Dental arch space and permanent tooth size in the mixed dentition of a skeletal sample from the 14th to the 19th centuries and 3 contemporary samples

Digital analyses of Bolton tooth size ratios and their association to gender, angle class, and other occlusal traits: a study using a partially automated digital 3D model analysis

BACKGROUND

This study aims to verify Bolton's values for tooth size ratios and to evaluate possible relationships to different occlusal traits using precise digital measurement methods.

MATERIALS AND METHODS

Including 1000 consecutively selected patients from three study centres a digital, partially automated model analysis was performed utilizing the software OnyxCeph. The measurements comprised tooth width for calculation of anterior (AR) and overall ratio (OR) as a percentage, arch width, length, perimeter, overjet, overbite, space analysis in millimetre and the assessment of the angle classification.

RESULTS

AR and OR were significantly increased compared to Bolton's ratios of 77.2% (AR) and 91.3% (OR). In the gender comparison, male patients showed larger tooth size ratios, especially in the OR. Patients with Angle Class II/1 and II/2 had smaller tooth size ratios than patients with Angle Class III and I. Thus, patients with Angle Class II/1 had the largest tooth diameters in all maxillary teeth and with Angle Class II/2 the smallest tooth sizes in the mandible. The largest tooth widths in the lower jaw were observed in the Angle Class III patient group. Furthermore, a negative correlation from AR/OR to overjet, overbite, and available space in lower jaw as well as a positive correlation to available space in upper jaw was detected.

CONCLUSIONS

There is a clear correlation between the tooth size ratios and the present dysgnathia as well as other orthodontically relevant occlusal traits. This prior knowledge about our patients is extremely important to create an individualized treatment plan and enable sufficient occlusion. To achieve a functionally good occlusion with correct overjet and overbite, it is essential that the maxillary and mandibular teeth are proportional in size. Any deviation from the ideal patient in terms of tooth size, number, shape, or arch must be considered in the pre-therapeutic treatment plan in combination with the existing dysgnathia in order to be able to achieve a stable anterior and posterior occlusion with appropriate adjustments to the therapy post-therapeutically.

Understanding the relationship between orofacial structures and feeding habits of preschoolers: A multivariate analysis

The understanding of the relationship between orofacial structures and feeding habits in preschoolers is helpful for health professionals and those dedicated to food science. The hypothesis tested was whether this relationship is already present even at a very young age. This cross-sectional study included 91 healthy caries-free children (50 girls/41 boys; 3.4-6.2 years; mean 4.1 years) and a comprehensive evaluation of the stomatognathic system was performed: dietary intake, facial and occlusal morphology, gustatory sensitivity, bite and lip forces, and orofacial myofunctional aspects (mastication, swallowing and breathing functions). Principal component analysis summarized the variables related to the form and function of the orofacial aspects; further, K-means analysis identified two clusters of participants with similar aspects. Cluster 1 ("Low orofacial myofunctional functioning"; n = 51) was characterized by children who showed the worst performance of mastication, swallowing and breathing functions and whose parents reported the consumption of sweets, cookies, chocolate, but not fresh fruits the day before, in addition to the higher bottle-feeding and pacifier use duration. This cluster also showed higher sweet taste threshold. Cluster 2 ("High orofacial myofunctional functioning"; n = 40) showed lower bottle-feeding and pacifier use duration, higher gustatory sensitivity, greater maxillo-mandibular dimensions, and better orofacial function performance. The variables sex and BMI did not associate to clusters profile. The frequencies of open bite and current sucking habit (pacifier) also differed between clusters. The results showed that an association between form and function of the structures that comprise the stomatognathic system and dietary intake is already present in children with primary dentition.

Influence of age and diet consistency on the oral muscle pressure of orthodontically treated and untreated subjects with normal occlusion and comparison of their 3D facial shape

OBJECTIVES

(1) To investigate the effect of age and diet consistency on maximum lips, tongue and cheek pressure of orthodontically treated and untreated subjects with normal, Class I dental occlusion, (2) to find out whether there is a muscle imbalance between anterior tongue and lip pressure in the same subjects at different ages and (3) to compare the 3D facial shape of treated and untreated individuals.

