Biomedical subjects

C M Forsberg

Publications and source records attributed to C M Forsberg.

At least 19 recordsLinked to original sources

PubMed2000

Palatal growth and chemotherapy: effects of cyclophosphamide on bone formation in the intermaxillary suture in growing rats.

OBJECTIVE: To study the effect of cyclophosphamide (Cy) on bone formation in the maxillary median suture of young rats. STUDY DESIGN: Doses of 30 mg/kg body weight of Cy were administered to 12 experimental rats at 10 and 13 days of age. A corresponding amount of 0.9% sodium chloride was given to 6 control rats at the same ages. At 31 days, the median maxillary suture was studied histologically in the experimental and control rats. RESULTS: Structural changes of the osteogenic layers and cartilage components of the suture could be seen in the experimental rats. The thickness of the palatal bone was only 66% of that of the control rats, and the experimental rats also exhibited significantly reduced width of the suture. CONCLUSION: This study shows that Cy by itself can cause disturbances in bone formation in rats.

Animals↗

PubMed1998

A longitudinal laser fluorescence study of white spot lesions in orthodontic patients.

Orthodontic treatment with fixed appliances increases the caries risk in young persons. The aim of this study was to apply a new caries diagnostic method, quantitative laser fluorescence, for longitudinal in vivo quantification of changes in incipient enamel lesions related to fixed orthodontic appliances. Seven young patients with active caries lesions disclosed at removal of the orthodontic brackets and bands were enrolled in the study. Caries preventive measures were intensified, including dietary advice, oral hygiene instructions, and the regular use of a fluoride dentifrice. The caries lesions were monitored with the quantitative laser fluorescence method after removal of the brackets and once a month thereafter. For each lesion, three quantities were measured: lesion area (mm2), mean fluorescence loss (%) over the lesion, and maximum loss of fluorescence (%) in the lesion. During a 1-year follow-up period, the areas of the lesions decreased and the enamel fluorescence lost was partly regained indicating that a remineralization process had occurred. It was concluded that quantitative laser fluorescence seems suitable for in vivo monitoring of mineral changes in incipient enamel lesions, and useful for the evaluation of preventive measures in caries prone persons, such as orthodontic patients.

Adolescent↗

PubMed1998

Craniofacial morphology in Chinese and Swedish children with Angle Class I and Class II occlusal relations.

The purpose of this study was to compare the craniofacial morphology of a group of Chinese children from northern China with a group of Swedish children. Each ethnic group comprised 20 boys and 20 girls with Class I occlusion, and 20 boys and 20 girls with Class II occlusion. The ages of the children ranged from eight to ten years. Lateral cephalometric radiographs were used for the recording of a number of skeletal, dental, nasopharyngeal airway, and hyoid bone variables. The results of the comparisons of the two ethnic groups showed that the antero-posterior dimensions of the anterior cranial base and the maxilla in the Chinese children were significantly smaller than the corresponding dimensions in the Swedish children. The mean values of anterior and posterior face heights, inclination of the upper incisors, and protrusion of the lower incisors, were significantly greater in the Chinese than in the Swedish samples. In the median plane, the size of the nasopharyngeal airway was significantly greater in the Chinese than in the Swedes. This difference was due to the fact that the soft tissues covering the posterior nasopharyngeal wall were thinner in the Chinese children than in the Swedish children. In general, the ethnic differences were the same in the Class I and the Class II groups. The differences in some of the dental and skeletal characteristics found between northern Chinese and Caucasian-children are similar to previously described differences between southern Chinese and Caucasian children.

Asian People↗

PubMed1997

Long-term dental development in children after treatment for malignant disease.

A radiographic dental examination was performed in 16 children conditioned with total body irradiation (TBI) and cyclophosphamide (CY) prior to bone marrow transplantation (BMT), and in 52 children treated with multiagent chemotherapy. For each child, three age- and sex-matched healthy controls were selected. Evaluation of disturbances in dental development and tooth size was based on planimetric measurements of mandibular teeth on panoramic radiographs. Short V-shaped roots were diagnosed in 94 per cent of the children treated with TBI/CY compared with 19 per cent in the chemotherapy group (P < 0.001). Children receiving TBI/CY also exhibited a pronounced reduction in tooth size compared with the controls. Reductions varied from 19 per cent in incisors to 39 per cent in the second molars. In the chemotherapy group the corresponding values were 7 and 15 per cent respectively. When comparing crown/root ratios, the indices for incisors, canines (P < 0.05) and molars (P < 0.01) in the BMT group were significantly higher than the corresponding values in the control group. This indicates that the reduction in root size was more pronounced than the reduction in crown size. The premolars in the BMT group exhibited a similar reduction in crown and root size. All developing teeth were affected by multiagent chemotherapy and radiation therapy. The most severe disturbances were found in children treated with TBI/CY at a young age.

