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| Panoramic radiograph shows a well-defined unilocular radiolucency associated with impacted crowns #27,28. |
IIn instances where impacted teeth have not erupted it may or may not be evident clinically at the time the patient is evaluated, however it should be a consideration and at this point it’s important to advise the parents of this possibility and confirm with you imaging studies. When the apices of teeth have a close proximity to the inferior border of the mandible and when they remain in this position, especially in comparison to the adjacent erupted or erupting teeth they need orthodontic forces to erupt, these teeth are likely ankylosed.
Recall tooth eruption requires resorption of bone in a three-dimensional pattern to allow the tooth to move. Ankylosis is a physiologic process of replacement resorption, that requires erroneous replacement of cementum and dentin with bone within the periodontal ligament space, eradicating the periodontal ligament space (PDL). This is an inflammatory mediated process that may follow trauma or infection within proximity to the apex of the tooth. Toddlers tend to be clumsy and it’s not uncommon for them to be involved with a fall or a hit to the inferior border of the mandible which can damage the developing tooth bud and its associated (PDL).
Deciduous mandibular molars are more prone to be ankylosed versus permanent teeth and mandibular molars are the most common permanent teeth to be ankylosed. This is most likely due to trauma to the inferior mandibular border at a young age. Some studies show that there is a higher incidence in Caucasians and Hispanics vs blacks and Asians. When patients present with this diagnosis it is important to act and treat this problem asap because as the patient ages and grows out of their teens, successful replacement of this tooth can be challenging.
ANKYLOSIS DIAGNOSIS
1. Infraocclusion
2. Vertically atrophic alveolar ridge
3. Diffuse irregular or the lack of PDL space and lamina dura
4. CBCT
5. Rule out adjacent structures and teeth that may be blocking eruption
6. Percussion tests are unreliable when <20% of the root surface is ankylosed to produce a positive test. 1
TREATMENT OPTIONS
When during a growth spurt, this may work to the patients’ advantage to treat the problem. During active growth, orthodontic assisted eruption can be considered but may not be affective.
1. Assisted orthodontic eruption after surgical exposure and removal of boney undercuts
2. Coronectomy and guided bone regeneration as needed
3. Corticotomy and distraction osteogenesis, is more successful with single rooted teeth.
ASSISTED ORTHODONTIC ERUPTION
First, it is essential to ensure that there are no teeth or other structures, a neoplasm, blocking or preventing eruption of the tooth.
Next, it’s important to ensure that the tooth has no remaining attachment to the bone which means during surgically assisted eruption, the tooth requires luxation/elevation within the PDL. Luxation of the root should be accomplished using a small slow steady force that will not damage or fracture the ankylosed section. Mobilization of the ankylosed tooth must be done cautiously and conservatively moving around the tooth from all angles. During luxation of the tooth, it’s essential to note the amount of force needed to mobilize the tooth as this may give an indication if the tooth will erupt.
CASE REPORT 1
• This is a 16 yr. 9-month Asian male referred for exposure and bracket of #27, #28. When the patient presented there was purulence evident interdentally on #29. Panoramic radiograph shows a well-defined unilocular radiolucency associated with impacted crowns #27,28. Of note is the appearance of the apex of #27 on the inferior mandibular border. The purulence was cultured and at the time it was recommended to his mother the lesion be biopsied and a CBCT (Cone beam computerized axial tomography) obtained as opposed to medical grade CT scan which is 10x’s the radiation of a CBCT. The patients mother declined the CBCT and made an appointment to return.
• 6 months later with a medical grade CT (Computerized axial tomography) in hand, the child was 17 y/o and had been under orthodontic care with active tooth aligners for a few months. At this point the crown of #27 was through the lingual cortex and causing blanching of the alveolar tissues. I explained to the mother that the window of opportunity to see forced eruption of #27 with surgical exposure is most likely gone however the mother wanted us to try.
