Research and Education A comparison of the fracture resistance of premolars without a ferrule with different post systems

The Journal of Prosthetic Dentistry

Available online 19 November 2019

The Journal of Prosthetic Dentistry

Abstract

Statement of problem

Which type of post improves the performance of endodontically treated mandibular premolars without a ferrule remains unclear.

Purpose

The purpose of this in vitro study was to compare the restoration of endodontically treated mandibular premolars without a ferrule by using different post systems.

Material and methods

Thirty extracted mandibular premolars were endodontically treated, and their crowns removed. They were divided into 3 groups with different post systems (n=10): zirconia ceramic posts (ZRPs), fiber posts (FPs), and bundled glass fiber-reinforced composite resin posts (GTPs). After post placement and core fabrication, computer-aided design and computer-aided manufacture (CAD-CAM) lithium disilicate crowns were cemented. The specimens were subjected to thermocycling and mastication simulation before a fracture test in a universal testing machine. The maximum load at which the fracture occurred was recorded, and the fractured specimens were examined by using an optical microscope. The data were analyzed for statistical differences with a 1-way ANOVA and the Tukey honestly significant difference post hoc test (α=.05).

Results

No statistically significant difference in fracture strength was found among the groups (P=.970). From the light microscopy examination, catastrophic failure was observed in all specimens, and there was no failure of the ceramic crowns.

Conclusions

Based on the findings of this in vitro study, the choice of post material with a low or high modulus of elasticity did not prevent catastrophic failures in endodontically treated teeth without a ferrule.
Continue reading

The Massachusetts Dental Society Shares Flu Season Tips: Prevent the Spread of the Flu and Keep Your Mouth Healthy, Too


SOUTHBOROUGH, Mass..—Nov. 20, 2019—The U.S. Centers for Disease Control and Prevention (CDC) reported on a call with doctors this week that the United States is seeing more cases of the flu than is typical for this time of year, with 30 states already seeing flu activity—including Massachusetts. According to experts, when influenza is off to an early start, it can sometimes mean a more severe flu season.

While the CDC recommends a yearly flu vaccine as the first and most crucial step in protecting against influenza and its potentially serious complications, it’s also important to take everyday preventive actions to stop the spread of germs.
“By following some basic precautions, you and your family can stay physically healthy this season, while also maintaining good oral health,” said Massachusetts Dental Society (MDS) President Janis Moriarty, DMD.
Washing your hands frequently during any time of the year is important. But the MDS recommends that you also practice good hand hygiene when it comes to brushing and flossing your teeth.
“Germs on your hands can easily be transmitted to your toothbrush and then to your mouth,” Dr. Moriarty said. “It’s important to wash your hands before and after brushing your teeth and flossing. Most people don’t realize that viruses and bacteria can live on your toothbrush.”
According to the CDC, the flu virus can live on moist surfaces for 72 hours.
“Since toothbrushes are breeding grounds for bacteria, they should be kept isolated from other brushes, as well as surfaces that touch other brushes, like toothbrush holders and bathroom cups,” Dr. Moriarty added. “And, of course, you should never share your toothbrush, but this is especially true when you are sick.”
The chances of re-infecting yourself after an illness are low, unless your immune system is severely compromised.
“You should be replacing your toothbrush about every three months,” Dr. Moriarty said. “But, if you have any doubts, you may want to consider tossing your brush and getting a new one after you’ve been sick.”
If you do get sick this cold and flu season, the MDS encourages three simple ways to care for your mouth:

1)    Avoid cough drops with sugar or ingredients such as fructose or corn syrup. Sugar helps fuel cavity-causing bacteria, so sucking on sugar-filled cough drops can be as bad as sucking on candy.
2)    Drink plenty of water. When it comes to staying hydrated, water is best. It will help keep your saliva flowing and prevent dry mouth. Sports drinks may be helpful for replenishing electrolytes, but moderation is key since many contain high quantities of sugar.
3)    If you have a stomach flu that leads to vomiting, consider waiting to brush your teeth. Brushing right away can rub stomach acids all over your teeth’s enamel. Instead, swish with water or mouth rinse and spit, then brush about 30 minutes later.

For more oral health tips, visit massdental.org/oral-health. View this press release online at massdental.org/flu.
###
The Massachusetts Dental Society (MDS), a professional association representing 5,000+ member dentists and a statewide constituent of the American Dental Association, is dedicated to the professional development of its member dentists through initiatives in education, advocacy, the promotion of the highest professional standards, and championing oral health in the Commonwealth. For more information, visit massdental.org and follow the MDS on Twitter @MassDental.

