Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1) parallel vertical implants, and 2) tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm). The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. RESULTS: Abutment #1 (adjacent to the cantilever) had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. CONCLUSION: The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments

Preload and torque removal evaluation of three different abutment screws for single standing implant restorations

Several authors still consider the mechanical problems of fracture and component loosening as the main causes of failure of implant-supported restorations. The purpose of this in vitro study was to compare the preload of three types of screw for transmucosal abutment attachment used in single implant-supported prosthesis through strain gauge and removal torque measurements. Three external hex fixtures were used, and each received a transmucosal abutment (Cera One®), which was fixed to the implant with its respective screw: Group A- gold screw, Group B- titanium screw and Group C- surface-treated titanium screw (Ti-Tite®). Ten screws of each type were attached applying a 30.07±0.28 Ncm torque force and maintained in position for 5 minutes. After this, the preload values were measured using strain gauges and a measurement cell. Gold screws presented higher preload values (131.72±8.98 N), followed by surface-treated titanium screws (97.78±4.68 N) and titanium screws (37.03±5.69 N). ANOVA (

The effect of laser on the stimulation of bone-implant interaction: an experimental study in rabbits

Purpose: To assess osseointegration by measuring the removal torque of smooth cylindrical implants placed in rabbit tibiae, having been subjected, or not, to low-intensity laser irradiation (GaAlAs). Methods: Two implants were inserted into one tibiae of 16 male New Zealand rabbits weighing 3.5-4.0 kg; the animals were divided into four groups (control and laser at 16 and 30 days of wound healing). In the irradiated groups, laser was applied at a 830-nm wavelength, in continuous mode and with 100 mW of potency, and the applications were punctual, with 1 J/cm3 on three points, and were repeated eight times at 48-hour intervals starting immediately after implantation surgery, thus totaling 24 J/cm2. After the wounds healed, the animals were sacrificed, the tibiae were removed, implant removal torques were measured by means of a handheld digital torque-meter, and a factorial variance analysis statistical test was applied. Results: There was significant intergroup difference regarding time as a single factor. The removal torque observed in the control groups was, for smooth implants, 20.42±3.06 N/cm at 16 days and 27.42±19.65 N/cm at 30 days; in the irradiated groups, the removal torque for smooth implants was 19.15±4.65 N/cm at 16 days and 30.08±4.14 N/cm at 30 days. Conclusion: Removal torque values were higher at 30 days than at 16 days, independent of laser application.Objetivo: Avaliar a osseointegração através do torque de remoção de implantes cilíndricos lisos, colocados em tíbias de coelhos, submetidos ou não à irradiação com laser de baixa intensidade (AsGaAl). Metodologia: Foram utilizados 16 coelhos machos da raça Nova Zelândia, pesando entre 3,5 a 4,0 quilos, sendo inseridos dois implantes em uma tíbia, dividida em quatro grupos (controle e laser para 16 e 30 dias de cicatrização). No grupo irradiado foi aplicado laser com comprimento de onda de 830 nm, modo contínuo e potência de 100 mW, sendo a aplicação pontual de 1 J/cm² em três pontos e oito aplicações, com intervalo de 48 horas, iniciada imediatamente após a cirurgia de colocação dos implantes, perfazendo um total de 24 J/cm². Após o período de cicatrização, os animais foram sacrificados, e então, realizada a remoção das tíbias e, em seguida, a medição dos torques para remoção dos implantes com torquímetro digital manual, aplicando-se o teste estatístico de Análise de Variância Fatorial. Resultados: Foi verificado que existe diferença significativa intra-grupos em relação ao fator isolado tempo. O torque de remoção obtido para o grupo controle: Implantes lisos com 16 dias (20,42±3,06 N/cm) e 30 dias (27,42±19,65 N/cm); e para o grupo irradiado: Implantes lisos com 16 dias (19,15±4,65 N/cm) e 30 dias (30,08±4,14 N/cm). Conclusão: Os valores do torque de remoção no período de 30 dias são superiores ao período de 16 dias, independentemente da aplicação de laser

Effect of the number of abutments on biomechanics of Branemark prosthesis with straight and tilted distal implants

OBJECTIVE: This study aimed to evaluate the bending moments, and compressive and tensile forces in implant-supported prostheses with three, four or five abutments. MATERIAL AND METHODS: Ten Pd-Ag frameworks were tested over two master models with: 1) parallel vertical implants, and 2) tilted distal implants. Strain gauges were fixed on the abutments of each master model to measure the deformation when a static load of 50 N was applied on the cantilever (15 mm). The deformation values were measured when the metallic frameworks were tested over three, four or five abutments, and transformed into force and bending moment values. Data were analyzed by ANOVA and Tukey's test for multiple comparisons at 5% level of significance. RESULTS: Abutment #1 (adjacent to the cantilever) had the highest values of force and sagittal bending moment for all tests with three, four or five abutments. Independently from the number of abutments, axial force in abutment #1 was higher in the vertical model than in the tilted model. Total moment was higher with three abutments than with four or five abutments. Independently from the inclination of implants, the mean force with four or five abutments was lower than that with three abutments. CONCLUSION: The results suggest that in the set-ups with four or five abutments tilted distal implants reduced axial force and did not increase bending moments