Tongue Structures Research Articles

How hydrocolloids affect the temporal oral perception of ice cream

In-mouth texture largely determines the acceptability of ice cream, making it a key quality factor. Its perception involves movements of the tongue and other oral structures while the product melts and becomes a smooth, creamy viscous liquid as its temperature increases. Time is therefore an important issue in the sensory perception of ice cream, but has barely been considered in ice cream evaluation. In the present work, six ice cream samples with very different textures, formulated with milk, cream, egg, and hydrocolloids, were analysed by the Temporal Dominance of Sensations (TDS) method. Iciness, coldness, creaminess, roughness, gumminess, and mouth coating were assessed. Hydrocolloids (and cream or egg to a lesser extent) modulated the temporal perception of ice cream attributes, reducing the first impact of sensations such as iciness and coldness. They also favoured an early perception of creaminess. Dynamic perception techniques combined with consumer sensory description by CATA (Check-all-that-apply) and liking scoring techniques gave a better understanding of which attributes drive consumer liking in relation to ice cream consumption.

Construction of Arnold tongue structures for coupled periodic oscillators

Abstract Arnold tongue structures generated due to the mutual entrainment of two periodic oscillators are studied experimentally and numerically. This mutual entrainment is provoked due to the mutual (bidirectional) coupling between the two oscillators. In experiments, this bidirectional coupling is achieved by immersing a pair of anodes (oscillators) in a common electrolytic solution. A voltage mismatch between these anodes renders the time period of the uncoupled oscillators non-identical. Moreover, the coupling strength between the two oscillators is uniquely determined by the Euclidean distance separating them. Systematically varying the distance between these two anodes as a function of their voltage mismatch, phase locked domains were located. Subsequently, Arnold tongue structures were constructed in the experiments. Numerical simulations, using a model for electrochemical corrosion, corroborate our experimental findings.

PERIODICALLY FORCED PIECEWISE-LINEAR ADAPTIVE EXPONENTIAL INTEGRATE-AND-FIRE NEURON

Although variability is a ubiquitous characteristic of the nervous system, under appropriate conditions neurons can generate precisely timed action potentials. Thus considerable attention has been given to the study of a neuron's output in relation to its stimulus. In this study, we consider an increasingly popular spiking neuron model, the adaptive exponential integrate-and-fire neuron. For analytical tractability, we consider its piecewise-linear variant in order to understand the responses of such neurons to periodic stimuli. There exist regions in parameter space in which the neuron is mode locked to the periodic stimulus, and instabilities of the mode locked states lead to an Arnol'd tongue structure in parameter space. We analyze mode locked solutions and examine the bifurcations that define the boundaries of the tongue structures. The theoretical analysis is in excellent agreement with numerical simulations, and this study can be used to further understand the functional features related to responses of such a model neuron to biologically realistic inputs.

Periodically stimulated piecewise linear adaptive exponential integrate-and-fire neuron

Although variability is a ubiquitous characteristic of the nervous system, under appropriate conditions neurons can generate precisely timed action potentials. Thus considerable attention has been given to the study of a neuron's output in relation to its stimulus. Frequency selectivity of mode locking exhibits in clinical studies of human cardiorespiratory systems [1], experimental sensory processing in the auditory nerve [2] and hair cells in cochlea [3], and experimental brain study in thalamocortical relay neuron response [4]. To understand the mechanisms behind these functional features, spiking neuron models are used in studying the precise timing of firing events that is thought to underlie the frequency mode locking. In this study, we consider an increasingly popular model, the adaptive exponential integrate- and-fire (aEIF) neuron, and, for analytical tractability, its piecewise linear variant is adopted to understand the responses of such neurons to periodic stimuli. We construct general solutions of arbitrary mode locked states driven by a sinusoidal external stimulus, and describe their stability by the maximal Lyapunov exponent. We find period-doubling and saddle-node bifurcations of mode locked solutions, and the instabilities of the mode locked states lead to a so-called Arnol'd tongue structure in parameter space (Figure ​(Figure11 shown in input amplitude versus current), with p:q denoting the neuron firing p times for every q periods of the stimuli (Figure ​(Figure1B).1B). An interesting aspect of this model that is unaware of occurring elsewhere, is that if the amplitude of periodic stimulus is sufficiently large, solutions can enter different regions of phase space (switching manifold) multiple times between firing. Significant parts of the boundaries of Arnol'd tongues are defined by saddle-node bifurcations of such solutions (marked as red in Figure ​Figure11). Figure 1 (A) Various bifurcations shown in 1:1 phase locked solutions. PD: Period-doubling; sn1: saddle-node in switching manifold once; sn3: saddle-node in switching manifold three times, 1 → 3, transition from sn1 to sn3. (B) Frequency mode locked solutions ... The aEIF model includes a subthreshold and a spike-triggered adaptation parameters which can be related to the M-current and the afterhyperpolarization current, respectively, both producing spike-frequency adaptation. We observe similar tongue structures when either adaptation value is increased. It consists with the finding shown [5] that higher values of input current are required to maintain the same spiking frequency with an increase of either adaptation parameter. The theoretical analysis is in excellent agreement with numerical simulations, and this study can be used to further understand the functional features related to responses of such neurons to biologically realistic stimuli.

