Fracture characteristics of anterior resin-bonded zirconia-fixed partial dentures

Fracture strength of anterior cantilever resin-bonded fixed partial dentures fabricated from high translucency zirconia with different intaglio surface treatments

PURPOSE

To compare the fracture resistance and failure modes of anterior cantilever resin-bonded fixed partial dentures (RBFPDs) fabricated from high translucency zirconia with different intaglio surface treatments.

MATERIALS AND METHODS

Sound-extracted canines (N = 50) were randomly divided into five groups (n = 10) to be restored with high translucency zirconia RBFBDs of different intaglio surface treatments. The RBFPD was designed using exocad software and fabricated using a CAM milling machine. The RBFPDs were treated differently: abrasion with 50 µm alumina particles (Group 1); abrasion with 30 µm silica-coated alumina particles (Group 2); abrasion with silica-coated alumina particles (30 µm) and silane application (Group 3); abrasion with silica-coated alumina particles (30 µm) and 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) primer application (Group 4); abrasion with silica-coated alumina particles (30 µm) and silane, and 10-MDP primer application. All RBFPDs were cemented using dual-cured resin cement. The RBFPDs underwent 6000 thermal cycles with distilled water at 5/55°C for 2 min per cycle and then mechanical cyclic loading with 1200,000 cycles of 50 N at a 1.7 Hz frequency at an angle of 135° to the abutment's long axis. Then, RBFPDs were loaded to fracture using a universal testing machine at 1 mm/min. Maximum fracture forces and failure modes were recorded. Fractured specimens and uncemented specimens were examined using a scanning electron microscope. Data was analyzed using ANOVA and Games-Howell post hoc tests at p < 0.05.

RESULTS

Mean fracture load results showed a statistically significant difference between the research groups (p < 0.0001) and it ranged from 69.78 to 584 N. Group 4 exhibited the highest fracture load mean (p < 0.0001) which was significantly different from all other groups. Group 2 recorded a significantly higher fracture load mean than Group 3 (p = 0.029). Three modes of failure were observed: prosthesis debonding, prosthesis fracture, and abutment fracture.

CONCLUSIONS

Abrasion of zirconia surface with 30 µm silica-coated alumina particles and application of 10-MDP primer yielded the highest mean fracture loads of monolithic high translucency zirconia RBFPD. The mode of fracture of the RBFPDs was influenced by the type of surface treatments.

Terminology focused on design and retention methods used for anterior resin-bonded fixed partial dentures in English literature: A scoping review

Purpose

Novel terms describing several designs of resin-bonded fixed partial dentures (RBFPDs) continue to appear. Indeed, a variety of terms are used in the English scientific literature The use of a standard terminology is important for a fair and efficient understanding. This study aimed to investigate if the terminology used to describe designs and retention methods for anterior RBFPDs is standard.

Methods

An electronic search in the English literature was conducted in PubMed/Medline to identify all publications reporting RBFPDs in the anterior region until August 2022. This search was completed by hand searching. Terms indicating different designs of RBFPDs were listed and then classified. Percentages of their use were calculated to determine the commonly used terms. Analysis of the use of these terms was performed based on the standards determined by the latest edition of the Glossary of Prosthodontic Terms (GPT). The impacts of the MeSH Thesaurus and GPT on the nomenclature used for RBFPDs was assessed.

Results

A total of 125 articles were eligible for this review. In the retained articles, 86 terms were found. Among them, thirty-nine terms were classified into three groups. Only six terms were defined in the latest edition of GPT (GPT-9). Several classified terms that are commonly used were not identified in the GPT-9. Conversely to the GPT-9 which impact was insignificant, the MeSH Thesaurus had an important impact on the nomenclature used for RBFPDs.

Conclusion

The terminology used to describe designs and retention methods for anterior RBFPDs was non-standard. The GPT-9, constituting an important reference, defined a limited number of terms related to RBFPDs and had no significant impact on the standardization of the terminology used for RBFPDs. Efforts should therefore be continued to standardize the terminology. A specialized mini-glossary grouping and defining all the terms found in this study will helpful in clarifying the terminology used for the anterior RBFPDs.

