Assessment of facial asymmetries from posteroanterior cephalograms: validity of reference lines.

The goal of this study was to determine the ability of various horizontal and vertical reference lines to provide measurements of dentofacial asymmetries from posteroanterior (PA) cephalograms. Ten horizontal and 15 vertical reference lines, including best-fit lines and lines most commonly used in PA analysis, were tested. A model of a dry skull was devised to create 30 asymmetric positions of the maxillomandibular complex. The true transverse and vertical asymmetries were calculated based on measurements of changes in the position of 24 dental and skeletal landmarks. A PA cephalogram was obtained for each asymmetric position. The horizontal and vertical reference lines were constructed on each PA cephalogram, and measurements of transverse and vertical asymmetries were obtained relative to the individual reference lines. Linear regression analyses were used to compare the actual asymmetries with those measured cephalometrically, relative to the individual reference lines. The adjusted R(2) values for all 10 horizontal lines indicated excellent agreement between the true asymmetries and the measured vertical asymmetries. Ten vertical lines accurately represented transverse asymmetry. Vertical lines constructed between 2 midline points, with 1 point located on the lower part of the skull, were not valid. The best-fit line and all lines constructed as perpendiculars through midpoints between pairs of orbital landmarks showed excellent validity. Crista galli-anterior nasal spine and nasion-anterior nasal spine had the lowest validity and should not be used in cephalometric analysis of asymmetries. The position of anterior nasal spine will be altered in facial asymmetry involving the maxilla.     

The panoramic X-ray as a detector for preventing maxillary canine impaction

The dental pantomogram (DPT) is a common diagnostic tool in today's dental offices and is effectively used by dental practitioners in the diagnosis of dental caries, periodontal disease, bone pathology, jaw fractures, hard tissue anomalies as well as the detection of missing and impacted teeth. This paper discusses specific radiographic findings in the mixed dentition that can be possible impaction indicators. When these indicators are properly utilized, we can often prevent impaction of the maxillary canine and associated resorption of the maxillary incisor root. Diagnostic radiographic information will be discussed and analyzed on two sisters to demonstrate contrasting end treatment results.     

The gothic arch tracing and the upper canine teeth as guides in the positioning of upper posterior teeth

The relationship between the position of the buccal cusps of the natural upper posterior teeth and the distance between the lateral arms of the Gothic arch tracing or the distance between the upper canine teeth has been found to be constant to within +/- 2 mm. This may be of value when setting up artificial teeth for denture patients, enabling them to be positioned close to the natural predecessors.     

Statistical analysis of data derived from clinical variables of plaque and gingivitis

Abstract. Selection of suitable subjects and statistical analysis of data derived from clinical trials presents a number of problems. In this trial, clinical data were analysed separately for pooled whole mouth data and for data including positive scores only for the variables of dental plaque and gingivitis. It was demonstrated that comparable data sets and statistical analyses were obtained using both data sets. Furthermore, it was shown that in order to achieve the best possible results in a clinical trial, the variable of gingivitis should be used in preference to plaque scores, that only individuals of high and/or moderate susceptibility to inflammation should be selected for inclusion in the statistical analysis, and that sites which have positive signs of disease only, should be included in the statistical analysis.     

Calcium silicate coating derived from Portland cement as treatment for hypersensitive dentine

OBJECTIVES: To evaluate the in vitro effectiveness on dentine permeability and dentine morphology of a calcium silicate treatment based on Portland cement (DSC). METHODS: The experimental treatment consisted of a calcium silicate paste based on Portland cement that was applied on dentine surface for 3 min. A professional re-mineralizing treatment (GC Tooth Mousse), two in office desensitizing agents (D/Sense Crystal, and By Sealant) and a commercial toothpaste Dentosan S were studied as comparison materials. All materials were applied accordingly with manufacturer directions on wet dentine. The quantitative changes in the hydraulic conductance i.e., permeability through tubules of dentine discs samples produced by treatment were quantified in vitro using a hydrostatic device working at 6.9 kPa. SEM/EDX analyses of dentine were carried out to obtain qualitative information on dentine morphology and surface deposits and to study their relationship with the hydraulic conductance. After treatment, each dentine sample was immersed in artificial saliva and permeability re-evaluated. Finally, each sample was exposed to 0.02 M citric acid solution and the final permeability was assessed. RESULTS: The experimental treatment and both oxalate-based products (D/Sense Crystal and By Sealant) significantly decreased dentine permeability and created crystals and precipitates on the dentine surface that reduced the diameter of dentinal tubules. Artificial saliva immersion and citric acid challenge increased dentine permeability and partially modified the treated surfaces. Dentosan S and GC Tooth Mousse treatments partially reduced dentine permeability and created small amount of precipitates that were removed by saliva immersion and citric acid exposure. EDX revealed the presence of calcium-rich layer after DSC experimental treatment. CONCLUSIONS: The application of the experimental calcium silicate paste and oxalate-based treatments was determined to be effective on dentine permeability reduction and tubules occlusion. The clinical use as desensitizing agent of materials derived from Portland cement as desensitizing agent should be considered for dentine hypersensitivity treatment.     

