Mechanical behavior of a prosthetic connection modifier (MCP) for dental implants

Considering the positive aspects of Morse taper (MT) connection and searching for solutions of problems with deep implants of external hexagon implants (EH), the purpose of this study was to analyze qualitatively and quantitatively, through Scanning Electron Microscopy (SEM), Mechanical Cycling, tightening and loosening torque of prosthetic components by a digital torquemeter, Optical Microscopy (OM) and Digital Radiography, the use of an abutment - Prosthetic Connection Modifier (MCP), adapted to EH implants allowing its connection to be converted into a MT type. Thirty EH implants were inserted into polystyrene resin blocks and divided into two groups: MCP group formed by crown/abutmentMT/MCP/implant (n = 15) and Abutment (ABT) Group formed by crown/abutmentEH/implant (n = 15), five specimens from each group composed the control group that was not submitted to fatigue testing. For characterization and qualitative analysis, all components were submitted to Scanning Electronic Microscopy (SEM) and Optical Microscopy (OM) before and after mechanical cycling, and for control group before and after screw loosening. To verify tightening and loosening torque, all thirty specimens were taken to the MK Control torquemeter and for the fatigue test 10 specimens of each group were subjected to mechanical cycling (1,200,000 cycles) subjected to a force of 50 N at a frequency of 2Hz with an inclination of 30 ° according to ISO 14801. For statistics evaluation a significance level of α = 0.05 was used and parametric and non-parametric tests were performed. SEM images were analyzed qualitatively and for all groups before cycling were observed machining residues and after cycling were found slight morphology discrepancies in the hexagons. After cycling, there was no occurrence of loosening or axial displacement of prosthesis evaluated by digital radiographs. After statistical evaluation among groups and intra-group, comparing the initial and loosening torque, evaluation of the mean of internal area of the hexagon and evaluation of the internal length of the circumference, statistically significant differences were observed only for the ABT Group. The MCP group did not present loosening after mechanical cycling, which means that MCP showed better results in adaptation and retention when compared to the other group and MCP presents satisfactory mechanical characteristics to its applicability.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorDissertação (Mestrado)Considerando os aspectos positivos da Conexão Morse e para solucionar problemas de posicionamento profundo de implantes Hexágono Externo (HE), esse estudo propõe analisar qualitativamente e quantitativamente por meio de Microscopia Eletrônica de Varredura (MEV), método de Ciclagem Mecânica, aperto e desaperto do parafuso por torquímetro digital, Microscopia Óptica e Radiografias Digitais, o uso de um abutment Modificador de Conexão Protética (MCP) adaptado a implantes Hexágono Externo (HE), transformando sua conexão em tipo Cone Morse (CM). Trinta implantes HE foram incluídos em blocos de resina, sendo divididos em dois grupos: Grupo MCP formado por coroa/abutmentCM/MCP/implante (n=15) e Grupo ABT formado por coroa/abutmentHE/implante (n=15), sendo que 5 amostras de cada grupo formaram o grupo controle que não foi submetido a teste de fadiga. Para a caracterização e análise qualitativa todos os componentes foram submetidos a Microscopia Eletrônica de Varredura e Óptica pré e pós ciclagem mecânica e para o grupo controle pré e pós desaperto do parafuso. Foi avaliado o torque de aperto e desaperto dos parafusos dos 30 conjuntos utilizando um torquímetro Control MK e para o teste de fadiga 10 conjuntos de cada grupo foram submetidos à ciclos mecânicos (1.200.000 ciclos) onde foi aplicada uma força de 50N a uma frequência de 2Hz com inclinação de 30° segundo a norma ISO 14801. Para a análise estatística foi utilizado um nível de significância de α=0,05 e realizado testes paramétricos e testes não paramétricos. As imagens de microscopia eletrônica de varredura foram analisadas qualitativamente e para todos os grupos foram observados antes da ciclagem resíduos de usinagem e após a ciclagem pequenas discrepâncias na morfologia dos hexágonos. Após a ciclagem observou-se a não ocorrência de desaperto do parafuso ou deslocamento axial das próteses avaliadas por radiografias digitais. Após a avaliação estatística intra grupo e entre grupos comparando torque inicial e desaperto, avaliação da média da área interna dos hexágonos e avaliação média do comprimento da circunferência ao redor do hexágono foram observadas diferenças estatisticamente significantes apenas para o grupo ABT. O grupo MCP não apresentou afrouxamento após o ciclismo mecânico apresentando os melhores resultados em relação a adaptação e retenção em comparação com o outro grupo e apresenta características mecânicas adequadas a sua aplicabilidade

Immediate prosthetic rehabilitation of lower molars with hybrid internal tapered implants: report of two cases

ABSTRACT The immediate rehabilitation of the posterior region of the mandible with dental implants, expands the set of possible actions for the dental surgeon, in the face of tooth loss. The purpose of this study is to describe two cases of single rehabilitation of mandibular molars with hybrid internal tapered implants indicated for immediate loading in post-extraction socket, associated with the maintenance of the prosthetic and peri-implant space. Implants with macrogeometry and surface treatment (Hydrophilic) were used to optimize primary stability, as well as the type of internal connection and prosthetic abutments that allows better accommodation and healing of adjacent tissues, and protection of the bone graft. Different methodologies of surgical guides did not influence the final result. The predictability of associating techniques and components can be observed in the 2-year follow-up. The initial planning combined with the new technologies enable to achieve stable and functional final restorations

Mechanical Behavior of One-Piece and Two-Piece Tapered Prosthetic Abutments with 11.5 and 16 Degrees

The objective of this study is to examine the mechanical behavior of two-piece abutments (Morse taper with 16° internal angulation and Morse taper with 11.5° internal angulation) before and after cyclic fatigue testing, following ISO 14801:2016 guidelines. The specimens were divided into three groups: a modified Morse taper with a taper angle of 16° (GM group), a conventional Morse taper (taper angle of 11.5° deg) with a two-piece (CMt group), and one-piece abutments (CMo group). Each experimental group was formed by ten implants and ten abutments (n = 10) for a total of 30 specimens (n = 30). The abutments were tightened and loosened, and a fatigue test was applied with 15 Hz and 5 × 106 cycles. Subsequently, the abutments were loosened, and a pull-out test was performed on the CMt group. Finite element analysis (FEA) was conducted on stress concentration regions. The statistical analysis of the loosening test was performed using two-way ANOVA and Tukey’s tests (p p p p = 0.840). In the pull-out test of the CMt group, the sample exhibited frictional locking only after fatigue (mean = 94.2 N). The FEA demonstrated a varied stress distribution in all groups. The stress was found to be more concentrated in the upper third and middle third regions of the implant, as well as in the opposite region of the load application for all three groups. Although the CMo group showed lower rates of loosening, it displayed a poorer stress distribution in comparison to the GM and CMt groups. On the other hand, the CMt group exhibited a satisfactory frictional lock after undergoing the fatigue tests