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At least 613 records · Page 34Linked to original sources
PubMed2000

A study on the imaging of complex furcation forms in upper and lower molars.

BACKGROUND, AIMS: The form of the molar roots and their furcated region influence both the pathogenesis of periodontal destruction and therapeutic attempts. METHOD: Using a specially-constructed measuring device, 359 1st and 2nd molars, both upper and lower, were analysed 3-dimensionally. The parameters measured were horizontal furcation concavity, height of root trunk, degree of root taper, the distance between the root prominences adjacent to the furcation entrances and the angle of root separation. RESULTS: The mean horizontal furcation concavity in lower molars was 0.5 mm at a distance of 1 mm apical to the cemento-enamel-junction (CEJ) and 3 mm at the distance of 4 mm apical to the CEJ. The angle of root separation was between 16 degrees (lower jaw molars lingual) and 29 degrees (upper jaw molars distal). The vertical distance from root separation to CEJ averaged 3.3 mm in lower jaw molars and 4.8 mm in upper jaw molars. CONCLUSIONS: Our findings underline the variability of furcation morphology.

Anatomy, Cross-Sectional↗
PubMed2001

Clinical crown height (length)--a review of published measurements.

BACKGROUND, AIMS: Clinical crown height is an objective measure of the position of the gingival margin which could be used in determining the 'normal' position of the gingival margin. The aim of this study was to do a systematic review of published clinical crown heights in the human permanent dentition to compare the measurements and to see if a clear trend with age exists. MATERIAL AND METHODS: An on-line literature search was done using the key words clinical crown height (or) clinical crown length. From January 1975 to August 2000, 11 published papers have listed measurements; three of these report on all tooth types, the remainder on anterior teeth. RESULTS: All studies used the same measuring technique but age group reporting differed as did the tooth types measured. Measurements from the 10 acceptable studies of the clinical crown height of the same teeth are comparable at similar ages, so published values are reasonable estimates of 'normality' for diagnosis. There is a statistically significant increase in clinical crown height of central and lateral incisors with age that slows as age increases.

Age Factors↗
PubMed2002

Mesiodistal size of deciduous teeth in subjects with unilateral cleft lip and palate.

The aim of this study was to investigate whether there was an association between presence of a cleft and reduced size of deciduous tooth on the cleft side. In this investigation, 58 study models of patients with unilateral cleft lip and palate with deciduous dentition were analyzed. The largest mesiodistal dimension of deciduous teeth was measured by a sliding caliper. The size of the same teeth on the side of the cleft and on the non-cleft side was compared. The results of the investigation were statistically analyzed. A difference between the genders was found. In the sample of boys the lateral deciduous incisor and the second deciduous molars on the cleft side were smaller than those on the non-cleft side, while in girls the central and lateral deciduous incisors were smaller on the cleft side than on the non-cleft side. It was concluded that the presence of a unilateral cleft lip and palate was associated with smaller tooth size.

Child, Preschool↗
PubMed2002

Deciduous tooth crown size and asymmetry in strabismic children.

OBJECTIVES: To explore deciduous tooth crown dimensions in strabismic children and the relationship between the type of strabismus and tooth crown mesio-distal (M-D) and labio-lingual (L-L) size asymmetries. MATERIAL: Dental casts at mixed dentition of 2159 Collaborative Perinatal Study black and white children were measured, 123 of them strabismic at 1 year of age, age ranging from 6 to 12 years. METHODS: Directional and fluctuating asymmetries in antimeric teeth were explored in various types of strabismus having unilateral, bilateral or alternating expression. ANOVA and T-square test were used for size comparisons and calculated asymmetries were explored by comparing the variances and Pearson correlations. RESULTS: Strabismus was associated with significant M-D size increase of deciduous maxillary canines in black boys and white girls, black girls had size reduction in their mandibular canine, but white boys were unaffected. Right side size dominance was found in the strabismic children in the lower second deciduous molar M-D dimensions and in the children with alternating strabismus in their upper deciduous canine M-D dimensions. Children with unilateral strabismus had random fluctuating dental asymmetry in their upper deciduous second molar L-L dimensions when compared with healthy normals. Higher left-right correlations were found in lower second deciduous molar dimensions in strabismic girls when compared with that in controls and in strabismic boys, suggesting better developmental canalization in female. CONCLUSIONS: Asymmetries in the head area, such as promoted here in strabismic children, may have associations with asymmetries in the dentition, focusing the embryonal origins and timing of developmental processes.

Analysis of Variance↗
PubMed2002

Different morphotypes of functional dentition in the lower molar region of tabby (EDA) mice.

OBJECTIVES: To sort and classify the highly variable lower molar dentition in tabby (Ta) mice postnatally. The Ta syndome is homologous to the anhidrotic (hypohidrotic) ectodermal dysplasia (EDA) in human and includes severe developmental defects of teeth, hair and sweat glands. DESIGN: Analysis of tooth shape and cusp pattern and measurement of the mesio-distal crown length. SETTING AND SAMPLE POPULATION: Institute of Experimental Medicine, Academy of Sciences, Prague. Fixed heads of 107 tabby (Ta) homozygous and hemizygous mice and 90 wild type mice aged from post-natal day 11 to adulthood, collected during 1995-2001. OUTCOME MEASURE: Identification of distinct morphotypes of Ta dentition. Reduced tooth length in Ta teeth and specific differences in tooth length between distinct morphotypes. RESULTS: The variable dentitions in the lower molar region of Ta mice were classified in two basic morphotypes I and II. The morphotype I was further subdivided into particular morphotypes Ia, Ib and Ic. Proportion of the basic morphotypes I and II was different in the offspring of heterozygous (84% and 12%) compared with homozygous + hemizygous (45% and 52%) mothers. The proportions of particular morphotypes within a basic morphotype were similar in both offspring groups. CONCLUSION: The identification of the distinct morphotypes made possible to classify the structural variability of the mandibular functional dentition in Ta mice.

