Accuracy of Magnetic Resonance Imaging in Clinical Endodontic Applications: A Systematic Review.

INTRODUCTION: The development of dedicated coils and new magnetic resonance imaging (MRI) sequences has led to an increase in image resolution and a reduction in artifacts. Consequently, numerous studies have demonstrated the utility of MRI as a nonionizing alternative to cone-beam computed tomographic imaging. The aim of this systematic review was to evaluate the accuracy of MRI in clinical applications in endodontics. METHODS: A literature search was conducted using PubMed, Embase, Scopus, and Web of Science. The inclusion criteria encompassed studies evaluating MRI applications in endodontics, covering tooth and root canal anatomy, root canal working length, pulp vitality and regeneration, the effect of caries on dental pulp, guided endodontics, periapical lesions, and root cracks/fractures. The selected studies examined both ex vivo and in vivo human teeth using clinical MRI units. Two researchers independently screened the studies, applied the eligibility criteria, and assessed the potential risk of bias using the revised QUADAS-2 tool (Bristol Medical School, University of Bristol, UK). RESULTS: A total of 18 studies were included in this systematic review, demonstrating that the use of MRI has a high diagnostic value in endodontics. In the evaluation of tooth and root canal anatomy, pulp vitality and regeneration, the effect of caries on dental pulp, periapical lesions, and root cracks/fractures, MRI's accuracy is comparable to or even higher than reference standards such as cone-beam computed tomographic imaging, micro-computed tomographic imaging, and histology. CONCLUSIONS: MRI has high potential accuracy for diagnosing various clinical endodontic tasks, except for root canal length, size of caries, and periapical lesion dimensions, which are overestimated in MRI.

Use of platelet concentrates in oral surgery of patients with osteonecrosis: a scoping review.

The objective of this study was to map, through a scoping review, the evidence available in the literature on the use of platelet concentrates in compromised patients undergoing oral surgeries. Searches were performed in electronic databases for clinical studies with compromised patients undergoing oral surgery who used platelet concentrates. Only studies published in English were included. Two independent researchers carried out the selection of studies. The study design and objective, surgical procedure and platelet concentrate used, systemic involvement, analyzed outcome, and main results were extracted. A descriptive analysis of the data was performed. Twenty-two studies met the eligibility criteria and were included. Case series was the most frequent study design among the included studies (41.0%). In terms of systemic disability, 19 studies reported patients with cancer and related to surgical treatment 16 studies reported patients underwent treatment for osteonecrosis related to the use of the drug. The most used platelet concentrate was pure platelet-rich fibrin (P-PRF). In general, most studies recommend the use of platelet concentrates. Thus, the results of this study suggest that the evidence related to the use of platelet concentrates in compromised patients when undergoing oral surgeries is still initial. Also, most studies assessed the use of platelet concentrates in patients with osteonecrosis.

Use of platelet concentrates in oral surgery of patients with osteonecrosis: a scoping review

Abstract The objective of this study was to map, through a scoping review, the evidence available in the literature on the use of platelet concentrates in compromised patients undergoing oral surgeries. Searches were performed in electronic databases for clinical studies with compromised patients undergoing oral surgery who used platelet concentrates. Only studies published in English were included. Two independent researchers carried out the selection of studies. The study design and objective, surgical procedure and platelet concentrate used, systemic involvement, analyzed outcome, and main results were extracted. A descriptive analysis of the data was performed. Twenty-two studies met the eligibility criteria and were included. Case series was the most frequent study design among the included studies (41.0%). In terms of systemic disability, 19 studies reported patients with cancer and related to surgical treatment 16 studies reported patients underwent treatment for osteonecrosis related to the use of the drug. The most used platelet concentrate was pure platelet-rich fibrin (P-PRF). In general, most studies recommend the use of platelet concentrates. Thus, the results of this study suggest that the evidence related to the use of platelet concentrates in compromised patients when undergoing oral surgeries is still initial. Also, most studies assessed the use of platelet concentrates in patients with osteonecrosis.

