In Vitro Comparative Study Of The Influence Of Instrument Taper On The Fracture Resistance Of Endodontically Treated Teeth

Context: Preparation of the root canal system is recognized as being one of the most important stages in root canal treatment which removes organic debris and microorganisms from the root canal system by means of chemico- mechanical preparation and irrigation of the canals. The use of nickel-titanium instruments has drastically reduced the time and the difficulties that were encountered with traditional hand instruments made up of stainless steel. Utilizing properties of super-elasticity, shape memory and different tapers of these instruments reduces not only the possibility of canal transportation but also affects both the geometry and volume of root canals. This subjects the root dentin to stress and consequently dentinal defects which increases the risk of root fracture during or after root canal treatment. Clinicians now have the opportunity to choose from differently tapered instruments having unique characteristics in their geometry and metallurgy. These are progressively tapered instruments, fixed tapered instruments, and variable tapered instruments, which come with the benefit of conforming to the root canal anatomy as well as removing dentin as little as possible while cleaning and shaping. The aim of this study was to examine the influence of instrument taperAim: on the fracture resistance of endodontically treated roots under in vitro experimental conditions.Conclusion: Under the limitations of this study in in-vitro conditions there were no significant differences between the fracture loads between the different file systems used, however samples prepared with Hyflex EDM recorded the highest fracture resistance, followed by ProTaper NEXT, ProTaper Gold and NeoEndo Flex respectively.

Mechanical Behavior of Radial Support of a Novel Balloon Expandable Tapered Stent / 医用生物力学

Objective To explore influences of the taper and connecting rib form on supporting performance of the stent, and provide an important scientific basis for structural design and clinical selection of the tapered stent. Methods A nonlinear finite element model for radial support performance of a novel balloon-expandable tapered stent was constructed, and the radial stiffness (RS) and stress distributions of the stent at different tapers (0°, 0.565°and 1.13°) and with different structural forms of stent linker (V-shape, I-shape, C-shape, S-shape, M-shape) were analyzed by plane compression. The relationship between structural design of the vascular stent and its radial support performance was studied. Results The RS of 0°stent, 0.565°stent, 1.13° stent was 2.51, 1.61, 0.85 N/mm, respectively. The RS of 0.565°stent and 1.13° stent was 35.86% and 66.14% lower than that of 0°stent (round straight stent), respectively. Except that the RS of C-shape linker stent was 1.48 N/mm, the RS of I, M, S and V-shape linker stents was not significantly different, which was 2.51, 2.61, 2.41, 2.52 N/mm, respectively, indicating that radial compression resistance of these four linker stents was almost the same. Conclusions Compared with traditional round straight stents, the RS of tapered stents will decrease, and the RS of stents will gradually decrease with the the taper increasing. Among all stent types in this study, except C-shape linker stents, the RS of other linker shapes has little effect on the RS of stents. The radial support performance of the stent can be improved by reducing the taper of the tapered stent, without changing the form of stent connecting ribs.

Clinical efficacy of simple taper retentive implants in immediate posterior dental implantation for 5-7 years / 华西口腔医学杂志

OBJECTIVES@#This study aimed to evaluate the long-term clinical efficacy of simple taper retentive implants in the posterior dental area after immediate implantation for 5-7 years.@*METHODS@#Selected from January 2015 to December 2017 in the Fourth Affiliated Hospital of Nanchang University dental clinic line tooth area immediately after the implant prosthesis, a total of 38 patients, 53 implants, were deep into (bone under 2 mm or higher) and the upper structure was repaired. In addition, after the completion of tracking observation of 60-90 months, the implant surrounding bone health was recorded and analyzed.@*RESULTS@#After 5-7 years of follow-up, 1 of the 53 implants failed to fall out, and the implant retention rate was 98.1%. The amount of bone resorption in the proximal and distal margins 5-7 years after implant restoration was (0.16±0.94) mm and (-0.01±1.29) mm, respectively, and the difference in bone height between the proximal and distal margins of the implant and the immediate post-restoration period was not statistically significant (P>0.05). No statistically significant differences were found in the effects of periodontitis, implant site inflammation, and smoking on peri-implant marginal bone resorption (P>0.05).@*CONCLUSIONS@#The single taper-retained implant broadens the indications for immediate implant placement in the posterior region, and its deep sub-osseous placement (≥2 mm below the bone) avoids to a certain extent the disturbance of the implant by external stimuli and the exposure of the cervical abutment of the implant, with the good long-term stability of the marginal bone around the implant.

Preparos endodônticos minimamente invasivos: construção de bases científicas / Minimally invasive endodontic prepararions: the construction of scientific bases

