Fifteen-year outcome of three-unit fixed dental prostheses made from monolithic lithium disilicate ceramic.

OBJECTIVES: The purpose of this prospective study was to evaluate the clinical long-term outcome over 15 or more years of crown-retained fixed dental prostheses (FDPs) made from a lithium disilicate ceramic (IPS e.max Press, Ivoclar Vivadent AG). METHODS: Thirty-six three-unit FDPs replacing anterior (16%) and posterior (84%) teeth were inserted in 28 patients. Abutment teeth were prepared following a standardized protocol. The size of the proximal connector of the FDPs was 12 mm² (anterior) or 16 mm² (posterior). FDPs were cemented either conventionally with glass-ionomer cement (n = 19) or adhesively with composite resin (n = 17). The following parameters were evaluated at baseline, 6 months after cementation and then annually (at abutment and contralateral teeth): probing pocket depth, plaque index, bleeding on probing, and tooth vitality. RESULTS: Three FDPs were defined as drop-outs. The mean observation period of the remaining 33 FDPs was 167 months (range: 79-225 months). The survival rate (survival being defined as FDPs remaining in place either with or without complications) according to Kaplan-Meier was 48.6% after 15 years. The success rate (success being defined as free of complications and remaining unchanged) was 30.9% after 15 years. CONCLUSIONS: Fatigue and crack propagation caused by clinical aging in monolithic lithium disilicate ceramics seem to take considerable time, as shown by the presented survival and success rates after 15 years. Further long-term studies are necessary to evaluate the reliability of FDPs made from other all-ceramic materials over a period of 15 or more years.

Influence of bonding surface and bonding methods on the fracture resistance and survival rate of full-coverage occlusal veneers made from lithium disilicate ceramic after cyclic loading.

OBJECTIVES: The purpose of this laboratory study was to evaluate the influence of bonding method and type of dental bonding surface on fracture resistance and survival rate of resin bonded occlusal veneers made from lithium disilicate ceramic after cyclic loading. METHODS: Fourty-eight extracted molars were divided into three groups (N=16) depending on the preparation: within enamel, within dentin/enamel or within enamel/composite resin filling. Lithium disilicate occlussal veneers were fabricated with a fissure-cusp thickness of 0.3-0.6mm. Restorations were etched (5% HF), silanated and adhesively luted using a dual-curing luting composite resin. Test groups were divided into two subgroups, one using a only a self-etching primer, the other additionally etching the enamel with phosphoric acid. After water storage (37°C; 21d) and thermocycling (7500 cycles; 5-55°C), specimens were subjected to dynamic loading in a chewing simulator (600,000 cycles; 10kg/2Hz). Surviving specimens were loaded until fracture using a universal testing machine. RESULTS: All specimens survived artificial aging, several specimens showed some damage. ANOVA revealed that enamel etching provided statistically significantly (p≤0.05) higher fracture resistance than self-etching when bonding to enamel and dentin. Self-etching provided statistically significant (p≤0.05) higher fracture resistance for the enamel-composite group than for the enamel group. Enamel etching provided statistically significant (p≤0.05) higher fracture resistance for the enamel and dentin group than for groups enamel and enamel-composite. SIGNIFICANCE: Etching enamel improved the fracture resistance of occlusal veneers when bonding to dentin and enamel and increased the survival rate when bonding to enamel.

Implant Placement under Existing Removable Dental Prostheses and the Effect on Follow-Up and Prosthetic Maintenance.

PURPOSE: The aim of this prospective clinical study was to compare the maintenance interventions required for solely implant-retained overdentures (I-OD) with that of overdentures retained by a combination of telescopic crowns and implants (T/I-OD). MATERIALS AND METHODS: The participants in this study were 22 patients who initially presented either with a removable complete denture (n = 11) or with an overdenture retained by 1 to 2 telescopic crowns on natural teeth (n = 11). Subsequently, the total number of abutments was increased to 5 to 6 (maxilla) or 4 to 5 (mandible) by placing implants in strategically advantageous regions, generating two distinct groups: I-OD and T/I-OD. Ball attachments were connected to the implants and integrated into the existing denture. The maintenance aspects were analyzed according to the type of treatment (preventive, biological, and technical) and to the severity of treatment (minimal, moderate, and extensive). RESULTS: During a mean observation time of 6.5 years, the tooth survival rate was 89% (T/I-OD) and the implant survival rate 100% (both groups). The survival rates of the overdentures ranged from 90.9% (I-OD) to 100% (T/I-OD). A mean number of 0.6 (I-ODs) and 2.0 (T/I-OD) treatments were performed for biological reasons; and 8.2 (I-ODs) and 9.6 (T/I-OD) for technical reasons, per patient, during the observation time. From biological aspects, significantly more extensive maintenance was found to be necessary in the T/I-OD group than in the I-OD group. CONCLUSIONS: The therapeutic concept of implant placement under existing prostheses was promising when performed in indicated cases.

