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PubMedDate not supplied

Caries rates for the mesial surface of the first permanent molar and the distal surface of the second primary molar from 6 to 12 years of age in Sweden.

The aim was to analyse the pattern of caries rates in enamel and dentin of the mesial surface of the first permanent molar (mesial 16, 26,36,46; here called 6m) and the distal surface of the second primary molar (distal 55,65,75,85; here called 05d) from 6 to 12 years of age. The material consisted of retrospectively collected bite-wing radiographs of a cohort of 374 children aged 5-7 years at baseline and followed to 11-12 years of age. The following scoring system was used: score 0 = no visible radiolucency, 1-2 = radiolucency in the outer (1) or inner (2) half of the enamel up to the enamel-dentin border, 4 = radiolucency with obvious spread in the outer half of the dentin, and 5 = radiolucency in the inner half of the dentin. Two transitions were used: state 0-2 = the time lapse from state 0 until the lesion had reached state 2, and state 2-4 = the time lapse from state 2 until the lesion had reached state 4 or 5. At the age of 9, the mean defs (decayed, extracted and filled surfaces) of 05d was 0.70 and the mean DFS of 6m was 0.19. The enamel caries rates (state 0-2) were 4.6 new lesions/100 tooth surface-years for 6m and 11.3 for 05d. The dentin caries rates (state 2-4) were 20.5 new lesions/100 tooth surface-years for 6m and 32.6 for 05d. In conclusion, the enamel caries rate for 05d was more than twice that for 6m. Both surfaces had relatively high dentin caries rates, indicating that for these surfaces between 6 and 12 years of age, the rate of progression into the dentin is generally relatively high once the lesion has reached the inner half of the enamel as judged radiographically.

Age Factors↗
PubMed1996

Comparison of the crown dimensions between the maxillary second deciduous molar and the first permanent molar.

The morphologic relationship of the crown structures of the maxillary second deciduous molar (m2) and the first permanent molar (M1) was investigated with odontometric methods. Materials used were 124 male dental casts taken from Chinese living in Kaohsiung (Taiwan). The mesiodistal and buccolingual diameters, cusp sizes, and intercusp distances were measured. The mean crown diameters were larger in M1 than in m2. The tooth crown proportions were similar in m2 and M1. The intercusp distance was compressed buccolingually in m2. With respect to the relative cusp size, the paracone was not significantly different between m2 and M1. The metacone was relatively larger in m2 than M1, while lingual cusps (protocone and hypocone) were relatively smaller in m2 than in M1. Principal component analysis was performed to investigate factors influencing the variation in crown dimensions of the two teeth. Four components were extracted: (1) buccolingual intercusp distances, (2) crown proportion (mesiodistal and buccolingual diameters), (3) mesiobuccal and distolingual compression, and (4) protocone and mesiodistal intercusp distance. Analysis of principal component scores indicated that the crown proportions of m2 and M1 were similar. The m2 had a smaller protocone and more buccolingually compressed intercusp distances than did M1. The morphologic characteristics of the crown of m2 indicate that it is more primitive and has developed less than M1.

Humans↗
PubMed1975

[The condition of the 2d milk molars and the 6 year molars in a Copenhagen suburban community].

The increase in fillings, i. e. in caries, of the second deciduous and first permanent molars was recorded for a period of 18 months, using the dmfs/DMFS index, in 117 children, aged from 7 to 9 years, of the Copenhagen suburb of Brøndby. According to the findings concerning the second deciduous molars, the children were subdivided into three groups of caries incidence. The three groups differed but little in caries progression, which may be explained by the fact that the school dental service ensures the regular treatment of the children and achieves fairly stable results.

Child↗
PubMed1976

[Therapeutic problems in the infraposition of deciduous molars and molars].

Reflections on the nomenclature, aetiology and genesis are followed by seven case reports. Apart from the description of a new aspect of genesis and apart from therapeutical discussions of the single case, the authors draw some conclusions. The infraposition of deciduous molars requires orthodontic therapy, whereas that of permanent molars necessitates treatment at a special clinic. Suggestions for desirable further studies mark the end of the paper.

