anomalies dentaires chez une population portugaise

Original articleArticle original

� 2013 CEOPublished by / Edite par Elsevier Masson SAS

All rights reserved / Tous droits reserves

Dental anomalies in a Portuguesepopulation

Anomalies dentaires chez une populationportugaise

Maria Dolores CAMPOYa, Ana GONZ�ALEZ-ALLOb, Joaquim MOREIRAc,Josep USTRELLd, Teresa PINHOe,*,

aDepartment of Orthodontics, University of Murcia, Hospital Morales Meseguer, 2a planta,C/Marqu�es de los V�elez s/n, Murcia, Murcia 30008, SpainbDepartment of Orthodontic Post-graduate Program, University of Valencia, Av. de VicenteBlasco Ib�a~nez, 13, 46010 Valencia, SpaincDepartment of Odontopediatrics, Instituto Superior de Ciencias da Sa�ude-Norte/CESPU,Centro de Investigac~ao Ciencias da Sa�ude (CICS), rua Central de Gandra, 1317, 4585-116Gandra, PRD, PortugaldDepartment of Orthodontics, Faculty of Dentistry, University of Barcelona, Feixa Llarga,s/n - 08907 L’Hospitalet Ll, SpaineDepartment of Orthodontics, Instituto Superior de Ciencias da Sa�ude-Norte/CESPU, Centrode Investigac~ao Ciencias da Sa�ude (CICS), rua Central de Gandra, 1317, 4585-116 Gandra, PRD,Portugal

Available online: 27 March 2013 / Disponible en ligne : 27 mars 2013

SummaryObjective: The aim of this study was to evaluate the prevalenceand pattern of agenesis, supernumerary teeth, impacted teethand transpositions, as well as the relation between them, in aPortuguese sample.

Material and methods: The study sample consisted of 2888patients, observed between 2005 and 2009 at the DentistryClinic of the Instituto Superior de Ciencias da Sa�ude-Norte(ISCSN, Portugal). The study included evaluation of the fol-lowing parameters: agenesis of all teeth, supernumerary teeth,impacted permanent teeth and tooth transposition. The agerange varied from 7 to 21 years. In order to study the absenceof the third molar, subjects aged below 14 years were excluded.Statistical analysis was performed using SPSS�.

Results: Excluding third molars, the prevalence of tooth agen-esis, supernumerary teeth, impacted teeth and transpositions

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R�esum�e

Objectif : Le but de cette �etude �etait d’�evaluer, chez un�echantillon portugais, la pr�evalence et la distribution desag�en�esies, des dents surnum�eraires, des dents incluses etdes transpositions dentaires, aussi bien que la relation entreces diff�erentes anomalies.Mat�eriaux et m�ethodes : L’�echantillon comprenait 2888patients, observ�es entre 2005 et 2009 a la clinique de dentist-erie de l’Instituto Superior de Ciencias da Sa�ude-Norte(ISCSN, Portugal). L’�etude comprenait l’�evaluation des para-m�etres suivants : ag�en�esie de toutes les dents, dents sur-num�eraires, dents permanentes incluses et transpositionsde dents. L’age des sujets s’�echelonnait de sept a 21 ans.Pour l’�etude portant sur l’absence de la troisi�eme molaire,les sujets ag�es de moins de 14 ans ont �et�e exclus.L’analyse statistique a �et�e r�ealis�ee a l’aide de SPSS�.R�esultats : En excluant les troisi�emes molaires, la pr�evalencede l’ag�en�esie dentaire, des dents surnum�eraires, des dents

*Correspondence and reprints / Correspondance et tir�es a part.

e-mail address / Adresse e-mail :

[email protected], [email protected] (Teresa Pinho)

International Orthodontics 2013 ; 11 : 210-220doi:10.1016/j.ortho.2013.02.007

mailto: [email protected]

http://dx.doi.org/10.1016/j.ortho.2013.02.007

Dental anomalies in a Portuguese populationAnomalies dentaires chez une population portugaise

was 6.1%, 0.8%, 1.8% and 0.2%, respectively, for thisPortuguese population. There was a significantly higher prev-alence of supernumerary teeth in males than in females(P < 0.05). The mesiodens was the most frequent supernumer-ary tooth, the upper canine was the most frequent impactedtooth, and the upper canine and upper lateral were the two mostfrequently transposed teeth. There was a significantly higherprevalence of missing third molars in the impacted canine groupthan in the non-impacted canine group (P < 0.05).

