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Biomedical subjects

J R Jakobsen

Publications and source records attributed to J R Jakobsen.

At least 19 recordsLinked to original sources
PubMed1992

Orthodontic risk factors for temporomandibular disorders (TMD). I: Premolar extractions.

Concern about claims that premolar extractions may put patients at risk for temporomandibular disorders (TMD) led to this study. We report first findings from a longitudinal study of orthodontic patients begun in 1983. By using the methods of Helkimo, we collected TMD data before initiation of orthodontic treatment, between 0 and 12 months after debanding, and 12 to 24 months after debanding. Analyses related Helkimo scores with premolar extractions in 65 patients for whom orthodontic treatment had been completed. Twenty-six patients were treated without premolar extractions, 25 had four premolars extracted, and 14 had two upper premolars extracted. Tests for significance of differences between mean Helkimo scores were conducted for the nonextraction group compared with the extraction groups, and between pretreatment and posttreatment Helkimo scores for each group. Results included: (1) no significant intergroup differences between mean pretreatment or posttreatment scores, and (2) small but statistically significant (p less than 0.05) differences (in the direction of improvement) between mean pretreatment and posttreatment scores for both the nonextraction group and for the four premolar extraction group.

Adult↗
PubMed1991

Profiling providers of orthodontic services in general dental practice.

This study was designed to ascertain whether general practitioners who provide some orthodontic treatment to a relatively large proportion of their patients tend to limit themselves to the treatment of simple cases while they continue to refer more difficult cases or whether a high volume of orthodontic treatment is linked to an expanded scope of treatment and fewer referrals. Data pertaining to volume, scope, and other correlates of orthodontic services in general practice were obtained through a survey of dentists currently in general practice in Iowa. Of 1159 questionnaires mailed out, 728 (62.8%) were returned. To determine how the values of recorded variables differ among the providers of high and low volumes of orthodontic services and to determine whether these differences are significant, chi 2 tests of independence were calculated. The results obtained were used to generate descriptive measures of the profiles of providers of a high volume of orthodontic services in general practice. These profiles indicated that providers of a high volume of orthodontic treatment (1) performed the same amount of limited orthodontic treatment as providers of a low volume of orthodontic treatment; (2) performed significantly more major orthodontic treatment; (3) used significantly more fixed appliances, functional appliances, and headgears, but not removable appliances; (4) took significantly more hours of continuing education in orthodontics; and (5) referred significantly fewer patients to orthodontic specialists. In view of the projected increase in the amount of orthodontics performed in general practice, these findings suggest that, in the future, relatively more major orthodontic treatment is likely to be provided by general practitioners.

Education, Dental, Continuing↗
PubMed1990

Validation of oral status indicators.

In planning programmes and developing policy, dental public health officials rely on epidemiological data in the form of composite measures such as the DMFT index. However, the DMFT is often not sufficiently sensitive to detect differences in oral health between population groups. Measures that selectively weight components of the DMFT may be better dental indicators. Sheiham, Maizels and Maizels (1987) suggested a functional measure (FM) that weights filled and sound teeth equally and a tissue health (T-health) measure that differentially weights decayed, filled, and sound teeth. For the present analysis, these indicators were divided by 28 to make their range 0 to 1. The modified indexes are called FMI and THI. Carpay et al. (1988) also suggested a dental health index (DHI) that scores a subset of teeth. Data from 797 participants in the 1980 Iowa Survey of Oral Health that included eight independent variables were used to perform stepwise regression on DMFT, FMI, THI, and DHI to assess how well the independent variables correlated with these four dental indicators. R-square values were 0.37 for FMI and 0.36 for THI, but only 0.19 for DHI and 0.12 for DMFT, suggesting that the FMI and THI were more sensitive as dental health indicators. In addition, calculations made on aggregate data published from three national surveys show that the FMI and THI can detect changes in oral health over time. Because the FMI and THI are as easy to measure and calculate as the DMFT, but appear to be more sensitive, they show promise as indicators of oral health status.

Adolescent↗
PubMed1989

Changes in the maxillary and mandibular tooth size-arch length relationship from early adolescence to early adulthood. A longitudinal study.

