Resin-bonded fixed partial dentures: a review of three decades of progress

Rehabilitation of Congenitally Missing Bilateral Incisors With the Maryland Bridge: A Case Report

Congenital partial hypodontia is a commonly encountered disorder, presenting a challenge for adolescents seeking treatment, as existing options often come with drawbacks. Among these options, the Maryland Bridge stands out for its accessibility and notable benefits in terms of both strength and aesthetics. This article explores the merits of this treatment modality, supported by a detailed case study demonstrating its successful application. An 18-year-old patient was referred to our hospital with a complaint of missing bilateral maxillary incisors. Upon clinical examination, it became apparent that the orthodontic treatment was done and exhibited the absence of bilateral incisors in the upper arch. Subsequent diagnosis confirmed congenital partial hypodontia. To address the missing teeth, a treatment plan centered around the use of a Maryland Bridge was devised. One of the persistent challenges faced by restorative dentists is devising solutions for congenitally missing lateral incisors. Despite the availability of numerous therapeutic alternatives, none are without their limitations. However, the outcome of the rehabilitation in this case proved to be notably aesthetically pleasing, effectively fulfilling the intended purpose. As a result, this article advocates for the Maryland Bridge as a viable option for patients facing similar dental challenges.

Shape optimization of a 2-unit cantilevered posterior resin-bonded fixed dental prosthesis

STATEMENT OF PROBLEM

The cantilevered resin-bonded fixed dental prosthesis (RBFDP) is a feasible and minimally invasive treatment option to restore a single missing tooth, especially when the missing tooth space is small (<7 mm) and cost-effectiveness is essential. However, its long-term survival needs to be improved by increasing its structural strength and interfacial adhesion.

PURPOSE

The purpose of this study was to improve the interfacial bonding and to enhance the structural strength of a 2-unit inlay-retained cantilevered RBFDP with a 2-step numerical shape optimization.

MATERIAL AND METHODS

A finite element model of a mandibular first molar with a second premolar pontic was constructed. A load of 200 N simulating the average occlusal force was applied on the mesial fossa of the pontic. In the first step, an in-house user-defined material subroutine was used to generate the cavity preparation. The subroutine iteratively changed the tooth tissues next to the pontic to composite resin according to the local stresses until convergence was achieved. In the second step, the subroutine was used to optimize the placement of fibers in the pontic by placing fibers in high-stress regions. To assess the debonding resistance and load capacity of the optimized and conventional designs, further analyses were conducted to compare their stresses at the tooth-restoration interface and those within the restoration.

RESULTS

Shape optimization resulted in a shovel-shaped cavity preparation and a pontic with fibers placed near the occlusal surface of the connector region. With the optimized cavity preparation only, the maximum principal stress within the restoration and the tooth structure was reduced from 639.4 MPa to 525.4 MPa and from 381.7 MPa to 352.8 MPa, respectively. With the embedded fibers, the shovel-shaped cavity preparation reduced the maximum interfacial tensile stress by approximately 70% (conventional: 189.6 MPa versus optimized: 57.0 MPa) and the peak maximum principal stress of the veneering composite resin by 45% (conventional: 638.8 MPa versus optimized: 356.5 MPa). The peak maximum principal stress was also reduced for the remaining tooth structure by approximately 30% (conventional: 372.2 MPa versus optimized: 253.1 MPa).

CONCLUSIONS

Shape optimization determined that a shovel-shaped retainer with fibers placed near the occlusal surface of the connector area can collectively reduce the interfacial and structural stresses of the 2-unit cantilevered fiber-reinforced RBFDP. This may offer a more conservative treatment option for replacing a single missing tooth.

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.

The Maryland bridge retainer: A modification of a Maryland bridge

Preservation of the maxillary lateral incisor space after orthodontic treatment in an adolescent patient traditionally requires the use of a retainer with a lateral pontic, commonly referred to as a "flipper," which is minimally effective in the long term. This article illustrates a technique for chairside fabrication of a Maryland bridge retainer for semi-permanent retention. A stainless steel braided palatal wire is bonded to the anterior teeth. A pontic is then built intraorally with flowable composite, using the palatal wire as scaffolding. The retainer is maintained until the patient is of age for a more permanent restoration.

