RCAAP Repository

This study evaluated the shear bond strength of porcelain/composite using 40 metal + porcelain + composite cylindrical specimens divided into 4 groups, according to porcelain surface treatment: 1) no treatment, 2) mechanical retentions performed with diamond burs, 3) etching with phosphoric acid+silane, and 4) etching with hydrofluoric acid+silane. After being stored in distilled water at room temperature for one week, the specimens were submitted to a shear force (load) and the data were analyzed statistically (ANOVA). The means (in Mpa) of the groups were: 4.71 (group 1); 4.81 (group 2); 11.76 (group 3); 11.07 (group 4). There were no statistically significant differences between groups 1 and 2 and between groups 3 and 4.

The aim of the present study was to evaluate the image quality of four direct digital radiographic systems. Radiographs were made of the maxillary central incisor and mandibular left molar regions of a dry skull, and an aluminum step-wedge. The X-ray generator operated at 10 mA, 60 and 70 kVp, and images were acquired with 3, 5, 8, 12, 24 and 48 exposure pulses. Six well-trained observers classified the images by means of scores from 1 to 3. Collected data were submitted to nonparametric statistical analysis using Fisher's exact test. Statistical analysis showed significant differences (p<0.01) in image quality with the four systems. Based on the results, it was possible to conclude that: 1) all of the digital systems presented good performance in producing acceptable images for diagnosis, if the exposures of the step-wedge and the maxillary central incisor region were made at 5 pulses, as well as at 8 pulses for the mandibular left molar region, selecting 60 or 70kVp; 2) higher percentages of acceptable images were obtained with the administration of lower radiation doses in CCD-sensors (charge-coupled device); 3) the Storage Phosphor systems produced acceptable images at a large range of exposure settings, that included low, intermediate and high radiation doses.

Since dental plaque reservoirs of fluoride (F), calcium (Ca) and inorganic phosphorus (Pi) are susceptible to decreases in pH, this in situ crossover study was conducted to test the hypothesis that the low concentration of these ions in plaque, formed in the presence of sucrose, could be attributed merely to the fermentation of this sugar. Eleven volunteers wore palatal appliances containing 6 human enamel blocks during two stages. In each stage, the treatments were either 20% sucrose solution or distilled deionized water, which were dripped onto the blocks 8 times a day. After 28 days, in each stage, the dental plaque formed on two blocks was collected, the treatment was inverted and after a further 24 and 48 h, the biofilm formed was collected from the other blocks. The concentration of acid-soluble F, Ca and Pi, and the concentration of insoluble polysaccharide (IP) were determined in the dental plaque. Statistically lower concentrations of F, Ca and Pi, and a higher concentration of IP were found in the 28-day biofilm formed in the presence of sucrose than in its absence; after the treatment inversion the change in F, Ca and Pi was not statistically significant, but the IP concentration changed significantly. The hypothesis was rejected because change in concentration of F, Ca and Pi is not due to fermentation of the sucrose.

The aim of this study was to measure the caries prevalence in the root surface in a group of Brazilian adults. The prevalence and their intraoral distribution of caries lesions of root surface were assessed in dental patients ranging in age from 35 to 44 and from 50 to 59 years of age of both sexes (n=360). A total of 98.9% had root surfaces with gingival recession and 78.1% had at least one root caries lesion. The prevalence of the disease was analyzed using the Root Caries Index (RCI). The average value was greater for women (18.6%) than for men (13.4%) (p<0.01) and similar in both age groups (p>0.01). The maxillary canines and first premolars and the mandibular molars presented the greatest RCI values. The RCI was greater in the proximal surface of the maxilla and buccal surface of the mandible. We conclude that caries of the root surface are present in the Brazilian population and deserve attention concerning their actual role in the epidemiology of principal oral diseases of the adult population.

