As people are living longer and retaining their teeth into old age, root caries is an increasingly significant problem. A minimally invasive treatment strategy, involving sealing the root caries lesion with an antibacterial resin sealant, could be highly beneficial. The aim of this study was to compare the antibacterial properties of the primers of two proprietary dentine bonding agents, Clearfil SE Bond (SE; Kuraray Medical, Japan) and Clearfil Protect Bond (PB; Kuraray Medical), which contains the antibacterial monomer methacryloyloxydodecylpyridinium bromide. Fifty-two root caries lesions were identified and randomly assigned to a primer. The lesion was cleaned, isolated, sampled with a sharp spoon excavator, a primer applied and a second sample taken. Samples were transported in fastidious anaerobe broth, vortex-dispersed and serial dilutions inoculated onto selective agars. Reduction in colony-forming units (CFU, %) after primer application was calculated for both primers for bacterial growth on each selective agar and compared to a hypothesised mean of 100% (one-sample t test, p < 0.05). No significant differences between primers were seen, indicating efficient bacterial elimination by both materials. Comparing percent reduction between SE and PB for each agar (Mann-Whitney test, p < 0.05), a significantly greater CFU reduction by PB was seen for streptococci but not other bacteria. More lesions exhibited bacterial growth and several lesions demonstrated marked bacterial growth after treatment with SE compared with PB. Therefore, PB appears to exhibit superior antimicrobial properties, particularly against streptococci. Both primers are highly antibacterial towards root caries bacteria and may therefore be suitable for minimally invasive treatment.

INTRODUCTION:The porcelain veneer is a relatively conservative means of improving the appearance of teeth. As these restorations are usually highly visible it is essential to gain the approval of the patient before final cementation takes place. As a result a variety of trial pastes are available that match the shades of the resins that are used ultimately to finally cement the veneer in place. Such restorations, by virtue of their small size and fragility, are difficult to handle and position. It is therefore important that the application of trial paste does not impede placement and retention upon the tooth surface at try in whilst the patient assesses its appearance.OBJECTIVE:To determine the rheological properties of three makes of trial pastes (Calibra - Dentsply Caulk, USA; Nexus - Kerr, USA; Rely X - 3M Espe, USA) and assess if temperature affected these. Design In vitro rheological measurement.METHOD:For each product the rheological properties of three shades were determined at both 25 degrees C and 35 degrees C three times. Measurements of both the Initial Yield Stress and Shear Rate Index were undertaken using a controlled stress rheometer (Carri-med, Dorking, UK) in flow mode with a cone-and-plate test configuration.RESULTS:One way analyses of variance of the initial yield and shear rate index for each shade of material at 25 and 35 degrees C demonstrated no significant effects of temperature with the exception of the initial yield of Nexus (P = 0.0024) where the yield stress of the white shade was significantly (P <0.01) higher at 35 degrees C than at 25 degrees C. In all cases the yield stress for Nexus was of the order of ten times higher than the other materials. All materials demonstrated pseudoplastic behaviour.CONCLUSIONS:The variation in yield stress displayed by the materials will affect the handling of veneers and offers a potentially useful choice parameter to the clinician as to which paste bests suits their requirements.

Objectives. To evaluate the equivalence of a digital X-ray system (DenOptix) to conventional X-ray film in terms of the measured radio-opacity of known filled-resin materials and the suitability of attenuation coefficient for radio-opacity determination.Methods. Discs of five thicknesses (0.5-2.5 mm) and step-wedges of each of three composite materials of nominal aluminum-equivalence of 50%, 200% and 450% were used. X-ray images of a set of discs (or step-wedge), an aluminum step-wedge, and a lead block were taken at 65 kV and 10 mA at a focus-film distance of 400 mm for 0.15 s and 1.6 s using an X-ray film or imaging plate. Radio-opacity was determined as equivalent aluminum thickness and attenuation coefficient. The logarithm of the individual optical density or gray scale value, corrected for background, was plotted against thickness, and the attenuation coefficient determined from the slope. The method of ISO 4049 was used for equivalent aluminum thickness.Results. The equivalent aluminum thickness method is not suitable for materials of low radio-opacity, while the attenuation coefficient method could be used for all without difficulty. The digital system gave attenuation coefficients of greater precision than did film, but the use of automatic gain control (AGC) distorted the outcome unusably.Conclusion. Attenuation coefficient is a more precise and generally applicable approach to the determination of radio-opacity. The digital system was equivalent to film but with less noise. The use of AGC is inappropriate for such determinations. (c) 2007 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

