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Biomedical subjects

Carlo Prati

Publications and source records attributed to Carlo Prati.

35 records · Page 2Linked to original sources
PubMed2004

Evaluation of bacterial adhesion of Streptococcus mutans on dental restorative materials.

Bacterial adhesion to the surface of composite resins and other dental restorative materials is an important parameter in the aetiology of secondary caries formation. The aim of the present study was to investigate the adhesion of a Streptococcus mutans strain (ATCC 25175) on the surface of different restorative materials. The test materials examined included three flowable composites (Filtek Flow, Tetric Flow, and Arabesk Flow), three microhybrid composites (Clearfil APX, Solitaire 2, and Z250), two glass-ionomers (Fuji IX, Fuji IX fast), a compomer (F2000), an ormocer (Admira), and a control reference material (tissue culture grade, surface treated polystyrene). The adhesion tests were carried out in 24-well plates. Quantitative turbidimetric measurements were finally performed in order to indirectly evaluate the amount of bacteria retained on the material surface after in vitro exposure to the bacteria suspension. Under these conditions, with the exception of the Admira ormocer and the Fuji IX fast glass ionomer, which were found to be more adhesive, all the other material surfaces showed a similar susceptibility to bacterial adhesion, exhibiting values not significantly different than the reference polystyrene control. Furthermore, the release of fluoride from some of the test surfaces did not appear capable to reduce early bacterial adhesion.

Adhesiveness↗
PubMed2004

Water movement in the hybrid layer after different dentin treatments.

UNLABELLED: The aim of this study was to examine the morphology of the hybrid layer (HL) of bonded water-stored specimens after different chemical pre-treatments of dentin. MATERIALS AND METHODS: Twenty-seven recently extracted human molars were selected. Fifty-four dentin disks in middle/deep dentin were obtained with a slow speed saw with a diamond-impregnated disk under water lubrication. Smear layers were created with 180 grit silicon carbide under running water for 1 min. Different pre-treatments of dentin were: Group (1) no treatment; Group (2) 35% H3PO4 etch for 15 s followed by 10% glutaraldehyde for 120 s; Group (3) 37% H3PO4 etch for 15 s followed by 5% NaOCl for 120 s. Three dentin bonding agents (DBAs), Prime and Bond NT (P and B), AdmiraBond (AB), and Clearfil SE Bond (SEB) were applied in association with a resin composite following the manufacturers' directions. Each specimen was then longitudinally sectioned and polished with wet SiC papers (up to #4000 grit). Impressions of the polished dentin were immediately taken with a silicone impression material. Bonded specimens were then stored for 3 or 12 h in deionized water. Further impressions of stored specimens were taken after air-drying of specimens for 10 s. Positive replicas were obtained using a polyether impression material. All the replicas and the original specimens were inspected by SEM. RESULTS: A line of droplets (0.5-4 microm in diameter) was observed along the region of the adhesive-HL junction in all replicas of specimens stored in water, except in group 3, when P and B and AB were used. When SEB was used in each group the droplet were found in all groups except the zone of droplets was thinner. No differences in droplets dimensions were seen between 3 or 12 h water storage, or between the different dentin treatments. CONCLUSIONS: The replica procedure used in this study was able to detect water trapped in the adhesive-HL region that was released during the setting of the impression material. The droplets observed in this region support the hypothesis that there can be bidirectional water movement within the adhesive-HL complex.

Acid Etching, Dental↗
PubMed2004

Electron microscopic detection of salivary alpha-amylase in the pellicle formed in situ.

Immunological and biochemical analyses have shown that alpha-amylase is an essential component of the acquired pellicle. After adsorption, this enzyme might act as a receptor for bacterial adherence. However, data indicating that amylase is bound to the pellicle surface in vivo and thus available for adhering bacteria are rare. Therefore, the present study focused on alpha-amylase within the pellicle formed in situ, using gold-immunolabeling electron microscopic techniques. Pellicles were formed by intra-oral exposure of enamel specimens for 30 and 120 min in six subjects. The results obtained by transmission electron microscopy indicate that amylase was randomly distributed in the pellicle layer without any preferential localization within the pellicle. Thus, salivary alpha-amylase might be considered as an important structural component that is even involved in the early stages of pellicle formation. The findings of field emission in-lens scanning electron microscopy provided evidence that the enzyme is located on the pellicle surface. It could be concluded that alpha-amylase might act as a receptor for bacterial adherence to the pellicle in vivo.

