Sobrevivência em fadiga de coroas bioinspiradas bilaminadas: estudo in vitro / Fatigue survival rate of bioinspired bilaminar crowns: in vitro study

O objetivo deste estudo foi avaliar o comportamento biomecânico através da resistência à fadiga e análise por elementos finitos de coroas bioinspiradas bilaminadas com infraestruturas modificadas na superfície vestibular (Estudo A) e utilizando diferentes materiais cerâmicos com módulos elásticos distintos (Estudo B). Para isso, foram confeccionados 90 preparos para coroa total em resina epóxi G10, sobre os quais foram preparadas coroas bioinspiradas de acordo com os seguintes grupos: Estudo A - IC (infraestrutura convencional), IME (infraestrutura modificada estratificada) e IMC (infraestrutura modificada cimentada), todas confeccionadas em dissilicato de lítio (infraestrutura) + porcelana (recobrimento); Estudo B ­ DL+LEU (dissilicato de lítio + leucita), LEU+DL (leucita + dissilicato de lítio), CH+DL (cerâmica híbrida + dissilicato de lítio) e CH+LEU (cerâmica híbrida + leucita). Para o Estudo A, todas as infraestruturas foram usinadas; os recobrimentos dos grupos IC e IME foram confeccionados através da estratificação, e os recobrimentos do grupo IMC foram usinados. Já para o Estudo B, todas as peças foram usinadas, de acordo com o material cerâmico de cada grupo. Em seguida, foi realizada a cimentação adesiva dos recobrimentos sobre as infraestruturas (a depender do grupo) e das coroas sobre os preparos utilizando cimento resinoso fotopolimerizável (Variolink Esthetic LC). Após a cimentação, os espécimes foram submetidos ao teste de fadiga cíclica (10.000 ciclos, 20Hz), e como desfecho foram considerados dois eventos, em que o primeiro foi a ocorrência de trinca e/ou lascamento (evento 1) e o segundo foi a falha catastrófica do conjunto (evento 2). Os valores de carga e número de ciclos para falha em que foram observados os eventos 1 e 2 foram utilizados para realizar a análise de sobrevivência de acordo com Kaplan-Meier e Log-Rank (Mantel-Cox; 95%). As marcas de fratura e o modo de falha das coroas foram avaliados e classificados por estereomicroscópio óptico e microscópio eletrônico de varredura. Por fim, foi realizada análise por elementos finitos (FEA) para ambos os estudos, a fim de avaliar a distribuição de tensões sobre as coroas e interface adesiva. Para o Estudo A, os resultados do teste de fadiga mostraram que, considerando o evento 1 (trinca/lascamento), os grupos IC e IMC apresentaram médias de carga fadiga estatisticamente significantes entre si (733,33 N e 913,33 N, respectivamente), enquanto o grupo IME apresentou média superior (1.020 N). O mesmo foi observado para o número de ciclos em fadiga para todos os grupos. Ao considerar o evento 2 (falha catastrófica), os três grupos apresentaram médias estatisticamente semelhantes entre si (~1.028 N). Os resultados de FEA mostraram que o grupo IC concentrou maior tensão de tração do que os grupos IME e IMC. Para o Estudo B, no teste de fadiga, o grupo DL+LEU apresentou a maior média de resistência à fadiga (evento 1: 913,33 N e evento 2: 1033,33 N), enquanto todas as outras combinações de materiais cerâmicos analisadas foram estatisticamente semelhantes entre si, considerando carga e número de ciclos. Com relação ao FEA, os grupos com cerâmica híbrida (CH+DL e CH+LEU) apresentaram menores picos de concentração de tensão na infraestrutura do que os grupos com cerâmicas vítreas (DL+LEU e LEU+DL), porém, em contrapartida, concentraram maior tensão na interface adesiva. Com isso, conclui-se que a utilização da infraestrutura modificada é uma alternativa viável e promissora para tratamentos reabilitadores, apresentando sobrevivência em fadiga e distribuição de tensões satisfatórias. Além disso, a combinação entre uma infraestrutura de dissilicato de lítio e recobrimento de cerâmica a base de leucita corresponde a melhor abordagem considerando a infraestrutura modificada.(AU)

