Orthodontics - A Quarterly Newsletter on Dental SpecialtiesJADA Specialty Scan

Predicting and preventing palatally displaced canine complications

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Clinicians want to prevent palatally displaced canines (PDCs) whenever possible because they’re often precursors of impacted canines. Impaction not only lengthens and complicates orthodontic treatment, but also increases costs, the risk of root resorption and potential tooth loss.

The body of dental literature suggests that the earlier applicable treatment is provided the better. With this evidence in mind, scientists at the University of Gothenburg, in Sweden, completed a randomized controlled trial in two parts. The topic — extraction of the deciduous canine as an interceptive treatment in children with palatal displaced canines — was explored in the first research stage to answer a central question: Shall we extract the deciduous canine or not? The second stage of research explored variables that might predict likely spontaneous eruption. The two studies were published in the September 2014 and February 2015 issues of the European Journal of Orthodontics.

In their first report, scientists compared the effect of interceptive extraction of the primary canine in children with unilateral or bilateral PDCs compared to a control group that didn’t undergo extractions. Their goals were to analyze whether extraction of the primary canines enables desired eruption of the PDCs and also to examine root resorption in adjacent teeth caused by PDCs.

Finding no previous studies assessing three-dimensional depth of impaction and related outcomes, they used cone beam computed tomography (CBCT) to investigate. Radiographic changes in tooth eruption between the extraction group (EG) and the control group (CG) at zero to six and six to 12 months after extraction of the deciduous canines were also assessed. As patients with both bilateral and unilateral PDCs were included in the study, the tooth rather than the patient was used as the unit of analysis.

Among the 67 children participating in the study (64% at 10-11 years old and 36% at 12-13 years old), significantly more spontaneous eruptions of the PDCs were found in the EG than in the CG. Scientists observed rates of 69% and 39%, respectively.

Scientists also found shorter average PDC eruption times in the EG, at 15.6 months. The average in the CG was 18.3 months. No significant differences in resorption of adjacent teeth were found between the two groups.

“The findings in the study show that extraction of the deciduous canine allows the PDCs to spontaneously correct in the majority of cases,” authors reported. Among conclusions, they said extraction of the deciduous canine in patients with PDC is an effective interceptive approach.

The trial was the first to the authors’ knowledge to assess the effect of such extractions using three-dimensional radiographic images, which provide a more accurate diagnosis of canine position and movement.

Avoiding surgical intervention by determining predictors for spontaneous eruption of PDCs was analyzed in part two of the scientists’ published research.

There are consequences to early removal and/or lack of removal of primary canines in the developing dentition with PDC. Although discomfort during and after extraction of the deciduous canine in patients with PDC has been reported to be low, some 42% of children in a previous study used analgesics, indicating post-extraction pain. Also, although previous evidence suggests that extraction of the deciduous canine is effective in patients with PDC, not all permanent canines erupt in spite of the intervention and some PDCs erupt even without the extraction. How is the clinician to decide?

Reasoning it desirable to identify which cases would most likely benefit from extraction, the scientists used CBCT to analyze how various factors affect the success rate and influence the length of time it takes for the canine to erupt when it does so successfully. They also aimed to learn the points at which interceptive extraction alone (i.e., without added surgical uncovering of the permanent canine and/or orthopedic palatal expansion) is not effective and the PDC parameters where eruption of the permanent canine will occur without interceptive extraction of the primary canine.

Analyzing the same patient group as in the phase one research, scientists found that the permanent canines erupt naturally more often in younger patients with a smaller mesioangular angle, shorter distance of the canine cusp tip to the dental arch plane and greater distance of the canine cusp tip to the midline. This is as researchers expected, with the more severe deviation from a normal eruption pattern having less success for solely early primary canine removal.*

The study provided definite cut-off points of four radiographic variables that were found to be predictive of whether or not the PDC would spontaneously emerge — canine cusp-midline, canine cusp tip-dental arch plane, mesioangular angle and age of the patient.   

“Extraction of the deciduous canine is the variable that affects the spontaneous eruption of the permanent canine most,” authors said among conclusions.

Read the original articles Part 1 and Part 2.

*Editor’s note: There are other studies that would suggest a program of orthopedic palatal expansion, coupled with early removal of the primary maxillary canines provides the most predictable positive outcome for significant palatally directed canines. This is especially true for patients who present with more severe PDCs, often associated with a relatively small maxilla and developing crowding. 


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

Managing impacted central incisors

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The incidence of developing impacted maxillary central incisors is relatively low, with the primary cause either obstruction (a midline supernumerary being the most common) or trauma. Either etiology presents a therapeutic challenge to the clinician. Patients with impacted upper front teeth face wide-ranging problems, if untreated. Problems can include: compromised appearance; oral function and speech; narrowing of available space for the incisor to erupt due to tipping of adjacent teeth; and a delayed or altered eruption path for the maxillary canine.

