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At least 955 records · Page 53Linked to original sources

PubMed2000

Regional anesthesia of the infraorbital and inferior alveolar nerves during noninvasive tooth pulp stimulation in halothane-anesthetized cats.

OBJECTIVE: To determine whether anesthesia of the infraorbital and inferior alveolar nerves abolishes reflex-evoked muscle action potentials (REMP) during tooth-pulp stimulation in halothane-anesthetized cats. ANIMALS: 8 healthy adult cats. PROCEDURE: In halothane-anesthetized cats, an anodal electrode was attached to the tooth to be stimulated and a platinum needle cathodal electrode was inserted in adjacent gingival mucosa. Cathodal and anodal electrodes were moved to the upper and lower canine, upper fourth premolar, and lower first molar teeth for stimulation; baseline REMP was recorded. A 25-gauge 1-cm needle was inserted 0.5 cm into the infraorbital canal. A 25-gauge 1-cm needle was inserted 1 cm rostral to the angular process of the ramus, and advanced 0.5 cm along the medial aspect. Chloroprocaine was injected at each site. Each tooth was stimulated every 10 minutes for 90 minutes. RESULTS: REMP was abolished within 10 minutes for all upper teeth, except for the upper canine tooth in 1 cat, and abolished within 10 minutes for lower teeth in 4 cats. In 1 cat, REMP was not abolished in the lower first molar tooth. In 3 cats, REMP was not abolished in the lower canine and first molar teeth. At 90 minutes, REMP was restored for all teeth except the lower canine tooth in 1 cat, for which REMP was restored at 120 minutes. CONCLUSIONS AND CLINICAL RELEVANCE: Regional anesthesia of the infraorbital and inferior alveolar nerves may provide dental analgesia in cats.

Anesthesia, Conduction↗

PubMed1989

Analysis of abutment tooth movement utilizing mandibular kinesiography (MKG). Part 2. Effects of clasp design in unilateral free-end denture.

The three-dimensional dynamic movement of the abutment tooth was successfully analyzed on a simulation model utilizing the mandibular kinesiography. When the unilateral free-end denture retained by the RPA, RPI or Aker's clasp was subjected to various directions of loads, the abutment tooth was inclined mainly by the sliding displacement of the denture over the alveolar ridge and the lever action around the denture. The Aker's clasp assembly induced the largest tooth movement. The RPA clasp generally exhibited similar tendencies to the Aker's clasp, showing a larger tooth inclination in the disto-buccal direction. The RPI clasp seemed to be preferable for protecting the periodontal tissues from damage associated with unfavorable tooth movements since it induced less distal tooth inclination.

Dental Abutments↗

PubMed2000

A simple method for single anterior tooth replacement.

PURPOSE: This article reports a case in which a recently extracted tooth was used as a natural tooth pontic bonded to the teeth on either side of the missing tooth using a Ribbond ribbon. MATERIALS AND METHODS: A bondable, reinforcing polyethylene ribbon was used to bond a natural tooth pontic to adjacent teeth. RESULTS: Acceptable esthetics were obtained and the result was satisfactory for the patient. CONCLUSION: After one year of clinical use, direct construction of a single-tooth replacement using the natural tooth pontic still provided satisfactory esthetics and function. The technology which makes this adhesive restoration possible is the development of a high strength, high molecular weight, biocompatible polyethylene fiber. This easily handled material must be evaluated in long-term clinical studies.

Acid Etching, Dental↗

PubMed1999

[Human tooth tissue as dental restorative material].

With the recent development of copy-milling systems for porcelain, it has now become possible to construct fitting restorations from natural human tooth substance. This preliminary study aimed to find out whether it is possible to produce a well fitting Class II inlay from an extracted tooth using a copy-milling machine, so that the inlay produced will have enamel over its whole outer surface and dentine on its inner surface. Two pairs of matching sound extracted permanent molars were used. The molars were matched for mesio-distal size of the tooth crown and the convexity of the approximal surfaces. One tooth of each pair was assigned to be the 'donor' tooth, the other tooth being the 'host'. MO inlay preparations were made in the 'host' teeth. These were restored with the milled 'natural inlays' produced from the 'donor' teeth using the CELAY system. The restored 'host' teeth were sliced and examined using light-microscopy. All specimens showed a good fit and the desired location of enamel and dentine. The milling accuracy was assessed in a second experiment. This experiment showed similar marginal gaps for 'natural inlays' as for ceramic inlays. This study has shown that by using the CELAY milling machine it is possible to 'recycle' extracted teeth for the production of accurate restorations.

