A customized zirconia abutment design combined with a CAD/CAM laminate veneer: a clinical report.

An alternative prosthetic treatment approach for single implants in the maxillary esthetic zone with an improper implant axis, limited interocclusal distance, inadequate abutment retention, and screw holes located at the labial surface is presented in this clinical report. The gingiva and soft tissues were contoured with provisional composite restorations to mimic the emergence profile of lateral incisors. Prefabricated zirconia abutments were customized with laminate veneer preparations by appropriate ceramic build-up with reference from the reshaped gingiva to avoid labiolingual overcontour. The laminate veneers were fabricated by computer-aided design/ computer-assisted manufacture to cover the screw hole of the angulated abutment at the labial surface. Preliminary results revealed improvement in esthetics; however, long-term clinical follow-up should be performed.

Microshear bond strength and finite element analysis of resin composite adhesion to press-on-metal ceramic for repair actions after various conditioning methods.

PURPOSE: This study evaluated the repair bond strength of differently surface-conditioned press-on-metal ceramic to repair composites and determined the location of the accumulated stresses by finite element analysis. MATERIALS AND METHODS: Press-on-metal ceramic disks (IPS InLine PoM, Ivoclar Vivadent) (N = 45, diameter: 3 mm, height: 2 mm) were randomly divided into 3 groups (n = 15 per group) and conditioned with one of the following methods: 9.5% hydrofluoric acid (HF) (Porcelain etch), tribochemical silica coating (TS) (CoJet), and an unconditioned group acted as the control (C). Each group was divided into three subgroups depending on the repair composite resins: a) Arabesk Top (V, a microhybrid; VOCO), b) Filtek Z250 (F, a hybrid;3M ESPE); c) Tetric EvoCeram (T, a nanohybrid; Ivoclar Vivadent) (n = 5 per subgroup). Repair composites disks (diameter: 1 mm, height: 1 mm) were photopolymerized on each ceramic block. Microshear bond strength (MSB) tests were performed (1 mm/min) and the obtained data were statistically analyzed using 2-way ANOVA and Tukey's post-hoc test (α = 0.05). Failure types were analyzed under SEM. Vickers indentation hardness, Young's modulus, and finite element analysis (FEA) were performed complementary to MSB tests to determine stress accumulation areas. RESULTS: MSB results were significantly affected by the surface conditioning methods (p = 0.0001), whereas the repair composite types did not show a significant effect (p = 0.108). The interaction terms between the repair composite and surface conditioning method were also statistically significant (p = 0.0001). The lowest MSB values (MPa ± SD) were obtained in the control group (V = 4 ± 0.8; F = 3.9 ± 0.7; T = 4.1 ± 0.7) (p < 0.05). While the group treated with T composite resulted in significantly lower MSB values for the HF group (T= 4.1 ± 0.8) compared to those of other composites (V = 8.1 ± 2.6; F = 7.6 ± 2.2) (p < 0.05), there were no significant differences when TS was used as a conditioning method (V = 5 ± 1.7; F = 4.7 ± 1; T = 6.2 ± 0.8) (p > 0.05). The control group presented exclusively adhesive failures. Cohesive failures in composite followed by mixed failure types were more common in HF and TS conditioned groups. Elasticity modulus of the composites were 22.9, 12.09, and 10.41 GPa for F, T, and V, respectively. Vickers hardness of the composites were 223, 232, and 375 HV for V, T, and F, respectively. Von Mises stresses in the FEA analysis for the V and T composites spread over a large area due to the low elastic modulus of the composite, whereas the F composite material accumulated more stresses at the bonded interface. CONCLUSION: Press-on-metal ceramic could best be repaired using tribochemical silica coating followed by silanization, regardless of the repair composite type in combination with their corresponding adhesive resins, providing that no cohesive ceramic failure was observed.

Effects of soldering and laser welding on bond strength of ceramic to metal.

