A 3.5-year follow-up of an unusual case of rampant caries during clear aligner treatment
Data publikacji: 12 cze 2023
Zakres stron: 171 - 182
Otrzymano: 01 sty 2023
Przyjęty: 01 kwi 2023
DOI: https://doi.org/10.2478/aoj-2023-0017
Słowa kluczowe
© 2023 Gengru Wang et al., published by Sciendo
This work is licensed under the Creative Commons Attribution 4.0 International License.
Dental caries, which manifests initially as white spot lesions (WSL) on enamel, is a relatively common complication of orthodontic treatment. Traditional fixed orthodontic appliances can promote bacterial plaque accumulation, limit patients’ ability to clean their teeth, and contribute to the development of caries.1,2
Clear aligner orthodontic technology has been evolving rapidly since its introduction 1998. Patients are able to remove the clear aligners at any time, which theoretically allows the practice of adequate oral hygiene. However, patients must wear their aligners for 20 to 22 hours daily to achieve optimal results and if oral hygiene is inadequate, bacterial plaque will remain between the tooth surface and the clear aligner leading to an increased risk of dental caries.3 Rampant caries is an advanced and severe form that affects multiple teeth.
Due to poor oral hygiene during clear aligner orthodontic treatment, the present case report presents an unusual manifestation of rampant caries and enamel demineralisation in an adolescent. Management options are discussed.
A 13-year-old Chinese female visited a hospital clinic in June 2017, with the chief complaint of severe tooth defects but no noticeable pain. She was unaware of the severity of her tooth-decay problem and was referred to the endodontic department to manage the main complaint related to the tooth defects. The endodontic department performed both the endodontic and restorative treatment, after which the patient started clear aligner orthodontic treatment in another hospital.
The patient was healthy with no contributory systemic disease. There were no abnormalities detected in tooth structure of her parents’ teeth. In addition, there was no history of similar problems in her maternal nor paternal ancestors.
In May 2016, the patient consulted a further hospital, complaining of “misaligned teeth”. Digital photos of the face and teeth, panoramic and lateral cephalometric radiographs, were collected (Figures 1, 2). It was noted that she had a deep overbite, an increased overjet and crowding of the anterior teeth. Mild gingivitis and small WSLs were observed at scattered locations, while pit and fissure sealants and fillings were noted in some teeth. No obvious dental caries was detected prior to orthodontic treatment. After an assessment, the patient was treated using clear aligner orthodontic therapy and was instructed to wear the aligners for 20 to 22 hr daily. The first and second aligners sets were to be worn for 14 days, while the remainder for 10 days.
Figure 1.
Digital photos of the face and teeth before clear aligner treatment.
Figure 2.
Panoramic and lateral cephalometric radiographs before clear aligner treatment.
The patient was asked to return to the hospital for review after one month, three months and six months. However, the patient did not attend until January 2017, which was six months after the last visit. Digital photos of the face and teeth (Figure 3) were retaken and revealed poor oral hygiene and extensive enamel WSLs. Oral hygiene was inadequate and hygiene education was re-emphasised. The treating clinician applied fluoride agents and the patient was asked to regularly return every month. However, the patient failed to follow the clinical instructions.
Figure 3.
Six-month follow-up after clear aligner commencement.
In June 2017, the patient returned to the clinic for a one-year check-up. The intra-oral photos (Figure 4) showed that a significant amount of tooth structure had been lost over the previous period. The tooth 46 crown had completely broken down. The patient and her parents became anxious about her teeth and consulted multiple clinics, but treatment continuation was declined. At the end of June 2017, the patient presented to the current hospital for an assessment.
Figure 4.
One-year follow-up after clear aligner commencement.
The patient visited the endodontic department at the present hospital for her main complaint of tooth defects on June 30, 2017. The patient said that she wore the aligners almost full-time last year. She frequently consumed sweet snacks rather than eat three main meals. The patient wore the aligners while eating and did not rinse her mouth nor the aligners afterward. She brushed her teeth occasionally but without flossing. Her oral hygiene was very poor and the teeth were still not aligned. Food debris and a heavy accumulation of plaque were found on all teeth and the clear aligners. Generalised mild gingivitis was present, with a white pseudomembrane noted on the gingivae. There were protruding composite resin aligner accessories on the labial surfaces of most teeth. All enamel was chalky white, fragile, and rough, while approximately 1/4 to 1/2 of the incisal enamel was lost on most teeth. Interestingly, the exposed dentine presented a mamelon-like shape even though the enamel was lost on the lower incisors (Figure 5). The dentine caries affecting most teeth was very soft. Secondary dental caries was observed around previous restorations on teeth 16 and 36. Tooth 46 had only root pieces with gutta-percha obvious in the root canals (Figure 6).
