[Clinical evaluation of "All-on-Four" provisional prostheses reinforced with carbon fibers].

OBJECTIVE: To assess the clinical effects of carbon fiber reinforcement on the "All-on-Four" provisional prostheses.

METHODS: Provisional prostheses were divided into control group and carbon fiber reinforcing group according to whether carbon fiber reinforcement was used in the provisional prostheses base resin. In our study, a total of 60 patients (32 males and 28 females) with 71 provisional prostheses(28 maxilla and 43 mandible)were enrolled between April 2008 and December 2012 for control group; a total of 23 patients (13 males and 10 females) with 28 provisional prostheses (9 maxillas and 19 mandibles) were enrolled between January 2013 and March 2014 for carbon fiber reinforcing group. The information of provisional prostheses in the patients was recorded according to preoperative examination. We used the date of definitive prosthesis restoration as the cut-off point, observing whether fracture occurred on the provisional prostheses in the two groups. Additionally we observed whether fiber exposure occurred on the tissue surface of the provisional prostheses and caused mucosal irritation. The interface between the denture base resin and the fibers was examined using scanning electron microscopy (SEM).

RESULTS: The age [(57.3 ± 10.1) years vs.(55.1 ± 11.4) years], gender (32 males and 28 females vs. 13 males and 10 females), maxilla and mandible distributions (28 maxillas and 43 mandibles vs. 9 maxillas and 19 mandibles), the number of extraction jaws (46 vs. 23), the average using time [(7.8 ± 1.3) months vs. (7.5 ± 1.1) months], and the opposing dentition distributions of provisional prostheses of the patients showed no significant differences between the control and reinforcing groups. There were 21(29.6%) fractures that occurred on the 71 provisional prostheses in the control group; there was no fracture that occurred on the 28 provisional prosthesesin the carbon fiber reinforcing group. The fracture rate of the carbon fiber reinforcing group was significantly lower than that of the control group (P=0.001). No carbon fiber exposure and mucosal irritation were observed from clinical examination.SEM revealed relatively continuous contact between the fiber and acrylic resin, and the resin particles adhered on the surface of the carbon fibers.

CONCLUSION: The addition of carbon fibers between abutments placed on "All-on-Four" provisional fixed denture base resin may be clinically effective in preventing "All-on-Four" denture fracture and can provide several advantages for clinical use.