Faculty Bibliography

This study evaluated the probability of survival (reliability) of platform-switched fixed dental prostheses (FDPs) cemented on different implant-abutment connection designs. Eighty-four-three-unit FDPs (molar pontic) were cemented on abutments connected to two implants of external or internal hexagon connection. Four groups (n = 21 each) were established: external hexagon connection and regular platform (ERC); external hexagon connection and switched platform (ESC); internal hexagon and regular platform (IRC); and internal hexagon and switched platform (ISC). Prostheses were subjected to step-stress accelerated life testing in water. Weibull curves and probability of survival for a mission of 100,000 cycles at 400 N (two-sided 90% CI) were calculated. The beta values of 0.22, 0.48, 0.50, and 1.25 for groups ERC, ESC, IRC, and ISC, respectively, indicated a limited role of fatigue in damage accumulation, except for group ISC. Survival decreased for both platform-switched groups (ESC: 74%, and ISC: 59%) compared with the regular matching platform counterparts (ERC: 95%, and IRC: 98%). Characteristic strength was higher only for ERC compared with ESC, but not different between internal connections. Failures chiefly involved the abutment screw. Platform switching decreased the probability of survival of FDPs on both external and internal connections. The absence in loss of characteristic strength observed in internal hexagon connections favor their use compared with platform-switched external hexagon connections.

OBJECTIVES: Narrow implants are indicated in areas of limited bone width or when grafting is nonviable. However, the reduction of implant diameter may compromise their performance. This study evaluated the reliability of several narrow implant systems under fatigue, after restored with single-unit crowns. MATERIALS AND METHODS: Narrow implant systems were divided (n = 18 each), as follows: Astra (ASC); BioHorizons (BSC); Straumann Roxolid (SNC), Intra-Lock (IMC), and Intra-Lock one-piece abutment (ILO). Maxillary central incisor crowns were cemented and subjected to step-stress accelerated life testing in water. Use level probability Weibull curves and reliability for a mission of 100,000 cycles at 130- and 180-N loads (90 % two-sided confidence intervals) were calculated. Scanning electron microscopy was used for fractography. RESULTS: Reliability for 100,000 cycles at 130 N was approximately 99 % in group ASC, approximately 99 % in BSC, approximately 96 % in SNC, approximately 99 % in IMC, and approximately 100 % in ILO. At 180 N, reliability of approximately 34 % resulted for the ASC group, approximately 91 % for BSC, approximately 53 % for SNC, approximately 70 % for IMC, and approximately 99 % for ILO. Abutment screw fracture was the main failure mode for all groups. CONCLUSIONS: Reliability was not different between systems for 100,000 cycles at the 130-N load. A significant decrease was observed at the 180-N load for ASC, SNC, and IMC, whereas it was maintained for BSC and ILO. CLINICAL RELEVANCE: The investigated narrow implants presented mechanical performance under fatigue that suggests their safe use as single crowns in the anterior region.

PURPOSE: The aim of this study was to evaluate the probability of survival of cemented and screwed three-unit implant-supported fixed dental prostheses (ISFDP) using different implant-abutment horizontal matching configurations (regular vs switching platforms). METHODS: One hundred and sixty-eight implants with internal hexagon connection (4 mm diameter, 10 mm length, Emfils; Colosso Evolution System, Itu, SP, Brazil) were selected for this study according to the horizontal implant-abutment matching configuration (regular or switching) and retention method and divided in four groups (n = 21 per group) as follows: 1) regular platform cemented (IRC); 2) or screw-retained (IRS); 3) switched-platform cemented (ISC); or 4) screw-retained (ISS). Regular and platform-switched abutments (Colosso evolution, 4 mm and 3.3 mm, respectively) were torqued, and 84 three-unit metal bridges were fabricated (first molar pontic). Implants were embedded in polymethyl-methacrylate resin and subjected to step-stress accelerated life testing in water. Weibull distribution was used to determine the probability of survival for a mission of 100,000 cycles at 400 N (90% two-sided confidence intervals). Polarized light and scanning electron microscopes were used for fractographic analysis. RESULTS: The beta values of 0.50, 1.19, 1.25, and 1.95 for groups IRC, IRS, ISC, and ISS respectively, indicated that fatigue accelerated the failure for all groups, except IRC. The cement-retained groups presented significantly higher probability of survival (I

