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Biomedical subjects

M A Larmas

Publications and source records attributed to M A Larmas.

18 recordsLinked to original sources
PubMed2002

Applying modern survival analysis methods to longitudinal dental caries studies.

Before the 1960s, tooth-specific caries risk was reported to be highest at 2 to 4 years after eruption. We studied the tooth-specific caries risk in three contemporary age cohorts in Finland. All together, 4072 boys and girls were followed annually from age 6 to age 18+ years in three age cohorts born in the 1960s, 1970s, and 1980s. We used a survival model and Bayesian inferential methods in the statistical analyses to establish the secular changes during this period. The analysis was based on the caries risk in individual teeth as a function of tooth age instead of summary measures, such as DMFS values. Our first finding was a marked overall decrease of caries. Moreover, analyses of the 1960 and 1970 cohorts revealed that the risk in molar teeth was highest immediately after eruption; in the youngest cohort, however, the risks of individual teeth were so low that no such dependencies on tooth age could be established.

Adolescent↗
PubMed1998

Timing of first fillings in the primary dentition and permanent first molars of asthmatic children.

The aim of this study was to analyze the timing of first fillings posteruptively in a cohort comprising 51 asthmatic children receiving inhaled corticosteroids and living in three communities in Ostrobothnia, Finland. They had all been born in the 1980s and had had asthma check-ups in the local asthma policlinic. A group of 102 healthy age- and sex-matched children served as controls. A longitudinal survival analysis of the timing of the first filling in the primary teeth and first permanent molars was conducted retrospectively using data from the annual dental health records. The timing of the first fillings in permanent first molars showed no statistically significant differences between asthmatic and healthy children, but the filling increments in the primary molars were consistently higher in the asthmatic group; the difference for the upper first primary molars was, for instance, statistically significant (risk ratio = 2.565; 95% confidence interval = 1.333-4.935). More extractions because of caries were also performed on primary molars in the asthmatic children. The findings support the hypothesis that factors related to the asthmatic condition might increase the risk of caries. A longer surveillance time would be needed to evaluate the effect of asthma on the permanent dentition.

Administration, Inhalation↗
PubMed1997

Chronic metabolic alkalosis, sucrose diet and dentine formation in young rats.

As acid-base status has an effect on bone formation and remodelling, chronic metabolic alkalosis was induced in 3-week-old rats for 6 and 7 weeks with 0.25 mol/1 of NaHCO3 in their drinking water to determine whether it has any effect on dentinogenesis in the molars. One group of rats was fed a high-sucrose diet and the other two a standard diet. The control groups had the same diets but drank distilled water. All the rats were injected with tetracycline to mark the onset of dentine apposition. The alkalotic effect of the NaHCO3 drinking water was confirmed by blood gas analysis at the end of the experiment. After death, tetracycline-marked dentine apposition was measured from sagittally sectioned mandibular molars. Chronic metabolic alkalosis did not affect dentine apposition in the groups with the high-sucrose diet, nor in the groups with the standard diet at 6 weeks, but reduced it significantly in first and second molars in 7 weeks at rats on the standard diet. A high-sucrose diet alone caused a greater reduction in the amount of dentine. The general growth of the rats was not affected in any of the groups.

Alkalosis↗
PubMed1997

Effect of early restorations of permanent molars on filling increments of individual teeth.

OBJECTIVES: The purpose of this work was to analyse longitudinally whether the placement of restorations on permanent molar teeth immediately after their eruption results in (a cohort with) higher filling increments in all individual teeth thereafter. The patient documents of 937 subjects born either in 1970-1971 or in 1980-1981 were analysed. METHODS: The methods of survival analysis were employed. If any of the first permanent molar teeth had been restored in the course of tooth emergence, the person was assigned to the experimental group, and all the others were placed in the control group. Those in whom all the first permanent molar teeth had been restored at the time of emergence were compared with all the others. RESULTS: Early restoration of any permanent molar indicated higher filling increments in all the other molar teeth. The differences between the groups with regard to the first and second molar teeth were statistically highly significant (e.g. D.17 for the girls: log-rank chi 2 = 32.8, p = 0.0001 and Wilcoxon chi 2 = 28.7, p = 0.0001). The differences were greater among the girls than among the boys. Early restoration of the first permanent molar teeth did not indicate high filling increments in the incisors, canines or the smooth surfaces of any tooth. CONCLUSION: Fissure caries and smooth surface caries are different entities. The present method can be of help as an additional tool to help the clinician identify "risk" patients, in that an early restoration in any first molar is a powerful indicator of a risk of restorations in the other first molar teeth and also the second molar teeth.