The objective of this study was to evaluate the biomechanical behavior through fatigue resistance and finite element analysis of bilaminar bioinspired crowns with modified infrastructures on the buccal surface (Study A) and using different ceramic materials with different elastic moduli (Study B). For this, 90 preparations were made for a full crown in G10 epoxy resin, on which bioinspired crowns were prepared according to the following groups: Study A - CI (conventional infrastructure), SMI (stratified modified infrastructure) and CMI (cemented modified infrastructure ), all made of lithium disilicate (infrastructure) + porcelain (veneer); Study B ­ LD+LEU (lithium disilicate + leucite), LEU+LD (leucite + lithium disilicate), HC+LD (hybrid ceramic + lithium disilicate) and HC+LEU (hybrid ceramic + leucite). For Study A, all infrastructures were machined; the coverings of the CI and SMI groups were made through stratification technique, and the veneers of the SMI group were machined. For Study B, all pieces were machined, according to the ceramic material of each group. Then, the veneers were cemented into their infrastructures (depending on the group) and crowns were cemented into preparations using light-cured resin cement (Variolink Esthetic LC). After cementing, the specimens were subjected to the cyclic fatigue test (10,000 cycles, 20Hz), and as an outcome two events were considered: the occurrence of cracking and/or chipping (event 1) and catastrophic failure (event 2). The load (N) and number of cycles to failure in which events 1 and 2 were observed were used to perform the survival analysis according to Kaplan-Meier and Log-Rank (Mantel- Cox; 95%). The fracture marks and failure mode of the crowns were evaluated and classified by optical stereomicroscope and scanning electron microscope. Finally, finite element analysis (FEA) was performed for both studies in order to evaluate the stress distribution over the crowns and adhesive interface. For Study A, the results of the fatigue test showed that, considering event 1 (cracking/chipping), the CI and CMI groups presented average to failure that were statistically significant compared to each other (733.33 N and 913.33 N, respectively), while the SMI group showed higher averages (1,020 N). Same pattern was observed for the number of cycles under fatigue for both groups. When considering event 2 (catastrophic failure), the three groups presented statistically similar means (~1,028 N). The FEA results showed that the CI group concentrated greater tensile stress than the CMI and SMI groups. For Study B, in the fatigue test, the LC+LEU group presented the highest average fatigue resistance (event 1: 913.33 N and event 2: 1033.33 N), while all other combinations of ceramic materials analyzed were statistically similar to each other, considering load and number of cycles. Regarding FEA, the groups with hybrid ceramics (HC+LC and HC+LEU) showed lower stress concentration peaks in the infrastructure than the groups with glass ceramics (LC+LEU and LEU+LC), however, on the other hand, concentrated greater tension at the adhesive interface. With this, it is concluded that the use of modified infrastructure is a viable and promising alternative for oral rehabilitation treatments, presenting satisfactory fatigue survival and adequate stress distribution. Furthermore, the combination of a lithium disilicate infrastructure and a leucite-based ceramic coating corresponds to the best approach considering the modified infrastructure.(AU)

Caso Clínico: Reabilitação Cerâmica Anterior com Sistema CAD/CAM / Anterior Rehabilitation with CAD/CAM System: Case Report

Devido a constante busca por um sorriso harmônico, o nível de exigência e a expectativa dos pacientes tornam-se elevados, propiciando o desenvolvimento de novos materiais e técnicas odontológicas que visam procedimentos mais conservadores e resultados cada vez mais previsíveis esteticamente. As técnicas com Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) têm ocupado lugar de destaque na Odontologia. Isso se deve ao fato de que o projeto auxiliado por computador ou fabricação assistida por computador oferece um método de restauração que diminui o risco de erro humano e fornece resultados altamente estéticos em um tempo clínico reduzido, embora com custos relativamente altos. O objetivo do presente estudo é apresentar, através de um relato de caso clínico, uma reabilitação estética por meio da aplicação prática do sistema CAD / CAM. Com a finalização do caso foi possível observar melhora estética através da confecção das coroas cerâmicas anteriores e melhora da condição oclusal com a confecção de prótese removível superior, a qual viabiliza uma maior durabilidade das coroas cerâmicas, pois distribui melhor as cargas oclusais entre os elementos, evitando cargas excessivas no local das novas restaurações indiretas. Este relato de caso foi realizado em duas sessões odontológicas alcançando satisfação estética da paciente. Possui um acompanhamento de curto prazo, portanto, são necessários casos com acompanhamento a longo prazo para comprovar o sucesso dessa técnica. Pode-se considerar uma limitação o elevado custo tecnológico, porém é notório avanço na odontologia para melhorar a qualidade no tratamento em períodos extremamente curtos.

Due to the constant search for a harmonic smile, the level of demand and the expectations of patients become high, enabling the development of new materials and dental techniques that aim at more conservative procedures and more and more predictable results aesthetically. Techniques with Computer Aided Design and Computer Aided Manufacturing (CAD / CAM) have occupied a prominent place in Dentistry. This is due to the fact that computer aided design or computer aided manufacturing offers a restoration method that lowers the risk of human error and provides highly aesthetic results in a reduced clinical time, albeit at relatively high costs. The objective of the present study is to present, through a clinical case report, an aesthetic rehabilitation through the practical application of the CAD / CAM system. With the completion of the case, it was possible to observe aesthetic improvement through the preparation of the anterior ceramic crowns and improvement of the occlusal condition with the manufacture of a removable upper prosthesis, which enables greater durability of the ceramic crowns, as it better distributes the occlusal loads among the elements, avoiding excessive loads at the site of new indirect restorations. This case report was carried out in two dental sessions, achieving patient aesthetic satisfaction. It has a short-term follow-up, therefore, cases with long-term follow- up are necessary to prove the success of this technique. The high technological cost can be considered a limitation, but there is a notable advance in Dentistry to improve the quality of treatment in extremely short periods.

