Tensile strength tests of restorative resins bonded to dentin, and the resultant strengths of interfaces between the two, exhibit wide variability. Many variables can affect test results, including ...specimen preparation and storage, test rig design and experimental technique. However, the more fundamental source of variability, that associated with the brittle nature of the materials, has received little attention. This paper analyzes results from micro-tensile tests on unfilled resins and adhesive bonds between restorative resin composite and dentin in terms of reliability using the Weibull probability of failure method. Results for the tensile strengths of Scotchbond Multipurpose Adhesive (3
M) and Clearfil LB Bond (Kuraray) bonding resins showed Weibull moduli (
m) of 6.17 (95% confidence interval, 5.25–7.19) and 5.01 (95% confidence interval, 4.23–5.8). Analysis of results for micro-tensile tests on bond strengths to dentin gave moduli between 1.81 (Clearfil Liner Bond 2
V) and 4.99 (Gluma One Bond, Kulzer). Material systems with
m in this range do not have a well-defined strength. The Weibull approach also enables the size dependence of the strength to be estimated. An example where the bonding area was changed from 3.1 to 1.1
mm diameter is shown. Weibull analysis provides a method for determining the reliability of strength measurements in the analysis of data from bond strength and tensile tests on dental restorative materials.
Background
This study evaluated the synergistic effect of proanthocyanidin (PA) and casein phosphopeptide amorphous calcium fluoride phosphate (CPP‐ACFP) on remineralization of artificial root ...caries.
Methods
Demineralized root fragments (n = 90) were randomly divided into six groups based on treatments: (1) 6.5% PA; (2) CPP‐ACP; (3) CPP‐ACFP; (4) CPP‐ACFP + 6.5% PA; (5) 1000 ppm fluoride; and (6) deionized water (control). Each specimen was immersed in demineralizing solution for 14 h, testing solutions/pastes for 2 h, remineralizing solution for 8 h and pH cycling was performed at 37 °C for 8 days. Specimens were evaluated using transverse microradiography (lesion depth and mineral loss), Knoop microhardness and confocal laser scanning microscopy.
Results
Lesion depth was significantly lower in CPP‐ACFP+PA and 1000 ppm fluoride groups (p < 0.001) with no significant difference between the two groups (p > 0.05). Mineral loss was the lowest in CPP‐ACFP+PA group (p < 0.05). Fluoride and CPP‐ACFP groups showed similar mineral gain (p > 0.05). Artificial caries lesions treated with CPP‐ACFP+PA showed significantly higher microhardness values at 130 μm and 150 μm from the surface (p < 0.05).
Conclusions
Combined use of PA and CPP‐ACFP has a synergistic effect on root caries remineralization by enhancing mineral gain and increasing hardness of artificial root caries.
Background
Although various mechanical properties of tooth‐coloured materials have been described, little data have been published on the effect of ageing and G‐Coat Plus on the hardness and strength ...of the glass‐ionomer cements (GICs).
Methods
Specimens were prepared from one polyacid‐modified resin composite (PAMRC; Freedom, SDI), one resin‐modified glass‐ionomer cement; (RM‐GIC; Fuji II LC, GC), and one conventional glass‐ionomer cement; (GIC; Fuji IX, GC). GIC and RM‐GIC were tested both with and without applying G‐Coat Plus (GC). Specimens were conditioned in 37 °C distilled water for either 24 hours, four and eight weeks. Half the specimens were subjected to a shear punch test using a universal testing machine; the remaining half was subjected to Vickers Hardness test.
Results
Data analysis showed that the hardness and shear punch values were material dependent. The hardness and shear punch of the PAMRC was the highest and GIC the lowest. Applying the G‐Coat Plus was associated with a significant decrease in the hardness of the materials but increase in the shear punch strength after four and eight weeks.
Conclusions
The mechanical properties of the restorative materials were affected by applying G‐Coat Plus and distilled water immersion over time. The PAMRC was significantly stronger and harder than the RM‐GIC or GIC.
Background: The use of all‐in‐one resin‐based adhesives in clinical practice has continued to increase. The aim of this study was to evaluate retention and marginal staining of a HEMA‐free ...all‐in‐one adhesive Go! (SDI, Australia) and Ice resin composite in non‐carious cervical lesions (NCCLs).
