A multi-practice clinical study on posterior resin-bonded bridges: a 2.5-year interim report

Longevity of resin-bonded fixed partial dentures made of metal alloys: A review of the literature

Purpose In this review, we evaluate the survival rate of resin-bonded fixed partial dentures (RBFPDs) made of metal alloys.Methods An electronic search of English peer-reviewed dental literature on PubMed was conducted to identify all publications reporting on RBFPDs made of metal alloys until March 2019. The searched keywords were: bridge OR fixed partial denture OR fixed prosthesis OR fixed prostheses AND resin bonded AND metal OR alloy AND survival OR longevity (RBFPD was not included). Furthermore, the "Related Articles" feature of PubMed was used to identify further references of interest during the primary search. A definitive list of articles was screened to extract qualitative data after the application of the inclusion and exclusion criteria, and the results were analyzed.Results Overall, 977 publications were found through an electronic and manual search, out of which 130 articles were selected after screening based on title and abstract. A total of 52 publications passed the second review phase after assessment for eligibility, from which 24 studies were excluded after full-text screening. Finally, a total of 28 studies were selected.Conclusions The survival rate of RBFPDs differed greatly depending on the type of metal alloy, adhesion system, and observation period assessed, e.g. the 10-year survival rate ranged from 18% to 88%. The wide range of survival rates of the RBFPDs reported indicates that though RBFPD is a reliable prosthesis, it is prone to failure if some processes are not completed.

Clinical Performance of Posterior Inlay-Retained and Wing-Retained Monolithic Zirconia Resin-Bonded Fixed Partial Dentures: Stage One Results of a Randomized Controlled Trial

PURPOSE

To prospectively compare the clinical performance of posterior inlay-retained and wing-retained monolithic zirconia fixed partial dentures (FPDs).

MATERIALS AND METHODS

After simple randomization, 30 participants received either one inlay-retained (n = 15; mean age: 56.38 ± 12.70 years; 10 men [66.7%]) or one wing-retained (n = 15; mean age: 45.90 ±13.24 years; 7 men [46.7%]) FPD. The restorations, which predominantly replaced first molars, were fabricated from translucent, 3 mol% yttria-stabilized zirconia and attached with self-etching resin cement. Restorations and abutment teeth were clinically followed up for complications one week and 3, 6, and 12 months after cementation. Plaque and gingival scores, probing pocket depths, and attachment levels were recorded for the abutment and contralateral reference teeth both before treatment and during follow-up examinations. The restorations were also assessed in accordance with FDI World Dental Federation criteria. Statistical analyses were conducted with R (α = 0.05). An adaptive, 2-stage study design based on the incidence of failure-free survival in the groups after 12 months (stage 1) was implemented. Predefined decision rules were used to determine whether further recruitment (stage 2) would enable the detection of a statistically significant difference between the restoration designs with sufficient power.

RESULTS

During 12 months, only one wing retainer debonded which required removal of the FPD. Failure-free survival was thus 93.3% for wing-retained and 100% for inlay-retained FPDs (log-rank test, p = 0.317). Moderate aftercare resulted in intervention-free rates of 78.8% and 86.7% for inlay-retained and wing-retained restorations, respectively (log-rank test, p = 0.605). Based on FDI World Dental Federation criteria, all restorations were acceptable at the 12-month follow-up (Fisher-Boschloo test, p = 0.161). Plaque, gingival, and periodontal scores remained practically unchanged from before treatment to the 12-month follow-up. Recruitment was stopped after stage 1 because, based on the small difference in the incidence of failure-free survival in the groups, it was accepted that it would not be possible to recruit the necessary number of participants to show a statistically significant difference between the retainer designs.

CONCLUSIONS

Both inlay-retained and wing-retained monolithic zirconia resin-bonded FPDs performed well for the 12-month, short-term follow-up period.

WITHDRAWN: Interventions for replacing missing teeth: partially absent dentition

BACKGROUND

Management of individuals presenting with partial loss of teeth is a common task for dentists. Outcomes important to the management of missing teeth in the partially absent dentition should be systematically summarized. This review recognizes both the challenges associated with such a summarization and the critical nature of the information for patients.

OBJECTIVES

To assess the effects of different prostheses for the treatment of partially absent dentition in terms of the following outcomes: long-term success, function, morbidity and patient satisfaction.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 21 March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to March 2011) and EMBASE via OVID (1980 to March 2011). There were no restrictions regarding language or date of publication. We contacted several authors to identify non-published trials.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing different methods (including the design and materials used) of treating partial edentulism, with clinically relevant outcomes, were included in this review. Trials reporting only surrogate outcomes, such as plaque accumulation or gingival volume, were excluded from this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently carried out the screening of eligible studies, assessment of dimensions of quality of trials, and data extraction. Results were expressed as mean differences for continuous data, risk ratios for dichotomous outcomes, and hazard ratios with 95% confidence intervals for time-to-event data.

