Effects of phosphoric acid on bovine enamel bleached with carbamide peroxide

The aim of this study was to measure the demineralization capacity of 37% phosphoric acid on bovine enamel at different time-points after bleaching with 30% carbamide peroxide. Five, 4 × 4-mm sections were obtained from the enamel of 10 bovine incisors. After applying 30% carbamide peroxide (Vivastyle) for 90 min, specimens were stored in artificial saliva for 0, 24, 72 h, or 7 d and then immersed in 37% phosphoric solution. At 15, 30, 60, 90, and 120 s, 5-ml aliquots were extracted. A control group of specimens was not bleached. Ca²⁺ concentrations were measured by atomic absorption spectrophotometry. A larger amount of Ca²⁺ was extracted from enamel by phosphoric acid after the application of 30% carbamide peroxide. Twenty-four hours after bleaching, significantly more Ca²⁺ was extracted from bleached than from control specimens at all time-points, and this greater susceptibility to the action of the acid persisted for at least 1 wk after bleaching.     

A study of the septa in the maxillary sinuses and the subantral alveolar processes in 30 patients

The objective of this paper is to study the incidence of septa in the maxillary sinus and measure the height of the underlying alveolar process using panoramic radiography and computerized tomography (CT scans). Thirty patients who were going to be treated with dental implants were submitted to panoramic radiographs and CT scans. Sixty maxillary sinuses were analysed and divided into 2 groups: group 1 (totally edentulous) and group 2 (partially edentulous). The sinuses were divided into 3 regions (anterior, middle, and posterior), the septa were analysed, and the heights of the alveolar processes were calculated in these 3 areas. Of the 30 patients, 36.5% had maxillary sinuses, and 25% of these sinuses had septa, and 11.8% of the panoramic radiographs were false-negatives. In the panoramic radiographs of 10 patients, 3 had bilateral septa, 5 had a septum in only one sinus, and 2 patients had 2 unilateral septa. In the CT scans of 11 patients, 4 patients had a bilateral septa, 5 had a septum in only 1 sinus, and 2 patients had 2 unilateral septa. Therefore, 2 more septa were observed in the CT scans. In the study of the height of the subantral alveolar process, the least amount of difference between both techniques occurred in the middle region of the sinus. The CT scan is more reliable than the panoramic radiograph in diagnosing maxillary septa because of its greater accuracy. In the panoramic radiograph, the middle portion of the alveolar process in the posterior subantral segment was the least distorted of the three portions measured.     

婴幼儿血管瘤继发组织坏死的临床研究

本文通过对65例血管瘤中的5例继发组织坏死的血管瘤进行血清雌二醇水平(E2)测定、肥大细胞计数,发现其血清E2水平及肥大细胞计数都明显高于正常对照组。经强的松及平阳霉素治疗后坏死的溃疡面愈合,并且血管瘤体积缩小,颜色明显变浅。     

Peripheral T-cell subsets in patients with reticular and atrophic-erosive oral lichen planus

OBJECTIVE: Oral lichen planus (OLP) presents with various clinical forms that can be classified into 2 major types: reticular OLP and atrophic-erosive OLP. Our objective was to investigate immunologic differences between these 2 types. STUDY DESIGN: We investigated possible immunologic differences between 26 patients with reticular OLP and 26 patients with atrophic-erosive OLP. RESULTS: No differences were detected in serum Ig levels or complement levels. However, the mean proportions of CD4+CD45RO+ and DR+ lymphocytes were significantly higher in patients with atrophic-erosive OLP than in patients with reticular OLP, whereas the mean proportion of CD8+CD45RA+ lymphocytes was significantly lower in patients with atrophic-erosive OLP. CONCLUSION: These findings suggest that the 2 clinical types of OLP might have different immunopathogenic mechanisms.     

Trigeminal neuropathy

Trigeminal neuropathies (TNs) are well recognized disorders characterized and manifesting as skin and mucosal numbness in the region innervated by the trigeminal nerve. Facial numbness indicates trigeminal sensory alteration affecting the trigeminal system. TNs always pose differential location difficulties as multiple diseases are capable of producing them: they can be the result of traumatism, tumors, or diseases of the connective tissue, infectious or demyelinating diseases, or may be of idiopathic origin. Their importance is explained by the fact that TN may represent the first manifestation of tumor disease, or of relapse in patients with prior neoplastic processes. As such, these manifestations are ominous, and patient life expectancy is often short. The clinical exploration reveals a loss of sensitivity in the cutaneous territory corresponding to the affected nerve, which can be partial (hypoesthesia) or complete (anesthesia). The sensory defect is occasionally associated with hyperesthesia (i.e., the patient suffers a decrease in sensory perception, but when sensation is perceived, it may cause considerable discomfort). Complementary studies are needed to establish the etiologic diagnosis, with laboratory tests to discard the possible causative diseases underlying the trigeminal neuropathy, and the opportune radiographic examinations in the form of plain X-rays or a routine cranial computed tomography scan.     

