Grinding It Out: The Best Material for Bruxers

Grinding It Out: The Best Material for Bruxers. Image: © RFBSIP - stock.adobe.com

You delivered beautiful dentistry to your patient, but now it’s gone. What happened to it? Bruxism.

Now what?

Here are what materials our research says you should use for patients who will grind their teeth all over your beautiful work.

Bruxism can happen during sleeping and waking hours. However, some research suggests that daytime bruxism is easier to manage because the patient knows they are doing it. Bruxism that happens while sleeping might be harder to identify and manage because many people don’t realize they grind their teeth while they sleep.¹

The Cleveland Clinic asserts that bruxism is a common sleep disorder, affecting approximately 10% of adults and 15% of children.¹ However, the International Journal of Environmental Research and Public Health estimates it to be as high as 30%.² The Sleep Foundation suggests slightly lower numbers for the adult population at 8% but a 50% rate for children.³

Whatever the incidence rate of bruxism, it’s reasonable to assume some of these people sit in your dental chair. Research published in 2022 in the British Dental Journal suggests the following when you identify patients who grind their teeth and have damaged their dentition⁴:

1. Practicality is of the essence in treatment planning and the complexities of damaged tissue reconstruction.
2. Dentists can choose a conformative or reconstructive approach depending on the patient’s grinding style. In other words, the reconstruction should work with the patients’ patterns, not against them.
3. Tissue preservation is paramount, so directly placed bonded composite materials are an excellent option. The materials are biocompatible, easy to fix, and inexpensive, and they absorb the stress of the patient’s bruxism.

The failure rate is high when the restoration is a complex fixed prosthetic or an implant-supported bridge. Use occlusal splints in these cases. Furthermore, reconstructive options with retrievability and removable features are the most effective prosthetics.⁴

Like any restorative case involving a crown, choosing the right materials for the job is essential to facilitate the best possible outcome. But which is best is a matter of perspective, the bruxism’s severity, the restoration’s location, and the patient’s preference.

For example, clinicians usually restore lost enamel in the anterior, adding material to fix short and flattened teeth. In contrast, posterior repairs usually fix chips, breaks, and fractures.⁵ Additionally, the esthetic concerns in each area of the mouth differ, which can also affect what you choose.

Returning to the Gold Standard

One suitable option for materials is gold, particularly in the posterior. The most robust material for a crown, gold can be an excellent choice for patients who grind their teeth. It withstands the force of bruxism even better than other materials and is less prone to breaking. It wears similarly to enamel and is easy on the opposing.⁵

Speaker and educator Jeffrey Lineberry, DDS, AAACD, owner of the Carolina Center for Comprehensive Dentistry in Mooresville, North Carolina, says that if the patient is willing to, he suggests gold when bruxism is an issue.

However, gold isn’t immune to the effects of bruxism; patients can destroy that too. Dr Lineberry says that while zirconia, porcelain, and lithium disilicate restorations break, patients usually wear a hole through the gold restoration.

That said, Dr Lineberry says that many patients do not like the idea of gold. Therefore, in cases where gold is the best option for their restorative case, clinicians should explain the benefit of it.

“My simple way of saying it to patients is, ‘Well, I can tell that you don’t enjoy coming to the dentist frequently. If I could put material in there that is not going to fracture and will be the longest-lasting material, would you be interested in doing that?’” Dr Lineberry says. “That’s different than saying ‘I want to put gold in your teeth.’”

Part of the problem is that when some people hear gold, they think it will be too expensive. Dr Lineberry says that when you present it to patients as an investment in staying out of the chair as often, it can help them overcome their anxiety about cost.

However, he also says that before you launch into a new treatment plan, it is essential to consider why the restoration broke or wore down in the first place. Is it a premature contact? Is the damage to the cuspal because of wearing down the front teeth, and now the back teeth are dragging? If you fix the problem but not the cause, you aren’t fixing anything.

“It is essential to look at the big picture,” he says.

What Else Might Work?

