Factors contributing to mandibular anterior crowding in the early mixed dentition

The aim of this study was to uncover the possible factors contributing to mandibular anterior crowding in the early mixed dentition. Mandibular dental casts of 60 children in the early mixed dentition were divided into two groups according to the severity of mandibular anterior crowding. The space available for the mandibular permanent incisors, total incisor width, deciduous intercanine width, deciduous intermolar widths, permanent intermolar width, interalveolar width, and total arch length were compared between the crowded group (CG) and noncrowded group (NCG), and correlations with crowding were investigated. The mandibular deciduous intercanine width, mandibular deciduous intermolar widths, mandibular permanent intermolar width, mandibular interalveolar width, space available for the mandibular permanent incisors, and total arch length were significantly larger in the NCG. The total width of the four mandibular incisors did not differ significantly between CG and NCG. Significant inverse correlations were found between crowding and available space, deciduous intercanine width, deciduous intermolar widths, permanent intermolar width, and interalveolar width. Total incisor width was directly correlated with crowding. No significant correlation was found between crowding and total arch length. The results of this study suggested that individual variations play an important role in treatment planning. However, one must not overlook arch length discrepancies and transverse discrepancies in patients with mandibular anterior crowding.     

Tooth size-arch length relationships in the deciduous dentition: a comparison between contemporary and historical samples

In a recent study, it was reported that maxillary and mandibular arch lengths were significantly shorter in a sample of contemporary children in the deciduous dentition compared with a historical sample from about 50 years earlier. The purpose of this study was to describe secular changes that might have occurred in tooth sizes and tooth size-arch length relationships in the same cohorts of contemporary and historical North American white children in the deciduous dentition. The 2 samples were similar in terms of geographic location, racial and ethnic backgrounds, and socioeconomic status. Both samples were restricted to white children with a normal overjet (<4 mm) and a normal anteroposterior molar relationship, no anterior open bite, and no crossbite. In addition, subjects were excluded if any permanent teeth were erupted. Measurements of mesiodistal tooth sizes and arch lengths of maxillary and mandibular arches were made, and tooth size-arch length discrepancies (TSALD) were determined. The results indicated that tooth sizes were generally similar in the 2 cohorts but slightly larger in contemporary children. Crowding, as measured by TSALD, was found to be common in the mandibular arch for contemporary children in the deciduous dentition of both boys and girls. Moreover, crowding was much more common and severe in contemporary children compared with children in the historical cohort. Further research is needed to determine whether the increase in mandibular crowding in the deciduous dentition will continue to be observed in the mixed and permanent dentitions and to further establish these possible secular trends.     

The effects of early headgear treatment on dental arches and craniofacial morphology: a report of a 2 year randomized study

The aim of the present study was to determine the effects of early headgear treatment on dental arches and craniofacial morphology in children in the early mixed dentition. The total study group comprised 68 children of both sexes (40 boys and 28 girls) aged 7.6 years [standard deviation (SD) 0.3]. The children, who had a Class II tendency in occlusion and moderate crowding of the dental arches, were randomly divided into two groups of equal size, matched according to gender. In the headgear (HG) group, treatment was initiated immediately. The mean treatment time was 16 months. In the second group, which served as the control, only interceptive procedures were performed during the follow-up period. The records, which included dental casts and lateral cephalograms, were obtained after follow-up periods of 1 and 2 years. The lengths and the widths of the maxillary and mandibular dental arches were significantly increased in the HG group after the 2 year follow-up period. The mean increase in lower arch length and width was 2.4 mm (SD 1.7) and 2.2 mm (SD 1.2), respectively. On average, the space gain in the lower arch was half that of the upper arch. No significant changes were found in the arch dimensions of the control group. Maxillary growth restraint and labial tilting of the incisors were the most significant cephalometric findings in the HG group when compared with the controls. The use of headgear in the early mixed dentition is effective in the treatment of moderate crowding. It is noteworthy that significant space gain in the dimensions of the lower arch can be achieved by headgear application to the upper first molars.     

