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Biomedical subjects

L Peck

Publications and source records attributed to L Peck.

35 records · Page 2Linked to original sources
PubMed1993

Maxillary canine-first premolar transposition, associated dental anomalies and genetic basis.

Maxillary canine-first premolar (Mx.C.P1) transposition, an uncommon dental anomaly involving positional interchange of the two teeth, was studied using a sample of 43 subjects with the abnormality. Data were recorded on sidedness, sex, race, tooth agenesis, and peg-shaped maxillary lateral incisors for each case. Mx.C.P1 transposition occurred bilaterally in nearly one-quarter of the sample and favored female expression (sex ratio, M1:F3.8) and left-side occurrence (61% of unilateral cases). Familial occurrence was noted, as was a predilection for white subjects. Tooth agenesis (excluding third molars) and/or peg-shaped maxillary lateral incisors accompanied Mx.C.P1 transposition in 49% (21) of the subjects, four to ten times the normal rate of occurrence. Data from this study and the analysis of previously published cases provided strong evidence that Mx.C.P1 transposition is a disturbance of tooth order and eruptive position resulting from genetic influences within a multifactorial inheritance model.

Adolescent↗
PubMed1993

Comparison of dental arch dimensions in children from southern and northern Finland.

The purpose of this survey was to determine whether children in northern Finland had different dental arch dimensions from children in southern Finland. Dental casts of 9-year-old healthy children from Helsinki (southern Finland) and from Oulu and Sodankylä (northern Finland) were measured. Each group contained 41 subjects who had received no orthodontic treatment. The children from Sodankylä and Oulu had narrower dental arches and greater palatal heights than those from Helsinki. The lengths and perimeters of dental arches were significantly shorter in the children from Sodankylä than in those from Helsinki. We suggest these differences could have resulted from adaptation to different climatic conditions, affecting modes of breathing.

Cephalometry↗
PubMed1993

A time for change of tooth numbering systems.

Tooth numbering provides dentists with an essential shortcut in clinical record-keeping. Today, three systems are favored worldwide: the Zsigmondy/Palmer system, the universal system, and the FDI two-digit system. Histories of these tooth numbering methods are traced, and the strengths and deficiencies of each are discussed. The FDI two-digit system-used throughout the world, but not in the USA-is the only method that makes visual sense, cognitive sense, and computer sense. It deserves consideration by American dentists as our official tooth numbering system.

Dentition↗
PubMed1992

Some vertical lineaments of lip position.

This study was performed to elucidate quantitatively upper lip-tooth-jaw relativity in the vertical dimension. Values for five linear dentolabial measurements were generated from male (n = 42) and female (n = 46) reference samples. In addition, three vertical skeletofacial dimensions and two vertical dental dimensions were recorded. A significant sexual dimorphism was found in the vertical lip-tooth-jaw relationship: the upper lip of the female subjects was positioned on average 1.5 mm more superiorly at maximum smile than the upper lip of the male subjects (p less than 0.01). High smile lines appeared to be a female lineament, and low smile lines appeared to be a male lineament. There was a significant sex difference in upper lip length: the male subjects exhibited a longer upper lip than the female subjects (p less than 0.001). The mean difference was 2.2 mm. A similarly significant male-female difference was seen in the skeletal maxillary height measurement: the male sample showed a 2.2 mm mean vertical maxillary increase over the female sample (p less than 0.001). Furthermore, a significant difference was found between the clinical crown height of the maxillary central incisors in the male and female subjects of comparable ages: the male group had longer central incisor crowns (p less than 0.01).

Adolescent↗
PubMed1992

The gingival smile line.

A comparative study was performed to examine the nature of the gingival smile line (GSL), a specific dentolabial configuration characterized by the exposure of maxillary anterior gingiva during a full smile. Five soft-tissue, three dental and three skeletal variables were selected, measured and reported for a GSL sample (n = 27) and a reference sample (n = 88), both consisting of North American white orthodontic patients with a median age of 14.4 years. The results indicated that the capacity to project a gingival smile was related to: anterior vertical maxillary excess and the muscular ability to raise the upper lip significantly higher than average when smiling. Other variables significantly associated with GSL were greater overjet, greater interlabial gap at rest, and greater overbite. Factors that did not appear associated with the GSL phenomenon were upper-lip length, incisor clinical crown height, mandibular plane angle, and palatal plane angle. Clinical aspects of GSL were discussed.

Adolescent↗
PubMed1991

Skeletal asymmetry in esthetically pleasing faces.

An x-ray cephalographic method was used to analyze 52 exceptionally well-balanced white adult faces for skeletal asymmetry in the posteroanterior (PA) projection. Three frontal facial lines were constructed using bilateral skeletal landmarks: latero-superior orbit (LO), lateral zygoma (Zyg), and gonion (Go). All subjects demonstrated measurable asymmetries. Data showed less asymmetry and more dimensional stability as the cranium is approached. A slight tendency toward right-side dominance was not statistically significant.

