Fall 2002 Presentation Summary:

"Understanding Impacted Teeth – Then Treating Them Successfully"

Presented by Dr. Adrian Becker, BDS, LDS, RCS, DDO, RCPS, on May 31, 2002, at the Southern Region Meeting.
Summarized by Dr. Hong B. Moon, Southern Region Editor

Dr. Becker began his lecture series focusing on the etiology, diagnosis and treatment planning of impacted teeth (Lecture 1).

Then he specifically presented the rationale for treating unerupted, dilacerated and severely traumatized incisor teeth and ways of dealing with severely displaced maxillary canines and other teeth (Lecture 2).

This lecture also covered teeth from within dentigerous cysts and teeth that resorb the roots of adjacent teeth (Lecture 3) as well as multiple impactions and cleidocranial dysplasia (Lecture 4).

Dr. Becker stressed the treatment of impacted teeth in the context of an overall orthodontic treatment strategy.

Lecture 1:

Accurate Positional Diagnosis – The Key to Success in Treating Impacted Teeth

Dr. Becker emphasized, “Without knowing exact location and orientation of the tooth, we can neither plan appropriate movements nor be certain of a successful outcome.”

Radiology

The aims of radiology in relation to impacted teeth are (1) to find the pathology such as supernumerary teeth, cystic damage, ankylosis, abnormality of crown or root, resorption of crown or root, and (2) to find the location using tube-shift method (lateral or vertical shift), panoramic view, views at right angles, and/or computed tomography.

The position of the apex of the tooth determines its prognosis, and this is not possible to mentally reconstruct from a pair of periapical films alone.

Surgical Exposure

The following principles for surgical exposure of impacted teeth were suggested: (1) wide soft tissue flap, (2) minimal exposure of the tooth – hemostasis and small attachment bonding, (3) cementoenamel junction undisturbed, (4) remainder of follicle undisturbed, and (5) full flap closure.

Dr. Becker favored closed surgical exposure over open surgical exposure.

In terms of a presurgical orthodontic treatment sequence, the clinician should align and level, reopen space, place maximum thickness archwire, and prepare any auxiliary springs.

At the surgery is the best opportunity to confirm the location, orientation, relation, and disimpaction strategy before placing attachment and applying traction.

Periodontal Concern

Dr. Becker frequently quoted, “…you can always tell which canine was the one that was previously impacted.”

Dr. Becker commented that this is certainly true when radical surgical exposures have been performed and when periodontal grafting has been employed to cover up its shortcomings.

He added, “If you have a good 3-D mental picture of the tooth and its relations, if the surgeon has treated the tissues conservatively and if the orthodontist has properly planned tooth movement, there is no periodontal condition to treat.”

Successful Outcome

Success in the treatment of an impacted tooth should not be measured merely by the fact that the tooth has reached its place in the dental arch. Success can only truly be claimed when tooth position, crown length, color, and periodontal condition make it indistinguishable from any other tooth.

Lecture 2:

The Rationale for Treating Unerupted, Dilacerated and Severely Traumatized Incisor Teeth

Dr. Becker continued to cover some controversial issues of the impacted teeth. (e.g., Treat or not to treat? Extraction vs. non-extraction?)

Rehabilitation Alternatives

If the prognosis is poor, the extraction option is viable. Even if there might be serious deficiency of surrounding tissue after extraction, several rehabilitation alternatives can be still considered, such as: removable denture, resin-bonded bridge, conventional bridge, implant or orthodontic substitution. Each has the following advantages and disadvantages:

• Removable denture – hides bony defect, but maintains space poorly, accumulates plaque, becomes ill-fitting quickly and gives poor retention
  
  
• Resin-bonded bridge – the bony defect is un- disguised, poor reliability of bonding
  
  
• Conventional fixed bridge – tooth material destruction, potential pulp damage, bony defect undisguised, and gingival margin exposure
  
  
• Implant – not in growing patient, when the bony ridge is inadequate
  
  
• Orthodontic substitution – can reduce bony defect but may produce many esthetic problems including midline deviations, asymmetry of width/height/form, poor gingival architecture.

Movement of Impacted Tooth: Rationale

If the impacted incisor is extracted, expect a loss of alveolar bone during the procedure and subsequently by resorption.

