Article

Modification of Tooth size and shape in Down's Syndrome

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Abstract

Individuals with Down's syndrome (DS) tend to display a reduction in size of permanent teeth, and reduced intercuspal distances in molars. A total of 51 permanent maxillary 1st molars of 26 DS children were examined from dental casts, 65 permanent maxillary 1st molars of normal children were examined from dental casts of 33 individuals. The following measurements were performed on both right and left molars (teeth 16 and 26 respectively): (1) all intercusp distance (distobuccal, db; distolingual, dl; mesiobuccal, mb; mesiolingual, ml); (2) the db-mb-ml, mb-db-ml, db-ml-mb, dl-mb-db, mb-dl-db, and dl-db-mb angles; (3) the area of the quadrangle shaped by connecting the cusp tips. All the intercusp distances were significantly smaller in the DS group. Stepwise logistic regression, applied to all the intercusp distances, was used to build a multivariate probability model for DS and normals. The mb-dl and mb-ml distances of the upper right molar (tooth 16) were sufficient to discriminate between DS and normal teeth: [table: see text] The probability for DS is higher when mb-ml is relatively higher in the mb-ml/mb-dl ratio. Another logistic analysis based on groups of angles revealed a combination of 3 angles which gave highly statistically significant discrimination between both groups: the mb-db-dl angle was higher in DS, the mb-dl-db angle was slightly smaller in DS, and the mb-ml-db angle was slightly smaller in DS. The dl cusp was located closer to the centre of the tooth. The change in size occurs at an early stage, while the change in shape occurs in a later stage of tooth formation in DS population. Our probability model for DS teeth is simple and practical because it requires only 2 intercusp distances to be put into the formula.

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... Individuals with Down's syndrome (DS) tend to display a reduction in size of permanent teeth, and reduced intercuspal distances in molars (McMillan & Kargashian, 1961 ; Cohen et al. 1970 ; Geciauskas & Cohen, 1970 ; Townsend, 1983 ; Brown & Townsend, 1984 ; Prahl-Anderson & Oerlemans, 1976). A recent study demonstrated that in the permanent maxillary 1st molar of DS children, all intercuspal distances were significantly smaller than in normal children, as well as the area of the quadrangle shaped by connecting the cusp tips (Peretz et al. 1996). This study also provided a simple probability model for DS which was based on stepwise logistic regression and included the distances between the mesiobuccal and distolingual cusps (mb-dl), and the distance between the mesiobuccal and mesiolingual cusps (mb-ml). ...
... The model in our article provides a tool for predicting the probability for Down's syndrome from mandibular molars. This model adds to our previous model for predicting the probability for Down's syndrome from maxillary molars (Peretz et al. 1996). Since asymmetry in crown size is more pronounced in children with syndromes such as Down's or fragile X (Bailit et al. 1970 ; Garn et al. 1970 a, Peretz et al. 1988), we tested for differences between DS and normal teeth on tooth 36 and tooth 46 separately, although in this study no significant differences were found between the 2 sides. ...
... This demonstrates the strength of the model. In our previous report, the model worked best on tooth 16 (Peretz et al. 1996). ...
Article
A total of 50 permanent mandibular 1st molars of 26 children with Down's syndrome (DS) were examined from dental casts and 59 permanent mandibular 1st molars of normal children were examined from 33 individuals. The following measurements were performed on both right and left molars (teeth 46 and 36 respectively): (a) the intercusp distances (mb-db, mb-d, mb-dl, db-ml, db-d, db-dl, db-ml, d-dl, d-ml, dl-ml); (b) the db-mb-ml, mb-db-ml, mb-ml-db, d-mb-dl, mb-d-dl, mb-dl-d angles; (c) the area of the pentagon formed by connecting the cusp tips. All intercusp distances were significantly smaller in the DS group. Stepwise logistic regression, applied to all the intercusp distances, was used to design a multivariate probability model for DS and normals. A model based on 2 distances only, mb-dl and mb-db, proved sufficient to discriminate between the teeth of DS and the normal population. The model for tooth 36 for example was as follows: formula here A similar model for tooth 46 was also created, as well as a model which incorporated both teeth. With respect to the angles, significant differences between DS and normals were found in 3 out of the 6 angles which were measured: the d-mb-dl angle was smaller than in normals, the mb-d-dl angle was higher, and the mb-dl-d angle was smaller. The dl cusp was located closer to the centre of the tooth. The change in size occurs at an early stage, while the change in shape occurs in a later stage of tooth formation in the DS population.
... With the exception of some authors who studied all the teeth of both arches in persons with DS, 24,25 the maxillary teeth have been evaluated in few articles to date, 26 and this limits our ability to compare our results with those obtained by other investigators. We selected the central incisors, canines, and first molars to have at least 2 permanent teeth in the anterior sector and 1 multirooted tooth in the posterior sector; assuming a normal chronology of tooth eruption, this permitted the inclusion of young participants in the study. ...
... Microdontia of the permanent teeth is considered a phenotypic characteristic of DS. 24,31 However, this statement is based mainly on studies that evaluated only crown dimensions in 1 group of teeth, such as the mandibular incisors, 25,32 the mandibular first molars, 33,34 or the maxillary first molars. 26 The largest series to date appears to be that published by Townsend 24 ; it included 147 children and young adults with DS and 265 controls. That study confirmed that the dimensions of all permanent teeth were smaller in the DS group than in the healthy controls. ...
... These findings were attributed to a transitory acceleration of mitotic activity during the first weeks of embryonic life, before the characteristic growth delay detected during the second trimester of pregnancy. 26,33 It has been suggested that both the proliferation and apposition of enamel and dentin are affected in the permanent molars of persons with DS. 32 The reductions in the thickness of the enamel and dentin occur in the context of a generalized deceleration of the growth process, which is observed in DS from the second year of life onward, 35 showing that this trisomy affects both ectodermal and mesenchymal tissues. 32 In our series, the root portions of the maxillary permanent central incisors, canines, and first molars were smaller in the DS group than in the matched controls. ...
