Dimensions of Occlusoproximal Cavitated Carious Lesions as a Cut-Off Point for Restorative Decision in Primary Teeth

ABSTRACT Objective: To investigate whether the dimensions of cavitated dentin carious lesions on the occlusoproximal surfaces of primary teeth could predict the location of cement-enamel junction (CEJ). Material and Methods: Two hundred extracted primary molars were selected and digital images were obtained. The teeth were set in arch models for clinical measurement. The cervical-occlusal (CO) and buccal-lingual/palatal (BL/P) cavities' dimensions were obtained by digital (Image J) and clinical (periodontal millimeter probe) assessments. The cervical margin location was also determined. The thresholds (cut-off points) were determined by sensitivity, specificity and the areas under the receiver operating characteristics curves (Az) for the two methods. Pearson's correlation coefficient was used to investigate the correlation between clinical and digital measurements. Logistic regression analysis was performed to evaluate the association between the dimensions and cervical margin location. Results: There was a strong correlation between methods for all measurements (CO: r=0.90, VL/P: r=0.95). Cavities with BL/P distance higher than 4.5 mm and CO dimension higher than 3.5 mm had a lower chance of presenting the cervical limit above the CEJ, irrespective of the measurement method. Conclusion: CO and VL/P dimensions could be used to predict the CEJ location and, ultimately, as a clinical parameter for restorative decision-making.

Accuracy of cone-beam CT in detecting vertical root fractures in teeth with post-endodontic restorations: an in vitro study

The aim of this study was to evaluate the accuracy of cone-beam CT (CBCT) for the detection of artificially created vertical root fractures (VRF) in extracted teeth restored with metallic (MP) and fiberglass (FGP) posts. After root canal obturation, 60 extracted human premolars were scanned by using the highest-resolution settings of a CBCT unit. Theprepared roots were randomly divided into three groups: group C (control group): non-restored and non-endodontically treated teeth (n = 20); group MP (n = 20); group FGP (n = 20). In all groups, 10 teeth were artificially fractured. Two external and independent observers blindly recorded the presence or absence of VRF. Sensitivity, specificity, accuracy, intra-and interobserver agreement were calculated. Kappa value for inter-and intraobserver agreement was 0.82 and 0.84 respectively, demonstrating goodagreement. The highest values for sensitivity (0.80 -0.90), specificity (1.00) and accuracy (0.90 -0.95) were found in the control group. The teeth with FGP restoration presented the lowest sensitivity (0.30 -0.50) and accuracy (0.60 -0.65) values. Both examiners had a good performance in the diagnosis of fractures in teeth with MP, with accuracy ranging between 0.85 -0.90. The presence of MP did not influence accuracy; however, the presence of FGP reduced the diagnostic capacity of CBCT.

The potential effect of instrumentation with different nickel titanium rotary systems on dentinal crack formation-An in vitro study.

The potential mechanical impact of different rotary systems used for root canal preparation has been a matter of debate for long. The aim of this study was to explore the incidence of dentinal cracks after root canal instrumentation with various rotary systems, in vitro. One hundred and eighty intact lower central incisors were selected and randomly divided into fourteen treatment groups (n = 12/group) and a control group (n = 12). After decoronation, the root canals were instrumented with fourteen different rotary systems (E3, E3 azure, NT2, Hyflex CM, Hyflex EDM, 2Shape, OneCurve, ProTaper Next, ProTaper Gold, WaveOne Gold, Mtwo, Reciproc Blue, TF adaptive, K3XF). All roots were horizontally sectioned at 3, 6, and 9 mm from the apex with a low-speed saw under water-cooling. The slices were then examined under stereomicroscope for dentinal cracks. No cracks were found in the control group. Cracks were found in all treatment groups, predominantly in the 3 mm slices. There was no statistically significant difference in the number of cracks when comparing the different systems to each other at any section level. At 3 mm, however, five of the studied systems, namely K3XF (p = 0.004), Protaper Next (p = 0.001), Reciproc Blue (p<0.001), TF adaptive (p = 0.050), and 2Shape (p = 0.009) presented a significantly higher number of cracks than the control group. Within the limitations of this study, instrumented canals presented dentinal cracks, while uninstrumented ones presented no cracks after sectioning. There seems to be no significant difference among the tested systems regarding crack formation in the instrumented root canal wall. Crack formation occurred irrespective of the motion of the rotary system (rotational or reciprocation). Further studies are needed to clarify the factors that contribute to crack formation in the case of each individual rotary system.

Regional contribution of proteoglycans to the fracture toughness of the dentin extracellular matrix.