Iranian EFL Learners’ Attitudes toward Correction of Oral Errors

1. IntroductionAs many language educators and researchers (e.g., Edge, 1989; Hendrickson, 1987 as cited in Katayama 2007) maintain, making errors is a necessary and natural process of language learning. Inevitably, learner errors and feedback to errors have been of great interest to language teachers and researchers. And in this regard EFL learner's attitude toward the error correction is of outmost importance and it can facilitate the language learning process.It is important to understand that learners have different preferences, that is to say styles in the way they like to be corrected. Some students favor a focus on form, while others do not. Teaching methods differ as well. Some teachers tend to correct all the errors while some tend to be tolerant and still some others do not correct at all (Riazi and Riasti, 2007; Noora, 2006). According to the relevant literature on teachers' and students' preferences and attitudes towards error correction, many studies show that while teachers and students share such common views as the importance of error correction and the types of errors that require correcting, there exist considerable differences as to the techniques of error correction (Lee, 2005; Wang, 2010).While there are considerable number of studies that focus on the issue of error correction and error analysis, relatively few studies have been carried out related to EFL learner's attitude toward error correction methods during the class time (i.e. especially in Iran context). But it is believed that in order to have a successful learning and teaching process it is necessary to consider EFL learners' perceptions. The role of correction in language teaching has been an issue for quite some time and opinions vary as to whether correction is effective or not. For the time being, people rarely consider the learners' perception on oral error correction. And that is why it is necessary to do research associated with their opinion about oral error correction.1.1. Related review of literatureOn the related literature of error and error correction, it becomes clear that learning and teaching process is significantly bound with the way teachers and learners react toward the errors and how they try to correct them. Before correcting errors language teachers need to consider the cause of errors. As it has been suggested, errors may occur in three types of cases (Chastain 1988). First, some errors occur because learners are not aware of the rules. Second, some errors creep into student's language because they do not attach any great importance to linguistic accuracy. Third, some errors result from temporary overload on the student's cognitive processes due to fatigue, embarrassment, illness, and so on. Correction in the first case will be beneficial, if the teacher can make the error and way of correcting it, clear to the students. Correction in the second case will be counterproductive, unless the teacher can convince the students to change their attitude toward accuracy. Correction in the third case cannot prevent future errors because they do not result from inadequate knowledge. The overload of the cognitive processes probably indicates that the student needs to have more communication practice than correction.According to Spillner (1991), Errors are information. In contrastive linguistics, they are thought to be caused by unconscious transfer of mother tongue structures to the system of the target language and give information about both systems. In the interlanguage hypothesis of second language acquisition, errors are indicative of the different intermediate learning levels and are useful pedagogical feedback. In both cases error analysis is an essential methodological tool for diagnosis and evaluation of the language acquisition process. Errors, too, give information in psychoanalysis (e.g., the Freudian slip), in language universal research, and in other fields of linguistics, such as linguistic change. …

Neuronal spike-train responses in the presence of threshold noise

The variability of neuronal firing has been an intense topic of study for many years. From a modelling perspective it has often been studied in conductance based spiking models with the use of additive or multiplicative noise terms to represent channel fluctuations or the stochastic nature of neurotransmitter release. Here we propose an alternative approach using a simple leaky integrate-and-fire model with a noisy threshold. Initially, we develop a mathematical treatment of the neuronal response to periodic forcing using tools from linear response theory and use this to highlight how a noisy threshold can enhance downstream signal reconstruction. We further develop a more general framework for understanding the responses to large amplitude forcing based on a calculation of first passage times. This is ideally suited to understanding stochastic mode-locking, for which we numerically determine the Arnol'd tongue structure. An examination of data from regularly firing stellate neurons within the ventral cochlear nucleus, responding to sinusoidally amplitude modulated pure tones, shows tongue structures consistent with these predictions and highlights that stochastic, as opposed to deterministic, mode-locking is utilised at the level of the single stellate cell to faithfully encode periodic stimuli.