MATERIAL AND METHODS

Subjects with normal occlusion were prospectively grouped into orthodontically treated/untreated and in children/adolescents/adults. Iowa Oral Performance Instrument was used to record the maximum muscle pressure. Two-way ANOVA and Tukey post hoc test analysed age-specific differences in muscle pressure. Two-way ANCOVA analysed the effect of diet consistency on muscle pressure. Lips and tongue imbalance was analysed using z-scores and 3D faces using a generalized Procrustes analysis.

RESULTS

One hundred thirty-five orthodontically untreated and 114 treated participants were included. Muscle pressure was found to increase with age in both groups, except for the tongue in treated subjects. No differences in the balance between lips and tongue muscle pressure were found, but a higher cheek pressure in untreated adults (p<0.05) was observed. 3D facial shapes showed subtle differences. Untreated subjects with soft diet consistency showed lower lip pressure (p<0.05).

CONCLUSION

Oral muscle pressure of orthodontically treated patients without relapse does not differ from that of untreated patients with Class-I occlusion.

CLINICAL RELEVANCE

This study provides normative lip, tongue and cheek muscle pressure in subjects with normal occlusion, which can be used for diagnosis, treatment planning and stability.

The Crown Size and Sexual Dimorphism of Permanent Teeth in Jordanian Cleft Lip and Palate Patients

Objective:

To provide a detailed description of crown size dimensions in the permanent dentition of Jordanian cleft lip and palate patients and to compare the findings with those of other populations.

Method:

The mesiodistal crown diameters of the permanent teeth of 47 patients with unilateral cleft lip and palate (UCLP), 25 patients with bilateral cleft lip and palate (BCLP), and 74 controls were measured.

Results:

The cleft group (UCLP and BCLP patients) generally demonstrated a smaller tooth size for both the maxillary and mandibular arches than did the control group. A sexual dimorphism pattern with males having larger teeth than females was observed for controls and UCLP patients. More males with BCLP had smaller teeth than did females. In the maxilla, the UCLP cleft-side teeth showed the largest percentage (4%) of sexual dimorphism, whereas the BCLP teeth achieved the highest percentage (3.4%) in the mandible. The UCLP cleft-side maxillary lateral incisors (13.2%) and BCLP mandibular canines (6%) displayed greater sexual dimorphism in crown size than did any other tooth class.

Conclusions:

Tooth size reduction occurred across all permanent tooth types and among early and late-forming teeth in cleft patients compared with the controls. This reduction was more pronounced in the maxillary incisor field. Males with UCLP and control males had larger teeth than did females, whereas a reversal of the normal dimorphism pattern was observed in patients with BCLP.

Dental occlusion analysis in the Mesolithic-Neolithic Age, Bronze Age, and Roman to Medieval times in Serbia: Tooth size comparison in skeletal samples

OBJECTIVE

Anthropological studies have reported that tooth size decreases in the context of diet changes. Some investigations have found a reverse trend in tooth size from the prehistoric to the modern times. The aims of this study were to analyze tooth size in skeletal samples from Mesolithic-Neolithic Age, Bronze Age, and Roman to Medieval times to determine sex differences and establish a temporal trend in tooth size in the aforementioned periods.

DESIGN

Well-preserved permanent teeth were included in the investigation. The mesiodistal (MD) diameter of all teeth and buccolingual (BL) diameter of the molars were measured. Effects of sex and site were tested by one-way ANOVA, and the combined effect of these factors was analyzed by UNIANOVA.

RESULTS

Sexual dimorphism was present in the BL diameters of all molars and MD diameters of the upper first and the lower third molar. The lower canine was the most dimorphic tooth in the anterior region. The MD diameter of most teeth showed no significant difference between the groups, (sample from: Mesolithic-Neolithic Age-group 1; Bronze Age-group 2; Roman times-group 3; Medieval times-group 4), whereas the BL diameters of the upper second and the lower first molar were the largest in the first group. Multiple comparisons revealed a decrease in the BL diameter of the upper second and the lower first molar from the first to the later groups. Lower canine MD diameter exhibited an increase in the fourth group compared to the second group.

CONCLUSION

On the basis of the MD diameter, a temporal trend could not be observed for most of the teeth. The lower canine exhibited an increase in the MD diameter from the prehistoric to the Medieval times. Changes of BL diameter were more homogeneous, suggesting that the temporal trend of molar size decreased from the Mesolithic-Neolithic to Medieval times in Serbia.