This study investigated the contribution of small leucine rich proteoglycans (SLRPs) to the fracture toughness of the dentin extracellular matrix (ECM) by enzymatically-assisted selective removal of glycosaminoglycan chains (GAGs) and proteoglycans (PGs) core protein. We adapted the Mode III trouser tear test to evaluate the energy required to tear the dentin ECM. Trouser-shaped dentin specimens from crown and root were demineralized. Depletion of GAGs and PGs followed enzymatic digestion using chondroitinase ABC (c-ABC) and matrix metalloproteinase 3 (MMP-3), respectively. The legs from specimen were stretched under tensile force and the load at tear propagation was determined to calculate the tear energy (T, kJ/m2). SLRPs decorin and biglycan were visualized by immunohistochemistry and ECM tear pattern was analyzed in SEM. Results showed T of crown ECM was not affected by PGs/GAGs depletion (p = 0.799), whereas the removal of PGs significantly reduced T in root dentin ECM (p = 0.001). Root dentin ECM exhibited higher T than crown (p < 0.03), however no regional difference are present after PG depletion (p = 0.480). Immunohistochemistry confirmed removal of GAGs and PGs. SEM images showed structural modifications after PGs/GAGs removal such as enlargement of dentinal tubules, increased interfibrillar spaces and presence of untwisted fibrils with increased diameter. Findings indicate that the capacity of the PGs to unfold and untwist contribute to the dentin ECM resistance to tear, possibly influencing crack growth propagation. The regional differences are likely an evolutionary design to increase tooth survival, that undergoes repetitive mechanical loading and load stress dissipation over a lifetime of an individual.

Odontología deportiva y prevención de trauma dentoalveolar / Sports dentistry and prevention of dentoalveolar traumas

La odontología deportiva es la rama de la medicina deportiva que se ocupa de la prevención y el tratamiento de las lesiones bucodentales y las enfermedades orales asociadas al deporte y el ejercicio. Por lo que se hace necesario la intervención de profesionales de la salud bucodental para hacer evaluaciones del deportista y el deporte que practica para ver los riesgos que puede tener de desarrollar y sufrir lesiones bucodentales como traumas dentoalveolares y lesiones no cariosas. Y de este modo realizar las recomendaciones a cada paciente que practica deporte, de los elementos que deben usar como equipamiento bucodental para evitar o reducir el daño dentoalveolar (AU)

Sports dentistry is the branch of sports medicine that deals with the prevention and treatment of oral injuries and oral diseases associated with sports and exercise. Therefore it is necessary the intervention of oral health professionals to make evaluations of the athlete and the sport he practices to see the risks that may have to develop and suffer oral injuries such as dentoalveolar trauma and non-carious lesions. And in this way make the recommendations to each patient who practices sports, of the elements that should be used as oral equipment to avoid or reduce dentoalveolar damage (AU)

Comparison of microcomputed tomography, cone beam tomography, stereomicroscopy, and scanning electron microscopy techniques for detection of microcracks on root dentin and effect of different apical sizes on microcrack formation.

The aim of the study was to compare different imaging methods in the diagnosis of microcracks on root dentin and to evaluate the frequency of dentinal microcracks observed after root canal preparation using the ProTaper Universal (PTU) system of different sizes. A total of 30 mandibular molars' mesial roots were scanned with microcomputed tomography (micro-CT) and cone beam computed tomography (CBCT) imaging methods before instrumentation. Root canal instrumentation was performed up to PTU F2 and F4 files. After instrumentation stages, the roots were scanned again with micro-CT and then with CBCT in same parameters. All roots were sectioned horizontally at 2, 4, 6, 8, and 10 mm from the apices of the specimens. The sections were imaged under a stereomicroscope. Finally, imaging of the sections was done by scanning electron microscopy (SEM). Statistical data analysis of instrumentation steps was performed using Friedman and Wilcoxon tests, and the data of imaging methods were analyzed using Kruskal-Wallis and Mann-Whitney U tests (p = .05). Instrumentation with the PTU system up to F2 and F4 files significantly increased the number of microcracks compared with preoperative samples according to micro-CT imaging (p < .05). For detecting microcracks on the root dentin, there were no statistically significant differences between micro-CT (43.9%) and stereomicroscopy (45.8%) (p < .05). SEM showed significantly higher percentage of microcracks (88.3%) (p > .05). No microcrack was observed using the CBCT method. There were no statistically differences between micro-CT and stereomicroscopy. SEM showed more dentinal microcracks while no microcrack was observed with CBCT.

Prevalence of traumatic dental injury to the anterior teeth in children attending paramilitary and nonparamilitary schools in Nigeria.