Influence of attachment design and material on the retention of resin-bonded attachments.

OBJECTIVES: The purpose of this laboratory study was to evaluate the influence of the attachment design and material on the retention of resin-bonded attachments (RBAs) before and after dynamic loading. MATERIALS AND METHODS: Forty-eight caries-free human premolars were prepared for RBAs fabricated either from a CoCr alloy or from zirconia ceramic. Specimens were divided into three groups (n = 16 each). Two groups had a standard attachment design for alloys (group M made from a CoCr alloy and group Z1 made from zirconia ceramic). The third group had an attachment design optimized for zirconia ceramic (group Z2 made from zirconia ceramic). Attachments were bonded to the acid-etched enamel of the premolars using a phosphate monomer containing adhesive resin. Subgroups of eight specimens each were either debonded using a tensile force in a universal testing machine at a cross-head speed of 2 mm/min (S) or were exposed to dynamic loading with 50 N over 1200,000 loading cycles in a chewing simulator prior to debonding (D). RESULTS: There were no significant differences in the initial failure loads of groups. With the exception of subgroup Z1-D, all specimens survived the dynamic loading. Statistical analysis showed that dynamic loading caused a significant decrease of failure loads in group Z1. In contrast, subgroup Z2-D exhibited significantly higher failure loads compared to the subgroup Z1-D. CONCLUSIONS: The results suggest that zirconia RBAs fabricated with an optimized attachment design may be a valid clinical alternative to metal RBAs. CLINICAL RELEVANCE: Clinical data on the long-term potential of zirconia RBAs is required before these restorations can be recommended for general use.

Ten-year outcome of zirconia ceramic cantilever resin-bonded fixed dental prostheses and the influence of the reasons for missing incisors.

OBJECTIVES: This clinical study evaluated the long-term outcome and survival rate of all-ceramic cantilever resin-bonded fixed dental prostheses (RBFDPs) made of zirconia-ceramic with a single-retainer design to replace missing incisors. In addition, whether the reason for missing incisors has an influence on the longevity of RBFDPs was analyzed. MATERIALS AND METHODS: One hundred and eight zirconia ceramic cantilever RBFDPs were provided for 87 patients. Seventy-five RBFDPs replaced maxillary incisors and 33 mandibular incisors. The restorations were subsequently categorized into 3 groups according to the reasons for missing teeth (congenitally missing, trauma and other reasons). The patients were followed up annually, and the restorations were assessed for function and aesthetics. The mean observation time of the RBFDPs was 92.2±33months. RESULTS: Six debondings and 1 loss of restoration were recorded. The lost restoration was removed at the patient's request after a small chip occurred on the mesial edge of the pontic. Three of the 6 observed debondings were caused by traumatic incidents. All debonded RBFDPs were rebonded successfully with no further complications. Zirconia ceramic RBFDPs yielded a 10-year survival rate of 98.2% and a success rate of 92.0%. CONCLUSIONS: Anterior zirconia ceramic cantilever RBFDPs provided excellent clinical longevity. The reasons for missing incisors did not influence the longevity of the cantilever RBFDPs.

Influence of restoration thickness and dental bonding surface on the fracture resistance of full-coverage occlusal veneers made from lithium disilicate ceramic.