Bonding Performance of Surface-Treated Zirconia Cantilevered Resin-Bonded Fixed Dental Prostheses: In Vitro Evaluation and Finite Element Analysis

Debonding of zirconia cantilevered resin-bonded fixed dental prostheses (RBFDPs) remains the main treatment complication, therefore, the present in vitro study aimed to evaluate the effect of different surface pretreatments on the bonding of zirconia RBFDPs. Eighty milled zirconia maxillary central incisors, with complementary zirconia cantilevered RBFDPs, were randomly subjected to four different surface pretreatments (n = 20): as-machined (AM); airborne-particle abraded (APA); coated with nanostructured alumina coating (NAC); incisor air-abraded and RBFDP coated (NAC_APA). After bonding, half of each group (n = 10) was stored in deionized water (150 days/37 °C), thermocycled (37,500 cycles, 5-55 °C), and cyclically loaded (50 N/1.2 × 10⁶). Load-bearing capacity (LBC) was determined using a quasi-static test. Additionally, finite element analysis (FEA) and fractography were performed. t-test and one-way ANOVA were used for statistical-analysis. Before aging, the NAC group provided superior LBC to other groups (p < 0.05). After aging, the AM specimens debonded spontaneously, while other groups exhibited comparable LBC (p ˃ 0.05). The FEA results correlated with the in vitro experiment and fractography, showing highly stressed areas in the bonding interface, cement layer, and in RBFDP's retainer wing and connector. The NAC RBFDPs exhibited comparable long-term bonding performance to APA and should be regarded as a zirconia pretreatment alternative to APA.

The Success Rate of the Adhesive Partial Fixed Prosthesis after Five Years: A Systematic Review

Objective: Evaluation of the success and/or survival rates of resin-bonded fixed partial dentures (RBFPDs) reported in the scientific literature with a minimum average observation time of five years. Materials and Methods: Search conducted in Pubmed, Web of Science, and Cochrane databases in free-text format and MESH terms, until May 2021. The random-effects model was used for the estimated survival rate, percentage per year of estimated failure, and existing complications for the meta-analysis. Study heterogeneity was assessed by the inconsistency test (I2) and study quality by the Downs and Black scale. Results: Eleven articles were included, with 687 participants and 783 RBFPDs, with a mean observation time of 8.2 years, with success rates mentioned in three articles and survival rates reported in nine articles. A total of 142 failures were reported for 783 prostheses, the most frequent being debonding. The estimated failure rate was between 0.53% and 5.10% per year. The studies were of sufficient quality. In the meta-analysis, the survival rates showed a significant result (p < 0.001), with moderate heterogeneity (I2 = 58.76%). Conclusions: Within the limitations of this research, mainly related to the heterogeneity of the studies and their quality, it seems possible to conclude that RBFPDs are a viable clinical option for the rehabilitation of patients with single edentulous spaces, mainly when using a single retainer and a zirconia-ceramic prosthesis.

Durability of cantilever inlay-retained fixed dental prosthesis fabricated from multilayered zirconia ceramics with different designs

PURPOSE

The purpose of this in-vitro study was to investigate the effect of framework design on fracture resistance and failure modes of cantilever inlay-retained fixed partial dentures (IRFDPs) fabricated from two multilayered monolithic zirconia materials.

MATERIALS AND METHODS

Seventy-two natural premolar teeth were prepared as abutments for cantilever IRFDPs using three designs: mesial-occlusal (MO) inlay with short buccal and palatal wings (D1), MO inlay with long palatal wing (D2), MO inlay with long palatal wing and occlusal extension (D3). Full-contoured IRFDPs were fabricated from two monolithic zirconia materials; IPS e.max ZirCAD Prime and Zolid Gen-X. Adhesive surfaces were air-abraded and bonded with MDP-containing resin cement. Specimens were subjected to thermocycling (5-55 °C, 5000 cycles); then, mechanical loading (1.2 × 10⁶ cycles, 49 N). Surviving specimens were loaded until failure in the universal testing machine. All specimens were examined under stereomicroscope, and two samples from each group were evaluated using Scanning Electron Microscope.

RESULTS

Mean failure loads were not significantly different between different framework designs or between two materials. However, IPS e.max ZirCAD Prime showed significantly higher failure rate than Zolid Gen-X during dynamic fatigue (p = 0.009). Samples with D1 design showed higher debonding rate, D2 failed mainly by fracture of the palatal wing and debonding, and D3 failed mainly by fracture of the abutment tooth. Debonded restorations showed mainly mixed failures.

CONCLUSION

Cantilever IRFDPs with framework designs that maximize adhesion to enamel exhibited promising results. IPS e.max ZirCAD Prime was more susceptible to fractures with the long palatal wing design.