Evaluation of minipigs as an animal model for alveolar distraction

OBJECTIVE: Alveolar distraction osteogenesis is a relatively novel tissue regeneration technique that remains, in some respects, at an experimental stage. The selection of an experimental animal biomodel is not clearly defined, with reports in the reviewed literature on dogs, sheep, and monkeys. The present objective was to compare 2 experimental biomodels (dog and minipig) using an alveolar distraction protocol with a novel prototype distractor. STUDY DESIGN: Three beagle dogs and 3 G?ttingen minipigs were evaluated, placing the distractor at the right hemimandible alveolar ridge after previous extraction of premolars. The radiological examination was carried out immediately after the distraction and at 2 weeks of consolidation. RESULTS: Satisfactory clinical and radiological results were obtained in 2 of 3 beagle dogs after the previous unilateral extraction of mandibular and maxillary premolars. During the consolidation, a height gain of approximately 5 mm was observed, with the appearance of radiodense bone trabeculae in the distraction chamber. The distraction failed in all of the minipigs. CONCLUSION: The minipig was not an appropriate biomodel for the study of alveolar distraction because the investigators were not able to maintain the seal of the distraction chamber or the stability of the distractor.     

Analysis of an impedance function of zinc anodic dissolution

Zinc anodic dissolution has been studied by means of electrochemical impedance spectroscopy (EIS). The kinetic study of the oxidation mechanism has allowed us to propose a theoretical impedance function for this system in deaerated sulphate medium. Relevant information on the faradaic process is provided by analysis of the theoretical impedance function. Kinetic parameters of this system can be calculated from the fitting of experimental data to the faradaic impedance function deduced theoretically. The physical measurements of this function are analysed by means of the dependence of simulated EIS spectra on kinetic parameters.     

Periodontitis as risk factor for acute myocardial infarction. A case control study of Spanish adults

OBJECTIVE: The present study was designed to determine, in a case-control study of a Spanish population, whether periodontitis is a risk factor for acute myocardial infarction. BACKGROUND: Although part of cardiovascular risk could be explained by periodontal disease, available meta-analyses find significant heterogeneity and recommend the need for further observational and intervention studies. METHODS: A case-control study was conducted of 149 Spanish patients aged between 40 and 75 years, with 72 cases (acute myocardial infarction) and 77 controls (trauma patients). Periodontitis was measured as the percentage of sites with clinical attachment loss greater than 3 mm. A multivariate logistic regression model was constructed to estimate the adjusted effect of periodontitis on acute myocardial infarction, after considering the potential confounding effect of a large pool of risk factors. RESULTS: In a bivariate analysis, males, older patients, smokers, and those with hypertension, diabetes or hypercholesterolemia, showed an increased risk of acute myocardial infarction. The cases, compared to controls, showed worse results for all periodontal variables studied: gingival retraction, pocket depth, and periodontitis. The final multiple logistic model included sex, age, tobacco habit, hypertension, diabetes, hypercholesterolemia, regular exercise, and periodontitis. The association between periodontitis (dichotomized) and acute myocardial infarction was high and significant in both the unadjusted (odds ratio = 4.42, p < 0.001) and adjusted analyses (odds ratio = 3.31, p = 0.005). CONCLUSION: There is evidence of an association between periodontitis and acute myocardial infarction after adjusting for well-known risk factors for acute myocardial infarction.     

Fixed rehabilitation of a patient with hypohidrotic ectodermal dysplasia using zygomatic implants

We found few references in the dental literature on implant rehabilitation of patients with hypohidrotic ectodermal dysplasia and only 1 case on zygomatic fixations and maxillary prosthesis in a patient with hypohidrotic ectodermal dysplasia. Two zygomatic fixations were placed according to the sinus slot technique, together with 3 implants in the anterior maxillary region. After 6 months, an upper complete prosthesis was screwed onto the implants, and lower overdentures were placed over the remnant canines. After 18 months of follow-up the patient reported important improvement in oral function and self-esteem.