Randomized in situ evaluation of surface polishing protocols on the caries-protective effect of resin Infiltrant

doi:10.21203/rs.3.rs-2104258/v1

Download PDF

Article

Randomized in situ evaluation of surface polishing protocols on the caries-protective effect of resin Infiltrant

https://doi.org/10.21203/rs.3.rs-2104258/v1

This work is licensed under a CC BY 4.0 License

You are reading this latest preprint version

The aim of this placebo-controlled randomized in situ study was to evaluate the effect of different surface polishing protocols on enamel roughness, bacterial adhesion and caries-protective effect of a resin infiltrant. Eighty-four bovine enamel samples having artificial caries lesions were treated with a resinous infiltrant and afterwards randomly dividided into five polishing protocols: aluminum oxide flexible disks (Al₂O₃-Disks), silicon carbide tips (SIC-Tips), silicon carbide brush (SIC-Brush), silicon carbide polyester strips (SIC-Strips) or no polishing [negative control (NC)]. Average surface roughness (Ra) was assessed by profilometry. Samples were mounted in palatal appliances under a mesh for biofilm accumulation. Fifteen volunteers wore the intraoral appliances (14-days) and cariogenic challenge was triggered by sucrose solutions. Biofilm formed was collected for microbiological analysis of caries-related bacteria (Streptococcus mutans, Lactobacillus acidophilus) and demineralization was assessed by cross-sectional microhardness. Mean Knoop hardness numbers (Kg/mm²) were plotted over lesion depth (µm) and area under the lesion curve was subtracted from sound enamel to determine demineralization (ΔS, Kg/mm²xµm). Data were analyzed by ANOVA and post-hoc comparisons (α=0.05). NC resulted in significantly higher Ra means than Al₂O₃-Disks and SIC-Strips. Bacterial counts were not significantly different between the groups (p>0.05). Regards ΔS means, however none of the groups were significantly different to NC (6,983.3 Kg/mm²xµm /CI:4,246.1–9,720.5, p>0.05). Conclusions: Polishing protocols (Al₂O₃-Disks, SIC-Strips) significantly decreseased roughness of infiltrated-enamel, however none of the polishing protocols could signicantly decrease bacterial counts nor resulted in significant less demineralization.

Currently a more biological approach to caries management is at least scientifically widely accepted. The understanding of caries as a multifactorial disease driven by a dysbiosis in the biofilm, the so called ecological plaque hypothesis, supports more holistic approaches for disease management including effective mechanical plaque control, diet modification and modulation of the remineralization ¹. Regarding the management of approximal non-cavitated caries lesions, the most actual consensus statements, systematic reviews and meta-analysis recommend both non- and micro-invasive treatment options ^2-4. The improvement of biofilm control via oral hygiene instructions and professional fluoride application (i.e., varnish) is a main component of the non-invasive approach. For patients at low caries risk, these measures should be enough to control the disease, yet, for patients at high caries risk, a higher probability and velocity of lesion progression might be expected, and in these cases the micro-invasive treatment options, like caries sealing and caries infiltration, have been recommended ².

However up to now, not much discussion has been provided on the susceptibility of infiltrated lesions to secondary caries or lesion progression due to increased plaque stagnation. Concurrently the control of biofilm formation or the predisposition of material surfaces, such as restorations, sealants and infiltrants to accumulate biofilm is known to play a significant role in caries control. Specially as surface irregularities in materials not only predispose for higher biofilm accumulation ^5,6, but also act like niches where biofilm may grow undisturbed from mechanical actions of occlusal function, friction from cheeks, tongue, and oral hygiene measures ⁷.

A recent systematic review also confirms that considering composite resins polishing techniques may decrease bacterial adhesion through decrease of surface roughness ⁸. Besides surface roughness, several surface properties can influence bacterial adhesion to restorative or sealing/infiltrant materials surfaces, i.e. surface free energy (surface wettability), charge, polarity, and morphology ⁶. However, surface roughness seems to be the most important and most studied one, especially as regards the accumulation and composition of the biofilm ^7,9. Moreover, some years ago, a threshold value for average surface roughness (Ra) of 0.2 µm has been proposed, indicating that dental material surfaces with roughness means below this value should have no impact on bacterial adhesion ¹⁰. However, this concept has been contested recently, since the influence of roughness on bacterial adhesion seems to be more related to roughness range rather than a threshold. ¹¹ In addition factors like type of material and study design may also influence bacterial adhesion, with studies including formation of salivary pellicle, in situ or in vivo, having a clear advantage of better simulating the clinical conditions, where early colonizers first attach to salivary pellicle and the latter may also modify the surface of properties of the materials ^6,12

