In vivo vs in vitro anticariogenic behavior of glass-ionomer and resin composite restorative materials.

OBJECTIVE: To evaluate the in vivo vs the in vitro anticariogenic potential of glass-ionomer and resin composite restoratives, utilizing a standardized interfacial gap model. METHODS: (a) In vitro study. Box shaped cavities were prepared at the buccal surfaces of extracted premolars limited to enamel. The incisal cavity walls received no treatment and were covered with 40 microm-thick metal spacers. The cavities were restored with a glass-ionomer (Ketac-Fil, n=8) and a fluoride-free resin composite (Scotchbond MP Plus/Z100, n=8). After 4 weeks immersion in an acidic gel (pH 4), thin sections were produced and examined under polarized-light microscopy.(b) In vivo study. Four low caries activity volunteers, with first four premolars, each planned to be extracted for orthodontic reasons, participated in the study. Cavities were prepared as before and filled contralaterally per patient with glass-ionomer (n=8) and resin composite (n=8). After 6 months in vivo, the teeth were extracted, sectioned and investigated by polarized-light microscopy, Raman microspectroscopy and SEM-EDS X-ray microanalysis. Unpaired t-test (lesion dimensions) and one-way ANOVA and Newman-Keuls tests (Ca, P wt%, Ca/P ratios) were used to identify statistically significant differences in lesion analysis (alpha=0.05). RESULTS: (a) In vitro study. All restorations developed lesions at incisal and cervical margins. At gap-free regions glass-ionomers showed reduced lesion dimensions compared to those of composites (p<0.05). At regions with gaps, no significant differences were found in lesion depth between the restorative groups tested. Lesion length was increased in composite, and decreased in glass-ionomer, whereas lesion depth in both restorative groups was increased in comparison to gap-free regions (p<0.05).(b) In vivo study. No lesions were observed at gap-free regions. At gap regions, 75.5% of glass-ionomer and 62.5% of composite restorations developed lesions. The lesion dimensions were significantly greater in glass-ionomer (p<0.05). A reduction in PO4(3-), CO3(2-), Ca and P was found in lesions compared to intact tissues. No F was detected and no CaF2 lattice vibrations were found at the enamel margins facing the gap adjacent to glass-ionomers. SIGNIFICANCE: In the presence of a standardized interfacial gap, no preventive effect was exerted in vivo from the glass-ionomer to protect the adjacent enamel wall from secondary caries attack. The lack of any correlation between the in vivo and in vitro models tested implies that artificial caries experiments have a negligible clinical relevance in predicting the in vivo effect.     

Evaluation of a new fluorescence-based device in the detection of incipient occlusal caries lesions

The aim of this in vitro study was to evaluate the performance of various contemporary detection tools at incipient occlusal caries. Thirty eight freshly extracted posterior teeth with non-cavitated occlusal caries were subjected to clinical examination and coding according to ICDAS criteria (n?=?38). Standardized fluorescence images were taken with VistaProof (Dürr Dental, Bietigheim-Bissingen, Germany). Furthermore, the teeth were calculated with a laser fluorescence pen device (DIAGNOdent pen, Kavo, Biberach, Germany). In all detection methods, assessment of caries was performed twice (with 1-week interval) by two calibrated examiners. Finally, the caries lesions were validated in tooth sections by histological examination. The intra-examiner and inter-examiner kappa coefficient, sensitivity, and specificity were determined for all detection methods at enamel lesions (D1 threshold). Degrees of agreement of each method with the histological status were calculated using receiver operating characteristic statistics and the area under curve (Az values). The kappa intra-examiner/inter-examiner coefficient values (mean?±?SD) were 0.74?±?0.04/0.73?±?0.07, 0.87?±?0.04/0.82?±?0.07, and 0.91?±?0.06/0.83?±?0.08 for clinical examination, DIAGNOdent pen, and VistaProof, respectively. The sensitivity for ICDAS was 0.80–0.86, for DIAGNOdent pen was 0.66–0.75, and for the VistaProof device was 0.97. The specificity for all the detection methods were 0.5 (0.02–0.99). The accuracy value for ICDAS was 0.76–0.81, for DIAGNOdent pen 0.66–0.71, and for the VistaProof device 0.92–0.95. The Az values (mean?±?SD) were 0.431?±?0.187, 0.583?±?0.215, and 0.486?±?0.207 for ICDAS, DIAGNOdent pen, and VistaProof examination, respectively. No significant differences in Az values were noted among the methods. All detection methods were presented with high inter-examiner and intra-examiner agreement. The new VistaProof device showed the best sensitivity, while DIAGNOdent pen demonstrated the worst one. Specificities were the same for all detection methods. Moreover, they presented the same performance in detection of incipient occlusal caries.     