The purpose of this study was to determine the association between the changes in maxillary and mandibular tooth size-arch length discrepancies (TSALD) and various dentofacial variables for 18 male and 14 female subjects with normal occlusion. All subjects were participants in the Iowa Longitudinal Growth Study and records were evaluated at two stages of dental development: stage I, when the permanent second molars initially erupted into occlusion (X age = 13.3 years); and stage II, at early adulthood (X age = 26.0 years). The following sets of variables were evaluated: mesiodistal crown diameters of single and groups of permanent teeth, dental arch widths and lengths, curve of Spee, maxillary and mandibular anterior and total crowding or spacing, anterior tooth rotations, and various cephalometric dentofacial parameters. Student's t test were used to compare subjects with the most and least changes. Regression analyses also were used to assess the relationships between these parameters and the changes in the maxillary and mandibular tooth size-arch length relationship. The most consistent finding from the t test comparisons is the significantly greater reduction in the available arch length in the group with the most TSALD at early adulthood. No other variables were found to be consistently different in the comparisons between the two groups. The results of the regression analysis indicated that a number of dentofacial variables are associated with the changes in the maxillary and mandibular TSALD--for example, the mesiodistal diameter of different teeth and the changes in anterior and posterior facial heights. The clinical implications of the present findings are discussed.

Adolescent↗
PubMed1989

Bond strength comparison: a simplified indirect technique versus direct placement of brackets.

Two methods for orthodontic bonding were used to attach brackets to 48 incisor and 48 premolar extracted human teeth. Half of the sample teeth were bonded by means of a highly filled bis-GMA adhesive by a direct placement method. The remaining teeth were bonded with the same adhesive by an indirect method suggested by Thomas. Actual chairside bonding procedures were simulated with regard to the timing and manipulation of adhesives and attachments. Tensile and shear bond strengths are reported for each of the two methods of bracket attachment.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

Comparisons of mesiodistal and buccolingual crown dimensions of the permanent teeth in three populations from Egypt, Mexico, and the United States.

The purpose of this study is to examine the mesiodistal and buccolingual crown dimensions in three populations--57 subjects (35 boys and 22 girls) from Iowa City, Iowa; 54 subjects (30 boys and 24 girls) from Alexandria, Egypt; and 60 subjects (26 boys and 34 girls) from Chihuahua, Mexico. All subjects had normal Class I occlusion, with no history of orthodontic treatment. Comparisons of single teeth as well as sums of groups of teeth were performed between boys and girls within and between the two populations. The analysis of variance general linear models procedure was used for statistical comparisons. The findings from this investigation indicated that (1) differences between antimeres are of small magnitude and of no statistical significance; (2) all populations have significant differences in tooth dimensions between the sexes with boys having larger canines and first molars; (3) there is greater variation in the buccolingual than in the mesiodistal dimensions among the three populations; (4) there is a greater similarity in tooth dimensions among the boys from the three populations than among the girls, but the magnitude of these differences is considered to be of little clinical significance; and (5) standards for the buccolingual diameters were developed for the three populations. As a result, it was concluded that prediction equations used for space analysis in the mixed dentition to determine tooth size-arch length discrepancies in the Iowa population can also be used for persons from Egypt and from the northern part of the Mexican Republic, with some suggested modifications.

Adolescent↗
PubMed1989

Compensatory developmental interactions in the size of permanent teeth in three contemporary populations.

The purpose of this study was to determine whether developmental interactions exist between the mesio-distal diameters of the first and second developing teeth in each of two morphologic tooth classes. The interactions were evaluated for the maxillary and mandibular incisors and premolars. Measurements were obtained on the dentitions of three contemporary samples from Iowa, Egypt and Northern Mexico. The findings from this study indicate that developmental interactions are present in the mesio-distal diameters between the first and second developing teeth within the two morphologic tooth classes evaluated, namely incisors and premolars. In other words, the mesiodistal diameter of the first developing tooth significantly influences the size of the second developing tooth within the same morphologic class.

Adolescent↗
PubMed1988

Stability of the LeFort I one-piece maxillary osteotomy.

The purpose of this study was to determine retrospectively the stability of the LeFort I osteotomy after one-piece maxillary impaction and wire fixation. Cephalograms of 31 patients were evaluated before surgery, immediately after surgery, in fixation, and postfixation. All subjects had characteristics of excessive vertical maxillary growth. Descriptive statistics for the absolute and relative changes of the various linear and angular parameters were calculated for the different stages. The analysis of variance general linear models procedure was used to compare the repeated measures of the total sample. From the present findings, it was concluded that (1) after the initial surgical superior repositioning, the maxilla continued to move superiorly and most of the upward movement occurred during fixation, (2) the anterior part of the maxilla moved superiorly more than twice that of the posterior part of the maxilla, (3) maxillary superior dental movement exceeded maxillary superior skeletal movement, and (4) maxillary horizontal skeletal movement exceeded maxillary horizontal dental movement. The clinical significance of the findings are discussed.

