Analiza razvoja i okluzalne karakteristike u primarnoj denticiji kod ispitanika sa i bez zbijenosti trajnih zubi

The fact that crowding appears in a larger number of cases for the first time during the replacement of teeth does not exclude the possibility o f an earlier appearance o f certain indicators, on the basis of which a future malocclusion could be predicted. In order to verify the stated hypothesis we decided to extract the factors which could be relevant to the development of crowding by means of analysis o f qualitative and quantitative characteristics o f primary dentition and by means of the evaluation o f the influence o f each individual feature on the spatial conditions in permanent dentition. The sample consisted o f 76 examinees o f both sexes which were longitudinally surveyed throughout eight years. For each examinee the following characteristics were registered and evaluated: existence o f primatical diastemas in the lower jaw, degree o f abrasion, existence and degree o f physiological diastemas in the upper jaw, condition o f equidistal planes, sagital interrelation determined by canines, overbite, transversal interrelation and overjet. After 8 years the examinees were divided into the group with crowding (51) and the group without crowding (25). The data were processed by the SAS software, for each group individually and compared mutually. The established hypothesis regarding the existence o f early symptoms relevant to the emergence o f crowding of permanent teeth has received only partial confirmation in the conducted survey. From the findings analyzed it follows that the appearance o f crowding is in the relation with the lack o f physiological diastemas; the absence or early closure o f the primatical diastema; the early loss o f equidistal plane and caries or extraction o f primary teeth. A more favorable prognosis in preventing the appearance o f crowding can be assigned to bigger physiological diastemas, the persistence of equidistal planes, the presence of primatical diastemas and intact primary teeth.Činjenica da se kompresija u većem broju slučajeva prvi put pojavljuje za vrijeme mjene zubi, ne isključuje mogućnost ranije pojave određenih indikatora, na temelju kojih bi se mogla predvidjeti buduća anomalija. S ciljem provjere navedene hipoteze odlučili smo odrediti faktore koji bi mogli biti relevantni za razvoj kompresije i to analizom kvalitativnih i kvantitativnih karakteristika mliječne denticije i evaluacijom utjecaja svakog pojedinog obilježja na prostorne uvjete u trajnoj denticiji. Uzorak se sastojao od 76 ispitanika oba spola koji su longitudinalno praćeni kroz osam godina. Svakom ispitaniku vrednovane su slijedeće karakteristike: postojanje primatnih dijastema u donjoj čeljusti, stupanj abrazije, postojanje i stupanj fizioloških dijastema u gornjoj čeljusti, stanje ekvidistalne ravnine, sagitalni odnos određen na očnjacima, dubina prijeklopa, transverzalni odnos i incizalna stepenica. Nakon osam godina ispitanici su podijeljeni u grupe sa (51) i bez kompresije (25), provedena je gnatometrijska analiza, a dobi-veni rezultati obrađeni su SAS programskom podrškom za svaku grupu posebno te međusobno uspoređeni. Hipoteza o postojanju ranih simptoma koji bi bili važni za nastanak kompresije u trajnoj denticiji samo je djelomično potvrđena ovom studijom. Analizom rezultata slijedi da je pojava kompresije povezana s nepostojanjem fizioloških dijastema, odsutnošću ranog zatvaranja primatnih dijastema, ranim gubitkom ekvidistalne ravnine, te karijesom i ekstrakcijom mliječnih zubi. Bolja prognoza može se očekivati ako su prisutne veće fiziološke dijasteme, ako perzistira ekvidistalna ravnina, ako postoje primatne dijasteme i ako su mliječni zubi intaktni