Conclusions: Agenesis is the most frequent dental anomaly.There are no differences between genders, except for supernu-merary teeth, which are found more frequently in men. A rela-tion between third molar agenesis and impacted canines wasfound.� 2013 CEO. Published by Elsevier Masson SAS. All rightsreserved

Key-words

·Hypodontia.
·Tooth agenesis.
·Supernumerary.
·Impacted teeth.
·Transposition.
·Frequency.
Introduction

Developmental dental anomalies can be classified in: toothposition anomalies, teeth number anomalies, tooth shapeanomalies and tooth size anomalies [1]. Of all of them, hypo-dontia is the most common [2]. It is interesting to determinewhether there is a connection among them. In that context,various studies have tried to establish such a relation,although the results have not always agreed.K€uchler et al. [3] found that tooth agenesis increased the riskof infra-occlusion of primary molars in cases with premolaragenesis and the risk of double formation of primary incisorsin cases with lower incisor agenesis. In contrast, tooth agen-esis, taurodontism and microdontia were not associated withsupernumerary teeth. However, in a previous study performedat the Instituto Superior de Ciencias da Sa�ude-Norte (ISCSN,Portugal), a relation between unilateral agenesis of the max-illary lateral incisor and microdontia of the contralateral wasfound [4]. This discovery led orthodontists to suppose thatmicrodontia of the maxillary lateral incisors may represent adifferent expression of the molecular changes leading to thedevelopment of agenesis of the maxillary lateral incisors,which should therefore be paid special attention when drawing

International Orthodontics 2013 ; 11 : 210-220

incluses et des transpositions �etait, respectivement, de 6,1 %,0,8 %, 1,8 % et 0,2 % dans cet �echantillon de la populationportugaise. La pr�evalence de dents surnum�eraires �etait sig-nificativement plus �elev�ee chez les hommes que chez lesfemmes (p < 0,05). La m�esiodens �etait la dent surnum�erairela plus fr�equente, la canine sup�erieure la dent incluse la plusfr�equente, et la canine sup�erieure et la lat�erale sup�erieure lesdeux dents les plus fr�equemment transpos�ees. La pr�evalencede troisi�emes molaires absentes �etait significativement plus�elev�ee dans le groupe avec une canine incluse que dans legroupe sans canine incluse (p < 0,05).Conclusions : L’ag�en�esie est l’anomalie dentaire la plusfr�equente. Il n’existe pas de diff�erences entre les sexes, a l’ex-ception des dents surnum�eraires, que l’on observe plusfr�equemment chez les hommes. Une relation entre l’ag�en�esiede la troisi�ememolaire et les canines incluses a �et�e observ�ee.� 2013 CEO. Edite par Elsevier Masson SAS. Tous droitsreserves

Mots-cl�es

·Hypodontie.
·Ag�en�esie dentaire.
·Surnum�eraire.

·Dents incluses.

·Transposition.
·Fr�equence.
Introduction

Les anomalies du d�eveloppement dentaire peuvent etreclass�ees en : anormalit�e de la position, du nombre, de laforme et de la taille des dents [1]. Parmi toutes ces anomalies,la plus courante est l’hypodontie [2]. Il serait int�eressant, parailleurs, de d�eterminer s’il existe une relation entre elles. Dansce contexte, diverses �etudes ont cherch�e a �etablir une tellerelation mais les r�esultats n’ont pas toujours concord�e.K€uchler et al. [3] ont trouv�eque l’ag�en�esie dentaire augmentaitle risque d’infraclusion des molaires temporaires chez lessujets pr�esentant une ag�en�esie des pr�emolaires et accentuaitle risque d’une double formation des incisives temporaireschez les individus avec une ag�en�esie des incisives inf�erieures.En revanche, l’ag�en�esie dentaire, le taurodontisme et lamicro-dontie n’affichaient pas de relation avec les dents sur-num�eraires. Cependant, dans une �etude pr�ec�edente r�ealis�eea l’Instituto Superior de Ciencias da Sa�ude-Norte (ISCSN,Portugal), un lien entre l’ag�en�esie unilat�erale de l’incisivelat�erale maxillaire et la microdontie de la controlat�erale a �et�eobserv�e [4]. Cette d�ecouverte a amen�e les orthodontistesa supposer que la microdontie des incisives lat�erales maxil-laires puisse repr�esenter une expression diff�erente des

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Maria Dolores CAMPOY et al.

up the clinical diagnosis or taking the family history, both ofwhich can lead us to suspect tooth agenesis [5].

Nevertheless, other authors evaluating the probability andpattern of maxillary canine impaction in relation to anomalousadjacent lateral incisors found no positive association betweenlateral incisor anomalies and maxillary canine impaction [6].

It is worth highlighting the study of Peck et al. [7] of anorthodontic population in which they relate canine positionanomalies with different agenesis patterns. Thus, a palatallydisplaced canine and mandibular lateral incisor-canine trans-position are associated with agenesis of at least one thirdmolar. Upper canine-first premolar transposition is associatedwith upper lateral incisor agenesis, and lower second premolaragenesis has a high frequency in the three anomalous positionsof the canine (palatally displaced canine, mandibular lateralincisor-canine transposition and upper canine-first premolartransposition). Papadopoulos et al. [8], on the other hand,found in a meta-analysis that tooth transposition is an isolatedphenomenon. The aim of this retrospective study was to eval-uate the prevalence and pattern of agenesis, supernumeraryteeth, impacted teeth and transpositions in the permanentdentition, and the relation among them, in a Portuguesesample.

Material and methods

The research was performed on material from the clinical filesof the Dentistry Clinic of the ISCSN, using 20,976 panoramicradiographs, taken between 2005 and 2009. The patients wereaged between 7 and 21 years.