This study evaluated color variability in the A hue between the VITA Classical (VITA Zahnfabrik) shade guide and four other VITA-coded ceramic shade guides using a Canon EOS 60D camera and software (Photoshop CC, Adobe). A total of 125 photographs were taken, 5 per shade tab for each of 5 shades (A1 to A4) from the following shade guides: VITA Classical (control), IPS e.max Ceram (Ivoclar Vivadent), IPS d.SIGN (Ivoclar Vivadent), Initial ZI (GC), and Creation CC (Creation Willi Geller). Photos were processed with Adobe Photoshop CC to allow standardized evaluation of hue, chroma, and value between shade tabs. None of the VITA-coded shade tabs fully matched the VITA Classical shade tab for hue, chroma, or value. The VITA-coded shade guides evaluated herein showed an overall unmatched shade in all tabs when compared with the control, suggesting that shade selection should be made using the guide produced by the manufacturer of the ceramic intended for the final restoration.

BACKGROUND: This study aimed to compare the histomorphometric and histological bone response to laser-sintered implants followed by resorbable-blasting media (RBM) process relative to standard machined/RBM surface treated implants. MATERIAL AND METHODS: Six male sheep (n=6) received 2 Ti-6Al-4V implants (1 per surface) in each side of the mandible for 6 weeks in vivo. The histomorphometric parameters bone-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated. RESULTS: Optical interferometry revealed higher Sa and Sq values for the laser-sintered/RBM surface in relation to standard/RBM implants. No significant differences in BIC were observed between the two groups (p>0.2), but significantly higher BAFO was observed for standard/RBM implants (p<0.01). CONCLUSIONS: The present study demonstrated that both surfaces were biocompatible and osseoconductive, and the combination of laser sintering and RBM has no advantage over the standard machined implants with subsequent RBM.

PURPOSE: To investigate the probability of survival of different implant-abutment connection designs in narrow versus standard-diameter implants supporting anterior crowns. MATERIALS AND METHODS: A total of 108 implants of either 3.5-mm or 4.0-mm diameter (narrow and standard, respectively) (10 mm in length, Implacil de Bortoli) were divided into six groups (n = 18 each) as follows: external hexagon 3.5 mm or 4.0 mm (EH3.5 or EH4.0), internal hexagon 3.5 mm or 4.0 mm (IH3.5 or IH4.0), and Morse taper 3.5 mm or 4.0 mm (MT3.5 or MT4.0). The corresponding abutments were screwed to the implants, and standardized maxillary central incisor metal crowns were cemented and subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and reliability for a mission of 50,000 and 100,000 cycles at 100 N and 150 N (90% 2-sided confidence intervals [CI]) were calculated. Polarized-light and scanning electron microscopes were used to assess the failure modes. RESULTS: The calculated reliability with 90% CI for a mission of 50,000 cycles at 100 N and 150 N showed that cumulative damage from the respective loads would lead to ~93% and ~18% implant-supported restoration survival in group EH3.5, ~99% and ~1% in group IH3.5, ~97% and ~89% in the MT3.5, ~100% and ~99% in the group EH4.0, ~100% and ~100% in group IH4.0, and ~99% and ~99% in group MT4.0. For the 100,000-cycle mission, the probability of survival estimated at 100 N and 150 N was, respectively: 0% for EH3.5 and IH3.5 at both load levels, ~96% and ~87% for the MT3.5, 100% and ~99% for EH4.0, 100% and ~99% for IH4.0, and 98% and ~92% for the MT4.0. CONCLUSION: A significant decrease in the probability of survival as a function of elapsed fatigue cycles and load increase was observed for narrow implants only with EH and IH implant-abutment connections, but not on Morse taper.