Dental Cavity Preparation↗

PubMed2002

The effects of loading locations and direct retainers on the movements of the abutment tooth and denture base of removable partial dentures.

The purpose of this study was to evaluate the degree and amount of movement of the abutment tooth and denture base influenced by the direct retainer of distal extension removable partial denture and the location of functional loading, then to suggest direct retainer design with minimal adverse effect and with optimum functional loading location for residual tissue. The displacement of the abutment tooth and inclination of the denture base were determined, with 30 N as work load utilizing simulation model and strain gauge system, about two types of direct retainers with mesial or distal rest and nine loading points on denture base. Displacement and inclination was determined with the one-way analysis of variance and Scheffe's multiple test was performed. The results revealed that type of direct retainer influenced on the magnitude rather than direction of the abutment tooth displacement. The distal displacement of abutment tooth was significantly less in Type M clasp (with mesial rest and connection) than in Type D clasp (with distal rest and connection) (p<0.05). The location of loading points influenced both of the magnitude and direction of the abutment tooth and denture base movement. Posterior and lingual loading resulted in significantly distal displacement of abutment tooth (p < 0.05).

Analysis of Variance↗

PubMedDate not supplied

Effects of oral health education and tooth-brushing on mutans streptococci infection in young children.

PURPOSE: The purpose of this study was to examine the effects of maternal dental health education and tooth-brushing instruction on the levels of mutans streptococci in pre-school children. METHODS: One hundred and seven children (44 boys and 63 girls) with a mean age of 20.5 months, randomly selected from a community child health clinic within a 2-week period, participated in this study. Medical, dental, and dietary information was obtained through a questionnaire. The children's mouths were examined, and plaque samples were obtained by swabbing the teeth and mucosa. A commercial microbiological kit was used to determine the presence of mutans streptococci. The mothers were instructed in tooth-brushing using a soft-scrub method. The children were recalled to the same clinic after a period of 4 weeks to obtain a second evaluation of the mutans streptococci levels. RESULTS: At the first visit, 69 of the 107 children (64%) showed positive infection with mutans streptococci. Ninety (84%) children returned for the recall examination. In the second examination, only 44 (49%) of the 90 children showed positive results for mutans streptococci. The difference in number of children who tested positive is statistically significant (P < .01). At the first visit, children who did not show infection with mutans streptococci were those who reported greater frequency of tooth-brushing (P < .05) and less snacking (P < .05). There were 26 children (29%) who converted from positive to negative results for mutans streptococci infection between the first and second visits (P < .01). This conversion from positive to negative infection was attributed mainly to increased tooth-brushing, as other dental health habits remained the same. CONCLUSIONS: Infection with mutans streptococci in young children is associated with increased snacking frequency and inadequate tooth-brushing. A single dental health education session and tooth-brushing instruction to mothers results in approximately a 25% reduction in mutans streptococci infection in young children from a relatively high socioeconomic status.

Child, Preschool↗

PubMed2001

[The expression and distribution of Smad 2 in human tooth germ].

OBJECTIVE: To investigate the expression of Smad 2 gene in human tooth germ,and the possible function of Smad 2 during human tooth germ development. METHODS: Immunohistochemical staining on prepared specimens of different stages of developing human tooth germ. RESULTS: Smad 2 expression had specific temporal-spatial pattern during tooth germ development, which was similar to TGF-beta. CONCLUSION: The expression of Smad 2 gene in tooth germ was detected in different stages of human tooth germ. The results suggest that Smad 2, one of the intracellular downstream molecules of TGF-beta, and as an inductive signal mediating epithelial-mesenchymal interaction, may regulate the differentiation of ameloblast and odontoblast cells, and modulate dentinogenesis and amelogenesis.

English Abstract↗

PubMed2004

Influence of loading positions of mandibular unilateral distal extension removable partial dentures on movements of abutment tooth and denture base.

PURPOSE: The aim of our study was to explore the effects of different loading positions on the movements of the abutment tooth and denture base of removable partial denture with unilaterally designed framework (RPD-U). MATERIALS AND METHODS: The experiment was carried out with a simulation model of a mandible without left molars. The movements of abutment tooth and denture base of the unilateral and bilateral designs were due to 30N vertical load on 12 loading positions determined with a strain gauge circuitry. The effects of loading positions on the movements of the abutment tooth and denture base were compared between two designs. RESULTS: During the loading on buccal, lingual positions, and the most disto-central position the movements of the abutment tooth and denture base of the unilateral design were significantly greater than those of the bilateral design (P < 0.01). During the loading on the three mesio-central positions the movements of the abutment tooth and denture base were equal between designs, and were significantly lower than during the loading on the other positions (P < 0.01). CONCLUSION: Ending the denture teeth at the mesial cusp of second molar and positioning the occlusal contacts over the ridge crest adequately stabilize the abutment tooth and denture base of RPD-U.

