Patients' Acceptability of Computer-Based Information on Hypodontia: A Randomized Controlled Trial.

OBJECTIVES: To compare patients' acceptability of a hypodontia-specific interactive computer-based education material (ICB-EM) versus a British Orthodontic Society (BOS) hypodontia leaflet. TRIAL DESIGN: Two-arm parallel randomized controlled trial, 1:1 allocation ratio. METHODS: The study was conducted at a specialized secondary care facility in the Greater London area. Ninety-six new hypodontia patients aged 14 y and older were randomly assigned to the control group ( n = 49) receiving the BOS leaflet or the intervention group ( n = 47) receiving the ICB-EM. The main outcome measure was patients' evaluation of the intervention measured by the treatment evaluation inventory. RESULTS: The analyzed sample comprised 76 participants: control group ( n = 38) and intervention group ( n = 38). The mean age of the sample was 19 y (SD = 7.24) and 20.3 y (SD = 6.9) for the control and intervention group, respectively. The intervention group was significantly more satisfied with the ICB-EM than individuals who received the BOS leaflet ( t = -3.53, P = 0.001). CONCLUSION: Patients preferred the computer-based information. KNOWLEDGE TRANSFER STATEMENT: Patients attending dental care in the 21st century are adept in the use of computerised facilities for obtaining information. The results of the study will provide valuable evidence for clinicians on the level of acceptability of the patients toward interactive computer based health education as opposed to traditional paper leaflets.

Water Sorption and Solubility of Luting Agents Used Under Ceramic Laminates With Different Degrees of Translucency.

PURPOSE: The aim of this study was to evaluate the effect of low-thickness ceramic laminate translucency on water sorption and solubility in resin luting agents. METHODS AND MATERIALS: Ceramic slides (15×0.7 mm) were generated using lithium disilicate (IPS e.max Press, Ivoclar-Vivadent, Schaan, Liechtenstein) that were A1 in color and had decreasing degrees of translucency (high, medium, and low). A slide of transparent glass of similar size was used as the control. Under each slide, 15 specimens (8×0.5 mm) of differing composite materials from the same manufacturer (3M ESPE Dental Products, St Paul, MN, USA) were prepared (n=5): light-cured resin cement (RelyX Veneer); dual-cured resin cement (RelyX ARC); and flowable composite (Z350XT Flow). To evaluate the loss or gain of mass, the specimens were dried until a constant mass was reached. Then, they were immersed in water for seven days and weighed immediately following removal from water. Subsequently, the specimens were dried again until a constant mass was obtained. The mass measurements were used to calculate the water sorption and solubility. Statistical analyses were carried out using a two-way analysis of variance and the Tukey test. RESULTS: Under the high-translucency ceramic slides, all of the luting agents showed similar performance regarding water sorption; the flowable composite resin and the light-cured resin cement had the lowest solubility values. Under the medium- and low-translucency surfaces, the dual-cured resin cement and the flowable composite resin showed better performance with respect to water sorption and solubility. CONCLUSIONS: In the case of high-translucency laminates, luting agents with different activation methods might be used. However, even in thin sections, decreasing the translucency of the laminate led to significant loss of light penetration, indicating a decreased likelihood of the physical activation of the resin cement.

Distal retinal ganglion cell axon transport loss and activation of p38 MAPK stress pathway following VEGF-A antagonism.

There is increasing evidence that VEGF-A antagonists may be detrimental to neuronal health following ocular administration. Here we investigated firstly the effects of VEGF-A neutralization on retinal neuronal survival in the Ins2(Akita) diabetic and JR5558 spontaneous choroidal neovascularization (CNV) mice, and then looked at potential mechanisms contributing to cell death. We detected elevated apoptosis in the ganglion cell layer in both these models following VEGF-A antagonism, indicating that even when vascular pathologies respond to treatment, neurons are still vulnerable to reduced VEGF-A levels. We observed that retinal ganglion cells (RGCs) seemed to be the cells most susceptible to VEGF-A antagonism, so we looked at anterograde transport in these cells, due to their long axons requiring optimal protein and organelle trafficking. Using cholera toxin B-subunit tracer studies, we found a distal reduction in transport in the superior colliculus following VEGF-A neutralization, which occurred prior to net RGC loss. This phenomenon of distal transport loss has been described as a feature of early pathological changes in glaucoma, Alzheimer's and Parkinson's disease models. Furthermore, we observed increased phosphorylation of p38 MAPK and downstream Hsp27 stress pathway signaling in the retinas from these experiments, potentially providing a mechanistic explanation for our findings. These experiments further highlight the possible risks of using VEGF-A antagonists to treat ocular neovascular disease, and suggest that VEGF-A may contribute to the maintenance and function of axonal transport in neurons of the retina.

