Esthetic rehabilitation with minimally invasive feldspathic ceramic veneers: 30 months of clinical follow-up / Reabilitação estética com facetas em cerâmicas feldspáticas minimamente invasivas: 30 meses de acompanhamento clínico

Diastemas among maxillary incisors and gingival contour disharmony are common findings among patients in dental practice. Ceramic veneers are indicated for esthetic rehabilitation of anterior diastemas due their predictable results, optical characteristics, fracture resistance and tooth structure conservation. However, because it is a friable material and have a brittle behavior, fractures occurrences are related to trauma, oclusal overload, parafunctional habits and material fatigue. This article describes 30 months follow-up of an esthetic and functional rehabilitation diastemas closure using feldspathic veneers associated with periodontal surgery and a ceramic repair with composite resin. Gingivectomy and frenectomy needs were found and the surgical procedures performed guided by new anatomic aspects of the crowns. Mock-up was performed after waxing and reverse planning. All anterior teeth underwent minimally invasive preparation. Feldspathic ceramic veneers were made, tried using try in paste and luted with light-cure resin cement. After 24 months, a fracture occurred on the right maxillary canine veneer. The ceramic restoration repair was performed with nano-hybrid composite resin, after the conditioning with 5% hydrofluoric acid, 37% phosphoric acid and silane couple agent. The combination between ceramic veneers and gingivectomy enables to obtain conservative treatments and esthetic success. After six months of the repair, resulting 30 months of follow-up, the anterior restorations were aesthetically and functionally satisfactory.

Presença de diastemas entre os incisivos superiores e desarmonia do contorno gengival são achados comuns entre os pacientes atendidos na rotina clínica. Facetas cerâmicas são indicadas para reabilitação estética de diastemas anteriores devido a previsibilidade de resultados, características óticas, resistências à fratura e conservação de estrutura dentária. Entretanto, por este ser um material frágil e apresentar comportamento friável, fraturas podem estar relacionadas a episódios de trauma, sobrecarga oclusal, hábitos parafuncionais e fadiga do material. Este artigo descreve um acompanhamento clínico de 30 meses de reabilitação estética e funcional de fechamento de diastema utilizando facetas minimamente invasivas confeccionadas com cerâmicas feldspáticas associadas à cirurgia periodontal e necessidade de reparo da cerâmica com resina composta. A indicação de plastia gengival e frenectomia foram constatadas e o procedimento cirúrgico guiado pelo planejamento da nova anatomia das coroas dentárias. Todos os dentes anteriores superiores foram minimamente preparados. O mock-up foi realizado depois do enceramento e do planejamento reverso. Facetas em cerâmicas feldspáticas foram confeccionadas, a cor do cimento resinoso selecionada com pastas testes e a cimentação concluída com cimento de polimerização exclusiva física. Depois de 24 meses de acompanhamento, ocorreu fratura da faceta do canino superior direito. O reparo da restauração cerâmica foi realizado com resina nanohibrida, depois da cerâmica condicionada com ácido fluorídrico 5%, ácido fosfórico 37% e aplicação de agente de união silano. A combinação entre facetas cerâmicas e cirurgia de plastia gengival permite alcançar tratamento conservador e sucesso estético. Posteriormente seis meses do reparo, resultando em 30 meses de acompanhamento clínico, as restaurações anteriores permaneciam estética e funcionalmente satisfatórias.