Article
The literature on tooth dimensions in subjects with Down syndrome (DS) is scarce. To our knowledge, no studies have yet been published in which the morphometry of the teeth in DS subjects has been determined using computed tomography. The study group consisted of 40 subjects with DS, aged 10 to 40 years. An age- and sex-matched control group was selected. Cone-beam computed tomography images were retrieved from the archive of the Santiago de Compostela University in Spain. The maxillary central incisors, canines, and first molars were evaluated. The following variables were analyzed: overall tooth length, crown height, root length, mesiodistal diameter, vestibular-palatine diameter, crown-to-root ratio, and cervical circumference. The teeth of subjects with DS were smaller than those of the controls, although the crown-to-root ratio was maintained. No clear sexual dimorphism was detected, but the root lengths of the incisors were greater in male subjects. Crown height, mesiodistal diameter, and crown-to-root ratio showed progressive reductions with age. There appeared to be a degree of "fluctuating dental asymmetry" with respect to vestibular-palatine diameter and cervical circumference. Our findings confirm microdontia of the permanent teeth and progressive reductions in tooth sizes with age in persons with DS. These variations might be relevant to orthodontic treatment planning. Copyright © 2014 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.
... The form of the human teeth and their normal variations as well as the influence of sex and race have been widely analyzed by both anatomical and anthropological descriptions and clinical investigations (Abe et al., 1996;Ash, 1993;Dalidjan et al., 1995;Du-Brul, 1986;Hattab et al., 1996;Kitagawa et al., 1996;Lautrou, 1982;Merz et al., 1991;Peretz et al., 1996;Scott and Symons, 1961;Williams et al., 1989). Form can be viewed as a combination of size and shape. ...
... Shape refers to the structure independent from its orientation, relation to reference planes, and dimension (or size) (Lestrel, 1989). Exhaus-tive quantitative information exists about dental size only, in particular about linear measurements of both crown and root (Abe et al., 1996;Anderson et al., 1977;Ash, 1993;Dalidjan et al., 1995;DuBrul, 1986;Hattab et al., 1996;Lautrou, 1982;Merz et al., 1991;Peretz et al., 1996;Wood et al., 1991). Indeed, the conventional metric measurements commonly used in biological studies provide quantitative information about size but do not completely separate the effects of size and shape on form and form modifications (Ferrario et al., 1995a;Lestrel, 1989;Lestrel et al., 1977;Lowe et al., 1994). ...
... Dental shape is usually analyzed from a qualitative point of view (e.g., presence of nonmetric characteristics) or using angles or ratios between different measurements (Kelley, 1995;Kitagawa et al., 1996;Peretz et al., 1996). Indeed, angles and ratios provide not only just a crude estimate of shape, but also ratios are not really size-independent (Albrecht et al., 1993;Kelley, 1995) and do not allow separate quantification of the size and shape components of the biological form. ...
Article
Form can be viewed as a combination of size and shape. Shape refers to the boundary outline independently from its orientation, relation to reference planes, and dimension (or size). Shape and its changes could be quantified by mathematical methods such as the Fourier series. In this investigation, Fourier analysis has been used to quantify the morphologic characteristics (size and shape) of the outline of the occlusal surface and maximum circumference (equator) in 259 normal, healthy human first permanent maxillary and mandibular molars and to assess the effect of sex. Large within-group variability was found in the Fourier coefficients. Both equatorial and occlusal molar areas were on average larger in male than in female homologous teeth, but the difference was statistically significant only for the equatorial areas. The mean ratios between equatorial and occlusal dental areas were independent from arch (maxillary and mandibular), side, or sex. Both equatorial and occlusal outlines of left and right homologous molars within sex and arch were similar, without size and shape differences. Similarly, no sex differences in shape were found in the comparison of homologous teeth. The method used in the present study could supply information about dental shape in both its entirety and local variations. In particular, the method is extremely sensitive to local variations in dental shape, and it could be usefully employed to compare single teeth to a standard.
... Individuals with Down's syndrome (DS) tend to display a reduction in size of permanent teeth, and reduced intercuspal distances in molars (McMillan & Kargashian, 1961 ; Cohen et al. 1970 ; Geciauskas & Cohen, 1970 ; Townsend, 1983 ; Brown & Townsend, 1984 ; Prahl-Anderson & Oerlemans, 1976). A recent study demonstrated that in the permanent maxillary 1st molar of DS children, all intercuspal distances were significantly smaller than in normal children, as well as the area of the quadrangle shaped by connecting the cusp tips (Peretz et al. 1996). This study also provided a simple probability model for DS which was based on stepwise logistic regression and included the distances between the mesiobuccal and distolingual cusps (mb-dl), and the distance between the mesiobuccal and mesiolingual cusps (mb-ml). ...
... The model in our article provides a tool for predicting the probability for Down's syndrome from mandibular molars. This model adds to our previous model for predicting the probability for Down's syndrome from maxillary molars (Peretz et al. 1996). Since asymmetry in crown size is more pronounced in children with syndromes such as Down's or fragile X (Bailit et al. 1970 ; Garn et al. 1970 a, Peretz et al. 1988), we tested for differences between DS and normal teeth on tooth 36 and tooth 46 separately, although in this study no significant differences were found between the 2 sides. ...
... This demonstrates the strength of the model. In our previous report, the model worked best on tooth 16 (Peretz et al. 1996). ...
Article
A total of 50 permanent mandibular 1st molars of 26 children with Down's syndrome (DS) were examined from dental casts and 59 permanent mandibular 1st molars of normal children were examined from 33 individuals. The following measurements were performed on both right and left molars (teeth 46 and 36 respectively): (a) the intercusp distances (mb-db, mb-d, mb-dl, db-ml, db-d, db-dl, db-ml, d-dl, d-ml, dl-ml); (b) the db-mb-ml, mb-db-ml, mb-ml-db, d-mb-dl, mb-d-dl, mb-dl-d angles; (c) the area of the pentagon formed by connecting the cusp tips. All intercusp distances were significantly smaller in the DS group. Stepwise logistic regression, applied to all the intercusp distances, was used to design a multivariate probability model for DS and normals. A model based on 2 distances only, mb-dl and mb-db, proved sufficient to discriminate between the teeth of DS and the normal population. The model for tooth 36 for example was as follows: p(DS) = (e(30.6-5.6(mb-dl)+25(mb-db)))/(1 + e(30.6 5.6(mb-dl)+25(mb db))). A similar model for tooth 46 was also created, as well as a model which incorporated both teeth. With respect to the angles, significant differences between DS and normals were found in 3 out of the 6 angles which were measured: the d-mb-dl angle was smaller than in normals, the mb-d-dl angle was higher, and the mb-dl-d angle was smaller. The dl cusp was located closer to the centre of the tooth. The change in size occurs at an early stage, while the change in shape occurs in a later stage of tooth formation in the DS population.