MAIN RESULTS

Twenty-one trials met the inclusion criteria for this review. Twenty-four per cent of these were assessed as being at high risk of bias and the remainder were at unclear risk of bias. The clinical heterogeneity among the included studies precluded any attempt at meta-analysis. There was insufficient evidence to determine whether one type of removable dental prosthesis (RDP) was better or worse than another. With fixed dental prostheses (FDPs), there was no evidence that high gold alloys are better or worse than other alloys, nor that gold alloys or frameworks are better or worse than titanium. There is insufficient evidence to determine whether zirconia is better or worse that other FDP materials, that ceramic abutments are better or worse than titanium, or that one cement was better or worse than another in retaining FDPs. There is insufficient evidence to determine the relative effectiveness of FDPs and RDPs in patients with shortened dental arch or to determine the relative advantages of implant supported FDPs versus tooth/implant supported FDPs.

AUTHORS' CONCLUSIONS

Based on trials meeting the inclusion criteria for this review, there is insufficient evidence to recommend a particular method of tooth replacement for partially edentulous patients.

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.

Interventions for replacing missing teeth: partially absent dentition

BACKGROUND

Management of individuals presenting with partial loss of teeth is a common task for dentists. Outcomes important to the management of missing teeth in the partially absent dentition should be systematically summarized. This review recognizes both the challenges associated with such a summarization and the critical nature of the information for patients.

OBJECTIVES

To assess the effects of different prostheses for the treatment of partially absent dentition in terms of the following outcomes: long-term success, function, morbidity and patient satisfaction.

SEARCH METHODS

We searched the Cochrane Oral Health Group's Trials Register (to 21 March 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 1), MEDLINE via OVID (1950 to March 2011) and EMBASE via OVID (1980 to March 2011). There were no restrictions regarding language or date of publication. We contacted several authors to identify non-published trials.

SELECTION CRITERIA

Randomized controlled trials (RCTs) comparing different methods (including the design and materials used) of treating partial edentulism, with clinically relevant outcomes, were included in this review. Trials reporting only surrogate outcomes, such as plaque accumulation or gingival volume, were excluded from this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently carried out the screening of eligible studies, assessment of dimensions of quality of trials, and data extraction. Results were expressed as mean differences for continuous data, risk ratios for dichotomous outcomes, and hazard ratios with 95% confidence intervals for time-to-event data.

MAIN RESULTS

Twenty-one trials met the inclusion criteria for this review. Twenty-four per cent of these were assessed as being at high risk of bias and the remainder were at unclear risk of bias. The clinical heterogeneity among the included studies precluded any attempt at meta-analysis. There was insufficient evidence to determine whether one type of removable dental prosthesis (RDP) was better or worse than another. With fixed dental prostheses (FDPs), there was no evidence that high gold alloys are better or worse than other alloys, nor that gold alloys or frameworks are better or worse than titanium. There is insufficient evidence to determine whether zirconia is better or worse that other FDP materials, that ceramic abutments are better or worse than titanium, or that one cement was better or worse than another in retaining FDPs. There is insufficient evidence to determine the relative effectiveness of FDPs and RDPs in patients with shortened dental arch or to determine the relative advantages of implant supported FDPs versus tooth/implant supported FDPs.

AUTHORS' CONCLUSIONS

Based on trials meeting the inclusion criteria for this review, there is insufficient evidence to recommend a particular method of tooth replacement for partially edentulous patients.

Sequential analysis applied to clinical trials in dentistry: a systematic review

Clinical trials employ sequential analysis for the ethical and economic benefits it brings. In dentistry, as in other fields, resources are scarce and efforts are made to ensure that patients are treated ethically. The objective of this systematic review was to characterise the use of sequential analysis for clinical trials in dentistry. We searched various databases from 1900 through to January 2008. Articles were selected for review if they were clinical trials in the field of dentistry that had applied some form of sequential analysis. Selection was carried out independently by two of the authors. We included 18 trials from various specialties, which involved many different interventions. We conclude that sequential analysis seems to be underused in this field but that there are sufficient methodological resources in place for future applications.Evidence-Based Dentistry (2008) 9, 55-62. doi:10.1038/sj.ebd.6400587.