Incipient/ white-spot carious lesions are known to show higher roughness than sound enamel, due to increased episodes of enamel dissolution ¹³ and resin infiltration of these lesions indeed decreases their surface roughness. Nevertheless, infiltrated caries lesions still have significantly higher roughness than non-treated sound enamel ¹⁴. After the hydrochloric acid etching, opening so the lesion micropores and the lesion body for the infiltration of low-viscosity monomers, an increased lesion surface roughness is present ¹⁵. The resin infiltration afterwards has been shown to effectively fill up this micro-porosities ¹⁶, however without recovering of the initial roughness values ^15,17. As increased surface roughness among other factors play an important role in dental plaque accumulation and biofilm formation ^5,6,12, which in turn can favour the occurrence of caries adjacent to restorations and sealants (CARS) ³, this factor might be of clinical relevance for the long-term treatment survival rate. This leads to the question of, whether surface polishing procedures, a common clinical step in restorative treatment, may be also indispensable for the long-term success of caries infiltration and prevention of caries around the infiltrated lesions as well as a more holistic caries control.

Currently, only one study have investigated the influence of polishing on the recovery of enamel surface roughness after resin infiltration of incipient carious lesions ¹⁵. The polishing of infiltrated lesions, solely with one type of polishing strip showed no significant benefit regarding surface roughness and as compared to the non-polished infiltrated lesion ¹⁵; even if the effect of the increased lesion surface roughness on bacterial adhesion was not tested. In fact, bacterial adhesion has also been tested only in one study including resin infiltration of incipient carious lesion, but without any polishing procedure after resin infiltration ¹⁸.

In summary there is clear evidence that resin infiltration prevents caries progression clinically, but also that it increases lesion surface roughness, which (at least in theory) favours higher plaque accumulation. Until now no clinical recommendation has been made in the current clinical guidelines ¹⁹, meta-analyses ² and consensus reports ³ as regards how infiltrated approximal and buccal non-cavitated caries lesions should be polished in order to decrease surface roughness, plaque accumulation and the consequent increased risk of developing both gingivitis and secondary caries. Therefore, it is still unclear if certain polishing protocols after carious lesion infiltration with low-monomers infiltrant, could further considerably decrease enamel surface roughness as compared to non-polished infiltrated lesions and additionally decrease bacterial adhesion. Thus, the aim of this placebo-controlled randomized in situ study was to evaluate the effect of different surface polishing protocols o enamel surface roughness, bacterial adhesion and caries-protective effect of an infiltrant. It was thus hypothesized that polishing of resin-infiltrated incipient carious lesions would cause for all protocols a decrease in average surface roughness, adhesion of caries-associated bacteria and less in situ demineralization than the non-polished negative control.

This study was conducted according to the principles of the declaration of Helsinki and all experimental protocols were approved by the local Research and Ethical Committee of the Christus University Center (Protocol # 2758611). All participants signed a written informed consent before the start of the study.

Study design and Subjects

This study was a single-center, placebo-controlled, double-blinded (volunteer and examiner) randomized in situ study composed of one single- factor (polishing types), at 5 levels (polishing protocols). Randomization and blinding were performed by the supervisor of the study using the random sequences function of the Software Excel. The total duration of the intraoral phase was 14 days (Fig. 1) with a 1-week wash-in period preceding it, as previously described ^20-22.

The volunteers were additionally informed to avoid consuming high fluoride-containing food, such as fluoridated salt, green/black tea and fish. At the beginning of each phase, the volunteers were also extensively trained to follow the study instructions. The intraoral appliances were worn during the whole day except for meals and oral hygiene. Through the whole study and additionally in the wash-in phase, individual oral hygiene was performed with a fluoride toothpaste (NaF, 1.450 ppm F^-, Colgate Total 12, São Paulo, Brazil), without the appliances in situ. After meals, 20 min were elapsed before mouth appliance reinsertion.

Sample Size

The sample size was calculated based on the results of a previous study evaluating the inhibition of caries progression after resin infiltration in situ ²³. According to that, mean enamel mineral loss after the intraoral phase of 6,261 (SD= 2,009) vol% x µm for the negative control and 2,559 (SD= 1,178) vol%x µm for the infiltrated group would be expected. The tooth was considered as experimental unit and to obtain a power of 80%, a sample size of fourteen enamel blocks per treatment group was calculated (two-sided, α=0.05). In order to account for a possible dropout, 15 specimens/groups were then included in the experiments.

Fifteen young adult volunteers (9 women, 6 men, aged 18-22 years), were recruited for the study. All subjects lived in Fortaleza, Brazil (fluoride concentration in tap water of approximately 0.8 mg/l) and met the following inclusion criteria: the ability to wear an intraoral palatal device for 24 h per day, except at eating and brushing times; no evidence of active caries, or periodontal disease; no signs of decreased salivary flow rate and the ability to comply with the study protocol. Exclusion criteria were any medical condition potentially interfering with the subject’s health; use of orthodontic appliance; pregnancy or breastfeeding and absence of compliance to the study protocol.