Can extraction sites affect the profile?

Tooth extractions, apart from the third molars, which it seems is normal to extract today, have always given rise to controversy among orthodontists with both supporters and opponents. It is legitimate to raise the question regarding the need for extractions in our treatment plan and to opt for the first or second premolars as the extraction site, or even the first molars when the latter are decayed and the germs of the third molars are in place. Facial esthetic guides us in our treatment decisions but we must free ourselves from the so-called esthetic lines drawn up many years ago and, for the most part, on the basis of lateral headfilms and small study samples. Particular ethnic features are another major factor to be borne in mind, given that the vast majority of cephalometric standards were based on Caucasian populations. In this article, we will draw on clinical studies to illustrate the thinking behind the need for extractions and the choice of extraction sites.

Dental crowding

Objective:

To evaluate the role of genetics and tooth wear in the etiology of dental crowding through the analysis of a split indigenous Amazon population.

Materials and Methods:

Dental crowding prevalence (n  =  117), tooth wear (n  =  117), and inbreeding coefficient (n  =  288) were compared for both villages. A biometric investigation was performed by dental cast analysis of 55 individuals with no tooth loss. Mann-Whitney statistics, independent t-tests, and Fisher exact tests were used at P &lt; .05.

Results:

A high coefficient of inbreeding was confirmed in the resultant village (F  =  0.25, P &lt; .001). Tooth wear was not significantly different (P  =  .99), while a significantly higher prevalence of dental crowding was confirmed in the original village (PR  =  6.67, P  =  0.02). Forty dental arches (n  =  20) were examined in the new group, and only one (2.5%) had a dental crowding ≥5 mm. In the original villages, we found 20 arches (28.6%) with dental crowding. No difference was observed for tooth size, while larger dental arch dimensions explained a lower level of dental crowding in the resultant village.

Conclusions:

Our findings downplay the widespread influence of tooth wear, a direct evidence of what an individual ate in the past, on dental crowding and emphasize the role of heredity, exacerbated through inbreeding, in the etiology of this malocclusion.

Variability in permanent tooth size of three ancient populations in Xi'an, northern China

OBJECTIVES

This paper compares permanent dental dimensions between three ancient populations that belonged to the same biological population throughout a temporal range of 2000 years to detect temporal trends and metric variation in dentition.

MATERIALS AND METHODS

The samples analysed were dental remains of 4502 permanent teeth from 321 individuals, which were excavated from three archaeological sites: Chang'an (1000-1300 years BP), Shanren (2200 years BP) and Shaolingyuan (3000 years BP) in the Xi'an region (northern China). For each tooth three standard measurements were taken: Mesiodistal (MD) diameter of crown, labiolingual or buccolingual (BL) diameter of crown and length of root (LR).

RESULTS

Three ancient population samples generally displayed the same dental dimensions (p>0.05), whereas some tooth types varied. The Shaolingyuan had larger canine and the smallest maxillary second molars and the Chang'an had the largest mandibular first molars in the MD dimension. The Shanren had the smallest maxillary third molars and mandibular central incisors, and the Chang'an had the smallest maxillary lateral incisors in the BL dimension. In the LR measures, statistically significant differences of five tooth types showed that the Chang'an were smaller than the Shaolingyuan and the Shanren. Comparisons of coefficients of variation for teeth showed that the length of root and third molar usually displayed greater variation.

CONCLUSIONS

Decreasing or increasing trend for crown size does not occur between the ancient populations, while changes in crown size of a few tooth types fluctuate. The root size is more variable than the crown size and is likely to reflect a degenerated trend in a few tooth types.

Dental occlusion in a split Amazon indigenous population: genetics prevails over environment

Background

Studies examining human and nonhuman primates have supported the hypothesis that the recent increase in the occurrence of misalignment of teeth and/or incorrect relation of dental arches, named dental malocclusion, is mainly attributed to the availability of a more processed diet and the reduced need for powerful masticatory action. For the first time on live human populations, genetic and tooth wear influences on occlusal variation were examined in a split indigenous population. The Arara-Iriri people are descendants of a single couple expelled from a larger village. In the resultant village, expansion occurred through the mating of close relatives, resulting in marked genetic cohesion with substantial genetic differences.

