Anatomical features of the palatal root canal in maxillary first molars and their influence on endodontic procedure

Introduction: More detailed acquaintance with specialist endodontic literature and treating complicated endodontic cases have revealed that the palatal root canal in maxillary first molars has different features from generally accepted simplicity. Aim: The aim of this study was to investigate the number, orientation and shape of the curvature of the palatal root canal in maxillary first molars, characteristics that may have great influence on the procedure and outcome of endodontic therapy. Materials and methods: Material consisted of 100 left and 100 right extracted human first maxillary molars. Extended access cavity was prepared, and canal orifices were detected using an endodontic probe. K-flex file no 15 or 20 was then introduced into the palatal root canal until the tip appeared at the apical foramen. The tooth was radiographed from buccal-oral (clinical) and mesial-distal (proximal) aspect under standardized conditions. On magnified images, the number and character of canal, orientation and shape of the curvature were determined. Results: One palatal root canal was found in each of 200 teeth. From the clinical projection, 60% of the palatal canals appeared curved and from the proximal 93.5% (p<0.05). Out of 120 curved canals from the clinical aspect, 66.7% were oriented distally and 33.3% mesially. From the proximal projection, of 187 curved canals 68,4% were oriented buccally, and 31,6% palatally. From the clinical projection, 49.2% were C-shaped, and 32.5 % with the J-shaped curvature. Only 18.3% of the palatal canals were with the S-shaped curvature (p<0.05). Conclusions: Upon presented results, practitioners may predict with high significance the character, orientation and curvature shape of the palatal root canal in maxillary first molars in the buccal-oral dimension which is not visible on clinical radiographs and, therefore, perform more successful endodontic treatment

Morfološke odlike meziobukalnih kanala prvih maksilarnih molara

Introduction. The first maxillary molar is a tooth with three roots, and mesiobuccal one is with the most complex canal morphology. Factors influencing variations of its morphology are numerous, and may significantly complicate endodontic treatment. Objective. The objective was to investigate the number, configuration and curvature orientation of the mesiobuccal root canals in the maxillary first molars. Methods. The study was conducted on 200 mesiobuccal (MB) roots of extracted first molars in human subjects using radiography. In each canal Flexofile was introduced until reaching the apical foramen and the root was then radiographed in series from two projections. Number of root canals (MB1, MB2 and MB3), configuration according to Vertucci classification, and the orientation of the curvature were established. Relevant statistical parameters and the significance of differences were computed (p lt 0.05). Results. Of total 200 mesiobuccal roots 86.5% were with two, 9% with three, and 4.5% with a single canal. Most frequent configurations were type IV (36%) and II (34.5%). From the clinical projection all MB1 canals were oriented distally, from the proximal 78% palatally and 22% buccally. The orientation of all MB2 canals was distal from the clinical projection, from the proximal projection 76% were oriented palatally, and 24% buccally. The MB3 canal was always oriented distally from the clinical projection, and buccally from the proximal aspect. Conclusion. The mesiobuccal roots of the first maxillary molars showed multiple canals in 96%, with dominant Vertucci type II and IV of configuration. All canals were curved.Uvod. Prvi maksilarni molar je zub koji najčešće ima tri korena, a meziobukalni je s najsloženijom kanalnom morfologijom. Faktora koji utiču na varijabilnost njegove morfologije ima mnogo i značajno otežavaju endodontsko lečenje ovih zuba. Cilj rada. Cilj rada je bio da se na ekstrahovanim prvim maksilarnim molarima ispitaju broj, konfiguracija i smer povijenosti meziobukalnih kanala. Metode rada. Istraživanja su urađena na 200 meziobukalnih (MB) korenova ekstrahovanih humanih prvih maksilarnih molara metodom radiografisanja. U svaki pojedinačni kanal postavljen je instrument tipa Flexofile do pojave na anatomskom otvoru i zatim radiografisan serijom snimaka iz dve projekcije. Zabeleženi su broj kanala (MB1, MB2 i MB3), konfiguracija prema Vertučijevoj (Vertucci) klasifikaciji i smer povijenosti. Utvrđeni su relevantni statistički parametri i razlike na nivou značajnosti p lt 0,05. Rezultati. Od ukupno 200 MB korenova, sa dva kanala bilo je njih 86,5% , sa tri 9%, a s jednim kanalom 4,5%. Najčešći tipovi kanalne konfiguracije bili su IV (36%) i II (34,5%). Smer povijenosti svih MB1 kanala iz kliničke projekcije bio je distalan, a iz aproksimalne 78% palatinalan i 22% bukalan. Svi MB2 kanali iz kliničke projekcije bili su distalno povijeni, a iz aproksimalne 76% palatinalno i 24% bukalno. MB3 kanal je bio povijen uvek distalno u kliničkoj, a najčešće bukalno u aproksimalnoj projekciji snimanja. Zaključak. Meziobukalni korenovi prvih maksilarnih molara su u 96% slučajeva imali višestruki broj kanala i konfiguracijski su pripadali tipu IV i II Vertučijeve klasifikacije. Svi kanali su bili povijeni