Micro-computed tomographic evaluation of removal and extrusion of root filling material during canal retreatment / Avaliação por meio de microtomografia computadorizada da remoção e extrusão de material obturador durante retratamento endodôntico

This study aimed to assess the efficiency of manual and rotary techniques for removing root filling material in endodontic treated canals and to evaluate the extrusion of debris via apical foramen. After access preparation, thirty human lower central incisors were instrumented, filled and divided into two groups (n=15): MNmanual retreatment technique; RT- rotary retreatment technique. The teeth were submitted to micro-computed tomographic scanning before and after the retreatment procedure, for quantifying the remaining filling material by relating the initial and final conditions. The analysis was conducted separately in all root thirds. The volume of material extruded through the apical foramen was also quantified. The data were statistically analyzed using t-test and two-way analysis of variance (ANOVA) at 5% of significance. No significant differences were detected between remaining filling material for the techniques evaluated (p=0.74), even considering the apical third only (p>0.75). Significant differences were found for the remaining filling material verified between the cervical third and middle/apical thirds, with lower values being observed at the cervical third for both groups (p<0.05). Apical extrusion of filling material was verified in seven specimens (2 from MN group and 5 from RT group). Both techniques showed similar performance for removing filling material from the root canal, considering the whole tooth or the root thirds independently. The apical extrusion of filling material observed was not sufficient to indicate which technique has increased tendency to induce more events during retreatments.

Este estudo objetivou avaliar a eficiência das técnicas manual e rotatória na remoção de material obturador de dentes tratados endodonticamente, além de verificar a extrusão de resíduos via forame apical. Após acesso endodôntico, trinta incisivos centrais inferiores humanos foram instrumentados, obturados e divididos em dois grupos (n=15): MN- técnica de retratamento manual; RT- técnica de retratamento rotatória. Os dentes foram submetidos à escaneamento micro-tomográfico previamente e após os procedimentos de retratamento para quantificação do remanescente de material obturador relacionando as condições inicial e final. Esta análise foi conduzida separadamente em todos os terços radiculares. O volume de material extruído via forame apical também foi quantificado. Os dados foram analisados estatisticamente por meio dos Testes T e de Análise de Variância em dois níveis com significância em 5%. Diferenças significantes não foram detectadas entre a quantidade de material remanescente para as duas técnicas avaliadas (p=0,74), mesmo considerando o terço apical separadamente (p>0.75). Diferenças significantes foram encontradas na quantidade de material remanescente verificado entre os terços cervical e médio/apical, com menores valores detectados no terço cervical para ambos os grupos (p<0.05). Extrusão apical de material obturador foi identificada em sete espécimes (2 do grupo MN e 5 do grupo RT). As duas técnicas avaliadas apresentaram desempenho similar na remoção do material obturador do canal radicular, considerando o dente como um todo ou os terços radiculares separadamente. A extrusão apical de material obturador verificada não foi suficiente para indicar qual técnica possui maior tendência de promover eventos durante o retratamento.

Periodontal and Restorative Treatment of Gingival Recession Associated with Non-Carious Cervical Lesions: Case Study.

The association between the presence of gingival recession and non-carious cervical lesions is a common finding in dentistry. These diseases have multifactorial etiology and the treatment should be multidisciplinary. Although traditionally the majority of professionals treat non-carious cervical lesions only with conventional restorative procedures, in most cases a combination of periodontal and restorative treatments provides the best functional and esthetic results. Thus, the objective of this case report was to present a new option for treatment, which consists of a subepithelial connective tissue graft associated with a coronally advanced flap placed on dentin and non-carious cervical lesions restored with lithium disilicate partial veneers. A patient complaining about the esthetic aspects of her teeth and cervical dentin hypersensitivity was submitted to occlusal adjustments and daily diet analysis in order to manage etiologic factors. Experienced operators then performed restorative and surgical treatments. Periodontal clinical attachment level (probing depth + gingival margin), bleeding on probing, plaque index, and the integrity of the restorations were observed. During the monitoring period, the treatment was effective, with good functional and esthetic results. The hypersensitivity disappeared, and neither inflammatory characteristics in gingival tissue nor failures in restorations were noted. It might be concluded that treatment with a combination of techniques can be effective and predictable for patients with gingival recession and non-carious cervical lesions that may or may not require restorative procedures under controlled conditions.

Influence of flexion angle of files on the decentralization of oval canals during instrumentation.