Adolescent↗
PubMed1996

Mouse molar morphogenesis revisited by three-dimensional reconstruction. II. Spatial distribution of mitoses and apoptosis in cap to bell staged first and second upper molar teeth.

Tooth morphogenesis is a complex multifactorial process in which differential mitotic activities and cell death play important roles. Upper first (m1) and second (m2) molars from mouse embryos were investigated from early cap to bell stage. m2 differed from m1 by delayed origin of the enamel grooves delimiting the protrusion of the cap bottom towards the dental papilla, and retardation of the enamel knot formation. The width of the m2 enamel organ was conspicuously smaller during cap formation and length remained smaller throughout the period of observation. Formation of the cap depression was comparable in m1 and m2, however margins delimiting the enamel organ cavity arose in m1 and m2 as mirror images. Attempts were made to correlate changes in the distribution of apoptotic cells and bodies and/or mitoses with morphogenesis. These cellular activities were recorded from histological sections and represented in space using computer-assisted three-dimensional reconstructions. Mitoses in the epithelial compartment were associated with the development of the cervical loop. In the mesenchyme of m1 at early bell stage, a postero-anterior increasing gradient of mitoses was observed which might be correlated with the anterior growth of the molar. Cells in the enamel knot demonstrated a high level of apoptosis, retarded in m2, but absolutely no division. Apoptotic processes were also involved in the anterior delimitation of the m1 epithelium. Apoptosis might correspond to the programmed destruction of cells whose function had to be suppressed or whose potential activity had to be avoided.

Animals↗
PubMed1994

Molar distalization with bimetric molar distalization arches.

The aim of this study was to observe the clinical and cephalometric effects of intra-oral distalization with the maxillary bimetric arches. 3 girls and 1 boy with a mean age of 13.5 years with Class II skeletal and dental relationship were selected. Care was taken to select patients having a normal vertical growth pattern. Lateral cephalograms were taken at the beginning and at the end of the distalization period, which was approximately 3 months. To observe the distal movement, a metal marker was attached to the distal end of the buccal tube of the first molar. On each lateral cephalometric radiograph a reference plane perpendicular to the occlusal plane and passing through the point Sella was drawn to assess the amount of distalization. Cephalometric measurements indicated that the upper molars moved approximately 3 mm distally and that the lower incisors were proclined.

Adolescent↗
PubMed2005

Molar mass and molar mass distribution of polystyrene particle size standards.

Monodisperse polystyrene microspheres and nanospheres are often used as particle size standards for calibration of size-measuring instruments. They are potentially useful as the mass standards for particle mass spectrometry as well. We demonstrated in this work that it is possible to achieve high-precision mass determination for single polystyrene spheres using a quadrupole ion trap. We introduced the particles into the trap by laser-induced acoustic desorption and probed them with light scattering. Mass-to-charge ratios of the individual particles were determined from applied trap-driving frequencies, voltage amplitudes and the observed starlike oscillatory trajectories projected on the radial plane. Creation of one-electron differentials through charge-state changes by electron bombardment allowed determination for the absolute mass of a single trapped particle to a precision better than 0.1%. Both molar mass and molar mass distribution were deduced from a large number of measurements for NIST polystyrene particle size standards (SRMs 1690 and 1691). Our results are in excellent agreement with the size measurement for the 0.895-microm spheres (NIST SRM 1690), but a small discrepancy (4%) in number-average mass was found for the 0.269-microm spheres (NIST SRM 1691).

Journal Article↗
PubMed1994

Influence of base composition, base sequence, and duplex structure on DNA hydration: apparent molar volumes and apparent molar adiabatic compressibilities of synthetic and natural DNA duplexes at 25 degrees C.