Adolescent↗
PubMed1988

Changes in the molar relationship between the deciduous and permanent dentitions: a longitudinal study.

The purpose of this study was to describe the changes in the molar relationship from the deciduous dentition to the permanent dentition in 121 subjects from the Iowa Longitudinal Growth Study. In addition, an attempt was made to determine the association between the various dentofacial variables and the changes in the molar relationship in 55 persons (33 male and 22 female subjects) with normal occlusion. All subjects were evaluated at three stages of dental development: stage I, completion of the deciduous dentition (means age = 4.94 years); stage II, when permanent first molars initially erupt into occlusion (means age = 6.91 years); and stage III, at the completion of eruption of the permanent dentition excluding third molars (means age = 13.01 years). The following sets of variables were evaluated: molar relationship, mesiodistal crown diameters of single and groups of deciduous and permanent teeth, dental arch widths, arch lengths, and various cephalometric dentofacial variables. Correlation coefficients and regression analyses were used to assess the relationships between these measurements and the changes in the molar relationship from the deciduous to the permanent dentition. The findings indicate that of the 242 sides evaluated in the deciduous dentition, 61.6% developed into a Class I molar relationship, 34.3% into Class II, and 4.1% into Class III. Those sides that started with a distal step in the deciduous dentition proceeded to develop into a Class II molar relationship in the permanent dentition. Of the sides with a flush terminal plane relationship in the deciduous dentition, 56% progressed to a Class I molar relationship and 44% to Class II in the permanent dentition. The presence of a mesial step in the deciduous dentition indicates a greater probability for a Class I molar relationship and a lesser probability for a Class II molar relationship. In the 55 subjects who achieved normal occlusion, the magnitude of change in the molar relationship was 1.91 mm in male subjects and 1.64 mm in female subjects. On the average, these cases had a mesial step in the deciduous dentition of 0.8 mm in male subjects and 1.0 mm in female subjects. There was a favorable difference between the maxillary and mandibular leeway spaces of 1.3 mm in male subjects and 1.1 mm in female subjects. There was also a favorable decrease in the Wits appraisal of 1.2 mm in male subjects and 0.6 mm in female subjects.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Simultaneous cleft lip and palate repair: an experimental study in beagles.

This study was designed to test the hypothesis that simultaneous lip and palate repair results in more severe craniofacial growth aberrations than lip repair or palate repair performed separately. Seventy-six purebred beagles were divided into five groups. Two of these groups were controls (unoperated and unrepaired animals); the three remaining groups were experimental (in one group only the lip was repaired, in another only the palate was repaired, and in the last the lip and palate were repaired simultaneously). Cephalometric measurements were analyzed using univariate and multivariate statistical techniques. In multivariate analysis, stepwise multiple regression and discrimination were applied to precisely assess the effects of the various surgical procedures. The results of this study indicate that simultaneous lip and palate repair results in more severe craniofacial growth aberrations than lip repair or palate repair performed separately.

Animals↗
PubMed1986

Mesiodistal crown dimensions in Mexico and the United States.

Measurement of crown width of the teeth from first molar to first molar in population samples from Northern Mexico and North Central United States finds only small differences that would be of little importance in orthodontic diagnosis.

Adolescent↗
PubMed1986

Dentists who practice with spouses or relatives: a pilot study of practitioners in Iowa.

Of 130 practicing dentists in Iowa surveyed, 73, or 6% of the practicing dentists in that state, responded that they worked with a total of 108 relatives. Half of the relatives were the dentists' spouses. One to ten relatives worked in each office. Overall, the dentists were satisfied with the associations and expected them to continue. Most dentists had informally defined associations, and 10% had written contracts. Dentists named "office policy and organization" most often and "finances" least often as motives behind the associations and "personal growth" most often and "recognition" least often as a satisfaction with the association. The respondents suggested 567 ideas for other dentists considering such associations.

Dentists↗
PubMed1986

Cephalometric comparisons of individuals from India and Mexico with unoperated cleft lip and palate.