Difference in dental lateral arch length between 9-year-olds born in the 1960s and the 1980s

This study was carried out in two cohorts of 9-year-olds, born in the 1960s and the 1980s in Sweden and Norway, to test the hypothesis that there has been a change in the lateral arch space conditions of the dentition during the last decades. In Norway, 61 children born in 1963 and 58 children born in 1983 were examined. In Sweden, 66 children born in 1961 and 67 children born in 1984 were examined. Children with a prolonged sucking habit, major dentofacial anomalies, history of orthodontic treatment, and ancestors of foreign origin were excluded to avoid influence of these factors on the development of the dentition. Linear measurements were performed between the mesial surface of the first permanent molars and the distal surface of the permanent lateral incisors in the maxillary and mandibular dental arches with use of a sliding caliper. The results showed that the children born in the 1980s had significantly larger lateral arch spaces in the maxillary dental arch (P <.05) and in the mandibular dental arch (P <.01) than did the children born in the 1960s. The amount of tissue loss in the second deciduous molars (the teeth having caries lesions or having been extracted) was greater in the 1960s groups than in the 1980s groups (P <.001). Thus, the hypothesis, that there has been a change in the lateral arch space conditions during the last decades, was confirmed. The most obvious reason is the decline in caries prevalence that has occurred in the same period; thus, there has been less loss of proximal tooth material of posterior teeth.     

Spacing in the human deciduous dentition in relation to tooth size and dental arch size

Dental casts of 243 preschool children, 129 males and 114 females, aged 2.5-5.5 years, were analysed for the presence of interdental spaces, mesiodistal crown diameters, intercanine width, intermolar width and arch length (circumference). The prevalence of primate spaces (diastemata mesial to the upper canines and distal to the lowers) varied from 65 to 90% by arch and sex; it was lowest in the lower arch especially in females, and highest in the upper. These prevalences did not increase with age; however, other spaces which usually occur between incisors may develop towards the end of the deciduous dentition, commonly in arches with primate spaces. Generally, spacing of the deciduous anterior teeth was significantly related to mesiodistal crown diameter and intercanine arch width. The crowns were significantly broader and the arches significantly narrower in cases with no spaces than in those where spaces existed. As the genetic programming for tooth size also normally affects arch size, greater discrepancies between mesiodistal crown diameters of the deciduous anterior teeth and their permanent successors are probably associated with more deciduous arch spacing.     

Indicators of mandibular dental crowding in the mixed dentition

PURPOSE: Dental crowding occurring in the anterior part of the mandible in the early mixed dentition has been a subject of increasing concern for child patients, their parents, and the pediatric dentist. The aim of this study was to evaluate indicators of crowding found at the primary dentition, which may lead to the future manifestation of crowding at the anterior part of the mandibular arch in the early mixed dentition. METHODS: Skeletal and dental morphological characteristics at the stage of primary dentition were compared between two groups, using dental casts and cephalograms of 23 subjects. These two groups had been formed by evaluating the degree of crowding at 9 years of age (12 normal and 11 crowded cases). RESULTS: The size of several teeth in the crowding group was significantly greater than that found in the normal group. For the cephalometric measurements, a statistically significant difference was found only in the cranial base dimension (S-SE). The stepwise discriminant analysis showed that the mesiodistal size of the maxillary primary canine, the maxillary and mandibular dental arch lengths, and the posterior cranial base length (S-Ba) were effective discriminators in separating the two groups. CONCLUSIONS: It is concluded that larger primary tooth size is the chief indicator in the development of dental crowding. However, the maxillary and mandibular dental arch lengths and the cranial base dimensions, especially that of the posterior cranial base length in the primary dentition, should also be considered as indicators when attempting to predict dental crowding in the early mixed dentition.     