This study evaluated the correlation between the presence of black extrinsic tooth stains and caries in Brazilian schoolchildren. The target population consisted of 263 children aged 6-12 years. Clinical examinations were performed by four dentists calibrated for the World Health Organization criteria for caries diagnosis. The c² test was used to compare the prevalence of caries between groups of children with and without black tooth stains. Spearman's correlation test was used to analyze the relationship between the presence of black stains and caries severity. Black stains were observed in 14.8% of the children. The number of children with caries-free permanent dentition was not statistically different between groups. The mean DMF-T was 1.46 ± 1.39 for children with black stains and 2.42 ± 2.09 for children without black stains. A negative correlation was observed between the presence (r = -0.16; p<0.05) and severity (r = -0.15; p<0.01) of black stains and DMF-T.

Enamel hypoplasia is the most common developmental defect of human teeth that may be seen in deciduous teeth of babies born to diabetic women. In the present experimental study, we analyzed the enamel organ of the mandibular incisors of the offspring of rats with alloxan-induced diabetes. By light microscopy, no alterations could be found in the enamel organ of rats born to diabetic mothers compared to normal ones, except in one case. In contrast, significant differences were detected with computer-aided morphometry. In the rats born to treated and untreated diabetic mothers, there was thinning of the enamel matrix and of the ameloblasts and the nuclear area of the latter was smaller. In the rats born to treated diabetic mothers, the nuclei of the ameloblasts were more elliptical and there was enlargement of the interstitial area of the stellate reticulum. These results indicate that there are structural defects in the enamel organ of rats born to mothers with alloxan-induced diabetes which could induce the enamel hypoplasia observed by scanning electron microscopy and which may reflect the metabolic alterations seen in this condition. Future studies are needed to determine whether these effects are transitory or permanent.

The aim of this in vitro study was to evaluate by scanning electron microscopy the morphological aspects of the enamel of primary teeth after etching with 36% phosphoric acid or a non-rinse conditioner. Ten naturally exfoliated anterior primary teeth were selected. The samples were subjected to prophylaxis with pumice paste and water using a low-speed hand piece. Etching was done on the buccal surface. Specimens were divided into 2 groups: G1 (n=10): etching with 36% phosphoric acid gel - Conditioner 36 (Dentsply) for 20 s, followed by water rinse for 15 s; G2 (n=10): etching with NRC - Non Rinse Conditioner (Dentsply) for 20 s, followed by air drying for 15 s. The samples were dehydrated, mounted on metal stubs, coated with gold and observed with Jeol JSM-6100 scanning electron microscope. Electron-micrographic analysis showed that both etching agents were effective for etching the enamel of primary teeth causing the formation of microporosities on the enamel surface, although the etching pattern was more effective with the use of 36% phosphoric acid gel.

The purpose of this study was to analyze the morphological alterations that occurred in the parotid glands of rats maintained on a liquid diet compared to a solid diet. Thirty-six animals were randomly divided into two groups. The control group received a solid diet, and the experimental group received a liquid diet. The animals were killed after 8, 15 and 30 days. The glands were prepared for inclusion in paraffin and analyzed with a light microscope. The results showed a statistically significant reduction of the parotid gland weight of the animals from the experimental group compared to the control group at 15 and 30 days. The strongest morphological alteration displayed was the presence of cytoplasm vacuoles on the parotid glands of the animals maintained on the liquid diet. Specific stain techniques for glycoproteins and mucopolysaccarides could not identify the substances inside the vacuoles observed in the experimental animals. We conclude that a liquid diet caused atrophy of the parotid gland after 15 and 30 days.