The effect of tooth age on colour adjustment potential of resin composite restorations.

OBJECTIVES: The purpose of this study was to investigate the effect of tooth age on colour adjustment potential of resin composite restorations in human teeth. METHODS: Twenty extracted human premolars with an A2 shade, extracted for orthodontic reasons from younger patients (20-28yrs) (younger teeth) and periodontal reasons from older patients (45-69yrs) (older teeth), were used in this study. Cylindrical shaped cavities (3.0mm depth; 2.0mm diameter) were prepared in the centre of the crowns on the buccal surface. One of four resin composites of A2 shade (Kalore, KA; Solare, SO; Clearfil Majesty, MJ; Beautifil II, BF) was placed in the cavity, and the colour was measured at four areas (0.4mm×0.4mm) on the restored teeth (area 1; tooth area 1.0mm away from the border of resin composite restoration: area 2; tooth border area 0.3mm away from margin of resin composite restoration: area 3; resin composite border area 0.3mm away from margin of resin composite restoration: area 4; resin composite area at the centre of resin composite restoration) using a spectrophotometer (Crystaleye). The colour of each area was determined according to the CIELAB colour scale. Colour differences (ΔE*) between the areas of 1 and 2, 2 and 3, 3 and 4 and 1 and 4 were calculated, and also the ratio of ΔE*area2-3 to ΔE*area1-4 (ΔE*area2-3/1-4), ΔE*area3-4 to ΔE*area1-4 (ΔE*area3-4/1-4) and ΔE*area1-2 to ΔE*area1-4 (ΔE*area1-2/1-4) as a parameter of the colour shift in resin composite restoration, were determined. Moreover, the light transmission characteristics of the resin materials and dentine discs from the younger and older teeth were measured using a goniophotometer. The data were statistically analyzed using two-way ANOVA, and Dunnett's T3 and t-test for the post hoc test. RESULTS: ΔE*area2-3 (colour difference between resin composite and tooth at the border) and ΔE*area1-4 (colour difference between resin composite and tooth) of the older teeth groups were significantly larger than those of younger teeth groups (p<0.05). The ΔE*area2-3/1-4 (mis-match rate in colour shifting at the border) of the older teeth groups was larger than that of the younger teeth groups (p<0.05). ΔE*area3-4/1-4 (colour shifting rate of resin composite side) was significantly larger in older teeth than younger teeth (p<0.05), while ΔE*area1-2/1-4 (colour shifting rate of tooth side), was significantly smaller in older teeth than younger teeth (p<0.05). In each tooth group, there were no significant differences in ΔE*area2-3, ΔE*area1-4, ΔE*area2-3/1-4, ΔE*area3-4/1-4 and ΔE*area1-2/1-4 between the materials (p>0.05). Analysis of the light transmission properties indicated that older dentine transmitted more light, while younger dentine exhibited greater light diffusion and transmitted less light. CONCLUSIONS: The colour shifting effects at the border of the resin composite restorations were influenced by the age of the tooth. This behaviour might be influenced by the light transmission characteristics of dentine in restored teeth. CLINICAL SIGNIFICANCE: The potential for colour adjustment of resin composite restorations may be less in older teeth than younger teeth.

Stress distribution in root filled teeth restored with various post and core techniques: effect of post length and crown height.

