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At least 523 records · Page 29Linked to original sources
PubMed1995

Prevalence of marginal alveolar bone loss in children referred for treatment to the Paediatric Clinic at the School of Dentistry, University of Otago.

Proximal contact loss due to caries may contribute to the appearance of marginal alveolar bone loss (ABL) in the deciduous dentition. Children referred for treatment to the School of Dentistry, University of Otago, usually have special problems related to caries or management, or both, and the aim of the study was to determine the prevalence of marginal ABL in children treated in this clinic, and to compare it with that found in a previous study in a random sample of New Zealand 5-year-olds. Posterior bite-wing radiographs of 187 children, aged 4 to 14 years, were selected for examination. A total of 1,523 sites, from the distal of the deciduous cuspids to the mesial of the deciduous second molar or the first permanent molar if present, were examined. ABL was recorded when there was complete absence of the lamina dura and the distance from the cemento-enamel junction to the crest of the alveolar bone was > 2 mm. ABL was found in 20.8 percent of the children; 31.9 percent of these sites were adjacent to extensive proximal caries; 83.3 percent were in the maxilla, and 95.8 percent were between deciduous teeth. The youngest age at which ABL was found was 5 years. Among the children with ABL, 48.7 percent had ABL in more than one site. Comparison of the prevalence of ABL at age 5 in the present study (19.2 percent) with the one previously reported for a random population (2.1 percent), suggested that, because of the special characteristics of the children attending the University clinic, students are exposed to an exaggerated image of caries and periodontal diseases in children.

Adolescent↗
PubMed1998

[Conditions of the successful outcome of mucogingival surgery during orthodontic treatment].

For the last twenty years the mucogingival surgical technics, particularly displaced flaps, have brought gingival tissue when it is missing improving the periodontic outcome of orthodontic treatment. The displaced flaps are indicated where is a deficient attached gingiva or for uncovering retained cuspids. This state of the art is done both for the surgical and orthodontic care that are necessary as well as for the possible problems and complications after surgery.

Child↗
PubMed1998

Space changes after premature loss of the mandibular primary first molar: a longitudinal study.

The purpose of this study was to evaluate the space changes after premature loss of the primary mandibular first molar. Twenty-one children (12 boys and 9 girls), with premature loss of the primary mandibular first molar, were selected from the children's dental clinic for this study. The age ranged from 5.1 to 7.2 years with an average of 6 years and 11 months. Mandibular study casts were made from alginate impression for each initial examination and a follow-up examination eight months later. Four measurements including D+E (first and second primary molars) space, arch width, arch length and arch perimeter were tested for comparisons between the initial examination and the follow-up examination eight months later. The D+E space of intact primary molars served as a control. The results showed that the D+E space on the extraction side after the follow-up examination eight months later was significantly shorter than the control side (p = 0.025) and less than the initial D+E space (p < 0.001). However, there were no significant differences on arch width, arch length, and arch perimeter between the initial examination and the follow-up examination eight months later (p > 0.05). It is concluded that the space change after the eruption of the first permanent molar in the mandible is mostly distal movement of the primary cuspid during the early stage of premature loss of the primary first molar.

Child↗
PubMed2004

Structure and function of the horn shark (Heterodontus francisci) cranium through ontogeny: development of a hard prey specialist.