Ángulos de convergencia en preparaciones dentarias realizadas en tipodontos por estudiantes de Odontología, Unach / Convergence angles in dental preparations performed on typodont by students of dentistry, UNACH

El objetivo de esta investigación fue analizar los ángulos de convergencia en preparaciones dentarias para coronas realizadas en tipodontos, por estudiantes de décimo semestre de Odontología Unach. Las preparaciones dentales para coronas poseen características de retención y resistencia, principios fundamentales que ofrecen éxito y longevidad de la corona definitiva. Varios investigadores a nivel mundial han desarrollado diversos métodos para evaluar los ángulos de convergencia de las preparaciones extracoronarias; sin embargo, en nuestro medio, no existen estudios acerca de la medición de estos ángulos. Esta investigación fue de carácter experimental, transversal y observacional, se obtuvieron 32 preparaciones dentarias para coronas de recubrimiento completo, cada estudiante tuvo 60 minutos para tallar dos preparaciones dentarias en simuladores clínicos. Los tipodontos fueron escaneados y digitalizados mediante el escáner CAD-CAM Ceramill Database versión 1.0 año 2010 del Laboratorio "BrothersDent" para producir imágenes tridimensionales. El software iTero midió los ángulos vestíbulo-lingual (VL) y mesio-distal (MD) de cada preparación. Los ángulos más pequeño y más grande observados fueron 3.1° y 102.5° para molares mandibulares. El promedio del ángulo VL para dientes anteriores fue 40,38 ±4,38° en varones y 36,97 ±3,95° en mujeres y el promedio del ángulo MD fue 44,68 ±5,51° en varones y 40,08 ±3,99° en mujeres. Para dientes posteriores el promedio VL fue 27,46 ±7,82° en varones y 40,98 ±4,63° en mujeres; y el promedio del ángulo MD fue 40,73 ±5,95° en varones y 50,62 ±7,00° en mujeres. En conclusión, los ángulos de convergencia logrados por estudiantes fueron mayores que los ideales recomendados según Shillingburg.

This research aimed to analyze the angles of convergence in dental preparations for crowns performed on typodont, by 10th semester students of school of dentistry, UNACH. Dental preparations for crowns have retention and resistance characteristics, fundamental principles that offer success and longevity of the final crown. Various researchers worldwide have developed various methods to evaluate the convergence angles of extra coronary preparations; however, in our context, there are no studies on the measurement of these angles. This research was experimental, cross-sectional and observational, 32 dental preparations were obtained for fully covered crowns, each student had 60 minutes to carve two dental preparations in clinical simulators. The typodonts were scanned and digitized using the scanner CAD-CAM Ceramill Database version 1.0 - 2010 of "BrothersDent" Laboratory in order to produce three-dimensional images. The iTero software measured the vestibule-lingual (VL) and mesio-distal (MD) angles of each preparation. The smallest and largest angles observed were 3.1 ° and 102.5 ° for mandibular molars. The mean VL angle for anterior teeth was 40.38 ± 4.38 ° in males and 36.97 ± 3.95 ° in females, and the mean MD angle was 44.68 ± 5.51 ° in males and 40, 08 ± 3.99 ° in women. For posterior teeth the average VL was 27.46 ± 7.82 ° in men and 40.98 ± 4.63 ° in women; and the mean MD angle was 40.73 ± 5.95 ° in men and 50.62 ± 7.00 ° in women. In conclusion, the convergence angles achieved by students were greater than the recommended ideals according to Shillingburg.

Comparison of Conventional and Pontic Fixed Partial Dentures Over Implants Using the Finite Element Method: Three-Dimensional Analysis of Cortical and Medullary Bone Stress.

Rehabilitation with implant prostheses in posterior areas requires the maximum number of possible implants due to the greater masticatory load of the region. However, the necessary minimum requirements are not always present in full. This project analyzed the minimum principal stresses (TMiP, representative of the compressive stress) to the friable structures, specifically the vestibular face of the cortical bone and the vestibular and internal/lingual face of the medullary bone. The experimental groups were as follows: the regular splinted group (GR), with a conventional infrastructure on 3 regular-length Morse taper implants (4 × 11 mm); and the regular pontic group (GP), with a pontic infrastructure on 2 regular-length Morse taper implants (4 × 11 mm). The results showed that the TMiP of the cortical and medullary bones were greater for the GP in regions surrounding the implants (especially in the cervical and apical areas of the same region) but they did not reach bone damage levels, at least under the loads applied in this study. It was concluded that greater stress observed in the GP demonstrates greater fragility with this modality of rehabilitation; this should draw the professional's attention to possible biomechanical implications. Whenever possible, professionals should give preference to use of a greater number of implants in the rehabilitation system, with a focus on preserving the supporting tissue with the generation of less intense stresses.

