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At least 811 records · Page 45Linked to original sources
PubMed2004

[Research on the effect of root canal seal achieved by irradiation of Er, Cr:YSGG laser].

PURPOSE: To evaluate the effect of root canal seal achieved by routine root canal preparation and irradiation of Er, Cr:YSGG laser in root canal therapy. METHODS: One hundred and five freshly single-rooted extracted human teeth were selected for the study, which were randomly divided into seven groups of fifteen each. The anatomic crowns were removed at the cementoenamel junction and the remaining roots were prepared endodontically with conventional methods. Then they were treated with Er, Cr:YSGG laser in different parameters and patterns. The effect of root canal seal achieved by Er, Cr:YSGG laser was evaluated with microleakage measurements. Newman-Keuls test and one-way analysis of variance were used to determine the statistical differences between various groups. A value of P<0.05 was considered to be significant. RESULTS: The amount of dye penetration from an apical stop with irradiation of Er, Cr:YSGG laser was significantly lower (P<0.05) except 3W laser without water flow, and in 1W Er, Cr:YSGG laser without water flow, the amount of apical dye penetration was significantly decreased (P<0.01). CONCLUSIONS: The utilizing of Er, Cr:YSGG laser in small parameters prior to root canal filling could promote the effect of apical seal. Based on our results, it appeared that the seal effect of 1W Er, Cr:YSGG laser without water flow was superior to the effects of others.

Dental Leakage↗
PubMed2005

[Retrograde obturation with MTA Cement and Super-EBA after apicoectomy. Sealing ability of MTA and Super-EBA in dye penetration tests].

The present in vitro study investigated the sealing of retrograde fillings compounded of two different cements in consideration of cracking after root-end preparation of resected dental roots using diamond-coated ultrasonic retrotips. Root-end cavities were prepared in 32 resected roots using diamond-coated ultrasonic retrotips. The samples were divided into two groups. The first group was filled using zinc-oxide cement (Super-EBA-Cement), the second with mineral-trioxide-aggregate (Pro Root MTA). After resection, root-end preparation and retrograde filling, the samples were analysed using macro-zoom photography and scanning electron microscopy. The sealing quality of the filling materials was detected through dye penetration test. The average degree of penetration of the samples filled with Super-EBA-Cement was 2.19 and of the samples filled with Pro Root MTA 0.44 respectively. Accordingly the sealing of Pro Root MTA in vitro is superior to the sealing of Super-EBA-Cement. Retrograde conditioning of resected roots with ultrasonic retrotips represents an efficient and sparing alternative to conventional root-end preparation techniques.

Adult↗
PubMedDate not supplied

In vitro evaluation of the implant-abutment bacterial seal: the locking taper system.

PURPOSE: To test in vitro whether the seal provided by the locking taper used in the implant-abutment connection was capable of preventing the invasion of oral microorganisms. MATERIALS AND METHODS: Twenty-five wide-body implants (5 x 11 mm) and 25 abutments were divided into 2 groups for a 2-phase experiment. The first phase tested the ability of the seal to shield the implant well from outside bacteria; the second phase tested the ability of the seal to prevent bacteria present in the implant well from seeping out. For phase 1, 10 implant-abutment units were immersed in a bacterial broth for 24 hours. The abutments were then separated from the implants and bacterial presence was evaluated using scanning electron microscopy. In phase 2, the tested abutments were inoculated with a droplet of soft agar bacterial gel and assembled with the implant. These units were incubated in a sterile nutrient broth for 72 hours, sampled, and plated to assess bacterial presence. RESULTS: In phase 1, no bacteria were detected in any of the implant wells. In phase 2, no bacteria were detected in the nutrient broth or on the agar plates at 72 hours. DISCUSSION: In implants where a microgap is present, microbial leakage could lead to inflammation and bone loss; thus, it is important to minimize bacterial presence in and around the the implant-abutment junction. CONCLUSION: The seal provided by the locking taper design has been demonstrated to be hermetic with regard to bacterial invasion in vitro.

Colony Count, Microbial↗
PubMed2006

Bacterial colonisation of interior implant threads with and without sealing.

