Orthodontics - A Quarterly Newsletter on Dental SpecialtiesJADA Specialty Scan

Mouth breathing and occlusion

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Clinicians have long perceived the association between mouth breathing and occlusal traits, including flawed facial form. Sleep apnea, the most extreme type of mouth breathing (MB), has gained greater attention in recent years and increased orthodontists’ interest.

Although its role in abnormal dentofacial growth is well-documented, the body of research has generated controversy about whether MB is associated with dental arch deformities. Countering much of the literature about how normalization of respiration through removal of obstructions in the upper airway can promote normal facial growth, some cohort studies have found no differences in the dental arch morphology of young children treated for tonsillectomy and adenoidectomy. As a result, the efficacy of surgical treatment in achieving normal breathing and dental arch and palatal development is called into question.

Noting that previous cohort studies had a nasal-breathing (NB) control group or included a small sample for the mouth-breathing control group, scientists publishing in the April 2014 issue of American Journal of Orthodontics and Dentofacial Orthopedics proposed that a longitudinal study with an untreated MB control group would better facilitate an understanding of the influence of mouth breathing and tonsillectomy and adenoidectomy on the dental arches of prepubescent children.

To follow up on that assumption, researchers conducted a one-year cohort study to test, during the children’s prepuburtal stage, the null hypotheses that:

The researchers used the dental casts of 95 children—49 mouth-breathers and 46 nasal-breathers. Twenty-four subjects from the 49 in the mouth-breathing group who had tonsillectomy and adenoidectomy were followed for one year and comprised the treated subgroup. The 25 mouth-breathing children who did not have surgery during the one-year observation period comprised the untreated control subgroup.

Patients in both the MB and NB groups were matched by chronologic age and skeletal maturation, were of the same ethnicity and lived in the same metropolitan area at the time of the sampling. The study casts were taken from all 95 children at baseline and at follow-up one year later.

Researchers found in their initial examinations that four of nine measurements taken were different between the MB and NB groups. Statistically significant differences were found for palatal depth, mandibular intercanine width, mandibular second molar width and mandibular dental arch length. At the start of the study, no statistically significant differences were found between the two MB groups—those slated for treatment and untreated controls.

Results showed that differences between baseline and one-year follow-up measurements were statistically significant for seven of nine measurements taken among untreated mouth-breathers. The children who were treated with tonsillectomy and adenoidectomy showed differences in only three measurements.

Among researcher’s major findings, the control group of children whose persistent obstruction was untreated during the one-year observational period showed less maxillary width gain as well as greater palatal depth development than those who had surgical normalization of respiration (tonsillectomy and adenoidectomy).

Also, after one year of uncontrolled severe MB, the palatal depth increased significantly. However, in the group of children who underwent tonsillectomy and adenoidectomy, the palatal vault was fairly stable, authors reported.

Authors said their finding suggest that for those with MB, the tendency of the palatal roof is to deepen, whereas a more normal growth pattern is established after tonsillectomy and adenoidectomy.

“Orthodontists should be alert to dental arch dimensional changes in prepubertal MB children,” authors advised. They added that referring to an otorhinolaryngologist may be beneficial in controlling intra-arch dimensions.
“The tonsillectomy and adenoidectomy subgroup had a significantly different pattern of arch development compared with the untreated control subgroup,” they said.



Consulting Editor: Lee W. Graber, DDS, MS, MS, PhD
Diplomate, American Board of Orthodontics

How patients see a ‘normal’ appearance

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What is esthetically normal?

When it comes to facial appearance, clinicians and patients have different opinions for different reasons. The literature shows that normality from a traditional clinician-based viewpoint, founded on measurements and principles defining ideal facial and occlusal proportions, is useful though not prescriptive.

“Knowledge of what each patient perceives as normal is paramount before treatment planning,” authors of a study published in the March 2014 issue of the American Journal of Orthodontics and Dentofacial Orthopedics said.  

Although neither doctor nor patient should override the other when treatment decisions are made, little research has explored patients’ views about what constitutes normal dentofacial features, the UK-based scientists reported.

To examine the concept of normality from the orthodontic patient’s perspective, they conducted a qualitative study by interviewing adults attending orthodontic consultations for a dentofacial abnormality. Their sample included patients whose plans were to pursue one among the following:

From the answers subjects provided during the interviews, scientists learned patients had certain concepts of a normal dentofacial appearance. Their perspectives fell into three themes: components of dentofacial normality, biopsychosocial impact of dentofacial abnormality and factors influencing patients’ conceptualization of dentofacial normality.

When reflecting on their own concerns, patients fixated on a particular dentofacial feature that they thought was not normal. Features cited were increased gingival show, grossly incompetent lips, increased overjet, traumatic overbite, reverse overjet with a prognathic mandible retrognathic mandible, dental crowding, dental spacing, changes in the dental appearance over time and anterior open bite.

Patients described what was normal from the perspective of their own malocclusions. Scientists observed a biopsychosocial impact of dentofacial abnormality among the subjects, with stigma playing a substantial role. Some who reported difficulty or pain during chewing also alluded to the stigma associated with the dentofacial abnormality and its negative effect on their social interactions and well-being.

They formed their ideas about what is and isn’t normal from personal observations in conjunction with the external influences of family and friends and appearances in the media.  
 “The negative effects described were biological, psychological and social, with significant overlaps between these domains,” authors noted in discussion. “It is not possible to state that one area has overriding importance because the data show that some people value media representations of appearance, whereas others see their close relatives’ views as more critical. However, it is important to understand the areas that can play a role in these conceptualizations to deepen the understanding of how orthodontic patients come to their own views.”

Study authors report their results could have implications for orthodontic treatment as a whole and called for more investigation in light of their findings.

