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At least 37 records · Page 2Linked to original sources
PubMed1986

Influence of changes of tooth temperature on reflex and central activity evoked by stimulation of tooth pulp afferents.

The importance of the temperature of the dentine was studied in teeth prepared for electrical stimulation. During experiments with the mouth open, the temperature of teeth covered by cement was normal. The digastric EMG and the brainstem--evoked response following electrical stimulation of the tooth pulp as well as the threshold for eliciting a jaw-opening response remained constant throughout prolonged experiments. However, heat produced by the cement used to fixate the tooth electrodes could have damaged the tooth if the dentine temperature had exceeded 45 degrees C. A careful preparation of the tooth pulp by repeated application of thin layers of cement allowed an adequate preparation without damage to tooth pulp afferents.

Animals↗
PubMed1975

The use of laser beams for measuring tooth mobility and tooth movements.

The laser reflexion method, a direct contactless measuring technique with a high accuracy, has been applied for clinical purposes. A prototype has been tested using a laser beam to illuminate a patient's tooth fixed to the equipment by an impression plate. The reflected patterns were thrown onto a screen with a coordinate system and photographically recorded, and the movement of the tooth has been geometrically calculated. The relapse tendency after orthodontic treatment of a patient with periodontal disease and parafunctions was studied by repeated measurements of the left medial upper incisor. By use of the method, it was possible to observe that the velocity of the studied tooth was highest during the 1st day and, besides the horizontal movement, a rotation of the tooth began at the end of the measuring period.

Adult↗
PubMed1992

The relative importance of reasons for tooth extraction in terms of potential tooth years of life lost (PYLL).

The aim of the present study was to introduce the potential tooth years of life lost (PYLL) approach to the analysis of data showing the incidence of tooth extraction according to the reason for extraction and to illustrate its use. Six sets of data from prospective nationwide questionnaire surveys of patients treated by systematic random samples of dentists in five European countries were translated into PYLL. Response rates ranged from 25 to 81 per cent and the number of extracted teeth from 959 to 29,397, according to the study. PYLL in Norway 1988 was calculated using the ages of 85 and 80 as cut-off points, or the average sex-specific remaining life expectancy at the age of extraction; otherwise the age of 85 was used. Mean PYLL for all reasons varied from 40.6 to 46.3 years for Norway in 1988 depending on the cut-off point used. For patients aged 21 and older PYLL85 ranged from 35.7 years for France in 1984 to 42.3 years for Sweden in 1959-61. Employing PYLL changed the rank order of the reasons for extraction based on the number of extracted teeth in some instances. It combined the two dimensions 'incidence of 'potential years of tooth function lost' into a continuous quantitative variable which was easy to understand and simple to handle analytically.

Adult↗
PubMed1986

Lead in teeth: the influence of the tooth type and the sample within a tooth on lead levels.

Different sections of permanent teeth have been sampled and the lead levels estimated using carbon furnace AAS. Very high levels of lead (500-3400 micrograms g-1) and other trace metals (Cd, Cu, Fe and Zn) occur on the surface of the teeth, falling off rapidly a few micrometers into the teeth. Lead levels in the bulk enamel of incisors vary depending on the position within the tooth, the highest values occur on the lingual side near the gums and the lowest levels on the labial side near the tooth top. The ratio of the concentration of lead in enamel to dentine and to circumpulpal dentine was found to be 1:2:6, and within the dentine the lead levels were highest in the root dentine. The root dentine in the permanent teeth of eight, near complete or representative, sets of teeth was analysed for lead. The ratio ([Pb]tooth/[Pb]total set) decreased in the order: first molars greater than central incisors greater than lateral incisors greater than canines greater than premolars greater than second molars greater than third molars. This order inversely correlates with the age of formation or eruption of the teeth, i.e. the older teeth have the highest levels of lead in the dentine. Dentine appears to be the best material to use to estimate lead, particularly in relation to the integrated lead intake of a person. Dentine lead was determined in a small sample of deciduous teeth obtained from children living in rural areas. The levels were found to be slightly less than for children living in new housing urban areas and significantly less than for children living in older houses of urban areas.

Bicuspid↗
PubMedDate not supplied

Eruption of tooth-like structure following the exfoliation of natal tooth: report of case.