Modified PEEK Resin Bonded Fixed Dental Prosthesis for a Young Cleft Lip and Palate Patient

OBJECTIVE

This clinical report presents the use of a modified poly ether-ether ketone material as an alternative material for the fabrication of resin-bonded fixed dental prosthesis (RBFDP) framework. This new material can be used for patients allergic to metals, maintaining the same high esthetic demand of ceramics, presenting light weightness and a flexibility similar to bone as a distinct advantage over ceramic materials.

CONCLUSIONS

The use of a BioHPP RBFDP framework could be considered as an alternative restoration for the replacement of missing lateral incisors in young patients with cleft palate defects.

CLINICAL SIGNIFICANCE

This modified PEEK material known as BioHPP, is a biocompatible, non allergic, rigid material with good mechanical properties, wear resistance, chemical stability, high polishing and low absorption properties. BioHPP frameworks can be manufactured either via CAD/CAM or via the conventional lost wax technique. The low modulus of elasticity, combined with the use of indirect composite resin as a veneering material, provide a distinct advantage over ceramics or metal ceramics on dampening the occlusal forces, reducing the risk of debonding. (J Esthet Restor Dent 28:201-207, 2016).

Restoring Congenitally Missing Maxillary Lateral Incisors Using Zirconia-Based Resin Bonded Prostheses

OBJECTIVE

This clinical report describes an alternative treatment modality for the replacement of congenitally missing maxillary lateral incisors in a 17-year-old patient.

CLINICAL CONSIDERATIONS

Zirconia-based resin-bonded fixed partial dentures (RBFPDs) were selected as a viable and conservative treatment option in a young individual with highly aesthetic expectations. Fabrication of all-ceramic RBFPDs followed specific preparation design and features to accommodate two retainers. The zirconia frameworks with bilateral wings were digitally designed and then milled by a computer-aided design and computer-aided manufacturing (CAD/CAM)-controlled milling machine. Zirconia surface was treated with a two-step chairside tribochemical silica-coating/silane coupling surface treatment protocol, and adhesive resin luting cement was used to achieve micromechanical and chemical bonding. Completion of the treatment resulted in a functional and aesthetic successful outcome and a 17-month follow-up presented uneventful.

CONCLUSION

Contemporary adhesive techniques involving resin-bonded zirconia-based prostheses can be utilized successfully and predictably in young patients with single missing teeth when implant therapy is currently not a treatment of choice and a less invasive approach is desired.

CLINICAL SIGNIFICANCE

The zirconia-based resin-bonded prosthesis constitutes a viable and conservative treatment modality for the replacement of missing teeth either congenitally or from another etiology in young patients in which implant therapy and a fixed partial denture are currently contraindicated.

Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report

Key Clinical Message

This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient.

Multi-factorial retainer design analysis of posterior resin-bonded fixed partial dentures: a finite element study

OBJECTIVES

Biomechanical aspects related to prosthesis design of RBFPD have been proposed as the predominant contributor to unpredictable clinical retention. The aim of this study was to investigate the biomechanics of multiple posterior retainer designs and their interactions using three-dimensional finite element analysis.

METHODS

To understand the interactions among the retainer design factors, three values of retainer thicknesses (1.2, 0.8 and 0.4mm), heights (100, 75 and 50% of the distance from 2mm above the CEJ to the occlusal surface) and angle of the axial surface extensions (150, 180 and 210 degrees ) were selected as the design parameters. Twenty-seven RBFPD FE models with three retainer-design parameters were created by image processing, contour stacking, and mapping mesh procedures. The maximum principal and von Mises stresses in remaining tooth and prosthesis, respectively, were recorded in 54 FE analyses (27 FE models with axial and lateral occlusal loadings).

RESULTS

The simulated results showed that the averaged stress values of the remaining tooth and prosthesis decreased with greater retainer thickness and height as a result of increasing prosthesis stiffness and maximizing of the bonding area between the enamel and the retainer, respectively. However, no significant stress differences were found according to the angle of the retainer extension because stress transmission was concentrated at the connectors.

CONCLUSIONS

The stress elevation rate (termed as VSR-stress elevation by decreasing one unit volume of the remaining tooth) addresses that the height was the most influential factor for the remaining tooth structure, followed by retainer thickness and extension angle.

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.

Effect of thione primers on bonding of noble metal alloys with an adhesive resin

OBJECTIVES

The purpose of the current study was to evaluate the effects of two metal conditioners on the bond durability of an adhesive resin joined to noble metal alloys by comparing pre- and post-thermocycling bond strengths.

