Predictable resin-bonded bridges in general dental practice

Practical advice for successful clinical treatment with resin-bonded bridges

Resin-bonded bridges are one of the main options for replacing missing teeth for hypodontia patients. This technique offers several advantages for these patients, who are often young, have unrestored abutment teeth, and have had tooth positions optimised by orthodontic treatment. However, the replacement of missing teeth can be challenging due to tooth positions and anomalies of abutment tooth shape and size.These patients are often young adults at the time of restoration, making the minimally invasive nature and predictable long-term success of resin-bonded bridges advantageous over other treatment methods.This paper in the hypodontia themed issue discusses the importance of case selection and gives practical advice for the design and provision of resin-bonded bridges.

Validation of a shape-optimized 2-unit cantilevered inlay-retained fiber-reinforced resin-bonded dental prosthesis

STATEMENT OF PROBLEM

Current designs of fiber-reinforced composite (FRC) resin-bonded fixed dental prostheses (RBFDPs) have a limited lifespan, failing mainly through veneer-fiber delamination, debonding, and fracture.

PURPOSE

The purpose of this in vitro study was to validate a new inlay-retained 2-unit cantilevered RBFDP with an optimized cavity and fiber layout proposed in a previous study by using simulated occlusal loading.

MATERIAL AND METHODS

Two groups of specimens (n=20), 1 with and 1 without glass fibers, were used to test the influence of the cavity design and that of the fiber layout on their load capacity, respectively. The specimens without fibers were directly cut from a resin-ceramic block by using a computer-aided manufacturing system, while those with fibers were manually fabricated with unidirectional glass fibers and composite resin in a silicone mold. The specimens with and without fibers were attached to abutments made of the same resin-ceramic with a cyanoacrylate-based adhesive and a resin-based dental cement, respectively. An increasing compressive load was applied on the mesial fossa of the premolar pontic until failure. Cracking in the specimens during loading was monitored with a 2-channel acoustic emission (AE) system.

RESULTS

All the specimens without fiber reinforcement debonded from the abutments. Those using the optimized shovel-shaped cavity design had a mean ±standard deviation failure load (50.0 ±17.3 N) that was 193% higher than that of those with the conventional step-box design (17.1 ±6.2 N; P<.001). No significant difference was found between the groups for the mean number of AE events per specimen (step-box: 49 ±34 versus shovel-shaped: 63 ±34; P=.427), the mean amplitude of each event (58.4 ±1.3 dB versus 59.5 ±2.4 dB; P=.299), or the mean time to failure (283.2 ±122.3 seconds versus 297.5 ±66.7 seconds; P=.798). Between the groups of specimens with reinforcing fibers, the mean failure load of the conventional design was approximately half that of the optimized one. Again, no significant difference was found for the mean number of AE events per specimen (conventional: 28 ±18 versus optimized: 52 ±53; P=.248) or the mean amplitude for each AE event (64.9 ±4.2 dB versus 61.7 ±5.2 dB; P=.187). The connectors of 8 fiber-reinforced specimens with the conventional design fractured; the other 2 debonded from the abutments. Half of the shape-optimized fiber-reinforced specimens had fractured abutments, but the cantilevers remained intact, 4 specimens fractured at the connector, and only 1 debonded from its abutment.

CONCLUSIONS

The shape-optimized 2-unit cantilevered FRC RBFDP had a higher load capacity than the conventional design.

Resin bonded bridges in patients with hypodontia: Clinical performance over a 7 year observation period

PURPOSE

Resin bonded bridges (RBBs) are considered a conservative option in the management of hypodontia. This study targeted to analyze the survival of resin bonded bridges provided to patients with Hypodontia by staff and students at the Department of Restorative Dentistry, University Dental School and Hospital Cork, Ireland. It was also to determine the factors that may influence the survival of RBBs in patients with hypodontia.

METHODS

Forty patients with hypodontia who received 65 RBBs from 2001 to 2007 were identified and contacted to be recruited for this study. Of these, nine were not contactable, and five failed to attend. Accordingly, 26 patients (65%) participated in the study, with a total of 51 RBBs.

