at MA, AX, and OC was 77.50 ± 29.99 µm, 99.67 ± 21.58 µm, and 150.03 ± 30.78 µm, respectively. The fit of LAB FDPs at MA, AX, and OC was 100.27 ± 27.06 µm, 116.53 ± 17.90 µm, and 142.30 ± 19.00 µm, respectively. The difference between the two groups was not statistically significant. CONCLUSIONS: MZ 3-unit FDPs fabricated using FCH have clinically acceptable marginal and internal fit. This result verifies the ability of FCH workflow to fabricate MZ mulOunit FDPs in a single visit.

Modification of human BMSC with nanoparticles of polymeric biomaterials and plasmid DNA for BMP-2 secretion.

BACKGROUND: Genetic modification of human bone marrow stem cells (hBMSCs) before administration to a patient is emerging as a viable approach to creating tailored cells that perform effectively in a clinical setting. To this end, safe delivery systems are needed that can package therapeutic genes into nanoparticles for cellular delivery. METHODS: We evaluated different plasmids on gene expression and compared the effective plasmids directly in hBMSCs. Then, we evaluated the transfection efficiencies of the polymeric carriers linoleic acid-substituted polyethylenimine (PEI-LA), polyethylenimine (PEI)-25, and PEI-2 using flow cytometry. We used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide to compare the toxicity of PEI-LA and PEI-25 on hBMSCs. We further assessed bone morphogenetic protein-2 (BMP-2) secretion and the osteogenic activity of hBMSCs transfected with the polymeric (PEI-LA and PEI-25) gWIZ-BMP-2 complex. RESULTS: Unlike the transformed cells that gave robust (>50%) transfection, only a few percent (<10%) of hBMSCs was transfected by the developed nanoparticles in culture. The plasmid DNA design was critical for expression of the transgene product, with the choice of the right promoter clearly enhancing the efficiency of transgene expression. Using the in-house designed PEI-LA, hBMSCs secreted BMP-2 in culture (~4 ng BMP-2/10(6) cells/d), which indicates the feasibility of using PEI-LA as a delivery system. Furthermore, we demonstrated an increased osteogenic activity in vitro for hBMSCs transfected with the PEI-LA containing the BMP-2 expression system. CONCLUSIONS: These results provide encouraging evidence for the potential use of a low toxic PEI-LA to genetically modify hBMSC.

Validation of three-dimensional facial imaging captured with smartphone-based photogrammetry application in comparison to stereophotogrammetry system.

Statement of problem: The development of facial scanners has improved capabilities to create three-dimensional (3D) virtual patients for accurate facial and smile analysis. However, most of these scanners are expensive, stationary and involve a significant clinical footprint. The use of the Apple iPhone and its integrated "TrueDepth" near-infrared (NIR) scanner combined with an image processing application (app) offers the potential to capture and analyze the unique 3D nature of the face; the accuracy and reliability of which are yet to be established for use in clinical dentistry. Purpose: This study was designed to validate both the trueness and precision of the iPhone 11 Pro smartphone TrueDepth NIR scanner in conjunction with the Bellus3D Face app in capturing 3D facial images in a sample of adult participants in comparison to the conventional 3dMDface stereophotogrammetry system. Material and methods: Twenty-nine adult participants were prospectively recruited. Eighteen soft tissue landmarks were marked on each participant's face before imaging. 3D facial images were captured using a 3dMDface system and the Apple iPhone TrueDepth NIR scanner combined with the Bellus3D Face app respectively. The best fit of each experimental model to the 3dMD scan was analyzed using Geomagic Control X software. The root mean square (RMS) was used to measure the "trueness" as the absolute deviation of each TrueDepth scan from the reference 3dMD image. Individual facial landmark deviations were also assessed to evaluate the reliability in different craniofacial regions. The "precision" of the smartphone was tested by taking 10 consecutive scans of the same subject and comparing those to the reference scan. Intra-observer and inter-observer reliabilities were assessed using the intra-class correlation coefficient (ICC). Results: Relative to the 3dMDface system, the mean RMS difference of the iPhone/Bellus3D app was 0.86 ± 0.31 mm. 97% of all the landmarks were within 2 mm of error compared with the reference data. The ICC for intra-observer reproducibility or precision of the iPhone/Bellus3D app was 0.96, which was classified as excellent. The ICC for inter-observer reliability was 0.84, which was classified as good. Conclusions: These results suggest that 3D facial images acquired with this system, the iPhone TrueDepth NIR camera in conjunction with the Bellus3D Face app, are clinically accurate and reliable. Judicious use is advised in clinical situations that require high degrees of detail due to a lack of image resolution and a longer acquisition time. Generally, this system possesses the potential to serve as a practical alternative to conventional stereophotogrammetry systems for use in a clinical setting due to its accessibility and relative ease of use and further research is planned to appraise its updated clinical use.