Methods: Forty‐one restorations were placed in 13 patients (age range 44–72 years). Human Ethics Committee approval from the University of Melbourne and Dental Health Services Victoria was obtained. Restorations were bonded and placed according to the manufacturer’s instructions. Enamel etching was performed on NCCL margins after cleaning with pumice and water. Patients were recalled at six months and one, two and three years. Restorations were evaluated for retention and marginal staining, and photographic records of restorations were obtained.
Results: At three years, six patients were available for recall with 23 restoration sites reviewed. At the six‐month recall, three restorations had been lost, with a further two lost at two years. At three years, an overall cumulative retention rate of 85% was calculated using survival analysis. Fifteen of the 23 restorations showed slight marginal staining.
Conclusions: At three years, the overall retention rate of 85% indicates a satisfactory result for this new adhesive. Marginal staining was regarded as minimal.
Background: The aim of this study was to evaluate the clinical performance of G‐Bond all‐in‐one adhesive with Gradia Direct resin composite placed in non‐carious cervical lesions (NCCLs) over a ...five‐year period.
Methods: Forty‐seven restorations were placed in NCCLs in 10 subjects (age 45–75 years) after written informed consent was obtained. Institutional ethical approval for the trial was obtained before recruitment. Restorations were placed according to the manufacturer’s instructions and using 50% phosphoric acid to etch uncut enamel margins. Patients were recalled annually for five years and restorations reviewed for presence and marginal staining. Photographic records were obtained prior to restoration, immediately after placement and at each recall.
Results: At five years, 6 of the original 10 subjects were available for recall, meaning 27 restoration sites could be evaluated. All restorations remained intact apart for one partial failure at four years. This resulted in a cumulative retention rate of 97.5% of restorations at five years. Marginal staining occurred around seven restorations during the study. Staining tended to be isolated to a few patients.
Conclusions: It was concluded that G‐Bond with Gradia Direct resin composite showed excellent results over the five years of the study. This material combination seems very suitable for the restoration of NCCLs.
Background
This study compared the chemical, morphological and microhardness changes in carious dentine following application of NaOCl‐based (Carisolv), papain‐based (Papacarie) chemomechanical ...caries removal agents with conventional rotary method.
Methods
Thirty‐two carious and eight non‐carious human permanent molars were used. The carious molars were randomly distributed into four groups: Group 1 (positive control) – molars were left without caries removal; Group 2 – caries excavated with rotary method; Group 3 – caries excavated with Carisolv; Group 4 – caries excavated with Papacarie. Group 5 (negative control) consisted of eight sound molars. After caries excavation, all specimens were prepared for chemical, morphological analysis and Vickers hardness testing.
Results
EDX analysis showed no significant difference in Ca wt%, P wt% and Ca/P ratio among Groups 2 to 5. Vickers hardness of dentine from Groups 3 and 4 was significantly lower (p < 0.05) than for Groups 2 and 5. The use of Papacarie resulted in a dentine surface without smear layer and patent tubules, while Carisolv resulted in a dentine surface exhibiting two patterns: (1) the presence of smear layer or (2) patent tubules with partial smear layer formation.
Conclusions
Papain‐based (Papacarie) chemomechanical caries removal method is a reliable alternative to conventional rotary and NaOCl‐based (Carisolv) caries removal.
This study investigated cuspal deformation in teeth restored with different types of adhesive materials with and without a base.
Mesio-occluso-distal slot cavities of moderately large dimension were ...prepared on extracted maxillary premolars (n=24). Teeth were assigned to one of four groups and restored with either a sonic-activated bulk-fill resin composite (RC) (SonicFill), or a conventional nanohybrid RC (Herculite Ultra). The base materials used were a flowable nanofilled RC (Premise Flowable) and a high-viscosity resin-modified glass-ionomer cement (RMGIC) (Riva Light-Cure HV). Cuspal deflection was measured with two direct current differential transformers, each contacting a buccal and palatal cusp. Cuspal movements were recorded during and after restoration placement. Data for the buccal and palatal cusp deflections were combined to give the net cuspal deflection.
Data varied widely. All teeth experienced net inward cuspal movement. No statistically significant differences in cuspal deflection were found among the four test groups.
The use of a flowable RC or an RMGIC in closed-laminate restorations produced the same degree of cuspal movement as restorations filled with only a conventional nanohybrid or bulk-fill RC.
: Objective
To review the evidence regarding the mechanisms of silver diamine fluoride (SDF) for arresting caries.