Endodontsko lečenje zuba s različitim oblicima krivina korenskih kanala - dva prikaza iz prakse

Endodontic treatment of the teeth with severe root canal curvatures has become one of the greatest problems in clinical practice. Recently, new instruments and techniques have been introduced in the endodontic procedure. The aim of this study was, on the basis of clinical practice, to show the possibilities of the endodontic treatment in the teeth with severely curved root canals, after dependable decision about endodontic instruments and techniques. This article presents a complete endodontic procedure in two teeth with different curvature shape of the root canal in patients that were treated at the Department of Restorative Dentistry and Endodontics, School of Dentistry, Belgrade. Coronal to apical 'crown down' technique was used for the root canal preparation with hand NiTi ProTaper instruments with progressive multicone design. The main reasons for choosing manual technique were complexity, shape of presented curvatures and better tactile sensation control of canal instruments in order to avoid possible mistakes and complications. Clinical X-rays of the teeth with permanent obturation clearly showed that extremes of the root canal morphology could be successfully solved by the right choice of all factors during endodontic procedure.Endodontsko lečenje zuba s jako zakrivljenim korenovima je značajan problem u praksi. Primena novih instrumenata i tehnika u lečenju ovakvih zuba poslednjih godina je postala sve izvesnija.Cilj ovog rada je bio da se na primerima iz kliničke prakse ukaže na mogućnost endodontskog lečenjazuba s veoma izraženim krivinama kanala korena nakon pravilnog izbora endodontskih instrumenata, odnosno tehnike instrumentacije. U ovom radu je prikazan celokupni endodontski postupak lečenja dva zuba pacijenata Klinike za bolesti zuba Stomatološkog fakulteta u Beogradu sa različitim oblicima krivine centralnog korenskog kanala. Prime-njena je krunično-apeksna 'crown-down' tehnika preparacije uz korišćenje ručnih nikl-titanijumskih instrumenata tipa ProTaper s progresivnom multikoničnošću. Osnovni razlozi za odabir ručne tehnike preparacije bili su složenost morfologije, oblik prikazanih krivina i bolja taktilno-senzorna kontrola kanalnih instrumenata; cilj je bio da se izbegnu moguće greške i komplikacije. Prikazani radiografski snimci zuba sa jasno opturiranim kanalnim sistemom pokazuju da su i ekstremi morfološkog izgleda kanala rešivi pravilnim odabirom svih činilaca endodontske procedure.

Uticaj kompozita s malom kontrakcijom i konvencionalnih kompozita na postoperacionu osetljivost zuba