Theory-Guided Remote Cooperative Learning-Based Preventive Dental Education as Part of the School Curriculum.

BACKGROUND: Oral health is fundamental to overall well-being. As teens are at high risk for tooth decay, we require a unique approach to motivate them to maintain oral health. METHODS: Sixty-four adolescents (10-13 years) were recruited from 2 schools. Oral health education was based on cooperative learning guided by the social determination theory (SDT) principles. Students' oral health knowledge and oral self-care skills were assessed at baseline (before education), 3 weeks, and 6 months after the education. RESULTS: Complete data were available for 51 students (follow-up rate 79.7%). There were significant (p < 0.001) changes in the mean (SD) toothbrushing score from 10.1 (±6.3) (baseline) to 26.5 (±6.0) (follow-up 1) and to 28.1 (±5.3) (follow-up 2). The mean (SD) tooth brushing time significantly (p < 0.001) increased from the baseline of 84.0 (±43.5) to the first follow-up to 107.0 (±39.8) and to 102.3 (±33.1) at the second follow-up. The mean (SD) diet knowledge scores significantly (p < 0.001) increased from 8.2 (±2.1) at the baseline to 10.2 (±2.7) at the first follow-up and remained the same at the second follow-up. CONCLUSION: Social determination theory-guided cooperative learning was efficient in improving student oral health-related knowledge and oral self-care skills, and this improvement was maintained for 6 months after the discontinued education.

Osteogenic differentiation of human mesenchymal stem cells cultured with dexamethasone, vitamin D3, basic fibroblast growth factor, and bone morphogenetic protein-2.

PURPOSE: Human mesenchymal stem cells (hMSCs) are pursued for cell-based therapies of bone defects. Successful use of hMSCs will require them to be osteogenically differentiated before transplantation. This study was intended to determine the optimal combination(s) of supplements needed for inducing osteogenesis in hMSCs. METHODS: The hMSCs were cultured with combinations of ß-glycerophosphate, dexamethasone (Dex), vitamin D3 (Vit-D3), basic fibroblast growth factor (bFGF), and bone morphogenetic protein-2 (BMP-2) to assess cell growth and osteogenesis. Osteogenic responses of the supplements were evaluated by alkaline phosphatase (ALP) activity, mineralization, and gene expression of ALP, Runx2, bone sialoprotein, and osteonectin. Adipogenesis was characterized based on Oil Red O staining, gene expression of peroxisome proliferator-activated receptor γ2, and adipocyte protein-2. RESULTS: Dex was found to be essential for mineralization of hMSCs. Cultures treated with Dex (100 nM), Vit-D3 (10/50 nM), and BMP-2 (500 ng/mL) demonstrated maximal calcification and up-regulation of ALP and bone sialoprotein expression. However, adipogenesis was up-regulated in parallel with osteogenesis in these cultures, as evident by the presence of lipid droplets and significant up-regulation of peroxisome proliferator-activated receptor γ2 and adipocyte protein-2 expression. An optimal condition was obtained at Dex (10 nM) and BMP-2 (500 ng/mL) for mineralization without increasing adipogenesis-related markers. The bFGF mitigated osteogenesis and enhanced adipogenesis. Vit-D3 appears essential for calcification only in the presence of bFGF. CONCLUSION: Treatment of hMSCs with appropriate supplements at optimal doses results in robust osteogenic differentiation with minimal adipogenesis. These findings could be used in the cultivation of hMSCs for cell-based strategies for bone regeneration.

Accuracy and precision of using partial-mouth recordings to study the prevalence, extent and risk associations of untreated periodontitis.

To study the accuracy and precision of estimating the prevalence, extent and associated risks of untreated periodontitis using partial-mouth recording protocols (PRPs) Methods: A purposive sample of 431 individuals who had never been treated for periodontal disease was recruited from screening clinics at the King Saud bin Abdul-Aziz University for Health Sciences. Data were collected using questionnaires and clinical examinations. The prevalence, extent and risk associations of periodontitis were evaluated. Three PRPs were compared to full-mouth recordings (FRPs) in terms of the sensitivity, specificity, predictive values, and absolute bias. Results: The prevalence of periodontitis was estimated with the highest accuracy and precision by examinations of the full mouth at the mesiobuccal and distolingual sites (FM)MB-DL, followed by random half-mouth (RHM) recordings. The extent of periodontitis was estimated with high precision using all the PRPs, and the absolute bias ranged from -0.6 to -2.3. The absolute bias indicated by OR for risk associations was small for the three PRPs and ranged from -0.8 to 0.8. Conclusion: (FM)MB-DL and RHM were the PRPs with moderate to high levels of accuracy and precision for estimating the prevalence and risk associations of periodontitis. The extent of periodontitis was estimated with high precision using all three PRPs. The results of this study showed that the magnitude and direction of bias were associated with the severity of periodontitis, the selected PRPs and the magnitude of the risk associations.