However, the best presentation might not overcome the patient’s objection to gold. Another great option when it comes to materials to choose from is zirconia. DDS Lab suggests that zirconia crowns, particularly those made of solid zirconia, are the best option for posterior crowns and bridges.⁶ A 2019 study in Materials also suggests that monolithic zirconia crowns with 1.0-mm thickness had high fracture resistance and low-stress values when subjected to 800 N of loading.⁷

There are a few reasons zirconia works. First, its strength and monolithic nature mean solid zirconia is an excellent choice for patients with clenching or grinding problems. Also, zirconia requires less tooth preparation, so clinicians do not have to remove as much tissue.⁶

In a continuing education course, experts at Dentalcare.com agree that solid zirconia is an excellent option for restoring teeth in the posterior for patients with bruxism because of its substantial strength and the material’s natural translucency. Also, it causes minimal wear on the opposing. However, they suggest layered zirconia for the anterior over the monolithic type because it is still strong but has improved esthetics due to its increased translucency and opalescence.⁵

Another option in the anterior is porcelain fused to metal. It is another esthetic material that is durable and long-lasting. However, it can cause more wear on opposing teeth than zirconia.⁵

Dr Lineberry also likes bonded lithium disilicate in these cases and sometimes monolithic zirconia for single units on back molars. He reaches for these materials when he has a good idea of what the patient is doing with their bruxism and can explain to patients what can happen if they grind on it. Setting proper expectations is critical, Dr Lineberry says.

“I tell patients if they can destroy what Mother Nature put there, they can destroy whatever is man-made,” Dr Lineberry says. “Bottom line, when you have a patient who can clench and grind hard enough to where they fracture a virgin tooth down the middle, that takes an immense amount of force to do that.”

Moreover, Dr Lineberry says it’s not a one-time issue but a cyclical force. If a person is biting and squeezing a thousand times a day or more, that’s a lot different from a person who chews only on a restoration.

“The other critical thing regarding indirect restorations is ensuring you have adequate retention and resistance, but also clearance,” Dr Lineberry says. “The material will not perform ideally if it’s too thin. You want to ensure all those things are right because when we see these numbers on how strong certain porcelain or zirconia is, it’s based on specific parameters. If you have less than that parameter, you will get less than that performance.”

Implants and Bruxism, a Terrible Mix

Complications with dental implants are often related to bruxers. Per a 2018 study published in Contemporary Clinical Dentistry, the “excessive occlusal overload” that bruxism results in is the leading cause of implant failure. These failures include implant fracture, screw loosening, screw fracturing, and porcelain fracture.⁸

The 2018 study titled “Assessment of Survival Rate of Dental Implants in Patients With Bruxism: A 5-Year Retrospective Study” found that out of 640 implants, a total of 275 had complications, including 145 screw-type and 130 cemented-type implants. There were 45 complications in single crowns, 125 in partials, and 105 complete prostheses. The failure rate was nearly 42.9%. Between the sexes, the survival rates were relatively similar on a year-by-year comparison and had a 70% rate of survival after 5 years.⁸

Like the British Dental Journal, a 2012 study from the International Journal of Biomaterials suggests that night guards are essential to protect the prostheses in these cases. Also, night guards for the maxillary teeth can help clinicians see what’s happening in the occlusal scheme when patients grind their teeth at night. This information can help design the implant case to prevent overloading on the implant in the bone from lateral stresses. Moreover, an acrylic resin night guard can prevent these stresses by distributing the force differently in the mouth.⁹

For example, if the appliance keeps the occlusal contacts in centric occlusion, it can prevent fractures. Also, the colored acrylic resin can show the wear inflicted by bruxism. If it is not worn through, the researchers suggest, the patient’s teeth grinding isn’t generating excessive force on the prosthesis.⁹

The design of the night guard protects the implants, too. By hollowing out the night guard at the implant sites in the mandible, no force is transmitted to the prosthesis. By relieving the occluding surface of the night guard for implant sites in the mandible, the occlusal force from bruxing isn’t transferred to the implants. Additionally, putting soft material around the crowns relieves the stress and decreases the impact of teeth grinding on the crown.⁹

In addition to using a night guard, the Foundation for Oral Rehabilitation recommends finding another way to treat the case that doesn’t involve implants or attempting to address the reasons behind bruxism before placing implants. It also makes suggestions for treatment considerations as follows¹⁰:

• adapting the implant type and diameter;
• determining the distribution and number of implants needed to adjust to the specific biomechanical and clinical requirements of the individual case;
• choosing a solid connection, particularly internal or conical; and
• changing and reinforcing the prosthetic’s superstructure or design to withstand bruxism force, like splinting through bars, using a removable-only restoration, using flat occlusion, using shortened or no extensions, and being careful with full-ceramic construction.

