Injectable technique for direct provisional restoration.

OBJECTIVE: New technique describes an alternative treatment modality of making direct provisional restoration. CLINICAL CONSIDERATIONS: A preoperative wax-up should be fabricated, followed by fabrication of a transparent polyvinyl siloxane (VPS) matrix in a clear plastic prefabricated tray with retentive holes. After the tray is separated from the model, two additional holes will be made through the tray and the VPS for injecting and venting of the temporary resin. After the teeth are prepared and the separating medium applied to them, the resin should be injected into the entrance hole using the provided auto-mix cartilage tip. The flow of the resin around the preparation can be observed through the clear mold and once the resin starts to extrude from the exit hole. It is necessary to block the exit hole with a finger while continuing to inject. This will increase the pressure inside the mold and improve marginal adaptation. Before complete polymerization, the matrix is removed. The provisional restorations are removed from the matrix and contoured, adjusted, and polished. CONCLUSION: This technique will help the clinicians to enhance the quality of the provisional restorations, to prevent entrapment of bubbles, improve marginal precision and prevent seating error. CLINICAL SIGNIFICANCE: This study described a novel technique for constructing a direct provisional restoration by injecting bis-acryl temporary resin into a matrix that is already seated over the prepared tooth.

Novel Approach to Managing Malsequenced and Malpositioned Immediately Placed Implants in the Esthetic Zone.

Esthetic implant therapy can be challenging in the anterior maxilla, and meticulous treatment is often required to deliver optimal esthetics. Close collaboration between surgical and prosthetic team members using the novel approach of prosthetic crown lengthening helped camouflage a shallow implant platform location, providing the proper gingival frame for esthetic restorations. This case report presents an interdisciplinary approach that included ridge augmentation, second-stage crown lengthening, and prosthetic soft tissue manipulation to address an implant placed too shallow in the alveolus of an extraction socket.

A retrospective survey on long-term survival of posterior zirconia and porcelain-fused-to-metal crowns in private practice.

OBJECTIVES: This retrospective survey assessed the clinical survival of zirconia-based crowns (PFZ) and conventional porcelain- fused-to-metal (PFM) crowns on posterior teeth in private practice. METHOD AND MATERIALS: A print survey of 13 private practitioners was conducted to assess the long-term survival of previously placed full-coverage crowns. The practitioners reported a total of 2,182 premolar (n = 881) and molar (n = 1,301) full-coverage single crowns, 1,102 PFZ and 1,080 PFM, fabricated by one dental laboratory (Cusp, Boston) and followed over 7.4 years. All post-cementation complications (eg, porcelain fractures and chippings) were recorded as failures. In the PFZ group, one veneering porcelain (CZR, Kuraray Noritake) was used in combination with three coping systems (Lava, 3M ESPE; Procera, Nobelbiocare; Katana, Kuraray Noritake). Kaplan-Meier survival analysis was used for statistical analyses. RESULTS: The probability of survival of posterior crowns investigated over the period of study (7.4 years) was 99.3% for PFM and 99.2% for PFZ restorations. There was no statistically significant difference (P = .614) between PFZ and PFM groups. In the PFZ group, probability of survival was 97.7% for Lava, 100% for Procera, and 99.5% for Katana. There were no statistically significant differences (P = .34) between the three PFZ systems or the location of the crowns (premolar or molar; P = .454). CONCLUSION: PFZ crowns fabricated with CZR and three commercial zirconia coping systems revealed excellent long-term success rates. Survival times and survival probabilities of posterior PFZ crowns did not differ from PFM crowns and were independent of type of coping system and location (molar or premolar teeth).

Clinical efficacy of veneered zirconium dioxide-based posterior partial fixed dental prostheses: five-year results.