Specimens

Seventy-five enamel blocks of 4 × 4 × 2 mm, disinfected as previously described ^24,25 were cut from labial central area of bovine incisor crowns (Isomet, Buehler, Illinois, USA). The enamel surface was serially polished using silicon carbide papers (grits #800, #1200, and #4000, Buehler, USA) under water cooling and polishing cloths with a 1-µm diamond suspension (Buehler, USA). After each polishing steps, the specimens were washed in ultrasonication bath containing deionized water for 3 minutes. The surface microhardness of all enamel blocks was determined with a Knoop indenter (6 indentations in the center of the specimens: 25 g load for 15 s), as previously described by Zero et al. ²⁶. Eighty-four enamel specimens were selected (average knoop hardness number (KHN): 252.69 ± 50.53 KHN), after discarding 6 blocks that presented outlier values. All specimens were examined under a stereo microscope to ensure the absence of hypomineralized areas or surface defects ²⁷ and were stored at 100% of humidity in a box containing deionized water, throughout the study, except for the time they were in situ.

Artificial Caries Lesions

All selected specimens were all were laterally protected with acid resistant varnish (Colorama-CEIL, São Paulo, SP, Brazil), leaving only the labial enamel surface of the specimens exposed. Afterwards they were submitted to a well-stablished pH-cycling model for 8 days, in order to create artificial white-spot lesions, as previously described ²⁸. Shortly, each cycle consisted of 4 h immersion in the demineralization solution followed by 20 h in the remineralization solution at 37 °C. The demineralization solution was composed of (50 mmol/lactate buffer pH 5.0, containing 1.28 mmol/L Ca, 0.74 mmol/L Pi and 0.03 μg F/ml prepared to form the Ca(NO₃) salt 2.4 H₂O, KH₂PO₄ and NaF) (100 ml/16 mm² of enamel. And the chemical composition of remineralization solution was 1.5 mmol/Ca, 0.9 mmol/P, 150 mmol/KCl and 0.05 μgF/mL in 0.01 mmol/L Tris buffer (pH 7.0 / 37 ° C) (2.5 ml solution/mm² enamel surface) ²⁸. Twice a day (before and after immersion in the demineralization solution), the blocks were washed with deionized water for 5 min and under agitation, and on the fourth day, the demin- and remineralization solutions were renewed with fresh ones. After the end of the pH-cycling, the blocks were kept immersed in remineralization solution for 24 hours ²⁸.

Resin Infiltration of Caries Lesions

After lesion formation all specimens were washed in running water and dried with sterile gauze. Subsequently micro-invasively treatment by the application of resinous infiltrating agent (ICON^®, Dental Milestones Guaranteed DMG, Hamburg, Germany) was carried out, according to the manufacturer's protocol and as previously described ²⁹.

Surface Polishing Protocols (Treatments)

After that, the specimens were randomly divided, using an Excel-Sheet with random sequence of numbers, into five groups receiving the following polishing treatments:

No polishing, as a negative control group (NC)
polishing with aluminium oxide flexible disks (Al₂O₃-Disks), Sof-Lex Pop On^®
polishing with silicon carbide tips (SIC-Tips), Astropol^®
polishing with silicon carbide brush (SIC-Brush), Optishine^®
polishing silicon carbide polyester strips (SIC-Strips), Epitex^®

All polishing protocols were performed by only one operator, for the same amount of time, in a pre-tested manner as well as following the manufacturers' instructions. Further details are described in Table 1.

Table 1. Detailed description of polishing groups, trademarks and adopted application protocols. Grit sizes are provided for all instruments in µm.

Groups	Polishing Systems	Protocols*
NC	Negative control No polishing	Only washing with water for 30 s
Al₂O₃-Disks	Aluminium oxide flexible disks Sof-Lex Pop On^® (3M–ESPE, Minnesota, USA)	Discs: Light orange (thin), grit size: 5.72 μm Yellow (ultrafine), grit size: 1.68 μm - Movements: Intermittent, unidirectional - Time: 15 s each, in total 30 s - Application of air and water jets between one disk and another
SIC-Tips	Silicone Carbide Tips Astropol^® (Ivoclar-Vivadent, Schaan, Liechtenstein)	Tip: Pink silicone tip, Silicon carbide, aluminium oxide, titanium oxide, and iron oxide, grit size: 3.5 μm - Movements: Intermittent, unidirectional with abundant water - Time: 30 s
SIC-Brush	Silicon Carbide Brush Optishine^® (KERR, California, EUA)	Brush: Silicon carbide abrasive particles embedded in the bristles, single-step system, grit size: 0.4 µm -Movements: Intermittent, unidirectional with abundant water -Time: 30 s
SIC-Strips	Silicon Carbide Polyester Strips Epitex^® – GC Corporation, Bunkyo-ku, Tokyo, JAPAN	Sandpaper: Fine (Gray), grit size: F-800 ca. 6.5 µm Extra Fine (Pink), grit size: F-1200 ca. 3.0 µm Movements: Back and forth Time: 15 s each, in total 30 s

*For all protocols, the discs, tips, brushes, or strips were changed after the polishing of each 3^rd specimen.

