Biomedical subjects

J G Norén

Publications and source records attributed to J G Norén.

At least 19 recordsLinked to original sources

PubMed2005

Scanning electron micrograph analysis of hypomineralized enamel in permanent first molars.

UNLABELLED: First molars with cream- to yellow-coloured demarcated opacities of the enamel, often in combination with severe loss of substance, are common in many child populations. The aetiology is obscure. AIM AND METHOD: The aim of this study was to study the ultrastructure of the enamel of 10 affected teeth by means of scanning electron microscopy (SEM) in order to gain a better understanding of the clinical appearance and treatment problems of this condition, and to find some clues to its aetiology. RESULTS: The basic enamel structure with enamel rods and interrod zones was found in porous parts of the enamel, as well as in normal parts, but the packing of the hydroxylapatite crystals seemed to be looser and less well organized in the porous parts. The border between normal and hypomineralized enamel was usually distinct, and followed the direction of the rods. The preserved basic structure indicates normal function of the ameloblasts during their secretion phase, but impaired function during their maturation stage. CONCLUSION: Considering the poor etch profile, it seems reasonable to recommend removal of all affected enamel surrounding the cavity, if possible, and to use a glass ionomer filling with its chemical bonding to tooth substrate, when restoring first molars with remaining affected enamel.

Dental Enamel↗

PubMed2002

Oral manifestations in 22q11 deletion syndrome.

OBJECTIVES: The aims of this study were to investigate and describe oral manifestations in 22q11 deletion syndrome, and to relate the findings to medical conditions. DESIGN: Cross-sectional. SAMPLE AND METHODS: Fifty-three consecutive patients from Sweden referred to the Sahlgrenska University Hospital during a 3-year period were included, median age 8 yrs (range 2-43; mean age 11.09). All but six patients were children 3-19-years-old. The patients were examined concerning oral mucosa, dental anomalies, dental caries, occlusal development, and eruption of the teeth. The clinical findings were compared to medical data and case history. RESULTS: Dental anomalies were registered in high numbers. Enamel hypoplasia was found in 16 patients. In 13 cases this was documented in primary teeth, of which 10 patients had symmetrical and chronological defects. Enamel hypomineralization was found in 23 patients and was equally common in both primary and permanent teeth. The use of computerized inductive analyses revealed that enamel hypoplasia was associated with medical conditions like preterm birth and congenital heart malformation while hypomineralization was associated with more diffuse conditions like frequent infections. Hypodontia was registered in seven patients, while eight had aberrant tooth shape, and nine patients presented delayed tooth eruption. The patients had an average of 4.6 carious or filled teeth and the oral health was assessed as impaired in 15 patients who had severe dental caries (5-18 carious teeth or multiple active incipient caries lesions). CONCLUSIONS: In 22q11 deletion syndrome the oral cavity is affected by anomalies in dental enamel, tooth shape, numbers of teeth, and eruption. Dental health problems due to caries are common. This is of special importance as patients with 22q11 deletion syndrome frequently present with congenital heart malformations and immunological problems.

Adolescent↗

PubMed2001

Etiologic factors influencing the prevalence of demarcated opacities in permanent first molars in a group of Swedish children.

The aim of this study was to determine possible etiological factors for a developmental enamel defect, i.e. demarcated opacities, affecting the permanent first molars. A questionnaire about possible etiological factors of enamel developmental defects was filled in by the parents of 8-yr-old children (n=516) prior to a dental examination of permanent teeth. Demarcated opacities of permanent first molars had been found in 18.4% of the children in a previous study of these children. Fifteen % had more than one tooth affected indicating systemic causation. Questions were asked about mother's health and medication during pregnancy, birth complications, health and medication of the child during the first 3 yr of life, breast-feeding, heredity, and fluoride supplements. The affected children, especially the boys, were reported to have had more health problems, in particular asthma (but only 4 cases), during the first year of life. Use of antibiotics was also more common among the affected children, but owing to a strong co-variance with health problems these factors could not be separated. Breast-feeding history was similar in children with and without enamel defects. The etiology of hypomineralized first molars is not yet fully understood, but based on the results of this retrospective study, health problems in infancy, especially respiratory diseases, seem to be involved.

Age Factors↗

PubMed2001

Knowledge-based system for structured examination, diagnosis and therapy in treatment of traumatised teeth.