Acrylic Resins↗

PubMed1981

The detection of sleep apnea in the awake patient. The 'saw-tooth' sign.

We studied 21 subjects, 13 of whom had the sleep apnea hypersomnolence syndrome associated with upper airway obstruction during sleep (SAHS-UAO) to determine if "saw-toothing" on the flow-volume loop was significantly associated with the phenomenon of airway occlusion during sleep. A "saw-tooth" pattern was present on the flow-volume loop in 11 of 13 subjects with SAHS-UAO. The presence of saw-toothing correlated with fluttering of tissue that was visualized in the upper airway via the fiberoptic bronchoscope. The specificity of the saw-tooth pattern for SAHS-UAO was 100%. Generalized obesity may indirectly influence the presence of saw-toothing due to deposition of what appeared to be adipose tissue in the pharyngeal walls. Although the number of subjects in this study is small, saw-toothing on the flow-volume loop appears to be an important aid in the diagnosis of SAHS-UAO.

Adolescent↗

PubMedDate not supplied

Comparison of temperaments of children with and without baby bottle tooth decay.

Several demographic studies have been done to identify children at risk for Baby Bottle Tooth Decay (BBTD). Discussions have described these children with Baby Bottle Tooth Decay as strong tempered, cranky, restless, and fussy. The parents of these children have acknowledged these behaviors. To determine whether there were differences in temperament, children with Baby Bottle Tooth Decay were compared with children without Baby Bottle Tooth Decay by assessing the nine temperament components described by the Toddler Temperament Scale (TTS) questionnaire. Parents completed the temperament questionnaire and ninety-two children between twelve and thirty-six months old were studied. Scores for the nine temperament components were tabulated and temperament difficulty was determined as defined by the authors of the toddler Temperament Scale. At-test comparison between the two groups revealed no significant difference for the nine temperament components. There was also no difference when comparing clusters of the nine components. The conclusion is that there is no difference in the temperaments between the group of children with Baby Bottle Tooth Decay and the comparison group of children without Baby Bottle Tooth Decay.

Adaptation, Physiological↗

PubMed1996

Expression of neurotrophin receptors during rat tooth development is developmentally regulated, independent of innervation, and suggests functions in the regulation of morphogenesis and innervation.

Low-affinity neurotrophin receptor (LANR) and trk receptor tyrosine kinases (trks) serve as low- and high-affinity receptors for neurotrophins. Besides promoting the development and maintenance of the mammalian nervous system, it has been suggested that neurotrophins may have broader functions in the development of non-neuronal tissues. To evaluate the possible roles of neurotrophic factors in tooth development, we performed a detailed examination of the expression patterns of neurotrophin receptors during development of the rat tooth from initiation to completion of crown morphogenesis. mRNA expression was studied by in situ hybridisation and LANR protein was localised by immunohistochemistry. Furthermore, dissected tooth germs were cultured in vitro to examined the role of trigeminal innervation in the expression of neurotrophin receptors. mRNAs for LANR, trkB, and trkC, but not trkA, were detected in developing teeth. LANR and the truncated form of trkB, which lacks the intracellular tyrosine kinase domain, were expressed throughout tooth morphogenesis and their expression patterns were largely non-overlapping and changed spatio-temporally. trkC was expressed after birth, and it was restricted to dental papilla mesenchyme. The expression of all receptors correlated with the development of innervation, but, in addition, the expression of LANR and trkB appeared to be associated with cell differentiation and epithelial-mesenchymal interactions. The patterns of LANR, trkB, and trkC in teeth which underwent morphogenesis in organ culture were similar to those in vivo, which indicates that the expression of these neurotrophin receptors is not regulated by and does not depend on trigeminal innervation. The data suggest that neurotrophin receptors have roles in the development of tooth innervation, but that they also have non-neuronal, organogenetic functions.

Aging↗

PubMed1977

Regeneration of tooth development in vitro following sodium fluoride treatment.