Surface roughness

In order to evaluate the effect of the different polishing systems on the surface characteristics of infiltrated enamel all specimens were subjected to a surface roughness analysis (Fig. 2) using a contact profilometer (Hommel-Etamic W10, Schwenningem, Germany). The device has an accuracy of 0.01 µm, and the diamond stylus has a radius of 5 µm. Measurements were done in the center of the specimens at a constant speed of 0.15 mm/s and under a force of 0.8 mN. The average roughness values (Ra) were obtained after three successive scannings, located at 100 μm distance to each other, as previously described ^30,31. An arithmetic mean of the values measured was considered the value (Ra) in μm for each specimen.

Palatal Appliances

After hard and soft tissue examination intraoral palatal devices of acrylic resin were prepared for each volunteer. In each palatal device, 5 niches were created, where the specimens containing the infiltrated caries lesions were fixed (Fig.2). A free space of 1.0 mm over the specimens and the plastic mesh covering then was preserved, in order to allow for biofilm accumulation. The mesh net also protected the biofilm against mechanical disturbances ^21,24.

Intraoral Phase

To trigger a cariogenic challenge, the volunteers dripped 10% sucrose solution over each specimen 8 times a day, for 14 days (Fig. 2). In total the volunteers wore the intraoral appliances for 5 phases of 14 days each, with continuous in situ exposure except during meals and oral hygiene, meaning a total wearing time of 22-23 h/day.

Cross-Sectional Microhardness Analysis

After the in situ cariogenic challenge and biofilm collection, a longitudinal section was performed in the center of each specimen. One of the halves of each specimen was embedded in acrylic resin, the cut surface being exposed. The cut surfaces were subsequently serially polished as described in the specimen preparation section and the cross-sectional microhardness was measured. For this, two lines of fourteen Knoop indentations were done at 25 g load for 5 s ^20,32,33. The two lines of indentations were located 100 μm apart from each other ³⁴. Within each sequence, the first ten indentations were spaced 10 µm from the previous one and the last ones were spaced at 20 μm distance (10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180 μm distance from the enamel surface) ³⁵. The mean Knoop hardness number (Kg/mm²) of the two rows at each distance from the surface were then averaged and plotted over the lesion depth (µm). The data set of each artificial caries lesion was curve-fitted ³³, and the area under the lesion tracing was calculated and subtracted from the area under the curve of sound enamel mean values to give the parameter (DS, Kg/mm² x µm) ³². As a linear relationship between cross-sectional microhardness and mineral content of enamel measured by transversal microradiography methods has been demonstrated ³³.

Microbiological analysis

Microbiological analysis of the biofilm formed on each specimen was performed, in order to evaluate the effect of polishing of the resin infiltrants on the adhesion of caries-associated bacteria species ³⁶. A biofilm sample from each specimen was collected. The obtained suspension (addition of 0.9% NaCl solution (1 ml/mg of biofilm) was diluted in decimal series and inoculated in triplicate in blood agar culture media to determine total microorganisms (TM), and MSKB (90g mitis salivarius dehydrated agar; 1ml 1% potassium tellurite; 20% w/v sorbitol; 1ug/ml kanamycin monosulfate; 0.1U/ml bacitracin) for counting Streptococcus mutans and Man Rogosa Sharpe agar for counting Lactobacillus acidophilus (kept for 48 hours in an oven at 37 °C with a partial pressure of 5% CO₂) for 48 hours, the ratio of colony forming units (CFU) per milligram of biofilm was established (CFU/mg).

Statistical Analysis

Normal distribution of all collected data was assessed using the Shapiro-Wilks statistical test as 5% significance level. As the average surface roughness data were not normally distributed, they were analysed using a Kruskal-Wallis test and post hoc comparisons. Data obtained from the cross-sectional microhardness and DS analyses were analysed by means of a one-way ANOVA and Tukey´s post hoc comparisons to detect differences between the treatment groups. For the microbiological analysis, the variables of colony forming units (CFU) of each group were logarithmically transformed and then analysed by means of ANOVA and Tukey-test for post hoc comparisons. All tests were conducted at a significance level of 5% using the Statistical Package for the Social Sciences (SPSS 22.0) for Windows.

Surface Roughness

The results of the surface roughness analysis after each polishing protocol are shown in Fig. 3. In general, there was a significant effect of the type of polishing protocol on enamel surface roughness (p = 0.001). Statistically significant difference was found between NC and Al₂O₃-disks (p <0.001) and between NC and SIC-strips (p = 0.040). Among the test groups, meaning the different polishing protocols, no significant difference was observed (p>0.05)

Cross-Sectional Microhardness Analysis

Regarding protection from demineralization under the in situ cariogenic challenge, The lowest DS mean (Kg/mm²Xµm) was observed for Al₂O₃-Disk (5,931.9/CI: 1,769.3–10,094.6), however none of the groups were significantly different to NC (6,983.3/CI: 4,246.1–9,720.5, p>0.05) (Table 2, Fig. 4).