ObjectivesTo compare the ability of re-usable and partly disposable dental cartridge syringes to aspirate in vitro.MethodsA laboratory investigation comparing two re-usable (Astra and Rotor) and one partly disposable (Ultra Safety-plus) dental cartridge syringes. Forces needed to move the cartridge plunger and forces required to produce aspiration of Bonney's Blue dye were measured using an Instron testing machine.ResultsThere were significant differences in the forces needed to produce aspiration in the different systems (F=194, p<0.001). The Astra system needed the least force to produce aspiration. The forces required to aspirate in the Rotor and Ultra Safety-plus systems did not differ. Each system aspirated effectively in vitro at the initial aspiration manoeuvre. The forces available for subsequent aspiration attempts varied with the speed of cartridge plunger movement. The volume of local anaesthetic cartridge used did not affect the force needed to produce aspiration in the Ultra Safety-plus syringe. The method of testing free-flow of solution through the needle affected the force generated at subsequent plunger movements.ConclusionsThe re-usable and partly disposable syringes investigated aspirated effectively at the initial aspiration manoeuvre. The force available to produce aspiration at subsequent attempts varies with the speed of injection. The method of testing free-flow of solution through the needle in a loaded syringe affects the force available at the first aspiration manoeuvre.

This study evaluated the effect of salivary contamination on the shear bond strength of two highly viscous glass ionomer cements (Fuji IX GP Fast and Ketac-Molar Maxicap) to conditioned dentin and assessed the effect of cleaning the contaminated field prior to bonding. The buccal surfaces of 90 human molars and premolars were ground to expose dentin and the teeth were then set in resin. The specimens were divided into two groups for each material, then further subdivided into three groups of 15 teeth each: Group 1--uncontaminated (control), Group 2--dentin contaminated with saliva, Group 3--dentin contaminated, washed and air dried. The specimens were made by bonding the test material to dentin using a 4 mm diameter gelatin capsule. All specimens were protected with varnish and placed in distilled water at 37 degrees C for seven days prior to measuring bond strength in shear. Fractured surfaces were examined visually and by using SEM to assess mode of failure. There were no significant differences in mean shear bond strength among the three test groups for either material (ANOVA). However, shear bond strength of Fuji IX to dentin was significantly greater than Ketac-Molar (p=0.019) for all groups. Weibull analysis showed that contaminated (Group 2) specimens had a greater probability of failure at low stresses. Modes of failure were mostly cohesive for Fuji IX and adhesive/cohesive for Ketac-Molar. In conclusion, salivary contamination did not affect the mean shear bond strength of Fuji IX GP Fast and Ketac-Molar Maxicap to conditioned dentin; however, it increased the probability of failure at low stresses.

