Reforma a la salud

*MDDr. Mariana RaszkovaÂ, **Mgr. Jana VrbkovaÂ, Ph.D.,*Doc. MUDr. PavlõÂna CÏernochovaÂ, Ph.D. *Ortodonticke oddeÏlenõÂ, Stomatologicka klinika FN u sv. Anny a LF MU v BrneÏ

*Department of Orthodontics, Clinic of Stomatology, University Hospital of St.Anne, Masaryk University Brno **Katedra matematicke analyÂzy a aplikacõ matematiky, PrÏF UP v Olomouci

**Department of mathematical analysis and applied mathematics, Faculty of Science, Palacky University Olomouc Souhrn

CõÂl studie: CõÂlem retrospektivnõ studie bylo zjistit, zda se u pacientuÊ s agenezõ hornõÂho staÂleÂho postrannõÂho rÏe- zaÂku hodnoty vyÂskytu dalsÏõÂch dentaÂlnõÂch anomaÂliõ signifikantneÏ lisÏõ od hodnot vyÂskytu teÏchto anomaÂliõ v populaci. MateriaÂl a metodika: Zkoumany soubor tvorÏilo 120 pacientuÊ s agenezõ hornõÂho staÂleÂho postrannõÂho rÏezaÂku. U teÏchto pacientuÊ byla sledovaÂna prevalence dvanaÂcti dentaÂlnõÂch anomaÂliõÂ, ktere se vyskytujõ v souvislosti s hy- podonciõÂ. ZjisÏteÏne prevalence byly srovnaÂny s referencÏnõÂmi hodnotami z populacÏnõÂch studiõÂ.

VyÂsledky: Ve zkoumaneÂm souboru byl ve srovnaÂnõ s beÏzÏnou populacõ zaznamenaÂn vysÏsÏõ vyÂskyt mikrodoncie hornõÂho staÂleÂho postrannõÂho rÏezaÂku, ageneze staÂlyÂch zubuÊ, ageneze trÏetõÂch molaÂruÊ, taurodontismu, palatinaÂlnõ retence hornõÂho staÂleÂho sÏpicÏaÂku, ektopicke erupce a impakce dolnõÂho staÂleÂho druheÂho molaÂru a distoangulace zaÂrodku dolnõÂho druheÂho premolaÂru. Naopak u hyperodoncie, syndromu kraÂtkyÂch korÏenuÊ, transpozice zubuÊ, ektopicke erupce hornõÂho staÂleÂho prvnõÂho molaÂru a infraokluze docÏasnyÂch molaÂruÊ nebyl zjisÏteÏn signifikantnõ rozdõÂl ve vyÂskytu oproti beÏzÏne populaci.

ZaÂveÏr: Vzhledem k vyÂsledkuÊm studie lze doporucÏit dlouhodobe sledovaÂnõ pacientuÊ s agenezõ hornõÂho staÂleÂho postrannõÂho rÏezaÂku s ohledem na vcÏasne zahaÂjenõ leÂcÏby prÏidruzÏenyÂch dentaÂlnõÂch anomaÂliõÂ(Ortodoncie 2013, 22, cÏ. 2, s. 91-105).

Abstract

Aims: Our retrospective study aimed to find out whether the occurrence of other dental anomalies in patients with missing maxillary permanent lateral incisor is significantly different from the overall occurrence of those ano- malies in the general population.

Material and method: The sample included 120 patients with missing maxillary permanent lateral incisor. The prevalence of twelve other dental anomalies associated with hypodontia was monitored in these patients. The values obtained were compared with reference values recorded in population studies.

Results: In the monitored sample of patients a higher prevalence of maxillary permanent lateral incisor mic- rodontia was found as well as permanent teeth agenesis, third molars agenesis, taurodontism, palatal impaction of maxillary permanent canine, ectopic eruption, impaction of lower permanent second molar, and distoangula- tion of lower second premolar germ. On the other hand, the prevalence of hyperodontia, short root syndrome, teeth transposition, ectopic eruption of maxillary permanent first molar, and infraocclusion of deciduous molars, was almost the same as in the rest of the population.

