Sten Linder-Aronson

Mandibular growth direction following adenoidectomy

The purpose of this article is to test the hypothesis that the establishment of nasal respiration in children with severe nasopharyngeal obstruction can be eliminated as a factor in determining mandibular growth direction. The article describes the changes in mandibular growth direction (MGD) in a 5-year period after adenoidectomies and the establishment of nasal breathing in a population of Swedish children. Measurements of mandibular growth directions were obtained from serial cephalometric radiographs after adenoidectomies in 38 Swedish children aged 7 to 12 years with previous nasopharyngeal obstructions. These were compared with the growth directions in a control sample of 37 Swedish children with clear airways and matched for age and sex. The adenoidectomy sample initially showed significantly longer lower face heights, steeper mandibular plane angles, and more retrognathic mandibles than the matched controls. Analysis showed that during the 5 years after adenoidectomies, the girls had a more horizontal MGD (P less than 0.02) than did the female controls. A corresponding but not significant trend was found for the boys. The individual growth directions that were obtained following adenoidectomies were more variable than those found in the controls.

Effects of adenoidectomy on dentition and nasopharynx

Abstract The purpose of the present study was to determine whether adenoidectomy (and hence a change to nose breathing) is followed by: (1) a change in the inclination of upper and lower incisors. (2) a change in the width of the upper arch, and/or (3) an effect on the sagittal depth of the bony nasopharynx. The clinical material comprised the children in a previous study who were at least 8 years old and in whom the upper and lower incisors had erupted before the initial examination, which was followed by adenoidectomy. A second examination was made 1 year later. The group undergoing adenoidectomy numbered thirty-seven children, and there were thirty-seven controls. All the children were examined with respect to forty-six variables, grouped under the headings of anamnesis, adenoids, dentition, airflow, and skeleton. Measurements were obtained for each child from lateral radiographs and casts, and the nasal airflow was recorded in liters per minute. Group means for the two examinations have been compared and relationships have been studied with the aid of simple correlation analysis and multiple regression analysis. It was found that in the year between the examinations, the children who underwent adenoidectomy had undergone a significantly greater increase than the controls in the angle of the upper and lower incisors, respectively, to the nasion-sella and the mandibular lines. The adenoidectomy group also had a significantly greater increase in the mean width of the upper arch between the first molars, this width being enlarged most in the children who had switched from mouth to nose breathing after adenoidectomy. Furthermore, the mean sagittal depth of the nasopharynx had increased only for the children who underwent adenoidectomy, the increment in this group being significantly different from 0. The study accordingly demonstrates that dentitional changes occur after adenoidectomy in children who were mouth breathers preoperatively because of nasal obstruction. The size of the nasopharyngeal cavity also changed in the children who switched from mouth to nose breathing after adenoidectomy. Since the dentition seems to be affected to some extent by the combined occurrence of adenoids and mouth breathing, an assessment of indications for adenoidectomy should include orthodontic evaluations.

Mandibular and maxillary growth after changed mode of breathing

The amount of maxillary and mandibular growth and the direction of maxillary growth were studied in 38 children during the 5 years after adenoidectomy for correction of severe nasopharyngeal obstruction. The amount of mandibular growth measured between successive gnathion points on superimposed radiographs was significantly greater in the group who had an adenoidectomy than in the matched controls. In the boys the difference was 3.8 mm (p less than 0.001), and in the girls the difference was 2.5 mm (p less than 0.01). The boys also showed a tendency toward greater growth in the maxilla as measured between successive subnasal points (1.2 mm, p less than 0.05). We detected no difference in the direction of maxillary growth between who had undergone adenoidectomy and the controls.