Dentoalveolar Characteristics in Subjects with Anterior Open Bite

Svrha ovoga rada bila je utvrditi izraženost dentoalveolarnih kompenzatornih mehanizama u ispitanika s otvorenim zagrizom u usporedbi s eugnatim ispitanicima. Ispitivanje je provedeno na 37 latero-lateralnih rentgenkefalograma pacijenata s otvorenim zagrizom i na 35 eugnatih ispitanika u dobi od 15 do 18 godina. Svaki rentgenkefalogram iscrtan je dva puta od dvaju autora. Rentgenkefalometrijska raščlamba sastojala se od mjerenja angularnih i linearnih parametara. Angularne varijable bile su: n-s-gn, sp-pm:mgo, m-go-ar, suma kuteva prema Bjorku, 1:sp-pm i 1:m-go. Linearne varijable oi, om, oi/om, ui, um, i ui/um uzete su iz Korkhausove analize. Statistička raščlamba obuhvatila je deskriptivnu statistiku, metodsku pogrešku, t-test i Pearsonov koeficijent korelacije. Statistički znatne razlike (p<0,001) između ispitivanih skupina pronađene su kod svih ispitivanih varijabli osim 1:sp-pm, oi/om i um. Pronađena je retruzija donjih sjekutića, što upućuje na dentoalveolarnu adaptaciju na postojeću posteriornu rotaciju čeljusti. Inklinacija gornjih inciziva je u odnosu prema bazi maksile u znatnoj negativnoj korelaciji s varijablom n-s-gn, i u laganoj negativnoj korelaciji s varijablom sppm: m.go. Varijable visine gornje i donje čeljusti (oi, om, ui, um) u znatnoj su međusobnoj korelaciji. Znatna negativna korelacija pronađena je između varijabli um i m-go-ar. Korelacija između varijable um i Bjorkova poligona lagana je i negativna. Varijabla ui pokazuje laganu negativnu korelaciju s varijablom m-go-ar. Takav odnos rezultat je kompenzatorne retruzije donjih inciziva na strmu mandibularnu ravninu.The purpose of this study was to determine the frequency and extent of dentoalveolar compensation in subjects with disharmonious vertical jaw base relationships, in relation to subjects with normal occlusion. The study was performed on 37 lateral cephalograms of patients with open bite and 35 of patients with normal occlusion, aged 15 to 18 years. Each cephalogram was traced twice by two authors. The cephalometric analyses were performed by linear and angular measurements. The angular cephalometric variables were: n-s-gn, sp-pm:m-go, m-go-ar, the sum of the posterior angles according to Bjork (1947, 1954,1966,1972),1:sp-pm and 1:m-go. Linear cephalometric variables: oi, om oi/om, ui, um and ui/um were analysed using the methods of Korkhaus (1959). Statistical data analysis included descriptive statistics, method error, t-test and Pearson(s correlation coefficient for association between variables. Significant differences (p < 0.001) between the samples were found in all investigated variables except 1:sp-pm, oi/om and um. Retrusion of the lower incisors was found, indicating dentoalveolar adaptation to the present posterior rotation of the mandible. Inclination of the upper incisors in relation to the base of the maxilla was significantly negative correlated with the variable n-s-gn, and slightly negatively by correlated with the variable sp:pmm-go. The variables of the height of the upper and lower jaws (oi, om, ui, um) were significantly correlated. A significiant negative correlation was found between variables um and m-go-ar. The correlation between variable um and Bjork’s polygon was slightly negative. The variable ui showed slight negative correlation with the variable m-go-ar. Such a relationship is the result of compensatory retrusion of the lower incisors and a steep mandibular plane

Sources for the History of Biomechanics

Biomaheniku možemo odrediti kao znanost koja zakone mehanike primjenjuje u rješavanju biologijskih probelma proučavajući mehanička svojstva bioloških organizama, sustava organa ili tkiva.Biomeahnička se istraživanja rabe u svim granama medicine. Povijest biomehanike nije moguće odijeliti od povijesnoga razvoja mehanike, a niti od razvoja biologije i medicine u cjelini.Biomechanics may be defined as a science which applies the laws o f mechanics in solving biological problems, through studying mechanical characteristics o f biological organisms, systems of organs or tissues. Biomechanical research is used in all medical fields. The history of bimechanics cannot be viewed separately from the historic development o f mechanics or from overall development o f biology and medicine

