RESUMEN
BACKGROUND: Information on fracture biomechanics has implications in materials research and clinical practice. The aim of this study was to analyse the influence of non-carious cervical lesion (NCCL) size, restorative status and direction of occlusal loading on the biomechanical behaviour of mandibular premolars, using finite element analysis (FEA), strain gauge tests and fracture resistance tests. METHODS: Ten buccal cusps were loaded on the outer and inner slopes to calculate the strain generated cervically. Data were collected for healthy teeth at baseline and progressively at three lesion depths (0.5 mm, 1.0 mm and 1.5 mm), followed by restoration with resin composite. The magnitude and distribution of von Mises stress and maximum principal stress were simulated at all stages using FEA, and fracture strength was also determined (n = 7 per group). RESULTS: There were significant effects of the lesion size and loading directions on stress, strain and fracture resistance (p < 0.05). Fracture resistance values decreased with increase in lesion size, but returned to baseline with restorations. CONCLUSIONS: Combined assessment of computer-based and experimental techniques provide an holistic approach to characterize the biomechanical behaviour of teeth with both unrestored and restored NCCLs.
Asunto(s)
Diente Premolar/fisiología , Mandíbula , Cuello del Diente/fisiología , Fracturas de los Dientes/cirugía , Adulto , Fenómenos Biomecánicos , Resinas Compuestas , Restauración Dental Permanente/métodos , Análisis del Estrés Dental/métodos , Análisis de Elementos Finitos , HumanosRESUMEN
BACKGROUND: The aim of this study was to measure the effect of simulating two different loads on maxillary incisors displaying eight morphological types of non-carious cervical lesions, unrestored and restored with an adhesive restoration, by quantifying the stress distributions generated using finite element analysis. METHODS: Virtual models of maxillary incisors were generated using the CAD software (RhinoCeros). After composing virtual dental and supporting structures with and without non-carious cervical lesions, each model was meshed using a control mesh device (ANSYS Finite Element Analysis Software). All of the virtual models were subjected to two load types, oblique load and vertical load, to simulate occlusal forces of 100 N each. Comparisons were made between simulated teeth with non-carious cervical lesions, with and without composite resin restorations, and a simulated sound tooth. Data summarizing the stress distributions were obtained in MPa using von Mises criteria. RESULTS: Oblique loading on simulated non-carious cervical lesions resulted in greater stress concentration compared with vertical loading, and non-carious cervical lesions with acute angles displayed higher stress concentrations at the depth of the lesion. Restoring the lesions with an adhesive restoration, such as composite resin, appeared to overcome this stress concentration. CONCLUSIONS: Restoring NCCLs with adhesive restorative materials, such as a nanohybrid composite resin, appears to recover the biomechanical behaviour similar to sound teeth.
Asunto(s)
Fuerza de la Mordida , Análisis del Estrés Dental/métodos , Incisivo/fisiopatología , Abrasión de los Dientes/fisiopatología , Cuello del Diente , Fenómenos Biomecánicos/fisiología , Resinas Compuestas/uso terapéutico , Materiales Dentales/uso terapéutico , Análisis de Elementos Finitos , Humanos , Maxilar , Resistencia a la Tracción , Abrasión de los Dientes/patología , Abrasión de los Dientes/terapiaAsunto(s)
Síndrome de Down , Diente Primario/anatomía & histología , Diente/anatomía & histología , Adolescente , Niño , Femenino , Humanos , Masculino , OdontometríaRESUMEN
El propósito de este trabajo consiste en describir la naturaleza y frecuencia de las variantes morfológicas de las coronas en la dentición de pacientes con el Síndrome de Down. Dieciocho variantes fueron registradas en la dentición temporaria y permanente en los 147 pacientes con el Síndroem de Down y 47 en los retardados que no presentaban el Síndrome de Down. Estos casos fueron comparados con 250 pacientes normales que sirvieron de controles en el estudio. Para los casos de pacientes con el Síndrome de Down el 90% mostró al menos una variante en la corona y el 47% mostró tres o más. Para los casos de retardados sin el Síndrome de Down el 74% registró al menos una variante y el 13% o tres o más. Para el grupo control el 24% mostró al menos una variación de solamente un 1% mostrando más de tres. Las variantes más comunes de las coronas de los pacientes con el Síndrome de Down correspondieron a las superficies labiales de los dientes, anteriores y bordes incisales; alteraciones de las cúspides inclinadas de los caninos; falta o reducción distolingual de las cúspides de los molares maxilares y desplazamiento distal de las cúspides de los molares mandibulares
Asunto(s)
Niño , Adolescente , Humanos , Masculino , Femenino , Anomalías Dentarias/complicaciones , Coronas/métodos , Síndrome de Down/complicacionesAsunto(s)
Diente Molar/anatomía & histología , Niño , República Dominicana , Femenino , Humanos , Masculino , OdontometríaAsunto(s)
Diente Primario/anatomía & histología , Población Negra , Preescolar , República Dominicana , Etnicidad , Femenino , Humanos , Masculino , Odontometría , Población BlancaRESUMEN
An assessment of deciduous tooth-size asymmetry showed no evidence of sex differences. When asymmetry was compared between the various tooth dimensions, the buccolingual dimensions of mandibular incisors consistently displayed high asymmetry values. This finding may reflect a developmental interaction between the deciduous incisor tooth germs and their lingually-placed permanent successors.