Adsorption↗
PubMed2004

Heart rate variability: a sensitive parameter for detecting abnormal cardiocirculatory changes during a stressful dental procedure.

BACKGROUND: The authors conducted a study to evaluate the sensitivity of heart rate variability, or HRV, in quantifying the cardiocirculatory reaction to dental stress compared with other clinical parameters more frequently used in clinical practice. METHODS: Twenty-five healthy subjects (15 men and 10 women aged 19 through 73 years) who underwent dental extractions were enrolled in the study. The authors measured systolic blood pressure, or SBP; diastolic blood pressure, or DBP; heart rate, or HR; and HRV at baseline, immediately after local anesthetic was administered, during the dental extraction and five minutes after the dental extraction. Time domain measures of HRV were based on interbeat intervals and were obtained by using standard deviations of the R-R intervals, which were calculated during a five-minute period in a continuous electrocardiographic record. RESULTS: Analysis of variance for repeated measures showed no time-related difference between the four study periods with regard to SBP and DBP. However, HR values were significantly different in three of the four periods, and HRV values were significantly different in all four testing periods. Furthermore, HRV values exhibited greater variability in the maximum changes recorded during dental extractions compared with HR values (0 to 80 milliseconds versus 0 to 31 beats/minute, respectively). CONCLUSIONS: HRV is a highly sensitive parameter for quantifying the sympathetic drive to the heart during a cardiovascular reaction to a dental operation. CLINICAL IMPLICATIONS: Clinicians may find that HRV evaluation is useful in monitoring patients with heart disease to detect early signs of cardiac impairment related to local, high sympathetic activity and to prevent cardiovascular emergencies.

Adult↗
PubMed2004

Morphological evaluation of enamel surface after application of two 'home' whitening products.

PURPOSE: The purpose of this study was to investigate the effect on enamel surface morphology of two commercially available bleaching products (AZ Whitestrips 6% hydrogen peroxide - Procter & Gamble; Platinum TWS 10% carbamide - Colgate Oral Pharmaceuticals) and their ability to prevent enamel demineralization in the presence of cariogenic solution, with or without saliva. MATERIALS AND METHODS: Forty sound teeth were used to obtain 90 enamel fragments. Lactic acid (pH = 4.4) was used as a demineralizing cariogenic solution. The specimens were randomized into eight groups: Group A: product A + cariogenic solution; Group B: product B + cariogenic solution; Group C: cariogenic solution; Group D: (control group) stored in deionized water; Group E: product A + deionized water; Group F: product B + deionized water; Group G: product A + saliva; Group H: product B + saliva. Scanning electron microscope (SEM) analysis was performed to detect the type of lesions induced by the treatments. A score rating system was used to perform a non-parametric statistical analysis. RESULTS: Our study confirms that enamel alterations (i.e. removal of intraprismatic core and presence of deep porosities and pits) occur as a result of the application of a cariogenic solution (lactic acid). The enamel surface presented a honeycomb surface only in untreated samples previously stored in lactic acid solution. Conversely, both products were able to prevent enamel alterations caused by exposure to lactic acid. Saliva treatment reduced the degree of enamel lesions of both treated and untreated groups. Treatment with product A achieved better preservation of enamel integrity. CONCLUSION: Whitening treatment conducted with two 'home' bleaching agents had no adverse effects on enamel surface morphology. Several morphological aspects suggest that the tested products may even prevent demineralization of the enamel surface after exposure to lactic acid.

Carbamide Peroxide↗
PubMed2003

Effect of dentinal pretreatments on coronal dentin primary carious lesions: a field emission SEM study.

