Appraisal of the convergence angle of full crown preparations

Abstract

The level of coning had as ideal in preps for fixed total crowns is that one that provides to greater retention of the restoration. Literature recommends a variation around 2º to 6º, however these values hardly are gotten in practical the clinic, being if showing frequent superior to the recommended angulation; however, bigger coning can be acceptable, since each tooth has supported has characteristics and proper necessities for retention. The objective of this study was to measurer the coning of the preps for total crowns carried through by the students of Fixed I Prosthesis Discipline of the course of Dentistry, from its angle of convergence. A total of 64 resin teeth were selected for dummy, prepared in the period from 2005 to 2006. This body-of-test had been grouped in accordance with the arc and the dental group: G1- teeth anterosuperiors (n = 36); G2 - teeth anteroinferiors (n = 2); G3 - superior premolars (n = 7); G4-inferior premolars (n = 4); G5 - superior molars (n = 2) and G6 - inferior molars (n = 13). By the AutoCAD 2006 Program, the images had been captured with a video camera CCD connected to a stereoscopic, the angle of convergence in palatal vestibulelingual(VL/P), how much mesiodistal (MD) directions were measured. The data were submitted to a variance analysis (p = 0,05). The G2 was the group that presented the minor averages of coning in direction VL/P (6,50º, p < 0,05) and the G1 presented the higher averages in direction MD (44,18º, p < 0,05). It concluded that the averages of the angles of convergence in the present study had been higher that the praised ones in literature.