Objetivo: As alterações na altura óssea da região posterior ao último implante mandibular em indivíduos reabilitados com próteses fixas implanto suportadas foram correlacionadas com força de mordida (FM) e com a atividade massetérica em função. Métodos: radiografias panorâmicas antes e 1 ano depois da reabilitação de 10 pacientes do Hospital de Reabilitação de Anomalias Craniofaciais (HRAC – USP), foram avaliadas quanto à presença de alteração dimensional óssea. A FM foi registrada por meio de um gnatodinamômetro. Eletromiografia dos masseteres foi realizada e traduzida pelos parâmetros: contração voluntária isométrica máxima (CVIM) durante 5 segundos, mastigação habitual de cenoura (MHC) e mastigação unilateral direita (MUD) e esquerda (MUE) com látex. Resultados: houve um aumento médio da altura óssea mandibular de 0,23 ±0,4 mm; a FM média foi 42 ±5,9 Kgf e a CVIM foi de 66,7 ±23,7 µV. Os valores médios para MHC foram: ato 0,52 ±0,02 s; ciclo 1,3± 0,67s e amplitude (potência) 85,98 ±19,53µV; para MUD com látex foram: ato 0,59s, ciclo 0,89 ±0,22s amplitude 86,93 ±26,67µV, e os da MUE com látex foram: ato 0,56s, ciclo 1,35 ±0,69s e amplitude 90,89 ±32,96µV. Somente houve significância estatística do lado direito entre alteração dimensional óssea e o ato da MHC (p= 0,036); do lado esquerdo com o ato da MUD com látex - lado de balanceio (p= 0,026). Conclusão: o aumento médio da altura óssea na região posterior da mandíbula não se correlacionou significantemente com a maioria dos parâmetros analisados, sugerindo que a duração, mais que a potência da atividade muscular pode ter influência nas alturas observadas. / Objectives: Changes on mandibular high posterior to the most distally positioned implant on patients provided with implant-supported fixed prosthesis were related to bite force (FM) and functional maseteric activity. Methods: orthopantograms taken before and one year after rehabilitation of 10 patients from the Hospital for Rehabilitation of Craniofacial Anomalies (HRAC-USP) were evaluated. The FM was registered by a gnatodynamometer. Electromyography of masseteric muscle was performed and interpreted as follows: maximum voluntary isometric clench (CVIM) during 5 seconds, habitual chewing of carrot (MHC) and unilateral right (MUD) and left (MUE) chewing with latex. Results: there was a mean increases in mandibular bone high of 0,23 ± 0,4mm; the mean FM was 42 ±5,9Kgf and CVIM was 66,7 ± 23,7 µV. The mean values for MHC were: act 0,52± 0,02s; cycle 1,3± 0,67s and the voltage amplitudes 85,98± 19,53µV; for MUD with latex the values were: act 0,59s, cycle 1,35 ± 0,69s and voltage amplitudes 90,89± 32,96µV. There was only statistically significant difference between dimensional bone changes and act of MHI (p= 0,036) for the right side; and for the left side between MUD act with latex and balance side (p=0,026). Conclusions: the mean increase on bone high observed at the posterior region of the mandible was not significantly related to the majority of the analyzed parameters. This suggests that the lasting more than the amplitude of the muscular activity may have influenced the measurements observed.