Continue reading

Yankee Dental Congress® Will Contribute Millions to Boston Economy This Winter


SOUTHBOROUGH, Mass.—November 13, 2019—Yankee Dental Congress® 2020 (Yankee) will bring millions of dollars to the Boston economy this winter when it is held January 30 – February 1, 2020, at the Boston Convention & Exhibition Center. More than 26,000 dental health professionals and guests from around the United States are expected to attend this year’s event.
Yankee, which is New England’s largest dental meeting, is presented by the Massachusetts Dental Society (MDS) in cooperation with the dental societies of Connecticut, Maine, New Hampshire, Rhode Island, and Vermont.
“We are very proud that the Yankee Dental Congress is a major contributor to the Boston economy year after year,” said MDS President Dr. Janis Moriarty. “We strive to create an exceptional learning and networking experience for dental professionals, so they are excited to attend every winter.”
For the last 45 years, Yankee has welcomed to Boston thousands of dental health professionals to participate in the three-day conference, which features hundreds of continuing education (CE) courses and more than 400 exhibitors showcasing the latest dental products and technologies.
According to the Greater Boston Convention and Visitors Bureau, the 2019 Yankee Dental Congress® provided more than $11 million in economic impacts, including:
  • More than $2.87 million in attendee lodging and transportation
  • More than $2.13 million in attendee food and beverage spending
  • At least 3,500 total jobs supported
  • $65,000 in local taxes paid
  • More than $1.86 million in business services
  • Nearly $575,000 in attendee retail and recreation spending
Yankee Dental Congress® 2020 will continue to provide dental professionals with industry-leading speakers and more than 300 innovative CE opportunities to energize their passions and fuel advances in the dental field. Educational highlights will include courses on treating patients with special needs, dental sleep medicine, digital dentistry, HPV, geriatric dentistry, and an interprofessional symposium focusing on practice models that blend oral and systemic health. There also will be a special track of courses for new dentists designed to help them learn from experienced practitioners and network with their peers.
Yankee also will continue to provide complimentary registration and educational courses to public health dental professionals to help support those who provide vital oral health care to underserved and disadvantaged populations throughout New England.
For more information on Yankee Dental Congress® 2020, please visit yankeedental.com or call 877.515.9071.
###

Yankee Dental Congress® is New England’s largest meeting for professionals seeking the highest quality dental continuing education, as well as dental products, services, and resources. With more than 26,000 dental professionals in attendance from across the United States, Yankee Dental Congress® is the fifth largest dental meeting in the country. Held in Boston each January, Yankee is the best source in New England for industry professionals on the cutting-edge of oral health care. Yankee Dental Congress® is presented by the Massachusetts Dental Society in cooperation with the dental associations of Connecticut, Maine, New Hampshire, Rhode Island, and Vermont. For more information, please visit yankeedental.com or call 877.515.9071. 

Continue reading

Fracture rate of 188695 lithium disilicate and zirconia ceramic restorations after up to 7.5 years of clinical service: A dental laboratory survey

The Journal of Prosthetic Dentistry

Available online 5 November 2019

The Journal of Prosthetic Dentistry

Abstract

Statement of problem

The use of ceramic materials has increased significantly because of high esthetic demands, low costs, and ease of fabrication. Long-term, clinically based evidence is scarce, and laboratory studies have limited relevance in determining clinical durability.

Purpose

The purpose of this dental laboratory survey was to evaluate the fracture rate of layered and monolithic lithium disilicate and zirconia single crowns and fixed partial dentures after up to 7.5 years of clinical service.

Material and methods

Two commercial dental laboratories with a database system that was able to track the number of remakes because of fracture only were identified. Lithium disilicate restorations (monolithic and layered) were categorized according to restoration type (single crown, fixed partial denture, veneer, and onlay). Zirconia restorations (monolithic and layered) were categorized according to type (single crown, fixed partial denture) and then into anterior or posterior restoration. Restoration remakes due to poor fit, shade, or marginal integrity were excluded from the evaluation. Data were analyzed, and statistical significance was evaluated with chi-square tests (α=.05).

Results

A total of 188 695 (51 751 lithium disilicate and 136 944 zirconia) restorations were included in the analysis, with an overall fracture rate of 1.35%. Lithium disilicate monolithic single crowns had a fracture rate of 0.96%, which was significantly lower than that of layered single crowns at 1.26% (P<.05). When the different types of lithium disilicate restorations were compared, fixed partial denture (monolithic and layered) fracture rates were significantly higher than those of single crowns (P<.001). Monolithic zirconia single crowns (0.54%) fractured at a lower rate than layered zirconia single crowns (2.83%) and monolithic fixed partial dentures (1.83%) (P<.001), while layered single crowns (2.83%) had a higher fracture rate than that of layered fixed partial dentures (1.93%) (P<.001). Monolithic anterior and posterior zirconia restorations fractured at a lower rate than layered anterior and posterior zirconia restorations (P<.05). Posterior monolithic zirconia restorations fractured at a lower rate than anterior restorations, while posterior layered zirconia restorations fractured at a higher rate than anterior zirconia restorations (P<.05).

Conclusions

Within the 7.5-year period, restorations fabricated with lithium disilicate and zirconia restorations had relatively low fracture rates. Monolithic restorations fractured at a lower rate than layered restorations.
Continue reading

Stainability of acrylic resin materials used in CAD-CAM and conventional complete dentures

The Journal of Prosthetic Dentistry

Available online 5 November 2019

The Journal of Prosthetic Dentistry

Abstract

Statement of problem

The effect of staining beverages on the color of dentures made with computer-aided design and computer-aided manufacturing (CAD-CAM) is unknown.