The aim of the study was the morphological analysis of coronal dentin caries and the modifications induced by different pretreatments with phosphoric acid or sodium hypochlorite. Carious dentin specimens were obtained from human molars affected by carious lesions. Specimens were divided in four groups and submitted to: (1) untreated; (2) 35% phosphoric acid for 15 s; (3) 35% phosphoric acid for 15 s and 5% sodium hypochlorite for 2 min; (4) sodium hypochlorite for 5 min. Specimens were observed under high-resolution SEM. Different areas were identified within the carious lesion: a deeper, inner region revealing closed highly mineralized tubules, and a more superficial outer layer showing an increasing demineralization rate toward the surface of the lesion. Phosphoric acid followed by NaOCl treatment removed all collagen fibrils from greatly altered carious outer-dentin layer. The 5-min treatment with sodium hypochlorite affected both inner and outer dentin, removing all collagen fibrils and increasing the porosities of deeper intertubular hypermineralized dentin. FEISEM analysis confirmed that only inner carious dentin after phosphoric acid treatment may be considered a suitable substrate for dentinal bonding system. On the contrary, the outer dentin is an unstable substrate for any type of bonding systems and must be avoided/removed from any surface before conditioner application.

Acid Etching, Dental↗
PubMed2003

Sorption and solubility of resin-based restorative dental materials.

OBJECTIVES: To measure the water sorption and solubility of different resin-based restorative dental materials. METHODS: Eight commercial restorative materials were selected: two resin composites (Z100 and Prodigy), four polyacid-modified resin composites (Compoglass, Compoglass F, Dyract and Dyract AP), and two light-cured glass ionomers (Vitremer and Fuji II LC). Five disc specimens were prepared of each material, following the manufacturer's instructions, and were grounded wet with silicon carbide paper. Water sorption and solubility of the different materials were calculated by means of weighting the samples before and after water immersion and desiccation. Data were analyzed by one-way ANOVA and Student-Newman-Keuls tests (P<0.05). RESULTS: Compoglass and Compoglass F showed the lowest values of water sorption and solubility, while Vitremer and Fuji II LC displayed the highest values. Solubility values of Prodigy, Z100, Dyract and Dyract AP did not show significant differences among them, while their water sorption values attained some differences and were lower for Prodigy followed by Dyract and Z100. CONCLUSIONS: The attained water sorption and solubility values are mainly influenced by the generic type of material and variations occurring between materials of the same type may result from differences in resin matrix compositions.

Absorption↗
PubMed2003

Permeability and morphology of dentin after erosion induced by acidic drinks.

BACKGROUND: The aims of this study were to evaluate 1) the alterations of dentin permeability after single exposure of dentin to several acidic soft drinks with different acid composition; 2) the effectiveness of smear layer on dentin surface to prevent erosion of sound dentin; and 3) the role of brushing procedures. METHODS: Dentin discs from human third molars were prepared. Each disc was treated with 0.5 M neutral EDTA for 5 minutes to remove the smear layer and to calculate the maximum fluid flow rate for each disc (to which an arbitrary value of 100% was assigned) using a pressure apparatus working at 1.0 psi. An homogeneous thin smear layer was then recreated with an abrasive paper under water. The following acidic drinks were applied for 5 minutes onto dentin surface: cola drink (phosphoric acid), orange fruit juice (ascorbic + citric acid), white wine (tartaric acid), vinegar (acetic acid), and mucolytic syrup (benzoic and tartaric acid). Each sample was then brushed for 3 minutes. Finally, each sample was brushed with a toothpaste and, as the final step, etched with phosphoric acid for 1 minute. Permeability was measured after each step. RESULTS: All acidic drinks were able to statistically increase dentin permeability and to open dentinal tubules by removing the smear layer. CONCLUSIONS: The study demonstrated that acidic drinks increased dentin permeability by removing and dissolving the smear layer and smear plugs. The erosion of peritubular dentin and smear plug removal is the main agent responsible for the increase in dentin permeability and probably for clinical dentin hypersensitivity. Brushing procedures reduced dentin permeability, creating a new fine and thin smear layer. Toothpaste may play a protective role in preventing complete smear layer removal and reducing dentin hypersensitivity by producing a new artificial smear layer and deposit inside tubules. The use and the abuse of acidic drinks may damage dentin and increase the risk for dentin hypersensitivity.

Acids↗
PubMed2003

Ultra-morphology of self-etching adhesives on ground enamel: a high resolution SEM study.