O conceito de Endodontia Minimamente Invasiva é amplo, e envolve não só a realização de acessos, mas também o uso de instrumentos com conicidades reduzidas ou geometrias inovadoras. Buscando avaliar se as estratégias minimamente invasivas adotadas apresentam vantagens frente aos tratamentos tradicionais, a presente tese foi dividida em três estudos. O estudo 1 avaliou a preservação da dentina perirradicular e o alargamento da porção apical dos canais de molares inferiores com instrumentos TruNatomy e ProTaper Gold. Para isso, vinte molares inferiores foram microtomografados, pareados e distribuídos em 2 grupos. No grupo ProTaper Gold, os canais mesial e distal foram preparados até os instrumentos F2 e F3, respectivamente, enquanto no grupo TruNatomy, os canais mesial e distal foram ampliados até os instrumentos prime e medium, respectivamente. Após um novo escaneamento, os parâmetros de instrumentação foram calculados. Os dados foram analisados pelos testes de Mann-Whitney, T Student e escalonamento multidimensional não-métrico. Não foram encontradas diferenças entre os grupos em relação à área não preparada e redução de espessura de dentina. O grupo ProTaper Gold removeu mais dentina que o TruNatomy no terço coronal das raízes mesiais. O estudo 2 avaliou a formação de microtrincas dentinárias em molares inferiores acessados de forma ultraconservadora (UltraAC), instrumentados com Reciproc e XP-Endo Shaper. Quarenta molares inferiores foram microtomografados, pareados e distribuídos em 4 grupos de acordo com o tipo de cavidade de acesso e protocolo do sistema de instrumentação: tradicional/Reciproc; tradicional/XP-endo Shaper; UltraAC/Reciproc e UltraAC/XP-endo Shaper. Após os preparos dos canais, os dentes foram escaneados novamente e as imagens transversais das raízes mesiais e distais, do nível da furca ao ápice foram avaliadas com o objetivo de identificar a presença de microtrincas dentinárias. Em todos os grupos, as microtrincas verificadas nas imagens pós-operatórias já estavam presentes no exame pré-operatório. O estudo 3 avaliou a influência de instrumentos com o mesmo diâmetro de ponta e diferentes conicidades no percentual de área não preparada e volume de dentina removida após o preparo dos canais mesiovestibular e distovestibular de molares superiores com ou sem o canal mesiovestibular 2 (MV2). Vinte e dois molares superiores foram selecionados, microtomografados, pareados e classificados em dois grupos, de acordo com a anatomia das raízes: dentes com MV2 e dentes sem MV2. Após o acesso, os canais radiculares foram preparados com instrumentos 25/.01, 25/.03, 25/.05, 25/.06 e 25/.08v. Os dentes foram submetidos a novos escaneamentos por micro-CT após preparo com cada instrumento descrito anteriormente. Os dados foram analisados usando o Modelo linear generalizado misto e aproximação de Kenward-Roger para testes Wald F. Em dentes com e sem canais MV2, a porcentagem de área não preparada apresentou uma diminuição significativa ao longo do tratamento após cada instrumento utilizado e a porcentagem de dentina removida apresentou um aumento significativo ao longo do tratamento. Com base nos estudos, concluiu-se que as estratégias minimamente invasivas adotadas não apresentaram vantagens frente aos tratamentos tradicionais(AU)

The concept of Minimally Invasive Endodontics is broad, and involves not only the realization of accesses, but also the use of instruments with reduced tapers or innovative geometries. Seeking to assess whether the minimally invasive strategies adopted have advantages over traditional treatments, this thesis was divided into three studies. Study 1 evaluated the preservation of periradicular dentin and enlargement of the apical portion of the mandibular molar canals prepared with TruNatomy and ProTaper Gold instruments. For this, twenty lower molars were microtomography, paired and divided into 2 groups. In the ProTaper Gold group, the mesial and distal canals were prepared up to the F2 and F3 instruments, respectively, while in the TruNatomy group, the mesial and distal canals were prepared up to the prime and medium instruments, respectively. After a new scan, the instrumentation parameters were calculated. Data were analyzed by Mann-Whitney, T Student and non-metric multidimensional scaling tests. No differences were found between groups regarding unprepared area and dentin thickness reduction. The ProTaper Gold group removed more dentin than TruNatomy in the coronal third of the mesial roots. Study 2 evaluated the formation of dentinal microcracks in mandibular molars accessed by ultraconservative cavites (UltraAC), instrumented with Reciproc and XP-Endo Shaper. Forty lower molars were microtomography, paired and divided into 4 groups according to the type of access cavity and instrumentation system protocol: traditional/Reciproc; traditional/XP-endo Shaper; UltraAC/Reciproc and UltraAC/XP-endo Shaper. After the root canal preparations, the teeth were scanned again and the transverse images of the mesial and distal roots, from the furcation level to the apex, were evaluated in order to identify the presence of dentinal microcracks. In all groups, the microcracks seen in the postoperative images were already present in the preoperative examination. Study 3 evaluated the influence of instruments with the same tip diameter and different tapers on the percentage of unprepared area and volume of dentin removed after preparation of the mesiobuccal and distobuccal canals of maxillary molars with or without the mesiobuccal canal 2 (MV2). Twenty-two maxillary molars were selected, microtomography, paired and classified into two groups, according to root anatomy: teeth with MV2 and teeth without MV2. After access, the root canals were prepared with instruments 25/.01, 25/.03, 25/.05, 25/.06 and 25/.08v. The teeth were rescanned by micro-CT after preparation with each instrument described above. Data were analyzed using the Generalized Linear Mixed Model and Kenward-Roger approximation for Wald F tests. In teeth with and without MV2 canals, the percentage of unprepared area showed a significant decrease throughout the treatment after each instrument used and the percentage of removed dentin showed a significant increase during treatment. Based on the studies, it was concluded that the minimally invasive strategies adopted did not present advantages over traditional treatments(AU)

Estratégias minimamente invasivas de acesso e preparo e os diferentes desfechos na terapia endodôntica / Minimally invasive access and root canal preparation strategies and the different outcomes in endodontic therapy