STATEMENT OF PROBLEM: Welding or soldering of metal frameworks negatively affects the overall bond strength between the veneering ceramic and metal. PURPOSE: The purpose of this study was to evaluate the effect of soldering and laser-welding procedures on the bond strength between ceramic and metal. MATERIAL AND METHODS: Thirty Ni-based metal specimens (Wiron 99) (8 × 4 × 4 mm) were fabricated and divided into 3 groups; soldered (S), laser welded (L), and control (untreated cast alloy) (n=10). In S and L specimens, a notch (1 × 1.5 mm) was prepared longitudinally on the surface of each specimen and filled with compatible alloy (Wiron soldering rods and Wiroweld NC, respectively). Vickers hardness measurements were made after polishing the surfaces with a metallographic polishing kit. A veneering ceramic (VITA VMK 95) was vibrated, condensed in a mold, and fired on the metal frameworks. The specimens were sectioned in 2 axes to obtain nontrimmed bar specimens with a bonding area of approximately 1 mm². Forty bars per block were obtained. Each bar was subjected to microtensile bond strength (µTBS) testing with a crosshead speed of 1 mm/min. The µTBS data (MPa) were recorded, and SEM was used for failure analysis of the tested bars. The measurements were statistically analyzed using a 1-way ANOVA and Tamhane tests (α=.05). RESULTS: The mean differences in µTBS of veneering ceramic to soldered (10.4 ±2.4 MPa) and laser-welded (11.7 ±1.3 MPa) metal surfaces were not significantly different and were significantly lower than that of the cast alloy (25.4 ±3.6 MPa) (P<.05). The mean Vickers hardness of cast alloy was significantly higher (236 ±17 HV) than soldered (114 ±9 HV) and laser-welded groups (129 ±11 HV) (P<.05). CONCLUSIONS: Soldering and laser welding significantly decreased the µTBS of a veneering ceramic to a base metal alloy.

A preliminary report on short-term clinical outcomes of three-unit resin-bonded fixed prostheses using two adhesive cements and surface conditioning combinations.

PURPOSE: The aim of this study was to evaluate the survival rate of three-unit surface-retained, resin-bonded, metal-ceramic fixed dental prostheses (RBFDP) using two adhesive cements and two surface conditioning methods. MATERIALS AND METHODS: Between 2005 and 2009, a total of 58 patients (34 women, 24 men; mean age: 42.1 years) received 58 three-unit RBFDPs made of a nonprecious alloy (Wirocast Co-Cr). Restorations were cemented employing the following combinations: (1) alumina air abrasion-silane + Panavia F 2.0 (group A1), (2) tribochemical silica coating (CoJet)-silane + Panavia F 2.0 (group A2), (3) alumina air abrasion-silane + Super-Bond C and B (group B1), and (4) CoJet-silane + Super-Bond C and B (group B2). Teeth were conditioned using the adhesives of the cements accordingly. Adaptation, debonding, fracture, and crack and caries formation were considered for clinical evaluation. Data were collected at baseline, 6 months, and annually thereafter. Forty-eight RBFDPs were available for follow-up (mean: 20.3 months, minimum: 6 months, maximum: 42 months). RESULTS: The effect of cement type on the survival rate of RBFDPs was not significant (P > .05). The survival rate was also not significantly affected by the location (maxilla: 93.2%, mandible: 92.9%; P = .928). All experienced failures were observed within the first year after cementation. In total, four complete debondings were encountered (two in group A1, one in group A2, and one in group B1 at months 1, 3, 7, and 3, respectively). Group B2 did not result in any failures during the observation period. The failures were adhesive debondings between the metal surface and the cement. CONCLUSION: Early findings did not show significant differences between the cement and conditioning type combinations, with group B2 presenting no failures.

Reversal of reduced bond strength after bleaching.