Periodontal disease prevalence, extent, and risk associations in untreated individuals.

OBJECTIVES: to examine the prevalence, extent, and risk associations of untreated periodontitis. MATERIALS AND METHODS: A purposive sample of subjects who were never treated for periodontal conditions was clinically examined after collecting information about their sociodemographic characteristics, medical conditions, oral health behaviors, perceived stress, and perceived social support. RESULTS: A total of 431 subjects were recruited (response rate, 97.0%), and their mean age (SD) was 35.4 (13.3) years. Overall, high plaque levels were observed in all untreated individuals. The prevalence of periodontitis and severe (stage III/IV) periodontitis using the American Academy of Periodontology and European Federation of Periodontology (AAP/EFP) classification were 85.4% and 48.5%, respectively. The prevalence of moderate-severe and severe periodontitis using the definitions of the Centers for Disease Control and Prevention (CDC) and AAP were 78.4% and 31.1%, respectively. The extent of periodontitis expressed as mean% of clinical attachment loss (CAL) ≥ 3 mm and CAL ≥ 5 mm were 34.9% and 14.4%, respectively, while the mean% of a periodontal probing depth (PPD) ≥4 mm and PPD ≥6 mm were 22.0% and 9.2%, respectively. Risk determinants associated with AAP/EFP periodontitis after the adjustment for other variables were age ≥35 years (odds ratio [OR] = 11.5) and lower income (OR = 2.5). Adjusted risk associations with stage II/IV periodontitis included age ≥35 years (OR = 8.2), males (OR = 2.5), lower income (OR = 2.3), and lower perceived stress (OR = 2.0). Adjusted risk associations with CDC/AAP moderate-severe periodontitis included age ≥35 years (OR = 12.0), lower income (OR = 2.1), and current cigarette smoking (OR = 4.2). Adjusted risk associations with CDC/AAP severe periodontitis included age ≥35 years (OR = 4.5), males (OR = 1.9), lower education (OR = 2.0), lower income (OR = 1.7), uncontrolled diabetes mellitus (OR = 2.0), and current cigarette smoking (OR = 2.3). CONCLUSIONS: The prevalence and extent of periodontitis were high in untreated subjects. Risk associations with untreated periodontitis included age ≥35 years, males, lower income, lower education, current cigarette smoking, uncontrolled diabetes mellitus, and lower perceived stress.

Effect of Photobiomodulation on Structure and Function of Extracellular Vesicle Secreted from Mesenchymal Stem Cells.

The current study intended to evaluate the effect of photobiomodulation on the morphology and function of EVs secreted from mesenchymal stem cells (MSCs) derived from periodontal ligament (PDL) and the adipose tissue (ADSCs) (from buccal fat pad) in vitro. These cells were irradiated at 660 nm or kept in dark as control. EVs were then isolated from each group using ultracentrifugation. EVs were defined by flow cytometry and Western blot. Electron microscopy (SEM) was used to study the morphology of EVs. Then, MTT and wound-healing scratch assays were applied to compare the cell survival and migration of human dermal fibroblast (HDF) cells treated with the EVs obtained from the four groups. According to SEM images, isolated EV were round and cup-shaped in all groups showing no destructive effects of laser irradiation on EV morphology. MTT test results revealed a statistically significant difference between the HDF cells treated with different EV groups from hPDLSCs-Dark in comparison with control (0 µg/mL) (P < 0.05) and treated with exosome from hPDLSCs-Irradiation cells compared with dark group (P < 0.05). However, scratch wound-healing assay did not show a significant difference between various groups (P ˃ 0.05). Further studies with different irradiation protocols are recommended to find an optimal strategy.

Management of a Class I malocclusion with traumatically avulsed maxillary central and lateral incisors.

