RESUMEN
OBJECTIVE: We investigated whether there is a correlation between the buccolingual crown diameter and cusp tip distance and if that can be considered a factor influencing the formation of a transversal malocclusion. MATERIALS AND METHODS: The buccolingual crown diameters and cusp tip distances of all premolars and first molars of 102 normal dentitions and 123 dentitions with a transverse malocclusion were measured and examined for significant differences. We also investigated whether there were differences in size between the genders and between left and right sides. RESULTS: General differences in buccolingual crown diameters ranged from 0.3 mm to 0.6 mm, and in cusp tip distance from 0.4 mm to 0.7 mm. Buccolingual crown width was generally greater in boys than girls, whereas we observed no statistically significant difference in cusp tip distances. Comparison of left and right sides revealed no significant difference. We were able to statistically prove the correlation between buccolingual tooth diameter and cusp tip distance. CONCLUSIONS: The results suggest that larger teeth with a greater cusp tip distance offer a more favorable prerequisite for the appearance of regular transversal occlusal relations than those with a smaller distance. The buccolingual crown width and its corresponding cusp tip distance seem important for initial contact with the antagonists, and may be regarded as a factor that determines whether or not a crossbite develops.
Asunto(s)
Maloclusión/etiología , Corona del Diente/anatomía & histología , Adolescente , Diente Premolar/anatomía & histología , Niño , Femenino , Humanos , Masculino , Diente Molar/anatomía & histología , Factores de Riesgo , Factores Sexuales , Estadística como AsuntoRESUMEN
Bonded lingual retainers (individually adjusted multistranded wires with one bond site per tooth) are used extensively to maintain the orthodontic treatment result. Failure or loss often leads to a relapse. The bond strength of bonded lingual retainers has not yet been studied in respect of the loads that can be withstood by them through deflection of the interdental archwire region. Furthermore, human anterior teeth have never before been used for a study of this kind. Six different wire/composite combinations were studied (wires: Dentaflex co-axial 0.018", Dentaflex multistranded 0.018", and Respond Dead Soft straight, length 0.0175"; composites: Tetric Flow and Heliosit Orthodontic) by bonding 1 cm lengths of wire to the lingual surfaces of 360 extracted lower anterior teeth. Using an Instron 6025 universal testing machine, vertical shear bond strength tests at the bond site as well as vertical shear bond strength tests and horizontal tensile strength tests were performed. The failure characteristics after failure at maximum force were evaluated by light microscopy, scanning electron microscopy, and morphometry. Most failures were observed at the enamel/composite interface. The selected wires displayed no significant differences; Tetric Flow proved to be the most stable resin; and no enamel tear-outs were observed.