Avaliação da resistência transversa de dentes acrílicos para base de dentaduras

O destacamento de dentes anteriores nas proteses totais superiores ocorre com frequencia. Ultimamente tem surgido no mercado odontologico marcas comerciais de dentes acrilicos sem estudos quanto a resistencia de uniao as bases de proteses. A proposta deste estudo foi verificar a resistencia a forca transversa de 3 marcas comerciais de dentes pre-fabricados em acrilico a uma base de resina termopolimerizavel. Foram utilizados 30 dentes (incisivos centrais superiores), divididos em 3 grupos: A-Ivostar (Ivoclar Vivadent); B- Biotone (Dentsply) e Trilux (Ruthinium). Foi confeccionada uma retencao com ponta esferica na sua base e os mesmos foram unidos a um cilindro de resina acrilica termopolimerizavel cor rosa (Classico), obtidos a partir de tecnica de inclusao de protese total convencional e imersos em agua destilada em estufa a 37o C por 7 dias. Em uma maquina de ensaios Instron (Universal 4301), foram aplicadas forcas crescentes na face lingual, com angulacao de 45o em relacao ao longo eixo do dente, com velocidade de 0,5mm/min, ate a ocorrencia da fratura. Os valores obtidos foram submetidos ao teste estatistico ANOVA (±=0,05) indicando que a tensao media de ruptura difere entre os grupos (F 2;27 = 215,22; p=0,001). O teste de Tukey mostrou diferenca significante na resistencia a forca transversa dos dentes para as 3 marcas, em ordem decrescente (MPa): Ivostar (893,36 ± 56,54), Biotone (593,58 ± 68,11) e Trilux (342,51±52,52). Concluiu-se que ha diferencas estatisticamente significantes na resistencia a forca transversa de dentes pre-fabricados que devem ser levadas em consideracao para a confeccao das proteses. Termos de indexacao : protese parcial removivel; protese total superior; dente artificial. ABSTRACT Detachment of anterior teeth from maxillary dentures is fairly frequent. Lately, several brands of acrylic teeth have been recommended to complete dentures fabrication. However, few studies may be found regarding bond strength between artificial teeth and acrylic bases. The purpose of this research was to quantify bond strength of 3 commercial brands of acrylic resin teeth to heat-cure resin denture base. Each group was composed of 10 teeth (maxillary central incisors) as follows A-Ivostar (Ivoclar Vivadent); B- Biotone (Dentsply) e Trilux (Ruthinium) adding up to 30 samples. All teeth were polished before mechanical retention was performed with round burs at the center of the ridge lap surface. The teeth were adapted to a cylindrical resin base (Classico) obtained from heat-cured conventional polymerization technique. Samples were immersed into distilled water and stored at 37o C (7 days). Compressive test was performed (Instron 4301) applying an increasing load on the palatal surface at 45 degree angle to the long axis of each tooth. Load incidence was applied at a crosshead speed of 0,5mm/min until fracture occurred. Data obtained were submitted to ANOVA (±=0,05) which demonstrated that the mean tension fracture rates were different among the groups (F 2;27 = 215,22; p=0,001). Tukey test verified statistically significant differences on adhesive bond strength of the three commercial brands (MPa): Ivostar (893.36 ± 56.54), Biotone (593.58 ± 68.11) e Trilux (342.51±52.52). It can be concluded that statistical difference observed on adhesive bond strength of artificial teeth to resin bases should be considered prior to complete denture fabrication. Indexing terms : removable partial denture; complete upper denture; artificial tooth.