The radiographs were analyzed by two trained observers whofollowed a pre-established protocol. Radiographs showingrecent extractions, bone defects, evidence of surgery, traumaand fractures were excluded. The files of patients with devel-opmental anomalies such as ectodermal dysplasia, cleft lip orpalate, Down’s syndrome, or who had undergone previousorthodontic treatment were also excluded from the study.Hence, a total of 2888 patients’ panoramic radiographs ofsufficient quality were selected.

The study included investigation of the following parameters:all teeth ageneses, supernumerary teeth, impacted permanentteeth and tooth transposition:

— tooth agenesis was considered when the tooth was not in thearch and there was no history of extraction;

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changements mol�eculaires aboutissant au d�eveloppement del’ag�en�esie des incisives lat�erales maxillaires a laquelle il fau-drait porter une attention toute particuli�ere au moment de lapose du diagnostic clinique ou de la prise de l’anamn�esefamiliale, qui peuvent, toutes les deux, nous amenera soupconner la pr�esence de l’ag�en�esie dentaire [5].N�eanmoins, d’autres auteurs ont �evalu�e la probabilit�e et ladistribution de l’inclusion des canines maxillaires en relationavec des incisives lat�erales adjacentes anormales et n’onttrouv�e aucune association positive entre les anomalies desincisives lat�erales et l’inclusion des canines maxillaires [6].Il est int�eressant de souligner l’�etude de Peck et al. [7] sur unepopulation orthodontique ou ils d�ecrivent une relation entre lesanomalies de position de canines et de diff�erents typesd’ag�en�esies. Ainsi, une canine en ectopie palatine et la trans-position entre une incisive lat�erale et une canine mandibu-laires sont associ�ees a l’ag�en�esie d’au moins une troisi�ememolaire. La transposition entre une canine et une premi�eremolaire maxillaires est associ�ee a l’ag�en�esie des lat�eralesmaxillaires, et l’ag�en�esie des deuxi�emes pr�emolaires mandi-bulaires pr�esente une fr�equence �elev�ee dans les trois posi-tions anormales de la canine (canine en ectopie palatine,transposition d’une lat�erale et d’une canine mandibulaireset transposition d’une canine et d’une premi�ere pr�emolairemaxillaire). D’un autre cot�e, Papadopoulos et al. [8], dansune m�eta-analyse, ont conclu que la transposition dentaireest un ph�enom�ene isol�e. Le but de cette �etude r�etrospective�etait d’�evaluer la pr�evalence et la distribution de l’ag�en�esie,des dents surnum�eraires, des dents incluses et des transposi-tions dentaires dans la denture permanente, ainsi que la rela-tion entre ces anomalies, dans une population portugaise.

Mat�eriel et m�ethodes

Cette �etude a �et�e r�ealis�ee a partir de donn�ees contenues dansles dossiers cliniques de la clinique dentaire de l’ISCSN,notamment sur 20 976 radiographies panoramiques prisesentre 2005 et 2009. Les patients �etaient ag�es entre sept et21 ans.Les radiographies ont �et�e analys�ees par deux observateursform�es qui ont suivi un protocole pr�e�etabli. Les radiographiesmontrant des extractions r�ecentes, des d�efauts osseux, dessignes de chirurgie, de traumatismes et de fractures ont �et�eexclues. Les dossiers de patients montrant des anomalies dud�eveloppement telles que la dysplasie ectodermique, lesfentes labiales ou palatines et la trisomie 21 ou de patientsayant d�eja recu un traitement orthodontique ont �et�e exclus del’�etude. En tout, 2888 radiographies panoramiques de qualit�esuffisante ont �et�e retenues.L’�etude comprenait une analyse des param�etres suivants : lesag�en�esies affectant toutes les dents, les dents surnum�eraires,les dents permanentes incluses et les transpositionsdentaires :— l’ag�en�esie dentaire �etait d�efinie comme l’absence d’unedent a l’arcade sans histoire d’extraction ;



— supernumerary tooth was defined as an extra tooth, eruptedor unerupted;— impacted tooth was defined as a tooth not expected to eruptbased on clinical and radiographic assessment [9];

— tooth transposition was defined as an unusual type ofectopic eruption where a permanent tooth develops in theposition normally occupied by another permanent tooth [10].

In doubtful cases, confirmation was obtained from a clinicalfile.In order to study the absence of the third molar, an analysiswas performed excluding subjects aged under 14 years.Previous studies refer to this age as being the approximatelimit for the appearance of the third molar germs [11]. Wedivided this new sample into an impacted canine group (withat least one impacted canine) and a non-impacted caninegroup (with no impacted canine).The material collected comprised 1399 male patients and1489 females, respectively, 48.4% and 51.6% of the sample.The mean age was 14.06 W 4.21 years.

Statistical analysis was performed using the SPSS� statisticalsoftware package (version 15.0 for Windows). Differences inthe pattern of hypodontia, supernumerary teeth, impactedpermanent teeth and tooth transposition according to gender,involvement of right and left sides, and upper and lower archeswere evaluated using a non-parametric Chi2 test. A value ofP < 0.05 was considered significant.