Spring Activator - a New Appliance in Skeletal Open Bite Treatment

Prikazan je novi tip ortodontske naprave, opružni aktivator po Sanderu za tretman ortodontskih nepravilnosti s vertikalnim tipom rasta. Opružni aktivator kao funkcionalna čeljusnoortopedska naprava djeluje putem funkcionalnih adaptacijskih mehanizama, što je omogućeno točnom lokalizacijom momenta i smjera sila koje proizvode ugrađene opruge kao i žvačni mišići. Djeluje direktno ne samo na razini dentoalveolarnih odnosa, nego i skeletnih struktura. Zbog toga se može smatrati pouzdanom i djelotvornom napravom u tretmanu skeletnog otvorenog zagriza.»Spring activator« according to Sander, a new removable orthodontic appliance for treatment o f vertical growth malocclusions is presented. Appliance acts through functional adapted mechanism with exact localization of force direction and moment which are produced by springs and masticatory muscles. Acting o f this appliance is directly on dentoalveolar and skeletal structures. Spring activator is a reliable appliance for treatment o f skeletal open bite

Dentometrijske karakteristike ispitanika s primarnom kompresijom

A comparative study of dentometric characteristics of incisors in the upper and lower jaws was performed in on attempt to determine the role of the size of the mentioned teeth in the process of primary crowding. The study included 200 examinees (140 females and 60 males) with primary crowding and 100 eugnathic subjects (48 females and 52 males) as a control group. The sample was selected according to the following criteria: anterior crowding, completed exchange of teeth, neutral intermaxillary relationship (Angle class I), lack of other malocclusion. The age was limited to 14 years in order to avoid the possible influence of tertiary crowding. The study was carried out by means of a sliding-caliper with 1 mm precision on plaster casts of the upper and lower jaws, and the mesiodistal diameters of all the four permanent incisors in the upper and lower jaws were measured. After statistical analysis and interpretation of the results, the following was concluded: Arithmetical means of the sums of the upper incisors were considerably higher in boys, while the difference between the mean values of the sums of the lower incisors was insignificant. The subjects with crowding had significantly bigger upper but not lower incisors. One of the important factors for the occurrence of crowding were bigger incisors, especially the upper central ones, and in girls also the lower incisors. The size of the incisors should by no means be taken as the only cause o f crowding, as demonstrated by the analysis of the widths and heights o f the upper dental arch. Significantly smaller widths of dental arches in the premolar and molar regions, along with an increase in the anterior upper height were registered in the subjects with crowding. The analysis of correlations revealed only a slight association between the size o f incisors, especially the upper ones, and the widths and anterior heights of the upper dental arch, possibly indicating a very low correlation or the lack o f correlation among the factors inducing crowding, i.e. increase in the size of incisors, and a narrower and longer upper dental arch.Provedeno je usporedno istraživanje dentometrijskih odlika sjekutiča u gornjoj i donjoj čeljusti s ciljem utvrđivanja uloge veličine navedenih zubi u procesu nastajanja primarne kompresije. Istraživanje je obuhvatilo 200 ispitanika (140 ženskih i 60 muških) s primarnom kompresijom i 100 eugnatih ispitanika (48 ženskih i 52 muška) koji su poslužili kao kontrolna skupina. Odabir je učinjen prema slijedećim mjerilima: zbijeni postav sjekutiča, završena mijena zubi, neutralni međučeljusni odnos (Kl I), odsutnost neke druge ortodontske anomalije. Dob je ograničena na 14 godina, kako bi se izbjegao mogući utjecaj tercijarne kompresije. Istraživanje je provedeno pomičnom kliznom mjerkom s točnošću od 0,5 mm na sadrenim odljevima gornjih i donjih čeljusti, a izmjereni su meziodistalni promjeri svih gornjih i donjih trajnih sjekutića. Nakon provedene statističke obrade i analize rezultata, može se zaključiti slijedeće: Aritmetičke sredine suma gornjih inciziva značajno su veće u dječaka, dok razlika između spolova za prosječne vrijednosti suma donjih inciziva nije značajna. Jedan od važnih čimbenika za nastajanje »crowdinga« je povećana zubna masa sjekutića, prvenstveno gornjih srednjih, a u djevojčica i donjih inciziva. Veličina inciziva nikako se ne može uzeti kao jedini razlog za nastanak kompresije, što potvrđuje i analiza širina i dužina gornjega zubnoga niza. U ispitanika s »crowdingom« zabilježene su značajno manje širine zubnih nizova u regiji premolara i molara te povećanje prednje gornje dužine. Analiza korelacija ukazuje tek na laganu povezanost ili nepovezanost veličine inciziva sa širinama i prednjom dužinom gornjega zubnog niza. To bi moglo ukazivati na vrlo malu povezanost, odnosno nepovezanost čimbenika koji dovode do »crowdinga«, a to su veći incizivi te uži i duži gornji zubni niz