Adolescent↗
PubMed1996

Effect of early or late eruption of permanent teeth on caries susceptibility.

OBJECTIVES: The aim of this study was to analyse the possible effect of early or late eruption of permanent teeth on the placement of first restorations on the different surfaces. The oral health records, of a total of 486 children born in 1970 and 1971 living in three rural communities in Finland, were analysed. METHODS: Caries susceptibility was determined indirectly by a new method. The study groups were defined as falling outside one standard deviation either side of the mean value for the timing of the eruption of first permanent molar teeth. RESULTS: No statistically significant differences in restoration increments between the early and late eruption cohorts were found at the end of the study period. For the occlusal surfaces of the first molar teeth, the restoration placement curves plateaued at about 60-70%, while for the second molar teeth, the plateaus occurred at 50-60% for both study cohorts. In girls with 'late eruption', the height of the post-eruptive step (i.e. the number of teeth filled on the year of their eruption) was higher (50-100%) compared to boys and girls with 'early eruption'. The difference was statistically significant. For example, for the occlusal surface of D. 36, the 95% confidence interval for the difference between proportions was 12-53%. CONCLUSION: No consistent effect of early or late eruption of permanent teeth was found on caries susceptibility measured post-eruptively by the placement rate of first restorations in a follow-up study of more than 10 years among Finnish children born in 1970-1971.

Adolescent↗
PubMed1996

Timing of first restorations before, during, and after a preventive xylitol trial.

An independent longitudinal retrospective analysis of the timing, number, and cost of tooth restorations was conducted for all subjects (n = 313) in the age cohort of a municipal health center, in which two consecutive field trials of up to 3 years on the caries-preventive effect of the use of xylitol chewing gum were conducted (Ylivieska study, 1982-85). A computer program calculated the post-eruptive timing of the first restorations on each permanent tooth surface, and survival analysis methods were applied before, during, and after the trials. The cost of restorations was then calculated. The total number of new restored surfaces was 4.0 per child in the xylitol group and 9.3 in the controls during the decade after onset of the trial. The number of restorations on the occlusal surfaces of the first molars leveled off at 40-50% in the xylitol group and at about 60-70% in the control group. Plateaus for the second molars were at 30-40% and 60-70%, respectively. The time lag for the first restorations was longer in the xylitol group for the proximal and other smooth surfaces. A marked difference in favor of the xylitol group was observed in the proximal surfaces of the upper incisors (for example, the mesial surface of the upper mesial incisor for girls: log-rank chi-square = 11.1, p < 0.001). The preventive effect was most pronounced in teeth that had erupted during the trial. This analysis indicated that participation of subjects in the xylitol chewing gum trials resulted in a significant reduction in the number of first restorations and hence in costs during the decade after the onset of gum use.

Adolescent↗
PubMed1995

Timing of first restorations in permanent teeth: a new system for oral health determination.

OBJECTIVES: A system of oral health determination in which times between eruption of teeth and first restorations because of caries is measured is applied in a retrospective analysis of oral health data relating to rural health centres in Finland. METHOD: The retrospective analysis was carried out using data relating to three health centres in different parts of Finland. The times between eruption and the placement of the first restorations in subjects up to 18 years of age were investigated. RESULTS: Between 10% and 25% of all permanent molar teeth were filled in the year of tooth emergence--the 'immediate posteruptive step'. A steadily increasing restoration placement rate--the 'ascending growth phase'--was observed after the 'posteruptive step'. The restoration rate was found to plateau 5-8 years after eruption--the 'retardation phase'. CONCLUSIONS: Restoration increment curves with longitudinal measurements are believed to be a sensitive indication of oral health at both individual and population levels.

Adolescent↗
PubMed1995

Leaving the pulp chamber open for drainage has no effect on the complications of root canal therapy.