Introduction. Postoperative sensitivity in restorative dentistry can be related to preparation trauma, dentin adhesives' ability to seal open dentinal tubules, deformation of restorations under occlusal stresses and microleakage. Objective. The study assessed possible reduction in postoperative sensitivity with low shrinkage compared to conventional composites using different bonding agents and the influence of the operator skill on the incidence of postoperative sensitivity. Methods. Nine hundred and sixty permanent premolars and molars with primary carious lesions from patients 21 to 40 years old were used. Cavities 2 to 3 mm deep and with margins in enamel were prepared by four operators. Two operators had five years (A and B) and two had over 20 years (C and D) of clinical experience. Teeth were divided into eight groups each contained 120 restorations: (1) Els®+James-2 (original formula), (2) Els®+James-2 (new formula), (3) Els®+Excite, (4) InTenSe®+James-2 (original formula), (5) InTenSe®+James-2 (new formula), (6) InTenSe®+Excite, (7) Tetric Ceram®+Excite, and (8) Point 4®+OptiBond Solo Plus. At 14 days postoperatively, two independent operators, who did not take part in the clinical procedure, assessed postoperative teeth sensitivity using special questionnaires. Data were analyzed using non-parametric chi-square, Mann-Whitney and ANOVA tests. Results. Group 8 showed significantly higher score than the other groups. Less postoperative sensitivity was reported with two low-shrinkage composites (groups 2, 3, and 5) but with no significant difference. There was no statistical difference between groups 1, 2, 3, 4, 5, 6 and 7. Operator A had the highest postoperative sensitivity score compared to the other three. Conclusion. Conventional composite material Point 4® with its bonding agent caused significantly more postoperative sensitivity than low shrinkage composites combined with different adhesives. Operator skill influenced the incidence of postoperative sensitivity.Uvod. Posle postavljanja kompozitnih ispuna može da se javi postoperaciona osetljivost izazvana preparacionom traumom, sposobnošću adhezivnog sistema da hermetički zatvori dentinske kanaliće, deformacijom pod okluzalnim opterećenjem ili prodorom bakterijskih toksina. Cilj rada. Cilj istraživanja je bio da se ispita da li je osetljivost zuba manja kod kompozita s malom kontrakcijom u poređenju s konvencionalnim kompozitima i odgovarajućim adhezivnim sistemima, kao i uticaj veštine stomatologa na incidenciju postoperacione osetljivosti zuba. Metode rada. Na 960 premolara i molara stalne denticije s primarnim karijesom, pacijenata starosti od 21 godine do 40 godina, preparisani su kaviteti dubine 2-3 mm s rubovima u gleđi. Čitavu proceduru su obavila četiri specijalista stomatologije, od kojih su dva imala pet (A i B), a druga dva više od 20 godina kliničkog iskustva (C i D). Zubi su svrstani u osam grupa od po 120 uzoraka prema korišćenom kompozitnom i adhezivnom sistemu: 1) Els®+James-2; 2) Els®+James-2 (nova formula); 3) Els®+Excite; 4) InTenSe®+James-2; 5) InTenSe®+James-2 (nova formula); 6) InTenSe®+Excite; 7) Tetric Ceram®+Excite; i 8) Point 4®+OptiBond Solo Plus. Dve nedelje posle intervencije dva nezavisna stomatologa (koja nisu učestvovala u kliničkoj proceduri) ocenjivala su posebnim upitnicima postoperacionu osetljivost zuba. Podaci su analizirani neparametrijskim c2, Man-Vitnijevim (Mann-Whitney) i ANOVA testom. Rezultati. U osmoj grupi utvrđena je statistički značajno češća postoperaciona osetljivost nego u ostalim grupama zuba. Nije bilo statistički značajne razlike između grupa 1, 2, 3, 4, 5, 6 i 7. Kompoziti sa nižom polimerizacionom kontrakcijom izazvali su manju postoperacionu ostetljivost, ali bez statističke značajnosti razlika (grupe 2, 3 i 5). Kod stomatologa A javljala se statistički značajno češće postoperaciona osetljivost nego kod ostala tri. Zaključak. Tip kompozitnog materijala s odgovarajućim adhezivnim sistemom i spretnost stomatologa utiču na učestalost pojave osetljivosti zuba posle restauracija srednje dubokih kaviteta II klase