The three treatment options entail (1) extraction of the impacted tooth and future prosthetic replacement, (2) extraction of the tooth and lateral incisor substitution and (3) orthodontic movement of the impacted tooth in to the arch. Most clinicians avoid early extraction because the patients seeking treatment are very young. Interim prosthodontic solutions would be temporary and extraction of an impacted tooth would lead to bone loss in a potential future implant site.

Scientists in Israel interested in assessing patient and treatment factors influencing success and duration of the third option – orthodontic (surgical uncovering and limited fixed appliances) – conducted a study and published their findings in the March 2015 issue of the American Journal of Orthodontics and Dentofacial Orthopedics. Finding a lack of data concerning the success rate and duration of the orthodontic-surgical modality treatment of impacted central incisors, authors conducted their own study in a group of consecutively treated patients.

“The orthodontic-surgical solution aims for complete alignment of the natural teeth and requires no prosthodontic enhancement,” authors said. “The eruption of the impacted tooth draws the surrounding alveolar bone to produce a bony crest height and periodontium similar to those of the adjacent teeth.”

With a goal of providing accurate information to patients and parents, the scientists examined factors that may influence treatment success and duration. They compared the age, sex, etiology of impaction (trauma, obstruction, unknown), location of the impacted tooth and type of surgical exposure performed in 60 consecutive patients with 64 impacted incisors. The patients were treated between 2002 and 2007 at Hebrew University in Jerusalem and in the private practices of two of the authors.

Of the 60 subjects, 27 were classified as trauma-affected and 29 had obstructed incisors. The etiology was undetermined in four patients.

Treatment was considered successful if the incisor was brought into its place in the arch. Ninety percent of the cases, or 54 patients, were treated successfully. Six of the patients experienced failures.

The authors found that the only variable statistically significant for prognosis was the etiology. Permanent incisors impacted due to permanent root dilacerations, most often due to prior trauma to primary teeth, had a significantly higher risk for failure than those impacted due to obstruction. Treatment of impacted incisors with dilacerations was more than three months longer than for impactions caused by obstruction. Older patients required six more months of treatment, however the differences reached statistical significance only for the finishing stage of treatment when more complex movements, such as rotations, uprighting and torqueing were performed.

For total treatment time, the only variable with a significant impact was the initial height of the full impacted tooth. The higher and more displaced the impacted tooth, the longer the treatment was likely to be.

Of the six failures, five occurred in the dilacerated group. “The poorer prognosis for dilacerated incisors finds a cogent explanation in the fact that most orthodontists believe that this phenomenon is due to trauma,” authors said. “Other clinical sequelae related to trauma include ankylosis (fusion of the tooth to the bone) and invasive cervical root resorption, both of which are potent factors in the nonresponse of an affected tooth to orthodontic forces; hence the increased failure rate with dilacerations.”

Authors summed up their research with two primary conclusions:

  1. “The prognosis of orthodontic-surgical treatment for impacted incisors is good; however, failures do occur, particularly when the etiology for the impaction is dilacerations.”
  2. Treatment is relatively long — up to two years — and is significantly affected by the initial height of the impacted tooth.”   

The authors note that the treatment of an impacted central incisor is usually a “first phase of treatment” and is different than other “early” orthodontic treatment procedures as it does not decrease the customary overall treatment requirements and time for comprehensive (second phase) orthodontics.

Read the original article.


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Baby teeth and future orthodontic need

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Just because a child won’t keep his or her primary teeth doesn’t mean it doesn’t matter if they are straight or not. In fact, new research shows an important relationship between the deciduous dentition and orthodontic treatment need in the permanent dentition.

It’s long established that children with severely crooked teeth experience more bullying, poorer oral health-related quality of life and more dissatisfaction with their appearance. Identifying risk for orthodontic treatment need may assist clinicians in determining the timing of the most appropriate interventions.

Finding scarce research investigating the relationship between malocclusion in the deciduous dentition as a risk factor for orthodontic treatment need in the permanent dentition, a team of researchers from Australia, New Zealand and Brazil conducted a study with a prospective longitudinal approach. They published their findings in the April 2015 issue of the American Journal of Orthodontics and Dentofacial Orthopedics.

Combinations of malocclusion in the deciduous teeth and outcomes in the permanent teeth were compared. (Researchers found most previous studies did not evaluate the influence of the different types of malocclusion in the deciduous dentition on the later malocclusion.) Open bite, crossbite and canine malocclusion were assessed in the primary dentition of 359 children at six years of age and 339 adolescents at 12 years of age, representing 94.4% of those who were investigated at age six. After controlling for confounding factors, the researchers observed that malocclusion in children’s primary teeth at age six is a risk factor for orthodontic treatment need in the permanent dentition.

