Severe Impactions and the Orthodontic Ball Park
Published: May 2018
Bulletin #77 May 2018
Severe Impactions and the Orthodontic Ball Park
The relatively inexperienced young orthodontist’s diagnosis of an ”impacted tooth” might be labelled something more modestly and less scarily by a more senior colleague as a “tooth with delayed eruption”. It may have been the result of inadequate or lost space due to an early extraction, or perhaps due to a mildly deflected path of eruption. This tooth will frequently resolve merely with the provision of space and usually without surgery – always assuming that the practitioner is prepared to give it time. In the absence of a judicious “wait-and-see” policy, surgical exposure will inevitably be performed. Nevertheless, it is highly likely that this relatively trivial yet common level of anomaly represents a majority of the cases that make up investigative samples in the many studies of impacted teeth, on which wide-ranging operative conclusions are subsequently drawn. In the true spirit of the times, these trivial cases have been described by Dr. Chris Chang as “fake impactions”.1
Orthodontic appliances have been developed and perfected over the past century, honing in on what colleagues in our sister specialties consider us to be “the 5 degree-2millimeter profession”, because this is the degree of accuracy of which we are capable and which produces the million dollar smiles. Perhaps we should call this very special fine-tuning area of activity the “Orthodontic Ball Park”. We would have to define this as an area in which from the beginning of the appliance therapy, we are able to place brackets on all or most of the teeth, including the above-mentioned surgically-exposed impacted teeth and, at least partially, locking, ligating and/or tying-in a light continuous NiTi archwire. This is completely understandable and not denigrating my colleagues since, by and large, it is precisely what is required in the vast majority of orthodontic treatment plans, which achieve a high level of success and predictability. Indeed, the magnificence of the predictable outcomes that we are able to achieve provokes the envy of most other medical and dental specialist practitioners.
When a tooth is severely ectopic and way off the beaten track, it is often too distant in any of the three planes of space for it to be included in the overall unified appliance scheme. Its orientation may make it relatively inaccessible from the point of view of bracket placement. The situation deserves or perhaps dictates, a specific and focused strategy all to itself, most often unrelated to the overall malocclusion that concurrently needs to be treated. Because of its distance from the desired location in the dental arch or because of the amount of root movement that will be necessary to bring it to its place and into the “Orthodontic Ball Park”, such a tooth requires special consideration in relation to anchorage preparation, unusual attachments, customized traction springs and other gadgets. In these situations, great importance is attached to preliminary planning.
If other teeth are to be exploited as anchor units, it is essential to broaden the anchor base to include as many of the other teeth as possible sharing the load. Consolidation of the anchor base would require leveling and alignment in both arches, followed by the insertion of heavy slot-filling rectangular archwires. It cannot be overstated that inadequate anchorage preparation is the main cause of failure in the treatment of impacted teeth.2
Several months of treatment are needed to reach this stage, before the orthodontist may turn his/her attention to confronting the wayward tooth. While this full and composite dental anchor base may suffice for most, there are several instances where even this precaution is inadequate and the use of intermaxillary and extra-oral traction and a temporary anchorage device may be needed as supplements. This is true of the more extreme cases with single or multiple impacted teeth, where both distance from the site and a root torque demand discrepancy may be significant.
However, it is often preferable to use a well-placed TAD at
the outset and to separate the orthodontic treatment plan into two distinct and
separate dynamic systems which are only linked up together later on, when the
aberrant tooth has been brought to its place. This offers the opportunity for
streamlining the treatment and reducing its duration.
Fig. 1. Intra-oral views of the 14.9 year old male patient prior to treatment.
The illustrative case I describe here is of a 14.9 year old
male in the permanent dentition stage (Fig. 1). The skeletal base relation was mild
class II and, while the permanent molars were in class 1 relationship, the
dentition tended towards class II in the canine and incisor regions, with an
anterior overjet of 5mms, a deep overbite of 5-6mms and the lower incisors
impinging on the palatal gingivae. The maxillary incisors were mildly
over-erupted and retroclined, presenting an increased measure of gingival
display (gummy smile) while the mandibular incisors were proclined and
over-erupted in relation to the posterior teeth. The only erupted second
permanent molar in the mouth was seen on the right side of the mandible. 
Fig. 2. The initial panoramic view of the dentition showing the horizontally impacted left mandibular second molar and a 5 degree distal tip of the adjacent first molar.
The panoramic radiograph showed the presence of all permanent teeth, including third molars (Fig. 2). The root apices of all teeth were closed, with the exception of the third molars and possibly maxillary second molars, suggesting a dental age of 14-15 years, despite the non-eruption of the other 3 second molars. In the maxilla and despite their tardy eruption, it was considered that the second molars would eventually erupt unaided – delayed eruption. On the left side of the mandible, the second molar was strongly tipped mesially and lying horizontally at an angle of approximately 80 degrees to its normal axial orientation. It was impacted well down in the bone against the apical portion of the distal root of the first molar. It was seemingly responsible for the 5 degrees distal tip of that first molar. All four third molars were present in the early stages of root development, although the one on the left side of the mandible was located immediately above the second molar, in a piggy-back position.