Figure 5.
One-year follow-up after clear aligner commencement, 1/4 to 1/2 incisal enamel has been lost on most teeth. Exposed dentine maintained its saw-like lobe shape in the four lower incisors.
Figure 6.
One-year follow-up after clear aligner therapy.
The vitality of all teeth except tooth 46 was tested with refrigerant spray and an electrical pulp test, and all responded within normal limits and without obvious pain. The teeth were not tender to percussion and responded with a vital sound. Tooth mobility was within normal limits while periodontal probing depth was consistently 3 mm or less, but bleeding on probing was detected at almost all marginal gingivae.
Panoramic periapical radiographs revealed extensive loss of tooth structure at the incisal edges (Figure 7).
Figure 7.
Panoramic radiographs after one-year clear aligner treatment.
To assess salivary function, unstimulated and stimulated salivary flow rates were measured, as well as saliva acidity. The patient was asked not to eat nor drink for one hour prior to the assessment. Her unstimulated and stimulated saliva flow rates were 0.35 ml/min and 1.9 ml/min, respectively, and within the normal range. The salivary pH was 6.8, which was also within normal limits (pH 6.6 to 7.1).
The patient had rampant caries, secondary dental caries, WSLs, generalised gingivitis and a malocclusion. Poor oral hygiene was identified as the main aetiology of caries and gingivitis, while the clear aligners were considered as a contributing factor.
The patient did not wish to continue her orthodontic treatment and only wanted her tooth defects repaired to extend the life of her dentition. The management options were explained to the patient and her parents, and the agreed treatment objective was to promote her oral health, mastication, and aesthetics considering the patient’s young age and preferences. The treatment was divided into three phases.
The initial phase of treatment was to improve oral hygiene, relieve symptoms, and arrest the progression of the rampant caries. Orthodontic treatment was first discontinued. A personalised oral-health education program was provided for the patient, who was advised to brush her teeth at least twice daily with a fluoride toothpaste and rinse her mouth immediately after eating. The parents were asked not to offer further snacks. The professional applications of fluoride agents (50 mg/ml NaF:22600 ppm, Duraphat) were applied after plaque removal by gentle brushing by the dentist. Ten percent CPP-ACP (GC Tooth Mousse) was recommended for daily use before bedtime.
During the second management phase, the dental defects were repaired. The dentine decay was gently removed, but some softened dentine close to the pulp was preserved to maintain pulp vitality. Direct composite resin restorations were placed on these teeth except tooth 31, which received pulp capping with bioceramics (iRoot BP, BioCeramix Inc., Vancouver, BC, Canada) (Figures 8, 9). Chalky demineralised enamel without apparent defects was treated with infiltrative resins (Icon, DMG Chemisch-Pharma zeutische Fabrik GmbH, Hamburg) (Figures 10, 11) whose therapeutic purpose was to establish mechanical stabilisation of the hydroxyapatite structure within the WSLs cavitation. When the patient presented to the hospital, the tooth 46 had no crown and gutta-percha was visible in the root canals. Four options were offered to manage the molar, which were: ① extract tooth 46, and replace with a removable denture; ② extract tooth 46, and maintain the space using a removable denture until future implant restoration; ③ extract tooth 46, and move teeth 47 and 48 forward to close the space; ④ retain tooth 46 temporarily if it is asymptomatic, but remove if swelling and pain occur in the future. The patient chose option ④ because of her young age. Considering tooth 46 was without symptoms at the time, glass ionomer cement was used to build up the crown for maintenance of the space.
Figure 8.
Treatment of the caries. Restorations on the lower anterior teeth.
Figure 9.
Treatment of the caries. Restorations for the cusp caries.
Figure 10.
Treatment of the caries. Infiltrative resins for enamel demineralisation of the posterior teeth.
Figure 11.
Treatment of the caries. Infiltrative resins for enamel demineralisation of the anterior teeth.
The patient completed the second phase of treatment in September 2017. Oral hygiene improved significantly and most of the symptoms were relieved. The patient was temporarily free of discomfort and decay.
The third management phase was supportive dental therapy and follow-up. The patient returned to the clinic in December 2017 for a three-month follow- up after caries management (Figure 12). The resin restoration on tooth 31 had been lost. Root canal therapy was performed in tooth 26 and teeth 26 and 36 were restored using composite resin. The other review appointments were completed by teledentistry, with no discomfort reported.
Figure 12.
Three-month follow-up after caries management.