• 3 months later the patient returns for biopsy and surgical exposure and bracketing of orthodontic appliances to erupt the teeth. Under moderate sedation a bite block and throat pack were placed and after local anesthesia a full thickness mucoperiosteal flap was created on the lingual aspect of the mandible to expose the teeth and the boney defect from the lesion was encountered and a negative aspiration test revealed it was not a vascular lesion. The crowns of teeth #27 and #28 were identified and boney obstructions over the heights of contour of the crowns were removed with hand instruments and a 557 bur. Using a controlled force, tooth #28 was easily elevated and #27 was significantly less mobile and it was felt during luxation to be firmly attached to the mandible inferiorly. The soft tissue encountered with in the mandible was a thinly lined cystic lesion that was easily curetted and the specimen was sent for histopathologic review, and came back as an odontogenic cyst. Both teeth had orthodontic appliances applied and ligated to the arch wire and the site curetted, irrigated and suturedclosed. The patient tolerated the procedure well and the mandibular defect is expected to restore the boney architecture with this four-wall defect with maximum osteogenic potential especially in this young patient.
• The patient was lost to follow-up, 2 yr. 2 months after the last visit the patient presented for re-evaluation of nonerupted #27. Tooth #28 fully erupted and the mandibular defect from the original lesion had resolved.
• Coronectomy of #27 was the treatment recommendation of choice followed versus no treatment. In addition, his wisdom teeth were also horizontally impacted causing symptoms from infection and extraction was recommended. Again, the patient was lost to follow-up.
Long protracted treatment requires a compliant patient for success. It’s essential that parents understand that this is a commitment that must be unwavering. Cases such as this individual may have had a different outcome had the patient returned in a timely manner. It is one of the most important aspects of this kind of treatment. Non-compliance is a deal breaker in these types of treatment cases and a point that must be made crystal clear to the parent and teen patients, who may have some input into ensuring they show up for treatment because if their parents don’t understand the urgency, maybe the minor child patient will.
CASE REPORT 2
• 15 y/o girl Referred for extraction #C, #H and exposure #11 and evaluation #19. Pat has had surgical exposure and bracket #19 twice unsuccessfully. Of note is the ninety-degree dilaceration of the roots on the inferior border.
• The patient and her mother’s primary focus was on extraction of her over-retained primary teeth and exposure of #11. They were very squeamish about discussing and addressing treatment options for tooth #19. It was my feeling that the patient and her mother were avoiding this due to fear and past experiences. For this reason, I spent extra time explaining the importance of addressing this site as it can be the tower of babel that topples if this is left untreated or treatment delayed further. We can see that the position of this #19 can in time create periodontal issues that can jeopardize #18 and #20.
• Under nitrous oxide and local anesthesia teeth #C & #H were extracted and #11 was surgically exposed and a bracket bonded to the crown.
• 1 year after initial visit, age 16 y/o, the patient was having pain and swelling associated with #19. Purulent drainage was cultured and the patient placed on penicillin. Coronectomy #19 and Guided bone regenerations (GBR)19 with intravenous sedation was recommended. Again, I explained the risks of treatment versus no treatment such as; chronic bone infection, fractured mandible, loss of adjacent teeth and additional problems. Also, I explained that patient has her youth on her side now for healing.
• The patient and her mom agreed to have nitrous oxide with local anesthesia for extraction of over-retained #J and #T. The patient tolerated the procedure well and the pericoronitis with #19 resolved, the patient was lost to follow-up.
Teeth that present with their apices at the inferior border of the mandible especially when they are dilacerated are highly suspicious for ankylosis especially when the remaining mandibular permanent teeth are above this plane. If their roots are formed and the patient is past their teens, the likelihood of eruption is remote. This means, children that are delayed or missing teeth just based on their age, and are in their pre-adolescent years should be screened for the possibility for neoplasm, ankylosis or congenitally missing. In the situation where the first molar is missing then this should be addressed at around age 6 years old, average eruption age. Of course, we have to consider for the rest of their dentition and compare maxilla to mandible and right to left.
Not all patients’ bodies read the anatomy books.
The Girldoc😉
1. https://pubmed.ncbi.nlm.nih.gov/6438004/
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