Syftet med denna studie var att kliniskt utvärdera helkeramiska två- till femleds rekonstruktioner på implantat, samt att jämföra två olika keramiska system, Denzir® (DZ) och In-Ceram Zirconia® (InZ). Arton patienter behandlades med totalt 25 två- till femleds rekonstruktioner på implantat. Nio patienter fick rekonstruktioner utförda i DZ och nio patienter fick rekonstruktioner utförda i InZ. Rekonstruktionerna cementerades med zinkfosfatcement på preparerbara titandistanser. Rekonstruktionerna utvärderades efter 6- och 12 månader. Vid uppföljning efter 12 månader var alla 25 rekonstruktioner i funktion, inga hade frakturerat. Ytliga kohesiva, sk. chip-off, frakturer noterades däremot hos 6 av 18 patienter (8 av 25 rekonstruktioner). Nio led i DZ-gruppen (7 av 13 rekonstruktioner) och ett led i InZ-gruppen (1 av 12 rekonstruktioner) uppvisade chip-off frakturer. Skillnaden mellan de båda grupperna var statisktiskt signifikant (p< 0.01). Kantanslutningen bedömdes som utmärkt vid 34 stöd (56%) och acceptabel vid 27 stöd (44%). Resultat från denna 12 månaders uppföljning indikerar att helkeramiska två- till femleds rekonstruktioner på implantat kan övervägas som behandlingsalternativ. Vid jämförelse mellan de båda keramiska systemen är slutsatsen att DZ-systemet uppvisar oacceptabelt många frakturer i ytporslinet och därför inte kan rekommenderas för den typ av behandling som utvärderats här. Fortsatta studier och långtidsuppföljningar är nödvändiga innan ovan nämda material och teknik kan rekommenderas för allmänt bruk.

The purpose of this study was to evaluate the clinical performance of two to five-unit implant-supported all-ceramic reconstructions and to compare the results of two different all-ceramic systems, Denzir (DZ) and In-Ceram Zirconia (InZ). Eighteen patients were treated with a total of 25 two- to five-unit implant-supported reconstructions. Nine patients were given reconstructions of the DZ system and the other nine reconstructions of the InZ system.The reconstructions were cemented with zinc phosphate cement onto preparable titanium abutments and were evaluated after 6 and 12 months. At the 12-month follow-up, all reconstructions were in function; none had fractured. Superficial cohesive (chip-off) fractures were, however, observed in 6 of the 18 patients (8 of 25 reconstructions). Nine units in the DZ group (in 7 of 13 reconstructions) and one in the InZ group (1 of 12 reconstructions) had chip-off fractures. The difference between the two groups regarding frequency of chip-off fractures was statistically significant (P < 0.01). Marginal integrity was rated excellent at 34 abutments (56%) and acceptable at 27 (44%). Results from this 12-month trial suggest that all-ceramic implant-supported fixed partial dentures of two- to five-units may be considered a treatment alternative. When comparing the two ceramic systems under study, however, this study concludes that the DZ system exhibits an unacceptable amount of veneering porcelain fractures and thus cannot be recommended for the type of treatment evaluated in this trial. Further studies and long-term follow-ups must be performed before the materials and technique can be recommended for general use.

Reported clinical success rates of all-ceramic fixed partial dentures (FPDs) made of high-strength oxide ceramics range between 82.5% and 100%. The main cause of all-ceramic FPD failure is fracture in the connector area. There is, however, no consensus on what connector dimensions are adequate. The aim of this in-vitro study was, therefore, to compare the fracture strength of four-unit Y-TZP FPD cores designed with different connector diameters. A total of 40 four-unit FPD cores supported by end abutments and having two pontics were manufactured in Procera Zirconia. Five groups of FPD cores with connector dimensions of 2.0, 2.5, 3.0, 3.5 and 4.0 mm were produced. All FPD cores underwent a firing programme according to the manufacturer's recommendations for the veneering porcelain, a cyclic preload, thermocycling and finally, load until fracture. Fracture strength was significantly higher for each increase in connector diameter except for the 2.0-mm and 2.5-mm diameters where all fractures occurred during preload. All FPD cores fractured in the connector area. Within the limitations of this in-vitro study, a minimum diameter of 4.0 mm is recommended for all-ceramic zirconia-based FPDs with long spans or replacing molars. Clinical studies are, however, needed to determine adequate connector dimensions.

