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Management of Class III Malocclusion using Bone Anchors: True Orthopedics Part II – Clinical Technique
BY TUNG T. NGUYEN, DMD, MS
The following article outlines our protocol for early treatment of Class III malocclusion using Bone Anchored Maxillary Protraction (BAMP). In a future post, we will include more clinical tips and tricks, as well as information on how to handle unusual complications.
Age of the Patient
The typical age for BAMP treatment for a patient who has a Class III skeletal relationship with a component of maxillary retorgnathia is 11-14 years. Broadly stated, the younger the patient, the better the chance for orthopedic protraction of the maxilla and midface. The success of BAMP treatment is primarily dependent on 2 factors:
Surgical Management – Placement of the Plates
We recommend the Bollard plate with the Y-Design (center plate in the image below). The Standard (screw holes in-line) design can also be used with success.
The maxillary bone plates are inserted in the infrazygomatic crest, with the plate arm emerging through attached tissue near the maxillary molars. The mandibular bone plates are inserted between the mandibular lateral incisors and canines – again with the intraoral attachment emerging from attached tissue. For the placement of both the maxillary and mandibular plates, a small flap is raised with a design that maintains good blood flow to the tissue. We refer all plate placement to qualified oral and maxillofacial surgeons familiar with the technique and treatment goals.
Ideally 1.5-2.0 mm of cortical plate thickness is needed to ensure both short-term and long-term stability of the plates. For these reasons, we often delay BAMP treatment until the age of 11. In the mandible, extraction of primary canines (M & R) will expedite the eruption of the permanent canine to help provide the inter-radicular space needed for the plates and screws.
If the permanent mandibular canines have not yet erupted, the mandibular plates can still be placed, however. In these special circumstances, we use the maxillary plates with 3 screw holes (in-line, not the Y-Design) and utilize the bottom 2 screws with the most apical hole placed just beneath the lateral incisor root. The plates are placed with a distal angulation – so that the hooks on the plates still emerge into keratinized gingiva in the region just buccal and apical to where the permanent canine crown will erupt.
The screws can either be inserted with the surgeon making small pilot holes or using self-drilling screws. We recommend the use of a pilot hole, as it decreases the mechanical stress on the bone and facilitates faster healing.
The plates are loaded 3-4 weeks after surgery, if they are stable. We test stability clinically at each plate before loading.
Initial traction is 100g per side for 6 weeks. The patient is instructed to wear the elastics 24/7 and to change the elastics at every meal. Make sure that the patient does not experience sharp or dull nagging pain when wearing the elastics. If the patient experiences sharp pain upon elastic loading, instruct them to discontinue elastic wear immediately. Sharp pain usually indicates plate instability. Stopping traction is most often the best way to allow the plates to re-stabilize.
After 6 weeks of initial loading, the traction force can be increased to 150g per side for an additional 6 weeks. The final loading force is 250g per side about 6 weeks later.
Often, patients who have a Class III skeletal relationship with a deepbite and anterior crossbite require some sort of bite-opening appliance to allow the crossbite to be most efficiently corrected. To accomplish this goal, we place temporary bite turbos on the mandibular first molars, but a retainer with a posterior bite plate is also effective.
Most often, we start BAMP treatment with a full fixed appliance in the lower arch to decompensate the mandibular incisors. Our experience suggests that young patients are more motivated to wear elastics until the anterior crossbite is corrected. By simultaneously decompensating (proclining) the lower incisors with a fixed appliance, we know the true amount of orthopedic correction needed in order to obtain positive overjet with an aligned mandibular arch.
Once positive overjet is obtained, we place full maxillary appliances and continue elastics to overcorrect to ~4mm overjet or ½ cusp Class II. Elastics can then be decreased to only night time wear for retention of the orthopedic improvement until mandibular growth is completed. After debond, the patient is seen every 6 months for growth observation. If the overjet decreases, we increase elastic wear to full time in order to help account for continued Class III mandibular growth. In the rare instances in which the overjet increases, the patient can cut elastic wear to every other night. The plates and screws can often be maintained successfully for several years and then removed in conjunction with 3rd molar extractions, if indicated.
In summary, the clinical protocol is as follows:
BY TATE H. JACKSON AND CHING CHANG KO
Orthodontic information is everywhere: from traditional publications to open-access web-based outlets to Facebook and Instagram.
Increasingly, we are confronted with a question:
A recent publication in the European Journal of Orthodontics offers an interesting perspective and approach.