Introduction

In general, hypodontia refers to a dental anomaly that is characterized by a lower number of teeth, the germs of which are not developed. In case of an indivi- dual tooth we speak about agenesis or aplasia. In per- manent dentition hypodontia's prevalence oscillates between 2.2% and 10.1%. With the exception of third molars agenesis, the most frequently affected tooth is the lower second premolar, followed by upper lateral incisor and upper second premolar [1]. Depending on number and type of not established teeth patients suf- fer from functional and esthetic harm. Esthetic pro- blems arise mainly when agenesis affects anterior se- gment of dentition (i.e. upper permanent lateral incisor agenesis). The anomaly may be solved solely by an orthodontist [2] or in cooperation with an implantolo- gist [3] and an prosthodontist [4].

Hypodontia etiology is based on multiple factors. We can mention genetic factors and factors of the environment. It appears that genetic factors play the most important role. Genetic causes of agenesis have been revealed gradually thanks to the studies of affec- ted families, twins, and candidate genes. As the cau- ses of isolated (non-syndrome) form of hypodontia mutations in genes PAX9, MSX1 and AXIN2 were iden- tified. So far 5 mutations of MSX1 gene, 11 mutations of PAX9 gene, and 2 mutations of AXIN2 gene connec- ted with hypodontia were found [5]. In spite of substan- tial development in this area of research the genes re- sponsible for mild forms of hypodontia have not been determined yet. This holds also true about missing upper permanent lateral incisor.

Hoffmeister [6, 7, 8] was one of the first experts who recognized the common origin of structurally different developmental anomalies of dentition (including hypo- dontia). He introduced the concept of ªmicrosymp- toms of genetically determined predisposition to de- fective development of dentitionª, and recommended to observe these microsymptoms as signals of poten- tial occurrence of hyperodontia, germ dystopia, or hy- podontia in a patient and their relatives. A number of works prove that hypodontia is not an isolated pheno- menon but that it is related to number, size, morpho- logy, mineralisation and eruption of other teeth in den- tition [9, 10, 11, 12]. Markova and VaÂsÏkova state that hypodontia should be seen not as a mere anomaly in the number of teeth, but as a manifestation of abnor- Conclusion: With regard to the study results we recommend a long-term follow-up of the patients with mis- sing maxillary permanent lateral incisor with respect to the potential early treatment of associated dental anoma- lies(Ortodoncie 2013, 22, No. 2, p. 91-105).

KlõÂcÏova slova: ageneze, hypodoncie, dentaÂlnõ anomaÂlie Key words: agenesis, hypodontia, dental anomaly

UÂvod

TermõÂn hypodoncie obecneÏ oznacÏuje dentaÂlnõ ano- maÂlii, jejõÂzÏ podstatou je primaÂrneÏ snõÂzÏeny pocÏet zubuÊ, jejichzÏ zaÂrodky nejsou vyvinuty. V prÏõÂpadeÏ, zÏe se nevy- tvorÏil jednotlivy zub, hovorÏõÂme o jeho agenezinebo aplaÂzii. Prevalence hypodoncie ve staÂleÂm chrupu se pohybuje mezi2,2 a 10,1 %. S vyÂjimkou ageneze trÏe- tõÂch molaÂruÊ, je nejcÏasteÏjipostizÏenyÂm staÂlyÂm zubem dolnõ druhy premolaÂr, naÂsledovany hornõÂm postrannõÂm rÏezaÂkem a hornõÂm druhyÂm premolaÂrem [1]. V zaÂvislosti na pocÏtu a typu nezalozÏenyÂch zubuÊ je pacient v ruÊzne mõÂrÏe posÏkozen funkcÏneÏ i esteticky. Estetika je naru- sÏena zejmeÂna pokud se jedna o agenezive frontaÂlnõÂm uÂseku chrupu, jako je tomu v prÏõÂpadeÏ ageneze hornõÂho staÂleÂho postrannõÂho rÏezaÂku. RÏesÏenõ teÂto vady pak muÊzÏe byÂt pouze ortodonticke [2] nebo ve spolupraÂci s implantologem [3] cÏiprotetikem [4].