Objective: The objective of this study was to determine the prevalence of traumatic dental injuries (TDIs) in the anterior teeth among children attending paramilitary and nonparamilitary schools in Benin City, Nigeria. Materials and Methods: A multistage sampling technique was used to select children aged 8-12 years with a previous history of trauma to the orofacial region. A self-administered questionnaire was then applied, and each participant was examined clinically. Data collected included demographic characteristics, etiology and place of injury, affected teeth, type of dental injury, lip competence, and overjet values. Analysis of data was done with the SPSS version 21.0 software. Pearson's Chi-squared test was used to determine the association between variables and odds ratio. Statistical significance was determined at P < 0.05. Results: A total number of 1352 children (mean age: 9.89 ± 1.4 years) were examined and 154 (11.4%) had a previous history of TDI. The prevalence among respondents in the paramilitary schools was 84 (6.2%) and those in nonparamilitary schools 70 (5.2%). Falls and play was the most common cause of TDI and was higher in children in paramilitary schools. Ellis Class I was the most prevalent type of injury in 91 (59.1%), tooth number 21 was the most traumatized, and the school environment was the most common place. Of the total number of respondents with TDI, the relationship between etiology with age, lip competence, and overjet was statistically significant (P < 0.05). Conclusion: The prevalence of TDI among the study participants was 11.4% and more in the paramilitary schools than the nonparamilitary.

RésuméObjectif: L'objectif de cette étude était de déterminer la prévalence des traumatismes dentaires traumatiques (TDI) dans les dents antérieures chez les enfants. fréquentant des écoles paramilitaires et non paramilitaires à Benin City, au Nigeria. Matériels et méthodes: Une technique d'échantillonnage en plusieurs étapes a été utilisée. utilisé pour sélectionner les enfants âgés de 8 à 12 ans ayant des antécédents de traumatisme dans la région orofaciale. Un questionnaire auto-administré a ensuite été appliqué, et chaque participant a été examiné cliniquement. Les données collectées comprenaient les caractéristiques démographiques, l'étiologie et le lieu de la blessure, dents affectées, type de lésion dentaire, compétence labiale et valeurs overjet. L'analyse des données a été réalisée avec le logiciel SPSS version 21.0. Le test du chi carré de Pearson a été utilisé pour déterminer l'association entre variables et odds ratio. La signification statistique a été déterminée à p <0,05. Résultats: Un nombre total de 1352 enfants (âge moyen: 9,89 ± 1,4 ans) ont été examinés et 154 (11,4%) avaient des antécédents de TDI. La prévalence parmi les répondants des écoles paramilitaires était de 84 (6,2%) et ceux des écoles non paramilitaires de 70 (5,2%). Des chutes et le jeu était la cause la plus fréquente de TDI et était plus élevé chez les enfants dans les écoles paramilitaires. Ellis Classe I était le type le plus répandu de blessures chez 91 personnes (59,1%), la dent numéro 21 était la plus traumatisée et le milieu scolaire le plus fréquent. Du nombre total des répondants avec TDI, la relation entre l'étiologie, l'âge, la compétence labiale et l'overjet était statistiquement significative (p <0,05). Conclusion: La prévalence du TDI chez les participants à l'étude était de 11,4% et plus dans les écoles paramilitaires que dans les écoles non paramilitaires.

Effect of Root Canal Preparation Techniques on Crack Formation in Root Dentin.

INTRODUCTION: The aim of this study was to assess the frequency of root crack formation caused by the use of manual instrumentation, 2 rotary systems, and 1 reciprocating system using light-emitting diode transillumination. METHODS: One hundred fifty mandibular premolars were randomly divided into 5 groups (n = 30): control 1, no intervention; control 2, instrumented with hand files; group 3, instrumented with ProTaper Universal rotary files (Dentsply Maillefer, Ballaigues, Switzerland); group 4, instrumented with OneShape rotary files (Micro-Mega, Besancon, France); and group 5: instrumented with the WaveOne reciprocal system (Dentsply Maillefer, Ballaigues, Switzerland). After root canal preparations, the roots were sectioned at 3, 6, and 9 mm from the apex with water irrigation. The slices were inspected under a stereomicroscope with light-emitting diode transillumination from the buccal, lingual, mesial, and distal directions at ×40 magnification to determine the presence/absence of cracks (dentinal defects). The chi-square test was used to analyze the data. RESULTS: There was a significant difference among the groups in crack frequency (P < .05). The 2 single systems had significantly higher cracks than the other 3 groups. At 3 mm from the apex, there were significantly more cracks in groups 4 and 5 than in groups 1, 2, and 3 (P < .05). At 6 mm from the apex, no significant difference was noted (P > .05). At 9 mm from the apex, the frequency of cracks in group 3 was significantly higher (P < .05). CONCLUSIONS: According to the results, using rotary instrumentation can result in some dentinal defects, and single-file systems, regardless of motion type, can cause significantly higher crack formation in the apical third of root canals.

Fracture toughening of peritubular microstructure in biological porous dentine.

