June 8, 2018
Desensitizing gel for bleach-induced tooth sensitivity will not harm whitening
Desensitizing gel made with 5% potassium nitrate and 5% glutaraldehyde can lower the risk and severity of dental sensitivity without harming whitening results. The finding is from a study published in the April issue of The Journal of the American Dental Association.
Authors designed the triple-blind clinical trial to measure the risk and intensity of bleaching-induced tooth sensitivity (TS) by using a desensitizing gel made with potassium nitrate and glutaraldehyde. The study was a split-mouth, placebo-controlled, randomly controlled trial with an equal allocation ratio.
A total of 42 study participants were at least 18 years old and did not report any type of TS.
Researchers used desensitizing gel made with 5% potassium nitrate and 5% glutaraldehyde in a hydroxyethylcellulose gel. The placebo was the same but without the desensitizing agents.
All patients received the same bleaching treatment. Researchers first isolated the gingival tissue of bleached teeth, then light-cured them for 10 seconds. They placed a light-cured gingival barrier between the central incisors to prevent contact between the gels.
Operators placed the gel made with 5% glutaraldehyde and 5% potassium nitrate in 1 side of the maxillary arch and placebo gel in the other side, and then left them undisturbed for 10 minutes. The gel was applied on enamel, not dentin.
Operators agitated each dental surface with a rubber cup mounted in a slow-speed hand piece for 10 seconds, and then removed the gels with an aspirator tip and water rinsing. They bleached both sides of the patients’ maxillary arches with a 35% hydrogen peroxide gel in 3 separate 15-minute applications in accordance with the manufacturer’s directions. Researchers refreshed the in-office bleaching agent every 15 minutes during the 45-minute application period. They performed 2 bleaching sessions 1 week apart.
Researchers used a numeric rating scale and a visual analog scale to measure TS intensity for each side of the maxillary arch. They used a digital spectrophotometer and a value-oriented shade guide to measure color.
Researchers recorded color at baseline, 1 week after the first bleaching session, 1 week after the second bleaching session, and 1 month after the end of the bleaching treatment. Because researchers waited a week after each session to measure color, dehydration and demineralization were not a factor.
The researchers compared the absolute risk of developing TS for both groups with the use of the McNemar test. They calculated the relative risk, the 95% confidence interval (CI) for the effect size and the number needed to treat. They also compared bleaching-induced TS intensity (numeric rating scale data) of the 2 groups at each assessment points with the Wilcoxon signed rank test.
Researchers found a statistically significant difference (P < .0001) in the risk of developing bleaching-induced TS between the desensitizing gel group (31.7%, 95% CI, 19.6 to 46.9) and the placebo group (70.7%; 95% CI, 55.5 to 82.3%). They also noted a statistically significant difference (P < .001) in pain intensity in the first 24 hours. They found no statistically significant difference in color change between teeth treated with desensitizing gel or placebo.
Read the original article here.
Consulting Editor: Luiz Meirelles DDS, MS, PhD
Predictive power of tooth color on young adult life just a shade above average
Lightness, chroma, and translucency are not major predictors of psychosocial aspects of young adult life, according to a study published online October 31 in Journal of Prosthodontics.
Authors designed the study to see how the color of patients’ teeth affected the social and emotional aspects of their lives. They included 134 students (65% female), aged 19 to 28 years (median, 21 years; interquartile range, 20-22 years), from the University of Rijeka, Croatia, in their research.
Authors chose the maxillary right central incisor as the reference tooth and measured its color in all participants using a spectrophotometer. All participants had 6 intact maxillary anterior teeth.
Authors based the oral health–related quality of life (OHQoL) as it relates to dental esthetics on validated Croation versions of the following: the Oral Health Impact Profile, the Orofacial Esthetic Scale (OES), the Psychosocial Impact of Dental Aesthetics Questionnaire, the Orofacial Appearance, and the Psychosocial Impact (PSI) dimensions of Oral Health Impact Profile.
Those dimensions comprised 21 items scored on a 5-point Likert-type scale with values ranging from 0 = never to 4 = very frequently. The OES features 8 items with answers based on a 5-point Likert-type scale with values ranging from 1 = completely unsatisfied to 5 = completely satisfied. The OES features 1 dimension that evaluates satisfaction with smile esthetics. The Psychosocial Impact of Dental Aesthetics Questionnaire features 23 items with answers on a 5-point Likert-type scale with values ranging from 0 = no impact to 4=maximal impact.
Authors grouped items into 4 dimensions: dental self-confidence (range, 0-24), social impact (range, 0-32), psychological impact (range, 0-32), and esthetic concern (range, 0-12).
Authors noted no differences in terms of lightness and translucency between sexes. Women reported higher PSI and psychological impact (PI) scores than men did (P < .05). Lightness, chroma, and translucency did not correlate with either OHRQoL or age (r < 0.132, P > .05).