Etiologie hypodoncie je multifaktoriaÂlnõÂ. UplatnÏujõ se faktory geneticke a faktory prostrÏedõÂ. Faktory gene- ticke majõ prÏi vzniku hypodoncie zrÏejmeÏ rozhodujõÂcõ roli. Geneticke pozadõ agenezõ je postupneÏ odhalo- vaÂnodõÂkystudiupostizÏenyÂchrodin, dvojcÏat akandidaÂt- nõÂch genuÊ. Jako prÏõÂcÏina izolovane (nesyndromoveÂ) formy hypodoncie byly identifikovaÂny mutace v ge- nech PAX9, MSX1 a AXIN2. Dosud bylo nalezeno 5 mutacõ genu MSX1, 11 mutacõ genu PAX9 a 2 mu- tace genu AXIN2 spojenyÂch s hypodonciõ [5]. I prÏes zaÂsadnõ rozvoj teÂto oblastivyÂzkumu zuÊstaÂvajõ geny zodpoveÏdne za lehcÏõ formy hypodoncie neodhaleny. TyÂka se to iageneze hornõÂho staÂleÂho postrannõÂho rÏe- zaÂku.

JednõÂm z prvnõÂch, kterÏõ rozpoznalispolecÏny gene- ticky puÊvod strukturaÂlneÏ velmiodlisÏnyÂch vyÂvojovyÂch poruch dentice vcÏetneÏ hypodoncie byl Hoffmeister [6, 7, 8]. Zavedl pojem ¹mikrosymptomy geneticky de- terminovane predispozice k porusÏeneÂmu vyÂvojiden- ticeª a doporucÏil sledovaÂnõ teÏchto mikrosymptomuÊ coby signaÂluÊ mozÏneÂho vyÂskytu hyperodoncie, dysto- pie zaÂrodkuÊ nebo hypodoncie u pacienta a jeho prÏõÂbu- znyÂch. DuÊkazy o tom, zÏe hypodoncie nenõ izolovanyÂm jevem, ale ma vztah k pocÏtu, velikosti, morfologii, mi- neralizaci a erupci ostatnõÂch zubuÊ v dentici, podaÂvajõ praÂce imnoha dalsÏõÂch autoruÊ [9, 10, 11, 12]. Markova a VaÂsÏkova uvaÂdeÏjõÂ, zÏe na hypodoncii je trÏeba pohlõÂzÏet nikoli jako na pouhou anomaÂlii pocÏtu zubuÊ, ale v sÏi rsÏõÂm slova smyslu jako na jeden z projevuÊ anomaÂlnõÂho vyÂ- voje zubnõ lisÏty a zubuÊ z nõ vznikajõÂcõÂch [13]. Do vyÂcÏtu

mal development of dental lamina and teeth origina- ting there [13]. The dental anomalies associated with hypodontia include: reduction of mesiodistal width of all teeth, microdontia of upper permanent lateral inci- sor, short root syndrome, taurodontia, palatally impac- ted upper permanent canine, teeth transposition, ectopic eruption of teeth and expressive inclination of dental germs, teeth rotation, infraocclusion of deci- duous molars, late dental development and late erup- tion of teeth, defects of hard dental tissues.

Our retrospective study focuses on the specific type of hypodontia - agenesis of upper permanent lateral in- cisor. The anomaly can be diagnosed as early as bet- ween the age of 8 and 9, when this tooth usually erupts. The aim of our study was to determine whether pa- tients with missing upper permanent lateral incisor show higher prevalence of other dental anomalies (in comparison with the general population), and whether agenesis of upper permanent lateral incisor may serve as an early warning signal (risk factor) of potential occurrence of other dental anomalies.