Resumo O objetivo do estudo foi mapear, através de uma revisão de escopo, as evidências disponíveis na literatura sobre o uso de agregrantes plaquetários em pacientes comprometidos e que realizaram cirurgias odontológicas. Pesquisas foram realizadas em bases de dados por estudos clínicos com pacientes comprometidos que realizaram cirurgia odontológica e usaram agragantes plaquetários. Apenas estudos em inglês foram incluídos. Dois pesquisadores independentes realizaram a seleção dos estudos. Os seguintes dados foram extraídos: desenho do estudo, objetivo, procedimento cirúrgico, agregante plaquetário usado, envolvimento sistêmico, desfecho analisado e principais resultados. Uma análise descritiva dos dados foi realizada. Vinte e dois estudos preencheram os critérios de elegibilidade e foram incluídos. Série de casos foi o desenho de estudo mais frequente entre os estudos incluídos (41,0%). Em relação ao comprometimento sistêmico, 19 estudos reportaram pacientes com câncer e em relação ao tratamento cirúrgico, 16 estudos reportaram pacientes que realizavam tratamento para osteonecrose relacionada ao uso de medicamentos. O agregante mais utilizado foi o plasma rico em fribina (P-PRF). Em geral, maioria dos estudos recomendou o uso dos agregantes plaquetários. Assim, os resultados desse estudo sugerem que a evidência relacionada ao uso de agregantes plaquetários em pacientes comprometidos que realizam cirurgia odontológica é ainda inicial. Ainda, a maioria dos estudos avaliaram o uso de agregantes plaquetários em pacientes com osteonecrose.

Effects of root canal enlargement on unprepared areas and coronal dentine thickness of three-rooted maxillary first premolars with different root configurations: A stepwise micro-CT study.

AIM: To evaluate the effects of progressive root canal enlargements on the unprepared surface area and remaining dentine thickness of three-rooted maxillary first premolars with different root configurations. METHODOLOGY: Thirty three-rooted maxillary first premolars with three root configurations (n = 10) were selected and scanned in a micro-CT device. The root canals were sequentially enlarged with rotary instruments sizes 30.02 (step 1), 30.04 (step 2) and 30.06 (step 3). After each step, a new scan was taken. Analysed parameters included morphometric measurements (length, volume and surface area), number of static voxels and minimal dentine thickness. Statistical analyses were performed with one-way anova post hoc Tukey tests and paired sample t-test at a significance level of 5%. RESULTS: No statistical differences were observed amongst groups regarding the morphometric parameters and static voxels (p > .05). The minimal dentine thickness of the distobuccal root significantly changed depending on the root configuration (p < .05), whilst no differences were observed in the other roots (p > .05). A great variation in the position of the minimal dentine thickness was observed after preparation. Overall, mean percentage reduction in dentine thickness was higher in the buccal roots than in the palatal root (p < .05). In the mesiobuccal and distobuccal root, the number of slices with minimal dentine thickness lower than 0.05 mm increases 2 to 3 times and 3 to 4 times, respectively, from steps 1 to 3. CONCLUSIONS: Instruments sizes 30.02 and 30.04 can be safely and effectively used to enlarge the buccal and palatal canals of three-rooted maxillary first premolars.

Root Canal Preparation Does Not Induce Dentinal Microcracks In Vivo.

INTRODUCTION: This in vivo study aimed to evaluate the development of dentinal microcracks after root canal preparation of contralateral premolars with rotary or hand instruments using micro-computed tomographic technology. METHODS: Sixty contralateral intact maxillary and mandibular premolars in which extraction was indicated for orthodontic purposes were selected and distributed into positive (n = 6, teeth with induced root microcracks) and negative (n = 6, intact teeth) control groups as well as 2 experimental groups (n = 24) according to the instrumentation protocol: ProTaper rotary (PTR) or ProTaper hand (PTH) systems (Dentsply Maillefer, Ballaigues, Switzerland). After root canal preparation, teeth were extracted using an atraumatic technique and scanned at a resolution of 17.18 µm. A total of 43,361 cross-sectional images of the roots were screened for the presence of dentinal microcracks. The results were expressed as the percentage and number of root section images with microcracks for each group. RESULTS: All roots in the positive control group showed microcracks at the apical third, whereas no cracks were observed in the specimens of the negative control group. In the PTR group, 17,114 cross-sectional images were analyzed, and no microcrack was observed. In the PTH group, dentinal microcracks were observed in 116 of 17,408 cross-sectional slices (0.66%) of only 1 specimen. These incomplete microcracks extended from the external root surface into the inner root dentin at the area of reduced dentin thickness. CONCLUSIONS: Root canal instrumentation with PTR and PTH instruments of contralateral maxillary and mandibular premolars did not result in the formation of dentinal microcracks in vivo.