Anomalies of deciduous teeth and findings in permanent dentition]

Prevalence of anomalies of deciduous teeth has been analyzed in the general population of Zagreb preschool children. The sample comprised 2,987 children from 3 to 6 years of age (1,582 boys and 1,405 girls). Hypodontia was found in 0.47%, hyperdontia in 0.10%, and double teeth in 0.43% of total sample. Total prevalence of all anomalies in the sample was 1.0%. The sample for the analysis of permanent dentition has been enlarged with the clinical sample of children having the same anomalies and comprised 48 children. In all children with anomalies of primary teeth the orthopantomograms were taken and the status of permanent dentition was analyzed. In children with hypodontia in primary dentition hypodontia of permanent teeth was found in 100% of cases. Patients with hyperdontia of primary teeth displayed anomalies in permanent dentition in 85.7%, while in children with primary double teeth, anomalies of permanent teeth were present in 61.1% of cases. Missing deciduous teeth were found in both jaws in only 8.7% of cases, and in 34.8% in permanent dentition. Symmetrical occurrence of hypodontia of primary teeth (i.e. in both sides of jaws) was significantly higher in boys (56.3%) than in girls (28.6%). In permanent dentition symmetrical occurrence of hypodontia was significantly higher than in primary dentition (81.3% in boys and 57.1% in girls). The most frequently missing primary teeth were maxillary lateral incisors (48.8%) followed by mandibular central incisors (34.9%). Hyperdontia of primary teeth has been found only in boys, and it related only to the maxillary lateral incisors. Anomalies of deciduous teeth show a high degree of association with the finding in the permanent dentition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Growth of the anterior dental arch in black American children: A longitudinal study from 3 to 18 years of age

Dental arch size and form change systematically because of tooth emergence and because teeth migrate into shorter and broader arch forms in the deciduous dentition and again in the permanent dentition. The present longitudinal analysis describes changes in arch form in a cohort of 52 black American children (Nashville, Tenn) between the ages of 3 and 18 years. The anterior (incisor-canine) arch dimensions were analyzed. Incisor-to-canine depth remained static in both arches between 3 and 5 years but shortened significantly between 12 and 18 years. Intercanine width broadened significantly in both arches, first during the deciduous dentition, then again as the primary teeth were supplanted by the permanent incisors and canines. But there was no change in intercanine width once the permanent canines were in functional occlusion (approximately 11-18 years). These changes alter anterior arch form (the ratio depth/width). This index decreased significantly during the deciduous phase as the arches broadened; the index increased from 6 to 10 years as teeth were replaced, then again decreased during the duration of the study (approximately 10-18 years). Dimensions of these black American children all exceed comparable values for white American children, although the anterior shapes are indistinguishable. The present data focus attention on the dynamics of arch form in which considerable, protracted change occurs by physiologic migration, not just during the short phase of tooth replacement.     

Intra-arch occlusal indicators of crowding in the permanent dentition.

INTRODUCTION: The objective of this study was to identify the intra-arch occlusal characteristics that best discriminated 3 groups with different grades of dental arch discrepancies. This cross-sectional analysis was conducted in Lima, Peru, in 2003. METHODS: Intra-arch measurements were made on 150 sets of dental casts of high school students (aged 12-16; 75 boys, 75 girls). Stepwise multiple discriminant analysis (SMDA) was used to obtain a better understanding of the morphological relationships between tooth and dental-arch variables and their relationship with crowding. RESULTS: Mesiodistal tooth sizes and crown proportions of some teeth differed among significantly crowded, mild-to-moderately crowded, and spaced dental arches. Buccolingual tooth sizes were similar in the 3 groups. Of the arch dimensions evaluated, only intermolar arch width and arch length differed between the groups. An SMDA was developed to classify dental-arch discrepancies in the permanent dentition based on several intra-arch occlusal characteristics. The variable with the highest discriminatory capability between groups was arch length. When arch length was taken out of the SMDA, the explanatory capability from the variability on the dental arch discrepancies diminished from 51% to 14%. When the remaining arch dimension variable (intermolar width) was taken out, the explanatory capability diminished more (from 14% to 8%). CONCLUSIONS: Although other tooth-size and arch dimensions are indicators of crowding, arch length is the most important factor.     

