Drs. Elliott M. Moskowitz, Ronniette C. Garcia, M. Bina Park, and Eleni Michailidis address the challenges and treatment of ectopic maxillary canines



Abstract

The management of frank maxillary canine impaction remains a challenge to the orthodontic clinician. Most frequently, maxillary canine impaction, particularly, palatally displaced impacted maxillary canines, will require adjunctive surgical procedures and subsequent orthodontic traction to successfully redirect these teeth into the dental arch. The pediatric dentist is in a unique position to identify ectopic maxillary permanent canine development (a predisposing factor for both maxillary lateral incisor root resorption and subsequent impaction of the canine itself) in the early mixed dentition. Early detection of ectopic developing maxillary canines can help to improve the overall prognosis for successful interceptive intervention aimed at redirecting the pre-eruptive ectopic canines to normal eruptive positions. The authors present their clinical observations of such interceptive efforts in their own practice following the treatment of a considerably large number of patients with varying degrees of detected ectopic maxillary canine development. Relatively high-level, evidence-based clinical trials conducted by other colleagues (which in some instances included both randomization and control groups) appear to validate the authors’ empirically derived clinical protocols aimed at intercepting potential maxillary canine impaction.

Introduction

Impacted maxillary canines are detected by pediatric dentists, general dentists, and orthodontists. Most impacted maxillary canines are symptomless, and many patients and parents of young patients are unaware of such impactions until they are informed of this clinical circumstance by a dentist. Frequently, the maxillary primary canine will still be present and, as such, poses far less of an esthetic issue than if the primary canine had exfoliated leaving an obvious space. The patient in Figure 1 was a 26-year-old woman who was unaware of the bilateral impacted maxillary canines (Figure 2) until they were detected by her general dentist after a routine clinical and radiographic examination. Frank impactions of maxillary canines represent a clinical situation most frequently requiring additional assistance in order to position these teeth into the dental arch. This additional assistance is generally a coordinated orthodontic and oral surgical/periodontal procedure. A number of important considerations include an evaluation of the feasibility and desirability of repositioning the impacted tooth in question into the dental arch, creating, if not already present, the required space in the dental arch to accommodate an impacted tooth; choice of a specific surgical procedure to uncover and place an appropriate orthodontic attachment, and the implementation of efficient orthodontic mechanotherapy and force application to successfully traction the impacted tooth into the dental arch with minimal potential damage to adjacent structures and the periodontium of the impacted tooth itself. Figure 3 depicts a relatively later stage of orthodontic treatment of the patient in Figure 1 after appropriate space had been created via orthodontics to accommodate the permanent maxillary canines, followed by a surgical exposure and placement of an orthodontic attachment, and subsequent alignment and detailing of individual tooth positions and inter-occlusal relationships (Figure 4) with both maxillary and mandibular fixed orthodontic appliances.

The aforementioned clinical considerations apply to frank impactions of maxillary permanent canines that are generally detected and treated after these teeth have been determined to be incapable of erupting without additional assistance. The orthodontist and pediatric dentist, however, are often in a position to evaluate pre-eruptive patterns including maxillary canine ectopic positions. Ectopic developmental pre-eruptive positions of permanent maxillary canines can lead to resorption of the roots of adjacent teeth (most notably, the maxillary lateral incisors) and future impactions of the maxillary permanent canines.1-3 It is the purpose of this article to explore the clinical opportunities available for redirecting ectopic maxillary permanent canine development with the overall intent of facilitating the normal eruption of these teeth.

Prevalence and etiology

The prevalence of maxillary canine impaction has a wide range and greatly depends upon ethnic and racial populations studied.  Becker has cited a number of studies in his text that included the lowest frequency reported in the literature in Japan at 0.27%, the United States at 0.92%, and the Icelandic population survey at 1.8%.4 Females have a markedly increased prevalence of impacted canines of approximately 2:1 found in some studies5 and in other studies even higher (3:1 found in a Welsh orthodontic group).6 Maxillary canine impaction seems to favor overwhelmingly palatally displaced positions as opposed to buccal vestibular positions.7 Prevalence rates of impaction studies have little practical significance (at least in the authors’ opinions) because orthodontic practices do not see representative samples of populations, but rather specific cohorts of individuals presenting with existing and perhaps co-variable factors influencing ectopic and impacted teeth. Consequently, individual orthodontic practitioners might see a far greater prevalence or incidence rate of impacted teeth in their practices than might be expected from results of epidemiological surveys.