RESULTS

Of the 51 RBBs evaluated, 44 (86%) were still in situ and functional and 7 (14%) failed. The main reason for failure was repeated debonding. The effect of age, gender, the grade of operator and experience, bridge location, design of the bridge, span length and moisture control during cementation, could not be demonstrated.

CONCLUSION

The effect of age, gender, the grade of operator and experience, bridge location, design of the bridge, span length and moister control on RBB survival could not be demonstrated. Majority of patients with hypodontia showed satisfaction with resin bonded bridges. In replacing congenitally missing teeth in patients with hypodontia, resin-bonded bridges would be an acceptable treatment option.

The effect of resin cement type and cleaning method on the shear bond strength of resin cements for recementing restorations

PURPOSE

This laboratory study assessed the effect of different dentin cleaning procedures on shear bond strength of resin cements for recementing prosthesis.

MATERIALS AND METHODS

4 × 4 flat surface was prepared on the labial surface of 52 maxillary central incisors. Metal frames (4 × 4 × 1.5 mm) were cast with nickel-chromium alloy. All specimens were randomly divided into 2 groups to be cemented with either Panavia F2.0 (P) or RelyX Ultimate (U) cement. The initial shear bond strength was recorded by Universal Testing Machine at a crosshead speed of 0.5 mm/min. Debonded specimens were randomly allocated into 2 subgroups (n = 13) according to the dentin cleaning procedures for recementation. The residual cement on bonded dentin surfaces was eliminated with either pumice slurry (p) or tungsten carbide bur (c). The restorations were rebonded with the same cement and were subjected to shear test. Data failed the normality test (P < .05), thus were analyzed with Mann Whitney U-test, Wilcoxon signed rank test, and two-way ANOVA after logarithmic transformation (α = .05).

RESULTS

The initial shear bond strength of group P was significantly higher than group U (P = .001). Pc and Uc groups presented higher bond strength after recementation compared to the initial bond strength. However, it was significant only in Pc group (P = .034).

CONCLUSION

The specimens recemented with Panavia F2.0 provided higher bond strength than RelyX Ultimate cement. Moreover, a tungsten carbide bur was a more efficient method in removing the residual resin cement and increased the bond strength of Panavia F2.0 cement after recementation.

Longevity of resin-bonded fixed partial dental prostheses made with metal alloys

Objectives

The purpose of this study was to evaluate the clinical performance of resin-bonded fixed partial dental prostheses (RBFPDPs) made with metal alloys.

Materials and methods

The retention of 311 RBFPDPs from 226 patients fabricated from 1983 to 2013 using an adhesive resin was clinically evaluated. Partial or complete debonding of the RBFPDP or framework fracture was considered a treatment failure. All data were obtained from clinical examinations, and missing data were censored at the date of the last available information. The effect of the following factors on survival rate were investigated: patient gender, location (maxilla/mandible and anterior/posterior), number of missing teeth, number of abutment teeth, framework structure, type of metal alloy, patient age at the point of cementation, cement type, and distinction of the treating dentist. Data were analyzed with the Kaplan–Meier survival tests, log-rank tests, and Cox regression analyses (α = 0.05).

Results

The Kaplan–Meier survival rate was 41.2 % ± 6.5 % (standard error) at 28.8 years (last outcome event). Significant differences were found for patient age and treating dentist (p < 0.05). The risk of failure in younger patients was 1.7 times greater than that in older patients and that of inexperienced dentists was 2.0 times greater than that of dentist experienced and specialized in adhesive dentistry.

Conclusions

When fabricating RBFPDPs for younger patients, mechanical preparation for bonding may be necessary in consideration of the risk for debonding. Experienced dentists may achieve better results.

Clinical relevance

Mastery of skills is necessary to ensure excellent prognoses for RBFPDPs.

A review of the success and failure characteristics of resin-bonded bridges

OBJECTIVES

This literature review was designed to assess and compare the success rates and modes of failure of metal-framed, fibre-reinforced composite and all-ceramic resin-bonded bridges.

MATERIALS AND METHOD

A Medline search (Ovid), supplemented by hand searching, was conducted to identify prospective and retrospective cohort studies on different resin-bonded bridges within the last 16 years. A total of 49 studies met the pre-set inclusion criteria. Success rates of 25 studies on metal-framed, 17 studies on fibre-reinforced composite and 7 studies on all-ceramic resin-bonded bridges were analysed and characteristics of failures were identified.