Results

Agenesis

Excluding third molars, 175 subjects (6.1%) from a total of2888 presented tooth agenesis. [12]

Supernumerary teeth

From the 2888 patients in the sample, a total of 27 (4 females,23 males) supernumerary teeth were observed, in 24 (0.8%)patients (4 females and 20 males), with a statistically signif-icant difference between genders (P < 0.05). Of these 24patients, 22 (91.7%) had one supernumerary tooth, one patient(4.2%) had two supernumerary teeth and another (4.2%) hadthree.Supernumerary teeth were observed bilaterally in one patientand in 23 patients unilaterally, with a statistically significantdifference (P < 0.05).Of the 27 supernumerary teeth, we found 21 in the upper arch:a mesiodens was observed in nine (33.3%) cases, three(11.1%) cases were observed in the area of the lateral incisors(between central and lateral incisors), three (11.1%) in thecanine region (between lateral and canine), one (3.7%) in the


— une dent surnum�eraire �etait d�efinie comme une dent addi-tionnelle, �emerg�ee ou non �emerg�ee ;— une dent incluse �etait d�efinie comme une dent dontl’�eruption �etait jug�ee improbable au vu des �evaluations clini-que et radiographique [9] ;— une transposition dentaire �etait d�efinie comme une formed’�eruption ectopique inhabituelle ou une dent permanente sed�eveloppe a la position normalement occup�ee par une autredent permanente [10].En cas de doute, nous avons cherch�e confirmation dans ledossier clinique.Pour l’�etude de l’absence d’une troisi�eme molaire, les sujetsag�es de moins de 14 ans ont �et�e �ecart�es. Des �etudesant�erieures ont indiqu�e cet age comme marquant la limiteapproximative de l’apparition des germes des troisi�emesmolaires [11]. Nous avons divis�e ce nouvel �echantillon en deuxsous-groupes : un groupe avec au moins une canine incluseet un groupe sans canines incluses.Le mat�eriel recueilli comprenait 1399 patients de sexemascu-lin et 1489 de sexe f�eminin, soit, respectivement, 48,4 % et51,6 % de l’�echantillon. L’age moyen �etait de14,06W 4,21 ans.L’analyse statistique a �et�e r�ealis�ee a l’aide du logiciel statis-tique SPSS� (version 15.0 pour Windows). Les diff�erencesd’incidence entre l’hypodontie, les dents surnum�eraires, lesdents permanentes incluses et la transposition dentaire enfonction du sexe, l’implication des cot�es droit et gauche etdes arcades sup�erieure et inf�erieure ont �et�e �evalu�ees a l’aided’un test Khi2 non param�etrique. Une valeur de p < 0,05 �etaitconsid�er�ee comme significative.

R�esultats

Ag�en�esie

En excluant les troisi�emes molaires, 175 sujets (6,1 %) sur untotal de 2888 ont pr�esent�e une ag�en�esie dentaire [12].

Dents surnum�eraires

Sur les 2888 patients dans l’�echantillon, nous avons relev�e untotal de 27 dents surnum�eraires (4 filles, 23 garcons) chez 24patients (4 filles et 20 garcons) avec une diff�erence statistique-ment significative entre les sexes (p < 0,05). Sur ces 24patients, 22 (91,7 %) avaient une seule dent surnum�eraire,un patient (4,2 %) avait deux surnum�eraires et un patient(4,3 %) en avait trois.Des dents surnum�eraires ont �et�e observ�ees bilat�eralementchez un patient et unilat�eralement chez 23 patients, avecune diff�erence statistiquement significative (p < 0,05).Sur les 27 dents surnum�eraires, nous en avons trouv�e 21a l’arcade sup�erieure : unem�esiodens a �et�e observ�ee en neufcas (33,3 %). Trois cas (11,1 %) ont �et�e relev�es dans la r�egiondes incisives lat�erales (entre les incisives centrale et lat�erale),trois cas (11,1 %) dans la r�egion des canines (entre la lat�erale

213


premolar region (between two premolars) and five (18.5%) inthe third molar region. In the lower arch, we found six super-numerary teeth: two (7.4%) in the incisor region, three(11.1%) in the premolar region, and one (3.7%) in the molarregion (between first and second molar).The rate of supernumerary teeth was higher in the maxilla(n = 21, 77.8%) than in the mandible (n = 6, 22.2%).Due to the fact that 40% of the supernumerary teeth weremesiodens and lower incisors, which are in the midline, dif-ferences between right and left sides were not evaluated(Table I).

Impacted teeth

Of the 2888 patients, the number with impacted teeth was 52(1.8%), 26 females and 26 males, with a total of 69 impactedteeth. Of these 52 patients, 41 (78.8%) had one impactedtooth, eight (15.4%) had two impacted teeth, two patients(3.8%) had three and one (1.9%) had six impacted teeth.Impacted teeth were observed bilaterally in six patients andunilaterally in 46, with a statistically significant difference(P < 0.05).Of the 69 impacted teeth, the most common positions were theupper canine (n = 40, 58.0%), followed by the upper secondpremolar (n = 7, 10.1%), the upper central incisor (n = 6,8.7%), the upper second molar (n = 5, 7.2%), the upper lateralincisor (n = 4, 5.8%), the lower second molar (n = 3, 4.3%),the lower canine (n = 2, 2.9%), the upper first premolar (n = 1,1.4%) and upper first molar (n = 1, 1.4%). The incidence of

able Irequency of supernumerary teeth based on gender.