Methodology/Principal Findings

Dental malocclusion, tooth wear and inbreeding coefficient were evaluated. The sample examined was composed of 176 individuals from both villages. Prevalence Ratio and descriptive differences in the outcomes frequency for each developmental stage of the dentition were considered. Statistical differences between the villages were examined using the chi-square test or Fisher's exact statistic. Tooth wear and the inbreeding coefficient (F) between the villages was tested with Mann-Whitney statistics. All the statistics were performed using two-tailed distribution at p≤0.05. The coefficient inbreeding (F) confirmed the frequent incestuous unions among the Arara-Iriri indigenous group. Despite the tooth wear similarities, we found a striking difference in occlusal patterns between the two Arara villages. In the original village, dental malocclusion was present in about one third of the population; whilst in the resultant village, the occurrence was almost doubled. Furthermore, the morphological characteristics of malocclusion were strongly different between the groups.

Conclusions/Significance

Our findings downplay the widespread influence of tooth wear, a direct evidence of what an individual ate in the past, on occlusal variation of living human populations. They also suggest that genetics plays the most important role on dental malocclusion etiology.

Orthodontic anomalies and malocclusions in Late Antique and Early Mediaeval period in Croatia

OBJECTIVE

Malocclusions are relative infrequently analysed in bioarchaeological investigations and if investigated the samples are very small. This research provides analysis of orthodontic anomalies of even 1118 individuals from the Late Antique (LA) and Early Mediaeval (EM) period. Aims were to describe the prevalence of orthodontic anomalies in this historical period and to analyse which orthodontic anomalies are best suitable for bioarchaeological investigations.

METHODS

1118 skulls were examined for anomalies of tooth number, tooth displacement (rotation, malposition, diastema and crowding) as well as for malocclusions.

RESULTS

The prevalence of hypodontia in the LA was 41.02% and 30.61% in the EM sample. Tooth displacement was noticed in 15.63% individuals from the LA and in 12.42% individuals from EM. About 26% of the LA sample and 7.19% of the EM sample were affected with tooth crowding and the difference was statistically significant.

CONCLUSION

Orthodontic anomalies affecting only one tooth or group of teeth are more suitable for examination in bioarchaeological investigations than orthodontic features requiring presence of both jaws and all or almost all teeth. Clinical investigation protocols and methodology should be adopted for bioarchaeological researches and international standards and recommendations should be established for this kind of investigation on skeletal remains.

Características do tipo de alimentação e da fala de crianças com e sem apinhamento dentário

OBJETIVO: caracterizar o tipo de consistência alimentar e a articulação da fala em crianças com oclusão normal e com apinhamento dentário, verificando-se possíveis correlações e interferências. MÉTODOS: participaram 60 crianças, de ambos os sexos, entre 7 e 12 anos, divididas em dois grupos. G1: 30 crianças com apinhamento dentário, G2: 30 crianças sem apinhamento dentário, conforme avaliação odontológica. Foram critérios de exclusão: déficits neurológicos e cognitivos, presença de hábitos orais, respiração oral crônica, deformações dentofaciais, realização de tratamento ortopédico/ortodôntico e/ou fonoaudiológico. Foram realizadas: avaliação do sistema estomatognático; avaliação odontológica quanto à situação dento-oclusal; aplicação de questionários aos pais visando contemplar critérios de exclusão e definir os hábitos alimentares quanto à sua consistência; avaliação de fala quanto à produção fonética e fonológica. RESULTADOS: crianças sem apinhamento dentário têm alimentação predominantemente dura, enquanto aquelas com apinhamento dentário têm alimentação predominantemente amolecida; caracterizada principalmente pelo hábito de ingestão de líquido na presença do alimento na boca. Quanto à fala, não foram encontradas alterações significativas independente do apinhamento dentário e do tipo de consistência alimentar. CONCLUSÃO: há indícios de que a presença do apinhamento dentário relaciona-se à consistência alimentar. A alimentação amolecida parece constituir provável fator etiológico ou contribuinte à existência do apinhamento dentário. O tipo de alimentação e a presença de apinhamento dentário parecem não interferir na articulação da fala.

Mandibular permanent first molar and incisor width as predictor of mandibular canine and premolar width

INTRODUCTION

Estimating the mesiodistal widths of unerupted permanent canines and premolars is an essential aspect of mixed dentition analysis. Several methods are used to predict tooth width. The best methods demonstrate high values of correlation and determination coefficients. In this study, we aimed to determine a linear regression equation that would predict the sum of the mesiodistal widths of mandibular permanent canines and premolars based on the sum of the widths of the 4 mandibular permanent incisors and first permanent molars.