As cavidades de acesso dominaram a recente discussão sobre a Endodontia minimamente invasiva (EMI). No entanto, a rotulagem da EMI é mais ampla, envolvendo o uso de instrumentos com conicidades reduzidas ou geometrias inovadoras que permitam a remoção mínima de dentina. Além disso, aprimoramentos metodológicos têm sido sugeridos para mimetizar condições clínicas. Buscando responder algumas questões acerca da EMI, a presente tese é dividida em dois estudos. O estudo 1 avaliou a influência do acesso ultraconservador (UltraAC) na instrumentação, na qualidade da obturação e na capacidade máxima de carga para fratura em molares inferiores após o preparo do canal com o sistema XP-endo Shaper (XP) ou Reciproc (RC) em condições clínicas simuladas. Para isso, quarenta molares inferiores foram microtomografados e pareados em quatro grupos (n = 10), de acordo com o acesso e a instrumentação: TradAC/RC, TradAC/XP, UltraAC/RC e UltraAC/XP. Os dentes foram reescaneados e os parâmetros da instrumentação e obturação foram analisados. Os dentes foram restaurados e submetidos à ciclagem termomecânica e à capacidade máxima de carga para a fratura. O teste ANOVA foi usado para a análise estatística (P < 0,05). Os grupos TradAC apresentaram menor porcentagem (%) de área não preparada do que os grupos UltraAC (P < 0,05). O grupo UltraAC/XP apresentou a menor % de dentina removida (P < 0,05). A % de debris foi menor nos grupos UltraAC/XP e TradAC/XP do que no UltraAC/RC e TradAC/RC (P < 0,05). Os grupos UltraAC demonstraram maior % de espaços vazios e de material obturador na câmara pulpar (P < 0,05). Não houve diferença na capacidade máxima de carga para a fratura entre os grupos (P > 0,05). O estudo 2 avaliou o uso de instrumentos com conicidade reduzida - Bassi Logic ,03 (BL), com diferentes designs (XP) e como grupo de comparação o sistem Reciproc, na eficácia da instrumentação dos canais em condições clínicas simuladas. Vinte e quatro molares foram microtomografados, acessados de forma tradicional e divididos em três grupos (n = 8), de acordo com o preparo: BL, XP e RC. Nos grupos BL e RC, os canais mesiais foram instrumentados com 25/,03 ou R25 e o canal distal com 25/,03 e 40/,03 ou R25 e R40, respectivamente. No grupo XP, o mesmo instrumento foi utilizado em todos os canais (30/,04). Após o preparo, os dentes foram reescaneados e a % de área não preparada e de dentina removida foram avaliadas separadamente para os canais mesiais e distal. Os dados foram analisados com os testes ANOVA e de Tukey (P < 0,05). Verificou-se que o grupo BL apresentou maior % de área não preparada para ambos os canais em relação aos grupos XP e RC (P < 0,05). No entanto, não houve diferença na % de dentina removida entre os grupos (P > 0,05). Com base nos estudos, conclui-se que as estratégias minimamente invasivas adotadas no acesso e na instrumentação foram desvantajosas frente a tratamentos tradicionais, não justificando o seu uso(AU)

Access cavities have dominated the recent discussion on minimally invasive Endodontics (EMI). However, the issue of MIE is broader than access cavities, such as the use of instruments with reduced taper or innovative geometries that allow minimal dentin removal. Furthermore, methodological improvements have been suggested to mimic clinical conditions. Seeking to answer some questions about EMI, this thesis is divided into two studies. The first study evaluated the influence of ultraconservative access (UltraAC) on canal shaping, filling ability and maximum load capacity for fracture of mandibular molars after root canal preparation with XP-endo Shaper (XP) or Reciproc (RC), under simulated clinical conditions. Thus, forty mandibular molars were scanned and paired into four groups (n = 10), according to access and instrumentation protocol: TradAC/RC, TradAC/XP, UltraAC/RC and UltraAC/XP. Teeth were rescanned and the instrumentation and filling parameters were analyzed. The teeth were restored and submitted to thermomechanical cycling and maximum load capacity for the fracture. ANOVA test was used for statistical analysis (P < 0.05). The TradAC groups had a lower percentage (%) of unprepared area than the UltraAC groups (P < 0.05). The UltraAC/XP group had the lowest % of dentin removed (P < 0.05). The % of debris was lower in the UltraAC/XP and TradAC/XP groups than in the UltraAC/RC and TradAC/RC groups (P < 0.05). The highest % of voids and filling material in the pulp chamber was observed in the UltraAC groups (P < 0.05). There was no difference in the maximum load capacity for the fracture between the groups (P > 0.05). The second study evaluated the use of a reduced taper endodontic instrument system - Bassi Logic .03 taper (BL), expandable heat-treated system (XP) and, as comparison, the Reciproc system, on the ability to shape canals under simulated clinical conditions. For that, twenty-four mandibular molars were scanned and divided into three groups (n = 8), according to root canal instrumentation system: BL, XP and RC. In the BL and RC groups, the mesial canals were instrumented with 25/.03 or R25 and the distal canal with 25/.03 and 40/.03 or R25 and R40, respectively. In the XP group, the same instrument was used in all root canals (30/.04). After preparation, the teeth were rescanned and the % of unprepared area and dentin removed were evaluated separately for the mesial and distal canals. Data were analyzed using ANOVA and Tukey tests (P < 0.05). It was found that the BL group had a higher % of unprepared area for both root canals compared to the XP and RC groups (P < 0.05). However, there was no difference in the % of dentin removed between groups (P > 0.05). Based on the studies, it is concluded that there is no justification for the use of EMI since in general, UltraAC did not promote advantages over TradAC and the use of instruments with reduced taper resulted in a larger unprepared area, which could possibly influence the cleaning of the root canal system (AU)

Evaluación de la resistencia a la flexión de limas rotatorias Protaper Gold, 2Shape, V-Taper Fanta Gold / Evaluation of flexion resistance of Protaper Gold rotary limes, 2Shape, V-Tapert Fanta Gold