Animals↗
PubMed2002

Different morphotypes of the tabby (EDA) dentition in the mouse mandible result from a defect in the mesio-distal segmentation of dental epithelium.

OBJECTIVES: Prenatal identification of the different dentition morphotypes, which exist in the lower molar region of tabby (Ta) adult mice, and investigation of their origin. The mouse Ta syndrome and its counterpart anhidrotic (hypohidrotic) ectodermal dysplasia (EDA) in human are characterized by absence or hypoplasia of sweat glands, hair and teeth. DESIGN: Analysis of tooth morphogenesis using serial histological sections and 3D computer aided reconstructions of the dental epithelium in the cheek region of the mandible. SETTING AND SAMPLE POPULATION: Institute of Experimental Medicine, Academy of Sciences, Prague. Heads of 75 Ta homozygous and hemizygous mice and 40 wild type (WT) control mice aged from embryonic day (ED) 14.0-20.5 (newborns), harvested during 1995-2001. OUTCOME MEASURE: Prenatal identification of five distinct morphotypes of Ta dentition on the basis of differences in tooth number, size, shape, position and developmental stage and of the morphology of the enamel knot in the most mesial tooth primordium. RESULTS: The mesio-distal length of the dental epithelium was similar in the lower cheek region in Ta and WT mice. In Ta embryos, there was altered the mesio-distal segmentation of the dental epithelium giving rise to the individual tooth primordia. Prenatally, two basic morphotypes I and II and their particular subtypes (Ia, Ib, Ic, and IIa, IIb, respectively) of the developing dentition were identified from day 15.5. The incidence of the distinct morphotypes in the present sample did not differ from postnatal data. The proportion of the morphotype I and II was dependent on mother genotype. CONCLUSION: The different dentition morphotypes in Ta mice originate from a defect in the mesio-distal segmentation of the dental epithelium in mouse embryos. This defect presumably leads to variable positions of tooth boundaries that do not correspond to those of the WT molars. One tooth primordium of Ta mice might be derived from adjacent parts of two molar primordia in WT mice.

Animals↗
PubMed2003

Prediction of mesiodistal canine and premolar tooth width in a sample of Peruvian adolescents.

OBJECTIVES: To compare the predicted tooth width measurements of permanent canine and premolars from Tanaka-Johnston regression equations and Moyers probability tables with the in situ measurements in a sample of Peruvian adolescents. DESIGN: Cross-sectional. SETTING AND SAMPLE POPULATION: Trujillo, Peru; 248 dental casts were measured using a sliding caliper with a Vernier scale rounded to 0.1 mm. RESULTS: Tanaka-Johnston regression equations were not precise, except for the upper arch in the male sample. For females, the Moyers 95th percentile in the upper arch and the 65th percentile in the lower arch predicted the sum precisely. For males, the Moyers 65th percentile for the lower arch predicted the sum precisely, but none of the Moyers percentiles provided precise prediction in the upper arch. CONCLUSIONS: Using tooth width prediction methods from a different racial origin could create an under- or overestimation of the actual combined canine and premolar tooth width, although their clinical significance is disputable.

Adolescent↗
PubMed2003

Prevalence of tooth-size discrepancy among different malocclusion groups.

This study was designed to estimate the prevalence of tooth-size discrepancy as a factor of skeletal malocclusion in the orthodontic patient population of the Campania region. The study employed the pretreatment models of 94 patients. The mesiodistal diameters of teeth were measured by digital electronic calipers (accurate to 0.01 mm) and Bolton's indices were calculated. The sample was grouped into three malocclusion groups based on the values of Steiner cephalometric analysis. Multiple regression analysis data indicated a significant linear relationship (r2 = 0.99, P = 0.0000) for Bolton's posterior, anterior and total indices. The discriminant multivariate analysis, based on stepwise Wilke's lambda, revealed five variables capable of classifying 88.6% of the sample in the four malocclusion groups. As no relationship between the four groups identified by the discriminant analysis and the types of skeletal malocclusions exists, it was unequivocally concluded that there is no evidence of any predisposition for a tooth-size discrepancy in any of the malocclusion groups.

Cephalometry↗
PubMed2002

Clinical and radiographic features of a family with autosomal dominant amelogenesis imperfecta with taurodontism.

This paper describes the clinical features of a family of four generations with autosomal dominant amelogenesis imperfecta with taurodontism (ADAIT). Considerable variation in phenotype was seen, both between individuals and within the dentition of some individuals. Many of the adults had received extensive dental restorative work. These findings re-enforce previous observations of variable phenotype in this and other forms of the condition and add to the argument for a revision of methods of classification. This history of this large family draws further attention to the restorative demands of this group of dental anomalies and, by their generous co-operation, will prove an invaluable help in the investigation by molecular genetic techniques of this disfiguring condition.

Adolescent↗
PubMed1980

A new hominid fossil skull (L.H. 18) from the Ngaloba Beds, Laetoli, northern Tanzania.

In 1976, a fossil hominid skull was recovered from the Ngaloba Beds at Laetoli, Northern Tanzania; its morphology is discussed here. The discovery of this skull is of great interest and importance because of its very substantial presumed antiquity and its largely anatomically modern morphology. The discovery has considerable implications for the antiquity and origin of modern Homo sapiens, a subject of longstanding interest and one which has gained renewed attention recently.

Animals↗