The aim of this study was to evaluate the influence of the flexion angle of files on the decentralization of root canals during instrumentation. Fifteen lower incisors were instrumented with Protaper Universal files and radiographed in two directions (mesiodistal and buccolingual) before and after instrumentation with a #15 K-file in position for evaluating the flexion angle of files. The specimens were also scanned before and after instrumentation using micro-computed tomography to obtain the canal area and the distance from the center position of the file to the canal walls. Sections located 1.0 mm (end of the canal), 3.0 mm (apical third), 9.0 mm (middle third), and 15.0 mm (cervical third) from the apex were verified. After instrumentation, the flexion angles of files decreased by an average of 0.76º in the buccolingual direction and 1.92º in the mesiodistal direction (p < 0.001); the canal area increased by an average of 0.58, 0.37, 0.23 and 0.13 mm(2) from the cervical to the end of the root canal (p < 0.001). Non-instrumented areas were observed on the buccal and lingual walls, and effective action of files was determined on the mesial and distal walls. The sections from the end of the canal showed canal deviation toward the lingual wall, whereas the other sections showed deviation toward the buccal wall. The flexion angles of files influence the final shape of the root canal, resulting in file decentralization along the pathway of the canal.

Multidisciplinary treatment of congenitally missing maxillary lateral incisors: a case report / Tratamento multidisciplinar de agenesias de incisivos laterais superiors: relato de caso

Congenital tooth agenesis and tooth loss due to dental traumatism are some of the most common causes leading to rehabilitation of young patients with dental implants. The success of treating congenitally missing teeth with implant-supported prosthesis is no more guided only by osseointegration criteria. Nowadays the successful rehabilitation of these cases involves the adequate installation of dental implants with suitable prosthetic contour, color, and emergence profile closer to that found in natural dentition. Several treatment options are available for restoring patients with congenitally missing teeth such as maxillary lateral incisors. Fixed prosthodontics and orthodontics managements are considered acceptable treatment protocols. However, the gold standard rehabilitation of congenitally missing maxillary incisors is performed with implant-based prosthesis since no tooth wear neither extensive tooth movements are necessary. The present paper reports the treatment of a young adult woman with congenitally missing maxillary lateral incisors who underwent orthodontic treatment for improvement of teeth alignment and occlusal balance previous to dental implant surgery. This treatment also allowed appropriate space for the future lateral incisors crowns. Then, Morse-type conical implants were positioned and prosthetic abutments installed. Ceramic laminates were planned on central incisors in order to improve anterior aesthetics. All-ceramic crowns and laminates were made using lithium dissilicate-based ceramic (e-Max Press). The multidisciplinary association of orthodontic, implant and prosthetic techniques resulted in successful functional and aesthetic rehabilitation of the case, which was maintained after 1 year follow up.

Agenesias e perdas dentárias devido a traumatismos estão entre as principais causas de reabilitações de pacientes jovens com implantes dentários. O sucesso do tratamento de agenesias com implantes osseointegrados não se limita mais à osseointegração exclusivamente. Atualmente, o sucesso da reabilitação destes casos envolve a correta instalação de implantes que favoreçam a confecção de uma prótese com cor, forma e perfil de emergência o mais semelhante possível aos dentes naturais. Os cirurgiões-dentistas têm várias opções para tratar casos de agenesias como as de incisivos laterais superiores. Próteses fixas convencionais e movimentação ortodôntica são considerados protocolos de tratamento aceitáveis. Entretanto, agenesias de incisivos laterais superiores são reabilitadas satisfatoriamente com próteses sobre implantes uma vez que extensas movimentações ou desgastes dentários são necessários. O presente caso relata o tratamento de uma paciente jovem com agenesia dos incisivos laterais que havia feito tratamento ortodôntico para correção do posicionamento dentário e equilíbrio dental antes de se submeter à cirurgia para instalação de implantes. O tratamento ortodôntico também favoreceu a obtenção de espaço apropriado para instalação das coroas dos incisivos laterais. Posteriormente, implantes cônicos com plataforma protética tipo cone morse foram instalados e pilares selecionados. Laminados cerâmicos foram planejados para os incisivos centrais com objetivo de se promover um resultado final mais harmônico e estético. As coroas em cerâmica pura e laminados foram confeccionados com cerâmica a base de dissilicato de lítio (e.Max Press). A associação multidisciplinar entre tratamento ortodôntico, implantes e próteses sobre implantes resultou no sucesso funcional e estético da reabilitação do presente caso com acompanhamento clínico de uma ano.