Antecedentes: Las limas rotatorias de níquel-titanio con tratamiento termomecánico se desarrollaron para permitir una mayor flexibilidad al instrumentar los conductos radiculares. Los instrumentos permitieron a los operadores tratar las curvaturas de los conductos con mayor facilidad. Los fabricantes están tratando de producir limas que funcionen de manera más eficiente y segura. Conocer las propiedades de las limas comercializadas es especialmente importante porque ayuda a elegir un sistema de lima apropiado. El objetivo de este estudio fue evaluar la flexibilidad de tres limas diferentes de níquel-titanio (NiTi) con tratamiento termomecánico en dos puntos diferentes. Materiales y métodos: Se midió la flexibilidad de tres limas NiTi con tratamiento termomecánico (ProTaper Gold, 2Shape y V-Taper Fanta Gold). Cada lima fue sujetada a 3 mm y 7 mm (n = 10/longitud/lima) y se utilizó una máquina de ensayo universal para doblarla a una fuerza máxima. Todos los datos fueron analizados estadísticamente por análisis de varianza de una vía y prueba de Tukey post hoc (p = 0,05) para determinar cualquier diferencia significativa. Resultados: Se halló diferencias estadísticamente significativas (p < 0,05). En general, V-Taper Fanta Gold fue la más rígida, ProTaper Gold mostró los mayores valores de fuerza y su deformación fue significativamente más flexible. Conclusión: Las limas ProTaper Gold mostraron una mayor flexibilidad en comparación con las otras limas estudiadas. (AU)

Background: Nickel-titanium rotary files with thermomechanical treatment were developed to allow greater flexibility when instrumenting the root canals. The instruments allowed operators to deal with duct curvatures more easily. Manufacturers are trying to produce files that work better efficiently and safely. Knowing the properties of marketed files is especially important in helping you choose an appropriate file system. The objective of this study was to evaluate the flexibility of three different nickel-titanium (NiTi) files with thermomechanical treatment at two different points along the file. Materials and methods: The flexibility of three NiTi files with thermomechanical treatment (Protaper Gold, 2Shape and V-Taper Fanta Gold) was measured. Each file was clamped at 3 mm and 7 mm (n = 10 / length / file) and a universal testing machine was used to bend the files to a maximum strength. All data were statistically analyzed by one-way analysis of variance and post-hoc Tukey test (P = 0.05) to determine any significant differences. Results: There were statistically significant differences (P <0.05). In general, V-Taper Fanta Gold was the most rigid, Protaper Gold showed the highest values of force and deformation was significantly more flexible. Conclusión: Protaper Gold files showed greater flexibility compared to the other files studied. (AU)

Evaluación radiográfica de la capacitación preclínica de alumnos de grado en el uso del sistema ProTaper Next en endodoncia / Radiographic evaluation of the preclinical training of undergraduate students in the use of ProTaper Next system in endodontics

Objetivo: Evaluar radiográficamente 162 tratamientos endodónticos realizados ex vivo en premolares inferiores y superiores humanos mediante el empleo del sistema ProTaper Next por parte de alumnos de grado de una cátedra de endodoncia de una universidad argentina. Materiales y métodos: Se evaluaron 162 tratamientos endodónticos realizados ex vivo durante los años 2017, 2018 y 2019 (54 por cohorte) en premolares inferiores y superiores humanos por alumnos de grado de la cátedra de Endodoncia I de la Escuela de Odontología de la Universidad del Salvador / Asociación Odontológica Argentina. Para la instrumentación fue empleado el sistema ProTaper Next. La muestra se tomó de forma aleatoria. En un programa de presentación de computadora se incluyeron las radiografías periapicales pre- y posoperatoria para su evaluación. Un evaluador externo analizó las imágenes radiográficas de los tratamientos y los categorizó como correctos o incorrectos teniendo en cuenta tres requisitos excluyentes: la conformación de la preparación quirúrgica, el límite apical y la homogeneidad de la obturación. Para el análisis estadístico, se utilizó la frecuencia relativa (intervalo de confianza 95%) y la prueba de chi-cuadrado. Resultados: La evaluación radiográfica de los tratamientos endodónticos realizados mostró un número considerable de tratamientos correctos. Los resultados para cada cohorte (años 2017, 2018 y 2019) fueron del 96,3% (87,2- 99,5%), el 94,4% (84,6-98,8%) y el 98,2% (90,1-99,9%) respectivamente. El porcentaje global de tratamientos correctos fue del 96,3% (92,1-98,6%). La diferencia entre las cohortes no fue estadísticamente significativa (P>0,05). Conclusión: El empleo del sistema ProTaper Next por parte de estudiantes de grado evaluados mostró resultados radiográficamente satisfactorios en la instrumentación ex vivo de conductos radiculares de premolares inferiores y superiores humanos (AU)

Aim: To evaluate radiographically, 162 endodontic treatments performed ex vivo by three cohorts of students from a school of dentistry in Argentina, using ProTaper Next rotatory system in mandibular and maxillary human premolars. Materials and methods: 162 mandibular and maxillary human premolars received endodontic treatment by undergraduate students from the Department of Endodontics I of the School of Dentistry USAL/AOA. The treatments were performed ex vivo during the academic years 2017, 2018 and 2019 (54 teeth were chosen for each cohort) using the rotatory system ProTaper Next. The samples were taken randomly. Pre and postoperative radiographs were included in a computer presentation program for its evaluation. An external examiner analysed the radiographic images by the shape of the preparation, the apical limit, and the homogeneity of the obturation, considering the treatments well obturated (correct) or ill obturated (incorrect). To be considered correct the case had to meet all the requirements. The statistic calculations used in this study were: relative frequency (confidence interval 95%) and the chi-square test. Results: The radiographic evaluation showed a considerable number of endodontic treatments correctly done using ProTaper Next system. The percentages for each cohort were 96.3% (87.2-99.5%), 94.4% (84.6-98.8%) y 98.2% (90.1-99.9%) for years 2017, 2018 y 2019 respectively. Global percentage of correctly endodontic treatments was 96.3% (92.1-98.6%). The difference between the cohorts was not statistically significant (P>0.05). Conclusion: The use of ProTaper Next by the dental students evaluated showed satisfactory results in the ex vivo instrumentation of mandibular and maxillary human premolar root canals (AU)

Corrosion at the head-neck taper as a cause for aspetic loosening after total arthroplasty / 医学研究生学报

Metal wear debris,as the most common one,may cause aspetic loosening after total hip arthroplasty.It is gradual-ly recognized that wear of head-neck taper may produce metal wear debris after the decline of application of metal on metal prothesis. Wear of head neck taper is mainly relevant to material quality and taper connection at the head neck junction.So we wrote this review to analyze the mechanical and cellular mechanisms of wear of head -neck taper,and furthermore summarize the clinical diagnosis,pre-vention and treatment on adverse local tissue reactions based on large quantities of reference.