Fracture behavior of biological porous dentine is important to the success of dental restoration. The role of peritubular dentine (PTD) microstructure on the fracture properties of human dentine is investigated by analysis of its crack tip shielding effect on microcracks and macrocracks. The evolution of microcracks around the dentine tubules (DTs) and the growth of macrocracks in the dentine are experimentally observed by scanning electron microscope. Two cases of an individual PTD&DT penetrating the microcrack tip and locating ahead of the microcrack tip are discussed. The effects of multiple PTD&DTs with random distribution and various porosities on the macrocrack shielding or amplifying in dentine are also particularly investigated. The importance of modulus, thickness of PTD and porosity of DT to the shielding effect of crack growth in dentine is studied by finite element analysis, which is characterized by the dominated fracture parameter J-integral. Numerical results demonstrate that PTD can shield the growth of dentine microcracks. When the PTD is in a specific location around macrocracks, it also has a shielding effect. The thicker and harder the PTD, the greater the shielding effect on crack growth. In conclusion, the porous dentine can be used as a reference structure in the design of implant dentures to enhance the dentine toughness.

Effect of Reciproc blue, XP-endo shaper, and WaveOne gold instruments on dentinal microcrack formation: A micro-computed tomographic evaluation.

The purpose of this study was to evaluate and compare the effect of Reciproc Blue (RPCB), XP-endo Shaper (XPS), and WaveOne Gold (WOG) single-files on dentinal microcrack formation using micro-computed tomography (micro-CT). Twenty-four mesial roots (24 mesio-buccal and 24 mesio-lingual canals) of mandibular molar teeth were prepared using RPCB, XPS, and WOG files (n = 8/each group). The samples were scanned with micro-CT in the pre- and post-preparation. Then, before preparation and after preparation cross-sectional images of the teeth were evaluated to detect the presence of microcracks. For each group, the number of microcracks was calculated as a percentage rate. The data were statistically analyzed using McNemar at 5% significance level (p < .05). Dentinal microcracks were observed in 25.99% (2,103 of 7,813), 31.99% (2,482 of 7,758), and 36.66% (2,836 of 7,731) of cross-sectional images of the XPS, WOG, and RPCB groups, respectively. In all the groups, all the dentinal microcracks seen in the post-treatment cross-sectional images were present in the corresponding pre-treatment images. Within the limitations of this study, the XPS, WOG, and RPCB files did not cause new dentinal microcrack formation or propagation of existing dentinal microcracks.

Dissecting dentine-pulp injury and wound healing responses: consequences for regenerative endodontics.

A thorough understanding of the biology of the dentine-pulp complex is essential to underpin new treatment approaches and maximize clinical impact for regenerative endodontics and minimally invasive vital pulp treatment (VPT) strategies. Following traumatic and carious injury to dentine-pulp, a complex interplay between infection, inflammation and the host defence responses will occur, which is critical to tissue outcomes. Diagnostic procedures aim to inform treatment planning; however, these remain clinically subjective and have considerable limitations. As a consequence, significant effort has focussed on identification of diagnostic biomarkers, although these are also problematic due to difficulties in identifying appropriate diagnostic fluid sources and selecting reproducible biomarkers. This is further compounded by the link between inflammation and repair as many of the molecules involved exhibit significant multifunctionality. The tertiary dentine formed in response to dental injury has been purposefully termed reactionary and reparative dentine to enable focus on associated biological processes. Whilst reactionary dentine produced in response to milder injury is generated from surviving primary odontoblasts, reparative dentine, in response to more intense injury, requires the differentiation of new odontoblast-like cells derived from progenitor/stem cells recruited to the injury site. These two diverse processes result in very different outcomes in terms of the tertiary dentine produced and reflect the intensity rather than specific nature (nonexposure versus exposure) of the injury. The subsequent identification of the odontoblast-like cell phenotype remains challenging due to lack of unique molecular or morphological markers. Furthermore, the cells ultimately lining the newly deposited dentine provide only a snapshot of events. The specific source and plasticity of the progenitor cells giving rise to the odontoblast-like cell phenotype are also of significant debate. It is likely that improved characterization of tertiary dentine may better clarify the influence of cell derivation for odontoblast-like cells and their diversity. The field of regenerative endodontics offers exciting new treatment opportunities, and to maximize outcomes, we propose that the term regenerative endodontics should embrace the repair, replacement and regeneration of dentine-pulp.

Activation of αSMA expressing perivascular cells during reactionary dentinogenesis.

