ABSTRACT
Aim: To evaluate the position, presence, appearance and extent of various anatomical landmarks in the mandibular interforaminal region of Brazilian patients using cone-beam computed tomography (CBCT). Methods: A total of 142 CBCT examinations were analyzed to determine the most common location of the mental foramen (MF), the presence and extent of the anterior loop (AL) of the inferior alveolar nerve, and the appearance and length of the incisive canal (IC). The presence of sexual dimorphism and differences with relation to the left and right sides were also evaluated. Results: Most of the MF (45.5%) was located below the second premolar. The AL and the IC were observed in 18.9 and 96.5% of the images respectively. The average length of AL and IC was 3.14±1.25 mm and 13.68±5.94 mm respectively. No significant differences (p>0.05) between genders or left and right sides were observed for all evaluated parameters. Conclusions: The most common location of the MF, the high rate of visualization of the IC and the occasional presence of AL in the studied Brazilian population demonstrate the importance of using three-dimensional images of the mandibular anterior region, allowing proper surgical planning and preventing injury to the neurovascular bundle.
Subject(s)
Surgery, Oral , Cone-Beam Computed Tomography , Mandible , Mandibular NerveABSTRACT
Pilares angulados frente a fatores biomecânicos adversos, como assentamento não passivo, presença de fenda (gap) e sobrecarga oclusal, podem ter longevidade diminuída devido à falha de componentes, como afrouxamento, soltura e fratura de parafusos. Este trabalho teve como objetivo avaliar à resistência mecânica dos parafusos dos pilares angulados de 25º, com alturas de cinta de 2 mm e 4 mm, submetidos a carregamento axial compressivo, paralelo ao longo eixo do implante, nas plataformas protéticas hexagonais externas (HE) e internas (HI). Nessa análise, 40 implantes e 40 pilares tipo post ou munhão para prótese cimentada foram divididos em quatro grupos de dez: 1) hexágono externo e pilar angulado 25º com cinta de 2 mm (HE2); 2) hexágono externo e pilar angulado 25º com cinta de 4 mm (HE4); 3) hexágono interno e pilar angulado 25º com cinta de 2 mm (HI2); 4) hexágono interno e pilar angulado 25º com cinta de 4 mm (HI4). Cada amostra foi fixada em uma base de aço e levada a uma máquina de ensaios mecânicos para as provas compressivas. Os dados foram tabulados e submetidos à análise de variância Anova dois critérios, com nível de significância de 5%. No grupo HE2, o parafuso do pilar sofreu fratura quando a carga compressiva atingiu 112,21 kgf. No grupo HE4, 120,64 kgf. No grupo HI2, 175,96 kgf. No grupo HI4, 116,03 kgf. A associação do pilar angulado de 25° com cinta de 2 mm ao implante com hexágono interno foi a que apresentou melhor desempenho mecânico. As demais apresentaram resultados semelhantes.
Biomechanical adverse conditions, such as non-passive fit, presence of gaps, and occlusal overload can lead to decrease longevity of angulated abutments due to screw loosening/fracture. The aim of this work was to evaluate the mechanical strength of prosthetic abutments with 2mm and 4mm collar heights under axial compressive static loading over external (EH) and internal (IH) hexagon implant platforms. Forty implants and 40 25-degree angled abutments for cemented prostheses were divided into four groups of ten each as follows: 1) external hex with 2mm collar height (EH2), 2) external hex with 4mm collar height (EH4), 3) internal hex with 2mm collar height (IH2) and, 4) internal hex with 4mm collar height (IH4). Each sample was secured to a stainless steel base and loaded in a universal testing machine until failure. Data was submitted to 2-way ANOVA (5% significance level). Abutment screw fractures were seen for EH2, EH4, IH2, and IH4 at 112.21kgf, 120.64kfg, 175.96kgf, and 116.03kgf, respectively. The use a 25-degree abutment with 2mm collar height (IH2) presented the best mechanical results. Also, similar results were demonstrated for all other groups