The effects of surgically assisted RPE are mostly dentoalveolar?
There is currently a trend to carry out more maxillary expansion with the overall goals to avoid extractions and improve breathing. This post is about the dental and skeletal effects of surgically assisted RPE.
Several speakers on the circuit and social media are suggesting that maxillary expansion is the answer to many orthodontic problems. One technique that is popular is surgically assisted RPE or SARPE. This is done when the sutures are closed in adult patients. Clinical experience informs us that if we need less than 5mm expansion a non-surgical approach may work, but if the amount of expansion is greater than 5mm we need to use a surgical approach. Nevertheless, SARPE carries surgical risk and we need to be cautious when we adopt this approach. As a result, I thought that this review of the effects of SARPE was very useful.
A team from Bologna, Italy did this study. The EJO published the paper.
Skeletal and dental effects of surgically assisted rapid palatal expansion: a systematic review of randomized controlled trials.
Francesco Bortolotti et al. EJO advanced access
What did they ask?
They asked this question:
“What are the immediate skeletal and dental changes from Surgilly Assisteed RPE in adult patients”?
What did they do?
They did a systematic review. The PICO was
Participants: Adult orthodontic patients (greater than 18 years old).
Comparator: Expansion appliances
Outcomes: Measurements from dental casts, radiographs and CBCT images.
They confined the search to randomised controlled trials. They did a standard systematic review by carrying out an electronic search, identification of possible papers, screening by two examiners. Risk of bias was done by the Cochrane Risk of Bias tool and the overall quality of evidence was assessed with the GRADE approach.
They intended to do a meta-analysis of the relevant data.
What did they find?
They identified 9 trials. The surgery consisted of a subtotal LeFort 1 osteotomy with or without pterygomaxillary disjunction. In all of the studies, the patients were asked to start expansion 7 days after the surgery.
One study was at low risk of bias, seven had some concerns, and one study was at high risk of bias.
When they looked at the studies. They excluded two studies because they did not report starting values, and another study was excluded because it only reported on palatal volume. This left five studies to be included in the quantitative analysis.
When they reported these measurements, they concentrated on dental and skeletal expansion. They felt that SARPE was an effective technique. When they looked at the contribution of skeletal and dental changes. This revealed that there was 3.3mm (95% CI= 2.8-3.9) skeletal change and 7.0mm (95%CI= 6.1-7.8) dental expansion.
The GRADE assessment suggested that the evidence ranged from moderate to low quality.
Their overall conclusion was:
“SARPE results in expansion that is mainly due to dental movements at the molars. While the skeletal effects maybe statistically significant, they are not clinically relevant”.
What did I think?
This review reported controversial findings. As a result, I have looked at this carefully. I thought that the authors carried out and reported the review well. They indeed followed the standard methodology. However, I was not clear on the individual measurements from the studies that they included in the meta-analysis. They simply reported these as dental and skeletal effects. This made me a little uncertain of their findings.
We also need to consider the strength of evidence, and this was low to moderate. Unfortunately, this is similar to many other systematic reviews. Consequently, this may be the best evidence that we have. It is undoubtedly higher than conference presentations and the multitude of social media posts that we see on the miracles of expansion.
I also wondered whether these findings were logical and I feel that they were. While the surgery may “free up” the maxillary complex for potential skeletal expansion, the expansion appliance is still tooth-borne. As a result, there is bound to be some tooth movement. However, I was surprised at the amount they reported.
Nevertheless, their findings were interesting. I was also interested to see that they stated in their discussion that as surgery does carry a risk, perhaps we should be considering non-surgically assisted rapid maxillary expansion in adults.
I wonder if there is a role for bone-anchored expansion? This is where we need further studies on this technique, which may be showing some promise.
Emeritus Professor of Orthodontics, University of Manchester, UK.
Have your say!
Interesting study. Is the expansion provided by SARPE worth the risk? Is it worth the cost?
What is so bad about a posterior crossbite? The the teeth still occlude and mastication can be acceptable.
Why not just accept a little dental expansion to improve posterior contact and live with the posterior crossbite?