OBJECTIVES: The purpose of this in-vitro study was to evaluate the influence of ceramic thickness and type of dental bonding surface on the fracture resistance of non-retentive full-coverage adhesively retained occlusal veneers made from lithium disilicate ceramic. METHODS: Seventy-two extracted molars were divided into three test groups (N=24) depending on the location of the occlusal veneer preparation: solely within enamel, within enamel and dentin or within enamel and an occlusal composite resin filling. For each test group, occlusal all-ceramic restorations were fabricated from lithium disilicate ceramic blocks (IPS e.max CAD) in three subgroups with different thicknesses ranging from 0.3 to 0.7mm in the fissures and from 0.6 to 1.0mm at the cusps. The veneers were etched (5% HF), silanated and adhesively luted using a self etching primer and a composite luting resin (Multilink Primer A/B and Multilink Automix). After water storage at 37°C for 3 days and thermal cycling for 7500 cycles at 5-55°C, specimens were subjected to dynamic loading in a chewing simulator with 600,000 loading cycles at 10kg combined with thermal cycling. Unfractured specimens were loaded until fracture using a universal testing machine. Statistical analysis was performed using Kruskal-Wallis and Wilcoxon tests with Bonferroni-Holm correction for multiple testing. RESULTS: Only specimens in the group with the thickest dimension (0.7mm in fissure, 1.0mm at cusp) survived cyclic loading without any damage. Survival rates in the remaining subgroups ranged from 50 to 100% for surviving with some damage and from 12.5 to 75% for surviving without any damage. Medians of final fracture resistance ranged from 610 to 3390N. In groups with smaller ceramic thickness, luting to dentin or composite provided statistically significant (p≤0.05) higher fracture resistance than luting to enamel only. The thickness of the occlual ceramic veneers had a statistically significant (p≤0.05) influence on fracture resistance. SIGNIFICANCE: The results suggest to use a thickness of 0.7-1mm for non-retentive full-coverage adhesively retained occlusal lithium disilicate ceramic restorations.

Survival of anterior cantilevered all-ceramic resin-bonded fixed dental prostheses made from zirconia ceramic.

OBJECTIVES: This study evaluated the clinical outcome of all-ceramic resin-bonded fixed dental prostheses (RBFDPs) with a cantilevered single-retainer design made from zirconia ceramic. METHODS: Forty-two anterior RBFDPs with a cantilevered single-retainer design were made from yttrium oxide-stabilized zirconium oxide ceramic. RBFDPs were inserted using Panavia 21 TC as luting agent after air-abrasion of the ceramic bonding surface. RESULTS: During a mean observation time of 61.8 months two debondings occurred. Both RBFDPs were rebonded using Panavia 21 TC and are still in function. A caries lesion was detected at one abutment tooth during recall and was treated with a composite filling. Therefore, the overall six-year failure-free rate according to Kaplan-Meier was 91.1%. If only debonding was defined as failure the survival rate increased to 95.2%. Since all RBFDPs are still in function the overall survival rate was 100% after six years. CONCLUSIONS: Cantilevered zirconia ceramic RBFDPs showed promising results within the observation period. CLINICAL SIGNIFICANCE: Single-retainer resin-bonded fixed dental prostheses made from zirconia ceramic show very good mid-term clinical survival rates. They should therefore be considered as a viable treatment alternative for the replacement of single missing anterior teeth especially as compared to an implant therapy.

All-ceramic resin-bonded fixed dental prostheses: treatment planning, clinical procedures, and outcome.

Single-retainer resin-bonded fixed dental prostheses (RBFDPs) present a minimally invasive treatment option as an alternative to implant-retained restorations in the esthetic zone. Advantages such as applicability to juvenile patients who do not come into consideration for implant therapy, and highly predictable and esthetic results make them a valuable treatment modality. This article outlines the treatment procedures with an all-ceramic RBFDP and reviews the existing data on the clinical outcome of this prosthetic therapy. The materials used for fabrication and insertion of the RBFDPs as well as the current scientific data are discussed.

Clinical performance of cantilevered fixed dental prostheses abutments in the shortened dental arch.

OBJECTIVES: This article is part of a randomized clinical trial on different treatments in the shortened dental arch (SDA). It focused on the abutment tooth prognosis with cantilevered fixed dental prostheses (CFDPs). METHODS: Sixty-two patients with a bilaterally SDA up to the first or second premolar in the mandible or maxilla were evaluated. In 57 of 124 quadrants, second premolars were replaced by a CFDP (cantilever group). In the remaining 67 quadrants, a natural second premolar was present and thus no need for a CFDP was given (non-cantilever group). Patients were recalled annually up to 5 years. RESULTS: The mean observation period was 56.3 months (min. 3.0, max. 76.2, SD 16.1). Kaplan-Meier survival rates concerning tooth loss and tooth fracture were 93.9%/94.0% in the cantilever group and 91.9%/92.8% in the non-cantilever group. Differences between both groups were not significant. The survival rate concerning loss of retention of CFDP retainers was 92.1% in the cantilever group. CONCLUSION: After 5 years of clinical service, CFDPs for the replacement of the second premolar showed no negative impact on the abutment tooth prognosis. CLINICAL SIGNIFICANCE: Cantilevered fixed dental prostheses present a viable treatment option in the shortened dental arch without compromising the medium-term abutment tooth prognosis.

