Two-step impression for atrophic mandibular ridge

BACKGROUND: The clinical difficulties encountered while treating edentulous patients with atrophic mandibular ridges are legion. Capturing tissue details while making an impression of a resorbed mandibular ridge poses a great clinical challenge. Extending the denture bases adequately to cover all of the available supporting tissues is one of the prime requisite. Surgical approach is necessary only when the patient is incapable of wearing a conventional denture. This article describes a technique of making an impression of an atrophic mandibular ridge by the use of monophase and light-bodied impression material where surgical options such as implants, vestibuloplasty or ridge augmentation may not be feasible. This procedure results in improved stability and retention of the denture base.     

Data on dental bite materials with stability and displacement under load

It is of interest to document the accuracy, time dependent dimensional stability and displacement to load for 5 types of inter-occlusal recording materials. We used cad bite paste, putty, lab putty, pattern resin and poly tray acrylic material in this study. A total of 25 samples were fabricated to evaluate the accuracy and dimensional stability. The amount of displacement was calculated by applying displacing force on the bite registration materials till they fractured using Instron 3000 UTS machine. Statistical analysis of the data shows that CAD bite paste has the maximum amount of accuracy and dimensional stability whereas pattern resin showed the least amount of displacement to applied force. Thus, we report that CAD bite registration material displayed best results in terms of accuracy and dimensional stability and moderate results in terms of displacement to force.     

A novel approach to the distortion assessment of denture impression trays.

A novel method to treat and interpret distortion of denture impression trays has been proposed. When compared with the conventional method this approach, based on the general least squares principle, offers a significant advantage since the displacement for each individual point can be traced providing more profound insight into the character of the overall deformation itself. The method was applied to study dental impression trays manufactured of self-curing acrylic. The results indicate the existence of a large degree of individuality and non-uniform behaviour of a specific tray material. The method developed here can be applied to specimens of any arbitrary size and shape and it is not limited by the number of the reference points.     

Interpretation and impression of ambiguous eye gaze of a mother and child in a Japanese traditional picture

Using various compositions with alterations in figures' gaze directions and additions of an object, the interpretation of gaze directions and the impression of a figure were examined. The results obtained by factor analysis, cluster analysis, multi-dimensional scaling and questionnaires showed that 1) observers' impression of a figure was affected not only by figures' gaze directions but also by the presence or absence of an object viewed by figures, 2) compositions of joint attention gave a positive impression even if in an averted composition (parallel joint attention), 3) the pictures used here were viewed from the point of view of the attachment of mothers and the independence of children, and 4) a woman in this picture was evaluated from the aspect of a motherhood or pre-motherhood impression. These results are discussed in terms of the cognitive process of gaze directions as well as the developmental process of the mother-child relationship.     

Visualization and measurement of nanometer dimension surface features using dental impression materials and atomic force microscopy

The resolving ability of polyvinyl siloxane impression material at a submicron scale was tested in order to determine its ability to reproduce the topographical features of worn contact surfaces such as those found in the food processing industry. Three impression materials were tested against three surfaces with standardized surface features. Cryo scanning electron microscopy and atomic force microscopy were used to provide high magnification images of the surfaces and impressions of the surfaces. Dimensional information was also provided by surface profilometry techniques using a solid stylus and a laser profilometer. Although the three impression materials accurately reproduced the line spacing of the largest scale test specimen, the least viscous material gave the most satisfactory surface reproduction, although a degree of vertical relief was lost. This material has been used to monitor wear of food contact surfaces in situ. Such information enables further research into the effect of increased or altered substratum surface roughness upon microbial and organic soil retention.     

Preoperative brush and impression cytology in ocular surface squamous neoplasms

OBJECTIVE: Preoperative cytologic diagnoses of ocular surface squamous neoplasms were evaluated and compared with histologic diagnoses. STUDY DESIGN: Impression cytology (Millipore filter paper) and brush cytology were applied to 32 patients who had conjunctival neoplasms. Papanicolaou-stained cytologic preparations and hematoxylin and eosin-stained histologic sections were examined by light microscopy. RESULTS: The brush technique was used on 27 patients; impression cytology was applied in 5 cases. Cytologic and histologic diagnoses were concordant in 26 cases. Squamous cell carcinoma or carcinoma in situ was diagnosed in 18 and dysplasia in 4 cases. Squamous metaplasia and normal-appearing conjunctival epithelial cells were diagnosed cytologically in four cases; of those histologic diagnoses, one was pterygium and three, conjunctival nevus. Four cases revealed discrepancies between the cytologic and histologic preparations. There was one false positive result, and one case was subconjunctival invasion of basal cell carcinoma of the eyelid. CONCLUSION: Impression and brush cytology are fast, cost-effective, reliable and noninvasive diagnostic tools for ocular surface squamous neoplasms. However, the brush technique has several advantages over impression cytology.     