Enxerto de tecido conjuntivo subepitelial otimizando a reabilitação oral com implantes osseointegrados / Connective tissue graft improving implant oral rehabilitation

A estética tem sido um fator indispensável, tanto no direcionamento quanto no desenvolvimento da Odontologia, assim como na Implantodontia. Além da boa qualidade e anatomia da prótese que substituirá o dente perdido, a aparência saudável e harmônica do tecido peri-implantar é preponderante no tratamento reabilitador final. A estratégia de substituição de dentes anteriores com próteses sobre implantes pode envolver procedimentos multidisciplinares. As técnicas cirúrgicas de plástica peri-implantar são amplamente aplicadas com previsibilidade naquelas situações clínicas que demandam volume, forma e qualidade dos tecidos moles ao redor dos implantes. Sob esse ponto de vista, o enxerto de tecido conjuntivo subepitelial tem sido empregado com alto índice de sucesso, para obtenção de estética, função e saúde da mucosa peri-implantar.

Influence of flexion angle of files on the decentralization of oval canals during instrumentation

The aim of this study was to evaluate the influence of the flexion angle of files on the decentralization of root canals during instrumentation. Fifteen lower incisors were instrumented with Protaper Universal files and radiographed in two directions (mesiodistal and buccolingual) before and after instrumentation with a #15 K-file in position for evaluating the flexion angle of files. The specimens were also scanned before and after instrumentation using micro-computed tomography to obtain the canal area and the distance from the center position of the file to the canal walls. Sections located 1.0 mm (end of the canal), 3.0 mm (apical third), 9.0 mm (middle third), and 15.0 mm (cervical third) from the apex were verified. After instrumentation, the flexion angles of files decreased by an average of 0.76º in the buccolingual direction and 1.92º in the mesiodistal direction (p < 0.001); the canal area increased by an average of 0.58, 0.37, 0.23 and 0.13 mm2 from the cervical to the end of the root canal (p < 0.001). Non-instrumented areas were observed on the buccal and lingual walls, and effective action of files was determined on the mesial and distal walls. The sections from the end of the canal showed canal deviation toward the lingual wall, whereas the other sections showed deviation toward the buccal wall. The flexion angles of files influence the final shape of the root canal, resulting in file decentralization along the pathway of the canal.

Substituição de implante perdido por peri-implantite e reabilitação multidisciplinar em 18 meses: acompanhamento de um ano / A 18-month multidisciplinary rehabilitation period for a dental implant replacement due to peri-implantitis – 1 year follow-up

O presente caso clínico relata a perda de um implante devido à peri-implantite, cuja ocorrência foi favorecida pelo mau posicionamento do mesmo. Dessa forma, a coroa e o implante foram removidos, por ausência de possibilidade de outro tratamento mais conservador. Com o auxílio de técnicas cirúrgicas de enxerto ósseo (autógeno e xenógeno), enxerto gengival (conjuntivo subepitelial), tratamento ortodôntico e confecção de novas próteses, a saúde e a estética da paciente foram restabelecidas. Para a substituição, foi utilizado um implante cone-morse, amplamente utilizado em áreas estéticas atualmente. O tratamento durou 18 meses, atingindo as expectativas da paciente. Concluiu-se que a abordagem multidisciplinar e a comunicação entre os profissionais são essenciais para o sucesso do tratamento, uma vez que a instalação de implantes, sem planejamento protético minucioso, pode resultar em uma quantidade inumerável de problemas e complicações, no que diz respeito aos resultados cirúrgicos e protéticos esperados.