RESULTS

The analysis of the studies indicated an estimation of annual failure rates per year to be 4.6% (±1.3%, 95% CI) for metal-framed, 4.1% (±2.1%, 95% CI) for fibre-reinforced and 11.7% (±1.8%, 95% CI) for all-ceramic resin-bonded bridges. The most frequent complications were: debonding for metal-framed, resin-bonded bridges (93% of all failures); delamination of the composite veneering material for the fibre-reinforced bridges (41%) and fracture of the framework for the all-ceramic bridges (57%).

CONCLUSIONS

All types of resin-bonded bridges provide an effective short- to medium-term option, with all-ceramic performing least well and having the least favourable mode of failure. The methods of failures were different for different bridges with metal frameworks performing the best over time.

Survival of resin-bonded bridgework provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors

OBJECTIVE

To analyse the clinical performance and factors influencing the survival of resin-bonded bridgework provided for hypodontia patients with missing maxillary lateral incisors, following orthodontic treatment to open, maintain or redistribute the missing tooth space.

DESIGN

A retrospective analysis of patients treated at a single centre using case notes with all patients invited for review to corroborate findings.

SETTING

Departments of Orthodontics, Child Dental Health and Restorative Dentistry, Newcastle upon Tyne Dental Hospital and School.

SUBJECTS AND METHODS

Between 1989-2000, 59 suitable hypodontia patients were identified of whom 45 had complete records. For these patients 73 resin-bonded bridges (RBBs) were provided. Following invitation, 24 patients attended for a review appointment. The survival of the RBBs, grade of operator providing treatment, duration of post-orthodontic retention, the influence of design, presence of pontic contact in static and dynamic excursions, and the effect of habits were assessed. Life table, Kaplan-Meier and Cox regression analysis were carried out for the 73 RBBs with complete records. A separate analysis of the RBBs provided for patients who attended for the invited review did not show a higher failure rate than those patients who did not attend. Therefore both sets of data were combined.

RESULTS

Of the 73 RBBs provided, 30 had debonded on at least one occasion (41.1%), six of these debonds were due to trauma (20%). The mean survival time of all the restorations was 59.3 months, with a median survival time of 59 months. Senior members of staff (Consultant, Senior Lecturer or Specialist Trainee) provided most restorations (n = 39) and achieved the highest mean survival of 72.6 months and median survival time of 100+ months. RBBs provided by junior staff and students had significantly lower survival times (p <0.05) compared with senior staff. Risk of failure was 3.9 times greater with junior staff and 2.5 times greater with students (p = 0.01 and p = 0.02, respectively). Analysis of all the other factors investigated showed no statistical difference in survival times or in hazard ratios. Analysis of fixed/fixed versus cantilevered bridges was limited by the number of fixed/fixed bridges (n = 11), and only two cantilevered bridges with multiple abutments were provided; both failed within one month.

CONCLUSION

RBBs provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors can for many patients be an acceptable and definitive restoration. Experienced staff achieved the best results, but why this should be was not explained by the individual factors analysed in this study.

An investigation of aspects of design of resin-bonded bridges in general dental practice and hospital services

PURPOSE OF STUDY

To assess the design of resin-bonded bridges (RBBs) by dentists, the quality of information provided to a dental laboratory, and aid identification of best practice.

DESIGN

A retrospective case series study of slips for RBB construction, sent by hospital and general dental practitioners to a dental laboratory based in a postgraduate dental institute in Scotland, UK.

MAIN FINDINGS

384 forms were reviewed. For single-tooth replacements, 40% of designs for upper anterior bridges and 46% for lower posterior bridges were fixed-fixed (F-F) when a cantilever design was a better option. Thirty-six (9.3%) of RBB designs involved double abutting. On the laboratory forms, fewer than five (1%) cases included instructions about the thickness of the metal framework and in 48% there was no reference to the extension of the metal framework.

PRINCIPAL CONCLUSIONS

For single-tooth replacements, a relatively high percentage of dentists prescribed a fixed-fixed design for RBBs, despite the evidence advocating the use of a cantilever design. A significant number of dentists used double abutments. The information provided to the laboratory for the construction of resin-bonded bridges was often insufficient.