Strain analysis of anterior resin-bonded fixed dental prostheses with different thicknesses of high translucent zirconia

Background/purpose

High translucent zirconia has been used as a new monolithic zirconia prosthesis, which has the potential to make anterior resin-bonded fixed dental prostheses (RBFDPs) without veneering porcelain. However, it is unclear whether the RBFDPs retainer can be thinned as much as conventional zirconia RBFDPs. The aim of this study was to assess the usability of high translucent zirconia RBFDPs with a thin retainer thickness by evaluating differences in retainer thickness on the surface strain.

Materials and methods

A model with a missing upper lateral incisor was used. The abutment teeth were upper central incisor and canine. Three types of RBFDPs were fabricated as follows: metal RBFDPs with a retainer thickness of 0.8 mm (0.8M), and high translucent zirconia RBFDPs with a retainer thicknesses of 0.8 and 0.5 mm (0.8Z, 0.5Z) (n = 10). The fitness of the margins was evaluated by the silicone replica technique. The surface strain of each retainer under static loading was measured and statistically analyzed using a t-test with Bonferroni correction.

Results

The marginal fitness of all RBFDPs was under 76.1 μm, which was clinically acceptable. Each strain of the 0.8Z and 0.5Z groups was significantly lower than that of the 0.8M (p < 0.05). There was no difference in strain of the zirconia RBFDPs even if the retainer thickness was changed.

Conclusion

Our results suggest that the high translucent zirconia RBFDPs can be manufactured with a retainer thickness of 0.5 mm, which reduces the amount of tooth preparation compared to the metal RBFDPs.

Glass-ceramic resin-bonded fixed partial dentures for replacing a single premolar tooth: A prospective investigation with a 4-year follow-up

STATEMENT OF PROBLEM

Resin-bonded fixed partial dentures (RBFPDs) are a reliable treatment option for the replacement of a single missing tooth. Glass-ceramic may be a promising material for the fabrication of RBFPDs, but clinical verification has been lacking.

PURPOSE

The purpose of this prospective clinical study was to evaluate the outcomes of glass-ceramic RBFPDs on participants with a single missing premolar.

MATERIAL AND METHODS

Twenty participants (6 men, 14 women; age range: 20 to 54 years) were treated with 2-retainer RBFPDs. These RBFPDs were made of lithium disilicate glass-ceramic (IPS e.max Press; Ivoclar Vivadent AG) and designed with improved C-shaped retention. These prostheses were evaluated at 6 months, 12 months, and annually thereafter and were classified as survival or failure. Analysis was performed with the Kaplan-Meier analysis (95% confidence interval). Modified United States Public Health Service (USPHS) criteria were used to rate the clinical performance. Parameters assessed were fracture, marginal integrity, marginal discoloration, color of restoration, secondary caries, and abutment mobility.

RESULTS

Twenty RBFPDs were provided, 9 in the maxilla and 11 in the mandible. The mean observation time was 49.2 months (minimum 9 months, maximum 53 months). Nineteen RBFPDs were evaluated as having survived during the observation period with some acceptable marginal discoloration, 1 RBFPD had to be replaced because of fracture and secondary caries and was evaluated as a failure. The Kaplan-Meier analysis revealed a survival rate of 95% after a 4-year observation.

CONCLUSIONS

The glass-ceramic RBFPDs in this study displayed a good survival rate and clinical performance, indicating that glass-ceramic RBFPDs might be a promising approach for the short-term replacement of a single premolar. However, further investigations are needed to determine the long-term outcome.

Evolution of Indirect Restorations for Fixed Prosthodontics: Planning, Preparation and Cementation

The provision of indirect restorations utilising contemporary materials for single or multiple abutment units in primary health care is an essential requirement for all general dental practitioners to ensure predictable patient outcomes. This paper highlights the important considerations for comprehensive planning and adept treatment execution and delivery that can enhance the patient's dental experience and outcome. A selection of clinical cases highlighting established and novel restorative materials utilising conventional and adhesive clinical techniques is presented and discussed.

A low cost minimally invasive adhesive alternative for maxillary central incisor replacement

OBJECTIVE

The beneficial mechanical properties of zirconia, together with the adhesive techniques, provide a wide range of clinical applications, including the construction of thin structures and minimally invasive adhesive restorations.

CLINICAL CONSIDERATIONS

A periodontal disease-related missing maxillary central incisor, in a pregnant patient with chronic periodontal disease in the first trimester of pregnancy, and with type II diabetes treated with resin-bonded fixed partial denture using the missing tooth cemented to a zirconia framework and then bonded to the abutment teeth.