This case reports on the loss of a dental implant due to peri-implantitis favored by its malpositioning. In this way, the defi nitive crown and implant were removed because a more conservative treatment was not possible. With the aid of surgical techniques as bone grafting (autogenous and xenogeneic), gingival grafts (subepithelial connective tissue), orthodontic treatment and fabrication of new prostheses, the health and esthetic aspects were retrieved. A new dental implant (Cone Morse type) was inserted as advocated for esthetic regions. After 18 months, patient expectations were achieved. It can be concluded that a multidisciplinary approach and communication among different specialists are fundamental for a successful treatment once incorrect implant placement can generate a myriad of problems and complications regarding the surgical and prosthetic expected outcomes.

Critical instrumentation area: influence of root canal anatomy on the endodontic preparation.

The aim of this study was to evaluate the root canal anatomy of mandibular incisors before and after endodontic instrumentation, identifying regions inaccessible to the action of files (Critical instrumentation Area - CA) in a three-dimensional perspective. Thirty human mandibular central incisors were selected, assigned to two groups (n=15) and instrumented using ProTaper Universal rotary files. In the RX group, longitudinal digital radiographic images were obtained in the buccolingual (BL) and mesiodistal (MD) views. In the CT group, cross-sectional micro-computed tomography (µCT) images were obtained at 3, 9 and 15 mm from the apex. The canal area of the specimens was evaluated before and after instrumentation using digital images from each group. Data were analyzed using t-test, one-way ANOVA with subdivided parcels and Tukey's test (α=0.05). The canal area found in the MD radiographs was larger than in the BL radiographs, which was also confirmed in the transversal images (p<0.01). The CA was only detected in the MD radiographs and µCT scans. On the root canal configuration, a continuous reduction in the canal conicity was observed in BL radiographs, while in MD view there was a constriction at the cervical third and subsequent increase at the middle third (p<0.01). The conical shape of the root canal was observed only in the BL view. The canal enlargement in BL radiographs was not indicative of homogeneous instrumentation, since unprepared areas (CA) were also verified on the buccal and lingual walls in different images.

Biocompatibility of three bioabsorbable membranes assessed in FGH fibroblasts and human osteoblast like cells culture.

OBJECTIVES: Specific physical and chemical features of the membranes may influence the healing of periodontal tissues after guided tissue regeneration (GTR). The aim of the present investigation was to analyze the biological effects of three bioabsorbable membranes. The hypothesis is that all tested membranes present similar biological effects. METHODS: Human osteoblast like-cells (SaOs-2) and gingival fibroblasts FGH (BCRJ -RJ) were cultured in DMEM medium. The viability of the cells cultured on the membranes was assesses using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). Quantitative determination of activated human Transforming Growth Factor beta 1 (TGF-ß1) on the supernatants of the cell culture was observed. Samples were examined using scanning electron microscope (SEM). RESULTS: SaOs2, in 24 hours, PLA group showed higher values when compared to other groups (P < 0.05). All groups presented statistical significance values when compared two times. In 4 h and 24 h, for the fibroblasts group, significantly difference was found to PLA membrane, when compared with the other groups (p < 0.05). For TGFß1 analyzes, comparing 4 and 24 h, for the osteoblast supernatant, COL1 and PLA groups showed statistically significant difference (p <0,008). On the analysis of culture supernatants of fibroblasts, in 24 hours, only PLA group presented significant difference (p = 0,008). CONCLUSIONS: The biomaterials analyzed did not show cytotoxicity, since no membrane presented lower results than the control group. PLA membrane presented the best performance due to its higher cell viability and absorbance levels of proliferation. Both collagen membranes showed similar results either when compared to each other or to the control group.