Surgical and nonsurgical treatment of papillary hyperplasia: A case report / Tratamiento quirúrgico y no quirúrgico de la hiperplasia papilar inflamatoria: Reporte de Caso

Dentures with dental plaque predispose recurrent hyperplasia on the palatal mucosa. Surgical procedures for the treatment of inflammatory papillary hyperplasia involve postsurgical discomfort and morbidity. This repot describes clinical and histologic aspects of a patient with severe akantolitic inflammatory papillary hyperplasia. The palatal mucosa was treated with a surgical bur with a low-speed handpiece. A new removable denture was performed and adapted. A follow-up of 4 years showed staility of health at palatal mucosa. Patient referred low discomfort and morbidity when using bur technique. Control of removable denture was critical for long-term healing and soft tissue stability.

Las prótesis dentales con placa bacteriana predisponen a la hiperplasia recurrente en la mucosa palatina. Los procedimientos quirúrgicos para el tratamiento de la hiperplasia papilar inflamatoria implican molestias y morbilidad posquirúrgicas. Este reporte describe los aspectos clínicos e histológicos de un paciente con hiperplasia papilar inflamatoria acantolítica severa. La mucosa palatina fue tratada con una fresa quirúrgica con una pieza de mano de baja velocidad. Se realizó y adaptó una nueva prótesis parcial removible. Después de un seguimiento de 4 años, se encontró estabilidad de la salud de la mucosa palatina. El paciente se refirió a la baja incomodidad y morbilidad al usar la técnica de la fresa. El control de la prótesis parcial removible fue crítico para la cicatrización a largo plazo y la estabilidad de los tejidos blandos, evitando la recidiva de la hiperplasia papilar inflamatoria.

[Application of polyetheretherketone and its composite as frameworks in fixed dental prostheses].

Characterized by eminent mechanical properties, chemical stability and biosafety, polyetheretherketone (PEEK), as a brand-new type of biomedical material, has been applied in the field of stomatology. This review elaborates on basic behaviors and fabrication methods of PEEK and its composite, and their application in fixed dental prostheses (FDP) as frameworks as well as their adhesive properties. Meanwhile, this review also looks into the prospect of the integration of additive manufacturing in fabricating frameworks of PEEK and its composite in FDP.

[Three-dimensional finite element analysis of cantilever fixed bridge supported by implants with mandibular central incisor].

Objective: To investigate effect of the contact surface between the bridge and the adjacent teeth on the stress distribution of the implant and bone tissue and the displacement of the prosthesis in the cantilever fixed implant bridge restoring missing mandibular central incisors. Methods: Two-dimensional images of the mandible and dentition in healthy adults were obtained using CT data. A three-dimensional finite element model of cantilever fixed bridge supported by implants with mandibular central incisor was established by computer reconstruction technique.The contact surface between the bridge and the adjacent natural tooth was designed as "oval" and "trapezoid". The "trapezoid" has a slightly smaller median diameter on the labial side and a slightly larger medial diameter on the lingual side. Loading of 120 N was applied on the tangential margin of the middle line of the long axis of the bridge 41. The direction was set at 0°, which was parallel to the long axis of the tooth and downward. The buccal to lingual and downward angles were 30°, 45° and 60°, respectively, perpendicular to the long axis of the tooth and 90° to the lingual side.The stress distribution of the implant and surrounding bone tissue and the displacement of the prosthesis were compared between the two models. Results: Under axial and buccolingual loading, the maximum equivalent stress peak in the implant and surrounding bone tissue in the cantilever with trapezoidal contact surface design and the maximum displacement of the prosthesis were lower. Moreover, the distribution of stress was more balanced and the concentration range of stress was smaller. With the loading angle increasing, this trend was more obvious. When loading angle increased to 90°, the maximum equivalent stress and the maximum displacement of the elliptic contact surface model implant and surrounding bone tissue were 196 and 101 MPa and 0.196 mm, respectively, while the trapezoidal contact surface model were 157 and 72 MPa and 0.164 mm, respectively. Conclusions: The trapezoidal contact surface of the bridge and the adjacent teeth in the cantilever fixed bridge supported by implants with mandibular central incisor is beneficial to reduce the impact of the leverage on the implant and surrounding bone tissue.

[Comparison of flow conditions of adhesives and retention force of restorations among four cement-retained methods of implant-supported fixed prostheses].

