our patient calls the office on Monday morning and tells your receptionist that her crown fell off her front tooth. You know the truth before she walks in the door – the post and core that was in the tooth, is still inside the crown that is inside the ziplock bag, that is inside your patient’s purse! Your dental team thinks that this is going to be a quick recement, but you’re already worried that there isn’t going to be enough tooth structure to even recement the post/core/crown temporarily! Sure enough, there is hardly any tooth structure above the gum line, and what is there, is decayed ;(. If you haven’t had an anterior crown that you placed on a patient fall off yet, it’s probably only a matter of time. Losing a front crown is one of the most sensitive issues for our patients…and when it is dentistry that we’ve placed, the patients can be particularly unhappy.
What do we know about treating anterior teeth with crowns?
Two prosthetic considerations will give us the highest chance for success with the definitive restorations. The first is ‘ferule.’ Ferule is the amount of tooth structure that the crown can grab. The ferule is the facial, palatal, and interproximal tooth structure that is available with our preparation. We all know that the more natural tooth structure that we have, the better off we are for long term cementation of our crowns. OK – here’s the important part - even with our wonderful adhesive dental cements, we must have 2 mm of tooth structure to bond our restorations. Less than 2 mm of tooth structure, the crown cementation will become less secure and stable.
The second consideration besides ferule, is the total tooth structure to secure our crown. Now adhesive dentistry has helped us significantly with this issue; however, we still need 4-5 mm of tooth structure, or tooth structure + build-up, to have ideal retention of our bonded crown. This then leads us to the discussion of post and cores for the endodontically treated tooth. When do we need to place a post on endodontically treated teeth.
Dentistry has changed in our understanding and approach to placing posts in endodontically treated teeth. Through research, we have come to understand that posts, especially if the canal system is over instrumented and the canal space is artificially enlarged to support a post, this can lead to fracture of the root down the road. In fact, many dentists have shied away from placing posts because of this concern, but the reality is that there are still indications for placing posts. In my practice, I place posts when I am concerned about the ability of the core build-up to maintain bonded to the tooth structure. Posts do not strengthen roots; posts help us secure, or anchor, the core build-up restoration to reduce the risk of build-up material separation from the tooth structure. But please remember - posts do not strengthen roots!
The technique for placing posts is not particularly complicated, but there are several important factors to consider.
First, we were taught in dental school that the post needs to extend down the root system leaving about 3 mm of apical gutta percha. This technique was related to the cements that we had available at the time, but now that we have the opportunity to chemically bond the posts, perhaps we can reduce the length of the post so that the terminal end of the post is in a thicker area of the root system. With the end of the post in thicker root structure, the risk of root fracture in the future is reduced.
The second issue to consider with the posts is the type of post that we use. There are several options currently for direct posts – metal posts, fiber posts, and fiber reinforced zirconia posts. I definitely do not want to use a metal post when restoring an anterior tooth. Even with our ability to opaque the post and core with our composites, we will need to use a more opaque crown material to block out the low value of the tooth that is common with metal posts. So, I absolutely know that it will be easier for my ceramist to create an esthetic crown if I use a tooth-colored post with a tooth-colored build-up material.
That leaves the choice between an all-fiber post or a zirconia/fiber post. How do you choose? Research suggests that stiff posts, bonded into the root, gives us the most stability in our direct post systems. The flexibility of the all-fiber posts can lead to future breakdown of the adhesive interface. So, given the choice, I am going to choose an esthetic, stiff post, like the DentaPost from Brassler.
The third and final critical issue to consider is how are you going to cement the post. The best, most predictable, and turns out the most simplified technique that I have found is to use my core build-up material as the post cement. My technique is as follows:
1. Create post space – I like to have about 5 mm of post into the root canal system. This would typically give me a 10 mm post – 5 mm into the canal system, 2 mm of tooth structure (ferule) and 3 mm extension of the post beyond the ferule
2. Etch the canal system and tooth structure with 37% phosphoric acid for 15 seconds, using a microbrush to lightly ‘scrub’ the etchant (alternatively, you can use a self-cure self etch adhesive system)
3. Rinse and make sure all phosphoric acid is removed
4. Remove excess water so that the dentin is left moist, but no pools of water
5. This is critical – you must use a self-cure adhesive – if you use a light cured adhesive, the effect of the light down into the canal system is going to be limited (I use Cosmedent Complete with the self-cure activator), air thin and use microbrushes to remove excess adhesive
6. Inject tooth colored core build-up material into canal system (I use Cosmecore A2 with the metal Centrix syringe tip), place post into the canal, and continue to use the Cosmecore build-up material around the post and onto the tooth structure.
7. Light cure for a full minute. Now your tooth is ready for the final preparation!
To get a fuller explanation of ferule and all issues related to placing the direct esthetic post and core, check out mycourse on dental online training. I hope that this review is helpful and I look forward to sharing more techniques with you down the road!
