We encountered a case of localized periodontitis (stage III, grade B) during orthodontic treatment. The current case presents two significant considerations for clinicians. First, localized stage III periodontitis, which may be missed during initial examination, can become exacerbated during orthodontic treatment. Exacerbation may require temporary interruption of orthodontic treatment to allow resolution of active periodontitis through periodontal intervention. Second, patients who have undergone periodontal treatment should be carefully examined by a periodontist during orthodontic treatment. Orthodontists should monitor the periodontal tissue carefully during orthodontic treatment and collaborate with periodontists as and when necessary.
Pre-orthodontic oral examination is often performed by general dentists, and not all cases are evaluated by periodontists using periapical radiographs (the Dental X-P 10 or 14 card method) to thoroughly assess the bone levels. Panoramic radiography and basic periodontal examination before proceeding with orthodontic treatment are probably more common if the patient has no relevant complaints. However, as it is uncommon for a dentist to have expertise in both orthodontics and periodontics, localized periodontitis that may not require periodontal surgery, such as in this case, may be overlooked before orthodontic treatment.
Fixed orthodontic treatment has minimal to no significant effects on the clinical attachment levels (periodontal conditions) in healthy adults and adolescents [9, 10]. However, in cases of localized moderate periodontitis with no obvious symptoms, as in the present case, orthodontic treatment may induce acute symptoms and bone resorption. If periodontal inflammation is not controlled during orthodontic treatment, periodontal damage can progress rapidly, leading to additional attachment loss . In the worst-case scenario, the orthodontic treatment may have to be interrupted. However, it is possible to recover from such a situation with accurate diagnosis and professional treatment.
We performed a thorough clinical and radiographic evaluation of individual teeth in addition to bacteriological examination of the sites with deep periodontal pockets. The World Workshop in Periodontology (1999) defined aggressive periodontitis as “a type of periodontitis that typically affects young people with a non-contributory medical history and familial aggregation, resulting in rapid attachment loss and bone resorption” . According to the consensus report from the International Workshop on the Classification of Periodontal Diseases and Conditions, an increase in the prevalence of Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans in some populations is a potential secondary feature of localized and generalized aggressive periodontitis . As some periodontal bacteria with high pathogenicity contribute to the development of aggressive periodontitis  and affect its prognosis, we performed bacteriological examination. Treponema denticola has been increasingly detected in patients with aggressive periodontitis , and according to the 1999 American Association of Periodontology classification of periodontitis , continued supportive periodontal therapy after orthodontic treatment is necessary to prevent recurrence of periodontal disease.
In the present case, we aimed to complete periodontal treatment and resume orthodontic treatment as soon as possible. We administered systemic antibiotic therapy along with FMD to effectively treat severe generalized periodontitis within a short period . We selected FMD for the following reasons: (a) real-time polymerase chain reaction showed that the counts of periodontitis-related pathogenic bacteria in the maxillary left second molar area, mandibular right second molar area, and saliva were > ten times higher than the reference value; (b) to minimize the risk of reinfection from the SRP-treated sites to untreated sites; (c) to achieve timely completion of periodontal treatment and to resume orthodontic treatment as soon as possible; and (d) to prevent or minimize bacteremia and a rise in body temperature, which are possible adverse complications of FMD [15, 16]. To achieve these objectives, periodontal disease elimination therapy was performed at sites with PPD ≥ 4 mm, which were confined to the molars. In accordance with the original protocol, FMD was completed within 24 hours [2, 15, 17]. Oral sitafloxacin, which is effective against periodontitis-related pathogenic bacteria, was administered as an adjunctive therapy .
FMD minimizes the risk of reinfection from untreated periodontal pockets. Its clinical effects have been extensively researched [4, 19,20,21]; however, the synergistic effect of antibiotic or chlorhexidine treatment with FMD is debatable. The combination of chlorhexidine treatment with FMD demonstrated clinical outcomes that are superior to those of SRP per quadrant in several trials [22,23,24]; in other trials, the effects of FMD with or without antiseptics are comparable to those of standard SRP [25,26,27]. The use of 0.2% and 1% chlorhexidine is banned in Japan, preventing its use in the present case. In Japan, as cases of anaphylactic shock due to chlorhexidine gluconate have been reported, the concentration of undiluted chlorhexidine gluconate is regulated up to 0.05%. In practice, chlorhexidine gluconate is often applied at a concentration of approximately 0.01% because it is diluted for use. When bacterial factors are suspected to be more strongly associated with periodontal disease than host or environmental factors, the treatment should include FMD and adjunctive antimicrobial therapy with a limited dosage and duration of treatment. Full-mouth SRP has severe systemic effects, such as fever and a transient increase in the inflammatory cytokine levels . The concomitant use of antimicrobial agents can significantly reduce bacteremia caused by SRP . The combined amoxicillin and metronidazole administration is the most frequently used antimicrobial treatment during FMD [29, 30]. An earlier meta-analysis reported that the use of a combination of amoxicillin and metronidazole as an adjuvant to SRP presented therapeutic effects . However, metronidazole is not indicated in Japan for infections in the oral cavity. Thus, in the present case, sitafloxacin was used, and we observed a significant post-treatment decrease in red-complex bacteria in active periodontal pockets [32, 33].
The risk of development of resistant strains due to the misuse of antimicrobial drugs must be recognized. To reduce the emergence of antibiotic-resistant strains and adverse effects, we chose a 7-day antibiotic regimen. In previous investigations on antibiotic resistance, researchers discovered that a single course of systemic antibiotics combined with mechanical debridement resulted in transitory bacterial resistance that dissipated shortly after the treatment was stopped [34, 35]. In the present study, the initial bacteriological examination had shown significant numbers of red and orange complexes. Therefore, we used sitafloxacin to eradicate these bacterial complexes and prevent bacteremia and febrile reactions, which are side effects of FMD. However, in cases where the bacterial levels are not significantly high, conventional SRP may be adequate.
Localized stage III periodontitis overlooked during screening of the patient can manifest with acute symptoms during orthodontic treatment. Our report presents two important clinical considerations in this regard. First, as orthodontic treatment often involves extraction procedures and treatment interruption is not possible in principle, orthodontists should consider a thorough periodontal diagnosis by the patient’s family dentist or a periodontist before orthodontic treatment, and general dentists should consider the possibility that their patients may be candidates for orthodontic treatment. Orthodontists should be informed on periodontitis; particularly, orthodontists treating adults must be knowledgeable regarding the management of localized severe periodontitis through interdisciplinary collaboration with periodontists. Second, if periodontitis or local acute inflammation occurs during orthodontic treatment, temporary interruption of treatment followed by diagnosis and treatment by a collaborating periodontist may facilitate recovery. In the present case, the periodontal parameters were improved, alveolar bone resorption stabilized following basic periodontal treatment with FMD and oral sitafloxacin, and the patient resumed orthodontic treatment. This case of localized periodontitis manifesting during orthodontic treatment may be rare; however, with the increase in the number of adults seeking orthodontic treatment, such cases are expected to be more common. In the future, it is desirable to establish clinical and bacteriological evaluation techniques that can be used by orthodontists, periodontists, and general dentists together.