Longitudinal observation of developmental change in maxillary deciduous and permanent canines

During the period of the growth and development of the dental arch, anterior-posterior and medial-lateral changes in the maxillary deciduous and permanent canines were longitudinally studied in children. A longitudinal series of dental casts were obtained from 50 children at 2-month intervals from the completion of deciduous dentition to the stable period of permanent dentition. Subjects were divided into two groups according to the arrangement of the permanent teeth: a normal dental arch group and a crowded dental arch group. The mesial and distal points of the deciduous and permanent canines and the most prominent points on the labial and lingual contours were observed longitudinally. The results indicated that the measurement points of the deciduous canines in the normal and crowded groups moved in the anterior and lateral direction. When the amount of movement in the normal group was compared to that in the crowded group, the normal group showed greater movement than the crowded group. The permanent canines in both groups moved in the anterior and medial directions. When the amount of movement in the normal group was compared to that in the crowded group, the normal group showed more anterior movement than the crowded group, and the crowded group showed more medial movement than the normal group. When the distal point of the permanent canine was compared with the point of the deciduous canine at the exfoliation period in the normal arch group, the permanent canine was in almost the same position or was in a more anterior position than the deciduous canine. In the crowded arch group, the permanent canine tended to drift posteriorly.     

Spaced dentition. An epidemiologic study

This epidemiologic study deals with the incidence of spaced dentition in 1279 students between the ages of 12 and 18 years. The sample includes only those with a full complement of permanent teeth (third molars were not considered) and with no apparent etiological conditions that might lead to disruption of dental arch continuity. The sample was evenly divided by age and sex. Frequency of spaced dentition was high, occurring in 51.8% of males and in 45.5% of females. Prevalence was less in higher age groups, and the sexual dimorphism that was significant in the 14 YR-16 YR group was not found in the 16 YR-18 YR group. The mean number of spaces per subject was 6 +/- 4.3 for males and 5 +/- 3.7 for females, again displaying diminishing incidence with age and a concomitant absence of the sexual dimorphism in the highest age group. Spaces were found in both arches in 49.5% of the spaced dentitions, and in only the maxillary arch in 34.3%. Incidence of spacing in the mandibular arch alone was only 16.2%. In most subjects the spaces were distributed equally between the two quadrants of each arch. The most common sites and largest space widths in either dental arch were found between cuspids and the first bicuspids and between cuspids and lateral incisors.     

A controlled study of the morphometric changes in the primary dentition of pre-term, very-low-birthweight children

The aim of the present investigation was to compare the dimensions of the primary incisors from pre-term children and full-term controls. One hundred and eleven pre-term children, consisting of 86 very-low-birthweight (< 1,500 g), 25 low-birthweight (from 1,500 to 2,500 g), and 169 full-term, normal-birthweight (> 2,500 g) children, donated a total of 572 maxillary and mandibular primary central and lateral incisors for study. The teeth were measured by means of a digital micrometer. The results showed that there was a dose-response effect of birthweight on tooth size. The very-low-birthweight teeth showed the smallest dimensions, the normal-birthweight controls the largest, and the low-birthweight teeth intermediate dimensions (p < 0.001). In the maxillary primary central and lateral incisors, and the mandibular primary central incisors, very-low-birthweight teeth were from 6 to 11% smaller in both mesiodistal and faciolingual dimensions compared with normal-birthweight teeth (p < 0.001). The largest differences were observed in the maxillary lateral incisors, where mean decreases of 0.58 +/- 0.45 mm in mesiodistal and 0.50 +/- 0.40 mm in faciolingual dimensions (11% reduction in both measurements) were observed. In addition, in the mandibular and maxillary lateral incisors of very-low-birthweight children, the left-sided teeth were significantly smaller than those on the right side in both mesiodistal and faciolingual dimensions (p < 0.03).     