The treatment plan involved treatment of the overall malocclusion in the conventional manner, with brackets and molar bands placed only on the teeth mesial to and including the first molar teeth. The left mandibular second molar was accorded separate and special treatment with a different attachment and a different system of force application.
The sequence of treatment was as follows:-
1. Placement of the fixed multibracketed appliances, which was performed in 2 separate stages, 4 weeks apart, involving one dental arch at a time, with the placement of NiTi aligning archwires.
2. Following the second post-bonding appointment, arrangements were made with the oral surgeon for the surgical procedure. Due to his heavy workload, this only took place 2 months later, during which time, the alignment and leveling phase was completed.
3. Surgery was performed by Prof. Nardy Caspi under general anesthetic cover as follows:-
a. In the mandible, the left third molar was extracted and the second molar exposed at its most superior aspect i.e. on the anatomical distal surface and in a closed surgical exposure procedure.
b. Because of the relatively large tooth surface presented and the critical assistance of the oral surgeon in preparing and maintaining complete isolation and hemostasis, I was able to bond two separate eyelets, using a gel etchant and light-cured composite bonding agent. The soft steel twisted ligatures that had been threaded through the eyelets ahead of time were drawn upward above the surgical area. Great care was exercised during the entire exposure procedure to avoid any possibility of simultaneous exposure and chemical contamination of the exposed bone and the roots of the adjacent first molar.
c. The surgical flaps were fully sutured back to their former place, leaving only the ends of the twisted wire ligatures visible in the mouth and turned over to act as hooks for future traction.
d. In the maxilla, the left third molar was extracted and the unerupted second molar exposed by an open surgical procedure, to permit its subsequent spontaneous eruption.
e. Surgical access was established through the mobile oral mucosa of the buccal vestibulum to the inferior surface of the zygomatic process of the maxilla. A second incision made parallel to the first, but in the attached gingiva. Communication between the two incisions was made by blunt dissection through the connective tissue under the intact mucosa between the two (Fig. 3).
Fig. 3. An intraoral view during surgery, showing the L-shaped surgical plate bolted with 3 screws to the inferior border of the zygomatic process. The approach was through a horizontal incision in the vestibular mucosa. Note the second incision was made through the attached gingiva, and a communication made by blunt dissection under the attached gingiva, through which the leg of the surgical plate was passed. A terminal bend has been made in the surgical plate for attaching the up-and-down elastics.
f. An L-shaped surgical plate was secured in the
zygomatic process using 3 screws. The other leg of the plate was taken through
the lower attached gingiva incision and its extremity turned over to act as a
hook for elastics. Had the hooked end been taken through the highly mobile vestibular
mucosa, it would have resulted in chronic tissue irritation, which was avoided
by this method. The surgical incisions were then sutured fully closed. 
Fig. 4. The post-surgical panoramic radiograph shows the sockets of the third molars and the attachments placed on the anatomical distal aspect of the crown of the second molar. It also shows the zygomatic plate (arrow) on the maxillary left side.
g. Surgical excision of the right maxillary and mandibular third molars was performed at the same operation (Fig. 4).
At a subsequent orthodontic visit, vertical up-and-down
elastic were placed by the patient between the zygomatic plate hook and the
hooked end of one or both the twisted steel ligature emanating from the
mandibular gingiva as soon as he could comfortably place them. 
Fig. 5. This panoramic view was taken when the
first buccal tube was place and the mandibular archwire could be extended to
engage the second molar. The tooth was now in the “Orthodontic Ball Park”. The zygomatic plate is arrowed.
The hooked ligature wires were removed and direct extrusive steel ligation was made between the eyelets and a distally extended fully engaged archwire on that side. Simultaneously, the location of the up-and-down elastics was transferred to the mandibular first molar bracket, to support the anchorage value of the mandibular teeth on that side.
Once a portion of the buccal aspect of the tooth became supragingival, an attachment could be placed in a much more convenient and efficacious location. Thus, the remainder of the uprighting movement of the second molar was achieved using the main archwire, by progressively bonding a single molar tube at ever reducing angles to the horizontal. This was accompanied by continuing with the up-and-down elastics as required.
Fig. 6. A panoramic view taken at the
completion of treatment, with a mandibular anterior bonded twistflex retainer
in place. Note the shortened roots of the two mandibular molars of the left
side, in comparison to those of their right side counterparts.
The appliances were removed from the teeth 18 months after their initial placement, with the exception of those on the 4 posterior teeth of the left side of the mandible, to permit minor correction for 4 more months (Figs. 6, 7).
References
1. Chris H Chang. Innovative impaction treatment. A lecture at the American Association of Orthodontics 2018 Annual Session, Washington D.C.
2. Becker A, Chaushu G, Chaushu A. An analysis of failure in the treatment of impacted maxillary canines. American Journal of Orthodontics & Dentofacial Orthopedics 2010;137:743-54.
