Posterior resin-bonded fixed partial denture with a modified retentive design: a clinical report

Bond Strength Evaluation of Inlay-Retained Resin-Bonded Fixed Partial Dentures with Two Different Cavity Designs and Two Different Adhesive Systems: In Vitro Study

Background/Aim: The purpose of this in-vitro study was to compare the resin-bonded fixed partial dentures (RBFPD) fabricated using two different structural designs and two different antibacterial adhesive lutting protocols in regard to their resistance to debonding.

Material and Methods: Forty samples for a model with single missing molar were divided into 4 groups (M1, M2, C1, C2) (n=10). M1 and M2 were prepared in accordance with modified inlay slot-cavity retained RBFPD design; C1 and C2 were prepared according to conventional inlay slot-cavity retained RBFPD design. M1 and C1 cavities were treated with 2% chlorhexidine-based (CHX) cavity disinfectant and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) containing adhesive system; M2 and C2 cavities were treated with MDP and 12-methacryloyloxydodecylpyridinium bromide (MDPB) containing adhesive system featuring antibacterial cavity cleansing effect. The RBFPDs were made of base-metal alloy and their fit surfaces sandblasted with aluminium oxide (Al2O3). Adhesive resin cement was used for cementation, and the RBFPD retainers were interlocked into their corresponding inlay cavities using composite resin. After 1 week being immersed in aqueous environment, the RBFPDs were subjected to tensile loading at a crosshead speed of 1 mm/min until failure. One way ANOVA and Tukey HSD tests were used for statistical evaluation (α=0.05). Mode of failure and tooth damage was also noted.

Results: Mean tensile bond strength values were 356 N for M1, 305 N for M2, 467 N for C1, and 455 N for C2. Tensile strength values of C1 and C2 were significantly higher than those of M1 and M2 (p<0.05). The mode of failure was mostly adhesive in character at the metal-cement interface in all groups. Tooth fracture was observed nearly in all specimens. No significant difference was detected between the antibacterial adhesive lutting protocols (p>0.05).

Conclusions: The RBFPDs with the conventional design were found to be more retentive than those with the modified design. Using an adhesive system featuring antibacterial properties with no need of separate antibacterial agent application during bonding may be favourable.

Fracture resistance of three ceramic inlay-retained fixed partial denture designs. An in vitro comparative study

PURPOSE

The fracture resistance of ceramic inlay-retained fixed partial dentures (CIRFPDs) was studied.

MATERIALS AND METHODS

Thirty CIRFPDs were constructed using ice zircon milled ceramic material. Specimens were divided into three groups, 10 specimens each, according to the abutment preparation: inlay-shaped (occluso-proximal inlay + proximal box), tub-shaped (occluso-proximal inlay), and proximal box-shaped preparations. Each group was then subdivided into two subgroups of five specimens each, according to the span of the edentulous area representing a missing premolar or molar. All specimens were subjected to a fracture resistance test.

RESULTS

CIRFPDs with inlay-shaped retainers showed the highest fracture resistance values for missing premolars and molars. CIRFPDs with box-shaped retainers showed lower fracture resistance values. Statistical analysis revealed a significant difference between the three tested CIRFPD designs. There was a statistically significant difference between CIRFPDs constructed for the replacement of molars and those constructed for the replacement of premolars. The CIRFPD constructed for the replacement of molars gave lower fracture resistance values with the three tested designs. All the fracture resistance values obtained in this study were superior to the assumed maximum mastication forces. Failure mode was delamination and chipping of the veneering material.

CONCLUSIONS

There was a statistically significant difference between the three designs of CIRPFDs tested. There was a statistically significant difference between CIRFPDs constructed for the replacement of molars than those constructed for the replacement of premolars. The CIRFPDs constructed for the replacement of molars gave lower fracture resistance values with the three tested designs. All fracture resistance values obtained in this study were superior to the assumed maximum mastication forces.

