Influence of anatomic reference on the buccal contour of prosthetic crowns

Abstract

During clinical practice, when performing prosthetic rehabilitation with single crowns, improper reproduction of the dental contour by the dental laboratory is a common occurrence. Therefore, the present study evaluated the fidelity of the reproduction of the buccal contour in an upper left canine performed by three Dental Prosthesis Technicians (DPT) using the indirect laminate veneer technique. First, the DPTs confected the veneers based on a model obtained from the upper arch of a dental dummy, containing a replica of an upper left canine with a prosthetic preparation for a laminate veneer. Then, the same DPTs received other identical models, now with the replica of the upper left canine with no preparation, to be used as an anatomical reference for confecting the laminate veneers. The laminate veneers were then bonded to the plaster models and had their buccal contour individually measured. Measurements were also made of the buccal contour of the reference canine. The data were analyzed by ANOVA and the t-test (p = 0.05). Results showed 100% of buccal overcontour when the laminate veneers were compared to the reference canine, regardless of which DPT confected the veneer and regardless of using or not the anatomical reference. The DPTs who participated in the present study were unable to acomplish a faithful anatomical reproduction of the buccal contour, creating an overcontour in all samples. This situation may be responsible for increasing the probability of periodontal and esthetic harm in clinical practice.

Axial Contour Alteration following Restorative Treatment: A Systematic Review

“…Four studies of Group I were clinical and based on actual treated patients [8][9][10][11], and one of them was a laboratory study [12]. From Group II, six studies were human studies [8,11,[13][14][15][16] and three studies were animal studies [5,17,18].…”

“…The increased tooth width, increased emergence angle or greater volume indicated an increase in tooth contour. The implemented contour measurement methods were the dimensional measurement of tooth width [8], surface morphology [10,12], and cross sectional analysis [9,11]. In addition, the relationship between the axial tooth contour alterations and the location on the tooth from the gingival margin was evaluated by some studies [10][11][12].…”

“…Most of the alterations tended to be an increase of the contour [8,[10][11][12]. Only one study reported a reduction of the contour following restorative treatment [9].…”

“…Yotnuengnit et al had found the emergence angle of the restored teeth was likely to be greater than the control teeth [11]. Vasconcelos et al had found that 100% of the teeth had an increase in the contour following restorations [12]. This was the case even when the technicians had access to the reference tooth contour.…”

“…According to Meijering et al the incisal width was more affected from over-contouring while the cervical width is very identical to the original tooth contour [10]. Similarly, Vasconcelos et al had observed a consistent increase of the contour as the distance from the gingival margin increases [12]. On the other hand, Yotnuengnit et al had found the emergence angle was greater for the subginigival profile than the supragingival profile [11].…”