STATEMENT OF PROBLEM: In recent years, zirconium dioxide-based partial fixed dental prostheses (FDP) have been suggested as an alternative treatment to traditional metal ceramic FDPs. However, clinical studies evaluating their longevity and related complications are limited. PURPOSE: The purpose of this cohort clinical study was to assess the efficacy of zirconium dioxide-based posterior 3-unit FDPs. MATERIAL AND METHODS: Twenty 3-unit posterior FDPs (Lava) were placed in 16 participants missing a second premolar or a first molar. All participants met specific inclusion and exclusion criteria and provided informed consent. All teeth were prepared in a standardized manner: occlusal reduction of 1.5 to 2 mm; axial reduction of 1 to 1.5 mm; a 1.0 mm 360-degree rounded shoulder placed 0.5 mm subgingivally on the facial aspect and supragingivally on the lingual aspect on sound tooth structure; and rounded internal line angles. Definitive impressions were made with vinyl polysiloxane impression material. Frameworks were fabricated by using computer-aided design and computer-aided manufacturing (CAD/CAM) technology with a uniform retainer thickness of 0.6 mm and a minimal connector surface area of 9 mm(2). Restorations were luted with resin-modified glass ionomer cement (Rely-X Luting). Participants were recalled at 2 weeks, 6 months, and 12 months, and thereafter, annually for up to 60 months. Clinical fracture measurements, marginal discoloration, marginal adaptation, radiographic proximal recurrent caries, and periapical pathoses were assessed over time by using modified Ryge criteria. The probability distributions of these variables were calculated for the baseline data and for the recall data. An analysis of survival was made by using the Kaplan-Meier method. RESULTS: Eighteen FDPs were clinically evaluated at 5 years and 1 at 48 months. Fifteen were rated Alpha for fracture measurements, and 2 were rated Bravo (minor chipping of veneering porcelain and not requiring restoration replacement). Two were rated Charlie (major chipping of veneering porcelain and requiring restoration replacement). Eighteen FDPs were rated Alpha for marginal integrity, and 1 rated Bravo. All restorations were rated Alpha for marginal discoloration. One participant experienced root fracture after 60 months, while another was treated surgically for a periapical pathosis on an endodontically treated abutment. CONCLUSIONS: Zirconium dioxide-based posterior 3-unit FDPs performed well after 5 years of service.

Bond strength of different veneering ceramics to zirconia and their susceptibility to thermocycling.

PURPOSE: To evaluate the bond strength of recently developed feldspathic veneering ceramics to zirconium-oxide ceramic core material (Y-TZP). In addition, the effect of thermocycling on the bond strength was investigated. METHODS: 90 square Lava framework Y-TZP specimens were randomly assigned to three groups (n = 30) and veneered with one of the three zirconia veneering ceramics Cerabien ZR (CZR), GC Initial (GCI), or Lava Ceram (LC). 30 additional metal-ceramic specimens served as the control (VO). 15 specimens per group were stored in a saline solution for 3 days. To test the durability of the bond, 15 specimens per group were thermocycled for 10,000 cycles between 5 degrees to 60 degrees C with a 15-second dwell time. Shear strength was tested with an Instron universal testing system. A two-way ANOVA model and Tukey's HSD were applied for statistical analyses (alpha = 0.05). RESULTS: The different material combinations revealed significantly different shear bond strength values (CZR > GCI > LC > VO). All veneering ceramic/zirconia combinations showed significantly higher bond strength than the metal-ceramic control VO. Bond strength values were not affected by thermocycling, except for CZR, which had significantly higher bond strength after thermocycling. Microscopic evaluation of failure modes revealed 100% cohesive failures in the veneering ceramic for all specimens.

Comparison of marginal fit between all-porcelain margin versus alumina-supported margin on Procera Alumina crowns.

PURPOSE: Procera Alumina crowns are widely used; however, the effect of crown margin design on marginal fit is unknown. This study measured and compared the precision of fit of Procera Alumina crowns with two crown margin designs: all-porcelain versus alumina-supported margins. MATERIALS AND METHODS: Sixteen noncarious extracted human premolars were prepared for Procera((R)) Alumina crowns with an internally rounded shoulder preparation. Impressions were made from all teeth, and master dies were poured with type IV dental stone. The specimens were randomly divided into two groups. Procera Alumina crowns were fabricated: eight crowns with circumferential porcelain-butt (all-porcelain) margins and eight crowns with coping (alumina-supported) margins (control). Precision of fit was measured at six points on each crown with a profilometer (profile projector). The data were statistically analyzed with an independent-samples t-test (alpha < 0.05). RESULTS: The mean marginal gap size (microm) of coping margins was 68.07 +/- 16.08 and of porcelain-butt margins was 101.29 +/- 43.71. There was no statistically significant difference (p= 0.065) of the marginal gap size between coping margins and porcelain-butt margins. CONCLUSION: The results of this study demonstrate that there was no statistically significant difference in the marginal fit of coping and porcelain-butt margins. Both margin designs are within clinically acceptable ranges. Therefore, clinicians may choose to use a coping margin, as it is less labor intensive and requires less time for fabrication, unless there is a specific high esthetic need for a porcelain-butt margin.