Material and methods

The retrospective study examined orthodontic re- cords of 120 Caucasians (mean age 15.1 years, ± 7.3) with unilateral or bilateral agenesis of upper per- manent lateral incisor, patients of the Department of Orthodontics, Clinic of Stomatology of St.Anne's Ho- spital in Brno, and the private practice of MUDr. JirÏõÂ Tvardek, between 2005-2012. The following criteria were adopted: unilateral or bilateral agenesis of upper permanent lateral incisor proved by clinical and radio- logical examination, without possible extractions, wi- thout prior orthodontic treatment, available complete diagnostic data obtained through anamnesis and clini- cal examination, orthodontic documentation models, good quality standard OPG. Patients with syndromes and/or clefts in the orofacial area were excluded from the sample, because higher prevalence of dental ano- malies are typical for them. The age of patients was between 6 and 43 years. The sample included 45 ma- les (mean age 14.2 years, ± 6.1), and 75 females (mean age 15.6 years, ± 7.9), the proportion of males to fema- les was 1 : 1.67.

In OPGs (sometimes supplemented by an intraoral x-ray or CT examination) and in orthodontic documen- tary models of each patient in the sample, the following dental anomalies were diagnosed according to defi- ned diagnostic criteria:

1. Microdontia of upper permanent lateral incisor 2. Agenesis of permanent teeth (except third molars),

agenesis of upper and lower second premolar was assessed individually

3. Third molars agenesis dentaÂlnõÂch vad, u kteryÂch byl pozorovaÂn spolecÏny vyÂ-

skyt s hypodonciõÂ, patrÏõÂ: redukce mesiodistaÂlnõ sÏõÂrÏky vsÏech zubuÊ, mikrodoncie hornõÂho staÂleÂho postrannõÂho rÏezaÂku, syndrom kraÂtkyÂch korÏenuÊ, taurodontismus, palatinaÂlneÏ retinovany hornõ staÂly sÏpi cÏaÂk, transpozice zubuÊ, ektopicka erupce zubuÊ a vyÂrazne inklinace zub- nõÂch zaÂrodkuÊ, rotace zubuÊ, infraokluze docÏasnyÂch mo- laÂruÊ, opozÏdeÏny dentaÂlnõ vyÂvoj a opozÏdeÏne prorÏezaÂvaÂnõ zubuÊ, poruchy tvrdyÂch zubnõÂch tkaÂnõÂ.

Tato retrospektivnõ studie se zameÏrÏila na konkreÂtnõ typ hypodoncie - agenezi hornõÂho staÂleÂho postrannõÂho rÏezaÂku. Jedna se o anomaÂlii, kterou lze diagnostikovat jizÏ mezi8-9 rokem veÏku, kdy tento zub nejcÏasteÏjipro- rÏezaÂvaÂ. CõÂlem bylo zjistit, zda majõ pacienti s agenezõ hornõÂho staÂleÂho postrannõÂho rÏezaÂku ve srovnaÂnõ s beÏzÏ- nou populacõ vysÏsÏõ vyÂskyt dalsÏõÂch dentaÂlnõÂch vad a zda muÊzÏe ageneze staÂleÂho hornõÂho postrannõÂho rÏezaÂku slouzÏit jako vcÏasny varovny signaÂl (rizikovy faktor) mo- zÏneÂho vyÂskytu jinyÂch dentaÂlnõÂch anomaÂli õÂ.

MateriaÂl a metodika

Retrospektivnõ studie zkoumala dokumentaci 120 jedincuÊ bõÂle rasy (pruÊm. veÏk 15,1 let, ± 7,3) s jednostran- nou nebo oboustrannou agenezõ staÂleÂho hornõÂho po- strannõÂho rÏezaÂku, kterÏõ bylievidovaÂnijako pacienti OrtodontickeÂho oddeÏlenõ Stomatologicke kliniky u sv. Anny v BrneÏ a privaÂtnõ ortodonticke praxe MUDr. JirÏõÂho Tvardka mezilety 2005-2012. Vstupnõ kriteÂria pro zarÏa- zenõ pacienta do studie byla naÂsledujõÂcõÂ: jednostranna nebo oboustranna ageneze staÂleÂho hornõÂho postran- nõÂho rÏezaÂku potvrzena klinickyÂm a radiologickyÂm vysÏe- trÏenõÂm s vyloucÏenõÂm mozÏnostiextrakce, zÏaÂdna prÏed- chozõ ortodonticka leÂcÏba, dostupne uÂplne diagno- sticke uÂdaje zõÂskane anamneÂzou a klinickyÂm vysÏetrÏenõÂm, ortodonticke dokumentacÏnõ modely, kva- litnõ standardizovany ortopantomogram (OPG). Ze stu- die byli vyrÏazenipacientise syndromy a rozsÏteÏpy v oro- faciaÂlnõ oblasti, u kteryÂch je vysÏsÏõ vyÂskyt dentaÂlnõÂch anomaÂliõ typickyÂ. VeÏkove rozpeÏtõ pacientuÊ bylo 6-43 let. V souboru bylo 45 muzÏuÊ (pruÊm. veÏk 14,2 let, ± 6,1) a 75 zÏen (pruÊm. veÏk 15,6 let, ± 7,9), pomeÏr muzÏi:- zÏeny byl tedy 1 : 1,67.