Efficacy of 3 Supplementary Irrigation Protocols in the Removal of Hard Tissue Debris from the Mesial Root Canal System of Mandibular Molars.

INTRODUCTION: Instrumentation of the mesial root canal system of mandibular molars may hinder disinfection by packing hard tissue debris within the isthmuses. The removal of accumulated hard tissue debris (AHTD) by 3 supplemental irrigation systems, 2 ultrasonically activated and 1 multisonic, was assessed with micro-computed tomographic imaging. METHODS: Twenty-four extracted mandibular molars with 2 mesial canals connected by an isthmus and converging to a single foramen were selected. After preparation of the mesial canals with WaveOne Gold instruments (Dentsply Maillefer, Ballaigues, Switzerland), anatomically matched specimens were assigned to 3 final irrigation protocols (n = 8): intermittent ultrasonic (IU) with an ultrasonically energized 200-µm wire (Irrisafe; Satelec, Bordeaux, France), continuous ultrasonic (CU) with an ultrasonic irrigation needle (ProUltra PiezoFlow, Dentsply Maillefer), and GentleWave (GW) system (Sonendo Inc, Laguna Hills, CA). Specimens were scanned (SkyScan 1176; Bruker-microCT, Kontich, Belgium) at 17.18-µm pixel size before and after preparation and irrigation protocols. Data sets were coregistered, and the percentage reduction of AHTD calculated within the canals and isthmus for each specimen was statistically compared using 1-way analysis of variance and post hoc Tukey tests with a 5% significance level. RESULTS: The mean percentage reduction of AHTD in canals and isthmuses was significantly higher for GW (96.4% and 97.9%, respectively) than for CU (80.0% and 88.9%, respectively) (P < .05). AHTD reduction for IU (91.2% and 93.5%, respectively) did not differ significantly from GW and CU (P > .05). CONCLUSIONS: GW achieved greater efficacy in the removal of AHTD from the mesial root canal system of mandibular molars compared with CU but not IU. The efficacy of CU and IU was comparable.

Biomechanical behavior of maxillary premolars with conservative and traditional endodontic cavities.

OBJECTIVE: The objective was to evaluate the effects of the configuration of endodontic cavities with parallel or divergent walls, versus traditional endodontic cavities, on stress distribution, fracture resistance, and fracture mode of maxillary premolars by using both fracture-strength and finite element tests. METHOD AND MATERIALS: Thirty-two maxillary first premolars were divided into four groups (n = 8), according to the type of endodontic cavities: without endodontic cavities (control); conservative; conservative with diverging walls; and traditional. After performing root canal treatment and restoration, fracture resistance was evaluated by oblique compressive load. The stress distribution was evaluated by nonlinear finite element analysis by means of micro-computed tomography, operated at 50 kV and 800 mA. The fracture resistance data were analyzed by statistical software. RESULTS: Higher stress concentration was observed on the coronal portion of the palatal cusp and the palatal root dentin. Stress concentration on the palatal root dentin was similar for all groups. The stress level on the palatal cusp and at the proximal crests was slightly increased in the traditional endodontic cavities group compared with conservative endodontic cavities. Stress distribution in restored teeth was similar to that of intact teeth. No significant differences were observed in the fracture resistance among different endodontic cavities' design (P = .32). All groups had values similar to those of the control group (P > .05). CONCLUSIONS: Regardless of the cavity design, conservative endodontic cavities that preserve marginal ridge integrity did not affect the resistance to fracture, failure mode, or stress distribution in maxillary premolars restored with composite resin. Endodontically treated teeth displayed biomechanical behavior similar to sound teeth.

Fracture Strength of Weakened Anterior Teeth Associated to Different Reconstructive Techniques.