Diagnostic impression cytology: a simple technique for the diagnosis of external eye disease

Diagnostic impression cytology: a simple technique for the diagnosis of external eye disease
The technique of impression cytology was used for cytologic examination of conjunctival samples from 128 patients with a variety of external eye diseases. The method of sample collection and the staining procedure are described. Microscopic examination showed 62 cases with allergic conjunctivitis, 23 with bacterial or viral infection, 26 cases with changes typical of dry eye and 17 cases with non-specific chronic inflammation. The cytologic features and numerous applications of impression cytology are discussed.     

Electronic evaluation for video commercials by impression index

How to evaluate the effect of commercials is significantly important in neuromarketing. In this paper, we proposed an electronic way to evaluate the influence of video commercials on consumers by impression index. The impression index combines both the memorization and attention index during consumers observing video commercials by tracking the EEG activity. It extracts features from scalp EEG to evaluate the effectiveness of video commercials in terms of time–frequency-space domain. And, the general global field power was used as an impression index for evaluation of video commercial scenes as time series. Results of experiment demonstrate that the proposed approach is able to track variations of the cerebral activity related to cognitive task such as observing video commercials, and help to judge whether the scene in video commercials is impressive or not by EEG signals.     

两种排龈技术的临床效果比较

目的 比较排龈线与排龈膏两种排龈技术的临床使用效果,以确定排龈膏是否比排龈线更易于被患者和临床医师所接受和推广。方法 作者在对151例门诊患者198颗牙,行冠修复时,于取模过程中分别应用排龈线和排龈膏两种排龈技术,分别记录操作时间、观察印模效果及患者舒适度等。结果 两种排龈技术在印模效果上都取得良好效果,在操作的时间和产生的疼痛程度上有着明显的差异。结论 两种排龈技术均可减少牙体预备时对牙龈组织的损伤及出血,帮助取得清晰的印模,但排龈膏便捷的操作方式及无痛操作理念更易被患者及临床医师所接受。     

Tissue preparation for scanning electron microscopy of fruit surfaces: Comparison of fresh and cryopreserved specimens and replicas of banana peel

Epicuticular waxes, which are removed by conventional dehydration techniques, were present when observing fresh hydrated peel, cryopreserved peel and dental impression/epoxy resin replicas of the banana fruit (Musa sapientum). In all cases the replica technique gave accurate reproductions of the surface with the advantages of speedy preparation and non-destructive sampling. In addition, the replica technique, when compared with fresh samples, provided specimens which were durable with no time constraint. The replica technique is recommended for specimens which are difficult to observe and susceptible to collapse.     

Lateral orbitofrontal cortex involvement in initial negative aesthetic impression formation

It is well established that aesthetic appreciation is related with activity in several different brain regions. The identification of the neural correlates of beauty or liking ratings has been the focus of most prior studies. Not much attention has been directed towards the fact that humans are surrounded by objects that lead them to experience aesthetic indifference or leave them with a negative aesthetic impression. Here we explore the neural substrate of such experiences. Given the neuroimaging techniques that have been used, little is known about the temporal features of such brain activity. By means of magnetoencephalography we registered the moment at which brain activity differed while participants viewed images they considered to be beautiful or not. Results show that the first differential activity appears between 300 and 400 ms after stimulus onset. During this period activity in right lateral orbitofrontal cortex (lOFC) was greater while participants rated visual stimuli as not beautiful than when they rated them as beautiful. We argue that this activity is associated with an initial negative aesthetic impression formation, driven by the relative hedonic value of stimuli regarded as not beautiful. Additionally, our results contribute to the understanding of the nature of the functional roles of the lOFC.     

Environmental lead and children's intelligence: a systematic review of the epidemiological evidence.

