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Biomedical subjects

J B Hoeksma

Publications and source records attributed to J B Hoeksma.

23 records · Page 2Linked to original sources
PubMed1991

Vertical facial growth: a longitudinal study from 7 to 14 years of age.

Multilevel analysis is used to describe the changes in vertical facial dimensions and their relationships in Dutch girls between 7 and 14 years of age. For the anterior face height (nasion-gnathion) and the posterior face height (sella-gonion) a fourth degree polynomial was fitted. The mandibular plane angle (sella nasion-gonion gnathion) could be described with a second degree polynomial. Low correlations were found between the growth parameters (intercept and age coefficient) of the anterior and posterior face height, which points to independent growth and development of the anterior and posterior face height. The individual length and growth velocity (at age 10.8) of the anterior face height and the mandibular plane angle showed substantial correlations. It was concluded that changes during growth with regard to the mandibular plane angle are more strongly related to the anterior than to the posterior face height.

Adolescent↗
PubMed1989

Emergence of the deciduous incisors in CLP children.

A longitudinal study of the time of emergence of the deciduous incisors was performed in Dutch cleft lip and/or palate (CLP) children (n = 52). A group of normal children (n = 62) served as control. Emergence dates were registered by the parents and checked regularly by one of the investigators. Mean emergence times of the deciduous upper incisors--including both the cleft-sided lateral in the distal segment and in the premaxilla--and lower incisors were studied. The lateral incisor on the cleft side situated in the distal segment was delayed 8 months in children with a cleft lip and alveolus and 13 months in cleft lip and palate children. The delay for the lateral incisor situated in the premaxilla increased by nearly 4 months in these children. The upper lateral incisors on the non-cleft side and in cleft palate children were not delayed as compared with normal children. The central lower incisors emerged one month earlier than normal when there was a palatal cleft. Presurgical orthopaedics used in these groups could have caused this acceleration. The central upper and lateral lower incisors showed no significant differences in mean emergence ages as compared with the control group, nor between the various cleft types. Sex differences were not found in any of the groups.

Age Factors↗
PubMed1988

Dental anomalies in patients with familial and sporadic cleft lip and palate.

Based on the frequency of occurrence of cleft lip and palate (CLP) in a family, a distinction has been made between familial and sporadic CLP. It was presumed that the genetic predisposition in familial CLP is high, while in sporadic CLP environmental factors play an important role. This study describes the possible relationship between the incidence of dental anomalies and the genetic predisposition of CLP in both the deciduous and permanent dentition. Dental anomalies were studied in 100 CLP patients and 38 control subjects. Neither the number of dental anomalies, nor the numbers of missing and supernumerary teeth differed significantly between familial and sporadic cases. A comparison between subjects with and without CLP showed a significant difference in the morphology of the dentition of the upper jaw. This difference was quantitative rather than qualitative. This study indicates a direct relationship between cleft formation and formation of the teeth, irrespective of the genetic predisposition and the severity of the cleft (i.e. uni- or bilateral).

Anodontia↗
PubMedDate not supplied

Tissue changes in the rabbit periodontal ligament during orthodontic tooth movement.

In this (semi) quantitative animal study the reaction of the periodontal ligament (PDL) to experimental tooth movement is described. To this end, rabbit first incisors were moved sideways with helical torsion springs for periods varying from 3-24 hours. The initial force of the springs was 50 gf. The histomorphology of the PDL was studied in 5 microns thick plastic sections. Comparison with control animals and animals wearing passive springs showed that tooth movement leads to an increased trauma in the PDL within only a few hours. This trauma is characterized by hyalinization, tears and ruptures in the fibres and blood vessels, and by the presence of extravascular erythrocytes and pyknosis. Tissue damage significantly increased with time. After 24 hours of tooth movement, the PDL fibers are compressed or stretched in 68% of the sections and the blood vessels in the PDL are compressed or stretched in 62% of the sections. Even in the controls, more than 15% of the sections displayed slightly stretched or compressed fibers, and about 10% showed slightly compressed or stretched blood vessels. This indicates that some damage is regularly present in a normally functioning PDL. Increases in the percentage of sections with blood vessel compression are found in all groups wearing passive springs, especially after 6 hours. A high concordancy in compression and tension patterns of blood vessels and fibers is present in 83% of the sections. Pyknotic cells are practically confined to areas with compressed PDL fibers in rabbits wearing active springs. Extravascular erythrocytes were found in sections with all types of fiber patterns. A significant majority of extravascular erythrocytes, however, was found in areas with compressed fibers.

Animals↗