Na OPG snõÂmcõÂch (v neÏkteryÂch prÏõÂpadech doplneÏ- nyÂch iintraoraÂlnõÂm snõÂmkem nebo CT vysÏetrÏenõÂm) a na ortodontickyÂch dokumentacÏnõÂch modelech kazÏ- deÂho pacienta ze souboru byly diagnostikovaÂny na zaÂ- kladeÏ prÏesneÏ definovanyÂch diagnostickyÂch kriteÂriõÂ naÂ- sledujõÂcõÂ dentaÂlnõÂ anomaÂlie:

1. mikrodoncie staÂleÂho hornõÂho postrannõÂho rÏezaÂku, 2. ageneze staÂlyÂch zubuÊ (kromeÏ trÏetõÂch molaÂruÊ),

zvlaÂsÏt' hodnocena ageneze hornõÂho a dolnõÂho dru- heÂho premolaÂru,

3. ageneze trÏetõÂch molaÂruÊ,

4. Supernumerary teeth (hyperodontia) 5. Short root syndrome (short root anomaly) 6. Taurodontia

7. Palatally impacted upper permanent canine 8. Teeth transposition

9. Ectopic eruption of upper permanent first molar 10. Ectopic eruption and impaction of lower perma-

nent second molar

11. Distoangulation of lower second premolar germ 12. Infraocclusion of deciduous molars

Prevalence of individual dental anomalies in the sample of patients with missing upper lateral incisors was compared with reference values for the general population. Reference values were derived from com- prehensive population studies. In the case of several studies the criteria for the selection were a number of patients in the sample, Caucasian or European popu- lation, and consistent diagnostic criteria.

All patients with missing upper lateral incisors came from orthodontic departments. The orthodontic popu- lation does not represent the common - non-selected - population, and therefore the prevalence of specific dental anomalies is higher in orthodontic patients than in the rest of the population. In the case of anomalies where the data for orthodontic patients was accessi- ble, the prevalence found in patients with missing upper lateral incisors was compared with these values. In all cases two-sided tests were used - i.e. binomial tests - the correspondence of prevalences was tested against a two-sided alternative (the prevalence may have been higher as well as lower). The frequency of a given anomaly in the sample of patients with missing upper lateral incisors (prevalence estimation) was compared with reference prevalence values given in per cents. The prevalence estimation is calculated as the estimation of a binomial differentiation parameter. In results there is given both point estimation and 95% confidence interval (CI). The results are presented as P-value. Statistically significant differences are on the level of significance of 5% (P-value < 0.05).

Diagnostic criteria of dental anomalies used in the study

OPGs, sometimes also occlusal radiographs, peria- pical radiographs and results of CT examinations were evaluated visually during diagnostics of dental anoma- lies. To evaluate the prevalence of dental anomalies vi- sual assessment and measurements of orthodontic models with a caliper ruler were used.