Table 2. Means and 95% confidence intervals of the cross-sectional microhardness (Knoop hardness) measurements.

	Groups	Delta S
		Mean (Ds, Kg/mm²x µm)	95% CI	*
Negative Control	NC	6,983.3	(4,246.10 – 9,720.52)	a
Aluminium oxide flexible disks	Al₂O₃-Disks	5,931.9	(1,769.24 – 10,094.57)	a
Silicon Carbide Tips	SIC-Tips	7,460.5	(4,053.06 – 10,867.92)	a
Silicon Carbide Brush	SIC-Brush	7,783.9	(3,466.34 – 12,101.43)	a
Silicon Carbide Polyester Strips	SIC-Strips	8,845.5	(4,733.45 – 12,957.52)	a

*ANOVA statistical analysis showed no significantly difference between the groups (p=0.783)

Microbiological Analysis

The logarithms of the microbiological count after polishing in the in situ microbiological assay can be found in figure 5. In all of the bacterial counts investigated, namely Streptococcus mutans, Lactobacillus acidophilus and total microorganisms there was no statistical difference between the groups (p = 0.89, p = 0.37, p=0.58 respectively).

The present study evaluated for the first time the efficacy of polishing protocols after resin infiltration using an in situ model. The results showed that infiltrated and subsequently polished enamel lesions do not demineralize significantly less compared to unpolished lesions. Moreover, bacterial adhesion of caries-associated bacteria, like Streptococcus mutans and Lactobacillus acidophilus, but also of total bacterial was not significantly reduced, partially rejecting the formulated study hypothesis. However, average surface roughness of resin-infiltrated enamel caries lesions was significantly reduced after polishing with Al₂O₃-Disks and SIC-Strips confirming what was initially hypothesized; at least for these two protocols.

Currently, there are little evidence from in vitro and only limited indirect evidence from clinical studies as regards the effect of solely resin infiltration or infiltration followed by several polishing protocols on surface roughness and bacterial adhesion of infiltrated carious lesions. The significantly reduced surface roughness observed after polishing with Al₂O₃-Disks and SIC-Strips are not totally in agreement with the only one in vitro study investigating polishing of resin-infiltrated lesions. In the study from Mueller, et al. ¹⁵ polishing the incipient lesions with only one type of polishing system, namely polishing strips (coarse, medium, fine and superfine, each: 15 s, total time:60 s), after light curing of the resin infiltrant resulted in average surface roughness means not significantly different to the non-polished groups. The differences in the results may be related to the fact that the caries lesions in the mentioned study ¹⁵ were much deeper than in our study, implicating in the presence of much larger surface pores, which may have resulted in much higher initial surface roughness and a more difficult baseline situation for achieving a high degree of polishing. Furthermore, the study design may have been also an influence factor, as the present study the cariogenic challenge was performed in situ, including the influence of the salivary pellicle, and in the previous study only in vitro simulations were performed.

As regards the bacterial adhesion to the best of our knowledge this was the first study investigating bacterial adhesion of two caries-associated bacteria (S. mutans and L. acidophilus) in situ and after polishing of resin-infiltrated lesions. In fact, the only previous study investigating bacterial adhesion after a resin infiltration procedure, did not included any polishing afterwards, while investigating only one bacteria species, namely Streptococcus mutans ¹⁸. In this way the approaches are not directly comparable, but anyway also without polishing there was a slightly reduced adhesion of S. mutans, which was not significantly different to the non-treated control ¹⁸. This indicates a tendency towards absence of an impact of resin infiltration on biofilm formation. Nevertheless, a better understanding of the influence of resin infiltration on bacterial adhesion is still needed and must be further investigated. Moreover, the present results must be interpreted with caution as other cariogenic species play a key role in a cariogenic biofilm or in the transition to dysbiosis of the microbiome ¹.

Another aspect interest to observe is that even in the groups causing a significant decrease in surface roughness, like Al₂O₃-Disks and SIC-Strips, this decrease was not accompanied by a decrease in the bacterial adhesion over these more polished surfaces. This was somehow unexpected, but at the same time shows that surface roughness is not the solely topography parameter impacting bacterial adhesion. Indeed, also surface free energy, charge, polarity and morphology has been shown to substantially influence bacterial adhesion and growth ^6,7. Moreover, the means of average surface roughness (Ra) in the present study varied from 0.3–0.6 µm, slightly above a limit of 0.2 µm, over which surfaces were supposed to favour higher bacterial adhesion ¹⁰. This is also in agreement with a recent systematic review contesting this threshold value for bacterial adhesion over dental material surfaces ¹¹. In addition factors like type of material and study design may also influence bacterial adhesion, with studies including formation of salivary pellicle, in situ or in vivo, having a clear advantage of better simulating the clinical conditions, where early colonizers first attach to salivary pellicle and the latter may also modify the surface of properties of the materials ^6,12

For sure the use of bovine enamel samples provides similar but not equal demineralization responses as human enamel and thus represent a limitation of the results shown. However, at the same time, the study design allowed for the first time an analysis of the influence of polishing of resin-infiltrated incipient caries lesions on surface roughness, bacterial adhesion, and the caries protective effect within the oral cavity and under cariogenic conditions. This represents an important advantage of the model as, among other reasons, it is well known that bacterial growth over enamel or restoration surfaces in highly influenced by the presence or absence of a naturally formed salivary pellicle ⁶. Thus, a better clinical simulation of the biofilm film formed clinically was achieved. Nonetheless, the clinical efficacy of polishing resin-infiltrated caries lesions must still be investigated under a more severe cariogenic model, including longer sucrose challenges and/or longer periods in situ.