The horn sharks (Heterodontidae: Chondrichthyes) represent one of four independent evolutions of durophagy in the cartilaginous fishes. We used high-resolution computed tomography (CT scanning) to visualize and quantify the mineralized tissue of an ontogenetic series of horn sharks. CT scanning of neonatal through adult California horn sharks (Heterodontus francisci) confirmed that this technique is effective for examining mineralized tissue in even small (<10 mm) specimens. The jaw joint is among the first areas to become mineralized and is the most heavily mineralized area in the cranium of a neonatal horn shark. The hyoid is also well mineralized, although the poorly mineralized molariform teeth indicate that the neonatal animal may be a suction feeder on softer prey. The symphysis of the jaws never mineralizes, in sharp contrast to the condition in the hard prey-crushing stingrays. Digitally reslicing the CT scans along the jaws allowed measurement of the second moment of area (Ina). Assuming that the jaws are made of the same material at all ages, Ina is an indicator of the flexural stiffness of the jaws. In all sizes of shark the lower jaws were stiffer than the upper and the stiffness increased in the area of the molariform teeth. The central region of the jaws, where the rami meet, support cuspidate grasping teeth and has the lowest Ina. The spotted eagle ray (Aetobatus narinari), a hard prey-crushing stingray, shows a different pattern of flexural stiffness, with the peak at the central part of the jaws where the prey is reduced between flattened tooth plates. Although the eagle ray jaws have a higher Ina than the horn shark, they are also far more heavily mineralized. When the relative amounts of mineralization are taken into account, horn sharks do better with what mineral they have than does the eagle ray. With a tight jaw joint and loose mandibular symphysis, as well as nearly opposite patterns of stiffness in the jaws, it is clear that two of the clades of hard prey specialists use very different methods for cracking the hard prey problem.

Animals↗
PubMed2004

Mechanical functions of setae from the mouth apparatus of seven species of decapod crustaceans.

The mouthpart setae of seven species of decapods were examined with macro-video recordings and scanning electron microscopy. The general mechanical (nonsensory) functions of the different mouthparts are described and an account of their setation is given. This offers the possibility to determine the mechanical functions of the different types of setae. Pappose setae do not participate in food handling but in general make setal barriers. Plumose setae likewise do not contact food objects but assist in current generation. Papposerrate setae are rare but they were seen to assist in pushing food particles into the mouth. Serrulate setae are very common and mainly participate in gentle food handling and grooming. Serrate setae are used for more rough food manipulation and grooming. The roughest shredding, tearing, and manipulation of prey items are handled by the cuspidate setae. Simple setae seem to be divided into two populations with very different functions. On the maxillipeds of Panulirus argus they are used for shredding, tearing, and holding the food objects, but on the basis of maxilla 2 of three other species they appear to have very little mechanical influence and only when handling small prey items. The functional scheme seems to be consistent within the Decapoda.

Animals↗
PubMed2006

Ultrastructure and functional organization of mouthpart sensory setae of the spiny lobster Panulirus argus: new features of putative mechanoreceptors.

In comparison with other decapods, the Caribbean spiny lobster Panulirus argus has little diversity in the external morphology of the setae on the mouth apparatus. In mouthpart areas that frequently touch food items only two types of setae can be distinguished: simple setae and cuspidate setae. Simple setae are by far more numerous. The ultrastructural data presented here show that both types of seta are bimodal, in that they both contain mechano- and chemosensory cells as indicated by morphological features. The morphological features divide the sensory cells into three types: type 1, which has a mechanosensory appearance; type 2, which has a chemosensory appearance; and type 3, which is believed to be a mechanoreceptor due to desmosomal connections to a scolopale. All three cell types were found in all examined setae. In an earlier study the simple setae were found to contain two types of mechanosensors: bend-sensitive cells and displacement-sensitive cells. The morphological arrangement of the outer dendritic segment described in the present study cannot explain this division. Instead, it is suggested that the difference in sensitivity is caused by a differential arrangement of their stretch-sensitive ion channels. This hypothesis also provides an explanation for the earlier observation that only bend cells respond to changes in osmolarity.

Animals↗
PubMed1999

Parasitism increases offspring size in a damselfly: experimental evidence for parasite-mediated maternal effects.

The effects of parasites on host fitness and the fitness effects of maternal effects are widely discussed. In this study, I conducted an experiment linking both aspects. I manipulated the ectoparasite load (Acari: Arrenurus cuspidator) of damselflies, Coenagrion puella, and found that larvae from mothers with high parasite loads were larger (assessed by head width) than larvae from mothers with low parasite loads. Furthermore, there was a negative correlation between the number of eggs laid and parasite load. Parasitized mothers thus seemed to have fewer, but probably better, offspring. The ecological significance of these parasite-mediated maternal effects remains to be tested. However, size-dependent cannibalism almost certainly has important consequences for population dynamics. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed2005

Robust visualization of the dental occlusion by a double scan procedure.

