Ceramic veneers outperform composite laminate veneers after 10 years
Ceramic veneers on maxillary anterior teeth perform significantly better after 10 years than composite indirect laminate veneers with respect to survival rate and quality of surviving restorations. The findings are from a study published in the July issue of Journal of Dentistry.
Authors designed a randomized clinical trial to measure the 10-year performance of maxillary anterior laminate veneers made from particulate-filled composite and ceramic in a split-mouth design. Restoration survival was the trial’s primary outcome, and quality of survival was the secondary outcome.
A total of 11 patients (8 women, 3 men) ranging in age from 20 through 69 years (mean age, 54.5 years) received 24 indirect resin composite veneers and 24 ceramic laminate veneers from 2008 through 2011. A total of 20 restorations were placed on central incisors, 18 on lateral incisors, and 10 on canines.
One technician made veneers for all teeth, which were isolated using a split rubber dam technique. Labial surfaces were axially reduced by 0.3 through 0.5 millimeters, and an incisal overlap of 1 through 1.5 mm was prepared on all cases. A 0.5-mm chamfer finish line was created to maintain periodontal health, and a shallow chamfered marginal finish line extended interproximally to hide the restoration margins up to the contact area.
The technician used the IPS Empress (Ivoclar Vivadent) layering and lost wax technique to make glass ceramic veneers according to the manufacturer’s instructions. A cutback of 0.2 through 0.8 mm was performed after wax-up to allow for layering of the veneering ceramic. The layering technique was used to make indirect composite laminate veneers, which were heat-and photo-polymerized according to the manufacturer’s instructions. Contour strips were placed interproximally to perform a smooth restoration outline in the cervical area.
The technician luted the laminate veneers by applying a photo-polymerizing resin composite cement to the inner surface of the laminates. Veneers were photo-polymerized with a light-emitting diode lamp of at least 800 milliwatts per square centimeter for 3 seconds at the buccal surface. Excess composite at the margins was removed with brushes, scalers, and dental floss. Buccal, oral, and proximal surfaces were polymerized for 40 more seconds.
Authors evaluated all restorations at baseline and every year thereafter using modified criteria from the US Public Health Service and compared them using the Mann-Whitney U test. Authors used Kaplan-Meier and log-rank tests to measure the overall survival rate in relation to observation time. Observation time ranged from 89 months through 120 months (mean, 97 months).
Authors found the cumulative chance of survival after 10 years of the indirect resin composite and ceramic veneers was 75% (se 3, 8%) and 100%, respectively (P = .013). They noted 6 absolute failures in the indirect resin composite group (3 from debonding, 3 from fracture). Among the remaining 42 veneers, authors noted significant differences in color matching (Mann-Whitney U = 324, P = .002). Authors also observed significantly more rough surfaces and plaque adhesion (Mann-Whitney U = 444, P = .000) in the resin composite laminate veneer group. Authors noted significantly more internal fractures without intervention (Mann-Whitney U = 292, P = .028) and restoration wear (Mann-Whitney U = 303, P = .014) in the indirect composite group.
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Ideal emergence profiles for implant-supported restorations
Dentists who combine analog impression and digital scanning techniques with computer-aided design and computer-aided manufacturing technology can develop a prosthetically driven emergence profile for implant-supported restorations. The 6-step technique is detailed in an article published online October 1 in The Journal of Prosthetic Dentistry.
Authors developed the technique to develop an esthetic, predictable, and definitive emergence profile for implant-supported restorations.
In step 1, dentists examine and radiograph the implant and obtain a conventional impression and digital scan with an open tray impression coping and scan body. Dentists then pour a stone die and replicate the soft tissue with a gingival polyvinyl siloxane material and use a surgical blade to sculpt it into a definitive emergence profile.