... The methods of measurement were previously described in detail (Peretz and Smith, 1993;Peretz et al., 1996). In brief, all the variables except the >rob were measured with an image-analyser computer program (CUE 4; Galai Co., Migdal ...
... Therefore, in teeth with three cusps, a change in shape may be observed during crown formation. As existing data suggest that dental development is modified in people with various diseases (Garn, et al., 1979;Townsend, 1983;Brown and Townsend, 1984;Peretz et al., 1988Peretz et al., , 1996, our present findings may expand the range of standards against which to assess the timing of developmental problems in utero or in the first postnatal months. Further research on a larger sample should obviously cast more light on pre-and postnatal development of the tooth crowns. ...
Article
The following morphometric variables were examined in 18 primary maxillary first molars at various stages of development, collected from archaeological excavation sites in Israel: perimeters and areas from the occlusal view; buccolingual and mesiodistal dimensions and intercusp distances; the angle between the line joining the distobuccal, mesiobuccal and lingual cusps; and the height of the mesiobuccal cusp. An image-analysing technique comprising a photographic camera, a monitor, a computer with appropriate software and a digital caliper was used. Significant correlations were demonstrated between most variables. Teeth were divided into two groups according to their stage of development: stage one included all teeth at an early stage of development in which mesiobuccal cusp height was less than 5 mm; stage two included all teeth in later stages of development where mesiobuccal cusp height was greater than 5 mm. All external variables showed an increase in size between the two stages (while, among the internal ones, only the angle between the cusps showed a very small increase). The small sample is a limitation but the results suggest the following: (1) growth of the primary maxillary molar crown occurs with 'bursts' of development ; and (2) a change in the shape of the crown occurs during its formation where the mesiobuccal cusp moves buccally and distally, and the lingual cusp moves mesially.
... Facial profile may also sometimes be concave, with prominent forehead and mandible, and midfacial hypoplasia [Tuxen et al., 2003]. Additionally, alterations in the oral mucosa, in the size and shape of the tongue, and in the number, dimensions, shape, and arrangement of the teeth can be found [Peretz et al., 1996[Peretz et al., , 1998Desai, 1997;Quintanilla et al., 2002]. ...
... The reduced number of subjects in the present investigation prevents any definitive assertion on this matter, but a part of the discordance between the current results and previous literature data may be explained by the dental formula of the analyzed individuals. Alterations in the number, dimensions, shape, and arrangement of the teeth have already been reported for the subjects with Down syndrome [Peretz et al., 1996[Peretz et al., , 1998Desai, 1997;Quintanilla et al., 2002]. ...
Article
The objective of this study was to supply quantitative information about the facial soft-tissues of a group of patients with hypohidrotic ectodermal dysplasia. The three-dimensional coordinates of 28 soft-tissue facial landmarks were obtained by an electromagnetic digitizer in 11 male and 9 female patients with hypohidrotic ectodermal dysplasia aged 7-41 years, and in 318 healthy individuals of the same age, ethnicity, and sex. From the landmarks, facial areas (eyes, ears, nose, and lips) and volumes (nose and lips) were calculated according to a geometrical model of face. Data were compared to those collected in the normal subjects by computing z-scores. Male and female z-scores were not significantly different. In the pooled sample, the deviations from the norm were particularly evident in the lips, with a significant (Student's t-test, P < 0.05) increment of the total lip area (mean z-score: 0.96) and of the vermilion area of the upper lip (mean z-score: 1.07), a finding negatively related (r = -0.632) to the number of teeth present in the mouth. The eye area was reduced in most patients, a finding significant on the left side (mean z-score: -0.76). Most of the facial areas and volumes of the ectodermal dysplasia patients had z-scores deviating only +/-2 standard deviations from the reference groups. Only 4% of measurements had z-scores larger than +/-3. Additionally, a large inter-individual variability was found, together with a certain age-related trend of improvement of the number of measurements within the +/-2 interval. The method allowed a simple, low cost, fast, and non invasive examination of the patients, and provided a quantitative assessment of the deviation from the norm.
... Several maxillo-facial features have been described in subjects with Ds: a skeletal and dental Class III malocclusion, midfacial and mandibular hypoplasia, dental morphological and numerical anomalies, and eruption timing retardation of both the primary and the permanent dentitions ( Peretz et al. , 1996( Peretz et al. , , 1998Uong et al. , 2001 ;Quintanilla et al. , 2002 ;Bagic and Verzak, 2003 ). Moreover, hypotonicity of the orofacial muscles is a common fi nding in these subjects, particularly in those who are institutionalized and who are likely to receive less stimuli from the environment ( Glassman et al. , 2005 ). ...
... The protocol used in the current investigation was devised specifi cally to examine palatal morphology independent of dental landmarks, and was therefore suitable for both dentate and edentulous maxillary arches. Indeed, Ds subjects often lack molar teeth, while it is extremely rare to fi nd complete edentulousness in non-syndromic young adults ( Peretz et al. , 1996 ;Desai, 1997 ;Quintanilla et al. , 2002 ). Only limited data on palatal size and shape in edentulous reference subjects are available in the literature, but these are from an elderly population ( Klemetti et al. , 1996 ). ...