Dentometrijske karakteristike ispitanika s primarnom kompresijom

A comparative study of dentometric characteristics of incisors in the upper and lower jaws was performed in on attempt to determine the role of the size of the mentioned teeth in the process of primary crowding. The study included 200 examinees (140 females and 60 males) with primary crowding and 100 eugnathic subjects (48 females and 52 males) as a control group. The sample was selected according to the following criteria: anterior crowding, completed exchange of teeth, neutral intermaxillary relationship (Angle class I), lack of other malocclusion. The age was limited to 14 years in order to avoid the possible influence of tertiary crowding. The study was carried out by means of a sliding-caliper with 1 mm precision on plaster casts of the upper and lower jaws, and the mesiodistal diameters of all the four permanent incisors in the upper and lower jaws were measured. After statistical analysis and interpretation of the results, the following was concluded: Arithmetical means of the sums of the upper incisors were considerably higher in boys, while the difference between the mean values of the sums of the lower incisors was insignificant. The subjects with crowding had significantly bigger upper but not lower incisors. One of the important factors for the occurrence of crowding were bigger incisors, especially the upper central ones, and in girls also the lower incisors. The size of the incisors should by no means be taken as the only cause o f crowding, as demonstrated by the analysis of the widths and heights o f the upper dental arch. Significantly smaller widths of dental arches in the premolar and molar regions, along with an increase in the anterior upper height were registered in the subjects with crowding. The analysis of correlations revealed only a slight association between the size o f incisors, especially the upper ones, and the widths and anterior heights of the upper dental arch, possibly indicating a very low correlation or the lack o f correlation among the factors inducing crowding, i.e. increase in the size of incisors, and a narrower and longer upper dental arch.Provedeno je usporedno istraživanje dentometrijskih odlika sjekutiča u gornjoj i donjoj čeljusti s ciljem utvrđivanja uloge veličine navedenih zubi u procesu nastajanja primarne kompresije. Istraživanje je obuhvatilo 200 ispitanika (140 ženskih i 60 muških) s primarnom kompresijom i 100 eugnatih ispitanika (48 ženskih i 52 muška) koji su poslužili kao kontrolna skupina. Odabir je učinjen prema slijedećim mjerilima: zbijeni postav sjekutiča, završena mijena zubi, neutralni međučeljusni odnos (Kl I), odsutnost neke druge ortodontske anomalije. Dob je ograničena na 14 godina, kako bi se izbjegao mogući utjecaj tercijarne kompresije. Istraživanje je provedeno pomičnom kliznom mjerkom s točnošću od 0,5 mm na sadrenim odljevima gornjih i donjih čeljusti, a izmjereni su meziodistalni promjeri svih gornjih i donjih trajnih sjekutića. Nakon provedene statističke obrade i analize rezultata, može se zaključiti slijedeće: Aritmetičke sredine suma gornjih inciziva značajno su veće u dječaka, dok razlika između spolova za prosječne vrijednosti suma donjih inciziva nije značajna. Jedan od važnih čimbenika za nastajanje »crowdinga« je povećana zubna masa sjekutića, prvenstveno gornjih srednjih, a u djevojčica i donjih inciziva. Veličina inciziva nikako se ne može uzeti kao jedini razlog za nastanak kompresije, što potvrđuje i analiza širina i dužina gornjega zubnoga niza. U ispitanika s »crowdingom« zabilježene su značajno manje širine zubnih nizova u regiji premolara i molara te povećanje prednje gornje dužine. Analiza korelacija ukazuje tek na laganu povezanost ili nepovezanost veličine inciziva sa širinama i prednjom dužinom gornjega zubnog niza. To bi moglo ukazivati na vrlo malu povezanost, odnosno nepovezanost čimbenika koji dovode do »crowdinga«, a to su veći incizivi te uži i duži gornji zubni niz