AIM: To investigate interfacial stress distribution in restored root filled teeth with various post lengths and crown heights. METHODOLOGY: Three-dimensional mathematical models of a root filled mandibular premolar tooth were constructed. Parts of the tooth structures were replaced with ceramic crowns having three crown heights incorporating, either a cast post and core or a resin post and cores with fibre post or metallic post with four post lengths. Finite element linear analysis was performed to calculate equivalent and shear stress distribution at the interfaces between the teeth and post and cores under mesiodistal symmetrical boundary conditions and an oblique static load of 400 N. RESULTS: For the resin post and core with fibre and metallic posts, shear stress at the interface was greater in the cervical area than the post area, depending on the crown height. The resin post and core with metallic post had lower shear stress at the interface of cervical area than that of the fibre post model; however, the metallic post models produced a high concentration of shear stress at the interface between the post and resin composite. On the other hand, for the cast post and core, the shear stress at the interface was mainly produced in the post end area, which increased with decrease of post length. CONCLUSIONS: For the resin post and core, bonding integrity to the cervical area would play a critical role in the survival of the restored tooth, whereas for the cast post and core, the bond of the post would be essential.

Fabrication and characterization of polymer composites for endodontic use.

AIM: To develop a low-density polyethylene-hydroxyapatite (HA-PE) composite with properties tailored to function as a potential root canal filling material. METHODOLOGY: Hydroxyapatite and polyethylene mixed with strontium oxide as a radiopacifier were extruded from a single screw extruder fitted with an appropriate die to form fibres. The composition of the composite was optimized with clinical handling and placement in the canal being the prime consideration. The fibres were characterized using infrared spectroscopy (FTIR), and their thermal properties determined using differential scanning calorimetry (DSC). The tensile strength and elastic modulus of the composite fibres and gutta-percha were compared, dry and after 1 month storage in simulated body fluid (SBF), using a universal testing machine. The radiopacity of the fibres was determined using digital radiography. The interaction of the composites with eugenol was evaluated and compared with gutta-percha. Data of the tensile test were submitted to two-way anova and Bonferroni tests (P < 0.05). RESULTS: The endothermic peaks obtained from the DSC studies showed that the melting point of the HA/PE composites ranged between 110.5 and 111.2 °C, whereas gutta-percha exhibited a melting point at 52 °C. The tensile strength and elastic modulus of the silanated HA/PE composites were significantly higher than those of gutta-percha (P < 0.0001) under dry conditions and 1 month storage in SBF. The gutta-percha in eugenol showed a significant increase in the polymer molar mass, whereas the silanated HA/PE composites were unchanged. Radiological evaluations demonstrated that silanated HA/PE fibres were sufficiently radiopaque. CONCLUSION: Promising materials for endodontic applications have been developed, offering relevant benefits over the traditional materials in terms of mechanical and chemical properties.

Experimental etch-and-rinse adhesives doped with bioactive calcium silicate-based micro-fillers to generate therapeutic resin-dentin interfaces.

OBJECTIVES: This study aimed at evaluating the therapeutic bioactive effects on the bond strength of three experimental bonding agents containing modified Portland cement-based micro-fillers applied to acid-etched dentin and submitted to aging in simulated body fluid solution (SBS). Confocal laser (CLSM) and scanning electron microscopy (SEM) were also performed. METHODS: A type-I ordinary Portland cement was tailored using different compounds such as sodium-calcium-aluminum-magnesium silicate hydroxide (HOPC), aluminum-magnesium-carbonate hydroxide hydrates (HCPMM) and titanium oxide (HPCTO) to create three bioactive micro-fillers. A resin blend mainly constituted by Bis-GMA, PMDM and HEMA was used as control (RES-Ctr) or mixed with each micro-filler to create three experimental bonding agents: (i) Res-HOPC, (ii) Res-HCPMM and (iii) Res-HPCTO. The bonding agents were applied onto 37% H3PO4-etched dentin and light-cured for 30s. After build-ups, they were prepared for micro-tensile bond strength (µTBS) and tested after 24h or 6 months of SBS storage. SEM analysis was performed after de-bonding, while CLSM was used to evaluate the ultra-morphology/nanoleakage and the mineral deposition at the resin-dentin interface. RESULTS: High µTBS values were achieved in all groups after 24h. Only Res-HOPC and Res-HCPMM showed stable µTBS after SBS storage (6 months). All the resin-dentin interfaces created using the bonding agents containing the bioactive micro-fillers tested in this study showed an evident reduction of nanoleakage and mineral deposition after SBS storage. CONCLUSION: Resin bonding systems containing specifically tailored Portland cement micro-fillers may promote a therapeutic mineral deposition within the hybrid layer and increase the durability of the resin-dentin bond.