Dental trauma in children and adolescents is a common problem, and the prevalence of these injuries has increased in the last 10-20 years. A dental injury should always be considered an emergency and, thus, be treated immediately to relieve pain, facilitate reduction of displaced teeth, reconstruct lost hard tissue, and improve prognosis. Rational therapy depends upon a correct diagnosis, which can be achieved with the aid of various examination techniques. It must be understood that an incomplete examination can lead to inaccurate diagnosis and less successful treatment. Good knowledge of traumatology and models of treatments can also reduce stress and anxiety for both the patient and the dental team. Knowledge-based Systems (KBS) are a practical implementation of Artificial Intelligence. In complex domains which humans find difficult to understand, KBS can assist in making decisions and can also add knowledge. The aim of this paper is to describe the structure of a knowledge-based system for structured examination, diagnosis and therapy for traumatised primary and permanent teeth. A commercially available program was used as developmental tool for the programming (XpertRule, Attar, London, UK). The paper presents a model for a computerised decision support system for traumatology.

Adolescent↗

PubMed2001

The prevalence of demarcated opacities in permanent first molars in a group of Swedish children.

The permanent teeth of 516 7- and 8-year-old Swedish children from a low-fluoride area were examined for developmental enamel defects. Special attention was paid to demarcated opacities in permanent first molars and permanent incisors (MIH). The examination was done in their schools, using a portable light, a mirror, and a probe. The modified DDE index of 1992 was used for recording the enamel defects, supplemented with a further classification into severe, moderate, and mild defects. Demarcated opacities in permanent first molars were present in 18.4% of the children. The mean number of hypomineralized teeth of the affected children was 3.2 (standard deviation, 1.8), of which 2.4 were first molars. Of the children 6.5% had severe defects, 5% had moderate defects, whereas 7% had only mildly hypomineralized teeth. In conclusion, hypomineralized first molars appeared to be common and require considerable treatment in the Swedish child population.

Child↗

PubMed2001

Analysis of caries status development in relation to socio-economic variables using a case-based system.

The aim of this study was to detect, using case-based reasoning (CBR) induction methods in time series analysis, how measurable socio-economical adjustments were related to the caries status development. The study concerned the year classes leaving the organised dental care for the time period 1987-95, and had received dental care at the Public Dental Service of Göteborg. The results, as presented by a caries incidence index, indicated that at least one socioeconomical factor, individuals seeking employment, was of importance for the caries status development, a factor with an increase of considerable proportions since 1990. The findings indicated that the other socio-economic variables used did not have the same importance for the caries status development. One feasible explanation is that these factors reflect more upon the social family situation than the economical. If the caries status reflects the social situation of the individual more than the economical, this argument will elucidate the reasoning. Using CBR for the analysis of relationships between oral disease and parameters possibly influencing health development has proven to be a valuable tool and complement to more traditional statistical methods. The analysis can make relationships explicit through the hierarchic knowledge trees and also show redundant information, attributes not appearing in the trees.

Adult↗

PubMed2000

Long-term prognosis of crown-fractured permanent incisors. The effect of stage of root development and associated luxation injury.

OBJECTIVES: The aim of the present study was to investigate pulp healing responses following crown fracture with and without pulp exposure as well as with and without associated luxation injury and in relation to stage of root development. PATIENT MATERIAL AND METHODS: The long-term prognosis was examined for 455 permanent teeth with crown fractures, 352 (246 with associated luxation injury) without pulpal involvement and 103 (69 with associated luxation injury) with pulp exposures. Initial treatment for all patients was provided by on-call oral surgeons at the emergency service, University Hospital (Rigshospitalet), Copenhagen. In fractures without pulpal involvement, dentin was covered by a hard-setting calcium hydroxide cement (Dycal), marginal enamel acid-etched (phosphoric acid gel), then covered with a temporary crown and bridge material. In the case of pulp exposure, pulp capping or partial pulpotomy was performed. Thereafter treatment was identical to the first group. Patients were then referred to their own dentist for resin composite restoration. RESULTS: Patients were monitored for normal pulp healing or healing complications for up to 17 years after injury (x = 2.3 years, range 0.2-17.0 years, SD + 2.7). Pulp healing was registered and classified into pulp survival with no radiographic change (PS), pulp canal obliteration (PCO) and pulp necrosis (PN). Healing was related to the following clinical factors: stage of root development at the time of injury, associated damage to the periodontium at time of injury (luxation) and time interval from injury until initial treatment. Crown fractures with or without pulp exposure and no concomitant luxation injury showed PS in 99%, PCO in 1% and PN in 0%. Crown fractures with concomitant luxation showed PS in 70%, PCO in 5% and PN in 25%. An associated damage to the periodontal ligament significantly increased the likelihood of pulp necrosis from 0% to 28% (P < 0.001) in teeth with only enamel and dentin exposure and from 0% to 14% (P < 0.001) in teeth with pulp exposure. CONCLUSIONS: In the case of concomitant luxation injuries, the stage of root development played an important role in the risk of pulp necrosis after crown fracture. However, the primary factor related to pulp healing events after crown fracture appears to be compromised pulp circulation due to concomitant luxation injuries.