Article
Full-text available
The aim of the present study was to evaluate palatal morphology in Down syndrome (Ds) subjects, focusing on the effect of dental formula on the hard palate to assist clinicians when planning dental rehabilitation. Palatal landmarks were digitized with a three-dimensional (3D) computerized digitizer on the dental casts of 47 Ds subjects (23 dentate males, 9 edentulous males, and 15 dentate females) aged 20–45 years, 37 dentate reference individuals (20 males and 17 females) aged 30–39 years, and 14 edentulous reference males aged 55–72 years. The co-ordinates of the palatal landmarks were used to construct a mathematical equation of palatal shape, independent of dimensions. Palatal length, slope, width, and maximum palatal height in both the sagittal and frontal planes were measured. In males, palatal length, width, and height were significantly influenced by both the syndrome and edentulism (analysis of variance, P < 0.05). The same measurements were significantly reduced in Ds compared with dentate females (t-test, P < 0.05). In the sagittal plane, Ds did not modify palatal shape; in the frontal plane, Ds individuals showed a higher palate. Overall, palatal shape was influenced by both Ds and edentulousness. Therefore, Ds seems to alter the normal palatal size and shape, although verification on larger samples is required. The findings of the present study may encourage more interdisciplinary dentofacial therapy in the dental and orthodontic care of Ds subjects.
... Down syndrome patients are characterized by many dental anomalies, including Class III dental relationship with anterior and posterior crossbites, which have been reported in the literature (Oliveira et al., 2008). Dental abnormalities in the number (fewer), size (smaller) and morphology (peg-shaped and other morphological deficiencies) (Cohen and Winer, 1965;Townsend, 1983;Peretz et al., 1996), and the timing of their development (late dentition) (Garn et al., 1970) are constant features of this syndrome. There is an increased incidence of canine premolar transpositions and of impacted canines (Roger, 1994;Shapira et al., 2000). ...
Article
Full-text available
The prevalence and severity of malocclusion is especially high in Special Needs individuals. Many have medical limitations to the various procedures that are often needed in the pursuit of excellence from orthodontic treatment and almost all have moderate to severe behavioural problems that make treatment delivery difficult or even impossible to achieve, with any degree of reliability. Nevertheless, the parents are highly motivated to "do the best for their child" and are prepared to become integral members of the treatment delivery team. The present article analyzes the difficulties involved and makes recommendations as to how these may be overcome, based on the authors' published studies in this area and on their broad experience in treating these compromised individuals. Emphasis is placed on the use of pharmacological modalities as the means to providing therapeutic access to many of the more difficult patients. Two case reports are provided to illustrate many of the important principles that pertain to these cases.
... Variation in tooth size is influenced by genetic and environmental factors (Bailit, 1975). Some of the factors that contribute to this variability are race (Lavelle, 1972;Bishara et al., 1986Bishara et al., , 1989, sex (Moorrees et al., 1957;Lavelle 1975;Al-Khateeb and Abu Alhaija, 2006;Haralabakis et al., 2006), hereditability (Alvesalo and Tigerstedt, 1974), and the presence of syndromes (Townsend, 1983;Peretz et al., 1996;Bell et al., 2001). ...
Article
Full-text available
To investigate differences in size of the maxillary permanent anterior teeth and arch dimensions between individuals with repaired unilateral cleft lip and palate (UCLP) and a matched control group representing the general population. Retrospective study cast review. Study casts of 30 subjects due to commence orthodontic treatment following an alveolar bone graft (ABG) were collected from the Cleft Lip and Palate Units in South Yorkshire. Thirty control subjects were collected from a previously validated control group of white individuals in South Yorkshire. Casts were analyzed with an image analysis system to measure the dimensions of the maxillary permanent anterior teeth, incisor chord lengths, and the intercanine and intermolar widths. The results were analyzed statistically using paired t-tests and two-way univariate analysis of variance (ANOVA). The mesiodistal widths of maxillary anterior teeth in the study group were smaller than the noncleft control group (p <or= .01). The dimensions of the cleft side maxillary incisors and incisor chord length were smaller (p <or= .05 and p <or= .01 respectively) compared with the noncleft side. The study group maxillary cleft side incisor chord length and maxillary intercanine width were narrower than the control group (p <or= .0001). (1) Anterior teeth are smaller mesiodistally in individuals with UCLP. (2) Maxillary incisors are smaller on the cleft side than the noncleft side. (3) UCLP subjects had smaller maxillary cleft side incisor chord lengths and intercanine widths than the control group despite pre-ABG expansion.
... Per quanto concerne le anomalie di forma (Figura 3), sono descritti denti conoidi a livello del settore frontale (14,28%) e molari taurodonti, in particolare il secondo molare inferiore (66%) (De Moraes ME et al., 2007). I molari presentano solchi e fessure poco profondi (De Moraes ME et al., 2007;Peretz B et al., 1998;Peretz B et al.,1996). Le radici sono frequentemente piccole e di forma conica (Desai SS, 1997). ...
... Affected individuals have smaller molar crowns overall, although the distal cusps are relatively smaller compared to 46,XX females (Mayhall and Alvesalo, 1992). Individuals with Down syndrome also have cuspal differences in their maxillary molars (Peretz et al., 1996). ...
Article
Primate evolutionary studies rely significantly on dental variation given the large role that teeth play in how an organism interacts with its environment (animal and plant) and conspecifics. Variation in cusp size has been shown to vary among primate taxa, although most studies to date focused on extant and extinct hominoids. Here we test the assumed hypothesis that a significant proportion of this variation in baboons is due to the additive effects of genes. We perform quantitative genetic analyses on variation in two-dimensional (2-D) mandibular molar cusp size in a captive pedigreed breeding population of baboons (Papio hamadryas) from the Southwest National Primate Research Center. These analyses show that variation in cusp size is heritable and sexually dimorphic. Additionally, we tested for genetic correlations between cusps on the same crown, between morphological homologues along the tooth row, and between cusp area and crown buccolingual width. We find that four of the six cusp pairs on the first molar have a genetic correlation of one, save for the metaconid-hypoconid and entoconid-hypoconid, which are not statistically different from zero. The second and third molars have lower genetic correlations, although the metaconid-hypoconid correlation is similarly estimated at zero and the entoconid-protoconid correlation is estimated to be one. This cross pattern of genetic and no genetic correlation does not immediately accord with the known pattern of development and/or calcification. We propose two explanative hypotheses.