Herpesviruses in Periapical Pathoses: An Updated Systematic Review

Apical periodontitis represents a chronic inflammation and destruction of periradicular tissue caused by polymicrobial infection of endodontic origin. The aim of this systematic review was to make an update on findings related to Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) presence in periapical pathoses and to correlate these findings with clinical, histopathological and radiographic features of periapical lesions. Methods were based on the preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement. A search was performed using PubMed, Web of Science and SCOPUS. Search key words included the following medical subjects heading terms: (periapical disease OR apical periodontitis OR periapical lesions OR periapical abscess) AND (viruses OR herpesvir*). A manual search involved references from articles retrieved for possible inclusion. The search, evaluation, and critical appraisal of articles were performed by two independent judges. Collected data were analyzed using the measures of descriptive statistics. The final review has included twenty nine articles related to herpesviral presence periapical pathoses. Qualitative analysis indicated that EBV HCMV, and HHV-8 were the most prevalent species in periapical pathoses. Our findings suggest that there is wide variety of herpesviruses detection rates in periapical pathoses in relation to their clinical, histopathological and radiographic features

Prevalence of Apical Periodontitis and Conventional Nonsurgical Root Canal Treatment in General Adult Population: An Updated Systematic Review and Meta-analysis of Cross-sectional Studies Published between 2012 and 2020

Introduction This study aimed to summarize data on apical periodontitis (AP) and nonsurgical root canal treatment (NSRCT) prevalence and risk factors related to age, gender, and quality of restorative and endodontic treatment in the general population from cross-sectional studies published between 2012 and 2020. Methods An electronic search was performed in the following databases: Web of Science, Scopus, and PubMed. The conducted literature search covered studies published between 2012 and 2020, without restrictions on language. The STROBE and NOS tools were used for quality assessment of the included studies. Results Sixteen articles were included in the review. In total, 200,041 teeth were examined. On average, 6.3% of teeth had AP, and 7.4% had NSRCT. Forty-one percent of RCT teeth had AP, and 3.5% of untreated teeth had AP. Female patients were less prone to AP in endodontically treated teeth only, compared with male patients (P < .001). Variable stratification of age subgroups among included studies prevented us from conducting a meta-analysis. An increase in AP frequency was found in teeth with inadequate restorative and endodontic treatment (P < .001 and P < .001, respectively). Because of high heterogeneity, these results should be taken with caution. Conclusions There is an increased AP prevalence in the adult general population compared with data from 2012 (6.3% versus 5.4%) in both endodontically treated (41.3% versus 35.9%) and untreated teeth (3.5% versus 2.1%). In addition, AP developed less frequently in female patients with endodontically treated teeth and in teeth with inadequate compared with adequate restorative and endodontic treatment.This is the peer-reviewed version of the article: Jakovljevic A, Nikolic N, Jacimovic J, Pavlovic O, Milicic B, Beljic-Ivanovic K, Miletic M, Andric M, Milasin J. Prevalence of Apical Periodontitis and Conventional Nonsurgical Root Canal Treatment in General Adult Population: An Updated Systematic Review and Meta-analysis of Cross-sectional Studies Published between 2012–2020. Journal of Endodontics. 2020;46(10):1371-1386.e8. [https://doi.org/10.1016/j.joen.2020.07.007

Uticaj različitih tehnika mašinske preparacije na originalnu anatomiju kanala korenova prvih maksilarnih molara