Adolescent↗

PubMed2000

Enamel hypomineralization of permanent first molars: a morphological study and survey of possible aetiological factors.

OBJECTIVES: The aim of this study was to investigate the morphological appearance of severe hypomineralized enamel of permanent first molars by means of polarized light microscopy, and to estimate the possible time, severity and longevity of the insult. Furthermore, the aim was to survey some commonly implicated aetiological factors in order to gain knowledge about possible pathogenesis of the enamel disturbances which could be compared with future epidemiological studies. SAMPLE AND METHODS: Seventy-three teeth, which had been extracted due to severe hypomineralizations of the enamel, were collected and serially cut longitudinally in a bucco-lingual direction. The sections were examined in polarized light, dry and embedded in water. The children were also examined with respect to the demarcated opacities of other permanent teeth than those that were extracted. The parents were asked about their health during the mother's pregnancy, the time of gestation, birth weight and any complications. They were also asked about the child's health during the first 2 years of its life, the length of time of breast-feeding and also about fluoride supplements. RESULTS: The hypomineralized areas extended cervically from the cusps, comprising about half of the buccal and lingual sides. The cervical borders to normal enamel were well defined and mainly followed the lines of Hunter-Schreger. The hypomineralized zones were covered by thin well-mineralized enamel. The majority of the children had demarcated opacities of all their first molars and also of some permanent incisors. No obvious correlation to the anamnestic data could be found. CONCLUSIONS: The hypomineralized enamel in the investigated teeth demonstrated areas of porosity of varying degrees. The yellow/brown defects were more porous than the white-cream and extended through the whole enamel layer, while the white-cream opacities were situated in the inner parts of the enamel. There had probably been an interacting disturbance of short duration of systemic origin of the activity of the ameloblast during the first 2 years of the child's life, resulting in chronological dispersed hypomineralized demarcated opacities in the developing teeth.

Adolescent↗

PubMed1999

Morphology of dental enamel and dentine-enamel junction in osteogenesis imperfecta.

OBJECTIVES: The aim of this study was to examine the morphology of primary and permanent human enamel, and the dentine-enamel junction, in individuals with osteogenesis imperfecta (OI) type I, III and IV in undecalcified sections using polarized light microscopy, microradiography and scanning electron microscopy (SEM), and to relate the findings to the type of OI. SAMPLE AND METHODS: Extracted or exfoliated teeth from 15 patients representing the OI types I, III and IV (12 primary teeth from seven patients, and 11 permanent teeth from eight patients). Ten primary and nine permanent teeth from normal healthy patients served as controls. The teeth were serially cut longitudinally in a bucco-lingual direction and contact microradiographs were made. The sections were examined in polarized light. Sections of primary and permanent teeth were examined by means of SEM. RESULTS: This study shows that the permanent enamel from patients with OI exhibits few structural changes. No relationships were found between enamel morphology and the types of OI (I, III, IV). Primary enamel appeared to be slightly more irregularly mineralized, especially in cases with the additional diagnosis dentinogenesis imperfecta. The major findings were deviations in association with the dentine-enamel junction, and locally a lower degree of mineralization. CONCLUSIONS: The mesodermal disease OI might also be manifested in ectodermal enamel, probably because of suboptimal mesenchymal-ectodermal interactions during amelogenesis.

Dental Enamel↗

PubMed1999

Machine learning methods applied on dental fear and behavior management problems in children.

The etiologies of dental fear and dental behavior management problems in children were investigated in a database of information on 2,257 Swedish children 4-6 and 9-11 years old. The analyses were performed using computerized inductive techniques within the field of artificial intelligence. The database held information regarding dental fear levels and behavior management problems, which were defined as outcomes, i.e. dependent variables. The attributes, i.e. independent variables, included data on dental health and dental treatments, information about parental dental fear, general anxiety, socioeconomic variables, etc. The data contained both numerical and discrete variables. The analyses were performed using an inductive analysis program (XpertRule Analyser, Attar Software Ltd, Lancashire, UK) that presents the results in a hierarchic diagram called a knowledge tree. The importance of the different attributes is represented by their position in this diagram. The results show that inductive methods are well suited for analyzing multifactorial and complex relationships in large data sets, and are thus a useful complement to multivariate statistical techniques. The knowledge trees for the two outcomes, dental fear and behavior management problems, were very different from each other, suggesting that the two phenomena are not equivalent. Dental fear was found to be more related to non-dental variables, whereas dental behavior management problems seemed connected to dental variables.