AIM: To examine the contribution of perivascular cells expressing αSMA to reactionary dentinogenesis. METHODOLOGY: An inducible, Cre-loxP in vivo fate-mapping approach was used to examine the contribution of the descendants of cells expressing the αSMA-CreERT2 transgene to reactionary dentinogenesis in mice molars. Reactionary dentinogenesis was induced by experimental mild injury to dentine without pulp exposure. The Student's t test was used to determine statistical significance at *P ≤ 0.05. RESULTS: The lineage tracing experiments revealed that mild injury to dentine first led to activation of αSMA-tdTomato+ cells in the entire pulp chamber. The percentage of areas occupied by αSMA-tdTomato+ in injured (7.5 ± 0.7%) teeth were significantly higher than in teeth without injury (2 ± 0.5%). After their activation, αSMA-tdTomato+ cells migrated towards the site of injury, gave rise to pulp cells and a few odontoblasts that became integrated into the existing odontoblast layer expressing Col2.3-GFP and Dspp. CONCLUSION: Mild insult to dentine activated perivascular αSMA-tdTomato+ cells giving rise to pulp cells as well as a few odontoblasts that were integrated into the pre-existing odontoblast layer.

Influência de diferentes associações de fotoiniciadores nas propriedades fisico-químicas e mecânicas de adesivos experimentais zinco modificados / Influence of different photoinitiators associations in the physicochemical and mechanical properties of modified zinc experimental adhesives

A presença de água, bem como a ação das metaloproteinases (MMPs) são fatores que interferem na longevidade das restaurações adesivas. Diferentes associações de fotoiniciadores aos sistemas adesivos experimentais para aumentar a conversão de monômeros na presença de água e a incorporação de ZnOn (nanopartículas de óxido de zinco) como inibidor das MMPs vem sendo estudadas. Objetivo: Validar novos sistemas adesivos experimentais com diferentes associações de fotoiniciadores através de análises dos efeitos destas associações nas propriedades físico-químicas e mecânicas de sistemas adesivos zinco modificados. Material e Método: Modelos experimentais de adesivos na proporção HEMA/BISGMA 45/55 foram manipulados com diferentes acréscimos de fotoiniciadores hidrofílicos (hfi) e hidrofóbicos (hfo) nas proporções de 0,5% e 1% (CQ-hfo; EDMAB-hfo; DMAEMA-hfi; e DPIHP-hfi) acrescidos de nanopartículas de ZnO (1% em massa). Foram avaliadas as propriedades físicoquímicas e mecânicas: Grau de Conversão (GC), Resistência Frexural de três pontos (RF), Módulo de Elasticidade (ME), Sorção (SO) e Solubilidade (SOL) seguindo o padrão da ISO 4049. A análise dos resultados foi realizada através dos testes ANOVA 2 fatores e Tukey com nível de significância de 5%. Resultados: As diferentes associações de fotoiniciadores apresentaram diferenças estatisticamente significativas nos testes de GC, ME, e SOL, com os melhores resultados para os grupos G4SZn e G4CZn. Os adesivos contendo ZnOn apresentaram diferenças estatisticamente significantes nos testes de GC, ME e SOL, com os melhores resultados para o grupo G4CZn. Conclusões: a associação de fotoiniciadores hidrofílicos e hidrofóbicos nas formulações contribui para a melhora das propriedades físico-mecânicas de adesivos experimentais; a incorporação de óxido de zinco às formulações não compromete as propriedades desejadas dos sistemas adesivos experimentais e pode ser promissor no controle da degradação longitudinal(AU)

The presence of water as well as the action of metalloproteinases (MMPs) are factors that interfere in the longevity of adhesive restorations. Different associations of photoinitiators to experimental adhesive systems to increase the conversion of monomers in the presence of water and the incorporation of ZnOn (zinc oxide nanoparticles) as inhibitor of MMPs have been studied. Aim: To validate new experimental adhesive systems with different combinations of photoinitiators by analyzing the effects of these associations on the physicochemical and mechanical properties of modified zinc adhesive systems. Material and Method: Experimental models HEMA / BISGMA 45/55 adhesives were handled with different additions of hydrophilic (hfi) and hydrophobic (hfo) photoinitiators in the proportions of 0.5% and 1% (CQ-hfo; EDMAB-hfo; DMAEMAhfi; and DPIHP-hfi) plus ZnO nanoparticles (1% by mass). The physico-chemical and mechanical properties were evaluated: Degree of Conversion (DC), Frexural Strength (FS), Modulus of Elasticity (ME), Sorption (SO) and Solubility (SOL) in tests following the ISO 4049 standard. The analysis of the results was performed through the ANOVA 2 factor and Tukey tests with significance level of 5%. Results: The different associations of photoinitiators showed statistically significant differences in the DC, ME, and SOL tests, with the best results for the groups G4SZn and G4CZn. ZnO-doped adhesives showed statistically significant differences in the DC, ME and SOL tests, with the best result for the G4CZn group. Conclusions: the association of hydrophilic and hydrophobic photoinitiators in the formulations contributes to the improvement of the physical- mechanical properties of experimental adhesives; the incorporation of zinc oxide into the formulations does not compromise the desired properties of the experimental adhesive systems and may be promising in controlling longitudinal degradatio(AU)