This case report describes orthodontic space closure for managing an avulsed maxillary central incisor and a lateral incisor in a growing girl with a Class I deep bite malocclusion with moderate lower and mild upper crowding. The treatment approach moved a central incisor across the midline and substituted a lateral incisor for a central incisor, in combination with canine substitution. Veneers on all maxillary anterior teeth attained acceptable esthetics. The right central incisor was moved to serve as the avulsed left central incisor. The right lateral incisor was moved to the position of the right central incisor and restored. The canines on both sides were substituted as lateral incisors; the posterior occlusion was left in Class II. Mesialization of central and lateral incisors with prosthetic rehabilitation is an acceptable treatment option.

Cleft palate reconstruction using collagen and nanofiber scaffold incorporating bone morphogenetic protein in rats.

BACKGROUND: Absorbable collagen sponge (ACS) loaded with bone morphogenetic protein-2 (BMP-2) is approved for selected clinical applications; however, burst release limits its widespread use. Therefore, nanofiber (NF)-based scaffold with ACS backbone was developed to sustain release of loaded BMP-2 to improve the outcomes of bone grafting in a rodent model of cleft palate. METHODS: BMP-2 was loaded on ACS scaffold and then NF hydrogel with different densities (1-2%) was added to sustain the BMP-2 release. The release profiles of BMP-2 from constructs with different NF densities were evaluated in vitro to explore the optimum NF density that could recapitulate physiological bone healing process. Subsequently, scaffold with the appropriate NF density was implanted into a rodent model of cleft palate. Wistar rats, with surgically induced maxillary cleft defects, were then assigned to one of the following groups (n=6/group): no scaffold (control), ACS, ACS+BMP-2, NF+ACS, and NF+ACS+BMP-2. Micro-computed tomography (µCT) was utilized to evaluate percent bone filling (%BF) at defect site as well as changes in anteroposterior and transverse dimensions of the maxilla at weeks 0, 4, and 8. Histological assessment of bone healing was performed at week 8. RESULTS: In vitro release experiments showed that scaffolds containing 2% NF exhibited a release profile conducive to the natural stages of bone healing and, hence, it was utilized for subsequent in vivo studies. Bone healing occurred at the defect margins leaving a central bone void in the control, ACS, and NF+ACS groups over the 8-week study period. BMP-2-treated groups demonstrated higher %BF as compared with other groups at week 8 (p<0.05). Whereas the NF+ACS+BMP-2 group showed bone bridging of the defect as early as 4 weeks, which was not evident in ACS+BMP-2 group. In all groups, bone grafts did not disrupt anteroposterior and transverse growth of maxilla. Based on histological evaluations together with µCT data, NF+ACS+BMP-2 treatment resulted in clinically significant and consistent bone healing throughout the implanted scaffold when compared with the ACS+BMP-2 group. CONCLUSION: NF+ACS+BMP-2 constructs exhibited osteoinductive properties together with preparation simplicity, which makes it a novel approach for BMP-2 delivery for cleft palate reconstruction.

Reliable critical sized defect rodent model for cleft palate research.

BACKGROUND: Suitable animal models are necessary to test the efficacy of new bone grafting therapies in cleft palate surgery. Rodent models of cleft palate are available but have limitations. This study compared and modified mid-palate cleft (MPC) and alveolar cleft (AC) models to determine the most reliable and reproducible model for bone grafting studies. METHODS: Published MPC model (9 × 5 × 3 mm(3)) lacked sufficient information for tested rats. Our initial studies utilizing AC model (7 × 4 × 3 mm(3)) in 8 and 16 weeks old Sprague Dawley (SD) rats revealed injury to adjacent structures. After comparing anteroposterior and transverse maxillary dimensions in 16 weeks old SD and Wistar rats, virtual planning was performed to modify MPC and AC defects dimensions, taking the adjacent structures into consideration. Modified MPC (7 × 2.5 × 1 mm(3)) and AC (5 × 2.5 × 1 mm(3)) defects were employed in 16 weeks old Wistar rats and healing was monitored by micro-computed tomography and histology. RESULTS: Maxillary dimensions in SD and Wistar rats were not significantly different. Preoperative virtual planning enhanced postoperative surgical outcomes. Bone healing occurred at defect margin leaving central bone void confirming the critical size nature of the modified MPC and AC defects. CONCLUSIONS: Presented modifications for MPC and AC models created clinically relevant and reproducible defects.

Bisphosphonate-decorated lipid nanoparticles designed as drug carriers for bone diseases.