Cephalometric radiographs as a means of evaluating the capacity of the nasal and nasopharyngeal airway

Abstract The present investigation was carried out in an attempt to clarify the value of lateral skull and frontal radiographs as a means of evaluating nasal respiratory function. The study material consisted of 162 children between the ages of 6 and 12 years, with a sex distribution of 40 percent female and 60 percent male. The capacity of the nasal airway was both measured and subjectively evaluated, using lateral skull radiographs of twenty-eight children between the ages of 8 and 12 years without adenoid vegetations at the posterior nasopharyngeal wall. The size of the adenoids was measured and evaluated in a similar fashion. In addition, they were graded clinically by posterior rhinoscopy. The nasal airflow was measured according to a method previously described by Aschan and associates 1 and subsequently modified by Linder-Aronson. 7 In this way, simultaneous recordings of the airflow velocity and pressure gradient between the nasopharynx and nostrils were obtained. Subsequent correlation analyses gave the following results: 1. 1. A significant relationship between the size of the adenoids as measured on lateral skull radiographs and assessed clinically. 2. 2. A negative relationship between the size of the adenoids as measured on lateral skull radiographs and the nasal airflow. 3. 3. A significant relationship between the capacity of the nasal airway as measured on frontal radiographs and the nasal airflow. 4. 4. A reasonable assessment of the nasal airflow by subjective evaluation of airway capacity from frontal radiographs.

Normalization of incisor position after adenoidectomy

Changes in incisor inclination and position in both jaws of children during the first 5 years after adenoidectomy were studied. The main change is a significant increased labial inclination of the incisors for the adenoidectomy groups. All variables that measure the labiolingual position of the mandibular incisors confirm a significant labial incisor positioning for both sexes. Stepwise regression analysis shows that 41% to 44% of the incisor proclination after adenoidectomy is accounted for by two regressors--sex (female) and increase in the sagittal size of the nasopharynx. The study supports the hypothesis that a changed mode of breathing after adenoidectomy is associated with significant labial positioning of the incisor teeth.

Linkage Analysis of Candidate Regions in Swedish Nonsyndromic Cleft Lip with or without Cleft Palate Families

OBJECTIVE To analyze linkage of five candidate regions for nonsyndromic cleft lip with or without palate (CLP) on chromosome 2p13, 4q, 6p23, and 19q13; in addition chromosome 1q32, the locus for van der Woude syndrome, on Swedish CLP families. DESIGN Three to five linked microsatellite markers were selected from each candidate region. Polymerase chain reaction (PCR) with fluorescent-labeled microsatellite markers was performed on DNA samples from the participating families. Electrophoresis of the PCR products was performed on a laser-fluorescent DNA sequencer. The genotype data were analyzed with multipoint linkage analysis. Modes of inheritance tested included two autosomal dominant, an autosomal recessive, and a nonparametric model. Multipoint logarithm of odds (LOD) scores were also calculated by assuming genetic heterogeneity. PARTICIPANTS Nineteen Swedish multigenerational families with at least two first-degree relatives affected with CLP. Greater than 50% of the families studied show vertical transmission of the clefting phenotype and both inter- and intrafamilial variability were noted. RESULTS Cumulative multipoint LOD scores for the whole group of families calculated under autosomal dominant modes of inheritance were negative in all regions and less than -2 except chromosome 6p23. LOD scores calculated under recessive inheritance and the nonparametric model were inconclusive. There was no significant evidence of genetic heterogeneity among the sample group. CONCLUSIONS The group of Swedish CLP families did not demonstrate significant linkage to any of the five candidate regions examined. This might suggest a new but yet unknown CLP locus or loci in this family group. However, because linkage could not be excluded in some individual families, they should still be tested with candidate genes from these regions.

A morphometric study of bone surfaces and skin reactions after stimulation with static magnetic fields in rats

The present investigation was undertaken to measure any bone surface changes after stimulation with orthodontic magnets and, furthermore, to examine the soft tissue in immediate contact with the magnets. Both distal parts of the tibial hind legs in six groups of young rats were fitted with devices holding two orthodontic magnets in the experimental legs and similar devices without magnets in the control legs. The animals were killed after 2, 3, and 4 weeks. Morphometric evaluation showed significant increases in resorbing areas after 3 and 4 weeks. Similarly, a reduction was evident in the number of epithelial cells under the areas where the magnets had been applied. These findings indicate that the stimulation of bone resorption in the present study may have been caused by inhibition of the bone-lining osteoblasts. This proposition is supported by the apparent inhibitory effect of the magnetic fields on epithelial recycling that was seen as a reduced thickness of the epithelium under the magnets. Consequently, static magnetic fields should be used with care in orthodontic practice until a more complete understanding of their mechanism of action has been established.