Natal teeth, defined as those that are the mouth at birth, are rare: one case in 2,000 to 3,500 births. In this case, that of a nine-month-old Japanese boy, it is reasonable to infer that the tooth-like structure, described as a hard-tissue conglomerate with a bone-like appearance, originated in the remnant of the dental papilla and Hertwig's sheath of the natal tooth. Both dentin and root formation were thereby induced.

Dental Enamel Hypoplasia↗
PubMed1984

Ultrastructure of transganglionic degeneration in brain stem trigeminal nuclei during normal primary tooth exfoliation and permanent tooth eruption in the cat.

Electron microscopy is used to study changes in the axons and terminals in the cat brain stem trigeminal nuclei, main sensory, and partes interpolaris and caudalis, during the process of natural tooth shedding. Areas previously showing light optical argyrophilic degeneration products and adjacent areas lacking this degeneration are included. Various types of alteration occur early during tooth loss, including increased presumed glycogen, increased cytoplasmic density, flocculence, lucency, and neurofilamentous hyperplasia. By the stage of maximum exfoliation, terminals and axons of marked density become prominent in areas showing argyrophilia, whereas nondense forms occur elsewhere. By late eruption ages, all forms of degenerated terminals and axons are rare, but phagocytes are heavily laden with similar forms of debris. The sequence of ultrastructural events is discussed in light of recent studies of transganglionic degeneration, their correlation with light microscopic findings, and the potential implications for central plasticity in this system.

Age Factors↗
PubMed1990

Endodontic management of the avulsed tooth and tooth transplantation.

The major causes of post-transplantation tooth loss following tooth replacement after avulsion (exarticulation) and surgical replacement of impacted maxillary canines (auto-transplantation) are inflammatory root resorption and replacement resorption (ankylosis). This paper attempts to outline the treatment and management of replanted teeth using the current philosophies of splinting, endodontic therapy and the use of calcium hydroxide in the re-attachment of the periodontal ligament (PDL). Clinical research during the past 20 years has provided sufficient information for the development and establishment of a rational and effective program of treatment.

Ankylosis↗
PubMed1990

A 3-year follow-up of a homotransplanted tooth from a tooth bank.

A successful case of homologous tooth transplantation is presented. A maxillary second premolar obtained from a tooth bank was implanted into a fresh central incisor extraction site. A 3-yr follow-up radiograph indicated satisfactory apical healing and minimal replacement resorption. Clinically, the transplantation site was free of symptoms and there was no evidence of periodontal disease or tooth mobility.

Adult↗
PubMed1989

[Adhesion of dental resin to tooth structure--syntheses and adhesion to tooth structure of various aliphatic methacrylates with a carboxylic group].

Twelve aliphatic methacrylates with a carboxylic group [succinate (2 MES, 5 MPeS and 10 MDS), methylsuccinate (2 MEMS, 5 MPeMS and 10 MDMS), maleate (2 MEM, 5 MPeM and 10 MDM) and citraconate (2 MEC, 5 MPeC and 10 MDC)] were synthesized by the addition of four dicarboxylic acid anhydrides to each of three different alkylene chain length hydroxy methacrylates to investigate the relationship between the methacrylate structure and its bonding to tooth. The bond strength of methacrylates to polished tooth surface decreased with increasing alkylene chain lengths under dry conditions, but water immersion reduced this change. The bond strength of succinate and maleate to polished tooth surface was higher than that of methylsuccinate and citraconate under dry conditions. All methacrylates showed high bond strength to etched enamel, with maleate showing the highest bond strength. On the other hand, the bond strength of 2 MEM and 5 MPeM to etched dentin was markedly high, and about 5 microns thick resin reinforced dentin at the interface between etched dentin and resin (2 MEM or 5 MPeM) was observed by SEM and EPMA analysis.

Adhesiveness↗
PubMed1991

[Osteoplastic tooth transposition. Surgical method for orthognathic placement of a single tooth].

The procedure described in this article is based on the surgical subtotal luxation of a tooth-containing alveolar segment and allows the repositioning of single teeth while almost regularly safeguarding tooth vitality. This procedure has proven particularly effective in the treatment of maxillary anteriors, canines and premolars. For patients preferring surgical correction to long-term orthodontic treatment this limited operative intervention allows safe orthodontic alignment. To date, relapses have not been observed in the cases treated. Stable immobilization of up to six weeks postoperatively is achieved by splinting.

Alveolar Process↗
PubMed1989

Trends in tooth loss due to caries and periodontal disease by tooth type.