Effect of solvent evaporation strategies on regional bond strength of one-step self-etch adhesives to root canal dentine.

AIM: To evaluate the efficacy of different solvent evaporation strategies on bonding of one-step self-etch adhesives to root canal dentine. METHODOLOGY: Two dual-cure resin core systems (Clearfil DC Bond/Clearfil DC Core Automix and Clearfil Tri-S Bond Plus/Clearfil DC Core Plus; Kuraray Noritake Dental, Tokyo, Japan) were equally applied in 24 post spaces from extracted human mandibular premolars. After the adhesive application, specimens were randomly assigned into four water/solvent evaporation strategies as follows (I) insertion of absorbent paper point for 10 s: P, (II) 10 s air-blowing: A, (III) as (II) followed by insertion of absorbent paper point: AP, (IV) as (III) followed by 10 s additional air-blowing: APA. Then, the adhesives were light cured, and resin core materials were placed into the post space, followed by light curing for 60 s. After water storage for 24 h, 0.6 × 0.6 mm-thick beams were prepared to measure the regional µTBS. The mode of failure was also observed. The µTBS values were statistically analysed using three-way anova and Duncan HSD test (α = 0.05). RESULTS: In the coronal region, there were no significant differences in µTBS between each evaporation strategy (P > 0.05), except P group. However, in the apical region, APA and AP groups significantly increased in µTBS compared with A and P groups (P < 0.05). Only in the APA group of Clearfil Tri-S Bond Plus/Clearfil DC Core Plus, was there no significant difference in µTBS between the coronal and apical regions (P > 0.05). CONCLUSION: The use of paper points with additional air-blowing for removing excessive adhesive and evaporating residual water/solvent would be effective in producing higher bond strength for the tested one-step self-etch adhesives and fewer blister formations in deeper regions of the post space.

The relationship between bite force and oral sensation during biting in molars.

BACKGROUND: In prosthodontic treatment, the occlusal form should be designed such that bite force is applied at the position that has higher load-bearing capacity and is comfortable for the patient. The purpose of this study was to clarify the differences in bite force and occlusal sensation with different loading positions on the occlusal surface. METHODS: Twelve healthy subjects were recruited for this study. Bite force and occlusal sensation were measured at five loading points on the upper and lower left first molars. Occlusal sensation was evaluated using a Visual Analogue Scale (VAS). RESULTS: Bite forces on the lingual side of the upper first molar and the buccal side of the lower first molar were significantly higher and VAS scores were significantly lower, i.e. the subjects felt less discomfort during biting on the buccal side of the upper first molar and the lingual side of the lower first molar compared to the other side of each molar. CONCLUSIONS: Loading on the occlusal surfaces of the functional cusps of the upper and lower first molars produces more load-bearing capacity and is more comfortable than loading on the non-functional cusps.

Adhesion of indirect MOD resin composite inlays luted with self-adhesive and self-etching resin cements.

This study investigated the effect of loading on the bond strength to dentin and microleakage of MOD indirect composite restorations bonded with self-adhesive and self-etching resin cements with or without acid etching of the proximal enamel margins. Class II MOD cavities were prepared in 48 molar teeth into dentin and divided into three groups of 16 teeth. Impressions were taken and indirect composite inlays fabricated (Estenia C & B). The enamel margins of the proximal boxes of half the specimens were phosphoric acid etched, and the inlays were cemented with one of three cements (Panavia F 2.0, SA Cement, or Rely X Unicem). After luting, eight teeth in each cement group were mechanically loaded at 2.5 cycles/s for 250,000 cycles. Unloaded teeth acted as controls. Teeth were stored in Rhodamine B solution for 24 hours, sectioned buccolingually at the proximal boxes to examine microleakage using confocal microscopy, and further sectioned for µTBS testing of the resin-dentin interface. Analysis of variance was performed to assess the effect of loading and acid etching on microleakage and bond strength. Acid etching had no effect on microleakage. No significant difference in the dentin bond strengths between the three cements existed after loading. Panavia F 2.0 exhibited a significant reduction in bond strength. With regard to microleakage at the proximal boxes, loading had no effect on dye penetration at the cavity floor. However, at the axial walls, loading had a significant deleterious effect on Panavia F 2.0. No difference in microleakage existed between the three cements at both sites before and after loading. In conclusion, the two tested self-adhesive cements exhibited similar bond strengths before and after loading to the self-etching resin cement. Loading reduced dentin bond strengths and increased microleakage at the resin-dentin interface. However, acid etching of the enamel margins had no significant effect on microleakage in the approximal regions of the bonded inlays.