In this retrospective study the effects of different kinds of emergency treatments on flare-ups and other complications were examined. A total of 197 teeth received emergency treatment after diagnosis at the beginning of the root canal therapy; in 103 the pulp chamber was left open for drainage of pus, 35 were treated with dexamethasone sodium phosphate, and 59 with various other medicaments, followed by routine root canal treatment. In all, 404 teeth received root canal treatment without emergency treatment. If symptoms occurred during treatment, flare-up was said to be present. If a periapical radiolucency was found, long-term calcium hydroxide treatment was used: no sign of periapical healing radiographically after 6 months was described as a complication. The percentage of teeth with no complications varied from 72.2% (dexamethasone) to 78.9% (other modification) and the results showed no differences between the groups in the teeth with no complications, flare-ups or other complications. The number of bacteria detected with Gram's staining was higher in the teeth which were left open. In conclusion, leaving the pulp chamber open for drainage had no effect on the incidence of flare-ups or other complications.

Acute Disease↗
PubMed1995

Timing of first fillings on different permanent tooth surfaces in Finnish schoolchildren.

The timing of the placement of first fillings because of caries on different permanent tooth surfaces was determined at three health centers in Finland. The 927 subjects analyzed were born either in 1970-71 o4 in 1980-81. Basically, two different types of filling placement site were identified: 1) fissures and pits and 2) proximal and smooth surfaces. In some fissures and pits a 'post-eruptive'--that is, fillings placed in the year of emergence--was observed. This step had decreased markedly in the cohort born in 1980-81. The curves plateaued (retardation phase) at 50-60% for the occlusal surfaces in first molars for the children born in 1970-71 and at 20-30% for the younger cohort. The time without any filling varied from 1 to 7 years on smooth surfaces, and some surfaces remained totally filling-free. The filling placement curves followed the pattern of caries attack and can thus be used as an indicator of dental health.

Adolescent↗
PubMed1994

Timing of eruption of permanent teeth: standard Finnish patient documents.

Current standards for the eruption of teeth are constructed mostly on the basis of cross-sectional data. The aim here was to analyze the suitability of the standard patient documents created for health center dental care purposes for the collection of longitudinal data on tooth emergence. Copies of the oral health records of the 911 children born in 1970 and 1971 and in 1980 and 1981 living in three rural communities in Finland were re-examined and analyzed using a specially compiled computer program. The means and standard deviations are in line with previous results. The sex difference in emergence timing ranged from 0.1 to 1.0 years for the various teeth. The emergence of the teeth of the second phase of the mixed dentition was later in the children living in an endemic fluoride area, this difference being statistically greater for the boys than for the girls (95% Cl for differences between means was used to evaluate statistical significance). A secular trend in the eruption of permanent teeth was found between 1970 and 1980. Patient documents are shown to be suitable for the collection of longitudinal data on dental emergence.

Adolescent↗
PubMed1993

Thermogravimetric studies on sound and carious human enamel and dentin as well as hydroxyapatite.

The present study was conducted to investigate the thermal behavior of human sound and carious enamel and dentin. The results were compared to those obtained for pure hydroxyapatite. The volatile decomposition products were identified by mass spectrometry. Solid decomposition products were analyzed by infrared (IR) spectrometry. For both normal and carious enamel, the differential thermogravimetry (DTG) curves revealed three peaks at about 90-100, 330, and 900 degrees C. Both normal and carious dentin revealed two common peaks in their DTG curves, at about 90-100 degrees C and 330 degrees C. An additional peak at 500-600 degrees C was observed in the DTG curve of carious dentin in air atmosphere. This peak completely disappeared in nitrogen (N2) atmosphere. About 11-12% of sound and carious enamel was volatilized in air. The values for sound dentin were 34% and for carious dentin 54% per weight, respectively. Enamel and dentin (apatite protein complex) decomposed at higher temperatures than pure hydroxyapatite in air. In N2 atmosphere, both enamel and dentin are more resistant to thermal decomposition than in air, because organic materials decompose easier in an oxidizing atmosphere than in an inert atmosphere.

Adolescent↗
PubMed1991

Mineral content of different areas of human dentin in hypophosphataemic vitamin D-resistant rickets.

