The Orthodontics Professors
the latest in contemporary & evidence-based orthodontics
First, Do No Harm: Are White Spot Lesions Less Likely to Develop with Aligners? This Study Says Yes.
BY TATE H. JACKSON & WILLIAM V. GIERIE
Is oral health better for patients treated with clear aligner therapy? A retrospective study from Texas A&M set out to address that question by comparing the incidence of White Spot Lesions (WSL’s) in two groups of consecutively-treated patients.
The aligner group contained 244 patients, while the group treated with braces included 204 patients. 85% of the aligner group were treated in a single private practice, while 52% of the braces group were treated in a single academic setting. There was no statistically significant difference in the gender or age of each group (both had a mean of ~30 years with a standard deviation of 11.5 to 14 years), but there was a difference in treatment duration, with the aligner group treated in less time (1.5 years vs. 2.5 years for braces).
At the end of treatment, the aligner group demonstrated a very low incidence of new WSLs, 1.2%, while the group treated with braces had an incidence of 25.7%. For both groups, maxillary teeth were more likely to be affected. Not surprisingly, WSL incidence was lower in the private setting, although the difference in incidence between groups (aligners vs. braces) was consistent in both the academic and private settings.
WHAT THE PROFESSORS THINK
Although this study suffers from the fact that it is observational and retrospective, there are a couple of key insights to note.
Both groups, the aligner group and the braces group, started with a similar pre-treatment prevalence of WSLs : 9% for the aligner group and 10% for the braces group, suggesting that the natural incidence of WSLs in these patients was similar before treatment began.
With treatment, only 3 out of 244 aligner patients developed new WSLs, while 52 of 204 patients in braces group did.
Given the incredibly low incidence of new WSLs in the aligner group, the authors were wise to only analyze risk factors for developing WSLs in the braces group. As expected, 1) poor oral hygiene that worsened and 2) longer treatment time both increased the risk of WSL development.
To most orthodontists in practice these results will be no surprise. Using removable appliances can allow for better oral hygiene – and thus aligners are less likely to be associated with WSL formation.
So, does that mean one might use this study to support the use of clear aligner therapy in any patient simply because their hygiene is poor? Certainly not based on that single factor alone. The authors correctly point out that this study does not account for the complexity of the malocclusion or specific treatment mechanics needed.
In this study, aligner patients were more likely to improve their oral hygiene during treatment, while braces patients were more likely to worsen. Wearing aligners requires compliance for success – just like oral hygiene. So, are patients who successfully wear aligners more capable of good oral hygiene anyway? This study does not address that question directly, but it does suggest that it might be true.
In practice, these data can be used to better communicate with the healthy motivated patient who is concerned about their individual risk for WSLs:
What about the patient who is not motivated? Should aligners be considered for patients who already have WSLs because their risk of new lesions is lower with aligners?
Article Reviewed: Peter H. Buschang; David Chastain; Cameron L. Keylor; Doug Crosby; Katie C. Julien. Incidence of white spot lesions among patients treated with clear aligners and traditional braces. Angle Orthodontist. Online 2018.
BY MATTHEW LARSON & TATE H. JACKSON
80 patients being treated at the Texas A&M School of Dentistry enrolled in this randomized trial to test whether daily or weekly text message reminders might better improve oral hygiene. At the start of the study, all patients had been in upper and lower fixed appliances for at least 4 weeks, spoke English, were between the ages of 12 and 17 years, and were more than 6 months from the end of active treatment.
Patients (not their parents) received texts through a third-party company that provides such services. In that way, the randomized groups could be blinded from the study authors. Patients received one of three types of text messages: 1) oral hygiene texts (e.g. “Don’t forget to brush your teeth twice a day!’’), 2) shorter treatment time texts (e.g. “Your time in braces will be shorter if you keep your mouth very clean!”), and 3) motivational texts (e.g. “Research shows that a better smile leads to better-paying jobs”).
After 8 weeks of text messages, bleeding, plaque, and gingival indices were all measured by a single blinded examiner. All indices were all significantly lower for the daily text group compared to the weekly text. The largest difference between groups was found in the bleeding index, where number of sites with bleeding on probing decreased 48% in the daily group but only 27% in the weekly group.
When surveyed, 97% of patients thought that text messages were helpful, and 70% preferred texts in the evening (7-9PM was the most preferred time). In regards to patient preference on texting frequency, 57% reported they preferred text reminders daily or twice a day, while an additional 20% preferred 3-4 times a week. Texts related to a reduction in treatment time were reported by patients to be most motivational.
WHAT THE PROFESSORS THINK
This study was well-designed. The use of a third-party company to deliver the text messages was helpful in two ways. First, it allowed for better blinding; the clinicians treating the patients were not responsible for sending the reminder messages. Second, the use of currently-available technology through this service makes the results more likely to be clinically relevant.
Although overall well-designed, there are also a few limitations to be discussed. First, it is always difficult observing oral hygiene in studies due to the Hawthorne Effect – oral hygiene will typically improve to some degree simply because patients are enrolled in a study. Also, the daily messaging group had slightly lower periodontal indices at baseline, although only the plaque index was statistically significant. These limitations likely do not change the validity of the results, but a slightly lower overall improvement may be seen in private practice.