Peck and Peck have presented compelling reasons to suspect genetic influences associated with ectopic and impacted maxillary canines.8 Others have suggested more of a “guidance” factor generally associated with either missing, peg-shaped, or displaced maxillary lateral incisors.9  Clearly, an expanded discussion of the possible etiology of palatally impacted maxillary canines is beyond the scope of this article, but suffice it to say that it is perfectly reasonable to presume that genetic influences (missing and small maxillary lateral incisors) might very well set an unfavorable environmental or local influence on the development of impacted maxillary canines that initially seek some form of “guidance” from the maxillary lateral incisor roots.

Efforts to redirect ectopically developing maxillary permanent canines

The authors, as well as other colleagues, have been interested in the clinical possibilities aimed at redirecting ectopically developing pre-eruptive positions of maxillary canines in an effort to avoid impactions that would require surgical exposures of these teeth at a later date. In addition, the redirection of severely ectopic maxillary canines could prevent root resorption of adjacent teeth, particularly, the maxillary lateral incisors. The key to clinical success in this particular area begins with early detection. Panoramic radiographs are useful screening images for detecting intraosseous ectopic canines as well as other potential issues. Missing or supernumerary teeth and pathology of odontogenic origin are often detected by such screening radiographs in the mixed dentition.



Several protocols have been recommended previously as proactive treatment recommendations intended to redirect developing ectopic maxillary canines. Kurol and others have recommended the removal of the maxillary primary canines with the intention of redirecting the maxillary permanent canines into better positions.10,11 More recently, several articles have been published advocating the removal of the maxillary primary canines and maxillary primary first molars (double primary teeth extraction procedure).12,13 The authors of the double primary teeth extraction technique claim a more profound intraosseous redirection of the ectopically developing maxillary canines.

Baccetti and colleagues have conducted clinical trials that treatment) comparing different treatment protocols intended to redirect ectopically developing maxillary canines.14-16 Their conclusions, to a great extent, mirror the authors’ clinical experience and empirically derived protocols that have focused on successfully redirecting ectopically developing maxillary canines to normal eruptive positions, thereby effectively intercepting potential maxillary canine impactions. Our clinical observations include:

1.    The strategy of removing the maxillary primary canines as a sole measure (as suggested by some orthodontists) with the intent of successfully redirecting the ectopic maxillary permanent canines to normal eruptive positions might very well appear to or actually encourage a more favorable maxillary permanent canine eruptive position in some instances, but has a limited success rate in cohorts of successive cases of pre-eruptive permanent maxillary canine ectopia in our practice.
 
2.    Combining procedures of maxillary primary canine removal (and maxillary primary first molar removal in selected instances) with maxillary expansion devices (with or without evidence of maxillary transverse issues) has produced the most favorable clinical outcomes (greater percentage of successfully erupted initially ectopic maxillary permanent canines).
  
3.    We estimate that the above “evidence-bolstered” clinical protocol entailing a more comprehensive targeted strategy aimed at addressing maxillary permanent canine ectopia can have a success rate of approximately 85% to 90% when applied to patients within a specified range of ectopic maxillary permanent canine inclination, mesial position, and degree of root development.
 
4.    The initial emphasis of the successful management of ectopic maxillary permanent canines must begin with early detection (early mixed dentition), observation when appropriate, and active clinical measures when required.

5.    Ectopic maxillary permanent canine eruptive development can be unpredictable, and “cookbook” approaches should be avoided for individual patients. Figure 5 is an intraoral view of a 10-year-old girl with a malocclusion in the mixed dentition. Figure 6, her panoramic radiograph, shows varying degrees of both maxillary and mandibular permanent canine ectopia. The patient’s parents declined orthodontic treatment, but returned 2 years later. Figure 7 is the panoramic radiographic image of the same patient with a far less complicated malocclusion with all permanent canines in excellent position. The obvious point is that certain
maxillary permanent canines with varying degrees of ectopia or adverse inclinations might autocorrect in their developmental paths in the absence of any form of orthodontic intervention.