Age Factors↗

PubMed1997

A scanning electron microscopy study of disturbances in the developing rat molar induced by cyclophosphamide.

Scanning electron microscopy was used to study the effect of cyclophosphamide (Cy) on molar development in 18 Sprague-Dawley rats from 15 to 48 days of age after birth. Doses of 30 mg/kg body weight of Cy dissolved in 1 ml 0.9% NaCl were given to the rats at 10 and 13 days of age. Eighteen control rats had injections of 1 ml 0.9% NaCl at the same ages. The most obvious changes in the experimental teeth were found in the developing roots of the first and second molars and in both the crown and roots of the third molar. The roots of the first and second molars were short and showed apical closure in the experimental rats. In addition to the disturbances in crown and root formation, the third molars were also significantly reduced in total size as compared with the third molars in the control rats.

Alopecia↗

PubMed1996

Tissue response to space closure in monkeys: a comparison of orthodontic magnets and superelastic coil springs.

Interest in using magnets for generating orthodontic forces started with the widespread availability of rare earth magnetic alloys. In vivo studies have indicated that a static magnetic field and/or corrosion products from the magnetic materials may induce biological effects when in close contact with cells or tissues. In the clinical situation, orthodontic magnets are often situated some distance away from the gingiva and bone. Consequently, the previously observed biological effects may not be found in an experimental situation mimicking the clinical setting. Thus, the present experimental study was undertaken to test this hypothesis using commercially available cobalt-samarium magnets for orthodontic treatment in comparison to treatment with Sentalloy closed coil springs with respect to possible side effects on alveolar bone growth, gingival epithelial thickness as well as rate of space closure. Corrosion of the uncovered areas of the magnets was already evident after 6 weeks. No statistical differences were found between the magnet and coil spring specimens with respect to rate of space closure, bone formation or epithelial thickness. The only two variables that differed significantly between magnet and coil spring specimens was that there were more resorption and more tetracycline labelled osteocyte lacunae under the magnets. In conclusion, although some marginal statistical differences were found between the magnet and coil spring specimens with respect to cell and tissue reactions, the near lack of cell and tissue effects of the magnets in the present clinical experimental situation compared to previous studies in which the magnets were positioned in close contact with the tissue under study, indicate limited adverse clinical effects.

Alveolar Process↗

PubMed1994

Histologic changes in dental morphology induced by high dose chemotherapy and total body irradiation.

Disturbances in dental development were studied with the use of radiography and histology in a patient with acute lymphoblastic leukemia who was treated with induction chemotherapy at 2.3 years of age and bone marrow transplantation at 4.3 years of age. The follow-up 9.5 years after bone marrow transplantation showed evidence of short tapered roots, enamel hypoplasia, microdontia, and aplasia. A histologic examination of two extracted permanent teeth showed that the crown of the maxillary lateral incisor exhibited numerous incremental lines that corresponded closely to the treatment periods with cytotoxic drugs. The maxillary second premolar exhibited regularly spaced incremental lines in the enamel and dentine. A gross hypoplasia was seen in the cervical part of the crown corresponding to the time of administration of 10 Gy total body irradiation. The results indicate that chemotherapy mainly induces qualitative disturbances in dentine and enamel, whereas total body irradiation induces both qualitative and quantitative changes.

Abnormalities, Radiation-Induced↗

PubMed1994

Changes in craniofacial development induced by growth hormone therapy in children treated with bone marrow transplantation.

The effect of growth hormone (GH) treatment on craniofacial development was studied in nine children exhibiting low growth velocity after bone marrow transplantation (BMT). Comparisons were made with seven BMT children who had not received GH. Two groups of age- and sex-matched healthy children served as controls for the respective patient groups. After an average observation period of 3.5 years, the BMT children not treated with GH exhibited significantly reduced mandibular length and alveolar height (p < 0.01). The increase in mandibular length was only 30% of that found in healthy controls. Maxillary growth was less affected by BMT treatment. In the GH treated group, no significant differences were found in craniofacial growth increments compared with controls. Although exogenous GH therapy in this group of children did not induce a catch-up growth, it appears to have prevented further loss in growth potential.

Adolescent↗

PubMed1994

Craniomandibular dysfunction in children treated with total-body irradiation and bone marrow transplantation.

The prevalence of pain and dysfunction in the stomatognathic system was studied in a group of 19 long-term survivors after pediatric bone marrow transplantation (BMT), conditioned with total-body irradiation (TBI). Compared with the control group, the children and adolescents in the BMT group had a significantly reduced mouth opening capacity. A reduced translation movement of the condyles was diagnosed in 53% of children treated with TBI, compared with 5% in the control group. Signs of craniomandibular dysfunction were found in 84% of children in the BMT group, compared with 58% in the control group. Both irradiation and chemotherapy induce long-term alterations in connective and muscle tissues resulting in inflammation and eventually fibrosis. These changes in tissue homeostasis and concomitant growth retardation may lead to the observed malocclusion and reduced mobility of the temporomandibular joint, with subsequent muscle pain and headaches, which were found in this study.

