Bhim Sen Savara

An analysis of permanent mesiodistal crown size.

Abstract This article refers to the mesiodistal size of the permanent teeth and presents an effective way of locating and analyzing crown-size discrepancies. The analysis proposed contributes to a more complete study of intraoral etiologic factors and a more precise diagnosis and prognosis of the dental problem. It has been illustrated that crown-size patterns differ greatly, even among good occlusions (Figs. 1 and 2). Common to both subjects are the small premolars and molars. Favorable crown-size discrepancies (Fig. 2) usually involve smaller teeth, particularly posterior teeth, which allow flexibility for the self-correction of minor anterior space deficiencies. In contrast, the remaining figures illustrate various crown-size discrepancies and the resulting malocclusions. Irregularities associated with the size disharmonies include (1) crowding of the mandibular incisors, (2) labial displacement of canines, (3) end-to-end premolar relationships, and (4) marked labial inclination of the anterior teeth. The effects on interdigitation of discrepant teeth must be differentiated from the effects of rotations and tipping of the teeth. Fig. 5 shows Class I molar and first premolar relationships; however, there is a tendency toward an end-to-end second premolar relationship because of mesial inclination of the maxillary second premolar. The complexity of interdigitation in orthodontic treatment is emphasized by the theoretical existence of more than 22,000 billion possible combinations of crown-size discrepancies (excluding the third molars).

Prediction of first molar occlusion

Abstract A longitudinal study of the deciduous terminal plane relationship and occlusion of the first permanent molars was carried out in fifty-four boys and sixty-four girls 4 1 2 to 14 years of age. Distributions of the deciduous terminal planes, initial occlusion of the first permanent molars, the degree of association between the two, and subsequent changes in the occlusion of the first permanent molars are described. A method of predicting the occlusion of the first molars is presented.

Factors that affect the alignment of the mandibular incisors: A longitudinal study

Abstract Measurements on lateral cephalograms and study casts at two stages of dental development were used to study the influence of different variables upon the alignment of the mandibular incisors. In Stage I the only permanent mandibular teeth clinically visible were the incisors and the first molars. In Stage II all permanent teeth anterior to the first molars were in occlusion. The study casts of 150 subjects were classified subjectively in both stages as having crowding or proper alignment of the incisors. According to the frequency of the groups (Table I), the probability that a subject without crowding in Stage I will not have crowding in Stage II is 82 per cent and the probability that a subject with crowding in Stage I will have crowding in Stage II is 89 per cent. The error when these criteria are used is approximately 15 per cent. The axial inclination of the permanent mandibular incisors relative to the inclination of the first molars and the size of the first molars are strongly related to the presence of crowding of the mandibular incisors. This article points out that incisor crowding is not merely a tooth-arch size discrepancy but a discrepancy among many variables.

Analysis of errors in cephalometric measurements of three-dimensional distances on the human mandible

Abstract Reliability (reproducibility) of measurements of five mandibular dimensions was analysed. Sixteen replicate determinations per mandibular dimension were made on cephalograms of ten boys 7 years of age by two trained locators (each independently making two tracings), and two measurers each making two separate measurements on every tracing; total sample of 160 distances per dimension was thus obtained. By analysis of variance technique (nested design), variability in distances observed was partitioned into four factors: between-and within-locators, and between-and within-measurers. Standard deviation component estimates for each factor showed amounts of contribution by each source. Landmark location variability was about 5 times that due to measurement. Comparison of within-system and among-child standard deviation component estimates showed within-system variabilities to be about 15 per cent to 37 per cent of among-child variabilities.

Dental Caries in Children One to Six Years of Age as Related to Socioeconomic Level, Food Habits, and Toothbrushing

URING 1951, we examined 650 children, 1 to 6 years of age, living in L/ Portland, Oregon, for dental caries experience. Children of this young age level could be reached only at different nurseries, kindergartens, and grade schools. The staffs at different nurseries revealed that some of the nurseries were partly financed by charitable organizations, and others were maintained privately by the fees paid by the parents. We surmised that this factor would select the children from two different socioeconomic levels. Studying the dental caries incidence of children, according to the nursery attended, revealed a significant difference.4 However, the method used for determining the socioeconomic status of parents from the characteristics of the nursery (whether receiving public or private support) was criticized by sociologists on the basis of being poor in distinguishing socioeconomic levels. It was recommended that greater accuracy in establishing socioeconomic status of parents would be obtained if a trained interviewer visited the home of each child and, using a standardized questionnaire, secured information from the parents. The present investigation was therefore planned to study the association of dental caries in children with the socioeconomic status of parents. The possibility of the differences in socioeconomic status of parents resulting in variation in the frequency of refined carbohydrate consumption and health education of children (brushing of teeth) was also considered and investigated in this study.