Tableau IFr�equence de dents surnum�eraires en fonction du sexe dessujets.

upernumerary/Surnum�eraire Female/Femme

Male/Homme

Total P-values

n % n % n %

aw/Machoires Maxilla/Maxillaire 3 14.3 18 85.7 21 77.8 .01*

Mandible/Mandibule 1 16.7 5 83.3 6 22.2 .102

pper arch/Arcade sup�erieure Mesiodens 2 22.2 7 77.8 9 33.3 .096

Lateral area/Secteur lat�eral 1 33.3 2 66.7 3 11.1 .564

Canine region/R�egion canine 0 .0 3 100.0 3 11.1 –

Premolar area/Secteur pr�emolaire 0 .0 1 100.0 1 3.7 –

3rd molar area/Secteur 3esmolaires 0 .0 5 100.0 5 18.5 –

ower arch/Arcade inf�erieure Incisive area/Secteur incisif 0 .0 2 100.0 2 7.4 –

Premolar area/Secteur pr�emolaire 1 33.3 2 66.7 3 11.1 .564

Molar area/Secteur molaire 0 .0 1 100.0 1 3.7 –

P-values indicate difference between males and females.

TF

S

J

U

L

*

Les valeurs p indiquent la diff�erence entre sujets males et femelles.

214

et la canine), un (3,7 %) dans la r�egion des pr�emolaires (entreles deux pr�emolaires) et cinq (18,5 %) dans la r�egion destroisi�emesmolaires et un (3,7 %) dans la r�egionmolaire (entrela premi�ere et la deuxi�eme molaire).

La fr�equence des dents surnum�eraires �etait plus �elev�ee aumaxillaire (n = 21, 77,8 %) qu’a la mandibule (n = 6, 22,2 %).Du fait que 40 % des dents surnum�eraires �etaient desm�esiodens ou des incisives inf�erieures, situ�ees donc pr�es dela ligne m�ediane, les diff�erences entre cot�e droit et cot�egauche n’ont pas �et�e �evalu�ees (Tableau I).

Les dents incluses

Sur les 2888 patients, 52 (1,8 %) avaient au moins une dentincluse (26 filles et 26 garcons) pour un total de 69 dentsincluses. Sur ces 52 patients, 41 (78,8 %) avaient une seuledent incluse, huit (15,4 %) avaient deux dents incluses, deux(3,8 %) en avaient trois et un (1,9 %) en avait six.Des dents incluses ont �et�e observ�ees bilat�eralement chez sixpatients et unilat�eralement chez 46, avec une diff�erence sta-tistiquement significative (p < 0,05).Sur les 69 dents incluses, les positions les plus fr�equentes�etaient : la canine sup�erieure (n = 40, 58,0 %), suivie de ladeuxi�eme pr�emolaire sup�erieure (n = 7, 10,1 %), l’incisivecentrale sup�erieure (n = 6, 8,7 %), la deuxi�eme molairesup�erieure (n = 5, 72 %), l’incisive lat�erale sup�erieure (n = 4,58 %), la deuxi�ememolaire inf�erieure (n = 3, 4,3 %), la canineinf�erieure (n = 2, 2,9 %), la premi�ere pr�emolaire sup�erieure


Table IIFrequency of included teeth based on gender.

Tableau IIFr�equence de dents incluses en fonction du sexe des sujets.

Included teeth/Dents incluses Female/Femme

Male/Homme

Total P-values

n % n % n %

Jaw/Machoire Maxilla/Maxillaire 31 48.4 33 51.6 64 88.9 .803

Mandible/Mandibule 3 60.0 2 40.0 5 6.9 .655

Side/Cot�e Right/Droit 14 45.2 17 54.8 31 43.1 .590

Left/Gauche 20 52.6 18 47.4 38 52.8 .746

Teeth/Dents Upper canine/Canine maxillaire 20 50.0 20 50.0 40 58.0 1.000

Upper 2nd premolar/2epr�emolaire sup�erieure 4 57.1 3 42.9 7 10.1 .705

Upper central incisor/Incisive centrale sup�erieur 2 33.3 4 66.7 6 8.7 .414

Upper second molar/2emolaire sup�erieure 3 60.0 2 40.0 5 7.2 .655

Upper lateral incisors/Incisives lat�erales sup�erieures 0 .0 4 100.0 4 5.8 –

Lower 2nd molar/2emolaire inf�erieure 2 66.7 1 33.3 3 4.3 .564

Lower canine/Canine inf�erieure 1 50.0 1 50.0 2 2.9 1.00

Upper 1st premolar/1repr�emolaire sup�erieure 1 100.0 0 .0 1 1.4 –

Upper 1st molar/1remolaire sup�erieure 1 100.0 0 .0 1 1.4 –

P-values indicate difference between males and females.Les valeurs p indiquent la diff�erence entre sujets males et femelles.


impacted teeth was higher in the maxilla (n = 64, 88.9%) thanthe mandible (n = 5, 6.9%) with a statistically significantdifference (P < 0.05) and on the left side (n = 38, 52.8%)versus the right side (n = 31, 43.1%) (Table II).