This study evaluated the fracture strength of endodontically treated teeth submitted to reconstructive techniques through dynamic and static tests. Forty human anterior teeth were divided into 4 groups (n=10): GNW (non-weakened) - root restored with glass fiber post (GFP), GW - weakened root restored with GFP, GDA - weakened root restored with direct anatomic GFP, and GIA - weakened root restored with indirect anatomic GFP. The teeth were endodontically treated considering that experimental groups (GW, GDA and GIA) simulated weakened roots for restoration with GFP using different techniques. The GFP was luted with resin cement and the coronal portion was restored with composite resin and metallic crowns. All samples were submitted to chewing simulation at 60 cycles/min in a total of 300,000 cycles. The survival samples were further exposed to compressive loading at a crosshead speed of 1.0 mm/min in a universal testing machine. The load was applied at 135° to the long axis of the tooth until failure. Data were analyzed by ANOVA (a=0.05). After chewing simulation were observed: GNW: 100% of survival roots; GW: 70% of survival roots, and GDA and GIA: 80% of survival roots. The mean fracture strength values (N) were 280.6 (GNW), 239.0 (GW), 221.3 (GDA), and 234.1 (GIA) without significant difference among the groups (p=0.7476). The results suggested similar fracture strength in both weakened and non-weakened teeth regardless the reconstructive technique of root internal wall. Higher incidence of catastrophic fracture was observed in weakened teeth without restoration of the root internal wall.

Fracture Strength of Weakened Anterior Teeth Associated to Different Reconstructive Techniques

Abstract This study evaluated the fracture strength of endodontically treated teeth submitted to reconstructive techniques through dynamic and static tests. Forty human anterior teeth were divided into 4 groups (n=10): GNW (non-weakened) - root restored with glass fiber post (GFP), GW - weakened root restored with GFP, GDA - weakened root restored with direct anatomic GFP, and GIA - weakened root restored with indirect anatomic GFP. The teeth were endodontically treated considering that experimental groups (GW, GDA and GIA) simulated weakened roots for restoration with GFP using different techniques. The GFP was luted with resin cement and the coronal portion was restored with composite resin and metallic crowns. All samples were submitted to chewing simulation at 60 cycles/min in a total of 300,000 cycles. The survival samples were further exposed to compressive loading at a crosshead speed of 1.0 mm/min in a universal testing machine. The load was applied at 135° to the long axis of the tooth until failure. Data were analyzed by ANOVA (a=0.05). After chewing simulation were observed: GNW: 100% of survival roots; GW: 70% of survival roots, and GDA and GIA: 80% of survival roots. The mean fracture strength values (N) were 280.6 (GNW), 239.0 (GW), 221.3 (GDA), and 234.1 (GIA) without significant difference among the groups (p=0.7476). The results suggested similar fracture strength in both weakened and non-weakened teeth regardless the reconstructive technique of root internal wall. Higher incidence of catastrophic fracture was observed in weakened teeth without restoration of the root internal wall.

Resumo Este estudo avaliou a resistência à fratura de dentes tratados endodonticamente submetidos a diferentes técnicas de reconstrução por meio de testes dinâmico e estático. Quarenta dentes humanos anteriores foram divididos em 4 grupos (n=10): GNW (não fragilizado): raiz restaurada com pino de fibra de vidro (PFV), GW: raiz fragilizada restaurada com PFV, GDA: raiz fragilizada restaurada com PFV anatômico direto, e GIA: raiz fragilizada restaurada com PFV anatômico indireto. Os dentes foram tratados endodonticamente considerando que nos grupos experimentais (GW, GDA e GIA) simulou-se fragilização radicular das raízes para restauração com PFV utilizando diferentes técnicas. Os PFV foi cimentados com cimento resinoso e a porção coronária foi restaurada com resina composta e coroa metálica. Todas as amostras foram submetidas a simulação de mastigação em 60 ciclos/min totalizando 300,000 ciclos. As amostras sobreviventes foram submetidas a teste de compressão com velocidade de 1,0 mm/min em máquina universal de ensaio. A carga foi aplicada a 135° em relação ao longo eixo do dente até a falha do dente. Os dados foram analisados por ANOVA (a=0,05). Após a simulação da mastigação foi observado: GNW: 100% de sobrevivência das raízes; GW: 70% de sobrevivência das raízes, e GDA e GIA: 80% de sobrevivência das raízes. O valor médio de resistência à fratura (N) foi de 280,6 (GNW), 239,0 (GW), 221,3 (GDA) e 234,1 (GIA) sem diferença significante entre os grupos (p=0,7476). Os resultados sugerem similar resistência à fratura em ambos os dentes fragilizados ou não-fragilizados em relação à técnica de reconstrução das paredes radiculares internas. Elevada incidência de fraturas catastróficas foram observadas nos dentes fragilizados sem a restauração das paredes radiculares internas.