The latest (3.5-year) follow-up was in December 2020 (Figure 13). The glass ionomer restoration of tooth 46 had been lost. Oral hygiene practice had deteriorated but significantly improved compared to the first visit. Plaque and debris were found on the labial surface of all teeth. The colour and shape of the gingivae generally appeared normal. All composite resin restorations were intact except the tooth 11 incisal margin. No new dental caries was identified and no other abnormalities were detected on visual or tactile examination. Tooth 46 was restored with a composite post, core, and a provisional polycarbonate crown, for better retention (Figure 14).
Figure 13.
3.5-year follow-up after caries management.
Figure 14.
Tooth 46 was restored with a composite post-core and a polycarbonate provisional crown.
The patient and her parents were satisfied with the provisional treatment and final result. The patient did not wish to restart orthodontic treatment. Continuing oral hygiene was emphasised, and a long-term follow- up was established for further management.
Dental caries is a common complication of traditional fixed orthodontic treatment. The initial sign of dental caries is WSLs, defined as the demineralisation of the enamel surface and subsurface without cavitation. The oral health of patients with traditional fixed appliances has always been a debated topic and extensively studied.2,4,5 Fixed orthodontic appliances make oral hygiene more difficult, limit the patient’s ability to clean their teeth and compromise naturally occurring self-cleansing mechanisms, resulting in increased plaque accumulation.6
In recent decades, increasing numbers of patients have accepted orthodontic treatment using clear aligners as a more aesthetic and comfortable alternative. Unlike fixed appliances, clear aligners are removable and therefore enable patients to practice oral hygiene under ideal circumstances. Patients can remove clear aligners to allow a thorough cleaning of all tooth surfaces, floss, interdental brushes, oral irrigation and by any other method. There are claims that clear aligners are more hygienic and cause less plaque accumulation on tooth surfaces.7’9
Information regarding enamel WSLs or caries formation in patients treated using clear aligners has not been widely disseminated. Few studies have investigated the incidence of WSLs during clear aligner treatment and the current clinical evidence is still insufficient to prove a substantive clinical relationship. Past literature4,7,10 has reported a lower incidence of WSLs during clear aligner therapy when compared with fixed orthodontic appliances. Furthermore, it has been suggested that patients treated using clear aligners have a lower risk of developing WSLs than those with traditional braces, which could be partially explained by a shorter treatment duration, patient education, motivation, or better pre-treatment oral hygiene.3,4,11,12 However, larger lesions with less mineral loss have been found during clear aligner treatment rather than in traditional fixed treatment.7
The presence of aligners could limit the flow of saliva, negate saliva washing, natural cleaning and buffering capacity7 and therefore interfere with the usual tooth cleansing activities of the lips, cheeks, and tongue. This would further facilitate the entrapment and development of plaque under the trays.
However, perhaps because of the close adaptation of the aligners to the teeth, a capillary effect is created, which causes fluids to be drawn into their interior space, and provides the opportunity for the pooling of liquids. The capillary effect could also create a conducive environment for bacterial growth and the aggravation of tooth demineralisation. In particular, if these liquids are acidic or sweet and remain near the teeth for a long time, significant decalcification and caries will occur.
A compromise in oral hygiene control, will likely lead to more plaque accumulation and an increased incidence and extension of WSLs leading to severe caries.13–15 It may be hypothesised that when oral hygiene is not consistently adequate and/or enamel mineral interchange is poor, clear aligners may be a worse option than fixed appliances.
Rampant caries can progress rapidly over a short time, which leads to a sizeable irreversible loss of tooth structure. It occurs most frequently in pits, fissures, and smooth labial surfaces of the teeth, particularly along the gingival margin, whereas the incisal edge and cusp are rarely involved. The present report showed a rare presentation of rampant caries. The patient had WSLs without defects on the labial surfaces of some teeth before orthodontics. One year later, the enamel of all teeth had chalky and soft demineralisation. However, the incisal edges and cusps of teeth, and not the labial surfaces, showed the most severe caries. About 1/4-1/2 of the incisal enamel was lost in the upper and lower incisors. The exposed dentine was moist and soft, showing the saw-shaped development lobes in the lower incisors. This may be explained by the fact that recessed and sheltered areas of the clear aligner (such as the cusp tips and attachment dimples) harbour more plaque than their flat surfaces.16
This unusual presentation of caries is likely due to the dissolution and detachment of hydroxyapatite and remaining dentine collagen fibrils, which is a scaffold comprising 30% by volume of dentine. Hydroxyapatite is the main component of dental hard tissue which can be dissolved in acid produced by oral bacteria. It accounts for approximately 86% of enamel volume and 50% of dentine. Usually, the exposed dentine fibrils wear down by occlusal impact. However, the patient did not remove her aligners during eating, therefore preventing dentine collagen fibril collapse and preserving an integrated framework of dentine.