Livas and Delli used a Web screening tool, Altmetric, to conduct an analysis of the visibility of articles published in eleven Orthodontics Journals in the popular press (e.g. New York Times), social media such as Facebook, and on-line citation managers like Mendely. The authors monitored visibility two time points, January and April of 2017 and reported the top 200 articles referenced, as well as an AAS (Altmetric Attention Score – range 1-199) for each article. The full list of the top 200 articles is here.
AAS serves as a measure of digital attention. In other words, how visible was the journal article in our web-based world - in the popular press and social media? A score of 1 indicates low visibility, while 199 indicates very high visibility.
Just three journals contributed 86% of the papers referenced digitally. The most popular articles were classified as “original research” and fell into the categories of “evaluation of treatment outcomes”, “growth”, “side-effects”, and “quality of life”. There was no association of visibility, as judged by AAS, with publication date or authorship.
What was the singular most “popular” article? It was a work from 2016 on pain control using a micropulse vibration device, published in the Angle Orthodontist; it received an AAS score of 196 (out of a possible 199).
The authors reported no association between AAS and citations in Scopus, one measure of peer-review scholarly citations, a traditional measure of the impact of research publications.
WHAT THE PROFESSORS THINK
The authors address an important and very timely topic. The traditional definition of impact factor is a measure of how often an paper is cited by other articles published in peer-reviewed journals. The concept of altmetrics moves outside of the academic sphere and into “real world exposure.”
The idea of almetrics has been around for nearly a decade now, but the recent surge in both the use and validation of social media outlets has re-focused the importance of both “alternative” sources of information and alternative ways to measure the impact of an idea or new knowledge.
Although there are several altmetric web applications, the use of Altmetric in this study appears to be reasonable. Gleaning results from multiple time points was appropriate. The association of AAS with Scopus data was also suitable as a means to compare Altmertic results with a more traditional measure of impact.
Only articles that have a doi (digitial object identifier) can be analyzed by Altmetric, and only a subset of Orthodontic journals were considered, so this investigation has limitations. Its real value is not so much in which articles were captured, but in demonstrating the methodology.
So what do these results really mean for Orthodontists?
Knowing what the popular press tells our patients about Orthodontics matters. That fact is not really new information. What is interesting is that there are simple and free ways to track topics and their exposure to the public. For example, one can download a browser plugin for free and then use it to instantly see if an article you have read has made it into the public domain.
You can investigate or try some of those tools here:
For the practicing Orthodontist confronted by new controversies and technologies, it is simply both practical and good practice to have a grasp not just on the best evidence, but also on what is being presented to our patients by way of both traditional and social media.
It is also informative that the most valued articles, as judged by traditional academic metrics, are not necessarily the most widely-read. That fact too may not really be new information. It is information that may continue to find relevance, however, as social media expands and new ways to spread knowledge develop more rapidly .
Article Reviewed: Livas C. & Delli, K. Looking Beyond Traditional Metrics in Orthodontics: An Altmetric Study on the Most Discussed Articles on the Web. Eur J Orthod. 2017.
BY TUNG T. NGUYEN, DMD, MS & HUGO DE CLERK MS, PHD
In 2008, an innovative approach to the treatment of Class III skeletal malocclusions in growing patients was introduced by Hugo De Clerk. Bone Anchored Maxillary Protraction (BAMP) uses intra-oral skeletal plates and intermaxillary elastics (IME) to produce true orthopedic changes by protracting the maxilla and redirecting growth of the mandible, without dentoalveolar side-effect.(1)
The purpose of this clinical multi-part series is to summarize 8 years of clinical research on BAMP and give clinicians the tools to apply this protocol to their daily practice.
Class III malocclusions are among the most difficult to treat, with a large percentage of these patients requiring orthognathic surgery after mandibular growth is complete (after 16-18 years of age). Ideally, the option of a successful treatment approach that avoids surgery is needed. Such a treatment would:
Conventional treatment for young Class III patients often involves extra-oral devices designed to either increase maxillary length or restrain mandibular growth. Both approaches have had limited success due to undesirable dentoalveolar movements, limited skeletal changes, poor compliance, or relapse of dental movements.
Even with appliance modifications to minimize tooth movement and maximize orthopedic correction, some dentoalveolar side-effects are inevitable because these appliances are attached to the teeth. In addition, compliance is critical for success with these treatment modalities. Unfortunately, compliance proves to be difficult, as these cumbersome and socially stigmatizing extra-oral devices require 12-18 hrs of wear per day. Even with good compliance, it is difficult to maintain the correction: 25% to 33% of these patients experience post-treatment relapse within a year.(2)
With Bone Anchored Maxillary Protraction, patient compliance was improved due to the discreet nature of intra-oral elastics compared to the cumbersome extra-oral headgear. In addition, our studies showed BAMP was significantly more effective than the current gold standard for early treatment of Class III and can be implemented at a later age.(3)
In this, Part I of our BAMP Series, we will discuss the background and some of the existing evidence for the efficacy of this treatment modality. In later parts, we will discuss the clinical technique, tips, and strategies for managing complications.