Transpositions

Of the 2888 patients, six (0.2%) had transpositions, threefemales and three males.Of the six transpositions, five (83.3%) displayed the inversionbetween the upper left lateral incisor and the upper leftcanine, and only one (16.7%) was between the lower leftsecond premolar and the lower left second molar.

The transposition frequency was higher in the maxilla (n = 5,83.3%) than in the mandible (n = 1, 16.7%) and only on theleft side (n = 6, 100%) (Table III).

Relationship among the variables evaluated in thestudy

No relationship was found between supernumerary teeth andagenesis, between supernumerary and impacted teeth,


(n = 1, 1,4 %) et la premi�eremolaire sup�erieure (n = 1, 1,4 %).L’incidence de dents incluses �etait plus �elev�ee au maxillaire(n = 64, 88,9 %) qu’a la mandibule (n = 5, 6,9 %) avec unediff�erence statistique significative (p < 005) et du cot�egauche (n = 38, 52,8 %) versus le cot�e droit (n = 31, 43,1 %)(Tableau II).

Transpositions

Sur les 2888 patients, six (0,2 %) avaient des transpositions,trois filles et trois garcons.Sur ces six transpositions, cinq (83,3 %) pr�esentaient uneinversion de l’incisive lat�erale gauche sup�erieure et la caninegauche sup�erieure et un seul (16,7 %) entre la deuxi�emepr�emolaire gauche inf�erieure et la deuxi�eme molaire gaucheinf�erieure.La fr�equence des transpositions �etait plus �elev�ee aumaxillaire(n = 5, 83,3 %) par rapport a la mandibule (n = 1, 16,7 %) etdu seul cot�e gauche (n = 6, 100 %) (Tableau III).

Les relations entre les variables �evalu�ees dans cette�etude

Aucune relation n’a �et�e trouv�ee entre les dents surnum�eraireset l’ag�en�esie, entre les dents surnum�eraires et les dents

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Table IIIFrequency of types of teeth affected by transpositions based ongender.

Tableau IIIFr�equence des types de dents affect�ees par les transpositionsen fonction du sexe des participants.

Transpositions/Transpositions Female/Femme

Male/Homme

Total P-values

n % n % n %

Jaw/Machoire Maxilla/Maxillaire 2 40.0 3 60.0 5 83.3 .655

Mandible/Mandibule 1 10.0 0 .0 1 16.7 –

Side/Cot�e Right/Droit 0 .0 0 .0 0 .0 –

Left/Gauche 3 5.0 3 5.0 6 100.0 1.000

Teeth/Dents Upper left lateral incisor and canine/Canine et incisive lat�erale gauche

2 4.0 3 6.0 5 83.3 0.655

Lower left 2nd premolar and second molar/2epr�emolaire et 2emolaire inf�erieures gauches

1 10.0 0 .0 1 16.7 –

P-values indicate difference between males and females.Les valeurs p indiquent la diff�erence entre sujets males et femelles.


between supernumerary and transposed teeth, between agen-esis and impacted teeth, or between agenesis and tooth trans-position. Curiously, in two patients we found a relationshipbetween maxillary left lateral incisor and upper left caninetransposition and impacted teeth on the right side.

A statistically significant correlation (P < 0.05) was foundbetween impacted canines and third molar agenesis(r = 0.056). Of the 2888 patients, 1605 were aged between14 and 21 years. Of these, 307 (19.1%) had a minimum of onemissing third molar [12], 297 (18.9%) from the non-includedcanine group (a total of 1575) and 10 (33.3%) from theimpacted canine group (30 in all). There was a significantlyhigher prevalence of missing third molars in the impactedcanine group than in the non-impacted canine group(P < 0.05).

Discussion

It is not easy to choose an appropriate sample to examine thefrequency of anomalies. The ideal situation would be a randomsample of the general population, but that is very controversialfrom the radiological point of view. Because of this, the sourceof information has to be a dental practice, with the inevitablebias this entails.

The contrasting results among studies may arise from racialdifferences and differences in the methodology used.

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incluses, entre les dents surnum�eraires et les dents trans-pos�ees, entre l’ag�en�esie et les dents incluses ou entrel’ag�en�esie et la transposition dentaire. Curieusement, chezdeux patients, nous avons relev�e une relation entre l’incisivelat�erale gauche maxillaire et la transposition de la caninegauche sup�erieure et les dents incluses du cot�e droit.Une corr�elation statistiquement significative (p < 0,05) a �et�etrouv�ee entre les canines incluses et l’ag�en�esie des troisi�emesmolaires (r = 0,056). Sur les 2888 patients, 1605 �etaient ag�esentre 14 et 21 ans. Parmi ceux-ci, 307 (19,1 %) avaient aumoins une troisi�eme molaire absente [12], 297 (18,9 %) dansle groupe sans canine incluse (1575 patients en tout) et dix(33,3 %) dans le groupe avec canine incluse (30 patients entout). Il y avait une pr�evalence significativement plus �elev�ee detroisi�emes molaires manquantes dans le groupe avec canineincluse par rapport au groupe sans canine incluse (p < 0,05).