Orientador: Lafayette Nogueira Junior / Banca: Tarcísio José de Arruda Paes Junior / Banca: Fernanda de Cassia Papaiz Gonçalves / Banca: Rodrigo Máximo de Araújo / Banca: Jean Soares Miranda / Resumo: A sobrecarga do hexágono durante a inserção dos implantes dentários de hexágono externo pode gerar danos irreversíveis ao mesmo ocasionando problemas futuros na reabilitação. Sendo assim, esse trabalho teve por objetivo avaliar a deformação e resistência ao contra-torque dos hexágonos com o uso de um montador modificado proposto pelo autor para inserção dos implantes tipo hexágono externo (HE) tendo como hipótese de que o montador modificado apresente resultados diferentes do montador padrão. Para isso, 44 implantes foram divididos em dois grupos, controle (montador normal MN; n=12) e o teste (montador modificado MM; n=12), e foram submetidos ao teste de torção seguindo os parâmetros da norma ISO 13498:2013. Em seguida, a deformação dos hexágonos e possíveis deformações causadas às roscas internas dos implantes foram analisadas, respectivamente, de forma qualitativa por meio de microscopia eletrônica de varredura. Já para o teste de fadiga, controle (MN; n=10) e teste (MM; n=10), os parâmetros utilizados foram da norma ISO 14801:2007. Ao final de 1,2 x 106 (4Hz) ciclos, o valor de destorque dos pilares foi registrado. A desadaptação da junta pilar/implante foi avaliada qualitativamente por meio da microscopia MEV. Como resultados pudemos observar maior manutenção da estrutura da conexão pelo grupo MM comparado ao grupo MN, sugerindo-se que o grupo MM apresentaram comportamento mais seguro e previsível quando comparado ao grupo MN / Abstract: Hexagon overload during the insertion of external hexagon dental implants can lead to irreversible damage, leading to future problems in rehabilitation. Thus, this study aimed to evaluate the deformation and reverse torque resistance of hexagons with the use of a modified mount proposed by the author for insertion of external hexagon (HE) implants with the hypothesis that the modified mount presents different results compared to the default assembler. For this, 44 implants were divided into two groups, control (normal mount MN; n = 12) and the test (modified mount MM; n = 12), and were submitted to torsion testing following the parameters of ISO 13498: 2013. Then, the deformation of the hexagons and possible deformations caused to the internal threads of the implants were analyzed qualitatively, respectively by scanning electron microscopy. For the fatigue test, control (MN; n = 10) and test (MM; n = 10), the parameters used were from ISO 14801: 2007. At the end of 1.2 x 106 (4Hz) cycles, the abutment value of the abutments was recorded. Abutment of the abutment / implant joint was qualitatively evaluated by SEM microscopy. As a result we could observe a better maintenance of the connection structure by the MM group compared to the MN group, suggesting that the MM group presented a safer and more predictable behavior when compared to the MN group / Doutor

Orientador: Fellippo Ramos Verri / Resumo: O objetivo deste estudo foi avaliar a distribuição de tensão e deslocamento em implantes de diâmetro reduzido em reabilitações unitárias em região maxilar anterior, variando o posicionamento do implante (ao nível ósseo e 1,5 mm infra-ósseo), através do método de elementos finitos tridimensionais (MEF-3D). Quatro modelos 3D representando uma hemisecção do lado direito da região anterior da maxila foram simulados com a presença de coroa cimentada sobre implante (cone morse) de 10mm de comprimento, variando-se o diâmetro do implante (2,9 mm e 3,5 mm) e a instalação dos implantes no tecido ósseo em rebordo alveolar de 4,5 mm de espessura. O modelo ósseo tridimensional foi construído por recomposição tomográfica com uso dos softwares Invesalius e Rhinoceros 3D. O implante e os componentes foram modelados a partir de modificações do formato original no programa SolidWorks e finalizados no Rhinoceros, bem como o desenho da coroa simulada. A discretização dos modelos foi feita no software ANSYS 19.2, incluindo caracterização dos materiais, contatos, elaboração das malhas, condições de carregamento (178N em direção de 0, 30 e 60 graus em relação ao longo eixo do implante) e de contorno (com restrição em direção x, y, z nas secções laterais dos modelos). Os resultados mostraram comportamento biomecânico similar, com diminuição dos níveis de deslocamento e estresse para implantes de 3,5 mm e implantes infra-ósseos, muito embora os valores obtidos estiveram dentro de valores fisiológicos... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Abstract: The Aim of this study was to evaluate the distribution of stress on implants of narrow diameter, in single unit cemented crowns in the anterior maxillary region, varying the position of the implant (at the bone level and 1.5 mm infra-osseous), through the 3D finite element analysis (3D-FEA). Four 3D models representing a right hemisection of the anterior maxillary region were simulated with the presence of a cemented crown over a 10mm long implant (morse cone), with the implant diameter varying among 2.9 mm and 3.5 mm in an simulated alveolar ridge of 4,5mm thickness. The bone of 3D models was simulated by tomographic recomposition using the software Invesalius and Rhinoceros 3D. The implant and components were modeled from modifications of the original design in the SolidWorks software and modeled in the Rhinoceros, as well as the design of the simulated crown. The discretization of the models was done in the ANSYS 19,2 software, including characterization of materials, contacts, meshes, loading conditions (178N towards 0, 30 and 60 degrees in relation to the implant long axis) and boundary conditions in the x, y, z direction in the lateral sections of the models). The results of dislodgment and von Mises showed similar maps distribution, decreasing dislodgment and stress in implants of 3,5mm diameter and in infra-osseous position, besides these results were inside physiologic values. It was possible to conclude that 2.9mm implants were no more biomechanically favo... (Complete abstract click electronic access below) / Mestre