Dual-degree oral and maxillofacial surgery: evidence-based view of Chilean candidates

Dual-degree oral and maxillofacial surgery: evidence-based view of Chilean candidates

Coupled hard–soft tissue simulation with contact and constraints applied to jaw–tongue–hyoid dynamics

AbstractWe present an open‐source physical simulation system suitable for efficient modeling of anatomical structures composed of both hard and soft tissue components, interconnected by point‐wise attachments, contact, and other constraints. Specific attention is paid to the computational formulation needed for the coupled simulation of rigid and deformable structures, and a constraint‐based mechanism is described for attaching these together. As an application of this system, we then present a novel 3D dynamic model of the jaw–tongue–hyoid complex, consisting of an FEM model of the tongue, rigid jaw, and hyoid structures, point‐to‐point muscle actuators, and constraints for bite contact and the temporomandibular joints. Several simulations are presented showing combined jaw–tongue actions and demonstrating the effects of coupled jaw–tongue–hyoid dynamics. Copyright © 2010 John Wiley & Sons, Ltd.

A Smooth Patch on the Tongue

A smooth, well-demarcated patch without papillae on the posterior portion of the tongue was discovered incidentally while the oropharynx of a 65-year-old woman was being examined. On inquiry, she said that she had been aware of the unusual appearance of her tongue since childhood and that the lesion's size and shape had been stable since that time. She reported no tongue pain, dysphagia, dysarthria, or bleeding. There was no evidence of candidiasis on the tongue or adjacent structures. There was no regional lymphadenopathy, and the patient reported no constitutional symptoms such as fever or weight loss. There was no history . . .

Phytochrome three-dimensional structures and functions

The complete three-dimensional sensory module structures of the Pr ground state of Synechocystis 6803 Cph1 and the unusual Pfr ground state of the bacteriophytochrome PaBphP (PDB codes 2VEA and 3C2W respectively) have now been solved, revealing an asymmetrical dumbbell form made up of a PAS (Period/ARNT/Singleminded)-GAF (cGMP phosphodiesterase/adenylate cyclase/FhlA) bidomain carrying the chromophore and the smaller PHY (phytochrome-specific) domain. The PHY domain is structurally related to the GAF family, but carries an unusual tongue-like structure which contacts the larger lobe to seal the chromophore pocket. In 2VEA, the tongue makes intimate contact with the helical N-terminus; both the N-terminus and the tongue structures are quite different in 3C2W. As expected, the structures reveal ZZZssa and ZZEssa chromophore conformations in 2VEA and 3C2W respectively, associated with tautomeric differences in several nearby tyrosine residues. Two salt bridges on opposite sides of the chromophore, as well as the associations of the C-ring propionates also differ. It is still unclear, however, which of these structural differences are associated with bacteriophytochromes compared with Cph1 and plant-type phytochromes, the unusual 3C2W Pfr ground state functionality compared with the Pr ground state or the Pr compared with Pfr photoisomerism. To access the latter unambiguously, both Pr and Pfr structures of the same molecule are required. New solid-phase NMR data for Cph1 in the Pr, Pfr and freeze-trapped intermediate states reveal unexpected changes in the chromophore during Pfr-->Pr photoconversion. These, together with our efforts to solve the three-dimensional structure of a complete phytochrome molecule are also described.