Randomized clinical trial on single retainer all-ceramic resin-bonded fixed partial dentures: Influence of the bonding system after up to 55 months.

OBJECTIVES: This study evaluated the clinical outcome of all-ceramic resin-bonded fixed partial dentures (RBFPDs) with a cantilevered single-retainer design. METHODS: Thirty anterior zirconia ceramic RBFPDs were inserted using either a phosphate monomer containing resin (Panavia 21 TC; N=16) or an adhesive bonding system with a phosphoric acid acrylate primer (Multilink-Automix with Metal/Zirconia primer; N=14). RESULTS: During a mean observation time of 41.7 months one debonding occurred in each group. Both RBFPDs could be rebonded successfully resulting in a three-year survival rate of 100%. CONCLUSION: Independent of the bonding system cantilevered zirconia ceramic RBFPDs showed promising results during the first three years. CLINICAL SIGNIFICANCE: Single-retainer zirconia ceramic RBFPD present an alternative treatment option offering good aesthetics, a minimal invasive preparation, a high biocompatibility and can even be used to treat juvenile patients who do not yet come into consideration for implant placement. No significant influence of the bonding system used was detected so far.

Ten-year outcome of three-unit fixed dental prostheses made from monolithic lithium disilicate ceramic.

BACKGROUND: The authors conducted a prospective study to evaluate the long-term outcome of crown-retained fixed dental prostheses (FDPs) made from monolithic lithium disilicate ceramic (IPS e.max Press, Ivoclar Vivadent, Schaan, Liechtenstein). METHODS: Faculty dentists at the Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Germany, placed 36 three-unit FDPs in 28 patients to replace six anterior and 30 posterior teeth. The proximal connector size (height and width) was 4 × 3 millimeters for anterior FDPs and 4 × 4 mm for posterior FDPs. FDPs were cemented either conventionally with glass ionomer cement (n = 19) or adhesively with resin-based composite (n = 17). Patients made annual recall visits. RESULTS: The mean (standard deviation) observation period was 121 (12.8) months. FDPs' survival rate (survival being defined as remaining in place either with or without complications) was 100 percent after five years and 87.9 percent after 10 years, and their success rate (success being defined as remaining unchanged and free of complications) was 91.1 percent after five years and 69.8 percent after 10 years. The cementation method did not affect the outcome. CONCLUSION: Three-unit FDPs made from monolithic lithium disilicate ceramic showed five- and 10-year survival and success rates that were similar to those of conventional metal-ceramic FDPs. CLINICAL IMPLICATIONS: If the manufacturer's recommendations are followed, three-unit FDPs made from monolithic lithium disilicate ceramic may be a safe alternative to metal-ceramic FDPs regardless of the cementation method used.

Ten-year survival of anterior all-ceramic resin-bonded fixed dental prostheses.

PURPOSE: To evaluate the long-term outcome of all-ceramic resin-bonded fixed dental prostheses (RBFDPs) made with a two-retainer design or a cantilever single-retainer design. MATERIALS AND METHODS: Overall, 38 anterior RBFDPs were made from a glass-infiltrated alumina ceramic (In-Ceram). Sixteen RBFDPs had a two-retainer design, while 22 RBFDPs had a cantilever single-retainer design. Phosphate monomer containing luting agents were used either after silica coating and silanation or after air-abrasion only. The mean observation time in the two-retainer group was 120.2 months and in the single-retainer group 111.1 months. RESULTS: No restoration debonded. In the two-retainer group unilateral and bilateral fractures of the connectors occurred. In the case of unilateral fracture, the pontic remained in situ as a cantilever RBFDP for several years. In the single-retainer group, only one FDP fractured and was lost 48 months after insertion. The 10-year survival rate was 73.9% in the two-retainer group and 94.4% in the single-retainer group. When unilateral fracture of a FDP was taken as a criterion for failure, the 10-year survival rate decreased to 67.3% in the two-retainer group. CONCLUSION: Cantilever all-ceramic RBFDPs are an adequate alternative to two-retainer RBFDPs.