Artificial Intelligence↗

PubMed1999

A time-series analysis of caries status among adolescents in relation to socioeconomic variables in Göteborg, Sweden.

The aim of this study was to detect, using time-series analysis methods, whether measurable socioeconomic adjustments for the time period 1986-96, as presented by caries index values, could be related to a new trend in caries status development for specific age groups leaving the free state-organized dental care system. In the study, Göteborg was divided into four districts. The study showed a favorable development in dental health for the 15-19 age group. However, the caries incidence index DSa (decayed approximal surfaces) values showed no or only negligible signs of lower mean values. During the study period, the study showed an unfavorable trend concerning the socioeconomic variables related to health care. However, the incongruity for the different districts between the trend results of the caries index values and the contemporaneous socioeconomic variable development indicated few signs of relationship. In relation to general discussions of environmental questions, the idea of sustainable development was discussed when applied to the field of dental care. The results of this study indicate that dental health, in times of major economic adjustments and lack of resources for health care for the 15-19 age group in Göteborg--as interpreted by the caries indices used is an example of sustainable dental health development.

Adolescent↗

PubMed1999

Discrimination of morphological findings in dentine from osteogenesis imperfecta patients using combinations of polarized light microscopy, microradiography and scanning electron microscopy.

OBJECTIVES: The aim of this study was to investigate the morphological appearance of dentine in teeth from individuals with osteogenesis imperfecta type I, III and IV using different histological techniques, and to correlate morphological findings to different types of osteogenesis imperfecta. SAMPLE AND METHODS: Extracted or exfoliated primary and permanent teeth were collected from 15 patients with the osteogenesis imperfecta diagnoses I, III or IV, with or without the additional diagnosis dentinogenesis imperfecta. Ground and decalcified sections were prepared from the teeth. Histo-morphological studies of the dentine were performed utilizing light and polarized light microscopy, microradiography and scanning electron microscopy. RESULTS: Characteristic findings were irregular tubules, remnants of capillary inclusions and obliterated pulps. All types of osteogenesis imperfecta exhibited similar types of dentine aberrations, but patients with type III or IV had a higher frequency of aberrations when compared to type I. CONCLUSIONS: The combination of either polarized light microscopy or micro-radiography, together with scanning electron microscopy, gave the most amount of morphological information from dentine samples. In addition, aberrations in dentine structure were more clearly observable. Light microscopy was not critical for the analyses.

Adolescent↗

PubMed1999

Evaluation of three years of dental care of adolescents in the Public Dental Service in west Sweden.

107 individuals, randomly selected from the County of Göteborg and Bohuslän, all born in 1970 were followed regarding the dental care received 1987-1989. The records of each individual from the actual time were collected and information on diagnosis and treatment measures was gathered. Radiographs from the actual time were studied by one of the authors. Sixty-two per cent of the adolescents had been examined and treated all 3 years. Six percent had not been seen at all. The sample was divided into three groups depending on the patient's DFSa value at the examination the first year. This classification appeared to correlate well with caries development in the following years. One-fourth of the sample was responsible for the major part of the non-attendance and late cancellations. The dental health of these subjects was below average, and non-attendance seemed to be a further risk factor. The preventive measures undertaken during the study appeared to correlate poorly with the actual situation of the patient and the presence or absence of potential risk factors.

Adolescent↗

PubMed1998

A secondary ion mass spectroscopic study of the elemental composition pattern in rat incisor dental enamel during different stages of ameloblast differentiation.