... Peretz et al. [1998] found significantly smaller D-MB-DL (distal-mesiobuccal-distolingual) and MB-DL-D angles as well as a higher MB-D-DL angle in DS subjects, which means that teeth of the DS individuals were characterized by distal and distolingual cusps located closer to the centre of the tooth. Such a "pattern" of the inter-cusp distances reduction seems to confirm the hypothesis that in DS individuals, the change in size in the mandibular molars occurs at an early stage, while the change in shape occurs at a later stage of tooth formation reflecting the accumulated effects of continued growth retardation [Nery et al. 1975, Peretz et al. 1996. It is interesting that in a high percentage of the subjects, a slightly pronounced shoveling (grade 1 according to the ASU system) on the first upper incisors was noticed. ...
Article
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Morphology of dentition in Polish children with trisomy 21 (Down syndrome) This paper compares the dimensions and non-metric dental traits between Down syndrome patients (DS) and a control group. A total of 1,210 teeth of subjects with Down syndrome (diagnosed as regular trisomy 21 type) were analyzed. The mesiodistal (MD) and labiolingual or buccolingual (BL) diameters of each dental crown were measured, and the selected non-metric dental traits evaluated. The teeth of male and female DS patients were found to have lower values of both measurements compared to controls (excepting for the mesiodistal diameter of the lower mandibular premolar both in males and females). Sexual dimorphism of dental crown dimensions characteristic of contemporary human populations (the highest M-F difference was lower than 6%) was also observed: boys' teeth, particularly canines, are bigger than girls' (2.33 on average). Disorders in maxillary tooth alignment and the faint shoveling of upper central incisors (grade 1 according to ASU scale) were noted significantly more often among Down syndrome patients, but descriptive features correlating with dental crown size were observed more rarely (e.g., the distal accessory ridge on the upper canine and tuberculum Carabelli on the first molar).
... Down syndrome patients are characterized by many dental anomalies, including Class III dental relationship with anterior and posterior crossbites, which have been reported in the literature (Oliveira et al., 2008). Dental abnormalities in the number (fewer), size (smaller) and morphology (peg-shaped and other morphological deficiencies) (Cohen and Winer, 1965;Townsend, 1983;Peretz et al., 1996), and the timing of their development (late dentition) (Garn et al., 1970) are constant features of this syndrome. There is an increased incidence of canine premolar transpositions and of impacted canines (Roger, 1994;Shapira et al., 2000). ...
Article
Full-text available
Due to the medical progress in the past decades, the life expectancy and quality of the physically and/or mentally disabled children have been much improved. While this has facilitated their entry into society, it has also created greater demands on our profession, from those who care for them. A displeasing dental appearance may have a significant emotional impact on an individual's well being and can bias judgments of social acceptability, ability and personality. Gross misplacement of the teeth occurs more often and with much greater severity in the disabled child than in the general population. The increased concern for facial appearance and oral functions has generated an increased demand for orthodontic treatment, but the difficulties imposed by the handicapping conditions have made many practitioners believe that these patients are not amenable to treatment. At the Center for the Treatment of Craniofacial Anomalies in the Orthodontic Department of the Hadassah School of Dental Medicine, Jerusalem we have been treating children with disabilities for several years. An investigation of the referral patterns of our patients has revealed ignorance of dentists, physicians and social workers of what can and may be done to improve the dental and facial appearance of these children. This finding was the principle reason for this article, in which we will show how successful delivery of treatment is possible for many of the disabled.
... The facial profi le may also sometimes be concave, with a prominent forehead and mandible, and mid-facial hypoplasia (Tuxen et al., 2003). Additionally, alterations in the oral mucosa, in the size and shape of the tongue, and in the number, dimensions, shape and arrangement of the teeth can be found (Peretz et al., 1996(Peretz et al., , 1998Desai, 1997;Quintanilla et al., 2002). These modifi cations are obviously all interrelated: the anterior tongue position has been considered a factor explaining the increased occurrence of a Class III malocclusion with crossbite and anterior open bite found in subjects with Down's syndrome when compared with the general population (Quintanilla et al., 2002). ...
Article
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The aim of the present study was to obtain quantitative information concerning the three-dimensional (3D) arrangement of the facial soft tissues of subjects with Down's syndrome. The 3D co-ordinates of 50 soft tissue facial landmarks were recorded by an electromechanical digitizer in 17 male and 11 female subjects with Down's syndrome aged 12–45 years, and in 429 healthy individuals of the same age, ethnicity and gender. From the landmark co-ordinates, geometric calculations were obtained of several 3D facial angles: facial convexity in the horizontal plane (upper facial convexity, mid facial convexity including the nose, and lower facial convexity), mandibular corpus convexity in the horizontal plane, facial convexity including the nose, facial convexity excluding the nose, interlabial angle, nasolabial angle, angle of nasal convexity, left and right soft tissue gonial angles. Data were compared with that collected for the normal subjects by computing the z-scores. Facial convexity in the horizontal plane (both in the upper and mid facial third), facial convexity in the sagittal plane and the angle of nasal convexity were significantly (P < 0.05) increased (flatter) in subjects with Down's syndrome than in the normal controls. Both left and right soft tissue gonial angles were significantly reduced (more acute) in the Down's syndrome subjects. Subjects with Down's syndrome had a more hypoplastic facial middle third with reduced nasal protrusion, and a reduced lower facial third (mandible) than reference, normal subjects.
Article
Qualitative visual inspections and linear metric measurements have been predominant methods for describing the morphology of teeth. No quantitative formulation exists for the description of dental features. The aim of this study was to determine and validate a mathematical process for calculation of the average form of first maxillary molars, including the general occlusal features. Stone replicas of 174 caries-free first maxillary molar crowns from young patients ranging from 6 to 9 years of age were measured 3-dimensionally with a laser scanning system at a resolution of approximately 100,000 points. Then, the average tooth was computed, which captured the common features of the molar's surface quantitatively. This new method adapts algorithms both from computer science and neuroscience to detect and associate the same features and same surface points (correspondences) between 1 reference tooth and all other teeth. In this study, the method was tested for 7 different reference teeth. The algorithm does not involve any prior knowledge about teeth and their features. Irrespective of the reference tooth used, the procedure yielded average teeth that showed nearly no differences (less than +/-30 microm). This approach provides a valid quantitative process for calculating 3-dimensional (3D) averages of occlusal surfaces of teeth even in the event of a high number of digitized surface points. Additionally, because this process detects and assigns point-wise feature correspondences between all library teeth, it may also serve as a basis for a more substantiated principal component analysis evaluating the main natural shape deviations from the 3D average.