Measurements of mechanical properties and morphology of root canal in maxillary primary anterior teeth / 华西口腔医学杂志

Objective This study aimed to measure the taper and diameter of root canal, as well as the elastic modulus and hardness in the root dentin of maxillary primary anterior teeth. Methods Patients under general anesthesia who needed root canal therapy in the maxillary primary anterior teeth were selected. Silicone impression material was used to take impressions. The impressions were scanned, and the taper and diameter of root canal were measured. Maxillary primary anterior teeth were collected in vitro. The elastic modulus and hardness of root dentin was tested. Results A total of 74 silicone impressions were obtained. The mean tapers of primary incisor teeth, primary lateral incisor teeth, and primary canine teeth were 0.106, 0.185, and 0.098, respectively. The mean diameters of the root canal 5 mm below the cementum-enamel junction (CEJ) were 1.267, 0.860, and 1.429 mm, respectively. The elastic modulus and hardness of root dentin were measured in 10 primary anterior teeth in vitro. The range of elastic modulus was 19.919-25.017 GPa. The range of hardness was 0.867-1.082 GPa. Conclusion The root canal post used in primary anterior teeth can be produced by the following data: taper of primary incisor teeth and primary canine teeth, 0.1; diameters of their tips, 1.2 mm and 1.4 mm, respectively; taper of primary lateral incisor teeth, 0.2; diameter of their tips, 0.8 mm; range of elastic modulus, 20-25 GPa; and range of hardness, 0.87-1.08 GPa.

Three-dimensional finite element analysis of different designs of residual posterior root restored with a new titanium alloy post / 口腔疾病防治

Objective @#To compare the stress distribution of residual posterior root restored with a new titanium alloy post of different diameter and taper, and discuss the rational design of posterior tooth post by the three-dimensional finite element method. @*Methods @#Mandibular second premolar image data was obtained by CBCT, and the mandibular second premolar post models with different diameter and taper were established with the help of Mimics data conversion, Geomagic Studio image processing technology and Creo/Parametric software. Then Abaqus was used to simulate the load condition of prosthesis and analyze the Von Mises stress of the cervical and apical regions.@*Results@#With the same diameter, the influence of the different post tapers on the peak stress of the root cervical area was irregular. When the taper was the same, the peak stress of the root apex area decreased firstly and then increased as the diameter increased. When the diameter was 1 mm, the peak stress of the root cervical and apex area was the lowest.@*Conclusion @#The effect of diameter on the stress distribution of dentin is more important than that of taper. To select the reasonable diameter and taper of the post is helpful to reduce the peak stress of the root cervical and apex area.

Features and advances of Morse taper connection in oral implant / 中华口腔医学杂志

Dental implants have been widely accepted as a predictable and reliable tool for dental reconstruction with the development of the economy. The design of implant-abutment connections has influence on mechanical properties and biological characteristics of implants. There are two types of implant-abutment connections, the external and the internal connections. Morse taper connection is one of the internal connections and its conical shape creates significant friction via the high propensity of parallelism between the two structures within the joint space. Several studies showed that Morse taper connection performed well in terms of survival rate, stability, bacterial seal and marginal bone loss. Recently, clinical studies indicate implants combining Morse taper connection with platform switching are helpful in reducing marginal bone absorption. This review aims at analyzing the features and advantages of Morse taper connection.

Reabilitação de maxila atrófica com implantes individualizados de conexão morse ­ quatro anos de acompanhamento / Rehabilitation of an edentulous atrophic maxillary arch using non-splinted morse cone dental implants ­ a 4-year case report

O objetivo deste trabalho foi demonstrar, através de um caso clínico, o passo a passo da reabilitação de maxila atrófica por meio de implantes individualizados de conexão cone-morse (OBL). Uma paciente do sexo feminino, com 62 anos de idade, apresentava uma relação maxilomandibular de Angle classe II, bastante perda óssea na maxila e falta de suporte ósseo para o tecido gengival, queixando-se de desconforto funcional e estético da prótese total superior convencional e com o anseio de ter todos os dentes de volta, da forma mais natural possível, através de implantes osseoin- tegráveis. A paciente foi submetida à reconstrução óssea com área doadora extraoral de crista ilíaca, com a finalidade de aumento na espessura óssea, o que levaria à maior oferta de tecido duro para instalação de implantes, além de melhor suporte para os tecidos moles. Quatro meses após a reconstrução, foram instalados 12 implantes individualizados cone-morse (OBL). Todos os implantes tiveram torque final acima de 45 Ncm e foram ancorados em tecido ósseo enxertado e remanescente. Com a reabertura dos implantes, foi confeccionada uma prótese fixa provisória. Neste momento, mais dois implantes foram colocados. Após seis meses de temporização, foram cimentadas as coroas individualizadas de cerâmica sobre os pilares personalizados cone-morse (OBL). O acompanhamento clínico de mais de quatro anos demonstrou que esta técnica de individualização de coroas sobre implantes se constitui em uma alternativa segura e, a cada dia, mais desejada pelos pacientes, uma vez que, na busca pela maior mimetização de uma arcada com dentes naturais, a possibilidade de ter coroas separadas os remete a um sorriso mais natural. Por outro lado, é preciso entender que vários são os aspectos a serem considerados antes de se optar por esta forma de reabilitação.