Construction of a Three-Dimensional Model of Teeth for Experimental Biomechanical Investigation by the Method of Finite Elements

Problemi s proučavanjem odgovora zuba na djelovanje sustava sila mnogo su složeniji i teze ih rješavamo od jednostavnog mjerenja same sile. Svrha je ovoga istraživanja razraditi vlastitu metodu trodimenzionalne digitalizacije zuba kako bi se što vjernije mogao izraditi njegov matematički model. Izraditi vlastiti trodimenzionalni matematički model zuba s pripadajućim potpornim strukturama u svrhu biomehanič- kih istraživanja metodom konačnih elemenata. Kao predložak za izradu matematičkog modela poslužio je gornji očnjak izvađen zbog paro- dontoloških razloga. Dobiven je trodimenzionalni matematički model gornjeg očnjaka koji se sastoji od 4000 elemenata oblika heksaedra i 2367 čvorova, što čini ukupno 7101 stupanj slobode cijelog modela. Periodontni ligament izmodeliran je cijelom duzinom korijena u širini od 0,25 mm. Sloj kompakte izmodeliran je u debljini od 2 mm. Zbog mogućnosti simulacije raznih položaja zubi, različite visine alveolarne kosti i terapijske situacije u kojima je izvršena ekstrakcija zubi, očekivati je da će se ova metoda u budućnosti još šire primjenjivati.Problems connected with the study of the response of the tooth to the effect of system forces are much more complex and difficult to solve than simple measurement of the forces themselves. The aim of this investigation was to develop a method for three-dimensional digitalization of teeth in order to produce a reliable mathematical model of a tooth. The construction of a three-dimensional mathematical model of a tooth with accompanying supporting structures for biomechanical investigations by the method of finite elements. An upper canine, extracted for parodontal reasons, served as the sample for construction of the mathematical model. A three- dimensional mathematical model of the upper canine was obtained, comprising 4000 elements of hexa- dic form and 2367 nodes, with a total of 7101 degrees of freedom for the whole model. The periodontal ligament was modelled for the whole length of the root, 0.25 mm in width. The layer of compact was modelled at a depth of 2 mm. It is anticipated that this method will be widely applied in the future, because of the possibility of simulating different positions of the tooth, and different heights of the alveolar bone and therapeutic situations in which teeth extractions are performed