Personality variables as predictors of performance for first-year dental students

This study attempted to determine if students with certain personality preferences outperform others over the course of the initial dental school year. The Myers-Briggs Type Indicator (MBTI) was used to assess the relationship between personality preferences and academic performance. One hundred and ninety-nine dental students in four successive first-year classes, 1983-86, participated. Pearson correlation coefficients were used to relate academic performance (first-semester, second-semester, and first-year GPAs) to personality preferences (EI, SN, TF, JP) and academic predictors (entering GPA and DAT scores). For personality preferences, all correlation coefficients were low and nonsignificant. In comparison, entering GPA and DAT (academic) scores were significantly correlated with first-semester, second-semester, and first-year GPAs. DAT (perceptual ability) scores showed a significant correlation with first-semester GPAs only.     

Developmental movements of the inner enamel epithelium as derived from micromorphological features

It was the purpose of this article to analyze the (micro) morphological structure of enamel at different stages of development in order to deduce movement patterns of ameloblasts during formation of the human dental primordium. Developing enamel and overlying ameloblasts were dried and fractured for scanning electron microscopy (SEM) and sectioned for transmission electron microscopy (TEM). Specimens of human permanent enamel were either fractured and/or ground and etched to visualize the enamel rods. All specimens were viewed by SEM. Moreover, three-dimensional reconstructions were made from serial ground sections of enamel blocks to follow the enamel rods for a longer distance. In addition, the outline of the dentino–enamel junction was analyzed under the SEM after removal (using nitric acid) of the enamel cap, and in serial histological sections. Two basic movements of the inner enamel epithelium can be derived from the micromorphological features: (i) the scalloped dentino–enamel junction may be a consequence of a bulged inner enamel epithelium owing to initial spatial impediment; and (ii) the undulating path of the enamel rods may be a consequence of unequal growth of the cells in the cervical loop.     

唾液蛋白作为低龄儿童龋预测标志物的研究进展

低龄儿童龋(ECC)进展迅速,早期诊断困难,严重影响儿童的身心健康.实现对龋高危儿童的早期预测和预防干预是控制ECC的有效手段.随着蛋白质组学技术的发展,唾液蛋白正展现出用于疾病预测和早期诊断的强大优势.唾液蛋白通过多种天然防御机制调节口腔微生态环境,在ECC的控制中发挥重要作用;其水平高低与宿主龋易感性相关,是潜在的...     

Clinical and pharmacological variables as a risk factor for nifedipine-induced gingival overgrowth

BACKGROUND: Gingival enlargement is usually noted within one to two months after the initiation of nifedipine therapy. The aetiology of nifedipine-induced gingival overgrowth is uncertain. The aim of this study was to determine the relationship between plasma and gingival crevice fluid (GCF) nifedipine concentrations and the degree of gingival overgrowth in patients treated with nifedipine, and also to assess the correlations between clinical and pharmacological variables. METHODS: Eighteen patients taking nifedipine in regular doses for at least six months participated in the study. Gingival enlargement was evaluated with two indices to score vertical and horizontal overgrowth. Gingival index (GI), plaque index (PI), gingival bleeding time index (GBTI), probing depth (PD) and clinical attachment level (CAL) were also evaluated. GCF and plasma nifedipine concentrations were determined by using high performance liquid chromatography. RESULTS: There was no significant difference between responders and non-responders for PI, GI and GBTI. The mean concentration of nifedipine in GCF was significantly greater than concentration in plasma. No significant difference was observed for GCF and plasma nifedipine concentration between responders and non-responders. CONCLUSIONS: The present study showed that neither GCF nor plasma nifedipine levels appeared to be a risk factor for nifedipine-induced gingival overgrowth. Improving the oral hygiene in patients using nifedipine may help control the degree of drug-induced gingival enlargement.