Although the present results showed that polishing neither influenced the caries-protective effect of resin infiltration nor the bacterial adhesion, from a clinical point of view and specially for labial white-spot lesions infiltrated for masking the whitish appearance, it is still probably more reasonable to polish then anyway. Data from previous clinical studies on this application showed that labial lesions may suffer from long-term staining, when not polished ^37–39. Moreover, contrary to the clinical studies on approximal lesions, which all did not report polishing procedures ^29,40−43, for labial lesions most of the clinical studies have been performed including polishing steps after light curing of the infiltrant ³⁷. In the study from Kobbe et al. 2019 for example polishing with disks (Sof-Lex) and a polishing brush (Okklubrush) were included and resulted in non-staining in the short-term follow-up.

It was shown for the first time in a pre-clinical intraoral model that some polishing protocols influenced surface roughness, while not significantly affecting neither bacterial adhesion nor enamel demineralization, under the conditions of this study. In this way, not contradicting the clinical recommendation of only removing surplus infiltrant material before light curing. However, one must bear in mind that this question of plaque stagnation over resin-infiltrated should be further investigated either in vivo or with in situ models including longer and more aggressive cariogenic challenges as well as including other polishing protocols before a clinical recommendation as regards the polishing need after infiltration of both buccal as well as approximal caries lesions can be made.

Thus, in conlcusion polishing protocols including Al₂O₃-Disks and SIC-strips significantly decreased average roughness of resin-infiltrated caries lesions in enamel. However, none of the polishing protocols could significantly decrease the bacterial counts nor resulted in significantly less demineralization than the non-polished control.

Data availability

The data collected and analysed in this paper is available from the corresponding author upon reasonable request.

Author contributions statement

M.E.O and J.P.M.L. developed the study design and methodology, T.M.A.Z.C.R., A.R.R.F, and C.N.N.T. conducted the experiments and acquired data, G.C., R.J.W., H.M.L., M.E.O., V.F.P., J.S.M. and J.P.M.L. analysed the data, M.E.O., G.C., J.S.M., V.F.P., J.P.M.L. were involved in interpretation of the data, M.E.O and J.P.M.L. wrote the paper and all authors revised the manuscript.

Additional Information (Competing Interests)

HML is appointed as inventors US and European patents for an infiltration technique for dental caries lesions, held by Charité Universitätsmedizin Berlin, and receive royalties from DMG. All other authors declare no competing financial and non-financial interests.