The idea for this study emerged from everyday problems that practitioners are faced in their clinical work during endodontic therapy of teeth with complex root canal anatomy, and due to a lack of information and sufficient data from the literature about influence of machine driven instrumentation techniques on the original anatomy of the root canal system of first maxillary molars. Crucial aim of this dissertation followed the idea of the study, and upon that fact the major tasks were given in order to choose relevant group of maxillary first molars: A) teeth with three distinctive roots and with canal configuration of Vertucci type IV in the mesiobuccal root, and B) teeth with fused roots. Detailed evaluation of several parameters that will define changes of anatomical details were conducted before and after root canal preparation with five machine driven instrumentation techniques: ProTaper Next, Revo-S, WaveOne, Tilos and Self Adjusting File (SAF). With the aid of Cone Beam Computed Tomography (CBCT), introduced in endodontics in the last decade, at the distance of 1.0 mm and 0.1 mm along each root canal the following measurements were conducted: canal walls thickness, dimensions of root canal diameters measured from two directions, and surface area of the root canal cross sections before and after mechanical preparation. The influence, mode of effects and differences of those effects between applied machine driven techniques on the original anatomy of root canals in first maxillary molars were analyzed using appropriate statistical methods. Results of the studies of the anatomical features of two groups of maxillary first molars showed that all dimensions of the tooth crown measured at the level of the pulp chamber floor were significantly greater in teeth with three distinctive roots than in those with fused roots. It was also shown that distances between centers of the canal orifices were significantly different between the two groups of maxillary first molars. These results are of great clinical importance, and with no similar findings in available endodontic literature. Changes in the root canal diameters after mechanical preparation were least in the apical third, and significantly greater at the orifice and in the coronal third of all root canals irrespective to the instrumentation technique. Degree of changes in dimensions of canal diameter was different between the group with three distinctive roots and group with fused roots...Ideja za istraživanje proizašla je iz problematike sa kojom se susreću terapeuti u kliničkom radu tokom endodontske preparacije zuba sa komplikovanim kanalnim sistemima i nedostataka literaturinih podataka o uticaju mašinskih tehnika instrumentacije na originalnu anatomiju kanalnog sistema prvih maksilarnih molara. Osnovni cilj ove disertacije je pratio ideju istraživanja, na osnovu čega su postavljeni i konkretni zadaci, koji su rukovodili odabir relevantnih grupa prvih maksilarnih molara: I – zubi sa tri odvojena korena i morfološkim tipom Vertucci IV kanala u mezio-bukalnom korenu i II – zubi sa fuzionisanim korenovima. Na njima su sprovedena proučavanja parametara koji će definisati promene anatomskih detalja pre i posle instrumentacije kanala korena koristeći pet specifičnih sistema mašinske obrade: ProTaper Next, Revo-S, WaveOne, Tilos i Self Adjusting File (SAF). Koristeći kompjuterizovanu tomografiju konusnog zraka (CBCT), uvedenu u endodonciju pre nepune decenije, na rastojanju od 1,0 i 0,1 mm duž svakog kanala merene su: debljine zidova korenskih kanala, dimenzije prečnika kanala iz dva osnovna pravca i površine poprečnih preseka kanala pre i posle mašinske preparacije. Statističkim metodima analizirano je da li i na koji način primenjeni sistemi za mašinsku preparaciju utiču na originalnu anatomiju prvih maksilarnih molara i da li između njih postoje razlike. Rezultati antomskih karaktersitika dve grupe prvih maksilarnih molara pokazali su da su sve dimenzije krunice zuba na nivou dna krunične komore veće u grupi sa tri odvojena nego u grupi sa fuzionisanim korenovima. Takođe je pokazano da su rastojanja između cenatara ulaza u korenske kanale statistički zančajno različite između ove dve grupe prvih maksilarnih molara, što je od izuzetnog kliničkog značaja, a bez sličnih nalaza u dostupnoj literaturi. Promene dimenzije prečnika kanala posle preparacije su bile najmanje u njihovoj apeksnoj trećini, a statistički značajno veće na ulazu i u koronarnoj trećini kanala. Stepen promena dimenzija prečnika razlikovao se između grupe sa tri odvojena i grupe sa fuzionisanim korenovima. U obe grupe zuba su najizrazitije promene vrednosti prečnika kanala bile na njihovom ulazu, a najmanje u apeksnoj trećini, i to posle primene svih pet tehnika instrumentacije..

Effect of different machine driven instrumentation techniques on the original root canal anatomy of the first maxillary molars