Article
Much of a human molar's morphology is concentrated on its occlusal surface. In view of embryologists' recent attention on the determination of crown morphology by enamel knots that initiate cusp formation, we were interested in the arrangement of cusp apices in the definitive tooth. Computer-assisted image analysis was used to measure intercusp distances and angles on permanent maxillary M1 and M2 in a sample of 160 contemporary North American whites. The intent was to generate normative data and to compare the size and variability gradients from M1 to M2. There is little sexual dimorphism in intercusp distances or angles, even though the conventional mesiodistal (MD) and buccolingual (BL) crown size is 2.0% and 4.0% larger in males, respectively, in these same teeth. Dimensions decreased in size and increased in variability from M1 to M2, but differentially. Cusps of the trigon were more stable between teeth, especially the paracone-protocone relationship. Principal components analysis on the six M1 distances disclosed only one eigenvalue above 1.0, indicating that overall crown size itself is the paramount controlling factor in this tooth that almost invariably exhibits a hypocone. In contrast, four components were extracted from among the 12 angular cusp relationships in M1. These axes of variation may prove useful in studies of intergroup differences. A shape difference occurs in M2, depending on whether the hypocone is present; when absent, the metacone is moved lingually, creating more of an isosceles arrangement for the cusps of the trigon. Statistically, correlations are low between occlusal intercusp relationships and conventional crown diameters measured at the margins of the crowns that form later. Weak statistical dependence between cusp relationships and traditional MD and BL diameters suggest that separate stage- and location-specific molecular signals control these different parts (and different stages) of crown formation.
Article
A mathematical representation of tooth morphology may help to improve and automate restorative computer-aided design processes, virtual dental education, and parametric morphology. However, to date, no quantitative formulation has been identified for the description of dental features. The aim of this study was to establish and to validate a mathematical process for describing the morphology of first lower molars. Stone replicas of 170 caries-free first lower molars from young patients were measured three-dimensionally with a resolution of about 100,000 points. First, the average tooth was computed, which captures the common features of the molar's surface quantitatively. For this, the crucial step was to establish a dense point-to-point correspondence between all teeth. The algorithm did not involve any prior knowledge about teeth. In a second step, principal component analysis was carried out. Repeated for 3 different reference teeth, the procedure yielded average teeth that were nearly independent of the reference (less than +/- 40 microm). Additionally, the results indicate that only a few principal components determine a high percentage of the three-dimensional shape variability of first lower molars (e.g. the first five principal components describe 52% of the total variance, the first 10 principal components 72% and the first 20 principal components 83%). With the novel approach presented in this paper, surfaces of teeth can be described efficiently in terms of only a few parameters. This mathematical representation is called the 'biogeneric tooth'.
Thesis
L'hypotonicité générale présente chez les enfants porteurs de trisomie 21 a desrépercussions au niveau de la cavité orale et des différentes fonctions orofaciales,notamment la mastication.Une étude sur la mastication a donc été réalisée dans cette population d'enfants âgés de 7 à 11 ans ainsi que dans une population d'enfants normaux du même âge. Différents paramètres ont été sélectionnés pour évaluer la mastication d'aliments de texture et consistance diverses par enregistrement vidéo.Conjointement, un bilan fonctionnel a été réalisé afin d'expertiser les capacités orales motrices et fonctionnelles.Les résultats ont montré que les enfants atteints de trisomie 21 présentent uneaugmentation du ratio temps/cycle pour de nombreux aliments, une mastication bouche ouverte avec des apparitions et des claquements linguaux associés à la mastication.Des corrélations entre le bilan fonctionnel et la mastication ont mis en évidencel'importance du rôle joué par les sangles labiale, jugale et linguale lors de la mastication.Elles ont montré aussi la nécessité d'une ventilation nasale pour une masticationnormale.Ces données pourraient améliorer la prise en charge des enfants porteurs de trisomie 21.
Article
The objective of this study was to supply quantitative information about the facial soft-tissues of a group of subjects with Down syndrome. The three-dimensional coordinates of 28 soft-tissue facial landmarks were obtained by an electromechanic digitizer in 17 male and 11 female subjects with Down syndrome aged 12-45 years, and in 429 healthy individuals of the same age, ethnicity, and sex. From the landmarks, facial areas (eyes, ears, nose, and lips) and volumes (nose and lips) were calculated according to a geometrical model of face. Data were compared to those collected in the normal subjects by computing z-scores. Male and female z-scores were not significantly different. Most of the facial volumes were significantly (Student's t, P < 0.05) smaller in subjects with Down syndrome than in their normal controls. Ear areas were significantly reduced (mean z-scores in males -2.07 right, -1.9 left; in females -2.11 right, -2.21 left), as well as nasal surface area (mean z-score -1.53 in males, -2.45 in females). In women, age and some z-scores were significantly correlated (P < 0.05): upper lip volume (r = 0.714), left and right eye area (r = 0.635, right; 0.604, left), nasal area (r = 0.603): with increasing age, the negative values of the z-scores approached the 0 value of the reference population. In the pooled sample, age and the z-score of the total lip area were significantly correlated (r = 0.423): increasing age corresponded to a larger z-score value. The method allowed a simple, low cost, fast, and noninvasive examination of the subjects, and provided a quantitative assessment of the deviation from the norm.
Article
Tooth crown size may be determined by both genetic and environmental factors. The aim of this study was to identify quantitative trait loci (QTLs) affecting dental crown size and determine whether there is genetic independence between upper and lower teeth, using SMXA recombinant inbred strains of mice. Mesiodistal and buccolingual crown diameters (MD and BL, respectively) of the upper and lower first molars (M(1) and M(1), respectively) were measured. For each trait, mean values of substrains showed a continuous spectrum of distribution. Genome-wide scan detected QTLs exceeding suggestive threshold levels for MD of M(1) (chromosomes 7, 13, and 17), BL of M(1) (chromosomes 8 and 13), MD of M(1) (chromosomes 7 and 13), and BL of M(1) (chromosomes 3 and 15). These findings suggest that tooth crown size is controlled by multiple genes, and that there is some independence of genetic control between M(1) and M(1).