Survival rates of resin-bonded, glass fiber–reinforced composite fixed partial dentures with a mean follow-up of 42 months: A pilot study

STATEMENT OF PROBLEM

Although short-term clinical data exist for resin-bonded, glass fiber-reinforced composite fixed partial dentures (FPDs), long-term data are needed.

PURPOSE

The survival rates of 29 resin-bonded, glass fiber-reinforced composite fixed partial dentures were evaluated in this clinical study for periods of up to 42 months.

MATERIAL AND METHODS

FPDs were fabricated to replace 1 to 3 missing maxillary or mandibular teeth of 29 patients not able to be treated with conventional FPDs. Originally, there were 37 patients (the drop-out rate was 22%). The FPDs were retained with wings, inlays, complete coverage crowns, or combinations of these that were bonded to tooth structure. The FPD frameworks were made of continuous unidirectional E-glass fibers with a multiphase polymer matrix and light-polymerized particulate composite veneer. The patients were recalled for examinations, where a general dental examination was performed, 1 to 3 times per year for up to 63 months (minimum 24 months, mean 42 months). Partial or complete total debonding of the FPD or the framework fracture was considered a treatment failure. The data were analyzed with the Kaplan-Meier survival test (alpha=.05).

RESULTS

Two resin frameworks fractured, and 3 frameworks were debonded. Kaplan-Meier survival probability at 63 months was 75%. Three of the failed FPDs were rebonded or repaired in situ, producing a functional survival rate of 93% after rebonding or repairing (mean survival time was 55 months).

CONCLUSION

The results of this clinical study of 29 prostheses suggest that glass fiber-reinforced FPDs may be a possible alternative to cast metal resin-bonded FPDs. These restorations were successfully used as multiple-unit prostheses that employed a variety of abutment tooth preparation designs.

Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties

The purpose of this study was to determine changes in flexural properties of resin cement under simulated resin-bonded fixed partial denture (RBFPD) clinical conditions using aqueous ageing and cyclic loading. Panavia F flexural modulus and strength were measured by static loading to failure after 48-h and 60-day aqueous ageing at 37 degrees C with and without simulated cyclic occlusal loading. Panavia F sorption and solubility were also measured. Scanning electron microscopy (SEM) was used to characterize the morphology of the fractured surfaces. A two-factor anova (P </= 0.05) indicated that cyclic loading produced a significant increase in the flexural modulus with no significant effect on the flexural strength. Conversely, aqueous ageing time produced a significant decrease in flexural strength with no effect on the flexural modulus. The SEM fracture analysis indicated that resin matrix fracture occurred in static-aqueous specimens; while in the aqueous-cycled specimens, resin matrix fracture occurred in addition to an increasing proportion of filler/resin interface fracture. Collectively, these outcomes suggest that initial degradation under simulated resin cement clinical function may be related to breakdown of the filler/resin interface bond, which could contribute to in vivo RBFPD resin cement cohesive failure.

Clinical complications in fixed prosthodontics

The purpose of this article is to identify the incidence of complications and the most common complications associated with single crowns, fixed partial dentures, all-ceramic crowns, resin-bonded prostheses, and posts and cores. A Medline and an extensive hand search were performed on English-language publications covering the last 50 years. The searches focused on publications that contained clinical data regarding success/failure/complications. Within each type of prosthesis, raw data were combined from multiple studies and mean values calculated to determine what trends were noted in the studies. The lowest incidence of clinical complications was associated with all-ceramic crowns (8%). Posts and cores (10%) and conventional single crowns (11%) had comparable clinical complications incidences. Resin-bonded prostheses (26%) and conventional fixed partial dentures (27%) were found to have comparable clinical complications incidences. The 3 most common complications encountered with all-ceramic crowns were crown fracture (7%), loss of retention (2%), and need for endodontic treatment (1%). The 3 most common complications associated with posts and cores were post loosening (5%), root fracture (3%), and caries (2%). With single crowns, the 3 most common complications were need for endodontic treatment (3%), porcelain veneer fracture (3%), and loss of retention (2%). When fixed partial denture studies were reviewed, the 3 most commonly reported complications were caries (18% of abutments), need for endodontic treatment (11% of abutments), and loss of retention (7% of prostheses). The 3 most common complications associated with resin-bonded prostheses were prosthesis debonding (21%), tooth discoloration (18%), and caries (7%).

Experimentally induced abutment strains in three types of single-molar implant restorations

STATEMENT OF PROBLEM

The choice of single-molar implant design is difficult because of a lack of controlled, quantitative biomechanical analyses.

PURPOSE

This study determined the effect of 3 single-molar implant designs on implant strains under a variety of homologous loading conditions.