Stress Distribution in Roots Restored with Fiber Posts and An Experimental Dentin Post: 3D-FEA.

The aim of this study was to compare the stress distribution in radicular dentin of a maxillary canine restored with either a glass fiber post, carbon fiber post or an experimental dentin post using finite element analysis (3D-FEA). Three 3D virtual models of a maxillary canine restored with a metal-ceramic crown and glass fiber post (GFP), carbon fiber post (CFP), and experimental dentin post (DP) were obtained based on micro-CT images. A total of 180 N was applied on the lingual surface of the incisal third of each tooth at 45 degrees. The models were supported by the periodontal ligament fixed in three axes (x=y=z=0). The von Mises stress (VMS) of radicular dentin and the intracanal posts was calculated. The structures of all groups showed similar values (MPa) and distribution of maximum von Mises stress. Higher stress was found in the apical third of dentin while the posts presented homogeneous stress distribution along the axis. The fiber and dentin posts exhibited similar stress values and distribution. Thus, the experimental dentin post is a promising restorative material.

Stress Distribution in Roots Restored with Fiber Posts and An Experimental Dentin Post: 3D-FEA

Abstract The aim of this study was to compare the stress distribution in radicular dentin of a maxillary canine restored with either a glass fiber post, carbon fiber post or an experimental dentin post using finite element analysis (3D-FEA). Three 3D virtual models of a maxillary canine restored with a metal-ceramic crown and glass fiber post (GFP), carbon fiber post (CFP), and experimental dentin post (DP) were obtained based on micro-CT images. A total of 180 N was applied on the lingual surface of the incisal third of each tooth at 45 degrees. The models were supported by the periodontal ligament fixed in three axes (x=y=z=0). The von Mises stress (VMS) of radicular dentin and the intracanal posts was calculated. The structures of all groups showed similar values (MPa) and distribution of maximum von Mises stress. Higher stress was found in the apical third of dentin while the posts presented homogeneous stress distribution along the axis. The fiber and dentin posts exhibited similar stress values and distribution. Thus, the experimental dentin post is a promising restorative material.

Resumo O objetivo deste estudo foi comparar a distribuição das tensões na dentina radicular de um canino superior restaurado com um pino de fibra de vidro, pino de fibra de carbono ou um pino experimental de dentina por meio do método dos elementos finitos tridimensional (MEF-3D). Três modelos virtuais 3D de um canino superior restaurado com coroa metaloce-râmica e pino de fibra de vidro (PFV), pino de fibra de carbono (PFC) e pino experimental de dentina (PD) foram obtidos baseados em imagens de micro-CT. Uma carga total de 180 N foi aplicada na superfície lingual do terço incisal de cada dente a 45 graus. Os modelos foram suportados pelo ligamento periodontal fixado em três eixos (x=y=z=0). Tensões equivalentes de von Mises (VMS) da dentina radicular e dos pinos intraradiculares foram calculadas. As estruturas de todos os grupos mostraram similar valor (MPa) e distribuição máxima de tensão de von Mises. Elevadas tensões foram encontradas no terço apical da dentina enquanto os pi-nos mostraram distribuição de tensões homogênea em seu longo eixo. Os pinos de fibra e de dentina apresentaram similar valor e distribuição de tensão. Assim, o pino experimental de dentina é um material reabilitador promissor.

Three-dimensional finite element analysis of endodontically treated teeth with weakened radicular walls restored with different protocols.

STATEMENT OF PROBLEM: The restoration of weakened roots with glass fiber posts (GFPs) remains a challenge. PURPOSE: The purpose of this study was to evaluate the stress distribution of endodontically treated teeth with weakened radicular walls restored with different protocols by 3-dimensional finite element analysis (3D-FEA). MATERIAL AND METHODS: The following 4 models of endodontically treated maxillary canines restored with metal ceramic crowns were simulated on the basis of computed microtomographic images to characterize the groups: GNW (control), a nonweakened root restored with a GFP; GW, a weakened root restored with a GFP; GDA, a weakened root restored with a direct anatomic GFP; and GIA, a weakened root restored with an indirect anatomic GFP. Loads of 180 N were applied to the lingual surface on the incisal third of the teeth at 45 degrees. The models were supported by a periodontal ligament and fixed in 3 axes (x=y=z=0). The von Mises stress (VMS) was calculated. RESULTS: All models exhibited VMS concentrations at the loading area and were distributed along the proximal surfaces of the root. The GFP exhibited a homogeneous stress distribution, and similar VMS distributions were observed in all of the reconstructive techniques. CONCLUSIONS: Similar stress distributions were observed in the endodontically treated teeth, regardless of root weakness and the reconstructive technique for the radicular walls.