CONCLUSIONS

According to the systemic conditions presented in this case report, using a low-cost technology and the missing tooth it was possible to obtain an easier and satisfactory esthetic and functional result.

CLINICAL SIGNIFICANCE

The mechanical properties of zirconia made it possible to treat a pregnant patient with chronic periodontal disease in the first trimester of pregnancy, and with type II diabetes with a thin zirconia framework and minimally invasive adhesive restorations.

Biomechanical behavior of adhesive cement layer and periodontal tissues on the restored teeth with zirconia RBFDPs using three-kinds of framework design: 3D FEA study

PURPOSE

To investigate stress and strain concentrations on resin-bonded fixed dental prostheses (RBFDPs) frameworks of different design using finite element analysis.

METHODS

A human dry skull was scanned and models were produced using three-dimensional printer. After abutment preparation, three frameworks, including a three-unit RBFDP, and two-unit cantilevered RBFDPs using #21 and #23 for the abutment tooth, were fabricated. Scanned data were subtracted to define boundary of each structure. Occlusal force (200N) was loaded at 45° to long axis of the pontic. The distributions of shear stress and principal strain in the RBFDP models were measured to evaluate the risk for framework-debonding from the abutment teeth and the impact on periodontal tissue.

RESULTS

The percentage voxels with shear stress >11MPa in adhesive cement layer of three-unit RBFDP using #21 and #23 were 4.16% and 2.25%, respectively; in two-unit cantilevered RBFDPs, it was 19.25% using #21, and 23.4% using #23. The maximum principal strain on periodontal ligaments in two-unit cantilevered RBFDPs using #21 was the largest, and smallest in the three-unit RBFDP. The maximum principal strain in framework was largest in the two-unit cantilevered RBFDP using #23, and smallest in the three-unit RBFDP.

CONCLUSIONS

The risk for framework-debonding in three-unit RBFDPs was substantially lower than that in two-unit RBFDPs. In difficult cases with indication for three-unit RBFDPs, two-unit cantilever design using the canine would be more advantageous for preservation of periodontal tissue, while for risk of framework-debonding, the design using the central incisor would be more advantageous.

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.

Three-dimensional finite element analysis of anterior two-unit cantilever resin-bonded fixed dental prostheses

The aim of this study was to evaluate the influence of different framework materials on biomechanical behaviour of anterior two-unit cantilever resin-bonded fixed dental prostheses (RBFDPs). A three-dimensional finite element model of a two-unit cantilever RBFDP replacing a maxillary lateral incisor was created. Five framework materials were evaluated: direct fibre-reinforced composite (FRC-Z250), indirect fibre-reinforced composite (FRC-ES), gold alloy (M), glass ceramic (GC), and zirconia (ZI). Finite element analysis was performed and stress distribution was evaluated. A similar stress pattern, with stress concentrations in the connector area, was observed in RBFDPs for all materials. Maximal principal stress showed a decreasing order: ZI > M > GC > FRC-ES > FRC-Z250. The maximum displacement of RBFDPs was higher for FRC-Z250 and FRC-ES than for M, GC, and ZI. FE analysis depicted differences in location of the maximum stress at the luting cement interface between materials. For FRC-Z250 and FRC-ES, the maximum stress was located in the upper part of the proximal area of the retainer, whereas, for M, GC, and ZI, the maximum stress was located at the cervical outline of the retainer. The present study revealed differences in biomechanical behaviour between all RBFDPs. The general observation was that a RBFDP made of FRC provided a more favourable stress distribution.

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.

Effect of framework design on the surface strain of zirconia fixed partial dentures

The purpose of this study was to evaluate the design of resin-bonded fixed partial dentures (RBFPDs) with zirconia frameworks. The abutment teeth were the upper central incisor and the canine. Three types of frameworks were fabricated as follows: 0.5-mm- and 0.8-mm-thick zirconia frameworks with grooves and holes (0.5ZrG, 0.8ZrG) and 0.5-mm-thick zirconia frameworks without grooves and holes (0.5Zr). The control group was designed as a 0.8-mm-thick metal framework with grooves and holes (0.8MG). Static loading was applied and the surface strain of the retainers was measured with strain gages. The magnitude of the principal strain of the 0.5ZrG framework was significantly lower than that of the 0.8MG and the 0.5Zr frameworks. This result suggests that the zirconia and retention form had a significant effect on decreasing the framework deformation, indicating that the RBFPDs that use a 0.5-mm thick zirconia framework are effective for replacing a single anterior missing tooth.