A detailed visualization of the dental occlusion in 3D image-based planning environments for oral and maxillofacial planning is important. With CT imaging however, this occlusion is often deteriorated by streak artifacts caused by amalgam fillings. Moreover, more detailed surface information at the level of the dental cuspids is often desired. In this paper, a double scan technique is introduced to image the dental occlusion by means of a newly designed 3D splint. The patient wears this splint between the upper and lower teeth during CT-scan. In a second step, the splint is positioned between the plaster casts of the upper and lower jaw, and this setup is scanned. Based on markers in the 3D splint, both data sets are fused and a combined visualization is possible. The accuracy, robustness and applicability in clinical routine is shown. This technology enables meticulous 3D cephalometric analysis, detailed maxillofacial planning and opens possibilities towards intraoperative support.

Cadaver↗
PubMed1986

Morphology of a GHRH producing pancreatic islet cell tumour causing acromegaly.

A 54 year old woman suffered from acromegaly due to a pancreatic islet cell tumour producing GHRH. The tumour was demonstrated on CT scan. The diagnosis was established from elevated plasma levels of GHRH, GH and prolactin, and by the lack of signs of a pituitary adenoma in trans-sphenoidal surgery. Acromegaly was cured by tumour removal. Light microscopically, the tumour showed a medullary and microlobular pattern. The cells were large and often cuspidal. Small granules were found in semi-thin sections. Small aggregations of amyloid fibres were seen, mostly around capillaries. Immunocytochemistry revealed GHRH, NSE, neurotensin, serotonin, VIP and PP. S 100 was positive only in nerve fibres. Staining for GH, ACTH, calcitonin, alpha-HCG, beta-HCG, insulin, glucagon, gastrin, substance P, bombesin and somatostatin was negative. Ultrastructure showed oval partly lobulated nuclei with small nucleoli, moderate amounts of rough endoplasmic reticulum, many free ribosomes, some large Golgi fields and small numbers of secretory granules measuring 150 nm or, in a few cells, 650 nm. Only 4 other cases of pancreatic endocrine tumours causing acromegaly by ectopic GHRH secretion are described in the literature and these were similar to our case in many respects.

Acromegaly↗
PubMed1998

The force module for the bending art system. Preliminary results.

The force module for the bending art system (BAS) is used to calculate the initial forces and moments expected to act on a tooth after changing arch wires. The present study analyses the accuracy of the force module on the basis of 10 patients treated with the BAS (with an average observation period of 10 months). An average of 6 arch wires (0.16" x 0.016" steel) were used on each jaw. The approximate pressure in the periodontium was determined and statistically evaluated from the force module readings. The resulting average pressure values for the molars ranged between 0.26 N/cm2 and 0.54 N/cm2. The value in the area of the incisors, cuspids and bicuspids ranged between 1.03 N/cm2 and 2.83 N/cm2. Maximum pressure was 8.02 N/cm2. The results are discussed from a clinical point of view on a case-to-case basis. They are plausible in and for themselves. The more severe the initial state of misalignment, the higher the pressure values. These forces can be reduced by increasing the number of arch wires or by altering the form of the archwire correspondingly. The computer-generated values should be confirmed by taking a direct measurement on the tooth. The force module is just the first step in providing a reproducible estimation of the forces acting on a tooth. Even if the calculated absolute values should still be judged with reservation, they are nevertheless suitable for providing a comparative evaluation of various treatment concepts with reference to the forces acting on the periodontium and can serve clinicians as a rapidly available decision-making aid.

Adolescent↗
PubMed1987

Ultrastructure of degenerative changes following ricin application to feline dental pulps.