Influence of cementation technique on fracture strength and leakage of alumina all-ceramic crowns after cyclic loading.

OBJECTIVE: To compare in vitro the influence of 3 cementation techniques on leakage and fracture strength of alumina all-ceramic crowns after cyclic loading in an artificial chewing simulator. METHOD AND MATERIALS: Forty-eight extracted molars were mounted in a way that simulates natural tooth mobility. Crowns (Procera Alumina, Nobel Biocare) were fabricated and inserted with either conventional cementation with zinc phosphate cement without pretreatment (group ZOP); cementation with a universal adhesive resin cement without pretreatment (group HYB); or adhesive bonding with composite resin after pretreatment of the tooth (dentin bonding agent) and the crown (airborne-particle abrasion and a special ceramic priming agent containing adhesive monomers that bond to metal-oxide ceramics) (group ADH). All specimens were stored in artificial saliva and subjected to 1.2 million load cycles in a dual-axis chewing simulator (Willytec). Eight specimens per group were subjected to compressive load until failure, while the remaining 8 specimens were stained and sectioned for measuring of dye penetration. One-way ANOVA and Tukey HSD were used for statistical analyses (alpha = .05). RESULTS: Cementation techniques were significantly different (P = .009) in regard to mean load at failure. Fracture strength was significantly greater for ADH (mean load at fracture, 2,782 +/- 419 N) as compared to HYB (1,980 +/- 270 N) or ZOP (1,788 +/- 242 N). All groups differed significantly for leakage values (P < .001), with ADH showing the lowest mean leakage (0.04 +/- 0.07 mm), followed by HYB (0.96 +/- 0.16 mm) and ZOP (2.44 +/- 0.19 mm). CONCLUSION: Cementation technique affects fracture strength and leakage of all-ceramic molar crowns. Fracture strengths were well above natural chewing forces for all cementation methods. However, adhesive bonding significantly increased fracture strength and improved marginal seal of alumina crowns.

Influence of surface treatment and simulated aging on bond strengths of luting agents to zirconia.

OBJECTIVE: To evaluate short- and long-term shear bond strengths of 4 luting agents to zirconia following different surface treatments. METHOD AND MATERIALS: A total of 320 ceramic specimens fabricated from a commercial zirconium oxide ceramic (Lava) were randomly divided into 4 groups: left untreated (NOT), airborne-particle abraded (SND), Rocatec tribochemical silica/silane coated (ROC), or ground and polished (GRD). Resin composite cylinders were bonded to the zirconia specimens with resin composite luting agent RelyX ARC (ARC), universal adhesive resin composite RelyX Unicem (UNI), adhesive-phosphate-monomer-containing resin composite Panavia F (PAN), or the hybrid glass-ionomer cement RelyX Luting (LUT). Subgroups of 10 specimens were stored in distilled water (37 degrees C) for 3 days (ST) or stored for 180 days and thermocycled for 12,000 cycles (LT/TC) before shear bond strength was tested. Statistical analyses included Kruskal-Wallis and Wilcoxon 2-sample rank sum test (alpha = .01). RESULTS: Short-term shear bond strengths were higher with ROC than with SND, which were both greater than GRD or NOT. UNI revealed higher shear bond strengths than PAN, ARC, and LUT. LT/TC significantly decreased shear bond strength values. GRD and NOT produced the lowest shear bond strengths. SND and ROC significantly increased bond strength. ROC generally yielded the highest long-term shear bond strength, especially with UNI, PAN, or ARC. These were similar to SND and PAN, which revealed the highest long-term shear bond strengths. CONCLUSIONS: Surface treatment, luting agent, and storage conditions significantly influence shear bond strengths to zirconia. Artificial aging significantly reduces shear bond strengths. Airborne-particle abrasion combined with a resin composite containing adhesive phosphate monomers or tribochemical silica/silane coating combined with any of the tested resin composite luting agents provides superior long-term shear bond strength values.

Precision of fit of two margin designs for metal-ceramic crowns.