Discussion

Il n’est pas facile de choisir un �echantillon appropri�e pourl’analyse de la fr�equence des anomalies. Dans l’id�eal, il fau-drait recruter un �echantillon randomis�e de la populationg�en�erale mais cette technique est tr�es controvers�ee pourdes raisons radiologiques. En cons�equence, la seule sourced’information demeure le cabinet du dentiste avec le biaisin�evitable que cela comporte.Les r�esultats contrast�es des diverses �etudes peuvent s’expli-quer par les diff�erences ethniques ainsi que par lesdiff�erences de m�ethodologie employ�ee.



Of all the dental anomalies analyzed in this study, agenesis isthe most frequent, followed by impacted teeth, supernumerar-ies and, finally, transpositions.

Agenesis

Agenesis was present in 6.1% of our population and, as men-tioned above, represents the most frequent anomaly. Thispercentage concords with that found by other authors [2].

Supernumerary teeth

The frequency of supernumerary teeth in our study was 0.8%.These data concord with those found in the literature wherethe reported prevalence of supernumerary teeth variesbetween 0.1 and 3.8% of the population [13–16]. Pinho andPollmann, in the same population, found a frequency of 0.76%of supernumerary teeth [17].Many studies have found a higher prevalence of supernumer-ary teeth among males [15,18,19]. These findings concordwith the present study.In terms of location, our results indicated that most of thesupernumerary teeth were mesiodens. Many authors in theliterature found the same result [13,16,18]. However, Lutensuggested that upper lateral incisors were the most frequentsupernumeraries [15].

The majority of supernumerary teeth were found in the pre-maxilla region, followed by the third molar region, the lateralincisor region (between central and lateral incisor) and thecanine region (between lateral and canine) and, finally, thepremolar region (between two premolars). In the lower arch,the order was: the premolar region, the incisor region and themolar region (between first and second molar). In 1967, Lutenproposed the following decreasing frequency: upper lateralincisors, mesiodens, upper central incisors followed by pre-molars [15]. Fardi et al. [16] reported a different sequence for apopulation in Northern Greece: mesiodens, mandibular pre-molar region, molar region and maxillary lateral incisorregion.

Impacted teeth

We found that the upper canines were the most commonlyimpacted teeth, which concords with other studies [16].However, the rarity of impacted canines in the mandible(two in all) was confirmed in the present study [16,20–22].

Premolar impaction is rare. In our study, we found maxillarysecond premolars to be the teeth most frequently impactedfollowed by the upper first premolars. However, Roberts-Harry and Sandy [23] showed that first upper premolars wereimpacted more frequently. Fardi et al. [16] reported that lowersecond premolars were the most frequently impacted teeth,


Parmi toutes les anomalies analys�ees dans cette �etude,l’ag�en�esie est la plus fr�equente, suivie par les inclusions, lesdents surnum�eraires et les transpositions dentaires.

L’ag�en�esie

L’ag�en�esie �etait pr�esente chez 6,1 % de notre population et,comme nous le mentionnons ci-dessus, elle constitue l’anom-alie la plus fr�equente. Ce pourcentage s’accorde avec lesr�esultats trouv�es par d’autres auteurs [2].

Les dents surnum�eraires

La fr�equence de dents surnum�eraires dans notre �etude �etaitde 0,8 %. Ces donn�ees concordent avec celles qu’on trouvedans la litt�erature ou la pr�evalence des dents surnum�erairesvarie entre 0,1 et 3,8 % de la population [13–16]. Pinho etPollmann, dans lameme population, ont trouv�e une fr�equencede dents surnum�eraires de 0,76 % [17].Beaucoup d’�etudes ont trouv�e une pr�evalence plus �elev�ee dedents surnum�eraires parmi des sujets masculins [15,18,19].Ce r�esultat concorde avec notre propre �etude.En ce qui concerne la position dentaire, nos r�esultats indiquentque la plupart des dents surnum�eraires �etaient desm�esiodens. Beaucoup d’auteurs dans la litt�erature ont trouv�ele meme r�esultat [13,16,18]. Cependant, Luten a sugg�er�e queles dents surnum�eraires les plus fr�equemment observ�ees�etaient les incisives lat�erales sup�erieures [15].La majorit�e des dents surnum�eraires se trouvaient dans lar�egion pr�emaxillaire, suivie des r�egions suivantes : troisi�emesmolaires, incisives lat�erales (entre centrale et lat�erale),canines (entre lat�erale et canine) et, enfin, pr�emolaires (entredeux pr�emolaires). A l’arcade inf�erieure, l’ordre des r�egions�etait : pr�emolaires, incisives et molaires (entre la premi�ere etla deuxi�eme molaire). En 1967, Luten a propos�e la fr�equenced�ecroissante suivante : incisives lat�erales sup�erieures,m�esiodens, incisives centrales sup�erieures suivies despr�emolaires [15]. Fardi et al. [16] ont rapport�e une s�equencediff�erente pour une population en Gr�ece septentrionale :m�esiodens, r�egion des pr�emolaires sup�erieures, r�egionmolaire et r�egion des incisives lat�erales maxillaires.