The objective of this study was to demonstrate, through a clinical case report, the step by step rehabilitation of an atrophic maxillary arch using non-splinted morse cone dental implants (OBL). First, a 62 years-old female patient presented with a class II Angle relationship, extensive bone loss and concomitant lack of support for the gingival tissue, also complaining of functional and esthetic discomfort due to her conventional dentures. Second, the patient stated her desire to "have all teeth back in their most natural way through dental implants". In this way, the patient was submitted to bone reconstruction using the iliac crest graft approach, to increase bone thickness, which would be enough supply for implant placement and better soft tissue support as well. Four months after the reconstruction surgery, 12 non-splinted Morse cone implants were installed (OBL). All implants had final insertion torque above 45 Ncm being anchored in grafted and native areas. After implant exposure, a provisional fixed prosthesis was delivered. At this point, two additional implants were placed. Six months individual ceramic crowns were cemented over customized morse cone abutments (OBL). The clinical follow-up now has more than four years and has showed that this technique constitutes a safe alternative and even more desired by patients since the seek for greater mimetics and the possibility to have single crowns lead to a more natural smile. On the other hand, it is necessary understand that there are several aspects to be considered before opting for rehabilitation protocol.

Implantes de diâmetro reduzido (< 3 mm) para reabilitação oral de espaços edêntulos atrésicos em pacientes adolescentes ­ relato de caso com acompanhamento de um ano / Reduced diameter dental implants (< 3 mm) for oral rehabilitation of edentulous atresic spaces

Reabilitações estéticas em áreas anteriores com limitação de espaço mesiodistal tornam-se um desafio. Entretanto, implantes dentários de diâmetros reduzidos (< 3 mm) têm sido utilizados nestes casos. Este relato de caso apresenta a utilização de dois implantes de diâmetro reduzido (2,8 mm) e conexão morse no tratamento de agenesia de laterais superiores. Após planejamento cirúrgico-protético, os implantes foram restaurados imediatamente e acompanhados por um período de um ano. Dentro das limitações deste trabalho, sugere-se que implantes de diâmetro reduzido podem ser utilizados com sucesso para a restauração imediata de laterais superiores, oferecendo um bom perfil de emergência protética e estética para dentes estreitos.

Esthetic rehabilitations in the anterior zones with limited mesiodistal spaces are a great challenge. However, dental implants with reduced diameters (< 3 mm) with a morse taper connection have been used in cases os lateral incisor agenesis. After a detailed surgical-prosthetic planning, the dental implants were immediately restored and followed-up for one year. Within the limits of this paper, it can be suggested that narrower dental implantes can be used with success in such situations, providing a good emergence profile and esthetics to for narrower dental spaces.

Microbiological Seal of Two Types of Tapered Implant Connections

Abstract Tapered implant connections have gained wide popularity for being more resistant to fatigue and for promoting a better seal against bacterial infiltration than conventional connections. The aim of this study was to evaluate the bacterial seal at the implant-abutment interface using two Morse taper implant models, by in vitro microbiological analysis. Eleven non-indexed and 11 indexed abutments were selected and connected to their respective implants with a 20 N torque, according to manufacturer's recommendation. Microbiological analysis was carried out using colonies of Escherichia coli transported directly from a culture dish to the prosthetic component. For control, one non-contaminated abutment-implant set from each group (negative control) and one contaminated implant with no abutment (positive control) were used. The specimens were immersed in BHI broth and maintained in an incubator at 37 °C for 14 days to assess the development of bacterial contamination. The results revealed that 36.4% (n=4) of the indexed components and 90.9% (n=10) of the non-indexed components allowed bacterial leakage, with significant difference between groups (p=0.0237). In conclusion, both tapered components failed to provide adequate sealing to bacterial leakage, although the indexed type components showed a superior seal compared with non-indexed components.

Resumo Conexões de implantes cônicos cresceram em popularidade por serem mais resistentes à fadiga e por promover uma melhor vedação contra infiltração bacteriana do que as conexões convencionais. O objetivo deste estudo foi avaliar o selamento bacteriano na interface implante-pilar utilizando dois modelos de implantes cone Morse, por meio de análise microbiológica in vitro. Onze pilares não indexados e 11 pilares indexados foram selecionados e conectados aos seus respectivos implantes com um torque de 20 N, de acordo com a recomendação do fabricante. A análise microbiológica foi realizada utilizando colônias de Escherichia coli retirados diretamente a partir de uma placa de cultura para o componente protético. Para os grupos de controle, foi utilizado um pilar-implante não contaminado de cada grupo (controle negativo) e um implante contaminado sem pilar (controle positivo). Os espécimes foram imersos em caldo BHI e mantidos numa incubadora a 37 °C durante 14 dias, para monitorar o desenvolvimento de contaminação bacteriana. Os resultados revelaram que 36,4% (n=4) dos componentes indexados e 90,9% (n=10) dos componentes não indexados obtiveram infiltração bacteriana, com diferença significativa entre os grupos (p=0,0237). Como conclusão, os dois componentes cônicos não conseguiram proporcionar uma vedação adequada contra infiltração bacteriana, embora os componentes do tipo indexados mostrassem uma vedação superior, quando comparados com componentes não indexados.

