Abstract Objectives: This experimental laboratory study aimed to compare the effect of four external irrigation protocols on bone tissue heating during guided implant drilling. Methods: Forty perforations were made in ten bovine rib specimens using customized surgical templates. Four experimental groups (n=10/group) were tested: Control group = 10-ml syringe with 25°C saline solution, Group 1 = 10-ml syringe with 10°C saline solution, Group 2 = combined external irrigation using a handpiece and a 10-ml syringe with 25°C saline solution, and Group 3 = combined external irrigation using a handpiece and a 10-ml syringe with 10°C saline solution. The temperature was measured at cervical and apical points using K-type thermocouples, a digital thermometer, and a video recorder. Data were analyzed by ANOVA and Pearson’s correlation coefficients (alpha=0.05). Results: The maximum temperature was 42°C (cervical) and 44°C (apical). No difference in temperature changes was found among groups, but the difference between bone specimens was statistically significant. Temperature and time were positively associated for most groups, mainly in the cervical region. Conclusions: All irrigation methods were equally effective in controlling the bone temperature in cervical and apical regions. However, longer drilling times caused a greater increase in temperature.

Resumo Objetivos: Este estudo experimental de laboratório teve como objetivo comparar o efeito de quatro protocolos de irrigação externa no aquecimento do tecido ósseo durante a perfuração guiada de implantes. Métodos: Quarenta perfurações foram feitas em dez peças de costelas bovinas utilizando guias cirúrgicas personalizadas. Quatro grupos experimentais (n=10/grupo) foram testados: Grupo controle = seringa de 10 ml com solução salina 25°C, Grupo 1 = seringa de 10 ml com solução salina 10°C, Grupo 2 = irrigação externa combinada usando peça de mão e seringa de 10 ml com solução salina 25°C, e Grupo 3 = irrigação externa combinada com peça de mão e seringa de 10 ml com solução salina 10°C. A temperatura foi medida nos pontos cervical e apical, utilizando termopares tipo K, termômetro digital e videogravador. Os dados foram analisados por ANOVA e coeficientes de correlação de Pearson (alfa=0,05). Resultados: A temperatura máxima foi de 42°C (cervical) e 44°C (apical). Nenhuma diferença nas mudanças de temperatura foi encontrada entre os grupos, mas a diferença entre os espécimes ósseos foi estatisticamente significativa. Temperatura e tempo estiveram positivamente associados para a maioria dos grupos, principalmente na região cervical. Conclusões: Todos os métodos de irrigação foram igualmente eficazes no controle da temperatura óssea nas regiões cervical e apical. No entanto, tempos de perfuração mais longos tiveram um aumento maior na temperatura.

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.

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.

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.

OBJETIVO: Determinar a acurácia de diferentes métodos radiográficos para estimação de altura óssea na região do forame mentual. METODOLOGIA: Vinte hemi-mandíbulas humanas, secas, foram examinadas por radiografia periapical e panorâmica e tomografia computadorizada. Um paquímetro digital foi usado para medir os traçados obtidos das radiografias em três diferentes tempos (grupos A1, A2 e A3) e nas hemi-mandíbulas seccionadas transversalmente (grupo B). As medições foram: Medida 1 - do limite superior da crista óssea ao limite superior do forame mentual; Medida 2 - do limite superior do forame mentual ao limite inferior do osso cortical da base da mandíbula; Medida 3 - do limite superior da crista óssea ao limite inferior do osso cortical da base da mandíbula. Os dados foram analisados por teste t de Student e teste de Friedman. RESULTADOS: Os valores médios de diferença na Medida 1 foram 0,33 mm, 0,35 mm e 0,85 mm para a radiografia periapical, tomografia computadorizada e radiografia panorâmica, respectivamente (intervalos de confiança de 0,17 a 0,49 mm, 0,18 a 0,53 mm e 0,38 a 1,32 mm, respectivamente). As radiografias panorâmicas mostraram as maiores diferenças nas Medidas 2 e 3, com valores médios de 1,05 mm e 1,93 mm, respectivamente. CONCLUSÃO: A radiografia periapical e a tomografia computadorizada mostraram a melhor acurácia. Sugere-se uma margem de segurança em caso de cirurgias.

PURPOSE: To determine the accuracy of different radiographic methods for bone height estimation at the mental foramen area. METHODS: Twenty dry human hemimandibles were examed by using periapical and panoramic radiography, and computed tomography. An electronic digital caliper was used to measure the tracings obtained from the radiographies in three different times (groups A1, A2 and A3) and in the cross-sectioned hemimandibles (group B). Measurements consisted of: Measure 1 - from the upper limit of the alveolar ridge to the upper limit of the mental foramen; Measure 2 - from the upper limit of the mental foramen to the inferior limit of the cortical bone of the base of the jaw; Measure 3 - from the upper limit of the alveolar ridge to the inferior limit of the cortical bone of the base of the jaw. Data were analyzed with Student-t and Friedman tests. RESULTS: The average difference values in Measure 1 were 0.33 mm, 0.35 mm and 0.85 mm for the periapical radiography, computed tomography and panoramic radiography, respectively (confidence intervals of 0.17 mm to 0.49 mm, 0.18 mm to 0.53 mm and 0.38 mm to 1.32 mm, respectively). Panoramic radiographies showed the greatest differences in Measures 2 and 3, with average values of 1.05 mm and 1.93 mm, respectively. CONCLUSION: Periapical radiography and computed tomography showed the best accuracy. A safety margin for surgical purposes has been suggested.

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 (p<0.05) and Tukey's test (p<0.05) were applied. Statistically significant differences were found among the groups for both preload and removal torque values. In conclusion, gold screws may be indicated to achieve superior longevity of the abutment-implant connection and, consequently, prosthetic restoration due to greater preload values yielded.