This article investigated how the shear bond strength of a luting resin to dentin was affected by antioxidant treatment and delayed bonding after bleaching with carbamide peroxide. Using a lowspeed diamond saw, 40 flat dentin surfaces were prepared from freshly extracted human molars and divided into three bleaching groups (n = 10) and a control group (n = 10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent (10% sodium ascorbate), while Group 3 specimens were immersed in artificial saliva for one week after bleaching. Specimens in Group 4 were not bleached but were immersed in artificial saliva for one week before bonding. Forty ceramic blocks were prepared and luted to teeth using a dual-curing resin cement. The specimens were thermocycled and the shear bond strength tests were performed using a universal testing machine. Fracture analysis was performed using a scanning electron microscope. While the Group 1 samples demonstrated the lowest shear bond strengths (11.9 +/- 3 MPa) (p < 0.05), no significant differences were found among samples in Group 2 (26.3 +/- 7.1 MPa), Group 3 (20.7 +/- 6.5 MPa), and Group 4 (22.1 +/- 2.5 MPa) (p = 0.05).

Prosthetic rehabilitation of hemimandibular hyperplasia: five-year follow-up.

Hemimandibular hyperplasia is a rare asymmetrical mandibular malformation, characterized by enlargement of the condyle, the condylar neck, the ramus, and the body of the mandible. This condition results in laterognathia, dental articulation disorders, and functional defects. Therapy largely depends on the patient's age and the desired esthetic and functional results. This clinical report describes the prosthetic rehabilitation of a 50-year-old woman with hemimandibular hyperplasia. During the diagnostic phase, facial asymmetry was observed, as was the chin midline shifting to the unaffected side and three-dimensional enlargement of one side of the mandible, the condyle, the condylar neck, and the ramus. No biomechanical or functional problems were seen at a five-year follow-up visit, except for physiological wear to the artificial teeth.

Immediate provisional restoration fabrication for immediate implant loading using a modified technique: a clinical report.

This article describes the immediate fabrication and placement of a provisional restoration, using a modified method for impressionmaking. An impression was made before surgery and provisional acrylic temporary restorations with composite resin frameworks were prepared on the solid-screw implant abutments. This article demonstrates this simple method and discusses the benefits of immediate provisionalization after surgery.

Preliminary evaluation of titanium tetrafluoride as an alternative ceramic etchant to hydrofluoric acid.

PURPOSE: The etching of dental ceramics with a glassy matrix by means of hydrofluoric acid (HF) is highly effective and after the application of a silane coupling agent, a strong link between the adhesive and the ceramic is achieved. The purpose of this study was to investigate whether aqueous titanium tetrafluoride (TiF4) solution could be used as an alternative ceramic etchant or not. MATERIALS AND METHODS: Seventy lithia-based all-ceramic specimens (IPS Empress 2, Ivoclar Vivadent) (diameter: 4 mm, height: 4 mm) were prepared and ultrasonically cleaned for 15 min in ethanol and deionized water, then divided into 1 control and 4 experimental groups (n = 14/group). The control group was acid etched with 4.9% HF for 20 s as described by the manufacturer. The experimental groups were treated with 2.5% TiF4 solution for 60 s, 2.5% TiF4 solution for 120 s and 5% TiF4 solution for 60 s, as well as 5% TiF4 solution for 120 s. Seven of the ceramic specimens in each group were luted to the other seven by a dual-curing cement (Variolink II, Ivoclar Vivadent,) with silane application (Monobond-S). After storage of luted specimens in deionized water at 37 degrees C for 24 h, the specimens were embedded in plastic holders with cyanoacrylate, and the shear-bond strength (SBS) tests were performed with a Shimadzu universal testing machine at a crosshead speed of 0.5 mm/min. A one-way ANOVA and Bonferroni correction, followed by the Tukey test, were applied for statistical analysis. Scanning electron microscopic examination was performed to evaluate the pattern of debonding. RESULTS: Significantly higher SBS values (p 0.05). CONCLUSION: Aqueous TiF4 solution exhibited similar shear bond strength values in comparison to commonly used HF and can be considered as an alternative ceramic etchant within the limitations of this preliminary report.