Bond strength of restorative material to dentin submitted to bleaching and Er:YAG laser post-treatment.

OBJECTIVE: The purpose of this study was to assess the bond strength of a restorative material to bleached dentin, pretreated with Er:YAG laser. BACKGROUND DATA: Laser irradiation for dental surface treatment may increase the bond strength of restorative material to tooth surface. There are no reports of using Er:YAG laser on dentin bleached with 35% hydrogen peroxide. METHODS: Forty maxillary canines were sectioned, resulting in 80 fragments (5×5 mm) of intracoronary dentin that were divided into eight groups (n=10) according to the dental bleaching (present or not), surface conditioning (with or without laser) and the post-bleaching time to perform restoration (immediately or 7 days). The bleached specimens received two applications of 38% hydrogen peroxide. Er:YAG laser was applied for 20 sec with 400 mJ/15 Hz. Restorative procedure was performed using phosphoric acid, an adhesive system, and resin using a split Teflon matrix. The specimens were submitted to shear bond strength test and the data (MPa) were analyzed by ANOVA and Tukey's test (α=0.05). RESULTS: There were significant differences among the three factors (p<0.05). The highest values were obtained for unbleached specimens compared with bleached, for those treated with laser compared with those only conditioned with acid, and for those restored after 7 days compared with those having immediate restoration. In the interaction of factors, the bleached specimens treated with laser and restored immediately were statistically similar (p>0.05) to those bleached and restored after 7 days. CONCLUSIONS: Er:YAG laser can restore the bond strength of the dentin/restorative material interface even if the restoration is performed immediately after bleaching.

The finite element methods on oral rehabilitation: new for endodontically treated teeth / O método dos elementos finitos na reabilitação oral: novas perspectivas para dentes tratados endodonticamente

Objective: The aim of this study is to present the applicability of Finite Element Analysis (FEA) in oral rehabilitation, especially in endodontically treated teeth, based on its indication, methods, advantages and limitations through a literature review. Material and Methods: The search was conducted on National Library of Medicine’s Pub Med, Google search and Science Direct databases including the keywords “finite element analysis”, “oral rehabilitation” and “endodontics”. Results: A total of 412 articles were found, 42 were carefully selected by two subject matter experts for discussion including 21 articles focusing on the applicability of FEA to endodontically treated teeth. Conclusion: The FEA is a versatile, low-cost and efficient approach for reliable evaluation of complex structures, as oral rehabilitation treatments.

Objetivo: O objetivo deste estudo é apresentar a aplicabilidade do Método dos Elementos Finitos (MEF) na reabilitação oral, especialmente em dentes tratados endodonticamente, destacando sua indicação, métodos, vantagens e limitações por meio de uma revisão de literatura. Material e Métodos: A busca foi realizada na Biblioteca Nacional de Medicina do PubMed, pesquisa Google e Science Direct, incluindo as palavras-chave: “análise de elementos finitos”, “reabilitação oral” e “endodontia”. Resultados: Um total de 412 artigos foram encontrados, sendo que 42 foram cuidadosamente selecionados por dois especialistas no assunto para a discussão e incluídos 21 artigos com foco na aplicabilidade do MEF para dentes tratados endodonticamente. Conclusão: O MEF é uma abordagem versátil, de baixo custo e eficaz para avaliação de estruturas complexas, como tratamentos de reabilitação oral.

Healing of a tooth with an overinstrumented apex, extensive transportation and periapical lesion using a 5 mm calcium hydroxide apical plug: an 8-year follow-up report

Besides the risk of filling material extrusion throughout the apex, a satisfactory apical seal can be difficult to achieve in canals with open apices or iatrogenic enlargements of the apical constriction. These situations pose a challenge to root canal filling. This paper describes the root canal filling of a maxillary right canine with an overinstrumented apex, complete loss of the apical stop, extensive canal transportation and apical periodontitis. A 5 mm calcium hydroxide apical plug was placed before root canal filling. The plug was made by soaking paper points with saline, dipping the points in calcium hydroxide powder and then applying it to the apex several times, until a consistent apical plug was obtained. The canal was then irrigated with saline in order to remove any residual calcium hydroxide from the root canal walls, dried with paper points and obturated with an inverted #80 gutta-percha cone and zinc oxide-eugenol based sealer by the lateral condensation technique. An 8-year radiographic follow-up showed formation of mineralized tissue sealing the apical foramen, apical remodeling and no signs of apical periodontitis.

