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The non-operative resin treatment of proximal caries lesions Kim Ekstrand Stefania Martignon Azam Bakhshandeh David NJ Ricketts Dental Update 2024 39:9, 707-709.
Authors
KimEkstrand
DDS, PhD
Associate Professor, Section of Cariology & Endodontics and Paediatric Dentistry & Clinical Genetics, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
Assistant Professor, Section of Cariology & Endodontics and Paediatric Dentistry & Clinical Genetics, Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
Epidemiological data show that the prevalence of caries on proximal surfaces in need of operative treatment is very high around the world, both in the primary and the permanent dentition. This article presents two new treatment methods: proximal sealing and proximal infiltration. The indications are progressing proximal caries lesions, radiographically with a depth around the enamel-dentine junction. A small number of studies regarding the effect of sealing and infiltration on proximal caries versus the use of fluoride varnish, placebo treatment and flossing instructions have been carried out. About half of the studies disclose a not significant difference between test and control treatment. In the other half, the therapeutic effect is significant and corresponds to about 30% reduction in lesion progression. However, longitudinal studies of longer duration are lacking.
Clinical Relevance: Proximal sealing and proximal infiltration may have a place in the treatment of non-cavitated proximal lesions. Proximal caries is a problem in both primary and permanent dentitions. Proximal sealants or lesion infiltration are possible treatments.
Article
Scandinavian countries have well organized dental healthcare systems for children and adolescents, which are free of charge.1 That may be one important reason why children and adolescents in Scandinavia have lower caries prevalence, compared to children and adolescents in other high-income countries like France and the USA, or middle and lower income countries like Estonia, China and Cuba.2,3 Despite this, approximately 50% of Danish children develop caries that needs restorative treatment in the primary dentition, mainly affecting the proximal surfaces of primary molar teeth.4 Longitudinal radiographic studies from Sweden5 have shown that about 20% of 11-year-old children had proximal caries, but when the same individuals reached 22 years of age, the prevalence had risen to 70%. Studies from Denmark,6 Sweden,7 China8 and USA9 all show that caries on proximal surfaces continues to develop into adulthood. It can therefore be concluded that dentists around the world spend a considerable time on the preventive management, and unfortunately on the operative management, of proximal caries, in both the primary dentition as well as the permanent dentition.
Recently, two new treatment methods have been introduced, which aim to reduce caries progression in proximal surfaces, and ultimately avoid traditional restorative treatment. The first method is to seal the initial lesion with a resin, a method comparable to fissure sealing of the occlusal surface, and the second intends to let the resin infiltrate/penetrate into the pores of the lesion.
The purpose of this article is to describe and illustrate these methods, to provide information on their efficacy based on currently available literature and research, and to discuss their future place in contemporary clinical practice.
Indications for sealing/infiltration of proximal caries lesions
Based upon current knowledge, it is evident that the treatment option having the best prognosis for the management of cavitated stages of primary caries in proximal surfaces is conventional operative/restorative intervention.10 The clinical indication for sealing or infiltrating proximal caries lesions would therefore be the stages of lesion progression before cavitation occurs. Radiographically, this stage corresponds to radiolucency in enamel up to the enamel-dentine junction and possibly in the outer aspects of the dentine.11,12 It is important to remember that a radiograph alone is not an accurate predictor of non-cavitated/cavitated proximal lesions and, where doubt exists, temporary tooth separation may be required to allow direct clinical visual examination of the proximal surface to confirm a non-cavitated lesion. The condition of the interdental papilla and the adjacent marginal gingiva can also be used to assist the dental care professional in determining whether the proximal lesion, identified on a radiograph, is active and likely to progress or inactive and unlikely to progress.13 Thus, the gingiva next to active, plaque-covered lesions is likely to be inflamed. Proximal sealing or lesion infiltration should therefore be considered in patients with non-cavitated active lesions that have not responded to conventional primary prevention, such as enhanced oral hygiene procedures (regular use of interdental aids including floss and interdental brushes) and topical fluoride. Persistence of gingival inflammation after oral hygiene instructions is indicative of lesion progression. Strong proof is lesion progression on two radiographs taken with an interval of about a year.