One of our initial studies involved the 3D analysis of treatment outcomes for BAMP. Twenty-five consecutive Class III patients were enrolled in the study.(4) Using 3D registration of initial and final Cone Beam Computed Tomography (CBCT) for patients treated using the BAMP protocol, we evaluated orthopedic changes in the maxilla, mandible, and glenoid fossa.
Using the BAMP protocol, we saw an average anterior displacement in the maxilla by approximately 3.7mm with a range from 1.5mm to as high as 8.5mm. One explanation for the high variations in treatment response between patients might be due to the diversity of the original malocclusions. Some of the Class III patients presented with a severe -5mm overjet while others manifested a mild edge to edge incisor relationship. Other reasons for the high variation in treatment response include compliance with elastics, age, skeletal malocclusion, and maturation of the cranial sutures at the start of treatment.
We also saw forward The displacement of zygoma and midface by approximately 3.7mm, a phenomenon that rarely occurs with other treatment modalities. To explain this phenomenon, we examined the circummaxillary sutures and saw that the BAMP protocol resulted distraction of many of these circummaxillary sutures. It may be plausible that a constant force from the elastics, when applied before sutural maturation can effectively produce distraction of these sutures resulting in the forward displace of the entire midface. Recent animal studies have shown that continuous force application is more effective at expanding the sutures when compared to intermittent forces.(5)
The changes in the anterior mandibular region were more variable in both magnitude and direction. Many subjects exhibited a distal displacement of the chin, while some continued to grow in a normal forward direction.(6) While the anterior position of the chin stay relatively the same throughout the course of treatment (-0.5mm), this was significant when compared against matched untreated Class III subjects, who showed an mean forward growth of 2.2mm during the same time interval.(1)
It is also interesting to note that the BAMP protocol did not restrain growth of the mandible - but instead, it altered the direction of mandibular growth by closing the gonial angle and distalizing the posterior ramus and condyles.(6) The glenoid fossa remodeled to adapt to the new position of the condyle. While these findings are promising; long term studies are needed to evaluate the stability of this compensatory mechanism as well as the health of the temporomandibular joint complex.
In summary, BAMP is a promising protocol for true orthopedic treatment, one that has the potential to reduce the need for orthognathic surgery in growing Class III patients.
In Part II of our BAMP series, we will address the BAMP clinical technique in detail.
BY DAVID M. SARVER, DMD, MS
An eye-tracking study from The Ohio State University published in the AJO-DO provides clinicians new data to help them understand how smile esthetics interact with overall facial esthetics.
In the study, faces of varying attractiveness (“attractive”, “average”, or “unattractive”) were paired with dentitions that reflected malocclusions with a dental attractiveness ranging from 3-7 on the IOTN-AC scale. In this way, attractive faces could be paired with unattractive teeth, for example.
66 lay persons viewed 15 different combinations of faces with the teeth visible only within the framework of the smile. All of the faces were those of Caucasian women, and all participants were 18 - 30 year old Caucasians, in an effort to control for any possible other-race or age effects in terms of perception.
Objective eye-tracking hardware and software was used to evaluate what parts of the face participants spent the most time viewing during a 3 second exposure to each face. Interestingly, participants were not told that the purpose of the study was to evaluate dental or facial esthetics until after their participation.
Both eye fixation duration (time spent looking at one part of the face) and eye fixation density (how many times one part of the face was viewed) differed depending on the attractiveness of the face, the attractiveness of the dentition, the region of the face, and the gender of the participant.
For all the participants, more attention was focused on the mouth as the dentition became more unattractive.
For female participants, a significantly greater density and duration of gaze was focused on the mouth with the combination of an attractive face paired with an unattractive smile.
WHAT THE PROFESSOR THINKS
The study design is appropriate and used validated techniques that generate objective data for the very subjective field of facial esthetics. Using a specific age and ethnicity demographic, as well as an age, gender, and race restricted set of faces as stimuli is appropriate since it helps to control for some well-established potential confounders of judging facial attractiveness.
Finally, deceiving participants as to the nature of the eye-tracking task was clever. In this way, participants were not biased. Instead, these eye tracking data represent the “unconscious” judgement of facial attractiveness, which is ultimately the way most of our patients are judged most often after treatment.
