Odontology

Correction to: Internal and marginal adaptation of high-viscosity bulk-fill composites in class II cavities placed with different adhesive strategies In the original publication of the article the paragraph “The four resin-based composites…” appearing below the “Materials and methods” section is incomplete. The correct paragraph is provided in this correction below.

ADAM28 dramatically regulates the biological features of human gingival fibroblasts Abstract This study was to explore the effects of a disintegrin and metalloproteinase 28 (ADAM28) on the proliferation, differentiation, and apoptosis of human gingival fibroblasts (HGFs) and probable mechanism. After ADAM28 antisense oligodeoxynucleotide (AS-ODN) and sense oligodeoxynucleotide (S-ODN) were transfected into HGFs by Lipofectamine 2000, respectively, the expression discrepancies of ADAM28 among various groups were evaluated by reverse transcription-polymerase chain reaction (RT-PCR) and Western-blotting. Methabenzthiazuron (MTT) and cell-cycle assays were used to test the HGFs proliferation activity. Annexin V fluorescein isothiocyanate (FITC)/propidium iodide (PI) and alkaline phosphatase (ALP) analysis were performed separately to measure apoptosis and the cytodifferentiation standard. Immunocytochemistry and Western-blotting were carried out to determine the influence of ADAM28 AS-ODN on HGFs expressing core binding factor α1 (Cbfα1), cementum protein 1 (CEMP1), osteopontin (OPN) and dentin matrix protein 1 (DMP1). The AS-ODN group displayed the lowest expression level in HGFs, meanwhile the ADAM28 S-ODN group showed the highest. Furthermore, blocking of ADAM28 could inhibit the proliferation of HGFs, enhance HGFs differentiation and induce apoptosis of HGFs. Whereas, overexpression of ADAM28 generated the opposite effects and inhibited apoptosis. ADAM28 AS-ODN was able to notably suppress the expressions of Cbfα1 and CEMP1, and ADAM28 had positive correlations with cbfα1 and CEMP1. These provided conspicuous evidence that ADAM28 may play a crucial role in root development as a potential regulator of growth, differentiation, and apoptosis of HGFs.

Effects of oral ingestion on physical functions before tube feeding in adults with severe motor and intellectual disabilities Abstract This study aimed to determine the significance of oral ingestion in tube-fed adults. Six males and three females (mean age 48.1 ± 12.4 years) with severe motor and intellectual disabilities were included in this study. The subjects were monitored for cerebral blood flow (CBF) by functional near-infrared spectroscopy imaging, gastric motor function by electrogastrography, and arterial oxygen saturation (SpO2) and pulse rate with a biological data monitoring device. The subjects were divided into two groups, settings A and B. In setting A, after resting for 30 min, the subjects were tube fed a routinely used enteral nutrient solution. In Setting B, the subjects received 10 cc of thickened enteral nutrient solution prior to tube feeding. Cerebral function as measured by CBF significantly increased after tube feeding under setting A (without oral ingestion), as compared to the resting state. Under setting B (with oral ingestion), CBF significantly increased after oral ingestion and after tube feeding. SpO2 significantly decreased under setting B after oral ingestion and after tube feeding. Gastric motor function showed no significant change after tube feeding in either setting. The pulse rate significantly increased before tube feeding as compared to that in the resting state, after feeding as compared to before feeding and after feeding as compared to the resting state. Our data suggest that introducing oral ingestion, at least partially, in tube-fed individuals with severe dysphagia is beneficial in that it can stimulate cerebral function.

Influence of environmental temperature, heat-treatment and design on the cyclic fatigue resistance of three generations of a single-file nickel–titanium rotary instrument Abstract The aim of the present study was to evaluate the effect of environmental temperature, heat-treatment*** and design on the cyclic fatigue resistance of OneShape (OS), OneShape new generation (OSNG) and One Curve (OC) NiTi rotary single-file instruments. Cyclic fatigue testing of NiTi instruments was performed in an artificial canal with a 5-mm radius of curvature and a 60° angle of curvature located 5 mm from the tip of the instrument. During the experiment 3 different temperatures were used in a thermostatic bath with electronic and infrared controls: 0°, 20° and 35 °C. Sixty OneShape, 60 OneShape new generation and 60 One Curve instruments were rotated in the artificial canal until fracture occurred and the number of cycles to fracture (NCF) and the length of the fractured fragment (FL) was recorded. Data were analyzed by one-way ANOVA test at the 5% significance level. Fatigue resistance was significantly higher as the environmental temperature decreased, with differences ranging from 61 to 791%. OC instruments were significantly more resistant to cyclic fatigue than OS and OSNG instruments at all the temperatures tested (P < 0.05). There was no significant difference with respect to the length of the fractured file fragments for all the instruments tested at all the temperatures tested (P > 0.05). Within the limitation of the present study, fatigue resistance of the files was significantly increased when the environmental temperature decreased. OC instruments were significantly more resistant to cyclic fatigue than OS and OSNG instruments at all the temperatures tested.