Marsh, P. D. In Sickness and in Health-What Does the Oral Microbiome Mean to Us? An Ecological Perspective. Advances in dental research 29, 60-65, doi:10.1177/0022034517735295 (2018).
Splieth, C. H., Kanzow, P., Wiegand, A., Schmoeckel, J. & Jablonski-Momeni, A. How to intervene in the caries process: proximal caries in adolescents and adults-a systematic review and meta-analysis. Clinical oral investigations 24, 1623-1636, doi:10.1007/s00784-020-03201-y (2020).
Schwendicke, F. et al. How to intervene in the caries process in adults: proximal and secondary caries? An EFCD-ORCA-DGZ expert Delphi consensus statement. Clinical oral investigations 24, 3315-3321, doi:10.1007/s00784-020-03431-0 (2020).
Dorri, M., Dunne, S. M., Walsh, T. & Schwendicke, F. Micro-invasive interventions for managing proximal dental decay in primary and permanent teeth. Cochrane Database Syst Rev, CD010431, doi:10.1002/14651858.CD010431.pub2 (2015).
Hannig, C. & Hannig, M. The oral cavity--a key system to understand substratum-dependent bioadhesion on solid surfaces in man. Clinical oral investigations 13, 123-139, doi:10.1007/s00784-008-0243-3 (2009).
Sterzenbach, T., Helbig, R., Hannig, C. & Hannig, M. Bioadhesion in the oral cavity and approaches for biofilm management by surface modifications. Clinical oral investigations 24, 4237-4260, doi:10.1007/s00784-020-03646-1 (2020).
Cheng, Y., Feng, G. & Moraru, C. I. Micro- and Nanotopography Sensitive Bacterial Attachment Mechanisms: A Review. Front Microbiol 10, 191, doi:10.3389/fmicb.2019.00191 (2019).
Nedeljkovic, I., Teughels, W., De Munck, J., Van Meerbeek, B. & Van Landuyt, K. L. Is secondary caries with composites a material-based problem? Dental materials : official publication of the Academy of Dental Materials 31, e247-277, doi:10.1016/j.dental.2015.09.001 (2015).
Quirynen, M. & Bollen, C. M. The influence of surface roughness and surface-free energy on supra- and subgingival plaque formation in man. A review of the literature. Journal of clinical periodontology 22, 1-14, doi:10.1111/j.1600-051x.1995.tb01765.x (1995).
Bollen, C. M., Lambrechts, P. & Quirynen, M. Comparison of surface roughness of oral hard materials to the threshold surface roughness for bacterial plaque retention: a review of the literature. Dental materials : official publication of the Academy of Dental Materials 13, 258-269, doi:10.1016/s0109-5641(97)80038-3 (1997).
Dutra, D., Pereira, G., Kantorski, K. Z., Valandro, L. F. & Zanatta, F. B. Does Finishing and Polishing of Restorative Materials Affect Bacterial Adhesion and Biofilm Formation? A Systematic Review. Operative dentistry 43, E37-E52, doi:10.2341/17-073-L (2018).
Song, F., Koo, H. & Ren, D. Effects of Material Properties on Bacterial Adhesion and Biofilm Formation. J Dent Res 94, 1027-1034, doi:10.1177/0022034515587690 (2015).
Fejerskov O, N. B., Kidd EAM in Dental Caries: The Disease and Its Clinical Management. (ed Kidd EAM (eds) Fejerskov O) Ch. Chapter 3, 20--48 (Blackwell Munksgaard, 2008).
Yazkan, B. & Ermis, R. B. Effect of resin infiltration and microabrasion on the microhardness, surface roughness and morphology of incipient carious lesions. Acta odontologica Scandinavica 76, 473-481, doi:10.1080/00016357.2018.1437217 (2018).
Mueller, J., Yang, F., Neumann, K. & Kielbassa, A. M. Surface tridimensional topography analysis of materials and finishing procedures after resinous infiltration of subsurface bovine enamel lesions. Quintessence international 42, 135-147 (2011).
Meyer-Lueckel, H. & Paris, S. Infiltration of natural caries lesions with experimental resins differing in penetration coefficients and ethanol addition. Caries Res 44, 408-414, doi:10.1159/000318223 (2010).
Ulrich, I., Mueller, J., Wolgin, M., Frank, W. & Kielbassa, A. M. Tridimensional surface roughness analysis after resin infiltration of (deproteinized) natural subsurface carious lesions. Clinical oral investigations 19, 1473-1483, doi:10.1007/s00784-014-1372-5 (2015).
Arslan, S. et al. Effect of resin infiltration on enamel surface properties and Streptococcus mutans adhesion to artificial enamel lesions. Dental materials journal 34, 25-30, doi:10.4012/dmj.2014-078 (2015).
Giacaman, R. Evidence-based Approaches for the Management of the Proximal Lesion in Adults. Summary from the ORCA/EFCD/DGZ Consensus. . Web Summaries of the European Organisation for Caries Research (ORCA) (2022). <https://www.orca-caries-research.org/sites/default/files/inline-files/Giacaman%20-%20How%20to%20Manage%20Caries%20in%20Adults.pdf>.
Featherstone, J. D. & Zero, D. T. An in situ model for simultaneous assessment of inhibition of demineralization and enhancement of remineralization. J Dent Res 71 Spec No, 804-810 (1992).
Zero, D. T. In situ caries models. Advances in dental research 9, 214-230; discussion 231-214 (1995).
Lima, J. P. et al. Evaluation of the antimicrobial effect of photodynamic antimicrobial therapy in an in situ model of dentine caries. Eur J Oral Sci 117, 568-574, doi:10.1111/j.1600-0722.2009.00662.x (2009).
Paris, S. & Meyer-Lueckel, H. Inhibition of caries progression by resin infiltration in situ. Caries Res 44, 47-54, doi:10.1159/000275917 (2010).