“Children with only open bite and those with concurrent open bite and canine malocclusion in the deciduous dentition had a greater need for both highly desirable and mandatory orthodontic treatment by age 12 than did children with no malocclusion at age six,” authors said. “Moreover, the combination of crossbite and open bite in the deciduous teeth was associated with mandatory orthodontic treatment need by age 12.”

In discussion they noted that their findings suggested a developmental etiology which prior studies have related to genetics, local factors like habits as well as caries. Noting that early intervention in aberrant growth patterns and undesirable local factors may help to mitigate adverse development, the authors stated, “Further investigation on the effectiveness of early orthodontic or orthopedic intervention in several types of malocclusion in the deciduous and mixed dentitions may improve our understanding of this complex association.”

Children with an apparent malocclusion at a young age should be monitored more frequently as their permanent teeth emerge so that parents or caregivers can better prepare for possible orthodontic treatment, they concluded. These recommendations would seem to parallel those of the American Association of Orthodontists that suggest an orthodontic evaluation no later than age seven. The authors also called for further studies to better understand the relationship of each type of malocclusion to orthodontic need.

“The changes in malocclusion from the deciduous to the permanent dentition highlight the need for longitudinal tracking. Since it is difficult to prevent malocclusion, more effort should be directed toward early effective treatment.”

Read the original article.


Better chewing ability after treatment

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Patients who have dentofacial deformities and receive orthognathic treatment or surgery perceive their chewing ability to be as good as patients without any orthodontic or orthognathic surgery needs, new research reports.

Scientists in Sweden, reporting in the February 2015 issue of the European Journal of Orthodontics, compared the self-estimated masticatory ability and clinically measured actual performance in 121 patients with dentofacial deformities before and after treatment to an age- and gender-matched control group. At baseline, the patients with dentofacial deformities rated their masticatory ability lower than the control group without treatment needs. They reported more difficulty in chewing meat, raw carrots, toffee and other foods.

Three years later treated patients reported similar levels of ability in chewing as those who never had a need for orthodontic treatment. Masticatory performance, as measured by the scientists, also increased significantly among the treated patients, though not to quite to the full level reached by the control group. The authors postulated that performance levels would have approached norms if the subjects had been tested after further post-surgical adaptation. Greatest positive performance changes were for those with initially presenting Class III and/or open bite. Authors found that the number of occlusal contacts and severity of overall symptoms of temporomandibular joint disorder influenced both masticatory ability and performance and that open bite had a negative effect on performance.

Read the original article.

AAO issues consumer alert

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The nationally syndicated news magazine “Inside Edition” alerted its audience to the dangers of “do-it-yourself” dentistry and orthodontics in an April 16 program available to viewers online. The segment informed viewers that attempts at self-care can result in the permanent loss of teeth and lifelong dental problems.

A consumer alert on the American Association of Orthodontists website includes a link to an editorial and blog posting published in the American Journal of Orthodontics and Dentofacial Orthopedics and an AAO press release linking to a photo showing the consequences experienced by a patient.

Capture high-resolution images with the CS 3500 intraoral scanner

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

With CS Solutions for Orthodontics, users have the option to create digital impressions with the CS 3500 intraoral scanner for use with new CS Model software.

The CS 3500 intraoral scanner acquires true color, 2D and 3D images without the need for a heater, powder or trolley system. The scanner features high-angulation scanning of up to 45 degrees and to a depth from -2 to +13 millimeters. It also includes an autoclavable tip available in two sizes, a smaller tip for children or adults with small mouths and a larger tip for adults, to ensure users adhere to the best practices for infection control.    
With the scanner, practitioners can capture high-resolution images digitally rather than using the putty associated with traditional impressions — eliminating the need for using impression material, pouring molds or waiting for stone models to set.

Once digital impressions are created, CS Model software takes basic distance measurements — including overjet, overbite, pressure map, arch length, tooth size, crowding measurement and more — to further improve clinicians’ diagnostic capabilities. CS Model enables orthodontists to quickly create digital models; review and store them electronically; and produce orthodontic appliances through preferred labs.

Creating digital models is an environmentally friendly solution that ensures that patients’ models are not damaged, lost or mixed up over time. Plus, CS Model gives practices access to all cases 24/7, without the need to access third-party storage via the Internet.

Digital models not only save time and money, but also serve as a powerful tool to engage patients in treatment planning and increase case acceptance.

For more information, click here.


CS Solutions for Orthodontics
With CS Solutions for Orthodontics, users have the option to create digital impressions with the CS 3500 intraoral scanner for use with new CS Model software. The CS 3500 intraoral scanner acquires true color, 2D and 3D images without the need for a heater, powder or trolley system.

For more information, click here.


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 2015. Other Specialty Scan issues are devoted to endodontics, oral and maxillofacial radiology, pediatric dentistry, periodontics and prosthodontics. The ADA has engaged the specialty organizations in these areas as well as its own Science Institute and Division of Legal Affairs to assist with these newsletters. We welcome feedback on this and all Specialty Scan issues.

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