Ideja za istraživanje proizašla je iz problematike sa kojom se susreću terapeuti u kliničkom radu tokom endodontske preparacije zuba sa komplikovanim kanalnim sistemima i nedostataka literaturinih podataka o uticaju mašinskih tehnika instrumentacije na originalnu anatomiju kanalnog sistema prvih maksilarnih molara. Osnovni cilj ove disertacije je pratio ideju istraživanja, na osnovu čega su postavljeni i konkretni zadaci, koji su rukovodili odabir relevantnih grupa prvih maksilarnih molara: I – zubi sa tri odvojena korena i morfološkim tipom Vertucci IV kanala u mezio-bukalnom korenu i II – zubi sa fuzionisanim korenovima. Na njima su sprovedena proučavanja parametara koji će definisati promene anatomskih detalja pre i posle instrumentacije kanala korena koristeći pet specifičnih sistema mašinske obrade: ProTaper Next, Revo-S, WaveOne, Tilos i Self Adjusting File (SAF). Koristeći kompjuterizovanu tomografiju konusnog zraka (CBCT), uvedenu u endodonciju pre nepune decenije, na rastojanju od 1,0 i 0,1 mm duž svakog kanala merene su: debljine zidova korenskih kanala, dimenzije prečnika kanala iz dva osnovna pravca i površine poprečnih preseka kanala pre i posle mašinske preparacije. Statističkim metodima analizirano je da li i na koji način primenjeni sistemi za mašinsku preparaciju utiču na originalnu anatomiju prvih maksilarnih molara i da li između njih postoje razlike. Rezultati antomskih karaktersitika dve grupe prvih maksilarnih molara pokazali su da su sve dimenzije krunice zuba na nivou dna krunične komore veće u grupi sa tri odvojena nego u grupi sa fuzionisanim korenovima. Takođe je pokazano da su rastojanja između cenatara ulaza u korenske kanale statistički zančajno različite između ove dve grupe prvih maksilarnih molara, što je od izuzetnog kliničkog značaja, a bez sličnih nalaza u dostupnoj literaturi. Promene dimenzije prečnika kanala posle preparacije su bile najmanje u njihovoj apeksnoj trećini, a statistički značajno veće na ulazu i u koronarnoj trećini kanala. Stepen promena dimenzija prečnika razlikovao se između grupe sa tri odvojena i grupe sa fuzionisanim korenovima. U obe grupe zuba su najizrazitije promene vrednosti prečnika kanala bile na njihovom ulazu, a najmanje u apeksnoj trećini, i to posle primene svih pet tehnika instrumentacije...The idea for this study emerged from everyday problems that practitioners are faced in their clinical work during endodontic therapy of teeth with complex root canal anatomy, and due to a lack of information and sufficient data from the literature about influence of machine driven instrumentation techniques on the original anatomy of the root canal system of first maxillary molars. Crucial aim of this dissertation followed the idea of the study, and upon that fact the major tasks were given in order to choose relevant group of maxillary first molars: A) teeth with three distinctive roots and with canal configuration of Vertucci type IV in the mesiobuccal root, and B) teeth with fused roots. Detailed evaluation of several parameters that will define changes of anatomical details were conducted before and after root canal preparation with five machine driven instrumentation techniques: ProTaper Next, Revo-S, WaveOne, Tilos and Self Adjusting File (SAF). With the aid of Cone Beam Computed Tomography (CBCT), introduced in endodontics in the last decade, at the distance of 1.0 mm and 0.1 mm along each root canal the following measurements were conducted: canal walls thickness, dimensions of root canal diameters measured from two directions, and surface area of the root canal cross sections before and after mechanical preparation. The influence, mode of effects and differences of those effects between applied machine driven techniques on the original anatomy of root canals in first maxillary molars were analyzed using appropriate statistical methods. Results of the studies of the anatomical features of two groups of maxillary first molars showed that all dimensions of the tooth crown measured at the level of the pulp chamber floor were significantly greater in teeth with three distinctive roots than in those with fused roots. It was also shown that distances between centers of the canal orifices were significantly different between the two groups of maxillary first molars. These results are of great clinical importance, and with no similar findings in available endodontic literature. Changes in the root canal diameters after mechanical preparation were least in the apical third, and significantly greater at the orifice and in the coronal third of all root canals irrespective to the instrumentation technique. Degree of changes in dimensions of canal diameter was different between the group with three distinctive roots and group with fused roots..