OBJECTIVE--To quantify the magnitude of the relation between full scale IQ in children aged 5 or more and their body burden of lead. DESIGN--A systematic review of 26 epidemiological studies since 1979: prospective studies of birth cohorts, cross sectional studies of blood lead, and cross sectional studies of tooth lead. SETTING--General populations of children > or = 5 years. MAIN OUTCOME MEASURES--For each study, the regression coefficient of IQ on lead, after adjustment for confounders when possible, was used to derive the estimated change in IQ for a specific doubling of either blood or tooth lead. RESULTS--The five prospective studies with over 1100 children showed no association of cord blood lead or antenatal maternal blood lead with subsequent IQ. Blood lead at around age 2 had a small and significant inverse association with IQ, somewhat greater than that for mean blood lead over the preschool years. The 14 cross sectional studies of blood lead with 3499 children showed a significant inverse association overall, but showed more variation in their results and their ability to allow for confounders. The seven cross sectional studies of tooth lead with 2095 children were more consistent in finding an inverse association, although the estimated magnitude was somewhat smaller. Overall synthesis of this evidence, including a meta-analysis, indicates that a typical doubling of body lead burden (from 10 to 20 micrograms/dl (0.48 to 0.97 mumol/l) blood lead or from 5 to 10 micrograms/g tooth lead) is associated with a mean deficit in full scale IQ of around 1-2 IQ points. CONCLUSION--While low level lead exposure may cause a small IQ deficit, other explanations need considering: are the published studies representative; is there inadequate allowance for confounders; are there selection biases in recruiting and following children; and do children of lower IQ adopt behaviour which makes them more prone to lead uptake (reverse causality)? Even if moderate increases in body lead burden adversely affect IQ, a threshold below which there is negligible influence cannot currently be determined. Because of these uncertainties, the degree of public health priority that should be devoted to detecting and reducing moderate increases in children''s blood lead, compared with other important social detriments that impede children''s development, needs careful consideration.     

An analysis of cercopithecoid odontometrics. I. The scaling of the maxillary dentition.

The relations between two tooth indices, post-canine area and incisor width in the upper jaw, and three variables, diet, body weight and body weight dimorphism, were examined separately for the males and females of 29 cercopithecoid species. Each species was assigned to one of three diet classes (folivore, frugivore, omnivore). Data on the other variable consisted of species means (log-transformed) obtained from published sources. The analytic techniques used were bivariate and multiple regression, the tooth indices being the dependent variables. All tooth indices scaled isometrically within diet classes, and all except female incisor width scaled with positive allometry across diet classes. In both sexes, the body weight adjusted mean incisor width of folivores was significantly smaller than that of either frugivores or omnivores. In the females, the body weight adjusted mean post-canine areas did not differ significantly across diet classes, while in the males the omnivores had a larger body weight adjusted mean post-canine area than either the folivores or frugivores. Female post-canine area was the only tooth index for which body weight dimorphism was a significant predictor. Extrapolations of these findings to other extant and to fossil primate species are discussed.     

Conjunctival impression cytology in contact lens wearers

The upper tarsal conjunctiva is in constant friction with the surface of the contact lens. The conjunctival surfaces of 80 soft and gas-permeable contact lens wearers (40 each) and 20 controls were studied using biomicroscopy and impression cytology. A filter dissolution technique was used to process the conjunctival imprints. Biomicroscopic and cytologic grading of the conjunctivae was performed using four-tier grading systems. Impression cytology is a non-invasive, painless procedure. The altered technique of processing yielded better cellularity and excellent cellular detail. On biomicroscopy and cytology, all controls showed Grade 1 appearances. Soft lens wearers who were symptomatic were found to have a significant increase in both biomicroscopic and cytologic grades, when compared with their asymptomatic counterparts. No correlation was found between duration of lens use and biomicroscopic or cytologic grades. All changes were found to be more severe in soft lens wearers.     

Post-pleistocene reductions in human dental structure: a reappraisal in terms of increasing population density

This paper discusses the well-documented acceleration which occurred in the reduction of human dental structure during the post-Pleistocene. It suggests that the process can be explained in terms of different but related factors inherent in a transition from late-Pleistocene hunting and gathering conditions to ones involving a sedentary life in larger groups. It is postulated that directional selective forces acting during Upper Paleolithic to maintain large tooth size had only a poor influence and that the new techniques in food preparation had little or no effect. The phenomenon is seen as a possible side-effect of a more complex overall reduction in body size, of which dental reduction only represents a small but demonstrable part. It is also suggested that stresses may have played an important role in producing a transitory reduced dimensional expression of the genetic background. An interaction between the variables directly or indirectly affecting body mass is shown in the model proposed which relates to post-Pleistocene. An increase in population density is indicated as being the most decisive biological factor in determining the acceleration in the trend towards reduction. A preliminary version of this paper was presented at the Symposium on Upper Paleolithic/Mesolithic of Europe and the Mediterranean Basin, Pisa, September 8–10, 1984.     

Fish health assessment: a preliminary report on the use of impression smears of skin mucus

Preliminary results from this study suggest that impression smears of the skin mucus of fish can be used to aid in the evaluation of the fish's health status. Nonstressed Lagodon rhomboides and Carassius auratus have numerous superficial epithelial cells, occasional lymphocytes and other mononuclear cells in their cutaneous mucus. Smears of these fish 24 h post-stress had more cellular debris, micro-organisms and erythrocytes when compared to those made pre-stress. Components in the mucus of fish which recovered gradually became normal. Smears of fish, which died, had increasing amounts of debris and micro-organisms. The use of this relatively nontraumatic technique may be a useful adjunct in monitoring fish health.     