Aim To test the hypothesis that dentine and pulp protection by conditioning-and-sealing is no less effective than using a conventional calcium hydroxide lining.Methodology A cohort of healthy adults requiring a new or replacement restoration in a posterior tooth was recruited in six general practices. All procedures received local Ethics Committee approval. Exclusion criteria included signs and symptoms of pulp necrosis or inflammation, and patients unable to commit to a long-term trial. Cavity preparations were randomized to receive a calcium hydroxide lining or conditioning-and-sealing with a smear-removing bonding system. Choice of bulk restorative material (composite resin or amalgam) was at the discretion of the dentist. The key outcome measure was evidence of pulpal breakdown identified at unscheduled (emergency) or scheduled recall examinations. Postoperative sensitivity was recorded on 100 mm VAS at 24 h, 4 days and 7 days. Pulp status was assessed at 6, 12, 24 and 36 month recall, and at any emergency recall appointment. The relationship between pre-treatment and treatment variables and pulp breakdown was assessed by logistic regression (P = 0.05).Results A total of 602 teeth were recruited, with comparable numbers of cavities lined (288, 47.8%) or conditioned and sealed (314, 52.2%). The majority (492, 81.7%) were replacement restorations, and amalgam was the most common bulk restorative material (377, 62.6%). A total of 390 (64.8%) restored teeth were reviewed at 6 months, 307 (51%) at 12 months, 363 (60.3%) at 24 months, and 279 (46.3%) at 36 months post-restoration. Sixteen cases of pulp breakdown were identified within 36 months of restoration placement, 11 presenting as emergencies and five detected at routine recall examination. Logistic regression showed that preoperative pain, cavity treatment by lining or conditioning-and-sealing and the use of rubber dam isolation had no association with pulp breakdown. Pulp breakdown was associated with deep or pulpally exposed cavities (P < 0.001, odds ratio 7.8) and with composite rather than amalgam restorations (P = 0.001, odds ratio 2.13). Re-coding to identify teeth with pulp exposures revealed that pulpal exposure was the key determinant of adverse pulp outcomes (P < 0.0001, odds ratio 28.4) and that composite resin restorations were again more likely to be associated with pulp breakdown than amalgam (P = 0.017, odds ratio 3.92).Conclusions Considered within the context of routine primary dental care,Dentists can be confident that pulps will be equally well protected from post-restorative breakdown up to 36 months by calcium hydroxide lining and conditioning-and-sealing with adhesive resins.Residual dentine thickness appears to be a key determinant of pulp responses after restorative dental treatment.In deep and pulpally exposed cavities in posterior teeth, composites were associated with more pulpal breakdown than amalgams.

Objectives: The aim of this study was to evaluate the fluoride release from aged resin composites containing different types of fluoridated glass filter into both deionized distilled water and lactic acid sotution.Methods: Three resin composites, UniFil S (containing fluoro-alumino-silicate glass filter), Reactmer (containing pre-reacted glass-ionomer filter) and Beautifil (containing both types of filters) were used. A conventional glass-ionomer cement, Ketac-Fit, was used as a controt. Five disk specimens of each material were prepared and aged in water for 10 weeks. After aging, specimens were immersed in deionized distilled water for a further 6 days and then in aqueous tactic acid (pH 4.0) for 2 days. This process was repeated twice more and the specimens were subsequently immersed in water for a further 12 days. Fluoride release was measured every 2 days throughout the post-aging period.Results: The amount of fluoride release for aged UniFil S and Beautifil markedly increased in acid solution compared with water storage. The difference was not so great for aged Reactmer and Ketac-Fil. UniFit S and Beautifil gave significantly greater fluoride release in water following immersion in acid solution (p< 0.05, two-way ANOVA and Scheffe's test), but Reactmer and Ketac-Fil showed no such increase in fluoride release after acid immersion.Significance: These results suggested that the nature of the fluoridated glass filter within a resin composite and the way in which the material interacts with an acidic environment affected the amount of fluoride released. (c) 2005 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Aims: To assess the relationship between 2-body and 3-body wear for a wide variety of dental restorative materials and the suitability of using Relative Dentine Abrasivity (RDA) as a means of judging abrasivity of dentifrice pastes against these materials. Design and methods: 2-body wear tests were performed using steatite ceramic as antagonist. 3-body wear tests were performed using a variety of dentifrice pastes having a wide range of RDA values. Some 3-body tests were combined with an element of acid erosion by conditioning specimens in orange juice (pH 3.8). All tests were performed in vitro. Results and conclusions: RDA was not a reliable indicator of dentifrice abrasivity across the full range of restorative materials. Wear of resin-based materials by toothpastes can loosely be predicted from RDA but the relationship breaks down when glass ionomers are included. There is no relationship between 2- and 3-body wear. Glass ionomers perform badly under 2-body conditions but are quite resistant to 3-body wear. Glass ionomers were the only materials for which acid erosion in orange juice caused a significant increase in the rate of 3-body wear. The rate of 3-body wear was positively correlated with surface roughening.