Differences between sealing and lesion infiltration
Figures 1 a and b show the principal difference between the two treatment methods. By sealing, the resin is applied on to the surface of the lesion to create an external barrier; by infiltration, the resin should penetrate into the lesion's pore volume. In order to infiltrate the lesion, it is necessary to remove the surface zone of the lesion, which is done by the use of a strong acid, namely 15% hydrochloric acid for two minutes,14 followed by application of a low-viscosity resin for infiltration.
Figure 1. Diagrammatic representation of sealant versus infiltration techniques on a longitudinal section of a proximal early lesion. The sealant coloured yellow (a) is lying on top of the lesion, contrary to the infiltration (b), where the resin coloured yellow, penetrates into the lesion.
Method for proximal sealing
Figure 2 illustrates the proximal sealing method. An orthodontic separator is placed in the appropriate inter-proximal space for about two days to create sufficient space to allow direct access to the proximal surface. After this time the patient is re-called and the following takes place:
Figure 2. (a) Proximal sealing procedure: at the first visit a proximal lesion is identified on the BW (arrow), gingiva is probed carefully, and inflammation is found. Therefore a diagnosis of superficial active caries can be made; superficial because radiographically the lesion is in the enamel or in the outer third of the dentine. (b) An orthodontic separator band is placed between teeth. (c) At the second visit, the band is removed and the approximal tooth surface cleaned, and gentle probing is carried out to assess whether a cavity is present or not; (d) the adjacent tooth surface is isolated, in this case with a thin Teflon tape; (e) surface undergoes a conventional acid etch process (37% phosphoric acid); (f) lesion is sealed by covering it by a thin lay of resin followed by gentle air blowing, and (g) polished with a Sof-lex™ polish strip (3M ESPE, AG, Germany).
The lesion surface area is cleaned;
The lesion is examined by means of visual and tactile methods, to confirm that no cavity has occurred;
Rubber dam is placed, if considered necessary to obtain moisture control;
The adjacent surface is protected by a matrix band or Teflon tape (Polytetrafluoroethylene tape: this is a generic plumber's tape to seal water pipes) or by a traditional matrix band.
The lesion is etched with 37% phosphoric acid for 60 s;
The surface is rinsed and dried;
Alcohol is applied (99%) and the surface is dried with air until the alcohol disappears;
The resin is applied on the lesion with a micro-brush and dental floss is passed to rub the material into the lesion and to remove excess material;
The resin/dentine bonding agent is light cured;
Steps 8–9 are then repeated;
Finally, the surface is polished by means of a polishing strip.
Method for lesion infiltration
Figure 3 illustrates the infiltration method using the Icon technique (Icon~infiltration concept, DMG, Chemisch-Pharmazeutische Fabrik GmbH, Germany).
Figure 3. Infiltration procedure with Icon (infiltration concept). By this method, matrix bands are used, in which acid and resin are applied directly to the lesion, while the adjacent tooth surface is protected. (a) Active enamel/dentine lesion (arrowed); (b) rubber dam applied plus a wedge; (c) the matrix band; (d) filled with acid; (e, f) rinsed and dried and alcohol treatment; (g) the matrix band filled with resin infiltrant; (h) light-curing. With friendly permission of Professor Dr V Mendes Soviero, Rio de Janeiro, Brazil.
Unlike sealing, prior tooth separation is not necessary and the procedure can be carried out in one visit. The following procedure should be followed:
The lesion surface area is cleaned, eg by flossing;
Rubber dam is placed (mandatory);
A wedge is located in the proximal space to separate the teeth slightly;
A two-sided plastic foil, which is permeable on one side only, is placed inter-proximally: one side (non-permeable) protects the adjacent tooth and the other side with small orifices/pores allows escape of the materials (acid and resin) for direct application to the lesion surface;
The 15% hydrochloric acid-etching agent syringe is connected to the plastic foil appliance and the lesion is treated for 2 min and the plastic foil appliance is then removed;
The surface is rinsed for 30 s using a three-in-one water and air-spray syringe, ensuring good quality high volume suction. The lesion surface is dried with air;
Alcohol (99%) is applied for 30 seconds and the lesion surface is again dried with air;
A new two-sided plastic foil is placed with the infiltrate syringe attached and the resin is applied on to the lesion for 3 min;
The surface is gently air-dried;
Light-curing from buccal and lingual, 20 s each side;
A new two-sided plastic foil is placed with the infiltrate syringe attached and resin is re-applied on to the lesion area for 1 min, followed by a further buccal and lingual 20s light-cure.