In step 2, dentists use a Ti- (titanium) insert and block out resin to obtain a custom healing abutment from the modified model. The abutment would be placed after administrating local anesthetic. Step 3 requires dentists to make a new scan that captures changes made to the silicone material and add it to the initial scan as a gingiva mask in the Chairside Economical Restoration of Esthetic Ceramics (CEREC) software. Step 4 requires dentists to reduce soft-tissue margins in the gingiva mask folder to achieve an emergence profile to match the custom healing abutment. In step 5, dentists design and mill a screw-retained monolithic crown from a lithium disilicate block. Ceramic material is crystallized and glazed. Dentists then bond the monolithic crown to the Ti-insert with a chemically polymerized opaque resin cement. After the healing period, the final step requires dentists to remove the custom healing abutment and deliver the screw-retained restoration with optimal soft-tissue support.
Authors noted several advantages to their technique. The length of healing abutments can be ignored. Sculpting soft tissue is no longer necessary after using the custom healing abutment. Custom anatomic abutments can overcome the limitations of stock abutments, which cannot approximate all contours during healing. The procedure takes less chair time, and computer-aided design and computer-aided manufacturing technology allows dentists to make a custom abutment or screw-retained implant crown with a definitive emergence profile. The technique eliminates laboratory costs and eliminates laboratory errors when the gingival mask can be designed while fabricating the definitive restoration. Reducing repeated disconnection of components from the implant also minimizes the loss of peri-implant bone and soft tissue.
“This technique can be used immediately after implant placement,” the authors concluded, “allowing the custom abutment to support peri-implant tissue and facilitating access to the implant during the restorative phase.”
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Cleaning methods can reduce surface area for bonding to Y-TZP
Cleaning surfaces of tribochemically silica-coated yttria-stabilized zirconium dioxide (Y-TZP) with air-water spray or an ultrasonic bath lowers the amount of silica deposited on the surface and available for bonding. The finding is from a study published in the November issue of Dental Materials.
Authors designed the study with a 2-fold purpose: to measure the effect of cleaning methods on silica distribution on Y-TZP surfaces after tribochemical silica coating and to measure the effect of different cleaning methods on aging of the silane-silica mediated bond strength between Y-TZP and resin cement.
Authors milled Y-TZP slabs measuring 10- X 6- X 2 millimeters from computer-aided design and computer-aided manufacturing blocks using a custom mill file. The slabs were cleaned in acetone for 10 minutes, then dried with compressed air. One surface of each specimen was air-abraded with 30-micrometer silica coated alumina particles. Authors then divided the slabs into 3 groups: no cleaning (NC), cleaning with oil-free air-water spray for 5 seconds (AW), and cleaning with an ultrasonic bath in water for 10 minutes (UB).
For bonding procedures, authors used Y-TZP slabs that were tribochemically silica-coated and cleaned according to the NC, AW, or UB groups. Authors applied a ceramic primer on the zirconia surface in 1 coat with a microbrush, left undisturbed for 1 minute and air-dried for 5 seconds. Authors built microshear specimens on the Y-TZP surface by positioning a silicone mold on the surface and filling it with resin-based cement. They light-cured the resin cement using a polywave light-emitting diode curing unit with a mean irradiance of 1,100 microwatts per square centimeter for 40 seconds from the top of the silicone mold. Two resin cement cylinders were built on each zirconia slab, and the silicone molds were removed after 5 minutes. Authors split the 20 slabs from each group into 2 aging conditions: 24 hours or 3 months plus thermocycling.
For testing, authors used a 0.2-mm diameter wire at a crosshead speed of 0.5 mm per minute to apply a shear load at the joint between the resin cement cylinder and the zirconia surface until failure occurred. Authors calculated the microshear bond strength for each resin cylinder based on the load at fracture and the adhesive joint dimensions.
Authors used the Shapiro-Wilk test to measure data normality, and one-way analysis of variance and post hoc Tukey tests to measure the effects of cleaning protocols on silica (Si) distribution. They used 2-way analysis of variance and post hoc Tukey tests to measure the effect of cleaning protocol, aging method and interactions between them and microshear bond strength values. Reliability of bond strength after each cleaning treatment was analyzed using Weibull analysis.
Authors found that the cleaning method significantly affected the amount of silica (Si) on the tribochemically coated zirconia surface (P < .001). They noted the lowest amount of Si when the zirconia surface was cleaned by an ultrasonic bath in distilled water for 10 minutes. Scanning electron microscopic images showed higher amounts of Si in the control Y-TZP surface than surfaces cleaned with either air-water spray or an ultrasonic bath.