Objective: To compare the effect on the flow conditions of adhesives and the retention force of restorations among different cement-retained methods of implant-supported fixed prostheses. Methods: Four common cement-retained methods were selected, including the occlusal hole for screw access (OH), the lingual hole for adhesives overflow (LH), the resin replica for titanium abutment (RR), and the traditional cement-retained method (the control group). The adhesive used in this study was resin-modified glass ionomer cement. The two-dimensional analysis models of computational fluid dynamics (CFD) were established. The flow conditions of adhesives in the adhesion process was analyzed by the CFD analysis. The internal filling ratio and the amount of neck overflow of adhesives below the edge of the prosthesis were calculated. Ten zirconia prostheses in each group were processed and cemented. The retention force was examined by mechanical tensile experiments in vitro. Results: The CFD analysis showed the internal filling ratio of adhesives from high to low was the LH group, the OH group, the RR group and the control group. The amount of neck overflow of adhesives below the edge of the prosthesis from less to more was the RR group, the OH group, the LH group and the control group. The retention force was (240.7±33.9) N in the control group, (278.2±59.1) N in the OH group, (292.9±47.9) N in the LH group, and (262.8±59.4) N in the RR group. There was a statistically significant difference in the retention force between the LH group and the control group (P=0.029). There was no significant difference among the other groups (P>0.05). Conclusions: The modified cement-retained methods can effectively reduce the amount of neck overflow of adhesives, and improve the filling condition of adhesive in the adhesive clearance to ensure the retention force of the prostheses. Clinically, the appropriate modified cement-retained method should be selected according to the three-dimensional position of the implant and the position of prosthetic margin.

Comparison of flow conditions of adhesives and retention force of restorations among four cement-retained methods of implant-supported fixed prostheses / 中华口腔医学杂志

Objective@#To compare the effect on the flow conditions of adhesives and the retention force of restorations among different cement-retained methods of implant-supported fixed prostheses.@*Methods@#Four common cement-retained methods were selected, including the occlusal hole for screw access (OH), the lingual hole for adhesives overflow (LH), the resin replica for titanium abutment (RR), and the traditional cement-retained method (the control group). The adhesive used in this study was resin-modified glass ionomer cement. The two-dimensional analysis models of computational fluid dynamics (CFD) were established. The flow conditions of adhesives in the adhesion process was analyzed by the CFD analysis. The internal filling ratio and the amount of neck overflow of adhesives below the edge of the prosthesis were calculated. Ten zirconia prostheses in each group were processed and cemented. The retention force was examined by mechanical tensile experiments in vitro.@*Results@#The CFD analysis showed the internal filling ratio of adhesives from high to low was the LH group, the OH group, the RR group and the control group. The amount of neck overflow of adhesives below the edge of the prosthesis from less to more was the RR group, the OH group, the LH group and the control group. The retention force was (240.7±33.9) N in the control group, (278.2±59.1) N in the OH group, (292.9±47.9) N in the LH group, and (262.8±59.4) N in the RR group. There was a statistically significant difference in the retention force between the LH group and the control group (P=0.029). There was no significant difference among the other groups (P>0.05).@*Conclusions@#The modified cement-retained methods can effectively reduce the amount of neck overflow of adhesives, and improve the filling condition of adhesive in the adhesive clearance to ensure the retention force of the prostheses. Clinically, the appropriate modified cement-retained method should be selected according to the three-dimensional position of the implant and the position of prosthetic margin.

Three-dimensional finite element analysis of cantilever fixed bridge supported by implants with mandibular central incisor / 中华口腔医学杂志

Objective@#To investigate effect of the contact surface between the bridge and the adjacent teeth on the stress distribution of the implant and bone tissue and the displacement of the prosthesis in the cantilever fixed implant bridge restoring missing mandibular central incisors.@*Methods@#Two-dimensional images of the mandible and dentition in healthy adults were obtained using CT data. A three-dimensional finite element model of cantilever fixed bridge supported by implants with mandibular central incisor was established by computer reconstruction technique.The contact surface between the bridge and the adjacent natural tooth was designed as "oval" and "trapezoid". The "trapezoid" has a slightly smaller median diameter on the labial side and a slightly larger medial diameter on the lingual side. Loading of 120 N was applied on the tangential margin of the middle line of the long axis of the bridge 41. The direction was set at 0°, which was parallel to the long axis of the tooth and downward. The buccal to lingual and downward angles were 30°, 45° and 60°, respectively, perpendicular to the long axis of the tooth and 90° to the lingual side.The stress distribution of the implant and surrounding bone tissue and the displacement of the prosthesis were compared between the two models.@*Results@#Under axial and buccolingual loading, the maximum equivalent stress peak in the implant and surrounding bone tissue in the cantilever with trapezoidal contact surface design and the maximum displacement of the prosthesis were lower. Moreover, the distribution of stress was more balanced and the concentration range of stress was smaller. With the loading angle increasing, this trend was more obvious. When loading angle increased to 90°, the maximum equivalent stress and the maximum displacement of the elliptic contact surface model implant and surrounding bone tissue were 196 and 101 MPa and 0.196 mm, respectively, while the trapezoidal contact surface model were 157 and 72 MPa and 0.164 mm, respectively.@*Conclusions@#The trapezoidal contact surface of the bridge and the adjacent teeth in the cantilever fixed bridge supported by implants with mandibular central incisor is beneficial to reduce the impact of the leverage on the implant and surrounding bone tissue.

Application of polyetheretherketone and its composite as frameworks in fixed dental prostheses / 中华口腔医学杂志

Characterized by eminent mechanical properties, chemical stability and biosafety, polyetheretherketone (PEEK), as a brand-new type of biomedical material, has been applied in the field of stomatology. This review elaborates on basic behaviors and fabrication methods of PEEK and its composite, and their application in fixed dental prostheses (FDP) as frameworks as well as their adhesive properties. Meanwhile, this review also looks into the prospect of the integration of additive manufacturing in fabricating frameworks of PEEK and its composite in FDP.