The aim of this study was to assess histologically the effect of LLLT (l 830 nm) on the repair of standardized bone defects on the femur of Wistar albinus rats which were grafted with inorganic bovine bone Gen-ox®. Three randomized groups were studied: group I (control, n=6); group II (Gen-ox®, n=9) and group III (Gen-ox® + LLLT, n=9). The animals were irradiated every 48 h during 15 days; the first irradiation was performed immediately after the procedure. The animals were irradiated transcutaneuosly at four points around the defect. At each point a dose of 4 J/cm² was given (Ø~0.6 mm, 40 mW) and the total dose per session was 16 J/cm². The animals were killed by an overdose of general anesthetic 15, 21 and 30 days after surgery. The specimens were routinely processed by embedding in paraffin, serially cut and stained with H&E and Picrosirius and analyzed under light microscopy. The results showed evidence of a more advanced repair in the irradiated group when compared to the non-irradiated groups. The repair of the irradiated group was characterized by both increased bone formation and amount of collagen fibers around the graft within the cavity from the 15th day after surgery, also considering the osteoconductive capacity of the Gen-ox®. We conclude that LLLT had a positive effect on the repair of bone defects implanted with inorganic bovine bone.

The objective of this study was to investigate the distribution of CD8+ and CD20+ lymphocytes in chronic periapical inflammatory lesions. A total of 90 periapical inflammatory lesions (chronic abscesses, abscessed cysts, and inflammatory cysts) were evaluated. The biotin-streptavidin immunohistochemical technique was used to identify cytotoxic/suppressor T-lymphocytes (CD8) and B-lymphocytes (CD20). Age ranged from 10 to 67 years. Patients between 26 and 45 years old (54.4%), females (52.2%), and white patients (74.4%) were more frequently affected. CD8+ cell distribution was as follows: 1) fibrous capsule: diffuse in 58.8% of chronic abscesses and absent in 64.1% of abscessed cysts and in 70.6% of inflammatory cysts; 2) infiltration zone: diffuse in 100% of abscessed cysts and in 82.4% of inflammatory cysts; 3) sub-epithelial zone: absent in 53.0% of inflammatory cysts and diffuse in 56.4% of abscessed cysts; 4) suppurative zone: diffuse in 100% of chronic abscesses and in 97.5% of abscessed cysts. CD20+ cell distribution was as follows: 1) fibrous capsule: absent in 100% of inflammatory cysts, in 94.8% of abscessed cysts, and in 88.3% of chronic abscesses; 2) infiltration zone: diffuse in 100% of abscessed cysts and in 53% of inflammatory cysts; 3) sub-epithelial zone: absent in 58.8% of inflammatory cysts and focal in 46.2% of abscessed cysts; 4) suppurative zone: diffuse in 100% of abscessed cysts and in 100% of chronic abscesses. The distribution of the lymphocytic infiltrate in the lesions was usually diffuse for both types of lymphocytes.

The aim of this study was to determine the minimum inhibitory concentration (MIC) and antimicrobial effectiveness by the direct exposure test of 4 endodontic irrigants [1% sodium hypochlorite (NaOCl), 2% chlorhexidine (CHX), 1% calcium hydroxide (Ca(OH)2; prepared with 1 g of Ca(OH)2 and 100 mL of sterile distilled water), a solution of Ca(OH)2 + detergent (HCT20)] for S. aureus, E. faecalis, P. aeruginosa, B. subtilis, C. albicans and a mixed culture. Microbial growth was analyzed by two methods: turbidity of the culture medium that was confirmed by Gram stain and subculture in a specific nutrient broth. In the dilution test, NaOCl solution showed MIC equal to 0.1% for S. aureus, E. faecalis, P. aeruginosa and C. albicans and equal to 1% for B. subtilis and the mixed culture. CHX (2%) presented MIC equal to 0.000002% for S. aureus, 0.02% for E. faecalis, B. subtilis, C. albicans and the mixed culture and 0.002% for P. aeruginosa. Ca(OH)2 solution (1%) showed MIC greater than 1% for all the microorganisms except P. aeruginosa for which it was equal to 1%. Calcium hydroxide solution + detergent showed MIC equal to 4.5 mL for S. aureus, P. aeruginosa, B. subtilis, C. albicans and the mixed culture and greater than 4.5 mL for E. faecalis. In the direct exposure test, NaOCl had better antimicrobial effectiveness for all microorganisms at all times. CHX (2%) was effective for S. aureus, E. faecalis and C. albicans at all times, and ineffective for P. aeruginosa, B. subtilis and the mixed culture. The other solutions showed the worst results.