Using high-precision densitometric and ultrasonic measurements, we have determined, at 25 degrees C, the apparent molar volumes, phi V, and the apparent molar compressibilities, phi KS, of five natural and three synthetic B-form DNA duplexes with varying base compositions and base sequences. We find that phi V ranges from 152.0 to 186.6 cm3 mol-1, while phi KS ranges from -73.0 x 10(-4) to -32.6 x 10(-4) cm3 mol-1 bar-1. We interpret these data in terms of DNA hydration which, by the definition employed in this work, refers to those water molecules whose density and compressibility differ from those of bulk water due to interactions with the DNA solute. This definition implies that hydration depends not just on the quantity but also on the quality of the solvent molecules perturbed by the solute. In fact, we find that the number of water molecules perturbed by the DNA duplexes (the quantity of water in their hydration shells) is approximately the same for all of the B-form double helixes studied, while the quality of this water differs as measured by its density and compressibility, thereby yielding differences in the overall hydration properties. Specifically, we find a linear relationship between the density and the coefficient of adiabatic compressibility, beta Sh, of water in the hydration shell of the DNA duplexes, with the range of values for beta Sh being only 65-80% of the value of bulk water.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Composition↗
PubMed1992

Tetraploidy in human placenta. A dilemma in molar and non-molar pregnancies.

17 cases of partial molar pregnancy were analysed cytogenetically by the direct-preparation method. Eight partial moles were triploid, 7 diploid/tetraploid mosaic, and 2 tetraploid. In the course of prenatal cytogenetic screening, out of 1,263 chorionic villus samplings, 2 tetraploid and 1 diploid/tetraploid cases were found. These cases of partial moles do not fit into the usual patterns of triploid partial moles. The findings presented here suggest that different causative factors may be involved in the origin of molar degenerations. These results also call to attention that tetraploidy is an existent and relatively common abnormality.

Adult↗
PubMed2005

Formocresol and ferric sulfate have similar success rates in primary molar pulpotomy. In carious primary molars does a pulpotomy performed with ferric sulphate, compared with formocresol, result in greater clinical/radiographic success?

DATA SOURCES: Medline Ovid Library, the Cochrane Library, PubMed, Embase, Science Citation Index (SCI) and System for Information on Grey Literature in Europe (SIGLE). STUDY SELECTION: Reviews, full reports, or research abstracts of prospective, retrospective, comparative, and/or radiographic studies were included, while case reports and letters were excluded. DATA EXTRACTION AND SYNTHESIS: A total of 13 studies (three randomized clinical trials and 10 clinical trials) contributed to the meta-analysis, one randomized clinical trial and one clinical trial were analyzed by the direct technique, and all 13 trials were analyzed by the indirect technique. Data from trials were divided into clinical and radiographic data, and separate statistical analyses were conducted using the direct technique. Odds ratios (ORs) were used to compare the relative success of ferric sulphate and formocresol. Data homogeneity was tested using the chi(2)-test of consistency on the ORs for each trial. RESULTS: Clinical data indicated that ferric sulphate was significantly more successful than formocresol (OR=1.95; CI=1.01-3.80). Radiographic data indicated no difference between medicaments (OR=0.90; CI=0.58-1.39). Medicaments did not differ with t-tests of clinical (P>0.10) and radiographic (P>0.50) data. CONCLUSIONS: In human carious primary molars with reversible coronal pulpitis, pulpotomies performed with either formocresol or ferric sulphate are likely to have similar clinical/radiographic success.

Comment↗
PubMed1987

Villous alpha-fetoprotein in molar and non-molar abortuses.

The alpha-fetoprotein (AFP) content of chorionic villi from elective and spontaneous abortuses, diploid androgenetic and paternally derived triploid conceptuses was measured by a radioimmunoassay technique and related to the presence of fetal parts and chromosome constitution. AFP values above 10 kIU/l were detected in villi from all chromosomally normal conceptuses, except for one without fetal parts, and also in nine out of 13 triploid conceptuses and 19 out of 27 diploid androgenetic conceptuses. Early fetal demise may explain villous AFP concentrations below 10 kIU/l in one karyotypically normal and four triploid abortuses. The finding of immunoreactive, genuine AFP in diploid androgenetic molar conceptuses, assumed to be anembryonic, indicates AFP synthesis by abnormal trophoblastic tissue and intravesicular accumulation of AFP.

Animals↗
PubMed2001

The molarity of molecular theory and the molecularity of molar theory.

Dinsmoor (2001) rejects shock-frequency reduction as a reinforcer for avoidance behavior, and considers this to be an invalidation of so-called molar avoidance theory. This is a narrow view of operant avoidance theory, for which shock-frequency reduction is by no means the only reinforcer.

Animals↗