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). Group V had the highest mean MPa (N/mm2) (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). 3. The pin-retained FPDs showed a high dislodgement resistance compared to the conventional three-unit FPDs (P < .05).

A comparative study of the resistance to dislodgement of fixed prostheses using Bio-pin(R) / 대한치과보철학회지

STATEMENT OF PROBLEM: The current trend in prosthodontics is the adoption of a conservative approach to preparing dental prostheses by minimizing the amount of sound tooth structure removal during preparation. PURPOSE: The major disadvantage of the adhesion bridge is the inherently poor resistance to dislodgement that its use in areas subjected to high occlusal load is limited. The purpose of this study was to compare the dislodgement resistance of Bio-pin(R), conventional 3-unit and adhesion bridges. MATERIAL AND METHODS: The experimental groups were classified as follows: .Group I : 3-unit bridge cemented using Super-Bond. C&B .Group II : Adhesion bridge cemented using Super-Bond. C&B .Group III : Bio-pin(R) design adhesion bridge without incorporation of Bio-pin(R) (cemented using Super-Bond. C&B) .Group IV-1: Bio-pin(R) retained adhesion bridge incorporating a single Bio-pin(R) (cemented using Super-Bond. C&B) .Group IV-2: Bio-pin(R) retained adhesion bridge incorporating a single Bio-pin(R) (cemented using Panavia. F) .Group V : Bio-pin(R) retained adhesion bridge incorporating two Bio-pins. (cemented using Super-Bond. C&B) RESULTS: The results of this study were as follows: 1. Significant differences in dislodgement resistance of the restorations were found between Group I, Group II and Group III (p<0.05). No significant differences in dislodgement resistance of the restorations were observed between Group I, GroupIV-1 and GroupV. However, there were significant differences in dislodgement resistance between GroupII and the other groups (p<0.05). 2. No significant differences in dislodgement resistance of the restorations were observed between GroupIV-1 and GroupIV-2, both of which utilized a single Bio-pin(R). However, significant differences were observed when GroupIII was compared to either GroupIV-1 or GroupV (p<0.05). 3. No significant differences in dislodgement resistance relative to the type of dental cements used were found. CONCLUSION: From the above results, it is concluded that the dislodgement resistance of Biopin. bridge restorations utilizing a single Bio-pin(R) is similar to that of a conventional 3-unit bridge. The results also suggest that Bio-pin(R) bridge restorations using a single Bio-pin(R) are a viable alternative to the conventional 3-unit bridge when minimal removal of sound tooth structure and fulfillment of both function and esthetic aspects are considered.