Although the use of daily text messages only marginally increased patient oral health, the study was constructed in such a way as to provide helpful data to practicing orthodontists. Nearly all orthodontists already stress the importance of daily compliance with hygiene, elastics, and diet – this study supports those statements and leverages current technology to help support patients in those areas. By using multiple messages and by surveying patients regarding message preference, the results of this randomized trial were made more informative.
Importantly, the patients themselves received the text message reminders, and the patients reported their preferences, not their parents. In an age when the majority of teenagers have a cell phone, this aspect of the study design is critical.
So, for an orthodontist trying to motivate a teenager in braces, what do these data tells us?
Article Reviewed: Mike C. Ross; Phillip M. Campbell; Larry P. Tadlock; Reginald W. Taylor; Peter H. Buschang. Effect of automated messaging on oral hygiene in adolescent orthodontic patients: A randomized controlled trial. Angle Orthodontist. Online 2018.
A Tribute to Prof – Sarver, Fields, Larson, Vig, Turpin, McNamara, Johnston, & The Professors Remember Him in Their Own Words
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BY TATE H JACKSON AND TUNG T NGUYEN
A group at the University of California at Los Angeles (UCLA) have conducted a retrospective study to evaluate how rapid palatal expansion with mini-implants placed in the palate works in post-pubertal patients.
15 participants (9 female) with ages ranging from 13.9 to 26.2 years were all consecutively-treated with a modified Wilmes-style hybrid tooth-borne / mini-implant borne maxillary expansion appliance. 14 of these patients were in dental crossbite. The need for expansion was determined by measuring and comparing maxillary and mandibular casts, not by comparison to population norms.
All participants were treated with the hybrid tooth/mini-implant expander alone; no other appliances were in place during expansion. The authors report that all mini-implants were placed in the posterior palate with bicortical anchorage.
The hybrid expander was turned twice each day (0.25mm per turn) until “a diastema appeared” and then just once per day. The expansion devices were maintained for 3 months following the end of activation.
Cone-beam CT (CBCT) images were obtained for each participant before treatment and within 3 weeks of the end of active expansion, but before any additional active appliances were placed.
After cranial base superimposition of the pre- and post-expansion volumes, transverse expansion was measured in coronal sections at the level of the Upper Zygoma (frontozygomatic suture), Lower Zygoma (zygomaticomaxillary suture), and Maxillary Molars.
Expansion resulted in little transverse change at the Upper Zygoma [mean of 0.52mm (SD 0.37mm]. An average of 4.62mm (SD 1.33mm) of expansion occurred at the Lower Zygoma, and 8.33mm (SD 2.29mm) occurred at the Molar.
Taken together, for every 1mm of transverse expansion, the zygomaticomaxillary complex rotated outward by 0.6 degrees on each side.
Stated another way, an average of 6.8mm in expansion at the level of the jackscrew resulted in an average of 8.33mm of expansion at the molars, with an average of 2 degrees of total outward tipping of the molars on each side. It is important to note that tipping of the molars was highly variable, with standard deviations reported that were nearly double the mean.
WHAT THE PROFESSORS THINK
The consecutive case series reported in this paper represents a well-constructed study, despite the limitations of retrospective data analysis. Superimposition of CBCT volumes and analyses of transverse changes were founded on validated methods, and reliability of the measurement made were adequately measured and reported.
It is unfortunate that the authors did not report the rate of adverse outcomes for the participants in the study. e.g. Did any of the mini-implants fail?
The paper focused a bit more on theoretical biomechanical outcomes, such as where the center of rotation might be for the skeletal units involved, than is likely to be helpful for practicing orthodontists.
Some practical points can be gleaned, however:
1. When using a hybrid bone/tooth borne maxillary expander in later-adolescent to early adult patients, you should expect some “tipping” of the molars. That tipping happens due to a combination of skeletal rotation, and to a lesser degree, change in inclination of the molars.
2. Based on this study alone, the amount of molar tipping that occurs can be quite variable. As little as 4 degrees of total tipping might occur, or as much as 10 degrees. From previously published studies, the amount of tipping using mini-implants should certainly be expected to be less than with tooth-borne expansion alone, however. (1, 2)
3. In order to give a patient good estimates of the likelihood of both success and adverse outcomes with this treatment, more data are needed.
These data represent good initial guide-points for orthodontists in practice and suggest that mini-implant maxillary expansion should be considered in younger non-growing patients with skeletal transverse issues.
The prudent orthodontist, however, will communicate with the patient / parents that although the procedure is a great alternative to more invasive surgery, it still carries with it some real risk and uncertainty at this time.
Article Reviewed: Cantarell D, et al. Midfacial changes in the coronal plane induced by microimplant-supported skeletal expander, studied with cone-beam computed tomography images. Am J Orthod Dentofac Orthop 2018; 154:337-345 (Sept).
1) Lin L, Ahn HW, Kim SJ, Moon SC, Kim SH, Nelson G. Tooth-borne vs bone-borne rapid maxillary expanders in late adolescence. Angle Orthod. 2015;85:253–262
2) Mosleh MI, Kaddah MA, Abd ElSayed FA, ElSayed HS. Comparison of transverse changes during maxillary expansion with 4-point bone-borne and tooth-borne maxillary expanders. Am J Orthod Dentofacial Orthop. 2015;148:599–607.
Click the image below to read Dr. Proffit and Dr. Ackerman's review of the sensationalist book, Jaws.
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Tate H. Jackson, DDS, MS