METHODS

The sample consisted of 500 dental casts, obtained from white Brazilian patients (250 male, 250 female; average ages, 13.8 and 14.4 years, respectively). Mesiodistal tooth widths were measured with an electronic digital caliper. Intraclass correlation coefficients were used to determine measurement consistencies. Paired and unpaired Student t tests were used to determine right/left side and sex differences, respectively. A paired Student t test was also used to compare the predicted and actual sums of the mandibular permanent canines and premolars.

RESULTS

We found high values of correlation (r) and determination (r2) coefficients, varying from r = 0.795 to r = 0.81, and r2 = 0.599 to r2 = 0.656. These values are among the highest described in the literature for nonradiographic prediction methods. On average, there was no difference between predicted and actual widths of the mandibular permanent canines and premolars, and the standard errors of estimation were 1.49 mm for males, 1.36 mm for females, and 1.44 mm for the total sample (considering right and left sides of the mandibular arch together).

CONCLUSIONS

The proposed method showed good accuracy and was easy to use, but it must be tested in other populations.

Malocclusion frequency in Swedish and immigrant adolescents--influence of origin on orthodontic treatment need

Sweden has become increasingly multicultural. In the year 2000, almost 25 per cent of the child and adolescent population was of foreign origin. Such a major change in demographics may lead to altered orthodontic treatment need in the community, with implications for planning appropriate levels of orthodontic resources. The aim of this study was to compare the frequency of malocclusion and orthodontic treatment need in 12- and 13-year olds of Swedish and immigrant background. The subjects, n = 493, were stratified into four groups according to family origin: (A) subject and both parents born in Sweden, and subject or at least one parent born in (B) Eastern Europe, (C) Asia, or (D) other countries. Registrations were based on available radiographs, patient records, and a clinical examination. Normative treatment need was based on a number of variables. Treatment need was expressed according to the dental health component (DHC) and aesthetic component (AC) of the Index of Orthodontic Treatment Need (IOTN). Group A exhibited the greatest space deficiencies and irregularities in the maxillary and mandibular anterior segments and also the greatest overjet. More primary molars had been extracted in groups B and C, with a positive correlation between early extraction of primary molars and retention of permanent successors. Self-assessed orthodontic treatment need, IOTN-AC, was highest in group A. For all four groups, the orthodontist's estimate of treatment need was significantly higher than the subjects' self-assessed need. This study confirms that, despite the change in demographics, variations in frequencies of malocclusion and treatment need among children of different cultural background are only minor and the overall orthodontic treatment need remains unchanged.

Are malocclusions more prevalent and severe now? A comparative study of medieval skulls from Norway

INTRODUCTION

The prevalence of malocclusion in modern populations is higher than in excavated samples from ancient times. Presently, more than 30% of children and adolescents in the Scandinavian countries receive orthodontic treatment. The aims of this study were to describe the prevalence and severity of malocclusions in a sample of medieval Norwegians, to evaluate the need for treatment by using the Norwegian need for orthodontic treatment index (NOTI), and to compare these findings with a modern sample already analyzed with the same index.

METHODS

The material consisted of 85 male and 61 female medieval skulls from abandoned and later excavated graveyards of 16th century Oslo that were evaluated with the NOTI.

RESULTS

Only 36% of the medieval group showed objective assessed needs for orthodontic treatment, compared with 65% of the present-day sample. Among the skulls, the objective needs for treatment were 27% for the males and 49% for the females. No sex differences related to severity or prevalence of malocclusion were found in the modern sample. The medieval sample arranged according to severity was great need (B), 7%; obvious need (C), 29%; and little/no need (D/E), 64%. The findings in the modern sample were B, 20%; C, 44%; and D/E, 35%. The female skulls showed greater severity and prevalence than the male skulls. No skull had very great need (A).

CONCLUSIONS

This study indicates a significant increase in both the prevalence and the severity of malocclusions during the last 400 to 700 years in Oslo, Norway. Furthermore, although no sex differences were found in the modern sample, females had both a higher prevalence of malocclusions and more severe malocclusions than did males in the past.

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.