Premature loss of dental implants is due, apart from mechanical factors, to germrelated inflammation. Gaps and hollow spaces within the implant system, for example the gap between implant and abutment in the two-part implant system, may provide a bacterial reservoir causing or maintaining inflammation. The bacterial spectrum involved is similar to that found in periodontitis. This in vitro study aimed to scrutinise the capability of Porphyromonas gingivalis (DSM 20709), the bacterium blamed for inducing peri-implantitis, to pass the implant/abutment gap in titanium implant systems used for orthodontic anchorage and to remain vital in the interior. Additionally, the in vitro effectiveness of gutta percha for gap sealing was examined. Twelve titanium implants (Straumann, diameter: 3.3 mm, length 5.5 mm) were provided with abutments at a defined torque (20 Ncm), six of which were sealed with gutta percha before screwing in the abutment. Subsequently the implants were placed in a nutrient solution (thioglycolate boullion with haemin-menadione solution) that contained Porphyromonas gingivalis. Microbiological specimens were sampled from the implant interiors after 24 and 72 hours and analysed using culture methods. There was evidence that penetration of the periodontal pathogen Porphyromonas gingivalis to the implant interior may occur as early as after 24 hours. Microbes were also detected in the interior of implants sealed with gutta percha. The abutment/implant interface in vitro provides a microbiological leakage for the prospective peri-implantitis-inducing bacterium Porphyromonas gingivalis. Survival of the bacterium is possible in the interior, so that development of a bacterial reservoir is assumed. This in vitro trial produced no evidence that sealing with gutta percha is an effective means to prevent secondary bacterial colonisation in the implant interior.

Colony Count, Microbial↗
PubMed2006

The cleft seal for bottle-feeding--A report on case studies.

Clefting of the lip and palate is the most frequent craniofacial malformation that occurs in newborn babies. The greatest immediate challenge facing a neonate with a cleft is to take nourishment. In developing countries and particularly in rural areas, palatal obturators and other aids that can assist in feeding are not easily available or accessible. The aim of this study was to develop, evaluate and report on the cleft seal, a simple and inexpensive device that is used with a feeding bottle to promote nourishment of a neonate with a cleft palate. The cleft seal is made of either silicone or thermoform plastic and consists of a spoon-like projection attached to a circular washer. The latter fits snugly between the teat base and collar of the feeding bottle, while the spoon-like projection forms a canopy over the teat and separates the nasal cavity from the mouth during feeding. Closure of the cleft emulates the natural feeding process and favours normal orofacial development. Results from this study indicate that there is an increase in nutritional intake over a shorter feeding time when using the cleft seal. Parents also report an absence of nasal regurgitation. The greatest advantage of the cleft seal lies in its negligible cost and ease of use, which can enable distribution and application in remote neonatal centres, where nursing and parental care givers are often at a loss as to what to do when faced with a newborn with a cleft palate.

Bottle Feeding↗
PubMedDate not supplied

[The effect of postpalatal seal on the retention of a full upper denture].

The retention of a full upper denture is seriously affected by the border seal and especially by a correct and strong postpalatal seal, which occurred before the receiving of the final impression. In this article we describe the effects of a correct and strong pospalatal seal on the function of a full upper denture, as well as the procedure that should be followed in order to achieve a correct posterior palatal seal.

Denture Design↗
PubMed1989

The effect of sealing white spot lesions on lesion progression in vitro.

The resistance of white spot lesions to acid demineralization when etched with phosphoric acid and sealed with a resin material was studied. Artificially created white spot lesions were sealed and re-exposed to an artificial caries medium along with unprotected white spot lesions. Examination with polarized light microscopy revealed continued progression of the unprotected white spot lesions, whereas no lesion progression was evident under the resin sealant. New lesions formed on unprotected sound enamel adjacent to the margin of the resin sealant over sound enamel tangent to the white spot lesions. The sealed sound enamel adjacent to the white spot lesions did not undergo demineralization indicating protection by the resin tags. Sealing white spot lesions following etching with a 37% phosphoric acid may be beneficial in inhibiting lesion progression.

Acid Etching, Dental↗
PubMed1989

[Effect of dowel space preparation on the integrity of the apical seal].