Dr Lineberry agrees that implants and bruxism have problems. He thinks paying particular attention to occlusion is essential in these cases. Implant occlusion differs from standard occlusion because the implants don’t have the periodontal ligament present, so the teeth compress, and the implants don’t. So, getting that implant-adjusted occlusion right is essential. Also, he designs stress breakers in the restoration.

“Some people may want to make them as strong as possible, but if something is going to fail, I would much rather it be the restoration and not the implant,” Dr Lineberry says. “The implant is more challenging to replace than [to] put another crown on it or to recement.”

So, What Implant Materials Hold Up Best to Bruxism?

The 2012 information on selecting the material for dental implants that can withstand the forces of bruxism was not definitive. Instead, the researchers say that clinicians at the time preferred metal to porcelain to protect the implants, especially for second molars in the maxilla. However, more research was needed at the time to support this preference.⁹

Ten years later, the research is still unclear about what materials to use for implants subjected to bruxism. The British Dental Journal suggests a few materials that might help diminish the effects of bruxism on the prosthesis. However, it also says successful management has a “poor evidence base.” Moreover, clinicians can try to reconstruct severely damaged dentition, but there are several caveats about how and each requires a lot of maintenance.⁴

References

1. Bruxism (teeth grinding). Cleveland Clinic. Updated May 7, 2021. Accessed August 3, 2023. my.clevelandclinic.org/health/diseases/10955-teeth-grinding-bruxism
2. Osses-Anguita ÁE, Sánchez-Sánchez T, Soto-Goñi XA, et al. Awake and sleep bruxism prevalence and their associated psychological factors in first-year university students: a pre-mid-post COVID-19 pandemic comparison. Int J Environ Res Public Health. 2023;20(3):2452. doi:10.3390/ijerph20032452
3. Suni E, Truong K. Bruxism: teeth grinding at night. SleepFoundation.org. Updated August 8, 2023. Accessed August 31, 2023. https://www.sleepfoundation.org/bruxism
4. Thayer MLT, Ali R. The dental demolition derby: bruxism and its impact - part 3: repair and reconstruction. Br Dent J. 2022;232(11):775–782. doi:10.1038/s41415-022-4293-8
5. James L. Bruxism: the grind of the matter, restorations. Dentalcare.com. Updated February 10, 2023. Accessed July 28, 2023. https://www.dentalcare.com/en-us/ce-courses/ce485/restorations
6. Abreu, M. PFM vs zirconia: which material is better? DDS Lab. April 23, 2018. Accessed July 27, 2023. https://blog.ddslab.com/pfm-vs-zirconia-which-material-is-better
7. Lan TH, Pan CY, Liu PH, Chou MMC. Fracture resistance of monolithic zirconia crowns in implant prostheses in patients with bruxism. Materials (Basel). 2019;12(10):1623. doi:10.3390/ma12101623
8. Chitumalla R, Halini Kumari KV, Mohapatra A, Parihar AS, Anand KS, Katragadda P. Assessment of survival rate of dental implants in patients with bruxism: a 5-year retrospective study. Contemp Clin Dent. 2018;9(Suppl 2):S278-S282. doi:10.4103/ccd.ccd_258_18
9. Komiyama O, Lobbezoo F, De Laat A, et al. Clinical management of implant prostheses in patients with bruxism. Int J Biomater. 2012;2012:369063. doi:10.1155/2012/369063
10. Parafunction. Foundation for Oral Rehabilitation. Accessed August 1, 2023. https://www.for.org/en/treat/treatment-guidelines/edentulous/patient-assessment/risk-assessment-special-high-risk-categories/parafunction