This study has some interesting implications for the clinician who is interested in the very best communication with patients when it comes to the complicated topic of facial and dental esthetics:
Article Reviewed: Johnson EK et al. Role of facial attractiveness in patients with slight-to-borderline treatment need according to the Aesthetic Component of the Index of Orthodontic Treatment Need as judged by eye tracking. Am J Orthod Dentofacial Orthop. 2017; 151 (2) 297-310.
Reference: Sarver DM. Enameloplasty and Esthetic Finishing in Orthodontics—Identification and Treatment of Microesthetic Features in Orthodontics Part 1. J Esthet Restor Dent. 2011; 23 296-302.
Risky Business: Is Root Resorption More Likely with Fixed or Removable Appliances? The Latest Evidence Might Surprise You. . .
BY SYLVIA A. FRAZIER-BOWERS , DDS, PhD
The authors of Orthodontically-induced external apical root resorption in patients treated with fixed appliances vs. removable aligners, present a thoughtful and relevant clinical study that investigates the relationship of orthodontically induced external root resorption (OIERR) with the use of two different orthodontic treatment modalities (fixed appliances versus Invisalign®).
The objective of this case-control study was to determine if an association exists between OIEARR, appliance type, radiographic, clinical, and genetic factors using a backward stepwise conditional logistic regression analysis. OIEARR Cases and controls were selected in a non-random fashion from a private practice and a university clinic. OIEARR was defined as >2mm resorption of at least one incisor after completion of treatment, as judged using panoramic and lateral radiographs.
For each of the 372 participants, 12 clinical variables were assessed as well as polymorphisms in 3 genes, Interleukin 1B (IL1B), Interleukin 1 receptor agonist gene (IL1RN), and the osteopontin gene (SPP1).
The findings were as follows: of the 12 factors, two were associated with an increase of OIEARR, when controlling for the influence of all of the clinical and genetic factors recorded: 1) clinical case complexity (ABO discrepancy index) and 2) extent of incisor displacement in the sagittal plane. The results also showed that when subjects were homozygous for the T allele of the IL1RN gene (rs419598) they were 3 times as likely (or 2 times more likely) to experience root resorption.
Perhaps more importantly, the predisposition for OIEARR was similar whether using removable or fixed appliances. The odds ratio of 1.66 for predisposition of OIEARR in fixed versus removable appliances, in fact, indicates a modest but not statistically-confirmed increase in OIEARR associated with the use of removable versus fixed appliances.
WHAT THE PROFESSOR THINKS
The development of root resorption is a topic of growing interest to orthodontists; based on a nationwide survey conducted by the AAO, root resorption was considered a very important clinical issue by 60% of participating orthodontists. Accordingly, the study is timely and presents a unique view of an interesting question: Is root resorption more likely in a cohort with specific genetic factors and treatment modalities?
The authors, therefore, conduct a study that may translate into the clinical/practical orthodontic setting as follows:
“Would I advise my patients that one appliance type carries less risk than another in the development of root resorption?”
Based on the authors’ analyses, it is clear that the patients studied developed OIEARR at comparable rates with fixed or removable appliances. This finding is quite illuminating since anecdotally the assumption is that removable appliances may be gentler in terms of orthodontic tooth movement and lead to less root resorption.
This study ranks modestly in the hierarchy of study effectiveness. Given the retrospective design, systematic (non-random) factors may have determined treatment choice with removable versus fixed appliances. Also, the analysis considers a high number of variables that may be inter-correlated. In other words, it is likely that several of these factors actually cluster together and they are not independent, which could possibly change the relationship of clinical outcome and etiology.
The bottom line is that this study provides an important contribution to our ever-changing understanding of the relationship between specific clinical, genetic, and treatment factors on adverse treatment outcomes, such as root resorption (see the Figure above).
The take-home message when you go into the office on Monday morning is that orthodontically-induced root resorption happens more often than we may imagine, regardless of appliance type.
The simple notion that changing orthodontic treatment modality may decrease the risk of root resorption is not supported, based on the evidence here. Given advances in genomic studies, we can speculate that a combination of factors lead to the development of root resorption, with the problem being a defect in the repair mechanism of those who develop moderate or severe root resorption. The promise of more refined genotype-phenotype correlations that provide a practical tool to predict the risk of root resorption is foreseeable.
Article Reviewed: Iglesias-Linares et al. Orthodontically induced external apical root resorption in patients treated with fixed appliances vs removable aligners. The Angle Orthodontist. January 2017.