The deciduous dentition after only primary surgical operations for clefts of the lip, jaw, and palate

Abstract The purpose of the present study was to investigate the occlusal status of the deciduous dentition in children with clefts of the lip, jaw, and palate for which only soft-tissue surgery has been performed without presurgical orthodontic treatment of the jaw or primary bone grafting. The material comprised forty children who underwent primary operations for congenital oral defects of various types at the Department of Plastic Surgery in Orebro during the period from 1964 to 1967. The patients were divided into five groups according to the nature of the clefts. Their mean age at the time of the examination was 4.9 years. No major anomalies in the deciduous dentition were found in the group with a soft-tissue cleft only (cheiloschisis). The highest incidence of malocclusion was found, as expected, among the children whose clefts involved bone. The incidence of cross-bite was relatively high (44 per cent) among the patients on whom primary surgical procedures were performed for correction of clefts in the hard and/or soft palate. Among the children with total clefts on only one side, a postnormal relation on that side was found in approximately 80 per cent, as compared with 25 per cent on the opposite side. Among these children the incidence of cross-bite on the side of the cleft was 75 per cent, and on the opposite side it was 25 per cent. Frontal inversion was observed in about 30 per cent of these children. These frequencies of cross-bite and frontal inversion among children with unilateral total clefts were in agreement with the findings of two previous studies of a similar nature. The incidences of cross-bite and frontal inversion were lower in the present study than in material where presurgical orthodontic treatment of the jaw and early bone grafting were undertaken in conjunction with the treatment of the oral cleft. The differences, however, are not statistically significant.

Clinical and genetic studies of Van der Woude syndrome in Sweden.

Van der Woude syndrome (VWS) is an autosomal dominant craniofacial disorder characterized by pits of the lower lip, hypodontia and cleft lip and/or cleft palate. It has been reported as the most common form of syndromic orofacial clefting with very high penetrance and varied expressivity. The disease locus for VWS has been mapped to chomosome 1q32, but the gene is yet to be cloned. Here we report a total of 11 Swedish VWS patients: 9 familial cases from two families and two isolated cases. Clinical examination of these patients showed phenotypic variability, even between patients from the same family. Genetic studies were performed using four microsatellite markers from chromosome 1q32. Constitutional deletion in this region was not demonstrated in any of the familial or isolated cases. However, in the two VWS families, linkage analysis using these markers showed positive LOD (logarithm of the odds) scores ranging from 2.56 to 2.88 to all individual markers. The highest LOD score of 3.75 was obtained with the combined haplotypes of D1S491 and D1S205, thus confirming linkage of VWS in these two families to 1q32. We conclude that there is varied expressivity but no evidence of genetic heterogeneity in VWS.

ORTHODONTIC APPLICATION OF COLOR IMAGE ADDITION TO VISUALIZE DIFFERENCES BETWEEN SEQUENTIAL RADIOGRAPHS

A new technique was developed making it possible to visualize changes that take place after premolar transplantation. Three sequential radiographs from a series of standardized control examinations were digitized and registered to the first radiograph in the series using subtraction technique. The digitized radiographs were then transformed into monochromatic images: red, blue, and green. After correction of gray level and contrast, the three radiographs were superimposed. All details that were common in the radiographs were then displayed in black-and-white. Details that were different appeared in color. Red and blue combines into magenta, blue and green into cyan, and green and red into yellow. A procedure was developed to create color-coded radiographs according to the above. The procedure was applied to cases that had been treated by premolar transplantation. The color coding offers the possibility to identify any radiographic changes that take place over time, eg, growth, apposition or resorption of bone, and progression or regression of pathological processes.