Article
In pediatric dental clinics, the degree of mandibular angle and anteroposterior manndibular length of a child is costumed to use the prediction of the occlusion of an adult in the case of Class 3 malocclusion. The mandible is a complex structure and the size and shape could be determined by genetic and environmental factors. The purpose of this study was to investigate the genetic factor to the degree of mandibular angle by QTL analysis using SMXA recombinant mice. We measured the degree of mandibular angle in 21 SMXA recombinant inbred (RI) strains and its parental strains, SM/J and A/J.The results were obtained as follows.1.Continuous distribution pattern of the degree of mandibular angle in SMXA RI strains suggests that the angle is not determined by a simple Mendelian inheritance but is controlled by multiple genes.2.It is conceivable that SM/J and A/J-derived alleles include both increasing and decreasing effects on growths of mandibular angle in SMXA RI strains as determined by the combination of SM/J and A/J-derived alleles.3.Based on the QTL analysis, it is suggested that the candidate genes of mandibular angle are mapped to a D 13 Mit 130 on chr. 13 with LOD score of 2.3, and NdA 29 on chr. X with LOD score of 2.2. These findings strongly suggest that mandibular angle is genetically controlled.
Article
Abnormal growth in Down syndrome (DS) is reflected by variable reduction in size and simplification in form of many physical traits. This study aimed to compare the thickness of enamel and dentine in deciduous and permanent mandibular incisor teeth between DS and non-DS individuals and to clarify how these tissues contribute to altered tooth size in DS. Sample groups comprised 61 mandibular incisors (29 permanent and 32 deciduous) from DS individuals and 55 mandibular incisors (29 permanent and 26 deciduous) from non-DS individuals. Maximum mesiodistal and labiolingual crown dimensions were measured initially, then the crowns were sectioned midsagittally and photographed using a stereomicroscope. Linear measurements of enamel and dentine thickness were obtained on the labial and lingual surfaces of the crowns, together with enamel and dentine–pulp areas and lengths of the dentino-enamel junction. Reduced permanent crown size in DS was associated with a reduction in both enamel and dentine thickness. After adjustments were made for tooth size, DS permanent incisors had significantly thinner enamel than non-DS permanent teeth. The DS permanent teeth also exhibited significant differences in shape and greater variability in dimensions than the non-DS permanent teeth. Crown dimensions of deciduous incisors were similar in size or larger in DS compared with non-DS deciduous teeth. Enamel and dentine thicknesses of the deciduous teeth were similar in DS and non-DS individuals. The findings indicate that growth retardation in DS reduces both enamel and dentine deposition in the permanent incisors but not in the earlier-forming deciduous predecessors. The results are also consistent with the concept of amplified developmental instability for dental traits in DS. Am. J. Hum. Biol. 13:690–698, 2001. © 2001 Wiley-Liss, Inc.
Article
Tooth size directly affects abnormalities in dental occlusion, and is decided by genetic and environmental factors. Malalignment of teeth occurs as a result of discrepancies in jaw bone and tooth size. In this study, F2 mice acquired by crossing C57BL/6J (B6) strain having large mesiodistal tooth crowns and MSM strain having small mesiodistal crowns were used to conduct quantitative trait locus (QTL) analysis and to identify chromosomes involved in determining mesiodistal tooth size. Analysis revealed that the QTL responsible for tooth size could be mapped chromosomes 3 and 17 in mice. Therefore, we measured mesiodistal crown length of the first molar of the mandible, and analyzed candidate chromosomes that decide the size of teeth in vivo using consomic mice between B6 and MSM strains. Mesiodistal crown length was largest in consomic mice of B6-Chr.3MSM, thus some genes for mesiodistal crown development may be located on chromosome 3.
Chapter
The formation and maturation of dental tissues constitute an important process in craniofacial development. Genes coding the expression of growth factors, transcription factors and extracellular matrix molecules regulate this process. Tooth eruption through the dental follicle is a complex phenomenon. It involves osteoblastic and osteoclastic activity that contributes to form dentoalveolar bone. This bone formation and the development of dental occlusion, first for the deciduous, then for the succedaneous dentition, has a profound impact on the development of the lower part of the face. The mode of tooth eruption, guided by precise genetic control, is influenced by its neuromuscular environment and the response of the periodontal ligaments to the environment. Tooth positioning is altered by functional imbalance; as the periodontal ligament responds to forces and rapidly remodels the dentoalveolar complex in order to maintain the necessary physiological distance between the alveolar wall and the dental root.
Article
The purpose of this study was firstly to characterize the changes occurring in size and form of the mineralizing maxillary second primary molar and first permanent molar crowns, and secondly to determine if similar changes in size and form characterize enamel apposition in the crowns of these teeth. Twenty-five primary second molars and 20 maxillary permanent first molars at various stages of development, found in archaeological excavations in Israel, were examined for a number of measured variables using image analyser software. Teeth were divided into two groups according to their stage of development: stage I included all teeth at an early stage of development in which mesiobuccal-cusp height was less than 5 mm for the primary molar and 5.9 mm for the permanent molar; stage 2 included all teeth in later stages of development where mesiobuccal-cusp height was greater than these values. In the primary molar, a significant increase was found between the two stages in almost all variables. Significant correlations were also found between all intercusp distances and the external variables. Strong correlations between height of the mesiobuccal cusp and all external and internal variables were noted in stage 1, but fewer in stage 2. In the permanent tooth, no increase was observed in intercusp distances and very few correlations were found between and among the variables. The results suggest that a change in the shape of the maxillary primary second molar occurs during formation, with the lingual cusp tips moving lingually and distally, and the distobuccal cusp tips moving distally. No change occurs in the shape of the maxillary permanent first molar during crown formation. Growth of the maxillary primary second and permanent first molar crowns occurs in 'bursts' of development.