In most earlier studies on the elemental composition pattern of dental enamel, a picture is presented which describes a limited region. In this study, estimates of the incorporation of some critical elements into enamel were correlated with the differentiation stages of the ameloblasts through out the whole tooth. Elemental analyses of rat incisor dental enamel during the secretory, transitional and maturation phases were performed using two different modes of secondary ion mass spectrometry (SIMS). The results were presented as ion images and three-dimensional spatial resolution graphs. In the elemental images of 23Na, 26CN, 35Cl and 39K, counts were detected during the secretory and maturation phases of amelogenesis. Variations were interpreted as resulting from secretion of elements during the secretory phase and resorption during the maturation phase. In line scans the ion yield from enamel during different stages of differentiation of the ameloblasts was analysed. The elements investigated were 12C, 19F, 23Na, 31P, 39K and 77CaCl. As seen in the images, most elements exhibited a higher ion yield during the earlier stages of secretion, and lower yields during the maturation-phase resorption. Cl, together with P, increased during the phases of maturation. In the most apical portions of the teeth, corresponding to a presecretory phase, an inverse pattern was seen for most of the elements. If the surface yield was high at the onset of the secretory phase, the presecretory yields were lower, and vice versa.

Amelogenesis↗

PubMed1998

Aspects of teeth from archaelogic sites in Sweden and Denmark.

The purpose of this study was to examine ground sections of primary second molars and permanent first molars from the same jaws. Teeth from 11 individuals were collected from archaeologic sites in Sweden and Denmark. Longitudinal buccolingual sections were examined in a polarization light microscope and in a Philips scanning electron microscope (SEM). The seven teeth from Sweden appeared to have been subjected to environmental influences at their burial site, which had affected both the dentin and the enamel. The teeth from the Danish sites had a normal color, and no disintegration of the dentin was seen. The general morphologic appearance was normal in all primary and permanent teeth. The position of the neonatal line indicated a normal full-term gestational age. The observed accentuated incremental lines in both the primary and permanent enamel suggested periods of dietary changes, possibly related to periods of illness. SEM images of the surface area of the Swedish teeth showed an extremely porous enamel surface with severe changes in the prism structure as an effect of acid penetration. The Danish teeth did not show any marked changes in the enamel.

Acids↗

PubMed1998

Inductive analysis methods applied on questionnaires.

The am of this study was to evaluate subjective aspects from questionnaires dealing with dental trauma by applying different computerized inductive techniques within the field of artificial intelligence to questionnaires consisting of descriptive variables and of questions reflecting functional, personal, and social effects of patients' oral situation following dental trauma. As the methodology used is new to many readers in odontologic sciences, a detailed description of both the processes and the terminology is given. Utilizing a neural network as a first step in an analysis of data showed if relations existed in the training set, but the network could not make the relations explicit, so other methods, inductive methods, had to be applied. Inductive methods have the potential constructing rules from a set of examples. The rules combined with domain knowledge can reveal relations between the variables. It can be concluded that the usage of methods based on artificial intelligence can greatly improve explanatory value and make knowledge in databases explicit.

Algorithms↗

PubMed1998

Differences in co-variation of inorganic elements in the bulk and surface of human deciduous enamel: an induction analysis study.

This paper demonstrates a method for determination of co-variation between some inorganic elements in the bulk and surface areas of human tooth enamel. The technique is based on a computerised induction analysis of data obtained by secondary ion mass spectrometry (SIMS). When comparing the present data with an earlier study from our laboratory, it became evident that with only a moderate increase in the amount of data for the induction analysis, the results increased very considerably in reliability and precision. The patterns of co-variation between different elements differed between the bulk- and surface enamel. Only Mg expressed a similar pattern. In the bulk enamel the elements Na and P expressed a high degree of co-variation. Similarly, Mg and C expressed a high degree of co-variation. Mg was an element often found to co-vary with bulk enamel elements. In the enamel surface, F and Cl co-varied. In addition, Cl was an element often found to co-vary with other enamel surface elements.

Carbon↗

PubMed1997

A retrospective evaluation of traumatized permanent teeth.

The purpose of this retrospective study (15 years follow-up) was to evaluate the long-term results of treatment to injured teeth following acute trauma. A total of 198 patients with 488 injured teeth were available for analysis. Uncomplicated crown fractures were restored with composite restorations in 106 teeth. 19% of the restorations had been replaced more than 10 times and at the final examination approximately 25% were rated as unacceptable, i.e. needing clinical treatment. Fixed prosthetic therapy had been provided for 106 teeth and endodontic treatment had been provided in 114. Colour changes appearing at late stage suggested obliteration, necrosis or endodontically treated teeth. Anterior composite restorations have been considered acceptable as semi-permanent restorations in patients of early school age (7-15 years), and may have been an advance on what was possible previously, but results of this clinical study suggest that they still do have major shortcomings. There remains a need for a simple, conservative method of restoring aesthetics to fractured and discoloured anterior teeth for clinical use in young patients of late school age.

Acute Disease↗