The relationship between metallic cast crowns and tensile strength according to cement types submitted to thermocycling was studied. Seventy-two metallic crowns were cast with Verabond II Ni-Cr alloy and cemented in standardized preparations with 10º tapering. Three types of finishing line (45-degree chamfered, 20-degree bevel shoulder and right shoulder) were made with diamond burs on bovine teeth. Twenty-four metallic crowns in each group were randomly subdivided into three subgroups of 8 samples each according to the cement used: SS White zinc phosphate cement, Vitremer resin-modified glass ionomer cement, and Rely X resin cement and were submitted to thermocycling. Retention was evaluated according to tensile load required to displace the metallic cast crowns from tooth preparations with an Instron testing machine. ANOVA and Tukey's test showed a statistically significant difference among luting materials, with greater results for Rely X resin cement (24.9 kgf) followed by SS White zinc phosphate cement (13.3 kgf) and Vitremer resin-modified glass ionomer cement (10.1 kgf). The finishing line types did not influence the tensile resistance of the crowns fixed with the three cements. Increased tensile resistance of metallic crowns fixed on bovine teeth was obtained with resin cement, independent of the finishing line types.

Several formulations of alternative alloys have been proposed for the substitution of gold-based alloys used in Dentistry. Recently, a Ni-Cr-Ti-based alloy has been introduced. The purpose of this work was to verify the marginal adaptation obtained with one-piece superstructures for implant-supported prostheses obtained in Ni-Cr-Ti alloy, compared to a semi-noble alloy Pd-Ag. Eight superstructures for each alloy were produced over 4 implants in the anterior region of the mandible. The superstructures were placed in a torquemeter and the fixation screw of implant #1 was tightened with a 20 Ncm load with the others loosened (Sheffield test). The unfitness (in mm) was measured using a three-dimensional optical measurer in each implant, in the buccal and lingual aspects. The obtained data were submitted to statistical analysis by the analysis of variance and Tukey's test at 5% level. Significant differences were found for the factors material (p<0.05), with Ni-Cr-Ti pieces better than Pd-Ag ones, and implants (p<0.01). There were no significant differences for the factor position and interactions among factors (p>0.05). Based on the analysis of the data, it is possible to conclude that the Ni-Cr-Ti alloy makes possible the obtainment of one-piece implant-supported superstructures with a smaller misfit compared to the one obtained in Pd-Ag alloy, traditionally indicated for this situation. Additional tests may verify the superiority of the Ni-Cr-Ti alloy.

Computed tomography (CT) has been increasingly used in the examination of patients with craniofacial trauma. This technique is useful in the examination of the temporomandibular joint and allows the diagnosis of fractures of the mandibular condyle. Aiming to verify whether the three-dimensional reconstructed images from CT (3D-CT) produce more effective visual information than the two-dimensional (2D-CT) ones, we evaluated 2D-CT and 3D-CT examinations of 18 patients with mandibular condyle fractures. We observed that 2D-CT and 3D-CT reconstructed images produced similar information for the diagnosis of fractures of the mandibular condyle, although the 3D-CT allowed a better visualization of the position and displacement of bone fragments, as well as the comminution of fractures. These results, together with the possibility of refining and manipulating perspectives in 3D images, reinforce the importance of its use in the surgical planning and evaluation of treatment. We concluded that 3D-CT presented supplementary information for a more effective diagnosis of mandibular condyle fractures.

The reliability of the linear tomography and panoramic radiography made with X-ray equipment was evaluated (Vera View Scope X-600; Morita). The sample was composed of 20 dry human hemimandibles, in which the area selected for analysis was 1.5 cm distal from the limit set before the mental foramen. Four measurements were made. The images obtained were drawn on acetate paper and the hemimandibles cut at the demarcated area. The measurements were made using a digital electronic pachymeter. The values found for the radiographic images were compared to those obtained in the mandibular specimens and submitted to statistical evaluation by the Wilcoxon test. It was concluded that both techniques were reliable for the accomplishment of vertical linear measurements in the selected area. However, a 2.0 mm safety margin is recommended.