The purpose of the study is to determine whether the presence of unoperated clefts of the lip and alveolus or cleft lip and palate have similar effects on the dentofacial relationships of individuals with different racial backgrounds. Nineteen individuals from India and eighteen from Mexico with either unoperated unilateral cleft lip and alveolus or unilateral cleft lip and palate were examined cephalometrically and compared to matched normal individuals. The first step in the data analysis was to compare the normal subjects in the Indian and Mexican samples. Because many statistically significant differences were found between the normal groups, each measure for each patient with a cleft was expressed as a percentage of the mean value for the matched normal group. These relative values for the different measures were then entered into analyses of variance to compare the Indian and Mexican groups with clefts. Subgroups with cleft lip and alveolus were analyzed separately from subgroups with cleft lip and palate. Few group comparisons based on the relative measures were statistically significant, thus suggesting that there was a great similarity in the dentofacial relationships of unoperated individuals with the same cleft type. If the present results are further substantiated by future studies, these findings should enable investigators to pool data on unoperated individuals from various sources. Such an approach can lead to a better understanding of the differences between the various cleft types while eliminating the masking effect of surgical or orthodontic treatment.

Adolescent↗
PubMed1985

Dentofacial relationships in persons with unoperated clefts: comparisons between three cleft types.

A total of thirty persons with unoperated unilateral cleft lip and alveolus, unilateral cleft lip and palate, and bilateral cleft lip and palate were evaluated. The ages of these persons ranged from 7 to 50 years. Fifty parameters were measured on the cephalograms and the dental casts. Descriptive statistics for these parameters were calculated. The analysis of variance (general linear models procedure) was performed to compare the three cleft groups. Among the significant differences between the cleft groups was an increased steepness of the mandibular plane in persons with palatal clefts. In addition, the persons with bilateral cleft lip and palate had a significant reduction in maxillary intercanine width. A description of the different dentofacial relationships of the different cleft types was also presented. From the findings of the present and previous investigations, it could be surmised that there are differences in the dentofacial relationships of persons with different cleft types. These differences need to be recognized, since they can influence both our understanding of the effects of the surgical repair of the lip and/or palate and the orthodontic management of these cases. The present findings in this relatively limited group of persons indicates that there is still a need to examine in detail a larger number of persons with untreated clefts of the lip and/or palate and to compare them with surgically treated persons from the same population if possible.

Adolescent↗
PubMed1985

Longitudinal changes in three normal facial types.

The purpose of this study was to describe and compare the dentofacial relationships of three normal facial types (long, average, and short). Comparisons of the absolute and incremental changes between 5 years and 25.5 years of age were made both longitudinally and cross-sectionally. The subjects consisted of 20 males and 15 females for whom complete sets of data were available for the period of this study. All subjects had clinically acceptable occlusion and had not undergone previous orthodontic treatment. Descriptive statistics summarized the changes in 48 parameters, including that of height for males and females at 5, 10, 15, and 25.5 years of age. Longitudinal comparisons of the growth curves evaluated the curve profiles and curve magnitudes for the three facial types for both males and females. The analysis of variance was also used to compare the absolute and incremental changes at ages 5, 10, 15, and 25.5 years. The investigation resulted in the following findings. (1) Most persons (77%) have been categorized as having the same facial type at 5 and at 25.5 years of age. There is a strong tendency to maintain the original facial type with age. (2) Comparisons of the growth curves of the different parameters--with the exception of the incremental curves for MP:SN and Pog:NB in males--consistently demonstrated parallelism of the curves, regardless of the facial type. On the other hand, comparisons of curve magnitude indicated significant differences among the three facial types. (3) The persons within each facial type expressed a relatively large variation in the size and relationships of the various dentofacial structures. (4) Significant differences in the dentofacial parameters were present between males and females with the same facial type. The differences among facial types were not identical in males and females. (5) Longitudinal analysis of the data lends more consistent and, therefore, more meaningful results than cross-sectional comparisons when facial growth trends need to be evaluated. This is because growth changes are often subtle and of magnitudes not readily observed when the data are evaluated cross-sectionally. Standards that are age-, sex- and facial type-specific are presented.

Adolescent↗
PubMedDate not supplied

A comparison of medical histories reported by dental patients and their physicians.

This paper reports on the comparison of 104 patient-provided medical histories and those provided by the patients' physicians. Patient-provided histories were obtained using a written health questionnaire with verbal follow-up. At the level of specific medical conditions, patients and physicians agreed only about half of the time, whereas there was better agreement by systemic disease category (average agreement 77%). Both patients and physicians reported systemic conditions not reported by the other, indicating that neither patients nor physicians can be relied on as the sole source of medical history information. Whenever there is a complex medical history or uncertainty about the completeness of the patient's knowledge and reporting of their medical history, contacts with the patient's physician(s) are indicated.

Adult↗