Critical Instrumentation Area: Influence of Root Canal Anatomy on the Endodontic Preparation

The aim of this study was to evaluate the root canal anatomy of mandibular incisors before and after endodontic instrumentation, identifying regions inaccessible to the action of files (Critical instrumentation Area - CA) in a three-dimensional perspective. Thirty human mandibular central incisors were selected, assigned to two groups (n=15) and instrumented using ProTaper Universal rotary files. In the RX group, longitudinal digital radiographic images were obtained in the buccolingual (BL) and mesiodistal (MD) views. In the CT group, cross-sectional micro-computed tomography (µCT) images were obtained at 3, 9 and 15 mm from the apex. The canal area of the specimens was evaluated before and after instrumentation using digital images from each group. Data were analyzed using t-test, one-way ANOVA with subdivided parcels and Tukey's test (α=0.05). The canal area found in the MD radiographs was larger than in the BL radiographs, which was also confirmed in the transversal images (p<0.01). The CA was only detected in the MD radiographs and µCT scans. On the root canal configuration, a continuous reduction in the canal conicity was observed in BL radiographs, while in MD view there was a constriction at the cervical third and subsequent increase at the middle third (p<0.01). The conical shape of the root canal was observed only in the BL view. The canal enlargement in BL radiographs was not indicative of homogeneous instrumentation, since unprepared areas (CA) were also verified on the buccal and lingual walls in different images.

Este estudo avaliou a anatomia do canal radicular de incisivos inferiores, antes e após a instrumentação endodôntica, identificando regiões inacessíveis à ação das limas (Área Crítica de instrumentação - AC), em uma perspectiva tridimensional. Trinta incisivos centrais inferiores humanos foram selecionados, divididos em dois grupos (n=15), e instrumentados usando limas rotatórias ProTaper Universal. No grupo RX, imagens longitudinais foram obtidas em duas incidências, vestíbulo-lingual (VL) e mésio-distal (MD), por meio de radiografias digitais. No grupo CT, imagens transversais foram obtidas por meio de microtomografia computadorizada (μTC), em secções localizadas a 3 mm, 9 mm, e 15 mm do ápice. A área do canal das amostras foi avaliada antes e após a instrumentação usando as imagens digitais de cada grupo. Os dados foram analisados por meio do teste t, ANOVA a um critério com parcela subdividida e ao teste de Tukey (α=0,05). A área de canal encontrada nas radiografias MD foi maior do que nas radiografias VL, o que também foi confirmado nas imagens transversais (p<0,01). A Área Crítica de instrumentação só foi detectada nas radiografias MD e nas seções de μTC. Na configuração de canal, a redução contínua na conicidade do canal foi observada nas radiografias VL, enquanto na incidência MD, houve uma constrição no terço cervical e um subsequente aumento no terço médio (p<0,01). A forma cônica do canal radicular foi observada somente na visão VL. O alargamento do canal verificado nas radiografias VL não foi indicativo de instrumentação homogênea, uma vez que áreas não instrumentadas (AC) foram observadas nas paredes vestibular e lingual em visões distintas.

Critical analysis of fiber post surface treatment: a review / Análise crítica do tratamento de superfície de pinos de fibra: uma revisão