PURPOSE: To investigate the influence of atmospheric pressure plasma (APP) treatment on the microtensile dentin bond strength of two etch-and-rinse adhesive systems, after one week and one year of water storage, and additionally to observe the micromorphology of resin/dentin interfaces under scanning electronic microscopy (SEM). MATERIALS AND METHODS: The occlusal enamel was removed from third human molars to expose a flat dentin surface. The teeth were then randomly divided into six groups (n = 7), according to two adhesives (Optibond FL and XP-Bond) and three APP treatments (untreated dentin [control], APP application before or after acid etching). After performing the composite resin buildup on bonded dentin, the teeth were sectioned perpendicularly to the bonded interface to obtain beam-shaped specimens (cross-sectional area of ~0.9 mm2). The specimens were tested in tension until failure after one week and one year of water storage (1.0 mm/min rate). Bond strength data were analyzed by three-way ANOVA and Tukey's post-hoc test (alpha = 0.05%). Bonded beam specimens from each tooth were also prepared for interfacial SEM investigation. RESULTS: At one week, APP treatment applied after acid etching increased the dentin bond strength for XP Bond, while no effect was observed for Optibond FL. After one year, the bond strength of XP Bond decreased in groups where APP was applied after etching. The evaluation time did not influence the bond strength for Optibond FL. CONCLUSION: One-year evaluation did not show any sign of degradation of interfacial structures in any group. Application of APP to etched dentin combined with a two-step etch-and-rinse adhesive significantly increased bond strength at one week, but the effect was not stable after one year and was adhesive dependent.

Composite resins have been routinely used for posterior cavities due to a phasedown on amalgam as a restorative option. However, clinical problems related to polymerization shrinkage demands careful and specific techniques for placement of the composite layers. New low shrinkage composites are now marketed for bulk filling of cavities without the need of a traditional layering. With this new concept, the restoration can be built in one or two layers, depending on the classification of the bulk fill material. This article discusses and presents two alternative techniques using the low shrinkage composites, suggesting a called "amalgam-like sculpting technique," one using a flowable bulk fill and other a regular bulk fill material. Clinical cases illustrate these two alternatives compared with the layered technique. CLINICAL SIGNIFICANCE: New techniques using low shrinkage composites for bulk filling can provide a simpler technical approach for the clinician in sculpting and generating highly esthetic posterior composites.

OBJECTIVES: To evaluate the probability of survival and failure modes of implant-supported resin nanoceramic relative to metal-ceramic crowns. METHODS: Resin nanoceramic molar crowns (LU) (Lava Ultimate, 3M ESPE, USA) were milled and metal-ceramic (MC) (Co-Cr alloy, Wirobond C+, Bego, USA) with identical anatomy were fabricated (n=21). The metal coping and a burnout-resin veneer were created by CAD/CAM, using an abutment (Stealth-abutment, Bicon LLC, USA) and a milled crown from the LU group as models for porcelain hot-pressing (GC-Initial IQ-Press, GC, USA). Crowns were cemented, the implants (n=42, Bicon) embedded in acrylic-resin for mechanical testing, and subjected to single-load to fracture (SLF, n=3 each) for determination of step-stress profiles for accelerated-life testing in water (n=18 each). Weibull curves (50,000 cycles at 200N, 90% CI) were plotted. Weibull modulus (m) and characteristic strength (eta) were calculated and a contour plot used (m versus eta) for determining differences between groups. Fractography was performed in SEM and polarized-light microscopy. RESULTS: SLF mean values were 1871N (+/-54.03) for MC and 1748N (+/-50.71) for LU. Beta values were 0.11 for MC and 0.49 for LU. Weibull modulus was 9.56 and eta=1038.8N for LU, and m=4.57 and eta=945.42N for MC (p>0.10). Probability of survival (50,000 and 100,000 cycles at 200 and 300N) was 100% for LU and 99% for MC. Failures were cohesive within LU. In MC crowns, porcelain veneer fractures frequently extended to the supporting metal coping. CONCLUSION: Probability of survival was not different between crown materials, but failure modes differed. SIGNIFICANCE: In load bearing regions, similar reliability should be expected for metal ceramics, known as the gold standard, and resin nanoceramic crowns over implants. Failure modes involving porcelain veneer fracture and delamination in MC crowns are less likely to be successfully repaired compared to cohesive failures in resin nanoceramic material.