Increased age led to an increase in satisfaction with smile esthetics (measured with OES) and decreased the frequency of PSI. Women were more likely to be influenced by psychological effects (measured with PSI and PI). Age and sex accounted for less than 6% variability in esthetic satisfaction and OHRQoL, while regression models had a low predictive power.
“Tooth color may affect self-confidence and social integration,” the authors noted. “This is a likely reason why younger individuals require tooth whitening more often and are more demanding when evaluating tooth color. … it is quite likely that perception of smile esthetics is influenced by the media and the inability to define other elements of facial attraction.”
Read the original article here.
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Flexural strength of monolithic zirconia is something to chew on
Monolithic zirconia at thicknesses of 0.8 millimeters and 1.3 mm can withstand masticatory forces, and the flexural strength increases with thickness. Airborne particle abrasion increased the flexural strength of monolithic zirconia, but grinding and polishing had no effect. The findings are from a study published online October 14 in Journal of Prosthetic Dentistry.
Authors designed the study to measure how thickness and surface modifications affected monolithic zirconia. They fabricated 10 millimeter–diameter monolithic zirconia disks with thicknesses of 0.8 mm and 1.3 mm. They made 21 disks for each thickness and split the 2 groups into 3 subgroups of 7 according to the surface treatments received: untreated control groups (C), airborne particle abrasion groups prepared by using 50-micrometers aluminum oxide particles at a pressure of 4 kilopascals and a distance of 10 mm (A), and ground groups that were ground to the respective thickness using a diamond rotary instrument (G).
Authors conducted the biaxial flexure test using a piston-on-3-balls technique in a universal testing machine. Three hardened 3.2-mm–diameter steel balls were evenly spaced around a support circle with a 6-mm radius. Flexural loading was applied with a 1.4-mm diameter steel cylinder and centered on the disk at a crosshead speed of 0.5 mm per minute until fracture.
Authors then used electron microscopic images of 3 fractured disks from each group to analyze the fracture mode. They evaluated cross-sections of the specimens at ×10,000 magnification to observe crack patterns, grain size and shape, and porosity.
Authors found a statistically significant difference related to surface treatments in the 0.8-mm groups (P < .05). The 08A specimens showed significantly higher flexural strength than 08C and 08G specimens (P < .05). No statistically significant difference was found between the flexural strength of the 08A and 08C specimens (P > .05).
In the 1.3-mm groups, the 13A specimens revealed significantly higher flexural strength than the 13C and 13G specimens (P < .05). No statistically significant difference was found between the flexural strength of the 13C and 13G specimens (P > .05).
A comparison of the control groups showed that 13C had significantly higher flexural strength than 08C (P < .05). A comparison of the airborne-particle abrasion groups indicated that 13A had significantly higher flexural strength than 08A (P < .05). In the ground groups, 13G had significantly higher flexural strength than 08G (P < .05).
“This study showed that increasing the thickness from 0.8 mm to 1.3 mm significantly changes flexural strength, regardless of surface treatment,” the authors concluded. In addition, “The mean flexural strength of 0.8-mm and 1.3-mm thick monolithic zirconia was greater than reported masticatory forces, and airborne-particle abrasion increased the flexural strength of monolithic zirconia. Finally, grinding did not affect flexural strength if subsequently polished.”
Read the original article here.
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A great smile can brighten up any summer get-together or vacation for your patients. There’s no time like the present to give them the information they need to brighten their smiles. The comprehensive brochure, “Tooth Whitening for a Brighter Smile” will give your patients options for in-office whitening, whitening toothpastes, and home-use whiteners.
- The merits and side effects of each whitening option.
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The 6-page brochure is available in packs of 50 from the ADA Catalog. A sample can be viewed here. To order, call 1-800-947-4746 or go to adacatalog.org. The title is available personalized as well. Readers who use the code 18412E before June 29 can save 15 percent on all ADA Catalog products.
ADA CE Online courses on bleaching and sensitivity
Do your patients say they want whiter teeth but without the painful side effects from over-bleaching? Check out these courses on ADA CE Online and be better prepared for your patients’ esthetic needs.
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JADA+ Specialty Scans and JADA+ Scans
JADA+ Specialty Scans and JADA+ Scans are quarterly newsletters updating dentists on the latest research in selected specialties and disciplines in dentistry. ADA Publishing and the consulting editors from the represented specialties and disciplines aggregate and summarize research from previously published materials, each item attributed to its publication of origin. JADA+ Scan specialties and disciplines include endodontics, oral pathology, orthodontics, pediatric dentistry, periodontics, prosthodontics, radiology, cosmetic/esthetic and osseointegration. The ADA has engaged the specialty organizations in these areas as well as its own Science Institute and Division of Legal Affairs to assist with these newsletters. View past issues here.
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