Avaliação da incidência de micro trincas dentinárias após instrumentação reciprocante e rotatória / Evaluation of the incidence of dentin micro cracks after reciprocating and rotary instrumentation

Para que o tratamento endodôntico tenha sucesso, buscam-se meios de realizar uma limpeza eficiente e modelagem adequada do canal radicular. No entanto, na prática clínica, alguns problemas podem ser encontrados durante a instrumentação, sendo um deles a formação de micro trincas e linhas de fratura, que podem evoluir após o estresse causado pelas forças oclusais e resultar em uma fratura completa da raiz. O presente estudo teve por objetivo avaliar a incidência de micro trincas dentinárias em 48 incisivos inferiores humanos extraídos, utilizando estereomicroscópio e Tomografia Computadorizada de Feixe Cônico (TCFC), após o preparo do canal radicular com o sistema ProDesign S (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brasil) em movimento rotatório e reciprocante, o sistema ProDesign R (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brasil) em movimento reciprocante e o sistema Reciproc (VDW, Munich, Germany) em movimento reciprocante. Além disso, buscouse analisar a superfície dos instrumentos quando sem uso, após o primeiro uso, e sucessivamente até o terceiro uso, através de estereomicroscópio e microscopia eletrônica de varredura. Os resultados foram submetidos à análise estatística por meio da Prova de Friedman. Houve formação de micro trincas dentinárias em todos os grupos avaliados em Estereomicroscópio após o preparo do canal radicular utilizando o sistema ProDesign S em movimento rotatório e reciprocante, o sistema ProDesign R em movimento reciprocante e o sistema Reciproc em movimento reciprocante; porém sem diferenças estatisticamente significantes entre eles. Não foram observadas micro trincas dentinárias na análise em TCFC. Nenhum dos instrumentos analisados apresentou fraturas na superfície, porém ocorreu deformação por torção nas lâminas de corte após o terceiro uso na análise em Estereomicroscópio e MEV em todos os grupos. Na análise em MEV foram observadas trincas na superfície de instrumentos ProDesign S (em movimento rotatório) e ProDesign R (em movimento reciprocante) após o terceiro uso(AU)

So that the endodontic treatment is successful, means to achieve an efficient cleaning and proper modeling of root canal are sought. However, in clinical practice, some problems may be encountered during the instrumentation, one of them being the formation of micro cracks and lines of fracture, which may evolve after the stress caused by occlusal forces and result in a complete root fracture. The objective of this study is to evaluate the incidence of dentin micro cracks in 48 extracted human incisors using stereomicroscope and cone beam computed tomography (TCFC), after the root canal preparation with ProDesign S system (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil), in rotatory and reciprocating movement, ProDesign R system (Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) in reciprocating movement and Reciproc system (VDW, Munich, Germany) in reciprocating movement. In addition, it was aimed to analyze the instruments surface when without use, after first use, and successively until the third use, through a stereomicroscope and scanning electron microscopy. The results will be subjected to statistical analysis by means of the Friedman test. Dentin micro cracks were formed in all groups evaluated in a stereomicroscope after root canal preparation using the ProDesign S system in rotating and reciprocating motion, the ProDesign R system in reciprocating motion and the Reciproc system in reciprocating motion; but without statistically significant differences between them. No dentinal micro cracks were observed in the CBCT analysis. None of the instruments analyzed presented surface fractures, but torsional deformation occurred on the cutting blades after the third use in the stereomicroscope and SEM analysis in all groups. In the SEM analysis, cracks were observed on the surface of ProDesign S (rotating) and ProDesign R (reciprocating) instruments after the third use(AU)

Effect of Aging on Dentinal Crack Formation after Treatment and Retreatment Procedures: a Micro-CT Study.

In order to evaluate the volume of dentinal cracks taking into account the age of the dentin and the type of file system used for endodontic procedures, forty freshly extracted single-rooted lower incisive teeth presenting similar root volume, were divided into two groups according to the age of the patient: Group Young (18 - 30 years old) and Group Old (60 years old or more). Each specimen was scanned by microcomputed tomography (micro-CT) in three stages: (i) before any treatment, (ii) after endodontic treatment with Reciproc files (REC), and (iii) after subsequent endodontic retreatment. Each group was subdivided into two subgroups, according to the retreatment technique used: retreatment with REC or with ProTaper Universal Retreatment (PUR) files. For each subgroup, the images were analyzed for differences in the volume of dentinal cracks in the middle and apical thirds of the teeth , according to the dentin age. In both stages (before and after instrumentation), the micro-CT images of the old root dentin presented with higher volume of cracks than those of the young root dentin, statistical significance notwithstanding (p>0.01). The use of REC files appeared to have no statistically significant differences in the generation of cracks in any type of root dentin when compared with PUR files (p>0.01). When retreated with PUR, the old root dentin presented with a significantly higher volume of cracks (p<0.01) when compared with the old root dentin initially.