The diagnostic criterion of microdontia was the comparison of mesiodistal width of upper lateral inci- sor and mesiodistal width of lower lateral incisor. If the parameter was identical or smaller, the incisor was diagnosed as microdontic. In the case that the microdontic incisor had normal crown morphology, it 5. syndrom kraÂtkyÂch korÏenuÊ,

6. taurodontismus,

7. palatinaÂlneÏ retinovany hornõ staÂly sÏpi cÏaÂk, 8. transpozice zubuÊ,

9. ektopicka erupce staÂleÂho hornõÂho prvnõÂho molaÂru, 10. ektopicka erupce a impakce staÂleÂho dolnõÂho dru-

heÂho molaÂru,

11. distoangulace zaÂrodku druheÂho dolnõÂho premo- laÂru,

12. infraokluze docÏasnyÂch molaÂruÊ.

VyÂskyt jednotlivyÂch dentaÂlnõÂch vad v souboru pa- cientuÊ s agenezõ hornõÂch lateraÂlnõÂch rÏezaÂkuÊ byl srovnaÂn s referencÏnõÂmihodnotamipro beÏzÏnou populaci. Jako referencÏnõ hodnoty byly zvoleny vyÂsledky rozsaÂhlyÂch populacÏnõÂch studiõÂ. Pokud bylo k dispozici võÂce popu- lacÏnõÂch studiõÂ, byl vyÂbeÏrovyÂm kriteÂriem pocÏet pacientuÊ v souboru, bõÂla nebo evropska populace a shodna diagnosticka kriteÂria.

VsÏichni pacienti s agenezõÂhornõÂch lateraÂlnõÂch rÏezaÂkuÊ byli pacienty z ortodontickyÂch praxõÂ. Ortodonticka po- pulace nereprezentuje beÏzÏnou neselektovanou popu- lacia lze prÏedpoklaÂdat, zÏe prevalence urcÏi tyÂch dentaÂl- nõÂch vad je u ortodontickyÂch pacientuÊ vysÏsÏõÂnezÏ v beÏzÏne populace. U anomaÂliõÂ, kde byla data pro ortodonticke pacienty k dispozici, byly zjisÏteÏne prevalence pacientuÊ s agenezõÂhornõÂch lateraÂlnõÂch rÏezaÂkuÊ srovnaÂny i s teÏmito hodnotami.

Ve vsÏech prÏõÂpadech srovnaÂvaÂnõ prevalence anomaÂ- liõ byl pouzÏit oboustranny typ testu - test binomickyÂ, tj. testovala se shoda prevalencõ oprotioboustranne al- ternativeÏ (prevalence mohla byÂt vysÏsÏõ inizÏsÏõÂ). Pozoro- vana cÏetnost dane anomaÂlie v souboru pacientuÊ s age- nezõ hornõÂch lateraÂlnõÂch rÏezaÂkuÊ (odhad prevalence) se porovnaÂvala s referencÏnõ prevalencõ v procentech. Od- had prevalence se pocÏõÂta jako odhad parametru bino- mickeÂho rozdeÏlenõÂ. Ve vyÂsledcõÂch je uveden bodovy odhad i95% konfidencÏnõ interval (CI). VyÂsledky jsou prezentovaÂny jako P-hodnota. Statisticky vyÂznamneÏ odlisÏne jsou vyÂsledky na hladineÏ vyÂznamnosti5 % (P-hodnota < 0,05).

Diagnosticka kriteÂria dentaÂlnõÂch anomaÂliõ pouzÏita ve studii

PrÏi diagnostice dentaÂlnõÂch anomaÂliõ byly vizuaÂlneÏ hodnoceny OPG snõÂmky pacienta, prÏõÂp. iskusove snõÂmky, intraoraÂlnõ snõÂmky a vyÂsledky CT vysÏetrÏenõÂ. K hodnocenõ vyÂskytu dentaÂlnõÂch vad bylo vyuzÏito take vizuaÂlnõÂhodnocenõÂa meÏrÏenõÂortodontickyÂch dokumen- tacÏnõÂch modeluÊ posuvnyÂm meÏrÏidlem.

