Why dentists don't recommend Maryland Bridges?

[joey87]

TLDR: I have a tooth fracture on my maxillary central incisor (#21) after failed RCT and the dentist recommended an implant, but I have an extreme phobia and risk factors (smoking, SSRI, PPI). Both dentists I talked to do NOT recommend getting any RBBs, but studies show a different picture.

I'm a science nerd so I have read over 30 clinical studies and meta-analyses on PubMed, and it turns out that the success rate of RBBs/Maryland Bridge is not so bad, despite being slightly inferior to implants (over 95% for implants)

Studies reference on RBBs​

Key points:

• Higher success rate on maxillary anterior teeth, and when only 1 tooth is missing
• The most common complication is debonding in around 20% of cases, which is comparable to the 20% risk of developing peri-implantitis.
• Cantilever RBFDPs have a better survival rate for missing central maxillary incisors compared to other designs
• Counter-intuitively, the one-retainer design is better. The two-wing design is the most prone to failure compared to the cantilever design.
• In the past, the two-retainer design was the most commonly used, which is more prone to failure, so it could explain the negative perception by dentists. A lot of improvements have been made in recent years, with the optimization of cementation materials around 2013. That’s why the success rate is better in more recent studies.
• I have a deep bite and some sources are suggesting it could increase the debonding risk, but is also a risk for implants (I could not find any study on RBBs survival rate with deep-bite)
• Zirconia, Alumina, and Ceramic have great documented success rates, but many studies recommend going with Zircona framework material

2018 - Meta-analysis of 29 studies (2300 RBBs)
“Meta-analysis of these studies reporting on 2300 RBBs indicated an estimated survival of resin-bonded bridges of 91.4% after 5 years and 82.9% after 10 years. RBBs with zirconia framework and RBBs with one retainer tooth showed the highest survival rate. Moreover, the survival rate was higher for RBBs inserted in the anterior area of the oral cavity compared with posterior RBBs. The most frequent complications were de-bonding (loss of retention), which occurred in 15%”

2021 - Integrative review of 23 clinical publications on Anterior-Region RBBFDPs
“5-year survival rate at 86.2% for metal-framed prostheses, 87.9% for zirconia prostheses, 93.3% for alumina prostheses, 100% for glass or ceramic prostheses, and 81.7% for fiber-reinforced composite restorations. Failure rates did not significantly differ between the different material groups or between the single- and double-retainer groups.“

2007 - Meta-analysis of 17 studies
“Meta-analysis of these studies indicated an estimated survival of RBBs of 87.7% after 5 years. The most frequent complication was debonding (loss of retention), which occurred in 19.2% of RBBs over an observation period of 5 years. The annual debonding rate for RBBs placed on posterior teeth (5.03%) tended to be higher than that for anterior-placed RBBs (3.05%)”

2018 - Systematic review of studies from 1965 to 2017
"Success was defined as the RBFPDs remaining in situ and not having experienced debonding, biological failures, or mechanical failures at the examination visit. Meta analyses of the included studies showed an estimated 5-year success rate of 88.18% for the metal framework RBFPDs and 84.41% for the nonmetal framework RBFPDs. The estimated 5-year success rate for each nonmetal material category was 92.07% for zirconia, 94.26% for In-Ceram alumina, and 84.83% for fiber-reinforced composite. The failure rate was not statistically significant among the single, double, and multiple retainers RBFPDs. The 5-year clinical performance of RBFPDs is similar to the performance of conventional fixed partial dentures (FPDs) and implant-supported crowns."

2023 - Systematic Review of 11 articles after 8.2 years (687 patients, 783 RBFPDs)
"A total of 142 failures were reported for 783 prostheses, the most frequent being debonding" (success rate of 82% without debonding)
"Conclusion: RBFPDs are a viable clinical option for the rehabilitation of patients with single edentulous spaces, mainly when using a single retainer and a zirconia-ceramic prosthesis."