STATEMENT OF PROBLEM: Although metal-ceramic restorations are widely used, there is a lack of information about how the fit is affected by margin designs. PURPOSE: This study measured and compared the precision of fit of metal-ceramic crowns with two margin designs. MATERIAL AND METHODS: Thirty-two extracted human premolar teeth were prepared for complete-coverage restorations with an internally rounded shoulder preparation. Impressions were made from all teeth, and master dies were poured with improved stone type V. MC crowns were fabricated with a porcelain-butt margin on the buccal aspect (n = 32) and a feather-edge metal margin on the lingual aspect (n = 32), which served as a control group. Precision of fit was measured three times at the mid-buccal and mid-lingual margins of each crown with a profilometer. The data were statistically analyzed with the paired t-test (alpha < .05). RESULTS: Mean marginal gap size of porcelain-butt margins was 27.93 microm (+/-15.84) and of feather-edge metal margins 42.43 microm (+/-24.12). The marginal gap size of feather-edge metal margins was statistically significantly greater than that of porcelain-butt margins (p = 0.0045). CONCLUSION: The marginal fit of porcelain-butt margins was significantly better than that of feather-edge metal margins. CLINICAL IMPLICATIONS: Porcelain-butt margins in this study had a better marginal fit than feather-edge metal margins, and thus have given clinicians evidence to prefer the use of porcelain-butt margins.

Efficacy of a computerized shade selection system in matching the shade of anterior metal-ceramic crowns--a pilot study.

OBJECTIVE: The purpose of this study was to determine whether anterior crowns fabricated using a computerized shade selection system (ShadeScan, Cynovad) (experimental procedure) match adjacent teeth better than anterior crowns fabricated using conventional shade prescription and clinical slides (control). METHOD AND MATERIALS: Five subjects who required a crown to restore a maxillary central incisor were selected. Two metal-ceramic crowns were fabricated for each incisor, 1 using the experimental procedure and 1 using the control method. The shade selection method to be used for the first and second crowns was randomly assigned. The duration of each procedure was recorded. Each restoration was tried-in in a double-blind manner and evaluated for its level of match to adjacent teeth using modified Ryge criteria. Data were analyzed within each subject using descriptive statistics and paired t test (alpha = .05). RESULTS: In 40% of the cases, both procedures did equally well. In the remaining 60% of the cases the control procedure (two-thirds of the cases) performed better than the experimental procedure (one-third of the cases). Duration of the control procedure was 14.4 +/- 5 minutes, and the experimental procedure was 5.2 +/- 3.3 minutes. A paired t test showed the difference was significant (P = .0045). CONCLUSION: The level of matching of crowns fabricated with the ShadeScan system was not different from crowns fabricated using the control. However, it took significantly less time to record the shade with the ShadeScan system.

The efficacy of posterior three-unit zirconium-oxide-based ceramic fixed partial dental prostheses: a prospective clinical pilot study.

STATEMENT OF PROBLEM: Although zirconium-oxide-based restorations for fixed partial denture prostheses (FPDPs) are available for use, clinical studies evaluating their longevity and related complications have not been published. PURPOSE: The aim of this pilot clinical study was to assess the efficacy of zirconia-based posterior 3-unit FPDPs. MATERIAL AND METHODS: Twenty 3-unit posterior FPDPs (Lava) were placed in 16 subjects who were missing a second premolar or a first molar, met specific inclusion and exclusion criteria, and provided informed consent. All teeth were prepared in a standardized manner: occlusal reduction of 1.5 to 2 mm; axial reduction of 1 to 1.5 mm; a 1.0-mm, 360-degree rounded shoulder placed 0.5 mm subgingivally on the facial aspect and supragingivally on the lingual aspect on sound tooth structure; and rounded internal line angles. Impressions were made with vinyl polysiloxane (Express) impression material. Frameworks were fabricated using a computer-aided design/computer-assisted manufacturing technique with a retainer thickness of 0.6 mm, and a minimal connector surface area of 9 mm(2). Restorations were luted with resin-modified glass-ionomer cement (Rely X luting). Recall appointments were made after 2 weeks and 6, 12, 18, 24, and 36 months. Clinical fracture resistance, marginal discoloration, marginal adaptation, radiographic proximal recurrent decay, and periapical pathoses were assessed over time using modified Ryge criteria. The probability distributions of these variables were calculated for the baseline data as well as for recall data. RESULTS: Mean follow-up was 31.2 months. Fifteen restorations were rated Alpha in all measured parameters. Minor chipping of veneering porcelain was detected in 5 restorations rated Bravo for clinical fracture resistance and Alpha for all other assessed parameters. One restoration was rated Bravo in terms of marginal integrity at 36 months. CONCLUSIONS: Zirconia-based posterior 3-unit FPDPs performed well after short-term service.

In vitro fracture strength of teeth restored with different all-ceramic crown systems.