Uso racional de técnicas cirúrgicas implantares e periodontais para reabilitação na zona estética com coroas cerâmicas e metalocerâmicas / Rational use of periodontal and implant surgical techniques to rehabilitate the esthetic zone with all-ceramic and metalloceramic crowns ­ a case report

O objetivo deste trabalho foi relatar um caso clínico onde o planejamento reverso e o uso racional das cirurgias implantares e periodontais mostraram-se fundamentais no preparo para reabilitação da zona estética com coroas cerâmicas e metalocerâmicas. Uma paciente de 32 anos apresentava estética pobre, como ausências dentárias isoladas e perda de tecido mole/duro na região dos caninos superiores. O tratamento foi dividido em cinco etapas: 1) coroas provisórias e correção do plano oclusal e corredor bucal; 2) expansão da crista do rebordo e implantes conexão cone-morse/platform-switching (em dois estágios); 3) gengivoplastia; 4) reabertura e cirurgias gengivais (gengivectomia, enxerto ósseo/de tecido conjuntivo, divisão de papilas); e 5) condicionamento e colocação das coroas cerâmicas defi nitivas nos dentes (cimento resinoso) e metalocerâmicas (cimento fosfato de zinco) sobre os implantes. O desenvolvimento deste caso está baseado no uso da biomecânica de interface implante/pilar que confere os menores valores de reabsorção óssea ao longo do tempo, fornecendo restaurações definitivas com aspecto natural, e ainda apoiado por uma revisão sistemática demonstrando a eficácia do tecido conjuntivo subepitelial no aumento da largura queratinizada ao redor dos implantes. A finalização obtida é esteticamente aceitável e durável, muito desejável na região anterior da maxila.

The objective of this study was to report a case where the reverse planning and the rational use of implant and periodontal surgical protocols were fundamental to prepare the rehabilitation in the esthetic zone with all-ceramic and metalloceramic crowns. A 32 years-old patient had poor aesthetics, single-tooth defi cits, and soft/hard tissue losses in the region of the upper canines. After a concise planning, the treatment was divided into fi ve steps: 1) temporary crowns, correction of occlusal plane and buccal corridor; 2) ridge expansion, morse cone/platform-switching dental implants (two-stage procedure); 3) gingivoplasty; 4) implant exposure and gingival surgeries (gingivectomy, bone graft/connective tissue grafts, pedicle flaps); and 5) tissue conditioning and cementation of all-ceramic (resin cement) over teeth and metalloceramic (zinc phosphate cement) over the implant abutments. The development of this case is based on the use of a biomechanical implant interface/abutment which gives lower values of bone resorption over time, providing final restorations with a natural aspect, and still supported by a systematic review demonstrating the effectiveness of subepithelial connective tissue grafts to increase the width of the keratinized peri-implant mucosa. The outcome is esthetically acceptable and has long-term quality, a very desirable condition in the anterior maxilla.

Biomecânica da união dente-implante com plataforma restauradora reduzida, sistema de retenção tipo cone morse e roscas quadradas: uma análise por elementos finitos / Biomechanics of tooth-implant union with restorative platform reduced, restraint system morse cone type and square threads: a finite element analysis

Objetivou-se, a partir do Método dos Elementos Finitos, avaliar a biomecânica da união dente-implante e implante-implante, além de estabelecer uma análise qualitativa com achados fotoelásticos prévios. Foram planejados quatro modelos tridimensionais: dois Modelos Teste (dentes unidos a implantes) e dois Modelos Controle (a mesma condição, porém implanto suportada). Os implantes (ANKYLOS® - Dentsply) apresentaram conexão cônica, roscas quadradas e pilares Switching. Suas dimensões, ângulos externos e pilares protéticos foram obtidos a partir de um projetor de perfil. Já, dentes e próteses, a partir da visão direta, tiveram suas formas externas construídas em plataforma CAD (SOLIDSWORKS). O suporte alveolar foi configurado como um retângulo (68/30/15 mm). Todos os pilares foram posicionados no suporte alveolar, conforme os modelos físicos pré-existentes, gerando modelos sólidos. O ligamento periodontal consistiu de uma camada de 0,25 mm de espessura em poliéter (Impregum Soft, 3M Espe). Os modelos de dentes foram produzidos em dentina, pilares e implantes em titânio puro, próteses em liga Níquel-Cromo (Ni-Cr), e o suporte alveolar em resina fotoelástica (Araldite® - Produtos Químicos Ciba S/A do Brasil). As propriedades da resina foram obtidas por meio de ensaio de tração. Carga pontual, vertical e estática, de 150 N, foi aplicada. Os resultados destes ensaios evidenciaram menor concentração de tensão no aspecto cervical de implantes do grupo teste. Ao se confrontar tais achados com os fotoelásticos anteriormente obtidos, foi possível estabelecer uma relação direta entre as áreas mais solicitadas para os modelos de prótese fixa (PF) de três elementos. Concluiu-se que, para as condições estudadas ¿ conexão cônica, roscas quadradas e restauração com Plataforma Switching ¿, unir dentes a implantes parece ser uma terapia clínica viável, sugerindo, inclusive, ser mais favorável que a união de implantes entre si. Além disso, a partir da afinidade positiva entre os achados das duas técnicas, pôde-se considerar validados os modelos matemáticos de prótese fixa de três elementos

The goal of this study was to evaluate, from the Finite Element Method, the biomechanics of implant-tooth union and implant-implant and to establish a qualitative analysis with previous photoelastic findings. Four three-dimensional models were planned: two Test Models (teeth attached to implants) and two Control Models (the same condition, however implant supported). The implants (ANKYLOS® - Dentsply) showed conical connection, square threads and Switching pillars. Their dimensions, external angles and abutments were obtained from a profile projector. Already, teeth and dentures, from direct view, had their external forms built in CAD platform (SOLIDSWORKS). Alveolar support wasconfigured as a rectangle (68/30/15 mm). All the pillars were placed in the alveolar support, as the pre-existing physical models, generating solid models. The periodontal ligament consists of a layer of 0.25 mm thick in polyether (Impregum Soft, 3M Espe). The models of teeth trumped up of dentin, abutments and implants of pure titanium, prosthetics of Nickel-Chrome (Ni-Cr) alloy and alveolar support in photoelastic resin (Araldite® - Chemicals Ciba S/A of Brazil). The resin properties were obtained by traction tests. Punctual and vertical static load of 150 N was applied. The results of these tests showed lower concentration of tension in the cervical aspect of the test group implants. When comparing these findings with the photoelastic previously found, it was possible to establish a direct relation between the areas most requested for fixed prosthesis (FP) models of three elements. It was concluded that, for the studied conditions tapered connection, square threads and Platform Switching restoration , joining teeth implants seems to be a viable clinical therapy, suggesting, inclusive, to be more favorable than to join implants each other. Moreover, from the positive affinity between the findings of the two techniques, it was possible to consider validated the mathematical models of fixed prosthesis of three elements

