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1.
Comput Methods Biomech Biomed Engin ; 23(13): 1034-1040, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32619356

RESUMEN

This study aimed to investigate the effect of miniscrews thread shape on the stress distribution receiving a torque load. Seven thread shapes (S,V1,V2,B1,B2,R1,R2) models were constructed and a 6 Nmm-torque load was applied. The order of maximum equivalent stress (EQV) value was V1 > V2 > B1 > R1 > R2 > B2 > S. The order of maximum displacement of miniscrew (Max DM) value was S > B2 > R1 = V1 > B1 > V2 > R2. Model R2 may be the most appropriate thread shape affording a torque force.


Asunto(s)
Tornillos Óseos , Análisis de Elementos Finitos , Diseño de Aparato Ortodóncico , Estrés Mecánico , Torque , Fenómenos Biomecánicos , Hueso Cortical/patología , Análisis del Estrés Dental , Humanos
2.
PLoS One ; 10(12): e0144744, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26659581

RESUMEN

BACKGROUND: Stress on the bone surrounding dental micro-implants affects implant success. PURPOSE: To compare the stress on the bone surrounding a micro-implant after application of a single force (SF) of 200 g or a composite force (CF) of 200 g and 6 N.mm torque. MATERIALS AND METHODS: Finite element models were developed for micro-implant diameters of 1.2, 1.6, and 2.0 mm, and lengths of 6, 8, 10, and 12 mm and either a SF or CF was applied. The maximum equivalent stress (Max EQS) of the bone surrounding the micro-implant was determined, and the relationships among type of force, diameter, and length were evaluated. RESULTS: The Max EQS of the CF exceeded that of the SF (P< 0.05). The effect of force on stress was related to implant diameter, but not to implant length. The larger CF led to greater instability of the micro-implant and the effect was most pronounced at an implant diameter of 1.2 mm. The use of implant diameters of 1.6 mm and 2.0 mm produced no significant difference in implant stability when either a CF or SF was applied. CONCLUSION: When considering the use of an implant to perform three-dimensional control on the teeth, the implant diameter chosen should be > 1.2 mm.


Asunto(s)
Implantes Dentales , Análisis del Estrés Dental , Análisis de Elementos Finitos , Modelos Anatómicos , Fenómenos Biomecánicos , Fuerza Compresiva , Diseño de Prótesis Dental , Humanos , Mandíbula/anatomía & histología , Mandíbula/cirugía , Maxilar/anatomía & histología , Maxilar/cirugía , Estrés Mecánico , Torque
3.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 48(1): 37-40, 2013 Jan.
Artículo en Zh | MEDLINE | ID: mdl-23534520

RESUMEN

OBJECTIVE: To investigate the influence of the diameter and length of the mini-implant on the primary stability after loading with composite forces (CF) which contained torque and horizontal forces (HF). METHODS: Ninety-six finite element models were established by the combination of mini-implant and bone, diameters (1.2 mm, 1.6 mm, 2.0 mm) and length (6 mm, 8 mm, 10 mm, 12 mm). There were 12 sizes, each size corresponded with 8 models. Group HF (each size n = 4) was loaded with 1.96 N horizontal force and Group CF (each size n = 4) was loaded with composite force which contained 6 N·mm torque and 1.96 N horizontal force. The maximum displacement of mini-implant with different force directions, implant diameters and lengths were evaluated. RESULTS: The effect of force direction on the displacement related to diameter of mini-implant. The maximum displacement under load with HF respectively was changed with the changing of diameter[1.2 mm: (7.71 ± 0.49) µm; 1.6 mm: (3.94 ± 0.31) µm; 2.0 mm: (2.32 ± 0.43) µm], which were smaller than the maximum displacement of Group CF [1.2 mm: (9.22 ± 0.63) µm; 1.6 mm: (4.62 ± 0.52) µm; 2.0 mm: (2.69 ± 0.49) µm] (P < 0.05). When diameter was 1.2 mm, the difference of the maximum displacement [(1.61 ± 0.22) µm] between Group HF and CF was more obvious than that when the diameter was 1.6 mm or 2.0 mm [(0.64 ± 0.12), (0.49 ± 0.06) µm] (P < 0.05). CONCLUSIONS: The composite force had unfavorable effect on the primary stability of the mini-implant. The diameter of the mini-implant had better be larger than 1.2 mm when the composite forces were applied.


Asunto(s)
Análisis de Elementos Finitos , Métodos de Anclaje en Ortodoncia/instrumentación , Torque
4.
Artículo en Inglés | MEDLINE | ID: mdl-19748293

RESUMEN

OBJECTIVE: We compared the anesthetic efficacy of inferior alveolar nerve block (IANB) plus buccal infiltration (BI) and IANB plus periodontal ligament (PDL) articaine injections in patients with irreversible pulpitis in the mandibular first molar. STUDY DESIGN: Fifty-seven volunteers, patients with irreversible pulpitis in the mandibular first molar admitted to the Department of Stomatology, Second Affiliated Hospital, Sun Yat-Sen University, randomly received conventional IANB, containing 1.7 mL 4% articaine/HCl with 1:100,000 epinephrine, plus either BI or PDL injections containing 0.4 mL articaine/HCl with 1:100,000 epinephrine. The patients recorded the pain of the injections and endodontic access on a Heft-Parker visual analog scale (VAS). RESULTS: According to the VAS scores, all patients experienced no or mild pain with BI and PDL injections after the application of IANB. Anesthetic success occurred in 81.48% for IANB plus BI (IANB/BI) compared with 83.33% for IANB plus PDL injection (IANB/PDL injection). None of the observed differences between the 2 groups was significant (P > .05). CONCLUSION: Both injection combinations resulted in high anesthetic success in patients with irreversible pulpitis in the mandibular first molar.


Asunto(s)
Anestesia Dental/métodos , Anestesia Local/métodos , Anestésicos Locales/administración & dosificación , Bloqueo Nervioso/métodos , Pulpitis/terapia , Adolescente , Adulto , Carticaína/administración & dosificación , Mejilla , Femenino , Humanos , Inyecciones , Masculino , Mandíbula , Nervio Mandibular , Persona de Mediana Edad , Diente Molar , Dimensión del Dolor , Ligamento Periodontal , Adulto Joven
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