Authors found that cleaning the surface of Y-TZP after tribochemical silica coating with air-water spray compromised the silica-mediated bonding to Y-TZP immediately and after aging. They also found that the tested cleaning methods compromised the chemical interaction between the silica coverage of the blasted zirconia and a silane primer. Cleaning method (P < .001) and aging (P < .001) were significant for bond strength values, but bond strength to the tribochemically coated Y-TZP did not show reliable performance over time.
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Good looks, integrity, intelligence linked to dental esthetics
Dental esthetics affect views of a man’s integrity, intelligence, and social skills more than a woman’s, but their effect on facial attractiveness is neutral or negative for men and women in need of treatment. The findings are from a study published in the October issue of American Journal of Orthodontics & Dentofacial Orthopedics.
Authors designed the study to measure how quantified dental attractiveness affects facial attractiveness (aim 1) and to see how different levels of quantified facial and dental attractiveness of models influenced raters’ opinions of their social attractiveness (aim 2).
Authors used 48 facial images of 18- to 30-year-old white men and women from The Ohio State University for the study. Each person provided 1 photo with a closed-lip smile (no teeth) and one with an open-lip smile and exposed teeth. Authors used composite images of female and male models with 3 different levels of background facial attractiveness (unattractive, average, and attractive) and 4 levels of dental attractiveness based on the Index of Orthodontic Treatment Need. A total of 15 full- and part-time university faculty with a least 10 years’ experience rated the images, then sorted them into Index of Orthodontic Treatment Need levels of 1, 5, 7, or 10. A rating of 1 indicated no need, a rating of 5 through 7 indicated a borderline need, and a rating of 10 indicated a clear need. Authors then used Photoshop (Adobe) to layer the sorted intraoral images on 24 open-lip smiling images of male and female models at all 3 levels of attractiveness.
A total of 68 people were recruited on campus away from the medical center to serve as raters. Raters were white, 18 to 30 years old, and not dentists or dental students. Authors randomized 72 images (24 open-lip, 24 closed-lip, and 50% repeats for reliability), then showed them on a computer screen about 2 feet away for 8 seconds. Responses were recorded on a 100-millimeter visual analog scale (VAS) in which 0 equals unattractive and 100 equals attractive. The open-lip VAS score minus the closed-lip VAS was calculated as influence of teeth on attractiveness.
Authors used 36 photos to measure how different levels of quantified background facial and dental attractiveness of models influenced raters’ opinions of the models’ social attractiveness. Raters were given 40 seconds to answer a survey of 9 questions for each image about integrity (honest), social (friendly, extroverted, high social class, compliant, popular, fun, kind) and intellectual (intelligent) dimensions.
Of the 67 raters used to measure aim 1, 50 were women and 17 were men. Of the 65 raters used for aim 2, 49 were women and 16 were men. The mean age of raters was 21.7 years. Interrater reliability for aims 1 and 2 was fair to excellent. Analysis of variance showed significant 3-way interactions for model, sex, background facial attractiveness, and dental attractiveness for both aims (P < .0001 for aim 1; P < .005 for aim 2.)
Authors found the greatest impact for female raters generally was poor dental esthetics for attractive models. Declining dental esthetics affected unattractive faces less among men, whereas average and attractive faces were more affected. The attractive group most affected for women when orthodontic treatment need was greatest.
Overall, women rated as more attractive than men. Average female faces were most affected by poor dental esthetics. For men, teeth had more effect as background facial attractiveness increased. The opposite was true for women. For men, dental attractiveness had the most significant effects on social and intellectual attractiveness in average and attractive groups. Average female and male faces had the most social judgments significantly affected by teeth. The effect of dental attractiveness on facial attractiveness and social and intellectual attractiveness depended on dental attractiveness level, background facial attractiveness, and model’s sex.
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How to choose the right cases for Icon treatment and tips for patient success
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The consulting editor for JADA+ Scan — Cosmetic/Esthetic is Luiz Meirelles DDS, MS, Ph.D., Assistant Professor in the Division of Restorative and Prosthetic Dentistry, The Ohio State University College of Dentistry. |
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