Turning the corner on intubation: fibrescope-assisted videolaryngoscopy

To the Editor, The Glidescope (Verathon Medical (UK) Ltd., Aston Sandford, United Kingdom) is a videolaryngoscope, which improves the Cormack and Lehane (CL) grade of laryngoscopy due to its 60 viewing orientation. Notwithstanding this ability to ‘‘see around corners’’, it is impossible to intubate the trachea in 4% of patients using the Glidescope , despite a satisfactory glottic view and the use of a preformed stylet or flexible introducer. Reasons for failure include the inability to maneuver the endotracheal tube (ETT) into the glottis or the ETT abutting the anterior portion of the larynx when using the stylet. An intubating fibreoptic bronchoscope (fibrescope) can be dynamically manipulated in multiple directions potentially overcoming the aforementioned limitations. Previous reports of combining a Glidescope and fibrescope were focused either on the Glidescope as an oropharyngeal camera aiding fibreoptic intubation or on a single case performed by one operator with limited detail regarding the technique. We present our experience of fibrescopeassisted videolaryngoscopy (FAV) in both anticipated and unanticipated difficult airways, in multiple patients, and with multiple operators. The FAV technique is performed following induction of general anesthesia and involves two components. First, the Glidescope is inserted to obtain the best possible view of the glottis. Second, the fibrescope (with ETT pre-mounted) is introduced into the pharynx by an assistant until seen on the Glidescope screen. Using the Glidescope image for guidance, the anesthesiologist manipulates the fibrescope to direct it into the larynx and then the trachea (Fig. 1). The ETT is next advanced over the fibrescope, thus securing the airway. The FAV technique has been used successfully in 25 patients, including 12 anticipated and 13 unanticipated difficult airways, where intubation of the trachea was impossible with the Glidescope alone. The cases involved six independent anesthesiologists and one head and neck surgeon. The details of four cases are summarized in Table 1. Since its introduction, there have been no failures using the FAV technique. For CL grades 1 and 2 views, the fibrescope functions as a dynamic laryngeal and tracheal introducer. In patients with CL grades 3 and 4 views, the Glidescope optimizes the position of the tongue and pharyngeal structures facilitating rapid placement of the fibrescope followed by conventional fibreoptic confirmation of tracheal intubation. Fig. 1 Using the Glidescope screen image, the fibrescope tip is placed at the glottic aperture but requires manipulation caudally and posteriorly to enter the trachea

Tumours and tumour-like lesions of the lower face at Korle Bu Teaching Hospital, Ghana – an eight year study

BackgroundThe oro-facial region including the jawbones, the maxilla and mandible and related tissues can be the site of a multitude of neoplastic conditions. These tumours have a predilection for the entire facial region; however, odontogenic tumours tend to affect the mandible more than the maxilla, especially, in West African children. We report results from a retrospective study spanning eight years on the frequency, clinical presentation, sites and character of lower face tumours seen in the main referral hospital in Ghana.Patients and methodsRecords of consecutive patients of all age and sex seen by the first author's team at the Department of Oral and Maxillofacial Surgery, Korle-Bu Teaching Hospital with tumours affecting the lower part of the face from January 1996 to December 2003 were retrieved, coded and entered into a database. The data were then analyzed by age, sex, presenting signs and symptoms, site of lesion, and their histology.ResultsA total of 394 patients with oro-facial swellings were retrieved from the registry out of which 210 had lower face tumour and tumour-like lesions. The complete data set was obtained for 171 patients, comprising 99 (58%) males and 72 (42%) females. The most common clinical presenting features were mandibular facial swelling (63%), intra-oral swelling (55%), pain (41%) and ulceration (29%). The tumours were predominantly found in the right (43%), anterior (19%) and left (18%) aspects of the lower face. The remainder making up 20% were found in the floor of the mouth, tongue and lips. Seventy eight (45.6%) of the patients presented with lesions that were classified as malignant of which 54 (62%) were diagnosed as squamous cell carcinoma (SCC). Sixty-two (36.3%) had benign odontogenic tumours and thirty-one (18.1%) had non-odontogenic tumour-like lesions. Fifty-four (62%) of malignant tumours were squamous cell carcinoma; 58 (93.6%) of the benign odontogenic tumours were classified as ameloblastoma. The mean age at presentation of all lesions was 40.4 years with over 50% of benign lesions in patients aged between 11 and 30 years. Malignant tumours were more commonly detected in patients between 41 and 70 years (63%).ConclusionTumours and tumour-like lesions of the lower face comprising the mandible, tongue and adjacent structures are a diverse group of neoplasm and are seen commonly in practice of Maxillofacial surgery. Both malignant and benign tumours are seen in the Ghanaian population. In the present study, SCC and ameloblastoma were the commonest malignant and benign odontogenic tumours seen respectively; the two representing more than 65% of all tumours.