The purpose of this study was to evaluate cardiovascular parameters during dental procedures: systolic, diastolic, and mean blood pressures, and heart rate. Nineteen healthy normotensive patients (18-56 years of age) received restorative treatment on three maxillary molars. The patients were continuously monitored by a non-invasive automatic monitor for blood pressure and heart rate during the pre-, trans-, and post-operative periods at the following stages: 15 min prior to anesthesia; during topical anesthesia; during infiltrative anesthesia; for 5 minutes immediately after; during cavity preparation; during restorative procedure; for 10 min after completion. Patients were divided into three groups: A (without pre-medication), B (preceded by 10 mg diazepam), and C (preceded by placebo). All patients received infiltrative anesthesia containing 1.8 mL of 2% lidocaine (36 mg) with epinephrine 1:100,000 (18 µg). There were no changes in the parameters during the clinical procedures. When groups were compared, there were significant differences in diastolic arterial pressures during anesthesia.

This work describes the knowledge and experience of dentists about cardiopulmonary resuscitation (CPR). A total of 182 dentists from São Paulo State, Brazil were interviewed: 59% judged themselves able to define CPR, although only 46% had a correct concept; 54% believed himself to be able to perform CPR, however, none of them referred to have received practical training in CPR; 3% of the interviewed professionals mentioned the occurrence of cadiopulmonary arrest in their dental office. It was concluded that dental surgeons in Brazil should be better trained for medical emergencies that can occur in the dental office.

Pilomatricomas are relatively rare tumors of ectodermal origin from the outer root sheath cell of the hair follicle. They are usually asymptomatic, solitary, firm or hard, freely mobile, dermal or subcutaneous nodules. The purpose of this article is to present a case that illustrates the diagnostic difficulty encountered by oral surgeons and pathologists and to review the literature regarding pilomatricomas of the auricular region.

The treatment of persistent bone defects has encouraged the search for proper techniques or bone substitutes. In Dentistry, a common problem in the treatment of periodontal bone defects is the growth of tissues within the lesion, such as the junctional epithelium, which impair regeneration of these tissues. Guided tissue regeneration (GTR), based on the separation of the tissues by means of membranes or barriers, was developed in an attempt to improve periodontal regeneration. The aim of this study was to histologically evaluate the tissue response to a membrane of demineralized bovine cortical bone implanted in the subcutaneous tissue of rats. The study periods were 1, 3, 7, 15, 30 and 60 days after implantation. Analysis of the histological sections demonstrated a moderate to intense inflammatory response at 1 and 3 days, moderate at 7 and 15 days, and almost absent at 30 and 60 days. Resorption of the membrane began 15 days after implantation, and at 60 days only remnants could be detected in some animals. We concluded that the demineralized bovine cortical bone membrane was well tolerated by the tissues and is completely resorbed after 30-60 days by mononuclear cells and multinucleated giant cells, which disappear upon completion of the process.

Oral lichen planus (OLP) is a chronic inflammatory disease with different clinical presentations that can be classified as reticular or atrophic-erosive. Sixty-two OLP patients were studied to evaluate the clinical-pathologic characteristics of their OLP lesions and to investigate possible differences in their biological behavior. The most common clinical presentation was the reticular type (62.9% vs 37.1%). Atrophic-erosive presentations showed significantly longer evolution (chi square=4.454; p=0.049), more extensive lesions (chi square=16.211; p=0.000) and more sites affected than reticular ones (chi square=10.048; p=0.002). Atrophic-erosive OLP was more frequently found on the tongue, gingiva and floor of the mouth. No statistically significant differences could be identified between reticular and atrophic-erosive clinical presentations in terms of age, sex, tobacco habit, plasma cortisol level and depth of inflammatory infiltrate. We concluded that the classification of OLP lesions as reticular vs atrophic-erosive is a simple, easy to use classification that can identify clinical presentations with different biological behavior.