Increased tooth mobility because of loss of alveolar bone support: a hazard for zirconia two-unit cantilever resin-bonded FDPs in vitro?

This study evaluates in vitro the impact of increased abutment tooth mobility on survival of zirconia-based two-unit cantilever resin-bonded fixed dental prosthesis (RB-FDP) by long-term dynamic loading in a chewing simulator. Human maxillary central incisors (n = 32) were endodontically treated and alveolar bone loss was simulated: 0% (group B), 25% (group C), and 50% (group D). RB-FDPs were adhesively luted. Zirconia full crown two-unit FDPs served as control (group A). Specimens were exposed to simulated clinical function by two subsequent sequences of thermal-cycling (2 × 3.000) parallel to mechanical loading (1.2 × 10(6) load cycles) (TCML; first sequence: load 1-25 N; second sequence: load 1-50 N). Tooth mobility increased significantly as the simulated bone level decreased (p < 0.001). Log-rank tests revealed no significant differences between experimental groups (p = 0.479). The results support the assumption that zirconia-based two-unit cantilever RB-FDPs may be an appropriate treatment option, even if abutment tooth mobility increase because of alveolar bone loss. However, debonding of zirconia-based two-unit RB-FDPs will be a likely event, whereas fatal failures of the abutment teeth may not occur.

Are implants more reliable than severely compromised endodontically treated teeth as abutments for zirconia-based FPDs? : In vitro results of long-term preclinical load simulation

OBJECTIVES

The aim was to study the impact of the defect size of endodontically treated incisors compared to dental implants as abutments on the survival of zirconia two-unit anterior cantilever-fixed partial dentures (2U-FPDs) during 10-year simulation.

MATERIALS AND METHODS

Human maxillary central incisors were endodontically treated and divided into three groups (n = 24): I, access cavities rebuilt with composite core; II, teeth decoronated and restored with composite; and III as II supported by fiber posts. In group IV, implants with individual zirconia abutments were used. Specimens were restored with zirconia 2U-FPDs and exposed to two sequences of thermal cycling and mechanical loading.

STATISTICS

Kaplan-Meier; log-rank tests.

RESULTS

During TCML in group I two tooth fractures and two debondings with chipping were found. Solely chippings occurred in groups II (2×), IV (2×), and III (1×). No significant different survival was found for the different abutments (p = 0.085) or FPDs (p = 0.526). Load capability differed significantly between groups I (176 N) and III (670 N), and III and IV (324 N) (p < 0.024).

CONCLUSION

Within the limitations of an in vitro study, it can be concluded that zirconia-framework 2U-FPDs on decoronated teeth with/without post showed comparable in vitro reliability as restorations on implants. The results indicated that restorations on teeth with only access cavity perform worse in survival and linear loading.

CLINICAL RELEVANCE

Even severe defects do not justify per se a replacement of this particular tooth by a dental implant from load capability point of view.

Influence of the supporting die structures on the fracture strength of all-ceramic materials

This study investigated the influence of the elastic modulus of supporting dies on the fracture strengths of all-ceramic materials used in dental crowns. Four different types of supporting die materials (dentin, epoxy resin, brass, and stainless steel) (24 per group) were prepared using a milling machine to simulate a mandibular molar all-ceramic core preparation. A total number of 96 zirconia cores were fabricated using a CAD/CAM system. The specimens were divided into two groups. In the first group, cores were cemented to substructures using a dual-cure resin cement. In the second group, cores were not cemented to the supporting dies. The specimens were loaded using a universal testing machine at a crosshead speed of 0.5 mm/min until fracture occurred. Data were statistically analyzed using two-way analysis of variance and Tukey HSD tests (α = 0.05). The geometric models of cores and supporting die materials were developed using finite element method to obtain the stress distribution of the forces. Cemented groups showed statistically higher fracture strength values than non-cemented groups. While ceramic cores on stainless steel dies showed the highest fracture strength values, ceramic cores on dentin dies showed the lowest fracture strength values among the groups. The elastic modulus of the supporting die structure is a significant factor in determining the fracture resistance of all-ceramic crowns. Using supporting die structures that have a low elastic modulus may be suitable for fracture strength tests, in order to accurately reflect clinical conditions.