A new 3D dynamical biomechanical tongue model

A new dynamical biomechanical tongue model is being developed to study speech motor control. In spite of its computational complexity, a 3D representation was chosen in order to account for various contacts between tongue and external structures such as teeth, palate, and vocal tract walls. A fair representation of tongue muscle anatomy is provided, by designing the finite element mesh from the visible human data set (female subject). Model geometry was then matched to a human speaker, so that simulations can be quantitatively compared to experimental MRI data. A set of 11 muscles is modeled, whose role in speech gestures is well established. Each muscle is defined by a set of elements whose elastic properties change with muscle activation. Muscles forces are applied to the tongue model via macrofibers defined within the mesh by muscle specific sets of nodes. These forces are currently specified as step functions. Boundary conditions are set using zero-displacement nodes simulating attachments of tongue on bony structures. The nonlinear mechanical properties of tongue soft tissues are modeled using a hyperelastic material. Three-dimensional tongue deformations generated by each muscle, using FEM software ANSYS for computation, will be presented. Implications for speech motor control will be proposed.

Controllable step motors and rectifiers of magnetic flux quanta using periodic arrays of asymmetric pinning defects

We study the transport of vortices in superconductors with regular arrays of asymmetric pinning wells when applying an alternating electrical current. The asymmetric traps are modelled by the superposition of two interpenetrating square lattices of weak and strong pinning centers with separation smaller than the lattice constant. We show that this system can induce a net rectifying or diode effect for the vortex motion, including collective step-motor-type dynamics, where many vortices move forward a controlled and exact number of pin-lattice spacings at each cycle of the ac driving force. This system exhibits a remarkable net dc response with striking sawtooth-type oscillations. The net dc voltage response ${V}_{\mathrm{dc}}$ of the ac-driven vortices versus both the half period P and the amplitude ${F}_{L}$ of the ``square wave'' ac drive has been detailed in the present work. The influence of the equilibrium thermal noise, the shift between the two pinning sublattices, the degree of translational and orientational disorder, and the size of the simulation system on the ${V}_{\mathrm{dc}}$ response of the vortex motion at ac drive has also been addressed. Devil staircase and Arnold's tongue structures are revealed. We also analytically derive all the key features of our numerical results. This system provides a very controllable stepmotor for the control of collective motion. Our results apply mutatis mutandis to arrays of Josephson junctions, colloidal systems with optical traps, Wigner crystals, and any system with repelling movable objects that can be pinned by a lattice of traps.

Categories of chaos and fractal basin boundaries in forced predator–prey models

Biological communities are affected by perturbations that frequently occur in a more-or-less periodic fashion. In this communication we use the circle map to summarize the dynamics of one such community – the periodically forced Lotka–Volterra predator–prey system. As might be expected, we show that the latter system generates a classic devil's staircase and Arnold tongues, similar to that found from a qualitative analysis of the circle map. The circle map has other subtle features that make it useful for explaining the two qualitatively distinct forms of chaos recently noted in numerical studies of the forced Lotka–Volterra system. In the regions of overlapping tongues, coexisting attractors may be found in the Lotka–Volterra system, including at least one example of three alternative attractors, the separatrices of which are fractal and, in one specific case, Wada. The analysis is extended to a periodically forced tritrophic foodweb model that is chaotic. Interestingly, mode-locking Arnold tongue structures are observed in the model’s phase dynamics even though the foodweb equations are chaotic.

Ultrastructure of the horse tongue: further observations on the lingual integumentary architecture.

This investigation examined primarily epidermal specializations of the adult horse tongue by light, scanning and transmission electron microscopy. Samples were collected from seven regions of the normal tongue of various breeds of horse. The filiform papillae, present on the dorsal and lateral aspects but not the ventral aspect of the tongue, were short, slender and finger-like structures with variable-shaped terminae. The epidermal thickness and height of dermal ridges were reduced on fungiform and vallate papillae, but tissue architecture and keratinocyte ultrastructure of most of the lingual epidermis corresponded to the common mammalian epidermal paradigm. One unique finding was the highly localized clustering of epidermal cells with exceptionally high content of PAS-negative trichohyalin cytoplasmic granules at a location atop the dermal ridges and beneath the base of filiform papillae. These granular cells were immediately subjacent to clusters of clear, non-granulated epidermal cells. It is believed that this integumentary specialization may enhance the structural strength at this localized site of the tissue architecture, in relationship to the mechanical papillae.

