Premature deciduous tooth loss: a rare case of detrimental sequelae to the permanent dentition

Premature deciduous tooth loss due to caries or trauma is prevalent among children, with extraction of decayed teeth being the most common reason for children aged 5–9 years in the UK to receive a general anaesthetic.¹ For both the referring general dental practitioner and receiving orthodontist, it is prudent to be aware of the potential for detrimental sequelae to the permanent dentition that may result because of this.

Early loss of deciduous molars and canines has been associated with an increased risk of centreline disturbance,² loss of space with ensuing risk of arch crowding, tooth displacement, impaction and ectopia.³ The second deciduous molar is regarded as the ‘key tooth’ in the primary dentition⁴ because its premature loss has been associated with a greater reduction in leeway space than the first deciduous molar, and is therefore considered to have a more significant impact on malocclusion in the permanent dentition when not managed adequately.^4,5,6

In cases of premature deciduous tooth loss, an orthodontic opinion should be sought, when appropriate, to manage and minimize the risk of potential detrimental effects.⁷

Case report

A 17-year-old male patient, AH, was referred by his general dental practitioner to the orthodontic department at a district hospital regarding his unerupted UR5, congenitally absent lower 5s and ‘short roots’ incidentally found on a peri-apical radiograph (Figure 1).

AH presented with the chief complaint of ‘spaced teeth’, and he wanted to ‘close the gaps, and straighten his teeth’. He was a regular dental attender, with a history of early loss of upper deciduous second molars due to caries.

On examination, his lateral profile view showed a mild skeletal II pattern with competent lips at rest and an increased lower face height. He had Class I incisors with an average overjet and overbite, and bilateral Class I buccal segments (Figure 2). There was severe crowding of the upper arch (14 mm) with some anterior midline spacing, and the lower arch showed mild spacing of 3 mm. His arches were otherwise well aligned. AH had congenitally absent lower 5s, a palatally positioned UL5 and an unerupted UR5. There was no mobility associated with the erupted upper premolars, and they were asymptomatic.

Intra-oral peri-apical radiographs and an orthopantogram were taken initially (Figure 1), which suggested possible root damage of the UL4 and UR4 associated with the impacted upper second premolars.

To accurately assess the root damage, a CBCT scan (Figure 3) was taken of the maxillary premolar regions, which revealed the following. UR5 was palatally impacted with a distal tilt, and its root length was measured at 11.5mm. UR4 had almost total palatal and approximately 50% buccal root resorption. The fully erupted and palatally positioned UL5 had a blunted root at the apex, with an 8.5-mm measured total root length. Its eruption path had caused almost complete obliteration of the palatal root of the UL4, and considerable resorption to the buccal root (Figure 3b).

AH was fully informed of the findings, and warned of the risk of loss or damage to the upper 4s and UL5 due to the root resorption. The following options were discussed regarding his ongoing management:

• Extract UL5 and UR5 only, with no orthodontic treatment;
• Extract UL5 and UR5 only, with fixed orthodontic appliances to align the arches;
• Extract UR4 and UL4 with closed exposure of UR5 and fixed orthodontic appliances, with a view to align the UR5 and UL5.

After an in-depth discussion of these options, AH decided on the third option to extract UR4 and UL4 with closed exposure of UR5 and fixed orthodontic appliances. Provided the UR5 aligned, this was deemed to have the best long-term prognosis for the patient's dentition owing to the significant resorption of both upper first premolars. AH was consented for the following treatment plan:

• Oral hygiene to an exemplary standard;
• Extraction of UR4, UL4, closed exposure and gold chain bonding of the UR5;
• Fit of transpalatal arch (TPA) on maxillary 6s to provide horizontal anchorage, preventing mesial drift and space loss until alignment of UR5 and UL5 was achieved
• Fixed appliances to align upper 5s, close the lower arch spacing, and retain Class I incisor and buccal segment relationships
• Finishing and retention.

AH commenced treatment with extraction of UR4 and UL4, and closed exposure with a gold chain on UR5. Orthodontic treatment began with a TPA on maxillary 6s 2 weeks after surgery to prevent mesial drift of the upper first molars until UR5 was aligned. An upper fixed appliance was also bonded (American Orthodontic mini master series, MBT prescription, GAC, USA) with 0.016″ nickel–titanium wire (Neosentalloy, GAC, USA) and a quick ligature on UL5 (Figure 4). He progressed to an 0.016″ nickel–titanium piggy-back wire placed in the gold chain to apply traction on the UR5 with an 0.016″ stainless steel archwire to hold arch form.

The UR5 was moved mesially using a closed power chain attached to the existing gold chain links with a stainless steel ligature, and connected from UR4 to UL4 to gain the necessary traction. Following eruption and mesial movement of UR5, an orthodontic button was placed with a distal power chain to the UR6 to begin to fully align and derotate the tooth into the arch (Figure 5). This provided good movement and repositioning of the tooth into the line of the arch.

After 15 months of treatment, a lower 0.016″ nickel–titanium fixed appliance (Neosentalloy, GAC) was bonded with a band around the LR6. Once progression had been made to posted 19/25 stainless steel wires in both arches, any residual spacing was closed using closing coils. All appliances were debonded with a final result of Class I incisors and almost perfect Class I buccal segments (Figure 6). The patient was delighted with the outcome, with minimal dentistry required in the long term.

AH presented with a treatment requirement owing to unfortunate and rare consequences of his premature deciduous molar loss. This was likely to have been associated with a reduction in maxillary arch length and subsequent impaction and displacement² of his UR5 and UL5. The average maxillary premolar root length is 13–14mm. On his initial CBCT imaging, the UR4 had approximately 6 mm of buccal and 2 mm of palatal root remaining, and UL4 had 4–6 mm of buccal and 2 mm of palatal root remaining. It was felt the root resorption of the UL4 and UR4 gave these teeth a poorer long-term prognosis than the displaced and impacted second premolars, thus warranting their extraction.

Discussion

This is a useful learning case for the orthodontist when encountering impacted 5s. Here, appropriate clinical assessment and investigation revealed the unfortunate consequence of AH's premature deciduous tooth loss, enabling its appropriate management. It demonstrates the use of orthodontics to correct the detrimental sequelae of early primary tooth loss, negating the need for placement of dental prostheses. AH completed his 2-year combined surgical and orthodontic treatment satisfied with the result, while keeping his long-term financial impact low.

From the author's critical perspective of treatment outcome, AH does not have a perfect interdigitated Class I buccal segment on the left side. We decided to accept this marginal discrepancy as his treatment was completed during the COVID-19 pandemic, when additional hospital appointments, for marginal health benefit, were not appropriate.

Conclusion

Early primary tooth loss can have long-term detrimental effects on a patient, and it is indicated that these patients have an increased orthodontic need.⁴ This case highlights what can occur if impacted teeth are left in situ without regular assessment or a long-term plan. While uncommon, AH's case shows the rare effect of upper second premolar impactions causing significant root resorption of the upper first premolars. Here, the detrimental sequelae led to significant costs for the patient and health service in terms of time and financial impact.

The case of AH demonstrates how to orthodontically correct the unwanted sequelae of early tooth loss, and highlights the importance of appropriate assessment and investigation of the orthodontic patient with impacted 5s following premature deciduous tooth loss.