After healing, ridge becomes thinner (buccal-lingual) and more deficient (vertical). Space reopening and prosthetic replacement is still needed.

These disadvantages favor orthodontic correction of the impacted tooth for most cases since eruption of the natural tooth corrects the bony deficiency, maintains symmetry, delays prosthetics, provides natural space maintainer and natural appearance.

If the impacted tooth has experienced trauma, it may erupt normally, while some don’t erupt but are retrievable and potentially useful.

In cases of atypical root development where the root is dilacerated or arrested, the crown may be displaced far from its normal place. Nevertheless, the tooth usually has a normal PDL and its response to orthodontic force is normal.

Furthermore, the crown anatomy of the affected tooth may have normal size, form, color, and it is supported by its own root (better than anything the dentist can make!).

Treatment Timing

Onset of treatment should be timed to the stage of development of the tooth, ideally two-thirds of the final expected root length. If it is difficult to assess the root development, use the contralateral tooth as a guide.

Lecture 3:

Rescuing Teeth from Dentigerous Cysts

Dentigerous Cyst

A dentigerous cyst is a cyst surrounding the completed crown that expands at expense of surrounding bone and displaces affected and adjacent teeth.

The etiology of the dentigerous cyst is unknown, but it is associated with chronic local infection (e.g. granuloma), root canal treatment in deciduous tooth, and proximity of lateral incisor root (e.g. impacted canine).

Some questions remain about treatment goals. Can we bring them into the dental arch? Can we bring periodontium and bone with them? Can we make them indistinguishable from any other teeth?

Treatment of Teeth in Dentigerous Cyst

Steps for conservative treatment of teeth within a dentigerous cyst are as follows:

• Surgery (marsupialization)
  
  
• Wait for bony fill-in (with x-ray follow-up)
  
  
• Orthodontic set-up leveling, alignment, and preparation of anchorage unit
  
  
• Surgery to expose teeth and bond eyelets
  
  
• Traction to archwire (rotation and uprighting)
  
  
• Controlled root movement with standard brackets
  
  
• Delay exposure and attachment of traction until bone fill-in has occurred

The process of exposing uprighting and positioning teeth is a challenge, but the benefits of building new alveolar bone and natural appearance and function is substantial.

Lecture 4:

Multiple Impactions

Cleidocranial Dysplasia

The general characteristics of Cleidocranial Dysplasia are: Autosomal dominant, many sporadic cases, both males and females affected, no mental retardation, late physical development, incomplete/missing clavicles, open fontanelles, and short stature.

The common characteristics of dental disability in Cleidocranial Dysplasia are: Class III skeletal pattern, reduced lower facial height, delayed dental development, poor alveolar height, over-retained deciduous teeth, unerupted permanent teeth, lessened eruptive force and multiple supernumerary teeth.

Treatment of Multiple Impacted Teeth

The guiding principle regarding treatment timing is that teeth normally erupt when one-half to three-quarters of the root has developed.

In sequence of dental age, first molars erupt spontaneously, incisors erupt at age seven to eight, premolars/canines erupt at age ten to eleven, and second molars erupt spontaneously.

Treatment starts with incisors first: vertical correction-erupting tooth using adjacent erupted teeth and/or vertical elastics and horizontal correction-aligning teeth.

Next treatment goes with premolars and canines. Sources of anchorage are adjacent erupted teeth and vertical elastics.

The Role of the Surgeon

Lastly, Dr. Becker emphasized the surgeon’s role for overall success, especially for the treatment of impacted teeth.

The surgeon should extract deciduous and/or supernumerary teeth, expose the impacted teeth, provide access for attachment bonding, conserve bone, achieve full closure for primary healing, and permit immediate traction for the orthodontist.

Dr. Becker showed many clinical cases to discuss the diagnosis and treatment of impacted teeth. This lecture gave the practicing orthodontist a focused appreciation of the spectrum of impacted teeth. Dr. Becker’s lecture was very well received among the audience.

For further information, you may consult Dr. Becker’s textbook The Orthodontic Treatment of Impacted Teeth (Thieme’s Publications), or a summary article in the June, 2002 AJO/DO: “Early Treatment for Impacted Maxillary Incisors.”

(PDF version)*