Objectives: To compare the osseointegration of conventionally and immediately restored tapered implants in a split-mouth animal model, and to compare different methods of analysis for measuring osseointegration. Materials & Methods: Twenty tapered implants were placed in the posterior mandibles of ten sheep, three months after premolar extractions. Ten control implants were placed and were restored after three months submerged healing. Ten test implants were placed on the contralateral side at this time and immediately restored. Animals were sacrificed after a further three months healing. Resonance frequency analysis (Implant Stability Quotient, ISQ), and standardized radiographs were taken at all stages. Alveolar bone height relative to the implant shoulder was measured on digitized radiographs. Histomorphometric and micro-Computed Tomograph ([mu]CT) morphometric analysis for Bone-to-Implant Contact (BIC) and Bone Density (BD) were performed. Radiographic, stability and morphometric measurements were compared statistically. Results: Only three (30%) of conventionally restored and two (20%) immediately restored implants survived (p = 0.74). Mean crestal bone level after three months loading differed significantly (control 5.3 � 0.9 mm versus test 0.9 � 1.3 mm; p = 0.02). Control implants lost more crestal bone over three months than test implants but this was not statistically significant (3.5 � 1.0 mm versus 0.7 � 1.0 mm; p = 0.06). The test group showed a higher mean ISQ value (85.4 � 6.9) compared to the control group (72 � 14.4; p = 0.349). Both groups showed a slightly reduced stability during the loaded period. This was more marked for the test group but not statistically significant (-0.5 � 3.8 ISQ versus -4.35 � 6.6 ISQ; p = 0.8). A statistically significant negative correlation was found between the loss of crestal bone and ISQ with loading (Pearson�s coefficient of correlation r = -0.473 p = 0.026). Both groups showed a statistically significant difference in BIC for both histomorphometric analaysis (HMA); p = 0.039 and [mu]CT morphometric analysis; p = 0.013. When the two forms of morphometric analysis were compared, HMA and [mu]CT morphometric analysis differed significantly for both BIC (p = 0.05) and BD (p = 0.048). However, a statistically significant correlation was found between the two measuring techniques, for both BIC (r = 0.335 p = 0.013) and BD (r = 0.439 p = 0.01). Conclusions: The placement of wide-bodied 3i Osseotite NT[TM] tapered implants into sheep mandible resulted in high failure rate regardless of the loading protocol. The sheep mandibular model may be inappropriate as a model for evaluation of immediate loading, and to test implants which are designed for soft bone. Further investigations are needed to look into the variations in bone microstructure along with their impact on the mechanics of implant-bone union. Although a statistically significant difference was found between the two measurement techniques, a positive correlation was found between HMA and [mu]CT morphometric analysis suggesting non-invasive methods may have a potential in assessing osseointegration. Further research is required to optimize the variables in [mu]CT analysis, such as, voltage, filters, and thresholding to minimize artifacts and to maximize bone contrast when titanium implants are present.