The ultrastructure of degenerative changes within the ipsilateral trigeminal ganglion, and partes caudalis and interpolaris of the spinal trigeminal nucleus in the cat is described following the application of the potent toxin ricin to the tooth pulps of unilateral maxillary and mandibular posterior teeth, including the cuspids. Survival times ranged from 6 to 10 days. Typical changes identified within the ipsilateral trigeminal ganglion included myelin fragmentation and 'compartmentalization' of the axoplasm of medium-sized myelinated axons, while small myelinated and unmyelinated axons underwent a more variable response ranging from electron-lucent to electron-dense changes. The affected cell body was characterized by the presence of swollen, electron-lucent mitochondria, a reduction of cytoplasmic ribosomes and a filamentous hyperplasia. Other changes often included an eccentric nucleus and satellite cell proliferation. Degenerative changes often occurred in isolated elements surrounded by normal profiles, suggesting specificity of ricin within the trigeminal ganglion. Changes within brainstem axons showed both an electron-dense and a lucent, fragmenting type of axonal alteration. Terminal changes ranged from electron-dense to lucent and also included filamentous hyperplasia and 'hyperglycogenesis'. The altered axonal knobs contained round synaptic vesicles that were presynaptic to dendritic profiles and postsynaptic to terminals containing flattened synaptic vesicles. The above brainstem alterations were identified specifically in the following areas: ventrolateral, medial and dorsomedial pars interpolaris; the ventrolateral and mid-dorsal to dorsomedial areas of the marginalis and outer substantia gelatinosa layers of pars caudalis; and in ventral pockets corresponding to lamina V of the medullary dorsal horn. Dense alterations within terminals containing flattened synaptic vesicles that are typically presynaptic to primary afferents in these areas were rare findings, but along with vacuolization of dendritic profiles suggest a trans-synaptic effect possibly due to the exocytosis of ricin. The results are discussed in relation to different reports of dental projections and with regards to patterns of transganglionic degeneration.

Animals↗
PubMed2004

Applications for direct composite restorations in orthodontics.

BACKGROUND AND AIM: Besides prosthetic and indirect, laboratory-produced restorations, the focus of dental therapy is increasingly on restorative measures and direct restorations as minimally invasive treatment concepts. Thus, the use of direct composite restorations with modern restorative materials for the shaping and recontouring of teeth in combination with orthodontic treatment offers a diversified, extensive sphere of application. The aim of the study was to demonstrate applications for direct composite restorations with reference to selected cases. MATERIAL AND METHODS: The composites used were hybrid composites, which offer increased abrasion resistance and color stability and are applied incrementally. Special attention was paid to the shape, color and structure of the tooth. CASE REPORTS: The case reports present patients in whom relatively narrow or peg-shaped teeth were built up with composite to correct various tooth size discrepancies or cuspids were recontoured by means of direct composite restorations following orthodontic space closure in cases with missing lateral incisors. Similarly, space closure was achieved using orthodontically repositioned lateral incisors recontoured to resemble central incisors after traumatic loss of upper central incisors. Finally, direct composite restorations were used for retention following completion of orthodontic treatment. CONCLUSIONS: Observations over recent years confirm the stability of composites in both form and color, as well as their ability to maintain gingival health. Our case reports demonstrate that, subject to a corresponding indication, recontouring single teeth using direct composite restorations can optimize orthodontic treatment results.

Acrylic Resins↗
PubMed2006

Dental microwear in relation to changes in the direction of mastication during the evolution of Myodonta (Rodentia, Mammalia).

Observations of dental microwear are used to analyse the correlation between changes in molar tooth crown morphology and the direction of masticatory movement during the evolution of Myodonta (Rodentia, Mammalia). The studied sample includes 36 specimens representing both superfamilies of Myodonta (Muroidea and Dipodoidea) spanning 16 dipodoid and 9 muroid species. Microscopic scratches on occlusal surfaces resulting from contact between opposite teeth during mastication are analysed. Using these features, we determine the direction of masticatory movements. Microwear patterns display diverse orientations among Dipodoidea: oblique in Sicistinae, Euchoreutinae and Zapodinae, propalinal in Dipodinae and intermediary in Allactaginae. Similarly, Muroidea exhibit the following orientations: oblique in Cricetinae and propalinal in Arvicolinae, Cricetomyinae, Gerbillinae and Murinae. These various chewing types illustrate different evolutionary grades within the superfamilies. Acquisition of the antero-posterior masticatory movement in Dipodoidea is related to flattening of the molar occlusal surface. However, in some muroid subfamilies, this direction of mastication is associated with low-crowned and cuspidate molars (Cricetomyinae, Murinae).