Norms of size and annual increments of five anatomical measures of the mandible in girls from 3 to 16 years of age

Abstract Mixed longitudinal sample was composed of fifty girls observed annually for a minimum of 6 years during childhood and adolescence. Data were derived from cephalograms; measurements were corrected for distortion and enlargement. Means and standard deviations of size and annual increments were computed at each age for ramus height, body length, maximum length, bigonial width and bicondylar width. Growth was greatest in depth (maximum length and body length), next in width (bicondylar width and bigonial width) and least in height (ramus height). The increment rate of mandibular growth decreased over the childhood period, then increased until the circumpuberal maximum was reached, and subsequently decreased. Circumpuberal increase was greater in maximum length, ramus height and bicondylar width, than in body length and bigonial width.

Variability of cephalometric landmarks used for face growth studies

Abstract The problems giving rise to variability due to location of some cephalometric landmarks used for face growth studies are discussed. Anatomic criteria for the location of these landmarks are suggested, so that variability due to location of landmarks can be minimized. The inter-individual variability among different persons and intra-individual variability due to age are demonstrated with the help of cephalograms of children 5, 10, and 15 years of age.

Arc Length of the Dental Arch Estimated by Multiple Regression

Determining the arc length of the dental arch from measurements of arch width and arch length is a procedure that is used in dentistry for epidemiological studies concerning tootharch size discrepancies, in growth studies concerning longitudinal changes, and in anthropology for ethnic studies. Methods to assess the arc length are abundant: determination of the length of a thread laid along the dental arches (LUNDSTR6M, Svensk Tandlak T 5:399-413, 1942); determination of the length of a line drawn with devices such as the dental pantograph (STANTON et al, J Dent Res 11:885-902, 1931) or the cubic craniophore (HAYASHI, Bull Tokyo Med Dent Univ 3:175-218, 1956); measurements with a caliper that involve subtraction of the amount of crowding, or addition of the amount of spacing or both, to the sum of the mesiodistal crown diameters; and determination of the length of curves obtained by mathematical functions such as exponential, logarithmic, elliptical, parabolic, hyperbolic, the Fourier series, polynomial, and the transcendental functions. Of these methods, the fitting of a curve described by a mathematical function gives the most accurate and reproducible representation of the size and shape of the dental arch. The fourth degree polynomial is among the easiest curves to fit and still adequately describe the dental arch (K. H. Lu, J Dent Res 43:780, 1964). Two requirements with this method are that the coordinates of the selected points on the dental arch are recorded accurately (SAVARA and SANIN, Amer J Phys Anthrop 30:315318, 1969) and that with the fitting of a fourth degree polynomial, a computer is used. This study determined the accuracy of estimating the arc length of the dental arch by regression on arch width and arch length. The sample consisted of 160 dental arches

The origin of trigeminal response components elicited by electrical stimulation of the tooth pulp of the cat

Abstract Field potentials were recorded in the trigeminal sensory complex in response to monopolar and bipolar stimulation of the tooth pulp to characterize the resultant activity of pulpal and extrapulpal origin. Monopolar and bipolar stimulation of pulpal elements resulted in identical responses. Using monopolar stimulation, cathodal thresholds were usually but not universally less than anodal thresholds. Spread of activity to include periodontal afferents occurred at intensities somewhat above that necessary for maximal pulp responses. No spread of activity was found either to gingival afferents using monopolar stimulation or to gingival or periodontal afferents using bipolar stimulation at any stimulus intensity.

Prediction of occlusion by measurements of the deciduous dentition

Abstract Dental characteristics of the deciduous dentitions of forty-eight children were used to predict the occlusion of the same children in the permanent dentition. The first portion of this study determined the most useful occlusal characteristics for prediction; the second portion tested the validity of the results on a different sample. The study casts of the deciduous and permanent dentitions of each person were classified as either acceptable occlusion or malocclusion, resulting in the following four groups: (1) acceptable in the deciduous and permanent dentitions; (2) malocclusion in the deciduous and permanent dentitions; (3) malocclusion in the deciduous dentition and acceptable in the permanent dentition; (4) acceptable in the deciduous dentition and malocclusion in the permanent dentition. Tooth size and arch width in the deciduous dentition were compared among the four groups. It was found that malocclusion in the deciduous and permanent dentitions tend to have narrower deciduous dental arches. Furthermore, acceptable occlusions in the deciduous and permanent dentitions tend to have smaller deciduous teeth. We hypothesized that the group with malocclusion in the deciduous and permanent dentitions contains the children with genetically determined malocclusion in the permanent dentition. Statistical procedures indicated that measurements of deciduous arch width and tooth size could be used to predict the occlusion in the permanent dentitions of 82 per cent of the sample. (Children grouped as follows: A, malocclusion in the deciduous and permanent dentitions; B, Groups 1, 3, and 4 mentioned above.) This finding suggested that if the sample was representative of the population, a large number of children who were going to have malocclusion resulting from tooth- and arch-size discrepancies could be identified from four measurements at as early as 3 or 4 years of age. The validity of this result was tested on a different sample of forty-nine children, and in 65.3 per cent of the children malocclusion or acceptable occlusion in the permanent dentition was predicted correctly. While the use of powerful statistical procedures resulted in findings statistically significant in both experiments, they were not sufficiently strong to be clinically valid.