2013 - Meta-analysis of 49 studies on RBBs
"Estimated three-year survival rates were 82.8% for metal-framed, 88.5% for fibre-reinforced composite and 72.5% for all-ceramic resin-bonded bridges. (mean)"

2018 - Systematic Review of 8 studies
"The estimated 5-year survival rate of all-ceramic RBFDPs was 91.2%. Debonding and framework fracture were the two most frequent technical complications, and the estimated 5-year debonding rate and fracture rate were 12.2% and 4.8%, respectively. Additionally, cantilevered all-ceramic RBFDPs had a higher survival rate, lower debonding rate, and fracture rate compared with two-retainer all-ceramic RBFDPs. Zirconia ceramic RBFDPs had a lower incidence of failure but a higher debonding rate compared with glass-ceramic RBFDPs"


2017 - Clinical study on 87 RBFDPs in central incisors (108 zirconia RBFDPs / 75 maxillary incisors)
“Zirconia ceramic RBFDPs yielded a 10-year survival rate of 98.2% and a success rate of 92.0%” … “all-ceramic cantilever RBFDPs provide an excellent minimally invasive treatment alternative to implants and conventional prosthetic methods when single missing anterior teeth need to be replaced”

2018 - Study on 206 RBBs (anterior region)
“Overall survival rate of anterior region RBBs was 98% at 5 years, 97.2% at 10 years, and 95.1% from 12 years till 21 years”

2011- Study on 84 RBFPDs
“Overall survival rate has been computed as being 77% after 10 years of service, 88% after 10 years”

2004 - Study on 74 RBFPDs (64 in anterior region)
“A mean survival rate better than 69% after a 13-year observation period was calculated. Including the rebonded restorations, a mean functional survival rate of 83% was estimated. A total of 18 failures (24.3%) of all restorations were observed, the main cause being loss of retention.”

2018 - Meta-Analysis of 19 studies
“After evaluation of the selected articles, it is likely that cantilever design all-ceramic RBFDPs are more successful than two retainer design in the anterior region”

2018 - Review of 12 studies
"Conclusions: The use of cantilever RBFDPs showed promising results and high survival rates."

2014 - Study on 42 RBFDPs (cantilevered ceramic zircona in anterior region, single-retainer design)
“During a mean observation time of 61.8 months two debondings occurred. Both RBFDPs were rebonded using Panavia 21 TC and are still in function. The overall six-year failure-free rate according to Kaplan-Meier was 91.1%. If only debonding was defined as failure the survival rate increased to 95.2%.”

2022 - Follow-up clinical article on 3 patients over 26 years
"Conclusions: Cantilevered single-retainer all-ceramic RBFDPs today made from veneered zirconia ceramic can be considered a standard treatment for the replacement of incisors and provide an excellent esthetic outcome with a long-term preservation of soft tissues in the pontic area."

2011 - Study on 38 anterior RBFDPs
"The 10-year survival rate was 94.4% in the single-retainer group. "


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So what am I missing? I don't want to sound like a smart ass who pretends to know better than professionals, but the dentists I have talked to never did any RBBs so they don't have first-hand experience and I'm not sure they have read the recent studies. Obviously, my phobia makes me susceptible to confirmation bias, that's why I came here to have other opinions. I tried not to cherry-pick the studies and included some with less favorable outcomes, but I ignored older studies published more than 20 years ago after reading how much of a difference the recent technological improvements made.

 

[Gordon]

Used them for decades, have had great success with them and have recommended them on here multiple times.
So I have no clue why the dentists you went to didn't like them. What reasons did they give to tell you why you weren't a suitable case for one?

 

[joey87]

Thanks for the reply, this is encouraging. The reasons given were the high failure rate. Most professionals seem to hate them because patients come back complaining after it falls off. Some dentists even refuse to make them except for temporary situations with kids. That's the only reason why I'm so hesitant, and also if they're right and the bridge fails I will have bone loss after the extraction, and getting an implant will be even more complicated.

After many phone calls, I finally found a clinic doing Maryland Bridges but they seem to prefer the two-wing design and I'm not sure about that.

Do you have any opinion on cantilever design vs. two-wing? Some studies found the one-wing design has a lower debonding risk

resin bonded bridges have a much higher success rate and longevity when they are only bonded with one wing. When I first heard this it sounded counter-intuitive until you think about the physics. When you use only one wing the pontic can move with the abutment under load. With two wings, especially around a curve, the forces are directed differently and the movement of one tooth causes the bond to be flexed causing a bond failure over time.