Methods
A literature search was conducted using the keywords silver diamine ...fluoride, and its alternative names, in seven databases: PubMed, Embase and Scopus (English); China National Knowledge Infrastructure (Chinese); Bilioteca Virtual em Saude (Portuguese); Biblioteca Virtual en Salud Espana (Spanish); and Ichushi‐Web (Japanese). The titles and s were screened. Full texts were retrieved for publications that studied mechanisms of actions of SDF, including its effects on remineralisation of carious lesions and on cariogenic bacteria.
Results
A total of 1,123 publications were identified. Twenty‐nine articles were included and they investigated the effect of SDF on cariogenic bacteria and dental hard tissues. Eleven studies investigated the antibacterial properties of SDF. They found that SDF was bactericidal to cariogenic bacteria, mainly Streptococcus mutans. It inhibited the growth of cariogenic biofilms on teeth. Twenty studies reported the remineralisation of demineralised enamel or dentine by SDF. They found that mineral loss of demineralised enamel and dentine was reduced after SDF treatment. A highly mineralised surface rich in calcium and phosphate was formed on arrested carious lesions. Four studies examined the effect of SDF on dentine collagen. They found that SDF inhibited collagenases (matrix metalloproteinases and cysteine cathepsins) and protected dentine collagen from destruction.
Conclusion
SDF is a bactericidal agent and reduces the growth of cariogenic bacteria. It inhibits demineralisation and promotes the remineralisation of demineralised enamel and dentine. It also hampers degradation of the dentine collagen.
The aim of this study was to determine the bonding effectiveness of four self-etching primer adhesives after various tooth preparation protocols. Enamel/dentin specimens were prepared from 84 ...permanent molars, divided into three enamel preparation groups (silicon carbide paper SiC1; erbium, chromium:yttri-um, scandium, gallium, garnet Er,Cr:YSGG laser EL and diamond bur DB) and five dentin preparation groups (SiC, EL, DB, steelSB, and ceramic burs CBs). In each group,specimens were equally divided into four sub-groups and were bonded using Clearfil SEBond (CSE, Kuraray), Xeno IV (XE, Dentsply),Tokuyama Bond Force (TK, Tokuyama) and Filtek Silorane System Adhesive (FS, 3MESPE), as well as a hybrid resin composite(Clearfil Majesty Esthetic, Kuraray) for CSE,XE, and TK, and Filtek Posterior Restorative(3M ESPE) for FS). After 24 hours of water storage at 370C, microshear bond strength(iSBS) testing was carried out. Data were analyzed using analysis of variance (ANOVA)-Tukey test at a=0.05 and bond failure modes assessed. Representative debonded specimens were prepared and examined under the scanning electron microscope (SEM). All adhesives exhibited no significant differences in 1SBS on enamel and dentin under the clinical cavity preparation protocols, except for TK on den-tin. SEM revealed areas of altered subsurface enamel/dentin following EL ablation.
Summary
Reasons for performing study
The mechanism of hyperthermia, a potentially fatal adverse effect of erythromycin treatment of foals, is unknown.
Objectives
To determine the cause of ...erythromycin‐associated hyperthermia. It was hypothesised that the normal sweat response of foals is impaired by treatment with erythromycin.
Study design
Blinded, crossover study in 10 healthy pony foals.
Methods
Foals kept in stalls were given either erythromycin (25 mg/kg bwt orally, 3 times daily) or control for 10 days then turned out for a further 10 days. Quantitative intradermal terbutaline sweat tests were performed on Days 1 (baseline), 3, 10 and 20. The effects on terbutaline‐induced sweating of erythromycin, terbutaline concentration and treatment day were analysed by repeated‐measures ANOVA with Bonferroni‐corrected pairwise post hoc comparisons. Peak temperatures were compared by Wilcoxon's signed rank test and proportions by McNemar's related samples test. Significance was set at P<0.05.
Results
There were significant 2‐factor interactions for treatment × terbutaline after baseline, treatment × day at every terbutaline concentration, and day × terbutaline for erythromycin (P<0.001) but not control (P = 0.9) treatment. Sweating was significantly reduced from baseline in erythromycin‐treated foals at all subsequent days. Erythromycin‐treated foals produced less sweat at all time‐points than did control‐treated foals (P<0.05). Peak rectal temperatures of erythromycin‐treated foals were significantly higher (P = 0.02) than those of controls. During the first 3 days outside more erythromycin‐treated than control‐treated foals required treatment for hyperthermia (6 vs. 0; P = 0.03).
Conclusions
We believe drug‐induced anhidrosis is the likely cause of hyperthermia in some foals treated with erythromycin.
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