A New Class for Modified Mallampati Sign

To the Editor: The Mallampati sign, which is a simple, quick method to predict difficulty with tracheal intubation [1], has gained considerable popularity for airway examination during preanesthetic visits. This sign is dependent on the relative size of the tongue in relation to the pharyngeal structure, but its serious limitations must be evaluated. We report an observation we made during the preoperative airway assessment of a patient in whom we could not ascertain a Mallampati grading. An 80-yr-old, 76-kg woman scheduled for laparoscopic cholecystectomy had a history of repeated oral surgery (five times) for carcinoma of the tongue. During a preanesthetic check-up, we found a complete absence of a tongue, uvula, mandible, and other pharyngeal structures (Figure 1 and Figure 2). Therefore, we were unable to perform Mallampati or modified Mallampati grading [2]; hence, prediction of airway difficulty could not be ascertained. Because the patient refused to undergo the operation, we cannot say with certainty whether this patient had a difficult airway.Figure 1: Front view of patient's face with wide opened mouth showing the absence of pharyngeal structures.Figure 2: Side view of patient's face.Ezri et al. [3] described a clinical situation in which the epiglottis (tip and posterior aspect) could be visualized on mouth opening and protrusion of the tongue and proposed a Mallampati class 0 for this clinical situation. We propose another Mallampati class for cases in which a Mallampati grading cannot be ascertained because of partial or complete absence of the tongue and/or pharyngeal structures. In such an event, preoperative a clinical airway assessment using this grading system is difficult. This situation may be graded as class 5. However, further study is therefore required in relation to difficult intubation in this class. Prabhat K. Sinha, MD, PDCC Sukanya Mitra, MD Satinder Gombar, MD Kanti K. Gombar, MD Department of Anaesthesiology & Intensive Care; Government Medical College; Chandigarh, India

Ultrasonographic analysis of sucking behavior of newborn infants: the driving force of sucking pressure.

The sucking behaviors of 15 low-risk full-term newborns were observed with ultrasonography and a special device directly measuring sucking pressure. In this study, the sequential changes in the movement of a tongue and other intra-oral structures and the sequential changes of the sucking pressure were successfully examined simultaneously. It was indicated that sucking pressure could be generated by sequential changes of an intra-oral volume caused by a peristalsis of the tongue in the sucking behavior.

SEM of the tongue and related vomeronasal structures in Coluber constrictor and Uta stansburiana

The forked tongue in snakes and lizards serves to follow the pheromone trails of both prey and conspecifics. The three phases of the tongue flicking cycle are interrelated with three functional structures involved with the transportation of stimulus particles from the environment to the vomeronasal organ (VNO). (1) The sample phase involves protrusion of the tongue, collection, and transfer of stimulus particles to the anterior processes. (2) A transfer phase in conjunction with the anterior processes serves to facilitate the collection and localization of stimulus particles from the tongue. (3) The delivery phase includes anterior process elevation and the delivery of particles to the VNO. The VNO simultaneously deciphers the chemical concentrations, enabling the animal to follow pheromone trails in relation to the most volatile side, right or left. The morphology of the tongue, anterior processes, and VNO of a previously unevaluated snake and lizard are presented here.Snake species Coluber constrictor and lizard species Uta stansburiana were used in this study. Snakes were collected in Northern Utah and lizards were collected in Southern Utah. All specimens were prepared for scanning electron microscopy using standard techniques.

3-D reconstruction of Ir-192 implant dosimetry for irradiating gingival carcinoma on the mandibular alveolar ridge

A recurrent cancer in the gingiva has been treated by specially fabricating a dental acrylic appliance. This replica of the floor of the mouth, gums, and teeth was constructed with the use of a vinyl polysiloxine impression material. The tumor boundaries were marked in the fabricated appliance with four metal wires to localize the surface and periphery of the tumor. The appliance was molded to hold Ir-192 wires in near contact with the target surface and to allow afterloading. A specially designed lead shield was imbedded onto the dorsal surface of the appliance so as to reduce dose to the tongue and maxillary structures of the mouth. Simulation films and 3-D treatment planning were used to generate isodose distributions and to allow preplanning. The dose calculation algorithm was modified to account for the attenuation in the lead shield represented in three dimensions. The Ir-192 mold was successfully applied for 38 hours in two sessions 1 week apart.