Secondary dental caries was noted around previous fillings in teeth 16 and 36. The crown of tooth 46, which had a complete crown contour with a large restoration on the occlusal surface, broke down to root level over only one year, which highlighted the speed of destruction. It was hypothesised that there was a gradual accumulation of bacterial plaque in the microleakage of fillings which caused the rapid secondary caries. The rampant caries of the patient would have been easily controlled and avoidable if oral hygiene was optimal, bad dietary habits were corrected, or the early WSLs were detected and accordingly treated.
Rampant caries is a challenging dental disease. Clinicians are advised pay attention to early caries (such as WSLs) in clear aligner orthodontic patients, be mindful of risk factors, and have substantial control of caries. The prevention, diagnosis, and treatment of WSLs are crucial to minimising caries and tooth discoloration, which could compromise smile aesthetics. At the first sign of early enamel demineralisation, the clinician should have comprehensively analysed the reasons and proposed solutions immediately. However, current knowledge suggests that there is no agreed treatment protocol for caries associated with clear aligner wear. The clinician should consider the following options:
Dietary and oral habits should be recorded before the clear aligner therapy. Oral hygiene education should be provided throughout the entire orthodontic course of care, even after the completion of treatment. It is the responsibility of the clinician to minimise the risk of the patient suffering decalcification by educating and motivating the patients for excellence in oral hygiene practice. Regular recalls and personalised oral hygiene instruction are essential. The patients should be taught how to clean their teeth thoroughly utilising, toothbrushing, flossing, interdental brushing, and oral irrigation.
Clear aligner treatment often needs composite tooth attachments (accessories). The bonding of attachments is similar to the bonding of orthodontic brackets and the clinician should strictly control the area and time of etching. Acid etching times not exceeding 15 sec are favourable.17,18 There is no need to etch the entire labial surface of the crowns that will receive attachments18,19 and resin attachments and tooth surfaces must be polished after bonding.
Studies have shown that dental plaque biofilm can form on the surface of clear aligners.20 These appliances can induce changes in the ecosystem of the oral cavity, which, in turn, increases susceptibility to caries. Therefore, clear aligners need to be thoroughly cleaned and disinfected after 12 hr of intraoral usage or at least within 24 hr of usage.21 Patients need to be instructed on appliance cleanliness. Clinicians suggest different cleaning alternatives,22,23 either by the use of physical methods (toothbrush and toothpaste, ultrasonic concussion, etc.) or chemical methods (effervescent tablets, mouthwash, sodium hypochlorite, chlorhexidine, etc.).
Fluorides decrease the development and progression of dental caries by three different mechanisms. Fluorides may inhibit the demineralisation of the enamel, increase remineralisation, and deter the bacterial enzyme production of acids. Prophylaxis and topical fluoride application should be implemented: high- fluoride toothpastes, fluoride mouthwashes, gels and varnishes during and after the orthodontic treatment, especially for patients at a high risk of caries.2,5,24–26 The professional application or prescription of fluorides for home use include gels and toothpastes (maximum 5000 ppm), mouthwashes (223 ppm), and varnishes (23,000 ppm). The daily use of toothpaste containing high fluoride concentrations can significantly reduce the prevalence and incidence of WSLs.27
Casein phosphopeptide-amorphic calcium phosphate complex (CPP-ACP) and casein phosphopeptide- amorphic calcium fluoride phosphate complex (CPP- ACFP) can increase the calcium and phosphate levels, prevent demineralisation and promote the remineralisation process. The complex has been commercialised as a remineralisation preparation for WSLs and dental caries.
As a minimally invasive restorative treatment, infiltrative resins penetrate the body of the WSLs, producing minimal enamel loss. They can mechanically stabilise the hydroxyapatite structure instead of allowing WSLs cavitation. Micro-abrasion and/or bleaching are also options to improve aesthetics after orthodontic treatment.
When caries cavitation occurs, preparation and restoration should be performed to manage the tooth decay, restore a smooth surface, and prevent plaque accumulation.
The present case report advises clinicians that clear aligner treatment could also significantly impact oral health. Poor oral hygiene during aligner therapy can cause adverse consequences even though it is theoretically a better alternative than fixed appliances in facilitating oral hygiene. Clinicians should be aware of WSL development during clear aligner orthodontic treatment, be mindful of risk factors, and oversee caries control.