Adolescent↗
PubMed1989

The period between exfoliation of primary teeth and the emergence of permanent successors.

The dates of natural exfoliation of primary teeth and of clinical eruption of their successors were recorded in 141 children, a total of 660 teeth. The aim of this investigation was to study the length of the period between these two developmental events. In the mandible, the mean length of the toothless period for the central incisor was 2 weeks and that for the lateral incisors and canines 6 weeks. In the maxilla, the corresponding period was 6 weeks for the central incisor and over 4 months for the lateral incisor and the canine. The mean length of the toothless period was shortest, 0-6 days, between the primary molars and the succeeding premolars. Individual variation was great. No difference was detected between the sexes. In some cases the length of the toothless period for the maxillary lateral incisors and for the canines in both jaws exceeded one year. This was associated with crowding, which caused the premature loss of primary teeth.

Child↗
PubMed1989

Caries-related microbiological findings in a group of teenagers and their parents.

The levels of salivary Streptococcus mutans and lactobacilli and caries experience were studied in 113 teenagers and 163 adults. The study population consisted of 82 mother-child and 73 father-child pairs. The number of decayed, missing, and filled tooth surfaces (DMFS) was eightfold higher in adults than in teenagers (56.4 +/- 22.8 vs. 7.3 +/- 6.7). The percentage distribution of the level of salivary S. mutans and lactobacilli was approximately the same in both groups. The mean number of DMFS increased with increasing levels of salivary S. mutans and lactobacilli, the correlation being highly significant both in teenagers and adults. There was a significant correlation of the DMFS indices in the mother-child pairs (r = 0.364), but the correlation was not significant in the father-child pairs (r = 0.138). The salivary level of S. mutans was higher in the children of mothers with high DMFS values compared to the children of mothers with low DMFS values.

Adolescent↗
PubMed1987

Signs and symptoms of craniomandibular disorders in a series of Finnish children.

The prevalences of subjective symptoms and clinical signs of craniomandibular (CM) disorders, orofacial parafunctions, and occlusal conditions were determined in a series of Finnish children (n = 166). All were first interviewed, and then 156 of them were examined clinically. Fifty-two per cent of the children reported at least one subjective symptom, and 75% at least one parafunctional habit. Clinical signs were common but rarely severe in accordance with Helkimo's clinical dysfunction index (Di). Both the number of subjective symptoms (p less than 0.001) and the number of orofacial parafunctions (p less than 0.05) correlated with the clinical dysfunction index.

Adolescent↗
PubMed1986

Dental maturity in Finnish children, estimated from the development of seven permanent mandibular teeth.

Overall dental maturity was studied semilongitudinally in a group of 248 healthy children born in Helsinki in 1968-73. In all, 738 orthopantomograms were taken of these children at ages of 2.5-16.5 years. Overall dental maturity was estimated by the method of Demirjian and Goldstein, which is based on the development of seven left mandibular permanent teeth. The aim of the study was to construct dental maturity curves for Finnish children and to compare their dental maturity with that of French-Canadian children studied by the same method. The Finnish children were more advanced in dental maturation than French-Canadian children (p less than 0.01). In boys the advancement was seen at the age of 5-10 years and in girls at the age of 4-12 years. These findings suggest differences in overall dental maturity among white population groups.

Adolescent↗
PubMed1979

Chemical modification of nuclear proteins by erythropoietin.

The spleen of the exhypoxic polycythemic mouse was employed as a model system to study the effect of erythropoietin on enzymes that chemically modify nuclear proteins. At selected time intervals after in vivo administration of erythropoietin, acetyltransferase and methyltransferase activity were measured in nuclei isolated from the spleens of treated mice. In addition, the incorporation of labeled methyl and acetate groups into individual histone proteins was also examined. A 36% increase in nuclear acetyltransferase activity was observed eight hours after administration of erythropoietin, whereas nuclear methyltransferase activity increased by 42% 24 hours after administration of the hormone. Selective acetylation or methylation of individual histone proteins was not observed, and it is concluded that activation of transcription by erythropoietin is not the result of acetylation or methylation of nuclear proteins.

Acetylation↗
PubMedDate not supplied

Mandibular lateral incisor-canine transposition in monozygotic twins.

Mandibular tooth transposition, involving the right lateral incisor and canine, is described in monozygotic twin girls. This report provides evidence suggesting that genetic factors influence the development of mandibular lateral incisor-canine (Mn.I2.C) transposition. Interceptive orthodontic treatment for children with this rare occlusal abnormality should be considered.

Child↗