PURPOSE: To evaluate the effect of different commercial self-etching agents on enamel morphology using high-resolution in-lens scanning electron microscopy (FEISEM). METHODS: The bonding systems selected for the study were: Prime & Bond NT (no-etch technique), Prime & Bond 2.1 (no-etch technique), NRC/Prime and Bond NT, Syntac Single Component, Prompt L-Pop, F2000, and Clearfil SE Bond. The positive control group was prepared with Single Bond upon etching enamel with the proprietary 35% phosphoric acid gel. 24 extracted human molars were equally and randomly assigned to the experimental and control groups. All bonding materials were applied on enamel following the manufacturers' instructions. A thin layer of composite was applied on the polymerized adhesive agent, after which the enamel was dissolved to obtain replicas that were observed under a FEISEM. RESULTS: Observations revealed different morphological features brought about by the adhesive systems. A relationship between the morphological appearance and the pH of the adhesive solutions was found. Three different groups of self etching were identified: Group 1 showed no or little evidence of modifications on the enamel surface (Prime & Bond NT and Prime & Bond 2.1, no-etch technique), Group 2 revealed major aggressive properties that were able to disclose the prism morphology (Syntac Single Component, F2000, Clearfil SE Bond), and Group 3 (NRC/Prime & Bond NT and Prompt L-Pop) revealed morphological features similar to those obtained with Single Bond after etching with phosphoric acid (control group).

Acetone↗
PubMed2003

Effects of different acid and sodium hypochlorite treatments on dentin collagen: a FEISEM analysis.

PURPOSE: To evaluate if different acid treatments of dentin surface might remove different amount of mineralized dentin, thus exposing and modifying the CF network. METHODS: Dentin disks prepared from human third molars with a low-speed diamond saw were etched for 15 seconds with the tested acids: citric acid 10%, maleic acid 10%, 2.5% oxalic acid, 35% phosphoric acid and 24% EDTA gel. Specimens were then submitted to a 5% solution of NaOCl for 2 minutes or 5 minutes, fixed, and observed utilizing a field emission in lens SEM (FEISEM). Control specimens were also prepared by omitting the etching agent and/or the NaOCl solution. RESULTS: The different acid treatments created specific dentin morphological pattern. CF exposure was in relationship with the acid used. The NaOCl solution greatly affects the acid etched dentin by removing the CF, nevertheless the effect of NaOCl was greatly influenced by the previous acid treatment.

Acid Etching, Dental↗
PubMed2003

Factors contributing to the incompatibility between simplified-step adhesives and self-cured or dual-cured composites. Part II. Single-bottle, total-etch adhesive.

PURPOSE: As adhesives containing hydrophilic/acidic resin components are vulnerable to water movement after polymerization, this study tested the hypothesis that coupling of a single-bottle adhesive (OptiBond Solo Plus) to self/dual-cured composites is compromised by adhesive permeability, even with the adjunctive use of chemical co-initiators. MATERIALS AND METHODS: Two versions of chemical co-initiators (activators) were investigated: the proprietary resin-containing OptiBond Solo Plus Activator (A), and a resin-free solution of 2% benzene sulphinic acid sodium salt in ethanol (B). For microtensile bond testing, hydrated (H) or dehydrated (D) bonded human dentin were coupled to a dual-cured composite (Bis-Core) under light- (L) or self-activation (C) mode. A delayed light-activation mode (DL) was also employed to simulate the slower rate of polymerization of self-cured composites but without the influence from adverse chemical interaction. Nine groups were tested: 1) L-H (control); 2) DL-H; 3) DL-D; 4) C-H; 5) C-D; 6) CA-H; 7) CA-D; 8) CB-H; and 9) CB-D. For transmission electron microscopy, a light-cured and an experimental self-cured composite of the same composition were used for the nine groups. RESULTS: Only the bond strength results of the experimental groups DL-D (Group 3) and CB-D (Group 9) were not significantly different from the control group L-H (p > 0.05). TEM revealed the presence of discrete silver-filled water blisters along the adhesive-composite interface in groups 2, 6, and 8, and within the composite in group 4. Adverse chemical interaction in groups 4 and 5 resulted in the observation of a line of silver deposits along the adhesive composite interface. CONCLUSION: The coupling of composites after prolonged contact with hydrated dentin bonded with OptiBond Solo Plus is affected by the intrinsic permeability of the adhesive. The adjunctive use of the Activator is only slightly effective in improving the coupling of this adhesive with self/dual-cured composites. Although the use of resin-free benzene sulphinic acid sodium salt solution completely eliminates the adverse chemical interaction, the inherent permeability of the polymerized adhesive precludes optimal coupling of self/dual-cured composites to bonded hydrated dentin.