Article
Full-text available
Intercuspal distances and mesiodistal and buccolingual crown diameters of maxillary pre-molars were recorded from dental casts of 262 Australian Aboriginals. Although mesiodistal and buccolingual dimensions showed sexual dimorphism, no significant differences were noted between the sexes for intercuspal distances. Intercuspal dimensions showed greater variability and fluctuating asymmetry than did either of the traditional measures. No significant differences in heritability were noted among the three dimensions. Correlations between mesiodistal and buccolingual dimensions were higher than those between buccolingual and intercuspal measures. It appears that the sex differences, which are observed in overall crown dimensions, are established after the cusp tips are localized. Intercuspal distances appear to have a strong genetic component of variability, although they show high phenotypic variability and fluctuating asymmetry. Total tooth size may be subject to more intense selective pressures than the sites of initial calcification.
Article
Tooth size and morphology have been studied in 35 participants with trisomy G. The control material was obtained from 33 dental students. Special attention has been paid to the mean cusp pattern of the upper first and second molars. The classification matrix for the linear discriminant function analysis between participants with trisomy G and controls, based on five selected variables that determine the cusp pattern, showed three misclassifications.
Article
We measured the mesio-distal and bucco-lingual crown diameters of 13 males with the fra(X) or Martin-Bell syndrome. Fluctuating crown-size asymmetry was calculated and compared with values obtained in normal Caucasian children and also with a sample of 19 males with Down syndrome. A statistically significant increased asymmetry was found in the fra(X) males when compared to normal control individuals. In the maxilla, Down syndrome males showed a significantly higher tooth crown asymmetry than fra(X) males. (less than 0.02); in the mandible, no significant differences were found between the 2 groups. It is suggested that crown size asymmetry be included in the evaluation of fra(X) males.
Article
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Article
Peer Reviewed http://deepblue.lib.umich.edu/bitstream/2027.42/67554/2/10.1177_00220345700490033401.pdf
Article
Mean values and variances of the mesiodistal and buccolingual dimensions of all deciduous and permanent teeth, except third molars, were compared between 147 Down syndrome and 265 control subjects. Permanent tooth dimensions were significantly smaller in the Down syndrome group and also tended to show greater variability. However, for the deciduous dentition, some dimensions were significantly larger in Down syndrome and no systematic differences in variability were noted between the groups. These findings indicate that there may be an initial transitory acceleration in mitotic activity of developing enamel organs in Down syndrome followed by the characteristic generalized retardation in growth.
Article
Growth and development of hard tissues in Down syndrome is marked by retardation and increased phenotypic variability. Retardation in skeletal maturation and skeletal growth is most severe during early childhood. Skeletal maturation and growth during the circumpubertal years are associated in a normal way with other aspects of pubertal development. Various characteristics of dental development are abnormal in Down syndrome. The effect of the trisomic condition on dental eruption and teeth size is somewhat less severe than its effect on skeletal maturation and growth of stature. The concept of increased developmental instability in Down syndrome is discussed.
Article
The size and shape characteristics of permanent mandibular first molars were compared in a group of young males with Down syndrome (DS) and a control group of normal males. Generalized size was quantified by the log transforms of five intercusp distances and shape by a principal component analysis of the log distances scaled to constant size. On average the DS molars were smaller than the controls by 8%, the most marked reduction being in the distance between the distal and distolingual cusps. The scores on two of the four components of shape also differed between the DS and control teeth. These two shape components, which accounted for over 41% of the total shape variation, were determined specially by the occlusal morphology of the distal crown region. Discriminant function analyses also indicated the importance of the distal regions in discriminating between control and DS molars. Evidence suggests that trisomy 21 is associated with a general retardation in growth. The observed features of DS molars were consistent with decreased cellular activity in the developing tooth germs, producing morphological changes that were more pronounced in the later-forming crown regions.
Article
Subjects with Down syndrome provide a useful model for investigating the effect of chromosomal aneuploidy on developmental pathways. Studies suggest that a major effect of trisomy is a decrease in developmental stability. The present study examines fluctuating dental asymmetry in Down syndrome. Mesiodistal crown diameters were measured from dental casts of 114 Down syndrome subjects. Correlation coefficients for antimeric permanent teeth served as an index of dental asymmetry. These values were compared with normal values obtained from the literature. Fluctuating dental asymmetry is thought to reflect the relative success of developmental homeostasis in countering developmental disturbances. Down syndrome subjects have significantly increased dental asymmetry. In addition, they show a disproportionate increase in dental asymmetry for those teeth reported to have the least developmental stability. These results support the contention that the chromosomal imbalance in Down syndrome results in amplified developmental instability.
Article
Morphometric variables of second primary molar crowns from birth to completion were examined and measured. An image analysing technique comprising a photographic camera, a monitor, a computer with appropriate software and a digital caliper was used. Strong correlations were found between the 'external' aspect of the crown (mesiobuccal cusp height, mesiodistal and buccolingual dimensions and perimeter), and between all the 'occlusal' measurements of the crown, i.e. all the intercusp distances. However, poor correlations were found between the external and internal measurements of the crown such as the mesiobuccal cusp height and mesiobuccal-mesiolingual cusp-tip distance. It was also found that the mesiobuccal cusp serves as the apex of two triangles, the one formed by mesial cusps, and one formed by the distal cusps. The cusps on the mesial portion of the crown (ML, DB) are on a similar radius from the MB cusp, and the cusps on the distal portion are on a similar radius from the MB cusp. The small sample is a limitation but the results suggest a separate and independent pattern and rate of development of the external and the occlusal morphological variables of the tooth crown. Further research is needed on larger samples.
Size and shape in relation to growth and form. Symposia of the Zoological Society of London 46
  • Healey Mjr
  • Tanner Jm
HEALEY MJR, TANNER JM (1981) Size and shape in relation to growth and form. Symposia of the Zoological Society of London 46, 19-35.
Relation of human abnormalities of the dentition
  • Mcmillan Rs
MCMILLAN RS, KASHGARIAN M (1961) Relation of human abnormalities of the dentition. II. Mongolism. Journal of the American Dental Association 63, 368-373.
Increased crownsize asymmetry in the permanent dentition
  • Garn Sm
  • Cohen Mm
  • Geciauskas Ma
GARN SM, COHEN MM, GECIAUSKAS MA (1970a) Increased crownsize asymmetry in the permanent dentition. Journal of Dental Research 49, 465.