Objectives: The aim of the study was to investigate the relationship between etch patterns produced on surface enamel by phosphoric acid and the corresponding bond strengths achieved. Materials and methods: Twenty-eight patients had the buccal surface of their teeth etched and replicated for examination under the scanning electron microscope, at the commencement of orthodontic treatment. Histometry was employed to assess the nature and quality of etch patterns using a four-point scale. Twenty of each tooth type (total of 240), were collected and A Company pre-adjusted orthodontic brackets, bonded using Transbond light-cured orthodontic adhesive according to the manufacturer's instructions and 24-hour bond strength testing was undertaken. The Adhesive Remnant Index (ARI) was recorded for the tooth and bracket surface for all specimens. Results: The type of etch was not significantly affected by the side (left or right) of the mouth assessed (p = 0.532). Overall, there was no significant difference between etch types for upper and lower teeth (p = 0.218); however, there were significant differences between specific teeth in the upper and lower arch. The greatest amount of Type A etch (well-defined etched enamel prisms) was found on the lower incisors, yet in all cases this 'ideal' etch was found to occupy less than 5% of the etched buccal surface enamel. The greatest area of etched enamel surface was occupied by Type C (etched but enamel prisms not evident). The mean bond strength values varied significantly between different tooth types, with the lowest bond strength found on the upper first molar (6.5 MPa) and the highest on the lower first molar (13.1 MPa). Conclusions: An ideal etch pattern is not essential in order to produce a strong bond.

Objective To determine the effect on the bond strength of modern dentine bonding agents to etched enamel of surface contamination with water.Design Fifteen bond strength measurements were made for bonds prepared to both moist and dry etched enamel for each of three test and one control materials.Results For two materials (Scotchbond 1 and Prime and Bond 2.1) the bond strength was not affected by the presence of water on the etched enamel surface. A mean bond strength in excess of 25 MPa was achieved for both materials under all conditions. One material (Optibond Solo) showed a 30% increase in bond strength when bonds were formed under wet condition (21.10 MPa compared with 15.35 MPa). The bond strength of the control material, a conventional unfilled bonding resin, decreased markedly with aqueous contamination (9.14 MPa compared with 26.75 MPa).Conclusion Etched enamel should be rehydrated routinely prior to bonding composite resin to its surface using a water displacing dentine bonding system.

Objective. Differential thermal analysis (DTA) using a split fiber optic light source has been reported to be a convenient method of measuring the degree of conversion (DC) of light-activated composites. The purpose of this study was to compare the results by DTA and Fourier transformation infrared spectroscopy FIR), and evaluate the usefulness of the DTA method.Methods. Experimental 2,2-bis[4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl]propane-based composites containing SiO2 filler and various amounts of triethyleneglycol dimethacrylate (TEGDMA) were prepared, and the DC of each composite was determined by DTA or FTIR with 60 s irradiation. The DC of three proprietary composites containing hybrid filler or prepolymerized resin filler were also measured by both methods with 20 or 60 s irradiation. The results were analyzed by ANOVA and Fisher's protected least significant difference test.Results. By both DTA and FTIR, the DC of experimental composites increased as the proportion of TEGDMA increased, although DTA showed 3-10%,greater values (p < 0.05) than FTIR. For proprietary composites that contain hybrid filler, the values by DTA were not significantly different from those by FTIR at 20 s exposure. Longer irradiation time resulted in greater DC (p < 0.05) for both methods, and DTA showed 5-7% greater values than FTIR. However, the DC of the composite containing prepolymerized resin filler was 30% less by FTIR than by DTA, possibly due to the influence of unpolymerized species in the filler.Significance. The DC values determined by DTA and FTIR showed good agreement for most materials including model composites. In addition, DTA may be more useful than FTIR to measure the DC of composites containing prepolymerized resin filler. (C) 2001 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.