6.    Axial inclinations, mesial position, and canine root development of ectopic maxillary permanent canines may serve as useful guides to determine the potential for either autocorrection or successful conservative pre-eruptive orthodontic guidance/intervention. Figure 8 is a panoramic radiograph of a young patient with ectopic maxillary canines with advanced root
development, severe axial inclinations, and migration past the mesial limit of the maxillary lateral incisor roots. In addition, large circumscribed radiolucent areas appear to surround each maxillary canine. Such adverse conditions provide a rather poor prognosis without a surgical exposure and subsequent orthodontic traction. Indeed, removal of the maxillary primary canines at this point proved to be ineffective, and the patient required a surgical exposure and orthodontic traction (Figure 9).    

Clinical Cases

Case 1
The patient, a 13-year-old boy, appears to have a relatively routine Class I malocclusion (Figure 10). The panoramic radiograph, however, reveals bilateral ectopic maxillary permanent canines (Figure 11) predisposed toward frank impactions. Maxillary expansion was initiated as a “first step” in the overall treatment of this patient. Approximately 6-months later, although obscured by the appliance itself in the radiograph, the maxillary canines have markedly improved in their position (Figure 12). A later panoramic radiograph shows the maxillary canines in relatively normal eruptive positions, and indeed, these teeth have subsequently erupted into the mouth uneventfully (Figure 13).

Case 2
The patient is a 12-year-old girl with a Class I malocclusion (Figure 14). The panoramic radiograph displays the right and left maxillary permanent canines with notable mesial axial inclinations (Figure 15). Maxillary expansion was initiated, and the maxillary primary canines and maxillary primary first molars were removed to provide space for the distal movement of the maxillary canines. A “2 x 4” appliance was placed, and the roots of the maxillary lateral incisors were now subject to positive changes in their axial inclinations and potential “guidance” of the maxillary canines (Figure 16). Figure 17 shows the maxillary canines in excellent eruptive positions. Figure 18 shows the maxillary canines erupted, bonded with attachments, and aligned.



Summary and conclusions

The pediatric dentist and orthodontist have an opportunity to identify ectopic maxillary canines that might lead to frank impactions requiring adjunctive surgical procedures. Early detection and assessment of maxillary canine ectopia can, in many instances, provide the basis for reducing the number of frankly impacted teeth for individual patients. Current research and empirically derived orthodontic clinical protocols firmly support the supposition that active intervention can make a measurable difference in a pediatric dental and orthodontic practice with respect to redirecting ectopically developing maxillary canines into normal osseous pre-eruptive positions. Increased interaction between the pediatric dentist or general dentist who chooses to treat patients in his/her practice, and the orthodontist is an essential element of such proactive dental developmental guidance and interception of potential maxillary canine impactions.

Bios

Elliott M. Moskowitz, DDS, MSd, CDE, is a Clinical Professor in the Department of Orthodontics at New York University College of Dentistry. He is a Diplomate of the American Board of Orthodontics and Fellow of the American and International College of Dentists. He received his orthodontic training as well as an MS (in dentistry) from the New York University College of Dentistry. He is the former Editor of The New York State Dental Journal and serves on the editorial advisory board of numerous orthodontic publications, including Orthodontic Practice US. He also is the current President of the American Association of Dental Editors. Dr. Moskowitz is the Senior Partner of The East Side Orthodontic Group in Manhattan.

Ronniette C. Garcia, DDS, is a Clinical Assistant Professor in the Department of Orthodontics at the Columbia School of Dental Medicine and a Diplomate of the American Board of Orthodontics. She is a graduate of the Columbia School of Dental Medicine orthodontic residency program and is affiliated with the East Side Orthodontic Group in Manhattan.

M. Bina Park, DDS, MS, is a Diplomate of the American Board of Orthodontics and a partner of the East Side Orthodontic Group in Manhattan. She is a graduate of the University of Michigan postgraduate residency program, where she won the Sicher Award for Research.   

Eleni Michailidis, DDS, MS, MPH, is a graduate of the Columbia School of Dental Medicine Department of Orthodontics Postgraduate residency program and has earned both an MS and an MPH from the same institution. She is affiliated with the East Side Orthodontic Group in Manhattan.

References

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