MATERIAL AND METHODS

On each implant abutment, 4 strain gauges were placed axially at 90 degrees to each other on the buccal, lingual, mesial, and distal surfaces. Effects of implant design, load location, direction, and magnitude were tested on axial and bending (buccolingual and mesiodistal) strains of 3 single-molar implant designs: (1) single, 3.75-mm (regular) diameter implant, (2) single, 5-mm (wide) diameter implant, and (3) two 3.75-mm diameter (double) implants connected through a single-molar crown. Results were analyzed with ANOVA.

RESULTS

Variations in loading conditions induced 3-dimensionally complex abutment strains on the tested implant designs. Peak absolute strains in mesiodistal direction were 6493 microepsilon for design 1 and 3958 microepsilon on design 2, and 3160 microepsilon in buccolingual direction on design 3. For all loading conditions, the single 3.75-mm diameter implant consistently experienced the largest strains compared with wide-diameter and double implant designs. Changes in centric contact location affected implant abutment strains differently among the 3 designs. Angulated force direction resulted in larger bending strains.

CONCLUSION

For single-molar implant designs, an increase in implant number and diameter may effectively reduce experimental implant abutment strains.

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.

Risk factors and multiple failures in posterior resin-bonded bridges in a 5-year multi-practice clinical trial

OBJECTIVES

A randomized controlled clinical trial was undertaken, to study the influence of some patient- and operator-dependent variables on the survival of posterior resin-bonded bridges (PRBBs) and to assess the survival of replacement' PRBBs. This report contains some of the results of the 5-year analysis.

METHODS

Survival was defined at three levels: (1) complete survival (without any debonding), (2) functional survival (i.e. survival after one loss of retention) and (3) replacement survival (survival of 'replacement' PRBBs, inserted after rebonded bridges suffered a second dislodgement). Potential risk factors were analysed with Cox's proportional hazards model and differences were tested for significance with the Breslow test. Observed effects are expressed as conditional-relative-risk (CRR). Survival of 'replacement' PRBBs was assessed with the Kaplan-Meier method.

RESULTS

Factors showing significant influences on complete survival were: 'location' (highest risk for mandibular PRBBs: CRR = 2.2), 'aetiology' (higher risk in treatment of aplasia: CRR = 2.9), and 'time of existence' (open spaces existing less than 2 years before insertion of PRBB: CRR: 2.0). The factor 'large open spaces in the mandible' was a risk for both complete and functional survival (CCR values 3.1 and 3.5, respectively). The survival of mandibular and maxillary 'replacement' PRBBs after 5 years was 19 +/- 7% and 31 +/- 18%, respectively.

CONCLUSIONS

Risk factors for PRBBs were: 'location', 'aetiology', 'time of existence', 'isolation method' and 'large open spaces in the mandible'. Mandibular 'replacement' PRBBs showed such an unacceptably low survival rate that fabrication is not recommended.

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.

Phosphate and thiophosphate primers for bonding prosthodontic luting materials to titanium

STATEMENT OF PROBLEM

When resin-bonded prostheses are constructed with titanium, they must be strongly bonded with luting materials for the prostheses to withstand the oral environment over the long term. However, limited information is available about the bond durability between luting materials and titanium.

PURPOSE

This study determined whether a phosphate and two thiophosphate primers increase bond strength and durability between a commercially available pure titanium and four luting agents.

MATERIAL AND METHODS

Three primers and four luting agents were divided into three groups according to the type of acidic monomers: carboxylic acid derivatives (4-META, 4-AET, and MAC10), a phosphoric acid derivative (MDP), and a thiophosphoric acid derivative (MEPS). Disk specimens were bonded with 16 combinations of 3 primers and 4 luting agents, including 4 controls. Shear bond strengths were determined after 1-day immersion in water and after thermocycling for 100,000 cycles.

RESULTS

Bond strengths were influenced by thermocycling, primer, luting agent, and their combinations. After thermocycling, the groups that demonstrated the highest bond strengths were six combinations of two primers (Cesead Opaque Primer and Metal Primer II) and three luting agents (Imperva Dual, Panavia 21, and Super-Bond C&B).