Clinical evaluation of a compomer and an amalgam primary teeth class II restorations: a 2-year comparative study

PURPOSE: This study was performed to compare the clinical performance between the compomer F2000 and amalgam Dispersalloy in Class II restorations in primary molars over a 2-year period. METHODS: Seventy-five amalgam and 75 compomer restorations were placed in 75 children based on a split-mouth design. The restorations were evaluated after 1 week and after 6, 12, 18, and 24 months of oral function. The evaluation consisted of a clinical assessment according to modified Ryge criteria, a radiographic examination using bite-wing radiographs, and an observation of epoxy casts under scanning electron microscopy. RESULTS: The results showed statistically significant differences in the marginal adaptation and anatomic form between amalgam and compomer restorations. A higher number of compomer restorations were rated as Bravo, while a higher number of amalgam restorations were rated as Alpha at 24 months. Significant differences in the failure of the restoration and development of secondary caries were not found between the materials. CONCLUSIONS: The use of compomer F2000 in Class II resorations in primary molars, although it presents a significantly higher number of restorations rated as Bravo regarding the marginal adaptation and anatomic form vs the amalgam, does not increase the risks of developing secondary caries and failure of the restoration over a period of 2 years.     

Curing efficiency of various types of light-curing units

This study compared monomer conversion (DC), the per cent linear polymerization shrinkage (%LS), the wall-to-wall contraction pattern (per cent of peripheral opening, %DM, and maximal marginal gap, MG) and depth of cure (DOC), of a hybrid resin composite (Spectrum TPH) exposed to different types of light-curing units and exposure modes (Virtuoso-PAC, Elipar TriLight-QTH, and FreeLight-LED). The QTH and LED units were used in two curing modes: the exponential ramp and the continuous output modes. Monomer conversion was investigated by micro Multiple Internal Reflection (MIR)-Fourier-transform infrared (FTIR) spectroscopy and %LS was measured by the deflective disc method. The wall-to-wall contraction method used a cylindrical cavity model in extracted human teeth. The per cent debonded margins relative to the cavity periphery (%DM) and the width of maximum gap (MG) was evaluated. The DOC was determined using Vickers microhardness measurements (200 g load, 20 s) at the top surface (H0), at 2 mm (H2) and at 4 mm (H4) depths, and the results expressed as H2/H0 and H4/H0 ratios. Significantly lower %DC and %LS values were provided by PAC and LED units. No differences were found in %DM among the curing units and PAC exhibited the highest MG. No significant differences were noted among light-curing groups in terms of H2/H0 microhardness values. The QTH, operated in exponential mode, resulted in the highest H4/H0 value. The exponential mode of the QTH demonstrated superior performance for the total of the characteristics evaluated.     