A conjugate of distearoylphosphoethanolamine-polyethylene glycol with 2-(3-mercaptopropylsulfanyl)-ethyl-1,1-bisphosphonic acid (thiolBP) was synthesized and incorporated into micelles and liposomes to create mineral-binding nanocarriers for therapeutic agents. The micelles and liposomes were used to encapsulate the anticancer drug doxorubicin (DOX) and a model protein lysozyme (LYZ) by using lipid film hydration (LFH) and reverse-phase evaporation vesicle (REV) methods. The results indicated that the micelles and LFH-derived liposomes were better at DOX loading than the REV-derived liposomes, while the REV method was preferable for encapsulating LYZ. The affinity of the micellar and liposomal formulations to hydroxyapatite (HA) was assessed in vitro, and the results indicated that all the thiolBP-incorporated nanocarriers had stronger HA affinity than their counterparts without thiolBP. The thiolBP-decorated liposomes also displayed a strong binding to a collagen/HA composite scaffold in vitro. More importantly, thiolBP-decorated liposomes gave increased retention in the collagen/HA scaffolds after subcutaneously implantation in rats. The designed liposomes were able to entrap the bone morphogenetic protein-2 in a bioactive form, indicating that the proposed nanocarriers could deliver bioactive factors locally in mineralized scaffolds for bone tissue engineering.

In vitro osteogenic induction of human gingival fibroblasts for bone regeneration.

BACKGROUND AND OBJECTIVE: Periodontitis is an inflammatory disease causing bone loss, and is a primary cause of tooth loss. Gingival fibroblasts are readily available with minimal donor site morbidity and may be ideal for tissue engineering efforts in regenerating lost alveolar bone. Dexamethasone (Dex) is commonly employed for in vitro osteogenic induction of a variety of cells, but its effect on human gingival fibroblasts (HGF) is still controversial. Therefore, the aim of our study was to investigate the osteogenic differentiation of HGF following Dex treatment. METHODS: Cultured HGFs were exposed to osteogenic medium containing a wide range of Dex concentrations (0.01-10 µM). The osteogenic phenotype was assessed based on changes in alkaline phosphatase (ALP) activity, the mRNA expression of selected extracellular matrix proteins critical for mineralization and the extent of extracellular mineralization (Von Kossa staining and Ca-content). RESULTS: All assays showed a consistent and maximal osteogenic effect of Dex on HGF at 0.1 and 0.5 µM (weeks 3 and 4), as evidenced by significant osteopontin and osteocalcin expression and mineralization. Longer cultures (week 4) also yielded positive osteogenic effect of Dex at 0.01 µM. Moreover, ALP activity was significantly stimulated at 0.1 and 0.5 µM Dex initially after one week, but ALP was subsequently reduced under Dex. Higher Dex concentrations caused down regulation of osteogenic effects observed at the optimal (0.1-0.5 µM) concentrations. CONCLUSION: Under appropriate osteogenic conditioning, Dex treated HGFs could be a potential source of cells for cell-based therapy for periodontal bone regeneration.

Anabolic effects of low-intensity pulsed ultrasound on human gingival fibroblasts.

OBJECTIVE: Low-intensity pulsed ultrasound (LIPUS) demonstrated anabolic effects on cementoblasts, odontoblasts, and periodontal ligament cells. However, LIPUS effect on human gingival fibroblasts (HGF) remains to be investigated. Therefore, we evaluated the in vitro effects of LIPUS on HGF proliferation and differentiation to test its feasibility for periodontal therapy. DESIGN: LIPUS treatment (1.5MHz, 30mW/cm(2)) was applied to HGF in the experimental groups after 24-h of culture (5 or 10min/day for 28 days) and omitted in the control. Changes in HGF activities were evaluated in response to LIPUS treatment in dose-dependent (5 and 10min) and time-dependent (weeks 1-4) manner. The effects of LIPUS on HGF cell viability (MTT), proliferation (total DNA content and growth pattern), alkaline phosphatase (ALP) activity, and gene expression by reverse-transcriptase polymerase chain reaction (RT-PCR) were determined. RESULTS: Cell viability remained unchanged after LIPUS treatment during the 4 weeks of treatment as compared to the untreated control group which ensured a safe biological response. Both LIPUS treatments (5-10min/day) did not yield any significant changes in the proliferation, and expression of proliferating cell nuclear antigen (PCNA) and collagen-I (COL-I). Conversely, LIPUS treatment enhanced osteogenic differentiation potential of HGF as determined by significant up-regulation of specific ALP activity and osteopontin (OPN) expression, with optimum effect following 3 weeks of 5min/day LIPUS treatment. CONCLUSION: LIPUS treatment at 30mW/cm(2) selectively enhanced HGF differentiation but not proliferation. The ability of LIPUS to enhance HGF differentiation is promising for its application in cell-based periodontal therapy.