Comparison of most probable number and pour plate procedures for isolation and enumeration of sulphite-reducing Clostridium spores and group D faecal streptococci from oysters

A comparative study of methods to enumerate sulphite-reducing Clostridium spores and Group D faecal streptococci in oysters demonstrated that pour plate solid agar techniques gave higher counts than liquid broth most probable number procedures. Reinforced clostridial broth with supplements to detect sulphite reduction was compared with pour plates of egg yolk-free tryptose sulphite cycloserine agar incubated at 37 degrees C for 24 h. Azide dextrose broth was compared with pour plates using Slanetz and Bartley (SB) agar or KF-streptococcus agar at 37 degrees C. Most probable number procedures used for both groups of organisms gave excessive numbers of improbable tube combinations. For enumeration of Group D faecal streptococci, a pour plate technique using SB agar incubated at 37 degrees C for 48 h is recommended.     

Accuracy in Dental Medicine,A New Way to Measure Trueness and Precision

Reference scanners are used in dental medicine to verify a lot of procedures. The main interest is to verify impression methods as they serve as a base for dental restorations. The current limitation of many reference scanners is the lack of accuracy scanning large objects like full dental arches, or the limited possibility to assess detailed tooth surfaces. A new reference scanner, based on focus variation scanning technique, was evaluated with regards to highest local and general accuracy. A specific scanning protocol was tested to scan original tooth surface from dental impressions. Also, different model materials were verified. The results showed a high scanning accuracy of the reference scanner with a mean deviation of 5.3 ± 1.1 µm for trueness and 1.6 ± 0.6 µm for precision in case of full arch scans. Current dental impression methods showed much higher deviations (trueness: 20.4 ± 2.2 µm, precision: 12.5 ± 2.5 µm) than the internal scanning accuracy of the reference scanner. Smaller objects like single tooth surface can be scanned with an even higher accuracy, enabling the system to assess erosive and abrasive tooth surface loss. The reference scanner can be used to measure differences for a lot of dental research fields. The different magnification levels combined with a high local and general accuracy can be used to assess changes of single teeth or restorations up to full arch changes.     

Comparison of most probable number and pour plate procedures for isolation and enumeration of sulphite-reducing Clostridium spores and Group D faecal streptococci from oysters

A comparative study of methods to enumerate sulphite-reducing Clostridium spores and Group D faecal streptococci in oysters demonstrated that pour plate solid agar techniques gave higher counts than liquid broth most probable number procedures. Reinforced clostridial broth with supplements to detect sulphite reduction was compared with pour plates of egg yolk-free tryptose sulphite cycloserine agar incubated at 37°C for 24 h. Azide dextrose broth was compared with pour plates using Slanetz and Bartley (SB) agar or KF-streptococcus agar at 37°C. Most probable number procedures used for both groups of organisms gave excessive numbers of improbable tube combinations. For enumeration of Group D faecal streptococci, a pour plate technique using SB agar incubated at 37°C for 48 h is recommended.     

Technical note: Morphometric maps of long bone shafts and dental roots for imaging topographic thickness variation

Qualitative and quantitative characterization through functional imaging of mineralized tissues is of potential value in the study of the odontoskeletal remains. This technique, widely developed in the medical field, allows the bi‐dimensional, planar representation of some local morphometric properties, i.e., topographic thickness variation, of a three‐dimensional object, such as a long bone shaft. Nonetheless, the use of morphometric maps is still limited in (paleo)anthropology, and their feasibility has not been adequately tested on fossil specimens. Using high‐resolution microtomographic images, here we apply bi‐dimensional virtual “unrolling” and synthetic thickness mapping techniques to compare cortical bone topographic variation across the shaft in a modern and a fossil human adult femur (the Magdalenian from Chancelade). We also test, for the first time, the possibility to virtually unroll and assess for dentine thickness variation in modern and fossil (the Neanderthal child from Roc de Marsal) human deciduous tooth roots. The analyses demonstrate the feasibility of using two‐dimensional morphometric maps for the synthetic functional imaging and comparative biomechanical interpretation of cortical bone thickness variation in extant and fossil specimens and show the interest of using this technique also for the subtle characterization of root architecture and dentine topography. More specifically, our preliminary results support the use of virtual cartography as a tool for assessing to what extent internal root morphology is capable of responding to loading and directional stresses and strains in a predictable way. Am J Phys Anthropol, 2010. © 2010 Wiley‐Liss, Inc.