Adhesion to root canal dentine using one and two-step adhesives with dual-cure composite core materials.

The regional tensile bond strengths of two dual-cure composite resin core materials to root canal dentine using either a one or two-step self-etching adhesive were evaluated. Extracted premolar teeth were decoronated and their root canals prepared to a depth of 8 mm and a width of 1.4 mm. In one group, a one-step self-etching adhesive (Unifil Self-etching Bond) was applied to the walls of the post-space and light-cured for 10 s. After which, the post-spaces were filled with the a dual-cure composite resin (Unifil Core) and then half the specimens were light-cured for 60 s and the other half placed in darkness for 30 min. In the second group, a self-etching primer (ED Primer II) was applied for 30 s, followed by an adhesive resin (Clearfil Photo Bond), which was light-cured for 10 s. The post-spaces were filled with a dual-cure composite resin (DC Core) and then half the specimens were light-cured for 60 s and the other half placed in darkness for 30 min. Chemical-cure composite resin was placed on the outer surfaces of all the roots, which were then stored in water for 24 h. They were serially sliced perpendicular to the bonded interface into 8, 0.6 mm-thick slabs, and then transversely sectioned into beams, approximately 8 x 0.6 x 0.6 mm, for the microtensile bond strength test (muTBS). Data were divided into two (coronal/apical half of post-space) and analysed using three-way anova and Scheffe's test (P < 0.05). Failure modes were observed under an scanning electron microscope (SEM) and statistically analysed. Specimens for observation of the bonded interfaces were prepared in a similar manner as for bond strength testing, cut in half and embedded in epoxy resin. They were then polished to a high gloss, gold sputter coated, and after argon ion etching, observed under an SEM. For both dual-cure composite resins and curing strategies, there were no significant differences in muTBS between the coronal and apical regions (P > 0.05). In addition, both dual-cure composite resins exhibited no significant differences in muTBS irrespective of whether polymerization was chemically or photoinitiated (P > 0.05). Both dual-cure composite resins exhibited good bonding to root canal dentin, which was not dependent upon region or mode of polymerization.

Detection of acid diffusion through bovine dentine after adhesive application.

AIM: Acidic diffusion through bovine dentine was investigated by measuring pH changes on dentine surfaces after applying three adhesive systems. METHODOLOGY: Coronal incisor bovine dentine discs, 0.5 mm thick, were prepared from dentine close to the pulp chamber. A single-bottle adhesive system-Single Bond, a self-etching primer system-Clearfil SE Bond and an 'all-in-one' adhesive system-AQ Bond were used. The labial dentine surfaces were conditioned as follows: Single Bond groups: (SB-1) 35% phosphoric acid etchant was applied and left in place; (SB-2) the etchant was applied for 15 s and rinsed off for 10 s; (SB-3) application of adhesive agent and light curing following step SB-2; Clearfil SE Bond groups: (SE-1) SE primer was applied for 20 s and dried; (SE-2) application of adhesive agent and light curing following step SE-1; AQ Bond groups: (AQ-1) AQ Bond adhesive was applied for 20 s and dried, applied for additional 5 s and dried again; (AQ-2) light curing following step AQ-1. The pH change on the pulpal dentine surface was measured using a pH-imaging microscope. RESULTS: All the Single Bond groups revealed a lower pH on the pulpal surface (pH 6.25, 6.59 and 6.64 for SB-1, SB-2 and SB-3, respectively) compared with intact dentine. Clearfil SE Bond and AQ Bond groups showed no significant deference in pH value from intact dentine. CONCLUSIONS: Acid diffusion from phosphoric acid etching was observed when placed on 0.5 mm-thick dentine discs; however, there was only limited evidence of acid diffusion from SE primer and AQ Bond.