Clinical trials
Tables 1 and 215–22 show information from studies that have investigated proximal sealing and proximal infiltration, respectively. It can be seen that most of the studies are of Split-mouth design with both test and control lesions in the same mouth. Such studies add weight to the fact that any difference between the treatments is more likely to be associated with the treatment itself than any other condition, such as use of different concentrations of fluoride toothpaste, etc between participants. Studies without such a design have an increased element of uncertainty regarding the reasons for the effect. All the test lesions in the studies cited were sealed or infiltrated with resin materials available on the market at the time. The control lesions in the studies were treated, either with bi-annual application of fluoride varnish, a placebo treatment, or instruction in flossing. The duration of the studies ranged from 1–3 years.
Authors, Year
Dentition, Tooth Types and Stage of Caries to be Included into the Study
Study Design
Sample
Treatment of Test and Control Lesions
Study Duration
Evaluation Method/s
Test vs Control Progression (%) Statistical Difference Therapeutic Effect (TE – when available)
Gomez et al, 200515
Permanent posterior teeth (radiolucency in enamel); 10–20 years old
Primary molar teeth, distal surface of 1st mesial/distal of 2nd (radioluency on enamel/dentine outer 1/3)
Split-mouth
Test: n=39; control: n=39
Test: infiltration (ICON pre-product, DMG) + F varnish; control: F varnish
1 year
Progression of score blinded
Progression: Test: 23% vs control: 61.5%; P<0.01. TE: 38%
Martignon et al, 201222
Permanent posterior teeth (radiolucency around EDJ/in dentine outer 1/3); 15–35 years old
Split-mouth
Test A: n=38; Test B: n=38; control: n=38
Test A: infiltration (ICON pre-product, DMG). Test B: sealing (Prime Bond NT, Dentsply); control placebo
3 years
Progression within same score blinded
Progression on:Test A: 37%,Test B: 42%; control C: 71%A vs C: P<0.005;B vs C: P<0.05; A vs B: NSTE: A vs C: 34%; B vs C: 29%
In the studies, carious lesions were recorded as to whether they had progressed, remained unchanged or regressed. The changes were investigated by comparing radiographs from baseline with radiographs from the follow-up visits; clinical data was used in only one study.21 Obvious progression of either test and/or control lesions into the middle third of dentine or deeper led to a decision to restore the surface and this was recorded as a failed treatment. In all studies (Tables 1 and 2), the examiners were blinded and hence did not know which lesions were test and control.
As can be seen from Tables 1 and 2, sealing and infiltration prevent more lesions from progressing than the control treatment. In five tests the differences between sealing and control treatment was not significant,15–18 while significant in 3 tests.16,19 With respect to infiltration, there was a significant difference between infiltration and control treatment in three tests20–22 and no significance in one test.20 The therapeutic effect measures the number of cases sealed/infiltrated which progressed versus the number of control cases which progressed during the study period. The therapeutic effect (TE), in those studies where there was a significant difference and where this statistic was mentioned, was around 30%.16,19,21,22 That is, in general, 30% more controls showed evidence of lesion progression compared to the test sealed or test infiltrated lesion. In one study, the effect between infiltrated lesions and sealed lesions was examined.22 Even though infiltration prevented more lesions from progressing than sealing, there was no significant difference between the two methods.
Discussion
It should be noted that the authors regard sealing as well as lesion infiltration of proximal caries lesions as the last preventive approach (secondary prevention) to avoid lesion progression and thus likely restorative therapy. Sealing and infiltration should only be used after other preventive methods, such as instruction in use of dental floss and local topical fluoride treatment has failed in the attempt to stop caries progression.