Purpose

The purpose of this in vitro study was to evaluate the stainability of acrylic resins used in CAD-CAM–fabricated complete dentures compared with conventional materials.

Material and methods

Acrylic resin denture teeth from 3 different manufacturers (2 conventional and 1 milled) were obtained (N=45). Denture base acrylic resin specimens were made with 3 different techniques (compression molding, injection molding, and milling) (N=45). Conventional and/or milled acrylic resins were used to make specimens comprising both denture teeth and denture base acrylic resins (4 conventional, 2 milled denture bases with bonded teeth, and 1 all-milled) (N=105). All specimens were then immersed in coffee, red wine, or distilled water as control. The CIELab color differences between before and after immersion were determined by using a VITA Easyshade spectrophotometer. The tooth-denture base interface of the denture blocks was evaluated visually for the presence of stain. The CIELab data were analyzed by using ANOVA, and chi-square test was used for visual assessment (α=.05).

Results

Significant interactions were found between each acrylic resin material and each staining solution immersion when compared with distilled water immersion (P<.001). Denture teeth had similar color change after immersion in coffee (P=.149), while the most pronounced color change was observed with Portrait teeth upon immersion in wine (P<.001). Injection-molded denture base specimens exhibited less color change upon staining in wine than compression-molded or milled specimens (P<.001). Upon staining in coffee, milled specimens were not significantly different from injection- (P=.053) and compression-molded specimens (P=.180). The chi-square test showed a significant association between processing technique and stain accumulation at the tooth-denture base interface when evaluated visually (P<.001). Stain accumulation was greatest with compression-molded specimens (58%), followed by injection-molded (43%) and milled specimens with bonded teeth (8%). Monolithic teeth with milled denture base had no stain deposits at the tooth-denture base interface.

Conclusions

The stainability of milled acrylic resins was no better than that of conventional materials. However, CAD-CAM milled denture blocks with teeth and base acrylic resins had greater resistance to stain accumulation at the tooth-denture base interface than those of conventional processing methods.
Continue reading

Impact of caffeine on metabolic activity and biofilm formation of Candida albicans on acrylic denture resin in the presence of nicotine

The Journal of Prosthetic Dentistry

Available online 6 November 2019

The Journal of Prosthetic Dentistry

Abstract

Statement of problem

Candida albicans has been implicated in denture stomatitis, and this effect is exacerbated by nicotine exposure. However, studies have also suggested that caffeine exposure inhibits the growth of C. albicans. The interaction effects of nicotine and caffeine are not yet clear on the growth of C. albicans.

Purpose

The purpose of this in vitro study was to determine the effect of caffeine on metabolic activity and biofilm formation of C. albicans growing on acrylic denture resin while simultaneously exposed to nicotine and, if an effect were to be identified, whether this effect would vary depending on the caffeine concentration.

Material and methods

A total of 240 acrylic resin specimens were divided into 2 equal groups (120 each). Specimens in one group were processed to measure C. albicans metabolic activity, and those in the other group were processed to measure C. albicans biofilm attachment. Ten subgroups (n=12) were established within each group with different concentration combinations of nicotine and caffeine to test the interaction effect. The first subgroup was designed as a negative control, containing 0 mg/mL of nicotine and caffeine. The following subgroups all contained 8.00 mg/mL of nicotine, and the caffeine concentrations were prepared at the following 9 levels: 0, 0.25, 0.50, 1.00, 2.00, 4.00, 8.00, 16.00, and 32.00 mg/mL. Metabolic activity was measured by using a 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-carboxanilide (XTT) assay. Biofilm attachment was measured by using spiral plating and calculated in terms of the number of colony-forming units (CFUs)/mL. Descriptive statistics and a 2-way ANOVA were conducted to determine whether the concentrations of nicotine and caffeine used affected the biofilm attachment and metabolic activity of C. albicans (α=.05).

Results

The presence of 8 mg/mL of nicotine increased the metabolic activity and biofilm formation of C. albicans. When compared with the 0 mg/mL of caffeine and 8.00 mg/mL of nicotine group, caffeine from 1.00 to 4.00 mg/mL significantly increased C. albicans biofilm metabolic activity. Caffeine at 16.00 and 32.00 mg/mL significantly decreased C. albicans biofilm metabolic activity in the presence of 8 mg/mL of nicotine. Caffeine from 1.00 to 32.00 mg/mL significantly decreased the biofilm formation of C. albicans in the presence of 8 mg/mL of nicotine.

Conclusions

The presence of 8 mg/mL of nicotine alone increased the metabolic activity and biofilm formation of C. albicans. In the presence of 8 mg/mL of nicotine with different caffeine concentrations, the results suggest that, overall, caffeine at higher concentrations (16 and 32 mg/mL) inhibited the metabolic activity and biofilm formation of C. albicans on acrylic denture resin most.
Continue reading