Acute Disease↗

PubMed1993

Etiological and predisposing factors related to traumatic injuries to permanent teeth.

Etiological and predisposing factors related to traumatic injuries to permanent teeth were studied in an epidemiological material comprising 1610 children with 286 registered traumatic dental injuries. The results showed that (1) postnormal occlusion, (2) an overjet exceeding 4 mm, (3) short upper lip, (4) incompetent lips, and (5) mouth breathing were all factors which significantly increased susceptibility to traumatic dental injury. The average overjet in children with injuries limited to enamel fracture was 4.3 mm. In cases exhibiting more severe injuries (dentine fracture, pulp lesion, root fracture, exarticulation) the mean overjet was significantly greater, 5.0 mm. The most common causes for injury were 'falls and blows' which were recorded as etiological factors in 69.9% of the boys and in 86.7% of the girls. Dental injuries sustained during participation in sports were twice as common in boys (18.2%) as in girls (8.2%). The frequency of tooth injuries caused by traffic accidents was comparatively low, 9.7% in boys and 5.5% in girls.

Adolescent↗

PubMed1993

Quantitative evaluation of the soft tissue profile in the planning of orthognathic surgery.

The clinical application of a proportional soft tissue profile analysis based on natural head position is presented. The analysis provides data concerning the morphological basis of facial disharmony in individual cases. The use of this information during treatment planning and evaluation of treatment results after orthognathic surgery is demonstrated in four patients with severe deviation from midnormal profiles.

Adolescent↗

PubMed1993

Vertical forces developed by the jaw elevator muscles during unilateral maximal clenching and their distribution on teeth and condyles.

The activity of the jaw elevator muscles (EMG) was recorded during maximal clenching in ICP and unilaterally on 2nd and 1st molars, premolars, canines and central incisors in ten subjects with complete dentitions, normal occlusal relationships, and without signs and symptoms of craniomandibular disorders. The EMG activities were converted to relative muscle force. The distribution of this relative muscle force on teeth and condyles was then calculated by means of a three-dimensional mathematical model. The results suggest that the magnitude of the muscle force is strongly associated with the localization of the biting point. Thus the greatest muscle force is produced during clenching in the intercuspal position (100%). At unilateral clenching 75% of this ICP-force is reached during rubber pad clenching on 2nd molars, 85% during rubber pad clenching on 1st molars and 45% during clenching on incisors. The calculations of the mathematical model showed then that highest bite force should be produced on 2nd molars (55% of the muscle force produced in ICP-clenching) and lowest on incisors (20%). Highest condylar load should be found on non-biting side condyles (20% of the muscle force produced in ICP-clenching) and lowest on biting side condyles (0%).

Adult↗

PubMed1992

Salivary clearance of sugar before and after insertion of fixed orthodontic appliances.

This study was conducted for the purpose of establishing the possible influence of orthodontic therapy with fixed appliances on salivary clearance of sugar. Fifteen consecutive patients between the ages 12 and 17 years took part in the investigation. Unstimulated salivary flow rate, residual volume of saliva in the mouth after swallowing (RESID), and salivary clearance of sugar was determined on two occasions, before treatment commenced and after a minimum of 3 weeks of appliance wear. Analysis of the data showed that both RESID and salivary flow rate exhibited significantly increased levels during orthodontic therapy. The insertion of fixed appliances did not seem to have any effect on the rate of salivary clearance of sugar. It was assumed that this finding could be a consequence of the combined effects of the changes in salivary flow rate and RESID.

Adolescent↗

PubMed1992

A proportional analysis of the soft tissue facial profile in young adults with normal occlusion.

A proportional soft tissue profile analysis is presented, based on natural head position (NHP) and an extracranial vertical reference line through Porion. Twelve linear soft tissue variables and norms for 11 indices expressing vertical and horizontal soft tissue proportions of the face were obtained from lateral skull radiographs of 40 Swedish adults (20 males, and 20 females) with good occlusion. Sexual dimorphism, with larger dimensions in men than in women, was most pronounced in the vertical plane. With regard to facial soft tissue proportions, significant differences between men and women were found only for those indices which involved measurements of lower jaw prominence and facial height. The means and standard deviations for six indices in the female group were compared with corresponding data obtained from the Peck and Peck sample, which had been selected on esthetic grounds. The results showed a close match between the groups. The proportional soft tissue analysis is recommended for the treatment planning of patients scheduled for orthognathic surgery.