Effect of aging on dentinal crack formation after treatment and retreatment procedures: a micro-ct study

Abstract In order to evaluate the volume of dentinal cracks taking into account the age of the dentin and the type of file system used for endodontic procedures, forty freshly extracted single-rooted lower incisive teeth presenting similar root volume, were divided into two groups according to the age of the patient: Group Young (18 - 30 years old) and Group Old (60 years old or more). Each specimen was scanned by microcomputed tomography (micro-CT) in three stages: (i) before any treatment, (ii) after endodontic treatment with Reciproc files (REC), and (iii) after subsequent endodontic retreatment. Each group was subdivided into two subgroups, according to the retreatment technique used: retreatment with REC or with ProTaper Universal Retreatment (PUR) files. For each subgroup, the images were analyzed for differences in the volume of dentinal cracks in the middle and apical thirds of the teeth , according to the dentin age. In both stages (before and after instrumentation), the micro-CT images of the old root dentin presented with higher volume of cracks than those of the young root dentin, statistical significance notwithstanding (p>0.01). The use of REC files appeared to have no statistically significant differences in the generation of cracks in any type of root dentin when compared with PUR files (p>0.01). When retreated with PUR, the old root dentin presented with a significantly higher volume of cracks (p<0.01) when compared with the old root dentin initially.

Resumo Para avaliar o volume de fissuras dentinárias levando em consideração a idade da dentina e o tipo de sistema de limas utilizadas para procedimentos endodônticos, 40 dentes unirradiculares, incisivos inferiores, apresentando similar volume radicular, recentemente extraídos foram divididos em dois grupos de acordo com a idade do paciente: Grupo Jovem (18 a 30 anos) e Grupo Idoso (60 anos ou mais). Cada espécime foi scaneada por microtomografia computadorizada (micro-CT) em três estágios: (i) antes de qualquer tratamento, (ii) após tratamento endodôntico com limas Reciproc (REC) e (iii) após subsequente retratamento endodôntico. Cada grupo foi subdividido em dois subgrupos, de acordo com a técnica de retratamento utilizada: retratamento com REC ou com lima ProTaper Universal Retreatment (PUR). As imagens foram analisadas quanto às diferenças no volume das fissuras dentinárias nos terços médio e apical dos dentes de acordo com a idade da dentina. Em ambos os estágios (antes e depois da instrumentação), as imagens de micro-CT da dentina radicular idosa apresentaram maior volume de trincas do que as jovens, sem significância estatística (p>0.01). O uso das limas REC mostram não ter diferença estatística significante na geração de fissuras, em qualquer tipo de dentina, quando comparadas às limas PUR (p>0.01). Quando retratada com PUR, a dentina radicular idosa apresentou um volume de trincas significativamente maior (p<0.01) quando comparado com a dentina radicular idosa inicialmente.

Evaluación de microfracturas dentinarias después de la preparación con sistemas rotatorios y recíprocos. Estudio ex vivo / Evaluation of dentin microfractures after preparation with rotary and reciprocal endodontic instrumentation. An ex vivo study

El objetivo de este estudio fue comparar la frecuencia de microfracturas dentinarias después de la instrumentación con sistemas rotatorios y recíprocos. Se seleccionaron 50 incisivos inferiores, con un solo conducto. Se prepararon las cavidades de acceso y sellaron con Cavit(R). Cada raíz fue envuelta con una lámina de papel de aluminio, e incluida en resina acrílica autopolimerizable. Luego, se retiró la pieza de la resina, la hoja de aluminio e impresionó con silicona. La misma ocupó el espacio simulando el ligamento periodontal. Las muestras se dividieron al azar en cinco grupos de 10 piezas cada uno (n=10). Grupo 1: Control; Grupo 2: Sistema Mtwo(R); Grupo 3: Sistema RaCe(R); Grupo 4: Sistema Reciproc(R) y Grupo 5: Sistema WaveOne(R). Después de la preparación, las raíces fueron seccionadas horizontalmente a 3, 6 y 9 mm desde el ápice y observadas con microscopio estereoscópico a una magnificación de 30X. Se determinó la presencia de microfractura cuando la misma fue encontrada en 1 o más niveles. Se usó el Test Exacto con un nivel de significancia a=0,05. No se observaron defectos en el grupo 1. Todos los sistemas causaron microfracturas dentinarias, sin diferencias entre los grupos a los 3 mm, 6mm y 9mm. Las piezas preparadas por el sistema Reciproc fueron los que presentaron mayor frecuencia de microfracturas (30%), seguido por el sistema Mtwo y Race, cada uno con el 23% y finalmente, el sistema WaveOne con el 20%. Con excepción del grupo control, todos los grupos experimentales mostraron microfracturas. Aunque Reciproc mostró más grietas, no hubo diferencias entre los sistemas