METHODS

Two different sizes of disk specimens (10 and 8mm in diameter by 2.5mm thickness) were prepared from silver-indium (Ag-In-Zn, Salivan), silver-palladium-copper-gold (Ag-Pd-Cu, Castwell M.C.12), metal-ceramic gold (Au-Pt-Pd, Degudent-Universal), metal-ceramic palladium (Pd-Ga-Co, PTM 88), type IV gold (type IV, Casting Gold) alloys, and pure silver (pure Ag). The specimens were air-abraded with 50-microm grain sized alumina, conditioned either with a thiouracil primer (Metaltite) or with a thione-phosphate primer (Alloy Primer), then bonded with an adhesive resin (Super-Bond Opaque). Shear bond strengths were determined both before and after repeated thermocycling (4 degrees C and 60 degrees C, 1min each, 100, 000cycles). The results were compared by analysis of variance and post-hoc multiple comparison intervals.

RESULTS

The average post-thermocycling bond strengths in MPa (n=8) generated with the thiouracil primed and thione-phosphate primed groups, respectively, were: 3.4 and 5.8 for the Ag-In-Zn alloy, 40.4 and 37.7 for the Ag-Pd-Cu alloy, 26.4 and 33.5 for the Au-Pt-Pd alloy, 27.4 and 36.6 for the Pd-Ga-Co alloy, 40.2 and 40.3 for the type IV alloy, and 37.3 and 32.4 for the pure Ag. The Ag-In-Zn alloy exhibited significantly lower bond strength than the other alloys, whereas the Ag-Pd-Cu and type IV alloys exhibited the greatest magnitude of bond strength for both primers (p<0.05).

CONCLUSIONS

It can be concluded that the combined use of either of the two thione primers and the adhesive resin is effective for bonding the metal/alloys examined, with the exception of the Ag-In-Zn alloy.

Comparison of resin-bonded prosthesis groove parallelism with the use of four tooth preparation methods

STATEMENT OF PROBLEM

A precise preparation is required to develop resistance form resulting in mechanical stability of the framework for resin-bonded prostheses (RBPs).

PURPOSE

The effects of 4 methods of tooth preparation (freehand, guiding pin, extraoral parallelometer, and intraoral parallelometer) on the deviation of proximal grooves from a preestablished path of insertion (guide planes) were investigated under clinical conditions.

MATERIAL AND METHODS

Tooth preparation of proximal grooves was performed by 32 dentists on resin substitutes of posterior segments intraorally with a single test patient. A Latin-square randomized cross-over design was selected as the experimental design.

RESULTS

The significant least angular deviation of proximal grooves from path of insertion was achieved with an intraoral parallelometer (mean +/- SD 3.15 +/- 1.67 degrees). Compared with freehand tooth preparations (4.37 +/- 2. 11 degrees), neither use of a guiding pin (4.10 +/- 1.62 degrees) nor an extraoral parallelometer (5.06 +/- 2.33 degrees) improved the results.

CONCLUSION

Divergence of guiding grooves from path of insertion was reduced with the use of an intra-oral parallelometer. This should improve mechanical stability of posterior RBPs.

The effect of tin-electroplating on the bond of four dental alloys to resin cement: an in vitro study

STATEMENT OF THE PROBLEM

Nickel-chromium alloys are indicated for the construction of resin-bonded fixed partial dentures; however, the potential toxicity of nickel has been a source of concern. Composite cements do not develop an adequate bond to air abraded noble alloys, which cannot be electrolytically etched. Tin-electroplating of noble alloys appears to be an alternative treatment for resin bonding.

PURPOSE

This in vitro study investigated the effect of tin-electroplating on the bond of a composite cement to base and noble alloys.

MATERIAL AND METHODS

Tensile tests were made with disks of four alloys that were cemented to each other with an adhesive composite cement after (1) air abrasion with 50 microns aluminum oxide and (2) air abrasion plus tin-electroplating.

RESULTS

Tin-electroplating increased the bond strength of metal-ceramic gold alloy (Au,Pd,Pt) to a level comparable to the nickel-chromium alloy, but had a harmful effect on type IV gold alloy.

CONCLUSIONS

Despite the recommendation for tin-electroplating of type IV gold alloys, this procedure did not improve bond strength to composite in this study.

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

A uncomplicated clinical procedure to enhance the retention of posterior resin-bonded fixed partial dentures was described. This method involves some modifications to the preparation and casting design and requires slightly more time and attention at the cementation stage of the prosthetic treatment.