Les dents incluses

Dans notre �etude, les canines sup�erieures �etaient les dentsles plus fr�equemment incluses, ce qui concorde avec lesr�esultats d’autres auteurs [16]. Cependant, la raret�e decanines incluses a la mandibule (deux en tout) a �et�e confirm�eepar la pr�esente �etude [16,20–22].Les pr�emolaires incluses sont rares. Dans notre �etude, nousavons trouv�e que les deuxi�emes pr�emolaires maxillaires�etaient les plus fr�equemment incluses, suivies des premi�erespr�emolaires sup�erieures. Cependant, Roberts-Harry et Sandy[23] ont montr�e que les premi�eres molaires sup�erieures�etaient plus fr�equemment incluses. Fardi et al. [16] ont

217


followed by maxillary second premolars. All this demonstratesthe great variability regarding their prevalence.

The literature contains very rare cases of molar impaction[16,24], as confirmed by the low incidence found in this study.We observed higher percentages in females than in males.Some studies suggested a genetic component to impactedmolars [16,24].

Transpositions

Our results agree with others found in the literature [25–28],which reports that tooth transposition is a rare occurrenceaffecting less than 1% of the population (in our case, 0.2%of our sample).We observed that transposition affects the maxillary dentition(83.3%) more frequently than the mandibular dentition(16.7%), which concurs with other studies [29–31].

The most common type of transposition described in the liter-ature involves the maxillary canine and the first premolar[9,26,28]. Maxillary canine-lateral incisor transposition isreported to be the second most common type. However, wefound this last transposition to be the most common. Thefindings of Celikoglu et al. agree with the present study [32].

Transpositions were more common on the left side as opposedto the right side. Again, Celikoglu et al. [32] reported the samefindings.It has been hypothesized that the etiology of maxillary canine-lateral incisor transposition is more environmental thangenetic [33]. Dentofacial trauma in the deciduous dentition,with subsequent drifting of the developing permanent teeth, isthe most common etiologic factor [25,31]. There are fewreports of familial occurrence or dental anomalies associatedwith maxillary canine-lateral incisor transpositions [34]. Itseems that the only dental anomaly associated with maxillarycanine-lateral incisor transposition is increased third molaragenesis [7], a relationship we did not find.

Relation among variables evaluated in the study

The only relationship we found was a statistically significantcorrelation between impacted canines and third molar agen-esis. There was a significantly higher prevalence of missingthird molars in the impacted canine group than in the non-impacted canine group. We did not find such a relationship inthe literature.

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rapport�e que les deuxi�emes pr�emolaires inf�erieures �etaientles dents les plus fr�equemment incluses, suivies des deux-i�emes pr�emolaires maxillaires. Tous ces r�esultats montrent lagrande variabilit�e concernant la pr�evalence de ces dentsincluses.La litt�erature fait �etat de tr�es rares cas d’inclusions molaires[16,24], ce que confirment les r�esultats de notre �etude. Nousavons observ�e des pourcentages plus �elev�es chez les fillesque chez les garcons. Certaines �etudes ont sugg�er�e l’exis-tence d’une composante g�en�etique aux molaires incluses[16,24].

Transpositions

Nos r�esultats concordent avec ceux trouv�es dans la litt�erature[25–28], qui rapportent que la transposition dentaire est unph�enom�ene rare affectant moins de 1 % de la population(0,2 % dans notre �echantillon).Nous avons observ�e que la transposition touche la denturemaxillaire (83,3 %) plus souvent que les dents mandibu-laires (16,7 %), ce qui est en accord avec d’autres �etudes[29–31].La forme de transposition la plus fr�equente d�ecrite dans lalitt�erature concerne la canine et la premi�ere pr�emolaire max-illaire [9,26,28]. Les transpositions canine–incisive lat�eralemaxillaires seraient la deuxi�eme forme la plus fr�equente.Cependant, nous avons trouv�e que cette derni�ere transposi-tion �etait la plus fr�equente. Les r�esultats de Celikoglu et al.concordent avec ceux de la pr�esente �etude [32].Les transpositions �etaient plus fr�equentes du cot�e gauche quedu cot�e droit. Encore une fois, Celikoglu et al. ont rapport�e desr�esultats identiques.Il a �et�e sugg�er�e que l’�etiologie de la transposition canine–incisive lat�erale rel�eve plus de l’environnement que de lag�en�etique [33]. Les traumatismes dentofaciaux des dentstemporaires, avec d�erive subs�equente des dents perma-nentes en voie de formation, sont le facteur �etiologique le plusfr�equent [25,31]. Peu de cas familiaux n’ont �et�e rapport�es nid’anomalies dentaires associ�ees a des transpositions descanines et des lat�erales maxillaires [34]. Il semblerait que laseule anomalie dentaire associ�ee a la transposition canine–lat�erale maxillaires soit une augmentation de la fr�equence desag�en�esies des troisi�emes molaires [7], une relation que nousn’avons pas observ�ee.

Relations entre les variables �evalu�ees dans cette�etude

La seule relation que nous ayons d�ecouverte �etait une corr�ela-tion statistiquement significative entre les canines incluses etl’ag�en�esie d’une troisi�eme molaire. Il y avait une pr�evalencesignificativement plus �elev�ee d’absences de troisi�emesmolaires dans le groupe avec canine incluse que dans legroupe sans canine incluse. Nous n’avons pas trouv�e une tellerelation dans la litt�erature.



Disclosure of interest

The authors declare that they have no conflicts of interestconcerning this article.

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