Cyclic fatigue resistance of three rotary file systems in a dynamic model after immersion in sodium hypochlorite Abstract To evaluate the effect of immersion in 3% sodium hypochlorite solution in the resistance to cyclic fatigue of three nickel–titanium (NiTi) rotary file systems, ProTaper Next (PTN), Hyflex CM (CM), and Hyflex EDM (EDM), in a mechanical model featuring axial movement. Ninety instruments of three different NiTi rotary file systems, PTN (size 25, 0.06 taper), CM (25, 0.06), and EDM (25/~, variable taper), were randomly divided according to a 3 × 3 factorial design and tested under dynamic immersion in a 3% NaOCl solution (1 or 5 min) or without immersion, making a total of 9 groups (n = 10). Files were tested in an artificial root canal with 45° angle and 5 mm radius apical curvature being submitted to back-and-forth movements until fracture. Statistical analysis was performed using two-way factorial ANOVA with Bonferroni post-hoc tests, at a significance level of 5%. Instruments were evaluated for reliability using a Weilbull approach. Regardless of the immersion treatment, PTN had on average 1200 ± 178 cycles to fracture, CM had 1949 ± 362, and EDM had 5573 ± 853, which was a significantly different (P < 0.01). The NaOCl immersion promoted a significant reduction in the mean number of cycles to fracture (P = 0.01), and was reflected in a significant reduction of the characteristic life of the instruments of the CM end EDM groups. Within this study conditions, EDM instruments performed better to cyclic fatigue followed by CM and then PTN. Immersion in NaOCl decreased the resistance to cyclic fatigue of all tested instruments, but affected more those manufactured from CM wire.

Comparative evaluation of the mechanical properties of CAD/CAM dental blocks Abstract This study compares the mechanical properties of commercially available CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) millable dental blocks including Vita Enamic, Lava Ultimate, and MAZIC Duro. All the discs were cut in dimension of 1.2 mm in thickness and 12 mm in diameter, ground up to #1200 Sic papers and polished. The biaxial flexure strength of the ceramic discs was measured after thermocycling treatment and the broken surfaces were observed using scanning electron microscopy (SEM). The discs were brushed using a toothbrush testing machine under a 150 g load. Surface roughness and morphology were determined after toothbrushing cycles. Finally, the friction and wear behavior of the materials against an opposing tooth were studied using a reciprocating pin-on-plate test configuration. The vertical loss of dental cusp was measured, and the surface image was examined using field emission scanning electron microscopy (FE-SEM). The biaxial flexural strength data were subjected to Weibull analysis. To compare the significance between the groups, all data were analyzed by one-way analysis (ANOVA). The biaxial flexural strength of the Lava Ultimate and MAZIC Duro materials is significantly higher than that of Vita Enamic. In addition, Lava Ultimate and MAZIC Duro exhibited significantly smoother surfaces than that of Vita Enamic after toothbrushing. Lava Ultimate and MAZIC Duro also showed less wear to the opposing tooth than that of Vita Enamic. In addition, Lava Ultimate possesses more suitable mechanical properties than the Vita Enamic and Mazic Duro for use in oral clinical prosthesis.

Changes in oral health-related quality of life after three different strategies of implant therapy: a clinical trial Abstract This research aims to evaluate changes in Oral Health-related Quality of Life (OHQoL) by means of the Oral Impacts on Daily Performances (OIDP) of patients treated with three distinct implant strategies. This clinical trial consisted of an oral examination and a questionnaire-based interview carried out before and after the definitive prosthetic rehabilitation in a consecutive sample of patients requiring dental implants. According to the clinical diagnosis and patient preference, patients were assigned to the one of the following groups: the conventional group (CGCL; n = 40), where implants were inserted without guiding and conventionally loaded; to the guided surgery but conventional loading group (GSCL; n = 35); or to the guided surgery and immediate loading group (GSIL; n = 29). At baseline, the OHQoL was significantly greater among those assigned to CGCL (2.4 ± 1.3) than those assigned to GSCL (3.3 ± 1.3), which were both greater than those patients assigned to GSIL (4.6 ± 2.0). After implant therapy, the oral well-being was significantly better than at baseline, and patient satisfaction was greater when the implants were loaded immediately (8.7 ± 1.1) than if the prosthetic rehabilitation was delayed (8.3 ± 1.1). In the GSIL group, the effect size of the OIDP exceeded the threshold value of 0.8 for all of the OIDP domains and for the total OIDP score and patient satisfaction. A global improvement in the OHQoL scores and patient satisfaction was observed after implant therapy, but the change was markedly greater in the GSIL group.