Research progress and application of the aortic taper angle / 国际外科学杂志

Endovascular repair has gained worldwide popularity for the treatment of aortic dissection and aortic aneurysm.The non-tapered stents are selected usually.The aortic diameters vary in different level.High incidence of distal stent-induced complications is closely related to the aortic taper angle.According to several published studies,the aortic taper angle could be evaluated by establishing geometric model.Applications of tapered stents can significantly reducing the incidence of distal stent-induced comnplications.This review summaries the latest researches in the studies of the progress and the application of the aortic taper angle and the tapered stents,providing a reference for endovascular stent-graft selecting in the treatment of aortic dissection and aortic aneurysm.

Removal of gutta percha in root canal therapy with Pro Taper nickel titanium system / 局解手术学杂志

Objective To evaluate the results of different methods in removing the root canal gutta percha.Methods Select 60 man-dibular premolars with step-back techinique during root canal prepartion,and the mandibular premolars were stored for 2 weeks after AH-plus paste and gutta percha cold lateral condensation.And then they were randomly divided into 3 groups to remove the root canal filling.Group A were given manually cleaning and shaping with stainless steel instruments combined with chloroform.Group B were given Pro Taper nickel ti-tanium system.Group C were given Pro Taper nickel titanium system combined with microscopic ultrasound technology.The completion time of the 3 groups were recorded and the root canal wall cleanliness of the 3 groups were carefully observed.Results The competition time and amount of debris of apical foramen in group C were both significantly less than those of group A and group B,with statistically significant difference (P <0.05).And the cleanliness of root canal wall of group A was significantly better than that of group A and group B (P <0.05). Conclusion During the root canal retreatment,mechanically use Pro Taper nickel titanium system combined with microscopic ultrasound technology can improve the work efficiency and the cleanliness of root canal wall.

Periointegración / Periointegration

Se busca entender cuáles son las respuestas biológicas que se dan en diferentes etapas de la implantología, centrando la atención en la influencia de la tecnología en la formación del ancho biológico. Se analiza cómo fue evolucionando la ciencia en la búsqueda de mejores respuestas y cuáles serán los factores decisivos para que la tecnología influencie a la biología y poder aproximarse cada vez más a lo natural.

The aim of this paper is to understand the biological responses at the different stages of implantology, with a focus on the influence of technology in the formation of the biological width. It presents a study of the evolution of science towards better responses and the determining factors for technology to influence biology, which allow us to get closer to what is natural.

Compressive Resistance of Abutments with Different Diameters and Transmucosal Heights in Morse-Taper Implants

The aim of this study was to evaluate the compressive resistance under oblique loads of abutments with two different diameters and transmucosal heights used for cement-retained implant-supported prostheses in Morse-taper implants. Forty Morse-taper implants were divided into four groups with different abutment sizes for cement-retained prostheses in order to perform the compressive test. The groups were divided by abutment diameter and transmucosal height as follows: Group 1: 4.5 x 2.5 mm; Group 2: 4.5 x 3.5 mm; Group 3: 3.3 x 2.5 mm; and Group 4: 3.3 x 3.5 mm. An oblique compressive loading test was performed on each sample located in a platform at 30° using a universal testing machine with a load cell of 1,000 kgf and 0.5 mm/min speed until achieving the deformation of abutment's neck. The compressive resistance and its mechanical behavior were recorded for each group and the data were analyzed using ANOVA, the Shapiro-Wilk and Scheffé tests. In addition, the detailed damage of all samples was recorded with a conventional camera linked to the endoscopic equipment. Significant differences were observed among the groups, except between Groups 2 and 3 (p>0.005). All the abutments showed permanent deformations in the upper region and at the transmucosal portion, but the threads of the screws were intact. Fractures were only identified in Groups 3 and 4. Stronger mechanical behavior and compressive resistance was observed in the abutments with 4.5 mm diameter and 2.5 mm transmucosal height.

O objetivo deste estudo foi avaliar a resistência compressiva sob carga oblíqua em pilares com dois diferentes diâmetros e alturas de transmucoso usados para prótese implanto-suportada cimentada em implantes de cone Morse. Quarenta implantes de cone morse foram divididos em quatro grupos com diferentes tamanhos de pilares para próteses cimentadas a fim de realizar o teste compressivo. Os grupos foram divididos pelo diâmetro do pilar e altura de transmucoso como segue: 1) 4,5 x 2,5 mm; 2) 4,5 x 3,5 mm; 3) 3,3 x 2,5 mm; e 4) 3,3 x 3,5 mm. Um ensaio de compressão oblíqua foi realizado em cada amostra localizada numa plataforma a 30º utilizando uma máquina de ensaios universal, com célula de carga de 1.000 kgf e 0,5 mm/min de velocidade até atingir a deformação do pescoço do pilar. A resistência compressiva e seu comportamento mecânico foram registrados para cada grupo e os dados foram analisados utilizando os testes Shapiro-Wilk, ANOVA e Scheffé. Além disso, a deformação detalhada de todas as amostras foi registrada com uma câmera convencional conectada ao equipamento endoscópico. Foram observadas diferenças significativas entre os grupos, com exceção dos Grupos 2 e 3 (p>0,005). Todos os pilares mostraram deformação permanente na região superior e na porção transmucosa; porém, as roscas dos parafusos estavam intactas. Fraturas foram apenas identificadas nos Grupos 3 e 4. Foi observado melhor comportamento mecânico e resistência compressiva nos pilares com diâmetro de 4,5mm e altura de transmucoso de 2,5mm.