Fifty-six single-rooted maxiller teeth obturated with amalgam, N2 and AH26 were tested in vitro to determine if dowel space preparation had an effect on apical seal. Dye penetration was evaluated using 210 UV Spectrophotometer and it was observed that the use of AH26 with or without gutta-percha to seal the root was the most suitable technique on apical seal and dowel space preparation did not influence the sealing ability of it.

Crowns↗
PubMedDate not supplied

Cariostatic and ultraconservative sealed restorations: nine-year results among children and adults.

The objective of this clinical study was to evaluate the long-term efficacy of placing sealed posterior composite restorations for arresting active caries. The tooth preparation for this bonded and sealed restoration was limited to placing a bevel in the enamel only, without the removal of the carious lesion. The radiographic and clinical performance of these ultraconservative sealed composite restorations placed over caries (CompS/C) was compared over a period of nine years with: 1) ultraconservative, localized sealed amalgam (AGS) restorations with no extension for prevention, and 2) traditional, unsealed amalgam restorations (AGU) with the usual extension for prevention outline form. Sealant retention with > 50 percent to 100 percent of the margins occurred in 64 percent of CompS/C and 82.5 percent of AGS restorations. After nine years the cumulative failure rates were 16 percent for CompS/C, 2.5 percent for AGS, and 17.1 percent for AGU restorations. Thus, the clinical performance of CompS/C restorations was slightly superior to that of the traditional AGU restorations. The AGS restorations were definitely superior to the traditional AGU restorations and to the CompS/C restorations in both children and adults alike. Complete sealant retention over CompS/C and AGS restorations was equivalent between children and adults (P = 0.14 and 0.74, respectively). A higher percentage of open margins in CompS/C restorations was seen, however, in children (17.4 percent) than adults (1.94 percent). This study has shown that Class I caries can be arrested by the CompS/C restoration.

Adolescent↗
PubMed1995

[Corneoscleral wound healing after self-sealing cataract surgery--2. Cellular proliferation].

We investigated histologically wound healing after self-sealing cataract surgery, focusing on cell proliferation. A scleral pocket and internal corneal flap were made according to Ernest's method in rabbit eyes on one side. After phacoemulcification procedure was performed, balanced salt solution (BSS plus) was injected to self-seal the wound (self-sealing group). After the same procedures were performed in the contralateral eyes, a horizontal 9.0 Nylon suture was placed in the wound (suture group). On various days after operation, the eyes were analyzed by corneal topography and enucleated. The corneo-scleral tissues were labelled with 3H-thymidine (10 microCi/ml) at 37 degrees C for 4 hr in Dulbecco's minimum essential medium, fixed with 4% paraformaldehyde and subjected to autoradiography. On the first day after operation, the scleral stromal fibroblasts at the scleral side and keratocytes at the corneal side incorporated 3H-thymidine. The 3H-thymidine uptake ratio was the highest on the first day and then gradually decreased. On the seventh day after operation, this incidence was higher in the suture group than in the self-sealing group, possibly due to the influence of the suture. We suggest that the difference in cellular proliferation during wound healing between the two groups might affect late postoperative astigmatism.

Animals↗
PubMed1996

[Pro and contra fissure sealing].

Whereas in Germany fissure sealing has just become a routine treatment in caries prevention, scientists from Sweden and Switzerland proclaim this procedure as economically ineffective. This may result from a low caries prevalence in these countries, which means that only few fissures tend to turn into carious lesions without protection by a fissure sealing. Caries prevalence in Germany is still at a higher level. Thus fissure sealing can be considered cost effective. Besides this, from an ethical viewpoint, the protection and reestablishment of health should never be seen only as an economical issue. That is why fissure sealing is highly recommended as a caries preventive procedure.

Adolescent↗
PubMed1977

Fine structure of seminiferous tubules in antarctic seals.