Calcium, phosphorus, fluoride, sodium, magnesium and zinc estimations were carried out on teeth from a patient with hypophosphataemic vitamin D-resistant rickets (HVDRR) and from a patient with acquired rickets with the aim of determining differences in the composition of dentine in these two types of rickets. Normal deciduous teeth served as controls. Mineral analyses were carried out using an electron probe micro-analyser after carefully polishing the hemisected specimens. After the analyses the specimens were coated with gold-palladium for more detailed SEM studies. The Ca, P, F and Zn contents of the calcospherites were normal, while there was more Na and less Mg in the dentine of HVDRR teeth than of controls. The significance of this remains unexplained. The mineral content of the interglobular spaces was very limited, but there was more Zn in these than in other parts of the HVDRR teeth, in the acquired rickets teeth or in the control teeth. The excess of Zn in the interglobular spaces is thought to have an effect on the mineralisation process in HVDRR teeth. The globular nature of HVDRR teeth is thought to be genetically controlled and the result of a reduction in the number of calcification nuclei. The globular nature of the HVDRR teeth was not due to lack of Ca and P, as the serum levels of these minerals were maintained within normal limits during tooth development by controlled phosphate supplementation. Because in acquired rickets the globules were seen at the developmental stage that the teeth had reached when the nutritional disturbance occurred, the fault in mineralisation is thought to be different from that in HVDRR teeth.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium↗
PubMed1990

Caries incidence in children with acyanotic congenital heart diseases before and after the heart operation.

An acyanotic cardiac disease (ASD) was diagnosed in a 9-year-old girl with a very high caries incidence and premature tooth eruption. After the heart operation her caries incidence declined considerably. An epidemiological survey was then conducted to find out if these observations could be generalized. dmf-t, dmfs, DMF-T and DMFS values for each year were counted retrospectively for a group of acyanotic heart diseased children operated on at the age of 5-7 years (mean 6) and another group operated on at the age of 10-13 years (mean 12), from the documents relating to annual examinations conducted by the public health dental services. The results were compared to those of healthy children matched for age and sex living in the same area. Heart disease resulted in DMF-T values above the control level in the group operated on at age 6 years, whereas the values were lower than the controls in the group operated on at age 12 years, the difference being significant after the operation in the latter case. It is concluded that acyanotic congenital heart disease may lead to a higher caries prevalence and sometimes rampant caries. When the caries prevalence of the population is high, however, (DMF-T higher than 4.5 at 12 years), the effect of heart disease remains hidden.

Child↗
PubMed1988

Dental status of adults with and without periodontitis.

All 30- to 59-year old subjects (N = 757) from a representative sample of adult Finns (total sample = 1,105), showing advanced periodontitis (marginal bone loss more than 30%, n = 125), were compared with their age- and sex-matched pairs showing no marginal bone loss (n = 291) with respect to the number of intact teeth (no caries experience) present. Both male (n = 83) and female (n = 42) subjects with advanced periodontitis had more intact teeth and intact molars than their matched pairs (113 men and 178 women) (P less than or equal to 0.01 for intact teeth and P less than or equal to 0.05 for intact molars in both groups). The total number of teeth present did not differ significantly between the compared groups. Contrary to earlier hypotheses, our results suggest that periodontitis and dental caries do not necessarily share a common etiology.

Adult↗
PubMed1986

Caries and fillings in the permanent dentition of cohorts of schoolchildren in Espoo, Finland.

The purpose of the study was to analyze longitudinally the timing of enamel caries and, thereafter, fillings in occlusal, proximal and smooth surfaces of the permanent dentition of cohorts of schoolchildren initially 7, 10, 13, and 15 yr old. Altogether 228 children were examined annually during a 3-year period. Enamel and dentin caries affected on an average less than 15% of the occlusal surfaces in the first molars and at most 4% of the premolars; fillings proved to be the main determinant of the DF-scores for occlusal surfaces. On the other hand, decay was the main determinant of DF-scores on the proximal surfaces of the molars for at least 6 yr after eruption. The results indicate that in the 1970s some overtreatment of occlusal caries may have occurred, whereas indications for fillings on proximal surfaces were more accurate. The reduction in the number of extractions and fillings during the late 1970s resulted in a considerable decrease in the DMF scores. The decrease on DMF scores appears to have been due only to a minor extent to the decrease in caries. Thus, there was a decline in DMF scores rather than a decline in the prevalence of caries during this period.

Adolescent↗