Acid Etching, Dental↗
PubMed2002

Effectiveness of metronidazole gel on cyclosporine-induced gingival overgrowth in heart transplant patients.

To evaluate the efficacy of metronidazole on cyclosporine-induced gingival overgrowth (GO), a prospective intra-subject double-blind longitudinal study was performed on six heart transplant patients with GO. All patients underwent scaling and root planing before any treatment. Metronidazole gel (Elyzol, Cabon) was then applied in two of the four anterior hemi-sextants of each subject, following a balanced random pre-programmed list, with a placebo gel being applied to the remaining two hemi-sextants. Plaque index (PI), bleeding on probing (BP) and probing depth (PD) were recorded for all teeth of the four anterior hemi-sextants before and at 1, 2, 3, and 4 months after gel application. A general linear model was fitted and ANOVA for repeated measurements with split-plot design and Chi-square analysis were used for statistical analysis. PD significantly decreased after 1 month following both treatments. Analogous results were obtained as regards PI and BP. No statistically significant difference was detected between results obtained with metronidazole and placebo. However, PD in the group of teeth treated with placebo significantly increased after 4 months, while PD values obtained from teeth treated with metronidazole remained statistically unchanged with respect to the 1st month. In conclusion, short-term results suggest that metronidazole and placebo are equally effective in reducing periodontal parameters and GO when associated with scaling and root planing. Long-term results, however, showed greater efficacy of metronidazole with respect to placebo in controlling cyclosporine-induced GO.

Analysis of Variance↗
PubMed2002

Circulatory dynamics during dental extractions in normal, cardiac and transplant patients.

BACKGROUND: The authors conducted a study to evaluate the relationship between the circulatory dynamics of patients with heart disease and these patients' cardiac status when undergoing dental extractions. METHODS: Subjects with minimal heart disease, or MHD; with severe heart disease, or SHD; or who received a heart transplant, or TRAN; as well as control, or NOR, subjects were enrolled in the study. The authors recorded subjects' systolic blood pressure, or SBP; diastolic blood pressure, or DBP; and heart rate, or HR, while they were under basal conditions and during postanesthesia and dental extraction periods. The authors estimated a general linear model and performed analysis of variance. RESULTS: Under basal conditions, MHD subjects did not show significantly different mean blood pressure values compared with NOR subjects but did show slightly significantly higher mean HR values. Mean DBP and HR values were significantly higher in SHD and TRAN subjects than in MHD and NOR subjects, while SBP values in SHD subjects were significantly lower than those in MHD, TRAN and NOR subjects. During dental extraction sessions, SBP, DBP and HR mean values increased significantly compared with basal conditions and post-anesthesia periods in MHD and NOR subjects. SHD and TRAN subjects showed no significant time-dependent variation during dental extraction sessions in any circulatory parameter. CONCLUSIONS: MHD subjects had cardiovascular responses to stress similar to those of NOR subjects, while SHD and TRAN subjects had similar slight and dulled cardiac responses. CLINICAL IMPLICATIONS: Patients with SHD may not be able to adapt their cardiac performance to an emotional stress such as a dental appointment, while it seems to be easier for MHD and TRAN patients. Managing TRAN patients is relatively easier than managing SHD patients.

Adult↗
PubMed2002

Dentin morphology and permeability after brushing with different toothpastes in the presence and absence of smear layer.