A five-year multi-practice clinical study on posterior resin-bonded bridges

Previous clinical observations have revealed that resin-bonded bridges for posterior tooth replacements are less retentive than anterior resin-bonded bridges. Improved bonding procedures and preparation designs, however, may have a positive effect on the functional durability of these restorations. The present study reports the final analysis of a randomized controlled clinical trial in which different designs of posterior resin-bonded bridges were evaluated for a period of at least 5 years. The operational hypothesis was that the bonding system and the preparation design used in posterior resin-bonded bridges have an influence on the survival and clinical functioning of these restorations. Survival in this study was defined at two levels: (1) 'complete' survival (survival without any debonding), and (2) 'functional' survival (survival including loss of retention on one occasion and successful rebonding of the original RBB without further debonding). With regard to 'complete' survival, no significant differences were found between the bonding systems used for adherence of the restorations to abutment teeth (etching/Clearfil F2, sandblasting/Panavia EX, and silica-coating/Microfill Pontic C). The variable 'preparation form' (conventional preparation form vs. modified preparation form) for complete survival was statistically in favor of the modified preparation form (62% vs. 46%), but did not influence the functional survival. With regard to 'functional' survival, the combination of silica coating and Microfill Pontic C was more retentive than the other bonding systems (90% survival vs. 72% and 75%, p < 0.01). Factor location was found to be highly significant for both survival levels [Cox's PH model, p = 0.0002 (Cox, 1972)]: The five-year 'complete' survival rates were 65% for maxillary restorations and 40% for mandibular restorations, while the five-year 'functional' survival rates were 89% and 68%, respectively. It is concluded that preparation of grooves in abutment teeth for posterior resin-bonded bridges is beneficial to their chance of survival. Resin-bonded bridges placed in the maxilla have a better prognosis than those made in the mandible. The bonding systems used in this study appear to have no influence on the chance of failure. In rebonded posterior resin-bonded bridges, the bonding system silica-coating/Microfill Pontic C was more retentive than the other systems tested.

Long-term survival data from a clinical trial on resin-bonded bridges

OBJECTIVES

A clinical trial, involving 203 resin-bonded bridges (RBBs) was undertaken to investigate the influence of retainer-type and luting material on the survival of these restorations.

METHODS

For this evaluation, 157 patients were available (14% of the original sample was lost to follow-up or excluded from the study following the stopping criteria). Fifty per cent of the patients were questioned concerning the fate of the RBBs and 59% of questioned patients were examined clinically. The patients that were seen for examination were representatives of the experimental groups. The findings from the clinical examination were compared with the data obtained from the questionnaire. Missing data were censored at the date of the last available information. Kaplan-Meier estimates were calculated to assess the survivals at the endpoints and compared using Cox's proportional hazards procedure.

RESULTS

A significant difference was found between perforated (P-type) and etched (E-type) RBBs (P = 0.05) for original bonded restorations but not when rebonded RBBs were taken into account. The results of the survival analysis were: anterior P-type, 49 +/- 7% after 10.5 years: anterior E-type, 57 +/- 7% after 10.5 years; posterior P-type, 18 +/- 11% after 6.8 years; posterior E-type, 37 +/- 13% after 10.2 years. Survivals of RBBs that were rebonded once during the evaluation period were 62 +/- 9% (11.0 years) for anterior RBBs and 51 +/- 11% (10.2 years) for posterior RBBs.

CONCLUSIONS

The factor location (anterior versus posterior) was as in previous analyses, highly significant. Differences in survival between cementation materials were not significant.

Primer for bonding resin to metal

OBJECTIVES

The purpose was to examine the effect on the bond strength and durability of a resin bond to metal of modification of a primer consisting of thiophosphoric methacrylate with phosphoric methacrylates and/or benzoyl peroxide.

METHODS

Acrylic rods were bonded with a luting resin consisting of poly(methyl methacrylate) powder and a mixture of methyl methacrylate and tributylborane initiator to silver-palladium alloy (Ag-Pd), gold-silver alloy (Au-Ag), cobalt-chromium alloy (Co-Cr), and titanium (Ti) surfaces treated with various primers. The bonded samples were thermocycled for 2,000 cycles and the mean bond strengths were compared using one-way ANOVA and Duncan's new multiple range test at p < 0.05.

RESULTS

Using primers of thiophosphoric methacrylate or phosphoric methacrylates alone, the bond strengths of Ag-Pd decreased significantly (p < 0.05) after thermocycling. The durability was significantly improved (p < 0.05) when thiophosphoric methocrylate was used in combination with the phosphate monomers. The additional use of benzoyl peroxide and heat treatment resulted in a significant increase (p < 0.05) in the durability of two groups; the mean bond strengths over 20 MPa and the lowest values remained unchanged even after 2,000 thermocycles.

SIGNIFICANCE

The highest level of bond strength and durability to dental noble metals was achieved using a mixture of thiophosphoric and phosphoric methacrylates and benzoyl peroxide. These bond strength results are comparable to values obtained for base metals.