Evaluation of Marginal and Internal Integrity of Modified Resin-Bonded Fixed Partial Dentures: An In Vitro Study

PURPOSE: The purpose of this study was to evaluate the microleakage of various types of resin-bonded fixed partial dentures (RBFPDs) after artificial aging. MATERIALS AND METHODS: Forty models with missing first molar were fabricated using artificial resin teeth and were divided into four groups: Group A, conventional RBFPDs design; Group B, modified RBFPDs design; Group C, assembled 3-piece RBFPDs design; and Group D, assembled 3-piece RBFPDs with different occlusal rest positions. Half of the specimens underwent chewing simulation process (240,000 cycles, 50 N load, 1.7 Hz) and thermocycling (temperatures 5℃~55℃, dwelling time 30 seconds) and the remaining 20 specimens didn't receive any treatment. All the specimens were immersed in 2% methylene blue solution for 24 hours to evaluate microleakage, and were sectioned at the middle part of abutment teeth. To evaluate the microleaskage, a dye penetration was calculated. RESULT: With artificial aging, cyclic loading and thermocycling, a 3-piece RBPFD and a 2-piece RBPFD using original tooth undercuts have significantly lower microleakge (P<0.05) compared to the conventional design of RBPFD and modified RBPFD. CONCLUSION: Within the limit of this experiment, the assembled RBFPDs exhibited a smaller microleakage than the conventional RBFPDs, implying that the assembled RBFPDs can be more effective for reducing the dislodgement of the RBFPDs.

Rehabilitación estética y funcional con una prótesis parcial fija en la dentición primaria: reporte de caso / Aesthetic and functional rehabilitation with a fixed prosthetic denture in the primary dentition: A case report / Aesthetic and functional rehabilitation with a fixed prosthetic denture in the primary dentition: A case report

La caries de infancia temprana (CIT) es una enfermedad de etiología multifactorial que afecta al ser humano en fase prees-colar, en un nivel más agresivo se presenta como caries severa en la infancia (CSI) y tiene inicio en los incisivos primarios superiores. Paciente, 4 años de edad de sexo femenino, al examen clínico presenta múltiples lesiones de caries, con diag-nóstico de necrosis pulpar y fístulas en los incisivos centrales superiores primarios que fueron extraídos, lesiones de caries en los incisivos laterales superiores sin compromiso pulpar que fueron utilizados como pilares para la prótesis, el tratamien-to indicado fue la construcción y cementación de una prótesis fija de sistema tubo-barra, llamada prótesis Denari, creada por el Dr. Walter Denari (UNISANTA- Brasil), la cual presenta como características principales: permite el crecimiento transversal del maxilar superior, es fijo con el objetivo de evitar pérdidas por parte del niño, recupera la función y la sonrisa perdida. Se realiza un desgaste mínimo de los pilares dentales y es una alternativa de tratamiento que evita alteraciones en el habla, degluciones atípicas y restablece la armonía de la sonrisa de forma simple y eficiente en el paciente.

Early Childhood Caries (ECC) is a disease of multifactorial etiology that affects the human being in the preschool stage, in a more aggressive level presents as severe caries in childhood (S-ECC) and has onset in the upper primary incisors. Patient, 4 years old female, on clinical examination presented multiple caries lesions, with diagnosis of pulp necrosis and fistulas in the primary upper incisors that were extracted, caries lesions on the upper lateral incisors without pulp involvement that were used as the pillars for the prosthesis, the treatment indicated was the construction and cementation of a fixed prosthe-sis of a tube-bar system, called Denari prosthesis, created by Dr. Walter Denari (UNISANTA- Brasil), which presents as main characteristics: Transversal growth of the upper jaw, it is fixed with the aim of avoiding losses on the part of the child, regain function and smile lost. It's a minimal wear of dental pillars and is an alternative treatment that avoids alterations in speech, atypical swallows and restores the harmony of simple and efficient smile way in the patient.

Cárie precoce na infância (CPI) é uma doença de etiologia multifatorial que afeta os seres humanos em fase pré-escolar, um nível mais agressivo é apresentado como Cárie Severa na infância (CSI) e tem início nos incisivos primários superiores. Paciente, do sexo feminino de 4 anos de idade, ao exame clínico apresenta múltiplas lesões de cárie, com diagnóstico de ne-crose pulpar e fístulas nos incisivos centrais superiores primários que foram extraídos, lesões de cárie nos incisivos laterais superiores sem envolvimento pulpar que foram utilizados como pilares protéticos, o tratamento indicado foi a construção e cimentação de uma prótese fixa de sistema tubo-barra, chamada próteses Denari, criado pelo Dr. Walter Denari (UNISAN-TA- Brasil), o qual apresenta as seguintes características principais: permite crescimento transversal da maxila, é fixo com o objetivo de evitar perdas pela criança, recupera a função e o sorriso perdido. Realiza-se um desgaste mínimo dos pilares dentários e é um tratamento alternativo que evita alterações na fala, deglutição atípica e restabelece a harmonia do sorriso de forma simples e eficiente no paciente.