Strain Distribution of Active Plates with Built-In Fan Screw According to Pagani

Provedena je eksperimentalna raščlamba veličine i distribucije sila nastalih djelovanjem aktivnih ploča u koje je bio simetrično i asimetrično ugrađen vijak po Paganiju. Željelo se utvrditi ovisnost veličine sile o sidrištu, odnosno o načinu ugradnje vijka i rezanja akrilatne baze. Rezultati mjerenja pokazali su razmjerno velike sile, koje su objema vrstama vijaka gotovo jednakih iznosa na objema stranama. Sile su u početku razmjerno velike, ali se zbog opadajučeg karaktera brzo smanjuju.An experimental analysis of the values and distribution of strains produced by the action o f active plates with symmetrically and asymmetrically built-in screw according to Pagani was performed, to determine the strain dependence on the anchorage, i.e. on the way o f screw building-in and acrylate base cut. Measurement results showed relatively high strains, which had almost identical values on both sides and with both types of screw. Initially, the strains were relatively high, but were rapidly reduced due to their decreasing character

Longitudinally Followed up Study of Maxillary Growth on Crossing from Mixed to Permanent Dentition

U longitudinalno praćenom uzorku sastavljenom od 28 ispitanika s normalnom i 45 ispitanika s dizgnatom okluzijom provedena je procjena čeljusnoga rasta u dvogodišnjem razdoblju pomoću analize četiriju kvalitativnih i osam kvantitativnih varijabla. Ispitanici su pregledani dva puta: tijekom nicanja prvih pretkutnjaka i dvije godine kasnije, tijekom nicanja drugih trajnih kutnjaka. Svrha istraživanja bila je utvrditi specifičnosti rasta svake od definiranih skupina, te upozoriti na značajnije razlike među njima. Rezultati istraživanja uputili su na sljedeće: u dizgnatoj skupini najučestalija je klasa II, a promjena između dva pregleda nema. Transverzalni pomaci mandibule učestaliji su i jače izraženi u dizgnatoj skupini, s povećanjem učestalosti tijekom dvogodišnjega razdoblja. Zbijenost ili rastresitost pojavljuju se u obje skupine i podložne su dinamici. Zbijenost je učestalija u dizgnatoj skupini i brojčano raste s dobi, dok je rastresitost nešto veća u normalnoj skupini i izrazito se smanjuje s dobi. U cjelokupnu uzorku, širina i visina gornje čeljusti lagano se povećavaju, dok se stražnja dužina smanjuje, kao i incizalna stepenica. U skupini s normalnom okluzijom raste i dubina prijeklopa, a u dizgnatoj prednja dužina. U skupini s normalnom okluzijom statistički su značajno veće vrijednosti varijabla: širine u oba pregleda, a u drugom pregledu prednja dužina i visina. U dizgnatoj skupini u oba pregleda nešto su veće vrijednosti zbroja inciziva, incizalne stepenice, dubine zagriza, a pri prvom pregledu i stražnje dužine.Maxillary growth was assessed in a sample of 28 subjects with normal and 45 subjects with dysgnathic occlusion, longitudinally followed up during a two-year period. Four qualitative and 8 quantitative variables were observed. The subjects were examined on two occasions: during eruption of first premolars and two years later, during eruption of second permanent molars. The aim of the study was to determine the specificity of the growth in each of the groups and to point to major differences between them. Results of the study suggested the following conclusions: class II was most frequent in the dysgnathic group, with no changes between the two examinations; transversal shift of the mandible was more frequent and pronounced in the dysgnathic group, with an increasing frequency during the two-year period of observation; compactness and looseness undergoing dynamic changes were observed in both groups; compactness was more frequent in the dysgnathic group and increased in number with age, whereas looseness was slightly higher in the normal group and markedly decreased with age. Considering the sample as a whole, the width and height of the maxilla were on a slight increase. In the group of subjects with normal occlusion the same was also observed for the depth of overbite, and in the group of dysgnathic subjects for the anterior length. In the group with normal occlusion, the values of the following variables were statistically increased: widths on both examinations, and anterior length and height on the second examination. In the group of dysgnathic subjects, the values of the sum of incisors, incisal step and bite depth were higher on both examinations, and so were also posterior lengths on the initial examination