“The potential for discord between the clinician’s and the patient’s views of normality and subsequently what is deemed to require treatment should be explored,” they said among conclusions.


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Maximizing the speed of tooth movement

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The degree of applied stress and whether the patient is in a growth phase during treatment influence tooth movement speed, a new study finds. Published in the April 2014 issue of the American Journal of Orthodontics and Dentofacial Orthopedics, its authors, from the University of Missouri and the University of Nebraska created a mathematical model correlating the speed of tooth movement and applied mechanics.

“Previous reviews of the literature on optimal mechanics for maximizing the speed of tooth movement have demonstrated the paucity of data on this topic,” they said, citing limited quantitative data in the dental literature.

To better understand variables affecting tooth movement, the scientists collected data for 82 maxillary canines in 41 patients treated at the University of Missouri Kansas City Graduate Orthodontic Clinic. Each subject required bilateral maxillary canine retraction into extracted maxillary first premolar sites.

While retracting the teeth for 84 days at estimated stresses of 4, 13, 26, 52 and 78 kPa (A kilopascal (kPa) is a metric measurement unit of pressure), the scientists made dental impressions at 1 to 14 day intervals, resulting in nine or 10 dental casts per subject.

The scientists then used the casts to evaluate tooth movement.

For each tooth, movement in three linear aspects (distal, lateral and extrusion) and three angular aspects (distal crown tip, lateral crown torque and distopalatal rotation) were plotted versus time to assess the nature and amount of movement during the study period. The slope of the movement versus the time plot showed the speed.

Changes in craniofacial growth and height measurements during treatment were used to determine the growth status of subjects, who were then classified as growers or nongrowers. Of the 30 growers, 17 were female. Seven of the 11 nongrowers were female.

Overall the greatest tooth movement occurred distally and increased linearly with time. On average, the teeth of growers moved 1.6 times faster. Speeds ranged from 0.016 to 0.109 millimeters per day in growers and 0.012 to 0.066 mm per day in nongrowers.

Although average speeds of distal tooth movement increased logarithmically with stress, the raw data showed that only 47 percent in growers and 34 percent in nongrowers of the variances in speed of distal tooth movement were explained by applied stress.

“The most remarkable unexpected and clinically important differences were seen for distopalatal rotation of the teeth moved by 78kPa, where the constrained conditions of the appliances were apparently outstripped …,” authors commented in discussion.

The study showed significantly faster speeds of distal tooth movement from stresses between 26kPa and 78kPa compared with lower stresses. This finding was contrary to previous predictions that 7 to 14 kPa might move teeth fastest. They added that such findings suggest that maxillary canine movement from this range of stresses is more efficient (faster for less load) than other previously published theoretical predictions.

The study demonstrated as much as a 9:1 difference in tooth movement speed between patients and was among findings substantiating authors’ call for further studies using other variables to improve predictions of the rate of orthodontic tooth movement.

This fits in with a goal of individually optimizing treatment protocols to improve results while decreasing active orthodontic treatment time.



Wear time and orthodontic appliances

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Is it unrealistic to expect patients to wear removal appliances 14 hours per day?

The results of a study published in the January 2014 issue of The Angle Orthodontist show it may be.

Scientists in Switzerland and Germany interested in patient compliance monitored 45 patients (20 females and 25 males) over 186 days to determine wear times and the potential influences of age and gender.

To accomplish this investigation, when compliance was considered particularly important, a measuring device was embedded in the orthodontic appliances of patients treated in a private orthodontic practice. Both the patients and their parents were informed about the presence and function of the measuring microchip.

Fourteen of the subjects required functional treatment and were instructed to wear their appliances for 14 hours per day. The remaining 31 were instructed to wear passive appliances for retention. Seven of these 31 were instructed to wear the retainer for 14 hours per day and the remaining 24 were prescribed eight-hour wear times per day.

Scientists found that despite the fact that patients and parents were informed about the recording of actual wear time, compliance times were similar for the two groups prescribed distinctly different wear times—14 hours per day versus eight hours per day. No matter what the prescription, patients wore appliances approximately nine hours per day.

Overall, the median wear per day relative to prescription was 62.5 percent for those patients given14 hour per day prescriptions and 112.5 percent for those with an eight-hour per day prescription.

“Namely, it was insufficient for functional appliance treatment, while it was sufficient for retention of treatment results,” authors reported. They added that although the 14 hours per day regime is widely accepted for effective functional orthodontic treatment, “there is no solid evidence regarding the optimal wear time for a successful treatment result.”

Although there was high individual variation, with eight of the subjects wearing their appliances less than two hours a day and six of them not wearing their appliances at all, increasing age negatively affected patient compliance but gender did not have a significant influence in this study.


The template calls for the image at 160 by 160 but adjustments can be made

CS OrthoTrac Cloud
With CS OrthoTrac Cloud practice management software, you benefit from a proven platform that has helped orthodontists build and maintain efficient practices for over 30 years—without the associated IT infrastructure and server costs. Access information anytime, anywhere from a variety of devices; all while knowing your critical patient files are being securely backed up and maintained by Carestream Dental.

ORTHOTRACCloud#Features and Benefits


What is Specialty Scan?

This is one in a series of quarterly newsletters updating dentists on selected specialties in dentistry. Information presented is aggregated and summarized from previously published materials, each item attributed to its publication of origin. This issue of JADA Specialty Scan focuses on orthodontics, the second in the series on this topic for 2014. Other Specialty Scan issues are devoted to prosthodontics, periodontics, endodontics and oral and maxillofacial radiology. The ADA has engaged the specialty organizations in these areas as well as its own divisions of Science and Legal to assist with these newsletters. We welcome your feedback on this and all Specialty Scan issues.

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