Although the patterns of dental disease is gradually changing, caries and periodontal disease still account for the most important reason for extractions in most countries. However their relative contributions towards overall tooth mortality figures varies. The aim of this study is to investigate the types of teeth usually associated with extractions due to caries or periodontal disease and its relation to the age at which the tooth was lost. The highest proportion of extractions due to caries occurred between 21 to 30 years of age while that for periodontal disease occurred between 41 to 50 years. For caries, the greatest proportion of extractions involved the posterior teeth. The most frequently extracted teeth due to caries are the molars, in particular the first permanent molar. However, for periodontal disease a slightly greater proportion of anterior teeth were lost than the posteriors. This trend is more marked in the lower jaw than the upper. Overall, extractions related to caries tend to increase posteriorly, while that for periodontal disease tend to increase anteriorly.

Adolescent↗
PubMed1980

Electric currents, bone remodeling, and orthodontic tooth movement. II. Increase in rate of tooth movement and periodontal cyclic nucleotide levels by combined force and electric current.

Piezoelectric currents in mechanically stressed bone were implicated in the activation of bone cells. The objectives of this experiment were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to study the effect of electric-orthodontic treatment on periodontal cyclic nucleotides. Maxillary canines were tipped in five cats by 80 g force. Two groups of five cats each were treated by an electric-orthodontic procedure to one maxillary canine for 7 and 14 days, respectively. Teeth treated by force and electricity moved significantly faster than those treated by force alone. Enhanced bone resorption was observed near the anode (PDL compression site), while bone formation was pronounced near the cathode (PDL tension site). Staining for cyclic nucleotides was increased when electric stimulation was added to the mechanical force. These results suggest that orthodontic tooth movement may be accelerated by the use of locally applied electric currents.

Alveolar Process↗
PubMed1985

Tooth wear, solubility and fluoride concentration of molar-tooth surfaces in rats maintained on simultaneous or separate intake of food and fluoridated drinking water.

Eighty rats, 20 days old, were fed a hard pellet diet and deionized or fluoridated (25 parts/10(6) F-) drinking water respectively for 40 days. Half were maintained on simultaneous food and water intake for 3 h, daily, and the remainder on separate intake of food for 3 h followed by drinking water for 3 h, daily. Scanning electron micrographs of the occlusal surface of right maxillary first molars were used for scoring wear. The mandibular and left maxillary molar surfaces were used for solubility and fluoride concentration determinations. Intake of food and water separately did not affect wear significantly, whereas solubility and fluoride concentration of the molar surfaces were significantly increased. Wear, solubility and fluoride of the molar surfaces respectively were highly significantly increased in the rats provided with fluoridated water. Increase in fluoride uptake is due in part at least to the increase in sites available for uptake due to tooth wear. Acid dissolution of worn tooth-surface enamel is greater than that of intact enamel.

Animals↗
PubMed1992

Maternal smoking and tooth formation in the foetus. I. Tooth crown size in the deciduous dentition.

Altogether 2159 pregnancies among black and white Americans in the Collaborative Perinatal Study and dental casts from the children at the age of 5-12 years were studied to find out the effect of maternal smoking on deciduous tooth crown growth. Minor crown size reduction (2-3%) in some dimensions was found in children whose mothers had smoked during pregnancy. The possible change in dimensions seems to be influenced by sex, race and smoking habit. The critical time periods of the gestational development (16th to 19th) weeks would possibly appear from these data to be targeted by the detrimental effect of maternal smoking. It is concluded that deciduous tooth sizes seem to be greatly unaffected when compared to reduction in birthweight.

Black People↗
PubMed1983

An analysis of tooth position on initial tooth contact.

A closed circuit television movement detector was used to study mandibular movement in the form of tooth tapping, in subjects with no apparent dental disease or malocclusion. The velocity and form of various phases of movement was studied, in the transverse, sagittal and coronal planes, from measurements made on u.v. charts and X-Y recordings. It was shown that closing movements were more direct and faster than opening movements; that initial contact on closing is in a well-defined contact area, followed by a sliding of cusps over each other to a final centric position and that the closing path of the mandible in tapping movements is in the form of a smooth curve showing simple axis rotation through distances normally greater than those accepted clinically. It was also shown that microphone signals can be detected at times other than when normally expected, indicating displacement with tooth contact, at times other than at the fully intercuspated position.

Dental Occlusion, Centric↗