BACKGROUND: The purpose of this study was to evaluate the morphology and permeability of dentin after brushing with different toothpastes in the presence and absence of smear layers. METHODS: Dentin discs were prepared from extracted third molars. Dentin permeability was measured using a hydraulic pressure apparatus working at 70 cm H2O pressure. Dentin was treated with 0.5 M EDTA for 5 minutes and washed to remove a smear layer and to establish the maximum permeability of each dentin disc, which was expressed as 100%. A new smear layer was then created on the upper surface using a #400 carbide paper under water for 30 seconds. Dentin permeability of the smear layer-covered dentin was measured and expressed as a percentage of the maximum permeability of that specimen, permitting each specimen to serve as its own control. Each sample was then brushed by a mechanical device under water for 3 minutes with constant pressure of 250 g using a medium toothbrush and permeability remeasured. Finally, 1 of 5 different toothpastes was applied on the dentin and brushed for 3 minutes. In another group, the same procedures were performed with the exception of the smear layer production, so it was possible to calculate changes in the permeability of dentin with open tubules following brushing. Scanning electron microscopic (SEM) examination of dentin was obtained before and after treatments with brushing and toothpastes. RESULTS: Dentin permeability was reduced by brushing procedures when the smear layer was absent, but it was increased when the smear layer was present. Toothpaste application reduced dentin permeability when no smear layer was present on the top of the surface, but modified and increased permeability of samples with smear layers. SEM observations demonstrated the presence of dentifrice particles on dentin surfaces and inside dentinal tubules, and this may be responsible for the observed reductions in permeability. Smear plugs produced during dentin brushing were not removed by the dentifrices. CONCLUSIONS: Dentin permeability and morphology are significantly affected by toothbrushing and by the type of dentifrice used. The presence of smear plugs in the dentin may decrease severity.

Adult↗
PubMedDate not supplied

Microleakage and marginal hybrid layer formation of compomer restorations.

The tested hypotheses of this study were that dentin enamel bonding agents (DBAs) proposed for compomers create a hybrid layer (HL) that seals the margins of Class V restorations and HL is free from voids or gaps on both enamel and dentin margins. For purposes of this study, Class V restorations (n = 70) were made in vitro at the CEJ in extracted third molars. Different systems (bonding agent + compomer) were selected. After finishing with discs, each margin was polished with diamond polishing paste for one minute, treated with a 2.5% NaOCl gel for 10 seconds and washed with deionized water to remove polishing debris and non-infiltrated collagen. All restorations were immersed in dye solution for 24 hours, then inspected along the margins. SEM analysis was used to evaluate the morphology of the marginal HL and microleakage tests to evaluate their ability to seal the margins of restorations. Marginal leakage was observed along the dentin and enamel margin. A thin marginal HL (0.5-1.2 microm) was detected only along the dentin margin of several bonding systems but not along the enamel margin. Porosities and gaps were detected along margins when no HL was observed. The results demonstrated that the tested bonding agents for compomers produced a thin marginal hybrid layer, especially along the dentin margin. Microleakage had a relationship with the morphology (gap, porosities and thickness) of this hybrid smear layer. In conclusion, the DBAs tested specifically developed for compomers did not ensure an intimate interfacial adaptation, because microleakage was detected along the enamel and dentin interfaces and the marginal hybrid layer was only partially homogeneous.

Adult↗
PubMedDate not supplied

Immunohistochemical analysis of collagen fibrils within the hybrid layer: a FEISEM study.

This study evaluated the immunohistochemical labeling pattern of dentin collagen fibrils within hybrid layers created by different bonding systems using high resolution SEM. Four different adhesive materials, including self-etching and total-etching systems, were examined: Prime & Bond NT, OptiBond SOLO Plus, Single Bond and Clearfil Protect Bond. All materials were applied to the dentin of extracted human third molars. After cutting the bonded specimens transversely, an anti-collagen type I antibody was incubated on the surface of the dentin-adhesive interface and gold-conjugated secondary antibody was applied to reveal collagen labeling under high resolution SEM. The hybrid layers showed a significant number of collagen fibrils embedded in the resin matrix. The presence of exposed dentin collagen fibrils, as determined by positive labeling with an anti-type I collagen monoclonal antibody, is considered an indication of the presence of incompletely embedded fibrils and, thus, the quality of dentin matrix hybridization. The hybrid layers produced by total-etching systems showed higher labeling compared to those produced by the self-etching system. Positive collagen labeling was also found along the resin tags produced by total-etching adhesive systems.

Acid Etching, Dental↗