STATEMENT OF PROBLEM: There is insufficient knowledge of the strength of all-ceramic crowns bonded to natural teeth to warrant the use of all-ceramic crowns in place of metal-ceramic crowns. PURPOSE: The purpose of this study was to evaluate and compare fracture resistance of crowns made of 3 different types of 2 all-ceramic crown systems-0.4-mm and 0.6-mm aluminum oxide coping crowns and zirconia ceramic coping crowns-and metal-ceramic crowns. MATERIAL AND METHODS: Forty intact, noncarious human maxillary central incisors were divided into 4 groups (n=10): Group MCC (control), metal-ceramic crown (JRVT High Noble Alloy); Group AC4, crown with 0.4-mm aluminum oxide coping (Procera AllCeram); Group AC6, crown with 0.6-mm aluminum oxide coping (Procera AllCeram); and Group ZC6, crown with 0.6-mm zirconia ceramic coping (Procera AllZirkon). Teeth were prepared for complete-coverage all-ceramic crowns so that a final dimension of 5.5 +/- 0.5 mm was achieved incisocervically, mesiodistally, and faciolingually. A 1.0-mm deep shoulder finish line was used with a rounded internal line angle. All restorations were treated with bonding agent (Clearfil SE Bond) and luted with phosphate-monomer-modified adhesive cement (Panavia 21). Fracture strength was tested with a universal testing machine at a crosshead speed of 2 mm per minute with an angle of 30 degrees to the long axis of the tooth after restorations were stored in 100% relative humidity of a normal saline solution for 7 days. The mode of fracture was examined visually. Means were calculated and analyzed with 1-way ANOVA and Tukey's HSD (alpha=.05). RESULTS: The means of fracture strength were: Group MCC, 405 +/- 130 N; Group AC4, 447 +/- 123 N; Group AC6, 476 +/- 174 N; and Group ZC6, 381 +/- 166 N. There was no significant difference between groups ( P =.501). The mode of failure for all specimens was fracture of the natural tooth. CONCLUSIONS: There was no significant difference in the fracture strength of the teeth restored with all-ceramic crowns with 0.4- and 0.6-mm aluminum oxide copings, 0.6-mm zirconia ceramic copings, and metal ceramic crowns.

Long-term resin bond to densely sintered aluminum oxide ceramic.

BACKGROUND: Densely sintered aluminium oxide ceramic is a popular material for ceramic copings and all-ceramic restorations. A strong, predictable, and long-term durable resin bond is key for long-term clinical success of bonded alumina-based restorations. PURPOSE: The purpose of this study was to measure and compare in vitro shear bond strengths of three resin cements with and without their corresponding silane coupling/bonding agent to air particle- abraded densely sintered aluminum oxide ceramic after long-term water storage and thermocycling. MATERIALS AND METHODS: Composite resin cylinders were bonded to air particle-abraded samples of densely sintered aluminum oxide ceramic with Noribond DC (Noritake Dental Supply, Inc., Aichi, Japan), Panavia 21 EX (Kuraray, Osaka, Japan), and Variolink II (Ivoclar Vivadent, Schaan, Liechtenstein), which were used with and without their corresponding silane coupling and bonding agents (n = 15). All specimens (N = 90) were stored for 180 days in water and subjected to repeated thermocycling for a total of 12,000 cycles before shear bond strength was tested. Data were analyzed with the Kruskal-Wallis test and the Wilcoxon two-sample rank sum test at the 5% level of significance. RESULTS: Most groups had no or only minimal bond strength to densely sintered alumina after simulated aging. Panavia had the highest bond strength without silane/bonding agent application. Noribond with its silane/bonding agent revealed the highest overall bond strength, which was significantly greater than that of either Variolink or Panavia after silanization. CONCLUSIONS: Resin cements revealed significantly different bond strengths, and the use of silane coupling and bonding agents had various effects on the resin bond to pure densely sintered alumina. CLINICAL SIGNIFICANCE: Selection of the proper cement/bonding system is fundamental to clinical long-term success of bonded alumina-based restorations. Noribond with its bonding agent and ceramic primer seem to fulfill these requirements under clinically relevant testing conditions.

Prótesis fija estética en dientes anteriores

Principios artísticos y científicos aplicados a la odontología estética. Diagnóstico y planificación del tratamiento de problemas estéticos. Cambio de coronas incorrectas. Coronas de metal-cerámica. Coronas totalmente de cerámica y conorans laminadas. Comunicación con el laboratorio dental: procedimientos de prueba y selección del color. Tratamiento de los tejidos en la zona anterosuperior. Impresiones de la dentición anterior. Estética gingival