Immediate fixed partial denture after tooth extraction in patients with systemic diseases: A clinical report.

For patients with systemic diseases who face difficulties visiting dental clinics, wearing fixed partial denture in the anterior region on the same day of tooth extraction can reduce the total period of treatment and the number of visits, as well as post-treatment psychological effect on the patient.

Influence of diameter and intraradicular post in the stress distribution. Finite element analysis / Influência do diâmetro e do retentor intrarradicular na distribuição de tensões. Análise pelo método dos elementos finitos

Introduction: The biomechanical behavior of endodontically treated teeth depending on the selected restorative material and tooth situation to be restored. Objective: To analyze by the two-dimensional finite element method the biomechanical behavior of different diameters in intraradicular posts and teeth with coronal remaining of 2mm. Material and method: Six models were made with three types of posts, as follows: Glass fiber post, carbon fiber post, and cast metal post, both with diameter # 1 (1.1 mm in diameter) and # 2 (1.3 mm of diameter). The modeling was performed using the Rhinoceros 4.0 program. The FEMAP 10.2 and NEiNastran 9.2 programs were used to develop finite element models. The loading used was 100N for axial and oblique forces. The results were visualized using the von Mises stress map. The statistical analysis was made using analysis of variance (ANOVA) and Tukey post-test, with a significance level of 5%. Result: The oblique loading stress values were higher than the axial loading (p< 0.001) for both situations. The glass fiber post showed the lowest concentrations of stress on both loads (p< 0.001). The carbon fiber post presented significant difference compared to the cast metal post, only in the oblique load (p=0.007). The diameter did not increase the stress of the evaluated posts (p=0.302). Conclusion: The fiber posts were more favorable for restoration of endodontically treated teeth; the increase of diameter did not influence the increase of tension; the oblique load was more harmful for both posts and tooth structure.

Introdução: O comportamento biomecânico de dentes tratados endodonticamente é variável conforme o material restaurador selecionado e situação do dente a ser restaurado. Objetivo: Analisar por meio do método dos elementos finitos bidimensional o comportamento biomecânico de diferentes retentores intrarradiculares e diâmetros em dentes com 2mm de remanescente coronário. Material e método: Foram confeccionados seis modelos com três tipo de retentores: pino de fibra de vidro, pino de fibra de carbono e núcleo metálico fundido, ambos com diâmetro #1 (1,1mm de diâmetro) e #2 (1,3mm de diâmetro). A modelagem foi realizada através do programa Rhinoceros 4.0, e em seguida nos programas FEMAP 10.2 e NeiNastran 9.2 para desenvolvimento d os modelos de elementos finitos. Nos carregamentos foram utilizadas forças de 100N axial e oblíquo. Os resultados foram visualizados pelo mapa de tensão von Mises, e pela análise de variância (ANOVA) e pós-teste Tukey, com nível de significância à 5%. Resultado: O carregamento oblíquo apresentou maiores valores de tensões (p< 0,001). O pino de fibra de vidro apresentou menores concentrações de tensões em ambos os carregamentos (p< 0,001). O pino de fibra de carbono apresentou diferença significativa em relação ao núcleo metálico somente no carregamento oblíquo (p=0,007). O diâmetro não influenciou para o aumento de tensões dos retentores avaliados (p=0,302). Conclusão: Os pinos de fibras são mais favoráveis para restaurações de dentes tratados endodonticamente; O aumento do diâmetro não influenciou no aumento de tensões; A carga oblíqua é mais prejudicial à tanto para o retentor quanto para a estrutura dentária.

Immediate fixed partial denture after tooth extraction in patients with systemic diseases: A clinical report

For patients with systemic diseases who face difficulties visiting dental clinics, wearing fixed partial denture in the anterior region on the same day of tooth extraction can reduce the total period of treatment and the number of visits, as well as post-treatment psychological effect on the patient.

A Fixed Telescopic Prosthesis Designed to Retrieve and Convert to Fixed-Removable Combination Case: A Clinical Report.

This clinical report describes a fixed maxillary telescopic dental prosthesis (FTDP) employing milled base metal copings and a metal superstructure veneered with composite resin, for the restoration in a periodontally compromised patient with uncontrolled diabetes. The telescopic prosthesis framework design incorporated occlusal rest seats in key positions along the arch in case of future posterior tooth loss, in order to be converted to fixed - removable combination prosthesis. The mandible was restored with a conventional fixed ceramo-metal dental prosthesis.

New Knowledge about Zirconium-Ceramic as a Structural Material in Fixed Prosthodontics.