Setting characteristics and cavity adaptation of low-shrinking resin composites

ObjectivesThe aim of this study was to evaluate the setting characteristics of low-shrinking resin composites and examine the possible interactions with curing efficiency and marginal adaptation in dentin cavities.MethodsThe materials tested were Ceram X Mono/CM, Premise/PR, Clearfil Majesty/CM, ELS/EL, and Filtek Silorane/FS. Polymerization shrinkage strain (%S), strain rate (%S_r) and time at maximum strain rate (t_max) were measured using the bonded disk method. Curing efficiency was measured on the top and bottom surfaces of composites with ATR-FTIR spectroscopy. Marginal adaptation was measured in unbonded (%VVF) and bonded (%XVF) specimens by computerized X-ray microtomography (micro-XCT). The % linear length of the interfacial gaps along the cavity margins (%LD) and the maximum gap width (WD_max) were calculated under optical microscopy on sectioned specimens. Statistical analysis was performed with one- and two-way ANOVA, Bonferroni's post hoc test and Pearson's correlation coefficient.ResultsThe %S values ranged from 1.34% (FS) to 2.29% (CX), while %S_r ranged from 0.06%s^?1 (FS) to 0.15%s^?1 (CX). %VVF values extended from 1.9% (FS) to 5.3% (CX) and for %XVF from 1.98% (FS) to 3.35% (CX). The values for %LD ranged from 36.52% (FS) to 81.28% (CX). Linear regression showed strong positive correlation for %S_r and t_max with %VVF (r² = 0.884 and r² = 0.927) and also for %S_r and t_max with %LD (r² = 0.823 and r² = 0.869).Significance%S_r and t_max are more representative than %S in determining the setting pattern of the materials and are strongly correlated to marginal adaptation. The silorane material showed better behavior than the dimethacrylate materials in setting shrinkage and marginal adaptation.     

3D-marginal adaptation versus setting shrinkage in light-cured microhybrid resin composites.

PURPOSE: To comparatively evaluate the 3D-marginal adaptation to dentine versus shrinkage strain of two light-cured microhybrid resin composites. METHODS: Dentine cavities (?: 2 mm; h: 1 mm; n=2x4) were prepared, filled with a single layer of EsthetX and Premise resin composites, respectively, without any adhesive cavity pre-treatment, and light-cured for 40s at 750 mW/cm2. All the specimens were imaged by computerized X-ray microtomography. Sequential sections (n=11) at 8.09 pixel size were taken at top, middle and bottom sites of each restoration relative to the axial wall and the interfacial micro-void volume fraction (%VF) was calculated. Shrinkage strain (%S) and strain rate (%SR) of the composites were measured by the bonded-disc method (n=4). The results of %VF per material and restoration site were subjected to statistical analysis by 2-way ANOVA and Tukey's test, whereas the results of %S and %SR were analysed by t-test (p=0.05). Regression analysis was performed to determine correlations between %PF and %S, %S(R). RESULTS: The results of %VF at top (t), middle (m) and bottom (b) restoration sites were (%, mean+/-S.D.): EsthetX 0.84+/-0.11 (t), 0.80+/-0.32 (m), 6.74+/-5.12 (b), Premise 0.99+/-0.24 (t), 0.92+/-0.38 (m), 1.72+/-0.97 (b). The results of %S were (%, mean+/-S.D.): EsthetX 2.60+/-0.29, Premise 1.91+/-0.10 and of %SR were (%, mean+/-S.D.): EsthetX 1.47+/-0.04, Premise 1.18+/-0.02. %VF(b) of EsthetX showed the highest values within and between the testing groups (p<0.05). %S and %S(R) values of EsthetX were significantly higher from Premise (p<0.05). Strong positive correlations were documented between %VF(b)-%S (r=0.843) and %VF(b)-%SR (r=0.943). CLINICAL SIGNIFICANCE: The results confirmed a positive correlation between setting shrinkage and interfacial gap volume at bottom sites of light-cured microhybrid composite restoration due to differential shrinkage. Shrinkage strain rate seems to be a more sensitive factor in determining percentage volume of interfacial porosity at bottom restoration sites.     

Wound healing: immunological aspects

Wound healing is a complex biological process, comprised of a series of a sequential events aiming to repair injured tissue. The role of the immune system in this process is not only to recognise and combat the newly presented antigens at the site of injury, but also to participate in the debridement of the damaged area and to contribute to the process of healing. In this review, we discuss the molecules and cells of the immune system that participate in tissue repair. We describe the mechanisms of immune recognition during initial insult and the innate and adaptive immune responses to injury. Finally, we address the role of the immune system in regeneration and repair.