Animals↗
PubMed1999

[Migration of a retained premolar into the processus muscularis of the mandible].

Migration of an impacted mandibular premolar is a rare finding, whereas dystopia of lower jaw cuspids is described much more often in the literature. We present a patient in whom radiographic studies show the migration of a mandibular premolar to the muscular process over a period of 14 years. Most of the tooth migration along the vertical portion of the mandibula into the processus muscularis took place after the root development had ended. Neither radiological nor clinical examination revealed the stimulus which changed the path and the direction of the impacted tooth.

Adult↗
PubMed1975

Direct bonding on impacted teeth.

In eighteen patients twenty-three impacted teeth were surgically exposed and provided with Cuspid-Pull Brackets by the direct-bonding technique. Light orthodontic traction was applied after 10 minutes. Only three brackets were lost during the experiment. The experiment showed that sufficient bonding could be established on impacted teeth without pumicing the tooth surface and that phosphoric acid in minimal amounts causes no harm to the adjacent tissues but assists in preventing bleeding from the surrounding tissues. This made it possible to obtain the necessary dryness of the exposed tooth surface. The reasons for bond failure are discussed.

Adolescent↗
PubMed1991

Hypertrophy of nodules of Arantius and aortic insufficiency: pathophysiology and repair.

Aortic insufficiency (AI) due to fibrosis and thickening of the nodules of Arantius in the otherwise normal aortic valve was found in 11 adults (age range, 41 to 65 years) between 1976 and 1988. Nine had concomitant mitral stenosis; 2 had coronary artery disease. In 6 patients AI was graded 3+ or greater; in 5 it was less than 3+. Correction of AI and restoration of cuspid flexibility and apposition by shaving the hypertrophied nodules was accomplished in all, with postrepair AI graded as 1+ or less. There was one hospital death, a patient who had prior mitral operation. Mean follow-up was 68 +/- 56 months. Only 1 patient had late (6 years) recurrent serious (3+) AI. Nine continued to have 1+ or less AI, based on echocardiography or catheterization (n = 6) or on physical examination performed at a mean of 74 months. We conclude that thickening of the nodules of Arantius may cause AI. Long-term correction can be accomplished by sculpturing of the involved cusps.

Adult↗
PubMed1994

Lunular hypertrophy and aortic valve disease.

Cuspid malcoaptation secondary to abnormal hypertrophy in combination with stiffening involving the line of apposition (lunular hypertrophy) has not been recognized as a cause of aortic valve dysfunction. This entity was found in 50 adults (mean age, 62 years). Thirty-three had pure aortic valve insufficiency (> or = 3+, n = 13; < 3+, n = 20), 13 had mixed aortic valve insufficiency and stenosis (> or = 3+, n = 2; < 3+, n = 11), and 4 had pure aortic valve stenosis. Forty-one had a history of rheumatic heart disease and advanced mitral valve disease, and 7 had coronary artery disease. All underwent shaving of the hypertrophic protuberances, which in 26 patients constituted the entire aortic valve repair. In the remaining 24 patients, aortic valve repair included one or more additional procedures; there were 15 commissurotomies, 12 debridements of calcium deposits from the base of the cusps, and 5 cusp resuspensions. Concomitant mitral valve repair was performed in 26 patients, mitral valve replacement in 15, tricuspid valve repair in 11, coronary artery bypass grafting in 7, and repair of an ascending aortic aneurysm in 2. In 2 patients, the attempt to repair the aortic valve was unsuccessful, necessitating valve replacement. There were 5 operative deaths (10%), but none were related to aortic valve repair. Forty-three patients entered follow-up (mean, 56 +/- 57 months). Three patients (7%) suffered late recurrent aortic valve insufficiency (at 6, 48, and 72 months). The remaining 40 patients (93%) had trivial or no recurrent aortic valve dysfunction. The 6-year actuarial freedom from aortic valve-related problems was 92%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