Hara, A. T., Queiroz, C. S., Paes Leme, A. F., Serra, M. C. & Cury, J. A. Caries progression and inhibition in human and bovine root dentine in situ. Caries Res 37, 339-344, doi:10.1159/000072165 CRE2003037005339 [pii] (2003).
Souza, J. G. et al. Calcium Prerinse before Fluoride Rinse Reduces Enamel Demineralization: An in situ Caries Study. Caries Res 50, 372-377, doi:10.1159/000446407 (2016).
Zero, D. T. et al. An improved intra-oral enamel demineralization test model for the study of dental caries. J Dent Res 71 Spec No, 871-878 (1992).
Ramalho, K. M. et al. Randomized in situ study on the efficacy of CO2 laser irradiation in increasing enamel erosion resistance. Clinical oral investigations 23, 2103-2112, doi:10.1007/s00784-018-2648-y (2019).
Molina, G. F. et al. Lead deposition in bovine enamel during a pH-cycling regimen simulating the caries process. Caries Res 45, 469-474, doi:10.1159/000330602 (2011).
Meyer-Lueckel, H. et al. Proximal caries infiltration - Pragmatic RCT with 4 years of follow-up. J Dent 111, 103733, doi:10.1016/j.jdent.2021.103733 (2021).
Esteves-Oliveira, M. et al. Rehardening of acid-softened enamel and prevention of enamel softening through CO₂ laser irradiation. J. Dent 39, 414-421, doi:10.1016/j.jdent.2011.03.006 (2011).
Esteves-Oliveira, M. et al. A New Laser-Processing Strategy for Improving Enamel Erosion Resistance. J Dent Res 96, 1168-1175, doi:10.1177/0022034517718532 (2017).
Cury, J. A., do Amaral, R. C., Tenuta, L. M., Del Bel Cury, A. A. & Tabchoury, C. P. Low-fluoride toothpaste and deciduous enamel demineralization under biofilm accumulation and sucrose exposure. Eur J Oral Sci 118, 370-375, doi:10.1111/j.1600-0722.2010.00745.x (2010).
Featherstone, J. D., ten Cate, J. M., Shariati, M. & Arends, J. Comparison of artificial caries-like lesions by quantitative microradiography and microhardness profiles. Caries Res 17, 385-391, doi:10.1159/000260692 (1983).
Melo, M. A. S., Morais, W. A., Passos, V. F., Lima, J. P. M. & Rodrigues, L. K. A. Fluoride releasing and enamel demineralization around orthodontic brackets by fluoride-releasing composite containing nanoparticles. Clinical oral investigations 18, 1343-1350, doi:10.1007/s00784-013-1073-5 (2014).
Calvo, A. F. et al. Effect of acidulated phosphate fluoride gel application time on enamel demineralization of deciduous and permanent teeth. Caries Res 46, 31-37, doi:10.1159/000335125 (2012).
Henne, K. et al. Analysis of Bacterial Activity in Sound and Cariogenic Biofilm: A Pilot in vivo Study. Caries Research 50, 480-488, doi:10.1159/000448485 (2016).
Kobbe, C., Fritz, U., Wierichs, R. J. & Meyer-Lueckel, H. Evaluation of the value of re-wetting prior to resin infiltration of post-orthodontic caries lesions. J Dent 91, 103243, doi:10.1016/j.jdent.2019.103243 (2019).
Mazur, M. et al. In-vivo colour stability of enamel after ICON(R) treatment at 6 years of follow-up: A prospective single center study. J Dent 122, 103943, doi:10.1016/j.jdent.2021.103943 (2022).
Knaup, I. et al. Correlation of quantitative light-induced fluorescence and qualitative visual rating in infiltrated post-orthodontic white spot lesions. European Journal of Orthodontics doi: 10.1093/ejo/cjac051, doi:doi: 10.1093/ejo/cjac051 (2022).
Martignon, S., Ekstrand, K. R. & Ellwood, R. Efficacy of sealing proximal early active lesions: an 18-month clinical study evaluated by conventional and subtraction radiography. Caries Res 40, 382-388, doi:10.1159/000094282 (2006).
Arthur, R. A. et al. Proximal carious lesions infiltration-a 3-year follow-up study of a randomized controlled clinical trial. Clinical oral investigations 22, 469-474, doi:10.1007/s00784-017-2135-x (2018).
Peters, M. C., Hopkins, A. R., Jr., Zhu, L. & Yu, Q. Efficacy of Proximal Resin Infiltration on Caries Inhibition: Results from a 3-Year Randomized Controlled Clinical Trial. J Dent Res 98, 1497-1502, doi:10.1177/0022034519876853 (2019).
Paris, S., Bitter, K., Krois, J. & Meyer-Lueckel, H. Seven-year-efficacy of proximal caries infiltration - Randomized clinical trial. J Dent 93, 103277, doi:10.1016/j.jdent.2020.103277 (2020).

Competing interest reported. HML is appointed as inventors US and European patents for an infiltration technique for dental caries lesions, held by Charité Universitätsmedizin Berlin, and receive royalties from DMG. All other authors declare no competing financial and non-financial interests.

Download PDF

Editorial decision: Major revision
01 Nov, 2022
Reviews received at journal
26 Oct, 2022
Reviewers agreed at journal
18 Oct, 2022
Reviewers invited by journal
17 Oct, 2022
Editor assigned by journal
13 Oct, 2022
Editor invited by journal
05 Oct, 2022
Submission checks completed at journal
05 Oct, 2022
First submitted to journal
26 Sep, 2022

You are reading this latest preprint version

Randomized in situ evaluation of surface polishing protocols on the caries-protective effect of resin Infiltrant

Status:

Version 1

Abstract

Figures

Introduction

Materials And Methods

Results

Discussion

Declarations

References

Additional Declarations

Status:

Version 1