Dental morphology and crowding. A multivariate approach

The objective of this study was to compare, combined and individually, the mesiodistal (MD) and buccolingual (BL) tooth sizes as well as their respective crown proportions in the permanent dentition in dental arches with moderate, mild, and no crowding. Dental casts from two-hundred 12 to 16-year-old school children from a typical high school from Lima, Peru, were used. The MD and BL tooth sizes of all permanent teeth except second and third molars were measured, and their crown proportion (MD/BL ratio) was estimated. Each dental arch was classified as presenting moderate (-5.1 mm or more of discrepancy), mild (-0.1 and -5 mm of discrepancy), and no crowding (zero or a positive discrepancy). Combined and tooth-specific comparisons among the crowding groups for the tooth sizes as well as crown proportions were performed with a multivariate analysis of variance (MANOVA, using Wilks lambda). Combined MD tooth sizes and crown proportions differed among crowding groups. Subsequent individual comparisons indicated differences for MD tooth size of all upper teeth and for lower premolars and central incisors. Differences were also detected for crown proportions of the upper second premolar, canine, and both incisors; as well as for the lower first premolar, canine, and central incisor. No differences were found for the BL tooth sizes among crowding groups. MD tooth sizes and crown proportions from specific teeth are significantly different between dental arches with moderate, mild, and noncrowded arches. This study helps to understand the odontometric component of the dental crowding multifactorial origin.     

Craniofacial pattern of Class III deciduous dentition.

The purpose of this study was to investigate the morphological characteristics of the cranio-dento-facial complex of children with deciduous dentition and Class III malocclusion. Forty Chinese children in Taiwan with normal occlusion and 40 with Class III malocclusion in deciduous dentition were selected for cephalometric analysis. Mandibular length was significantly greater and the mandible was situated farther forward in the Class III group. The maxilla was also slightly backward in this group, perhaps in association with the shorter maxillary length. The mandibular incisors were tipped lingually to compensate for the intermaxillary skeletal dysplasia and the maxillary incisors were tipped lingually by the retroinclined mandibular incisors.     

A longitudinal study on growth and development of dental arches of primary, mixed and permanent dentitions

In dental clinic for children, criteria for growth and developmental changes related to increases in the width and length of the dental arch at the primary, mixed, and permanent dentition stages are essential. This study was carried out to measure the width and the length of normal dental arch and to make detailed observations of growth and developmental processes in the dental arch at each dentition stage. Materials were serial study casts of the maxilla and the mandible taken every 2 month from 127 children (74 boys and 54 girls). The casts were made from 6 months after birth until the age of 15. Measurements of the width of the dental arch were made between bilateral teeth of the same tooth type, both deciduous and permanent. The length of the dental arch was measured on the basis of the perpendicular distance from the contact point of mesial surfaces of central incisors to a line between bilateral teeth of the same tooth type. Measured values were categorized according to either chronological age or tooth age on the basis of the eruption of the central permanent incisors. The indices of the dental arch with relation to the width and the length at each dentition stage were calculated for the sake of partial and total observations of alterations in dental arch form. The results were as follows: 1) In terms of chronological age, until 1 year before the eruption of permanent replacements, the width of the dental arch gradually decreased in both the maxilla and the mandible in the regions of the deciduous central and lateral incisors. Increasing slightly from about the age of 6 years and the period of mixed dentition, the width of the dental arch remained stable until the permanent dentition stage. From the primary dentition stage, the width of the dental arch in the region of the maxillary and mandibular canines and first and second molars gradually increased. Therefore it remained stable until the eruption of permanent dentition. The width in the region of the permanent maxillary and mandibular first molars gradually increased and attained a stable condition at about 12 years of age. In males, the width in the area of the maxillary secondary molars decreased slightly and tended to decrease in the mandible. In females, on the other hand, the width showed a tendency to increase with advancing ages. With the exception of the second permanent molars, the width between the distance of bilateral teeth were consistently larger in males than in females.(ABSTRACT TRUNCATED AT 400 WORDS)     

Dental arch dimensions in patients with unilateral cleft lip and palate

In this investigation, dental arch dimensions during different ages were studied in 72 children with unilateral cleft of the lip, alveolar process, and palate and were compared with those of normal children. All the children with clefts were treated surgically by surgeons of the Lancaster Cleft Palate Clinic. The dental arch dimensions were studied with the use of dental casts during the time of full deciduous dentition (3 to 4 years of age), mixed dentition (8 to 9 years of age), and permanent dentition (12 years of age). The major findings were: (1) all maxillary interdental widths and lengths were significantly smaller than the normal dimensions at all ages, except for intermolar width at age 12 years; and (2) the mandibular arch dimensions seemed to be related to changes in the maxillary arch; however, the influence of surgical procedures in the maxillary arch is not reflected severely in mandibular arch dental position.     