DiagnostickyÂm kriteÂriem mikrodoncie bylo srovnaÂnõ mesiodistaÂlnõ sÏõÂrÏky hornõÂho postrannõÂho rÏezaÂku s me- siodistaÂlnõ sÏõÂrÏkou dolnõÂho postrannõÂho rÏezaÂku. Byl-li tento rozmeÏr stejny nebo mensÏõÂ, byl rÏezaÂk diagnostiko- vaÂn jako mikrodontickyÂ. Pokud meÏl mikrodonticky rÏe- zaÂk normaÂlnõ morfologii korunky, byl oznacÏen jako

was considered as a small upper lateral incisor. In the case the incisor had a conical shape, it was referred to as a peg lateral [14].

The agenesis of a tooth was considered when it was missing in the dental arch, the case history made it clear that it had not been extracted, and OPG did not show the tooth in the relevant calendar age of a patient. In individual types of teeth the different beginning of mineralization of a germ was taken into account. In ca- ses of second premolar and third molar we can see va- riable beginning of mineralization. On average, second premolar mineralization starts at the age of 3-3.5 years, however, it may even start many years later [1]. There- fore, agenesis of second premolar was diagnosed at the age of 10 and later, agenesis of third molars at the age of 14 and later.

In case of short root syndrome we monitored only upper permanent first incisors with the finished root development. Radiographs with blurred teeth con- tours or radiographs biased due to substantial crow- ding were eliminated from the evaluation. Teeth in which the crown contour was distorted due to caries, injury or expressive abrasion were also eliminated. Short root anomaly (SRA) was represented by cases in which the proportion root/crown (R/C ratio) was £ 1.0 in both upper central incisors [15]. The measure- ment method by HoÈlttaÈ et al was adopted (Fig. 1) [16]. Taurodontia was monitored in first and second per- manent molars in both jaws with the finished root de- velopment. Diagnostic criteria proposed by Shiftman and Chanannel were used [17]. According to these cri- teria, taurodonta is diagnosed when:

Distance A-B

Distance A-Apex³ 0.2 mm,

and at the same time the distance B-CEJ ³ 2.5 mm, where A is the most occlusal point of pulp cavity, B is the most apical point of pulp cavity, Apex is the most apical point on the longest root, and CEJ is cemento- enamel junction.

Palatally impacted upper permanent canine was diagnosed in children at the age of 10 or older. OPGs and occlusal radiographs were evaluated with parallax maly hornõ postrannõ rÏezaÂk. MeÏl-lirÏezaÂk kuzÏelovity (koÂ-

nickyÂ) tvar, byl oznacÏen jako cÏõÂpkovity [14].

PrÏihodnocenõ ageneze zubuÊ, byl urcÏi ty typ zubu oznacÏen jako nezalozÏenyÂ, pokud chybeÏl v zubnõÂm ob- louku, z anamneÂzy vyplyÂvalo, zÏe nebyl extrahovaÂn a na OPG snõÂmku nebyl zub prÏõÂtomny v prÏõÂslusÏneÂm kalen- daÂrÏnõÂm veÏku pacienta. Pro jednotlive typy zubuÊ byl zo- hledneÏn odlisÏny pocÏaÂtek mineralizace zubnõÂho zaÂ- rodku. S veÏtsÏõ variabilitou zahaÂjenõ mineralizace se muÊ- zÏeme setkat u druheÂho premolaÂru a trÏetõÂho molaÂru. PruÊmeÏrneÏ zacÏõÂna mineralizace druheÂho premolaÂru ve 3-3,5 letech, ale muÊzÏe byÂt zahaÂjena io mnoho let po- zdeÏji[1]. Ageneze druheÂho premolaÂru byla proto u pa- cientuÊ diagnostikovaÂna ve veÏku 10 a võÂce let. Ageneze trÏetõÂch molaÂruÊ ve veÏku 14 a võÂce let.

U syndromu kraÂtkyÂch korÏenuÊ byly sledovaÂny pouze staÂle hornõ prvnõ rÏezaÂky s dokoncÏenyÂm vyÂvojem ko- rÏene. Z hodnocenõ byly vyrÏazeny rentgenove snõÂmky, na kteryÂch byla kontura zubuÊ neostra nebo zkreslena vlivem velkeÂho steÏsnaÂnõÂ. DaÂle byly vyrÏazeny zuby,