Yours for better dental health,
Dennis Hartlieb, DDS, AAACD
DOT Founder
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Materials Included
Typodont model
3D Printed ZRBB
Ribbond strip
Putty Matrix Material
Brasseler: Fine Modified Flat-End Diamond Bur, ET9 FG Needle Fine 8 Blade Red Carbide Bur, 7408 OS1 FG Football Carbide Bur, Fine Needle Mosquito Diamond Bur, Medium Depth Cutting Diamond Bur, Feather Lite Polishers,Polishing Cups
Cosmedent: Universal Composite Renamel NANO Plus (A1), Renamel Microhybrid MWO, Ranamel Microfill A1, Renamel Hybrid flowable A1, Light Incisal, A1 Opaquer, White Opaquer,
Light Brown tints, Enamelize, Unfilled Resin Flexidiscs, Flexibuffs 1/2", #1 artist’s brush, Silicone Polishing Points, IPC Off Angle Short Titanium Coated Composite Instrument
Materials Needed, not Included
Loupes
High Speed
Slow Speed
Curing Light
Alcohol Gauze
Boley Gauge
Floss
Teflon tape
Mylar strips
Meet Dr. Dennis Hartlieb
Dr. Dennis Hartlieb owns his own practice in Chicago,IL and has been teaching dentistry for over 30 years. Dr. Hartlieb is the CEO and the main instructor at Dental Online Training. He is an active member in the American Academy of Cosmetic Dentistry where he’s both an Accredited Member and Examiner for Accreditation.
Dr. Hartlieb is also the President of the Chicago Academy of Interdisciplinary Dentofacial Therapy, and a member of the prestigious American Academy of Restorative Dentistry.
Meet Dr. Angela Luek
Dr. Angela M. Lueck is a Wisconsin native and was the youngest female in her class from Marquette University in 1998. Since completing her residency she has consistently taken more than 100 hours a year of continuing education to keep current on the latest trends, techniques, and materials available in dentistry.
She volunteers her time to teach at Marquette University providing the students additional training with anterior and posterior bonding techniques as well as dental photography. She is also the co-chair of the mentorship program at the University. Dr. Lueck has been voted as one of Milwaukee’s top dentists multiple times by Milwaukee Magazine.
Meet Clare O'Neill
Clare O’Neill is the Director of Operations at Dental Online Training and has a professional background in digital marketing. Clare has certifications in content marketing and digital advertising. Clare has expertise in social media marketing, email marketing, content marketing, website management, and project management. Clare has been using Canva for over 5 years and is a self-proclaimed Canva Queen.
Clare graduated from Georgia State University with a Bachelor’s degree is Sociology. Clare wanted you to know that she is a dog person, loves the colors emerald green and periwinkle, and would eat french fries at every meal if she could!
Meet Dr. Jim Mckee
Dr. McKee is a member of the Spear Resident Faculty. He has maintained a private practice since 1984 in Downers Grove, Illinois where he treats a wide variety of cases with a focus on predictable restorative dentistry. He is a member of the American Academy of Restorative Dentistry and former president of the American Equilibration Society.
He has lectured both nationally and internationally for over 25 years and directs several study clubs. Dr. McKee graduated from the University of Notre Dame in 1980 and earned his dental degree from the University of Illinois College of Dentistry in 1984.
Meet Kirk Behrendt
Kirk Behrendt is a renowned consultant and speaker in the dental industry, known for his expertise in helping dentists create better practices and better lives. With over 25 years of experience in the field, Kirk has dedicated his professional life to optimizing the best systems and practices in dentistry.
Kirk Behrendt is the founder of ACT Dental, and his vision is driven by the commitment to provide highly personalized care to the dental profession. By creating a talented team of experts, Kirk and his team continue to positively impact the practice of dentistry on practice at a time. Kirk lectures all over the world to help individuals take control of their own lives.
Meet Dr. Melissa Seibert
Melissa Seibert is a comprehensive dentist proudly serving in the Air Force. She holds a dual faculty appointment at Uniformed Services University and Creighton Dental School. She serves on the editorial board for Inside Dentistry.
Her current research projects involve investigating ceramic overlays, zirconia and salivary contamination of universal adhesives. Dr. Seibert is the creator and host of the top dental podcast, Dental Digest. She lectures to national and international audiences.
Meet Olivia Wisden
Olivia Wisden is the founder & CEO of TwoLips Creative. What started as an events discovery app pivoted into a creative agency that specializes in working with startups, small businesses, and organizations who are looking for bold, impactful designs and strategies.
She has worked with dozens of brands over the years ranging from the City of Madison to product launches and beyond.
Meet Dr. Sofya Kats
Dr. Sofya Kats is local to Milwaukee, WI. She grew up in Bayside and attended Nicolet HS, UW-Milwaukee and Marquette University School of Dentistry. Dr. Kats is a member of the Greater Milwaukee Dental Association, Wisconsin Dental Association, American Dental Association, and The Forum Study Club (oldest Dental Study Club in the United States).
Dr. Kats loves the art of dentistry, and healing it can bring to her patients. She volunteers her time by going on international dental mission trips and local events, such as the Mission of Mercy (free dental care sponsored by the Wisconsin Dental Association).
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