Effect of different machine driven instrumentation techniques on the original root canal anatomy of the first maxillary molars

Ideja za istraživanje proizašla je iz problematike sa kojom se susreću terapeuti u kliničkom radu tokom endodontske preparacije zuba sa komplikovanim kanalnim sistemima i nedostataka literaturinih podataka o uticaju mašinskih tehnika instrumentacije na originalnu anatomiju kanalnog sistema prvih maksilarnih molara. Osnovni cilj ove disertacije je pratio ideju istraživanja, na osnovu čega su postavljeni i konkretni zadaci, koji su rukovodili odabir relevantnih grupa prvih maksilarnih molara: I – zubi sa tri odvojena korena i morfološkim tipom Vertucci IV kanala u mezio-bukalnom korenu i II – zubi sa fuzionisanim korenovima. Na njima su sprovedena proučavanja parametara koji će definisati promene anatomskih detalja pre i posle instrumentacije kanala korena koristeći pet specifičnih sistema mašinske obrade: ProTaper Next, Revo-S, WaveOne, Tilos i Self Adjusting File (SAF). Koristeći kompjuterizovanu tomografiju konusnog zraka (CBCT), uvedenu u endodonciju pre nepune decenije, na rastojanju od 1,0 i 0,1 mm duž svakog kanala merene su: debljine zidova korenskih kanala, dimenzije prečnika kanala iz dva osnovna pravca i površine poprečnih preseka kanala pre i posle mašinske preparacije. Statističkim metodima analizirano je da li i na koji način primenjeni sistemi za mašinsku preparaciju utiču na originalnu anatomiju prvih maksilarnih molara i da li između njih postoje razlike. Rezultati antomskih karaktersitika dve grupe prvih maksilarnih molara pokazali su da su sve dimenzije krunice zuba na nivou dna krunične komore veće u grupi sa tri odvojena nego u grupi sa fuzionisanim korenovima. Takođe je pokazano da su rastojanja između cenatara ulaza u korenske kanale statistički zančajno različite između ove dve grupe prvih maksilarnih molara, što je od izuzetnog kliničkog značaja, a bez sličnih nalaza u dostupnoj literaturi. Promene dimenzije prečnika kanala posle preparacije su bile najmanje u njihovoj apeksnoj trećini, a statistički značajno veće na ulazu i u koronarnoj trećini kanala. Stepen promena dimenzija prečnika razlikovao se između grupe sa tri odvojena i grupe sa fuzionisanim korenovima. U obe grupe zuba su najizrazitije promene vrednosti prečnika kanala bile na njihovom ulazu, a najmanje u apeksnoj trećini, i to posle primene svih pet tehnika instrumentacije...The idea for this study emerged from everyday problems that practitioners are faced in their clinical work during endodontic therapy of teeth with complex root canal anatomy, and due to a lack of information and sufficient data from the literature about influence of machine driven instrumentation techniques on the original anatomy of the root canal system of first maxillary molars. Crucial aim of this dissertation followed the idea of the study, and upon that fact the major tasks were given in order to choose relevant group of maxillary first molars: A) teeth with three distinctive roots and with canal configuration of Vertucci type IV in the mesiobuccal root, and B) teeth with fused roots. Detailed evaluation of several parameters that will define changes of anatomical details were conducted before and after root canal preparation with five machine driven instrumentation techniques: ProTaper Next, Revo-S, WaveOne, Tilos and Self Adjusting File (SAF). With the aid of Cone Beam Computed Tomography (CBCT), introduced in endodontics in the last decade, at the distance of 1.0 mm and 0.1 mm along each root canal the following measurements were conducted: canal walls thickness, dimensions of root canal diameters measured from two directions, and surface area of the root canal cross sections before and after mechanical preparation. The influence, mode of effects and differences of those effects between applied machine driven techniques on the original anatomy of root canals in first maxillary molars were analyzed using appropriate statistical methods. Results of the studies of the anatomical features of two groups of maxillary first molars showed that all dimensions of the tooth crown measured at the level of the pulp chamber floor were significantly greater in teeth with three distinctive roots than in those with fused roots. It was also shown that distances between centers of the canal orifices were significantly different between the two groups of maxillary first molars. These results are of great clinical importance, and with no similar findings in available endodontic literature. Changes in the root canal diameters after mechanical preparation were least in the apical third, and significantly greater at the orifice and in the coronal third of all root canals irrespective to the instrumentation technique. Degree of changes in dimensions of canal diameter was different between the group with three distinctive roots and group with fused roots..