In the introduction we stated that there is still a rather high prevalence of proximal caries in the primary as well as the permanent dentition. Therefore, it is only natural to carry out studies regarding the two treatment types in both dentitions (Tables 1 and 2).
In children, one of the important questions is at what age can the child accept and tolerate such technically demanding procedures as proximal sealing or lesion infiltration? The study by Ekstrand et al21 showed that only 4% of the children with a mean age of 7½ years were unable to go through with the treatment owing to lack of co-operation. The remaining 96% of the children in the study went through with the treatment without any major problems. Time measurements showed that a complete session for the infiltration procedure took about 12 minutes on average. In Denmark, approximately 20% of 5-year-old children on a national level already have caries experience in primary molars which need restorative treatment (www.nexodent.com). This is one of the groups which could benefit from proximal sealing/infiltration, but whether such young children could go through with this treatment is questionable based upon the co-operation that is required. With the infiltration technique, where rubber dam should be regarded as mandatory, it is unlikely that such young children will tolerate the procedure. This having been said, one study on proximal sealants was carried out with cotton wool isolation only19 and still demonstrated a 25% therapeutic effect. A pragmatic approach would be only to consider such procedures for children older than 7 years and those younger children who have demonstrated good co-operation.
Caries lesions are histologically characterized by a minimally demineralized surface zone covering a considerably more demineralized body of the lesion beneath. The surface zone reflects the dynamic nature of the carious process and, in particular, surface remineralization.23 Resin infiltration of caries lesions differs from sealing, as the resin penetrates into the lesion and fills up a substantial part of the increased pore volume within the body of the lesion. Hence, it is necessary to remove the surface zone to allow the resin to penetrate. This must be done with acid treatment by means of 15% hydrochloric acid for 2-3 min.14 Sealing in the lesion only requires the surface zone to be partially eroded, in the form of a conventional acid etch pattern, to ensure adequate retention of the resin to the tooth surface. This can be achieved by etching the surface enamel by 37% phosphoric acid for 20–60 seconds.24
The resin materials used in the sealant studies discussed are those commonly commercially available. Use of 15% hydrochloric acid for the infiltration technique has the potential to damage the mucous membranes owing to its caustic nature; as such use of rubber dam is essential. Use of a wedge is also important as it will push the teeth apart slightly and additionally protect the proximal gingiva when left in place. The adjacent proximal tooth surface must also be protected against the acid. In the new Icon kit this is done by a two-sided plastic foil.
The separation for the sealing procedure can be done by use of an orthodontic separator band, which must be in place for about 48 hours. The main inconvenience of this technique is not that the band causes any discomfort,25 but rather the fact that the patient has to return for a second visit.
The present evidence shows that both methods (proximal sealants and proximal lesion infiltration) fail to arrest the lesion in a number of cases. In the study by Ekstrand et al,21 13 (30%) infiltrated lesions in primary molar teeth progressed, compared with the corresponding figures in the proximal sealant studies by Martignon et al, where 20 (27%) lesions in primary teeth19 and 16 (22%) sealed lesions in permanent teeth progressed.16 In all cases, progression was judged on radiographs.
The reasons for failures might be many, such as insufficient isolation and saliva control, undetected cavitation before sealing/infiltration, and the fact that it is difficult to be sure that the resin has completely covered or infiltrated the lesion. Caries risk may also play a significant role in failures; for example, the children in the study by Ekstrand et al21 were characterized as belonging to a high risk child population and the failures in this study were higher than in the other studies.
Despite the fact that failures can occur, it is the view of the authors that proximal sealing and proximal infiltration may have a place in the treatment of proximal lesions in the future. It is also important to point out that the studies presented in this article are clinical trials, where the treatments have been performed by specialists under very controlled conditions and are of relatively short duration. Whether such results can be extrapolated to the general practice setting will need further evaluation of studies carried out in primary care. Such studies that demonstrate comparable results will be necessary before dentists widely accept such techniques.