Structural and biomechanical changes to dentin extracellular matrix following chemical removal of proteoglycans Abstract Proteoglycans are biomacromolecules with significant biomineralization and structural roles in the dentin extracellular matrix. This study comprehensively assessed the mechanical properties and morphology of the dentin extracellular matrix following chemical removal of proteoglycans to elucidate the structural roles of proteoglycans in dentin. Dentin extracellular matrix was prepared from extracted teeth after complete tissue demineralization. Chemical removal of proteoglycans was carried-out using guanidine hydrochloride for up to 10 days. The removal of proteoglycans was determined by dimethylmethylene blue colorimetric assay and histological staining analyses using transmission electron microscopy and optical microscopy. The modulus of elasticity of dentin matrix was determined by a 3-point bending test method. Partial removal of proteoglycans induced significant modifications to the dentin matrix, particularly to type I collagen. Removal of proteoglycans significantly decreased the modulus of elasticity of dentin extracellular matrix (p < 0.0001). In conclusion, the subtle disruption of proteoglycans induces pronounced changes to the collagen network packing and the bulk modulus of elasticity of dentin matrix.

Activities of daily living decline is a predictor of lowered coughing ability and correlates with rehabilitative effect of tongue cleaning on coughing ability Abstract Basic activities of daily living (ADL) is a critical indicator of independency in older adults. The purpose of this study is to evaluate impact of ADL decline on coughing ability, as determined by peak expiratory flow rate (PEFR), and to evaluate impact of ADL decline on the ability of tongue cleaning intervention to improve PEFR. Methods: Participants comprised 95 residents of 11 group homes and nursing homes in Kumamoto, Japan. Participants were randomly assigned to cohorts with or without tongue cleaning intervention. Coughing ability was evaluated by measuring PEFR before and after 2 weeks, 4 weeks, and 3 months of intervention. Basic ADL was assessed by Barthel index (BI). Mean BI score among the participants was 59.3 ± 24.2. PEFR in a cohort with ≤ 60 BI score (LB) (1.2, 0.2–4.7 L s−1) was significantly lower than that in a cohort with ≥ 61 BI score (HB) (1.8, 0.5–6.5 L s− 1; p < 0.001). Multiple regression analysis revealed that BI score significantly correlated with PEFR after adjustment for various confounders (p < 0.004). Although tongue cleaning intervention increased PEFR in both cohorts, BI score only correlated with the amount of change of PEFR in the intervention group (p = 0.048). Basic ADL decline closely correlated with lowered coughing ability, as assessed by PEFR. Additionally, the rehabilitative effect of tongue cleaning on coughing ability was affected by basic ADL in older adults.

Isolation and characterization of cells derived from human epithelial rests of Malassez Abstract The epithelial rests of Malassez (ERMs) might represent a valuable source of oral epithelial cells with stem cell properties. The purpose of this study was to isolate and characterize cells derived from human ERM, and compare them with cells derived from matched normal oral mucosa (NOM). Matched tissue specimens of the periodontal ligament of extracted tooth and NOM were collected. Cells were isolated in culture, then characterized by immunohistochemistry and flow cytometry for expression of pancytokeratin, ESA, PDGFRB, CD31 and CD44. 3D organotypic cultures were constructed by growing epithelial cells on top of fibroblast-populated collagen gels. Both ERM and NOM-isolated cells expressed the markers of epithelial lineage (ESA and pancytokeratin), and to some extent PDGFR, an indicator of a more mesenchymal phenotype, but not the endothelial cell marker CD31. Cells with epithelial morphology were isolated from periodontium of cervical, middle and apical parts of the root, but contained a significantly lower percentage of ESA and pancytokeratin-positive cells than when isolating cells from NOM (p < 0.001). ERM cells expressed a significantly higher percentage of the stem cell-related molecule CD44 (cervical 92.93 ± 0.25%, middle 93.8 ± 0.26%, apical 94.36 ± 0.41%) than cells isolated from NOM (27.8 ± 1.47%, p < 0.001). When grown in 3D organotypic cultures and in collagen gels, ERM cells formed a less differentiated epithelium than NOM cells, but expressing pancytokeratin and vimentin. In conclusion, epithelial cells could be isolated from human periodontium and grown in culture; their in vitro characterization indicates that they have a less differentiated phenotype compared with cells derived from normal oral epithelium.