Mandibular incisors were dissected from the jaw of 15- and 16-day C57BL/10 mouse embryos and cultured on agar-solidified Eagle's basal medium supplemented with fetal calf serum, an antibiotic, and glutamine, The experimental medium was the same as the control except that fluoride was added such that the final concentrations ranged from 2.0-8.0 mM NaF. Control and experimental explants were recovered after two, four and six days of incubation and studied histologically. After two days of fluoride treatment (3.0 mM NaF), cellular degeneration was observed in the dental papilla mesenchyme while the enamel organ epithelium appeared more resistant. Prolonged treatment or treatment at higher concentrations resulted in destruction of the dental papilla. The enamel organ was still present but was abnormal and reduced. Older tooth germs were less affected overal when incubated at the same fluoride dosage and time of treatment. When explants subjected to limited exposure (2 days) to fluoride were placed on control medium, the suppressed tooth germs recovered. The recovery was enhanced by grafting untreated mesenchyme to the treated explants followed by incubation on control medium. The observations indicate that NaF can suppress the development of tooth germs in vitro and that recovery from the suppresion does occur. The more severe inhibition observed in the mesenchymal component when compared to the response of the epithelial component of the treated explants suggests that fluoride may alter the ultimate morphology of the tooth crown by disrupting the normal epithelial-mesenchymal interaction which occurs during early tooth development.

Animals↗

PubMed2001

Tissue contributions to sex and race: differences in tooth crown size of deciduous molars.

This study describes size of constituent deciduous tooth crown components (enamel, dentine, and pulp) to address the manner in which males characteristically have larger teeth than females, and the observation that teeth of American blacks are larger than those of American whites. Measurements were collected (n = 333 individuals) from bitewing radiographs using computer-aided image analysis. Tissue thicknesses (enamel, dentine, pulp) were measured at the crown's mesial and distal heights of contour. Deciduous mesiodistal molar crown length is composed of about 1/7 enamel, 1/3 dentine, and 1/2 pulp. Details differ by tooth type, but males typically have significantly larger dentine and pulp dimensions than females; there is no sexual dimorphism in marginal enamel thickness. Males scale isometrically with females for all variables tested here. Blacks significantly exceed whites in size of all tissues, but tissue types scale isometrically with blacks and whites with one exception: enamel thickness is disproportionately thick in blacks. While the absolute difference is small (5.56 mm of enamel in blacks summed over all four deciduous molar tooth types vs. 5.04 mm in whites), the statistical difference is considerable (P < 0.001). Aside from enamel, crown size in blacks is increased proportionately vis-à-vis whites. Principal components analysis confirmed these univariate relationships and emphasizes the statistical independence of crown component thicknesses, which is in keeping with the sequential growth and separate embryonic origins of the tissues contributing to a tooth crown. Results direct attention to the rates of enamel and dentine deposition (of which little is known), since the literature suggests that blacks (with larger crowns and thicker enamel) spend less time in tooth formation than whites.

Anthropology, Physical↗

PubMed2005

Plasticity of the cortical dentition representation after tooth extraction in naked mole-rats.

Naked mole-rats (Heterocephalus glaber) have a large cortical representation of their behaviorally important front teeth, accounting for 30% of primary somatosensory cortex (SI). Here we investigated the plasticity of this dental representation after the extraction of a single lower tooth. The representation of the contralateral lower incisor normally accounts for approximately 15% of somatosensory cortex in mole-rats. In five mole-rats the lower right incisor was extracted on either postnatal day 7 or 21. After 5-8 months the deprived tooth zone in S1 was investigated with multiunit microelectrode recordings. The results revealed a dramatic reorganization of the orofacial representation in SI. Neurons in the cortical lower tooth representation were responsive to tactile inputs from surrounding orofacial structures, including the contralateral upper incisor, ipsilateral lower incisor, tongue, chin, gums, and buccal pad. Neurons in the former lower tooth zone had complex receptive fields that often encompassed multiple sensory surfaces surrounding the extracted tooth in the periphery. These results suggest that the representation of the dentition in mammals is capable of significant reorganization after the loss of sensory inputs from the teeth. These data parallel findings in the somatosensory hand area of primates after deafferentation where cortex can become activated by a mixture of widely spaced surrounding sensory surfaces (e.g., chin and upper arm).

Afferent Pathways↗

PubMed2001

Orthodontic tooth movement in the mixed dentition. Histological study of a human specimen.