Prosthetic rehabilitation of segmental odontomaxillary dysplasia: seven-year follow-up.

Segmental odontomaxillary dysplasia is an uncommon maxillofacial deformity. Clinically, overgrowth and maturation of the maxillary right or left posterior alveolus and the respective gingiva, lack of premolars, delayed eruption of the adjacent teeth, and malformed primary molars are observed. The purpose of this report was to describe the clinical and radiographic findings of a 47-year-old female with segmental odontomaxillary dysplasia and summarize the prosthetic rehabilitation with fixed and removable partial dentures. A 7-year follow-up did not reveal biomechanical or functional problems except the loss of the mandibular left central incisor and wear of the artificial teeth.

Evaluation of bond strength of various margin ceramics to a zirconia ceramic.

OBJECTIVE: This study evaluated the bond strengths of four different margin ceramics based on fluoroapatite and feldspath to a zirconia ceramic. METHODS: Zirconia cores (Zirconzahn) (N=28, n=7/margin ceramic group) were fabricated according to the manufacturers' instructions (diameter: 4mm; thickness: 2mm) and ultrasonically cleaned. Four different margin ceramics (thickness: 5mm) (Cerabien Zr, Noritake; Ceramco PFZ, Ceramco; e.max, Ivoclar Vivadent and Triceram, Dentaurum) were vibrated and condensed in a stainless steel mould and fired onto their zirconia cores. After trying the specimens in the mould for minor adjustments, they were again ultrasonically cleaned and embedded in PMMA. The specimens were stored in distilled water at 37 degrees C for 1 week and shear bond strength (MPa+/-S.D.) tests were performed in a universal testing machine (crosshead speed: 0.5mm/min). Failure modes were recorded under SEM. RESULTS: Significant effect of margin ceramic types were found on the bond strength values (P<0.05). The mean bond strength values of Ceramco margin ceramic to zirconia was significantly lower (25.4+/-4.5 MPa) (P<0.05) than those of Cerabien (31.6+/-6.4 MPa), e.max (35.9+/-8.4 MPa), and Triceram margin ceramic (38.8+/-7.1 MPa) systems. CONCLUSIONS: Margin ceramics, compatible with zirconia framework material tested in the present study, exhibited high bond strength values. Variations in thermal expansion coefficients might influence their bond strength values.

Effect of antioxidant treatment on bond strength of a luting resin to bleached enamel.

PURPOSE: The aim of this study was to comparatively investigate the effect of antioxidant treatment and delayed bonding after bleaching with carbamide peroxide on the shear bond strength (SBS) of a luting resin to enamel. MATERIALS AND METHODS: Forty flat enamel surfaces were prepared from freshly extracted human molars using a low speed diamond saw, then divided into three bleaching groups (n=10/group) and a control group (n=10). Group 1 consisted of specimens bonded immediately after bleaching. Group 2 specimens were treated with an antioxidant agent, 10% sodium ascorbate, while Group 3 specimens were immersed in artificial saliva for 1 week after bleaching. Specimens in Group 4 were not bleached, but immersed in artificial saliva for 1 week before bonding. Forty ceramic blocks (Empress 2, Ivoclar) were prepared and luted to teeth using a dual-curing resin cement (Variolink II, Ivoclar). The specimens were thermocycled and the SBS tests were performed using a universal testing machine (crosshead speed: 0.5mm/min). Fracture analysis of the bonded surfaces was done using a scanning electron microscope. Statistical analysis was carried out by Kruskall-Wallis and Mann-Whitney U-tests. RESULTS: While the samples that were immediately bonded after bleaching (Group I) demonstrated significantly lower shear bond strengths and 10% sodium ascorbate group (Group II) demonstrated significantly higher bond strengths than control group samples (p<0.05), no significant differences were found among delayed bonded group and control group (p>0.05). CONCLUSION: Using sodium ascorbate with a concentration of 10% may be reliable for reversing the compromised bond strength.