In many adult patients I am happy to leave a bilateral crossbite ( with no deviation). As long as the aesthetics are acceptable whatis the point risking SARPE? I am very dubious ofnthe longterm benefits regarding airways etc.
If you have no posterior interference then posterior crossbite does not matter except for esthetic ie narrow smile
Why wait for seven days to commence activation after surgery? The callus would be consolidating.
This kind of puts a new spin on the concept of “expansion” in adults (with out any type of surgery). Remember several years ago the “point-counter point” article where one person argued for “slow expansion” in adults as a viable treatment modality? These conclusions makes that kind of argument look pretty silly. If SARPE provides a 2-1 raito of expansion to dental alvelor tipping, then with out SARPE I think we can conclude that there is probably no “expansion” in adults. I think that we need to consider not using the word “expansion” in patients older that 13 since I suspect that dental alvelor tipping is responsible for most of the change we observe clinically, even at that age.
What can we conclude about expansion in children and adolescents? Mostly dental? No long-term “airway” benefit?
If there is skeletal relapse, then it may not be a good idea to hold the teeth rigidly in the expanded position.
What type of appliances were used for the expansion? Were there bands on the teeth or were the expanders skeletally anchored with no bands. Which are well below the center of resistance of the maxilla? Research now shows that when bands are used that 70% of the expansion is dental tipping. When skeletal anchorage is utilized 70% is skeletal expansion.
Dr. O’Brian, any mention of differences in expansion performance when using banded vs bonded acrylic expanders? From my experience there is far more crown tipping with banded expanders. Disclusion of teeth permits mandibular shift changes and prevents inadvertent lower expansion by uncoupling the occlusion.
This is a very interesting discussion. The surgery is “done when the sutures are closed in adult patients”. However, our medical colleagues will point out that the (craniofacial) sutures provide a niche for (mesenchymal) stem cells. Lateral palatal expansion is a form of reductionism. By focusing one or two parameters, the full effects of the phenomenon, such as pneumatization, might be missed. The crowns of the teeth are “dumb” in the sense that they will take up whatever (functional) space is left. Other studies indicate that the “periodontal ligament” is not a ligament at all. It also appears to be a niche for (mesenchymal) stem cells. If the techniques deployed override the biologic pathways for homeostasis, then the outcomes might be less than favorable and not worth the time, effort, expense and pain.
I think we should lay to rest the stem cell angle. In humans, stem cells exist in multiple organs, and under culture conditions, any bit of scrap tissue can be coaxed by growth factor (FGF, EGF) to exhibit stem cell properties (proliferation, differentiation, self-renewal). If transplanted (in rodent studies), some of the stem cell descendants (donor) can integrate and participate in tissue repair of the host tissue but with unknown physiological outcomes. These studies have contributed to the enthusiasm and hyperbole in the stem cell field over the last 20 years. In reality, the field has now come to the sad conclusion that in humans, most stem cells in organs are dormant and non-physiological (except for the gastro-intestinal tract and blood where they are involved in daily renewal). Stem cells in bone sutures are likely to be vestigial remnants of our evolutionary past and there is no evidence that in the adult human, they can contribute significantly to bone turnover or development. After all that is said and done, the IPS (induced pluripotent stem cells) field (which is the most mature and produce stem cells out of a single cell) has not produced a shred of utility and the most advanced trials at present are for treating eye disease (macula degeneration). Things can change in the future but for now, invoking stem cells as some sort of virtual tissue response to expansion requires careful scientific study.
Dear Dr. O’Brien, thank you for the insightful summary.
From what I gather, the dental measurement at the intermolar distance also includes the skeletal effect of expansion, thus in the short term a total of 7mm expansion makes roughly half of it a skeletal effect which seems reasonable. That goes well in line with Chamberland and Proffit, 2011 on the short and long-term effects of SARME where they showed that as time goes by, the dental component relapses while the skeletal expansion remains stable, and by the end of the follow up nearly 80% of the remaining expansion was skeletal. Hence with some overcorrection it may seem plausible to obtain clinically satisfactory results.