The aim of this study was to compare the frequency of dentin microfractures after instrumentation with rotary and reciprocating systems. Fifty mandibular incisors with single canals were selected. Access cavities were prepared and sealed. Each root was wrapped with a single layer of aluminium foil and embedded in auto polymerizing resin. Aluminium foil was then peeled off. All roots were covered with a fine layer of silicon impression material simulating the periodontal ligament. Samples were randomly divided into five groups of 10 pieces each (n = 10). Group 1: Control; Group 2: Mtwo(R) System; Group 3: RaCe(R) System; Group 4: Reciproc (R) System and Group 5: WaveOne(R) System. After preparation, the roots were sectioned horizontally at 3, 6 and 9 mm from the apex. Samples were viewed under stereomicroscope at 30X magnification. The presence of microfracture was determined when it was found in 1 or more levels. The Exact Test was used with a level of significance a=0,05. No defects were observed in group 1. All systems caused dentinal microfractures, with no differences between groups at 3 mm, 6 mm and 9 mm. The pieces prepared with the Reciproc system were the ones with the highest microfracture frequency (30%), followed by the Mtwo and Race systems, each with 23% and finally the Waveone system with 20%. With the exception of the control group, all experimental groups showed microfractures. Although Reciproc showed more cracks, there were no differences between the systems

Periapical Microsurgery: Do Root Canal-retreated Teeth Have More Dentinal Defects?

INTRODUCTION: This microsurgical clinical study evaluated if teeth that have undergone endodontic retreatment are associated with more dentinal defects than primary root canal-treated teeth. METHODS: One hundred fifty-five patients who underwent periapical microsurgery treatment in a private practice setting were evaluated. The root ends were resected, and the roots were inspected for the presence of dentinal defects through the surgical operating microscope with the help of a 0.8-mm-diameter light-emitting diode probe light and methylene blue dye. The root canal treatment history (primary vs retreatment) of the teeth was documented and related to the presence or absence of dentinal defects. Bivariate analysis was performed using the chi-square test, and a multivariate analysis was performed using logistic regression to evaluate possible confounding effects of patient age, sex, and tooth location on the association between treatment and the presence of dentinal defects. RESULTS: Of the 155 treated teeth, 33 were excluded (3 fractured and 30 missing treatment history). Of the remaining 122 included teeth, 73 (59.8%) had undergone primary root canal treatment and 49 (40.2%) retreatment. Sixteen teeth (22.5%) of the primary root canal group versus 33 (64.7%) of the retreatment group had dentinal defects. The proportion of retreated teeth with dentinal defects compared with primary treatment was statistically significant (P < .001) with a higher proportion of retreated teeth having dentinal defects. In the multivariate analysis, only the type of treatment was statistically significant (P < .001). CONCLUSIONS: This clinical study showed that root canal-retreated teeth are associated with more dentinal defects than primary root canal-treated teeth.

Impact of glide path preparation on the incidence of dentinal defects after preparation of severely curved root canals.

OBJECTIVE: The purpose of this study was to evaluate the impact of glide path preparation on the incidence of dentinal defects after preparation of severely curved canals using ProTaper Next, F6 SkyTaper, and One Shape instruments. METHOD AND MATERIALS: One hundred and forty human mandibular molars with mesiobuccal canals with angles of curvatures ranging between 25 and 35 degrees and radii ranging between 4 and 9 mm were assigned to seven homogenous groups (n = 20 teeth per group). In half of the teeth of each of the seven groups a manual glide path (size 15) was created prior to instrumentation. The root canals were instrumented using the three different types of instruments to an apical size 25. One group served as control as no canal preparation was performed. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex and evaluated under a microscope using 25-fold magnification. The presence of dentinal defects (complete/incomplete cracks) was noted and analyzed using Fisher's exact test. RESULTS: No defects were observed in the controls. All canal preparations created dentinal defects. More incomplete and complete cracks were found in the apical (n = 4) and the middle (n = 3) canal third than in the coronal (n = 1), without any significant differences between the three instruments (P > .05). Prior glide path preparation had no significant impact on the incidence of dentinal defects (P > .05). CONCLUSION: A glide path preparation seems not to be mandatory to reduce the risk of dentinal defects formation when using the tested instruments in severely curved canals.