Além do risco de extrusão periapical de material obturador pelo ápice, pode ser difícil conseguir um bom selamento apical em dentes com rizogênese incompleta ou alargamentos iatrogênicos da constrição apical. Casos assim representam um desafio durante a obturação do canal. Este caso clínico descreve a obturação de um canino superior direito com perda total da constrição apical por sobreinstrumentação, transporte excessivo e lesão periapical. Antes da obturação foi feito um tampão apical de hidróxido de cálcio com 5 mm de extensão. Para a realização do tampão, pontas de papel absorvente foram umedecidas em soro fisiológico, levadas ao pó do hidróxido de cálcio para absorvê-lo e aplicadas várias vezes no ápice até se conseguir um tampão apical consistente. Em seguida o canal foi irrigado com solução salina para a remoção de eventuais resíduos de hidróxido de cálcio das suas paredes, secado com pontas de papel absorvente e obturado com um cone #80 de guta percha invertido e cimento obturador à base de óxido de zinco e eugenol pela técnica da condensação lateral. O acompanhamento radiográfico de 8 anos mostrou selamento apical por tecido mineralizado, remodelação do ápice e reparo da lesão periapical.

Bond strength of dentin submitted to bleaching and restored with different materials

Introduction: The use of adhesive composite resin with fluoride and with greater fluidity can be favorable to the restoration of the palatal/lingual face of teeth submitted to internal bleaching. Objective: This study evaluated the bond strength of adhesive systems and composite resins to bleached dentin. Material and methods:Forty maxillary canines were sectioned to obtain 40 blocks (5 x 5 mm) of intracoronary dentin. The fragments were included and bleached with 37% carbamide peroxide. After 7 days, the specimens were divided into two groups according to the adhesive system: with (Optibond Solo Plus) and without (Single Bond) fluoride and subdivided into 2 subgroups (n = 10) according to the composite resin: microhybrid (Z250) and flowable (Z350). The restoration was carried out through a bipartite matrix. After 24 hours, the specimens were subjected to shear bond strength test. The data (MPa) were analyzed by ANOVA and Tukey test (a = 0.05). Results: The best results (p < 0.05) were obtained for fluoridated adhesive (7.44 ± 2.35) compared with that without fluoride (5.36 ± 2.01); flowable resin (7.76 ± 2.23) performed better than microhybrid resin (5.03 ± 1.72). When the two variables were associated, the highest results were obtained for the specimens restored with fluoridated adhesive and flowable resin (9.04 ± 1.92). Lower results were observed for non-fluoridated adhesive + microhybrid resin - control (4.24 ± 1.59), without statistically significant differences when compared with the fluoridated adhesive + microhybrid resin (5.83 ± 1.52). Conclusion: The combination with fluoridated adhesive and flowable resin increases the shear bond strength of bleached dentin.

Influence of apical foramen lateral opening and file size on cemental canal instrumentation.

Since instrumentation of the apical foramen has been suggested for cleaning and disinfection of the cemental canal, selection of the file size and position of the apical foramen have challenging steps. This study analyzed the influence of apical foramen lateral opening and file size can exert on cemental canal instrumentation. Thirty-four human maxillary central incisors were divided in two groups: Group 1 (n=17), without flaring, and Group 2 (n=17), with flaring with LA Axxess burs. K-files of increasing diameters were progressively inserted into the canal until binding at the apical foramen was achieved and tips were visible and bonded with ethyl cyanoacrylate adhesive. Roots/files set were cross-sectioned 5 mm from the apex. Apices were examined by scanning electron microscopy at ×140 and digital images were captured. Data were analyzed statistically by Student's t test and Fisher's exact test at 5% significance level. SEM micrographs showed that 19 (56%) apical foramina emerged laterally to the root apex, whereas 15 (44%) coincided with it. Significantly more difficulty to reach the apical foramen was noted in Group 2. Results suggest that the larger the foraminal file size, the more difficult the apical foramen instrumentation may be in laterally emerged cemental canals.