Since using these criteria, and fabricating resin bonded bridges with only one wing I have come to appreciate their place int he appropriate clinical situations. In this case we placed e.max resin bonded bridges with wings on the central incisors.

Source: Dr. Lee Ann Brady

RBBs with one retainer had a significantly higher survival rate (P < 0.0001) and a lower de-bonding rate (P = 0.001) compared with RBBs retained by two or more retainers.

A systematic review of the survival and complication rates of resin-bonded fixed dental prostheses after a mean observation period of at least 5 years (meta-analysis of 29 studies)

Using only one retainer wing with a minimal preparation of the enamel is minimally invasive and provides long-term survival and success rates which exceeded those obtained with implant-retained crowns.8, 9, 23, 24 In these studies the clinical results with maxillary and mandibular RBFDPs did not differ significantly. A systematic review of the survival and complication rates of RBFDPs after a mean observation period of at least 5 years, confirmed the superior survival of cantilevered single-retainer all-ceramic RBFDPs.25 In addition, cantilevered metal-ceramic RBFDPs with a metal framework showed a better clinical outcome compared with conventional two-retainer RBFDPs.26, 27 It was suggested that shear peel forces, resulting from differential movements of the two abutment teeth in the conventional two-retainer RBFDP design, are reduced in the cantilevered single-retainer design.26

It is assumed that the cantilevered single-retainer design in all-ceramic RBFDPs also reduces tensile stresses developing in the bonding interphase when using a two-retainer design due to the differential tooth mobility of splinted abutments during functional loading. This might be especially important when lateral incisors are to be replaced because of the differential movements of the central incisor and the canine during protrusion and laterotrusion. In addition, the cantilevered pontic might act as leverage for functional loads resulting in an increased tactile sensitivity of the abutment tooth compared with the abutments in the two-retainer design.28 It can be hypothesized that the higher tactile sensitivity leads to patients perceiving possible unfavorable stresses at an early stage and then unconsciously avoiding them, which might be one reason for their better survival and success rates.

This seems to be true for most teeth, however, a study made some nuances about maxillary central incisors:

Splinting the two retainer wings on the adjacent central incisors has been shown not to create the problems seen with two-retainer RBFDPs splinting a central incisor and a canine because the splinted central incisors move in a similar direction during functional loading while canines moved in a different direction especially during laterotrusion.20 The canines had not been selected as abutment teeth in order to avoid inference of the retainer wings with the existing canine guidance in a deep bite situation where the incisors allowed insertion of the retainer wings due to the existing overjet.

Study source: Single-retainer all-ceramic resin-bonded fixed dental prostheses: Long-term outcomes in the esthetic zone

 

[Gordon]

After many phone calls, I finally found a clinic doing Maryland Bridges but they seem to prefer the two-wing design and I'm not sure about that.

Don't blame you! I wouldn't want one in my mouth...

Do you have any opinion on cantilever design vs. two-wing? Some studies found the one-wing design has a lower debonding risk

Yes, cantilever ALL the time. The worst thing that can happen with the 2 wing design is if one wing de-bonds, the tooth beneath the de-bonded wing will decay like crazy. Single wing will come right out.

Most professionals seem to hate them because patients come back complaining after it falls off. Some dentists even refuse to make them except for temporary situations with kids. That's the only reason why I'm so hesitant, and also if they're right and the bridge fails I will have bone loss after the extraction, and getting an implant will be even more complicated.

They don't fail very often if they're constructed properly and cemented properly. The lab work is a bit challenging and there needs to be some basic rules of design followed.

I've had one case with a Md bridge replacing a central incisor, the patient fell and hit his mouth, knocking out the remaining central incisor with the bridge still attached to it...

I had another case where one kept failing, turned out the patient (non-verbal autistic lad) didn't like it in his mouth and used the wire from his headphones to lever it out! Even under those conditions it resisted his efforts for several months at a time, before we figured out what the heck was happening and didn't put it back in!

 

[joey87]

Two more questions for you, please

Have you seen many cases of deep overbite with a Maryland bridge? This clinic says “Deep overbite would also contraindicate a Maryland Bridge” but pretty much every other source I found says there is often a workaround. My deep overbite never caused any problem, I don't think it puts more pressure on the incisors, and there seems to be enough place for the wings. Dentists never said anything about malocclusion, in fact, I didn't even realize I have a deep overbite until I read this stuff recently
I understand you can't give specific advice regarding my case without having seen it, I'm just wondering how often it's a dealbreaker for a bridge generally speaking. I'm scheduling an appointment this week with a clinic to check this out.