The fine structure of seminiferous tubules from 5 crabeater, 2 leopard and 2 Ross seals showed that during the nonbreeding season the tubules were essentially similar in possessing spermatogenic and Sertoli cells. However, the tubules of leopard and Ross seals had more primary and secondary spermatocytes and spermatids than the crabeater seals. In general, the tubules were devoid of spermatozoa. The spermatids showed stages of maturation such as Golgi phase of acrosome formation, acrosomal cap formation and condensation of nuclei. Some spermatids degenerated in tubules. Both maturing and degenerating spermatids were closely associated with Sertoli cells. Junctional complexes with plaques of filaments were observed between Sertoli cells and the spermatogenic cells. Sertoli cells, irregular and polygonal, contained highly convoluted nuclei, strands of rough endoplasmic reticulum, smooth endoplasmic reticulum, Golgi complexes, small mitochondria, variable amounts of lipid droplets, lysosomes, lipofuscin granules and highly plicated plasma membranes. In brief, the spermatogenic activity had practically ceased in the testes and the animals probably secreted low levels of testosterone during the nonbreeding season.

Animals↗
PubMed1999

Evidence of saxitoxin derivatives as causative agents in the 1997 mass mortality of monk seals in the Cape Blanc Peninsula.

Monk seals in Cape Blanc (Western Sahara coast) suffered a mass mortality during May-July 1997 which was attributed to a morbillivirus. High performance liquid chromatography (HPLC) analysis on tissues of seals killed during the outbreak and on related fauna showed peaks with retention times coincident with those of some saxitoxin derivatives but their identity was not proved. Here we present results of further HPLC analyses that unambiguously prove the identity of these toxins by mass spectrometry (MS), supporting the hypothesis that this mortality of monk seals was caused by biotoxins rather than by a morbillivirus.

Africa↗
PubMed1976

Functional anatomy of the hands of fur seals and sea lions.

Dissections and manipulations of the hands of 14 specimens of four genera of fur seals and sea lions and of generalized fissiped carnivores were used to identify the structural modifications involved in formation of the expanded forelimb paddles characteristic of these pinnipeds. The morphological peculiarities were then correlated with differences in locomotor function, both on land and in the water, on the basis of previously published data, for the purpose of identifying modifications of structure and function which have adaptive vale. Structural differences found in the manus of fur seals and sea lions include: (1) reduction in size of the ulnar side of the carpus and a radial shift in the length-order of the digits, (2) development of musculature in the antebrachial fascia which attaches to the caudal margin of the flipper, (3) orientation of the radial side of the manus dorsal and radial to the rest of the hand, (4) increased range of possible midcarpal movement and in deviational mobility at the first and fifth digits, (5) attachment of forearm musculature onto radial digits and (6) well-developed hypothenar muscles and absence of thenar muscles. Modifications in hand structure are viewed as providing a morphological basis for employment of the hand to advantage during aquatic locomotion while maintaining thrust-producing and potentially energy-conserving capacities during movement on land. As such these differences in structure and function are viewed as adaptations to locomotion in the water and on land which are extensions of locomotor adaptations attributed to modifications of forelimb structure and function associated with the generation of massive aquatic locomotor thrust. The adaptive value of such modifications is interpreted as allowing fur seals and sea lions to swim with speed and thereby capture elusive fast-swimming prey while maintaining a level of terrestrial locomotor ability compatible with their amphibious mode of life.

Animals↗
PubMed2006

Microstructure and innervation of the mystacial vibrissal follicle-sinus complex in bearded seals, Erignathus barbatus (Pinnipedia: Phocidae).

Vibrissal follicle-sinus complexes (F-SCs) are sensory receptors of the mammalian integument system. They are best developed within Pinnipedia. The objective of this study was to investigate the F-SCs of bearded seals (Erignathus barbatus) for benthic foraging adaptations. Bearded seals possessed approximately 244 mystacial F-SCs. In this species, F-SCs consisted of an outer dermal capsule (DC) surrounding a blood sinus system [upper cavernous sinus (UCS), ring sinus (RS), and lower cavernous sinus (LCS)] and concentric rings of epidermal tissue. The UCS comprised up to 62% of the F-SC length and may function as thermal protection for mechanoreceptors. A large asymmetrical ringwulst was located in the RS. A deep vibrissal nerve penetrated the DC at its base and terminated on mechanoreceptors in the epidermal tissues of the LCS and RS. The mean number of myelinated axons per F-SC was 1,314 (range, 811-1,650) and was among the highest number of axons per F-SC reported to date. An estimated mean number of 320,616 myelinated axons innervate the entire mystacial vibrissal array. Merkel-Neurite complexes (MNCs) and small simple laminated corpuscles were found in the region of the LCS. Myelinated axons also terminated on MNCs and lanceolate endings apical to the ringwulst. The number of F-SCs, their geometry in the mystacial region, the number of myelinated axons per F-SC, and the distribution of mechanoreceptors support the premise that pinniped vibrissae are sensitive active-touch receptor systems, and that structural differences in bearded seals, relative to other phocids, may be adaptations for benthic foraging.