Dental ceramics represents a major structural material in fixed prosthodontics. Increasing demands for esthetics led to development of new ceramic materials in order to eliminate the use of metal framework and for all ceramic restorations with mechanical properties to withstand high occlusal forces. Out of all the present ceramic materials, zirconium-ceramic has the best mechanical properties, and is the only material that can be used for longer span fixed dental restorations. Despite its excellent mechanical properties, to achieve great esthetics, due to absence of translucency, zirconium-dioxide cannot be used as a single material and needs veneering with more esthetic ceramic. When introduced in dental medicine, it was considered an almost ideal material for fixed prosthodontics, but clinical use and in vivo and in vitro studies showed many problems which still persist despite the improvements.This review aims to reveal new developments in zirconium-ceramics and technical procedures which could increase clinical performance and longevity of these restorations.

Estudo comparativo das microdeformações resultantes de cargas estáticas axiais e não axiais em próteses de três elementos implantossuportadas / Comparative study of micro deformations resulting from axial and non-axial static loads under three prosthetic implant elements

Introdução: O controle das microdeformações ao redor dos implantes é um fator que pode levar a uma melhor osseointegração e manutenção das estruturas ósseas. Objetivo: Avaliar a distribuição de tensões ao redor dos implantes, utilizando-se a extensometria, sob a influência da aplicação de cargas estáticas axiais e não axiais em próteses parciais fixas de três elementos, em diferentes pontos de aplicação de carga. Material e Método: Em um bloco de poliuretano, foram instalados três implantes de hexágono interno e, sobre esses implantes, pilares protéticos microunit foram conectados com torque de 20 Ncm. Cilindros plásticos foram utilizados para realização dos enceramentos padronizados que, posteriormente, foram fundidos em liga de cobalto cromo. Extensômetros foram colados na superfície do bloco ao redor dos três implantes. As estruturas metálicas foram parafusadas com torque de 10 Ncm cada. Em seguida, foram realizados carregamentos verticais estáticos de 30 kgf, durante dez segundos, em cinco pontos pré-determinados (A, B, C, D e E), utilizando um dispositivo de aplicação de cargas (DAC). Resultado: Os dados foram analisados pelo teste RM ANOVA, que indicou que o efeito entre o ponto de aplicação de carga e os diferentes corpos de prova não foi estatisticamente significante, enquanto que, para o efeito entre os pontos de aplicação de carga, houve diferença (p=0,0001). Em seguida, aplicou-se o teste de comparação múltipla de Tukey. Conclusão: A aplicação de carga sobre os pontos não axiais D e E produziu um aumento da magnitude de microdeformação ao redor dos implantes. .

Introduction: The control of the micro strain surrounding implants is a factor that can lead to a better osseointegration and maintenance of bone structures. Objective: evaluate in vitro, using strain gauge analysis , the influence of the axial and non-axial static load in implant-supported fixed partial dentures, varying the point of load application. Material and Method: In a block of polyurethane three internal hexagonal implants were installed, on implants abutments microunit were connected with torque of 20 Ncm, and plastic prosthetic cylinders were screwed on to the abutments, which received standard patterns cast in Co-Cr alloy (n=10). Four strain gauges were bonded on the surface of the block tangentially to the three implants. Each metallic structure was screwed onto the microunit with a 10 Ncm torque. With a load application device (DAC) static vertical loads of 30kgf were applied for ten seconds at five predetermined points (A, B, C, D and E). Result: Result analyzed by RM ANOVA, in which the effect of the point of load application and differents specimens were not statistically significant, whereas regarding the points of load application presented statistical differenced (p=0.0001). Applying Tukey's multiple comparison tests. Conclusion: The application of load on the non-axial points D and E produced an increase in the magnitude of micro strain around implants. .

Opciones de tratamiento prótésico en niños con oligodoncias por displasia ectodérmica hidrótica / Prosthetic Treatment Options for Children with Oligodontia due to Hidrotic Ectodermal Dysplasia

La reposición de los dientes no solamente influye en la adecuada alimentación y fonética, sino que también mejora la sonrisa y la apariencia personal, además del aspecto positivo que produce en el estado de salud psicológico y emocional de los niños afectados. Se presentan tres casos clínicos de niños con oligodoncias asociadas a displasia ectodérmica hidrótica, atendidos en la consulta de prótesis de la Clínica Estomatológica de Especialidades de Cienfuegos. Fueron rehabilitados con prótesis parcial removible acrílica, sobredentadura y prótesis parcial fija, respectivamente. Estas constituyen opciones de tratamiento efectivas, que solucionan el problema estético y funcional de los pacientes, y por tanto, mejoran su calidad de vida.

Replacement of teeth not only contributes to adequate nutrition and phonetics, but also improves the smile and appearance, in addition to its positive impact on the psychological and emotional health of the affected children. Three cases of children with oligodontias associated with hidrotic ectodermal dysplasia who were treated at the prosthetics consultation of the Specialized Dental Clinic in Cienfuegos are presented. They were rehabilitated through acrylic removable partial dentures, overdenture and fixed partial denture, respectively. These are effective treatment options that solve the aesthetic and functional problems of the patients, and therefore improve their quality of life.