Dislodgement resistance of modified resin-bonded fixed partial dentures utilizing tooth undercuts: an in vitro study

STATEMENT OF PROBLEM

Over the years, resin-bonded fixed partial dentures (RBFPDs) have gone through substantial development and refinement. Several studies examined the biomechanics of tooth preparation and framework design in relation to the success rate of RBFPDs and considered retention and resistance form essential for increase of clinical retention. However, these criteria required preparations to be more invasive, which violates not only the original intentions of the RBFPD, but may also have an adverse effect on retention due to loss of enamel, an important factor in bonding.

PURPOSE

The object of this in vitro study was to compare the dislodgement resistance of the new types of RBFPDs, the conventional three-unit fixed partial denture, and conventional design of RBFPD (Maryland bridge).

MATERIAL AND METHODS

Fifty resin mandibular left second premolars and second molars were prepared on dentiforms, according to the RBFPD design. After model fabrication (five group, n = 10), prostheses were fabricated and cemented with zinc phosphate cement. After cementation, the specimens were subjected to tensile loading at a cross head speed of 4 mm/min in a universal testing machine. The separation load was recorded and analyzed statistically using one-way analysis of variance followed by Duncan's multiple range test.

RESULTS

Group V, the pin-retained RBFPDs, had the highest mean dislodgement resistance, whereas specimens of group II, the conventional RBFPDs, exhibited a significantly lower mean dislodgement resistance compared to the other 4 groups (P < .05). There were no significant differences between group I, III, and IV in terms of dislodgement resistance (P > .05). Group V had the highest mean MPa (N/mm(2)) (P < .05). There was no significant difference between groups I, II, III and IV (P > .05).

CONCLUSION

Within the limits of the design of this in vitro study, it was concluded that: 1. The modified RBFPDs which utilizes the original tooth undercuts and requires no tooth preparation, compared with the conventional design of RBFPDs, has significantly high dislodgement resistance (P < .05). 2. The modified RBFPDs which utilizes the original tooth undercuts and requires minimal tooth preparation, compared with the conventional FPDs, has significantly no difference in retention and dislodgement resistance)(P > .05). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P < .05).

In vitro fracture resistance of posterior metal-ceramic and all-ceramic inlay-retained resin-bonded fixed partial dentures

STATEMENT OF PROBLEM

Inlay-retained resin-bonded fixed partial dentures (RBFPDs) are conservative prosthetic restorations; however, their resistance to fracture is not clear.

PURPOSE

The purpose of this study was to compare fracture loads of posterior complete coverage metal-ceramic restorations with all-ceramic inlay-retained RBFPDs.

MATERIAL AND METHODS

Thirty-two posterior ceramic RBFPD restorations were divided into 4 groups (n=8): (1) Complete metal-ceramic fixed partial dentures (MC-FPDs) fabricated of Ni-Cr-based alloy (Wirolloy) and veneered with a ceramic (IPS d.SIGN) as the control group; (2) inlay-retained metal-ceramic (MC RBFPDs) with the same materials as the control; (3) inlay-retained lithium disilicate (LD) glass-ceramic (IPS Empress 2) RBFPDs; and (4) inlay-retained zirconia-based (Z) ceramic (Cercon) RBFPDs. Control specimens were prepared to receive conventional complete MC-FPDs designed to include a 1.3-mm-circumferential, 90-degree flat shoulder with rounded angles. Inlay-retained RBFPD specimens were prepared with 2-mm occlusal reduction but without bevels at the occlusal or gingival margins. Specimens were loaded and fracture loads (N) measured at fracture with a universal testing machine at a crosshead speed of 1.0 mm/min and 250 kgf load cell. Data were analyzed with 1-way ANOVA and Duncan test (alpha=.001).

RESULTS

Fracture loads (mean +/- SD) were greatest for control specimens (1318.43 +/- 211.00 N) and Z-RBFPD (1247.70 +/- 262.51 N) specimens as compared to MC-RBFPD or LD-RBFPD (P < .001). MC-RBFPD exhibited the next highest fracture loads (958.01 +/- 194.29 N), and LD-RBFPD exhibited the significantly lowest values (303.23 +/- 92.54 N) of the materials tested (P < .001).

CONCLUSION

Inlay-retained zirconia-based ceramic RBFPDs demonstrated the greatest fracture resistance among all inlay-retained restorations tested.