Characterisation of the dysferlin skeletal muscle promoter.

Deficiency of the skeletal muscle membrane protein dysferlin causes the related and overlapping neuromuscular disorders limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy. This paper describes the preliminary characterisation of the human dysferlin promoter. The transcriptional start site of dysferlin has been mapped using 5' RACE PCR, which extended the length of the known 5' UTR to 914 bp. Promoter elements have been mapped by assessing the ability of fragments from this region to activate the expression of a luciferase reporter gene borne on a plasmid transfected into differentiated and undifferentiated C2C12 mouse myoblast cells. Finally, the core promoter region has been screened for mutations in suspected dysferlinopathy patients.

Acidity of conventional luting cements and their diffusion through bovine dentine.

AIM: To examine the changes in pH of luting cements and acid diffusion of luting cements through bovine dentine using a pH-imaging microscope (SCHEM-100; Horiba Ltd, Kyoto, Japan). METHODOLOGY: The pH of the surface of three conventional luting cements, glass-ionomer, zinc phosphate and zinc polycarboxylate was measured with SCHEM-100 for 1 month. The acid diffusion from the three luting cements through bovine dentine was investigated by measuring pH changes during the application of each luting cement on the bovine dentine surface. Coronal bovine dentine disks were prepared to thicknesses of 0.50 and 0.25 mm. Each luting cement was placed on the labial dentine surface, and the pH change of the pulpal surface was observed every 3 min for 30 min with SCHEM-100. RESULTS: Glass-ionomer showed the lowest pH values for longer times. Neutralization proceeded furthest in zinc polycarboxylate. The 0.5-mm-thick dentine disks showed no pH change on the pulpal side with all the three cements. The 0.25-mm-thick disks revealed evidence of acid diffusion on the pulpal side of the cemented dentine and significantly lower pH when cemented with glass-ionomer and zinc phosphate than with zinc polycarboxylates. CONCLUSIONS: This study demonstrated that glass-ionomer exhibited a lower setting pH than zinc phosphate and zinc polycarboxylate, and acid diffusions from glass-ionomer and zinc phosphate cements were observed when placed on 0.25-mm-thick dentine disks.

Increased responsiveness of dopamine to atypical, but not typical antipsychotics in the medial prefrontal cortex of rats reared in isolation.

Dopaminergic hypofunction in the medial prefrontal cortex (mPFC) has been associated with the aetiology of negative symptoms and cognitive dysfunction of schizophrenia, which are both alleviated by clozapine and other atypical antipsychotics such as olanzapine. In rodents, early life exposure to stressful experiences such as social isolation produces a spectrum of symptoms emerging in adult life, which can be restored by antipsychotic drugs. The present series of experiments sought to investigate the effect of clozapine (5-10 mg/kg s.c.), olanzapine (5 mg/kg s.c.), and haloperidol (0.5 mg/kg s.c.) on dopamine (DA) and amino acids in the prelimbic/infralimbic subregion of the mPFC in group- and isolation-reared rats. Rats reared in isolation showed significant and robust deficits in prepulse inhibition of the acoustic startle. In group-reared animals, both clozapine and olanzapine produced a significant increase in DA outflow in the mPFC. Isolation-reared rats showed a significant increase in responsiveness to both atypical antipsychotics compared with group-reared animals. In contrast, the administration of haloperidol failed to modify dialysate DA levels in mPFC in either group- or isolation-reared animals. The results also show a positive relationship between the potency of the tested antipsychotics to increase the release of DA in the mPFC and their respective affinities for 5-HT1A relative to DA D2 or D3 receptors. Finally, isolation-reared rats showed enhanced neurochemical responses to the highest dose of clozapine as indexed by alanine, aspartate, GABA, glutamine, glutamate, histidine, and tyrosine. The increased DA responsiveness to the atypical antipsychotic drugs clozapine and olanzapine may explain, at least in part, clozapine- and olanzapine-induced reversal of some of the major behavioral components of the social isolation syndrome, namely hyperactivity and attention deficit.