The Orthodontics Professors
the latest in contemporary & evidence-based orthodontics
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.
BY TATE H. JACKSON AND CLARKE STEVENS
A study just published in the Angle Orthodontist has analyzed 419,363 tweets, shared publicly regarding the patient experience with either traditional fixed appliances or Invisalign®. The data were collected over a period of five months from April to September in 2015 and analyzed by sentiment analysis using Naïve Bayes classifiers.
Tweets were identified by the use of the keywords “braces” or “Invisalign” and filtered using software so that content irrelevant to orthodontics (braces as a term for suspenders in fashion, for example) was excluded. All tweets relevant to orthodontics with either keyword were then classified in sentiment as positive, negative, neutral, or as an advertisement.
Overall, more tweets about orthodontic treatment were positive (62%) than negative (38%). There was no statistically significant difference in the proportion of positive tweets when comparing traditional braces to Invisalign®. More individuals tweeted about braces than Invisalign®, and 1/3 of all the tweets involving Invisalign® were classified as advertisements. Generally, positive tweets most often focused on gratitude while negative tweets most often focused on pain.
WHAT THE PROFESSORS THINK
The topic and methodology of this study are certainly relevant to those practicing in the era of social media. The use of a simplified sentiment analysis was evidence-based, and the authors used adequate search terms and a human-defined pool of categorized terms of adequate size to train the software for the larger analysis that took place.
The authors did not analyze if tweets originated from individuals associated with an orthodontics practice. Although that may be impossible to do effectively, it is important to interpret the data with that fact in mind.
Although this study only presents data from one form of social media, it does have some interesting ramifications for practicing orthodontists.
First, the fact that more than 400,000 tweets published over a five month period involved orthodontic treatment reinforces the power of social media in the public discourse relative to orthodontics.
Second, the majority of tweets were positive in nature, a point that might reassure orthodontists that the profession is viewed favorably. The magnitude of positive sentiment reported (62%) can serve as a sort of evidence-based benchmark for individual practices. If an analysis of a practices’ social media references shows a lower proportion of positive comments, it might be an objective reason for concern on the part of the practice.
Third, it is also interesting to note that despite the fact that there were more tweets related to traditional braces overall, there was a much higher proportion of advertising related to Invisalign®.
33% of all tweets related to Invisalign® were advertisements, compared to only 7% for braces. Again, for clinicians in practice who want some sort of evidence-based benchmark related to the density of advertising for either traditional braces or Invisalign® using social media, these data give some insight.
Article Reviewed: Noll et. al. Twitter analysis of the orthodontic patient experience with braces vs. Invisalign. The Angle Orthodontist. Online Early, Jan 2017.
BY TATE H. JACKSON AND WILLIAM V. GIERIE
A study in the Angle Orthodontist has surveyed 1,000 General Dentists and 1,000 Orthodontists – drawn from a list of Invisalign® providers on the company’s website. Those surveyed were asked to rate their confidence using Invisalign® to treat six different cases for which intra-oral photographs were provided: a Deep Bite case, a Posterior Crossbite case, a Anterior Open Bite case, Mild Crowding case, a Severe Crowding case, and a Class II case. Additionally, both Orthodontists and General Dentists were asked about their various treatment planning (e.g. time spent with ClinChecks) and mechanics (e.g. use of Class II elastics or auxiliaries) tendencies with Invisalign®. Finally, demographic and training information, as well as experience in treating cases with Invisalign® was reported.
Overall, both Orthodontists and General Dentists were relatively confident in treating the four cases presented with Invisalign®. Interestingly, General Dentists were significantly more confident when it came to more complex cases: deep bite, severe crowding, and Class II. Orthodontists reported higher confidence in treating mild crowding than General Dentists.
Orthodontists were significantly more likely to spend more time reviewing ClinCheck set-ups and were more likely to use refinements and elastics as a part of treatment. Not surprisingly, Orthodontists reported more training and experience using Invisalign® and were more likely than General Dentists to tell patients that their malocclusion was too complex for Invisalign®.
WHAT THE PROFESSORS THINK
This article provides some data for practicing Orthodontists that might be of great use in discussing with patients why orthodontic care is specialized treatment – not just the appliance used to straighten teeth.
The use of a specific case records in conjunction with confidence ratings, and not just a survey self-report, gives these data some greater credibility. The use of intra-oral photographs alone had good rationale, since it provided a realistic version of the information that a General Dentist might consider when planning an Invisalign® case. The structure of the survey, asking respondents to give demographic and training information after completing the confidence ratings is helpful since it aids in avoiding bias when reporting confidence.
The fact that the response rate to the survey is not clearly reported is an unfortunate shortcoming of the study – one that, if clarified, would significantly improve the reliability of the results.
There are two pieces of information from this study that are most interesting and clinically relevant:
Article Reviewed: Best et al. Treatment management between orthodontist and general practitioners performing clear aligner therapy. Angle Orthodontist. Online Early Nov 2016.
Tate H. Jackson, DDS, MS