Animals↗
PubMed1975

A gross and microscopic study of the respiratory anatomy of the Antarctic Weddell seal, Leptonychotes weddelli.

Four species of Phocidae, or true seals, inhabit the waters surrounding the Antarctic continent. These animals are thought to have different diving capabilities. The Weddell seal, Leptonychotes weddelli, is known to be capable of attaining depths up to 600 meters. The respiratiory system of the Weddell seal shows the usual adaptations to an aquatic environment characteristic of other marine. These include lungs that undergo compression acollapse at depths greater than 70 meters; hyaline cartilage in the tracheo-bronchial tree as far as the terminal bronchioles; and large amounts of smooth muscle surrounding the distal-most bronchioles. The collapsible lungs provide a mechanism by which air is forced from the alveoli adjacent to the pulmonary capillary beds thereby preventing the absorption of nitrogen gas into the bloodsteam. The presence of hyaline cartilage throughout most of the tracheo-bronchial tree increases the effective dead air space that accommodates most of the air forced from the collapsed lungs. The smooth muscle surrounding the respiratory bronchioles prevents their collapse while under the pressures of a deep dive. Collapse of the respiratory bronchioles not supported by cartilage would trap air in the lung alveoli during a dive. In addition, large- sac-like "diverticulae" are found in the submucosa throughout the tracheo-bronchial tree. These diverticulae, which open directly into the lumen of the tree, appear to be modified glands whose cells, in most cases, do not appear to be specialized for secretory function. They are most numerous in the more distal bronchi and terminal bronchioles where they are situated on both the luminal and adventitial sides of the hyaline cartilage supporting the walls of the air passages. Diverticulae are not found in the respiratory bronchioles or in the respiratory portion of the lungs.

Acclimatization↗
PubMed1998

Modelling the spread of phocine distemper virus among harbour seals.

Data presented in earlier publications on the 1988 epizootic among seals in North West Europe show a pattern that is somewhat inconsistent with the predictions of the standard mathematical model of epidemics. We argue that for animals living in herds or colonies, such as seals, the mutual contact behaviour is such that models for the transmission of infectious diseases should be applied with special care for the distinction between numbers and densities. This is demonstrated by using a mechanistic description of the contacts among seals, which leads to a slightly different formulation of the model. Results of the analysis of this formulation are more in line with the data. The model introduced here can be applied to epidemics among all kinds of animals living in herds and in fact to any species with constant local density, independent of the total population size (i.e., occupying a variable area). Application of the traditional formulation, using different parameters for herds of different sizes, will give equally good results for non-lethal diseases. However, especially for diseases with a low R0 and high death rates, such as the phocine distemper virus (PDV) disease, the two model formulations give quite different results. Further analysis of the model is performed to determine the most important factors influencing such an epidemic. The survival of infected animals turns out to have a disproportionately great influence on the intensity of the epidemic. Therefore in the case of the PDV epizootic we conclude that marine pollution may not only have contributed to the high death rates, but, if so, it has intensified the epizootic as well.

Animals↗
PubMed1979

Structure of the testis in neonate and adult harp seals, Pagophilus groenlandicus.

The structure of the seminiferous tubules in neonate harp seals, Pagophilus groenlandicus, was essentially similar in one-, five- and ten-day old animals. The tubules were small in diameter, devoid of lumina and contained predominantly supportive cells. The interstitial cells in the neonates were large, numerous and highly vacuolated. They became smaller and appeared less active in the ten-day old animals compared with the one-day old seals, although they were still considerably more numerous and vacuolated than in testes taken from adult harp seals.

Aging↗