<p>Objectives: Temperature changes along an implant body have not been widely studied. The objectives of this in vitro study were (i) to establish if the temperature of the abutment influences the temperature of the implant surface, (ii) to establish the temperature transmission from abutment to implant body, and (iii) to establish for what abutment temperature the critical time/temperature threshold of 47oC for 1 minute at implant level is reached.</p>

published_or_final_version / Dental Surgery / Master / Master of Dental Surgery

<p>Objectives: Temperature changes along an implant body have not been widely studied. The objectives of this in vitro study were (i) to establish if the temperature of the abutment influences the temperature of the implant surface, (ii) to establish the temperature transmission from abutment to implant body, and (iii) to establish for what abutment temperature the critical time/temperature threshold of 47oC for 1 minute at implant level is reached.</p>

Objectives: To compare the osseointegration of conventionally and immediately restored tapered implants in a split-mouth animal model, and to compare different methods of analysis for measuring osseointegration. Materials & Methods: Twenty tapered implants were placed in the posterior mandibles of ten sheep, three months after premolar extractions. Ten control implants were placed and were restored after three months submerged healing. Ten test implants were placed on the contralateral side at this time and immediately restored. Animals were sacrificed after a further three months healing. Resonance frequency analysis (Implant Stability Quotient, ISQ), and standardized radiographs were taken at all stages. Alveolar bone height relative to the implant shoulder was measured on digitized radiographs. Histomorphometric and micro-Computed Tomograph ([mu]CT) morphometric analysis for Bone-to-Implant Contact (BIC) and Bone Density (BD) were performed. Radiographic, stability and morphometric measurements were compared statistically. Results: Only three (30%) of conventionally restored and two (20%) immediately restored implants survived (p = 0.74). Mean crestal bone level after three months loading differed significantly (control 5.3 � 0.9 mm versus test 0.9 � 1.3 mm; p = 0.02). Control implants lost more crestal bone over three months than test implants but this was not statistically significant (3.5 � 1.0 mm versus 0.7 � 1.0 mm; p = 0.06). The test group showed a higher mean ISQ value (85.4 � 6.9) compared to the control group (72 � 14.4; p = 0.349). Both groups showed a slightly reduced stability during the loaded period. This was more marked for the test group but not statistically significant (-0.5 � 3.8 ISQ versus -4.35 � 6.6 ISQ; p = 0.8). A statistically significant negative correlation was found between the loss of crestal bone and ISQ with loading (Pearson�s coefficient of correlation r = -0.473 p = 0.026). Both groups showed a statistically significant difference in BIC for both histomorphometric analaysis (HMA); p = 0.039 and [mu]CT morphometric analysis; p = 0.013. When the two forms of morphometric analysis were compared, HMA and [mu]CT morphometric analysis differed significantly for both BIC (p = 0.05) and BD (p = 0.048). However, a statistically significant correlation was found between the two measuring techniques, for both BIC (r = 0.335 p = 0.013) and BD (r = 0.439 p = 0.01). Conclusions: The placement of wide-bodied 3i Osseotite NT[TM] tapered implants into sheep mandible resulted in high failure rate regardless of the loading protocol. The sheep mandibular model may be inappropriate as a model for evaluation of immediate loading, and to test implants which are designed for soft bone. Further investigations are needed to look into the variations in bone microstructure along with their impact on the mechanics of implant-bone union. Although a statistically significant difference was found between the two measurement techniques, a positive correlation was found between HMA and [mu]CT morphometric analysis suggesting non-invasive methods may have a potential in assessing osseointegration. Further research is required to optimize the variables in [mu]CT analysis, such as, voltage, filters, and thresholding to minimize artifacts and to maximize bone contrast when titanium implants are present.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Thesis (M.S.)--University of Michigan, 1977.