Influence of apical foramen lateral opening and file size on cemental canal instrumentation

Since instrumentation of the apical foramen has been suggested for cleaning and disinfection of the cemental canal, selection of the file size and position of the apical foramen have challenging steps. This study analyzed the influence of apical foramen lateral opening and file size can exert on cemental canal instrumentation. Thirty-four human maxillary central incisors were divided in two groups: Group 1 (n=17), without flaring, and Group 2 (n=17), with flaring with LA Axxess burs. K-files of increasing diameters were progressively inserted into the canal until binding at the apical foramen was achieved and tips were visible and bonded with ethyl cyanoacrylate adhesive. Roots/files set were cross-sectioned 5 mm from the apex. Apices were examined by scanning electron microscopy at ×140 and digital images were captured. Data were analyzed statistically by Student’s t test and Fisher’s exact test at 5% significance level. SEM micrographs showed that 19 (56%) apical foramina emerged laterally to the root apex, whereas 15 (44%) coincided with it. Significantly more difficulty to reach the apical foramen was noted in Group 2. Results suggest that the larger the foraminal file size, the more difficult the apical foramen instrumentation may be in laterally emerged cemental canals.

Tendo em vista que a instrumentação do forame apical tem sido sugerida para a limpeza e desinfecção do canal cementário, a seleção do calibre do instrumento e a posição do forame apical representam passos desafiantes. Este estudo analisou a influência que a saída lateral do forame apical e o calibre do instrumento podem exercer na instrumentação do canal cementário. Trinta e quatro incisivos centrais superiores foram divididos em dois grupos: Grupo 1 (n=17), sem preparo cervical, e Grupo 2 (n=17), com preparo cervical com brocas LA Axxess. Limas K com aumentos de diâmetro foram progressivamente inseridas no canal até ajustar no forame apical e as pontas ficarem visíveis e foram fixadas com adesivo de etil cianoacrilato. Os conjuntos raízes/limas foram seccionados transversalmente a 5 mm aquém do ápice. Os ápices foram examinados por microscopia eletrônica de varredura com aumento de 140x e imagens digitais foram capturadas. Os dados foram examinados estatisticamente pelo teste t de Student e teste exato de Fischer com nível de significância de 5%. A microscopia eletrônica de varredura mostrou que 19 (56%) dos forames apicais saíram lateralmente em relação ao ápice radicular, enquanto que 15 (44%) coincidiram com ele. Dificuldade significantemente maior para chegar ao forame apical foi observada no Grupo 2. Os resultados sugerem que quanto mais calibroso for o instrumento foraminal, mais difícil poderá ser a instrumentação do forame apical em canais cementários que apresentam saída lateral.

Effect of high-concentrated bleaching agents on the bond strength at dentin/resin interface and flexural strength of dentin.

This study evaluated the effect of bleaching agents on bond strength at the dentin/resin interface and the flexural strength of dentin. Forty maxillary canines were selected for the study. In the shear strength test, 40 slabs of intracoronary dentin (5 x 5 mm) obtained from buccal surfaces of the crowns were included in acrylic resin. In the flexural strength test, 40 dentin bars (8 x 2 x 2 mm) were obtained from the roots. The 40 hemi-sections of the lingual surface were prepared for scanning electron microscopy (SEM). The specimens were divided into 4 groups according to the bleaching protocol (n=10): Unbleached (control), Sodium perborate + 20% hydrogen peroxide (SP + 20% HP), 37% carbamide peroxide (37% CP) and 38% hydrogen peroxide (38% HP). After 7 days, the bond strength specimens were restored and tested. Dentin bars were bleached and subjected to a three-point bending test. Data (MPa) were analyzed by ANOVA and Tukey's test (α=0.05). In the shear test, the control group was superior (p<0.05) to the bleached groups, which, in turn, were statistically similar (p>0.05). In the flexural strength test, the control group also had the highest values and differed significantly from the other groups (p<0.05). SEM revealed smear layer in all groups, with fissures in the bleached specimens. SP + 20% HP and 38% HP showed discontinuous interfaces with few tags. In conclusion, bond strength of restorative material to dentin and flexural strength of dentin were reduced after the use of high-concentration bleaching agents.