Adult↗

PubMed1992

Shear bond strength of ceramic brackets with chemical or mechanical retention.

The study was undertaken to measure and compare the shear bond strengths of a ceramic bracket with chemical retention, a ceramic bracket with a new type of textured base providing mechanical retention, and a metal bracket with foil-mesh base. The tests were performed on 51 extracted human premolars which were randomly divided into three equally large groups (n = 17)--one group for each type of bracket. After debonding, the site of failure was noted and the enamel surface inspected with scanning electron microscopy. The ceramic bracket with chemical retention exhibited significantly higher bond strength than the corresponding bracket with textured base. In comparison with the metal bracket significantly higher bond strengths were recorded for both types of ceramic brackets. The ceramic bracket with mechanical retention and the metal bracket were comparable as regards the site of bond failure. In some cases the chemical bond provided very high values of bond strength. Enamel failure were recorded in three teeth which had been bonded with this type of ceramic bracket.

Acid Etching, Dental↗

PubMed1992

Salmonella enteritidis and other Salmonella in laying hens and eggs from flocks with Salmonella in their environment.

Seven Canadian layer flocks with Salmonella enteritidis in their environment were investigated to determine the numbers of hens infected with S. enteritidis, the localization of S. enteritidis in organs of infected hens and the numbers of S. enteritidis-infected eggs produced by two affected flocks. By a microagglutination test (MAT) using S. pullorum antigens, these flocks had more seropositive hens (mean 51.9 +/- 16.9%) than two Salmonella-free flocks (mean 13.0 +/- 4.2%). Culture of tissues of 580 hens (433 seropositive) from the seven flocks detected 26 (4.5%) S. enteritidis-infected hens from two flocks. In one flock, 2/150 hens were infected with S. enteritidis phage type (PT) 8, which was confined to the ceca, and no Salmonella spp. were isolated from 2520 eggs (one day's lay). In the second flock, where 24/150 hens were infected with S. enteritidis PT13, extraintestinal infection was found in nine hens and involved the ovaries and/or oviduct in two hens. Salmonella enteritidis PT13 was isolated from one sample of egg contents and from one sample of cracked shells from among 14,040 eggs (one day's lay) from this flock. The overall prevalence of S. enteritidis-contaminated eggs from the two flocks with infected hens was less than 0.06%. Other Salmonella spp. isolated were S. heidelberg from 58 hens (10%), and S. hadar, S. mbandaka and S. typhimurium from one hen (0.2%) each. The MAT with antigens of S. pullorum had a sensitivity of 81% and a specificity of 24% for detecting S. enteritidis-infected hens.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗

PubMed1991

The prevalence of Salmonella enteritidis and other Salmonella spp. among Canadian registered commercial layer flocks.

A survey was conducted to estimate the prevalence of Salmonella enteritidis and other salmonellas among Canadian commercial egg producing flocks. Environmental (faecal and eggbelt) samples from 152 of 295 (52.9%) randomly selected flocks were contaminated with salmonellas. Thirty-five different salmonella serovars were isolated. Eggbelt samples were more often contaminated with salmonellas than faecal samples (25.7 v. 10.1%). The most prevalent serovars were S. heidelberg, S. infantis, S. hadar, and S. schwarzengrund; they were isolated from samples of 59/295 (20%), 18/295 (6.1%), 17/295 (5.8%), and 15/295 (5.1%) flocks, respectively. Feed samples of 21/295 (7.2%) flocks were contaminated with salmonellas. Salmonella enteritidis was isolated from the environmental samples of 8/295 (2.7%) flocks. Salmonella enteritidis phage type (PT) 8 was isolated from 5 flocks, PT 13a from 2 flocks, and PT 13 from 1 flock.

Animal Feed↗

PubMed1991

A comparison between estimated and registered natural head posture.

Using tracings of facial profiles, four observers made two independent, subjective estimations of natural head posture (NHP) in 28 adults. The results of these estimations were compared with recordings of NHP obtained through photographic registration of the same subjects. Only minor average differences (between 0 and 1.4 degrees) were found between the two methods. The differences between estimated and registered head posture found at the first and second observation, were positively correlated for both intra- and inter-observer registrations (r = 0.59-0.80 and r = 0.50-0.71, respectively). The inclination of the basion-nasion line was measured; first, in relation to the photographically registered horizontal line and, secondly, in relation to the horizontal line derived from the estimation of NHP. Both methods of measurement gave similar mean values and standard deviations. A panel comprising 18 persons was asked to compare the head orientations of two subjects in whom a marked difference between estimated and registered NHP had been recorded. In the majority of these comparisons, the profiles orientated according to the subjective estimation were judged to have a more 'natural posture' than those orientated by the photographic method. This unexpected finding is discussed.

Adult↗