PURPOSE: The development of high-strength oxide ceramic materials has led to increased interest in all-ceramic fixed dental prostheses (FDPs). Success rates reported in clinical studies for all-ceramic FDPs based on high-strength oxide ceramic materials reportedly approach those of porcelain-fused-to-metal FDPs. These reconstructions, however, are still of limited size and have mainly concerned FDPs supported by natural teeth. The purpose of this study was to evaluate the clinical performance of multiunit all-ceramic FDPs supported by dental implants. MATERIALS AND METHODS: Ten patients received mandibular yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) FDPs manufactured according to the Cercon technique and supported by four Astra Tech implants. Nine patients received 10-unit FDPs and one patient received a 9-unit FDP. The FDPs were cemented with Panavia F 2.0 onto individually prepared titanium abutments. The FDPs were evaluated at baseline and after 12, 24, and 36 months. RESULTS: At the 3-year follow-up, all FDPs were in use, and all patients were fully satisfied with their treatment. None of the reconstructions had fractured. Superficial chip-off fractures of the veneering porcelain were, however, observed in nine patients (34 of 99 units, 34%). CONCLUSION: Results from this 3-year study suggest that implant-supported full-arch Y-TZP FDPs manufactured according to the Cercon technique should be viewed as a treatment alternative cautiously. A better understanding of the factors resulting in chip-off fractures is needed, together with longer follow-up studies involving larger numbers of patients, before the material and technique can be recommended for general use.

PURPOSE: The aim of this study was to evaluate the clinical performance of two- to five-unit implant-supported all-ceramic restorations and to compare the results of two different all-ceramic systems, Denzir (DZ) and In-Ceram Zirconia (InZ). MATERIALS AND METHODS: Eighteen patients were treated with a total of 25 two- to five-unit implant-supported fixed dental prostheses. Nine patients were given DZ system restorations and 9 were given InZ system restorations. The restorations were cemented with zinc phosphate cement onto customized titanium abutments and were evaluated after 1, 3, and 5 years. RESULTS: At the 5-year follow-up, all restorations were in function; none had fractured. However, superficial cohesive (chip-off) fractures were observed in 9 of 18 patients (11 of 25 restorations). Sixteen units in the DZ group (9 of 13 restorations) and 3 in the InZ group (2 of 12 restorations) had chip-off fractures. The difference between the two groups regarding frequency of chip-off fractures was statistically significant (P < .05 at the FDP level and P < .001 at the unit level). CONCLUSION: The results suggest that all-ceramic implant-supported fixed dental prostheses of two to five units may be considered a treatment alternative. The DZ system, however, exhibited an unacceptable amount of veneering porcelain fractures and thus cannot be recommended for the type of treatment evaluated in this trial. Poor compatibility or problems with the bond mechanisms between the veneer and framework could not explain the chip-off fractures. Stress distribution, as well as other factors concerning the veneering porcelain, need to be evaluated further.

Abstract Objectives: The aim of this study was to evaluate the effect of different types and design of zirconia frameworks as well as the effect of different veneering ceramics on the fracture strength of crowns. The importance of different abutment materials was also evaluated. Materials and methods: Eighty cores, 40 in a fully-sintered zirconia material and 40 in a pre-sintered zirconia material were made. Twenty cores of each material were made with a core of even thickness shape (ES) and 20 were made with a core with anatomical shape (AS). The cores were divided into subgroups and veneered with one of two different veneering ceramics: a porcelain and a glass-ceramic material. In total eight groups of 10 crowns were made. They were all cemented onto abutments made of resin. One extra group of 10 AS, pre-sintered zirconia cores veneered with glass-ceramic were made and cemented onto titanium abutments. All crowns underwent thermocycling and mechanical pre-load and were finally loaded until fracture. Results: AS crowns withstood significantly higher loads than ES crowns (P-value <0.001), and crowns with titanium abutments withstood significantly higher loads than crowns supported by abutments made of inlay pattern resin (P-value <0.001). Three types of fracture were noted: minor and major fracture of the veneering ceramic, and complete fracture through core and veneer. ES crowns showed significantly more major fractures of the veneering ceramic than AS crowns. Conclusions: This in vitro study indicates that the design of the core, as well as the abutment support, significantly influences fracture load and fracture mode of yttria-stabilized tetragonal zirconia polycrystals crowns.