MATERIAL AND METHOD: We present a retrospective analysis of periodontal tissue reactions and clinically relevant phases of permanent tooth eruption and deciduous tooth resorption after half a year of orthodontic tooth movement in the upper and lower jaw of a deceased male (age 9 years 3 months). Specimens of the horizontal plane (lower jaw) and sagittal plane (upper jaw) were prepared by the ground microsection technique without prior decalcification. RESULTS: Histologically, reactions in the periodontal ligament presented as characteristic appositional/resorptive metaplastic processes in the areas of tension and pressure, with side effects such as root resorption and periodontal necrosis being only minor. In the upper jaw, an erupting permanent canine was closely associated with the tooth germ of the first premolar. Resorptive follicle activity had resulted in extensive erosion of the interradicular bone and root resorption in the area of the first premolars. CONCLUSION: These findings suggest that it might prove useful to take critical topographic findings as parameters for differential therapeutic decisions. Follicle-driven deciduous tooth resorption presenting partly as resorption lacunae and partly with linear characteristics was accompanied by resorptive/appositional remodeling of the alveolar socket as well as regressive changes in the supracrestal fibers of the marginal gingiva.

Child↗

PubMed1984

Tooth transplantation with the periodontium intact: a histometric analysis.

A method was devised, from a pilot study, for transplanting a root-treated tooth with an intact periodontium into a newly prepared socket to assess whether the prognosis for transplantation procedures could be improved. Five male vervet monkeys were used for the definitive study. The mandibular central incisors were extracted from each monkey and the sockets were allowed to heal for 5 weeks. Thereafter a window of gingiva overlying each of these healed receptor sites was removed and the sockets were prepared with tapered burs. The distal root of the mandibular second molar was used as the transplant tooth and the distal root of the first molar as the control tooth. The transplant tooth was removed, together with surrounding alveolar bone which was then trimmed to a thickness of approximately 1 mm. The control tooth was extracted with root forceps. After transplantation, the teeth were splinted to the adjacent incisors for 3 weeks. After 8 weeks the healing process was examined histologically, both qualitatively and quantitatively. Replacement resorption (ankylosis) was not observed. Student's t test for paired samples revealed that the incidence of secondary cementum formation was significantly greater on the control teeth. The minimization of trauma may be the reason ankylosis did not occur.

Alveolar Process↗

PubMed1995

Immunohistochemical and electron microscopic demonstration of nerve fibres in relation to gingiva, tooth germs and functional teeth in the lower jaw of the cichlid Tilapia mariae.

Immunohistochemistry revealed the presence of numerous neurofilament (NF)-like immunoreactive axons in relation to gingiva and dental follicles surrounding mineralizing tooth germs. The gingival nerve fibres frequently approached the prospective papilla of early tooth primordia. Electron microscopic (EM) analysis revealed the presence of bundles of unmyelinated axons immediately below the epithelial-proprial junction of the gingiva. Bundles of nerve fibres were also present in the border zone between the prospective papilla of bud-stage tooth germs and surrounding mesenchyme and in close proximity to blood vessels of the follicles surrounding older tooth germs, but no axons were observed within the emerging dental papilla. In the individual functional tooth, a bundle of NF-like immunoreactive nerve fibres entered the apical part of the pulp forming a subodontoblastic plexus at mid-pulpal levels. EM analysis showed that the apical bundle consisted of many unmyelinated and a few myelinated axons invested by Schwann cell processes. The subodontoblastic plexus contained unmyelinated axons only. Thin, axon-like profiles were also seen in predentinal tubules. Nerve fibres were not observed at pulpal horn levels and in the ligamentous attachment. It is concluded that both immature and mature parts of the lower-jaw dentition of the cichlid T. mariae are innervated and that the microscopic anatomy of this innervation is partly similar to the pattern seen in developing and adult mammals.

Animals↗

PubMed1986

Innervation of the dental pulp during tooth succession in the cat.

The possibility that axons branch to supply the pulps of both the upper deciduous canine tooth and its permanent successor has been investigated by stimulating the pulp of one tooth and recording from the pulp of the other. In cats less than about 14 weeks of age, the permanent canine was too poorly developed to allow electrodes to be applied to it satisfactorily. In 5 of 14 preparations in cats aged 14-23 weeks, compound action potentials were recorded in one canine during stimulation of the other. These responses were not abolished by sectioning the infraorbital nerve or its canine branch in the floor of the orbit or by paralysing the animal, but they were abolished by sectioning the pulp of the permanent canine, indicating that they were due to branched axons. In preparations in which there was no tooth-to-tooth response, there was usually evidence that the pulp of one or other of the teeth did not have a functional innervation. The results indicate that at least some of the nerves which supply the pulp of a deciduous tooth are retained to supply its permanent successor.

Aging↗