The surface treatment of fiber posts influence the bonding between composite resin cements and intraradicular retainers, being relevant to the prognostic of teeth without coronal structure. This study aimed to evaluate the different fiber post surface treatment protocols described on literature. The search strategy included a review of PubMed/MEDLINE database using fiber post associated with adhesion; bonding; surface treatment; as keywords. Papers not comprehending English language; assessment of post surface treatment; or testing of materials and their physicmechanical properties were excluded. Studies about glass and quartz fiber post surface treatment were considered for this literature review. Among the 190 articles included, silane agent was the material most used (60.52%) for the surface treatment of fiber posts, followed by application of alcoholic solutions (38.29%), and primer and/or adhesive systems (36.84%). Sandblasting of post surface was mentioned in (17.89%), but it affected the physical and mechanical properties. Hydrogen peroxide was mentioned only in 5.78% and it was shown to result on adequate exposure of the glass fibers without damaging them. It was concluded that a consensus for fiber post surface treatment still not exist in the current literature. Among the protocols described, the one using hydrogen peroxide followed by application of silane seems the most promising, since it allows increased bond strengths without fiber damage.

O processo de tratamento da superfície de pinos pré-fabricados de fibra influencia na união entre cimentos resinosos e esses retentores intra-radiculares, sendo relevante para o prognóstico do tratamento restaurador de dentes sem remanescente coronário. Este estudo objetivou avaliar diferentes protocolos de tratamentos de superfície para pinos de fibra descritos na literatura. Como metodologia, realizou levantamento bibliográfico na plataforma PubMed/MEDLINE, com a palavras-chave fiber post associada à adhesion; bonding; surface treatment. Excluíram-se artigos não redigidos em inglês; que não trataram a superfície do pino; e testes de propriedades físicas-mecânicas. Estudos que trataram a superfície de pinos de fibra de quartzo ou vidro foram incluídos. Dentre os 190 artigos incluídos nesta revisão, o agente silano foi o material mais utilizado (60.52%) para tratamento de superfície de pinos de fibra, seguido pela aplicação de álcool (38.29%), e sistema adesivo (36.84%). O jateamento do pino foi mencionado em 17.89%, mas esta técnica resultou em alteração das propriedades físicas e mecânicas. O peróxido de hidrogênio foi mencionado em 5.78% dos manuscritos, entretanto este tratamento permite a adequada exposição das fibras sem danificá-las. Concluiu-se que não consta na literatura protocolo padrão do tratamento da superfície de pinos de fibra. Dentre os protocolos descritos, o protocolo utilizando peróxido de hidrogênio seguido da aplicação do silano aparece como o mais promissor, pois permite resistência de união aumentada sem promover danos as fibras.

Assessment of influence of flexion angles of files in apical stop preparation by using manual and rotary instrumentation techniques.

INTRODUCTION: This study aimed to evaluate the influence of flexion angles produced by files during root canal instrumentation on the final form of the apical stop. METHODS: Sixty human lower incisors were divided into 3 groups (n = 20). After access preparation and working length determination, radiographs were taken from a mesiodistal and buccolingual direction with #15 K-file inserted to working length. Teeth from FlexM group were instrumented with stainless steel Flexofiles up to #40 file. For ProM and ProR groups, hand ProTaper Universal and ProTaper Universal rotary files were used, respectively, up to file F4. New radiographs were taken as previously described. After gutta-percha insertion, the apex of each specimen was ground, allowing gutta-percha visualization, and an image of the apex was captured to identify root canal deformation with computer software. The flexion of files was evaluated from both initial and final radiographs as the angle formed between the divergence of the file path and its virtual image represented by the direction taken by the file in the absence of curvature. RESULTS: FlexM group presented the highest variation in flexion angles compared with ProM (P = .112) and ProR (P = .024) groups. Nickel-titanium rotary system (ProR) reduced apical stop deformation compared with the manual techniques that used nickel-titanium (P = .011) or stainless steel (P = .025) files. CONCLUSIONS: Force vectors caused by the flexion angles of the files during the instrumentation of curved canals promoted apical stop deformation. ProTaper Universal rotary files showed less apical deformation than hand ProTaper Universal and stainless steel files.

Influence of core-finishing intervals on tensile strength of cast posts-and-cores luted with zinc phosphate cement

The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.

Influence of core-finishing intervals on tensile strength of cast posts-and-cores luted with zinc phosphate cement.

The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.