Mandibular incisor alignment and dental arch changes 1 year after extraction of deciduous canines

This study investigated the early effects on mandibular incisor irregularity and rotation together with dental arch dimensions of the extraction of four deciduous canines. Children, during early mixed dentition, were randomized into one extraction (n = 32) and one control (n = 41) group. Dental casts from baseline (T0) and 1 year follow-up (T1) were used to evaluate changes in the irregularity index and in mandibular incisor rotation, dental arch dimensions, overjet, and overbite. Median mandibular incisor irregularity decreased over time, significantly more in the extraction than the control group (1.2 versus 0.7 mm; P < 0.01), with wide ranges in both groups. Rotational changes greater than 10 degrees for lateral incisors were twice as common in the extraction group (42 versus 20 per cent; P < 0.01). Central incisors displayed only minor changes in both groups. The correlation between changes in irregularity index and changes in incisor rotation was weak in both groups (r(s) < 0.3 not significant). According to professional assessment of overall alignment, 84 per cent in the extraction group versus 34 per cent in the control group (P < 0.001) improved from T0 to T1. A significant decrease in maxillary and mandibular arch length and circumference from T0 to T1 was recorded in the extraction group (1.3, 1.1 mm and 2.4, 2.0 mm, respectively; P < 0.001), while arch dimensions were preserved in the control group. To conclude, 1 year after extraction of the deciduous canines, small improvements in mandibular incisor alignment were seen, together with reduced arch dimensions. Little's index underestimated malalignment related to tooth rotation.     

Meeting Reports

Abstract

This article describes treatment of a patient presenting with a class II malocclusion, maxillary and mandibular crowding, posterior crossbite and an increased deep bite, where the specific treatment goals were achieved in the early mixed dentition by only working on the primary teeth. A Haas-type rapid maxillary expansion (RME) appliance was modified to be anchored on the primary second molars and canines and activated once a day, with each activation equal to 0.20 mm. The appliance was blocked after 30 days and left as a retainer. After 6 months, the RME appliance was removed and bands were cemented to the primary second molars in order to apply traction with headgear. After complete eruption of the mandibular central and lateral incisors, sequential slicing of the lower primary teeth was performed to transfer the leeway space from the distal to the mesial part of the arch. When the patient had entered the permanent dentition, a dental class I relationship was achieved, the crossbite corrected and the crowding improved. The overjet and overbite were also improved. No permanent teeth were involved during this phase of treatment. The outcome of this case report shows that it is possible to work only on primary teeth in the mixed dentition and this can be an effective way to correct a class II malocclusion with deep bite, posterior crossbite and maxillary and mandibular crowding.     

Short-term treatment effects of quad-helix on maxillomandibular expansion in patients with maxillary incisor crowding

The purpose of this study was to evaluate the effects of the maxillary arch expansion on maxillomandibular arch widths in patients treated with the quad-helix versus untreated controls. The treatment group consisted of 50 consecutive patients treated for maxillary incisor crowding with a quad-helix appliance in the early mixed dentition. Lateral cephalograms and dental casts taken at the start (T0) and end (T1) of the quad-helix treatment were obtained. The control group consisted of 50 untreated patients with the same type of malocclusion. Two consecutive lateral cephalograms and dental casts of each untreated patient were taken at about the same time as T0 and T1. All these study materials were analyzed for comparison between the two groups. The mean ages at T0 and T1 in the two groups were about the same. The maxillary first molars moved and tipped distally in the treatment group and mesially in the control group. The quad-helix treatment actually expanded the mandibular and maxillary arches concurrently. The more the maxillary arch widths were expanded and the less the maxillary first molars were inclined distally, the more the mandibular arch widths were expanded. The quad-helix activation caused lingual tipping and mesiobuccal rotation of the maxillary first molars. The mesiobuccal rotation of the maxillary first molars could turn molar occlusal relationships for the better from Class II to Class I. The quad-helix treatment gives rise to spontaneous expansion of the mandibular arch concurrent with maxillary expansion in the early mixed dentition patients with maxillary incisor crowding.