And last question, how often have you seen bone loss complications following extraction and replacement with a bridge? Things like adjacent teeth moving, gum recession, and stuff like that.

Thanks for everything you are doing with this forum, I really appreciate it! This is so helpful for persons suffering from phobia. Average people have no idea how stressful this can be. When I was told I'd need an implant I was literally at the point of not eating and not sleeping for a week, couldn't even work due to brain fog and constantly worrying...

 

[Gordon]

I'm just wondering how often it's a dealbreaker for a bridge generally speaking

It's not a big deal at all.

how often have you seen bone loss complications following extraction and replacement with a bridge? Things like adjacent teeth moving, gum recession, and stuff like that.

It's pretty common to see them, but they're usually due to other unrelated things, not just the extraction, if that makes sense?

How did you get on at the clinic?

 

[joey87]

Well, it only got more complicated since my last post...

A dentist looked at my deep bite occlusion and told me that I didn't have enough place for the wing of the bridge without drilling the palatal surface, so he recommended an orthodontic treatment to move #11 forward. But my local orthodontic clinic has a 2 years wait time and I don't know if a generalist can do it.

Today I talked to another dentist and told him about the deep bite occlusion and the idea of moving #11 forward, but he thinks it's a bad idea because I will need a fixed retainer, but there won't be enough place for it with the wing of the bridge, so he said my tooth would be at high risk of displacement.

Here are 2 videos of my occlusion:
https://drive.google.com/file/d/1YGQozfifwYbFY9G65FuyjsEaCUoau5Vo/view?usp=sharing
https://drive.google.com/file/d/1VZWVBVznaTAWciWg25FXQxeKK_3nFr6P/view
Xrays:
https://drive.google.com/drive/u/0/folders/1QbZJREzQuTjYSBDPLNMbtUZxcgU3Drl5

I did the test with a strip of aluminum foil between the 2 incisors. If I just close my mouth normally, I can pull the strip out (I can feel some resistance). If I close my mouth strongly and put pressure on the teeth, then the aluminum foil will not come out easily and sometimes tear into 2 pieces, but I have to apply constant pressure.

I'm a little bit depressed right now, I spent so much time researching this and talking to dentists, and I still don't know what to do or where to go.

 

[Gordon]

There are other ways round this if it's a problem. But I really can't advise without actually seeing your mouth, videos don't help, sorry.

 

[joey87]

Today marks 1 month since I was told I would need to get my central incisor pulled. Since then, I have seen 4 different dentists and spent almost $1000 and I am going NOWHERE Nobody can help me, they keep referring me to another clinic, who refers me to another again... I called every single clinic in the region.

Dentist #1 is the endodontist who diagnosed the longitudinal fracture and said he can't help me

Dentist #2 confirmed I have a deep bite and #11 doesn't have enough place for the wing. Recommended ortho but said he couldn't do it.

Dentist #3 said doing ortho is a bad idea and said I should put the wing of the bridge on #12 instead, but I think using a lateral incisor abutment is a bad idea. Re-confirmed #11 can't hold the wing, I need orthodontic treatment to bring it forward a little bit. But apparently, the ortho retention wire will make it very complicated to place the wing.

Dentist #4 agreed that bridging #21 with #11 is a better idea than the lateral incisor, but said that my case is too complex for him. Referred me to a prosthodontist to get an opinion on the bridge, and said I needed to see a real orthodontist.

There is only 1 orthodontic clinic where I live and they told me the wait time is 2 years before they can see me for the first time. I'm very anxious and depressed, I don't know what to do and I'm afraid there's no solution...

The 4 dentists strongly think that the 2-wings model is always better and looked at me like it made absolutely no sense to use only 1-wing, but I think they're wrong about this.

 

[Gordon]

Dentist #3 said doing ortho is a bad idea and said I should put the wing of the bridge on #12 instead, but I think using a lateral incisor abutment is a bad idea.

Not necessarily. Depends on the root of the lateral.

You're right that 2 wings is a bad idea. Other than that, I can't really help you.